Subchapter C. STATEWIDE HEALTH STANDARDS

 (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—4 and 6 and are the concentrations of regulated substances that shall be met to demonstrate attainment of a Statewide health standard. Appendix A, Table 5 presents the toxicological and physical parameters used to calculate the MSCs in Appendix A, Tables 1—4.

 (b)  This subchapter sets forth minimum threshold MSCs for soil and groundwater that shall be met to demonstrate attainment of the Statewide health standards for regulated substances in Appendix A, Table 6. Minimum threshold MSCs are standards developed for regulated substances for which no chemical-specific toxicological data exist.

 (a)  For attainment of the Statewide health standard for groundwater, the point of compliance is the property boundary that existed at the time the contamination was discovered. Statewide health standards shall be attained at and beyond the point of compliance. The Department may determine, in writing, a point of compliance beyond the property boundary to be appropriate if one of the following situations is demonstrated:

   (1)  Structures are located on the property boundary which prohibit internal or external access for a drill rig.

   (2)  The property is a small parcel of land with limited space for onsite monitoring wells.

   (3)  It is not physically possible to monitor groundwater quality at the property boundary.

   (4)  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.

   (5)  For measuring compliance with the groundwater MSCs that apply to secondary contaminants.

 (b)  For attainment of the Statewide health standard for soil, the MSC as determined in §  250.305 (relating to MSCs for soil) shall be met at the specified depth.

 (c)  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.

 (a)  With the exception of seasonal, localized and hydrologically isolated perched systems under a property, all geologic formations or parts or groups of formations in this Commonwealth which are saturated are presumed to be aquifers for the purpose of applying the Statewide health standards. The term includes saturated residuum such as saprolite and other weathered rock strata or intervals developed from underlying bedrock and other saturated deposits overlying these formations to which the geologic formations are hydrologically connected.

 (b)  All groundwater in aquifers is presumed to be used or currently planned for use, unless determined otherwise by the Department under this section.

   (1)  The Department may determine, in writing, based on a demonstration by the person remediating a site identified in an NIR, that groundwater is not used or currently planned to be used, if:

     (i)   The public participation requirements of §  250.5 (relating to public notice by applicant) are met.

     (ii)   The requirements in subsection (c) are met within the site on the property and within a radius of 1,000 feet downgradient of the points of compliance plus any additional areas to which the contamination has migrated and might reasonably migrate at concentrations that exceed the MSC for groundwater used or currently planned to be used.

   (2)  Methods appropriate for determining current or currently planned future use may include door-to-door surveys, verifying community water system billing records and interviewing community water system suppliers with regard to their currently planned future groundwater use.

 (c)  The following requirements shall be met within the area described in subsection (b):

   (1)  No groundwater derived from wells or springs is used for drinking water or agricultural purposes.

   (2)  All downgradient properties are connected to a community water system.

   (3)  The area described in subsection (b) does not intersect a radius of 1/2 mile from a community water supply well source or does not intersect an area designated by the Department as a zone 2 wellhead protection area under Chapter 109 (relating to safe drinking water).

   (4)  At the time the nonuse aquifer determination request under subsection (b) is submitted to the Department, there are no existing documents developed by political subdivisions or community water system suppliers detailing the implementation of groundwater resources development (that is, no currently planned future uses) in the area specified in subsection (b)(1)(ii).

 (d)  If the Department determines that groundwater is not used or currently planned to be used, the following requirements apply within the area identified in subsection (b):

   (1)  The requirements in §  250.309 (relating to MSCs for surface water).

   (2)  The ecological screening process identified in §  250.311 (relating to evaluation of ecological receptors).

   (3)  The remediator shall establish institutional controls to maintain the integrity of the nonuse aquifer determination, or include a postremediation care plan in the final report detailing the process of routinely assessing and reporting to the Department compliance with subsection (c).

     (i)   Postremediation care plan provisions shall be acknowledged within the deed to the remediated property upon transfer of ownership to insure compliance with subsection (c).

     (ii)   Postremediation assessment and reporting requirements shall continue until the property owner can demonstrate that the MSC for groundwater in aquifers used or currently planned for use is not exceeded at the point of compliance, and fate and transport analysis shows that the MSC will not be exceeded at that point in the future.

 (e)  The MSCs for groundwater in an aquifer that is not used or currently planned for use, under §  250.304(d) (relating to MSCs for groundwater), shall be met at the points of compliance identified in §  250.302 (relating to point of compliance)

 (f)  A nonuse aquifer areawide certification obtained under this subsection may be used by the remediator to demonstrate that the requirements of subsection (c) are met.

