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Well RW4 will extend the capture zone farther in the downgradient direction, but based on this well log, its maximum pumping rate will be much lower than that of RW 1, RW2, or RW3 ' Furthermore, well V1, which is completed as a recovery well, will produce little water because the saturated zone in this strata consists mostly of silty clay Well V 1 will be used to lower the ' water table in the area if it is necessary to expose hydrocarbons presently entrapped below the water table in order to remove them more easily using the soil vapor recovery system ' 1.4.3 Percolation Test ' Field Methods Also on 20 September 1990, an infection test was conducted in well MW7 in order to properly size an injection trench or to establish that a series of injection wells located along the western property line would be sufficient to generate a hydrogeologic mound, or barrier, to prevent hydrocarbons from an upgradient source (identified in MW8) from being pulled under the site ' Tap water was injected into well MW7 at the rate of 7 5 gpm for 155 minutes (2-1/2 hours) Water level measurements were recorded every 15 minutes during the test The results of well gauging in MW1 (drawdown vs time) were used to determine transmissivity of the saturated and ' unsaturated zones under the site. The computer program WHIP (Well Hydraulic Interpretation Program; Hydro-Geo Chem , Inc 1988) was used to interpret the data This program uses the Jacob-Cooper method for initial estimation of transmissivity and storativity; these values are then refined by iterative automatic ' parameter estimations (IPE) In the IPE, mean aquifer parameters are refined by using the Levenberg-Marquardt version of Newton's nonlinear iterative optimization algorithm tAnalysis ' The maximum sustained volume of water (Q) that can be injected into well MW 1 can be calcu- lated from the equation ' Q = K(hW 2- H02)/[0.733(log r./r")] (Driscoll 1986) where K = hydraulic conductivity 3 04 m/day, for saturated and unsaturated zone h = head above the bottom of aquifer while recharging (15 m) ' Ido = head above the bottom of aquifer when no pumping is taking place (6 1 m)r = radius of influence (-30 m [assumed]) r w = radius of injection well (0.127 m) For the assumed values of K and a 5-m "mound" (greater elevation) above the static water level in the well, about 310 m3/day (58 gpm) of water could be injected into the well. This might be adequate for the conditions encountered during the percolation test, when the sediment above the � W-Wf73%Ujul9th. 9