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1 <br /> E11[�y't® <br />' ENSR International <br /> 10411 Old Placerville Road <br /> U4 Suite 210 <br /> �'VEJ)amento. <br /> CA 95827-2508 <br /> July 28, 2005 iI-� ' (916)362-7100 <br /> 2b�5 FAX (916)362-8100 <br /> www ensrcom <br /> Mr Jeff Wong yVIR�,viv,�s i� 1 s�ALTH <br /> San Joaquin County p£RM'T]S£fV� � <br />' Environmental Health Department <br /> 304 E Weber Avenue, Third Floor <br /> Stockton, California 95202 <br /> RE Quarterly Groundwater Monitoring Results Report, Second Quarter 2005 <br />' Stockton Scavenger Association Facility <br /> 1240 Navy Drive, Stockton, California <br />' Dear Mr Wong <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 second quarter 2005 The work <br /> was performed in accordance with the field methods and procedures included in Attachment A <br /> Prior to this groundwater monitoring event, a storm water drain had been plugged on site and <br /> the area around the flush-mounted monitoring wells had been flooded for a sustained period of <br /> time <br /> Groundwater Level Measurements <br /> Depths to groundwater were measured in monitoring wells MW-1 through MW-4 on June 21, 2005 <br /> These measurements are presented in Table 1, and were used to construct a groundwater <br /> elevation contour map included as Figure 3 MW-2 data was not included in the contour map due <br />' to an anomalous groundwater elevation The groundwater in the vicinity of the former excavation <br /> pit (MW-2) may be higher in elevation than areas of undisturbed native soil In general, <br /> groundwater appears to have been flowing south southeast with a gradient of 0 001 feet per foot <br />' <br /> (ft/ft) on June 21, 2005 This is comparable with historical groundwater gradients Copies of the <br /> groundwater sampling information sheets are included in Attachment B A summary of <br /> groundwater elevations measured to date is presented in Table 1 <br /> Groundwater Sampling and Analytical Results <br /> Groundwater samples were collected from monitoring wells MW-1 through MW-4 on <br /> June 21, 2005 Groundwater samples were submitted to California Laboratory Services (CLS) in <br /> Rancho Cordova, California, under chain of custody protocols CLS analyzed the samples for <br /> benzene, toluene, ethylbenzene and total xylenes (BTEX) by EPA Method 8021, for total <br /> Celebrating 35 Years of Excellence in Environmental Services <br />