   (1)  With or without the presence of an associated NIR, the Department may determine, in writing, based on a demonstration by a municipal authority or political subdivision, that groundwater is not used or currently planned to be used in a specific geographic area, if the following conditions exist:

     (i)   The municipal authority or political subdivision demonstrates that the requirements of subsection (c) are met in the specific geographic area.

     (ii)   Municipal ordinances are in effect that prohibit the use of groundwater from wells or springs for drinking water or agricultural purposes.

     (iii)   Municipal ordinances are in effect that require all water users to connect to a community water supply system.

   (2)  If the municipal ordinances relied upon to make the demonstration in paragraph (1) are amended or repealed, the political subdivision or municipal authority who requested the areawide designation shall notify the Department in writing within 30 days of the effective date of the amendment or repeal.

   The provisions of this §  250.303 amended November 23, 2001, effective November 24, 2001, 31 Pa.B. 6395. Immediately preceding text appears at serial pages (233650) to (233651).

 (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 are presented in Appendix A, Tables 1 and 2. The methodology used by the Department for calculating MSCs in groundwater is detailed in subsections (c)—(f).

 (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, the MSC is the lowest concentration calculated using the appropriate residential and nonresidential exposure assumptions and the equations in § §  250.306 and 250.307 (relating to ingestion numeric values; and inhalation numeric values).

 (d)  For regulated substances contained in aquifers not used or currently planned to be used, the MSCs in Appendix A, Tables 1 and 2 are calculated by the following:

   (1)  For volatile organic regulated substances with an attenuation factor of less than 20, as calculated by the methodology in paragraph (7), ten times the appropriate residential or nonresidential MSC for groundwater in aquifers used or currently planned to be used containing less than 2,500 mg/l total dissolved solids.

   (2)  For volatile organic regulated substances with an attenuation factor of greater than or equal to 20, as calculated by the methodology in paragraph (7), 100 times the appropriate residential or nonresidential MSC for groundwater in aquifers used or currently planned to be used containing less than 2,500 mg/l total dissolved solids.

   (3)  For semivolatile organic and inorganic regulated substances, regardless of the attenuation factor, 1,000 times the appropriate residential or nonresidential MSC for groundwater in aquifers used or currently planned to be used containing less than 2,500 mg/l total dissolved solids.

   (4)  For benzene, 100 times the appropriate residential or nonresidential MSC for groundwater in aquifers used or currently planned to be used containing less than 2,500 mg/l total dissolved solids.

   (5)  For regulated substances with no calculated attenuation factor because of a lack of data in Howard, P. H., R. S. Boethling, W. F. Jarais, W. M. Meylan and E. M. Michalenko. 1991. Handbook of Environmental Degradation Rates. Lewis Publishers, Inc., Chelsea, MI., the appropriate residential or nonresidential MSC for groundwater in aquifers used or currently planned to be used containing less than 2,500 mg/l total dissolved solids.

   (6)  For minimum threshold MSCs, 5 micrograms per liter in groundwater shall be used.

   (7)  The attenuation factor (AF) for an organic regulated substance shall be calculated according to the following formula:

 AF = K x KOC

 Where:

 K = degradation coefficient = 0.693

                T_1/2

 T1/2—half-life of organic regulated substance in groundwater as reported in Howard, P. H., R. S. Boethling, W. F. Jarais, W. M. Meylan and E. M. Michalenko, 1991. Handbook of Environmental Degradation Rates. Lewis Publishers, Inc., Chelsea, MI.

 KOC—organic carbon partitioning coefficient (See Appendix A Table 5).

 (e)  If the groundwater in aquifers used or currently planned for use 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 §  250.308 (relating to soil to groundwater pathway numeric values).

 (f)  In addition to the requirements in this section, the MSCs are further limited by solubility as identified in Appendix A, Table 5. The solubility limits are derived from the references in subsection (g), which are keyed to the numbers in Table 5. The following procedure was used to determine the appropriate solubility value for each regulated substance: where multiple sources are cited in Table 5, the value for the solubility limit is the median of the values in the indicated references.

   (1)  Using the hierarchy established in subsection (g), the first two references were consulted. If the solubility values agreed within 5%, the selected value is the lower of the two values.

   (2)  If the values in step (1) did not agree within 5%, the next references in order were consulted until two values that did agree within 5% were found. The selected value is then the median of all the values consulted.

   (3)  If none of the values in all of the references in subsection (g) agreed within 5%, the selected value is the median of all values in all references.

 (g)  The references referred to in subsection (f) are:

   (1)  Lide, D. R., ed. 1996. CRC Handbook of Chemistry and Physics, 77th Edition. CRC Press.

