[26 Pa.B. 3985]
[Continued from previous Web Page] (d) If soil is determined to be a media of concern, the site characterization shall determine the relative location of soil samples necessary to characterize the horizontal and vertical extent of contamination based on factors such as hydraulic conductivity of the soils, heterogeneity of the soils and the nature of the contaminants. The horizontal and vertical extent of soil with concentrations of a regulated substances above the selected standard shall be defined by an appropriate number of samples inside and outside of the area that exceeds the standard. Soil samples from the area with the anticipated highest levels of contamination shall be obtained, as appropriate, to determine the applicability of the proposed remedial action or handling and disposal requirements, or both, for that soil during remediation.
(e) If groundwater is determined to be a media of concern, the site characterization shall characterize the effects of a release on groundwater to adequately determine how naturally occurring physical and geochemical characteristics define the movement of groundwater and contaminants beneath the surface, including the delineation of the position of aquifers, as well as geologic units which inhibit groundwater flow. The site characterization shall meet the following conditions:
(1) If appropriate, the characterization shall consider the heterogeneity and anisotropy of aquifer materials based on hydraulic conductivity values (measured or published), and the effect of local and regional groundwater flow directions and any influence from pumping wells.
(2) Defining the horizontal extent of concentrations of a regulated substances above the standard shall require more than one round of groundwater sampling from properly constructed and developed monitoring wells taken with a sufficient number of days apart to yield independently valid results.
(3) When characterizing the vertical extent of groundwater contamination, the person shall perform more than one round of groundwater sampling and shall consider the specific gravity of the regulated substances identified in the groundwater in the site, and the potential for naturally occurring or induced downward vertical hydraulic gradients.
(4) When characterizing the vertical extent of groundwater contamination, properly constructed monitoring wells or nested monitoring wells should be utilized to focus groundwater sampling in zones of potential contaminant accumulation--that is, directly above a confining layer--and sampling shall be taken with a sufficient number of days apart to yield independently valid results.
(f) Final reports for the background standard shall include the following additional information:
(1) Descriptions of treatment, removal or decontamination procedures performed in remediation.
(2) Descriptions of the sampling methodology and analytical results, including the appropriate statistical methodologies, which pertain to whether the remediation has attained the selected standard, following the requirements of Subchapter G (relating to demonstration of attainment).
(3) Documentation of compliance with postremediation care requirements, if they are needed to maintain the selected standard.
(4) All sampling data.
(5) If background was established based on a site characterization, a summary of sampling methodology and analytical results that relate to the determination of the background concentration. The summary shall contain the following:
(i) For soil, the final report shall identify the background region within which all background samples were collected.
(ii) For groundwater, the final report shall identify background wells.
(6) Documentation that background areas for soil meet the following criteria:
(i) The background region and background areas shall be free of contamination from any release at the site.
(ii) The statistical distribution and comparison parameters used to demonstrate background shall be the same in establishing background levels and in establishing distribution and parameters in the cleanup units. Sampling at the background area and the cleanup unit shall be comparable and random.
(iii) A background area selected for comparison with a given cleanup unit may not differ significantly from that cleanup unit in physical, chemical or biological characteristics that might cause measurements in the background area and the cleanup unit to differ.
(7) Documentation that background groundwater concentrations have been determined at hydrogeologically upgradient points that characterize the groundwater flow onto the site that are not affected by any release at the property.
(g) If engineering controls are needed to attain or maintain a standard or if institutional controls are needed to maintain a standard, a post remediation care plan shall be documented in the final report. The plan shall include the following:
(1) Reporting of any instance of nonattainment.
(2) Reporting of measures to correct nonattainment conditions.
(3) Periodic reporting of monitoring, sampling and analysis as required by the Department.
(4) Maintenance of records at the property where the remediation is being conducted for monitoring, sampling and analysis.
(5) A schedule for operation and maintenance of the controls and submission of proposed changes.
Subchapter C. STATEWIDE HEALTH STANDARDS Sec.
250.301. Scope. 250.302. Point of compliance. 250.303. MSCs for groundwater. 250.304. MSCs for soil. 250.305. Ingestion numeric value. 250.306. Inhalation numeric values. 250.307. Soil to groundwater pathway numeric values. 250.308. Radionuclide numeric values. 250.309. Minimum threshold MSCs. 250.310. Evaluation of ecological receptors. 250.311. Final report. § 250.301. Scope.
