5 Colo. Code Regs. § 1002-64.12

Current through Register Vol. 47, No. 11, June 10, 2024

Section 5 CCR 1002-64.12 - CLASSIFICATION AND USE OF BIOSOLIDS

A.Metals Based Classification of Biosolids.

(1) Criteria for metals based classification of biosolids shall be as defined in Table 1 and Table 3. Determination of compliance with Table 1 or Table 3 criteria shall be demonstrated by analysis of the final product material for all of the parameters identified in Table 1 and Table 3. Biosolids classified as Table 1 - Ceiling Concentration Limits -are subject to the Cumulative Pollutant Loading Rates outlined in Table 2 below:

Table 1 - Ceiling Concentration Limits

Pollutant	mg/kg, dry weight basis
Arsenic	75
Cadmium	85
Copper	4300
Lead	840
Mercury	57
Molybdenum	75
Nickel	420
Selenium	100¹
Zinc	7500

Table 2 - Cumulative Pollutant Loading Rates

Pollutant	kg/ha (lbs/ac)
Arsenic	41 (37)
Cadmium	39 (35)
Copper	1500 (1339)
Lead	300 (286)
Mercury	17 (17)
Molybdenum
Nickel	420 (375)
Selenium	100 (89)
Zinc	2800 (2499)

Table 3 - Pollutant Concentration Limits

Pollutant	mg/kg, dry weight basis
Arsenic	41
Cadmium	39
Copper	1500
Lead	300
Mercury	17
Molybdenum
Nickel	420
Selenium	100
Zinc	2800

¹ As a result of a ruling by the United States Court of Appeals for the District of Columbia Circuit on March 3, 1998, the selenium limit set forth in Table 1 is stayed with respect to the City of Pueblo's land application of biosolids at public contact sites with low potential for child occupancy.

(2) Biosolids which exceed the numeric criteria for Table 1 biosolids shall not be applied to land for beneficial use except as may be allowed pursuant to the Colorado Solid Waste Disposal Sites and Facilities Regulations.

(3) Compliance with the numeric criteria contained in Table 1 or Table 3 shall be determined as follows:

(a) The arithmetic average of all samples collected within a given calendar month and analyzed for a given parameter shall not exceed the numeric limit for Table 3 biosolids for any parameter if the biosolids are to be considered to be within Table 3 Pollutant Concentration Limits (PC).

(b) The concentration for any given parameter for which criteria are identified shall not exceed the numeric limit for Table 1 biosolids in any sample if the biosolids are to be considered below Table 1 Ceiling Concentration Limits.

(c) The initial determination of biosolids grade shall be as demonstrated by the arithmetic average of no less than three composite biosolids samples.

(d) For reclassification of Table 1 quality as Table 3 quality biosolids compliance with the Table 3 criteria shall be demonstrated by the arithmetic average of no less than seven daily composite biosolids samples.

(e) For reclassification of biosolids which had previously exceeded the Table 1 numeric criteria, compliance with the Table 1 criteria shall be demonstrated by the arithmetic average of no less than seven daily composite biosolids samples.

(f) All sampling of biosolids for the purpose of demonstrating compliance with the criteria contained in Table 1 or Table 3 shall be performed in accordance with the requirements of section 64.16(A)(6).

(g) If at any time the arithmetic average of all samples collected within a given calendar month and analyzed for a given parameter exceeds the Table 3 Pollutant Concentration Limits, the biosolids shall no longer be considered within Table 3 Limits and all applicable requirements for Table 1 biosolids, or the requirements of paragraph 64.12(A)(2) shall apply. Reclassification of such biosolids shall be in accordance with the requirements of 64.12(A)(3)(d) above.

(h) If at any time the concentration for any given parameter for which numeric criteria are identified exceeds the Table 1 Ceiling Concentration Limits, the biosolids shall no longer be considered within Table 1 limits and the requirements of paragraph 64.12(A)(2) shall apply. Reclassification of such biosolids shall be in accordance with the requirements of 64.12(A)(3)(e) above.

B.Pathogen Destruction Criteria.

(1) The requirement in paragraph (2) of this section and the requirements of any one of paragraphs (3) through (7) of this section shall be met for biosolids to be classified as Class A with respect to pathogens.

