[Federal Register Volume 59, Number 107 (Monday, June 6, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-13561]


[[Page Unknown]]

[Federal Register: June 6, 1994]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[AD-FRL-4891-8]

 

National Emission Standards for Hazardous Air Pollutants for 
Source Categories: Aerospace Manufacturing and Rework

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule and notice of public hearing.

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SUMMARY: The proposed standards would limit emissions of hazardous air 
pollutants (HAP) from new and existing commercial, civil, and military 
aerospace original equipment manufacturing (OEM) and rework facilities 
that are major sources of HAP emissions. A major source is defined in 
section 112(a) of the Clean Air Act as amended in 1990 (Act) as a 
source that emits, or has the potential to emit, considering controls, 
10 tons per year (tpy) or more of any individual HAP or 25 tpy or more 
of any combination of HAP. The proposed standards implement section 
112(d) of the Act, which requires the Administrator to regulate 
emissions of the HAP listed in section 112(b) of the Act. Many of these 
pollutants are emitted from cleaning, primer, topcoat, depainting, and 
chemical milling maskant operations. These operations are being covered 
in the proposed rule. The intent of the proposed rule is to protect the 
public health by requiring new and existing major sources to control 
HAP emissions to the level attainable by the maximum achievable control 
technology (MACT). The EPA is also proposing Method 309 with the 
standards. Method 309 would be used to determine the rolling material 
balance period for carbon adsorbers.
    A public hearing will be held, if requested, to provide interested 
persons an opportunity for oral presentation of data, views, or 
arguments concerning the proposed standards.

DATES: Comments: Comments must be received on or before August 5, 1994.

ADDRESSES: Comments: Comments should be submitted (in duplicate, if 
possible) to: Air and Radiation Docket and Information Center (6102), 
ATTN: Docket No. A-92-20, U.S. Environmental Protection Agency, 401 M 
Street, SW., Washington, DC 20460. Public Hearing: If anyone contacts 
the EPA requesting a public hearing, the hearing will be held at the 
EPA Office of Administration Auditorium in Research Triangle Park, 
North Carolina. Persons wishing to present oral testimony must contact 
Ms. Julia Latta, Standards Development Branch (MD-13), U.S. 
Environmental Protection Agency, Research Triangle Park, North Carolina 
27711, telephone number (919) 541-5578 by July 1, 1994.
    Background Information Document: The background information 
document (BID) may be obtained from the U.S. EPA Library (MD-35), 
Research Triangle Park, North Carolina 27711, telephone number (919) 
541-2777. Please refer to ``National Emission Standards for Hazardous 
Air Pollutants for Source Categories: Aerospace Manufacturing and 
Rework--Background Information for Proposed Standards,'' EPA-453/R-94-
036a.
    Docket: Docket No. A-92-20, containing supporting information used 
in developing the proposed rule, is available for public inspection and 
copying between 8:30 a.m. and 3:30 p.m., Monday through Friday, at the 
EPA's Air and Radiation Docket and Information Center, Waterside Mall, 
room 1500, 1st Floor, 401 M Street, SW., Washington, DC 20460. A 
reasonable fee may be charged for copying.

FOR FURTHER INFORMATION CONTACT: For information concerning the 
proposed rule, contact Ms. Vickie Boothe at (919) 541-0164, Standards 
Development Branch, Emission Standards Division (MD-13), U.S. 
Environmental Protection Agency, Research Triangle Park, North Carolina 
27711.

SUPPLEMENTARY INFORMATION: The information presented in this preamble 
is organized as follows:

I. Background
II. Summary of the Proposed Rule
    A. Applicability
    B. Proposed Standards for Affected Sources
    C. Compliance Dates
    D. Compliance Extensions
    E. Compliance Testing and Monitoring
    F. Recordkeeping and Reporting Requirements
III. Summary of Environmental, Energy, and Economic Impacts of the 
Proposed Rule
    A. Emission Reductions
    B. Secondary Environmental Impacts
    C. Energy Impacts
    D. Cost Impacts
    E. Economic Impacts
IV. Process Descriptions and Control Technologies
    A. Process Descriptions
    B. Control Techniques
V. Rationale for the Proposed Rule
    A. Regulatory Development Process for NESHAP
    B. Determining Maximum Achievable Control Technology (MACT) 
``Floors''
    C. Selection of Pollutants and Source Category(ies)
    D. Selection of Emission Points Covered by the Proposed Rule
    E. Selection of the Basis for the Proposed Rule
    F. Selection of the Format of the Proposed Rule
    G. Selection of Emission Test Methods and Monitoring 
Requirements
    H. Selection of Recordkeeping and Reporting Requirements
    I. Selection of Compliance Deadlines
    J. Operating Permit Program
    K. Solicitation of Comments
VI. Administrative Requirements
    A. Public Hearing
    B. Docket
    C. Executive Order 12866
    D. Paperwork Reduction Act
    E. Regulatory Flexibility Act
    F. Clean Air Act Section 117
    G. Regulatory Review
VII. Statutory Authority

    The proposed regulatory text is not included in this Federal 
Register notice, but is available in Docket No. A-92-20 or by written 
or telephone request from the Air and Radiation Docket and Information 
Center (see ADDRESSES). This notice with the proposed regulatory 
language is also available on the Technology Transfer Network (TTN), 
one of EPA's electronic bulletin boards. The TTN provides information 
and technology exchange in various areas of air pollution control. The 
service is free, except for the cost of a phone call. Dial (919) 541-
5742 for up to a 14,400 bps modem. If more information on TTN is 
needed, call the HELP line at (919) 541-5384.

I. Background

    The Act requires, under section 112, that EPA evaluate and control 
emissions of HAP. The control of HAP is to be achieved through 
promulgation of emission standards under sections 112(d) and (f) for 
categories of sources that emit HAP. Pursuant to section 112(c) of the 
Act, EPA published in the Federal Register the initial list of source 
categories that emit HAP on July 16, 1992 (57 FR 31576). This list 
includes major and area sources of HAP that the EPA intends to regulate 
before November of the year 2000.
    For the purposes of the proposed rule, aerospace industries refers 
to all facilities that manufacture aerospace vehicles or components and 
all facilities that rework (including repair) these aerospace vehicles 
or components. Aerospace vehicle or component is defined as any 
fabricated part, processed part, assembly of parts, or completed unit 
of any aircraft including, but not limited to, airplanes, helicopters, 
missiles, rockets, and space vehicles.
    Section 183(b)(3) of the Act requires the Administrator to issue 
control techniques guidelines (CTG) for volatile organic compound (VOC) 
emissions from aerospace coatings and solvents to such levels as the 
Administrator determines are achievable through adoption of best 
available control measures (BACM). The EPA is required to take into 
account the applicable requirements of section 112 in developing the 
guidelines.
    The organic HAP emissions limitations described in the remainder of 
this notice also address the VOC emissions from aerospace coatings and 
solvents. Thus, the control techniques evaluated for the MACT standard 
are also applicable to VOC emissions.
    The EPA traditionally issues a draft CTG containing recommended 
control levels for public comment. Rather than issue a separate draft 
CTG in this case, the EPA is using this notice to request public 
comment on a draft BACM, which is the same as the proposed MACT for 
coatings and solvents. Comments received on the proposed MACT rule will 
also be considered in formulating a final BACM.
    The information described here will also serve to provide guidance 
to the States for developing VOC rules to meet other Clean Air Act 
requirements.
    Certain low-usage coatings were not addressed in the NESHAP. These 
coatings are adhesives, sealants, and 30 specialty coatings which 
represent less than 6 percent of the total HAP emissions from the 
industry. Also, the EPA data analyses indicate that the MACT floor for 
these coatings would be no control. The EPA is requesting public 
comment on the need for a separate CTG providing guidance for the 
control of these coatings.

II. Summary of the Proposed Rule

    Table 1 provides an overview of the proposed rule, including 
applicability; the standards for each affected source; test methods and 
procedures; and monitoring, recordkeeping, and reporting requirements.

  Table 1. Summary of Subpart GG of 40 CFR Part 63--National Emission Standards for Aerospace Manufacturing and 
                                                Rework Facilities                                               
----------------------------------------------------------------------------------------------------------------
         Affected source                     Requirement                             Description                
----------------------------------------------------------------------------------------------------------------
Aerospace Facilities............  Applicability: General            This rule applies to facilities engaged in  
                                   Information.                      original equipment manufacture and rework  
                                                                     of aerospace components and assemblies and 
                                                                     that are major sources as defined in 40 CFR
                                                                     part 63. Specific operations are covered by
                                                                     the rule. (63.741)                         
                                  Estimated Number of Facilities..  Over 2,800 facilities are expected to be    
                                                                     affected by the rule. Applicable SIC codes 
                                                                     include 3720, 3721, 3724, 3728, 3760, 3761,
                                                                     3764, 3765, and 4581.                      
                                  Permit Requirements.............  1. Major sources required to obtain         
                                                                     operating permit in State where facility is
                                                                     located according to procedures in 40 CFR  
                                                                     part 70 and applicable State regulations.  
                                                                     (63.741(d))                                
All Affected Sources............  Standards.......................  1. Comply with Secs. 63.4 through Sec. 63.6 
                                                                     of the General Provisions of 40 CFR part   
                                                                     63, Subpart A.\1\ (63.743(a))              
                                                                    2. Submit an operation and maintenance plan.
                                                                     (63.743(b))                                
                                                                    3. Obtain approval to use control device not
                                                                     listed in this subpart. (63.743(c))        
                                                                    4. Wastes subject to RCRA are exempt from   
                                                                     the waste storage and handling requirements
                                                                     of this subpart. (63.741(e))               
                                  Compliance Dates................  As provided for in the General              
                                                                     Provisions,\2\ within 3 years after the    
                                                                     effective date for existing sources and no 
                                                                     later than the standards' effective date or
                                                                     upon startup, as appropriate, for new and  
                                                                     reconstructed sources. (63.749(a))         
                                  Test Methods and Procedures.....  See individual affected sources. Also,      
                                                                     comply with Sec. 63.7 of the General       
                                                                     Provisions. (63.750(q))                    
                                  Monitoring Requirements.........  See individual affected sources. Also,      
                                                                     generally same as in Sec. 63.8(f) and (g)  
                                                                     of the General Provisions. (63.751(e) and  
                                                                     (f))                                       
                                  Recordkeeping Requirements......  Comply with Sec. 63.10 of the General       
                                                                     Provisions.\3\ (63.752(a))                 
                                  Reporting Requirements..........  1. Comply with Secs. 63.9 and 63.10 of the  
                                                                     General Provisions.\4\ (63.753(a)(1) and   
                                                                     (3))                                       
                                                                    2. Operating permit application can be used 
                                                                     for initial notification. (63.753(a)(2))   
Cleaning Operations.............  Standards.......................  Housekeeping measures for all cleaning      
                                                                     operations at a facility subject to this   
                                                                     subpart. Measures address placing solvent  
                                                                     laden cloth or paper in closed containers, 
                                                                     storing fresh and used cleaning solvent in 
                                                                     closed containers, and minimizing losses   
                                                                     during handling and transfer. (63.744(a))  
                                  Test Methods and Procedures.....  None.                                       
                                  Monitoring Requirements.........  None.                                       
                                  Recordkeeping Requirements......  The name, HAP content of each cleaning      
                                                                     solvent, and supporting documentation.     
                                                                     (63.752(b)(1))                             
                                  Reporting Requirements..........  Semiannual                                  
                                                                    1. New cleaning solvents that contain no    
                                                                     HAP. (63.753(b)(1)(i))                     
                                                                    2. Discontinued cleaning solvents.          
                                                                     (63.753(b)(1)(ii))                         
Hand-Wipe Cleaning Operations...  Standards.......................  1. Except for spray gun cleaning, all hand- 
                                                                     wipe cleaning solvent must meet either a   
                                                                     composition requirement or have a vapor    
                                                                     pressure less than 45 mm Hg. (63.744(b))   
                                                                    2. List of cleaning operations exempt from  
                                                                     composition and vapor pressure             
                                                                     requirements. (63.744(e))                  
                                  Test Methods and Procedures.....  1. Composition determination through        
                                                                     manufacturer's data. (63.750(a))           
                                                                    2. Vapor pressure determination through     
                                                                     readily available sources if single        
                                                                     component; ASTM E 260-85 for multiple      
                                                                     component solvents. (63.750(b))            
                                  Monitoring Requirements.........  For enclosed spray gun cleaners, visual     
                                                                     inspection for leaks at least once per     
                                                                     month. (63.751(a))                         
                                  Recordkeeping Requirements......  1. If complying with composition            
                                                                     requirements, name, data/calculations, and 
                                                                     annual volumes. (63.752(b)(2))             
                                                                    2. If complying as result of vapor pressure,
                                                                     name, vapor pressure, data/calculations/   
                                                                     test results, and monthly volumes.         
                                                                     (63.752(b)(3))                             
                                                                    3. For ``non-compliant'' cleaning solvents  
                                                                     used in exempt operations, daily volumes by
                                                                     operation, and parts/assemblies cleaned.   
                                                                     (63.752(b)(4))                             
                                  Reporting Requirements..........  Semiannual                                  
                                                                    1. Noncompliant solvent usage.              
                                                                     (63.753(b)(1)(iii))                        
                                                                    2. New solvents and vapor pressure or       
                                                                     composition. (63.753(b)(1)(iv))            
                                                                    Annual                                      
                                                                    3. Everything is in compliance.             
                                                                     (63.753(b)(2))                             
Spray Gun Cleaning..............  Standards.......................  1. Use one of four specified techniques or  
                                                                     an equivalent. (63.744(c))                 
                                                                    2. For enclosed spray gun cleaners, repair  
                                                                     as soon as practicable, but within 15 days.
                                                                     (63.744(c)(1)(ii))                         
                                  Test Methods and Procedures.....  None.                                       
                                  Monitoring Requirements.........  None.                                       
                                  Recordkeeping Requirements......  Record all leaks, including source          
                                                                     identification and dates leaks found and   
                                                                     repaired. (63.752(b)(5))                   
                                  Reporting Requirements..........  Semiannual                                  
                                                                    1. Noncompliant spray gun cleaner used.     
                                                                     (63.753(b)(1)(v))                          
                                                                    2. Leaks of enclosed spray gun cleaners not 
                                                                     repaired within 15 days of detection.      
                                                                     (63.753(b)(1)(vi))                         
                                                                    Annual                                      
                                                                    3. Everything is in compliance.             
                                                                     (63.753(b)(2))                             
Flush Cleaning..................  Standards.......................  Operating procedures specify emptying into  
                                                                     enclosed container or collection system or 
                                                                     equivalent. (63.744(d))                    
                                  Test Methods and Procedures.....  None.                                       
                                  Monitoring Requirements.........  None.                                       
                                  Recordkeeping Requirements......  None.                                       
                                  Reporting Requirements..........  Annual                                      
                                                                    Everything is in compliance. (63.753(b)(2)) 
Primer and Topcoat Application    Standards.......................  Uncontrolled Primers                        
 Operations.                                                        1. Organic HAP content limit: 350 grams/    
                                                                     liter (2.9 lbs/gallon)(less water) as      
                                                                     applied. (63.745(b)(1))                    
                                                                    2. VOC content limit: 350 grams/liter (2.9  
                                                                     lbs/gallon) (less water and exempt         
                                                                     solvents) as applied. (63.745(b)(2))       
                                                                    Uncontrolled Topcoats                       
                                                                    3. Organic HAP content limit: 420 grams/    
                                                                     liter (3.5 lbs/gallon)(less water) as      
                                                                     applied. (63.745(b)(3))                    
                                                                    4. VOC content limit: 420 grams/liter (3.5  
                                                                     lbs/gallon) (less water and exempt         
                                                                     solvents). (63.745(b)(4))                  
                                                                    Uncontrolled Primers and Topcoats           
                                                                    5. Primers and topcoats can achieve         
                                                                     compliance through: (1) being below limit  
                                                                     in themselves or (2) average with compliant
                                                                     primers. (63.745(d))                       
                                                                    6. Primers and topcoats cannot be averaged  
                                                                     together. Controlled and uncontrolled      
                                                                     coatings cannot be averaged together.      
                                                                     (63.745(d)(2)(ii) and (d)(2)(iii))         
                                                                    Controlled Primers and Topcoats             
                                                                    7. If control device is used, must be       
                                                                     designed to capture and control all        
                                                                     emissions from the application operation   
                                                                     and must achieve an overall control        
                                                                     efficiency of at least 81%. (63.745(c))    
                                                                    All Primers and Topcoats                    
                                                                    8. Specific application techniques must be  
                                                                     used. If alternative is sought, can only be
                                                                     used if emissions are less than or equal to
                                                                     HVLP or electrostatic spray application    
                                                                     techniques as demonstrated under actual    
                                                                     production conditions. (63.745(e)(1))      
                                                                    9. All application equipment must be        
                                                                     operated according to manufacturer's       
                                                                     specifications. (63.745(e)(2))             
                                                                    10. Exemptions from 8 above provided for    
                                                                     certain situations. (63.745(e)(3))         
                                                                    11. Operating requirements for the          
                                                                     application of primers that contain        
                                                                     inorganic HAP, including control with      
                                                                     either particulate filters or waterwash and
                                                                     shutdown if pressure falls outside         
                                                                     manufacturer's specified operating limits. 
                                                                     (63.745(f)(1) through (4))                 
                                                                    12. Exemptions from 11 provided for certain 
                                                                     application operations. (63.745(f)(5))     
                                  Performance Test Periods and      1. Test Periods For compliant coatings: each
                                   Tests.                            30-day period. For ``averaged'' coatings:  
                                                                     each 24-hour period. For ``controlled''    
                                                                     coatings, non-carbon adsorber: three 1-hour
                                                                     runs. For ``controlled'' coatings, carbon  
                                                                     adsorber: each rolling period.             
                                                                     (63.749(d)(1))                             
                                                                    2. Performance tests. Initial performance   
                                                                     test for all control devices to demonstrate
                                                                     compliance with overall control efficiency 
                                                                     requirement. (63.749(d)(2))                
                                  Test Methods and Procedures.....  1. Organic HAP level determination          
                                                                     procedures. (63.750(c) and (d))            
                                                                    2. VOC level determination procedures.      
                                                                     (63.750(e) and (f))                        
                                                                    3. Overall control efficiency of carbon     
                                                                     adsorber determined using mass balance     
                                                                     calculation in 40 CFR 60.433; for other    
                                                                     control devices, determine capture         
                                                                     efficiency and destruction efficiency. For 
                                                                     capture efficiency, use Procedure T in     
                                                                     Appendix B to 40 CFR 52.741 for total      
                                                                     enclosures and 40 CFR 52.741(a)(4)(iii)    
                                                                     procedures for all other enclosures.       
                                                                     (63.750(g) and (h))                        
                                                                    4. For alternative application methods,     
                                                                     first determine emission levels for initial
                                                                     90-day period using only HVLP or           
                                                                     electrostatic. Then use alternative        
                                                                     application method for period of time      
                                                                     necessary to coat equivalent amount of     
                                                                     parts with same coatings. Alternative      
                                                                     application method may be used when        
                                                                     emissions generated during the test period 
                                                                     are less than or equal to the emissions    
                                                                     generated during the initial 90-day period.
                                                                     Dried film thickness must be within        
                                                                     specification for initial 90-day period.   
                                                                     (63.750(i))                                
                                  Monitoring Requirements.........  1. Temperature sensors with continuous      
                                                                     recorders for incinerators, and install,   
                                                                     calibrate, maintain, and operate           
                                                                     temperature monitors according to          
                                                                     manufacturer's specifications. (63.751(b)) 
                                                                    2. Continuously monitor pressure drop across
                                                                     filter or waterwash. (63.751(c))           
                                  Recordkeeping Requirements......  1. Name and organic HAP and VOC contents for
                                                                     all primers and topcoats. (63.752(c)(1))   
                                                                    2. For ``compliant'' coatings, organic HAP  
                                                                     and VOC contents as applied, data/         
                                                                     calculations used to determine them, and   
                                                                     monthly usage. (63.752(c)(2))              
                                                                    3. For ``averaged'' coatings, daily values  
                                                                     of HAP and VOC contents (Ha and Ga) and    
                                                                     data calculations used to calculate Ha and 
                                                                     Ga. (63.752(c)(3))                         
                                                                    4. For ``controlled'' coatings              
                                                                     (incinerator), overall control efficiency  
                                                                     and incinerator temperature(s).            
                                                                     (63.752(c)(4))                             
                                                                    5. For ``controlled'' coatings (carbon      
                                                                     adsorber), overall control efficiency and  
                                                                     length of rolling period and all supporting
                                                                     data/calculations. (63.752(c)(5))          
                                                                    6. Pressure drop across filters/waterwash   
                                                                     once per shift, and acceptable limits.     
                                                                     (63.752(d))                                
                                  Reporting Requirements..........  Semiannual                                  
                                                                    1. All instances where organic HAP/VOC      
                                                                     levels were exceeded. (63.753(c)(1)(i) and 
                                                                     (ii))                                      
                                                                    2. Control device exceedances (out-of-      
                                                                     compliance). (63.753(c)(1) (iii), (iv) and 
                                                                     (v))                                       
                                                                    3. Periods when operation not immediately   
                                                                     shut down due to pressure drop being       
                                                                     outside limits. (63.753(c)(1)(vi))         
                                                                    4. New control devices. (63.753(c)(1)(vii)) 
                                                                    Annual                                      
                                                                    5. Number of times the pressure drop limits 
                                                                     were exceeded. (63.753(c)(2))              
                                                                    6. Everything is in compliance.             
                                                                     (63.753(c)(2))                             
Depainting Operations...........  Applicability...................  Applies to the entire aerospace vehicle.    
                                                                     Does not apply to parts or units normally  
                                                                     removed. Wings and stabilizers always      
                                                                     covered. (63.746(a))                       
                                  Standards.......................  1. Unless exempted, no organic HAP are to be
                                                                     emitted from depainting operations. (63.746
                                                                     (b)(1), (b)(3))                            
                                                                    2. Requirement to minimize HAP during       
                                                                     periods of non-chemical based equipment    
                                                                     malfunction. (63.746(b)(2))                
                                                                    3. Use of organic HAP-containing strippers  
                                                                     for spot stripping and decal removal       
                                                                     limited to 26 gallons per aircraft per year
                                                                     for commercial aircraft and 50 gallons per 
                                                                     aircraft per year for military aircraft.   
                                                                     (63.746(c))                                
                                                                    4. Operating requirements for depainting    
                                                                     operations generating airborne inorganic   
                                                                     HAP, including control with particulate    
                                                                     filters that are at least 99% efficient.   
                                                                     (63.746(d))                                
                                  Performance Test Periods and      1. For no organic HAP emissions: each 24-   
                                   Tests.                            hour period. (63.749(f)(1))                
                                                                    2. For spot stripping and decal removal     
                                                                     usage limits: each calendar year.          
                                                                     (63.749(f)(1))                             
                                                                    3. Initial performance test to demonstrate  
                                                                     compliance with percent reduction          
                                                                     efficiency requirement for particulate     
                                                                     filters. (63.749(f)(2))                    
                                  Test Methods and Procedures.....  1. Use manufacturer's data (or approved     
                                                                     alternative) to determine organic HAP      
                                                                     content. (63.750(j))                       
                                                                    2. Procedures provided for determining      
                                                                     gallons of HAP containing stripper used for
                                                                     aircraft. (63.750(k))                      
                                                                    3. Use EPA Method 5 to determine particulate
                                                                     filter control efficiency. (63.750(l))     
                                  Monitoring Requirements.........  Continuously monitor pressure drop across   
                                                                     filter. (63.751(d))                        
                                  Recordkeeping Requirements......  1. Name, organic HAP content and supporting 
                                                                     documentation, and monthly volume of all   
                                                                     organic HAP-containing chemical strippers. 
                                                                     (63.752(e)(1))                             
                                                                    2. List of parts/assemblies normally        
                                                                     removed. (63.752(e)(2))                    
                                                                    3. For non-chemical based equipment, name   
                                                                     and type, and malfunction information      
                                                                     including dates, description, and          
                                                                     alternative methods used. (63.752(e)(3))   
                                                                    4. For spot stripping and decal removal,    
                                                                     annual volume used, annual average volume  
                                                                     per aircraft, and all data/calculations    
                                                                     used to calculate volume per aircraft.     
                                                                     (63.752(e)(4))                             
                                                                    5. The pressure drop across the filter once 
                                                                     per shift, pressure drop limits specified  
                                                                     by manufacturers, and control efficiency   
                                                                     including test results/data/calculations.  
                                                                     (63.752(e)(5))                             
                                  Reporting Requirements..........  Semiannual                                  
                                                                    1. Emission of organic HAP from nonexempted 
                                                                     depainting operations. (63.753(d)(1)(i))   
                                                                    2. New and reformulated chemical strippers  
                                                                     and HAP contents. (63.753(d)(1) (ii), (iii)
                                                                     and (iv))                                  
                                                                    3. New non-chemical based depainting        
                                                                     techniques. (63.753(d)(1)(v))              
                                                                    4. Malfunction information on non-chemical  
                                                                     based techniques including dates,          
                                                                     description, and alternative methods used. 
                                                                     (63.753(d)(1)(vi))                         
                                                                    5. Periods when operation not immediately   
                                                                     shut down due to pressure drop being       
                                                                     outside limits. (63.753(d)(1)(vii))        
                                                                    6. List of new/discontinued aircraft models 
                                                                     and, for new models, list of parts normally
                                                                     removed for depainting.                    
                                                                     (63.753(d)(1)(viii))                       
                                                                    Annual                                      
                                                                    7. Exceedances of average annual volume     
                                                                     limits for spot stripping and decal        
                                                                     removal. (63.753(d)(2)(i))                 
                                                                    8. Everything is in compliance.             
                                                                     (63.753(d)(2)(ii))                         
                                                                    9. Number of times the pressure drop limits 
                                                                     were exceeded. (63.753(d)(2)(iii))         
Chemical Milling Maskant          Applicability...................  Applies only to operations using Type II    
 Application Operations.                                             chemical milling etchants (63.747(a))      
                                  Standards.......................  Uncontrolled Maskants                       
                                                                    1. Organic HAP emissions: 160    
                                                                     grams/liter (1.3 lbs/gallon) (less water)  
                                                                     as applied. (63.747(c)(1))                 
                                                                    2. VOC emissions: 160 grams/liter
                                                                     (1.3 lbs/gallon) (less water and exempt    
                                                                     solvents) as applied. (63.747(c)(2))       
                                                                    3. Maskants can achieve compliance through: 
                                                                     (1) being below limits by themselves or (2)
                                                                     averaging with compliant maskants.         
                                                                     (63.747(e))                                
                                                                    4. Both controlled and uncontrolled maskants
                                                                     cannot be averaged together.               
                                                                    Controlled Maskants                         
                                                                    5. If control device is used, must be       
                                                                     designed to capture and control all        
                                                                     emissions from maskant operation and must  
                                                                     achieve an overall control efficiency of at
                                                                     least 81%. (63.747(d))                     
                                  Performance Test Periods and      1. Test Periods. For compliant maskants:    
                                   Tests.                            each 30-day period. For ``averaged''       
                                                                     maskants: each 24-hour period. For         
                                                                     ``controlled'' coatings, carbon adsorber:  
                                                                     each rolling period. For ``controlled''    
                                                                     coatings, non-carbon adsorber: three 1-hour
                                                                     runs. (63.749(g)(1))                       
                                                                    2. Initial performance test required for all
                                                                     control devices to demonstrate compliance  
                                                                     with overall control efficiency            
                                                                     requirement. (63.749(g)(2))                
                                  Test Methods and Procedures.....  Procedures provided essentially identical to
                                                                     those for primers and topcoats for organic 
                                                                     HAP and VOC content levels. Use of Method  
                                                                     309 for determining rolling period for     
                                                                     carbon adsorber. (63.750(m)-(p))           
                                  Monitoring Requirements.........  Same as for primers and topcoats if         
                                                                     incinerators are used.                     
                                  Recordkeeping Requirements......  Same as for primers and topcoats.           
                                                                     (63.752(f))                                
                                  Reporting Requirements..........  Semiannual                                  
                                                                    1. Exceedances of organic HAP/VOC levels.   
                                                                     (63.753(e)(1)(i) and (ii))                 
                                                                    2. Control device exceedances (out of       
                                                                     compliance). (63.753(e)(1)(iii))           
                                                                    3. New maskants. (63.753(e)(1)(iv))         
                                                                    4. New control devices. (63.753(e)(1)(v))   
                                                                    Annual                                      
                                                                    5. Everything is in compliance.             
                                                                     (63.753(e)(2))                             
Waste Handling and Storage        Applicability...................  Wastes that are subject to RCRA are exempt  
 Operations.                                                         from the requirements of this subpart.     
                                                                     (63.741(e))                                
                                  Standards.......................  Unless subject to RCRA, work practice       
                                                                     requirements to minimize spills during     
                                                                     handling and transfer and storage in close 
                                                                     containers. (63.748)                       
                                  Test Methods and Procedures.....  None.                                       
                                  Monitoring Requirements.........  None.                                       
                                  Recordkeeping Requirements......  Identification of each waste stream, whether
                                                                     or not it is subject to RCRA, and          
                                                                     supporting documentation. (63.752(g))      
                                  Reporting Requirements..........  Semiannual                                  
                                                                    1. Any change in RCRA status of waste       
                                                                     stream, any new waste stream, and its RCRA 
                                                                     status. (63.753(f)(1))                     
                                                                    Annual                                      
                                                                    2. No new waste streams and no change in    
                                                                     RCRA status of existing waste streams.     
                                                                     (63.753(f)(2))                             
----------------------------------------------------------------------------------------------------------------
\1\The EPA promulgated regulations for subpart A of 40 CFR 63, which were published in the Federal Register on  
  March 16, 1994 at 59 FR 12408.                                                                                
\2\Ibid.\3\Ibid.\4\Ibid.                                                                                        

