18 Alaska Admin. Code § 75.341

Current through September 25, 2024

Section 18 AAC 75.341 - Soil cleanup levels; tables

(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

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 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-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 60º Centigrade and 170º 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 170º Centigrade and 400º 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 400º Centigrade and 500º 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.

(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 ARCTIC ZONES 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 chemica ls 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 Substance	CAS Number1	health effect that drives risk: carcinogenic (a); noncarcinogen (nc); mutasren (m)	Arctic Zone2	Under 40 Inch Zone3	Over 40 Inch Zone4	Migration to Groundwater6 (mg/kg)
			Human Health5 (mg/kg)	Human Health5 (mg/kg)	Human Health5 (mg/kg)
Acenaphthene7	83-32-9	nc	6300	4600	3800	37
Acenaphthylene7x	208-96-8	nc	3100	2300	1900	18
Acetone	67-64-1	nc	1.0 x 10 5. 9	81000	65000	38
Aldrin	309-00-2	ca	0.67	0.49	0.40	0.0099
Ammonium Perchlorate	7790-98-9	nc	96	71	58	0.037
Anthracene7	120-12-7	nc	31000	23000	19000	390
Antimony (metallic)	7440-36-0	nc	55	41	33	4.6
Arsenic, Inorganic11	7440-38-2	ca	12	8.8	7.2	0.20
Barium	7440-39-3	nc	25000	20000	17000	2100
Benz[a]anthracene7	56-55-3	m	2.7	2.0	1.7	0.28
Benzaldehyde	100-52-7	nc	77010	77010	77010	0.52
Benzene7	71-43-2	ca	16	11	8.1	0.022
Benzo[a]pyrene7	50-32-8	m	0.28	0.20	0.17	0.27
Benzo[b] fluoranthene7	205-99-2	m	2.8	2.0	1.7	2.7
Benzo[g,h.i]perylene7,8	191-24-2	nc	3100	2300	1900	15000
Benzo[k]fluoranthene7	207-08-9	m	28	20	17	27
Benzoic Acid	55-85-0	nc	1.0 x 10 5. 9	1.0 x 10 5. 9	1.0 x 10 5. 9	200
Benzyl Alcohol	100-51-6	nc	11000	8200	6700	5.7
Beryllium and compounds	7440-41-7	nc	270	200	170	260
Bis(2-chloroethyl)ether	111 -44-4	ca	4.0	2.8	2.1	0.00042
Bis(2-ethyIhexyl)phthalate	117-81-7	ca	680	500	410	88
Bromobenzene	108-86-1	nc	16010	16010	16010	0.36
Bromodichloromethane	75-27-4	ca	5.3	3.6	2.6	0.0043
Bromoform	75-25-2	ca	340	240	170	0.10
Bromomethane	74-83-9	nc	15	10	7.4	0.024
Butadiene, 1,3-	106-99-0	ca	1.2	0.86	0.64	0.0012
Butanol, N-	71-36-3	nc	650010	650010	650010	5.3
Butyl Benzyl Phthalate	85-68-7	ca	5000	3700	3000	16
Butylbenzene, n-	104-51-8	nc	20 10	2010	2010	23
Butylbenzene, sec-	135-98-8	nc	28 10	2810	2810	42
Butylbenzene, tert-	98-06-6	nc	3510	3510	3510	11
Cadmium (Diet)	7440-43-9	nc	120	92	76	9.1
Carbon Disulfide	75-15-0	nc	50010	50010	50010	2.9
Carbon Tetrachloride	56-23-5	ca	13	9.1	6.6	0.021
Chlordane	12789-03-6	ca	29	22	17	0.18
Chlordecone(Kepone)	143-50-0	ca	0.95	0.70	0.58	0.0083
Chloroaniline, p-	106-47-8	ca	47	35	29	0.015
Chlorobenzene	108-90-7	nc	18010	18010	18010	0.46
Chloroform	67-66-3	ca	5.8	4.0	2.9	0.0071
Chloromethane	74-87-3	nc	250	170	120	0.61
Chloronaphtlhalene, Beta-	91-58-7	nc	8400	6200	5100	26
Chlorophenol, 2-	95-57-8	nc	680	510	410	0.71
Chromium(III), Insoluble Salts12	16065-83-1	nc	1.0 x 105, 9	1.0 x 10 5, 9	1.0 x 10 5, 9	1.0 x 10 5, 9
Chromium(VI)12	18540-29-9	m	4.9	3.9	3.2	0.089
Chrysene7	218-01-9	m	280	200	170	82
Copper	7440-50-8	nc	5500	4100	3400	370
Cresol, m-	108-39-4	nc	5500	4100	3400	6.1
Cresol, o-	95-48-7	nc	5500	4100	3400	6.2
Cresol, p-	106-44-5	nc	11000	8200	6700	12
Cumene	98-82-8	nc	54 10	5410	5410	5.6
