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1999 Yoart Mim * 13-12 Draixare and Sedlmext CoxtrolPlon •7C <br />In select situations SCC may use TRMs as an alternative channel lining. Typical matting <br />construction consists of a three-dimensional corrugated matrix (with either coconut/straw or <br />polypropylene fiber) that will anchor and reinforce roots and stems for long-term stability. In <br />addition, the TRM deflects flowing water away from [he soil surface and increases surface <br />roughness. <br />TRM products that SCC may use at the Yoast Mine are manufactured by the following companies <br />(this is not an all inclusive list; if other products are available they may be utilized if they meet the <br />minimum design characteristics): <br />• American Excelsior Company <br />• Colbond Geosynthetics <br />• Greent-ix America <br />• North American Green <br />• Propex Geosynthetics <br />Channel stability was analyzed using the erodible channel sub-routine. The designs assume the <br />Tl2M is installed over bare soil. The channel roughness coefficient (i.e., Manning's n) and the <br />limiting velocity values were hand entered. Examples of manufacturer's published performance <br />values for select TRM products under bare soil conditions are summarized in Table 13-12.7, Turf <br />Reinforcement Mat Performance Guide. Manufacturer's performance specifications for these <br />products are found in Appendix 13-12.A, Turf Reinforcement Mat Design and Installation <br />Information. To calculate the greatest potential instability (i.e., the highest velocity) SCC selected <br />a roughness coefficient value of 0.023, which is less than any of the manufacturer's published <br />values. SCC selected 9.0 feet per second as the limiting velocity value. <br />Channel capacity was analyzed using the vegetated channel sub-routine. The channel roughness <br />coefficient is automatically calculated by the model. The limiting velocity values were hand <br />entered (manufacturer's published limiting velocity values for select TRM products are <br />summarized in Table 13-12.7. The designs assume a mixed grass community 11 - 24" tall, which <br />corresponds to a "B" retardance class, and results in a higher surface water elevation. <br />The postmine channels at Yoast Mine lined with TRMs will be either three (3) or ten (10) feet wide. <br />The minimum channel designs for the TRM lined channels also are summarized on the Figure 13- <br />12.3. SEDCAD4 demonstrations are presented in Appendix 13-12.3. <br />TRM installation will be in accordance with recommendations developed by the Erosion Control <br />Technical Council (ECTC, 2006) or the individual manufacturer's recommendations. <br />General installation steps are as follows: <br />1. Prepare a stable and firm soil surface free of large rocks and other obstructions. Apply <br />appropriate seed mixture. <br />2. Install TRMs after application of seed, mulches (if applicable) and other soil amendments, <br />unless soil in-filling is required. If soil in-filling is needed, install TRM, apply seed and <br />other amendments and brush or rake topsoil into TRM matrix. <br />3. Anchor top of blanket at end of channel section using trench and/or staples/stakes. <br />i <br />Montgomery fY/ahon Mixing Grauy * 165 S. Unimt Boulevard, Suite 460 * Znkavood, Ca(orada 80228 * (303f 763-5140 <br />TR-30 Revised 05/07 <br />