Virginia Administrative Code
Title 9 - ENVIRONMENT
Agency 25 - STATE WATER CONTROL BOARD
Chapter 31 - VIRGINIA POLLUTANT DISCHARGE ELIMINATION SYSTEM (VPDES) PERMIT REGULATION
Part VI - Standards for the Use of Biosolids or Disposal of Sewage Sludge
Article 4 - Pathogens and Vector Attraction Reduction
Section 9VAC25-31-720 - Vector attraction reduction

1. One of the vector attraction reduction requirements in subdivisions B 1 through B 10 of this section shall be met when bulk biosolids is applied to agricultural land, forest, a public contact site, or a reclamation site.

2. One of the vector attraction reduction requirements in subdivisions B 1 through B 8 of this section shall be met when bulk biosolids is applied to a lawn or a home garden.

3. One of the vector attraction reduction requirements in subdivisions B 1 through B 8 of this section shall be met when biosolids is sold or given away in a bag or other container for application to the land.

4. One of the vector attraction reduction requirements in subdivisions B 1 through B 11 of this section shall be met when sewage sludge (other than domestic septage) is placed on an active sewage sludge unit.

5. One of the vector attraction reduction requirements in subdivision B 9, B 10, or B 12 of this section shall be met when domestic septage is applied to agricultural land, forest, or a reclamation site and one of the vector attraction reduction requirements in subdivisions B 9 through B 12 of this section shall be met when domestic septage is placed on an active sewage sludge unit.

1. The mass of volatile solids in the sewage sludge shall be reduced by a minimum of 38%, calculated according to the method in 9VAC25-31-490 B 8.

2. When the 38% volatile solids reduction requirement in subdivision 1 of this subsection cannot be met for an anaerobically digested sewage sludge, vector attraction reduction can be demonstrated by digesting a portion of the previously digested sewage sludge anaerobically in the laboratory in a bench-scale unit for 40 additional days at a temperature between 30°C and 37°C. When at the end of the 40 days, the volatile solids in the sewage sludge at the beginning of that period is reduced by less than 17%, vector attraction reduction is achieved.

3. When the 38% volatile solids reduction requirement in subdivision 1 of this section cannot be met for an aerobically digested sewage sludge, vector attraction reduction can be demonstrated by digesting a portion of the previously digested sewage sludge that has a percent solids of 2.0% or less aerobically in the laboratory in a bench-scale unit for 30 additional days at 20°C. When at the end of the 30 days, the volatile solids in the sewage sludge at the beginning of that period is reduced by less than 15%, vector attraction reduction is achieved.

4. The specific oxygen uptake rate (SOUR) for sewage sludge treated in an aerobic process shall be equal to or less than 1.5 milligrams of oxygen per hour per gram of total solids (dry weight basis) at a temperature of 20°C.

5. Sewage sludge shall be treated in an aerobic process for 14 days or longer. During that time, the temperature of the sewage sludge shall be higher than 40°C and the average temperature of the sewage sludge shall be higher than 45°C.

6. The pH of sewage sludge shall be raised to 12 or higher by alkaline addition and, without the addition of more alkaline material, shall remain at 12 or higher for two hours and then at 11.5 or higher for an additional 22 hours.

7. The percent solids of sewage sludge that does not contain unstabilized solids generated in a primary wastewater treatment process shall be equal to or greater than 75% based on the moisture content and total solids prior to mixing with other materials.

8. The percent solids of sewage sludge that contains unstabilized solids generated in a primary wastewater treatment process shall be equal to or greater than 90% based on the moisture content and total solids prior to mixing with other materials.

9. Sewage sludge injection requirements:

10. Sewage sludge incorporation requirements:

11. Sewage sludge placed on an active sewage sludge unit shall be covered with soil or other material at the end of each operating day.

12. The pH of domestic septage shall be raised to 12 or higher by alkaline addition and, without the addition of more alkaline material, shall remain at 12 or higher for 30 minutes.