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Mr Kyle Christie August 24, 1995 Page 2 Field and Analytical Methods EMCON personnel measured depth-to-water and product thickness (wren present), purged each well to be sampled, and collected groundwater samples at the site Before sampling, the wells were purged of a minimum of three well casing volumes or until evacuated using a submersible pump or bailer After purging, each well was sampled using a disposable bailer Field data sheets and chain-of-custody documentation are included in Exhibit A 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 Results and Discussion The general groundwater flow direction beneath the site on June 1, 1995, was to the northeast under a hydraulic gradient of approximately 0 004 to 0 007 (Figure 1) The gradient was relatively flat across the site, and steepened northeast of the site Well E-10 was not used in contouring because according to EMCON's field notes, the free product thickness was measured after one bailer of purge water was removed from the well Therefore the water level and product thickness recorded by EMCON may not represent static conditions Water- level elevations to Table 1 are corrected for the presence of free product, but because the free • product thickness in well E-10 may not be accurate, the calculated groundwater elevation may also not be accurate Summaries of depth-to-water measurements and calculated groundwater elevations are presented in Table 1 Since groundwater monitoring began in 1989, the general groundwater flow direction has been to the northeast at this site, under hydraulic gradients ranging from 0 001 to 0 005 Table 2 lists historical groundwater flow directions and hydraulic gradients for this site Depth-to-water on June 1, 1995 ranged from 11 09 feet below the top of the well casing (TOC) in well PR-2, to 14 49 feet below TOC in well E-10 Well E-10 contained approximately 2 74 feet of free product on June 1, 1995 Since the last quarterly monitoring event (March 8, 1995), water-level elevations in all monitoring wells (except E-6 , E-10, and MW-2) increased an average of 151 feet Water-level data was not collected from wells E-6 and MW-2 because the wells are tied into the soil vapor extraction system, and were not accessible to EMCON The water-level elevation in E-10 decreased 0 71 feet (decrease may be due to presence of free product.) Benzene was not detected in wells E-7, E-12, PR-1, PR-2, BHD-2, MW-1, MW-3, and MW-4, but was detected in wells E-2, E-3, E-4, E-5, E-8, E-9, E-11, BHD-1, and MW-5 at concentrations ranging from 69 micrograms per liter (pg/1) in well E-5 to 1900 µg/1 in well E-3 With the exception of well E-5, these results are consistent with previous results The benzene concentration in well E-5 is the lowest it has been since sampling began in 1988 Use or disclosure of data contained on this sheet is subject to lice restriction specified at lite beginning of this document 2WMZEPORTS\2\D95QTR RPI