[26 Pa.B. 3985]
[Continued from previous Web Page] (d) When a person proposes a remedy that relies on the cooperation or agreement of third parties in order for the remedy to be implemented, documentation of that cooperation or agreement shall be submitted as part of the cleanup plan.
(e) A cleanup plan is not required and no remedy is required to be proposed or completed if no current or future exposure pathways exist.
§ 250.410. 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)--(4) (relating to final report).
(d) If engineering or institutional controls are needed to maintain a standard, 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.
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 release on the property.
(4) If migration pathways and associated potential receptors have been identified, performance of environmental sampling of groundwater at the downgradient property boundary to determine if migration of 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) Protection from cleanup liability is available only to persons undertaking a reuse and who have entered into a consent order and agreement with the Department based on the baseline environmental report.
(f) 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.
(g) 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.
(h) 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. 250.607. Risk assessment of remediation alternatives. § 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.
(3) A risk assessment of the remediation alternatives.
§ 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 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 the most recent EPA or ASTM guidelines identified in subsection (g).
(c) A risk assessment for human exposure shall include the following components:
(1) Data collection, including source characterization or 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 modelling requirements for exposure assessments).
(f) The risk assessment report shall discuss the degree of uncertainty associated with the risk assessment.
(g) The references identified in subsection (b) 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.
§ 250.603. Exposure factors for site-specific standards.
(a) A risk assessment for the site-specific standard shall use site-specific exposure factors. If not generated on a site-specific basis, the person shall use exposure factors used in the development of the statewide health standards identified in Subchapter C (relating to statewide health standards).
(b) The person may not use site-specific exposure factors that deviate from the standard exposure factors in Subchapter C unless site-specific exposure factors are 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 modelling requirements for exposure assessments.
(a) A person may use the soil-to-groundwater model in § 250.307(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 § 250.307(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 nonaqueous phase liquid (NAPL) contamination at the site.
(4) Other processes such as colloidal transport or transport via 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 referenced in subsection (c)(1)--(3).
(b) Except for the soil-to-groundwater model in § 250.307(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 identified in EPA or ASTM guidelines referenced in subsection (c)(4)--(6). The application of groundwater models shall meet the most current EPA or ASTM quality assurance/quality control criteria referenced in subsection (c)(1)--(3).
(c) The references referred to in this section are as follows:
(1) Chapter 6 (relating to Models and Computers in Ground-Water Investigation) of EPA's Handbook, Ground Water, Volume II: Methodology, EPA/625/6-90/016b, July, 1991.
(2) EPA. ''Quality Assurance and Quality Control in the Development and Application of Ground-Water Models.'' EPA/600/R-93/011. September 1992. Office of Research and Development, Washington, D.C. 20460.
(3) ASTM E 978, Standard Practice for Evaluating Mathematical Models for the Environmental Fate of Chemicals.
(4) Groundwater models have been identified in the following documents:
(i) Section 3.5 of EPA's ''Superfund Exposure Assessment Manual,'' EPA/540/1-88/001, OSWER Directive 9285.5-1, April, 1988.
(ii) EPA. ''Selection Criteria for Mathematical Models Used in Exposure Assessments: Ground-Water Models,'' 600/8-88/075, 1988.
(iii) EPA. ''Groundwater Modeling: An Overview and Status Report,'' EPA/600/2-89/028 (NTIS PB89-229497). (Also available from International Ground Water Modeling Center, Institute for Ground-Water Research and Education, Colorado School of Mines, Golden, Colorado 80401).
(iv) National Academy of Sciences (NAS). ''Ground Water Models: Scientific and Regulatory Applications.'' National Academy Press, Washington, D.C. 1990.
(v) EPA. ''Ground Water Modeling Compendium, Second Edition.'' EPA-500-B-94-003. 1994. Resource Management and Information Staff, Office of Solid Waste and Emergency Response, Washington, D.C.
(vi) van der Heijde, P.M. ''Identification and Compilation of Unsaturated/Vadose Zone Models.'' EPA/600/R-94/028. 1994. R.S. Kerr Environmental Research Laboratory, Office of Research and Development, U. S. EPA, Ada, OK.
