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i7 I <br /> A i f t <br /> _ f i <br /> GROUND ZERO ANALYSIS, INC. <br /> 14 <br /> 2291 W. March Lane, Suite 127D s 1 <br /> Stockton, California 95207 <br /> Telephone: (209Y952=34$-1 <br /> Facsimile: (209) 952-9891 <br /> September 22, 1997 <br /> Mr Harlin Knoll <br /> i San Joaquin County Public Health Services <br /> Environmental Health Division <br /> 304 East Weber Avenue, Third Floor <br /> Stockton, CA 95202 <br /> Subject Third Quarter 1997 Site Status Report <br /> Knowles Property <br /> 1140 W Hammer Lane, Stockton, California <br /> Dear Mr Knoll <br /> This letter report summarizes third quarter 1997 activities at the subject site (Figure 1) Activities <br /> during the quarter included monitoring depth to water 1n all site wells, purging and sampling wells <br /> MW 1, MW2, MW3, MW4, MWS, and MW8, and analyzing samples for total petroleum <br /> hydrocarbons as gasoline(TPHG), benzene, toluene, ethylbenzene, and total xylenes(BTEX) <br /> GROUNDWATER MONITORING <br /> Groundwater monitoring was performed on August 13, 1997 The depth to groundwater beneath the <br /> site ranged from 40 69 to 42 71 feet below grade Overall, groundwater elevations fell an average of <br /> 2 45 feet since May 9, 1997 The groundwater flow direction at the time of measurement was <br /> generally to the southeast with a hydraulic gradient of approximately 0 006 to 0 008 feet per foot <br /> (approximately 32-42 feet per m11e) A groundwater gradient map for August 13, 1997 is presented on <br /> Figure 2 Groundwater monitoring data are summarized in Table 1 <br /> GROUNDWATER SAMPLING AND ANALYSIS <br /> Monitoring wells MW1, MW2, MW3, MW4, MWS, and MW8 were purged and sampled on August <br /> 13 and 14, 1997 All purge water was contained on site in labeled drums approved by the Department <br /> of Transportation for storage of liquid waste Well purge logs are included in Attachment A <br /> Groundwater samples were submitted to Argon Laboratories (FLAP #1873) and analyzed for TPHG <br /> and BTEX using EPA methods 8015 modified and 8020, respectively <br /> 01 <br /> ground=\knowlca ham\3gm1997 doc <br />