[26 Pa.B. 3985]
[Continued from previous Web Page] 
§ 250.309. Minimum threshold MSCs.
(a) For regulated substances listed in Appendix A, Table 4 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 4 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 § 250.307 (relating to soil to groundwater pathway numeric values), but substituting 5 micrograms per liter in groundwater for the groundwater MSC.
(c) The person shall assess and address substantial direct impacts to ecological receptors and any impact to an individual species of concern in § 250.310(a)(2) (evaluation of ecological receptors), rare, threatened and endangered species, and exceptional value wetlands from regulated substances in Appendix A, Table 4 in accordance with § 250.310 (relating to evaluation of ecological receptors).
(d) 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
5 ug/kg (substance of concern) threshold level corresponding to 1×10-5 risk
dietary intake 2 kg/day × 5 ug/kg (substance - 10 ug/day (daily intake of substance of concern)
For soil ingestion: 10 ug/100 mg soil or 100 mg/kg = Threshold concentration for soils
For groundwater ingestion: 10 ug/2L water = 5 ug/L - Threshold concentration for water
The 100 mg soil and 2L water factors are the default ingestion rates from § 250.305(c) (relating to ingestion numeric values).
§ 250.310. Evaluation of ecological receptors.
(a) In addition to any protection afforded under other requirements for meeting surface water and air quality standards under this chapter, direct impacts, based on the screening process set forth in this section, 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 rare, threatened or endangered species.
(2) Individuals of species of special concern as identified by the Game Commission and the Fish and Boat Commission.
(3) Exceptional value wetlands.
(4) Habitats of concern.
(5) Species of concern.
(b) Procedures for determining any impact on the receptors identified in subsection (a) shall be as follows:
(1) Determine if jet fuel, gasoline, kerosene, number two fuel oil or diesel fuel, are the only constituents detected onsite and that no nonaqueous phase liquids are present. Under these conditions, the site will not require further evaluation of ecological receptors and the information that supports this determination shall be documented in the final report.
(2) Determine if one of the following exists:
(i) The area of the impacted surface soil at the site is equal to or greater than 2 acres.
(ii) The impacted sediment is equal to or greater than 1,000 square feet.
If the area meets either of these size limitations, then the site will require further evaluation of ecological receptors and the information that supports this determination shall be documented in the final report.
(3) Determine whether any of the constituents detected at the site are considered to be constituents of potential ecological concern (CPECs), as identified in Appendix A, Table 7.
(i) If no CPECs are detected at the site, then further ecological evaluation is required in accordance with paragraph (4).
(ii) If CPECs have been detected at the site, then further ecological evaluation is required in accordance with paragraph (5).
(4) Determine, based on the evaluation of an environmental scientist who is qualified to perform environmental assessments, whether indications of substantial ecological impacts or any individual species of special concern, rare, threatened or endangered species exist by performing a preliminary site walk evaluation.
(i) The preliminary site walk evaluation requires the following conditions to be met:
(A) Review of readily available site background information.
(B) A preliminary walk of the area of concern to identify evidence of ecological impacts, such as signs of stressed or dead vegetation, discolored soil, sediment or water, the presence of deformed organisms and the presence of nonnative materials in sediments resulting from seeps or other discharges from the site, and to identify nearby reference areas representing equivalent ecological areas without contamination, if available, that are outside the area of contamination on the site.
(C) Preparation of a summary of findings that documents whether differences of greater than 50% in the density of species of concern or in the diversity and extent of habitats of concern exist. If differences of greater than 50% exist, then indications of substantial ecological impacts exist. The summary of findings shall document the existence of any individual species of special concern in subsection (a)(2), rare, threatened or endangered species and any exceptional value wetlands.
(ii) If indications of substantial ecological impacts exist, or if any individual species of special concern in subsection (a)(2) exist, rare, threatened or endangered species exist, or any exceptional value wetlands exist, further evaluation of ecological receptors is required in accordance with paragraph (5).
(iii) If no indications of substantial ecological impacts exist under subparagraph (i)(C) and no other ecological receptors exist under subparagraph (i)(C), the site will not require further evaluation of ecological receptors and the information that supports this determination shall be documented in the final report.
(5) Determine whether the site has features, such as buildings, parking lots or graveled paved areas, which would obviously eliminate specific pathways, such as soils exposure.
(i) As long as all pathways are eliminated by the feature, the site will not require further evaluation of ecological receptors and the information that supports this determination shall be documented in the final report.
(ii) If pathways are not eliminated, then further ecological evaluation is required in accordance with paragraph (6).
