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_ 2- RWgCB has questioned thevalidity_� thQ NF_groundwater gradient direction reported in the August 1989 EA� r p, The groundwater elevations in that report were calculated from EA gauging data and using wellhead elevations sur- veyed by GTI in 1987 (GTI 1987). Due to a typographical error in the "Wellhead Elevation" column of Table 2 of F the August 1989 EA report, the water elevation in MW2 was ' incorrectly reported as being one foot lower than its I actual elevation for four of the five gauging dates, beginning with the 26 August 1988 values: This unusually low elevation led RWQCB to conclude that MW2 had been completed in an aquifer different from the aquifer inter 1 6 cepted by the other wells, and to comment that valid gradient determinations can only be determined from wells which are screened in the same hydrologic unit. t In order ,to eliminate any question about the downgradient di tion rec EA personnel resurveyed the wellhead elevations of the five wells: on 7 February 1989. The new wellhead elevations and the gauging data from the. last two years rs are shown in Table 2. The survey confirmed that: the water table in MW2 was indeed higher than it had. been reported,' p and that its elevation was very close to that of the other wells. Fig ure 1 shows aplan tan with groundwater elevation contours derived from the most recent gauging data on .14 February. 1990. The contours indicate that the downgradient direction is ;presently toward the northeast. Appendix C contains site plans showing groundwater elevations and the gradient calculations for each of the sets of gauging data collected over. the last two years.: The groundwater gradient direction was calculated by contouring the surface of the water table whenever possible: Where the groundwater elevation values did not permit smooth contouring, the downgradient direction was calculated using the three-point e35/71050/2--90/tx 7 r; �t