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Californiagegional Water Quality Corp1 Board <br /> Central Valley Region ° <br /> .. <br /> Katherine Hart, Chair ` <br /> oa <br /> 1685 E Street,Fresno,California 93706 <br /> (559)445-5116•FAX(559)445-5910 Edmund G.Brown Jr. <br /> Matthew Rodriquez http://www.waterboards.ca.gov/centralvalley Governor <br /> Secretaryfor <br /> Environmental Protection <br /> 21 September 2011 <br /> r SEP 26 2011 <br /> Lee Higgins ENVIRQNMENTaLHEALTH <br /> Chevron Environmental Management Company PERMITISERVICES , <br /> 6001 Bollinger Canyon Road <br /> P. O. Box 6012 <br /> San Ramon, CA 94583 <br /> REVIEW — EXCAVATION COMPLETION REPORT AND UPDATED SCREENING LEVEL <br /> RISK ASSESSMENT, 990 BEECHNUT AVENUE, TRACY, SAN JOAQUIN COUNTY <br /> Chevron Environmental Management Company (Chevron) submitted the Excavation <br /> Completion Report (Report) and Updated Screening Level Risk Assessment (SLRA), 990 <br /> Beechnut Avenue, Tracy (Site) dated 23 December 2010. The Report was prepared for <br /> Chevron by AMEC-Geomatrix (AMEC) and submitted to Central Valley Regional Water Quality <br /> Control Board (Central Valley Water Board) staff for review. <br /> The Site was part of the former Tracy Pump Station and crude oil storage facility previously <br /> owned/operated by Chevron predecessors as part of the historical Old Valley Pipeline (OVP) <br /> and Tidewater Associated Oil Company (TAOC) pipeline conveyance system. The historical <br /> pipelines transported Kern County crude oil to Richmond refineries from the early 1900's to <br /> the early 1970's at which time the historical pipelines and pump station/storage equipment <br /> were removed from service. <br /> Currently, and unrelated to the excavation activities, Chevron is evaluating residual petroleum <br /> hydrocarbons present in shallow soil in two other areas in the northern part of the Site. <br /> Central Valley Water Board staffs' current review only addressed the excavation/soil removal <br /> portion of the Report. The SLRA update will be addressed at a later date after Chevron <br /> conducts additional evaluation and/or characterization related to the residual petroleum <br /> hydrocarbons remaining in the northern part of the Site. <br /> On 19 August 2010 Central Valley Water Board staff approved the Revised Excavation <br /> Workplan for removal of shallow soil affected by total petroleum hydrocarbons as crude oil <br /> (TPHc) compounds. The focus of the excavation was along the southwest boundary of the <br /> Site where high concentrations of TPHc and polynuclear aromatic hydrocarbons (PAHs) were <br /> detected in soil from a boring sample collected at 5.5 feet below ground surface (bgs). To <br /> better outline the planned affected soil removal, pre-excavation borings were drilled during <br /> May - July 2009 and March 2010 to collect samples for analysis. Soil samples were obtained <br /> in August 2010 from an onsite soil mound to characterize the soil for re-use as backfill. <br /> AMEC's Revised Workplan dated 17 August 2010 outlined the remedial goals for PAHs, <br /> naphthalene, and TPHc in accordance with likely future commercial and/or industrial land use <br /> California Environmental Protection Agency <br /> Za Recycled Paper <br />