Virginia Administrative Code
Title 9 - ENVIRONMENT
Agency 25 - STATE WATER CONTROL BOARD
Chapter 31 - VIRGINIA POLLUTANT DISCHARGE ELIMINATION SYSTEM (VPDES) PERMIT REGULATION
Part VII - General Pretreatment Regulations for Existing and New Sources of Pollution
Section 9VAC25-31-790 - Removal credits

Universal Citation: 9 VA Admin Code 25-31-790

Current through Register Vol. 41, No. 3, September 23, 2024

A. General.

1. Definitions for the purpose of this section:

"Removal" means a reduction in the amount of a pollutant in the POTW's effluent or alteration of the nature of a pollutant during treatment at the POTW. The reduction or alteration can be obtained by physical, chemical or biological means and may be the result of specifically designed POTW capabilities or may be incidental to the operation of the treatment system. Removal as used in this subpart shall not mean dilution of a pollutant in the POTW.

"Sludge requirements" means the following statutory provisions and regulations or permits issued thereunder (or more stringent Virginia or local regulations): § 405 of the CWA; the Solid Waste Disposal Act (SWDA) ( 42 USC § 6901 et seq.) (including Title II more commonly referred to as the Resource Conservation Recovery Act (RCRA) ( 42 USC § 6901 et seq.) and Virginia regulations contained in any Virginia sludge management plan prepared pursuant to Subtitle D of SWDA); the Clean Air Act ( 42 USC § 4701 et seq.); the Toxic Substances Control Act ( 15 USC § 2601 et seq.); and the Marine Protection, Research and Sanctuaries Act ( 33 USC § 1401 et seq.).

2. General. Any POTW receiving wastes from an industrial user to which a categorical pretreatment standards applies may, at its discretion and subject to the conditions of this section, grant removal credits to reflect removal by the POTW of pollutants specified in the categorical pretreatment standards. The POTW may grant a removal credit equal to or, at its discretion, less than its consistent removal rate. Upon being granted a removal credit, each affected industrial user shall calculate its revised discharge limits in accordance with subdivision 4 of this subsection. Removal credits may only be given for indicator or surrogate pollutants regulated in a categorical pretreatment standard if the categorical pretreatment statement so specifies.

3. Conditions for authorization to give removal credits. A POTW is authorized to give removal credits only if the following conditions are met;
a. Application. The POTW applies for, and receives, authorization from the director to give a removal credit in accordance with the requirements and procedures specified in subsection E of this section;

b. Consistent removal determination. The POTW demonstrates and continues to achieve consistent removal of the pollutant in accordance with subsection B of this section;

c. POTW local pretreatment program. The POTW has an approved pretreatment program in accordance with and to the extent required by this part; provided, however, a POTW which does not have an approved pretreatment program may, pending approval of such a program, conditionally give credits as provided in subsection D of this section;

d. Sludge requirements. The granting of removal credits will not cause the POTW to violate the local, state and federal sludge requirements which apply to the sludge management method chosen by the POTW. Alternatively, the POTW can demonstrate to the director that even though it is not presently in compliance with applicable sludge requirements, it will be in compliance when the industrial users to whom the removal credit would apply is required to meet its categorical pretreatment standards as modified by the removal credit. If granting removal credits forces a POTW to incur greater sludge management costs than would be incurred in the absence of granting removal costs, the additional sludge management costs will not be eligible for EPA grant assistance. Removal credits may be made available for the following pollutants:
(1) For any pollutant listed in Appendix G-I of the regulation incorporated by reference in 9VAC25-31-750 for the use or disposal practice employed by the POTW, when the requirements of Part VI of this chapter for that practice are met;

(2) For any pollutant listed in Appendix G-II of the regulation incorporated by reference in 9VAC25-31-750 for the use or disposal practice employed by the POTW when the concentration for a pollutant listed in Appendix G-II of the regulation incorporated by reference in 9VAC25-31-750 in the sewage sludge that is used or disposed does not exceed the concentration for the pollutant in Appendix G-II of the regulation incorporated by reference in 9VAC25-31-750; and

(3) For any pollutant in sewage sludge when the POTW disposes all of its sewage sludge in a municipal solid waste landfill that meets the criteria in the Code of Virginia and the Solid Waste Management Regulations, 9VAC20-81;

e. VPDES permit limitations. The granting of removal credits will not cause a violation of the POTW's permit limitations or conditions. Alternatively, the POTW can demonstrate to the director that even though it is not presently in compliance with applicable limitations and conditions in its VPDES permit, it will be in compliance when the industrial user or users to whom the removal credit would apply is required to meet its categorical pretreatment standard or standards, as modified by the removal credit provision.

