[27 Pa.B. 4181]
[Continued from previous Web Page] § 250.403. Use of groundwater.
(a) Groundwater will not be considered a current or potential source of drinking water where groundwater has a background total dissolved solids concentration greater than 2,500 milligrams per liter.
(b) Except as provided in subsection (a), current and probable future use of groundwater shall be determined on a site-specific basis.
(c) Drinking water use of groundwater 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).
(d) Current drinking water or agricultural uses of groundwater, at the time contamination was discovered, shall be protected.
§ 250.404. Pathway identification and elimination.
(a) The person shall use Department-approved EPA or ASTM guidance 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.
(c) If no exposure pathway exists, and no remedy is required to be proposed and completed, the following apply:
(1) The remedial investigation report shall contain information necessary to determine that no current or future exposure pathway exists.
(2) A risk assessment, including an ecological risk assessment, and cleanup plan are not required.
(3) The remedial investigation report and the final report may be submitted simultaneously.
(d) 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.
§ 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. Relationship to surface water quality requirements.
(a) A regulated discharge to surface waters shall comply with the applicable provisions of Chapters 91--105, including antidegradation requirements.
(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 and appropriate sampling 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, additional sampling may be performed to help evaluate whether surface water quality standards are being achieved. If the results of the sampling indicate the surface water quality standards are being met, no further action is required. If the results of the modeling, and sampling if any, indicate the surface water quality standards are not being met, the person shall perform further remedial action to attain the surface water quality standards, unless a waiver of the surface water quality standards is obtained under paragraphs (1) and (2).
(1) In the case of a diffuse surface or groundwater discharge which existed at the time contamination was discovered, the Department may waive any otherwise applicable provisions, including the provisions of Chapter 93 (relating to water quality standards), under section 902(b) of the act (35 P. S. § 6026.902(b)).
(2) An applicant for a waiver of provisions in Chapter 93 shall demonstrate to the Department that the proposed remedial alternative will result in attainment of a concentration in the stream that does not exceed human health criteria and aquatic life criteria under the requirements in Chapter 93. The person may propose the use of alternative site-specific exposure factors or design conditions that will demonstrate attainment of the human health criteria.
(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). Where 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).
§ 250.407. Point of compliance.
(a) For attainment of a site-specific standard in groundwater, the point of compliance is the property boundary that existed at the time the contamination was discovered. Site-specific 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 secondary contaminants.
(b) For attainment of a site-specific standard in residential areas 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.
(c) 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.
(d) 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.
(e) For attainment of soil-to-groundwater soil standards in both residential and nonresidential areas, the point of compliance is throughout the soil column.
(f) 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. See Article III (relating to air resources).
§ 250.408. 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 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) 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:
(1) Source characterization or development of a conceptual site model.
(2) The vertical and horizontal extent of contamination above the selected standard within each medium of concern.
(3) The direction and rate of contaminant movement within each medium of concern.
(4) Identification of the appropriate remedial technology options for each medium 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 medium 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 regulated substances above the selected standard shall be defined by an appropriate number of samples inside and outside of the area that exceeds the standard. Soil samples from the area with the anticipated highest levels of contamination shall be obtained, as appropriate, to determine the applicability of the proposed remedial action and handling and disposal requirements for that soil during remediation.
(e) If groundwater is determined to be a medium 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 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.
§ 250.409. 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.
§ 250.410. 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) 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) Adequate design plans and specifications sufficient to evaluate the proposed remedy.
(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.
(c) When a person proposes 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 cleanup plan.
(d) A cleanup plan is not required and no remedy is required to be proposed or completed if no current or future exposure pathways exist.
§ 250.411. Final report.
(a) For sites remediated under the site-specific standard, the person conducting the remediation shall submit a final report to the Department which documents attainment of the selected standard.
(b) Final reports shall demonstrate that the remedy has been completed in accordance with an approved cleanup plan.
(c) Final reports shall include the information identified in § 250.204(f)(1)--(5) (relating to final report).
(d) If engineering or institutional controls are needed to maintain a standard, if the fate and transport analysis indicates that the remediation standard 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).
