Title 18 . Environmental Conservation

Chapter 75 . Administrative Enforcement

Section 341. Soil cleanup levels; tables

18 AAC 75.341. Soil cleanup levels; tables

(a) If a responsible person uses method one for a non-Arctic zone under 18 AAC 75.340, the soil cleanup levels must be based on Table A1 in this subsection.

TABLE A1. METHOD ONE - PETROLEUM HYDROCARBON SOIL CLEANUP LEVELS IN NONARCTIC (See notes to table for further requirements) Part A: Determine score for each item* 1. Depth to Groundwater Less than 5 feet (10) 5 feet to 15 feet (8) More than 15 feet to 25 feet (6) More than 25 feet to 50 feet (4) More than 50 feet (1) 2. Mean Annual Precipitation More than 40 inches (10) More than 25 inches to 40 inches (5) 15 inches to 25 inches (3) Less than 15 inches (1) 3. Soil Type (Unified Soil Classification) Clean, course-grained soils (10) Coarse-grained soils with fines (8) Fine-grained soils (low organic carbon) (3) Fine-grained soils (high organic carbon) (1) 4. Potential Receptors (Select the most applicable category) a. Public water system within 1000 feet, or private water system within 500 feet (15) b. Public/private water system within 1 /2 mile (12) c. Public/private water system within one mile (8) d. No water system within one mile (4) e. Nonpotable groundwater (1) 5. Volume of Contaminated Soil More than 500 cubic yards (10) More than 100 cubic yards to 500 cubic yards (8) More than 25 cubic yards to 100 cubic yards (5) 10 cubic yards to 25 cubic yards (2) Less than 10 cubic yards (0)

*The items to be scored are defined in note 1 to this table.

Part B: Add scores from Part A to determine matrix score and cleanup level

Cleanup Level in mg/kg Gasoline Diesel Residual Matrix Score for Range Range Range Each Category Organics Organics Organics Category A: More 50 100 2000 than 40 Category B: 26 - 40 100 200 2000 Category C: 21 - 26 500 1000 2000 Category D: Less 1000 2000 2000 than 21

Notes to Table Al:

1. The following definitions for items 1 - 5 in Part A apply for purposes of using method one:

a. "depth to groundwater" means the measurement from the lowest point of the zone of soil contamination to the seasonal high groundwater table; a responsible person may not claim a lower matrix score for soil by moving contaminated soil to a higher elevation relative to the groundwater table;

b. "mean annual precipitation" is defined at 18 AAC 75.990;

c. "soil type" means the predominant Unified Soil Classification (USC) soil type between the deepest point of contamination and the seasonal high groundwater table; a responsible person may seek to demonstrate that otherwise coarse-grained soil has an organic carbon content that might enable a lower point classification. Soil types using the USC system are further defined as shown in Figure 1:

Figure 1 UNIFIED SOILS CLASSIFICATIONS Clean coarse-grained GW, GP, SW, SP Coarse-grained with fines GM, GC, SM, SC, GP-GC, SP-SM, GW-GM, SW-SM, SW-SC Fine-grained with low organic carbon ML, CL, HM, CH Fine-grained with high organic carbon OL, OH, Pt

d. for the "potential receptors" categories,

(i) "public water system" and "private water system" have the meaning given those terms in 18 AAC 80.1990;

(ii) "nonpotable" means unusable for drinking water due to a water quality condition, such as salinity, that was not caused by or that does not arise from contamination at the site;

e. "volume of contaminated soil" means the total estimated volume of soil that is contaminated above the applicable cleanup level before a responsible person begins a removal or cleanup action.

2. For the "potential receptors" categories, a responsible person shall submit a demonstration supporting the score assigned, including the results of an approved water well survey; the most conservative score must be used to determine the proximity of potential receptors; for example, if a water system is within one-quarter mile, the category, "public/private water system within one mile" that would score 8 would be superseded by the category "public/private water system within 1/2 mile" that would score 12.

