1. (a) If a responsible person uses method one for petroleum hydrocarbons 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 ZONES (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 Matrix Score for Each Category Cleanup Level in mg/kg Gasoline Range Organics Diesel Range Organics Residual Range Organics Category A: More501002000than 40Category B: 26 - 401002002000Category C: 21 - 2650010002000Category D: Less100020002000than 21 Notes to Table A1: 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 SOIL TYPE UNIFIED SOILS CLASSIFICATIONS Clean coarse-grainedGW, GP, SW, SPCoarse-grained with finesGM, GC, SM, SC, GP-GC, SP- SM, GW-GM, SW-SM, SW-SCFine-grained with low organic carbonML, CL, HM, CHFine-grained with high organic carbonOL, 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 60° Centigrade and 170° 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 170° Centigrade and 400° 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 400° Centigrade and 500° 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, ethylbenzene, and total xylenes for the applicable exposure pathway in Table B1 in (c) of this section.
2. (b) If a responsible person uses method one for petroleum hydrocarbons 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 ZONE PRODUCT Cleanup Level in mg/kg Diesel Range Petroleum Hydro- carbons Gasoline Range Petroleum Hydro- carbons Residual Range Petroleum Hydro- carbons GasolineN/A100N/ADiesel200*N/AN/AUnknown/Crude200100N/AResidualN/AN/A2000In 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.
3. (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. TABLE B1. METHOD TWO - SOIL CLEANUP LEVELS TABLE (See notes for additional requirements) Hazardous SubstanceCAS Num- ber1health effect that drives risk; carcin-ogen (ca); noncar-cinogen (nc); muta-gen (m)Arctic Zone2 Under 40 Inch Zone3 Over 40 Inch Zone4 Migration to Ground- water6 (mg/kg)Human Health5 (mg/kg)Human Health5 (mg/kg)Human Health5 (mg/kg)Acenaphthene 783-32-9nc630046003800 37 Acenaphthylene7.8208-96-8nc310023001900 18 Acetone67-64-1nc1.0 x 105;9 8100065000 38 Aldrin309-00-2ca0.670.490.40 0.0099 Anthracene7120-12-7nc310002300019000 390 Antimony (metallic)7440-36-0nc5541334.6 Arsenic, lnorganic117440-38-2ca128.87.20.20 Barium7440-39-3nc2500020000170002100 Benz[a]anthracene756-55-3m2014120.70 Benzaldehyde100-52-7nc770 (3000)10 770 (2300)10 770 (1800)10 0.52 Benzene771-43-2ca16118.10.022 Benzo[a]pyrene750-32-8m2.01.51.21.9 Benzo[b]fluoranthene7205-99-2m20151220 Benzo[g,h,i]perylene7.8191-24-2nc31002300190015000 Benzo[k]fluoranthene7207-08-9m200150120190 Bcnzoic Acid65-85-0nc1.0 x 105;9 1.0 x 105;9 1.0 x 105;9 200 Benzyl Alcohol100-51-6nc11000820067005.7 Beryllium and compounds7440-41-7nc270200170260 Bis(2-chloroethyl)ether111-44-4ca4.02.82.10.00042 Bis(2-ethylhexyl)phthalate117-81-7ca68050041088 Bromobenzene108-86-1nc160 (410)10 160 (290)10 160 (215)10 0.36 Bromodichloromethane75-27-4ca5.33.62.60.0043 Bromoform75-25-2ca3402401700.10 Bromomethane74-83-9nc15107.40.024 Butadiene, 1,3-106-99-0ca1.20.860.640.0012 Butanol, N-71-36-3nc6500 (14000)10 6500 (10000)10 6500 (8300)10 5.3 Butyl Benzyl Phthalate85-68-7ca50003700300016 Butylbenzene, n-104-51-8nc20 (6800)10 20 (5000)10 20 (4150)10 23 Butylbenzene, sec-135-98-8nc28 (14000)10 28 (10000)10 28 (8300)10 42 Butylbenzene, tert-98-06-6nc36 (14000)10 36 (10000)10 36 (10000)10 11 Cadmium7440-43-9nc12092769.1 Carbon Disulfide75-15-0nc500 (1600)10 500 (1100)10 500 (800)10 2.9 Carbon Tetrachloride56-23-5ca139.16.60.021 Chlordane12789-03-6ca2922170.18 Chlordecone (Kepone)143-50-0ca0.950.700.580.0083 Chloroaniline, p-106-47-8ca4735290.015 Chlorobenzene108-90-7nc180 (370)10 180 (250)10 180 (180)10 0.46 Chloroform67-66-3ca5.84.02.90.0071 Chloromethane74-87-3nc2501701200.61 Chloronaphthalene, Beta-91-58-7nc84006200510026 Chlorophenol, 2-95-57-8nc6805104100.71 Chromium(llI), Insoluble Salts1216065-83-1nc1.0 x 105;9 1.0 x 105;9 1.0 x 105;9 1.0 x 105;9 Chromium(Vl)1218540-29-9m4.93.93.20.089 Chrysene7218-01-9m200015001200600 Copper7440-50-8nc550041003300370 Cresol, m-108-39-4nc5500410034006.1 Cresol, o-95-48-7nc5500410034006.2 Cresol, p-106-44-5nc110008200670012 Cumene98-82-8nc54 (2500)10 54 (1700)10 54 (1300)10 5.6 Cyanide (CN-)1357-12-5nc4834260.20 Cyclohexane110-82-7nc77 (14000)10 77 (9400)10 77 (6700)10 150 DDD72-54-8ca3.32.52.00.098 DDE,p,p'-72-55-9ca3425200.72 DDT50-29-3ca3324205.1 Dibenz[a,h]anthracene753-70-3m2.01.51.26.3 Dibenzofuran132-64-9nc13095770.97 Dibromochloromethane124-48-1ca140110880.0027 Dibromoethane, 1,2- (Ethylene Dibromide)106-93-4ca0.620.420.310.00024 Dibromomethane (Methylene Bromide)74-95-3nc4531220.025 Dibutyl Phthalate84-74-2nc110008200670016 Dichlorobenzene, 1,2-95-50-1nc78 (2300)10 78 (1600)10 78 (1200)10 2.4 Dichlorobenzene, 1,3-8541-73-1nc62 (2000)10 62 (1400)10 62 (1000)10 2.3 Dichlorobenzene, 1,4-106-46-7ca3121150.037 Dichlorobenzidine, 3,3'-91-94- 1ca2116130.056 Dichlorodifluoromethane75-71-8nc2201501103.9 Dichloroethane, 1,1-75-34-3ca6746330.092 Dichloroethane, 1,2-107-06-2ca8.05.53.90.0055 Dichloroethylene, 1,1-75-35-4nc4803302401.2 Dichloroethylene, 1,2-cis-156-59-2nc2702001700.12 Dichloroethylene, 1,2-trans-156-60-5nc960 (2700)10 960 (2000)10 960 (1700)10 1.3 Dichlorophenol, 2,4-120-83-2nc3302502000.21 Dichlorophenoxy Acetic Acid, 2,4-94-75-7nc12009107400.53 Dichloropropane, 1,2-78-87-5nc2517120.030 Dichloropropene, 1,3-542-75-6ca3021150.018 Dieldrin60-57-1ca0.590.440.360.0047 Diethyl Phthalate84-66-2nc88000660005400060 Dimethylphenol, 2,4-105-67-9nc2200160013003.2 Dimethylphthalate8131-11-3nc88000660005400048 Dinitrobenzene, 1,2-528-29-0nc118.26.70.014 Dinitrobenzene. 1,3-99-65-0nc118.26.70.014 Dinitrobenzene, 1,4-100-25-4nc118.26.70.014 Dinitrophenol, 2,4-51-28-5nc2201601300.34 Dinitrotoluene, 2,4-121-14-2ca3023180.024 Dinitrotoluene, 2,6-606-20-2ca6.34.73.80.0050 Dinitrotoluene, 2-Amino-4,6-35572-78-2nc2702001600.25 Dinitrotoluene, 4-Amino-2,6-19406-51-0nc2702001600.25 Dioxane, 1,4-123-91-1ca10073580.012 Diphenylamine122-39-4nc110008200670017 Endosulfan (Endosulfan I + Endosulfan II)115-29-7nc8206105009.3 Endrin72-20-8nc3325200.61 Ethyl Chloride75-00-3nc1400 (29000)10 1400 (20000)10 1400 (14000)10 72 Ethylbenzene7100-41-4ca7249350.13 Ethylene Glycol107-21-1nc1.0 x 105;9 1.0 x 105;9 1.0 x 105;9 110 Fluoranthene7206-44-0nc420031002500590 Fluorene786-73-7nc42003100250036 Formaldehyde50-00-0ca4302902100.011 Heptachlor76-44-8ca2.21.61.30.0076 Heptachlor Epoxide1024-57-3ca1.20.860.690.0019 Hexachlorobenzene118-74-1ca2.82.01.50.0082 Hexachlorobutadiene87-68-3nc3.3 (14)10 3.3 (10)10 3.3 (7.2)10 0.020 Hexachlorocyclohexane, Alpha-319-84-6ca1.51.10.910.0029 Hexachlorocyclohexane. Beta-319-85-7ca5.33.93.20.010 Hexachlorocyclohexane, Gamma- (Lindane)58-89-9ca9.97.46.00.016 Hexachlorocyclopentadiene77-47-4nc2.01.41.00.0093 Hexachloroethane67-72-1ca2517120.018 Hcxahydro-1,3,5-trinitro- 1,3,5-triazine (RDX)121-82-4ca11079640.027 Hexane, N-110-54-3nc140 (1600)10 140 (1100)10 140 (750)10 13010 Hexanone, 2-591-78-6nc3802702100.11 Hydrazine302-01-2ca0.760.550.403.1 x 10-5 lndeno[1,2,3-cd]pyrene7193-39-5m20151265 lsophorone78-59-1ca10000740061002.7 lsopropanol67-63-0nc14000950068001.1 Lead and Compounds147439-92-1nc400400400n/a Manganese7439-96-5nc290027002000370 Mercuric Chloride87487-94-7nc4130253.9 Mercury (elemental)7439-97-6nc3.1 (28)10 3.1 (19)10 3.1 (14)10 0.36 Methanol67-56-1nc1.0 x 105;9 