(2) The Class A pathogen requirements in paragraphs (3) through (7) shall be met either prior to meeting or at the same time the vector attraction reduction requirements in section 64.12 are met, except in those instances when the vector attraction reduction requirements in paragraphs 64.12(C)(11) through 64.12(C)(13), are those which are met.

(3) Class A - Alternative 1

(a) Either the density of fecal coliform in the biosolids shall be less than 1000 Most Probable Number per gram of total solids (dry weight basis), or the density of Salmonella sp. bacteria in the biosolids shall be less than three Most Probable Number per four grams of total solids (dry weight basis) at the time the biosolids are used or distributed; or at the time the final product material derived from biosolids is prepared to meet the requirements in section 64.14 of these regulations, and

(b) The temperature of the biosolids that is used or distributed shall be maintained at a specific value for a period of time as determined using the following procedures:

(i) When the percent solids of the biosolids is seven percent or higher, the temperature of the biosolids shall be 50 degrees Celsius or higher; the time period shall be 20 minutes or longer; and the temperature and time period shall be determined using the following equation, except when small particles of biosolids are heated by either warmed gases or an immiscible liquid.

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(ii) When the percent solids of the biosolids is seven percent or higher and small particles of biosolids are heated by either warmed gases or an immiscible liquid, the temperature of the biosolids shall be 50 degrees Celsius or higher; the time period shall be 15 seconds or longer; and the temperature and time period shall be determined using the equation specified in paragraph (3)(b)(i) of this section.

(iii) When the percent solids of the biosolids is less than seven percent and the time period is at least 15 seconds, but less than 30 minutes, the temperature and time period shall be determined using the equation specified in paragraph (3)(b)(i)f this section.

(iv) When the percent solids of the biosolids is less than seven percent; the temperature of the biosolids is 50 degrees Celsius or higher; and the time period is 30 minutes or longer, the temperature and time period shall be determined using the following equation:

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(4) Class A - Alternative 2

(b) at the time the final product material derived from biosolids is prepared to meet the requirements in section 64.14 of these regulations

(i) the pH of the biosolids that is used or distributed shall be raised to above 12 s.u. and shall remain above 12 s.u. for 72 hours, and

(ii) the temperature of the biosolids shall be above 52 degrees Celsius for 12 hours or longer during the period that the pH of the biosolids is above 12 s.u., and

(iii) at the end of the 72-hour period during which the pH of the biosolids is above 12 s.u., the biosolids shall be air dried to achieve a percent solids in the biosolids of greater than 50 percent.

(5) Class A - Alternative 3

(a) Either the density of fecal coliform in the biosolids shall be less than 1000 Most Probable Number per gram of total solids (dry weight basis), or the density of Salmonella sp. bacteria in biosolids shall be less than three Most Probable Number per four grams of total solids (dry weight basis), at the time the biosolids are used or distributed; or at the time the final product material derived from biosolids is prepared to meet the requirements in section 64.14 of these regulations, and

(b) the biosolids shall be analyzed prior to pathogen treatment to determine whether the biosolids contains enteric viruses.

(i) When the density of enteric viruses in the biosolids prior to pathogen treatment is less than one Plaque-forming Unit per four grams of total solids (dry weight basis), the biosolids is considered Class A with respect to enteric viruses until the next monitoring episode for the biosolids.

(ii) When the density of enteric viruses in the biosolids prior to pathogen treatment is equal to or greater than one Plaque-forming Unit per four grams of total solids (dry weight basis), the biosolids is considered Class A with respect to enteric viruses when the density of enteric viruses in the biosolids after pathogen treatment is less than one Plaque-forming Unit per four grams of total solids (dry weight basis) and when the values or ranges of values for the operating parameters for the pathogen treatment process that produces the biosolids that meets the enteric virus density requirement are documented.

(iii) After the enteric virus reduction in paragraph (ii) of this subsection is demonstrated for the pathogen treatment process, the biosolids continues to be considered Class A with respect to enteric viruses when the values for the pathogen treatment process operating parameters are consistent with the values or ranges of values documented in paragraph (ii) of this subsection.

(c) The biosolids shall be analyzed prior to pathogen treatment to determine whether the sewage sludge contains viable helminth ova.

(i) When the density of viable helminth ova in the biosolids prior to pathogen treatment is less than one per four grams of total solids (dry weight basis), the biosolids is considered Class A with respect to viable helminth ova until the next monitoring episode for the biosolids.

