Subchapter D. SITE-SPECIFIC STANDARD

 (a)  This subchapter sets forth requirements and procedures for any person selecting the site-specific standards.

 (a)  Site-specific standards shall be developed that meet the human health and environmental protection goals specified in this section. The development of site-specific standards shall be based on a site-specific risk assessment, if required.

 (b)  The site-specific standard shall be a protective level that eliminates or reduces any risk to human health in accordance with the following:

   (1)  For known or suspected carcinogens, soil and groundwater cleanup standards shall be established at exposures which represent an excess upperbound lifetime risk of between 1 in 10,000 and 1 in 1 million. The cumulative excess risk to exposed populations, including sensitive subgroups, may not be greater than 1 in 10,000.

   (2)  For systemic toxicants, soil and groundwater cleanup standards shall represent the level to which the human population could be exposed on a daily basis without appreciable risk of deleterious effect to the exposed population. Where several systemic toxicants affect the same target organ or act by the same method of toxicity, the hazard index may not exceed one.

 (c)  In addition to any protection afforded under other requirements for meeting surface water and air quality standards under this chapter, direct impacts resulting from a release of regulated substances to the receptors identified in §  250.311(a) (relating to evaluation of ecological receptors) shall be assessed and addressed in the remedial investigation, risk assessment and cleanup plans.

 (d)  If a person is using the site-specific standard to protect ecological receptors under this subchapter or in accordance with §  250.311(e), the following shall be performed:

   (1)  An ecological risk assessment to determine if an impact has occurred or will occur if the release of a regulated substance goes unabated.

   (2)  An ecological risk assessment conducted in accordance with Department-approved EPA or ASTM guidance to establish acceptable remediation levels or alternative remedies based on current and future use that are protective of the ecological receptors.

   (3)  Implementation of the selected remedy, which may include mitigation measures under §  230.311(f), that is protective of the ecological receptors.

 (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).

 (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.

 (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.

 (a)  A regulated discharge to surface waters shall comply with the applicable provisions of Chapters 91—96, 97 (reserved) and 102—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).

 (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).

 (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.

 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.

 (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.

 (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.

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