A. Applicability

1. Description of the Source Category
    The proposed rule would apply to each aerospace manufacturing and 
rework facility that is a major source, as defined under section 112(a) 
of the Act. A major source is one that emits or has the potential to 
emit, considering controls, 9.1 megagrams per year (Mg/yr) (10 tpy) or 
more of any hazardous air pollutant or 22.7 Mg/yr (25 tpy) or more of 
any combination of hazardous air pollutants for all activities 
conducted at the facility. An aerospace facility is defined as a 
facility that produces in any amount an aerospace vehicle or component, 
or a facility that reworks (or repairs) these vehicles or components. 
Aerospace operations at any major source that conduct both aerospace 
and non-aerospace work would be subject to the proposed standards, 
regardless of the relative proportion of aerospace and non-aerospace 
work at the facility.
    While the proposed rule applies only to major sources, the EPA 
requests comment on whether all or some of its requirements should be 
applied to non-major sources. The Agency solicits available information 
from state and local air pollution control agencies and others on the 
nature, number and location of non-major aerospace facilities, the 
quantities and types of hazardous air pollutants they emit, the impact 
of these emissions on health and the environment, and the extent to 
which these emissions already are controlled. Comments also are 
requested on the economic and other impacts that would result from 
applying requirements of the proposed rule to these smaller sources.
    In general, aerospace facilities are covered by the SIC codes 
listed in Table 2. However, facilities classified under other SIC codes 
may be subject to the proposed standards if the facility meets the 
definition of a major source and the definition of an aerospace 
facility.
    Based on information obtained through the Federal Aviation 
Administration and the U.S. Department of Commerce--Bureau of the 
Census, there are an estimated 2,869 aerospace facilities that will be 
subject to the proposed standards. Of this number, 1,395 manufacture or 
rework commercial products, and 1,474 manufacture or rework military 
products. The combined HAP emissions from these facilities are 
estimated to be over 189,000 Mg/yr (208,000 tpy).
    In addition to these facilities, there are numerous subcontractors 
that manufacture or rework aerospace vehicles or components. The 
subcontractors may work directly for the 

               Table 2.--Aerospace Manufacturing SIC Codes              
------------------------------------------------------------------------
 SIC Code                            Description                        
------------------------------------------------------------------------
3720        Aircraft and Parts.                                         
3721        Aircraft.                                                   
3724        Aircraft Engines and Engine Parts.                          
3728        Aircraft Parts and Equipment.                               
3760        Guided Missiles, Space Vehicles, and Parts.                 
3761        Guided Missiles and Space Vehicles.                         
3764        Space Propulsion Units and Parts.                           
3769        Space Vehicle Equipment.                                    
                                                                        
                        Aerospace Rework SIC Code                       
                                                                        
4581        Airports, Flying Fields, and Services.                      
------------------------------------------------------------------------

OEM or rework facilities, or indirectly through first line 
subcontractors. Since many of these subcontractors perform various 
types of work, they are often classified under non-aerospace SIC codes. 
Consequently, an estimate of the number of subcontractors cannot be 
made. One company alone, however, employs the services of over 5,000 
subcontractors.
2. Affected Sources
    The proposed rule would limit organic HAP emissions from the 
following sources at aerospace facilities: cleaning operation, primer 
application operation, topcoat application operation, depainting 
operation, chemical milling maskant application operation, and the 
handling and storage of waste. The proposed rule would also limit 
inorganic HAP emissions from primer, topcoat, and depainting 
operations.
    Organic HAP emissions from primer, topcoat, and chemical milling 
maskant application operations occur from the evaporation of the 
solvent contained in the coatings. These emissions occur during the 
application of the coatings on aerospace vehicles or parts, which may 
take place in large open areas, such as hangars, or in partially or 
fully enclosed spaces, such as within spray booths.
    Organic HAP emissions from cleaning and depainting operations occur 
from the evaporation of the volatile portion of the cleaning solvents 
or chemical strippers. Cleaning emissions are nearly always fugitive in 
nature and occur at essentially every processing step. Emissions from 
depainting are typically fugitive in nature since the operation is 
carried out within a large hangar or in open tanks.
    Organic HAP emissions from waste occur from evaporation of the 
volatile portion of the waste while it is being handled or stored. 
These emissions are fugitive in nature, occurring from each waste 
container.
    Inorganic HAP emissions from primer and topcoat application 
operations occur during the application of the primer or topcoat. These 
inorganic HAP emissions are paint particulates, commonly referred to as 
``overspray,'' that do not adhere to the surface being coated. Like the 
organic HAP emissions from the operations, the emissions of the 
inorganic HAP occur in large open areas, such as hangars, or in 
partially or fully enclosed spaces, such as within spray booths.
    Inorganic HAP emissions from depainting operations occur from most 
non-chemical methods, such as plastic media blasting, used to strip an 
aerospace vehicle. (Chemical stripping techniques do not release 
inorganic HAP.) These emissions occur as particulates generated during 
the blasting process. The operation is typically carried out within a 
large hangar equipped with a ventilation system and particulate 
filtration device (e.g., a baghouse). The inorganic HAP that are 
released from the depainting operations are primarily found in the 
paint being stripped, although some stripping media may contain trace 
amounts of inorganic HAP.

B. Proposed Standards for Affected Sources

    In addition to the standards for affected sources as discussed 
below, the proposed rule contains general standards. The general 
standards stipulate that all affected sources subject to the proposed 
rule are also subject to, as appropriate, Sec. 63.4, Sec. 63.5, and 
Sec. 63.6 of subpart A of 40 CFR part 63.1 However, certain time 
frames specified in these sections have been changed in the proposed 
rule as follows:
---------------------------------------------------------------------------

    \1\The EPA promulgated regulations for subpart A of 40 CFR part 
63, which were published in the Federal Register on March 16, 1994 
at 59 FR 12408.
---------------------------------------------------------------------------

    (1) All affected sources shall submit any request for an extension 
of compliance not later than 12 months before the affected source's 
compliance date regardless of whether sources are included in emissions 
averaging or not, rather than not later than 18 months before the 
affected source's compliance date for sources that are including 
emission points in an emissions average as provided for in 
Sec. 63.6(i)(4)(i)(B),
    (2) The Administrator (or the State with an approved permit 
program) will notify the owner or operator in writing of his/her 
intention to deny approval of a request for an extension of compliance 
submitted under either Sec. 63.6(i)(4) or (i)(5) within 60 calendar 
days after receipt of sufficient information to evaluate the request, 
rather than notifying the owner of his/her approval or intention to 
deny approval of a request for an extension of compliance within 30 
calendar days as provided for in Sec. 63.6(i)(12)(i) and 
Sec. 63.6(i)(13)(i). In addition, if the Administrator does not notify 
the owner or operator in writing of his/her intention to deny approval 
within 60 calendar days after receipt of sufficient information to 
evaluate a request for an extension of compliance, then the request 
shall be considered approved,
    (3) The Administrator (or the State) will notify the owner or 
operator in writing of the status of his/her application submitted 
under Sec. 63.6(i)(4)(ii) (that is, whether the application contains 
sufficient information to make a determination) within 30 calendar days 
after receipt of the original application and within 30 calendar days 
after receipt of any supplementary information that is submitted, 
rather than 15 calendar days as provided for in Sec. 63.6(i)(13)(i). In 
addition, if the Administrator does not notify the owner or operator in 
writing of the status of his/her application within 30 calendar days 
after receipt of the original application and within 30 calendar days 
after receipt of any supplementary information that is submitted, then 
the information in the application or the supplementary information is 
to be considered sufficient upon which to make a determination,
    (4) Each owner or operator is to be provided 30 calendar days to 
present additional information to the Administrator after he/she is 
notified of the intended denial of a compliance extension request 
submitted under either Sec. 63.6(i)(4) or Sec. 63.6(i)(5), rather than 
15 calendar days as provided for in Sec. 63.6(1)(12)(iii)(B) and 
Sec. 63.6(i)(13)(iii)(B),
    (5) Each owner or operator who has submitted an extension request 
application under Sec. 63.6(i)(5) is to be provided 30 calendar days to 
present additional information or arguments to the Administrator after 
he/she is notified that the application is not complete, rather than 15 
calendar days as provided for in Sec. 63.6(i)(13)(ii), and
    (6) A final determination to deny any request for an extension 
submitted under either Sec. 63.6(i)(4) or Sec. 63.6(i)(5) will be made 
within 60 calendar days after presentation of additional information or 
argument (if the application is complete), or within 60 calendar days 
after the final date specified for the presentation if no presentation 
is made, rather than 30 calendar days as provided for in 
Sec. 63.6(i)(12)(iv) and Sec. 63.6(i)(13)(iv).
    In addition, the proposed rule requires each owner or operator who 
uses a control device or equipment to control HAP emissions to prepare 
an operation and maintenance plan in accordance with Sec. 63.6 of 
subpart A of 40 CFR part 63.2 In addition to the information 
required in Sec. 63.6, the proposed rule requires that the owner or 
operator of the control device or equipment include the following 
information: (1) The operation and maintenance criteria for each air 
pollution control device or equipment, including a standardized 
checklist to document the operation and maintenance of the equipment; 
(2) a systematic procedure for identifying malfunctions and for 
reporting them immediately to supervisory personnel; and (3) procedures 
to be followed to ensure that equipment or process malfunctions due to 
poor maintenance or other preventable conditions do not occur.
---------------------------------------------------------------------------

    \2\Ibid.
---------------------------------------------------------------------------

    The general standards also state that an owner or operator who uses 
an air pollution control device or equipment not listed in the proposed 
rule must submit to the Administrator for approval a description of the 
device, test data verifying the performance of the device or equipment 
for HAP and/or VOC emissions, appropriate operating parameters that 
would be monitored to establish compliance with the proposed standards, 
and a copy of the inspection and maintenance plan required under 
Sec. 63.6 of 40 CFR part 63.
    Finally, Sec. 63.6(g) of subpart A of 40 CFR part 63 allows an 
owner or operator of an affected source to use alternative means of 
compliance. This allows the development and use of new technology not 
known or not demonstrated at the time the rule was promulgated.
    The affected sources for the proposed standards are defined as 
follows: (1) Each cleaning operation (all hand-wipe cleaning operations 
constitute an affected source, each spray gun cleaning operation 
constitutes an affected source, and all flush cleaning operations 
constitute an affected source); (2) each primer application operation, 
which includes all primer applications at the facility; (3) each 
topcoat application operation, which includes all topcoat applications 
at the facility; (4) each depainting operation, which includes all 
depainting of the outer surface of aerospace vehicles at the facility; 
(5) each chemical milling maskant application operation, which includes 
all chemical milling maskant applications at the facility for 
subsequent use in Type II chemical milling etchants; and (6) each waste 
storage and handling operation, which includes all waste handling and 
storage at the facility.
    The proposed standards also specify that HAP-containing waste that 
is subject to the provisions of RCRA would not be subject to the waste 
handling and storage requirements of the proposed standards. The EPA 
included this provision so that the proposed standards would not 
require less strict handling and storage of waste than the RCRA 
requirements.
    The following paragraphs summarize the proposed standards for each 
affected source.
1. Cleaning Operation
    The proposed standards for the cleaning operation, including those 
specific to hand-wipe, spray gun, and flush cleaning operations, would 
apply to all new and existing affected sources. The proposed standards 
would require that all fresh and spent cleaning solvents be stored in 
closed containers and that solvent-laden cloth, paper, or other 
material be placed in bags or other closed containers immediately after 
use. The bags or containers would be required to be kept closed at all 
times (except when depositing or removing material) and of such design 
so as to contain the vapors of the cleaning solvent. In addition, the 
proposed standards would require the owner or operator to implement 
handling and transfer procedures to minimize spills during filling and 
transferring the cleaning solvent to or from enclosed systems, vats, 
waste containers, and other cleaning operation equipment that holds or 
stores fresh or spent cleaning solvents. The above requirements are 
known collectively as housekeeping measures.
    The proposed standards for the hand-wipe cleaning operation would 
require the use of a cleaning solvent that conforms to the approved 
composition list detailed in Table 3 or a cleaning solvent that has a 
vapor pressure less than or equal to 45 millimeters of mercury (mm Hg) 
at 20 deg.C (24.1 in. H2O at 68 deg.F).

                       Table 3.--Composition Requirements for Approved Cleaning Solvents                        
----------------------------------------------------------------------------------------------------------------
      Cleaning solvent type                                   Composition requirements                          
----------------------------------------------------------------------------------------------------------------
Aqueous..........................  Cleaning solvents in which water is the primary ingredient (80    
                                    percent of solvent as applied must be water). Aqueous solvents must be non- 
                                    flammable, non-combustible, and 100 percent soluble in water. Detergents,   
                                    surfactants, and bioenzyme mixtures and nutrients may be combined with the  
                                    water along with a variety of additives such as organic solvents (e.g., high
                                    boiling point alcohols), builders, saponifiers, inhibitors, emulsifiers, pH 
                                    buffers, and antifoaming agents.                                            
Hydrocarbon-Based................  Cleaners that are composed of a mixture of hydrocarbons and oxygenated       
                                    hydrocarbons and have a maximum vapor pressure of 7 mm Hg at 20 deg.C (3.75 
                                    in. H2O at 68 deg.F). These cleaners also contain no HAP or ozone depleting 
                                    compounds.                                                                  
----------------------------------------------------------------------------------------------------------------

    The EPA is proposing a work practice standard for the cleaning of 
spray guns at all new and existing affected sources. The proposed rule 
would require all spray guns to be cleaned by one or more of the 
following methods (or their equivalent): (1) Use of an enclosed spray 
gun cleaning system that is kept closed when not in use, (2) 
nonatomized discharge of solvent into a waste container that is kept 
closed when not in use, (3) disassembly of the spray gun and cleaning 
in a vat that is kept closed when not in use, and (4) atomized spray 
into a waste container that is fitted with a device designed to capture 
atomized solvent emissions. In addition, the EPA is proposing that 
leaks from enclosed spray gun cleaners be repaired as soon as 
practicable but no later than 15 days from when the leak is first 
discovered. The EPA is also proposing a work practice standard for the 
flush cleaning of parts, assemblies, and components of a coating unit. 
Under the proposed rule, each time a part, assembly, or component of a 
coating unit (with the exception of spray guns) is flush cleaned, the 
spent cleaning solvent would be emptied into an enclosed container or 
collection system that is kept closed when not in use.
    The following cleaning operations, which would still be required to 
comply with the proposed housekeeping requirements, would be exempt 
from the proposed cleaning solvent composition and vapor pressure 
requirements:
    (1) Cleaning during the manufacture, assembly, installation, or 
testing of components of breathing oxygen systems that are exposed to 
the breathing oxygen,
    (2) Cleaning during the manufacture, assembly, installation, or 
testing of parts, subassemblies, or assemblies that are exposed to 
strong oxidizers or reducers (e.g., nitrogen tetroxide, liquid oxygen, 
hydrazine),
    (3) Cleaning and surface activation prior to adhesive bonding,
    (4) Cleaning of electronics and assemblies containing electronics,
    (5) Cleaning of aircraft fluid systems that are exposed to the 
fluid,
    (6) Cleaning of fuel cells, fuel tanks, and limited access spaces,
    (7) Surface cleaning of solar cells, coated optics, and thermal 
control surfaces,
    (8) Cleaning during fabrication, assembly, installation, and 
maintenance of upholstery, curtains, carpet, and other textile 
materials used on the interior of the aircraft,
    (9) Cleaning of metallic and non-metallic materials used in 
honeycomb cores during the manufacture of these cores, and cleaning of 
the completed cores used in the manufacture of aerospace vehicles or 
components,
    (10) Cleaning of polycarbonate substrates, and
    (11) Cleaning and solvent usage associated with production, 
research, development, quality control, and laboratory testing.
2. Primer and Topcoat Application Operations
    The proposed standards for primer and topcoat application 
operations would be the same for all new and existing affected sources. 
Standards are being proposed to limit organic and inorganic HAP 
emissions from these operations.
    a. Organic HAP and VOC emissions. The standards being proposed 
would limit the organic HAP emissions from primer application 
operations to an equivalent organic HAP content level of 350 grams of 
organic HAP per liter (2.9 pounds per gallon (lb/gal)) of primer (less 
water) as applied, and from topcoat application operations to an 
equivalent organic HAP content level of 420 grams of organic HAP per 
liter (3.5 lb/gal) of topcoat (less water) as applied. In addition to 
the organic HAP limits, the proposed standards would limit VOC 
emissions from primer application operations to an equivalent VOC 
content level of 350 grams of VOC per liter (2.9 lb/gal) of primer 
(less water and exempt solvents) as applied, and from topcoat 
application operations to an equivalent VOC content level of 420 grams 
of VOC per liter (3.5 lb/gal) of topcoat (less water and exempt 
solvents) as applied. Equivalent organic HAP and VOC content level 
means the calculated organic HAP (or VOC) content of coatings that when 
multiplied by the usage of the coatings yields the amount of organic 
HAP (or VOC) actually emitted to the atmosphere by the use of the 
coatings. Exempt solvents are those organic compounds that have been 
determined by the EPA to have negligible photochemical reactivity.
    The EPA has received information indicating that the organic HAP 
and VOC content limits for topcoats do not represent demonstrated 
technology for exterior commercial topcoats. Consequently, the EPA is 
soliciting comments on whether a separate category should be developed 
for exterior commercial topcoats with HAP and VOC content levels higher 
than the proposed levels for topcoats. These comments should provide a 
technical justification for a higher limit, including why currently 
available commercial topcoats cannot be used by all sources.
    Sources would be allowed to comply with the proposed organic HAP 
and VOC content levels by one or both of the following means: (1) Use 
coatings that individually comply with the organic HAP and VOC levels 
or (2) use any combination of uncontrolled coatings such that the daily 
volume-weighted average organic HAP and VOC contents of these coatings 
comply with the organic HAP and VOC levels for that category (averaging 
of primers and topcoats together is prohibited). Averaging between 
uncontrolled coatings and controlled coatings is prohibited under the 
proposed rule.
    Instead of complying with the proposed organic HAP and VOC content 
levels through compliant coatings or averaging, the proposed standards 
allow the use of control devices provided each control device used for 
the control of organic HAP or VOC emissions from primer or topcoat 
application operations has an overall control efficiency, taking into 
account capture and removal efficiency, of greater than or equal to 81 
percent. In addition, except for incidental emissions that may escape 
from the capture system, the control device cannot be used to control 
only a portion of emissions from a coating operation.
    Compliance with the proposed organic HAP and VOC content level 
standards would be shown on a monthly basis for compliant coatings, and 
on a daily basis for coatings complying by averaging. Compliance for 
control devices other than carbon adsorbers would be shown on a 
continuous basis based on a specific operating parameter or parameters, 
such as temperature for incinerators. When a carbon adsorber is used to 
comply with the proposed standard, compliance with the 81 percent 
overall control efficiency requirement must be demonstrated for each 
rolling material balance period. The length of the rolling period will 
vary from source to source and is determined by the procedure specified 
in proposed Method 309 in the proposed rule. The minimum rolling period 
is one day, and the maximum rolling period is 30 days.
    The EPA is also proposing an equipment standard for the application 
of primers and topcoats. The proposed standard would require the use of 
flow coat, roll coat, brush coat, dip coat, electrostatic attraction, 
or high volume low pressure (HVLP) spray guns other than for the 
exemptions listed below. All application equipment would be required to 
be operated and maintained according to manufacturer's specifications 
at all times.
    The EPA is proposing to allow other application equipment that is 
demonstrated to achieve emission levels equivalent to HVLP or 
electrostatic spray guns. Compliance must be demonstrated by comparing 
the emissions generated by the alternative application method to the 
emissions generated by HVLP or electrostatic application methods under 
actual production conditions. The alternative method must generate 
emissions less than or equal to that generated by HVLP or electrostatic 
spray methods.
    During the alternative application method test period, the owner or 
operator must ensure that the coating dried film thickness is 
equivalent to that applied during the initial 90-day test period. This 
is required to ensure that the owner or operator does not bias the test 
results by applying an excessive amount of coating during the initial 
90-day period and applying a minimal amount of coating during the 
alternative application method test period. The EPA is requesting 
comments on whether the requirements of the proposed standards are 
sufficient to ensure that this situation does not occur. Specifically, 
comments should address whether detailed recordkeeping should also be 
required in order to determine that equivalent dried film thicknesses 
were applied.
    The EPA is proposing to exempt the following situations and 
operations from the proposed equipment standards for the application of 
primers and topcoats, although whatever application equipment is used 
would still be required to be operated and maintained according to 
manufacturers specifications at all times: (1) Any situation that 
normally requires the use of an extension on the spray gun to properly 
reach limited access spaces, (2) the application of coatings that 
contain fillers that adversely affect atomization with HVLP spray guns 
and cannot be applied by any of the specified application techniques, 
(3) the application of coatings that normally have a dried film 
thickness of less than 0.0005 inch and cannot be applied by any of the 
specified application techniques, (4) the use of airbrush application 
methods for stenciling, lettering, and other identification markings, 
and (5) touchup and repair operations.
    b. Inorganic HAP emissions. The standards being proposed for 
inorganic HAP emissions from primer and topcoat application operations 
would apply to those operations that spray apply coatings that contain 
inorganic HAP (usually chromium, cadmium, and selenium). Such 
operations would be required to be performed in a booth or hangar in 
which the air flow is directed across the part or assembly being coated 
and exhausted through one or more outlets. This air stream would be 
required to pass through either dry particulate filters or a waterwash 
system to remove the particulates before exhausting to the atmosphere. 
In addition, the pressure drop across the filter or waterwash would 
have to be continuously monitored. If the pressure drop moves outside 
of the limits specified by the manufacturer to maintain proper 
performance of the dry particulate filters or waterwash system, then 
the operation must be shut down immediately and corrective action 
taken. The process cannot resume until the pressure drop is returned to 
the limits specified by the manufacturer.
    The EPA is requesting comments on whether pressure drop is an 
appropriate parameter on which to make continuous compliance 
determinations with the inorganic HAP emission standards. The 
possibility exists that different filter or waterwash manufacturers may 
specify different pressure drop limits for products with essentially 
the same performance. Since the proposed standards rely on pressure 
drop as the basis for making compliance determinations, such a 
difference would result in different requirements from one facility to 
another. Thus, the EPA is requesting comments specifically on whether a 
standardized pressure drop limit can be established, or if another 
operating parameter exists on which to make compliance determinations 
that would be consistent and enforceable for all types and brands of 
filters and waterwash systems.
    If pressure drop is selected as the parameter to be used to 
determine continuous compliance, then a violation of the standards 
could occur under one of the following conditions: (1) Whenever the 
pressure drop moves outside the limits specified by the manufacturer or 
(2) when the pressure drop is found to be outside the specified limits 
when monitored and recorded once per operating shift. As the proposed 
rule is currently written, a violation would occur in the latter 
situation. The EPA is requesting comments on which of these options, or 
another option, is most appropriate.
    The EPA is proposing to exempt the following list of operations 
from the proposed standards for inorganic HAP emissions from primer and 
topcoat application operations:
    (1) Touch-up of scratched surfaces or damaged paint,
    (2) Hole daubing for fasteners,
    (3) Touch-up of trimmed edges,
    (4) Coating prior to joining dissimilar metal components,
    (5) Stencil operations performed by brush or air brush,
    (6) Section joining, and
    (7) Touch-up of bushings and other similar components.
3. Depainting Operation
    Standards are being proposed for both organic HAP emissions and 
inorganic HAP emissions from depainting. With the exception of the 
proposed standards for spot stripping and decal removal, as discussed 
below, the standards being proposed for depainting would be the same 
for all new and existing affected sources. The proposed standards would 
apply only to the depainting of the outer surface of entire aerospace 
vehicles, including the fuselage, wings, and horizontal and vertical 
stabilizers of the aircraft, and the outer casing and stabilizers of 
missiles and rockets. Standards for the depainting of parts, 
subassemblies, radomes, and parts normally removed from the completed 
vehicle before depainting are not being proposed at this time. However, 
wings and stabilizers would always be required to comply.
    a. Organic HAP emissions. The proposed standards would require that 
there be no organic HAP emissions from the depainting operation. These 
standards could be achieved through the use of (1) chemical strippers 
that contain no organic HAP or (2) media blasting equipment, high 
intensity ultra-violet light blasting, or any other non-chemical 
depainting technique. However, the proposed rule would allow the use of 
organic HAP-containing chemical stripper for spot stripping and decal 
removal. The proposed rule would limit this use of organic HAP-
containing chemical stripper to an average of 26 gallons per aircraft 
for commercial aircraft and 50 gallons per aircraft for military 
aircraft, calculated on an annual basis.
    Non-chemical-based depainting equipment would be required to be 
operated and maintained according to manufacturer's specifications. 
During any period of malfunction, the owner or operator would be 
allowed to use a substitute material to depaint the vehicles. Unless 
the substitute material does not contain any organic HAP, the 
substitute material would not be allowed to be used for more than 14 
consecutive days.
    The proposed rule does not contain an annual limit on the number of 
days a source may use HAP-containing chemical strippers during periods 
of malfunction of non-chemical-based depainting equipment. The EPA is 
requesting comments on whether an annual limit should be imposed and, 
if so, technical justification for the number of days specified by the 
limit.
    b. Inorganic HAP emissions. The proposed rule for inorganic HAP 
emissions would apply to those depainting methods (typically blasting 
methods) that generate airborne particulate emissions, such as dust and 
paint particles, that contain inorganic HAP. The proposed standards 
would require that the depainting operation be carried out in an 
enclosed hangar and that any air stream removed from the depainting 
area be directed through a particulate filter (e.g., panel-type filter 
or baghouse) before exhausting to the atmosphere. This filtration 
system must have a particulate removal efficiency greater than or equal 
to 99 percent, and the pressure drop across the filter must be 
continuously monitored. If the pressure drop moves outside of these 
limits as recorded each operational shift, then the operation must 
immediately be shut down and corrective action taken. The process 
cannot resume until the pressure drop is within the limits specified by 
the manufacturer.
    As described above for primer and topcoat application operations, 
the EPA is requesting comments concerning the appropriateness of using 
pressure drop to make compliance determinations and what action should 
be taken when the pressure drop moves outside of the specified limits.
4. Chemical Milling Maskant Application Operation
    The proposed standards for the chemical milling maskant application 
operation would be the same for all new and existing affected sources 
and applies only to those operations utilizing a Type II chemical 
milling etchant. The proposed standards would limit organic HAP 
emissions to an equivalent organic HAP content level of 160 grams of 
organic HAP per liter (1.3 lb/gal) of chemical milling maskant (less 
water) as applied, and limit the VOC emissions to an equivalent VOC 
content level of 160 grams of VOC per liter (1.3 lb/gal) of chemical 
milling maskant (less water and exempt solvents) as applied. 
Alternatively, as for primer and topcoat application operations, 
control devices that achieve an overall control efficiency of at least 
81 percent and control all emissions (except for incidental emissions) 
may be used.
    Compliance with the organic HAP and VOC content level standards 
would be allowed using one or both of the following means: (1) Use 
chemical milling maskants that individually comply with the organic HAP 
and VOC content levels or (2) use any combination of chemical milling 
maskants such that the daily volume-weighted average organic HAP and 
VOC content levels of these chemical milling maskants used in the 
chemical milling maskant operation comply with the organic HAP and VOC 
content levels. Averaging uncontrolled chemical milling maskants with 
controlled chemical milling maskants, however, is prohibited under the 
proposed rule.
    Compliance with the proposed organic HAP and VOC content level 
standards would be shown on a monthly basis for compliant chemical 
milling maskants and on a daily basis for chemical milling maskants 
complying by averaging. Compliance for control devices other than 
carbon adsorbers would be shown on a continuous basis based on a 
specific operating parameter or parameters, such as temperature for 
incinerators. When a carbon adsorber is used to comply with the 
proposed standard, compliance with the 81 percent overall control 
efficiency requirement must be demonstrated for each rolling material 
balance period. The length of the rolling period will vary from source 
to source and is determined by the procedure specified in proposed 
Method 309 in the proposed rule. The minimum rolling period is one day, 
and the maximum rolling period is 30 days.
5. Handling and Storage of Waste
    The proposed standards for handling and storage of waste would be 
the same for all new and existing facilities. The proposed rule would 
require that the handling and transfer of HAP-containing waste to or 
from containers, tanks, vats, vessels, or piping systems be conducted 
in such a manner that minimizes spills. In addition, all HAP-containing 
waste would be stored in closed containers.