   (2)  Budavari, S., ed. 1996. The Merck Index, 12th Ed. Merck and Co.

   (3)  Perry, R. H., et al. 1997. Perry’s Chemical Engineer’s Handbook, 7th ed. McGraw-Hill, New York.

   (4)  Howard, P. H. 1991. Handbook of Environmental Fate and Exposure Data for Organic Chemicals. Vol. III Pesticides, Lewis Publishers.

   (5)  Verschueren, K. 1977, Handbook of Environmental Data on Organic Chemicals, Van Nostrand Reinhold.

   (6)  MacKay, D., et al. 1997, Illustrated Handbook of Physical-Chemical Properties and Environmental Fate for Organic Chemicals, 5 Volumes. Lewis Publishers, New York.

   (7)  Montgomery, J. H. 1991, Groundwater Chemicals Desk Reference, Vol. II. Lewis Publishers and Montgomery, J. H., and L. M. Welkom. 1990, Groundwater Chemicals Desk Reference Vol I, Louis Publishers.

   (8)  Milne, G.W.A., ed. 1995, CRC Handbook of Pesticides, CRC Press, Inc.

   (9)  National Library of Medicine (Grateful Med), Hazardous Substances Databank.

   (10)  EPA. 1994, Superfund Chemical Data Matrix. Office of Solid Waste and Emergency Response, EPA 540-R-94-009.

   (11)  Mabey, et al. 1982, Aquatic Fate Process Data for Organic Priority Pollutants, SRI. EPA Contract Nos. 68-01-3867, 68-03-2981.

   The provisions of this §  250.304 amended November 23, 2001, effective November 24, 2001, 31 Pa.B. 6395. Immediately preceding text appears at serial pages (233652) and (272687).

 (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 3 and 4. The methodology for calculating MSCs in soil is detailed in subsections (c)—(e) and the MSCs are 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 0.35, 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. This is calculated according to the equation in paragraph (1). For regulated substances which are organics and liquids at standard temperature and pressure (STP) as identified in Appendix A, Table 5 (Chemical Properties), the physical limitation is further limited based on residual saturation with the additional assumption of a residual saturation ratio of substance volume to soil volume of 0.051, as calculated in Equation (2).

 where:
 [rho ]_rs = density of the regulated substance = 1.0 kg/L
 n = porosity of the soil = 0.35
 [rho ]_B = dry bulk density of the soil = 1.8 kg/L
 Sr = residual saturation ratio (substance vol./soil vol.) = 0.051

 (c)  For the residential standard, the MSC for regulated substances contained in soil is one of the following:

   (1)  The lowest of the following:

     (i)   The ingestion numeric value throughout the soil column to a depth of up to 15 feet from the existing ground surface as determined by the methodology in §  250.306 (relating to ingestion numeric values), using the appropriate default residential exposure assumptions contained in §  250.306(e).

     (ii)   The inhalation numeric value throughout the soil column to 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 §  250.307 (relating to inhalation numeric values), using the appropriate default residential exposure assumptions contained in §  250.307(d).

     (iii)   The soil-to-groundwater pathway numeric value throughout the entire soil column as determined by the methodology in §  250.308 (relating to soil to groundwater pathway numeric values).

   (2)  The lowest of paragraph (1)(i) and (ii) and, in addition, one of the following:

     (i)   A demonstration of the soil-to-groundwater pathway soil buffer as identified in §  250.308(b), if applicable.

     (ii)   A soil-to-groundwater pathway equivalency demonstration as identified in §  250.308(d).

 (d)  For the nonresidential standard, the MSC for regulated substances contained in soil throughout the soil column to a depth of 2 feet from the existing ground surface is one of the following:

   (1)  The lowest of the following:

     (i)   The ingestion numeric value as determined by the methodology in §  250.306, using the appropriate default nonresidential exposure assumptions contained in §  250.306(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 §  250.307, using the appropriate default nonresidential exposure assumptions contained in §  250.307(d).

     (iii)   The soil-to-groundwater pathway numeric value throughout the entire soil column as determined by the methodology in §  250.308.

   (2)  The lowest of paragraph (1)(i) or (ii) and, in addition, one of the following:

     (i)   A demonstration of the soil-to-groundwater pathway soil buffer as identified in §  250.308(b), if applicable.

     (ii)   A soil-to-groundwater pathway equivalency demonstration as identified in §  250.308(d).

 (e)  For the nonresidential standard, the MSC for regulated substances contained in soils at depths greater than 2 feet through 15 feet from the existing ground surface, is one of the following:

   (1)  The lowest of the following:

     (i)   The inhalation numeric value which considers volatilization to the outdoor air, as determined by the methodology in §  250.307, using the appropriate default nonresidential exposure assumptions contained in §  250.307(d), and using a transfer factor (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 entire soil column as determined by the methodology in §  250.308.

