Revision of Wastewater Treatment Exemptions for Hazardous Waste Mixtures (“Headworks Exemptions”), 57769-57785 [05-19841]

Agencies

• ENVIRONMENTAL PROTECTION AGENCY

[Federal Register Volume 70, Number 191 (Tuesday, October 4, 2005)]
[Rules and Regulations]
[Pages 57769-57785]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 05-19841]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 261

[RCRA-2002-0028; FRL-7980-1]
RIN 2050-AE84


Revision of Wastewater Treatment Exemptions for Hazardous Waste 
Mixtures (``Headworks Exemptions'')

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: In today's action, the Environmental Protection Agency is 
finalizing the addition of benzene and 2-ethoxyethanol to the list of 
solvents whose mixtures with wastewaters are exempted from the 
definition of hazardous waste under the Resource Conservation and 
Recovery Act. The scrubber waters derived-from the combustion of any of 
the exempted solvents also are included in the exemption. In addition, 
the Agency is revising the rule by adding an option to allow generators 
to directly measure solvent chemical levels at the headworks of the 
wastewater treatment system to determine whether the wastewater mixture 
is exempt from the definition of hazardous waste. Finally, the Agency 
is extending the eligibility for the de minimis exemption to other 
listed hazardous wastes (beyond discarded commercial chemical products) 
and to non-manufacturing facilities.

DATES: This final rule is effective on November 3, 2005

ADDRESSES: EPA has established a docket for this action under Docket ID 
No. RCRA-2002-0028. All documents in the docket are listed in the 
EDOCKET index at https://www.epa.gov/edocket. Although listed in the 
index, some information is not publicly available, i.e., CBI or other 
information whose disclosure is restricted by statute. Certain other 
material, such as copyrighted material, is not placed on the Internet 
and will be publicly available only in hard copy form. Publicly 
available docket materials are available either electronically in 
EDOCKET or in hard copy at the RCRA Docket, EPA/DC, EPA West, Room 
B102, 1301 Constitution Ave., NW., Washington, DC. The Public Reading 
Room is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, 
excluding legal holidays. The telephone number for the Public Reading 
Room is (202) 566-1744, and the telephone number for the RCRA Docket is 
(202) 566-0270.

FOR FURTHER INFORMATION CONTACT: Lisa Lauer, Hazardous Waste 
Identification Division, Office of Solid Waste (5304W), Environmental 
Protection Agency, 1200 Pennsylvania Ave., NW., Washington, DC 20460; 
telephone number: 703-308-7418; fax number: 703-308-0514; e-mail 
address: Lauer.Lisa@epa.gov.

SUPPLEMENTARY INFORMATION:

General Information

    Entities potentially affected by this action are generators of 
industrial hazardous waste, and entities that treat, store, transport 
and/or dispose of these wastes. The table below is not intended to be 
exhaustive, but rather provides a guide for readers regarding the types 
of entities likely to be affected by this action.

List of Economic Subsectors Potentially Affected by the Expansion in Scope of the RCRA Hazardous Waste ``Headworks Exemption'' for Industrial Wastewater
                                                                    Treatment Systems
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                     Economic subsector or industry identity
               Item               --------------------------------------------                                Description
                                        SIC code             NAICS code
--------------------------------------------------------------------------------------------------------------------------------------------------------
1................................                 02                      112  Agricultural production--livestock.
2................................                 20                      311  Food & kindred products.
3................................                 22                      313  Textile mill products.
4................................                 24                      321  Lumber & wood products.
5................................                 25                      337  Furniture & fixtures.
6................................                 26                      322  Paper & allied products.
7................................                 28                      325  Chemicals & allied products.
8................................                 29                      324  Petroleum & coal products.
9................................                 30                      326  Rubber & miscellaneous plastics products.
10...............................                 31                      316  Leather & leather products.
11...............................                 32                      327  Stove, clay, glass & concrete products.

[[Page 57770]]


12...............................                 33                      331  Primary metal industries.
13...............................                 34                      332  Fabricated metal products.
14...............................                 35                      333  Industrial machinery & equipment.
15...............................                 36                 334, 335  Electrical & electronic equipment.
16...............................                 37                      336  Transportation equipment.
17...............................                 38               3333, 3345  Instruments & related products.
18...............................                 42                      493  Motor freight transportation & warehousing.
19...............................               4581             48819, 56172  Airports, flying fields, & airport terminal services.
20...............................               4789                   488999  Transportation services nec.
21...............................                 49                      221  Electric, gas, & sanitary services.
22...............................                 50                      421  Wholesale trade--durable goods.
23...............................                 51                      422  Wholesale trade--nondurable goods.
24...............................               5999                   453998  Miscellaneous retail.
25...............................                721                     8123  Dry-cleaning & industrial laundry services.
26...............................                 73       514, 532, 541, 561  Business services.
27...............................                 80            621, 622, 623  Health services.
28...............................                 87                      712  Engineering & management services.
29...............................               8999                    54162  Miscellaneous services.
30...............................                 91                      921  Executive, legislative & general government.
31...............................                 95                 924, 925  Environmental quality & housing.
32...............................                 97                      928  National security & international affairs.
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Notes:
 (a) SIC=1987 Standard Industrial Classification system (U.S. Department of Commerce's traditional code system last updated in 1987).
 (b) NAICS=1997 North American Industrial Classification System (U.S. Department of Commerce's new code system as of 1997).
 (c) This list is based upon industry codes reported to the USEPA RCRA hazardous waste 1997 ``Biennial Reporting System'' database by F002/F005 aqueous
  spent solvent generators which manage such wastes in wastewater treatment systems, supplemented by industry codes which have USEPA Clean Water Act
  ``Categorical Pretreatment Standards'' for indirect discharge of industrial wastewaters to POTWs (as of July 2002).
 (d) The USEPA Office of Solid Waste matched 1987 2-digit level SIC 
codes to 1997 NAICS codes using the U.S. Census Bureau website: https://www.census.gov/epcd/naics/nsic2ndx.htm#S0. Refer to the Internet 
Web site https://www.census.gov/epcd/www/naicstab.htm for additional 
information and a cross-walk table for the SIC and NAICS codes systems.

    This table lists the types of entities that EPA believes could be 
affected by this action, based on industrial sectors identified in the 
``Economics Background Document'' in support of this rule. A total of 
about 3,266 to 10,446 entities are expected to benefit from the 
revisions to 40 CFR 261.3 in the 32 industrial sectors listed above, 
but primarily in the chemicals and allied products sector (i.e., SIC 
code 28, or NAICS code 325). Other entities not listed in the table 
also could be affected. To determine whether your facility is covered 
by this action, you should examine 40 CFR part 261 carefully in concert 
with the final rules found at the end of this Federal Register 
announcement. If you have questions regarding the applicability of the 
action to a particular entity, consult the person listed in the FOR 
FURTHER INFORMATION CONTACT section.

