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<br />Twentymile Coal Company must provide a plan to ensure that rockfall will not present any hazard to <br />public health and safety. [f there is several month delay between undermining and potential rock <br />failure, how will Twentymile know when to close the road? Please provide evidence that Routt <br />County approves of County Road No. 33 closures. Please, also provide greater detail to how TCC <br />will protect public health and safety with regard to the undermining of the Twentymile sandstone <br />outcrop adjacent to Routt County Road No. 33. [f Twentymile Coal Company cannot assure that no <br />risk to the public would be likely, then additional protection of the roadway may be necessary. <br />20. Exhibit 7F-1 makes recommendations regarding protection of public health and safety of County <br />Road No. 33. Exhibit 7F-1 recommends removal of loose rock over longwall panel 12R prior to <br />undermining. Please commit to removal of loose rock in the permit text. <br />21. Exhibit 7F-1 did not address potential rockfall due to weathering (freeze-thaw cycles) of blocks that <br />may be loosened due to subsidence of longwall panel 12R.. Please address the potential for impacts <br />due to weathering of loosened blocks of the Twentymile sandstone located adjacent to Routt County <br />Road No. 33. Please provide a plan to assure that falling rocks will not jeopazdize public health and <br />safety. <br />22. Please clarify the mitigation plan for Routt County Road No. 33 over panel 12R in accordance with <br />Rule 2.05.6(6)(f)(iv). <br />23. a) Revised page 2.0~-181.6 (rev.8/27/99): The description of the permit term should agree with that <br />of RN-03 (1998-2003). ~~ <br />b) Revised page 2.05-181.6 (rev. 8/27/99): The description of potential impacts to the east-west <br />powerline north of 18R gateroad needs to clazify that the powerline is outside predicted angle of <br />draw from longwall panel 16R. <br />c) On this same page, the overburden depth in the locality of the rail line is described as 100 feet to <br />1400 feet thick over the mine workings. The Division questions if the 100 foot thickness value is <br />correct. Cross sectional maps do not suppoR this thin an overburden measurement. Please correct <br />this reference. ~~ <br />2 . Revised page 2.05-] 81.6 (rev. 8/27/99) references Exhibit 7e-3N "Northern Mining District AVF <br />Subsidence Prediction" The Division is not in receipt of an Exhibit 7e-3n or 7e-3. The Division is <br />unable to complete review of the subsidence impacts without the correct Exhibit. Please submit the <br />exhibit. If this exhibit been submitted under a different name, please indicate the name of the exhibit. <br />25. In the subsidence impacts section, revised page 2.05-181.6-181.7, the predicted subsidence to Foidel <br />Creek is 0-46 inches over longwall panel 12R. However, the adjacent longwall panel, 9R in the EMD <br />had subsidence of 43-86 inches. Please provide detail concerning this significantly reduced subsidence <br />prediction between the two adjacent longwall panels. ~ ~ < <•~ ~•~ ~ C K <br />26. Revised page 2.05-181.8 (rev. 2/24/99) states, "The projected impacts to the creek are presented in <br />Exhibit 7E-l, Northern Mining District Subsidence." Exhibit 7E-l, page 6, states, "Impacts to Fish <br />Creek and its AVF have been evaluated in a separate report." There is no reference to where this <br />C:/jhb/CS?056/PROS/jhb adq I .doc 4 3/10/00 <br />