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(continued)
(B) Whether changes to the ground water chemistry due to natural attenuation processes would cause an exceedance of surface water or sediment quality standards.
(9) Compliance monitoring.
(a) When ground water cleanup levels have been established at a site, sampling of the ground water shall be conducted to determine if compliance with the ground water cleanup levels has been achieved. Compliance with ground water cleanup levels shall be determined by analysis of ground water samples representative of the ground water. Surface water analysis, bioassays or other biomonitoring methods may also be required where the ground water cleanup level is based on protection of surface water. Sampling and analytical procedures shall be defined in a compliance monitoring plan prepared under WAC 173-340-410. The sample design shall provide data that are representative of the site.
(b) Analyses shall be conducted on unfiltered ground water samples, unless it can be demonstrated that a filtered sample provides a more representative measure of ground water quality. The department expects that filtering will generally be acceptable for iron and manganese and other naturally occurring inorganic substances where:
(i) A properly constructed monitoring well cannot be sufficiently developed to provide low turbidity water samples;
(ii) Due to the natural background concentration of hazardous substances in the aquifer material, unfiltered samples would not provide a representative measure of ground water quality; and
(iii) Filtering is performed in the field with all practicable measures taken to avoid exposing the ground water sample to the ambient air before filtering.
(c) The data analysis and evaluation procedures used to evaluate compliance with ground water cleanup levels shall be defined in a compliance monitoring plan prepared under WAC 173-340-410. These procedures shall meet the following general requirements:
(i) Methods of data analysis shall be consistent with the sampling design;
(ii) When cleanup levels are based on requirements specified in applicable state and federal laws, the procedures for evaluating compliance that are specified in those requirements shall be used to evaluate compliance with cleanup levels unless those procedures conflict with the intent of this section;
(iii) Where procedures for evaluating compliance are not specified in an applicable state and federal law, statistical methods used shall be appropriate for the distribution of sampling data for each hazardous substance. If the distributions for hazardous substances differ, more than one statistical method may be required;
(iv) Compliance with ground water cleanup levels shall be determined for each ground water monitoring well or other monitoring points such as a spring;
(v) The data analysis procedures identified in the compliance monitoring plan shall specify the statistical parameters to be used to determine compliance with ground water cleanup levels.
(A) For cleanup levels based on short-term or acute toxic effects on human health or the environment, an upper percentile concentration shall be used to evaluate compliance with ground water cleanup levels.
(B) For cleanup levels based on chronic or carcinogenic threats, the true mean concentration shall be used to evaluate compliance with ground water cleanup levels.
(vi) When active ground water restoration is performed, or containment technologies are used that incorporate active pumping of ground water, compliance with ground water cleanup levels shall be determined when the ground water characteristics at the site are no longer influenced by the cleanup action.
(d) When data analysis procedures for evaluating compliance are not specified in an applicable state or federal law, the following procedures shall be used:
(i) A confidence interval approach that meets the following requirements:
(A) The upper one-sided ninety-five percent confidence limit on the true mean ground water concentration shall be less than the ground water cleanup level. For lognormally distributed data, the upper one-sided ninety-five percent confidence limit shall be calculated using Land's method; and
(B) Data shall be assumed to be lognormally distributed unless this assumption is rejected by a statistical test. If a lognormal distribution is inappropriate, data shall be assumed to be normally distributed unless this assumption is rejected by a statistical test. The W test, D'Agostino's test, or, censored probability plots, as appropriate for the data, shall be the statistical methods used to determine whether the data is lognormally or normally distributed.
(ii) Evaluations conducted under subsection (9)(c)(v)(A) of this subsection may use a parametric test for percentiles based on tolerance intervals to test the proportion of ground water samples having concentrations less than the ground water cleanup level. When using this method, the true proportion of samples that do not exceed the ground water cleanup level shall not be less than ninety percent. Statistical tests shall be performed with a Type I error level of 0.05; or
(iii) Other statistical methods approved by the department.
(e) All data analysis methods used, including those specified in state or federal law, must meet the following requirements:
(i) No single sample concentration shall be greater than two times the ground water cleanup level. Higher exceedances to control false positive error rates at five percent may be approved by the department when the cleanup level is based on background concentrations; and
(ii) Less than ten percent of the sample concentrations shall exceed the ground water cleanup level during a representative sampling period. Higher exceedances to control false positive error rates at five percent may be approved by the department when the cleanup level is based on background concentrations; and
(f) When using statistical methods to demonstrate compliance with ground water cleanup levels, the following procedures shall be used for measurements below the practical quantitation limit:
(i) Measurements below the method detection limit shall be assigned a value equal to one-half the method detection limit when not more than fifteen percent of the measurements are below the practical quantitation limit.
(ii) Measurements above the method detection limit but below the practical quantitation limit shall be assigned a value equal to the method detection limit when not more than fifteen percent of the measurements are below the practical quantitation limit.
(iii) When between fifteen and fifty percent of the measurements are below the practical quantitation limit and the data are assumed to be lognormally or normally distributed, Cohen's method shall be used to calculate a corrected mean and standard deviation for use in calculating an upper confidence limit on the true mean ground water concentration.
