o BAT limits applicable to direct dischargers are based on empirical studies of the amount and consistency of removal that can be achieved by a well designed and 77 operated plant. These limits are set so that a discharger can be in compliance virtually all the time. Guidelines are generally calculated with a 99% confidence level. o The 1978 Pretreatment rule required the POTW to conduct 12 influent/ effluent samplings each year. The consistent removal rate was defined as the lowest of the 12 removal rates in the sample, under the assumption that the POTW would be removing at least that amount 95% of the time o In response to complaints from indirect dischargers and POTWs that the 1978 removal credit provision was " unworkable," this definition of consistent removal was amended in the 1981 rule to provide that the level of removal on which the credit would be based would be that achieved by a POTW 75% of the time and was measured by averaging the lowest six of 12 POTW removal samplings. o In 1984, in response to regulated dischargers, EPA amended the rule to base the measurement of consistent removal on the average amount removed in all 12 samplings. That is, the amount of removal achieved by a POTW on average ( 50% of the time) would determine the amount of credit an indirect discharger would receive. The court determined that this provision violated the Clean Water Act.   1987: The Agency replaced the 1984 " consistent removal" provision with the original 1981 provision.   1987: Congress amended section 405 to direct EPA to set numeric limits and management practices for toxic pollutants in sludge.   1993: EPA promulgated the first round of sewage sludge regulations ( 40 CFR Part 503), regulating land application, surface disposal and incineration in sewage sludge incinerators as acceptable use and disposal methods, as well identifying disposal in a municipal solid waste landfill compliant with 40 CFR part 258 as an acceptable disposal practice. Two lists of pollutants for which removal credits could be granted were also included in Appendix G of 40 CFR Part 403.   1997: EPA suggested revising the General Pretreatment Regulations ( § 403.7) to make removal credits available for those pollutants the Agency was no longer considering for the sewage sludge rule. This approach involved a case by case removal credit option that would require indirect dischargers or their POTWs to do a risk assessment based on sitespecific factors, and submit it to EPA for approval. There was substantial opposition among some commenters this approach; the Agency decided not to include it when in the 1999 proposed rule.   July 1999. EPA proposed the Pretreatment Streamlining Regulations, which proposed no changes to the § 403.7 requirements regarding pollutants for which removal credits could be made available. However, the preamble did discuss a process that a POTW or industrial user can follow to petition the Agency to establish a Part 503 standard or an amendment to Part 503, Appendix G for a pollutant along with an analysis of the impact of the pollutant on the use or disposal of its sewage sludge.   December 31, 2003: EPA outlined a final action plan ( 68 FR 75531) in response to a 2002 National Research Council ( NRC) report on Biosolids Applied to Land that 78 identified a need to update the scientific basis of Part 503. Fifteen pollutants were identified from a list of 803 pollutants for further evaluation and possible regulation. Twenty five pollutants were identified with sufficient toxicological and exposure data that would not require regulation under Part 503.

What is the status of EPA's review of the existing Part 503 sewage sludge regulations?

The CWA requires EPA to review the sewage sludge regulations every two years to identify additional toxic pollutants in sewage sludge that may warrant regulation under section 405( d). Under the current biennial review cycle, EPA evaluated publicly available information on the toxicity, persistence, concentration, mobility, and potential for exposure of additional toxic pollutants in sewage sludge. In April 2003, EPA published a Federal Register notice soliciting public comment on the preliminary results of the review, which included a comprehensive list of pollutants found in sewage sludge. At that time, EPA outlined the process it used for compiling and analyzing the comprehensive list of pollutants, but did not identify any additional toxic pollutants for possible regulatory action.

Since publishing the preliminary review results, EPA further analyzed the pollutants on the comprehensive list to determine the sufficiency of available data for an exposure and hazard assessment. EPA then conducted a human health and ecological exposure and hazard screening assessment for those chemicals for which the requisite data was found.

Based on the results of the screening analyses, EPA identified the following 15 chemicals for which it is conducting a more refined exposure and risk assessment. Beryllium Carbon disulfide Chloroaniline, 4; p Chloroaniline Diazinon Fluoranthene Manganese ( from drinking water) * Methyl ethyl ketone; 2 Butanone Nitrate ( as Nitrate nitrogen)

Nitrite ( as Nitrate nitrogen) Phenol Pyrene Silver EPA will update the concentration data on these chemicals by conducting a targeted national sewage sludge survey during 2005. The new concentration data and results will serve as a basis for subsequently determining whether to propose amendments to the sewage sludge regulations for any of these chemicals. The Federal Register Notice ( 68 FR 75531, December 31, 2003) includes timeframes for taking action on these pollutants. Once this action is taken, 79 Appendix G of the Pretreatment regulation would be modified to add the additional pollutants. Additional biennial review cycles will occur per section 405( d)( 2)( C) of the CWA.

5. EPA's Response to Comments As noted, several commenters urged EPA to reconsider its decision not to propose to change the existing procedures for making pollutants eligible for removal credits. More specifically, these commenters suggested that EPA further streamline the regulations to make removal credits available for pollutants EPA is no longer considering for the sewage sludge regulations ( 40 CFR 503). EPA notes that certain pollutants that it evaluated and is no longer considering for the sewage sludge regulations are listed in Appendix G, Table II of the rule and are eligible for removal credits. Moreover, as explained above, EPA is at this time evaluating whether to amend the sewage sludge regulation. During any resulting rulemaking, interested parties may submit information and background data to EPA that would support amendments to Appendix G to add additional pollutants for which removal credits will be available.

EPA could develop upper concentrations for the 25 chemicals listed below that did not fail its exposure and hazard screen described above. Acetophenone Azinphos methyl Benzoic acid Biphenyl, 1,1 Butyl benzyl phthalate Chlorobenzene; Phenyl chloride Chlorobenzilate Chlorpyrifos Cresol, o; 2 Methylphenol Dichloroethene, 1, 2 trans Dichloromethane; Methylene chloride Dioxane, 1,4 Endrin Ethyl p nitrophenyl phenylphosphororthioate; EPN; Sanox Hexachlorocyclohexane, alpha Hexachlorocyclohexane, beta Isobutyl alcohol Methyl isobutyl ketone ( MIBK); Methyl 2 pentanone, 4 Naled N Nitrosdiphenylamine Trichlorofluoromethane Trichlorophenoxy propionic acid, 2 2,4,5; Silvex Trichlororphenoxyacetic acid, 2,4,5; 2,4,5 T Trifluralin 80 Xylenes ( mixture)

Of the 40 pollutants for which EPA determined there is sufficient toxicological and exposure data, these 25 had a Hazard Quotient ( HQ) equal to or less than one. The HQ is the ratio of the magnitude of exposure of the receptor organism ( humans, aquatic organism) to the human health or ecological benchmark. The 15 pollutants that did fail the screen ( i. e. HQ > 1) are now being evaluated for possible regulation and are part of the National Sewage Sludge Survey occurring this year. The 25 pollutants have undergone EPA's rigorous exposure and hazard screen which includes a probabilistic model of 14 potential pathways to humans and ecological endpoints. EPA's development of upper protective concentrations for the 25 pollutants could be done by setting the Hazard Quotients ( HQs) at 1 for each chemical and working back to the chemical concentration that does not exceed the HQ of 1. If an HQ exceeds 1, there is a potential for adverse effects to human health or the environment. Once the concentrations were developed they could be added to Table 2 in Appendix G through an amendment to the pretreatment rule. EPA requests comment on whether the addition of any of these 25 chemicals to Appendix G would be helpful to POTWs and IUs in applying for removal credits. [ EPA plans to propose an amendment to Table 2 in Appendix G by ( date to be determined).]

EPA also notes that several commenters identified that Table I in Part 403, Appendix G contains a technical error in footnote 1. The commenters noted that EPA had not included carbon monoxide among the list of pollutants that are eligible for a removal credit if the requirements for total hydrocarbons in Part 503, Subpart E are met. EPA agrees, and has made this correction.

In addition, an industrial user may be considered for receipt of removal credits if it follows the exposure and hazard assessment presented in the FR presenting the Final Agency response to NRC Report on Biosolids dated December 31, 2003 ( 68 FR 75531). EPA is soliciting information developed consistent with the procedures in the NRC Report for further consideration.

With respect to commenters' concerns about the consistent removal determination which was not addressed in the proposal, the history of the regulations and court cases described above would severely limit any consideration of changes to this provision. However, EPA is requesting comment on whether there are any options to amend the consistent removal provision that would be consistent with the restrictions previously established by the court.

Some commenters on the proposal's overflow provisions did not want removal credits to be allowed where there were overflows in the system. Others wanted to base removal credit approval either on consistent removal or compliance with NPDES permits. Based on these conflicting positions among commenters to the proposed rule and the Agency's ongoing policy discussions pertaining to wet weather discharges, EPA has decided to not adopt the proposed rule's overflow revisions except for deleting redundant requirements, but in addition to the existing requirements in 403.7( h) to include a requirement for the POTW to be in compliance with 81 NPDES permit requirements and enforcement orders or decrees affecting impacted overflows.

I. Miscellaneous Changes ( 40 CFR 403.12( g), ( j), ( l), and ( m))

Signatory Requirements for Industrial User Reports and POTW Reports ( 40 CFR 403.12( l) and ( m))

Today's rule revises the signatory requirements for Industrial Users at 40 CFR 403.12( l)( 1)( ii) to adopt more flexible standards for determining who must sign reports on behalf of a corporation. EPA's NPDES regulations include similar requirements for NPDES permits. See 40 CFR 122.22( a)( 1)( ii). Today's amendments make similar changes to the signatory requirements for " duly authorized employees" of POTWs. See 40 CFR 403.12( m) and 122.22( a).

1. What were the rules in place prior to today's rulemaking?

Sections 403.12( l)( 1)( ii) previously limited the circumstances in which a plant manager could sign a pretreatment report as a responsible corporate officer. Prior to today's rule, in order to sign a report on behalf of a company, the manager was required to manage a facility with more than 250 employees or $ 25 million in sales or expenditures.

Section 403.12( i) addresses annual reporting requirements for POTWs. Prior to today's rule, 40 CFR 403.12( m) required these reports to be signed by " a principal executive officer, ranking elected official or other duly authorized employee if such employee is responsible for overall operation of the POTW."'

2. What changes did EPA propose?

EPA proposed to revise the signatory requirements for Industrial Users at 40 CFR 403.12( l)( 1)( ii) to adopt the same language that EPA proposed in 1996 ( 61 FR 65268) and now uses for direct dischargers at 40 CFR 122.22( a)( 1)( ii). On May 15, 2000, EPA finalized revisions to 40 CFR 122.22( a)( 1)( ii) to replace the numeric criteria for designating an appropriate signer with more flexible narrative criteria ( 64 FR 39595). Rather than conditioning signature authority on resource management size, the revised criteria describe the necessary signer in terms of general management authority and responsibilities. The revision would have required the manager to have the authority to make capital investment decisions and assure long term environmental compliance. 82 In addition, EPA also proposed to revise the signatory requirements for POTW reports at 40 CFR 403.12( m) so the requirement would be more consistent with signatory requirements in the current 40 CFR 122.22( a). EPA proposed to allow signature by a duly authorized employee having responsibility for the overall operation of the facility or activity such as the position of POTW Director, Plant Manager, or Pretreatment Program Manager. This authorization could be made in writing by the principal executive officer or ranking elected official, and submitted to the Approval Authority prior to the report being submitted.

3. What changes is EPA finalizing in today's rule?

In today's final rule, EPA adopts the proposed rule's changes. The following modifications to the proposed rule were made:

Duly Authorized Employee: The proposed rule provided examples of which POTW personnel could sign as a " duly authorized employee." EPA was concerned that the specific examples given ( e. g., POTW Director, Plant Manager, or Pretreatment Program Manager) might have unintentionally limited the designation of " duly authorized employee" at a POTW in the case of an employee that did not have the same exact position title as any of the ones listed in the proposal. To avoid any confusion and provide intended flexibility, today's rule adopts the proposal's requirement that the duly authorized employee be " an individual or position having responsibility for the overall operation of the facility", yet simplifies the language by deleting the examples of specific POTW positions from the proposal.

