Chapter 415. Policy for the Potomac River Embayments
9VAC25-415-10. Purpose.
This chapter provides for the control of point source discharges into the Virginia embayment waters of the Potomac River from the fall line at Chain Bridge in Arlington County to the Route 301 Bridge in King George County.
This chapter also constitutes Special Standard "b' in the State Water Control Board's Water Quality Standards "Special Standards and Requirements" (9VAC25-260-310) for the Potomac River Basin's Potomac River Subbasin (9VAC25-260-400).
Statutory Authority
§ 62.1-44.15 of the Code of Virginia.
Historical Notes
Derived from Virginia Register Volume 13, Issue 12, eff. April 2, 1997.
9VAC25-415-20. Affected waters.
This chapter shall apply to all embayments and their tidal and nontidal tributaries, including their headwaters, of the Potomac River, from the fall line at Chain Bridge in Arlington County to the Route 301 Bridge in King George County. The Occoquan River watershed, upstream of the fall line at the Occoquan Dam, shall not be subject to the terms of this chapter, since those waters are governed by the Occoquan Policy (9VAC25-410-10 et seq.).
Statutory Authority
§ 62.1-44.15 of the Code of Virginia.
Historical Notes
Derived from Virginia Register Volume 13, Issue 12, eff. April 2, 1997.
9VAC25-415-30. Policy requirements.
A. Existing discharges shall meet the requirements of 9VAC25-415-40 within five years from April 2, 1997, unless exempted under subsection B, C or D of this section. New dischargers shall meet the requirements of 9VAC25-415-40 immediately.
B. Existing discharges with design flows less than 0.05 mgd shall be exempt from meeting the requirements of 9VAC25-415-40 until the completion of their next design flow expansion.
C. Failing septic systems. Existing residential homes, industrial and commercial operations, public facilities, and any other operation where a septic drain field system has failed shall be exempt from the requirements of 9VAC25-415-40, provided that the applicant demonstrates that it is not feasible to connect to a publicly-owned treatment plant and that there is no feasible alternative except to discharge. Discharge permits shall be issued in conformance with the Virginia Pollutant Discharge Elimination System (VPDES) Permit Regulation (9VAC25-31) and Virginia Pollutant Discharge Elimination System (VPDES) General Permit for Domestic Sewage Discharges of Less Than or Equal to 1,000 Gallons Per Day (9VAC25-110).
D. Other exemptions. The requirements of 9VAC25-415-40 shall not apply to the following types of discharges: combined sewer overflows, stormwater, corrective action remediation, and industrial discharges where BOD and nutrients are not primary pollutants of concern.
Statutory Authority
§ 62.1-44.15 of the Code of Virginia.
Historical Notes
Derived from Virginia Register Volume 13, Issue 12, eff. April 2, 1997; amended, Virginia Register Volume 37, Issue 15, eff. April 14, 2021.
9VAC25-415-40. Effluent limitations.
The following effluent limitations shall apply to all sewage treatment plants:
| Parameter | Monthly Avg (mg/l) |
| CBOD5 | 5 |
| Total Suspended Solids | 6 |
| Total Phosphorus | 0.18 |
| NH3 (Apr 1 - Oct 31) | 1 |
The above limitations shall not replace or exclude the discharge from meeting the requirements of the state's Water Quality Standards (9VAC25-260-10 et seq.).
Statutory Authority
§ 62.1-44.15 of the Code of Virginia.
Historical Notes
Derived from Virginia Register Volume 13, Issue 12, eff. April 2, 1997.
9VAC25-415-50. Water quality modeling.
Water quality models may be required to predict the effect of wastewater discharges on the water quality of the receiving waterbody, the embayment, and the Potomac River. The purpose of the modeling shall be to determine if more stringent limits than those required in 9VAC25-415-40 are required to meet water quality standards. If modeling demonstrates the necessity for more restrictive limits, the more restrictive limits shall apply. Where needed, modeling shall account for and address previous modeling exercises and shall include all relevant point and nonpoint sources. All models shall undergo a peer review process. The models and modeling results shall be considered during the public participation process to ensure proper public input into the modeling process. The models shall be documented and certified by the Virginia Department of Environmental Quality for use in preparing VPDES permits for discharges to the Potomac Embayments and the Potomac River. All changes and modifications to the models shall receive peer review and be appropriately documented. Documentation on the models shall include the basis and reasoning for the recommended models including inputs and assumptions. The rationale shall be described in nontechnical language so someone who is reasonably familiar with water pollution problems can understand the inputs and the reasons behind them.
Statutory Authority
§ 62.1-44.15 of the Code of Virginia.
Historical Notes
Derived from Virginia Register Volume 13, Issue 12, eff. April 2, 1997.
9VAC25-415-60. Administrative review.
Within three years after the effective date of this chapter, the department shall perform an analysis on this chapter and provide the board with a report on the results. The analysis shall include (i) the purpose and need for the chapter, (ii) alternatives which would achieve the stated purpose of this chapter in a less burdensome and less intrusive manner, (iii) an assessment of the effectiveness of this chapter, (iv) the results of a review of current state and federal statutory and regulatory requirements, including identification and justification of requirements of this chapter which are more stringent than federal requirements, and (v) the results of a review as to whether this chapter is clearly written and easily understandable by affected entities.
Upon review of the department's analysis, the board shall confirm the need to (i) continue this chapter without amendment, (ii) repeal this chapter, or (iii) amend this chapter. If the board's decision is to repeal or amend this chapter, the board shall authorize the department to initiate the applicable regulatory process to carry out the decision of the board.
Statutory Authority
§ 62.1-44.15 of the Code of Virginia.
Historical Notes
Derived from Virginia Register Volume 13, Issue 12, eff. April 2, 1997.