Effluent Limitations Guidelines, Pretreatment Standards, and New Source Performance Standards for the Landfills Point Source Category
Federal RegisterFeb 6, 1998
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SUMMARY: This proposal represents the Agency's first effort to develop
Clean Water Act (CWA) national effluent limitations guidelines and
pretreatment standards for wastewater discharges from stand-alone
landfills unassociated with other industrial or commercial activities.
The proposed regulation would establish technology-based effluent
limitations for wastewater discharges to navigable waters associated
with the operation of new and existing hazardous and non-hazardous
landfill facilities regulated under Subtitle C or Subtitle D of the
Resource Conservation and Recovery Act (RCRA). The proposal would also
establish pretreatment standards for the introduction of pollutants
into Publicly Owned Treatment Works (POTW) associated with the
operation of new and existing hazardous landfills regulated under
Subtitle C of RCRA. Sources of landfill wastewater at these facilities
include, but are not limited to, landfill leachate and gas collection
condensate.
The proposal would not establish pretreatment standards for the
introduction of pollutants into Publicly Owned Treatment Works (POTW)
associated with the operation of new and existing non-hazardous
landfills regulated under Subtitle D of RCRA.
The proposal would not apply to wastewater discharges from captive
landfills located at industrial facilities that commingle landfill
process wastewater with non-landfill process wastewater for treatment,
provided that the landfill receives only waste generated on-site or
waste generated from a similar activity at another facility under the
same corporate structure. Further, the proposed regulation would also
not apply to wastewater discharges associated with treatment of
contaminated groundwater from hazardous and non-hazardous landfills.
Compliance with this proposed regulation is estimated to reduce the
discharge of pollutants by at least 800,000 pounds per year and to cost
an estimated $ 7.71 million annualized (1996 dollars, post-tax for non-
government facilities).
DATES: Comments on the proposal must be received by May 7, 1998.
In addition, EPA will conduct a workshop and public hearing on the
pretreatment standards of the rule. The meeting will be held on
February 24, 1998, from 10:00 am to 2:00 pm.
ADDRESSES: Send written comments and supporting data on this proposal
to: Michael Ebner, US EPA, (4303), 401 M Street S.W., Washington, D.C.
20460. Please submit an original and two copies of your comments and
enclosures (including references).
To ensure that EPA can read, understand and therefore properly
respond to comments, the Agency would prefer that commenters cite,
where possible the paragraph(s) or sections in the notice or supporting
documents to which each comment refers. Commenters should use a
separate paragraph for each issue discussed.
Commenters who want EPA to acknowledge receipt of their comments
should enclose a self-addressed, stamped envelope. No facsimiles
(faxes) will be accepted. Comments and data will also be accepted on
disks in WordPerfect format or ASCII file format.
Comments may also be filed electronically to
``Ebner.M[email protected]''. Electronic comments must be
submitted as an ASCII or Wordperfect file avoiding the use of special
characters and any form of encryption. Electronic comments must be
identified by the docket number W-97-17 and may be filed online at many
Federal Depository Libraries. No confidential business information
(CBI) should be sent via e-mail.
The public record is available for review in the EPA Water Docket,
401 M Street S.W., Washington, D.C. 20460. The record for this
rulemaking has been established under docket number W-97-17, and
includes supporting documentation, but does not include any information
claimed as Confidential Business Information (CBI). The record is
available for inspection from 9 a.m. to 4 p.m., Monday through Friday,
excluding legal holidays. For access to docket materials, please call
(202) 260-3027 to schedule an appointment.
The workshop and public hearing covering the rulemaking will be
held at the EPA headquarters auditorium, Waterfront Mall, 401 M St. SW,
Washington, DC. Persons wishing to present formal comments at the
public hearing should have a written copy for submittal.
FOR FURTHER INFORMATION CONTACT: For additional technical information
contact Mr. Michael Ebner at (202) 260-5397. For additional economic
information contact Mr. William Anderson at (202) 260-5131.
SUPPLEMENTARY INFORMATION:Regulated Entities: Entities potentially
regulated by this action include:
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Examples of regulated
Category entities
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Industry.................................. Landfills regulated under
Subtitle C or Subtitle D of
RCRA that collect and
discharge landfill
generated wastewaters and
are not located at other
industrial or commercial
facilities.
State, municipal or tribal Government..... Landfills regulated under
Subtitle C or Subtitle D of
RCRA that collect and
discharge landfill
generated wastewaters and
are not located at other
industrial or commercial
facilities.
Federal Government........................ Landfills regulated under
Subtitle C or Subtitle D of
RCRA that collect and
discharge landfill
generated wastewaters and
are not located at other
industrial or commercial
facilities.
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The preceding table is not intended to be exhaustive, but rather
provides a guide for readers regarding entities likely to be regulated
by this action. This table lists the types of entities that EPA is now
aware could potentially be regulated by this action. Other types of
entities not listed in the table could also be regulated. To determine
whether your facility is regulated by this action, you should carefully
examine the applicability criteria in Sec. 445.02 of the proposed rule.
If you have questions regarding the applicability of this action to a
particular entity, consult the person listed in the preceding FOR
FURTHER INFORMATION CONTACT section.
Supporting Documentation
The regulations proposed today are supported by several major
documents:
1. ``Development Document for Proposed Effluent Limitations
[[Page 6427]]
Guidelines and Standards for the Landfills Category'' (EPA 821-R-97-
022). Hereafter referred to as the Technical Development Document,
presents EPA's technical conclusions concerning the proposal. EPA
describes, among other things, the data collection activities in
support of the proposal, the wastewater treatment technology options,
wastewater characterization, and the estimation of costs to the
industry.
2. ``Economic and Cost-Effectiveness Analysis for Proposed Effluent
Limitations Guidelines and Standards for the Landfills Category'' (EPA
821-B-97-005).
3. ``Statistical Support Document for Proposed Effluent Limitations
Guidelines and Standards for the Landfills Category'' (EPA 821-B-97-
006).
4. ``Environmental Assessment for Proposed Effluent Limitations
Guidelines and Standards for the Landfills Category'' (EPA 821-B-97-
007).
How To Obtain Supporting Documents
The Technical and Economic Development Documents can be obtained
through EPA's Home Page on the Internet, located at www.EPA.gov/OST/
rules. The documents are also available from the Office of Water
Resource Center, RC-4100, U.S. EPA, 401 M Street SW, Washington, D.C.
20460; telephone (202) 260-7786 for the voice mail publication request.
Table of Contents
I. Legal Authority
II. Background
A. Clean Water Act
B. Section 304(m) Requirements
III. Scope of the Proposed Regulation
IV. Regulatory History of the Landfills Category
A. RCRA Subtitle C
1. Land Disposal Restrictions
2. Minimum Technology Requirements
B. RCRA Subtitle D
V. Industry Profile
VI. Summary of EPA Activities & Data Gathering Efforts
A. Preliminary Data Summary for the Hazardous Waste Treatment
Industry
B. Survey Questionnaires
C. Wastewater Sampling and Site Visits
D. Additional Data Sources
VII. Development of Subcategorization Approach
A. Selection of Subcategorization Approach
B. Factors Considered for Basis of Subcategorization
VIII. Wastewater Characterization
A. Sources of Landfill Generated Wastewater
B. Wastewater Characterization
C. Wastewater Flows and Discharge
IX. Development of Effluent Limitations Guidelines and Standards
A. Description of Available Technologies
B. Technology Options Considered for Basis of Regulation
C. Development of Effluent Limitations
D. Treatment Systems Selected for Basis of Regulation
X. Costs and Impacts of Regulatory Alternatives
A. Methodology for Estimating Costs and Pollutant Reductions
Achieved by Treatment Technologies.
B. Costs of Compliance
C. Pollutant Reductions
XI. Economic Analysis
A. Introduction and Overview
B. Baseline Conditions
C. Methodology
D. Summary of Economic Impacts
1. Economic Impacts of Proposed BPT
2. Economic Impacts of Proposed BAT Option
3. Economic Impact of Proposed PSES
4. Economic Achievability of Proposed NSPS and PSNS
5. Firm Level Impacts
6. Community Impacts
7. Foreign Trade Impacts
E. Cost-Effectiveness Analysis
XII. Water Quality Analysis and Environmental Benefits
A. Introduction
B. Water Quality Impacts and Benefits
XIII. Non-water Quality Environmental Impacts
A. Air Pollution
B. Solid Waste Generation
C. Energy Requirements
XIV. Related Acts of Congress, Executive Orders, and Agency
Initiatives
A. Paperwork Reduction Act
B. Regulatory Flexibility Act
C. Unfunded Mandates Reform Act
D. Executive Order 12866 (OMB Review)
E. National Technology Transfer and Advancement Act
XV. Regulatory Implementation
A. Applicability
B. Upset and Bypass Provisions
C. Variances and Modifications
1. Fundamentally Different Factors Variances
2. Permit Modifications
3. Removal Credits
D. Relationship of Effluent Limitations to NPDES Permits &
Monitoring Requirements
E. Implementation for Facilities With Landfills in Multiple
Subcategories
F. Implementation for Contaminated Groundwater Flows
XVI. Solicitation of Data and Comments
A. Introduction and General Solicitation
B. Specific Data Requests and Comment Solicitations
Appendix A: Definitions, Acronyms, and Abbreviations Used in This
Notice
I. Legal Authority
These regulations are proposed under the authority of Sections 301,
304, 306, 307, 308, and 501 of the Clean Water Act, 33 U.S.C. 1311,
1314, 1316, 1317, 1318, and 1361.
II. Background
A. Clean Water Act
Congress adopted the Clean Water Act (CWA) to ``restore and
maintain the chemical, physical, and biological integrity of the
Nation's waters'' (Section 101(a), 33 U.S.C. 1251(a)). To achieve this
goal, the CWA prohibits the discharge of pollutants into navigable
waters except in compliance with the statute. The Clean Water Act
confronts the problem of water pollution on a number of different
fronts. Its primary reliance, however, is on establishing restrictions
on the types and amounts of pollutants discharged from various
industrial, commercial, and public sources of wastewater.
Congress recognized that regulating only those sources that
discharge effluent directly into the nation's waters would not be
sufficient to achieve the CWA's goals. Consequently, the CWA requires
EPA to promulgate nationally applicable pretreatment standards which
restrict pollutant discharges for those who discharge wastewater
indirectly through sewers flowing to publicly-owned treatment works
(POTWs) (Section 307(b) and (c), 33 U.S.C. 1317(b) and (c)). National
pretreatment standards are established for those pollutants in
wastewater from indirect dischargers which may pass through or
interfere with POTW operations. Generally, pretreatment standards are
designed to ensure that wastewater from direct and indirect industrial
dischargers are subject to similar levels of treatment. In addition,
POTWs are required to implement local treatment limits applicable to
their industrial indirect dischargers to satisfy any local requirements
(40 CFR 403.5).
Direct dischargers must comply with effluent limitations in
National Pollutant Discharge Elimination System (``NPDES'') permits;
indirect dischargers must comply with pretreatment standards. These
limitations and standards are established by regulation for categories
of industrial dischargers and are based on the degree of control that
can be achieved using various levels of pollution control technology.
1. Best Practicable Control Technology Currently Available (BPT)--Sec.
304(b)(1) of the CWA
In the guidelines for an industry category, EPA defines BPT
effluent limits for conventional, priority,1 and
[[Page 6428]]
non-conventional pollutants. In specifying BPT, EPA looks at a number
of factors. EPA first considers the cost of achieving effluent
reductions in relation to the effluent reduction benefits. The Agency
also considers: the age of the equipment and facilities, the processes
employed and any required process changes, engineering aspects of the
control technologies, non-water quality environmental impacts
(including energy requirements), and such other factors as the Agency
deems appropriate (CWA 304(b)(1)(B)). Traditionally, EPA establishes
BPT effluent limitations based on the average of the best performances
of facilities within the industry of various ages, sizes, processes or
other common characteristic. Where, however, existing performance is
uniformly inadequate, EPA may require higher levels of control than
currently in place in an industrial category if the Agency determines
that the technology can be practically applied.
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\1\ In the initial stages of EPA CWA regulation, EPA efforts
emphasized the achievement of BPT limitations for control of the
``classical'' pollutants (e.g., TSS, pH, BOD5). However,
nothing on the face of the statute explicitly restricted BPT
limitation to such pollutants. Following passage of the Clean Water
Act of 1977 with its requirement for points sources to achieve best
available technology limitations to control discharges of toxic
pollutants, EPA shifted its focus to address the listed priority
pollutants under the guidelines program. BPT guidelines continue to
include limitations to address all pollutants.
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2. Best Conventional Pollutant Control Technology (BCT)--Sec. 304(b)(4)
of the CWA
The 1977 amendments to the CWA required EPA to identify effluent
reduction levels for conventional pollutants associated with BCT
technology for discharges from existing industrial point sources. In
addition to other factors specified in Section 304(b)(4)(B), the CWA
requires that EPA establish BCT limitations after consideration of a
two part ``cost-reasonableness'' test. EPA explained its methodology
for the development of BCT limitations in July 1986 (51 FR 24974).
Section 304(a)(4) designates the following as conventional
pollutants: biochemical oxygen demand (BOD5), total
suspended solids (TSS), fecal coliform, pH, and any additional
pollutants defined by the Administrator as conventional. The
Administrator designated oil and grease as an additional conventional
pollutant on July 30, 1979 (44 FR 44501).
3. Best Available Technology Economically Achievable (BAT)--Sec.
304(b)(2) of the CWA
In general, BAT effluent limitations guidelines represent the best
economically achievable performance of plants in the industrial
subcategory or category. The factors considered in assessing BAT
include the cost of achieving BAT effluent reductions, the age of
equipment and facilities involved, the process employed, potential
process changes, and non-water quality environmental impacts, including
energy requirements. The Agency retains considerable discretion in
assigning the weight to be accorded these factors. Unlike BPT
limitations, BAT limitations may be based on effluent reductions
attainable through changes in a facility's processes and operations. As
with BPT, where existing performance is uniformly inadequate, BAT may
require a higher level of performance than is currently being achieved
based on technology transferred from a different subcategory or
category. BAT may be based upon process changes or internal controls,
even when these technologies are not common industry practice.
4. New Source Performance Standards (NSPS)--Sec. 306 of the CWA
NSPS reflect effluent reductions that are achievable based on the
best available demonstrated control technology. New facilities have the
opportunity to install the best and most efficient production processes
and wastewater treatment technologies. As a result, NSPS should
represent the most stringent controls attainable through the
application of the best available control technology for all pollutants
(i.e., conventional, nonconventional, and priority pollutants). In
establishing NSPS, EPA is directed to take into consideration the cost
of achieving the effluent reduction and any non-water quality
environmental impacts and energy requirements.
5. Pretreatment Standards for Existing Sources (PSES)--Sec. 307(b) of
the CWA
PSES are designed to prevent the discharge of pollutants that pass
through, interfere-with, or are otherwise incompatible with the
operation of publicly-owned treatment works (POTW). The CWA authorizes
EPA to establish pretreatment standards for pollutants that pass
through POTWs or interfere with treatment processes or sludge disposal
methods at POTWs. Pretreatment standards are technology-based and
analogous to BAT effluent limitations guidelines.
The General Pretreatment Regulations, which set forth the framework
for the implementation of categorical pretreatment standards, are found
at 40 CFR Part 403. Those regulations contain a definition of pass-
through that addresses localized rather than national instances of
pass-through and establish pretreatment standards that apply to all
non-domestic dischargers. See 52 FR 1586, January 14, 1987.
6. Pretreatment Standards for New Sources (PSNS)--Sec. 307(b) of the
CWA
Like PSES, PSNS are designed to prevent the discharges of
pollutants that pass through, interfere-with, or are otherwise
incompatible with the operation of POTWs. PSNS are to be issued at the
same time as NSPS. New indirect dischargers have the opportunity to
incorporate into their plants the best available demonstrated
technologies. The Agency considers the same factors in promulgating
PSNS as it considers in promulgating NSPS.
