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Mr Chuck Carmel November 8, 1993 Page 2 and xylenes (BTEX) by U S Environmental Protection Agency (EPA) Method 5030/8020/ DHS LUFT Field data sheets and the chain-of-custody form are included in Exhibit A Results The general groundwater flow beneath the site on August 30, 1993, was to the north under an average hydraulic gradient of 0 003 (Figure 1) A summary of depth-to-water measurements and calculated groundwater elevations is presented in Table 1 Table 2 lists past and present groundwater flow directions and hydraulic gradients for this site 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 shows TPH-G and BTEX concentrations for the August 30 and 31, 1993, sampling event Figure 3 is a benzene isoconcentration map Benzene concentrations ranged from nondetectable in several wells to 33 micrograms per liter (pg/1) in ATR-4 TPH-G concentrations ranged from nondetectable in several wells to 700 pg/l in well ATR-8 The detection limits for the BTEX constituents and for TPH-G are 0 5 and 50 lig/I, respectively Approximately 0 01 feet of free product was measured in ATR-3 Discussion Water level elevations have decreased an average of 0 79 feet across the site since April 14, 1993 The northerly groundwater flow direction and the hydraulic gradient (0 003) are consistent with previously reported data Concentrations of hydrocarbon constituents were nondetectable in samples collected from on- site monitoring wells ATR-1, ATR-2, and ATR-7 and oft-site monitoring wells ATR-9 through ATR-12 BTEX and TPH-G concentrations in wells ATR-4 and ATR-5 are within the range of previously reported values The toluene concentration in the sample from ATR-8 is higher than previously reported concentrations, but all other BTEX and TPH-G concentrations were within the range of previously reported values for this well Well ATR-3 has not been sampled since the fourth quarter of 1991 due to a trace of free product (thickness approximately 0 02 feet) found each quarterly trampling period Use or disclosure of data contained on i1irs street is subject to the restriction specified at the beginning of this �! document 74031RLPORTSIAUG93QTR RFT