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5 � V <br /> Rb <br /> GROUND ZERO ANALYSIS INC. � <br /> 1714 Main Streetd <br /> � O <br /> Escalon,California 95320-1927 <br /> Telephone (209)838-9888 <br /> Facsimile (209)838-9883 <br /> January 10, 2006 <br /> Mr Harlin Knoll <br /> San Joaquin County Environmental Health Department <br /> 304 East Weber Avenue, Third Floor <br /> Stockton, CA 95202 <br /> Subject Fourth Quarter 2005 Groundwater Monitoring Report <br /> 7835 Thornton Road, Stockton, CA(APN 4077-490-27) <br /> Dear Mr Knoll <br /> This report summarizes activities at the subject site during the fourth quarter 2005 The site location is <br /> presented on Figure l Activities conducted during the reporting period included monitoring depth to <br /> water in site wells, purging and sampling well MW5, and analyzing groundwater sample for benzene, <br /> toluene, ethylbenzene, total xylenes (BTEX), and total petroleum hydrocarbons as gasoline (TPHg) <br /> GROUNDWATER MONITORING AND SAMPLING <br /> An experienced Ground Zero technician measured the depth to groundwater in wells MW 1, MW2, MW3, <br /> MW4, MW5, and MW9 on November 22, 2005 The depth to groundwater beneath the site ranged from <br /> 37 18 feet below the top of the well casing (btoc) in well MW3 to 38 81 feet btoc in well MW2 <br /> Groundwater elevations in site wells rose an average of 0 77 feet between August 23, 2005 and November <br /> 22, 2005 The water table beneath the site lies above the screened intervals in wells MW4 and MW5 <br /> Groundwater flow was generally toward the east/northeast with an average gradient of 0 0023 feet per foot <br /> (approximately 12 feet per mile) A potentiometric surface map for November 22, 2005 Is presented on <br /> Figure 2 Monitoring well construction details are summarized in Table 1 Groundwater monitoring data <br /> is summarized in Table 2 <br /> A Ground Zero technician purged at least three well casing volumes of groundwater from monitoring well <br /> MW5 on November 22, 2005 Physical parameters (temperature, specific conductance, and pH) were <br /> measured and recorded during the purging process Groundwater samples were collected using a dedicated <br /> disposable bailer after physical parameters stabilized and the water level recovered to the pre-purged <br /> Ievels The samples were decanted into 40-m1 glass VLals preserved with a hydrochloric acid solution The <br /> samples were subsequently placed in an ice chest refrigerated to a temperature of approximately 4°C <br /> The samples were transported to Argon Laboratories (ELAP #2359) under chain of custody protocol and <br /> analyzed for TPHg and BTEX utilizing EPA methods 8015B and 802113, respectively Purged <br /> groundwater was contained in a labeled 55-gallon drum pending disposal Copies of field purge logs and <br /> water level measurements are included in Attachment A <br /> G IGROUNDZEIKNOWLES HAMIREPORTSIQMR1200514QM2005 doe <br />