(iv) If more than fifty percent of the measurements are below the practical quantitation limit, the largest value in the data set shall be used in place of an upper confidence limit on the true mean ground water calculation.
(v) If a hazardous substance or petroleum fraction has never been detected in any sample at a site and these substances are not suspected of being present at the site based on site history and other knowledge, that hazardous substance or petroleum fraction may be excluded from the statistical analysis.
(vi) The department may approve alternate statistical procedures for handling nondetected values or values below the practical quantitation limit.
[Statutory Authority: Chapter 70.105D RCW. 01-05-024 (Order 97-09A), § 173-340-720, filed 2/12/01, effective 8/15/01; 91-04-019, § 173-340-720, filed 1/28/91, effective 2/28/91.]
Notes:
Reviser's note: The brackets and enclosed material in the text of the above section occurred in the copy filed by the agency.
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173-340-730
Surface water cleanup standards.
(1) General considerations.
(a) Surface water cleanup levels shall be based on estimates of the highest beneficial use and the reasonable maximum exposure expected to occur under both current and potential future site use conditions. The classification and the highest beneficial use of a surface water body, determined in accordance with chapter 173-201A WAC, shall be used to establish the reasonable maximum exposure for that water body. Surface water cleanup levels shall use this presumed exposure scenario and shall be established in accordance with this section.
(b) In the event of a release of a hazardous substance to surface water from a site, a cleanup action that complies with this chapter shall be conducted to address all areas of the site where the concentration of the hazardous substances in the surface water exceeds cleanup levels.
(c) Surface water cleanup levels established under this section apply to those surface waters of the state affected or potentially affected by releases of hazardous substances from sites addressed under this chapter. The department does not expect that cleanup standards will be applied to storm water runoff that is in the process of being conveyed to a treatment system.
(d) Surface water cleanup levels shall be established at concentrations that do not directly or indirectly cause violations of ground water, soil, sediment, or air cleanup standards established under this chapter or other applicable state and federal laws. A site that qualifies for a Method C surface water cleanup level under this section does not necessarily qualify for a Method C cleanup level in other media. Each medium must be evaluated separately using the criteria applicable to that medium.
(e) The department may require more stringent cleanup levels than specified in this section where necessary to protect other beneficial uses or otherwise protect human health and the environment. Any imposition of more stringent requirements under this provision shall comply with WAC 173-340-702 and 173-340-708.
(2) Method A surface water cleanup levels.
(a) Applicability. Method A surface water cleanup levels may only be used at sites that qualify under WAC 173-340-704(1).
(b) General requirements. Method A surface water cleanup levels shall be at least as stringent as all of the following:
(i) Concentrations established under applicable state and federal laws, including the following requirements:
(A) All water quality criteria published in the water quality standards for surface waters of the state of Washington, chapter 173-201A WAC, as amended;
(B) Water quality criteria based on the protection of aquatic organisms (acute and chronic criteria) and human health published under section 304 of the Clean Water Act.
(C) National toxics rule (40 C.F.R. Part 131);
(ii) For surface waters that are classified as suitable for use as a domestic water supply under chapter 173-201A (excluding marine waters), concentrations derived using the methods specified in WAC 173-340-720 for drinking water beneficial uses; and
(iii) For a hazardous substance deemed an indicator hazardous substance for surface water under WAC 173-340-708(2) and for which there is no value in applicable state and federal laws, a concentration that does not exceed the natural background concentration or the practical quantitation limit, subject to the limitations in this chapter.
(3) Method B surface water cleanup levels.
(a) Applicability. Method B surface water cleanup levels consist of standard and modified cleanup levels as described in this subsection. Either standard or modified Method B surface water cleanup levels may be used at any site.
(b) Standard Method B surface water cleanup levels. Standard Method B cleanup levels for surface waters shall be at least as stringent as all of the following:
(i) Applicable state and federal laws. Concentrations established under applicable state and federal laws, including the following requirements:
(A) All water quality criteria published in the water quality standards for surface waters of the state of Washington, chapter 173-201A WAC;
(B) Water quality criteria based on the protection of aquatic organisms (acute and chronic criteria) and human health published under section 304 of the Clean Water Act unless it can be demonstrated that such criteria are not relevant and appropriate for a specific surface water body or hazardous substance; and
(C) National toxics rule (40 C.F.R. Part 131);
(ii) Environmental effects. For hazardous substances for which environmental effects-based concentrations have not been established under applicable state or federal laws, concentrations that are estimated to result in no adverse effects on the protection and propagation of wildlife, fish, and other aquatic life. Whole effluent toxicity testing using the protocols described in chapter 173-205 WAC may be used to make this demonstration for fish and aquatic life;
(iii) Human health protection. For hazardous substances for which sufficiently protective, health-based criteria or standards have not been established under applicable state and federal laws, those concentrations that protect human health as determined by the following methods:
(A) Noncarcinogens. For surface waters that support or have the potential to support fish or shellfish populations, concentrations which are estimated to result in no acute or chronic toxic effects on human health as determined using Equation 730-1.