(e) The comments obtained as a result of a public involvement plan and the responses to those public comments shall be included in a final report.
(f) If mitigation measures are implemented in accordance with § 250.311(f) (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 which shall be successfully accomplished and sustained up to 5 years from final report approval.
Subchapter E. SIA STANDARDS Sec.
250.501. Scope. 250.502. Eligibility determinations. 250.503. Remediation requirements. § 250.501. Scope.
(a) This subchapter sets forth requirements and procedures for any person who conducts remediation activities for property located in an SIA.
(b) A person who conducts remediation activities in an SIA shall comply with the requirements for notifying municipalities, the public and the Department.
§ 250.502. Eligibility determinations.
The person proposing remediation shall demonstrate:
(1) The property was used for industrial activity.
(2) The person did not cause or contribute to contamination on the property.
(3) There is no financially viable responsible person to clean up the contamination; or the property is located within a designated enterprise zone.
§ 250.503. Remediation requirements.
(a) A person proposing remediation of an SIA shall perform a baseline remedial investigation that establishes a reference point for existing contamination.
(b) A work plan shall be prepared that will define the scope of the baseline remedial investigation and shall be submitted to the Department for approval prior to the initiation of the investigation.
(c) At a minimum, a baseline remedial investigation shall include the following:
(1) Identification of the historical regulated substance use, handling and disposal activities on the property and any known or suspected releases associated with these activities by conducting environmental site assessment research and interviews with any person who may have knowledge of the property.
(2) If indicated by the investigation, performance of environmental sampling, within all potential media of concern, to confirm that the releases have occurred.
(3) Identification of potential migration pathways off the property and associated potential receptors of any confirmed releases on the property.
(4) If migration pathways and associated potential receptors have been identified, performance of environmental sampling of groundwater and other media at the downgradient property boundary to determine if regulated substances from the releases on the property have migrated off the property.
(5) Evaluation of exposure conditions within the portion of the property to be reused to identify existing contamination that poses an immediate, direct or imminent threat to public health or the environment which is inconsistent with the intended reuse of that portion of the property.
(d) The results of the baseline remedial investigation shall be included in a baseline environmental report. At a minimum, the baseline environmental report shall include the following:
(1) A description of the location and boundaries of the SIA.
(2) Identification of all areas of contamination.
(3) A description of the intended reuse of the property and exposure patterns.
(4) A remediation plan for the property that addresses all immediate, direct or imminent threats to public health and the environment which would prevent the property from being occupied for its intended purpose and delineates methods of compliance monitoring. At a minimum, immediate, direct or imminent threats will entail:
(i) Containerized wastes not intended in the property reuse, such as wastes in drums, above or below ground tanks and small containers.
(ii) Wastes not contained which present a direct threat to workers or other users or occupants of the property.
(iii) Contaminated soil presenting a direct threat to workers or other users or occupants of the property. The depth of consideration shall be the first 2 feet from the ground surface, unless reuse of the property presents exposure threats from depths greater than 2 feet.
(iv) Contaminated groundwater, if groundwater use will expose persons on the property to contaminants.
(v) Contaminated surface water and sediments, if use will expose persons on the property to contaminants.
(5) A remediation plan to prevent access to portions of the property containing contaminated media that is not being required to be remediated and that poses unacceptable health risks to trespassers or workers on the site.
(6) A description of the existing or potential public benefits of the reuse of the property, such as employment, housing, open space or recreation.
(7) The comments obtained as a result of a public involvement plan and the responses to these public comments.
(e) A person that changes the use of the property from nonresidential to residential, or changes the use of the property to create substantial changes in exposure conditions to contamination that existed prior to the person's reuse shall notify the Department of the changes and may be required to implement a remediation plan to address any new imminent, direct or immediate threats to human health and the environment resulting from the changes.
(f) The baseline environmental report shall include and address any municipal and public comments and the response to those comments as developed by the public involvement plan.
(g) The baseline environmental report shall be submitted to the Department after the date of approval of the baseline remedial investigation work plan, and the public participation period.
