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First Quarter 2002 Monitonng and Sampling Report 2 <br /> 7-Eleven, Inc Store No 20632,4627 DaVinci Drive,Stockton CA April 1 2002 <br /> replacement well for former well MW-4 (abandoned during tank removal), and a vertical delineation soli <br />' boring <br /> The scope of work was revised in the field (April 2002) due to access restrictions and addition of feasibility <br />' testing wells as approved by the SJCPHS The revised scope of work will be detailed in the report of <br /> findings <br />' Geology/Hydrogeology <br /> t The relatively flat site is located at an elevation of approximately 2 feet above mean sea level The site is <br /> underlain by Quaternary alluvial deposits Materials encountered during previous drilling at the site <br /> generally consisted of alluvial silts and clays to maximum exploratory drilling depths ranging from 4 5 to <br />' 21 5 feet below ground surface (bgs) <br /> Historically, groundwater has been encountered at depths ranging from 10 to 15 feet below grade Depth <br /> to water at the subject site for the current quarter ranged from 4 13 to 5 32 feet below grade Historical <br /> groundwater flow has been to the south-southwest The piezometric surface for the quarter Is shown on <br /> Figure 2 <br /> Sensitive Receptors <br /> Previous reports Indicate that there are no public water supply wells located within one mile downgradient <br /> of the site <br />' Groundwater Monitoring Data <br /> Before monitoring, the well caps were opened to allow the water In each well to stabilize to atmospheric <br /> pressure The DTW was measured to the nearest 0 01 foot from the top of the well casing using an <br /> ' interface probe <br /> A potentiometrlc surface map prepared using the quarterly groundwater elevation data is shown on <br /> Attachment 1, Figure 2 Based on the groundwater elevation data, groundwater flow Is toward the <br /> southwest at an approximate hydraulic gradient of less than 0 001 foot per foot Groundwater monitoring <br /> results for the quarter and historical monitoring results are presented in Tables 1 and 2, respectively <br /> ' (Attachment 2) Field data sheets are Included in Attachment 3 <br /> 1 <br /> 1 <br /> 20632Q21 QMR DOC <br /> J <br />