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<br />• Error in volume Computations <br />The original volume computations for the Rienau #2 ponds A and B <br />were in error, because the operator neglected to draw the zero <br />contour line on the maps for these two ponds which led to an <br />erroneous volume computation. This explains the large discrepancy <br />between the DMG's calculations and the operator's. The operator <br />subsequently corrected the maps for these two ponds, and the <br />corrected maps were forwarded to the OSM office in Albuquerque. <br />Apparently, the corrected maps were not forwarded to the Western <br />Support Center. Copies of the corrected maps are enclosed. <br />With the corrected maps, there is no <br />discrepancy between the DMG's calculations <br />summary of the resul ts appears below: <br />Poad Enroa D?SG Standard <br />Rienau A 179 128 439 <br />Rienau B 217 135 691 <br />Northern fl 117 92 484 <br />Refuse 145 117 178 <br />Baseline Data <br />longer a significant <br />and the operator's. A <br />OSM expressed a concern that no baseline data were submitted for <br />the unmined watershed water quantity and quality. As discussed in <br />the April 15 meeting, the only surface water baseline data that are <br />available are from Curtis Creek which is in a different watershed <br />than the areas that drain into the sediment ponds. In any event, <br />stream water quality is not an appropriate indicator of surface <br />runoff quality. The ideal baseline database would include surface <br />water runoff quality during a storm event. However, these data are <br />not available; therefore, the models and sediment accumulation <br />measurements must be relied upon. <br />I hope this letter addresses all you concerns. If you have any <br />questions, please call me or Larry Routten at (303) 866-3567. <br />Sincerely, <br />Barbara L. Pavlik <br />Environmental Protection Specialist <br />enclosure <br />cc: Greg Lewicki <br />m:\coal\blp\c81032.osm <br /> <br />