SITE INFORMATION AND CORRESPONDENCE

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PUBLIC r1EALTH SERVICES aPA�I SAN JOAQUIN COUNTY ENVIRONMENTAL HEALTH DIVISION Karen Furst, M.D., M.P.H., Health Officer c�,• �r 304 East Weber Avenue,Third Floor • Stockton, CA 95202 2091468-3420 FILE COPY DOUG STIDHAM CITY OF ESCALON APR 2 0 1999 P O SOX 248 ESCALON CA 95320 RE- South County Food and Fuel, ARCO SITE CODE: 1487 1305 Escalon Ave. Escalon CA 95320 San Joaquin County Public Health Services, Environmental Health Division (PHSIEHD) has reviewed the "Work Plan, Soil & Groundwater Investigation, Groundwater Monitoring & Feasibility Study" dated March 31, 1999,that was prepared by Geological Technics Inc. (GTI) for the above referenced site, and has the following comments. The work plan proposes the installation of six wells. Three monitoring wells (MW-1, MW-2 and MW-3) will be installed to encounter first ground water, screened from 55-75 feet below surface grade (bsg). One deep monitoring well (MW-101) will be installed and discretely screened from 102.5-105 feet bsg. And two soil vapor extraction wells will be installed, one screened from 40-55 feet bsg (VEW-1), and the other screened from 12-27 feet bsg (VEW-2). All of the wells will be built with piping connecting them to the soil vapor extraction and treatment equipment, which will be located in a secured area on the north side of the existing on-site building. The piping will be located in trenches underground, and the wells will be covered with temporary steel boxes to protect them while area road construction continues. In a conversation between GTI and PHSIEHD it was understood that the piping from each monitoring well would not actually be connected to any type of manifold system until such time as it is decided that soil vapor extraction will be the remediation method used at this site. For the pilot test, the monitoring wells will be used to test for radius of influence. The piping from each well will be capped off and individually gauged during the test. The work plan proposes that the two vapor extraction wells be located in what is the current sidewalk on the eastern side of the property, and that MW-3 be located off site. These locations will place the wells in the future roadway. PHSIEHD understands the reason for this is to have the wells, and more importantly the piping lines, in place before the new road is built. This will hopefully avoid the necessity of tearing up the new road. While this placement will also provide information on the eastern lateral extent of the contaminant plume, PHSIEHD is concerned that the vapor extraction wells will be approximately 30 feet from the area which had the highest documented levels of soil contamination. A Division of San Joaquin Counry Health Care Services