PERMFILE101131 - Laserfiche WebLink

Home Browse Search

Mountain Coal Company West Elk Mine RPE Shafts Project Plan lies between Sylvester Gulch and Box Canyon. At no time will water be allowed to collect at the head of the drilling pad. See TR-90, TR-79 and Exhibit 70, Volume IOB, and MR-303 for details on the runoff estimation and hydrologic analysis. Also attached is the SedCad analysis completed by Greystone Consultants that shows that the capacity of the RPE pond is large enough io contain the run-0ff associated with the 100 year 24 hour storm event and a SedCad analysis of the sizing of DCW 8A, DCW8B, and the culvert.. SHAFT AND MONITORING HOLE CONSTRUCTION This project is time sensitive. MCC is submitting this Technical Revision application in March of 2006, expecting that adequate time is allowed to obtain all necessary approvals of the proposed activities. Delays to the project could cause increased impacts due to winter construction or delays to West Elk Mine operations. MCC needs to construct the pad in sufficient time to perform the subsurface characterization investigations during the spring of 2006. The information gleaned from these investigations (estimated to require (r8 weeks of field work depending on the schedules of the contractors selected) will enable full design and construction bidding in advance of the 2006 construction season when RPE Shaft construction is currently planned and needed. The time for monitoring/emergency standby hole construction is estimated io be three weeks assuming springtime construction conditions. Later construction would delay shaft construction until the fall winter construction season The time for shaft constmction (2006 season) is estimated to be 3~ months as ,sir"-ing summertime construction conditions. Winter construction would lengthen the time to construct and will also cause increased impacts to the environment. To accommodate both the investigation (2006) and construction (2006) work, approval of the project is needed from the Division in March of 2006. The proposed monitoring/emergency standby hole construction technique utilizes gases (typically compressed air or nitrogen) to cool the drill bit and lift cuttings out of the wellbore, instead of the more conventional use of liquids. The advantages of air drilling are that it is usually much faster than drilling with liquids and it may eliminate lost circulation problems. The use of air drilling will not produce the drilling mud associated with water~irculated drilling therefore no mudpit will be required on the pad. All cuttings resulted from the drilling of the monitoring/emergency standby holes will be disposed of in the RPE pond The monitoring/emergency standby holes will be drilled 318 feet at 9 5/8-inches cased. As the anticipated shaft construction technique will be raise bore or raise bere/slashing for the RPE Shaft, cuttings from these construction activities will be disposed in the TR-105 Page 8 of 12