Cyanide (CN-)13	57-12-5	nc	48	34	26	0.20
Cyclohexane	110-82-7	nc	7710	7710	7710	150
DDD	72-54-8	ca	40	29	24	0.49
DDE. p,p'-	72-55-9	ca	34	25	20	0.72
DDT	50-29-3	ca	33	24	20	5.1
Dibenz[a,h]anthracene7	53-70-3	m	0.28	0.20	0.17	0.87
Dibenzofuran	132-64-9	nc	130	95	77	0.97
Dibromochloromethane	124-48-1	ca	140	110	88	0.0027
Dibromoethane. 1.2- (Ethylene Dibromide)	106-93-4	ca	0.62	0.42	0.31	0.00024
Dibromomethane (Methylene Bromide)	74-95-3	nc	45	31	22	0.025
Dibutyl Phthalate	84-74-2	nc	11000	8200	6700	16
Dichlorobenzene, 1.2-	95-50-1	nc	7810	7810	78 10	2.4
Dichlorobenzene, 1,3-8	541-73-1	nc	6210	6210	6210	2.3
Dichlorobenzene. 1.4-	106-46-7	ca	31	21	15	0.037
Dichlorobenzidine. 3,3'-	91-94-1	ca	21	16	13	0.056
Dichlorodifluoromethane	75-71-8	nc	220	150	110	3.9
Diehloroethane, 1.1-	75-34-3	ca	67	46	33	0.092
Diehloroethane, 1.2-	107-06-2	ca	7.9	5.5	3.9	0.0055
Dichloroeihylene, 1,1-	75-35-4	nc	480	330	240	1.2
Dichloroethylene, 1,2-cis-	156-59-2	nc	270	200	170	0.12
Dichloroethylene, 1,2-trans-	156-60-5	nc	96010	96010	96010	1.3
Dichlorophenol. 2.4-	120-83-2	nc	330	250	200	0.21
Dichlorophenoxy Acetie Acid, 2.4-	94-75-7	nc	1200	910	740	0.53
Dichloropropane, 1,2-	78-87-5	ca	16	11	8.0	0.016
Dichloropropene, 1,3-	542-75-6	ca	29	21	15	0.018
Dieldrin	60-57-1	ca	0.59	0.44	0.36	0.0047
Diethyl Phthalate	84-66-2	nc	88000	66000	54000	60
Dimethylphenol, 2.4-	105-67-9	nc	2200	1600	1300	3.2
Dimethylphthalate8	131-1 1-3	nc	88000	66000	54000	48
Dinitrobenzene, 1,2-	528-29-0	nc	11	8.2	6.7	0.014
Dinitrobenzene, 1.3-	99-65-0	nc	11	8.2	6.7	0.014
Dinitrobenzene, 1.4-	100-25-4	nc	11	8.2	6.7	0.014
Dinitrophenol, 2,4-	51-28-5	nc	220	160	130	0.34
Dinitrotoluene, 2,4-	121-14-2	ca	30	23	18	0.024
Dinitrololuene, 2.6-	606-20-2	ca	6.3	4.7	3.8	0.0050
Dinitrotoluene, 2-A mino-4,6-	35572-78-2	nc	270	200	160	0.25
Dinitrololuene, 4-A mino-2,6-	19406-51-0	nc	270	200	160	0.25
Dioxane, 1,4-	123-91-1	ca	100	73	58	0.012
Diphenylamine	122-39-4	nc	2800	2000	1700	4.3
Endosulfan	1 15-29-7	nc	820	610	500	9.3
Endrin	72-20-8	nc	33	25	20	0.61
Ethyl Chloride	75-00-3	nc	140010	I40010	140010	72
Ethylbenzene7	100-41-4	ca	72	49	35	0.13
Ethylene Glycol	107-21-1	nc	1.0 x 10 5, 9	1.0 x 10 5, 9	1.0 x 10 5, 9	110
Fluoranthene7	206-44-0	nc	4200	3100	2500	590
Fluorene7	86-73-7	nc	4200	3100	2500	36
Formaldehyde	50-00-0	ca	430	290	210	0.011
Heptachlor	76-44-8	ca	2.2	1.6	1.3	0.0076
Heptachlor Epoxide	1024-57-3	ca	1.2	0.86	0.69	0.0019
Hexachlorobenzene	118-74-1	ca	2.8	2.0	1.5	0.0082
Hexachlorobutadiene	87-68-3	nc	3.310	3.310	3.310	0.020
Hexachlorocyclohexane, Alpha-	319-84-6	ca	1.5	1.1	0.91	0.0029
Hexachlorocyclohexane, Bela-	319-85-7	ca	5.3	3.9	3.2	0.010
Hexachlorocyclohexane, Gamma- (Lindane)	58-89-9	ca	9.9	7.4	6.0	0.016
Hexachlorocyclopentadiene	77-47-4	nc	2.0	1.4	1.0	0.0093
Hexachloroethane	67-72-1	ca	24	17	12	0.018
Hexahydro-l,3.5-trinitro-1.3,5-triazine (RDX)	121-82-4	ca	110	79	64	0.027
Hexane, N-	110-54-3	nc	13010	13010	13010	13010
Hexanone, 2-	591-78-6	nc	380	270	210	0.11
Hydrazine	302-01-2	ca	0.79	0.55	0.40	2.9 x 10-5
Indeno[1,2,3-cd]pyrene7	193-39-5	m	2.8	2.0	1.7	8.8
Isophorone	78-59-1	ca	10000	7400	6100	2.7
Isopropanol	67-63-0	nc	14000	9500	6800	1.1
Load and Compounds14	7439-92-1	nc	400	400	400	n/a-6
Mercuric Chloride8	7487-94-7	nc	41	30	25	3.9
Mercury (elemental)	7439-97-6	nc	3.110	3.110	3.110	0.36
Methanol	67-56-1	nc	1.0 x 10 5.9	1.0 x 105.9	1.0 x 10 5.9	54
Methoxychlor	72-43-5	nc	550	410	340	13