[Equation 730-1]
Surface water cleanup level =
(ug/l) RfD x ABW x UCF1 x UCF2 x HQ x AT
--------------------------------------------------------------------------------
BCF x FCR x FDF x ED
Where:
RfD = Reference dose as specified in WAC 173-340-708(7) (mg/kg-day)
ABW = Average body weight during the exposure duration (70 kg)
UCF1 = Unit conversion factor (1,000 ug/mg)
UCF2 = Unit conversion factor (1,000 grams/liter)
BCF = Bioconcentration factor as defined in WAC 173-340-708(9) (liters/kilogram)
FCR = Fish consumption rate (54 grams/day)
FDF = Fish diet fraction (0.5) (unitless)
HQ = Hazard quotient (1) (unitless)
AT = Averaging time (30 years)
ED = Exposure duration (30 years)
(B) Carcinogens. For surface waters which support or have the potential to support fish or shellfish populations, concentrations that are estimated to result in an excess cancer risk less than or equal to one in one million (1 x 10-6) as determined using Equation 730-2.
[Equation 730-2]
Surface water cleanup level =
(ug/l) RISK x ABW x AT x UCF1 x UCF2
--------------------------------------------------------------------------------
CPF x BCF x FCR x FDF x ED
Where:
CPF = Carcinogenic potency factor as specified in WAC 173-340-708(8) (kg-day/mg)
RISK = Acceptable cancer risk level (1 in 1,000,000) (unitless)
ABW = Average body weight during the exposure duration (70 kg)
AT = Averaging time (75 years)
UCF1 = Unit conversion factor (1,000 ug/mg)
UCF2 = Unit conversion factor (1,000 grams/liter)
BCF = Bioconcentration factor as defined in WAC 173-340-708(9) (liters/kilogram)
FCR = Fish consumption rate (54 grams/day)
FDF = Fish diet fraction (0.5) (unitless)
ED = Exposure duration (30 years)
(C) Petroleum mixtures. For noncarcinogenic effects of petroleum mixtures, a total petroleum hydrocarbon cleanup level shall be calculated using Equation 730-1 and by taking into account the additive effects of the petroleum fractions and volatile hazardous substances present in the petroleum mixture. As an alternative to this calculation, the total petroleum hydrocarbon cleanup levels in Table 720-1 may be used. Cleanup levels for other noncarcinogens and known or suspected carcinogens within the petroleum mixture shall be calculated using Equations 730-1 and 730-2. See Table 830-1 for the analyses required for various petroleum products to use this method; and
(iv) Drinking water considerations. For surface waters that are classified as suitable for use as a domestic water supply under chapter 173-201A WAC, concentrations derived using the methods specified in WAC 173-340-720 for drinking water beneficial uses.
(c) Modified Method B surface water cleanup levels. Modified Method B surface water cleanup levels are standard Method B surface water cleanup levels modified with chemical-specific or site-specific data. When making these adjustments, the resultant cleanup levels shall meet applicable state and federal laws and health risk levels required for standard Method B surface water cleanup levels. Changes to exposure assumptions must comply with WAC 173-340-708(10). The following adjustments may be made to the default assumptions in the standard Method B equations to derive modified Method B surface water cleanup levels:
(i) Adjustments to the reference dose and cancer potency factor may be made if the requirements in WAC 173-340-708 (7) and (8) are met;
(ii) Adjustments to the bioconcentration factor may be made if the requirements in WAC 173-340-708(9) are met;
(iii) Where a numeric environmental effects-based water quality standard does not exist, bioassays that use methods other than those specified in chapter 173-205 WAC may be approved by the department to establish concentrations for the protection of fish and other aquatic life;
(iv) The toxicity equivalency factor procedures described in WAC 173-340-708(8) may be used for assessing the potential carcinogenic risk of mixtures of chlorinated dibenzo-p-dioxins, chlorinated dibenzofurans and polycyclic aromatic hydrocarbons; and
(v) Modifications incorporating new science as provided for in WAC 173-340-702 (14), (15) and (16).
(d) Using modified Method B to evaluate surface water remediation levels. In addition to the adjustments allowed under subsection (3)(c) of this section, adjustments to the reasonable maximum exposure scenario or default exposure assumptions are allowed when using a quantitative site-specific risk assessment to evaluate the protectiveness of a remedy. See WAC 173-340-355, 173-340-357, and 173-340-708 (3)(d) and (10)(b).
(4) Method C surface water cleanup levels.
(a) Applicability. Method C surface water cleanup levels consist of standard and modified cleanup levels as described in this subsection. Either standard or modified Method C cleanup levels may be approved by the department if the person undertaking the cleanup action can demonstrate that such levels are consistent with applicable state and federal laws, that all practicable methods of treatment have been used, that institutional controls are implemented in accordance with WAC 173-340-440, and that one or more of the conditions in WAC 173-340-706(1) exist.