(vii) EPA. ''Compilation of Ground-Water Models.'' EPA/600/R-93/118.1993. Office of Research and Development, Washington, D.C. 20460.
(5) Surface water models are identified in the following documents:
(i) Section 3.4 of EPA's ''Superfund Exposure Assessment Manual,'' EPA/540/1-88/001, OSWER Directive 9285.5-1. April, 1988.
(ii) ''Selection Criteria for Mathmematical Models Used in Exposure Assessments: Surface Water Models'' Office of Health and Environmental Assessment. EPA/600/8-87/042. 1987.
(iii) ''Water Quality Assessment: A Screening Procedure for Toxic and Conventional Pollutants in Surface and Ground Water-Part I.'' EPA/600/6-85/002a. September 1985. Environmental Research Laboratory, EPA, Athens, GA 30613.
(iv) ''Water Quality Assessment: A Screening Procedure for Toxic and Conventional Pollutants in Surface and Ground Water-Part II.'' EPA/600/6-85/002b. September 1985. Environmental Research Laboratory, EPA, Athens, GA 30613.
(6) Air models are identified in the following documents:
(i) Section 3.3 of the EPA's ''Superfund Exposure Assessment Manual,'' EPA/540/1-88/001, OSWER Directive 9285.5-1. April, 1988.
(ii) ''Interim Final Air Superfund National Technical Guidance Series (NTGS). Volume IV: Procedures for Dispersion Modeling and Air Monitoring for Superfund Air Pathway Analysis.'' EPA/450/1-89/004. Office of Air Quality Planning and Standards, EPA, Research Triangle Park, NC.
(iii) ''Compilation of Air Pollutant Emission Factors. Volume I. Stationary Point and Area Sources, and Supplements (AP-42).'' Fourth Edition. Office of Air Quality Planning and Standards, EPA, Research Triangle Park, NC.
(iv) ''Guideline for Air Quality Models (Revised)'' (GAQM), EPA-450/2-78-027R, July, 1986. (40 CFR Part 51, Appendix W).
§ 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 standard), 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, identified in subsection (c), 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 4.
(c) The references referred to in subsection (b)(1)(i) are as follows:
(1) 51 FR 33992 ''Guidelines for Carcinogen Risk Assessment.'' September 24, 1986.
(2) 51 FR 34006 ''Guidelines for Mutagenicity Risk Assessment.'' September 24, 1986.
(3) 51 FR 34014 ''Guidelines for the Health Risk Assessment of Chemical Mixtures.'' September 24, 1986.
(4) 51 FR 34028 ''Guidelines for the Health Assessment of Suspect Developmental Toxicants.'' September 24, 1986.
§ 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), then a person shall perform one of the following:
(1) A remediation that eliminates all current and 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 as identified in §§ 250.5 and 250.6 (relating to aquifer determinations; and current use and future use of aquifer groundwater).
(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 releases of regulated substances from groundwater to air.
(2) Nonaquifer groundwater as determined by § 250.5. The person 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 human ingestion of soil when direct contact exposure to the soil may reasonably occur, exposure to groundwater by ingestion with respect to leaching of regulated substances from soils to aquifer groundwater, human inhalation of regulated substances from volatilization and migration of these substances into below grade occupied space, 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, 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 § 250.310 (relating to evaluation of ecological receptors) or § 250.402, and are directly 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.
§ 250.607. Risk assessment of remediation alternatives.
(a) A risk assessment of the remedial alternatives shall include an evaluation of the magnitude of long-term risks remaining after completion of the remedial action and an evaluation of short-term risks that may be posed to the community, worker or the environment during the implementation of the remedy.
(b) The risk assessment of remediation alternatives 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. Demonstration of attainment of surface water and air quality standards. 250.706. Statistical tests. 250.707. Postremediation 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 standard relating to a PQL for a regulated substance in accordance with § 250.7 (relating to standards related to PQLs).
(d) Attainment of a standard shall be demonstrated at the point of compliance, as identified in § 250.203, § 250.302 (relating to points of compliance) or § 250.406, whichever is applicable.
§ 250.702. Attainment requirements.