   (2)  The value identified in paragraph (1)(i) and one of the following:

     (i)   A demonstration of the soil-to-groundwater pathway soil buffer as identified in §  250.308(b), if applicable.

     (ii)   A soil-to-groundwater pathway equivalency demonstration as identified in §  250.308(d).

 (f)  The MSC for regulated substances contained in soil at depths greater than 15 feet is one of the following:

     (i)   The soil-to-groundwater pathway numeric value as determined by §  250.308(a).

     (ii)   A demonstration of the soil-to-groundwater pathway soil buffer as identified in §  250.308(b), if applicable.

     (iii)   A soil-to-groundwater pathway equivalency demonstration as identified in §  250.308(d).

 (g)  A person conducting a remediation of soils contaminated with a substance having a secondary MCL will not be required to comply with the soil-to-groundwater pathway requirements for those substances to protect groundwater in aquifers for drinking water.

 (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 (d) 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 (d) 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 default exposure assumptions used to calculate the ingestion numeric values are as follows:

   Notes:
¹Residential exposure to noncarcinogens is based on childhood (ages 1-6) exposure for soil, and adult exposure for groundwater, consistent with USEPA (1991).
²Residential exposure to carcinogens is based on combined childhood and adult exposure.
³The 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.
⁴The Ingestion Factor for the residential scenario is calculated using the equation If_adj = ED_c x IR_c/BW_c + ED_a x IR_a/Bw_a, where ED_c = 6 yr, IR_c = 100 mg/day for soils and 1 L/day for groundwater, BW_c = 15 kg, ED_a = 24 yr, IR_a = 50 mg/day for soils and 2 L/day for groundwater, and BW_a = 70 kg. The ingestion factor for the nonresidential scenario is calculated using the equation If_adj = ED x IR/BW, where ED = 25 yr, IR = 50 mg/day for soils and 1 L/day for groundwater, and BW = 70 kg.
⁵In 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.

 (e) 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 7. 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 7 identifies each of the variables in this equation.

 (a)  For a regulated substance which is a systemic toxi- cant, 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:

   Notes: Modified from USEPA Region III Risk-based Concentration Table, dated October 20, 1995.
N/A = Not Applicable
¹Residential exposure to systemic toxicants is based on adult exposure, consistent with USEPA (1991).
²Residential exposure to carcinogens is based on combined child and adult exposure.
³Volatilization transport factor 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.
⁴Particulate transfer factor 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).
⁵In 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.
⁶Assumes 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.
⁷The inhalation factor for the residential scenario is calculated using the equation IF_adj = ED_c x IR_c/BW_c + ED_a x IR_a/Bw_a, where ED_c = 6 yr, IR_c = 0.5 m³/hr, BW_c = 15kg, ED_a = 24 yr, IR_a = 0.83 m³/hr, and BW_a = 70 kg. The inhalation factor for the nonresidential scenario is calculated using the equation IF_adj = 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 = (ER x DF)^-1

 The 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):

   ⁽¹⁾All default values from USEPA (1994) Draft Soil Screening Guidance, EPA-540/R-94/106, except as noted.
⁽²⁾Consistent with Standards Subcommittee recommendation.
⁽³⁾Based on Act 2 SAB-agreed depths.
⁽⁴⁾The Risk Assessment Subcommittee selected a f_oc of 0.005, which falls between f_oc’s of 0.006 for surface soil and 0.002 for subsurface soil.

 (f)  For a regulated substance which is a systemic toxicant and is a volatile compound, the numeric value for the inhalation of volatiles from groundwater was calculated by using the appropriate residential or nonresidential exposure assumptions from subsection (h) according to the following equation:

 (g)  For a regulated substance which is a carcinogen and is a volatile compound, the numeric value for the inhalation of volatiles from groundwater shall be calculated by using the appropriate residential or nonresidential exposure assumptions from subsection (h) according to the following equation:

 (h)  The default exposure assumptions used to calculate the inhalation numeric values for the inhalation of volatiles from groundwater are as follows:

   (Footnotes on next page)

   Notes: Modified from USEPA Region III Risk-based Concentration Table, dated October 20, 1995.
N/A = Not Applicable
¹Residential exposure to systemic toxicants is based on adult exposure, consistent with USEPA (1991).
²Residential exposure to carcinogens is based on combined child and adult exposure.
³In cases where the inhalation RfD or CSF is based on absorbed dose, this factor can be applied in the exposure algorithm.
⁴Default Transfer Factor is as presented in USEPA’s RAGS, Part B.
⁵The inhalation factor for the residential scenario is calculated using the equation IF_adj = ED_c x IR_c/BW_c + ED_a x IR_a/Bw_a, where ED_c = 6 yr, IR_c = 0.5 m³/hr, BW_c = 15 kg, ED_a = 24 yr, IR_a = 0.625 m³/hr, and BW_a = 70 kg. The inhalation factor for the nonresidential scenario is calculated using the equation IF_adj = ED x IR/BW, where ED = 25 yr, IR = 1.25 m³/hr and BW = 70 kg.

