Laserfiche WebLink
<br />Stipulation No. 3: <br />PRIOR TO MINING IN THE MOFFAT AREA, THE APPLICANT SHALL DEMONSTRATE, BASED <br />UPON ON-THE-GROUND PERFORMANCE, THAT THE CONVEX LOWER SLOPES DO NOT CAUSE <br />EXCESSIVE RILLING AND GULLYING OR THAT RILLING AND GULLYING ON THESE SLOPES <br />CAN BE CONTROLLED. IF THE APPLICANT'S EFFORTS TO CONTROL RILLING AND GULLYING <br />IN THE AREAS RECLAIMED PROVE UNSUCCESSFUL, THE APPLICANT WILL REDESIGN THE <br />POST-MINING TOPOGRAPHY TO ELIMINATE THE CONVEXITY FROM THE LOWER PORTIONS OF <br />THE SLOPE. <br />A concern addressed during the previous permit term pertained to back filling <br />and grading of spoil ridges during the winter months. Pittsburg and Midway <br />stated that the risk of subsidence within the spoil ridges increased when the <br />spoil was graded into valleys containing drifted snow pack. To reduce this <br />subsidence risk, a minor revision submitted by Pittsburg and Midway was <br />approved by the Division on June 28, 1985. This revision allows, under <br />certain winter conditions, the delay in complete leveling of the spoil <br />ridges. This delay may allow four (4) or more spoil ridges to be left behind <br />the active pit. However, any spoil ridge which accumulates after the fourth <br />(4) ridge and/or 180 day time limit following coal removal, will be rough <br />graded at least to the depth of one (1) dozer blade. The total spoil ridge <br />volume will never be greater than the total of four (4) spoil ridges for the <br />length of pit as calculated for the bond. Final grading to the approved <br />post-mining topography will be del dyed until the spoil valleys thaw but <br />grading to within the required four (4) spoil ridges of the active pit will be <br />completed by June 1st. Pittsburg and Midway will notify the Division prior to <br />implementation of this plan. <br />During the previous permit term, a portion of the reclaimed slope at the South <br />of Shop Area at the Edna Mine failed. Approximately one hundred (100) acres <br />were disturbed by this landslide. <br />The South of Shop Area, which is within the approved permit area <br />(Exhibit 1.0-1, revised April, 1986), was mined during the period July 1976 <br />through August 3, 1977 (Exhibit 3.1-2, revised April, 1986). Reclamation <br />activities occurred in 1978. <br />Pittsburg and Midway has conducted an investigation of the failed slope. The <br />mechanisms of failure, however, have yet to be adequately addressed. It is <br />hypothesized by Pittsburg and Midway that the cause of the failure is related <br />to excessive pore-water pressure, local geologic characteristics, as well as <br />mining and reclamation techniques. <br />At this time, the permittee remains responsible for reclaiming the area <br />disturbed by the slide to the standards of the Colorado Mined Land Reclamation <br />Board Interim Program Standards. The Colorado Mined Land Reclamation Board in <br />an Order dated September 27, ]984, expressly reserved its authority to require <br />Pittsburg and Midway to provide additional performance warranties and to <br />perform such reclamation activities as the Board deems appropriate. <br />As the reclamation activities specified in the approved mining and reclamation <br />plan do not include the reclamation of the South of Shop slide, Pittsburg and <br />Midway has committed to submitting a reclamation plan for this area prior to <br />February 15, 1988. This plan will also include the approximate cost of <br />reclamation for the South of Shop Area. <br />-40- January 13, 1988 <br />