(a) Attainment will apply to the vertical and horizontal extent of soil and water identified as contaminated from the release above the selected standard in a site characterization. If 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 § 250.706 (relating to statistical tests), indicates that the standard has been met.
(2) A demonstration of a statistical 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.
(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, then 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 this subchapter, 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.
§ 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 standard; 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 randomly both horizontally and vertically.
(d) For statistical methods under § 250.706(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 over 125 cubic yards, at least twelve sample points.
(3) Additional sampling points may be required based on site-specific conditions.
(e) For statistical methods under § 250.706(b)(1)(ii) and (c), the minimum number of sample points 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 standard; statewide health standards; and site-specific standards).
(b) A sufficient number and location of monitoring wells necessary to demonstrate attainment shall be installed at the point of compliance for each aquifer, based on site-specific conditions.
(c) When two or more impacted aquifers underlie a property or site, attainment of the cleanup standard will be evaluated on each aquifer separately.
(d) For site plumes characterized with significant vertical migration within a single aquifer, one or more clusters of compliance points will be applied.
(e) In cases where the site characterization has determined the groundwater contamination extends beyond the property boundary (plume), 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:
(1) Determine compliance at and beyond the property boundary.
(2) Determine compliance within the area off property shown, in the site investigation report, to be contaminated with regulated substances above the selected standard.
(f) For statistical methods under § 250.706(b)(2)(i) (relating to statistical tests), for groundwater subject to remediation, the demonstration of attainment shall be based on at least eight consecutive quarters of groundwater data. The Department may accept no fewer than four consecutive quarterly sampling events under the following conditions:
(1) There is more than adequate spatial monitoring of the plume upgradient of the property 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 standard relating to the PQL-- whichever is higher--in all samples collected during the four quarters of monitoring.
(4) One of the following 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.
(g) For statistical methods under § 250.706(b)(2)(ii) and (c), the minimum number of sample points required for demonstrating attainment shall be as specified by the documentation of the chosen method.
§ 250.705. Demonstration of attainment of surface water and air quality standards.
A person shall demonstrate attainment with the surface water and the air by demonstrating compliance with the applicable State and Federal laws and regulations.
§ 250.706. Statistical tests.
(a) Application of statistical tests for the background standard shall be as follows:
(1) For regulated substances which are naturally occurring, or for non-naturally occurring substances for which a known background condition exists, the person shall compare the population of analytical results of background samples with a population of the medium of concern.
(i) Soil.
(A) The Department may require that the highest measurement from the area of concern is not greater than the highest measurement from the background area, that is, the nonparametric upper tolerance limit.
(B) In addition to clause (A), the Department may accept the use of the Wilcoxon rank-sum test (equivalent to the Mann-Whitney U test) for data from two populations, when less than 40% of the measurements in the background population as well as the sample population in the area of concern are nondetect data.
(C) The false-positive rate for a set of data applied to a statistical test may not be greater than 0.20. The minimum number of samples to be collected is ten from the background population and ten from each distinct area of contamination.
(D) The censoring level of nondetects (NDs) shall be the standard relating to the PQL.
(E) The application of a statistical method shall meet the criteria in subsection (c).
(ii) Groundwater for known upgradient release of a regulated substance.
(A) The Department may accept the use of the non-parametric tolerance intervals that are applied in accordance with the procedures in clauses (B)--(F) and (H)--(J).
(B) The upgradient concentration shall be determined by sampling in a background well shown on the basis of characterization to exhibit the highest concentration.
(C) The well shall be sampled over a period of eight quarters to provide eight samples.
(D) From these eight samples, the highest concentration for each regulated substance shall be selected as the upper tolerance limit.
(E) In each onsite well, eight samples shall also be collected during the same eight-quarter period.
(F) The upper tolerance limit shall be met in each onsite well. The maximum of data collected from each onsite well shall be at or below the upper tolerance limit.
(G) In lieu of clauses (D)--(F), the Department may accept a retesting strategy using nonparametric prediction limit in accordance with current EPA guidance (U. S. EPA, Office of Solid Waste Management Division. ''Statistical Analysis of Groundwater Monitoring Data at RCRA Facilities; Addendum to Interim Final Guidance, EPA, Washington, D.C. June 1992). For each regulated substance, the highest concentration of the eight background samples shall be selected as the upper prediction limit, as determined by the most current EPA guidance.