(b) Standard Method C surface water cleanup levels. Method C cleanup levels for surface waters shall be at least as stringent as all of the following:
(i) Applicable state and federal laws. Concentrations established under applicable state and federal laws, including the requirements identified in subsection (3)(b)(i) of this section;
(ii) Environmental effects. For hazardous substances for which an environmental effects based concentration has not been established under applicable state or federal laws, those concentrations which are estimated to result in no significant adverse effects on the protection and propagation of wildlife, fish and other aquatic life. Whole effluent toxicity testing using the protocols described in chapter 173-205 WAC may be used to make this demonstration for fish and aquatic life;
(iii) Human health protection. For hazardous substances for which sufficiently protective, health-based criteria or standards have not been established under applicable state and federal laws, those concentrations which protect human health as determined by the following methods:
(A) Noncarcinogens. For surface waters that support or have the potential to support fish or shellfish populations, concentrations that are estimated to result in no significant acute or chronic toxic effects on human health and are estimated in accordance with Equation 730-1 except that the fish diet fraction shall be twenty percent (0.2);
(B) Carcinogens. For surface waters that support or have the potential to support fish or shellfish populations, concentrations for which the upper bound on the estimated excess cancer risk is less than or equal to one in one hundred thousand (1 x 10-5) and are estimated in accordance with Equation 730-2 except that the fish diet fraction shall be twenty percent (0.2);
(C) Petroleum mixtures. Cleanup levels for petroleum mixtures shall be calculated as specified in subsection (3)(b)(iii)(C) of this section, except that the fish diet fraction shall be twenty percent (0.2); and
(iv) Drinking water considerations. For surface waters that are classified as suitable for use as a domestic water supply under chapter 173-201A WAC, concentrations derived using the methods specified for drinking water beneficial uses in WAC 173-340-720.
(c) Modified Method C surface water cleanup levels. Modified Method C surface water cleanup levels are standard Method C surface water cleanup levels modified with chemical-specific or site-specific data. The same limitations and adjustments specified for modified Method B in subsection (3)(c) of this section apply to modified Method C surface water cleanup levels.
(d) Using modified Method C to evaluate surface water remediation levels. In addition to the adjustments allowed under subsection (4)(c) of this section, adjustments to the reasonable maximum exposure scenario or default exposure assumptions are allowed when using a quantitative site-specific risk assessment to evaluate the protectiveness of a remedy. See WAC 173-340-355, 173-340-357, and 173-340-708 (3)(d) and (10)(b).
(5) Adjustments to cleanup levels.
(a) Total site risk adjustments. Surface water cleanup levels for individual hazardous substances developed in accordance with subsections (3) and (4) of this section, including those based on applicable state and federal laws, shall be adjusted downward to take into account exposure to multiple hazardous substances and/or exposure resulting from more than one pathway of exposure. These adjustments need to be made only if, without these adjustments, the hazard index would exceed one (1) and the total excess cancer risk would exceed one in one hundred thousand (1 x 10-5). These adjustments shall be made in accordance with the procedures specified in WAC 173-340-708 (5) and (6). In making these adjustments, the hazard index shall not exceed one (1) and the total excess cancer risk shall not exceed one in one hundred thousand (1 x 10-5).
(b) Adjustments to applicable state and federal laws. Where a cleanup level developed under subsection (2), (3) or (4) of this section is based on an applicable state or federal law and the level of risk upon which the standard is based exceeds an excess cancer risk of one in one hundred thousand (1 x 10-5) or a hazard index of one (1), the cleanup level shall be adjusted downward so that the total excess cancer risk does not exceed one in one hundred thousand (1 x 10-5) and the hazard index does not exceed one (1) at the site.
(c) Natural background and PQL considerations. Cleanup levels determined under subsections (2), (3) and (4) of this section, including cleanup levels adjusted under subsection (5)(a) and (b) of this subsection, shall not be set at levels below the practical quantitation limit or natural background concentration, whichever is higher. See WAC 173-340-707 and 173-340-709 for additional requirements pertaining to practical quantitation limits and natural background concentrations.
(d) Nonaqueous phase liquid limitation. For organic hazardous substances and petroleum hydrocarbons, the cleanup level shall not exceed a concentration that would result in nonaqueous phase liquid being present in or on the surface water. Physical observations of surface water at or above the cleanup level, such as the lack of a film, sheen, discoloration, sludge or emulsion in the surface water or adjoining shoreline, may be used to determine compliance with this requirement.
(6) Point of compliance.
(a) The point of compliance for the surface water cleanup levels shall be the point or points at which hazardous substances are released to surface waters of the state unless the department has authorized a mixing zone in accordance with chapter 173-201A WAC.
(b) Where hazardous substances are released to the surface water as a result of ground water flows, no mixing zone shall be allowed to demonstrate compliance with surface water cleanup levels. See WAC 173-340-720 (8)(d) for additional requirements for sites where contaminated ground water is flowing into surface water.
(c) As used in this subsection, "mixing zone" means that portion of a surface water body adjacent to an effluent outfall where mixing results in dilution of the effluent with the receiving water. See chapter 173-201A WAC for additional information on mixing zones.
(7) Compliance monitoring.
(a) When surface water cleanup levels have been established at a site, sampling of the surface water shall be conducted to determine if compliance with the surface water cleanup levels has been achieved. Sampling and analytical procedures shall be defined in a compliance monitoring plan prepared under WAC 173-340-410. The sample design shall provide data that are representative of the site.
(b) The data analysis and evaluation procedures used to evaluate compliance with surface water cleanup levels shall be defined in a compliance monitoring plan prepared under WAC 173-340-410.
