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ECG NECi4 <br />s coalcotnpem' Seneca Coal Company <br />January 11, 2007 <br />Mr. Daniel Mathews <br />Division of Reclamation, Mining and Safety <br />101 South 3~, Suite 301 <br />Grand Junction, CO 81501 <br />(970)242-5025 <br />oi~s,o AN ~ 12001 <br />Mining and Sa ery n. <br />RE: Seneca II-W Mine (Permit C-1982-057) <br />Technical Revision No. 55 (TR-55) Slide Remediadon Plan <br />2nd Response to Comments <br />Mr. Mathews, <br />Seneca Coal Company (SCC) has reviewed your fax regarding Technical Revision 55, Slide Remediation Plan, <br />dated October 17, 2006, and is providing the following responses to the comments. We have prepared the <br />following responses to your comments. <br />1. The referenced amended plan view sketch `Remediation Plan View" depicting the various roadside dt7cher and culverXr described <br />will need to be provided <br />Response: An updated "Remediation Plan View" is attached that addresses, at a minimum, your concerns. <br />2 Steve Renner tired Enkamat 7020 "roil filling"installation option in cl~anne! imrtallationr at Caal Basin. The .spec rheetyou <br />had provided to me during my September inspection war for Enkamat 7003. 7020 it a heavier, thicker mat; listed appGcationr <br />are for vegetated channels with expected .shear rtnu of up to lOprf, and permanent erosion contra! for moderate to steep slopes (up <br />to 1.5:1). 7003specr are for channeG with shear strew up to 6psf and slight to moderate slopes up to 3.5:1. This would seem to <br />indicate that Enkamat 7020 would be a better choice for the 77-W rite. Your k#er did not indicate whetheryou wen planning to <br />use the ".roil filling" option or `non-roil filling': The Enkamat brochure I have states that `ioi! filling accekmter performance <br />because the Enkamat, roil and the new vegetation interact together to resist shear forcer when mater it flowtng through the channel <br />or on top of a slope. If mil fzlling it utilised, reread % to '/. inches of fine roil into the mat to completely fill it. " I wiU fax to you <br />a copy of the bsochun I am taking this information firm. Seeding would be done either after roil frll, or both before and after roil <br />fzll (in either care, seed over the top of the installed mat. Non-.roil ftll is only recommended in .rttuations where the mat would be <br />expected to trap sediment fmm an up-gradient roaerce. Even for tlx non-roil fill, reeding it to be done over the top of the installed <br />mat (apparently, the effectiveness of the mat is dependent an roatrgroming dawn through the nylon matrix). Obviously, the roil fill <br />optzon would be more labor intensive, but would appear to be more effective in tbzr situation. In any event, the specs for <br />the rurfrein£orcementmot to be installed will need to be sped&ed and demonstrated to be adequate <br />for the anticipated slope and channel conditions, and the installation procedure (eg. "soil filled" of <br />"non-soil filled') will need to be specified and jusrified. <br />Response: SCC originally proposed the "Enkamat 7003" TRM, which was recommended by the manufacturers <br />representative, without the benefit of seeing the material. Upon receiving samples of the various types of TRM <br />available, SCC agrees with DRMS that the "Enkamat 7020" TRM is a better chojce for the proposed remediation <br />of the slide area. <br />Seneca Coal Company . P.O. Box 670 • Haydpp, Colorado 81639 <br />Telephone (970) 276707 • FAX (970) 276-3014 <br />