2008-02-04_GENERAL DOCUMENTS - M1989056

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Table 2.1 Total Timnath Pit Compensatory Wetland Requirements. 0'-3' Wetland Wet Meadow Open Water Requirement 51.7 26.7 14.9 Two natural drainages that cross the property will be used to maintain the compensatory wetlands. Mallard Creek, which enters the property 1,050 feet south of the northwest corner, and Duck Creek, which enters the properly 1,335 feet north of the southwest corner will be subject to . channel relocation to facilitate mining. Following the completion of mining, the channels will be rebuilt in such a manner as to meander and maintain the compensatory wetlands. The slope of the channel will be maintained as close as possible to 0.001 feet/foot to insure drainage but reduce the flow velocity through the wetlands. In order to balance the wetland needs with economic concerns in the reclamation layout, the two creeks were aligned combined into a single channel near the c;enter of the property. The resulting channel exits the property 640 feet north of the southeast corner. The layout of the ponds included in the reclamation plan was limited to the area remaining after the removal of area for setbacks, development, and wetlands. Also, consideration was given to manageable pond size and enabling the possibility of gravity drainage. In the final reclamation plan, the ponds were positioned based on one constraint: the water storage area on the property should be maximized. Kehn owns 3 '/z shares of Boxelder Ditch water, whi~;h annually averages 323.8 AF of water that they may divert from the ditch. •Pending water court approval, Kehn intends to sell or lease 194 AF of this water for augmentation purposes. The remaining 129.5 AF of Boxelder water has to be released to the Poudre River pursuant to an augmentation plan submitted to water court and also pending approval. Care was taken in the layout of the ponds to insure that the Boxelder water could be effectively and affordably released to the Poudre River. It was assumed that the individual or entity that purchased or leased the storage ponds would be responsible for the pumping or other costs incurred moving water to and from storage. Embankment and liner design for the ponds is based upon the work performed by EEC. In their report dated June 11, 2003, EEC states that an adequate pond liner could be constructed using a mixture of overburden materials, bedrock, and aggregate from the site. The appropriate mixture of the materials was given as orie part overburden or bedrock to three parts aggregate. EEC is currently continuing work with on embankment design, and it is expected that they will recommend an embankment slope value on the order of one to three so layout and pond storage calculations have proceeded based upon this ratio. For further and more specific recommendations regarding the embankment and liner design, refer to the .EEC report included as Appendix D and future EEC reports to be submitted to Kehn. T:IOPEMCodhc011codhc0/finnlreporl.rloc 6 ANdER50N CONSULTING ENGINEERS, ANC.