Wisconsin Administrative Code
Department of Natural Resources
NR 700-799 - Environmental Protection - Investigation and Remediation of Environmental Contamination
Chapter NR 720 - Soil cleanup standards
Section NR 720.12 - Procedures for determining residual contaminant levels based on protection of human health from direct contact with contaminated soil

Universal Citation: WI Admin Code § NR 720.12

Current through August 26, 2024

(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.

Note: The department will generally consider toxicological values in the following order: U.S. EPA's Integrated Risk Information System (IRIS); U.S. EPA's Provisional Peer Reviewed Toxicity Values (PPRTV); Agency for Toxic Substances and Disease Registry (ATSDR); California EPA (Cal EPA); U.S. EPA's Health Effects Assessment Summary Tables (HEAST); other pertinent toxicological information.

(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 cm2 with a skin-soil adherence factor of 0.2 mg/cm2 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 x109 m3/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 cm2 with a skin-soil adherence factor of 0.2 mg/cm2 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 x109 m3/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 cm2 with a skin-soil adherence factor of 0.2 mg/cm2, and an adult's daily exposed skin-surface area of 5,700 cm2 with a skin-soil adherence factor of 0.07 mg/cm2 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 x109 m3/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.

d. An averaging period of 25 years of exposure shall be assumed during a 70 year lifetime.

Note: EPA's regional screening level user's guide provides a table containing contaminant specific dermal absorption factors and soil to air volatilization factors. The document can be found at: http://www.epa.gov/reg3hwmd/risk/human/rb-concentration_table/usersguide.htm.

Note: Department approval of alternative exposure assumptions for a site or facility may be based on consultation with the department of health services. If EPA makes changes to the default exposure assumptions, the department would generally use the revised values.

Note: Guidance document RR-890 provides detailed instructions on one method the department considers scientifically valid for purposes of calculating site specific residual contaminant levels that are protective of the direct contact pathway. A table of residual contaminant levels that are calculated using the standard default exposure assumptions can be found at: http://dnr.wi.gov/topic/Brownfields/professionals.html#tabx2.

(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/cm3.

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/cm3.

6. A soil organic carbon content of 0.006.

(b) For soil to groundwater:

1. A dry soil bulk density of 1.5 gm/cm3.

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/cm3.

6. A soil organic carbon content of 0.002.

These soil parameter values are the defaults used in Pub-RR-890, "Soil Residual Contaminant Level Determination Using the US EPA Regional Screening Level Web Calculator." This guidance may be found at http://dnr.wi.gov/topic/Brownfields/Pubs.html.

Disclaimer: These regulations may not be the most recent version. Wisconsin may have more current or accurate information. We make no warranties or guarantees about the accuracy, completeness, or adequacy of the information contained on this site or the information linked to on the state site. Please check official sources.

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