3. The identity of a released refined petroleum product must be assumed to be unknown unless a responsible person demonstrates that the product is only gasoline, or only a refined nongasoline product; the department will waive the requirement that a product be identified by analysis if a responsible person demonstrates that only one type of product was stored or distributed at the site; the soil cleanup levels in Part B are based on gas chromatographic analytical measurements corresponding to a specific measured range of petroleum hydrocarbons as follows:

a. gasoline range organics: light-range petroleum products such as gasoline, with petroleum hydrocarbon compounds corresponding to an alkane range from the beginning of C6 to the beginning of C10 and a boiling point range between approximately 60ΓΈ Centigrade and 170ΓΈ Centigrade;

b. diesel range organics: mid-range petroleum products such as diesel fuel, with petroleum hydrocarbon compounds corresponding to an alkane range from the beginning of C10 to the beginning of C25 and a boiling point range between approximately 170ΓΈ Centigrade and 400ΓΈ Centigrade;

c. residual range organics: heavy-range petroleum products such a lubricating oils, with petroleum hydrocarbon compounds corresponding to an alkane range from the beginning of C25 to the beginning of C36 and a boiling point range between approximately 400ΓΈ Centigrade and 500ΓΈ Centigrade.

4. In addition to meeting the soil cleanup levels in Part B, a responsible person shall ensure that the site meets the most stringent standards for benzene, toluene, ethlbenzene, and total xylenes for the applicable exposure pathway in Table B1 in (c) of this section.

(b) If a responsible person uses method one for an Arctic zone under 18 AAC 75.340, the soil cleanup levels must be based on Table A2 in this subsection.

TABLE A2. METHOD ONE - PETROLEUM HYDROCARBON SOIL CLEANUP LEVELS IN THE ARCTIC Cleanup Level in mg/kg Product Diesel Gasoline Residual Range Range Range Petroleum Petroleum Petroleum Hydrocarbons Hydrocarbons Hydrocarbons Gasoline N/A 100 N/A Diesel 200* N/A N/A Unknown/Crude 200 100 N/A Residual N/A N/A 2000

In this table, "N/A" means "not applicable."

*If a responsible party demonstrates that contamination is due to a diesel spill, that levels of benzene, toluene, ethylbenzene, and total xylene isomers (BTEX) are less than 15 mg/kg, that benzene levels are less than 0.5 mg/kg, and that other site conditions are favorable, and if the department determines that a less stringent level is protective of human health, safety, and welfare, and of the environment, the department will allow a cleanup level of 500 mg/kg for diesel range petroleum hydrocarbons.

The Arctic Zone numeric cleanup levels in this table cover only contamination related to manmade pads and roads. The department will determine the cleanup levels for undisturbed tundra or other undisturbed native vegetation on a site-specific basis, depending upon whether a cleanup action would cause more severe or long-term damage than would the discharge or release alone.

(c) If a responsible person uses method two for chemicals other than petroleum hydrocarbons under 18 AAC 75.340, the soil cleanup levels must be based on Table B1 in this subsection.

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NOTES TO TABLE B1 FOLLOW TABLE B2 IN (d) OF THIS SECTION

(d) If a responsible person uses method two for petroleum hydrocarbons under 18 AAC 75.340, the soil cleanup levels must be based on Table B2 in this subsection.

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Notes to Tables B1 and B2:

For PCB-free mineral oils, the department will approve alternate levels or exposure pathways, if the department determines that the alternative levels or exposure pathways are protective of human health, safety, and welfare, and of the environment. Although migration to groundwater is not applicable to the Arctic zone, site-specific levels must be protective of migration to surface water. Concentrations of hazardous substances in soil must be calculated and presented on a per dry weight basis. For volatile organic hazardous substances for which toxicity data is not currently available, the cleanup level that applies at a site is the calculated saturation concentration determined using the equations set out in Cleanup Levels Guidance, adopted by reference in 18 AAC 75.340. The cleanup level from Table B1 or B2 that applies at a site is the most stringent of the applicable exposure pathway-specific cleanup levels based on ingestion, inhalation, or migration to groundwater. In Table B1, a blank space means not available or not applicable.

1. "Arctic zone" is defined at 18 AAC 75.990.

2. "under 40 inch zone" means a site that receives mean annual precipitation of less than 40 inches each year.

3. "over 40 inch zone" means a site that receives mean annual precipitation of 40 or more inches each year.

4. "CAS Number" means the Chemical Abstract Service (CAS) registry number uniquely assigned to chemicals by the American Chemical Society and recorded in the CAS Registry System.

5. "ingestion" means a potential pathway of exposure to hazardous substances in soil through direct consumption of the soil.

6. "inhalation" means a potential pathway of exposure to volatile organic hazardous substances in the soil through volatilization.

