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<br /> <br />J. J. Dudash - 10 - January 17, 2007 <br />need to revise this map to comply with the stipulation noted in item <br />1. <br />BRL -The limited extraction zone lining the Hubbard Creek corridor <br />is defined by extending a safety zone a distance of one hundred <br />feet from the creek and then projecting a line down at the 25° angle <br />of draw to the coal seam. This is explained in Volume I, Page 108. <br />The line depicting the extent of subsidence based on the mine plan <br />accounts for the long term stability of the bleeder entry support <br />pillars. Calculations regarding the stability of these pillars is <br />presented in Volume III, Exhibit 15, page 18. This fine is developed <br />by projecting a 25° angle of draw from the unsupported mine <br />workings to the surface. Subsidence based on the mine plan <br />represents the maximum projected extent of subsidence and is the <br />most likely subsidence extent. <br />The line depicting the extent of subsidence without limited extraction <br />does not give consideration to support pillars. This line is <br />developed by projecting a 25° angle of draw from the perimeter of <br />the mine workings to the surface. This line does not represent the <br />extent of probable subsidence. <br />Map 27 presents the location of Dove Cave and its relationship to <br />the probable subsidence impact of mining. <br />c. Page 2.04-24. The reference to protecting Hubbard and Terror <br />Creeks states that the projected extent of subsidence would be <br />100-feet from the centerline of fhe creeks. As stated in item 1, the <br />stipulation of the federal coal lease requires that the zone of <br />protection be defined using a 25 degree angle of draw from the <br />centerline of the creek. This needs to be corrected and accurately <br />depicted on the appropriate maps. This section also needs to <br />discuss protection of Dove Gulch. <br />BRL -The term "projected extent of subsidence" means a 25 <br />degree angle of draw was projected from the mine workings to the <br />ground surface. BRL designed the mine workings to assure this <br />"projected extent of subsidence" was at least 100-feet from the <br />centerline of Hubbard and Terror Creeks. This is a more <br />conservative approach to protecting the creeks than required by the <br />federal coal lease stipulation. <br />Page 2.04-24. Bowie completed drill holes into the Mesa Verde <br />Formation during exploration drilling in summer 2000. This new <br />information should be used to update the permit. <br />