&EFA
          United States
          Environmental Protection
          Agency 	
                Office of Air Quality
                Planning and Standards
                Research Triangle Park NC 27711
EPA-453/R-94-021
December 1995
          Air
Air Emissions from
Municipal Solid Waste
Landfills - Background
Information for Final
Standards and Guidelines
Final
 EIS

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                                      EPA-453/R-94-021
  AIR EMISSIONS FROM MUNICIPAL
     SOLID WASTE LANDFILLS -
  BACKGROUND INFORMATION FOR
FINAL STANDARDS AND GUIDELINES

       Emission Standards Division
          U.S. Environmental Protection Agency
          Region 5, Library (PL-12J)
          77 West Jackson Boulevard. 12th Floor
          Chicago. It  60604-3590
     U.S. ENVIRONMENTAL PROTECTION AGENCY
           Office of Air and Radiation
      Office of Air Quality Planning and Standards
     Research Triangle Park, North Carolina  27711
               December 1995

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V
(
                                     DISCLAIMER


          This report is issued by the Emission Standards Division of the
          Office of Air Quality Planning and Standards of the*Environmental
          Protection Agency.   Copies of this report are available through
          the Library Services office (MD-35),  U.  S. Environmental
          Protection Agency,  Research Triangle Park, NC 27711, telephone
          919-541-2777 (FTS 629-2777),  or may be obtained for a fee from
          the National Technical Information Service, 5285 Port Royal Road,
          Springfield, VA 22161, telephone 703-487-4650.
                          Publication No. EPA-453/R-94-021
         klk-85\04                          11

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                  ENVIRONMENTAL PROTECTION AGENCY

       Air  Emissions  from Municipal Solid Waste  Landfills—
     Background Information for Final  Standards and Guidelines
                           Prepared by:
/Bruce C.  Jordan                                    (ate)
 Emission Standards Division
 U.  S. Environmental Protection Agency
 Research Triangle Park,  NC  27711

  1.   The standards of performance and emission guidelines limit
      emissions from new and existing municipal solid waste
      landfills that emit over 50 Mg/yr of nonmethane organic
      compounds (NMOC).   Section 111 of the Clean Air Act
      (42  U.S.C.  7411),  as amended,  directs the Administrator to
      establish standards of performance and emission guidelines
      for  any category of source of air pollution that "	 causes
      or contributes significantly to air pollution which may
      reasonably be anticipated to endanger public health or
      welfare."

  2.   Copies of this document have been sent to the following
      Federal Departments:   Office of Management and Budget,
      Commerce,  Interior,  and Energy; the National Science
      Foundation;  and the Council on Environmental Quality.
      Copies have  also been sent to  members of  the State and
      Territorial  Air Pollution Program Administrators;  the
      Association  of Local  Air Pollution Control Officials; EPA
      Regional Administrators; and other interested parties.

  3.   For  additional information contact:
      Ms.  Martha  Smith
      Office of Air Quality Planning and Standards (MD-13)
      U. S.  Environmental Protection Agency
      Research Triangle Park,  NC  27711
      Telephone:   (919) 541-2421

  4.   Copies of this document may be obtained from:
      U. S.  EPA Library  (MD-35)
      Research Triangle Park,  NC  27711
      Telephone:   (919) 541-2777

      National Technical  Information Service (NTIS)
      5285 Port Royal Road
      Springfield,  VA 22161
      Telephone:   (703) 487-4650
klk-85\04

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                        TABLE OF CONTENTS
                                                             Page

LIST OF FIGURES	vii
LIST OF TABLES	viii
ACRONYMS, ABBREVIATIONS, AND MEASUREMENTS UNITS  .  .'\  	  X

CHAPTER

1.0  SUMMARY-	1-1
     1.1  Summary of Standards, Emission Guidelines, and
          Methods	1-2
          1.1.1  Listing Under Section 111 of the  Clean Air
                   Act	1-2
          1.1.2  Applicability	1-4
          1.1.3  Standards for Air Emissions from  Municipal
                 Solid Waste Landfills	1-6
          1.1.4  The Tier System Procedures	1-8
          1.1.5  Compliance   	1-12
          1.1.6  Monitoring	1-14
          1.1.7  Reporting and Recordkeeping  	  1-14
          1.1.8  Design Specifications for Active  Vertical
                   Collection Systems 	  1-17
          1.1.9  Additional Information Specific to the
                   Emission Guidelines  	  1-18
          1.1.10  Method 2E	1-19
          1.1.11  Method 3C	1-21
          1.1.12  Method 25C	1-22
     1.2  Summary of Major Comments and Responses  on the
          Proposed standards and Emission Guidelines   . .  .  1-23
          1.2.1  Response to EPA Solicitation of Comments  .  1-23
          1.2.2  Rationale for Significant Changes to
                   Regulation   	1-29
     1.3  Summary of Impacts of Promulgated Action and
          Alternatives  	  1-48
          1.3.1  Revisions to the Data Base	1-49
          1.3.2  Revisions to the Modeling Methodology  .  .  1-51
          1.3.3  Alternatives to Promulgated Action ....  1-54
          1.3.4  Air Impacts	1-54
          1.3.5  Other Environmental Impacts  	  1-59

2.0  SUMMARY AND RESPONSE TO PUBLIC COMMENTS RECEIVED ON THE
     PROPOSED STANDARDS AND GUIDELINES  	 2-1

     2.1  Introduction	2-1
     2.2  General Comments  	  2-13
          2.2.1  Definitions	2-13
          2.2.2  Wording of the Standards	2-16
     2.3  Selection of the Source Category	  2-19
klk-85\0«                           IV

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                  TABLE OF  CONTENTS  (Continued)

          2.3.1  Statutory  Authority to  Regulate   	   2-19
          2.3.2  Health and Welfare  Concerns   	   2-22
     2.4  Selection of the  Affected  and  Designated
          Facilities	2-27
          2.4.1  Exemptions from Control	2-31
          2.4.2  Selection  of the Tier Default Values  .  .  .   2-40
          2.4.3  Removal of Controls	   2-50
     2.5  Selection of the  Pollutant to  be Regulated  .  .  .   2-52
     2.6  Selection of Best Demonstrated Technology ....   2-55
          2.6.1  Selection  of Best Demonstrated Technology—
                   Passive  Systems  	   2-57
          2..6.2  Selection  of the Emission Rate Cutoff  .  .   2-58
          2.6.3  Requirements for Control Equipment ....   2-61
     2.7  Format of the Standard	2-67
     2.8  Nationwide Impacts  	   2-72
          2.8.1  Cost Impacts	2-76
          2.8.2  Secondary  Air Impacts	2-83
          2.8.3  Cost-Benefit Analysis  	   2-85
     2.9  Monitoring and Testing	2-87
          2.9.1  Monitoring	2-87
          2.9.2  Nitrogen Monitoring  	   2-90
     2.10 Modeling	2-95
     2.11 Test Methods	2-100
          2.11.1  Nonmethane Organic Compound Sampling
                    and Analysis	2-101
          2.11.2  Method 2E	2-105
          2.11.3  Method 3C	2-111
     2.12 Design Specifications 	  2-112
          2.12.1  Collection System  Design  	  .  .  2-114
          2.12.2  Determination of Well-Spacing  	  2-123
     2.13 Operational Standards	2-128
     2.14 Compliance	2-134
          2.14.1  Compliance—Schedule  	  2-136
          2.14.2  Compliance—System Shutdown 	  2-139
          2.14.3  Compliance—System Expansion  	  2-142
     2.15 Recordkeeping and Reporting	2-145
     2.16 Regulatory Overlap  	  2-152
          2.16.1  Superfund Interface 	  2-154
          2.16.2  Prevention of Significant Deterioration
                    Interface	2-155
          2.16.3  Subtitle  D Interface  	  2-161
     2.17 State Program Submittals  	  2-162
     2.18 Policy Issues	2-163
          2.18.1  Consideration of Methane  	  2-163
          2.18.2  Consideration of Energy Recovery  ....  2-167
          2.18.3  Consideration of Materials Separation .  .  2-180
     2.19 Miscellaneous	2-181

3.0  ECONOMIC IMPACTS 	 3-1

     3.1  Overview of Municipal Solid Waste Management  .  .  . 3-2
          3.1.1  Waste Generation 	 3-2

klk-85\04                           V

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                   TABLE OF CONTENTS (Continued)


           3.1.2  Waste Disposal	3-3
           3.1.3  Requirements of Alternatives for
                   Promulgation  	 3-4
      3.2   Characteristics of Affected Landfills   	 3-6
           3.2.1  Design Capacity	3-6
           3.2.2  Control Periods for Affected Landfills . .  3-10
           3.2.3  Control Periods Prior to Closure .'*. . . .  3-13
      3.3   Impacts of the Regulation   	3-13
           3.3.1  Enterprise Costs 	  3-17
           3.3.2  Social Costs   	3-33
           3*3.3  Emissions Reduction and Cost Effectiveness  3-37
      3.4   Costs of Regulations Affecting Landfills  ....  3-45
      3.5   Summary and Conclusions   	3-48
      3.6   References	3-53
klk-85\04                           VI

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                         LIST OF FIGURES

Number                                                        Page

3-1  AFFECTED MODEL LANDFILL:  LENGTH OF CONTROL PERIOD
     UNDER THREE STRINGENCY  LEVELS  	 3-5

3-2  EXPECTED IMPACTS OF COSTS OF REGULATIONS ON MUNICIPAL
     WASTE COMBUSTORS	\ . . .  3-46

3-3  EXPECTED IMPACTS OF COSTS OF REGULATIONS ON SANITARY
     LANDFILLS	3-46
klJc-85\04                          Vll

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                          LIST OF TABLES

Number                                                       Page

1-1  SUMMARY OF COST IMPACTS AND EMISSIONS REDUCTIONS OF
     REGULATORY ALTERNATIVES OF THE NSPS	1-55

1-2  SUMMARY OF COST IMPACTS AND EMISSIONS REDUCTIONS OF
     REGULATORY ALTERNATIVES OF THE EG	1-56

2-1  LIST OF WRITTEN COMMENTERS ON THE PROPOSED
     STANDARDS OF PERFORMANCE FOR MUNICIPAL SOLID WASTE
     LANDFILLS	2-2

2-2  LIST OF PUBLIC HEARING SPEAKERS ON THE PROPOSED
     STANDARDS OF PERFORMANCE FOR MUNICIPAL SOLID WASTE
     LANDFILLS	2-12

2-3  LIST OF WRITTEN COMMENTERS ON THE NOTICE OF
     AVAILABILITY FOR THE PROPOSED STANDARDS OF
     PERFORMANCE FOR MUNICIPAL SOLID WASTE LANDFILLS .... 2-14

3-1  SUMMARY INFORMATION FOR AFFECTED CLOSED AND EXISTING
     LANDFILLS	3-7

3-2  SUMMARY INFORMATION FOR AFFECTED NEW LANDFILLS 	 3-9

3-3  LENGTH OF CONTROL PERIOD FOR AFFECTED CLOSED AND
     EXISTING LANDFILLS 	  3-11

3-4  LENGTH OF CONTROL PERIOD FOR AFFECTED NEW LANDFILLS   .  3-12

3-5  LENGTH OF CONTROL PERIOD PRIOR TO CLOSURE FOR
     AFFECTED EXISTING LANDFILLS  	  3-14

3-6  LENGTH OF CONTROL PERIOD PRIOR TO CLOSURE FOR AFFECTED
     NEW LANDFILLS	3-15

3-7  LENGTH OF CONTROL PERIOD PRIOR TO CLOSURE FOR AFFECTED
     EXISTING LANDFILLS: PRIVATE LANDFILLS ONLY 	  3-16

3-8  NET PRESENT VALUE OF ENTERPRISE COSTS FOR AFFECTED
     CLOSED AND EXISTING LANDFILLS  	  3-18

3-9  NET PRESENT VALUE OF ENTERPRISE COSTS FOR AFFECTED
     NEW LANDFILLS	3-20

3-10 ANNUALIZED ENTERPRISE CONTROL COST PER Mg OF MSW FOR
     AFFECTED EXISTING LANDFILLS  	  3-22

3-11 ANNUALIZED ENTERPRISE CONTROL COST PER Mg OF MSW FOR
     AFFECTED EXISTING LANDFILLS WITH DATE OF CLOSURE BEFORE
     1998:  PRIVATE LANDFILLS ONLY	3-24

                               viii

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                    LIST OF TABLES (Continued)

Number                                                       Page


3-12 ANNUALIZED ENTERPRISE CONTROL COST PER Mg OF MSW FOR
     AFFECTED EXISTING LANDFILLS DATE OF CLOSURE BETWEEN
     1998 AND 2002: PRIVATE LANDFILLS ONLY	%. . .  .  3-25

3-13 ANNUALIZED ENTERPRISE CONTROL COST PER Mg OF MSW FOR
     AFFECTED NEW LANDFILLS 	  3-27

3-14 ANNUALI-ZED ENTERPRISE CONTROL COST PER HOUSEHOLD FOR
     AFFECTED EXISTING LANDFILLS	 .  .  3-29

3-15 ANNUALIZED ENTERPRISE CONTROL COST PER HOUSEHOLD FOR
     AFFECTED NEW LANDFILLS 	  3-30

3-16 NET PRESENT VALUE OF TOTAL RECORDKEEPING COSTS  ....  3-32

3-17 NET PRESENT VALUE OF SOCIAL COSTS FOR AFFECTED CLOSED
     AND EXISTING LANDFILLS 	  3-34

3-18 NET PRESENT VALUE OF SOCIAL COSTS FOR AFFECTED NEW
     LANDFILLS	3-36

3-19 NET PRESENT VALUE OF EMISSIONS REDUCTIONS FOR
     AFFECTED CLOSED AND EXISTING LANDFILLS 	  3-38

3-20 COST EFFECTIVENESS FOR AFFECTED CLOSED AND EXISTING
     LANDFILLS	3-40

3-21 NET PRESENT VALUE OF EMISSIONS REDUCTIONS FOR AFFECTED
     NEW LANDFILLS	3-42

3-22 COST EFFECTIVENESS FOR AFFECTED NEW LANDFILLS   ....  3-44

3-23 SUMMARY OF DIFFERENCES BETWEEN THE PROPOSED RULE AND
     FINAL RULE OPTIONS at the 100 Mg PER YEAR
     STRINGENCY LEVEL 	  3-51
kli-85\04                          IX

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         ACRONYMS, ABBREVIATIONS, AND MEASUREMENT UNITS
Acronyms
AEERL

APCD
AQRV
ASCE
BACT
BAT
BDT
BID
BFI
CAA
GARB
CEM
CERCLA

CFC
CFR
CH4
CO
CO2
CTC
          The EPA Office  of Research  and Development's  Air and
          Energy Engineering Research Laboratory
          air pollution control device
          air quality related value
          American Society of Civil Engineers
          best available  control technology
          best available  technology
          best demonstrated technology
          Background Information Document
          Browning-Ferris Industries
          Clean Air Act
          California Air  Resources Board
          continuous emission monitor
          Comprehensive Environmental Response, Compensation,  and
          Liability Act
          chlorof luorocarbon
          Code of Federal Regulations
          Methane
          nonmethane organic compounds concentration
          carbon monoxide
          carbon dioxide
          Control Technology Center
kUt-85\OA

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   ACRONYMS, ABBREVIATIONS, AND MEASUREMENT UNITS  (CONTINUED)


Acronyms

EG        emission guidelines

EIS       Environmental Impact Statement

EMB       Emission Measurement Branch

EMCON     (company name; not an acronym)

EPA       U. S. Environmental Protection Agency

BSD       Emission Standards Division

EXISCLOS  Data base of landfills opening in 1987 and closing in
          1992

FLM       Federal land manager

FID       flame ionization detector

FR        Federal Register

GC        gas chromatograph

HAP       hazardous air pollutant

HOPE      high density polyethylene

HON       hazardous organic NESHAP

H2O       water

I.e.      internal combustion

IGBP      International Geosphere-Biosphere Programme

ISO       Interim Standard Offer

k         methane generation rate constant, year"1

LAEEM     Landfill Air Emissions Estimation Model

LAER      lowest achievable emission rate

LFG       landfill gas
klk-85\04                          XI

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    ACRONYMS,  ABBREVIATIONS,  AND MEASUREMENT UNITS (CONTINUED)


Acronyms

LLRW      low level radioactive waste

L0        methane generation potential, m3/Mg

MACT      maximum achievable control technology

MIR       maximum individual lifetime risk

MSW       municipal solid waste

MWC       municipal waste combustor

N2        nitrogen

NAAQS     national ambient air quality standard

NAPCTAC   national air pollution control techniques advisory
          committee

NESHAP    national emission standards for hazardous air
          pollutants

NIMBY     not in my backyard

NMOC      nonmethane organic compounds

NOX       nitrogen oxides

NPL       National Priorities List

NPV       net present value  (the value at one point in time of  a
          flow of values across time)

NRC       Nuclear Regulatory Commission

NSPS      new source performance standards

NSR       new source review

NSWMA     National Solid Wastes Management Association

NTIS      National Technical Information Service
klk-85\04
                               xii

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    ACRONYMS,  ABBREVIATIONS,  AND MEASUREMENT UNITS (CONTINUED)

Acronyms
NYSDEC    New York State Department of Environmental Conservation
OAQPS     Office of Air Quality Planning and Standards
OMB       Office of Management and Budget
OSW       Office of Solid Waste
OVA       organic vapor analyzer
°2        oxygen
PCS       polychlorinated biphenyls
PCDD      polychlorinated dibenzo-p-dioxins
PCDF      polychlorinated dibenzo furans
pH        hydrogen-ion concentration
PIC       products of incomplete combustion
PM        particulate matter
PM10      particulate matter smaller than 10 microns
POHC      polycyclic organic hydrocarbon
PSD       prevention of significant deterioration
PVC       polyvinyl chloride
RCRA      Resource Conservation and Recovery Act
RFA       Regulatory Flexibility Analysis
RIA       Regulatory Impact Analysis
RIP       refuse-in-place
ROD       Records of Decision
ROI       radius of influence
kUc-85\04
                               xiii

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    ACRONYMS, ABBREVIATIONS, AND MEASUREMENT UNITS (CONTINUED)



Acronyms


RRF       resource recovery facilities

                                                    • \
SBA       Small Business Act


SCAQMD    South Coast Air Quality Management  District


SDB       Standards Development Branch


SIP       State implementation plan


SC>2       sulfur dioxide


SOX       sulfur oxides


SWANA     Solid Waste Association of North America


TAG       technical advisory group


TCD       thermal conductivity detector


TGNMO     total gaseous nonmethane organics


TOC       total organic carbon


TSDF      treatment, storage and disposal facility


VOC       volatile organic  compound


WMA       Waste Management,  Inc.


WCRP      World Climate Research Programme



Abbreviations and Measurements Units


Btu     = British thermal unit


°C      = degrees Celsius


dscf    = dry standard cubic foot (14.7 psi,  68 °F)


dscm    - dry standard cubic meter (760 mmHg, 20  °C)
kli-85\04
                               xiv

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   ACRONYMS, ABBREVIATIONS, AND MEASUREMENT UNITS  (CONTINUED)

Abbreviations and Measurements Units
°F      = degrees Fahrenheit
ft      - foot
ft3     = cubic foot
in.     = inch
J       — joules
km      = kilometers
In      = natural log
m       = meter
mm      = millimeter
MM      = million
ml/min  = milliliter per minute
Mg      = megagram
MW      = megawatt
m3      = cubic meter
mg      = milligram
ppm     = parts per million
ppmv    = parts per million by volume
ppmvd   = parts per million by volume, dry
psi     = pounds per square inch
tons/yr = tons per year
yr      = year
$/Mg    = dollars per megagram
$/ton   = dollars per ton
kIk-BSW
                                XV

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                            1.0  SUMMARY

       On May  30,  1991, the Environmental Protection Agency
   (EPA) proposed new  source performance standards  (NSPS)  for new
   municipal  solid  waste  (MSW)  landfills and emission guidelines
   (EG) for existing MSW landfills  (56  FR 24468)  under  the
   authority  of sections lll(b) and (d)  of the Clean Air Act
   (CAA).  Public comments were requested on the  proposed
   standards  and guidelines.  Comment letters were  received from
   60  commenters including industry representatives, governmental
   entities,  environmental groups,  and  private citizens.   A
   public hearing was  held in Research  Triangle Park, North
   Carolina,  on July 2, 1991.   This hearing was open to the
   public and five  persons presented oral testimony on  the
   proposed NSPS and EG.
       On June 21, 1993, a  supplemental notice of  data
   availability to  the May 30,  1991 proposal appeared in the
   Federal Register (58 FR 33790).   The notice announced the
   availability of  additional data  and  information  on changes in
   the EPA's  modelling methodology  being used in  the development
   of  the final NSPS and EG  for MSW landfills.  Public  comments
   were requested on the new data and comment letters were
   received from seven commenters.
       Changes have been made  to the NSPS and EG in response to
   comments and as  a result  of  additional analyses  completed
   since proposal.  The final NSPS  and  EG are summarized in
   section 1.1.  The major changes  made to the proposed rules are
   summarized in section 1.2.   A  summary of the impacts of the
   NSPS and EG  is presented  in  section  1.3.  All  of the written
   and verbal comments that  were  submitted regarding the proposed

kli-85\0*                           1-1

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  rules and notice of data availability are summarized in
  chapter 2.  The revised economic impacts analysis is presented
  in chapter 3.  The summary of comments and responses and
  revised economic impacts serve as the basis for the revisions
  made to the NSPS and EG between proposal and promulgation.
  1.1  SUMMARY OF STANDARDS, EMISSION GUIDELINES, AND METHODS
  1.1.1  Listing Under Section 111 of the Clean Air*Act
       Section 111(b)(1)(A) of the CAA provides:

       The Administrator shall, within 90 days after
       [December 31, 1970], publish (and from time to time
       thereafter shall revise) a list of categories of
       stationary sources.  He shall include a category of
       sources in such list if in his judgment it causes,
       or contributes significantly to, air pollution which
       may reasonably be anticipated to endanger public
       health or welfare.

  Section lll(b)(1)(B) requires the Administrator to promulgate
  "standards of performance for new sources within such
  category."
       Concurrently with promulgating the landfills NSPS and EG,
  the Administrator had added the source category MSW landfills
  to the priority list in  40 CFR 60.16 because in the judgment
  of the Administrator it  contributes significantly to air
  pollution which may reasonably be anticipated to endanger
  public health and weliare.
       MSW  landfill emissions, commonly called landfill gas
  (LFG), are generated by  naturally occurring methanogens that
  decompose complex organic materials into organic  compounds of
  lower molecular weight.  Landfill gas consists primarily  of
  carbon dioxide  (C02), methane, and non-methane organic
  compounds  (NMOC).  The methane strips or transports NMOC
  through the  landfill  to  the  atmosphere.  Evidence from the EPA
  and  State studies  indicates  that LFG released  by MSW  landfills
  has  adverse  effects on both  public health  and  welfare.
       The  first  specific  health and welfare effect of  concern
  is ozone  formation.   Ground  level ozone  is created  by sunlight

klk-85\0*                           1-2

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   acting on nitrogen oxides (NOX)  and NMOC in ambient air.
   Ozone may lead to health effects such as alteration of
   pulmonary function,  aggravation  of preexisting respiratory
   disease,  damage to lung structure/  and adverse effects on
   blood enzymes, the central nervous system,  and the endocrine
   system.   Ozone also presents welfare effects such as reduced
   plant growth,  reduced crop yield,  necrosis  of plant tissue,
   and deterioration of certain synthetic materials,  such as
   rubber.
        A second  concern is the cancer and noncancer health
   effects of various NMOC.  Many NMOC identified in LFG are
   either known or suspected carcinogens,  and  have the potential
   to produce noncancer health effects as well,  such as adverse
   effects on the kidneys,  liver, and central  nervous system.
   Many of the NMOC are Hazardous Air Pollutants (HAP's)  as
   defined under  section 112(b)  and listed by  the Source Category
   List under section 112(c) of the CAA,  as amended in 1990
   (57 FR 31576,  July 16, 1992). The EPA intends to evaluate MSW
   landfills as a source category under this section.
        Additional public welfare concerns are odor nuisance from
   gaseous decomposition, and the potential for methane
   migration,  both on-site and off-site,  which may lead to
   explosions or  fires.  Explosive  gas control is already
   addressed under S 258.23 of the  Resource Conservation and
   Recovery Act (RCRA)  Subtitle D rules (40 CFR part 258);
   however,  a landfill gas control  system will significantly
   reduce the explosion potential.   These concerns are not only
   nuisances in and of themselves,  but can adversely affect
   adjacent property values.  And,  as discussed in the preamble
   to the proposal,  MSW emissions contribute to global methane
   emissions,  a major greenhouse gas.   These methane emissions
   also present a welfare concern.
        Although  one commenter suggested that  LFG emissions
   should be regulated under RCRA authority, the EPA continues to
   consider Section 111 NSPS and EG to be the  appropriate
   statutory approach for regulating these emissions because the

kli-85\0*                           1-3

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  adverse health and welfare effects of concern result from air
  emissions.  Therefore, the final notice added MSW landfills as
  a source cat  ory for regulation under Section lll(b)(1)(A) of
  the CAA to th« priority list in 40 CFR 60.16.
  1.1.2  Applicability
       The affected facility under the NSPS is each new MSW
  landfill.  Municipal solid waste landfills are also subject to
  the requirements of RCRA (40 CFR part 258).  A new MSW
  landfill is a landfill for which construction, modification,
  or reconstruction commences on or after the proposal date of
  May 30, 1991 or that began accepting waste on or after that
  date.
       The emission guidelines require control for certain
  exist  g MSW landfills.  An existing MSW landfill is a
  landfill for which construction commenced prior to May 30,
  1991.  An existing MSW landfill may be active, i.e., currently
  accepting waste, or having additional capacity available to
  accept waste, or may be closed, i.e., no longer accepting
  waste nor having available capacity for future waste
  deposition.  The designated facility under the emission
  guidelines  is each existing MSW landfill that has accepted
  waste since November 8, 1987.
       Section 60.752 of the NSPS requires affected and
  designated  MSW  landfills having design capacities below
  2.5 million megagrams  (Mg) or 2.5 million cubic meters  (m3)  to
  file a design capacity report.  Affected and designated MSW
  landfills having design capacities greater than or equal to
  2.5 million Mg  or 2.5 million m3 are subject to the  additional
  provisions  of the standards or guidelines.
       Some changes have been made to the definitions  in  both
  subpart WWW and subpart Cc so that definitions in these
  subparts would  be consistent with definitions in regulations
  of part  258 of  title  40, Criteria for MSW Landfills  Under
  RCRA.
       MSW  landfills are also listed under  section 112(c) as a
  source category (57 FR 31576, July 16,  1992).  Promulgation of

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   section  112  emission standards  for the  MSW landfills source
   category is  currently scheduled for not later than
   November 15,  2000  (58 FR 63941,  63954,  Dec.  3,  1993).
        Section lll(d)(1)(A)  was twice amended by the 1990 Clean
   Air  Act  Amendments.   Pub.  L. 101-549, section 302(a),  directed
   the  substitution of  "7412(b)M for  "7412(b)(1)(A)," and Pub. L.
   101-549,  section 108(g),  substituted "or emitted from a source
   category which is  regulated under  section 7412 of  this title"
   for  "or  7412(b)(1)(A)."   Title  42  of the U.S.  Code adopts the
   amendment* of section 108(g) with the explanation that
   section  302(a)  could not be executed because of the prior
   amendment by section 108(g).  42 U.S.C. section 7411 (Supp.IV
   1993).   The  EPA also believes that section 108(g)  is the
   correct  amendment  because the Clean Air Act Amendments revised
   section  112  to include regulation  of source categories in
   addition to  regulation of listed hazardous air pollutants, and
   section  108(g)  thus  conforms to other amendments of
   section  112.   The  section not adopted by title 42, 302(a), on
   the  other hand,  is a simple substitution of one subsection
   citation for another,  without consideration of other
   amendments of the  section in which it resides,  section 112.
   Thus EPA agrees that CAA section lll(d)(1)(A)  should read
   "[t]he Administrator shall prescribe regulations which . . .
   establish[]  standards of performance for any existing source
   for  any  air  pollutant .  .  . which  is not .  . .  emitted from a
   source category which is regulated under section 112."
        Thus, as amended by the 1990  Clean Air Act Amendments,
   section  lll(d)(1)(A) allows EPA to establish NSPS  without
   prescribing  emission guidelines for existing sources if the
   designated air pollutant is 1)  a pollutant for which air
   quality  criteria have been issued, 2) included on  a list
   published under section  108(a),  or 3) emitted from a source
   category regulated under section 112.   That is not the case
   here because landfill gas, the  designated air pollutant for
   MSW  landfills,  is  not a  pollutant  which satisfies  any of these
   criteria.  First,  landfill gas  is  a composite of many

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  compounds, including some compounds for which air quality
  criteria have been issued and which are included on a list
  published under section 108(a) (e.g. volatile organic
  compounds (VOC), which are ozone precursors), although other
  landfill gas components, such as methane and methylene
  chloride, are not compounds for which air quality criteria
  have been issued and are not included on a list published
  under section 108(a).  Moreover, landfill gas itself is not an
  air pollutant for which air quality criteria have been issued,
  and landfill gas itself is not included on a list published
  under section 108(a).
       Finally, landfill gas is not emitted from a source
  category that is actually being regulated under section 112.
  Although MSW landfills is a source category listed under
  section 112(c), existing MSW landfills will not actually be
  regulated under section 112 until an emission standard is
  proposed under section 112(d).  Because a section 112 emission
  standard for MSW landfills is not scheduled for promulgation
  until the year 2000, MSW landfill emissions will not actually
  be regulated under section 112 until that time.  In addition,
  some components of landfill gas are not hazardous air
  pollutants listed under section 112(b) and thus will not be
  regulated under a section  112(d) emission standard.
  Therefore, EPA is establishing emission guidelines under
  section lll(d)(1)(A) for sources of the designated pollutant
  landfill gas.
  1.1.3  Standards for Air Emissions from Municipal Solid Waste
  Landfills
       The  final standards and  EG for MSW landfill emissions
  require the periodic calculation of the annual NMOC emission
  rate at each affected or designated facility with a maximum
  design capacity greater than  or equal to 2.5 million Mg or
  2.5 million m3.
       The  best demonstrated technology  (BDT)  (for both the NSPS
  and the EG) requires the reduction  of MSW landfill emissions
  from new  and existing MSW  landfills emitting 50 Mg per year

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   (Mg/yr)  of NMOC  or more with:   (1)  a well-designed  and
   well-operated  gas collection system and  (2) a control device
   capable  of reducing NMOC  in the collected gas by
   98 weight-percent.
        A well-designed  and  well-operated collection system
   would, at a minimum:   (1)  be capable of  handling the maximum
   gas  generation rate;  (2)  have  a design capable  of"monitoring
   and  adjusting  the operation of the  system;  (3)  be able  to
   collect  gas effectively from all  areas of the landfill  that
   warrant  control; and  (4)  be able  to expand  by the addition of
   further  collection system components to  collect gas from new
   areas of the landfill as  they  require control.
        The BDT control  device is a  combustion device  capable of
   reducing NMOC  emissions by 98  weight-percent.   While energy
   recovery is strongly  recommended, the cost  analysis is  based
   on open  flares because they are applicable  to all affected and
   designated facilities regulated by  the standards and emissions
   guidelines.  If  an owner  or operator uses an enclosed
   combustion device, the device  must  demonstrate  either the
   98-percent reduction  or reduction of the outlet NMOC
   concentration  to 20 ppmvd as hexane at 3-percent oxygen as
   demonstrated by  Method 25 or Method 18 of appendix  A of 40 CFR
   part 60  (for the compounds listed in the most recent
   "Compilation of  Air Pollutant  Emission Factors" (AP-42)).
   Alternatively, the collected gas  may be  treated for subsequent
   sale or  use, provided that all emissions from any atmospheric
   vent from the  treatment system are  routed to a  control  device
   meeting  either specification above.
        The standards require that three conditions be met prior
   to removal of  the collection and  control system:   (1) the
   landfill must  be permanently closed under the requirements of
   40 CFR 258.60;  (2) the collection and control system must  have
   been in  continuous operation a minimum of 15 years; and
   (3)  the  annual NMOC emission rate routed to the control device
   must be  less than the emission rate cutoff  of 50 Mg/yr  on
   three successive dates, between 90  and 180  days apart,  based

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  upon the site-specific landfill gas flow rate and average NNOC
  concentration.
       A  new section of the regulation, S 60.753, contains
  provisions regarding the operational standards for collection
  and control systems.  These provisions include:
  (1) collection of gas from each active area, cell, or group of
  cells in which non-asbestos degradable solid waste has been
  placed for a period of 5 years or more and from each closed
  area or area at final grade in which solid waste has been
  placed for at least 2 years;  (2) operation of the collection
  system with each wellhead under negative pressure;
  (3) operation with a nitrogen level less.than or equal to
  20 percent or an oxygen level less than or equal to 5 percent;
  (4) operation with a landfill gas temperature less than 55 °C;
  (5) a requirement that the collection system be operated to
  limit the surface methane concentration to less than 500 ppm
  over the landfill;  (6) venting of all collected gases to a
  treatment or control device;  and  (7) operation of the control
  device at all times when the  collected gas is routed to the
  control device.
  1.1.4  The Tier System Procedures
       The tier system is used  to determine if and when an
  affected or designated landfill needs to install a gas
  collection system.  As an example, a relatively new landfill
  may produce landfill gas above the emission rate cutoff at
  some time in the future; the  annual emission estimate in the
  tier calculations will indicate when this time has come.
  Section 60.754 of the NSPS provides the tier system for
  calculating whether the NMOC  emission rate is less than
  50 Mg/yr, using a first order decomposition rate equation.
  Section 60.34c of the EG also requires calculation of the NMOC
  emission rate using the tier  system provided in the NSPS.  Any
  owner or operator that already has or intends to install
  controls  (to full compliance) without modeling the emissions
  does not need to use this tier system.
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        The final  NSPS  and EG allow the mass  of  segregated,  non-
   degradable waste in  a  landfill  to be subtracted  from  the  total
   mass prior to the NMOC emission rate calculation, provided
   that the non-degradable nature  of the waste,  location,  and
   mass are recorded and  included  with the emission rate report.
        Tier 1—Under Tier 1,  the  landfill owner or operator
   combines readily available data such as landfill "age  and  waste
   acceptance rate with default values of 0.05/yr for  the  methane
   generation rate constant (k), 170 m3/Mg for the  methane
   generation potential (L0)  and 4,000 parts  per million by
   volume (ppmv) for the  NMOC concentration.  The default  values
   for these parameters were-changed between  proposal  and
   promulgation.   The default values for k, Lo,  and NMOC
   concentration are within an acceptable range  and were selected
   to  minimize the number of  landfills that are  actually emitting
   more than 50 Mg/yr of  NMOC,  but would be estimated, using the
   default values,  to emit less than the cutoff.  In selecting
   the default values in  this way,  Tier 1 estimates emissions
   from some landfills  to be  greater than the emission rate
   cutoff when in  reality they are not.  Therefore, the  landfill
   can use site-specific  information from Tier 2 and Tier  3  to
   show that the revised  emission  estimates are  below  the  cutoff.
   For those landfills  where  the Tier 1 calculation results  in an
   emission estimate below 50 Mg/yr of NMOC,  the rules would not
   require collection and control  systems, but would require
   periodic recalculation of  emissions until  closure.  For those
   landfills whose Tier l calculations result in an NMOC emission
   rate equal to or greater than 50 Mg/yr, the owner or  operator
   must either install  collection  and control systems  or must
   perform the field measurement procedures detailed in  Tier 2 to
   better estimate the  site-specific NMOC emission  rate  for
   comparison with the  50 Mg/yr cutoff.
        Tier 2—In Tier 2,  the landfill owner or operator
   conducts sampling to determine  a site-specific NMOC
   concentration to substitute for the default NMOC concentration
   of  4,000 ppmv in the Tier  1 equation.  The standards  provide

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  sampling procedures for NHOC concentration,  and the samples
  are to be analyzed using Method 25C.   Unlike the proposal,  the
  number of samples depends on the size of the landfill.   Two
  samples must be taken from each hectare up to a maximum of 50
  samples.  More than 2 per hectare or more than 50 samples may
  be taken; however, all samples taken must be used in the
  analysis.  If the NMOC emission rate calculated Using the
  site-specific NMOC concentration is equal to or greater than
  50 Mg/yr, the owner or operator must install controls or
  perform the field testing procedures detailed in Tier 3 to
  better estimate the NMOC emission rate for comparison with the
  50 Mg/yr cutoff.
       If the average NMOC concentration from the samples
  results in a calculated NMOC emission rate below the emission
  rate cutoff of 50 Mg/yr, the standards require retesting of
  NMOC concentration levels for use in the tier calculations
  every 5 years.  Due to the increase in the design capacity
  exemption and the decrease in the emission rate cutoff, the
  proposed provision for a statistical analysis to allow
  10 years between retesting the NMOC concentration levels has
  been deleted from the final rule.  These changes to the rule
  greatly reduce the number of landfills that would perform
  Tier 2 measurements.  The lower emission rate cutoff will
  require controls to be applied sooner, and the change
  simplifies implementation of the rule.
       Tier 3—Under Tier 3, a site-specific methane generation
  rate constant, k, is determined by gas flow testing to
  substitute for the default k value of 0.05/yr in the equation.
  Tier 3 distinguishes between MSW landfills with known
  histories of where and when MSW was deposited and those with
  little known history.  Cluster wells are used when the history
  is known, and equal-volume wells when the history is not
  known.  Cluster wells are groupings of three wells fairly
  close together, whereas equal-volume wells are evenly spaced
  throughout the  landfill.  For  landfills with known histories,
  Method  2E provides guidance on where to locate cluster wells

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   to  provide good estimates  of  k.  However,  if  landfill history
   is  not known,  the equal-volume well method produces  estimates
   with greater statistical confidence than cluster wells.
   Tier 3 testing is performed using Method 2E,  which is a  final
   method promulgated in the  rule.  The  NSPS  requires that  the
   NMOC concentration obtained in Tier 2 be used in all Tier  3
   calculations.                                    '*
        Landfills where the NMOC emission rate calculated in
   Tier 3 is below 50 Mg/yr need not install  collection and
   control systems,  but must  still  retest the concentration of
   NMOC every 5 years as required in Tier 2.  The value for k
   obtained in Tier 3 is to be used for  all subsequent
   calculations.
        Landfills with a calculated emission  rate greater than
   50  Mg/yr, after substituting  both a site-specific NMOC
   concentration and a site-specific k,  must  install a  collection
   and control system.
        Calculation of NMOC and  Flow for On-Line Collection
   Systems—For landfills which  have a collection system already
   installed,  the standards provide formulas  and procedures for
   calculating NMOC emissions using samples and  gas flow data
   obtained from an existing  collection  system.   These  formulas
   can be used by landfills that are presently collecting
   landfill gas to show that  their  NMOC  emissions are less  than
   the emission rate cutoff.  These formulas  and procedures can
   also be used by landfills  that have installed collection and
   control systems to comply  with the rule when  the emissions
   have subsided to the extent that the  owner or operator would
   like to determine if the NMOC emissions are now less than  the
   emission rate cutoff.  Landfill  owners or  operators  using
   direct sampling would have to demonstrate  that there is  not
   excessive air infiltration into  their system, and that there
   was no positive pressure at any  wellhead when sampling and gas
   flow tests were performed. The  landfill owner or operator
   must also document that the collection system is effectively


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  collecting landfill gas from all gas producing areas of the
  landfill.
       Using samples and gas flow data from an existing system
  is the only method allowed for determining that the NMOC
  emission rate is less than 50 Mg/yr when owners or operators
  want to remove control systems.  The formula and procedures
  for sampling and determining the NMOC concentration and the
  gas flow directly from the system provided in S 60.754(b) of
  the final NSPS must be used when calculating the NMOC emission
  rate for the purpose of system removal.  The tier approach is
  not permitted once a collection system has been installed,
  because direct sampling procedures provide the most accurate
  estimate of the NMOC emission rate and are readily available
  after system installation.
  1.1.5  Compliance
       Section 60.755 of the NSPS provides formula and/or
  procedures for determining compliance with the standards  for
  collection systems and control devices provided in
  S S 60.752(b)(2)(ii) and 60.753.
       To design the collection system to handle the maximum
  expected gas flow rate, the maximum expected gas generation
  rate is calculated using the default values for k and Lo; if
  Method 2E has been performed, the owner or operator must  use
  the site-specific k.  In S 60.755(a)(1) of the final standard,
  changes have been made to allow calculation of the maximum gas
  generation rate  for sites with known and unknown year-to-year
  solid waste acceptance rates, and for a specific intended
  equipment use period, if the owner or operator intends to use
  the equipment for a period of time other than 15 years.
  Section 60.755(a)(2) was revised to allow the use of any
  collection system approved by the regulatory authority capable
  of controlling and extracting gas from all required portions
  of the landfill.  The design plan must demonstrate that there
  is a sufficient  density of gas collectors to meet all
  operational and  performance standards.
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        Section 60.755(a)(3)  requires that  adjustments  to the  gas
   collection header and wellhead valves  be made to maintain
   negative pressure.   A time schedule was  added to this  section
   that requires an additional well  to be installed if  negative
   pressure cannot be achieved within a specified time  period.
        Several commenters maintained that  30  days was  not
   adequate time to establish negative pressure at the  wellhead
   after initial start-up of  the collection and control system.
   Upon further evaluation, the rules were  modified to  allow
   180 days to establish negative pressure  at  the wellhead after
   initial start-up of the collection and control system.
        A new paragraph (a)(6) was added  to S  60.755, requiring
   that owners and operators  of MSW  landfills  seeking to
   demonstrate compliance with the standards for collection
   systems must demonstrate that off-site migration is  being
   controlled.
        As discussed later in the summary of major changes to  the
   rule section,  three additional compliance provisions were
   added to S 60.755.   These  provisions are:   (1) a 60  day time
   limit for the extension of the collection system into  solid
   waste that has reached an  age of  5 years if active,  2  years if
   closed or at final grade [in S 60.755(b)];  (2) procedures and
   instrument specifications  for monitoring surface
   concentrations of methane, including the installation  of
   additional wells, if necessary; and (3)  allowable downtime  for
   start-up,  shutdown and malfunction of  collection or  control
   equipment.  The reader is  directed to  sections 1.2.3.4 through
   1.2.3.6 of this BID for a  discussion of  these provisions.
        Owners and operators  seeking to demonstrate compliance
   with S 60.752(b)(2)(iii) are required  to use open flares
   operated in compliance with 40 CFR 60.18, or to conduct an
   initial performance test using Method  25 or Method 18
   (speciated for compounds listed in AP-42) to demonstrate
   either 98 percent NMOC emission reduction or, for enclosed
   combustors,  a concentration of 20 ppmvd  NMOC as hexane at
   3  percent oxygen at the outlet.

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  1.1.6  Monitoring
       Each MSW landfill installing a collection system must
  monitor the nitrogen or oxygen concentration and the
  temperature of the LFG at each well on a monthly basis.  Also,
  the owner or operator can propose and use an alternative
  method for detecting infiltration (such as monitoring for
  carbon monoxide, the methane to carbon dioxide ra£io, or the
  composting ratio) provided that the method is approved by the
  permitting authority.
       When an enclosed combustion device is used for control,
  the temperature and the gas flow to (or bypass of) the control
  device must be monitored.  When an open flare is used for gas
  control, the pilot flame (or flare flame itself) must be
  monitored using a heat sensing device to demonstrate the
  continuous presence of a flame, and the gas flow to  (or bypass
  of) the control device must be monitored.
       Sections 60.756(d) and (e) provide that for each
  collection system and for any control device other than an
  open flare or an enclosed combustion device used, the owner or
  operator must provide to the regulatory authority information
  describing the operation of the system and/or device,
  parameters that would indicate proper performance and
  monitoring procedures.
  1.1.7  Reporting and Recordkeepina
       The final standards require owners and operators of all
  affected facilities to submit notifications of construction,
  modification, or reconstruction as required under the General
  Provisions  (40 CFR 60.7).  This notification must include the
  maximum design capacity of the landfill, date of anticipated
  initial waste acceptance, and the anticipated solid  waste
  acceptance rate.  The EPA expects that the design capacity
  calculation required in the notification of construction
  report will exclude  a large majority of all landfills  from  the
  further provisions of the standards, and will alert
  enforcement personnel to the remaining population of landfills
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   that may be required to install  collection  and  control  systems
   in  the future.
        Notification of construction  from HSV  landfills with
   initial design  capacities  less than  2.5 million Mg  or
   2.5 million m3  fulfills all  of the recordkeeping and reporting
   requirements for these  landfills unless the design  capacity is
   revised above the limit in the future.           x
        Each owner or operator  of an  MSW landfill  with a design
   capacity equal  to or greater than  2.5 million Mg or
   2.5 million m3  must install  a collection and control system or
   submit an annual calculation demonstrating  that the NMOC
   emission rate is less than 50 Mg/yr.  Alternatively, the owner
   or  operator could elect to provide an estimate  of the NMOC
   emission rate for each  of  the next 5 years  using the equations
   provided in § 60.754 and an  estimate of the solid waste
   acceptance rate for each of  the  5  years, provided that  the
   estimated NMOC  emission rate does  not exceed 50 Mg/yr in any
   of  the 5 years  reported.   The initial annual NMOC emission
   rate report or  5-year estimate must  be submitted within
   90  days of start-up, i.e., solid waste acceptance.
        The owner  or operator must  also update and re-submit  the
   5-year estimate within  at  least  5  years of  submittal of the
   first 5-year estimate.   Additionally, if the actual waste
   acceptance rate exceeds the  estimated waste acceptance  rate in
   any of the 5 years for  which an  estimated NMOC  emission rate
   was reported, a revised estimate must be submitted. The
   5-year period reported  in  the revised 5-year estimate would
   commence when the new report is  submitted.
        After the  NMOC emission rate  calculated using  Tier 1
   equals or exceeds 50 Mg/yr,  § 60.757(c) of  the  final standards
   requires the submission of a collection and control system
   design plan for approval within  a  year.  A  landfill owner  or
   operator may elect to perform the  Tier 2 sampling or Tier  3
   testing to generate a site-specific  NMOC concentration  or  gas
   generation rate to use  for the calculation  of a more accurate
   NMOC emission rate.   In either case,  the recalculated emission

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  rate must be reported within 1 year of the initial Tier 1
  calculation as well.  If the recalculated emission rate still
  equals or exceeds 50 Mg/yr, the collection system design plan
  must also be submitted within the same 1-year time period in
  which the Tier 1 calculation equaled or exceeded 50 Mg/yr.
       After the 1-year described above, a landfill will have
  18 months to install an approved collection system.
  Collection system design plans should require 180 days for
  review and revision; therefore, 1 year is allowed for
  installation of the collection system.  As discussed in the
  proposal preamble, the EPA believes this approach to be fair
  for either design approach (see proposal preamble section
  III.H).  An owner or operator using an approved design is
  allowed an additional 180 days to submit the initial
  performance test.
       After the collection and control system has been
  installed and the initial performance test has been completed
  and submitted, S 60.757(f) of the NSPS and S 60.35C of the EG
  require the submission of annual compliance reports which
  include:   (1) any period in which the value of any of the
  monitored operating parameters falls outside the acceptable
  ranges;  (2) all periods when the gas stream was diverted from
  the control device;  (3) periods when collection or control
  equipment was not operating;  (4) the location of all
  exceedances of the  500 ppm methane limit during the quarterly
  surface monitoring  and the highest level recorded at that
  location in the subsequent monitoring period; and  (5) the date
  of installation and location of each well added to the system
  during the period.
       The NSPS and EG also require that certain types of
  records be maintained.  Records of the accumulated solid waste
  in place, collection system design  (including planned as well
  as current well or  trench  layout), control device vendor
  specifications, the initial and most recent performance test
  results, and the monitoring parameters established during the
  initial performance test must  be maintained as long as the

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   collection system and control  devices  are  required to be
   operated.
       Any replacement  of  system components  which results in  a
   change  in  the  level of any  parameter that  is monitored to
   demonstrate 98 percent NMOC destruction  efficiency must be
   entered into this permanent record, and  reported  in  the next
   annual  compliance report.   Monitoring  records  and"all data  and
   calculations from each annual  compliance report must be
   maintained for at least  5 years following  the  date of such
   reports. '
   1.1.8   Design  Specifications for Active  Vertical  Collection
   Systems
       In the final standards, provisions  are given that design
   plans must specify methods  for siting  active vertical
   collection wells  throughout the landfill,  but  does not contain
   prescriptive design plans.   Instead, all site-specific design
   plans must be  approved by the  Administrator  (in most cases  the
   State or local regulatory agency will  be delegated authority
   to  implement the  NSPS and EG,  including  the approval of design
   plans). Wells must be placed  so that  gas  is collected from
   all active areas  of the  landfill that  have contained solid
   waste for  at least 5  years  and all  closed  areas or areas  at
   final grade that  have contained solid  waste for at least
   2 years.
       The final standards have  been  changed to  allow  the owner
   or  operator to consider  the site-specific  equipment  life  when
   sizing  the collection system blower.   In this  way, blowers  may
   be  used over shorter  periods of time or  exchanged to more
   closely track  gas flow rate without being  out  of  compliance.
   The formula for determining maximum flow rate  has been revised
   to  accommodate both active  and closed  landfill conditions.
       The final NSPS distinguishes between  areas that are
   nonproductive  because of the age of the  solid  waste  and those
   that are non-degradable  due to the  inorganic nature  of the
   solid waste when  allowing such areas to  be excluded  from  the
   collection system.  Nonproductive areas  are excluded due  to

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  low NMOC emissions, and all such excluded areas must
  collectively contribute less than 1 percent of total NMOC
  emissions.  Non-degradable areas are excluded because they
  have no emission potential, and only if (1) such materials are
  deposited in a segregated area not overlying productive solid
  waste, and (2) the location, volume, mass and nature of the
  excluded materials are documented and reported.
       The final EG requires that existing landfills subject to
  control must install collection systems that meet the MSPS
           •
  standards for collection systems.  The collection system must
  satisfy all the criteria provided in S 60.752(b)(2) and be
  approved by the Administrator.
  1.1.9  Additional Information Specific to the Emission
  Guidelines
       Under the final EG, States are required to submit plans
  for existing sources and to provide for implementation and
  enforcement of emission standards for existing HSW landfills.
  The EPA has determined that these are health-based guidelines,
  meaning that state plans must be at least as stringent as the
  EG.  The final EG have been modified to reference the
  provisions of the NSPS for the specification of approved
  design plans for the gas collection and control system.
       The final emission guidelines stipulate that the existing
  MSW landfills emitting NMOC of 50 Mg/yr or greater when the
  State plan is approved must achieve compliance with the
  guidelines for collection and control systems within 3 years
  from the time of promulgation of the State regulations.  This
  time period allows 2.5 years for further site-specific testing
  (if elected by the owner or operator), preparation and review
  of a collection system design plan, and installation of the
  collection and control system; and 180 days for a performance
  test.
       In the case of  existing MSW landfills whose NMOC emission
  rates reach the emission rate cutoff of 50 Mg/yr sometime
  after the initial calculation, 3 years is  allowed to achieve
  compliance and conduct a performance test  from the date of the

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   first periodic  report documenting NMOC emissions of 50 Mg/yr
   or greater.
   1.1.10  Method  2E
       In Tier  3,  the  landfill owner or operator may determine
   the  landfill  gas flow rate with Method 2E by  installing a
   single cluster  of  three  extraction wells or five extraction
   wells equally spaced over the  landfill.  The  cluster wells are
   preferred, but  may be used only if the composition, age of the
   solid waste,  and the landfill  depth of the test area can be
           •
   determined.   The construction  of the extraction well is the
   same regardless of the pattern, and is specified in the
   method.
       Pressure probes are located along three  radial arms
   120  degrees apart  at distances of 3, 15, 30,  and 45 m from
   each extraction well.  The probes 15, 30, and 45 m  from each
   well are called deep probes and extend to a depth equal to the
   top  of the perforated section  of the extraction wells.  The
   three probes  located 3 m from  the well are called shallow
   probes and extend  to half the  depth of the deep probes.  The
   method has been revised  to require the pressure probes to be
   capped or the probe  hole to be refilled with  cover material
   after testing is complete.
       After the  wells have been installed and  the static flow
   rate of the landfill gas from  the wells has been measured,
   short-term testing is done on  each extraction well to
   determine:   (1)  the  maximum vacuum that can be applied by a
   blower to the wells  without infiltration of air into the
   landfill and  (2) the maximum radius of influence associated
   with the maximum blower  vacuum.
       A leak check  is required  to ensure accurate flow rate and
   safety, using Method 3C.  Maximum blower vacuum is determined
   by increasing the  vacuum and testing for infiltration of air
   into the landfill.  Method 2E  has been changed to specify the
   use  of a blower with a capacity of at least 8.5m3 per minute.
   Infiltration  of air  into the landfill is considered to have
   occurred if any of the following conditions are met:  the

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  temperature of the LF6 at the wellhead is more than 55 OQ or
  above the maximum temperature established during the static
  testing, the concentration of nitrogen in the LFG exceeds
  20 percent, or one of the shallow probes has a negative gauge
  pressure.  Once infiltration is indicated, the maximum blower
  vacuum is determined by reducing the blower vacuum at the
  wellhead until the nitrogen concentration is less*than
  20 percent, the gauge pressures of the shallow probes are
  positive, and the temperature of the landfill gas at the
  wellhead is less than 55 °C or below the maximum temperature
  established during the static testing.
       The temperature check is required to monitor for
  subsurface fires and aerobic conditions.  If infiltration does
  occur, oxygen is brought into the anaerobic environment
  beneath the cover.  Therefore, the temperature must be
  recorded during the static test.  This temperature is used to
  determine the maximum allowable temperature during the pumping
  test.  The pumping test temperature should not rise above
  55 °c or above the maximum temperature established during the
  static testing.
       The maximum radius of influence  (ROI) is the radial
  distance from the extraction well that is affected by the
  maximum blower vacuum.  This distance is determined by
  comparing the initial average pressure for each deep pressure
  probe distance for the static portion of the test with the
  final average pressures for each distance from the short term
  pumping portion of the test.  The farthest distance where the
  final average pressure is less than the initial average
  pressure is the maximum ROI.  The maximum ROI may be
  determined by plotting the pressure differentials  (initial
  pressure minus final pressure) versus the natural log of the
  distance from the wellhead.  Extrapolation is used to
  calculate  the distance at which the pressure differential is
  zero.  This distance is the maximum ROI.  Method  2E has also
  been revised to allow the use of a semi-log plot  of pressure


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   differentials versus distance from the  wellhead for
   determining ROI.
        Once the maximum blower vacuum and the maximum  radius  of
   influence have been established,  long-term testing begins.
   Long-term testing consists  of withdrawing  landfill gas  until
   two void volumes  have been  extracted.   A void volume is the
   amount  of landfill gas in a cylindrical volume defined  around
   the extraction well with a  radius equal to the maximum  radius
   of  influence.
        Duri'ng the long-term testing,  a stabilized flow rate is
   established and used to determine k,  the methane generation
   rate constant. This site-specific k is used  along with the
   site-specific landfill NMOC concentration  (determined using
   Method  25C or Method 18)  to recalculate the NMOC mass emission
   rate by using equations in  Method 2E.
   1.1.11     Method  3C
        Method 3C is used to determine the nitrogen concentration
   in  landfill gas samples by  injecting a  portion of the gas into
   a gas chromatograph (GC)  and determining the  nitrogen
   concentration by  a thermal  conductivity detector (TCD)  and
   integrator.   The  concentrations of methane, CC>2,  and oxygen
   can also be determined using this method.
        In Tier 2, when the NMOC concentration in the landfill
   gas is  determined by Method 25C,  Method 3C is used as a check
   on  the  integrity  of the sample.   Nitrogen  is  used as a
   surrogate for air,  and nitrogen concentrations of greater than
   20  percent in the sample indicate improper sampling  probe
   installation or sampling technique,  and the sample must be
   rej ected.
        In Tier 3, when Method 2E is used  to  determine  the flow
   rate of landfill  gas from the landfill, Method 3C is used to
   determine the presence of nitrogen concentrations exceeding
   20  percent in a landfill gas sample,  which is an indication of
   infiltration of air into the landfill.
        Method 3C is prescribed for  the option of monthly
   monitoring of nitrogen concentration for air  infiltration.