B. Section 304(m) Requirements
Section 304(m) of the CWA, added by the Water Quality Act of 1987,
requires EPA to establish schedules for (1) reviewing and revising
existing effluent limitations guidelines and standards (``effluent
guidelines'') and (2) promulgating new effluent guidelines. On January
2, 1990, EPA published an Effluent Guidelines Plan (55 FR 80) that
established schedules for developing new and revised effluent
guidelines for several industry categories. One of the industries for
which the Agency established a schedule was the Centralized Waste
Treatment Industry.
The Natural Resources Defense Council (NRDC) and Public Citizen,
Inc. filed suit against the Agency, alleging violation of Section
304(m) and other statutory authorities requiring promulgation of
effluent guidelines (NRDC et al. v. Reilly, Civ. No. 89-2980 (D.D.C.)).
Under the terms of a consent decree dated January 31, 1992, which
settled the litigation, EPA agreed, among other things, to propose
effluent guidelines for the ``Landfills and Industrial Waste
Combusters'' category 2 by December 1995 and take final
action on these effluent guidelines by December 1997. On February 4,
1997, the court approved modifications to the Decree which revise the
deadlines to November 1997 for proposal and November 1999 for final
action. EPA provided notice of these modifications on February 26,
1997, at 62 FR 8726. Although the Consent Decree lists ``Landfills and
Industrial Waste Combusters'' as a single entry, EPA is publishing
separate rulemaking
[[Page 6429]]
proposals for Industrial Waste Combusters and for Landfills.
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\2\ In the 1990 304(m) plan and the 1992 Decree, the category
name was ``Hazardous Waste Treatment, Phase II'', subsequently
renamed as ``Landfills and Industrial Waste Combusters.''
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III. Scope of the Proposed Regulation
EPA is today proposing effluent limitations guidelines and
pretreatment standards for wastewater discharges associated only with
the operation and maintenance of landfills regulated under Subtitles C
and D of the Resource Conservation and Recovery Act (RCRA).3
EPA's proposal would not apply to wastewater discharges associated with
the operation and maintenance of land application or treatment units,
surface impoundments, underground injection wells, waste piles, salt
dome or bed formations, underground mines, caves or corrective action
units.4 Additionally, this guideline would not apply to
waste transfer stations, or any wastewater not directly attributed to
the operation and maintenance of Subtitle C or Subtitle D landfill
units. Consequently, wastewaters such as those generated in off-site
washing of vehicles used in landfill operations are not within the
scope of this guideline.
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\3\ EPA's Subtitle C and Subtitle D regulations define
``landfill''. See 40 CFR 257.2, 258.2 (``municipal solid waste
landfill'') and 260.10. Permitted subtitle C landfills are
authorized to accept hazardous wastes as defined in 40 CFR Part 261.
Subtitle D landfills are authorized to receive municipal, commercial
or industrial waste that is not hazardous (or is hazardous waste
excluded from regulation under Subtitle C). Details of the RCRA
regulatory requirements are provided below at Section [IV] .
\4\ These terms are defined at 40 CFR 257.2 and 260.10.
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The wastewater flows which are covered by the rule include
leachate, gas collection condensate, drained free liquids, laboratory-
derived wastewater, contaminated storm water and contact washwater from
truck exteriors and surface areas which have come in direct contact
with solid waste at the landfill facility. Groundwater, however, which
has been contaminated by a landfill and is collected, treated, and
discharged is excluded from this guideline. A discussion of the
exclusion for contaminated groundwater flows is included in Section
[VIII] of this notice. A description of sources of wastewater in the
landfills category is also provided in Section [VIII].
EPA initially considered development of effluent guidelines to
address any landfill discharging directly to the surface waters of the
United States or introducing pollutants into a POTW. Consequently,
EPA's technical evaluation for the proposal included an assessment of
all landfill facilities which collect wastewater as a result of
landfilling operations. However, EPA has decided not to include within
the scope of this proposal landfill facilities operated in conjunction
with other industrial or commercial operations which only receive waste
from off-site facilities under the same corporate structure (intra-
company facility) and/or receive waste generated on-site (captive
facility) so long as the wastewater is commingled for treatment with
other non-landfill process wastewaters. A landfill which accepts off-
site waste from a company not under the same ownership as the landfill
would not be considered a captive or intracompany facility and would be
subject to the Landfills category effluent guideline when promulgated.
EPA has decided not to include these facilities within the scope of
this proposed regulation for the following reasons.
First, EPA has preliminarily concluded that the wastewater
generated by landfill operations at most of the captive and
intracompany facilities are already subject to categorical effluent
limitations (or pretreatment standards). The evidence EPA has reviewed
to date supports the conclusion that these wastewater flows were either
assessed and evaluated for the effluent limitations guideline
applicable to the facility, or are the subject of Best Professional
Judgment (BPJ) or Combined Wastestream Formula limits established by
the permit writer or Control Authority.
The second reason EPA believes that it should exclude such
landfills from this guideline is because landfill wastewaters at
captive and intracompany landfills represent a very small portion of
the wastewater flows treated at their wastewater treatment facilities
(often less than one percent and typically less than three percent). In
these circumstances, so long as the facilities combine the relatively
small quantities of landfill wastewater with their other industrial
process wastewater for treatment, there is little likelihood that the
pollutants of concern in the landfill leachate will escape treatment.
An additional factor lends intuitive support to this conclusion. It is
likely that leachate from on-site landfills at industrial operations
will reflect a pollutant profile similar to the facility's industrial
process wastewater. EPA believes that landfill wastewaters generated at
such facilities have a similar pollutant profile to the wastewater
generated in the industrial operation. For example, the leachate from a
landfill at a facility subject to the Petroleum Refining guideline will
tend to be characterized by high organic loads, while the leachate from
a facility regulated under the Nonferrous Metals guideline will be
characterized by metal loadings. Consequently, based on the information
EPA has reviewed to date, the Agency believes that the wastewater
treatment currently in place at such industrial facilities is likely to
treat the majority of the pollutants found in leachate at that
facility. However, the Agency has only limited information on leachate
quality at landfills associated with industrial operations.
Accordingly, EPA requests additional data and solicits comments and
data regarding its conclusion that landfill leachate at such facilities
is likely to be treated effectively in the industrial wastewater
treatment system and that additional effluent guidelines and
categorical pretreatment standards are not necessary.
A third reason supporting exclusion of such facilities from this
guideline is EPA's conclusion that the pollutants in on-site landfill
wastewaters are receiving adequate treatment that is at least
equivalent to that proposed here. EPA has compared the wastewater
treatment technologies employed at these facilities to the treatment
technologies being proposed for BPT/BAT and PSES for independently,
commercially or municipally operated Subtitle C and D landfills. This
assessment suggests that, in most cases, treatment for regulated
pollutants being achieved at such facilities is comparable to those
being proposed here.
Finally, EPA has also reviewed individual NPDES permits for captive
and intracompany facilities to verify its preliminary conclusion that
it may exclude such facilities from the scope of this regulation
without jeopardizing receiving waters. The Agency has identified no
captive or intracompany landfills that are not commingling the landfill
wastewater for treatment with other wastewater at the facility. This
review indicates that, for the most part, these landfill wastestreams
are mixed with categorical wastes for treatment and subject to
limitations comparable to those being considered here. Given these
facts, EPA has concluded preliminarily that it should not include such
captive or intracompany facilities within the scope of today's proposed
action. However, EPA is requesting comment on its approach.5
The Agency is particularly eager for data concerning
[[Page 6430]]
treatment of such wastestreams at categorical and other facilities.
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\5\ EPA acknowledges that its conclusions are tentative and not
without uncertainty. A number of the facility operators identified
themselves as subject to multiple categories. EPA applied its best
judgment in many circumstances to determining the probable handling
of the landfill waste streams. EPA is specifically soliciting data
and other information on this issue.
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Based on its survey for this guideline, EPA identified over 200
captive and intracompany facilities with on-site landfills. A majority
of these landfills are found at industrial facilities that are or will
be subject to three effluent guidelines: Pulp and Paper (40 CFR Part
430), Centralized Waste Treatment (proposed 40 CFR Part 437, 60 FR
5464, January 27, 1995), or Organic Chemicals, Plastics and Synthetic
Fibers (OCPSF) (40 CFR Part 414). In addition, EPA identified
approximately 30 landfills subject to one or more of the following
categories: Nonferrous Metals Manufacturing (40 CFR Part 421),
Petroleum Refining (40 CFR Part 419), Timber Products Processing (40
CFR Part 429), Iron and Steel Manufacturing (40 CFR Part 420),
Transportation Equipment Cleaning (new category to be proposed in
1998), and Pesticide Manufacturing (40 CFR Part 455). EPA did not,
however, specifically consider the flows associated with this landfill
leachate in the development of these guidelines.
Industry supplied data estimates that there are over 118 Pulp and
Paper facilities with on-site landfills and that over 90 percent
commingle landfill leachate with process wastewater for treatment on-
site. Treatment at these facilities generally involves secondary
biological treatment. The wastewater flow originating from landfills
typically represents less than one percent of the total flow through
the facilities' wastewater treatment plant and in no case exceeds three
percent of the treated flow. Additionally, approximately six percent of
the pulp and paper mills send landfill generated wastewater to a POTW
along with process wastewater.
Based on this information, EPA has preliminarily concluded that
landfill-generated wastewater at pulp and paper mill facilities will
typically receive biological treatment equivalent to that proposed
today for stand-alone landfills and consequently should be excluded
from the scope of this regulation. This conclusion is based on several
factors. Because landfill leachate is a regulated flow under the
current permitting guidelines, permit writers must develop limits for
landfill wastewater exercising their Best Professional Judgment (BPJ).
Given the small volumes of landfill generated wastewaters and the fact
that the treatment in place for industrial wastewaters will adequately
treat the constituents typically found in landfill leachate, EPA
believes that BPJ limits are likely to adequately control these
discharges.
Based on responses to the 1992 Waste Treatment Industry: Landfills
Questionnaire, EPA estimates that there are more than 30 facilities
subject to the Organic Chemicals, Plastics and Synthetic Fibers
guideline with on-site landfills.6 At OCPSF facilities with
on-site landfills, landfill leachate typically represents less than one
percent of the industrial flow at the facility, in no case exceeds six
percent of the flow and is typically commingled with process wastewater
for treatment. EPA specifically considered landfill leachate in the
development of the OCPSF guideline, although it is not specifically
identified as a regulated flow in the applicability section of the
rule. The development document for the guidelines discusses landfill
leachate as one of the ancillary flows often treated at OCPSF
facilities. Further, EPA has preliminarily concluded that the character
of the landfill wastewater is similar to that being treated at the
industrial operation and that landfill-generated wastewater will
typically receive treatment equivalent to that proposed today for
stand-alone landfills. Therefore, EPA concludes that so long as the
landfill-associated discharge is subject to the same limits as the
industrial operation that an appropriate level of control is being
achieved.
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\6\ Responses to the Questionnaire show that many OCPSF
facilities also collect landfill leachate as well as contaminated
groundwater. In the case of contaminated groundwater, these flows
are addressed through corrective actions programs at the site and
have not been considered for regulation under this guideline. The
exclusion for contaminated groundwater is further discussed later in
this section. Typically, contaminated groundwater is treated
separately from other industrial wastewaters.
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As previously explained, on-site generated landfill wastewater that
is commingled with other industrial wastewater at an industrial site is
not included within the scope of the proposal. Thus, under the proposed
approach, wastewater discharges from landfills located at Centralized
Waste Treatment (CWT) facilities would be excluded from this regulation
so long as the wastewater is commingled for treatment. In the Agency's
current thinking, the categorical limitations and standards to be
established for the Centralized Waste Treatment Category and codified
at 40 CFR Part 429, would specifically cover landfill generated
wastewater at CWT facilities (60 FR 5464, note: EPA currently intends
to publish a reproposed CWT rule in 1998 and promulgate the final rule
in 1999). Given the pollutant characteristics of the landfill leachate,
landfill leachate flows would likely be subject to the CWT effluent
limitations established under the Organics Subcategory.
Further, under this proposal, a landfill facility that accepts
wastewater from off-site for treatment may, in some circumstances,
itself be subject to either landfill limitations or CWT limitations.
This will depend on whether the wastewater treated in its treatment
system is exclusively landfill-generated wastewater or not. For
example, if a landfill facility accepts any wastewater from a non-
landfill source for treatment in its wastewater treatment system, then
that treatment system is to be considered a CWT and would be subject to
the guidelines and standards to be codified at 40 CFR Part 429.
However, a landfill facility may accept wastewater for treatment that
is generated off-site from off-site landfills. If a landfill facility
accepts wastewater from landfill generated sources, and only from
landfill generated sources, then that facility is subject to the
effluent guidelines and standards proposed to be established for the
landfills category. The final guideline for CWT will modify the
definition of a CWT to clarify this applicability issue.
IV. Regulatory History of the Landfills Category
Depending on the type of wastes disposed at a landfill, the
landfill may be subject to regulation and permitting under either
Subtitle C or Subtitle D of RCRA. Subtitle C facilities receive wastes
that are identified or listed as hazardous wastes under EPA
regulations. Subtitle D landfills can accept wastes which are not
required to be sent to Subtitle C facilities. The following sections
outline some of the key regulations that have been developed to control
the environmental impacts of Subtitle C and Subtitle D landfills.
A. RCRA Subtitle C
Subtitle C of RCRA directs EPA to promulgate regulations to protect
human health and the environment from the improper management of
hazardous wastes from ``cradle-to-grave''. Among EPA's key duties under
RCRA Subtitle C is the requirement to promulgate regulations
identifying the characteristics of hazardous waste and listing
particular hazardous wastes. (Section 3001). EPA must also promulgate
standards that apply to generators and transporters of hazardous waste
as well as standards for the owners and operators of hazardous waste
treatment, storage and disposal (TSD) facilities (Sections 3002-3004).
In addition, RCRA Section 3005 required
[[Page 6431]]
EPA to establish a permitting system for each owner or operator of a
TSD facility.
These regulations establish a system for tracking the disposal of
hazardous wastes and performance design requirements for landfills
accepting hazardous waste. RCRA Subtitle C hazardous waste regulations
apply to landfills that presently accept hazardous wastes or have
accepted hazardous waste at any time after November 19, 1980.
1. Land Disposal Restrictions
The Hazardous and Solid Waste Amendments (HSWA) to the Resource
Conservation and Recovery Act (RCRA), enacted on November 8, 1984,
largely prohibit the land disposal of untreated hazardous wastes. Once
a hazardous waste is prohibited from land disposal, the statute
provides only two options for legal land disposal: (1) Meet EPA-
established treatment standard for the waste prior to land disposal, or
(2) dispose of the waste in a land disposal unit that has been found to
satisfy the statutory no migration test. A no migration unit is one
from which there will be no migration of hazardous constituents for as
long as the waste remains hazardous (RCRA Sections 3004
(d),(e),(g)(5)).
Under Section 3004, the treatment standards that EPA develops may
be expressed as either constituent concentration levels or as specific
methods of treatment. The criteria for these standards is that they
must substantially diminish the toxicity of the waste or substantially
reduce the likelihood of migration of hazardous constituents from the
waste so that short-term and long-term threats to human health and the
environment are minimized (RCRA Section 3004(m)(1)). For purposes of
the restrictions, the RCRA program defines land disposal to include,
among other things, any placement of hazardous waste in a landfill.
Land disposal restrictions are published in 40 CFR Part 268.
EPA has used hazardous waste treatability data as the basis for
land disposal restrictions standards. First, EPA has identified Best
Demonstrated Available Treatment Technology (BDAT) for each listed
hazardous waste. BDAT is that treatment technology that EPA finds to be
the most effective treatment for a waste which is also readily
available to generators and treaters. In some cases EPA has designated
as BDAT for a particular waste stream a treatment technology shown to
have successfully treated a similar but more difficult to treat waste
stream. This ensured that the land disposal restrictions standards for
a listed waste stream were achievable since they always reflected the
actual treatability of the waste itself or of a more refractory waste.
