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~+E~~A <br />a7 c~fc~~~r Seneca Coal Company <br />March 7.2007 <br />Mx. Michael Boulay C <br />Colorado Division of Reclamation, Mining and Safety ~ECE.IVE~ <br />1313 Sherman Street, Room 215 MAR p g Zp01 <br />Denver, CO 80203 <br />DivMning and Safety n <br />Re: Seneca Coal Company <br />-- _ -I'ostmine Channel Design & -Permit Issues Meeting on March,5, 24[17-- _ - - - - - - <br />Dear Mr. Boulay: <br />Thank you for taking time Monday to meet with representatives of Seneca Coal Company (SCC). We <br />believe the discussions were very helpful and significant progress was made toward meeting SCC's intent <br />to utilize turf reinforcement matting (I'RM) material in the design and construction of postmine channels <br />at the Seneca II, Yoast and II-W Mines. However, before we move forward we want to assure that <br />Colorado Division of Reclamation, Mining and Safety (CDRMS) and SCC are in consensus as to what <br />was discussed and agreed to during our meeting. <br />The issues that were discussed and the agreed direction for SCC to proceed are as follows: <br />• CDRMS is receptive tc. use of TR"•~1s as a substitute for rock riprap where SCC can demrnstra±e that <br />the design is stable. <br />Design storm runoff values will be estimated based upon a revegetated watershed condition and <br />curve number inputs will be selected from the approved values which are found in the respective <br />permit application packages. <br />-- - - - •- Channel geometry- for TRM installation will be-based-upon equipment-limitations._ :i'rapezoidal- - --_ <br />shaped channels will have bottom widths of either three-feet or 10-feet. Side slopes will be 4H:1 V. <br />TRM installation will follow manufacturer's recommendations. The matting edge at the top of a <br />channel will be trenched. Matting margins at the top of channel banks will be covered with soil <br />material to facilitate sheet flow entering the channel over the mat and not undercutting the TRM. <br />• With the technical revision (T'R) applications, SCC will provide typical designs for vegetated, rock <br />riprap and TRM channels. Summary tables will be updated as appropriate. The TRM designs will be <br />generic so that SCC may use more than one TRM product. SCC will include manufacturers <br />specifications in either tabular ox text format to facilitate CDRMS review of the designs. <br />Manufacturer's literature may also be included as reference material <br />• Seneca Coal Company • P.O. Box 670 • Hayden, Colorado 81839 <br />• Telephone (970) 2763707 • FAX (970) 276-3014 <br />