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  (Alternatively, the rule allows monthly monitoring of oxygen
  instead of nitrogen.)   Method 3C may also be used to leak
  check the above ground extraction well apparatus.  The
  landfill gas is extracted from the landfill by a blower and
  the flow rate is measured by a gas flow measurement device.
  Leaks in the well piping may affect the flow rate measured by
  the device significantly.  Therefore, Method 3C is used during
  Method 2E testing.  The concentration of N2 is measured at the
  wellhead sample port and at a point downstream of the flow
  rate measuring device, and a difference of greater than
  10,000 ppmv indicates a leak.  In this case, the owner or
  operator must locate and repair the leaks to the system and
  repeat the sampling and analysis.
  1.1.12  Method 25C
       Method 25C is used to determine the concentration of NMOC
  in landfill gas.  A sampling probe is perforated at one end
  and driven or augured to a depth of at least 1 m below the
  bottom of the landfill cover.  The sample probe depth
  requirement in Method 25C has been changed to read "extend no
  less than 1 m below the cover" to increase flexibility in
  sampling.  Additionally, a requirement has been added to both
  Methods 25C and 2E to cap or refill the probe holes with cover
  material once sampling or pressure testing has taken place.
  The owner or operator may choose to leave the probe in place
  and simply plug the sampling probe or remove the probe and
  refill the hole with cover material.
       Landfill gas is extracted from the probe with an
  evacuated cylinder at the rate of 500 ml/min
   (30.5 ±3.1 in3/min), and the carrier gas bypass valve is used
  to pressurize the cylinder with helium to approximately
  1,060 mm mercury absolute pressure.  The landfill gas will not
  condense when  it mixes with the dry gas.  This approach
  provides a method of addressing the small amounts of
  condensate without requiring a condensate trap, which would
  make the test more expensive and complicated.
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        The NMOC content of the sample  gas  is  determined  by
   injecting a portion of the gas  into  a  gas chromatographic
   column to separate the NMOC from carbon  monoxide  (CO),  CO2,
   and methane.   The NMOC are then oxidized to C02/  reduced to
   methane,  and measured by a flame ionization detector (FID).
   In this manner,  the variable response  of the FID  associated
                                                   •«
   with different types of organics is  eliminated.
        The method  for determining the  number  of samples  has
   changed from the proposal.   Instead  of using statistics based
            *
   on the scatter in the individual measured NMOC concentrations
   to determine the required number,  the  landfill must install  a
   minimum of two probes per hectare.   For  landfills greater  than
   25 hectares,  a minimum of 50 probes  are  required,  but  the
   owner or operator may use more  if desired.   Additional probes
   must be evenly distributed as well (i.e., 3 probes per
   hectare),  and all of the samples must  be used in  the analysis.
   1.2  SUMMARY OF  MAJOR COMMENTS  AND RESPONSES ON THE PROPOSED
        STANDARDS AND EMISSION GUIDELINES
        In the proposal Federal Register  notice,  the EPA
   requested comment on four issues,  (1)  the use of  an
   alternative format for the regulatory  cutoff,  (2)  the
   inclusion of materials separation requirements in the  NSPS and
   EG,  (3)  the establishment of a  separate  BDT for methane, and
   (4)  the inclusion of specific energy recovery requirements
   within the NSPS  and EG.  In addition to  discussing comments
   received on these topics, this  section summarizes comments on
   the selection and implementation of  BDT, and provides  the
   rationale for changes made to the regulations since proposal.
   1.2.1  Response  to EPA Solicitation  of Comments
        1.2.1.1  Alternative Regulatory Cutoff Format.  In the
   preamble to the  proposed regulations,  the EPA requested
   comment on its decision to use  the same  format for the removal
   of control equipment as was used for the installation  of the
   control equipment.  However, no comments pertaining to the
   alternative regulatory cutoff format were received.
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  Therefore, the format for equipment removal has not changed
  since proposal.
       1.2.1.2  Material Reparation Requirements.  Two
  commenters supported including material separation
  requirements within the proposed rules under Section 111 of
  the CAA, while seven favored leaving such requirements to be
  decided under RCRA.  After considering these comments, the EPA
  decided not to include materials separation requirements
  within the final rules because the EPA continues to believe
  RCRA and 'local regulations are the most appropriate vehicle to
  address wide-ranging issues associated with solid waste
  management for landfills.
       The final RCRA subtitle D preamble identified an array of
  initiatives designed to expand recycling efforts (56 FR 50980;
  October 9, 1991).  Under section II-D of that preamble, "EPA's
  Solid Waste Agenda for Action," the EPA explained the current
  strategy and stressed three national goals for MSW management.
  These goals were:  (1) to increase source reduction and
  recycling; (2) to increase disposal capacity and improve
  secondary materials markets; and (3) to improve the safety of
  solid waste management facilities.  The EPA strategy was
  composed of numerous initiatives, including market studies,
  federal recycling procurement guidelines, the development of
  training materials for State, local, and Tribal recycling
  coordinators, publications, and the establishment of a
  national recycling institute.
       More recently, the EPA is considering similar initiatives
  as part of its effort to encourage recycling through education
  and voluntary programs.
       1.2.1.3  ft Separate Best Demonstrated Technology for
  Methane.  Under the proposed regulations, MSW  landfill
  emissions, or LFG, was selected as the pollutant to be
  regulated.  Landfill gas is composed of various air pollutants
  including CC>2, methane, and NMOC.  Nonmethane  organic
  compounds were specified as a surrogate for MSW landfill
  emissions for measurement purposes.  The proposed regulations

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   required that air emissions  from  new and  existing MSW
   landfills emitting 150 Mg/yr of NMOC or more be reduced using
   a gas  collection and control system  as part of BOT.
       While some commenters to the proposed standards supported
   the use of NMOC as a surrogate for MSW landfill emissions,
   other  commenters considered  VOC,  total organic carbon  (TOC),
   and methane to be more appropriate surrogates.  Some of these
   commenters asserted that methane  deserved a separate standard
   of its own.   Other commenters concurred with the EPA's
            •
   proposal decision to consider only the ancillary benefits of
   methane when setting the standard based on NMOC emission
   potential.  These commenters asserted that additional
   consideration of methane was unwarranted, since significant
   methane reductions would occur indirectly from the  regulation
   of NMOC.
       Two commenters wanted a separate methane standard to be
   developed to more completely address the  health and
   environmental effects of methane, including the role of
   methane in global warming and the formation of ozone in the
   troposphere,  and the ability of methane to cause explosions
   and transport toxics.  Another commenter  stated that methane
   reductions should be considered directly  in the selection of
   BDT because of the serious health and welfare effects,
   including global climate change impacts,  of methane emissions.
       One commenter suggested that current and ongoing  methane
   studies be evaluated to  determine whether additional
   regulation of methane is warranted.   Another commenter said
   the regulation should place  more  emphasis on reducing  methane
   through such measures as source reduction and recycling,
   especially at small facilities.
       In setting standards and EG  which reflect BDT  under
   Section 111 of the CAA,  the  EPA considered reductions  of NMOC
   directly and methane reductions as an ancillary benefit.
   Methane reductions were  quantified and considered in selecting
   the stringency level of  the  rule.  However, NMOC was selected
   as a surrogate for MSW landfill emissions because NMOC

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  contains the landfill air pollutants posing more concern, due
  to their adverse health and welfare effects.  In addition, the
  EPA agrees with the commenters who considered separate methane
  controls as unnecessary because reducing NMOC concentrations
  in LFG will significantly reduce the amounts of methane
  emitted in LFG.  Specifically, the methane produced by
  existing landfills will be reduced by 39 percent due to the
  50 Mg/yr NMOC cutoff.
       The U.S. Climate Change Action Plan, released in
  October 1993, contains a series of actions to reduce emissions
  of methane from landfills and other sources.  The Climate
  Change Action Plan forms the cornerstone of the U.S. National
  Action Plan required by the Framework Convention on Climate
  Change, which the U.S. signed in 1992.  The EPA actions to
  reduce emissions of methane and other greenhouse gases will be
  guided by the directives contained in the Action Plan.
  Therefore, the EPA maintains that no separate BDT for methane
  is needed at this time.
       1.2.1.4  Energy Recovery Requirements.  Several
  commenters wanted energy recovery to be promoted through this
  NSPS.  Some recommendations for promoting energy recovery
  included: discussion in the preamble, relaxed regulations for
  sources implementing energy recovery, and economic incentives.
  Many commenters also supported the consideration of energy
  recovery in the cost-benefit analysis, and  some commenters
  indicated a site-specific feasibility analysis for energy
  recovery should be required by the regulation.  However,  only
  one commenter supported including provisions within these
  rules that would require the use of energy  recovery devices
  for some affected and designated sources.   One commenter
  suggested that energy recovery technologies also be defined  as
  BDT, and further suggested that the cost effectiveness
  analysis be revised  to incorporate the role of energy
  recovery.
       The EPA decided to incorporate energy  recovery in the
  nationwide impacts analysis by adding an energy recovery

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   scenario to the original flare analysis  upon which the
   selection of BDT is based.   As mentioned in section 1.3.2.1,  a
   conservative assumption was  made  addressing this  issue.   The
   analysis assumes that the 138  most  profitable  landfills  are
   the 138  landfills that operate annually  in the U.S.
   Therefore,  these top landfills were removed from  the analysis.
   Primarily due to this reason,  the energy recovery analysis did
   not predict any lower costs  than  did the original methodology
   in which all landfills are assumed  to use flares.
        The'revised nationwide  impacts analysis was  modified to
   select the least-cost of three control options for each  model
   landfill:   the use of flares,  I.e.  engines, or turbines  for
   the full control period.  In some cases,  use of an I.e.  engine
   or turbine results in a net  profit  because the energy recovery
   profits  outweigh the control costs.
        Additional cost data were gathered  for turbines and
   I.C.  engines for use in the  revised analysis.   The sources of
   data and costs derived from  them  are presented in "Changes to
   the Municipal Solid Haste Landfills Nationwide Impacts Program
   Since Proposal" (Docket No.  A-88-09,  Item No.  IV-M-3).  As
   discussed in section 1.3.2.1,  the EPA performed analysis which
   concluded that approximately 138  landfills would  recover
   energy annually in the absence of the regulation.
        After considering these comments and adding  an energy
   recovery scenario to the analysis,  the EPA continues to
   believe  that the use of energy recovery  should be a
   site-specific decision.   Such  a decision should be made  after
   the landfill owner or operator considers the potential for
   income from energy utilization given the uncertainty in  the
   amount of gas produced.   Many  other variables  come into  play
   when considering energy recovery, such as gas  market
   fluctuations,  gas production rates,  ability to market or
   distribute electricity produced,  and the quality  of the  gas.
   Not all  energy recovery ventures  from landfill gas have  been
   successful in the past.   Technical  difficulties vary from site
   to site  and may include such barriers as the gas  being unfit

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  for recovery because of non-combustible components or an
  insufficient flow rate to maintain dependable operation of
  equipment.  On the other hand, some landfills may generate
  adequate volumes of clean burning gas that would make energy
  recovery profitable.  For these reasons, the EPA is strongly
  encouraging, but not mandating, energy recovery within these
  standards.
       The EPA's Office of Research and Development has
  developed several technology transfer tools to help encourage
  energy recovery from landfills,  one tool is a software model
  and user's manual for estimating landfill air emissions using
  the equation and defaults specified in the rule.  The Landfill
  Air Emissions Estimation Model  (version 2.0) and user's manual
  can be obtained from NTIS or the EPA Control Technology Center
  at the phone numbers listed below.  The model also contains
  AP-42 emission factors for developing estimates for State
  inventories.
       Another aid to the regulatory work sponsored by the EPA
  is a report entitled, "Landfill Gas Energy Utilization:
  Technology Options and Case Studies," EPA-600/R-92-116, June
  1992.  This report includes detailed case studies of six sites
  for the range of every recovery option in use, data on over
  50 projects, and information on the capital and operating
  costs.
       The  EPA has also developed a report on the technical  and
  nontechnical factors to consider including a discussion of
  different philosophies of major operators of landfill gas
  recovery  projects regarding gas cleanup and operation.  The
  report is entitled "Landfill Gas Energy Utilization
  Experience:  Discussion of Technical and Nontechnical Issues,
  Solutions and Trends", EPA-600/R-95-035.  Two other reports
  developed by the EPA's Office  of Research and Development  in
  1995 are:   "Emerging Technologies for Landfill Gas
  Utilization" and "Methodologies for Quantifying Pollution
  Prevention  Benefits from Landfill Gas Control and
  Utilization".  These documents and the  ones discussed above

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   are  available  through  the National Technical  Information
   System at  (703)  487-4650  (phone) or  (703) 321-8547  (fax)  or
   the  EPA Control  Technology Center Hotline at  (919)  541-0800
   (phone)  or (919)  541-2157  (fax).  Technical assistance
   regarding  the  CAA regulation,  estimating landfill emissions,
   and  evaluating control and landfill  gas utilization options
   can  also be obtained by calling the  Control Technology  Center.
       The EPA has also  developed a Landfill Methane  Outreach
   Program to assist owners and operators interested in  landfill
   gas  energy recovery and to encourage more widespread
   utilization of landfill gas as an energy source.  Information
   regarding  the  Program  can be obtained by calling the  Landfill
   Methane Outreach Program Hotline at  (202) 233-9042.
   1.2.2   Rationale for Significant Chances to Regulation
       1.2.2.1  Selection of Design Capacity Exemption  Level.
   The  proposed rule included a design  capacity  exemption  to
   reduce the burden on small landfills.  Several  commenters
   discussed  the  proposed design  capacity exemption level  of
   100,000 Mg.  Several comments  were submitted  requesting an
   increase in the  exemption level.  An increase would relieve
   additional owners and  operators of small landfills  from the
   emission estimation and control requirements.   Two  commenters
   recommended a  specific higher  exemption level.  One of  the
   commenters contended that no additional MSW landfills having
   design capacities less than 100,000  Mg will be  built  and
   recommended an exemption  level of 1.0 million Mg.   The  second
   commenter  suggested an exemption level of 550,000 Mg, noting
   that landfills smaller than this would not emit more  than
   150  Mg/yr  NMOC,  and arguing that the lower exemption  level
   unnecessarily  increased the regulatory burden of the  standard.
   In addition, representatives of state and local governmental
   agencies who were consulted under Executive Order 12875
   recommended higher exemption levels  to relieve  small  entities
   of regulatory  burden.
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       One industry conunenter approved of the design capacity
  exemption of 100,000 Mg, but also noted that there would still
  remain considerable burden for small landfills that would be
  exempted at Tier 1.  However, the commenter, along with two
  other commenters, recommended that all MSW landfills be
  evaluated for NMOC emission rates, not only those above the
  design capacity exemption level.
         The design capacity cutoff of 100,000 Mg of waste was
  chosen at proposal so that no landfill would be exempted by
           •
  size and have actual emissions above the emission rate cutoff.
  In addition to the comments, changes to the data base and the
  emission modeling values prompted a reevaluation of the design
  capacity exemption level.
       The new design capacity exemption analysis evaluated a
  range of options from 500,000 Mg to 4.0 million Mg of waste.
  Two important considerations in the selection are the number
  of landfills exempted and the amount of potential NMOC
  emission reduction lost from the exempted landfills.
  The 2.5 million Mg exemption level would exempt 90 percent of
  the existing landfills while losing only 15 percent of the
  total NMOC emission reduction.  Therefore, 2.5 million Mg was
  chosen since losing 15 percent of the potential emission
  reduction is a reasonable tradeoff to relieve as many small
  businesses and municipalities as possible from the regulatory
  requirements, while still maintaining significant emission
  reduction.  The  lowest value considered, 500,000 Mg, only
  allows slightly more than 1 percent of the total emission
  reduction potential to go unregulated; however, only
  62 percent of the  landfills are exempted so the regulatory
  burden is higher than under the chosen option.  Exemption
  levels higher than 2.5 million Mg resulted  in less emission
  reduction.
       The 2.5 million Mg design capacity exemption level
  excludes those landfills, both public and private, who would
  be least able to afford the costs of landfill gas collection
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   and  control  systems.  Also, smaller  landfills are  less  likely
   to have  successful  energy  recovery projects.
        Since some  landfills  record waste by volume and have
   their design capacities  calculated in volume, the  EPA also
   established  an equivalent  design capacity exemption of
   2.5  million  cubic meters of waste.   The density of landfilled
   solid waste  varies  from  landfill to  landfill depending  on
   several  factors, including the  compaction practices.  Any
   landfill that reports waste by  volume and wishes to establish
   a mass design capacity must document the basis for their
   density  calculation.
        1.2.2.2 Selection  of the  Regulatory Stringency Level.
   Several  commenters  requested  a  more  stringent emission  rate
   cutoff,  while others favored  the 150 Mg/yr rate proposed, and
   some favored a less stringent standard.  One of the commenters
   asserted that the NMOC data provided by the EPA at proposal
   supports a more  stringent  level.  Other commenters stated that
   adding the benefits of energy recovery and abatement of global
   warming  to the economic  analysis would support a more
   stringent standard. Two commenters  supported a cutoff  level
   of 25 Mg/yr  because of the additional methane reductions that
   would result.  Another commenter favored a more stringent
   standard because the commenter  believed that health risks
   posed by landfills  between a  cutoff  of 25 Mg/yr and 150 Mg/yr
   may  be significant.
        One commenter  supported  an emission rate cutoff of
   250  megagrams per year.  This commenter stated that the BID
   and  regulatory impact analysis  (RIA) for the proposal did not
   provide  a clear  rationale  or  cost effectiveness for the
   selection of a 150  Mg/yr cutoff and  that actual health  and
   environmental benefits are uncertain.
        The Climate Change  Action  Plan, signed by the President
   in October,  1993, calls  for EPA to promulgate a "tough"
   landfill gas rule as soon  as  possible.  This initiative also
   supports a more  stringent  emission rate cutoff that will
   achieve  greater  emission reduction.

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       Due to the small-size exemption, only landfills with
  design capacities greater than 2.5 million Mg of waste or
  2.5 million cubic meters of waste will be affected by this
  rule.  It is estimated that a landfill of 2.5 million Mg
  design capacity corresponds to cities greater than 100,000
  people.  On the whole, large landfills service areas with
  large population.  A reasonable assumption is that many of
  these large landfills are in the 400 counties that have been
  designated as urban ozone nonattainment areas and are
  developing plans to address ozone nonattainment.
       Finally, the new data and modeling methodologies, which
  were published in the notice of data availability on June 21,
  1993, significantly reduced the estimated emission reduction
  and corresponding effectiveness of the rule.  Therefore, a
  more stringent emission rate cutoff would achieve similar
  emission reductions at similar cost effectiveness to the
  proposed rule.
       Based on all of these reasons, the EPA reevaluated the
  stringency level and chose an emission rate cutoff of 50 Mg/yr
  of NMOC for the final rules.  This revision would affect more
  landfills than the proposal value of 150 Mg/yr of NMOC;
  however, the 50 Mg/yr of NMOC will only affect less than
  5 percent of all landfills and is estimated to reduce NMOC
  emissions by approximately 53 percent and methane emissions by
  39 percent.  The 150 Mg/yr emission rate cutoff would have
  reduced NMOC emissions by 45 percent and methane emissions by
  24 percent.  The incremental cost effectiveness of control of
  going  from a 150 Mg/yr cutoff level to a 50 Mg/yr cutoff  level
  is $2,900/Mg NMOC reduction for new  landfills and $3,300/Mg
  for  existing landfills.
       The values  for NMOC cost effectiveness do not include any
  credit for the benefits for toxics,  odor, explosion control,
  or the indirect  benefit of methane control.  A revised  cost
  effectiveness could be calculated with an assumed credit  value
  for  one or more  of the other benefits.  As  an example,
  assuming a $20/Mg credit for the methane emission reduction,

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   the incremental  cost effectiveness  from the proposal  cutoff of
   150 Mg/yr  to the final  cutoff  of  50 Mg/yr would be  reduced to
   $l,300/Mg  NMOC.
        1.2.2.3  Gas Collection System Design Specifications.
   Many commenters  wanted  the proposed standards to allow more
   design flexibility,  some  wanted the EPA to encourage  States to
   allow alternative designs and  some  commenters requested  that
   the designs be required to be  site-specific.
        Some  commenters noted that the design specifications in
   chapter 9  of the proposal BID  were  too rigid, while one
   commenter  suggested  that  to foster  development of new designs,
   the design specifications in § 60.758 of the proposed NSPS be
   removed from the regulation and used only as guidance rather
   than as required design specifications.  Some commenters
   stated that the  collection and control design criteria were
   based on unproven and invalid  theories and models,  resulting
   in over designed systems.
        Other commenters recommended that the regulations
   designate  an alternative  collection system design based  on the
   South Coast Air  Quality Management  District  (SCAQMD)  rule,
   which uses integrated surface  sampling of total organic  carbon
   (TOC)  to determine if additional  gas control is needed.   One
   commenter  noted  that such surface sampling encourages system
   maintenance.
        The design  specifications proposed in § 60.758 were
   included in the  proposed  rule  to  provide a straightforward
   basis for  system design.  However,  because of the many site-
   specific factors involved in landfill design, alternative
   systems may be necessary. To  provide design flexibility, the
   final regulations no longer contain specific designs, but
   require all designs  to  be prepared  by a professional  engineer
   and submitted to the permitting authority for approval.   All
   designs must satisfy the  criteria for an effective  collection
   system provided  in S 60.759.   The removal of specific gas
   collection system design  plans from the rules will  encourage
   technological innovation  by allowing sources to design their

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  own gas collection systems to meet specific needs.  The
  enabling document will contain the specific design information
  removed from the regulation, so that if landfills wish to use
  the design specifications, they will be available.
       1.2.2.4  Operational Standards for Collection and Control
  Systems.  Several commenters identified a variety of
  operational considerations that may affect the installation
  and operation of collection and control systems, and they
  suggested that these considerations should be addressed by the
           •
  standards.  Some of these considerations related to the
  landfill environment, such as:  settlement or movement of
  landfill or cover surfaces; changing topography, weather, and
  barometric pressure; presence of on-site structures; gas
  generation rate; and existing passive venting systems.  Other
  considerations focused on management practices or operation of
  the collection and control system, such as:  equipment
  traffic; the effect of bailing waste; equipment leaks;
  maintenance and repair practices; treatment of leachate and/or
  condensate; provisions for flame-outs, downtime, malfunctions
  or pipe leaks; air injection; and the effects of sampling
  ports.
       The EPA agrees that these considerations will have an
  effect on the installation and operation of collection and
  control systems.  All of these considerations, however, vary
  from site to site, and the EPA judged that, in general, most
  of these concerns are best addressed by the local operator.
  The treatment of leachate and condensate is already addressed
  under RCRA  (subtitle D).
       The operational specifications provided in the proposal
  are not intended to replace the operator's knowledge of, and
  response to, the situations discussed above.  However, well-
  operated and we11-maintained equipment should be used to
  comply with these rules, which should keep air emissions
  through leaks in equipment  at a minimum.
       In addition to the removal of the prescriptive design
  criteria for gas collection systems, the EPA made several

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   logical  changes  to  the  proposed rules  on  issues raised by
   commenters.   Two of these  changes are  significant.  The  first
   change was to aggregate the various operational provisions
   that had been located at different points throughout  the
   proposed regulation in  a new  § 60.753,  "Operational standards
   for collection and  control systems."   Second,  as^suggested  in
   the proposal  preamble,  to  ensure that  the integrity of the
   landfill cover is adequately  maintained,  a  requirement to
   operate  the collection  system so that  surface  methane
   concentration is less than 500 ppm has also been  included.
       In  summary,  new §  60.753 addresses the following areas:
   (1) collection of gas from active areas containing solid waste
   older than 5  years,  and 2  years for areas closed  or at final
   grade;  (2) operation of the collection system  with negative
   pressure at each wellhead  (with exceptions  added  since
   proposal);  (3) operation of the collection  system with a
   landfill temperature less  than 55 °C  (or  a  higher established
   temperature)  and either a  nitrogen level  less  than or equal to
   20 percent or an oxygen level less than or  equal  to 5 percent;
   (4) operation of the collection system with a  surface methane
   concentration less  than 500 ppm;  (5) venting all  collected
   gases to a treatment or control device; and (6) operation of
   the treatment or control device at all times when the
   collected gas is routed to the control device.
       The requirement to collect gas from  areas containing
   solid waste was  changed from  2 years at proposal  for  all
   areas, to 5 years for active  areas and 2  years for closed or
   final grade areas.   A summary of comments on this requirement
   and rationale for the change  is contained in section  1.2.2.7
   on "System Expansion."
       The proposed requirement to maintain negative pressure at
   wellheads was not changed. The EPA has,  however, provided  for
   three exceptions when it may  not be possible for  sources to
   maintain negative pressure at wellheads.  These exceptions  are
   also discussed in section  1.2.2.7.
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       The proposed requirement for operation of the collection
  system with nitrogen levels less than or equal to 1 percent
  was revised to 20 percent based on new information received
  since proposal.  An alternative provision for maintaining an
  oxygen level less than or equal to 5 percent, and an
  additional provision maintaining a temperature of less than
  55 °C (or a higher established temperature) were added.  The
  rationale for these changes is provided in section 1.2.2.6 on
  "Monitoring of Operations."
       A significant new requirement to operate the gas
  collection system with a surface methane concentration less
  than 500 ppm (along with monitoring provisions to ensure
  maintenance of this concentration) was added after proposal.
  This surface emission limit was included under the operational
  standards, because the EPA is using it to verify that the
  system is adequately operated and maintained and not to ensure
  an emission limit, surface or otherwise, as normally
  constructed under Section 111.  The rationale for this
  requirement is also provided in section 1.2.2.6.
       The requirements to vent all emissions to a treatment or
  control device and to operate the device at all times when the
  emissions are being routed to the device have not changed
  since proposal.  Provisions for downtime and malfunction are
  described in section 1.2.2.5.
       In conjunction with the new operational provisions, the
  compliance, testing, and monitoring sections were revised to
  reference and support these new or relocated provisions.
       1.2.2.5  Start—up. Shutdown, and Malfunction Provisions.
  In response to the comments regarding system start-up,
  shutdown, and malfunction, the EPA has added provisions in
  S 60.755 of the  final NSPS as follows:

       "(e)  The provisions of this subpart  apply at all
       times, except during periods of start-up, shutdown,
       or malfunction, provided that the duration of
       start-up, shutdown, or malfunction shall not exceed
       5 days for  collection systems, and 1  hour for
       treatment or control devices."
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        When considering  the  various provisions  for  start-up,
   shutdown or  malfunction  conditions recommended by the
   commenters,  the  EPA has  chosen to include provisions that are
   linked to compliance for ease of implementation.
        The 5-day exemption period for collection systems was
   selected in  recognition  that a major problem  with*a collection
   system will  likely take  some time to locate and solve but also
   that the landfill  is not going to stop generating LFG.   In  the
   design and operational standards of these rules,  compliance
   with the standards is  meeting the requirements for the
   installation and operation of a properly-designed system.   The
   EPA  recognizes that a  shut down system cannot possibly meet a
   standard requiring that  a  collection system be actively
   collecting LFG.  In recognition that flame-outs and problems
   with the collection system do occur, the EPA  did  not want to
   render owners and  operators of well-designed  and  operated
   systems out  of compliance  with the standards  under normal
   operating circumstances.   Therefore, a reasonable exception to
   the  compliance provisions  was sought.
        The EPA has decided to include a 1-hour  repair window  for
   control devices  within the final NSPS and EG.  The 1-hour
   period was selected for  control devices because,  in practice,
   most sites currently collecting landfill gas  have multiple
   control devices, whether multiple flares, boilers, I.e.
   engines,  turbines, fuel  cells, or combinations of the above.
   Therefore, only  a  short  period of time would  be necessary to
   relight a flare  or reroute the collected gas  to an alternative
   device.
        While all periods when collection or control equipment
   are  not operating  must be  recorded, only periods  in excess  of
   5  days for collection  systems and 1 hour for  control devices
   must be reported in the  annual excess emission report.   And,
   as required  in § 60.11(d), the collection and control system
   must be maintained and operated at all times, including
   periods of start-up, shutdown or malfunction, in  a manner

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  consistent with good air pollution control practice for
  minimizing emissions.
       Localized problems with crushed pipes, etc., may be
  resolved through adjustments to the draw from other wells in
  the vicinity until repair is effected.  If the blowers need to
  be repaired or replaced, the collection/control system may be
  able to function temporarily as a passive system while repairs
  are effected.  However, the EPA has no data upon which to base
  how long .such an arrangement would be feasible.  Therefore,
  owners and operators should take care to plan for such
  contingencies.  Whether the owner or operator has arranged
  with vendors for quick turnaround on replacement parts, has
  spare system components on site, or has multiple devices on
  line so that the flow may be distributed among them,
  compliance can be maintained in a number of ways.  Therefore,
  the EPA has elected to specify a downtime that is acceptable
  under these rules, and leave the actual repair strategy to the
  owners and operators.
       1.2.2.6   Monitoring of Operations.
       Control Device Monitoring—Two commenters questioned how
  the residence time during the initial performance test of a
  flare could be monitored and suggested perhaps the
  requirements intended to require calculation of the residence
  time.  One of the commenters also suggested a monitoring
  schedule be added.
       The monitoring provisions of the MSW  landfill NSPS are
  based on typical Section 111 provisions for open flares and
  enclosed combustion devices.  New provisions allow sources to
  monitor the use of bypass systems using car seal or lock and
  key type configurations instead of monitoring  flow to the
  control device.  These provisions were added to reduce the
  burden imposed by monitoring requirements.
       The intent of this section of the regulation is to
  require that residence time be determined  during the initial
  performance test for enclosed combustors.  Flares are open
  combustors which have no "residence time"  associated with the

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   combustion.   The  final  regulation was changed to reflect that
   residence  time should be  determined  in conjunction with gas
   flow measurements rather  than  "monitored."  After the  initial
   performance  test,  the NSPS  only requires that temperature and
   flow (or bypass)  be  recorded with equipment calibrated,
   maintained,  and operated  according to the manufacturer's
   specification.
        Two commenters  recommended that the flare  flame,  rather
   than the pilot flame, be  monitored to verify that the  flare  is
   operating  at all  times.   The monitoring provisions have been
   changed to allow  monitoring of either the pilot flame  or the
   flare flame  itself to determine if the flare is operating.
   Pilot flare  monitoring  is allowed because the temperature of
   the  flare  flame is high and may cause the thermocouple to burn
   out  more quickly.  The  requirement to monitor flow to  the
   flare or other control  device  every  15 minutes, or to  prevent
   bypass of  the control device using a car seal or lock  and key
   type system,  is to ensure that the collected landfill  gas is
   being conveyed to a  flare or other suitable control  device
   rather than  being discharged to the  atmosphere.
        Surface Monitoring—Some  commenters recommended that the
   regulations  incorporate an  alternative collection system
   design provision,  which would  establish a performance  standard
   based on the SCAQMD  rule.   The SCAQMD rule uses integrated
   surface sampling  of  TOC to  determine the need for additional
   gas  control.   This would  allow more  flexibility for  the gas
   collection designs.  One  commenter noted that their  State
   regulation requires  that  gas collection systems be designed  so
   that surface concentrations of methane do not occur  above
   certain levels.   The commenter asserted that a  surface test
   encourages system maintenance.  Commenters also asserted that
   a surface  emission standard which landfill operators must
   maintain would allow maximum design  flexibility and
   encouraging  more  cost effective innovations.
        One commenter was  concerned about the integrity of the
   landfill cover and that cracks in the cover could allow

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  emissions to the atmosphere even when an effective collection
  system has been installed.  As mentioned in the proposal
  preamble, surface emission monitoring as used in the SCAQMD
  seems appropriate for determining that closer well spacing is
  in fact needed.  As mentioned in the proposal preamble, the
  EPA was already considering what role the California test
  might reasonably fill in these regulations (see
  56 FR 24492-24493).
       The EPA considers surface emission monitoring to be an
  appropriate tool for monitoring both cover integrity and the
  effectiveness of well spacing.  Therefore, some aspects of the
  surface emission monitoring test have been incorporated in the
  new S 60.753, where all of the operational provisions for the
  collection system have been brought together.
       After initial installation of the collection system,
  owners and operators will be required to operate the
  collection system with a methane concentration less than
  500 ppm at all points around the perimeter of the collection
  area and along a serpentine pattern across the entire surface
  of the landfill.  Compliance with this operational standard is
  to be demonstrated by monitoring surface concentrations on a
  quarterly basis using an organic vapor analyzer, flame
  ionization detector, or other portable hydrocarbon monitor.
  If an instrument reading of 500 ppm or greater is produced,
  the location of the exceedance must be recorded, and cover
  maintenance or adjustment to the vacuum at adjacent wellheads
  must be made within 10 calendar days.  The 10-day schedule was
  selected to allow the personnel to continue monitoring without
  stopping to make adjustments, but to assure that conditions at
  the locale of the exceedance are attended to quickly.
       A second measurement must be taken within 10 days.   If a
  second exceedance is recorded at the same location, additional
  adjustments shall be attempted and additional monitoring
  performed within  10 days.  If a third exceedance is recorded
  at that  location, an additional well must be installed within
  120 days of the first exceedance.

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        The methane  concentration  level  of  500 ppm was chosen
   based on data  received  from  numerous  sources,  including:
   (1)  information provided  by  the SCAQMD stating that this was
   an appropriate level  and  the level used  at landfills  in that
   district;  (2)  information indicating  that some leak detection
   programs for other industries currently  use 500 pj?m and
   analyzers  are  capable of  detecting this  level;
   (3)  instrumentation specifications citing this as  an
   appropriate number and  that  familiarity  with this  level is
   broad;  and (4)  site visits conducted  by  the EPA indicating
   that 500 ppm is an acceptable detection  level.
        Surface monitoring will provide  a safeguard against
   uncertainties  in  well density determination, no matter  what
   collection method is  used.   The new surface monitoring
   provisions include requirements for increased  monitoring and
   corrective actions upon exceedance of 500 ppm.
        Nitrogen  Monitoring—Many  commenters stated that the
   1  percent  nitrogen limit  in  the proposed standard  for
   infiltration detection  was unrealistic and reported typical
   levels of  5 to 11 percent.   Some commenters stated that
   nitrogen measurements are expensive and  that other methods,
   such as well temperature  or  percent methane should be allowed
   as indicators  of  excess air  infiltration.
        In Method 2E as  well as daily operation,  the  nitrogen
   concentration  in  the  extracted  LFG is important because it
   indicates  if the  maximum  vacuum achievable without air
   infiltration is being obtained  from the  landfill.  The  EPA  set
   the  nitrogen limit as a safety  measure to avoid fires and
   explosions that may result from pulling  too much air  into the
   landfill and to avoid altering  the anaerobic state of the
   landfill.   For compliance purposes, the  main concern  is that
   the  system is  pulling at  maximum capacity up to the point of
   infiltration.
        The monitoring provisions  of the final NSPS have been
   revised after  consideration  of  the comments.   The  nitrogen
   limit during operation  of the collection system at the

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  wellhead has been increased to 20 percent based on the
  evaluation of numerous comments on this subject.
       The nitrogen limit in Methods 2E and 25C has also been
  increased to 20 percent.  In Method 2E, a sample found to
  contain more than 20 percent nitrogen indicates infiltration.
  If a sample is found to contain more than 20 percent nitrogen
  in Method 25C, then that sample should be removed from the
  collection.  The equation for calculating the NMOC
  concentration in Method 25C has also been revised to correct
  the NMOC concentration in the LFG sample to zero percent
  nitrogen.
       Because commenters indicated that nitrogen measurement
  via Method 3C is impractical, provisions have also been added
  that allow for the monitoring of oxygen using Method 3A.  The
  measurement of oxygen via portable monitoring devices is
  already being done in the field, and an oxygen threshold of
  5 percent would correlate to an nitrogen value of 20 percent.
       Temperature Monitoring—A provision requiring the
  temperature to be maintained below a set limit has also been
  added.  This temperature limit is 55 °C, or a higher
  temperature at each well that the owner or operator can
  document will not cause fires or inhibit anaerobic
  decomposition.  If the LFG temperature at the wellhead
  increases above the temperature threshold, the new provisions
  require an adjustment of the vacuum to reduce the temperature.
  The value of 55 °C was cited by industry experts as an alert
  temperature that may indicate a problem.  Since temperature
  variability exists between landfills and between wells within
  a landfill, the provision to establish higher operating
  temperatures at individual wells has been added.  A higher
  temperature limit will be allowed, however, only if the owner
  or operator can demonstrate with supporting data that the
  higher temperature does not cause fires or adversely affect
  the anaerobic decomposition of the waste.
       As with nitrogen monitoring, an alternative method for
  measuring temperature may be used if it is documented and

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  maintained with  the  landfill records.  The EPA realizes many
  owner  or  operators presently extracting gas use other
  compounds, conditions,  and  theoretical ratios to monitor  for
  air  infiltration.  Therefore, this  flexibility allows them to
  use  these methods for demonstrating compliance with the
  regulation.
       1.2.2.7   System Expansion.  Commenters expressed two
  primary concerns dealing with system expansion.  The first
  concern centered around the requirement to expand  extraction
  systems into  each area  after 2 years of waste deposition.
  Some commenters  suggested that such a timeframe is
  unreasonable  and does not coincide  with common operation
  practices.  Commenters  suggested that other means, such as
  emission  potential,  be  used to determine when wells should be
  placed rather than a time requirement or site-specific data.
  The  second concern was  the  requirement to install  an
  additional well  in the  vicinity of  a well where negative
  pressure  cannot  be achieved through valve adjustment at the
  wellhead.  Commenters indicated the provisions were vague and
  that a time schedule should be added to the provisions.
       The  EPA  has reanalyzed the provisions of these rules in
  response  to public comment  regarding both maintenance of
  negative  pressure at the wellhead and the addition or
  replacement of wells.   These changes to the rule were placed
  in § 60.753,  "Operational Standards for Collection and Control
  Systems," and S 60.755, "Compliance Provisions."
       The  provision requiring maintenance of negative pressure
  at wellheads  has not been changed.   However, exceptions to
  negative  pressure at wellheads have been added to  the rules.
  The  exceptions are as follows:   (1)  If there is a  significant
  increase  in temperature (or fire),  in which case the source
  may  need  to reduce the  vacuum or go to positive pressure. If
  this occurs,  the owner  or operator  must record and report the
  event; (2) If the source is using a synthetic cover or
  geomembrane.   In this case  the owner or operator must
  establish the maximum positive pressure allowable  in the

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  design plan and have it approved.  If this is not in the
  original design plan, the plan must be updated to include
  positive pressure limits; and (3) In an area of declining gas
  flow, wells that are shut off to allow higher flows at
  adjacent wells may experience static positive pressure.  The
  owner or operator must update the design plan and^have it
  approved before shutting off wells in declining areas.
       After initial installation of the collection system,
  owners and operators will be expanding the collection system
  over time to provide adequate coverage for all active areas in
  which waste has been deposited for 5 years.  The 5 year period
  is believed to be more re -sonable and consistent with common
  landfill practices than the proposed 2-year period for active
  areas of the landfill.  A given area is typically active for
  more than 2 years.  If collection system wells are required to
  be installed within 2 years, they will likely get covered
  over, decreasing their operational life.  This scenario would
  increase costs and be inefficient.  Thus, a 5-year period is
  allowed.  A period longer than 5 years is not allowed because
  emissions from a given block of waste will decline over time,
  so it is important to install collection and control systems
  as soon as reasonably practical.  For areas that are closed or
  at final grade, collection system wells must be installed
  within 2 years.
       There are also two cases in which wells must be added
  unexpectedly—when negative pressure cannot be achieved at a
  given wellhead within a 15 days  (except as noted in the three
  exceptions above) and when surface methane levels cannot be
  reduced below 500 ppm after three attempts in 30 days.
       In the first case, 15 days  are allowed to restore
  negative pressure at the wellhead and thereby avoid
  installation of an additional well.  The principal reason
  positive pressure is likely to occur is that the collection
  system capacity in the  locale of the well  is less than the
  production in the area.   Either  collection capacity can be
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   increased through adjustments  to  the  vacuum,  or  system
   expansion is warranted.
        The 15  days allows  time for  a  surge  in generation after
   significant  rainfall  to  subside or  for the operator to make
   all attempts to restore  negative  pressure through  other means.
   Any operational adjustments  the operator  can  make  to  restore
   the well to  proper function  within  this timeframe* are not
   precluded by these rules.  If  negative pressure  cannot be
   restored within this  15-day  period, however,  the area is
   producing more gas than  the  wells in  that area are able to
   handle,  and  the installation of an  additional well is
   warranted.   If rainfall  results in  increased  generation on a
   regular  basis,  an additional well is  also warranted to
   accommodate  this regular increase in  gas  production.
        In  the  case when methane  concentrations  are monitored at
   500 ppm  or more,  two  10-day  periods are allowed  after initial
   measurement  to reduce surface  methane concentrations  below
   500 ppm.   There are two  reasons likely to contribute  to
   excessive methane levels—cover failure or insufficient
   density  of wells.   When  excessive methane concentrations  are
   recorded,  10 days are allowed  for personnel to evaluate the
   problem.   If the cover has been disturbed, maintenance will
   likely reduce surface levels.  On the other hand,  if  the
   density  is insufficient  for  the gas production level  in the
   vicinity,  adjustment  of  the  vacuum  may extend the  effective
   area and methane concentrations also  decrease.   An increase  in
   vacuum cannot always  be  used,  however, because there  is a
   trade-off in increasing  the  vacuum  and avoiding  excessive air
   infiltration.   Therefore,  if the  vacuum is increased  as much
   as  possible  without excessive  infiltration and the surface
   methane  concentrations still reach  or exceed  500 ppm,
   installation of an additional  well  is warranted.
        Because disturbance of  the cover can coincide with an
   ineffective  area of influence, the  EPA has allowed an
   additional 10 days after a subsequent exceedance.  It is
   expected that methane concentrations  will usually  subside

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  after cover maintenance or vacuum adjustments are made.  The
  EPA believes, however, it would be possible for landfill
  personnel to locate and repair cracks or other flaws in the
  landfill cover, thinking that the repairs would address
  excessive methane levels that result, at least in part, from
  an ineffective area of influence.  However, if the area is
  highly productive, excessive methane concentrations might
  still be monitored in the subsequent 10-day period in spite of
  the repairs to the cover.  In this case, an adjustment to the
  vacuum at* adjacent wells may still restore surface methane
  concentrations to acceptable levels, even though a second
  exceedance was recorded.  Rather than requiring that owners
  and operators remonitor at the location of every exceedance,
  the EPA elected to require remonitoring only when the initial
  attempt to reduce surface concentrations has been
  unsuccessful.  Therefore, varying durations are allowed to
  attempt to reduce surface methane concentration to below
  500 ppm before the installation of an additional well would be
  required.
       In both cases of unscheduled system expansion, 120 days
  after initial exceedance are allowed for the installation of
  the required well.  The 60 days beyond that allowed for
  scheduled expansion is reasonable because the availability of
  materials, drilling rigs or contract personnel for an
  unscheduled  installation, although anticipated in a general
  sense, make the installation of these wells in the 60  day time
  period less  feasible.
       1.2.2.8   Revision of Tier Defaults.  Several commenters
  challenged the default values for NMOC concentration,  C^oo
  methane generation rate constant, k, and methane generation
  potential, Lo.  Most  of the commenters argued that the values
  used were overly  conservative and that  inadequate technical
  justification was provided for the values  used.
       The EPA believes some of the commenters may have  been
  confused by  the nationwide impacts modeling.  The values
  chosen for the tier defaults were not used to model nationwide

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   emissions.   A more sophisticated analysis  was used in the
   modeling to select the standard involving  ranges  of values.
   The tier default values were chosen after  the nationwide
   modeling was complete.
        As explained in the preamble to the proposal,  the
   selection of the default values provided in  the tier
                                                    •»
   calculation was not based on test data alone (56  FR 24489;
   May 30, 1991).  Rather, the default values were selected after
   development of the nationwide impacts analysis to obtain a
   balance between lost emission reduction potential and cost  of
   performing the field tests in Tiers 2 and  3  on a  nationwide
   basis,  as described in the memorandum entitled "Documentation
   of Small Size Exemption Cutoff Level and Tier 1 Default Values
   (Revised)" (Docket No.  A-88-09,  Item No. IV-B-6).  Lost
   emission reduction potential is the loss of  emission reduction
   due to  exempting landfills through the tier  calculations when
   the landfills are actually greater than the  emission rate
   cutoff.  The values for k, Lo,  and C^QC are within an
   accepted range and were selected to minimize those landfills
   that actually emit more than 50 Mg/yr of NMOC but could
   calculate emissions below the cutoff using the defaults. The
   three defaults comprise a combination that best achieved the
   balance between lost emission reductions and the  cost of site-
   specific testing to replace the default CJJHOC and * values  in
   the tier system.
        The new default values of 0.05/year for k, 170 m3/Mg for
   Lo,  and 4,000 ppmv for CJJMOC are for use *n  tne Tier analysis.
   The memorandum "Methodology for Revising the Model Inputs in
   the Municipal Solid Waste Landfills Input  Data Bases
   (Revised)" (Docket No.  A-88-09,  Item No. IV-M-4)  discusses  the
   approach used to reevaluate and select these default values.
        1.2.2.9  Revision of Method 25C
        Method 25C—A few commenters stated that Method 25C needs
   to take the gas condensate into account.   Method  25C was
   revised to include evacuation before and pressurization
   afterwards with helium.  The landfill gas  will not condense

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  when it mixes with the dry gas.  This approach provides a
  method of addressing the small amounts of condensate without
  requiring a condensate trap, which would make the test more
  expensive and complicated.
       Implementation of Method 25C—Tier 2 requires performing
  Method 25C at a number of surface locations to determine a
  site-specific landfill gas concentration.  Many commenters
  stated that the statistical approach to calculate the number
  of samples and the confidence level is not supportable.
  Others stated that thorough sampling across the whole surface
  would give a better average due to the extreme variability in
  waste composition.
       In an effort to simplify the Tier 2 process and address
  many of the comments, the number and location of Method 25C
  sampling probes were revised.  Each landfill will take two
  samples per hectare of surface area up to 50 samples.
  Therefore, any landfill greater than 25 hectares may take a
  minimum of 50 samples.  Since the confidence level calculation
  was abandoned, only one time period is needed for
  recalculation of the gas concentration.  An active landfill
  that calculates the annual emission rate to be below 50 Mg
  NMOC/yr in Tier 2 will need to retest the gas concentration
  every 5 years.
  1.3  SUMMARY OF IMPACTS OF PROMULGATED ACTION AND ALTERNATIVES
       Environmental, energy, and economic impacts of NSPS or EG
  are normally expressed as incremental differences between
  facilities complying with the  final standards or guidelines
  and those same facilities if no NSPS or guidelines were in
  effect.  At present, very few  State or Tribal agencies have
  landfill regulations that address complete landfill gas
  control, and few new or existing landfills would be affected
  by these State, local, or Tribal regulations.
       For most NSPS and EG,  emission reductions and costs are
  expressed in annual terms.  In the case of the NSPS and
  guidelines for landfills, the  final regulations require
  controls at a given  landfill only after the  increasing NMOC

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   emission rate reaches  the level  of  the  regulatory  cutoff.   The
   controls are applied when the  emissions exceed the threshold,
   and they must remain in place  until the emissions  drop  below
   the cutoff.   However,  this process  could take as long as  50 to
   100 years for some landfills.  During the control  period,
   costs  and emission reductions  will  vary from year  to  year.
   Therefore, the annualized numbers for any impact will change
   from year to year.
       Because of the variability  of  emission  reductions  and
   costs  of the final standards and guidelines  over time,  the  EPA
   judged that  the net present value  (NPV)  of an impact  is a more
   valuable tool in the decision  process for landfills and has
   used NPV in  the development of both the proposal and  final
   nationwide impacts.  The NPV is  computed by  discounting the
   capital and  operating  costs and  emission reductions that  will
   be incurred  throughout the control  periods to arrive  at a
   measure of their current value.  In this way,  the  NPV accounts
   for the unique emission patterns of landfills when evaluating
   nationwide costs and benefits  over  different discrete time
   periods for  individual sources.  Thus,  the impacts presented
   include both fifth year annualized  estimates and estimates
   expressed in terms of  NPV in 1992.
   1.3.1   Revisions to the Data Base
       During  the period between proposal and  promulgation, all
   the data bases of landfills and  modeling values used  to
   estimate emissions were reevaluated in  response to public
   comments.  After review of the data bases, the following
   aspects of the modeling were revised as discussed  below:   (l)
   scale  factors; (2)  NMOC concentrations; and  (3) methane
   generation rate constant (k) and methane generation potential
   (L0) pairs.
       The Office of Solid Waste (OSW) data base used at
   proposal included 931  landfills  that were identified  as either
   small  or large landfills by a  scale factor assignment.  The
   OSW defined  small landfills as those landfills accepting  less
   than 500 tons/day of waste, while large landfills  are those

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  landfills accepting 500 tons/day or more of waste.  A scale
  factor was applied to each landfill in the data base, which
  resulted in a scaled-up total number of landfills to reflect
  the true population.  The scale factor assignments were later
  reviewed to ensure consistency with the OSW criteria for small
  and large landfills.  Based on the OSW tons/day criteria, some
  scale factor assignments were then revised and the primary
  scale factors for large and small landfills were adjusted to
  yield the corrected number and proportion of small and large
  landfills.  These adjustments result in a lower annual waste
  acceptance rate than the proposal level.  This in turn results
  in a somewhat lower NMOC baseline emission rate.  Compared to
  the nationwide impacts analysis at proposal, fewer landfills
  would be expected to emit above any given stringency level as
  a result of this change in scale factor.
       The values for CHMQC used for the proposal, which are
  used as an input parameter in the model, were also reviewed
  and revised in response to public comment.  The new data base
  values result in a lower average NMOC concentration than was
  reflected in the proposal nationwide impacts analysis.
       The values for k and Lo were also reviewed and
  regenerated.  The result of the recalculation of k, Lo pairs
  was a lower estimated overall landfill gas flow rate on a
  nationwide basis.
       The reanalysis consisted of a closer look at each value
  previously included in the nationwide impacts analysis as well
  as the inclusion of additional values obtained from ongoing
  studies.  The notice of data availability placed  in the
  Federal Register  (58 FR 33790; June 21, 1993) outlined the new
  data and reanalysis occurring between proposal and
  promulgation.
       In the reanalysis, for data to be used to obtain k
  values, the following had to be available:  test  year, year
  landfill opened, year  landfill closed  (if closed), amount of
  solid waste "in-place" in the test year, solid waste
  acceptance rate, and the actual methane flow rate.   For data

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   to be used to obtain NMOC concentrations,  the  following had to
   be available:  the total  NMOC concentration and associated
   units (e.g.,  ppmv as hexane,  ppmv as  methane),  the methane and
   C(>2 concentration (to correct for air infiltration since
   landfill gas  is primarily methane and CO2)/  and the test
   method used.   Also,  the test  method had  to be  comparable to
   the EPA Method 25C.
        As a result of these revisions to flow rate and
   concentration,  both the MSW landfill  emissions and NMOC
   emissions are less than earlier estimates.   Therefore,  the
   NMOC and methane baseline emissions are  lower,  and it is
   estimated that control would  be required at fewer landfills at
   any given stringency level, in comparison with the proposal.
   1.3.2  Revisions to the Modeling Methodology
        Considering public comment,  the  EPA revised the methods
   for assessing nationwide  impacts. Some  landfills presently
   choose to employ energy recovery systems independent of any
   regulatory requirements because energy recovery is a
   profitable operation.   These  profitable  landfills are removed
   from the cost analysis because the cost  analysis evaluates the
   potential impact of regulatory requirements on landfills that
   have not yet  chosen to install recovery  systems.  The EPA also
   added a least cost modeling scenario  to  supplement the
   proposal costing methodology.  The least cost  scenario
   estimates impacts if all  landfills used  energy recovery
   whenever the  situation was economically  more attractive than
   simply flaring the gas.
        1.3.2.1   Profitable  Landfills.   As  reflected in the
   proposal BID  and preamble, and stated by some  commenters,
   there are market impediments  that discourage landfill systems
   developers from taking a  risk on energy  recovery systems even
   though the standard would provide additional incentive to
   install energy recovery systems by requiring landfill gas to
   be controlled.   In contrast,  there is also some incentive to
   install energy recovery devices to reduce dependence on fossil
   fuels.   The EPA has determined that some landfills that could

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  achieve a profit by installing an energy recovery device would
  do so even in the absence of a regulation.  In cases where
  landfills would combust the gas in the absence of the
  regulation, the estimate of nationwide impacts of the
  regulation should not include the emission reductions and the
  negative control costs for these landfills because
                                                  • v
  installation of controls is not a result of the regulation.
  Not all landfills that could make a profit from energy
  recovery, however, would install energy recovery devices
           •
  unless required to apply control by the regulation.  As
  discussed below, the impacts of the final rule have been
  calculated to exclude credit for those landfills that would
  control in the absence of the rule.
       The EPA prepared a study (Docket No. A-88-09, Item
  No. IV-M-2) that concluded that, on average, for each year
  between 1992 and 2002, 138 landfills would be expected to use
  energy recovery, whether or not a regulation was in place.
  These landfills would most likely use energy recovery in
  absence of the NSPS and EG and would be the landfills that
  would make the most profit by using energy recovery.
  Therefore, the EPA decided to remove the  138 most profitable
  landfills from the data base used to calculate nationwide
  impacts for existing sources.
       The costs and profits of energy recovery at a given
  landfill vary depending on when the controls are installed and
  removed.  This time period varies depending on the stringency
  of the regulatory alternative because it  will take a longer
  period of time for the emissions at a given landfill to drop
  below a more stringent cutoff level.  Using the nationwide
  impacts program from the proposal, the control period of each
  landfill was varied and total costs were  determined for each
  period.  The control period was varied for each landfill by
  running the nationwide impacts program at various  stringency
  levels which corresponded to different control periods  (from a
  minimum control period of 15 years to a maximum that varied
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  with each  landfill).  A  list was generated that contained all
  the landfills that  were  profitable for any control period.
       Once  the list  of profitable landfills was generated, the
  most profitable ones were  identified and then deleted  from the
  landfill data base  until a number representing 138 after
  scaling were removed.  Since these landfills represent
  voluntary  control in the absence of the standard, their
  emission reductions do not result from the NSPS and EG.
  Therefore,  they were removed entirely from the analysis
   (including the baseline).  Since the most profitable
  landfills,  rather than the ones that would actually control  in
  the absence of the  regulation, were removed, the analysis
  assumes the maximum lost emission reduction and corresponding
  lost profit.  In reality,  not all of the most profitable
  landfills  are recovering due to other barriers.
       For the NSPS,  a comparable number of landfills were
  removed from the data base of new sources since this data base
  effectively replaces the data base of existing sources over
  time.
       1.3.2.2  Least Cost Modeling.  A least cost scenario was
  added  to the nationwide  impacts program to reflect the use of
  energy recovery devices  in cases where these cost less than
  flares.  In the least cost scenario portion of the program,
  the least  cost of the flare, turbine, or internal combustion
   (I.e.) engine options was  chosen for each landfill.  The  least
  cost decision was made by  comparing the costs of using each
  control device throughout  the entire control period.   The
  costs  for  I.e. engines and turbines included revenue from the
  sale of the electricity  generated.  The modeling program then
  chose  the  option that had  the least net cost.  The results of
  the least-cost control option at each landfill are included  in
  the final  nationwide impacts analysis.
       Due to the deletion of the most profitable  landfills and
  the selection of conservative discount rates in the analysis,
  the least  cost option did  not provide lower cost numbers.  The
  total  cost estimates for the two methods were very similar.

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  Therefore, the chosen options were based on the flare-only
  analysis as was done at proposal.
  1.3.3  Alternatives to Promulgated Action
       The regulatory alternatives are discussed in the preamble
  for the proposed standards and guidelines (56 FR 24468;
  May 30, 1991) and in chapter 5 of the proposal BID
  (EPA-450/3-90-011a).  These regulatory alternatives reflect
  the different levels of emission control.  The regulatory
  alternative selected was based on the BDT, considering costs,
  nonair quality health, and environmental and economic impacts
  for MSW landfills.
       The impacts of the proposed regulatory alternatives and
  additional alternatives were reevaluated based on the new data
  described in the Federal Register supplemental notice of data
  availability (58 FR 33790; June 21, 1993) and in response to
  public comments.  The alternatives reflect different emission
  rate cutoffs.  The final standard requires control of
  landfills with NMOC emissions above 50 megagrams per year.
  Other alternatives included the baseline  (no NSPS or EG), the
  proposed emission rate cutoff (150 Mg/yr), and an alternative
  with no emission rate cutoff.  Tables 1-1 and 1-2 present the
  emissions and cost impacts of the regulatory alternatives for
  the NSPS and EG  expressed as NPV and annualized values.
  1.3.4  Air Impacts
       The analysis of the impacts of the NSPS are based on the
  landfills projected to begin accepting waste over the first
  5 years of the standard.  For these landfills, the NPV of the
  baseline NMOC emissions are 160,000 Mg, and the NPV of the
  baseline methane emissions are 10.6 million Mg.  Of the
  roughly 900  landfills estimated to open during the first
  5 years, controls will be required at approximately 5 percent
  of the facilities.  The estimated NPV of  the emission
  reductions are 79,000 Mg  (50 percent) and 3.9 million Mg
   (37 percent) for NMOC and methane, respectively.  For existing
  landfills affected by the EG, the NPV of  the baseline NMOC
  emissions are 2.1 million Mg.  The NPV baseline methane

klk-85\0*                           1-54

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                                          1-56

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   emissions  are 120  million Mg.   Of  the  7,300  existing
   landfills,  controls  would be required  at  roughly 4  percent.
   The estimated NPV  of the emission  reductions are 1.1 million
   Mg (53  percent)  and  47  million  Mg  (39  percent)  for  NMOC  and
   methane, respectively.
        The NSPS and  EG are based  on  reductions of NMOC
                                                   • \
   emissions;  however,  landfill gas primarily consists of methane
   and carbon dioxide.   Although the  methane reductions achieved
   by these rules were  considered  as  ancillary  benefits in  the
           *
   analysis,  these  reductions  do have positive  global  climate
   change  impacts.  A potent greenhouse gas, methane is about
   20 times more effective at  trapping heat  in  the atmosphere
   than carbon dioxide  (over a 100 year time horizon).  Landfills
   are the largest  anthropogenic source of methane emissions in
   the U.S.,  constituting  about 40 percent of total emissions.
   President  Clinton  has committed to reducing  emissions of
   greenhouse gases to  1990 levels by the year  2000 and, in
   October 1993,  released  the  "U.S. Climate  Change Action Plan"
   for achieving that goal.  The MSW  landfills  NSPS and EG  are an
   important  component  of  the  Climate Change Action Plan because
   of the  significant greenhouse gas  reductions they provide.
   Other relevant components of the Climate  Change Action Plan
   include the EPA  Landfill Methane Outreach Program (hotline
   phone (202)  233-9042) to encourage more widespread  utilization
   of landfill gas  as an energy source, and  the Department  of
   Energy's Landfill  Methane Research Development  and
   Demonstration (RD&D) Program.   Taken together,  the  goal  of
   these Climate Change Action Plan actions  will lead  to methane
   reductions equivalent to over 6 million metric  tons of carbon
   in the  year 2000.
        Many  constituents  of NMOC  in  MSW  landfill  emissions are
   carcinogenic or  can  cause other adverse health  effects as
   discussed  in chapter 2  of the Background  Information Document
   for the proposed standards  (EPA-450/3-90-011(a), March 1991).
   The reduction in landfill emissions may result  in a reduction
klk-85\04                           1-57

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  of the risks from potential exposure to these constituents in
  the vicinity of the regulated landfills.
       The use of energy recovery devices for the control of MSW
  landfill emissions has the potential to reduce secondary air
  impacts from electric utility plants by reducing the energy
  requirements for these plants.  This is because the air
  impacts of electric energy generation from coal and oil-fired
  units are larger than those of LFG-fired energy generation.
  Landfill gas-to-energy projects are regarded as pollution
  prevention because energy is being recovered from a nonfossil
  fuel source while reducing the emissions of toxics, NMOC, and
  methane.  The EPA prepared an analysis  (Docket No. A-88-09,
  Item No. IV-B-5) that looks at the secondary air impacts and
  electricity generation due to the NSPS and EG.  If all
  landfills affected by the rule used energy recovery, the
  energy value available for electricity generation would be
  0.18 quadrillion BTU's (quads) in 2000 and 0.20 quads in 2010.
  To illustrate the significance of these potential energy
  values, comparisons were made using recent DOE statistics
  (i.e., Annual Energy Outlook with Projections to 2010, 1/93).
  The potential energy of landfill methane for sites affected by
  this rule is equal to 1.1 percent in 2000 and 1.2 percent  in
  2010 of the annual consumption of coal by U.S. electric
  utilities (i.e., 16.2 quads of coal were consumed by electric
  utilities in 1990).  The potential methane to be reduced from
  this rule compared to the annual consumption of petroleum  by
  U.S. electric utilities is 15 percent in 2000 and 16 percent
  in 2010  (i.e.,  1.23 quads of petroleum were consumed by
  electric utilities in 1990).
       There are  additional benefits associated with use of  this
  nonfossil fuel  source such as the potential offsets from
  electric power  plants.  The estimate of electricity production
  for the sites predicted to use energy recovery  (not including
  those  sites determined to be profitable or already utilizing
  energy recovery) is 2.7 kWh x 109 for the year  2000 and  2010.
  This would result in a reduction in emissions from electric

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   power plants  of greenhouse gases  such as  carbon dioxide (CC>2)
   and tropospheric ozone precursors,  criteria  pollutants
   including sulfur dioxide (802), nitrous oxides (NOX),  and
   carbon monoxide,  and toxics such  as mercury.   Assuming
   recovery of all the gas that is available, there is
   potentially a savings of 1.7 million tons of C(>2 «in 2000 and
   2010.  There  is also a potential  reduction of 0.5  thousand
   tons of SC>2 from landfills.  These  reductions may  be used by
   electric .utilities in reducing the  compliance cost to  meet the
   CAA requirements for SO2 emissions.  There is also a potential
   savings of 5  thousand tons of NOX although these emissions may
   be partially  offset by emissions  of NOX resulting  from the
   combustion of landfill gas.  Currently, data are insufficient
   to calculate  the net reductions.  The EPA has research
   underway through the Office of Research and  Development (ORD)
   to develop a  methodology for use  by States in considering the
   offset in emissions associated with landfill gas utilization
   projects so that the overall environmental benefits of these
   projects are  considered in permitting applications.
        Certain  by-product emissions,  such as NOX, CO, SOX» and
   particulates,  may be generated by the combustion devices used
   to reduce air emissions from MSW  landfills.   The types and
   quantities of these by-product emissions  vary depending on the
   control device.  However,  by-product emissions are very low
   compared to the achievable NMOC and methane  emission
   reductions.  Chapters 4 and 6 of  the proposal BID
   (EPA-450/3-90-01la, March, 1991)  present  additional
   information about the magnitude of  potential secondary air
   impacts.
   1.3.5  Other  Environmental Impacts
        1.3.5.1   Water.  Landfill leachate is the primary
   potential source of water pollution from  an  uncontrolled
   landfill.  Although there is not  sufficient  field test data to
   quantify the  effect of gas collection on  leachate composition,
   the amount of water pollutants present as NMOC in the  leachate
   may be reduced under these standards and  guidelines.