(c) Compliance with surface water cleanup standards shall be determined by analyses of unfiltered surface water samples, unless it can be demonstrated that a filtered sample provides a more representative measure of surface water quality.
(d) When surface water cleanup levels are based on requirements specified in applicable state and federal laws, the procedures for evaluating compliance that are specified in those requirements shall be used to evaluate compliance with surface water cleanup levels unless those procedures conflict with the intent of this section.
(e) Where procedures for evaluating compliance are not specified in an applicable state and federal law, compliance with surface water cleanup levels shall be evaluated using procedures approved by the department. Where statistical methods are used to evaluate compliance, the statistical methods shall be appropriate for the distribution of the hazardous substance sampling data. If the distribution of the hazardous substance sampling data is inappropriate for statistical methods based on a normal distribution, then the data may be transformed. If the distributions of individual hazardous substances differ, more than one statistical method may be required.
(f) Sampling and analysis of fish tissue, shellfish, or other aquatic organisms and sediments may be required to supplement water column sampling during compliance monitoring.
[Statutory Authority: Chapter 70.105D RCW. 01-05-024 (Order 97-09A), § 173-340-730, filed 2/12/01, effective 8/15/01; 91-04-019, § 173-340-730, filed 1/28/91, effective 2/28/91.]
Notes:
Reviser's note: The brackets and enclosed material in the text of the above section occurred in the copy filed by the agency.
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173-340-740
Unrestricted land use soil cleanup standards.
(1) General considerations.
(a) Presumed exposure scenario soil cleanup levels shall be based on estimates of the reasonable maximum exposure expected to occur under both current and future site use conditions. The department has determined that residential land use is generally the site use requiring the most protective cleanup levels and that exposure to hazardous substances under residential land use conditions represents the reasonable maximum exposure scenario. Unless a site qualifies for use of an industrial soil cleanup level under WAC 173-340-745, soil cleanup levels shall use this presumed exposure scenario and be established in accordance with this section.
(b) In the event of a release of a hazardous substance to the soil at a site, a cleanup action complying with this chapter shall be conducted to address all areas where the concentration of hazardous substances in the soil exceeds cleanup levels at the relevant point of compliance.
(c) The department may require more stringent soil cleanup standards than required by this section where, based on a site-specific evaluation, the department determines that this is necessary to protect human health and the environment. Any imposition of more stringent requirements under this provision shall comply with WAC 173-340-702 and 173-340-708. The following are examples of situations that may require more stringent cleanup levels.
(i) Concentrations that eliminate or substantially reduce the potential for food chain contamination;
(ii) Concentrations that eliminate or substantially reduce the potential for damage to soils or biota in the soils which could impair the use of soils for agricultural or silvicultural purposes;
(iii) Concentrations necessary to address the potential health risk posed by dust at a site;
(iv) Concentrations necessary to protect the ground water at a particular site;
(v) Concentrations necessary to protect nearby surface waters from hazardous substances in runoff from the site; and
(vi) Concentrations that eliminate or minimize the potential for the accumulation of vapors in buildings or other structures.
(d) Relationship between soil cleanup levels and other cleanup standards. Soil cleanup levels shall be established at concentrations that do not directly or indirectly cause violations of ground water, surface water, sediment, or air cleanup standards established under this chapter or applicable state and federal laws. A property that qualifies for a Method C soil cleanup level under WAC 173-340-745 does not necessarily qualify for a Method C cleanup level in other media. Each medium must be evaluated separately using the criteria applicable to that medium.
(2) Method A soil cleanup levels for unrestricted land use.
(a) Applicability. Method A soil cleanup levels may only be used at sites qualifying under WAC 173-340-704(1).
(b) General requirements. Method A soil cleanup levels shall be at least as stringent as all of the following:
(i) Concentrations in Table 740-1 and compliance with the corresponding footnotes;
(ii) Concentrations established under applicable state and federal laws;
(iii) Concentrations that result in no significant adverse effects on the protection and propagation of terrestrial ecological receptors using the procedures specified in WAC 173-340-7490 through 173-340-7493, unless it is demonstrated under those sections that establishing a soil concentration is unnecessary; and
(iv) For a hazardous substance that is deemed an indicator hazardous substance under WAC 173-340-708(2) and for which there is no value in Table 740-1 or applicable state and federal laws, a concentration that does not exceed the natural background concentration or the practical quantification limit, subject to the limitations in this chapter.
(3) Method B soil cleanup levels for unrestricted land use.
(a) Applicability. Method B soil cleanup levels consist of standard and modified cleanup levels determined using the procedures in this subsection. Either standard or modified Method B soil cleanup levels may be used at any site.
(b) Standard Method B soil cleanup levels. Standard Method B cleanup levels for soils shall be at least as stringent as all of the following:
(i) Applicable state and federal laws. Concentrations established under applicable state and federal laws;
(ii) Environmental protection. Concentrations that result in no significant adverse effects on the protection and propagation of terrestrial ecological receptors established using the procedures specified in WAC 173-340-7490 through173-340-7494 unless it is demonstrated under those sections that establishing a soil concentration is unnecessary.