C. Compliance Dates

    The proposed rule would require all existing sources to comply no 
later than three years after the effective date of the standards. In 
addition, the proposed rule adopts the compliance dates specified in 
Sec. 63.6(b) and Sec. 63.6(c) of the General Provisions, 40 CFR part 
63, subpart A.\3\
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    \3\Ibid.
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D. Compliance Extensions

    During development of the aerospace national emission standards for 
hazardous air pollutants (NESHAP), the EPA received comments from the 
regulated community regarding the process that would be used to comply 
with the rule and certain difficulties that were anticipated, 
particularly with the facilities' selection and approval of product 
substitutions for coatings and hand-wipe cleaning solvents. Because of 
the large number of product substitutions that may have to undergo 
testing and qualification at each facility, some facilities may need to 
request a compliance extension.
    Section 63.6(i) of 40 CFR part 63 provides the requirements for 
requesting an extension of compliance with a relevant standard 
established under part 63.\4\ Specifically, Sec. 63.6(i)(4) allows the 
issuance of a permit granting an extension of up to one year to comply 
with the standard, if such additional period is necessary for the 
installation of controls. Section 63.6(i)(4)(i)(B) requires requests 
for compliance extensions to be submitted no later than 12 months 
before the affected source's compliance date.
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    \4\Ibid.
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    The EPA is seeking comment on the significance of the potential 
difficulties of complying with the proposed aerospace NESHAP in the 
allotted 3 years (or 4 years if the one-year extension described above 
is applied for and approved). In addition, the EPA is seeking comment 
regarding how these difficulties can be addressed within the confines 
of the statutory requirements of sections 112(d) and 112(i) of the Act. 
Specifically, the EPA is seeking comment on what types of activities, 
such as technical assistance, can be provided to assist sources 
attempting to come into compliance with the aerospace NESHAP.

E. Compliance Testing and Monitoring

    In addition to the specific testing and monitoring requirements 
specified below for each affected source, the proposed rule adopts the 
testing requirements specified in Sec. 63.7 of the General Provisions, 
40 CFR part 63, subpart A.\5\
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    \5\Ibid.
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1. Test Methods and Procedures
    a. Cleaning operation. For multi-component cleaning solvents, 
compliance with the proposed vapor pressure specifications would be 
determined using E 260-85 to quantify the amount of each organic 
compound in the cleaning solvent. The vapor pressure of each organic 
compound would be determined from the manufacturer's data, standard 
engineering reference texts, or other equivalent methods. The total 
composite vapor pressure would then be calculated by summing the 
partial vapor pressure of each component according to Raoult's Law.
    For single component cleaning solvents, the EPA is proposing that 
vapor pressure data supplied by the manufacturer of the cleaning 
solvent, standard engineering reference texts, or other equivalent 
methods be used for compliance determinations.
    Owners or operators seeking to comply with the cleaning solvent 
approved composition list would have to show compliance using data 
supplied by the manufacturer of the cleaning solvent. The data must 
identify all components of the cleaning solvent and demonstrate that 
one of the approved composition definitions is met.
    b. Primer and topcoat application operations. As noted earlier, the 
proposed standards for organic HAP and VOC emissions would require 
compliance with an equivalent organic HAP content level (pounds of 
organic HAP per gallon of coating (less water) as applied) and an 
equivalent VOC content level (pounds of VOC per gallon of coating (less 
water and exempt solvents) as applied) for primers and for topcoats. 
Compliance with these organic HAP and VOC content levels may be 
accomplished by using compliant coatings, averaging between compliant 
and non-compliant coatings, control devices, or any combination of 
these methods. In addition, the proposed standards would require the 
use of certain application techniques for the application of primers 
and topcoats.
    Test methods and procedures have been identified for compliance 
with the organic HAP and VOC content levels. No test methods or 
procedures have been identified for the application equipment 
requirements; however, a test method has been identified for the 
qualification of alternative application methods.
    Method 24 in appendix A to 40 CFR part 60 would be used to 
determine the VOC content of each primer and topcoat as applied. 
Alternatively, manufacturer's data may be used to determine the VOC 
content of these coatings. However, in the event of any inconsistency 
between manufacturer's data and Method 24 test results, the Method 24 
test results will take precedence.
    The facility may rely on manufacturer's data to determine the 
organic HAP content level of each coating. The total organic HAP weight 
fraction and density of each coating as received would be determined 
using the manufacturer's data. The volume of each primer and topcoat 
used would be determined using company records. If diluent solvents or 
other ingredients are added to a primer or topcoat prior to 
application, then the total organic HAP and VOC weight fractions, 
density, and volume must be adjusted appropriately to account for such 
additions. These values would be required for each 24-hour period; 
however, only changes in formulation would require re-determination of 
total organic HAP and VOC weight fractions and density.
    The proposed standards would then require the owner or operator to 
calculate the volume-weighted average mass of both VOC and organic HAP 
in coatings emitted per volume of coating (less water and exempt 
solvents for VOC; less water for HAP) as applied. This calculation 
would be performed for each 24-hour period.
    If an owner or operator is seeking to comply by using compliant 
coatings, the owner or operator would need to determine the organic HAP 
content (less water as applied) and VOC content (less water and exempt 
solvents as applied). If no changes in formulation as applied occurred, 
then a re-calculation of the organic HAP and VOC content levels would 
not be required. Where compliant coatings are used, the proposed rule 
would require the determination of the organic HAP content using 
manufacturer's data and VOC content using Method 24 or manufacturer's 
data.
    If a control device is used, the proposed standards require the 
owner or operator to conduct an initial performance test to demonstrate 
compliance with the overall control efficiency requirement of at least 
81 percent. The percent reduction achieved by a control device may be 
determined based either on total organic compounds (TOC) minus methane 
and ethane or on total organic HAP.
    For a carbon adsorber, the overall control efficiency would be 
determined using a mass balance. The mass balance calculation would be 
made every rolling period (the length of the rolling period will vary 
from facility to facility and will range from 1 to 30 days).
    For control devices other than carbon adsorbers, the overall 
control efficiency would be based on capture efficiency and destruction 
efficiency. Capture efficiency would be determined based on the 
procedure specified in Sec. 52.741(a)(4)(iii) of 40 CFR subpart O, 
unless the operation is performed within a total enclosure. An 
enclosure that meets the requirements of a total enclosure as specified 
in Sec. 52.741, appendix B, Procedure T of 40 CFR subpart O would have 
a capture efficiency of 100 percent.
    The destruction efficiency of a control device other than a carbon 
adsorber would be determined using the following methods. Method 1 or 
1A of 40 CFR part 60, appendix A, as appropriate, would be used for 
selection of the sampling sites, and the gas volumetric flow rate would 
be determined using Method 2, 2A, 2C, or 2D of 40 CFR part 60, appendix 
A, as appropriate. Method 18 of 40 CFR part 60, appendix A, would then 
be used to measure either TOC minus methane and ethane or total organic 
HAP at the inlet and outlet of the control device. Also, any other test 
methods or data that have been validated according to the applicable 
procedures in Method 301 of 40 CFR part 63, appendix A, may be used.
    The proposed standards would also allow the use of alternative 
application methods provided that they generate organic HAP and VOC 
emissions less than or equal to the emissions generated by HVLP or 
electrostatic spray guns. The emission levels of the alternative 
application method must be determined under actual production 
conditions. This test would first involve determining the organic HAP 
and VOC emissions for the 90-day period immediately preceding the 
implementation of the alternative application method. During this 
initial 90-day period, only HVLP or electrostatic spray guns would be 
used. The alternative method would then be used on actual production 
parts or assemblies for a period of time sufficient to coat an 
equivalent amount of parts and assemblies as coated in the initial 90-
day period. Coatings used during the test period must be the same as 
those used during the initial 90-day period. In addition, the dried 
film thickness must be equivalent to that applied during the initial 
90-day period.
    The organic HAP and VOC emissions for the period of time where the 
alternative method was used would then be calculated. Where the organic 
HAP and VOC emissions after implementation of the alternative method 
are less than or equal to the emissions for the initial 90-day period, 
the alternative application method is in compliance.
    The South Coast Air Quality Management District (SCAQMD), in 
conjunction with the California Air Resources Board (CARB), is 
currently developing a test protocol to measure the transfer efficiency 
of spray application equipment. This test protocol would represent an 
alternative method of qualifying application equipment for use under 
the proposed standards. Since this test protocol is still under 
development, the EPA is requesting comments from those familiar with 
this test protocol or any other transfer efficiency laboratory test 
method concerning the ability of these procedures to accurately and 
repeatedly measure the transfer efficiency of spray application 
equipment. In addition, the EPA is requesting comments on other methods 
that may be used to measure the transfer efficiency of spray 
application equipment.
    c. Depainting. For the organic HAP emissions portion of the 
proposed standards for depainting, the only test method or procedure 
that would be required is the determination of the organic HAP content 
of each chemical stripper. The proposed standards would require the use 
of information supplied by the manufacturer to determine the organic 
HAP content. If the organic HAP content of the chemical stripper cannot 
be determined from manufacturer's data, then the owner or operator 
would submit an alternative procedure for determining the organic HAP 
content for approval by the Administrator.
    For the annual limit on the gallons of organic HAP-containing 
chemical stripper used for spot stripping and decal removal, the total 
annual volume as applied of organic HAP-containing chemical stripper 
and the number of aircraft depainted would be determined from company 
records. The proposed standards would then require the owner or 
operator to calculate the gallons of organic HAP-containing chemical 
stripper used per aircraft. This calculation would be performed for 
each annual period.
    The proposed standards require inorganic HAP emissions from 
depainting operations to be reduced by 99 percent using particulate 
filters such as baghouses, cartridge filters, or dry filter media. The 
EPA is proposing the use of Method 5 in appendix A to 40 CFR part 60 to 
determine removal efficiency. The proposed standards would require 
retesting whenever the particulate filter or supplier of the filter 
media changes, or whenever modifications are made to the emission 
collection system.
    d. Chemical Milling Maskants. The same basic test methods and 
procedures identified for primer and topcoat application operations are 
also being proposed for chemical milling maskants, requiring the 
determination of total organic HAP weight fraction, density, and volume 
of chemical milling maskants as applied. Simpler procedures are being 
proposed, as for primer and topcoat application operations, to 
demonstrate compliance where only compliant chemical milling maskants 
are being used.
    As for primer and topcoat application operations, any control 
device, including a carbon adsorber, used to control emissions from 
chemical milling maskant application operations must have an overall 
control efficiency of at least 81 percent and must control, except for 
incidental emissions, all of the emissions from the maskant operation. 
Test methods that would be used to determine the overall control 
efficiency are identical to those given previously for primer and 
topcoat application operations.
    e. Handling and storage of waste. No test methods are being 
proposed.
2. Monitoring Requirements
    Monitoring is required by the proposed standards to determine 
whether a source is in continuous compliance. This can be accomplished 
by continuously measuring site-specific operating parameters, the 
values of which are established by the owner or operator during the 
initial compliance test. The operating parameter value is defined as 
the minimum or maximum value established for a control device or 
process parameter that, if achieved by itself or in combination with 
other operating parameter values, determines that an owner or operator 
is complying with the applicable emission limitation or standards. This 
type of enhanced monitoring would be required for those emission points 
for which the standards are expressed as a percent control. In 
addition, the owner or operator is expected to install and operate the 
equipment properly. For owners or operators complying with the proposed 
standards for spray gun cleaning through the use of enclosed spray gun 
cleaners, compliance would be demonstrated through recordkeeping (see 
section II.F).
    The proposed rule would require temperature to be monitored, using 
a continuous recorder, for incinerators. For catalytic incinerators, 
temperature monitors would be placed immediately before and after the 
catalyst bed. For other incinerators, the temperature monitor would be 
placed in the firebox or in the ductwork immediately downstream of the 
firebox and before any substantial heat exchange occurs. All monitoring 
equipment would be installed, calibrated, maintained, and operated 
according to manufacturer's specifications.
    Section 63.6(g) of 40 CFR part 63, subpart A, allows an owner or 
operator of an affected source to request the use of alternative 
methods of emission reduction for complying with design, equipment, 
work practice, or operational emission standards, or combination 
thereof, established under this part.6 Under the proposed rule, an 
owner or operator of an affected source may also use control devices 
other than those specifically identified in the proposed rule as a 
means for achieving compliance with any portion of the rule. If devices 
other than those identified are used, the proposed standards would 
require the owner or operator to submit the parameters to be monitored 
to the Administrator for approval.
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    \6\Ibid.
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    The proposed standards would require each owner or operator to 
establish a range of values for each of these monitored parameters 
during the initial performance test. As long as the control device is 
operated within the established ranges, the proposed emission standards 
are considered to be met. Consequently, exceedances of these parameters 
would be considered a violation of the standards since operating the 
control device outside of the parameters may reduce the efficiency of 
the control device.
    a. Cleaning operations. The proposed rule would require enclosed 
spray gun cleaners to be visually inspected at least once per month for 
leaks. The inspections would occur while the enclosed cleaner is in 
operation.
    b. Primer and topcoat application operations. Where an incinerator 
or other control device is used to control organic HAP and VOC 
emissions from primer and topcoat application operations, the 
monitoring requirements specified above would be required.
    For control of inorganic HAP emissions from primer and topcoat 
application operations, the proposed standards would require that the 
pressure drop across the particulate filters or waterwash be monitored 
on a continuous basis.
    c. Depainting. No monitoring requirements for organic HAP emissions 
are being proposed. For inorganic HAP emissions, continuous monitoring 
of the pressure drop across the filter, as for primers and topcoats, is 
being proposed.
    d. Chemical milling maskant application operations. Where a control 
device is used to control organic HAP and VOC emissions from chemical 
milling maskant application operations, the monitoring requirements 
specified above would be required.
    e. Handling and storage of waste. No monitoring requirements are 
being proposed.