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       When LFG is collected, organics and water are condensed
  inside the header pipes of the gas collection system.  This
  water also contains NMOC and various toxic substances present
  in the LFG.  The pH of this condensate is normally adjusted by
  adding caustic at the landfill and then routing it to a public
  treatment facility.  This increases the amount of% these
  substances entering wastewater treatment plants.  There is
  insufficient data available to quantify this effect on the
  public water supply at this time.
       1.3.5.2  Solid Waste.  The final NSPS and EG will likely
  have little impact on the quantity of solid waste generated
  nationwide.  The required controls do not generate any solid
  waste.  However, the increased cost of landfill operation
  resulting from the control requirements may cause greater use
  of waste recycling and other alternatives to landfill
  disposal, leading to a decrease in landfill use.  However, is
  not possible to quantify such and impact at this time.
       1.3.5.3  Implications of the Rulemaking for Superfund.
  Municipal solid waste landfill sites comprise approximately
  20 percent of the sites placed by the EPA on the National
  Priorities List  (NPL).  Often, remedial actions selected at
  these sites include venting methane and volatile organic
  contaminants, and airborne emissions are treated  if determined
  necessary to protect human health and the environment.
       The final NSPS and EG may affect remedial actions under
  Superfund for MSW landfills.  Section 121(d)(2) of
  Comprehensive Environmental Response, Compensation, and
  Liability Act  (CERCLA) requires that remedies comply with the
  substantive standards of applicable and "relevant and
  appropriate" requirements  (ARAR's) of other environmental
  laws.   "Applicable" requirements specifically address a
  hazardous substance, pollutant, contaminant, remedial action,
  location, or other circumstance at a Superfund site.
  "Relevant and appropriate1' requirements are not legally
  applicable requirements, but may address problems or
  situations sufficiently similar to those encountered at the

klk-85\
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   Superfund  site  so  that  their use  is well  suited to  a
   particular site.   See 40  CFR 300.5  (55  FR 8666, 8814,  8817,
   March 8, 1990).
        These air  emission regulations will  apply to new  MSW
   landfills,  as well as to  those  landfills  that have  accepted
   waste since November 8, 1987.   This date  in  1987 is the date
   on which permit programs  were established under the Hazardous
   and Solid  Waste Amendments  of RCRA.   For  CERCLA municipal
   landfill remediations,  the  substantive  requirements of these
   regulations may be considered potential ARAR's based on site-
   specific factors.   These  NSPS and EG  may  be  applicable for
   those MSW  landfill sites  on the NPL that  accepted waste on or
   after November  8,  1987, or  that are operating and have
   capacity for future use.
        1.3.5.4 Energy.   Affected and designated landfills with
   NMOC emission rates of  50 Mg/yr or more are  required to
   install a  gas collection  system and control  device. The gas
   collection system  would require a relatively small  amount  of
   energy to  run the  blowers and the pumps.   If a flare is used
   for control, auxiliary  fuel should not  be necessary because of
   the high heat content of  LFG, commonly  1.86  x 107 J/scm
   (500 Btu/scf) or more.  If  a recovery device such as an
   I.e. engine, boiler, or gas turbine is  used, an energy savings
   would result.
        1.3.5.5 Control Costs and Economic  Impacts.   Nationwide
   annualized costs for collection and control  of air  emissions
   from new MSW landfills  constructed in the first 5 years of the
   standards  are estimated to  be $4  million.  The nationwide
   annualized cost of the  EG would be approximately $90 million.
   In comparison to other  solid waste-related regulations, the
   nationwide costs of the recently  promulgated RCRA subtitle D
   rule are estimated to be  $300 million per year and  the
   estimated  nationwide costs  of the MWC rules  promulgated in
   1991 are estimated to be  $170 million per year for  new
   combustors and  $302 million per year  for  existing combustors.
kli-85\0«                           1-61

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       For NMOC, the average cost effectiveness is $l,200/Mg and
  the incremental cost effectiveness of going from a 150 Mg/yr
  emission rate cutoff to a 50 Mg/yr cutoff is $2,900/Mg for new
  landfills.  For existing landfills, the average cost
  effectiveness is $l,200/Mg NMOC and the incremental cost
  effectiveness is $3,300/Mg NMOC.
       Preliminary economic analysis indicates that the annual
  cost of waste disposal may increase by an average of
  approximately $0.60 per Mg for the NSPS and $1.30 per Mg for
  the EG.  Annual costs per household would increase
  approximately $2.50 to $5.00 on average, when the household is
  served by a new or existing landfill, respectively.
  Additionally, less than 10 percent of the households would
  face annual increases of $15 or more per household as a result
  of the final EG.  However, the EPA anticipates that many
  landfills will elect to use energy recovery systems, and costs
  per household for those areas would be less.  The EPA has
  concluded that no households would incur severe economic
  impacts.  For additional information, please refer to the
  regulatory impact analysis  (Docket No. A-88-09, Item
  No. IV-A-7) and chapter 3.0 of this document.
klk-85\04                           1-62

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   2.0  SUMMARY AND RESPONSE TO PUBLIC COMMENTS RECEIVED ON THE
                  PROPOSED  STANDARDS AND GUIDELINES
   2.1  INTRODUCTION                                x
        The public comment period for the  proposed NSPS and EG
   was from May 30, 1991,  to August 1, 1991.   A total of
   60  letter's commenting on the proposed standards and guidelines
   were received.   Comments were provided  by industry
   representatives, governmental entities, environmental groups,
   and private citizens.  These comments have been recorded and
   placed in the docket for these rulemakings (Docket
   No.  A-88-09,  categories  IV-D and IV-G).  Category IV-G differs
   from category IV-D in that it documents correspondence
   received after the close of the comment period.   Table 2-1
   presents a listing of all persons  submitting written comments,
   their affiliation, and the recorded Docket Item No.  assigned
   to  each comment letter.
        In addition,  five persons presented oral comments on the
   proposed standards and guidelines  at a  public hearing held in
   Research Triangle Park on July 2,  1991.  A verbatim transcript
   of  the comments on the public hearing has been prepared and
   placed in Docket No. A-88-09,  Item No.  IV-F-1.   Category IV-F
   contains public comments pertaining to  the public hearing.
   Table 2-2 presents a listing of all persons presenting
   comments at the public hearing,  their affiliation,  and the
   docket item number assigned to each speaker.
        Comments made at the public hearing or submitted in
   writing are summarized and responses are provided in
   sections 2.2  through 2.19 of this  chapter.   The comments are
   grouped by subject areas, and the  organization of topics is
   similar to the  organization of the  proposal preamble for the
   new  source performance standards and guidelines (56  FR 24468;
   May  30,  1991).

klk-85\04                            2-1

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       TABLE 2-1.   LIST OF WRITTEN COMMENTERS ON THE PROPOSED
                     STANDARDS OF PERFORMANCE FOR MUNICIPAL
                             SOLID WASTE LANDFILLS


  Docket  item number3            Commenter and affiliation
  IV-D-1                  Mr. Edward W. Repa, Ph.D.
                          National Solid Wastes    *
                            Management Association
                          1730 Rhode Island Avenue, NW
                          Washington, D.C.   20036
           •
  IV-D-2                  Mr. David Armstrong
                          6544 Whispering Pines Drive
                          San Jose, California  95120

  IV-D-3                  Mr. Gregory W. Burrows, M.S.
                          Laboratory Director
                          FLI Environmental Services
                          446 Broad Street
                          Waverly, New York  14892-1445

  IV-D-4                  Mr. Christopher Frank
                          Resource Management Agency
                          Government Center
                          Administration Building, L #1710
                          800 South Victoria Avenue
                          Ventura, California  93009

  IV-D-5                  Mr. Charles Collins
                          Administrator, Air Quality Division
                          Department of Environmental Quality
                          Herschler Building
                          122 West 25th Street
                          Cheyenne, Wyoming  82002

  IV-D-6                  Mr. Mark H. Bobman
                          Assistant Director
                          Bristol Resource Recovery Facility
                          Operating Committee
                          75 Twining Street
                          Bristol, Connecticut  06010

  IV-D-7                  Mr. Gary L. Smith, P.E.
                          Vice President
                          Cummings and Smith, Incorporated
                          Post Office BOX 43073
                          Upper Montclair,  New Jersey  07043
kli-85\04                           2-2

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       TABLE 2-1.  LIST OF WRITTEN COMMENTERS ON THE PROPOSED
                     STANDARDS OF PERFORMANCE FOR MUNICIPAL
                             SOLID WASTE LANDFILLS
                                  (CONTINUED)


   Docket item number3           Commenter and affiliation
   IV-D-8                 Mr. Dale K. Phenicie      %
                          Manager of Environmental Affairs-North
                          Georgia-Pacific Corporation
                          Post Office Box 105605
                          Atlanta, Georgia  30348-5605

   IV-D-9                 Mr. Bob Van Deman, P.E.
                          Department of Solid Waste Management
                          Pinellas County
                          Board of County Commissioners
                          Post Office Box 21623
                          St. Petersburg, Florida  33742-1623

   IV-D-10                Mr. John W. LaFond
                          President
                          Quadrel Services, Incorporated
                          10075 Tyler Place #9
                          Ijamsville, Maryland  21754

   IV-D-11                Mr. Fred S. Kemp
                          Program Manager
                          International Fuel Cells
                          Post Office Box 739
                          South Windsor, Connecticut  06074

   IV-D-12                Mr. Edwin H. Seeger
                          Michael A. Poling
                          Prather Seeger Doolittle & Farmer
                          1600 M Street, NW, 7th Floor
                          Washington, D.C.  20036

   IV-D-13                Mr. William Juris
                          Division of Air Pollution Control
                          State of Ohio Environmental Protection
                            Agency
                          Post Office Box 1049
                          Columbus, Ohio  43266-0149

   IV-D-14                Mr. James H. McCoy
                          Total Petroleum, Incorporated
                          Denver Place North Tower
                          999 18th Street, Suite 2201
                          Denver, Colorado  80202-2492
kli-85\04                            2-3

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       TABLE 2-1.   LIST OF WRITTEN COMMENTERS ON THE PROPOSED
                     STANDARDS OF PERFORMANCE FOR MUNICIPAL
                             SOLID WASTE LANDFILLS
                                  (CONTINUED)


  Docket  item number3            Commenter and affiliation
   IV-D-15                 Mr. Lynne A. Plambeck    *
                          Co-Secretary Laser Coalition
                          Landfill Alternatives Save
                            Environmental Resources
                          23942 Lyons Avenue, Suite 103-353
                          Newhall, California  91321-2444

   IV-D-16                 Mr. Jerry T. Joseph
                          Senior Environmental Engineer
                          Westinghouse Electric Corporation
                          Resource Energy Systems Division
                          2400 Ardmore Boulevard
                          Pittsburgh, Pennsylvania  15221

   IV-D-17                 Mr. R. Darryl Banks
                          Deputy Commissioner
                          New York State Department of
                            Environmental Conservation
                          50 Wolf Road
                          Albany, New York  12233

   IV-D-18                 Mr. Rufus C. Young, Jr.
                          Burke, Williams & Sorensen
                          611 West Sixth Street, Suite 2500
                          Los Angeles, California  90017

   IV-D-19                 Mr. Michael J. Barboza, P.E.
                          Chairman
                          ASCE Task Committee on Air Toxics
                            Emissions
                          1015 15th Street, NW, Suite 600
                          Washington, D.C.  20005

   IV-D-20                 Mr. Patrick Kirsop, P.E.
                          Plan Review Unit Leader
                          State of Wisconsin
                          Department of Natural Resources
                          Post Office Box 7921
                          Madison, Wisconsin  53707-7921
klk-85\(H                            2-4

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       TABLE 2-1.  LIST OF WRITTEN COMMENTERS ON THE PROPOSED
                     STANDARDS OF PERFORMANCE FOR MUNICIPAL
                             SOLID WASTE LANDFILLS
                                  (CONTINUED)


   Docket item number3           Commenter and affiliation
                                                    •
   IV-D-21                Mr. Michael Baly, III
                          President
                          American Gas Association
                          1515 Wilson Boulevard
                          Arlington, Virginia  22209

   IV-D-22                Mr. Charles K. Weiss, Chief
                          Bureau of Sanitation
                          Baltimore County Government
                          Department of Public Works
                          111 West Chesapeake Avenue
                          Towson, Maryland  21204

   IV-D-23                Mr. Raymond F. Pelletier
                          Director
                          Office of Environmental Guidance
                          Department of Energy
                          Washington, D.C.  20585

   IV-D-24                Mr. David R. Wooley
                          Executive Director
                          Pace University School of Law
                          Center for Environmental Legal Studies
                          78 North Broadway
                          White Plains, New York  10603

   IV-D-25                Mr. H. Lanier Hickman, Jr., P.E.
                          Mr. Donald J. Borut
                          Mr. Larry E. Naake
                          Local Government Solid Waste Action
                            Coalition
                          Post Office Box 7219
                          Silver Spring, Maryland  20910

   IV-D-26                Mr. Richard L. Echols
                          Director of Operations, Gas Systems
                          Browning-Ferris Industries
                          Post Office Box 3151
                          Houston, Texas  77253
klk-85\04                            2-5

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       TABLE 2-1.   LIST OF WRITTEN COMMENTERS ON THE PROPOSED
                     STANDARDS OF PERFORMANCE FOR MUNICIPAL
                             SOLID WASTE LANDFILLS
                                  (CONTINUED)


  Docket  item  number3            Commenter and affiliation
   IV-D-27                 Ms. Sue M. Briggum
                          Director of Governmental Affairs
                          Waste Management of North America,
                            Incorporated
                          3003 Butterfield Road
                          oakbrook, Illinois  60521

   IV-D-28                 Mr. Thomas L. Connelly, P.E.
                          121 Orange Ridge Drive
                          Longwood, Florida  32779

   IV-D-29                 Mr. James K. Hambright
                          Bureau of Air Quality Control
                          Commonwealth of Pennsylvania
                          Department of Environmental Resources
                          Post Office Box 2357
                          Harrisburg, Pennsylvania  17105-2357

   IV-D-30                 Mr. Thomas A. Kraemer, P.E.
                          CH2M Hill
                          Seattle Office
                          777 108th Avenue, NE
                          Bellevue, Washington  98004

   IV-D-31                 Mr. Mark B. Beizer, P.E.
                          Vice President
                          SCS Engineers
                          3711 Long Beach Boulevard
                          Ninth Floor
                          Long Beach, California  90807

   IV-D-32                 Mr. Ralph E. Chandler
                          Executive Director
                          California Integrated Waste Management
                            Board
                          1020 Ninth Street, Suite 100
                          Sacramento, California  95814
klk-85\04                           2-6

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       TABLE 2-1.  LIST OF WRITTEN COMMENTERS ON THE PROPOSED
                     STANDARDS OF PERFORMANCE FOR MUNICIPAL
                             SOLID WASTE LANDFILLS
                                  (CONTINUED)


   Docket item number3           Commenter and affiliation
   IV-D-33                Ms. Deborah A. Sheiman
                          Resource Specialist
                          Ms. Marika Tatsutani
                          Research Associate
                          Natural Resources Defense Council
                          1350 New York Avenue, NW
                          Washington, D.C.  20005

   IV-D-34                Mr. John H. Gulledge
                          Solid Waste Management Department
                          County Sanitation Districts of
                            Los Angeles County
                          Post Office Box 4998
                          Whittier, California  90607-4998

   IV-D-35                Mr. Peter R. Karasik, P.E.
                          DEP/DSWM
                          101 Monroe Street, 6th Floor
                          Rockville, Maryland  20850-2589

   IV-D-36                Mr. Dan B. Magoun
                          Vice President
                          Environmental Affairs
                          6231 McBeth Road
                          Fort Wayne, Indiana  46809

   IV-D-37                Mr. Peter D. Venturini
                          Stationary Source Division
                          Air Resources Board
                          1102 Q Street
                          Post Office Box 2815
                          Sacramento, California  95812

   IV-D-38                Mr. Mohsen Nazemi, P.E.
                          Senior Engineering Manager
                          South Coast Air Quality
                            Management District
                          9150 Flair Drive
                          El Monte, California  91731
klk-85\04                            2-7

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       TABLE 2-1.   LIST OF WRITTEN COMMENTERS ON THE PROPOSED
                     STANDARDS OF PERFORMANCE FOR MUNICIPAL
                             SOLID WASTE LANDFILLS
                                  (CONTINUED)


  Docket  item number3            Commenter and affiliation
  IV-D-39                 Mr. Edward W. Repa, Ph.D. %
                          National Solid Wastes Management
                            Association
                          1730 Rhode Island Avenue, NW
                          Washington, D.C.  20036

  IV-D-40                 Mr. Larry D. Henry, P.E.
                          Maintenance Engineer
                          The City of Wichita
                          Department of Public Works
                          455 North Main Street
                          Wichita, Kansas  67202

  IV-D-41                 Mr. James C. Franklin
                          Manager, Flare Systems
                          IT McGill Pollution Control Systems
                          2700 East 51st Street
                          Tulsa, Oklahoma  74105

  IV-D-42                 Mr. Marvin Hempleman
                          Mr. Darrel A. Heider
                          Twin Falls County Board of County
                            Commission
                          425 Shoshone Street, North
                          Twin Falls, Idaho  83303-0126

  IV-D-43                 Ms. Jane Levine
                          Deputy Commissioner for Legal Affairs
                          The City of New York Department of
                            Sanitation
                          125 Worth Street, Suite 728
                          New York, New York  10013

  IV-D-44                 Mr. Francis J. Schwindt
                          State Department of Health and
                            Consolidated Laboratories
                          Post Office Box 5520
                          Bismarck, North Dakota  58502-5520
klk-85\04                           2-8

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     TABLE 2-1.   LIST  OF WRITTEN  COMMENTERS ON THE  PROPOSED
                   STANDARDS  OF PERFORMANCE FOR MUNICIPAL
                           SOLID  WASTE LANDFILLS
                                (CONTINUED)


Docket item number3            Commenter and  affiliation
IV-D-45                 Ms.  Marsha McLean        s
                        President
                        S.C.V.  Canyons Preservation Committee
                        24519 Breckenridge Place
                        Newhall,  California  91321

IV-D-46                 Mr.  James C.  Street
                        Commissioner  of Public Works
                        Lexington-Fayette Government Building
                        200  East  Main Street
                        Lexington,  Kentucky  40507

IV-D-47                 Ms.  Jane  Levine
                        Deputy Commissioner for Legal Affairs
                        The  City  of New York Department of
                          Sanitation
                        125  Worth Street,  Suite 728
                        New  York,  New York  10013

IV-D-48                 Mr.  Edward Peterson
                        Environmental Activities Staff
                        General Motors Corporation
                        General Motors Technical Center
                        30400 Mound Road
                        Warren, Michigan  48090-9015

IV-D-49                 Mr.  Edward W.  Elam
                        City Manager
                        Manager Lucas Monroe County Landfill
                        City of Chariton
                        115  South Main Street
                        Chariton,  Iowa  50049

IV-D-50                 Ms.  Linda G.  Stuntz
                        Deputy Under  Secretary
                        Policy, Planning and Analysis
                        Department of Energy
                        Washington, D.C.   20585
                              2-9

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       TABLE 2-1.   LIST OF WRITTEN COMMENTERS ON THE PROPOSED
                     STANDARDS OF PERFORMANCE FOR MUNICIPAL
                             SOLID WASTE LANDFILLS
                                  (CONTINUED)


   Docket  item  number3            Commenter and affiliation
   IV-D-51                 Mr. William Juris        '%
                          Division of Air Pollution Control
                          State of Ohio Environmental Protection
                          Agency
                          Post Office Box 1049
                          Columbus, Ohio  43266-0149

   IV-D-52                 Mr. Brad Jones
                          Saguache County Administrator
                          Saguache County
                          Land Use Department
                          Post Office Box 326
                          Saguache, Colorado  81149

   IV-D-5^                 Mr. Michael E. McDaniel, R.s.
                          Rockingham County Department of Public
                            Health
                          Rockingham County Governmental Center
                          Route 8, Box 701-J
                          Reidsville, North Carolina  27320

   IV-D-54                 Mr. Leonard D. Verrelli
                          State of Alaska
                          Department of Environmental
                            Conservation
                          Division of Environmental Quality
                          Post Office Box O
                          Juneau, Alaska  99811-1800

   IV-D-55                 Mr. Michael R. Lake
                          Chief of Engineering
                          Air Pollution Control District
                          9150 Chesapeake Drive
                          San Diego, California  92123-1095

   IV-D-56                 Mr. George N. Kay a
                          Director of Public Works
                          County of Maui
                          Department of Public Works
                          200 South High Street
                          Wailuku, Maui, Hawaii  96793
kDc-85\0*                           2-10

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       TABLE 2-1.  LIST OF WRITTEN COMMENTERS ON THE PROPOSED
                     STANDARDS OF PERFORMANCE FOR MUNICIPAL
                             SOLID WASTE LANDFILLS
                                  (CONCLUDED)


   Docket item number3           Commenter and  affiliation
   IV-D-57                Mr. Jonathan Greenberg    *
                          Browning-Ferris Industries,
                            Incorporated
                          1150 Connecticut Avenue,  N.w.
                          Suite 500
                          Washington, D.C.  20036

   IV-G-1                 Ms. Dawn M. Campbell
                          The Solid Waste Association  of
                            North America
                          Post Office Box 7219
                          Silver Spring, Maryland   20910

   IV-G-2                 Senator Joseph I. Lieberman
                          Senate Office Building
                          Washington, D.C.  20510

   IV-G-3                 Mr. Lanier Hickman, Jr.,  P.E.,  D.E.E.
                          Executive Director
                          The Solid Waste Association  of
                            North America
                          Post Office Box 7219
                          Silver Spring, Maryland   20910
kl*-85\04                           2-11

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    TABLE 2-2.  LIST OF PUBLIC HEARING SPEAKERS ON THE PROPOSED
                     STANDARDS OF PERFORMANCE FOR MUNICIPAL
                             SOLID WASTE LANDFILLS


  Docket  item numbera            Commenter and affiliation
   IV-F-3                  Mr. Edward W. Repa, Ph.D.
                          National Solid Wastes Management
                            Association
                          1730 Rhode Island Avenue, NW
                          Washington, D.C.  20036

   IV-F-4    *              Mr. Robert Peters
                          The Solid Waste Association of
                            North America
                          Post Office Box 7219
                          Silver Spring, Maryland  20910

   IV-F-5                  Mr. Jeff Douglas
                          Waste Management, Incorporated
                          1155 Connecticut Avenue, N.W.
                          Suite 800
                          Washington, D.C.  20036

   IV-F-6                  Mr. Rick Oakley
                          Mr. Richard EchoIs
                          Browning-Ferris Industries,
                            Incorporated
                          1150 Connecticut Avenue, N.W.
                          Suite 500
                          Washington, D.C.  20036
   aThe  docket number  for this  project is  A-88-09.   Dockets are
    on file  at the  EPA Headquarters in Washington,  D.C.
klk-85\0«                           2-12

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        On June 21,  1993,  the EPA published a notice in the
   Federal Register (58 FR 33791)  providing information on
   additional data being used in the development of the final
   NSPS and EG for MSW landfills.   The additional data that were
   made available for public comment included:  (1) An updated
   data base of site-specific landfill information from which k,
   L0 pairs are calculated and CNMQC values are selected (the k,
   Lo data base); (2)  revised modeling methodologies used to
   calculate k values which are then used to estimate nationwide
   impacts; and (3)  the incorporation of energy recovery in the
   modeling of nationwide impacts.  The public comment period for
   this notice was from June 21, 1993, to July 21, 1993.  A total
   of seven letters commenting on the additional data were
   received from industry representatives,   governmental
   entities,  academia, and a private citizen.   These comment
   letters have been recorded and placed in the docket for these
   rule makings (Docket No.  A-88-09, Category IV-L).  Table 2-3
   presents a listing of all persons submitting written comments,
   their affiliation,  and the recorded docket item number
   assigned to each comment letter.   The comments that were
   submitted are integrated with the comments and responses to
   the proposed NSPA and EG provided under sections 2.3 through
   2.19 of this chapter.
   2.2  GENERAL COMMENTS
   2.2.1  Definitions
        Comment;  Two commenters reguested that definitions of
   the terms "enclosed combustor"  and "sufficient extraction
   rate" be included in the definitions section,  S 60.751.
        Response:   After considering the commenters' suggestions,
   the EPA added definitions in $  60.751 for the terms "enclosed
   combustor" and "sufficient extraction rate."
        Comment;  One industry commenter (IV-D-27) recommended
   changing the following  definitions in the proposed regulations
   to make them consistent with existing solid waste (RCRA)
   definitions:  "commercial solid waste";  "controlled landfill";
kllc-85\04                           2-13

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      TABLE 2-3.  LIST OF WRITTEN COMMENTERS ON THE NOTICE OF
                    AVAILABILITY FOR THE PROPOSED STANDARDS
                          OF PERFORMANCE FOR MUNICIPAL
                              SOLID WASTE LANDFILLS


  Docket  item number3            Commenter and affiliation
  IV-L-01                 Mr. Kurt W. Rieke
                          Assistant General Counsel
                          Ogden Projects, Incorporated
                          Post Office Box 2615
                          Fairfield, New Jersey   07007-2615

  IV-L-02                 Mr. H. Lanier Hickman,  Jr.
                          Executive Director
                          The Solid Waste Association
                             of North America
                          Post Office Box 7219
                          Silver Spring, Maryland 20910-7219

  IV-L-03                 Mr. Kurt W. Rieke
                          Assistant General Counsel
                          Ogden Projects, Incorporated
                          Post Office Box 2615
                          Fairfield, New Jersey   07007-2615

  IV-L-04                 Mr. Thomas L. Connelly
                          121 Orange Ridge Drive
                          Longwood, Florida   32779

  IV-L-05                 Dr. Ramana K. Rao
                          Senior Engineer
                          Montgomery County,  Department
                             of Environmental  Protection
                          101 Monroe Street
                          Rockville, Maryland 20850

  IV-L-06                 Mr. Bharat Mathur
                          Chief, Bureau of Air
                          State of Illinois
                          Environmental Protection Agency
                          2200 Churchill Road
                          Springfield, Illinois   62794-9276

  IV-L-07                 Mr. David R. Wooley
                          Executive Director
                          Pace University School  of Law
                          Center for Environmental Legal Studies
                          78 North Broadway
                          White Plains, New York  10603
kli-85\04                           2-14

-------
   "design capacity"; "industrial solid waste";  "municipal solid
   waste landfill"; and, "sludge."
        Another conunenter (IV-D-32)  indicated that the definition
   of "controlled landfill" is not clear and should be restated
   to say that "controlled landfills" are those  landfills with
   operating collection and control systems in place.
   Furthermore the commenter requested the term  "construction
   permit" in the definition for design capacity be changed to
   "operating permit."
        Response;  The terms applicable to this  regulation are
   defined in $ 60.751.  The definitions for "commercial solid
   waste", "industrial solid waste",  and "sludge" are  identical
   to the definitions contained in the RCRA regulations.  The
   terms "controlled landfill" and "design capacity" are defined
   in this MSW landfill NSPS regulation, but not under RCRA.  The
   term "municipal solid waste landfill" is defined within these
   regulations to assist in determining applicability  with the
   NSPS; RCRA defines the term "municipal solid  waste  landfill
   unit" for applicability under RCRA.
        As for the definition of "controlled landfill," a
   landfill is considered controlled at the time a collection and
   control system design plan is submitted.   Thus, a collection
   and control system does not have to be operational  for a
   landfill to be controlled under this definition.  The
   definition of design capacity has been revised to state that
   the design capacity will be specified in the  construction or
   operating permit.   If the maximum design capacity is not
   specified in the permit,  the reporting requirements now allow
   it to be calculated using good engineering judgment.
        Comment;  One commenter (IV-D-27)  suggested that the EPA
   eliminate the use of the term "permanently closed landfill"
   within the preamble discussion since the definition of "closed
   landfill" means essentially the same thing.   Another commenter
   (IV-D-32)  indicated that the definition of "closed  landfill"
   in the proposed regulation differs from their State's
   definition of "landfill closure,"  and also does not address

klk-85\04                          2-15

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  the common practice of closing discrete sections of the
  landfill as they become full.  The commenter noted that these
  units are typically closed according to an approved plan and
  are no longer subject to new regulations in his State.  The
  commenter requested clarification of this issue and suggested
  that certification by a knowledgeable engineer or geologist
  occur prior to considering a landfill closed.
       Response:   The definition of "closed landfill" contained
  in the final regulation means a landfill in which no
  additional solid wastes will be placed in the future.  If
  additional solid wastes need to be placed in the landfill, a
  notification of modification [5 60.7(a)(4)] must be filed and
  the landfill will no longer be considered a closed landfill.
  In order to be considered closed, a landfill must also meet
  the criteria of 40 CFR 258.60.  The term "permanently closed
  landfill" is not contained in the preamble to the final
  regulation.
       Although discrete sections of a landfill may be certified
  as closed for purposes of RCRA, these sections are
  contributing to the overall NMOC emission rate of the entire
  landfill and remain potentially affected by this regulation
  because the overall NMOC emission rate is the basis for
  applicability under these regulations.
       Comment:  One commenter (IV-D-39) requested that the term
  "readily accessible" records be defined.
       Response;  Records in S 60.758 of the final NSPS can be
  either paper or electronic records.  Host records must be kept
  for 5 years.  The final rule specifies that these records may
  be kept either on-site or off-site if they are retrievable
  within 4 hours.  A few types of records must be kept readily
  accessible for the life of the landfill or equipment.  These
  records may also be maintained either on-site or off-site.
  2.2.2  Wording of the Standards
       Comment;  Several commenters  (IV-D-23, IV-D-25, IV-D-27,
  IV-D-32, IV-D-34) noted places within the Federal Register
  notice that appeared to contain typographical errors or

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   erroneous cross references.  Two commenters (IV-D-23,  IV-F-6)
   noted that S 60.753 of the proposed NSPS refers to the methane
   generation rate constant as 0.02/yr and S 60.758 refers to the
   methane generative rate as 0.2/yr.
        Response;  The final regulations were reviewed and
   typographical errors and erroneous cross references were
   corrected.
        Comment;  Two commenters (IV-D-22, IV-D-32) asked for
   clarification about the term "DM in S 60.753(a)(3)(ii)(A),
   Tier 2, of the proposed NSPS, wondering if it is the same D
   defined in Method 2E.
        Response;  The commenter was referring to an equation
   contained in Tier 2 at proposal.  This equation was removed
   from Tier 2, in an effort to simplify the Tier 2 requirements.
   In the final regulation, Tier 2 requires the owner or operator
   to determine the NMOC concentration using a specified sampling
   procedure.  The regulation requires at least 2 sample probes
   to be installed per hectare of landfill surface that has
   retained waste for at least 2 years.  Areas of nondegradable
   solid waste should be avoided when installing the sample
   probes.  No more than 50 sample probes are required,
   regardless of the size of the landfill.  If more than
   50 samples are taken, then all samples must be used in
   determining the NMOC emission rate.  The landfill owner or
   operator will collect and analyze one sample of landfill gas
   from each probe to determine the NMOC concentration using
   Method 25C.
        Comment;  One commenter (IV-D-4) indicated that the
   nomenclature for CNMQC should be referred to in a more
   consistent manner throughout the proposed regulation.   The
   commenter further maintained that references to NMOC
   concentrations and nomenclature be stated as ppmC (carbon
   equivalent) as in Method 25C.  The commenter asserted that if
   the conversion factors are changed to consistently reflect the
   carbon equivalent (instead of hexane as it is stated)  then
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  changes within the regulation will need to be made to reflect
  this.
       Response:  The EPA has reviewed the regulation between
  proposal and promulgation to remove any ambiguity regarding
  the use of the term Cjnjoc-  Tne conversion factors in the
  final regulation for NMOC consistently reflect the hexane
                                                   • *
  equivalent.
       Comment::  One commenter (IV-D-38) suggested that "or
  within 1 year after necessary State and local permits are
  issued, whichever is later" be added to S 60.752(b)(2)(ii).
  This paragraph requires the installation of LFG collection and
  control systems within 1-1/2 years of design plan submittal or
  notification of intent to install a collection and control
  system.  The commenter stated that the permit process is very
  time consuming.
       Response;  The EPA considers the timeframes provided  in
  the final NSPS and EG to be reasonable, based on section 111
  concerns.  As stated in the preamble to the proposed
  regulations, the time allowed between submittal of the design
  plan and installation of the collection and control system
  takes into consideration necessary lead time for obtaining and
  installing the system components.  Whether or not a particular
  landfill must also go through a permitting process and how
  time consuming that process may be will vary from State to
  State, and this is best dealt with at the State  level when the
  plans for implementing the NSPS and EG are developed.
  Section 2.14.1 contains additional information on compliance
  times.
       Comment:  One commenter  (IV-D-19) indicated the
  regulation should clearly state that 98 percent  emission
  reduction refers to reduction of NMOC collected  by the gas
  collection system, not 98 percent of all  landfill-generated
  gases.
       Response;  All references to 98 percent emission
  reduction within the NSPS and EG refer to reduction of NMOC  in
  the collected gas.

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        Comment;   One commenter (IV-D-26)  indicated that the RIA
   should be revised for the final rule.   The commenter stated
   that the conclusions in the RIA are sometimes not referenced
   and that the document contains some careless and biased text.
   The commenter also suggested that the revised edition should
   disclaim the first edition.
        Response:   The RIA has been reviewed and revised in
   conjunction with the final rule.  The final RIA is included in
   Docket A-88-09  as Item No. IV-A-7.  The EPA has made every
            •
   effort to address pertinent issues in a fair and unbiased
   manner.
   2.3  SELECTION  OF THE SOURCE CATEGORY
   2.3.1  Statutory Authority to Regulate
        Comment;   One commenter (IV-D-06)  contended that RCRA
   subtitle 0 is the proper arena for addressing MSW landfill
   emissions and that this standard should not come under
   section  111 of  the CAA.  A second commenter (IV-D-18),
   however, expressed agreement with the EPA in listing MSW
   landfills as a  source category under Act section lll(b)(1)(A).
   The second commenter (IV-D-18)  agreed with the proposed
   regulation that for the purposes of ascertaining the NMOC
   emission rate and design capacity, the entire landfill and all
   its emissions should be considered one landfill, i.e, the
   affected facility.
        Two commenters (IV-D-5, IV-D-55)  argued that MSW
   landfills should be regulated under section 112, the NESHAP
   program, rather than under section ill.  One commenter
   (IV-D-55)  contended that air emission regulations in that
   State were the  result of concern for toxic air impacts,  health
   concerns and fire hazards that had no particular correlation
   to landfill size.   The commenter (IV-D-55)  cited an example of
   a school playground built on top of a closed landfill, where
   students and teachers had reported illnesses correlating with
   emission episodes.  The commenter (IV-D-55)  noted a variety of
   section  112 HAP's that are often found  in LFG.
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       Two conunenters  (IV-D-5, IV-D-44) stated that because NMOC
  exist in relatively  insignificant amounts in their States, the
  proposed regulation  would be an unnecessary burden and strain
  on scarce resources.  One of these conunenters  (IV-D-44)
  maintained that landfill regulations should fall under the
  control of State and local air pollution agencies.  Another
  commenter  (IV-D-42)  stated that methane gas and/or leachate
  has never been produced in significant amounts in their area,
  and did not appreciate a mandatory "methane gas regulation."
       Response:  The  regulation of MSW landfill emissions
  originally was considered during deliberations under a RCRA
  subtitle D rulemaking.  In 1987 the Administrator decided to
  regulate these emissions under the authority of the Clean Air
  Act.  After further  consideration, the EPA announced in the
  Federal Register on  August 30, 1988  (53 FR 33314) their
  decision to regulate MSW landfill emissions under section 111
  of the CAA.
       As discussed  in the proposal preamble, section 111 NSPS
  and EG are issued  for categories of sources which cause, or
  contribute significantly to, air pollution which may
  reasonably be anticipated to endanger public health or welfare
   (56 FR 24468; May  30, 1991).  Evidence from the EPA and State
  studies show that  MSW landfills release air pollutants that
  have adverse effects on both public health and welfare.  For
  this reason, the EPA chose to regulate MSW landfill emissions
  under section 111.
       The RCRA subtitle D establishes a framework  for
  controlling the management of nonhazardous solid  waste.
  Because the intent of this rule is to regulate emissions of
  landfill gas, and  not solid waste, this regulation has been
  developed  under the  CAA instead of under RCRA.  Some
  requirements  in the  RCRA subtitle D regulation are referenced
  within the NSPS and  EG and are necessary to achieve compliance
  with these regulations.
       The CAA  as amended  (1990 Amendments) revised the  approach
  for regulating HAP emissions under section 112 and requires

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   that the EPA publish a list of categories of sources having
   the potential to emit 10 or 25 tons/yr in the aggregate of any
   HAP listed in section 112.   MSW landfills are a source of such
   HAPs and therefore were included on the source category list.
   MSW landfills not emitting above the regulatory cutoff under
   the NSPS and guidelines may still meet the section 112
                                                   • x
   criteria.  Thus, the HAP emission potential of such landfills
   and the need for control of HAP's from municipal landfills
   will be evaluated in the future as part of that program.
   Additionally, State and local governments may address
   site-specific issues under their own air toxics programs.
        Despite the listing under section 112,  it was decided to
   continue with the section ill regulations because  they address
   the range of health and welfare concerns related to landfill
   gas emissions.   Furthermore,  because they have already been
   proposed, section 111 regulations can be promulgated more
   quickly than section 112 regulations thereby achieving
   benefits of earlier control at landfills with NMOC emissions
   above the cutoffs.   In response to commenters who  are
   concerned about the burden of the regulation,  the  final
   regulation includes both a design capacity exemption and an
   emission rate cutoff to determine if controls are  required
   thereby focusing control efforts on those landfills where the
   greatest emission reductions can be achieved and control is
   most reasonable.  This will greatly reduce the burden on small
   landfills who would incur high costs if they were  required to
   apply controls,  but would see only small emission  reductions.
        The proposed regulations are not methane gas  regulations.
   The designated pollutant of concern is MSW landfill emissions
   because it has been determined to be a threat to the
   environment and public health.   The group of compounds, NMOC,
   was chosen as the surrogate pollutant for landfill emissions
   because NMOC includes those LFG constituents of most concern
   to the environment and public health.   Only landfills emitting
   NMOC greater than the regulatory cutoff are required to
   install controls.

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  2.3.2  Health and Welfare Concerns
       Cop^fn't;  A number of commenters addressed the EPA's
  consideration of the five areas of concern regarding potential
  adverse health and welfare effects of air emissions from MSW
  landfills.  The five major effects of MSW landfill air
  emissions are:  (1) human health and vegetation effects caused
                                                   •»
  by ozone formed from nonmethane organic compound emissions,
  (2) carcinogenicity and other possible noncancer health
  effects associated with specific MSW landfill emission
            •
  constituents,  (3) green house effects from methane emissions,
  (4) explosion hazards, and  (5) odor nuisance.
       Three commenters  (IV-D-26, IV-D-39 and IV-F-3, IV-F-4)
  stated that the five concerns have not been quantified or
  properly justified in  the EPA's analysis.  Two commenters
  (IV-D-26, IV-F-4) stated that these five concerns can better
  be addressed using a performance standard.
       Several commenters (IV-D-2, IV-D-17, IV-D-18, IV-D-45,
  IV-D-55, IV-L-1) expressed concern for the effects MSW
  emissions can have on  public health.  One commenter  (IV-L-1)
  contended that the proposed NSPS was insufficiently inclusive
  and stringent to protect public health and the environment.
  The commenter  (IV-L-1) requested that the EPA reconsider
  whether the CAA compliance and health risk implications have
  been addressed by the  proposed NSPS.  Two of the commenters
  (IV-D-18, IV-D-45) argued that LAER and not BDT should be  used
  in nonattainment areas to better protect public health.
  Another commenter  (IV-D-55) was concerned that the proposed
  regulations would divert funding from small, more hazardous
  landfills to larger, remote landfills which are less hazardous
  to public health.  A third commenter  (IV-D-2) suggested
  increasing the stringency of standards for landfills located
  3 or fewer miles from  a residence.
       One commenter  (IV-D-19) requested that basic information
  regarding the magnitude of effects a landfill and its
  emissions may have on  the surrounding land area be considered
  in the final regulation because it could either justify

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   additional controls or justify the reduction of controls.
   Another commenter (IV-D-39)  added that the proposal BID
   provides information on the effects of ozone on laboratory
   animals and vegetation, but does not quantify the role
   landfill air emissions play in endangering public health or
   welfare.  Therefore, the contribution of landfill air
                                                   •»
   emissions to ozone formation and its resulting impact on the
   environment and human health cannot be determined.  Also,  the
   conunenter argued that existing studies have shown that the
            •
   carcinogenic risks associated with landfill emissions are
   actually very low (1 x 10~6 to 1 x 10~8) and that such low
   risk sources are not typically regulated.
        The commenter (IV-D-39) stated that no data are presented
   on the contribution and effects that landfill-derived methane
   plays in the alleged "global warming" process.  The commenter
   stated that the existing data suggest that landfills as a
   methane source are a small component of the total methane
   generated and released into the atmosphere.
        Another commenter (IV-D-17) was concerned with the danger
   imposed on nearby residential areas by the existence of toxic
   organic compounds in LFG and the threat of explosion due to
   volatile gases.
        The commenter (IV-D-39) stated that although the
   explosive hazard of methane migration into on-site and off-
   site buildings is well documented,  the control of methane for
   explosive hazards is already addressed in subtitle D of RCRA.
   Therefore,  this regulation will do little to reduce the
   potential of such hazards since appropriate controls are
   already mandated under existing law.
        The commenter (IV-D-39) stated that odor control
   practices are presently being addressed in the revisions to
   RCRA subtitle D.   The commenter also asserted that the
   technical data presented and the analysis performed do not
   clearly justify the regulation.  Also,  the commenter critiqued
   the five areas of concern identified by the EPA as
   justification for the standard.

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       The commenter (IV-D-39) stated that the courts have
  rightfully insisted that a variety of factors, such as costs,
  health and environmental impacts, nonair quality impacts, and
  energy requirements be evaluated in formulating new source
  standards pursuant to section 111.  The commenter asserted
  that the proposed standards are inconsistent, both with the
  expressed terms of section ill and the regulations promulgated
  thereunder.
       Response;  The EPA is regulating MSW landfill emissions
           •
  to address threats to public health and welfare posed by
  landfill emissions on a nationwide basis.  Recognizing that
  individual MSW landfills contribute to these nationwide health
  and welfare concerns, the EPA has fully considered these
  issues for this section 111 rulemaking.  The EPA addressed the
  five areas of concern to public health and welfare to the
  extent possible using the available sources of information at
  proposal.  The proposal preamble, BID, and RIA provided the
  basis for addressing these concerns as well as discussions on
  cost benefit analysis.
       As stated in the proposal preamble  (see 56 FR 24469;
  May 30, 1991), NSPS implement section lll(b) of the CAA and
  are issued for categories of sources which cause or contribute
  significantly to air pollution which may reasonably be
  anticipated to endanger public health or welfare.  In
  addition, an NSPS requires these sources to control emissions
  to the level achievable by BDT considering costs and any
  nonair quality health and environmental  impacts and energy
  requirements.  As such, the proposed standards conform to
  section 111 of the CAA.  All of the relevant factors were
  considered and the EPA's decisions regarding these factors
  were summarized in the preamble to the proposed NSPS
   (56 FR 24468; May 30, 1991).
       Section 111 standards deal with emissions of concern
  through establishing technology-based, not risk-based,
  standards.  The level of control required under the
  section 111 NSPS program is BDT.  The NSPS may assist States

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   in achieving the NAAQS,  but this is not the focus of the NSPS.
   States can institute more stringent requirements for any
   source to address State or local issues, including provisions
   requiring the use of LAER.  Under the NSR program, either BACT
   in attainment areas or LAER in nonattainment areas are
   determined on a site-specific basis.   The BACT or LAER must,
                                                   • *
   at a minimum, be equivalent to the BDT under any applicable
   NSPS, but may also be more stringent.
        The commenter concerned about smaller, more hazardous
            •
   landfills focussed on air toxics.  As discussed in the
   previous paragraph, air toxics at landfills emitting above the
   regulatory cutoff will be reduced by these regulations, and
   the EPA also intends to address HAP emissions at MSW landfills
   specifically under section 112.  Additionally, the inclusion
   of MSW landfill emissions on the PSO significance list and the
   promulgation of these NSPS and guidelines should provide
   funding relief to State  air program boards.  Title V of the
   CAA required that States collect fees from all sources subject
   to regulation under the  CAA,  and the EPA promulgated this
   operating permit program on July 21,  1992 (57 FR 32250).
        As stated in the preamble to the proposed regulations,
   landfills emit methane,  which has been identified as a
   greenhouse gas contributing to global climate change.  Because
   the rate and magnitude of these changes are uncertain, a
   quantitative assessment  of climate change impacts was not
   performed.  However, methane reductions were quantified, and
   the NSPS and guidelines  together will reduce methane emissions
   by over 47 million Mg (expressed as NPV).  The President's
   1993 Climate Change Action Plan calls for the promulgation of
   the landfill gas rule.
        Explosion hazards for methane at the boundary of the
   landfill are addressed directly under RCRA.  This regulation
   would supplement RCRA and reduce the threat of explosions all
   over the landfill site,  as well as offsite at controlled
   landfills through the destruction of LFG.  Hazardous air
   pollutants from landfills would also be reduced through these

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  regulations, and municipal landfills have also been listed for
  future regulatory development under section 112 of the CAA
  (see 57 FR 31576; July 16, 1992).
       Because of the difficulty in describing HSW landfill
  emission levels that can be causally linked to the risk of
  fire or explosion, the EPA did not attempt to quantify these
                                                  ' %
  effects.  Chapter 2 of the proposal BID describes these
  effects in greater detail.  Although RCRA addresses explosion
  hazards, not all landfills will be subject to RCRA.  Explosion
           •
  potential will be reduced at all landfills that must install
  collection and control systems as a result of these
  regulations.  All of these concerns, whether addressed
  qualitatively or quantitatively, contributed to the EPA's
  decision to regulate MSW landfills under section 111 of the
  CAA.
       Because odor perception and impact is subjective, it  is
  difficult to quantify the degree of unpleasantness of odor.
  Therefore, the EPA has addressed the adverse effects of odors
  qualitatively in its analysis.  Because NMOC are a precursor
  to ozone, the NSPS and EG should provide a reduction in ozone
  formation.  However, the effect of NMOC on ozone formation has
  not been accurately quantified and has only been addressed
  qualitatively.
       The commenter asked that the effects one particular
  existing MSW landfill has on surrounding areas be considered
  in the regulation.  However, NSPS under section 111 of the CAA
  must require the application of BDT that addresses public
  health and welfare concerns at all affected landfills.  The
  BDT established for this rulemaking requires all affected
  landfills to install collection and control systems if their
  calculated NMOC emission rates exceed the emission rate
  cutoff.  Also, State and local agencies have the flexibility
  to consider any site-specific public health and welfare
  concerns in developing their own regulatory and permitting
  programs and establishing additional control requirements.
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                  One comment er (IV-L-1)  encouraged the EPA to
   immediately begin to conduct studies in preparation for the
   8-year review.   The commenter discussed pollutant-specific
   cancer risks of benzene and vinyl chloride.
        Response ;    The section 111 standards are technology
   based standards and as such do not address specific health
   risk.  While section 111 requires periodic review* of
   standards,  that review does not include health risk
   estimation; rather, it addresses whether the standards reflect
   BDT,  considering technology advances and other factors.  The
   commenter may be confusing the section 111 (NSPS)  and
   section 112 (NESHAP)  programs.  The CAA requires a review of
   residual risk 8 years after NESHAP are promulgated under
   section 112.  This provision does not apply to NSPS.
   Municipal landfills are listed as a source category that emits
   hazardous air pollutants and NESHAP will be developed in the
   future .
   2.4  SELECTION OF THE AFFECTED AND DESIGNATED FACILITIES
        Comment :   Three commenters (IV-D-17,  IV-D-39,  IV-D-48)
   cautioned the EPA that controlling landfills which have
   accepted waste after November 8, 1987 and which may have
   closed prior to May 30, 1991 is unfair,  and would pose an
   economic burden, because these landfills will have no means to
   raise the funds needed for installation of collection and
   control systems.  One of the commenters (IV-D-17)  suggested
   that  a requirement be included in the final rule for an
   economic and fiscal analysis to determine the feasibility of
   applying the emission guidelines "retroactively."   Given that
   a retroactive cutoff date was set,  the commenter suggested
   that  an alternative cutoff date, ranging from 1965 to 1970,
   might be appropriate for landfills large enough to warrant
   regulation,  because such landfills might still be producing
   NMOC.
        Two commenters (IV-D-26, IV-D-39)  recommended that an
   existing facility be defined as a facility that had received
   waste on or after May 30, 1991,  the date of proposal, instead

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  of November 8, 1987.  One of the commenters  (IV-D-26) stated
  that the costs for compliance with the November 8, 1987 cutoff
  date are significant.  One of the commenters  (IV-D-39) argued
  that owners of closed facilities historically have not been
  required by the EPA to implement controls and that the
  environmental benefit gained by the inclusion of. Bolder
  landfills would be much less than the benefit of controlling
  open landfills because older closed landfills typically have
  emission Jevels that are much lower than newer sites.
       The commenter  (IV-D-39) asserted that locational data for
  these facilities  is not readily available and would be
  difficult to obtain because most States did  not maintain  such
  records despite the requirement of the 1984  RCRA amendments.
  Additionally, the commenter reported that a  comparison of
  recent surveys shows that States were not capable of reporting
  the same data consistently and that differences between data
  sets were sometimes as great as 100 facilities.
       Response;  As discussed in section IV.D of the proposal
  preamble under "Selection of the Affected and Designated
  Facilities," the  EPA requested comment about the ability  of
  States to identify those landfills which may have closed  after
  November 8, 1987, and the appropriateness of this date as a
  cutoff for applicability.  The EPA typically does not
  establish operating standards through section lll(d) of the
  CAA for sources no  longer operating.  However, during the
  development of these standards and guidelines, the EPA found
  that a typical landfill is likely to generate landfill gas at
  a maximum rate at, or soon after, closure and that the
  generation rate would steadily decline thereafter.
       A significant number of landfills have  closed after
  November 8, 1987, prior to 1991, and may still have emissions
  above the regulatory cutoff that pose a risk to public health
  and welfare.  For this reason, the EPA considers it
  appropriate to regulate these landfills under section lll(d)
  of the CAA.
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     Faced with the administrative and policy complexities of
regulating closed facilities, the EPA looked for an approach
that was likely to lead to reasonable success in reducing
emissions without establishing unreasonable requirements.
     The Hazardous and Solid Waste Amendments to RCRA of 1984
required States to establish a permit program or other system
of prior approval to ensure that facilities receive household
hazardous waste or small quantity generator hazardous waste
are in compliance with 40 CFR part 257, "Criteria for
Classification of Solid Waste Disposal Facilities and
Practices."  This permit program was to be established by
November 8, 1987.  The EPA views this permit program as a
readily available resource for States to use in implementing
today's guidelines and judged States would be able to identify
active facilities as of this date.  For these reasons, the EPA
has defined a designated facility as an existing landfill that
received waste on or after November 8, 1987, or has additional
capacity which may be filled in the future.
     With regard to the suggested cutoff dates of 1965 to
1970, many States lack the information necessary to identify
all landfills that closed that long ago.
     Section ill of the CAA defines a new source as one
commencing construction on or after the date of proposal
(May 30, 1991) of the applicable standard.  Therefore, the
distinction between new and existing MSW landfills was not
determined as a part of this rulemaking, but was set at the
date of proposal, as mandated by the CAA.
     The focus of the rulemaking is control of the designated
pollutant, MSW landfill emissions, at new and existing MSW
landfills.  Any landfill subject to the emission guidelines
accepting waste or having capacity available for future waste
acceptance between November 8, 1987, and the proposal date
would have to exceed the regulatory cutoff before installation
of collection and control systems would be required.
     Even though the actual decline in the emission rate
varies from landfill to landfill, in general landfills closing

                             2-29

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  prior to 1987 emit at declining rates, while landfills closing
  after the 1987 cutoff date may warrant control.  However, as
  stated in the proposal preamble, the model and information
  presented in the proposal preamble and BID are appropriate for
  application to older landfills, and States are encouraged to
  use them to assess the emission potential of any closed
  landfills of concern under the emission guidelines.
       The EPA found that the majority of landfills are either
  part of a municipal system or else corporately owned.  There
           •
  are few independently owned and operated landfills.  If an
  individual landfill does not have adequate resources, a State
  may consider making a case-by-case showing for the landfill,
  or a group or class of landfills, that a less stringent
  emission guideline is warranted.  Under 40 CFR 60.25(f), a
  State may apply a less stringent standard based on
  unreasonable cost, physical impossibility, or other  factors
  specific to the landfill or class of landfills that  make
  application of a less stringent standard significantly more
  reasonable.  States may submit such case-by-case
  determinations to the EPA for review as part of the  submittal
  of their plan to implement the EG.
       Comment:  One commenter  (IV-L-1) recommended that all
  design and construction plans for new landfills, or  expansions
  of existing landfills, contain active landfill gas collection
  and control systems, regardless of the anticipated disposal
  capacity.
       Response;  The final rule requires only those landfills
  that exceed the emission rate cutoff of 50 Mg/yr to  install a
  collection and control system to control emissions of NMOC.
  The EPA encourages owners or operators of new  landfills or
  existing landfills that are in the process of  expanding to
  begin planning for collection and control systems  if they
  anticipate ever having a design capacity that  would  exceed
  2.5 million Mg or 2.5 million m3 and an emission rate of
  50 Mg/yr.  The EPA has included a design capacity  exemption of
  2.5 million Mg or 2.5 million m3 in the final  rule and

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   estimates that this will exempt approximately 90 percent of
   affected landfills from the recordkeeping and reporting
   requirements of the rule.  These landfills are excluded for
   reasons described in section 2.4.1.1.   The final rule focuses
   on control of larger landfills where there is the greatest
   emission reduction potential and reduces the regulatory burden
   on small entities.   The EPA will not require an owner or
   operator to include active landfill gas collection and control
   systems in their design plans if they do not anticipate
   exceeding the design capacity exemption and the 50 Mg/yr
   control applicability cutoff.  The MACT standard that must be
   promulgated in the future for municipal landfills will examine
   whether smaller landfills have significant hazardous air
   pollutant emissions.
   2.4.1  Exemptions from Control
        Comment;   One commenter (IV-D-8)  requested exemption from
   these regulations, based on the administrative and cost
   burdens,  for all industrial/municipal  solid waste disposal
   facilities where less than 15 percent  of waste is MSW.
        A second commenter (IV-D-6)  stressed that landfills that
   accept large amounts of MWC ash should be regulated under RCRA
   subtitle 0 rather than under the CAA,  and that landfills
   accepting only MSW should be regulated by the proposed
   standards.
        A third commenter (IV-D-27)  recommended that the
   regulation allow owners and operators  to demonstrate that some
   older portions of the landfill may be  virtually nonproductive
   and,  therefore,  not warrant the placement of collection wells.
   The commenter suggested that exclusion provisions similar to
   those established for asbestos deposition be crafted.
   Additionally,  the commenter proposed that gas generation rate
   calculations should not be required for areas excluded from
   the system since the rates could only  be determined from an
   active collection system.
        In addition,  the commenter (IV-D-27)  proposed that the
   provisions for exempting areas of asbestos deposition in the

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  guidelines be extended to the NSPS, noting that asbestos will
  continue to be disposed of in MSW landfills.  The commenter
  further noted that documentation of the deposition area may
  not be available, and warned that erroneous drilling through
  asbestos may occur if the owner is required to keep the
  excluded areas below 1 percent emission potential.  The
                                                   • %
  commenter recommended greater flexibility in excluding areas
  of asbestos deposition.
       Another commenter (IV-D-39), however, recommended the
            *
  elimination of the exclusion for areas of a landfill based on
  the presence of asbestos and nondegradable materials.  The
  commenter asserted that these exclusions will lead to unequal
  enforcement of the regulations and not provide the level of
  environmental protection that the EPA seeks.  The commenter
  argued that an operator hypothetically could, through the
  acceptance of very small quantities of asbestos, landfill the
  waste so that most of the landfill's area is excluded from the
  requirements pertaining to the installation of gas recovery
  wells.  Also, since many landfills have disposed of
  nondegradable material as the landfilling operations
  progressed and few have records of disposal location,
  regulatory enforcement of this section would be difficult.
       Response:  While it is true that many MSW landfills have
  accepted non-MSW  in some quantity, the regulations do not
  exempt these landfills from the standard because the LFG
  emissions depend  on the organic material in the waste, not on
  the origin of the waste.  The emissions of concern, LFG
  emissions, result primarily from degradation of organic
  material, which may result from deposition and degradation of
  MSW,  industrial solid waste, commercial solid waste,
  conditionally exempt small quantity generator waste or
  nonhazardous sludge.  All of these wastes may contribute to
  LFG emissions.  Therefore, the MSW landfill definition must
  include all of these constituents, and does not include a
  percentage MSW cutoff.


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        The final regulations are structured to require
   collection and control based on NMOC emission potential,  and
   the emission rate calculations are based on the amount and age
   of the waste, regardless of its origin.   As provided in
   S 60.754 of the NSPS,  the emission rate  calculations include
   summing the individual emission rates from each yearly submass
                                                   • *
   of waste material.  Areas may be excluded from the  collection
   system only through three mechanisms: documentation must be
   provided for nonproductivity due to age,  nonproductivity due
   to nondegradable nature (e.g.,  cement, MWC ash),  and the
   presence of asbestos.
        Older "nonproductive" organic waste will likely be
   emitting at some low rate, and the regulation would exempt
   such an area from control provided that  its calculated
   emission potential can be shown to be less than 1 percent of
   the overall emission potential of the landfill.  If the age
   and mass of an older area is known,  the  current emission rate
   for that submass can be calculated and compared to  the overall
   emission rate.  Since  emissions from each yearly submass
   decline with age, the  actual ages of these submasses will
   govern how many of these submasses may be excluded  from
   control before the 1-percent limit is reached.  The data and
   calculations that provide the basis for  excluding such areas
   must be documented and provided to the Administrator upon
   request.
        Landfills receiving wastes other than,  or in addition to,
   MSW may,  however, be able to demonstrate an emission rate
   below the regulatory level,  via the provisions for  the
   exclusion of nondegradable areas of the  landfill.   These
   provisions would likely exempt dedicated landfills  receiving
   only demolition waste  or MWC ash because such landfills may
   not emit above the emission rate cutoff.   Nondegradable waste,
   such as cement or MWC  ash, is exempted because it is not
   contributing to the LFG emission rate, and these provisions
   specify that the mass  of nondegradable refuse is not to be
   included when estimating emissions.   In  the final NSPS, the

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  1-percent condition is not required of asbestos or
  nondegradable material, provided that documentation is
  provided on the nature, date of deposition, location, and
  amount of material deposited.  This approach is preferable to
  excluding landfills that accept a certain percent of MWC ash
  from the NSPS and EG because landfills that accept a mixture
                                                   • %
  of MWC ash and MSW may still emit significant amounts of
  landfill gas from the MSW and may warrant control.  Regulating
  such landfills only under RCRA instead of the NSPS and EG
  would not necessarily address the air pollution concerns.
       The intent of the exclusion for asbestos was to avoid a
  known, documented hazard, rather than to permit circumvention
  of the regulations based on either a hunch about the presence
  of asbestos or poor management practices.  The EPA will allow
  exclusions based on asbestos deposition only for those cases
  where such deposition is managed and fully documented.
       As discussed in the previous response, a State may make a
  case-by-case showing for the landfill, or a group or class of
  landfills, such as a landfill where a very small percent of
  the waste is MSW, that a less stringent emission guideline is
  warranted if the criteria in 40 CFR 60.25(f) are met.
       Comment;  One commenter  (IV-D-54) stated that alternative
  standards should be proposed for facilities in cold regions
  that have reduced their LFG emissions by using designs that
  freeze the waste.  The commenter suggested that if a
  temperature monitoring system can assure that the waste is
  stored at a temperature below freezing, then a gas collection
  and control system should not be required.
       Response;  The regulation provides for a situation such
  as this.  A low NMOC emission rate can be verified through
  sampling and analysis using Method 25C.  If the NMOC emission
  rate is below 50 Mg/yr, installation of a gas collection and
  control system is not required.  However, if the NMOC
  concentration is high enough to result in a calculated NMOC
  emission rate above the emission rate cutoff, the landfill
  would warrant control under these regulations.  For existing

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   The design capacity exemption was re-evaluated in the interim
   between proposal and promulgation,  and has been revised to
   2.5 million Mg or 2.5 million m3.
        The proposed design capacity cutoff of 100,000 Mg of
   waste was chosen so that no landfill would be exempted and
   have actual emissions above the emission rate cutpff.  Several
   comments were submitted requesting an increase in the
   exemption level.  An increase would relieve additional owners
   and operators of small landfills from the emission estimation
   and control requirements.  In addition to the comments,
   changes to the data base and the emission modeling values
   prompted the design capacity exemption level reevaluation.
   The new design capacity analysis evaluated a range of options
   from 500,000 Mg to 4.0 million Mg of waste.   Two important
   considerations in the selection are the number of landfills
   exempted and the amount of potential NMOC emission reduction
   lost from the exempted landfills.
        The 2.5 million Mg exemption level would exempt
   90 percent of the existing landfills while only losing
   15 percent of the total NMOC emission reduction.   Therefore,
   2.5 million Mg was chosen since losing 15 percent of the
   emission reduction is a reasonable tradeoff to relieve as many
   small business and municipalities as possible from the
   regulatory requirements while still maintaining significant
   national emission reduction.   The 2.5 million Mg exemption
   level excludes those landfills,  both public and private, would
   be at least able to afford the costs of collection and control
   systems.   The lowest value considered,  500,000 Mg,  only allows
   slightly more than 1 percent of the total emission reduction
   potential to go unregulated;  however,  only 62 percent of the
   landfills are exempted.   Under this option,  a large proportion
   of landfills would be required to perform annual  emission
   calculations and would experience significant recordkeeping
   and reporting burdens,  even though  they would never reach
   50 Mg/yr and would never be required to install controls.
   The highest capacity value considered,  4.0 million Mg,  would

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  allow over 20 percent of the potential emission reduction to
  go unregulated.
       Since some landfills record waste by volume and have
  their design capacities calculated in volume, EPA also
  established an equivalent design capacity exemption of
  2.5 million m3 of waste.  The density of landfilled solid
  waste varies from landfill to landfill depending on several
  factors, including the compaction practices.  Any landfill
  that reports waste by volume and wishes to establish a mass
  design capacity must document the basis for their density
  calculation.
       All MSW landfills above the design capacity exemption
  level  (maximum design capacity) must periodically calculate
  their annual NMOC emission rate to determine  if controls are
  warranted.  See responses in section 2.15, "Reporting and
  Recordkeeping", for consideration of the resulting paperwork
  burden.  The EPA remains convinced that control of landfills
  smaller than the design capacity exemption is a reasonable
  tradeoff to focus effort on those landfills with the highest
  potential for emission reductions.  However,  States have the
  freedom to require additional monitoring, LFG collection, or
  control to address State concerns.  At the time MACT standards
  are developed for landfills under section 112 of the CAA, EPA
  will assess the HAP emission potential from landfills and
  decide whether smaller landfills warrant control for HAP
  emissions.
       2.4.1.2  Co-combustion of Landfill Gas
       Comment;  One commenter  (IV-D-16) suggested that the
  proposed regulations do not account for the possibility that
  some enclosed combustors could be used for combusting fuels
  other than LFG.  In particular, the commenter was concerned
  about MWC's subject to the NSPS for MWC's that also combust
  LFG.  The commenter recommended that the standards be changed
  to exclude facilities which are already regulated by other
  standards of performance and/or emissions guidelines
  promulgated under the CAA from the requirements of these

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   landfills,  a State could establish an alterative emission rate
   cutoff based on the criteria provided in 40 CFR 60.24(f).
        Comment;   After the notice of data availability
   (58 FR 33790,  June 21,  1993), one commenter (IV-L-5)  inquired
   as to what  types of materials other than nonprocessible
   materials (white goods), could be excluded from consideration
   as MSW for  modelling air emissions for use in determining
   whether collection and  control systems should be installed.
        Response;  The EPA did not request comment on materials
   exempted from  control in the notice of data availability.  The
   EPA assumes that by the term nonprocessible materials (white
   goods)  the  commenter is referring to either nondegradable
   materials or nonproductive areas.  Under S 60.759(a)(3)(i) of
   the final rule, segregated areas of asbestos or nondegradable
   materials may  be excluded from control if documentation is
   kept on the nature, date of deposition, amount and, location
   of the waste.   Nondegradable waste, such as demolition waste
   or MWC ash,  is exempted because it does not contribute to LFG
   emissions.   Under S 60.759(a)(3)(ii)  of the final rule,  older,
   nonproductive  areas of  the landfill may be excluded from
   control,  if the total of all excluded areas contributes less
   than 1 percent of the total amount of emissions from the
   landfill and they are documented.
        2.4.1.1  Design Capacity Exemption
        Comment:   Several  commenters (listed below)  discussed the
   proposed design capacity exemption of 100,000 Mg.  One
   commenter (IV-D-7)  contended that because of the current costs
   associated  with the siting, permitting, and development of
   landfills,  no  additional MSW landfills having design
   capacities  less than 100,000 Mg will be built.  The commenter
   said that the  exemption level should be raised to 1.0 million
   Mg because  the calculation method used in the regulation
   overestimates  NMOC emissions.  Two commenters (IV-D-20,
   IV-D-54), suggested an  exemption level of 550,000 Mg because
   they reasoned  that landfills smaller than this would not emit
   more than 150  Mg/yr anyway. The commenters contended that the

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  lower exemption level would unnecessarily increase the
  regulatory burden of the standard, and will burden small
  landfills and State regulatory agencies.  Another commenter
  (IV-D-51) also argued that the proposed design capacity
  exemption level was too low.
       One industry commenter (IV-D-27) approved of a design
                                                   • %
  capacity exemption level of 100,000 Mg, but also noted that
  there would still remain considerable burden for small
  landfills that would be exempted at Tier 1, noting that about
  35 percent of Tier l MSW landfills are never required to
  install controls.  The commenter applauded the conservative
  basis for review of MSW landfills to identify those warranting
  gas control and praised EPA's effort to obtain information
  from the regulated community.  The commenter recommended,
  however, that all MSW landfills be evaluated for NMOC emission
  rates, instead of only those above the design capacity
  exemption level.
       Another commenter (IV-D-36) agreed, suggesting that  if
  LFG is an environmental concern, then all landfills,
  regardless of size, should be regulated, or at least monitored
  to determine if control is necessary.
       Another commenter (IV-D-39) asserted that the 100,000 Mg
  cutoff is not based on technical justification or cost/benefit
  analyses using NMOC emission data.  The commenter stated  that
  small landfills that are poorly designed and operated may have
  emission levels that exceed levels found at large, properly
  designed and operated landfills.  The commenter  asserted  that
  all owners or operators should be required to report emission
  levels that have been certified by an appropriate
  professional, such as a professional engineer.
       Response:  These regulations, including the design
  capacity exemption level, are based on NMOC emission
  potential.  After BDT was determined, the design capacity
  exemption was selected to reduce the paperwork burden on
  landfills that typically would not have a calculated NMOC
  emission rate large enough that controls would be required.

