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GENERAL42877
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Last modified
8/24/2016 8:11:40 PM
Creation date
11/23/2007 12:02:47 PM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
C1980007
IBM Index Class Name
General Documents
Doc Date
3/11/2002
Doc Name
EA Coal Methane Drainage Project -Panels 16-24
From
MWH for USDA Forest Service
To
DMG
Permit Index Doc Type
General Correspondence
Media Type
D
Archive
No
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Coal Methane Drainave Proied - Panek 1G-24 Wu/ E!k Mine <br />7-8 ' <br />1.3.6 Operate the MDWs to Drain Methane from the Underground Mine Workings , <br />Following completion of each MDW, a methane exhauster would be installed to draw the methane to <br />the surface where it would be used to power the exhauster blower unit, with any excess vented to the <br />atmosphere. Bottled propane would be used as a back-up fuel source for exhausters if methane <br />concentrations are too low to power the exhauster units. The MDWs would be used in combination <br />with the existing mine ventilation system and horizontal methane drains within the underground mine <br />workings to effectively reduce and control methane levels is active underground mining areas. <br />Exhauster units are self-contained skid- and tire-mounted units. These units would be MSHA <br />approved for safety, would 6e inspected on a regulaz basis, and would be enclosed within a security <br />Eence. Methane exhausters would remain in-place and continue to operate so long as they continue to <br />be effective in draining methane from the underground mine workings. Based on recent MDW <br />experience, it is anticipated that each MDW would remain active and continue to be effective during <br />the period when the coal extraction face approaches it, passes underneath it, and for a period of time <br />after it passes beyond it. Experience with existing MDWs indicates that some wells continue to vent <br />methane for several months after the extraction face has passed by. 1t is currently anticipated that the <br />effective life of MDWs would range from six months to two yeazs. MDWs in one panel may prove <br />effective in venting methane from adjacent mining panels. <br />MCC would monitor and inspect active MDW installations daily following initial installation to assure <br />that they are functioning properly. Monitoring would focus on evaluating the rate of methane <br />production and the constituents of the exhaust gas and would involve collection of gas samples. <br />Inspection would involve checking the MDW installations and methane exhausters to assure that they <br />are functioning properly and to identify any pzoblems or concerns. It is anticipated that the <br />frequenry of monitoring would decrease to weekly monitoring, as required by MSHA. Inspections, <br />to assure proper operation, would be more frequent and could vary seasonally. MCC is testing <br />remote sensing equipment that could reduce required monitoring and inspection frequency, if proven <br />consistently reliable. Access by ATV and/or pick-up, and snowcat or snowmobile in the winter, for <br />at least weekly monitoring would be needed for the life of the MDWs, estimated at this time to be six <br />months to two years. It is anticipated that all active MDWs would be inspected and monitored in one <br />weekly trip. <br />1.3.7 Plug and Seal MDWs and Exploration Drillholes and Reclaim Associated <br />Disturbance <br />Once the MDWs on each pad aze no longer needed, the methane exhauster units would be removed, <br />the MDWs would be plugged and sealed, and remaining pad areas and associated new access road <br />disturbance would be reclaimed. MDWs and exploration drillholes would be plugged, sealed, and <br />abandoned consistent with applicable CDMG permit and BLM lease requirements. Sealing and <br />plugging would involve placement of cement from the hole bottom or from a plug set near the end of <br />the casing to 50 feet above the uppermost thick coal seam and from 50 feet below to 50 feet above <br />any aquifers encountered in the hole. The remainder of the hole would be filled with an approved <br />completion mud, gel, cuttings, or cement to within 5 feet of the surface. A 5-foot cement surface <br />plug would be set, and an appropriately labeled monument marker would be cemented into the <br />surface plug. Surface casing would be cut off at the level of the soil surface and would be covered <br />during regrading. <br />Drill pads and MDW operating pads would be reclaimed by draining, backfilling, and compacting the <br />fill in the mud pits; cleaning up and removing any trash, debris, and drilling materials and supplies; <br />returning the disturbed areas to their approximate original contour; replacing salvaged soft materials; <br />and revegetating the disturbed azeas. As indicated by Tables T1A and TIB there would be three <br />options for decommissioning of new road disturbance; the road would be obliterated by pulling any <br />cut material back onto the road and returning disturbed areas to their approximate original contour; <br />EnviroxmentalA.creument <br />~3'.iGP/nL..rm CdGlE.nunyr l/S/a'fi IrJF'r <br />S/S/OI/ <br />
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