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TASK 2 Appendix PRELIMINARY DAMSITE INVESTIGATION Eagle River Water Resource Study 14, 1:P 0;V, Municipality of Anchorage Water and Sewer Utilities CH2MBIHILL December 1981 TASK 2 Appendix PRELIMINARY DAMSITE INVESTIGATION Eagle River Water Resource Study Municipality of Anchorage Water and Sewer Utilities LU US Department of Commerce NOAA Coastal Services Center Library 2234 South Hobson Avenue Charlestong SC 29405-2413 CF12MNHILL December 1981 Cover photo by: Air Photo Tech, Inc. 46 dmp 'Oq@% 00 49th 0- ----- L Y J OAMRONI .4092-E This report was prepared under the supervision of a registered professional engineer. The preparation of this report was financed in part by funds from the Office of Coastal Zone Management, National Oceanic and Atmospheric Administration, U.S. Department of Commerce, admin- istered by the Division of Community Planning, Alaska Department of Community and Regional Affairs. K13765.CO PREFACE To pursue the recommendations for further study that were pre- scribed in the Metr Anchoraqe Urban Study, completed.by the U.S. Corps of Engineers in 197-9, The-Municipality of Anchorage engaged CH2M HILL to conduct the Eagle River Water Resource Study. The purpose of the study is to investigate the potential sources of water supply from the Eagle River Valley. The original scope of the study comprised four tasks: Task 1 Well Drilling Program Task 2 Preliminary Damsite Investigation Task 3 Flour Water Treatment Study Task 4 Transmission Main Design Task 5, Eklutna Lake Alternative Water Source Evaluation, was added to the scope after the completion of the first four tasks. The report for each task is bound separately and is an appendix to the Executive Summary of the entire study. This Appendix 11 is the report for Task 2, Preliminary Damsite Investigation. ACKNOWLEDGMENTS We were a 'ssisted throughout the study by the Anchorage Water and Sewer Utilities staff. Dr. Robert Carlson, Director of the Institute of Water Resources, University of Alaska at Fairbanks, provided assistance on the flood frequency, sedimentation, and ice analyses. Eklutna, Inc. provided pertinent information at the weekly meet- ings and ready access to its property. Exploration Supply and Equipment, Inc., provided the drilling for the field exploratory borings. Harding-Lawson Associates, Anchorage, Consulting Engineers and Geologists, conducted part of the laboratory testing on the soil samples. Lindvall, Richter & Associates, Los Angeles, prepared the prelim- inary seismic evaluation, Exhibit C, for this project. Air Photo Tech, Inc. provided the aerial photographs. We wish to express our appreciation to these people and organiza- tions for their assistance and for their cooperation during the course of this study task. v SUMMARY AND CONCLUSIONS The purpose of the Eagle River Water Resource Study, which consists of five separate tasks, is to study the potential of de- veloping the Eagle River Valley as a source of municipal and in- dustrial water supply for the Municipality of Anchorage. Task 2, the subject of this report, is a preliminary damsite investigation for use in determining the feasibility of developing Eagle River as a surface water supply source. Two damsites were identified for study. Preliminary investiga- tions were conducted for each site to determine the size of dams that would form reservoirs capable of meeting a constant diversion of 73 cfs (47 mgd) and 108 cfs (70 mgd). Based on these analy- ses, the lower damsite, located 1-1/2 miles east of the Glenn High- way bridges, was chosen as the preferred site. These analyses also indicated that it would be more practical to construct the dam to provide the ultimate desired water supply demand rather than attempting to stage construction as the water supply demand increases. A dam can be constructed at the preferred damsite to meet a water supply demand of up to 108 cfs, provided there are no major deviations from the fol-lowing assumptions used in the investigation: 0 31 cfs (20 mgd) is adequate for minimum downstream releases 0 Mitigation of fisheries could be achieved to the satisfac- tion of controlling agencies 0 Other environmental impacts would not prohibit con- struction of the dam or use of water from the river 0 Special interest groups would not intervene to block construction of the dam or water use 0 Sediment deposition in the reservoir could be minimized by draining the reservoir during the summer when the sediment load in the river is the highest 0 All permits and licenses could be obtained from the ap- propriate agencies A constant water demand of 108 cfs was used to prepare the con- ceptual design of the dam and appurtenances. The conceptual dam design was prepared only for the preferred damsite, as identified by the Anchorage Water and Sewer Utilities. The pro- posed Eagle River dam would be constructed of compacted earth vii fill, approximately 80 feet high, with a crest length of about 800 feet. The embankment would have a nominal crest elevation of 350 feet, National Geodetic Vertical Datum (NGVD). The normal pool surface would be at elevation 338 feet, with a reservoir sur- face area of 2,530 acres, and a total storage volume of approxi- mately 55,000 acre-feet. The maximum pool surface, achieved only under the most critical flood conditions, would be at about eleva- tion 344.5 feet, with a reservoir area of approximately 2,840 acres and a total storage volume of 71,200 acre-feet. The spillway would be a reinforced concrete chute with a horizontal apron still- ing basin. The spillway discharges would be controlled by three 30-foot-square radial gates. Two 10-foot-square low-level outlet conduits would be provided for reservoir drainage and summer sediment bypassing, and a 3-foot-diameter outlet pipe would pro- vide water for minimum streamflow and for fish facilities. The low-level outlet gates would be open during the summer and the reservoir would be near empty to allow passage of the high sediment-laden river flows. During late August the low-level outlets would be closed to begin storing water for later use. The minimum downstream releases would be met at all times. The reservoir normally would fill by mid-October and would be drawn down as needed to meet the water supply demand during the win- ter and spring. On or about May 1, when river flows are suffi- cient, the low-level outlets would be opened and the reservoir drained. Based on our hydrologic, geologic, and geotechnical analyses, the proposed dam can be constructed to safely withstand the maximum credible earthquake and the probable maximum flood. This dam is estimated to cost $23,240,000 in April 1981 dollars. This amount is for construction and engineering only, and does not include land acquisition, financing, escalation to a future con- struction date, or fish facilities. Many uncertainties encountered during the preliminary damsite investigation need to be resolved by additional studies before any dam on the Eagle River can be designed. If the Anchorage Water and Sewer Utilities decides to proceed with design of the Eagle River dam, we recommend the following studies or actions be com- pleted prior to or during design: 0 Determine the type, number, migration pattern, and distribution of fish in the river 0 Determine the potential effect of the old Eagle River dump on reservoir water quality and evaluate any modi- fications required to develop the Eagle River as a water source viii 0 Study 'the variability of the water supply demand throughout the year 0 Install at least one precipitation station in the upper reaches of the basin to provide hourly precipitation data, and modify other stations in and around the basin to provide hourly precipitation data 0 Recompute the probable maximum flood during design 0 Study the winter regime of Eagle River 0 Perform a more detailed seismicity study for the site 0 Perform additional subsurface exploration surrounding the damsite 0 Perform additional borrow exploration and testing for select materials such as core and filter materials 0 Study the effect of not stripping vegetation from the reservoir 0 Conduct a sediment sampling study to provide data for reservoir sedimentation estimates ix CONTENTS Page Preface iii Acknowledgements v Summary and Conclusions vii 1 1 ntroduction 1-1 Background 1-1 Purpose and Scope 1-5 Site Description 1-5 Limitations 1-9 2 Major Design Considerations 2-1 Sa fety 2-1 Water Supply Requirements 2-1 Spillway Capacity and Operation 2-1 Seismic Design 2-2 Freeboard 2-2 3 Hydrology and Hydraulics 3-1 Basin Description 3-1 Climate 3-2 Streamflow 3-3 Flood Frequency 3-7 Flood Profiles and Boundaries 3-8 Spillway Design Flood 3-9 Sedimentation 3-12 Ice 3-15 Reservoir Operations and Firm Yield Analysis 3-16 Hydroelectric Generation Potential 3-20 4 Geology 4-1 Regional Geology 4-1 Local Geology 4-4 Geologic Hazards 4-15 Previous Geologic Studies 4-17 5 Field Exploration 5-1 Field Exploration Activities 5-1 Subsurface Conditions 5-2 6 Laboratory Testing 6-1 Classification Tests 6-1 Engineering Properties Tests 6-3 xi 7 Environmental Considerations 7-1 Identification of Environmental Concerns 7-1 Environmental Concerns 7-2 Summary 7-7 8 Major Project Elements 8-1 Foundation and Abutments 8-1 Dam Section 8-6 Spillway 8-15 Stilling Basin 8-18 Outlet Works B-18 Reservoir 8-20 9 Construction 9-1 Areas of Uncertainty 9-1 Construction Sequence 9-2 Construction Schedule 9-3 Diversion and Care of Water 9-3 Cost Estimate 9-4 Permits 9-6 Construction Review 9-8 10 Operation and Maintenance 10-1 Operation 10-1 Emergency Warning Plan 10-2 Maintenance 10-3 1 nspection 10-4 Effects of Future Changes 10-5 11 Conclusions and Recommendations 11-1 Conclusions 11-1 Recommendations 11-1 12 Bibliography 12-1 EXHIBITS Exhibit A. Streamflows Exhibit B. Reservoir Operations Exhibit C. Preliminary Seismic Evaluation Exhibit D. Harding-Lawson Associates, Summary of Laboratory Tests Exhibit E. CH2M HILL, Summary of Laboratory Tests xii TABLES Page 3-1 Average Discharge from the Eagle River 3-4 3-2 Eagle River Flood Frequency 3-8 3-3 Estimated Wash Load, Bed Load, and Total Sediment Load for a Typical Water Year (1978) 3-14 3-4 Reservoir Operations Summary (73 cfs) 3-18 3-5 Reservoir Operations Summary (108 cfs) 3-19 4-1 Legend for Map Units in Figure 4-1 4-7 6-1 Eagle River Dam Project, Summary of Laboratory Soil Tests 6-2 8-1 Material Properties 8-11 9-1 Construction Cost Estimate 9-5 xiii FIGURES Page 1-1 Vicinity Map 1-2 1-2 Projected Water Demand Increase, 1980-2025 1-3 1-3 Reservoir Plan 1-7 3-1 Eagle River Drainage Basin 3-23 3-2 Eagle River at Eagle River, Daily Discharge Hydrographs, 1966-1969 3-25 3-3 Eagle River at Eagle River, Daily Discharge Hydrographs, 1970-1973 3-26 3-4 Eagle River at Eagle River, Daily Discharge Hydrographs, 1974-1977 3-27 3-5 Eagle River at Eagle River, Daily Discharge Hydrographs, 1978-1980 3-28 3-6 Low, Average, and High Monthly Flows 3-29 3-7 Daily Flow Duration Curves 3-30 3-8 Low-Flow Frequency Curve 3-31 3-9 Flood Frequency Curve 3-32 3-10 Approximate Flood Profiles, Study Mile 0 to 2. 7 3-33 3-11 Approximate Flood Profiles, Study Mile 2.7 to 5. 3 3-35 3-12 Approximate Flood Profiles, Study Mile 5.3 to 8. 0 3-37 3-13 Approximate Flood Profiles, Study Mile 8.0 . to 10.6 3-39 3-14 Approximate Flood Profiles, Study Mile 10.6 to 13.3 3-41 3-15 Approximate Flood Profiles, Study Mile 13.3 to 15.9 3-43 3-16 Approximate Flood Profiles, Study Mile 15.9 to 18.6 3-45 xv 3-17 Approximate Flood Plain Boundaries, Study Mile 0 to 4.1 3-47 3-18 Approximate Flood Plain Boundaries, Study Mile 4.1 to 10 3-49 3-19 Approximate Flood Plain Boundaries, Study Mile 10 to 15.5 3-51 3-20 Approximate Flood Plain Boundaries, Study Mile 15.5 to 18.7 3-53 3-21 Approximate Reservoir Limits, Study Mile 0 to 4.1 3-55 3-22 Approximate Reservoir Limits, Study Mile 4.1 to 10 3-57 3-23 Approximate Reservoir Limits, Study Mile 10 to 15.5 3-59 3-24 Approximate Reservoir Limits, Study Mile 15.5 to 18.7 3-61 3-25 One-hour Unit Hydrograph 3-63 3-26 PMF Inflow and Routed Outflow 3-64 3-27 Eagle River at Eagle River, Suspended Sediment Load, 1966-1972 3-65 3-28 Eagle River at Eagle River, Sediment Size Analysis, 1966-1972 3-66 3-29 Lower Damsite Area/Capacity Curves 3-67 3-30 Spillway Rating Curve for a 30-Foot-Wide Gate 3-68 3-31 Low-level Outlet Works, Rating Curve for Conduit 3-69 3-32 Low-Level Outlet Works, Rating Curve for Pipes 3-70 3-33 Lower Damsite Tailwater Rating Curve 3-71 4-1 Regional Geologic Map 4-5 4-2 Damsite Geologic Map 4-11 5-1 Exploration Plan 5-5 5-2 Damsite Boring Logs, B-1 through B-3 5-7 xvi 5-3 Damsite Boring Logs, B-4 through B-6 5-8 8-1 Major Project Elements 8-3 8-2 Dam Section 8-5 8-3 Dam Profile 8-7 8-4 Stability Analysis 8-13 8-5 Spillway Profile 8-16 xvii ME Chapter 1 INTRODUCTION BACKGROUND The population and, thus, the water supply needs of the metro- politan Anchorage area are rapidly growing. Presently, water to Anchorage is principally supplied by surface water from Ship Creek and by groundwater wells in the Anchorage Bowl. How- ever, if present growth trends continue, these sources will not meet future needs. In 1974 the United States Congress authorized the U.S. Army Corps of Engineers to perform the Metropolitan Anchorage Urban Stud (MAUS), which was completed in 1979. The puFp`ose 7 Fthe ITKA was "to evaluate the adequacy of the developed water sup- ply in the metropolitan Anchorage area, to determine future water demands, to assess sources for water supply development, and to formulate water supply plans to meet the increased future de- inand" (U.S. Army Corps of Engineers, 1979). The MAUS study area comprised the Anchorage Bowl and the area northeast to the town of Eklutna (Figure 1-1). The projected future water demand increases, determined in the MAUS, are shown in Figure 1-2. It is expected that by the year 2025 an additional 81.5 million gallons per day (mgd) of water will be needed to meet the increased demands in the area. The MAUS report identified many potential sources of supply: Eagle River Valley groundwater; Anchorage Bowl groundwater; and surface water from Campbell Creek, Ship Creek, Eagle River, and Eklutna Lake. Two plans were recommended by MAUS for future study. Plan IV, which ranked first environmentally and socially, included a combination of supply from Ship Creek, An- chorage Bowl groundwater, and Eklutna Lake. Plan VI, which ranked first on an economic basis, included an increased supply from Ship Creek, winter diversion from Eagle River, further de- velopment of Anchorage Bowl groundwater, and exploration for Eagle River Valley groundwater. To increase the existing water supply sources within the Anchor- age Bowl, the Municipality recently constructed a 36-inch supply main to its water treatment plant from the military diversion facil- ity on Ship Creek. Other developments are expected to include new wells to increase groundwater supply and the expansion of the Municipal Water Treatment Plant facilities. However, rapidly growing demands in Anchorage require development of a new source outside the Anchorage Bowl within the next 10 years. The Eagle River-Chugiak-Eklutna area, northeast of Anchorage, needs a new source now. 1-1 0 00 0 0 0 CP C IS S KNIK D Irk A LENN OLD if OF 4, @,_ ,, @!, ,,-,@:i J, _,CJH@ 0 ETERS Rq11 REEK EKLUTNA LAKE CHLIGIAK 0 TOWN OF EAGLE RIVER RR -AMP BRIDGE EA LE R1 E AM A E ER FORT RICHARDSON RV PU EIMENDORF FS AIR FORCE ASE YLE RIVER VALLEY PIPELI M N P ATE EKLUTNA ANCHORAGE T EA T L RI GLACIER CHUGACH MOUNTAINS EAGLE GLACIER 0 Miles 5 __j *As recommended in this study Figure 1-1 1-2 Vicinity Map cn 0 c WATER DEMAND INCREASE (mgd) w 1980 1985 CD 1990 1995 2i 0 m 2000 3 2005 2010 0 %F. r D - IN 2015 C) (D (D -L CL 2020 16 tD 2025 Ul m CL As a result of the MAUS findings, the Municipality decided to investigate potential sources outside the Anchorage Bowl that could supply 70 mgd of water. On the basis of the MAUS popu- lation projection, this diversion would satisfy the demands of the entire study. area through the year 2012. The increases in water supply capacity that are expected to be developed within the An- chorage Bowl would delay the need for the full 70-mgd capacity of the new water source outside the Bowl until approximately the year 2020 or longer. To investigate possible sources of water supply outside the An- chorage Bowl, the Municipality engaged CH2M HILL to conduct the Eagle River Water Resource Study. This original scope of the study comprised four separate tasks to investigate the Eagle River Valley as a potential source of municipal and industrial water supply: � Task 1, a well drilling program to study the feasibility of developing the Eagle River Valley as a groundwater source � Task 2, a preliminary damsite investigation to determine the feasibility of developing the Eagle River as a sur- face water source � Task 3, an investigation to determine if the glacial rock flour in the Eagle River water is removable by conventional treatment processes � Task 4, preliminary design of a pipeline to transport groundwater or surface water from the Eagle River Valley to Anchorage Each task was conducted independently. The results of the first four tasks clearly indicate that a substan- tial dam and reservoir are required to develop Eagle River as a water source. Before committing itself to this dam and reservoir project, the Municipality of Anchorage increased the study scope to include Task 5, Eklutna Lake Alternative Water Source Evalua- tion, to analyze the capability of Eklutna Lake to supply the 70 mgd of water to the area. The lake is 30 miles northeast of downtown Anchorage and 16 miles northeast of the Eagle River (Figure 1-1 ). The report of each task appears as an appendix to the Executive Summary of the entire study. This appendix is the report for Task 2, Preliminary Damsite Investigation. 1-4 PURPOSE AND SCOPE In Task 2, a study was performed to identify the preferred site and size for a dam that would fulfill certain criteria. The Eagle River dam and reservoir are to store a sufficient quantity of water during late summer and fall to provide a constant supply of 108 cfs (70 mgd) to a treatment plant. In addition, minimum streamflow below the dam would have to be maintained. Summer withdrawals for water supply can be made from the river without significant impoundment. Therefore, the reservoir would be drained during the summer, and the river would allowed to flow near its natural level. This would minimize sedimentation in the reservoir and the dam's impact on Eagle River summer flows. This report contains the results of field and laboratory tests, the engineering analysis of the proposed damsite, and the conceptual design of the dam and appurtenances. Included within these top- ics are discussions of: � Major project objectives � Hydrology and hydraulics � Regional and site geology � Preliminary evaluation of seismicity � Environmental considerations � Dam alignment and geometry � Preliminary cost estimate � Construction operation and maintenance considerations � Conclusions and recommendations The conceptual design of the dam, an approximate construction cost estimate, and recommendations for required studies are pre- sented to aid the Municipality of Anchorage in comparing the Eagle River Valley with other potential water sources. SITE DESCRIPTION As shown on the vicinity map, Figure 1-1, the major elements of the Eagle River Water Resource Study are the proposed Eagle River dam and reservoir, pump station, pipeline, and the exist- ing Municipal Water Treatment Plant. The location of the Eagle River water treatment plant has not yet been established. Initially, the Anchorage Water and Sewer Utilities (AWSU) re- quested that two damsites be considered: the site discussed in this report and an alternative site located approximately 1 mile upstream. The locations of both sites are shown on Figure 1-2. These two sites were suggested by previous investigators (Bate- man, 1948; Retherford et al., 1966; U.S. Army Corps of Engi- neers, 1979) as potential clamsites. 1-5 At the start of this task, conceptual layouts of the dams were prepared for each site. The hydraulic structures would be simi- lar at either site. The embankment volume at the alternative site would be approximately three times the embankment volume at the lower site. In addition, aerial photograph interpretation indicates that the Eagle River in the vicinity of the alternate site has me- andered back and forth across the valley floor, reworking the flood plain sediments. This suggests that the near-surface soils may be fine-grained and loose. If so, they would be subject to liquefaction during seismic loading unless they are densified or replaced. The depth of soil influenced by the meandering of the river is unknown. At the alternative site, it also would have been necessary to excavate large summer bypass channels both upstream and downstream of the dam because of unfavorable existing river channel geometry. These preliminary findings were presented to AWSU at a project meeting -on November 4, 1980. It was suggested that the study concentrate on the lower site unless it proved to be unsuitable. AWSU concurred with this approach. In general, this report dis- cusses only the lower damsite. The proposed Eagle River damsite is located in Section 13, Town- ship 14 North, Range 2 West. The site is approximately 1-1/2 miles east of the Glenn Highway bridges. The reservoir will ex- tend upstream approximately 6 miles. A plan of the reservoir and vicinity is shown on Figure 1-3. The drainage basin consists of a broad U-shaped valley in the Chugach Mountains. The valley walls are steep, rising to eleva- tions of 5,000 to 6,000 feet (elevation is based on the National Geodetic Vertical Datum of 1929). The valley floor and the lower valley slopes are covered with organic topsoil and decomposing vegetative material. This area supports scattered deciduous and evergreen trees. The upper valley slopes support little vegeta- tion. The river elevation at the damsite is approximately 270 feet. The maximum elevation in the watershed occurs at the peak of Mt. Yukla elevation 7,535 feet. The uppermost portion of the valley is @illed by the Eagle Glacier. The areas immediately surrounding the proposed reservoir are sparsely populated. The Eagle River area has a population of approximately 6,000 and lies approximately 1 mile north of the damsite. Eagle River Campground is located about 1 mile down- stream of the proposed damsite on the south bank of the river, and the Glenn Highway bridges are located about 1-1/2 miles downstream. Approximately 2 miles downstream of the proposed damsite, the Eagle River enters Fort Richardson. There is an electrical transmission line located approximately 3 miles down- stream of the site, and the Alaska Railroad crosses the Eagle River approximately 3-1/2 miles downstream from the site. 1-6 RIV X, Eagle Riv&r Camilground EAGLE DAM Alternative Damsite OLD E LE RIVER DUMP EAGLE 7 Prive 400 tw, (q@ Normal water surface e 1000 0 1000 2000 3000 4000 5000 FEET 338 feet (103.0 meters) LIMITATIONS This report has been prepared for the use of the Anchorage Water and Sewer Utilities for specific application to the Eagle River Water Resource Study preliminary damsite investigation, in accordance with generally accepted engineering practice. No other warranty, expressed or implied, is made. In the event that any changes in the nature or location of the dam or reservoir are made, the conclusions and recommendations contained in this re- port shall not be considered valid unless the changes are re- viewed and the conclusions or recommendations are modified or verified in writing by CH2M HILL. 'The analyses and recommendations presented in this report are based in part on widely spaced borings and surface observations. Variations in subsurface conditions are expected to exist between these points. The nature and extent of such variations may not become apparent until construction. When variations are encoun- tered, it will be necessary to reevaluate the conclusions and re- commendations presented in this report. The performance of an earth dam is highly dependent on the subsurface conditions, and project design must continue into the construction period. The conceptual design presented in this report is believed to be workable, but the design concepts are not refined enough at pre- sent for incorporation into a final design. Additional investiga- tions will be required to complete the design of the Eagle River dam. 1-9 RE Chapter 2 00 MAJOR DESIGN CONSIDERATIONS The conceptual design of the Eagle River dam has been accom- plished in accordance with commonly accepted standards for the design of @arth dams and with criteria requested by the Munici- pality of Anchorage Water and Sewer Utilities (AWSU). This chapter identifies, in broad terms, the major considerations used in the conceptual design of the dam: safety, water supply requirements, spillway capacity and operation, seismic design, and freeboard. SAFETY Eagle River dam must be designed to be safe under all conditions that can reasonably be expected to occur, such as large floods and earthquakes. Conservative design details, such as extra freeboard and flat slopes, can provide a measure of safety against conditions that cannot be predicted, such as ground tilting dur- ing major earthquakes. WATER SUPPLY REQUIREMENTS AWSU requested that the study be conducted for water supply requirements of both 47 and 70 million gallons per day (mgd) con- stant flow and that consideration be given to the feasibility of building the dam in stages as the water demand increases. All designs must also maintain minimum stream releases for the downstream fishery. SPILLWAY CAPACITY AND OPERATION The U. S. Army Corps of Engineers (1975) recommends that spill- way design floods be based on the dam's storage capacity and on the potential hazard to property and human life downstream of the dam. Using their standards, the dam would be classified "large" because the maximum storage volume of the proposed Eagle River reservoir exceeds 50,000 acre-feet. The dam would be placed in the "high" hazard potential classification, because there are more than a few residences (temporary, at the campground) downstream of the dam that may be flooded in the event of dam failure. Also, the Glenn Highway and, the Alaska Railroad bridges are of eco- nomic importance. The hazard classification is based solely on the potential for damage or loss of life downstream in the eve6t of dam failure, and does not in any way consider the dam's condition or safety. The Corps of Engineers recommends that the spillway design flood for a large-size, high-hazard dam be equal to the probable maxi- mum flood (PMF). In addition, a spillway capacity adequate to 2-1 safely pass the PMF is desirable because of the importance of the Eagle River reservoir in maintaining water supply to the Anchor- age area, AWSU wishes to minimize the impact of the reservoir on upstream land in the Eagle River Valley. To do this, the spillway has been designed so that under most conditions the reservoir surface will vary as little as possible above the normal water level. During the peak flow of the PMF, a maximum surcharge of about 6.5 feet is expected over the normal reservoir surface elevation. SEISMIC DESIGN Because of the importance of the Eagle River reservoir in main- taining water supply for the Anchorage area and the potential downstream threat in the event of dam failure, earthquake- resistant design will be a critical element of the final design pro- cess. Ancillary structures such as the spillway, gates, access bridges, outlet conduits, and the control tower Must be designed to withstand the maximum credible earthquake (MCE) and still be operational. Suitable methods of structural analysis are available to do this type of design. The embankment must be designed to limit to a tolerable amount the permanent deformation that would occur during the MCE. While there are no widely accepted standards for the earthquake- resistant design of embankments, much recent progress has been made in formulating design guidelines for potential settlement dur- ing earthquake shaking. For purposes of this conceptual design, the simplified analysis method proposed by Newmark (1965) was used to estimate the amount of crest settlement that may occur during the MCE. Additional freeboard has been provided to ac- count for the potential settlement that may occur during seismic loading. FREEBOARD There are no rigid, established standards for determining the amount of freeboard required for a given earth dam; however, a substantial amount of experience exists that provides guidance in this area. In general, freeboard amounts must be determined by using the following items, which were considered in this study- 0 Maximum wave height 0 Maximum wave runup 0 Ex pected crest settlement after construction 0 Ex pected crest settlement during seismic loading 0 Setup or reservoir surface tilt caused by wind 0 Residual freeboard allowance to account for unknowns 2-2 Chapter 3 HYDROLOGY AND HYDRAULICS This chapter presents the results of the hydrologic and hydraulic analyses made as part of the preliminary damsite investigation. The principal tasks performed are listed below: 0 Review the existing data and reports on the river and drainage basin 0 Determine the peak flows for floods with 10-year, .100-year, and 1,000-year recurrence intervals 0 Develop flood profiles and identify flood limits for floods with 1 0-yea r, 1 00-yea r, and 1,000-year recurrence intervals 0 Determine the low flow frequency 0 Determine the spillway design flood (PMF) 0 Consider potential reservoir sedimentation and - ice effects 0 Perform a firm yield analysis and reservoir operation stud y 0 Develop the hydraulics for the spillway and outlet works 0 Assess the possibility of developing hydroelectric gen- eration capacity as a part of the project BASIN DESCRIPTION The U.S. Geologic Survey (USGS) established a stream gage on the Eagle River in October 1965 (USGS Station No. 15277100). This gage is 0.6 mile upstream of the Glenn Highway bridges and 8 miles upstream of the river mouth. The elevation of the gage is 250 feet. The average basin elevation upstream of the gage is 2,600 feet, with several peaks over 7,000 feet. Raven Creek and the North and South Forks flow into the Eagle River above the gage. The Eagle River drainage basin, upstream of the (USGS) stream gage, consists of about 192 square miles of glaciers, steep moun- tain slopes, and a 1/2- to 1-mile-wide valley floor. This basin is 27 miles long and averages 7 miles in width. A map of the basin 3-1 is shown on Figure 3-1 The head of the basin is 34 miles east- southeast of Anchorage and 33 miles southeast of the mouth of the Eagle River. The mouth is 10 miles northeast of Anchorage. According to 1960 edition 1:63360 scale USGS maps, 17 percent of the basin is covered by glaciers. Eagle Glacier comprises 60 per- cent of the total glacial area. Numerous named and unnamed smaller glaciers make up the remaining area. These include Raven, Clear, Organ, and Flute Gla 'ciers. Eagle Glacier termi- nates at a small lake 35 river miles upstream from the mouth of the Eagle River at an elevation of 875 feet. The river is braided along the upper reach and meanders along the lower reach to the gaging station. The slope of the channel bottom varies from quite steep (1.4 percent) near the glacier to moderately steep (0.1 percent) between the North and South Forks of Eagle River. The surface of Eagle Glacier has slopes that range from 13.5 percent to 158 percent. Two clamsites (Figure 1-2) were considered initially for this study. The lower damsite is 1 mile upstream of the gage and the upper damsite is 3 miles upstream of the gage, measured along the river channel. The two damsites are about one mile apart in a linear measure. The area of the drainage basins of the two dams differs by only 4 square miles. The basin above the stream gage is one square mile larger than the lower damsite basin. The drainage area difference between the gage and the upstream dam- site represents only 2 percent of the total drainage area. This difference is not significant, since there is less precipitation at the lower end of the basin due to orographic effects. The hydro- logic analysis therefore assumed that the same flows occur at both damsites as at the stream gage. CLIMATE The Eagle River Basin is located in the transition zone between marine and continental influences. The climate of the basin is moderated by the Chugach Mountains, which act as a partial bar- rier to moist marine air from the south and east. Temperatures are moderated by the marine influences and precipitation is mod- erate to heavy. The upper end of the basin receives the greatest amount of precipitation due to its high elevation and proximity to Prince William Sound, through which many of the Gulf of Alaska storms pass. Mean annual precipitation ranges from about 20 inches at the USGS stream gage to more than 100 inches at the head of the basin. *Because of the large number of figures in this chapter, they have been placed at the end of the chapter so as not to impede the flow of the text. 3-2 Precipitation averages about 40 inches per year in the drainage basin. More than halt of the precipitation occurs in the period from July through October. Snow can fall at any time of the year in some parts of the basin. On the average, about 190 inches of snowfall occurs in the Eagle River Basin. The air temperature in the basin is estimated to average about 10 degrees Fahrenheit (F) cooler than the temperature at Anchor- age. The valley at the reservoir site experiences colder tempera- tures than Anchorage because of the glaciers and shading by the mountains. The average annual temperature of the basin is prob- ably about 25 degrees Fahrenheit. The coldest months are gen- erally January and February, and July is normally the warmest month. The average daily temperature in the basin is expected to be below freezing from mid-September through mid-May. STREAMFLOW Records taken at the USGS streamflow gage station are good ex- cept for those taken during the winter months, which are fair. Historical Records Streamflow records indicate that flow variations on an annual basis follow a fairly consistent pattern. Figures 3-2 through 3-5 are plots of the daily discharge hydrographs for the period from October I through September 30 of water years 1966 through 1980 at the Eagle River gage. The annual average flow, peak flows, and 30-day low flow are identified on these plots. Flows from November through May are usually low because of low tempera- tures and light precipitation. Summer runoff results from a com- bination of snow melt, glacial melt, and precipitation, and consti- tutes the bulk of the annual runoff. Summer runoff usually begins in June. Flows normally recede in August and September as cooler temperatures reduce glacial melt. The average flow in September and October is much lower than the average summer flow, but a few days of high discharge normally occur due to heavy precipitation. The mean annual discharge of Eagle River at the gage for water years (October 1 through September 30) 1966 through 1980 is 524 cubic feet per second (cfs). The annual flows have varied from a low of 394 cfs in water year 1973 to a high of 709 cfs in water year 1967. Monthly flows are listed in Table 3-1. A dia- gram summarizing the variability of the monthly flows is shown in Figure 3-6. Daily flow duration curves were plotted for the Eagle River and Ship Creek for the entire period of record at the Eagle River. These plots are shown in Figure 3-7. These plots show the per- cent of time that a given flow is expected to be equaled or exceeded. 3-3 Table 3-1 AVERAGE DISCHARGE FROM THE EAGLE RIVER Water Average Monthly Discharge (cfs) Mean Annual Year Oct Iq ov Dec Jan Feb Mar A @@a June July August Sept cfs mgd 11 pr 1966 425 162 83 52 50 50 51 235 1,150 1,858 1,958 1,177 608 393 1967 342 103 77 67 51 53 75 255 1,507 2,116 2,221 1,593 709 458 1968 288 133 82 72 64 61 63 356 961 1,775 1,450 476 485 313 1969 155 107 70 39 32 42 78 322 1 0252 1,564 874 457 418 270 1970 707 174 119 99 90 85 78 218 739 1,303 1,241 588 457 295 1971 181 103 75 57 52 40 36 82 725 1,772 2,002 552 478 309 1972 191 100 90 65 39 36 59 145 689 1,747 1,589 970 479 309 1973 418 143 123 74 48 44 71 160 662 1,290 1,227 430 394 255 1974 267 86 54 39 26 40 77 272 921 1,472 1,489 1,141 493 319 1975 231 123 81 48 44 44 77 313 746 1,652 1,307 756 456 295 1976 237 91 65 56 53 46 64 177 889 1,615 1,386 900 467 302 1977 307 190 130 94 79 62 78 249 1,333 2,120 2,424 1,100 686 443 1978 460 158 137 118 97 79 72 246 816 1,447 1,528 971 614 332 1979 324 116 72 65 61 69 117 366 1,082 2,001 2,103 1,098 618 399 1980 556 219 123 109 97 78 124 304 1,147 2,281 1,724 930 644 416 Mean 339 133 92 70 59 55 75 247 974 1,734 1,635 876 524 339 Percent of Annual 5.4 2.1 1.5 1.1 0.9 0.9 1.2 3.9 15.5 27.6 26.0 13.9 100 -- Minimum 155 86 54 39 26 36 36 82 662 1,290 874 457 394 255 Maximum 707 219 137 118 97 85 124 366 1,507 2,281 2,424 1,593 709 458 Source: USGS Water- Resources Data for Alaska, 1966-1980. SeepaQe_ Losses Along The River Three seepage investigations along the Eagle River have been conducted by USCS. These were made during periods of rela- tively constant flow on April 29, 1970, May 8, 1974, and Octo- ber 24, 1974. The April 1970 investigation was the most exten- sive, covering over 31 miles of the 35-mile river, and the October investigation covered a 16-mile central portion of the river. Some gains and losses in river flow are noted in the published data; however, the data might be erroneous and cannot support any conclusions about river flow. For example, one of the inves- tigations near the center of the drainage basin indicates a section of the river losing 37.9 cfs to seepage. However, this area has at least one side channel and at least one interconnecting channel with the North Fork. Flow in these channels, rather than seep- age, may account for at least part of the loss in measured flow from the main river channel. The potential for seepage from the reservoir and in the vicinity of the dam is discussed in Chapter 8. Flow Synthesis It is not reasonable to assume that the Eagle River stream gage has recorded the most critical (dry) year that may be experienced by the proposed reservoir during its life. Because only 14 years of recorded streamflow were available for the Eagle River gage at the time of the study, an attempt was made to correlate and ex- tend the record on the basis of nearby gaged streams with longer records. Ship Creek and Peters Creek records were used because these streams are adjacent to the Eagle River Basin and have streamflow records overlapping the Eagle River gage record. Monthly flows for these three streams were correlated through use of the Corps of Engineers HEC-4 stream flow simulation computer program (U.S. Army Corps of Engineers, 1971.) Monthly corre- lation coefficients were very low for all three streams. Low c'or- relation was expected because of the influence of Eagle Glacier. The average annual flow per square mile at the Eagle River gage was found to be about twice as high as at Ship Creek and Peters Creek. This is probably due to greater precipitation at higher altitudes. Flow variations on an annual basis correlated very well between Ship Creek and the Eagle River. However, they did not correlate well between Peters Creek and the the Eagle River. Therefore, Peters Creek was eliminated from further consideration. Climatological records at Anchorage are available from 1916 to the present (U.S. Department of Commerce, 1916-1979). Temperature and precipitation records were used to construct cumulative plots of annual precipitation, annual temperature, December-through- March average temperature, and February average temperature. 3-5 These plots were used as general flow predictors for the Eagle River since they indicate groupings of years that are either cooler and/or drier than normal. Records show that low temperatures, particularly in the winter, are associated with less than normal annual flow. Obviously, periods of low precipitation also indicate below-normal flows. The best predictor for low flows was found to be the December-through-March average temperature. Additional years of streamflow were generated based only on the statistics of the historical Eagle River gage record. The justifica- tion for using the historical records was that the cumulative temp- erature and precipitation plots indicate that the Eagle River gage records have been collected during a generally dry, cold period. Also, water year 1969 was the lowest runoff at the Ship Creek stream gage during the Ship Creek period of record (1947 to present). Therefore, it was assumed that the Eagle River gage has recorded at least one of the most critical (low flow) years since Anchorage and Ship Creek records began, which makes the 14 years of historical record reasonable for generating a series of flows that contain dry periods. Fourteen years of monthly flows were put into the Corps of Engineers HEC-4 program in order to generate 196 years of streamflow. Exhibit A contains the output from this program. The generated flows for the Eagle River are within the range of the historical flows. These flows were used as input for the reservoir operations analysis. Low Flow Low flows are very important in determining whether or not a stream is capable of meeting both the water demand and down- stream environmental needs. A study of monthly low flows was made to determine how often extremely low flows may occur. Based on historical data plus about 200 years of synthesized flows, a plot of the monthly low flow frequency was made. This plot is shown in Figure 3-8. The historical data points were also plotted on this figure to show the close relation between synthe- sized and historical data. Based on the plot, a minimum 30-day low flow of 20 cfs or less can be expected once every 100 years on the average. A minimum 30-day low flow of 32 cfs or less can be expected once every 10 years on the average. These data are important in establishing pre-dam conditions but have little direct effect on the ability of the proposed reservoir to meet water demand. The proposed reservoir would have several months of carryover storage and would not be sensitive solely to the 30-day low flow. However, conditions causing a 30-day low flow are likely to cause adjoining months to produce lower-than- normal flows that would affect reservoir operations. 3-6 FLOOD FREQUENCY An estimate of the flood frequency for the Eagle River was per- formed by Dr. Robert Carlson of the Institute of Water Resources, University of Alaska at Fairbanks. His findings were presented in a letter report to CH2M HILL dated August 1, 1980. The following is a summary quote from his study: A brief review of available streamflow, precipitation and snow course records indicated that- insufficient data exist for a sophisticated analysis attempting to relate many of the hydrologic variables of the basin. Instead, the Ship Creek, Eagle River and Peters Creek flow records were used to determine regional flood frequency relation- ships. Ship Creek has the longest record, while the Peters Creek record is almost too short to be of value. Other streams were investigated but were discarded because of insufficient re- cords. In Dr. Carlson's opinion: The flow records are considered to represent a homogene- ous base in both space and time. Any differences (that) the statistical analysis may show should be explainable by observable basin characteristics. The maximum instantaneous discharge for each year was chosen for use in determining the flood frequency relationship for each gage. Flow data were plotted on log-normal probability scales for the Eagle River, Ship Creek, and Peters Creek. Due to the paucity of data, a graphical rather than analytical method of analysis was used to fit the flood frequency curves on.the plotted data sheets. A straight line fit was used for all three streams. The flood frequency curve for the Eagle River was studied on a regional basis using several different parameters. Annual floods versus the average annual flow, the drainage area, and the mean annual flood were each investigated for the Eagle River, Ship Creek, and Peters Creek. The mean annual flood versus annual flood relationship was determined to provide the best regional indicator of flood frequency because of the distribution of plotted points. To determine the regional flood frequency curve, the average flood for the period of record for each of the streams was deter- mined. A plot was then made using the theoretical flood fre- quency curve divided by the average flood for each basin. All three curves were plotted on a single figure. A graphical analy- sis of this plot was done to determine the regional flood frequency curve of the Eagle River. Figure 3-9 shows a plot of this curve along with a plot of the historic flood data from Eagle River. A summary of flood frequencies is shown in Table 3-2. 