(a) This subchapter sets forth generic statewide health standards as one of three remediation standards that a person may select. The statewide health standards are concentrations of regulated substances associated with a specific environmental medium, and are designated as the MSCs. The values used to determine the MSCs are contained in Appendix A, Tables 1, 2 and 5 and are the concentrations of regulated substances that shall be met to demonstrate attainment of a Statewide health standard. Appendix A, Table 3 presents the toxicological and physical parameters used to calculate the MSCs in Appendix A, Tables 1 and 2.
(b) This subchapter sets forth minimum threshold MSCs for soil and groundwater that shall be met to demonstrate attainment with regulated substances in Appendix A, Table 4. Minimum threshold MSCs are standards developed for regulated substances for which no chemical-specific toxicological data exists.
§ 250.302. Point of compliance.
(a) For regulated substances in groundwater, the MSC as determined in § 250.303 (relating to MSCs for groundwater) is the Statewide health standard that shall be met at the point of compliance.
(b) For attainment of the Statewide health standard for ingestion and inhalation, the point of compliance is at and beyond the property boundary that existed at the time the contamination is discovered or a point beyond the property boundary that the Department may, in writing, determine to be appropriate under the following situations:
(1) The original contamination source was at the property boundary.
(2) Structures are located on the property boundary which prohibit internal or external access for a drill rig.
(3) The property is a small parcel of land with limited space for onsite monitoring wells.
(4) It is not physically possible to monitor groundwater quality at the property boundary.
(5) The downgradient property was owned by the same party at the time the contamination was discovered and the use of the groundwater on the downgradient property can be controlled to prevent unacceptable exposure.
(6) Where regulated substances are only secondary contaminants for which a secondary MCL exists.
(c) For attainment of the Statewide health standard for soil, the MSC as determined in § 250.304 (relating to MSCs for soil) shall be met at the specified depth.
(d) For the discharges of regulated substances to surface water:
(1) For point source discharges to surface water, the point of compliance is measured at the point of discharge in accordance with limits specified in the NPDES permit.
(2) For purposes of determining compliance with surface water quality standards from a diffuse groundwater discharge, the person shall estimate the expected instream regulated substance concentrations, using mass balance techniques for groundwater/surface water mixing at design flow conditions. If the results indicate that surface water quality standards are being achieved, no action is required. If results indicate that surface water quality standards are not being achieved, further remedial action will be required. In the case of special protection waters, point source and nonpoint discharges shall meet the applicable regulations and achieve water quality that does not preclude uses existing prior to the contamination from this source.
(3) For purposes of complying with surface water quality standards in a spring, the point of compliance is the point of discharge to the ground surface.
(e) For the emission of regulated substances to outdoor air, the point of compliance for any applicable air quality standard shall be as specified in the air quality regulations.
§ 250.303. MSCs for groundwater.
(a) A person shall implement a remedy under the Statewide health standard that is protective of human health and the environment.
(b) The MSCs for regulated substances in groundwater in aquifers used or currently planned to be used for drinking water or for agricultural purposes are presented in Appendix A, Tables 1 and 5. The methodology for calculating MSCs in groundwater is detailed in subsections (c) and (d).
(c) The MSCs for regulated substances contained in groundwater in aquifers used or currently planned to be used for drinking water or for agricultural purposes is the MCL as established by the Department or the EPA (U. S. EPA, 1996. Drinking Water Regulations and Health Advisories. Office of Water. EPA 822-R-96-001). For a regulated substance where no MCL has been established, the MSC is the lifetime health advisory level (HAL) for that compound. For a regulated substance where neither an MCL nor a lifetime HAL is established by the EPA, the MSC is the lowest concentration calculated using the appropriate residential and nonresidential exposure assumptions and the equations in §§ 250.305 and 250.306 (relating to ingestion numeric values; and inhalation numeric values).