1.0 x 105;9 1.0 x 105;9 54 Methoxychlor72-43-5nc55041034013 Methyl Ethyl Ketone (2-Butanone)78-93-3nc23000 (53000)10 23000 (38000)10 23000 (30000)10 15 Methyl lsobutyl Ketone (4-methyl-2-pentanone)108-10-1nc2200 (69000)10 2200 (47000)10 2200 (34000)10 18 Methyl Mercury22967-92-6nc14108.3180 Methyl tert-Butyl Ether (MTBE)1634-04-4ca9706704800.40 Methylene Chloride75-09-2nc6304603600.33 Methylnaphthalene, 1-90-12-0ca68 (310)10 68 (230)10 68 (190)10 0.41 Methylnaphthalene, 2-91-57-6nc4203102501.3 Naphthalene791-20-3ca4229200.038 Nickel Soluble Salts7440-02-0nc260020001700340 Nitrobenzene98-95-3ca6443310.0079 Nitroglycerin55-63-0nc118.26.70.0082 Nitroguanidine556-88-7nc11000820067005.8 Nitrosodimethylamine, N-62-75-9m0.0360.0260.0203.3 x 10-6 Nitroso-di-N-propylamine, N-621-64-7ca1.41.000.820.00068 Nitrosodiphenylamine, N-86-30-6ca1900140012004.6 Nitrotoluene, m-99-08-1nc118.26.70.013 Nitrotoluene, o-88-72-2ca5541340.024 Nitrotoluene, p-99-99-0nc4403302700.32 Octahydro-1,3,5,7- tetranitro-1,3,5,7- tetrazocine (HMX)2691-41-0nc6700500041009.7 Octyl Phthalate, di-N117-84-0nc1100820670370 Pentachlorophenol87-86-5ca1813110.0043 Pentaerythritol tetranitrate (PETN)78-11-5nc2201601300.43 Perchlorate and Perchlorate salts14797-73-0nc9671580.037 Perfluorooctanesulfonic Acid (PFOS)81763-23-1nc2.21.61.30.0030 Perfluorooctanoic Acid (PFOA)8335-67-1nc2.21.61.30.0017 Phenanth- rene7,885-01-8nc31002300190039 Phenol108-95-2nc33000250002000029 Phosphorus, White7723-14-0nc2.72.01.70.020 Polychlorinated Biphenyls (total)151336-36-3ca1.01.01.0n/a Propyl benzene103-65-1nc52 (5200)10 52 (3700)10 52 (2800)10 9.1 Pyrene7129-00-0nc31002300190087 Selenium7782-49-2nc6805104106.9 Silver7440-22-4nc68051041011 Strontium7440-24-6nc8200061000500005600 Styrene100-42-5nc180 (8100)10 180 (5700)10 180 (4200)10 10 TCDD, 2,3,7,8-161746-01-6ca8.2 x 10-5 6.0 x 10-5 4.9 x 10-5 3.9 x 10-6 Tetraehloroethane, 1,1,1,2-630-20-6ca3021150.022 Tetrachloroethane, 1,1,2,2-79-34-5ca8.86.14.40.0030 Tetrachloroethylene127-18-4nc68 (140)10 68 (95)10 68 (69)10 0.19 Tetryl (Trinitrophenylmethylnitramine)479-45-8nc2702001702.5 Thallium (Soluble Salts)7440-28-0nc1.41.000.830.19 Toluene7108-88-3nc200 (8000)10 200 (5800)10 200 (4500)10 6.7 Toxaphene8001-35-2ca8.66.45.20.72 Trichloro-1,2,2- trifluoroethane, 1,1,2-76-13-1nc740 (16000)10 740 (11000)10 740 (7700)10 310 Trichlorobenzene, 1,2,3-87-61-6nc11081660.15 Trichlorobenzene, 1,2,4-120-82-1nc6645320.082 Trichloroethane, 1,1,1-71-55-6nc360 (160000)10 360 (11000)10 360 (7800)10 32 Trichloroethane, 1,1,2-79-00-5nc2.31.61.10.0014 Trichloroethylene79-01-6nc7.14.93.50.011 Trichlorofluoromethane75-69-4nc980 (41000)10 980 (30000)10 980 (25000)10 41 Trichlorophenol, 2,4,5-95-95-4nc110008200670028 Trichlorophenol, 2,4,6-88-06-2nc11082670.092 Trichlorophenoxyacetic Acid, 2,4,5-93-76-5nc11008206700.66 Trichlorophenoxypropionic acid, -2,4,593-72-1nc8806605400.55 Trichloropropane, 1,2,3-96-18-4m0.0890.0660.0543.1 x 10-5 Trimethylbenzene, 1,2,4-95-63-6nc43 (400)10 43 (280)10 43 (210)10 0.61 Trimethylbenzene, 1,3,5-108-67-8nc37 (360)10 37 (250)10 37 (180)10 0.66 Tri-n-butyltin688-73-3nc4130250.68 Trinitrobenzene, 1,3,5-99-35-4nc39002900240015 Trinitrotoluene, 2,4,6-118-96-7nc6447390.39 Vanadium and Compounds7440-62-2nc6805104201100 Vinyl Acetate108-05-4nc2100140010001.1 Vinyl Chloride75-01-4ca0.690.650.610.00080 Xylenes71330-20-7nc57 (710)10 57 (490)10 57 (350)10 1.5 Zinc and Compounds7440-66-6nc4100030000250004900 See notes to table for further requirements "n/a" means not applicable. NOTES TO TABLE B1 FOLLOW TABLE B2 IN (d) OF THIS SECTION