As part of the Land Disposal Restrictions (LDR), Universal
Treatment Standards (UTS) were promulgated as part of the RCRA phase
two final rule (July 27,1994). The UTS are a series of concentrations
for wastewaters and non-wastewaters that provide a single treatment
standard for each constituent. Previously, the LDR regulated
constituents according to the identity of the original waste; thus,
several numerical treatment standards might exist for each constituent.
The UTS simplified the standards by having only one treatment standard
for each constituent in any waste residue.
The LDR treatment standards established under RCRA may differ from
the Clean Water Act effluent guidelines proposed here today both in
their format and in the numerical values set for each constituent. The
differences result from the use of different legal criteria for
developing the limits and resulting differences in the technical and
economic criteria and data sets used for establishing the respective
limits.
There may be differences in how standards are expressed for the LDR
and effluent guidelines. For example, LDR may establish a single
concentration limit for particular waste hazardous constituents whereas
the effluent guidelines establish monthly and daily average limits.
Additionally, the effluent guidelines provide for several types of
discharge, including new versus existing sources and indirect versus
direct discharge.
The differences in numerical limits established under the Clean
Water Act may differ not only from LDR and UTS but also from point-
source category to point-source category (e.g., Electroplating, 40 CFR
Part 413; and Metal Finishing, 40 CFR Part 433). The effluent
guidelines limitations and standards are industry-specific,
subcategory-specific, and technology-based. The numerical limits are
typically based on different data sets that reflect the performance of
specific wastewater management and treatment practices. Differences in
the limits reflect differences in the statutory factors that the
Administrator is required to consider in developing technically and
economically achievable limitations and standards--manufacturing
products and processes (which, for landfills involves types of waste
disposed), raw materials, wastewater characteristics, treatability,
facility size, geographic location, age of facility and equipment, non-
water quality environmental impacts, and energy requirements. A
consequence of these differing approaches is that similar or identical
waste streams are regulated at different levels dependent on the
receiving body of the wastewater, e.g. a POTW, a surface water, or a
land disposal facility.
2. Minimum Technology Requirements
In order to further protect human health and the environment from
the adverse affects of hazardous waste disposed in landfills, the 1984
Hazardous and Solid Waste Amendments (HSWA) to RCRA established minimum
technology requirements for landfills receiving hazardous waste. These
provisions required the installation of double liners and leachate
collection systems at new landfills, replacements of existing units,
and lateral expansions of existing units. HSWA also required all
hazardous waste landfills to install groundwater monitoring wells by
November 8, 1987. Performance regulations governing the operation of
hazardous waste landfills are included in 40 CFR Parts 264 and 265.
B. RCRA Subtitle D
Landfills managing non-hazardous wastes are regulated under the
RCRA Subtitle D program. A brief summary of these RCRA Subtitle D
regulations is provided below.
40 CFR Part 257, Subpart A Criteria
EPA promulgated these criteria on September 13, 1979 (44 FR 53460)
under the authority of RCRA Sections 1008(a) and 4004(a) and Sections
405(d) and (e) of the Clean Water Act. These criteria apply to all
solid waste disposal facilities and practices. However, certain
facilities and practices are not covered by the criteria, such as
agricultural wastes returned to the soil as fertilizers or soil
conditioners; overburden resulting from mining operations; land
application of domestic sewage or treated domestic sewage; hazardous
waste disposal facilities which are subject to regulations under RCRA
Subtitle C (discussed below); municipal solid waste landfills that are
subject to the revised criteria in 40 CFR Part 258 (discussed below);
and use or disposal of sewage sludge on the land when the sewage sludge
is used or disposed in accordance with 40 CFR Part 503 (See 40 CFR Part
257.1(c)(1)-(11)).
The criteria include general environmental performance standards
addressing eight major areas: flood plains, protection of endangered
species, protection of surface water,
[[Page 6432]]
protection of groundwater, limitations on the land application of solid
waste, periodic application of cover to prevent disease vectors, air
quality standards (prohibition against open burning), and safety
practices ensuring protection from explosive gases, fires, and bird
hazards to airports. Facilities which fail to comply with any of these
criteria are considered open dumps, which are prohibited by RCRA
Section 4005. Those facilities which meet the criteria are considered
sanitary landfills under RCRA Section 4004(a).
40 CFR Part 258 Revised Criteria for Municipal Solid Waste
Landfills (MSWLFs)
On October 9, 1991, EPA promulgated revised criteria for MSWLFs in
accordance with the authority provided in RCRA Sections 1008(a)(3),
4004(a), 4010 and CWA Sections 405(d) and (e) (see
56 FR 50978). Under the terms of these revised criteria, MSWLFs are
defined to mean a discrete area of land or an excavation that receives
household waste, and is not a land application unit, surface
impoundment, injection well, or waste pile, as those terms are defined
in 40 CFR 257.2 and 258.2. A MSWLF unit also may receive other types of
RCRA Subtitle D wastes, such as commercial solid waste, nonhazardous
sludge, and industrial solid waste. Such a landfill may be publicly or
privately owned. A MSWLF unit may be a new unit, existing MSWLF unit or
a lateral expansion.
The MSWLF revised criteria include location standards (Subpart B),
operating criteria (Subpart C), design criteria (Subpart D),
groundwater monitoring and corrective action (Subpart E), closure and
post-closure care criteria (Subpart F), and financial assurance
requirements (Subpart G). The design criteria provide that new MSWLF
units and lateral expansions of existing units (as defined in Section
258.2) must be constructed in accordance with either (1) a design
approved by a Director of a State whose MSWLF permit program has been
approved by EPA and which satisfies a performance standard to ensure
that unacceptable levels of certain chemicals do not migrate beyond a
specified distance from the landfill (Sections 258.40(a)(1), (c), (d),
Table 1) or (2) a composite liner and a leachate collection system
(Sections 258.40(a)(2), (b)). The groundwater monitoring criteria
generally require owners or operators of MSWLFs to monitor groundwater
for contaminants and generally implement a corrective action remedy
when monitoring indicates that a groundwater protection standard has
been exceeded. However, certain small MSWLFs located in arid or remote
locations are exempt from both design and groundwater monitoring
requirements. The closure standards require that a final cover be
installed to minimize infiltration and erosion. The post-closure
provisions generally require, among other things, that groundwater
monitoring continue and that the leachate collection system be
maintained and operated for 30 years after the MSWLF is closed. The
Director of an approved State may increase or decrease the length of
the post-closure period.
Again, as is the case with solid waste disposal facilities which
fail to meet the open dumping criteria in 40 CFR Part 257, Subpart A,
MSWLFs which fail to satisfy the revised criteria in Part 258
constitute open dumps (40 CFR 258.1(h)). All solid waste disposal
facilities, i.e., MSWLFs, that are subject to the requirements in the
Part 258 revised criteria and which collect and discharge landfill-
generated waste waters are included in this category.
40 CFR Part 257, Subpart B CESQG Revised Criteria
A Conditionally Exempt Small Quantity Generator (CESQG) is
generally defined as one who generates no more than 100 kilograms of
hazardous waste per month in a calendar year (40 CFR 261.5(a)). Such
CESQGs (with certain exceptions) are not subject to RCRA Subtitle C
requirements. However, on July 1, 1996, EPA (1) amended Part 257 to
establish criteria that must be met by non-municipal, non-hazardous
solid waste disposal units that receive CESQG waste and (2) established
separate management and disposal standards (in 40 CFR 261.5(f)(3) and
(g)(3)) for those who generate CESQG waste (see 61 FR 342169). The
CESQG revised criteria for such disposal units include location
standards, groundwater monitoring, and corrective action requirements.
V. Industry Profile
The growth of the landfills industry is a direct result of RCRA and
subsequent EPA and State regulation that establish the conditions under
which solid waste may be disposed. The adoption of increased control
measures required by RCRA has had a number of ancillary effects.
The RCRA requirements have affected the landfill industry in
different ways. On the one hand, it has forced many landfills to close
because they lacked adequate on-site controls to protect against
migration of hazardous constituents in the landfill, and it was not
economical to upgrade the landfill facility. As a result, a large
number of landfills, especially facilities serving small populations,
have closed rather than incur the significant expense of upgrading.
Conversely, large landfill operations have taken advantage of
economies of scale by serving wide geographic areas and accepting an
increasing portion of the nation's solid waste. For example, responses
to EPA's Waste Treatment Industry Survey indicated that 75 percent of
the nation's municipal solid waste was deposited in large landfills
representing only 25 percent of the landfill population.
EPA has identified several trends in the waste disposal industry
that may increase the quantity of leachate produced by landfills. More
stringent RCRA regulation and the restrictions on the management of
wastes have increased the amount of waste disposed at landfills as well
as the number of facilities choosing to send wastes off-site to
commercial facilities in lieu of pursuing on-site management options.
This will increase treated leachate discharges from the nation's
landfills, thus potentially putting at risk the integrity of the
nation's waters. Further, as a result of the increased number of
leachate collection systems, the volumes of leachate requiring
treatment and disposal has greatly increased.
EPA identified approximately 11,000 landfill facilities located
throughout the country in 1992. Out of the 11,000 facilities, EPA has
determined that the vast majority of these facilities either are closed
or do not generate wastewaters that EPA is proposing for regulation.
Based on survey responses, EPA believes that 164 facilities would be
affected by this proposed regulation.
In the case of landfills subject to regulation under Subtitle D,
EPA projects that there are 158 facilities which discharge in-scope
wastewater directly to receiving streams and which may be affected by
this proposal. EPA estimates that there are 762 facilities which
collect in-scope wastewaters but discharge indirectly to a POTW and
would not be affected by this proposal because EPA is not proposing to
regulate indirect discharges from non-hazardous, Subtitle D landfills.
There are an additional 343 facilities which collect in-scope
wastewaters but do not discharge to surface waters or to POTWs, and are
also not affected by this proposal. The means for disposing of their
wastewaters include hauling off-site to a centralized waste treatment
facility, evaporation, recirculation back to the landfill, and land
application.
[[Page 6433]]
With respect to landfills subject to regulation under Subtitle C,
EPA estimates that there are six hazardous landfill facilities which
discharge indirectly to POTWs that may be affected by this proposal.
EPA estimated that there are no hazardous landfills discharging
directly to surface waters. EPA estimates that there are 141 hazardous
landfills which collect in-scope wastewaters but do not discharge
wastewater to surface waters or to a POTW. Methods of wastewater
disposal include hauling wastewater off-site to a centralized waste
treatment facility, underground injection, and solidification.
Additionally, EPA estimates that there are more than 250 industrial
facilities which contain landfills but would be excluded from this
regulation as a result of the factors discussed in Section [III].
VI . Summary of EPA Activities and Data Gathering Efforts
This section describes the sources of data used by EPA in support
of this proposal.
A. Preliminary Data Summary for the Hazardous Waste Treatment Industry
EPA's initial effort to develop effluent limitations guidelines and
pretreatment standards for the waste treatment industry began in 1986.
The Agency looked at a range of facilities, including landfills, that
received waste from off-site for treatment, recovery or disposal. The
purpose of this study was to develop information to characterize the
hazardous waste treatment industry, its operations, and pollutant
discharges to the nation's waters. EPA published the results of its
examination of the industry in the ``Preliminary Data Summary for the
Hazardous Waste Treatment Industry'' in 1989 (EPA 440/1-89-100). This
report focused on three types of hazardous waste treatment industries:
landfills, incinerators with wet scrubbers, and aqueous hazardous waste
treaters.
After a thorough analysis of the landfill data presented in the
Preliminary Data Summary, EPA decided it should develop an effluent
guidelines regulation for the landfills category. EPA's decision to
develop effluent limitations guidelines was based on the Preliminary
Data Summary's assessment of the current and future trends in the
landfill industry, its analysis of the concentrations of pollutants in
the raw leachate, and the study's discussion on the treatment and
control technologies available for effective pollution reduction in
landfill leachate.
The Preliminary Data Summary outlined several trends in the waste
disposal industry that are likely to affect the amount of leachate
produced by landfills and leachate characteristics. The summary
projected an increase in the amount of waste disposed at landfills as a
result of more stringent regulations and restrictions on certain waste
management practices. The increase in the number of facilities choosing
to send wastes off-site to commercial facilities in lieu of pursuing
on-site management options ultimately increases the amount of leachate
discharged each year from the nation's landfills, thus potentially
putting at risk the integrity of the nation's waters.
Another trend identified in the Preliminary Data Summary is the
installation of leachate collection systems. Many of these systems are
a result of current RCRA regulations which require leachate collection
systems in hazardous landfills or federal regulations requiring them in
municipal landfills. As a result of the increased number of leachate
collection systems, the volumes of leachate requiring treatment and
disposal has greatly increased. This increased volume of leachate was
another reason EPA felt it necessary to propose an effluent guideline
for landfills.
B. Survey Questionnaires
A major source of information and data used in developing effluent
limitations guidelines and standards was industry responses to detailed
technical and economic questionnaires, and the subsequent Detailed
Monitoring Questionnaires (DMQs) distributed by EPA under the authority
of Section 308 of the Clean Water Act. For the Landfills industry, the
data collection process was done in several steps. First, EPA
identified a population of 595 Subtitle C landfills and 10,330 Subtitle
D landfills in the country.
Second, a screener survey was developed to collect initial
information on all possible landfill sites in the U.S. and to update
information on ownership and facility contacts. Screener surveys were
mailed to all 595 Subtitle C landfills and to 4401 Subtitle D landfills
(approximately 43 percent). Information collected by the screener
surveys included:
mailing address;
landfill type, including types and amount of solid waste
disposed;
landfill capacity;
wastewater generation rates as a result of landfill
operations, including leachate, gas condensate, and contaminated
groundwater;
regulatory classification;
ownership status;
discharge status;
monitoring practices; and
treatment technology.
Of the 4,996 screener questionnaires mailed, there were 3,628
respondents. Of these, 3,581 were of sufficient quality to be used for
data analysis. Of these, EPA identified 1,024 landfills that generate
and collect one or more types of in-scope wastewaters.
Once the information from the screener surveys was tabulated and
analyzed, EPA then developed a technical Detailed Questionnaire to
obtain more information from the in-scope facilities identified in the
screener surveys.
In determining which in-scope facilities should receive the
technical Detailed Questionnaire, EPA weighted the list toward those
landfills with wastewater treatment facilities in place. All in-scope
facilities selected fell into the following four categories:
1. Questionnaires were sent to all commercial, municipal, or
government facilities identified from the screener that had wastewater
treatment (for their landfill generated wastewaters) and were direct or
indirect dischargers.
2. A 25 percent sample of landfills were selected from the list of
commercial, municipal, or government facilities identified from the
screener that had wastewater treatment, but were zero or alternative
dischargers (i.e., do not discharge to a POTW or to a surface water).
3. A 40 percent sample of landfills were selected from the list of
non-commercial private (captive or intra-company) facilities identified
from the screener that had wastewater treatment.
4. A 10 percent sample of landfills were selected from the list of
facilities identified from the screener that collected and discharged
in-scope wastewater, but did not have wastewater treatment.
This selection criteria resulted in a mailing of the Detailed
Questionnaires to 252 in-scope facilities. The Detailed Questionnaires
solicited technical and economic information on landfill operations,
employment, revenue, wastewater generation, wastewater treatment, and
wastewater monitoring data.
Of the 252 recipients, 220 responded with sufficient technical data
to be included in the final EPA Detailed Questionnaire database.
In addition to the Detailed Questionnaire, EPA also requested
detailed wastewater monitoring information from 27 in-scope facilities
from the questionnaire mailing list. These facilities were selected
based
[[Page 6434]]
upon their responses to the Detailed Questionnaire. EPA reviewed each
facility's monitoring summary provided in the questionnaire, discharge
permit requirements, and their on-site treatment technologies. From
these responses, EPA determined that 27 facilities could provide useful
information on technology performance and pollutant removals.
