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<br />Only the Sudduth coal seam is significant. Using worst case con- <br />ditions, the applicant calculates an average of 2,400 gal/day <br />will be intercepted in Pit 1. This is a limited impact, as min- <br />ing in Pit 1 is nearing completion. For Pit 2, a maximum of <br />1,435 gal/day will be intercepted due to mining operations <br />(determined from aquifer testing, Vol. I of the permit applica- <br />tion, Report on Determination of the Probable Hydrologic Conse- <br />quences of Mining). The total groundwater inflow in barely <br />sufficient to meet dust suppression needs. The applicant has <br />committed to storing inflow waters from the pits in sedimentation <br />ponds. Sufficient capacity has not been included in all pond <br />designs to handle the estimated pit flow, as discussed in the <br />Surface Water section of this TEA. <br />There are no underground mines, active or abandoned, within <br />or near the permit area. Therefore, no impacts related to inter- <br />cepting underground workings will be realized at the Canadian <br />Strip Mine. The applicant is in compliance with Section 4.05.16. <br />An impact that surface mining activities invariably have on <br />yroundwater involves a basic liability associated with removing <br />the coal. When low-permeability undisturbed rock formations (the <br />overburden in this instance) are replaced with higher permeabili- <br />ty spoil material, vertical infiltration and percolation of sur- <br />face water (from precipitation and snowmelt events) is promoted. <br />The result is spoilwater with high TDS concentrations that can <br />cause degradation of water quality both down-gradient and down- <br />stream. <br />The chemical analyses of overburden samples demonstrate the <br />potential for a toxicity problem associated with sodium. Sodium <br />absorption ratios (SAR) are extremely high (ranging from 7.7 to <br />43.9 in Pit 1 and 2.7 to 76 in Pit 2) near the nose of the <br />anticline and tend to decrease rapidly northwest up both flanks. <br />The applicant states that "because the .sodium seems to be fairly <br />evenly distributed throughout the stratigraphic section (espec- <br />-80- <br />