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Canepa's Car Wash 6230 Pacific Avenue, Stockton, California January 31, 1995 Groundwater Pump Test Page: 2 stations And MW4, a two-inch (2") morutonng well, was installed in the alley north of the ' car wash building in the estimated down gradient direction Written permission to drill and install a monitoring well was obtained from the manager of the Kentucky Fried Chicken I The vertical and lateral limits of contamination were not sufficiently defined with these four wells (NM-1, 2, 3 & 4) WHF proposed four additional "step-out" monitoring wells to fully characterize the groundwater contamination plume San Joaquin County Environmental ' Health Division granted approval on January 19, 1994 Between March 9 and 11, 1994, WHF, Inc installed four (4) two-inch (2") groundwater monitoring wells MW-5, 6, 7 & 8 (Figure 2) After MW-5, 6, 7 & 8 were installed, all wells were surveyed, measured and ' sampled Another gradient was calculated from the March 30, 1994 data The resulting map shows a mound in the water table that can only be caused by recharge (leakage) into the groundwater in the vicinity of MW-1 & 2 The previous gradient maps of 11/1, 1217 and ' 12/29/93 did not have sufficient data to reveal the whole mound There are three probable sources of recharge 1 ) the car wash recycles wash water through a ' pit system under the building, 2 ) a leaking or broken sewer line that crosses the area, and 3 ) a leaking water supply line, although this should have become evident at the surface by now An MBAS (Methylene Blue Active Substances) test was conducted in July, 1994 to detect soap/detergents The results were negative It would appear that the local gradient is to the east-northeast, because of the steep gradient on the west side of the mound and the flatter gradients on the east side This correlates with data from the San Joaquin County Flood ' Control and Water Conservation District map showing Lines OfEqual Elevation Of Water In Wells, Spring.1983 In order to design a groundwater remediation system, it will be necessary to know the volume and source of the recharge WHF recommended conducting a pump test on MW-1 to generate aquifer data for proper remediation design Perrrussnon for the pump test was ' granted by the San Joaquin County Environmental Health Department Total fecal coliform testing has been ordered as an addition to the next quarterly groundwater sampling event ' This will help resolve the question of a possible sewer leak 3.0 Scope of Work On December 22 & 23, 1994,WHF, Inc conducted a 24-hour pump test at this site MW-1, a 4-inch groundwater monitoring well, was the pumping well and four 2-ranch monitoring wells were measured as observation wells, MW4, 6, 7 & 8 All measurements were made with an electric sounder and recorded to 0 01 feet The pumping rate had been pre-tested on 12/20/94, and 5 0 gpm (gallons/minute) was selected as the optimum rate for the test The water pumpea curing the test was dark colored and nad a 'septic" odor All pumped -water was treated through carbon drums and stored on site in a Rain For Rent poly tank Analytical results were none-detected for BTEX and Gasoline(Appendix F)