(d) If the groundwater at the site has naturally occurring background total dissolved solids concentrations greater than 2,500 milligrams per liter, the Statewide health standard for a regulated substance dissolved in the groundwater may be adjusted by multiplying the MSC for groundwater in aquifers by 100. The adjusted Statewide health standard shall then be used in calculating the soil to groundwater pathway numeric value as specified in § 250.307 (relating to soil to groundwater pathway numeric values).
(e) Volatilization from groundwater through soils into indoor air shall be evaluated and abated through the use of the background standard or the site-specific standard if the following apply:
(i) Carbon tetrachloride, 1,1 dichloroethene, 1,2 dichloroethane, benzene, chloroform or vinyl chloride are present in the groundwater.
(ii) Groundwater is present at depths less than 15 feet from the ground surface.
§ 250.304. MSCs for soil.
(a) A person shall implement a remedy under the Statewide health standard that is protective of human health and the environment.
(b) The MSCs for regulated substances in soil are presented in Appendix A, Tables 2 and 5. The methodology for calculating MSCs in soil is detailed in subsections (c) and (d) and is further limited to not exceed the physical capacity of the soil to contain a regulated substance. This physical limitation is based on an assumed porosity of .35, an assumed dry bulk density of soil of 1.8 kilograms per liter and an assumed density of a regulated substance of 1.0 kilograms per liter and is calculated according to the following equation:
(c) For the residential standard, the MSC for regulated substances contained in soil is the lowest one of the following:
(1) The ingestion numeric value within a depth of up to 15 feet from the existing ground surface as determined by the methodology in § 250.305 (relating to ingestion numeric values), using the appropriate default residential exposure assumptions contained in § 250.305(e).
(2) The inhalation numeric value within a depth of up to 15 feet in soil from the existing ground surface, which considers volatilization into the outdoor air and inhalation of particulates, as determined by the methodology in § 250.306 (relating to inhalation numeric values), using the appropriate default residential exposure assumptions contained in § 250.306(d).
(3) The soil-to-groundwater pathway numeric value throughout the soil column as determined by the methodology in § 250.307 (relating to soil to groundwater pathway numeric values).
(d) For the nonresidential standard, the MSC for regulated substances contained in soil is one of the following:
(1) For soils within a depth of up to 2 feet from the existing ground surface, the MSC is the lowest one of the following:
(i) The ingestion numeric value as determined by the methodology in § 250.305, using the appropriate default nonresidential exposure assumptions contained in § 250.305(e).
(ii) The inhalation numeric value which is the lower of the values for volatilization into the outdoor air and the inhalation of particulates, as determined by the methodology in § 250.306, using the appropriate default non-residential exposure assumptions contained in § 250.306(d).
(2) For soils at depths greater than 2 feet through 15 feet from the existing ground surface, the MSC is the lowest of one of the following:
(i) The inhalation numeric value which considers volatilization to the outdoor air, as determined by the methodology in § 250.306, using the appropriate default nonresidential exposure assumptions contained in § 250.306(d), and using a TF based upon the calculated emission rate from subsurface soil as specified in the method of Jury, et al. 1990. Water Resources Research, Vol. 26, No. 1, pp. 13-20.
(ii) The soil-to-groundwater pathway numeric value throughout the soil column as determined by the methodology in § 250.307.
(e) A person conducting a remediation of soils contaminated with a substance having only a secondary MCL will not be required to comply with the soil to groundwater standard for those substances to protect groundwater in aquifers for drinking water.
(f) For the residential standard, the MSC for regulated substances which are radionuclides is the lowest one of the following:
(1) The ingestion numeric value within a depth of up to 15 feet from the existing ground surface as determined by the methodology in § 250.308 (relating to radionuclide numeric values), using the appropriate default residential exposure assumptions contained in § 250.308(a).
(2) The inhalation numeric value within a depth of up to 15 feet from the existing ground surface, which considers volatilization into the outdoor air and inhalation of particulates, as determined by the methodology in § 250.308(b) and (c), using the appropriate default residential exposure assumptions contained in § 250.308(e).
(3) The direct exposure pathway numeric value as determined by the methodology in § 250.308(d).
(4) The soil-to-groundwater pathway numeric value throughout the soil column as determined by the methodology in § 250.307.
