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uality Conol Board <br /> Californiaeg1Onal Water Q <br /> y„en <br /> Re ion <br /> At ` Central Valley P E ,chair. Arnoldn <br /> Karl E. <br /> �LOnge)' cD, Schwarzenegger <br /> SMain Office <br /> Gpvernor' <br /> Linda S. Adam' 464-464 <br /> 11020 Sun Cerner Drive �643y1 -FAX�(116)California 966'16611 <br /> Seoero I J111 Phone 016) —, <br /> P..m-nvmnew"i h„p../nvwwswaterboards ca gnv/ccntralvalley <br /> Proreow” J L� <br /> FGt?i y 0 2007 <br /> 2007 LIIVIRONIisi IOU” <br /> 28 February pERtii T 1SER\1ICES <br /> Mr. Jeff Whitworth <br /> Shell Oil Products US <br /> 20945 South Wilmington Avenue <br /> Carson, CA 90810 <br /> GROUNDWATER MONITORING AND SHELL STOCKTON TERMiNALAL REPORT 2006 MR3515 NAVYDR VE, <br /> — THIRD AND FOURTH QUARTERS, <br /> STOCKTON, SAN JOAQUIN COUNTY Re Tonal Water <br /> 2007 Groundwater Monitoring and Remediation Report, <br /> Staff of the Regional Water Quality Control Board, Central Valley Region g <br /> Board) has reviewed the ' February submitted by Cambria <br /> 2006 Semi-Annual Report— 3rd and 4th Quarters (Report) <br /> Environmental Technology, Inc. (Cambria) on behalf of Shell Oil Products US (Shell) for the <br /> Shell Stockton terminal located at 3515 Navy Drive in Stockton (Site). The Report is required <br /> by Monitoring and Reporting Program (MRP) No. R5-2005-0810- <br /> During this period depth to groundwater was observed between 10 to 15 feet below ground <br /> surface (bgs) and flowed to the south-southeast and was calculated at a gradient of <br /> approximately 0.03 feet/foot. The vertical gradient was calculated at-0.0271 feet/foot <br /> downwards. Soil and groundwater at the t <br /> e are polluted primarily with total petroleum <br /> hydrocarbons as gasoline (TPHg), TPH asdiesel (TPHd), benzene, and methyl tertiary butyl <br /> ether (MTBE). Maximum concentrations of these contaminants of concern (COCs) detected <br /> during this semi-annual oatn14 000 NglLlade TPHg nd MTBEat 33,000 at 26 000 NgIL9rams per liter (Ng/L), <br /> TPHd at 9,900 pglenzene <br /> An interim groundwater extraction system (GWE) is being operated at the site and pumps <br /> groundwater from source area well MW-1 at an average rate of 0.3 gallons per minute. The <br /> groundwater is stored in an onsite baker tank and vacuum trucks transport the water to Shell's <br /> Martinez refinery for recycling. Shell estimates that the GWE removed approximately 5 pounds <br /> (lbs) of TPHg, 1 Ib benzene, and 5 lbs MTBE between June and December 2006. <br /> Separate phase hydrocarbons (SPH) typically observed in well MW-1 in May 2006 has lot <br /> been observed since installation of a top loading pneumatic pump in July 2006. The position <br /> of the groundwater plumes appears to be relatively stable in lateral extent. MW28 and MW35 <br /> are two furthest down gradient monitoring wells chemical. Increasing TEPH (TPHd) <br /> concentrations are being observed in MW28 and presently equal the water quality objective <br /> (WQO) of 56 pg/L. In MW35, TPHd concentrations also exceed the WQO. MTBE <br /> concentrations, and tertiary butyl alcohol (TBA) concentrations are relatively stable. <br /> California Environmental Protection Agency <br /> ped Recycled Paper <br />