Authorization for Duly Authorized Employee: EPA clarifies in today's rule that the POTW's authorization of a duly authorized employee to sign POTW reports can be submitted to the Approval Authority " together with" the next annual report. The proposal only provided the option of submitting such authorization " prior to" the annual POTW report.

4. Summary of Major Comments and EPA Response The following is a summary of major comments received and EPA's response:

Do individuals previously authorized to sign POTW reports need to comply with the new " duly authorized representative" requirements? Several commenters observed that individuals currently signing POTW reports for their program, who may have been signing such reports for numerous years, would now need to receive Approval Authority approval prior to signing the next report after today's rule becomes effective. The commenter suggested that EPA add a grandfather provision which enables such individuals to continue signing POTW reports without having to comply with the " duly authorized representative" requirements at 40 CFR 403.12( m).

EPA has not adopted the commenter's suggestion. In EPA's view, the new language provides greater flexibility to POTWs than is currently provided by the pretreatment regulations 83 and clarifies any uncertainty about which employees may be " duly authorized" to sign and submit pretreatment reports. If the commenter chooses to continue its practice of delegating a duly authorized representative to sign relevant reports, this authorization, consistent with 40 CFR 403.12( m) " must be made in writing and submitted to the Approval Authority prior to or together with the report being submitted."

EPA notes that the proposed rule made it seem as if the Approval Authority's approval of duly authorized representatives needed to occur prior to the submission of the next report. Because this is inefficient for the POTW, EPA modified the proposed language in 40 CFR 403.12( m), to indicate that the POTW can request such approval either " prior to or together with" the POTW report being submitted. It is EPA's opinion that this change addresses the commenters' concerns about the inefficiency of waiting for approval from the Approval Authority before submitting a report. EPA sees no reason why the POTW's request to use a duly authorized employee signatory not be considered by the Approval Authority at the same time that it receives the POTW's report.

For Industrial User reports, why is EPA no longer requiring the signatory to be a high level person of authority ultimately responsible for the overall management of the business? One commenter disagreed with the change to 40 CFR 403.12( l) observing that the signatory should continue to be a high level person of authority who is ultimately responsible for the overall management of the business. EPA clarifies that today's rule merely provides greater flexibility in the type of " responsible corporate officer" who may sign reports on behalf of an Industrial User. The revised requirements do not significantly alter the type of official designated as signatory. The Industrial User is still given the same level of flexibility as existed prior to today's rule to choose between a responsible corporate officer, a general partner or proprietor, or a duly authorized representative.

Net/ Gross Calculations ( 40 CFR 403.15)

Today's rule corrects an unintended error in the net/ gross procedures for adjusting categorical pretreatment standards to reflect the presence of pollutants in the Industrial User's intake water. The error appeared to make the test for using these procedures unintentionally difficult to meet.

1. What were the rules in place prior to today's rulemaking?

Net/ gross calculations allow pollutants in intake water to be considered when developing technology based limitations. EPA modified 40 CFR 403.15, the section of the pretreatment regulations addressing net/ gross calculations, in 1988 so that this provision would be consistent with the NPDES provision for net/ gross which had been revised earlier. See discussion at 53 FR 40602 40605, October 17, 1988. The NPDES provision ( 40 CFR 122.45 ( g)) is an " or" test regarding application of effluent standards on a net basis versus control systems meeting standards 84 in the absence of pollutants in the intake water. That is, meeting either condition allows consideration of adjustment. However, the actual language EPA used to modify 40 CFR 403.15 in 1988 erroneously used the term " and" instead of " or", thus inadvertently establishing a test in which both conditions would have to be met. As there are no categorical standards which specify application on a net basis, this resulted in an unintended prohibition on the use of the net/ gross provision in the Pretreatment Program.

2. What changes did EPA propose?

EPA proposed to revise the language in section 40 CFR 403.15 to be consistent with the NPDES regulations and with the intent of the 1988 modification. According to the proposal, Categorical Pretreatment Standards could be adjusted on a " net" basis if either the applicable Pretreatment Standards allow for this calculation or the industrial user demonstrates its control system meets those Pretreatment Standards.

3. What changes is EPA finalizing in today's rule?

EPA has adopted the proposed rule change. No modifications were made to the proposal in the final rule.

4. Summary of Major Comments and EPA Response There were no significant comments on this proposed change.

Requirement to Report All Monitoring Data ( 40 CFR 403.12( g)

Today's rule updates a requirement for categorical industrial users ( CIUs) to report all monitoring data to reflect the fact that this provision should similarly apply to non categorical SIUs, since both types of users are required to submit monitoring reports to the Control Authority.

1. What were the rules in place prior to today's rule?

EPA changed 40 CFR 403.12( g) in 1988 ( see 53 FR 40614, October 17, 1988) to require all monitoring by industrial users to be reported. This was done to avoid the situation in which an industrial user that performs extra sampling to select the most favorable monitoring result to report to the Control Authority. At the time of this change, only CIUs were required by the regulations to report on a regular basis, and therefore, this requirement was limited to CIUs. In 1990, 40 CFR 403.12( h) was added to the regulations ( see 55 FR 30131, July 24, 1990), requiring all significant non categorical industrial users to also sample and report. However, at the time this change was made, the regulations at 40 CFR 403.12( g) were not updated to require all SIUs, categorical and non categorical, to report all monitoring results to the Control Authority. 85 2. What changes did EPA propose?

EPA proposed to change the pretreatment regulations to require all SIUs, both categorical and non categorical SIUs, to report all monitoring results for regulated parameters at the point of compliance, obtained using procedures specified in Part 136, to the Control Authority.

3. What changes is EPA finalizing in today's rule?

EPA adopted the proposed rule change to 40 CFR 403.12( g)( 6). No modifications were made to the proposal in the final rule.

4. Summary of Major Comments and EPA Response Should non SIUs be required to report all monitoring results? Two commenters suggested that EPA revise the scope of its provision to include all Industrial Users. While there are likely important reasons to apply this provision to non SIUs on a case by case basis, EPA declines to do so in a requirement affecting all pretreatment programs. First, EPA did not consider such a revision in the proposal, and it would be inappropriate to do so in this action. Second, while it may make sense to require reporting of all monitoring results for SIUs since they are already required to monitor and report to the POTW, non SIUs are not currently required by the pretreatment regulations to monitor or report. Of course, POTWs may require non SIUs to report all monitoring data to POTWs on a case by case basis if local laws allow. Such a decision is a matter of local discretion.

Notification by Industrial Users of Changed Discharge ( 40 CFR 403.12( j))

Today's rule clarifies that when the Industrial User provides notification of a changed discharge it should go to the " Control Authority", or the Control Authority and the POTW, where the POTW does not have an approved pretreatment program.

1. What were the rules in place prior to today's rule?

In 1988, the regulations were changed to add 40 CFR 403.12 ( j) ( 53 FR 40614, October 17, 1988) requiring all industrial users to promptly notify the POTW of any substantial change in volume or character of pollutants in the user's discharge to the POTW. This notification requirement did not include the Control Authority, which, in some cases, is not the POTW.

2. What changes did EPA propose?

EPA proposed to expand the notification requirement in 40 CFR 403.12( j) so that the industrial user must notify the " Control Authority", as opposed to the " POTW", and in cases 86 where the Control Authority and the POTW are different organizations, the industrial user would notify both the Control Authority and the POTW of any substantial change in volume or character of pollutants in the user's discharge to the POTW.

3. What changes is EPA finalizing in today's rule?

EPA has adopted the proposed rule's revision of 40 CFR 403.12( j). No modifications were made to the proposal in the final rule.

4. Summary of Major Comments and EPA Response There were no significant comments on this proposed change.

J. Equivalent Mass Limits for Concentration Limits ( 40 CFR 403.6( c)( 5))

This section of today's final rule addresses the potential use of mass limits for concentration based categorical standards. EPA is finalizing provisions that allow Industrial Users to request and Control Authorities to approve at their discretion the conversion of concentration based categorical limits to equivalent mass based limits that may be used in lieu of the concentration based limits. The final rule includes eligibility requirements that Industrial Users must satisfy in order to qualify for this conversion, including the use of water conservation methods and technologies during the term of the Industrial User's control mechanism. EPA also specifies procedures which must be followed by the Control Authority in calculating and adjusting the equivalent mass limit. After the equivalent mass limits are in effect, the continued use of the limits is conditioned on the Industrial User's compliance with several requirements, including the maintenance or enhancement of existing control technologies, the continuous recording of flow rates, the notification of the Control Authority where production is expected to be substantially changed, and the retention of water conservation measures.

1. What were the rules in place prior to today's rulemaking?

National categorical Pretreatment Standards establish pollutant limitations in different ways for different categories. EPA has established categorical Pretreatment Standards that are: ( 1) concentration based standards that are implemented directly as concentration limits; ( 2) mass limits based on production rates; ( 3) both concentration based and production based limits; and ( 4) mass limits based on a concentration standard multiplied by a facility's process wastewater flow. Section 403.6( d) allows the Control Authority to develop equivalent mass limits for concentration based standards in order to prevent dilution. However, both the mass limit and concentration limit were then enforceable, so the mass limit would not be an alternative limit.

1. What changes did EPA propose? 87 EPA proposed that the pretreatment regulations be revised so that equivalent mass limits may be authorized by the Control Authority in lieu of promulgated concentration based limits for industrial users. The equivalent mass limit would only be available to Industrial Users that had installed control measures at least as effective as the model treatment technologies that serve as the basis for a particular categorical Pretreatment Standard and that are employing water conservation methods and technologies that substantially reduce water use. The Control Authority would be required to document how the mass limits were derived and make this information publicly available.

3. What changes is EPA finalizing in today= s rule?

EPA is finalizing the proposed rule's change to enable Control Authorities to replace a concentration based Categorical Standard with an equivalent mass limit in a control mechanism issued to an Industrial User. To qualify for use of such an equivalent mass limit, the CIU must meet certain eligibility conditions. These conditions require the CIU to demonstrate that it: ( 1) will implement water conservation measures that substantially reduce water use; ( 2) currently uses control measures at least as effective as the model treatment technologies and agrees to maintain the same or more effective control during the period of time an equivalent mass limit is used, and has not used dilution as a substitute for treatment; ( 3) provides monitoring data to establish its average daily flow rate and its baseline long term average production rate; ( 4) does not have daily flow rates, production rates, or pollutant levels that fluctuate to such a degree that mass limits cannot be appropriately established; and ( 5) has consistently complied with the applicable categorical Pretreatment Standards.

The final rule allows a CIU to initiate a request to be given an equivalent limit, although the Control Authority has the discretion to decide whether the use of equivalent mass limits is appropriate. If the Control Authority approves the request, it then calculates the initial equivalent mass limit by multiplying the average daily flow rate of the CIU by the applicable concentrationbased categorical Pretreatment Standard and the appropriate conversion factor. Assuming the limit is correctly derived and incorporated into the CIU's control mechanism, it is enforceable upon issuance of the control mechanism. [ The appropriateness of an equivalent limit must be reevaluated, and the limit recalculated with the reissuance of the CIU's control mechanism in order to incorporate the facility's new average daily flow rate.] During the term of the control mechanism, the Control Authority may determine that it is necessary to revise the mass limit to reflect a significant change in the rate of production.

After the equivalent mass limit has been developed and incorporated into an effective control mechanism, the continued applicability of the equivalent mass limit depends on the Industrial User's continued compliance with certain requirements. To comply with these requirements, the Industrial User must: ( 1) maintain and effectively operate the same or more effective control and treatment technologies that were in place prior to the mass limits conversion; ( 2) continue to record the facility's flow rates through the use of a continuous effluent flow 88 monitoring device; ( 3) continue to record the facility's production rates and notify the Control Authority if the rates vary by more than 20 percent from its baseline production rates.

These limits will be considered to be equivalent Pretreatment Standards. As with any equivalent Standard, in order for the Approval Authority and the public to be able to verify compliance by the CIUs with these equivalent standards, the Control Authority will need to document how the mass limit calculations were derived and make the documents publicly available ( i. e., to the Approval Authority, EPA, the general public or any third party requesting this information). Setting mass limits does not affect the underlying categorical Pretreatment Standard and does not improperly transfer standard setting authority to the Control Authority. If a Control Authority develops an equivalent mass limit, in lieu of the concentration based categorical Standard, the equivalent limit is a Pretreatment Standard as defined in § 403.5( d) unless the mass limit has not been developed correctly. Compliance with a mass based limit may be used to demonstrate compliance with the categorical Standard only to the extent that the massbased equivalent is properly calculated. If mass limitations have not been developed as required, the source must achieve compliance with the concentration limitations published in the categorical standard.

