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i L Can epa Is Car Wash 6230 Pacific Avenue, Stockton, California ' Quarterly Groundwater Sampling Report December, 1994 I I Narrative ' On December 8, 1994, WIT Environmental Consultants, Inc , in conjunction with HKM Groundwater Monitoring, conducted field measurements, well pumping and groundwater ' sampling on eight (8) groundwater monitoring wells located at this site (Figures 1 & 2) Groundwater elevations were taken from eight (8) wells prior to pumping (Table 1 & ' Appendix B) Monitoring wells MW-1 through MW-8 were evacuated by means of a steam-cleaned, stainless steel bladder type pump During the three (3) volume pump down of each well, samples were collected to measure field pH, electrical conductivity and temperature (Table 3 & Appendix B) Once stability was achieved, a minimum of three (3) well volumes were removed and samples were collected with a steam-cleaned disposable bailer The samples were then labeled and placed in an ice chest cooled with ' blue ice The samples, bailer blanks and trip blank were then logged on a Chain of Custody ' (Appendix A) and transported to the State-certified laboratory, California Laboratory Services, in Rancho Cordova, California The analysis requested for the water samples was EPA method 602 for BTX&E and EPA method GCFID (5030/8015) for gasoline ' The analytes and concentrations detected are listed in Table 2 of this report ' Groundwater Gradient The water level measurements from the monitoring wells were used to construct a groundwater gradient map and calculate the gradient (Figure 3) Water levels rose between 0 99 and 1 11 feet, averaging 1 05 feet across the site The mound in the water table is evident again this quarter with variable gradients and directions Because the iMBAS tests, which would have detected the detergents used in the car wash, were negative on the last sampling event, total ec test will be incorporated into the next sampling event This will hep determine if there is a sewer leak at this s.te Historical gradient maps are included in Appendix C 1