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California Vional Water Quality ControBoard r" <br /> �- Central Valley Region zj <br /> v Karl E. Longley,ScD, P.E.,Chair .r:i'� <br /> Linda S.Adams Arnold <br /> Secreinn or 11020 Sun Center Drive 4200,Rancho Cordova,California 95670-6114 <br /> I Schwarzenegger <br /> Em lronmenla! Phone(916)464-3291 •FAX(916)464-4645 <br /> hit //www.waterboards.ca.gov/ceniralvallev I - - Governor <br /> Prorecnon P� B U (IF <br /> 1 <br /> ��FED <br /> 4 December 2008 <br /> ENVIRuNMEN i HEALTH <br /> Mr. Joe Aldridge, Remediation Manager PERM I T(SERVICES <br /> NuStar Energy L.P. <br /> 2330 North Loop 1604 West <br /> San Antonio, TX 78278 <br /> THIRD QUARTER 2008 GROUNDWATER MONITORING REPORT AND VERTICAL <br /> GROUNDWATER INVESTIGATION, NuSTAR TERMINALS STOCKTON FACILITY, <br /> 2941 NAVY DRIVE, STOCKTON, SAN JOAQUIN COUNTY <br /> Regional Water Quality Control Board, Central Valley Region (Regional Water Board) staff <br /> reviewed the 30 October 2008 Groundwater Monitoring Report, Third Quarter 2008 (Third <br /> QMR). Ash Creek Associates, Inc. (Ash Creek) prepared the Third QMR on behalf of NuStar <br /> Terminals Operating Partnership L.P. (NuStar) for the NuStar Terminals Stockton Facility <br /> located at 2941 Navy Drive in Stockton (Site). Groundwater monitoring at the Site is conducted <br /> pursuant to Monitoring and Reporting Program (MRP) 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 (COCs) 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), MTBE, tertiary butyl alcohol (TBA), and <br /> di-isopropyl ether (DIPE). <br /> Groundwater bearing units underlying the Site are subdivided into four progressively deeper <br /> units designated zones A through D. During the third quarter of 2008, depth to groundwater <br /> ranged from about 6 to 11 feet below ground surface (bgs). Ash Creek calculated that <br /> horizontal gradients ranged from 0.0013 feet per foot (ft/ft) to 0.0017 within each zone. <br /> Groundwater flowed in an east-southeasterly direction. Downward vertical gradients were <br /> prevalent between all the water bearing zones except for the C and D zones. The maximum <br /> downward gradient downgradient of the Site was calculated for the ACA-2A and ACA-2B well <br /> pair at 0.021 ft/ft. Historically, downward vertical gradients have been predominant between <br /> the water bearing units. <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 the third quarter 2008, however, <br /> the highest levels of dissolved-phase petroleum hydrocarbons were generally observed in <br /> ST/MW-1 and PS/P-12. Maximum concentrations in these two wells included TPHg and TPHd <br /> California Environmental Protection Agency <br /> ped Ren'cled Paper <br />