Which categorical industries are potentially affected by this provision? Section 403.6( c)( 5) applies to qualifying indirect dischargers that are currently subject to Pretreatment Standards expressed as concentration limits. Currently, there are 16 categorical Pretreatment Standards that are concentration based, which do not simultaneously offer a mass based option, and are therefore included within the scope of § 403.6( c)( 5). The following categories are including in this list:

  Inorganic Chemicals ( § 415)   Fertilizer Manufacturing ( § 418)   Petroleum Refining ( § 419)   Steam Electric Power Generating ( § 423)   Leather Tanning ( § 425)   Glass Manufacturing ( § 426)   Rubber Manufacturing ( § 428)   Timber Products Processing ( § 429)   Metal Finishing ( § 433)   Centralized Waste Treatment ( § 437)   Pharmaceutical Manufacturing ( § 439)   Transportation Equipment Cleaning ( § 442)   Paving and Roofing Materials ( § 443)   Commercial Hazardous Waste Combustors Subcategory of the Waste Combustors Point Source Category ( § 444)   Carbon Black Manufacturing ( § 458)   Electrical and Electronic Components ( § 469) 89 EPA also notes that within certain industries affected by today's equivalent mass limits provisions, certain pollutants cannot appropriately be expressed by mass. The NPDES regulations of 40 CFR 122.45( f)( 1)( i) identify the following pollutants are in this category: pH, temperature, and radiation.

In finalizing the rule, EPA is making the following changes to the proposed rule:

Discretionary Use of Equivalent Mass Limits: The final rule emphasizes that the decision on whether to convert the CIU's concentration based categorical Pretreatment Standard to an equivalent mass limit rests with the Control Authority. Though the proposed rule intended to make the Control Authority's decision discretionary, there was considerable uncertainty and concern among the commenters regarding how the language ( e. g., "  the Control Authority may convert the limits  ") was being interpreted, especially by Industrial User commenters concerned that they might be compelled to accept mass limits. The final rule clarifies that Industrial Users initiate the process by requesting that their concentration based limits be converted to equivalent mass limits. The final rule language is as follows: "  the Industrial User may request that the Control Authority convert the limits to equivalent mass limits. If the Industrial User requests equivalent mass limits and all of the requirements in paragraph ( 5)( i)( A) thru ( F) below are met, the determination as to whether equivalent mass limits are appropriate is within the discretion of the Control Authority." Industrial User Eligibility Conditions: EPA has added or revised several requirements that the Industrial User must first meet in order to be considered by the Control Authority for use of an equivalent mass limit. Several of these eligibility requirements are also conditions that must be met in order to continue use of mass limits after becoming effective. The final rule includes the following new or rephrased requirements:

( 1) Implementation of Water Conservation: EPA has revised the proposed language requiring the Industrial User to be " employing water conservation methods and technologies that substantially reduce water use" to make it clear that ongoing as well as future water conservation efforts can both qualify for the use of equivalent mass limits. The final rule also requires that the water conservation occur during the initial term of the Industrial User's control mechanism which enforces equivalent mass limits. During subsequent control mechanism terms, the Industrial User must continue to use the methods and technologies by which water conservation was achieved. The revised rule language is as follows: " the Industrial User must demonstrate that it   will employ water conservation methods and technologies that substantially reduce water use during the term of its control mechanism." See § 403.6( c)( 5)( i)( C). The final rule also requires that Industrial Users " continue to employ the water conservation methods and technologies implemented pursuant to paragraph ( 5)( i)( C)." See § 403.6( c)( 5)( iii)( D). 90 ( 2) Use of Effective Control and Treatment Technologies: The proposed rule required " control measures at least as effective as the model treatment technologies that serve as the basis for that particular Standard." The final rule includes a slight revision to this language, even though the principle of requiring the installation and use of effective control measures to meet the applicable Pretreatment Standards for Existing Sources ( PSES) or Pretreatment Standards for New Sources ( PSNS) is retained. The revised language appears as follows: " The Industrial User must demonstrate that it   currently uses control measures at least as effective as the control and treatment technologies that serve as the basis for that particular Standard."

The proposal discussed the fact that the pretreatment regulations in § 403.6( d) contain a strict prohibition against the use of dilution as a substitute for treatment, and that requirement remains. This provision indicates that no User introducing wastewater pollutants into a POTW may augment the use of process wastewater or otherwise dilute the wastewater as a partial or total substitute for adequate treatment to achieve compliance with a Pretreatment Standard. EPA believes that it is appropriate to require CIUs seeking to use an equivalent mass limit to demonstrate their past compliance with the dilution prohibition in § 403.6( d). See § 403.6( c)( 5)( i)( B). This requirement is intended to provide the Control Authority with a means of screening facilities so that a CIU that may have used dilution in the past is precluded from taking advantage of historically higher than necessary average flows to acquire a less stringent mass limit calculation. The Control Authority may review historical monitoring and inspection reports, and process descriptions from the appropriate categorical Standard Technical Development Document published with each categorical Standard, when evaluating the Industrial User's demonstration of no dilution and when selecting the appropriate average flow rate by which the equivalent mass limits are calculated. See § 403.6( c)( 5)( i)( B). The final rule also requires, as a condition of using mass limits, that Industrial Users " maintain the same or more effective control and treatment technologies as those that were in place at the time the equivalent mass limit is established." See § 403.6( c)( 5)( iii)( A).

( 3) Establishment of Average Daily Flow Rate and Baseline Long Term Average Production Rate: The proposal had indicated that it would be sufficient to provide a " reasonable estimate of the flow required to achieve the facility's production goals using BAT and in the absence of the water saving technology." See 64 FR 39570, July 22, 1999. The final rule changes this approach to require, consistent with current regulation and guidance, that equivalent mass limits be based on the CIU's long term average daily flow rate and that flows be measured, as opposed to estimated, using a continuous effluent flow monitor. The final rule requires that the flow rate used be representative of current operating conditions; the actual period of flow used to develop the equivalent limits should reflect actual current production and water usage. See § 403.6( c)( 5)( i)( C). EPA also conditions the use of mass limits on the continued use of an effluent flow monitoring device to record the facility's flow rates. See § 403.6( c)( 5)( iii)( B).

In addition, the preamble of the proposed rule suggested that the flow component of the 91 equivalent mass limit be based on estimated flows " required to achieve the facility's production goals." See 64 FR 39570, July 22, 1999. EPA did not discuss in the preamble how the mass limit may need to change if the Industrial User changed its production goals, resulting in potentially substantial changes in process wastewater flow. In a subsequent rulemaking specifc to an XL project, EPA required Industrial Users subject to equivalent mass limits to notify the Control Authority where " production rates are expected to vary by more than 20 percent from a baseline production rate" determined when the mass limit was first established. See § 403.19( b). The final rule has been modified to include a requirement for the Industrial User to provide the Control Authority with sufficient information to establish a baseline long term average daily production rate. See § 403.6( c)( 5)( i)( C). The Industrial User must also notify the Control Authority of substantial changes in the rate so that the Control Authority is given an opportunity to alter the equivalent mass limit in the event of such changes. See § 403.6( c)( 5)( iii)( C).

( 4) Use of Mass Limits for Relatively Uniform Operating Conditions: The final rule includes an additional requirement that the Industrial User demonstrate that it " does not have daily flow rates, production levels, or pollutant levels that fluctuate to such a degree that an equivalent mass limit cannot be appropriately established to control the discharge." See § 403.6( c)( 5)( i)( D).

( 5) Consistent Compliance with Standards: EPA has determined that it is appropriate for the use of equivalent mass limits to be restricted to CIUs which have had a history of consistent compliance with applicable categorical Pretreatment Standards prior to the Industrial User's request for equivalent mass limits. The final rule does not specify the period during which the CIU must have demonstrated full compliance, but allows the Control Authority to assess the available compliance records to the extent that they are representative of current operating conditions and reflect the Industrial User's understanding of the regulatory obligations that must be achieved for compliance with these and related regulations. See § 403.6( c)( 5)( i)( E).

[ Calculation of Equivalent Mass Limit: The final rule specifies how Control Authorities must calculate the initial equivalent mass limit. EPA indicates that the equivalent mass limit must be recalculated prior to the reissuance of the control mechanism, in order to reflect changes in the long term average daily flow rate. See § 403.6( c)( 5)( ii). This requirement is consistent with EPA's regulations which require that the flow rate be based on a reasonable measure of the Industrial User's " actual long term average flow rate" ( see § 403.6( c)( 4), emphasis added), and EPA's long standing guidance on deriving process flow rates ( Guidance Manual for the Use of Production Based Pretreatment Standards and the Combined Wastestream Formula, EPA833 B 85 201, September 1985).]

4. Summary of Major Comments and EPA Response Discretionary Use of Mass Limits: Several commenters raised concerns regarding who 92 would initiate the use of equivalent limits and how much discretion the Control Authority has in imposing these limits. A consistent theme raised among commenters representing Industrial Users was the concern that the proposed rule would enable the Control Authority to impose mass limits over the objection of the Industrial User. Where POTW and state commenters provided comments on this issue, they expressed concern that mass limits would create additional burden and generally emphasized that the decision to use mass limits to regulate a particular indirect discharger should be left to the POTW's discretion. EPA notes that these positions appear consistent with one another. The final rule allows for an Industrial User to request equivalent mass limits and emphasizes that the decision to convert concentration based limits to equivalent mass limits lies within the Control Authority's discretion. EPA does not anticipate that an Industrial User would request the implementation of equivalent mass limits if it would create an unacceptable amount of additional burden for the facility, nor would the Control Authority accept an undue burden upon itself if a benefit would not be foreseen.

What level of treatment must be in place prior to being eligible for equivalent mass limits? A few commenters objected to the proposal's requirement that in order to be eligible to use equivalent mass limits the Industrial User be utilizing control measures at least as effective as the model treatment technologies that serve as the basis for the particular categorical Standard. These commenters instead supported the availability of equivalent mass limits where the Industrial User could demonstrate that the concentration limits can be met without treatment. One POTW and an environmental organization took the opposite position, indicating that treatment must be in place prior to the use of equivalent mass limits. Today's final rule retains the requirement that the Industrial User be using control measures at least as effective as the control and treatment technologies that serve as the basis for that particular Standard. The final rule also requires that the same or more effective technologies be maintained and effectively operated at all times while the equivalent mass limits are in effect.

EPA is imposing this requirement for a number of reasons. First, the use of technologies equivalent to the model treatment technologies provides the Control Authority with a level of assurance that qualifying Industrial Users have not been meeting their concentration based Standards through dilution, which is prohibited in § 403.6( d). Second, although water conservation typically increases the concentrations of pollutants in the process wastewater prior to treatment, facilities with on site treatment typically show a reduction of pollutant loadings in the final effluent prior to its discharge to the POTW sewer system even where the facility has instituted water conservation. This reduction can be attributed to the fact that many wastewater treatment technologies are limited solely by physical/ chemical properties of the pollutants in the wastewater, and not by influent concentrations. Therefore, reducing the wastewater discharge flow, while still achieving the same post treatment pollutant concentration, will reduce the overall pollutant load from the facility. This is based on the assumption that the reduced wastewater flow to the treatment system will allow the system to more successfully treat the increased pollutant concentrations in the wastewater treatment influent stream. More information on water conservation techniques and methods can be found [ reference to e docket] in the memorandum 93 dated March 23, 2004 from Carey Johnston to the Public record for the Pretreatment Streamlining Rule, with subject " The Impacts of Industrial Water Re Use and Reduction Technologies on End Of Pipe Pollutant Concentrations and Loadings."