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   regulations.  The commenter also suggested the regulations
   should provide a different emission limit for facilities
   burning LFG along with other fuels.  The commenter requested
   that the compliance test method be appropriate for use with
   LFG and LFG mixed with other fuels, and noted that
   co-combustion may affect the test methods provided in these
   regulations.
        Response:  The EPA does not consider it difficult to
   demonstrate either a 98-percent reduction in NMOC or a 20 ppmv
   TOC concentration when LFG is combusted in an MWC.  Because
   the format of the MWC NSPS is a set of emission limits for
   individual pollutants, while the format for this NSPS is a
   performance standard for total NMOC,  the performance tests in
   the NSPS for MWC's differ from the performance test provided
   in these regulations.  When only LFG is fired in a combustor,
   it will be subject only to the control requirements of this
   NSPS and EG.
        In addressing the commenter's concern, the EPA looked for
   ways to relieve undue regulatory overlap while still ensuring
   that BDT is not compromised.  The final regulation clarifies
   that alternative methods of compliance demonstration can be
   used if approved by the Administrator.  For example, for a
   situation when both LFG and refuse is combusted in an MWC
   simultaneously,  a design analysis and any other information
   demonstrating that the standards can be continuously achieved
   must be submitted to and approved by the Administrator.
        In the development of the Hazardous Organics NESHAP (HON)
   and previous NSPS for process vents that may be controlled by
   routing organic-containing gases to boilers,  the EPA
   determined that a performance test would not be required for
   boilers or process heaters with a design heat input capacity
   of 44 MW or greater.   Analysis shows that when vent streams
   are introduced into the flame zone of these boilers and
   process heaters,  over 98 percent reduction or an outlet
   concentration of 20 ppmv is achieved.   Therefore, a
   performance test is not necessary.   If,  however,  the gas

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  stream is combusted in a boiler or process heater with a
  design heat input capacity of less than 44 MW, a performance
  test to demonstrate 98 percent NMOC reduction or 20 ppmv is
  still required.  The final NSPS has been amended to
  incorporate these provisions.
  2.4.2  Selection of the Tier Default Values
                                                   • %
       Comment;  Three commenters  (IV-D-4, IV-D-7, IV-D-26 and
  IV-F-6) contended that the NMOC default concentration of
  8,000 ppmv is overly conservative and recommended alternative
  concentrations as more representative.  One of the commenters
  (IV-D-7) referred to tests conducted in humid climates
  yielding NMOC concentrations of 200 to 500 ppmv.
       Another commenter (IV-D-39) asserted that the default
  NMOC concentration value of 8,000 ppmv as hexane is not
  justified in the proposal BID, and questioned how it was
  derived.  The commenter stated that this value should be re-
  examined and that the analysis should address differences in
  NMOC concentration based on the waste types received at the
  landfills.
       Another commenter (IV-D-28) alleged that there is no
  established technical basis for the refuse decay rate value
  (k) of 0.02/yr or the refuse methane generation potential  (Lo)
  of  230 m3/Mg and, therefore, these values should be excluded
  from the regulation until adequate technical justification
  exists.  A second commenter  (IV-F-6) stated that the k value
  of  0.02 is too conservative and overstates gas production
  rate.  A third commenter  (IV-D-17) listed the range of
  variation for these two defaults and stated that the EPA
  should fund contracts to study the variability of the LFG
  generation constant, k, and the methane generation potential,
  Lo, to see if the variations can be reduced.  Another
  commenter  (IV-D-26) argued that the default k and Lo values
  overpredict production of gas, thereby requiring collection
  when "real" emissions levels may be very low.  The commenter
  asserted that the default Lo is the most critical value and


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   that the proposed regulation does not allow a calculated value
   to be substituted in the estimation.
        Response;   The default values for use in the tier
   calculations were not chosen to be average values.   Owners or
   operators wanting average values for  use in system design or
   inventory should use the values published in the latest
   version of EPA's AP-42 document.  Selection of the default
   NMOC concentration provided in the tier calculation was not
   based on test data alone.  Rather,  it was chosen in concert
   with the defaults for the methane generation potential (Lo)
   and the refuse decay rate constant (k).  The objective of the
   defaults selection process was to obtain a balance between
   lost emission reduction potential and cost of performing the
   field tests in Tiers 2 and 3 on a nationwide level as
   described in the memorandum entitled  "Rationale for Selecting
   Tier 1 Default Values" (Docket No.  A-88-09,  Item No. II-B-33).
   More specifically,  the default values were selected such that
   there is low potential that they will significantly
   underestimate emissions for individual landfills (resulting in
   less emission control); yet the defaults will not overestimate
   emissions by such an extent that a large number of landfills
   would be over 50 Mg/yr according to Tier 1 and would undergo
   the expense of Tiers 2 and 3 and show that they are actually
   below 50 Mg/yr.
        It should be noted that the default NMOC concentration
   reflects some existing landfills that may have a history of
   codisposal of hazardous waste.   Data  received from codisposal
   landfills indicates that the NMOC concentrations from
   codisposal sites are typically higher than NMOC concentrations
   from nonhazardous MSW landfills.  However, because of RCRA
   regulations preventing disposal of hazardous waste in MSW
   landfills,  only NMOC concentrations from landfills that never
   accepted hazardous waste were used to characterize landfills
   opening after 1987.   The NMOC concentrations from landfills
   that accepted hazardous waste as well as landfills that never
   accepted hazardous waste were both used to characterize

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  landfills opening through 1987.  The memorandum "Methodology
  used to Revise the Model Inputs in the Municipal Solid Waste
  Landfills Input Data Bases  (Revised)" (Docket No. A-88-09,
  Item No. IV-M-4) discusses  the rationale used to calculate and
  select values for k, Lo/ and C^MOC*  As discussed in later
  comments in this section, the default values have been revised
                                                   ' %
  since proposal.
       For data to be used to obtain default k values, the
  following had to be available:  test year, year landfill
           •
  opened, year landfill closed (if closed), amount of
  refuse-in-place in the test year, refuse acceptance rate, and
  the actual methane flow rate.  For data to be used to obtain
  default NMOC concentrations, the following had to be
  available:  the total NMOC  concentration and associated units
  (e.g., ppmv as hexane, ppmv as methane), the methane
  concentration and the CO2 concentration  (to correct for air
  infiltration since landfill gas is primarily methane and  CX>2) ,
  and the test method used.   Also, the test method used had to
  be comparable to EPA Method 25C.
       Comment;  One commenter (IV-L-2) contended that the  k,
  Lo, and CNMOC values will vary based on more than just
  geographic location, which  the commenter stated was a
  surrogate for precipitation.  Other factors the commenter
  (IV-L-2) mentioned that could influence the values included:
  the categories and relative quantities of waste produced
  according to the local economic conditions and emphasis,  the
  amount and types of  materials diverted from the waste stream
  by recycling, and other physical characteristics of the region
  where the subject landfill  is located and their  influence on
  the design of the landfill. The commenter  (IV-L-2) noted that
  all or most  of the landfills added to the database are from
  arid regions.
       Response;  The commenter is correct in noting that there
  are many factors that influence k, Lo, and CNMQC values at
  each landfill.  The purpose of the MSW landfills data base  is
  to reasonably represent the variability  among  landfills  in the

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   U.S.   While the EPA agrees that its approach cannot accurately
   estimate emissions at a given landfill without additional
   site-specific information, the EPA supports the methodology
   for emissions estimates on a nationwide basis.   All of the
   randomly assigned factors were determined from data on
   existing landfills, and available literature was ^reviewed to
   establish reasonableness criteria for using this information
   in the model.
        While it would be infeasible to factor every variable
            •
   into the emissions estimation model, the model does account
   for the percentage of landfills in arid versus moist regions.
   This was a way to factor the influence of moisture into the
   analysis.  In order to factor other influences into the
   analysis, a large amount of resources and time would need to
   be spent and the outcome is questionable.   The data on
   precipitation and location,  however, were readily available.
   For further information on arid versus moist k and Lo values
   used in the landfills data base,  see section 6.0 of the
   memorandum "Methodology Used to Revise the Model Inputs in the
   Municipal Solid Waste Landfills Input Data Bases (Revised),"
   April 28, 1993 (Docket No. A-88-09,  Item No.  IV-M-4).
        Comment;  One commenter (IV-L-4)  alleged that there is no
   established technical basis for the "revised" k value of
   0.03  yr-1 or the Lo value of 140 m3/Mg.   The commenter
   (IV-L-4)  cited as reasons:  the enactment of Federal final
   cover standards which should cause landfills to be "extra
   arid," resulting in a decreased k,  and the enactment of State
   recycling programs, which remove paper and landscaping waste,
   resulting in reduced Lo values.   The commenter (IV-L-4)
   recommended not using the revised k and Lo values in the rule,
   but offered no alternative values or methodology.
        Response:   The k and Lo values are used as input
   parameters in the model equation for estimating NMOC emissions
   from each landfill in the input data bases.   The revised k and
   L0 values were derived from known landfill-specific data
   obtained from SCAQMD test reports,  section 114  letter

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  responses, ORD studies, and landfill gas to energy data
  updated by SWANA.  A description of the methodology used to
  calculate new k and Lo values can be found in the memorandum
  entitled "Methodology Used to Revise the Model Inputs in the
  Municipal Solid Waste Landfills Input Data Base (Revised),"
  April 28, 1993, (Docket No. A-88-09, Item No. IV-M-4).
       The k value of 0.02 yr"1 and Lo value of 230 m3/Mg were
  the proposed default values for use in Tier 1 of the rule
  where an owner or operator will estimate the annual NMOC
           •
  generation for a landfill.  The k and Lo values of 0.03 yr'1
  and 140 m3/Mg are the average k and Lo values in the input
  data bases and do not correspond to the default values to be
  applied in the rule.  Default values were not chosen to be
  average values.  Owners or operators wanting average values
  for use in system design or inventory should use the most
  current values published in AP-42.
       Default values for the tier calculations are determined
  by an optimization analysis between estimated nationwide costs
  of performing the tier analyses and total nationwide emissions
  reduction of the rule.  Defaults that result in greatly
  overestimated emissions would result in more landfills
  exceeding the 50 Mg/yr applicability level under Tier 1.  An
  increased number of landfills would then undergo the expense
  of Tier 2 and 3 testing.  If Tier 1 greatly overestimated
  emissions, many of the landfills that did Tier 2 and 3 testing
  would find they emit below 50 Mg/yr and are not required to
  apply controls; thus, they would incur high test costs and no
  emission reduction benefits.  On the other hand, if the
  defaults underestimate emissions, landfills that actually have
  emissions over 50 Mg/yr would escape control.  This would
  result in less emission reduction than intended.  The default
  values selected were considered to achieve the best balance
  between resulting in control of those landfills that emit over
  50 Mg/yr without resulting in overly burdensome national costs
  for tier analysis.
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        For the final rule, the default values were revised to
   k = 0.05 yr"1; L0 = 170 m3/Mg; CNJJQC = 4,000 ppmv as hexane.
   More information on this subject may be found in the
   memorandum "Documentation of Small-Size Exemption Cutoff Level
   and Tier 1 Default Values (Revised)," April 27, 1995 (Docket
   No. A-88-09, Item No.  IV-B-10).
        The average k and Lo values of 0.03 yr"1 and 140 m3/Mg in
   the input data bases were representative of currently existing
   landfills..  As discussed in the methodology memorandum listed
   above,  (Docket No. A-88-09,  Item No. IV-M-4), the gas
   generation from arid versus moist landfills was considered in
   the development of the k and Lo values for each landfill in
   the input data bases.   Also, the rule allows site-specific k
   values  to be determined for each landfill if the landfill
   chooses to perform a Tier 3 analysis.
        The primary criteria effecting Lo of a landfill is the
   cellulose content of the refuse.  State recycling programs
   that remove paper and landscaping waste may effect Lo of
   landfills; however, the extent to which these programs will
   effect  L0 cannot be accurately quantified and currently
   available data must be used.  However, under
   § 60.759(a)(3)(i)  of the final rule, segregated areas of
   asbestos or nondegradable materials may be excluded from
   control if documentation is kept on the nature, date of
   deposition,  amount, and location of the waste.
        Comment;   One commenter (IV-L-7) supported the use of the
   maximum Lo at each landfill, instead of the average in
   calculating potential  landfill emissions.  Another commenter
   (IV-L-2)  objected to limiting the maximum Lo for an individual
   landfill that could be greater than 7,000 ft3 methane/Mg of
   refuse.  The commenter (IV-L-2)  also expressed concern because
   the data used to determine the range of possible Lo values was
   compiled from one source.  The commenter (IV-L-7) who
   supported the use of the maximum Lo stated that the net result
   of the  changes to the  methodology for calculating generation
   potential is a decrease in the total potential gas emissions

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  nationwide and results in fewer landfills requiring controls.
  The commenter (IV-L-7) contended that the same was true for
  the results of the revised inputs to the concentration of
  NMOC.  The commenter  (IV-L-7) stated that this was a departure
  from the traditional  EPA practice of assuming a worst case
  scenario in protecting the environment.
                                                  • *
       Response:  The revisions to the methodology  for
  determining L0 values and CNJJOC values used in the input data
  bases provide estimates of methane and NMOC emissions that are
  lower than the proposal estimates.  The revisions are based on
  additional information that was obtained since proposal, and
  the EPA believes that the revised estimates more  accurately
  represent nationwide  landfill emissions.
       The EPA used the Lo range of 2,000 to 7,000  ft3
  methane/Mg refuse to  define the minimum and maximum Lo values
  that can be assigned  to any landfill in the input data bases.
  This Lo range, taken  from "Methane Gas in Landfills:
  Liability or Asset?"  presented at the Fourth National Congress
  of the Waste Management Technology and Resource and Energy
  Recovery, was chosen  because it falls within the  total range
  of L0 values reported in the numerous references  reviewed by
  the EPA.  Therefore,  the commenter is incorrect in suggesting
  that the range of Lo  values came from one source.
       Based on a literature review and available data, the EPA
  has determined that an L0 range of 2,000 to 7,000 ft3
  methane/Mg refuse is  appropriate.  The literature review
  revealed that 7,000 is the upper end of the range that is
  typical, and values exceeding this would be unlikely due to
  the amount of methane producing material that could be
  realistically placed  in a landfill and eventually converted to
  methane.
       Comment:  One commenter  (IV-L-3) contended that an Lo of
  1,700 to 3,500 ft3 methane/Mg wet waste is more appropriate
  than the higher L0 of 4,913 ft3 methane/Mg proposed by the
  EPA.  The commenter noted a 1991 paper by Augenstein and Pacey
  that presents an Lo of 1 to 2 ft3 methane/dry pound of waste.

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   The commenter stated that assuming a waste moisture of 20 to
   25 percent,  translates to an Lo value of 1,700 to 3,500 ft3
   methane/Mg wet waste.
        The commenter (IV-L-3)  mentioned work of Augenstein
   (1976a,b), and Chynoweth and Legrand (1991)  that have shown an
   L0 value on the order of 3 ft3 methane/pound of dry volatile
   solids under lab conditions.  The commenter (IV-L-3) contended
   that with waste at 20 to 25 percent moisture, 25 percent ash,
   and the balance volatile organics,  the upper limit of Lo can
   be calculated based on these lab results to be about 3,500 ft3
   methane/Mg.
        The commenter (IV-L-3)  stated that dry landfill methane
   fermentation conditions are more typical and methane
   conversion will consequently be less than the potential
   maximum.  The commenter (IV-L-3)  stated that this is supported
   by the findings of apparently unaltered material even after
   many decades of burial,  in several articles by Rathje.  In
   addition,  the commenter (IV-L-3)  asserted that shallower
   landfills as well as those with more porous covers may be
   partly aerobic, reducing methane yield.
        The commenter (IV-L-3)  acknowledged that there are
   numerous projections and calculations by the EPA and their
   contractors  of methane yields much higher than 3,500 ft3
   roethane/Mg.   However, the commenter (IV-L-3)  contended that
   these higher yield projections are stoichiometric calculations
   rather than  laboratory results with representative solid
   waste.  The  commenter (IV-L-3)  stated that actual biological
   methane production will be substantially lower than
   stoichiometric estimates because much organic material is
   undecomposable and much of the degradable fraction is shielded
   by lignin.  The commenter (IV-L-3)  stated that similar points
   have been made by Professor Morton Barlaz (Barlaz 1991).
        Response:   Numerous references were reviewed that
   identified values for Lo.   These items are summarized in the
   memorandum "Methodology Used to Revise the Model Inputs in the
   Municipal  Solid Waste Landfills Input Data Bases (Revised),"

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  April 28, 1993,  (Docket No. A-88-09, Item No. IV-M-4).  It was
  determined that L0 values are highly variable and difficult to
  quantify on a landfill-specific basis.
       The range of Lo values recommended by the commenter
  (1,700 to 3,500 ft3 methane/Kg) falls mostly within the range
  used by EPA (2,000 to 7,000).  Also, applying the range of L0
                                                   • %
  values to the actual emissions data from the 44  landfills
  presented in the memorandum indicates that 25 percent of the
  landfills would not have a solvable k value at an Lo of
           •
  3,500 ft3 methane/Mg, indicating that actual L0  values may be
  greater that 3,500.  This indicates that the larger range of
  2,000 to 7,000 ft3 methane/Mg would be more appropriate.
       Comment;  One commenter (IV-L-2) requested  clarification
  on the methodology used to calculate k values using the Lo
  values, and contended that this process appears  to produce k
  and Lo values that are proportional to each other.
       Another commenter  (IV-L-3) noted that the use of lower Lo
  values implies higher k values.  The commenter acknowledged
  that k is back calculated from Lo.  The commenter stated that
  k and Lo are approximately reciprocal and that the effect of
  higher k values and lower Lo values would shorten the
  projected term of methane generation, as well as the
  cumulative NMOC emission over the  long term.
       Response:  The k and Lo values determined for each
  landfill in the data base are based on measured  landfill gas
  emissions and waste acceptance rate data for existing
  landfills.  Based on this data, for a given Lo value, a k
  value was calculated using the model equation.   This  gives a k
  and L0 value that, when the model  equation is used, yields a
  gas generation rate equivalent to  the measured flow rate.
  While these values are related exponentially due to the model
  equation, they are not directly proportional or  linear to one
  another.  See "Methodology Used to Revise the Model Inputs in
  the Municipal Solid Waste Landfills Input Data Bases
   (Revised),11 April 28, 1993,  (Docket No. A-88-09, Item
  No. IV-M-4) for more information on this topic.

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        Comment;   One commenter (IV-L-2)  suggested that the upper
   limit of the 80th percentile confidence interval on the mean,
   and not the median, be chosen for the expected k and Lo
   values.
        Response:  In the period between proposal and
   promulgation,  the EPA decided that determining a site-specific
   potential Lo range for each of the 44 landfills and then using
   the median Lo for each landfill would be more representative
   of reasonable gas generation potential than using the 20th and
            *
   80th percentiles equally with the median value, as was done in
   the proposal analysis.  Using a median L0 value reduces the
   potential error in estimating emissions from individual
   landfills using the model equation.   This eliminates the
   possibility of assigning high Lo values to landfills that may
   actually have  low values, and vice versa.  In order to
   calculate the  upper limit of the 80th percentile confidence
   interval on the mean,  a distribution of Lo values is
   necessary.   The Lo value will vary depending upon the
   characteristics of the refuse disposed at individual
   landfills.
        The data  available only provided a range of Lo values
   that are most  likely to exist at landfills.   A distribution of
   the range of L0 values at landfills in the U.S. was
   unavailable and would require a great deal of additional
   resources and  time to obtain.
        Comment;   One commenter (IV-L-5)  requested clarification
   on the input parameters for estimating air emissions from
   existing MSW landfills using the model "Landfill Air Emissions
   Estimation Model,  Version l.l" obtained from the EPA's CTC.
   The commenter  (IV-L-5)  inquired whether the CTC's version 1.1
   model is identical to the model used to develop the data in
   the EXISCLOS data base.
        Response;   The CTC's Landfill Air Emissions Estimation
   Model (version 2.0, which is the most recent version)  uses the
   same equation  that is used to derive the landfill gas
   generation rate for the final rule.   Version 2.0 of the CTC

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  model has been revised to include the default values for k,
  L0, and CNJJOC used in tne final rule.  A copy of the air
  emissions estimation model  (version 2.0) is available from the
  Control Technology Center.
  2.4.3  Removal of Controls
       Comment;  One industry commenter (IV-D-27) disapproved of
  the proposed 3-step removal criteria for control systems.  The
  commenter recommended the use of a single criteria for the
  removal of controls:  a calculated NMOC emission rate less
           •
  than the stringency level of 150 Mg/yr demonstrated two times
  within a 2-year period, not closer together than 12-months.
  Other commenters  (IV-D-39,  IV-D-48, IV-F-6) disapproved of the
  15-year time limit for removal of collection and control
  systems.  One commenter  (IV-F-6) recommended that removal of
  controls be allowed as soon as the emission level falls below
  the designated rate.
       One commenter (IV-D-48) disapproved of the 15-year time
  limit for operation of the gas collection and control system
  at Superfund sites.  The commenter asserted that MSW Superfund
  sites have often been closed for 20 to 30 years before site
  investigation begins and a  need for emission controls is
  discovered.  The commenter  contended that because of the
  relatively old age of Superfund sites, 15 years of gas
  collection would not give the marginal benefit to substantiate
  the operational costs.  The commenter also argued that the
  operation and maintenance costs generally exceed capital
  costs, especially at Superfund sites, because the Btu content
  of the gas is often insufficient without the aid of costly
  auxiliary fuels.  The commenter recommended that the removal
  of controls be determined on a site-by-site basis.
       Another commenter  (IV-D-39) asserted that data justifying
  the 15-year minimum operation time of a collection and control
  system is not provided and  that the 15-year time period
  appears to be based on a perceived useful life for the LFG
  equipment.  The commenter contended that their experience
  indicates that the useful life of gas collection equipment

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   should be based on site specific conditions and attainment of
   the emission limitations.   The commenter recommended that the
   proposed regulation be modified so that adjustments can be
   made to the gas collection system based on site-specific
   conditions, including cycling the system's operation,  or
   closing the system down prior to 15 years of operation, as
   long as the facility does  not exceed the "performance
   standard" (i.e.,  the regulatory cutoff).
        Another commenter (IV-D-32),  however,  disagreed with the
   proposed provisions for the removal of controls after as few
   as 15 years of operation.   The commenter supported a 30-year
   period instead, because the 15-year period was inconsistent
   with their State's post closure maintenance period for
   landfills.
        Response:  The 3-step removal criteria were selected to
   assure that all necessary  requirements are met before
   collection equipment is removed.   First,  the landfill must no
   longer be accepting waste.  This is necessary because landfill
   emissions continue to rise until after closure when waste is
   no longer being accepted.   Second,  testing in three successive
   periods must demonstrate that NMOC emissions are below the
   stringency level  of 50 Mg  per year.   This will require testing
   at different times of the  year,  giving a more realistic
   representation of the NMOC emission rate.   Moreover, testing
   LFG samples taken directly from the collection system is
   relatively inexpensive. Two testing periods would not as
   clearly describe  the NMOC  emission rate.   Third,  the
   collection and control system must have been in operation a
   minimum of 15 years.  The  15-year control period was selected
   based on the expected equipment life of the major system
   components.  It was determined that once the capital costs
   were paid and the emission rate fell below the regulatory
   emission rate cutoff, the  cost of reducing emissions would be
   significantly lower relative to the cost for controlling
   emissions including capital costs.   The SWANA submitted a
   survey of LFG collection systems (Docket No.  A-88-09,  Items

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  No. IV-G-Ol, IV-G-03), indicating that equipment replacement
  varied from 5 to 30 years, with vertical well replacement
  ranging from 10 to 20 years, and a 30-year life span for
  overall recovery systems.  Therefore, the EPA continues to
  consider the 15-year control period reasonable, given the
  additional emission reduction achieved for basic ^operating
  costs only.
       Superfund sites, however, are typically not actively
  receiving, waste.  To be subject to either the NSPS or the EG,
  a Superfund site would have to have accepted MSW since
  November 8, 1987 and emit above the emission rate cutoff.  Any
  landfill accepting waste since November 8, 1987, that
  continues to generate NMOC at 50 Mg/yr or greater will require
  a gas collection system under these regulations.  In cases
  where a gas collection system is required under these
  regulations, emission rates are such that the marginal benefit
  of gas collection for 15 years would be similar to younger,
  closed landfills requiring gas collection.  However, special
  situations at any site, Superfund or not, can be given special
  attention by the State in which the landfill is located.
       Any State may require 30 years of gas collection instead
  of 15 years, independent of these regulations.  The
  post-closure maintenance period mentioned by the commenter  is
  a RCRA provision and the basis for the control period was
  determined under a separate program.  It should be noted that
  MSW landfills are subject to any applicable requirements
  contained in rules developed under RCRA as well as the
  landfills NSPS and EG developed under the CAA.
  2.5  SELECTION OF THE POLLUTANT TO BE REGULATED
       Comment;  Two commenters  (IV-D-3, IV-D-6) argued that
  NMOC should not be classified as a surrogate for MSW landfill
  emissions because of  insufficient data in characterizing NMOC
   (IV-D-6) and because NMOC should only be considered as a
  substitute for MSW landfill emissions and not as a surrogate
   (IV-D-3).


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        Response;   The pollutant to be regulated,  MSW landfill
   emissions,  or LFG,  is composed of methane,  CO2, and NMOC.   The
   EPA selected NMOC as a surrogate for determination of control
   because NMOC includes those LFG constituents, of most concern.
   The nature  of the individual compounds commonly found in LFG
   and the health concerns they present are discussed in
   chapter 2 of the proposal BIO.  By controlling NMOC emissions,
   the non-NMOC constituents in LFG would also be controlled.   By
   basing control on NMOC emission rates, the  EPA is controlling
            •
   the subset  of landfills having MSW landfill emissions of
   greater concern.  The EPA, therefore, considers the use of
   NMOC as a surrogate for MSW landfill emissions to be effective
   and appropriate.
        Comment;  Four commenters (IV-D-19, IV-D-27, IV-D-29,
   IV-D-33)  addressed the pros and cons of methane as the
   designated  pollutant.   One commenter (IV-D-19)  stated that
   methane should be the surrogate for LFG because control of
   methane would likely result in the control  of NMOC as well.
   In addition,  methane is easier than NMOC to test and monitor.
   Another commenter (IV-D-27)  asserted that NMOC also
   contributes to ozone nonattainment and the  greenhouse effect.
   The commenter suggested performing a complete evaluation of
   ongoing methane studies, such as those being done by AEERL,
   WCRP,  and IGBP,  prior to subjecting MSW landfills to any
   additional  requirements.
        An environmental group (IV-D-33) recommended that a
   separate standard be developed for methane.  One commenter
   (IV-D-27) noted that some of the arguments  made in the
   preamble for not regulating methane could also be used as
   reasons not to regulate NMOC.
        Two commenters (IV-D-25 and IV-F-4, IV-D-34) recommended
   that TOC be used as a surrogate instead of  NMOC,  since it
   would include NMOC as well as other MSW emissions,  and would
   address the global  warming,  explosion, and  fire hazard aspects
   of MSW emissions.   Additionally,  the commenters asserted that
   TOC is less variable,  and sampling and analysis is much less

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  costly.  The commenters suggested that the EPA's sensitivity
  analysis be repeated to select TOC limits.  Another commenter
  (IV-D-54) recommended that VOC be used as the surrogate for
  MSW landfill emissions instead of NMOC.  Other commenters
  (IV-D-26, IV-D-27) also suggested adoption of an alternative
  method for determining applicability of controls and
                                                  •»
  well-spacing using TOC as a methane surrogate.  The commenters
  preferred this method because it will be easy to enforce.
       Response;  The EPA designated MSW landfill emissions as
  the pollutant to be regulated because it contains the various
  landfill air pollutants, including methane and NMOC, posing
  concern due to adverse health and welfare effects.  The NMOC
  may contribute to ozone formation and odor problems.  Some
  NMOC are known or suspected carcinogens, while other NMOC are
  known to cause noncancer health effects.  Methane was also a
  concern, due to the potential it poses for explosions and fire
  and global climate change impacts.
       The EPA decided not to determine control requirements
  based on the methane fraction of MSW landfill emissions
  because the NMOC surrogate is more effective than methane in
  addressing the broad range of concerns posed by MSW landfill
  emissions.  The reduction of methane will, however, be a
  benefit of these regulations.   (Additional methane
  considerations are discussed in section 2.18.1, Consideration
  of Methane.)
       A TOC surrogate may track methane, one of the larger
  fractions of the MSW emission mixture more closely, but would
  not respond to varying NMOC levels as well as the NMOC
  surrogate, because of the dominance of methane.  Therefore, a
  TOC surrogate would not allow the EPA to tailor the
  regulations to the overall environmental concerns of MSW
  landfill emissions.  There has  been considerable concern
  expressed about the toxicity of NMOC.  Given the requirement
  to select BDT considering costs and other impacts, the EPA has
  chosen to base these regulations on an NMOC cutoff, to control
  the subset of landfills presenting the greater health

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   concerns,  rather than base these regulations on emissions of a
   more generic surrogate,  such as TOC.   In this way,  the EPA was
   able to select BDT (based on a cost and impact analysis)
   addressing the landfills that present the greatest overall
   environmental concerns at this time.
        Finally, the EPA does not agree that a TOC surrogate
   would be easier to enforce, because enforcement would depend
   on emission calculations, with opportunity for site-specific
   testing, whether TOC or NMOC provided the basis for control.
        Comment:  One commenter (IV-D-54)  contended that the EPA
   changed the regulated pollutant from VOC to NMOC to force
   State air  divisions to formulate plans to regulate landfill
   emissions  using section lll(d)  technology-oriented standards.
   The commenter also contended that this will subject these
   landfills  to additional PSD review,  which will consume
   valuable State resources.
        Response;  If the EPA had not established a significance
   level for  MSW emissions for inclusion in 40 CFR 51 and 52, MSW
   landfills  would be subject to PSD review whenever any increase
   in MSW landfill emissions occurred.   The 45 Mg/yr (50 tons/yr)
   significance level for NMOC in the final rule is comparable in
   stringency to the 36 Mg/yr (40 tons/yr)  significance level
   established for VOC.   The EPA estimates VOC to account for
   approximately 70 percent of total NMOC from MSW landfills, but
   this percentage varies among landfills.   Landfills with
   emission increases greater than 45 Mg/yr NMOC or greater  than
   36 Mg/yr VOC would be required to undergo PSD review.  The PSD
   significance level for landfill emissions was changed from
   36 Mg/yr (40 tons/yr)  at proposal to 45 Mg/yr (50 tons/yr) to
   be more consistent with the previously established
   significance level for VOC.  The EPA considers the
   significance value appropriate for the health and welfare
   effects of the MSW landfill emissions.
   2.6  SELECTION OF BEST DEMONSTRATED TECHNOLOGY
        Comment;  One commenter (IV-D-15)  requested that the
   stringency of the standards be increased,  so that better

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  technology could be incorporated.  The commenter also
  maintained that BAT should be used in place of BDT to
  encourage continuing research in emissions control.
       Response;  These standards and emission guidelines are
  promulgated under section 111 of the CAA, which requires the
  standards be set based on the application of the BDT
  considering costs and any nonair quality health and
  environmental impacts and energy requirements, at the time the
  standard is promulgated.  An NSPS establishes a nationwide
  minimum level of control, but it is based on the application
  of BDT.  States do, however, have the freedom to set more
  stringent standards, whether through establishing a lower
  regulatory cutoff or requirements for a BACT-type analysis
  whenever a new or modified landfill is permitted.  These
  regulations, however, must conform to the statutory framework
  for NSPS.  Refer to section 2.6.2 for further discussion on
  the selection of the regulatory stringency level.
       Comment;  One commenter (IV-D-21) stated that the
  proposed regulations would discourage owners or operators from
  using alternative control devices, because all control devices
  except open flares would have to demonstrate compliance by
  testing.  The commenter suggested that other control
  technologies, including energy recovery technologies, should
  be defined as BDT.  The commenter requested that, at the very
  least, additional language and guidelines be added to the
  regulation to strongly endorse and encourage energy recovery.
       Response:  The regulation allows any control system
  designed and operated within the parameters demonstrated in
  the performance test to reduce NMOC by 98 weight-percent or
  reduction to 20 parts per million by volume.  The preamble to
  the final rule defines combustion control achieving 98 percent
  reduction or 20 ppmv as BDT.  The rules are not intended to
  encourage open flares instead of energy recovery devices.  The
  regulation does not require testing of open flares because
  testing is infeasible.  However, flares must be designed and
  operated according to specified criteria and visible emission

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   determination is required by 40 CFR 60.18.   Additional impacts
   analyses of energy recovery technologies were performed after
   proposal and the results have been incorporated in the
   preamble of the regulation.  The nationwide impacts of flare
   and energy recovery options are detailed in the memorandum
   "Revised Nationwide Impacts for Development of Regulatory
   Alternatives" (Docket No. A-88-09,  Item No. IV-M-7).
   2.6.1  Selection of Best Demonstrated Technology—Passive
   Systems
   ^"•-^"^"^•^™™—  *
        Comment;  One commenter (IV-D-29)  requested that the
   regulation provide specific criteria and test methods that a
   passive venting system must meet to satisfy BDT.  The
   commenter questioned why the EPA is allowing passive systems
   when it has stated in the 1988 Preliminary  Draft BID that "gas
   captured in a passive system is not amenable to control or
   recovery."
        Another industry commenter (IV-D-27) argued that passive
   systems can be designed to meet BDT, and provided a table
   cross-referencing previous submittals providing useful
   information on such systems.
        One commenter (IV-D-17) stated that the EPA should
   demonstrate the relationship between passive and active
   collection systems.  They further state that if a correlation
   exists, passive systems such as landfill vents could be used
   to predict the performance of,  or need for, active collection
   systems.
        Response;  The EPA investigated the use of passive
   systems prior to proposal, and some design  guidance was also
   provided in chapter 9 of the proposal BID.   The EPA assumes
   that the 1988 preliminary draft BID commenter IV-D-29 referred
   to was an early draft that differs from the BID published at
   proposal in March 1991.   Although the EPA found passive
   systems generally to be less practical and  more expensive than
   active collection systems, such systems may achieve an
   equivalent level of control, provided that  the landfill
   installs and carefully maintains a liner on all six sides of

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  the landfill as required under subpart D, section 258.40 of
  the final solid waste disposal facility criteria regulation
   (56 FR 50978; October 9, 1991).  The owner or operator would,
  however, need to submit a design plan that demonstrates that
  the system provides an equivalent amount of control to an
  active system meeting the criteria in § 60.759 of the NSPS.
  Section 63.752(b)(2)(ii)(B) includes criteria passive
  collection systems must satisfy and a requirement for a design
  plan.  The relationship between passive and active systems
           *
  would depend on site-specific  landfill characteristics and
  system designs.  Based on existing information, it is not
  practical to establish a correlation.  A site-specific design
  approval approach is more appropriate.
  2.6.2  Selection of the Emission Rate Cutoff
       Comment;  Several commenters requested a more stringent
  emission rate cutoff, while others favored the 150 Mg/yr rate
  proposed, and some favored a less stringent standard.  Four
  commenters  (IV-D-18, IV-D-25,  IV-D-34, IV-D-44) supported the
  proposed regulatory emission rate cutoff of 150 Mg/yr.  Some
  of these and other commenters  (IV-D-15, IV-D-18, IV-D-20,
  IV-D-25, IV-D-27, IV-D-34) stated they would support a more
  stringent level.  One of these commenters  (IV-D-20) asserted
  that the data provided by the  EPA supports a more stringent
  level, that this level would not significantly increase the
  control period, and that it would be cost-effective.  Another
  commenter (IV-D-21) stated than an economic analysis including
  energy recovery would support  a more stringent standard, and
  the regulatory cutoff level should be lowered.
       Two commenters (IV-D-11,  IV-D-33) supported a stringency
   level of 25 Mg/yr because of the methane reductions that would
  result.  One of the commenters (IV-D-11) stated that such an
   emission  level would reduce 90 percent of NMOC and 80 percent
   of methane  emissions from MSW  landfills.  The other commenter
   (IV-D-33) presented an analysis to show that NMOC and methane
  reduction from landfills emitting above 25 Mg/yr NMOC is
  cost-effective, particularly if benefits from abatement of

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   global warming and energy recovery are considered.   One
   commenter (IV-L-7) recommended an emission rate cutoff of
   25 Mg because only 10 percent of methane generated by
   landfills is being burned for energy recovery and the
   commenter wanted the rule to encourage the development and
   installation of energy recovery systems.  Another^ commenter
   (IV-D-29) suggested examining a level between 25 Mg/yr and
   150 Mg/yr.  In particular, the commenter claimed that health
   risks posed by landfills between these two cutoff levels may
   be significant.
        Another commenter (IV-D-39) stated that the BID and RIA
   for the proposal do not provide a clear rationale or cost
   effectiveness for the selection of a 150 Mg/yr NMOC emission
   limit.  The commenter asserted that, because of the
   uncertainty in the actual benefits (i.e., health and
   environmental), an emission rate cutoff of 250 Mg/yr could
   have been justified.   This commenter stated that the data
   necessary to adequately characterize the environmental
   benefits of the proposed regulation should be collected prior
   to setting an emission rate cutoff.
        One industry commenter (IV-D-27 and IV-F-5)  requested
   that the EPA fully reevaluate the 150 Mg/yr cutoff after
   correcting for a reported incorrect conversion factor and
   recalculating the defaults.
        Response:   Prior to proposal, the EPA considered setting
   a  more stringent cutoff but concluded that the data available
   at that time best supported the 150 Mg/yr level.   As explained
   in the proposal preamble,  preliminary evaluations were
   performed on several  different emission rate cutoffs, ranging
   from 25 to 500  Mg/yr.   Three regulatory alternatives were then
   chosen for more rigorous review:  25 Mg/yr (Alternative 1),
   150 Mg/yr (Alternative 2), and 250 Mg/yr (Alternative 3)  NMOC.
   The alternatives provided the basis for the selection of BDT.
        Based on consideration of the emission reduction
   estimated at proposal  and other factors specified in section
   111 including health  and environmental impacts,  energy, and

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  cost, 150 Mg/yr of NMOC was proposed as the emission rate
  cutoff in these regulations (56 FR 24468, May 30, 1991).
       As a result of the changes in the data and methodology
  for estimating emissions and costs for control of MSW landfill
  emissions, and in the response to the public comments, the
  regulatory alternatives and the estimates of the emission
                                                  • \
  reductions and the control costs of alternative stringency
  levels were revised after proposal.  The changes in the data
  and methodology for estimating emissions and costs are
  described in the memoranda "Methodology Used to Revise the
  Model Inputs in the Municipal Solid Waste Landfills Inputs
  Databases"  (Docket No. A-88-09, Item No. IV-M-4) and "Changes
  to the Municipal Solid Waste Landfills Nationwide Impacts
  Program Since Proposal"  (Docket No. A-88-09, Item No. IV-M-3),
  and were summarized in the supplemental notice of data
  availability in the Federal Register  (58 FR 33790,
  June 21, 1993).
       The proposal value of 150 Mg/yr is now estimated to
  affect less than 2 percent of the landfills, obtaining only
  45 percent NMOC and 24 percent methane emission reduction with
  an average cost effectiveness of $800/Mg NMOC for new
  landfills and $750/Mg NMOC for existing landfills.  Therefore,
  more stringent cutoffs were evaluated.  At a cutoff of
  50 Mg/yr, 5 percent of the landfills would install controls
  with an NMOC reduction of 53 percent and a methane reduction
  of 39 percent.  The average cost effectiveness of this option
  is $l,200/Mg NMOC for new and existing landfills. The
  incremental cost effectiveness of going from a 150 Mg/yr
  cutoff level to a 50 Mg/yr cutoff level is $2,900/Mg for new
  landfills and $3,300 Mg  for existing  landfills.  The
  incremental cost effectiveness of cutoffs lower than 50 Mg, or
  no cutoff would be unreasonable.  Based on the revised impacts
  analyses and the criteria for setting NSPS under section 111,
  50 Mg/yr of NMOC was chosen as the emission rate cutoff.
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   2.6.3  Requirements for Control Equipment
        Comment;   Two conunenters (IV-D-27, IV-D-41) requested
   that testing requirements for enclosed flares be eliminated if
   their design specifications report at least a 98-percent
   destruction efficiency.  One commenter (IV-D-41) stated that
   both open and enclosed flares can achieve 98 percent
                                                   • %
   efficiency, while the other commenter (IV-D-27) provided
   additional emission information to demonstrate that enclosed
   flares, when properly designed and operated, can meet
   98-percent destruction efficiency.  Two industry conunenters
   (IV-D-27, IV-F-6) opposed the provisions for emission sampling
   and testing for enclosed combustors (e.g., enclosed flares)
   arguing that these flares are more efficient than open flares,
   for which performance tests are not required.  Another
   commenter (IV-D-39) contended that the same testing be
   required for all control devices, stating that it is not clear
   why performance tests are not required for open flares.  Two
   commenters (IV-D-27 and IV-F-5,  IV-D-39)  also recommended that
   a performance  standard for enclosed flares be developed to
   replace the testing requirements, while another commenter
   (IV-D-41) requested that the design guidelines include
   operating temperature, flow rate, and residence time for
   enclosed flares.
        Two conunenters (IV-D-19, IV-D-27) recommended that the
   EPA identify both open and enclosed flares as BDT,  and allow
   owners and operators to choose between the two options.
   Another commenter (IV-D-29)  stated that their State requires
   all new flares to be enclosed.   The commenter suggested that
   the regulations require that previously-installed open flares
   be allowed to  continue operation as long as they meet the
   stated requirements.   The commenter also suggested basing the
   regulation on  enclosed flares because they are more easily
   tested,  are quieter than open flares,  and have no visible
   light.   Another commenter (IV-D-41)  pointed out that open
   flares present a visual nuisance.
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       Response;  The BDT for landfills is a collection system
  and a combustion device.  The combustion control device must
  be capable of reducing NMOC emissions by 98 percent or to an
  outlet concentration of 20 ppmv, dry basis, as hexane, at
  3 percent oxygen.  Both open flares and enclosed combustion
  devices that achieve this performance level are BJDT and can be
  used to meet the standards.  Although performance testing is
  the norm under section 111, it is impractical to require
  testing of percent reduction from open flares, because outlet
  concentration is infeasible to measure.  The EPA developed
  40 CFR 60.18 to address this problem.  The provisions for open
  flares in § 60.18 resulted from extensive testing by the EPA
  demonstrating that properly operated open flares achieve
  98 percent destruction efficiency.  This testing would,
  however, be too expensive for an individual owner or operator.
  On the other hand, the performance testing for enclosed flares
  and other enclosed combustion devices, is feasible.  Thus, the
  EPA considers required testing to be warranted for enclosed
  flares consistent with the requirement for testing percent
  reduction for other enclosed combustion devices, such as
  incinerators.
       States may impose additional requirements or restrictions
  on the types of control devices used to address local concerns
  such as noise and aesthetics.  The fact that enclosed flares
  are quieter and less visible does not mean that they provide
  improved emission control over open flares.
       Comment;  One commenter  (IV-D-37) requested that the EPA
  explore the possibility of including NOX and CO limits in the
  standards in order to reduce ozone formation and improve air
  quality.
       Response;  The EPA appreciates the commenter's concern
  about NOX and CO emissions from MSW landfills.  In the
  development of these standards, however, there were
  insufficient data available for proposal of additional
  standards for control of NOX and CO.  Moreover, NOX and CO
  concerns are addressed through the State Implementation Plans

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   (SIPs).   States having NOX or CO concerns may address these
   pollutants both through their SIPs and through establishing
   more stringent standards for new sources under individual
   State regulations.
        Comment;   One commenter (IV-D-38) stated that enclosed
   combustors reaching the required 20 ppmvd of NMOC as hexane
   may, in some cases, only meet a destruction efficiency of
   93 percent or less, instead of the 98-percent reduction of
   NMOC required in the proposed NSPS.
        Response:   The 20 ppmv alternative requirement to the
   98-percent reduction of NMOC was established for the cases
   where the initial NMOC concentration in the collected gas at
   the combustor inlet is so low that demonstration of a
   98-percent reduction would be infeasible.  Thus, there are
   times when less than 98 percent reduction is achieved, but
   these are in cases where the inlet concentration is low and a
   higher percent  reduction is difficult to achieve.  The
   alternative is  appropriate under the NSPS because technical
   feasibility, cost, and demonstrated level of performance are
   considered in the selection of BDT.  While 98 percent
   reduction cannot be demonstrated for all gas streams, 20 ppmvd
   can be achieved.
        Comment;   Five commenters (IV-D-2,  IV-D-18, IV-D-19,
   IV-D-27,  IV-D-29)  addressed some aspect of I.e.  engines.  One
   commenter (IV-D-18) agreed that if lean-burn I.e. engines are
   to be used in nonattainment areas,  they should be capable of
   achieving a 98-percent destruction efficiency.  One of the
   commenters (IV-D-29)  reported that I.e.  engines having permit
   conditions of 98-percent destruction efficiency had been
   installed at local landfills, but they had not yet received
   the compliance  tests for review.
        One  commenter (IV-L-1)  stated that the EPA should exclude
   I.e. engines from those control devices deemed to be BDT and
   adopt technology specific performance standards.  The
   commenter (IV-L-1) noted studies on landfill gas control
   devices in Germany and Montgomery County, Maryland that

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  reported the multipathway cancer risk associated with dioxin
  emissions for a 1,500 ton per day landfill using an I.e.
  engine were as much as 5 x 10""6.  The commenter (IV-L-1)
  stated that the risk for a landfill using a flare is
  0.6 x 10~6.
       The commenter  (IV-L-1) also stated that the.California
  Air Resources Board (CARB) has calculated NOX and CO emissions
  from a 1,500 ton per day landfill using an I.e. engine to be
  379 and 452 tons per year, respectively.  The commenter noted
  that these levels of emissions qualify these sources as major
  under both PSD and nonattainment area new source review
  regulations and that CARB has adopted rules limiting NOX and
  CO emissions to 0.006 and 0.02 Ib/MMBtu for any treatment
  system requiring 98 percent NMOC destruction.
       Another commenter (IV-D-2) also did not support the use
  of I.e. engines as a control device, and stated that I.e.
  engines are not as efficient as other control devices and may
  add to the formation of carcinogens.
       One industry commenter  (IV-D-27) reported that leanburn
  I.e. engines are appropriate and capable of meeting the
  98-percent destruction efficiency criteria on an average
  basis.  The commenter noted that the reduced load periods
  reported as a concern in the preamble are unavoidable but
  infrequent, and would not threaten achieving 98 percent
  destruction on average.  The commenter argued that lowering
  the 98-percent destruction efficiency requirement would only
  reduce the incentive for vendors to produce these engines with
  that level of efficiency.
       Response;  The EPA selected a 98-percent reduction as the
  level representing BDT for control because this is the level
  achievable by demonstrated technologies.  The EPA has
  determined that this level is reasonable considering costs,
  energy, and other environmental impacts.  Thus, the
  regulations will require all control devices to demonstrate
  98 percent reduction or an outlet concentration of 20 ppmvd of
  NMOC, as hexane.  Commenters have not provided data showing

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   that a lower performance level is appropriate for I.e.
   engines.
        Office of Research and Development (ORD) experts believe
   that conditions for dioxin formation are not favorable.   There
   is very limited data available on this,  and for studies  such
   as the German and Maryland ones mentioned in the commenter,
                                                   • %
   the data have low quality assurance.  After a review of  the
   information available,  the EPA has determined that benefits  of
   LFG reduction far outweigh the uncertain concerns of secondary
   pollutants generated.  However, States that have concerns
   regarding the use of I.e. engines can specifically disallow
   them.
        In the development of these standards, there were
   insufficient data available for proposal of additional
   standards for control of NOX and CO.  States having NOX or.CO
   concerns may address these pollutants both through their SIP
   and through establishing more stringent standards for new
   sources under individual State regulations.
        Comment;  One commenter (IV-L-6)  was concerned that the
   EPA had not acknowledged the role that air pollution control
   costs for NOX emissions, especially in ozone nonattainment
   areas,  may play in the selection among flares,  I.e. engines,
   and turbines as the least cost option for control.   The
   commenter (IV-L-6)  included NOX emission information for
   flares, I.e.  engines, and turbines.   The commenter (IV-L-6)
   requested that the EPA make sure that control systems are not
   inappropriately subject to LAER and offset requirements
   pursuant to the CAA.
        Response:  There are numerous factors that affect a
   facility's decision on an appropriate control device for a
   given landfill: ability to sell energy from energy recovery
   devices,  ability to switch control device during a landfills
   history,  community attitudes,  financial restrictions, age of
   the landfill, length of time control is necessary,  attainment
   status, location,  etc.   The least cost analysis was performed
   on a nationwide basis as an indication of how many landfills

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  might be able to use energy recovery as a savings on control
  costs.  It was not meant to be a landfill specific analysis
  where all factors affecting the landfill were included.  The
  facility will have to consider many factors when selecting the
  means of control for a given landfill including the attainment
  status of their area.  If LAER and offset requirements are
  triggered by the emissions from the control device chosen, it
  is appropriate that these requirements be met.  It should also
  be noted that controls added to comply with the landfills rule
  may, at the discretion of the State, qualify for the pollution
  control exemption from NSR.
       Commenter:  One commenter (IV-L-1) contended that
  additional impacts from the purification of landfill gas are
  not addressed in the proposed NSPS.  The commenter contended
  that emissions associated with any treatment or regeneration
  of molecular sieves or other equipment employed to achieve
  purification; and the need to control water quality impacts
  from  (a) the discharge of the blowdown and wastewaters from
  both the purification and regeneration steps and  (b) the
  condensate removed from the gas collection systems should be
  considered.
       Response;  The rule does not specify the types of control
  devices that must be used, only that equipment achieve
  98-percent reduction of NMOC or 20 ppmvd.
       The nationwide impacts estimate considered the cost of a
  flare for each landfill, which did not require costs of
  purification.  In the nationwide impacts estimate under the
  energy recovery scenario, costs were included for filtering
  the gas prior to an I.C. engine.  The cost for handling
  condensate removed from the gas collection system was also
  included in the analysis; however, the rule does not specify
  handling methods or techniques.
        For further information on comments received on the
  handling of gas condensate and the EPA's response see
  section 2.16.3 "Subtitle D Interface" of this chapter.
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   2.7  FORMAT OF THE STANDARD
        Comment;   One conunenter (IV-D-37)  stated that the format
   of their State regulation (California Model Regulation) for
   measuring emission rates and determining whether controls are
   required is simpler than the proposed regulation.  In the
   State regulation,  any site with greater than 500,000 tons of
                                                   •«
   waste must install gas collection systems,  unless the owner or
   operator can demonstrate there are only small amounts of
   surface emissions.  The conunenter suggested that no landfills
            *
   having less than 500,000 tons of waste-in-place would ever be
   required to install controls under the proposed regulation
   anyway.
        One commenter (IV-D-26) stated that it would be easier to
   use a total "tonnage in place" as a trigger to install active
   gas extraction systems as opposed to the tiered approach.  The
   commenter contended that because of the conservative default
   values,  the Tier 1 calculation becomes academic and the
   "tonnage in place" trigger would be a suitable alternative.
        Response;   The purpose of this regulation is to reduce
   MSW landfill emissions or LFG,  the designated pollutant.
   Landfill gas is comprised of methane, CO2,  and NMOC, and
   emission rates of  these compounds vary from
   landfill-to-landfill,  even when refuse in place (RIP) is
   virtually identical.
        Early in  the  development of these regulations, the EPA
   proposed to base applicability of controls  for MSW landfills
   on RIP,  and a  RIP  of 1 million Mg was selected.   This format
   was presented  at the NAPCTAC meeting in May 1988.  Both
   NAPCTAC members and industry representatives advised that,
   size and/or RIP were not sufficient basis for determining that
   control or exemption from control is appropriate because of
   variability of  emission levels from landfill to landfill.
   (See Docket No.  A-88-09,  Item No.  II-B-15.)
        As discussed  in the proposal preamble  under "Format for
   Applicability," the EPA found that the NMOC emission rate
   format achieved a  greater emission reduction for lower costs

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  than a RIP format.  The proposed NSPS combined a design
  capacity exemption level of 100,000 Mg with an NMOC emission
  rate trigger for control.  The design capacity exemption was
  reevaluated in the interim between proposal and promulgation
  after review of additional data regarding gas generation
  rates, and has been revised to 2.5 million Mg or
  2.5 million m3.  The revised cutoff would exempt approximately
  90 percent of landfills from the testing and recordkeeping
  required under the NSPS and EG, while only 15 percent of the
           •
  potential NMOC emission reductions would be lost.
       Comment;  Eight commenters  (IV-D-25, IV-D-26, IV-D-31,
  IV-D-34, IV-D-37, IV-D-39, IV-D-55, IV-F-4) supported a
  performance based standard.  Some of these same commenters
  (IV-D-25, IV-D-26, IV-D-31, IV-D-34, IV-D-55) noted that
  generated MSW gas does not equal emitted gas and indicated  the
  standard be based on measurement of gas emitted.  One
  commenter (IV-D-31) suggested the use of flux box testing or
  monitoring concentrations of methane (as a surrogate for
  NMOC).
       Four commenters  (IV-D-25, IV-D-34, IV-F-4, IV-D-55)
  supported a performance standard based on TOC levels.  The
  commenters further suggested that the performance standard  be
  tailored after SCAQMD field monitoring based performance
  standards, which specify that the maximum concentration of
  methane at any point on the surface of the landfill cannot
  exceed 500 ppmv, and that the average concentration cannot
  exceed 50 ppmv.  One commenter  (IV-D-26) stated that the
  California approved surface testing methods should be allowed
  as a means to determine if controls are needed.  Another
  commenter (IV-D-55) also contended that because there is no
  performance standard for the collection system, there is no
  requirement to confirm that the  collection system is
  performing adequately.  One commenter  (IV-D-26) contended that
  the EPA monitoring method for subsurface measurement of NMOC
  is very costly and fails to focus on the true problem of
  surface emissions of LFG and NMOC.

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        One commenter (IV-D-37)  discussed their State's
   performance-based regulation for reduction of NMOC.  This
   regulation was based on actual landfill testing, which
   revealed that at least one of the 10 air contaminants present
   in LFG was found at 70 percent of landfills.  Underground
   migration of methane was a problem at 20 percent of the sites.
                                                   • %
   Their state regulation differs from the proposed standard in
   that it contains different provisions concerning which
   landfills should be controlled,  collection efficiency, and its
            •
   requirements for control system design, reporting,
   recordkeeping and compliance.  The commenter noted that
   although the proposed regulations provide design flexibility
   and encourage States to allow flexibility, their State's
   regulation was simpler than the proposed standards.
        Two commenters (IV-D-25, IV-D-34)  asserted that the EPA
   had not met its statutory obligation to demonstrate that it is
   infeasible to set a performance standard prior to setting a
   design standard for control of landfill emissions.   The
   commenter asserted that the performance-based SCAQMD landfill
   regulation achieves 90 percent TOC destruction efficiency and
   demonstrates that a performance standard is feasible.
        One commenter (IV-D-39)  suggested that a performance
   standard based on an emission limit be proposed for
   controlling air emissions at  MSW landfills and that the method
   of achieving the emission limit should not be specifically
   addressed by the regulation.   The commenter argued that by
   establishing very specific design,  operational and work
   practice standards, the system will not function optimally and
   cannot incorporate innovation in design.   The commenter said
   that an emission limit of 150 Mg/yr of NMOC alone will provide
   the same level of environmental protection as the combined
   design,  equipment,  and work practice standards, and allow
   designers of LFG systems the  flexibility needed to optimize
   the design to fit the specific landfill situation.
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       The commenter also stated that the courts have expressed
  a clear preference for the development of emission standards
  as opposed to design, operational and work practice standards.
       Another commenter  (IV-D-55) noted that little if any NMOC
  passes through the soil and that most of the emission release
  points are through holes and channels.  The commenter stated
                                                  • %
  that with the notable exception of vinyl chloride and a few
  other trace compounds, the primary source of NMOC is the
  evaporative emissions of leachate.  The commenter recommended
           •
  that leachate exposure be prohibited anywhere on the surface
  of the landfill.
       Response;  A performance standard is not appropriate for
  gas collection system design because it is not feasible to
  measure gas generated versus gas collected at a landfill and
  determine what performance a collection system is achieving.
  Monitoring surface concentration alone also does not
  demonstrate what fraction of gas is being collected or whether
  the system is designed and performing optimally.  However,
  monitoring surface concentrations will indicate when cover
  maintenance and well adjustments should be made as well as
  when additional wells should be added.  Surface monitoring
  will also provide a safeguard against uncertainties in area of
  influence determinations.  Surface emission monitoring is
  discussed in section 2.12.1 of this chapter.
         Because a performance standard is not feasible, a
  design and operational standard has been set as BDT for gas
  collection system design.  The specifications for active
  collection systems do not give prescriptive design
  specifications; rather, they present criteria on which to base
  a collection design plan.  All owners or operators must submit
  their collection system design plan to the Administrator for
  approval.  The purpose of collection and control equipment is
  to capture and control gas generated within the landfill.  The
  collection system must be installed within 1-1/2 years of the
  design plan submittal or notification of intent to install.
  In addition to the criteria in S 60.759, the collection system

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   must also meet the four criteria specified in
   S 60.752(b)(2)(ii),  which states that:   (1)  the collection
   system design plan must be prepared by a professional
   engineer, and designed to handle the maximum expected gas flow
   rate over the intended equipment use period, (2)  gas must be
   collected from all active areas in the landfill in which
                                                   • %
   refuse is more than 5 years old, and from all closed areas (or
   areas at final grade) in which refuse is more than 2 years
   old, (3) gas must be collected at a sufficient extraction
            *
   rate, and (4) the collection system must be designed to
   minimize off-site migration of subsurface gas.
        As discussed in the preamble to the proposal (see
   56 FR 24484; May 31, 1991), to establish an emission limit or
   performance standard for collection, the exact quantity of gas
   being generated by each area of the landfill would need to.be
   quantified,  and then the reductions achieved would need to be
   compared to it.   This is technically infeasible.   Estimates
   vary regarding the actual percentage of produced gas that can
   be collected, anywhere from 50 to 90 percent, but the EPA and
   industry alike recognize that these are only estimates.
   Therefore,  design and operational standards were set for the
   collection system.
        A performance standard was, however,  set for the control
   device, because once the gas has been collected,  the
   destruction efficiency of the control device can be
   established.  Landfill owners or operators using the SCAQMD
   approach can submit designs to the State as provided in
   40 CFR 60.752(b)(2)  or 40 CFR 60.33c(b).  The regulations
   allow the flexibility to use alternative gas collection and
   control systems as long as they are demonstrated to be as
   effective as a system designed to meet the criteria in
   S 60.759. [See 40 CFR 60.752(b)(2)(i)].
        In response to commenters who indicated that gas emitted
   was not equal to gas generated,  as explained in the proposal,
   the NSPS and emission guidelines address all of the MSW
   landfill emissions generated within the landfill,  and not just

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  those emitted through the cover.  The NMOC can be emitted in
  several ways:  through the landfill cover, through holes and
  channels, through evaporation of leachate, or through
  underground offsite migration through the soil.  The EPA
  considers the primary source of NMOC emissions to result from
  transport and stripping by methane-laden gas as it migrates
                                                  • *
  through the soil/refuse.  Diffusion and displacement are also
  transport mechanisms that impact the NMOC emission rate.  No
  matter how the NMOC migrates to the atmosphere, a
           •
  well-designed gas collection system will minimize the
  potential for NMOC emissions with the most confidence.
       The commenter (IV-D-55) did not provide documentation on
  the evaporative emissions from leachate and its contribution
  to NMOC emissions.  Leachate on the landfill surface is
  addressed under RCRA.
  2.8  NATIONWIDE IMPACTS
       Comment;  One commenter  (IV-D-17) suggested that the
  proposed emission estimates may lack accuracy because of
  variations in the types of waste that landfills accept and the
  limited availability of records estimating the decomposable
  amounts of waste.  A second commenter (IV-D-55) was concerned
  that the estimated potential reductions are overstated and are
  in conflict with CARB estimates, the EPA's own emissions
  inventory factors (Procedures for the Preparation of Emission
  Inventories for Precursors of Ozone, EPA-450/4-88-021,
  p. 4-31), and district field data.  The commenter recommended
  that the calculated NMOC emission reductions should be
  confirmed and resolved with other conflicting emission
  estimates.  The commenter also suggested that this data be
  published and submitted for public comment before the data is
  used.
       Response;  The nationwide impacts were developed using
  data from the OSW landfill survey, which provided information
  from a large number of landfills; information about NMOC
  concentration and methane generation from section 114
  responses and industry submittals; and additional EPA studies.

