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. GROUND ZERO ANALYSIS, INC. <br /> 1714 Maui Street <br /> Fscalon, Cahforme 95320 <br /> Telephone: (209) 838-9888 <br /> Facsumde. (209)838-9883 <br /> z� <br /> April 2, 1998 <br /> Mr Harlin Knoll <br /> San Joaquin County Public Health Services ' <br /> Environmental Health Division <br /> 304 East Weber Avenue, Third Floor <br /> Stockton, CA 95202 <br /> Subject First Quarter 1998 Site Status Report <br /> Knowles Property <br /> 1140 W Hammer Lane, Stockton, California <br /> Dear Mr Knoll <br /> . This letter report summarizes first quarter 1998 activities at the subject site (Figure 1) Activities <br /> during the quarter included monitoring depth to water in all site wells, purging and sampling wells <br /> MW 1, MW3, MW4, MW5, and MW8, and analyzing samples for total petroleum hydrocarbons as <br /> gasoline(TPHG), benzene,toluene, ethylbenzene,total xylenes(BTEX), and oxygenate compounds <br /> GROUNDWATER MONITORING <br /> Groundwater monitoring was performed on February 13, 1998 The depth to groundwater beneath <br /> the site ranged from 35 55 to 37 77 feet below grade Overall, groundwater elevations rose an average <br /> of 4 32 feet since November 6, 1997 The groundwater flow direction at the time of measurement was <br /> generally to the southeast A groundwater gradient map for February 13, 1998 is presented on Figure <br /> 2 Groundwater monitoring data are summarized in Table 1 <br /> GROUNDWATER SAMPLING AND ANALYSIS <br /> Monitoring wells MW 1, MW3, MW4, MW5, and MW8 were purged and sampled February 13, 1998 <br /> All purge water was contained on site m labeled drums approved by the Department of Transportation <br /> for storage of liquid waste Well purge logs are included in Attachment A Groundwater samples <br /> were submitted to Argon Laboratories (FLAP #1873) and analyzed for TPHG, BTEX, and oxygenate <br /> compounds using EPA methods 8015 modified, 8020, and 8260, respectively <br /> The groundwater sample collected from well MW5 contained elevated levels of petroleum <br /> hydrocarbons, BTEX and TPHG were detected at concentrations of 8,200 parts per billion (ppb), <br /> 5,800 ppb, 890 ppb, 9,300 ppb, and 69,000 ppb, respectively MW1 contained BTEX and TPHG <br /> groundzelknowles hamVeporisl l gm 1998 doc <br />