                            List of Acronyms
------------------------------------------------------------------------
                  Acronym                              Meaning
------------------------------------------------------------------------
ACC.......................................  American Chemistry Council.
CAA.......................................  Clean Air Act.
CERCLA....................................  Comprehensive Environmental
                                             Response, Compensation, and
                                             Liability Act.
CFR.......................................  Code of Federal Regulations.
CWA.......................................  Clean Water Act
EPA.......................................  Environmental Protection
                                             Agency.
FR........................................  Federal Register.
HSWA......................................  Hazardous and Solid Waste
                                             Amendments.
HWIR......................................  Hazardous Waste
                                             Identification Rule.
LDR.......................................  Land Disposal Restrictions.
MACT......................................  Maximum Achievable Control
                                             Technology.
NAICS.....................................  North American Industrial
                                             Classification System.
NPDES.....................................  National Pollutant Discharge
                                             Elimination System.
NSPS......................................  New Source Performance
                                             Standard.
NTTAA.....................................  National Technology Transfer
                                             and Advancement Act.
OMB.......................................  Office of Management and
                                             Budget.
POTW......................................  Publicly Owned Treatment
                                             Works.
ppm.......................................  parts per million.
RCRA......................................  Resource Conservation and
                                             Recovery Act.
RFA.......................................  Regulatory Flexibility Act.
SBREFA....................................  Small Business Regulatory
                                             Enforcement Fairness Act.
SIC.......................................  Standard Industrial
                                             Classification.

[[Page 57771]]


UMRA......................................  Unfunded Mandates Reform
                                             Act.
WAP.......................................  Waste Analysis Plan.
------------------------------------------------------------------------

Outline

    The information in this preamble is organized as follows:

I. Background
    A. What Law Authorizes These Rules?
    B. What Is the History of the Headworks Rule?
    C. When Will the Final Rule Become Effective?
II. Summary of the Proposed Rule
    A. Which Solvents Were Proposed To Be Added to the Headworks 
Exemption?
    B. What Revisions Were Proposed for the Headworks Compliance 
Monitoring Method?
    C. What Scrubber Waters Were Proposed To Be Exempted?
    D. Exempting Leachate Derived-From Solvent Wastes
    E. Exempting Other Types of Leachate
    F. What Expansions to the De Minimis Exemption Were Proposed?
III. Changes From the Proposed Rule
    A. Exemption for Scrubber Waters Derived-From Spent Solvent 
Combustion
    B. Facilities Using the De Minimis Exemption Will Not Be 
Required To List Limits for Appendix VII and LDR Constituents in 
Their Clean Water Act Permits
    C. ``Unscheduled,'' ``Uncontrollable,'' and ``Insignificant,'' 
Will Not Remain in the Regulatory Text of the De Minimis Exemption
IV. Summary of Responses to Major Comments
    A. Addition of Benzene and 2-Ethoxyethanol to the Headworks 
Exemption
    B. Addition of Direct Monitoring as a Headworks Compliance 
Monitoring Method
    1. General Issues
    2. The Informal Headworks Definition
    3. Sampling and Analysis Plan Issues
    4. Allowing Performance-Based Reduction in Sampling Frequency 
and Changing the Current Compliance Standard
    C. The Exemption of Scrubber Waters Derived-From the 
Incineration of Listed Wastes
    D. Expansion of the De Minimis Exemption
    1. General Issues
    2. Clean Water Act Permit Requirement
    3. Inclusion of ``Unscheduled,'' ``Uncontrollable,'' 
``Insignificant,'' and ``Inadvertent'' in the Regulatory Definition 
of De Minimis
    4. Removal of ``Rinsates From Empty Containers'' From the 
Regulatory Definition of De Minimis
    E. The Potential Exemptions of Leachates Derived-From Solvent 
Wastes and Leachates Derived-From Other Types of Hazardous Wastes
V. State Authorization
    A. How Will Today's Regulatory Changes Be Administered and 
Enforced in the States?
VI. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act
    D. Unfunded Mandates Reform Act
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With 
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From 
Environmental Health Risks and Safety Risks
    H. Executive Order 13211: Actions that Significantly Affect 
Energy Supply, Distribution or Use
    I. National Technology Transfer and Advancement Act of 1995
    J. Congressional Review Act

I. Background

A. What Law Authorizes These Rules?

    These rules are promulgated under the authority of Sections 
2002(a), 3001, 3002, 3004 and 3006 of the Solid Waste Disposal Act of 
1970, as amended by the Resource Conservation and Recovery Act of 1976 
(RCRA), 42 U.S.C. 6912(a), 6921, 6922, 6924, 6938.

B. What Is the History of the Headworks Rule?

    The current wastewater treatment exemptions (``headworks rule'') 
under 40 CFR 261.3(a)(2)(iv)(A)-(G) exempt from the mixture rule spent 
solvents, commercial chemical products, lab wastes, and certain 
additional listed wastes which are a minuscule and treatable part of 
the mix in wastewaters. The ``mixture rule'' dictates that a solid 
waste becomes regulated as a hazardous waste if it is mixed with one or 
more listed hazardous waste (40 CFR 261.3(a)(2)(iv)). The rationale for 
these exemptions is the risk to the environment would be negligible 
because wastewater treatment systems are capable of easily and 
effectively handling small volumes of these organic constituents. After 
the promulgation of the original headworks rule (46 FR 56582, November 
17, 1981), the Agency listed four additional solvents (1,1,2-
trichloroethane, benzene, 2-nitropropane, and 2-ethoxyethanol) in the 
F002 and F005 categories (51 FR 6537, February 25, 1986). However, at 
the time, the Agency did not determine whether or not to add these 
solvents to the headworks rule exemptions.
    In August 1999, EPA received a request from the American Chemistry 
Council (ACC, formerly the Chemical Manufacturers Association) to add 
1,1,2-trichloroethane, benzene, 2-nitropropane, and 2-ethoxyethanol to 
the headworks exemption. ACC also asked the Agency to allow direct 
monitoring as an alternative method for determining compliance with the 
headworks rule. Other ACC-requested headworks rule changes included 
allowing those wastes listed in 40 CFR 261.31 and 261.32 to be added to 
the de minimis exemption and expanding the headworks rule to include 
certain landfill leachates. EPA included a request for comment in the 
November 19, 1999, proposed Hazardous Waste Identification Rule (HWIR) 
(64 FR 63382) on these and other ACC-suggested exemptions to the 
mixture and derived-from rules. Many of the changes in the April 8, 
2003, proposed rule (68 FR 17234) are an outgrowth of ACC's suggested 
revisions and the public comments that EPA received in response to the 
discussion of these suggested revisions in the 1999 HWIR proposal.