(6) Determine, based on the evaluation of an environmental scientist who is qualified to perform detailed environmental risk assessments, whether species of concern or habitats of concern or exceptional value wetlands exist on the site or, for individual species of special concern in subsection (a)(2), or for individual rare, endangered and threatened species if those species exist on the site or within a 2,500-foot radius of the border of the site in its current and intended use by conducting a formal site walk evaluation.
(i) The formal site walk evaluation shall include the following:
(A) Review of readily available site background information.
(B) Identification of physical and habitat features of the area and nearby reference areas which are outside the area of contamination on the site.
(C) Qualitative evaluation of whether species of concern or habitats of concern are present at the site and in the reference area.
(D) Identification of evidence of ecological impacts as compared with the reference area. The identification shall include the following impacts: signs of stressed or dead vegetation, discolored soil, sediment or water; the presence of deformed organisms and the presence of nonnative materials in sediments resulting from seeps or other discharges from the site; community composition differences; the absence of biota compared with similar areas of the system; the presence of nonnative or exotic species; the presence of individual species of special concern in subsection (a)(2), rare, threatened or endangered species; the existence of exceptional value wetlands; and the potential for residual contamination to habitats of concern and areas utilized by species of concern.
(E) Identification of the existence of exposure pathways.
(F) Preparation of a summary of findings that documents whether 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 exist. If differences of greater than the 20% or 50% exist, then substantial ecological impacts exist. The summary of findings shall document the existence of any individual species of special concern in subsection (a)(2), rare, threatened or endangered species and exceptional value wetlands.
(ii) If no species of concern or habitats of concern or exceptional value wetlands exist on the site and no species of special concern in subsection (a)(2), no rare, threatened or endangered species exist within a 2,500-foot radius of the border of the site, the site will not require further evaluation of ecological receptors and the information that supports this determination shall be documented in the final report.
(iii) If substantial ecological impacts exist, as identified in subparagraph (i)(F), or if any individual species of special concern in subsection (a)(2), rare, threatened or endangered species exist, further ecological evaluation is required in accordance with paragraph (7). If exceptional value wetlands exist, the requirements of paragraph (7)(i) shall be met.
(7) Determine whether a complete exposure pathway to species of concern or habitats of concern substantially impacted exists or whether a complete exposure pathway to species of special concern in subsection (a)(2), rare, threatened or endangered species exist at the site in its current and intended use.
(i) If a complete exposure pathway, a regulated substance and either a substantial impact or any individual species of special concern in subsection (a)(2), rare, threatened or endangered species exist, one of the following shall be met:
(A) The person shall demonstrate in the final report that attainment of the Statewide health standard is protective of the ecological receptor.
(B) The person shall demonstrate attainment of the background standard.
(C) The person shall follow the procedures in § 250.402(d) (relating to human health and environmental protection goals) and demonstrate attainment of the site-specific standard.
(ii) If no complete exposure pathway exists, then the results of the screening procedure shall be reported in the final report for the statewide health standard or the risk assessment report for the site-specific standard. The final report shall include the basis for the conclusion that a substantial ecological impact is unlikely and that further ecological evaluation is not required.
§ 250.311. 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 methods selected shall sufficiently define the rate, extent and movement of contaminants. 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.
(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)--(4).
(d) 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 that includes the information identified in § 250.204(g).
Subchapter D. SITE-SPECIFIC STANDARD Sec.
250.401. Scope. 250.402. Human health and environmental protection goals. 250.403. Use of groundwater in an aquifer. 250.404. Pathway identification and elimination. 250.405. When to perform a risk assessment. 250.406. Point of compliance. 250.407. Remedial investigation report. 250.408. Risk assessment report. 250.409. Cleanup plan. 250.410. 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 § 250.310(a) (relating to evaluation of ecological receptors) shall be assessed and addressed in the remedial investigation, risk assessment and cleanup plans in accordance with § 250.310(b).
(d) If the ecological screening procedure in § 250.310 indicates a complete exposure pathway, a regulated substance and either a substantial impact or any individual species of special concern in § 250.310(a)(2), rare, threatened or endangered species, then 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 the most recent EPA or ASTM guidance identified in subsection (e) 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 that is protective of the ecological receptors.
(e) The references identified in subsection (d)(2) are as follows:
(1) EPA/540/1-89/001 ''Risk Assessment Guidance for Superfund, Volume 2: Environmental Evaluation Manual,'' March, 1989.
(2) EPA/600/3-89/013 ''Ecological Assessment of Hazardous Waste Sites: A Field and Laboratory Reference Document.'' PB89205967. March, 1989.
