ARCHIVED REPORTS_XR0009617 - Laserfiche WebLink

Home Browse Search

QUARTERLY MONITORING REPORT JULY 1997 CANEPA'S CAR WASH 248 E Park Street Stockton CA August 12 1997 Page-5- TABLE 1 Groundwater Elevation Data (July 21, 1997) ' MW-1 through MW-7 I Well Well Casing Well Collar Depth to Groundwater ID Screen Elevation Water Elevation Interval (feet) (feet) (feet) (feet - bgs) ' MW-1 45 - 65 1097 2897 -1800 MW-2 45 - 65 1037 2993 -1956 MW-3 45 - 65 1176 3056 -1880 MW-4 40 - 60 1085 2853 -1768 MW-5 40 - 60 1125 3049 -1924 MW-6 40 - 60 1172 3051 -1879 MW-7 40 - 60 1105 2934 -1829 S 0 DISCUSSION OF RESULTS Since the August, 1995, quarterly monitoring, the elevation of the water table has Increased approximately 10 feet Since September, 1994, the depth to groundwater at the site has ranged from approximately 45 feet to 29 feet bgs The groundwater elevation contour map (Figure 3, Appendix A) indicates that groundwater flows northeast and northwest toward the general vicinity of MW-2 This ' is generally consistent with previous monitoring results A hydrograph of monitor wells MW-1 through MW-7 (Figure 4, Appendix A) illustrates the fluctuation of the groundwater table Historical groundwater measurements are provided in the accompanying Hydrograph Table ' The results of the laboratory analyses Indicate that TPH-G, BTEX, and possibly MTBE were detected in groundwater samples collected during the July, 1997 sampling event Benzene concentrations detected in all wells, except MW-7, exceed the maximum contaminant level (MCL) for benzene (1 0 I µg/L) in drinking water (California Code of Regulations, Title 22, Drinking Water Regulatory Criteria) No MCL has yet been established for MTBE The California Department of Health Services has set an action level of 35 gg/L for MTBE In drinking water Although unconfirmed, MTBE concentrations have been detected in the groundwater samples from the site monitor wells exceeding the action level Future analysis using EPA Method 8260 may Indicate that MTBE is not present in the groundwater IAnalytical results for the July, 1997, sampling are generally consistent with historical analytical results TPH-G and BTEX concentrations in the sample collected from MW-5 have Increased markedly since August of 1995 MW-5 is generally down-gradient from the former Iocation of the underground Page -5- A��o V% CONDOR