2016-05-19_PERMIT FILE - C1982056 (10)

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Twentymile Coal, LLC SOW — 9 East Bleeder Exhauster Borehole August 6, 2015 GENERAL SCOPE OF WORK Twentymile Coal (TC) will be installing two (2) boreholes as indicated on the attached mine drawing. One borehole will accommodate a 16" OD, schedule 80, weldable or T&C steel pipe. The second borehole will accommodate both a 6-5/8" OD and a 3.5" OD, schedule 80, weldable or T&C steel pipes. Each of the two boreholes shall include a 60' long, grouted surface conductor as needed. These boreholes will intersect the caved areas with rock rubble of the previously mined Wadge seam longwall panels as follows: 1. At this time, it is intended that the drill site will be accessed from the existing 18 Right access road — final site to be determined. 2. The site will be available for drilling on a 24-hour, 7 -day basis. 3. The drill sites will be permitted and prepared in advance by TC. 4. The site will have a level pad approximately 200' by 200' in top -of -pad size. 5. Each borehole shall include a 60' long, grouted surface conductor as needed. 6. The contractor shall provide the 60' of surface conductor casing that supports the drilling needs. 7. The drilling and supporting operations shall be monitored for methane at all times. 8. The approximate depths for each BH are as follows: a. 9 East Borehole Site: i. Surface elevation 6850' ii. Overburden depth to top of the Wadge seam 985' iii. Estimated top of coal elevation — Wadge seam 5865' iv. lnterburden Wadge seam to top of coal - Wolf Creek seam 155' v. Estimated top of coal - Wolf Creek elevation 5710' vi. Wolf Geek coal thickness 10' vii. Estimated bottom of coal - Wolf Creek elevation 5700' viii. Depth to coal floor— Wolf Creek seam 1150' 9. Borehole with both 6-5/8" OD and 3.5" OD, schedule 80, weldable or T&C steel pipes: a. Recommended method of drilling to minimize water inflow — flooded reverse drilling. b. This borehole will intersect the caved areas with rock rubble of the previously mined Wadge seam longwall panel at approximately 960' to 975' of drilling depth. A c. Drilling to the total depth of 1150' shall intersect the coal in an area that has not been underground mined. f� 0 d. Because of the possibility of the BH producing water, the surface casing for the 1st BH to be drilled should be oversized to approximately 24" OD as appropriate for the potential of drilling and reaming to a 22" diameter hole to accept a 16" OD schedule 40, weldable or T&C steel pipe to seal off the water. e. This first BH shall first be drilled to an approximate diameter of 13-3/4", hopefully to the full depth of 1150' without encountering significant water inflows. f. Should water not be encountered, the 6-5/8" OD and 3.5" OD, schedule 80, weldable or T&C steel pipes should be installed and grouted in place to a depth of approximately 1150. g. Sealing off water Option 1 — Should water be encountered — assume this to be at a depth of 700' for bidding purposes: i. In lieu of casing to seal off the water, spot a cement plug at the water inflow interval and drill out the cement plug. h. Sealing off water Option 2 - Should water be encountered and the Option 1 cement plug not seal off the water - assume this to be at a 700' depth for bidding purposes — the 13-3/4" hole should then be reamed to a 22" diameter to the 700' depth. i. A 16" OD, schedule 40, weldable or T&C steel casing would then be installed and grouted to seal of off the water. j. Assuming 700' of 16" OD, schedule 40, weldable or T&C steel pipe is installed and grouted to seal off the water, drill the remaining depth to the bottom of the Wolf Creek seam at an approximate diameter of 13-3/4". k. Install and grout off approximately 1150' of 6-5/8" OD and 3.5" OD, schedule 80, weldable or T&C steel pipe. 1. TC will provide all steel pipe except the surface casings. Bleeder Exhauster BH SOW 9 East 080615.doc Page 2