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• <br /> r <br /> GROUND ZERO ANALYSIS, INC. ^ <br /> 1714 Main Street l t <br /> Escalon, California 95320-1927 <br /> Telephone- (209) 838-9888 <br /> Facsimile. (209)838-9883 <br /> January 7, 2000 <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 Site Status Report, Fourth Quarter 1999 <br /> Knowles Property, 1140 W Hammer Lane, Stockton, California <br /> Dear Mr Knoll <br /> This report summarizes the fourth quarter 1999 activities at the subject site (Figure 1) Activities during <br /> the quarter included monitoring depth to water in all site wells, purging and sampling wells MW1, MW4, <br /> MW5, and MW8, and analyzing the samples for benzene, toluene, ethylbenzene, total xylenes (BTEX), and <br /> total petroleum hydrocarbons as gasoline (TPHg) <br /> GROUNDWATER MONITORING <br /> Groundwater monitoring was performed on November 8, 1999 The depth to groundwater beneath the site <br /> ranged from 34 58 feet below ground surface (bgs) in well MW3 to 36 61 feet bgs in well MW6 Overall <br /> groundwater elevations fell an average of 0 50 feet between August 10, 1999 and November 8, 1999 The <br /> water table beneath the site lies above the screened intervals for all wells except MWi, MW2 and MW3 <br /> Monitoring Weil construction details are summarized in Table I The groundwater flow at the time of <br /> measurement was generally southeast at gradient of 0 005 ft/ft A potentiometric surface map for <br /> November 8, 1999 is presented on Figure 2 Groundwater monitoring data are summarized in Table 2 <br /> GROUNDWATER SAMPLING AND ANALYSIS <br /> Monitoring wells MWi, MW4, MW5, and MW8 were sampled on November 8 and 9, 1999 A nummum <br /> of three well casing volumes of water was purged from each well prior to sampling Purged groundwater is <br /> currently stored on site in labeled drums approved by the Department of Transportation (DOT) pending <br /> disposal Copies of purge logs are included in Attachment A <br /> Groundwater samples were submitted to Argon Laboratories (ELAP #2359) for analysis of TPHg and <br /> BTEX utilizing EPA methods 8015 modified and 8020, respectively <br /> Groundwater samples collected from well MW 1 and MW5 contained petroleum hydrocarbon constituents <br /> exceeding their respective laboratory detection limits Most notably, well MW5 contained TPHg and <br /> benzene at 26,000 parts per billion (ppb) and 5,900 ppb, respectively Well MW 1 contained TPHg and <br /> knowles ham/reports/4gm1999 doc <br />