In assessing whether the Industrial User has installed adequate control and treatment technologies, the Control Authority should review the corresponding categorical Standard Development Document for potential control options. For instance, the Development Document for Effluent Limitations Guidelines and Standards for the Metal Finishing Point Source Category ( EPA 440/ 1 83/ 091, June 1983) identifies that PSES for the waste streams containing complexed metals is based on the segregation of the complexed metals waste stream with separate treatment for the precipitation of metals and the removal of suspended solids. A figure depicting the different model treatment technologies for the complexed metals and other wastestreams can be found in Figure 10 1 ( page X 2) of the Development Document. ( pages X 1 4, and XII 1)

The Control Authority might also review current trade association literature for other control options that have become available since the Development Document was produced, as well as sources available through EPA's " Sector Strategies" programs and EPA's Office of Compliance Assistance: http:// www. epa. gov/ sectors/ program. html, http:// www. epa. gov/ compliance/ resources/ publications/ assistance/ sectors/ notebooks/ index. html. Because many technical development documents for categorical Standards were published over a decade ago, the model or control treatment technologies considered by EPA in developing a categorical Pretreatment Standard may not be the most commonly used or state of the art treatment option currently available. However, as a starting point, the Control Authority should understand these technologies and consider their effectiveness when determining whether an equivalent mass limit is appropriate.

Prohibition Against Dilution: A few commenters indicated their concern that implementation of mass limits might allow Industrial Users to secure lenient standards through the calculation of equivalent mass limits based on flows that reflect diluted wastestreams. The proposal discussed the fact that the pretreatment regulations contain in § 403.6( d) a strict prohibition against the use of dilution as a substitute for treatment. This provision indicates that no user introducing wastewater pollutants into a POTW may augment the use of process wastewater or otherwise dilute the wastewater as a partial or total substitute for adequate treatment to achieve compliance with a Pretreatment Standard. This provision also states that the Control Authority may, appropriately, impose mass limitations on Industrial Users which are using dilution to meet applicable Pretreatment Standards in addition to the concentration based standards. EPA finds that it is necessary to require CIUs seeking to use an equivalent mass limit to demonstrate their past compliance with the dilution prohibition in § 403.6( d). This requirement is intended to provide the Control Authority with a means of screening facilities that may have used dilution in the past to preclude them from using higher than necessary flow rates to calculate a mass limit ( e. g., such as comparing its product to flow ratio to that of other facilities within its industry or why it uses the level of process water that it uses). 94 How should compliance status affect an Industrial User's eligibility to be regulated by equivalent mass limits? Several POTWs and one environmental organization recommended that the proposed rule be revised to require the Industrial User to demonstrate that it is able to maintain compliance with applicable Pretreatment Standards prior to water conservation and to restrict eligibility based on such compliance. EPA agrees with the commenters' suggestions. The final rule adopts the requirement that interested Industrial Users demonstrate and Control Authorities verify that the User has consistently complied with all applicable categorical Standards prior to the request to be subject to mass based limits. Compliance with the underlying categorical Standards is an appropriate benchmark for the Control Authority to use in determining the eligibility of an individual discharger. Where the Industrial User has demonstrated consistent compliance, the Control Authority will be given some level of confidence that the User will be able to adjust to the use of a limit that is considered equivalent to the concentration based Standard. It is EPA's view that the reverse is also true in that the lack of compliance may indicate a User's inability to comply with an equivalent limit. EPA is not specifying a minimum time period over which an Industrial User must be in consistent compliance. EPA notes that regulations in 40 CFR 403.12( o) require that Industrial Users maintain records of all information from any monitoring activities for a minimum of 3 years. These records should be reviewed and considered to the extent that they reflect compliance with current conditions.

Incompatibility of Mass Limits with Particular Industries: One trade association commented that the use of mass limits is incompatible with their industry due in large part to the fluctuating conditions in their operations. It is EPA's view that certain facilities do not have operations that are compatible with the use of equivalent mass limits. For example, a high degree of variability in a CIU's flows, production, or pollutant discharge levels will likely make it an inappropriate candidate to use mass limits to control its discharge. For this reason, the final rule now requires Industrial Users to demonstrate that it " does not have daily flow rates, production levels, or pollutant levels that fluctuate to such a degree that an equivalent mass limit cannot be appropriate established to control the discharge." See § 403.6( c)( 5)( i)( C).

Water Conservation as a Qualifier for Eligibility: Several commenters stated that the implementation of equivalent mass limits should not be restricted to Industrial Users that have already implemented water conservation measures. EPA agrees that this provision's intent is to encourage innovative water conservation methods and should not include the pre condition that Industrial Users have already employed water conservation measures. This will allow ongoing as well as future water conservation efforts by enabling both to use equivalent mass limits. Regardless of whether a facility's water conservation methods are ongoing or have yet to be implemented, this final rule does require that the Industrial User demonstrate that it will employ water conservation methods and technologies that will substantially reduce water use during the term of its control mechanism. The Industrial User is also required to employ water conservation to remain eligible for equivalent mass limits. 95 This final rule does not specify the amount of water conservation that should be achieved or that constitutes a substantial reduction in water use. EPA notes that several existing programs define thresholds that the Control Authority may consider for use in this context. For example:

  The final rule for the Pretreatment Community XL ( XLC) Site Specific Rulemaking for Steele County, MN ( 65 FR 59743) of 40 CFR 403.19( b), indicates that the participating industrial users committed as a group to reduce water usage by 10% over the initial 5 year project period.   National Metal Finishing Strategic Goals Program promotes a 50% water reduction from each particular participating industry's baseline 1992 water usage. goalhttp:// www. strategicgoals. org/ coregoals. cfm   EPA considers a ± 20% change in flow rate to be a significant change in a flow rate. See page 2 14 of the EPA Guidance Manual for the use of Production Based Pretreatment Standards and the Combined Wastestream Formula ( Sept. 1985 How do facilities employ water conservation?: Currently there are many water reduction technologies in use in manufacturing facilities across the United States. Many of the technologies that EPA evaluated when establishing the categorical standards included water conservation techniques and technologies. The Technical Development Document for a particular categorical standard is a valuable tool for information on these technologies. Technologies that reduce wastewater discharge rates usually increase the concentrations of pollutants in the wastewater leaving the industrial operation. However, for facilities with wastewater treatment systems on site, these technologies will still reduce the final effluent pollutant loading, because many of the wastewater treatment technologies are limited solely by physical/ chemical properties of the pollutants in the wastewater, and not by influent concentrations. Therefore, reducing the wastewater discharge flow, while still achieving the same post treatment pollutant concentration, can reduce the overall pollutant load from the facility.

In the Metal Finishing ( MF) industry, facilities apply flow reduction practices to process baths or rinses to reduce the volume of wastewater discharged. One method that conserves water is cascade rinsing: when water is reused from one rinsing operation to another, less critical rinsing operation, before being discharged to treatment. Facilities can also reduce water use by coordinating and closely monitoring rinse water requirements. Matching water use to rinse water requirements optimizes the quantity of rinse water used for a given work load and tank arrangement. More information on water conservation techniques and methods can be found in the memorandum dated March 23, 2004 from Carey Johnston to the Public record for the Pretreatment Streamlining Rule, with subject " The Impacts of Industrial Water Re Use and Reduction Technologies on End Of Pipe Pollutant Concentrations and Loadings."

Assessing how reduced discharges will impact POTWs: One commenter explained that EPA would be violating Section 307 if the Agency finalizes the proposal by failing to address the issue of whether the more highly concentrated wastestreams that would result from reduced water 96 consumption " would cause environmental harm at either the POTW or in the receiving stream or result in long term sediment contamination." It is not necessary for the Agency to conduct a separate assessment of how less water in the discharge will impact POTWs and receiving waters. EPA emphasizes that the use of equivalent limits to regulate individual Industrial Users does not relieve the Control Authority of the need to establish and enforce local limits in accordance with § 403.5( d) which are protective of the POTW operations and prevent pass through and interference. Consequently, the use of concentration limits in lieu of mass limits would not be authorized if it resulted in a violation of local limits approved under § 403.5( d). Furthermore, this provision may be implemented only following determination of its feasibility by Control Authorities, and not unilaterally by industrial users. Control Authorities' local limits will continue to ensure protection of the individual POTW operations and its receiving environment.

How should the equivalent mass limit be calculated? One POTW commenter suggested that EPA clarify how to calculate the Industrial User's equivalent mass limit in order to specify which flow to use. EPA agrees that it is important to provide specific instructions on how the equivalent limit is to be calculated, especially with regard to which flow rate is the correct one to use. Today's final rule at § 403.6( c)( 5)( ii) includes the following formula to be used to calculate the initial equivalent mass limits: the product of the facility's average daily flow rate and the applicable concentration based categorical daily maximum for the daily maximum mass, and the monthly average standard for the monthly average mass, and the appropriate conversion factor. As the flow rate is a long term average, it is important to note that the same flow value is used in the calculation of both the daily maximum and monthly average equivalent mass limits. [ Prior to the next term of the Industrial User's control mechanism, the collected flow data is assessed and the equivalent limit is recalculated to use the new long term average daily flow that has been continuously measured.]

Why are equivalent mass limits calculated using the long term average daily flow rate? EPA specifies in § 403.6( c)( 5)( ii) that the equivalent mass limits are calculated by multiplying the long term average daily flow rate [( either the initial " baseline" rate or the recalculated rate at the end of the control mechanism term)] by the applicable concentration based categorical Pretreatment Standard and the appropriate conversion factor. The use of the long term average daily flow rate as the flow basis for the limits is consistent with existing EPA regulations and guidance. The pretreatment regulations require the Control Authority to calculate " equivalent concentration limits" by using the " average daily flow rate of the Industrial User's regulated process wastewater." See § 403.6( c)( 4). The provision further states that " this average daily flow rate shall be based upon a reasonable measure of the Industrial User's actual long term average flow rate, such as the average daily flow rate during a representative year." CIUs are elsewhere required to report in the baseline monitoring report ( BMR) flow measurements showing the " measured average daily and maximum daily flow, in gallons per day, to the POTW" ( see § 403.12( b)( 4)) and to include in the periodic report " a record of measured or estimated average and maximum daily flows" ( see § 403.12( e)( 1)). 97 The use of long term average daily flows has also been consistently recognized in EPA's categorical Pretreatment Standards rulemakings. For instance, the rationale for the use of longterm average daily flow rates was described in the preamble to the final Pesticides Manufacturing Standard as follows:

" The use of the long term flow value, rather than maximum values from shorter time frames, is appropriate because the concentration values for the maximum daily and maximum monthly limitations were derived by multiplying the long term average performance level of well designed, well operated treatment systems by the respective variability factor for the treatment system. The variability factors already include, among other components, the variability associated with day to day and month to month production flow variations. As a result, the limitations are, in general, considerably less stringent than the long term averages achieved by the plants on which the limits and standards were based, and plants that design their operations and treatment systems to achieve the long term averages for individual pollutants should be able to achieve the limits and standards even during high flow days and months. The flow from any given day or month may not be representative of the plant's annual flow. Use of the highest monthly mean to set permit limits would provide duplicative allowance for variation in flow that is not justified, since the potential for high flow periods is already accounted for in the promulgated standards." See 58 FR 50679, September 28, 1993.

In addition, Chapter 2.8 of EPA's Guidance Manual for the Use of Production Based Pretreatment Standards and the Combined Wastestream Formula ( September 1985) describes important considerations when determining the appropriate flow rate for use in developing equivalent limits including that the same average rate is to be used to calculate both daily maximum and maximum monthly average alternative limits, to avoid the use of data for too short a time period ( particularly, " estimating the average rate based on data for a few high days, weeks, or months is not appropriate") ( page 2 14).

[ Likewise, it is important here to use a long term average that reflects current operating conditions. Use of flow data from a period that does not represent current production and water use would result in mass limits that are not equivalent. Thus, the period of time used to compute the long term average must reflect recent production changes as well as reductions in water use.]

Why are continuous effluent flow monitoring devices required? In allowing the use of equivalent mass limits, EPA is finalizing the proposed rule's change to enable Control Authorities to replace a standard expressed as a concentration value in the categorical Standards with an equivalent mass limit when issued in a control mechanism to an Industrial User. In allowing such action, EPA is authorizing Control Authorities to establish and enforce equivalent limitations for these CIUs. This equivalency means that the mass limit directly reflects the concentration value of the categorical Standard and that what the Control Authority is doing in adopting equivalent mass limits is merely a translation of the concentration value to a different unit of measurement through arithmetic multiplication.

