SITE INFORMATION AND CORRESPONDENCE

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PUBLIC HEALTH SERVICES SAN JOAQUIN COUNTY ' ENVIRONMENTAL HEALTH DIVISION Karen Furst, M.D., M.P.H., Health Officer 304 East Weber Avenue,Third Floor• Stockton, CA 95202 209/468-3420 FILE COPY MIKE KARVELOT QUIK STOP MARKETS INC SEP 151998 4567 ENTERPRISE ST FREMONT CA 94538-7605 RE: QUIK STOP MARKET#121 SITE CODE: 1430 1196 W. LOUISE AVE. MANTECA, CA 95336 San Joaquin County Public Health Services/Environmental Health Division (PHS/EHD) has reviewed the"Addendum to Work Plan for Soil and Groundwater Investigation"which was prepared by Compliance and Closure, Inc. for the above referenced site and has the following comments for your consideration and action. As a preliminary investigation the proposed locations of the geoprobe soil borings will be satisfactory with the following modifications: The boring proposed south of the new tank farm should be moved to the northwest so that it is located to the east of the new tank farm and closer to the corner of the former tank pit. The boring proposed in the northeast comer of the property should be moved south so that it is located within twenty feet of the dispenser island. The first soil boring will be done within five feet of the location of sample S-5 (collected at the time of the tank removals). This boring will be done as a continuous core, and needs to be advanced to depth such that field observations and PID readings indicate that vertical definition may have been made. Please note that it may be necessary to advance this boring to greater than 30 feet in depth. The information obtained from this boring will direct the depth to which the subsequent borings will need to be advanced. In addition, at least one more boring shall be drilled as a continuous core. This boring needs to be outside of the former tank pit area, PHS/EHD recommends the boring to the east of the new tank farm. Groundwater samples will be collected for analysis from each boring at the termination of the borehole. In addition, soil samples will be collected from each borehole at 5 foot intervals, beginning at five feet below surface grade (bsg), with the exception of the boring in the former tank pit where sampling can begin below the backfill. Determination of which soil samples will be submitted for analysis shall be made after field observations. Please note that it is likely that more than eight soil samples will need to undergo analysis in order to make a thorough site characterization. As noted in the work plan all soil and groundwater samples will be analyzed for total petroleum hydrocarbons as gasoline(TPHg) by method 8015m; benzene, toluene, ethylbenzene and xylene(BTEX) by method 8020, and oxygenates by method 8260. The purpose of doing investigative field work is to obtain as much information as possible about the extent and intensity of the hydrocarbon contamination present at the site. The information obtained from the geoprobe borings should be able to direct the need for future work, such as the proper placement of monitoring wells and the determination of the mass of contamination present. A Division of San Joaquin County Health Care Services