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1 <br />' ENSR International <br /> . 10411 Old Placerville Road <br /> Suite 210 <br /> ECEIV�� Sacramento,CA 95827-2508 <br /> (916)362-7100 <br /> May 4, 2005 <br /> FAX (916)362-8100 <br /> MAY 0 9 2005 www ensr com <br />' IMRONMEW FIWM <br /> Mr .teff Wong PEIm"SO&M <br />' San Joaquin County <br /> Environmental Health Department <br /> 304 E Weber Avenue, Third Floor <br />' Stockton, California 95202 <br />' RE: Quarterly Groundwater Monitoring Results Report, First Quarter 2005 <br /> Stockton Scavenger Association Facility <br /> 1240 Navy Drive, Stockton, California <br /> Dear Ms Dietz <br /> ENSR Corporation (ENSR) has been authorized by Norcal Waste Systems Inc (Norcal Waste) <br /> to perform quarterly groundwater monitoring at the site located at 1240 Navy Drive, Stockton, <br /> California (Figure 1) The locations of former and current site features are illustrated on <br /> • Figure 2 Quarterly groundwater monitoring is intended to evaluate the distribution of petroleum <br /> hydrocarbon constituents in groundwater beneath the site This report summarizes analytical <br /> results for groundwater samples collected at the site during the first quarter 2005 The work <br /> was performed in accordance with the field methods and procedures included in Attachment A <br /> Groundwater Level Measurements <br /> Depths to groundwater were measured in monitoring wells MW-1 through MW-4 on <br /> February 23, 2005 These measurements are presented in Table 1, and were used to construct a <br /> groundwater elevation contour map included as Figure 3 MW-2 data was not included in the <br /> contour map due to an anomalous groundwater elevation The groundwater in the vicinity of the <br /> former excavation pit (MW-2) may be higher in elevation than areas of undisturbed native soil In <br /> general, groundwater appears to have been flowing southeast with a gradient of 0 001 feet per <br /> foot (Rift) on February 23, 2005 Copies of the groundwater sampling information sheets are <br /> Included in Attachment B A summary of groundwater elevations measured to date is presented <br /> in Table 1 <br /> Groundwater Sampling and Analytical Results <br /> Groundwater samples were collected from monitoring wells MW-1 through MW-4 on <br /> February 23, 2005 Groundwater samples were submitted to California Laboratory Services <br /> (CLS) in Rancho Cordova, California, under chain of custody protocol CLS analyzed the samples <br /> for benzene, toluene, ethylbenzene and total xylenes (BTEX) by EPA Method 8021, for total <br /> petroleum hydrocarbons as gasoline (TPHg) and total petroleum hydrocarbons as diesel (TPHd) <br /> . by EPA Method 8015M, and for methyl tertiary butyl ether (MTBE) by EPA Method 8260B <br /> J\Pmjects10502710311workingT5027-031-Ist Qtr 05 QMR doc <br /> ICelebrating 35 Years of Excellence in Environmental Services <br />