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ENVIRONMENTAL HEALTH DEPARTMENT <br /> SAN JOAQUIN COUNTY <br /> so._l.ea Unit Supervisors <br /> .G <br /> Donna K.Heran,R.E.H.S. Carl Borgrnan,R.E.H.S. <br /> Q- � •-� 304 East Weber Avenue, Third Floor <br /> Director Mike Huggins,R.E.H.S.,R.D.I. <br /> AlOlsen,R.E.H.S. Stockton, California 95202-2708 <br /> �,:'• Douglas W.Wilson,R.E.H.S. <br /> • o•., c Program Manager Telephone: (209) 468-3420 Margaret Lagorio, R.E.H.S. <br /> Laurie A.Cotulla,R.E.H.S. Robert McClellon,R.E.H.S. <br /> Program Manager Fax: (209) 464-0138 Mark Barcellos,R.E.H.S. <br /> JAIL 2 5 2005 <br /> CARL KNOWLES <br /> P O Box 640 <br /> WOODBRIDGE CA 95258 <br /> RE: 1140 W HAMMER LANE SITE CODE: 1124 <br /> STOCKTON CA <br /> San Joaquin County Environmental Health Department (EHD) is the lead agency providing the <br /> oversight of the investigation and cleanup of releases from underground storage tanks (UST) <br /> within San Joaquin County. EHD has a contract with California State Water Resources Control <br /> Board (SWRCB) to conduct a UST corrective action program. Your site was placed in the Local <br /> Oversight Program on 15 August 1989. <br /> To date, nine monitoring wells (MW) have been installed for site investigation. Soil and <br /> groundwater samples have been collected and analyzed from the 9 MWs. Historically, MW-5 has <br /> evidenced the highest contaminant concentrations. In addition to the 9 MWs, four soil borings in <br /> the area of MW-5 have been completed. Soil and groundwater grab samples were also collected <br /> from these borings. Due to the high concentrations of gasoline contaminants in the groundwater, <br /> site closure cannot be granted without further investigation and cleanup. <br /> The vertical extent of impacted groundwater has not been demonstrated. Soil boring DB1 a <br /> demonstrated the presence of poorly graded sand at 95 and 98 feet below ground surface (bgs). <br /> Groundwater in this sand interval should be sampled and analyzed to demonstrate the vertical <br /> extent of impacted groundwater in the area of MW-5. <br /> Impacted groundwater is not, and probably cannot be, delineated to the north and the northeast <br /> of MW-5. The groundwater grab sample collected from soil boring SBX1, north of MW-5, is not <br /> considered definitive as the sampling depth appears to have been too shallow and the sample <br /> was not collected from the main sand body in the saturated zone. <br /> The former MW-8 was interfering with roadwork being performed by the City of Stockton and was <br /> therefore destroyed under EHD permit and inspection. It was replaced by installing an additional <br /> well (MW-9) on the southeast corner of the intersection down-gradient of MW-5. With the <br /> combined data from MW-8 and MW-9, it would appear that the lateral extent of impacted <br /> groundwater in the main sand body, at approximately 50 feet bgs, is delineated in the down- <br /> gradient direction. <br /> EHD reviewed the Feasibility Study Report prepared by Ground Zero Analysis, Inc. with staff from <br /> the California Regional Water Quality Control Board (CRWQCB) on November 1, 2001. In that <br /> report four remedial alternatives for groundwater cleanup were evaluated. The remedial <br /> alternative selected by Ground Zero Analysis was Oxygen Release Compound (ORC). It has not <br /> been demonstrated to EHD that ORC is effective in groundwater cleanup in a reasonable amount <br /> of time. In an EHD letter dated November 7, 2001, EHD recommended that you consider <br /> remedial alternatives other than ORC. <br />