(ii) When the density of viable helminth ova in the biosolids prior to pathogen treatment is equal to or greater than one per four grams of total solids (dry weight basis), the biosolids is considered Class A with respect to viable helminth ova when the density of viable helminth ova in the biosolids after pathogen treatment is less than one per four grams of total solids (dry weight basis) and when the values or ranges of values for the operating parameters for the pathogen treatment process that produces the biosolids that meets the viable helminth ova density requirement are documented.

(iii) After the viable helminth ova reduction in paragraph (ii) of this subsection is demonstrated for the pathogen treatment process, the biosolids continue to be considered Class A with respect to viable helminth ova when the values for the pathogen treatment process operating parameters are consistent with the values or ranges of values documented in (ii) of this subsection.

(6) Class A - Alternative 4

(a) Either the density of fecal coliform in the biosolids shall be less than 1000 Most Probable Number per gram of total solids (dry weight basis) or the density of Salmonella sp. bacteria in the biosolids shall be less than three Most Probable Number per four grams of total solids (dry weight basis) at the time the biosolids are used or distributed; or at the time the final product material derived from biosolids is prepared to meet the requirements in section 64.14 of these regulations, and

(i) The density of enteric viruses in the biosolids shall be less than one Plaque-forming Unit per four grams of total solids (dry weight basis) at the time the biosolids are used or distributed; or at the time the final product material derived from biosolids is prepared to meet the requirements in section 64.14 of these regulations, and

(ii) the density of viable helminth ova in the biosolids shall be less than one per four grams of total solids (dry weight basis) at the time the biosolids are used or distributed; or at the time the final product material derived from biosolids is prepared to meet the requirements in section 64.14 of these regulations.

(7) Class A - Alternative 5

(a) Either the density of fecal coliform in the biosolids shall be less than 1000 Most Probable Number per gram of total solids (dry weight basis) or the density of Salmonella, sp. bacteria in the biosolids shall be less than three Most Probable Number per four grams of total solids (dry weight basis) at the time the biosolids are used or distributed; or at the time the final product material derived from biosolids is prepared to meet the requirements in section 64.14 of these regulations, and

(b) Biosolids that are used or distributed shall be treated in one of the Processes to Further Reduce Pathogens described as follows:

(i) Composting - Using either the within-vessel composting method or the static aerated pile composting method, the temperature of the biosolids compost is maintained at 55 degrees Celsius or higher for three days.

Using the windrow composting method, the temperature of the biosolids compost is maintained at 55 degrees or higher for 15 days or longer. During the period when the compost is maintained at 55 degrees or higher, there shall be a minimum of five turnings of the windrow.

(ii) Heat drying - Biosolids are dried by direct or indirect contact with hot gases to reduce the moisture content of the biosolids to 10 percent or lower. Either the temperature of the biosolids particles exceeds 80 degrees Celsius or the wet bulb temperature of the gas in contact with the biosolids as the biosolids leaves the dryer exceeds 80 degrees Celsius.

(iii) Heat treatment - Liquid biosolids are heated to a temperature of 180 degrees Celsius or higher for 30 minutes.

(iv) Thermophilic aerobic digestion - Liquid biosolids are agitated with air or oxygen to maintain aerobic conditions and the mean cell residence time of the biosolids is 10 days at 55 to 60 degrees Celsius.

(v) Beta ray irradiation - Biosolids are irradiated with beta rays from an accelerator at dosages of at least 1.0 megarad at room temperature (ca. 20 degrees Celsius).

(vi) Gamma ray irradiation - Biosolids are irradiated with gamma rays from certain isotopes, such as Cobalt 60 and Cesium 137, at room temperature (ca. 20 degrees Celsius).

(vii) Pasteurization - The temperature of the biosolids is maintained at 70 degrees Celsius or higher for 30 minutes or longer.

(viii) Any other method of biosolids treatment which is certified as a Process to Further Reduce Pathogens by the U. S. Environmental Protection Agency, Region VIII, or, after assumption of delegation by the State, which is certified as such by the Division.

(8) The requirement in either of paragraphs (a), or (b) of this subsection shall be met for biosolids to be classified as Class B with respect to pathogens.

