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. A S S O C I A T E S I N C In July 1994, a RESNA field geologist observed the drilling of four additional groundwater monitoring wells (MW4, MW5, MW6, and MW7) at the site to further characterize subsurface conditions Groundwater samples collected from these additional wells contained no detectable petroleum hydrocarbons A detailed discussion of the Phase 2 Subsurface Investigation can be found in RESNA's "Summary Report, July 1994 Investigation, " dated August 26, 1994 In PHS/EHD correspondence dated March 1995, regulatory approval was given to sample wells MW3 and MW5 and wells MW4, MW6 and MW7 on an alternating semi-annual basis MW 1 and MW2 were to be sampled every quarter, conditions permitting To further define the extent of residual soil contamination in the vicinity of the former underground fuel storage tank (UST), Smith Technology supervised the advancement of four soil borings (SB-1, SB-2, SB-3, and SB-4) on February 29, 1996 to depths of approximately 16 to 26 feet below ground surface (bgs) Total petroleum hydrocarbons as gasoline (TPHg), benzene, toluene, ethylbenzene, and xylenes (BTEX) were detected above method detection limits at low to moderate concentrations in samples collected at depths between 10 and 15 feet bgs in borings SB-1, SB-2, and SB-3 A detailed discussion of this subsurface investigation can be found in Smith Technology's"Subsurface Invest.-gation Report, " dated April 30, 1996 I . GROUNDWATER MONITORING AND SAMPLING Smith Technology personnel performed groundwater monitoring and sampling on June 27, 1997 Field work consisted of measuring the depth-to-water in wells MW 1, MW2, MW3, MW4, MW5, MW6, and MW7, using an electronic water/product interface probe to determine if free product was present, purging and sampling wells MW1, MW2, MW3, and MW5, and subjectively evaluating collected water samples for the presence of petroleum hydrocarbon constituents Static groundwater elevations were measured 1n each monitoring well on June 27, 1997 Groundwater was measured at approximately 12 5 feet below grade The groundwater gradient map was created with the June 27, 1997 data using a computer kriging program The gradient map, presented as Figure 2, depicts a southwesterly groundwater gradient averaging 0 004 ft/ft or approximately 23 feet/mile Fluid level measurements indicate groundwater flow direction beneath the site dunng this reporting period 1s generally consistent with historical data Groundwater has decreased an average of 0 59 feet since the previous measurements were collected in December 1996 The electronic water/product interface probe employed at the site, with an accuracy of 0 01 foot, detected 0 01 feet of free product in well MW2 Groundwater monitoring data are summarized in Table 1 • 943341QUARTLY12QR-1997 DOC 2