Subchapter B. BACKGROUND STANDARD
Sec.
250.201. Scope.
250.202. Establishing background concentrations.
250.203. Points of compliance.
250.204. Final report.
Cross References This subchapter cited in 25 Pa. Code § 250.2 (relating to application of remediation standards); 25 Pa. Code § 250.9 (relating to interaction with other environmental statutes); 25 Pa. Code § 250.703 (relating to general attainment requirements for soil); and 25 Pa. Code § 250.704 (relating to general attainment requirements for groundwater).
§ 250.201. Scope.
This subchapter sets forth requirements and procedures for a person selecting the background standard, as provided in § 250.2 (relating to application of remediation standards).
§ 250.202. Establishing background concentrations.
(a) Background concentrations shall be established based on a site characterization, as set forth in § 250.204(a)—(e) (relating to final report).
(b) The background concentrations shall be established using analysis of samples of regulated substances present at the property but not related to any release at the property. If all areas on the property are affected by a release, background shall be determined at points off the property in accordance with § 250.204(f)(7) and (8).
(c) Background concentrations shall be established by a methodology that is statistically valid and consistent with the methodology used to demonstrate attainment under Subchapter G (relating to demonstration of attainment).
Cross References This section cited in 25 Pa. Code § 271.1 (relating to definitions); and 25 Pa. Code § 287.1 (relating to definitions).
§ 250.203. Points of compliance.
(a) For attainment of the background standard for groundwater, the point of compliance shall be throughout the contaminant plume, including areas of the plume that are outside the property boundary, as determined by the site characterization.
(b) For attainment of a background soil standard, the point of compliance shall be throughout the area of the soil that has become contaminated as a result of releases on the property.
(c) For attainment of a surface water quality standard, compliance shall be measured for point source discharges at the point of discharge in accordance with limits specified in the NPDES permit.
(d) For the emission of regulated substances to outdoor air, the point of compliance for any applicable air quality standard shall be as specified in the air quality regulations in Subpart C, Article III (relating to air resources).
Cross References This section cited in 25 Pa. Code § 250.701 (relating to scope).
§ 250.204. Final report.
(a) For sites remediated under the background standard, the person conducting the remediation shall submit a final report to the Department which documents attainment of the selected standard. The final report shall include site characterization information in subsections (b)—(e). The site characterization shall be conducted in accordance with scientifically recognized principles, standards and procedures. The level of detail in the investigation, and the selected methods and analyses, that may include models, shall sufficiently define the rate of movement and the present and future extent and fate of contaminants to ensure continued attainment of the remediation standard. Interpretations of geologic and hydrogeologic data shall be prepared by a professional geologist licensed in this Commonwealth.
(b) As derived 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 the following:
(1) Source characterization or development of a conceptual site model.
(2) The vertical and horizontal extent of contamination within each media of concern.
(3) The direction and rate of contaminant movement and fate and transport of all contaminants within each media of concern.
(4) A determination of the appropriate remedial technology for each media of concern.
(c) Descriptions of sampling and decontamination methodologies and analytical quality assurance/quality control procedures should be included within a Sampling and Analysis Plan and Quality Assurance Plan. Copies of soil and geologic boring descriptions and as-built construction drawings of wells used for site characterization should be included in the report. Copies of laboratory analytical results and applicable laboratory quality control results should be included within the report, including historical data and data eliminated from consideration based on data validation protocols. Analytical results should be presented within the report in table form.
(d) If soil is determined to be a media of concern, the site characterization shall determine the relative location of soil samples necessary to characterize the horizontal and vertical extent of contamination based on factors such as hydraulic conductivity of the soils, heterogeneity of the soils and the nature of the contaminants. 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 or handling and disposal requirements, or both, for that soil during remediation.
(e) If groundwater is determined to be a media of concern, the site characterization shall characterize the effects of a release on groundwater to adequately determine how naturally occurring physical and geochemical characteristics define the movement of groundwater and contaminants beneath the surface, including the delineation of the position of aquifers, as well as geologic units which inhibit groundwater flow. The site characterization shall meet the following conditions:
(1) If 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 any influence from pumping wells.
(2) 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 a sufficient number of days apart to yield independently valid results.
(3) 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.
(4) 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 such as zones directly above a confining layer. Samples shall be taken a sufficient number of days apart to yield independently valid results.
(f) Final reports for the background standard shall include the following additional information:
(1) Descriptions of treatment, removal or decontamination procedures performed in remediation. The description shall include the methodology and analytical results used to direct the remediation and determine the cessation of remediation.
(2) Descriptions of the sampling methodology and analytical results, including the appropriate statistical methodologies, which pertain to whether the remediation has attained the selected standard, following the requirements of Subchapter G (relating to demonstration of attainment).
(3) Documentation of compliance with postremediation care requirements, if they are needed to maintain the selected standard.
(4) All sampling data.
(5) For fate and transport analyses, submission of the following information:
(i) The name and version of the analysis, a description of the analysis, and the name of the organization or person which developed the analysis, if modeling is used.
(ii) The site characterization data used in the analysis.
(iii) Any assumptions used in the analysis and justification for the assumptions.
(iv) Appropriate documentation of the quality assurance and quality control of the analysis.
(v) Documentation of the results of the analysis in appropriate figures and tables.
(6) A summary of sampling methodology and analytical results that relate to the determination of the background concentration. The summary shall contain the following:
(i) For soil, the final report shall identify the background reference region within which all background samples were collected.
(ii) For groundwater, the final report shall identify background reference wells.
(7) Documentation that background reference areas for soil meet the following criteria:
(i) The background reference region and background reference areas shall be free of contamination from any release at the site.
(ii) Sampling at the background reference area and the contaminated area shall be comparable and random.
(iii) A background reference area selected for comparison with a given contaminated area may not differ significantly from that contaminated area in physical, chemical or biological characteristics that might cause measurements in the background reference area and the contaminated area to differ.
(8) Documentation that background reference groundwater concentrations have been determined at hydrogeologically upgradient points that characterize the groundwater flow onto the site that are not affected by any release at the property.
(g) If engineering controls are needed to attain or maintain a standard, if institutional controls are needed to maintain a standard, if the fate and transport analysis indicates that the remediation standard 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. The plan shall include the following:
(1) Reporting of any instance of nonattainment.
(2) Reporting of measures to correct nonattainment conditions.
(3) Monitoring on a quarterly basis, or as otherwise approved by the Department, that demonstrates the effectiveness of the remedy and periodic reporting of monitoring results and analysis.
(4) Maintenance of records at the property where the remediation is being conducted for monitoring, sampling and analysis.
(5) A schedule for operation and maintenance of the controls and submission of proposed changes.
(6) If requested by the Department, documentation of financial ability to implement the remedy and the postremediation care plan.
Cross References This section cited in 25 Pa. Code § 245.312 (relating to remedial action); 25 Pa. Code § 245.313 (relating to remedial action completion report); 25 Pa. Code § 250.202 (relating to establishing background concentrations); 25 Pa. Code § 250.312 (relating to final report); 25 Pa. Code § 250.411 (relating to final report); and 25 Pa. Code § 253.1 (relating to definitions).
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