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   The information from the OSW survey consisted of landfill
   location,  annual waste acceptance rate,  refuse in place in
   1987, age, depth and design capacity for 931 landfills.  The
   information on NMOC concentration and methane generation used
   at proposal was randomly assigned to the landfills from the
   OSW survey because this information was  not included in the
   survey.   This additional information was randomly assigned in
   order to represent the variability reported by industry, and
   referred to by the first commenter.
           *
        In  the interim between proposal and promulgation of these
   regulations,  additional NMOC concentration and methane
   generation data were obtained,  and the methodology for
   randomly assigning the data to  the landfills from the OSW
   survey was revised.   These changes are described in the
   memorandum "Methodology Used to Revise the Model Inputs in the
   Municipal  Solid Waste Landfills Input Data Bases (Revised)"
   (Docket  No.  A-88-09, Item No. IV-M-4).  The EPA considers the
   large database of landfills and the assignment of Lo and CNMQC
   values to  reasonably represent  the variability among landfills
   in the U.S.   This methodology best represents the variability
   reported for landfills.   If an  emission  factor method had been
   used, variations in waste composition, age, landfill
   geography, etc., would have no  opportunity to impact the
   results.
        The NMOC emissions reductions were  estimated by the EPA
   using a  modification of the Scholl Canyon model and a range of
   NMOC values  obtained from test  data.   Because of the change in
   emissions  over time and the varying emission levels from
   landfill to  landfill,  nationwide emissions and emissions
   reductions are best described in terms of NPV.   This approach
   accounts for the variations noted and presents the emissions
   on a normalized basis for comparison between different
   emission rate cutoffs.   The emissions estimates calculated
   using the  commenter's data would result  in annual emissions,
   which cannot be compared to the net present value.
   Furthermore,  the EPA's approach accounts for the emissions

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  resulting from each subpart of mass at various ages, while the
  emission inventory factor is constant and would overestimate
  emissions when used with net present value calculations.
                 One commenter (IV-D-26) submitted test data on
  NMOC concentrations ranging from 300 to 7,500 ppmv.
       Response ;  All values for which the EPA had adequate
  documentation were used in estimating national impacts of the
  NSPS and EG.  Some of the NMOC concentrations submitted by
  commenter IV-D-26 were sufficiently documented to be included
           •
  in the data bases.  However, the NMOC concentrations for use
  in the nationwide impacts were reevaluated and assigned to the
  input data bases before the values provided by the commenter
  were received.  The values submitted by commenter IV-D-26 fit
  within the revised range of NMOC concentrations used in
  developing the final nationwide impacts.  The EPA determined
  that incorporating the NMOC concentrations provided by the
  commenter would not significantly change the estimated impacts
  of the regulations, and, therefore, additional resources were
  not expended to incorporate the additional concentrations into
  the data bases.
       Comment ;  One commenter  (IV-D-22) suggested that the EPA
  further investigate the effects of moisture on methane
  generation.  The commenter proposed evaluating the effect
  capping with a geomembrane would have on the moisture content,
  as well as the methane generation rate.
       Response;  The EPA considered such variability in
  moisture content early in the development of these
  regulations.  However, moisture content varies based on
  geography, topography, and even management practices, such as
  cover types and maintenance procedures.  Although it is
  infeasible to incorporate all these site-specific factors in
  the model, the impacts of these factors would be accounted for
  if gas production testing were performed at the landfill, as
  in Method 2E, or NMOC concentration was measured, as in
  Method 25C.  The EPA acknowledges that the use of a
  geomembrane or other effective cover will reduce moisture

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   content to some degree.   However,  at this time the impact of
   the use of a geomembrane is unknown, and therefore, was not
   included in the model.
        During the interim between proposal and promulgation of
   these regulations,  the EPA incorporated location within an
   arid or nonarid region in the analysis.  The site-specific
                                                   • %
   methane generation data were categorized as arid or moist
   based on the location of the landfill from which the data were
   generated.  The methane generation data were assigned to the
           •
   input data bases in proportions to represent the amount of
   waste and the number of landfills  located in arid and moist
   regions of the United states.  This methodology is described
   in the memorandum "Methodology Used to Revise the Model Inputs
   in the Municipal Solid Waste Landfills input Data Bases
   (Revised)" (Docket No.  A-88-09, Item No. IV-M-4).
        Comment:  One industry commenter (IV-D-27) contended that
   the EPA overestimated the number of new MSW landfills opening
   in the first 5 years of the regulations, and that this number
   will be smaller because of the combined impact of the proposed
   regulations,  new subtitle D regulations, transport
   restrictions, waste reduction and  recycling programs, and the
   NIMBY syndrome.   The commenter criticized the Agency
   assumption that existing landfills would be replaced with new
   landfills having similar characteristics as they closed,
   noting that the State of the art of landfill design,  and
   growing State and Federal restrictions would result in
   "different" landfills.
        Another commenter (IV-D-39 and IV-F-3)  stated that more
   landfills will actually be affected than the EPA had stated,
   because there are now approximately 7,500 landfills instead of
   the 6,000 that the EPA reported to exist in 1987.
        Response;  The EPA is not certain that fewer landfills
   will be opened.   It is  precisely this inability to predict the
   exact characteristics of future landfills that led to the
   decision to model new landfills based on the current
   characteristics of  landfills.  If  fewer landfills will be

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  opened, these  landfills may  be  larger, resulting  in  a  lower
  costs per Mg of emission reduction.
       To estimate the  impacts of the regulation through 1997,
  the  EPA modeled landfills  opening  after  1987 based on  the
  population  of  landfills in 1987.   The EPA  estimates  that
  approximately  7,440 landfills existed in 1992, which
                                                  ' *
  corresponds to the estimate  of  7,500 provided by  the
  commenter.
  2.8.1  Cost Impacts
       Comment;  Several commenters  (IV-D-39 and IV-F-3,
  IV-D-46,  IV-D-55, IV-F-4) stated  that the EPA underestimated
  costs for gas  collection systems.  One commenter  (IV-F-4)
  contended that the underestimation resulted from  the analysis
  being based on large  landfills.  The commenter asserted that
  the  uncertain  service life of system components may  contribute
  to additional  nationwide costs.  Another commenter  (IV-D-39
  and  IV-F-3) stated that the  underestimation resulted from
  incomplete  data.  Other commenters (IV-D-55, IV-F-4) argued
  that the design specifications  and proposed method for well
  spacing would  increase the program costs without  added
  benefit.
       One commenter  (IV-F-5)  stated that  the cost  of  many of
  the  monitoring provisions, such as temperature indicators,
  flow indicators, heat sensing devices, pilot flame indicators,
  and  wellhead pressure gauges, may  be too burdensome.
       One commenter  (IV-D-53)  stated that small landfills are
  experiencing financial hardships due to  the increasing number
  of new landfill regulations.  The  commenter was opposed to any
  regulations that are  extremely  costly or technically unsound.
       One commenter  (IV-D-52)  expressed concern for taxpayers
  who  are constantly being asked  to  pay for  new regulations.
  The  commenter  suggested that the proposed  regulations  should
  focus on using control methods  already in  practice at  larger
  facilities.
       Two commenters  (IV-D-25, IV-D-34) reported that
  preliminary information from the SWANA survey of  selected

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   collection system owners and operators indicated that the
   EPA's cost projections were too low due to underestimating
   system capital and operational and maintenance costs.   The
   commenters further argued that because the modeling
   assumptions result in inflated emission rates, the cost
   effectiveness of the standard is also skewed.   One of the
                                                   '»
   commenters (IV-D-25)  noted that all of the data received in
   response to the survey would be reviewed and submitted for
   Agency review.  (These surveys, along with a cost analysis,
            •
   were submitted to the EPA and reviewed.  See Response for
   details.)
        Response;  The cost impacts were determined using data
   from the OSW data base, section 114 responses, industry
   information voluntarily submitted over the course of
   regulatory development, and standard engineering sources.  .The
   collection system design for the proposed regulations was
   similar to systems in place at many landfill sites,  and
   information on component design included data gathered both
   from collection system operators and vendors.   The cost basis
   for the proposed regulations were presented in chapter 7 of
   the proposal BID.   However,  to provide flexibility and reduce
   costs,  the EPA removed the prescriptive design specifications
   for gas collection systems and replaced them with design
   criteria.  This allows owners and operators to design the most
   cost-effective gas collection system (meeting certain minimum
   requirements)  for their landfill.
        As stated in the proposal BID, the OSW data base, which
   made up the overall structure of the data base used for the
   cost impacts,  included 151 large landfills and 780 small
   landfills.   The EPA is satisfied that large landfills were not
   over represented.
        Nationwide control costs were developed by designing and
   costing a control  system for each landfill in the data base,
   and these costs were  determined to be reasonable for most
   landfills which would require control at the proposed
   regulatory emission rate cutoffs.  Also,  the design capacity

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  exemption was reevaluated in the interim between proposal and
  promulgation, and has been revised to 2.5 million Mg.
  Landfills with a design capacity less than 2.5 million Mg will
  not be affected by the final regulations.  Therefore, small
  landfills will not be adversely impacted by the regulation.
       Both collection and control system design and costing
                                                  • x
  were developed with a high level of industry participation
  (see Docket A-88-09, categories II-C and II-D).  The service
  lives of blowers, motors, turbines, and flares were considered
  in the proposal and promulgation cost impacts analysis.
  Consideration of I.e. engine and well service lives were added
  to the promulgation cost impacts analysis.  The final cost
  analysis presents a reasonable estime  on of cost impacts that
  are to be representative of both large and small landfills.
       The monitoring provisions in the final standards are
  typical of monitoring provisions under the NSPS program for
  similar control equipment, and are necessary to ensure proper
  operation of the equipment, and to avoid fire or explosion
  hazard.  However, since proposal the EPA has provided for the
  option of monitoring of bypass systems rather than monitoring
  flow to a control device.  The use of flow indicators in
  bypass lines or the use of bypass systems with car-seals, lock
  and keys, or other configurations that provide a record of
  bypass system use may reduce the monitoring burden associated
  with the monitoring of flow to the control equipment.  The EPA
  determined that the monitoring costs of the final regulations
  were reasonable and necessary to ensure proper operation of
  collection and control equipment.
       The EPA received and reviewed the SWANA survey and
  associated cost analysis.  The EPA cost numbers, at first
  review, appear lower than the survey results.  However, the
  costs analyses presented in the proposal BID were based on
  equipment costs in  1987 dollars, several years before the
  SWANA survey was conducted.  Also, the EPA cost impacts
  analysis at proposal was a rigorous two-stage time accounting
  of dollars in 1992 NPV.  The SWANA cost analysis is a

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   summation of dollars expressed in varying years.  If the SWANA
   data were in a form which could be utilized in its nationwide
   impacts model, the results would not differ significantly.
        The EPA considers that the information provided by
   respondents to the EPA's section 114 information requests was
   accurate, and was generally provided in direct response to
                                                   • %
   specific questions.  The SWANA survey was not conducted under
   such rigorous conditions or requirements, and consequently did
   not provide as specific a system or cost breakdown.
            •
   Additionally, the SWANA costing survey compiled answers from
   only 13 actual landfill collection systems, managed by five
   individuals or organizations and, therefore, did not represent
   a large increase in information.   However,  The EPA did utilize
   the results of the SWANA survey wherever possible, such as in
   developing time frames for system component replacement.
        Comment;  One commenter (IV-L-3)  maintained that cost
   information is readily available only from certain vendors and
   major gas system developers.  The commenter (IV-L-3) was
   concerned that the cost information used in the development of
   the regulations is not representative, particularly for
   smaller developers.  The commenter (IV-L-3) maintained that
   small developers will not enjoy economies of scale and
   recommended that the cost analysis account for varying
   economies of scale for equipment purchases and operation and
   maintenance services.
        The commenter (IV-L-3)  cited the EPA report,  "Landfill
   Gas Energy Uses:   Technology Options and Case Studies."  The
   commenter (IV-L-3)  stated that this report shows 1992 median
   I.e.  engine costs of about $1,300 per kilowatt.   The commenter
   (IV-L-3)  also cited a George Jansen,  of Laidlaw, report, "The
   Economics of Landfill Gas Projects in the United States"
   presented in Australia in February of 1992.  The commenter
   (IV-L-3)  stated that this report estimated I.e.  engine system
   costs of $1,500 per kilowatt.   The commenter (IV-L-3)
   contended that when the economy improves, the costs of
   installation for electrical projects may increase towards a

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  value of $1,200 to $1,500 per Kilowatt of installed capacity,
  not the $1,000 we see today.  The commenter (IV-L-3) stated
  that the Jansen report has good cost insights which should be
  more representative of an average economy.
       The conmenter (IV-L-3) also listed other factors and
  obstacles that make capital and operations costs higher,
                                                  • x
  including distance from transmission lines, difficulty in
  getting needed water, and difficulty with permitting.  The
  commenter  (IV-L-3) recommended that the EPA reexamine the
  various gas to energy implementation and operational costs.
       Response;  The cost figures were meant to be an average
  cost that could be applied to various energy recovery projects
  across the Nation, in order to develop nationwide cost
  estimates.  It is true that small developers may have to pay a
  higher fee than larger developers, and some developers will
  pay a lower fee because of their location.  The EPA does not
  contend that all developers will pay the same price, but does
  consider the costs applied to be average costs suitable for
  nationwide impacts estimates.
       The costs that were used for I.e. engines were based on
  information from two I.e. engine vendors and a vendor-referred
  contractor.  These vendors supply many of the I.e. engines
  used for landfill gas combustion.  The calls collecting the
  data were made in early 1992.  At this time, neither the EPA
  report or the George Jansen report were available to the EPA.
  The EPA used the best data available at the time.  In
  addition, the I.e. engine cost used in the nationwide impacts
  analysis is still within the range of the I.e. engine costs
  predicted by the EPA report.  The EPA report cites I.e. engine
  costs in the range of $1,000 to $2,500/kW with lower costs for
  smaller I.e. engines and used equipment.
       The commenter also showed their agreement for the
  $l,000/kw  figure by stating that the $l,000/kw is the price
  seen today, and that the cost of I.e. engines will increase to
  $1,200 to  $l,500/kW when the economy improves.  It is true
  that the costs may change with the change in economic factors,

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   however,  the purpose of this analysis was to acquire a
   reasonable estimate of cost and then determine the nationwide
   impacts.   The effect of many factors on the operation and
   capital costs of control equipment cannot be predicted
   especially considering the schedule and resources available to
   the EPA.   These factors include distance from transmission
   lines,  availability of water resources,  and permitting issues.
                  Two cominenters (IV-D-21,  IV-D-33)  suggested
   that the cost analysis be revised to incorporate the role of
   energy recovery.
        Response;   In response to these and other comments
   indicating that the likely use of energy recovery should be
   incorporated in the nationwide impacts and analysis, the
   nationwide impacts were revised to include a more detailed
   review of energy recovery prior to promulgation of the final
   NSPS and EG.  See section 2.8.3,  Cost-Benefit Analysis, for a
   detailed discussion of the revised analysis.
        Comment ;   One commenter (IV-L-7)  objected to the EPA's
   decision to delete the 138 most profitable landfills from the
   nationwide impacts.  The commenter (IV-L-7)  contended that
   there is no basis on which to exclude the data on the best
   (most productive)  landfills in a way that hurts the
   cost/benefit analysis of such regulatory measures.  The
   commenter (IV-L-7)  noted that information given in the
   memoranda,  "Changes to the Municipal Solid Waste Landfills
   Nationwide Impacts Program Since Proposal, "  April 28, 1993,
   (Docket No.  A-88-09,  Item No.  IV-M-3)  and "Landfill Rule
   Energy Recovery Cost Analysis," December 16, 1992, (Docket
   No.  A-88-09, Item No.  IV-M-2)  indicated that many sites will
   not  install energy recovery equipment in absence of these
   rules; and that new landfill rules in California have caused
   many sites to install energy recovery equipment in order to
   comply with the new rule.   The commenter (IV-L-7) stated that
   these rules will force the development of new technologies and
   landfill gas recovery vendor services that will transform the
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  market, which will decrease up front installation costs and
  increase efficiency.
       Response;  The EPA agrees with the commenter that the
  landfill gas market will be transformed by new rules forcing
  the development of new technologies and landfill gas recovery
  vendor services.  This was a main reason the least cost
                                                  • x
  analysis option was developed; in order for the standard to
  "take credit11 for the positive changes to the landfill gas
  market and the increased use of energy recovery technology
  which the standard will generate.  There are several
  site-specific reasons that influence the choice of whether to
  recover energy:  financial limitations  (there is a large
  initial investment), ability to sell the energy, the risk
  factor (it is difficult to predict the productivity of a
  landfill), etc.  The standard should influence these factors
  and make it favorable for landfill owners or operators to
  choose energy recovery.  However, there are landfills that
  have energy recovery systems and some future landfills that
  will potentially have energy recovery systems in the absence
  of this standard.  The adjustment of deleting the 138
  landfills was made so as not to "take credit" for those
  landfills that would recover energy from landfill gas without
  the influence of this standard.  The 138 landfills estimated
  to install control in the absence of the standard is based on
  past numbers of landfills installing energy recovery and
  projecting into the future.  More information may be found in
  the memorandum "Landfill Rule Energy Recovery Cost Analysis,"
  December 16, 1992  (Docket No. A-88-09, Item No. IV-M-2).
       As this commenter has stated, when the NSPS and EG go
  into affect it is  likely that more landfills will choose
  energy recovery which will have an affect on the market and
  the up front installation costs.  However, the nationwide
  impacts are correctly based on current information.  The CAA
  requires periodic  reviews of NSPS.  Advances in energy
  recovery may be considered in the periodic reviews of this
  NSPS.

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2.8.2  Secondary Air Impacts
     Comment;  One commenter  (IV-D-20) suggested that the EPA
has not thoroughly assessed secondary air pollutant emissions
impacts from open flares.  The commenter questioned whether
open flare control devices are BDT and stated that the
proposal BID contains little  information on secondary air
                                                 • \
pollutant emissions from open flares.  The commenter
recommended that enclosed flares be chosen as BDT if further
evaluation demonstrates that  open flares have higher levels of
         •
secondary air emissions than  enclosed flares.
     Another commenter  (IV-D-17) recommended that the
occurrence of PICs from open  flares be addressed (references
to combustion data were included).  The commenter stated that
PCDD might be produced by combustion of NMOC, and suggested
that the occurrence or lack of occurrence of PCDD must be
addressed before combustion can be classified as BDT.
     The commenter (IV-D-17)  indicated that flare combustion
analysis should be required and should incorporate the percent
of chlorine in LFG, flare operating conditions  (i.e.,
temperature, residence time,  POHC, PIC (PCDD/PCDF, etc.), and
risk assessment.  For risk assessment, the commenter indicated
that the normalized distribution for an emissions source of
1 gram/sec with a dilution factor of 1 to 10 km should be
supplied.
     Response;  Open flares have already been established as
an appropriate control technology under section 111.  Open
flares are suitable for LFG if they meet the provisions under
40 CFR 60.18,  as discussed under section 2.6.3.  The EPA knows
of no data that indicates that open flares have higher
secondary emissions than other combustion devices.
     The EPA has already determined under previous projects
that flares operated according to section 40 CFR 60.18 will
achieve greater than 98 percent organics destruction.  The
available data considered by the EPA, while indicating the
presence of PCDD precursors in landfill gas, does not indicate
PCDD precursors after combustion in flares.

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       Comment;  One commenter  (IV-D-50) said that the proposed
  regulation appears to underestimate secondary emissions from
  LFG combustion, and challenged the assumption that
  LFG-generated electricity would likely replace coal-fired
  generation.  The commenter cautioned that previous EPA studies
  showed that energy recovery systems can result in a more
                                                   * *
  expensive and less efficient  source of energy due to higher
  secondary air emissions from  energy recovery systems fueled
  with LFG and reduced thermal  efficiency compared to natural
           *
  gas-fired generation.
       Response;  The EPA assumes that market forces govern the
  purchase of LFG-generated electricity.  The proposal BID
  discussion of secondary impacts assumed that a utility
  purchasing LFG-generated electricity would replace the most
  expensive electricity being purchased, which, at that time was
  usually coal-fired, not natural gas-fired, generation.  Since
  coal-fired generation is more costly and has greater secondary
  air impacts than LFG generation, LFG-generated electricity
  would reduce secondary air impacts from electricity
  generation.  The EPA reviewed the references provided by the
  commenter, but found no data  included specific to LFG.  It
  must be noted that no quantitative adjustment to the secondary
  air impact tables in chapter  6.0 of the proposal BID was made.
  The EPA made only a qualitative judgment about secondary air
  impacts of LFG-versus coal-generated electricity.  Information
  on LFG-generated electricity  programs and the estimated
  impacts of the LFG-versus coal-generated electricity is
  presented in the memorandum "Analysis on Landfill Gas
  Utilization  of the Soon-to-be Promulgated Clean Air Act
  Regulations  for Municipal Solid Waste Landfills"  (Docket
  No. A-88-09, Item No. IV-B-5).
       Comment;  One commenter  (IV-D-19) noted that turbines,
  boilers, and I.e. engines tend to have much higher NOX
  emissions than flares.  In addition, I.e. engines have higher
  CO emissions, while boilers and turbines have lower CO
  emissions than flares.

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        Response;   The goal of the regulation is to reduce the
   amount of LFG emitted to the atmosphere.   If a State has
   specific concerns regarding NOX or CO,  they may implement
   additional or more stringent regulations  to address these
   concerns.
        The EPA data does indicate greater NOX emissions from
   turbines, boilers, and I.e. engines than  flares.  However,
   this fact may be offset by the fact that  these devices can
   recover energy from LFG.  Energy recovery will have benefits
   of conserving the nation's supply of nonrenewable energy
   resources and will decrease pollution from the energy
   generation displaced by the use of these  devices.  These
   benefits are discussed in chapter 6 of the proposal BID, as
   well as in the proposal preamble (56 FR 24498; May 30, 1991).
   2.8.3  Cost-Benefit Analysis
        Comment;   One commenter (IV-F-6)  questioned whether the
   costs of the regulation are equal to the  health improvements.
   The commenter claimed that there has been no analysis of
   potential benefits of the regulation and  that only the
   threshold levels and control options have been considered in
   the rulemaking.   Another commenter (IV-D-39)  asserted that
   sufficient justification for the standards has not been
   provided on the basis of cost effectiveness and environmental
   benefits.   A third commenter (IV-F-3)  said that the data used
   in the RIA concerning the cost effectiveness and environmental
   benefits of the regulation were incomplete.
        Response;   Section lll(b)  of the CAA addresses categories
   of sources which cause,  or contribute significantly to air
   pollution,  which may reasonably be anticipated to endanger
   public health or welfare.   The NSPS are technology-based,
   rather than risk-based,  standards.   As  stated in the preamble
   under this NSPS,  MSW landfill emissions must be controlled to
   the level achievable by BDT,  considering  costs and any nonair
   quality health  and environmental impacts  and energy
   requirements.   The NSPS are not primarily concerned with
   quantifying health improvements,  as are NESHAP.

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       As explained in the preamble, the BDT was selected based
  on consideration of the costs and emissions reduction achieved
  by the regulatory alternatives as provided in section lll(b)
  of the CAA.
       Comment;  One commenter  (IV-D-36) stressed that the high
  costs incurred from addressing the small percentage of methane
  emissions derived from MSW landfills were not justified.
  Another commenter (IV-D-11) indicated that public utilities
  should excuse methane generated fuel cell power from
  least-cost regulations because of the social benefits gained
  from this clean fuel source.
       Response:  The selection of the NSPS and EG was not
  determined by the cost of methane reduction.  Methane
  reduction was considered as an ancillary benefit.  Nationwide
  annualized costs were estimated for new and existing MSW
  landfills to be approximately $4 and $90 million,
  respectively.  The average cost effectiveness of the NSPS  and
  EG are $1,200 per Mg of NMOC emission reduction.   The
  incremental cost effectiveness of going from a 150 Mg/yr
  emission rate cutoff to a 50 Mg/yr cutoff is $2,900/Mg for new
  landfills and $3,300/Mg for existing landfills.  The standards
  address MSW landfill emissions in a cost effective manner.
       The EPA is investigating fuel cells; however, the
  investigation is not complete to incorporate at this time.
  Additionally, the decision to require public utilities to  deal
  with fuel-cell generated methane in a prescribed manner is
  beyond section 111 Authority.
       Comment;  One commenter  (IV-D-50) noted that the proposal
  BID lacks correct information regarding costs of energy
  recovery systems because it does not include discussion of a
  backup flare system and system availability and reliability.
       Response;  The cost impacts of these regulations were
  calculated based on the use of flares and on the use of least
  cost devices  (including energy recovery).  Although the EPA is
  aware that many operators do maintain backup flares on site,
  they are not required in the NSPS and EG.  Operators may

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   determine on a site-specific basis whether to install a back-
   up device.  In many cases control devices may be reliable
   enough that a back-up is not needed,  especially considering
   that the NSPS emission standards do not apply during periods
   of malfunction.  Additionally,  when a backup flare is
   installed, it would likely last indefinitely and contribute
   relatively little to the overall cost of compliance with the
   standard.
        In regard to system availability and reliability, the
   proposal BID did not attempt to provide exhaustive information
   regarding energy recovery systems,  specifically because of the
   site-specific nature of factors influencing energy recovery
   selection decisions.  The proposal BID and subsequent analyses
   reasonably represent energy recovery system costs, however
   these costs are greatly affected by site-specific factors,
   which are best addressed by the MSW landfill owner or operator
   when the use of energy recovery is considered.
   2.9  MONITORING AND TESTING
   2.9.1  Monitoring
        Comment;  One commenter (IV-L-1)  recommended that the
   NSPS require the measurement of landfill gas emissions from
   collection systems and/or control devices on a real time basis
   using continuous emissions monitoring instrumentation rather
   than annually performing manual measurements such as
   Method 25C.
        Response:   In selecting measurement methods for measuring
   LFG emissions,  the EPA selected methods that were simple, yet
   would provide information adequate for establishing
   compliance.   Other methods may  be used if they have been
   approved by the Administrator.
        The final rule also requires surface emission monitoring
   of landfills on a quarterly basis to confirm correct system
   operation.  Surface emission monitoring will ensure that
   landfill gas control systems are operating adequately and that
   no significant emissions are escaping from the landfill
   surface.   For control devices,  continuous monitoring of

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  operating parameters is required.  The EPA will not require
  continuous emissions monitoring instrumentation when other
  less expensive methods are available that are appropriate for
  establishing compliance.
       Comment;  Two commenters  (IV-D-27, IV-D-39) asserted that
  the requirement to monitor residence time during.the initial
  performance test cannot be met, because residence times for
  control devices can only be calculated and cannot be
  monitored.
       Response;  The compliance provisions of the final NSPS
  (§ 60.755) are based on typical section 111 provisions for
  open flares and enclosed combustion devices.  The intent of
  this section of the regulation is to require that residence
  time be determined during the initial performance test for
  enclosed combustion devices.  The final regulation was changed
  to reflect that residence time should be determined in
  conjunction with gas flow measurements and temperature rather
  than "monitored."  After the initial performance test, the
  NSPS only requires that temperature be recorded with equipment
  calibrated, maintained, and operated according to the
  manufacturer's specifications.  Flow to the control device
  must be monitored, or else bypass line flow can be monitored
  or bypass lines can be sealed to prevent bypass.
       Comment;  Two industry commenters (IV-D-27, IV-D-39)
  recommended that monitoring temperature not be limited to
  Celsius units of measure, since most devices are provided with
  Fahrenheit units.
       Response;  Current policy is to use metric units in
  reporting; however, this does not preclude measuring in
  English units.  The following equation can be used for
  converting degrees Fahrenheit to degrees Celsius:
  °C -  (°F - 32)/1.8.
       Comment:  One industry commenter  (IV-D-27) suggested that
  the provisions for monitoring temperature at enclosed flares
  be changed to require monitoring "at least every 15 minutes"
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   rather than "every 15 minutes" to increase flexibility in how
   this requirement is met.
        One commenter (IV-D-39)  asserted that requiring a flow
   indicator that provides a record of gas flow at intervals of
   every 15 minutes is an unnecessary and expensive method to
   collect the required data.   The commenter recommended that
                                                   • %
   this requirement be replaced with the requirement that the
   owner or operator simply record flow at 15 minute intervals,
   which would allow for other methods of obtaining the data
   without requiring a specific type of equipment.
        Response;  The provisions for monitoring temperature of
   an enclosed combustion device have been revised.  The final
   provisions require a temperature monitoring device equipped
   with a continuous recorder and having an accuracy of
   ± 1 percent of the temperature being measured expressed in.
   degrees Celsius or + 0.5°C whichever is greater.  Records must
   be made at least every 15 minutes.  Also, the requirement of
   using a flow indicator that provides a record of gas flow at
   intervals of every 15 minutes has been changed to requiring a
   gas flow measuring device that provides a measurement of gas
   flow to, or bypass of, the control device.  If gas flow is
   monitored,  the gas flow rate must be recorded at least every
   15 minutes.   Alternatively,  a bypass system that has either a
   car-seal, lock and key,  or other device that reveals if the
   bypass system has been used can be installed instead of
   monitoring flow.
        Comment:  Two commenters (IV-D-26 and IV-F-6,  IV-D-27)
   recommended that the flare flame rather than the pilot flame
   be monitored to verify that the flare is operating at all
   times.  One of the commenters (IV-F-6)  stated that MSW
   landfills that have flares typically use intermittent pilots
   to conserve propane.   The commenter stated that continuous
   pilots are costly,  inefficient,  and unsafe.   One of the
   commenters (IV-D-27)  opposed the stringent provisions for
   monitoring flow to the flare or other control device,
   reporting that such equipment could cost from $4,000 to

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  $12,000.  The commenter proposed that a monthly measure of
  flow at the flare using various devices (e.g., pitot tube,
  orifice plate, etc.), along with continuous flame temperature
  monitoring, would be sufficient to catch any major changes in
  flow.
       Response;  The monitoring provisions of S 60*756 were
  revised to allow for continuous monitoring of flow to the
  flare pilot flame or the flare flame itself.  An intermittent
  pilot would not meet this requirement because it could not be
  continuously monitored.  If direct monitoring of the flare
  flame is not feasible because the temperature of the flare
  flame is too high and will cause the thermocouple of the
  monitoring device to burn out more quickly than if the pilot
  is monitored, the source may chose to monitor the pilot flame.
  The requirement to monitor flow to the flare or other control
  device at least every 15 minutes was intended to ensure that
  the collected landfill gas is being conveyed to a flare, or
  other suitable control device, rather than being discharged to
  the atmosphere.  The regulation has been changed since
  proposal to allow the alternatives of monitoring flow in each
  bypass line, or sealing bypass lines with car-seals or lock
  and key configurations that prevent bypass and reveal whether
  bypass has occurred.  This will allow flexibility and reduce
  costs.  Other comments and responses pertaining to open flames
  are contained in 2.8.2 of this chapter.
  2.9.2  Nitrogen Monitoring
       Comment:  Many commenters  (IV-D-7, IV-D-26 and IV-F-6,
  IV-D-27,  IV-D-35, IV-D-39, IV-D-55, IV-F-4, IV-L-5) contended
  that the 1 percent N2 limit in the proposed standard is
  unrealistic,  and that levels of 11  (IV-D-35), 12  (IV-D-27),
  20 to 25  (IV-D-26 and IV-F-6) and no less than 6 percent
   (IV-D-39) are more appropriate.  One commenter  (IV-D-39) also
  reported that successful operation has been shown at levels as
  high as 20 percent.  Three of the commenters  (IV-D-7, IV-D-25
  and IV-F-4, IV-D-34) recommended dropping the N2  limit
  altogether.   Two commenters  (IV-D-25 and IV-F-4,  IV-D-34)

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   stated that the requirement restricts operators in maximizing
   vacuum levels.  One commenter (IV-D-7) stated that setting the
   limit based on combustibility had no engineering basis.
   Another commenter (IV-D-39) also asserted that the 2 percent
   N2 limit in the collection header is too stringent.
        Several commenters (IV-D-26, IV-D-35, IV-D-39, IV-D-55)
                                                   •»
   discussed the N2 content of landfills.  The commenters stated
   that N2 levels of 7 to 8 percent (IV-D-35), 5 percent
   (IV-D-39, IV-D-55)  and between 1 and 4 percent (IV-D-26) are
            •
   common.  One commenter (IV-D-55) stated that Figure 3-3 of the
   proposal BID indicates that the N2 content of landfills levels
   out at 5 percent.  Another commenter (IV-D-39) referenced a
   document by EMCON Associates,  "Methane Generation and Recovery
   from Landfills", as the source for the 5 percent N2 level.
   The commenter also reported that the EMCON Associates document
   states that N2 is expected to peak just after placement of
   refuse, and will then fall dramatically as the refuse begins
   to decay to the 5-percent steady state level.  The commenters
   stated that the N2  content was due to trapped air buried at
   the time of filling the landfill (IV-D-26) and/or is released
   from the refuse (IV-D-39).  Another commenter (IV-D-3)
   suggested that it would be difficult to determine if the N2
   came from buried nitrogen or improper sampling.
        One commenter  (IV-D-39)  suggested the EPA develop a
   method to calculate NMOC corrected to a standard value of N2
   if the EPA is concerned that excessive air intrusion will
   cause a false measurement of NMOC in the LFG.  The commenter
   (IV-D-39)  asserted  that this N2  is released from the refuse
   and is not a result of air intrusion.
        Another commenter (IV-F-6)  suggested that well
   temperature and percent methane, should be used as the
   infiltration indicator,  instead  of difficult and expensive N2
   measurement techniques.
        One of the commenters (IV-D-27)  approved of the 1 percent
   N2 limit in Method  2E while performing gas generation rate
   testing,  but said that 12  percent is more appropriate for

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  operating gas collection systems.  The commenter noted that  it
  is only above 12 percent that methanogenic bacteria become
  dormant.  Another commenter  (IV-D-39) asserted that a small
  amount of air intrusion  (less than 3 percent) does not
  significantly reduce methane quality, nor does it cause
  subsurface fires.
       One commenter  (IV-D-29) suggested that the regulation
  allow landfill operators a choice between portable 02 monitors
  or Method 3C in order to detect  infiltration in the header
  system.  "The commenter reported  experience using portable 02
  monitors and noted  that they give instantaneous readings,
  whereas Method 3C often requires laboratory testing.  In
  addition, the commenter requested that either 02 or N2 be
  allowed for use in  the detection of header system leaks.  The
  commenter suggested that the requirement be revised to a
  maximum of 3.5 percent 02 content in the header system, based
  on experience with  LFG containing an 02 content between 0.5
  and 3.5 percent without any adverse problems.
       Two commenters (IV-D-30, IV-D-39) stated that there are
  simpler methods for leak detection.  Another commenter
   (IV-D-27) suggested that the EPA establish alternative methods
  for monitoring air  intrusion because N2 testing is so
  expensive.   The commenter reported costs of $150 per well per
  month.  The commenter recommended a number of options for
  determining air infiltration, including:   (1) deviations
  around a stabilized air N2 level,  (2) deviations  (10° C)
  around a stabilized temperature  at the wellhead, and
   (3) surface-integrated measurement.
       Response;  In  Method 2E as  well as daily operation, the
  N2 concentration in the extracted LFG is important because  it
  indicates whether the maximum vacuum achievable without air
  infiltration  is being obtained from the landfill.  The N2
  limit is provided as a safety measure to avoid fires and
  explosions that may result from  pulling too much air into the
  landfill, and to avoid altering  the anaerobic state of the
  landfill.  For compliance purposes, the main concern is that

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   the system is pulling at maximum capacity up to the point of
   infiltration.  The 1 percent value was based on previous
   comments received from industry, which were misunderstood in
   establishing 1 percent as a limit, when in reality, the
   sources were using the 1 percent as a target.  The reason N£
   concentration was being restricted at proposal instead of (>2
                                                   •»
   is that the portable ©2 meters were unable to measure ©2 to
   the low levels necessary, and that 02 may be consumed and not
   detected.
        The monitoring provisions of the final NSPS have been
   revised after consideration of the comments.  The N2 limit
   during operation of the collection system at the wellhead has
   been increased to a level less than or equal to 20 percent as
   determined by Method 3C.  Because the N2 concentration limit
   was raised,  it is now also feasible for sources to monitor 02
   to indicate the maximum vacuum achievable without air
   infiltration.  Therefore, a provision allowing for an 02 limit
   of 5 percent as indicated by an oxygen meter calibrated
   according to Method 3A of Appendix A of 40 CFR 60 has been
   added to the final rules.  In addition, a provision has been
   added to require the operation of the collection system with a
   landfill gas temperature of less than 55 °C (or the maximum
   established value)  demonstrated under § 60.753(c).  The final
   provisions require monthly monitoring of these parameters.
        The N2  limit in Method 2E has also been increased to
   20 percent.   If a sample is found to contain more than
   20 percent N2 in Method 25C,  then that sample should be
   removed from the collection.   The equation for calculating the
   concentration of NMOC in Method 25C has also been revised to
   correct the NMOC concentration in the LFG sample to zero
   percent N2•
        As mentioned above, a provision has been added to the
   final rule requiring the temperature to be maintained at less
   than 55° (or higher site-specific established value) at each
   well.   If  the LFG temperature at the wellhead increases above
   the temperature threshold,  the new provisions require an

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  adjustment of the vacuum to reduce the temperature.  The value
  of 55° C was cited by industry experts as an alert temperature
  that may indicate a problem.  Since temperature variability
  exists between landfills and between wells within a landfill,
  the provisions to establish higher operating temperatures at
  individual wells has been added.  A higher temperature limit
  will be allowed if the owner or operator can demonstrate with
  supporting data that the higher temperatures do not cause
  fires or adversely affect the anaerobic decomposition of the
  waste.
       Comment:  One commenter  (IV-D-26) contended that
  maintaining an 02 level in a flowing LFG stream below
  1 percent is unreasonable, unnecessary and also not cost
  effective.  The commenter asserted that more sensitive and
  accurate well adjustments are made from temperature, percent
  methane, amount of vacuum, and flow volume.  The commenter
  stated that intruded 02 would be stripped off by the landfill,
  and that temperature and percent methane would be immediately
  affected by both intruded air and direct leaks into the
  system.
       The commenter further recommended that no 02 limitations
  for individual wells be set, and that an O2 level of 8 percent
  in the main header would be appropriate.
       Response;  The EPA is assuming that this commenter was
  referring to N2 instead of ©2  (see above response) or that the
  commenter was commenting from a previous version that
  discussed air intrusion testing, which differs from the
  proposed regulation.  The commenter did not provide details
  concerning how temperature, percent methane, amount of vacuum,
  and flow volume could be used to determine appropriate
  adjustments.  The proposed regulations required monitoring of
  N2 to control air intrusion.  Changes to the final regulation
  addressing air intrusion were discussed in the response to the
  previous comment.
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   2.10 MODELING
        C7TM?ntl;  Two commenters (IV-D-30,  IV-D-39)  stated that
   the use of the first-order gas rate generation model in
   Method 2E was not backed up by evidence  which shows it to be
   more accurate than other available models.   The commenters
   asserted that this discourages the development of more
   accurate models,  and cited the modeling  discussed" in the
   December 1989 ASCE Environmental Engineering Journal as
   examples of models under development.
        Three commenters (IV-D-46,  IV-D-49, IV-F-4)  argued that
   the EPA LFG emission models overestimate the effects and
   amount of LFG produced,  resulting in the installation of
   control systems that are larger than necessary.  The
   commenters suggested using methods and technology currently in
   practice at landfills.
        One commenter (IV-D-55)  argued that the EPA has no data
   to support the use of their model equation.   The commenter
   asserted that the model  equation is based on the premise that
   the LFG generation rate  is solely a function of age and the
   amount of refuse.  The commenter stated  that LFG generation
   rates are highly  dependent upon fluctuating  moisture content
   of the refuse,  and,  therefore,  there is  no such thing as a
   "gas generation rate constant" that only needs to be
   calculated once.   The commenter further  argued that the NMOC
   emissions mechanism is not described by  the  Scholl Canyon
   model, and encouraged the elimination of the use of
   mathematical formulas for applicability  of controls.
        Another commenter (IV-D-45)  stated  that because of the
   health effects of NMOC,  testing should be performed to
   determine NMOC emission  rates rather than relying on estimates
   of NMOC emissions.
        Another commenter (IV-D-17)  stated  that the final results
   of the model,  although based on sophisticated formulae,  may be
   inaccurate because of the quality of background data.
        Response;  Although the EPA acknowledges that other
   models may be in  use or  under development, the Scholl  Canyon

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  based model used within these regulations was chosen because
  it  is both simplistic and adequate for purposes of estimating
  LFG emissions.  The model was submitted to industry for review
  at  frequent intervals throughout  its development  (see
  Docket A-88-09 subcategory  II-C for Agency submittals and
  subcategory II-O for industry and vendor responses).  The EPA
  considers it adequate and effective for purposes  of these
  standards.  Actual landfill gas emissions data were collected
  and compared to emissions estimates using the model.  The
  actual emissions and the modeled  estimates correlated
  satisfactorily (see Docket  A-88-09, Item No. IV-A-l).
       In the interim between proposal and promulgation of the
  regulation the EPA obtained site-specific gas generation data
  characterizing landfill emissions from both arid  and moist
  regions of the United States.  The data were applied to the
  input data bases proportionally,  to account for the effect of
  moisture on gas generation.  This data and the methodology
  used to assign it to the input data bases is described in the
  memorandum "Methodology Used to Revise the Model  Inputs in the
  Municipal Solid Waste Landfills Input Data Bases" (Docket No
  A-88-09, Item No. IV-M-4).
       While the model is used to select the regulatory cutoff,
  the NSPS allows site-specific data to be used to  improve the
  resulting NMOC emission rate upon which the applicability of
  controls depends.  As commenter IV-D-55 noted, the Scholl
  Canyon model does not describe NMOC emission mechanisms;
  rather it describes methane generation.  In the tier system,
  if  the Tier 1 NMOC emissions estimates are above  the
  regulatory cutoff, the owner or operator may elect to sample
  for a site-specific NMOC concentration to improve the NMOC
  emission rate estimation.   If the resulting NMOC  emission rate
  is  still above the regulatory cutoff, the owner or operator
  may also perform gas flow testing to obtain a site-specific k,
  for use in the emission rate calculation.
       These options improve  the applicability of the model to
  the individual landfill.  The gas flow testing, if performed,

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   can also be used to determine a site-specific area of
   influence for use in determining system design.   (See
   section 2.12, "Design Specifications," for discussion of
   system design.)
        The EPA understands that the tier default values have
   been misused (e.g., emission inventories,  control system
                                                   •»
   design, etc.).   The default values should only be used for
   applicability of the regulations.  They were selected to be
   used as a screening tool to determine applicability of the
            *
   control requirements of the regulations.  They should not be
   used to estimate emissions for inventories or control
   equipment design.
        Comment: One commenter (IV-D-32) discussed various
   aspects of the equations used in calculating the NMOC emission
   rate using default information in S 60.753 of the proposed
   regulation.   The commenter stated that the proposal BID and
   regulation did not clearly describe how the values M and R
   were derived, and recommended either the BID be made
   consistent with  the regulation or the definition for R and M
   exclude discussion of nondegradable waste.  In addition, the
   commenter requested that the variable C^QC/ which is defined
   differently in two equations, be used in a clear and
   consistent manner.  The commenter noted that the equation in
   §  60.753(a)(1)(ii) of the proposed regulation differs from the
   equation on page 9-6 of the proposal BID in that the time
   since closure (c) does not always equal zero and e~ck does not
   always equal one.
        The commenter reported that the regulation does not
   clearly state what value should be used for the NMOC
   concentration, and that S 60.753(a)(2) refers to the
   calculated emission rate of NMOC,  not to the NMOC
   concentration.   The commenter also suggested that it is
   unclear whether  the annual emissions rate is determined using
   the 8,000 ppmv default value for NMOC concentration or using
   the site-specific value calculated via S 60.753(a)(3)  along
   with the site-specific k value.   Lastly, the commenter

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  requested clarification of how frequently the NMOC
  concentration should be revised.
       Response:  The definition of CNMOC is the same in all
  equations.  "As hexane" was inadvertently left off one of the
  definitions, and has been corrected in the final regulation.
  The equation in § 60.753(a)(1)(ii) of the proposed NSPS is for
  new landfills opening after May 31, 1991.  It was assumed that
  new landfills will not be closed by promulgation of this
  regulation, in which case e"*0 is equal to one.  However, this
  section is referred to by the EG in S 60.34c, which may
  require calculation of an NMOC emission rate after landfill
  closure.  Therefore, the equations in S 60.754(a)(1) of the
  renumbered final NSPS have been changed to include the closure
  term e~*c.  The use of default or site-specific values, when
  calculating the NMOC emission rate, depends on what tier the
  owner or operator is in at the time.  The Tier system should
  be viewed as a step system with Tier 1 being the first step.
  A diagram of the entire tier system was provided in figure 1,
  Overall Three-Tiered Approach for Determination of Control
  Requirements, in the proposal preamble.  Section 60.754(a)(1)
  of the final renumbered NSPS specifies that 4,000 ppmv as
  hexane be used for calculating the mass emission rate of NMOC
   (MNMOC)•  Paragraph (a)(2) correctly refers to the calculated
  MNMOC when comparing it to the 50 Mg/yr standard.  This
  process is referred to as Tier 1, where default values are
  used to calculate MNMOC and then compared to 50 Mg/yr.  Tier  2
  incorporates a site specific NMOC concentration and is
  described in S 60.754(a)(3).  Tier 2 would only be used if the
  MNMQC as calculated in Tier 1 is greater than  50 Mg/yr.  If
  the MNMOC calculated in Tier 2 is greater than 50 Mg/yr, the
  owner or operator can elect to install controls or use Tier  3,
  which is described in S 60.754(a)(4).  Section 60.754(a)(4)
  has been revised to specify that both the site-specific NMOC
  concentration and site-specific methane generation constant
   (k) be used in Tier 3.
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        Tier 2 requires that a site-specific NMOC concentration
   be determined from a number of surface locations at a
   landfill.  Many commenters stated that the statistical
   approach to calculate the number of samples and sampling
   frequency is not supportable.  In an effort to address the
   comments, the required number and location of the sampling
                                                   • %
   probes were revised.  A landfill performing Tier 2 is required
   to take two samples per hectare of surface area, up to
   50 samples.  Because the confidence level calculation was
            *
   removed, the site-specific NMOC concentration is required to
   be recalculated every five years.  The ten year recalculation
   period option has also been removed.
        Because of the lower NMOC emission rate stringency level
   of 50 Mg/yr and the fewer number of landfills affected by the
   regulations due to the 2.5 million Mg maximum capacity
   exemption level, a single tier 2 recalculation period of every
   5 years is considered justified and not overly burdensome.
   The lower stringency level makes it more likely that a
   landfill's NMOC emission rate could increase such that it
   significantly exceeds the 50 Mg/yr stringency level during a
   10 year period.
        Additional guidance has been incorporated into the final
   regulation in § 60.754(a)  for determining values for M^ (mass
   of refuse in the itn section, Mg) and R (average annual refuse
   acceptance rate, Mg/yr).   As specified in chapter 9 of the
   proposal BID, the mass of the nondegradable refuse should be
   subtracted from the total mass of refuse in a particular
   section of the landfill or from the refuse acceptance rate to
   avoid overestimating the LFG emission rate.
        Comment;  One conunenter (IV-D-25)  suggested using
   site-specific kinetic coefficients in Tier 3, instead of site
   specific emission rates.   The commenter gave information on
   how the kinetic coefficients would be estimated.
        Response:  The purpose of Tier 3 is to determine a site-
   specific methane generation rate constant (k).   The k value is
   determined from a site-specific emission determined by

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  extracting LFG from a portion of the landfill  (i.e.,
  installing gas extraction wells) .
                 one industry commenter  (IV-D-27 and IV-F-5)
  noted that a conversion factor used in the calculation of the
  default concentration of NMOC fails to account for the final
  product needing to be given  "as hexane."  The conunenters
  concluded that this resulted in a default value nearly five
  times greater than the values upon which it was based, and
  requested that the default value be recalculated.  The
           •
  conunenters also contended that the mass emission rate of NMOC
  would be affected by the "as hexane" error.  The commenter
  found the different conversion factors provided in the
  proposed regulation and BID  to be overly confusing, and
  recommended an alternative conversion factor, providing the
  calculations upon which it was based.
       Response:  The problem  with the conversion factor noted
  by the commenter is actually a problem within the section of
  the regulation where the NMOC concentration from Method 25C is
  used to calculate the NMOC emission rate.  This error occurred
  as an oversight in the typing of the proposed regulation,
  which should have included additional text in the proposed
  NSPS.
       The appropriate text has been added to S 60. 754 (a) (3) to
  ^indicate that the NMOC concentration from Method 25C must be
  divided by 6 to convert from NMOC concentration as carbon to a
  concentration in terms of hexane.  The conversion of NMOC
  concentration from as carbon to as hexane was performed
  correctly in the analysis upon which the selection of the
  regulatory emission rate cutoff was based.
  2.11 TEST METHODS
       Comment t  One commenter (IV-D-10) expressed concern that
  the proposed test Methods 25C, 3C and 2E contain procedures
  that can be both laborious and costly.  The commenter
  suggested that the regulations include provisions that do not
  limit owners or operators to only these three methods if other
  equivalent methods exist or  may be developed.  The commenter

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   stated that this will reduce costs and allow a field sampling
   technique they are developing to test methane and NMOC
   emission rates that will be less expensive and more accurate
   than current methods.
        Response;  Owners and operators may propose alternative
   methods, provided they are approved by the appropriate
   reviewing agency.
        CoftHnept;  One commenter (IV-D-54)  suggested that the
   nomenclature be changed from NMOC to TGNMO in proposed test
   Method 25C because the technique for analyzing NMOC is
   substantially similar to the technique for TGNMO.  The
   commenter stated that it would be less confusing for the
   nomenclature to remain TGNMO for the technique.
        Response;  The EPA has defined CNJJOC and NMOC within the
   methods according to the purposes for which the methods were
   developed.   Since the surrogate for the designated pollutant
   in these regulations is NMOC,  Method 25C,  which was developed
   to support these regulations,  references NMOC.
   2.11.1  Nonmethane Organic Compound Sampling and Analysis
        Comment;  One commenter (IV-D-19)  requested that
   alternatives other than Method 25C (for example, meters,  SUMMA
   canisters as in the EPA method TO-14,  and total hydrocarbons,
   and total nonmethane hydrocarbon analyzers)  be allowed in the
   regulations for the sampling and measurement of LFG.   Another
   commenter (IV-D-3)  suggested that EPA Method 18 and
   Method 8240 be used in place of Method 25,  because Method 25
   is more expensive.   The commenter also stated that Method 25
   does not allow for chemical-specific data,  would not indicate
   any contaminants at significant toxic levels,  and does not
   meet the criteria set forth in RCRA guidelines SW-846.  The
   commenter further indicated that the sampling depth in
   Method 25 is too shallow and,  therefore,  yields no
   representative NMOC concentrations.
        One commenter (IV-D-32)  recommended that test Method 25C,
   used for collecting and analyzing NMOC concentrations from
   probes and referenced to in §  60.753(a)(3),  be incorporated

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  into the regulation by reference.  The commenter was, however,
  concerned about the use of a sampling requirement that may
  create up to 50 holes through the cover of the landfill every
  5 to 10 years.  The commenter suggested that language be
  included in the regulation or test method to decommission the
  sampling wells to maintain the integrity of final^cover.
  Also, another commenter (IV-D-55) stated that penetrations of
  the landfill cover to install additional wells or for sampling
  provide avenues of escape for the toxic compounds.  The
  commenter recommended that the approval of mitigation measures
  be required pri r to cover penetration.
       One commenter (IV-D-39) asserted that the use of
  Method 25C for determining NMOC concentrations is questionable
  because:   (1) probe samples and gas extraction well samples do
  not typically agree with each other,  (2) probes only give a
  static measurement of NMOC under the cap, and  (3) probe
  samples are not representative of the heterogeneous nature of
  landfill wastes.  The commenter recommended that a number of
  methods should be allowed, including Method 25C, as well the
  collection of bag samples from a larger area of the landfill
  at the surface, and sampling wells sunk completely through the
  trash that could later be used in the collection process.
       One commenter (IV-D-26) stated that operators of multiple
  landfill sites should be allowed to statistically determine
  average NMOC concentrations throughout the landfill system,
  rather than on a landfill-by-landfill basis.  The commenter
  argued that for a gas analysis to be truly representative of
  what is in the landfill, gas needed to be collected within the
  trash and not beneath the cap.
       Another commenter  (IV-D-55) asserted that due to the
  uneven distribution of pools of  leachate  (the  source of most
  NMOC emissions), the use of concentration samples from only
  five probes can lead to extremely misleading conclusions.
       One industry commenter  (IV-D-27) supported the
  requirements for determining NMOC concentration with an
  80-percent confidence, but requested  that composite sampling

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   be allowed on the additional sampling (maximum 50),  arguing
   that the average concentration is all that is finally used.
   The commenter noted that this would greatly reduce the cost of
   such sampling and analysis.   This commenter also suggested
   that an alternative be allowed to installing probes.
        One commenter (IV-F-6)  claimed that the 80 percent
   confidence interval in Method 25C is being compared to the
   variation between the samples.  The commenter asserted that
   since the. focus is on the difference between the 5 sample
   averages and the 8,000 ppmv, there is no reason to take more
   samples when the difference  between them is large.
        Two commenters (IV-D-30,  IV-F-3)  stated that the
   80 percent confidence level  for NMOC sampling is not based on
   sound logic since there is no proof that the distribution of
   LFG is normally distributed  as is the t-statistic on which the
   confidence level is based.
        One commenter (IV-D-39) asserted that no data are
   presented to show that the student t-test is a valid procedure
   for analyzing data collected from LFG sampling.  The commenter
   argued that other environmental monitoring programs such as
   groundwater monitoring data  have shown that the student t-test
   is not a valid test in most  cases and that the EPA has
   previously allowed more appropriate alternative statistical
   analyses.   The commenter suggested that a specific statistical
   test not be required,  but rather that an appropriate
   statistical method be used.
        Response;    When specifying a method for demonstrating
   compliance,  the EPA seeks to select a method that is as simple
   as possible but provides information adequate for establishing
   compliance.   Method 25C was  developed for this rule  because it
   measures total nonmethane organics,  which is the surrogate
   specified within these regulations for the designated
   pollutant.   Methods that do  not separate methane from the
   other organic compounds,  such as Method 21,  are not  readily
   amenable for measuring NMOC  in LFG.   Methods TO-14  and 8240
   are not appropriate alternatives to Method 25C, for  the

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  following reasons.  Method TO-14 is more expensive than
  Method 25C and analyzes specific compounds rather than simply
  NMOC.  Method 8240 is a GC/MS analytical procedure for a
  predetermined list of compounds and could not be used
  effectively for measuring NMOC concentration.
       Based on the comments received, the EPA decided to
  specifically allow the use of Method 18 or Method 25 for
  determination of reduction efficiency.  If Method 18 is used
  it must be speciated at a minimum for the compounds listed in
  the most recent version of AP-42.  While the EPA believes
  Method 18 may be more costly to implement than Method 25, it
  does not doubt the adequacy of either method for determining
  reduction efficiency.  However, other test methods may be used
  for any of the specified methods if they are approved by the
  appropriate reviewing agency.  Although other methods may be
  used, if properly validated, usually only one or two
  established EPA methods are specified because they have been
  demonstrated to provide valid results and because the
  comparative results from several sources reporting to one
  agency are more meaningful when the same analytical method has
  been used.
       A requirement has been added to the regulation to refill
  the probe holes with cover material once sampling has taken
  place.  The owner or operator may choose to  leave the probe  in
  place and simply plug the sampling probe or  remove the probe
  and refill the hole with cover material.
       The NMOC sampling requirements of tier  2 in the final
  regulation have been revised.  Many commenters stated that the
  statistical approach to calculate the number of samples and
  sampling frequency is not supportable.  In an effort to
  address many of the comments, the required number and location
  of the samples were revised.  A landfill performing the tier 2
  sampling to obtain a site-specific NMOC concentration is
  required to take two samples per hectare of  surface area up to
  50 samples.  A landfill owner or operator may take more than
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   50 samples,  but all the samples must be included in the
   calculation to obtain the average NMOC concentration.
        Due to the large variation in NMOC concentration  from
   landfill to landfill, using average NMOC concentrations from
   multiple landfill systems would not provide a reasonable basis
   for installing collection and control systems at individual
                                                   • *
   landfills.   The EPA considers that when the regulatory cutoff
   is exceeded and NMOC sampling is performed, the site-specific
   NMOC concentration should be the basis for applicability, not
           •
   an average  concentration based on multiple landfills.
   Additionally,  a multiple landfill average might result in
   control applied to fewer landfills.   Instead of landfills
   emitting greater than 50 Mg NMOC/yr being controlled while
   others emitting less than 50 Mg NMOC/yr are not, the use of a
   multiple-landfill average NMOC concentration might exempt all
   of the landfills in the system.   The NMOC sampling is  meant to
   improve the accuracy of the estimate for landfills near the
   regulatory  cutoff,  to determine if the specific landfill
   warrants control.
        The sample probe depth requirement has been changed to
   read sunk "at  least" 3 feet below the cover material or cap to
   give some flexibility in sampling.
        Composite sampling can be allowed only if each individual
   sample is of equal volume.   This is to insure that the
   resulting NMOC concentration is equal to the value that would
   be obtained if an average value from concentrations of
   multiple samples were used.
   2.11.2  Method 2E
        Comment;   Many commenters (IV-D-25,  IV-D-30,  IV-D-31,
   IV-D-34,  IV-D-39, IV-D-47,  IV-F-4)  questioned the accuracy and
   validity of Method 2E.   One commenter (IV-D-30)  argued that
   Method 2E is based on questionable engineering assumptions,
   and limited testing of a volume of the landfill that is
   unknown at  a single point in time,  since the true region
   influenced  by  the extraction well is unknown.   The commenter
   maintained  that the EPA did not provide documentation  to

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  confirm the accuracy of the proposed test method.  Two
  commenters (IV-D-25, IV-D-34) stated that Method 2E either
  overestimates or underestimates well-spacing requirements,
  depending on landfill characteristics.  While another
  commenter (IV-D-46) stated that the treatment systems will be
  overdesigned and inappropriate for small and medium size
                                                  • *
  landfills.  One commenter (IV-F-4) stated that Method 2E may
  overestimate well spacing by two to three times.
       Another commenter  (IV-D-31) stated that active extraction
           *
  testing using Method 2E lacks accuracy, is too involved, and
  is too costly to be the basis for design or the decision to
  install collection systems.  The commenter claimed that the
  extraction well depth should not extend to 75 percent of the
  landfill depth, except in small landfills, due to the expense
  of wells deeper than 30.5 to 36.5 meters.  The commenter
  recommended that perimeter wells could catch gas escaping from
  deep wells.
       Several commenters (IV-D-25, IV-D-27, IV-D-30, IV-D-31,
  IV-D-34) were concerned about the cost of Method 2E.  Two
  commenters (IV-D-25, IV-D-31) noted that in the case of small
  landfills, the cost of performing Method 2E could exceed the
  cost of an adequate control system.  Two commenters  (IV-D-25,
  IV-D-34) argued that using Method 2E to determine well spacing
  would increase costs because wells would be spaced too close
  together, due to fluctuations in barometric pressure.
       Response:  The EPA developed Method 2E with input from
  industry representatives.  Industry provided experience on
  techniques that the EPA then developed into Method 2E.  Since
                                            •
  these techniques are used by industry representatives, the EPA
  is confident that Method 2E can be used effectively to
  estimate the area of influence.  The final regulations,
  however, no longer require a specific determination of the
  area of influence, so sources that are not comfortable with
  Method 2E are not required to use it.
       Method 2E was also developed to be used to determine a
  site-specific methane generation rate constant  (k),  for use  in

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   Tier 3 of the applicability determination.   Method 2E,  as a
   method of determination of k,  is based on the Scholl Canyon
   model and the area affected by a given well (ROI), as
   determined by testing.   Since  the site-specific k value would
   replace the default k value, the EPA is confident that a
   site-specific k value determined by Method 2E would better
   represent an individual landfill than the default k value.  It
   should be noted here that use  of the Tier system is also
   optional, and sources not comfortable with the use of
   Method 2E could document the sufficiency of another method, or
   install controls.
        Since the EPA removed the prescriptive requirements for
   collection system from the final regulations,  and replaced
   them with design criteria, the concerns expressed by
   commenters over these issues should be alleviated.
        The cost of performing Method 2E was taken into account
   when the tier default values were selected.  Default values
   were selected in an attempt to minimize the number of
   landfills that would perform Tier 3 and then not be required
   to install controls.   In other words,  the default values were
   selected in an effort such that landfills that were estimated
   to emit more than 50 Mg/yr by  Tiers 1 and 2 and therefore
   elected to perform Tier 3 would still likely need to install
   controls, thereby making use of the wells already installed
   for Tier 3.  This is also a factor landfill owners and
   operators will need to take into account when deciding whether
   to advance to Tier 3 or to install controls after Tier 1 or
   Tier 2.  The EPA acknowledges  that landfill owners and
   operators will base how far to advance in the tier system on
   site-specific factors,  including cost.
        The EPA also increased the maximum capacity exception
   level to 2.5 million Mg.   This exemption will exempt
   approximately 90 percent of all landfills from the
   requirements of the regulations.
        Comment;   Several  commenters (IV-D-25, IV-D-30,  IV-D-31,
   IV-D-34,  IV-D-51)  were  concerned about the  impact of

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  barometric fluctuations on the accuracy of Method 2E.  One
  commenter  (IV-D-31) reported that, in his experience, pressure
  differences are very slight and these differences can be
  overwhelmed by barometric fluctuations.  The commenter
  suggested placing pressure probes closer to the well, at 3,
  7.6, and 15.2 m, and plotting the pressure differentials
                                                  • *
  versus the natural logarithm of distance to extrapolate to get
  the distance at zero pressure difference.  The commenter
  contended that the correction for barometric pressure does not
  take into account time lags for the landfill pressure to
  equilibrate to barometric swings.  The commenter maintained
  that extracting two void volumes does not assure that "new
  gas" is being collected or that gas is being extracted at the
  same rate it is being generated.  The commenter recommended
  that steady state pressure distributions should be achieved
  first, meaning that pressures are rising or declining at a
  steady gas extraction rate.
       Another commenter  (IV-D-51) suggested that better methods
  for determining the area of influence for a given well  (other
  than Method 2E) included continuous recordings of probe and
  atmospheric pressure or spreading out the time frame for spot
  monitoring performed at the same time each day.
       Response:  In Method 2E, pressure readings are taken,
  and, as in the case of all pressure readings, these pressure
  readings are measured as a pressure differential.  In this
  case, it is the difference in pressure between the atmosphere
   (barometric pressure) and the landfill.  In Method 2E, the
  pressure differential is corrected for barometric pressure to
  determine the landfill pressure.  It is irrelevant that the
  correction of barometric pressure does not take into account
  the time lag between barometric pressure changes and landfill
  pressure changes, because in Method 2E the concern is with the
  relative difference in  landfill pressure from probe to probe
  at a given moment in time.
       The barometric fluctuations may affect the landfill gas
  generation rate; however, the landfill gas generation rate is

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   being determined over a period of time where varying
   barometric pressures impact the gas generation rate and these
   effects are being averaged together.   Since the extraction
   wells must function during all barometric conditions,  any
   conditions in which Method 2E is performed are conditions that
   are more or less likely to occur and are applicable to the
   landfill.
        After review and consideration of comments,  the EPA has
   revised Method 2E to allow the use of a semi-logarithmic plot
   of pressure differentials versus distance from the wellhead
   for determining ROI.
        Method 2E is being kept in the regulation as an
   alternative means for establishing applicability, as a part of
   the tier system.  In Tier 3, an owner or operator has the
   option to perform Method 2E to develop a site specific gas
   generation rate constant for use in estimating the NMOC
   emission rate.   There may be other methods that would estimate
   the site specific gas generation rate constant more
   accurately,  but these would entail more cost and more testing
   time.   The EPA is confident that Method 2E sufficiently
   estimates the site specific gas generation rate constant.
   However, this method does not have to be used.   An owner or
   operator can install controls after Tier 2 and not perform
   Tier 3 (Method 2E),  or the owner or operator can propose
   another method for estimating the gas generation rate
   constant.
        When Method 2E is used as a means for estimating the area
   of influence,  the EPA does not believe that either continuous
   recording or prolonged monitoring will improve the accuracy of
   the area of influence estimate significantly.   Method 2E
   already requires that barometric pressure measurements be
   taken at the same time as the probe pressure readings.   Also,
   Method 2E requires that the pressure measurements be taken
   every 8 hours  over several days or more,  which would mean that
   pressure measurements are taken at the same time each day.
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       Comment:  One conunenter  (IV-D-31) stated that  single
  wells are preferred over the  cluster wells regardless of
  whether the history of the site  is known, because at sites
  where the history is known generation rates varied  by factors
  of 1.5 to 3.
       Response:  A landfill owner or operator has the option to
  choose between using three cluster wells or five wells spaced
  evenly over the landfill.  The regulation does not  require the
  use of cluster wells for Method  2E testing.  In fact, cluster
           «
  wells should not be used if the  composition of the  refuse, age
  of the refuse, and the landfill  depth of the test area cannot
  be determined.  Where these factors can, however, be
  determined, cluster wells are appropriate.  Therefore,
  landfill operators have two options for siting wells in
  Method 2E testing, when the required data is available.
       Comment:  Three commenters  (IV-D-27, IV-D-31,  IV-D-39)
  were concerned with the depth of perforation of the well due
  to the possibility of air infiltration.  One conunenter
  (IV-D-27) suggested that a perforation depth should start no
  closer to the surface than 6.1 m, while the second  conunenter
  (IV-D-31) suggested that only the bottom one-third  of the well
  be perforated.  The second commenter  (IV-D-31) pointed out
  that less perforations would  result in a smaller radii of
  influence.  The third commenter  (IV-D-39) asserted  that a
  2/3 perforated section was appropriate for wells deeper than
  13.7 m, but  for shallower wells  a solid section should be no
  less than 4.6 m, unless a synthetic liner is being  used.  The
  commenter asserted that the specific design standards  in the
  proposal be  replaced with a performance standard that  can be
  met by qualified professional designers, who can design an
  optimal gas  recovery system.
       Response:  These commenters have raised a valid concern
  regarding well perforations too  close to the surface.
  Accordingly, the provisions in S 60.759 have been revised to
  provide only criteria for designing collection systems, rather
  than prescriptive specifications.

