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Californil egional Water Quality Cor )1 Board " <br /> Central Valley Region <br /> Robert Schneider,Chair <br /> Linda S.Adams Arnold <br /> Srcreror)_�or Sacramento Main Office Schwarzenegger <br /> nrret rnenoi 11020 Sun Center Drive 4200.Rancho Cordova.California 95670-6114 U Governor <br /> Prorecnen Phone(916)464-3291 •FAX(916)464-4615 � <br /> http://Nww.waterboards.ca.gov/centralvallcy ��(jWED <br /> I' <br /> A(IG 0 4 200 <br /> 2 August 2006 ENVIRQ 6 <br /> PERMI�HE4 LTH <br /> Mr. Jeff Whitworth S <br /> Shell Oil Products US <br /> 20945 S. Wilmington Avenue <br /> Carson, CA 90810 <br /> APPROVAL OF SOIL REMEDIAL ACTION PLAN, MOUNTAIN HOUSE NEIGHBORHOODS <br /> C AND D, FORMER SHELL CENTRAL VALLEY CRUDE OIL PIPELINES, TRACY, SAN <br /> JOAQUIN COUNTY <br /> Staff of the California Regional Water Quality Control Board, Central Valley Region (Regional <br /> Water Board) has reviewed the 20 June 2006 Remedial Action Work Plan, Former Shell <br /> Central Valley Crude Oil Pipelines, Neighborhoods C and D, Parcels 209-450-02, -11, -12, <br /> and -13, Tracy (Soil Removal Plan) submitted by Science Applications International <br /> Corporation (SAIC) on behalf of Shell Oil Products US (Shell). The Soil Removal Plan was <br /> submitted as a remedial action plan to address soil contamination in an area of planned <br /> residential and commercial development known as Mountain House Neighborhoods C and D. <br /> A remedial action plan is a decision document that typically provides a final plan for complete <br /> site cleanup. Therefore, the Soil Removal Plan is viewed as an interim remedial action that <br /> partially addresses this requirement. <br /> The Soil Removal Plan proposes remediation of soil polluted with petroleum hydrocarbons <br /> released from the former Shell crude oil pipeline beneath the planned development. Shell <br /> also proposes to collect soil vapor samples to evaluate the potential threat to indoor air quality <br /> of future buildings and soil samples for leachability testing to evaluate the potential threat to <br /> groundwater quality from remaining soil contaminants. The investigation findings will be <br /> summarized in a written report that will include an evaluation of the potential threat to <br /> groundwater and potential risk of soil vapor migration to indoor air following property <br /> redevelopment. Recommendations for further site activities will be made, if warranted, based <br /> on the investigation results. A remedial strategy for groundwater protection will be proposed in <br /> a separate work plan based on soil leachability data and groundwater data from future <br /> monitoring wells. <br /> Shell proposes to remediate shallow petroleum hydrocarbon impacted soil in thirteen areas <br /> along the former pipeline by excavation and offsite disposal. Soil will be excavated to depths <br /> ranging from 6 feet to 15 feet below ground surface (bgs) in the residential/commercial <br /> development areas and up to 27 feet bgs down to the water table in the proposed school area <br /> due to the more sensitive land use. Anticipated lateral dimensions of the excavations range <br /> from 10 feet by 10 feet in Area 13 to 80 feet by 35 feet in Area 11. The excavations are <br /> anticipated to generate approximately 12,000 cubic yards of soil. The initial focus will be on <br /> California Environmental Protection Agency <br /> ped Rect cled Pope r <br />