(iii) Human health protection. For hazardous substances for which sufficiently protective, health-based criteria or standards have not been established under applicable state and federal laws, those concentrations that protect human health as determined by evaluating the following exposure pathways:
(A) Ground water protection. Concentrations that will not cause contamination of ground water at levels which exceed ground water cleanup levels established under WAC 173-340-720 as determined using the methods described in WAC 173-340-747.
(B) Soil direct contact. Concentrations that, due to direct contact with contaminated soil, are estimated to result in no acute or chronic noncarcinogenic toxic effects on human health using a hazard quotient of one (1) and concentrations for which the upper bound on the estimated excess cancer risk is less than or equal to one in one million (1 x 10-6). Equations 740-1 and 740-2 and the associated default assumptions shall be used to calculate the concentration for direct contact with contaminated soil.
(I) Noncarcinogens. For noncarcinogenic toxic effects of hazardous substances due to soil ingestion, concentrations shall be determined using Equation 740-1. For petroleum mixtures and components of such mixtures, see (b)(iii)(B)(III) of this subsection.
[Equation 740-1]
Soil Cleanup Level
(mg/kg)
= RfD x ABW x UCF x HQ x AT
--------------------------------------------------------------------------------
SIR x AB1 x EF x ED
Where:
RfD = Reference dose as defined in
WAC 173-340-708(7) (mg/kg-day)
ABW = Average body weight over the exposure duration (16 kg)
UCF = Unit conversion factor (1,000,000 mg/kg)
SIR = Soil ingestion rate (200 mg/day)
AB1 = Gastrointestinal absorption fraction (1.0) (unitless)
EF = Exposure frequency (1.0) (unitless)
HQ = Hazard quotient (1) (unitless)
AT = Averaging time (6 years)
ED = Exposure duration (6 years)
(II) Carcinogens. For carcinogenic effects of hazardous substances due to soil ingestion, concentrations shall be determined using Equation 740-2. For petroleum mixtures and components of such mixtures, see (b)(iii)(B)(III) of this subsection.
[Equation 740-2]
Soil Cleanup Level
(mg/kg)
= RISK x ABW x AT x UCF
--------------------------------------------------------------------------------
CPF x SIR x AB1 x ED x EF
Where:
RISK = Acceptable cancer risk level (1 in 1,000,000) (unitless)
ABW = Average body weight over the exposure duration (16 kg)
AT = Averaging time (75 years)
UCF = Unit conversion factor (1,000,000 mg/kg)
CPF = Carcinogenic potency factor as defined in
WAC 173-340-708(8)
(kg-day/mg)
SIR = Soil ingestion rate (200 mg/day)
AB1 = Gastrointestinal absorption fraction (1.0) (unitless)
ED = Exposure duration (6 years)
EF = Exposure frequency (1.0) (unitless)
(III) Petroleum mixtures. For noncarcinogenic effects of petroleum mixtures, a total petroleum hydrocarbon cleanup level shall be calculated taking into account the additive effects of the petroleum fractions and volatile organic compounds substances present in the petroleum mixture. Equation 740-3 shall be used for this calculation. This equation takes into account concurrent exposure due to ingestion and dermal contact with petroleum contaminated soils. Cleanup levels for other noncarcinogens and known or suspected carcinogens within the petroleum mixture shall be calculated using Equations 740-4 and 740-5. See Table 830-1 for the analyses required for various petroleum products to use this method.
[Equation 740-3]
Where:
Csoil = TPH soil cleanup level (mg/kg)
HI = Hazard index (1) (unitless)
ABW = Average body weight over the exposure duration (16 kg)
AT = Averaging time (6 years)
EF = Exposure frequency (1.0) (unitless)
ED = Exposure duration (6 years)
SIR = Soil ingestion rate (200 mg/day)
AB1 = Gastrointestinal absorption fraction (1.0) (unitless)
F(i) = Fraction (by weight) of petroleum component (i) (unitless)
SA = Dermal surface area (2,200 cm2)
AF = Adherence factor (0.2 mg/cm2-day)
ABS = Dermal absorption fraction for petroleum component (i) (unitless). May use chemical-specific values or the following defaults:
? 0.0005 for volatile petroleum components with vapor press > = benzene
? 0.03 for volatile petroleum components with vapor press < benzene
? 0.1 for other petroleum components
RfDo(i) = Oral reference dose of petroleum component (i) as defined in WAC 173-340-708(7) (mg/kg-day)
RfDd(i) = Dermal reference dose for petroleum component (i) (mg/kg-day) derived by RfDo x GI
GI = Gastrointestinal absorption conversion factor (unitless). May use chemical-specific values or the following defaults:
? 0.8 for volatile petroleum components
? 0.5 for other petroleum components
n = The number of petroleum components (petroleum fractions plus volatile organic compounds with an RfD) present in the petroleum mixture. (See Table 830-1.)
(C) Soil vapors. The soil to vapor pathway shall be evaluated for volatile organic compounds whenever any of the following conditions exist:
(I) For gasoline range organics, whenever the total petroleum hydrocarbon (TPH) concentration is significantly higher than a concentration derived for protection of ground water for drinking water beneficial use under WAC 173-340-747(6) using the default assumptions;
(II) For diesel range organics, whenever the total petroleum hydrocarbon (TPH) concentration is greater than 10,000 mg/kg;
(III) For other volatile organic compounds, including petroleum components, whenever the concentration is significantly higher than a concentration derived for protection of ground water for drinking water beneficial use under WAC 173-340-747(4).