Methyl Ethyl Ketone (2-Butanone)	78-93-3	nc	23000 10	2300010	23000 10	15
Methyl Isobulyl Ketone (4-methyl-2-penlanone)	108-10-1	nc	2200 10	220010	2200 10	18
Methyl Mercury	22967-92-6	nc	14	10	8.3	180
Methyl tert-Butyl Ether (MTBE)	1634-04-4	ca	970	670	480	0.40
Methylene Chloride	75-09-2	nc	630	460	360	0.33
Methylnaphthalene, 1 -	90-12-0	ca	6810	6810	6810	0.41
Methylnaphthalene, 2-	91-57-6	nc	420	310	250	1.3
Naphthalene7	91-20-3	ca	42	29	20	0.038
Nickel Soluble Salts	7440-02-0	nc	2600	2000	1700	340
Nitrobenzene	98-95-3	ca	63	43	31	0.0079
Nitroglycerin	55-63-0	nc	11	8.2	6.7	0.0082
Nitroguanidine	556-88-7	nc	11000	8200	6700	5.8
Nitrosodimethylamine, N-	62-75-9	m	0.036	0.026	0.020	3.3 x 10-6
Nitroso-di-N-propylamine, N-	621 -64-7	ca	1.4	1.00	0.82	0.00068
Nitrosodiphenylamine, N-	86-30-6	ca	1900	1400	1200	4.6
Nitrotoluene, m-	99-08-1	nc	11	8.2	6.7	0.013
Nitrotoluene, o-	88-72-2	ca	55	41	34	0.024
Nitrotoluene, p-	99-99-0	nc	440	330	270	0.32
Octahydro-1.3, 5.7-tetranitro-1.3, 5.7-tctrazocine (HMX)	2691-41-0	nc	6700	5000	4100	9.7
Octyl Phthalate, di-N-	117-84-0	nc	1100	820	670	370
Pentachlorophenol	87-86-5	ca	18	13	11	0.0043
Pentaerythritol tetranitrate (PETN)	78-11-5	nc	220	160	130	0.43
Perfluorooctane, Sulfonate-(PFOS)-20	1763-23-1	nc	2.2	1.6	1.3	0.0030
Perfluorooctanoic Acid (PFOA)-20	335-67-1	nc	2.2	1.6	1.3	0.0017
Phenanthrene7, 8	85-01-8	nc	3100	2300	1900	39
Phenol	108-95-2	nc	33000	25000	20000	29
Phosphorus, White	7723-14-0	nc	2.7	2.0	1.7	0.020
Polychlorinaled Biphenyls (total)15	1336-36-3	ca	1.0	1.0	1.0	n/a-6
Propyl benzene	103-65-1	nc	5210	5210	52 10	9.1
Pyrene7	129-00-0	nc	3100	2300	1900	87
Selenium	7782-49-2	nc	680	510	410	6.9
Silver	7440-22-4	nc	680	510	410	11
Styrene	100-42-5	nc	180 10	18010	18010	10
TCDD, 2,3,7,8-16	1746-01-6	ca	8.2 x 10-5	6.0 x 10-5	4.9 x 10-5	3.9 x 10-6
Tetraehlorocthane,1.1.1.2-	630-20-6	ca	30	21	15	0.022
Tetrachlorocthane.1.1.2.2-	79-34-5	ca	8.8	6.1	4.4	0.0030
Tetrachloroethylene	127-18-4	nc	68 10	6810	6810	0.19
Tetryl (Trinitrophenylmethy lnitramine)	479-45-8	nc	270	200	170	2.5
Thallium (Soluble Salts)	7440-28-0	nc	1.4	1.00	0.83	0.19
Toluene7	108-88-3	nc	20010	20010	20010	6.7
Toxaphene	8001-35-2	ca	8.6	6.4	5.2	0.72
Trichloro-1 ,2,2-trifluoroethane, 1,1,2-	76-13-1	nc	74010	74010	74010	1700
Trichlorobenzene, 1,2,3-	87-61-6	nc	110	81	66	0.15
Trichlorobenzene, 1.2,4-	120-82-1	nc	65	45	32	0.082
Trichloroethane, 1,1,1-	71-55-6	nc	36010	36010	36010	32
Trichloroethane, 1.1,2-	79-00-5	nc	2.3	1.6	1.1	0.0014
Trichloroethylene	79-01-6	nc	7.1	4.9	3.5	0.011
Trichlorofluoromethane	75-69-4	nc	980 10	98010	980 10	41
Trichlorophenol, 2,4,5-	95-95-4	nc	11000	8200	6700	28
Trichlorophenol, 2,4,6-	88-06-2	nc	110	82	67	0.092
Trichlorophenoxyacetic Acid. 2,4.5-	93-76-5	nc	1100	820	670	0.66
Trichlorophenoxypropionic acid. -2,4.5	93-72-1	nc	880	660	540	0.55
Trichloropropane, 1,2,3-	96-18-4	m	0.089	0.066	0.054	3.1 x 10 -5
Trimethylbenzene, 1.2,4-	95-63-6	nc	4310	4310	33	0.16
Trimethylbenzene, 1,3,5-	108-67-8	nc	37 10	3710	3710	1.3
Tri-n-butyltin	688-73-3	nc	41	30	25	0.68
Trinitrobenzene, 1,3,5-	99-35-4	nc	3900	2900	2400	15
Trinitrotoluene, 2,4,6-	118-96-7	nc	64	47	39	0.39
Vanadium and Compounds	7440-62-2	nc	680	510	420	1100
Vinyl Acetate	108-05-4	nc	2100	1400	1000	1.1
Vinyl Chloride	75-01-4	ca	0.69	0.65	0.61	0.00080
Xylenes7	1330-20-7	nc	5710	5710	5710	1.5
Zinc and Compounds	7440-66-6	nc	41000	30000	25000	4900
See notes to table for further requirements "n/a" means not applicable.

