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Vj a F A 5 S 0 3.2 Hydrogeolozy Water level measurement r s were collected during dissipation tests from the uppermost water bearing zone in borings CPT-2 through CPT-5, from June 16 through 19, 2003 The water level at CPT-2 was measured to be approximately 64 feet bgs The water level at CPT-3 was measured to be approximately 66 75 feet bgs The water level at CPT-4 was measured to be ' approximately 65 22 feet bgs The water level at CPT-5 was measured to be approximately 62 30 feet bgs On July 21, 2003, water levels were collected prior to the start of the pump test from wells MW1, MW3, MW6, MW7, ASI, AS1d, PZ113(d), DW, and PZ1A(d) The water level data from the monitoring wells were used to develop the groundwater elevation contour map (Figure 3) Assuming that horizontal isotropic conditions prevail, groundwater in the uppermost aquifer beneath the site flowed towards the southeast The average hydraulic gradient on July 21, 2003 was calculated to be 0 01 ft/ft or approximately 55 ft/mile A summary of groundwater ' monitoring data is presented in Table 3 4.0 GROUNDWATER PUMP TEST A groundwater pump test was recommended by ATC in its Workplan for Additional Subsurface Investigation at Pacific Coast Recreation, 3755 Munford Avenue, Stockton, California, dated ' February 13, 2003 and approved in correspondence from SJEHD, dated April 10, 2003 The purpose of the pump test was to investigate the vertical connectivity between shallow and deep aquifers and to assess the effects of pumping on vertical plume migration in the vicinity of the ' former USTs The scope of work for the pump tgst consisted of the extraction of groundwater from the domestic well for approximatelyAours, and monitoring the changes in groundwater levels in observation points AS 1, AS1(d), PZ1a(d), PZlb(d), MW 1, MW3, MW6, and MW7 ' 4_1 Groundwater Pump Test Methods and Procedures The groundwater pump test was conducted on July 21, 2003 over an approximate 5-hour period by extracting groundwater at a generally constant rate from the domestic well on site ' The domestic well is typically operated on a periodic basis during the work week (Monday through Friday) with an approximate groundwater extraction rate of 700 gallons per day or 0 5 gallons per minute On Friday July 18, 2003 ATC installed pressure-sensitive transducers in wells AS 1, MW3, and MW6 On July 21, 2003 before the start of the pump test, depth to water levels were measured to determine baseline groundwater levels and the magnitude of background fluctuations in water levels caused by barometric, tidal, or other influences S\Enviromenta11163931REPORTSIcptpumpreport doe 5