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WA A ERWTCO <br /> IN <br /> CEOCMEMICAL•GEOTECFINICAL•ENVIRONMENTAL <br /> November 16, 1990 <br /> Ms. Diane Hinson NOV 21 <br /> San Joaquin County V i HEALTH <br /> ;LLATf{ <br /> Department of Environmental Health <br /> P.A. Box 2009 PERi'.i"USL ivi 1.S <br /> Stockton, Ca 95201 <br /> Re: 1990 Third Quarter Monitoring Report, 8181 East <br /> Eleventh Street, Genstar Western Stone, Tracy, CA <br /> I } <br /> Dear Ms. Hinson: <br /> s <br /> This letter is to report the groundwater monitoring activities <br /> during the third quarter of 1990 at the above referenced este and <br /> also address the issues presented in your letter of October 15, ' <br /> 1990 (Figure 1). <br /> z Activities during the quarter have included the purging of the <br /> ^ wells, sampling for benzene, toluene, ethylbenzene, xylenes <br /> (BTEX) and total <br /> ' petroleum hydrocarbons as diesel (TPHD), and <br /> monitoring of groundwater. <br /> Groundwater monitoring was conducted on October 80, 1990. Depth <br /> to water was measured for each well (Table 1) and a groundwater <br /> gradient map was created using a kriging program (Figure 1), The <br /> water elevation is approximately three feet lower than when the 4 <br /> elevation was measured in October of 1989. Groundwater flows at <br /> approximately 0.004 ft/ft in a northwesterly direction. <br /> Groundwater samples were collected, and analyzed for BTEX and <br /> TPHD using EPA 8015/8020 methodology (Table 2). Samples are <br /> collected after all parameters for pH, conductivity and <br /> temperature have stabilized. No concentrations of BTEX and TPHD <br /> were detected above method detection limits in any of the wells. <br /> . <br /> Laboratory reports, development purge logs, and chain-of-custody <br /> are resented in y <br /> p Attachment 1. <br /> ADDENDUM TO FEAR OF JUNE 22, 1990 <br /> Section 2.8 <br /> In response to your letter of October 15, 1990 we have conducted a <br /> well search for private, municipal and domestic wells within a <br /> one-mile radius of the site. Well locations <br /> Figure 2. are presented an <br /> 1710 MAIN STREET • ESCALON,CA 95320 • (209)838-3507 I <br /> FRESNO,CA(209)222-3495 • RENO.NV(702) 788-6830 <br />