4. (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. TABLE B2. METHOD TWO - PETROLEUM HYDROCARBON SOIL CLEANUP LEVELS Petroleum Hydrocarbon Range Arctic Zone2 mg/kgUnder 40 Inch Zone3Over 40 Inch Zone4Maximum Allowable Concentra- tions17 mg/kgIngestion (mg/kg)18Inhalation (mg/kg)19Migration to Ground- water (mg/kg)6Ingestion (mg/kg)18Inhalation (mg/kg) Migration to Ground- water (mg/kg)6Ingestion (mg/kg)18Inhalation (mg/kg)19Migration to Ground- water (mg/kg)6For Laboratory Analysis using AK Methods 101, 102, and 103 C6-C10 GRO using AK 10114001400n/a14001400300140014002601400C10-C25 DRO using AK 1021250012500n/a102501250025082501250023012500C25-C36 RRO using AK 1031370022000n/a100002200011000830022000970022000For Laboratory Analysis using AK Aliphatic and Aromatic Fraction Methods 101AA, 102AA, and 103AA C6-C10 Aliphatics10001000n/a10001000270100010002401000C6-C10 Aromatics10001000n/a10001000150100010001301000C10-C25 Aliphatics1000010000n/a10000100007200830010000640010000C10-C25 Aromatics50005000n/a4100500010033005000905000C25-C36 Aliphatics2000020000n/a20000200002000020000200002000020000C25-C36 Aromatics410010000n/a300100003300250010000290010000See notes to table for further requirements. ''n/a'' means not applicable. Notes to Tables B1 and B2: If applicable, alternative cleanup 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 are not currently available or calculated levels exceed the calculated saturation concentration, the cleanup level that applies at a site is the calculated saturation concentration determined using the equations set out in the Procedures for Calculating Cleanup Levels, 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 human health, ingestion, inhalation, or migration to groundwater. Where the superscript figure "9" follows the exponent "105", separated by a semicolon, the figure "9" refers to Note 9. 1. "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. 2. "Arctic zone" is defined at 18 AAC 75.990. 3. "Under 40 inch zone" means a site that receives mean annual precipitation of less than 40 inches each year. 4. "Over 40 inch zone" means a site that receives mean annual precipitation of 40 or more inches each year. 5. The "Human Health" exposure pathway is the cumulative exposure pathway through dermal contact, ingestion, and inhalation of volatile and particulate compounds from hazardous substances in the soil but excludes the vapor intrusion pathway of indoor air inhalation. 6. The "Migration to Groundwater" exposure pathway is the potential for hazardous substances to leach to groundwater where they may result in a completed human health exposure pathway through dermal contact, ingestion, or inhalation of contaminants at or above levels listed in Table C at 18 AAC 75.345(b)(1); soil cleanup levels protective of migration to surface water must be determined on a site-specific basis. 7. 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, acenapthylene, anthracene, benz[a]anthracene, benzo[a]pyrene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[g,h,i]pyrene, chrysene, dibenz[a,h]anthracene, fluoranthene, fluorene, indeno[1,2,3-c,d]pyrene, naphthalene, phenanthrene, 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. 8. Where one or more toxicological values were unavailable, toxicity values from surrogate compounds or other sources were used as presented in Table 6 in the Procedures for Calculating Cleanup Levels, adopted by reference in 18 AAC 75.340. 9. The ceiling limit of 100,000 mg/kg is equivalent to a chemical representing 10 percent by weight of the soil sample. At this contaminant concentration and higher, the assumptions for soil contact may be violated (for example, soil adherence and wind-borne dispersion assumptions) due to the presence of the foreign substance itself. 