See subsection (3)(c)(iv)(B) of this section for methods that may be used to evaluate the soil to vapor pathway.
(c) Modified Method B soil cleanup levels.
(i) General. Modified Method B soil cleanup levels are standard Method B soil cleanup levels, modified with chemical-specific or site-specific data. When making these modifications, the resultant cleanup levels shall meet applicable state and federal laws, meet health risk levels for standard Method B soil cleanup levels, and be demonstrated to be environmentally protective using the procedures specified in WAC 173-340-7490 through 173-340-7494. Changes to exposure assumptions must comply with WAC 173-340-708(10).
(ii) Allowable modifications. The following modifications can be made to the default assumptions in the standard Method B equations to derive modified Method B soil cleanup levels:
(A) For the protection of ground water, see WAC 173-340-747;
(B) For soil ingestion, the gastrointestinal absorption fraction, may be modified if the requirements of WAC 173-340-702 (14), (15), (16), and 173-340-708(10) are met;
(C) For dermal contact, the adherence factor, dermal absorption fraction and gastrointestinal absorption conversion factor may be modified if the requirements of WAC 173-340-702 (14), (15), (16), and 173-340-708(10) are met;
(D) Toxicity equivalent factors, as described in WAC 173-340-708(8), may be used for assessing the potential carcinogenic risk of mixtures of chlorinated dibenzo-p-dioxins, chlorinated dibenzofurans and polycyclic aromatic hydrocarbons;
(E) The reference dose and cancer potency factor may be modified if the requirements in WAC 173-340-708 (7) and (8) are met; and
(F) Other modifications incorporating new science as provided for in WAC 173-340-702 (14), (15) and (16).
(iii) Dermal contact. For hazardous substances other than petroleum mixtures, dermal contact with the soil shall be evaluated whenever the proposed changes to Equations 740-1 or 740-2 would result in a significantly higher soil cleanup level than would be calculated without the proposed changes. When conducting this evaluation, the following equations and default assumptions shall be used.
(A) For noncarcinogens use Equation 740-4. This equation takes into account concurrent exposure due to ingestion and dermal contact with soil.
[Equation 740-4]
Where:
Csoil = Soil cleanup level (mg/kg)
HQ = Hazard quotient (unitless)
ABW = Average body weight over the exposure duration (16 kg)
AT = Averaging time (6 years)
EF = Exposure frequency (1.0) (unitless)
ED = Exposure duration (6 years)
SIR = Soil ingestion rate (200 mg/day)
AB1 = Gastrointestinal absorption fraction (1.0) (unitless)
SA = Dermal surface area (2,200 cm2)
AF = Adherence factor (0.2 mg/cm2-day)
ABS = Dermal absorption fraction (unitless).
May use chemical-specific values or the following defaults:
? 0.01 for inorganic hazardous substances
? 0.0005 for volatile organic compounds with vapor press > = benzene
? 0.03 for volatile organic compounds with vapor press < benzene
? 0.1 for other organic hazardous substances
RfDo = Oral reference dose as defined in WAC 173-340-708(7) (mg/kg-day)
RfDd = Dermal reference dose (mg/kg-day) derived by RfDo x GI
GI = Gastrointestinal absorption conversion factor (unitless).
May use chemical specific values or the following defaults:
? 0.2 for inorganic hazardous substances
? 0.8 for volatile organic compounds
? 0.5 for other organic hazardous substances
(B) For carcinogens use Equation 740-5. This equation takes into account concurrent exposure due to ingestion and dermal contact with soil.
[Equation 740-5]
Where:
Csoil = Soil cleanup level (mg/kg)
RISK = Acceptable cancer risk (1 in 1,000,000) (unitless)
ABW = Average body weight over the exposure duration (16 kg)
AT = Averaging time (75 years)
EF = Exposure frequency (1.0) (unitless)
ED = Exposure duration (6 years)
SIR = Soil ingestion rate (200 mg/day)
AB1 = Gastrointestinal absorption fraction (1.0) (unitless)
CPFo = Oral cancer potency factor as defined in WAC 173-340-708(8) (kg-day/mg)
CPFd = Dermal cancer potency factor (kg-day/mg) derived by CPFo/GI
GI = Gastrointestinal absorption conversion factor (unitless).
May use chemical-specific values or the following defaults:
? 0.2 for inorganic hazardous substances
? 0.8 for volatile organic compounds
? 0.5 for other organic hazardous substances
SA = Dermal surface area (2,200 cm2)
AF = Adherence factor (0.2 mg/cm2-day)
ABS = Dermal absorption fraction (unitless). May use chemical-specific values or the following defaults:
? 0.01 for inorganic hazardous substances
? 0.0005 for volatile organic compounds with vapor press > = benzene
? 0.03 for volatile organic compounds with vapor press < benzene
? 0.1 for other organic hazardous substances
(C) Modifications may be made to Equations 740-4 and 740-5 as provided for in subsection (3)(c)(ii) of this section.