C. When Will the Final Rule Become Effective?

    These final regulations will become effective November 3, 2005.

II. Summary of the Proposed Rule

A. Which Solvents Were Proposed To Be Added to the Headworks Exemption?

    On April 8, 2003, we proposed to add to the headworks exemption two 
of the four solvents that were listed in 1986 (68 FR 17234). Benzene 
was proposed to be added at the level of 1 part per million (ppm) with 
these conditions: wastewaters containing benzene are managed in aerated 
biological waste management units; and, surface impoundments used prior 
to secondary clarification are lined (40 CFR 261.3(a)(2)(iv)(A)). The 
addition of these contingent management practices was supported by data 
from the groundwater pathway human health risk analysis which 
demonstrated that non-aerated treatment scenarios resulted in exposures 
above the level of concern for all components of the treatment scenario 
and that aerated biological treatment scenarios resulted in exposures 
above the level of concern only when primary clarifier wastewaters were 
managed in an unlined surface impoundment. (See Risk Assessment to 
Support the Wastewater Treatment Exemptions (Headworks Exemptions) 
Proposed Rule, U.S. EPA 2003).
    In addition, we proposed to add 2-ethoxyethanol to the headworks 
exemption at the level of 25 ppm (40 CFR 261.3(a)(2)(iv)(B)). Data from 
the groundwater pathway human health risk analysis supported this 
proposed addition of 2-ethoxyethanol at 25 ppm

[[Page 57772]]

in the headworks as it posed no significant human health risk at this 
level. (See Risk Assessment to Support the Wastewater Treatment 
Exemptions (Headworks Exemptions) Proposed Rule, U.S. EPA 2003).
    The Agency did not take any action to add 2-nitropropane and 1,1,2-
trichloroethane to the exemption due to the lack of available risk 
information and the failures in the groundwater pathway human health 
risk analysis, respectively.

B. What Revisions Were Proposed for the Headworks Compliance Monitoring 
Method?

    The Agency proposed to add an additional approach for facilities to 
demonstrate compliance with 40 CFR 261.3(a)(2)(iv)(A), (B), (F) and (G) 
of the wastewater treatment exemptions. The additional method is an 
option to directly measure solvent chemical levels at the headworks of 
the wastewater treatment system in lieu of performing mass balance 
calculations. Direct monitoring will be an option for those facilities 
subject to Clean Air Act (CAA) regulations that minimize fugitive 
process or wastewater emissions (e.g., MACT standards under 40 CFR part 
61 or 63 or NSPS requirements under 40 CFR part 60). Facilities taking 
advantage of the proposed direct monitoring approach will be required 
to report the entire concentration of the chemical in question if any 
of it was used as a solvent.
    The proposed addition of direct monitoring as a headworks 
compliance monitoring method required the Agency to address a number of 
implementation issues not associated with the mass balance approach. To 
ensure facilities utilizing the direct monitoring method will 
understand where in the wastewater treatment train sampling is to 
occur, the Agency provided guidance describing the headworks location 
in the proposal (67 FR 17242, April 8, 2003). This guidance mirrors the 
language in the 1981 preamble and provides maximum flexibility by 
accommodating the numerous facility configurations present in the 
regulated community.
    The Agency also proposed that facilities taking advantage of the 
direct monitoring approach are to develop a site-specific sampling and 
analysis plan that demonstrates compliance with the weekly average 
standards set for the appropriate solvent(s). The sampling and analysis 
plan must include the monitoring point location, the sampling frequency 
and methodology, and a list of appropriate constituents to be 
monitored. The Agency proposed that facilities file a copy of the 
sampling and analysis plan with the overseeing agency. However, no 
approval of the plan is required prior to the commencement of the 
direct monitoring method; nevertheless, the facility must have 
confirmation of the plan's receipt (e.g., a certified mail return 
receipt or written confirmation of delivery from a commercial delivery 
service) by the overseeing agency prior to implementation of the direct 
monitoring scheme.

C. What Scrubber Waters Were Proposed To Be Exempted?

    The Agency proposed to add those scrubber waters derived-from the 
combustion of spent solvents that are then subsequently sent to a 
facility's wastewater treatment system to the headworks exemption. The 
Agency believes that the scrubber waters derived-from combustion of 
spent solvent wastes will be comparable in expected constituents and 
concentration levels with spent solvent wastewaters.

D. Exempting Leachate Derived-From Solvent Wastes

    The Agency discussed the ACC request to consider adding leachate 
from landfills that accept only F001-F005 spent solvent wastes to the 
headworks exemption. Because we lacked sufficient data concerning the 
variability, the Agency did not propose an exemption but considered the 
discussion of the issue as an Advanced Notice of Proposed Rulemaking.

E. Exempting Other Types of Leachate

    The Agency also discussed and sought comment regarding a possible 
future addition of leachate from captive, on-site hazardous waste 
landfills to the headworks exemption. Again, because EPA lacked 
adequate information to determine if the levels of constituents present 
in the leachate pose an unacceptable risk, it did not propose an 
exemption for non-solvent leachate.

F. What Expansions to the De Minimis Exemption Were Proposed?

    The Agency proposed to broaden the scope of the de minimis 
exemption (40 CFR 261.3(a)(2)(iv)(D)) in two ways: (1) By expanding the 
eligibility for the exemption beyond manufacturing facilities to 
include non-manufacturing sites such as raw material storage terminals 
and hazardous waste facilities; and, (2) by expanding the types of 
waste eligible for the exemption to include the F- and K-listed wastes 
(Sec. Sec.  261.31 and 261.32). To qualify for the newly expanded 
portions of the de minimis exemption, we also proposed that either the 
manufacturing facilities claiming a de minimis loss of F- or K-listed 
wastes or non-manufacturing facilities claiming a de minimis loss of 
waste listed in Sec. Sec.  261.31 through 261.33 would need to have 
limits for the Appendix VII and Land Disposal Restrictions (LDR) 
constituents associated with their wastes included in their Clean Water 
Act (CWA) permits or that the facilities had to have eliminated the 
discharge of wastewater altogether.
    In addition, the Agency proposed that the words ``unscheduled,'' 
``uncontrollable,'' ``inadvertent,'' and ``insignificant'' be added to 
the regulatory definition. The reasoning behind the addition of these 
words was to provide a clearer understanding of what a de minimis 
release is for all the listed wastes.