Subchapter F. EXPOSURE AND RISK DETERMINATIONS Sec.
250.601. Scope. 250.602. Risk assessment procedures. 250.603. Exposure factors for site-specific standards. 250.604. Fate and transport modeling requirements for exposure assessments. 250.605. Sources of toxicity information. 250.606. Development of site-specific standards. § 250.601. Scope.
(a) This subchapter specifies the information and procedures necessary to conduct a risk assessment.
(b) A risk assessment shall ensure adequate evaluation of the risks associated with human and ecological receptors exposed to regulated substances at contaminated sites.
(c) A risk assessment may include one or more of the following:
(1) A baseline risk assessment.
(2) A risk assessment to develop site-specific standards.
§ 250.602. Risk assessment procedures.
(a) Except as specified in § 250.405 (relating to when to perform a risk assessment), a person shall perform a risk assessment when using a site-specific standard under Subchapter D (relating to site-specific standards) to determine if there are unacceptable exposures to humans or unacceptable exposures to ecological receptors, or both.
(b) A person who proposes to perform a risk assessment under the site-specific standard shall use the methodologies used to develop the Statewide health standards contained in Subchapter C (relating to Statewide health standards) to conduct the risk assessment. If methodologies are not specified in Subchapter C or this subchapter, the risk assessment shall be conducted in accordance with the methodology specified in EPA or ASTM guidelines approved by the Department.
(c) A risk assessment for human exposure shall include the following components:
(1) Data collection, including source characterization and development of a conceptual site model, and evaluation to identify contaminants of concern.
(2) Exposure assessment that considers ingestion, inhalation and volatilization pathways and exposure assumptions based on land use.
(3) Toxicity assessment that includes the use of toxicity information from sources identified in § 250.605 (relating to sources of toxicity information).
(4) Risk characterization that evaluates if the risks meet the human health protection goals and ecological receptor protection specified in § 250.402 (relating to human health and environmental protection goals).
(d) An exposure assessment that is based on sampling shall use a data handling methodology that is consistent with the statistical method used to demonstrate attainment.
(e) When performing an exposure assessment, a person shall use the appropriate exposure factors identified in § 250.603 (relating to exposure factors for site-specific standards) and meet the requirements of § 250.604 (relating to fate and transport modeling requirements for exposure assessments).
(f) The risk assessment report shall discuss the degree of uncertainty associated with the risk assessment.
§ 250.603. Exposure factors for site-specific standards.
(a) A risk assessment for the site-specific standard shall use site-specific exposure factors under the EPA's Final Guidelines for Exposure Assessment, 1992 (57 FR 22888--22938) or exposure factors used in the development of the Statewide health standards identified in Subchapter C (relating to Statewide health standards).
(b) If a person uses site-specific exposure factors that deviate from the standard exposure factors in Subchapter C, the site-specific exposure factors shall be clearly justified by supporting data. The person shall provide the supporting data in the site-specific risk assessment report.
(c) The exposure factors shall be selected based on the land use of the site with reference to current and currently planned future land use and the effectiveness of institutional or legal controls placed on the future use of the land.
(d) The person shall document in the site-specific risk assessment report the future use of the site.
§ 250.604. Fate and transport modeling requirements for exposure assessments.
(a) A person may use the soil-to-groundwater model in § 250.308(a)(2) (relating to soil-to-groundwater pathway numeric values) to estimate site-specific, soil-to-groundwater leaching potential for organic contaminants if the following conditions are met:
(1) Site-specific values of water-filled soil porosity, dry soil bulk density, dilution factors (DF) and fraction organic carbon in soil beneath the source of contamination (that is, not from top soil) are appropriately justified and the person provides supporting data to the Department.
(2) Koc values as provided in § 250.308(a)(2) are used or site-specific values which are appropriately justified are used and the person provides supporting data to the Department.
(3) There is no identified separate phase liquid contamination at the site.
(4) Other processes such as colloidal transport or transport by means of dissolved organic matter (DOM) are not significant at the site.
