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Virginia Administrative Code
Title 12. Health
Agency 5. Department of Health
Chapter 610. Sewage Handling and Disposal Regulations

12VAC5-610-1080. Anaerobic Lagooning of Septage.

Article 9
Special Facilities

A. General. An anaerobic lagoon for the purpose of this chapter is a nondischarging facility consisting of an open impervious structure, constructed of earth or other material specifically designed for receiving and stabilizing septage and other sewage sludges. Industrial waste sludges and sludges containing toxic material shall not be placed in these lagoons.

B. General site requirements.

1. Engineering, geologic, soil and hydrologic evaluation. Geologic information required by the district or local health department and the division shall include, but not be limited to, soil characteristics, percolation information, maximum ground water table, direction of ground water movement and permeability.

2. Location.

a. Minimum setback distances for topographic features are the same as those for subsurface soil absorption systems and are contained in Table 4.2.

b. Buffer zone. Buffer zone criteria are contained in Appendix I.

c. Flood protection. The anaerobic lagoon and operational components shall be located at an elevation which is not subject to the 100-year flood/wave action or shall otherwise be adequately protected against the 100-year flood/wave action damage. The anaerobic lagoon shall remain fully operational during the 25-year flood/wave action.

d. Surface runoff. Adequate provisions shall be made to divert storm water around the anaerobic lagoon and otherwise protect the lagoon's embankments.

3. Access. An all weather access road shall be provided.

4. Fencing. The facility site to include treatment units and appurtenances shall be fenced with a five foot fence (woven wire plus barbed wire); gates and locks to provide controlled entry into the facility. The fence shall be posted with signs identifying the facility, safety and health dangers and trespass penalties. The fence shall not be constructed closer than 10 feet to the outside edge of any treatment unit or appurtenance.

C. Design requirements (see Figure V-1 for typical sections).

1. Receiving facilities.

a. An impervious pad or sufficient strength to support a loaded tank truck and with drainage to the lagoon shall be provided at the point or points where the contents of the tank truck is offloaded into the lagoon or receiving facilities.

b. The receiving and inlet facilities shall be designed to transport the septage into the lagoon, to distribute the septage as evenly as possible throughout the lagoon and to minimize generation of odors and suspension of solids.

2. Treatment units.

a. Anaerobic lagoons.

(1) Number and capacity. A minimum of two lagoons shall be provided. The combined total capacity of the lagoons shall provide eight months storage based on the average daily discharge into the lagoon.

(2) Operating depth. The normal operating depth shall be from three to five feet.

(3) Lagoon bottom. The lagoon bottom shall be level, constructed of impervious material (10%686 sm/sec) and be a minimum of two feet above the seasonal water table or at the original ground surface.

(4) Lagoon embankments. Embankments and/or dike walls shall be impervious and structurally stable. They shall be designed to permit access of equipment by appropriate lining or internal barriers necessary for sludge removal in a nuisance free and safe manner, and to minimize risk, supervision, operation and maintenance. Earthen embankments shall be sloped (minimum 1:3) and seeded with proper cover, subject to soil characteristics, to minimize erosion.

(5) Freeboard. A minimum freeboard of two feet above the normal depth shall be provided.

(6) Shape. A uniform shape shall be provided, i.e., round, square, or rectangular with no narrow or elongated portions. The lagoon shall not contain islands, peninsulas or coves unless they are part of the inlet/outlet design.

b. Sludge dewatering. When sludge dewatering units are provided they shall be designed in accordance with 12VAC5-580-700, Sludge Dewatering, Virginia Sewerage Regulations.

3. Supernatant disposal. Normally the lagoon supernatant should be included in the sludge mixed liquor which is disposed of on the land. When a system is designed to provide for separate supplemental supernatant disposal it shall be by subsurface soil absorption system. The minimum subsurface soil absorption system field size shall be based on the anticipated average daily supernatant generation rate and shall meet all applicable criteria contained in Article 1 (12VAC5-610-450 et seq.) of Part III and Article 5 (12VAC5-610-900) of this part. The lagoon outlet shall be designed to minimize the solids content of the supernatant withdrawn for disposal in the subsurface soil absorption system and shall be provided with a means to control the rate and quantity of supernatant withdrawal.


For Anaerobic lagooning of septage, see Virginia Administrative Code print product.

Statutory Authority

§§ 32.1-12 and 32.1-164 of the Code of Virginia.

Historical Notes

Derived from VR355-34-02 § 4.43, eff. February 5, 1986; amended, eff. May 11, 1988; Volume 16, Issue 16, eff. July 1, 2000.

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