SITE INFORMATION AND CORRESPONDENCE

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ERVICES BLIHF�ALH S SAN JOAQUIN COUNTY ur s ENVIRONMENTAL HEAL'T'H DIVISION Karen Furst, M.D., M.PH., Health Officer 304 East Weber Avenue,Third Floor • Stockton, CA 95202 Fo 2091468-3420 JESS CERVANTES DEC 0 6 2001 P O BOX 6008 STOCKTON CA 95206 RE: JC Trucking SITE CODE: 2571 1207 Aurora Street Stockton CA 95206 San Joaquin County Public Health Services, Environmental Health Division (PHSIEHD) has reviewed the"Site Assessment Report"dated November 14, 2001, and the"Quarterly Groundwater Monitoring and Sampling Report'dated October 14, 2001, that were prepared by JJW Geosciences Inc. on your behalf and has the following comments. The Site Assessment Report documents site fieldwork that took place in April and May of 2001. The objectives of the work were to define the lateral extent of the shallow groundwater contaminant plume, and to define the vertical extent of the plume. Initially, six geoprobe direct push borings were advanced to first encountered ground water and grab water samples were collected. The water samples were analyzed by an on-site mobile laboratory, and the data obtained was used to determine the locations of two additional shallow groundwater monitoring wells. Following the geoprobe investigation, six soil borings were advanced with a hollow stem auger drill rig. Two of the borings, MW-9 and MW-10, were converted to shallow groundwater monitoring wells. Two of the borings, MW-7A and MW-11,were converted to deep groundwater monitoring wells built to 110-feet below surface grade (bsg). One of the borings, MW-12,was advanced to 130-feet bsg and a deeper monitoring well was built to this depth. The final goring, SB-2,was advanced up-gradient to the site for the purpose of soil and groundwater sample collection only; no monitoring well was placed in this location. Though it was not mentioned in the report, a simulprobe discrete water sampling device was used to collect water samples from the borings SB- 2 and MW-11. Attempts to collect water samples using the simulprobe in boring MW-12 failed to obtain any samples. Soil samples were collected from borings MW-11, MW-12 and S13-2. Analytical results from the soil samples were all non-detect for the petroleum hydrocarbon constituents analyzed, except for 0.011 parts per billion (ppb)ethanol in the 110-foot sample from S13-2. Analytical results from the geoprobe grab water samples showed a few minor detections in borings WSP-1 and WSP-2. Analytical results from the simulprobe water samples also had a few minor detections,with a maximum of 100 ppb total petroleum hydrocarbons as diesel, 7.6 ppb benzene and 8.8 ppb 1,2-DCA in MW-11 at 70-feet bsg and 1.7 ppb 1,2-DCA in S6-2 at 90-feet bsg. The report concludes that information gathered from all site investigations to date indicate that the bulk of the on-site contamination is from the four underground storage tanks (UST's)previously located at the site. The report also concludes that the lateral and vertical extent of the contaminant plume appears to be fairly well defined. The report recommends continued groundwater monitoring and sampling for another four quarters, followed by a re-evaluation of the site conditions for further action. A Division of San Joaquin County Health Care Services