4. Calculation of revised discharge limits. Revised discharge limits for a specific pollutant shall be derived by use of the following formula:

y = x
1 - r

where:

x = pollutant discharge limit specified in the applicable categorical pretreatment standard

r = removal credit for that pollutant as established under subsection B of this section (percentage removal expressed as a proportion, i.e., a number between 0 and 1)

y = revised discharge limit for the specified pollutant (expressed in same units as x)

B. Establishment of removal credits; demonstration of consistent removal.

1. Definition of "consistent removal." "Consistent removal" means the average of the lowest 50% of the removal measured according to subdivision 2 of this subsection. All sample data obtained for the measured pollutant during the time period prescribed in subdivision 2 of this subsection must be reported and used in computing consistent removal. If a substance is measurable in the influent but not in the effluent, the effluent level may be assumed to be the limit of measurement, and those data may be used by the POTW at its discretion and subject to approval by the director. If the substance is not measurable in the influent, the data may not be used. Where the number of samples with concentrations equal to or above the limit of measurement is between eight and 12, the average of the lowest six removals shall be used. If there are less than eight samples with concentrations equal to or above the limit of measurement, the director may approve alternate means for demonstrating consistent removal. The term "measurement" refers to the ability of the analytical method or protocol to quantify as well as identify the presence of the substance in question.

2. Consistent removal data. Influent and effluent operational data demonstrating consistent removal or other information, as provided for in subdivision 1 of this subsection, which demonstrates consistent removal of the pollutants for which discharge limit revisions are proposed. This data shall meet the following requirements:
a. Representative data; seasonal. The data shall be representative of yearly and seasonal conditions to which the POTW is subjected for each pollutant for which a discharge limit revision is proposed;

b. Representative data; quality and quantity. The data shall be representative of the quality and quantity of normal effluent and influent flow if such data can be obtained. If such data are unobtainable, alternate data or information may be presented for approval to demonstrate consistent removal as provided for in subdivision 1 of this subsection;

c. Sampling procedures: composite.
(1) The influent and effluent operational data shall be obtained through 24-hour flow-proportional composite samples. Sampling may be done manually or automatically, and discretely or continuously. For discrete sampling, at least 12 aliquots shall be composited. Discrete sampling may be flow-proportioned either by varying the time interval between each aliquot or the volume of each aliquot. All composites must be flow proportional to each stream flow at time of collection of influent aliquot or to the total influent flow since the previous influent aliquot. Volatile pollutant aliquots must be combined in the laboratory immediately before analysis.

(2)
(a) Twelve samples shall be taken at approximately equal intervals throughout one full year. Sampling must be evenly distributed over the days of the week so as to include no-workdays as well as workdays. If the director determines that this schedule will not be most representative of the actual operation of the POTW treatment plant, an alternative sampling schedule will be approved.

(b) In addition, upon the director's concurrence, a POTW may utilize an historical data base amassed prior to July 24, 1996, provide that such data otherwise meet the requirements of this paragraph. In order for the historical data base to be approved it must present a statistically valid description of daily, weekly and seasonal sewage treatment plant loadings and performance for at least one year.

