Laserfiche WebLink
<br />extent of ee~ch surface within and proximate to the permit <br />area. <br />Although some seasonal variability has been observed at select <br />wells, the effects of this variat~ility on the depicted <br />potentiometric surfaces is minimal, limited to small changes <br />in local gradients. The following calculations demonstrate <br />this point. Gradients were measured bbetween the wells listed <br />below based on the potentiometric surfaces depicted on <br />Exhibits 7-?, through 7-4. Again, the surfaces were <br />constructed using the overall arithmetic means of valid water <br />levels. A second set of gradients between the same wells were <br />calculated u:ainq only valid baseline water levels collected <br />during the sF~ring season (March 15 to July 1). <br />Spring Season <br />Mao Giradient Gradient <br />YOV27-YOV28 (WZ;dge Overburden) .1637 ft/ft .1613 ft/ft <br />YW26-YW28 (Wadc~e Coal) .151.1 ft/ft .1523 ft/ft <br />YWU17-YWU30 (Wedge Underburden) .131.0 ft/ft .1303 ft/ft <br />The gradients calculated above using spring season water <br />levels were ;Tightly lower between t:he Wadge overburden and <br />underburden wells, and were slightly higher between the Wadge <br />coal wells. In no instance were the differences in gradients <br />(ft/ft) greater than .0024, which is a minimal difference. <br />19. During the February 1, 1995 meeting bentween SCC and the CDMG, <br />the CDMG admitted the exhibits which show the potentiometric <br />surfaces were temporarily misplaced, have been located, and do <br />not need to tie provided. <br />20. SCC has revised the "Introduction" to the "Site-Specific <br />Hydrogeology" section of Tab 7 to provide more specific <br />identification of geologic units monitored at the Yoast Mine <br />and how these; units compare stratigr;sphically with regional <br />stratigraphy and aquifers. <br />21. Pages 39, 41, 42, 43, 46, 47, 48, 50, :51, and 54 of Tab 7 have <br />been modified to explain the significance of 1 mg/1 in the <br />ground water quality discussion. <br />22. Laboratory ar;alytical techniques commonly used by contract <br />laboratories:Eor trace metals occasionally require dilution of <br />the sample analyte in order to obtain reliable measurements, <br />depending on the instrumentation and the presence of <br />additional metals and compounds in the: sample. This dilution <br />process may result in an occasional report of a higher <br />detection limit if the analysis finds no detectable <br />concentration of the trace metal. <br />• <br />• <br />• <br />