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GROUND ZERO ANALYSIS,INC. - 1714 Main Street Escalon,California 95320-1927 Telephone: (209)838-9888 Facsimile: (209)838-9883 October 19, 1999 Mr Harlin Knoll San Joaquin County Public Health Services Environmental Health Division 3 04 East Weber Avenue, Third Floor Stockton, CA 95202 Subject Site Status Report, Third Quarter 1999 Knowles Property, 1140 W Hammer Lane, Stockton, California Dear Mr Knoll This report summarizes the third quarter 1999 activities at the subject site (Figure 1) Activities during the quarter included monitoring depth to water in all site wells, purging and sampling wells MW1, MW2, MW3, MW4, MW5, and MW8, and analyzing the samples for benzene, toluene, ethylbenzene, total xylenes (BTEX), and total petroleum hydrocarbons as gasoline (TPHg) GROUNDWATER MONITORING Groundwater monitoring was performed on August 10, 1999 The depth to groundwater beneath the site ranged from 34 10 feet below ground surface (bgs) in well MW3 to 36 06 feet bgs in well MW6 Overall, groundwater elevations fell an average of 3 85 feet between May 11 and August 10, 1999 The water table beneath the site lies above the screened intervals for all wells except MW1, MW2 and MW3 Monitoring well construction details are summarized in Table 1 The groundwater flow direction at the time of measurement was generally to the southeast at a gradient of 0 007 ft/ft A potentiometnc surface map for August 10, 1999 is presented on Figure 2 Groundwater monitoring data are summarized in Table 2 GROUNDWATER SAMPLING AND ANALYSIS Monitonng wells MW1, MW2, MW3, MW4, MW5, and MW8 were sampled on August 10 and 11, 1999 A minimum of three well casing volumes of water was purged from each well prior to sampling The purged water from this event is currently stored on site in labeled drums approved by the Department of Transportation (DOT) pending disposal Copies of purge logs are included in Attachment A t knowles hamheporW3gm1999 d=