III. Changes From the Proposed Rule

A. Exemption for Scrubber Waters Derived-From Spent Solvent Combustion

    In the April 8, 2003, notice, EPA proposed to include in the 
exemption under Sec.  261.3(a)(2)(iv)(A) and (B) those scrubber waters 
derived-from the combustion of spent solvents that then are sent to a 
facility's wastewater treatment system. However, specific regulatory 
language for the inclusion of these scrubber waters in the headworks 
exemption was not included in the proposal. Based on the comments 
received, the final rule includes such language.
    As discussed in the preamble of the proposed rule, scrubber waters 
derived-from the combustion of spent solvents previously were not 
considered eligible for the headworks exemption because they are 
derived-from residuals of spent solvents and their release into the 
wastewater treatment system is not incidental (68 FR 17243, April 8, 
2003). However, in the carbamates rule (60 FR 7824-7859, February 9, 
1995), the Agency allowed scrubber waters derived-from the incineration 
of carbamate production wastes to be eligible for the headworks 
exemption because the scrubber waters would be comparable in the 
expected constituents and concentration levels with the already-
exempted wastewaters. Following the rationale in the carbamates rule, 
the Agency decided to propose in the April 8, 2003 notice that scrubber 
waters derived-from spent solvent combustion which are then sent to a 
facility's wastewater treatment system will be eligible for the 
headworks exemption under Sec.  261.3(a)(2)(iv)(A) and (B). Similar to 
the carbamate scrubber waters, the

[[Page 57773]]

Agency believes that the scrubber waters derived-from such combustion 
will be comparable in expected constituents and concentration levels 
with spent solvent wastewaters.
    Regulatory language has been included under Sec.  
261.3(a)(2)(iv)(A) and (B). The Agency notes the requirement that the 
scrubber waters must be solely derived-from the combustion of the 
listed spent solvents remains unchanged from the proposal.

B. Facilities Using the De Minimis Exemption Will Not Be Required To 
List Limits for Appendix VII and LDR Constituents in Their Clean Water 
Act Permits

    The proposed rule contained a new requirement for those facilities 
taking advantage of the expanded de minimis exemption. Under this 
proposed requirement, a manufacturing facility claiming a de minimis 
loss of F- or K-listed wastes or a non-manufacturing facility claiming 
any de minimis loss of waste listed in Sec. Sec.  261.31 through 261.33 
would have needed limits for the Appendix VII and LDR constituents 
associated with its wastes included in its CWA permit.
    However, commenters noted that permit writers usually do not set 
specific permit limits for every constituent that may be present in the 
effluent. In response to this comment, the Agency instead is requiring 
any facility that would like to claim any part of the expanded 
exemption to list all expected Appendix VII and LDR constituents in the 
CWA permit application. Alerting the permit writers of all expected 
Appendix VII and LDR constituents by listing them in the CWA permit 
application will allow the permit writers to ensure that the permit is 
sufficiently protective of human health and the environment. Similarly, 
facilities that discharge to publicly owned treatment works (POTW) must 
disclose every Appendix VII and LDR constituent that may be released to 
the POTW, as this will alert the POTW of any potential chemicals that 
may pass through or interfere with its operation or cause a permit 
violation. This notification to the permit writer or control authority 
must occur before the facility claims the newly expanded portions of 
the de minimis exemption. EPA has promulgated updated regulatory 
language under Sec.  261.3(a)(2)(iv)(D) in response to these comments.

C. ``Unscheduled,'' ``Uncontrollable,'' and ``Insignificant,'' Will Not 
Remain in the Regulatory Text of the De Minimis Exemption

    In the proposed rule, the words ``unscheduled,'' 
``uncontrollable,'' ``insignificant'' and ``inadvertent'' were added to 
the regulatory definition of de minimis (Sec.  261.3(a)(2)(iv)(D)). 
Numerous commenters were opposed to the addition of these four words 
and requested that they be removed from the regulatory text because the 
words would cause confusion to the regulated community and narrow the 
scope of the exemption. The Agency agrees that these descriptors are 
not necessary and is removing the words ``unscheduled,'' 
``uncontrollable,'' and ``insignificant'' from the regulatory text of 
de minimis. However, the word ``inadvertent'' will remain in the 
regulatory language. The purpose for the addition of ``inadvertent'' in 
the regulatory definition of de minimis is to reinforce the concept 
that the losses must not be a result of neglectful or careless facility 
management. Rather, de minimis refers to small losses that occur during 
normal operating procedures at well-maintained facilities. The Agency 
believes that it is imperative that this concept be conveyed due to the 
exemption being expanded to include the F- and K-listed wastes (Sec.  
231.31 and Sec.  231.32), as well as to non-manufacturing facilities. 
Please see Section IV.D.3. for further discussion regarding the 
addition of the word ``inadvertent'' to the regulatory definition.

IV. Summary of Responses to Major Comments

    The Agency summarizes below the responses to the most significant 
comments received in response to the proposal. All comments received by 
the Agency are addressed in the Response to Comments Background 
Document that is available in the docket associated with this 
rulemaking.

A. Addition of Benzene and 2-Ethoxyethanol to the Headworks Exemption

    Many commenters supported the addition of benzene and 2-
ethoxyethanol as proposed stating that their inclusion in the exemption 
will add consistency to the current regulatory scheme. Several 
commenters emphasized that the spent solvents will remain a very small 
and treatable part of the wastewater mixture. In addition, one 
commenter stated that the contingent management practices placed on the 
addition of benzene to the exemption were very reasonable.
    While there was strong support for the inclusion of the two 
solvents, one commenter disagreed with the addition of benzene and 2-
ethoxyethanol to the exemption at the current concentration levels of 1 
ppm and 25 ppm, respectively. The commenter stated that these levels 
are not protective of human health and the environment and that the 
calculated and direct measurement concentrations need to be reduced. In 
addition, the commenter suggested that the current weekly averaging 
period be decreased to daily or to some other shorter-term averaging 
period; however, the commenter did not submit data to support the 
reduction of the calculated and direct measurement concentrations, nor 
was data submitted to support a reduction in the averaging period.
    The Agency disagrees that the concentration limits of 1 ppm and 25 
ppm for benzene and 2-ethoxyethanol, respectively, are not protective. 
The environmentally conservative risk assessment performed on benzene 
demonstrated that the 1 ppm standard is protective when groundwater is 
indirectly exposed to the wastewater treatment sludge and when 
groundwater is directly exposed to wastewaters and sludge from aerated 
treatment trains (after secondary clarification). Scenarios from non-
aerated systems and primary clarifier sludge from the aerated treatment 
scenario did result in some risks of concern. As a result, we are 
requiring that wastewaters containing benzene be managed in an aerated 
biological treatment unit and that surface impoundments used prior to 
secondary clarification be lined to be eligible for the exemption. The 
risk assessment performed on 2-ethoxyethanol demonstrated it does not 
pose a risk of concern for direct air exposure or for indirect and 
direct groundwater exposures at the concentration limit of 25 ppm. (See 
Risk Assessment to Support the Wastewater Treatment Exemptions 
(Headworks Exemptions) Proposed Rule, U.S. EPA 2003). In regards to the 
commenter's statement that the weekly average be reduced (i.e., that 
the compliance standard be changed), decreasing the averaging period 
from weekly to daily or to some other shorter averaging time addresses 
a provision in the current rule not identified specifically in the 
proposal as subject to possible amendment. EPA stated in the proposed 
rule that it would not respond to comments addressing such provisions 
(68 FR 17241, April 8, 2003).
    One commenter supported the addition of benzene but not the 
conditional management practices. The commenter requested that we 
reconsider

