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Mr Kyle Christie October 5, 1995 Page 2 wells were urged of a minimum of three well g P casino volumes or until evacuated using a pump or bailer Each well was sampled using a disposable bailer All groundwater samples were analyzed for benzene, toluene, ethylbenzene, and xylenes (BTEX) and total petroleum hydrocarbons as gasoline (TPH-G) by U S Environmental Protection Agency (EPA) Method 503018020, and 8015 Modified Field data sheets and chain- of-custody documentation are included in Exhibit A Results and Discussion The general groundwater flow direction beneath the site on July 27, 1995, was to the north and northeast under a hydraulic gradient of approximately 0 006 (Figure 1) Since groundwater monitoring began in April 1987, the general groundwater flow direction has ranged from north to east at this site The hydraulic gradient measured this quarter is within the range of previously reported gradients Depth-to-water on July 27, 1995 ranged from 9 43 feet below the top of the well casing{ TOC) in well ATR-11 to 13 22 feet below TOC in well ATR-1 Since the last quarterly monitoring event (April 26, 1995), water-level elevations in all the measured monitoring wells have decreased an average of 0 43 feet Summaries of depth-to-water measurements and calculated groundwater elevations are presented in Table 1 Table 2 presents past and present groundwater flow directions and hydraulic gradients for this site • Benzene was only detected in wells ATR-4 and SMW-1 The benzene concentration was 12 micrograms per liter (pg/L) in well ATR-4, and 410 pg/L in well SMW-1 These concentrations are within the range of previously reported values TPH-G was only detected in wells ATR-4, ATR-5, and SMW-1 The TPH-G concentration was 1700 pg/L in well ATR-4, 58 pg/L in well ATR-5, and 7400 pg/L in well SMW-1 These concentrations are consistent with previous values Analytical results of groundwater samples are summarized in Table 3 The complete laboratory report for the sampling event is presented in Exhibit A Figure 2 presents TPH-G and BTEX concentrations for the third quarter 1995 sampling event A soil vapor extraction and treatment/air sparging (SVET/AS) system has been designed and constructed for this site An Authonty-to-Construct permit (Permit No N-3413-1-0, issued March 10, 1995 and expiring March 10, 1997) has been obtained from the San Joaquin Valley Unified Air Pollution Control District for this site SVET/AS system start up is anticipated in the fourth quarter of 1995 Use or disclosure of data contained on this sheet is subject to the restriction specified at the beginning of this document 2G43`REPORTS�3RD95QRT DOC