3-7 Table 3-2 EAGLE RIVER FLOOD FREQUENCY Frequency (Years) Flood Flow (cfs) 10 5,200 100 7,600 1,000 10,000 FLOOD PROFILES AND BOUNDARIES The hydraulic characteristics of the Eagle River were analyzed to provide estimates of flood profiles for the 10-year-, 100-year-, and 11,000-year-recurrence-interval floods. This was done to permit a comparison of natural flood limits with flood limits that would result from dam construction. Water surface elevations were computed using the HEC-2 step backwater computer program (U.S. Army Corps of Engineers, 1979). Cross sections for the backwater analyses were scaled from 1:2400 scale topographic maps with a contour interval of 4 feet (Munici- pality of Anchorage, 1978). The underwater portions of the cross sections were estimated from field observations. The locations of the cross sections used in the hydraulic analyses are shown on the flood profiles (Figures 3-10 through 3-16) and on the flood- plain boundary maps (Figures 3-17 through 3-20). Channel and overbank roughness factors (Manning's 'In") for the backwater computations were assigned on the basis of inspection of aerial photographs (Air Photo Tech, Inc., 1979), aerial recon- naissance, and limited field observations of flood plain areas. Manning's 'In" values ranged from 0.030 to 0.050 in channel sec- tions and from 0.10 to 0.15 in overbank areas. The hydraulic analyses for this study are based on the effects of unobstructed flow. The flood elevations shown on the profiles are valid only if substantial amounts of debris or ice do not col- lect in the flow path. Higher flood levels can be expected to re- sult from log jams or ice jams. The accuracy of the computed water surface profiles is limited by lack of detailed field reconnaissance and cross-section surveys. More detailed effort was beyond the scope of this study. Com- puted water surface elevations are expected to be accurate to within 4 feet for floods of selected recurrence intervals. This study is not intended to take the place of a detailed flood study, 3-8 which would be conducted for the national flood insurance pro- gram. The flood* profiles are shown on Figures 3-10 through 3-16 for both pre-dam and post-dam conditions. The boundaries of pre-dam inundation for the 10-year, 100-year, and 1,000-year floods were plotted on the 1:2400 scale maps (Mu- nicipality of Anchorage, 1978) using the flood elevations deter- mined at each cross section. Between cross sections, the bound- aries were interpolated. These boundaries were then transferred to photo base maps at a scale of 1:12000 (Air Photo Tech, Inc., 1979). The pre-dam floodplain boundaries are shown on Fig- ures 3-17 through 3-20. In cases where the 10-year, 100-year, and 1,000-year flood boundaries are close together, only the 100-year boundary is shown. The approximate limits of the reservoir are shown on Figures 3-21 through 3-24. These limits are based on a normal water surface elevation of 338 feet. Small areas both within and outside the flood boundaries and res- ervoir limits might lie above or below the water surface eleva- tions shown. Because of limitations of the map scale and/or lack of detailed topographic data, all such areas cannot be delineated. SPILLWAY DESIGN FLOOD As stated in Chapter 2, the PMF was used as a basis for the spillway design. The PMF is the flood expected from the most severe combination of critical meteorologic and hydrologic condi- tions that are reasonably possible in the region. The PMF was based on the probable maximum precipitation, the.basin lag time, and historic flood records. Probable Maximum Precipitation The probable maximum precipitation (PMP) for the Eagle River Basin was determined by methods described in the U.S. Weather Bureau's Technical Report No. 47 (U.S. Department of Commerce, 1963). The PMP is not identified with any specific month, but may be more likely to occur in August, September, or October. The 24-hour PMP produces 6.7 inches in 6 hours, 9.5 inches in 12 hours, and 11 .6 inches in 24 hours. A storm more than 24 hours long was not considered because the spillway is sized to handle floods up to one-half the PMF without surcharging the reservoir (see Chapter 8). Therefore, longer duration floods would be passed directly through the reservoir without altering the flood-handling capability for the 24-hour PMP. Precipitation was plotted in the form of a depth-duration curve to aid in ob- taining incremental rainfall. The patterns of historical 24-hour rainstorms from January 1953 through October 1970 were reviewed 3-9 and used along with the the U.S. Weather Bureau's Hydrometeor- ological Report No. 43, to estimate a critical storm pattern (U.S. Department of Commerce, 1966). Basin Lag Time Basin lag time is a measure of a basin's response time to a storm. The basin lag is most frequently defined as the time from the centroid of effective rainfall to the hydrograph peak. The length of basin lag time has an important effect on the PMF. Lag time was estimated by a number of methods. Several preliminary lag-time estimates were made on the basis pf travel time of channel flow in the main stream only. The channel length and slope are important to this estimate. Using these parameters in empirical equations, calculations of basin lag time ranged between 3.8 and 7.1 hours. Since overland flow can in- crease the lag time substantially, estimates of lag time based on overland flow plus channel flow from the most distant points in the basin were also made. Lag-time values ranged from 6.0 to 9.8 hours using this method. Our experience with similar basins indicates that the lag time for the PMF would be more than the low-end estimate obtained from the empirical methods. Historical precipitation and streamflow data were also used to estimate the basin lag time. Hourly precipitation at Anchorage and hourly streamflow records at the Eagle River gage were used as predictors of lag time. The Anchorage climatological station experiences little orographic influence, but the station can be used as a general indicator of the timing and pattern of some of the larger rainfalls. Six-hour precipitation data from Elmendorf and the South Fork of the Eagle River were also used; however, only limited data are available from those sites. The lag time predicted by historical data ranges from 16 to 30 hours. While no data from large floods were available for analysis, the shorter lag times resulted from rainstorms of higher intensity. Consequently, the PMF lag time is expected to be even less than 16 hours. A shorter lag time for the PMF can also be expected since the high discharges could result in increased flow velocities. The lag time used for the PMF calculation was 11.5 hours. This value was chosen on the basis of our judgment, since historical records tend to provide too high an estimate, and empirical methods tend to provide too low an estimate of lag time for this type of basin. Prior to the final design of the dam spillway, it is recommended that at least one recording rain gage be installed in the upper reaches of the Eagle River Basin. This would be of great bene- fit in computing basin lag time and, in turn, computing the PMF. 3-10 Derivation of the Unit HydrograPh A unit hydrograph is an estimate of drainage basin runoff versus time that may result from a unit amount of effective rainfall (the portion that becomes runoff) occurring over a given period of time. Several unit hydrographs were developed for use in estimating the PMF at the Eagle River. The Soil Conservation Service method, as described in Design of Small Dams (U.S. Bureau of Reclamation, 1974), was used to de-ve-Fo-pa Unit hydrograph. The hydrograph analysis, based on historic floods and described in Design of Small Dams, was used to develop other unit graphs. 1I7cTuF5`f`ions-`oFT1/2 to 1 hour were studied. Rainfa The storm of September 11 to 19, 1978, was used as the basis of the final unit hydrograph. From the historical flood hydrograph, base flow was separated and a net hydrograph and corresponding dimensionless graph were derived. A J-hour unit hydrograph was then calculated from the dimensionless graph using the 11.5 hour estimated lag time. A plot of the unit hydrograph is shown in Figure 3-25 and represents an estimate of the runoff that may occur at the damsite from 1 inch of net rainfall occurring over a 1-hour period. The peak of the unit hydrograph is 11,360 cfs and the time to peak is about 12 hours. Probable Maximum Flood In order to compute the PMF, a base flow equivalent to the 100-year flood peak was assumed for the basin. This corresponds to 7,600 cfs. This base flow is equivalent to 1.5 inches (water equivalent) of snowmelt during the 24-hour storm and is consid- ered adequate to account for snowmelt and glacial melt conditions during the PMF. Much of the basin is very steep and rocky and would probably retain little water during the high intensity rain- fall that occurs during a PMP. No infiltration losses were used since the basin was assumed to be completely saturated by ante- cedent storms. This assumption is valid for this level of study; using a minimum infiltration rate may decrease the flood peak by as much as 10,000 cfs. The U.S. Army Corps of Engineers' computer program HEC-1, Flood Hydrograph Package (U.S. Army Corps of Engineers, 1973), was used to combine the PMP with the unit hydrograph and base- flow conditions to obtain the probable maximum flood. The PMF peak flood inflow to the reservoir is about 100,000 cfs. The PMF has a 100-hour volume of 134,000 acre-feet. The PMF hydrograph is shown in Figure 3-26. Routing of the PMF through the reservoir was conducted assuming that the low-level outlets are closed and the reservoir is at the normal operating elevation of 338 feet at the start of the PMF. 3-11 The spillway was assumed to be passing the 7,600-cfs base flow prior to the PMF. In general, the spillway gates were assumed to be opened as needed to match outflow with reservoir inflow, while holding the reservoir at approximately elevation 338. However, the gate opening rate was limited to a rate that would not cause downstream river levels to rise faster than 2 feet per hour. This rate is used to allow people downstream along the river a reason- able amount of time to leave the river area. The routed peak outflow during the PMF is about 79,000 cfs. The reservoir sur- charge is 6.5 feet, bringing the reservoir water surface elevation 344.5 feet. The routed outflow is shown on Figure 3-26. SEDIMENTATION Sediments carried by the Eagle River would be deposited in the quiet waters of the reservoir and would decrease its storage ca- pacity. Determination of the deposition rate in the reservoir re- quires knowledge of stream hydraulics, stream characteristics, total sediment discharge, trapping efficiency of the proposed res- ervoir, and the expected reservoir operation plan. Most of the required information is not available to make reason- ably accurate estimates of reservoir capacity depletion by sedi- mentation. The following information is available: 0 Daily stream discharges for the Eagle River for water years 1966 through 1980. The discharge measurements were made one mile downstream from the proposed dam- site. (USGS, 1966-1980) 0 Maps of the Eagle River Valley at a scale of 1:2400 with a contour interval of 4 feet. (Municipality of Anchor- age, 1978.) 0 Suspended sediment concentration and suspended sedi- ment size distributions collected irregularly from 1966 through 1972. (USGS Water Resources Data for Alaska) The above data are not sufficient to predict sedimentation rates in the proposed reservoir. However, these data can form the basis for estimates of the necessary parameters required for sedimenta- tion rate calculations. Stream Characteristics Stream characteristics of importance to sedimentation estimates include slope, cross-sectional areas, width, depth, wetted perim- eter, hydraulic radius, and streambed material types. Streambed materials were observed in the field and generally con- sist of 1-inch minus material, with some lenses of silt, sand, 3-12 gravel, and randomly scattered cobbles and boulders. The stream slope along the various stream segments was determined from the streambed profiles (Figures 3-10 through 3-16). The stream slope in the vicinity of the proposed Eagle River dam is about 0.3 percent. All other stream characteristic parameters are a function of stream discharge. The values of these param- eters in the vicinity of the proposed dam are presented below. Stream Hydraulics The USGS has made stream discharge measurements for the last 15 years (1966 to 1980). The recorded Eagle River discharge varies from about 30 to 6,000 cfs. The discharge values were put into a computer program from which flood width, depth, area, velocity, and energy gradient were obtained. Values for the sec- tion nearest the proposed Eagle River dam were extrapolated on a log-log plot to obtain representative values at lower discharge rates. Calculating sediment loads and sediment discharge as a function of only the mean annual discharge may introduce significant errors into the estimate. Therefore, it was decided to base sedimenta- tion estimates on the mean monthly discharge values for a typical water year. The year chosen was 1978, with a mean annual flow of 514 cfs, close to the average annual recorded flow of 524 cfs. The 1978 average monthly flows varied from 72 to 1,528 cfs. Ap- proximately 85 percent of the 1978 flow occurred during May through September, close to the average value of 87 percent. Sediment Discharge No total sediment discharge measurements for Eagle River have been taken. Suspended sediment load measurements were made at the stream gaging station at random intervals from 1966 through 1973. Figure 3-27 indicates the suspended sediment loads in tons-per-day as a function of stream discharge. The suspended sediment loads include both wash load and the sand portion of the bed load. Wash load is defined as sediment particles finer than 62 microns (silt, clay and colloids). Bed load is that material coarser than 62 microns (sand, gravel, cobbles and boulders). The measured suspended sediment loads are divided into wash load and bed load by determining the percentage of each on the basis of the particle size analysis of the suspended load samples, as shown in Figure 3-28. Suspended sediment loads, wash load, and measured sand portions of the bed load for the typical water year (1978) were then estimated. The bed load is estimated using the Colby (1957) method as outlined in Vanoni (1975). The total sediment load is a summation of the wash load and the bed load as a function of stream discharge. The estimate of the sediment loads carried by the Eagle River in the typical water year (1978) is given in Table 3-3. 3-13 Table 3-3 ESTIMATED WASH LOAD, BED LOAD, AND TOTAL SEDIMENT LOAD FOR A TYPICAL WATER YEAR (1978) Total Sediment Load Wash Load (Tons/Month) Bed Load (Tons/Month) (Tons/Month) Month Low Mean High --Co-w Mean H tg-F- Low M 6 -a-, Hiah Oct 840 2,370 6,590 2,020 3,130 5,740 2,860 5,500 12,330 Nov 140 410 1,140 390 660 1,170 530 1,070 2,310 Dec 150 430 1,170 400 680 1,210 550 1,310 2,380 Jan 80 240 690 250 400 780 330 640 1,470 Feb 40 100 290 140 200 300 180 300 590 Mar 30 70 210 120 190 220 150 260 430 Apr 20 60 160 120 120 180 140 180 340 May 200 600 1,660 740 1,240 2,560 940 1,840 4,220 Jun 2,160 6,070 16,880 5,670 10,290 19,680 7,830 16,360 36,560 Jul 6,430 18,270 51,460 11,320 20,710 38,440 17,750 38,980 89,900 Aug 7,200 19,840 55,800 13,210 23,620 45,040 20,410 43,460 100,840 Sep 3,440 9,840 27,060 6,150 11,370 21,630 9,590 21,210 48,690 Annual 20,730 58,300 163,110 40,530 72,610 136,950 61,260 130,910 300,060 Proposed Dam Operation Schedule The volume of sediment trapped in a reservoir behind a dam is greatly influenced by the dam operation schedule. The prelimi- nary operation schedule is based on water being stored and avail- able for use from September through April. When river flows are sufficient, the low-level outlets would be opened and the reser- voir would be drained. This is normally expected to occur in early May. From May through August, the outlet gates would be left open and the river would be allowed to flow close to natural conditions through the reservoir. Trapping Efficiency The trapping efficiency of the proposed Eagle River reservoir is unknown. For estimation purposes, three approaches were con- sidered. First, all of the sediment carried by the Eagle River through the reservoir section was assumed to be deposited during both summer and winter regimes. Second, all of the sediment carried by the river in the summer was assumed to pass through the reservoir section and continue downstream with little deposi- tion in the reservoir, with total deposition during the fall and winter months. The results of these two methods were judged to be quite conservative. Consequently, the Brune (1953) trap effi- ciency curve, based on the capacity-inflow ratio, was used to estimate the percentage of sediment trapped in the reservoir. 3-14 This method has been developed from data collected from many operating reservoirs. Consequently, it was judged to be the most realistic. The Brune trap efficiency curve predicts that 5,000 acre-feet of sediment would be deposited in the reservoir in 40 to 198 years; 91 years is the predicted mean filling time. Therefore, 5,000 acre-feet of sediment storage was considered adequate for use in the reservoir operation studies. Recommendations The sedimentation rates and the filling scenarios for the proposed Eagle River reservoir have been estimated on the basis of a mini- mal amount of data. In order to provide a better estimate, more precise values for bed load along the reservoir section of the river are needed. Preferably, at least one year's sediment dis- charge should be measured. Also, a better estimate of the trap- ping efficiency of the proposed reservoir would increase the ac- curacy of sedimentation estimates. Trapping efficiency can be more accurately estimated by determining stream characteristics and stream hydraulics for a series of closely spaced cross- sections along the reservoir segment of the river. The estimates of sedimentation would also be improved by calculating sediment discharges and potential sedimentation on a daily basis instead of a monthly basis. ICE Dr. Robert Carlson of the Institute of Water Resources, Univer- sity of Alaska, Fairbanks, assisted in identifying various potential ice effects. His findings were presented in a letter report to CH2M HILL dated October 20, 1980, and are summarized in this section. Careful consideration of ice effects is required for any proposed Eagle River reservoir. Several major ice problems related to the reservoir must be studied in more detail during final design of a dam. These problems include the growth of ice on the reservoir surface, ice jamming in the vicinity of various structures, ice forces, and frazil ice production and accumulation. Ice growth on the reservoir surface would cause a decrease in the available storage for water supply. Estimates of potential surface ice thickness indicate that about 4 feet of ice may develop during the colder years. With the reservoir at normal level, this would occupy about 10,000 acre-feet, a substantial volume. If the water level were lowered while the ice cover is growing, the edges of the ice cover would break and become beached before four feet of thickness is reached. Lowering the water surface would also 1- 15 expose less surface area to increased freezing, thus decreasing the volume of ice formed. To be conservative, 4 feet of ice was assumed to cover the full reservoir. Spring breakup could cause problems of ice-jamming in the vicin- ity of the gate structures and dam. If the reservoir ice cover is fairly solid when high spring flows begin to occur, the ice could be broken up and forced against the dam structures. The force of ice flows coming in contact with the various piers and gate structures must be considered in final design. Frazil ice production should also be carefully evaluated during final design. Large quantities of frazil ice could form in the steep upstream section of the Eagle River and in the South Fork of Eagle River. It is estimated that about 600 acre-feet of frazil ice might be produced annually. This frazil ice could accumulate under the reservoir ice cover as a hanging slush dam. Then, as the sl'ush works its way downstream, it could eventually clog the water supply intake area. The intake structure design would need to carefully consider potential frazil ice problems. The extent and nature of winter ice and frazil ice production is difficult to predict without further study of the winter regime of the Eagle River. A winter ice survey would be invaluable for fur- ther design of this project. Estimates made within the scope of this study are very rough and would be improved with field in- vestigations. Some parameters that should be determined in a survey include: ice thickness variation; type of existing ice regime; and whether the river is broken, open, or incurs large ice jams. Particular emphasis should be placed on frazil ice pro- duction in the river upstream of the reservoir, especially if it extends throughout the winter season, and on the nature of breakup in the existing channel. RESERVOIR OPERATIONS AND FIRM YIELD ANALYSIS Reservoir operations were simulated using the computer program HEC-3, Reservoir System Analysis for Conservation (U.S. Army Corps of Engineers, 1974). Exhibit B contains the output from this program. The operation studies were used to estimate res- ervoir size needed to satisfy firm yield and minimum reservoir release requirements. The firm yields required to be considered in this study were 73 cfs (47 mgd) and 108 cfs (70 mgd). The simulation was performed on a monthly routing of flows. The period included 14 years (1966-1979) of gage records for the Eagle River and 196 years of monthly stream flows simulated using the computer program HEC-4, Monthly Streamflow Simulation (U.S. Army Corps of Engineers, 1971). A net evaporation rate of zero was used throughout the operations analysis. 3-16 Physical features of the reservoir were taken from 1:2400 scale maps having a 4-foot contour interval (Municipality of Anchorage, 1978). Reservoir characteristics necessary to model the storage and release features of the impoundment include water surface elevation, storage capacity, surface area, and outlet capacity. Reservoir sizing criteria were analyzed. A diversion of 31 cfs (20 mgd) to meet minimum reservoir release requirements was used for all months in the simulation period. The State of Alaska Department of Fish and Game, in a November 4, 1980, letter to AWSU, stated that a 20-mgd downstream discharge might be ade- quate if no significant fisheries resources are found below the dam (State of Alaska, 1980). The same discharge was also used for the Metropolitan Anchorage Urban Study. (U.S. Army Corps of Engineers, 1979, page 3-89). This To-wrequirement was satis- fied prior to making any releases for water supply demands. Additionally, an inactive storage volume of 5,000 acre-feet was assumed necessary for sediment accumulation. An inactive storage volume large enough to allow a 4-foot ice accumulation on the reservoir surface was also assumed. The initial reservoir operations analysis was performed to deter- mine active storage requirements for a range of firm yields. It was assumed for this initial analysis that the reservoir would re- main as full as possible during the year. Subsequent analyses were performed to determine the effects on the firm yield if the reservoir is emptied during the highly sedi- ment-laden summer river flows. This was done for two different reservoir sizes. The smaller reservoir was sized for a firm yield of 73 cfs (47 mgd) plus 31 cfs for minimum reservoir release. The larger reservoir was sized for 108 cfs (70 mgd) firm yield, plus a minimum reservoir release of 31 cfs. A firm yield of 73 cfs for domestic use, plus 31 cfs for fish flow, requires a reservoir with an active storage capacity of 26,000 acre-feet and an inactive storage for ice and sediment accumula- tion of 13,300 acre-feet. This results in a normal reservoir ele- vation of 332 feet (Figure 3-29). Reservoir filling must begin near the last week in August to meet the demand. Operation of the reservoir, with the reservoir drained May 1 through Septem- ber 1, can provide 73 cfs during 99.5 percent of the time. If the reservoir is held empty through October 1, the firm yield decreases to 26 cfs (17 mgd). However, a domestic demand of 73 cfs can be satisfied about 8 out of 9 years if reservoir filling begins on October 1 each year. Table 3-4 indicates how often a given reservoir yield would not be met with various beginning fill- ing dates. For example, from Table 3-4 it can be seen that with an October 1 filling date the yield would be something less than 73 cfs on the average of once every 9 years. Likewise, the yield would be something less than 33 cfs on the average of once every 3-17 100 years. The breakdown of the beginning filling dates was not studied for increments smaller than 1 month. Therefore, the computer analysis showed that the reservoir filling must begin August 1 to meet a firm yield of 73 cfs. However, if smaller time increments were used they would most likely show the firm yield could be met with a beginning filling date of mid to late August. Table 3-4 RESERVOIR OPERATIONS SUMMARY (RESERVOIR YIELD OF 73 CFS) Date of a Fraction of Reservoir Filling Yield (cfs) Years When Yield Not Met August 1 73 Firm based on 200 years September 1 73 1/200 63 Firm. based on 200 years October 1 73 1/9 57 1/11 45 1/14 33 1/100 27 1/200 26 Firm based on 200 years aYield is in addition to 31-cfs minimum reservoir release. An active storage of 40,000 acre-feet and inactive storage for ice and sediment accumulation of 15,000 acre-feet are required to supply a domestic firm yield of 108 cfs, plus 31 cfs for minimum f low. This results in a normal reservoir elevation of 338 feet (Figure 3-29). The 108-cfs demand can still be met with the res- ervoir drained May 1 through mid to late August. If the reser- voir is held empty through September 1 the firm yield decreases to 63 cfs. However, a domestic demand of 108 cfs can be satis- fied about 14 out of 15 years if reservoir filling begins on Sep- tember 1 each year. Table 3-5 indicates how often a given res- ervoir yield would not be met with various beginning filling dates. In view of the above data, a typical yearly operation to supply a firm yield of 108 cfs plus 31 cfs for minimum reservoir release may be as follows. The low-level outlet gates would be open dur- ing the summer and the reservoir would be nearly empty. During this time of the year the river flows are greatly in excess of the water supply demand so the demand can be met with a minimum pool behind the dam. During late August or early September (depending on the year), the low-level outlets would be closed to 3-18 begin storing water for later in the season. The 31-cfs minimum flow would be released at all times. The reservoir would normally fill by mid-October. The reservoir would be drawn down as needed to meet water supply demand and minimum flow require- ments during the winter and spring. On or about May 1, when the operators are certain that the river flow will support the de- mand, the low-level outlets would be opened and the reservoir drained. The annual cycle would be complete at this time and the demand would again be met directly from the river flows. Table 3-5 RESERVOIR OPERATIONS SUMMARY (RESERVOIR DOMESTIC YIELD OF 108 CFS) Date of Fraction of Reservoir Filling Yield (cfs) a Years When Yield Not Met August 1 108 Firm based on 200 years September 1 108 1/15 102 1/30 94 1/40 74 1/100 73 1/200 63 Firm based on 200 years aYield is in addition to 31-cfs minimum reservoir release. Spillway and Outlets The 100-foot-wide spillway chute is provided to safely pass the PMF. Flow to the chute is controlled by three 30-foot-high radial gates. The spillway rating curve is presented on Figure 3-30. The low-level outlets allow for diversion during construction, lowering the reservoir in the summer to minimize the reservoir pool, adjustments of flow releases during small reservoir dis- charges, and possible future modifications for use in a hydro- electric development. Two 10-foot-square conduits controlled by roller gates and one 3-foot-diameter pipe penetrate the embank- ment near the spillway. Outlet rating curves are provided on Figures 3-31 and 3-32. The tailwater rating curve, Figure 3-33, was developed using the HEC-2 step backwater program (U.S. Army Corps of Engineers, 1979) and the river cross sections used to develop the flood profiles and boundaries. The spillway and outlets are described in more detail in Chapter 8. 3-19 Downstream Scour Trapping of sediments in a reservoir changes the balance between flow and sediment transport capacity. Therefore, the cleaner- than-normal river water downstream of the reservoir would tend to degrade (erode) the streambed as it picks up sediments from the channel. Substantial degradation of downstream channels has occurred under these conditions below many dams. The amount of degradation that may occur downstream of the Eagle River dam cannot be reliably estimated with existing data. A bedrock out- crop occurs in the river about one and one-half river miles down- stream of the dam, near the campground. This may limit channel degradation to some extent downstream of the dam. Downstream of the bedrock outcrop, degradation could occur to an unknown extent. However, the river would flow nearly uninterrupted during the summer since the outlet gates would be open. This should reduce the impact of the dam on downstream channel degradation, since the most sediment-laden flows generally occur in summer. Channel degradation should be considered in final design. HYDROELECTRIC GENERATION POTENTIAL The mean annual flow in the Eagle River at the damsite is roughly 4.5 times as large as the 108 cfs (70 mgd) water supply demand. Since a considerable amount of water would pass over the spillway or through the dam, a brief reconnaissance- level investigation was conducted to evaluate potential hydroelectric benefits. Since the reservoir's paramount function is to provide storage to meet water supply demand, no major modifications of the reservoir operation were considered for optimizing hydroelectric benefits. The average monthly flow released from the dam and the average monthly heads were obtained from the water supply reservoir operations studies. Normally the reservoir would be nearly full from September through April, thus providing significant head during this period. The normal discharge at the dam from November through April would be 31 cfs (20 mgd), the minimum downstream release. According to the reservoir operation plan, the reservoir would be empty during most of May through August to allow passage of the summer flows. Since the reservoir would be drained for 4 months of the year, hydroelectric potential at the site was considered to be minimal. A small but significant change in the reservoir operation plan was considered to improve the hydroelectric potential: the reservoir would not be drawn below the spillway crest elevation, 308 feet. The reservoir storage capacity at elevation 308 is about 8,000 acre-feet, all of which would become dead storage. Minor adjustments in dam height (about 2 feet) could be made to account 3-20 for this dead storage. This change in operations would provide a minimum head of 36 feet for hydroelectric generation. Using this minimum head and the design minimum discharge of 31 cfs, per- formance was evaluated for an adjustable propeller-type turbine- .generator. Design conditions and performance are: Design Discharge 125 cfs Design Head (net) 48 ft. Design Output 430 kW 6 Annual Energy Production 2. 46 x 10 kWh Plant Factor 66 percent The preliminary cost estimate for this hydroelectric development was based on the Feasibility Studies for Small Scale Hydropower Additions (U.S. Army Corps ngineers, 1979 Costs in this puff-ication generally are based on July 1978 costs for the 48 contiguous states. These costs were updated to reflect cur- rent conditions for the Anchorage area. Additional allowances included escalation to 1982, financing during construction, and bonding fees. A bond rate of 10. 5 percent and term of 20 years was used to determine annual debt service. Full development of the 70-mgd demand was assumed. The current dollar operating cost was estimated to be 92 mills per kWh. Though this value may be high compared to current costs, it may be attractive over the life of the project. Because of this cost, an additional larger capacity turbine was not considered because power costs would be even higher. During the beginning years of the project, the water supply demand on the reservoir would be significantly less than 108 cfs (70 mgd). The reservoir could be operated with higher down- stream releases to gain additional hydroelectric benefits during the initial years of the project. Then, hydroelectric output could be adjusted as the water supply demand grows. An additional benefit of maintaining a higher reservoir elevation would be the reduction of summer pumping requirements for the water supply transmission main intake at the reservoir. Additional constant flow for generation would be available if final water supply design calls for release of the reservoir water to the river so that it can be pumped from a location below the Glenn Highway bridges. These additional benefits are not included in this investigation of hydroelectric potential. The major disadvantage of operating with the design minimum res- ervoir level at spillway crest is that the sediment-laden flows would not be passed through the reservoir. Because the effects of an increased pool level during the summer months cannot be evaluated without further sediment studies based on field data, and the hydroelectric benefits appear to be marginal, the hydro- electric development is not included in the project cost estimate 3-21 (Chapter 9). However, the preliminary design of the project allows for future use of one of the low-level conduits as a pen- stock. Stoplog slots are provided at the upstream and down- stream ends of the conduits to allow dewatering and modifications for installation of a hydroelectric plant. These modifications could be made without interrupting the water supply to the Municipality of Anchorage. A life cycle benefit/cost analysis should be per- formed for hydroelectric generation prior to final design. Depending on power cost increase projections, this facility may or may not yield long-term benefits. 3-22 nwo d Pal" Fit fle, Lak iott@ C K N I K LaU -v, Un3 @V' e Sere mil EM ft K@Tik Lake.-', RR V- V Vl- 6A B, V _j @,Cll LAKFV PAHK' Bay.,:@ Aw@d el 6A o 'Pie 0, "4@ 0, @o A Carin:' pointIA) gj. Sj W 'y Ft Richarcfi;wH@,. _a, I ..b K- M R R ,yv ga < % PE P4 ca .7 "tLa L Q Xdw a .... . . .... in a J, J 'W. K v ley. 1,1 iw -0 4000- ,V-0, .0 e BOUNDARY T-41 rn 0 To r5l Ark, o MAX. INST. FLOW, SEPT IS z $240 cf# 4000 MAX. DAI ILY FLOW, SEPT IS m 4900 efe 4000 MAX. INST. FLOW. AUG 8 z 3650 0. M AX. DAILY FLOW, AUG 8 3600 cf. 3000 3000 2000 2000 1000 1 1%1.11000 MEAN DISCHARGE 709 .1f. M ARGE, 608 0. V 0 MA _.T._.@. -A-UZ 30 -DAY LOW FLOW 30 cfa O_ 1986 1967 LrI 4000 4000 MAX. INST. FLOW, JUNE 17 2530 Ct. 3000 MAX. INST. FLOW, AUG 8 Z 12660 .1. MAX. DAILY FLOW. JUNE 1? 2350 t. 3000 200 10- MAX DAILY FLOW, AUG 7 : 12310 CIS 2000 1000 - 1000 MEAN DISCHARGE 485 ft EAN DISCHARGE': 418 0.1 30 -DAY LOW FLOW 60 cla 30- DAY LOW FLOW _- 30cfe 0 1 MAY N OCT I NOV DEC I JAN 11 FEB I III] At OCT I NOV I DEC t JAW I FEB I MAR APR @S- 1968 1969 EAN ISCH - __ __ 0 7- 30- DAY LOW FLOW Z 50.11 OCT NOV E JAN I FEB I WAR I APF SOURCE: USGS Water Resources Data for Alaska Figure 3-2 Eagle River at Eagle River Daily Discharge Hydrographs, 1966-1969 MAX INST FLOW AUG. 9 = 4760 c MAX@ DAIL'y FLOW. AUG. 9 4600 c'$ 4000 - - -4000 3000 - - 3000 MAX, INST. FLOW OCT. 7 3150 cf. 2000 MAX. DAILY FLO IW, OCT. 7 2740 cf. A 2000 1000 1000 MEAN DISCHARGE 457 Cf. MEAN DISCHARGE 478 Cts 30 7, -@'C' -1- _ @AY LOW FL 30 DAY LOW FLOW 36 C"-\ 0 0 -- 1 1 -9- 2F OCT NOV I L)EG I JAN IFER MAR APR JUN LjL -'-TE P OCT I NOV I DEC I JAN I FEB AR 0 a 1970 1971 w 4000 4000 MAX. INST. FLOW, SEPT 13 2700 cft 3000 MAX. DAILY FLOW, SEPT 13 2380 cf. ---3000 MAX. INST. FLO AUG 22 2670 cts MAX- OA ILY FLOWW.AUG 22 2440 cf* 2000 - 2000 -1000 MEAt DLSCtAItGE.F MI AN DISCHARGE 394 Cf. 30 DAY LOW FLOW 33 A7L LEW 0 1 1-i CL@ 0 O'T I NOV[ DECIJAN IFEBI APR I MAY JU JUI MAR MAY JUN JUL AUG I RFP L 1972 1973 SOURCE: USGS Water Resources Data for Alaska Figure 3-3 Eagle River at Eagle River Daily Discharge Hydrographs, 1970-1973 4000 4000 MAX. INST. FLOW, AUG 30 MAX FLOW, JULY I 1 27 10 cfS 2920 cfe M @ INSTY 3000 - -MAX, DAILY FLOW. AUG 30 z 2810 0 A DAIL FLOW, JULY 12 =.2590 cf. 3000 2000 - 2000 1000 1000 __!IE@N @ISCIHALG MEAN DISCHARGE 456 f. - --- - - - - - - - - - - - --- - - - - - 30-DAY LOW FLOW 26 CIS 30-GAYFLOW -@44 @Fr..@AR L 0 ZU I DEC I JAN , , I C 0 1 OCT NOV I FEE] I MAR APR MAY JUN JUL AUG OCT@N OEW JAN c" APR MAY JUN JUL AUG _�_E_P 1974 1975 0 MAX. INST. FLOW. AUG 11 : 4060 cft 4 4000 1 MAX. DAILY FLOW. AUG I I = 3190 cfa- 4000 MAX. INST. FLOW, SEPT 22 3090 cts MAX. DAILY FLOW, SEPT 22 3320 cf. 3000 3000 2000 A ml 2000 1000 A MEAN DISCHARGE 86 1000 MEAN DISCHARGE 467 Cts 30-DAY LOW FLOW 44 cis 30-DAY LOW FLOW 59 f.'\ 0 1 OCT I NOV DEC JAN I FEB I MAR 0 1 APR MAY JUN JUL AUG SEP OCT NOV EEB_ MAR MAY JUN --JUL- AUG SEP 1976 1 77 SOURCE: USGS Water Resources Data for Alaska Figure 3-4 Eagle River at Eagle River Daily Discharge Hydrographs, 1974-1977 4000 - 4000 MAX,,I"1T- FLOW. All. 17 3960 cf! INS -FLOW. SEPT. 13 3420 cf$ MAX DAILY FLOW. AUG 17' 37 10 cf. 3000 - MAXX: DAILIY FLOW, IISEPT 13 '3130 cfs@ 3000 2000 - A4 2000 V 1000 Al N a 11000 A ME DISCHARGE EAN.1I.C.A I 5 @-IOAYI LOW FLOW 00, 30-DAY LOW FLOW = 60 cf& 0 1 MAR APR MAY JUN 0 INV IDEC i.JAN FIED OCT :EB I h MAY JUN OCT S" 1978 1979 I.L 4000 4000 MAX. DAILY FL W, ILLY 3 332 3000 -3000 2000 2000 1000 1000 M AN DISCHARGE 644 cf. IV- 3 DAYLOW@FLOW:l 0 0 OCT funv I nFV. IF [email protected]. AUG SEP OCT NOV DEC i JAN FEB MAR APR M f JUN I JUL I AUQ- 1980 SOURCE: USGS Water Resources Data for Alaska Figure 3-5 :J@ULAUI Eagle River at Eagle River Daily Discharge Hydrographs, 1978-1980 3000- 1500 2000. E W 1000 ul cr co 0) 1000. 7777 Soo 0 0 OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP LEGEND HIGH MONTHLY FLOW AVERAGE MONTHLY FLOW LOW MONTHLY FLOW Figure 3-6 Low, Average, and High 3-29 Monthly Flows 4000 3000 Uj 0 2000 I 000@- 0 20 40 so 8-0 100 PERCENT OF TIME FLOWS EQUALLED OR EXCEEDED LEGEND Eagle River (1966-1979) =Ship Creek (1966-1979) Figure 3-7 Daily Flow 3-30 Duration Curves 200 200 10 20 50 100 Recurrence Interval, Years 100 100 90 go so Ila so 70 70 Based on 200 Years of 60 ynthesized Flow Data 60 so 50 0 U- 40 40 _j x Z 30 30 z 0 A 2 @: 20 20 0 10 -10 99.9 99 98 95 90 70 so 30 10 5 2 1 .1 LEGEND FREQUENCY OF MINIMUM FLOWS PER 100 YEARS *Historical Low Flows Figure 3-8 Low-Flow Frequency Curve 20 20 2 10 20 50 100 10 0 1 1 1 1 Recurrence lnte,v,l,llears 10 - 10 9 9 0 -8 0 7- LAO 7 6 0 -.90001, U- ';;;;@Based on Regional a Analysis 0 4 -4 0 LL 3- 3 Uj Lu CL CO) -2 1 99.9 99 98 95 90 70 50 30 10 5 1 .1 FREQUENCY OF PEAK FLOWS PER 100 YEARS LEGEND 0 Historical Peak Flows Figure 3-9 Flood Frequency Curve ... ....... ...... E## 260 260 ........ ...... ........ ... .. . ... + Tr -ft- +f+FH+f++t- - + -t- 240 240 k UA�i:-T I + 7 + A+ ,220 . . . . . . . ....... .... .. . . ..... ....... 200 200 z 0 180 .... .. iso 2 I-H > > LU LAJ -j J+ likilil +f-4,-f- J+t- ++ 160 . ..... 160 140 H. . . ..... +44-H+- 120 H! 120 TF 4+4F4+[+ + JUIU +H- .. ...... ....... ... . --- HIP --- 100 H@H FEM +FFI tT; STUDY STATIONS (ft) Figure 3-10 Approximate Flood Profiles Study Mile 0 to 2.7 TT TPT:FP -4H444 4- i i i i Ll, +L PoL V 1 A++ TI-4 ....... ... . . 14++4+ 360 360 444- - + -4+ -1-+ P#@4 I - I A f_1 J+tii- -+ 1 1 -H+ + + + 4++ + 444- + 4++- 1 11 + H-@@t TtU + HHH ++- + +I+. + 340 341D ++- -ii+ + i+ 44@ + +H+ 320 320 ...... +H-- '''Hi -H- 44+ 44+ 1- @4 + -4j+I-+1- +Lfd -+--4- MH + t4:1 @Ai+_4t + 444+-+ 4 1300 F 300 - - - + z z 0 0 + > > w _j 4HII 7E LU 280 _j 280 w Ill T777 -f+f-f I- - 4+144h + + .... ..... .. 260 260 + .. ... .... . 240 .. . .... .... ....... ..... ...... ... ...... . .. . .... ... --240 --- ------- -4 f-,H+ + -JJJ_ I- f 44+ I 111 Tli I I I IIIll -220 ... . .. ---- 1"Mr -220 +Ff+ 4+1+ 4HHH . . . . . . . 4+4+ - 7tt::t ARE _+H ia 44A TIP, wH+ STUDY STATIONS (ft) Figure 3-11 i'Ell @_i Approximate Flood Profiles Study Mile 2.7 to 5.3 4HHWH VT HHHH :PT HiH --4+ +T-4- -+4+f+-1-++@- HH! !-+H4 HHHHH H+H .. . ...... . H." A.380 380 44--+f-H-+@ --H- 1 +F --4444-- ----+-4+-44+-@+- .... 1. 4- 1 IT I I IT 11 +t .. I-- +t+-+.++ 4t t-- -ttttt--Vtt- IT T, -6 360 3 0 +H+ Wat i Hi HHH i+ -++H-- 11 Ill T-TT 11-ill-F-TT- 340 -++@@4+4- --7tt- :ttttt IT 11 1 i: 1 -+H+i4l-- I i--H !ill +4+4 - -4+@ -1.320 i3ZU H 1 114++Fi+ 1 1H -4-- 1 ITT -4+ + z 0 44+@+- - T I1 11 -4+ 4A+ + - 0 > LU LU -j LU 306 TH 14++-- 4;F -TTTT 300- LU - ------- ---- ... ....... ......... .......... IT 91111 280 T I I I'll I PRI1111,280 -+f+ 44++@- - - iiHA IT 260 H :-:4@ -Hill ##4260 --- ---------- *+4#1 + - --- ----- - . ...... I .. ..... I I IT I 240 240 +4 -44+1 +ff+ ... ... I Ill TT -Hlt STUDY STATIONS (11t) H-R Figure 3-12 Approximate Flood Profiles Study Mile 5.3 to 8.0 I I I r T 1 1 1 1 1 1 1 1 1 1 T T- :4 -T I I I I I I I I I I I. IT I @l ... 1.11 H + 7-T-1-tl I f I I 1 1 1 11 1 1-4- 44#1 + + ++ 360 360 41- +i HH i4 . . ..... IT, TI -1 1. 1 1 ++ .... 340 ..... 340 + +[4+ 320 .3 2 0 + +++ - 17r-F@F T -44 4+4 4@ 11 1 300 0 0 `I1 +H+ -f+ -++- 4 LU ...... LU Lu 280 280 LU 44-- ...... .... ....... . ..... . ..... . .... i i i 44- H+ ITT IT. ITT I 1 1. 1. 260 ...... ...... .... . . .... .... 260 I. ...... ....... I I IIIII TI I II + ... .... . ... ...... ... ...... ... +++ .. ... ...... .. ...... ...... . ..... ....... . ..... ... . ... ...... I I I T I I I I I I I I A LtLLLLLL -T I I --4-44+ ##a ---- ...... .. . +4 4.444@ _+-,' 7 +H++H + + t+ 4- . . . . . . . 4- . ....... ....... ...... .. .. ... ....... . ..... ... ... TTI TI II . I II 1 .1 1IT. 11 1 1. 11 11 11 IT 11 1 1 1 ITT,,, IT ill 44- + H- ....... ..... I I I IT I -f+ +H-tt 1H+H ITT.'' T I I -f+ .ITT. I . .I ....... . ..... ........ ......... -44 11, .,,1 11 ITT 1 11 1. 4RH 4+1 1+@l I I ..... .. ..... ...... ...... Tfl# R .-. I .... I.... I . .... ...... 11111P.-Illill ITT.. STUDY STATIONS (ft) Figure 3-13 Approximate Flood Profiles Study Mile 8.0 to 10.6 -4- 4' -'F 1 -4- Vt- - Z IM - til@f + +4 + -f+ +H+r +F + H-44 + -+H+++- -4H++4-4+Hf+- �Hj� - +FH + 44# t +H-t+ 4- +Fi+ �H� - +H4 -4- T _irtf_@ + + _44 1@4 - k i. I -- - ---- --- J )HHHHH - - 44 T TT 4 :r4m 1360 360 tl 44444-@4-@ft_._ ....... !!I HHH! H4444411111 l11:t1V+-M Ill I-IT ''I -T --t T_ 7 T- 4- H IT -1340 340 .-6'U LLI.. L __L it IT 11 1 111 AILET 4flfF TTT TII I t ... ... J+ -4- 320 -+-H4--4+- +H+ Hill --- 4+44:FF + + .... I '--+H-H+ +H+FF-i -H +FF -++H--+f-- +Ht- H'll --44+ 1 +1 11 1 z --- ---- t t - 4- I I +HI 11 Hi + L 4- L', - 0 0 z > Ilk, ''I I., IT IT'll + U.1 T -1 + LU M LU _j 4+_ + + 300 LU --H+4+H+i-I- ---- Hj --- H-H-tf- IT I, -H- __rT_r + ��-H� --- --- -tt- 4@4 11 :44 280 -++--t- 4- TIl ,I I I - I . + ....... I 4-H 280 T Hl- -It -I -H- t .. ...... .. ... MH ++ !!I ITT I L ......... ... t T :W. .. @ I . .. @@ --+H4-_ , 4-@ T IIT TPFF 44-H! 1! 260 4-14+4,- -1+ 41 + la L 4+@ 4+- @T .. ........ ...... .... 4:1 - 7H7H ..... . 4++ttH44i+ 11 #:T1 +f- -I I i I +W tili+ li�HA�- TIJ�ff + + -4- $HS �Lt +H+ :1 I%+ +FRI 31 +H @049 1@@ +FR 4444+ -RTiTF STUDY STATIONS (ft) 41@ IFIH1, + Figure 3-14 Approximate Flood Profiles Study Mile 10.6 to 13.3 +H+ HH 4-44- fM i Bit$ -4+ Q - ------ _4 HH +i- - - 380 HHHH ---380 +1 -1+ + -44-H 11111 H ii ++ - - H+ - 4-@ R H +f- + +4+ +1+ - ++ I I I - +FFFF-- ... ... ...... +Ff+.+ -i+i-F+ +f+ -4+4H4++- - -- : T -Fj* 4-H 360 4+H 360 44 + ... H4.j !H1++-HI-H4-H--i+H+fl-H+fl+Hj-H HH, . . . II 1 11' 1---------- I I t1l 1 1 i I t1, 1 -4+H4+Hl--.. 