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FIELD REPORT <br /> GROUND WATER SAMPLING <br /> ' EAST BAY MUNICIPAL UTILITY DISTRICT <br /> STOCKTON CENTER, STOCKTON, CALIFORNIA <br /> ' On March 2, 1993, ROY F WESTON, INC (WESTON®) conducted a groundwater sampling <br /> event at the East Bay Municipal Utility District (EBMUD) Stockton Center facility in Stockton, <br /> California Water samples were collected from four of the seven monitor wells (MW-1, MW-2, <br /> MW-5 and MW-7) located on the site The field work was performed in an ongoing effort to <br /> characterize the presence of petroleum compounds in groundwater <br /> Groundwater samples were identified with the number of the well from which they were <br /> collected The monitor well sampling order was based on the previous analytical results and was <br /> ' arranged from lowest to highest concentrations as follows <br /> MW-7 <br /> ' MW-5 <br /> MW-2 <br /> MW-I <br /> MW-8 (duplicate of MW-1) <br /> Prior to purging each well, measurements of total well depth and depth to water were taken from <br /> all seven wells onsite The top of each PVC well casing has been previously surveyed to <br /> establish the elevations of those wells relative to an arbitrary datum of 100 feet Using the well <br /> casing elevations and the measured depths to water, the relative groundwater elevation at each <br /> ' well was calculated From the water level depths and the know total well depths, the standing <br /> water volume within the well casing of the four wells to be sampled was also calculated A <br /> teflon bailer was then used to purge at least three well volumes from each 2-inch well to be <br /> ' sampled of at least three well volumes Physical parameters of pH, electrical conductivity and <br /> temperature were measured at the conclusion of the well purge The groundwater physical <br /> parameters are presented in Table A-I A clear teflon bailer was then used to collect the water <br /> ' samples <br /> TABLE A-1 <br /> ' Groundwater Physical Parameters <br /> End of Purge Values <br /> ' Welt/Sample pH Temperature(F) Conductivity <br /> (umbos) <br /> ' MW-1 7 1 650 1069 <br /> MW-2 65 67 3 2320 <br /> MW-5 7 8 622 2090 <br /> MW-7 75 654 1802 <br /> ' SI 10RFfs\mmt4lISrWP A — 1 04WM <br />