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s <br /> • GROUND ZERO ANALYSIS, INC. T ,� r; Z41 �{ <br /> 2291 W. March Lane, Suite 127D <br /> Stockton, California 952078 <br /> Telephone: (209) 952-3481 <br /> Facsimile. (209) 952-9891 <br /> April 18, 1997 <br /> Mr Harlin Knoll <br /> San Joaquin County Public Health Services <br /> Environmental Health Division <br /> P O Box 388 <br /> Stockton, CA 95201-0388 <br /> Subject First Quarter 1997 Site Status Report, Knowles Property, 1140 W Hammer Lane, <br /> Stockton, California <br /> Dear Mr Knoll: <br /> This letter report summarizes first quarter 1997 activities at the subject site (Figure 1) Activities <br /> during the quarter included monitoring depth to water in all wells, purging and sampling wells <br /> MWI, MW3, MW4, MWS, and MW8, and analyzing samples for total petroleum hydrocarbons as <br /> gasoline (TPHg), benzene, toluene, ethylbenzene, and total xylenes (BTEX) <br /> GROUNDWATER MONITORING <br /> Groundwater monitoring was performed on February 21, 1997 The depth to groundwater beneath <br /> the site ranged from 38 77 to 40 90 feet below grade Overall, groundwater elevations rose an <br /> average of 2 30 feet since December 30, 1996 The groundwater flow direction at the time of <br /> measurement was generally to the southeast with a hydraulic gradient of approximately 0 007 feet <br /> per foot (37 feet per mile) A groundwater gradient map for February 21, 1997 is presented on <br /> Figure 2 Groundwater monitoring data are summarized in Table 1 <br /> GROUNDWATER SAMPLING AND ANALYSIS <br /> Monitoring wells MW1, MW3, MW4, MWS, and MW8 were purged and sampled February 21, <br /> 1997 All purge water was contained on site in labeled drums approved by the Department of <br /> Transportation Well purge logs are included in Attachment A Groundwater samples were <br /> submitted to Argon Laboratories (FLAP #1873) and analyzed for TPHg and BTEX using EPA <br /> methods 8015 modified and 8020, respectively <br /> groundzelknowles hnmAgm1996 <br />