F. Recordkeeping and Reporting Requirements

    The proposed rule proposes to adopt the requirements contained in 
Sec. 63.9 (a) through (e) and Sec. 63.9 (h) through (j) and Sec. 63.10 
(a), (b), (d), and (f) of 40 CFR part 63, subpart A.7 The proposed 
rule, however, contains additional or clarifying elements and changes 
certain time periods allowed for submitting or responding to certain 
reports and requests required in Sec. 63.10. These elements and changes 
are summarized below for each of the operations for which standards are 
being proposed.
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    \7\Ibid.
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1. Recordkeeping Requirements
    a. Cleaning operations. For each cleaning solvent used at the 
facility, the proposed rule would require a record of the name of the 
cleaning solvent and documentation that shows the organic HAP 
constituents of the cleaning solvent. For each cleaning solvent used in 
hand-wipe cleaning operations that conforms to the approved composition 
list, the records that would be maintained are the name of each 
cleaning solvent, documentation demonstrating compliance to the 
approved composition list, and annual purchasing records showing the 
annual volume purchased of each. For each cleaning solvent used in 
hand-wipe cleaning operations that does not conform to the approved 
composition list but does conform to the vapor pressure requirement, 
the information required to be recorded would be the name of each 
cleaning solvent, the monthly usage of the cleaning solvent at each 
operation, the composite vapor pressure, the manufacturer's data sheets 
or other documentation of the vapor pressure, and any test reports and 
calculations performed to determine the composite vapor pressure.
    For cleaning solvents that do not conform to either the composition 
or vapor pressure requirements and are used for the exempt cleaning 
operations, daily records must be maintained of the name and volume of 
each cleaning solvent at each operation at which it is used, and the 
parts, assemblies, or subassemblies cleaned at these operations.
    In addition, a record of all leaks from spray gun cleaners would be 
kept, including source identification, the date that the leak was 
discovered, and the date that the leak was repaired.
    b. Primer and topcoat application operations. For all primers and 
topcoats used at the facility, records must be maintained of the name 
of each primer and topcoat and its organic HAP and VOC content as 
received. In addition, the EPA is proposing different levels of 
recordkeeping requirements depending on how the organic HAP and VOC 
content levels are met. For primers or topcoats that are individually 
compliant with the organic HAP and VOC content limits, records would be 
required of the organic HAP and VOC content as applied, all data, 
calculations, and test results (including Method 24 results taken 
during an enforcement inspection) used in determining the organic HAP 
and VOC contents as applied, and the monthly usage of each coating 
formulation within each coating category.
    If averaging among compliant and non-compliant coatings is used to 
achieve compliance, then the proposed standards would require that up-
to-date records of daily volume-weighted average mass of organic HAP 
and VOC contained in the coatings as applied be maintained. This 
information would include all data and calculations used in determining 
these daily values, such as manufacturer's data certifying the organic 
HAP content of each coating as applied and Method 24 test results 
(including those taken during an enforcement inspection) or 
manufacturer's data that show the VOC content as applied.
    If a control device is used to comply with the organic HAP or VOC 
content limit for primers or topcoats, up-to-date records must be kept 
on the control device. Each owner or operator would be required to keep 
records of the equipment monitoring parameter measurements specified in 
the proposed rule. For an incinerator other than a catalytic 
incinerator, continuous records must be maintained of the firebox 
temperature (or temperature in the ductwork immediately downstream of 
the firebox). For a catalytic incinerator, continuous records must be 
maintained of the gas stream temperature immediately before and after 
the catalyst bed. For both types of incinerators, records must be 
maintained of the overall control efficiency and all test results, 
data, and calculations used in determining the overall control 
efficiency.
    For carbon adsorbers, records must be maintained of the overall 
control efficiency, all test results, data, and calculations used in 
determining the overall control efficiency, and the length of the 
rolling material balance period and all of its supporting data and 
calculations used to determine the rolling period.
    For inorganic HAP emissions from primer and topcoat application 
operations, either particulate filters or waterwash spray booths would 
be used to achieve compliance. Records must be maintained of the 
manufacturer's recommended limits for the pressure drop and readings of 
the pressure drop across the filters or waterwash that are taken once 
each shift during which the coating processes are in operation.
    c. Depainting operation. Each owner or operator of a depainting 
operation would be required to keep up-to-date records of the name of 
each chemical stripper used, the organic HAP content of each stripper 
and its supporting documentation, and the monthly volume usage of each 
chemical stripper that contains organic HAP.
    For non-chemical depainting methods, such as media blasting, owners 
and operators would be required to maintain records of the type of non-
chemical-based equipment used and a description of any malfunctions 
that occur. If a malfunction occurs, the information to be kept would 
be the dates the malfunction occurred and was corrected, the methods 
used to depaint the aerospace vehicles during the malfunction, and the 
dates that these methods were begun and discontinued.
    The proposed standards for depainting contains exemptions for parts 
stripping, spot stripping, and decal removal, each of which requires 
certain records to be maintained. For parts stripping, records must be 
maintained for each model of aerospace vehicle of the parts normally 
removed from the vehicle. For spot stripping and decal removal, annual 
records must be maintained of the number of aircraft stripped, the 
volume of organic HAP-containing chemical stripper used for spot 
stripping and decal removal, the average number of gallons of organic 
HAP-containing stripper used per aircraft, and all supporting data and 
calculations.
    For inorganic HAP emissions from depainting operations, either 
particulate filters or baghouses (equipped with either bag or cartridge 
filter media) would be used to achieve compliance. Records must be 
maintained of the filter manufacturer's recommended pressure drop 
limits and the readings of the pressure drop across the filter taken 
once each shift during which the depainting process is in operation. 
Also, records must be maintained of the particulate control efficiency 
of each filter and all test results, data, and calculations used to 
determine the control efficiency.
    d. Chemical milling maskant application operation. The EPA is 
proposing different levels of recordkeeping requirements depending on 
how the organic HAP and VOC content levels are being met. For chemical 
milling maskants that are individually compliant with the organic HAP 
and VOC content levels, records of the volume-weighted average masses 
of organic HAP and VOC emitted as applied must be kept. In addition, 
all data and calculations used to determine these values and the 
monthly volume of each chemical milling maskant formulation used each 
month must be maintained.
    If averaging among compliant and non-compliant chemical milling 
maskants is used to achieve compliance, then the proposed standards 
would require that up-to-date records of daily volume-weighted average 
mass of organic HAP and VOC contained in the chemical milling maskants 
as applied be maintained. This information would include all data and 
calculations used in determining these daily values, such as 
formulation data and Method 24 test results.
    As for primer and topcoat application operations, if a control 
device is used, up-to-date records must be kept on the control device. 
Each owner or operator would be required to keep records of the 
equipment monitoring parameter measurements specified in the proposed 
rule. For an incinerator other than a catalytic incinerator, continuous 
records must be maintained of the firebox temperature (or temperature 
in the ductwork immediately downstream of the firebox). For a catalytic 
incinerator, continuous records must be maintained of the gas stream 
temperature immediately before and after the catalyst bed. For both 
types of incinerators, records must be maintained of the overall 
control efficiency and all test results, data, and calculations used in 
determining the overall control efficiency.
    For carbon adsorbers, records must be maintained of the overall 
control efficiency, all test results, data, and calculations used in 
determining the overall control efficiency, and the length of the 
rolling material balance period and all of its supporting data and 
calculations used to determine the rolling period.
    e. Handling and storage of waste. Each owner or operator would be 
required under the proposed standards to keep an up-to-date record of 
each waste stream generated at the facility, identification of which 
wastes are subject to RCRA and which are not, and documentation 
supporting those determinations.
2. Reporting Requirements
    The proposed rule would require four basic types of reports: (1) 
Initial notification, (2) notification of compliance status, (3) 
periodic reports, and (4) other reports. In addition, the proposed rule 
would require that the results of any performance test required under 
Sec. 63.7 of the General Provisions to 40 CFR part 63, subpart A, be 
reported no later than 30 days after the completion of the test.8 
A permit application as required under 40 CFR part 70 may be used in 
lieu of the initial notification provided the same information is 
contained in the permit application as required for the initial 
notification.
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    \8\Ibid.
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    As stated above, the proposed standards adopt the reporting 
requirements contained in Sec. 63.9(a) through Sec. 63.9(e) and 
Sec. 63.9(h) through Sec. 63.9(j) and 63.10 (a), (b), (d), and (f) of 
40 CFR part 63, subpart A. However, the time period allowed for the 
Administrator to notify the owner or operator in writing of approval or 
disapproval of the request for an adjustment to a particular time 
period or postmark deadline submitted under Sec. 63.9(i) has been 
changed to within 30 calendar days of receiving sufficient information 
to evaluate the request, rather than 15 calendar days as provided for 
in Sec. 63.9(i)(3).
    Sections 40 CFR 63.9 and 63.10 of the General Provisions identify 
the type of generic information to be included in the initial 
notification, notification of compliance status, and other reports and, 
therefore, this information is not repeated in this preamble. The 
following paragraphs summarize the additional information specific to 
the aerospace rule that should be included in the notification of 
compliance status and the type of information to be included in the 
periodic reports.
    a. Cleaning operation. The notification of compliance status should 
include an identification of each cleaning solvent used at the 
facility, a description of the procedures to be used to ensure that 
bags and containers are kept closed when not in use and that cleaning 
solvents are stored in closed containers, the name of each cleaning 
solvent that does not conform to the approved composition list, and the 
vapor pressure test results of each.
    Specific to spray gun cleaning, the notification of compliance 
status should also contain a detailed description of all methods used 
to clean spray guns and an explanation as to how each cleaning method 
complies with the proposed standards.
    Information to be included in the semiannual report covers all 
noncompliance situations such as using a hand-wipe cleaning solvent 
that does not conform to the approved composition list or vapor 
pressure requirements used in a non-exempt operation. In addition, the 
semiannual report includes information on new cleaning solvents used 
for hand-wipe cleaning in the previous six months, as well as 
previously reported cleaning solvents no longer in use. The information 
to be provided is a list of any new cleaning solvents used in the 
previous six months, a list of new non-HAP cleaning solvents, if any, 
used, and, for new cleaning solvents used in hand-wipe cleaning 
operations, the composite vapor pressure of each.
    If the cleaning operation has been in compliance for the annual 
period, then an annual report would be required occurring every 12 
months from the date of the initial report stating that the cleaning 
operation has been in compliance with the applicable standards.
    b. Primer, topcoat, and chemical milling maskant application 
operations. For primer, topcoat, and chemical milling maskant 
application operations, the notification of compliance status should 
identify the combination of compliant coatings, averaging, and control 
devices that were used to demonstrate that the facility was in 
compliance, and, for control devices, what operating parameters were 
identified for continuous monitoring in order to ensure continuous 
compliance with the proposed standards.
    Owners and operators complying with the organic HAP and VOC content 
levels for primer, topcoat, and chemical milling maskant application 
operations would be required to report each exceedance of the organic 
HAP or VOC content level, as well as any time a primer or topcoat 
application operation was not immediately shut down when the pressure 
drop across the filters or waterwash was out of range. These reports 
would be submitted on a semiannual basis.
    If control devices are used, semiannual reports would be required 
that contain information on all days when the average values of the 
parameters required to be monitored were outside the ranges established 
in the operating permit.
    For incinerators, this would be whenever each 3-hour average 
temperature was below the average temperature established during the 
most recent performance test during which compliance was demonstrated.
    If no exceedances occur, each owner and operator would submit 
annual statements indicating that each affected facility has been in 
compliance. The annual reports for primer and topcoat application 
operations would also identify the number of times, if any, the 
pressure drop limits for each filter or waterwash system were exceeded.
    c. Depainting operation. The notification of compliance status for 
depainting operations should identify each chemical stripper used at 
the facility to depaint aerospace vehicles and the organic HAP content 
of each. Each chemical stripper that contains organic HAP and is used 
for decal removal, depainting of parts, and spot stripping would also 
be identified. In addition, the types of non-chemical depainting 
methods and techniques used at the facility and the manufacturer's 
recommended pressure drop across the filters for the particulate 
removal system, if applicable, would be identified. Finally, each owner 
or operator would be required to describe the depainting methods to be 
used during periods of malfunction of the non-chemical depainting 
methods.
    Information to be included in the semiannual report would include 
the name of any new chemical strippers used during the previous six 
months and the organic HAP content of each. For each chemical stripper 
used for depainting operations that undergoes reformulation, its 
organic HAP content after reformulation would be submitted with the 
semiannual report. The report would also be required if the owner or 
operator used any new non-chemical depainting technique at the facility 
since the initial report or any subsequent semiannual report. The 
semiannual report would be required to identify each 24-hour period 
where organic HAP were emitted from the depainting operation except 
from the exempt operations, any periods of malfunction of non-chemical 
depainting methods and techniques, and any periods where the non-
chemical depainting operation was not immediately shut down when the 
pressure drop across the filters was out of range. For each malfunction 
that occurs, the following information would be reported: (1) The piece 
of equipment that malfunctioned, (2) the date the malfunction occurred 
and the date it was corrected, (3) a description of the malfunction, 
(4) the alternate methods used to depaint the aerospace vehicles during 
the malfunction period, and (5) the dates that these methods were begun 
and discontinued.
    Finally, the semiannual report would be required to identify all 
changes in the type of aircraft depainted at the facility and to 
identify the parts normally removed for depainting separate from the 
aircraft for each new type of aircraft depainted.
    For spot stripping and decal removal, an annual report would be 
required whenever the average volume per aircraft of organic HAP-
containing chemical strippers used exceeds the limits specified in the 
proposed rule for the annual period.
    If the depainting operation has been in compliance for the annual 
period, then an annual report would be required every 12 months from 
the date of the initial report stating that the depainting operation 
has been in compliance with the applicable standards. This annual 
report would also detail how many times the pressure drop limits for 
each filter system were exceeded and report when the calculated annual 
average volume of organic HAP-containing strippers used per aircraft 
for spot stripping and decal removal exceeded the applicable limits.
    d. Handling and storage of waste. The notification of compliance 
status would identify each waste stream and identify whether it is RCRA 
or non-RCRA regulated. The notification would also include a 
description of the procedures to be used to ensure that spills are 
minimized during handling and transfer operations. Also included would 
be the procedures to be used to ensure that waste is stored in closed 
containers.
    Semiannual reports are required to identify any waste stream whose 
RCRA or non-RCRA classification has changed. The semiannual report 
would also identify any new waste streams and whether each is RCRA or 
non-RCRA regulated. An annual report would be required if no changes 
occurred in the RCRA status to the existing waste streams and if no new 
waste streams were generated.

III. Summary of Environmental, Energy, and Economic Impacts of the 
Proposed Standards

A. Emission Reductions

1. Existing Facilities
    For the existing aerospace OEM and rework facilities (approximately 
2,869 facilities in the base year 1991), the nationwide baseline HAP 
emissions are estimated to be 189,000 Mg/yr (208,000 tpy). 
Implementation of the proposed regulation would reduce these emissions 
by approximately 112,600 Mg/yr (123,700 tpy), or 59 percent.
2. New Facilities
    For the aerospace industry, no net growth is expected over the next 
five years; therefore, no net emission reduction due to new facilities 
is anticipated during this period.

B. Secondary Environmental Impacts

    Secondary environmental impacts are considered to be any air, 
water, or solid waste impacts, positive or negative, associated with 
the implementation of the proposed standards. These impacts are 
exclusive of the direct air emission reductions discussed in the 
previous section. All of the impacts discussed below reflect the 
maximum increase or decrease, as appropriate, that would occur if all 
of the affected sources converted to the control option described.
    Some product reformulations that may be used to comply with the 
proposed standards for hand-wipe cleaning, primers, and topcoats may 
contain organic HAP or VOC not present in the original product. In 
these cases, different organic HAP or VOC may be emitted as a result of 
the proposed rule, but the overall level of these compounds that are 
emitted will decrease. Chemical strippers that do not contain organic 
HAP used for depainting may result in increased VOC emissions when used 
to replace methylene chloride-based chemical strippers (methylene 
chloride is a HAP, but not a VOC).
    There is a potential for an impact on water quality resulting from 
some of the prescribed control measures. Under baseline conditions for 
chemical milling maskant operations, no wastewater is generated; 
however, some of the sources may install a carbon adsorber to control 
solvent emissions. If all affected sources use carbon adsorbers, the 
amount of water needed to create regenerating steam for these systems, 
which will add to the wastewater burden from these sources, is 
estimated to be 447 million gallons per year nationwide. For depainting 
operations, there are two options available for meeting the proposed 
rule, both of which will result in a decrease in the amount of 
wastewater generated compared to baseline, which is 251 million gallons 
per year. The decrease in wastewater nationwide is estimated to be 251 
million gallons and 86 million gallons if all affected sources use dry 
media blasting or chemical strippers that do not contain organic HAP, 
respectively.
    Sources installing a carbon adsorption system on their chemical 
milling maskant operations would generate additional solid waste due to 
the necessity of periodically disposing of spent activated carbon. If 
all affected sources use carbon adsorbers, this added nationwide solid 
waste burden is estimated to be 4,500 tons per year, compared to the 
baseline of 21,200 tons per year. Rework facilities that presently use 
a methylene chloride-based paint stripper must dispose of 3,469 tons 
per year of paint/solvent sludge created by depainting. A total 
conversion to dry media paint removal would produce an increase in the 
amount of solid waste composed of dry paint chips and spent blasting 
media. This increase in solid waste is estimated to be 13,280 tons per 
year on a nationwide basis. The proposed standards for the control of 
inorganic HAP emissions from primer and topcoat application operations 
would result in the increase in solid waste generation from the 
disposal of used dry filter media. The increased solid waste burden is 
estimated to be 640 tons per year, compared to the baseline solid waste 
generation of 3,540 tons per year.

C. Energy Impacts

    Some of the control measures proposed for aerospace manufacturing 
and rework operations would lead to increases in energy consumption. 
Both of the control options for chemical milling maskant operations, 
operation of a carbon adsorber or conversion to waterborne chemical 
milling maskant, would involve increased electricity usage (waterborne 
chemical milling maskants must be cured at elevated temperatures). The 
total additional energy needed if all affected sources operate new 
carbon adsorbers is estimated to be 1.7 billion kilowatt-hours (kWh) 
per year, and the energy increase for all affected sources to operate 
new curing ovens for waterborne chemical milling maskants is estimated 
at 324,700 kWh per year. Baseline energy consumption for chemical 
milling maskant operations is considered to be negligible since the use 
of solvent-based chemical milling maskants does not directly require 
the use of electricity.
    The dry media paint removal systems that would be installed at 
rework facilities consume additional energy compared to the solvent 
stripping method. Baseline energy consumption for solvent stripping is 
considered to be negligible since the use of these strippers does not 
directly require the use of electricity. The increase in energy 
consumption involved in operating dry media blasting systems is 
estimated to be 51 million kWh per year. The use of chemical strippers 
that do not contain organic HAP is essentially the same as the baseline 
solvent stripping operation; therefore, no energy impact will result 
from their use.
    The proposed standards for the control of inorganic HAP emissions 
from primer and topcoat application operations would require some 
facilities to install additional spray booths. These spray booths, 
whether equipped with dry filters or waterwash, will increase the 
energy consumption of the affected sources. This increase in energy 
consumption is estimated to be 5.9 million kWh per year, compared to 
the baseline energy consumption of 117.4 million kWh per year.

D. Cost Impacts

    The total capital and annualized control costs (1992 dollars), 
including recovery credits, attributable to compliance with the 
proposed standards have been estimated for both existing and new 
facilities. The following two subsections summarize the results of this 
cost analysis.
1. Existing Facilities
    a. Capital costs. Capital costs would be incurred with the 
implementation of control measures for chemical milling maskants (both 
solvent-based chemical milling maskants with a carbon adsorber and 
waterborne chemical milling maskants), dry media blasting for 
depainting, spray gun cleaning, and control of HAP emissions from 
primer, topcoat, and depainting operations. With the exception of dry 
media blasting for depainting, the nationwide capital costs listed 
below represent the maximum costs that would be incurred assuming that 
all facilities implemented the specific control option. For dry media 
blasting, it is not reasonable to assume that all commercial and 
military rework facilities (a total of 2,026 facilities) depaint the 
outer surface of aerospace vehicles. Therefore, it was assumed that 
only 5 percent of the small and medium size rework facilities and all 
of the large rework facilities perform outer surface depainting.
    For carbon adsorbers used in conjunction with solvent-based 
chemical milling maskants, the nationwide capital cost is estimated to 
be $500 million, and for waterborne chemical milling maskants it is 
estimated to be $289 million. The implementation of dry media blasting 
systems for depainting would require a nationwide capital cost of $61 
million. It should be noted that other control measures exist for 
depainting other than dry media blasting, such as chemical strippers 
that do not contain organic HAP, that require no capital investment. 
Selection of chemical strippers that do not contain organic HAP by all 
affected sources instead of dry media blasting would decrease the total 
nationwide capital investment by approximately 10 percent. The proposed 
rule would also require capital costs for high transfer efficiency 
application equipment and spray gun cleaning equipment totalling $130 
million and $10 million, respectively. The control of inorganic HAP 
emissions from primer and topcoat application operations would require 
the installation of spray booths and filter systems at a capital cost 
of $13 million.
    Total nationwide capital costs range from $503 million to $714 
million, depending on which chemical milling maskant control option is 
used.
    b. Annual costs. All of the control options will result in some 
annual costs being incurred by the affected sources. However, the 
annualized cost figures presented below reflect the net cost to 
implement the control options after taking into account the costs that 
would have been incurred for baseline. This net cost (MACT cost minus 
baseline cost) resulted in net annual savings for primers, topcoats, 
and high transfer efficiency application methods; spray gun cleaning; 
and the use of chemical strippers that do not contain organic HAP. All 
other options resulted in net annual costs to the affected sources. The 
net cost (or savings) for all control options reflects the maximum cost 
(or savings) that would be incurred assuming all affected sources 
implemented the specific control option.
    Only one cost analysis was completed for primers, topcoats, and 
high transfer efficiency application methods due to the 
interrelationship between these operations. For example, high transfer 
efficiency application methods will result in a lower volume of primers 
and topcoats being applied. In addition, the organic HAP and VOC limits 
on primers and topcoats will, due to higher solids content, also result 
in a lower volume of the coatings being applied. The reduction in 
coating usage due to the lower organic HAP and VOC content had to be 
taken into account first, then the reduction in coating usage due to 
high transfer efficiency application methods was applied to this 
reduced coating volume to obtain the true overall reduction in coating 
usage. After factoring in the annualized cost of the coating equipment, 
the analysis showed a nationwide savings of $71 million for commercial 
sources and $18 million for military sources.
    The savings for primers, topcoats, and high transfer efficiency 
application methods are due primarily to labor savings that would 
result from the reduced volume of coatings to be applied. For example, 
if it would have taken 15 gallons of primer under baseline conditions 
to coat an aircraft and only 12 gallons under MACT conditions, then the 
cost analysis assumes a labor savings for the 3 gallons of primer that 
were not applied. The EPA has received some evidence, however, that the 
labor stays the same or may even increase with the use of high transfer 
efficiency application methods (specifically HVLP spray guns). The EPA 
requests comments from facilities that have converted from conventional 
spray guns to HVLP spray guns regarding the labor hours per gallon of 
coating applied for each application method.
    For spray gun cleaning, the proposed standards would result in a 
nationwide savings of approximately $56 million. This is due primarily 
to reduced solvent usage and associated spent solvent disposal.
    The use of chemical strippers that do not contain organic HAP would 
result in a nationwide savings of approximately $2 million. While the 
cost of non-HAP strippers is generally higher than the cost of 
conventional strippers, this cost is offset by the reduced disposal 
costs incurred with non-HAP strippers. Since non-HAP strippers do not 
contain methylene chloride, they can typically be treated on-site. This 
eliminates the disposal costs incurred with the conventional strippers, 
which are typically shipped off-site for disposal.
    Nationwide annual costs are estimated to be $14 million for hand-
wipe and flush cleaning, $111 million for waterborne chemical milling 
maskants, $2 million for inorganic HAP emissions from primer and 
topcoat application operations, and $0.3 million for inorganic HAP 
emissions from blast depainting operations.
    Total nationwide costs, taking into account both the savings and 
costs detailed above, are estimated to be a savings of $20 million.
    Sources subject to the proposed rule would be required to perform 
certain monitoring, recordkeeping, and reporting tasks. These 
information collection requirements will create a burden on the 
affected sources in terms of resources needed to comply with these 
requirements (see section VI.D.). The total nationwide costs of the 
manpower requirements to complete these tasks are estimated to be $36.7 
million.
    Total nationwide costs are estimated to be $16.7 million, which is 
the sum of the annualized costs (a total nationwide savings of $20 
million) and the costs due to monitoring, recordkeeping, and reporting 
requirements (a total nationwide cost of $36.7 million).
2. New Facilities
    For the aerospace industry, no net growth is expected over the next 
five years; therefore, no net costs (or savings) due to new facilities 
are anticipated during this period.

E. Economic Impacts

    Due to the low total compliance costs associated with the proposed 
regulation, the discussion of the economic impacts is presented in a 
qualitative manner. The low costs of the proposed regulation are in a 
large part due to cost savings expected to be achieved by some model 
plants. The economic impact analysis discussed in a qualitative manner 
the primary impacts (the direction of price and output changes in the 
aerospace industry), as well as secondary impacts (the direction of 
changes in the demands for inputs such as coatings) associated with the 
proposed regulation.
    Cost estimates indicate that the total annual compliance costs are 
approximately $16.7 million. In 1990, revenue for this industry 
equalled approximately $118.9 billion. Using revenue data as a proxy 
for production costs, the costs of the proposed regulation are only 
0.01 percent of the total production costs for the industry. This 
increase in production cost is expected to have minimal impact on the 
current prices and outputs of the aerospace industry.
    Secondary impacts refer to changes in factor demand by all 
aerospace producers. For example, while the primary impact of the 
regulation on spray gun cleaning is a decrease in the cost of 
performing this task, the actual cause of the decrease in the cost is a 
reduction in the use of methyl ethyl ketone and other solvents. 
Although compliance with the proposed regulation is expected to reduce 
consumption of coatings and solvents in general and, therefore, 
negatively impact the producers of these products, compliance with the 
proposed regulation is also expected to increase product substitution 
so that demand for non-HAP strippers, waterborne maskants, and low 
vapor pressure solvents will increase. Lack of economic data on a 
product-specific basis prevents quantification of the indicated 
impacts.

IV. Process Descriptions and Control Technologies

A. Process Descriptions

    Aerospace manufacturing and rework operations consist of the 
following basic operations: Chemical milling maskant application, 
chemical milling, adhesive bonding, cleaning (e.g., hand-wipe, spray 
equipment, and flush), metal finishing, electrodeposition, coating 
application (e.g., primers, topcoats, sealants, and specialty 
coatings), depainting, and composite processing. In addition, most 
aerospace manufacturing and rework facilities generate waste and 
wastewater, and some facilities have storage tanks for hand-wipe 
cleaning solvents. An aerospace facility may conduct all of these 
processes in its operations, such as an OEM facility that produces the 
entire aircraft. However, an aerospace facility may conduct only a 
subset of these operations, such as a facility that produces a single 
component or assembly, or a facility that provides a service such as 
chemical milling.
1. Chemical Milling Maskant Application and Chemical Milling
    Chemical milling uses etchant solutions to reduce the thickness of 
selected areas of metal parts in order to reduce weight. The process is 
typically used when the size or shape of the part precludes mechanical 
milling or when chemical milling is advantageous due to shorter 
processing time or its batch capability.
    Chemical milling maskants are typically rubber- or polymeric-based 
coatings applied to an entire part or subassembly by brushing, dipping, 
spraying, or flow coating. After the chemical milling maskant is cured, 
it is removed from selected areas of the part where metal is to be 
removed during the chemical milling process. The chemical milling 
maskant remaining on the part protects those areas from the etchant 
solution. Chemical milling maskants typically contain either a toluene/
xylene mixture or perchloroethylene as its solvent constituents.
    Organic HAP emissions occur through evaporation of the solvent as 
the chemical milling maskant is applied and while it cures.
2. Adhesive Bonding (Adhesives and Adhesive Bonding Primers)
    Adhesive bonding involves the joining together of two or more metal 
parts, such as the parts of a honeycomb core. This process is typically 
performed when the joints being formed are essential to the structural 
integrity of the aircraft. The surfaces to be bonded are first coated 
with an adhesive bonding primer to promote adhesion and protect from 
subsequent corrosion. Structural adhesives are applied as either a thin 
film or as a paste, and can be oven cured or cured in an autoclave. 
Organic HAP emissions occur from the evaporation of solvents contained 
in the adhesive bonding primer and adhesive during their application, 
as well as during the curing step.
3. Cleaning Operations
    a. Hand-wipe and flush cleaning. Aerospace components are cleaned 
frequently during manufacturing to remove contaminants such as dirt, 
grease, and oil, and to prepare the components for the next operation. 
Cleaning is typically performed by a hand wiping process using a wide 
variety of cleaning solvents. Assemblies and parts with concealed or 
inaccessible areas may be flush cleaned by pouring the cleaning solvent 
over or into the part. The cleaning solvent is then drained from the 
part and the procedure is repeated as many times as necessary to ensure 
the required cleanliness.
    Organic HAP emissions from hand-wipe and flush cleaning operations 
occur from the evaporation of cleaning solvents during the cleaning 
process, including evaporation of the solvent from open containers and 
from solvent-soaked cloth and paper. Organic HAP emissions also occur 
from storage tanks used to store cleaning solvents.
    b. Spray gun cleaning. Spray guns and other components of coating 
units must be cleaned when switching from one coating to another and 
when they are not going to be immediately reused. The cleaning of spray 
guns can be performed either manually or with enclosed spray gun 
cleaners. Manual cleaning involves disassembling the gun and placing 
the parts in a vat containing an appropriate cleaning solvent. The 
residual paint is brushed or wiped off the parts. After reassembling, 
the cleaning solvent may be sprayed through the gun for a final 
cleaning.
    Enclosed spray gun cleaners are self-contained units that pump the 
cleaning solvent through the gun within a closed chamber. After the 
cleaning cycle is complete, the guns are removed from the chamber and 
typically undergo some manual cleaning to remove coating residue from 
areas not exposed to the cleaning solvent, such as the seals under the 
atomizing cap.
    Organic HAP emissions from spray gun cleaning occur from the 
evaporation of cleaning solvents during the cleaning cycle, such as 
while hand cleaning the guns in an open vat. Organic HAP emissions also 
occur from enclosed spray gun cleaners when they are opened to remove 
the guns.
4. Metal Finishing and Electrodeposition
    Metal finishing processes are used to prepare the surface of a part 
for better adhesion, improved surface hardness, and improved corrosion 
resistance. Typical metal finishing operations include conversion 
coating, anodizing, desmutting, descaling, and any operation that 
chemically affects the surface layer of a part.
    Electrodeposition, or metal plating, is an additive process for 
metal substrates in which another metal layer is added to the substrate 
in order to enhance corrosion and wear resistance necessary for the 
successful performance of the component. The two types of 
electrodeposition typically used are electroplating and plasma arc 
spraying.
    HAP emissions from metal finishing operations occur in the form of 
gases or vapors that evaporate from the surface of processing 
solutions. Evaporation of solution also occurs from the parts as they 
are removed from the processing tanks.
5. Coating Application
    A coating is a material that is applied to the surface of a part to 
form a decorative or functional solid film. The most common coatings 
are the broad categories of non-specialized primers and topcoats. There 
are also numerous specialty coatings ranging from temporary protective 
coatings to radiation effect coatings designed to shield aircraft from 
radar detection.
    Coatings are applied to aerospace vehicles and components using 
several methods of application. The methods most commonly used are 
spraying, brushing, rolling, flow coating, and dipping. Spray 
application systems include conventional air spray, airless spray, air-
assisted airless, electrostatic, and high volume low pressure (HVLP) 
spray. These latter two methods are generally accepted as having better 
transfer efficiency than other spraying methods and are gaining 
increased use as a means of using less coating and, hence, reducing 
emissions.
    Nearly all aerospace coatings contain a mixture of organic 
solvents. Organic HAP emissions from coating application occur from the 
evaporation of the solvents during mixing, application, and drying. 
Inorganic HAP emissions of metal compounds (e.g., chromium and cadmium) 
also occur from overspray, which is exhausted from spray booths or 
paint spray hangars.
6. Depainting
    The depainting operation involves the removal of coatings from the 
outer surface of aircraft. The two basic depainting methods are 
chemical depainting and blast depainting. Chemical depainting agents 
are applied to the aircraft, allowed to degrade the coating, and then 
scraped or washed off with the coating residue. Blast depainting 
methods utilize a media such as plastic, wheat starch, carbon dioxide, 
or high pressure water to remove coatings by physically abrading the 
coatings from the surface of the aircraft.
    Organic HAP emissions from chemical depainting occur from 
evaporation of the solvents in the stripping solution. The amount of 
emissions from the process is directly related to the surface area 
being stripped, the type and thickness of coating to be removed, and 
the effectiveness of the stripper. Inorganic HAP emissions occur from 
the various blast depainting methods. The inorganic HAP are contained 
in the coatings being removed (trace amounts of inorganic HAP may also 
be found in some blast media) and are emitted as particulates.
7. Composite Processing
    Composite processing consists of seven basic operations: Layup, 
thermal forming, debulking, curing, break-out, compression molding, and 
injection molding. Layup is the process of assembling the layers of the 
composite structure by positioning composite material in a mold and 
impregnating the material with a resin. Thermal forming is the process 
of forming the layup in a mold, which usually takes place in an 
autoclave. During the thermal forming process, debulking also may 
occur, which is the simultaneous application of low-level heat and 
pressure to the composite structure to force out excess resin, trapped 
air, vapor, and volatiles from between the layers of the composite 
structure. The curing step, which is the process of changing the resin 
into a solid material through a polymerization reaction, also occurs in 
the autoclave. After curing and removal from the autoclave, the break-
out process removes the composite structure from the molds or curing 
fixtures.
    Two other methods of forming composite structures are compression 
molding and injection molding. Compression molding is the process of 
filling one half of a mold with a molding compound, closing the mold, 
and applying heat and pressure until the material is cured. Injection 
molding uses a closed mold, where the molding compound is injected into 
the mold, maintained under pressure, and then cured by applying heat.
    Organic HAP emissions from composite processing occur from 
volatilization of a small portion of the solvent components during 
curing, because the majority of these solvents are consumed in the 
curing reaction of the resin.
8. Wastewater
    Nearly every aerospace manufacturing and rework operation has the 
potential to generate wastewater. For example, metal finishing 
operations use water to rinse parts after each processing step. These 
rinse steps are typically carried out in large tanks with either a 
continuous or intermittent water flow. The wastewater generated is 
usually treated to some extent at the facility, then discharged.
    HAP emissions from wastewater result from the evaporation of 
volatile components in the water. Evaporation may occur in open 
trenches, storage tanks, and treatment operations.
9. Handling and Storage of Waste
    Waste is produced primarily from cleaning, coating, and depainting 
operations. Cleaning operations produce solvent laden cloth and paper 
and spent solvent which can emit organic HAP from the evaporation of 
the solvents. Coating operations produce waste paint and waste solvent 
thinner that also emit organic HAP through evaporation. Depainting 
operations can produce either a liquid or solid waste stream depending 
on the type of process used. Chemical depainting processes produce a 
liquid sludge that consists of the stripper solution and paint residue. 
Emissions occur from the evaporation of the solvent from the stripper 
solution. Blast depainting processes produce a solid waste stream that 
consists of paint chips and spent blasting media. Emissions do not 
directly occur from this waste stream, although particulate emissions 
are generated during the blasting process.
10. Storage of Hand-Wipe Cleaning Solvents
    Many large aerospace facilities use storage tanks for hand-wipe 
cleaning solvents. According to data obtained through responses to EPA 
questionnaires under section 114 of the Act (section 114 
questionnaires), these tanks are primarily above ground, fixed-roof 
type ranging in size from 350 to 6800 gallons in size. Emissions from 
these tanks occur from evaporation of the cleaning solvents, as well as 
breathing and working losses.

