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Quarterl}Monitoring Report April 1999 Canepa s Car Wash(Part.Street) Mai 31 1999 Page 2 31 Groundwater Monitoring Obsei ,ations and Parametei s ' The static water level in each well was measured to the nearest 0 0I-foot with a battery-operated, flat tape, water-level meter A clean, single-use, polypropylene, disposable bailer was lowered into each well to check for floating product, petroleum odors, and sheen Floating product was not observed in any of the monitor ' wells during the groundwater sampling It should be noted that the groundwater table was above the top of the well screens Mild petroleum hydrocarbon odors were detected in the groundwater samples collected from MW-2 and MW-5 Petroleum hydrocarbon odors were not noted in the remaining groundwater samples ' All of the monitor wells were purged using new disposable bailers Approximately three well casing volumes of water weie purged from each well (see the Groundwater Monitoring Field Porins in Appendix B) The ' purged water from each well was placed in 55-gallon drums and left on site pending laboratory analytical i esults ' 3 2 Groundwater Sampling Each well was allowed to recover to at least 80% of its pre-purge water level before sampling The groundwater samples were collected directly from disposable bailers by transferring the groundwater to two 40- ' milliliter glass vials The sample containers were labeled, placed in a cooler chilled with ice, and delivered in accordance with chain-of-custody procedures to GeoAnalytical Laboratories, Inc , in Modesto, California, on the days of collection 4 GROUNDWATER MONITORING RESULTS 4 1 Groundwater Elevation Contours On April 22, 1999 the depth to groundwater was measured in each monitor well prior to the collection of groundwater samples Evaluation of the groundwater measurements collected on April 22, 1999 indicated the likelihood of an eironeous measurement rec.oided for MW-4 Consequently, depth to groundwater measurements were collected from the seven monitor wells on May 4, 1999 The data collected on May 4, 1999 is consistent with historical data collected at the site with respect to the estimated groundwater gradient The average depth to groundwater on May 4, 1999 was approximately 22 8 feet below the well measuring points (slightly below the ground surface) The average depth to groundwater decreased approximately 1 3 feet ' since the previous monitoring event conducted in January, 1999 The groundwater elevation ranged from 10 96 to 12 63 feet below mean sea level (bmsl) The groundwater elevation contour map (Figure 3, Appendix A) indicates a groundwater gradient generally toward the northeast See Table 1, on the following page, for Igroundwater elevation data A hydrograph of groundwater elevations is included as Figure 4, Appendix A I t CONDOR