[[Page 57774]]

our proposed conditions and allow benzene to be discharged into 
wastewater treatment systems in the same manner that the other solvents 
listed in Sec.  261.3(a)(2)(iv)(A) are allowed. In the commenter's 
opinion, the conditional management practices are too restrictive and 
inflexible for the addition of benzene to the exemption to be of any 
use to facilities.
    EPA disagrees that the exemption for benzene be unrestricted. Due 
to the exemption being based on the concentration level of benzene 
entering the wastewater treatment system and not wastewater and/or 
sludge waste leaving a facility, evaluation of the risks associated 
with benzene at this level required assuming various treatment methods 
and determining the risks from managing effluents from each interim 
point in a given treatment method (for further discussion, please see 
Risk Assessment to Support the Wastewater Treatment Exemptions 
(Headworks Exemptions) Proposed Rule, U.S. EPA 2003). Aerated and non-
aerated biological treatment, the two methods evaluated during the risk 
assessment, are understood by EPA to be the treatment methods used by 
the vast majority of facilities potentially affected by this rule. The 
conditional requirements on benzene are based directly on the results 
of the risk assessment for benzene (see above). If a facility using a 
method other than aerated biological treatment wishes to exempt their 
wastewater, they can apply for a site-specific delisting for their 
wastewater under Sec.  260.22.
    One commenter requested that we include benzene still bottoms in 
the headworks exemption. This commenter argued that there is no 
regulatory relief for facilities recycling benzene in a still since the 
still bottoms must be managed as a hazardous waste (F005). The 
commenter stated that if the facility's wastewater treatment system has 
the capability of treating the impurities that can be found in still 
bottoms, then the facility should be able to benefit from the exemption 
as well.
    EPA did not consider benzene still bottoms or still bottoms 
resulting from the distillation of other F-listed solvents within the 
scope of the proposed headworks rule. Therefore, still bottoms were not 
included in the risk assessment we performed in support of the addition 
of the spent solvents to Sec.  261.3(a)(2)(iv)(A) and (B). Due to 
concerns regarding constituents, such as metals, which can be found in 
still bottoms, EPA does not believe that it is appropriate to include 
benzene still bottoms in the wastewater treatment exemption without 
having performed a risk assessment. EPA notes that if a facility 
recycling benzene wishes to exempt their benzene still bottoms, they 
can apply for a site-specific delisting for their still bottoms under 
Sec.  260.22.

B. Addition of Direct Monitoring as a Headworks Compliance Monitoring 
Method

1. General Issues
    Most commenters supported the addition of direct monitoring as a 
compliance option. Several cited the complexity for some sites to 
perform the mass balance calculations and commended the Agency for 
proposing to allow direct monitoring at the headworks location as an 
alternative compliance option. No commenters opposed the addition of 
direct monitoring, although several commenters did raise a number of 
issues related to direct monitoring. Separate sections discuss 
commenters' issues and the Agency's responses regarding the informal 
definition of headworks, eliminating the requirement to submit the 
sampling and analysis plan, and allowing performance-based reductions 
in sampling frequency.
    In addition to the issues listed above, many commenters expressed 
support for the requirement that a facility wanting to use direct 
monitoring be subject to CAA rules that minimize fugitive emissions. 
One commenter, however, questioned the eligibility status of those 
facilities that have adopted voluntary limits or controls as part of a 
federally enforceable permit. The Agency agrees that those facilities 
having federally enforceable permits that limit fugitive emissions in 
the facility prior to the headworks are eligible for the exemption as 
these federally enforceable permits are equivalent to a facility being 
subjected to CAA regulations that minimize fugitive emissions. 
Therefore, regulatory language explicitly allowing those facilities 
that have adopted limits or controls for fugitive emissions as part of 
a federally enforceable permit has been added in Sec.  
261.3(a)(2)(iv)(A), (B), (F), and (G).
    Another commenter expressed confusion about whether the CAA rule 
had to apply to the entire facility or just to the wastewater treatment 
unit specifically. The purpose of the requirement is to ensure that 
volatilization of solvents are minimized, and thereby preventing 
fugitive emissions from lowering spent solvent concentration levels, 
prior to the monitoring point at the headworks. EPA considered 
volatilization from the wastewater treatment unit after the headworks 
point (such as from the activated sludge unit or primary clarifier) in 
the Agency's risk assessment and did not find volatilization to be an 
unacceptable source of risk as long as the solvent concentrations at 
the headworks did not exceed the specified levels. Because the 
intention of the requirement is to minimize volatilization prior to the 
headworks point and the risk assessment found that volatilization from 
the wastewater treatment unit did not present an unacceptable risk, it 
is not necessary for the receiving wastewater treatment unit itself to 
be subject to CAA regulations. However, EPA stresses that the process 
streams and wastewater streams that lead up to the headworks point must 
be subject to CAA regulations, or an enforceable limit federal 
operating permit, that minimizes fugitive emissions.
    One commenter objected to the requirement that, under the direct 
monitoring alternative, the generator must count the total amount of 
the chemical in the waste stream, even if some portion of it was from a 
non-solvent source. In addition, another commenter stated that only 
allowing the sampling to occur at the headworks location is 
unnecessarily limiting because the chemical not being used for its 
solvent purposes will be included in the measured level. They asserted 
that these requirements are overly conservative and should be modified, 
suggesting that facilities be allowed to reduce the measured 
concentration by the fraction known to be from non-solvent sources and 
that facilities be allowed to sample wastewaters closer to the point of 
generation. The Agency disagrees. The risk assessment performed by the 
Agency demonstrated that the 1 ppm and 25 ppm standards were protective 
for the total amount of the chemicals (benzene and 2-ethoxyethanol, 
respectively) introduced at the headworks. The source of these 
chemicals is irrelevant for the purposes of determining risk. If the 
solvent fraction of the chemical in the waste stream contributed to the 
total chemical concentration in the wastestream which exceeds the 1 ppm 
or 25 ppm threshold, then that constituent is posing an unacceptable 
risk to human health. Therefore, facilities cannot use a hybrid of the 
results from the mass balance and direct monitoring methods to discount 
the non-solvent source from the total measured concentration, nor can 
facilities sample at alternate locations in lieu of sampling at the 
headworks point. The Agency notes that facilities continue to have the 
option of using mass balance.

