Source: http://lis.virginia.gov/cgi-bin/legp604.exe?000+reg+9VAC25-31-790
Timestamp: 2019-04-21 16:57:44+00:00

Document:
"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.
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.
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.
(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.
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.
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.
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.
(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.
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.
Derived from Virginia Register Volume 12, Issue 20, eff. July 24, 1996; amended, Virginia Register Volume 18, Issue 9, eff. February 15, 2002; Volume 22, Issue 24, eff. September 6, 2006; Volume 27, Issue 26, eff. September 28, 2011; Volume 28, Issue 10, eff. February 15, 2012.

References: § 405
 § 6901
 § 6901
 § 4701
 § 2601
 § 1401