340 340 A- + + + + - 4- H HHH 320 -+--320 z J -t--t-H - f z 0 :+ 0 4@- J+ + +1-4- 44- -4 4 LU 1 t A- LU -j =44 IllI 44+ . . . . . . . . . . . .+ - ul 300 300 .... . ....... -------- --- Hi+F- + ----------- +[+ I; . . ......... + 2aO :-:,T- 280 -- ---------- +H- i i - tf- F 1+ +f+ +H- 111 H 1H H t I - - - t--- t- T ...... ........ ..... + +H4-1+ 4- H4-4 J+f4+H+t +H+ + - +H.- - 4- +-H -4+4--H-H-4@-4 i+ ..... H�Ht H7E 4+H+.+H+f+ 4- ................... mi@ H4+ STUDY STATIONS (ft) IT M- Figure 3-15 Approximate Flood Profiles Study Mile 13.3 to 15.9 . I I I . I I I I I I I I I I I 1 1 1 1 1 1 1 1 1 1 1 6 1 1 1 1 1 1 1 1 111 1 1 1 1 1 1 -H+ I I IT, + +H+4. 4+1- 4 + Uq# -H- ...... +F4:F +H i f T 4-H+ ...... if 1 tf-f-t-ttt- -t -t 1 1 Hi d! 4: #+1 + R v MUT Ill I I ITT I + +H4+ + ------- TFF .. ... ....... fH+ 400 4+t4+ I -+H+- + .. .... 1 1. + +f+ ITT Ill ... ITTI I I I I ...... + H H if HHH ii, .. .... + Ulf 4w1-- - TMUR H 4+ IT Till ++H 380 4+ 380 + IT "I IIJIIIIT if U-- I z Z +lj-:J- LJ 111. + 44* + 4#4#- IT I +@H +1- 44+1- 1 1 411T ##tt- --FFT v 4# 4+FF if iiii �LL1 Ef� +@+4+i-H .. i-+4:EU 360 360 WIL -@Ir Ar - -k +t- -f-t-- 0 IT IT 1 4. 1 T I -444-++ 1 # - -+- - -- 4 1 0 -4+++ > > LU LU LU 340 T 340 Lu ------ 4+-f --- FF--- IT Hi I I =1 III --- H+-+-++i44+ :11111 ilIlIT I- iT 4--- 44:,TFFF . ...... I �L H-++ I- 4-+ -f-f- +H+H4+1--j- 4+4++ + -1++ +F +F+ -f+ ---44 11 '1 1 I IT, 4# 4 + 320 320 ITT ii I +f4- ig I'll I IT T-1 j- -SU+ I 1. .1 1 TTTl.I + +f+ +I,- + I-JiT 4Tt# --t--Hi+H+i-- +H+fi+-- 4+4+ +f+- if -+i+ +f-+H+i4+4-+ +H+ - +11111 -- ------- r ---rt-rrT-- ---- + . ..... ....... . ..... -.1. 11 '','ITT 4 if ...... HH! HIT if! ---I-[+ -:---H+ +@++4-1 + + iiiii H 4+ +H+- 4 :f+ 4++-H+ Ill Till @1 I ITT ITT,, I I ITT Ill It I -ft 11 IT, H@+ +H + +F +1-- 4-44+i IT Lj- :f7,+f++ !IF E 1111111111111111111111IN! fill V: HHH" STUDY STATIONS (ft) Figure 3-16 Approximate Flood Profiles Study Mile 15.9 to 18.6 A P; V NI W v Wv, t-e @4 V, m & 'WN -0 OVA @q V A A Vy, eo, AA N 4. 1, 'k Inw. ago. A 31 k fffl4i W1 Al P.: % 0 Aj. VIV, V4 IE oil@ 'T. N . 11 AU 'k j4 U91, f 1A oor" Of NOTE: Where Flood Boundaries Overlap, Only the Approx. 100 Yr. Boundary Has Been Shown ko, TY, j, v iN f, 7P 9'@ 1,4 A 11s, 1@7 "I'ly IV M, is, I-N r- j4I vo is, Z.V, I`: g I'd 4' 0 Y. i I Rm'. oso 4 'V@*XN TUL 041. Of 1-4 N FIPIT 'a 011 wr 2,@ 4-1 A A Ali' -10 YR 1- 1 54 J p cq, ll KY % 0, ir @1:1 0 01 A S A.0 1@ m 17. A.. w .. . .. ... .. ai:-- %Ie -,o isq- AF, 17 4A 10, 4 'l 14 -@j ev Af @mq 1w s! .6r, A '14 No it t." Is 't4c, 1@1 "OV-v, 16 @,A A.; If @sp A iNll s 4 1. ilk As F 77 It Al P le, 000; N A' 44, ILI 161- NU 14 t N !w- jo 4t 21P 16 ,e 100 YR. v t R,,. A.7 maw-, IF pt J @A M cir 4v A.@ At L j, , , I% f iLv I Al 4T v N@t , '. , .N . . . @to@ i%% m b dw, fw,, ",,v W4, 0.6 Al n 47 O'OJD' I @4p 4 4A U"- :J4 A.3 0: CO) 0 1000 YR 0 YR OIN t.X QQC 100 YR 13 '0 71 a 299 10001, 41 kk@ "o F No A f Ac! n IP,- 'R,V,g W, 41 7V, k.@. V '44 l4i a t TO w, ink, i. IV . . .... in7, e@ 11.@ 1@ ell Av% wl yl@ 4A ee 4 'k r, 25 i 'P @F, S" ol 1% A IQ! 70 w': 04 OF" rri A ;jA V4 or V1 e@ A @5. F I 5 -3 . qq@ 3" v k J. .0 060, 2000' 1000' 4'. AN mg ni, . . . . .... .. \-Wop- Ell Au ic Az ;F4 A lood. ADO -100W4 IVER cm 17 is z kfn- 0 1000, tood, 2000' pq V,=1000'' -"WWI s:10 Imp koni 0 v, 07 LO LO W-1 c? E cr) Jt CL _Af 4 U. A Z I pk@@ co op Y 7," Rp% '-,vt kON 2 P AW, %,0 o@ A"A 4,; #P 4ft Arj f i LU po", cc V1, gt -A IT e@ .. . .................. ................ .. . % '00 Ag, Y,@ o.L m:)jLv rz 12iO 00 1 Peak - 11,360 cfs 110,000 8000 w 0 cr 6000 w co I 0.1 4000 2000- 0 5 10 15 20 26 30 35 40 TIME hrs Figure 3-25 One-Hour Unit Hydrograph 0 z Peak Rain = 1.70 In/hr 0 PMP 24 hr Rain = 11.6 In PEAK FLOW=100,100 cfs VOLUME=134,000 Ac-Ft I= 2 Ui 80,000- Ui (D cc 60.000- 00, to LU 40,000 20,000 0. 0 10 20 30 40 50 so 70 so LEGEND TIME (hrs) wflaw Curve Outflow Curve Ll Figure 3-26 PIVIF Inflow and Routed Outflow 10,000 Aw, I 8,000 01 0,000 IV ;-01F ;-0 00 4,000 1 -00,1 0or I -el I 2.000 or .00.1 -100 00 1.000 800 @00' LIJ (3 600 cr 00, dc X 400 11@-; I I I ILI I I Fr-1 I- -1,-1 11 1 1 1 1 1 1 1 111 1 1 1 1 1 1 1 1 11 200 I L10 Ln 100 001 so- I 00a 60, 40- 4' 20 10 -- - 1 2 4 6 a 10 2 4 6 8 100 2 4 6 a 1,000 2 4 6 810,000 2 4 6 8 100,000 SUSPENDED SEDIMENT LOAD ( ton/day DATA SOURCE: U.S. Army Corps of Engineers. 1979. Figure 3-27 Eagle River at Eagle River Suspended Sediment Load 1966-1972 APPROXIMATE SETTLING VELOCITY IN QUIET WATER at 100 C 10 cm/mo 10 cm/wk 6 cm/day 23 cm/day 4 cm/hr 15 cm/hr 62cm/hr 4cm/min 16cm/min 1 cm/sec: 3 cm/sec 7 cm/sec 15 cm/sec (4 In/mo) (4 in/wk) (16in/wk) (91n1day) (3ft/day) (6 In/hr) (2 ft/hr) (S It/hr) (6 In/min) (2 ft/min) is ft/min) (3 In/sec) (6 In/sec) CLAY SILT SAND very I Ins f Ins I medium coarse very fine fine I medium coarse very firm fine medium I coarse PARTICLE DIAMETER (microns) 100 .5 1 5 10 50 100 1000 0@1 -I , 0 90 10 10 '00000, A 80 00 ;40 70 9,/19/67 000 CO) cc 40 Im w 60 Z 9/21 67 0 9/1,5/,69, PF P, 0, 0 50 . . . Z 7/14/71 Z LLI LU 0 - f I - [ I @0 0 w 8/17/67 Ind @@o "-I Zr Ir LU 40 LU IL 1 .1 1 1 9/14/71 30 001 ooo, 400, 9 /1 3/ 66 ili;'@,68 -- @;--w 6/19/7i i/31/712 1--*- 1-10 10 5/27/69 0 -- 100 0.0005 0.001 0.01 0.05 0.1 .5 1 PARTICLE DIAMETER (millimeters) o 7 i DATA SOURCE: U.S. Army Corps f Engineers. 19 9. Figure 3-28 d IT@ Eagle River at Eagle River Sediment Size Analysis 1966-1972 AREA ( acres) 3600 3300 3000 2700 2400 2100 1800 1500 1200 900 600 300 0 360 - - U 350-- C4 340--Reserv@ir Elevati@n 338 ft I Owl- 33 320-- z 0 310- > LU -i j C@: W 300 0. N U) 290 280 270. 260- 0 10.000 20,000 30.000 40,000 so, 00 60,000 70.000 80,000 90,000 100.000 110,000 120.000 CAPACITY ( ac-ft LEGEND Figure 3-29 Area Lower Damsite Capacity Area/Capacity Curves 360- 360- NOMINAL TOP OF DAM ELEV. 3SO 340- z > LU Ui 330-- cc W co W 00 320- 310- F SPILLWAY CREST ELEVATIO.N 308 300 f i i 0 10,000 20,000 30.000 40.000 DISCHARGE. cft NOTE: d Gate Opening, ft. Figure 3-30 Spillway Rating Curve For a 30-Foot-Wide Gate 320- 316- 310 SPILLWAY ELEV. 308 305- z 0 > 300- W _j LU 295 W m 290- 285- SUBMERGE ID ENTRANCE I OPEN ENTRANCE 280- - 27 - 0 560 1000 1600 2000 2500 3000 DISCHARGE cfS Figure 3-31 Low-Level Outlet Works 3-69 Rating Curve for Conduit HEAD LOSS ft m I I 1 0 CP 4PbQ M Z ol rn m m MINIMUM FISH FLOW 3 -c-f s- G) m 14 0-4 0 0 c" 05' (a R to (D (D 0 'c W (D 0 (D c --ft N 0 q FISH FLOW PLUS MAXIMUM 115SH 1, log MUNICIPAL DEMAND, 139 cfs co U) 295 2901 285 z 0 280 W /Oor 27 270 265 10 210 310 410 510 610 70 810 910 DISCHARGE (1000 cfs Figure 3-33 Lower Damsite Tailwater Rating Curve No Cha pter 4 ON GEOLOGY REGIONAL GEOLOGY The E:agle River damsite is located near the boundary of two major physiographic and geologic provinces: the Chugach Moun- tains surround it to the east, north, and south; and the Knik Arm of the Cook Inlet-Susitna Lowland is located just to the west. Strictly speaking, the site is within the Chugach Mountains. However, the base level established for the Eagle River by the nearby Knik Arm, as well as the glacial history of that area, have profoundly influenced the geologic history of the Eagle River Valley near the damsite. Major geologic units in this area range in age from Permian to Quaternary (Clark, 1972; Schmoll and Dobrovolny, 1972; Zenone et al., 1974). These include older metamorphic and igneous rocks of Mesozoic and Paleozoic age (100 to 270 million years old), Tertiary sedimentary rocks (26 to 38 million years old), and Quaternary glacial and alluvial sediments (less than 2 million years old) The Quaternary glacial and alluvial sediments are discussed in the section Local Geology later in this chapter. The 'Tertiary rocks belong to the Kenai group and are probably of Oligocene age (22.5 to 35 million years old). The tertiary rocks are separated from the older Mesozoic metamorphic rocks by the Knik Fault, a steeply-dipping-to-nearly-verticaI fault that also divides the Cook Inlet Lowland from the Chugach Mountains. Pa- leozoic and Mesozoic rocks include the Jurassic (up to 190 million years old) to Cretaceous (up to 136 million years old) age Valdez and McHugh Groups, as well as older igneous and undifferentiated metamorphic rocks. The Valdez group is separated from the McHugh group by the Eagle River Thrust Fault, located several kilometers east of the Knik Fault. These geologic units and their structural features are discussed in the following paragraphs. Undifferentiated Metaplutonic, Metasedimentary, and Metavolcanic R-o-EFs of Paleozoic or Mes0_Zj1C__W6e Theso rocks are of uncertain age, possibly as old as Permian or as young as Jurassic. They outcrop mainly in the area near the mouth of the Eklutna River, but isolated outcrops are present as far south as the Eagle River. The outcrops include metamor- phosed quartz diorite and gabbro, marble, siliceous argillite, metachert, and metasandstone. Typically, the rocks are of greenschist facies and are poorly fossiliferous. 4-1 McHugh Complex Rocks of the McHugh complex are widespread in the project vicinity and probably underlie the damsite (beneath the glacial deposits) . The McHugh complex consists of a metaclastic se- quence and a metavolcanic sequence that are chaotically mixed together. The metaclastic sequence makes up the largest portion of the complex and consists of dark gray or green low grade metaclastic rocks, including siltstone, graywacke, arkose, and conglomeratic sandstone. The metavolcanic portion includes greenstone (basaltic composition), metachert. cherty argillite, and argillite. McHugh rocks are thought to be of late Jurassic to Cretaceous age (Clark, 1972). Valdez Group Rocks of the Valdez group are Jurassic to Cretaceous in age and are exposed over a large area in the Eagle River Valley upstream from the project (as well as elsewhere). Valdez rocks consist mostly of metagraywacke, metasiltstone, and argillite, with minor metaconglomerate. They are notably unfossiliferous and, gen- erally, of lower greenschist facies metamorphic grade (Clark, 1972). Igneous Rocks These rocks include ultramafic, gabbroic, and felsic plutonic rocks that generally are late Paleozoic to Cretaceous in age. They mainly outcrop in the mountains southwest of the town of Eklutna, but isolated outcrops are also present in the project vicinity. Sedimentary Rocks, Kenai Formation These rocks are of probable Oligocene age and consist of non- marine sandstone, siltstone, and claystone. They are exposed in a few areas along the Eagle River., downstream from the damsite. Structure Two major faults, the Knik Fault and the Eagle River Thrust Fault, divide the area into three tectonic blocks. Each of these blocks has a distinctive type of internal deformation. Knik Fault. The KnIk Fault is a steeply dipping to vertical se- quence of faults, more properly called a fault zone. Its trace roughly parallels the Chugach Mountain front, where it is buried for much of its length by glacial debris. There is little topo- graphic expression in most places along the fault, and no evi- dence of recent activity has been recorded. The fault is located about 2 miles west of the damsite. 4-2 Eagle River Thrust Fault. The Eagle River Thrust Fault is a com ex zone of im ricate faulting that has moved McHugh com- plex rocks on top of younger Valdez group rocks along a low- angle fault. The Eagle River thrust is cut by local high-angle faults In many areas. No evidence of recent activity on the Eagle River thrust or associated high-angle faults has been recorded. The fault is located about 2 miles east of the damsite. Deformation in Rocks West of the Knik Fault. Rocks In this block are characterized by well-developed schi sity and tight small- scale folding. Schistosity generally trends northeast with mod- erate to steep dips. Deformation in the McHugh Complex Block. The McHugh complex rocks 71-e-6-etween the Knik and Ea--gre-Wiver Faults. These rocks have been affected by at least two generations of extensive, close[,-@ spaced shear fractures. The older set dips steeply and generally trends north-northeastf while the younger set has low dips with no distinct trend in folds. Deformation in the Valdez Group. Valdez group rocks are ex- posed west of the Eagle River Thrust Fault. Deformation in the Valdez rocks is characterized by tight similar folds, slaty cleav- age that runs approximately parallel to axial planes, and by numerous high- and low-angle faults. Folds trend generally north-northeast and have steeply dipping axial surfaces. Tectonic Interpretation According to the plate tectonics model, the convergence of the Pacific Oceanic plate with the North American Continental plate has resulted in the metamorphism, deformation, and accretion of portions of the oceanic plate onto the continent. The older metarriorphic rocks located north and west of the Knik Fault are thought to be part of former oceanic coast that was accreted to the continent during Late Triassic or Early Jurassic time (180 to 150 million years ago). The ultramafic rocks, gabbros, meta- basalts, and metacherts are characteristic of an ophiolite se- quence, representing oceanic crust. The Jurassic plutonic rocks, which have intruded them, are often associated with such accre- tionary events. The metaclastic rocks of the McHugh complex were probably orig- inally, deposited on oceanic crust, but derived from a rapidly eroding island arc system located inside the plate boundary on continental crust. The metavolcanic portions appear to have been oceanic crust. These materials were metamorphosed and accreted to the continent some time in the mid-Jurassic (140 million years ago). 4-3 Valdez group rocks appear to represent deep-water marine tur- bidites that were deposited on oceanic crust during the Creta- ceous age. These rocks were deformed and accreted to the continent at the same time or just after the McHugh complex rocks were accreted. A more detailed discussion of regional tectonics and faulting is presented in Exhibit C. LOCAL GEOLOGY The Eagle River Valley contains a complex assemblage of bedrock, glacial, alluvial, and colluvial materials. The bedrock units have been discussed previously. The glacial, alluvial, and colluvial deposits encountered during the exploration of the damsite and immediate vicinity all formed during Pleistocene time (within the last one million years). They have a complex interrelationship that has resulted from the interaction of depositional and erosional processes. The best way to understand the geologic history and existing geology of the damsite area is to look at the site's geo- logic features in terms of the processes that have formed them. Discussion of these processes is beyond the scope of this report; however, it may be helpful for those looking at the geologic maps or visiting the site to view the geology as having originated from the following processes: Erosion: By glacial ice and stream waters Transport: By glacial ice, stream waters, or under the in- fluence of gravity (without water) Deposition: From glacial ice, lakes and ponds, and streams and from downslope slumping or creep (variety of mass- wasting processes) Weathering: Chiefly disintegration by ice-wedging and TrFeeze-thaw processes, with minor oxidation and hydration Geologic Mapping The United States Geological Survey (Schmoll et al., 1980) has recently published a map showing geologic features in the Eagle River Valley from Glenn Highway to the upper end of the reser- voir area. We have extracted pertinent sections of that map for inclusion in this report (Figure 4-1 and Table 4-1). The original scale of this map is 1:25000. CH2M HILL geologists mapped the damsite area in more detail (1:1200) during the week of April 12, 1981. This map (Figure 4-2), should be viewed as preliminary and subject to revi- sion and addition of detail during design. 4-4 TOWN OF 4k EAGLE RIVER a qa rl Qcb to ?@YA EAGLE RIVER THRUSTFAIJI-7 qQ9 KNI AU ag qd, I pi r- F A n -k I veb QW4 b 24 WY17 b(q 13 4. WK - I ',@: ZOO 4M it, QDP Zk, ui@ 29 t3 tb wit 4C 00 A: PROPOSED M DAMSITE it QM It it F -- -- -------- ....... . 1000 0 1000 2000 3000 4000 5000 FEET NOTES: 1. Geology Taken from USGS Open File Report 80-890, Plate 1 by H.R. Schmoll, E. Dobrovolny, & C.A. Gardner. 2. See Table 4-1 for Description of Geologic Units. Table 4-1 LEGEND FOR MAP UNITS IN FIGURE 4-1 Alluvial Deposits Qala: Alluvium in active flood plain: sand, gravel, and cobbles Qal: Alluvium in lowest terraces: sand, gravel, and cobbles Qalo: Older alluvium on higher terraces: sand, gravel, and cobbles . Qag: Alluvium deposited in c hannels and fans during the waning phases of glaciation: chiefly sand and gravel Qaf: Alluvial fan deposits formed where streams enter the main valley: sand and gravel Qac: Alluvial cone deposits formed where small tributaries enter the valley and abruptly decrease in gradient: sand and gravel . Qaco: Older alluvial: cone deposits, graded to a higher base level than at present--sand and gravel Glacial Deposits QmIf: Lateral and terminal moraine inferred to be equivalent in age to the moraine near Fort Richardson: chiefly diamicton (till) Qmg: Ground moraine: chiefly composed of diamicton (till) Qmm: Ground and lateral moraine that appears to have been modified by contact with glacial lakes Note: The information in this index was derived entirely from USGS Open File Report 80-890 (1980) by Henry S. Schmoll, Ernest Dobrovolny, and Cynthia A. Gardner. Omissions in this index are the responsibility of CH2M HILL. For more complete descriptions, see Open File Report 80-890. 4-7 Table 4-1 (Continued) Glaclo-Alluvial, Lacustrine, and Deltaic Deposits Q kt: Kame terrace deposits formed in tributary valleys blocked by glacier ice in the main valley: sand and gravel Qk: Kame and related ice-contact deposits laid down in or around glacial ice: sand and gravel Qgl 3. Glaciolacustrine deposits: chiefly silt, Qg1 2' clay, and very fine sand: subscripts indicate dif- Qgli 1 ferent episodes from 1 (oldest) to 3 (youngest) Qgd 3 Delta deposits formed marginal to former lakes in Qgd 2 Eagle River Valley: chiefly sand and gravel: sub- Qgd 1 scripts indicate different episodes from 1 (oldest) to 3 (youngest) Pond Deposits Qp: Postglacial pond deposits: clay, silt, and peat Qi: Interglacial pond deposits: chiefly silt and clay: generally only a few meters in thickness Colluvial Deposits Qca: Colluvial: alluvial mixed material derived from weathering of bedrock upslope and moved primarily by gravity, with minor transport by water Qcg: Mixed colluvium and glacial deposits: similar to Qca, but includes morainal deposits Qcb: Colluvium developed in surficial deposits on river bluffs and canyon walls: chiefly diamicton with interlayers of finer material. Qcbp: Areas of poorly defined bluffs where fine grained material has slumped to obscure the morphology of the bluffs 4-8 Table 4-1 (Continued) Landslide Deposits, Generally Consisting of Diamicton Qcl: Rapidly emplaced by debris avalanching Qcle: Emplaced slowly by earth flow QcIb: Large masses of bedrock that have moved downslope intact QcII: Landslide debris-- possibly modified by lacustrine erosion and deposition QcId: Landslide debris on subdued terrain, possibly modified by lacustrine and deltaic processes Qcs: Solifluction deposits formed by downslope creep Anthropogenic Deposits Qmf: Engineering highway fills Qma: Area altered by man--southwest of proposed damsite includes sanitary landfill Bedrock Units Tkt: Tyonek formation (Miocene and Oligocene): chiefly nonmarine sandstone, siltstone, and coal KJv: Valdez group (Cretaceous): chiefly argillite, siltite, and meta graywacke KJm: McHugh complex (Cretaceous and/or Upper Jurassic): chiefly massive, weakly metamorphosed sandstone and conglomeratic sandstone with minor metavolcanic rocks J Pu: Igneous rocks (Jurassic to Permean): chiefly gabbro 4-9 ,x el 421 0 <-7 -,Qal Qala@' N@' ......... .... --- -- ----- QgI g,\ Q . N, @A gI, QaIa Qc", B@4, .,Qag COI N Qaq Q_qI ------------ B-31, C.) Qr VI\ 3@@I) 0 @a\ X N,\ 4 5 7. 0'. cr, Oalo Q 1 110 6\@j al X X' 2 7.3 '3 /X, V QaI QaIa cob le 84 QaIa ....... . .. .... C.. 283,5 Ogi ... ....... OgI . . ........ -------------------- 30cj QgI A 411 0 Geolog c Units This section describes the geologic units that were encountered during our exploration of the damsite and surrounding vicinity (approximately a one-half-mile radius). They are described in their general chronological order, starting with the oldest first. Chronologically and spatially, many units overlap and grade from one to another; therefore, their sequence is a generalization. The s) ,(mbols given with each unit's description (e.g., QmIf) are those used in Figure 4-2. Lateral Moraine (Qmlf). These deposits are chiefly till or diamic- ton (mixtures of all size particles) formed as lateral moraine and located on the south valley side above the proposed damsite. Schmoll et al. (1980) infer that they are equivalent in age to the lateral moraines in the Fort Richardson area. Ground Moraine (Qmg). Equivalent in age to the lateral moraine deposits, this ma_t_e_rT5T was probably laid down beneath the glacier or is an ablation deposit formed during the glacial recession. In the project vicinity these deposits were observed to be a coarse diamicton (till) that is well-graded from fine sand to 12-inch boulders, contains little silt or clay (tested at 2.5 percent), and is very dense. These ground moraine deposits show a very faint degree of stratification. The left dam abutment is partially com- posed of this unit. The ridge west of the damsite and the upper valley north of the damsite contain large deposits of ground moraine. Outwash Sand and Gravel (Qag). These deposits overlie the ground morain material located in the left abutment (downstream side) and thus are thought to be younger. This relationship is clearly, shown in the high river cutbank at the left abutment. The deposits consist of well-graded fine or medium sand up to coarse gravel. They contain only about 5 percent material that is larger than 4 inches in diameter and about 2 percent silt and clay fraction. They show sufficient stratification to indicate that they were deposited by flowing water and were probably formed in channels or alluvial fans during the waning phases of glaciation (Schmoll et al., 1980). The hillside downstream on the left side contains a considerable amount of this material. Glaciolacustrine Deposits (Qgl). These deposits consist of 'silt, clayey silt, and sandy silt, or clay, as noted in the laboratory test results of materials from borings B-5 and B-6 (Chapter 5) and from borrow sample 11SU (Exhibits D and E). They contain slight to pronounced stratification, with layers ranging from 1/4 inch to several inches in thickness. Some layers are nearly all fine sand, while others have no sand. They formed in glacial lakes that developed as a consequence of the valley outlet chan- nels being dammed downstream, probably by glacial ice. These glacial lake deposits are extensive in the damsite vicinity, both 4-13 northeast and south of the site, as well as partially beneath it. Information from our borings indicates this material is present be- neath the entire right side, center, and at least on the upstream half of the left -side of the dam. Throughout the valley, three different episodes of lacustrine deposition have been mapped; however, the deposits near the damsite appear to be all of the second episode. Some third-episode deposits may be present be- neath alluvial deposits on the low river terraces in the reservoir. Older Alluvial Deposits (Qalo). Older alluvial deposits are younger than the lake deposits because they are present in eroded areas of former lake deposits and overlie these lake depos- its. They generally consist of slightly stratified well-graded sand and gravel, and probably represent channel fill. They are pres- ent in the right abutment and spillway areas, as well as several locations upstream and downstream. Generally, they are higher and thicker than the younger alluvial deposits. Older Colluvial Deposits (Qco). These materials are derived from nearby glacial or alluvial deFosits and form wedge-shaped deposits downhill, moving chiefly under the force of gravity and without running water. They are present along many slopes in the dam- site vicinity, notably in the left abutment (upstream portion) and along the north side of the valley that joins the main Eagle River Valley just above the damsite, essentially mantling the left abut- ment upstream. They have been observed to be variable in com- position from rather dirty diamicton to poorly graded sand, gravel, or clay, depending largely on their source. Because these deposits are older, they are well-vegetated and show very slow movement at the present time. Pond Deposits (Qp). Pond deposits are present at several loca- tions near the d site, including overlying the left abutment's glacial deposits. They are similar in composition and stratification to glacial lake materials, but younger and confined to local envi- ronments. They are generally thin (3 to 10 feet thick) and usu- ally show contorted bedding, indicating that they are ice-contact deposits. Younger Alluvial Deposits (Qal). These deposits are similar in nature to the older alluvial a-eposits, but are younger and gener- ally within the river's present floodplain. They are stabilized by moderate to extensive vegetation and are located in gravel point bars and channel fills. Active Colluvial Deposits (Qcb). These are deposits that are presently forming under the influence of gravity along the base of moderate to steep slopes. Most notable of these deposits in the damsite vicinity is the large colluvial wedge at the base of the river cutbank along the entire left abutment. Freeze-thaw cycles cause loosening of ground moraine, outwash gravel, and older 4-14 colluvial materials in this cutbank. These cycles allow gravity to move the material downslope, forming the characteristic wedge shape. Recent Alluvium (Qala). These are materials actively transported U-y-t-Fe-river during p riods of high water. They consist of sand, gravel, and cobbles that form temporary bar and bank deposits. Some sand also moves as streambed traction load, even under normal flows. Recent alluvial deposits generally were observed to have a low percentage of silt and clay fraction because silt and clay tend to stay in suspension. They are. for the most part unvegetated. Generalized Summary of Local Geologic Events Evidence indicates there were one or more very extensive early Pleistocene glacial episodes in the Eagle River Valley. Judging by the location of lateral moraines on the valley sides, these early glaciers must have been up to 2 miles wide and 2,000 to 2,500 feet thick in the project vicinity. Some of the ground moraine depos- its probably originated during these early episodes. Most of the lower moraine deposits probably were the result of later Wisconsin Stage glaciation, which was somewhat less extensive than the ear- liest episodes. Deposits of lateral and ground moraine, and other units, probably filled across most of the valley, at least up to about elevation 650 feet in the area downstream from the damsite. The outlet for the Eagle River was probably along the south side of the valley, through the present tributary valley located up- stream and immediately south and west of the damsite. This allowed the river to flow out somewhere near the Hiland Road- Glenn Highway junction. Periodically, this outlet or other outlets must have been blocked by glacial ice downstream, thus creating the three glacial lakes of which we find evidence today at various levels in the valley. Between these episodes of lacustrine deposition there were contin- ued erc)sIon and perhaps even minor glacial advances and retreats. Erosion and deposition by stream waters alternated and created the different levels of terrace deposits we see today, as well as the meander scars visible in the valley walls. Drainage was established through the existing outlet downstream from the dam- site, lprobably sometime after the second glacial lake formed. Colluvial processes were active from the earliest glacial episodes, and evidence of very old to recent deposits is present. . At the present time the river appears to be actively downcutting, and erosion is.the dominant process in the project vicinity. GEOLOGIC HAZARDS We conducted a preliminary evaluation of geologic hazards to the clamsite and reservoir area. This evaluation was based on air photo interpretation, ground reconnaissance, drilling information, 4-15 and the preliminary seismic evaluation made by our subconsultant Lindvall, Richter & Associates (Exhibit C). The geologic hazards we have addressed include earthquake damage to the dam, fault rupture, landslides, liquefaction, and soil settlement. Earthquake Damage to the Dam Damage to the dam embankment caused by seismic shaking is a possibility. According to the preliminary seismic evaluation (Ex- hibit C), the dam should be designed for a peak acceleration of 0.4g and an effective peak acceleration of 0.33g. Measures to mitigate potential earthquake damage to the dam and appurtenant structures are discussed in Chapter 8. Fault Rupture Our exploration did not reveal the presence of any faults, either active or inactive, underlying the damsite. The Eagle River Thrust Fault, considered inactive, crosses the proposed reservoir site about 1 to 2 miles east of the damsite. We know of no evi- dence to indicate that this fault or any other fault presents a surface rupture hazard to the damsite. Landslides There are two types of potential landslide hazards to the project: earthquake-induced landslides and landslides generated by rapid drawdown of the reservoir. The reservoir area contains very heterogeneous deposits, ranging from fine-grained glacial lake sediments to coarse glacial till and alluvial and colluvial deposits. Some older landslide deposits are also present in the reservoir area. Under saturated conditions, an earthquake might induce a landslide in some of the less consolidated colluvial desposits or cause older landslides to move. Lacustrine deposits (fine- grained) might become unstable under rapid drawdown conditions; the effects of a lacustrine deposit landslide on the damsite would depend on the slide's location, volume, and rate of entry into the reservoir. A study of the stability of various deposits in the reservoir area is beyond the scope of work for this project. A stability evaluation should be made during final design to assure that the dam and reservoir would have an adequate margin of safety to handle potential landslide problems. Earthquake- Induced Liquefaction or Settlement Liquefaction and failure of soils as a result of seismic shaking generally requires three elements: (1) sufficiently high, repeated ground accelerations, (2) soil saturation, and (3) fine sandy or silty soil that is not highly densified. The level of seismic shak- ing may be high enough at some time during the Eagle River dam's lifetime to cause liquefaction of relatively loose saturated soils. However, the materials to be used for dam construction 4-16 would be highly compacted, which would make liquefaction or settlement of the embankment highly improbable. The very dense condition of the dam's foundation materials would also preclude liquefaction. Settlement from earthquake shaking should also be very unlikely because of the proposed density of the materials. (Further discussion is presented in C,hapter 8.) PREVIOUS GEOLOGIC STUDIES Our review of published literature indicates that a number of pre- vious geologic studies of the Eagle River Valley have been made. The earliest study we found was done by A. F. Bateman in 1948, though not published by the U.S. Geological Survey (USGS) until 1980 (Bateman, 1980). This study is an evaluation of the Eagle River Valley for potential damsite locations. Two potential sites were selected, and a reconnaissance evaluation of the site geologic conditions was made. One of Bateman's sites is nearly the same as the present site, although slightly downstream. In 1974 the USGS published a land use planning report on geology and groundwater in the Eagle River-Chugiak Area (Zenone et al., 1974). This report discusses the area's geology and its impact on urban and groundwater development. An electrical resistivity and seismic refraction survey was conduc- ted by the USGS in 1979 to determine the depth to bedrock in the middle valley area of the Eagle River Valley (above the proposed reservoir). Their study indicated that 350 to 450 feet of uncon- solidated sediments overlie bedrock. They made an additional electrical resistivity sounding in the tributary valley located south of the proposed damsite. Their findings suggest the bed- rock surface is near elevation 50 feet. This tends to confirm that this valley may have once been the major outlet for the Eagle River. Probably most valuable of the available publications is the prelimi- nary geologic map of the middle portion of the valley, published by the USGS in 1980 (Schmoll et al., 1980). This map (see Figure 4-1) provides a detailed breakdown of the valley's complex geology and is accompanied by a thorough description of mapped units. 4-17 Chapter 5 FIELD EXPLORATION FIELD EXPLORATION ACTIVITIES Geotechnical field exploration activities consisted of a geologic reconnaissance of the site, drilling, and surface bulk sampling of materials in river cutbanks. Geologic Reconnaissance An initial geologic reconnaissance of the project site was made at the time of drilling operations (January 1981). Later, during the week of April 12, 1981, a more thorough reconnaissance of the damsite and surrounding area was made, and a geologic map of the clamsite area was prepared. The purpose of this work was to locate potential borrow sources and to look for geologic hazards that could affect the conceptual design of the project. In addition, color and black-and-white aerial photographs taken in September 1979 (Air Photo Tech, Inc., 1979) were used for recon- naissance of a much larger area in the Eagle River Valley. These photographs helped to evaluate the potential geologic hazard to the project and to identify the sequence of geologic events de- scribed in the previous chapter. Drilling Between January 13 and February 11, 1981, six borings were drilled in the vicinity of the proposed dam to acquire subsurface information at the proposed locations of the spillway, inlet tower, and main embankment. The drilling was done by Exploration Suppl,'@ and Equipment, Inc., of Anchorage. They used an Acker MP-4 drill rig mounted on a Nodwell chassis; mud rotary methods were employed. Biodegradable drilling mud "Revert" was used at locations near the river, and bentonite mud was used at other locations. The locations of the borings are shown in Figure 5-1.- The boring logs are shown on Figures 5-2 and 5-3. Drillirg and sampling operations were directed and monitored by a CH2M HILL engineering geologist. Samples were visually classi- fied in approximate accordance with American Society for Testing and Materials, Standard D 2488, "Visual-Manual Procedure for Description of Soils". Selected samples were taken to the labor- atory of Harding-Lawson Associates for classification tests and engineering properties tests. The remaining samples were stored. A piezometer was installed in boring B-6 to monitor ground water in an aquifer encountered at the 54- to 60-foot depth. The piezonieter was made of 314-inch-diameter PVC pipe. The pipe. was capped on the bottom and slotted with a hacksaw at 3-inch 5-1 intervals for the bottom 20 feet. It was surrounded with pea gravel for the bottom 25 feet and sealed with clay for the top 35 feet. A 1/2-inch-diameter steel pipe was installed at the sur- face to help reduce vandalism damage. The piezometer flowed 1 to 2 gpm at the surface. Water would rise to approximately 2 feet above the ground surface when a riser was connected to the top of the piezometer. When the piezometer was checked again in April 1981, flow was continuing at the same rate. Bulk Sampling of_Borrow Materials Much of the potential material for the dam construction is sand, gravel, and cobbles. Samples of this material cannot be properly obtained for testing by drilling. Bulk samples (60 to 100 pounds) must be taken either from river cutbanks or from backhoe test pits. Backhoe excavations were not necessary because of the easy accessibility of most potential borrow materials at the river cutbanks. Initial sampling of representative materials in the river cutbanks was done on February 11, 1981, followed by additional sampling during the week of April 12, 1981. Materials sampled include ground moraine deposits, outwash sand and gravel, older alluvial deposits, recent alluvium, and glaciolacustrine deposits. The laboratory test results in Exhibits D and E provide descriptions of the properties of these materials. SUBSURFACE CONDITIONS The descriptions of subsurface conditions that follow are based on information obtained from our January and February 1981 drilling program, observation of river cutbanks, and from USGS studies of the Eagle River area. Additional field work during design would be required to confirm these findings. Because of the great variability of material types, both laterally and vertically, identified in the area, the descriptions should be considered generalizations, and may not be accurate at all points. Right Abutment (North Side) and Spillway Area The surface in this area is covered by a 1- to 3-foot-thick mat of fibrous peat or muskeg. Coarse sandy cobbly gravel (Unified Soil Classification of GW) is encountered beneath this mat down to approximately elevation 255 or 260. This material contains 2 to 10 percent silty matrix. The geomorphology and material type of this area suggest that, at least near the surface, this material is an older alluvial deposit. Possibly the alluvium changes to a coarse glacial outwash deposit at some intermediate depth, but this has not been confirmed. The sandy cobbly gravel is underlain by approximately 10 feet of clean medium sand (SP), with a top elevation of 255 to 260 feet. 5-2 This sand is interpreted to be an older stream deposit. Below elevation 245 or 250 feet, sandy silt was encountered. This material graded into silt (ML) within 5 to 10 more feet of depth. This silt is bluish-gray, very stiff to hard, and has low plasti- city. Some parts of this layer are predominantly clay (CL). The layer extended past the greatest depth drilled (elevation 222 feet). Occasional thin (1/2-inch to 1-inch) seams of fine sand were found, as well as occasional single cobbles. This material almost certainly is a glacial lake deposit, with the cobbles possibly hav- ing been ice-rafted. A similar sequence of deposits is located in a cutbank several hundred feet downstream from the proposed right abutment and spillwa,'@ location. In that exposure, the slumped and contorted nature of the sand and silt layers suggests that the deposits are ice-contact sediments. Main Embankment (Middle) and Control Tower Area The Surface in 'this area is covered by up to 3 feet of fibrous peat (muskeg) outside the zone of active river erosion; within this zone fresh river alluvial deposits are exposed. These river alluvial deposits also underlie the muskeg and extend down to approximately elevation 260 or 265 feet. This material consists of interlayered mixed silt, sand, gravel, and cobbles. It varies from well-graded to poorly graded (GW/GP) and is unconsolidated. Below the moderately coarse alluvial d eposit, 2 to 5 feet of fine alluvial sand (SP) was encountered. This type of material is also present in a terrace that is about six feet higher than the terrace on which boring B-6 is located. Below the sand, at about eleva- tion 260 or 265 feet, the same layer of silt described in the pre- vious section was encountered. This material extends down to approximately elevation 230. Within that layer, between about elevations 245 and 248 feet, is a 3-foot- thick 'layer of gravel and cobbles. At about elevation 230 feet, there is a gravel and cobble layer, with a clay matrix, about 8 feet thick. This layer contains minor artesian pressure. A piezometer was installed in boring B-6 to monitor the artesian pressure in this layer. This boring reached material that is probably bedrock at elevation 222 feet, and ended at about ele- vation 218 feet. Left Abutment (South Side) The left abutment contains a variety of glacial deposits. As on the right side, the surface is covered by 1 to 3 feet of muskeg. Underiying this is a 5- to 20-foot-thick slumped wedge of sandy 5-3 cobbly silt (thicker toward the upstream side) , probably an ice- contact glacial pond deposit. Underlying this deposit is a till deposit of variable thickness that appears to extend nearly the full height of the proposed embankment at its centerline. This material is a dense, poorly stratified, well-graded sandy cobbly gravel (GW) with only about 2.5 percent material passing the No. 200 standard sieve. This deposit is interpreted to be a glacial ground moraine that has been dissected by the Eagle River. Overlying the till on the downstream side and in partial contact with the left dam abutment is an outwash deposit of stratified silty sandy gravel. This material consists of clean sand and gravel, with only a little material larger than 4 inches in diameter. A wedge of older colluvium is present in the upstream portion of the left abutment and is derived from and transitional to the ground moraine located in the abutment center. Information from boring B-2 indicates that silty sand and gravel extend down to about elevation 260 feet and, below this, sand and gravel, coarse gravel, cobbles, and sand with a silt matrix extend to at least elevation 232 feet. The latter layer appears to correlate with the silt layer identified in the right abutment and mid-embankment areas; however, beneath the left abutment this layer contains considerable amounts of coarse gravel, cobbles, and sand. This fact suggests that the left abutment may overlie the edge of a former glacial lake, where considerable colluvium was deposited along with the lacustrine silts. What is probably bedrock was reached at elevation 232 feet. Bedrock Information from borings B-2 and B-6 suggests that bedrock underlies the damsite at about elevation 220 to 230 feet. A water well was drilled 700 feet southeast of the damsite as a part of 'Task 1 of this study. This well encountered bedrock at eleva- tion 244 feet. These three borings suggest that the bedrock surface dips slightly east of north at about 2 degrees. Rock cuttings from each of the borings were composed of similar mater- ial. The cuttings appeared to be metagraywacke, probably from the McHugh complex. A previous boring drilled by Retherford Associates (1966) north of the dam penetrated 240 feet and did not encounter rock. 5-4 42 1.0 -70 5 A@, - X 21 0 274@5 cD -- - -- -------- ------ - - - - --------- - - ------ ---- ----- .. ... ....... B-4 _b GB-3i.. 417.0 S;o 4 5 7 /X mg U 2 73 45 d AA 28 283 5 . .. ....... ... 4po 42 1 13 El. ;50, R. ;24' It. 3/Z 0- laAMIC rONOIL AJ VJ W p(ar 0 mafiv/c ropoll Vir) 14 41IN NAM ;4,vO 27 44A10Y ver w1al MAW ;/IT WIN 694VEt f, PORE5 55- cOgAlf; t A24vel 1-3 t-. I - - T 694V[IIY VLTV MJI) 13 F5 - W 44YOV coviv 0.4vel 90- 0, 1%11:@. (w4vitly ;4wov ;fir /00 ZO 20 f4AIOV MVII 80 -..1. 0 50 50 - 1,1176E COME;, ;.QAIO S MM 0 -2fivit zz 2 0.... C- 5401V 0 20'- n .0. ;AVOV 4/CTV C UOI[ MVIAI :.,0 60 01: uAffigif TO ORM 044ple'? AUVel, C0991f; f 44#0 Out To C0881 to 50 ..0 Umfigif To Ofllvf 6ampa? 75 40 0, .5fC4U;E OF C0,5811f cx Un :0" C@ 100 50 50 WIN# OR l5ffl,70cle SORIMC AlUAMER x(Ort /Oq 940M OR V11114f 90411/4 cottap 2-4-01 (00 5YUB91; 1#0149rf FLO (01 PE4T fl[V4118AI mmin commrufmr w 'k)l A/0 rE W020 clov AM VII r64T -816w6lFt. r9l MOW rw PIT im 6 actArm mfolimorlam El WkIWAIT flif OPIA1100 Of Tuf WWI;[ 4; ro 70- ;aijoy 611 r* ctav 70 Mf CAWMW Of 1111 hf,411,71,414 V fAtf IOWIPAlf CUT F0--0l COME; 4140WAI 4011, I?Otk, t- PROU90 W4TIR COMOMOA14 FM 100 1 /0001 N[W[Af AviflefAir TW AlOU4 t, Ar OfAlfg 100TIOAl; Pfl m4v DIFfa, fflom fum wwv. Qlaw w4rfe t,. MUR rust WIMC MAIDIWAI; MAV CU4.VPE WIN WE f""p,0644M AUE 9F P4449;E of rimc. 41L 10C,000k; t. REWIOAX VOW ro Pu4m, COMPIM09 4W 4PPROXAMTI. z to- 8 1 -W @-lllwl W- Figure 5-2 Damsite Boring Logs B-1 Through B-3 ft 3/0, ft. Z 7(o' 0 @)l OkUyle rOP40/6 r- OUAIJIC rop5olt t Pidr 0 ptAr Comy ;lLrv ;,wo Lor ..IN ORPUIC rop4olt ECI iy_ 7(9 @T' 1* MIlEtIv ;Itrv MD, (117WIly 41ITY 0A19 W11 I c 6 44dvov 4lay @R,4vel W14 C06YU64 io: Cavilly MIO WITU COOBJE; 10 % 10@ -/0 71- :6-- - MFOIUM 4AA1,9, SECOMINC, f1w A/ma /4 fr, 0, 71 94 4116911Y C94VULY ;AIJD, MOV (44VEIJY 411T 7 WDIUM to flAlf /00/ 70 /(- .0. GAUVE11Y flIN 4RA10 1000 1200 70 0 P41 WIT14 COME; A 31 A I/ raviv va, vf/zv ;rlff /zoo c A ',',/ to Uno, 416ully $aljov P41 Ct4YfY ;Ar, rmff TO A1429 50 A/ /,V 6OA41 Lay,-14. 