[27 Pa.B. 4181]
[Continued from previous Web Page] § 250.308. Soil to groundwater pathway numeric values.
(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:
MSCS = MSCGW ((Koc * foc) + |gvw/|grb) DF
where: MSCS (mg/kg) = the generic value for a regulated substance in soil
MSCGW (mg/L) = MSC of a regulated substance in groundwater
Koc (L/kg) = organic carbon partition coefficient for a regulated substance
foc = fraction of organic carbon in soil (default value = 0.0025)
|gvw = water-filled porosity of soil (default value = 0.2)
|grb (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:
MSCS = MSCGW (Kd + |gvw/|grb) DF
where: MSCS (mg/kg) = the generic value for the inorganic regulated substance in soil
MSCGW (mg/L) = MSC of the inorganic regulated substance in groundwater
Kd (L/kg) = soil to water partition coefficient for the inorganic regulated substance
|gvw = water-filled porosity of soil (default value = 0.2)
|grb (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: Csoil(it) (mg/kg) = concentration of regulated substance in soil at layer i at time increment TI
Csoil(i(t-1)) (mg/kg) = concentration of regulated substance in soil at layer i at time increment immediately preceding TI
Csoil(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)
|grb (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
|gvW = water-filled porosity (default value = 0.2)
Caq(i(t-1)) (mg/L) = concentration of regulated substance in soil pore water at layer i at time increment immediately preceding TI
Caq(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
Kd (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.
Kd values of organic regulated substances are based on the following equation:
Kd = (foc)(Koc)
where: foc = fraction of organic carbon in soil (default value = 0.005)
Koc (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.
§ 250.309. MSCs for surface water.
(a) Any regulated discharge to surface waters shall comply with the applicable provisions of Chapters 91--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).
§ 250.310. Minimum threshold MSCs.
(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 1×10-6 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 1×10-5 risk
Dietary intake 2 kg/day × 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
The 100 mg soil and 2L water factors are the default ingestion rates from § 250.306(c) (relating to ingestion numeric values).
§ 250.311. Evaluation of ecological receptors.
(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 United StatesC.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 paragraphs (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), 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 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.
§ 250.312. Final report.
(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), 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.
Subchapter D. SITE-SPECIFIC STANDARD Sec.
250.401. Scope. 250.402. Human health and environmental protection goals. 250.403. Use of groundwater. 250.404. Pathway identification and elimination. 250.405. When to perform a risk assessment. 250.406. Relationship to surface water quality requirements. 250.407. Point of compliance. 250.408. Remedial investigation report. 250.409. Risk assessment report. 250.410. Cleanup plan. 250.411. Final report. § 250.401. Scope.
(a) This subchapter sets forth requirements and procedures for any person selecting the site-specific standards.
(b) The Department may approve or disapprove a remedial investigation report, a risk assessment report or cleanup plan based on consideration of all subsections in section 304 of the act (35 P. S. § 6026.304).
§ 250.402. Human health and environmental protection goals.
(a) Site-specific standards shall be developed that meet the human health and environmental protection goals specified in this section. The development of site-specific standards shall be based on a site-specific risk assessment, if required.
(b) The site-specific standard shall be a protective level that eliminates or reduces any risk to human health in accordance with the following:
(1) For known or suspected carcinogens, soil and groundwater cleanup standards shall be established at exposures which represent an excess upperbound lifetime risk of between 1 in 10,000 and 1 in 1 million. The cumulative excess risk to exposed populations, including sensitive subgroups, may not be greater than 1 in 10,000.
(2) For systemic toxicants, soil and groundwater cleanup standards shall represent the level to which the human population could be exposed on a daily basis without appreciable risk of deleterious effect to the exposed population. Where several systemic toxicants affect the same target organ or act by the same method of toxicity, the hazard index may not exceed one.
(c) In addition to any protection afforded under other requirements for meeting surface water and air quality standards under this chapter, direct impacts resulting from a release of regulated substances to the receptors identified in § 250.311(a) (relating to evaluation of ecological receptors) shall be assessed and addressed in the remedial investigation, risk assessment and cleanup plans.
(d) If a person is using the site-specific standard to protect ecological receptors under this subchapter or in accordance with § 250.311(e), the following shall be performed:
(1) An ecological risk assessment to determine if an impact has occurred or will occur if the release of a regulated substance goes unabated.
(2) An ecological risk assessment conducted in accordance with Department-approved EPA or ASTM guidance to establish acceptable remediation levels or alternative remedies based on current and future use that are protective of the ecological receptors.
(3) Implementation of the selected remedy, which may include mitigation measures under § 230.311(f), that is protective of the ecological receptors.
[Continued on next Web Page]
No part of the information on this site may be reproduced for profit or sold for profit.This material has been drawn directly from the official Pennsylvania Bulletin full text database. Due to the limitations of HTML or differences in display capabilities of different browsers, this version may differ slightly from the official printed version.