[[Page 57775]]

    Another issue of concern by a commenter is the possibility of the 
overseeing agency finding a facility to have exceeded the exemption 
levels on the basis of a compliance method different than the one the 
facility chose to use (e.g., the facility using mass balance and the 
agency using sampling). The overseeing agency will not be bound to use 
the same compliance method chosen by the facility; however, the 
procedures utilized by the overseeing agency when investigating a 
potential violation will be comprehensive enough to determine if the 
facility has exceeded the exemption levels before being found in 
violation.
    Lastly, a commenter requested that we clarify our intent with 
regards to allowing facilities to alternate between the two compliance 
methods or to use a combination of the two methods to demonstrate 
compliance. Facilities will have the option to alternate between the 
two methods or to concurrently use both methods and report the result 
of either method. However, as discussed above, facilities cannot use a 
hybrid of the two methods to demonstrate compliance (e.g., apply the 
solvent percentage to measured concentrations to discount the non-
solvent use). EPA encourages facilities to notify the overseeing agency 
via the sampling and analysis plan that alternating between the 
compliance methods may occur. EPA also encourages facilities to provide 
examples of when a facility may switch from one method to the other. 
EPA notes that facilities may switch monitoring methods even if their 
submitted sampling and analysis plan did not discuss examples of when 
such an occurrence would happen.
2. The Informal Headworks Description
    Several commenters supported the Agency's approach of not proposing 
a formal regulatory definition for the term ``headworks,'' but rather 
providing guidance on what it considers to be the ``headworks'' 
location. In the preamble to the proposed rule, EPA stated that for 
purposes of this rule, ``headworks can include a central catch basin 
for industrial wastewaters, a pump station outfall, equalization tank, 
or some other main wastewater collection area that exists in which 
transport of process wastewaters stops and chemical or biological 
treatment begins'' (68 FR 17242). The Agency did solicit comments on 
this non-regulatory description. Supporters for the informal 
description stated that the description of the term ``headworks'' in 
the preamble to the proposal is flexible enough to accommodate a myriad 
of different facilities within the regulated community. In addition, 
commenters agreed that creating a regulatory definition for 
``headworks'' would result in the loss of this flexibility.
    However, one commenter believed that confusion might result from 
EPA's headworks description because it assumes that no pretreatment is 
occurring prior to the wastewaters' arrival at the headworks. The 
commenter explained that pretreatment frequently occurs upstream to the 
headworks location, and typically there is no one central location 
where all wastewaters come together prior to pretreatment. Therefore, 
the headworks location should be the point where the exemption is 
claimed regardless of whether or not pretreatment has occurred. The 
commenter also stated that the definition of headworks should be 
codified; however, as an alternative to incorporating the definition 
into the regulatory code, the commenter suggested that clarification of 
the location be provided in the preamble of the final rule.
    First, EPA disagrees with the commenter's statement that a 
definition of headworks should be codified. The Agency believes that it 
would be difficult to develop a regulatory definition of the term 
``headworks'' that could apply at all or even most facilities given the 
varied nature of facility configurations. The guidance approach to 
identifying the headworks location accommodates a range of facility 
configurations, thereby providing maximum flexibility. However, EPA 
does agree that the in-process pre-treatment of wastewaters prior to 
their arrival at the headworks location occurs and is allowable under 
this provision. Therefore, EPA is modifying its guidance regarding the 
informal description of the term ``headworks'' so that the headworks 
location can now be described as the point at which final combination 
of raw or pre-treated process wastewater streams typically takes place.
3. Sampling and Analysis Plan Issues
    Many supporters of the direct monitoring option commented that it 
was too burdensome to submit the sampling and analysis plan and to 
obtain confirmation of its receipt before direct monitoring can begin. 
One commenter, who misunderstood the proposed requirement, objected to 
explicit approval having to be obtained by the overseeing agency prior 
to starting direct monitoring. However, the Agency is not requiring 
that the facility obtain explicit approval from their overseeing agency 
prior to the start of direct monitoring. The facility simply is 
required to obtain confirmation of receipt (e.g., a certified mail 
return receipt or written confirmation of delivery from a commercial 
delivery service) prior to starting direct monitoring.
    The Agency disagrees that submittal of the sampling and analysis 
plan is overly burdensome. Submittal of the sampling and analysis plan 
will provide notification to the overseeing agency that a change in 
compliance methodology is planned. This notification is a one-time 
event, unless there is a change in the facility's operations that 
causes a change in monitoring that renders the SAP obsolete. The 
majority of the burden in this requirement is the preparation of the 
sampling and analysis plan, and no commenter objected to developing the 
sampling and analysis plan, correctly recognizing that it is the 
foundation for any rigorous monitoring program.
    Several commenters asserted that requiring the facility to submit 
their sampling and analysis plan ran counter to EPA's recently proposed 
RCRA Burden Reduction Initiative (67 FR 2518, Jan. 17, 2002). In 
addition, commenters noted that in 1997, the Agency specifically 
eliminated the requirement that generators managing and treating 
prohibited waste in tanks, containers and containment buildings under 
40 CFR 262.34 submit sampling and analysis plans to its overseeing 
Agency under 268.7(a)(5). These commenters also pointed out that 
neither the chlorinated aliphatics final rule (65 FR 67068) nor the 
paint production proposed rule (66 FR 10060) required facilities to 
submit their sampling and analysis plans to the overseeing agency, 
instead allowing the facilities to keep their plans on-site.
    EPA believes that it is inappropriate to compare the proposed 
chlorinated aliphatics rule \1\ (64 FR 46476; August 25, 1999) and the 
proposed paints rule \2\ to the headworks rule. While it is true that 
the proposed chlorinated aliphatics rule and the proposed paint 
production rule required sampling and analysis plans to be developed 
but not submitted, there are two significant differences between these 
listing rules and the headworks exemption. First, the testing required 
under the two listing rules is on currently non-hazardous waste to 
document that the waste

[[Page 57776]]

should continue to be out of the hazardous waste regulatory system. In 
contrast, the testing required under the headworks rule is on currently 
hazardous waste to determine whether or not it can safely exit the 
hazardous waste regulatory system. The Agency has generally taken a 
different approach for determining whether a waste is hazardous, as 
opposed to demonstrating that hazardous waste in fact is not hazardous. 
Second, direct monitoring is not a requirement to qualify for the 
headworks exemption; it is an option. If the facility determines that 
submitting the sampling and analysis plan is too burdensome, then the 
facility can opt not to use the direct monitoring method to demonstrate 
compliance but can continue to use the mass balance approach.
---------------------------------------------------------------------------

