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1 <br /> PUBLIC HtALTH SERVICtS <br /> SAN JOAQUIN COUNTY <br /> ENVIRONMENTAL HEALTH DIVISION <br /> Karen Furst, M.D., M.P.H., Health Officer �. _. <br /> 304 East Weber Avenue, Third Floor - Stockton, CA 95202 <br /> 209/468-3420 <br /> BUTCH SCHMIDT .JUL 2 U 2000 <br /> STOCKTON UNIFIED SCHOOL DISTRICT (SUSD) <br /> 1932 EL PINAL DRIVE <br /> STOCKTON CA 95205 <br /> RE: FRANKLIN HIGH SCHOOL SITE CODE: 1578 <br /> 300 NORTH GERTRUDE AVENUE <br /> STOCKTON CA 95206 <br /> San Joaquin County Public Health Services,Environmental Health Division (PHS/EHD) <br /> has reviewed Sexnd C w?wr 2000 GnxazliruterMaitori Report for the above-referenced site <br /> dated June 27,2000,prepared by ATC Associates,Inc (ATC). A monitoring well (MW 1) <br /> was installed in February 1999 near the center of the former tank excavation. Analytical <br /> results of the water sample collected from MW-1 on June 5,2000,was 5.40 parts per billion <br /> (ppb) of Methyl tert-Butyl Ether(lvME),falling from a high of 51.4 ppb of MTBE in <br /> February 1999. Depth to Groundwater on June 5,2000,was 52.33 feet below surface grade <br /> (bsg),rising from 54.84 feet bsg in February 1999 and 53.88 feet bsg in March 2000. <br /> Analytical results were all non-detect at detection limits of 0.500 ppb for aromatic <br /> hydrocarbons as Benzene,Toluene,Ethyl-benzene,and Xylenes (BTEX collectively),and 50 <br /> ppb of Total Petroleum Hydrocarbon as gasoline ('IPH g). Tert-Butyl Alcohol(TBA) was <br /> non-detect at a detection limit of 200 ppb. <br /> In a letter dated July 1, 1999,PHS/EHD commented that based on field observation during <br /> the installation of MW-1 in February 1999 and analytical results as reported in Surminy <br /> Report cf A ddzdcntl Suksurfuce Imestigzmw dated June 1, 1999 prepared by ATC Associates,Inc <br /> (ATC),the hydrocarbon petroleum contamination in the soil seemed to be limited to <br /> approximately 25 feet bsg and above,but MTBE has infiltrated at least as deep as 55 feet bsg <br /> where the water table was at the time. At present the lateral and vertical extent of the <br /> contamination in both soil and groundwater remain undefined. In the year since the <br /> installation of MW 1,the concentration of MTBE in groundwater has dropped by an order <br /> of magnitude. According to MW 1 boring log,a layer of silty sand from 41 feet bsg to 52 <br /> feet bsg is followed by layer of clayey sand from 51.5 feet bsg to 56 feet bsg,which is <br /> followed by more silty sand. The geology below 61.5 feet bsg is unknown. Given the highly <br /> mobile nature of MTBE and the porous lithological conditions identified so far in the upper <br /> aquifer,additional information is required to define the three-dimensional extent of the <br /> contamination,calculate the mass volume of the contaminants in both soil and groundwater, <br /> and evaluate the continuing migratory potential of the MTBE plume to a deeper aquifer <br /> before cleanup alternatives or closure of the site can be considered. <br /> A Division of San Joaquin County Health Care Services <br />