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California gional Water Quality Con* Board <br /> \� Central Valley Region ib <br /> Kathrin Hart,Chair <br /> Linda S.Adams �l ScArnold <br /> Secretaryfor u <br /> 11020 Sun Center Drive#200,Rancho Cordova, ' � V D Arnold <br /> Environmental Phone(916)464-3291 •FAX(916) C Governor <br /> Protection http://www.waterboards.ca.gov/cen a�4 <br /> „y ,Y16L010 <br /> ENVIRUNNIN T HEMWiune 2010 <br /> Ms. Shelby Lathrop PERMIT/SERVICES <br /> ConocoPhillips Company <br /> 76 Broadway <br /> Sacramento, CA 95818 <br /> FIRST QUARTER 2010 STATUS SUMMARY REPORT AND REMEDIAL ACTION PLAN, <br /> FORMER TOSCO BULK TERMINAL #10013, 3505 NAVY DRIVE, STOCKTON, SAN <br /> JOAQUIN COUNTY <br /> California Regional Water Quality Control Board, Central Valley Region (Central Valley Water <br /> Board) staff reviewed the 29 April 2010 First Quarter 2010 Status Summary Report (First QMR) <br /> submitted on behalf of the ConocoPhillips Company (ConocoPhillips) by Stantec Consulting <br /> Corporation (Stantec) for the former Tosco bulk fuel terminal at 3505 Navy Drive in Stockton <br /> (Site). ConocoPhillips conducts groundwater monitoring at the Site pursuant to Monitoring and <br /> Reporting Program No. R5-2004-0824. NuStar Energy (NuStar) currently owns and operates <br /> the Site. <br /> Groundwater underlying and downgradient of the Site is polluted with low levels of contaminants <br /> of concern (CDCs), including total petroleum hydrocarbons as diesel (TPHd), tertiary butyl <br /> alcohol (TBA), methyl tertiary butyl ether (MTBE), TPH as gasoline (TPHg), and di-isopropyl <br /> ether (DIPE). Monitoring for the first quarter was conducted on 3 February 2010. TPHd <br /> concentrations ranged from 68 to 200 micrograms per liter (Ng/L), and TBA concentrations <br /> ranged from 35 to 120 pg/L. The highest concentration of MTBE was 13 pg/L. In some wells, <br /> these contaminant concentrations are within the range of historical variations that immediately <br /> preceeded and followed implementation of a mobile oxygen injection pilot study at the Site in <br /> December 2007. In previously highly polluted wells, such as MW-2 and MW-8, TBA <br /> concentrations have decreased substantially. <br /> After failing to sustain substantial increases in dissolved oxygen (DO) concentrations or observe <br /> consistent reductions in COC concentrations after about six months of implementing the pilot <br /> study, ConocoPhillips increased the volume of oxygen injections from 150 cubic feet (ft) to <br /> 300 ft3 per bi-weekly event in May 2008. ConocoPhillips has continued this schedule and <br /> estimates that about 2,937 pounds of oxygen have been injected at the Site since the pilot <br /> study began. During the first quarter 2010, oxygen injections and DO measurements were not <br /> performed in MW-22 due to a damaged screen. Distinct increases in DO concentrations to as <br /> much as 46.12 milligrams per liter (mg/L) were observed in the MW-17 and MW-20 clusters, <br /> which is higher than previous monitoring events. However, elevated concentrations of methanol, <br /> ranging from 1,200 mg/L in MW-19C to 60,000 mg/L in MW-17B were observed during the first <br /> quarter monitoring event. Central Valley Water Board staff previously concurred with <br /> ConocoPhillips' recommendation to extend the pilot study to the first quarter of 2010. <br /> California Environmental Protection Agency <br /> (a Recycled Paper <br />