B. Control Techniques

    The principal techniques used by the aerospace industry to control 
organic HAP emissions are preventative measures and control devices. 
For the control of inorganic emissions, control devices such as filters 
and waterwash are used. Preventative measures are any action, product 
modification, process modification, or equipment change designed to 
eliminate or reduce the generation of emissions. Control devices do not 
prevent the generation of emissions, but rather capture or destroy the 
emissions generated by a source.
    Preventative measures are usually the most desirable method to 
reduce emissions since they eliminate or reduce the actual generation 
of pollutants. Typically, the emission reduction is obtained using less 
energy and producing less waste than using a control device to achieve 
the same emission reductions. Preventative measures used by the 
industry are: (1) Product reformulations that replace products 
containing high levels of HAP and VOC with products containing less HAP 
and VOC or that eliminate the HAP or VOC content completely, such as 
chemical strippers that contain no organic HAP for depainting; (2) 
product reformulations, such as higher solids content coatings, that 
reduce the amount of the HAP- and VOC-containing product used; (3) 
equipment changes that result in emission reductions, such as replacing 
conventional spray guns with HVLP spray guns; and (4) work practice 
standards, such as housekeeping.
    Control devices are typically used where product reformulation is 
not feasible or where the concentration of the exhaust stream is 
sufficiently high to warrant their use. Control devices may destroy the 
HAP and VOC, as with an incinerator, or capture the HAP and VOC, as 
with a carbon adsorber. Often, the compounds captured by a control 
device can be recovered for reuse. Control devices in predominant use 
by the industry for the reduction of organic HAP emissions are: (1) 
Carbon adsorbers, (2) incinerators, and (3) ultraviolet oxidation. 
Activated carbon fiber adsorbents to concentrate VOC emissions are 
frequently used in conjunction with incinerators. For inorganic HAP 
particulate emissions, reduction is achieved predominantly through the 
use of filtration devices.
1. Preventative Measures
    a. Product reformulation. HAP and VOC emissions may be controlled 
by replacing products containing high concentrations of HAP and VOC 
with ones that have reduced or eliminated HAP and VOC entirely. Each 
individual facility must evaluate the ability of the new product to 
maintain standards of quality and performance. In addition, the 
potential overall environmental benefit of the reformulated products 
must be carefully evaluated.
    (1) Product reformulation--coatings. Product reformulations for 
coatings can be generally classified as waterborne, higher solids, 
powder, and self-priming topcoats. Each category is discussed below.
    (a) Waterborne coatings. Waterborne coatings utilize a resin system 
that is dispersible in water. A portion of the organic solvent is then 
replaced with water. The organic solvent may be 5 to 40 percent by 
weight of the waterborne coating, compared to a conventional organic 
solvent-based coating containing as much as 80 percent by weight 
solvent.
    In addition to the lower solvent content, waterborne coatings have 
other advantages over solvent-based coatings. Less overspray and 
improved spray transfer efficiency may be achieved with waterborne 
coatings than with conventional coatings that utilize solvents with a 
density less than that of water. Additionally, because of the reduced 
solvent content, waterborne coatings may be less toxic and present a 
reduced fire hazard.
    Waterborne coatings have limitations such as requiring spray guns 
with specific materials of construction, protection from freezing, and 
better control of temperature and humidity during application. In 
addition, waterborne coatings generally require longer drying times, 
are more sensitive to substrate material and cleanliness, and have 
lower salt spray resistance.
    (b) Higher solids. Higher solids coatings are solvent-based coating 
formulations that have been modified to lower the solvent-to-solids 
ratio. The coatings usually contain 50 to 65 percent by volume solids, 
compared to conventional solvent-based coatings that may contain up to 
40 percent by volume solids. The increased solids content gives greater 
surface area coverage per gallon of coating, which reduces the total 
volume of coating required. Consequently, solvent emissions are also 
reduced when higher solids coatings are used to apply the same volume 
of solids that are applied with a conventional solvent-based coating.
    Higher solids coatings generally have higher viscosities and longer 
drying times than conventional solvent-based coatings. The higher 
viscosity tends to make spray application more difficult because it is 
harder to control gloss and film thickness, and may require the coating 
to be heated before application. Higher solids coatings typically are 
not used as dip coatings due to the difficulty in maintaining a uniform 
dispersion of solids in the dip tank.
    (c) Powder. Powder coatings are a class of coatings applied 
electrostatically in dry form and then baked to cure. The coatings 
consist of fine, dry particles of paint solids. During the curing step, 
the particles fuse to create a continuous film. Use of powder coatings 
requires that the substrate must be able to withstand the high 
temperatures (typically greater than 121  deg.C (250  deg.F) and 
frequently greater than 177  deg.C (350  deg.F)) necessary to cure the 
paint.
    The major advantage of using powder coatings is greatly reduced 
solvent emissions. The lack of a solvent base also reduces fire hazard, 
toxicity, and the make-up air requirements of the spray booth.
    Powder coatings must be applied electrostatically, so they cannot 
be used on non-conductive parts such as composites. Other reported 
disadvantages of powder coatings are the difficulty in obtaining a high 
quality appearance, production must be shut down for color changes, the 
powder must remain dry at all times prior to application, and higher 
energy costs. As noted above, the high curing temperatures of powder 
coatings precludes their use on temperature-sensitive substrates.
    (d) Self-priming topcoats. Self-priming topcoats eliminate the need 
to apply a primer coat between the substrate and the topcoat. Self-
priming topcoats have the adhesion and corrosion characteristics of a 
conventional primer and the environmental resistance and functional 
fluid resistance of a conventional topcoat. These coatings also 
eliminate the need for chrome-containing primers.
    (2) Product reformulation--hand-wipe cleaning solvents. Product 
reformulations for hand-wipe cleaning that are prevalent in the 
aerospace industry can be classified as aqueous, hydrocarbon-based, and 
non-chemical. Each category is discussed below:
    (a) Aqueous. Aqueous cleaners contain at least 80 percent water, 
are non-flammable and non-combustible, and are completely soluble in 
water. Other components may include corrosion inhibitors, alkalinity 
builders, organic surfactants, and bioenzyme mixtures and nutrients 
depending on the desired soil removal properties. Aqueous cleaners have 
been used in non-critical areas where strict cleanliness requirements 
do not have to be met, or where there are no confined spaces that may 
trap residues of the cleaner.
    (b) Hydrocarbon-Based. Hydrocarbon-based cleaners are nonsemi-
aqueous cleaners that are composed of a mixture of hydrocarbons and 
oxygenated hydrocarbons. These cleaners have a maximum vapor pressure 
of 7 mm Hg at 20  deg.C (3.75 in. H2O at 68  deg.F) and contain no 
HAP or ozone depleting compounds.
    (c) Non-chemical. Several aerospace facilities have demonstrated 
the viability of using non-chemical methods such as dry media blasting 
for cleaning operations. These methods are typically used to remove 
dry, scale-like deposits such as carbon residue on engine components. 
Dry media blasting can usually be used only on components that can 
withstand the force of blasting without deformation.
    b. Equipment changes. The aerospace industry has implemented 
several equipment changes that directly reduce the level of HAP 
emissions. While there are equipment changes that affect emissions from 
every process, the three changes predominantly used in the industry are 
high transfer efficiency spray guns, enclosed spray gun cleaners, and 
proportional paint mixers. Each of these equipment changes are 
discussed below.
    (1) High transfer efficiency spray guns. Emissions from spray 
coating operations can be reduced through the use of spraying systems 
with higher transfer efficiency than conventional spray guns. Transfer 
efficiency, expressed as a percentage, can be defined as the ratio of 
coating solids actually applied to the surface of the component being 
coated to the amount of solids released from the spray gun. Spraying 
systems with a higher transfer efficiency can coat the same surface 
area using less coating. Therefore, the HAP emissions resulting from 
the use of this equipment are reduced compared to applying the same 
coating with conventional spray equipment.
    High volume low pressure (HVLP) and electrostatic spraying systems 
are the primary high efficiency spray methods used by the industry. 
HVLP spray guns use high volumes (10 to 25 standard cubic feet per 
minute (scfm)) of low pressure (2 to 10 pounds per square inch gauge 
(psig)) air to deliver the paint. The lower air pressure creates a 
lower particle speed, resulting in a more controlled spray pattern with 
less overspray and bounce back from the substrate. With electrostatic 
spray systems, atomized particles of coating acquire an electric charge 
as they pass through a high voltage field at the end of the spray 
nozzle. This electric charge causes the particles to be attracted to 
the parts being painted, which are electrically grounded.
    (2) Enclosed spray gun cleaners. Spray guns are typically cleaned 
at the end of every job, as well as between color changes. Manual 
cleaning of spray guns involves disassembling the gun and placing the 
parts in a tray containing an appropriate cleaning solvent. The 
residual paint is brushed or wiped off the parts, then the cleaning 
solvent is sprayed through the gun after it is reassembled. Enclosed 
spray gun cleaners, however, are completely enclosed units that spray 
the cleaning solvent through and over the spray gun. The enclosed unit 
eliminates most of the exposure of the cleaning solvent to the air, 
thereby greatly reducing the organic HAP emissions from evaporation.
    (3) Proportional paint mixers. The majority of coatings used in the 
aerospace industry are multi-component mixtures, consisting of a base 
component and one or more catalyst components. The components must be 
thoroughly mixed in the proper ratio immediately before application. 
When this mixing is performed manually, a greater volume of coating is 
mixed than will actually be used to ensure that there is enough coating 
available to complete the job. In contrast, proportional paint mixers 
pump each component of the coating directly to the spray gun, where it 
is mixed and immediately applied. This results in reduced coating waste 
and, consequently, reduced emissions.
    c. Work practice standards. Work practice standards are changes in 
the method of operation that do not affect the products used in the 
process or the process itself, but result in a reduction in emissions. 
The aerospace industry has implemented work practice standards programs 
for housekeeping measures and managed chemical distribution systems.
    Emissions of organic HAP compounds, particularly solvents, can be 
reduced by limiting both the amount of the material exposed to the 
atmosphere and the length of the exposure. The emission reductions can 
be achieved by implementing housekeeping measures whereby solvent-
soaked cloth or paper used for hand-wipe cleaning are placed into bags 
or containers that are kept closed. This eliminates the continual 
evaporation of the solvent from the cloth or paper when they are not in 
use. The bags or containers can then be collected and disposed in such 
a manner (e.g., by incineration) to eliminate any further solvent 
emissions.
    Managed chemical distribution systems centralize the distribution 
of solvents and coatings and control the amount of these materials 
allowed to be used for a particular task. In this way, waste solvent 
and coatings are reduced, and emissions from these waste materials are 
reduced.
2. Control Devices
    a. Carbon adsorbers. Adsorption systems are used to remove organic 
compounds from gas streams when strict limits on the outlet 
concentration must be met, or when recovery of the compound is desired. 
Adsorption is effective on inlet concentrations ranging from a few 
parts per billion to several thousand parts per million, and a flow 
rate of several hundred to several hundred thousand cubic feet per 
minute. Carbon adsorbers typically have a removal efficiency of 95 to 
99 percent.
    Once the carbon reaches saturation, it can be removed from the 
adsorber vessel and disposed or regenerated. The carbon can also be 
regenerated with steam within the adsorber vessel. This option readily 
allows for the recovery of the organic compounds for recycling.
    b. Incinerators. Two basic types of incinerators, thermal and 
catalytic, are used in the aerospace industry to remove organic 
contaminants. Each type is discussed below.
    (1) Thermal incinerators. Thermal incinerators can be generally 
used on air streams with a wide concentration range of organics. These 
control devices have minimal dependence on the characteristics of the 
organic contaminants, so they can be used to control a wide variety of 
emission streams. Thermal incinerators can achieve removal efficiencies 
of 98 percent and higher.
    The basic operation of thermal incinerators involves raising the 
inlet air stream to the incineration temperature of the contaminants 
and maintaining the temperature for a specific residence time. The 
waste heat content of the incinerator exhaust stream is used to preheat 
the inlet air stream. An auxiliary fuel is then typically required to 
raise the air stream temperature to the incineration temperature.
    (2) Catalytic incinerators. Catalytic incinerators are similar to 
thermal incinerators except that they use a catalyst (a substance that 
accelerates the rate of oxidation without undergoing a chemical change 
itself) to assist in the oxidation of organic compounds to carbon 
dioxide and water. These incinerators are typically used for air 
streams with a low concentration of organics. The removal efficiency of 
catalytic incinerators can be as high as 98 percent.
    c. Ultraviolet oxidation. An ultraviolet light oxidation (UVOX) 
system has been developed as an abatement device for air streams with 
low concentrations of organic compounds. The air stream passes through 
particulate filters, then enters a reactor where it is exposed to 
ultraviolet light which initiates the oxidation of the organics. Ozone 
and other oxygen-based oxidants are injected into the reactor to react 
with the organics in the air stream to begin the oxidation of organics 
into carbon dioxide and water. A typical removal efficiency for UVOX is 
reported to be 95 percent.
    d. Activated carbon fiber adsorbent. Another technology has been 
developed to control low concentration organic compound emissions 
(e.g., paint spray booths). This technology utilizes an activated 
carbon fiber adsorbent to initially capture the organic emissions, the 
concentration of which is too low to be removed by a control device 
such as an incinerator. The adsorbent system consists of a honeycomb 
structure element made of activated carbon fiber paper in corrugated 
form. This structure adsorbs the organics in the exhaust stream. As the 
activated carbon structure becomes saturated, the organics are desorbed 
using hot air. This concentrated air stream can then be sent to an 
incinerator or other control device. The portion of the activated 
carbon structure that was regenerated then begins the adsorption cycle 
again.
    e. Catalyst-coated filter media. Low concentration organic 
emissions (e.g., paint spray booths) can be controlled through the use 
of a catalyst-coated filter media. The catalyst material is impregnated 
onto the fibers of a dry filter which can then be used wherever 
conventional dry filters are used. The catalyst material, unlike 
activated carbon, permanently binds the organic material into its 
crystalline matrix so that it will not later desorb. In addition to the 
coated filters, the catalyst material can be used in a granular form to 
control emissions.
    f. Filtration systems for inorganic HAP particulate emissions. 
Coating operations and blast depainting operations emit inorganic HAP 
in the form of particulates. For coating operations, panel-type dry 
particulate filters and waterwash spray booths are used to control 
these emissions. For blast depainting operations, panel-type dry 
particulate filters are also used, as well as baghouses.
    The dry filters and baghouses capture particulates by trapping them 
as they try to pass through the small passages in the filter media. The 
efficiency of the filter media is a function of the particle size, size 
of the passages in the filter media, air flow through and pressure drop 
across the filter media, and physical characteristics of the particle.
    Waterwash spray booths capture particles by forcing the air stream 
to pass through a spray or curtain of water. The particles are trapped 
by the water and eventually collect as a sludge in the sump of the 
spray booth.

V. Rationale for the Proposed Rule

A. Regulatory Development Process for NESHAP

    During development of a NESHAP, the EPA collects information about 
the industry, including information on emission source characteristics, 
control technologies, data from HAP emission tests at well-controlled 
facilities, and information on the cost, energy, and other 
environmental impacts of emission control techniques. The EPA uses this 
information in the development of possible regulatory approaches.
    If the source category contains major sources, then a MACT standard 
is required. Section 112(d)(3) of the Act defines the minimum 
stringency requirements of the MACT standard for new and existing 
sources. This level of control is referred to as the MACT ``floor,'' 
which needs to be determined as a starting point for developing the 
regulatory alternatives.
    Once the floor has been determined for new and existing sources for 
a category or subcategory, the Administrator must set MACT standards 
that are no less stringent than the floor level. Such standards must 
then be met by all sources within the category or subcategory. However, 
in establishing standards, the Administrator may distinguish among 
classes, types, and sizes of sources within a category or subcategory 
(section 112(d)(1) of the Act). Thus, for example, the Administrator 
could establish two classes of sources within a category or subcategory 
based on size and establish a different emission standard for each 
class as long as each standard is at least as stringent as the floor. 
The Act also contains provisions for regulating area sources. However, 
except for certain recordkeeping requirements contained in the General 
Provisions, these are not relevant to the proposed standards for 
aerospace sources, which apply only to major sources.
    The next step in establishing a MACT standard is the development 
and analysis of regulatory alternatives. First, information about the 
industry is analyzed to develop model plant populations for projecting 
national impacts, including HAP emission reduction levels, costs, and 
energy and secondary environmental impacts. Several regulatory 
alternatives (which may be different levels of emission control, 
different applicability criteria, or both, and one of which is the MACT 
floor) are then evaluated to determine the most appropriate regulatory 
alternative to reflect the MACT level.
    In addition, although NESHAP are normally structured in terms of 
numerical emission limits, alternative approaches are sometimes 
necessary. Section 112(h) of the Act provides that if it is not 
feasible to prescribe or enforce an emission standard, then a design, 
equipment, work practice, or operational standard may be established. 
For example, in some cases source testing may be impossible or at least 
not practicable due to technological and economic limitations.
    In the EPA's decision-making process, the regulatory alternatives 
considered for new versus existing sources may be different and each 
alternative must be technically achievable. In selecting a regulatory 
alternative to represent MACT, the EPA considers the achievable 
reduction in HAP emissions (and possibly other pollutants that are co-
controlled), the cost of control, and economic, energy, and other 
nonair quality health and environmental impacts. The overall objective 
is the achievement of the maximum degree of emission reduction without 
unreasonable economic or other impacts.
    The selected regulatory alternative is then translated into a 
proposed regulation. The regulation implementing the MACT decision 
typically includes sections addressing applicability, standards, test 
methods and compliance demonstration, monitoring, reporting, and 
recordkeeping. The preamble to the proposed regulation, published in 
the Federal Register, provides an explanation of the rationale for the 
decision. The public is invited to comment on the proposed regulation 
during the public comment period. Following an evaluation of these 
comments, the EPA reaches a decision and promulgates the final 
standards.

B. Determining Maximum Achievable Control Technology (MACT) ``Floors''

    Once the EPA has identified the specific major source categories or 
subcategories that it intends to regulate under section 112, MACT 
standards are set at a level at least as stringent as the ``floor.'' 
Congress has provided directives to guide the EPA in the process of 
determining the regulatory floor.
    Congress specified that the EPA must establish standards which 
require ``the maximum degree of reduction in emissions of the hazardous 
air pollutants * * * that the Administrator * * * determines is 
achievable * * *'' (section 112(d)(2) of the Act). In addition, 
Congress limited the Agency's discretion by defining the minimum 
baseline (floor) at which standards may be set, as follows:
    (1) For new sources, the standards for a source category or 
subcategory ``shall not be less stringent than the emission control 
that is achieved in practice by the best controlled similar source, as 
determined by the Administrator,'' and
    (2) For existing sources, the standards ``may be less stringent 
than standards for new sources * * * but shall not be less stringent, 
and may be more stringent than: (A) the average emission limitation 
achieved by the best performing 12 percent of the existing sources (for 
which the Administrator has emissions information) * * * or (B) the 
average emission limitation achieved by the best performing 5 sources * 
* * for categories or subcategories * * * with fewer than 30 sources'' 
(section 112(d)(3)of the Act).

C. Selection of Pollutants and Source Category(ies)

    Section 112(b) of the Act lists the HAP to be regulated with 
standards established under section 112. Section 112(d), as amended, 
requires the EPA to promulgate emission standards for each category or 
subcategory of major sources and area sources of the HAP listed in 
section 112(b). For the purpose of developing these standards, the EPA 
may distinguish among classes, types, and sizes of sources within a 
category or subcategory. The NESHAP are to be developed to control HAP 
emissions from both new and existing sources pursuant to section 112(c) 
of the Act.
    The initial source category list (57 FR 31576, July 16, 1992), 
required by section 112(c) of the Act, identifies source categories for 
which NESHAP are to be established. This list includes all major source 
categories of HAP known to the EPA at this time, and all area source 
categories for which a finding of adverse effects warranting regulation 
has been made.
    The source category list identifies ``surface coating processes--
aerospace industries'' as a source category because it contains major 
sources emitting at least 10 tons of any one HAP or more than 25 tons 
of any combination of HAP annually.
    The aerospace industry encompasses original equipment manufacturers 
of commercial, civil, and military (including space) aerospace 
vehicles. In addition, rework facilities, which repair and repaint 
aerospace vehicles, constitute a major portion of the industry. There 
are also many subcontractors providing support to the industry, 
especially to the OEM's, who subcontract out various portions of the 
work. These subcontractors may engage in many of the processes found at 
OEM or rework facilities, or in just a few. Further, subcontractors may 
conduct operations for non-aerospace industries at facilities at which 
they conduct aerospace operations.
    For the purposes of this rule, the EPA has defined the source 
category as consisting of all facilities engaged in the manufacture or 
rework of any aerospace vehicle or component. This includes all OEM's, 
rework facilities, and subcontractors. The EPA decided to include 
subcontractors in the proposed rule because they perform substantial 
amounts of work, much of which could otherwise be carried out at an OEM 
or rework facility and which is virtually indistinguishable from 
processes at the OEM or rework facility. However, if the 
subcontractors' facilities are not major sources, they would not be 
subject to the proposed standards.
    Early in the development of the proposed standards, the EPA 
developed model plants to correspond to the basic structure of the 
industry--commercial and military segments, each having OEM and rework 
facilities--with the intent of developing subcategories for standards 
development, if necessary. On the basis of the information provided, 
however, the EPA has found that, with one exception for depainting 
operations, there is no need to distinguish among these segments for 
the processes for which standards are being proposed under the proposed 
rule.

