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' QUARTERLY MONITORING REPORT JULY 1997 CANEPA 5 CAR WASH 248 E Park Street Stockton CA August 12 1997 ' Page-4- TABLE 1 Groundwater Analytical Results (July, 1997) ' MW-1 through MW-7 B T E A MTBE TPH-G ' MONITOR Detection 03 03 03 06 10 005 WELL/SAMPLE DATE Limits gg/l µgll gg/] ggfl µg/1 mg/l Sample ID ' MW-1 7/21/97 2038-MW 1-7/21/97 1 2 40 1 2 1 6 44 030 MW-2 7121/97 2038-MW2-7/21/97 670 490 550 1,200 240* 21 ' MW-3 7/21197 2038-MW3-7/21/97 13 20 10 25 11 14 088 MW4 7/21/97 2038-MW4-7/21/97 20 26 03 1 8 12 ND MW-5 7/21/97 2038-MWS-7/21/97 1,300 3 000 600 910 ND 14 MW-6 7/21/97 2038-MW6-7/21/97 1 $ 141 14 22 86 0 10 MW-7 7/21/97 2038-MW7-7/21/97 04 1 6 ND ND 3 6 013 Unit Conversions Anahnical g9/1 parts per billion (ppb) B,T E X =benzene, toluene, ethyl benzene, and xylene mg/l parts per million(ppm) TPH-G=total petroleum hydrocarbons,quantified as gasoline MTBE W methyl tertiary bury] ether ND=none detected at or above reported laboratory detection limit *=EPA Method 602 indicated that MTBE was present at 240 pg/L, However, EPA Method 8260 indicated in the previous monitoring event that MTBE was not present in the monitor well at or above the laboratory reported detection limits 4 3 Groundwater Gradient On July 21, 1997, the depth to groundwater was measured in each monitor well prior to the collection of groundwater samples The average depth to groundwater was approximately 29 8 feet below the ground surface (bgs) at the site Because monitor wells MW-1, MW-2, and MW-3 are I screened from approximately 45 to 65 feet bgs, and monitor wells MW-4, MW-5, MW-6, and MW-7 are screened from approximately 40 to 60 feet bgs, the water level was above the top of the screen in each of the wells The groundwater elevation ranged from 19 56 to 17 68 feet below sea level (bms]) See Table 2, below for groundwater elevation data Groundwater elevation contours are shown in Figure 3, Appendix A The groundwater elevation contours are generally consistent with historical results, indicating northeast and northwest groundwater flow towards the general vicinity of MW-2 A hydrograph of groundwater elevations is included as Figure 4, Appendix A The accompanying Hydrograph Table includes historical groundwater elevation data Page -4- tJ CONDOR