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' Oct 10 1996 r 20PM IEi, TECHNOLOGIES N0 ;9;4 P 49/54 of 5H from the well and for a constant ratio of a/H = 0.25 (screen length over aquifer thickness) The results are discussed for wells which pump upward. F---B-r---f H A L �8 z 8 uve ar A --� z • --Ba p B1 4 ' UVB UVB ' Figure 10 Notations in an upstream cross section through the capture zone for one and two UVB installations (for wells pumping upward). The widths BT and BB of the upstream capture zone, measured at the aquifer top and bottom, are shown in Figure Ila. The ratios Br/H and BS/H are dependent on the ratios Q/(Hv), KH/K,,, and a/H. v denotes the Darcy velocity of the natural groundwater flow; all other variables are explained above. For small values of Q/(H2v), the upper part of the capture zone does not reach the top of the aquifer. This implies that for remediating a plume, a minimum well discharge (Q) is required. Again, the results are quite sensitive to the degree of the anisotropy (see Fig. 5, as well). Figure llb shows the results for the influx area (A) of the upstream capture zone, and Figure I 1 c the maximum well distance,(D) of two wells between which contaminated groundwater cannot pass without being treated. The ratios AIW as well as D/H are dependent on the same parameters as the,widths BT and Be. When a plume of width W 1 is to be cleaned, the number (n) of UVB installations can be estimated by n = (W-BT)/D+I. When a plume is remediated, the contaminated water of quantity Q„ flowing into the capture zone of a UVB from upstream, is,diluted with water that has already flowed through the well and circulates around the UVB. Thus, the contaminant concentration of the water within the well casing will be lower than in the upstream plume; near a contamination source the situation is contrary, Figure l ld illustrates the portion Q.of the total well discharge Q.The ratio QJQ is again dependent on the same parameters as the ' widths of the upstream capture zone. Figure lld can be used to estunate the expected concentration value of the water within the well casing for the dimensioning of a UVB installation. It may help to evaluate the progress of remediation at a site when ' concentration data of the upstream plume and the water within the well are determined In Figure 12 the upstream distance (S) of the stagnation point at the aquifer top from the well axis is described (see Fig 3b and 3c, as welI). The ratio SIH is also dependent on the parameters Q/(H'v), Ki;/K,,, and a/H. The location of the stagnation 1}.