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a =area = w width x d depth of alluvium, d = 20 feet <br />h= elevation difference of potentiometric head between wells = 10 feet <br />1 =horizontal distance between wells = 640 feet <br />Total flow through the alluvium: <br />Q =(0.00194)(500)(20)(10)/(640) = 0.303 CFS = 136 gpm <br />Total flow subject to contamination: <br />Q =(0.00194)(150)(20)(10)/(640) = 0.091 CFS = 41 gpm <br />Comparison of the calculated total flow through the alluvium (.303 CFS) with the <br />average minimum flow recorded for the North Fork of the Gunnison River (39.09 <br />CFS) indicates flow in the river may be nearly 130 times the amount passing through <br />the alluvium at record low flow. Flow in the North Fork of the Gunnison River <br />averages 433 CFS. The larger flows present in the river are predicted to dilute any <br />contaminants which may enter the river from the alluvium. <br />As presented in Section 2.05.6(3), the low flow through the alluvium indicates why <br />well AA 1 shows signs of degradation. There is not adequate flow to flush the <br />contaminants through the alluvium. Because the flow is low, water which flows <br />from the alluvium is not predicted to have a measurable impact on the quality of <br />water in the North Fork of the Gunnison River. This can be further demonstrated <br />as follows: <br />Stream Flow (CFS) TDS (Mg/I) <br />Alluvium 0.091 2800 <br />NF Gunnison 21 196 <br />Weighted Average 21.091 207 <br />Minimum river flow - 21 CFS USGS Gauging Station 1976 - 1989. The value for <br />Total Dissolved Solids (TDS) concentration for [he river is the maximum value from <br />Somerset Mining Company's North Fork #2 monitoring point through 1992. The <br />TDS concentration for AA 1 is the maximum value for the period 1983 though 1992. <br />Based on this analysis, the flow of contaminants from the alluvium into the North <br />Fork of the Gunnison River are not anticipated to have a measurable impact on the <br />quality of water in the river. Because the coal stockpile has been removed during <br />recent reclamation of the Beaz No. 3 site, there is a very low potential for significant <br />impacts to groundwater in the alluvial material underlying the Bear facilities. <br />34 <br />