The selected facilities were requested to send analytical data
(1992, 1993, and 1994 annual data) on daily equalized influent to their
wastewater treatment system, as well as effluent data from the
treatment system. The three years of analytical data were used to help
EPA calculate the variability factors (Section IX of today's notice)
used in determining the industry effluent limits. Analytical data for
intermediate waste treatment sampling points were also requested for
some facilities. In this manner, EPA was able to obtain performance
information across individual treatment units in addition to the entire
treatment process.
EPA also conducted a thorough review of each DMQ response to ensure
that the data provided was representative of the facility's treatment
system. EPA collected data from 24 semi-continuous and continuous
treatment systems and two batch treatment systems.
C. Wastewater Sampling and Site Visits
EPA conducted wastewater characterization site visits at 15
landfill facilities. The purpose of these visits was to collect
information on the facility's landfilling operations and collect
influent raw wastewater samples to help characterize the Landfill
industry. The selection of facilities was based on the responses to the
Detailed Questionnaire on type of landfill (e.g., construction and
demolition, ash, sludge, industrial, and hazardous). EPA visited
facilities from as broad a cross section of the industry as possible.
EPA spent one day at each landfill. During the site visits, EPA
collected information on the types of waste accepted, acceptance
criteria, and landfill operating practices. EPA emphasized obtaining
wastewater characterization information, such as the type, source, and
quantity of raw wastewaters generated, and wastewater collection
methods employed. Grab samples of the untreated wastewater were
collected from each landfill and the data that resulted from these
samples were used in the characterization of the Landfills industry.
EPA conducted engineering site visits at 19 facilities. The purpose
of these visits was to evaluate each facility as a potential week-long
sampling candidate. The selection of these facilities was based on the
responses to the Detailed Questionnaire on types of wastewater
treatment on site. Facilities selected for engineering site visits
employed various types of treatment, including: equalization, chemical
precipitation, biological, filtration, and reverse osmosis. During the
engineering site visit, EPA obtained information on:
the facility and its operations;
the wastes accepted for treatment and the facility's
acceptance criteria;
the raw wastewater generated and its sources;
the wastewater treatment on site;
the location of potential sampling points; and
the site-specific sampling needs, issues of access, and
required sampling safety equipment.
EPA conducted week-long sampling efforts at six landfills.
Selection of these facilities was based on the analysis of the
information collected during the engineering site visits.
EPA then prepared a detailed sampling plan for each sampling
episode. Wastewater samples were collected at influent, intermediate,
and effluent sample points throughout the entire on-site wastewater
treatment system. Sampling at 5 of the facilities consisted of 24-hour
composite samples for 5 consecutive days. For the sixth facility,
composites were taken of 4 completed batches over 5 days. Grab samples
were collected for oil and grease, and the volatile organic grab
samples were composited in the laboratory prior to analysis. Samples
were then analyzed using EPA's Office of Water approved analytical
methods. EPA sampling assesses the following technologies:
Equalization
Chemical precipitation
Aerobic biological
Anaerobic biological
Carbon adsorption
Multimedia filtration
Reverse osmosis
Air stripping
Steam stripping
Sludge dewatering
Data resulting from the influent samples were used to develop the
list of pollutants of interest (POIs) and raw wastewater
characteristics. The data collected from the influent, intermediate,
and effluent points were used to analyze the effective treatment at the
facilities, develop current discharge concentrations, pollutant
loadings, and the Best Available Treatment (BAT) options for the
Landfills industry. Data collected from the effluent points were used
to calculate long term averages (LTAs) for each of the proposed
regulatory options.
D. Additional Data Sources
In developing the Landfills effluent guidelines, EPA evaluated the
following data sources:
CERCLA Site Discharges to POTWs Treatability Manual;
Fate of Priority Pollutants in Publicly Owned Treatment
Works (50 POTW Study) database;
EPA's National Risk Management Research Laboratory (NRMRL)
treatability database; and
Industry Supplied Data.
These data sources and their uses for the development of the Landfills
effluent guidelines are discussed below.
Data from the ``CERCLA Site Discharges to POTWs Treatability
Manual'' (EPA 540/G-90/005, August 1990) were used to supplement the
groundwater data collected during characterization and week-long
sampling events. The purpose of the study was to:
Identify the variety of compounds and concentration ranges
present in groundwater at CERCLA sites;
Collect data on the treatability of compounds achieved by
various on-site pretreatment systems; and
Evaluate the impact of CERCLA discharges to a receiving
POTW.
A total of eighteen CERCLA facilities were sampled in this study;
however, only facilities which received contaminated groundwater as a
result of landfilling activities were selected to be used in
conjunction with EPA groundwater sampling data. The data from seven
CERCLA facilities were combined with EPA sampling data to help
characterize the Hazardous Landfill Subcategory and to develop both the
current discharge concentrations and pollutant loadings for facilities
in the Hazardous Landfill Subcategory. In addition, data from three
CERCLA facilities which employed carbon adsorption were combined with
EPA sampling data to conduct the pass-through analysis and to evaluate
the performance of carbon adsorption treatment technology.
EPA used the data included in the report entitled ``Fate of
Priority Pollutants in Publicly Owned Treatment Works'' (EPA 440/1-82/
303, September 1982), commonly referred to as the ``50-POTW Study'', in
determining those pollutants that would pass through a POTW. This study
presents data on the performance of 50 representative POTWs which were
operating at or near the efficiency required to meet
[[Page 6435]]
secondary treatment (30 mg/l BOD\5\ and 30 mg/l TSS). The 50-POTW study
data was edited prior to its use in the landfills regulation. The data
editing hierarchal rules were devised to minimize the possibility that
low POTW removals might simply reflect low influent concentrations
instead of being a true measure of treatment effectiveness. The
hierarchial data editing rules for the 50-POTW study were as follows:
(1) Detected pollutants must have at least three pairs (influent/
effluent) of data points to be included, (2) average pollutant influent
levels less than 10 times the pollutant analytical Minimum Level (ML)
were eliminated, and (3) if none of the average pollutant influent
concentrations exceeded 10 times the ML, then the average influent
values less than 20 g/l were eliminated. The remaining
averaged pollutant influent values and the corresponding averaged
effluent values were then used to calculate the average percent removal
for each pollutant when conducting the POTW pass-through analysis for
this industry, which is discussed in detail in the Technical
Development Document.
EPA's National Risk Management Research Laboratory (NRMRL)
developed a treatability data base (formerly called the Risk Reduction
Engineering Laboratory (RREL) data base). This computerized data base
provides information, by pollutant, on removals obtained by various
treatment technologies. The data base provides the user with the
specific data source, and the industry from which the wastewater was
generated. The NRMRL data base was used when conducting the POTW pass-
through analysis by supplementing the treatment information provided in
the 50-POTW study when there was insufficient information on specific
pollutants. For each of the pollutants of interest (POIs) not found in
the 50-POTW data base, data from portions of the NRMRL data base were
obtained. These files were edited so that only treatment technologies
representative of typical POTW secondary treatment operations
(activated sludge, activated sludge with filtration, aerobic lagoons)
were used. The files were further edited to include information
pertaining to domestic or industrial wastewater, unless only other
wastewater data were available. Pilot-scale and full-scale data were
used; bench-scale data were eliminated. Data from papers in peer-
reviewed journals or government reports were used; lesser quality
references were edited out. From the remaining pollutant removal data,
the average percent removal for each pollutant was calculated.
Finally, EPA solicited any data on landfill wastewaters that may be
relevant from the landfills industry. Several facilities supplied EPA
with leachate and groundwater characterization and treatability
studies. The data included in these studies were analyzed and compared
to EPA sampling data collected at the facilities. Analysis of the
industry provided data confirmed the results of several of EPA sampling
episodes.
VII. Development of Subcategorization Approach
For today's proposal, EPA considered whether a single set of
effluent limitations and standards should be established for this
industry, or whether different limitations and standards were
appropriate for subcategories within the industry. In reaching its
preliminary decision that subcategorization is required, EPA considered
various factors. The CWA requires EPA, in developing effluent
limitations, to assess several factors including manufacturing
processes, products, the size and age of site, wastewater use, and
wastewater characteristics. The landfills industry, however, is not
typical of many of the other industries regulated under the CWA because
it does not produce a product. Therefore, EPA developed additional
factors that specifically address the characteristics of landfill
operations. Similarly, several factors typically considered for
subcategorization of manufacturing facilities were not considered
applicable to the landfills industry. The factors considered for
subcategorization are listed below:
Regulatory classification;
Types of wastes received;
Wastewater characteristics;
Facility size;
Ownership;
Facility location;
Economic impacts;
Treatment technologies and costs;
Facility age;
Energy requirements; and
Non-water quality impacts.
A. Selection of Subcategorization Approach
Based on its assessment of the above factors, EPA has preliminarily
determined that it should segment the landfill industry and develop
different effluent limitations and pretreatment standards for
subcategories of the industry. EPA concluded that the most appropriate
basis for subcategorization is by landfill classification under RCRA
for the reasons explained in greater detail below. Subcategorization on
this basis incorporates many of the most relevant differences within
the landfills industry. EPA found the types of waste received at the
landfill and the resulting characteristics of the wastewater most
clearly correlated with the RCRA classification of a landfill.
Additionally, the Agency believes that this subcategorization approach
has the virtue of being the easiest to implement because it follows the
same classification previously established under RCRA and currently in
use (and widely understood) by permit writers and regulated entities.
The Agency believes that any subcategorization at odds with existing
RCRA classification approaches would potentially create unnecessary
confusion to the regulated community. The proposed subcategories are
described below.
Subcategory I: Subtitle D Non-Hazardous Landfills
Subcategory I would apply to wastewater discharges from all
landfills classified as RCRA Subtitle D non-hazardous landfills subject
to either of the criteria established in 40 CFR Parts 257 (Criteria for
Classification of Solid Waste Disposal Facilities and Practices) or 258
(Criteria for Municipal Solid Waste Landfills) as explained above at
Section [IV].
Subcategory II: Subtitle C Hazardous Landfills
Subcategory II would apply to wastewater discharges from a solid
waste disposal facility subject to the criteria in 40 CFR 264 Subpart
N--Standards for Owners and Operators of Hazardous Waste Treatment,
Storage, and Disposal Facilities and 40 CFR 265 Subpart N--Interim
Standards for Owners and Operators of Hazardous Waste Treatment,
Storage, and Disposal Facilities. Hazardous waste landfills are subject
to requirements outlined in 40 CFR Parts 264 and 265 that include the
requirement to maintain a leachate collection and removal systems
during the active life and post-closure period of the landfill as
explained previously at Section [IV].
B. Factors Considered for Basis of Subcategorization
1. Types of Waste Landfilled
The type of solid waste which is deposited in a landfill often has
a direct correlation with the characteristics of the leachate produced
by that landfill. EPA believes that the most practical method of
distinguishing the type of waste deposited in a landfill is achieved by
utilizing the RCRA classification of
[[Page 6436]]
landfills that distinguishes between hazardous or non-hazardous waste
landfills.
There are also a number of unique landfill cells and monofills
dedicated to accept only one type of non-hazardous solid waste which
may include construction and demolition debris, ash, or sludge. The
Agency is not proposing to further subcategorize Subtitle D landfill
facilities according to the specific type of waste received. This
decision is based on two considerations.
The first consideration is based on EPA's evaluation of leachate
characteristics. EPA evaluated leachate characteristics from many
Subtitle D landfills and concluded that raw leachate was not
significantly different among monofills to merit subcategorization.
This is not unexpected, as the waste deposited in municipal landfills
and dedicated monofills is not mutually exclusive. Although dedicated
cells may prohibit disposal of municipal refuse, a municipal waste
landfill may also accept ash, sludge, and construction and demolition
wastes. EPA concluded that there were no pollutants of concern
identified in dedicated monofills which were not already present in
municipal landfills. EPA concluded that the pollutants proposed to be
regulated for the Subtitle D Subcategory will effectively address the
discharges from all types of Subtitle D landfills, including those
accepting only one type of waste.
The second consideration was based on ease of implementation. As
discussed above, there is overlapping waste acceptance criteria, and
distinct effective dates which define the type of landfill.
Additionally, there are many facilities which operate both dedicated
monofills and municipal landfills and which commingle wastewater prior
to treatment. The Agency believes that establishing one subcategory for
all non-hazardous landfills will ease implementation issues and
adequately control discharges from the landfills industry. EPA solicits
comment on the decision not to subcategorize Subtitle D monofills.
2. Wastewater Characteristics
EPA concluded that leachate characteristics from non-hazardous and
hazardous landfills differed significantly in the types of pollutants
detected and the concentrations of those pollutants. As expected, EPA
found that the leachate from hazardous landfills contained a greater
number of contaminants at higher concentrations compared to leachate
from non-hazardous landfills. This supported subcategorization based on
RCRA classification of hazardous and non-hazardous landfills.
3. Facility Size
EPA considered subcategorization of the landfills industry on the
basis of site size. Three parameters were identified as relative
measures of facility size: number of employees, amount of waste
disposed, and wastewater flow. EPA found that landfills of varying
sizes generate similar wastewaters and use similar treatment
technologies. Furthermore, wastewaters from landfills can be treated to
the same level regardless of facility size. EPA determined that the
industry should not be subcategorized based on facility size. EPA does
not propose a de-minimis flow exclusion for this guideline.
4. Ownership
EPA considered subcategorizing the industry by ownership. A
significant number of landfills are owned by state, local, or federal
governments, while many others are commercially or privately owned.
Although there are distinct economic considerations to account for,
there is no distinction in the wastewater characteristics and
wastewater treatment employed at commercial or municipally owned
landfills. EPA determined that the industry should not be
subcategorized based on ownership.
5. Geographic Location
EPA considered subcategorizing the industry by geographic location.
Landfill sites are not limited to any one region of the United States.
Landfills from all sections of the country were represented in EPA's
survey of the industry. Although wastewater generation rates appear to
vary with annual precipitation, which is indirectly related to
geographic location, a direct correlation in leachate characteristics
to geographic location could not be established. Additionally, the data
collected by EPA did not indicate any significant variations in
wastewater treatment technologies employed by facilities in colder
climates versus warmer climates, nor in the discharge water quality.
EPA determined that geographic location is not an appropriate method
for subcategorization.
EPA noted that geographic location may have a differential impact
on the cost of operating a landfill. For example, the cost of
additional land required for the installation of a treatment system or
the tipping fees charged for waste disposal may vary from region to
region. These issues were addressed in the estimated costs and impacts
of the proposal.
6. Economic Characteristics
EPA also considered subcategorizing the industry based on the
economic characteristics of the landfill facilities. If a group of
facilities with common economic characteristics, such as revenue size,
was in a much better or worse financial condition than others, then it
might be appropriate to subcategorize based on economics. However,
analysis of the financial conditions of facilities showed no
significant pattern of variation across possible subcategories.
7. Treatment Technologies and Costs
The Agency did not consider treatment technologies or costs to be a
basis for subcategorization.
8. Age
EPA considered whether age-related changes in leachate
concentrations of pollutants necessitate different discharge limits for
different age classes of landfills. Several considerations lead to the
conclusion that age-related limits are not appropriate.
First, a facility's wastewater treatment system typically receives
and commingles leachate from several landfills or cells of different
ages. The Agency has not observed any facility which has found it
advantageous or necessary to treat age-related leachates separately.
Second, based on responses to the questionnaire, discussions with
landfill operators and historical data, EPA understands that leachate
pollutant concentrations appear to change substantially over the first
two to five years of operation but then change only slowly thereafter.
These two observations imply that treatment systems must be
designed to accommodate the full range of concentrations expected in
influent wastewaters. EPA concluded that the proposed BPT/BAT/PSES/
NSPS/PSNS treatment technologies are successfully able to treat the
variations in landfill wastewaters likely to occur due to age-related
changes.