(3) Effluent sample collection need not be delayed to compensate for hydraulic detention unless the POTW elects to include detention time compensation or unless the director requires detention time compensation. The director may require that each effluent sample be taken approximately one detention time later than the corresponding influent sample when failure to do so would result in an unrepresentative portrayal of actual POTW operation. The detention period is to be based on a 24-hour average daily flow value. The average daily flow used will be based upon the average of the daily flows during the same month of the previous year.

d. Sampling procedures: Grab. Where composite sampling is not an appropriate sampling technique, a grab sample or samples shall be taken to obtain influent and effluent operational data. Collection of influent grab samples should precede collection of effluent samples by approximately one detention period. The detention period is to be based on a 24-hour average daily flow value. The average daily flow used will be based upon the average of the daily flows during the same month of the previous year. Grab samples will be required, for example, where the parameters being evaluated are those, such as cyanide and phenol, which may not be held for any extended period because of biological, chemical or physical interactions which take place after sample collection and affect the results. A grab sample is an individual sample collected over a period of time not exceeding 15 minutes;

e. Analytical methods. The sampling referred to in subdivisions 2 a through d of this subsection and an analysis of these samples shall be performed in accordance with the techniques prescribed in 40 CFR Part 136 and amendments thereto. Where 40 CFR Part 136 does not contain sampling or analytical techniques for the pollutant in question, or where the administrator determines that the Part 136 sampling and analytical techniques are inappropriate for the pollutant in question, sampling and analysis shall be performed using validated analytical methods or any other applicable sampling and analytical procedures, including procedures suggested by the POTW or other parties, approved by the administrator; and

f. Calculation of removal. All data acquired under the provisions of this section must be submitted to the department. Removal for a specific pollutant shall be determined either, for each sample, by measuring the difference between the concentrations of the pollutant in the influent and effluent of the POTW and expressing the difference as a percentage of the influent concentration, or, where such data cannot be obtained, removal may be demonstrated using other data or procedures subject to concurrence by the director as provided for in subdivision 1 of this subsection.

C. Provisional credits. For pollutants which are not being discharged currently (i.e., new or modified facilities, or production changes) the POTW may apply for authorization to give removal credits prior to the initial discharge of the pollutant. Consistent removal shall be based provisionally on data from treatability studies or demonstrated removal at other treatment facilities where the quality and quantity of influent are similar. Within 18 months after the commencement of discharge of pollutants in question, consistent removal must be demonstrated pursuant to the requirements of subsection B of this section. If, within 18 months after the commencement of the discharge of the pollutant in question, the POTW cannot demonstrate consistent removal pursuant to the requirements of subsection B of this section, the authority to grant provisional removal credits shall be terminated by the director and all industrial users to whom the revised discharge limits had been applied shall achieve compliance with the applicable categorical pretreatment standards within a reasonable time, not to exceed the period of time prescribed in the applicable categorical pretreatment standards, as may be specified by the director.

D. Exception to POTW pretreatment program requirement. A POTW required to develop a local pretreatment program by 9VAC25-31-800 may conditionally give removal credits pending approval of such a program in accordance with the following terms and conditions:

1. All industrial users who are currently subject to a categorical pretreatment standard and who wish conditionally to receive a removal credit must submit to the POTW the information required in 9VAC25-31-840 B 1 through 7 (except new or modified industrial users must only submit the information required by 9VAC25-31-840 B 1 through 6), pertaining to the categorical pretreatment standard as modified by the removal credit. The industrial users shall indicate what additional technology, if any, will be needed to comply with the categorical pretreatment standard or standards as modified by the removal credit;

2. The POTW must have submitted to the department an application for pretreatment program approval meeting the requirements of 9VAC25-31-800 and 9VAC25-31-810 in a timely manner, not to exceed the time limitation set forth in a compliance schedule for development of a pretreatment program included in the POTW's VPDES permit, but in no case later than July 1, 1983, where no permit deadline exists;

3. The POTW must:
a. Compile and submit data demonstrating its consistent removal in accordance with subsection B of this section;

b. Comply with the conditions specified in subdivision A 3 of this section; and

c. Submit a complete application for removal credit authority in accordance with subsection E of this section;

4. If a POTW receives authority to grant conditional removal credits and the director subsequently makes a final determination, after appropriate notice, that the POTW failed to comply with the conditions in subdivisions 2 and 3 of this subsection, the authority to grant conditional removal credits shall be terminated by the director and all industrial users to whom the revised discharge limits had been applied shall achieve compliance with the applicable categorical pretreatment standards within a reasonable time, not to exceed the period of time prescribed in the applicable categorical pretreatment standards, as may be specified by the director;

