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GROUND ZERO ANALYSIS, INC. <br /> . 1714 Main Street <br /> Escalan, California 95320-1927 <br /> Telephone (209)838-9888 <br /> Facsimile (209)838-9883 <br /> February 21, 2002 <br /> Ms Lori Duncan <br /> San Joaquin County Environmental Health Department <br /> 304 East Weber Avenue, Third Floor <br /> Stockton, CA 95202 <br /> Subject Quarterly Groundwater Monitoring Report,4"'Quarter 2001 <br /> 640 N El Dorado Street, Stockton, California <br /> Dear Ms Duncan <br /> Tlus letter report presents the results of the fourth quarter 2001 groundwater monitoring and sampling <br /> activities at the subject site(Figure 1) <br /> SITE ACTP TI'IES <br /> iActivities at the site included monitoring water level elevations,purging and sampling groundwater from site <br /> wells, removing free product from well MW3, and analyzing groundwater samples for total petroleum <br /> hydrocarbons as gasoline (TPHg), total petroleum hydrocarbons as diesel (TPHd), total recoverable <br /> petroleum hydrocarbons (TRPH), benzene, toluene, ethylbenzene, total xylenes (BTEX), oxygenated <br /> gasoline additives, volatile organic compounds (VOCs), and dissolved lead <br /> FIELD WORK <br /> Groundwater Monitoring <br /> Monitoring wells MW1 through MW4 were monitored and wells MWl, MW2 and MW4 sampled on <br /> December 12, 2001 No samples were collected from well MW3 due to the presence of free product The <br /> depth to water in wells MW1, MW2, and MW4 were monitored using an electronic water level indicator <br /> The depth to water and depth to product in well MW3 were measured using an electronic water- <br /> hydrocarbon interface probe <br /> Groundwater elevations were calculated by subtracting the measured depth to groundwater in each well <br /> from the respective wellhead elevation The depth to groundwater in the wells on December 12, 2001 <br /> ranged from 22 33 to 23 98 feet below ground surface (bgs) Groundwater flow was in a northeast direction <br /> with an average gradient of approximately 0 003 (or approximately 16 feet per mile) A potentiometnc <br /> surface map generated using the December 12, 2001 monitoring data is shown on Figure 2 Groundwater <br /> momtonng data are summarized in Table 1 Monitoring data sheets are included in Attachment A <br /> 11GZA_FS\,SYSU11Data1GROUNDZEIGABBARD\reporls14QM2001 doc <br />