 (a)  A person may use the soil-to-groundwater pathway numeric values listed in Appendix A, Table 3B, as developed using the methods contained in paragraph (1), (2) or (4), 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, Tables 1 and 2, 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), or may use the soil-to-groundwater pathway soil buffer criteria in subsection (b) or may use the soil-to-groundwater pathway equivalency demonstration in subsection (d).

   (1)  A value which is 100 times the applicable MSC for groundwater identified in §  250.304(c) or (d) (relating to MSCs 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 soil not in the zone of groundwater saturation, the generic value shall be calculated by the equation in paragraph (3).

     (ii)   For soil in the zone of groundwater saturation, the standard is 1/10th of the generic value calculated by the equation in paragraph (3).

   (3)  The equation referenced in paragraphs (1) and (2) is the following:

 where: MSC_S (mg/kg) = the generic value for a regulated substance in soil

 MSC_GW (mg/L) = MSC of a regulated substance in groundwater

 K_oc (L/kg) = organic carbon partition coefficient for a regulated substance

 f_oc = fraction of organic carbon in soil (default value = 0.0025)

 [thgr ]_w = water-filled porosity of soil (default value = 0.2)

 [rho ]_b (kg/L) = dry bulk density of soil (default value = 1.8 kg/l)

 DF = dilution factor (default value = 100)

   (4)  For inorganic regulated substances, 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 (5) and listed in Appendix A, Table 4B.

     (i)   For soil not in the zone of groundwater saturation, the generic value shall be calculated by the equation in paragraph (5).

     (ii)   For soil in the zone of groundwater saturation, the standard is 1/10th of the generic value calculated by the equation in paragraph (5).

   (5)  The equation referenced in paragraph (4) is the following:

 where: MSC_S (mg/kg) = the generic value for the inorganic regulated substance in soil

 MSC_GW (mg/L) = MSC of the inorganic regulated substance in groundwater

 K_d (L/kg) = soil to water partition coefficient for the inorganic regulated substance

 [thgr ]_w = water-filled porosity of soil (default value = 0.2)

 [rho ]_b (kg/L) = dry bulk density of soil (default value = 1.8 kg/L)

 DF = dilution factor (default value = 100)

 (b)  The soil-to-groundwater pathway soil buffer is the entire area between the bottom of the area of contamination and the groundwater or bedrock and shall meet the following criteria:

   (1)  The soil depths established in Appendix A, Tables 3B and 4B for each regulated substance.

   (2)  The concentration of the regulated substance cannot exceed the limit related to the PQL or background throughout the soil buffer.

   (3)  No Karst carbonate formation underlies or is within 100 feet of the perimeter of the contaminated soil area.

 (c)  The soil-to-groundwater pathway soil buffer distances were developed by using the following equations.

   (1)  The following equations were used iteratively for each layer of soil for each time increment in a total time period of 30 years and pertain to a soil column where the first 4 feet of soil are contaminated with a regulated substance at a concentration of 10,000 mg/kg.

 where: C_soil(it) (mg/kg) = concentration of regulated substance in soil at layer i at time increment TI

 C_soil(i(t-1)) (mg/kg) = concentration of regulated substance in soil at layer i at time increment immediately preceding TI

 C_{soil(i+1)(t-1)} (mg/kg) = concentration of regulated substance in soil at layer immediately above layer i at time increment immediately preceding TI

 R (cm/yr) = recharge rate of water infiltrating soil (default value = 33 cm/yr)

 DI (feet) = thickness of each layer i of soil (default value = 1 foot)

 [rho ]_b (kg/L) = dry bulk density of soil (default value = 1.8 kg/L)

 360 (month-cm/yr-ft) = conversion factor

 TI (months) = time duration of each time increment

 [thgr ]_W = water-filled porosity (default value = 0.2)

 C_aq(i(t-1)) (mg/L) = concentration of regulated substance in soil pore water at layer i at time increment immediately preceding TI

 C_aq(i+1)(t-1) (mg/L) = concentration of regulated substance in soil pore water at layer immediately above layer i at time increment immediately preceding TI

 K_d (L/kg) = soil to water partition coefficient for the regulated substance where five different contaminant-specific values are used: 2.5, 5, 10, 100 and 1,000.