5. If a POTW grants conditional removal credits and the POTW or the director subsequently makes a final determination, after appropriate notice, that the industrial user or users failed to comply with the conditions in subdivision 1 of this subsection, the conditional credit shall be terminated by the POTW or the director for the noncomplying industrial user or users and the industrial user or users to whom the revised discharge limits had been applied shall achieve compliance with the applicable categorical pretreatment standards within a reasonable time, not to exceed the period of time prescribed in the applicable categorical pretreatment standards, as may be specified by the director. The conditional credit shall not be terminated where a violation of the provisions of this paragraph results from causes entirely outside of the control of the industrial user or users or the industrial user or users had demonstrated subsequential compliance; and

6. The director may elect not to review an application for conditional removal credit authority upon receipt of such application, in which case the conditionally revised discharge limits will remain in effect until reviewed by the director. This review may occur at any time in accordance with the procedures of 9VAC25-31-830, but in no event later than the time of any pretreatment program approval or any VPDES permit reissuance thereunder.

E. POTW application for authorization to give removal credits and director review.

1. Who must apply. Any POTW that wants to give a removal credit must apply for authorization from the director.

2. To whom application is made. An application for authorization to give removal credits (or modify existing ones) shall be submitted by the POTW to the department.

3. When to apply. A POTW may apply for authorization to give or modify removal credits at any time.

4. Contents of the application. An application for authorization to give removal credits must be supported by the following information:
a. List of pollutants. A list of pollutants for which removal credits are proposed;

b. Consistent removal data. The data required pursuant to subsection B of this section;

c. Calculation of revised discharge limits. Proposed revised discharge limits for each affected subcategory of industrial users calculated in accordance with subdivision A 4 of this section;

d. Local pretreatment program certification. A certification that the POTW has an approved local pretreatment program or qualifies for the exception to this requirement found at subsection D of this section;

e. Sludge management certification. A specific description of the POTW's current methods of using or disposing of its sludge and a certification that the granting of removal credits will not cause a violation of the sludge requirements identified in subdivision A 3 d of this section; and

f. VPDES permit limit certification. A certification that the granting of removal credits will not cause a violation of the POTW's VPDES permit limits and conditions as required in subdivision A 3 e of this section.

5. Director review. The director shall review the POTW's application for authorization to give or modify removal credits in accordance with the procedures of 9VAC25-31-830 and shall, in no event, have more than 180 days from public notice of an application to complete review.

6. Nothing in this part precludes an industrial user or other interested party from assisting the POTW in preparing and presenting the information necessary to apply for authorization.

F. Continuation and withdrawal of authorization.

1. Effect of authorization. Once a POTW has received authorization to grant removal credits for a particular pollutant regulated in a categorical pretreatment standard it may automatically extend that removal credit to the same pollutant when it is regulated in other categorical standards, unless granting the removal credit will cause the POTW to violate the sludge requirements identified in subdivision A 3 d of this section or its VPDES permit limits and conditions as required by subdivision A 3 e of this section. If a POTW elects at a later time to extend removal credits to a certain categorical pretreatment standard, industrial subcategory or one or more industrial users that initially were not granted removal credits, it must notify the department.

2. Inclusion in POTW permit. Once authority is granted, the removal credits shall be included in the POTW's VPDES permit as soon as possible and shall become an enforceable requirement of the POTW's VPDES permit. The removal credits will remain in effect for the term of the POTW's VPDES permit, provided the POTW maintains compliance with the conditions specified in subdivision 4 of this subsection.

3. Compliance monitoring. Following authorization to give removal credits, a POTW shall continue to monitor and report on (at such intervals as may be specified by the director, but in no case less than once per year) the POTW's removal capabilities. A minimum of one representative sample per month during the reporting period is required, and all sampling data must be included in the POTW's compliance report.