( 1) Flow monitoring is required to ensure the equivalency to Federal categorical Pretreatment Standards: One commenter objected to the proposed rule stating that EPA lacks the authority to delegate its standard setting authority to Control Authorities, an authority which 98 Congress gave to EPA alone under Section 307 of the Clean Water Act. The commenter reasoned that the provision would require that local authorities make " significantly more complicated decisions than mere arithmetic", and that the proposal would require them to become " expert in both pollution control and water conservation in each regulated industry." EPA disagrees that the final rule illegally transfers the Agency's standard setting authority to Control Authorities. A Control Authority's use of an equivalent mass limit does not affect the underlying categorical Pretreatment Standard; the concentration based Standard is only replaced to the extent that it is correctly translated to an equivalent limit. When establishing the equivalent limit, the equivalency is only as good as the data used to characterize the existing conditions and the calculations performed to represent the equivalent limit. To ensure that equivalency is achieved, EPA is requiring that the flow value used in the translation of the concentration limit to the equivalent mass limit be based upon a measured value using a continuous flow measuring device. Similar to the setting of alternate mass or alternate concentration limits when using the Combined Wastestream Formula of 40 CFR 403.6( c), if equivalent mass limitations have not been developed as required, the Industrial User must achieve the concentration limitations published in the categorical Standard.

Several industry commenters and one trade association representing municipalities indicated that they would support the use of estimation methods to derive facility flow rates for establishing the mass limit and for determining compliance. These commenters emphasized that estimation methods have been proven to be accurate and cost effective. Some commenters supported the proposal's allowance for " a reasonable estimate of the flow  ", but did not indicate whether they would support a requirement to use only measured flows. Several commenters, including three states, 2 POTWs, and 1 environmental interest group agreed that the level of accuracy obtained from flow measurements, in contrast to flow estimation, is needed in order to ensure equivalency with the categorical Standards. These commenters stressed that flow measurement was necessary in order to adequately assess compliance with the equivalent standard. One state went so far as to declare that the proposal was flawed in that it had not required flow measuring devices. EPA concurs with those comments that supported measured flows.

( 2) The relative costs and benefits of using flow monitoring devices should be considered: In terms of the relative cost of implementing flow monitoring devices, the CIU and Control Authority may wish to evaluate the expense of the installation of the continuous flow measuring device with the benefits that may be achieved by institution of water conservation methods and technologies. Cost effective flow measurement devices are estimated to cost $ 400  $ 1500. In contrast, commercial/ industrial facilities using municipal water and sewer systems incur an average $ 28,000 monthly charge for their water and sewer use ( survey of 194 U. S. cities, conducted by Raftelis Financial Consulting), consisting of over $ 12,000 per month for water charges and over $ 16,000 per month for wastewater charges ( 2000 Water and Wastewater Rate Survey, Exhibit 2, page 19, and Exhibit 5, page 44). EPA believes that benefits of water conservation outweigh the cost of the meter and will be cost effective in many situations. 99 Specifically when initiating water conservation programs, EPA recognizes that water use habits must be changed so that water is used more efficiently. Accurate measurement of the water use is beneficial to identifying the amounts and usage of water so that behavioral practices can be modified and tracked. " Monitoring the amount of water used by an industrial/ commercial facility can provide baseline information on quantities of overall company water use, the seasonal and hourly patterns of water use, and the quantities and quality of water use in individual processes. Baseline information on water use can be used to set company goals and to develop specific water use efficiency measures. Monitoring can make employees more aware of water use rates and makes it easier to measure the results of conservation efforts. The use of meters on individual pieces of water using equipment can provide direct information on the efficiency of water use" ( Cleaner Water Through Conservation, EPA 841 B 95 002, April 1995, page 7). In addition to assisting the Industrial User's conservation program, the Control Authority has oversight obligations to independently assess the Industrial User's compliance with the limits. Accurate flow measurement is required to determine compliance with a mass limit based on a concentration sample result received from the laboratory. To such end, " Relying on water consumption records when determining compliance with mass based limits is not an acceptable practice" ( Industrial User Inspection And Sampling Manual For POTW's ( EPA 831 B 91 001, April 1994, page 88) and a permanent device that continuously records the flow allows the POTW to accomplish this requirement.

For compliance assessment purposes, EPA advises Control Authorities to use the following approach:

  For a daily maximum equivalent mass limit, compliance should be determined by comparing the limit with the total mass of the pollutant discharged over the day, calculated as the product of the actual pollutant concentrations in the Industrial User's discharge sampled pursuant to § 403.12( g) and the actual flow from the Industrial User on the day the sample is taken based on measurements from the continuous effluent flow monitoring device and an appropriate conversion factor.

  For an average monthly equivalent mass limit, compliance should be determined by comparing the limit with the sum of all daily mass discharges measured during a calendar month divided by the number of days measured during that month. The monthly limit must still be met when only one discharge day is sampled.

This approach is derived from the definition of " daily discharge" in § 122.2. " Daily discharge" is defined as the " discharge of a pollutant measured during a calendar day or any 24 hour period that reasonably represents the calendar day for purposes of sampling. For pollutants with limitations expressed in units of mass, the ` daily discharge' is calculated as the total mass of the pollutant discharged over the day. For pollutants with limitations expressed in other units of 100 measurement, the " daily discharge" is calculated as the average measurement of the pollutant over the day."

How are limits established for new Industrial Users? Several POTW commenters noted that the proposed rule was silent regarding whether equivalent mass limits would be available to new Industrial Users. The commenters observed that flow rate information is available for many existing Users, but a baseline of information will not exist for new dischargers. Today's final rule is silent regarding specific procedures to follow in establishing limits for new discharges, however, the rule does not prohibit Control Authorities from calculating equivalent mass limits for such dischargers. However, EPA does not recommend allowing new dischargers to utilize equivalent mass limits, since it may not be possible to meet the requirements in today's rule or be consistent with operational realities.

First, recognizing that § 403.6( c)( 5)( i)( E) requires the Industrial User to have had " consistent compliance" with Pretreatment Standards", before considering the use of equivalent mass limits, the Control Authority will need to allow for a sufficient period of time to pass in order to properly assess the User's compliance record.

Second, the new discharger will need some time to collect an adequate amount of flow rate data from its continuous effluent flow monitor to establish its average daily flow rate to provide the Control Authority with sufficient information to calculate the equivalent mass limits. Although § 403.6( c)( 5)( i)( C) does not specify a minimum amount of time over which the longterm flow rate is developed, the rule does specify that the flow rate must be " representative of current operating conditions." Therefore, EPA recommends that the Control Authority establish some minimum period of time during which it will require the new discharger to have monitored its flow before considering equivalent mass limits.

Third, new dischargers will be subject to Pretreatment Standards for New Sources ( PSNS), and as such will be expected to begin discharging in conformance with Standards that represent the most stringent controls attainable through the application of the best available demonstrated control technology for pollutants that pass through, interfere with, or are otherwise incompatible with the operation of POTWs. 67 Fed. Reg. 64219 ( October 17, 2002). EPA does not anticipate that new dischargers will be in a position to immediately need to reduce water use since they would have had the opportunity prior to commencing their discharge to implement optimal water consumption practices that meet their own production demands and cost efficiency standards. Over time, and after considering such factors as the cost of water and production needs, the facility may become interested in pursuing further water conservation measures.

[ Recalculation of Equivalent Mass Limit to Adjust for Production Changes During the Term of the Control Mechanism or Flow Changes Upon Reissuance of Control Mechanism: A few commenters were concerned that once set, the equivalent mass limits would be locked in place permanently and Industrial Users would be forced to comply with one mass 101 limit forever. They specified that this would potentially restrict a facility from increasing production. The final rule requires that the Industrial User notify the Control Authority whenever production rates are expected to vary by more than 20 percent from baseline production rate. Upon notification of a change in production rate, the Control Authority would then reassess the appropriateness of the equivalent mass limit. The Control Authority may determine that it is necessary to change the equivalent mass limit to reflect flow changes that may result from substantial changes in production. As such productionbased flow changes may occur, modifying the control mechanism is consistent with regulations at § 403.6( e) that discuss alternative limits based on the combined wastestream formula:

" The Industrial User shall comply with the alternative daily maximum limit and monthly limits fixed by the Control Authority until the Control Authority modifies the limits or approves an Industrial User modification request. Modification is authorized whenever there is a material or significant change in the values used in the calculation to fix alternative limits for the regulated pollutant."

EPA recognizes that a facility's flow rate may be significantly reduced due to to water conservation efforts during the term of the control mechanism. In contrast to EPA's long standing guidance on deriving process flow rates ( Guidance Manual for the Use of Production Based Pretreatment Standards and the Combined Wastestream Formula, EPA833 B 85 201, September 1985) which recommends that if the actual average flow rate changes by more than 20 percent from the basis used in the calculation of the equivalent limits, then the limits should be revised ( page 2 14), EPA is recommending that to encourage water conservation efforts, such recalculation based on a flow rate change alone ( i. e. the production rate remains constant) should be postponed until the end of the control mechanism. The final rule requires the Control Authority to recalculate the equivalent mass limit upon reissuance of the CIU's control mechanism to account for the facility's new long term average daily flow rate. This requirement is consistent with EPA's regulations which require that the flow rate be based on a reasonable measure of the Industrial User's " actual long term average flow rate" ( see § 403.6( c)( 4), emphasis added) that is " representative during the entire term of the permit or   control mechanism" ( see 58 FR 50679, September 28, 1993).

Commentary on the Use of Mass Based Limits: EPA may promulgate pretreatment standards ( and other effluent guidelines) in a number of ways including: ( 1) production normalized mass based ( mass pollutant/ production unit); ( 2) flow normalized mass based ( mass pollutant/ time unit); and ( 3) concentration based standards ( mass pollutant/ volume of wastewater). These three types of pretreatment standards can be converted to a mass based permit limit by using a reasonable measure of the Industrial User's actual long term daily production ( for production normalized mass based standards) or the Industrial User's actual long term average daily flow rate ( for 102 flow normalized mass based and concentration based standards).

EPA prefers setting production normalized mass based standards, where feasible, since production normalized limitations can require flow reduction and reduces any potential for the substitution of dilution for treatment. Specifically, production normalized mass based standards are calculated from production normalized flows ( volume of wastewater/ production unit) and incorporate wastewater flow reductions representing BAT ( technology basis for PSES) or Best Available Demonstrated Technology ( BADT, technology basis for PSNS). Flow normalized mass based and concentration based standards may include flow reduction when estimating the PSES and PSNS incremental compliance costs, however, the standards themselves do not specifically require flow reductions to maintain compliance. As discussed below, there are also environmental benefits in controlling industrial wastewater through mass based standards using concentration based standards and a reasonable measure of the Industrial User's actual long term average daily flow rate (" flow normalized mass based standards").

It is important to note that EPA allows for sufficient variability when promulgating pretreatment standards ( and other effluent guidelines) to maintain compliance at all times for a facility employing well operated wastewater pollution controls equivalent in performance to BAT or BADT. For more than 25 years EPA= s effluent guidelines program has used a statistical approach to calculate the appropriate variability factors when setting the maximum monthly average and maximum daily standards. This approach has been upheld by the Courts in numerous challenges. In the a recent Court decision, in a challenge of effluent guidelines limitations for the pulp and paper industry, National Wildlife Federation, et al. v. Environmental Protection Agency, No. 99 1452 ( D. C. Cir.) ( April 19, 2002), the Court said: ABriefly, the limitations are derived using the following process: EPA determines an average performance level, or long term average, that a well designed mill using the model technologies can achieve. Recognizing variability among treatment processes, pollutant concentrations, sampling, and analysis, EPA incorporates variability factors into the limitations to account for these sources of variability.@ The Court found that AEPA's approach to developing monthly limitations was reasonable. It established limitations based on percentiles achieved by facilities using well operated and controlled processes and treatment systems.@ ( Iron and Steel comment response document: Excerpt Number: IS10203 5).