D. Selection of Emission Points Covered by the Proposed Rule

    The proposed rule would limit organic HAP emissions from the 
following basic aerospace operations: cleaning, primer application, 
topcoat application, depainting, chemical milling maskant application, 
and the handling and storage of waste. The proposed rule would apply to 
all organic HAP emission points within these operations located within 
aerospace manufacturing or rework facilities that are major sources. In 
addition, the proposed rule would require control of emissions from 
these operations if they are performed in any of the operations for 
which standards are not being proposed. For example, hand-wipe cleaning 
operations are performed at several stages within composite processing 
operations. The hand-wipe cleaning operation, a process covered by the 
proposed standard, would be subject to the standard, regardless of 
where in the facility it occurred.
    Standards are being proposed for inorganic HAP emissions from 
primer application, topcoat application, and depainting operations.
    A discussion of the rationale for including or excluding in this 
proposed rule the basic processes listed in Section V.A. is presented 
below.
1. Operations for Which Standards Are Being Proposed
    a. Organic HAP emissions. As noted above, the EPA is proposing 
organic HAP emission standards for cleaning, primer application, 
topcoat application, depainting, and chemical milling maskant 
application, and the handling and storage of waste. Together, these 
operations are estimated to account for approximately 94 percent of the 
organic HAP emissions from the industry--cleaning, 87.5 percent; 
primers and topcoats, 2.1 percent; depainting, 2.6 percent; and 
chemical milling maskants, 1.5 percent.
    Based on the information obtained from the section 114 
questionnaires and meetings with the industry, there are many readily 
available techniques to achieve substantial emission reductions in each 
of these operations. For example, many chemical milling maskant 
operations were reported as using either solvent-based chemical milling 
maskants with control devices or waterborne chemical milling maskants. 
With regard to cleaning operations, many product reformulations are 
available for hand-wipe cleaning, and there are several equipment and 
work practice standards for spray gun cleaning that reduce organic HAP 
emissions. While methylene chloride chemical stripping is the prevalent 
method for depainting aerospace vehicles, many facilities are using 
non-HAP alternatives. These alternatives are being used by both 
commercial and military facilities to reduce emissions from depainting 
operations. Sufficient data exist for establishing MACT based on non-
HAP alternatives for both commercial and military depainting 
operations. Therefore, these processes are included in the proposed 
rule. Section 114 questionnaire data and the existence of State and 
local regulations identify the use of high transfer efficiency spray 
guns in the aerospace industry. Adequate information exists for 
establishing MACT for the method of application of primers and topcoats 
and for limiting the organic HAP content of the coatings. Based on 
section 114 questionnaire data, nearly all facilities employ 
housekeeping measures to control emissions from waste storage. 
Sufficient data exist, therefore, to establish MACT.
    In summary, based upon their relative contribution to overall 
organic HAP emissions and the use of demonstrated emission control 
technologies and techniques to achieve emission reduction, the EPA 
selected these operations for regulation.
    b. Inorganic HAP emissions. The EPA is proposing inorganic HAP 
emission standards for primer application, topcoat application, and 
depainting operations. Based on section 114 questionnaire responses, 
there are readily available techniques that are used extensively in the 
industry to control these emissions. While the inorganic HAP emissions 
do not represent a large percentage of overall emissions from the 
industry, the emissions represent potential threats to health because 
of the highly toxic nature of the inorganic HAP (e.g., chromium and 
cadmium). For these reasons, the EPA selected these operations for 
regulation.
2. Excluded Operations
    The EPA is not proposing standards for four non-coating related 
operations--chemical milling, metal finishing, electrodeposition, and 
composite processing--and for four coating-related operations--
adhesives, adhesive bonding primers, sealants, and specialty coatings.
    Organic HAP emissions were reported from all four of the non-
coating related processes. Emissions from these four operations account 
for less than 1 percent of the total organic HAP emissions from 
aerospace facilities. Most of the organic HAP emissions from these 
operations are due to emissions from the use of cleaning solvents, 
which are being proposed for regulation under the proposed rule. The 
EPA has determined that requiring control of the remaining organic HAP 
emissions is not feasible because no demonstrated control measures 
could be identified. Therefore, the EPA is proposing no further control 
for organic HAP emissions from these four operations other than what 
would be achieved by the proposed standards for cleaning solvents.
    The four coating-related operations--adhesives, adhesive bonding 
primers, sealants, and specialty coatings--are similar in many ways to 
primers and topcoats, for which organic HAP emission standards are 
being proposed. These four coating-related operations account for 
relatively small amounts of organic HAP emissions, and the coatings 
tend to be very specialized. Subcategorization can be significant, 
especially for specialty coatings, resulting in lower potential 
emission reductions. Many of the coatings in these four operations 
(e.g., sealants and adhesives) are already being applied using high 
transfer techniques, including hand application. This results in little 
opportunity for emission reduction through improved transfer 
efficiency. For spray applied sealants, there is also little 
opportunity to use higher transfer efficiency equipment because the 
viscosity of these sealants requires the use of high pressure, 
conventional spray guns. In terms of potential emission reduction from 
lower organic HAP content coatings, virtually no organic HAP content 
data were available to categorize these coatings. The time necessary to 
gather the data would have significantly delayed this proposed rule. 
For all of these reasons, standards are not being proposed for these 
operations.
    Wastewater and storage tanks emit relatively small amounts of HAP 
and, according to the section 114 questionnaire responses, no aerospace 
facilities used any means to control these emissions. The EPA then 
considered the option of requiring applicable controls used in other 
industries on these types of sources. These control measures were 
evaluated and found to be too costly when compared to the emission 
reductions that would be achieved (approximately $126,000 per ton of 
HAP emissions reduction for storage tanks).
    Other requirements in the standards may result in a direct 
reduction of emissions from wastewater and storage tanks. For example, 
the depainting standards may eliminate the majority of the estimated 
152 million gallons of HAP-containing chemical stripper usage if the 
majority of sources use media blasting methods. This stripper is 
typically treated in wastewater treatment systems after use. Also, the 
hand-wipe cleaning standards will virtually eliminate the storage tanks 
for organic HAP-containing solvents since the use of these solvents 
will be significantly reduced. For these reasons, the EPA is not 
proposing to regulate HAP emissions from wastewater and storage tanks 
in the proposed rule.

E. Selection of the Basis for the Proposed Rule

    Section 112 of the Act defines a major source as any stationary 
source that emits 9.1 Mg/yr (10 tpy) or more of any one HAP or 22.7 Mg/
yr (25 tpy) or more of total HAP. The Act states that new major sources 
must achieve the maximum achievable control technology (MACT), which is 
the level of emission control already achieved in practice by the best 
controlled similar source. The Act further states that emission 
standards promulgated for existing sources may be less stringent than 
standards for new sources; however, standards for existing sources must 
not be less stringent than the average emission limitation achieved by 
the best performing 12 percent of the existing sources.
    For all operations being covered by the proposed rule, the EPA has 
determined that, taking into account cost, nonair quality health and 
environmental impacts, and energy impacts, MACT is equal to the MACT 
floors for both existing and new sources. In addition, MACT for new 
sources was found to be equal to MACT for existing sources. The EPA has 
determined that no further emission reductions can be achieved for new 
sources through the use of demonstrated technology than the level of 
reduction represented by MACT for existing sources.
    To evaluate the regulatory alternatives, model plants were 
developed based on market segment (commercial or military), work type 
(OEM or rework), and size (small, medium, or large). These 
characteristics were examined to determine whether any technological 
justification existed to differentiate the proposed standards by market 
segment, work type, or size. Based on this examination, the EPA has 
determined that, other than one exception under the depainting 
standards, there is no justification for differentiating between these 
characteristics. For example, rework facilities are required to conform 
to OEM specifications, which dictate the processes and coatings that 
can be used. Consequently, rework facilities do not typically 
incorporate technology that is not used by the OEM's. Also, no 
compelling reasons were identified as to why a facility of one size 
could not incorporate the technology used by a facility of another 
size.
1. Cleaning Operation
    According to data obtained from the Bureau of the Census, 
approximately 25 percent of facilities with aerospace manufacturing SIC 
codes are located in California. Based on information provided by four 
California districts--SCAQMD, Imperial County Air Pollution Control 
District (APCD), Ventura County APCD, and San Diego APCD--virtually all 
of the California facilities are located in these districts, and more 
than half are located in the SCAQMD alone. Based on this information, 
more than 12 percent of the total number of sources are, then, subject 
to the rules in these four districts.
    Consequently, the regulations in these four districts (i.e., SCAQMD 
Rule 1124, Imperial County APCD Rule 425, Ventura County APCD Rule 
74.13, and San Diego APCD Rule 67.9) were examined to determine the 
emission limitations in these districts. These regulations specify 
vapor pressure limits and housekeeping measures for hand-wipe cleaning 
solvents. The EPA then investigated to determine if the regulations 
resulted in California facilities emitting less HAP from this process 
than facilities outside of California. Based on the section 114 
questionnaire responses, California facilities emitted approximately 48 
percent less HAP than non-California facilities in ozone nonattainment 
areas for hand-wipe cleaning operations. These emissions were 
calculated on a pounds of HAP emitted per employee basis, using the 
total number of employees at the facilities (the number of employees 
for hand-wipe cleaning only was not available). The conclusion made 
from these data was that the California regulations are an effective 
means of producing permanent and quantifiable emission reductions, and 
that the sources subject to these regulations are the best-performing 
sources in this source category. Since these sources also comprise more 
than 12 percent of the sources in the category, the MACT floor was 
based on their control levels.
    It was impossible to distinguish the separate effects of 
housekeeping and vapor pressure limits on the emission rates from hand-
wipe cleaning operations. Consequently, both were assumed to be 
necessary to achieve the calculated emission reductions. While one 
cannot ``average'' housekeeping measures, based on common aspects among 
the four rules, housekeeping measures of maintaining closed containers 
for the storage of fresh solvent, spent solvent, and solvent-soaked 
cloth and paper were established as one part of the MACT floor.
    The second part of the MACT floor for hand-wipe cleaning is a vapor 
pressure limitation on the solvents being used. The SCAQMD, the San 
Diego AQMD, and the Imperial County APCD specify a maximum vapor 
pressure of 45 mm Hg at 20  deg.C. Ventura County APCD specifies 25 mm 
Hg at 20  deg.C. However, the EPA believes that it is inappropriate to 
give equal weight to the Ventura rule in determining the MACT floor 
because this district contains only three aerospace facilities compared 
to the hundreds located in the South Coast and San Diego districts. 
Furthermore, industry comments suggested that these three facilities 
are not representative of the industry and do not constitute a similar 
source as required by the Act. The EPA did, however, consider a 
weighted average vapor pressure limitation, but the vapor pressure 
value obtained did not correspond to any demonstrated technology. Since 
more than half, and possibly as much as 90 percent, of the aerospace 
facilities in California are located in the South Coast district, the 
EPA has determined that the 45 mm Hg vapor pressure is more 
representative of the ``average'' limitation on cleaning solvents among 
the best performing facilities and represents the MACT floor for both 
new and existing sources. More stringent levels (e.g., a weighted 
average vapor pressure value) were not considered to be achievable by 
all sources. Therefore, the EPA has selected the 45 mm Hg at 20  deg.C 
(24.1 in. H2O at 68  deg.F) as the basis for the standards for 
hand-wipe cleaning solvents.
    Information collected on cleaning solvents also showed that some 
hand-wipe cleaning solvents have both a very low vapor pressure and a 
very low evaporation rate. Available data indicate that low evaporation 
rates also contribute to minimizing emissions. These cleaning solvents 
are demonstrated technology for limited applications and their use 
would reduce organic HAP emissions as much as or more than the proposed 
vapor pressure limit. Therefore, the EPA is proposing to encourage 
their use by including an approved composition list for cleaning 
solvents in the proposed rule. The EPA welcomes comments on this list 
and proposals for adding to the list before final promulgation of the 
rule.
    Based on data provided by aerospace facilities in response to the 
section 114 questionnaires, spray guns used to apply coatings are 
cleaned either manually or in enclosed gun cleaners. Based on 
information obtained during plant visits, enclosed gun cleaners are 
demonstrated to reduce emissions.
    Each of the 61 facilities that reported a spray gun cleaning method 
was classified as to whether the spray guns were cleaned manually or 
with an enclosed cleaner. Eighteen of the 61 facilities (29 percent) 
reported using enclosed gun cleaners; therefore, enclosed gun cleaners 
were considered to represent the MACT floor level of control. The EPA 
also received information from the industry on the use of cleaning 
methods other than enclosed gun cleaners. After review of this 
information, the EPA determined that adequate technical justification 
was presented to show that the alternate cleaning methods were as 
effective as enclosed spray gun cleaners in controlling organic HAP 
emissions. Consequently, in addition to enclosed spray gun cleaners, 
the EPA is proposing to allow the use of: (1) Unatomized discharge of 
solvent into a waste container that is kept closed when not in use, (2) 
hand cleaning in a vat that is kept closed when not in use, and (3) the 
use of atomized spray into a waste container fitted with a device 
designed to capture atomized solvent emissions.
    Based on information received from the responses to the section 114 
questionnaires, plant visits, and industry meetings, the EPA learned 
that there are certain cleaning operations for which low VOC, low HAP, 
or low vapor pressure cleaning solvents do not have widespread use that 
would constitute a demonstrated technology. The EPA, therefore, is 
proposing to exempt these cleaning operations from the requirements to 
use cleaning solvents that conform to the approved composition list and 
the proposed vapor pressure limit of 45 mm Hg at 20  deg.C (24.1 in. 
H2O at 68  deg.F). These operations are listed in Sec. 63.744(e) 
of the proposed rule.
    The use of cleaning solvents that conform to the approved 
composition list is not yet demonstrated for the proposed exempt 
cleaning operations. However, there are many new cleaning solvents 
being developed, some of which are very close to being used within the 
industry for some of these proposed exempt cleaning operations. To 
encourage the use of available compliant cleaning solvents and the ones 
being developed, the EPA considered imposing a limit on the annual 
usage of non-compliant cleaning solvents for exempt operations. 
However, no data were available for use in establishing this limit.
2. Primer and Topcoat Application Operations
    As noted above, over 12 percent of the aerospace industry is 
located in four districts in California. The SCAQMD, Ventura County 
APCD, Imperial County APCD, and Sacramento Metropolitan AQMD rules all 
require high transfer efficiency coating application methods. The 
application methods specified in these rules were adopted as the MACT 
floor. The specified methods are electrostatic application, flow coat 
application, dip coat application, roll coating, brush coating, and 
HVLP spraying.
    The EPA recognizes that there may be other application methods that 
achieve a level of emissions equivalent to the application methods 
allowed in the proposed rule. Therefore, the EPA is requesting comments 
identifying these other application methods. These comments should 
include test data demonstrating that, in actual production conditions, 
the application method achieves a level of emissions at least 
equivalent to the level of emissions achieved by HVLP or electrostatic 
spray application methods. The EPA will review these comments and, 
where adequate technical justification exists, amend the list of 
approved application methods.
    The EPA also examined whether or not there are demonstrated low 
organic HAP content primers or topcoats that could be used in 
conjunction with high transfer application methods to establish the 
MACT floor to reduce emissions. To this end, the EPA examined State and 
local regulations and the data obtained through the section 114 
responses.
    State and local regulations for aerospace coatings use VOC content 
as the means of regulating coating emissions. Consequently, no directed 
effort has been made to control the organic HAP content of these 
coatings. Data on coating VOC content are readily available from both 
the coating manufacturers and the coating users, but no comprehensive 
data exist for coating organic HAP content.
    The data obtained from the section 114 responses showed that the 
organic HAP content varies widely and randomly with the VOC content. 
This is not surprising since, as noted above, there have been efforts 
to limit only the VOC content in the coatings and not the organic HAP 
content. However, the data show that the organic HAP content is 
typically 50 percent less than the VOC content. Where the organic HAP 
content was higher than the VOC content, the EPA found that this was 
the result of the use of exempt solvents (those solvents determined by 
the EPA to have negligible photochemical reactivity) that are also 
organic HAP.
    There are a number of chemicals commonly found in coatings that are 
not on the list of 189 HAP (section 112(b) of the Act) including methyl 
amylketone (2-heptanone), cyclohexanone, and isopropyl alcohol. 
Currently, the EPA does not have adequate health data to determine the 
relative toxicity of these organic HAP substitutes and, therefore, does 
not want to establish a requirement that would encourage their use as 
substitutes in coatings. Since these potential substitutes are also 
VOC, the proposed standards would limit both organic HAP and VOC 
content, rather than organic HAP only. The effect of this dual limit 
will be to reduce the total amount of organic emissions from coating 
operations, eliminate the use of the few very high organic HAP content 
primers and topcoats, and establish a cap on the organic HAP content of 
primers and topcoats that will be developed in the future.
    The organic HAP and VOC limits were determined by ranking the 
facilities that reported usage of primers or topcoats from the lowest 
to the highest weighted average VOC content of all primers or topcoats 
used at the facility. The weighted average VOC content that represented 
the average of the best 12 percent was selected as the VOC limit. This 
value was 350 g/l (2.9 lb/gal) for primers and 420 g/l (3.5 lb/gal) for 
topcoats. As discussed earlier, the limited data available to the EPA 
indicate that organic HAP content is typically lower than VOC content. 
However, no reasonable limit could be identified. Therefore, the EPA is 
proposing an organic HAP content limit at the same level as for VOC. 
The proposed limits for organic HAP are, therefore, 350 g/l (2.9 lb/
gal) for primers and 420 g/l (3.5 lb/gal) for topcoats.
    The section 114 questionnaire responses showed that the inorganic 
HAP emissions from nearly all primer and topcoat application operations 
were controlled by dry particulate filters or waterwash spray booths. 
Since no other technology was identified that can be used to control 
inorganic HAP emissions, the use of filters and waterwash was adopted 
as the MACT floor.
3. Depainting Operation
    The information obtained on depainting operations showed the 
pervasive use of organic HAP-containing chemical strippers to remove 
paint. However, information was also obtained showing that many 
aerospace depainting operations are using alternative methods that do 
not utilize organic HAP, including organic HAP-free chemical strippers 
and dry media blasting techniques. The information also showed that not 
all commercial aerospace vehicles are fully coated. In these instances, 
the amount of organic HAP emissions from depainting is less than it 
would be if the same vehicle were fully coated.
    The quantity of organic HAP emissions from depainting operations at 
several commercial rework facilities was readily available. However, 
very limited emissions data were obtained through the section 114 
questionnaire responses for military aircraft depainting operations. 
The EPA considered several parameters to establish which facilities 
were the best performing ones. The most simple method would be to 
determine the pounds of organic HAP emissions per aircraft. This would 
not, however, take into account the difference in outer surface area 
from one model of aircraft to another and, hence, the difference in 
stripper volume required for each aircraft. Another basis would be to 
determine the organic HAP emissions per square foot of outer surface 
area actually painted. This method would not distinguish between the 
total emissions for stripping an aircraft that has only a portion of 
the outer surface area painted, and the total emissions for stripping 
the same aircraft with the entire outer surface area painted. 
Therefore, both methods were rejected.
    Another basis for determining the best performing operations 
relates the pounds of organic HAP emissions to the total outer surface 
area of the aircraft. This effectively takes into account the 
effectiveness of all methods used to depaint aerospace vehicles and 
distinguishes the lower emissions achieved when only a portion of the 
outer surface area is painted from the emissions when a larger portion 
is painted. However, insufficient data were obtained through the 
section 114 questionnaire responses to develop an emission rate for 
military aircraft depainting operations.
    A fourth consideration was to identify the basic techniques being 
used and rank them according to their relative effectiveness in 
reducing organic HAP emissions. The EPA elected to use this as the 
measure for identifying the best performing facilities. The different 
depainting techniques were also evaluated as to their applicability 
throughout the industry.
    Three basic depainting techniques are used by the facilities for 
which the EPA has information: Methylene chloride based chemical 
strippers, chemical strippers that contain no organic HAP, and blasting 
methods. (Although blasting methods are very effective in reducing and 
essentially eliminating organic HAP emissions from depainting 
operations, they do produce particulate inorganic HAP emissions. 
However, these emissions are typically well-controlled with particulate 
filters, which are almost always integral to the blasting systems. In 
addition, the proposed standards would require such control on 
inorganic HAP emissions, as discussed in section II.B. of this 
preamble.)
    Based on section 114 questionnaires, site visits, and information 
provided by the industry, the EPA has information on depainting methods 
at 20 facilities. Of these facilities, 14 were identified as using 
either a blasting method (i.e., wheat starch or plastic media) or 
chemical strippers that contain no organic HAP.
    The EPA then determined the aircraft models being stripped at each 
of these 14 facilities. This analysis showed that military fighters and 
transports, military and commercial helicopters, civil aircraft, and 
nearly all models of commercial airliners are currently being stripped 
with one or more of these non-HAP methods. Given the wide applicability 
of these processes throughout the industry, the EPA determined the MACT 
floor to be equivalent to the use of either media blasting or chemical 
strippers that do not contain organic HAP.
    This analysis also showed, however, that some organic HAP emissions 
from depainting still occurred at facilities using blast methods or 
chemical strippers that contain no organic HAP. This is due to the fact 
that certain parts (e.g., wing flaps, engine nacelles, and radomes) are 
removed from the aircraft and depainted separately. This is primarily 
due to the fragile nature or specific depainting needs of these parts. 
Due to the wide range of parts removed and the inconsistency in the 
type of parts removed from one model of aircraft to another, the 
applicability of using blast techniques or chemical strippers that 
contain no organic HAP on these parts could not be determined. 
Consequently, these parts are exempted from the proposed standards.
    In addition, the EPA determined that a small portion of the 
aircraft cannot be stripped with blasting methods. For example, some 
areas of the aircraft are masked to prevent intrusion of the blast 
media. The edge of the masking will often cover coated areas and, thus, 
prevent the blasting media from removing the coating from these areas. 
This coating must then be removed (referred to as spot stripping), 
usually with an organic HAP-containing chemical stripper. Another 
example of spot stripping is the removal of coatings from a small area 
of the outer surface of the aircraft in order to perform testing and 
inspection of the bare metal. Also, blasting methods may have 
difficulty removing some decals. Consequently, organic HAP solvents may 
be used to soften or remove these decals. For these reasons, exemptions 
for spot stripping and decal removal are necessary in order to allow 
the use of blast depainting methods to meet the proposed standards.
    The EPA did, however, seek to limit the amount of organic HAP-
containing chemical strippers used for radome, parts and spot stripping 
and decal removal. Data provided in the section 114 questionnaire 
responses were used to establish the amount of stripper used for these 
operations. Data were not available for radome and parts depainting; 
however, usage of chemical strippers for spot stripping and decal 
removal was available from commercial airlines for a limited number of 
aircraft types. Since information was not available for all aircraft 
types, the stripper usage for the largest commercial aircraft was used 
as the basis for the usage exemption.
    The usage information was, however, limited to commercial aircraft. 
Military sources within the aerospace industry provided additional data 
to the EPA that established a technical justification for a higher 
usage limitation for military aircraft. This information was used as 
the basis for the usage limitation for spot stripping and decal removal 
for military aircraft.
    The section 114 questionnaire responses showed that all facilities 
(7 respondents) that use media blasting to depaint use either dry 
particulate filters or baghouses to control particulate emissions from 
blast depainting methods. While electrostatic precipitators were 
identified as a possible control technology, the cost of the 
precipitators was believed to be considerably higher than the 
filtration methods already in use. Therefore, particulate filters and 
baghouses were used as the basis for developing the MACT floor for 
operations that use media blasting.
4. Chemical Milling Maskant Application Operation
    Not all aerospace facilities perform chemical milling maskant 
operations. Of those responding to the section 114 request, twelve 
reported chemical milling operations. To identify the best performing 
twelve percent of the sources, the emission rate for each source was 
calculated by dividing the organic HAP emissions by the total usage of 
chemical milling maskants to obtain pounds of organic HAP emitted per 
gallon of chemical milling maskant (less water) as applied. The 
emissions value took into account control measures such as carbon 
adsorbers or waterborne chemical milling maskants. The sources were 
then ranked from the lowest emission rate to the highest.
    For this operation, the best performing 12 percent of the sources 
is represented by the two sources with the lowest emission rates. One 
of these sources utilized a carbon adsorber to abate the emissions from 
a solvent-based chemical milling maskant. The other source utilized a 
waterborne chemical milling maskant with no abatement. Each of these 
two facilities had the same organic HAP emission rate of 1.3 lb/gal. 
Therefore, this was selected to represent the MACT floor.
5. Handling and Storage of Waste
    Based on the section 114 questionnaire responses, 181 non-
wastewater waste streams were reported. Every stream was controlled by 
housekeeping measures such as keeping the waste material in closed 
drums. Thus, housekeeping measures were established as the MACT floor 
for handling and storage of waste.
    While no data were available for the effect on emissions from the 
housekeeping measures, it is expected that emissions will be reduced 
based on the data from California facilities for keeping cleaning 
solvents in closed containers. Consequently, housekeeping measures were 
used as the basis for the proposed standard.
    In addition, existing RCRA regulations govern handling and storage 
practices for certain types of wastes. Since the EPA did not want to 
create a situation where possible conflicts with the RCRA regulations 
could arise, the proposed rule exempts wastes covered under the RCRA 
regulations.