7. "migration to groundwater" means a potential exposure to hazardous substances in soil through direct ingestion of groundwater contaminated with concentrations of hazardous substances at levels listed in Table C at 18 AAC 75.345(b) (1) as a result of movement of hazardous substances through soil to the groundwater; this exposure pathway is not applicable to the Arctic zone, where soil cleanup levels protective of migration to surface water must be determined on a site-specific basis.

8. Dioxin cleanup levels must be determined on a site-specific basis.

9. For unrestricted land use, PCBs in soil shall be cleaned up to one mg/kg or less, unless the department determines that a different cleanup level is necessary as provided in 18 AAC 75.340(i) , as, for example, in a subsistence food gathering area. With the prior approval of the department, PCBs in soil may be cleaned up to

(A) between 1 and 10 mg/kg if the responsible person

(i) caps each area containing PCBs in soil at levels between 1 and 10 mg/kg; for purposes of this Note 9, "caps" means covering an area of PCB contaminated soil with an appropriate material to prevent exposure of humans and the environment to PCBs; to be approved, a cap must be designed and constructed of a material acceptable to the department and of sufficient strength and durability to withstand the use of the surface that is exposed to the environment; within 72 hours after discovery of a breach to the integrity of a cap, the responsible person or the landowner shall initiate repairs to that breach; and

(ii) provides the department within 60 days after completing the cleanup, documentation that the responsible person has recorded a deed notation in the appropriate land records, or on another instrument that is normally examined during a title search, documenting that PCBs remain in the soil, that the contaminated soil has been capped, and that subsequent interest holders may have legal obligations with respect to the cap and the contaminated soil; or

(B) an alternative PCB soil cleanup level developed through an approved site-specific risk assessment, conducted according to the Risk Assessment Procedures Manual, adopted by reference at 18 AAC 75.340.

10. Cyanide expressed as free, or physiologically available cyanide.

11. Lead cleanup levels must be determined on a site-specific basis, based on land use. For residential land use, the soil cleanup level is 400 mg/kg. For commercial or industrial land use, as applied in 18 AAC 75.340(e) (3), the soil cleanup level is 1,000 mg/kg. Through an approved site-specific risk assessment, conducted according to the Risk Assessment Procedures Manual, adopted by reference at 18 AAC 75.340, approved exposure models may be used to evaluate exposure to a child resident or an adult worker. A responsible person may also propose an alternative cleanup level, through a site-specific risk assessment conducted according to the Manual, and based on a chemical speciation of the lead present at the site. For soils contaminated with lead more than 15 feet below ground surface, lead cleanup levels will be determined on a site-specific basis.

12. These levels are based on soil saturation level (Csat) using the equations set out in Cleanup Levels Guidance, adopted by reference in 18 AAC 74.340.

13. Ingestion value is adjusted by a factor of 0.5 to account for dermal exposure.

14. This level is the concentration of C6 -C10, C10-C25, or C25-C36 petroleum hydrocarbon range in surface and subsurface soil that, if exceeded, indicates an increased potential for hazardous substance migration or for risk to human health, safety, or welfare, or to the environment; the level of a petroleum hydrocarbon may not remain at a concentration above the maximum allowable concentration unless a responsible person demonstrates that the petroleum hydrocarbon will not migrate and will not pose a significant risk to human health, safety, or welfare, or to the environment. Free product must be recovered as required by 18 AAC 75.325(f) .

15. If using method two or method three, the applicable petroleum hydrocarbon cleanup levels must be met in addition to the applicable chemical-specific cleanup levels for benzene, ethylbenzene, toluene, and total xylenes; the chemical-specific cleanup levels for the polynuclear aromatic hydrocarbons acenaphthene, anthracene, benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene, chrysene, dibenzo(a,h)anthracene, fluorene, indeno(1,2,3-c,d)pyrene, naphthalene, and pyrene must also be met unless the department determines that those cleanup levels need not be met to protect human health, safety, and welfare, and the environment.

History: Eff. 1/22/99, Register 149; am 8/27/2000, Register 155; am 1/30/2003, Register 165

Authority: AS 46.03.020

AS 46.03.050

AS 46.03.710

AS 46.03.740

AS 46.03.745

AS 46.04.020

AS 46.04.070

AS 46.09.020

Editor's note: The applicable EPA rule governing disposal and cleanup of PCB contaminated facilities under 40 C.F.R. Part 761.61 (PCB remediation waste) may apply to PCB cleanup at a contaminated site. The PCB cleanup levels listed in Table B1 are based on cleanup levels referred to in 40 C.F.R. 761.61 for high occupancy areas with no cap.