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' • <br />The Division therefore requests TCC submit a more comprehensive and detailed proposed <br />longwall subsidence monitoring program for the eastern end of Panel 12R. This program is <br />necessary to demonstrate that longwall-mining related subsidence in the Northern Mining <br />District occurs as predicted. <br />This program should include a proposed monument array pattern parallel and perpendicular to <br />the longitudinal axis of Panel 12R. This proposed array should contain a sufficient number of <br />monuments to accurately measure the full extent of the predicted effects oflongwall-related <br />subsidence (the maximum vertical subsidence deflection, the maximum horizontal extent of <br />subsidence effects at the surface, and the "angle of draw"). This array should additionally be <br />developed in a manner such that the two easternmost monuments, the two northernmost <br />monuments, and the two southernmost monuments from the center of Panel 12R would <br />experience no effect (horizontally or vertically) from subsidence of Panel 12R, so that these six <br />monuments may serve as "baseline" stations. <br />The. longwall subsidence monitoring program should include a description of how far (days, <br />weeks, months, etc) in advance of commencing the longwall in Panel 12R the monitoring will <br />begin, and should include detailed diagrams of the subsidence monitoring monuments <br />themselves. A discussion of how the monuments will be constructed and installed, so that they <br />will free from [he effects of soil freezing and thawing, should be included as well. <br />As a result of additional review of proposed exhibit 7f-1, the Division additionally requests <br />TCC to,describe the expected subsidence-related impacts to the County Road 33 culvert <br />situated immediately south of the source zone. This is the culvert that allows Foidel Creek to <br />flow from the north side of County Road 33 to the south side of the road. The Division <br />believes that at a minimum, the design gradient of the culvert will be reduced, consequently <br />changing the culvert's flow capacity. The potential for physical damage to [he culvert <br />(splitting) and to associated structures (headwall, anti-seep collars, etc) also exists. There <br />appears an additional potential for the fill compacted around the culvert to increase in <br />permeability, due to tension cracks potentially manifesting themselves within the fill. <br />Finally, please commit, with permit text, to immediately repairing any and all subsidence- <br />related damage to County Road 33 and the county road culvert. <br />19. This item has not been adequately addressed. <br />The Division's immediate concern regarding the undermining of the Twentymile Sandstone <br />outcrop near Count Road 33 is the protection of the health and safety of the persons using <br />County Road 33 who could be injured from a rock that could be dislodged from the source <br />zone. This concern is for potential rockfall that could occur relatively contemporaneous with <br />longwalling, as well as with rockfall that could occur months or even yeazs later. <br />Please provide a sentence for insertion into the permit that states that TCC guarantees that any <br />rocks dislodged from the source zone will not reach County Road 33. If TCC cannot provide <br />such a statement due to the uncertainty of the effects of subsidence on the outcrop, then TCC <br />