F. Selection of the Format of the Proposed Rule

    Several formats could be used to implement the control techniques 
selected as the basis for the proposed standards. Section 112(d) of the 
Act requires that emission standards for control of HAP be prescribed 
unless, in the judgment of the Administrator, it is not feasible to 
prescribe or enforce emission standards. Section 112(h) of the Act 
defines two conditions under which it is not feasible to prescribe or 
to enforce emission standards. These conditions are: (1) If the HAP 
cannot be emitted through a conveyance device or (2) if the application 
of measurement methodology to a particular class of sources is not 
practicable due to technological or economic limitations. If emission 
standards are not feasible to prescribe or enforce, then the 
Administrator may instead promulgate equipment, work practice, design 
or operational standards, or a combination thereof.
1. Cleaning Operation
    The cleaning operation for which the EPA is proposing standards 
emits a variety of organic HAP. For many of these organic HAP, emission 
measurement methods either do not exist or would be very expensive to 
implement. In addition, the nature of some cleaning operations (e.g., 
hand-wipe cleaning) makes collection through a conveyance device 
difficult if not impossible. Therefore, the EPA determined that 
emission standards are not feasible for these operations.
    The EPA then considered design, equipment, work practice, and 
operational standards for these operations. The EPA examined the 
California regulations, which had been determined to represent the 
floor level of control, to identify the specific types of measures 
adopted for hand-wipe cleaning, flush cleaning, and spray gun cleaning. 
An analysis by the EPA of the aerospace facilities' data showed that 
facilities subject to the California requirements emitted approximately 
48 percent less organic HAP from their operations than non-California 
operations in ozone nonattainment areas. The EPA concluded that the 
formats of the California regulations are effective in providing 
quantifiable and achievable emission reductions. Therefore, the same 
formats are being proposed for the NESHAP as follows: (1) For hand-wipe 
cleaning operations, use of solvents that conform to the approved 
composition list or vapor pressure limits, and housekeeping measures, 
(2) for spray gun cleaning, an equipment standard and housekeeping 
measures, and (3) for flush cleaning, housekeeping measures.
    The EPA is also proposing standards to limit the organic HAP 
emissions that may occur from leaks from enclosed spray gun cleaners. A 
format based on emission limits was not possible, since there were no 
data to determine the emissions from leaks. Also, no design, equipment, 
or work practice standards were identified that would prevent leaks 
from occurring. Consequently, the EPA determined that the only format 
that would ensure a minimum of organic HAP emissions from leaks was an 
operational standard that required leaks to be repaired within a 
certain amount of time.
2. Primer and Topcoat Application Operations
    The formats selected by the EPA for the proposed organic HAP 
emission limits for primer and topcoat application operations are: (1) 
A limitation on both the VOC and organic HAP content, (2) a percent 
reduction and performance standard for control devices, and (3) an 
equipment standard for the application of primers and topcoats.
    The EPA considered a format based on actual emissions from the 
primer and topcoat application operations. However, the EPA has 
information that many larger facilities have several hundred spray 
booths in which primer or topcoat application operations could take 
place. Monitoring of that many individual emission sources would not be 
feasible for either the facility or for enforcement of the standards by 
the EPA or state agencies. In addition, actual emissions would have to 
be linked to the production rate and the product produced at the 
facility. The EPA does not have adequate data to quantify emissions 
based on production or the product produced. Therefore, the EPA 
rejected this format.
    The EPA then considered a limitation on the organic HAP and VOC 
content (mass of organic HAP and VOC per unit volume) of coating as 
applied. This format would essentially impose an emission limitation on 
each source, but allow flexibility in the manner of compliance. Each 
source would have the choice of using compliant coatings and averaging 
between compliant and non-compliant coatings. This format will reduce 
the amount of total organics, is easily enforced with Method 24 for VOC 
content and manufacturer's data for organic HAP content, and will cap 
the total amount of organic HAP that a primer or topcoat can contain.
    The EPA is also allowing the use of control devices to reduce 
organic HAP and VOC emissions from primer and topcoat application 
operations. The format of the standards must ensure that as much of the 
emissions as practicable are being controlled. The EPA chose a format 
that specifies the overall control efficiency (capture efficiency 
multiplied by the removal efficiency) because overall control 
efficiency is the best representation of the control effectiveness of 
control devices. It is also easily enforceable since the EPA has 
published test methods for both capture and removal efficiency.
    The EPA is proposing to set an equipment standard to reduce HAP 
emissions from the application of primers and topcoats. This format 
requires the use of certain specified coating application equipment or 
coating methods that result in higher transfer efficiencies than 
conventional spray equipment, thus reducing emissions. This format 
allows facilities the flexibility to choose the method of application 
most appropriate to the coating and substrate being coated.
    The EPA first considered the data presented in the section 114 
questionnaire responses to determine the format of the standards for 
inorganic HAP emissions from primers and topcoats. The level of control 
(expressed as a percentage) of dry particulate filters and waterwash 
spray booths was reported in the section 114 questionnaire responses. 
However, the basis for the reported control efficiency was primarily 
engineering judgement and manufacturer's data, which could not be 
verified through standardized testing. While the Act specifies that 
emission standards be developed whenever possible, the EPA determined 
that the available data were not of sufficient quality to develop such 
a standard.
    The EPA then considered an equipment standard that described 
physical characteristics of high efficiency particulate filters and 
waterwash systems. However, due to the number of different filter and 
waterwash systems and variety of designs available, no concise 
description could be developed.
    The EPA then developed a format that specified that all primer and 
topcoat application operations must be conducted in a ventilated booth 
or hangar equipped with filters or waterwash systems. The selection of 
the actual filters and waterwash systems would be left to the 
individual facilities.
3. Depainting Operation
    The demonstrated technologies for depainting that represent the 
best performing 12 percent of sources are blast methods (e.g., plastic 
media and wheat starch blasting) and chemical strippers that contain no 
organic HAP. The EPA considered an operational format for the proposed 
standards that would require one of these methods to be used. However, 
many other alternative depainting methods are under development that 
have the potential to reduce organic HAP emissions as effectively as 
blasting or chemical strippers that contain no organic HAP. The EPA did 
not want to limit the development of these alternative depainting 
methods, so the operational format was rejected.
    The EPA then considered the level of organic HAP emissions from 
blasting, chemical strippers that contain no organic HAP, and other 
alternative depainting methods. With the exception of spot, decal, 
radome, and parts depainting, all of these methods have the potential 
to emit no organic HAP. The EPA, therefore, chose an emission standard 
format that specifies no organic HAP emissions from depainting, with 
exemptions for spot, decal, radome, and parts depainting. This format 
would allow the currently demonstrated depainting methods, as well as 
alternative methods that may be developed in the future.
    While spot stripping and decal removal have been exempted from the 
proposed standards, the EPA, in selecting the format of the exemption, 
intends to limit the use of organic HAP-containing stripper to the 
lowest amount necessary. The EPA selected a limitation on the annual 
average amount (in gallons) of organic HAP-containing stripper used per 
aircraft.
    The format for the proposed standards for inorganic HAP emissions 
from depainting operations was developed from the section 114 
questionnaire responses. The seven facilities that reported blast 
depainting operations were ranked according to control efficiency of 
the filtration methods (particulate filters or baghouses) used to 
control particulate emissions. The best performing 12 percent of these 
sources are represented by the one facility with the highest control 
efficiency. This facility achieved a reported control efficiency of 99 
percent and was chosen to represent the MACT floor.
    The control efficiency data reported in the section 114 
questionnaire responses consisted of engineering judgement estimates 
and information obtained from the filter manufacturers. No test data 
were reported. Due to this lack of quantifiable test data, the EPA is 
requesting comments on whether the 99 percent level of control 
represents the demonstrated level of technology for the control of 
particulate emissions from blast depainting. These comments should 
contain a technical justification, including test data where possible, 
for any recommended level of control.
4. Chemical Milling Maskant Application Operation
    An emission limitation based on the mass of organic HAP and VOC per 
unit volume applied was selected for chemical milling maskants. There 
are essentially two means of complying with the proposed standards: (1) 
Solvent-based chemical milling maskant with a carbon adsorber to reduce 
emissions or (2) a waterborne chemical milling maskant with an organic 
HAP content equal to or less than the proposed standard. This format 
allows facilities to choose either method (or develop an equivalent 
method) without giving preference to either solvent-based or waterborne 
chemical milling maskants.
5. Handling and Storage of Waste
    The rationale for the format of the proposed standards for handling 
and storage of waste is essentially the same as that for housekeeping 
measures for cleaning solvents. Since no data were available to 
establish an emission limitation and control equipment was not 
technically feasible, a work practice format requiring housekeeping 
measures was selected as the most appropriate means of reducing 
emissions.

G. Selection of Emission Test Methods and Monitoring Requirements

1. Emission Test Methods
    In addition to the specific test methods described below for each 
affected source, the proposed rule adopts the provisions specified in 
Sec. 63.7 of the General Provisions, 40 CFR part 63, subpart A.\9\
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    \9\Ibid.
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    a. Cleaning operation. For hand-wipe cleaning, the proposed 
standards would allow owners or operators to use either a cleaning 
solvent that conforms to an approved composition list or a cleaning 
solvent with a vapor pressure less than or equal to 45 mm Hg. 
Procedures are, therefore, necessary for determining whether a cleaning 
solvent conforms to the approved composition list or meets the vapor 
pressure limitation.
    The other portion of the proposed standards for cleaning operations 
(including spray gun cleaning) includes housekeeping measures, 
equipment standards, or work practice standards, for which no test 
methods or procedures are required to demonstrate compliance.
    Those facilities that use cleaning solvents that conform to the 
approved composition list would have to demonstrate how the solvents 
comply. The EPA is proposing that data supplied by the manufacturer of 
the cleaning solvent be used to show compliance. The data must show all 
components of the cleaning solvent and demonstrate that one of the 
approved composition definitions is met.
    To determine the composite vapor pressure of a cleaning solvent, 
the EPA is proposing that for single-component cleaning solvents data 
supplied by the manufacturer or from standard engineering reference 
texts be used. This information is readily available and, for single 
component cleaning solvents, should be readily acceptable.
    For multi-component cleaning solvents, it is necessary to determine 
the composite vapor pressure of the cleaning solvent. This requires 
determining the amount of each organic compound in the cleaning solvent 
and each one's vapor pressure. Once these are known, then a procedure 
to combine the information must be followed to calculate the composite 
vapor pressure.
    The EPA is proposing that gas chromatographic analysis, following 
the procedures outlined in E 260-85, be used to quantify the amount of 
each organic compound. The vapor pressure of each organic compound 
would then be determined, again, either by the manufacturer's data or 
from standard engineering reference texts, as discussed above. For 
combining these data to calculate the composite vapor pressure, the EPA 
is proposing that the blend be assumed to be an ideal solution where 
Raoult's law applies. While more accurate methods are available, the 
cost and time to conduct those methods and the small gain in accuracy 
are not justifiable when compared to the ease of calculating composite 
vapor pressure assuming an ideal solution where Raoult's law applies. 
Further, the composite vapor pressure of any blend changes with the 
conditions under which it is applied. This normal variability would 
cause some cleaning solvents to meet the composite vapor limit under 
certain conditions, but not others, if the vapor pressure test methods 
were used instead of the calculation.
    b. Primer and topcoat application operations. One part of the 
proposed standards for primer and topcoat application operations 
requires the use of specified high transfer efficiency application 
equipment, or equivalent.
    As long as this equipment is installed, operated, and maintained 
according to manufacturer's specifications, it should perform with high 
transfer efficiency. Therefore, the EPA is not proposing any test 
methods or procedures for this part of the primer and topcoat 
standards.
    Owners or operators who want to use application equipment other 
than that specified in the proposed rule must demonstrate that it is 
equivalent in reducing organic HAP and VOC emissions. To make an 
equivalency determination, the owner or operator must demonstrate that 
the organic HAP and VOC emissions generated by the alternative method 
are equal to or less than the emissions generated by HVLP or 
electrostatic spray guns under the actual production conditions in 
which the alternative method is intended to be used. This level of 
emissions is equivalent to the emissions demonstrated by California 
facilities that are subject to similar rules.
    Before implementing the alternative application method, the 
facility must determine the organic HAP and VOC emissions that were 
generated by the process over the 90-day period immediately preceding 
the implementation of the alternative application method. During this 
initial 90-day period, only HVLP or electrostatic spray guns could be 
used. These emissions would be compared to the organic HAP and VOC 
emissions generated by the same process using the alternative 
application method to coat an equivalent amount of parts and assemblies 
as coated during the initial 90-day period using identical coatings. 
The organic HAP and VOC emissions generated during the use of the 
alternative application method must be equal to or less than the 
emissions generated during the initial 90-day period.
    In determining compliance with the organic HAP and VOC content 
levels, an owner or operator would have the flexibility to use 
compliant coatings or to average uncontrolled compliant and non-
compliant coatings. (Averaging between primers and topcoats would not 
be allowed, nor would averaging between controlled and uncontrolled 
coatings.) Test methods and procedures are, therefore, necessary to 
determine the organic HAP and VOC content of each primer and topcoat as 
applied.
    The EPA is proposing that Method 24 be used for determining the VOC 
content. This is a long-standing method for such determinations. 
Sources may, at their discretion, use manufacturer's data for 
determining the VOC content rather than Method 24. However, if there is 
found to be a difference in the VOC content as determined from the 
manufacturer's data and that determined using Method 24, then the value 
obtained using Method 24 will always take precedence in compliance 
determinations. Since there are no generally available methods for 
testing organic HAP content, the EPA is proposing that the organic HAP 
content level be determined by each facility based on the formulation 
of each coating. The formulation data would be supplied to the facility 
by the coating manufacturer. This would reduce the burden to the 
industry and promote consistent identification of the total organic HAP 
content among all users. Several coating manufacturers have indicated 
to the EPA that they are willing to supply such information.
    As noted above, the proposed standards would require the organic 
HAP contents to be determined on a ``less water as applied'' basis and 
VOC contents on a ``less water and exempt solvents as applied'' basis. 
Thus, unless the coating is applied as received, procedures must be 
adopted to change ``as received'' organic HAP and VOC content levels to 
``as applied'' levels. This could be accomplished by analyzing a sample 
of the coating as applied using Method 24 or through a calculation. The 
calculations to do this are well known and established (see A Guideline 
for Surface Coating Calculations, EPA-340/1-86-016, July 1986) and, 
thus, the EPA did not consider it necessary to include the basic 
calculation formulas in the proposed rule. A determination of what is 
added to the coating before it is applied must be made so that the ``as 
applied'' levels can be calculated. The EPA is proposing that each 
owner or operator make such determinations on the basis of records kept 
at the facility. These are records that will be required by the 
proposed rule and will be readily available to the owner or operator 
for making the necessary calculations. The pertinent information (i.e., 
density, organic HAP content, and VOC content) of the additives would 
be based on manufacturer supplied information. If that information is 
not available, then the owner or operator would be required to develop 
a procedure for determining the missing information for approval by the 
Administrator.
    Since the proposed standards for organic HAP and VOC content levels 
would allow each owner or operator to average organic HAP or VOC 
content levels across uncontrolled primers and across uncontrolled 
topcoats, the procedures provide the necessary formulas to calculate 
the volume-weighted average organic HAP or VOC across all primers or 
topcoats. For compliant coatings, the EPA is proposing less complicated 
procedures for demonstrating compliance. This is appropriate because 
each coating by itself as applied meets the organic HAP (or VOC) 
content level, and daily calculations of the volume-weighted average 
HAP and VOC content as applied are not necessary. The proposed rule 
does, however, require monthly determination of usage and HAP and VOC 
content as applied.
    If control devices (e.g., incinerators, carbon adsorbers) are used, 
the proposed standards require them to achieve an overall control 
efficiency of at least 81 percent. For control devices other than 
carbon adsorbers, it is necessary, therefore, to identify the capture 
efficiency of the capture system, the destruction efficiency of the 
control device, and, where feasible, operational parameters that would 
be monitored to ensure continuous compliance. The proposed standards 
also include provisions for determining the capture and removal 
efficiencies. The test methods and procedures being proposed for 
determining the capture and removal efficiencies are those that are 
typical for control devices.
    The EPA is proposing that capture efficiency be determined by one 
of two methods depending on whether the capture system is totally 
enclosed or not. A total enclosure would be verified according to the 
provisions specified in Sec. 52.741, appendix B, Procedure T of 40 CFR 
part 52 (and, thus would have a capture efficiency of 100 percent). The 
capture efficiency of all other systems would be determined according 
to the procedures specified in Sec. 52.741(a)(4)(iii) of 40 CFR part 
52.
    The EPA is proposing that the removal efficiency of a control 
device be determined based on three runs, each run lasting one hour. 
For control of organic compounds, Method 1 or 1A of 40 CFR part 60, 
appendix A, as appropriate, would be used for selection of the sampling 
sites, and the gas volumetric flow rate would be determined using 
Methods 2, 2A, 2C, or 2D of 40 CFR part 60, appendix A, as appropriate. 
Method 18 of 40 CFR part 60, appendix A, would then be used to measure 
either TOC minus methane and ethane or total organic HAP. 
Alternatively, any other test method or data that has been validated 
according to the applicable procedures in Method 301 of 40 CFR part 63, 
appendix A, may be used.
    Where a carbon adsorber is used, the EPA is proposing to use a mass 
balance procedure for determining the overall control efficiency. The 
proposed rule contains procedures as specified in 40 CFR 60.433 for 
using a mass balance approach that would calculate the amount of 
organic HAP and VOC applied and the amount recovered. This information 
would then be used to calculate the overall control efficiency of the 
carbon adsorber.
    In addition, Method 309 is being proposed for determining the 
number of consecutive 24-hour periods in the rolling material balance 
period for carbon adsorbers.
    Each owner or operator using a control device would be required to 
conduct an initial performance test. For control devices other than 
carbon adsorbers, this test would consist of 3 one-hour runs. For 
carbon adsorbers, the test would span the number of days specified for 
the rolling material balance period as calculated by proposed Method 
309. In addition, it is necessary to establish, during the initial 
performance test, operating parameters that would be continuously 
monitored in order to show continuous compliance. For incinerators 
other than catalytic incinerators, the operating parameter would be the 
firebox temperature. For catalytic incinerators, the operating 
parameters would be the temperature of the gas stream immediately 
before and after the catalyst bed. No operating parameters are required 
to be monitored on carbon adsorbers since the material balance 
calculations provide a continuous check of proper operation.
    c. Depainting operation. The proposed standards for the depainting 
of aerospace vehicles requires, in part, no organic HAP emissions, 
which will be achieved through the use of chemical strippers that do 
not contain any organic HAP or the use of non-chemical depainting 
methods or techniques. Since all of the known non-chemical depainting 
methods/techniques do not contain any organic HAP, the only test method 
or procedures needed are those associated with determining whether a 
chemical stripper contains any organic HAP. For the reasons noted 
earlier under the discussion on test methods for primers and topcoats, 
the EPA is proposing that the organic HAP content be determined based 
on information supplied by the manufacturer of the chemical stripper.
    In order to demonstrate compliance with the organic HAP-containing 
chemical stripper usage limitation for spot stripping and decal 
removal, the source must calculate an average annual usage per 
aircraft. Since there is only one method to calculate this average 
(i.e., dividing the total gallons of organic HAP-containing chemical 
stripper used for spot stripping and decal removal by the number of 
aircraft stripped), the EPA is proposing to use this method to 
determine compliance. The information needed for this calculation would 
be obtained from company records.
    Particulate inorganic HAP emissions are generated by blast 
depainting methods. Therefore, the EPA is proposing that Method 5 of 40 
CFR part 60, appendix A, be used to determine the control efficiency of 
particulate filtration systems used on this process.
    d. Chemical milling maskant application operation. The proposed 
standards for chemical milling maskants limits the organic HAP content 
to the equivalent of 160 grams per liter (1.3 pounds/gallon) less water 
as applied and limits the VOC content to the equivalent of 160 grams 
per liter (1.3 pounds per gallon) less water and exempt solvents as 
applied. In determining compliance with the organic HAP and VOC content 
levels, an owner or operator would have the flexibility to use 
compliant chemical milling maskants or averaging uncontrolled compliant 
and non-compliant maskants. As for primers and topcoats, averaging 
uncontrolled and controlled chemical milling maskants together would be 
prohibited. Test methods and procedures are, therefore, necessary to 
determine the organic HAP and VOC content of each chemical milling 
maskant as applied. If control devices are used, it is also necessary 
to determine the overall control efficiency of the control device. The 
test methods selected and the rationale for the selection are identical 
to those presented above for primers and topcoats.
    e. Handling and Storage of Waste. For those wastes subject to the 
proposed rule, no test methods or procedures are required to 
demonstrate compliance with the proposed housekeeping measures.
2. Monitoring Requirements
    In accordance with paragraph (a)(3) to section 114 of the Act, 
enhanced monitoring of stationary sources is required to determine the 
compliance status of the sources, and whether compliance is continuous 
or intermittent. For affected sources complying with the proposed 
standards through the use of control devices, initial compliance is 
determined through the initial compliance test, and ongoing compliance 
through continuous monitoring. The EPA has proposed the parameters to 
be monitored for certain types of control devices now used in the 
industry. The values of these parameters that correspond to compliance 
with the proposed standards are set by the owner or operator during the 
initial compliance test. If future monitoring indicates that control 
equipment is operating outside of the range of values established 
during the initial performance test, then the owner or operator is out 
of compliance with the proposed standards, except as specified for 
malfunctions in Sec. 63.6(e)(3) of 40 CFR part 63, subpart A.10
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    \1\0Ibid.
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    a. Cleaning operation. For cleaning operations, the only portion of 
the standards for which monitoring requirements are being proposed is 
for enclosed spray gun cleaner systems. These systems are stationary 
sources that have the potential to emit organic HAP from around ill-
fitting or worn seals or from leaking pumps or piping connections. The 
effectiveness of these systems thus depends on their being ``vapor-
tight'' and that there are no leaks from the pumps or piping of these 
systems. Therefore, the EPA is proposing that such systems be visually 
inspected for leaks. Since most of the systems are used to clean paint 
spray guns, leaks would be easily spotted by visual inspection as the 
result of solvent or paint residue escaping around the source of the 
leak. The EPA does not believe that monitoring with leak detection 
equipment would provide a significant increase, if any, in the 
detection of leaks from these systems. Therefore, the EPA is proposing 
to require visual inspection only.
    The EPA then considered how frequently the enclosed cleaners should 
be inspected. The EPA considered daily, weekly, monthly, and yearly 
frequencies. The nature of the systems being inspected is not expected 
to result in sudden failure, but rather failure due to wear and tear. 
Thus, the EPA considered it unnecessary to require daily or even weekly 
inspection. On the other hand, one year was considered too long for a 
leak to go unrepaired. Therefore, the proposed standards would require 
a monthly inspection of the systems. The EPA believes that this is a 
reasonable period between inspections, without overburdening the 
industry and not allowing leaks to go unrepaired for an extended period 
of time.
    Similarly, the proposed work practice and equipment standards 
require that containers used to store solvents and solvent laden cloth 
and paper be closed when not in operation. The EPA could not identify 
any operating parameter that would monitor whether this was being done. 
Nor could the EPA identify a parameter to monitor when atomized 
cleaning is used. The proposed standards require the use of a device 
designed to capture the atomized solvent emissions. No monitoring 
parameters were identified to indicate periods when the device may not 
be functioning or when it may have been removed. Rather, the 
determination would be made during enforcement inspections as to 
whether the proper procedures were being followed.
    b. Primer, topcoat, and chemical milling maskant application 
operations. The proposed monitoring requirements for primer, topcoat, 
and chemical milling maskant application operations concern the 
operation of control devices that may be used in demonstrating 
compliance with the organic HAP content levels. For control devices, 
the parameters to be monitored are those that have been typically used 
in other standards. For example, where catalytic incinerators are used 
to control organic HAP and VOC emissions, the proposed standards 
require that the temperature of the air stream be monitored immediately 
before and after the catalyst bed. The rationale for selecting the 
various control device parameters in this proposed rule is long 
standing, and for more information see the proposal notice for the 
SOCMI reactor processes NSPS (55 FR 26966 through 26969, June 29, 
1990). The EPA is, therefore, simply proposing to adopt the same 
monitoring parameters as have been required for previous standards.
    For inorganic HAP emissions from primers and topcoats, the proposed 
standards would require the use of particulate filters or waterwash 
systems. Two parameters were identified that could be monitored that 
directly relate to the performance of the system--air flow and pressure 
drop. The proposed rule, however, would require monitoring of only the 
pressure drop across the filter or waterwash since the air flow is 
directly related to the pressure drop. Monitoring of both parameters 
was considered to be redundant.
    c. Depainting operation. The nature of the proposed standards for 
depainting operations is such that no meaningful monitoring requirement 
was identified for the proposed organic HAP emission standards. The 
organic HAP content (less water as applied) of the chemical strippers 
used must be calculated or determined. But once identified, there are 
no requirements concerning their application.
    The rationale for the pressure drop monitoring requirements 
proposed for inorganic HAP emissions from depainting operations is 
identical to that for primers and topcoats.
    d. Handling and storage of waste. For those wastes subject to the 
proposed rule, the EPA could not identify any operating parameters that 
would monitor whether housekeeping measures were being performed. 
Therefore, no monitoring requirements are being proposed.