Finally, EPA has taken into account the ability of treatment
systems to accommodate age-related changes in leachate (influent)
concentrations, as well as short-term fluctuations by proposing
effluent limitations which reflect the variability observed in
monitoring data spanning up to three years. Additionally, age-related
effects on treatment technologies, costs and pollutant loads were
addressed by utilizing data collected from a variety of
[[Page 6437]]
landfills in various stages of age and operation (e.g. closed,
inactive, active).
EPA solicits comment and data on its conclusions regarding the
relationship of wastewater characteristics to the age of the landfill.
9. Energy Requirements
The Agency did not subcategorize by energy requirements because
this is not a significant factor in this industry and is not related to
wastewater characteristics. Energy costs resulting from this regulation
were accounted for in the economic impact assessment for this
regulation.
10. Non-Water Quality Impacts
The Agency evaluated the impacts of this regulation on the
potential for increased generation of solid waste and air pollution.
The non-water quality impacts did not constitute a basis for
subcategorization. The non-water quality impacts and costs of solid
waste disposal is included in the economic analysis and regulatory
impact analysis for this regulation.
VIII. Wastewater Characterization
This section describes the sources of wastewater flows proposed to
be regulated at landfills. This section also characterizes and
describes these wastewater discharge flows.
A. Sources of Landfill Generated Wastewater
Approximately 7.1 billion gallons of in-scope wastewater were
generated at landfill facilities in 1992. EPA has proposed to regulate
the following landfill sources of wastewater: leachate, gas collection
condensate, truck/equipment washwater, drained free liquids, laboratory
wastewaters, and contaminated stormwater. Additional sources of
wastewaters generated by landfills but not proposed to be regulated
under this guideline include contaminated groundwater, non-contaminated
stormwater, and sanitary wastewaters. These wastewaters are described
below.
1. Leachate, as defined in 40 CFR 258.2, is liquid that has passed
through or emerged from solid waste and contains soluble, suspended, or
miscible materials removed from such waste. Over time the potential for
certain pollutants to movement into the wider environment increase. As
water passes through the landfill, it may ``leach'' pollutants from the
disposed waste moving them deeper into the soil. This presents a
potential hazard to public health and the environment through
groundwater contamination and other means. One measure used to prevent
the movement of toxic and hazardous waste constituents from a landfill
is a landfill liner operated in conjunction with a leachate collection
system. Leachate is typically collected from a liner system placed at
the bottom of the landfill. Leachate also may be collected through the
use of slurry walls, trenches or other containment systems. The
leachate generated varies from site to site based on a number of
factors including: the types of waste accepted; operating practices
(including shedding, daily cover and capping); the depth of fill;
compaction of wastes; annual precipitation; and landfill age. Landfill
leachate accounts for over 95 percent of the in-scope wastewaters.
2. Gas Collection Condensate is liquid which has condensed in a gas
collection system during the extraction of gas from the landfill. Gases
such as methane and carbon dioxide are generated due to microbial
activity within the landfill and must be removed to avoid hazardous
conditions. The gases tend to contain high concentrations of water
vapor which is condensed in traps staged throughout the gas collection
network. The gas condensate contains volatile compounds and accounts
for a relatively small percentage of flow from a landfill.
3. Drained Free Liquids are aqueous wastes drained from waste
containers (e.g. drums, trucks) or wastewater resulting from waste
stabilization prior to landfilling. Landfills which accept
containerized waste may generate this type of wastewater. Wastewaters
generated from these waste processing activities are collected and
usually combined with other landfill generated wastewaters for
treatment at the wastewater treatment plant. Due to the limited amount
of data submitted to EPA on the characteristics of drained free
liquids, and due to the potentially unique nature of these flows, the
Agency solicits comments and data on including drained free liquids
within the scope of this guideline.
4. Truck/Equipment Washwater is generated during either truck or
equipment washes at landfills. During routine maintenance or repair
operations, trucks and/or equipment used within the landfill (e.g.,
loaders, compactors, or dump trucks) are washed and the resultant
wastewaters are collected for treatment. In addition, it is common
practice for many facilities to wash the wheels, body, and
undercarriage of trucks used to deliver the waste to the open landfill
face upon leaving the landfill. On-site wastewater treatment equipment
and storage tanks are also periodically cleaned.
5. Laboratory-Derived Wastewater is generated from on-site
laboratories which characterize incoming waste streams and monitor on-
site treatment performance.
6. Contaminated Stormwater is runoff that comes in direct contact
with the waste or waste handling and treatment areas. Stormwater which
does not come into contact with the wastes .
7. Non-contaminated Stormwater includes stormwater which flows off
the cap or cover of the landfill and does not come in direct contact
with solid waste. The Agency is not proposing to regulate non-contact
stormwater because non-contact stormwater flows are not considered
process wastewaters and are already subject to existing stormwater
regulations. Non-contaminated storm water discharged through municipal
storm water systems or that discharge directly to waters of the United
States are subject to National Pollutant Discharge Elimination System
(NPDES) storm water permit requirements under 40 CFR 122.26 (b)(14)(v).
8. Contaminated Groundwater is water below the land surface in the
zone of saturation which has been contaminated by landfill leachate.
EPA is also not proposing to include within the scope of regulated
flows groundwater which has been contaminated by a landfill and is
collected and discharged. The reasons for this decision are as follows.
During development of this proposal, EPA considered whether it
should also include contaminated groundwater flows within the scope of
this guideline. Historically, many landfill operations have caused the
contamination of local groundwater, mostly as a result of leakage from
unlined landfill units in operation prior to the minimum technology
standards for landfills established by RCRA Subtitle C and D
regulations. Subsequently, State and Federal action under the
Comprehensive Environmental Response Compensation and Liability Act
(CERCLA) has required facilities to clean up contaminated groundwater.
In many cases this has resulted in the collection, treatment and
discharge of treated groundwater to surface waters. In addition, in the
case of RCRA Subtitle C hazardous waste landfills and Municipal solid
Waste Landfills (MSWLF), applicable regulatory standards require
groundwater monitoring and post-closure care and, in the event of
groundwater contamination, corrective action measures. These
requirements may also result in treatment of contaminated groundwater
by such landfill facilities.
[[Page 6438]]
EPA, however, has not included contaminated groundwater flows
within its assessment for this guideline. Several reasons support EPA's
decision not to include contaminated groundwater within the flows
evaluated for this proposal.
EPA evaluated flows, pollutant concentrations, treatment in place,
and current treatment standards for discharges of contaminated
groundwater from landfills. From this evaluation, EPA concluded that
pollutants in contaminated groundwater flows are often very dilute or
are treated to very low levels prior to discharge. EPA concluded that,
whether as a result of corrective action measures taken pursuant to
RCRA authority or State action to clean up contaminated landfill sites,
landfill discharges of treated contaminated groundwater are being
adequately controlled. Consequently, further regulation under this
proposed rule would be redundant and unnecessary.
EPA is aware that there may be some landfill facilities that
collect and treat both landfill leachate and contaminated groundwater
flows. In the case of such facilities, EPA believes that decisions
regarding the appropriate discharge limits again should be left to the
judgment of the permit writer. As indicated above, contaminated
groundwater may be very dilute or may have characteristics similar in
nature to leachate. In cases where the groundwater is very dilute the
Agency is concerned that contaminated groundwater may be used as a
dilution flow. In these cases, the permit writer should develop BPJ
permit limits based on separate treatment of the flows or develop BPT
limits based on the combined wastestream formula in order to prevent
dilution of the regulated leachate flows. However, in cases where the
groundwater may exhibit characteristics similar to leachate, commingled
treatment is appropriate because it is obviously more cost effective
and environmentally beneficial than separate treatment. EPA recommends
that the permit writer consider the characteristics of the contaminated
groundwater before making a determination if commingling groundwater
and leachate for treatment is appropriate.
B. Wastewater Characterization
The Agency's sampling program for this industry detected over 80
pollutants (conventional, priority and non-conventional) in waste
streams at treatable levels. EPA has characterized landfill generated
wastewater using data obtained in EPA sampling episodes and industry
supplied data obtained through the EPA 308 Questionnaires. As
previously explained, EPA sampled at five hazardous landfills and 13
non-hazardous landfills. EPA analyzed untreated and treated wastewaters
for over 470 pollutants at each landfill, including 233 priority and
nonconventional organic compounds, 69 priority and nonconventional
metals, four conventional pollutants, and 123 toxic and nonconventional
pollutants including pesticides, herbicides, dioxins and furans. EPA
developed a list of pollutants of interest (POIs) for the landfills
industry by eliminating pollutants not considered to be at treatable
levels in raw wastewaters. The list of POIs was carried forward in the
analysis.
EPA asked all facilities receiving EPA Detailed Questionnaires to
provide summary characterization data for their landfill generated
wastewaters. The Agency requested selected facilities to submit
detailed analytical data and Detailed Monitoring Reports (DMRs) on
their wastewaters as part of the Detailed Monitoring Questionnaire.
Additionally, EPA reviewed several other wastewater characterization
data sources for comparison purposes.
1. Raw Wastewater at Subtitle D, Municipal Solid Waste (MSW) Landfills
Wastewater generated at MSW landfills contained a range of
conventional, toxic and nonconventional pollutants. Wastewaters
contained significant concentrations of common nonconventional metals
such as iron, magnesium, manganese and boron. Generally, concentrations
of toxic heavy metals were found at relatively low concentrations. EPA
did not find toxic metals such as arsenic, cadmium, mercury and lead at
treatable levels in any of EPA's sampling episodes at MSW landfills.
Typical organic pollutants found in MSW landfill leachate included
2-butanone (methyl ethyl ketone) and 2-propanone (acetone) which are
common solvents used in household products (such as paints and nail
polish) and common industrial solvents such as 4-methyl-2-pentanone and
1,4-dioxane. Trace concentrations of a few pesticides were detected in
wastewaters from municipal landfills. Additionally, the wastewater was
characterized by high loads of organic acids such as benzoic acid and
hexanoic acid resulting from anaerobic decomposition of solid waste.
EPA identified 34 pollutants of interest for MSW landfills
including: eight conventional/nonconventional pollutants, eight metals,
16 organics/pesticides/herbicides, and two dioxins/furans. Three
hundred sixteen pollutants were never detected in EPA sampling episodes
and approximately 120 pollutants were detected but were not considered
to be at treatable levels. A list of the pollutants and sampling
results may be found in the Technical Development Document.
2. Raw Wastewater at Subtitle D, Non-Municipal Landfills
Certain Subtitle D landfills do not accept municipal household
refuse and do not accept hazardous waste. These unique facilities,
termed ``monofills'' because they accept only one type of waste,
typically accept one of the following types of solid waste: municipal
incinerator ash, wastewater treatment sludge, and construction and
demolition (C&D) wastes.
Because of the unique nature of these monofills, EPA performed an
analysis to determine if significant differences existed in raw
wastewater characteristics from Subtitle D Municipal Solid Waste (MSW)
landfills and these monofill facilities. However, characterization and
treatment data collected as part of EPA's sampling episodes focused
primarily on the more prevalent MSW landfills. To complete this
analysis, additional data on raw wastewaters from monofill facilities
were collected from several sources including prior EPA studies and
industry-supplied data. These data were evaluated to identify any
pollutants found at significant concentrations in monofills which were
not found in MSW landfills.
Based on a review of these data sources, EPA observed that the
pollutants present in raw wastewaters from monofills were not
significantly different from those found in MSW landfills, and, in
fact, only a subset of MSW landfill POIs were found in raw wastewaters
from these monofill facilities. In addition, concentrations of
virtually all pollutants found in ash, sludge, and C&D waste monofills
were significantly lower than those found in raw wastewaters from MSW
landfills. As described in Section [VII] of today's notice, EPA
proposes to establish equivalent effluent limitations for all Subtitle
D non-hazardous landfills.
EPA also examined wastewater at non-hazardous landfill facilities
for the presence of dioxins and furans to determine whether these
analytes should be proposed for regulation. Scientific study has
identified that there are 210 isomers of chlorinated dibenzo-p-dioxins
(CDD) and chlorinated dibenzofurans (CDF). Dioxins and furans are
formed as by-products in
[[Page 6439]]
many industrial operations including petroleum refining, pesticide and
herbicide production, paper bleaching, and production of materials
involving chlorinated compounds. Dioxins and furans are not water-
soluble and are not expected to leach out of non-hazardous landfills in
significant quantities. EPA is primarily concerned with the 2,3,7,8-
substituted congeners, of which 2,3,7,8-TCDD is considered to be the
most toxic and is the only one that is a priority pollutant. Non-
2,3,7,8-substituted congeners are believed to be less toxic in part
because it appears that they are not absorbed by living organisms.
As part of EPA sampling episodes at 13 Non-Hazardous landfills, raw
wastewater samples were collected and analyzed for a total of 17
congeners of dioxins and furans. Additional raw leachate data were
analyzed from ash monofills in previous EPA studies. EPA found low
levels of only three congeners, OCDD, HpCDD, and HxCDD, in raw
wastewaters at several landfills. All observed concentrations of
dioxins/furans in raw, untreated wastewater were well below the
Universal Treatment Standards proposed for FO39 wastes (multi-source
leachate) in 40 CFR 268.1 which establish minimum concentration-based
standards based on an acceptable level of risk. At the concentrations
found in raw landfill wastewaters, dioxins and furans are expected to
partition to the biological sludge as part of the proposed BPT/BAT
treatment technologies. Partitioning of dioxins/furans to the sludge
was included in the evaluation of treatment benefits and water quality
impacts. The most toxic dioxin congener, 2,3,7,8-TCDD, was never
detected in raw wastewater at a Subtitle D Landfill.
Based on this review of all available data, the Agency is not
proposing to establish effluent limitations for dioxins and furans
because the concentrations of the congeners that were detected in raw
untreated leachate were found at very low levels, often approaching
background levels and already below Universal Treatment Standards.
Additionally, the most toxic congener, 2,3,7,8-TCDD, was never detected
in untreated raw leachate. EPA sampling data and calculations conclude
that the concentrations of dioxins and furans present in the wastewater
will not prevent the sludge from being redeposited in a nonhazardous
landfill.
3. Raw Wastewater at Subtitle C Hazardous Landfills
Raw wastewaters from Subtitle C Hazardous landfills were also
characterized through EPA sampling episodes and industry-supplied data
obtained through the EPA 308 Questionnaires. Wastewater generated at
Subtitle C hazardous landfills contained a wide range of conventional,
toxic, and nonconventional pollutants at treatable levels. There was a
significant increase in the number of pollutants found in raw
wastewaters at hazardous facilities compared to non-hazardous
landfills. Pollutants which were common to both untreated nonhazardous
and hazardous wastewaters were generally an order of magnitude higher
in hazardous landfill wastewater. The list of pollutants of interest
for the Subtitle C Hazardous Landfill Subcategory, which includes 80
parameters, reflects the more toxic nature of hazardous landfill
wastewater and the wide range of industrial waste sources.
Pollutants typical of raw leachate from hazardous facilities
included higher levels of arsenic, chromium, copper, nickel and zinc
than found at non-hazardous facilities. However, cadmium, lead and
mercury were not detected at treatable concentrations in the raw
wastewater for any of the hazardous landfills sampled during EPA
sampling episodes.
EPA identified 65 pollutants of interest for Subtitle C hazardous
landfills including: 11 conventional/nonconventional pollutants, 13
metals, 37 organics/pesticides/herbicides, and four dioxins/furans. Two
hundred fifty pollutants were never detected in EPA sampling episodes
and approximately 155 pollutants were detected but were not considered
to be present at treatable levels. A list of the pollutants and
sampling results may be found in the Technical Development Document.