30 50 ;4mo CH24VII, t- cogglf;, 61aa@ty ;/Lrv 44 Zt 'I. - 06 C098LY 44AIDY rrfl.4V[l 40 --200 50 54 7-7 74'-d.'-@b@ C0,591V 4XIOV AUVEI 40 Ct4VEV ;111, ;OA41 141w; MON UM(fy, QAM L.MV; Of CLMV ;It[, U49D fwE 4awo, iriFf to mago. 50 54 --85- fo MfOlUM 54AID, 60CWTIV C-RAVRIV 5 j24Vfl WlfM Ct4V ;,b Af4fVlJ( - 4RIM&I PRf;Q111 too (70 ;Ilr + f 45 md / +++ soutofe 0/1 80leo" 70 70 AIM ;ff fICURf 37-,?fOl IWAID t A(Orj Figure 5-3 Darnsite Boring Logs B-4 Through B-6 Chapter 6 00 LABORATORY TESTING This chapter briefly describes the laboratory tests that were per- formed on soil samples obtained during the field exploration. The testing is divided into two categories, classification testing and engineering properties testing. - Classification tests were per- formed to broadly categorize the soils ion the basis of their engi- neering properties. These tests included Atterberg limits, nat- ural ;oisture content, grain size analysis, and specific gravity. Engineering properties were determined by triaxial shear test and by unconfined compression, consolidation, and compaction testing. The tests were conducted by both CH2M HILL and Harding-Lawson Associates. The results of the testing performed by Harding- Lawson Associates are presented in Exhibit D, and the CH2M HILL test rESUIts are presented in Exhibit E. A summary of all labora- tory tE!st results is presented in Table 6-1. CLASSIFICATION TESTS Atterberg Limits Atterberg limits were determined according to ASTM D423 and D424 con selected samples. The results are shown in on Plate 3 of Exhibit D and Figure E-1 of Exhibit E. In general, the results of Atterberg limits tests conducted on different samples of a given type of plastic soil will plot in a group generally parallel to the "A-line" shown in the figures. The samples tested for this study fall into two general soil groups. First, a low-plasticity silt that plots just below and par- allel to the A-line; these samples represent the silt found at about 18 feet below the valley bottom. The second soil group is a low- plasticity clay that plots just above and parallel to the A-line; these samples represent a lower, slightly more plastic facies of the low-plasticity glacial deposits beneath the valley bottom. These two groups, while technically classified as different soil types, have been combined for the purpose of analysis because of their proximity to the A-line and their similar characteristics. Natural Moisture Content Natural moisture content determinations of a number of soil sam- ples Yvere made according to ASTM D2216. The moisture content of the soil would fluctuate with the seasons, so these results may not be representative of the moisture content during construction. 6-1 Table 6-1 EAGLE RIVER DAM PROJE& SUMMARY OF LABORATORY SOIL TESTS Effective Natural Percent Internal Water Liquid Plastic Passing Sh - ear Angle of Sam 9] e Depth Visual Unified Soil Content Limit Limit Plasticity No. 200 Specific Str4ength Friction Comp. No. (ft) Description Classification M M M Index Sieve Gravity (P sf) (deg) Index B-1 SS-1&2 b 5& 10 Sandy Silt M L 7 92.5 B-2 SS-I 5 Sandy Silt NIL 26 - - - 82.5 B-3 SS-12 85 Sandy Silt ML 30 39 26 13 - B-4 SS-7, 8, &9 b 39,40,&45 Silty Gravelly Sand SP-Sm 12 - - - 9.0 B-5 SS-1&2 b 5 & 10 Silty Gravelly Sand SP-Sm 15 - - - 8.0 - - - B-5 ST-1 20 Silt MIL 24 33 26 7 99.8 2.75 - 38 .05 B-5 SS-4 25 Silt NIL 27 41 27 14 - - 1230 - - B-5 SS-5 30 Silt NIL 32 - - - - - 2520 B-5 SS-6 35 Silt NIL 28 - - - 96.5 - - B-5 SS-8 45 Clay CIL 22 36 21 15 - B-6 SS-1,2,63 b 5,10,&15 Silty Gravelly Sand SP-Sm 14 - - - 9.5 - - - - B-6 ST-1 20 Silt MIL 22 - - NP c 99.9 2.72 - 42 .04 B-6 ST-2 25 Silt NIL 26 39 27 12 99.6 2.74 - 38 .07 B-6 SS-4 30 Silt MIL 29 49 28 21 - - 4300 - - B-6 SS-5 40 Clay CIL 25 36 22 14 - - 4530 1W 0 Sandy Gravel GW - - - - 2.5 - - 1E 0 Sandy Gravel GW 2.9 - aBoring and sample numbers, except IIE and 1W which are bulk samples (see Figure 5-1 for location). bCombined. cNonplastic. Note: SS = split spoon sample. ST = seamless steel tube sample. Grain Size Analyses Grain size analyses were performed on selected soil samples to aid in soil classification and to provide information that can be used to estimate soil permeability. These analyses were done by me- chanical (ASTM C136) and hydrometer (ASTM D422) methods. Additional samples were also tested in accordance with ASTM C117 to determine the percent passing the No. 200 sieve. A summary of the grain-size analyses is shown in Plates 2 and 18 of Exhibit D. Specific Gravity The specific gravity of solids for selected samples was determined according to ASTM D854. These values were used in computations for engineering properties tests. ENGINEERING PROPERTIES TESTS Triaxial Shear Test Consolidated-und rained triaxial shear tests with pore pressure measurements were performed according to ASTM D2850 to provide an estimate of the effective stress behavior of the soil. This was necessary for evaluation of foundation and slope stability. The tests were performed on samples obtained by means of a thin-wall tube sampler. The effective stress envelope was computed at the maximum effective principal stress ratio. Because the theoretical effective cohesion of a nonplastic to slightly plastic silt is ap- proximately zero, the design effective stress cohesion was as- sumed to be zero. This indicates an effective stress angle of in- ternal friction of 42 degrees for the nonplastic silt and 38 degrees for the slightly plastic silt. The results of the triaxial shear tests are shown in Plates 13 to 16 of Exhibit D. Unconfined Compression Test Unconfined compression tests were conducted according to ASTM D2166 to provide strength data for slope stability analysis. These tests were performed on disturbed samples obtained by means of a split-spoon sampler. The maximum value of axial stress from the axial stress versus axial strain curve was taken as the unconfined compressive strength. The undrained shear strength was approx- imated as one-half of the unconfined compressive strength. The results of these tests are shown in Plate 17 of Exhibit D and in Figures E-2 and E-3 of Exhibit E. Consolidation Tests Consolidation tests were performed according to ASTM D2435 on relatively undisturbed samples of the silt layer to provide an 6-3 estimate of the compressibility of the soil. Samples were obtained by means of a thin-wall tube sampler. The results of these tests are shown in Plates 4 to 12 of Exhibit D. Compaction Tests Compaction tests were performed according to ASTM D1557 on samples of borrow materials to determine the maximum dry density and the optimum water content. The results of these tests are shown in Plate 17 of Exhibit D. 6-4 Chapter 7 E14VIRONMENTAL CONSIDERATIONS IDENTIFICATION OF ENVIRONMENTAL CONCERNS Some of the potential environmental impacts of a dam on the Eagle River were discussed in the MAUS report (1979). These poten- tial impacts include: � Physical impacts - Air pollution - Noise Pollution - Water quality � Biological impacts - Vegetation - Fish - Birds - Mammals � Socio-economic impacts - Historical and archeological sites - Land use - Recreation AWSU requested identification of the environmental concerns that may be related to the development of a water supply reservoir on the Eagle River. To accomplish this, CH2M HILL personnel met with Municipality of Anchorage, State of Alaska, Federal, and Eklutna, Inc., personnel during the week of February 2, 1981. These meetings were held with people from single agencies or small groups of agencies with related interests. The following agencies and organizations were contacted: 0 Federal Agencies Department of the Army: Corps of Engineers; Fort Richardso mmand, Environmental Office and Utilities Division Department of Commerce: National Marine Fisheries Service Department of Interior: U.S. Fish and Wildlife Service U.S. Environmental Protection Agency 7-1 0 State of Alaska Department of Environmental Conservation Department of Fish and Game Department of Natural Resources: Division of Forest, Land and Water Management; vision of Geological and Geographic Surveys; Division of Parks 0 Municipality of Anchorage: Planning Department 0 Eklutna, Inc. We did not attempt to establish priorities for the environmental concerns that were expressed, but we believe that the common expression of a particular concern indicates that the concern is relatively important. The per5on5 contacted expressed concern over adverse effects on natural resources, on the human environment, and on the visual or aesthetic quality of the area. The most commonly expressed concerns were over effects of the proposed project on fisheries and water quality. Adverse effects on water quality could poten- tially affect both fisheries and human health. Our results are not conclusive because some groups, such as representative residents of the Eagle River Valley, were not con- tacted. Such a group might have serious reservations about the visual impact of the project. ENVIRONMENTAL CONCERNS Fisheries The extent of the fisheries resources in the Eagle River is not well known. The persons contacted indicated that the existing resources should be identified and protected. Several specific issues were raised concerning fisheries resources. Studies would be required to determine the extent of the fisheries resources. Loss of Habitat As a result of the proposed project, the known spawning area at the mouth of the South Fork of the Eagle River would be inun- dated during the winter, probably resulting in the smothering of any eggs deposited there. The main channel of the Eagle River in the reservoir area is not thought to be heavily used by spawn- ing salmon, but some losses may occur there also. 7-2 Fish Passage Facilities Salmon are known to spawn in the North Fork of the Eagle River, a semi-clear-water tributary that occupies a previous channel of the Eagle River and is now fed by springs and small tributaries. Overflow from the main stem of the Eagle River sometimes occurs, feeding sediment-laden water into the North Fork. The adult salmon migrate from Knik Arm through the Eagle River to the North Fork to spawn, and the juvenile salmon migrate from the North Fork to Knik Arm. There was general consensus among the fisheries agencies that maintenance of natural runs was pref- erable to attempted mitigation by means of hatcheries or planted fish. Fish ladders are preferred over trap-and-haul facilities for moving adult salmon upstream. Juvenile salmon migrate out of the river primarily from mid-May to the end of June. The reservoir would be almost empty during that period and the outlet gates would be open, so juvenile salmon would be able to pass freely downstream. Some young salmon may be lost unless screening is provided at the water supply diversion intake. Flow Requirements The MAUS suggested an approximate minimum flow of 31 cfs (20 mgd) for Eagle River below the diversion point (U.S. Army Corps of Engineers, 1979). This value represents the minimum averagE! flow recorded during the relatively short period of re- cord. The extent to which the lower Eagle River is used by salmon and trout is not presently known. If extensive use is found to occur, minimum flows in excess of 20 mgd may be req u i red. Studies are needed to determine the importance of the lower Eagle River for fisheries. Sediment Sediment would be deposited in the reservoir; however, because the reservoir would be emptied in the summer, the flushing action of the Eagle River should help mitigate this impact. The pro- posed project will probably result in a net decrease in sediment discharged by Eagle River downstream of the dam. The project may also alter the seasonal pattern of sediment dis- charge. Not all of the sediment in the turbid water stored in the summer is expected to settle in the reservoir. Winter releases from the reservoir are thus expected to contain more suspended fine SE!diments than the natural winter river flows. The winter releases may also be warmer than the natural winter flows. If extensive spawning occurs in the lower river below the dam, it could be affected by increased discharge of sediment during the winter and the potentially higher water temperature. 7-3 Mitigation of Fisheries Losses If the project results in fisheries losses, mitigation would prob- ably be required. Measures discussed included spawning chan- nels or a hatchery downstream from the reservoir, increased production at existing hatcheries, enhancement and management of known spawning areas in the North Fork of the Eagle River, and enhancement in other watersheds. The agencies, in general, indicated that protection and enhancement of natural populations are best. Fk1utna, Inc., suggested that mitigation through hatcheries would be acceptable. Changes in Microclimate The water stored in the reservoir would probably cause some localized changes in climate. While the reservoir is operated for winter storage only, winter air temperatures in the immediate vicinity should be somewhat higher. If the reservoir were con- verted to year-round storage, summer temperatures in the vicinity of the reservoir would be slightly lower. Any small changes in microclimate would probably be restricted to the immediate vicinity of the reservoir. Wildlife Primarily, the agencies expressed concern over loss of habitat by wildlife. Specific items of concern are included in the following discussion. Loss of Habitat for Game Animals A variety of small game animals and moose are known to use the Eagle River Valley, including the reservoir site. Clearing the reservoir site of vegetation and seasonal filling of the reservoir would result in a net loss of wildlife habitat. Some plants, such as willows and grasses, tolerate periodic inundation. T hese plants might persist and thrive in the upstream part of the res- ervoir and around the margins in shallow areas. Loss of Habitat for Nongame Species Raptors, including bald and golden eagles, use the Eagle River a rea. Nesting sites have not been observed in the project area. It is not clear whether the project will have a negative effect on raptors, but the possibility exists. A variety of small birds also nest in the project area. There would be a net loss of habitat for these species and for small mammals living in the area of the reservoir. Shorebirds that feed on mudflats might gain some habitat from the project. 7-4 Groundwater Depending on local soils, the proposed reservoir could affect groundwater resources in the immediate area. A specific concern was expressed that the presence of the reservoir would raise the level of shallow aquifers in the area around the shoreline and downstream from the damsite. It is not known whether such effects might be positive or negative. Private and public wells in the area are dependent on local aquifers. Water Quality Concerns were expressed over the effects on the quality of Eagle River water, particularly in the reservoir, caused by discharges from man-made sources in the watershed. Another concern was the effect on water quality, downstream from the project, because of the loss of dilution water for discharges from the Eagle River Sewage Treatment Plant. There were several items of spe- cific concern. Leachate from Old Dump A former dump is located on the south side of the Eagle River about 1 mile west of the damsite (Figure 1-3). The ground sur- face in this area drains to the east through a natural wetland and discharges to the Eagle River immediately upstream from the pro- posed damsite. Unregulated dumping occurred for a number of years; therefore, there is a possib ,ility that toxic leachate may find its way to the reservoir. A water quality sampling program would be required to determine if leachate is a problem. If toxic leachates are found, diversion and/or treatment facilities may be required, or the dump may have to be removed. Septic: Systems Much of the development in the Eagle River Valley is presently unsewered. It is not known at present whether faulty septic systems are contributing bacterial contamination to the Eagle River. Studies may be required to determine if sources of bac- terial contamination exist. Possible effects of future residential development along the Eagle River were also of concern. The possible restriction of develop- ment is discussed further under Land Use. Recreational Use of the Watershed A third potential source of water quality problems may be from recreational use of the watershed. The Eagle River and the North Fork are currently popular areas with canoeists and kay- akers. Some recreational fishing also occurs in these areas. The Chugach State Park visitors' area at the end of Eagle River Road is another potential source of contamination. 7-5 Large expanses of frozen snow-covered mudflats may be exposed in some winters when inflow is low and releases high. These areas would be likely to attract snowmobile riders during the winter months, as would the reservoir surface if ice conditions permit. Use of snowmobiles in the area would pose a threat of contamination by petroleum products and bacteria. Land Use There is general concern, particularly among the planning agen- cies and the Division of Parks, over the issues of land use and planning in the Eagle River watershed. Specific issues range from the need for a comprehensive land use plan to concerns over dam safety. Need for Land Use Plan There is currently no land use plan that has been agreed on by the various groups having ownership in, or management responsi- bility for, the Eagle River drainage area. Several parties sug- gested the need for the Municipality of Anchorage to participate in such a plan. The project should conform with existing plans. Effects of the Proposed Project on Land Use Options The presence of a water supply reservoir could either restrict or enhance land use options in the watershed. For example, recrea- tional use of the area might be restricted, some residential devel- opment might be precluded or discouraged, some existing trails would be flooded, and potential access routes would be affected. Power Line Crossing It was noted that an existing power line might require relocation or higher poles. Dam Safety Concern was expressed over stability of the dam during seismic events and potential effects of dam failure on structures located downstream. The potential, effects of altered groundwater con- ditions on stability of soils in the alluvial benches downstream from the reservoir were also of concern. Records of existing pri- vate and institutional wells might provide clues on this issue. Aesthetic Effects There are no known major archeological sites in the proposed reservoir area. Specific concerns are with minor archeological sites, the Iditarod Trail, and the visual impacts of the project. 7-6 Historical and Archeological Sites Accordi@ng to Eklutna, Inc., there are probably no major ancient village sites in the project area. There are certainly remains of a number of temporary campsites whose locations are unknown. Portions of the historic Iditarod Trail pass through the Eagle River 'Valley and might be inundated by the proposed reservoir. The precise location of the trail in the area is not known, but it may have passed through the present Eagle Heights subdivision, which is near the proposed reservoir site. Visual Impacts The conversion of a vegetated river valley into a periodically flooded reservoir would create a visual impact that would be judged as an adverse effect by some residents of the area. The magnitude of this problem cannot be assessed currently because the group most likely to be concerned with visual impacts was not included in the conferences. SUMMARY There are a number of environmental concerns that must be addressed in the final design of the Eagle River dam. At pre- sent, adequate data are lacking to gauge the potential impacts discussed in this chapter. Studies must be made prior to or as part of the final design of Eagle River Dam to obtain the following data: 0 Fisheries. Insufficient data are available about the type, number, migration, and distribution of fish in the river. These data are essential to evaluate potential impacts of a dam and to provide satisfying mitigation of these impacts. 0 Sediment. Insufficient data are available at present to c M on id-ently predict the potential impacts of a dam and reservoir on sediment deposition and transportation patterns. 0 Water quality. No data are available on the effects of the old Eagle River dump on surface and groundwater quality. Soils data must be obtained to evaluate the need for diversion, treatment, or other measures, if any, that may be required to develop the Eagle River as a water source. 7-7 Because of the large size of the proposed project, the number of potential impacts, the current insufficient amount of data avail- able, and the potential magnitude of some of these impacts, it is expected that an environmental impact statement (EIS) would be requi'red. We anticipate that preparation of an EIS for this proj- ect may require 3 or more years. If the Eagle River dam is to be further considered, determination of the need for an EIS should be made as soon as possible. If a need is established, studies to develop the EIS should then be started. 7-8 NO Chapter 8 00 MAJOR PROJECT ELEMENTS An analysis was conducted to establish the feasibility of construc- ting a dam on the Eagle River and to develop the basic concepts and geometry for such a structure. The analysis of the concep- tual dE!Sign of the dam and reservoir is based on data established by the field and laboratory investigations described in previous chapters. This chapter describes the major elements of the project. The Eagle River dam would consist of an 80-foot-high compacted earthfill dam with a 100-foot-wide gated chute spillway on the right abutment. The spillway gates would be 30-foot-square radial gates. The spillway would discharge into a horizontal apron hydraulic jump stilling basin. The dam would have two low-level outlet conduits, each 10 feet square. Each conduit would be controlled by a roller gate located in a control tower near the upstream end of the conduits. The base of the control tower would be buried in the upstream shell of the dam and would extend above the reservoir surface. Access to the control tower would be provided by a bridge from the dam crest. Fish facilities would be located near the stilling basin and on the upstream face of the dam. The location of the intake structure for the trans- mission pipeline has been assumed to be in the reservoir and sep- arate -from the dam, as shown in the MAUS report (U.S. Army Corps of Engineers, 1979). A plan of the reservoir is presented on Figure 1-2. A site plan showing the dam and major project elements is shown on Figure 8-1. FOUNDATION AND ABUTMENTS The dam would be founded on a combination of dense glacial fill and outwash gravels (left abutment), stiff lacustrine deposits (central portion), and alluvial channel gravels (spillway and right abutment). The site would be prepared by digging a foundation excavation in the area to be occupied by embankments or struc- tures. All overlying organic material, topsoil, recent or loose alluvial sediments, and unconsolidated colluvial material would be remOVE@d from this area. All materials that might be compressible, subject to liquefaction during seismic loading, subject to erosion piping, or produce a zone of weakness or high permeability would also be removed. This removal would provide the best possible bond between the dam and its foundation. A core trench, as shown on Figure 8-2, should be excavated for the entire length of the dam. The excavation should be to a depth sufficient to ensure that loose or disturbed material beneath the core is removed or treated to prevent liquefaction or seepage concertrations beneath the core. It is anticipated that the core trench would typically extend about 5 feet into firm, undisturbed 8-1 glacial or alluvial deposits. The total depth below existing ground may be 20 feet or more in some areas. The actual depth should be field-determined by an engineering geologist or geo- technical engineer during dam construction. Organic material removed from the foundation excavation should not be placed in the dam embankment. Inorganic material re- moved from the foundation and core trench excavations can prob- ably be placed in the core or the shells of the dam, depending on its gradation and moisture content. The suitability of material for placement in the dam must be field-determined at the time of ex- cavation. Undesirable materials should be wasted. Dewatering Dewatering would be necessary during construction to control river underflow and to prevent other groundwater from entering the excavations. The quantity of water would vary with location and weather. It appears unlikely that pumping from the excava- tions, by itself, would be adequate to control groundwater. Studies should be made during design to determine the advisa- bility of wellpoint, slurry trench, deep-well, or other dewatering systems. An artesian flow of 1 to 2 gallons per minute was observed during drilling at boring B-6 (see Figure 5-1). According to this boring, the source of this water is a gravel layer found just above the rock at the bottom of the boring. The top of this gravel layer was observed in boring B-6 at an approximate elevation of 230 feet. The lowest point in the core trench excavation is pres- ently estimated to be at about elevation 255 feet. It may be necessary to clewater this gravel layer using deep wells and pumping to prevent heaving of the bottom of the core trench excavation. Surface water that flows into the foundation and core trench ex- cavations and groundwater not intercepted by the construction dewatering system should be collected in ditches, led to sumps, and pumped from the excavation. Control of water is of critical importance because of the moisture sensitivity of the lacustrine deposits beneath the damsite. Foundation Preparation Special preparation of the core trench excavation is often re- quired to ensure a firm bond between the core trench material and the dam foundation and to prevent seepage concentrations ad- jacent to the core trench fill. The exact type of preparation cannot be determined with certainty until the core trench exca- vation is open. It is anticipated that the only preparation neces- sary would be removal of all loose material and removal of any gravel stringers or other pervious zones passing beneath the core 8-2 42 0 2 7 0.5 421 0 2 6 60 D 7, x 2,4 ?71 0 S, filip in h ? spfll Gat, 4170 Bridge Access Bridge --- - --- --- .4 1@ 7"1' 0@ SEW _i*ro NORINIAL --UVEL.'ELi5V-336--- 0*011 r >; Fish ilitles 2735 z 4 5 284 V 0 ............ 1.q-11 N IAC@EgiRVOIR .... ...... -z-w- lit @'4 2 .................... 7 Elevations are in Feet It 01' DAM G"NULAR 6URM@IVCT &Lev. 3@ MAXIMUM 1?e5,-AV@R V -LEV t &CleL C 344 Ak@ R&55T@IT LE@L @CL1335 go, I 1 3eO 0 @T O@ k: /pT 0@ ELeU Ell 300 BeD@1@4 W&4-L C, -RC- - UrSbf&@ /0 MA ll@--,Olq 7/0,U O@Iaw@ COOMO CLEV 4ARIZ55 7,T H @AWAGC WELL.5 10 rl. AOe,V-1ZC-0 5,'C7/0,V AT 19441 HC-15HT CO ,-A e e 1@ 'E47 Figure 8-2' Dam Section of the dam. The base of the core trench should then be proof- rolled to ensure that all loose material has been removed. Care would have to be exercised to protect the foundation material where the foundation is excavated to lacustrine deposits. These deposits are moisture-sensitive, and can be difficult to keep in a dense state if moisture and drainage are not carefully controlled. Other special provisions may be required depending on the con- ditions disclosed during core trench excavation. DAM SECTION The proposed dam section is shown on Figure 8-2 and the profile is shown on Figure 8-3. The dam would be a zoned earthfill dam with a thick central core, an upstream blanket, a chimney drain, and a downstream drainage blanket. The upstream and down- stream shells would be constructed of well-graded sands and gravels excavated from the reservoir area and spillway. The chimney drain and downstream drainage blanket would be con- structed of selected processed material from the shell borrow area or from river bars in the reservoir. The core would be con- structed of low permeability sandy silt excavated from the reser- voir area. During final design, more detailed borrow area explor- ations should be conducted to verify that sufficient material is available to construct the dam and to attempt to locate silty material for the dam core that has a significant fraction of sand and gravel. This would reduce its susceptibility to internal ero- sion (piping). The dam shells, the chimney drain, and the downstream drainage blanket would be well compacted to minimize the possibility of liq- uefaction during seismic shaking. The core and the upstream blanket also would be compacted to a high degree of density. In addition, they should be compacted at a moisture content near or wetter than optimum moisture content. This would reduce the core material's permeability and increase its flexibility. Riprap should be placed on the upstream face of the dam to pro- tect the dam from wave damage. The riprap would be well- graded, imported stone with a maximum size of 18 inches, a median size of 12 inches, and a minimum size of 6 inches. This material would have to be imported because a suitable source of riprap is not available at or near the damsite. Bedding should be provided to act as a transition between the riprap and the upstream shell material. The bedding would pre- vent embankment material from washing out through the riprap because of wave action. Riprap bedding would be a well-graded material with a 6-inch maximum size. It is probable that suitable material can be selectively excavated or processed from the bor- row pit for shell material. If not, imported material would have to be used. 8-6 DAO CRI-Sr 3513 Z40 NORMAL -5ff@VOIR L-@Va@ ELEV 3- X30 @@R@ TE EX16TIIG @13 310 5rPILLWAY <711@@-6T -Cx1r1E5 3 @7 0/,4 REL CA 5 E L /AIE 060 EAGLE RIVC-R CH,qAIAI -070 /0.0c) //-00 /R@ 00 13,00 14-00 15ioo /@,+00 /7,00 IS.00 1q,00 6TATIOAIIAIG ALOA16, DAM CC-@7-EWLIAIC ,r,E5 Figure 8-3 Dam Profile The downstream face of the dam would be covered with topsoil and planted to minimize erosion of embankment material. The topsoil would be selected from material stripped for foundation excavation. Gravel surfacing would be used on the dam crest to prevent sur- face erosion and to allow its use as an access roadway. Gravel surfacing would be a well-graded crushed stone with a maximum size of 314 inch. Seepage Water would leak from the reservoir and dam. Seepage can occur through the dam core, under the dam core, through the dam abutments, and through the reservoir sides and bottom. There are two principal adverse effects of seepage: water loss and re- duced dam stability. Because minimum streamflow must be main- tained on the Eagle River, some water loss is acceptable as long as it does not reduce the dam's stability. The presence of the lacustrine silt deposit at a depth of 10 to 20 feet below the riverbed is expected to minimize the amount of seepage passing beneath the dam. Most of the seepage is expec- ted to pass through the sand and gravel layers located above the silt in the dam abutments. Based on the results of the laboratory gradation tests, we expect the permeability of the abutment materials,to vary, with an average permeability on the order of 10 feet per minute. The estimated seepage loss.through the dam foundation and abut- ments is not expected to exceed 2 cfs (1 .3 mgd). It is antici- pated that most of this water would discharge into the Eagle River immediately downstream of the dam. This seepage would contri- bute to the minimum flow of the river. One of the potential adverse effects of seepage at the site is ero- sion of the steep slope immediately downstream of the dam on the southwest valley wall. This could result from leakage through the left abutment. The surface material in this area consists of unvegetated silty sand and gravel. Frost action will assist in the erosion process. To minimize the seepage that may emerge in this area, the natural soil cover on the upstream slope of the left abutment should not be disturbed during construction. This would help provide a natural low permeability blanket to reduce the quantity of seepage entering the left abutment. Additionally, silt from the reservoir water would be drawn into any areas of infiltration on the left abutment during the first few years of reservoir operation. This silt would help form a natural blanket over seepage infiltration points on the left abutment and over the entire reservoir area. 8-8 If seepage emerging on the valley. wall continues to cause erosion after several years of dam operation, horizontal drains could be installed in this area. Because of the potential difficulties asso- ciated with keeping these drains clear of ice, they should be considered only if the other methods mentioned above fail to con- trol the erosion satisfactorily. A blanket of core material beneath the upstream dam shell would be provided. This would increase the length of the flow path for seepage passing beneath the dam, and thus reduce its quantity. It also will reduce the magnitude of the seepage forces beneath the central portion of the dam and would increase the dam's stability. To further reduce seepage pressures beneath the dam, drain wells will be provided downstream of dam core. These are shown on Figure 8-2. These drain wells would collect the seepage and dis- charge it at controlled locations rather than permit it to exit un- controlled where the dam meets the abutments. Seepage through the reservoir sides and bottom can only be roughly estimated. The Eagle River Valley contains a very heter- ogeneous assemblage of glacial and alluvial deposits overlaying relatively impervious bedrock. Seepage that flows into the sedi- mentary materials in the valley would, for the most part, not be lost to the underlying bedrock. However, the seepage path can- not be evaluated, except on a local scale, near the damsite. The presence of widespread glacial lake deposits beneath the damsite and in the reservoir area would help reduce the seepage losses. While iit is extremely difficult to estimate the amount of potential seepage, we anticipate that it would probably not exceed 4 cfs (2.6 mgd). This estimate is based on the general geology of the valley, the results of Task 1 to date, and the,gradation charac- teristics of the materials sampled during the damsite exploration. Cracks may develop in dams from differential movements or from irregularities in the foundation materials. Seepage in open cracks can cause enlargement because of flow concentration along the cracks. This process, referred to as "piping," can lead to dam failure. In order to provide adequate protection against failure of the dam by piping, a chimney drain immediately downstream of the core has been provided in the design. This drain would prevent migratilon of fine material from the core. It would also provide drainage for the downstream shell of the dam. Seepage inter- cepted by the chimney drain would be conveyed to the down- stream toe of the dam through the downstream blanket and would be discharged into the Eagle River from the blanket. A graded filter is provided at the downstream end of the blanket to prevent loss of fines into the river. Freezing of the discharged seepage is not anticipated to be a problem. The seepage water tempera- 8-9 ture would be above freezing, and would discharge continuously below river level at the toe of the dam. Settlement Some settlement of the dam is expected. Short-term settlement would result from elastic compression of the foundation and embankment materials during the construction of the dam. Long-term settlement would result from consolidation of compress- ible lacustrine silt deposit in the dam foundation. The geologic evidence and the results of the laboratory consolidation tests indi- cate that the amount of settlement would be tolerable because the silt deposit has been subjected to a high preconsolidation pressure in the past. The amount of potential settlement is dependent on the slope of the reloading curve for the stiff silt; the large size of the dam and the resulting great depth of its influence on in- situ stresses; and the thickness of the compressible soil. The methods presently available to estimate the amount of consolidation of highly preconsoliclated soils are expected to yield only an approximation of the ultimate settlement. The settlement caused by consolidation of the compressible layers in the dam's founda- tion is expected to be on the order of 6 inches. To compensate for this settlement, the dam crest would be constructed to an ele- vation above the nominal crest elevation by an amount varying from 1/2 foot at the dam ends to I foot at the point of maximum- height. The time over which the settlement would. occur is dependent on the permeability of the soil and the location of more pervious drainage layers. Only an approximate time can be estimated, because of the complexity of the drainage conditions beneath the dam. We anticipate that 90 percent of the settlement will occur within approximately 1 year after the completion of construction. Stability Analysis The stability of the dam was evaluated with respect to resistance of the embankment to shear failure under different loading condi- tions. A generalized section of the embankment at its maximum height is shown on Figure 8-2. This generalized section was analyzed for stability under the following conditions: 0 Downstream slope, normal operating conditions 0 Upstream slope, normal operating conditions 0 Upstream slope, sudden complete drawdown conditions Stability of the dam during earthquake shaking is discussed later under Seismic Considerations. A separate analysis was not made for the end-of-construction conditions because these conditions B-10 were assumed to be similar to the sudden complete drawdown conditions. The embankment consists of a number of zones. To analyze the stabilit,'K of the embankment, the shear strength parameters were identified for the materials in each of these zones. For the dam shells and foundation materials, the shear strength parameters are based on results of laboratory tests performed on samples of material from the field exploration program. For the dam core, chimney drain, and drainage blanket materials, conservative parameters are assumed. Table 8-1 presents the shear strength parameters and the unit weights used in the analysis. Table 8-1 MATERIAL PROPERTIES Shear Stren2th Parameters Moist Effective Effective Unit Friction Angle Cohesion Weight Material Type (degrees) (psf) (pcf) Dam Core and Upstream Blanket 30 0 100 Dam Shells 40 0 140 Chimney and Blanket Drain 40 0 140 Lacustrine Deposits in Foundation 35 0 124 Gravelly Sand in Foundation 44 0 1140 Gravel in Foundation 40 0 140 Initially, the stability of the dam under normal operating condi- tions 'was analyzed using the infinite slope method for both the upstream and downstream slopes (Taylor, 1948). The results of this analysis indicate that both the upstream and downstream slopes would be stable at a slope of 1.8 (horizontal) to 1 (verti- cal) with a factor of safety of 1.5. However, as discussed later in this chapter, under Seismic Considerations, it is recommended that the slopes be constructed at a slope not greater than 3 to 1 to reduce the potential for crest settlement from earthquake loading. 8-11 After acceptable slopes for the dam shells were determined, it was necessary to analyze potential deep shear surfaces passing through the damls core and foundation. To do this, more de- tailed stability analyses were made with STABL, a computer pro- gram for analyzing general two-dimensional slope stability prob- lems by a limiting equilibrium method (Siegel, 1975). STABL uses the Modified Janbu method of slices. This method allows for analysis of irregularly shaped shear surfaces as well as circular surfaces. Values of the factor of safety computed by this method are slightly conservative when compared with other equilibrium methods of slices. The computed factors of safety for the cases analyzed, critical shear surfaces, and the assumed piezometric surfaces are shown on Figure 8-4. In addition, the following assumptions were made: 0 Full drainage is expected in t-he embankment. Full drainage assumes that internal drainage would remove all seepage through the core and the foundation without pore pressure buildup in the downstream shell. 0 The drawdown analysis assumed no drainage whatsoever in the core of the dam and complete drainage in the up- stream shell. Drawdown was assumed to occur instan- taneously from the normal reservoir elevation of 338 feet to the lowest outlet elevation in the reservoir, elevation 275 feet. The riprap and riprap bedding on the up- stream face were assumed to drain instantaneously. Freeboard Freeboard must be provided to compensate for waves, wave runup on the face of the dam, wind setup on the reservoir surface, pos- sible dam settlement due to earthquakes, reservoir surface per- turbations during earthquakes, and a minimal residual freeboard amount. For the Eagle River reservoir, we estimate that the maximum wave height will be approximately 4 feet. This wave height is based on an effective fetch of 2 miles and a wind speed of 70 mph blow- ing along the reservoir toward the dam. Under these conditions, 4-foot waves would develop after approximately 20 minutes of sus- tained wind. When the waves strike the embankment they would run up on the sloping riprap surface. The estimated height of the runup is approximately 1/2 the wave height, or 2 feet for Ahe maximum expected wave. One foot of freeboard has been provided to compensate for settle- ment of the embankment crest during seismic shaking. 