 K_d values of organic regulated substances are based on the following equation:

 K_d = (f_oc)(K_oc)

 where: f_oc = fraction of organic carbon in soil (default value = 0.005)

 K_oc (L/kg) = organic carbon partition coefficient for a regulated substance

   (2)  The buffer distances listed for regulated substances in Tables 3B and 4B were determined by the Department using these equations to model the distance that the regulated substance travels from the bottom of the first 4 feet of contaminated soil through the soil column in 30 years at a concentration at or above 1 µG/L in the water infiltrating the soil.

 (d)  For any regulated substance, an equivalency demonstration may be substituted for the soil-to-groundwater numeric value throughout the site and the soil-to-groundwater pathway soil buffer if the groundwater is below the MSC value or the background standard prior to remediation. This equivalency demonstration shall include the following:

   (1)  Fate and transport analysis of the regulated substance from the deepest point of contamination in the soil through unsaturated zone soil and shall include the use of soil-to-water partition coefficients. The analysis shall demonstrate that the regulated substances will not migrate to bedrock or the groundwater within 30 years at concentrations exceeding the greater of the groundwater MSC or background in groundwater as the endpoint in soil pore water directly under the site.

   (2)  In addition to sampling required for attainment of the inhalation or ingestion numeric values for soils up to 15 feet, as applicable, reporting and monitoring for eight quarters that shows no exceedances of the greater of the groundwater MSCs or of the background standard for groundwater beneath the contaminated soil and no indications of an increasing trend of concentration over time that may exceed the standard.

 (a)  Any regulated discharge to surface waters shall comply with the applicable provisions of Chapters 91—96, 97 (reserved), 102, 103 and 105, including antidegradation requirements, and may not cause an exceedance of the applicable water quality standards for the surface water in question.

 (b)  For point source discharges to surface water, compliance shall be measured at the point of discharge in accordance with limits specified in the NPDES permit.

 (c)  For purposes of determining compliance with surface water quality standards from a diffuse surface or groundwater discharge, the person shall determine the expected instream regulated substance concentrations, that are attributable to releases at the site, using mass balance techniques for groundwater/surface water mixing at design flow conditions.

   (1)  If the results indicate that surface water quality standards are being achieved, no action is required.

   (2)  If results indicate that surface water quality standards are not being achieved, additional sampling may be performed to help evaluate whether surface water quality standards are being achieved.

   (3)  If the results of the sampling indicate surface water quality standards are being met, no further action is required.

   (4)  If the results of the modeling, and sampling if any, indicate that surface water quality standards are not being met, the person shall perform further remedial action to attain the surface water quality standards.

 (d)  Except if an NPDES permit is required, for purposes of complying with surface water quality standards in a spring, the point of compliance is the point of first designated or existing use, as defined in § §  93.1, 93.4 and 93.9 (relating to definitions; Statewide water uses; and designated water uses and water quality criteria). If the point of first designated or existing use occurs in a surface water into which a spring flows, compliance with surface water quality standards shall be determined in the manner specified in subsection (c).

 (a)  For regulated substances listed in Appendix A, Table 6 that are found in groundwater, the minimum threshold MSC of 5 micrograms per liter in groundwater, shall be used.

 (b)  For regulated substances listed in Appendix A, Table 6 that are found in soil, the lowest of one of the following values shall be used as the minimum threshold MSC:

   (1)  An ingestion numeric value of 100 milligrams per kilogram in soil.

   (2)  The soil-to-groundwater pathway numeric value throughout the soil column as determined by the methodology in §  250.308 (relating to soil-to-groundwater pathway numeric values), but substituting 5 micrograms per liter in groundwater for the groundwater MSC. The soil-to-groundwater pathway numeric value shall be calculated by using a concentration in soil at the site which does not produce a leachate in excess of the MSC for groundwater or by using a value which is 100 times the MSC for groundwater, expressed in milligrams per kilogram of soil. An equivalency demonstration under §  250.308(d) may be substituted for the soil-to-groundwater numeric value.

