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• • <br /> l M11 iuinr.m�..•'ru4uen .n <br /> ..........�0 <br /> Water Boards <br /> Central Valley Regional Water Quality Control Board <br /> Mr. Jay Utal 30 October 2012 <br /> Nextbay Properties, LLC <br /> 3000 Danville Boulevard <br /> Alamo, CA 94507 <br /> WORK PLAN REVIEW, TRAILS OF MANTECA, 2368 EAST WOODWARD AVENUE, <br /> MANTECA, SAN JOAQUIN COUNTY <br /> Regional Water Quality Control Board, Central Valley Region (Central Valley Water <br /> Board) staff reviewed your 25 October 2012 Work Plan for Soil and Groundwater <br /> Assessment(Work Plan) submitted on your behalf by ENGEO, Inc. (ENGEO). The <br /> Work Plan was submitted in response to our 24 October 2012 letter requesting further <br /> site investigation at the Trails of Manteca site located at 2368 East Woodward Avenue <br /> in Manteca (Site). <br /> In 2005, elevated concentrations of diesel were detected in soil and groundwater <br /> adjacent to an above-ground storage tank (AST). In 2008, the diesel impacted soil was <br /> excavated; however, the groundwater was not sampled to evaluate if residual <br /> groundwater hydrocarbon contamination remains. <br /> ENGEO proposes to collect soil samples on a grid pattern around the AST area by <br /> advancing 10 soil borings to 25 feet below ground surface (bgs). At the boring <br /> proposed in the center of the excavation footprint, soil samples will be collected at 11, <br /> 16, and 25 feet bgs. If ENGEO observes elevated Photo-Ionization Detector (PID) <br /> readings at 25 feet, the boring will be advanced further until PID readings indicate no <br /> further impact and a soil sample will be collected at that depth. Three soil samples will <br /> be submitted for analysis of Total Petroleum Hydrocarbons as gasoline (TPHg), TPH as <br /> diesel (TPHd), TPH as motor oil (TPHmo), TPHd and TPHmo with silica gel filtration <br /> preparation, and Volatile Organic Compounds (VOCs). <br /> At the three borings along the edge of the excavation footprint, soil samples will be <br /> collected at 5 and 15 feet bgs. Six soil samples will be submitted for the same analyses <br /> as mentioned previously. <br /> At the six step-out borings, surface samples will be collected at three locations and at <br /> two locations samples will be collected at 5 feet bgs. These five samples will be <br /> analyzed for polychlorinated biphenyls (PCBs). Based on PID readings, four additional <br /> samples will be collected from these step-out borings and analyzed for TPHg, TPHd, <br /> TPHmo, TPHd and TPHmo with silica gel filtration preparation, and VOCs. <br /> LONOL=_v SCO, P.E.. CHAR I PAMELA C. CRCCOON P.C.. OCEE. Cx CCUTNE OFRCEP <br /> 11090 Grn c?m=r DIN.0200.RaOC'10 Conbva.CA 95610 1www wTRrt100rtl5 ca 9oa/cenVPivaxey <br /> Ci n c*cunr.—, <br />