8-12 RESULTS OF STABILITY ANALYSIS COMPUTED FACTOR MINIIIAUM ACCEPTABLE CASE CONDITION OF SAFETY FACTOR OF SAFETY I DOWNSTREAM NORMAL 2.4 1.5 OPERATING CONDITIONS 2 UPSTREAM NORMAL 2.2 1.5 OPERATING CONDITIONS 3 UPSTREAMINSTANTANEOUS 2.0 1.0 COMPLETE DRAWDOWN 010 DA OUTLINE CASE2 CASE3 @CASE C @AS E 3@@@ Figure 8-4 Stability Analysis Five feet of residual freeboard have been provided to compensate for other ea rthq ua ke- related unknowns such as potentially greater crest settlement during unexpectedly large post-construction em- bankment or foundation settlements, unusally large waves, or seiches or other reservoir surface perturbations. This provides a total of 12 feet of freeboard above the normal reservoir level. During the PMF (refer to Chapter 3), 5.5 feet of freeboard would remain above the maximum reservoir level. Seismic Considerations A preliminary estimate of the expected peak and effective bedrock accelerations during the maximum credible earthquake (MCE) was made by Lindval, Richter & Associates. Their report is included as Exhibit C. They estimate that peak bedrock accelerations of 0.40g may occur during the MCE. They also have estimated that the expected maximum effective bedrock acceleration would be approximately 0.33g. Accelerations of this magnitude could cause embankment failure if accelerations were amplified by soil over- laying bedrock or by soil in the embankment. However, as dis- cussed previously, the foundation soil is extremely dense, and the embankment soil would be compacted to a high degree of den- sity during construction. Therefore, these materials should not amplify bedrock motions significantly. The peak acceleration is repeated only a few times during the MCE. Newmark (1965) provides a method to estimate slope move- ments resulting from earthquake shaking. Using a horizontal peak acceleration of 0.5g, Newmark's method predicts a down-slope movement of 0.3 foot. This slope movement takes place along a 3 to 1 slope, and would thus correspond to approximately 0.1 foot of vertical displacement. The expected deformation from peak acceleration is small and would probably only cause minor localized movement of the embankment. Several features in the conceptual design of the dam section pro- vide additional measures of safety against dam failure during an earthquake. The materials proposed for construction of the shells and drainage zones are expected to have negligible unconfined compressive strength. This would prevent these materials from sustaining an open crack without collapsing. Therefore, after any displacement caused by earthquake shaking, even if a large open crack existed in the core of the dam, there could not be an open crack through the shells or drainage zones. The chimney drain immediately downstream of the core would be cohesionless and would thus be capable of healing itself of any cracks that may be caused by an earthquake or from settlement. This would keep the drain continuous and provide a filter to hold the core material in place, preventing dam failure by erosional enlargement of an open crack. The cohesionless nature of the upstream shell would provide material that can wash into any crack that may open in the dam core. 8-14 Because of its well-graded nature, the proposed shell material is expected to have relatively low permeability. Therefore, the amount of water that could leak through a crack in the core would be limited by the permeability of the upstream shell. The gravel in the shell and drain materials, and the fact that these materials are well graded, makes them inherently stable against internal erosion (piping). The worst condition that would exist after a major earthquake would be a zone of loosened material in the darn shells and the filter zones. Although the embankments might be severely damaged by the MCE, catastrophic failure should not occur. SPILLWAY The spillway would be located on the right side of the dam, with dam embankment on both sides of the spillway (Figure 8-1). It would consist of an excavated approach channel, a concrete ogee crest topped by radial gates, and a 100-foot-wide concrete chute leading to the stilling basin at the downstream toe of the dam. The spillway has been designed to pass the PMF with approxi- mately 6.5 feet of surcharge above normal reservoir level. A profile of the spillway is shown on Figure 8-5. The approach channel to the spillway crest would be unlined, 250 feet long, tapering from 200 feet wide at the entrance to 100 feE@t wide at the upstream face of the spillway crest. The approach channel would be at elevation 292 feet at the upstream face of the spillway. It would be excavated on an adverse slope of 0.0111 foot per foot to allow for drainage when the reservoir is lowered in the summer. This excavation would improve hydraulic operating characteristics of the spillway. In addition, the exca- vated material could easily be used in the dam embankment. Concrete retaining walls (wing walls) would be provided where the channel penetrates the dam embankment. The spillway crest would be placed at elevation 308 feet. The crest would be ogee-shaped with a 30-foot design head and a vertical upstream face. The crest would be divided into three 30-foot-wide bays, each containing a radial gate with a 30-foot damming height. Two piers and the side walls of the spillway chute would be used to support the gates, which would be oper- ated remotely from the proposed Eagle River water treatment plant. Hoist mechanisms are located on the deck, 42 feet above spillway crest. The radial gates would be provided with flexible seals at the sides and bottom of the gate skin plate. These seals would con- tact side rubbing plates and a sill plate embedded in the spillway structure. These seal plates should be heated in the winter to ensure that the gates can be opened in the event of an early spring flood occurring after a rapid rise in temperature. Heating 8-15 4 K @A@, LEVEL ftFt/ 338 OF -OPYLLWAY W4LL CL 181 1W ..... ARPROXIMATe AIVER LE@L (AT W TCV-VaRAF@41C Af@AJG. Oqu@ 6L.CK6 7'WIPC A@,TOXIMAT,5 __Z RIV15K Aeo 7,0' 14@WIZO@ITAL A@ACW eL, M47 511@ 5LOCA'5 co CI3 WIP& kK sa4LE IAJ I r '9 zo Figure 8-5 Spillway Profile of the seals would also prevent tearing or other damage to the seals that could occur if ice were allowed to form around them or on the seal plates. The seal plates would be heated by circulating warmed oil or antifreeze solutiQn thrQugh pipes embedded behind the seal plates. The seal plates need only to be kept warm enough to prevent ice formation. A 60-loot-radius reverse curve would be used as a transition be- tween the ogee crest and the 100-foot-wide chute. The curve would become tangent to the chute at approximately elevation 289 feet and continue on a constant slope of 0.227 foot per foot for 185 feet to the stilling basin. Some cost savings may be real- ized by tapering the spillway chute; this detail can be considered in the final design. The spillway is sized to pass 57,000 cfs with the reservoir at nor- mal rE!servoir level, elevation 338 feet. This provides capacity to hanclk@ a flood equal to one-half of the PMF without surcharging the reservoir. The spillway rating curve is provided in Figure 3-30. The above conceptual design differs considerably from that con- ceived in the MAUS (U.S. Army Corps of Engineers, 1979). The Corps' design assumed a reservoir with a maximum surface elevat@ion of 325 feet. The spillway was to have two radial gates, each 50 feet wide by 50 feet high. The floor of the spillway was to be level with the natural riverbed (approximately at elevation 268 feet) to allow nearly unrestricted passage of summer flows. This concept was not used for the present study because our reservoir operations study indicated that the normal reservoir level needs to be at elevation 338 to meet the required water demand. The 70-foot-high gates required to store water to this elevation were considered to be uneconomical. Several other spillway configurations were considered for the dam: uncontrolled spillways, wider spillways, and spillways with no surcharge storage. The PMF was routed through the reser- voir using uncontrolled, ungated spillways of varying widths. Surcharge above the normal reservoir level varied from 29 feet for a 100-foot-wide ogee spillway to 19 feet for a 250-foot-wide ogee spillway. However, a gated spillway is necessary to mini- mize the flooding of the Eklutna, Inc., land upstream of the pro- posed reservoir site. Also, space limitations at the site indicated that construction of a spillway much wider than 100 feet would become very difficult and expensive. Routing studies indicated that a 160-foot-wide spillway with 30-foot-high gates would be required to pass the PMF without surcharging the reservoir above normal reservoir elevation 338 feet. The expense of this struc- ture was considered excessive for the benefit of no surcharge storage. B-17 The proposed 100-foot-wide gated spillway provides no surcharge storage up to one-half the PMF, while allowing a reasonable 6.5-foot surcharge during the PMF. STILLING BASIN The stilling basin is located at the toe of the dam. Space limita- tions at the site make it necessary to combine the energy dissipa- tion structures for the spillway and outlet conduits into a single stilling basin. This is best accomplished at this site with a hori- zontal apron hydraulic jump basin. A standard Basin 11, as shown in the U.S. Bureau of Reclamation's (USBR) Design of Small Dams (1974) was chosen for use. The basin is 100 feet wide-, -16-0-7eet long, and has a floor elevation of 247 feet. It was chosen because the incoming flow velocities can exceed 60 feet per second. This design does not incorporate baffle piers on the basin floor because of the potential for damage by the high veloc- ity flow. However, the basin does have a row of chute blocks at the intersection of the chute and the basin floor and a den- tated end sill to help shorten the hydraulic jump length. The exit channel is excavated on a slope of 20 percent until it meets the streambed level. The outlet conduits empty into the spillway stilling basin by pene- trating the left stilling basin wall. The outlet conduits would normally be discharging only when the spillway is not operating. Under this condition, the water level in the stilling basin would be very near the invert of the conduits, and the stilling basin would function as a plunge pool. Space limitations at the site and hig.h construction costs led to the stilling basin being designed for a spillway flow of one-half the PMF. The one-half PMF is an extremely infrequent event, with a very low probability of occurrence during the life of the project. However, because the spillway design calls for passing the full routed PMF, there is some probability that the capacity of the stilling basin would be exceeded. Under these conditions the stilling basin may be damaged, but the integrity of the dam is expected to remain. The possibility of having to perform some repairs on the stilling basin is considered to be an acceptable risk in view of the extremely low probability of such an event occurring. OUTLET WORKS Outlet conduits would be provided to divert the river during construction, to control downstream flows, to assist in control of the reservoir surface level, and to provide a conduit for possible future hydroelectric facilities. They would be located near the spillway and discharged into the stilling basin. 8-18 Several , configurations, sizes, and number of outlet works were considered before the proposed design was chosen. One consid- eration was to have the outlet conduits within the spillway struc- ture rather than in the spillway stilling basin. This would have allowed a permanent pool 35 to 40 feet deep, with the following advantages: 0 Less pumping would be required to transmit water in the pipeline 0 Minimum streamflow discharges would have enough head to be used for hydroelectric generation 0 All low-level dam penetrations and the associated control tower would be eliminated 0 All spillway and outlet controls would be close together 0 A fish ladder could be more easily provided There would be the following disadvantages to this alternative: 0 Additional dead storage would be created because the area below the outlet works would not be usable and would fill up with sediments 0 Construction of the dam would be more complicated because the contractor would have to build the spillway first, then build temporary structures in the river to divert the river over the spillway while the dam is built 0 The spillway section would be much more complicated with penetrations for the outlets, gate chambers, passageways, and control rooms It should be noted that the first disadvantage is not major because this dead storage can be recovered with only a minimally higher dam and reservoir. The advantage of increasing the head could be achieved by throttling the low-level outlets with the roller gates. The proposed design of the outlet works would consist of two 10-foot-square reinforced concrete conduits and a 3-foot-diameter pipe. Flow in the square conduits would be controlled by roller gates. The conduits would have an entrance invert elevation of 275 feet, 3 feet above the existing river bank. They would have a slope of 1 percent and have an exit invert at 270.5 feet at the stilling basin wall. Figure 3-31 shows the rating curve for one conduit. When both conduits are flowing, the combined flow would be approximately twice the value shown on the rating curve. 8-19 The outlets would have trashracks and stoplog slots I'at the entrance. Downstream of the entrance a wet well is provided for the roller gates. Another set of stoplog slots is provided at the downstream end of the conduits. Stoplogs can be used to de- water the conduits for inspections, repairs, and modifications. The conduits enter the stilling basin through the side wall at about a 15-clegree horizontal anglLa from the spillway axis. Therefore, one of the square conduits would be longer than the other. The average conduit length is 450 feet. The 3-foot-diameter pipe provides the minimum downstream flow requirements when the roller gates are closed. A valve is p .ro- vided for accurate control of the flow volume in the pipe. Figure 3-32 shows the rating curve for this pipe and for two larger pipes. A larger diameter pipe may be required if: (1) final design fish flow requirements are higher than the 31 cfs used in this analysis, or (2) the 108-cfs municipal demand is transmitted through the dam to a downstream pump station. The MAUS report (U.S. Army Corps of Engineers, 1979) suggested withdrawing water from the reservoir through a pump station located in the reservoir. During final design, consideration should be given to alternative withdrawal points, including imme- diately downstream of the dam or along the river near or down- stream of the Glenn Highway bridges. The square conduits would be designed to allow the river to flow very close to natural conditions in late spring and summer. Dur- ing this time period, the water surface at the upstream side of the dam would not be higher than elevation 290, except for very short periods. This design would promote the movement of sedi- ments through the empty reservoir during the period when most of the sediment is being transported. The final design of the outlet works and pump station intake would determine the number, size, and location of all dam penetrations. RESERVOIR The normal pool surface would be at elevation 338 feet, with a reservoir surface area of 2,530 acres and a total storage volume of approximately 55,000 acre-feet. The maximum pool surface would be at about elevation 344.5 feet, with a reservoir area of approximately 2,840 acres, and a total storage volume of approxi- mately 71,200 acre-feet. A plan view of the reservoir area is presented on Figure 1-3. Land Considerations At present, the site for the proposed reservoir is covered by scattered spruce, birch, and other trees. Unless the fisheries agencies request that the dead trees be left to provide habitat for 8-20 fish, they should be cleared and removed from the reservoir prior to the first filling. Clearing should be accomplished during Feb- ruary through April when the trees are dry and leafless. Stumps and roots should be left in place during clearing to help hold the soil in 'place and to reduce surface erosion. During and after clearing, the portion of the reservoir site up- stream of the left abutment should be evaluated with additional subsurface exploration and geological mapping in more detail to verify the size and location of pervious sand or gravel deposits. If pgrvious layers are found to extend through the left abut 'ment, it may be necessary to construct an artifical blanket in this area to reduce seepage losses. It is preferable to leave the topsoil and the overlying organic mat in Place to minimize erosion. Usually, such materials can be left in place without significant impact on water treatability. The possible need to remove the organic mat should be evaluated during final design. There is a potential for reservoir contamination from leachate from the old Eagle River dump, located west of the damsite. A surface water and groundwater monitoring program will be necessary to evaluate the possible effects' of this dumpsite on the proposed Eagle River Reservoir. Landslides in the reservoir area could occur as a result of sudden drawdown or as a result of rapid saturation caused by water infil- tration into the ground surface once the surface vegetation is re- moved. The normal rate of drawdown should not exceed the withdrawal rate necessary to maintain minimum streamflows and to supply the water treatment plant. Based on the material types reported in previous geologic investigations and on our observa- tions of materials near the damsite, only minor erosional or sta- bility problems of the shoreline, such as shallow surface slides, are expected during normal reservoir operation. However, more cletailE@d studies should be made during design to determine accep- table maximum drawdown rates. Seismic Considerations Seismic tremors caused by the filling of the reservoir are not ex- pected because of the relatively shallow reservoir depth and the high degree of preconsolidation of the soils at the site. Several hundred feet of ice and glacial materials have been present over the rE.servoir area in the past. Thus, the addition of an average of 22 feet of water over the reservoir area is not likely to trigger an earthquake. While a few. instances of reservoir-induced seis- micity have been postulated, very little information is available on this subject. B-21 During severe earthquakes, incidents of vertical and/or lateral movements of massive earth or rock blocks have been recorded at various localities.. Very large areas have been raised, lowered, and/or tilted. Major vertical movements of portions of the reser- voir, or massive tilting of the entire reservoir area, could cause the dam to be overtopped. No method is available to predict the possibility of such-an occurrence. The only precaution is to pro- vide a reasonably large amount of freeboard. Waves in the reservoir may be caused by certain types of earth- quake motion that produce a slow rocking motion of the entire mass of water in the reservoir. These oscillations are termed seiches. Overtopping may result, although the only instance of record was also associated with massive ground tilting. No seiches caused by shaking alone have been recorded with heights of more than a few feet. Although at the present time no reliable method is available to predict the maximum wave height due to seismic activity, the minimum residual freeboard provides some protection against seiches. B-22 00 Chapter 9 00 CONSTRUCTION f AREAS OF UNCERTAINTY The construction of major earth structures involves more uncer- tainties than most kinds of construction work. Design considera- tions for major earth structures must be continually reevaluated throughout the construction period. During construction, the true character of the subsurface conditions is often found to differ from those indicated by the borings, test pits, and labora- tory tests despite thorough, careful investigations prior to con- struction. If conditions encountered during construction are different from those assumed during design, changes may be required. For this reason the design of a major earth embank- ment is a continuing process extending throughout the construc- tion period and into the early phases of operation. The impacts that can occur as a result of the inherent uncertain- ties related to subsurface conditions can be minimized if: 0 The owner recognizes that additional money over and above the initial contract bid amount may be spent during construction 0 The designer's representative is on-site to quickly identify "changed conditions," and the appropriate design changes are promptly made by the designer 0 Good communications are maintained between the owner, designer, and regulatory agencies so that all responsi- ble parties can approve design changes quickly The alternative to making design changes during construction is to design the dam so conservatively that it will be adequate under all of the "worst-case" assumptions. This requires a design that may be prohibitively expensive, and wastes money if the worst- case conditions do not actually exist. The following site conditions present difficulty for embankment construction and add to uncertainty at the Eagle River damsite: C@ The main dam requires a large volume of fill that must be taken from a sizable borrow pit. C1 The left abutment might contain pervious zones needing treatment to reduce seepage losses and improve abut- ment stability. C1 Deep cuts are required for the spillway approach chan- nel, for the stilling basin, and for embankment founda- tion preparation. 0 The seismic activity of the region would require flat slopes for the embankment. 0 A wide chimney drain and large downstream drainage blanket would be required because of the potential for ground shaking from earthquakes. 0 The material available for core construction is suscep- tible to cracking and would be sensitive to moisture content during construction. 0 For embankment safety during earthquakes, the dam must be carefully constructed under strict quality control for materials and compaction. 0 Filter and riprap bedding materials must be processed from selected onsite materials. 0 Riprap and granular roadway surfacing must be imported from offsite. 0 The construction season is relatively short, and maxi- mum river flows occur during the middle of the con- struction season. 0 The river diversion would require close attention by the contractor because of the narrow valley and the possi- bility of large flood flows during construction. 0 Dewatering would be necessary in the lower parts of the foundation excavation and core trench. Large flows may have to be handled if pervious zones are present. CONSTRUCTION SEQUENCE The construction sequence would be the contractor's responsi- bility. This sequence would depend on his experience, the type of equipment he has available for the project, the time required for delivery of items required for construction, and other factors. The sequence adopted should provide good construction conditions and minimize the possibility that the partially completed dam might be overtopped during construction. For project analysis, we have used the following generalized construction sequence: 1. Construct a cofferdam around the low-level -outlet and stilling basin construction areas, and divert the Eagle River to the extreme left side of the valley. 2. Construct the low-level outlet and the spillway stilling basin. 3. Construct cofferdams to protect the embankment and spillway work areas, and divert the river through the low-level outlet. 9-2 4. Prepare the foundation for the dam and the spillway. 5. Construct the main dam embankment, using material from-the spillway excavation to the maximum extent possible in the embankment. Construct the spillway at the same time. 6. Install major equipment and begin reservoir operation. CONSTRUCTION SCHEDULE We estimate that construction of the dam would take approximately 2 years under the following conditions: 0 No unusual conditions encountered that are not now apparent or that differ from assumptions made. 0 Work is properly organized by the contractor. 0 The contract is awarded early enough before the con- struction season begins to allow time for the contractor to organize the work and order items with long lead time (such as the radial gates). This will also allow the maximum number of days of good weather for con- struction, and allow the contractor to take advantage of seasonal streamflow variations in 'developing his work plan. 0 Access routes to all work areas are available to the contractor. 0 All necessary property not now owned by the Munici- pality of Anchorage is acquired, or easements are acquired, before construction begins. 0 All permits required are issued in a timely manner by the responsible agencies. Other than unusual circumstances such as acts of God, strikes, unusual weather conditions, or other unforeseen circumstances, the completion time is dependent on contractor operations. A competent, experienced contractor with adequate plans should be able to complete the project in 2 years without charging a premium price for a "rush" job. DIVERSION AND CARE OF WATER The handling of natural streamflow during construction of a dam is usually a key element of the work. The contractor would have control of the project site during construction, and would be required to provide for diversion of the river flow during construction. Because the diversion cannot be economically 9-3 constructed to handle all flows, there is a risk that the construc- tion site might be flooded, with resulting damages and delays. This is a risk for the contractor and, thus, for the owner. We anticipate that the contractor would divert water away from the construction area by first diverting it to the left side of the valley while the outlet conduits and stilling basin are being con- structed. Once these components are finished, they can be used in conjunction with an upstream cofferdam to pass streamflow until the dam is completed. The contractor might elect to use other methods to divert the river. We anticipate that the proposed core and shell materials would be sensitive to moisture content during compaction. This would require close moisture control to achieve satisfactory compaction. During construction the contractor may find that the natural moisture content of materials in the borrow area is too high or too low for satisfactory compaction. This would then require either removal or addition of water. During excavation of the core trench and for the foundations of the dam and the structures, springs may develop that may require drainage or pumping. COST ESTIMATE The estimated cost for the construction of Eagle River Dam is based on estimated quantities of materials and construction ser- vices required for execution of the conceptual design presented in this report. The cost estimate is presented in Table 9-1. These costs reflect April 1981 cost levels, and are based on our past experience and records. They would require escalation beyond April 1981 to account for inflation. The estimate given in Table 9-1 includes only costs for construction and engineering. It does not include items such as legal fees, easement acquisition, property acquisition, and financing costs. It also does not include the costs of fish facilities. These additional costs also will depend on the assumptions listed in the Construction Sched- ule section of this chapter. We believe that these are reasonable conceptual design cost esti- mates, but they do not constitute a quotation or guaranteed maximum because of the many uncertainties and unknowns that are beyond our control, such as the following: 0 The final design of the dam might differ from the conceptual design presented in this report. 0 Fish facility requirements have not been established. Consequently, the cost of such facilities has not been included. 9-4 Table 9-1 CONSTRUCTION COST ESTIMATE rn-,t-, hv r.;;tPrinrv fck) Fnrilitv Mobilization Sitework Concrete Equipment Electrical Totals Site Access 5,000 105,000 110,000 Dewatering 27,000 545,000 572,000 Dam Embankment 103,000 2,054,000 2,157,000 Reservoir Preparation 293,000 5,865,000 6,158,000 Spillway 387,000 448,000 5,696,000 1,603,000 250,000 8,384,000 Outlet Conduits 74,000 -- 1,484,000 -- -- 1,558,000 Control Tower 60,000 1,035,000 174,000 -- 1,269,000 Totals 949,000 9,017,000 8,215,000 1,777,000 250,000 20,208,000 Engineering at 15 percent 3,032,000 Tota 1 23,240,000 Notes: 1 All items include 25 percent contingency. 2. Costs do not include legal fees, easement acquisition, property. acquisition, financing costs, and fish facilities. 3. All costs in April 1981 dollars. 0 The effects of frazil ice on design, sedimentation, and water quality must be studied further. Changes in the final design might be required as a result of such studies. These changes might affect the cost of the project. 0 There are uncertainties in any cost estimate 0 Uncertainties in the competitive bidding process can have a strong effect on bid prices. Some factors that might affect the bid prices include the amount of other work available to contractors during the bidding period, the amount of backlog work contractors have at the time of the bidding, the number of contractors bidding on the project, the contractors' estimates of the difficulty of constructing the project, and the contractors' financ- ing requirements for the project in periods of inflation. As discussed previously, the construction of a dam involves a greater degree of uncertainty than most engineering projects. When changes during construction are necessary, they need to be reviewed, analyzed, and approved rapidly to allow construction to proceed. This type of change generally requires "change orders" to the construction contract. These change orders generally cause an increase in the project cost over the basic bid. The contingency amount provided in the cost estimate is intended to provide a reserve fund to meet at least part of the costs of changes, if required, and also as a contingency for other uncer- tainties inherent in the estimating and bidding processes, as described above. PERMITS A number of permits or similar authorizations from governmental agencies would be required for the construction of the Eagle River dam. The following is a list of agencies and permits that would or may be required: U.S. Army Corps of Engineers 0. Permit for Discharge of Dredged or Fill Material into Waters of the U.S. Alaska Department of Environmental Conservation � Water quality certification � Surface oiling permit � Solid waste disposal permit 9-6 Alaska Department of Fish and Game 0 Habitat permit 0 Anadromous fish protection permit 0 Determination of need for fishways resulting from obstruction of fish passage Alaska Department of Natural Resources � Water rights permit � Compliance with dam safety regulations � If state lands are affected: - Miscellaneous land use permit - Right-of-way or easement permit � If state park lands are affected: - State park noncompatible use permit - Disturbance of natural material permit Municipality of Anchorage 0 Miscellaneous permits that may include building permits and right-of-way permits In addition, the U.S. Environmental Protection Agency may re- quire an Environmental Assessment or an Environmental Impact Statement. The Cffice of the Governor, Division of Policy Development and Planning (Alaska Coastal Management Program), would make a "consistency determination. 11 This consists of a review of appli- cations for Federal licenses and permits, circulation of the appli- cations and information to the appropriate state agencies for review and comment, and a determination of consistency with state-level authority and regulations. The results of this consis- tency determination are submitted to the appropriate Federal agency. If AWSU decides to construct the Eagle River dam., the permit application process should be one of the first tasks in the final design process. 9-7 CONSTRUCTION REVIEW A full-time construction reviewer should be present at the damsite during construction to continually evaluate field conditions encoun- tered during construction and compare them with the design assumptions. This reviewer should be familiar with the design, with the geotechnical assumptions made during design, and with dam design and construction in general. The presence of a construction reviewer helps to identify differing conditions that are encountered during construction so that they may be properly addressed by the design engineers. He monitors the construction to evaluate its conformance to the plans, specifications, and any change orders that may be necessary. 9-8 on Chapter 10 ME OPERATION AND MAINTENANCE Ownership of a dam creates a continuing responsibility for the operation and maintenance of the dam. This chapter discusses some general considerations related to operation and maintenance of the proposed dam. The final design engineering tasks should include development of a detailed operation and maintenance plan. OPERATION Normal Operation The normal hydraulic operation plan for the dam is described in Chapter 3. It is anticipated that all of the reservoir control systems would be remotely operated from the proposed Eagle River water treatment plant. In addition, local override of the remote controls would be possible. A daily visit to the damsite by AVISU staff should be made to observe the condition of all facilities. Instrumentation should be provided to monitor reservoir levels, the groundwater elevation in the dam and the abutments, and the movement and settlement of the dam. Piezometers or observation wells would be used to measure the water pressure in various portions of the dam and the abutments, and survey monuments would be used to measure any movement or settlement of the fill. These measurements would provide data for permanent records that can be used to determine if the design assumptions are being met and to evaluate the long-term performance of the dam. These data would also provide background information for safety evalua- tions or repairs that might be needed at a future date. In addi- tion, the monitoring of reservoir levels would be used in the daily operation of the project. The conceptual design of the spillway allows for controlled open- ing of the spillway gates at rates less than or equal to a prede- termined rate so that downstream river levels would not rise rapidly. For this study, the rate of downstream river rise was limited to 2 feet per hour or less. This would allow sufficient time for persons downstream to leave the river area in the event of increasing discharges. Emergency Operation As mentioned previously, local override of all control systems would be possible at the damsite. In addition, backup operating power must be provided at the damsite by standby generators. 10-1 The three radial spillway gates can be fully opened, if needed, to an elevation above the surface of the water that is discharging through the spillway during an extreme flood. However, as mentioned above, the spillway gates would normally be opened at a rate that would limit the maximum rise in downstream river level to 2 feet or less per hour. The spillway would be designed to operate under all flood conditions up to the routed peak discharge of the PMF. However, it is expected that some damage might occur to the stilling basin as a result of discharges exceeding one-half the PMF peak discharge. This is because it is economi- cally impractical to provide a stilling basin that would suffer no damage during such an extremely unlikely event. It is antici- pated that repairs would be required to the stilling basin and possibly to the downstream toe of the dam embankment and fish facilities in the event that a flow of this magnitude occurs. It is important to operate the reservoir at all times to ensure that the normal reservoir level does not exceed elevation 338 feet. If the normal reservoir level is not held near or below this eleva- tion, there would be diminished storage available in the reservoir to store the excess inflow which would occur during the routing of the PMF. The reservoir level should be permitted to rise above normal only if all three radial gates are already fully opened and clear of the water surface, or to limit downstream water level increases to 2 feet per hour as discussed above. When the reservoir is full, there would be very small increases in water level above elevation 338 as needed for automatic reservoir sensors to detect a rising reservoir level. During floods that occur when the reservoir is full, the spillway gates would be opened to match outflow with reservoir inflow. EMERGENCY WARNING PLAN A flood warning plan would be required for residents downstream of the dam and for closure of the Glenn Highway and Alaska Rail- road bridges downstream of the dam. It would be used during severe flooding or in the unlikely event of potential dam failure. A dam break analysis and routing of the resultant flood wave would be required to determine the extent of potential flooding downstream of the dam. The emergency plan should clearly indicate the discharge and/or reservoir elevation at which steps would be taken to evacuate downstream residents and close these facilities. The plan should also identify other conditions that would require its use. Respon- sible government authorities or other agents who would agree to accept responsibility to carry out the flood warning plan must be identified. The emergency plan should be written, available in a number of places, and be conspicuously posted at the dam and at the water treatment plant control center. It should identify a series of backup personnel in the event the prime contact per- sonnel cannot be reached. 10-2 MAINTENANCE Both preventive and corrective maintenance would be required for the dam and control structures. Preventive maintenance would be necessary to keep the dam and control structures in satisfactory operating condition. Corrective maintenance may be required to repair the dam and control structures if they become damaged. A maintenance plan should be developed to provide routine guide- lines for the preventive maintenance of the structure. Some of the elements that would be part of a preventive maintenance plan are: 0 Periodic lubrication of gate hoists 0 Periodic inspection and replacement of hoist cables 0 Periodic maintenance of control systems, instrumen- tation, and actuators 0 Maintenance and repair of the roadways 0 Periodic mowing or brush control 0 Correction of minor deficiencies such as cracks or con- crete spalling as they develop and before they progress to the point of causing major damage 0 Periodic painting of exposed metalwork 0 Periodic collection of debris from log booms and trash- racks 0 Daily monitoring of ice conditions to allow early removal of unusual ice buildup that may hamper project operation Examples of the types of corrective maintenance that may be required include: 0 The abutments should be inspected regularly for the development of springs and presence of seepage water. If this occurs, means to control the seepage would be required. Control can often be accomplished by means of an upstream blanket of low permeability soil such as silt or clay over the area of infiltration in the reser- voir. In the event of excessive leakage, drainage trenches, blankets, pipes, or vertical or horizontal drainage wells might be required. 0 Corrosion of the gates, valves, and piping would grad- ually occur. These items should be inspected period- ically and repaired as needed. 10-3 0 Erosion of concrete in the stilling basin and around the radial and roller gates would occur because of the high velocity of the water. Structures subjected to high velocity water should be inspected periodically and repaired as needed. 0 During large floods, erosion is expected in the stream channel near the spillway stilling basin. It may be necessary to place additional fill in the vicinity of the stilling basin if it is undermined or otherwise threat- ened by such erosion. 0 Settlement of the dam may cause some visible cracks to develop on the surface. These cracks should be observed, measured, and repaired. This cracking and differential settlement is expected to occur within the first few years of reservoir operation. INSPECTION An ongoing inspection program is essential to the integrity of a major dam such as the proposed Eagle River dam. Such an inspection program should include both an informal and a formal program of inspection. The informal program is often the most important. The informal program requires that the normal operating personnel be con- scious of the day-to-day condition of the dam and of specific features that have been identified as potential hazards. In this manner, changes in site conditions can be noted and evaluated promptly. The formal inspection program should consist of a regularly scheduled systematic inspection of all features of the structure. This inspection should involve formal documentation, such as completion of a checklist developed specifically for Eagle River dam. In general, photographs of the dam should be taken from the same vantage points at each inspection. This type of inspec- tion provides a frame of reference against which to evaluate future changes in the dam's condition. The formal inspection should be performed at least annually. In addition, a formal inspection should be performed during or after every instance of unusually high water conditions. The establishment of a program of formal inspections with photo- graphs and records of the dam's condition assembled on a regular basis and kept indefinitely can aid significantly in future evalua- tion of the dam's safety. It is also advisable to have a formal inspection conducted at 5-year intervals by an outside agency or consultant having no 10-4 interest in the day-to-day operation of the dam. Such an inspec- tion provides an independent review of the dam's safety and condition. EFFECTS OF FUTURE CHANGES Under the criteria and assumptions given in this report, the dam and reservoir are designed for safe and efficient operation. Changes from these criteria or assumptions may produce undesir- able or- unsafe conditions in the dam and reservoir or downstream. Future developments in science and engineering might create a need to reevaluate the design criteria used. Changes in land use either upstream or downstream of the dam might change the design assumptions, and might create pressure to change reser- voir operation procedures. Any changes in reservoir operation method, reservoir operation elevations, or adjacent construction should be carefully evaluated by qualified professionals to deter- mine the possible effects of such changes on the dam and reservoir. Successful evaluation of the effects of changed conditions or future developments can only be adequately performed by quali- fied professionals experienced in the design and operation of earthfill dams. 10-5 ON Chapter 11 ON CONCLUSIONS AND RECOMMENDATIONS As a result of the Eagle River preliminary damsite investigation the following conclusions and recommendations are presented., CONCLUSIONS A dam can be constructed on the Eagle River that can be safely operated to provide municipal water supply and to safely with- stand the'maximum credible earthquake and the probable maximum f lood. The dam can be constructed to provide a water supply withdrawal rate of up to 108 cfs (70 mgd) if there are no major deviations from the following assumptions used in the investigation: 0 31 cfs is adequate for minimum downstream releases 0 Mitigation for fisheries can be achieved to the satisfac- tion of controlling agencies 0 Other environmental elements will not block construction of the dam or withdrawal of water from the river 0 Sediment deposition in the reservoir will not occur at a rate that will make the dam infeasible 0 All permits and licenses can be obtained from the appropriate agencies A dam that provides for a water supply withdrawal rate of 108 cfs is estimated to cost $23,240,000 in April 1981 dollars. This amount is for construction and engineering only, and does not include: 0 Land acquisition 0 Financing 0 Escalation to adjust for higher prices at the future construction date 0 Fish facilities RECOMMENDATIONS Many uncertainties encountered during the preliminary damsite investigation need to be resolved by additional studies before any dam on the Eagle River can be designed. If AWSU decides to pursue the Eagle River dam, we recommend the following studies or actions be completed prior to or during design: 0 Study the type, number, migration, and distribution of fish in the river to evaluate impacts of a dam and to provide satisfactory mitigation of the impacts. This study should lead to a decision on required minimum releases from the dam, by month if necessary, before design of the dam, because the size of the dam and reservoir is dependent on minimum release requirements. 0 Study the potential effect of the old Eagle River dump on reservoir water quality and evaluate any modifica- tions required to develop the Eagle River as a water source. 0 Study the variability of the water supply demand throughout the year, because a variable rate can affect dam size. 0 Install at least one precipitation station in the upper reaches of the basin to provide hourly precipitation values, and modify other stations in and around the basin to provide hourly precipitation values. 0 Recompute the PMF during design. 0 Study the winter regime of the Eagle River. 0 Perform a more detailed seismicity study for the site to determine the characteristics of the maximum credible earthquake and the dynamic response of the site. 0 Perform additional subsurface exploration surrounding the damsite to evaluate in detail the questions of seep- age around the abutments and to aid in construction management of stream underflow water and in design of the embankment underdrain system. 0 Perform additional borrow exploration and testing for select materials such as core and filter materials. 0 Study the effect on water treatability of not stripping the surface vegetation and topsoil from the reservoir area. 0 Conduct a sediment sampling study to provide data for reservoir sedimentation estimates. 11-2 Chapter 12 00 E31BLIOGRAPHY Aerial Photography, Eagle River Valley. Anchorage, Alaska: Air ?-Fo-to Tech, Inc.-Au-gust 1979. Alaska Department of Fish and Game. Letter to Anchorage Water & Sewer Utilities. November 4, 1980. Anchorage, Municipality of, Department of Administrative 5er- vices. Aerial Topographic Map,, Eagle River and Vicinity. Anchorag-e,A[aska. 1978. Anchorage Water Sources. Prepared for the Anchorage Water _0_t7it-y, and -C-entral-TTa-ska Utilities. Anchorage, Alaska: Tryck, Nyman & Hayes; Dames & Moore; and Leeds, Hill & Jewett. 1973. Brune, G. M. "Trap Efficiency of Reservoirs." Transactions of the American Geophysical Union. Vol. 34, No. 3, pp. 407-418. 