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        Comment;   One commenter (IV-D-27)  opposed the use of
   Method 2E to calculate maximum expected gas generation rate in
   S 60.757(b)(1)(i)  of the proposed regulation.   The commenter
   argued that using Method 2E here is in conflict with the
   calculation equation provided in S 60.754 of the proposed
   regulation which allows, but does not require, aerate to be
   determined through Method 2E.
        Response:   Sections l through 4 of Method 2E do not apply
   to a controlled landfill.  In addition, the final regulations
   have been revised at S 60.758(b)(l)  to allow the owner or
   operator to calculate the maximum expected gas generation flow
   rate according  to S 60.755(a)(1)  or any other method to
   determine maximum flow rate,  as long as the method is approved
   by the Administrator.
        Comment;   One commenter (IV-D-39)  discussed the
   requirement of  using a blower with a flow rate of 8.5 m3/min.
   The commenter stated that a larger or smaller blower may be
   needed, depending on site conditions.
        Response;   The blower capacity requirement of 8.5 m3/min
   is the estimated minimum capacity requirement for performing
   Method 2E.  As  the commenter pointed out, depending on the
   flow rate conditions at each particular site,  a larger blower
   capacity may be required.  Therefore, the language in
   Method 2E has been revised to indicate a blower capacity
   requirement of  at least 8.5 m3/min.
   2.11.3  Method  3C
        Comment;   One commenter (IV-D-27)  suggested that only one
   calibration standard is necessary for calibrating the thermal
   conductivity detector because of its linear scale.
        Response;   The requirement for three calibrations is
   included in Method 3C because it was previously determined to
   be appropriate  during the development of Method 3.  Requiring
   three calibrations enhances the statistical validity of the
   calibration test,  and the EPA does not consider the three
   tests overly burdensome.
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  2.12 DESIGN SPECIFICATIONS
       Cprnm^nt ?  one commentef  (IV-D-46) alleged that the
  proposed regulations may encourage untrained "landfill gas
  engineer consultants" to offer their services to city
  administrators.  Two commenters  (IV-D-25, IV-D-34) were
  concerned that Method 2E is very complex and will be used by
                                                  • %
  inexperienced gas system designers which will affect the
  integrity of the results.
       Response:  In determining whether to hire a consultant,
           •
  landfill owners and operators should obtain information on the
  previous experience and qualifications of the consultant and
  on their professional memberships and certifications.  The
  landfill industry, professional organizations, and State air
  pollution control agencies may be able to provide city
  administrators with information about reputable landfill gas
  engineering consultants.  In response to commenters' concerns,
  the final regulations indicate that the gas collection system
  design plans must be prepared by a professional engineer.
  Also, it should be noted that use of Method 2E is optional and
  might not be used at many landfills, so there should not be a
  shortage of experienced contractors.
       Comment;  Two commenters  (IV-D-30, IV-D-36) contended
  that the collection and control design criteria used by the
  EPA is based on scientifically unproven and, therefore,
  invalid models and tests.  One commenter  (IV-D-30) mentioned
  that various California regulatory agencies had based their
  standards on actual emission measurements and not on models.
  Two commenters  (IV-D-46, IV-D-49) said that the recommended
  gas treatment systems are overdesigned for smaller landfills
  and that the models used overestimate the amount of LFG
  produced.
       Response;  The gas generation model and the technical
  basis for gas collection system design were reviewed by
  industry frequently during their development and all comments
  submitted by industry were considered  (see Docket No. A-88-09,
  Items II-c-ll, II-C-22 and ll-c-24; and Item Nos. II-D-38 to

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   II-D-43,  II-D-47 to II-D-50 and II-D-52 to II-D-54).   The EPA
   considers the model reasonable for these regulations  and is
   currently using the model in a number of other studies as
   well.
        As stated in an earlier response,  the Tier default values
   should only be used for determining applicability of  the
   regulations.  They were selected to be used as a screening
   tool to determine applicability of the control requirements of
   the regulations and should not be used to estimate emissions
   for inventories or control equipment design.
        Comment:  One industry commenter (IV-D-27) argued that
   the equation for determining gas mover sizing incorrectly
   sizes for the peak flow rate over the life of the landfill and
   not the maximum LFG flow rate expected over the life  of the
   gas moving equipment.   This commenter pointed out that gas
   movers can be upgraded or downgraded as the LFG moving needs
   change.
        Two commenters (IV-D-39,  IV-F-6)  questioned the
   relationship between maximum expected flow rate and gas
   collection equipment life.  The commenters stated that
   equipment life should not have an effect on gas flow  rates and
   should not be factored into the value of t.
        One commenter (IV-D-39)  requested clarification  on
   whether a gas collection system needs to be designed  to handle
   the maximum expected gas flow rate from the onset or  if the
   system can be designed in phases as the landfill is developed.
   The commenter recommended that phased design and installation
   be allowed.
        Response;  The EPA agrees that upgrading and downgrading
   equipment should be allowed,  and the definition of the
   parameter t has been changed to reflect the time frame the
   owner or operator intends to use the equipment, instead of the
   equipment life.   The new definition states that t is  equal to
   the active life of the landfill or the age of the landfill
   plus the  time the owner or operator intends to use the
   equipment,  whichever is less.   Equipment can now be sized for

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  the maximum LFG flow rate expected over the use of the
  equipment and not over the life of the equipment.
       The equation containing the parameter t in $ 60.755
  calculates the maximum LFG flow rate for the period of time
  the equipment is being used.  The parameter t is defined as
  the oldest active age of the landfill while a given piece of
  equipment is being used.  For a landfill that will close
  before the completion of the intended equipment use period, t
  is the total active life of the landfill.  For a collection
           *
  system that the intended equipment use period will be up
  before landfill closure, t is the age of the landfill when the
  equipment will be taken out of service or the age of the
  landfill plus the intended time of equipment use.  For
  equipment that will be used after closure only, t is the age
  of the landfill when the equipment is installed.
  2.12.1  Collection System Design
       Comment;  Many commenters  (IV-D-7, IV-D-9, IV-D-27 and
  IV-F-5, IV-D-36, IV-D-38, IV-D-49, IV-D-52, IV-D-56, IV-F-4)
  wanted more flexibility to be incorporated into the design
  standards.  The commenters asserted that these designs should
  be more site-specific and determined by the designers and
  owners.  Many of these commenters requested that the
  regulation allow landfills operated and designed based on the
  SCAQMD regulation to be considered equivalent to a landfill
  designed and operated under these regulations.  One industry
  commenter  (IV-D-27) urged the EPA to provide less restrictive
  specifications for well construction and system components,
  adding that many effective systems have been used that would
  not meet these specifications.
       Another commenter  (IV-D-37) conceded that the regulation
  includes a mechanism for flexibility through alternative
  design plan submittal to the Administrator or the designated
  reviewing agency, but requested that the EPA further encourage
  States to allow such flexibility.  Two commenters  (IV-D-52,
  IV-F-4) stated that the proposed regulation does not take  into
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   consideration alternative methods of LFG control in use at
   existing MSW landfills.
        Two conunenters (IV-D-25,  IV-D-34)  noted that although the
   proposed NSPS allows for the submittal  of an alternative
   design,  the NSPS and EG require that the collection and
   control  system be designed in conformance with chapter 9 of
   the BIO, where the design specifications are far too rigid.
   Because  of this rigidity, the commenter stated that systems
   meeting  the SCAQMD standard would not meet the alternative
            «
   design criteria in the proposed standard.
        Another industry commenter (IV-D-27) argued that the
   collection system design specifications in the NSPS should be
   moved to the proposal BID and used solely as guidance, rather
   than as  a design specification.   The commenter noted that
   industry experts would submit site-specific designs to the
   State agencies for approval,  and that this would foster
   creativity and the development of innovative systems.
        Response;  After consideration of  the comments,  the EPA
   agrees that the specific design criteria in the proposed rule
   may be overly restrictive and not the most appropriate design
   for all  landfills.   The design specifications in the proposed
   rule may be useful in designing active  vertical collection
   systems.  However,  because of the many  site-specific factors
   involved with landfill gas collection system design,
   alternative systems may be necessary.   Therefore,  the
   prescriptive specifications have been removed and S 60.759 has
   been revised to present more general design criteria for
   active collection systems.   This will allow flexibility and
   allow, or even encourage, alternative designs.   The final
   standards require all owners or operators to submit design
   plans to the State agency for review.   The design plans must
   demonstrate that the criteria in S 60.759 are met or that the
   design is a sufficient alternative,  and must be signed by a
   registered professional  engineer.   These provisions allow for
   use of a wide variety of system designs.   Designs could
   include  vertical wells,  combination horizontal and vertical

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  collection systems, or horizontal trenches only, leachate
  collection components, and passive systems.  Any design can be
  used as long as an adequate design plan is submitted and
  approved.
       Additionally, landfill owners or operators can use
  section lll(h)(3) of the CAA to request approval of gas
                                                  • %
  collection systems that provide equivalent control, but do not
  comply with either the specifications in the regulation, or
  with the plan  development and review requirements.
           *
         The final EG for collection systems references the
  NSPS.  For EG  based on sources of health-related pollutants,
  States are required to submit plans for EPA approval that
  provide emission limitations at least as stringent as the
  NSPS.  An owner or operator of a system designed for the
  SCAQMD standard would need to demonstrate that  it effectively
  addresses the  design criteria in §S 60.752(b)(2) and 60.759.
       The final EG has been revised as follows to clarify that
  State plans must require installation of collection and
  control systems that are equivalent to those required in the
  NSPS:
       11... meeting the conditions provided in
       S 60.752(b)(2)(ii) of this part."
       Comment;  Two commenters  (IV-D-25, IV-D-34) recommended
  that the regulations incorporate an alternative collection
  system design  provision, which would establish  a performance
  standard based on the SCAQMD rule.  The SCAQMD  rule uses
  integrated surface sampling of TOC to determine the need for
  additional gas control.  This would allow more  flexibility  for
  the gas collection designs.  One commenter  (IV-D-37) noted
  that their State regulation requires that gas collection
  systems be designed so that surface concentrations of TOC
  measured as methane do not occur at levels above 1,000 ppmv or
  along the gas  transfer path.  The commenter asserted that the
  surface test encourages system maintenance.  A  fourth
  commenter  (IV-D-55) also recommended that a surface emission
  standard be established which landfill operators must
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   maintain,  thereby allowing maximum design flexibility and
   encouraging more cost effective innovations.
        Another commenter (IV-F-6) maintained that production
   tests should not be required for gas collection system design
   because they are inaccurate, and that they should be replaced
   with the use of operating criteria.  The commenter advised
   that all mandatory design features should be  removed from the
   provisions and that all designs should be produced by
   certified professional engineers instead.
           *
        Response:  The final NSPS allows for collection system
   design based on either the criteria provided  in § 60.759 of
   the NSPS or an alternative design,  provided that the
   alternative meets the requirements in § 60.752(b)(2)(ii) and
   is submitted for review.   The final NSPS differs from the
   proposed regulation in that it no longer provides prescriptive
   design specifications.
        One commenter was concerned about the integrity of the
   landfill cover and that cracks in the cover could allow
   emissions to the atmosphere even when an effective collection
   system has been installed.  As mentioned in the proposal
   preamble and by commenter IV-D-26,  surface emission monitoring
   as used in the SCAQMD seems appropriate for determining that
   closer well spacing is in fact needed.   As mentioned in the
   proposal preamble, the EPA was already considering what role
   the California test might reasonably fill in  these regulations
   (see 56 FR 24492-24493).
        The EPA considers surface emission monitoring to be an
   appropriate tool for monitoring both cover integrity and the
   effectiveness of well spacing.  Therefore, some aspects of the
   surface emission monitoring test have been incorporated in the
   new § 60.753,  where all of the operational provisions for the
   collection system have been brought together.
        After initial installation of the collection system,
   owners and operators will be required to operate the
   collection system with a  methane concentration less than
   500 ppm at all points around the perimeter of the collection

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  area and across the surface of the collection area following a
  serpentine pattern spaced 30 meters apart.
       Compliance with this operational standard is to be
  demonstrated by monitoring surface concentrations on a
  quarterly basis using an organic vapor analyzer, flame
  ionization detector, or other portable hydrocarbon monitor.
                                                  • %
  For closed landfills, if three successive quarterly monitoring
  periods fail to indicate any methane concentrations of 500 ppm
  or greater, then the owner or operator may skip to an annual
           *
  monitoring frequency.
       If an instrument reading of 500 ppm or greater is
  produced, the location of the exceedance must be recorded, and
  cover maintenance or adjustment to the vacuum at adjacent
  wellheads must be made within 10 days.  The 10-day schedule
  was selected to allow the personnel to continue monitoring
  without stopping to make adjustments, but to assure that
  conditions at the locale of the exceedance are attended to
  quickly.
       The location of the exceedance must be remonitored within
  10 days.  If a second exceedance is recorded at the same
  location, additional adjustments shall be attempted and
  remonitoring performed within 10 days.  Any location that
  exceeds the 500 ppm reading 3 times within a quarterly period
  must install a well or other collection device within 120 days
  of the first exceedance.
       The methane concentration level of 500 ppm was chosen
  based on data received from numerous sources, including:
   (1) information provided by the SCAQMD stating that this was
  an appropriate level and the level used at landfills in that
  district;  (2) information indicating that some leak detection
  programs for other industries currently use 500 ppm and
  analyzers are capable of detecting this level;
   (3) instrumentation specifications citing this as an
  appropriate number and that familiarity with this level is
  broad; and  (4) site visits conducted by the EPA indicating
  that 500 ppm is an acceptable detection level.

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        Comment;   One commenter (IV-D-20)  stated that S 60.758(b)
   in the proposed regulation should be stated more clearly,
   suggesting it follow the description given in the summary.
        Another commenter (IV-D-29)  stated that the preamble
   explains that the pressure at the wellhead should be negative
   pressure to collect the gas adequately,  but that the
   regulation does not give this detail.   The commenter suggested
   that this be added to the regulation.
        Response;   The final NSPS does not present design
   specifications for a specific gas collection system, but
   includes design criteria that the EPA believes provides a
   level of detail and clarity necessary to allow owners and
   operators to design collection wells meeting BDT.
        The final NSPS requires that pressure in the gas
   collection header be monitored on a monthly basis in
   S 60.756(a).  Section 60.755(a)(3)  requires that negative
   pressure be maintained, or an additional well be added to  the
   system,  except in certain specified situations.
        Comment;   One commenter (IV-F-6)  noted that the system
   designs  and diagrams in the preamble failed to provide for
   either expansion joints or pipe sloping for drainage.
        Three commenters (IV-D-20,  IV-D-22,  IV-D-55) contended
   that settlement of the refuse mass after extraction well and
   header line installation is not taken into consideration in
   § 60.758(b)(2)  of the proposed regulation.   One commenter
   (IV-D-55)  recommended that the regulation require that swing
   joints,  slip lines, or other acceptable devices that will
   allow the collection system to move with the landfill without
   the collection system breaking be installed.  One commenter
   (IV-D-20)  suggested that the majority of header piping be
   buried underground in severe winter areas,  and suggested that
   provisions be  added for routine investigations of buried
   lateral  lines  that may become fractured.   Another commenter
   (IV-D-22)  questioned the effects  of settlement of extraction
   wells which are 30 m on-center through  impermeable caps.
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       One commenter  (IV-D-20) warned that gas extraction wells
  should usually be located as close to the base of the landfill
  as can be achieved to prevent problems associated with low
  vertical refuse permeability.  The commenter further
  recommended that, in the case of landfills with leachate
  collection systems, the extraction well should terminate at
  approximately 3 m above the leachate collection system.
       Response;  The EPA agrees with the commenters concerns
  regarding settlement.  The figures and diagrams provided in
  the preamble to the proposed regulations were intended to
  illustrate basic system components, and were not intended to
  be exhaustive.  Because the final regulations require all
  design plans to be submitted to the Administrator for
  approval, but do not provide specific designs for gas
  collection systems, the use of slip lines, swing joints or
  other devices, and the location and specific length of header
  pipes, is neither required nor precluded by the final NSPS and
  EG.  The use of these devices can be determined during the
  site-specific design.
       The EPA considers this level of flexibility appropriate
  for the regulation and believes that operators or owners will
  choose the appropriate placement for their site specific
  situation and include that in their design plans.  Also, if a
  State or a landfill owner/operator has a particular concern
  about pipe freezing or the well depth, they can address that
  in their specific design plan.
       Comment;  One commenter  (IV-D-32) suggested that
  provisions be added to the regulation requiring that the LFG
  collection system design be capable of controlling the
  off-site migration of subsurface LFG.
       Response;  The EPA considers collection and control
  systems designed to meet the criteria in § 60.759 of the final
  NSPS to be sufficient for the control of off-site migration.
  The pulling effect of the perimeter wells, which are sited to
  cover all areas of  the boundary, should prevent LFG from
  migrating off-site.  However, the commenter is correct;

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   collection and control systems need to address off-site
   migration.  A provision has been added to $ 60.752 requiring
   collection and control systems be designed to minimize
   off-site migration of subsurface LFG.
        In addition to requiring that migration be addressed in
   each collection system design plan that is submitted,  the
   final regulation includes a new S 60.753 on collection system
   operation.  This section compiles various operational
   provisions that had previously been located at different
   points throughout the proposed regulation into one section.   A
   requirement to operate the collection system with a surface
   methane concentration of less than 500 ppm, which is fulfilled
   through the use of a surface monitoring device, has also been
   included.
        The provisions for the surface monitoring include a
   requirement to monitor surface methane concentrations  around
   the perimeter of the collection area.   This will further
   ensure that offsite migration is controlled.   These provisions
   are applicable to all systems designed according to the
   provisions of §§ 60.752 and 60.759 and systems which include
   any alternatives to the provisions of  SS 60.753 through 60.758
   that have been submitted for review.
        Comment:  One commenter (IV-D-27)  suggested that  the
   bentonite seal around the collection wells and the probes
   should be placed at the cover/refuse boundary rather than 4 ft
   above the gravel pack.   The commenter  argued that this would
   reduce the chance of air intrusion.
        Another commenter (IV-D-39)  also  asserted that the
   proposed gas well design lacks a 1-ft  thick bentonite  seal
   immediately above the crushed stone and that the crushed stone
   has been found to be very important in preventing air
   intrusion into the well.   The commenter also stated that the
   diameter of the well boring should be  0.61 to 0.91 m,  which
   allows for the use of larger diameter  boring rigs, which are
   used to install a leachate extraction  well in the same bore
   hole as the gas well.

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       Response:  As a result of concerns such as those
  expressed by these commenters, the prescriptive design
  specifications for gas collection systems have been removed
  and replaced with criteria for the design of such systems.
  The design plans must meet the criteria in S 60.759 or
  demonstrate equivalence, be prepared by a professional
                                                  • *
  engineer, and approved by the Administrator  (i.e. the State or
  local agency that has been delegated authority).
       The proposed design specifications were established to
           *
  provide an owner or operator a clear design to follow in lieu
  of submittal of an independently-designed system.  However,
  since the regulation has been revised in S 60.759 to provide
  criteria for sufficient collection systems which allow sources
  to design collection systems in any manner they chose (as  long
  as the design plans are prepared by a professional engineer,
  and are approved by the Administrator), wells of any diameter
  may be bored, as long as the system is approved.
       Comment;  One commenter  (IV-L-1) recommended that the EPA
  require either a comparable collection efficiency for affected
  landfills of all sizes or, for landfills located in
  environments that prevent achieving the required numerical
  efficiency value, minimum equipment specifications for the
  collection system.  The commenter  (IV-L-1) suggested achieving
  this by:  restricting the lengths, type of materials and
  techniques used to assemble the well points, seals, pumps,
  compressors, dryers and collection systems; requiring minimum
  commitments of resources, expertise and levels of effort to be
  devoted to system maintenance; and further limiting the time,
  provided in the proposed NSPS, after initiation of active
  landfilling operations before which construction and operation
  of landfill gas collection and treatment systems must take
  place.
       Response;  These standards and emission guidelines are
  promulgated under section 111 of the CAA, which requires the
  standards be set based on the application of BDT considering
  costs and any nonair quality health and environmental impacts

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   and energy requirements,  at the time the standard is
   promulgated.   An NSPS establishes a nationwide minimum level
   of control,  but it is based on the application of BDT.
        The commenter's concern regarding the collection
   efficiency for affected landfills is a valid concern and has
   been addressed by the EPA.   The EPA considers surface emission
   monitoring to be an appropriate tool for monitoring both cover
   integrity and the effectiveness of well spacing and vacuum in
   order to ensure adequate collection efficiency.  Therefore,
            *
   surface emission monitoring has been incorporated in § 60.753,
   where all of the operational provisions for the collection
   system have been grouped together.
   2.12.2  Determination of Well-Spacing
        Comment;   One commenter (IV-D-26 and IV-F-6)  argued that
   less restrictive design and operating parameters for LFG
   control systems can be specified and yet still achieve the
   desired emissions reductions.   The commenter's particular
   concern is the design criteria for wellhead spacing.  The
   commenter contended that under normal conditions,  well head
   spacing for central wells of 90 to 120 m is sufficient to
   control surface emissions and lateral migration of LFG.  The
   commenter stated that at these distances a zone of negative
   pressure builds beneath the landfill cap and will keep LFG
   from escaping through the landfill cap.   The commenter
   contended that on occasion this spacing is inadequate due to
   subsurface factors that restrict the movement of LFG and the
   vacuum created by the wells.   The commenter asserted that in
   these areas,  surface methane readings above 50 ppm can be
   detected using surface measurements for methane.   The
   commenter agreed that closer well spacing is necessary where
   this is clearly demonstrated.
        Another commenter (IV-D-39)  stated that the proposed
   design specifications for well spacing assume that the
   landfilled waste is homogeneous.   The commenter noted that in
   reality this is not true because the waste composition varies.
   Because of the variable nature of the fill,  the commenter

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  supported a performance standard rather than a design
  standard, and recommended that alterative designs be allowed
  and encouraged.
       One commenter  (IV-D-30) questioned the use of ROI as
  determined by the Method 2E pumping test.  The commenter
  asserted that Method 2E is comprised of unnecessary "leak
  testing" which  is more expensive and takes longer than other
  methods.
       One commenter  (IV-D-26) contended that short term pumping
  tests  (for k calculation) do not yield accurate data and
  provide no basis for sizing LFG collection systems.  The
  commenter stated that uncontrolled landfills have built up
  landfill pressure and that initially, the test wells will show
  higher flow rates than at true steady state.  The commenter
  asserted that with  a full well field in place, 6 to 12 months
  is required to  reach steady state.  The commenter contended
  that no basic pump  test, including the EPA's proposal, is
  reliable and will invariably overestimate the quantity of gas
  generated.
       The commenter  (IV-D-26) stated that they have solved the
  pump test problem by designing gas extraction systems so that
  the blower compressor has the ability to produce a minimum  of
  13 to 25 cm of  water column vacuum at the most remote point in
  the header/lateral  system.  Friction loss is controlled by
  allowing only a 2.5 cm water column pressure drop per 30.5  m
  before pipe diameter is increased.  The commenter  (IV-D-26)
  stated that this allows the gas extraction system's ability to
  collect gas to  be the controlling factor, not a "guess" at  the
  landfill's ability  to produce gas.
       One commenter  (IV-D-26) contended that Method 2E assumes
  a uniform, isotropic, fully developed, concentric vacuum
  pattern around  the  well, however, this does not occur in
  actual practice.  The commenter stated that it is entirely
  predictable that a  50-acre landfill with an HDPE cap and 0.9 m
  final cover can be  covered by a single vertical gas well.
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        Another industry commenter (IV-D-27 and IV-F-5)  urged
   that greater flexibility be allowed in establishing the area
   of influence used for well-spacing.  The commenter (IV-D-27)
   suggested that engineering equations are just as effective for
   calculating the area of influence and are much less expensive.
   The commenter requested that engineering equations be allowed
   in lieu of Method 2E testing for establishing the* area of
   Influence.  Two commenters (IV-D-25, IV-D-34)  agreed that
   Method 2E is only one of several methods that can be used as a
   guide for* gas collection design.
        One commenter (IV-D-27)  faulted the three methods
   provided in the proposal/ noting that two of them are based on
   expensive field testing procedures, and that the third is
   based on theoretical modeling utilizing only two site-specific
   values.  The commenter suggested that experts in the field
   could better determine an effective area of influence.
        One commenter (IV-F-4)  faulted area-of-influence methods
   of determining the well spacing because these methods have
   been demonstrated primarily at large landfills and may be
   misleading or inappropriate for all sizes of landfills.  The
   commenters (IV-D-25,  IV-D-34)  also stated that Method 2E would
   result in an overly large area of influence in deep landfills,
   causing the system to miss as much as 85 percent of the LFG.
        One commenter (IV-D-26)  recommended that all references
   to radius of influence and Method 2E be deleted and be
   replaced with the general recommendation that the LFG
   extraction system be designed by a competent and qualified
   registered professional engineer and that such plans be
   submitted and approved by the local regulatory agency.
   Another commenter (IV-F-6)  stated that Method 2E is not
   necessary to determine the area of influence;  it is only
   necessary to determine if there is no gas in the perimeter
   monitoring probes and that there is less than 50 ppm methane
   in the surface emissions.
        Response;  In response to the many comments requesting a
   simpler approach for determining the area of influence for

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  purposes of collection system spacing, the EPA has removed the
  specific methods for determining ROI or any other area of
  influence determination from the requirements of the
  regulations.  Instead, as mentioned earlier, the final
  regulations require a professional engineer to prepare
  collection system design plans with gas collection systems of
                                                  • %
  sufficient density to achieve uniform control of surface gas
  emissions and address gas migration.
       Method 2E is no longer required, but can still be
           •
  performed to determine the appropriate area of influence for a
  given landfill.  Method 2E has been used before and generates
  useful data (see Docket No. A-88-09, Categories II-C and II-D
  and the response in section 2.11.2 for further discussion of
  the development of Method 2E).  The EPA developed Method 2E
  with input from industry representatives.  Industry provided
  experience on techniques that the EPA then developed into
  Method 2E.  The EPA believes that Method 2E can be used
  effectively to estimate the area of influence.
       As mentioned in previous responses, quarterly monitoring
  of the surface methane concentration has also been added to
  the rule to help ensure cover integrity and effectiveness of
  well spacing.
       Comment;  Three commenters  (IV-D-30, IV-D-39 and IV-F-3,
  IV-F-4) stated that the curves prescribed in the regulation
  for use in well spacing, which are based on landfill depth and
  blower vacuum, are not field-tested curves and will result in
  wells spaced too closely.  In addition, the commenter
   (IV-D-39) remarked that the graph entitled "Estimated radius
  of influence as a function of blower vacuum" needs to account
  for pressure drops associated with header losses in the
  piping.
       One commenter  (IV-D-26 and IV-F-6) stated that "radius of
   influence" is a relative term with little actual meaning,
  because the calculations are theoretical and have not been
  reliable for predicting actual flow conditions in the real
  world.  Another commenter  (IV-D-55) contended that a simple

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mathematical formula that can be used on all landfills for the
placement of collection wells does not exist.
      Another commenter (IV-D-7) suggested that the proposed
method of calculation for the spacing of gas wells and vacuum
contradict the commenters experience and should be revised.
The commenter claimed that wells have been spaced at much
                                                • *
greater distances within landfills with no air infiltration
and that well spacings of 46 to 76 m can be operated
successfully.  The commenter recommended that landfills be
         •
allowed to use greater well spacing if they can demonstrate
collection of 80 percent of the calculated or Method 2E
measured gas production.
     Response:  The EPA determined that the curves given in
the proposal regulation did not adequately address field
situations.  The curves were developed using theoretical
methods and did not have all of the many factors influencing
radius of influence factored into them.  The curves were
removed from the regulation.  The regulation no longer
specifies the method that must be used to determine the area
of influence for well spacing.
     The EPA determined that a performance based standard for
collection systems was not feasible to prescribe and enforce,
and that a collection system meeting the criteria in S 60.759
(or equivalent) represents BDT (See section 2.7).   Eighty
percent collection of the Method 2E measured gas production
would not be equivalent in all cases and is not a feasible
format for the standard.  The BDT for controlling LFG was
determined to be a well-designed collection system routed to a
control system achieving 98 percent reduction of NMOC.  A
landfill owner or operator can use any method they choose for
determining the sufficient density of their collection system,
as long as the system meets the criteria provided in S 60.759
and is submitted to the Administrator for review.   In
addition, surface emission monitoring provisions have been
incorporated into the final regulation to ensure adequate
collection of LFG.

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  2.13 OPERATIONAL STANDARDS
       Comment:  Three commenters  (IV-D-27, IV-D-39, IV-F-6)
  contended that the regulation was overly specific in requiring
  the use of an orifice meter to measure gas flow rate at the
  collection header, and argued that other devices, such as
  pitot tubes and texture flow tubes would be just as effective.
       Response:  The orifice meter referred to in the proposed
  regulation is just one device used to measure gas flow.  Other
  types of flow measurement devices may be used in its place.
           *
  Regardless of the type of meter used, the meter must be
  calibrated using the procedures outlined in section 4 of
  Method 2, appendix A to 40 CFR part 60.
       Comment;  One commenter  (IV-D-7) suggested that the
  process to be used for correcting for excess air intrusion
  around the well-head should be left to the discretion of the
  owner or operator.  The commenter further stated that the
  current language of the proposed regulations seems to
  discourage methods of adjustment  (increasing blower speed,
  repairing leaks, etc.) other than those in the proposal.
       A second commenter  (IV-D-29) warned that issues such as
  LFG leaks in equipment, air emission aspects of storage, and
  treatment of leachate and/or condensate were not addressed
  under the proposed regulation.  This commenter provided
  information on how their State addressed these issues.
  Another commenter  (IV-D-55) also pointed out that various
  additional operational criteria are needed, such as
  flame-outs, pipe leaks, landfill movement, air injection,
  sampling ports, etc.
       One commenter  (IV-D-55) recommended that the design
  standards require the installation of backup fuel supplies  to
  maintain minimum combustion temperatures and ensure proper
  combustion of the NMOC and toxic air contaminants.
       Response;  The final regulation has been revised to
  incorporate the suggested flexibility for correcting excess
  air intrusion.  Any method can be used to correct for excess
  air intrusion as long as it does not adversely affect the

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   integrity of the gas collection system,  or the ability or
   effectiveness of the gas collection system to collect landfill
   gas.
        The treatment of leachate and condensate is addressed
   under RCRA (subtitle D).  Landfill gas leaks in equipment and
   air emissions from storage were not part of the f^ocus of this
   NSPS.  It is assumed, however, that operable and well
   maintained equipment will be used which will reduce air
   emissions, through leaks  in equipment.
        Requirements for downtime caused  by equipment
   malfunction,  flame outs, pipe leaks, etc., have been added to
   the regulation (see section 2.14.2,  System Shutdown).   All
   combustion devices are required to pass a performance test
   and/or monitor parameters to ensure proper operation.   Some
   devices may need auxiliary fuel to meet these requirements and
   other devices may not.  The EPA considers these requirements
   to be adequate without mandating backup fuel.
        Comment;  One commenter (IV-D-27)  requested that the
   regulation should clearly discuss the  subject of pressure at
   the wellhead during start-up, since some systems do have
   positive pressure at the wellhead during the start-up phase.
        Another commenter (IV-D-55)  recommended the requirement
   to have negative wellhead pressure requirement be eliminated
   and a performance standard for all points on the surface of
   the landfill be established.   The commenter stated that LFG
   generation typically surges about 2  weeks after a rainfall
   which causes the pressures in the collection wells to be
   positive.   The commenter also stated that the negative
   pressure requirement limits the operations ability to shutdown
   part of the collector's  system (see  section 2.14.2,  "System
   Shutdown," for more detail on this comment).
        Another commenter (IV-D-39)  asserted that the requirement
   to have negative pressure at the gas collection wellhead
   cannot always be met because a well  may be overstressed or may
   be experiencing condensate problems, and,  therefore, may need
   to be cut back.   Also, the commenter stated that immediate

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  installation of an additional well is not always permissible
  under State law.  The conunenter recommended that a minimum
  90-day time period over which a well can be brought back into
  compliance be incorporated in order to satisfy the negative
  pressure requirement.  The commenter also recommended that,
  instead of requiring installation of a new well, that the
  regulations allow an owner or operator to restore a well's
  function, require the owner or operator to submit a plan to
  the State for correcting the function if not restorable, and
  to require the operator to comply with such a plan once it is
  approved by the State.
       One commenter  (IV-D-7) stated that the requirement to
  install an additional well if negative pressure cannot be
  achieved through valve adjustment at the wellhead is vague.  A
  second commenter (IV-D-27) suggested that a time schedule
  needed to be added to the provisions for installing additional
  wells when a negative pressure at all wells cannot be
  achieved.  The commenter said that in some States, a lengthy
  permit process is required before installing additional wells,
  and further noted that sometimes specific wells actually need
  to be removed from a system, although no reasons for such
  removal were provided.
       Response;  In the interim between proposal and
  promulgation, the EPA sought to improve the provisions of
  these regulations regarding both maintenance of negative
  pressure at the wellhead, and the addition or replacement of
  wells.  As mentioned in the previous response, any operational
  adjustments the operator can make to restore the well to
  proper function are not precluded by these regulations.
       After initial  installation of the collection system,
  owners and operators will be expanding the collection system
  over time to provide adequate coverage for all areas in which
  waste has been deposited for 2 years if the area will be
  closed or at final grade, or 5 years if the area is still
  active.  In the case of system expansion, the EPA assumes that
  landfill owners and operators will include these wells in

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   their overall management scheme,  including interaction with
   State authorities,  as necessary,  to allow timely installation.
   Given that these wells are added by design,  the NSPS requires
   that they be installed within 60 days of the waste reaching
   the specified age (2 years for closed areas,  5 years for
   active areas).   The 60 days were included, even though the
                                                   •»
   installation is likely planned and materials ought to be
   on-site,  to allow for potential delays due to weather or
   availability of drilling rigs,  which are often hired under
           •
   contract.
        The  final regulations now provide three exceptions to the
   requirement for negative pressure at each wellhead.   The first
   is the occurrence of fire or a significant increase in well
   temperature.  In this case, the owner or operator must report
   the positive pressure occurrence in the annual report.  The
   second exception is if the source uses a geomembrane or
   synthetic cover.  If a geomembrane or synthetic cover is used,
   the owner or operator must develop and include acceptable
   pressure  limits in the design plan.  The final exception is
   when a well is decommissioned to accommodate for declining gas
   flows. In this case the well may experience static positive
   pressure  after shutdown, as long as the changes made to the
   system are incorporated into the design plan and approved.
        There are two cases in which wells must be added that
   were not  included in the design plan:   when negative pressure
   cannot be restored at a given wellhead within 15 days
   (exceptions noted above),  and when surface methane levels of
   500 ppm or more have been recorded at a location 3 times
   within a  quarterly monitoring period.   In the first case,
   15 calendar days are allowed to restore negative pressure at
   the wellhead and thereby avoid installation of an additional
   well.   The principal reason positive pressure is likely to
   occur is  that the collection system capacity in the locale of
   the well  is less than the production in the locale.   Either
   capacity  can be increased through adjustments to the vacuum,
   or system expansion is warranted.   If adjustments are

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  adequate, the pressure recorded at the next required
  monitoring  (15 days) should be negative.  The 15 days allows
  time for a  surge in generation after significant rainfall to
  subside, as mentioned by commenter IV-D-55.  This also allows
  time to resolve the problems mentioned by commenter IV-D-39.
  If negative pressure cannot be restored within this 15-day
                                                  • %
  period, and the area is producing more gas than the system in
  that area is able to handle, then the installation of an
  additional  collection device within 120 days is warranted.
  Also, if rainfall results in increased generation on a regular
  basis, additional capacity is also warranted.
       In the case when methane concentrations are monitored at
  500 ppm or  more, two 10-day monitoring periods are allowed to
  reduce methane concentrations below 500 ppm.  There are two
  reasons likely to contribute to excessive methane levels:
  cover failure, or ineffective area of influence at the
  adjacent wells.  When excessive methane concentrations are
  recorded, 10 days are allowed for personnel to evaluate the
  problem.  If the cover has been disturbed, maintenance will
  likely reduce surface levels of methane.  On the other hand,
  if the area of influence is ineffective for the gas production
  level in the vicinity, adjustment of the vacuum may extend the
  effective area of influence, and cause methane concentrations
  to decrease.  An increase in vacuum cannot always be used,
  however, because there is a trade-off between increasing the
  vacuum and  avoiding excessive air infiltration.
       If a second exceedance occurs, the location must be
  remonitored within 10 days.  If the methane concentration
  meets or exceeds 500 ppm three times within a quarterly
  monitoring  period, the source must install an additional
  collection  component within 120 days of the original
  exceedence. Therefore, if the vacuum is increased as much as
  possible without excessive infiltration, and the third
  monitoring  of surface methane concentration still reaches or
  exceeds 500 ppm, installation of an additional well  is
  warranted.

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     Because disturbance of the cover can coincide with an
ineffective area of influence, the EPA has allowed an
additional 10 days after the occurrence of the second
exceedance.  The EPA believes it would be possible for
landfill personnel to locate and repair cracks or other flaws
in the landfill cover that were detected after an exceedance
                                                • %
was recorded.  Such exceedances may have resulted, at least in
part, from an ineffective area of influence.  If this occurs,
excessive methane concentrations may be monitored in the
subsequent monitoring period in spite of the repairs to the
cover.  In this case, an adjustment to the vacuum at adjacent
wells may still restore surface methane concentrations to
acceptable levels.  Therefore, 30 days are allowed to attempt
to reduce surface methane concentration to below 500 ppm
before the installation of an additional well would be
required.
     In both cases of unscheduled system expansion (i.e., when
negative pressure cannot be maintained or when methane
concentrations exceed 500 ppm), 120 days are allowed for the
installation of the required well or other collection device.
More time is allowed than for scheduled expansions because the
availability of materials, drilling rigs or contract personnel
on short notice is less certain.
     Comment;  One commenter (IV-D-19) warned that a variety
of operational considerations may affect the installation and
operation of collection and control systems.  The
considerations the commenter mentioned were:  equipment
traffic, settlement of landfill cover surfaces, effects of
bailed waste, changing topography, weather, barometric
pressure, on-site structures, gas generation rate, maintenance
and repair, and existing passive venting systems.
     Response;  The EPA agrees that these considerations will
have an affect on the installation and operation of collection
and control systems,  as they do with many systems in various
industries.  All of these considerations, however, vary from
site to site, and are best addressed by the local operator.

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  The final standards have been revised to require owners and
  operators to submit site-specific design plans, prepared by a
  professional engineer, to the Administrator for approval.
  2.14 COMPLIANCE
       Comment;  One commenter  (IV-D-45) stated that all
  landfills should be addressed under the proposed regulation
  and requested provisions allowing coordinated emission control
  between new and existing landfills within close proximity to
  each other.
       Response;  The regulations require that the control
  device used for either new or existing landfill emissions be
  demonstrated to achieve 98 weight-percent efficiency.
  Co-control among landfills is allowed as long as
  98 weight-percent efficiency  is achieved.  However, the EPA
  does not plan to promulgate specific provisions to address
  co-control among landfills.   Furthermore, not all landfills
  require control.  See section 2.4.1 for rationale for the
  selected design capacity and  emission rate cutoffs.
       Comment;  One commenter  (IV-D-7) indicated that they had
  designed a gas collection well equipped with a 48-in diameter
  well from the bottom up beginning at the liner level, and the
  commenter questioned whether  this successful design would be
  allowed under the proposed regu-ition.  The commenter
  indicated that the proposed regulations will be a burden on
  landfills with active gas collection systems already
  installed.  The commenter suggested exempting these landfills
  under the BDT definition or else exempting them if they are
  below the EPA's proposed significance level of 40 tons/yr of
  NMOC.
       Response:  Specific prescriptive designs have been
  eliminated from both the NSPS and the EG, and a design plan
  meeting the conditions of S 60.752(b)(2)(i) or S  60.33c(b)
  must be submitted to the Administrator for approval.  Thus,  as
  long as the system meets the  criteria in the rule and the
  design plan is approved, a well  of any design may be  included.
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        For an existing system,  the owner or operator may
   continue to use the existing system as long as the system is
   effectively collecting LFG from all gas producing areas of the
   landfill, and negative pressure can be maintained at each
   wellhead without excess air infiltration.  Quarterly
   Monitoring must also show surface methane concentrations below
   500 ppm.  The adequacy of the system must be demonstrated to
   the State regulatory agency.
        Collection and control systems are required only if the
            *
   landfill design capacity exceeds 2.5 million Mg or
   2.5 million m3 and the annual NMOC emissions exceed 50 Mg/yr,
   calculated by procedures specified in the rule.  Landfills
   below these cutoffs do not need to submit a collection system
   design plan or install a system.
        Comment;  One commenter (IV-D-2)  stated that collection
   systems have been estimated to be 60-percent efficient on
   average, and that landfills near residential areas should be
   required to have a 95 percent efficient collection system and
   a 99.99 percent efficient treatment system.
        One commenter (IV-D-19)  stated that a 98 weight-percent
   effective gas collection system efficiency is often not
   achieved because of variability of gas generation,
   decomposition rates,  and gas distribution resulting in
   efficiencies of 40 to 80 percent.   Therefore, they suggested
   that the regulations reflect that existing gas control systems
   in place at established landfills should be allowed to
   continue operation if they collect gas at a reasonable rate.
        Response;   The 98 weight-percent referred to in the
   regulation is a 98-percent reduction of collected emissions
   not a 98 percent emission collection efficiency.   A percent
   reduction standard is not specified for gas collection systems
   because it is difficult and impractical to quantify the
   performance of a gas collection system.  Therefore, a design
   and work practice standard has been set for gas collection.
   Site-specific risk factors such as location are not addressed
   by the NSPS program which is  intended to provide uniform

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  national minimum standards based on BDT.  State and local
  programs can address site-specific problems.
  2.14.1  Compliance—Schedule
       Comment;  Several commenters  (IV-D-19, IV-D-20, IV-D-27,
  IV-D-29, IV-D-56) contended that more time would be required
  to come into the various phases of compliance.  One commenter
  (IV-D-56) requested that additional time be allowed in order
  to spread out the costs of designing and installing the
  control system.  Another commenter  (IV-D-19) said
  administrative delays at municipally run landfills, such as
  mandatory requirements to obtain competitive bids before
  ordering equipment, may often warrant more flexibility in the
  time schedule.
       Another commenter  (IV-D-27) anticipated that there would
  be significant delay in adequate review and approval of
  submitted designs, due mostly to lack of expertise with LFG
  collection system design within the State offices.  The
  commenter recommended that owners and operators experiencing
  such delays should be granted an extension on the time allowed
  for installation of the system, rather than being required to
  install the system prior to approval in order to meet the
  1-1/2 year deadline within the proposed regulation.
       Another commenter  (IV-D-17) was concerned that the
  technical expertise needed to meet the requirements of the
  regulation are beyond most of the municipal landfill operators
  capabilities.
       One commenter  (IV-D-32) questioned whether
  S 60.752(b)(2)(ii) of the proposed rule, which requires the
  installation of a collection and control system within
  1-1/2 years of submittal of a design plan or notification of
  intent, refers to the final or initial stages of installation.
  Furthermore, the commenter stated that the time period of
  1-1/2 years may be too  lengthy.  The commenter recommended
  that the time period be reduced to 1 year if the design plan
  submitted is modeled after the specifications and 6 months to
  begin the installation  of a collection and control system.

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        One commenter (IV-D-39)  suggested that the requirement
   that gas collection systems be installed at landfills not
   meeting the proposed 150 Mg/yr emission rate cutoff within
   30 months of the effective date of a State emission standard
   be changed to allow for the phasing in of the program based on
   calculated NMOC emissions at each landfills.   The commenter
                                                   •»
   provided an example in which landfills with emission rates
   greater than 300 Mg/yr could be required to be in compliance
   within 30 months,  those with rates at or between 200 and
   300 Mg/yr could have 48 months,  and those with less than
   200 Mg/yr could have 5 years.   The commenter maintained that
   this phased approach would allow the regulatory burden to be
   spread out, since only a limited number of qualified
   contractors exist to perform the work and would target the
   efforts of the regulatory agency on those facilities with the
   greatest impact on the environment.
        One commenter (IV-D-45)  requested that the proposed
   period of 1 year to submit notification of intent to install
   collection and control systems be reduced to 3 months.
        Response;   As was explained in the proposal preamble, the
   EPA has established the compliance times for the submittal of
   the notice of intent to install a collection system designed
   in accordance with proposed S  60.758,  now § 60.759, for review
   on the assumption that all site-specific testing that could be
   performed to exempt the landfill from control would be
   performed.  A 3-month period between exceeding the regulatory
   cutoff and notification or plan submittal,  as recommended by
   one commenter,  would not be sufficient for those owners and
   operators electing to perform site-specific testing to verify
   that the regulatory level has  been exceeded or demonstrate
   that emissions are below the regulatory cutoff.  Although the
   EPA does not believe that all  owners and operators would
   perform all the site-specific  testing,  it does not want to
   penalize those owners and operators who commit to install a
   system based on the earlier, more conservative, tier
   calculations either.