EPA also examined wastewater at hazardous landfill facilities for
the presence of dioxins and furans to determine whether these analytes
should be proposed for regulation. As part of EPA sampling episodes at
two in-scope Subtitle C landfills and two in-scope pre-1980 industrial
landfills, raw leachate samples were collected and analyzed for 17
congeners of dioxins and furans. Again, EPA did not detect the most
toxic dioxin congener, 2,3,7,8-TCDD, at an in-scope hazardous/
industrial landfill. EPA did find low levels of several congeners in
raw wastewaters at several landfills. Low levels of four congeners,
OCDD, OCDF, HpCDD, and HpCDF, were detected in over half of the
landfills sampled. However, all concentrations of dioxins/furans in
raw, untreated wastewater were well below the Universal Treatment
Standards proposed for FO39 wastes (multi-source leachate) in 40 CFR
268.1 which establish minimum concentration-based standards based on an
acceptable level of risk. At the concentrations found in raw landfill
wastewaters, dioxins and furans are expected to partition to the
biological sludge as part of the proposed BPT/BAT/PSES treatment
technologies. Partitioning of dioxins/furans to the sludge was included
in the evaluation of treatment benefits and water quality impacts.
Based on a review of all available data, the Agency is not
proposing to establish effluent limitations for dioxins and furans for
the same reasons it is not proposing limitations and standards for
these pollutants in wastewater at non-hazardous landfills.
C. Wastewater Flow and Discharge
1. Wastewater Flow and Discharge at Subtitle D Non-Hazardous Landfills
Approximately 6.7 billion gallons of in-scope wastewater were
generated at non-hazardous landfills in 1992. As mentioned previously,
flows collected from leachate collection systems are the primary source
of wastewater, accounting for over 95 percent of the in-scope
wastewaters.
Landfill facilities have several options for the discharge of their
wastewaters. EPA estimates that there are 158 Subtitle D Non-hazardous
facilities discharging wastewater directly into a receiving stream or
body of water, accounting for 1.2 billion gallons per year. In
addition, there are 762 facilities discharging wastewater indirectly to
a POTW, accounting for 4.6 billion gallons per year.
Also, there are a number of facilities which use treatment and
disposal practices that result in no discharge of wastewater to surface
waters. The Agency estimates that there are 343 of these ``zero or
alternative discharge'' facilities. Disposal options resulting in no
discharge for landfill generated wastewater include off-site treatment
at another landfill wastewater treatment system or a Centralized Waste
Treatment facility, deep well injection, incineration, evaporation,
land application and recirculation.
The recirculation of leachate is generally believed to encourage
the biological activity occurring in the landfill and accelerate the
stabilization of the waste. The recirculation of landfill leachate is
not prohibited by federal regulations, although many States have
prohibited the practice. EPA estimates that 350 million gallons per
year are recirculated back to Subtitle D non-hazardous landfill units.
[[Page 6440]]
2. Wastewater Flow and Discharge at Subtitle C Hazardous Landfills
Approximately 367 million gallons of in-scope wastewater were
generated at hazardous landfills in 1992. In-scope wastewaters do not
include non-contact stormwater or contaminated groundwater.
Landfill facilities have several options for the discharge of their
wastewaters. EPA's survey of the landfills industry did not identify
any hazardous landfills covered by the proposed guideline which
discharge in-scope wastewaters directly to surface waters. EPA
estimates that there are six facilities discharging wastewater
indirectly to a POTW, accounting for 40 million gallons per year.
The Agency estimates that 141 hazardous landfill facilities utilize
zero or alternative-discharge disposal options. EPA estimates that 103
facilities ship wastewater off-site for treatment, often to a treatment
plant located at another landfill or to a Centralized Waste Treatment
facility. Shipping off-site accounts for eleven million gallons per
year of wastewater. Another 37 facilities utilize underground injection
for disposal of their wastewaters, accounting for 315 million gallons
per year; and one facility solidifies less than 0.1 million gallons per
year of landfill wastewater.
IX. Development of Effluent Limitations Guidelines and Standards
A. Description of Available Technologies
There are a large number of different wastewater treatment systems
in use at landfills. The treatment technologies described below provide
some indication of the range of wastewater treatment systems observed
at landfill wastewater treatment plants. In-operation wastewater
treatment technologies include physical/chemical pollutant removal
systems and biological removal systems. Based on information obtained
from the Detailed Questionnaires and engineering site and sampling
visits described above, EPA concluded that a number of treatment
systems currently in place need to be upgraded to improve effectiveness
and remove additional pollutants.
Among the physical/chemical treatment technologies in use are:
Equalization tanks. Equalization dampens variation in
hydraulic and pollutant loadings, thereby reducing shock loads and
increasing treatment facility performance;
Neutralization. Neutralization dampens pH variation prior
to treatment or discharge;
Coagulation/Flocculation. Coagulation/flocculation
provides additional pollutant removal through aggregation of colloidal
solids;
Gravity Separation. Gravity-assisted separation allows
suspended matter, heavier than water, to become quiescent and settle;
and free oils, lighter than water, to become quiescent and float;
Emulsion Breaking. The addition of a de-emulsifiers (heat,
acid, metal coagulants, and clays) break down emulsions to produces a
mixture of water and free oil and/or an oily floc;
Chemical Precipitation. The addition of chemicals to
wastewater to convert soluble metal salts to insoluble metal oxides
which are then removed by filtration;
Chemical Oxidation/Reduction. By chemical addition, the
structure of pollutants are changed so as to disinfect, increase
biodegradation and adsorption, or convert pollutants to terminal end
products;
Air/Steam Stripping. Air/Steam stripping involves the
removal of pollutants from wastewater by the transfer of volatile
compounds from the liquid phase to a gas stream;
Multimedia/Sand Filtration. Multimedia/sand filtration
involves a fixed (gravity or pressure) or moving bed of porous media
that traps and removes suspended solids from water passing though the
media;
Ultrafiltration. Extremely fine grade filters are used to
remove organic pollutants from wastewater according to the organic
molecule size;
Reverse Osmosis. Reverse osmosis relies on differences in
dissolved solids concentrations and selective semipermeable membranes
to allow for the concentration of dissolved inorganic pollutants;
Fabric Filters. Fabric filters screen suspended matter by
means of a cloth or paper barrier;
Carbon Adsorption. In this process, wastewater is passed
over a medium of activated carbon which adsorbs certain pollutants; and
Ion Exchange. The use of certain resins in contact with
wastewater removes contaminants of similar charge.
Biological treatment technologies in use are:
Aerobic Systems. Aerobic systems utilize an acclimated
community of aerobic microorganisms to degrade, coagulate, and remove
organic and other contaminants;
Activated Sludge. Activated sludge is a continuous flow,
aerobic biological treatment process which employs suspended-growth
aerobic microorganisms to biodegrade organic contaminants;
Anaerobic Systems. Anaerobic systems involve the
conversion of organic matter in wastewater into methane and carbon
dioxide by anaerobic microorganisms (methanogens);
Facultative Systems. Facultative systems stabilize wastes
by incorporating a combination of aerobic, anaerobic, and facultative
(thriving in either aerobic or anaerobic conditions) microorganisms;
Rotating Biological Contactors. Rotating biological
contactors (RBCs) employ a fixed-film aerobic biological system
adhering to a rigid media mounted on a horizontal, rotating shaft;
Trickling Filters. In this process, wastewater passes over
a structure packed with an inert medium (e.g. rock, wood, plastic)
coated with a biological film capable of absorbing and degrading
organic pollutants;
Sequential Batch Reactors. A sequence of batch operations
in a single reactor containing acclimated microorganisms is used to
degrade organic material. The batch process allows for equalization,
aeration, and clarification in a single tank;
Powdered Activated Carbon Biological Treatment. The
addition of granular activated carbon to biological treatment systems
enhances the removal of certain organic pollutants;
Nitrification Systems. These systems involve nitrifying
bacteria in order to convert ammonia-nitrogen compounds to less toxic,
nitrate-nitrite compounds;
Denitrification Systems. These systems convert nitrate-
nitrite to nitrogen gas under anoxic conditions; and
Wetlands Treatment. These systems employ natural or man-
made wetlands systems which treat wastewater through utilizing natural
processes of sedimentation, adsorption, and organic degradation.
The treatment sequence employed at any particular facility may vary
with the character of the wastewater generated at the landfill. The
optimal treatment system at a facility depends upon many factors
including permit requirements, design considerations, landfill
acceptance criteria, and management practices. Various forms of
equalization and aerobic biological systems were the most widely-found
treatment technology in the landfills industry, including aerated
lagoons, activated sludge systems, and sequential batch reactors.
Biological systems in the landfill industry generally utilized high
retention times to enhance performance by reducing variations in raw
wastewater flow and pollutant loads.
[[Page 6441]]
B. Technology Options Considered for Basis of Regulation
This section explains how EPA selected the effluent limitations and
standards proposed today for the Subtitle C Landfill and Subtitle D
Landfill Subcategories. To determine the technology basis and
performance level for the proposed regulations, EPA developed a
database consisting of daily effluent data collected from the Detailed
Monitoring Questionnaire and EPA's Wastewater Sampling Program. This
database is used to support the BPT, BCT, BAT, NSPS, PSES, and PSNS
effluent limitations and standards.
The effluent limitations and pretreatment standards EPA is
proposing to establish today are based on well-designed, well-operated
systems. Below is a summary of the technology bases for the proposed
effluent limitations and pretreatment standards in each subcategory.
When final guidelines are promulgated, a landfill operator is free to
use any wastewater treatment technology at the facility so long as the
numerical discharge limits are achieved.
1. Best Practicable Control Technology Currently Available (BPT)
a. Introduction. EPA today proposes BPT effluent limitations for
the two discharge subcategories for the Landfills Point Source
Category. The BPT effluent limitations proposed today would control
identified conventional, priority, and non-conventional pollutants when
discharged from landfill facilities. For further discussion on the
basis for the limitations and technologies selected see the Technical
Development Document.
As previously discussed, Section 304(b)(1)(A) of the CWA requires
EPA to identify effluent reductions attainable through the application
of ``best practicable control technology currently available for
classes and categories of point sources.'' The Senate Report for the
1972 amendments to the CWA explained how EPA must establish BPT
effluent reduction levels. Generally, EPA determines BPT effluent
levels based upon the average of the best existing performances by
plants of various sizes, ages, and unit processes within each
industrial category or subcategory. In industrial categories where
present practices are uniformly inadequate, however, EPA may determine
that BPT requires higher levels of control than any currently in place
if the technology to achieve those levels can be practicably applied.
See A Legislative History of the Federal Water Pollution Control Act
Amendments of 1972, U.S. Senate Committee of Public Works, Serial No.
93-1, January 1973, p. 1468.
In addition, CWA Section 304(b)(1)(B) requires a cost reasonable
assessment for BPT limitations. In determining the BPT limits, EPA must
consider the total cost of treatment technologies in relation to the
effluent reduction benefits achieved. This inquiry does not limit EPA's
broad discretion to adopt BPT limitations that are achievable with
available technology unless the required additional reductions are
``wholly out of proportion to the costs of achieving such marginal
level of reduction.'' See Legislative History, op. cit. p. 170.
Moreover, the inquiry does not require the Agency to quantify benefits
in monetary terms. See e.g. American Iron and Steel Institute v. EPA,
526 F. 2d 1027 (3rd Cir., 1975).
In balancing costs against the benefits of effluent reduction, EPA
considers the volume and nature of expected discharges after
application of BPT, the general environmental effects of pollutants,
and the cost and economic impacts of the required level of pollution
control. In developing guidelines, the Act does not require or permit
consideration of water quality problems attributable to particular
point sources, or water quality improvements in particular bodies of
water. Therefore, EPA has not considered these factors in developing
the limitations being proposed today. See Weyerhaeuser Company v.
Costle, 590 F. 2d 1011 (D.C. Cir. 1978).
b. BPT Technology Options Considered for the Non-Hazardous
Landfills Subcategory. In the Agency's engineering assessment of the
best practicable control technology currently available for treatment
of wastewaters from landfills, EPA first considered three technologies
commonly in use by landfills and other industries as options for BPT.
These technology options were chemical precipitation, biological
treatment, and multimedia filtration. EPA removed chemical
precipitation from further consideration as a BPT treatment option for
the following reason. While chemical precipitation is an effective
treatment technology for the removal of metals, non-hazardous landfills
typically have low concentration of metals in treatment system influent
wastewater. Observed metals concentrations were typically not found at
levels which would inhibit biological treatment or that could be
effectively removed by a chemical precipitation unit.
Option I--Biological Treatment. EPA first assessed the
pollutant removal performance of biological treatment. EPA selected
this as Option I due to its effectiveness in removing the large organic
loads commonly associated with leachate. BPT Option I consists of
aerated equalization followed by biological treatment. Various types of
biological treatment such as activated sludge, aerated lagoons, and
anaerobic and aerobic biological towers or fixed film reactors were
included in the calculation of limits for this option. The costing for
Option I was based on the cost of aerated equalization followed by an
extended aeration activated sludge system and clarification, including
sludge dewatering. Approximately half of the direct discharging
municipal solid waste landfills employed some form of biological
treatment, but only 15 percent had a combination of equalization and
biological treatment.
Option II--Biological Treatment and Multimedia Filtration.
The second technology option considered for BPT treatment of non-
hazardous landfill wastewater was aerated equalization and biological
treatment as described in Option I, followed by multimedia filtration.
Approximately 11 percent of the direct discharging municipal facilities
used the technology described in Option II.
EPA proposes to adopt BPT effluent limitations for the Non-
Hazardous Landfills Subcategory based on Option II because of the
proven ability of biological treatment systems in controlling organics,
and because of the effectiveness of multimedia filtration in removing
TSS which may remain after biological treatment. EPA's decision to base
BPT limitations on Option II treatment reflects primarily two factors:
(1) the degree of effluent reductions attainable and (2) the total cost
of the proposed treatment technologies in relation to the effluent
reductions achieved.
No basis could be found for identifying different BPT limitations
based on age, size, process or other engineering factors. Neither the
age nor the size of the landfill facility will directly affect the
treatability of the landfill wastewaters. For the non-hazardous
landfills, the most pertinent factors for establishing the limitations
are costs of treatment and the level of effluent reductions obtainable.
EPA has selected Option II based on the comparison of the two
options in terms of total costs of achieving the effluent reductions,
pounds of pollutant removals, economic impacts, and general
environmental effects of the reduced pollutant discharges. BPT Option
II removed 85,000 pounds more of conventional pollutants than Option
[[Page 6442]]
I with only a moderate, associated cost increase.
Finally, EPA also looked at the costs of all options to determine
the economic impact that this proposal would have on the landfill
industry. EPA's assessment showed that under either option there were
significant economic impacts on only two facilities. Further discussion
on the economic impact analysis can be found in Section XI of today's
notice.
EPA identified 34 pollutants of interest for the Non-Hazardous
Subcategory as explained previously. EPA is proposing to regulate the
following pollutants under BPT, BAT, and NSPS for direct discharging
non-hazardous landfills: BOD 5, TSS, pH, ammonia, alpha
terpineol, benzoic acid, p-cresol, phenol, toluene, and zinc.
c. BPT Technology Options Considered for the Hazardous Landfill
Subcategory. EPA's survey of the hazardous landfills industry
identified no in-scope respondents who discharge directly to surface
water. All of the hazardous landfills within the scope of the proposal
are either indirect or zero/alternative dischargers. EPA consequently
could not evaluate any treatment systems in place at direct discharging
hazardous landfills for establishing BPT effluent limitations.
Therefore, EPA relied on information and data from widely available
treatment technologies in use at hazardous landfill facilities
discharging indirectly and at non-hazardous landfills discharging
directly--so-called ``technology transfer.'' EPA based BPT limits for
hazardous landfills on chemical precipitation to achieve metals
removals and secondary biological treatment to achieve organics
removals.
In this instance, EPA concluded that the technology in place at
some indirect hazardous landfills is appropriate to use as the basis
for regulation of direct dischargers. EPA would expect that the
wastewater characteristics from direct discharge hazardous waste
landfills be similar to the wastewater from indirect discharge
hazardous waste landfills. The technologies in place at indirect
dischargers selected for the basis of regulation included chemical
precipitation for metals removal and secondary biological treatment for
removals of organics. Secondary biological treatment was selected as
the basis for BPT, BAT, and NSPS regulation for non-hazardous
landfills, and EPA believes that secondary biological treatment is also
appropriate for the treatment of hazardous landfill leachate. With the
exception of conventionals such as BOD 5 and TSS, the
treatment systems in place at indirect hazardous facilities achieved
low effluent concentrations as a result of average removals of 88 to 98
percent of organic toxic pollutants, and 55 to 80 percent of metal
pollutants. Because of the ability of the POTW to treat conventionals
such as BOD 5 and TSS, biological treatment systems
discharging indirectly are not necessarily operated for optimal control
of these parameters. Therefore, because the performance of biological
treatment systems for conventionals is well documented, EPA transferred
the limits for conventionals from well operated biological treatment
systems in place at non-hazardous landfills.