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.

TABLE B2. METHOD TWO - PETROLEUM HYDROCARBON SOIL CLEANUP LEVELS
Petroleum Hydrocarbon Range	Arctic Zone2 mg/kg			Under 40 Inch Zone3			Over 40 Inch Zone4			Maximum Allowable Concentrations17mg/kg
	Ingestion (mg/kg)18	Inhalation (mg/kg)19	Migration to Groundwater (mg/kg)6	Ingestion (mg/kg)18	Inhalation (mg/kg)19	Migration to groundwater (mg/kg)6	Ingestion (mg/kg)18	Inhalation (mg/kg)19	Migration to Groundwater (mg/kg)6
For Laboratory Analysis using AK Methods 101, 102, and 103
C6-C10GRO using AK 101	1400	1400	n/a	1400	1400	300	1400	1400	260	1400
C10-C25DRO using AK 102	12500	12500	n/a	10250	12500	250	8250	12500	230	12500
C25-C36 RRO using AK 103	13700	22000	n/a	10000	22000	11000	8300	22000	9700	22000
For Laboratory Analysis using AK Aliphatic and Aromatic Fraction Methods 101AA, 102AA, and 103AA
C6-C10Aliphatics	1000	1000	n/a	1000	1000	270	1000	1000	240	1000
C6-C10Aromatics	1000	1000	n/a	1000	1000	150	1000	1000	130	1000
C10-C25Aliphatics	10000	10000	n/a	10000	10000	7200	8300	10000	6400	10000
C10-C25Aromatics	5000	5000	n/a	4100	5000	100	3300	5000	90	5000
C25-C36Aliphatics	20000	20000	n/a	20000	20000	20000	20000	20000	20000	20000
C25-C36Aromatics	4100	10000	n/a	3000	10000	3300	2500	10000	2900	10000
See 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. Concenlrations of hazardous substances in soil musl be calculaled and presenled on a per dry weight basis. For volatile organic hazardous subslances for which toxicity data are not currently available or calculated levels exceed the calculaled saturalion concentration, the cleanup level lhat applies at a site is the calculated saturation concentration determined using lhe equalions sel out in the Procedures for Calculating Cleanup Levels, adopted by reference in 18 AAC 75.340. The cleanup level from Table B1 or B2 thal applies at a site is the most stringenl of lhe 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.