(iv) Soil vapors.
(A) Applicability. The soil to vapor pathway shall be evaluated for volatile organic compounds whenever any of the following conditions exist:
(I) For other than petroleum hydrocarbon mixtures, the proposed changes to the standard Method B equations (Equations 740-1 and 740-2) or default values would result in a significantly higher soil cleanup level than would be calculated without the proposed changes;
(II) For petroleum hydrocarbon mixtures, the proposed changes to the standard Method B equations (Equations 740-3, 740-4 and 740-5) or default values would result in a significantly higher soil cleanup level than would be calculated without the proposed changes;
(III) For gasoline range organics, whenever the total petroleum hydrocarbon (TPH) concentration is significantly higher than a concentration derived for protection of ground water for drinking water beneficial use under WAC 173-340-747(6) using the default assumptions;
(IV) For diesel range organics, whenever the total petroleum hydrocarbon (TPH) concentration is greater than 10,000 mg/kg;
(V) For other volatile organic compounds, including petroleum components, whenever the concentration is significantly higher than a concentration derived for protection of ground water for drinking water beneficial use under WAC 173-340-747(4).
(B) Evaluation methods. Soil cleanup levels that are protective of the indoor and ambient air shall be determined on a site-specific basis. Soil cleanup levels may be evaluated as being protective of air pathways using any of the following methods:
(I) Measurements of the soil vapor concentrations, using methods approved by the department, demonstrating vapors in the soil would not exceed air cleanup levels established under WAC 173-340-750.
(II) Measurements of ambient air concentrations and/or indoor air vapor concentrations throughout buildings, using methods approved by the department, demonstrating air does not exceed cleanup levels established under WAC 173-340-750. Such measurements must be representative of current and future site conditions when vapors are likely to enter and accumulate in structures. Measurement of ambient air may be excluded if it can be shown that indoor air is the most protective point of exposure.
(III) Use of modeling methods approved by the department to demonstrate the air cleanup standards established under WAC 173-340-750 will not be exceeded. When this method is used, the department may require soil vapor and/or air monitoring to be conducted to verify the calculations and compliance with air cleanup standards.
(IV) Other methods as approved by the department demonstrating the air cleanup standards established under WAC 173-340-750 will not be exceeded.
(d) Using modified Method B to evaluate soil remediation levels. In addition to the adjustments allowed under subsection (3)(c) of this section, adjustments to the reasonable maximum exposure scenario or default exposure assumptions are allowed when using a quantitative site-specific risk assessment to evaluate the protectiveness of a remedy. See WAC 173-340-355, 173-340-357, and 173-340-708 (3)(d) and (10)(b).
(4) Method C soil cleanup levels. This section does not provide procedures for establishing Method C soil cleanup levels. Except for qualifying industrial properties, Method A and Method B, as described in this section, are the only methods available for establishing soil cleanup levels at sites. See WAC 173-340-745 for use of Method C soil cleanup levels at qualifying industrial properties. See also WAC 173-340-357 and 173-340-708 (3)(d) for how land use may be considered when selecting a cleanup action at a site.
(5) Adjustments to cleanup levels.
(a) Total site risk adjustments. Soil cleanup levels for individual hazardous substances developed in accordance with subsection (3) of this section, including cleanup levels based on applicable state and federal laws, shall be adjusted downward to take into account exposure to multiple hazardous substances and/or exposure resulting from more than one pathway of exposure. These adjustments need to be made only if, without these adjustments, the hazard index would exceed one (1) or the total excess cancer risk would exceed one in one hundred thousand (1 x 10-5). These adjustments shall be made in accordance with the procedures specified in WAC 173-340-708 (5) and (6). In making these adjustments, the hazard index shall not exceed one (1) and the total excess cancer risk shall not exceed one in one hundred thousand (1 x 10-5).
(b) Adjustments to applicable state and federal laws. Where a cleanup level developed under subsection (2) or (3) of this section is based on an applicable state or federal law and the level of risk upon which the standard is based exceeds an excess cancer risk of one in one hundred thousand (1 x 10-5) or a hazard index of one (1), the cleanup level must be adjusted downward so that the total excess cancer risk does not exceed one in one hundred thousand (1 x 10-5) and the hazard index does not exceed one (1) at the site.
(c) Natural background and PQL considerations. Cleanup levels determined under subsection (2) or (3) of this section, including cleanup levels adjusted under subsection (5)(a) and (b) of this section, shall not be set at levels below the practical quantitation limit or natural background, whichever is higher. See WAC 173-340-707 and 173-340-709 for additional requirements pertaining to practical quantitation limits and natural background.
(6) Point of compliance.
(a) The point of compliance is the point or points where the soil cleanup levels established under subsection (2) or (3) of this section shall be attained.
(b) For soil cleanup levels based on the protection of ground water, the point of compliance shall be established in the soils throughout the site.
(c) For soil cleanup levels based on protection from vapors, the point of compliance shall beestablished in the soils throughout the site from the ground surface to the uppermost ground water saturated zone (e.g., from the ground surface to the uppermost water table). (continued)