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Eavxno G. Brvuwry Jr,. <br /> ei ova n <br /> W .i,w Roaaloua: <br /> Water Boards ENV1RONM6N' POieC}1pN <br /> Central Valley Regional Water Quality Control BoardJe``��D <br /> 25 February 2014 <br /> 6 Jp% <br /> Ms. Andrea Wing ENop OMITISEpV c �(H <br /> Shell Oil Products US <br /> 20945 South Wilmington Avenue <br /> Carson, CA 90810 <br /> CONCEPTUAL SITE MODEL, SHELL STOCKTON TERMINAL, 3515 NAVY DRIVE, <br /> STOCKTON, SAN JOAQUIN COUNTY <br /> California Regional Water Quality Control Board, Central Valley Region (Central Valley Water <br /> Board) staff reviewed the 15 November 2013 Conceptual Site Model(CSM) submitted by <br /> Conestoga-Rovers and Associates (CRA) on behalf of Shell Oil Products US (Shell) for the <br /> Shell Stockton Terminal at 3515 Navy Drive in Stockton (Site). The Site has been an operating <br /> fuel storage and distribution facility since the 1940s and is located in an industrial area on <br /> Rough and Ready Island in Stockton. Shell currently receives fuel products via the Shell <br /> Pipeline Corporation and stores gasoline, diesel, and ethanol at the Site. <br /> The CSM summarizes the Site history, past remedial activities, and distribution of constituents <br /> of concern remaining at the Site. There are 37 shallow groundwater wells and one deeper well <br /> at the Site. Depth to groundwater at the Site ranges from 10 to 15 feet below ground surface <br /> and flow is generally southwesterly. Since 1987 Shell has operated several remediation <br /> systems including liquid phase hydrocarbon recovery, groundwater extraction, soil vapor <br /> extraction, oxygen injection, dual phase extraction, and air sparge. Shell currently conducts <br /> monitored natural attenuation (MNA) at the Site. Shell concludes the groundwater <br /> concentration plumes are not migrating and concentrations are declining. In September 2013, <br /> the maximum concentrations of total petroleum hydrocarbons as diesel (TPHd), TPH as <br /> gasoline (TPHg), benzene, and methyl tert butyl ether (MTBE) were 4,600 micrograms per liter <br /> (Ng/L), 39,000 pg/L, 7,600 Ng/L, and 12,000 ug/L, respectively. <br /> Our comments are: <br /> 1. Central Valley Water Board staff concurs with the recommendation to conduct a <br /> sensitive receptor survey at the Site. By 30 April 2014, Shell needs to complete a <br /> sensitive receptor survey and submit the results. <br /> 2. Central Valley Water Board staff does not concur with the request to review the Site for <br /> case closure under the State Water Resources Control Board Low Threat Underground <br /> Storage Tank Case Closure Policy (LTCP). Although this is a petroleum release case, <br /> the LTCP was developed for underground storage tanks (UST) Sites and does not <br /> necessarily apply to aboveground storage tank sites. <br /> 3. The CSM includes estimates of when Site groundwater concentrations will reach water <br /> quality objectives (WQOs). Central Valley Water Board staff does not concur with the <br /> KARL E. LONGLEY SCID, P.E., CHAIR I PAMELA G. GREEDON P.E., BGEE, EXECUTIVE orrICER <br /> 11020 Sun Canter Drive 0200.Rancho Cordova,CA 95670 lwww.waterboards.ca.gov/cantralvalley <br /> �+aECY4LFaPpFP <br />