(5) The application of the soil-to-groundwater model shall meet the most current EPA or ASTM quality assurance/quality control criteria approved by the Department.
(b) Except for the soil-to-groundwater model in § 250.308(a)(2), a person planning to use other fate and transport models and methods to estimate exposure concentrations and to develop site-specific standards shall use appropriate models or methods approved by the Department. The application of groundwater models shall meet the most current EPA or ASTM quality assurance/quality control criteria approved by the Department.
§ 250.605. Sources of toxicity information.
(a) For site-specific standards, the person shall use appropriate reference doses and cancer slope factors identified in Subchapter C (relating to Statewide health standards), unless the person can demonstrate that published data, available from one of the following sources, provides more current reference doses or cancer slope factors:
(1) Integrated Risk Information System (IRIS).
(2) Health Effects Assessment Summary Table (HEAST).
(3) United States Environmental Protection Agency, National Center for Environmental Assessment (NCEA) provisional values.
(4) Agency for Toxic Substances and Disease Registry (ATSDR) Toxicological Profiles.
(5) California EPA, California Cancer Potency Factors.
(6) EPA criteria documents, including drinking water criteria documents, drinking water health advisory summaries, ambient water quality criteria documents and air quality criteria documents.
(b) If no toxicity values are available from sources identified in subsection (a), the person may use the background standard or meet one of the following:
(1) Develop for the Department's review in the risk assessment report one of the following:
(i) Chemical-specific toxicity values in accordance with the methods in the most current EPA guidelines or protocols, approved by the Department, using corroborated peer-reviewed data published in a scientific journal, if they exist.
(ii) Toxicity values developed from appropriately justified surrogates.
(2) Use the minimum threshold medium-specific concentration, as the site-specific standard, with an assumed risk of 1 × 10-5 for purposes of calculating cumulative risk for the regulated substances identified in Appendix A, Table 6.
§ 250.606. Development of site-specific standards.
(a) If an unacceptable risk is identified by the assessments described in § 250.602 (relating to risk assessment procedure), a person shall perform one of the following:
(1) A remediation that eliminates all current and probable future exposure pathways.
(2) A remediation utilizing a standard developed under a site-specific risk assessment that is protective of human health and the environment.
(b) A person who chooses to use a standard developed under a site-specific risk assessment shall meet the human health and environmental protection requirements identified in § 250.402 (relating to human health and environmental protection goals).
(c) The development of site-specific standards shall be based on the standard in § 250.605(b)(2) (relating to sources of toxicity information) or the components of risk assessment in § 250.602, the appropriate exposure factors identified in § 250.603 (relating to exposure factors for site-specific standards), the fate and transport modeling requirements of § 250.604 (relating to fate and transport modeling requirements for exposure assessments) and the toxicity values of § 250.605 (relating to source of toxicity information).
(d) The following factors shall be considered in the development of the risk assessment and in the development of site-specific standards:
(1) Groundwater in aquifers.
(i) Natural environmental conditions that affect the fate and transport of contaminants, such as natural attenuation, shall be determined.
(ii) The person shall identify routes of exposure for aquifer groundwater such as human exposure to groundwater by ingestion, human inhalation of regulated substances from volatilization and migration of these substances into buildings or other areas where humans could be exposed, human ingestion of regulated substances in surface water or other site-specific surface water exposure pathways with respect to groundwater discharges or releases to surface water, human inhalation of regulated substances in air, or other site-specific air exposure pathways with respect to release of regulated substances from groundwater to air.
(2) Nonaquifer groundwater. The persons shall consider current and probable future exposure scenarios, such as human exposure as described in paragraph (1)(ii).
(3) The person shall consider current and probable future exposure scenarios, such as:
(i) Human ingestion of soil when direct contact exposure to the soil may reasonably occur.
(ii) Exposure to groundwater by ingestion with respect to leaching of regulated substances from soils to groundwater.
(iii) Human inhalation of regulated substances from volatilization and migration of these substances into below grade occupied space.
(iv) Human ingestion of regulated substances in surface water or other site-specific surface water exposure pathways with respect to regulated substances migration from soil to surface water.