1953. Carlson, Robert F. Estimate of Flood Frequency on the Eagle River, Alaska. Letter'Report to CT2-MHILL. 1980. Carlson, Robert F. Special Design Considerations for the Eagle River Dam and Reservoir. r Report to CH2M TTLE7. -f-980. Colby, B. R. "Relationship of Unmeasured Sediment Discharge to Mean Velocity." Transactions of the American Geophysical Union. Vol. -38, No. 5, pp. 707-717. 1957. Elmendorf AFB, Base Weather Station. Six-Hour Precipitation and Temperature Records of Flood Periods. Anchorage, Alaska. 19'80. Fling, R. F., Glacial. and Quaternary Geology. New York: John Wiley and Sons. 1971. Linsley, R. K., Jr., M. A. Kohler, and J. L. H. Paulhus. Hydrology f6r Engineers. 2nd ed. New York: McGraw Hill. 1975* Newmark, Nathan M. "Effects of Earthquakes on Dams and Embankments. Geotechnique. Vol. XV, No. 2, pp. 139-160. 1965. Preliminary Engineering Report, Eagle River Project, Anchorage, Alaska. Prepared for Anchora@e-Municipal Light and Power Utility. Anchorage, Alaska: R. W. Retherford Associates and Adams, Corthell, Lee, Wince and Associates. Federal Power Commission Project No. 2045. 1966. 12-1 Siegel, R. A. Computer Analysis of General Slope Stability Problems. West Lafayette, Indiana:- Purdue University Joint Highway Research Project. Technical Report No. 75-8. June 1975. Taylor, D.W. Fundamentals of Soil Mechanics. New York: John Wiley and Sons. Chapter 19. 1948. U.S. Army Corps of Engineers, Alaska District, in conjunction with the Municipality of Anchorage. Metropolitan Anchorage Urban Study. Vol. 2, Water Supply. 1979. U.S. Army Corps of Engineers. Feasibility Studies for Small Scale Hydropower Additions. Davis, California. July 1979. HEC-1 Flood Hydrograph Package, Users Manual. Davis, California'. January 1973. HEC-4 Monthly Streamflow Simulation, Users Manual. Davis, California. February 1971. HEC-3 Reservoir System Analysis for Conservation, 67 Users Manual. avis, Cal ifornia 1974. HEC-2 Water Surface Profiles, Users Manual. Davis, California. August 1979. Hydraulic Design of Spillways. Washington D.C. March 1965. 1 . National Program of Inspections of Dams. Vol. 1, Appendix D. "Reco mended Guidelines for Safety Inspections of Dams. 11 Washington D.C.: Department of the Army. 1975. U.S. Bureau of Reclamation. Design of Small Dams. Washington D.C.: Government Printing Office. 1974. esign of Small Dams. Washington D.C.: Govern- ment Printing Office. 1977. U.S. Geological Survey. Flood Characteristics of Alaskan Streams. Water Resources Ivestigations. Open-file Report 78-129. Prepared by R.O. Lamke. Flow Duration Curves, Eaqle River, Ship Creek, and Peters Creek, Alaska. August 1980. Generalized Geologic Map of the Eagle River Birchwood Area, Greater Anchorage Area Borough, Alaska. Open File Map. Prepared by H.R. Schmoll,E. Dobrovolony and C. Zenone. 1971. 12-2 Geology and Ground Water for Land Use Planninq in the Eagle River and Chugiak Area, Alaska. Open File Repoport 74-57. Prepared in cooperation with the Greater Anchorage Borough by C. Zenone, H. R. Schmoll, and E. DobrovoIny. Denver, Colorado (published by the Anchorage Area Borough). 1974. - . Maximum Annual Floods and Hourly Flow Data, Eagle River, Alaska August 1980. Physiographic Divisions of Alaska. Survey Profile Paper 482. Prepared by Clyde Wahrhaffig. 1965. Preliminary Geologic Map of the Middle Part of the Eagle River Valley, Municipality of Anchorage, Alaska. Open File Report 80-890. Prepared by H. 1. SchmoiT, E. Dob ovoIny, and C. A. Gardner. 1980. Reconnaissance Bedrock Geologic Map of the Chugach Mountains Near Anchorage, Alaska. Map MF-350. Prepared by Surficial Geophysical Data for Two Cross-Valle Lines in the Middle Eagle River Valley,Alaska. Open File Report 80-2000. Prepared in cooperation with the Municipality of Anchorage by by Larry L. Dearborn and Donald H. Schaefer. 1981. Surface Water Records of Cook Inlet Basin Through September 1978. Open File Report 78-498. 1978. Unevaluated Reconnaissance Report (December 1948) on Geology of Lower Eagle River Valley, Alaska. Open File Report 80-275. Prepared by A.F. Bateman, Jr. 1980. Water Resources Data for Alaska. Various years. U.S. National Weather Service, National Climatic Center. Climatological Data for Alaska, annual summaries 1916-1979. U.S. Weather Bureau. Probable Maximum Precipitation and Rainfall-Frequency Data for Alaska. Technical Paper 47 Washingtion D.C.: Government Printing Office. 1963. Probable Maximum Precipitation, Northwest States. Hydrometerological Report 43. Washington D.C.: Government Printing Office. 1966. Vanoni, V. A., ed. Sedimentation Engineering. New York: ASCE. pp. 745. 1975. Water Resources Atlas. Prepared for the U.S. Forest Service, Region x, Juneau, Alaska. Redding, California: Ott Water Engineers, Inc. April 1979. 12-3 I I Exhibit A Streamflows EAGLE RIVER MONTHLY- STk*LAMFL0(4 SIMULATION IRIAL NO.2 HISTORICAL ONLY. IYRA IMNIH, IANAL MXRCS,' NYk(j NYMXB NPASS IPCHC.4 IPCHS NSIA NCOMD NTNDM N' C S TY IGNRL NPROJ I YRPJ MTHF-J LYRPJ 1966 10 1 14 196 14' 1 0 0 C) 0 0 0 0 0 0, 0 MAXIMUM VOLUMES OF RECORIiEft FLOWS STA lo ill 12 1 3. 4 5 6 7 1-mo 6-MO 54-MO AV MO 771 707 190 13*7 ;,118 97 85 117 366 1507 2120 24 24 1593 2424 798.0 32.199 516 MINDjUh VOLUMES STA 10 11 12 1 2 3, 4 5 6 7 8 9 1-mo 6-Mo 54-MOI AV MO 771 155 86 54 39 26 36 61 82 '662 1290 874 430 26 322 21412, FR-1*L1ULNCY STATISTICS STA ITEM 1.0 11 12 1 2 3 4 5 6 ? 8 9 771- ME AN 2. 4 8 0 2.098 1.9.41 1.812 *Z28 1.720 1.843 2" . 3 6 2.973 3.228 3.201. 2. IV12 .1 :. 0. l';I'Z 0. 108'' 0.122 0.142 0.158 0.115 0.114 0.174 0.114 0.069 0.120 0. 1;'S C3 r 1*1 @* @, V SKEW 0.374 0 . 26 5. 0.350 0.217 --0. 10? 0.616 -0.745 -1.215 0.438 -0.1-27 --0*266 @0,233 INCRMT 3.'24 [email protected] 0.90 0.67 @0. 56 0. 54 0. 1 2. 43'@ 9.62 16.95 16.29,' 8,72 Yr-ARS 14 '14 14 14 14, 14 14 - 14 14 14 14 14 RAW@ CORRELATION COEFF ICIENTS FOR MONTH 10 ST A 771 WnH CURRENT MONTH' 771; 1.000 W I'l H PRFC EDIUG MONTH AT ABO VE STAI 1014 0.244 RAW COIRRELATION COEFFICIENTS FOR MONTH 11 STA 7-11 W ITH CURRE.NT MONT H 771. 1.000 ? WITH PRECEDING MONTH A1* ABOVE STATION 771 0.667 RAW 'CORRELATION COEFFICULNIS FOR MONT'll 12 STA 771 UITH CURKLN I MONTH "171 1.000 W I TH PRECEDING MDN*01 AT A Yi V El S TAT 10 14 7/1 0.6-12 PAW CORREA,'ITIUN C0i:+f:1CIF..N*1',S F:0P MOt4rH l J I H C URREN I MON H 1000 W I Fl P R, E:*. C E D I N G ri 0 NTFI AT U V L STA -1 1 u N 271 0 8,";3 RAW CORRELA110N (..(.)EFVIClENfS FOR MUNIH 2 STA 7@11 WITH CURRFNIf hON'lH 771 1.000 WITH FIRECEDIN6 h 0 N'l H Al ABOVE STATION 771 '0.912 RAW CORRELATION COLFF lCIENTS FOR MONTH 3 STA 771 W11H CURIRENT MONTH 771 1.000 WITH PRECEDING MONTH AT ABOVE STATION '771 0.866 RAW CORRELATION COE: FF ICI ENTS FOR MONTH 4 STA 771 WITH CURRENT M 0 NT H 771 1.000 WITH PRECEDING HONIH AT ABOVE STATION 771 0.449 RAW CORRELATION,COEFFICTEN'I.S FOR MONTH 5@, STA 771 WITH CURREN.-Il MOUTH 771 @1.000 WITH PRECEDING MONIH AT ABOVE STATION 7Y1 0.701 RAW CORRELAfION COEFFICIENTS FOR MONTH 6 STA 7.71 W IT H CURRENT MONTH 771 1.066 WITH PRECEDING MONTH AT ABOVE SIA'11014 771 0.520 RAW CORRELATION COEFFICIENIS FOR MONIH 7 STA @71 WITH CURRENI 14UN'tH .771 1.000 WITH PRECEDING MUNIH AT ABOVE STATION 771 0.673 RAW CORF"ELAI-100 COLFFICiENTS FOR MONTH 6 5 1 ri /7 1 Wl iH uURRENT MONI'll 771 1.000 Wl I H F'kf..CLl,lN6 MUNTH AT ABOVE STA 11 UN 77J. 0.791 RAW CORRELA,riot4 COEFFICIENT'S FOR hONiH Y Sl A 7.71 WITH CURRENT HOW'Fl 771 1.000 WITH PRECEDING MUNIH AT AbUVL STATION 771 0.682 RE'CORDLE, AND FZECONSTITUIED FLOWS STA YEAR 10 11 12, 1 3 4 b 6 7 a 9 i,u,rAL 771 1966 42t@ 162 83 -1 50 -0 51 2, 3 5 1150 1958 1177 7250 1858 77 1' 1967 342 103 77 67 51 53 75 1507 2116 2221 1593 8460 "171 1968 288 133 B2 72 64 61 63 356 @?61 1775 1450 476 5781 @@71 1.969 lb5 107 70 39 32 42 79 322 12b2 1564 074 457 4?93 771 1970 707 l?4 119 99 yo 85 78 218 1303 1241 588 5441 771 1971, 181 103 75 57 li 40 361 82 ';125 17.72 2002 552 5677 771 1.972 191 100 90 65 39 36 59 145 689 1747 1589 970 5720 771 1973 418 143 123 73 48 44 7.1 160 662 1290 1227 430 4689 771 1974 267 86 54 39 21 6 40 77 2.@2 921 1472 1489 1141 5884 771 1975 1-:13 1 123 81 48 4b 45 77 313 ',@46 1652 1307 756 5424 771 1?76 237 91 65 56 53 46 64 1 ;17 889 1615 1386 900 b579 771 1977 30.;'' iyo 130 94 79 62 78 249 13*33, 2120 2424 1100 8166 771 1976 460' 158 137 9 *? 79 72 246 816 1447 1528 971 6129 771 1979 324 116 72 65. 61. 69 117 3-66 100, 2 2001 2103 1098 7474 GENERATED FLOUS FOR PERIOD 1 STA YEAR 10 11 1? 1 2 3 4 5 6 7 8 9 TOTAL 771 1 251 114 78 40 23 36 23 35 572 .1146 1200 344 3862 771 2 179 100 62 3 6 @@l @q i4 189 673 1367 1246 1054 5010 771 3 289 114 so 52 41 42 79 323 769 1965 179@S tY7 3 6120 771 4 187 8 B 65 43 39 47 68 204 1055 .1774 14 b8 t@49 5577 771 5 339 130 81 68 60 48 68 207 840 1911 1690 W?() 6312 771 6 589 129 100 81 ';, 2 78 83 3t@2 901 1631 1469 362 5847 771 7 141 93 72 bi 48 41 55 205 713 1643 1786 lb03 6351 771, 8 264 115 83 48 .2Y 39 51 1152 756 1578 1498 ";ZS 4 5447 771 9 142 87 80 be 43 45 53 131 ;@ '17 6 1353 919 614 4301 771 10 229 97 64 42 41 40 52 129 899 1581 1144 6'? 7 4995 771 11 287 92 59 42 33 40 70 170 1070 1730 1721 ?81 6295 771 12 317 203 108 4 66 51 46 140 ?'/ 3 1849 16b8 838 6323 771 13 416 130 al 63 61 82 356 834 1560 1291 661 5616 771 14 360 101 60 36 32 31 43 322 1149 1673 1451 3.;, 5795 MAXIMUM VOLUMES FOR PERIOD 1 OF 14 YEARS OF SYNTHETIC FLOWS STA 10 11 12 1 3 4 5 6 7 8 9 I-MO 6-MU 54-MO AV MO 771 589 203 108 81. "@21 78 83 3to6 1149 1965 1793 lt@o@@ 196b 6115 29775 463 MINIMUM VOLUMES EJA 10 11 1? 1 2 3 4 5 6 a 9 I-MO 6-MO 54-MO AV MO 771 141 87 5@ 36 21 --)g 2 3 31@ @Y;121 1146 919 344 21 234 21112 G f N E P(i TED F L. 0 W 1-3 FO P PE f 10, El 51 A YEAR .1.0 1 2 3 4 11/1. is '67 11 6 39 7 -S 6 .8 TOTAL 771. 16 2 6 66 '47 G 1 1884 18@7 1089 6855 5- 4 38 -16 70 209 "Z 1 -14 4 1153 481 4684 771 1.7 2 a G 121 y 3 72 70 5:5 91 3 31 3 1.316 427 5361 771 18 3 72 142 104 72 48 47 50 12 3 8 6 2 1 to 96 1612 639 771 19 109 49 44 34 43 77 182 5667 771 ?91 1449 1134 720 4921 20 245 112 117 1011 107 5 60 1-111 6? 6 1 tp'/4 1414 885 5537 771 )1 1 s 9, @3 28y . 13-@l 2) 14 0 1898 982 7453 303 ill 84 '31 S 2 771 @;2 316 12 2, 83 61 43 52 64 236 1'25 4 1836 1868 1056 7041 77 1 "7 A I 2 3 102 43 771' 4 76 A9 3e 6 132 Y 4 14211 1386 558' 4956 ,, . 33/ 14S' 73' 66 57 68 77 3 2'j @71 25@ 2 14 913 1987 1569 1252 617 5573 62 42 24 39 38 70- @@84 1409 760 5263 771 26 7 2'/ v? 1 100 63 57 51 71 336 1093 204 2 0 4 2 1489 8241 771 27 454 1 (? 8'. 139 134 1111 94 70 21Y 1114 '1542 1358 659 6092 771 2 Q 476 -121 Be 85 58 49 101 346 12? 6 2112 2642 1619 8973 MAXIMUM F*OR PERIOD 2 OF,., 14 YEARS OF SYN-1HE'1IC FLOWS S TA 10 11 12 3 4 5 6 91 '1 M' 0 M 0 b4-MO AV mo 771 727 1.98 139' 1 34 111 94 1011 346 131"t 2140 2642 1619 2- 6 4 2 809t5 33393 516 MINIMUM VOLUMES c'T A lo 12 S 3 -1 5 6 S .9 1 MO 6@MO t@4-rHO AV MO 1 771 207 93 .49 42 2@ 38 38 70 676 1421 1134 4.27 24 2/ 4 21183 GENERATED FLOWS FOR PERIOD 3 STA YEAR 10 3 4 771. .29 '519 171' 145 92 52 6 9 TOTAL 30 214 t, 13'2"' 114 50 67 822 1742 1794. 789 6374 771. 31. 89 `/0 2 295 :1. 159' 1907 1646' 667 6485 181 86 64 40 28 3 5' 49- lbo 6 "" 8 1690 1240 768 5017 7@1 32 202 0 62. 51 36 40 91 314 C62 771 33 2'.?' 1463 14.92 720 5428 3 106 .58 6 51 77 771 34 23 8 92 2,68 1811 1330 658 561?0 771 141 69 49 49 56 1829 la?i I ,71 6222 @ 5 3 2 '@: 1?81 85 - 2 771. 36 3j/ 140 82 6-4 73 70 69 248 1'/ 15 1342 541 b7oo 771 37 323 1"3 1 61 56 As 77 -31Y 92@5 1401 152 5' 1089 6080 11.1 1.17" 107 12 22 4 21 1 148 .7 2t@43 22) 7 4 838 8583 771 403 '148 .92 73, 58 67 84 383 1179 771. 19'1@ 101 60 44 41 18 l? 22 2 2 1196 7722 771 33 51 241 98o 1808 1298 453 5512 771 40. 5 6 6 184 127 69 72 57 57 84 6-9 1 162t,' 1557: 949 5968 771 41 260 130 92 75 5*? 54 57, 99 lisi. 1 @'4 3 1576 857 6151 42 482 ti32 157 ill 104 94 233 1305 .1172 454 4989 MAXIMUM VO!-UMES F OR PE.RI'tili 3 - OF 14 YEARS OF S Y N 'I HETI C FLOWS STA '10 11 ,I f-) 771, 566 164 1.57 2 3 4 5 6 8 9 1 -Mo 6-MO 54-MO AV MO .117. 107 22, 109 421 1487 '-)'j 4 2-2 4 1196 2543 7966 33812 511 MINIMUM VOLUMES S TA 10 11 121 ? 3 4 5 6 7 8 9 6-MU 54-110 AV MO 771 181 86 60 40 28, 31.5 49 84 599 1305 11'/2 454 28 301 22Y58 GENERATED FLOWS FOR PLKIIOD 4 S TA Y F".. A R 10 12 1 3 43 "'42 6 7, 8 9 TOTAL 93 68 t. 9 4 82 1434 1214 506 4895 7 7 1. 44 1 11-1,3 '?9 49 3 4 771 45 60b 1 '23 7 9 3 5 441 3672 123 96 2 0 20 3 7 1764 1366 ',@2b6 /7 1 46. Be o 7 3-13 .121 4 2' 146S 6'/bl -1171 47 133 -19 6'i,` so lt@ 4 13 14@8 1757 820 51:5tia 771 -19 3 0,:- 1 J 45 1 @J'3 1 10@5 4" 460 136 9' 77 62 49 1 . 679' b';, 0 5 771 49 2Y 6, 116 96 76 7 64 102 3 1J. IS I "" @40 2 01,@ 6 15'24 669 6772 10 60. 09, 3 47 18,Z3 723 72186 771 5 1 194 99 5 2S - 11 77.1. 51 13i 94 58 38 33 39 63 1 '2 6 ;,30 1595 1363 612 4886 771 52 246 89 55 36 26 34 37 8,3 I.Y? 9 ib06 037 569 4097 771. 53 190 11.2 77 51 46 46 101 314 83111) lb96 1380 899 5647 771 54 454 1138 Be 60 44 44 6@2 -2 7 t@ 681. 1373 1372 838 5429 771 55 2 12 11.3 71 75 95 6 0) 324 13-51 '21 14 9 2353' 1707 8627 1313 771 56 236 12'? 106 70 52 57 71 17@. 12 t5 *3 2064 2950 8471 MAXIMUM VOLUMES FOR PER 1011 4 0 IF 14 YEARS OF SYNTHE (IC FLOWS STA 10 11 12 1 2 3 4 5 ..6 a 9 1 --mo .6-MO 54-MO AV Mo 771 512 194 106 88 1?9 358 -1361 2149 L" 9.5 0 1707 2950 siqo 31797 506 MINIMUM VOLUMES S IT A 10 11 12 1 2 3 4 5 6 8 9 1 --mo 6-MO '1@4-hu AV MO 771 135 79 49 34 20 28 -24 57 579 12 37, 83 7 441 20 .211 2065@? GENERATED FLOWS FOR PERIOD S STA YEAR 10 11 12 1 21 3 4 6 1-1 6 9 TOTAL 77 .1 57 239 ltj2 103 70 6 6 70 83 348 9?8 1841 1236 683 5889 771 58 292 140 128 140 10,2 @3 J.06 392, 10'1@3 169@ 1623 971 6736 771 59 308 156 1 A 119 104 98 85 3Ub 9 0 6 1670 2005 1137 703b 771 60 410 151 97 59 40 52 70 146 0 a Y 1806 1825 877 6422 771 61 221 112 Be 66 64 57 74 187 f3i3a 1644 1433 798 5,632 771 @62 337 1? 2 142 88 64 54 6 7 184 993 1621 1288 333 5343 771 63 2 4 21 113 117 87 74 69 107 415 1014 1562 1490 772 6062 771 64 288 116 97 81. 65 5 6 87 330- ;8 3 1573 1101 597 5174 771 65 216 93 55, 43 411 43 84 179 9 13 lb46 1201 582 4996 771. 66 600 226 210 1 Be 126 137 96 '`29 1440 1541 718 6363 771 67 288 134 101 69 52 -51 60 15@ 595 1351 1582 820 5259 771 68 28Y 12'/ 74 55 3/ 38 75 24b 966 1802 2398 1273 7379 771 69 606 162 90 83 53 48 65 15Y 1041 2051 1813 1021 7192 771. ' 76 505 13 4 90 70 @o 59 79 10 5,;, 1,.;181 1869 1285 7234 MAXIMUM VOLUMES FbR PLPIOD 5 OF 14. YEARS OF SYNTHElIC FLOWS STA 10 11 12 1 3 4 a 9 54-MO AV MO 1 --mo 6-MO 771 606 226 210 is's 126 107 415 1073 210 t@ 1 1285 2398 72? 1 31938 516 MINIMUM VOLUMES STA 10 11 12 1 2 3 4 6 7 a 9 1 ---MO 6-MO 54--MO AV MO 771 216 93 55 43 37 38 60 146 595 1351 1101 333 37 35Y 22197 GENERATED FLOWS FOR F-LRIOD 6 STA YEAR .10 11 12 1 2 3 4 5 6 7 a 9 TOTAL 771 71 276 1 lt@ 70 45 38 44 54 181 1224 730 860 4418 771 72 674 201 148 84 78 64 58 2@@'.@ 0 li% 6 itioo 1177 713 5848 771, 73 228 11 101 61 5b 50 62 2 3S 864 1445 1289 596 5105 771 74 4';, 4 113 73 54 45 47 42 68 '-.@ 2 6 155t5 1114 527 4838 771 75 1 tl@y 8.@ 53 40 33 43 47 278 9@:.9 l?47 2084 1113 6643 771 76 388 1' k 78 69 52 44 66 1Y4 12,128. 165/ 1837 971 6697 771 77 335 1 Ili, 4 121 95 106 65 101 3t; 1 9":)/) 1696 1465 609 6054, 771 78 23 "Y 2 108 74 58 3 42 91 23" 81 1608 1278 502 5089 771 79 315 14to 86 13 7 6@3 71 66 1,05 1 00 262 C. 66 41 39 70 343 1 0'@@ 1802, 1397 921 6133 -771. 0 1 7,k--'/ 19 1/ 1.59 119 70 1.04 A14 .1999 2261 1953 1071 ?322 77:1. 82 163 91 .66 55 47 64 06, .26b 10111 1*,@33 1971 780 6'3 4 771. 83 321 1'."B 98 62 52 59 7 201 137/ 1616 1107 t;943 771 84 451 1311 79 46 37 49 7 4 2'@@'," 82 1613 1096 843 5462 MAXIMUM VOLUMES FOR PERIOD, 6 OF 14 YEARS OF SYNTHETIC F`LOWS STA 10 ii 12 1 2 3 4 5 6 8 9 A ---MO 6-M0 54-MO AV MO 771 737 230 197 159 119 78 104 41.4 1999 22 6 1 0 8 4 1765 2 2 6 1 7861 35085 510 MINIMUM VOLUMES STA 10 11 12 1 2 3 4 5 6 7 a 9 1 do 6-M0 54-110 Av. mc) 771 159 80 5.3 40 29 39 42 68 726 1224 502 29 30@@ 20a94 G@-'NERATED FLOWS FOR PERIOD, 7 STA YEAR 10 11 12 1 3 4 6 7 a 9 TOTAL 9 5, 6 92 77 56 49 44 09 2 8@ 1 1'1@9 2018 2 2 6 5 1447 7839 771 86 288 96 34 67 44V 42 65 32:j: 2117 2558 1682 8695 771. 0.7 2.7 7 1.12 37 al 61 56 55 187 1? 5? 1953 1807 709 6342 771 FIG 254 12,? 94- 67 51 51 94 338 (408 1536 1429 1145 5994 771. 89 .436 199 151 102 62 66 122 420 1.040 1841 16@4 822 692tS 2 16 ?,1 35 0, ?3 14'/7 1438 784 5255 771@ 90 56 29 39 43 155 91 269 120 73 52 38 46 60 189 1 0.Z 2 1625 1726 909 6 l';' 9 771. 92. 1815 120 86 74 74 64 93 246 3 1322 949 501 4587 771 93 221 9 .12,18 89 69 53 46 47 2 1? 6 t. 1910 1611 8216 6079 771 94 5 ? 1 19 3 126 119 105 es 96 262 Jill-18 2042 1964 13'6 5 771 95 203 ill") 71 46 43 5 3 62 241 924 1924 1867 988 6 t 3';' 771 96 316 1 ','.o 4 96 66 67 65 69 1 si@ 1.012 l;4.8 1315 912 6005 771 97 346 96 64 48 36 @8 E1,32 3,10 15 12 199Y 1561 816 6Y76 -771 98 430 12, 1 74 46 30 35 62 206 9101.4 1423 1252 996 5619 MAXIMUM VOLUMES FOR,PFRIOD OF 14 YEARS OF.SYNTHETIC FLOWS G T A 10 11 12 1. 3 4 5 6 8 9 1-mo 6-MC) 54-MU AV KO 771 591 199 I'll 119 105 88 122 420 15,12 2 11 2 5,i 8 1682 2558 8280 35367 540 MINIMUM VOLUMES STA 1.0 11 12 1 3 4 t; 6 7 a 9 1 --MO 6-M0 "-4-140 AV MU 771 185, 90 56 35 29 43 155 775 1322 .949 501 29 291 2 3 1 )0 GENERATED FLOWS FOR PERIOD 8 T A YEAR 10 11 12 1 3 4 6 7 8 9 TOTAL 771 99 4 165 58' .461., 45 66 3 1 ll@iqy 1703 1977 968 7384 7 1. 100 411 1.18 1018 84 71 6 1 29 .1 (,9 2 1904 2062 1019 'Z204 771 .1. 0 1 1 B I @?2 6 2 51 38 106 8 0 15 1 t. 2, 9 1306 569 4851 77.1 10,2 3 Y -(00 137 :103 97 1. -1) 1 Q 3 34C', 16", 1322 1045 6299 7711, 103 95 6 0 5'/ 41 2 0.@ It-Y 4 1542' 479 5961 10,11 15, 0 .1 41. 42 3 1'-. 160,:, 1583 739 5518 7:1. 1. 0 11-1) f.3 4 A 11 ?'17 1145 630 4B27 .1. :il.l 113 114 4 1521 8 42 tj9l?8 :1.07 2 i IJ -1 L 2 "q A 41 ,09 1 ll@ 1 19 3 '17 674 6665 1 '2 B -7 IS 7 1 7028 2 1493 731 1. J I Cl ? -'19 699 0 1. 5 8 12 1 1. 61 1. :1 Y 6 2 6/83 7 1 10 0 900 5 4 8 74-7 1. 8 G S L: J 14 YE,"RS Q S N I i P F", C 1 1':! I I I.,,, 1. , 1 .1, . .1. M 0 6--:hO 4 1 t, I --Mcj AV MO: 7 1. 7 -D 5 1 j, 1 110 10 1. '.;'B 340 1 1 2".7 4 3 367S' '3 3 22 7 530 KINIMUM VOLUMES ,",I A lo 1. 1. a 1. .-hC) 6--MO t@4 -iHO A. V 140 771 35 27 51 36 32 3'3 V/ 106 6. 1 I'Y7 1080 4 7 9 2 2,86 22 13 (3 E N E R A TE D FL 0 W S FOR PER 10 D 9 Sl A Y EAR 1 11 12 1. .3 4 6 .7 S 9 TOTAL - 113 0 12 6 75 5 A 7 71 771 114 3TD 1()? 75, 85 78 75 97 28'. 1261, 1 Y.'/ 2 23 4 7 2096, 8820 771 115 4@@ ' :123 80 49 34 45 99 3 6 10 16 1'/ T/-, 1847. 680 6t@23 771 1.16 276 120 q-) 63 53 1 4' 1 1? :1009 16 1355 523 b3t2 1177 2, 130 84 53 Fj 2 5 1 (1.13 7 71 116Y1 1699 622 .5(323 7 1 11 10 183 114 106 92' 79 03 @-j 4 1 T3 S 943 4613 4404 63 P:,?. 1,,@ 9 6 23-14 1539 /073 771 119 33 .106 73 44 3 3 tJ 46 3 :16 0, 104 68 Ll, 0 2 73 @@v.,-6 I B1@6 1949 1487 729t@ 771 1-710 6@ L2 771, 1.21. t; 3 9 1:1 64* 46 34. 40 66 -714 .11,66 1',114 1970, 770 6834 el 1 192 771 12-1 1 118 97 108 99 1.3 IS97 2096. 1,176 6606' 771' 1. '5 1130 6903 112 75 42 29 3 57 111 1395 192 7 2128 77 1 1.24 39 6 10? 79 61 62 5/ 1 1 4'@ 6 11, 3 13,175 1409 828 5275 125 4 83 :161 ll@ 94 7tj 62 9'@? 252 1565; 1945 909 6b22 11 77 1 1. 8 8 12," 85 619 63 65 1 a 0 :1. 04, Ai 1';, 3 0 1365 4@1 7 6125 M A X I'M U M VOLUMES FOR PER1 0 11 OF 14 YEARS OF SYNTHETIC F L 0 W,:)' 5 T A 10 11 12 1 2, 3 4 -@5 9 9 1 --mo 6--MO 54-MO AV mo B50 771 161 IlB 97 foe 99 99 376 .1264 19 2096 2347 8403 34479 529 MINIMUM VOLUMES STA 1.0 it 11.1 1 3 1 t. 6 a 9 I--MO 6--MO t#4--HU AV MO 771 183 106 64 42 29 31: 42 63 6153 13 38 fa4@3 463 -.-19; 298 2:2 2 83 GENERATED FLOWS FOR PLPIOD 10 S TA YEAR to 11 12 1 3 4 6 - 7 a 9 TOTAL 771 127 2@S6 I C1.6 66 .53 t@9 56 4 5 L, 1 -`6 106@7 922 443 3690 771 -85 141, 104 02 58 55 99 '2 -8 4 1 2 2070 4 6 22 782 7574 1.29 63*3 i 1') 9 123' 69 49 41 10 5 6 1 6';l 2 1731 1066 6904 771. 70 -771. 1.30 2 0 :1, 0 72 80 68 64 74 3121 J 201 2026 1718 724 6641 ;71 1. 3.L 190 11 ""1 95 79 6 5 5'/ . 45@ 176 1 @Sl 6 1001-71 856 4832 771 132 291 114 68 64 40, 07 2' li 11116 2 '0 4 1906 1480 7800 133. 288 1.19 98-/ 76 ,171 52 45: 61 214 1@29 1706 974 624/ 771. 134 '186 7 97 72 72 62 74 211 14114 1*?10 1577 908 6922 771 1.35 8 y 6 7 2 43, 34 45 40. 1 6'@ 1414 1457 354 4*;74 771 1.36 2 3 5 1 89 86 34 7:3 74 2 6? 13 J. 1499 1267 479 5142 25 4 9 603 5283 771 1.37 2`37 1211 87 62, 50 56 0 1607 1247 771 138 1 It. t) 1015 76 48 49 5t5 6,1 213 5 122 2067 2040 958 7093 771. 139 21 ? 0 113 75 68 52 45 77 3S6 02 to 2039 2040 1015 6Y75 771 140 20'j 1@2 5@ 45 44 58 94 34Y 1@'5 2 '2167 2347 1096 7504 MAXTMUM VOLUMES FOR PERIOD 10 OF 14 YEARS OF SYNTHEI Ic FL 0 W STA 10 11 11. 1 3 6 H 9 1 --mo 6--MO 54-MO AV MO 4 771 633 159 1.23 86 84 T3 99 356 1. 1116 2'. (1-1 2 1480 2462 7384 33215 520 MINIMUM VOLUMLS 3 6 -7 P , 91 1 I__Mo 6-mo No 771 155 '86 j 43 34 40 al 556 106/1 354 34 329 22 C, 8 tj GENERATED FLOWS FOR F'LkiOL' 11 STA Y 17 A- R I :L 1 12 1 3 4 .5 6 9 1 OTAL 771 1.41 319 124 -61 '34 4-1 40 58 1'/ 1 "1 .1, 3 1150' 1070. 857 4589 771 142 311 1 .107 89 61 68 51 149 8 9 1305 797 349 4022 771 143 223 1'.@ 105 li2 11,4 104 00 250 7 7 1885 1350 529 5784 771 144 2110 '30 89 69 4.9 52 09 34Y .1226 2084 1651' 643 6611 771 14 5) 239 00 59 44 41 @o a 59 261@ 0 11405 1392 5@i 4875 771 '_I A :1 0 z - 46 68 @9 lf/y 21 3 1628 1448 670; 5838 771 147 432 1;'@; @1 '65 48 48 79 159 029 1681 1452 BIB 5832 771 148 208 74 69 67 73 104 1001 1309 1025, 416 4819 771 149 2) 4 1 P 6 122 72 53 75 07 229 10 92 1 )'7 4 1872 1033 6869 771 150 296 111.4 128. 110 89 73' 02 294 12 25' 1571 1601 .511 6124 771 151 '@164 40 32 39 30 270 10t...9 1412 934 405 4693 9? 59 771 152 444 161 110 80 .59, 42 30 145 1114 2161 1711 1180 7245 771 153 3 2;' 11 @84 80 74, 72 .275 (344 1 *;139 1326 494 54-V6 771 154@@ 220 98 62, 58. 57 66 125 19 16-11 1276@, 1114 5664 MAXIMUM VOLUMES FOR PFRIOD 11 OF 14 YEARS OF 'SYNTHETIC FLOWS STA 10 .11" .12 11 2' 3 .4 5 9 1-mo 6-.MO 54-MO AV MID 771 444, 186 128@ 112 11.4' 104 104 349 1226 2161 1872 1180 2161 6638 29780 467 MINIMUM VOLUMES STA 10 it 12 1 2 3, 4 5 6 7 a 9 1-MO 6-MO 54-MO AV MO 771 208 '80 59, .40 32, @q 3 R 125 589 1150 797 349 32 334 21257 GENERATErl FLOWS-,FOR hRIDD 12 STA YEAR. 10 11 12 1 2 3 4 .5 6 7 8 TOTAL 771 155 189 .100 @2 60 3,6 33 60, 129 9 t_-) 1 1746 1734 530 5644 771 1'56 671 192 105 67 48 45 77 260 900 1791 1-9 2 3 1287 7446 771 157 208 1015 84 .63 79 88 65 251 I'll.91 2507 1931 9622 771. 158 7*17 148 83 , 5 3' 49 46 59 1? 1 .1062 1Y99 2305 851 7343 771 159 854 2 0..? 159 133 .99 99 74 208. @ 9'5 5 2150. 2256 900 8094 771. 160- 131 P,';, 73 64 44 41 85 356 11: '5'5 2312 3131 1301 9185 771 161 201 111'1@ 59 41 37 44 64 171 H 1) 1649 1@20 850 6007 @771 162 246 1.12 96 .75 78 510 46 210 93-Al 1636 1762 1033 6298 771 163 4 9';l .1.2 13 140 90 56 47 04 262 428 14'," 9 1168 920 5584 771 164 26Y 10 47 27 34 24 18 91117 1B15 2008 551 5814 771 165 3 11? '1215, 102 75 70 62 60 251 14 9 1622 1460 720 5644 771 166 163' 6 1? 5@ 43 3b 48 62 278' 927 1,;, 6 6 2021 1736 7210 771. 1,67 .?9 126 87 50 49 4 2 5V 27t U1.33 177'/ 1773 766 6 1 1, 3 771 168 260 1".1, 76 47 47 43, 56 304 30 1802 2039 1269 6946 MAXIMUM VOLUMES FOR Rl Cl D121 0 F 14 YEARS OF SYNTHETIC FLOWS STA 10 11 12 1. 3 4 5 6 9 1 --mo 6-MO, 54-Mli AV MO 1 854 213 11-'19 1. "K 3 99 99 3 1581 2's 0..' ..-i 31 1931 3131 9628 40689 577 MINIMUM VOLUMES S T A 'j() 8 9 1__-MO 6--MO b4-110 AV Plu 77 1 1.31 .19 41. 6 2e 'C' 1479 1168 530 to 216 5 [7 I OWS FOP PLk',:0f.1 I Yin. "114;' .11 169 V: 12' 1 -.3 i - 1 6 /i 1968 1 -3 15, 1 5812 77 1. 1-0 301 :1 "y 10 4 ? 3 1 103 306 J. 0 () 6 1,/61 10120 354 61@35 r;q . .: -@9 -11 -11. 0.@ - 1U22 1359 1 1, -@ 1. 1 (8 () 44 41 5 J, 8,/ 343 4363 771 1.72 '2 ?.@ I @@ 6 103 65 65 54 E@ -- 3261* 6 1? 1 "?, 8 1038 351 4657 771. 173 1 121 0 8 55 L. 18 36 4 0 21-19 0'.: 17 3 6 1892 868 6206 771. :1.74 25-@ 9 59 46 38 0 2, 4 6 si 1 1229 1389 530 45?3 771. :1.75 3,"3 1..'? (s 133 105 117 96 5 226 1 6 1736 1368 494 5759 .t 0 Y 980 771 176 306 84 75 67 58 70 214 P, r-; 16.1.4 1753 611b "I - - 2028 611 1 )1 .1.77 242 9 13 71 39 31 40 6;c') 172 *?86 1816 6002 771 178 3 3 6 '.k2lk 79 70 5y 54 74 2,43 1? 4 9 1370 499 t5412 1.4 - .: 77@. 1.79 2 L 102 -32 66 99 2? 4 QAA I A94 1660 670 6071 771. 1.80 3 () Ij @@26 101 53 49 5V 63 148 11 ), 7 1607 1491 972 6149 771 101 26to 103 73 56 41 42 @81 202 913 1511 1447 934 5668 77 1 182 3813 9 t,; 63 41 34 45 94 379 97-41 1681 1498 738 6025 MAXIMUM@ VOLUMES FOR PERIOD 1@5 OF' 14 YEAkS OF SYNTHETIC FLOWS STA 10 11 12 V 2 3 4 5 6 7 8 9 1-ho 6-MO 54-MO AV MO 771 , 383 196 133 105 117 96 103 379 1177 1968 2028 980 2028. 6064 29245 470 MINIMUM VOLUMES STA 10 11 12 1 2 3 4 5 7 8 9 I-KO 6-MO 54-MO AV MO 771 120 83 55 36 is 36 48 B7 579 1229 103B 343 IS 276 20699 GENERATED FLOWS FOR PERIOD 14 STA YEAR 10 11 12 2 3 4 5 6 7 8 9 TOTAL .771 183 334 110 93 76 44 40 54 140 754 1325 821 590 4381 771 184 306 142 12 '2 86,- 69 64 99 338 912 17'Z1 1662 700 6271 771 185 389 145 85 63 44 46 64 206 795 1771' 1,;@ 5 5 1253 6616 771 311 135' 96" 55 55 52 so 314 879 1974 2395 1142 7496 771' 187 419 ill 88 52 43 43 74 267 1046 1564 1283 853 5843 771 I8F* 242 127 .96 48 41 46 40@ 115 1021 1950 17j2 772 6250 771 181@ 241 125 79' .49 40 47 69 147 926 1556 1246 598 5117 771 190 274 1 '13 71 51 49 46 53 157 697 1439 1351 849 5160 771 191 261 118 59 52 37 46 104 2-51 1 8,; 4 1407 1422 380 4991 771 192 606 246 192 152 98 92 915 392 1397 2052 2060 1152 8534 771 193 511 149 129 84 59 63 318 '685 1533 1586 735 5933 771 194 447 2123 131 93 69 63 83 264 820 1691 1320 822 6026 -771 195 167 67 50 39 27 33 50 296,-, 912 1512 1794 970 5925 7 7 1 196 208 106 70 so 42 43 46 165 967 1860 1407 1048 6020 MAXIMUM VCJLUhES'FOR PERIOD 14 OF 14 YEARS OF S YNTHE'l I C F LOWS 1 -7 S'r 10 11 1 2 3 4 5 1 a 9 1. --- d 0 6-MO 54-HO AV.MO 9" 9@ 606 246 192 15 2 104 392 1397 2052 2 395 1253 2395 7564 31830 503 MINIMUM VOLUhES 1w; 11' 12 .1 1. 4 8 9 1 --tio 6--HO 54-HO AV MO 27 33 -4v I 1 15 13 21 @5 380 27 27ti 22629 I I Exhibit B Reservoir Operations HEC-3 computer printout for the 73 cfs (47 mgd) flrm-yield reservoir RESERVOIR SYSTEM ANALYSIS * 723-X6-L2030 I JULY 1974 * EAGLE RIVER WATER SUPPLY STUDY RESERVOIR OPERATION ANALYSIS GATES OPEN JUN I-SEP I NYRS IYR NL ICONS IDVSP IPWPR IDVPR IFLOW JUF'QI 46 1965 4 0 0 0 0 1 0 CLOCL CFLOD IUNIT METRC CNSTI ENSTO CCFS GUNIT CAC", VUHNIT 1PRNT 1PRL !PWKW 1UPDT !POST 1.00 1.00 0 0 1#000 10000 1.000 CFS 1.000 ACFT -1 0 0 0 0 IRG(I)= 0 IRG(2)= 0 IRG(3)= 0 IRG(4)= 0 IRG(5)= 0 IRG(6)= 0 IRG(7)= 0 IRG(B)= 0 IRG(9)= 0 IRG(10)= 1 NPER= 12 IPERA= 10 PERIOD OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP NDAYS 31 30 31 31 28 31 30 31 30 31 31 30 EVP Otoo 0.00 0.00 0.00 0.00 0.00 oloo 0.00 0.00 0.00 0*00 0400 CONTROL POINT SEQUENCE CP NO I LOWER DAMSITE MDNST MDIV MRES MPWR NTSRV IPRN NFLW QDV QMN QM2 QMxx 2 1 1 0 0 0 0 31. 70* 0.1000000. RESERVOIR DATA% INITIAL STOR 13300. CEVAP = 1.000 OLKG 0. ISRCH 0 S T 0 R A 6 E S OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP LEVEL 4 39300. 39300, 39300, 39300* 39300.. 39300* 39300. 39300.- 13300* 13300o 39300* 39300. LEVEL 3 39300* 39300* 39300o 39300* 39300. 39300, 39300. 39300* 13300t 13300o 39300* 39300, LEVEL 2 13300. 13300. 13300. 13300* 13300. 13300* 13300o 13300. 13300. 13300* 13300. 13300. LEVEL 1 13300. 13300, 13300, 13300. 13300. 13300. 13300. 13300# 13300# 13300, 13300* 13300, STOR 1000. 2000. 4000. 8000. 12000. 15000* 21000, 27000, 35000. 50000. AREA 150.0 237.0 350.0 675*0 91000 1030*0 1320*0 1690*0 2050.0 2430.0 OCAP 10000. 20000o 30000. 40000o 50000, 60000. 80000, 100000* 150000* 200000* ELEV 287*00 292.80 300,00 308.00 333400 316.00 320*30 325.10 329.40 336olO CP NO 2 DOWNSTREAM MDNST MDIV MRES MPWR NTSRV IPRN NFLW QDV QMN QM2 QMxx -1 1 0 0 0 0 1 -1. 0. 0.1000000. MG AND RTIO= 1 0.000 DIVERSION-1.000 TIMES DIVERSION AT I I OFLOW REQUIREMENTS AT I MULTIPLIED BY 1.019 IANNUAL. INPUT DATA FOR 1965 **INFLOWS S C TA 1 324, 1 2@.'J. 90. 67. 56. 54. 71. 243. 962. 11495. 1628, 872. ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTY AND POWER IN THOUSAND KWH I-ANNUAL INPUT DATA FOR 1966 **INFLOWS STA 1 425. 162. 83. 51, 50. 50. 51. 235'. 1150. 1858. -1958, 1177. ALL FLOWS IN CFSt STORAGES AND EVAP IN ACFTP AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1967 **INFLOWS STA 1 342. 103. 77* 67. 51. 53. 75, 255. 1507. 2116. 2221o 1593, ALL FLOWS IN CFS r STORAGES AND EVAP IN ACFTr AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1968 **INFLOWS STA 1 288* 133* 82. 72. 64. 61. 63. 356. 961. 1775. 1450. 476* ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTv AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1969 **INFLOWS STA 1 1550 107. 70. 39. 32. 42. 79. 322. 1252. 1564. 874o 457* ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTr AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1970 **INFLOWS STA 1 707. 174. 119. 99# 90. 815 . 78. 218. 739. 1303. 1241o 588. ALL FLOWS IN CFSP STORAGES AND EVAP IN AC;F,rt AND POWER IN THOUSAND KWH I.ANNUAL INPUT DATA FOR 1971 **INFLOWS STA 1 181. 103. 75. 57. 52. 40. 36. 82. 725. 1772. 2002. 552, ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTP AND POWER IN THOUSAND KWH 1ANNUAL INPUT DATA FOR 1972 **INFLOWS STA 1 191. 100. 90. 65. 39. 36. 59. 145. 689. 1747. 1589, 970, AL.L. FLOWS IN CFSY STORAGES AND EVAP IN ACFTP AND POWER IN THOUSAND KWH 1ANNUAL INPUT DATA FOR 1973 **INFLOWS STA 1 418. 143. 123. 73. 48# 44. 71. 1.60. 662. 1290. 1227. 430. ALL FLOWS IN CFSP STORAGES AND EVAF' IN ACFTY AND F'UWFR IN THOUSAND KWH 1ANNUAL INPUT DATA FOR 1974 -1*1NFLOWS STA 1 267. 86. 54. 39. 26. 40. 77. 272. 921. 1472. 1489. 1141* ALL. FLOWS IN CFS? STORAGES AND EVAP IN ACFTY AND POWER IN THOUSAND KWH 1ANNUAL INPUT DATA FOR 1975 **INFLOWS STA 1 231. 123. al. 48. 45. 45 . 77. 313. 746. 1652. 1.307. 756. ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTY AND POWER IN THOUSAND KWH I-ANNUAL INPUT DATA FOR 1976 **INFLOWS STA 1 237. 91. 65. 56. 53. 46. 64. 177. 8894 1615. 1386. 900. ALL. FLOWS IN CFSY STORAGES AND EVAP IN ACFTr AND POWER IN 1HUUSAND KWH 1ANNUAL INPUT DATA FOR 1977 **INFLOWS STA 1 307. 190. 130. 944 79, 62* 78# 249. 1333. 2120. 2424# 1100. ALL FLOWS IN CFSt STORAGES AND EVAP IN At.:F'fv AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1978 **INFLOWS STA 1 460* 158. 137. Ila. 97. 79. 72. 246. 816. 1447. 1528- 971. ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTY AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1979 **INFL.OWS STA 1 324. 116. 72. 65. 61. 69. 117. 36A. 1082. 2001. 2103. 109B. AL-L FLOWS IN CFSY STORAGES AND EVAP IN ACFTY AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1980 **INFLOWS c' 251. 114. '.""3. 35. 572. 1146. 1200o 344. )TA 1 78. 40. 23. 36. ALL FLOWS IN CFSt STORAGES AND EVAP IN ACFTP AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1981 **INFLOWS STA 1 179. 100. 62. 36. 21. 29. 54. 189. 6*;?Z. 1367. 1246t 1054. ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTP AND POWER IN THOUSAND KWH IANNUAL INPUf DATA FOR 1982 **INFLOWS STA 1 589. 129. 1.00. 81. 72. 78* 83. 352. 901. 1631. 1469. 362. ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTY AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1983 **INFLOWS STA 1 141. 93. 72. 51. 48. 41. 55. 20' 5. 713. 1643. 1786o 1503. ALL FLOWS IN CFSY STORAGES AND EVAP IN ACFTq AND POWFR 1N THOUSAND KWH IANNUAL INPUT DATA FOR 1984 **INFLOWS STA 1 372. 142. 104. 72. 48. 4? 50. 123. 862. 1596. 1612* 639. ALL FLOWS IN CFSP STORAGES AND EVAP IN AC;VT, AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1?85 **INFLOWS STA 1 289. 109. 49, 44. 34. 43. 77. 182. 791. 1449. 1134. 720. ALL FLOWS IN CFSt STORAGES AND EVAP IN ACFTr AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1986 **INFLOWS STA 1 337. 145. 73. 66, 57. 68. 77. 3 25 . 987. 1569. 1252. 617. ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTY AND POWER IN THOUSAND KWH .IANNUAL INPUT DATA FOR lqe7 **INFLOWS S TA 1 214. 93. 62 42. 24. 39. 3W. @/o. 784. 1728. 1409- 760. ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTr ANY) POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR l9eB **INFLOWS STA 1 245. 132. 114. 89. 70. 62. 99. 295. 1159. 1907. 1646. 667. ALL FLOWS IN CFSY STORAGES AND EVAP IN ACFTY AND POWER IN THOUSAND KWH 1ANNUAL INPUT DATA FOR IY89 **INFLUW5 STA 1 181. 86. 64. 40. 28. 35. 41?. 158. 678* 1,690. 1240, 768, ALL FLOWS IN CFSY STORAGES AND EVAP IN ACFTY AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1990 **INFLOWS STA 1 242. 153. 93. 68# 59. 54. 56. 234. 782, 1434. 1214o 506. ALL FLOWS IN CFSY STORAGES AND EVAP IN ACFTP AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1991 **INFLOWS STA 1 16*3. 79. 49. 34. 20* 28. 24* 57. 605, 1237. 935. 441. ALL FLOWS IN CFSv STORAGES AND EVAP IN ACFTP AND POWER IN THOUSAND KWH 1ANNUAL INPUT DATA FOR 1992 **INFLOWS STA 1 512. 194. 99. 75. 61. 60. 89. 253. 1347. 1873* 2000. 723. ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTY AND POWER IN THOUSAND KWH 1ANNUAL INPUT DATA FOR 1993 **INFLOWS STA 1 135. 94. 58. 38. 33. 39. 63. 126. 730* 1595. 1363. 612. ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTP AND POWER IN THOUSAND KWH 1ANNUAL INPUT VATA FOR 1994 **INFLOWS STA 1 246. 89. 55. 36. 26. 34. 37. 83. 579* 1506. 837. 569. ALL FLOWS IN CFSt STORAGES AND EVAP IN ACFTP AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1.995 **INFLOWS STA 1 337. 172. 142. as. 64. 54. 67. 184. 993. 1621. 1288. 333. ALL FLOWS IN CFSP STORAGES-AND EVAP IN ACFTY AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1996 **INFLOWS STA 1 242. 113. 117. 87. 74. 69. 107. 415. 1014. 1562. 1490. 772, ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTP AND POWER IN T14OUSAND KWH IANNUAL INPUT DATA FOR 1997 **INFLOWS STA 1 436. 199. 151. 102. 62. 66. 122. 420. 1040. 1841. 1664. 822o ALL.. FLOWS IN CFSY STORAGES AND EVAP IN ACFTp AND POWEk IN THOUSAND KWH IANNUAL INPUT DATA FOR 1990 **INFLOWS STA 1 216, 904 56. 35, 29s 3?. 43. 155. 893. 1477. 1438. 784. ALL FLOWS IN CFSP STORAGES AND EVAP IN A(.'F,rp AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1999 **INFLOWS STA 1 440. 205. 117. 87. 73. 83. 98. 339. 764. 1299. 1080. 900. ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTY AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 2000 **INFLOWS STA 1 203. 87. 51* 36. 32. 33. 47. 204. 167S. 2121. 2743. 1885. ALL- FLOWS IN CFSP STORAGES AND EVAP IN ACFTY AND POWER IN THOUSAND KWH 1ANNUAL INPUT DATA FOR 2001 **INFLOWS STA 1 210. 130. 89. 69. 49. 52. 89. 349. 1226. 2084. 1621. 643. ALL FLOWS IN CFSY STORAGES AND EVAP IN ACFTt AND POWER IN THOUSAND KWH 1ANNUAL INPUT DATA FOR 2002 **INFLOWS STA 1 239. 80. 59. 44. 41.. 50. 59. 205. 770, 1405. 1392. 531.1 ALL FLOWS IN CFS? STORAGES AND EVAF' IN ACFTt AND POWER IN THOUSAND KWH 1ANNUAL INPUT DATA FOR 2003 **INFLOWS STA I 4c?7. 213. 140. 90. 56. 47. 84. 262. 628* 1479. 1168. 920. ALL FLOWS IN CFSY STORAGES AND EVAP IN ACFTr AND POWER IN THOUSAND KWH 1ANNUAL INPUT DATA FOR 2004 **INFLOWS STA 1 269. 107. 67. 47. 27. 34. 24. 18. 847. 1815. 2008. 551o ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTr AND POWER IN IHOLISAND KWH 1ANNUAL INPUT DATA FOR 2005 **INFLOWS STA 1 301. 129. 103. 94. 77. al. 1,03. 306. 1006. 1761. 1820. 354, ALL FLOWS IN CFSY STORAGES AND EVAP IN A1:F*(y AND POWER IN THOUSAND KWH ]ANNUAL INPUT DATA FOR 2006 **INFLOWS STA 1 1.80. 85. 59. 44. 28. 41. 56. 87. 579. 1522, 1359. 343. ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTY AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 2007 **INFLOWS STA 1 297. 1.96. 103. 65s 65. 54. 87. 326. 692. 11483. 1038. 351. ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTv AND POWER IN THOUSAND KWH 1ANNUAL INPUT DATA FOR 2008 **INFLOWS STA 1 120* 83. 55. 36. 18. 36. 48. 22r/. 1035. 1786. 1892. 868. ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTP AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 2009 **INFLOWS STA 1 447. 223. 131. 93. 69o 63. 83. 264o 820. 1691. 1320. 822. ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTP AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 2010 **INFLOWS STA 1 167. 67. 50. 39. 27. 33 . 58. 296. 912. 1512. 1794. 970. ALL FLOWS IN (':FSt STORAGES AND EVAP IN ACFTY AN)) POWER IN THOUSAND KWH AVERAGES FOR PERIOD OF OPERATION 1965 - 2010 1 LOWER DAMSITE LOC FLW 486. UNREG 486. INFLOW 486. REQ DIV 30.9 DIVERSN 30.9 SHORTGE 0.0 EVAPO 0. CSV REL 104. RIV FLW 455. DES FLW 104. SHORTGE 0. 2 DOWNSTREAM L.OC FLW 0. UNREG 486. INFLOW 455. REQ DIV -30.9 DIVERSN -3009 SHORTGE 0.0 RIV FLW 486. DES FLW 0. SHORTGE 0. DIVERSION SHORTAGE INDEX 1 0.000 2 -1.000 DES FLOW SHORTAGE INDEX 1 0.000 2 -1.000 MIN FLOW SHORTAGE INDEX 1 -1.000 2 -1.000 DIVRSION SHORTAGES DES FLOW SHORTAGES MIN FLOW SHORTAGES SYS PWR SHORTAGES AT S11E PWR SHRTGS STA NO MAX NO MAX NO MAX NO MAX NO MAX 1 0 0. 0 0. 0 0. 0 0. 0 0. 2 0 0. 0 0. 0 0. 0 0. STORAGE FREQUENCY PER 46 YEARS AT LOCATION 1 CONS POOL OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP 99-100 PC T 45 '2 0 6 0 0 0 0 3 46 46 46 46 95- 99 PCT 1 10 6 2 0 0 0 0 0 0 0 0 90- 95 PCT 0 16 11 6 1 0 0 3 0 0 0 0 80-- 90 PC T 0 0 20 13 9 1. 0 9 0 0 0 0 70- 80 PC T 0 0 3 11 10 7 3 2 0 0 0 0 60--- 70 PC T 0 0 0 14 9 10 9 6 0 0 0 40-- 60 PC T 0 0 0 0 17 16 13 10 0 0 0 20- 40 PC T 0 0 0 0 0 12 20 8 0 0 0 1. --- 20 PC 1' 0 0 0 0 0 0 1 t'. 0 0 0 0 0-- 1 PCT 0 0 0 0 0 0 0 0 0 0 EAGLE RIVER WATER SUPPLY STUDY RESERVOIR OPERATION ANALYSIS GATES OPEN JUN 1-SEP I RESERVOIR DATA .............................................. + CP NO 1 LOWER DAMSITE + .............................................. N MONTH STORAGE ELEV INFLOW OUTFLOW EVAP GEN PWR /23X AC-FT FT CFSCFS AC-F*r . -0 11- ,vv llw" YR 1965 OCT 26936. 325.05 324. 71* 0. NOV 28470. 325.89 128. 71* 0. DEC 27718. 325.49 90. 71. 0. JAN 25552. 323.94 67. 71. 0. FEB 22985, 321.89 56* 71* 0. MAR 20020. 319.60 54* 71. 0. APR 18162, 318.27 71. 71, 0. MAY 26817. 324.95 243, 71. 0. JUN 13300, 314430 962* 1158* ol JUL 13300. 314.30 1695* 1664* 0. AUG 39300. 331.32 1628* 1174* 0, SEP 39300. 331.32 872. 841. ol YEAR 520. 453. 0# YR 1966 OCT 39300. 331.32 425, 394. 0. NOV 39300. 331.32 162. 131* 0. DEC 38118. 330.79 83. 71. 0. JAN 349684 329,38 51, 71* 0. FEB 32068* 327*82 50* 71. 0. MAR 28856. 326.10 50. 71. 0. APR 25808. 324,15 51. 71. 0. MAY 33972. 328.85 235. 71. 0. JUN 13300. 314.30 1150* 1467* 0. JUL 13300. 314.30 1858. 1827. 0. AUG 39300. 331* 32 1958. 1504. 0. SEP 39300* 331.32 1177, 1146o 0. YEAR 609. 577. 0. YR 1967 OCT 39300* 331.32 342. 311. 0. NOV 39300. 331.32 103o 72. ol DEC 37749* 330,63 77a 71, ol JAN 35583. 329*66 67. 71* ot FEB 32738* 328,18 51, 71* 0* MAR 29711. 326.56 53. 71. 0. APR 28091* 325.69 75* 71. 0. MAY 37485, 330.51 255, 71. 0* JUN 13300* 314,30 15074 1883. ot JUL 13300. 314.30 2116. 2085. 0. AUG 39300. 331.32 2221* 1767* ot SEP 39300. 331.32 1593. 1562. 0. YEAR 709* 678* 0* YR 1968 OCT 39300. 331.32 288. 257* 0. NOV 39300. 331.32 133. 102. 0. DEC 38056. 330.77 82. 71. 0. JAN 36198. 329.94 72. 71. 0. FEB 34075. 329.90 64. 71. 0. MAR 31540. 327.54 61. 71. 0. APR 29206. 326.29 63. 71. 0. MAY 39300. 331.32 356. 161. 0. JUN 13300. 314.30 961. 1367. 0. JUL 13300. 314.30 1775. 1744. 0. AUG 39300, 331.32 1450# 996. 0. SEP 39300. 331.32 476. 445. 0* YEAR 4864 455. 0. YR 1969 OCT 39300* 331.32 155. 124. 0. NOV 39300. 331.32 107. 76, ot DEC 37318. 330.44 70. 71. 04 JAN 33431. 328.56 39. 71. ot FEB 29531, 326.46 32. 71. 0. MAR 250284 324.16 42. 71. 0. APR 24446. 323.06 79. 71, 0. MAY 37959. 330.72 322. 71t 00 JUN 13300. 314.30 1252, 1636s 0, JUL 13300. 314.30 1564. 1533* 0. AUG 39300* 331.32 874. 420* 0. SEP 39300* 331.32 457. 426, 0. YEAR 419. 388. 0. YR 1970 OCT 39300. 331.32 707. 676. 0. NOV 39300. 331.32 174o 143. 0. DEC 39300* 331.32 119* 88, 04 JAN 39102. 331.23 99. 71. ol FEB 30423* 330.93 90. 71. 0. MAR 37363. 330*46 85* 71. 0. APR 35922. 329,81 78, 71. 0* MAY 39300. 331.32 218. 132* 00 JUN 13300. 314430 739. 1145* ol JUL 13300, 314.30 1303. 1272, 0. AUG 39300. 331.32 1241* 787. 0. SEP 39300. 331,32 588. 557. 0. YEAR 457. 426. 0. YR 1971 OCT 39300. 331.32 181. 150* 0. NOV 39300. 331.32 103* 729 04 DEC 37626. 330.57 75. 71, 0. JAN 34845. 329.32 .57. 71., 0. FEB 32056. 327482 52. 71* 0* MAR 28230. 325.76 40. 71. 0. APR 24289. 322.93 36. 71o 0* MAY 23045. 321.94 132. 71. 0. JUN 13300. 314.30 725. 858. 0. JUL 13300. 314.30 1772* 17414 0. AUG 39300. 331432 2002. 1548. 0. SEP 39300. 331.32 552. 521. 0. YEAR 478. 447. 0. YR 1972 OCT 39300. 331.32 191* 160. 0. NOV 3916B. 331.26 100. 71. 0. DEC 38416. 330.93 90. 71. 0. JAN 36127. 329.90 65. 71. 0. FEB 32615. 328.12 39. 71* 0. MAR 28543. 325.93 36. 71. 0. APR 25971. 324*28 591. 71. 0* MAY 28601. 325.96 145* 71. 0. JUN 13300.- 314.30 689. 915, 0. JUL 13300. 314.30 1747* 1716* 0. AUG 39300. 331.32 1589, 1135, 0. SEP 39300. 331.32 970. 939. 0, YEAR 481o 450. 0. YR 1973 OCT 393004 331,32 418. 387. 0. NOV 39300. 331.32 143. 112. ot DEC 39300. 331.32 123. 92. 0. JAN 37503. 330.52 73. 71o 0* FEB 34491o 329.13 48. 71. 0. MAR 30911, 327420 44. 71. ot APR 29053, 326.20 710 71. 0. MAY 32605. 328*11 160. 71. 0. JUN 13300. 314.30 662. 956* 0* JUL 13300. 314430 1290. 1259. 04 AUG 39300* 331.32 1227. 773* 0. SEP 393004 331.32 430. 399* 0. YEAR 394* 363. 0. YR 1974 OCT 39300. 331.32 267* 236. 0. NOV 38334. 330.89 86* 71. 0. DEC 35369. 329.56 54, 71. 0. JAN 31482, 327.51 394 71, 0. FEB 27248. 325.23 26. 71. 0. MAR 23422. 322,24 40. 71. 0. APR 21921. 321.04 77. 71* 0. MAY 32360, 327.98 272. 71. 0. JUN MOO. 314,30 921* 1210. 0. JUL 13300. 314.30 1472. 1441. 0. AUG 39300. 331*32 1489. 1035* ot SEP 39300. 331,32 1141. 1110. 0* YEAR 493. 463* 0. YR 1975 OCT 39300. 331,32 231. 200. 0. NOV 39300. 331.32 123. 92. 0. DEC 37995. 330*74 al. 71. 0. JAN 34661. 329.22 48. 71. 0. FEB 31482. 327.51 45. 71. 0. MAR 27964* 325.62 45. 71. 0. APR 26463* 324.67 77. 71. 0. MAY 39300. 331.32 313. 73. 0. JUN 13300. 314.30 746. 1152. 0. JUL 13300, 314.30 1652. 1621. 0. AUG 39300. 331.32 1307. 853. 0. SEP 39300. 331.32 756. 725. 0. YEAR 456. 425. 0* YR 1976 OCT 39300. 331.32 237. .206. 0. NOV 38632. 331.02 91. 71. 0. DEC 36343. 330.00 65. 71* 0. JAN 33501. 328*59 56. 71. 0. FEB 30767* 327.12 53, 71. 0. MAR 27310. 325.27 46. 71. 0. APR 25035. 323.53 64. 71. 0. MAY 29633. 326.52 177. 71. 06 JUN 13300. 314.30 889. 1133. 0. JUL 13300, 314.30 1615. 1584. 0. AUG 39300. 331.32 1386s 932. 0. SEP 3930of 331.32 900. 869. 0. YEAR 468* 437. 0, YR 1977 OCT 39300. 331.32 307* 276. 04 NOV 39300. 331.32 1900 1590 0* DEC 39300* 331.32 130. 99. 0. JAN 38794# 331.09 94. 71* 0. FEB 37504* 330,52 79, 71* 0. MAR 35031. 329.41 62. 71. 0. APR 33589. 328.64 78* 71. ol MAY 39300. 331.32 249. 125, 0. JUN 13300. 314,30 1333. 1739. 0. JUL 13300, 314.30 2120. 2089, 0. AUG 39300. 331.32 2424. 1970* 0. SEP 39300, 331.32 11000 1069. ot YEAR 686* 655* 0. YR, 1978 OCT 39300. 331.32 460* 429. 0. NOV 39300. 331.32 158. 127. 0. DEC 39300. 331.32 137. 106. 0. JAN 39300* 331,32 Ile* 87* ol FEB 39010. 331.19 97. 71, 0. MAR 37582* 330,55 79. 71* 0. APR 35783* 329./5 72. 71* 0. MAY 39300. 331,32 246* 158. ot JUN 13300. 314.30 816t 1222. 0. JUL 13Z,00, 314.30 1447. 1416, 0. AUG 39300. 331.32 1528. 1074* 0. SEP 39300* 331.32 971* 940. 0. YEAR 514, A83. 0. YR 1979 OCT 39300, 331.32 324. 293t ot NOV 39300, 331.32 116, 85. 00 DEC 37441* 330.49 72. 71, ol JAN 35153, 329*47 65* 71o 06 FEB 32863. 328o25 61. 71. 0. MAR 30820. 327.15 69. 71. 0. APR 31699. 327.63 117. 71. 0. MAY 39300* 331.32 366. 211, ol JUN 13300. 314*30 1082, 1488. ol JUL 13300. 314*30 2001* 1970. ol AUG 39300. 331*32 2103. 1649. 0. SEP 39300. 331,32 1098. 1067. ot YEAR 628* 597* ot YR 1980 OCT 39300. 331.32 251. 220. 0, NOV 39300. 331.32 114. 83. 0. DEC 37810. 330.66 78. 71. 0. JAN 33984. 328.85 40. 71. 0. FEB 29584. 326.49 23. 71. 0. MAR 25512. 323.91 36. 71. 0. APR 20798. 320.16 23. 71. 0. MAY 16664. 317.19 35. 71. 0. JUN 13300. 314,30 572* 598. 0. JUL 13300* 314.30 1146, 1115. 0. AUG 39300. 331.32 12004 746. 0. SEP 39300. 331*32 344, 313. 0. YEAR 325. 294. 0. YR 1981 OCT 39300. 33lo32 179. 148. 0. NOV 39168. 331.26 100, 71* 0. DEC 36694. 330.16 62, 71. 0* JAN 32622* 328.12 36. 71. 0. FEB 28111. 325*70 21. 71. 00 MAR 23609. 322.39 29* 71* 00 APR 20739. 320*11 54. 71. 0. MAY 26074. 324.36 189. 71. 0. JUN 13300. 31.4.30 673. 857. 0. JUL 13300. 314.30 1367, 1336* 0. AUG 39300. 331.32 1246. 792. 00 SEP 39300. 331.32 1054* 1023. 0. YEAR 420a 389. 0. YR 1982 OCT 39300. 331*32 589* 558* 0. NOV 39300. 331.32 129. 98. 0. DEC 39163. 331.26 100. 71. 0. JAN 37858. 330,68 81. 71* 0. FEB 36179. 329.93 72* 71. ol MAR 34690. 329.23 78. 71. 0. APR 33546. 328,62 83* 71. 0. MAY 39300. 331.32 352, 228. 0. JUN 13300* 314*30 9010 1307* 0* JUL 13300. 314*30 1631o 1600* 0. AUG 39300. 331.32 1469* 1015. 0. SEP 39300. 331.32 362* 331. 0. YEAR 492. 461. 0. YR 1983 OCT 39300. 331.32 141. 110. 0. NOV 38751. 331.08 93* 71. 0. DEC 36892. 330.25 72. 71. 0. JAN 33743. 328.72 51. 71. 0. FEB 30731. 327.11 48. 71. 0. MAR 26967. 325.07 41. 71. 04 APR 24156. 322.83 55. 71. 0. MAY 30476o 326.97 205. 71. 0. JUN 13300. 314-30 713. 971. 0. JUL 13300* 314.30 1643. 1612. 0. AUG 39300. 331.32 1786. 1332. 0. SEP 39300. 331.32 1503. 1472. 0. YEAR 533* 502. 0. YR 1984 OCT 39300. 331.32 372. 341. 