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SERVICEPUBLIC'"REALTHG <br /> SAN JOAQUIN COUNTY p <br /> ENVIRONMENTAL HEALTH DIVISION <br /> Ernest M. Fujimoto, M.D., M.P.H., Acting Health Officer <br /> �%FOR <br /> 445 N. San Joaquin Street • P.O. Box 388 • Stockton, CA 95201-0388 <br /> (209) 468-3420 <br /> C(DPY <br /> EUGENE M KULESZA <br /> RIVERSIDE CEMENT COMPANY ;� <br /> P O BOX 56040 i�PDR 0 4 199-4 <br /> RIVERSIDE CA 92517 <br /> RE: Riverside Cement Co. SITE CODE: 2588 <br /> 2825 W. Washington <br /> Stockton, CA <br /> San Joaquin County Public Health Services, Environmental Health <br /> Division (PHS/EHD) has reviewed your January 21, 1994 letter. This <br /> response should clarify previous site information obtained and <br /> provide answers to the questions in your letter. <br /> On April 6, 1993 further excavation of the former underground <br /> storage tank (UST) area was conducted and contaminated soil was <br /> removed. Five sidewall soil samples above groundwater were <br /> collected and the results of their analysis confirmed that <br /> contaminated soil above groundwater had been removed. <br /> Since there was water in the excavation a bottom soil sample was <br /> not collected. A sample of the water in the excavation was <br /> collected and analyzed. Contaminants were not detected in that <br /> water sample. The contaminants being investigated volatilize into <br /> the air upon exposure to it. Therefore, obtaining a water sample <br /> from an aerated excavation is not considered representative of the <br /> groundwater beneath the site which has not been exposed to air. <br /> The only way to obtain a representative sample of the groundwater <br /> beneath the site is to install a monitoring well within 10 feet of <br /> the former tank location in a downgradient position and obtain a <br /> groundwater sample from that well following established protocol. <br /> Since other sites adjacent to this site are conducting groundwater <br /> investigations, PHS/EHD is aware that the gradient in this area is <br /> divergent. Therefore, PHS/EHD will allow the installation of one <br /> monitoring well in the area of the former UST location. Since no <br /> soil samples were collected from the bottom of the excavation, a <br /> soil sample should be collected at 10 feet below grade to verify <br /> the soil beneath groundwater is clean. <br /> Since the former underground storage tank contained gasoline, the <br /> soil and groundwater samples are to be analyzed for benzene, <br /> toluene, ethylbenzene, xylene, and total petroleum hydrocarbons as <br /> A Division of San Joaquin County Health Care Services <br />