Procedures for determining residual contaminant levels based on protection of human health from direct contact with contaminated soil

Procedures for determining residual contaminant levels based on protection of human health from direct contact with contaminated soil. (1) General. If a responsible party selects this option, residual contaminant levels for soil based on protection of human health from direct contact shall be developed using the following criteria: (a) For individual compounds using an excess cancer risk of 1x10 -6 and a hazard quotient for non-carcinogens of one; and (b) The cumulative excess cancer risk will not exceed 1x10 -5 and the hazard index for non-carcinogens will not exceed one for the site or facility. (c) Risks for carcinogens and hazard quotients for non-carcinogens are presumed to be additive within each category, unless there is specific information that demonstrates that an alternative approach is more appropriate. (d) If toxicological values for both carcinogenic and non-carcinogenic end points exist for a substance, both shall be evaluated and the method that generates the lowest residual contaminant level shall be used for the site or facility. (2) Methods and procedures. Responsible parties shall determine a residual contaminant level to protect public health from direct contact with soil contamination using scientifically valid procedures and toxicological values approved by the department and the default exposure assumptions identified in sub. (3) or alternative assumptions specifically approved by the department in writing. (3) Default exposure assumptions. (a) Non-carcinogens. When the contaminant is not a carcinogen, the following default exposure assumptions shall be used: 1. When the land use of a site or facility is classified as non-industrial, in accordance with s. NR 720.05 (5) , all of the following shall apply: a. Incidental ingestion of soil shall be assumed to occur at the rate of 200 mg of soil per day for a 15 kg child for 350 days each year. b. Dermal absorption of soil shall be determined assuming a child’s daily exposed skin surface area of 2,800 cm 2 with a skin-soil adherence factor of 0.2 mg/cm 2 and a contaminant specific dermal absorption fraction. c. Inhalation of outdoor soil vapors shall be assumed to occur for each volatile contaminant at a 24-hour daily exposure rate determined by the volatile’s soil-to-air volatilization factor, and inhalation of particulate matter shall be determined assuming a particulate emission factor of 1.43 x10 9 m 3 /kg. d. An averaging period for exposure shall equal the default exposure duration of 6 years. 2. When the land use of a site or facility is classified as industrial, in accordance with s. NR 720.05 (5) , all of the following shall apply: a. Incidental ingestion of soil shall be assumed to occur at the rate of 100 mg of soil per day for a 70 kg adult worker for 250 days each year. b. Dermal absorption of soil shall be determined assuming an adult outdoor worker’s daily exposed skin surface of 3,300 cm 2 with a skin-soil adherence factor of 0.2 mg/cm 2 and a contaminant specific dermal absorption fraction. c. Inhalation of outdoor soil vapors shall be assumed to occur for each volatile contaminant at an 8-hour daily exposure rate determined by the volatile contaminant’s soil-to-air volatilization factor, and inhalation of particulate matter shall be determined assuming a particulate emission factor of 1.43 x10 9 m 3 /kg. d. An averaging period of exposure shall equal the default exposure duration of 25 years. (b) Carcinogens. When the contaminant is a carcinogen, the following default exposure assumptions shall be used: 1. When the land use of a site or facility is classified as non-industrial, in accordance with s. NR 720.05 (5) , all of the following shall apply: a. Incidental ingestion of soil shall be assumed to occur at the rate of 200 mg of soil per day for 350 days each year for 6 years for a 15 kg child and the rate of 100 mg per day for 350 days each year for 24 years for a 70 kg adult. b. Dermal absorption of soil shall be determined assuming a child’s daily exposed skin surface area of 2,800 cm 2 with a skin-soil adherence factor of 0.2 mg/cm 2 , and an adult’s daily exposed skin-surface area of 5,700 cm 2 with a skin-soil adherence factor of 0.07 mg/cm 2 and a contaminant specific dermal absorption fraction. c. Inhalation of outdoor soil vapors shall be assumed to occur for each volatile contaminant at a 24-hour daily exposure rate determined by the volatile contaminant’s soil-to-air volatilization factor, and inhalation of particulate matter shall be determined assuming a particulate emission factor of 1.43 x10 9 m 3 /kg. For mutagenic contaminants, age segmented exposure durations shall be assumed when age adjusted cancer slope factors are available. d. An averaging period of 30 years of exposure consisting of 6 child years and 24 adult years shall be assumed during a 70 year lifetime. 2. When the land use of a site or facility is classified as industrial, in accordance with s. NR 720.05 (5) , all of the following shall apply: a. Incidental ingestion of soil shall be assumed to occur at the rate of 100 mg of soil per day for 250 days each year for a 70 kg adult worker. b. Dermal absorption of soil shall be determined assuming an adult outdoor worker’s daily exposed skin surface of 3,300 cm 2 with a skin-soil adherence factor of 0.2 mg/cm 2 and a contaminant specific dermal absorption fraction. c. Inhalation of outdoor soil vapors shall be assumed to occur for each volatile contaminant at an 8-hour daily exposure rate determined by the volatile contaminant’s soil-to-air volatilization factor, and inhalation of particulate matter shall be determined assuming a particulate emission factor of 1.43 x10 9 m 3 /kg. d. An averaging period of 25 years of exposure shall be assumed during a 70 year lifetime. (4) Soil parameter values. Unless otherwise approved, when determining site specific residual contaminant levels, all the following soil parameter values shall be used: (a) For direct contact: 1. A dry soil bulk density of 1.5 gm/cm 3 . 2. An air filled soil porosity of 0.28. 3. A total soil porosity of 0.43. 4. A water filled porosity of 0.15. 5. A soil particle density of 2.65 gm/cm 3 . 6. A soil organic carbon content of 0.006. (b) For soil to groundwater: 1. A dry soil bulk density of 1.5 gm/cm 3 . 2. An air filled soil porosity of 0.13. 3. A total soil porosity of 0.43. 4. A water filled porosity of 0.30. 5. A soil particle density of 2.65 gm/cm 3 . 6. A soil organic carbon content of 0.002.