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17 -+•. f <br /> ICES <br /> PUBLI HEALTH SER pQ...N. <br /> ,Q �o <br /> SAN JOAQUIN COUNTY <br /> ENVIRONMENTAL HEALTH DIVISION y :< <br /> Ernest M. Fujimoto, M.D., M.P.H., Acting Health Officer ' <br /> 445 N. San Joaquin Street P. O. Boz 388 • Stockton, CA 95201-0388 C��rFpRa`P <br /> 209/468-3420 <br /> MID ice/ <br /> GEORGE.LECHICH Cory <br /> PO BOX 881 <br /> STOCKTON CA 95201 <br /> RE: Valley Showcase 913 SITE CODE: 1114 <br /> 913 W. Fremont St. j <br /> i <br /> 1 <br /> San Joaquin County Public.Health Services Environmental Health Division has reviewed the <br /> October 20, 1994 Second Quarter Monitoring Report (QMR Report) and the November 14, 1994 <br /> workplan for an overexcavation of the former UST location (Workplan). <br /> The QMR recommends that;laboratory analyses of ground water samples obtained.from MW-1 <br /> and MW-3 be discontinued based upon analytical results of non-detect at method detection limits <br /> for total petroleum hydrocarbons as gas (TPH-g) and Benzene, Toluene, Ethyl Benzene and <br /> Xylene (BTEX) for two consecutive quarters. PHS-EHD recommends that analytical results of <br /> sampling of MW-3 indicate that the plume is not present in this location at this time and that <br /> there is no upgradient source to account for the ground water contamination which is present at <br /> this site. Analytical sampling of MW-3 should occur at least every six months or if the gradient <br /> begins to flow towards this well to detect any change in the lateral extent of the plume. Depth <br /> to water measurements shall be obtained quarterly. PHS/EHD recommends an additional <br /> analytical sample after the overexcavation is complete before changing the schedule to twice a <br /> year. <br /> Analytical results of MW-1: indicate that groundwater contamination i$ not present in this <br /> location. During an inspection of the well sampling, however, a hydrocarbon odor was detected <br /> in the well water by the PHS/EHD Environmental Health Specialist. <br /> During sampling, precautions are taken to minimize the inadvertent volatilization of contaminants <br /> from the sample by the time they are analyzed by the lab. Sometimes, when the level of <br /> contamination is very low the contaminant escapes even though extreme care is taken to capture <br /> it. Therefore even though the laboratory may report a result of Non=Detect if an odor is detected <br /> in the field the well is still.:considered contaminated. PHS/EHD recommends that analytical <br /> sampling of MW-1 remain on a quarterly schedule along with the depth to water measurements. <br /> The Workplan.has proposed an overexcavation in order to reduce the possibility of continued <br /> leaching of contamination from the impacted soil which is present in the former UST location. <br /> The workplan states that the excavation may reach a depth of 15 feet and groundwater is present <br /> at 13.5 feet. The workplan does not mention any procedures for removal, storage, or disposal <br /> of the anticipated groundwater as it enters the overexcavation. Removal of water entering the <br /> 1 <br /> A Division of San Joaquin County Health Care Services <br />