0. NOV 39300. 331.32 142. ill. 0. DEC 39300. 331.32 104. 73. 0. JAN 37441. 330.49 72. 71. 0. FEB 34430. 329.09 48. 716 0. MAR 31034* 327*27 47. 71. 0* APR 27927. 325.60 50s 71* 0. MAY 29204. 326.28 123. 71. 0. JUN 13300. 314.30 862* 1098. 0. JUL 13300. 314.30 1596. 1565. 0# AUG 39300. 331.32 1612. 1158. 0. SEP 39300. 331.32 639. 608. 0. YEAR 47A. 4455t 04 YR 1985 OCT 39300. 331.32 289. 258, 0. NOV 39300. 331.32 109. 78* 0. DEC 36027. 329*86 49* 71. 0# JAN 32447. 328*03 44. 71. 0. FEB 28658. 325.99 34. 71* 0. MAR 25016. 323,51 43, 71. 0. APR 23515o 322.31 77* 71. 04 MAY 28420. 325.86 182. 71. 0# JUN 13300, 314*30 791, 1014. 0. JUL 13300* 314.30 1449. 1418. 0. AUG 39300* 331.32 1134, 680o 0. SEP 39300. 331*32 720. 689, 0. YEAR 413* 382. 0. YR 1986 OCT 39300, 331.32 337. 306* 0. NOV 39300, 331,32 145. 114* 04 DEC 37503. 330,52 73* 71. 0. JAN 35276. 329,52 66* 71. 0. FEB 32764* 328.20 57. 71, 0. MAR 30659. 327,07 68, 71t 0. APR 29158. 326.26 77* 71. 0# MAY 39300. 331*32 325* 129, 0* JUN 13300, 314.30 987o 1393o 0# JUL 13300o 314.30 1569* 1538, 0. AUG 39300. 331*32 1252* 798. 0. SEP 393006 331*32 617* 586. 0. YEAR 468* 437. 00 YR 1987 OCT 39300. 331.32 214. 183, 0@ NOV 38751. 331.08 93. 71. of DEC 36278, 329997 62. 71. 0. JAN 32574. 328.10 42, 71. 0# FEB 28230* 325*76 24, 71. 0. MAR 24342. 322*97 39, 71. 04 APR 20521. 319.96 38. 71. 00 MAY 18539. 318.54 70. 71. 0. JUN 13300o 314.30 784. 841. 04 JUL 13300, 314.30 1728* 16974 0. AUG 39300. 331.32 1409. 955* 0, SEP 39300* 331.32 760. 729. ot YEAR 442. 411, 01 YR 1988 OCT 39300. 331.32 245. 214. 00 NOV 39300. 331.32 132. 101. 0. DEC 39300. 331.32 114. 83. 0. JAN 38487. 330.96 89. 71. 0. FEB 36697. 330.16 70. 71. 0. MAR 34224. 328.98 62. 71. 0. APR 34032. 328.88 99. 71. 0. MAY 39300. 331.32 295. 179. os JUN 13300. 314.30 1159. 1565. 0. JUL 13300. 314.30 1907. 1876. 0. AUG 39300. 331.32 1646* 1192. 0. SEP 39300. 331,32 667# 636. 04 YEAR 545. 5i4. 0. YR 1989 OCT 39300. 331.32 181. 150. ot Nov 38334. 330.89 86. 71# 0. DEC 35984* 329.84 64, 71. of JAN 32158* 327.87 40, 71. 0. FEB 28036# 325#66 28. 71# 0. MAR 23902# 322.62 35. 71. 0. APR 20735. 320.11 49# 71. 0. MAY 24164# 322.83 158* 71. 0* JUN 13300# 314.30 678, 830# 0. JUL 13300# 314.30 16909 1659. ot AUG 39300o 331.32 1240# 786. 0. SEP 39300. 331,32 768# 737# 0. YEAR 422# 391. 0. YR 1990 OCT 39300# 331#32 242. 211. 0. NOV 39300# 331.32 153. 122. 0. DEC 38733, 331.07 93. 71. 0. JAN 36628, 330.13 68# 71. 00 FEB 34228. 328.98 59* 71. 00 MAR 31262. 327#39 54* 71. ot APR 28512. 325.91 56# 71. 00 MAY 36614. 330.12 234o 71* 0. JUN 13300o 314.30 782o 1143. 0. JUL 13300# 314.30 1434. 1403. 04 AUG 39300. 331.32 1214. 760# 0. SEP 39300. 331#32 506. 475. 0. YEAR 411* 380. ot YR 1991 OCT 39300. 331.32 163# 132* 0. NOV 37918, 330.70 79, 71# 0# DEC 34645. 329#21 49. 71. 0. JAN 30450. 326#95 34. 71. 0. FEB 25884. 324#21 20* 71. 0# MAR 21320# 320.56 28. 71# 0. APR 16665. 317,19 24# 71. 0. MAY' 13884. 314#88 57. 71, 0* JUN 13300. 314#30 605# 584* 0* JUL 13300. 314.30 1237* 1206# ol AUG 39300# 331.32 935* 481. 0. SEP 39300# 331#32 441# 410. 0. YEAR 309. 278o 0* YR 1992 OCT 39300. 331.32 512. 481. ot vouv ny6Qu. s,3 1 .32 194. 1,53. 0. DEC 39102. 331.23 199. 71. 0. JAN 37428. 330.48 75. 71. 0. FEB 35138. 329.46 61, 71. 0. MAR 32542. 328.08 60. 71. 0. APR 31755. 327.66 89. 71. ot MAY 39300. 331.32 253. 99. 0. JUN 13300. 314.30 1347* 1753. 0. JUL 13300o 314.30 1873# 1842. 0. AUG 39300. 331*32 2000. 1546. 0. SEP 39300. 331.32 723. 692. 0. YEAR 6i2t 58i. 0. YR 1993 OCT 39300. 331.32 135. 104. 0. NOV 38811. 331.10 94. 71* 0. DEC 36091. 329.89 58. 71. 0. JAN 32142. 327.86 38. 71. ol FEB 28297. 325.80 33. 71. 0. MAR 24410. 323.03 39. 71. ol APR 22076. 321*16 63* 71. 0. MAY 23538. 322.33 126. 71. 0. JUN 13300. 314.30 730. (371. 0. JUL 13300* 314.30 1595. 1564, 0# AUG 39300. 331.32 1363. 909. 0. SEP 39300. 331.32 612. 581* 0. YEAR 411. 380. 00 YR 1994 OCT 39300. 331.32 246# 215. 0. NOV 38513. 330.97 89* 71. 0. DEC 35609. 329.67 55* 71. 0. JAN 31537. 327.54 36. 71* 0. FEB 27304. 325.26 26. 71* ot MAR 23109* 321.99 34. 71# 0. APR 19227. 319*03 37. 71. 0. MAY 18045. 318.18 83. 71. 0. JUN 13300. 314.30 579. 628. ot JUL 13300. 314,30 1506. 1475. 0. AUG 39300. 331.32 837. 383. 0. SEP 39300. 331.32 569. 538* 0. YEAR 344. 313. 0* YR 1995 OCT 39300. 331.32 337. 306. 0. NOV 39300. 331.32 172, 141. 0. DEC 39300. 331.32 142. lit. 0. JAN 384254 330.93 88. 71. 0. FEB 36302. 329.98 64. 71. 0. MAR 33337, 328.51 54. 71. 0. APR 31241. 327.38 67. 71. 0. MAY 36269. 329.97 184. 71. 0. JUN 13300. 314.30 993. 1348. 0. JUL 13300. 314.30 1621. 1590. 0. AUG 39300. 331.32 1288. 834. 0. SEP 39300. 331.32 333. 302. 0. YEAR 449. 410. 0. YR 1996 OCT 39300. 331.32 242. 211. 0. NOV 39300. 331.32 113. 82. 0. DEC 39300. 331.32 117. 86. 0. JAN 38364. 330.90 87. 71. 0. FEB 36796. 330*20 74. 71. 0. MAR 34753. 329*27 69. 71. 0. APR 35037. 329.42 107. 714 0. MAY 39300. 331.32 415. 315. 0. JUN 13300# 314.30 1014. 1420. 0. JUL 13300. 314.30 1562. 1531* ol AUG 39300. 331.32 1490o 1036. Of SEP 39300, 331.32 772. 741* 0. YEAR 50?. 47e. 04 YR 1997 OCT 39300. 331*32 436. 405. 0. NOV 39300. 331.32 199. 168. 0. DEC 39300, 331.32 151* 120. Of JAN 39286, 331,31 102. 71* 0. FEB 37052. 330.32 62. 71. ol MAR 34825* 329.31 66* 71. 0. APR 36001* 329.85 122. 71. 0. MAY 39300* 331.32 420o 335. 0* JUN 13300. 314.30 1040, 1446. 0# JUL 13300. 314*30 1841. isloo 0. AUG 39300. 331,32 1664. 1210. 0. SEP 39300* 331*32 822# 791* 04 YEAR 582. 551. 09 YR 1998 OCT 39300. 331.32 216* 185. 0. NOV 38572. 331.00 900 71. ol DEC 35730. 329.73 56s 71, 04 JAN 31597, 327,57 35. 71. 0. FEB 27530. 325*38 29* 71* 0. MAR 23642. 322.41 39. 71* 0. APR 20118. 319.67 43. 71* 0. MAY 23363. 322.19 155. 71. 0. JUN 13300, 314.30 893. 1031t 0. JUL 13300, 314.30 1477s 1446o 0. AUG 39300* 331,32 1438* 984. 0. SEP 39300, 331432 784. 753, 0. YEAR 441. 410. 0. YR 1999 OCT 39300. 331.32 440. 409. 0. NOV 39300, 331.32 205, 174. 0. DEC 39300. 331*32 117# 86. 0. JAN 38364. 330.90 87. 71. 0. FEB 36741. 330418 73. 71. 0. MAR 35558. 329,65 83# 71. 0* APR 35307. 329.54 98. 71. 0. MAY 39300. 331.32 339. 243. 0. JUN 13300. 314.30 764. 1170. 0. JUL 13300. 314.30 1299. 1268. 0. AUG 39300. 331.32 1080. 626. 0. SEP 39300. 331.32 9004 869. 0. YEAR 460. 429* 0. YR 2000 OCT 39300. 331.32 203. 172. 0. NOV 38394. 330.92 87. 71. 0. DEC 35244. 329.51 51. 71. 0. JAN 31172. 327.34 36. 71. 0# FEB 27272. 325.25 32. 71. 0. MAR 23015. 321.91 33* 71, 0. APR 19729# 319.39 47* 71. 0. MAY 25987. 324.29 204. 71. 0. JUN 13300. 314.30 1675. 1857* 0. JUL 13300. 314,30 2121, 2090. 0. AUG 39300# 331.32 27434 2289. 04 SEP 39300. 331.32 1885., 1854. 0. YEAR 764. 733. 0. YR 2001 OCT 39300. 331.32 210. 179* 0. NOV 39300. 331.32 130* 99. 0. DEC 38497. 330.96 89. 71. 04 JAN 36444. 330.04 69. 71* 0. FEB 33488. 328.59 49. 71, 0* MAR 30399. 326.93 52. 71, 0. APR 29612, 326.50 89. 71, 06 MAY 39300. 331,32 349# 161. 00 JUN 133000 314.30 1226, 1632, 04 JUL 13300, 314.30 2084* 2053. ot AUG 393006 331.32 1621. 1167. 0. SEP 39300* 331.32 643, 612* 0. YEAR 555, 524. 01 YR 2002 OCT 39300. 331.32 239. 208. 0. NOV 37977* 330.73 80. 71. 0. DEC 35320. 329.54 59. 71* 0. JAN 31739. 327.65 44. 71, 0. FEB 28339. 325t82 41* 71, 0. MAR 25128. 323.60 50. 71. 0* APR 22556* 321,54 59. 71, 04 MAY 28875* 326*11 205. 71* 0* JUN 13300* 314.30 770, tool* 0. JUL 13300. 314,30 1405. 1374, 00 AUG 39300. 331*32 1392, 938. 0, SEP 39300. 331.32 531* 500. 0. YEAR 410. 379, 0. YR 2003 OCT 39300. 331.32 497. 466, 0. NOV 39300. 331*32 213# IB2. 04 DEC 39300, 331.32 140. 109. ot JAN 38548. 330.98 90. 71. 04 FEB 35981. 329.84 56. 71. 0. MAR 32585. 328.10 47* 71. 0. APR 31501. 327.52 84. 71* 0. MAY 39300. 331*32 262. 104, 0. JUN 13300. 314s30 628. 1034. 0# JUL 13300. 314.30 1479. 1448. 0. AUG 39300. 331.32 1168. 714o 0. SEP 39300. 331.32 920. 889, 0. YEAR 469. 438. 0. YR 2004 OCT 39300. 331.32 269. 238. 0. NOV 39300. 331*32 107. 76. 0. DEC 37134. 330.35 67. 71. 00 JAN 337384 328.72 47. 71, 0. FEB 29560. 326.48 27. 71. 0. MAR 25365s 323.79 34. 71. 0. APR 20711. 320t.09 24. 71. 0. MAY 15532. 316*38 18. 71. 0. JUN 13300. 314*30 847. 854. 0. JUL 13300. 314#30 1815. 17B4. 0. AUG 39300. 331.32 2008o 1554. 00 SEP 39300. 331.32 551. 520. 0. YEAR 487, 458* 0. YR 2005 OCT 39300, 331,32 301* 270* 0* NOV 39300o 331.32 129, 98* 0. DEC 39300. 331.32 103o 72* 0* JAN 38794, 331.09 94* 71. 0. FEB 37393. 330.47 77. 71. ot MAR 36088* 329.89 all 71. 0* APR 36134. 329#91 103. 719 0* MAY 39300, 331.32 306* 224. ot JUN 13300# 314.30 1006. 1412. 0, JUL 13300. 314*30 1761. 1730. 0* AUG 39300. 331*32 1820. 1366* 0, SEP 39300. 331,32 354, 323. ot YEAR 516* 485. 0. YR 2006 OCT 39300, 331.32 1800 149, 0. NOV 38275. 330.86 85. 71o 0. DEC 35617, 329.68 59. 71, 0* JAN 32037* 327.81 44* 71. 0. FEB 27915. 325*59 28. 71, 0. MAR 24150, 322*82 41* 71, 0* APR 21399* 320#62 56t 71. ol MAY 20463# 319,92 87* 71. 00 JUN 13300# 314.30 579. 668* Of JUL 13300. 314*30 1522* 1491* 06 AUG 39300- 331*32 1359# 905. 0# SEP 39300- 331.32 343. 312* 0. YEAR 369, 338. ol YR 2007 OCT 39300# 331.32 297. 266. 0. NOV 39300. 331.32 196. 165. ot DEC 39300. 331.32 103. 72, 0. JAN 37011. 330.30 65. 71. 0. FEB 34944. 329.37 65. 71. 0. MAR 31978- 327.78 54. 71. 0. APR 31072. 327.29 87# 71. 0. MAY 39300. 331432 326. 161* 0. JUN 13300. 314.30 692. 1098. 0. JUL 13300. 314.30 1383, 1352. of AUG 39300o 331.32 1038. 584. 0. SEP 39300- 331-32 351. 320. 0. YEAR 391. 360. 0. @YW 2008 OCT 39300. 331.32 120. 89. 0. NOV 3815o6. 330.81 83. 71. 0. DEC 35252. 329.51 55. 71. 0. JAN 31180. 327#35 36# 71# 0. FEB 26502# 324.70 18. 71# 0. MAR 22430. 321.44 36. 714 0. APR 19204. 319.01 48# 71# 0, MAY 26999. 325.10 229# 71. 04 JUN 13300t 314.30 1035# 1234# 0. JUL 13300# 314#30 1786. 1755# 0* AUG 39300* 331#32 1892# 1438# 0. SEP 39300# 331#32 868. 837* 0# YEAR 521# 490# 04 YR 2009 OCT 39300. 331#32 447t 4164 0. NOV 39300. 331#32 223# 192, 04 DEC 39300# 331#32 131# loot 0. JAN 387334 331*07 93* 71. 0# FEB 36887* 330.24 69* 71. 0. MAR 34476. 329,12 63# 71. 0. APR 33331. 328.50 83. 71. 0. MAY 39300# 331.32 264# 136. 0. JUN 13300* 314.30 B20* 1226* 04 JUL 13300# 314.30 1691# 1660. 0# AUG 39300# 331.32 1320, 866. 0. SEP 39300* 331.32 822# 791. 0* YEAR 506# 475. 0. YR 2010 OCT 39300# 331.32 167, 136. 04 NOV 37204# 330#38 67# 71. 0. DEC 33993* 328.86 50* 71. 0# JAN 30105, 326#77 39, 71. 06 FEB 25927* 324.24 27* 71, of MAR 21671. 320.84 334 71. 00 APR 19039* 318.89 58* 71. 0. MAY 30954. 327.23 296# 71. 0. JUN 13300. 314#30 912# 1178. 0. JUL 13300# 314.30 1512. 1481# 0. AUG 39300# 331.32 1794, 1340. 0. SEP 39300# 331.32 970# 939. 04 YEAR 497. 467* 00 HECO-3 computer printout for the 108 cfs (70 mgd) firm-yield reservoir RESERVOIR SYSTEM ANALY,.)IS 723--X6-L2030 I JULY 1974 EAGLE RIVER WATER SUPPI..Y STUDY RESERVOIR OPERATION ANALYSIS GATES OPEN JUN I-AUG 1 NYRS IYR NL ICONS IDVSP IPWPR IDVPR IFLOW JUPOI 46 1965 4 0 0 0 0 1 0 CLOCL CFLOD IUNIT METRC CNSTI CNSTO CCFS OUNIT CACFT VONIT I PR NT IPRL IPWKW IUPDT IDOST 1.00 1.00 0 0 1.000 1.000 10000 CFS 1.000 ACFT -1 . 0 0 0 0 IRG(I)= 0 IRG(2)= 0 IRG(3)= 0 IRG(4)= 0 IRG(5)= 0 IRG(6)= 0 IRG(7)= 0 IRG(B)= 0 IRG(9)= 0 IRG(10)= I NPER= 12 IPERA= 10 PERIOD OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP NDAYS 31 30 31 31 28 31 30 31 30 31 31 30 EVP 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0*00 0.00 0.00 CONTROL POINT SEQUENCE CP NO I LOWER DAMSITE MDNST MDIV MRES MPWR NTSRV IPRN NFLW QDV UMN QM2 QMxx 2 1 1 0 0 0 0 31. 100. 0.1000000. RESERVOIR DATA% INITIAL STOR 56700. CEVAP = 1.000 QLKG 0. ISRCH 0 S T 0 R A 6 E S OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP LEVEL 4 56700. 56700. 56700. f16 700. 56700. 56700. 56700. 56700. 15700* 15700. 56700* 56700. LEVEL 3 56700. 56700. 56700s 56700. 56700. 56700. 56700. 56700. 15700. 15700. 56700. 567004 LEVEL 2 15700. 15700. 15700. 15700. 15700. 15700. 15700 * 15700. 157004 15700. 15700. 15700. LEVEL 1 15700. 15700. 15700. 15700. 15700. 15700. 15700. 15700. 15700. 15700. 15700. 157006 STOR 1000. 2000. 4000. 8000. 12000. 15000. 21000. 27000. 35000. 60000. AREA 150.0 237.0 350. 0 675.0 910.0 1030.0 1320.0 1690.0 2050.0 2650.0 LICAP 10000. 20000. 30000. 40000. 50000. 60000. 80000. 100000. 150000. 200000 ELEV 287.00 292.80 300.00 308.00 313*00 316.00 320*30 325.10 329.40 340.0; CP NO 2 DOWNSTREAM MDNST MDIV MRES MPWR NTSRV IPRN NFLW QDV OMN QM2 omxx --I 1 0 0 0 0 1 -1. 0. 0.1000000. MO AND RTIO= 1 0.000 DIVERSION=-1.000 TIMES DIVERSION AT I 1 OFLOW REQUIREMENTS AT 1 MULTIPLIED BY 1.041 IANNUAL INPUT DATA FOR 1965 **INFLOWS STA 1 324. 128. 90. 67. 56. 54. 71. 243. 962. 1695. 1628# 872, ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTr AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1966 **INFLOWS - STA 1 425. 162. 83* 51. 50. 50* 51. 235* 11500 1858, 1958. 1177, ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFT? AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1967 **INFLOWS STA 1 342. 103. 77. 67o 51. 53o 75, 255o 1507. 2116. 2221* 1593. ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTY AND POWER IN THOUSAND KWH 1ANNUAL INPUT DATA FOR 1968 **INFLOWS STA 1 288# 133, 82, 72. 64. 61. 63. 356. 961. 1775. 1450, 476, ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTY AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1969 **INFLOWS STA 1 155. 107. 70. 39. 32# 42* 79t 322t 1252* 1564. 874. 457* ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTF AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1970 **INFLOWS STA 1 707. 174. 119. 99. 90, 85. 78. 218. 739* 1303. 1241. 588o ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTP AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1971 **INFLOWS STA 1 1814 103. 75. 57t 52o 40* 36* 82, 725. 1772* 2002. 552o ALL FLOWS IN CFSt STORAGES AND EVAP IN ACFTP AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1972 **INFLOWS STA 1 191. 100. 90. 65, 39o 36* 59. 145. 689, 1747* 1589. 970. ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTY AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1973 **INFLOWS STA 1 418. 143. 123. 73. 48. 44. 71* 160. 662. 1290. 1227* 430, ALL FLOWS IN CFSY STORAGES AND EVAP IN ACFTv AND POWER IN THOUSAND KWH 1ANNUAL INPUT DATA FOR 1974 **INFLOWS STA 1 267, 86. 54* 39. 26. 40. 77. 272, 921. 1472. 1489o 1141o ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTt AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1975 **INFLOWS STA 1 231o 123. al. 48* 45. 4.) 77* 313. 746. 1652. 1307o 756t ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTP AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1976 **INFLOWS STA 1 137. 91. 65. 560 53# 46. 64t 177. 989. 1615* 1386. 900, ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTP AND POWER IN THOUSAND KWH 1ANNUAL INPUT DATA FOR 1977 **INFLOWS STA 1 307, 190. 130. 94. 79. 62. 78. 249# 1333. 2120, 2424. 1100, ALL FLOWS IN CFSY STORAGES AND EVAP IN ACFTt AND POWER IN THOUSAND KWH 1ANNUAL INPUT DATA FOR 1978 **INFLOWS STA 1 460. 158* 137o Ile* 97* 79. 72# 246, 816o 1447* 1528* 971, ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFI*p AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1979 **INFLOWS STA 1 324* 116, 72. 65* 61. 69o 117. 366, 1082o 2001. 2103o 1098. ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTP AND POWER IN THOUSAND KWH 1ANNUAL INPUT DATA FOR 1980 **INFLOWS STA 1 251. 114. 78. 40, 23. 36. 23, 3 572. 1146. 1200. 344. ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTi AND POWER IN THOUSAND KWH 1ANNUAL INPUT DATA FOR 1981 **INFLOWS STA 1 179. 100. 62* 36. 21* 29. 54. 189* 673, 1367. 12469 1054o ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTP AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1982 **INFLOWS STA 1 589. 129* loo. al. 72. 78. 83* 352. 901t 1631. 1469, 362* ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTY AND POWER IN THOUSAND KWH 1ANNUAL INPUT DATA FOR 1983 **INFLOWS STA 1 141, 93. 72. 51* 48. 41. 55. 205* 713t 1643. 1786* 1503. ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTY AND POWER IN THOUSAND KWH 1ANNUAL INPUT DATA FOk 1984 **INFLOWS STA 1 372. 142, 104* 72o 48- 47* 50- 123* 862o 1596, 1612o 639, ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTY AND POWER IN THOUSAND KWH 1ANNUAL INPUT DATA FOR 1985 **INFLOWS STA 1 299. 109. 49. 44. 34., 43. 77, 182. 791. 1449* 1134* 720. ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTY AND POWER IN THOUSAND KWH 1ANNUAL INPUT DATA FOR 1986 **INFLOWS STA 2 337. 145. 73. 66. 57. 68. 77. 325. 987. 1569. 1252. 6170 ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTP AND POWER IN THOUSAND KWH 1ANNUAL INPUT DATA FOR 1987 **INFLOWS -STA 1 214. 93* 62. 42. 24. 39. 38# 70. 784. 1728. 1409. 760. ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTs, AND POWER IN THOUSAND KWH 1ANNUAL INPUT DATA FOR 1988 **INFLOWS STA 1 245* 132. 114. 99* 70, 62. 99, 29S, 1159. 1907. 1646. 667 ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTP AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1989 **INFLOWS STA 1 181, 96. 64. 40. 28. 35. 49. 158. 678# 1690. 1240o 768o ALL FLOWS IN CFSY STORAGES AND EVAP IN ACFTv AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1990 **INFLOWS STA 1 242. 153. 93# 68* 59. 54. 56. 234. 792. 1434o 1214. 506t ALL FLOWS IN CFSt STORAGES AND EVAP IN ACFTr AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1991 **INFLOWS STA 1 163. 79# 49, 34, 20. 28. 24, 57. 605o 1237. 935. 441* ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTP AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1992 **INFLOWS STA 1 512. 194. 99. 75* 61. 60. 890 253. 1347# 18734 2000, 723. ALL FLOWS IN CFSP STORAGES*AND EVAP IN ACFTv AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1993 **INFLOWS STA 1 135. 94. 58. 38. 33. 39. 63. 126* 730. 1595o 1363. 612o ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTF AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1994 **INFLOWS STA 1 246. 89. 55. 36* 26. 34. 37. 63. 579. 1506, 837. 569. ALL FLOWS IN CFS? STORAGES AND EVAP IN ACFTP AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1995 **INFLOWS STA 1 337. 172. 142. 88. 64s 54. 67. 184s 993. 1621. 1288. 333. ALL FLOWS IN CFSr STORAGES AND EVAP IN ACFTP AND POWER IN THOUSAND KWH 1ANNUAL INPUT DATA FOR 1996 **INFLOWS STA 1 242. 113. 117. 87o 74. 69. 107, 415. 1014. 1562, 1490o 772 ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTY AND POWER IN THOUSAND KWH 1ANNUAL INPUT DATA FOR 1997 **INFLOWS STA 1 436. 199. 151. 102* 62. 66. 122. 420s 1040. 1841. 1664* 822 ALL FLOWS IN CFS, STORAGES AND EVAP IN ACFTt AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1998 **INFLOWS STA 1 216. 90. 56* 35* 29. 39* 43. 155. 893, 1477. 1438o 784* ALL FLOWS IN CFS, STORAGES AND EVAP IN ACFTP AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 1999 **INFLOWS STA 1 440. 205. 117* 87. 73. 93. 98* 339. 764. 1299o 1080* 900, ALL FLOWS IN CFS, STORAGES AND EVAP IN ACFTP AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 2000 **INFLOWS STA 1 203. 87. 51. 36, 32. 33. 4;, 204. 1675, 2121. 2743. 1885. ALL FLOWS IN CFSY STORAGES AND EVAP IN ACFTF AND POWER IN THOUSAND KWH 1ANNUAL INPUT DATA FOR 2001 **INFLOWS STA 1 210. 130* 89. 69. 49. 52* 99, 349. 1226o 2084o 1621, 643. ALL FLOWS IN CFSp STORAGES AND EVAP IN ACFTY AND POWkR IN THOUSAND KWH IANNUAL INPUT DATA FOR 2002 **INFLOWS STA 1 239. 90. 59o 44, @1. 504 59. 205, 770, 1405. 1392* 531, ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTv AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 2003 **INFLOWS STA 1 497. 213. 140. 90. 56* 47. 84. 262. 628. 1479. 1168. 920. ALL FLOWS IN CFSY STORAGES AND EVAP IN ACFTP AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 2004 **INFLOWS STA 1 269, 107. 67. 47. 27, 34* 24. 18. 847, 1815. 2008. 551, ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTP AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 2005 **INFLOWS STA 1 30.1, 129. 103. 94* 77. 81. 103. 306o 1006. 1761t 1820o 354. ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTv AND POWER IN THOUSAND KWH IANNUAL INP-'T DATA FOR 2006 **INFLOWS STA I :k8o. 85o 59, 44. 28* 41# 56, 87. 579. 1522o 1359# 343o ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTP AND POWER IN THOUSAND KWH 1ANNUAL INPUT DATA FOR 2007 **INFLOWS STA 1 297# 196. 103. 65. 65. 54* 87. 326. 692. 1383* 1038. 351o ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTY AND POWER IN THOUSAND KWH 1ANNUAL INPUT DATA FOR 2008 **INFLOWS STA 1 120. 83. 55. 36. 18. 36. 48. 229. 1035. 1786. 1892. 868# ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTi AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 2009 **INFLOWS STA 1 447. 223. 131. 93. 69. 63. 83. 264. 820. 1691. 1320. 822o ALL FLOWS IN CFSP STORAGES ANY) EVAP IN ACFTP AND POWER IN THOUSAND KWH IANNUAL INPUT DATA FOR 2010 **INFLOWS STA 1 167. 67. 50. 39. 27. 33. 58* 296. 912. 1512* 1794* 970, ALL FLOWS IN CFSP STORAGES AND EVAP IN ACFTv AND POWER IN THOUSAND KWH AVERAGES FOR PERIOD OF OPERATION 1965 - 2010 1 LOWER DAMSITE LOC FLW 486. UNREG 496. INFLOW 486. REO DIV 30*9 DIVERSN 30.9 SHORTGE 040 EVAPO 0. CSV REL 71* RIV FLW 454o DES FLW 71t SHORTGE ol 2 DOWNSTREAM LOC FLW 0. UNREG 486* INFLOW 454. REO DIV -30.9 DIVERSN -30.9 SHORTGE 0.0 RIV FLW iss, DES FLW ol SHORTGE 0* DIVERSION SHORTAGE INDEX 1 0.000 2 -1,000 DES FLOW SHORTAGE INDEX 1 0.000 2 -1.000 MIN FLOW SHORTAGE INDEX 1 -1.000 2 -1*000 DIVRSION SHORTAGES DES FLOW SHORTAGES MIN FLOW SHORTAGES SYS PWR SHORTAGES AT SITE PWR SHRTGS STA NO MAX NO MAX NO MAX NO MAX NO MAX 1 0 0# 0 0* 0 0. 0 ol 0 0. 2 - - 0 0. 0 0* 0 0. 0 ot STORAGE FREQUENCY PER 46 YEARS AT LOCATION I CONS POOL OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP 99-100 PCT 45 31 16 3 0 0 0 Is 46 46 46 46 95- 99 PCT 0 11 5 a 2 0 0 0 0 0 0 0 90- 95 PCT 0 3 9 5 6 2 0 2 0 0* 0 0 80- 90 PCT 0 0 14 10 9 8 6 2 0 0 0 0 70- 80 PCT 0 0 1 14 a 5 7 3 0 0 0 0 60- 70 PCT 0 0 0 5 6 7 6 4 0 0 0 0 40- 60 PCT I I 1 1 14 15 10 a 0 0 0 0 20- 40 PCT 0 0 0 0 1 9 15 5 0 0 0 0 1- 20 PCT 0 0 0 0 0 0 2 4 0 0 0 0 0- 1 PCT 0 0 0 0 0 0 0 0 0 0 0 0 EAGLE RIVER WATER SUPPLY STUDY RESERVOIR OPERATION ANALYSIS GATES OPEN JUN I-AUG 1 RESERVOIR DATA +++++4 ........ 4...... 4-4-4-+4 ....................... + CP NO I LOWER DAMSITE + 4................... ++4 ................... MONTH STORAGE ELEV INFLOW OUTFLOW EVAP (JiF N PW R /23X AC-FT F T CFSCFS AC-F'f 1000 KWH YR 1965 OCT 56700, 338.60 324. 293. 0. NOV 56284. 338.42 128. 104. 0. DEC 53517. 337.25 90. 104. 0. JAN 49336. 335.48 67. 104. 0. FEB 44949. 333.62 56. 104. 0. MAR 39968. 331.51 54. 104. 0. APR 36160. 329.89 71. 104. 0. MAY 42801. 332.71 243, 104. JUN 15700. 316.50 962. 0. JUL 15700, 316#50 1695. 1664. 0. AUG 56700. 338.60 1628. 930. 0. SEP 56700. 330.60 872. 841. 0. YEAR 520. 489. 0. YR 1966 OCT 56700. 336.60 425. 394. 0. NOV 56700, 338.60 162. 131. 0. DEC 53503. 337.25 83. 104. 0. JAN 48338. 335.06 51. 104. 0. FEB 43618. 333.05 50. 104. 0. MAR 38391. 330.84 50. 104. 0. APR 33393. 328.54 51. 104. 0. MAY 39542* 331.33 23t@. 104. 0. JUN 15700. 316.50 1150. 1520. 0. JUL 15700. 316.50 1858. 1827. 0. AUG 56700. 33B.60 1958. 1260. 0. SEP 56700. 338.60 1177. 0. YEAR 608. 577. 0. YR 1967 OCT 56700. 338-60 342. 311. 0. NOV 54796. 337-79 103. 104. 0. DEC 51230. 336.28 77. 104. 0. JAN 47049. 334.51 67. 104. 0. FEB 42384. 332.53 .51. 104. MAR 3 7,'S 4 2. 330.39 53. 1.04. 0. APR 33772, 328-74 75. 104. 0. MAY 41151. 332. 01 255. 104. 0. JUN 15700. 316.50 1507. 1904. 0. JUL 15700. 316.50 2116. 2005. 0. AUG 56700. 338.60 2221. 1523. 0. SEP 56700. 338.60 1593. 1562. 0. YEAR 7090 678. 0. YK 1969 OCT 56-/00. 338. "50 288. 257. 0. NOV 5L581. 338.55 133. 104. 0. DEC 53323. 337.17 82. 104. 0. JAN 49449. 335.53 72. 1.04. 0. FEB 45506. 333.85 64. 104. 0. MAR 40956. 331.93 61. 104. 0. APR 36672. 330.11 63. 1044 0. MAY 50261. 335.87 356. 104. 0. JUN 15700. 316.50 961. 15114 JUL 15700. 316.50 1775. 1.7444 0. AUG 56700. 338.60 1450. 752. 0. SEP 56700. 338#60 476. 445. 0* YEAR, 486. 455. 0. YR 1969 OCT 56700. 338.60 155. 124. 0. NOV 55034. 337.89 107. 104. 0. DEC 51038. 336.20 70. 104. 0. JAN 45135. 3,A3.70 39. 104. 0. FEB 39435. 331.27 32. 104. 0. MAR 33697. 328.70 42. 104. 0. APR 30365. 326.91 79. 104. 0. MAY 41863. 332.31 322. 1.04. 0. JUN 15700. 316.50 1252. 1661. 0. JUL 15700. 316.50 1564. 1533. 04 AUG 56700. 338.60 874. 176. 0. SEP 56700. 330.60 457. 426. 0. YEAR 419. 388. 0. YR 1970 OCT 56700. 338.60 707. 676. 04 NOV 56700. 338.60 174. 143. 0. DEC 338.18 1194 104. 0. JAN 53503. 337.25 994 104. 0. FEB 51004. 336.19 90. 104. 0. MAR 47930. 334*88 85. 104. 0. APR 44538. 333.44 78. 104. 0. MAY 49642* 335.61. 218. 104. 0. JUN 15700. 31.6.50 739. 1279. 0. JUL 15700. 3146.50 1303. 1272. 0. AUG 56700. 338.60 1241, 543. 0. SEP 56700. 338.60 588. 55-7. ot YEAR 457. 426. 0. YR 1971 OCT 56700. 338.60 181. 150. 0. NOV 54796. 337.79 103. 104. 0. DEC 51107. 336.23 75. 104. 0. JAN 46311. 334.20 57. 104. 0. FEB 41702. 332.24 52. 1,04. 0. MAR 35661. 32?.76 40. 104. 0. APR 29970. 326.70 36. 104. 0. MAY 26711. 324.87 82. 104. 0. JUN 15700. 316.50 725. 879. 0. JUL 15700. 316.50 1772. 1741. AUG 56700. 338.60 2 0 021 . 1,304. 0. SEP 56700. 339.60 552. 521. 0. YEAR 478. 447. 0. YR 1972 OCT 56700. 338.60 191. 160. 0. IVV, IV,*. %). DEC 51051. 336.54 90. 104. 0. 'JAN 47547. 334.72 65. 104. 0. FEE, 42215. 332.46 39. 104. 0. MAR 36128. 329.B8 36. 104. 0. APR 31606. 327.58 59. 104. 0. MAY 32221. 327.91 145. 104. 0. JUN 15700. 316.50 689. 936. 0. JUL 15700. 316.50 1.74/. 1716. 0. AUG 56700. 3,@8.60 1589. 891. 0. SEP 56;100. 338.60 970. 939. 0. YEAR 481. 450. 0. YR 1973 OCT 56700. 338.60 418. 387. 0. NOV 56700. 338.60 143. 11.2. 0. DEC 55962. 338.21? 123. 104. 0. JAN 521.50. 336.67 73. 104. 0. FEB 47319. 334.62 48, 104. 0. MAR 41724. 332.25 44, 104. 0. APR 37916. 330.64 71. 104. MAY 39453. 331.29 160. 1.04. 0. JUN 15700. 316.50 662. 1030. 0. JUL 15?00. 316.50 1290. 1259. 0. AUG 56-/00. 338.60 1227. 529. 0. SEP 56700. 338.60 430. 399. 0. YEAR 394, 363. 0. YR 1974 OCT 56700. 33B.60 267* 236. 0. NOV 53784. 337.36 86. 104. 0# DEC 48804. 335.25 54. 104. 0. .JAN 42902. 332.75 39. 104. 0. FEB 36848. 330.18 26* 104. 0. MAR 31007. 327.25 40. 104. 0. APR 27556. 325.40 77. 104. 04 MAY 35980. 329.82 272. 104. 0. JUN 15700. 316.50 921. 1231. 0. JUL 15700. 316.50 1472. 1441. 0. AUG 56700. 338.60 1409. 791. 0. SEP 56700. 338.60 1141. 1110. 0. YEAR 493. 463. 0. YR 1975 OCT 56700. 330.60 231. 200s 0. NOV 55986. 338.30 123. 104# 0. DEC 52666. 336.89 81. 104. 0. JAN 47317. 334.62 48. 104# 0. FEB 42319. 332.50 45. 104. 0. MAR 36785. 330.16 45. 104. 0. APR 33334. 328.50 77. 104# 0. MAY 44279, 333.33 313. 104. 0. JUN 15700. 316.50 746, 1195. 0. JUL 15700. 316.50 1652. 1621. 0. AUG 56700, 338.60 1307. 609. 0. SEP 56700. 338.60 756, 725. 0. YEAR 456. 425. 0. YK 1976 OCT 56700. 338.60 237. 206. 0. NOV 54082. 337.49 91. 104. 0. DEC 49778. 33S.67 65. 104. 0. JAN 44921. 333.61 56. 104. 0. FEB 40367. 331.68 53. 104. 0. MAR 34895. 329.34 46. 104. 0. APR 30670. 327.07 64. 104, 0. MAY 33253* 328.46 177. 104. 0. JUN 15700. 316.50 889. 1153. 0. JUL 15700. 316.50 1615. 1584. 0. AUG 56700. 338.60 1386. 688* 0. SEP 56700. 338.60 900. 869. 0. YEAR 468. 437* 0. YR 1977 OCT 56700. 338.60 307. 276. 0. NOV 56700. 338.60 190. 159. 0. DEC 56393. 338.47 130. 104. 0. JAN 53872. 337*40 94. 104. 0. FEB 50762. 336.08 79. 104. 0. MAR 46274. 334.18 62. 104. 0. APR 42882. 332.74 78. 104. 0. MAY 49892. 335.71 249. 104. 0* JUN 15700. 316.50 1333. 1877* 0. JUL 15700. 316.50 2120. 2089. 0. AUG 56700. 33B.60 2424. 1726* 0. SEP 56700. 338.60 1100. 1069. 0. YEAR 686. 655. 0. Yk 1978 OCT 56700. 338.60 460. 429. 0. NOV 56700. 338.60 158. 127. 0. DEC 56700. 338.60 137. 106. 0. JAN 55655. 338.16 lie. 104. 0. FEB 53545. 337.26 97. 104. 0. MAR 50102. 335.80 79. 104. 0. APR 46353. 334.21 72. 104. 0. MAY 53178. 337.11 246. 104. 0. JUN 15700. 316.50 816. 1415. 0. JUL 157004 316.50 1447. 1416. 0. AUG 56700. 338.60 1528. 830. 0. SEP 56700. 338.60 971. 940. 0. YEAR 514. 483. 0. YR 1979 OCT 56700* 338-60 324. 293. 0. NOV 55570. 338.12 116. 104. 0. DEC 51696. 336.48 72. 104. 0. JAN 473924 334.65 65. 104. 0. FEB 43283. 332.91 61. 104. 0. MAR 39225. 331.19 69. 104. 0. APR 38154. 330.74 117. 104. 0* MAY 52357. 336.76 366. 104. 0. JUN 15700. 316.50 1082. 1667. 0. JUL 15700. 316.50 2001. 1970. 0. AUG 56700. 338-60 2103. 1405. 0. SEP 56700, 338.60 1098. 1067, 0. YEAR 628. 597. 0. Yk 1980 OCT 56700. 338-60 251. 220. 0. Nuv bb4@)I. 636. 0 114. 104. 0. DEC 51946. 336.59 78. 104. 0. JAN 46105. 334.11 40. 104. 0. FEE, 39885. 331.47 104. 0. MAR 33798. 328.75 36. 104. 0. APR 27134. 325.17 23. 104. 0. MAY 20985. 320.29 35. 104. 0. JUN 15700. 316.50 572. 630. 0. JUL 15700. 316.50 1146. 1115. 0. AUG 56700. 330.60 1200. 502. 0. SEP 56700. 338.60 344. 313. 0. 325i 2944 YR 1981 OCT 56700. 338.60 179. 148. 0. NOV 54618. 337.72 100. 104. 0. DEC 50129. 335.81 62. 104. 0. JAN 44042. 333.23 36. 104. 0. FEB 37711. 330.55 21. 104. 0. MAR 31194. 327.35 29. 104. 0. APR 26374. 324.60 54. 104. 0. MAY 29694. 326.55 189. 104. 0. JUN 15700. 316.50 673. 877. 0. JUL 157004 316.50 1367. 1336. 0. AUG 56700. 338.60 1246. 548. 0. SEP 56700. 338.60 1054. 1023. 0. YEAR 420. 389. 0. YR 19B2 OCT 56700. 338.60 589. 558. 0. NOV 56343. 338.45 129. 104. 0. DEC 54191. 337.54 100. 104. 0. JAN 50871. 336.13 al. 104. 0. FEB 47372. 334.65 72. 104. 0. MAR 43868. 333.1.6 78. 104. 0. APR 40774. 331.85 03. 104. 0. MAY 54117. 337.51 352. 104. 0. JUN 15700. 316.50 901. 1516. 0. JUL 15700. 316.50 1631. 1600. 0. AUG 56700. 338-60 1469. 771. SEP 56700. 338.60 362. 331. 0. YEAR 492. 461. 0. YR 1983 OCT 56700. 338.60 141, 110, 0. NOV 54201. 337.54 93. 104. 0. DEC 50327. 335.90 72. 104. 0. JAN 45163. 333.71 51. 104. 0. FEB 40331. 331.66 48. 104. 0. MAR 34552. 329.16 41. 104. 0. APR 29791. 326.60 55. 104. 0. MAY 34096. 328.91 205. 104. 0. JUN 15700. 316.50 713. 991. 0. JUL 15700. 316.50 1643. 1612. 0. AUG 56700. 338.60 1786. 1088. 0. SEP 56700. 338.60 1503. 1472. 0. YEAR 533. 502. 0. Yk 19B4 OCT 56700. 338.60 372. 341. 0. NOV 56700. 338.60 142. Ill. 0. DEC 54794. 337.79 104. 104. 0. JAN 50921. 336.15 72. 104. 0. FEB 46089. 334.10 48. 104. 0. MAR 40678. 331.81 47. 104. 0. APR 3t;621. 329.66 50. 104. 0. MAY 34883. 329.34 123. 104. 0. JUN 15700. 316.50 B62, 1153. 0. JUL 15700. 316.50 1596. 1565. 0. AUG 56700* 338.60 1612. 914. 0. SEP 56700. 338.60 639* 608. 0. YEAR 445, 0. YR 1985 OCT 56700. 338.60 289. 258. 0. NOV 55153. 337.94 109. 104. 0. DEC 49865* 335.70 49* 104. 0. JAN 44270, 333.33 44. 104. 0. FEB 38661. 330.95 34. 104. 0. MAR 33004. 328.33 43. 104. 0. APR 29553. 326.47 77. 104. 0. MAY 32443. 328.03 182. 104. 0. JUN 15700. 316.50 791. 1041. 0. JUL 15700. 316.50 1449. 1418. 0. AUG 56700. 338.60 1134* 436. 0. SEP 56700. 338.60 720. 689. os YEAR 413. 382. 0. YR 1996 OCT 56700* 338.60 337. 306. 0. NOV 56700. 338.60 145. 114. 0. DEC 52888. 336*98 73. 104. 0. JAN 48646. 335.19 66. 104. 0. FEB 44314. 333.35 57. 104. 0. MAR 40194. 331.60 68. 104. 0. APR 36743. 330.14 77. 104. 0. MAY 48426. 335.09 325. 104* 0. 'JUN 15700. 316.50 987. 1506. 0. JUL 15700. 316.50 1569. 1538. 0. AUG 56700. 338.60 1252. 554. 0. SEP 56700. 338.60 617. 586. 0. YEAR 468. 437. 0. YR 1987 OCT 56700. 339.60 214. 183, 0. NOV 54201. 337.54 93. 104. 0. DEC 49713. 335.64 62. 104. 0. JAN 43994. 333.21 42. 104. 0. FEB 37830. 330.60 24. 104. 0. MAR 31927. 327.75 39. 104. 0. APR 26156. 324.42 38. 104. 0. MAY 22159. 321.23 70. 104. 0. JUN 15700. 316.50 784. 862. 0. JUL 15700. 316.50 1728. 1697. 0. AUG 56700. 338.60 1409. 711. 0. SEP 56700. 338.60 760. 729, 0. YEAR 442. 411. 0. YR 19BO OCT 56700. 338.60 245. 214. 0. NOV 56522. 338.53 132. 104. 0. DEC 55231. 337.98 114. 104. 0. JAN 52402. 336.78 89. 104. 0. FEB 48793. 335.25 70. 104. 0. MAR 44304. 333.34 62. 104. 0. APR 42162. 332.44 99. 104. 0. MAY 52000. 336.61 295. 104. 0. JUN 15700. 316.50 1159. 1738. 0. JUL 15700. 316.50 1907. 1876. 0. AUG 56700. 338.60 1646. 948. 0. SEP 56700. 338.60 667. 636. 0. YEAR 545. 514. 0. YR 1989 OCT 56700. 338.60 181. 150. 0. NOV 53784. 337.36 86. 104. 0. DEC 49419. 335#51 64. 104. 0. JAN 43578. 333.04 40. 104. 0. FEB 37636. 330.52 28. 104. 0. MAR 31487. 327.51 35. 104. 0. APR 26370. 324.60 49. 104. 0. MAY 27784. 325.52 158. 104. 0. JUN 15700. 316.50 678. 850* 0. JUL 15700. 316.50 1690. 1659. 0. AUG 56700. 338.60 i240. 542. 0. SEP 56700. 338.60 768. 737. 0* YEAR 422. 391. 0. Yk 1990 OCT 56700. 338*60 242. 211. 0. NOV 56700. 338.60 153. 122. 0. DEC 54118. 337.51 93. 104. 0. JAN 49998. 335.76 68. 104. 0. FEB 45778. 333.97 59. 104. 0. MAR 40797. 331.86 54. 104. 0. APR 36097. 329.86 56. 104. 0. MAY 42184. 332.45 234. 104. 0. JUN 15700. 316.50 782. 1196. 0. JUL 15700. 316.50 1434. 1403. 0. AUG 56700. 338.60 1214. 516. 0. SEP 56700. 338.60 506. 475. 0. YEAR 411. 380. 0. YR 1991 OCT 56700. 338.60 163. 132. 0. NOV 53368. 337.19 79* 104. 0. DEC 48080. 334.95 49. 104. 0. JAN 41870. 332.31 34. 104. 0. FEB 35484. 329.61 20. 104. 0. MAR 28905. 326.12 28* 104. 0. APR 22300. 321.34 24. 104. 0. MAY 17504. 317.79 57. 104. 0. JUN 15700.. 316.50 605. 604. 0. JUL 15700. 316.50 1237. 1206. 0. AUG 56700. 338.60 935. 237. 0. SEP 56700. 338.60 441. 410. 0. YEAR 309. 278. 0. Yk 1992 OCT 56700. 338.60 512. 481. 0. NOV 56700. 338.60 1.94. 163. 0. DEC 54487. 337.66 99. 104. 0. JAN 50798. 336.10 75. 104. 0. FEB 46688. 334.36 61. 104. 0. MAR 42077. 332.40 60. 104. 0. APR 39340. 331.24 89. 104. 0. MAY 46595. 334.32 253. 104. 0. JUN 15700. 316.50 1347. 1835. 0. JUL 15700. 316.50 1873.' 1842. 0. AUG 56700. 338.60 2000. 1302. 0. SEF 56700. 338.60 723. 692. 0. YEAR 612. 581. 0. YR 1993 OCT 56700. 338.60 135. 104. 0. NOV 54261. 337.57 94. 104. 0. DEC 49526. 335.56' se. 1044 0. JAN 43562. 333.03 38. 104. 0. FEB 37897. 330.63 33. 104. 0. MAR 31995. 327.78 39. 104. 0. APR 27711. 325.48 63. 104. 0. MAY 27158. 325.18 126* 104. 0. JUN 15700. 316.50 730. 892. 0. JUL 15700. 316.50 1595. 1564. 0. AUG 56700* 338.60 1363. 665. 0. SEP 56700. 338.60 612. 581* 0. YEAR 411. 380. 04 YR 1994 OCT 56700. 338.60 246. 215. 0. NOV 53963. 337.44 89. 104. 0. DEC 49044. 335.35 55. 104. 0. JAN 42957. 332.77 36. 104. 0. FEB 36904. 330.21 26. 104. 0. MAR 30694. 327.09 34. 104. 0. APR 24063. 323.39 37. 104. 0. MAY 216654 320.83 83. 104. 0. JUN 15700. 316.50 579. 648. 0. JUL 15700. 316.SO 1506. 1475. 0. AUG 56700. 338.60 837. 139. 0. SEP 56700. 338.60 5694 .538. 0. YEAR 344. 313. 0. YR 1995 OCT 56700. 338.60 337* 306. 0. NOV 56700. 338.60 172. 141. 0. DEC 56700. 338.60 142. Ill. 0. JAN 53810. 337.38 88. 104. 0. FEB 49867. 335.70 64. 104. 0. MAR 44887. 333.59 54. 104. 0. APR 40841. 331.88 67. 104. 0. MAY 43854. 333.15 184. 104. 0. JUN 15700* 316.50 993. 1435. 0. JUL 15700* 316.50 1621. 1590. 0. AUG 56700. 338.60 12a8. 590. 0. SEP 56700. 338.60 333. 302. 0. YEAR 449. 418. 0. Yl@ 1996 OCT 56700. 338.60 242. 211. 0. NOV 55391. 338.05 113. 104. 0. DEC 54284. 337.58 117. 104. 0. JAN 51333. 336.33 67. 104. 0. FEB 47946. 334.89 74. 104. 0. MAR 43888. 333.17 69. 104. APR 42222. 332.46 107. 104. 0. MAY 56700. 338.60 415. 149. 0. JUN 15700. 316.50 1014. 1672. 0. JUL 15700. 316.50 1562. 1531. 0. AUG 56700. 338.60 1490. 792. 0. SEP 56700. 338.60 772* 741* 0. YEAR 509. 478. 0. YR 1997 OCT 56700. 338.60 436. 405. 0. NOV 56700. 338.60 199. 169. 0. DEC 56700. 338.60 151. 120. 0. JAN 54671. 337.74 102. 104. 0. FEB 50617. 336.02 62. 104. 0. MAR 46375. 334.22 66. 104. 0. APR 45601. 333.89 122. 104. 0. MAY 56700. 338.60 420. 209. 0. JUN 15700. 316.50 1040. 1698. 0. JUL 15700. 316.50 1841. 1810. 0. AUG 56700. 338.60 1664. 966. 0. SEP 56700. 338.60 822. 791. 0. YEAR 582. 551. 0. YR 1996 OCT 56700. 338.60 216. 185. 0. NOV 54023. 337.47 90. 104. 0. DEC 4?165. 335.41 56. 104. 0. JAN 43017. 332.60 35. 104. 0. FEB 37130. 330.30 29. 104. 0. MAR 31227. 327.37 39. 104. 0. APR 25753. 324*10 43. 104. 0. MAY 26983. 325909 155. 104. 0. JUN 15700. 316.50 893. 1052. 0. JUL 15700. 316.50 1477. 1446. 0. AUG 56700. 338.60 1438. 740. 0. SEP 56700. 33B.60 784. 753. 0. YEAR 441. 410. 0. YR 1999 OCT 56700. 338.60 440. 409. 0. NOV 56700. 338.60 205. 174. 0. DEC 55593. 338.13 117. 104t, 0. JAN 52642. 336.88 87. 104. 0. FEB 49199. 335.42 73* 104. 0. MAR 46002. 334.06 .83. 104s 0. APR 43800* 333.13 98. 104. 0. MAY 56344. 338.45 339. 104* 0. JUN 15700. 316.50 764. 1416. 0. JUL 15700. 316.50 1299. 1268. 0. AUG 56700. 338.60 1080. 382. 0. SEP 56700. 338.60 900. 869. 0. YEAR 460. 429. 0. YR 2000 OCT 567004 338.60 203. 172. 0. NOV 53844. 337.39 87. 104. 0. DEC 48679. 335.20 51. 104. 0. JAN 42592. 332.62 36. 104. 0. FEB 36872. 330.19 32. 104. 0. MAR 30601. 327.04 33. 104. 0. APR 25364. 323.79 47. 104. 0. MAY 29607. 326.50 204. 104. 0. JUN 15700. 316.50 1675. 1878. 0. JUL 15700. 316.50 2121s 2090* 0. AUG 56700. 338*60 2743. 2045. 0. SEP 56700t 338t60 1885t 1AS4. YEAR 764. 7334 0. YR 2001 OCT 56700. 338.60 210. 179. 0. NOV 564-03. 338.47 130. 104. 0. DEC 53574. 337.28 89. 104* 0. JAN 49516. 335.55 69. 104. 0. FEB 44740. 333.53 49. 104. 0. MAR 39637. 331.37 52. 104. 0. APR 36900. 330.21 894 104. 0. MAY 50059. 335.78 349, 104. 0. JUN 15700. 316.50 1226. 1773. 0. JUL 15700. 316.50 2084. 20534 0. AUG 56700. 338.60 1621. 923s 0. SEP 56700. 338.60 643. 612. 0. YEAR 555. 524. 0. YR 2002 OCT 56700. 33B.60 239. 208. 0. NOV 53427. 337.21 80. 104. 0. DEC 48755. 335.23 594 104. 0. JAN 43159* 332#86 44. 104. 0. FEB 37939* 330*65 41t 104. 0. MAR 32713. 328.17 50. 104. 0. APR 28191* 325.74 59. 104. 0. MAY 32495, 328.05 205. 104. 0. JUN 15700. 316.50 770. 1021# 0. JUL 15700. 316.50 1405. 1374. 0. AUG 56700. 338.60 1392. 694. 0. SEP 56700. 338.60 531. .500. 0. YEAR 410. 379. 0. YR 2003 OCT 56700. 338.60 497. 466. 0. NOV 56700. 338.60 213. 182. 0. DEC 56700. 338.60 140. 109. 0. JAN 53933. 337.43 90. 104. 0. FEB 49546. 335.57 56. 104. 0. MAR 44135. 333.27 47. 104. 0. APR 41101. 331.99 04. 104. 0. MAY 48910. 335.30 262. 104. 0. JUN 15700. 316.50 62e. 11 15 5. 0. JUL 15700. 316.50 1479. 1448, 0. AUG 56700. 338.60 1168. 470. 0. SEP 56700. 338.60 920. 889. 0. YEAR 469. 438. 0. YR 2004 OCT 56700, 338.60 1269. 238. 0. NOV 55034. 337.89 107. 104. 0. DEC 50853. 3315.12 67. 104. 0. JAN 45442. 333.83 47. 104. 0. FEB 39445. 331628 27. 104. 0. MAR 332356 328.45 34. 104. 0. APR 26630. 324.80 24. 104. 0. MAY 19436. 319.18 18. 104. 0. JUN 15700o 316.50 847. 879. 0. JUL 15700. 316.50 1B15. 1794. 0. AUG 56700. 338.@)O 2008. 1310s 0. SEP 56700. 338.60 551o 520. 0. YEAR 489. 458. 0. YK 2005 OCT 56700. 338.60 301. 270. 0. NOV 56343. 338.45 129. 104* 0. DEC 54376. 337.62 103. 104o 0. JAN 51855* 336.55 94. 104. 0* FEB 48634. 335.18 77. 104. 0. MAR 45314. 333.77 81s 104. 0. APR 43410. 332.97 103. 104. 0. MAY 53924. 337.42 306. 104. 0. JUN 15700* 316*50 1006. 1617. 0. JUL 15700. 316.50 1761. 1730. 0. AUG 56700. 338.60 1820. 1122. 0. SEP 56700. 338.60 354. 323. 0. YEAR 516* 485. 0. YR 2006 OCT 56700. 338.60 180. 149. ot NOV 53725. 337.34 85. 104. 0. DEC 49052. 335.36 59. 104. 0. JAN 43457. 332.99 44. 104. 0. FEB 37515. 330*47 28. 104. 0. MAR 31735. 327.65 41. 104o 0. APR 27034. 325.12 56. 104. 0. MAY 24083. 322.77 87. 104. 0. JUN 15700. 316.50 579s 6B9. 0. JUL 15700. 316.50 1522. 1491. 0. AUG 56700. 338.60 1359. 661* 00 SEP 56700. 338.60 343. 312. 0. YEAR 369. 338* 0. YR 2007 OCT 56700. 338.60 297. 266. 0. NOV 56700. 338.60 196. 165. 0. DEC 54733. 337.77 103. 104., 0. JAN 50429. 335.94 65. 104. 0. FEB 46541. 334.29 65. 104. 0. MAR 41561. 332.18 54. 104. 0. APR 38705. 330.97 87. 104. 0. MAY 50449. 335.95 326. 104. 0. JUN 15700. 316.50 692. 1245. 0. JUL 15700. 316.50 1383. 1352. 0. AUG 56700. 338.60 1038. 340. 0. SEP 56700. 338.60 351. 320. 0. YEAR 391. 360. 0. YR 2008 OCT 55778. 338.21 120. 104. 0. NOV 52684. 336.90 83. 104. 0. DEC 47765. 334.81 55. 104. 0. JAN 41678. 332.23 36. 104. 0. FEB 35180. 329.48 18. 104. 0. MAR 29093. 326.23 36. 104. 0. APR 23917. 322.63 48. 104. 0. MAY 29697. 326.55 229. 104. 0. JUN 15700. 316.no 10.3b. 1239. 0. JUL 15700. 316.50 1786. 1755. 0. AUG 56700. 338.60 1892. 1194. 0. SEP 56700. 338.60 668. 837. 0. YEAR 521. 490. 0. YR 2009 OCT 56700. 338.60 447. 416. 0. NOV 56700* 338,60 223s 192. 0. DEC 56454. 339.50 131. 104. 0. JAN 53872. 337.40 93. 104. 0. FEB 50207. 335.85 69. 104. 0. MAR 45780s 333o97 63. 104. 0. APR 42686* 332.66 83. 104. 0. MAY 50618. 336.02 264. 104. 0. JUN 15700. 316*50 820. 1376. 0. JUL 15700. 316.50 1691. 1660. 0. AUG 56700. 338.60 1320. 622. 0. SEP 56700. 338.60 822. 791. 0. YEAR 506. 475* 0. YR 2010 OCT 56700. 338.60 167. 136. 0. NOV 52654. 336.89 67. 104. 0. DEC 47428. 334.67 50. 104. 0. JAN 41525s 332.17 39. 104* 0. FEB 35527. 329*62 27. 104. 0. MAR 29256. 326.31 33. 104. 0. APR 24674. 323.24 So. 104. 0. MAY 34574. 329.17 296. 104. 0. JUN 15700. 316.50 912. 1199. 0. JUL 15700. 316.50 1512. 1481. 0. AUG 56700o 338.60 1794. 1096. 0. SEP 56700. 338.60 970. 939. 0. YEAR 497. 467. 0. Exhibit C Preliminary Seismic Evaluation LINDVALL, RICHTER & ASSOCIATES EARTHQUAKE SCIENCES AND ENGINEERING PRELIMINARY SEISMIC EVALUATION for EAGLE RIVER DAMSITE Near Eagle River, Alaska July 1, 1981 TABLE OF CONTENTS Page No. � Conclusions . . . . . . . . . . . . . . . . . . . 1 � Tectonic Setting . . . . . . . . . . . . . . . . 2 � Historical Seismicity . . . . . . . . . . . . . . 4 - General . . . . . . . . . . . . . . . . . . 4 - Good Friday Earthquake of 1964 . . . . . . 6 � Major Fault in Region . . . . . . . . . . . . . . 7 Aleutian Trench/Arc . . . . . . . . . . . . 7 � Local Faults in Project Area . . . . . . . . . . 8 - Eagle River Thrust Fault . . . . . . . . . 8 - Knik Fault . . . . . . . . . . . . . . . . 8 - Castle Mountain Fault . . . . . . . . . . . 9 � Seismicity . . . . . . . . . . . . . . . . . . . 9 - State of the Art . . . . . . . . . . . . . 9 - Maximum Credible Earthquakes . . . . . . . 11 - Maximum Credible Bedrock Accelerations 13 - Earthquake Recurrence Probabilities . . . . 15 6 References . . . . . . . . . . . . . . . . . . . 20 Lindvall, Richter & Associates TABLES Page No. Table 1. List of Large Earthquakes in Alaska 4 (M >7.2) 1784-1980 Table 2- Seismic Parameters for Eagle River 13 Damsite, Alaska FIGURES (at end of report) Fig. 1" Generalized fault map of southeast Alaska (Fig. 29 in NAS, 1971, Geology, Part A). Fig. 2. Alaska Seismicity Map (adapted from NOAA World Map'1961-1969, 1974). Fig. 3. (Fig. 30 in NAS, 1971, Geology, Part A.) Epicenters of earthquakes (M >4) in central Alaska during the period 1954-1963. Etc. Fig. 4. (Fig. 29 in NAS, 1971, Geology, Part A.) Idealized vertical section showing selected rock units and structural features of south-central Alaska. Etc. Fig. 5. (Fig. 2 in NAS, 1972, Seismology and Geodesy.) Sections across the Aleutian structural system showing a composite of aftershock hypocenters, etc. Fig. 6. (Fig. 42 in NAS, 1971, Geology, Part A.) Diagrammatic time-sequential cross sections ihrough the crust and upper mantle, etc. Fig. 7. (Fig. 9 in NAS, 1971, Geology, Part A.) Map of south-central Alaska, showing epicenter of March 27, 1974 earthquake, etc. Fig. 8. Contour map for effective peak acceleration. Lindvall, Richter & Associates CONCLUSIONS 1. It is feasible to design and construct a dam at the Eagle River site, from a seismic point of view. 2. The Aleutian Trench/Are seismic zone (plate boundary) appears to be the controlling.tectonic feature at the site. It is a megathrust that underlies the site at about 20 miles depth. It is part of the Circum-Pacific Seismic Belt, and as such, could conceivably cause a maximum credible Richter magnitude earthquake of 8.7. 3. Smaller faults closer to the site (Eagle River Thrust, Knik and Castle Mountain) are not known to be as active nor as significant in terms of seismic design. 