(3) EPA/600/R-93/187A ''Wildlife Exposure Factors Handbook.'' PB94-174778.
(4) ASTM ES38. ''Emergency Standard Guide for Risk-Based Corrective Action Applied at Petroleum Release Sites.''
§ 250.403. Use of groundwater in an aquifer.
(a) Groundwater will not be considered a current or potential source of drinking water where groundwater has a background of total dissolved solids greater than 2,500 milligrams per liter.
(b) Except as provided subsection (a), current use and future use of aquifer groundwater shall be determined in accordance with § 250.6 (relating to current use and future use of aquifer groundwater).
(c) Drinking water use of groundwater in an aquifer shall be made suitable by at least meeting the primary and secondary MCLs at all points of exposure identified in § 250.404 (relating to pathway identification and elimination).
§ 250.404. Pathway identification and elimination.
(a) The person shall consult the most recent EPA or ASTM guidance, referenced in subsection (d), to identify any potential current and future exposure pathways for both human receptors and environmental receptors identified in § 250.402 (relating to human health and environmental protection goals).
(b) The person shall summarize pathways for current land use and any probable future land use separately in the site-specific remedial investigation report. If no exposure pathway exists, the remedial investigation report shall contain information necessary to determine that no current or future exposure pathway exists.
(c) Prior to performing a risk assessment as required in § 250.405 (relating to when to perform a risk assessment), the person may take into account the effect of engineering and institutional controls in eliminating pathways identified in subsection (b) and include this evaluation in the remedial investigation report.
(d) The references identified in subsection (a) are as follows:
(1) ASTM E 1689, Standard Guide for Developing Conceptual Site Models for Contaminated Sites.
(2) ASTM E 978, Standard Practice for Evaluating Mathematical Models for the Environmental Fate of Chemicals.
(3) For petroleum release sites, risk assessment methodology in ASTM ES 38 (Emergency Standard Guide for Risk-Based Corrective Action Applied at Petroleum Release Sites) may be consulted for guidance.
(4) Interim Final Risk Assessment Guidance for Superfund, Volume I, Human Health Evaluation Manual, Part A, Baseline Risk Assessment (RAGS Volume 1 Part A). EPA/540/1-89/002.
(5) Interim Final Human Health Evaluation Manual, Supplemental Guidance, ''Standard Default Exposure Factors,'' OSWER Directive 9285.6-03.
(6) Interim Final Guidance for Soil Ingestion Rates. OSWER Directive 9850.4.
(7) Exposure Factors Handbook. EPA/600/8-89/043.
(8) Interim Final Guidance for Data Usability in Risk Assessment. EPA/540/G-90/008.
(9) Superfund Exposure Assessment Manual. EPA/540/1-88/001, OSWER Directive 9285.5-1.
(10) U. S. EPA Region III Technical Guidance Manual, Risk Assessment, Chemical Concentration Data Near the Detection Limit. EPA/903/8-91/001.
(11) U. S. EPA Region III Technical Guidance Manual, Risk Assessment, Exposure Point Concentrations in Groundwater. EPA/903/8-91/002.
(12) U. S. EPA Region III Technical Guidance Manual, Use of Monte Carlo Simulation in Risk Assessments. EPA 903-F-94001.
(13) U. S. EPA Region III Technical Guidance Manual, Risk Assessment, Selecting Exposure Routes and Contaminants of Concern by Risk-Based Screening. EPA/903/R-93-001.
§ 250.405. When to perform a risk assessment.
(a) Except as specified in subsections (b) and (c), a person who remediates under this subchapter shall develop site-specific standards based on a risk assessment. The person shall conduct the risk assessment according to the procedures specified in Subchapter F (relating to exposure and risk determinations).
(b) The risk assessment report is not required if a fate and transport analysis which takes into account the effects of engineering and institutional controls demonstrates that neither present nor future exposure pathways exist. This demonstration shall follow the procedures described in § 250.404 (relating to pathway identification and elimination).
(c) The baseline risk assessment report is not required if the Department, in its remedial investigation report or cleanup plan approval, determines that a specific remediation measure that eliminates all pathways, other than a no-action remedial alternative, can be implemented to attain the site-specific standard in accordance with the requirements of attainment demonstration as specified in Subchapter G (relating to demonstration of attainment). A baseline risk assessment is that portion of a risk assessment that evaluates a risk in the absence of the proposed site-specific measure.
§ 250.406. Point of compliance.
(a) 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.
(b) 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 diffuse discharges shall meet the applicable regulations and shall achieve water quality that does not preclude uses existing prior to the contamination from this source.
(c) 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.