(g) For the nonresidential standard, the MSC for regulated substances which are radionuclides is the lowest one of the following:
(1) The ingestion numeric value within a depth of up to 15 feet from the existing ground surface as determined by the methodology in § 250.308(a), using the appropriate default nonresidential exposure assumptions contained in § 250.308(e).
(2) The inhalation numeric value within a depth of up to 15 feet from the existing ground surface, which considers volatilization into the outdoor air and inhalation of particulates, as determined by the methodology in § 250.308(b) and (c), using the appropriate default nonresidential exposure assumptions contained in § 250.308(e).
(3) The direct exposure pathway numeric value as determined by the methodology in § 250.308(d).
(4) The soil-to-groundwater pathway numeric value throughout the soil column as determined by the methodology in § 250.307.
§ 250.305. Ingestion numeric values.
(a) For a regulated substance which is a systemic toxicant, the ingestion numeric value for that substance was calculated using the appropriate residential or nonresidential exposure assumptions from subsection (e) according to the following equation:
(b) For a regulated substance which is a carcinogen, the ingestion numeric value for that substance was calculated using the appropriate residential or nonresidential exposure assumptions from subsection (e) according to the following equation:
(c) For a regulated substance that has both an oral reference dose and an oral cancer slope factor, the ingestion numeric value is the lower of the two numbers as calculated by the equations in subsections (a) and (b).
(d) The numeric values in subsections (a)--(c) can be used only if there is no nonaqueous phase liquid.
(e) The default exposure assumptions used to calculate the ingestion numeric values are as follows:
Residential Nonresidential Term Systemic1 Carcinogens2 (Onsite Worker) THQ Target Hazard Quotient 1 N/A 1 RfDo Oral Reference Dose
(mg/kg-day)Chemical-specific N/A Chemical-specific BW Body Weight (kg)
Soil
Groundwater
15
70N/A
70
70ATnc Averaging Time for
systemic toxicants (yr)
Soil
Groundwater
6
30
N/A
N/A
25
25Abs Absorption (unitless)3 1 1 1 EF Exposure Frequency
(d/yr)
Soil
Groundwater
250
350
250
350
180
250ED Exposure Duration (yr)
Soil
Groundwater
6
30
N/A
N/A
25
25IngR Ingestion Rate
Soil (mg/day)
GW (L/day)
100
2
N/A
N/A
50
1CF Conversion Factor
Soil (kg/mg)
GW (unitless)
1 x 10-6
1
1 x 10-6
1
1 x 10-6
1TR Target Risk N/A 1 x 10-5 1 x 10-5 CSFo Oral Cancer Slope Factor
(mg/kg-day)-1N/A Chemical-specific Chemical-specific ATc Averaging Time for carcinogens (yr) N/A 70 70 Ifadj4 Ingestion Factor
Soil (mg-yr/kg-day)
GW (L-yr/kg-day)N/A
57.1
1.1
17.9
0.4Notes:
1 Residential exposure to noncarcinogens is based on childhood (ages 1-6) exposure for soil, and adult exposure for groundwater, consistent with USEPA (1991).
2 Residential exposure to carcinogens is based on combined childhood and adult exposure.
3 The oral absorption factor takes into account absorption and bioavailability. In cases where the oral RfD or CSF is based on administered oral dose, the absorption factor would be limited to bioavailability. The default value is 1.
4 The Ingestion Factor for the residential scenario is calculated using the equation Ifadj = EDc x IRc /BWc + EDa x IRa /Bwa, where EDc = 6 yr, IRc =100 mg/day for soils and 1 L/day for groundwater, BWc = 15 kg, EDa = 24 yr, IRa =50 mg/day for soils and 2 L/day for groundwater, and BWa = 70 kg. The ingestion factor for the nonresidential scenario is calculated using the equation Ifadj = EDxIR/BW, where ED = 25 yr, IR = 50 mg/day for soils and 1L/day for groundwater, and BW = 70 kg.