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       As was also discussed in the proposal preamble, the EPA
  expects that owners and operators would likely consult vendors
  and suppliers at the time of system design, which occurs
  within the first year after the regulatory cutoff is reached.
  This leaves an additional year and 9 months for the resolution
  of permitting difficulties.  In the case of new MSW landfills,
                                                  • x
  the EPA recommends that the initial permit include provisions
  addressing the installation of a collection system, should  it
  become necessary.
       In the case of existing MSW landfills, the first NMOC
  emission rate report would be submitted 90 days after
  promulgation of the State emission standard.  The States will
  be required to submit their plans for Agency review and
  approval 9 months from promulgation of the final EG.  The EPA
  must approve or disapprove the State plan within 4 months of
  submittal.  Therefore, more than a year will likely pass
  before an existing MSW landfill would submit an NMOC emission
  rate report.  Owners or operators of existing landfills might
  elect to perform the Tier 1 calculation ahead of time, in
  order to evaluate what future requirements might apply to the
  existing landfill.  Finally, if permitting or other
  administrative hurdles cannot be overcome in a timely manner,
  the State may provide a longer compliance schedule pursuant to
  the provision of S 60.24(f)(3), based on "other factors
  specific to the facility  (or class of facilities) that make
  application of a less stringent standard or final compliance
  time significantly more reasonable"  (emphasis added).
       Comment;  One commenter (IV-D-21) recommended that
  5 years be given for control compliance for energy recovery,
  instead of 3 years, because of the additional commercial and
  regulatory considerations.
       Response;  As provided in the regulation, the EPA feels
  that 3 years  is adequate  to install  a collection and control
  system.  No special provisions will  be provided to use an
  energy recovery system.   Using an energy recovery system is at
  the discretion of the landfill owner/operator and is not

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required by the regulation.  An energy recovery system can be
installed at a date after an initial control system is
installed, but it is at the discretion of the landfill
owner/operator and is not required by the regulation.
     Comment:  Two commenters (IV-D-18, IV-D-45) proposed that
landfills close to exceeding the regulatory emission rate
cutoff should not be allowed to accept additional waste until
the collection and control system has been approved  (IV-D-18)
or installed (IV-D-45).
     Response:  The EPA views the regulatory emission rate
cutoff as a threshold initiating the process of system design
and installation, rather than a limit above which an
unacceptable risk exists.  This is why a landfill is
considered to be "controlled" once a design plan has been
submitted.  The EPA recognizes that the process of system
design and installation takes time, but does not agree that
prohibiting waste acceptance until system approval and
installation is warranted, as long as the owner or operator is
proceeding through the process.
2.14.2  Coropliance--System Shutdown
     Comment;  One industry commenter (IV-D-27) recommended
that integrated surface sampling be required during collection
system shutdown to demonstrate "safe" surface emission levels.
The commenter further recommended that owners and operators be
required to keep records on each of these events.
     A second commenter (IV-D-55) recommended that all flare
systems be required to have automatic blower shutdown and
valves to instantly stop the flow of LFG to the flare when
there is a flame-out.   The commenter also recommended that
flares be required as backup systems where energy recovery
systems are installed because downtime is more frequent with
turbines and I.e. engines.
     The commenter also stated that the negative pressure
requirement limits the operator's ability to shutdown part or
all of the collection system on a temporary basis for
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  maintenance, repairs, and changes in gas flow  (see also
  section 2.13, for more detail on changes in gas flow rate).
       Response;  In response to these commenters, the EPA has
  provided specific provisions regarding system start-up,
  shutdown, and malfunction in 5 60.755 of the final NSPS which
  reads as follows:
                                                  • *
       "(e)  The provisions of this subpart apply at all
       times, except during periods of start-up, shutdown,
       or malfunction, provided that the duration of
       start-up, shutdown, or malfunction shall not exceed
       5 days for the collection systems, and shall not
       exceed 1 hour for treatment or control devices."
       The various provisions recommended by the commenters were
  considered; however, the EPA wanted to avoid adding provisions
  that are not directly linked to compliance.  Compliance with
  the standards for collection systems is the installation and
  operation of a properly designed system.  The surface emission
  limit added as part of the surface emission monitoring was
  included under the operational standards.  The EPA is using it
  to verify that the system is adequately operated and
  maintained, and not to ensure an emission limit, surface or
  otherwise, as normally required under section 111.  For
  example, surface sampling may demonstrate that emission levels
  are increasing when the collection system is shut down, but a
  shut-down system cannot possibly meet a standard requiring
  that a collection system be actively collecting LFG.
  Therefore, in this case, getting the system back on line is
  the primary concern.
       The 5-day period for collection systems was selected in
  recognition that a major problem with a collection system will
  likely take longer than an hour to locate and solve but also
  that the landfill is not going to stop generating LFG.
  Localized problems with crushed pipes, etc., may be resolved
  through adjustments to the draw from other wells in the
  vicinity until repair is effected.  If the blowers need to be
  repaired or replaced, the collection/control system may be
  able to function temporarily as a passive system while repairs

klk-85\0
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   are effected.   However,  the EPA has no data upon which to base
   how long such an arrangement would be feasible.   Therefore,
   owners and operators should take care to plan for such
   contingencies.  A 5-day initial attempt at repair has been
   required in other regulations requiring that VOC-laden gas be
   routed to a control device.  Absent any clear data to support
   a different time-period, the EPA has adopted that repair
   period for this NSPS.
        Similarly, requiring a backup flare when an energy
   recovery device is used for control is one method of ensuring
   that LFG can be routed to a backup device while  such systems
   are down.   It could be argued that backup flares should also
   be required for those sites electing to use flares for
   controls.   In practice,  however,  most sites currently
   collecting landfill gas have multiple control devices, whether
   multiple flares,  i.e.  engines or turbines or combinations of
   the above.   Therefore,  only a short period of time would be
   necessary to relight a flare or reroute the collected gas to
   an alternative device.   For purposes of these regulations, the
   issue is that the gas is routed to a control device,  not what
   specific provisions the owner or operator has made to ensure
   that control is achieved.   Whether the owner or  operator has
   arranged with vendors for quick turnaround on replacement
   parts,  has spared system components on site,  or  has multiple
   devices on line so that the flow may be distributed among
   them, compliance may be maintained without the EPA specifying
   a particular strategy.   Therefore,  the EPA has elected to
   specify a downtime that is acceptable under these regulations,
   and leave the  strategy on how to comply to the owners and
   operators to negotiate with the appropriate regulatory agency.
        After consideration of the comment regarding automatic
   blower  shutdown,  the EPA has included provisions requiring
   that the gas mover system be shutdown and all valves  to the
   collection and control  system closed whenever the control
   device  is inoperable.   The provisions also require that the
   control device be operated at all times when LFG is routed to

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  the device.  Again,  in an effort to avoid requiring that
  landfill owners and  operators comply with the NSPS in only one
  of many alternative  means of compliance, the EPA is not
  requiring that this  be accomplished through the use of
  automatic devices.   While these devices may be appropriate in
  many cases, there may be very small systems that could be just
  as easily shut down  manually.  If landfill emissions were
  routed to the atmosphere through the collection and control
  system for  some portion of an hour, this would still be a
           •
  relatively  small emission event.
  2.14.3  Compliance—System Expansion
       Comment;  One commenter  (IV-D-17) stressed that requiring
  gas collection in areas that continue to accept waste is too
  costly for  operators because these collection systems will be
  deserted within a short time after the area reaches capacity.
  The commenter suggested that only those parts of a landfill
  which have  received  the final cover should be required to
  install emission controls.  Another commenter (IV-D-29) stated
  that the criteria for installing wells should be based on
  emission potential in a given area rather than a 2-year
  requirement.
       A third commenter  (IV-D-22) added that it often takes
  more than 2 years for a given area to achieve final grade and
  to be closed with the application of a final cover.  The
  commenter said that  the appropriate time for installing wells
  needed to be determined on a site-specific basis.  The
  commenter asked if "area" was defined.
       Three  commenters  (IV-D-20, IV-D-29, IV-D-39 and IV-F-3)
  advised that the 2-year time frame requirement for installing
  extraction  systems is not reasonable and/or does not appear to
  coincide with common operational practices at MSW landfills.
  One of the  commenters  (IV-D-20) recommended that all landfills
  be required to achieve final grades in a given phase as soon
  as possible and to close those portions thereof annually.  The
  commenter further recommended that the owner or operator be
  required to incrementally extend the extraction well field to

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   all recently closed areas every 2 years after filling begins
   in a phase.   Another of the commenters (IV-D-29)  said control
   in an active landfill should be determined by specific
   criteria instead of a time limit.
        One commenter (IV-D-27) requested that owners and
   operators be allowed the flexibility to demonstrate that
   additional wells are not necessary due to low gas production
   levels in a  given area, and not have to install additional
   wells within 2 years of waste deposition,  as required by the
   proposed regulation.   The commenter suggested that greater
   clarity about when collection must commence in each new cell
   is needed.
        Response;  As a result of further analysis in response to
   commenters'  concerns, the EPA has modified the final NSPS to
   require installation of wells or other collection devices
   within 60 days of the date in which the initial solid waste
   has been in  place for a period of 2 years or more for areas
   closed or at final grade, or 5 years or more for active areas.
        The 5 year period is believed to be more reasonable and
   consistent with common landfill practices than the proposed
   2-year period for active areas of the landfill.  Landfill
   areas are typically active for more than 2 years.   If
   collection system wells were required for all areas within
   2  years,  they would likely be covered over.   The covering of
   these wells  would either decrease their operational life, or
   require extension of the well upward,  significantly increasing
   costs.   A period longer than 5 years is not allowed because
   emissions from a given block of waste will decline over time,
   so it is important to install collection and control systems
   as soon as reasonably practical.   For areas that are closed or
   at final grade,  collection systems must be installed within
   2  years,  as  at proposal.
        The final provisions allow the exclusion of
   "nonproductive"  areas in § 60.759(a)(3)(ii).   This provision
   may be used  to exclude areas from control,  so long as the
   aggregate emission potential of all areas excluded under this

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  provision is less than 1 percent of the landfill's overall
  emission potential.   (Segregated areas of asbestos or
  nondegradable waste nay also be excluded and are not subject
  to the 1 percent criteria.)
       As discussed in  chapter 3 and appendix D of the proposal
  BID  (EPA-450/3-90-011a), the gas generation rate model used in
                                                   • >
  the  development of these regulations assumes that after a
  negligible lag time,  the gas production rate is at its peak
  for  a discrete mass of waste, and decreases exponentially
           •
  thereafter as the organic fraction of the refuse decomposes.
  Although the lag time is characterized as negligible,
  according to the gas  generation rate model used, it can vary
  from several weeks to a few years.  This peaking rate followed
  by rapid decline is the basis for the 2-year collection
  requirement at closed areas.  The 5-year period for active
  areas was added to be in keeping with current operational
  practices at MSW landfills and to reduce costs and
  inefficiencies that would be associated with installing wells
  in active areas and then covering them over as more refuse is
  deposited.  The EPA considers this 2-year/5-year split a
  common sense approach to ensure that all gas producing areas
  are  being appropriately controlled.
       Since the calculation of the overall emission rate
  involves summing the  emission rate from each yearly submass of
  refuse, and the rates will vary inversely with age, the
  maximum production from an area for purposes of these
  regulations will occur close to the time of its deposition,
  and  its contribution  to overall emissions will decline
  continuously thereafter.  It is important, therefore, to
  install collection wells into refuse as soon as possible.
       The same calculation that establishes overall emissions
  can  be used to calculate emissions from discrete segments of
  waste, provided that  the age of the refuse is known.  Since
  the  model takes into  account the age of the refuse,
  theoretically, the individual annual fills can be ranked by
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   productivity and the least productive excluded from control
   (up to l percent of total emissions).
        It is important to note that the exclusion of refuse from
   collection does not extend to the determination of
   applicability.   All waste present in  the entire landfill must
   be included in the calculation of the overall NMOC emission
                                                   •»
   rate for purposes of determining whether gas collection and
   control is required, except for segregated,  documented masses
   of nondegradable refuse such as cement or nondegradable
           *
   demolition wastes.
   2.15 RECORDKEEPING AND REPORTING
        Comment;   Several commenters (IV-D-17,  IV-D-27 and
   IV-F-5, IV-D-36) requested that the EPA provide additional
   clarification about the reporting and recordkeeping
   requirements.   Three commenters (IV-D-20, IV-D-27, IV-D-36)
   said that the reporting and recordkeeping requirements were
   too administratively burdensome.   One of the commenters
   (IV-D-27)  contended that the recordkeeping and reporting
   provisions of the proposed regulations were too burdensome to
   the State agencies responsible for reviewing them and that
   annual instead of semiannual submissions should be required.
   The commenter also suggested that greater clarity about the
   various elements necessary in each report is needed.   However,
   three commenters (IV-D-36, IV-F-5,  IV-F-6)  proposed that if
   the reporting and recordkeeping effort was in support of data
   base development, even landfills below the proposed design
   capacity exemption should participate.
        Response:   The recordkeeping and reporting requirements
   of the NSPS include only those records and reports necessary
   under the provisions of section 111 to verify applicability
   under or exemption from the standards, that control equipment
   is properly operated and monitored, and to verify compliance.
        The design capacity report alerts the regulatory
   authorities to  the presence of a landfill subject to the
   standard,  whether or not that landfill is subject to control.
   The NMOC emission rate reports track  the increase in emissions

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  at subject landfills and indicate when control will be
  necessary.  The closure report is necessary to indicate that
  either an uncontrolled source will never be subject to
  control, or that removal of controls at a controlled source is
  approaching.  The equipment removal report allows the
  authority to review the basis for equipment removal and to
                                                  • %
  verify that all three criteria are met.
       The purpose of the proposed semiannual report was to
  verify that the collection and control system was operated in
           •
  compliance with the standards and to provide information on
  the frequency and duration of noncompliance periods.  The
  regulations list the information to be included in each
  report.
       After considering the comments and the Agency's
  initiative to reduce recordkeeping and reporting burdens, the
  frequency of the semiannual report has been changed to annual.
  By reducing the frequency, the cost burden of generating
  reports will be reduced.  Information on noncompliance periods
  will still be reported within a year of their occurrence,
  which is sufficient to allow timely enforcement of the rule.
  An annual reporting period is consistent with other NSPS and
  with the Title V permit program requirement for annual
  compliance certification.
       All of the records required under the NSPS are necessary
  so that the design, installation, and performance of the
  system can be shown to comply with the NSPS.  The reports
  submitted by landfills above the design capacity exemption
  provide substantial amounts of data for review.  Requiring
  calculation of emission rates and reports by MSW landfills
  below the design capacity exemption would be an unwarranted
  burden and is not necessary to ensure that the regulations are
  met.
       Comment:  Two industry commenters  (IV-D-27, IV-D-32)
  requested that the EPA clarify the information required for
  the closure report referenced in S 60.756 of the proposed
  NSPS.  The commenters also said that the compliance report

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   required in § 60.756(e)  of the proposed NSPS only addresses
   vertical well systems,  and needs to be expanded to cover any
   approved design,  such as is allowed in S 60.752.
        Response:  The closure report in § 60.757 of the final
   NSPS must certify that waste deposition has ceased at the
   landfill, and that additional waste deposition will not occur
   without permit modification as described under S 60.7(a)(4).
   Since the gas-generation model used results in a decreasing
   NMOC emission rate for each unit of landfilled waste over
   time, once waste deposition has ceased, the calculated NMOC
   emission rate would continually decrease after closure.
        In response to the commenters concern about compliance
   reporting for alternative designs,  the EPA reanalyzed the
   requirements.  The final rule no longer provides specific
   design specifications.  Instead,  it provides criteria for
   active gas collection systems (see § 60.759).   Design plans
   for systems meeting these criteria must be prepared by a
   professional engineer and approved by the Administrator.  In
   addition, S 60.752(b)(2)  of the final rule allows for design
   plans for collection and control systems that do not meet the
   criteria in § 60.759.  These provisions will allow use of any
   type of active or passive system as long as it meets the
   general criteria in S 60.752(b)(2)  and an adequate design plan
   is submitted and approved.   In addition to design information,
   design plans must include any alternatives to the operational
   standards,  test methods,  compliance procedures,  monitoring,
   recordkeeping or reporting provisions and a demonstration to
   the Administrator's satisfaction of the equivalency of the
   alternative provisions.
        qppment;  One commenter (IV-D-18)  suggested that if it
   appears that at any time in the future a landfill will meet
   the proposed emission rate cutoff of 150 Mg/yr and a
   collection and control  system will need to be installed, then
   a  notification of intent to install a collection system should
   be submitted immediately.
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       Response:  The notification of  intent to  install a
  collection or control system design  plan must  be submitted
  within  1 year of the report of the determination that the
  emission rate exceeds 50 Mg/yr.  The timeframe for submittal
  of the  design plan was developed after careful consideration
  of typical testing and reporting intervals, and w%ith a
  sensitivity to the variability inherent in landfill
  operations.
       Land.fill emissions vary substantially over time.
  Designing collection and control systems requires considerable
  resources, and design plans should not be required unless it
  is evident that control will actually be required.  Waste
  acceptance rates, landfill practices, and local regulations
  change  frequently enough that a design plan that seems
  appropriate today for a need anticipated in the future may
  actually be infeasible when the time comes to  install.   In
  some cases, waste acceptance rates may even decrease resulting
  in lower emissions than predicted.   For example, rates might
  decrease if a given community were to prohibit the acceptance
  of yard waste.  Some landfills may close down  before the
  anticipated emission rate is reached.  The EPA is not prepared
  to require landfill owners and operators to expend resources
  developing a  collection and control  plan before it is
  reasonably certain that the system will, in fact, be required.
       Comment;  Three commenters  (IV-D-20, IV-D-51, IV-D-54)
  argued  that the proposed 100,000 Mg  design capacity exemption
  for reporting requirements is too low in relation to the
  proposed 150  Mg/yr rate of NMOC emissions required to  install
  controls  (IV-D-51 included model parameter information). Two
  of the  commenters  (IV-D-20, IV-D-54) cautioned that this will
  burden  small  landfills and State regulatory agencies.  They
  claim that proper cutoffs for periodic reporting for emission
  rate cutoffs  of 150 and 100 Mg/yr of NMOC are  550,000 Mg of
  waste and 375,000 Mg of waste, respectively.
       One commenter  (IV-D-44) stated  that due to difficulties
  of estimating the lifetime and design capacity of landfills,

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   the cutoffs for reporting for levels of 150 Mg/yr of NMOC
   apply only to landfills within an acceptance rate exceeding
   35,000 Mg/yr.
        Another of the commenters (IV-D-20)  suggested that design
   volume, and not waste mass as proposed by the EPA, be used in
   deciding the reporting cutoff level.  The commenter (IV-D-20)
   presented data on waste compaction density and advised that
   data on design volume is easier to compile and will be less of
   a burden on States to regulate.
        Response:   The design capacity exemption was reevaluated
   in the interim between proposal and promulgation, and has been
   revised to 2.5 million Mg or 2.5 million m3.   This level was
   chosen because it significantly reduces the reporting and
   recordkeeping burden on the landfills as well as the State and
   local agencies, while only about 15 percent of the potential
   NMOC emission reductions are lost.  Setting a reporting
   requirement based on annual acceptance rate does not take into
   account that the landfill could have large amounts of refuse
   in place emitting more than 50 Mg/yr.  Section 2.4.1 of this
   chapter,  "Design Capacity Exemption," includes further
   discussion on this topic.
        Comment;  One commenter (IV-D-32)  stated that S 60.753(b)
   of the proposed regulation,  which discusses the calculation of
   the NMOC emission rate after a gas collection system is
   installed,  is unclear about whether the calculated NMOC
   emission rate should be reported,  and if so,  how often and to
   whom.  The commenter also questioned what should be done if
   calculated emissions exceed 150 Mg/yr and whether this NMOC
   calculation will be the basis for collection system
   modifications.
        The commenter (IV-D-32)  recommended that S 60.756(a)(1)
   of the proposed regulation specify the scale of the map which
   the regulation requires to be submitted.   The commenter also
   suggested that S 60.756(d)(1)(iii) of the proposed regulation
   include a reference to the correct method and equation to be
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  used in calculating NMOC emissions reports required by the
  collection equipment removal report.
       Response;  Section 60.754(b) of the final NSPS provides
  an equation to calculate the NMOC emission rate after a
  collection system has been installed.  This calculation is
  necessary to determine the NMOC emission rate for a
                                                  • \
  pre-existing system and for system removal.  A landfill is
  exempt from the requirement to calculate and report an annual
  NMOC emission rate [see §S 60.752(b)(2) and 60.757(b)(3)]
  while complying with the provisions for collection and
  control.  The NMOC emission rate must, however, be calculated
  in order to meet the conditions for system removal in
  S 60.752(b)(2)(v).  Since better information for estimating
  the NMOC emission rate would be available from the system, the
  EPA is requiring the use of procedures including this
  information as a condition for system removal.  The final
  regulation does not specify the scale of the landfill map, but
  leaves this decision up to the discretion of the landfill
  owner or operator.  Different scales may be appropriate to
  present different configurations.
       Comment;  One commenter  (IV-D-32) stated that the
  regulation does not distinguish between isolated units of a
  landfill that may have been closed years ago and units that
  are still accepting waste.  The commenter pointed  out that the
  older portions would be used to calculate NMOC emissions and
  this would not represent the NMOC emissions of the newer
  portions.  The commenter recommended that these issues be
  resolved and that a registered civil engineer or certified
  engineering geologist certify that the site is closed before
  it is considered closed.
       Response;  The equation for estimating NMOC emissions in
  S 60.754(a)(1)(i) of the final NSPS accounts for reduced
  emissions from older portions of a landfill by utilizing the
  actual year-to-year waste acceptance rate.  If the
  year-to-year waste acceptance rate is not known, the  equation


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   presented in S 60.754(a)(1)(ii)  of the final NSPS must be
   used.
        Comment:   One commenter (IV-D-18) requested that the EPA
   revise the provisions for compliance reports to include
   immediate documentation of equipment malfunctions.  In
   addition, the commenter argued that semiannual reports should
   be made public.  Another commenter (IV-F-6)  stated that flare
   flame outages should be reported if they exceed 1 hour.
        Response:  Since proposal,  the semiannual reports have
   been changed to annual reports in order to reduce the
   reporting burden.  As specified in the final rule, annual
   reports must contain the following information:
        (1)   Value and length of time for exceedance of monitored
             parameters.
        (2)   Description and duration of all periods when the gas
             stream is diverted from the control device or has no
             flow rate.
        (3)   Descriprion and duration of all periods when the
             control device was not operating for a period
             exceeding 1 hour and length of time the control
             device was not operating.
        (4)   All periods when the collection system was not
             operating in excess of 5 days.
        (5)   The location of each exceedance of the 500 parts per
             million methane concentration and the concentration
             recorded at each location for which an exceedance
             was recorded in the previous month.
        (6)   The date of installation and the location of each
             well or other collection device added to the
             collection system pursuant to S 60.755.
       As stated under (3)  above,  flare flame outages of less
   than one  hour  are not required to be reported in the annual
   report.   However, all periods exceeding one hour must be
   included  in the report.   The 1-hour time period assures that
   significant emission events are  reported,  while allowing for
   short-term problems that  are rapidly corrected.  There are

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  unavoidable circumstances that will cause short term problems
  in the operation of flares and other control devices.  The
  1-hour time period is reasonable to allow operators time to
  discover the problem and correct it or route emissions to a
  back-up control device.  The amount of emissions released in a
  period shorter than 1 hour would be relatively small.
       The public may obtain copies of annual reports by
  contacting the government agency or landfill operator
  responsible for the reports.  The availability of information
           •
  to the public is discussed in 40 CFR 60.9.
       Comment;  Two commenters  (IV-D-18, IV-D-45) requested
  that landfills be required to submit annual reports and not be
  allowed to submit the 5-year estimates allowed under the
  proposed regulations because of the negative health affects of
  NMOC.
       Response;  The report submitted with the 5-year estimates
  is the same report as the annual report except emission
  estimates are reported  for 5 years instead of one.  The only
  factor affecting the accuracy of the 5-year report that does
  not influence the 1 year report, is the difficulty in
  predicting acceptance rates in the future.
  Section 60.757(b)(1)(ii) of the final NSPS requires the owner
  or operator to submit a revised 5-year report if the
  acceptance rate exceeds the estimated waste acceptance rate in
  any year reported in the 5-year estimate.  The EPA considers
  the 5-year report as effective as 5 annual reports in tracking
  NMOC emission potential.
  2.16 REGULATORY OVERLAP
       Comment:  One commenter  (IV-D-19) voiced concern about
  the regulatory overlap  due to differing regulatory
  requirements between local, State, and Federal agencies.  The
  commenter suggested creating provisions to increase
  coordination among the  various agencies to aid in permitting,
  and other administrative duties.  Another commenter  (IV-D-39)
  commented on the statement, "the State, county, or
  Administrator may request other reasonable information as may

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   be necessary to verify the maximum design capacity of the
   landfill" and "reported NMOC emission rate."   The commenter
   stated that the inclusion of three separate governmental
   bodies in the requirement is unworkable and will place undue
   burdens on the landfill owners/operators in responding to
   information requests.   Also, the commenter was concerned with
   the fact that the term "reasonable" is undefined and since no
   authority has been granted to a regulatory agency to determine
   "reasonableness," it would be possible that allowing this
   provision could be used to delay operations at a landfill.
   The commenter recommended that "State,  county,  or
   Administrator" be deleted from the requirements and be
   replaced with "Administrator."  The term "Administrator is
   defined in the General Provisions to 40 CFR 60 as the
   Administrator of the EPA or his authorized representative.  In
   most cases,  the States have been authorized to implement NSPS.
        Response:  The EPA shares the commenters concerns over
   regulatory overlap and encourages States to increase
   coordination among agencies responsible for issuing permits.
   In order to reduce ambiguity,  the term "reasonable" will not
   be included in the final regulation as it is  not referred to
   in the General Provisions.   As requested by the commenter,
   references to State,  county, or Administrator will be replaced
   by the term "Administrator."  The term "Administrator" is
   defined in the General Provisions to 40 CFR 60 as the
   Administrator of the EPA or his authorized representative.  In
   most cases,  the States have been authorized to implement NSPS.
        Comment;   One commenter (IV-D-2)  stated  that the standard
   was inconsistent with  Federal  RCRA regulations.   The commenter
   explained that MSW landfills normally contain an unregulated
   amount of RCRA waste as household toxics,  and,  therefore,  the
   landfill should be subject  to  a greater level of control,  such
   as 99.99 percent instead of 98 percent.
        Response;  The EPA disagrees with the comment that the
   regulations are inconsistent with RCRA and that the presence
   of household wastes warrants greater control.   This rule is

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  based on BDT.  As explained in the proposal preamble and in
  section 2.6.3, the best demonstrated level of control is
  98 percent.  There are no demonstrated technologies that are
  applicable for all landfills that achieve 99 percent or
  greater reduction at a reasonable cost.  Household toxics may
  be included  in household waste, but air emissions resulting
                                                  • %
  from them are not subject to greater control under RCRA than
  under these  regulations.  A landfill subject to these
  regulations  is not exempt from any of its RCRA
           •
  responsibilities.  Air emissions from the landfill may also be
  subject to the BDT of the air criteria under 40 CFR 258.24 of
  subpart c.
  2.16.1  Superfund Interface
       Comment;  One industry commenter (IV-D-27) supports the
  designation  of BDT under these regulations as "applicable or
  relevant and appropriate requirements" for Superfund sites,
  noting that  properly designed passive systems should also be
  permitted for Superfund sites without synthetic liners, due to
  the short-term nature of many of these projects.
       One commenter (IV-D-48) stated that Superfund sites
  already address most of the factors  (ozone production,
  carcinogenic risk, threat of fire and explosion) listed in the
  proposed standards in support of gas collection and control
  systems.  The commenter explained that the majority of
  Superfund landfills contain only about 10 percent industrial
  wastes, yet  the financial burdens of control will be absorbed
  by industry  as the regulation is currently written.
       Response;  A Superfund site that is also a former MSW
  landfill that would otherwise be covered by these regulations
  presents identical concerns to those presented by a
  non-Superfund MSW landfill.  The applicability of these
  regulations  is based on NMOC emission rate.  If the Superfund
  landfill emits NMOC above the emission rate level,
  installation of a collection system  is appropriate and
  relevant, as well as applicable.  The collection system must
  meet the minimum design requirements in the EG which are

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   essentially equivalent to those of the NSPS.   Generally,
   passive systems with add-on control for the collected gases
   may not be as practical or economical as active systems,  but
   the regulations allow the use of them as long as they have
   liners and equivalency is demonstrated as discussed in
   S 60.752(b)(2)  of the final NSPS.
   2.16.2  Prevention of Significant Deterioration Interface
        Comment;  One commenter (IV-D-23)  requested clarification
   of whether the BDT in the proposed regulations will satisfy
   the BACT requirements under the PSD program and when further
   control measures should be implemented as part of BACT
   decisions.
        Response:   The BACT decision under the PSD program is
   made on a site-specific basis when the landfill is permitted
   in order to address a broader range of site-specific concerns
   than under section ill.  The BDT establishes a minimum control
   level for new landfills, and BACT decisions cannot be less
   stringent than BDT.  The BDT may serve as BACT in many cases.
   However,  a PSD review is still required for individual new or
   modified landfills that meet PSD applicability criteria,  and
   BACT will be determined during the review based on the
   considerations required under the PSD program.   The PSD
   program is separate from the NSPS; the NSPS regulation will
   not address BACT determinations.
        Comment:  One commenter (IV-D-17)  suggested that
   estimating ambient air contaminant levels using a screening
   method (they mentioned Air Guide 1,  NYSDEC)  would help
   determine the effects of NMOC on sensitive receptors within
   the surrounding landfill area.   The commenter requested that
   air review parameters (i.e., location of sensitive parameters,
   site wind rose,  etc.)  should be included under S 60.756 in the
   proposed regulation.
        Response:   These regulations are being developed and
   promulgated under section 111,  which requires the application
   of BDT,  not modeling of ambient concentrations at "sensitive
   receptors," as  required under the PSD program.

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       Comment:  One commenter (IV-D-54) stated that no changes
  would need to be made to the PSD provisions in 40 CFR 51.166
  and 40 CFR 52.21 if LFG is regulated as VOC.  The commenter
  explained that regulating MSW landfills under PSD would not be
  useful since new landfills are now covered under the NSPS
  which requires that BDT be used for the control of LFG.  The
                                                  • %
  commenter stated that since PSD increments or NAAQS have never
  been proposed for MSW emissions or NMOC, ambient air quality
  impact analysis for LFG or VOC would have no significance.
  The commenter noted that they have not come across any unit
  risk factor data for LFG.  The commenter also stated that LFG
  is generated as fugitive emissions and it is unlikely that a
  new or modified landfill would need to undergo
  pre-construction review since fugitive emissions would not be
  counted for applicability purposes under the existing federal
  PSD provisions.
       Two commenters (IV-D-26, IV-D-39) recommended that PSD
  review be based on existing PSD criteria and not on the new
  "de minimis" level for NMOC.  The commenters stated that there
  is no need to impose stricter PSD review standards on
  landfills for NMOC than those currently applicable to other
  industries and other sources which emit the similar compound,
  VOC, at equivalent or greater rates.
       Response;  The EPA is designating MSW landfill emissions
  as a designated pollutant under sections lll(b) and  (d) on the
  basis of both health and welfare impacts.  The MSW landfill
  emissions consist of a composite of pollutants including
  methane and NMOC.  The constituent pollutants that make up the
  MSW landfill emissions can vary significantly both within a
  landfill and from landfill to landfill.  Thus, to reduce the
  burden of measuring all components of MSW landfill emissions,
  the EPA is designating NMOC as a measurement surrogate for MSW
  landfill emissions.  The NMOC are designated because NMOC
  include VOC as the commenter has recommended, as well as
  photochemically nonreactive compounds,  including both toxic
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   and nontoxic compounds,  that are of concern under this
   rulemaking.
        A consequence of this action is that the PSD regulations
   would now apply to all MSW landfills defined as major sources
   which would  have "significant"  increases  in this pollutant
   (MSW landfill emissions  measured as NMOC).   Absent any
   significance levels in the PSD  regulations to exempt
   de minirois situations, PSD review would be triggered by any
   increase .in  MSW landfill emissions.  Thus,  to maintain a
   manageable review process, MSW  landfill emissions need to be
   added to the part 51 and 52 list of PSD pollutants and a
   significance level established.   The EPA  proposed to establish
   40 tons/yr (measured as  NMOC) as the significance level for
   MSW landfill emissions.   However,  in consideration of public
   comments, the final rule establishes a significance level of
   45 Mg/yr (50 tons/yr)  of NMOC.   Given the typical composition
   of landfill  gas,  a 50 tons/yr NMOC level  is comparable to the
   previously established PSD significance level of 40 tons/yr of
   VOC.   Under  NSR regulations,  a  PSD review would be required
   for increases in MSW landfill emissions at major sources at or
   above this significance  level.
        While it is true that the  PSD regulations state that
   fugitive emissions are not counted toward the potential to
   emit of a source category which is not specifically listed,
   the PSD regulations define fugitive emissions as those
   emissions which could not reasonably pass through a stack,
   chimney,  vent,  or other  functionally equivalent opening."  It
   is feasible  for a landfill to install a gas collection system,
   as is required for some  sources under these regulations.
   Therefore, MSW landfill  emissions,  which  can be collected, are
   not fugitive emissions for PSD  purposes.   Thus,  the
   commenters'  assertion that the  emissions  would not be counted
   to determine applicability is not valid.   These regulations
   also establish methods by which NMOC emissions from MSW
   landfills can be calculated and compared  to the lists in parts
   51 and 52, for PSD applicability purposes.

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       Comment;  One commenter  (IV-L-1) suggested that 40 tons
  per year of NMOC emissions be added to the definition of
  significance for nonattainment NSR at 40 CFR 51.165(a)(1)(x)
  in addition to those changes proposed to the PSD regulations
  at 40 CFR 51.166 and 52.21.
       Response;  Under the final rule, 40 CFR 51.166 and 52.21
                                                  • %
  have been amended to include 50 tons per year of NMOC.
  Nonattainment new source review at 40 CFR 51.165 covers only
  those pollutants for which NAAQS have been established.   Since
  NAAQS for NMOC have not been established, NMOC cannot be  added
  to the definition of significance for nonattainment new source
  review.  However, because VOC are a significant portion of
  NMOC and a significance level for VOC (related to the ozone
  NAAQS) is included in 40 CFR 51.165(a)(1)(x), landfills are
  sources that must be considered for nonattainment NSR.
       Comment;  Two commenters  (IV-D-26, IV-D-39) said that
  clear guidelines for PSD review should be established so  that
  timely, objective decisions can be made as to whether either
  PSD permits will be required or determinations of
  nonsignificant impact will be granted to the landfill.
  Further, the commenter suggested that the EPA should decide
  whether there is a need for PSD review of new or modified
  landfills since open and/or enclosed flares are BACT, and no
  other practical methods of reducing methane and NMOC emissions
  exist.  One of the commenters  (IV-D-39) asserted that under
  the NSPS, proper landfill capping, reducing  leachate, and
  other landfill operational factors have no bearing  on the
  calculation of the NMOC emission rate.
       Response;  The New Source Review Workshop Manual provides
  guidance on the process by which new sources and major
  modifications are evaluated for applicability to the PSD
  regulations.  This manual was published in draft form in
  October of 1990.  In addition, for MSW landfills, the
  definition of a major source  (in 40 CFR parts 51 and 52)
  establishes the size at which emissions from a landfill are
  considered in determining whether or not the landfill is

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   major.   Further,  the definition of "significant" in those
   regulations will  include the threshold level at which an
   emissions increase is significant.
        The CAA,  in  section 165(a),  reguires that all major
   stationary sources and major modifications proposed for
   attainment areas  be subject to PSD review.  A PSD permit
                                                   •»
   review is a case-by-case evaluation of a proposed major new
   source or major modification.   A BACT determination is one of
   the reguirements  of a PSD permit review [see
   section 1*65 (a) (4)], and BDT may or may not equate with BACT.
   The EPA is currently selecting properly designed gas
   collection and combustion devices achieving 98 percent NMOC
   emission reduction as BDT for landfills emitting greater than
   50 Mg/yr of NMOC  under these rules.   However,  States may
   decide to consider other, or more stringent,  control systems
   as BACT, or reguire controls on landfills emitting less than
   50 Mg/yr of NMOC.   Thus, PSD review would still be needed for
   new or modified landfills.
        Comment;   Two commenters (IV-D-18, IV-D-45) wanted the
   standards to include provisions stating that MSW air emissions
   from landfills on National Park or Forest lands will not be
   allowed to negatively affect the air quality of these National
   Park or Forest lands.  In addition,  one of the commenters
   (IV-D-18)  suggested that lowest achievable emission reduction
   (LAER)  be used in place of BDT if any forms of waste are
   accepted from  outside of the National Park or Forest or if any
   Federal park or forest land is exchanged for the purpose of
   creating a landfill.
        Response;  The PSD program provides for the protection of
   air quality in those National Parks and National Forests
   designated as  Class I areas.   Major new sources and major
   modifications  in  PSD areas are required to apply BACT and to
   model air quality impacts,  including whether the proposed
   source would cause or contribute to exceedances of NAAQS or
   increments.  There are no -NAAQS or increments for "MSW
   landfill emissions," but other provisions of the PSD

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  regulation specifically designed to protect Class I areas
  still apply.  Concerned Federal land managers may, for
  example, use the air quality impact analyses to determine
  whether there will be an adverse impact on AQRVs.  If the
  reviewing agency agrees with a Federal land manager's adverse
  impact determination, the agency must deny the permit.
       For National Parks and other federal lands not classified
  as Class I, the PSD program still offers protection from MSW
  landfill emissions through the additional impacts analysis,
  which is an assessment each PSD permit applicant must make of
  the  impact the proposed source or modification will have on
  soil, vegetation, and visibility.  The Federal land manager
  can  argue that there will be unacceptable impacts based on
  these studies.
       Finally, there is no regulatory authority for requiring
  LAER for MSW landfill emissions because LAER applies only to
  major sources of a nonattainment area pollutant, and there are
  no attainment areas for MSW landfill emissions.  New or
  modified landfills may, however, be subject to nonattainment
  area major source review  (or to PSD review) if the VOC
  emissions from the landfill exceed the threshold levels for
  major status.  In attainment areas, the threshold for major
  sources is 250 tons/yr.   (For certain listed categories, the
  threshold is 100 tons/yr, but landfills are not one of the
  categories listed in the PSD rules, so the 250 tons/yr
  threshold applies.)  Fugitive emissions are not included in
  determining whether the 250 tons/yr threshold is exceeded, but
  collectable emissions must be included.  Because this NSPS and
  EG have found collection systems to be feasible, most landfill
  emissions are considered collectable for PSD purposes.  The
  EPA  estimates that approximately 70 percent of NMOC emitted by
  MSW  landfills is VOC as presented in the memorandum
  "Estimating the percentage of non-VOC constituents in
        \
  Municipal Solid Waste Landfill Nonmethane Organic Compound
  Emissions"  (Docket No. A-88-09, Item No. II-B-39).  If the VOC
  emission rate exceeds 250 tons/yr in attainment areas or the

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   major source threshold in nonattainment areas (from 100 down
   to 10 tons/yr,  depending on the severity of the nonattainment
   area), then the landfill constitutes a major source and is
   subject to the PSD or nonattainment area provisions regardless
   of its NMOC rate.
   2.16.3  Subtitle D Interface
                                                   " %
        Comment;   Two commenters (IV-D-7, IV-D-26 and IV-F-6)
   expressed concern for the cost, handling, and treatment of gas
   condensate, sometimes classified as a hazardous material,
   resulting from gas collection and energy recovery systems.
   One commenter (IV-D-7)  requested that the EPA keep in mind the
   outcome of having all future subtitle D landfills regulated
   partly as subtitle C (hazardous waste) landfills because the
   required gas collection system will produce gas condensate.
   Another commenter (IV-D-26)  suggested that gas condensates be
   either specifically excluded from or specifically included
   under subtitle C.
        Response;   The liquid from gas condensate is only a
   hazardous waste if it is tested and determined to be a
   characteristic hazardous waste.  A subtitle D landfill which
   generates a hazardous waste would not become a subtitle C
   landfill.  However,  the hazardous condensate would have to be
   handled at an appropriate TSDF.
        Comment;   One commenter (IV-D-15) wanted the EPA to
   discourage landfill siting in areas that already exhibit heavy
   pollution or that would add to deforestation.   The commenter
   further said that the siting of a landfill requiring the
   removal of trees should be given an emissions rating prior to
   receiving any waste because it has already degraded air
   quality by removing trees,  whereas the siting of a landfill on
   land already void of trees could be given a zero emissions
   rating.
        Response;   These regulations apply to air emissions from
   landfills.  The siting of landfills is covered by RCRA
   subpart D, part 258,  finalized on October 9,  1991
   (56 FR 50978).

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  2.17 STATE PROGRAM SUBMITTALS
       Comment;  One commenter  (IV-D-17) indicated that the
  requirement to submit a State program for implementing the EG
  to the EPA by the ninth month after promulgation was not
  reasonable because of the lack of revenues and resources
  needed to develop and implement a regulatory program such as
  this in such a short time period.
       Response;  The 9-month interval is mandated by
  section lll(d) of the CAA, and has been previously
           •
  incorporated into the NSPS/EG program in 40 CFR 60.23.
       Comment;  One industry commenter (IV-D-27) recommended
  that the EPA develop a standard form for Tier 1 calculations.
  Two commenters (IV-D-27 and IV-F-5, IV-F-4) requested that the
  EPA provide guidance and oversight to the States in
  implementing the proposed regulations, especially in the areas
  of the Tiers and system design.  The commenters were concerned
  that alternative designs would be difficult to get approved by
  review personnel.
       One commenter (IV-D-51) requested clarification of the
  regulated pollutant for the collection of fees under the air
  permit program required by the CAA.  In particular, the
  commenter requested specification of whether only NMOC, or all
  landfill emissions, are required to pay the air emissions fee.
       Response;  The EPA has developed a computer program,
  available on disk, to perform the Tier Calculations.  The
  computer program called the Landfill Air Emissions Estimation
  Model  (or LAEEM), can be obtained from NTIS,  (703) 487-4650.
  Government Agencies can also acquire the program from the CTC,
  (919) 541-0800 within BSD of OAQPS.  The program can also be
  down-loaded from the OAQPS CTC bulletin board system,  (919)
  541-5742.  The bulletin board system operator can be reached
  at  (919) 541-5384.  The computer program was revised and will
  be available when the regulations are promulgated.
       The EPA will publish guidance materials to assist in the
  implementation of and compliance with these NSPS and EG.  An
  enabling document focusing on assisting the agencies who will

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   be responsible for implementing the regulations will be
   available soon after the regulations become final.   These
   materials would also be useful to landfill owners and
   operators.  Additional enabling materials may also be
   available in the future to provide guidance to landfill owners
   and operators complying with the NSPS and EG.   The enabling
   documents may include forms for completing the calculations
   for Tiers 1, 2, and 3 to assist the landfill owner/operator
   and the implementing agency.
        Alternative collection and control system design plans
   are allowed under § 60.752 and require a demonstration to the
   Administrator's satisfaction of the equivalency of the
   alternative provisions to the criteria in S 60.759.  The rule
   has been changed since proposal to remove the prescriptive
   design specifications in S 60.759 and to require site-specific
   design plans for active collection systems that meet the
   criteria in S 63.759 as well as those that do not.   Thus, any
   design will require approval, and unique designs will not be
   discouraged.
        The recently promulgated Title V program includes
   provisions for the collection of fees from all sources of CAA
   pollutants.  This fee assessment was mandated by the CAA
   amendments of 1990 in order to provide relief to States in
   complying with CAA-mandated activities.
   2.18 POLICY ISSUES
   2.18.1  Consideration of Methane
        Comment:  Four commenters requested that methane
   emissions be considered to some degree in the development of
   the NSPS and EG.   One commenter (IV-D-24)  contended that
   methane reductions should have been considered directly in the
   selection of BDT because of methane's global climate change
   impacts,  which the commenter considered a public welfare
   effect warranting attention under section 111 of the CAA.  The
   commenter recommended using monetary values for CO2 and
   methane established by several utility regulatory bodies in
   the selection process,  noting that not to do so would be to

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  arbitrarily assign methane's harmful effects a value of zero.
  The commenter reported that Massachusetts has assigned methane
  a value of $220/ton for similar kinds of analyses.
       The commenter presented a brief history of the growing
  expertise on global climate change and the current view of the
  potential for climate change.  Additionally, the commenter
  presented a range of strategies from various national and
  international bodies to address the issue.  The commenter
  included a quote from the Bush Administration's National
           *
  Energy Strategy which listed the proposed regulations as
  recent U.S. activities aimed at reducing greenhouse gas
  emissions.  The commenter concluded that clear scientific
  consensus exists about the severity of the impact of
  greenhouse gases and global climate change.  The commenter
  disagreed with the EPA's decision that the uncertainty as to
  the rate and magnitude of possible climate change was a reason
  not to regulate methane.  The commenter argued that the EPA
  had inappropriately not considered recent NOAA experiments
  indicating that the role of methane in global climate change
  has been understated by approximately 25 percent.  The
  commenter cited a paper which proposed that "MSW landfill
  methane reduction is one of the potentially most economical
  ways to...reduce greenhouse gas problems..."
       Another commenter  (IV-F-6) recommended that the control
  of landfill emissions should be based on methane, which would
  allow for establishing tax credits for recovery equipment,
  force utilities to pay a reasonable price for alternative
  energy, and allow for a methane recovery tradeable credit
  system to be developed.
       One industry commenter  (IV-D-27) supported the Agency's
  decision not to consider methane reduction directly in the
  selection of BDT, noting, however, that the methane reductions
  occurring indirectly from the proposal are significant.  The
  commenter said that the EPA  is currently  investigating methane
  reduction, and will be  in a  better position to determine if
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   additional control of MSW landfills is  warranted after these
   investigations are completed.
        Another commenter (IV-D-29)  wanted only the ancillary
   benefits of methane to be considered since  NMOC are the real
   focus of the proposed regulation.
        Two commenters (IV-D-26,  IV-D-33)  wanted a .separate
   methane standard to be developed  to more completely address
   the health and environmental effects of methane.  One of these
   commenter.s (IV-D-26)  stated that  a methane  standard would help
   to control both the individual and aggregate effects of
   methane from landfills and help to address  concerns such as
   global warming.   Another commenter (IV-D-33)  argued that NMOC
   are not an adequate surrogate for methane emissions and that
   methane merits its own standard according to section ill of
   the CAA,  which states that standards be established for
   sources which may endanger public health or welfare.   The
   commenter cited several reasons methane poses a danger to
   humans and to the environment,  including methane's role in
   global warming,  ability to form ozone in the troposphere,
   ability to explode and emit odors,  ability  to transport toxic
   NMOC to the air and landfill surface, and negative effects on
   soil and vegetation.   The commenter suggested using the same
   tier system approach for determining when controls need to be
   applied that is used for NMOC under the proposed regulation.
   The commenter advised the EPA to  disregard  the scientific
   uncertainties associated with the effects of methane on global
   warming and to formulate a separate methane standard to the
   final regulation.
        Response;   In setting standards and EG which reflect BDT
   under section 111 of the CAA,  the EPA considered reductions of
   NMOC directly and methane reductions as an  ancillary benefit.
   The NMOC was selected as a surrogate for MSW landfill
   emissions because NMOC contains the landfill air pollutants
   posing more concern,  due to their adverse health and welfare
   effects.   In addition,  reducing NMOC concentrations in LFG
   will significantly reduce the amounts of methane contained in

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  LFG.  It is estimated that the NSPS will reduce methane
  emissions by 3.9 million Mg on a NPV basis and the EG will
  reduce methane emissions by 47 million Mg on a NPV basis.  The
  U.S. Climate Change Action Plan, released in October 1993,
  contains a series of actions to reduce emissions of methane
  from landfills and other sources.  The Climate Change Action
  Plan forms the cornerstone of the U.S. National Action Plan
  required by the Framework Convention on Climate Change, which
  the U.S. signed in 1992.  The EPA actions to reduce emissions
  of methane and other greenhouse gases will be guided by the
  directives contained in the Action Plan.  Therefore, the EPA
  maintains that no separate BDT for methane is needed at this
  time.
       Methane reductions have been quantified and considered as
  an ancillary benefit of NMOC reductions within these
  regulations.  Furthermore, the nationwide impacts analysis was
  revised for the final regulations to incorporate the economic
  effects of the use of combustion devices that achieve energy
  recovery to comply with the standards.  Since the feasibility
  of energy recovery is dependent on methane, incorporating
  energy recovery into the national impacts analysis does
  increase the influence of methane on the selection of the
  final NSPS and EG.  The use of energy recovery did not change
  the final decision, however, because on a national basis it
  was not more cost effective than flares.  See section 2.18.2
  for a discussion of this decision.  The details of the revised
  analysis are presented under section 1.3.2, "Revisions to the
  Modeling Methodology" in chapter 1 of this document.  The EPA
  has developed a Landfill Methane Outreach Program to lower
  barriers to landfill gas energy recovery and to encourage more
  widespread utilization of landfill gas as an energy source.
  Information regarding the program can be obtained by calling
  the Landfill Outreach Program Hotline at  (202) 233-9042.
       Comment;  One commenter  (IV-D-17) felt the regulation
  should focus on reducing methane emissions from larger
  landfills while encouraging reuse, recycling, and composting

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   in order to reduce methane emissions from smaller MSW
   landfills.
        Response;   These regulations focus on large emitters,  and
   although these are often larger landfills,  some smaller MSW
   landfills may warrant control based on NMOC emission rates.
   These regulations, although based on NMOC emissions, will
   achieve significant reductions in methane emissions.  The EPA
   is encouraging the use of source reduction methods such as
   reuse,  recycling and composting through various programs, and
   such programs are being adopted at the State level as part of
   an overall waste reduction strategy.  Because of the
   variability of economic impacts resulting from source
   reduction activities,  the EPA considers the state and local
   level the appropriate place to make decisions on recycling and
   composting at this time.  See the report, "The Solid Waste
   Dilemma:   An Agenda for Action," (EPA/530-SW-89-019;
   February 1988)  for a more thorough discussion of the EPA's
   overall solid waste policy.  As discussed in the preamble to
   the final RCRA regulation (56 FR 50978; October 9, 1991), the
   EPA has begun a number of initiatives to expand recycling
   efforts,  including:  market studies, federal recycling
   procurement guidelines, the development of training materials
   for State and local recycling coordinators,  publications
   (i.e.,  composting), and the establishment of a National
   Recycling Institute.   The institute is comprised of business
   and industry representatives and will address recycling
   issues.
   2.18.2   Consideration of Energy Recoveryl3
        Comment:   One commenter (IV-L-3)  contended that the cost
   analysis did not consider that many areas of the country have
   strict  air regulations which would require air emission
   control equipment to be installed on an energy recovery
   system,  rendering an energy recovery project uneconomical.
        Response:   The cost analysis estimated the cost of
   installing flares at all landfills above the design capacity
   and emission rate cutoff,  as well as the cost of energy

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  recovery devices.  There are many factors that play a role in
  the use of energy recovery that were not considered in the
  nationwide impacts analysis because of limited resources and
  because the impact of many of these factors cannot be
  accurately quantified.  The selection of energy recovery is a
  site-specific economic decision, and therefore, the EPA will
                                                  •«
  not mandate energy recovery within these standards.  An owner
  or operator will have to consider whether applicable rules
  will render an energy recovery project uneconomical for their
           •
  particular landfill.
       Comment;  One commenter  (IV-D-24) asserted that the EPA
  should attribute some value to energy recovery in the
  selection of the emission rate cutoff.  The commenter argued
  that not to give energy recovery a value is to arbitrarily
  assume it will have no cost impact.  The commenter further
  recommended that some specific provisions addressing energy
  recovery (e.g., requirements to perform feasibility studies if
  control is required) be included in the final regulations.
       Two commenters (IV-D-21, IV-D-33) suggested that energy
  recovery technologies also be defined as BDT, and at the very
  least that additional language be added to the regulation and
  guideline to strongly endorse and encourage energy recovery.
  One commenter  (IV-D-21) further suggested that the cost
  analysis be revised to incorporate the role of energy
  recovery.
       Several commenters wanted energy recovery to be promoted
  through this NSPS in some form.  Three commenters  (IV-D-18,
  IV-D-20, IV-D-50) supported some form of the "Energy Recovery
  Option 2" discussed in the proposal preamble.  Two of these
  commenters  (IV-D-20, IV-D-50) suggested elimination of the
  public meeting provisions requirement.  One of these
  commenters  (IV-D-20) claimed Option 1 fails to explore energy
  recovery or to encourage pollution prevention at MSW
  landfills.  The commenter supported a modified Option 2 which
  would require  landfill operators to examine pollution
  prevention cost-effectiveness in hopes of compelling all MSW

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   landfills to consider energy recovery systems.   The commenter
   recommended including an energy recovery analysis with the
   permit application as an alternative.  The commenter stated
   that publicly-owned landfills may overlook the  benefits of
   energy recovery in order to save money now instead of
   investing in the future.
        The second commenter (IV-D-50)  also supported Option 2,
   provided that the public hearing was eliminated,  but cautioned
   that any specific energy recovery requirement could result in
            •
   a relatively inefficient, higher cost energy conversion
   technology replacing a more efficient, lower cost energy
   technology (i.e., natural gas-fired  generation).
        Another commenter (IV-D-33)  suggested that a combination
   of energy recovery Options II and III be adopted.  The
   commenter recommended that landfill  operators perform energy
   recovery potential analyses as required in Option III and that
   they be required to install an energy recovery  system if the
   analysis produces at least the potential for the owner to
   break even.   The commenter suggested that if the analysis is
   found to be conflicting, the analysis should be discussed at a
   public meeting to see whether installation of an energy
   recovery system should be required.   The commenter asserted
   that energy recovery would offset control costs,  decrease
   fossil fuel use,  and reduce global warming and  acid rain
   effects.   The commenter noted that many landfills already have
   gas collection infrastructures in place to aid  in energy
   recovery and they urged the EPA to consider these factors in
   the cost evaluation of energy recovery.
        One commenter (IV-D-26)  expressed support  for the EPA's
   selection of Energy Recovery Option  I.  The commenter agreed
   with the EPA that energy recovery can be a financial risk due
   to the variability of markets for gas use,  the  difficulty of
   predicting reliable gas production rates,  and discrimination
   against the use of LFG by utilities.   The commenter urged the
   EPA to pursue energy recovery by reviewing State and Federal
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  tax  laws and regulations, and by  expanding methane recovery
  "credit systems."
       One industry commenter  (IV-D-27) supported the Agency's
  decision to leave the evaluation  of energy recovery up to  the
  owners and operators of each site, and not to consider the
  cost impacts of energy recovery in selecting the  level of  the
  standard.
       One commenter  (IV-D-50) asserted that important topics
  such as system availability and reliability and backup flare
           *
  systems for use during outages had been excluded  from the
  proposal BID discussion of energy recovery.  The  commenter
  disagreed with the  EPA's turbine  operation estimate and noted
  that LFG is very highly corrosive with a high potential to
  contaminate lubricants.  The commenter did, however, support
  the  requirement of  the analysis,  noting that if energy
  recovery is economic, it should proceed under local laws and
  regulations.
       Other commenters suggested energy recovery should be
  encouraged through  tax incentives (IV-D-11), ease of
  permitting  (IV-D-19), requiring utilities to purchase
  recovered energy at retail prices (IV-D-11, IV-D-36) or
  compliance extensions for MSW landfills with energy recovery
  systems in place  (IV-D-43).  One  of these commenters  (IV-D-43)
  said the proposed regulation  (which requires a gas collection
  system that reduces NMOC by 98 percent) acts to discourage gas
  mining as an energy recovery option.  The commenter suggested
  that the regulation be amended to include a more  flexible
  guideline for those landfills with gas recovery systems.   The
  commenter also suggested that landfills that employ gas
  control systems which recover the gas for use should be given
  a less stringent air emissions reduction standard.
       In response to the EPA's request for comments regarding
  incorporating climate change considerations in the cost
  analysis and proposals, one commenter  (IV-D-21) recommended
  that the EPA include methane and  CO2 emissions reductions
  obtained through energy recovery  under the regulation and

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   guideline.   Another commenter (IV-D-19)  indicated that some
   form of incentive for energy recovery in the regulations would
   be advantageous.   Still another commenter (IV-D-17)  supported
   the evaluation of methane collection for energy recovery.
        Another commenter (IV-D-29),  stated that the EPA was
   correct in leaving the decision to pursue energy recovery to
                                                   • %
   the owner or operator and not to include energy recovery in
   the BDT decision because of the difficulty in knowing how much
   LFG will be generated and whether a market for it will be
            •
   available.
        One commenter (IV-D-17) indicated that EPA-funded
   contracts should be awarded to research methods for removing
   CO2 from MSW landfills to have purer methane gas.   Another
   commenter (IV-D-19)  suggested resource recovery facilities as
   another viable form of energy recovery.
        One commenter (IV-D-21) was concerned about the quality
   of gas leaving the landfill site for sale.  The commenter
   stated that untreated LFG in a pipeline could pose a human
   health risk and that pipeline systems would be subject to
   rigorous permitting and operational requirements.   The
   commenter also stated that not all LFG will have the necessary
   properties  for efficient combustion.  Because of these
   concerns, the commenter recommended that the EPA provide
   guidelines  on the gas quality necessary for LFG to be
   transported in pipeline systems.   At the very least, the
   commenter requested that the EPA require landfill owners and
   operators to be subject to RCRA since they are hazardous waste
   generators.   The  commenter asserted that this would safeguard
   natural gas companies and end-users.
        Response:  The EPA continues  to consider that the use of
   energy recovery should be a site-specific decision.   Such a
   decision should be made after the  landfill owner or operator
   considers the potential savings given the uncertainty and risk
   for that particular landfill.   Many variables come into play
   when considering  energy recovery,  such as gas market
   fluctuations,  gas production rates,  and the quality of the

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  gas.  For this reason, the EPA will not mandate energy
  recovery within these standards.  The use of resource recovery
  facilities is a solid waste issue, and the focus of this
  regulation is on air emissions from landfills.
       The EPA is not requiring an energy recovery feasibility
  analysis because the EPA does not consider such an analysis
                                                   • %
  appropriate as part of an NSPS.  The EPA still considers the
  selection of energy recovery to be a site-specific economic
  decision, rather than a pollution control decision within the
            •
  purview of section ill of the CAA.  The EPA can, however,
  promote energy recovery by discussing it in the preamble and
  showing its benefits by including the use of energy recovery
  in the nationwide impacts analysis.  The potential for cost
  savings via energy recovery for those landfills subject to
  this regulation is discussed in section 1.3 of chapter 1 of
  this document, and outreach efforts are described in
  section 1.2.1.4 of chapter 1.
       The EPA decided to incorporate energy recovery in the
  nationwide impacts analysis by adding an energy recovery
  analysis to the original flare analysis upon which the
  selection of BDT is based.  For this second analysis, the
  nationwide impacts analysis was modified to select the
  least-cost of three control options for each model landfill:
  flares, I.e. engines, or turbines.
       It was determined that using energy recovery systems is
  generally more cost effective at larger landfills; however, on
  a nationwide basis energy recovery did not prove to be
  significantly more cost effective than flares.  The reason  for
  this is that it was estimated that most landfills using energy
  recovery  systems will do so in the absence of the regulation,
  and such  landfills were not included in the nationwide impacts
  analysis.  The revised nationwide impacts are detailed in the
  memorandum "Revised Nationwide Impacts for Development of
  Regulatory Alternatives," June 4, 1993, (Docket No. A-88-09,
  Item No.  IV-M-7).
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        Comment;   One commenter (IV-D-11)  provided data on fuel
   cell operation and stated that the regulation should promote
   energy recovery by requiring that the methane captured with
   NMOC be used for electricity by using fuel cells (not
   combustion).   Because fuel cells emit only low levels of air
   pollutants,  the commenter suggested that the fuel cell be
   listed as BACT.  The commenter maintained that the proposed
   standard should require energy recovery equipment to meet air
   emissions standards comparable to those of SCAQMD
   Regulation 1110.2 and SCAQMD proposed regulation 1135.  The
   commenter also suggested that the regulations should require
   that methane be converted to electric power on government
   lands.
        One commenter (IV-G-2)  supported all comments submitted
   by Commenter IV-D-11.  The commenter agreed that the EPA's
   regulations  should require that methane collected in
   conjunction  with the collection of NMOC not be combusted, but
   be used for  electric power production.   The commenter
   supported listing the fuel cell as BACT noting that this would
   allow energy recovery at MSW landfills in the most efficient
   and environmentally safe manner.
        Response:  The use of fuel cells is currently being
   investigated by the AEERL of the EPA.  While this technology
   looks promising,  the EPA's investigation will not be completed
   in time to evaluate whether fuel cells could be listed as BDT
   within these regulations.  As more information becomes
   available, however, an owner or operator could submit a
   collection and control plan incorporating the use of fuel
   cells.   The  EPA considers the selection of energy recovery to
   be a site-specific economic decision and will not mandate
   energy recovery within these standards.  The EPA encourages
   the use of energy recovery methods,  including fuel cells,
   where it is  feasible and cost-effective.
        Comment;   One commenter (IV-L-2) recommended that energy
   recovery be  required under the NSPS and that the offsetting of
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  utility emissions by the generated energy be included in the
  economic analysis of the NSPS.
       The commenter  (IV-L-2) included a figure showing that
  greenhouse gas emissions are higher at a facility using energy
  recovery compared to a waste-to-energy facility and are higher
  when no energy recovery is used.  The commenter (IV-L-2) also
  said the figure disregards the offsetting of emissions from
  utilities or other  sources that would be reduced because of
  energy recovery at  landfills which can amount to a significant
  abatement of utility emissions.  The commenter also referred
  to Titles I and IV  as subjects of Congressional attention
  regarding significant abatement of utility emissions.
       Response;  The EPA continues to consider the use of
  energy recovery a site-specific decision, and will not mandate
  it within these standards.  For further information on
  comments received on this subject in response to the proposed
  rule and the EPA's  response, see the memorandum "Analysis on
  Landfill Gas utilization for the Soon-to-be Promulgated Clean
  Air Act Regulations for Municipal Solid Waste Landfills,11
  September 14, 1993  (Docket No. A-88-09, Item No. IV-B-5).
       Comment;  One  commenter  (IV-L-7) disagreed with the
  regulation's failure to credit the value of avoided
  environmental externalities  (reducing global warming, local
  air pollution problems, and dependance on foreign suppliers of
  fuel) associated with energy recovery in the comparison
  between energy recovery and flaring.  The commenter  (IV-D-7)
  compared energy recovery and flaring, stating that energy
  recovery avoids the need to use costly fossil fuel to produce
  energy and does so  without adding additional pollution to the
  atmosphere.  The commenter  (IV-D-7) contended that these
  benefits can not be ignored and an emission standard should be
  judged by how well  it prevents total pollution, not solely by
  how cost effective  it is to install a technology relative to
  less effective alternatives.  The commenter  (IV-D-7) stated
  that the EPA should require energy recovery so  long as it  is
  cost effective when compared to avoided energy  and capacity

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   costs of the electric system along with the associated
   environmental costs.
        Response;   There are many factors that play a role in the
   use of energy recovery that were not considered in the
   nationwide impacts analysis; some are site specific while
   others, those mentioned by the commenter,  are national
   factors.  A more rigorous review of these  factors was not
   performed because of limited resources and because the impact
   of many of these factors cannot be accurately quantified.
   However, the reduction in fuel usage at electric utilities was
   reflected to varying degrees in the buy-back rates used in the
   energy recovery modeling.  Also, the purpose of the least cost
   option in the nationwide impacts analysis  was to estimate the
   number of landfills that would potentially choose energy
   recovery because of economics and then estimate nationwide
   impacts based on the control devices predicted to be applied.
   Requiring energy recovery as the control device is not
   appropriate because it is a site-specific  decision.  There is
   an element of risk that owners or operators take to use energy
   recovery and it is not successful in all cases.  Although
   there are national benefits that may occur when a facility
   uses energy recovery,  it is not in the best interest of
   landfill owners or operators,  or the nation to require
   facilities to use energy recovery and face the economic risk
   of a nonproductive landfill.  These decisions are better made
   on a site-specific basis.  The NSPS emission limits in the
   standard are based on use of BOT as required by section 111 of
   the CAA.  The owner or operator should have the flexibility to
   use any control technique that can meet the specified control
   levels.  Section 1.3  of this document estimates some of the
   national benefits of  using energy recovery, such as reducing
   the fuel used by utilities.
        Cgiflflient•   One commenter (IV-L-3)  maintained that the cost
   of a flaring system should have been included in the energy
   recovery system cost.   The commenter . (IV-L-3)  stated that an
   energy system does not operate for the full gas generation

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   life span and  flares are needed at the beginning  and  at  the
   end of  landfill operation when gas generation  is  lower.  The
   commenter  (IV-L-3) stated that flares are needed  as excess
   flow control systems.  The commenter  (IV-L-3)  also stated that
   flares  are also needed at least 20 percent of  the total
   control time when gas production  levels decrease  and  energy
                                                  • \
   recovery systems are inefficient  at partial loads.
       Response:  The EPA agrees that energy recovery will most
   likely  not be  used throughout a landfill's gas generation
           •
   life; however, this assumption was made in order  to simplify
   the analysis for the least cost option.  Therefore, the  cost
   estimated for  a landfill using energy recovery is
   overestimated  since it was assumed that energy recovery
   equipment  (I.e. engine or turbine) would be used  from the
   beginning to the end of the  control period at  the landfill.
   In reality, as the commenter pointed out, a less  costly  flare
   would most likely be used at the  beginning and the end of the
   control period.  The effect  of this cost overestimate is that
   fewer landfills are estimated to  use energy recovery  than the
   actual  number  of landfills that could benefit  from using
   energy  recovery if the control system was switched during the
   control period of the landfill.
       The flare system used at the beginning and the end  of the
   control period would also be used as a backup  in  times of low
   gas flow and partial loads to the energy recovery system, and
   in times when  there is excess flow.  The overestimated cost
   due to  assuming that the landfill would use energy recovery
   for the full control period  is assumed similar to the cost of
   a back-up  flare system throughout the control  period  with
   energy  recovery control devices.
       Comment;  One commenter (IV-L-3) supported the EPA's
   attempt to eliminate the bias of  landfills that would develop
   gas to  energy  systems in the absence of the rule. However,
   the commenter  (IV-L-3) maintained that the data base  still
   contained  anomalies other than those specifically identified
   by the  EPA.  The commenter  (IV-L-3) further stated that  it  is

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   impossible to eliminate all biases and that future gas to
   energy projects may be influenced by factors similar to those
   the EPA is attempting to remove.   For these reasons, the
   commenter (IV-L-3)  recommended that the data base not be
   modified and that it include all  projects.   The commenter
   (IV-L-3) stated that the increase of the energy buyback rate
   in New Jersey, New York, and Pennsylvania brings in a
   potential bias.
        The commenter (IV-L-3) stated that the EPA has deleted
   California gas-to-energy projects in the data base to reduce
   bias.   The commenter (IV-L-3)  stated that the bias is
   attributed in part to ISO No.  4 contracts from California
   utilities in 1984 and 1985, creating a favorable energy sales
   base.   The commenter (IV-L-3)  contended that a number of
   energy projects would have likely proceeded even without the
   contracts and the fact that the contracts were withdrawn does
   not necessarily indicate that the trend would not continue.
        The commenter (IV-L-3) also  stated that the EPA
   attributes bias in California to  the SCAQMD landfill emission
   rule.   The commenter (IV-L-3)  asserted that the effect of the
   landfill emission rule is unclear because it falls within the
   same period that ISO No. 4 were in effect.   The commenter
   (IV-L-3) noted that 11 facilities implemented gas to energy
   projects in a similar number of years prior to either rule.
        The commenter (IV-L-3) concluded that deleting California
   projects will reduce bias and that eliminating them may
   introduce a new bias into the data base and make it less
   representative of future trends.
        Response:  The commenter has confused the analysis to
   predict how many energy recovery  projects will be in place in
   the future in absence of the rule (138 landfills; as described
   in the memorandum entitled "Landfill Rule Energy Recovery Cost
   Analysis,  December 16,  1992, Docket No.  A-88-09, Item
   No.  IV-M-2)  with the deletion of  the landfills estimated to
   use energy recovery in absence of the rule from the landfill
   data base.   The attempt to eliminate bias discussed by the

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  commenter was actually done in two analyses; however, the
  commenter confuses it as being one analysis.  The intent was
  to eliminate the bias of landfills that would develop energy
  recovery systems in absence of the rule from the landfill data
  base.  See the memorandum "Changes to the Municipal Solid
  Waste Landfills Nationwide Impacts Program Since Proposal,"
  April 28, 1993, (Docket No. A-88-09, Item No. IV-M-3).  In
  order to obtain this goal, an analysis had to be performed to
  determine, how many landfills would develop the energy recovery
  systems in absence of the rule.  In this analysis the National
  trends in landfill energy recovery were reviewed.  The EPA
  determined that, in order to use the trends as a predictor of
  the future, bias had to be eliminated for special projects in
  California, such as ISO No. 4 and the SCAQMD rule.  The energy
  recovery projects associated with ISO No. 4 were deleted from
  this analysis as a reasonable estimate for the bias from both
  ISO No. 4 and the SCAQMD rule, because some of the ISO
  projects would have been developed anyway.  The increase in
  energy buyback rates in New Jersey, New York, and
  Pennsylvania, mentioned by the commenter, does not introduce a
  bias because these rates will fluctuate over time as they did
  in the timeframe used to predict the future energy recovery
  projects.  Also the increased buyback rates will continue to
  affect future energy recovery projects.  This analysis
  concluded that a yearly average of 138 landfills would apply
  energy recovery in the absence of an NSPS.
       As a separate step, because 138 landfills would apply
  energy recovery in the absence of the rule, the 138 most
  profitable landfills in the data base were removed from the
  analysis to estimate the national cost and emission reduction
  impacts.  As explained in a previous response, it would be
  inaccurate to attribute costs and emission reductions for
  these landfills to the rule.
       Comment;  In regards to the analysis to determine the
  number of gas to energy sites in the future, one commenter
   (IV-L-3) asserted that a few operators of many landfills

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   dominate gas to energy projects and could be viewed to bias
   the data base.  The commenter (IV-L-3)  maintained that
   60 percent of all landfill gas is recovered for energy
   purposes by just three operators.  The  commenter (IV-L-3)
   stated that the large operators achieve a large economy of
   scale because of their size and expenditures with^ vendors and
   service companies.
        Response:  The commenter implies that there is a bias due
   to landfall owners  or operators that have developed a large
   economy of scale for energy recovery equipment and service,
   and that this bias  affects the analysis used to determine the
   number of landfills that would use energy recovery in the
   absence of the standard.  If there is such a bias, the number
   of landfills predicted to install energy recovery in absence
   of the standard would be overestimated  and the current
   nationwide impacts  would be underestimated.  On the other
   hand,  if in reality fewer owners and operators would develop
   energy recovery systems in the absence  of the standard, then
   more energy recovery systems would be developed because of the
   standard and the cost-effectiveness of  the standard would be
   lower.   In this scenario,  the current nationwide impacts would
   be overestimated.
        Since the cost information for energy recovery operations
   was obtained from several sources,  the  likelihood of either
   scenario has been minimized.   In other  words,  the cost
   estimates were based on cost data associated with operators of
   many landfills as well as operators of  few landfills.  Since
   the operators that  maintain the majority of energy recovery
   systems also own a  greater number of landfills,  it can be
   assumed that these  operators will continue to develop more
   energy recovery systems at their other  landfills than smaller
   landfill operators.   Therefore,  bias in the number of
   landfills installing energy recovery and the nationwide
   impacts should be minimized.
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  2.18.3  Consideration of Materials Separation
       g9lpmgr)i-?  Two conunenters  (IV-D-18, IV-D-33) supported the
  inclusion of materials separation in the NSPS.  One commenter
  (IV-D-33) stated that reducing the amount of waste landfilled,
  especially organic wastes, would decrease LFG emissions.
  However, materials such as glass, metal, and plastics, which
  contribute less to gas emissions, may be better regulated
  under RCRA.  Six commenters  (IV-D-19, IV-D-22, IV-D-26,
  IV-D-27, -IV-D-29, IV-D-39) agreed with the EPA's decision not
  to include such provisions.  Seven commenters  (IV-D-25,
  IV-D-26 and IV-F-6, IV-D-27, IV-D-29, IV-D-34, IV-D-39 and
  IV-F-3, IV-D-50) noted that RCRA was the proper authority for
  such requirements.  One of these commenters  (IV-D-27) included
  the arguments it had prepared  in opposition to proposed
  materials separation provisions for MWC's.
       One commenter (IV-D-26) suggested that the EPA wait for
  the RCRA reauthorization before proposing any type of
  municipal landfill materials separation requirement.  The
  commenter recommended that the EPA take into consideration the
  widespread changes a national  materials separation regulation
  will cause to the economy and  the industrial sector.  In
  addition, the commenter urged  the EPA only to consider the
  issue of materials separation  as it relates to landfill air
  emissions, and to explore ways to manage nonhazardous solid
  waste in a more comprehensive  way.
       One commenter (IV-D-19) stated that some method of
  segregating toxic substances  (such as batteries) in the waste
  stream needed to be implemented.  A second commenter
  (IV-D-12), representing a trade association, stated that
  80 percent of lead produced  in the U.S. is used in lead-acid
  batteries and that 90 percent  of these batteries are recycled.
  A third commenter  (IV-D-17)  recommended the evaluation of
  reuse and recycling programs.  Another commenter  (IV-D-39)
  stated that there are no data  that they are aware of that
  quantify emission reductions afforded by a materials
  separation and removal requirement.

