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California Regional Water Quality Control Board <br /> l <br /> Central Valley Region �_,Y <br /> Karl E. Longley,ScD, P.E.,Chair <br /> Linda S.Adams Arnold <br /> Secretary,jor 11020 Sun Center Drive 1!200,Rancho Cordova,California 95670-6114 Schwarzenegger <br /> Environmental Phone(916)464-3291 •FAX(916)464-4645 Governor <br /> Protection http://www.waterboards.ca.gov/centrnay <br /> tcm 22 April 2009 <br /> APR 2 3 2009 <br /> Mr. Joe Aldridge, Remediation Manager ENVIROHMENTHE <br /> NuStar Energy L.P. PERMIT/SERA S7Fi <br /> 2330 North Loop 1604 West <br /> San Antonio, TX 78278 <br /> 2008 ANNUAL GROUNDWATER MONITORING REPORT AND VERTICAL <br /> GROUNDWATER INVESTIGATION RESULTS REPORT, NuSTAR TERMINALS <br /> STOCKTON FACILITY, 2941 NAVY DRIVE, STOCKTON, SAN JOAQUIN COUNTY <br /> Regional Water Quality Control Board, Central Valley Region (Central Valley Water Board) <br /> staff reviewed the 29 January 2009 Groundwater Monitoring Report, Fourth Quarter and <br /> Annual 2008 (Annual Report) and the 30 January 2009 Vertical Groundwater Investigation <br /> Results Report (Investigation Report). Ash Creek Associates, Inc: (Ash Creek) prepared the <br /> Annual Report on behalf of NuStar Terminals Operating Partnership L.P. (NuStar) for the <br /> NuStar Terminals Stockton Facility located at 2941 Navy Drive in Stockton (Site). Groundwater <br /> monitoring at the Site is conducted pursuant to Monitoring and Reporting Program (MRP) <br /> No. R5-2007-0818. <br /> NuStar and its predecessor have conducted monitoring at the Site since 1992. In 2002, <br /> gasoline releases occurred from aboveground storage tanks (AGTs) G 3301, G 3302, and <br /> D 1503. The principal contaminants of concern (CDCs) include total petroleum hydrocarbons <br /> as gasoline (TPHg), TPH as diesel (TPHd), benzene, toluene, ethylbenzene, and xylenes <br /> (collectively BTEX), tertiary amyl methyl ether (TAME), methyl tertiary butyl ether (MTBE), <br /> tertiary butyl alcohol (TBA), and di-isopropyl ether (DIPE). . <br /> Groundwater bearing strata underlying the Site are subdivided into four progressively deeper <br /> units designated zones A through D. During the fourth quarter of 2008, depth to groundwater <br /> ranged from about three to 11 feet below ground surface (bgs). Groundwater levels were <br /> highest in February and lowest in May. Ash Creek calculated that horizontal gradients ranged <br /> from 0.001 feet per foot (ft/ft) to 0.002 ft/ft within each zone. Groundwater flowed in an east- <br /> southeasterly direction. Downward vertical gradients prevailed between all the water bearing <br /> zones except for the C and D zones. The maximum downward gradient was calculated for the <br /> PS/WC-3S and PS/WC-3M well pair at -0.363 ft/ft. Downward vertical gradients were <br /> predominant between all water bearing units throughout 2008. <br /> One source area monitoring well, PS/MW-14, has historically contained separate phase <br /> hydrocarbons (SPH), so it was not usually sampled until August 2005, when SPH was no <br /> longer observed. PS/MW-14 has contained the highest concentrations of dissolved phase <br /> petroleum hydrocarbons since it has been sampled. During 2008, however, the highest levels <br /> California Environmental Protection Agency <br /> Ca Recycled Paper <br />