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I Field Report Groundwater Sampling for MW-4 Grantline Plaza Tracy. California i. On July 10 and 16, 1991, ROY F. WESTON, INC. (WESTON) sampled groundwater from } the newly installed monitoring well MWA at the Grantline Plaza site at 350 West Grantline E' Road in Tracy, California. The field work was:conducted to evaluate if petroleum compounds were present in the groundwater downgradient from the former UST location and if migration had occurred along storm drain piping running north-south adjacent to the " restaurant building. On July 10, 1991, an initial water sample was collected from MW-4 with a follow-up confirmation sample;taken on July 16, 1991. The samples collected were identified as MW-4 for both samplings. Prior to purging the well, measurements of total well depth and depth to water were taken. From these measurements, the standing water i volume within the well casing was € calculated. i`At this point a clear teflon bailer was lowered into and retrieved from the well. No floating product or petroleum odors were noted. A submersible pump was then used to purge the four inch well of at least three well volumes. Physical parameters of pH, .r electrical conductivity, and temperature were collected from the purge water. This information'is presented in Table A-2. A clear teflon 'bailer was then used to collect the water samples. TABLE A-2 Field Water Quality Measurements End of Purge Values k well/sample Date pH Temperature Conductivity i (°F) (umhos) f, MW-4 7110/91 8.2 72.2 2810 MW-4' 7116191 7,4 69.4 2660 The bailer used to sample each well was attached to new thin nylon line and lowered into the well byhand. The bailer was filled and brought to the surface. The water in the } bailer was carefully poured into laboratory prepared 40 milliliter glass bottles (VOAs) and i A - 6 �� _. -