ARCHIVED REPORTS_XR0009512 - Laserfiche WebLink

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PUBLIC HEALTH SERVICES U.l . SAN JOAQUIN COUNTY aENVIRONMENTAL HEALTH DIVISION Ernest M. Fujimoto, M.D., M.P.H., Acting Health Officer 445 N. San Joaquin Street • P. O. Box 388 • Stockton, CA 95202-0388 209/468-3420 C(D Q GEORGE LECHICH PO BOX 881 r 7 r STOCKTON CA 95201 RE: Valley Showcase 913 SITE CODE: 1114 913 W. Fremont St. San Joaquin County Public Health Services Environmental Health Division has reviewed the October 20, 1994 Second Quarter Monitoring Report(QMR Report) and the November 14, 1994 workplan for an overexcavation of the former UST location (Workplan). The QMR recommends that laboratory analyses of ground water samples obtained from MW-1 and MW-3 be discontinued based upon analytical results of non-detect at method detection limits for total petroleum hydrocarbons as gas (TPH-g) and Benzene, Toluene, Ethyl Benzene and Xylene (BTEX) for two consecutive quarters. PHS-EHD recommends that analytical results of sampling of MW-3 indicate that the plume is not present in this location at this time and that there is no upgradient source to account for the ground water contamination which is present at this site. Analytical sampling of MW-3 should occur at least every six months or if the gradient begins to flow towards this well to detect any change in the lateral extent of the plume. Depth to water measurements shall be obtained quarterly. PHS/EHD recommends an additional analytical sample after the overexcavation is complete before changing the schedule to twice a year. Analytical results of MW-1 indicate that groundwater contamination is not present in this location. During an inspection of the well sampling, however, a hydrocarbon odor was detected in the well water by the PHS/EHD Environmental Health Specialist. During sampling, precautions are taken to minimize the inadvertent volatilization of contaminants from the sample by the time they are analyzed by the lab. Sometimes, when the Ievel of contamination is very low the contaminant escapes even though extreme care is taken to capture it. Therefore even though the laboratory may report a result of Non-Detect if an odor is detected in'the field the well is still considered contaminated. PHS/EHD recommends that analytical sampling of MW-1 remain on a quarterly schedule along with the depth to water measurements. The Workplan has proposed an overexcavation in order to reduce the possibility of continued leaching of contamination from the impacted soil which is present in the former UST location. The workplan states that the excavation may reach a depth of 15 feet and groundwater is present at 13.5 feet. The workplan does not mention any procedures for removal, storage, or disposal ' of the anticipated groundwater as it enters the overexcavation. Removal of water entering the A Division of San Joaquin County Health Care Services