H. Selection of Recordkeeping and Reporting Requirements

1. Recordkeeping
    In addition to the specific recordkeeping requirements described 
below for each affected source, the proposed rule adopts the provisions 
specified in Sec. 63.10 (a), (b), (d), and (f) of the General 
Provisions, 40 CFR part 63, subpart A.11 These were the only 
paragraphs from Sec. 63.10 that were considered to be applicable to the 
proposed rule.
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    \1\1Ibid.
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    a. Cleaning operation. The proposed standards for hand-wipe 
cleaning operations require cleaning solvents to be used that either 
comply with the approved composition list or have a composite vapor 
pressure less than or equal to 45 mm Hg at 20  deg.C (24.1 in. H2O 
at 68  deg.F). In order to determine whether these requirements are 
being complied with, it is necessary to keep data on the cleaning 
solvents being used in these operations. Therefore, the EPA is 
proposing that each owner or operator keep for each cleaning solvent 
used at the facility, a record of the name of the cleaning solvent and 
documentation that shows the organic HAP content and organic HAP 
constituents. In addition, the EPA is proposing the following records 
for specific cleaning operations be kept.
    For each cleaning solvent used in hand-wipe cleaning operations 
that conforms to the approved composition list, the records that would 
be maintained are the name of each cleaning solvent, documentation 
demonstrating compliance to the approved composition list, and annual 
purchasing records showing the annual volume purchased of each. For 
each cleaning solvent used in hand-wipe cleaning operations that does 
not conform to the approved composition list, but does conform to the 
vapor pressure requirement, the information required to be recorded 
would be the name of each cleaning solvent, the monthly usage of the 
cleaning solvent at each operation, the composite vapor pressure, the 
manufacturer's data sheets or other documentation of the vapor 
pressure, and any test reports and calculations performed to determine 
the composite vapor pressure (in order to assess compliance with the 
vapor pressure limit).
    The proposed standards would allow certain hand-wipe cleaning 
operations to be exempt; that is, cleaning solvents that do not comply 
with the approved composition requirements or with vapor pressure 
greater than 45 mm Hg at 20  deg.C (24.1 in. H2O at 68  deg.F) can 
be used for these exempt cleaning operations. Therefore, affected 
facilities will have both compliant and non-compliant cleaning solvents 
in use. The EPA, therefore, believes it is necessary to ensure that 
cleaning solvents with vapor pressures greater than 45 mm Hg at 20 
deg.C (24.1 in. H2O at 68  deg.F) are only used for the exempted 
cleaning operations. To this end, the EPA is proposing that each owner 
or operator keep daily records of the name and volume of each cleaning 
solvent used in each exempt hand-wipe cleaning operation, as well as 
the parts, assemblies, or subassemblies on which it is used. The EPA is 
requiring daily recordkeeping for these non-compliant solvents so that 
adequate records exist to determine that the solvents are used only in 
the exempt operations.
    The EPA is also proposing that records be kept of each leak found 
when visually inspecting enclosed spray gun systems. These records 
would consist of source identification, the date of discovery of the 
leak, and the date of repair in order to ensure that repairs are 
completed within 15 days as required by the proposed standard.
    For those portions of the cleaning operation standards that require 
containers to be closed when not in use, the EPA is not proposing any 
recordkeeping requirements. Nor is the EPA proposing any recordkeeping 
requirements for the cleaning of spray guns (other than for enclosed 
spray gun cleaners) or flush cleaning.
    b. Primer and topcoat application operations. For all primer and 
topcoat application operations, regardless of which methods are used to 
comply with the proposed standards, the EPA is proposing that each 
owner or operator keep records of the name of each coating and its 
organic HAP and VOC content as received. In addition, the EPA is 
proposing different levels of recordkeeping requirements depending on 
how the organic HAP and VOC content levels are being met. If an owner 
or operator is using compliant coatings to meet the organic HAP or VOC 
content levels, the EPA is proposing that the owner or operator keep 
records that identify for each coating (primer, topcoat) used each 
calendar month, the volume of each coating formulation used each month, 
the masses of organic HAP and VOC emitted per unit volume as applied, 
and the manufacturer's data, calculations, and test results (including 
Method 24 results taken during an enforcement inspection) used to 
determine organic HAP and VOC content of each as applied. Daily records 
are not necessary since, if the coatings are compliant, the emissions 
from the coatings will not exceed the emission limitation in the 
proposed standards on a daily basis. Monthly records, however, are 
necessary to maintain a check that compliance is being maintained.
    If an owner or operator elects to meet the organic HAP or VOC 
content level by averaging, the EPA is proposing that records of the 
daily volume-weighted average organic HAP and VOC contents for primers 
and topcoats be kept as well as all of the data and calculations used 
to calculate these values. This would include the volume, organic HAP 
content as applied, and VOC content as applied of each coating. This 
level of information is required for an inspector to determine whether 
the facility was in compliance and whether the proper data and 
calculations were being used.
    If a control device is used, each owner or operator would be 
required to keep a record (or, where allowed in the proposed standards, 
daily averages) of the various control device operating parameters 
being monitored. Since for some control devices compliance with the 
proposed standards is dependent on the control device being operated 
properly, these records are necessary to determine compliance. 
Specifically, a source would be out of compliance if the recorded 
parameters were out of range. As noted earlier, for incinerators, this 
would be continuous records of the operating temperature(s), while no 
operating parameters are required for carbon adsorbers. Thus, the EPA 
is requiring these records for compliance determinations.
    The recordkeeping requirements for inorganic HAP emissions from 
primers and topcoats, which require recording of the pressure drop 
across the filters or waterwash once per shift during which coating 
operations occur, were included to provide a means of obtaining data 
that can be used to verify that the pressure drop limits are not being 
exceeded. The records can also be used by the facility to determine 
when preventative maintenance should be performed on the filter or 
waterwash system. The proposed rule would also require that the log 
include the pressure drop operating range as specified by the 
manufacturer so that the compliance information is readily available at 
all times.
    c. Depainting operation. For compliance with the standard of no 
organic HAP emissions through the use of chemical strippers that 
contain no organic HAP, the minimum records identified were the name of 
each chemical stripper used in depainting operations, the organic HAP 
content of each stripper, and its supporting documentation.
    The proposed standards contain an exemption for spot stripping and 
decal removal that is based on an annual average volume of organic HAP-
containing stripper per aircraft. To ensure that this exemption is 
being complied with, the EPA is proposing that the owner or operator of 
an affected source record these annual averages. Consequently, records 
must be maintained of the number of aircraft depainted, the volume of 
organic HAP-containing stripper used for spot stripping and decal 
removal, the average number of gallons of organic HAP-containing 
chemical stripper used per aircraft, and all supporting data and 
calculations.
    Similarly, the proposed standards have an exemption for radomes and 
parts depainting. While radomes are self-evident, the parts normally 
removed are not. Therefore, the EPA is proposing that each owner or 
operator keep an up-to-date list of all aircraft depainted at the 
facility and a list of all parts normally removed prior to depainting 
from each aircraft model.
    The EPA believes that it is necessary to ensure that, if a 
depainting facility uses organic HAP-containing chemical strippers, 
they only be used on spot stripping, decal removal, radomes and parts. 
Tracking the daily use of the organic HAP-containing chemical strippers 
by volume would indicate whether or not these strippers are being used 
on the aircraft body. The amount of stripper required to depaint an 
aircraft body is substantially higher than for the exempted operations. 
Therefore, an accounting of stripper usage is necessary to ensure 
organic HAP-containing stripper is not being used on the aircraft body. 
The EPA considered requiring records of the usage of both strippers 
that contain organic HAP and those that do not contain organic HAP be 
maintained. However, the EPA believes that requiring records of both 
types of stripper usage would be overly burdensome to the industry and 
that adequate accounting would be obtained from the usage of organic 
HAP-containing chemical stripper. In addition, records of the usage of 
organic HAP-containing strippers are already being required for spot 
stripping and decal removal. Consequently, the EPA is proposing that 
records be kept only of the organic HAP-containing chemical stripper 
usage.
    Daily recordkeeping of the usage of these strippers was considered 
to be unnecessary since the intent of the records is to show long-term 
trends. Annual records, on the other hand, would require too long of a 
period to establish these trends. Consequently, the EPA is requiring 
monthly records of the organic HAP-containing stripper usage.
    Whenever non-chemical depainting techniques are being used, the 
proposed standards would require that during periods of malfunction, 
alternate depainting methods be used for no more than 14 consecutive 
days unless the alternative method contains no organic HAP. In order to 
determine compliance with these requirements, records must be kept on 
the dates the malfunction occurred and was corrected, the methods used 
to depaint the aerospace vehicles during the malfunction, and the dates 
that these methods were begun and discontinued.
    For inorganic HAP emissions, records of the daily pressure drop 
readings are necessary to ensure that the requirements of the proposed 
standards are being met. The rationale for this requirement is 
identical to that presented for primers and topcoats. In addition, 
records must be maintained of the manufacturer's recommended pressure 
drop limits, the particulate filter control efficiency, and all test 
results, data, and calculations used in determining the control 
efficiency so that compliance determinations can be made.
    d. Chemical milling maskant operation. For the organic HAP and VOC 
content levels, the EPA is proposing different levels of recordkeeping 
requirements depending on how the organic HAP and VOC content levels 
are being met. The selection of and rationale for these recordkeeping 
requirements are identical to those presented above for primers and 
topcoats. In addition, where carbon adsorbers are used to control 
organic HAP and VOC emissions from chemical milling maskants, the same 
recordkeeping requirements as discussed for primer and topcoat 
application operations are being proposed, and the rationale is the 
same.
    e. Handling and storage of waste. Since the proposed standards 
would exempt RCRA wastes, it is necessary to identify which wastes are 
subject to RCRA and which are subject to the proposed rule. Therefore, 
the EPA is proposing that each owner or operator keep an up-to-date 
list of which wastes are subject to RCRA requirements and which are 
subject to the proposed rule, and to keep on file the documentation 
supporting these determinations.
    The EPA received a comment requesting that records be maintained of 
the quantity and type of solvents stored and disposed, as well as the 
disposal facility (if applicable). The purpose of these records would 
be to ensure that the wastes are not improperly disposed since the 
wastes may not be RCRA listed wastes (and, thus, not subject to 
applicable RCRA recordkeeping requirements). The EPA is requesting 
additional comments concerning the addition of these recordkeeping 
requirements. The comments should address whether there are any wastes 
that contain HAP that are not subject to RCRA and, if so, whether the 
recordkeeping requirements under these standards should apply to all 
affected waste streams or only non-RCRA listed waste streams. In 
addition, the comments should address what burden these requirements 
would impose.
2. Reporting Requirements
    In addition to the specific reporting requirements described below 
for each affected source, the proposed rule adopts the provisions 
specified in Sec. 63.9(a) through Sec. 63.9(e) and Sec. 63.9(h) through 
Sec. 63.9(j) and Sec. 63.10 (a), (b), (d), and (f) of the General 
Provisions, 40 CFR part 63, subpart A.12 However, certain time 
periods specified in these sections were changed as detailed in Section 
II.F of this preamble. These time periods were changed in order to 
provide additional time for the EPA to review requests for changes to 
time periods for submittal of reports and for owners or operators to 
respond to EPA requests. These were the only paragraphs from these 
sections (i.e., Sec. 63.9 and Sec. 63.10) that were considered to be 
applicable to the proposed rule.
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    \1\2Ibid.
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    The proposed rule would require an owner or operator to submit the 
following four types of reports:
    (1) Initial notification,
    (2) Notification of compliance status,
    (3) Periodic reports, and
    (4) Other reports.
    The purpose and contents of each of these reports are described in 
this section. The wording of the proposed rule requires all reports to 
be submitted to the ``Administrator.'' The term Administrator refers 
either to the Administrator of the EPA, an EPA regional office, a state 
agency, or another authority that has been delegated the authority to 
implement this rule. In most cases, reports will be sent to state 
agencies. Addresses are provided in the General Provisions of 40 CFR 
part 63, subpart A.13
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    \1\3Ibid.
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    Records of reported information and other information necessary to 
document compliance with the regulation are required to be kept for 5 
years. Per the General Provisions, the 2 most recent years must be kept 
on-site; the other 3 years may be kept off-site. Records pertaining to 
the design and operation of the control and monitoring equipment must 
be kept for the life of the equipment.
    a. Initial Notification. The proposed standards would require 
owners or operators who are subject to this subpart to submit an 
initial notification. As outlined in the General Provisions, 40 CFR 
63.9, this report serves two basic purposes: (1) Notifies the EPA that 
an existing facility is subject to the proposed standards and (2) 
notifies the EPA of the construction of a new facility.14 A 
respondent must also report any facility modifications as defined in 
Sec. 63.5. This report will establish an early dialogue between the 
source and the regulatory agency, allowing both to plan for compliance 
activities. The notice is due no later than 12 months before the final 
compliance date as specified in the proposed standards. Under the 
proposed rule, the initial notification is not required from any source 
that has submitted a permit application under title V of the Act, 
provided that the permit application has been submitted by the same due 
dates as for the initial notification and that the state to which the 
permit application has been submitted has a permit program in place and 
has received delegation of authority from the EPA.
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    \1\4Ibid.
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    As called for by the General Provisions, each owner or operator of 
an affected source would be required to submit a start-up, shut-down, 
and malfunction plan. This plan would be submitted with the initial 
notification.
    b. Notification of Compliance Status. As adopted through the 
General Provisions, owners or operators who are subject to this subpart 
would be required to submit a notification of compliance status. This 
report contains the information necessary to demonstrate that 
compliance has been achieved, such as the results of performance tests, 
Method 24 tests, and design analyses, as well as the methods that will 
be used for determining continuing compliance as outlined in the 
General Provisions, 40 CFR 63.9.15 Another type of information to 
be included in the notification of compliance status is the specific 
range of each monitored parameter for each affected source, the 
rationale for why this range indicates compliance with the emission 
standard, and whether each source has operated within its designated 
operating parameters. The report would be due within 150 days after the 
final compliance date as specified in the General Provisions.
---------------------------------------------------------------------------

    \1\5Ibid.
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    Although not specified in the proposed rule, a description of 
information specific to the aerospace industry that should be contained 
in the initial compliance notification for each of the affected sources 
was presented earlier in this preamble (see Section II.B.2, Reporting 
Requirements). The information presented in that section is not 
necessarily exhaustive.
    c. Periodic Reports. The EPA is proposing to adopt a standard basis 
for submitting periodic reports for each of the operations for which 
standards are being proposed. Semiannual reports would be required 
whenever an operation was found to be in non-compliance or whenever a 
monitored parameter exceeded its value. For example, for a primer 
application operation where averaging is used, a semiannual report 
would be triggered for any daily period covered by the semiannual 
report in which the daily primer volume-weighted average organic HAP 
content limit was exceeded.
    Semiannual reports would also be required whenever a change 
occurred at a facility that might affect a source's compliance status 
or that introduces a new element to the operation that was required to 
be reported in the notification of compliance status. For example, 
reformulation of a chemical milling maskant may change the organic HAP 
content of the maskant. If the HAP content increases, then the owner or 
operator may have to average different or additional chemical milling 
maskants together, or add a control device in order to maintain 
compliance. This change in compliance status would trigger a semiannual 
report.
    For operations that did not experience any exceedances or changes, 
the EPA is proposing that annual reports be submitted to this effect. 
In addition, annual reports are required where compliance is determined 
on an annual basis and exceedances of these annual limits occur.
    The EPA is proposing to adopt the above schedule of reporting 
because it provides a fair balance between the need to know certain 
information in a timely fashion and reduces the burden to industry and 
provides consistency within this regulation. The following paragraphs 
discuss in more detail the specific types of information to be included 
in these various periodic reports. The information being requested is 
that which the EPA believes is necessary in the enforcement of the 
proposed rule.
    (1) Cleaning operation. Periods of non-compliance would be 
transmitted to the EPA in a semiannual report. An example of non-
compliance for hand-wipe cleaning is the use of a cleaning solvent with 
a vapor pressure greater than 45 mm Hg (24.1 in. H2O at 68  deg.F) 
and does not conform to the approved composition list in a nonexempt 
cleaning operation. In addition, any instance where a leaking enclosed 
spray gun cleaner is not repaired within 15 days would be considered an 
instance of non-compliance that would trigger a semiannual report.
    The EPA is also proposing a semiannual reporting requirement if 
changes, such as the use of new cleaning solvents, previously reported 
cleaning solvents no longer in use, or new cleaning techniques for 
spray guns, are made to the cleaning operations at the facility. Where 
a new or reformulated cleaning solvent is used, the semiannual report 
would include documentation of its vapor pressure or documentation that 
it conforms to the approved composition list.
    If the cleaning operation has been in compliance for the annual 
period, then an annual report would be required occurring every 12 
months from the date of the initial report stating that the cleaning 
operation has been in compliance with the applicable standards.
    (2) Primer, topcoat, and chemical milling maskant application 
operations. A semiannual report would be required whenever an 
exceedance of organic HAP or VOC content levels occurred, as well as 
any time a primer or topcoat application operation was not immediately 
shut down when the pressure drop across the filters or waterwash was 
out of range. Where control devices are used to comply with the organic 
HAP or VOC content levels, the EPA is also proposing to require 
semiannual reporting whenever a monitored parameter falls outside its 
appropriate range. Such situations indicate noncompliance with the 
proposed standards.
    If no exceedances occur, each owner and operator would submit 
annual statements indicating that each affected facility has been in 
compliance. The annual reports for primer and topcoat operations would 
also identify the number of times, if any, the pressure drop limits for 
each filter or waterwash system were exceeded.
    (3) Depainting Operations. If new non-chemical depainting 
techniques are introduced to the facility since the filing of the 
notification of compliance status or any subsequent semiannual report, 
the EPA is proposing semiannual reports to identify these techniques. 
The semiannual report would be required to identify any period of 
malfunction of non-chemical depainting methods and techniques and any 
period where the non-chemical depainting operation was not immediately 
shut down when the pressure drop across the filters was out of range.
    For periods of malfunction of non-chemical depainting methods, 
semiannual reports would be required that identify the method or 
technique that malfunctioned, the date that the malfunction occurred 
and was corrected, a description of the malfunction, the alternative 
method(s) used for depainting during the period of malfunction, and the 
date(s) that the methods were begun and discontinued. This information 
is necessary so that adequate documentation is available to ascertain 
whether malfunctions were repaired within the 15 day limit.
    In addition, the facility would be required to report on a 
semiannual basis any new chemical strippers or changes to existing 
formulations and the organic HAP content of each. A semiannual report 
would also be required for each 24-hour period where organic HAP were 
emitted from the depainting operation, other than from spot, radome, or 
parts stripping or decal removal.
    Finally, the semiannual report would be required to identify all 
changes in the type of aircraft depainted at the facility and to 
identify the parts normally removed for depainting separate from the 
aircraft for each new type of aircraft depainted. This is important 
because of the exemption being proposed for radomes and parts that are 
normally removed prior to depainting the aircraft.
    If the depainting operation has been in compliance for the annual 
period, then an annual report would be required stating that the 
depainting operation has been in compliance with the applicable 
standards. An annual report would also be required whenever the 
calculated annual average volume of organic HAP-containing strippers 
used per aircraft for spot stripping and decal removal exceeded the 
applicable limits. The annual report would also report the number of 
times the pressure drop across the particulate filters used for the 
control of inorganic HAP emissions from non-chemical depainting 
operations exceeded the limits specified by the manufacturer.
    (4) Handling and storage of waste. As discussed earlier, since an 
exemption exists for RCRA-regulated wastes, it is important to know 
which wastes are subject to RCRA and which are not. Since facilities 
undergo change over time, it is possible that these designations may 
change. Further, new waste streams may be created. Therefore, 
semiannual reports are being proposed to track changes in the RCRA 
status of existing wastes and new wastes. An annual report would be 
required if no changes occurred in the RCRA status to the existing 
waste streams and if no new waste streams were generated.
    d. Other Reports. The only ``other reports'' in the proposed rule 
are those that are required under the General Provisions, subpart A of 
40 CFR part 63.16 Of particular note is the report required in 
response to periods of startup, shutdown, and malfunction. When the 
procedures used during such periods are completely consistent with the 
plan, a report stating such is to be delivered or postmarked by the 
thirtieth (30th) day following the end of each calendar half. If the 
procedures are not completely consistent with the plan, an owner or 
operator is to report the actions taken within 2 working days after 
commencing actions inconsistent with the plan, followed by a letter 
within 7 working days after the end of the event. The EPA is proposing 
that for non-chemical depainting malfunctions only, that the owner or 
operator report any plan inconsistency for dealing with the malfunction 
within 24 hours after the inconsistent depainting technique is actually 
utilized. This is different from ``after the end of the event'' because 
owners or operators may be able to adjust their depainting schedule to 
accommodate the time to repair a malfunction without the need to 
implement their malfunction plan.
---------------------------------------------------------------------------

    \1\6Ibid.
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I. Selection of Compliance Deadlines

    The EPA proposes to allow affected sources the following time 
periods after promulgation for compliance, as provided for in section 
112(i) of the Act. All sources, whether uncontrolled or having in place 
control systems or measures requiring upgrading to meet the new rule, 
would be required to reach full compliance within 3 years after 
promulgation of the rule. In addition, all affected sources must comply 
with the compliance dates specified in Sec. 63.6 (b) and (c) of the 
General Provisions, 40 CFR part 63, subpart A.17
---------------------------------------------------------------------------

    \1\7Ibid.
---------------------------------------------------------------------------

    The EPA considered requiring earlier compliance to some parts of 
the proposed standards. However, comments received from state agencies 
indicated that there would be far less burden enforcing the standards 
if there was a single compliance date. Multiple compliance dates would 
make it difficult for agencies in states with numerous sources to keep 
track of which standards applied to each facility and when compliance 
would have to begin.
    The EPA recognizes the need for the full three-year period for 
facilities to come into compliance due to the nature of testing and 
qualification necessary for sources such as hand-wipe cleaning 
solvents, primers, topcoats, and chemical milling maskants. For all 
these reasons, the EPA is proposing that all sources be allowed up to 
three years after the date of promulgation of the rule to achieve 
compliance.
    The EPA is requesting comments, however, concerning alternative 
compliance dates for certain pollution prevention and housekeeping 
measures. Specifically, the EPA is considering a compliance date of 90 
days after the effective date of the proposed standards for the 
cleaning operation housekeeping measures in Sec. 63.744(a) of the 
proposed rule, the use of enclosed containers for flush cleaning 
solvents in Sec. 63.744(d), and the provisions for handling and storage 
of waste in Sec. 63.748. The EPA is also considering a compliance date 
of 180 days after the effective date of the proposed standards for the 
spray gun cleaning provisions in Sec. 63.744(c).

J. Operating Permit Program

    Under 40 CFR part 70, all major sources of HAP will be required to 
obtain an operating permit. Emission limits, monitoring, and reporting 
and recordkeeping requirements are typically scattered among numerous 
provisions of State implementation plans (SIP's) or Federal 
regulations. As discussed in the rule for the operating permit program, 
this new permit program would include in a single document all of the 
requirements that pertain to a single source. Once a state's permit 
program has been approved, each aerospace facility that is a major 
source within that state must apply for and obtain an operating permit. 
If the state wherein the aerospace facility is located does not have an 
approved permitting program, the owner or operator of an aerospace 
facility must submit a part 71 permit application if requested under 40 
CFR part 71.

K. Solicitation of Comments

    The Administrator welcomes comments from interested persons on any 
aspect of the proposed standards, and on any statement in the preamble 
or the referenced supporting documents.
    The proposed standards were developed on the basis of information 
available. The Administrator is specifically requesting factual 
information that may support either the approach taken in the proposed 
standards or an alternate approach. To receive proper consideration, 
documentation or data should be provided.

VI. Administrative Requirements

A. Public Hearing

    A public hearing will be held, if requested, to discuss the 
proposed standards in accordance with section 307(d)(5) of the Act. 
Persons wishing to make an oral presentation on the proposed standards 
for aerospace manufacturing and rework should contact the EPA at the 
address given in the ADDRESSES section of this preamble. Oral 
presentations will be limited to 15 minutes each. Any member of the 
public may file a written statement before, during, or within 30 days 
after the hearing. Written statements should be addressed to the Air 
and Radiation Docket and Information Center address given in the 
ADDRESSES section of this preamble, and should refer to Docket No. A-
92-20.
    A verbatim transcript of the hearing and any written statements 
will be available for public inspection and copying during normal 
working hours at the EPA's Air and Radiation Docket and Information 
Center in Washington, DC (see ADDRESSES section of this preamble).

B. Docket

    The docket is an organized and complete file of all the information 
submitted to or otherwise considered by the EPA in the development of 
this proposed rulemaking. The principal purposes of the docket are: (1) 
To allow interested parties to readily identify and locate documents so 
that they can intelligently and effectively participate in the 
rulemaking process, and (2) to serve as the record in case of judicial 
review (except for interagency review materials) (section 307(d)(7)(A) 
of the Act).

C. Executive Order 12866

    Under Executive Order 12866 (58 FR 61736 (October 4, 1993)), the 
EPA must determine whether the regulatory action is ``significant'' and 
therefore subject to Office of Management and Budget (OMB) review and 
the requirements of the Executive Order. The Order defines 
``significant regulatory action'' as one that is likely to result in a 
rule that may:
    (1) Have an annual effect on the economy of $100 million or more or 
adversely affect in a material way the economy, a sector of the 
economy, productivity, competition, jobs, the environment, public 
health or safety, or state, local, or tribunal governments or 
communities,
    (2) Create a serious inconsistency or otherwise interfere with an 
action taken or planned by another agency,
    (3) Materially affect the budgetary impact of entitlements, grants, 
user fees, or loan programs or the rights and obligations of recipients 
thereof, or
    (4) Raise novel legal or policy issues arising out of legal 
mandates, the President's priorities, or the principles set forth in 
the Executive Order.
    Pursuant to the terms of Executive Order 12866, OMB has made the 
determination that this action is not a ``significant regulatory 
action'' within the meaning of the Executive Order. For this reason, 
this action was not submitted to OMB for review.

D. Paperwork Reduction Act

    The information collection requirements in this proposed rule have 
been submitted for approval to OMB under the Paperwork Reduction Act, 
44 U.S.C. 3501 et seq. An Information Collection Request (ICR) document 
has been prepared by the EPA (ICR No. 1687.01) and a copy may be 
obtained from Ms. Sandy Farmer, Information Policy Branch, EPA, 401 M 
St., SW, (2136), Washington, DC 20460 or by calling (202) 260-2740.
    The public reporting burden for this collection of information is 
estimated to average 366 hours per respondent for the first year after 
the date of promulgation of the rule, including time for reviewing 
instructions, searching existing data sources, gathering and 
maintaining the data needed, and completing and reviewing the 
collection of information.
    Send comments regarding the burden estimate or any other aspect of 
this collection of information, including suggestions for reducing this 
burden, to Chief, Information Policy Branch, 2136, U.S. Environmental 
Protection Agency, 401 M St., SW., Washington, DC 20460; and to the 
Office of Management and Budget, Washington, DC 20503, marked 
``Attention: Desk Officer for the EPA.'' The final rule will respond to 
any OMB or public comments on the information collection requirements 
contained in this proposal.

E. Regulatory Flexibility Act

    The Regulatory Flexibility Act (5 U.S.C. 601 et seq.) requires the 
EPA to consider potential impacts of proposed regulations on small 
``entities.'' Since the proposed rule applies only to major sources as 
defined in section 112(a) of the Act, the EPA certifies that there 
would not be a significant impact on a substantial number of small 
entities. Consequently, a regulatory flexibility analysis is not 
required.

F. Clean Air Act Section 117

    In accordance with section 117 of the Act, publication of this 
proposal was preceded by consultation with appropriate advisory 
committees, independent experts, and Federal departments and agencies. 
The Administrator welcomes comment on all aspects of the proposed 
regulation, including health, economic, technological, or other 
aspects.

G. Regulatory Review

    In accordance with sections 112(d)(6) and 112(f)(2) of the Act, 
this regulation will be reviewed within 8 years from the date of 
promulgation. This review may include an assessment of such factors as 
evaluation of the residual health risk, any overlap with other 
programs, the existence of alternative methods, enforceability, 
improvements in emission control technology and health data, and the 
recordkeeping and reporting requirements.

List of Subjects in 40 CFR Part 63

    Air pollution control, Environmental protection, Hazardous 
substances, Reporting and recordkeeping requirements.

VII. Statutory Authority

    The statutory authority for this proposal is provided by sections 
101, 112, 114, 116, and 301 of the Clean Air Act, as amended; 42 
U.S.C., 7401, 7412, 7414, 7416, and 7601.

    4Dated: May 25, 1994.
Carol M. Browner,
Administrator.
[FR Doc. 94-13561 Filed 6-3-94; 8:45 am]
BILLING CODE 6560-01-P