(d) For attainment of a site-specific standard in groundwater for ingestion and inhalation exposures, the point of compliance is at and beyond the property boundary in the intervals specified in subsection (d) at the time the contamination is discovered or a point beyond the property boundary that the Department may determine to be otherwise 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. A secondary contaminant is a substance for which a secondary MCL exists.
(e) For attainment of a site-specific standard for volatilization directly to indoor air, the point of compliance is the point of exposure where there is exposure on the site in a below-grade occupied space.
(f) For attainment of site-specific soil standards in residential areas, the point of compliance for ingestion and inhalation exposure is up to 15 feet below the existing surface unless bedrock or physical structures are encountered which prevent safe continued remediation.
(g) For attainment of site-specific soil standards in nonresidential areas, the point of compliance for ingestion, inhalation and volatilization is the point of exposure as identified in an approved risk assessment report, if required.
(h) For attainment of soil to groundwater soil standards in both residential and nonresidential areas, the point of compliance is throughout the soil column.
(i) For the emission of regulated substances to outdoor air, the point of compliance for the air quality standard shall be as specified in the air quality regulations.
§ 250.407. Remedial investigation report.
(a) Persons electing to remediate a site to the site-specific standard shall submit a remedial investigation report to the Department for review and approval. This report shall include documentation and a description of the procedures and conclusions from the site characterization conducted according to the requirements of subsections (b)--(e). The site characterization shall be conducted in accordance with scientifically recognized principles, standards and procedures. The level of detail in investigation and the methods selected shall sufficiently define the rate, extent and movement of contaminants. Interpretations of geologic and hydrogeologic data shall be prepared by a professional geologist licensed in this Commonwealth.
(b) As directed from specific knowledge of the subject property, historic use of the subject property or regulated substance usage information regarding the subject property, an appropriate number of sample locations should be investigated from the identified media of concern to characterize the nature and composition of the contaminants including: source characterization or development of a conceptual site model, the vertical and horizontal extent of contamination above the selected standard within each media of concern, the direction and rate of contaminant movement within each media of concern and determination of the appropriate remedial technology for each media of concern.
(c) Descriptions of sampling and decontamination methodologies and analytical quality assurance/quality control procedures should be included within a sampling and analysis plan and quality assurance plan. Copies of soil and geologic boring descriptions and as-built construction drawings of wells used for site characterization should be included in the report. Copies of all laboratory analytical results and applicable laboratory quality control results should be included within the report, including all historical data and data eliminated from consideration based on data validation protocols. Analytical results should be presented within the report in table form.
(d) If soil is determined to be a media of concern, the site characterization shall determine the relative location of the soil samples necessary to characterize the horizontal and vertical extent of contamination, and factors which could relate to the movement of the contamination. 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, in order to determine the applicability of the proposed remedial action and handling and disposal requirements 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. When 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 influence from pumping wells. 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. 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. 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) The comments obtained as a result of a public involvement plan, if any, and the responses to those public comments shall be included in a remedial investigation report.
§ 250.408. Risk assessment report.
The risk assessment report shall conform to this subchapter and Subchapter F (relating to exposure and risk determinations), and shall include the following unless not required under § 250.405 (relating to when to perform a risk assessment):
(1) A risk assessment report that describes the potential adverse effects, including the evaluation of ecological receptors, under both current and planned future conditions caused by the presence of regulated substances in the absence of any further control, remediation or mitigation measures.
(2) The development of the site-specific standards risk assessment report that describes the methods used to calculate a concentration level at which human health and the environment are protected.
(3) The comments obtained as a result of a public involvement plan, if any, and the responses to those public comments.
§ 250.409. Cleanup plan.
(a) A cleanup plan is required to be submitted to the Department for approval when the site-specific standard is selected as the remediation goal. The cleanup plan shall evaluate the relative abilities of the alternative remedies to achieve the site-specific standard and propose a remedial measure which shall achieve the standard established according to the procedures contained in this subchapter. The person submitting the plan shall evaluate additional alternative remedies that have been requested for evaluation by the Department in accordance with the act.
(b) The cleanup plan shall include remedial alternatives and a proposed remedy that document how each of the potential remedies relate to the factors identified in section 304(j) of the act (35 P. S. § 6026.304(j)).
(c) Other components of the cleanup plan include:
(1) Site maps.
(2) The results of treatability, bench scale or pilot scale studies or other data collected to support the remedial actions.
(3) A final design which consists of complete plans and specifications.
(4) The comments obtained as a result of a public involvement plan and the responses to those public comments.
(5) Documentation of proposed postremediation care requirements if they are needed to maintain the standard.
[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.