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1. "CAS Number" means the Chemical Abstracl 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 sile lhat receives mean annual precipitation of less lhan 40 inches each year.

4. "Over 40 inch zone" means a site thal receives mean annual precipitation of 40 or more inches each year.

5. The "Human Health" exposure pathway is the cumulalive 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 compleled 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 chemica l-specific cleanup levels for the polynuclear aromatic hydrocarbons acenaphthene, acenapthylene, anthraccne, benz[a]anthracene, benzo[ a] pyrene, benzo[b] fluoran thene, benzo[ k] fluoran thene, 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 environmenl.

8. Where one or more toxicological values were unavail able, toxicity values from surrogate compounds or other sources were used as foliows:

(A) pyrene is a toxicity surrogate for acenaphthylene, benzo(g,h,i) perylene, and phenanthrene;

(B) 1,2-dichlorobenzene is a toxicity surrogate for 1,3 -dichlorobenzene;

(C) diethylphthalate is a toxicity surrogate for dimethylphthalate;

(D) elemental mercury is a toxicity surrogate for mercuric chloride.

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. These levels are based on soil saturation level (Csat) using the equations set out in Procedures for Calculating Cleanup Levels, adopted by reference in 18 AAC 75 .340. Refer to the Procedures for Calculating Cumulative Risk, adopted by reference in 18 AAC 75.325, for inhalation risk screening levels.

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 occuring 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 wi th l ead more than 15 feet below ground surface, lead cleanup levels will be determined on a site-specific basis.

15. 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 materi al 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 clays 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.

17. This level is the concentration or 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 th rough direct consumption of the soil.

19 "Inhalation" means a potential pathway to volatile organic hazardous substances in the soil through volatilization.

20. Toxicity values for PFOS and PFOA were sourced from EPA's Health Effects Support Document for Perfluorooctane Sulfanate (PFOS) (EPA 822-R-16-002), dated May 2016, and Health Effects Supports Document for Perfluorooctanatic Acid (PFOA) (EPA 822-R-16-003), dated May 2016.

18 AAC 75.341

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, January 2017

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.

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