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wherein: Ca =concentration in river with the degraded water Cb =concentration in river without the degraded water Cv, =concentration in drainage from the waste Q =average stream discharge Q~v =average discharge of water draining from the waste dC =increase in concentration in the river The mean flow at the Purgatoire River was previously estimated to be 20 cfs (see Maxwell Permit Application, Volume 1, Exhibit 6, Page 41). The average yearly discharge of drainage from the dump is Qw = 18.4 x 43560 - 0.025 cfs (365)(86400) The quality of the water drained from the waste is assumed to be that measured in a seep from the Allen Mine waste dump. The following changes are computed: Parameter Cw m /1 C m /1 TDS 2600 3.3 504 1023 1.3 HCO3 827 1.1 Na 1028 1.3 Fe 0.81 0 Mn 0.04 0 If it is conservatively assumed that drainage occurs within one month after the water table recedes, then Qw =(18.4)(43560)_ 0.14 cfs (360(86400) (30~ Since drainage is assumed to occur over a thirty day period, flow in the river will probably be greater than the 20 cfs mean annual discharge of the Purgatoire River. Therefore, the results of the calculations presented in the following table are conservative. Parameter Cw, mg/1 pC, mg/1 TDS 2600 18 SO4 1023 7.2 HC03 827 5.8 Na 1028 7.3 Fe 0.81 0 MN 0.04 0 These last values represent a worst possible case. Under no circumstances can we visualize the capillary water draining appreciably, yet we have assumed it drains completely in 30 days in the second calculation. As.illustrated by the attached figure, capillary water will not drain appreciably because the underlying gravel near the interface will drain readily as the water table recedes. This, in turn, results in a greatly reduced permeability in the gravel near the interface. The zone of reduced permeability acts as a barrier to drainage of the overlying fine grained material.