    \1\ The provision in the proposed chlorinated aliphatics rule 
which stated that facilities must develop but do not need to submit 
their sampling and analysis plan was never finalized.
    \2\ The Agency notes that while the paints rule has been 
finalized, no wastestreams were listed. Therefore, any provisions 
involving sampling and analysis plans were not finalized.
---------------------------------------------------------------------------

    EPA also disagrees that submitting the sampling and analysis plan 
is contradictory to the proposed RCRA Burden Reduction Initiative (67 
FR 2518, Jan. 17, 2002) and the removal in 1997 of the LDR requirement 
to submit the facility's sampling and analysis plan. The purpose of the 
proposed burden reduction rule is to eliminate reports that are found 
to be duplicative or not used by state or regional agencies to protect 
human health and the environment. In today's rule, submitting the 
sampling and analysis plan serves as a notification to the overseeing 
agency that the facility will be using direct monitoring to demonstrate 
compliance with the headworks exemption. The sampling and analysis plan 
also will provide important information on key sampling parameters that 
the facility intends to use. EPA notes that the facility has a wide 
latitude to design the sampling and analysis plan, and the facility 
initially will set the conditions with which they intend to comply. As 
the sampling and analysis plan is not duplicative of any other 
requirement and serves as notification to the overseeing agency, EPA 
believes retaining the requirement to submit the sampling and analysis 
plan is reasonable and consistent with the proposed burden reduction 
rule.
    In addition, while it is true that in 1997 EPA removed the 
requirement of submitting waste analysis plans for generators managing 
and treating prohibited waste in tanks, containers and containment 
buildings, the purpose of removing this requirement was to streamline 
the LDR process (60 FR 43678, August 22, 1995). This streamlining was 
in response to the Burden Reduction Initiative set forth in the 
President's report on ``Reinventing Environmental Regulations,'' March 
16, 1995. EPA stated that due to the growth of the LDR program and the 
regulated community's better understanding of the program, it was 
unnecessary to maintain all of the reporting and recordkeeping 
requirements. Thus, certain LDR paperwork requirements were eliminated 
to reduce the regulatory burden (61 FR 2363, January 25, 1996). EPA 
notes several key differences between the headworks rule and the LDR 
Phase IV rule. First, while the headworks exemption is not a new 
exemption, the addition of direct monitoring as a compliance method is 
a new option. Second, submitting the sampling and analysis plan is not 
a requirement to qualify for the exemption; it is a requirement for the 
use of the direct monitoring option. Therefore, EPA is requiring 
submittal of sampling and analysis plans to provide the overseeing 
agency the opportunity to ensure that facilities are utilizing the 
newly instituted compliance method properly.
    Two commenters requested further clarification regarding the 
rejection of the sampling and analysis plan. One commenter stated that 
if a sampling and analysis plan is submitted in good faith, but only 
exhibits minor flaws, then that facility should be able to continue to 
use the direct monitoring method while the minor inadequacies are being 
addressed. The other commenter requested more explanation regarding the 
actions that need to be taken in order for a facility to restart direct 
monitoring if the sampling and analysis plan is rejected.
    The Agency notes that the parameters of the sampling and analysis 
plan must enable the facility to accurately calculate the weekly 
average concentration, and the plan must include the monitoring point 
location, the sampling frequency and methodology, and a list of the 
constituents to be monitored. Therefore, the Agency maintains that if 
the sampling and analysis plan is rejected for major deficiencies 
(e.g., fails to include the above information or does not enable the 
facility to accurately calculate the weekly average) or if the facility 
is found not to be following the plan, then the facility can no longer 
use the direct monitoring option until the bases for rejection are 
corrected. Even if the overseeing agency does reject the sampling and 
analysis plan, the facility continues to have the option to demonstrate 
compliance using the mass balance method, while the facility is 
addressing the sampling and analysis plan issues. The Agency does 
support the continued use of direct monitoring while deficiencies are 
being corrected if the sampling and analysis plan is submitted in good 
faith and the deficiencies are minor. However, it is left to the 
discretion of the overseeing agency to determine the severity of the 
deficiencies and whether or not direct monitoring may continue while 
the facility addresses such minor deficiencies.
    It is the facility's responsibility to determine from the 
overseeing agency the reason for the rejection and the steps that need 
to be taken to rectify the insufficiencies. The overseeing agency will 
determine whether the facility is to resubmit the entire sampling and 
analysis plan or just the amended sections once the facility corrects 
the bases for the rejection. Once the facility has received 
confirmation that the overseeing agency no longer has concerns with the 
amended sections of the plan, the facility may begin using the direct 
monitoring option.
4. Allowing Performance-Based Reduction in Sampling Frequency and 
Changing the Current Compliance Standard
    Several commenters offered detailed suggestions of how the proposed 
site-specific sampling and analysis plan could establish a sampling 
schedule that would allow a reduced sampling frequency once compliance 
with the 1 ppm and 25 ppm thresholds was established. The commenters 
stated that this approach would be analogous to those taken 
historically in RCRA Waste Analysis Plans (WAP) and in CWA NPDES 
permits.
    The Agency is interested in the possibility of allowing a 
facility's sampling and analysis plan to include a provision to reduce 
sampling frequency based on performance as long as the current 
compliance standards under 261.3(a)(2)(iv)(A) and (B) are maintained 
and the facility's provisions for reduced sampling frequency are 
thoroughly discussed in the plan. However, EPA would first need to 
propose the specific requirements of such a provision in order to allow 
for adequate notice and comment.
    In addition, a number of commenters suggested that EPA increase the 
length of the current compliance period in order to reduce the costs 
associated with direct monitoring. The commenters' suggestion to 
increase the averaging period from weekly to monthly (i.e., the 
compliance period) addresses a provision in the current rule not 
specifically identified in the proposal as subject to possible 
amendment. EPA stated in the proposed rule that it would not respond to 
comments addressing such provisions (68 FR 17241, April 8, 2003).