4. Modification or withdrawal of removal credits.
a. Notice of POTW. The director shall notify the POTW if, on the basis of pollutant removal capability reports received pursuant to subdivision 3 of this subsection or other relevant information available to it, the director determines:
(1) That one or more of the discharge limit revisions made by the POTW, of the POTW itself, no longer meets the requirements of this section, or

(2) That such discharge limit revisions are causing a violation of any conditions or limits contained in the POTW's VPDES Permit.

b. Corrective action. If appropriate corrective action is not taken within a reasonable time, not to exceed 60 days unless the POTW or the affected industrial users demonstrate that a longer time period is reasonably necessary to undertake the appropriate corrective action, the director shall either withdraw such discharge limits or require modifications in the revised discharge limits.

c. Public notice of withdrawal or modification. The director shall not withdraw or modify revised discharge limits unless it shall first have notified the POTW and all industrial users to whom revised discharge limits have been applied, and made public, in writing, the reasons for such withdrawal or modification, and an opportunity is provided for a public hearing. Following such notice and withdrawal or modification, all industrial users to whom revised discharge limits had been applied, shall be subject to the modified discharge limits or the discharge limits prescribed in the applicable categorical pretreatment standards, as appropriate, and shall achieve compliance with such limits within a reasonable time (not to exceed the period of time prescribed in the applicable categorical pretreatment standards) as may be specified by the director.

G. Removal credits in state-run pretreatment programs. Where the director elects to implement a local pretreatment program in lieu of requiring the POTW to develop such a program the POTW will not be required to develop a pretreatment program as a precondition to obtaining authorization to give removal credits. The POTW will, however, be required to comply with the other conditions of subdivision A 3 of this section.

H. Compensation for overflow. For the purpose of this section, "overflow" means the intentional or unintentional diversion of flow from the POTW before the POTW treatment plant. POTWs which at least once annually overflow untreated wastewater to receiving waters may claim consistent removal of a pollutant only by complying with either subdivision 1 or 2 of this subsection. However, this subsection shall not apply where industrial users can demonstrate that overflow does not occur between the industrial users and the POTW treatment plant:

1. The industrial user provides containment or otherwise ceases or reduces discharges from the regulated processes which contain the pollutant for which an allowance is requested during all circumstances in which an overflow event can reasonably be expected to occur at the POTW or at a sewer to which the industrial user is connected. Discharges must cease or be reduced, or pretreatment must be increased, to the extent necessary to compensate for the removal not being provided by the POTW. Allowances under this provision will only be granted where the POTW submits to the department evidence that:
a. All industrial users to which the POTW proposes to apply this provision have demonstrated the ability to contain or otherwise cease or reduce, during circumstances in which an overflow event can reasonably be expected to occur, discharges from the regulated processes which contain pollutants for which an allowance is requested;

b. The POTW has identified circumstances in which an overflow event can reasonably be expected to occur, and has a notification or other viable plan to insure that industrial users will learn of an impending overflow in sufficient time to contain, cease or reduce discharging to prevent untreated overflows from occurring. The POTW must also demonstrate that it will monitor and verify the data required in subdivision 1 c of this subsection, to insure that industrial users are containing, ceasing or reducing operations during POTW system overflow; and

c. All industrial users to which the POTW proposes to apply this provision have demonstrated the ability and commitment to collect and make available, upon request by the POTW, the director or EPA Regional Administrator, daily flow reports or other data sufficient to demonstrate that all discharges from regulated processes containing the pollutant for which the allowance is requested were contained, reduced or otherwise ceased, as appropriate, during all circumstances in which an overflow event was reasonably expected to occur; or

2.
a. The consistent removal claimed is reduced pursuant to the following equation:

rc = rm 8760 - z
8760

where:

rm = POTW's consistent removal rate for that pollutant as established under subsections A 1 and B 2 of this section

rc = removal corrected by the overflow factor

Z = hours per year that overflow occurred between the industrial user or users and the POTW treatment plant, the hours either to be shown in the POTW's current VPDES permit application or the hours, as demonstrated by verifiable techniques, that a particular industrial user's discharge overflows between the industrial user and the POTW treatment plant.

b. The POTW is complying with all VPDES permit requirements and any additional requirements in any order or decree, issued pursuant to the Clean Water Act affecting combined sewer outflows. These requirements include, but are not limited to, any combined sewer overflow requirements that conform to the Combined Sewer Overflow Control Policy.

Statutory Authority

§ 62.1-44.15 of the Code of Virginia; § 402 of the federal Clean Water Act; 40 CFR Parts 122, 123, 124, 403, and 503.

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