It is also important to note that flow normalized mass based permit limit developed by the Control Authority must be equivalent to the promulgated concentration based pretreatment standard through use of the Industrial User's actual long term average daily flow rate. This equivalency is necessary as the purpose of pretreatment standards ( and other technology based effluent guidelines) is to Aresult in reasonable further progress toward the national goal of eliminating the discharge of all pollutants.@ See NRDC, 863 F. 2d at 1433 ( 9th Cir. 1988). An unfaithful conversion of the applicable 103 concentration based pretreatment standard to a flow normalized mass based permit limit through use of an inappropriate average facility daily flow rate would contravene this national goal and effectively transfer standard setting from EPA to the Control Authority. The average daily flow rate should be based upon a reasonable measure of the Industrial User's average daily flow for at least a 30 day period ( see ' 403.6( e)( 1)). Additionally, EPA " strongly urges the Control Authority to develop an appropriate process wastewater flow for use in computing the mass effluent or internal plant limitations based on water conservation practices," ( see July 9, 1993; 58 FR 36890). Finally, a permit may be modified during its term, either at the request of the permittee ( or another interested party) or on EPA's initiative, to increase or decrease the flow basis in response to a significant change in production ( 40 CFR 124.5, 122.62). A change in production could be an " alteration" of the permitted activity or " new information" that would provide the basis for a permit modification ( 40 CFR 122.62( a)( 1),( 2)) ( see July 9, 1993; 58 FR 36891).

There are environmental benefits in controlling industrial wastewater through mass based standards using concentration based standards and a reasonable measure of the Industrial User's actual long term average daily flow rate ( Aflow normalized mass based standards@). Facilities whose wastewater discharges are solely controlled by flow normalized mass based standards may elect to better control their wastewater discharges than what is required by the applicable pretreatment standards through better wastewater control technologies and pollution prevention practices ( i. e., resulting in lower pollutant concentrations in the discharged wastewater) or better water conservation practices ( e. g., resulting in less wastewater volume discharged from an industrial operation) or both. As demonstrated by numerous examples and case studies presented in the record supporting this final rule, implementing water re use and reduction technologies and pollution prevention practices generally reduce the amount of wastewater pollution discharged by industrial facilities. Specifically, reducing wastewater flow does not generally increase the pollutant concentrations in discharged effluent as: ( 1) water reduction technologies can also reduce the generation of pollution mass in the discharged wastewater ( e. g., change from a wet manufacturing operation to dry); ( 2) lowering the wastewater flow to an existing well operated and designed wastewater treatment system generally allows for better pollutant removal; and ( 3) pollutant concentrations discharged from a well operated and designed wastewater treatment system are generally constant despite fluctuations or increases in influent pollutant concentrations.

Consequently, given the option of controlling industrial wastewater discharges through either concentration based or flow normalized mass based permit limits, Control Authorities may elect to use flow normalized mass based permit limits to encourage water re use and reduction technologies and pollution prevention practices which will have the added benefit of reducing pollutant mass discharges. When opting to control industrial wastewater discharges though flow normalized mass based permit limits Control Authorities will need to consider the potential increase in administrative expenses and 104 potential enforcement difficulties.

Flow normalized mass based permit limits can be difficult for the Control Authority to implement. To develop a flow normalized mass based permit limit, the Control Authority must determine the actual average daily flow rate of the Industrial User's regulated process wastewater and then multiply that value by the appropriate promulgated concentration standard. This may be difficult in situations where the facility has highly variable production that leads to flows that often vary week to week or day to day. This is especially true for smaller facilities where: ( 1) the average daily flow rate of the Industrial User's regulated process wastewater may be infrequent or low and difficult to monitor; and ( 2) production tends to be more variable as the installation of equipment to provide flow equalization may not be practical. In addition, testing for compliance with the flow normalized mass based permit limit requires having accurate information on the flow from all regulated processes at the time the sample is taken. Testing for compliance with a concentration limit only requires taking the wastewater sample and comparing the sampled concentration to the limit. There have been difficulties in getting Control Authorities to correctly calculate flow normalized mass based permit limits, and in getting facilities to provide the necessary data to determine compliance with the applicable pretreatment standards. Deficiencies in permits and control mechanisms have in the past hindered enforcement actions against these facilities. Enforcing flow normalized mass based permit limits also becomes more complicated because there is an additional factor in the formula to calculate these limits. In order to measure compliance, both wastewater flow and pollutant concentrations at the sample point need to be accurate and verified in order to enforce the flow normalized mass based permit limits.

Current policy encourages Control Authorities to recalculate flow normalized mass based permit limits within the permit term when wastewater volume discharges increase or decrease by more than 20% from the Industrial User's actual long term average daily flow rate initially calculated at the beginning of the permit term. See " Guidance Manual for the Use of Production Based Pretreatment Standards and the Combined Wastestream Formula, EPA833 B 85 201, September 1985.@ To ease the administrative burden on Control Authorities and encourage water re use and reduction technologies and pollution prevention practices ( and the corresponding added benefit of reducing industrial wastewater pollutant mass discharges), EPA is now encouraging Control Authorities to recalculate the Industrial User's actual long term average daily flow rate only at the beginning of each permit renewal when wastewater volume reductions within the permit term are the result of water re use and reduction technologies and pollution prevention practices. In short, the Control Authority must recalculate the daily maximum and monthly average equivalent mass permit limits prior to the reissuance of the Industrial User's control mechanism based on the then current estimate of the Industrial User's actual long term average daily flow rate.]

Is this provision consistent with the Clean Water Act? One commenter objected to the proposed rule stating that EPA lacks the authority to delegate its standard setting authority to Control Authorities, an authority which Congress gave to EPA alone under Section 307 of the Clean Water Act. The commenter reasoned that the provision would require that local authorities make " significantly more complicated decisions than mere arithmetic", and that the proposal would require them to become " expert in both pollution control and water conservation in each regulated industry."

EPA is promulgating the changes to its pretreatment regulations in part under section 307( b) of the Clean Water Act. Section 307( b) clearly authorizes EPA from time to time to revise Pretreatment Standards as A control technology, processes, operating methods or other alternatives change.@ Therefore, today's action is not in violation of section 307( b) to the extent this provision amends the Pretreatment Standards for certain categories of industry subject to concentration based Standards. See list of affected industries in Section III. J. 3 above. As EPA has explained, the amendments to the regulations will facilitate both user's compliance and POTW oversight for industries engaging in water conservation, a practice EPA wants to encourage.

EPA disagrees that the final rule would illegally transfer the Agency's standard setting authority to Control Authorities.

EPA also disagrees with the commenter's observation that this provision would be too complicated for Control Authorities to use and oversee. EPA notes that the use of this provision is solely at the discretion of the Control Authority. If a particular Control Authority is concerned that it does not have the expertise to develop and oversee equivalent mass limits, today's final rule does not in any way allow the Industrial User to demand that the Control Authority convert existing concentration based Standards to equivalent mass limits or require that the Control Authority implement mass based limits if requested by the Industrial User. As a matter of daily implementation of approved Pretreatment Programs, States and POTW Control Authorities already conduct complex activities that demand advanced abilities: review Baseline Monitoring Reports ( § 403.12( b)) and other data to issue control mechanisms to Industrial Users, calculate production based standards and alternative limits using the Combined wastestream formula when necessary, and evaluate and assess the POTW plant processes to determine technically based local limits that are protective of pass through and interference.

Public Review and prior Approval Authority approval: Many commenters ( 21) did not support requiring public and/ or Approval Authority review of an Industrial User's proposed mass limit prior to Control Authority approval. Most were concerned that such a requirement would create additional administrative burden. EPA notes that this provision is intended to allow the permit limitation to be expressed in alternate units and is not anticipated to require a change in a Control Authority's enabling legislation to issue and enforce control mechanisms. Changes affecting individual industrial users are not substantial modifications within the principles of § 403.18( b)( 6). "' Changes to the POTW's control mechanism' refers to a change in the type of mechanism used ( e. g., permit versus orders) and not to change[ s] in one facility's permit or to changes in the boilerplate or other details of the permit." ( 62 FR 38408) However, the new equivalent limit is subject to review as part of routine Approval Authority oversight activities, such as a Pretreatment Compliance Inspection or a Control Authority Audit, as are other control mechanisms that implement categorical standards, local limits, and any other equivalent limits. Also, in accordance with current regulations, IU permit files and information necessary for determining permit limitations and compliance, must be publicly available. Therefore, EPA has decided not to require additional review or approval mechanisms for implementation of equivalent mass limits.

K. Oversight of Categorical Industrial Users ( 40 CFR 403.3( f)( 2)( v), ( v)( 2), 403.12( i), ( e), ( q)) Today's rule provides Control Authorities with the ability to reduce certain oversight responsibilities and sampling and inspection requirements for a new class of indirect discharger, the " non significant categorical Industrial User" ( NSCIU). [ A NSCIU is a discharger which discharges no more than 100 gallons per day of total process wastewater to the POTW.]

1. What are the existing rules?

The current regulations require certain minimum oversight of SIUs by POTWs with Approved Pretreatment Programs ( and States acting as Pretreatment Control Authorities). The required minimum oversight includes inspection and sampling of each SIU annually, reviewing the need for a slug control plan, and issuing a permit or equivalent control mechanism at least every five years ( 40 CFR 403.8( f)( 1)( iii) and ( 2)( v) and 403.10( f)( 2)( i)). Industrial users that are not SIUs are not necessarily subject to this oversight.

The definition of " Significant Industrial User" at 40 CFR 403.3( t) includes two types of facilities. The first includes all industrial users that are subject to categorical Pretreatment Standards under 40 CFR 403.6 and 40 CFR chapter I, subchapter N. The facilities subject to these standards are referred to as categorical industrial users ( CIUs). There are no current exceptions to the inclusion of CIUs in the definition of an SIU. The second category of facilities included in the definition of SIU are certain facilities that are not CIUs, that discharge 25,000 gallons per day or more of process wastewater, facilities that contribute a process wastestream constituting 5 percent or more of the POTW's capacity, and any industrial user that the Control Authority designates on the basis that it has a reasonable potential for adversely affecting the POTW's operation or for violating any pretreatment standard or requirement. The Control Authority may exclude facilities meeting any of the second category's criteria from the SIU definition based upon a finding that it does not have a reasonable potential to adversely affect the operation of the plant or violate any Pretreatment Standard or requirement. However, a CA is not able to make a similar exclusion for facilities meeting the definition of CIU.

The regulations require that all CIUs submit to their Control Authority twice per year, unless required more frequently, a report indicating the concentration of pollutants in their effluent which are limited by the applicable Categorical Pretreatment Standards ( 40 CFR 403.12( e)( 1)). The report must contain the results of sampling and analysis of the effluent which is representative of conditions occurring during the reporting period at a frequency necessary to assess and assure compliance with applicable standards ( 40 CFR 403.12( g)). The regulations make clear that these are minimum requirements and Control Authorities have the flexibility to increase sampling and reporting requirements.

2. What changes did EPA propose?

EPA proposed to allow Control Authorities to exempt certain CIUs from the definition of SIU. The proposal would have defined " non significant categorical industrial user" ( NSCIU) as ( 1) facilities that never discharge untreated concentrated wastes that are subject to the categorical Pretreatment Standard as identified in the development document for the standard, and never discharge more than 100 gallons per day ( gpd) of other process wastewater, and ( 2) industrial users subject only to certification requirements after having met baseline monitoring report requirements ( e. g., pesticide formulators and packagers).

In conjunction with the establishment of a NSCIU category, EPA also proposed that such users not be subject to minimum inspection and sampling requirements. Instead, the new requirements would have allowed the Control Authority to establish the appropriate level of inspection and sampling for these facilities. In addition, EPA would have established new minimum reporting requirements for NSCIU. EPA proposed that at a minimum, a non significant facility would be required to annually report and certify its status as a non significant facility, and certify that it is in compliance with the applicable Pretreatment Standards. A Control Authority could have required more frequent sampling, inspections, or reporting as it finds necessary to ensure compliance with the categorical standards.

3. What changes is EPA finalizing in today's rule?

Today's final rule adopts the proposed definition of " non significant categorical industrial user" ( NSCIU) and the proposal's concept of authorizing reduced oversight for such Users. A few modifications, which will be detailed further below, were made to the proposed provisions in response to concerns raised by commenters. [ The final rule retains the 100 gpd threshold for defining a NSCIU, as well as the condition that the User never discharge " untreated concentrated wastes".] Similar to the proposed rule, in order to be considered an NSCIU, the User must fulfill its annual certification requirement. The final rule also retains the Control Authority's discretion to reduce the NSCIU's sampling and reporting requirements as long as the User annually reports and certifies that it still meets the definition of a NSCIU. In addition, because the User is no longer considered an SIU, there is no requirement to issue a control mechanism. POTWs are also required to provide a list of the facilities that are being regulated as non significant in the POTWs annual pretreatment report. After an initial list is provided, deletions and additions should be keyed to the previously submitted list.