[[Page 57777]]

C. The Exemption of Scrubber Waters Derived-From the Incineration of 
Listed Wastes

    Numerous commenters supported the proposed addition of scrubber 
waters derived-from the incineration of F-listed solvents to the 
headworks exemption. Several supporters stated that the rationales used 
by EPA to advocate the addition of these scrubber waters are both 
accurate and justifiable. However, many commenters were concerned over 
the Agency reinterpreting the current regulatory language and requested 
that the exemption be incorporated into the regulatory text. Even 
though specific regulatory text for this provision was not proposed, we 
expressly stated in the preamble that the ``Agency is proposing that 
scrubber waters derived from the combustion of spent solvents and sent 
to a facility's wastewater treatment system qualify for the exemption 
under 40 CFR 261.3(a)(2)(iv)(A) and (B)'' (68 FR 17243; April 8, 2003). 
Nevertheless, based on the rational set forth in the preamble to the 
proposal, EPA is promulgating regulatory text to implement the proposed 
addition to the headworks exemption.
    Many commenters stated that limiting the exemption to only scrubber 
waters derived-from the incineration of F-listed solvents was too 
narrow in scope and that the exemption as proposed would not be of much 
benefit to the regulated community. For the exemption to be useful, 
commenters requested that the exemption also apply to scrubber waters 
derived-from the incineration of other F-, K-, P-, and U-listed wastes. 
The commenters claimed that the rationales used to exempt the scrubber 
waters derived-from the F-listed solvents and to exempt the de minimis 
quantities of P- and U-listed wastes could be used to support the 
exemption of the scrubber waters derived-from the incineration of other 
listed wastes in the headworks exemption. As an alternative, some 
commenters stated that the other F-, K-, P-, and U-listed wastes in the 
scrubber waters are analogous to the de minimis quantities of the same 
chemicals. Therefore, the rationale used to exempt the release of de 
minimis quantities of these listed wastes can be applied to justify the 
addition of these scrubber waters into the de minimis exemption (Sec.  
261.3(a)(2)(iv)(D)).
    The Agency disagrees that scrubber waters derived-from the 
incineration of other listed wastes should be included in the headworks 
exemption. Scrubber waters derived-from the incineration of F-listed 
solvents are eligible for the exemption because these scrubber waters 
would be comparable in expected constituents and concentration levels 
with the already exempted F-listed solvents (Sec.  261.3(a)(2)(iv)(A) & 
(B)). This rationale cannot be applied universally to the scrubber 
waters derived-from the incineration of the other listed wastes because 
not all of these listed wastes are currently exempted in Sec.  
261.3(a)(2)(iv)(A) & (B). Therefore, if the listed wastes themselves 
are not exempt, then the scrubber waters derived-from their 
incineration cannot be exempt using this rationale.
    The Agency also will not be including scrubber waters derived-from 
the incineration of U-, P-, K- and other F-listed wastes in the de 
minimis exemption (Sec.  261.3(a)(2)(iv)(D)). EPA's proposal discussed 
expanding the de minimis exemption to facilities other than 
manufacturing facilities and discussed expanding the type of wastes 
that could qualify for the exemption. The proposal did not discuss 
expanding the de minimis exemption to systematic discharges of small 
amounts of waste to a wastewater treatment system. Since originally 
adopted in 1981, the de minimis exemption has removed from regulation 
small amounts of listed wastes that are inadvertently and often 
unavoidably lost under normal material handling operations at well-
maintained facilities. The systematic release of scrubber waters into 
the wastewater treatment system advocated by some of the commenters 
would neither be inadvertent or unavoidable as the scrubber water is a 
segregated wastewater stream at its point of generation. Allowing 
systematic releases to come within the de minimis exemption would be a 
fundamental change in how the de minimis exemption operates and 
arguably would require additional notice and comment to adopt.

D. Expansion of the De Minimis Exemption

1. General Issues
    All who commented on the proposed de minimis expansion generally 
supported it, but many commenters raised specific issues. Separate 
sections discuss commenters' issues and the Agency's responses 
regarding the CWA permit requirement, the inclusion of ``unscheduled,'' 
``uncontrollable,'' ``insignificant'' and ``inadvertent'' in the 
regulatory language and the removal of ``rinsates from empty 
container'' from the regulatory language.
    In addition to the issues listed above, one commenter stated that 
they were interpreting the de minimis exemption expansions to include 
facilities that have eliminated the discharge of wastewaters using 
permitted Class I injection wells. The Agency agrees with this 
interpretation. As explained in the preamble of the original headworks 
rule, the exemptions not only apply to wastewaters that are managed in 
wastewater treatment systems whose discharges are subject to regulation 
under Section 402 or 307(b) of the CWA, but also apply to ``those 
facilities (known as ``zero dischargers'') that have eliminated the 
discharge of wastewater as a result of, or by exceeding, NPDES or 
pretreatment program requirements'' (46 FR 56584, November 17, 1981). 
These wastewater management requirements remain unchanged by the 
amendments to the final headworks rule.
    In addition, EPA continues to believe that underground injection 
wells can meet the headworks' definition of zero discharge if the 
injection well is being used for the purposes of complying with a NPDES 
permit, other applicable effluent guideline, or pretreatment program 
requirements. See discussion in Third Third Rule (55 FR 22672, June 1, 
1990). Wastewaters disposed of via injection well usually are not 
considered discharges under the CWA. However, if underground injection 
of wastewaters occurs for reasons other than to comply with a NPDES 
permit, other applicable effluent guideline or pretreatment program 
requirements, then those wastewaters are not eligible for the 
wastewater treatment (headworks) exemptions (in 40 CFR 
261.3(a)(2)(iv)).
2. Clean Water Act Permit Requirement
    The Agency proposed that for manufacturing facilities claiming a de 
minimis loss of F- or K-listed wastes or non-manufacturing facilities 
claiming a de minimis loss of wastes listed in Sec. Sec.  261.31 
through 261.33, the CWA permit must include limits for the Appendix VII 
hazardous constituents and the LDR constituents associated with the 
listed wastes. Many commenters objected to this proposed requirement. 
Several of these commenters argued that it usually is not the permit 
writer's practice to set specific permit limits for every constituent 
that may be present in the facility's effluent. Rather, they argued 
that listing the waste streams or constituents of concern in the CWA 
permit application will provide the permit writer or control authority 
with the necessary information to decide whether or not a specified 
level or method of treatment is necessary in the permit for the various 
constituents.

[[Page 57778]]

    The rationale for requiring a facility's CWA permit to contain 
limits for Appendix VII and LDR constituents associated with the 
specific wastes was due to the de minimis eligibility being expanded to 
include F- and K-listed wastes. At the time of the proposal, the Agency 
wanted to ensure that the releases of F- and K-listed wastes would be 
minimized so that these wastes would not have a significant effect upon 
wastewater treatment systems, the quality of effluent discharges, solid 
wastes generated, occupational safety and health, and human health and 
the environment (67 FR 17244, April 8, 2003). However, the Agency 
recognizes that it usually is not the permit writer's practice to set 
specific permit limits for every constituent that may be present in a 
facility's effluent. For instance, some constituents are controlled 
through the use of limits on conventional pollutants (such as 
biochemical oxygen demand, total suspended solids, or pH), or thro