Vol. 36 Iss. 12 - February 03, 2020

Chapter 401
Final Regulation

REGISTRAR'S NOTICE: The State Water Control Board is claiming an exemption from Article 2 of the Administrative Process Act in accordance with § 2.2-4006 A 3, which excludes regulations that consist only of changes in style or form or corrections of technical errors. The State Water Control Board will receive, consider, and respond to petitions by any interested person at any time with respect to reconsideration or revision.

Title of Regulation: 9VAC25-401. Sewage Treatment in the Dulles Area Watershed (amending 9VAC25-401-30, 9VAC25-401-40).

Statutory Authority: § 62.1-44.15 of the Code of Virginia.

Effective Date: March 4, 2020.

Agency Contact: Melissa Porterfield, Department of Environmental Quality, 1111 East Main Street, Suite 1400, P.O. Box 1105, Richmond, VA 23218, telephone (803) 698-4238, or email

Small Business Impact Review Report of Findings: This final regulatory action serves as the report of the findings of the regulatory review pursuant to § 2.2-4007.1 of the Code of Virginia.


The amendments correct a cross reference to another Virginia Administrative Code section and a typographical error in the regulation.

9VAC25-401-30. Sewage treatment plant restrictions and requirements.

A. The number of sewage treatment plants discharging effluent to surface waters identified in 9VAC25-401-20 shall be no more than two, one to be under the authority of the Town of Leesburg and one under the authority of Loudoun County. The discharge from the treatment plants shall be in the Broad Run and Goose Creek Watersheds a minimum of 10 stream miles upstream from the Fairfax County Water Authority water supply intake on the Potomac River.

B. The following maximum effluent limitations shall apply for the sewage treatment plants prescribed in subsection A of this section:


Monthly Average


10.0 mg/l


1.0 mg/l


1.0 mg/l

Total PhosphousPhosphorus

0.1 mg/l


0.5 NTU

E. coli

 less than 2 per 100 ml

The above parameters and all other pollutants shall also be monitored and limited as necessary in accordance with the VPDES Permit Regulation.

The owners of the sewage treatment plants are responsible for knowing nitrate concentrations in the vicinity of Fairfax County Water Authority's intake on the Potomac River. Should nitrate concentrations at the intake reach 5 mg/l, the owners shall evaluate measures they can take to minimize impacts their discharge has on the nitrate concentrations and implement those measures deemed feasible and effective.

C. Requirements for sewage treatment plants in subsection A of this section.

1. The design shall be such that expansions and maintenance of any unit can be accomplished without bypassing wastes to the receiving waters and without degrading treatment.

2. The mechanical and fluid system design shall be such that a single failure of a component or unit shall not interrupt plant operations that are required to meet the final effluent requirements in subsection B of this section.

3. There shall be one independent source of outside power supply and one on-site power supply. Both the off-site and on-site electrical distributions shall be such that the failure of any one given component (mechanical or electrical) in the distribution system shall not cause an interruption of electrical service to parts of the plant that are essential to meet the effluent requirements.

4. The treatment plants shall be staffed 24 hours a day, seven days a week.

D. Design requirements for pumping stations for sewage treatment plants in subsection A of this section. Pumping stations on all sewage collection systems that are connected to the plants identified in subsection A of this section shall meet the Reliability Classification 1 requirements as described in the Virginia Sewage Collection and Treatment Regulations (9VAC25-790), and shall have retention basins with a minimum of one-day capacity. A waiver from the retention basin requirement may be obtained from the Department of Environmental Quality if the owner of the pump station can demonstrate that a sewer system tributary to the pump station meets the infiltration/inflow infiltration or inflow criteria established by the Virginia Sewage Collection and Treatment Regulations, and any other such information that the department may require.

9VAC25-401-40. Exceptions.

The following exceptions to 9VAC25-401-30 A may be allowed on a case-by-case basis after review and approval by the Department of Environmental Quality:

1. Existing sewage treatment plants. Existing sewage treatment plants located in the affected waters and not authorized by 9VAC25-400-30 9VAC25-401-30 A may continue to discharge to surface waters provided they were constructed prior to January 1975. Such discharges may continue only as long as the Department of Environmental Quality determines that it is not feasible for them to connect to a publicly owned sewage treatment plant. Expansions of these treatment works may be allowed as long as pollutant quantities or loadings are not increased.

2. Failing septic systems. Existing residential homes, industrial and commercial operations, public facilities, and any other operation where a septic drain field system has failed may discharge treated sewage effluent provided that the applicant demonstrates that it is not feasible to connect to a publicly owned sewage treatment plant and that there is no feasible alternative except to discharge. Discharge permits shall be issued in conformance with the State Water Control Law, the Virginia VPDES Permit Regulation (9VAC25-31), and the Water Quality Standards (9VAC25-260).

VA.R. Doc. No. R20-5983; Filed January 6, 2020, 2:46 p.m.