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California "-!gional Water Quality Con"ol Board <br /> Central Valley Region !I = <br /> Karl E. Longley, ScD, P.E.,Chair <br /> Linda S.Adams :%rnold <br /> �.c �.,101_l,/ 1. Sacramento Hain Office <br /> 11112(1 Sun Cenlcr Dm n2l)o-Rancho Cordova.California 9�67(F61 14 Schwarzenegger <br /> in <br /> l- �u�unnnvu��l Gnrrur <br /> !'rrr.mn Phone(916)464-129I •FAX(916)464-464 <br /> hlgrihcc+. aterboards.ca.guv/eentrah allec <br /> 5 June 2008 <br /> `1MEN I HEALN <br /> Ms. Shelby LathropE .I,�li l i�GRVICES <br /> ConocoPhillips Company <br /> 76 Broadway <br /> Sacramento, CA 95818 <br /> OXYGEN INJECTION PILOT STUDY REPORT, FORMER TOSCO BULK TERMINAL <br /> #10013, 3505 NAVY DRIVE, STOCKTON, SAN JOAQUIN COUNTY <br /> California Regional Water Quality Control Board, Central Valley Region (Regional Water <br /> Board) staff reviewed the 25 April 2008 Oxygen Injection Pilot Study Report (Report) <br /> submitted by SECOR International Incorporated (SECOR) on behalf of the ConocoPhillips <br /> Company (ConocoPhillips) for the former Tosco bulk fuel terminal site at 3505 Navy Drive in <br /> Stockton (Site). NuStar Energy currently owns and operates the Site. The Report documents <br /> the results of seven, bi-weekly pilot study oxygen injection events performed at the Site <br /> between December 2007 and March 2008, and includes data collected through 1 April 2008. <br /> Therefore, this is the three-month report. <br /> The hydrostratigraphy underlying the Site is described as consisting of three progressively <br /> deeper layers called the A, B, and C zones. The A zone occurs at depths of about 10 to 25 <br /> feet below ground surface (bgs), the B zone from 30 to 50 feet bgs, and the C zone from 55 to <br /> 75 feet bgs. Twelve oxygen injection points (IP-1 through IP-12) were installed in June 2007. <br /> IP-1 through IP-9 are in the A zone, and IP-10 through IP-12 are in the B zone. However, only <br /> six of the 12 injection points are reportedly being used during each injection event. About 150 <br /> cubic feet of oxygen have been injected into each well. ConocoPhillips estimates that a total of <br /> '1 ,b00 pounds of oxygen have been Injected. The objective of the pilot study is to maintain <br /> dissolved oxygen (DO) levels at 10 milligrams per liter (mg/L) or greater to enhance the <br /> biodegradation of residual COCs. <br /> Groundwater monitoring for the pilot study is conducted in eight monitoring wells (MW-2, MW- <br /> 8, MW-10. MW-14, MW-16, MW-17B, MW-19C, and MW-20). The first five of these wells <br /> monitor the A zone, and the other three monitor the B zone. ConocoPhillips proposed to <br /> conduct groundwater monitoring for geochemical parameters and petroleum related <br /> constituents in these eight wells at 60 days, three months, and six months following the start of <br /> oxygen injection. <br /> Pre- and post-injection groundwater monitoring for constituents of concern (CDCs), <br /> geochemical parameters, and DO concentrations was conducted on 13 December 2007, <br /> 19 February 2008, and 24 March 2008 in the 12 injection points, the eight monitoring wells, <br /> California Environmental Protection Agency <br /> C$ Rec l cled Raper <br />