(a) Seven individual samples of the biosolids shall be collected at the time the biosolids are used or distributed or at the time the final product material derived from biosolids is prepared to meet the requirements in section 64.15 of these regulations. The geometric mean of the density of fecal coliform in the samples collected shall be less than either 2,000,000 Most Probable Number per gram of total solids (dry weight basis) or 2,000,000 Colony Forming Units per gram of total solids (dry weight basis), or

(b) Biosolids that are used or distributed shall be treated in one of the Processes to Significantly Reduce Pathogens described as follows:

(i) Aerobic digestion - Biosolids are agitated with air or oxygen to maintain aerobic conditions for a mean cell residence time at a temperature or temperatures within a time-temperature function having as end points 40 days at 20 degrees Celsius and no less than 60 days at 15 degrees Celsius.

(ii) Air drying - Biosolids are dried on sand beds or on paved or unpaved basins. The biosolids dries for a minimum of three months. During two of the three months, the ambient average daily temperature is above zero degrees Celsius.

(iii) Anaerobic digestion - Biosolids are treated in the absence of air for a mean cell residence time at a temperature or temperatures within a time-temperature function having as end points 15 days at 35 to 55 degrees Celsius and no less than 60 days at 20 degrees Celsius.

(iv) Composting - Using either the within-vessel, static aerated pile, or windrow composting methods, the temperature of the biosolids is raised to 40 degrees Celsius or higher and remains at 40 degrees Celsius or higher for five days. For four hours during the five days, the temperature in the compost pile exceeds 55 degrees Celsius.

(v) Lime stabilization - Sufficient lime is added to the biosolids to raise the pH of the sewage sludge to 12 after two hours of contact.

(vi) Any other method of biosolids treatment which is certified as a Process to Significantly Reduce Pathogens by the U. S. Environmental Protection Agency, Region VIII, or, after assumption of delegation by the State, which is certified as such by the Division.

(9) The site restrictions in section 64.15 of these regulations shall be met when biosolids that meets the Class B pathogen requirements in paragraphs (8)(a) or (8)(b) of this subsection is applied to the land.

C.Vector Attraction Reduction (Biosolids Stability) Criteria.

(1) One of the biosolids stability requirements in paragraphs (3) through (13) shall be met when biosolids are applied to agricultural or disturbed land, or to a public contact site.

(2) One of the biosolids stability requirements in paragraphs (3) through (10) shall be met when biosolids are distributed to the public for use.

(3) The mass of volatile solids in the biosolids shall be reduced by a minimum of 38 percent.

(4) When the 38 percent volatile solids reduction requirement in paragraph (3) cannot be met for anaerobically digested biosolids, biosolids stability can be demonstrated by digesting a portion of the previously digested biosolids anaerobically in the laboratory in a bench-scale unit for 40 additional days at a temperature between 30 and 37 degrees Celsius. When at the end of the 40 days, the volatile solids in the biosolids at the beginning of that period is reduced by less than 17 percent, biosolids stability is achieved.

(5) When the 38 percent volatile solids reduction requirement in paragraph (3) cannot be met for aerobically digested biosolids, biosolids stability can be demonstrated by digesting a portion of the previously digested biosolids that has a percent solids of two percent or less aerobically in the laboratory in a bench-scale unit for 30 additional days at 20 degrees Celsius. When at the end of the 30 days, the volatile solids in the biosolids at the beginning of that period is reduced by less than 15 percent, biosolids stability is achieved.

(6) The specific oxygen uptake rate (SOUR) for biosolids 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 degrees Celsius.

(7) Biosolids shall be treated in an aerobic process for 14 days or longer. During that time, the temperature of the biosolids shall be higher than 40 degrees Celsius and the average temperature of the biosolids shall be higher than 45 degrees Celsius.

(8) The pH of biosolids 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.

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

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

(11) Biosolids shall be subsurface injected, and

(a) No significant amount of the biosolids shall be present on the land surface within one hour after the biosolids are injected.

(b) When the biosolids which are subsurface injected are considered to be Class A with respect to pathogens, the biosolids shall be injected within eight hours after being discharged from the pathogen treatment process.

(12) Biosolids which are surface applied shall be incorporated into the soil within six hours after application to or placement on the land.

(13) When biosolids that are incorporated into the soil are considered to be Class A with respect to pathogens, the biosolids shall be applied to or placed on the land within eight hours after being discharged from the pathogen treatment process.

5 CCR 1002-64.12

44 CR 17, September 10, 2021, effective 9/30/2021