Regardless of whether an Industrial User is determined to be a NSCIU, it is still considered a categorical discharger and, as such, is still required to comply with applicable categorical Pretreatment Standards and related reporting requirements in 40 CFR 403.12( e) and 403.12( q). Control Authorities would still be required to perform the same minimum oversight of a NSCIU that is required for other facilities that are not SIUs, including notifying the CIU of its status and requirements ( 403.8( f)( 2)( iii)); receiving and reviewing required reports ( 403.8( f)( 2)( iv) and 403.12( b), ( d), & ( e)); random sampling and inspection ( 403.8( f)( 2)( v)); and investigating noncompliance as necessary ( 403.8( f)( 2)( vi)).

[ Why did EPA choose the 100 gpd threshold for NSCIUs: EPA recognizes that any numeric flow cutoff will have both advantages and disadvantages. The 100 gpd criterion was supported by commenters, although many suggested alternative, higher volume cutoffs. The 100 gpd flow cutoff is a conservative number. EPA estimates 11 percent of current CIUs might be eligible for NSCIU status, according to a recent nationwide evaluation of POTWs.]

Does EPA expect the annual NSCIU certification to be supported by sampling data: Today's final rule does not require that each certification statement be supported by sampling data. NSCIU facilities, however, must have a reasonable basis for their compliance certifications. When sampling is not performed, the non significant facility must describe the basis for its compliance certification, such as no changes in any processes that generate process wastewaters or no change in raw chemicals used.

Does EPA expect the industrial user or control authority to perform annual monitoring: Today's final rule does not establish any minimum sampling requirements for the industrial user or control authority. However, EPA recommends that sampling by the industry or Control Authority be performed from time to time to confirm compliance with the categorical Standards.

Significant changes to the proposed rule EPA made the following significant changes to the provisions affecting NSCIUs:

[ Discharge Volume Cutoff: The definition of NSCIU specifies that the 100 gpd cutoff is to be measured as the " total process wastewater ( excluding sanitary, non contact cooling and boiler blowdown wastewater)" discharged. The term " total" clarifies that the volume discharged is a maximum limit. Averaging the discharge volume for purposes of meeting the 100 gpd cutoff is not authorized ( e. g., enabling a discharger to exceed the limit on some days as long as the average is 100 gpd or less). EPA had requested comments in the proposal on whether to allow the non significant definition to include facilities that discharge up to 500 gallons of process wastewater once per week. EPA is still of the opinion that requiring a definitive, total daily cutoff is the easiest and most efficient way to oversee and implement the NSCIU provisions.]

Also, the definition of NSCIU specifically enables Users to exclude non process wastewater discharges such as sanitary, non contact cooling and boiler blowdown wastewater. See § 403.3( v)( 2).

Additional Definitional Conditions: The final rule includes a few modifications to the conditions that a User must meet to be considered " non significant". These modifications include:

( 1) Consistent Compliance with Pretreatment Standards: In order to be considered an NSCIU, the User, prior to the Control Authority's findings, must have consistently complied with all applicable categorical Pretreatment Standards and Requirements. See § 403.3( v)( 2)( i) and discussion above regarding the consistent compliance criteria for equivalent mass limits. ( 2) Documentation and Certification of Compliance: The final rule also requires that the NSCIU certify that its discharge is in compliance with all applicable categorical pretreatment standards and requirements and annually submit the certification using the statement in § 403.12( q). See § 403.3( v)( 2)( ii).

Signatory Requirements: Today's final rule clarifies that the annual certification statement must be signed in accordance with requirements in § 403.12( l). See § 403.12( q).

Annual List of NSCIUs: The final rule makes explicit what was discussed in the preamble to the proposed rule that Control Authorities are required to include a list of Users considered to be NSCIUs in its annual report to the Approval Authority. See § 403.12( i).

Annual Evaluation of NSCIU Status: The proposed rule is modified to require that Control Authorities evaluate, at least once per year, whether Industrial User previously determined to be an NSCIU still meets the " non significant" criteria in § 403.3( v)( 2). See § 403.8( f)( 2)( v).

4. Summary of Major Comments and EPA Response Do POTW's need to conduct annual inspections or sampling of NSCIUs? Several commenters recommended that EPA specifically reduce oversight of NSCIUs by limiting Control Authority inspections and/ or sampling. The recommended frequencies ranged between every other year to as often as once per year. Other commenters supported completely eliminating inspection and sampling requirements. With the adoption of today's rule, EPA is not establishing any minimum inspection and sampling requirements for NSCIUs. Today's rule instead requires the Control Authority to perform an evaluation, at least once per year, on whether the NSCIU meets the criteria of § 403.3( v)( 2). As part of the annual evaluation, EPA recommends that the Control Authority conduct an on site inspection of the facility in order to maintain awareness of the facility's process and to determine to the extent possible whether the discharger is complying with its Pretreatment Program requirements. As part of the evaluation, the Control Authority should verify the NSCIU's certification under § 403.12( q) and review any other documentation provided by the facility. The level of effort devoted to an inspection can be tailored to the facility. The Control Authority is not required to issue the NSCIU a control mechanism. However, the CA could, on a case by case basis, determine whether individual control mechanisms are necessary for NSCIUs and develop adequate sampling and inspection frequencies.

One commenter suggested that some type of annual correspondence, at minimum, be incorporated into the pretreatment regulations to remind the NSCIU and Control Authority of their responsibilities and obligations under the Pretreatment Program. EPA agrees with the comment and has modified the rule language to include requirements that NCSIUs annually certify they are in compliance with all applicable pretreatment standards using the certification statement at 403.12( q). Further, the Control Authority must annually review the NSCIU's § 403.12( q) certification statement, perform a NSCIU evaluation, at least once per year, and provide an updated list of NSCIUs to the Approval Authority as part of its annual POTW pretreatment report.

Can EPA provide some clarification of the NSCIU definition? Commenters expressed the need for clarification in the proposed definition of NSCIU. Several commenters were concerned that the language, as proposed, would allow Control Authorities to exempt a greater number of Industrial Users from Pretreatment Program requirements than what was intended under the proposal. These commenters interpreted the proposed definition to potentially allow an unlimited amount of treated concentrated wastewater ( the proposal prohibited " untreated concentrated wastes") to be discharged to the POTW while still falling under the NSCIU threshold since it only required that discharges of " other process wastewater" not be more than 100 gpd. Many commenters stated that a CIU could be deemed " non significant", under the proposed definition, if it could merely demonstrate that it did not discharge " untreated concentrated wastes" subject to the categorical Pretreatment Standards and not more than 100 gpd of other process wastewater. Upon further consideration, EPA agrees that the proposed criteria for becoming a NSCIU was open to more than one interpretation and has revised the language in the final rule to further clarify the definition. Therefore, with the adoption of today's rule, EPA is clarifying the NSCIU definition to include " 100 gpd of total process wastewater" in order to emphasize the fact that it is the " total" discharge of 100 gpd or less of process wastewater which qualifies a User for NSCIU status ( as long as the other required conditions of § 403.3( v)( 2) are met), not some smaller subset of treated concentrated wastewaters. EPA has also deleted the word " other" and has added conditions that must be met prior to designation of a nonsignificant categorical industrial user.

[ Why didn't EPA promulgate a higher flow threshold? Many commenters supported the concept of creating a flow cut off threshold, but suggested that the 100 gpd ceiling was too low. Commenters suggested alternative flow thresholds ranging from 300 gpd to 25,000 gpd, and also suggested that facilities that have little or no potential to impact the operation of the receiving POTW be included in this classification. Other POTW commenters supported the position of the Association of Metropolitan Sewerage Agencies ( AMSA, now renamed as the National Association of Clean Water Agencies) which proposed an alternative cutoff which was specific to the POTW. The AMSA approach proposed that a discharge of process wastewater no greater than 0.01% of the treatment plant's design hydraulic or organic treatment capacity, and no greater than 0.01% of the maximum allowable headworks loading ( MAHL) for the receiving POTW of any categorical pollutant detected at the POTW headworks, as long as the discharge did not exceed 10,000 gpd and the CIU was not in significant noncompliance for the previous two years, would be considered an NSCIU. EPA notes that the comments provided did not establish data to support how many CIUs would potentially be captured by the different flow thresholds, nor did they provide information on the impact of these alternative criteria on Pretreatment Program results.

EPA's intent in establishing the NSCIU category was to reduce the burden on Control Authorities of regulating Industrial Users which could truly be considered of minimal impact to the treatment plant and the Pretreatment Program in general. It was not EPA's intention to remove a large segment of contributing CIUs from Pretreatment Program oversight, and the Agency had an extremely limited amount of flow or other discharge data from which to establish with any certainty the impact on the Pretreatment Program of allowing the NSCIU category to capture a greater number of Users. EPA generally views the 100 gpd threshold as capturing the de minimus dischargers, and supports retaining the existing level of reporting, sampling, and inspection requirements to the remaining SIUs. In addition, in relation to the suggestion that EPA adopt a percentage of Control Authority flow as a basis for level of oversight and control, EPA notes that such an approach would have the effect of undermining the technology driven level playing field created by the categorical Standards by establishing a threshold that benefits larger sized POTWS as compared to smaller systems. Furthermore, EPA estimates that approximately 86% of the POTW universe has 10 or fewer CIUs.

In the proposal EPA estimated that about 2 percent of the current CIUs might be eligible for non significant status. A recent evaluation of 75 POTW Pretreatment Programs indicated that an average of 11 percent of all CIUs in those municipalities would meet the 100 gpd threshold for NSCIU. EPA anticipates that the 100 gpd threshold will result in capturing higher numbers of CIUs in select cities or regions. In comparison, in the public comments responding to the proposed rule, one commenter stated that 5 of its 38 ( or 13%) dischargers would be covered under the 100 gpd cutoff, while another commenter indicated that 1 of its 4 ( or 25%) dischargers would be covered under the 100 gpd threshold.

One commenter was opposed to any higher flow or narrative threshold for batch dischargers based on the fact that the proposal would have eliminated minimal, but critical, requirements for annual inspection and sampling, biennial slug control plans, permit reviews once every 5 years, while ignoring the compliance history and the discharger's potential to harm the POTW. EPA wishes to clarify that a Control Authority will have discretion to designate certain CIUs as NSCIUs if they meet specific criteria, and to exercise that discretion in the case of any individual CIUs, but will not be obligated to obtain or exercise this discretion in any particular case. Although certain facilities may be considered NSCIUs, EPA does not specify what types of reporting requirements are necessary. Although the Control Authority may choose a lesser amount of currently required sampling and reporting, the final rule does not mandate this decision. As stated above, EPA does require that the Control Authority conduct at a minimum an annual evaluation. EPA recommends that this evaluation be in the form of an annual inspection. EPA has also created conditions that address the commenter's concern about facility compliance. For example, to be eligible for NSCIU status, a facility must have consistently complied with all applicable categorical Pretreatment Standards and Requirements prior to the Control Authority's findings. Further, the NSCIU must certify on an annual basis ( per the certification requirement in § 403.12( q)) that its discharge is in compliance with all applicable categorical Standards and Requirements. Can averaging be allowed in the NSCIU determination? EPA solicited comment on whether averaging should be allowed in determining whether a CIU fell under the 100 gpd threshold. Several commenters indicated that they concurred with the 100 gpd flow threshold, but suggested that the Agency include facilities that discharge up to 500 gallons per week. Today's final rule does not authorize the use of averaging to meet the 100 gpd threshold. EPA is concerned that allowing such an approach could be difficult to oversee from the Control Authority's perspective, and could be burdensome to implement from the CIU's perspective. A greater degree of precision and a higher frequency of reporting would be needed to support a threshold that allows for averaging flow values. Because the 100 gpd approach is applied as a threshold which cannot be exceeded, it can be implemented in a more straightforward manner which is expected to minimize the opportunity for misinterpretation. If a facility is a batch discharger and currently discharges more than 100 gpd EPA recommends that industrial user install some form of flow restrictor that will ensure that they never go over 100 gallons on any single day. ]

Does a facility have to treat its wastewater to be considered non significant? Several commenters expressed concern that it appeared from the proposal that a facility would need to install and provide treatment for all its wastewater prior to discharge. EPA clarifies that a facility does not need to have treatment in place in order to be considered non significant, consistent with the fact that the categorical Standards do not dictate what types of treatment technologies the CIU must use and the facility's discharge, with or without treatment, would remain in compliance with the categorical Standard. The Standards only provide the limits with which any Industrial User's discharge must comply. On the other hand, the final NSCIU criteria require that the facility not discharge any " untreated concentrated wastewater" since it may be assumed that untreated concentrated ( i. e., plating baths and rinses, solvents, sludges, etc.) wastewater would not be in compliance with the categorical Standard. Regardless of whether treatment exists at the CIU, the final rule requires that the facility must have consistently complied with all applicable categorical Pretreatment Standards and Requirements in order to be considered an NSCIU. Furthermore, the facility must, at minimum, annually certify that its discharge is in compliance with all applicable categorical pretreatment standards and requirements.