(v) Human inhalation of regulated substances in air or other site-specific air exposure pathways with respect to the release of regulated substances from soil to air.
(4) If ecological receptors have been identified under § 250.311 (relating to evaluation of ecological receptors) or § 250.402, and are impacted, a remedial activity that eliminates current or future exposure pathways, or a standard, shall be developed to protect the receptors from the direct impacts.
(e) In determining soil and groundwater site-specific standards, the person shall identify the land use of the site with reference to current and currently planned future land use and the effectiveness of institutional or legal controls placed on the future use of the land.
(f) In determining soil and groundwater site-specific standards, the person shall use appropriate statistical techniques, including Monte Carlo simulations as appropriate, to establish statistically valid cleanup standards. The report for a risk assessment to develop site-specific standards shall discuss the degree of uncertainty associated with the risk assessment.
Subchapter G. DEMONSTRATION OF ATTAINMENT Sec.
250.701. Scope. 250.702. Attainment requirements. 250.703. General attainment requirements for soil. 250.704. General attainment requirements for groundwater. 250.705. Attainment requirements for groundwater in aquifers not used or currently planned to be used. 250.706. Demonstration of attainment of surface water and air quality standards. 250.707. Statistical tests. 250.708. Postremediation care attainment. § 250.701. Scope.
(a) This subchapter specifies the information and procedures necessary to demonstrate attainment with one or a combination of the background standard, Statewide health standard, site-specific standard and the minimum threshold standard, when a release of a regulated substance has occurred.
(b) This subchapter applies to persons who undertake a remediation in accordance with the act and this chapter.
(c) For purposes of determining attainment of one or a combination of remediation standards, the concentration of a regulated substance is not required to be less than the limits relating to the PQLs for a regulated substance in accordance with § 250.4 (relating to limits related to PQLs).
(d) Attainment of a standard shall be demonstrated at the point of compliance, as identified in § 250.203, 250.302 or 250.407 (relating to point of compliance), whichever is applicable.
§ 250.702. Attainment requirements.
(a) Attainment of a standard shall be demonstrated with adherence to Data Quality Objectives (DQO) and Data Quality Assessment (DQA) processes as specified by the EPA, as appropriate. Attainment of the Statewide health or site-specific standard will apply to the vertical and horizontal extent of soil identified as contaminated from the release of a regulated substance above the selected standard and of groundwater at the point of compliance and beyond in a site characterization. Attainment of the background standard will apply to the vertical and horizontal extent of soil and water identified as contaminated from the release across the site. Where multiple releases occur on a property which produce distinctly separate zones of contamination, the characterization and subsequent attainment demonstrations apply individually to the separate zones.
(b) Demonstration of attainment in a final report shall include the following:
(1) A demonstration that the analysis of the data, through the application of statistical tests provided for in § 250.707 (relating to statistical tests), indicates that the standard has been met.
(2) For groundwater, a demonstration of a statistical time trend analysis, knowledge of the plume stability or other acceptable method that shows contaminant concentration at the point of compliance will not exceed the selected standard. A statistical analysis shall be applied that indicates continued attainment of the standard.
(3) For the site-specific standard, the following apply:
(i) If pathway elimination is part of the remediation, it shall be demonstrated on the basis of either an engineering or hydrogeologic analysis, or both, which includes fate and transport analysis that some or all of the exposure pathways have been eliminated.
(ii) If pathway elimination is not part of the remediation or it cannot be demonstrated that all pathways have been eliminated, it shall be demonstrated that the calculated numerical site-specific standards for the remaining pathways have been attained in accordance with paragraphs (1) and (2), using the procedures in § 250.707(c) and (d), or that the risk level remaining at a site does not exceed a risk level of 1 × 10-4 and a hazard index of 1, provided for in the act. If separate phase liquids are present, it shall also be demonstrated that calculated site-specific numeric standards are attained within the soil and groundwater directly impacted by the separate phase liquids when those numeric standards are associated with exposure to separate phase liquids.