4. The seismic design of the dam and appurtenant works should incorporate a 0.4 peak acceleration (see Table 2). Effective peak g would be less, but not less than 0.33 g. 5. Lindvall, Richter & Associates were not asked to provide digitized time histories, ground motions, or site- specific response spectra in this preliminary report. Likewise we were not asked to discuss reservoir-induced seismicity nor liquefaction potential. We would be happy to provide such information if-desired. Lindvall, Richter & Associates TECTONIC SETTING There are two principal earthquake zones in Alaska. These two'zones are part of the seismic belt which rings the Pacific Ocean (Gutenberg and Richter, 1954). One, the Denali fault zone, is generally considered to begin north of Yakutat Bay off.the Gulf of Alaska and to extend southeastward to the west coast of Vancouver Island. Because it lies 120 miles distant from the Eagle River damsite, it will not be dis- cussed further. The other, the Aleutian Trench, is described as following the arc of the Aleutian Islands from their western extremity through the Kenai Peninsula to east of Prince William Sound; it is one of the world's most active seismic zones (Plafker, 1971; St. Amand, 1957; and Figs. 1, 2, and 3 herein). It was near the intersection of these two faults that the 1964 Good Friday earthquake occurred. Fortunately, the previous 7 earthquakes of Richter magnitude 8 or larger that have struck southeast Alaska since 1899 occurred in sparsely populated areas. The historic record going back to the Russian Settlement of 1784 (Sykes et al., 1980), suggests greatearthquakes within the Aleutian Trench/Arc of the Circum-Pacific Seismic Belt at relatively short intervals, so that the entire trench/ arc is involved. Seismic gaps (areas of accumulating strain energy) are eventually plugged. Thus, probably any given Lindvall, Richter & Associates 2. locality within the trench/arc.zone is subject to a great earthquake at least once every few hundred years. The trench is a shallow-dipping subduction zone (Figs. 4, 5, and 6), as revealed by instrumentally recorded aftershock patterns and from the focal depths of several moderate to large earthquakes, including the 1964 event. This means that the megathrust -- the source of great earthquakes -- is as close as 20 miles in a vertical direction, and slightly farther in a horizontal direction. The implication here is that the common design criterion of vertical g equals 75 percent of horizontal g is not necessarily valid; verti- cal and horizontal g should be approximately equal for the Eagle River site. Lindvall, Richter & Associates 3. HISTORICAL SEISMICITY General South-central Alaska, including the eastern Aleutian Trench/Arc, is one of the most active regions in the world. Past large earthquakes suggest a Richter M 8 or greater event every ten years, on the average. Any given area with- in this region, however, may escape extensive damage from a large quake for more than a century, as discussed later. The following list of large earthquakes is representative; those of 1788-1880 are adapted from Sykes et al. (1980). Table 1. List of Large Earthquakes in Alaska (M >7.2) 1784-1980 Richter Date Location M 1788 July 22 55N 160W? 8+ 1788 Aug. 7 55N 160W? 7-8? 1792 57N 152W? 7-8? 1844 --- 57N 152W? 7-8? 1847-48 --- 55N 160W? 8+ 1848 --- 58N 137W? 7-8? 1854 57N 152W? 7-8? 1878 Aug. 29 57N 152W? 7-8? 1880 55N 155W? 7-8? 1896 May -- 61N 144W? 7-8? 1899 July 14 55N 160W 7.7 Lindvall, Richter & Associates 4. Table 1. (contd) List of Large Earthquakes in Alaska (M >7.2) 1784-1980 1899 Sep. 4 60N 142W 8.3 1899 Sep. 10 60N 140W 7.8 (foreshock) 1899 Sep. 10 60N 140W 8.6 1900 Oct. 9 60N 142W 8.3 1901 Dec. 31 52N 177W 7.8 1902 Jan. I 55N 165W 7.8 1903 June 2 57N 157W 8.3 1904 Aug. 27 64N 151W 8.3 1905 Feb. 14 53N 178W 7.9 1906 Aug. 17 51N 17PE 8.3 1907 Sep. 2 52N 173E 7-3/4 .1929 Mar. 7 51N 170W 8.6 1929 July 7 52N 178W 7.3 1929 Dec. 17 52-21N 17lx2E 7.6 1937 July 22 64-3/4N 146-3/4W 7.3 1937 Sep. 3 52JN 177x2W 7.3 .1938 Nov. 10 55-5N 158.4W 8.7 1940 July 14 51-8N 177.5E 7.8 1943 Nov. 3 61.7N 151W 7.3 1947 Apr. 1 52.3N 163.2W 7.4 1948 May 14 54-7N 161W 7.5 1949 Aug. 22 53.6N 133.3W 8.1* 1957 Mar. 9 51-6N 175.4W 8.2 1957 Mar. 12 51-4N 176.9W 7.3 Lindvall, Richter & Associates 5. Table 1. (contd) List of Large Earthquakes in Alaska (M >7.2) 1784-1980 1957 Apr. 19 52.2N.166.3W 7.3 1958 Apr. 7 66.ON 156.6W 7.3 1964 Mar'. 28 61-IN 147.6W 8.5** 1965 Feb. 4 51-3N 178.6E 7.9 1965 Mar. 30 50.6N 177.9E 7.5 1972 July 30 58N 136W 7.6 1979 Feb. 28 60-6N 141.6W 7.4 *Actually, British Columbia (Queen Charlotte Is.) **Revised upward from M 8.4 by C. F. Richter from later data reduction. Good Friday Earthquake of 1964 The earthquake that struck at 5:36 P.M. on March 27 1964, originating an estimated ten to twenty miles below the earth's surface, bad a magnitude of 8.5, established by C. F. Richter, the U.S. Coast and Geodetic Survey, and the U.S. Geological Survey. It released somewhat more energy than the 1906 San Francisco quake. Significant crustal deformation occurred (National Academy of Sciences, 1971, 1972, 1973, and Fig. 7 herein'). Kelleher and Savino (1975) reviewed the records of past earthquakes in this region. They found a seismically quiet period from 1944 to 1954; from 1954 to 1964 there was increased Lindvall, Richter & Associates 6. seismic activity near the rupture zone. Lay and Kanamori (in preparation; personal communication, 1981) suggest that large quakes in the eastern part of the Alaska peninsula can result in 800 km rupture lengths. Eagle River is some 60 miles from the Good Friday epi- center and focus, and as a.result, experienced greatly attenuated intensities -- on the order of MM VII. Had the epicenter been closer to the site, as is possible in future events, the intensity and the ground accelerations could have 'been severe. MAJOR FAULT IN REGION Aleutian Trench/Arc The maximum credible earthquake for the entire region can be reasonably associated with the Aleutian Trench/Arc, an active boundary between two crustal plates of very large dimensions. Indeed, it is appropriate to regard this zone as a imajor part of the Circum-Pacific Seismic.Belt, and to regard the other active faults of south-central Alaska as lesser-order expressions of this broader fault system. Ap- praisal of tectonic activity on this basis leads to results consonant with those derived through application of the criteria listed for the maximum credible earthquakes. Because this is the largest and most active fault zone in the region, the necessity of designating a local or near- Lindvall, Richter & Associates 7. field event on a closer but smaller fault is not necessary. Effective ground accelerations resulting from the smaller faults could be similar to that of the Aleutian Trench/Arc, but the duration of shaking would be shorter. LOCAL FAULTS IN PROJECT AREA Eagle_River Thrust The Eagle River Thrust forms a sinuous trace through the Chugach Mountains (Clark, 1973). It passes within a mile of the proposed damsite. It has apparently been offset by high angle cross faults. Recent activity on this thrust fault is not proven, but is not as critical for project feasibility or for design purposes as the Aleutian Trench/Arc structure, because effective ground accelerations at the site would be comparable but duration of shaking resulting from large event on the Trench/Are structure would be much longer. Knik Fault The existence of the Knik fault was inferred only until recently. Its total length is not k nown, but it exceeds 150 miles. It passes within two miles of the proposed dam- site. Recent activity on this fault is not proven, but it is not as critical for project feasibility or design purposes as is the Aleutian Trench/Are. Effective ground accelera- tions would be in the same range for events on both faults but the longer duration of shaking generated by the Trench/ Are structure makes it the governing event. Lindvall, Richter & Associates Castle Mountain Fault The Castle Mountain (Lake Clark) fault extends for more than 300 miles, and is 25 miles from the damsite at its closest point. It is considered an active fault, but is not as critical for project feasibility or design purposes as the Aleutian Trench/Arc, because of lesser effective accel- erations and shorter duration of shaking. SEISMICITY State of the Art Prior to the San Fernando, California, earthquake of 1971, the worldwide distribution of strong-motion seismographs was such that any earthquake that occurred triggered no more than a, few such instruments, and the great majority of earth- quakes went completely unrecorded by instruments of low enough magnification to provide the desired information. Up to 1971 the library of recorded strong ground motions included records obtained from events ranging widely in magnitude and rupture mechanisms, at a variety of distances and on many different types of foundation material. No more than two or three records on various foundations and at different distances represented any one earthquake. Of this library only a. few records showed strong ground motion of 0.2 gravity acceleration or higher; none were obtained from earthquakes of Richter Magnitude greater than 7.7 (such as the 1952 Kern County event). Lindvall, Richter & Associates 9. It is not surprising, therefore, that the correlations which were attempted among the variables such as the magni- tude of the event, the epicentral (or other) distance, the foundation conditions, and the peak acceleration or spectrum intensity exhibited extreme scatter. In the San Fernando magnitude 6.4 earthquake of February 1971 strong motion records were obtained from more than two hundred instruments, so that, for the first time, patterns of behavior could be sought. Similarly many records were obtained from the 1979 Imperial Valley earthquake of M 6.6. However, even in these circumstances, subsequent analyses exhibit a large diversity of response. Apparently the diverse nature of the source motions and the mechanisms of wave propagation through the varied materials of southern California are extremely complex phenomena. Even the large number of stations at which records were obtained in these earthquakes was not sufficient to enable unequivocal relations to be derived, such as the effect of the record- ing site properties on the accelerations measured. General indications of the attenuation of acceleration amplitudes with distance, however, have been obtained, albeit still with a substantial scatter; different attenuation along different ray paths is also evident. From the point of view, therefore, of establishing a design earthquake at a particular site, a large number of Lindvall, Richter & Associates 10. uncertainties are still pres ent. The peak acceleration may vary by a factor of two. The ground motion selected for particular conditions by different analysts will vary widely, since elements of personal judgment play a large part in the selection process. In particular, instrumental evidence for the strong-motion behavior of the.ground during very large earthquakes, and at close distances to the rupture zone for all earthquake magnitudes, is essentially entirely lacking. It must therefore be pointed out that, whereas the method adopted in this report of arriving at earthquake ground motions at the Eagle River site is felt to be reasonable, conserVative, and in accordance with the current state of practice for similar calculations, there is no guarantee that the ground motion parameters which might occur at the site during some futur& earthquake will correspond precisely to those assumed for use in the dam performance calculations. The previous history of earthquake studies demonstrates that each significant earthquake has appreciably modified existing concepts of both the mechanisms and magnitudes of effects involved. The same procedural consequences will probably follow each future event, especially if it is accompanied by ground motions recorded at many stations. Maximum Credible Earthquakes The magnitude of the maximum credible earthquake for Lindvall, Richter & Associates each fault (Table 2) has been estimated on the basis of the following factors: A. Historic record of seismicity. B. Fault length. C. Maximum rupture length for a single seismic event in historic time. D. Maximum surface displacement for a single seismic event in historic time. E. Behavior of the fault during the past 3 to 5 million years, including distribution and dominant style of movement, cumulative separation or displacement and apparent average rate of slip. F. Inferred role of the fault in the regional tectonic framework during the past 3 to 5 million years. The maximum expectable or probable earthquake magnitude, in this highly seismic region, would be only one---or two- tenths of a magnitude less than the maximum credible earth- quake. Maximum Credible Bedrock Accelerations The peak accelerations shown on Table 2 were derived from judgmental collation of the sources listed plus the judgment derived from many years of experience in this field. Although peak horizontal accelerations were asked for in this report, we recommend effective g (two-thirds peak) be used in design, and such should not be less than 0.33 g, Lindvall, Richter & Associates 12. Table 2. Seismic Parameters for Eagle River Damsite, Alaska P Duration Horizontal Maximum Site strong Probability Total distance credible peak shaking of occurrence Fault length (mi) to site (mi) Richter M 9 (seconds) next 100 years (D 30-200 0.35 @I Aleutian Trench/Arc >2000 20* 8.7 0.4* 60+ High M Denali >1000 120 8.4 0.05 60+ High W 0 1 (horiz. P Eagle River Thrust >100 7.0 0.7 20 Moderate-Low C_@ & vert.) (D Knik >150 2 7.5 0.7 35 Moderate-Low Castle Mountain >300 25 7.8 0.25 35 Moderate-High *Vertical Oistance; vertical acceleration (see text) References Lindvall, Richter & Associates (this report) Hudson et al. (1971) Schnabel and Seed (1973) Hudson and Cloud (1972) Housner (1969) Richter (1958) Housner and Jennings (1973) Von Huene (1972) Page.et al. (1972) Sykes et al. (1980) as also shown by Algermissen and Perkins (1976), Fig. 8 herein. (Newmark and Hall, 1973, suggest 0.33 g for the Alyeska Pipeline design, along with 16 in/sec design velocity for structures.) Peak horizontal g usually represents an isolated spike with a duration so short that large structures do not respond. Digitized time histories would better define effective ground motionsy but we were not asked to provide these in this preliminary report. As discussed previously under Aleutian Trench/Arc, both horizontal and vertical g should be approximately the same for design purposes. A variety of studies has been made relating parameters describing ground motion at a site to its distance from a causative fault or earthquake epicenter (e.g. Schnabel and Seed, 1973; Housner and Jennings, 1973; McGuire, 1974). For earthquakes greater than magnitude 8 originating at distances of the order of 20-30 miles, investigations indicate that peak accelerations of about 0.4 g will be experienced at the s ite, and that the duration of strong ground motions may i exceed 60 seconds. It was considered that the second worst case of ground motion at the site would result from the initiation of a fault rupture at a point on the fault some intermediate distance from the site. With a rupture velocity of a few Lindvall, Richter & Associates 14. kilometers a second, a rupture initiating, say 100 miles away, would reach the stretch of the fault closest to the site in perhaps 30 seconds, pass by, and terminate- at a point on the fault some distance away. Because of the Doppler effect as the rupture moves towards the site, the early stages would be characterized by fairly high frequency shaking, attenuated to some extent by distance. The peak intensity and frequency of shaking would occur at the point of closest approach relatively little diminished by attenu- ation through the ground. Ultimately as the rupture continued at increasing distances, the intensity,of shaking would fall off, to form the tail of the hypothetical record. No ground motion has yet been recorded in conditions matching these requirements, and it is necessary to construct an artificial acceleration history to best represent the cir- cumstances of site and hypothetical earthquake. The largest earthquake for which a strong-motion record has been obtained is still the 1952 Kern County, California, event, for which records of three components were obtained at Taft. Earthquake Recurrence Probabilities As is true for most areas of the world, the historical record is simply-too short to make meaningful extrapolations into -the future, except for specific faults at specific localities. Alaska is not one of these favored places having a long written record. Lindvall, Richter & Associates 15. However, Sykes et al. (1980) have dug into the records of the period of Russian settlement in Alaska, 1784-1867. They have interpreted past major events based on the early descriptions.of damage and'physical changes. Adaptations from this record are shown on Table 1. This record, com- bined with the record of this century, has led Sykes et al. (1980) to suggest a recurrence interval of great earthquakes in the central Aleutian Arc at 50-75 years. McCann et al. (1980) suggest a recurrence interval of 80 years for the Yakataga area; Kanamori (1977a) suggests 220 years recur- rence interval for a repeat of the 1964 event at Prince Willi-am Sound. Elaborate statistical investigations are often applied to draw conclusions about the probable magnitude and frequency of future earthquakes in a given area. Such work adds very little to estimates of risk which may be required prior to establishing a design earthquake. Simpler common- sense evaluation of historical and geological data is desirable; such data, as well as seismographic catalogs, are grossly incomplete from the statistical point of view. Kelleher (1970) indicates a seismic gap (accumulation of strain energy) southwest of the 1964 epicenter, and predicts an earthquake of lesser magnitude than 1964 prior to year 2000. Sykes (1971) suggests a seismic gap exists east of the 1964 epicenter. Either prediction could yield Lindvall, Richter & Associates 16. equal or lesser intensities of shaking at the Eagle River site 'to those caused by the 1964 earthquake. However, after a period of tens of years, the seismic gap falls again back to the Prince William.Sound area -- the closest area to Eagle River that has experienced a great earthquake in recorded history. In using even the most complete catalogs of small events to infer the probability of large ones, it is assumed that where large earthquakes occur occasionally, smaller ones occur progressively more frequent ly, (e.g. Shakal and Willis, 1972; Marachi and Dixon, 1972). This assumption is partially justified, as there appears to be a real relationship of this character for many faults. For the globe as a whole, and for certain local but usually rather large regions, it is commonly put in the form: log N a + bM, where 'IN" is the number of earthquakes with magnitudes near a given magnitude I'M", during an, avE.@rage time interval of a year, while "a" and "b" are constELnts; "b" is necessarily a negative number that usually turns out to be near -2, often about -1.8. It is commonly overlooked, however, that this is a statis- tically general relation only, and that it is subject to many local and temporary exceptions. Certain faults and segments of faults that occasionally are the seats of large earthquakes (e.g., those segments of the San Andreas fault on which the earthquakes of 1857 and 1906 originated) often exhibit Lindvall, Richter & Associates 17. intervals of quiescence, during which even small events are infrequent. The occurrence of small earthquakes is not very useful for estimating earthquake risk in a given locality, unless their epicenters establish the activity of a nearby fault. It is our judgment that formulation of design earthquakes to apply at a given place should not be based upon elaborate estimates of probabilities, which at best are derived from fragmentary and questionable history and statistics. Instead, the few larger known historical earthquakes, together with geological data on active faults, should Pe used to envision seismic occurrences likely to affect a.structure at the locality of concern. In the past century, enough moderate and large earthquakes have occurred in Alaska to define the Aleutian Trench/A@rc, the Denali, and some other faultsas active (Brogan, 1975). Small ear thquakes may be random near-surface crustal adjust- ments, unrelated to recognized faults in the vicinity. Thus, until a given fault ruptures in an earthquake or has.displaced geologically recent deposits, its potential for future activity cannot definitely be known. Such is the case for the Eagle River and Knik faults. If their earthquake return periods were only 300 years, we would not know it because alluviation and eirosion would have destroyed surface displacements, and no one was in the region to record a past event. Also, the Lindvall, Richter & Associates 18. habit of some faults, or segments of faults, may be to cause large earthquakes almost exclusively, and almost never cause small or moderate earthquakes (e.g. San Andreas fault). For these reasons we do,not place strong reliance on most gradu- ated magnitude versus recurrence interval graphs. Therefore, it would be prudent for the entire Eagle River dam installation to be designed to expect, at a minimum, a repeat of the 1964 earthquake, at a somewhat closer proximity, during its useful life. Lindvall, Richter & Associates 19. REFERENCES Algermissen, S.T. and Perkins, D.M., 1976, A probabilistic estimate of maximum acceleration in rock in the contiguous United States: U.S. Geological Survey Open File Report 76-416. Brogan, G.E. et al., 1975, Active faults of Alaska: Tectonophysics, Vol. 29, p. 73-85. Clark, Sandra H.B., 1973, The McHugh Complex of south-central Alaska: U.S. Geological Survey Bulletin 1372-D, 11 p. Davies, J.N. and House, L., 1979, Aleutian subduction zone seismicity, volcano-trench separation and their relation to great thrust type earthquakes: Jour. Geoph. Research. Gedney, L. and Berg, E., 1969, Some characteristics of tectonic stress pattern in Alaska: Geophysical Journal, Vol.. 17, p. 293-304. Gutenberg, B. and Richter, C.F., 1954, Seismicity of the earth and associated phenomena: Princeton University Press, Princeton, N.J., 310 p. Gutenberg, B. and Richter, C.F., 1956, Earthquake magnitude, intensity, energy, and acceleration: Seismological Society of America Bulletin, Vol. 46, p. 105-145. Housner, G.W., 1969, Engineering estimates of ground shaking and maximum earthquake magnitude: Proc. 4th World Conference on Earthquake Engineering, Vol. 1. HousnE@r, G. W. and Jennings, P.D., 1973, Reconstituted earth- quake ground motion at Anchorage: National Academy of Sciences, The Great Alaskan Earthquake of 1964, Engineering Volume, p. 43-48. Hudson, D.E., Brady, A.G., Trifunac, M.D.., Vijiyaraghavan, A., 1971, Strong motion earthquake accelerograms, digitized and plotted data, Vol. II, Part A: California Institute of Tecbnology Earthquake Engineering Research Lab Report No. EERL 71-50. Hudson, D.E., Cloud, W.K., 1973, Seismological background for engineering studies of the earthquake: National Academy of Sciences, The Great Alaskan Earthquake of 1964, Engineering Volume, p. 18-42. Lindvall, Richter & Associates 20. Kanamori, H., 1977a, Seismic and Aseismic slip along sub- duction zones and their tectonic implications,, in Talwani, M., and W.C. Pitman, III, (eds.): Island Arcs, Deep Sea Trenches and Back-Arc Basins, Maurice Ewing Seri-es 1: American Geophysical Union, p. 163-174. Kanamori, H., 1977b, The energy release in great earthquakes: Jour. Geophysical Research, Vol. 82, p. 2981-87. Kelleher, J., 1970, Space-time seismicity of the Alaskan- Aleutian seismic zone: Jour. Geophysical Research, Vol. 75, p. 5745-56. Kelleher, J. and Savino., J., 1975, Distribution of seismicity before large strike slip and thrust-type earthquakes: Jour. Geophysical Research, Vol. 80, p. 260-271. Lay, T., and Kanamori, H., 1981, The asperity model and the nature of great earthquake occurrence, in preparation. Marachi, N.D., Dixon, S.J., 1972, A method for evaluation of seismicity: Proceedings of the International Conference on Microzonation for Safer Construction Research and Application, Vol. 1, p. 379-394. McCann, W.R., Perez, 0. J. and Sykes, L.R., 1980, Yakataga gap, Alaska: seismic history and earthquake potential: Science, Vol. 207, March, p. 1309-1314. McGuire, R.K., 1974, Seismic structural response risk analysis, incorporating peak response regressions on earthquake magni- tude and distance: M.I.T. Dept. of Civil Eng., Rept. R74-51, 371 p. National Academy of Sciences, 1971, 1972, 1973, The Great Alaska Earthquake of 1964: Geology, Seismology and Geodesy, and Engineering, 3 volumes. Newmark, N.M. and Hall, W.J., 1973, Seismic design spectra for Trans-Alaska Pipeline: Fifth World Conference on Earthquake Engineering, Rome, Paper 60. Page, R.A., Boore, D.M., Joyner, W.B. and Coulter, H.W., 1972, Ground motion values for use in the seismic design of the Trans-Alaska Pipeline system: U.S. Geological Survey Circular 672, 23 p. PlafkE@r, G., Tectonics: National Academy of Sciences, The Great Alaskan Earthquake of 1964, Geology Part A., p. 47-123. Lindvall, Richter & Associates 21. Pulpan, H. and Kienle, F., 1979, Western Gulf of Alaska seismic risk: llth Ann. Offshore Technology Conference, Paper. OTC! 3812. Richter, C.F., 1958, Elementary Seismology, W.H. Freeman Co., San Francisco, 768 p. Schnabel, P.B. and Seed, H.B., 1973, Acceleration in rock for, earthquakes in the western United States: Seismolog- ical Society of America Bulletin, Vol. 63, No. 2, p. 501-516. Shakal., A.F. and Willis, D.E., 1972, Estimated earthquake probabilities in the north Circum-Pacific area: Seismological Society of America Bulletin, Vol. 62, p. 1397-1410. Sykes, L.R., 1971, Aftershock zones of great earthquakes, seismicity gaps, and earthquake prediction for Alaska and the Aleutians: Jour. Geophysical Research, Vol.. 76, p. 8021-41. Sykes, L.R., et al., 1980, Rupture zones of great earth- quakes in the Alaska-Aleutian Arc, 1784-1980: Science, Dec. 19, p. 1343-1345. St.-Amand, P., 1957, Geological and geophysical synthesis of the tectonics of portions of British Columbia, the Yukon Territory and Alaska: Geological Society of America Bulletin, Vol. 68, p. 1343-1370. Von Huene, R., 1972, Geologic structure of the-continental margin: National Academy of Sciences, The Great Alaskan Earthquake of 1964, Seismology and Geodesy Volume, p. 277-288. Whitman, R.V. et al., 1975,,Seismic design decision analysis, Jour. Struct. Division, ASCE, Vol. 101, No. ST5. Lindvall, Richter & Associates 22. 146 ALASKA EARTHQUAKE, MARCH 27, 19,64 - --------- UNIT ST4 CIO .1 -.9-FIA 0 br --V .......... . 00- GOOD 0 to m@\ ........... Rim Z_ to LD Ln [941 -fa ',ell ,e 0 C E c N a E A V P 0 R T DA 40 G @TOR AN -S ASKA L LINE 000 SIP %*so* PA Af jow .0 C) M. ot 0 0 ot 0 06 a 20. ..:0: 3pC A 0 F .16 1 0 60 0 % .0 0 C 0 "00 .0 *.1 0 0 L W '6 148 ALASKA EARTHQUAKE, MARCH 27, 1964 170* 165* 160* 155. 350' 145* 3 40' 1 65' 0 0000 00 0 0 1 0 0 QCP 0 0 0 0 > 0 0 v EP 0 > 0 0 0 0 0 0 CA ZA61- RIVE14 0 0 DAM S TE 00 60' 0 0 0 0 6/9 0 A 00 0 0 0 0 0 0 D 0 0 0 O@ o 0 0 & 16000 A 0 0 55* 0 0 0 0 0 6> (Z) 0 C! 0 50 100 MILES 0 0 00 L 0 500 0 50 100 KILOMETERS 0 L 'L j SUBMARINE CONTOURS IN FEET I 30-Epicenters of earthquakes (M @!t 4) in central Alaska during the period January 1954 to h1arch 1963. Shallow deptl (=:-= 70 km) earthquakes indicated by ciricles; intermediate depth 70 km) indicated by triangles. Da-ta after Tobin an6 Sykes (1966). 0 [961 Early Mesozoic and Late Mesozoic Early Cenozoic Late Cenozoic A Mount Spurr older outcrop belt outcrop belt outcrop belt outcrop belt A# CASTLE MTN FAULT ?Aleutian Trench Axis MILES @-Tv CzU PZ Mz J:J MZ KILOMETERS 0 zu Czl CZ2 @Czu and Mzu? 0 fVlZu 110 ";' 10 9 9 20 Czu, Cenozoic rocks, undifferentiated ? -c"fliceanic crust 20 Mzu, Mesozoic rocks, undifferen 7 6ceanic crust and mantle 1 40 0 100 200 MILES 0 100 200 KILOMETERS EXPLANATION Approximate contact Ei Includes possible fault contacts, Dashed where Andesitic extrusive rocks of active or dor- inferred or concealed mant volcanoes A- Thrust or reverse fault Dashed where inferred. Sawiceth on upper plate. Open teeth indicate major fault Late Cenozoic bedded rocks Lighter pattern where projected offshore :01- -r- 0 Steeply dipping fault ca Dashed where inferred. Arrows indicate relative 1E lateral displacement; bar and ball on relatively Early Cenozoic bedded rocks downthrown side Lighter pattern where projected offshore -Z=:- --- Trend lines sl@owing strike of bedding, schistosity, and fol do Late Mesozoic bedded rocks Major faults and faults with known Holocene movement Lighter pattern where projected offshore Asterisk indicates known Holocene movement; double asterisk indicates historic movement No Fault T Data Source I** Fairweather Tocher (1960); Tarr and Martin (1912);Plafker (1967) ER 2. Chugach-St Elias (probable Miller and others (1959, p. 42), Plafker (1967) Paleozoic and early Mesozoic bedded Holocene movement) rocks 3* Denali St. Amand (1957); Hamilton and Myers(1966YGrantz (1966) Lighter pattern where projected offshore 4* Castle Mtn-Lake Clark Martin and Katz (1912, p. 72-75); Kelly (1968, p. 289); Grantz (1965, sheet 8) S. Bruin Bay Burk (1965, p. 139); R. L. Detterman, (oral commun., 1967) Granitic plutonic rocks 6** Patton Bay and Hanning Bay Plafker (1968) 7* Ragged Mtn Miller (1961) 8$ Holitna-Togiak Hoare (1961, p. 608-610) 9. Kenai lineament This paper Undifferentiated rocks I I(possible f964 movement) 29. 41kvil"Mmill"d _s_-P A.."I idealized vertical section showing selected rock units and structural features of south-central Alaska. Indicated displace- ment direction on faults Is the net late Cenozoic movement only. Geology modified from a manuscript tectonic map of Alaska. by P. B. King and from unpublished I'_4 U.S. Geological Survey data; the thickness of crustal layers and the structure shown In the section are largely hypothetical. PARAMETERS OF THE MAIN SHOCK W (L 0 >_ i Ir W Z 0 ir W Z W LL Z D _j (r Z <'n . . 0 :D I- !e Z W U Z Ln @5 t <Z L4L a. J4 <Z W tr 0 _j W T @- 0 _j LT ED U 0- in Ln Ln MT 0 uj LT & MT K Ti L 5 LTt A P 10- K? 10 KM KM VERTICAL EXAGGERATION X5 0 25- 50- U io Z W 75--_ X Z 100- < 125 - NO VERTICAL EXAGGERATION W _j 150- 0 < I 0 50 KM KM I I I I _L_j FIGURE2 Section across the Aleutian structural System showing a composite of aftershock hypocenters from the latitude of Middleton Isla the southern end of Kodiak Island. Geology generalized from Burk (1965), Moore (1969), and seiSMiC-TCfr2ction data from Shor (1964). P, P rocks; LTR, lower Triassic rocks; LI, MJ, and UJ, lower, middle, and upper Jurassic rocks; Ji, Jurassic intrusive rocks; K, Cretaceous rocks; Ll MT, lower and middle Tertiary rocks; UT, upper Tertiary rocks; Ti, lower Tertiary intrusive rocks. Hypocenters are from Tobin and Sykes (E where location 0 is most accurate, 0 is of intermediate accuracy, and A is least accurate. Contours are strain telease from aftershocks of the I Alaska earthquake in I 00-unit intervals of equivalent magnitude 3.0 earthquakes per 157 km2. Individual aftershocks greater than magnitude shown with filled circles (o). Queried contacts extrapolated from seismic-refraction stations suggest a lower and middle Tertiary thickened sc4 possibly a continental rise, seaward of a similar Cretaceous feature. 166 ALASKA EARTHQUAKE, MARCH 27, 19.64 ,,Aleutian Volcanic Arc PATTON BAY FAULT), ? iAleutian Trench 0 t,,,,sJ%one -Continental crust Me - Ir1rred subcrustal flow dire tion Ocea n1c crust and mantle Transverse shortening, thickening, clownwarping? 0 or ? . . . ........... .......... ........... ... ....... ............ . ...... . . ............. ...? Hypothetical strain ellipse howing postulated orientation of principal pressure axes and potential shear planes resulting from a shear couple Horizontal extension Horizontal shortening Slight - - - - - - - - - - uplift Subsidence Uplift Subsidence'? C ? C 0 100 200 MILES I I I 0 100 200 KILOMETERS I I I. HORIZONTAL AND VERTICAL SCALE 42-Djagranunatic time-sequential cross sections through the crust and upper mantle in the northern part of the region affeeb by the 1964 earthquakii A, Relatively unstxained condition after the last major earthquake. B, Strain buildup stage duxii which the continental margin is shortened amd downwarped. C, Observed and inferred displacements -at time of the ea@rtbqual during which a segment of the continental margin is thrust s6award relative to the continent. Datum is the upper surface of tl crust beneath the cover of water and low-velocity sediments. Vertical displacements at the surface, which are indicated by It profiles and by arrows showing sense and relative amount of movement, are about X 1,000 scale of the fig-ure. M SETTING AND EFFECTS 15 156* 14A 64. 154* 152* 150* 148* 146' Z LANATION It , 0 6 or mom 6 or more. yl 63, less th. Epicenters and mmagnitude' .(@ichter Of BhOC13@ March Z7,196d* J Joe ROVER 16AM 62' cr) A -e@ AL Vr 9 ..Ip@. -.0 . @. - , - A 4 Iff" T@ff @ - ---M - I * Z AxIcborage 40 OKI IF 1. 10 C C C 0 co CD N-Y. -Homer 00 59, 40f odiak 01 57 rr 7 7-W LOCATION MAP 0 2@ @o @5 100 MILES 56. 0 L 9.-Map of south-cenitral. Alaska, showing epicenter of March 27, 1964, ea-rthquake, major aftershocks, and aivas of tectonic land-leviil changes. Most aftershocks centered In the area of uplift along the continental margin of the Aleutian Trench between the Trinity Isdands and the epicenter of the main shock. Data chiefly from reports by the U.S. Coazt and Geo- detic Survey (19(4, 1965a), Grantz, Plafker, and Kachadoorian (1964), and Plafk-er (1965). 7 [191 0.30. ND (> A 0 A At EAGLIE RIVEK bjk%% srrE ALASKA 00. CONTOUR MAP FOR EFFECTIVE PEAK ACCELERATION I I I Exhibit D Harding-Lawson Associates . Summary of Laboratory Tests LL tie SAMPLE LAB TEST SOURCE CLASSIFICATION RESULTS B-3 @ 85' GRAY SANDY SILT (@L) Moisture Content (M)=30.3% with fibrous organics Atterberg Limits (AL) Plate 3 B-4 @ 35,40 & BROWN SILTY GRAVELLY M = 11.7% 45' (combined) SAND (SP-SM) Particle Size Analysis (PSA) Plate 2 B-5 @ 5 & 101 BROWN SILTY GRAVELLY M= 14.8% (combined) SAND (SP-SM) PSA on Plate 2 B-5 @ 20' GRAY SILT:(ML) M = 24.2% Minus #200 Sieve = 99.8% A.L. on Plate 3 Consolidation (consol) on Plates 4-6 Triaxial Compression Consolidated/Undrained Tx (CU) on Plate-- 13 Effective Stress Paths Plate 16 B-5 @ 25' GRAY SILT (ML) M = '26.9% A.L. on Plate'3 Unconfined Compression (UC) on Plate 17 B-5 @ 35' DARK GRAY SILT (ML) M = 28.3% with trace of silt Minus #200 Sieve = 96.5% B-6 @ 5,10 & GRAY SILTY GRAVELLY M = 13.7% 15' (combined) SAND (SP-SM) PSA on Plate 2 B-6 @ 20' GRAY SILT (ML) M = 21.6% A.L. on Plate 3 Minus #200 Sieve = 99.9% Consol on Plates 7-9 Tx(CU) on Plate 14 B-6 @ 25' GRAY SILT (ML) M = 26.2% Minus #200 Sieve = 99.6% A.L. on Plate 3 Consol on Plates- 10-12 Tx(CU) on Plate 15 B-6 @ 40' GRAY CLAY (CL) M = 24.8% A.L. too quick for liquid limit & non-plastic Unconfined Compression (UC) on Plate 17 ALL SAMPLING BY OTHERS Plate I HAr,DINQ- LAWSON ASSOCIATES SntKARY OF LABORATORY TESTS PLATE Consulting Engineers and Geologists CH2M-HILL EAGLE RIVER DAM PROJECT Eagle River, Alaska Job No.-55AL-M . o8 rl,_@@_Date_ 3Z81 U. S. Slandord Sieve Ovening Size U.S.Standard Sieve Numbers rlydronvtor 3 2 1 3 1 CY 74 -@t 4 8 10 16 2030 405060 100 200 270 LL- too 80 IVF IIIII 70 601-- - Z ca a: 40 40 cc 30 20 I I Es V .11 1 1 111 11 '1'00 10 5 1 0.5 01 005 001 0.005 0 1 GRAIN SIZE IN MILLIMETERS COBBLES SAND SILT OR CLAY @E FINE 1COARSE1 MEDIUM I FINE -71 GRAVEL Symbol Somple Source Clossif ication 0 B-4 @ 35', 40' & 45' (combined) BROWN SILTY GRAVELLY SAND (SP-SM) 0 B-@5 @ 5' & 10' (combined) BRO14N SILTY GRAVELLY SAND (SP-SM) B-6 @ 5', 10' & 15' (combined) GRAY SILTY GRAVELLY SANT (SP-SM) HARDINIG - LAWSON ASSOCIATEIS PARTICLE SIZE ANALYSIS PLATE Co-nsidtbig E72gineers and Geologists CH2M-HILL EAGLE RIVER DAY PROJECT 2 Eagle River, Alaska Job No. 5 5 61 0 9-DB 'L -Appr@@-l --Date C14 CAC 70 60 50 CH x Uj 0 40 z CL Z 10 _--'-A L i n e 20. A I I CL ML) MH' ar OH 10- ML - C LN ML or OL 0 ML 0 10 20 30 AO 50 60 70 80 90 100 LIQUID LIMIT (0,16) Symbol Cass ifi ca "ion and Source Liqu;d Plastic Plcst;citly Passing Limit Limit (%') I-,4-x 00',') 4200 Sleve 0 GRAY SANDY SILT (ML) B-3 @ 85.0 39 26 13 GRAY SILT (I-E) B-5 @ 19.5-20.0 33 26 7 GRAY SILT (ML) B-5 @ 25.0 41 27 14 GRAY SILT (ML) B-6 @ 19.0-19.5 - - Non-plastic 99.9 13 GRAY SILT (ML) B-6 @ 24.5-25.0 39 27 12 99.6 GRAY CLAY (CL) B-6 @ 40.0 36 22 14 HARDING - LA-WSON ASSOCIATES PLA S TI Cl TY CHAR T PLATE Corsulting Engfreers c7id Geolcgists C11-)M-HILL Job No. 5561,009.08 A p p a I e EAGLE RIVER DAM PROJECT Eagle River, Alasl-,a PH ESSU RE (psf x 1000) 0.1 0.2 0.30.40.5 1 2 3 4 5 10 20 30 40 50 765 750 IHIN 1,11 .725 ).700 T -Hi- 0.1 0.2 0.3 0.40.5 1 2 3 4 5 10 20 30 40 50 TYPE OF SPECIMEN Undisturbed (trimmed) BEFORE TEST AFT ER TEST H E 80 '0 28.7 DIAMETER(in.) 2.43 IGHT(in.) 0. MOISTURE CONTENT wo 28.4 Wf % OVERBURDEN PRESS.,Po psf VOID RATIO eo 0.766 ef 0,766 % Sf PR ECONSOL. PRESS., Pc - pst SATURATION so 100 100 % COMPRESSION INDEX,Cc 0.02 DRY DENSITY I@dj 97 p c f @d 97 pcf LL 33 PL 26 PI 7 01 2.75 -CLASSIFICATION GRAY SILT (ML) SOURCE Boring 5 @ 19.2' I +Ifl @4111 HARDING -LAWSON ASSOCIATES CONSOLIDATION TEST REPORT PLATE Consulting Engineers and Geologists. CH21",-HILL EAGLE RIVER DAII PROJECT 4 ,!-,b No. 55 1,002-00-Appr )yk_Cate-2Lu- Eagle River, Alaska T.70 HARDING-LAWSON ASSOCIATES Consolidation: Time Deformation M ca jk tAM a P4 0 111: 4 1 0 ;, asi, it T If R -1j. lilt k 30 ,l : 1_11 HR il MIN ti ttffli- 10 1-1 21 I I ILI 'I!I 50 60 41411 70 t --- I I it 80 _-:3 90 ]IT tft#H I Iffill Iill: ill; iiI 00 ff Job: Eagle River Dam--.- N05561,9.8 Date 81 it BoringB-5 Depth 19.2 ------- I, lit ILI! if 115 1111111111111 F1 I FTM T T t,j By Unit No. IN if lull 11 U PtLATE Load 16,940 psf +100 +100 Load If Hill; Time, Min utes HARDING-LAWSON ASSO,CIATES Consolidation: Time Deformation W Jh Ul 0 0 Ht It J HI 10 -F 'JIU: 7 ;M V 'T TM 30 !7!j it TIMITll F iv fli Ill ii 40 J J. Lf so 1@ p E 7 fl"L,! 60 EM r 70 14 It I Lu I I LH :ff 11L 80 HI -j I-Ij I I I I I i b I. 'I! T I "I P- 90 1 100 L Job:.Eagle River Dam No 5561,9.8 tillf 2 Boring B-5 Depth 19. 2' Date 2/81 @T Ii! By / C--- Unit No. T1 1-1 r 1131M-ti-M- - 1 1111 211 1 1 1111IT!"11 11111111111 Ill i@. I- j -- III ]TM ill1i ILI! 21, TI lu u gi Ij PLATE Load Load-@ sf +100 - @,870 11 ijill, +100 it t! il;' nl Time, Minutes 0 U_ PRESSURE (psf x1000) cx 0.1 0.2 0.3 0.40.5 1 2 3 4 5 10 20 30 40 50 0. 60C- 0.575- -4-Lq I I I _j I f"@ @- - I I I I I -T- 0.550 > 71 111- 0.1 0.2 0.3 0.40.5 1 2 3 4 5 10 20 30 40 50 TYPE OF SPECIMEN Undisturbed (trimmed) BEFORE TEST AFTER TEST MOISTURE CONTENT wo % Wf DIAMETER (in.) 2.-4; HEIGHT(in.) 0.80 23.5 23.8 % eo ef 0.578 OvERSURDEN PRESS,% psf VOID RATIO 0.596 - PRECONSOL.PRESS,,Pc psf SATURATION S, 100 910 Sf 1 100 % COMPRESSION INDEX. Cc DRY DENSITY p c f d 1 108 pcf LL NV PL NP PI NP GSo 2.72 CLASSIFICATION GRAY SILT (ML) SOURCE Boring 6 @ 19.0' T::@F HAIRDING -LAWSON ASSOCIATES CONSOLIDATiON TEST REPORT PLATE Consulting Engineers and Geologists CH2ti-HILL EAGLE RIVER DAM PROJECT 7 Job NO_51@0 - 08 Appr@A_1@- -Cate. 1/81 Eagle River, Alaska HARDING-LAWSON ASSOCIATES Consolidation: Time Deformation 17 N 14 f` fr 18 1 0 It, P111IMif IIIIII U 0 .0 TIT, 30 70 it All 30 90 No5561 9.8 Job: Eagle River Dam - Boring B-6 Depth 19.01 Date 2/8 By Unit No. Load 16,94 psf +1' 0 PLATE Load +100 !Ij@ R@, Ti me, Minutes HARDING-LAWSON ASSOCIATES Consolidation:' Time Deformation 0 r r rrr if 41 -T da 0 ...... 1,111!L I f t 11. 30 it a if IT 40 _LLJ I as :LOT 50 11 60 11111 flN Ih 70 All w if so III: III. fill 1IM11111111iiiiiiii irl -1-d- 111 F: 90 1 +HM I ------- It ... t Y 00 Job:Eagle River Dam - N05561_.,9.8 Date 2/81 Boring B-6 Depth 19.0 it ITV By Unit No. Load 0 sf +100 IUL 14 1N PLATE Tli, 7=1_1 Load +100 Time, Minutes 0 PRESSURE (psf x1000) w 0.1 [email protected] 0.3 0.40.5 1 2 3 4 5 10 -20 30 40 50 0.770 0.750 N1- 0.725 0.700 > IL 0.680 0.1 0.2 0.3 0.4 0.5 1 2 3 4 5 10 20 30 40 50 TYPE OF SPECIMEN Undj5 urbed (trimmp BEFORE TEST AFTER TEST d@-f- W01 2R-9 % -f 29, ? % DIAMETER (in.) 80 MOISTURE CONTENT OVERBURDEN PRESS,% p3f VOID RATIO eo 0-77o 0-758 PRECONSOL. PR ESS, Pc - P3f SATURAT40N S, 100 % Sf 100 % COMPRESSION INDEX.Cc 0.03 DRY DENSITY Xd 97 pcf Y T 97 pcf PL 1 12 Cis 2.74 LL 39 27 p CI-ASSIFICATION GRAY SILT-ftt) SOURCE Boriu 6 @ 24.3' - HARD ING - 1;-AWSO N:AASSOCIA-4 ES PLATE C IAT, E I-S CONSOLIDATION TEST REPORT 'lo'g" nd Ge "t3 t 3181 S S107 Consulting Engineers and Geologz'st3 @ee, CH2M-HILL EAGLE RIVER DAIM PROJECT 10 Eagle River, Alaska 51,004.08 Appr:-@-'Vate HARDING-LAWSON ASSOCIATES Consolidation: Time - Deformation 4 '4 cd V a 0 .6 !:@ lo L, ALI ill, _L 41, ,20 HIM IL 11 till 30 lit. lid 1@'l Is U M. 11 50 IM 3 0 T @i 71 70 LII lit 80 I E. - go 114 T_ 100 Job: Eagle River Dam No 5561,9.8 -6 Depth24.3' Date 2/81 Boring B It i@i[ I J1 a "TIP By Unit No. It Ll Ij fli PLATE 16,940 psf +100 Load. t Load +100 hil III! IN Time, Minutes HARDING-LAWSON ASSOCIATES Consol i dati on: Time Deformation A IN Id -k (A n 0 _1T UL I 1 :1. A- 0 aL !L L IhY IF ILI 111MI111 f 111111111 A I I 30 1 w lit ifl, L M T'n 10 11111 Ili 2 1 0 mil Li@ Eli fif., 60 T It 70 Flit T I 80 I -TTTTt a :I M if go w TIM t -it -Hi 00 TILL Job:Eaq1e River Dam No 5561,9.8 IN :1 Boring B-6 Depth 24. 3! Date_?_L8 hh Unit No. T i J1 lllfldl, I I @@l T R'-M I% fill MIM111 If i@ Load _jj,qZO _p s f +JoO ll@ PLATE Load +100 12 L I I,j cl Time, Minutes ctv=N 12@SPLV ',ADAL'd aL623 E)lllep@Tv_jdd'V_80 * 600'T 95 9 -ON 103CObd WVO UJAH 319V3 --- IIIH-W HO VIS150109D PUZ) ffuz;lnsuoo A% ?iyld IHOd3d ISEUNOISS38dWOD -1VIXVRAl 0@]NlVLJC1Nn-c)Divcil-l0SN0D salvloossv Nos/A%(-j-DNlc3mv" ,S*61 0 9 MUFA08 ow) ills AV89 3:)8nos I ?iollr:)12!ssvr-l:) SL"Z L Id 92 -1 EE 1_1 ;Dd Vol PA ;3d 101 lpx AIISN30 Abo 0% s0*0 ALVH NI"IS UDL - - UUL Os sd OaO % IS % I N0uvNn_,7s "D "SS2ZJcl N0IlVGI_ICISN0:) StS),o J12 969*0 Oa - 011-VU 010A ;r cl .9 ru ad'-SS38d 14308n9d@iAO ot 8 94 J. % 6'SZ ON. 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IPX AIISN:?() A80 GO'O 31178 NIV81S OIL) I - - 001 OS d OmT-.Q % is % Notivun-,vs "SS28d NOUVOMSNOD 95S U 9L9 0 -0 RJ'_SS32jd N30anam3Ao ax 9 96 ru!)-L % IN31NO:) 3@!n.Lstovj H0I3Hj CUI)B3.13VNIVIO (pawwp4) paqjn4SL .LS31 831-4V IS31 3?30@!39 Pull N3V4I:)3dS -40 3d@kl (0/ g, 91 01 9 0 i r MI j -VO- _-E T E _Z'O (> 1> P@ +ILT -T-1 i- C> rr IL 4 @Ir_ _Z'O 41 AL _VO L__L LL 9 L-4+ LL I + - Sro L.- LL 4f- TE 01 0 Cal 0 I- t 0 4- A.1 I II I I i I II I IIIA t VO J; -0 ---- L + I I _Z'O -7 - - - - t,'O L - - - - - -- - - - 90 :L L 16000- CALCULATIONS tan 0' ff= 1. 972 If= 1. 643 C nfi @.Zw 0'=380 T.is defined as inter- 0'=420 9 14000. cept of tangent line C1=0 C =0 on Y-axis 12000- 1000-0- KEY B-5. @ 19.51 B-6 @ 19.51 B-6 @ 24.51 0Maximum Effective Principle 6000. Stress Ratio 4000 - 2000- 0 0 2000 4000 6000 8000 10000 12000 L13, Psf HARDING - LAWSON ASSOCIATr--S EFFECTIVE STRESS PATHS PLATE Cop?sulting Engineers and Geologists CH2M-HILL EAGLE RIVER DAM PROJECT Eagle River, Alaska 16 Job No._5_5&_1,_009.0 -1-Appr: _041@ate I I It I I DIAMETER (in): 1.40 0 3 0 HEIGHT (in): 3.00 x MOISTURE CONTENT (0/6)'. 26, 9 m 7- DRY DENSITY (pcf): 104 2a. CEL L PRESSURE (psf): NONE (n 4A+ SHEAR STRENGTH(psf): 1230 X SAMPLE sOU[@cE: Boring 5 fa 25.0' DESCRIPTION:- GRAY SILT (ML) 0 0 5 10 15 m 25 AXIAL STRAIN NO HT DIAMETER (in) - 1-40 HEIGHT 3.00 X 10 MOISTURE CONTENT 24.8 U) DRY DENSITY (Pcf)* 112 cn 8 co CELL PRESSURE (psf): NONE -A 1 1 1 1 w x SHEAR STRENGTH (psf)* 4530 6 0 SAMPLE SOURCE: Boring 6 @ 40.0' 4 I It I II t I I I DESCRIPTION: GRAY SILT IML) W> 2 0 0 5 10 15 20 25 AXIAL STRAIN M) HARDING-LAWSON ASSOCIATES TRIAXIAL COMPRESSION TEST REPORT C.'oitsultingE72giiicersa,ndGcologists UNCONSOLIDATED - UNDRAINED PLATE CH01-HILL EAGLE RIVER DAM PROJECT 17 Job No. 5561,009.08 -Appr: ate 3/81 Eagle River, Alaska U.S. Standard Sieve Oo on in 9 Size U.S.Standard Sieve Numbers I Hydrometer C14 4 2 1 Y'Z4 ';'@ @b 810 16 903@0405060 w 200270 LA- I T 80 70 60 X I 11N 50 GO t 0 A. X1 I I I I I I I I I I II I N I I I I cc I I I t I I I I I I 1 11 11 30 'IN 10 K, I LI-L /0 - 01 005 a a I 01"00 0 5 0.5 QO( 0.005 GRAIN SIZE IN MILLIMETERS COBBLES GRAVEL I SAND SILT OR CLAY I FINE JCOARSEJ MEDIUM I FINE Symbol Sample Source Classification * Bulk Composite Sample (Bulk Bags 1W) BROWN SANDY GRAVEL (GW) ' 1E ) BROWN SANDY GRAVEL (GW) * Bulk Composite Sample (A S&G * B-1 @ 5'+ and 10'+(2 jars) GRAY SANDY SILT (ML) 0 B-2 @ 5'+ (1 jar) GRAY SANDY SILT (ML) HARDING -L.AWSON ASSOCIATIES PARTICLE SIZE ANALYSIS PLATE 8ulting Engine R T AGLE Gon ers and Geologi8t8 E IVER DAM PROJEC Eagle River, Alaska Job No. 5561,009.08 _AP 9;-ate 2/19/81 J I L- Exhibit E CH2M HILL Summary of Laboratory Tests A 60-- CH 50-- x UJ a I I z 40- 0000, >- CL 30 - A Line -J 20- (L MH or OH 10 CL - ML-\ or OL 0- M L 10@0 I i i 0 10 20 30 @O 50 60 70 80 90 100 LIQUID LIMIT % SAMPLE DATA: GRAY CLAY ( CL B-5 SS-8 DEPTH = 45 ft. LIQUID LIMIT = 36 % PLASTIC LIMIT = 21 % PLASTICITY INDEX = 15 NATURAL MOISTURE CONTENT 22% GRAY SILT (ML B-6 SS-4 DEPTH = 30 ft. LIQUID LIMIT = 49 % PLASTIC LIMIT = 28 % PLASTICITY INDEX = 21 NATURAL MOISTURE CONTENT 29% Figure E-1 Plasticity Chart Eagle River Dam Project 10 0 0 x LL (0 UNCONFINED COMPRESSIVE 0. STRENGTH, qu=5040 psf C0 w cc 4 x 2 0 5 10 15 20 25 30 AXIAL STRAIN ( % RATE OF STRAIN 0.055 in/min SAMPLE DATA: GRAY CLAY CL DEPTH z 30 ft. INITIAL DIAMETER 1.43 in. INITIAL HEIGHT = 2.91 in. NATURAL MOISTURE CONTENT 32% DRY DENSITY = 92 pct Figure E-2 Unconfined Compression Test B-5 SS-5 Eagle River Dam Project 10- '-VMPREESSIVE ST ENGTH, qu=s600 psf 8 0 0 0 V- x LL co co co co 4 -J x 2 oy 0 10 15 20 25 30 AXIAL STRAIN ( % RATE OF STRAIN 0.055 in/min SAMPLE DATA: GRAY SILT ( ML DEPTH = 30 ft. INITIAL DIAMETER z 1.39 in. INITIAL HEIGHT = 2.81 in. NATURAL MOISTURE CONTENT 32% DRY DENSITY 93 pcf Figure E-3 R Unconfined Compression Test B-6 SS-4 Eagle River Dam Project NOAA COASTAL SERVICES CTR LIBRARY 3 - 6668 -1-41106,65"""8"",