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Permit Revision Adequacy <br />July 6, 2004 <br />Page 14 of 1 S <br />recommended that geophones be installed to monitor at both the north and south abutment of <br />the Monument Dam. Such monitoring would begin as soon as mining starts in the 2"d panel to <br />the north, continue through the first, and commence again and end with mining in panel E-9. <br />The purpose of this monitoring is to demonstrate that the seismic values used to determine <br />stability of the Monument Dam aze not exceeded as mining approached the stmcture. The <br />monuments across the dam and the seismic geophones should be established before and <br />monitored during mining of the panels in sections 33 and 34 to establish the local response. A <br />subsidence report on subsidence phenomena associated with the northern panel should be <br />provided to the Division before longwall extraction of the panel closer to the Minnesota <br />Reservoir that demonstrates the accuracy of predictions. <br />The Division further recommends that the centerline of the Monument Dam embankment be <br />described in accordance with Rule 2.05.6(6)(c)(i)(C). <br />103. The application contains good descriptions of ground movement, slides and rockfalls and some <br />information on seismic impacts. That section (pages 2.05-100, ] O1) would be a good place to <br />add information on seismic impacts. The size of seismic events, including the maximum <br />probable event, from a subsidence within the mine could be defined. From any such epicenter, <br />isoseismic lines could be drawn based on the lithology of the area for any panel closest to a <br />tazget feature. <br />104. Regarding the reporting schedule, page 2.04-124, the Division requests that the condition be <br />added that if an anomaly is experienced that diverges from the predictions, the Division will be <br />notified within three days. Further the Division requests that monitoring of the north panel be <br />submitted to the Division prior to initiation of mining of the southern panel. <br />105. On page 2.05-112, the seismic effects on the Minnesota Reservoir need to be quantified (as <br />noted above) and the relationship between strain and percent needs to be clarified. <br />106. A map showing existing subsidence features within the permit area (Rule 2.05.6(6)(e)(i)(F)(I) <br />needs to be added to the PAP. This should include landslide locations identified on page 2.05- <br />97 and any surface rockfalls thought to have resulted from longwall mining. <br />107. Rule 2.05.6(6)(e)(i)(F)(III) requires a map displaying the surface areal extent of the area <br />determined by the projected angle-of--draw. Please add this to the PAP. Such a map should <br />include rockfall azeas, slide areas and isoseismic lines as per 2.05.6(6)(e)(i)(F)(IV). <br />108. The Division requests that monitoring to determine commencement and degree of subsidence <br />be added to the proposed plan for the vicinity of the Minnesota Reservoir in compliance with <br />Rule 2.05.6(6)(f)(iii)(C)(V). <br />109. The Division has several suggestions regazding measures to be taken to mitigate the effects of <br />material damage or diminution of value or foreseeable use of lands (Rule 2.05.6(6)(iv). MCC <br />proposes to monitor roads monthly and to clear rockfalls or damage, and post signage, the <br />Division suggests the signage proposal be expanded to include example wording, and that the <br />posting period be better defined. For example, the signs could go up approximately a month <br />