10. This level is based on a soil saturation concentration (Csat) using the equations set out in Procedures for Calculating Cleanup Levels, adopted by reference in 18 AAC 75.340. The Csat value is listed first, followed by the human health risk-based cleanup level in parentheses. The human health risk-based cleanup level assumptions do not take free product into consideration. In accordance with 18 AAC 75.325(f), free product must be recovered to the maximum extent practicable. Contaminant concentrations above the Csat value trigger the need to assess the practicability of product recovery; if the department determines product recovery is impracticable, the risk-based cleanup level may be applied as long as the cumulative risk standards are met. 11. Due to the prevalence of naturally occurring arsenic throughout the state, arsenic at a site will be considered background arsenic unless anthropogenic contribution from a source, activity, or mobilization by means of another introduced contaminant is known or suspected. 12. Due to the prevalence of naturally occurring chromium III throughout the state, sample results reported for total chromium detected at a site will be considered background chromium III unless anthropogenic contribution of chromium III or VI from a source, activity, or mobilization by means of another introduced contaminant is known or suspected. The calculated chromium III migration to groundwater cleanup level exceeds 1,000,000 parts per million. 13. Cyanide expressed as free, or physiologically available cyanide. 14. Lead cleanup levels are 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 800 mg/kg; through an approved site-specific risk assessment, conducted according to the Risk Assessment Procedures Manual, adopted by reference in 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 Risk Assessment Procedures 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. 15. The applicable EPA regulation governing disposal and cleanup of PCB contaminated facilities under 40 C.F.R. 761.61 (PCB remediation waste) may apply to cleanup of polychlorinated biphenyls (PCBs) at a contaminated site. The PCB cleanup levels listed in Table Bl are based on cleanup levels referred to in 40 C.F.R. 761.61 for high occupancy areas with no cap. For unrestricted land use, polychlorinated biphenyls (PCBs) in soil shall be cleaned up to the listed value, unless the department determines that a different cleanup level is necessary as provided in 18 AAC 75.340(i); 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 15, "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. 16. This cleanup level is for 2,3,7,8-Tetrachlorordibenzo-p-Dioxin (TCDD) only; all cleanup levels for polychlorinated dibenzo-p-dioxin (PCDD) and polychlorinated dibenzofuran (PCDF) congeners must be determined on a site-specific basis using he TCDD toxicity equivalent (TEQ) approach described in the Procedures for Calculating Cumulative Risk, adopted by reference in 18 AAC 75.325. 17. This level is the concentration 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). 18. "Ingestion" means a potential pathway or exposure to hazardous substances through direct consumption of the soil. 19. "Inhalation" means a potential pathway to volatile organic hazardous substances in the soil through volatilization, but excludes the vapor intrusion pathway of indoor air inhalation.

(Eff. 1/22/99, Register 149; am 8/27/2000, Register 155; am 1/30/2003, Register 165; am 10/9/2008, Register 188; am 11/6/2016, Register 220; am 9/29/2018, Register 227)

Authority: AS 46.03.020, AS 46.03.740, AS 46.04.070, AS 46.03.050, AS 46.03.745, AS 46.09.020, AS 46.03.710, AS 46.04.020