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California '�gional Water Quality Cor. A Board <br /> Central Valley Region _ <br /> K <br /> Karl E. Longley,SCD, P.E..Chair <br /> Linda S.Adams 11020 Sun Center Drive 9200 Rancho Cordova.California 9>67(�61 14 Arnold <br /> .Secretary for Phone(916)464-3291 •FAX(916)464-4645 Schwarzenegger <br /> Environmental Go+'e rnor <br /> Protecooi7 111111/h+++++ +vaterboards.ca.eov/cttntrahatley <br /> MD E <br /> 7 August 2008 <br /> AUG e 8 2008 <br /> Mr. Jeff Whitworth ENVIROMAENT HEALTH <br /> Shell Oil Products US PERMIT/SERVICES <br /> 20945 S. Wilmington Avenue <br /> Carson, CA 90810 <br /> REVIEW OF SOIL REMEDIAL ACTION REPORT, FORMER SHELL CENTRAL VALLEY <br /> CRUDE OIL PIPELINES, MOUNTAIN HOUSE NEIGHBORHOOD B, TRACY, SAN JOAQUIN <br /> COUNTY <br /> Staff of the Regional Water Quality Control Board - Central Valley Region (Regional Water <br /> Board) have reviewed the 17 June 2008 Remedial Action Report, Mountain House <br /> Neighborhood B (RAR) submitted by Science Applications International Corporation (SAIC) on <br /> behalf of Shell Oil Products US (Shell). The RAR was submitted to document remedial soil <br /> excavation and soil gas sampling activities at the former location of Shell crude oil pipelines <br /> within the Mountain House residential development in Tracy. <br /> Soil impacted with petroleum hydrocarbons was excavated from 12 areas in Neighborhood B. <br /> The excavations ranged from 8 feet to about 30 feet below ground surface (bgs). Soil was <br /> removed that was impacted by separate phase hydrocarbons (SPH), as evidenced by visual <br /> staining, or that exceeded a concentration of 5,000 milligrams per kilogram (mg/kg) Total <br /> Petroleum Hydrocarbons as crude oil (TPHcr), a remedial excavation goal provided by <br /> Regional Water Board staff. Approximately 35,000 cubic yards of soil were excavated from <br /> the site of which approximately 10,000 cubic yards of impacted soil was transported to <br /> Altamont Landfill in Altamont for disposal. The remaining excavated soil was segregated and <br /> stockpiled adjacent to the excavations for subsequent reuse as backfill. <br /> Confirmation soil samples were collected from the base and sidewalls of the excavations to <br /> document petroleum hydrocarbon concentrations remaining in place. Soil samples were <br /> analyzed for TPHcr and TPH as diesel (TPHd) using EPA Method 8015B, and benzene, <br /> toluene, ethylbenzene, and xylenes (BTEX) using EPA Method 8260B. Residual TPHcr and <br /> TPHd were reported at maximum concentrations of 6,900 mg/kg and 2,300 mg/kg, <br /> respectively in one soil sample at Area B9 (sample 139-136-34' collected at 34 feet bgs near the <br /> water table). However, of the remaining 116 confirmation samples collected, 113 were non- <br /> detect for TPH and 3 had detections near the reporting limits. BTEX compounds were not <br /> detected at concentrations greater than their respective reporting limits. The remedial <br /> excavations were backfilled to the pre-existing grade with soil segregated during excavation <br /> and soil imported from elsewhere within the Mountain House development. Soil backfill was <br /> analyzed for TPHcr, TPHd, and BTEX at a frequency of one four-point composite sample per <br /> 1,000 cubic yards to evaluate suitability for reuse. Maximum TPHcr and TPHd concentrations <br /> California Environmental Protection Agency <br /> Recrch"cl Paper <br />