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Mr. Larry Oehler <br />Division ojMinerals and Geology <br />September 30, 2004 <br />Page 2 oj2 <br />as wash water, returning to the ponds with suspended process fines. The circulation of water through the <br />processing facility will establish a pond surface elevation above the normal groundwater table. As the <br />process water circulates through the ponds, fines settling from the wash water will effectively block the <br />pore spaces in the alluvial material surrounding the ponds, reducing or eliminating groundwater <br />interaction with the ponds. Since groundwater will not be able to recharge the ponds, making up for <br />process evaporation losses, water will be added to the system periodically to maintain a constant pond <br />surface elevation. <br />The sedimentation ponds are not expected to have a significant effect on the alluvial groundwater at the <br />Pazkdale site, and it is very unlikely that impacts to groundwater would be observed outside the permit <br />boundary. As stated above, following startup of the wash water and sedimentation pond process, <br />groundwater interaction with the ponds is expected to be minimal. Once fines block the pore spaces in <br />the alluvial material surrounding the ponds, potential for the transport of suspended and dissolved <br />substances from the ponds to the alluvial groundwater is minimal If minor seepage of process water <br />from the sedimentation ponds did occur, suspended material would be physically removed by the <br />alluvium and dissolved constituents would be quickly diluted by the alluvial aquifer. It is expected that <br />these process would occur neaz the sedimentation ponds and affects to the alluvial groundwater aquifer <br />outside the permit boundary are not anticipated. <br />Additionally, hydrogeologic information presented in Gilmer Geophysics, Inc., Aydrogeology Summary <br />Report - Pazkdale Project, suggests that the alluvial groundwater flow is southerly and south- <br />southeasterly beneath the project site. The groundwater gradient is towazds the Arkansas River and <br />Tallahassee Creek confluence where the alluvium and alluvial groundwater pinch out. In this area down <br />gradient of the project site, there are no registered or known groundwater wells. in use. Therefore, it is <br />highly unlikely that operation of the sedimentation ponds would have a negative impact on water resource <br />beneficial uses. <br />The sedimentation ponds will only cover about 0.5 acres and will be located in the bottom of the existing <br />sand and gravel pit. The location and relatively small size of the ponds would minimize the work and <br />backfill necessary to reclaim the ponds. Therefore, we believe that no additional security bond is <br />necessary for this technical revision. <br />If you have any questions regarding this technical revision, please do not hesitate to call me at (303) 452- <br />6611. <br />Sincerely, <br />Applegate Gr p, c <br />~~ i <br />William Schenderlein, P.E. <br />Project Engineer <br />WKS/ta <br />Enclosures <br />cc: AG File # 04-113 <br />Mr. Tom Maul, Fron[ Range Aggregates, LLC <br />N:\04113 Parkdale Quazry\Disciplines (rechniral)Vvfine PlavnivgnR letter.doc <br />