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RULE 2 - PERMITS <br />• Little Grassy Creek and the 69 KV power line are located near the portal area and at depths <br />of 200 to 400 feet. These structures would be most susceptible to damage if subsidence were <br />to occur. These structures are under the main entries that are designed for long term stability <br />or under continuous miner development sections that are also designed with stable pillars. At <br />these low depths, pillar failure, or pillar punching will not occur, because of the strong roof <br />and floor strata. The only failure that could cause any reaction at the surface, is roof failure <br />that would have a chimney effect all the way to the surface. The immediate roof has . both a <br />strong "B sandstone" and strong "C sandstone" member which would form a compression <br />arch with failure of the immediate roof. A fault or two parallel faults would have to be <br />intersected to cause a failure to the surface. With this failure, the material falling from the <br />roof would have a bulking or swelling effect during failure and become self supporting, <br />resulting in very little reaction at the surface and therefore no material damage or diminution <br />of the structures. No faults have been identified in the portal area or in areas of shallow <br />overburden near Little Grassy Creek or the 69 KV power line. <br />This prediction is supported by the reference in Exhibit 2.05.6 -E2, What is Mine <br />Subsidence, as follows: <br />'Room and pillar mining is generally less disruptive to nearby surface waters than <br />high- extraction methods. Individual openings have only minimal localized draining <br />impacts due to self - supporting roof members which span the opening forming a <br />compression arch, with the support pillars serving as abutments. This `pressure arch' <br />limits not only the deformational, but also the hydraulic influence of the opening <br />• (Booth, 1986)" <br />Map 2.04.3 —M1, Land Use, shows that existing land uses are rangeland/wildlife habitat, and <br />postmine land uses are also rangeland/wildlife habitat, neither of which is considered <br />pastureland. Map 2.04.10 -M1, Vegetation — Permit Area, shows the vegetation is <br />sagebrush/grassland, rock outcrop, mesic drainage riparian, and sagebrush/mountain brush <br />mosaic. This vegetation is not associated with prime farmlands or pastureland. There are no <br />structures located within the area covered under the initial permit term that would require a <br />pre- mining survey. As documented in the discussion of Probable Hydrologic Consequences, <br />it is not anticipated that any significant impacts on any water supply sources or aquifers will <br />occur as a consequence of mining and related activities under permit approvals for the initial <br />permit term. <br />Section 2.05.6(6)(b)(ii) requires a monitoring program, if the Division concurs with the <br />conclusions of this prediction of subsidence consequences. In lieu of the monuments <br />required in (c) of this section, PSCM proposes that the monitoring program be an inspection <br />of the underground workings and a report. Monuments on the surface will only measure the <br />effects of subsidence after failures occurs. The design of the openings and the pillars at <br />PSCM make this unlikely. Inspection of the underground works will predict the likelihood <br />of subsidence from faults or roof or pillar failure prior to the subsidence occurring. <br />Twelve premining survey monuments, in the form of PK nails, will be located on the edge of <br />• Routt County Road 27. Three monuments will span each set of entries passing beneath the <br />PSCM Permit App. 2.05 -104 Revision 04/19/10 <br />