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45 <br />• The distance to which drawdown of water levels would occur in the ) <br />stream deposits in Ennis Draw, should they be intersected by the pit, can- <br />not be estimated quantitatively, The drawdown due to pit inflow could <br />extend over a very large area depending upon the transmissivity of inter- <br />sected deposits. Again, it is recommended that special care be taken to <br />protect the waters in, Ennis Draw from significant disturbance by either <br />of the methods described previously. <br />C. Quality of 14ine Inflow <br />The quality of waters presently existing in the overburden and coal ~ <br />aquifers is shown in Table 3. Water seeping into the pit from the high- `~! <br />wall side will be a mixture of water from the coal seam and from the <br />overburden. Because the contribution from the coal seam will be quite <br />small relative to that from the overburden, the quality of the seepage <br />into the pit from the highwall will be essentially that of the existing <br />overburden waters. 1 <br />Seepage from the side of the pit opposite the highwall must pass ~ 1 <br />through the spoils before entering the pit. Experience with the quality <br />of waters passing through spoil banks formed from the Williams Fork form- <br />ation in western Colorado suggests that the effluent water will contain <br />dissolved solids at a concentration about equal to that in water equil- ~ <br />1 <br />ibrated with and saturating representative samples of the overburden. <br />Similar experience in the Fort Union formation suggests that water <br />saturating spoils will exhibit dissolved solids concentrations exceeding <br />that in saturation extracts by a factor of about 2. Table 5 shows the ~~ <br />pH and electrical conductivity (EC) of saturated extracts prepared from ~ <br />! composite grab samples taken from 3 cares in the Laramie formation. ) <br /> <br />