EPA considered three potential technology options for establishing
BPT effluent limitations for the Hazardous Landfill Subcategory. These
technology options all included aerated equalization, and consisted of
chemical precipitation, biological treatment, and zero or alternative
discharge. EPA evaluated chemical precipitation as a treatment
technology because of metals concentrations typically found in
hazardous landfill leachate and the efficient metals removals achieved
through chemical precipitation. EPA also evaluated biological treatment
as an appropriate technology because of its ability to remove organic
loads present in the leachate. Finally, EPA considered a zero or
alternative discharge option as a potential BPT requirement because a
significant segment of the industry is currently not discharging
wastewaters to surface waters or to POTWs. The zero or alternative
disposal option would require facilities to dispose of their wastewater
in a manner that would not result in wastewater discharge to a surface
water or a POTW.
Methods of achieving zero or alternative discharge currently in use
by hazardous landfills are deep well injection, solidification, and
contract hauling of wastewater to a Centralized Wastes Treatment (CWT)
facility or to a landfill wastewater treatment facility. Thirty-seven
facilities are estimated to inject landfill wastewaters underground on-
site, 103 facilities send their wastewater to a CWT or landfill
treatment system, and one facility solidifies wastewater.
EPA has tentatively determined that it should not propose zero or
alternative discharge requirements because, for the industry as a
whole, zero or alternative discharge options are either not viable or
the cost is wholly disproportionate to the benefits and thus it is not
``practicable.''
One demonstrated alternative disposal option for large wastewater
flows is underground injection. However, this is not considered a
practically available option on a nationwide basis because it is not
allowed in many geographic regions of the country where landfills may
be located.
The second widely used disposal option involves contract hauling
landfill wastewater to a CWT. EPA's survey demonstrated that only
landfills with relatively low flows (under 500 g.p.d.) currently
contract haul their wastewater to a CWT. The costs of contract hauling
are directly proportional to the volume and distance over which the
wastewater must be transported, generally making it excessively costly
to send large wastewater flows to a CWT, particularly if it is not
located nearby. EPA evaluated the cost of requiring all hazardous
landfills to achieve zero or alternative discharge status. For the
purposes of costing, EPA assumed that a facility would have to contract
haul wastewater off-site because it may be impossible to pursue other
zero or alternative discharge options. EPA concluded that the cost of
contract hauling off-site for high flow facilities was unreasonable
high and disproportionate to the removals potentially achieved. In
addition, EPA concluded that the wastewater shipped to a CWT will
typically receive treatment equivalent to that proposed today, and that
zero/alternative discharge requirements would result in additional
costs to discharge without greater removals for hazardous landfill
wastewaters.
Based on the characteristics of hazardous landfill leachate and on
an evaluation of appropriate technology options, the Agency selected
aerated equalization followed by chemical precipitation and biological
treatment as BPT technology for the Hazardous Landfill Subcategory. EPA
relied on data from two facilities employing variations of this
technology to calculate the proposed BPT limits for toxic pollutants.
One facility employed equalization and a chemical precipitation unit
followed by an activated sludge system. The second facility used
equalization tanks followed by a sequential batch reactor which was
able to achieve metals reductions. Both of these systems were indirect
dischargers, as stated above. In the case of BPT regulation for
conventional pollutants, EPA concluded that establishing limits based
on indirect discharging treatment systems was not appropriate because
indirect discharging treatment systems are generally not operated for
optimal control of conventional pollutants which are amenable to
treatment in a POTW. Therefore, in establishing limits
[[Page 6443]]
for conventional pollutants, EPA is proposing to establish BPT
limitations equal to those established for non-hazardous landfills. For
a discussion of the costs and economic impact of the treatment options
considered by the Agency, see Section XI.
2. Best Conventional Pollutant Control Technology (BCT)
a. Introduction. In July 1986, EPA promulgated a methodology for
establishing BCT effluent limitations. EPA evaluates the reasonableness
of BCT candidate technologies--those that are technologically
feasible--by applying a two-part cost test: (1) A POTW test; and (2) an
industry cost-effectiveness test.
EPA first calculates the cost per pound of conventional pollutant
removed by industrial dischargers in upgrading from BPT to a BCT
candidate technology and then compares this cost to the cost per pound
of conventional pollutants removed in upgrading POTWs from secondary
treatment. The upgrade cost to industry must be less than the POTW
benchmark of $0.25 per pound (in 1976 dollars).
In the industry cost-effectiveness test, the ratio of the
incremental BPT to BCT cost divided by the BPT cost for the industry
must be less than 1.29 (i.e., the cost increase must be less than 29
percent).
b. Rationale for Setting BCT Equivalent to BPT. In today's
proposal, EPA is proposing to establish BCT effluent limitations
guidelines equivalent to the BPT guidelines for the conventional
pollutants for both subcategories. In developing BCT limits, EPA
considered whether there are technologies that achieve greater removals
of conventional pollutants than proposed for BPT, and whether those
technologies are cost-reasonable according to the BCT Cost Test. In
each subcategory, EPA identified no technologies that can achieve
greater removals of conventional pollutants than proposed for BPT that
are also cost-reasonable under the BCT Cost Test, and accordingly EPA
proposes BCT effluent limitations equal to the proposed BPT effluent
limitations guidelines.
3. Best Available Technology Economically Achievable (BAT)
a. Introduction. EPA today is proposing BAT effluent limitations
for both subcategories in the Landfills Category based on the same
technologies selected for BPT. The BAT effluent limitations proposed
today would control identified priority and non-conventional pollutants
discharged from facilities.
EPA has not identified any more stringent treatment technology
option which it considered to represent BAT level of control applicable
to facilities in this industry.
b. Rationale for Setting BAT Equivalent to BPT for the Non-
Hazardous Landfill Subcategory. EPA evaluated reverse osmosis
technology as a potential option for establishing BAT effluent limits
more stringent than BPT for the control of toxic pollutants. Reverse
osmosis was selected for evaluation because of its effective control of
a wide variety of toxic pollutants in addition to controlling
conventional and non-conventional parameters.
EPA evaluated BAT treatment options as an increment to the baseline
treatment technology used to develop BPT limits. Therefore, the BAT
Option III consisted of BPT Option II (biological treatment followed by
multimedia filtration) followed by a single-stage reverse osmosis unit.
After an assessment of costs and pollutant reductions associated
with reverse osmosis, EPA has concluded that it should not propose BAT
limits based on more stringent treatment technology than the BPT
technology. EPA concluded that a biological system followed by
multimedia filtration would remove the majority of toxic pollutants,
leaving the single-stage reverse osmosis to treat the very low levels
of pollutants that remained. In the Agency's analysis, BPT Option II
removed 6,800 toxic pounds whereas BAT Option III removed 8,000 toxic
pounds. EPA's economic assessment showed that BAT Option III had
significantly higher annual compliance costs than the other options
evaluated and resulted in six additional facilities experiencing
moderate economic impacts (refer to Section XI). In addition,
establishment of BAT Option III would not result in effluent
limitations significantly more stringent that those established under
BAT Option II, which is currently achieving very low Long-Term Average
(LTA) effluent concentrations. Therefore, the Agency questioned whether
the small additional removal of toxic pounds achieved by BAT Option III
were justified by the large incremental cost for the reverse osmosis
treatment system. It should be noted that reverse osmosis was much more
effective at removing the often high quantities of dissolved metals
such as iron, manganese and aluminum. However, these parameters were
not included in the calculation of toxic pounds due to their use as
treatment chemicals. EPA is requesting comment on whether it should
base BAT limits on reverse osmosis because of the additional removals
obtained. For further discussion of the economic impacts and costs of
this option, see the discussion in Section [XI].
c. Rationale for Setting BAT Equivalent to BPT for the Hazardous
Landfill Subcategory. As stated in the BPT analysis, EPA's survey of
the hazardous landfills industry identified no in-scope respondents
which were classified as direct dischargers. All of the hazardous
landfills in the EPA survey were indirect or zero or alternative
dischargers. Therefore, the Agency based BPT limitations on technology
transfer and treatment systems in place for indirect dischargers. In
EPA's engineering assessment of the possible BAT technology for direct
discharging hazardous facilities, EPA evaluated the same three
potential technology options as those evaluated for BPT for the
Hazardous Landfill Subcategory. These technology options were chemical
precipitation, biological treatment, and zero or alternative discharge
as explained above. EPA has identified no other technologies that would
represent BAT level of control for this industry.
EPA determined that it should establish BAT limits based on the
same technology evaluated for BPT limits. As explained above, zero or
alternative discharge is not an available alternative.
4. New Source Performance Standards (NSPS)
a. Introduction. As previously noted, under Section 306 of the Act,
new industrial direct dischargers must comply with standards which
reflect the greatest degree of effluent reduction achievable through
application of the best available demonstrated control technologies.
Congress envisioned that new treatment systems could meet tighter
controls than existing sources because of the opportunity to
incorporate the most efficient processes and treatment systems into
plant design. Therefore, Congress directed EPA, in establishing NSPS,
to consider the best demonstrated process changes, in-plant controls,
operating methods and end-of-pipe treatment technologies that reduce
pollution to the maximum extent feasible.
b. Rationale for Setting NSPS Equivalent to BPT/BCT/BAT. EPA
proposes New Source Performance Standards (NSPS) that would control the
same conventional, priority, and non-conventional pollutants proposed
for control by the BPT/BCT/BAT effluent limitations guidelines. The
conventional treatment technologies used to control pollutants at
existing
[[Page 6444]]
facilities are fully applicable to new facilities. Furthermore, EPA has
not identified any other technologies or combinations of technologies
that are demonstrated for new sources that are different from those
used to establish BPT/BCT/BAT for existing sources. Therefore, EPA
proposes NSPS limitations that are identical to those proposed in each
subcategory for BPT/BCT/BAT. Again, the Agency is requesting comments
to provide information and data on other treatment systems that may be
pertinent to the development of standards for this industry.
5. Pretreatment Standards for Existing Sources (PSES)
a. Introduction. Section 307(b) of the Act requires EPA to
promulgate pretreatment standards to prevent pass-through of pollutants
from POTWs to waters of the U.S. or to prevent pollutants from
interfering with the operation of POTWs. After a thorough analysis of
indirect discharging landfills in the EPA database, EPA has decided not
to propose PSES for the Non-Hazardous Landfill Subcategory for the
reasons explained in more detail below. However, EPA does propose to
establish PSES for the Hazardous Landfill Subcategory based on aerated
equalization, chemical precipitation and biological treatment
technology.
b. Pass-Through Analysis. Before proposing pretreatment standards,
the Agency examines whether the pollutants discharged by an industry
pass through a POTW or interfere with the POTW operation or sludge
disposal practices. In determining whether pollutants pass through a
POTW, the Agency compares the percentage of a pollutant removed by
POTWs with the percentage of the pollutant removed by discharging
facilities applying BAT. A pollutant is deemed to pass through the POTW
when the average percentage removed nationwide by representative POTWs
(those meeting secondary treatment requirements) is less than the
percentage removed by facilities complying with BAT effluent
limitations guidelines for that pollutant.
This approach to the definition of pass-through satisfies two
competing objectives set by Congress: (1) that wastewater treatment
performance for indirect dischargers be equivalent to that for direct
dischargers and (2) that the treatment capability and performance of
the POTW be recognized and taken into account in regulating the
discharge of pollutants from indirect dischargers. Rather than compare
the mass or concentration of pollutants discharged by the POTW with the
mass or concentration of pollutants discharged by a BAT facility, EPA
compares the percentage of the pollutants removed by the proposed
treatment system with the POTW removal. EPA takes this approach because
a comparison of mass or concentration of pollutants in a POTW effluent
with pollutants in a BAT facility's effluent would not take into
account the mass of pollutants discharged to the POTW from non-
industrial sources nor the dilution of the pollutants in the POTW
effluent to lower concentrations from the addition of large amounts of
non-industrial wastewater.
For past effluent guidelines, a study of 50 representative POTWs
was used for the pass-through analysis. Because the data collected for
evaluating POTW removals included influent levels of pollutants that
were close to the detection limit, the POTW data were edited to
eliminate low influent concentration levels. For analytes that included
a combination of high and low influent concentrations, the data was
edited to eliminate all influent values, and corresponding effluent
values, less than 10 times the minimum level. For analytes where no
influent concentrations were greater than 10 times the minimum level,
all influent values less than five times the minimum level and the
corresponding effluent values were eliminated. For analytes where no
influent concentration was greater than five times the minimum level,
the data was edited to eliminate all influent concentrations, and
corresponding effluent values, less than 20 g/l. These editing
rules were used to allow for the possibility that low POTW removal
simply reflected the low influent levels.
EPA then averaged the remaining influent data and the remaining
effluent data from the 50 POTW database. The percent removals achieved
for each pollutant was determined from these averaged influent and
effluent levels. This percent removal was then compared to the percent
removal for the BAT option treatment technology. Due to the large
number of pollutants applicable for this industry, additional data from
the Risk Reduction Engineering Laboratory (RREL) database was used to
augment the POTW database for the pollutants for which the 50 POTW
Study did not cover. For a more detailed description of the pass-
through analysis, see the Technical Development Document.
c. Rationale for Not Proposing PSES for the Non-Hazardous Landfill
Subcategory. The Agency today is not proposing to establish
pretreatment standards for existing sources (PSES) for the Non-
Hazardous Landfill Subcategory. The Agency decided not to propose PSES
for this subcategory after an assessment of the effect of landfill
leachate on receiving POTWs. EPA looked at three measures of effects on
POTWs: biological inhibition levels; contamination of POTW biosolids;
and pass-through. Only one of these, the pass-through analysis, would
support establishing pretreatment standards, and then only in the case
of a single pollutant, ammonia.
With respect to biological inhibition, EPA found that typical
concentrations of raw leachate were below published biological
inhibition levels. Inhibition levels are concentration ranges of
certain pollutants which may upset or interfere with the operation of a
biological treatment system. In the evaluation of landfill wastewater
data, EPA determined that the majority of pollutants typically found in
raw leachate were at levels comparable to wastewater typically found at
the headworks of a POTW.
Further, EPA also projected that there would not be contamination
problems of POTW biosolids as a result of treating landfill leachate so
as to prevent use or disposal of its sewage sludge. Furthermore, in
EPA's study of the indirect dischargers, EPA found no documented
persistent problems with POTW upsets as a result of wastewater from
non-hazardous facilities. EPA is soliciting information on POTW upsets
or POTW sludge contamination problems from accepting landfill leachate.
Finally, EPA conducted a pass-through analysis on the pollutants
proposed to be regulated under BPT/BAT for non-hazardous landfills to
determine if the Agency should establish pretreatment standards for any
pollutant. (The pass-through analysis is not applicable to conventional
parameters such as BOD5 and TSS.) The results showed that
only one regulated pollutant, ammonia, appeared to ``pass-through'' a
POTW. However, upon further evaluation, the Agency concluded that it
should not propose pretreatment standards for ammonia as explained
below. The Agency is soliciting comments and information on its
decision not to propose pretreatment standards for non-hazardous
landfills. Specifically, EPA would like information on the levels of
ammonia present in landfill wastewaters, and on any problems
experienced by POTWs due to the acceptance of landfill leachate with
high ammonia concentrations.