(H) The application of a statistical method for groundwater background standard shall meet the criteria in subsection (c).
(I) The censoring level of NDs shall be the standard relating to the PQL.
(J) In lieu of eight-quarter sampling in clauses (C) and (E), the Department may allow the eight samples to be taken during a period of four quarters, if the following criteria can be met:
(I) There is more than adequate spatial monitoring of the plume upgradient of the property on which the release occurred which indicates a stable plume condition.
(II) Parameters affecting the fate and transport of regulated substances within the plume have been fully evaluated.
(III) Coefficient of variation for the eight samples collected over a four-quarter period may not exceed 1.0 for metals, 1.0 for some specific organic compounds and 2.0 for other organic compounds.
(IV) The age of the plume is sufficiently well known to permit a judgment to be made regarding its stability and remediation of the source associated with the upgradient contamination is not currently or has not recently occurred.
(iii) Background groundwater conditions due to naturally occurring or areawide contamination.
(A) To use this subsection for areawide contamination, the person performing remediation shall demonstrate to the Department, in writing, that the site conditions are due to areawide contamination and shall obtain the Department's approval to use this subsection.
(B) A minimum of twelve samples shall be collected from any combination of monitoring wells, including upgradient locations, if all data collected is used in determination of background concentrations.
(C) The same number of samples shall be collected within and representative of the area of groundwater contamination (plume) onsite as were collected in the upgradient sampling for each sampling event.
(D) The samples from the upgradient wells and the wells in the plume onsite shall be collected at the same time.
(E) Sampling may be accelerated so that all samples are collected as quickly as possible so long as the frequency does not result in serial correlation in the data.
(F) The resulting values may be compared using non-parametric or parametric methods to test for the difference in the mean of the two data sets.
(G) The sampling results in the plume onsite may not have extreme values, when comparing with the sampling results in the background points.
(H) The application of a statistical method for groundwater background standard shall meet the criteria in subsection (c).
(I) The censoring level of NDs shall be the standard relating to the PQL.
(2) For non-naturally occurring substances for which there is no known background condition, the default background standard is the standard relating to the PQL as specified in § 250.7 (relating to standards related to PQLs). Attainment of standards relating to the PQLs shall be demonstrated using the statistical test specified in subsection (b) or other appropriate statistical method that the Department determines satisfies the criteria in subsection (c).
(b) The following statistical tests may be accepted by the Department to demonstrate attainment with standards relating to the PQLs, the statewide health and site-specific standards. The statistical test for soil shall apply to each distinct area of contamination. The statistical test for groundwater will apply to each well. Testing shall be performed individually for each regulated substance identified in the final report site investigation as being present at the site for which a person wants relief from liability under the act. The application of a statistical method shall meet the criteria in subsection (c).
(1) For soil attainment determination at each distinct area of contamination, subparagraph (i) or (ii) shall be met in addition to the attainment requirements in §§ 250.702 and 250.703 (relating to attainment requirements; and general attainment requirements for soil).
(i) Seventy-five percent of all samples collected for attainment purposes shall be equal to or less than the standard with no individual sample exceeding ten times the standard.
(ii) As applied in accordance with EPA approved methods on statistical analysis of environmental data, as identified in subsection (d), the 95% upper confidence level of the mean shall be at or below the standard.
(2) For groundwater attainment determination at each point of compliance, subparagraph (i) or (ii) shall be met in addition to the attainment requirements in § 250.702 and § 250.704 (relating to general attainment requirements for groundwater).
(i) Seventy-five percent of all samples collected for attainment purposes shall be equal to or less than the standard with no individual sample exceeding both of the following:
(A) Ten times the standard on the property.
(B) Two times the standard beyond the property boundary at the point of compliance.
(ii) As applied in accordance with EPA approved methods on statistical analysis of environmental data, as identified in subsection (d), the 95% upper confidence level of the mean shall be at or below the standard.
