9VAC25-31-540. Pollutant limits.

A. Biosolids.

1. Bulk biosolids or biosolids sold or given away in a bag or other container shall not be applied to the land if the concentration of any pollutant in the biosolids exceeds the ceiling concentration for the pollutant in Table 1 of this section.

2. If bulk biosolids is applied to agricultural land, forest, a public contact site, or a reclamation site, either:

a. The cumulative loading rate for each pollutant shall not exceed the cumulative pollutant loading rate for the pollutant in Table 2 of this section; or

b. The concentration of each pollutant in the biosolids shall not exceed the concentration for the pollutant in Table 3 of this section.

3. If bulk biosolids is applied to a lawn or a home garden, the concentration of each pollutant in the biosolids shall not exceed the concentration for the pollutant in Table 3 of this section.

4. If biosolids is sold or given away in a bag or other container for application to the land, either:

a. The concentration of each pollutant in the biosolids shall not exceed the concentration for the pollutant in Table 3 of this section; or

b. The product of the concentration of each pollutant in the biosolids and the annual whole sludge application rate for the biosolids shall not cause the annual pollutant loading rate for the pollutant in Table 4 of this section to be exceeded. The procedure used to determine the annual whole sludge application rate is presented in subsection D of this section.

B. Pollutant concentrations and loading rates - biosolids.

TABLE 1 CEILING CONCENTRATIONS
Pollutant	Ceiling Concentration (milligrams per kilogram)*
Arsenic	75
Cadmium	85
Copper	4,300
Lead	840
Mercury	57
Molybdenum	75
Nickel	420
Selenium	100
Zinc	7,500
*Dry weight basis

TABLE 2 CUMULATIVE POLLUTANT LOADING RATES⁽¹⁾
Pollutant	Cumulative Pollutant Loading Rate
Pollutant	(kilograms per hectare)	(pounds per acre)
Arsenic⁽²⁾	41	36
Cadmium	39	35
Copper	1,500	1,340
Lead	300	270
Mercury	17	16
Molybdenum⁽²⁾
Nickel	420	375
Selenium	100	89
Zinc	2,800	2,500
Notes: ⁽¹⁾Such total applications to be made on soils with the biosolids/soil mixture pH adjusted to 6.0 or greater if the biosolids cadmium content is greater than or equal to 21 mg/kg. The maximum cumulative application rate is limited for all ranges of cation exchange capacity due to soil background pH in Virginia of less than 6.5 and lack of regulatory controls of soil pH adjustment after biosolids application ceases. ⁽²⁾The maximum cumulative application rate is currently under study by the USEPA. Research suggests that for Molybdenum a cumulative pollutant loading rate below 40 kg/hectare may be appropriate to reduce the risk of copper deficiency in grazing animals.

TABLE 3 POLLUTANT CONCENTRATIONS
Pollutant	Monthly Average Concentration (milligrams per kilogram)*
Arsenic	41
Cadmium	39
Copper	1,500
Lead	300
Mercury	17
Molybdenum⁽¹⁾
Nickel	420
Selenium	100
Zinc	2,800
*Dry weight basis Note: ⁽¹⁾The monthly average concentration is currently under study by the USEPA. Research suggests that a monthly average Molybdenum concentration below 40 mg/kg may be appropriate to reduce the risk of copper deficiency in grazing animals.

TABLE 4 ANNUAL POLLUTANT LOADING RATES
Pollutant	Annual Pollutant Loading Rate⁽¹⁾ (per 365-day period)
Pollutant	(kilograms per hectare)	(pounds per acre)
Arsenic	2.0	1.8
Cadmium	1.9	1.7
Copper	75	67
Lead	15	13
Mercury	0.85	0.76
Molybdenum⁽²⁾
Nickel	21	19
Selenium	5.0	4.6
Zinc	140	125
Notes: ⁽¹⁾Such total applications to be made on soils with the biosolids/soils mixture pH adjusted to 6.0 or greater if the biosolids cadmium content is greater than or equal to 21 mg/kg. The maximum cumulative application rate is limited for all ranges of cation exchange capacity due to soil pH in Virginia of less than 6.5 and lack of regulatory controls of soil pH adjustment after biosolids application ceases. ⁽²⁾The maximum cumulative application rate is currently under study by the USEPA.

C. Domestic septage. The annual application rate for domestic septage applied to agricultural land, forest, or a reclamation site shall not exceed the annual application rate calculated using equation (1).

EQUATION (1)

AAR = N/0.0026

AAR = Annual application rate in gallons per acre per 365-day period.

N = Amount of nitrogen in pounds per acre per 365-day period needed by the crop or vegetation grown on the land.

D. Procedures to determine the annual whole sludge application rate for biosolids. 9VAC25-31-540 A 4 b requires that the product of the concentration for each pollutant listed in Table 4 of this section in biosolids sold or given away in a bag or other container for application to the land and the AWSAR for the biosolids not cause the annual pollutant loading rate for the pollutant in Table 4 to be exceeded. This section contains the procedure used to determine the AWSAR for a biosolids that does not cause the annual pollutant loading rates in Table 4 of this section to be exceeded.

1. The relationship between the APLR for a pollutant and the AWSAR for a biosolids is shown in equation (2).

EQUATION (2)

APLR = C x AWSAR x 0.001

APLR = Annual pollutant loading rate in kilograms per hectare per 365-day period

C = Pollutant concentration in milligrams per kilogram of total solids (dry weight basis)

AWSAR = Annual whole sludge application rate in metric tons per hectare per 365-day period (dry weight basis)

0.001 = A conversion factor

2. To determine the AWSAR, equation (2) is rearranged into equation (3):

EQUATION (3)
AWSAR = APLR/(C x 0.001)
AWSAR = Annual whole sludge application rate in metric tons per hectare per 365-day period (dry weight basis)
APLR = Annual pollutant loading rate in kilograms per hectare per 365-day period
C = Pollutant concentration in milligrams per kilogram of total solids (dry weight basis)
0.001 = A conversion factor

3. The procedure used to determine the AWSAR for a biosolids is presented below.

a. Analyze a sample of the biosolids to determine the concentration for each of the pollutants listed in Table 4 of this section in the biosolids.

b. Using the pollutant concentrations from Step 1 and the APLRs from Table 4 of this section, calculate an AWSAR for each pollutant using equation (3) above.

c. The AWSAR for the biosolids is the lowest AWSAR calculated in Step 2.

Statutory Authority

§ 62.1-44.15 of the Code of Virginia.

Historical Notes

Derived from Virginia Register Volume 12, Issue 20, eff. July 24, 1996; amended, Virginia Register Volume 29, Issue 24, eff. September 1, 2013.

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