(f) The residential ingestion numeric value for lead in soil was developed using the Uptake Biokinetic (UBK) Model for Lead (version 0.4) developed by the EPA (U. S. Environmental Protection Agency. (1990). Uptake Biokinetic (UBK) Model for Lead (version 0.4). U. S. EPA/ECAO. August 1990), in lieu of the algorithms presented in subsections (a) and (b). Default input values are identified in Appendix A, Table 6. Because the UBK model is applicable only to children, the nonresidential ingestion numeric value was calculated according to the method developed by the Society for Environmental Geochemistry and Health (Wixson, B.G. (1991)). The Society for Environmental Geochemistry and Health (SEGH) Task Force Approach to the Assessment of Lead in Soil. Trace Substances in Environmental Health. 11-20), using the following equations:
Table 6 identifies each of the variables in this equation.
§ 250.306. Inhalation numeric values.
(a) For a regulated substance which is a systemic toxicant, the following applies:
(1) For a volatile compound, the numeric value for inhalation from soil shall be calculated using the appropriate residential or nonresidential exposure assumptions from subsection (d) according to the following equation using TF for volatiles:
(2) For a regulated substance attached to particulates, the numeric value for inhalation from soil was calculated using the appropriate residential or nonresidential exposure assumptions from subsection (d) according to the equation in paragraph (1) using TF for particulates.
(b) For a regulated substance which is a carcinogen, the following apply:
(1) For a volatile compound, the numeric value for inhalation from soil was calculated using the appropriate residential or nonresidential exposure assumptions from subsection (d) according to the following equation using TF for volatiles:
(2) For a regulated substance attached to particulates, the numeric value for inhalation from soil was calculated using the appropriate residential or nonresidential exposure assumptions from subsection (d) according to the equation in paragraph (1) using TF for particulates.
(c) For a regulated substance which is both a systemic toxicant and a carcinogen, the inhalation numeric value is the lower of the two numbers as calculated by the equations in subsections (a) and (b).
(d) The default exposure assumptions used to calculate the inhalation numeric values for soil are as follows:
Residential Nonresidential Term Systemic1 Carcinogens2 (Onsite Worker) THQ Target Hazard Quotient 1 N/A 1 RfDi Inhal. Reference Dose
(mg/kg-day)Chemical-specific N/A Chemical-specific BW Body Weight (kg) 70 N/A 70 ATnc Averaging Time for systemic toxicants (yr) 30 N/A 25 TF Transport Factor
(mg/kg)/(mg/m3)
Volatilization3
Particulate4
Chemical-specific
1 x 1010
Chemical-specific
1 x 1010
Chemical-specific
1 x 1010Abs Absorption (unitless)5 1 1 1 ET Exposure Time (hr/day) 24 24 8 EF Exposure Frequency6 (d/yr) 250 250 180 ED Exposure Duration (yr) 30 N/A 25 IR Inhalation Rate (m3/hr) 0.83 N/A 1.25 TR Target Risk N/A 1 x 10-5 1 x 10-5 CSFi Inhalation Cancer Slope
Factor (mg/kg-day)-1N/A Chemical-specific Chemical-specific ATc Averaging Time for carcinogens (yr) N/A 70 70 Ifadj Inhalation Factor7
(m3-yr / kg-hr)N/A 0.5 0.4 Notes: Modified from USEPA Region III Risk-based Concentration Table, dated October 20, 1995.
N/A = Not Appplicable
1 Residential exposure to systemic toxicants is based on adult exposure, consistent with USEPA (1991).
2 Residential exposure to carcinogens is based on combined child and adult exposure.
3 Volatilization TF is calculated using TF=(ER x DF)-1, where DF =12 (mg/m3) / (m2-sec). See soil depth-specific algorithm for the calculation of ER.
4 Particulate TF was calculated using TF=(ER x DF)-1, where ER = 8.25 x 10-12 (mg/m2-sec)/ (mg/kg) and DF = 12 (mg/m3)/(mg/m2-sec).
5 In cases where the inhalation RfD or CSF is based on absorbed dose, this factor can be applied in the exposure algorithm. The default value is 1.
6 Assumes approximately 100 days/yr with the ground being frozen. Exposure to surficial soils when the ground is frozen is considered de minimis. The nonresidential exposure frequency is defined as 5/7 x 250 days/yr.
