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' FIELD REPORT <br /> 1 GROUND WATER SAMPLING <br /> EAST BAY MUNICIPAL UTILITY DISTRICT <br /> STOCKTON CENTER, STOCKTON, CALIFORNIA <br /> ' On May 28, 1993, ROY F WESTON, INC (WESTON(D) conducted groundwater sampling at <br /> 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 /> I <br /> MW-7 <br /> ' MW-5 <br /> MW-2 <br /> MW-1 <br /> MW-9 (equipment decontamination sample after collection <br /> of sample from 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 known 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 diameter well <br /> Physical parameters of pH, electrical conductivity and temperature were measured at the <br /> conclusion of the well purge The groundwater physical parameters are presented in Table A-1 <br /> ' A clear teflon bailer was then used to collect the water samples <br /> TABLE A-1 <br /> Groundwater Physical Parameters <br /> End of Purge Values <br /> ' Well/Sample pH Temperature(F) Conductivity <br /> (umhos) <br /> ' MW-1 7 4 67 3 1178 <br /> MW-2 77 66 8 1457 <br /> MW-5 79 659 2600 <br /> MW-7 77 662 1735 <br /> ' smK RFwEBMUD-NO WP A - l 07114193 <br />