(c) Except for the statistical methods identified in subsection (b)(1)(i) and (2)(i), a demonstration of attainment with one or a combination of remediation standards shall comply with the following:
(1) When statistical methods are to be used for demonstration of attainment of standards relating to the PQLs, background standards after remediation, Statewide health or site-specific standards, the null hypothesis (Ho) shall be that the cleanup standard is not achieved, and the alternative hypothesis (Ha) shall be that the cleanup standard is achieved. When statistical methods are to be used to initially determine that the background standard other than standard relating to the PQL is exceeded, the null hypothesis (Ho) shall be that the background standard is achieved and the alternative hypothesis (Ha) shall be that the background standard is not achieved.
(2) A statistical method chosen shall comply with the following performance standards, as appropriate:
(i) The underlying assumptions of the statistical method shall be met, such as data distribution.
(ii) The statistical method shall be recommended for this use in a relevant Federal guidance or regulation and is generally recognized as appropriate for the particular remediation implemented at the site.
(iii) Compositing cannot be used with nonparametric methods.
(iv) Statistical parameters shall be protective of human health and the environment.
(v) Tests shall account for nondetects without assigning zero as the value.
(vi) Tests shall control for seasonal and spatial variability as well as temporal correlation of data.
(vii) Tests used to initially determine that the background standard is exceeded shall maintain adequate power (1-beta) to detect contamination in accordance with current EPA guidances, regulations or protocols.
(viii) For the standards relating to the PQLs, Statewide health and site-specific standards, the false-positive rate for a statistical test may not be greater than 0.20 for nonresidential and 0.05 for residential.
(ix) Testing shall be done individually for each regulated substance present at the site.
(3) The following information shall be documented in a final report when a statistical method is applied:
(i) A description of the statistical method.
(ii) A description of the underlying assumptions of the method.
(iii) Documentation showing that the sample data set meets the underlying assumptions of the method and explaining why the method is appropriate to apply to the data.
(iv) Specification of false positive rates.
(v) Documentation of input and output data for the statistical test, presented in tables, figures, or both, as appropriate.
(vi) An interpretation and conclusion of the statistical test.
(d) The references identified in subsection (b)(1)(ii) and (2)(ii) are as follows:
(1) U. S. EPA, Office of Policy, Planning and Evaluation, Methods for Evaluating the Attainment of Cleanup Standards, Volume 1: Soils and Solid Media, EPA 230/02-89-042, Washington, D.C. 1989.
(2) U. S. EPA, Office of Solid Waste Management Division, Test Methods for Evaluating Solid Waste, SW-846 Volume II: Field Methods, U. S. EPA, November 1985, Third Edition.
(3) U. S. EPA, Office of Solid Waste Management Division, Statistical Analysis of Groundwater Monitoring Data at RCRA Facilities, Interim Final Guidance, EPA, Washington, D.C., April, 1989.
(4) U. S. EPA, Office of Solid Waste Management Division, Statistical Analysis of Groundwater Monitoring Data at RCRA Facilities, Addendum to Interim Final Guidance, EPA, Washington, D.C., June, 1992.
(5) 40 CFR Parts 264 and 265 (relating to standards for owners and operators of hazardous waste treatment, storage, and disposal facilities; and interim status standards for owners and operators of hazardous waste treatment, storage, and disposal facilities).
§ 250.707. Postremediation attainment.
(a) After engineering controls are in place and the groundwater has reached a consistent concentration level, a statistical test shall be used to demonstrate that regulated substances in groundwater do not exceed the selected standard at the point of compliance. A statistical trend analysis, knowledge of the plume stability, or other acceptable method shall be used to demonstrate that contaminant concentration at the point of compliance will not exceed the selected standard in the future.
(b) If engineering or institutional controls are utilized at a site to maintain the nonresidential Statewide health standard or the site-specific standard, a post-remediation care program shall be implemented to protect human health and the environment.
(c) A person implementing engineering controls shall ensure the ongoing achievement of the performance standards in order to maintain attainment.
(d) A person shall implement a post-remediation care plan, as identified in an approved final report.
(e) A person may terminate post-remediation care as approved in the final report if he can demonstrate attainment under this chapter without the engineering controls in place.
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