7 The inhalation factor for the residential scenario is calculated using the equation IFadj = EDc x IRc /BWc + EDa x IRa /Bwa, where EDc = 6 yr, IRc =0.5 m3/hr, BWc = 15 kg, EDa = 24 yr, IRa =0.83 m3/hr, and BWa = 70 kg. The inhalation factor for the nonresidential scenario is calculated using the equation IFadj = ED x IR / BW , where ED = 25 yr, IR =1.25 m3/hr and BW = 70 kg.
(e) For the inhalation numeric values in subsections (a) and (b), the TF was calculated by the following equation:
TF = (ERxDF)-1The Dispersion Factor (DF) value of 12 (mg/m3)/(mg/m2/sec) is taken from the default value in the EPA Draft Soil Screening Guidance (U. S. EPA, 1994. Technical Background Document for Soil Screening Guidance. Review Draft. Office of Emergency and Remedial Response. EPA-540/R-94/106) and the Emission Rate (ER) is calculated by the following equations (from Jury et al. 1990. Water Resources Research, Vol. 26. No. 1. pp. 13-20):
(h) The default exposure assumptions used to calculate the inhalation numeric values for the inhalation of volatiles from groundwater are as follows:
Residential Nonresidential Term Systemic1 Carcinogens2 (Onsite Worker) THQ Target Hazard Quotient 1 N/A 1 RfDi Inhal. Reference Dose (mg/kg-day) Chemical-specific N/A Chemical-specific BW Body Weight (kg) 70 N/A 70 ATnc Averaging Time for systemic toxicants (yr) 30 N/A 25 Abs Absorption (unitless)3 1 1 1 ET Exposure Time (hr/day) 24 24 8 EF Exposure Frequency6 (d/yr) 350 350 250 ED Exposure Duration (yr) 30 N/A 25 IR Inhalation Rate (m3/hr) 0.625 N/A 1.25 TF Transfer Factor (L/m3)4 0.5 0.5 0.5 TR Target Risk N/A 1 x 10-5 1 x 10-5 CSFi Inhalation Cancer Slope Factor (mg/kg-day)-1 N/A Chemical-specific Chemical-specific ATc Averaging Time for carcinogens (yr) N/A 70 70 Ifadj Inhalation Factor5
(m3-yr / kg-hr)N/A 0.4 0.4 Notes: Modified from USEPA Region III Risk-based Concentration Table, dated October 20, 1995.
N/A = Not Applicable
1 Residential exposure to systemic toxicants is based on adult exposure, consistent with USEPA (1991).
2 Residential exposure to carcinogens is based on combined child and adult exposure.
3 In cases where the inhalation RfD or CSF is based on absorbed dose, this factor can be applied in the exposure algorithm.
4 Default TF is as presented in USEPA's RAGS, Part B.
5 The inhalation factor for the residential scenario is calculated using the equation IFadj = EDc x IRc /BWc + EDa x IRa /Bwa, where EDc = 6 yr, IRc =0.5 m3/hr, BWc = 15 kg, EDa = 24 yr, IRa =0.625 m3/hr, and BWa = 70 kg. The inhalation factor for the nonresidential scenario is calculated using the equation IFadj = ED x IR / BW , where ED = 25 yr, IR =1.25 m3/hr and BW = 70 kg.
§ 250.307. Soil to groundwater pathway numeric values.
(a) A person may use the soil-to-groundwater pathway numeric values listed in Appendix A, Table 2, as developed using the methods contained in paragraph (1) or (2), or may use a concentration in soil at the site which does not produce a leachate in excess of the MSC for groundwater contained in Appendix A, Table 1, when subjected to the Synthetic Precipitation Leaching Procedure (Method 1312 of SW-846, Test Methods for Evaluating Solid Waste, promulgated by the U. S. EPA).
(1) A value which is 100 times the MSC for groundwater, expressed as milligrams per kilogram of soil.
(2) For organic compounds, a generic value determined not to produce a concentration in groundwater in the aquifer in excess of the MSC for groundwater as calculated by the equation in paragraph (3).
(i) For unsaturated soil, the generic value shall be calculated by the equation in paragraph (3).
(ii) For saturated soil, the standard is 1/10th of the generic value calculated by the equation in paragraph (3).
(3) The equation referenced in paragraph (2) is the following:
where: MSCs (mg/kg) = the generic value for a regulated substance in soil
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