2015-06-15_REVISION - C1980007 (2)

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Welt, Kathy From: Welt, Kathy Sent: Monday, June 15, 2015 3:48 PM To: Welt, Kathy Subject: Upper Poison Gulch Road Stabilization From: Peacock, Michael J. Sent: Monday, June 15, 2015 3:37 PM To: Dan Gray (degray@fs.fed.us) Cc: Norris, Weston; Welt, Kathy Subject: Upper Poison Gulch Road Improvements Dan, Per our discussion this afternoon, this email is to confirm our agreed planned stabilization of the boggy portion of the road between the turnoff to E5-15 and the turnoff to E6-12. There is approximately 450 feet of the current road that is underlain by up to 8' of topsoil in two places that are approximately 150' and 300' in length separated by a mound approximately 150' long of good subgrade material. Mountain Coal Company proposes to improve both the road and the drainage through this area at the same time to provide a long-term solution to the soft ground as this road will be utilized for panel 6 and panel 7 Mine vent boreholes and will need to remain in service approximately 4 years. The plan will consist of the following key items: • Excavate and clean the drainage ditch on the west side of the current road so that it will properly drain the swale just beyond the E5-15 turnout. • Clean the Swale of debris and upgrade the drainage through it. • Excavate the topsoil approximately 3' below the current road surface and install 4"x6" rock crossdrains (approximately 3'x3', quantity -three) wrapped in non -woven geo-textile to drain into the drainage along the west side of the road. Excavated topsoil is to be placed in a pile on the turnout to E6-12, identified as "topsoil" and protected from dilution and contamination by erosion controls. Install 16" culvert between the last crossdrain and the turnout to E6-12 to provide adequate drainage from the upper basin. Install a drainage ditch (approximately 3' wide by 1 %z' )from this point along the west side of the road to the top of hill extending behind the turnout to E6-12 to provide drainage for all sheet flow from the east facing slopes along the road. • Install a layer of non -woven geotextile over the remaining soft sub -grade and corduroy aspen logs perpendicular with the run of the road . The logs are readily available in the adjacent area. Both good quality deadfall and salvaged trees will mal<e-up the corduroy materials used. • Key in the aspen corduroy with 3" road base and cover with another layer of geotextile • Spread a minimum of 6" of 1 %" road base over the geotextile and surface the road to a finished width of 12' and a final grade approximately 12-18 inches above the adjacent soils. Michael J. Peacock, P.E. Mine Projects Engineer Mountain Coal Company P.O. BOX 591 Somerset, Colorado 81434 moeacockaarchcoal.com Ph. 970-929-2301