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APPENDIX B: USE OF SCREENING LEVELS FOR HISTORICAL PIPELINE PORTFOLIO—BAKERSFIELD TO RICHMOND SITES The Consistent Technical Approach(CTA; Geomatrix Consultants, Inc., 2005)1 specifies use of Central Valley Regional Water Quality Control Board(RWQCB) Water Quality Objectives (WQOs) as part of the site investigation process. WQOs are defined in the Water Quality Control Plan(Basin Plan).2 The Basin Plan notes that WQOs exist in either numerical or narrative form. Where numerical limits do not exist, a numerical limit interpreting the narrative WQO is available in the State Water Resources Control Board(SWRCB) Water Quality Goals document.3 For delineation purposes at all Historical Pipeline Portfolio—Bakersfield to Richmond(HPP-BTR) sites, including the subject of this report, the WQO for each constituent is the lowest, most-conservative published numerical value. In addition to WQOs, the San Francisco Bay RWQCB Environmental Screening Levels (ESLs), which were not available at the time of CTA development, have been added as an additional screening tool for delineation decision making.4 The CTA does not prescribe the criteria by which affected soil is delineated; therefore, to achieve alignment between soil and groundwater decision making, United States Environmental Protection Agency(EPA) Regional Screening Levels (RSLs; EPA, 2008)5 and San Francisco Bay RWQCB ESLs are used to evaluate soil laboratory analytical data. In the context of a soil and groundwater investigation, RSLs, ESLs, and WQOs are screening levels used to define the extent of affected soil and groundwater, and not to assess site-specific health or ecological risks or establish cleanup standards. Further, the presence of a constituent at a concentration above a screening level does not necessarily indicate risk to human health or the environment. Total petroleum hydrocarbons (TPH) analysis and commonly fuel fingerprinting are used to distinguish HPP-BTR related petroleum hydrocarbons from other sources. The analytes at HPP- BTR sites are constituents of crude oil: TPH; benzene, toluene, ethylbenzene, and total xylenes (BTEX); and polynuclear aromatic hydrocarbons. The hydrocarbons associated with the HPP- BTR have a specific chemical profile, are typically highly weathered, and BTEX compounds are rarely present. 1. Geomatrix Consultants,Inc.,2005. Technical Approach to Site Evaluation and Decision-Making,Historical Pipeline Portfolio, Central Valley Region. February. 2. RWQCB(Central Valley Region),2008. The Water Quality Control Plan(Basin Plan)for the Sacramento River Basin and San Joaquin River Basin. Fourth Edition(revised October 2007 with approved amendments). 3. State Water Resources Control Board,2008. A Compilation of Water Quality Goals. July. 4. RWQCB(San Francisco Bay Region),2008. Screening for Environmental Concerns at Sites with Contaminated Soil and Groundwater(Interim Final). May. 5. EPA,2008. Region 9 Preliminary Remediation Goals Regional Screening Level Table. hM2://www.epa.gov/reizionO9/sLiperftmd/priz/index.html. September. B—I She Benham Companies,LLC AWholly Owned Subsidiary From Scrertce ra Sa7vlrons