 (c)  The minimum threshold MSC in subsection (a) and the ingestion numeric value in subsection (b)(1) are calculated according to the following exposure assumption and equation: 0.50 ppb dietary intake corresponds to a 1x10^-6 risk (USFDA Threshold of Regulation Final Rule July 17, 1995) assuming the substance is a carcinogen. Correcting this value (or 5.0 ppb) to the 10^-5 risk level, in Statewide health standard formulation, the threshold of regulation concentrations are determined by the following exposure assumptions and calculations:

 Five µg/kg (substance of concern) threshold level corresponding to 1x10^-5 risk

 Dietary intake 2 kg/day x 5 µg/kg (substance - 10 µg/day (daily intake of substance of concern)

 For soil ingestion: 10 µg/100 mg soil or 100 mg/kg = Threshold concentration for soils

 For groundwater ingestion: 10 µg/2L water = 5 µg/L - Threshold concentration for water

 (a)  In addition to any protection afforded under other requirements for meeting surface water and air quality standards and MSCs under this chapter, based on the screening process in this section, direct impacts from regulated substances to the following receptors shall be assessed and addressed to implement a remedy that is protective of the environment:

   (1)  Individuals of threatened or endangered species as designated by the United States Fish and Wildlife Service under the Endangered Species Act (16 U.S.C.A. § §  1531—1544).

   (2)  Exceptional value wetlands as defined in §  105.17 (relating to wetlands).

   (3)  Habitats of concern.

   (4)  Species of concern.

 (b)  For purposes of determining impacts on ecological receptors, no additional evaluation is required if the remediation attains a level equal to 1/10th of the value in Appendix A, Tables 3 and 4, except for constituents of potential ecological concern identified in Table 8, or if the criteria in paragraph (1), (2) or (3) are met. Information that supports a determination that no additional evaluation is required shall be documented in the final report.

   (1)  Jet fuel, gasoline, kerosene, number two fuel oil or diesel fuel are the only constituents detected onsite.

   (2)  The area of contaminated soil is less than 2 acres and the area of contaminated sediment is less than 1,000 square feet.

   (3)  The site has features, such as buildings, parking lots or graveled paved areas, which would obviously eliminate the specific exposure pathways, such as soils exposure.

 (c)  If none of the criteria in subsection (b) are met and if no Constituents of Potential Ecological Concern (CPECs) associated with the release being addressed as part of an NIR at the site, as identified in Appendix A, Table 8, are detected onsite, an onsite evaluation shall be conducted to document any indications of ecological impact. Ecological impacts requiring more detailed evaluation exist if there are differences of greater than 50% in the density or diversity of species or habitats of concern when compared with nearby reference areas representing equivalent ecological areas without contamination, if available. This evaluation shall also document the presence of threatened and endangered species and exceptional value wetlands. If no ecological impacts requiring further evaluation are identified, and no threatened and endangered species exist within a 2,500-foot radius of the site and no exceptional value wetlands exist on the site, no further evaluation is required and that determination shall be documented in the final report.

 (d)  If none of the criteria in subsection (b) are met and if CPECs associated with the release being addressed as part of an NIR at the site are detected onsite or ecological impacts requiring more detailed evaluation, threatened and endangered species, or exceptional value wetlands as identified in subsection (c) exist, a detailed onsite evaluation shall be conducted by a person qualified to perform environmental risk assessments to document any substantial ecological impacts. Substantial ecological impacts exist if there are differences of greater than 20% in the density of species of concern or greater than 50% in the diversity and extent of habitats of concern when compared with nearby reference areas representing equivalent ecological areas without contamination, if available. If there are no substantial ecological impacts identified and there are no threatened or endangered species on or within a 2,500-foot radius of the site and no exceptional value wetlands on the site, that determination shall be provided in the final report.

 (e)  If the person cannot demonstrate that they meet the criteria in subsection (b), and cannot demonstrate that the evaluation performed under subsection (c) identified no ecological impacts requiring more detailed evaluation under subsection (d), or cannot demonstrate that the evaluation performed under subsection (d) identified no substantial ecological impacts, or threatened or endangered species or exceptional value wetlands, one of the following shall be met:

   (1)  A person shall demonstrate in the final report that attainment of the Statewide health standard MSCs are protective of the ecological receptors.

   (2)  If a demonstration cannot be made that the Statewide health standard MSCs are protective of ecological receptors, a person shall demonstrate in the final report that postremedy use will eliminate complete exposure pathways at the time of the final report or in accordance with a postremediation care plan, or that mitigative measures identified in subsection (f) have been instituted and are subject to postremediation care plan requirements as described in §  250.312(b) (relating to final report).

   (3)  A person shall demonstrate attainment of the background standard.

   (4)  A person shall follow the procedures in § §  250.402(c) and 250.409 (relating to human health and environmental protection goals; and risk assessment report) and demonstrate attainment of the site-specific standard for protection of ecological receptors.

