Section 470. Calculating state permit conditions

A. State permit effluent limitations, monitoring requirements, standards and prohibitions shall be established for each outfall or discharge point of the permitted facility, except as otherwise provided under 9VAC25-870-460.

B. All state permit effluent limitations, standards, or prohibitions for a metal shall be expressed in terms of total recoverable metal as defined in 40 CFR Part 136 unless:

1. An applicable effluent standard or limitation has been promulgated under the CWA and specifies the limitation for the metal in the dissolved or valent or total form; or

2. In establishing state permit limitations on a case-by-case basis under 40 CFR 125.3, it is necessary to express the limitation on the metal in the dissolved or valent or total form to carry out the provisions of the CWA, Stormwater Management Act and the State Water Control Law; or

3. All approved analytical methods for the metal inherently measure only its dissolved form (e.g., hexavalent chromium).

C. Discharges that are not continuous, as defined in 9VAC25-870-10, shall be particularly described and limited, considering the following factors, as appropriate:

1. Frequency;

2. Total mass;

3. Maximum rate of discharge of pollutants during the discharge; and

4. Prohibition or limitation of specified pollutants by mass, concentration, or other appropriate measure.

D. Mass Limitations.

1. All pollutants limited in state permits shall have limitations, standards or prohibitions expressed in terms of mass except:

a. For pH, temperature, radiation, or other pollutants that cannot appropriately be expressed by mass;

b. When applicable standards and limitations are expressed in terms of other units of measurement; or

c. If in establishing technology-based state permit limitations on a case-by-case basis, limitations expressed in terms of mass are infeasible because the mass of the pollutant discharged cannot be related to a measure of operation (for example, discharges of TSS from certain mining operations), and state permit conditions ensure that dilution will not be used as a substitute for treatment.

2. Pollutants limited in terms of mass additionally may be limited in terms of other units of measurement, and the state permit shall require the state permittee to comply with both limitations.

Historical Notes

Former 4VAC50-60-470 derived from Volume 21, Issue 03, eff. January 29, 2005; amended, Volume 29, Issue 04, eff. November 21, 2012; amended and renumbered, Virginia Register Volume 30, Issue 02, eff. October 23, 2013.

Statutory Authority

§§ 62.1-44.15:25 and 62.1-44.15:28 of the Code of Virginia.