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Mr Chuck Carmel March 26, 1993 i r� Page 2 Results The general groundwater flow across the site is to the south-southwest with an average hydraulic gradient of 0 002 Water level data are listed in Table 1. Table 2 shows past and present hydraulic gradients and groundwater flow directions Figure 1 illustrates groundwater contours and the groundwater flow direction Well W-2B was not used for contouring, as this well is completed in a deeper zone than the other wells Current and historical analytical results are summarized in Table 3 The November 1992 analytical results are shown on Figure 2 Figure 3 illustrates logarithmic contouring of benzene data for the November 1992 sampling event Again, well W-2B was not used for contouring as it is not completed in the same zone as the other wells The complete laboratory report for the November 1992 sampling as presented in Exhibit A A summary of the remediation system operations for the fourth quarter is provided in Table 4 for soil and Table 5 for groundwater. Figure 4 and 5 summarize the cumulative amount of TPH-G removed from the soil and groundwater since the soil vapor and groundwater treatment systems were started m July 1991 and October 1992, respectively. Discussion The direction of groundwater flow at this site continues to be to the southwest under a gradient of 0 002 On November 16 and 17, 1992, the depth to water ranged from 65 01 feet to 67 79 feet Water levels in the monitoring wells increased an average of 0 16 feet between August and November 1992. BETX and TPH-G constituents were not detected in groundwater samples collected from monitoring wells W-lA, W-2B, W-5, W-6, W-7, W-8, and W-9. Compared to the August 1992 sampling results, BETX constituent and TPH-G concentrations have remained nondetectable or decreased in wells W-3, W-10, and W-12. A small increase in TPH-G concentration was measured for well W-11 Wells W-11 and W-10 are located upgradient of the site and therefore the hydrocarbon constituents identified in these wells may not be related to this site Well W-12 is located cross-gradient from the site and adjacent to a Shell service station Status of Site Remediation A vapor extraction and treatment system has been operating at this site since July 1991 As of December 14, 1992, approximately 38,680 pounds of hydrocarbons had been extracted and treated from site soils. A groundwater extraction and treatment system has been in operation at the site since October 1992 As of January 5, 1993, a total of 78,700 gallons of groundwater had been extracted and treated In an effort to increase influent concentrations . to the groundwater treatment system, groundwater extraction will be pulsed on a weekly basis (on for a week, off for a week). Brown and Caldwell 03 PAEPMTS%MV92QnRxrr Consultants