 (f)  Mitigation measures to restore or replace equivalent ecological resources in the local area of the site may be applied if the following are met:

   (1)  No exceptional value wetlands have been identified by the screening process.

   (2)  No Federal or State laws and regulations prohibit or restrict the elimination of habitats or species identified by the screening process.

   (3)  A mitigation measure is selected based on the following hierarchy:

     (i)   Restoration onsite of species and habitats identified in the screening process.

     (ii)   Replacement onsite of species and habitats identified in the screening process.

     (iii)   Replacement on an adjacent area to the site of species and habitats identified in the screening process.

     (iv)   Replacement at a location within the municipality where the site is located of species and habitats identified in the screening process.

   (4)  The Department will review and approve mitigation measures prior to implementation to ensure that the proposed remedy and intended use of the property minimize the impacts to ecological receptors identified in the screening procedure.

   (5)  The postremediation care plan requirements in §  250.312(e) or §  250.411(f) (relating to final report) are implemented.

   The provisions of this §  250.311 amended November 23, 2001, effective November 24, 2001, 31 Pa.B. 6395. Immediately preceding text appears at serial pages (233673) to (233675).

 (a)  For sites remediated under the Statewide health standard, the person conducting the remediation shall submit a final report to the Department which documents attainment of the selected standard. This final report shall include site characterization information identified in §  250.204(b)—(e) (relating to final report). The site characterization shall be conducted in accordance with scientifically recognized principles, standards and procedures. The level of detail in the investigation, and the selected methods and analyses, that may include models, shall sufficiently define the rate of movement and the present and future extent and fate of contaminants to ensure continued attainment of the remediation standard. Interpretations of geologic and hydrogeologic data shall be prepared by a professional geologist licensed in this Commonwealth.

 (b)  The final report for the Statewide health standard shall include the results of the evaluation of ecological receptors. If a person relies on a postremedy use to eliminate complete exposure pathways that is not implemented at the time of the final report submission, a postremediation care plan shall be submitted to document that the postremedy use is implemented within 1 year from final report approval, unless the Department approves an extension of time. If mitigation measures are implemented under §  250.311 (relating to evaluation of ecological receptors), a postremediation care plan shall be documented in the final report that includes the following:

   (1)  A plan to maintain the mitigated ecological resource.

   (2)  Reporting of the ongoing success or failure of the mitigation measure implemented.

   (3)  Mitigation measures, instituted at the time of the final report, shall be successfully accomplished and sustained up to 5 years from final report approval.

 (c)  Final reports for the Statewide health standard shall include information on the basis for selecting residential or nonresidential standards and the additional information identified in §  250.204(f)(1)—(5).

 (d)  The final report for the Statewide health standard shall include all sampling data and 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).

 (e)  If engineering controls are needed to attain or maintain a standard, if institutional controls are needed to maintain a standard, if the fate and transport analysis indicates that the remediation standard, including the solubility limitation in §  250.304(b) (relating to MSCs for groundwater), may be exceeded at the point of compliance in the future, or if the remediation relies on natural attenuation, a postremediation care plan shall be documented in the final report that includes the information identified in §  250.204(g).

 (f)  If the soil to groundwater pathway soil buffer distances are used, as identified in §  250.308 (relating to soil-to-groundwater pathway numeric values), the following information shall be included in the final report:

   (1)  Information demonstrating that the actual site soil column thickness below the contaminated soil by the information gathered from soil sample borings conducted during the site characterization is at least the thickness identified in Appendix A, Tables 3 and 4.

   (2)  Information gathered during the field investigation phase and the laboratory analyses conducted on the soil samples.

   (3)  The boring logs and all other data presented in appropriate maps, cross sections, figures and tables.

 (g)  If an equivalency demonstration is used under §  250.308(d), the following information shall be included in the final report:

   (1)  Information describing the actual site soil column below the contaminated soil determined by soil sample borings conducted during the site characterization.

   (2)  Information gathered during the field investigation phase and the laboratory analyses conducted on the groundwater samples beneath the contaminated soil.

   (3)  The boring logs and all other data presented in appropriate maps, cross sections, figures and tables.

   (4)  Sampling data, in a tabular format, that shows no exceedances of groundwater MSCs or the background standard, under §  250.308(d)(2).

   (5)  A demonstration, submitted in a graphic format, that sampling data indicates no increasing trend of concentration over time that may exceed the standard.

 (h)  When a person implements a remedy that relies on access to properties owned by third parties, for remediation or monitoring, documentation of cooperation or agreement shall be submitted as part of the final report.

   This section cited in 25 Pa. Code §  245.313 (relating to remedial action completion report); and 25 Pa. Code §  250.311 (relating to evaluation of ecological receptors).