[[Page 6445]]
The Agency evaluated a number of considerations in addition to the
pass-through analysis to determine the need for ammonia pretreatment
standards. In part, this reflects the unique properties of ammonia and
its effects on receiving streams and of the treatment achieved in a
POTW. As previously explained, the pass-through analysis is based on a
comparison of the performance of representative POTWs achieving
secondary treatment and the performance of direct dischargers meeting
limits achieved by BAT technology. In the case of ammonia, POTWs
generally achieve 60 percent ammonia removal through secondary
treatment. However, many POTWs have installed additional treatment
specifically for the control of ammonia and typically achieve removals
in excess of 95 percent--much higher than the 60 percent removal used
in the pass-through analysis. The treatment systems selected as the
basis for the proposed BPT/BAT limits for direct dischargers achieved
average ammonia removals of 81 percent. Thus, while ammonia would pass
through POTWs as tested by the removals (60 percent) achieved in EPA's
50-POTW study, it does not pass through those POTWs with additional
installed ammonia control technology (95 percent removal).
Consequently, EPA did consider establishing pretreatment standards
for ammonia for indirect dischargers whose POTWs do not have
nitrification or other advanced control of ammonia. However, EPA
tentatively rejected this option as not needed because, as described
below, ammonia is either adequately controlled by local limits or the
ammonia concentrations in leachate typically discharged to POTWs are
within the range of concentrations typically found at the headworks to
a POTW. Nevertheless, EPA will further consider this issue and request
comment on whether to establish ammonia pretreatment standards
equivalent to those proposed for direct dischargers. EPA is requesting
additional data pertinent to this issue from POTWs and indirect
discharging landfills. If it is determined that, based on comments
received by the Agency, EPA should establish pretreatment standards for
ammonia, EPA would propose to establish pretreatment standards for
ammonia equivalent to those proposed today for direct discharging
facilities.
In order to determine the need for ammonia pretreatment standards
for the landfills industry, EPA considered the following factors:
``typical'' ammonia concentrations of raw leachate, ``typical'' ammonia
concentrations at the headworks of a POTW, the ammonia concentrations
currently being discharged to POTWs by landfills, national estimates of
ammonia loads discharged to POTWs and to receiving streams, as well as
the economic costs, of establishing pretreatment standards for ammonia.
As discussed previously, EPA found no documented persistent
problems with POTW upsets as a result of accepting landfill generated
wastewater. EPA is soliciting comment specifically with regard to
problems associated with any ammonia discharges in landfill leachate.
In order to evaluate ammonia wastewater concentrations, EPA focused
primarily on the means, medians, and 99th percentile of the data
collected. For raw wastewater (including all direct and indirect
discharging facilities), EPA found that the median concentration of
ammonia in raw landfill leachate was 82 mg/l, and that the average
concentration was 240 mg/l. Additionally, there were several notable
outliers which contained high levels of ammonia in raw leachate due to
site specific characteristics of the landfill.
In terms of current treatment performance for landfills discharging
to POTWs, 99 percent of the landfill facilities are currently
discharging wastewater which contains less than 90 mg/l of ammonia. Of
the indirect landfills which provided data, one facility was
discharging 1,018 mg/l of ammonia to a 114 MGD POTW which currently has
ammonia control (nitrification) in place. In general, POTWs with
nitrification achieve over 95 percent removal of ammonia. The remainder
of the landfills discharged an average concentration of 37 mg/l of
ammonia to POTWs, with one-half of the facilities discharging less than
32 mg/l. In comparison, typical ammonia concentrations in raw domestic
sewage range from one to 67 mg/l. Therefore, with the exception of the
outlier noted above, the average concentration of ammonia in leachate
discharged to POTWs was within the range of wastewater typically
accepted at the headworks to a POTW, although it should be noted that
the upper ranges of leachate concentrations were higher than the upper
ranges observed in domestic sewage. This evidence supports the
conclusion that, in all but a handfull of cases, ammonia is not passing
through POTWs. In most instances, observed ammonia discharge levels to
POTWs fall within a POTWs treatment capabilities. Therefore, EPA does
not believe that national pretreatment standards are necessary.
Additionally, EPA evaluated total wastewater flows and loads of
ammonia to receiving streams associated with non-hazardous landfill
indirect dischargers. EPA estimated that the non-hazardous landfill
industry discharges 3.2 million pounds per year of ammonia to POTWs,
which results in 1.3 million pounds per year being discharged to
receiving streams, assuming that the POTWs have secondary treatment but
do not have additional treatment for ammonia control. (As noted above,
EPA is aware that many POTWs do have additional ammonia control.) Over
65 percent of the landfills discharge less than 10 pounds per day to
the POTW (3,500 pounds/year), which results in discharging less than
four pounds per day (1,400 pounds/year) to receiving streams, again
assuming secondary treatment only. In light of existing ammonia
control, actual discharges to receiving streams are likely to be even
smaller.
EPA did, however, evaluate the economic costs of options for PSES
for ammonia. EPA's economic assessment of these showed that ammonia
removal options generally achieved removals at very high cost given the
small reduction in quantity discharged. For the control of ammonia
there are two technology options available in the landfill industry.
The first available option is biological treatment. EPA evaluated
PSES Option I equivalent to BPT/BAT Option I, which was equalization
plus biological treatment. This option had a total annualized cost of
$28.2 million (1992 dollars) and had an average cost-effectiveness of
$1,072/lbs-equivalent (1981 dollars). The second technology option
available for the control of ammonia is ammonia stripping with
appropriate air pollution controls. However, this technology is not
demonstrated within the landfills industry, the costs are significantly
higher than biological treatment evaluated as PSES Option I, and there
are no pollutant removals achieved incremental to PSES Option I.
In summary, EPA concludes that landfills typically discharge
wastewater to POTWs containing ammonia concentrations comparable to
that of raw domestic sewage and that the POTWs can adequately treat
this wastewater. Further, POTWs retain the ability to establish local
limits on ammonia where necessary because ammonia discharges are often
a water quality issue. Where such discharges are harmful is dependent
upon localized conditions such as the pH and temperature of the
receiving stream. As a result, in these cases where it is
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necessary to protect water quality, many POTWs have established local
limits to control ammonia.
EPA has analyzed the impact of ammonia discharges from landfills on
receiving streams, and potential environmental benefits achieved
through establishing pretreatment standards for ammonia. Based on its
assessment, EPA concluded that ammonia removals achieved by national
pretreatment standards would provide little, if any improvement in
water quality. Consequently, for all the reasons explained above, EPA
concluded that there are minimal benefits to be achieved through
establishing national pretreatment standards for ammonia.
d. Technology Options Considered for PSES for Hazardous Landfill
Subcategory. EPA proposes to establish pretreatment standards for
existing sources for the Hazardous Landfill Subcategory based on the
same technologies as proposed for BPT, BAT, and NSPS for this
subcategory. These standards would apply to existing facilities in the
Hazardous Subcategory that discharge wastewater to publicly-owned
treatment works (POTWs) and would prevent pass-through of pollutants
and help control sludge contamination. Based on EPA's pass-through
analysis, four of the pollutants of concern that may be discharged by
hazardous landfills would pass through POTWs and are proposed for
regulation. These are ammonia, alpha terpineol, aniline, benzoic acid,
p-cresol, and toluene. Nine of the pollutants proposed to be regulated
under BPT, BAT, and NSPS would not pass through a typical POTW. For a
more detailed analysis of the pass-through, refer to the Technical
Development Document. According to EPA's database, all existing
indirect dischargers already meet this baseline standard; and
therefore, no incremental costs, benefits, or economic impacts would be
realized. As discussed above, the Agency is soliciting comment on the
preliminary decision not to adopt zero or alternative discharge
standards for hazardous landfills.
6. Pretreatment Standards for New Sources (PSNS)
a. Introduction. Section 307 of the Act requires EPA to promulgate
both pretreatment standards for new sources (PSNS) and new source
performance standards (NSPS). New indirect discharging facilities, like
new direct discharging facilities, have the opportunity to incorporate
the best available demonstrated technologies including: process
changes, in-facility controls, and end-of-pipe treatment technologies.
b. Rationale for Setting PSNS Equivalent to PSES for All
Subcategories. In today's rule, EPA proposes to establish pretreatment
standards for new sources equivalent to the PSES standards for all
subcategories. In developing PSNS limits, EPA considered whether there
are technologies that achieve greater removals than proposed for PSES
which would be appropriate for PSNS. In the Hazardous Subcategory, EPA
identified no technology that can achieve greater removals than PSES.
In the Non-Hazardous Subcategory, EPA will not establish PSNS
limitations for the same rationale for not establishing PSES limits. As
discussed above, the Agency is soliciting comment on the preliminary
decision not to adopt zero or alternative discharge standards for new
sources of hazardous landfills.
C. Development of Effluent Limitations
EPA based the proposed effluent limitations and standards in
today's notice on widely-recognized statistical procedures for
calculating long-term averages and variability factors. The following
presents a summary of the statistical methodology used in the
calculation of effluent limitations.
Effluent limitations for each subcategory are based on a
combination of long-term average effluent values and variability
factors that account for variation in day-to-day treatment performance
within a treatment plant. The long-term averages are average effluent
concentrations that have been achieved by well-operated treatment
systems using the processes described in the following section
(Treatment Systems Selected for Basis of Regulation). The variability
factors are values that represent the ratio of a large value that would
be expected to occur only rarely to the long-term average. The purpose
of the variability factor is to allow for normal variation in effluent
concentrations. A facility that designs and operates its treatment
system to achieve a long-term average on a consistent basis should be
able to comply with the daily and monthly limitations in the course of
normal operations.
The variability factors and long-term averages were developed from
a data base composed of individual measurements on treated effluent. A
combination of EPA sampling data and industry supplied data was used.
While EPA sampling data reflects the performance of a system over a
five-day period, industry supplied data (collected through the Detailed
Monitoring Questionnaire) reflects up to three years worth of
monitoring data. EPA used a combination of EPA and industry supplied
data whenever possible in order to better account for the variability
of leachate over time.
Daily maximum limits were calculated as follows. A modified delta-
lognormal distribution was fitted to daily concentration data from each
facility that had enough detected concentration values for parameter
estimation. This is the same distributional model used by EPA in the
final rulemakings for the Organic Chemicals, Plastics and Synthetic
Fibers (OCPSF) and Pesticides Manufacturing categories and the proposed
rulemaking for the Pulp and Paper category. This model provided
estimates of the long-term average (mean) and daily variability
(variance) at a facility. Variability factors, corresponding to the
99th percentile, were then computed for each facility. Data were
combined from the selected facilities in each subcategory by finding
the median of facility long-term averages and the average of facility
variability factors. Finally, the daily maximum limitation for a
subcategory was calculated by multiplying the median long-term mean by
the average variability factor. The monthly maximum limitation was
calculated similarly except that the variability factor corresponding
to the 95th percentile of the distribution of monthly averages was used
instead of the 99th percentile of daily concentration measurements.
The daily variability factor is defined as the ratio of the
estimated 99th percentile of the distribution of daily values divided
by the expected value, or mean, of the distribution. Similarly, the
monthly variability factor is defined as the estimated 95th percentile
of the distribution of 4-day or 20-day averages (depending on the
pollutant parameter) divided by the expected value of the monthly
averages.
The modified delta-lognormal distribution models the data as a
mixture of non-detect observations and measured values. This
distribution was selected because the data for most analytes consisted
of a mixture of measured values and non-detects. The modified delta-
lognormal distribution assumes that all non-detects have a value equal
to the reported detection limit and that the detected values follow a
lognormal distribution.
There were several instances where variability factors could not be
calculated from the landfills data base because all effluent values
were measured at or below the minimum detection level. In these cases,
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variability factors were transferred from biological systems used in
the final rulemaking of the OCPSF guideline.
D. Treatment Systems Selected for Basis of Regulation
1. BPT for Non-Hazardous Landfills
There were 46 in-scope landfill facilities in the EPA data base
that employed various forms of biological treatment considered for BPT.
EPA determined an average of the best of these facilities by applying
the criteria outlined below.
The first criterion used in the selection of the average of the
best facilities was effective treatment of BOD5. EPA
evaluated 25 facilities which provided BOD5 effluent data to
determine treatment performance. Because BPT is based on the
effectiveness of biological treatment, facilities which used additional
forms of treatment for BOD5 (other than biological
treatment) were eliminated. EPA, therefore, removed two sites using
carbon treatment in addition to biological treatment from the list of
candidate BPT facilities. EPA eliminated another facility from
consideration due to the fact that it used two separate treatment
trains in treating its wastewater, one with biological treatment and
the other with chemical precipitation, before commingling the streams
at the effluent sample point. After the elimination of these three
facilities, 22 facilities remained in the EPA non-hazardous landfill
data base.
To ensure that the facilities were operating effective biological
treatment systems, EPA first evaluated influent concentrations of
BOD5 entering the treatment system. Three facilities had
average influent BOD5 concentrations below 55 mg/l, and were
not considered for BPT because the influent concentration was
considered to be too low to evaluate removals across the treatment
system. Seven other facilities did not supply BOD5 influent
data and were eliminated from the BPT list. Two other facilities were
dropped because raw wastewater streams consisted primarily of
stormwater or groundwater which were considered dilution flows.
The next requirement for BPT selection in the Non-Hazardous
Landfill Subcategory was that the biological treatment system at the
facility had to achieve a BOD5 effluent concentration less
than 50 mg/l. Facilities not able to maintain an effluent concentration
below 50 mg/l were not considered to be operating their biological
system effectively. Three of the remaining 10 facilities did not
achieve a BOD5 effluent concentration of less than 50 mg/l,
thus leaving seven facilities in the data base.
The seven facilities which met all of the BPT criteria employed
various types of biological treatment systems including activated
sludge, sequential batch reactors, aerobic and anaerobic biological
towers or fixed film, and aerated ponds or lagoons. Most of the
facilities employed equalization tanks in addition to the biological
treatment while several facilities also included chemical precipitation
and neutralization in their treatment systems. The biological systems
were followed by a clarification or sedimentation stage. All seven
facilities employing well-operated biological treatment systems were
used to calculate the effluent limitations for BOD5. The
treatment system average BOD5 influent concentrations ranged
from 150 mg/l to 7,600 mg/l.
EPA used the data from the seven facilities identified as having
good biological treatment systems to calculate the limits for
additional pollutant parameters, including alpha terpineol, ammonia,
benzoic acid, p-cresol, phenol, toluene and zinc. Because one facility
employed air stripping, EPA did not use its data for determining the
proposed limit for ammonia or toluene. Many of the facilities selected
as BPT did not provide data for all the pollutants identified for
regulation by EPA. In these cases, EPA based the limits on the BPT
facilities for which data was available.
While the BOD5 edits discussed above ensure good
biological treatment and a basic level of TSS removal, treatment
facilities meeting this level may not necessarily be operated for
optimal control of TSS. In order to ensure that the TSS data base for
setting limitations reflects proper control, additional editing
criteria for TSS were established.
Two criteria were used for including TSS performance data. The
primary factor in addition to achieving the BOD5 criteria
cited above was that the facility had to employ technology sufficient
to ensure adequate control of TSS, namely a sand or multimedia filter.
Three of the seven well-operated biological systems used a sand or
multimedia filter as a polishing step for additional control of
suspended solids prior to discharge.
The second factor EPA considered was whether the treatment system
achieved an effluent TSS concentration less than or equal to 100 mg/l.
Treatment facilities meeting these criteria were included among the
average best existing performers for TSS. One of the three facilities
had additional treatment for TSS prior to the filter and was therefore
eliminated from consideration in the determination of the TSS limits.
The remaining two facilities had TSS effluent concentrations well below
100 mg/l and thus EPA concluded that they should be included among the
average, best existing performers for TSS. All of the estimated costs
were based on a facility installing aerated equalization tanks followed
by an activated sludge biological system and a multimedia filter and
included a sludge dewatering system. The cost models are described in
detail in the Technical Development Document.
2. Hazardous Landfills
EPA identified only three in-scope respondents in the Hazardous
Landfill Subcategory, all of which discharged indirectly to POTWs. The
leachate from one of the
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