(4) For the background and Statewide health standards, if separate phase liquids are present, attainment at the point of compliance shall also be demonstrated within the soil and groundwater directly impacted by separate phase liquids.
§ 250.703. General attainment requirements for soil.
(a) For any standard selected, the attainment demonstration for the soil media shall be made at the point of compliance as defined in Subchapters B--D (relating to background standards; Statewide health standards; and site-specific standards).
(b) The volume of soil to which the attainment criteria is applied shall be determined by circumscribing with an irregular surface those concentrations detected during characterization which exceed the selected standard.
(c) Sampling points for demonstration of attainment of soils shall be selected to be random and representative both horizontally and vertically based on a systematic random sampling as set forth in a Department approved reference. If exceedances of a standard occur in a localized area, the Department may require additional characterization and remediation if three or more adjacent samples exceed the standard by more than ten times.
(d) For statistical methods under § 250.707(b)(1)(i) (relating to statistical tests), the number of sample points required for each distinct area of contamination to demonstrate attainment shall be determined in the following way:
(1) For soil volumes equal to or less than 125 cubic yards, at least eight samples.
(2) For soil volumes up to 3,000 cubic yards, at least 12 sample points.
(3) For each additional soil volume of up to 3,000 cubic yards, an additional 12 sample points.
(4) Additional sampling points may be required based on site-specific conditions.
(e) For statistical methods under § 250.707(b)(1)(ii) and (c), the minimum number of samples required for demonstrating attainment shall be as specified by the documentation of the chosen method.
§ 250.704. General attainment requirements for groundwater.
(a) For any standard selected, the attainment demonstration for the groundwater media shall be made at the point of compliance as defined in Subchapters B--D (relating to background standards; Statewide health standards; and site-specific standards).
(b) A sufficient number and location of monitoring wells necessary to demonstrate attainment of each plume of contamination shall be installed at the point of compliance for each aquifer based on site-specific conditions. Well locations shall be selected to yield an adequate amount of water to produce statistically valid results.
(c) In cases where the site characterization has determined the groundwater contamination (plume) extends beyond the property boundary, and the concentration of regulated substances beyond the property is above the cleanup levels of the standard selected, then the location and number of wells shall determine compliance:
(1) At and beyond the property boundary.
(2) Within the area of property shown, in the site investigation report, to be contaminated with regulated substances above the selected standard.
(d) For statistical methods under § 250.707(b)(2)(i) (relating to statistical tests), the demonstration of attainment for groundwater shall be based on at least eight consecutive quarters of groundwater data. As an alternative, the Department may accept four consecutive quarterly sampling events or less with written approval from the Department under the following conditions:
(1) There is adequate spatial monitoring of the plume upgradient which indicates a decreasing concentration trend toward the downgradient property boundary.
(2) Parameters affecting the fate and transport of regulated substances within the plume have been fully evaluated.
(3) Concentrations of regulated substances in the plume at the point of compliance monitoring wells along the downgradient property boundary are all less than or equal to the groundwater standard or the limit relating to the PQL, whichever is higher, in all samples collected during the quarters of monitoring.
(4) One of the following requirements are met:
(i) The age of the plume is sufficiently well known to permit a judgment to be made regarding its stability.
(ii) The remediation includes source removal or containment actions which would reduce the chemical flux into the plume.
(e) For statistical methods under § 250.707(b)(2)(ii) and (c), the minimum number of samples required for demonstrating attainment shall be as specified by the documentation of the chosen method.
§ 250.705. Attainment requirements for groundwater in aquifers not used or currently planned to be used.
In addition to sampling and statistical analyses that apply to attainment of the Statewide health standards for groundwater in this subchapter, attainment of the MSC for aquifers not used or currently planned to be used shall include the following:
(1) A scientifically valid and applicable fate and transport analysis, based on sufficient sampling and monitoring data to calibrate the model.
(2) Based on the fate and transport analysis in paragraph (1), a demonstration that the MSC for groundwater in an aquifer used or currently planned for use is not exceeded at and beyond all points on a radius of 1,000 feet, downgradient from the property boundary within a period of no more than 30 years.
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