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        Response:   The EPA continues to consider RCRA the
   appropriate regulatory framework for material separation.   The
   final RCRA preamble identified an array of initiatives
   designed to expand recycling efforts (56 FR 50980;
   October 9,  1991).   These initiatives include market studies,
   federal recycling  procurement guidelines,  the development  of
   training materials for State and local  recycling coordinators,
   publications,  and  the establishment of  a National Recycling
   Institute,.
   2.19 MISCELLANEOUS
        Comment:   One commenter (IV-D-9) requested that the EPA
   form a technical advisory group to assist in the writing of
   "more realistic" regulations.  The commenter reported that
   such groups are being used successfully in Florida.
        Response;   In developing the proposed standards, the  EPA
   worked closely with organizations such  as NSWMA, SWANA,
   SCAQMD,  WMA, BFI and other government and industry
   representatives.  Information regarding meetings and
   correspondence with these participants  is documented in  the
   docket (A-88-09).   The proposed regulation is the result of
   the knowledge,  expertise and data provided to the EPA by those
   organizations  directly affected by the  standards.   Comments on
   the proposed standards submitted by these groups and other
   commenters have been carefully considered and the EPA has  made
   appropriate changes to the final regulations.  Therefore,  the
   EPA believes the regulation is realistic and has not formed a
   technical advisory group for use in writing these regulations.
        Comment;   One commenter (IV-D-9) was in agreement with
   all the public hearing comments.   The commenter stated that
   there are major problems in all areas of the draft regulation:
   cost/benefit,  health risk,  field management of migration and
   surface emissions  versus empirical modeling,  design
   specifications versus performance standards,  operational
   requirements,  and  other aspects.
        Response;   The EPA response to specific comments from the
   public hearing are provided in section  2.2.1 on health

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  concerns, section 2.8.3 for discussion of the  cost-benefit
  analysis, sections 2.10 and 2.11  for modeling  issues,  2.12 for
  design specifications, and 2.13 for operational  standards.
       Comment;  Five commenters  (IV-D-1,  IV-D-13,  IV-D-15,
  IV-D-40, IV-D-57) requested that  the comment period  be
  extended an additional 30 to  90 days to  allow  tim,e for
  additional comments on the proposed regulation.
       Response;  The typical comment period  for an EPA
  rulemaking involving complex  subjects under the  CAA  is
  60 days.  The Administrator determined that a  longer comment
  period was not necessary, but stated that the  EPA would
  consider all comments received  in a timely  manner.
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                       3.0  ECONOMIC IMPACTS
                                                   •«
       This  chapter  evaluates  the  economic  impacts of  the
   Slll(d) Guidelines and  §111(b) Standards  under  the Clean Air
   Act  (CAA) 'that  EPA has  proposed  for  closed/existing  and new
   landfills.  We  have reviewed and made  changes in our analysis
   since  the  original draft  report, "Economic  Impact  Analysis of
   Air  Emissions Controls  on Municipal  Solid Waste Landfills"
   submitted  November 1989.
       The following topics are addressed in  this chapter:
       •  waste generation and disposal as it is now practiced;
       •  requirements of promulgation and recordkeeping;
       •  characteristics and control periods of affected
         landfills under present assumptions and engineering
         models;
       •  net present value  (NPV) of enterprise costs and the
         costs per megagram (Mg) and per household;
       •  costs to society (annualized and net present value);
       •  emissions reductions and cost effectiveness; and
       •  summary of analysis,  comparison of final rule options
         with proposed rule options,  and conclusions.
       In addressing these  topics, we  have  revised some of the
   underlying assumptions  concerning quantities of waste to give
   better estimates of the waste flow going  to landfills.
   Impacts computed for the  proposed rule options  analysis were
   estimated  based on data reported in  the Office  of  Solid Waste
   (OSW)  Landfill  Survey.1'2  The 1986 waste  flow going  to
   landfills  reported in the survey was a particularly  important
   variable in determining compliance costs  and emission
   reductions.  However, using  the  OSW  landfill data  to analyze

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  impacts under the proposed rule options posed two problems.
  First, some landfills reported their waste acceptance rate in
  cubic yards, thereby creating a conversion problem from cubic
  yards to tons.  We had to assume a density factor for cubic
  yards of waste accepted by these landfills to standardize
  these values to tons of waste landfilled.  The second
  difficulty involved differences between the reported
  historical acceptance rates  (pre-1986) and the 1986 acceptance
  rate.  The resolution of these problems for the analysis of
  the proposed rule resulted in a total municipal solid waste
  (MSW) acceptance rate that was a substantial overestimate of
  the national MSW generation.  For the analysis of the final
  rule options, we computed impacts using a revised (lower)
  estimate of the landfill acceptance rate.
       In addition, several changes were made to the engineering
  model to give better estimates of the costs of the proposed
  regulation.  We also incorporated these changes into the
  economic impacts analysis of the final rule options.  The
  following sections discuss the results from the revised models
  and cost calculations.
  3.1  OVERVIEW OF MUNICIPAL SOLID WASTE MANAGEMENT
  3.1.1  Waste Generation
       MSW is generated as a by-product of consumption and
  production.  Generated waste is collected and transported to  a
  centralized location.  After collection, MSW is either
  directly landfilled, incinerated in a municipal waste
  combustor, or sent to a centralized recycling facility.  Most
  recycling and combustion residues are also sent to landfills.
       MSW management uses two types o.f landfills:  hazardous
  waste landfills that receive both hazardous and nonhazardous
  wastes and sanitary landfills.  Sanitary landfills receive
  nonhazardous wastes from residential, commercial, and
  industrial sources and small amounts of hazardous waste
  generated by small quantity generators.  In this report, we
  are concerned with sanitary  landfills.


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        EPA's  Office of  Air Quality Planning  and Standards  is
   developing  air emissions for  closed/existing  landfills under
   §111(d)  and new municipal landfills  under  $111(b)  of  the CAA.3
   The  CAA  regulations will limit  air emissions  of  nonmethane
   organic  compounds (NMOC),  air toxics,  odors,  carbon dioxide,
   methane,  and other explosive  gases from landfills." The
   regulation  will require the active collection and  disposal  of
   air  emissions.
   3.1.2 Waste Disposal
        Haste  is disposed in sanitary landfills  through  a
   three-step  process that includes
       • spreading collected waste into thin layers  in the
         landfill,
       • compacting the  layers  into the smallest practical
         volume, and
       • covering the compacted waste with soil on a daily
         basis.
        After  waste is deposited in the landfill,  it  immediately
   begins to decay,  producing several gaseous by-products  in the
   process.  Landfill waste digestive processes  are aerobic
   (i.e., they occur in  the presence of free  oxygen)  until  nearly
   all  the  oxygen in the waste is  consumed.   Waste  decomposition
   then changes to an anaerobic  process (i.e., a process that
   occurs in the absence of free oxygen).   Gases produced by
   decomposition migrate through landfilled waste and disperse
   into the atmosphere unless emission  controls  are implemented.
        Methane gas generated by MSW is a greenhouse  gas.   It  is
   not  addressed in this report  because it is not a volatile
   organic  compound (VOC) precursor and is not considered
   hazardous to human health in  the same manner  as  a  carcinogen.
   Methane  is  counted in the benefit-cost analysis, but  the
   impetus  for the proposed guidelines  and standards  was VOCs  and
   hazardous air pollutants (HAPs). Therefore,  we  will  only
   address  nonmethane organic compound  (NMOC)  generation in this
   report.   These compounds are  VOC precursors or HAPs.

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       Throughout this report, we discuss both new and
  closed/existing landfills.  New landfills are assumed to be
  exactly like comparable landfills that closed during the time
  period of this study.  For the purposes of this study, we
  assumed that, for every landfill that closed during the time
  period, one exactly like it opened.               *
       As Figure 3-1 illustrates, NMOC generation begins slowly
  as soon as waste is deposited in landfills and increases over
  several years.  Gas generation continues for an extended
  period of time after landfills are closed and then begins to
  taper off.  Emission controls are required when NMOC emissions
  reach a specified cutoff level.  Controls must remain
  operational until gas emissions decline again to the cutoff
  level as gas production tapers off.
       The control option discussed in this report is flares
  (combustion without energy recovery).  We assumed all affected
  landfills choose to control their emissions in this manner,
  although we expect many, if not most, of them would choose
  control options that have some sort of energy recovery feature
  to offset the costs of controlling emissions.  This assumption
  overestimates the actual costs of the regulatory alternatives
  because the flare option assumes there are no offsetting
  revenues.  The flare option is, therefore, the most
  conservative assumption.
  3.1.3  Requirements of Alternatives for Promulgation
       The requirements of alternatives for promulgation of the
  regulation consist of a size cutoff, an emissions  cutoff, and
  recordkeeping requirements.  Landfills affected by the
  regulation are those with 1 million or more megagrams of
  permitted capacity.  Landfills below that size cutoff are not
  expected to be subject to emissions control requirements.
       In this report, EPA has evaluated three potential
  emissions cutoff  levels:  50, 75, and 100 Mg per year  of NMOCs.
  "Affected landfills" are those meeting the emissions  cutoff
  levels either in  pre- or post-closure periods.  In the most
  stringent alternative, EPA  will require emissions  controls on
kli-85\04                           3-4

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      Emissions Produced
      MgNMOC/yr
           Operation of
           Emission Controls
     Operation of
Emission Controls
      May Cease
                                                                       100
   Landfill First
   Accepts MSW
    Years Since Initial
    Refuse Placement
       Figure  3-1.   Affected model  landfill:  Length of control
                 period tinder three stringency levels.
klk/270:BID (05/25/95)
                                     3-5

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  all landfills emitting 50 Mg of NMOCs per year.  Less
  stringent alternatives require controls at 75 Mg and 100 Mg
  per year levels, respectively.  High emissions cutoff levels
  mean that more landfill-generated gas can be released before
  emission controls must be installed and maintained.
  3.2  CHARACTERISTICS OF AFFECTED LANDFILLS
  3.2.1   Design Capacity                           *
       Design capacity refers to the amount of waste that
  landfills are designed to accommodate per year.  Landfills
  affected by the regulations vary considerably by design
  capacity.  Significantly fewer landfills are projected to be
  affected in the final rule option than were projected in the
  proposed rule option (see conclusions).  Since 1989, a
  permitted design capacity cutoff limit of 1 million Mg per
  year has been instituted, and certain engineering parameters
  and assumptions have been revised, resulting in a much smaller
  affected population  (see Appendix A).
       Of the 7,437 landfills subject to §111(d) Guidelines,
  between 4 and 8 percent would be affected depending on the
  stringency level.  As mentioned above, the three possible
  stringency levels examined are releases of 50, 75, and 100 Mg
  NMOC per year.  If the most stringent 50 Mg per year
  alternative were selected, 572 existing and closed landfills
  would be affected.   If the 75 Mg per year cutoff were
  selected, 415 landfills would be affected while only 305
  existing and closed  landfills would be affected if the 100 Mg
  per year cutoff were selected  (see Table 3-1).
       The §111(b) Standards apply to landfills constructed and
  opened after the regulation takes effect.  In this study, we
  assumed these new landfills replace other landfills that
  closed.  Specifically, we assumed that every landfill that
  closes after 1992 is replaced by an identical landfill serving
  the same area.  Recycling and pollution prevention efforts may
  cause reduced local  requirements for landfill space while
  increasing and shifting populations may increase needs.  We
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  realize 'that our assumption concerning new landfills may not
  hold true in every case.
       Mew landfills would also be subject to the regulation.
  Of the approximately 944 new landfills nationwide, 89 would be
  affected by the flare option if the most stringent 50 Mg per
  year alternative were selected.  If the 75 Mg perxyear cutoff
  were selected, 56 landfills would be affected while only 33
  landfills would be affected if the 100 Ng per year cutoff were
           •
  selected (see Table 3-2).
       Tables 3-1 and 3-2 also show affected landfills
  distributed according to design capacity.  In both
  closed/existing and new categories, the greatest number of
  affected landfills are those with the smallest design capacity
  (accepting < 5 Mg per year of waste).  At the 50 Mg per year
  level, 66 percent of the affected closed/existing landfills
  are in the smallest size category.  At the 75 Mg per year
  level, 61 percent are below this size; 53 percent are this
  size at the 100 Mg per year level.  Of new landfills, 82
  percent are in the smallest size category (accepting £ 5 Mg
  per year of waste) at the 50 level, 82 percent at the 75
  level, and 76 percent at the 100 Mg per year level.
       Under all stringency levels, closed and existing private
  landfills constitute a slightly larger percentage of affected
  landfills than was the case before the size cutoff was
  instituted  (27 to 34 percent versus 22 to 31 percent).  Of the
  total closed/existing landfills, 104 are private at the 100
  level, 121 are private at the  75 level, and 154 are private at
  the most stringent emission cutoff level, 50 Mg/yr.  Privately
  held affected new landfills are smaller percentages of the
  total affected landfills at the 75 and 100 Mg per year levels
  and about the same at the 50 Mg per year level.  At  the 50 Mg
  level of stringency, 20 of the affected new landfills are
  privately owned  (Appendix A and Table 3-2), 10 at the 75
  level, and  6 at the 100 Mg/yr  level.  As previously stated,
  landfills expected to have the greatest difficulty paying  for
  NMOC controls are those that are privately owned and already

klk-85\04                            3-8

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3-9

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  closed.  As shown in Table 3-1, at both the 50 and 75 Mg/yr
  stringency levels, 4 percent of the affected landfills are in
  this category while 5 percent of the affected landfills are
  closed and privately owned at the 100 level.
  3.2.2  Control Periods for Affected Landfills
       Landfills will be required to operate emissions controls
  as long as their emissions exceed the selected cutoff level.
  Individual affected landfills will reach the selected
  emissions 'cutoff level in different years, depending on waste
  deposited.  Similarly, the number of years that emissions will
  exceed the cutoff level will vary from landfill to landfill;
  therefore, the year that controls may be removed will also
  vary.  The longer emissions must be controlled, the greater
  the compliance costs and the greater the economic impacts of
  the regulation (see Figure 3-1).
       Tables 3-3 and 3-4 present the length of control period
  for closed/existing landfills and for new landfills,
  respectively.  Average lengths of control periods do not vary
  significantly across stringency levels in either table.
  However, the distributions of landfills by length of control
  period do vary widely from less than 25 years to greater than
  150 years.  However, at all stringency levels, half to three-
  quarters of the landfills have control periods of 50 years  or
  less.
       The ease with which landfills will be able to recapture
  costs of installing and operating controls will decrease after
  each landfill closes.  Until that time, the  landfill may
  increase its user fees to offset some of  its increased costs.
  After closure, landfill owners must find  some other way of
  raising revenues.  Public landfill owners may raise taxes.
  Private landfills can only raise revenues through increased
  user fees while they are still  operating  and accepting MSW.
       Thus, the shorter the length of time between the start of
  controls and landfill closure,  the greater the financial
  burden of a given control on a  landfill especially  if it  is
  privately owned.

klk-85\0*                           3-10

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   3.2.3   Control  Periods  Prior  to  Closure
       Tables  3-5 and 3-6 show  the length  of  control  periods
   prior  to closure for existing and new landfills respectively.
   Existing landfills  average 19.7  years of control prior  to
   closure at the  50 stringency  level,  19.3 years  at the 75
   level,  and 21 years at  the 100 level.  New  landfills average
   12.1 years at the 50 level, 11.5 years at the 75 level, and
   12.7 years at the 100 level.
       Landfills  with the shortest periods of control before
   closure (£5 years)  are those with the greatest economic
   impacts under the regulation  because they have  the  shortest
   time to recover control costs by raising user fees.  Affected
   existing landfills  in this category represent 20, 28, and 15
   percent of the  total affected at the 50, 75,  and 100 Mg per
   year levels, respectively. Affected new landfills  in the < 5
   years  category  are  28,  34, and 29 percent at the three
   respective control  levels (see Table 3-6).
       Table 3-7  shows that affected private  existing landfills
   average 23.9, 25.4,  and 27.5  years of control period prior  to
   closing at the  three stringency  levels.   Of this subset of
   existing landfills  that are presumed to  be  the  most severely
   affected by  the regulation, 17 percent have a control period
   prior  to closure of <5  years  at  the 50 stringency level,  21
   percent are  in  this category  at  the 75 level, and 11 percent
   at  the 100 level.
   3.3 IMPACTS OF THE REGULATION
       We analyzed the economic impacts of the regulation on
   existing and new landfills.   Measures of these  impacts  include
   enterprise costs (the costs to each facility),  social costs
   (the costs to society), recordkeeping costs,  and emissions
   reductions and  cost effectiveness.
klk-85\0«                           3-13

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3-15

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klk-85\0*
                                            3-16

-------
   3.3.1  Enterprise Costs
        In this discussion of enterprise costs,  we address the
   following:
       • NPV of enterprise costs,
       • annualized enterprise costs,
       • costs per Mg of waste and costs per household, and
       • recordkeeping costs.
        3.3.1.1  NPV of  Enterprise Costs.   One measure of  the
   cost of complying with the regulatory alternatives under
   consideration is the  NPV of enterprise costs.  This measure is
   computed by discounting the flow of capital and operating
   costs to arrive at a  measure of the current value of the costs
   that will be incurred throughout the control  periods of the
   various landfills.  Because most landfills will begin and end
   controls at different times,  using an NPV measure of costs is
   an appropriate way to compare costs between landfills.
        Closed/Existina  Landfills.  Table 3-8 presents NPV of
   enterprise costs for  closed/existing landfills.  The interest
   rates faced by public owners of landfills differ from those
   faced by private owners,  so we discounted the stream of
   capital and operating costs using a different discounted rate
   for each ownership group.   We discounted the  capital and
   operating compliance  costs incurred by public landfill  owners
   using a 4 percent rate,  and we discounted costs incurred by
   private landfill owners to their NPV using an 8 percent rate.
   Table 3-8 presents these costs, along with a  distribution of
   the number of  affected landfills in several enterprise  cost
   categories for each of the three stringency levels.
        The maximum NPV  of enterprise costs incurred by any
   closed/existing landfill is $50.3  million under the 50  Mg
   stringency level,  $50.1 million under the 75  Mg stringency
   level,  and $49.8 million under the 100 Mg stringency level.
   When summed across all landfills affected by  controls under
   each stringency level,  the national total NPV of enterprise
   costs  ranges from $1.37  billion under the 100 Mg stringency
   level  to $2.10  billion under the 50 Mg stringency level.

kli-85\04                          3-17

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klk-85\0*
                                          3-18

-------
        NPV of  enterprise  costs varies  from  less than  $500,000 to
   more than $10  million at  all stringency levels.  At the  50 Mg
   NMOC/yr level,  63  percent have  an  NPV of  $3 million or less
   while 57 percent and 48 percent of the landfills at the  75
   level and 100  level, respectively, fall in this category.
        Haw Landfills.  Table 3-9  presents NPV of enterprise
   costs for affected new  landfills.  As shown in the  table,
   89  new landfills affected by the 50  Mg level of control  have
   total enterprise costs  of $212  million, while the 56  new
   landfills affected by the 75 Mg level of  stringency have an
   aggregate NPV  of enterprise costs  of $150 million,  and the 33
   new landfills  affected  by the 100  Mg stringency level have
   aggregate NPV  of enterprise costs  of $114 million.  While the
   aggregate NPV  of enterprise costs  are highest at the  50  Mg
   stringency level,  the average NPV  enterprise cost per facility
   for this level, $2.39 million,  is  lower than for the  other two
   stringency levels  because so many  more landfills with lower
   costs are affected by the 50 Mg stringency level.   At the 75
   Mg  stringency  level, the  average NPV enterprise cost  per new
   facility is  $2.68  million,  while the average NPV enterprise
   cost per facility  is $3.44 million at the 100 Mg stringency
   level.
        The frequency distribution of affected new landfills by
   NPV of enterprise  costs in Table 3-9 indicates that a higher
   proportion of  affected  landfills under the more stringent
   control alternatives experience a  relatively low NPV  of
   enterprise costs.  For  example, under the 50 Mg stringency
   level,  31 percent  of affected facilities  have an NPV  of
   enterprise costs of $1  million  or  less.   Under the  75 Mg
   stringency level,  24 percent have  a  NPV of enterprise costs of
   $1  million or  less, and only 23 percent have a NPV  of
   enterprise costs of $1  million  or  less under the 100  Mg
   stringency level.
        3.3.1.2  Annual!zed  Enterprise  Costs.  The annualized
   enterprise control cost per Mg  of  MSW and the annualized cost
   per household  for  affected existing  landfills are based  on

klk-85\0*                          3-19

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   each landfill's NPV of enterprise costs.  These costs are
   annualized using the following formula:

              Annual!zed NPV of _ NPV (enterprise costs)
              Enterprise Costs "    (i - (i+r)"1) /r)
                                                    •»
   where r is the interest rate and t is time.
        The interest rate and the length of time over which costs
   are annualized depend on the ownership of the landfill.  As
   explained previously, publicly owned landfills are annualized
   using a 4 percent interest rate over the time period during
   which controls will be in place.  Privately owned landfills,
   on  the other hand,  will not be able to recapture their
   compliance costs after they stop accepting MSW.  The
   enterprise costs for privately owned landfills, therefore,.are
   annualized over the period from 1993 until the landfill
   closes,  using an 8  percent interest rate.
        3.3.1.3  Cost  per Ma of MSW.  To compute the annualized
   enterprise cost per Mg of MSW for affected existing landfills,
   the annualized cost was divided by the quantity of waste
   accepted by the landfill in 1986.*  One measure of the average
   annualized cost per Mg of waste accepted is the national
   annualized cost per Mg of MSW, which is computed for each
   stringency level by summing the annualized enterprise costs
   for all the affected landfills at that level, and then
   dividing by the summed quantities of waste accepted by all the
   affected landfills  in 1986.  The national annualized costs per
   Mg  of MSW presented in Table 3-10 range from $1.22 per Mg at
   the 100 Mg stringency level to $1.27 per Mg at the 50 Mg
   level.  Although these numbers are greater than those reported
   in  the proposed rule option, they are not radically different
   and do not vary significantly across stringency levels.
   '  Aa noted in Section 3.3, the historical annual average amount of MSW
     accepted by the landfill is substituted for the quantity of MSW received
     in 1986 for some landfills.

kli-85\0*                           3-21

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                                  3-22

-------
        Table  3-10  also  contains  a  frequency  distribution  of
   affected landfills  by annualized cost per  Mg  of MSW accepted
   in 1986.  At  the 50 Mg stringency level, about 40  percent  of
   landfills experience  annualized  costs of $1.25 per Ng or less.
   The maximum annualized cost  at this  level  of  stringency,
   however,  is $8 per  Mg.   At the 75 Mg stringency level the
   maximum annualized  cost falls  to $7  per Mg of MSW,  and  the
   proportion  of landfills that experience costs of $1.25  per Mg
   or less increases to  45 percent.   Finally,  at the  100 Mg
   stringency  level, 44  percent of  affected landfills experience
   annualized  costs per  Mg of MSW of $1.25 or less, and the
   maximum annualized  cost experience is only $6 per  Mg.
        Privately Owned  Closed/Existing Landfills.  The
   enterprise  costs for  privately owned landfills were annualized
   over a  period beginning in 1992  and  ending when the landfill
   closes.   Privately  owned landfills can only recapture their
   costs through increased user fees while they  are still
   accepting MSW.   The shorter  the  period of  time between  1992
   and the year  the landfill closes,  therefore,  the greater the
   potential burden of a particular amount of control costs on
   the landfill's owners.   Tables 3-11  and 3-12  give  the same
   information as Table  3-10, but for privately  owned landfills
   that have 5 or fewer  years until closure to 10 years until
   closure,  respectively.   Table  3-11 shows that the  national
   annualized  enterprise cost per Mg of MSW accepted  for private
   landfills with 5 years or less until closure  is more than
   three times the  national annualized  costs  for all  affected
   landfills at  each stringency level.  Specifically,  at the  100
   Mg stringency level,  the national annualized  enterprise cost
   is at the 100 Mg stringency  level, the national annualized
   enterprise  cost  is  $5.42 per Mg  of MSW; it is $4.20 per Mg of
   MSW at  the  75 Mg level,  and  it is $4.79 per Mg at  the 50 Mg
   stringency  level.  At the 75 Mg  stringency level,  83 percent
   of the  12 affected  landfills that are expected to  close before
   1998 experience  annualized costs between $3.00 and $10.00  per
   Mg of MSW.

klk-85\04                          3-23

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       For private landfills closing between 1998 and 2002, unit
  control costs are not nearly as high as the unit control costs
  of private landfills closing before 1998 (see Table 3-12).
  The national average measure is $1.79 per Mg of MSW at the 50
  Mg stringency level, $1.75 per Mg of MSW at the 75 Mg
  stringency level, and only $1.62 per Mg at the 100 Mg
  stringency level.  At the 100 Mg stringency level, only four
  landfills affected are expected to close between 5 and 10
  years after 1993, and these landfills incur costs less than
  $1.62 per Mg of MSW.  At the 75 Mg stringency level, only four
  affected landfills are expected to close between 1998 and
  2002, and these landfills experience annualized enterprise
  costs between $1.25 per Mg and 3.00 per Mg.  At the 50 Mg
  level, four landfills are expected to close between 1998 and
  2002, with annualized costs between $1.25 per Mg and $3.00 per
  Mg.
       New Landfills.  The national annualized enterprise cost
  per Mg of MSW for new landfills, presented in Table 3-13, is
  $0.62 at the 50 level.  At the 75 level, the enterprise
  control cost per Mg is $0.58, and the cost per Mg at the 100
  level is $0.59.  Table 3-13 also provides a frequency
  distribution of affected new landfills by the annualized
  enterprise cost per Mg of MSW accepted.  This distribution
  reveals that the higher the stringency level, the higher the
  proportion of affected landfills incurring annualized costs
  greater than $1.00 per Mg of MSW accepted.  At the least
  stringent 100 Mg cutoff level, only 23 percent of the 33
  affected landfills have costs of $1.00 per Mg or higher, and
  no affected landfill experiences annualized costs exceeding
  $1.39 per Mg.  At the 75 Mg stringency level, however, over 40
  percent of the 56 affected landfills have annualized costs
  over $1.00 per Mg; at this stringency level, the maximum
  annualized cost  is $1.41 per Mg of MSW.  Finally, at the most
  stringent 50 Mg  level, 36 percent of the 89 affected landfills
  have annualized  costs of $1.00 per Mg or higher, and the
  maximum annualized cost is $1.44 per Mg.

ktt-85\o*                           3-26

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                                            3-27

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       3.3.1.4  Cost per Household.  This calculation attempts
  to assess the annualized cost that will be borne by households
  served by affected landfills.  To compute this measure, the
  annualized enterprise costs are divided by an estimated number
  of households served by the affected landfills.  The national
  annualized enterprise cost per household for each stringency
  level is computed by summing the annualized enterprise costs
  incurred by all affected landfills at that stringency level,
  and then dividing by an estimate of the total number of
  households served by those landfills in 1986.
       BKJftifr? Landfills.  Table 3-14 presents the annualized
  enterprise cost per household for affected existing landfills.
  The national annualized enterprise cost ranges from $4.84 per
  household at the 100 Mg stringency level to $5.02 per
  household at the 50 Mg stringency level.  At the intermediate
  75 Mg stringency level, the national annualized enterprise
  cost is $4.95 per household.
       The frequency distribution of affected landfills by
  annualized enterprise cost per household, also shown in Table
  3-14, indicates that 23 percent of affected landfills at the
  50 Mg stringency level will incur annualized enterprise costs
  of $3.50 per household or less. At the 75 Mg stringency level,
  24 percent of the affected landfills will incur annualized
  costs of $3.50 or less per household.  At the  100 Mg
  stringency level, 22 percent of the affected landfills
  experience annualized costs of $3.50 or less per household.
       Mew Landfills.  Table 3-15 assesses the potential impact
  of the regulatory alternatives on the households that will  be
  served by new landfills based on the annualized enterprise
  cost per household.  The national cost per household varies
  from $2.32 at the 100 Mg stringency level to $2.30 at the 75
  Mg stringency level to  $2.45 at  the 50 Mg stringency level.
       3.3.1.5  Recordkeepina  Costs.  All regulations impose
  administrative and recordkeeping costs on affected facilities.
  All facilities,  including those  below the size cutoff, must
  file reports concerning the  amount of waste  they accept.  We

kii-85\o*                           3-28

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   assumed  the minimal  reports done by  facilities below the  size
   cutoff does not  contribute significantly to the  total
   recordkeeping costs,  so  their  costs  are not included here.
        For facilities  that must  install  controls,  recordkeeping
   costs include tracking quantities of waste received,
   installing monitoring devices  and tracking emissions levels,
   and  issuing the  appropriate reports  to the regulating  agency.
   This regulation  would require  many landfills  to  incur  costs of
   keeping  track of the quantities of waste landfilled and the
   quantities of emissions  generated whether they eventually
   needed to install controls or  not.
        EPA has  established a progressive Tier System for
   determining whether  a particular facility is  covered by the
   regulation under review.5  In essence, any facilities not
   exempted by the  size cutoff have to  ascertain by a series of
   tests whether they must  install controls.  If testing
   indicates a facility must install controls at Tier 1,
   additional reporting, testing, and recordkeeping requirements
   occur at Tier 2.   If the facility must still  control emissions
   at Tier  2, additional requirements occur at Tier 3, and so on.
   At each  level, a facility may  be exempted from controls and
   further  testing;  however, it has already incurred the
   recordkeeping costs  at that level  (see Table  3-16).
        EPA also incurs recordkeeping costs in tracking and
   monitoring facilities.   Table  3-16 presents these record-
   keeping  costs as the agency cost.  In  the second half  of  this
   table, the total cost per landfill excludes agency costs.
        The table presents  the recordkeeping costs  for the 100
   Mg/year  stringency level only.  The  number of facilities  that
   must install  controls is estimated to  be 477  rather than  305
   as stated in  Table 3-1.   The main reason for  the difference  is
   that some landfills  have already installed controls for a
   variety  of reasons.   These landfills would incur no capital  or
   operating compliance costs as  a result of the regulation, and,
   therefore, would have only additional  recordkeeping costs. We
   also assumed  in  Table 3-16 that all  controlled facilities

klk-85\04                           3-31

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  would  incur all of the recordkeeping costs whereas, in
  reality, that may not be necessary,  some facilities,
  correctly assuming that they must install controls, may skip
  directly to Tier 3.
       Recordkeeping costs are expected to be only about
  3.5 percent of the total enterprise costs per landfill.
  Therefore, they have been addressed separately and are not
  included in the estimated impacts presented in other sections
  of this report.
  3.3.2  Social Costs
       Social costs are those costs borne by society as a whole.
  They include investment and consumption foregone in the
  private sector by virtue of using private sector resources  for
  public purposes.  This analysis presents an estimate of social
  costs  of the final rule for landfills.  Note that these
  estimates do not reflect the benefits to society resulting
  from a change in air quality.  We used social costs in our
  estimates of cost effectiveness.
       3.3.2.1  NPV of Social Costs.  A measure of the potential
  cost to society of complying with the regulatory alternatives
  is the NPV of social costs.  This measure is computed by  first
  annualizing capital costs and  then discounting the flow of
  capital and operating costs.   The resulting figure is a
  measure of the present value of the costs that will be
  incurred throughout the control periods for the various
  landfills.  A net present value measure of costs is the
  appropriate way to compare costs between landfills because
  most landfills will begin and  end controls at different times.
  The NPV of social costs presented below are computed using  a 7
  percent discount rate.
       Closed/Existing Landfills.  When summed across all
  affected landfills under each  stringency level, the national
  total  NPV of social costs ranges from $1.085 billion under  the
  100 Mg stringency level to $1.662 billion under the 50 Mg
  stringency level  (see Table 3-17).  Although more landfills
  are affected under the more stringent 50 Mg level than under

klk-85\0*                           3-33

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                                            3-34

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   the other  two  stringency  levels, a  larger proportion of
   affected landfills  incurs relatively  lower NPV  of  social  costs
   ($3 million  or less)  under the  50 Mg  level than under the
   75  Mg  level or the 100 Mg level.   The mean NPV of social
   costs per  affected  landfill under the 100 Mg  stringency,  $3.56
   million, exceeds the mean NPV of social  costs for  the other
   two stringency levels.                           '*
        Mew Landfills.   Table 3-18 presents the  NPV of social
   costs for  affected  new landfills.   Total social costs increase
   as  the level of stringency increases.  At the most stringent
   50  Mg cutoff level,  the aggregate total  NPV of  social costs,
   $1.34 billion,  is about twice the aggregate total  NPV of
   social costs at the 100 Mg level, $72 million.  The aggregate
   total NPV  of social costs at the 75 Mg level, $95  million,
   lies between the cost of  the other  stringency levels.  The
   number of  affected  landfills increases substantially as the
   stringency level increases, and the average NPV of social
   costs per  landfill  decreases as the level of  stringency
   increases.   The frequency distribution in Table 3-18 shows
   that 96 percent of  new landfills have an NPV  of 3  million or
   less at the  50 Mg/yr level, while 93  percent  have  social  costs
   of  this size at the 75 level and 88 percent at  the 100 level.
        3.3.2.2  Annual!zed  Social Costs.
        Closed/Existing Landfills.  Annualizing  the NPV of social
   costs provides another measure  of the cost to society of  the
   regulatory alternatives under consideration.  We annualized
   the NPV of the social cost of each  affected landfill over the
   years from 1992 to  the end of the landfill's  control period
   using a 7  percent discount rate; then we summed these
   individual annualized values to get the  total annualized
   social cost.   The resulting total annualized  social cost  for
   affected closed and existing landfills for each stringency
   level is the following:
       • $128 million for the 50 Mg stringency level,
       • $103 million for the 75 Mg stringency level, and
       • $83 million for the 100 Mg stringency level.

klk-85\04                          3-35

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        Thus,  the  annualized  social cost of the 75 Mg  stringency
   level is  24 percent higher than the annualized social cost  of
   the  100 Mg  stringency  level.  The annualized social cost  of
   the  50 Mg stringency level is 24 percent higher than the
   annualized  social  cost  for the 75 Mg stringency  level.
        Mew  Landfills.  The total annualized social  cost for
   affected  new  landfills for each stringency  level  fs the
   following:
       • $10.mi11ion for the 50 Mg stringency level,
       • $7 million for the 75 Mg stringency level,  and
       • $5 million for the 100 Mg stringency level.
        As expected,  the  least stringent regulatory  alternative
   (the 100  Mg stringency level) has the lowest annualized social
   cost,  and the most stringent regulatory alternative (the  50 Mg
   stringency  level)  has  the  highest annualized social cost.
   3.3.3 Emissions Reduction and Cost Effectiveness
        Although we are considering the costs  of complying with
   the  §111(d) and lll(b) final rule options,  we must  also
   consider  the  cost  effectiveness of these alternatives.  Cost
   effectiveness is measured  as the annualized compliance cost
   per  Mg of reduction in the emission of NMOCs.  We express
   cost-effectiveness ratios  as national figures.  The sum of  all
   compliance  costs for all affected landfills is divided by the
   sum  of emissions reductions for all affected landfills.   In
   addition, we  calculated  the incremental cost effectiveness  or
   the  change  in cost effectiveness as the stringency  level
   increases.
        3.3.3.1  gmi!ssjons  Reduction of Closed/Existing
   Landfills.  Table  3-19 shows the emissions  reductions
   resulting from  the three regulatory alternatives  under the
   flare option.   Total undiscounted NMOC emissions  reductions
   range from  4.4  million Mg  at the 100 Mg stringency  level, to
   4.8  million Mg  at  the  75  Mg stringency level, to 5.3 million
   Mg at the 50  Mg stringency level.  The emissions  reductions
   are  spread  over the period of time during which the affected
   landfills are using the  flare emission controls.  In order  to

kli-85\0*                           3-37

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                                        3-38

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   compare  emissions  reductions with the costs from
   Section  3.3.2.1, we  discounted the NMOC emissions reductions
   using a  7  percent  rate  of discount.  The discounted NMOC
   emissions  reductions range  from  1.2 million Mg at the  100 Mg
   stringency level to  1.3 million  Mg at the 75 Mg stringency
   level to 1.4 million Mg at  the 50 Mg stringency level.  The
   average  discounted NMOC emission reduction decreases as the
   stringency level increases, because the number of affected
   landfills  increases  faster  than  the NMOC emissions reductions.
   Thus,  the*average  NMOC  emission  reduction per affected
   landfill is 3,873  Mg at the 100  stringency level, 3,071 Mg at
   the  75 Mg  stringency level, and  2,381 Mg at the 50 Mg
   stringency level.
        Cost  Effectiveness of  Closed/Existing Landfills.  He
   combined measures  of NMOC emissions reductions with the
   discounted NPV of  social costs presented in Table 3-17 to
   estimate the cost  effectiveness  of the flare option for
   closed/existing landfills.  At the top of Table 3-20 is the
   national cost  effectiveness of each stringency level,  computed
   by dividing the aggregate NPV of total social cost by  the
   total discounted NMOC emissions  reduction.  The national cost
   effectiveness  of the flare  option at the 100 Mg stringency
   level is $918  per  Mg of NMOC reduced.  At the 75 Mg stringency
   level, the national  cost effectiveness is $1,051 per Mg of
   NMOC reduced,  and  the national cost effectiveness is $1,220
   per  Mg of  NMOC reduced  at the most stringent 50 Mg level.
        The frequency distribution  of affected landfills  by cost
   effectiveness  (Table 3-20)  demonstrates that as the stringency
   level decreases, an  increasing proportion of landfills has a
   cost effectiveness under $1,000  per Mg of NMOC reduced.  At
   the  50 Mg  stringency level, only 17 percent of affected
   landfills  have cost-effectiveness measures that low, while 23
   percent  of affected  landfills fall below $1,000 per Mg of NMOC
   at the 75  Mg stringency level.   Finally, 32 percent of the
   affected landfills have a cost effectiveness less than $1,000
   per  Mg of  NMOC at  the 100 Mg stringency level.  At the bottom

klk-85\04                           3-39

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   of  the table,  incremental  cost effectiveness measures the
   change in  national  cost  effectiveness experienced as the
   stringency level  increases first  from 100 Mg to  75 Ng and then
   from 75 Mg to  50  Mg.  As the  stringency  level  increases from
   100 Mg to  75 Mg,  the  incremental  cost effectiveness is $2,755
   per Mg of  NMOC reduced.  Moving from 75  Mg to  50 Mg results in
   an  incremental cost effectiveness of $3,655 per  Mg of NMOC
   reduced.
        B»jfff j.on  Reduction  of Mev Landfills.  Table 3—21 shows
   the emissions  reductions for  new  landfills under the flare
   control option.   The  first line shows the total  undiscounted
   NMOC emissions reductions  at  each stringency level.  These
   measures,  showing the total emissions reductions achieved
   throughout the control period for all affected new landfills,
   range from 0.42 million  Mg at the 100 Mg stringency level, to
   0.49 million Mg at  the 75  Mg  stringency  level, to 0.58 million
   Mg  at the  50 Mg stringency level.
        The discounted NMOC emission reduction, when summed
   across all affected landfills, ranges from 0.73  million Mg at
   the 100 Mg stringency level to 0.82 million Mg at the 75 Mg
   stringency level  to 0.94 million  Mg at the 50  Mg stringency
   level.
        The average  discounted NMOC  emission reduction per
   affected landfill is  much  higher  at the  100 Mg stringency
   level than at  the 50  Mg  stringency level because the number of
   affected landfills  falls faster than discounted  NMOC reduction
   as  the stringency level  decreases.  At the 100 Mg stringency
   level, the average  discounted NMOC emission reduction is 2,196
   Mg  of NMOC, more  than two  times the average discounted NMOC
   emission reduction  per landfill at the 50 Mg stringency level
   (1,060 Mg  of NMOC).   At  the 75 Mg stringency level, the
   average discounted  NMOC  emission  reduction, 1,455 Mg of NMOC
   per affected landfill, falls  between  the average emission
   reduction  values  of the  other two stringency levels.  The
   frequency  distribution of  affected new landfills by discounted
   NMOC emission  reduction  shows that the proportion of landfills

kli-85\OA                          3-41

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                                          3-42

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   achieving relatively greater  NMOC  emissions  reduction
   increases as  the stringency level  decreases.
        Cost Effectiveness  of  New Landfills.  We  can  construct
   cost-effectiveness measures for affected new landfills toy
   combining information about emission  reductions  (presorted i
   Table 3-21) for new landfills with information about  the NPV
   of  social costs (Table 3-18).   As  presented  in Table  3-22  this
   value ranges  from $997 per  Mg of NMOC reduced  at the  100 Mg
   stringency level,  to $1,160 per Mg of NMOC at  the  75  Me level,
   to  $1,427" per Mg of NMOC at the 50 Mg stringency level.  The
   frequency distribution demonstrates that, as with  close:'/
   existing landfills, the  proportion of affected new land.f ills
   having cost-effectiveness measures less than $2,000 per Mg of
   NMOC increases as the degree  of stringency decreases.  At  the
   50  Mg stringency level,  only  28 percent of landfillr  have  a
   cost effectiveness under $2,000 per Mg of NMOC,  while at the
   75  Mg stringency level,  38  percent have a cost effectiveness
   of  $2,000 per Mg or less.  At the  100 Mg stringency level,
   65  percent of affected landfills have a cost effectiveness
   under $2,000  per Mg.
        The last line of Table 3-22 shows incremental cost
   effectiveness for new landfills (i.e., the change  in  cost
   effectiveness experienced as  one moves from  the  100 Mg
   stringency level to the  75  Mg level,  and then  from the 75  Mg
   stringency level to the  50  Mg stringency level).  As  the
   stringency level decreases  from 100 Mg to 75 Mg, the
   incremental cost effectiveness is  2,460 per  Mg of  NMOC
   reduced.   The incremental cost effectiveness of  moving from
   the 75 Mg stringency level  to the  50  Mg stringency level  is
   3,184 per Mg  of NMOC reduced.

   Flexibility Analysis of  1980  requires Federal  agencies to
   determine if  regulations will have a  "significant  economic
   impact on a substantial  number of  small entities." EPA
   guidelines on determining whether  a regulatory flexibility
   analysis is required defines  a "substantial  number1* as 20

klk-85\04                          3-43

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                                          3-44

-------
   percent  of  all  affected  entities.  Neither the proposed  rule
   options  nor the final rule options will affect a  substantial
   number of small entities under these guidelines.
   Nevertheless, an analysis of  the  impacts on households and
   government  jurisdictions was  performed for the proposed  rule
   options.  The cost  per household  and the cost per Mg  computed
   for  the  final rule  options are not significantly  different
   from those  presented for the  proposed rule.  Consequently,  a
   revised  distributional analysis is not warranted.
   3.4   COSTS  OF REGULATIONS AFFECTING LANDFILLS
        Landfills  and  their close substitutes municipal  waste
   combustors  (MWCs) are both subject to regulations that are  in
   the  final stages of development.  In particular,  the  municipal
   waste combustor regulation, which will regulate the
   incineration of municipal solid wastes  (MSW), increases  the
   costs of providing  MWC services.  The air pollution regulation
   for  landfills,  analyzed  in this report, is similarly  expected
   to increase the costs of providing landfill services.
        Because the regulations  are  still under development, we
   do not know their final  form  or the exact costs that  will be
   associated  with them.  However, we expect the MWC regulatory
   costs to be higher  than  the landfill air emission costs.
   Therefore,  we expect the share of waste going to  MWCs to
   decline  and the share of waste going to landfills to  rise.
        Based  on the expected relative magnitudes of the
   compliance  costs of the  two regulations, the expected market
   adjustments resulting from the interaction of these
   regulations are illustrated in Figures 3-2 and 3-3.   In  each
   figure,  DI and  S2 show the demand  and supply  for the waste
   disposal service in the  absence of the regulation.  D2 and  S2
   show the demand and supply with the regulations in effect.
        Demand and supply for MWC services is presented  in
   Figure 3-2.  The supply  curve, Si, is expected to shift
   upwards  substantially to S2 due to increased MWC regulatory
   costs.
klk-85\0*                           3-45

-------
    $/Mg
      (P)
                         Q2 Q, Qa
Mg of MSW
      (Q)
Figure 3-2.   Expected impacts of  coata of regulations  on
               municipal  waate combustors.
    $/Mg
      (P)
                       Q2 Q3
Mg of MSW
      (Q)
        Figure 3-3.  Expected impacts of costs of regulations
                        on sanitary landfills.
W2TO:BID (05/25/95)
                                 3-46

-------
 Th..s shift results in an increase in price (P2) and a decrease
 in quantity cf MWC services (Q2) .  Sanitary landfills  (Figure
 3-3)  also are expected to experience a decrease in supply due
 to the costs of air emission controls (S3  to Sj),  but this
 shift is expected to be smaller than that experienc^c  by MKCs
 because the compliance costs are thought to be lower.   The
 shift results in an increase in price (P2) and a corresponding
 decrease in quantity of landfill services demanded (Q2).
      Demand for a good or service depends, among other things,
 on the prices for substitutes.   KWC  and sanitary landfill
 services are considered to be close  substitutes.   Generators
 of KSW n,ay choose to either landfill their solid waste or to
 incinerate it.  However, because of  transportation costs,
 legal restrictions on shipments of solid wastes,  and the
 geographical distribution of MWC and sanitary  landfill
 facilities, they are not perfect substitutes.    Because they
 are close substitutes, the increased prices desc_ioed above
 rer it in changes in demand for the  substitute services.  The
 increased price of landfill services is expected to increase
 the demand for MWC services and vice versa.  The increased
 demand for MWC services (D2 in  Figure  3-2) results in another
 increase in price and a small relative increase in quantity
 (P3 and  Q3).   The increased price of KWC services  ;suits in
 increased demand for landfill services.   This  increased demand
 will result in both higher prices and higher  quantities for
 landfill services (Q3  and  P3 in Figure 3-3).
      Overall, both the MWC regulations and the landfill
 regulations increase the cost of disposing of  MSW.   The
 overall quantity of waste disposal is expected to decline,
 other things being equal.   Because the compliance costs
 associated with the MWC regulation are expected to be larger
 than the compliance costs associated with the  landfill
 regulations, the relative share of waste sent  to MWCs is
 expected to fall and the relative share of waste landfilled is
 expected to increase.   In the illustrations presented here,
 the absolute quantity of landfill services with both
-B5\04                          3-47

-------
  regulations in effect is greater than it was at baseline.
  Whether the absolute quantity will in fact be greater or less
  is an empirical issue, but the share of waste being sent to
  landfills should increase.
  3.5  SUMMARY AND CONCLUSIONS
       We focused our economic analysis on the flare option for
                                                   • \
  controlling NMOC emissions from closed/existing and new
  landfills.  The flare option assumes that all affected
  landfills will control NMOC emissions using flares, which
            *
  overestimates the actual cost of the regulatory alternatives
  because some landfills will choose a cheaper energy recovery
  option.
       As discussed in Section 3.1, two features of the
  engineering costing model are noteworthy for the economic
  analysis.  First, the model assumes that landfills that close
  between 1987 and 1997 are replaced by an identical landfill
  serving the same area, even though recent evidence indicates
  that the number of U.S. landfills is actually declining.  The
  model also uses relatively high MSW acceptance rates, which
  are important parameters in determining NMOC emissions rates
  and the cost of emissions controls.  These features lead to
  overestimates of the number of affected landfills, compliance
  costs, and emissions reductions.
       In summary, the actual economic impacts of the Slll(d)
  and lll(b) regulatory alternatives under consideration are
  probably  less than the economic impacts presented  in this
  chapter.  Nevertheless, our analysis of these regulatory
  alternatives leads to several specific conclusions:
       •  The regulatory alternatives will affect only a small
         fraction of the closed/existing and new landfills
         (generally less than 10 percent),  and most of the
         affected landfills are small (less than 5 million Mg
         capacity).
       •  The number of affected closed private landfills, which
         have no way of generating revenues to cover compliance
         costs,  is small under the flare option.
kli-85\0*                           3-48

-------
    • The national NPV of enterprise costs decreases
      substantially as the stringency level decreases under
      both control options for affected closed/existing and
      new landfills, but the average enterprise cost rises as
      the stringency level decreases.

    • The national arnualized enterprise cort.ro! cost per Mg
      of MSW  is below $1.30 p?r Kg for all stringency levels
      under the flare option tcr affected existing and new
      landfills.

    • The costs of the regulatory alternatives are very low
      for most households — the majority of affected existing
      landfills : i\'s compliance costs wide- $€.00 per
      household per year and the majority c-  affected new
      landfills have compliance costs under $2.50 per
      household per year .

    • Although the national cost effectiveness of all the
      stringency  levels under the flare option is less than
      $1,500  per  Mg of NMOC emissions reduction, cost
      effectiveness varies greatly among affected landfills-
      much more than is typical for EPA
    •  The  regulatory  alternatives under consideration  for
       closed/existing and new  landfills will not  affect  s
       substantial  number of  small entities, so  a  Regulatory
       Flexibility  Analysis is  not required  for  either  the
       §111 (d)  or lll(b) rulemakings.  Nevertheless,  the
       analysis of  the proposed rule options included a
       distributional  analysis  of the  impacts on affected
       households and  government entities.   The  cost  per
       household and the cost per Mg computed for  the final
       rule options are not significantly different from  those
       presented for the proposed rule.  Consequently,  a
       revised  distributional analysis is not warranted.

    •  The  social costs of the  regulatory alternatives  for
       affected closed/existing and new landfills  are very
       sensitive to the discount rate  because of the  long
       control  periods under  stringency levels for both the
       flare and energy recovery control options.

     In general, the economic impacts of the §111 (d)  and

lll(b)  regulatory alternatives on households and

municipalities are too small to significantly influence the

choice among these alternatives.   Privately owned landfills

that are already closed and must install emissions controls

may be significantly affected by the regulatory alternatives

because they have no way of recovering their compliance costs.


                             3-49

-------
  However, very few closed, privately owned landfills are
  affected under any of the regulatory alternatives.  The
  control costs of the regulatory alternatives at affected
  landfills will probably not lead to a significant shift in NSW
  flows from landfills to municipal waste combustors.  Finally,
  all of the regulatory alternatives will stimulate the adoption
                                                   • \
  of energy recovery technologies at affected landfills.
       Table 3-23 compares the estimated impacts computed for
  the proposed rule and those computed for the final rule.  Note
  that the emission cutoff levels evaluated under the.proposed
  rule option (25, 100, and 250 Ng NMOC) differ from those under
  the final rule option (50, 75, and 100 Hg NMOC).  Since the
  100 Mg stringency level is the only one analyzed for both the
  proposed and final rule options, it is the level presented and
  compared in Table 3-23.  Consequently, comparisons of the
  impacts under the proposed and final options should be made
  with the understanding that the stringency levels evaluated
  are different under the two analyses.  Four of the measures
  presented in Table 3-23 are particularly relevant for
  comparison of impacts under the two analyses:  number of
  affected landfills, total compliance cost, total emission
  reduction, and cost effectiveness.
       The estimated number of potentially affected landfills  is
  lower under the final rule than the proposed rule.  This
  difference results from the revised waste flow estimates and
  revised engineering assumptions used to compute  impacts for
  final rule (see discussion in Section 3.1).  Furthermore, the
  size cutoff for landfills with an acceptance rate below l
  million Mg of MSW per year excludes some landfills from the
  analysis of impacts under the final options that were affected
  under the proposed rule.  The difference in the  number of
  affected landfills results in differences in the estimated
  compliance costs and the estimated emission reductions as
  described below.
       This analysis presents two measures of total compliance
  costs:  NPV of social costs and NPV of enterprise costs.
kli-8S\0*                           3-50

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  TABLE  3-23.  SUKJ4ARY OF DX??E&EN€£S B1TWEBH THE PROPOSED RULB
               AND FINAL RULE  OPTIONS AT THB 100 MO PER  YEAR
               STRINQSMCY LEVEL
Category
Number of Affected Landfills:
closed/existing
new
Average Control Period
(years) :
closed/existing
new
Total NPV of Average
Enterprise Costs for Affected
Landfills ($/landf ill) :
closed/existing
new
Annualized Control Cost per
Household ($ per household) :
closed/ exist ing
new
National Emissions Reductions
(Mg NMOC per year) :
closed/ exist ing
new
National Cost Effectiveness
($/Mg NMOC) :
closed/ exist ing
new
National NPV of Total
Enterprise Cost ($) :
closed/ exist ing
new
National NPV of Total Social
Costs ($) :
closed/ exist ing
new
Proposed Rultt
option
853
104
66.3
59.6
$4,260,000
$3,920,000
$4.90
$2.78
28,600,000
2,330,000
$640
$1,081
$3,634,000,000
$407,000,000
$7,157,000,000
$896,000,000
Final Rul*
Option
305
33
51,8
38.6
$4,490,000
S3.44C.OOO
$4.84
$2.32
4,396,000
419,000
$918
$997
$1,370,000,000
$114,000,000
$1,085,000,000
$72 , 000, 000
kLk-85\04
                                 3-51

-------
  Under both cost measures the impacts estimated for the final
  rule are lower than those estimated for the proposed rule.
  Enterprise costs are lower because fewer landfills are
  affected under the final rule.
       Social costs are lower for two reasons.  As is true for
  the estimate of enterprise costs, social costs are lower
                                                   •«
  because fewer landfills are affected under the final rule.
  Second, the NPV of social costs under the final rule is
  computed based on a 7 percent discount rate while the
  corresponding measure for the proposed rule was computed using
  a 3 percent discount rate.  Using a higher discount rate
  results in an NPV of social costs that is substantially lower,
  even on a per-landfill basis.  We used a different discount
  rate for our analysis of social costs under the final rule to
  reflect recently revised OMB guidance on the appropriate
  social discount rate.
       Emission reductions are lower under the final rule than
  under the proposed rule.  The difference in undiscounted
  emission reductions is attributable to the difference in the
  number of affected landfills.  Discounted emission reductions
  are lower under the final rule because fewer landfills are
  affected and the discount rate used is higher.
       Finally, cost effectiveness is computed as the NPV of
  social costs divided by the discounted emission reduction.
  Because both costs and emission reductions are proportionately
  lower under the final options, cost effectiveness is not
  significantly different.
klk-85\0*                           3-52

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   3.6   REFERENCES


   1.    U.S.  Environmental  Protection Agency.   Background
        Document for the Solid waste Dilemma:   An Agenda for
        Action.   Draft Report of  the Municipal Solid, Waste Task
        Force, Office of Solid Waste,  U.S.  Environmental
        Protection Agency.   September 1988.

   2.    U.S.  Environmental  Protection Agency.   National Survey of
        Solid Waste (Municipal) Landfill  Facilities.  Prepared by
        Westat,  Inc.   EPA 68-01-7359,  September 1988.  p. 7-3.

   3.    Federal  Register.   Standards of Performance Proposed
        Rule.  56:104.   May 30, 1991.

   4.    Morris,  G. E.,  B.  L.  Jeliicorse,  K.  B. Heller,  T. P.
        Neely, and T.H.  Bingham.   Economic  Impact of Air
        Pollutant Emission  Standards for  New Municipal kaste
        Combustors.   Research Triangle Institute.  Final report
        prepared for Office of Air Quality  Planning and
        Standards, U.S.  Envircnacntal Protection Agency, Research
        Triangle Park,  NC.   August 198S.  p. 3-1.

   5.    Reference 3.

   6.    Memorandum,  from Pelt, R., Radian Corporation,  to Curtis-
        Powell,  S.,  Research Triangle Institute.  July 15, 1593.
        Recordkeeping costs.
klk-85\0*                           3-53

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                              TECHNICAL REPORT DATA
                              •'ts'.'.'ZV'^ns on tn« reverse &**ore completing)
    'l No.
  EPJ-.-4S3/R-94-021
                                                   3. RECIPIENTS ACCESSION SO.
4. TTOE AND SUBTTTIE
  Air  Emissions  from Municipal Solid Waste
  Landfills^-Background Information for
  Final Standards and Guidelines
              5. REPORT DATA
                December 1995
              6. PERFORMING ORCtf-N 2ATON CODE
7. AUTHOR(S)
                                                   6. PERFORMING ORGANIZATION
                                                                       NO.
3. PERFORMING l^GANIZATION NAME AND ADC3"SS
  Office  of Air  Quality Planning and
    Standards
  U.S.  Environmental Protection Agency
  Research Trrangle P&rk,  N.C.  27711
                                                   10. PROGRAM ELEMENT NO.
              11. CONTRACT/GRAN! NO

                68-D1-C1.17
12. SPONSOWNQ AGENCY NAME AND ADDRESS
  Director, Office of Air  Quality Planning
    and Standards
  Office of Air  and Radiation
  U.S.  Environmental Protection Agency
  Research Triangle Fsrk,  N.C.  27711
                                                   13. TYPE OF REPORT AND PSKOD COVERET
              14. SPONSORING AGE:
-------