IV. Description of Areas Where EPA Is Not Taking Action on the Proposed Rule A. Specific Prohibition Regarding pH ( 40 CFR 403.5( b)( 2))

This section discusses EPA's proposal to amend 40 CFR 403.5( b)( 2) to authorize the introduction of discharges with pH less than 5.0 in certain circumstances. EPA has decided not to adopt the proposed changes to 40 CFR 403.5( b). EPA concluded that inadequate scientific information was available to determine the effects of short term, low pH discharges on the integrity of the POTW collection systems to support a change to the current prohibition on the introduction of discharges with a pH lower than 5.0 into POTWs. 1. What is the existing rule?

Acidic wastes can corrode sewer pipes with a resulting release of pollutants into the environment. To address this concern, the current regulations include a limit on the acidity of wastes, a minimum pH limit, in the specific prohibitions at 40 CFR 403.5( b). This prohibition applies to all nondomestic dischargers to POTWs. Section 403.5( b)( 2) prohibits the discharge of " pollutants which will cause corrosive structural damage to the POTW, but in no case discharges with pH lower than 5.0, unless the works is specifically designed to accommodate such Discharges."

2. What changes did EPA propose?

EPA proposed to allow POTWs with Approved Pretreatment Programs to authorize temporary excursions below pH 5.0 provided that the POTW maintain a written technical evaluation supporting the finding that the alternative pH requirements did not have the potential to cause corrosive structural damage to the POTW or otherwise violate 40 CFR 403.5( a) and ( b). This change would have allowed POTWs to accept discharges below pH 5.0 from industrial users that continuously monitored the pH of their discharges, or to accept such temporary excursions by a limited group of industrial users. EPA proposed that any alternative pH requirement developed by a POTW would be enforceable as a Pretreatment Standard under the Clean Water Act. ( The general narrative prohibition against pollutants that cause corrosive structural damage at 40 CFR 403.5( b)( 2) would still have applied.)

3. What action is EPA taking today?

EPA has decided not to adopt any changes to 40 CFR 403.5( b)( 2). The existing specific prohibition against discharges with pH lower than 5.0 will remain in effect.

In arriving at this decision, EPA has found that most of the current literature on the relationship between low pH and corrosion of sewer pipes is general and qualitative. References rarely address short term discharges of low pH and tend to only discuss effects of continuous exposure. Furthermore, predicting the effects of corrosion on POTW sewer pipes is complicated by a variety of factors, including wastewater characteristics such as pH, temperature, volume, velocity, turbulence, alkalinity, dissolved oxygen, as well as sewer pipe characteristics such as size, age, material of construction, pipe configuration, and time since last cleaning. Many POTW's are currently installing linings to their pipes consisting of various materials to stop . There is no data on what effects pH may have on these new materials. EPA has concluded that until research is available that investigates the synergistic effects of these factors as well as further data on the effects of short term discharges of low pH and therefore modifications to the current regulations are not appropriate at this time.

What significant changes were made to the proposed rule? EPA has decided not to change the current rule regarding discharges less than pH 5.0. EPA lacks sufficient information on the effects of short term or long term discharges with pH lower than 5.0 on the structural integrity of POTWs. The current regulations at 40 CFR 403.5( b) remain in effect.

4. Summary of Major Comments and EPA Response Many commenters gave qualified support for the proposed modifications with suggestions for implementation. EPA received comments on the proposed rule stating that the proposal did not adequately protect POTWs. One commenter cautioned that systems constructed of acid resistant materials often include manhole inverts constructed of concrete and similar materials that are susceptible to corrosion, and are thus rarely entirely resistant to such effects. Some requested that EPA make the current pH limit more stringent ( i. e. above pH 5.0) because there are systems that are currently experiencing corrosion damage. A few commenters questioned whether the proposed modifications would actually provide a significant burden relief for POTWs, on the basis that adequate evidence does not exist that shows POTWs devote a substantial amount of resources to dealing with short term violations. Several commenters requested guidance on various implementation topics, including how POTWs should assess and maintain the integrity of their systems with respect to corrosion. These outstanding issues influenced EPA= s decision not to finalize the proposed modifications at this time.

Even though EPA has decided not to finalize this proposed provision, all comments that were submitted on the proposal will be carefully considered as EPA further explores the issue of short term pH discharges. Please see the Response to Public Comment Document for responses to specific comments.

Application of 40 CFR 401.17 Criteria: Some commenters suggested that the pH provisions at 40 CFR 401.17 could serve as a basis for alternative pH requirements. The effluent guideline regulations list certain conditions under which excursions from pH limits are allowed for direct dischargers. EPA developed 40 CFR 401.17 based on the Agency's determination that direct dischargers could continuously meet a pH limit between 6.0 and 9.0. In comparison, pretreatment requirements are based on preventing corrosion in POTWs and are much less restrictive. It is EPA's view that it would be inappropriate to attempt to use 40 CFR 401.17 as a basis for alternative pH requirements because the reason behind establishing the pH requirement is different. However, POTWs may implement and enforce local pH limits in a manner that is more stringent than the federal regulations. EPA refers commenters to EPA's May 13, 1993 letter to Mary Jo M. Aiello of the New Jersey Department of Environmental Protection and Energy, for a discussion of an acceptable analogous application to the pretreatment program. See http:// www. epa. gov/ npdes/ pubs/ owm0113. pdf.

Use of Enforcement Response Plans to Address pH Violations: Several POTW commenters expressed concern over the level of burden imposed on them by the existing pH limit since they are obligated to treat all exceedances as violations. In EPA's view, it is relevant to clarify the inherent flexibility present in a POTW's Enforcement Response Plan provisions to define varying levels of response to temporary pH violations. EPA advises POTWs to incorporate a preferred method of dealing with violations of local limits into their Enforcement Response Plans and refers commenters to the Guidance for Developing Control Authority Enforcement Response Plans ( EPA, 1989). See http:// www. epa. gov/ npdes/ pubs/ owm0015. pdf. EPA notes that POTWs make their own decisions regarding the utilization of resources in response to low pH discharges when developing an Enforcement Response Plan. Excursions under pH 5.0 are pretreatment standard violations ( 40 CFR 403.5( b)( 2)), and, in determining the appropriate response, EPA recommends that the Control Authority consider the following criteria: frequency, duration, magnitude, effect, and/ or compliance. A record should be made of the response, and the person responsible for screening the data should alert enforcement personnel to the noncompliance. EPA recognizes that the Control Authority's appropriate response ( including no further action, a phone call, or a notification letter) may vary. This flexibility may help reduce the burdens on the commenters' programs.

V. Changes to part 122 EPA is also making the following changes to the part 122 regulations:

  § 122.21( j)( 6): Change reference to definition of " Significant Industrial User" to § 403.3( v), instead of § 403.3( t). This reference change is a direct result of renumbering associated with today's rule.

  § 122.44( j)( 1): Correct typographical error referring to " significant indirect dischargers" instead of the correct term, " significant industrial users".

  § 122.62( a)( 7): Correct typographical error referencing an incorrect provision relating to modifications. The correct reference should be § 403.18( e).

VI. Considerations in Adopting Today's Rule Revisions How does a POTW adopt today's rule provisions? Section 40 CFR 403.18( a) generally requires review and approval by the Approval Authority of modifications to the POTW Pretreatment Program when there is a " significant change in the operation of a POTW Pretreatment Program that differs from the information in the POTW's [ program] submission   ." Consistent with this rule, before many of today's streamlining provisions may be implemented by local pretreatment authorities, POTWs will need to modify their Pretreatment Program procedures and authorities. Once the POTW has proposed all the program revisions it wishes in response to today's streamlining provisions, the modifications must then be submitted to the Approval Authority ( either the State, if Pretreatment Program authority, or the EPA Regional Authority) for approval. The regulations also require that the program modification be accompanied by a statement of basis for the changes, a description of the modifications and other information the Approval Authority may request as appropriate. See 40 CFR 403.18( c)( 1).

Although not required as part of today's final rule, EPA encourages a POTW to submit its Pretreatment Program modifications to its Approval Authority as a package, rather than sending changes piecemeal. This will help make the review process more efficient and less burdensome.

Is the POTW required to make any of today's streamlining changes? EPA notes that many of today's streamlining provisions are changes that the POTW may adopt at its discretion. Many of these changes ( e. g., the authority to use general control mechanisms, monitoring waivers for pollutants neither present nor expected to be present, BMPs in lieu of numeric local limits, and application of equivalent concentration limits in place of flowbased mass limits for OCPSF, petroleum refining, or pesticide chemicals facilities, creation of a category of non significant CIUs, and application of equivalent mass limits for concentration based categorical standards) involve features that provide program flexibility and are not required to be incorporated into the POTW's Pretreatment Program.

However, a few of today's rule provisions are changes that the POTW is required to make because they clarify certain minimum requirements, and to the extent that the POTW's approved program is inconsistent with these requirements, it would need to be modified. These required changes include:

( 1) 40 CFR 403.8( f)( 1)( iii)( B)( 6): clarification that slug control requirements must be referenced in SIU control mechanisms. The POTW is required to adopt this change because it specifies new minimum requirements for all SIU control mechanisms. ( 2) 40 CFR 403.8( f)( 2)( viii)( A)( B)( C): revisions to the significant noncompliance ( SNC) definition. These revisions are required because they expand the definition of SNC to include additional types of Pretreatment Standards and Requirements which were not clearly covered in previous definition. ( 3) 40 CFR 403.12( g): modifications to the sampling requirements and a clarification to the requirement to report all monitoring results. SIUs are now required to follow sampling requirements in 40 CFR 403.12 for periodic compliance reports ( 40 CFR 403.12( e)), whereas they were previously only explicitly applicable to baseline monitoring reports and 90 day compliance reports. Also, the final rule now requires that non categorical SIUs report all monitoring results, whereas the previous regulations only made this requirement explicit for categorical SIUs. The POTW is required to adopt these revisions because they set new minimum requirements for sampling and notification.

What is the difference between a " substantial modification" and a " non substantial" modification?

Different review procedures apply to program modifications depending on whether the modification is substantial or non substantial. Consequently, upon receiving the POTW's amended program submission, the Approval Authority must first determine whether any of the modifications constitute a " substantial modification" ( as defined in 40 CFR 403.18( b)) or a " nonsubstantial modification". Substantial modifications generally involve changes that may potentially result in a significant impact on the operation of the pretreatment program, increased pollutant loadings to the POTW, or less stringent requirements being imposed on Industrial Users. The pretreatment regulations specify that substantial modifications consist of one of seven potential changes to the POTW's program. See 40 CFR 430.18( b)( 1 7). All other changes to the program are considered non substantial.

The Approval Authority's review of a substantial modification, unlike a non substantial modification, must follow the same procedures used for approving the initial POTW pretreatment program, including the issuance of a public notice to inform the public of the POTW's modification submission. In comparison, where the submission, or parts of it, is reviewed as a non substantial modification, the Approval Authority has 45 days to either approve or disapprove the modification. Where the Approval Authority does not notify the POTW within 45 days of its decision to approve or disapprove the modification, or to treat the modification as substantial, the POTW may implement the modification as if it was approved.