Laserfiche WebLink
Subsequent to the original submission of exhibit 3.4.8.A, the Division <br />addressed additional concerns to WECC regarding the possible effects of <br />subsidence upon landslide deposits neighboring Beaver and Minnesota <br />Reservoirs. WECC responded in letter form indicating that it desires <br />that the final designation of possible additional "safe areas" of <br />limited extraction be tied to the detailed results of the analysis <br />being performed upon the landslide deposit above the Town of Somerset. <br />In February of 1985, WECC submitted a permit revision application <br />requesting the addition of 1,630 acres to its permit area. This <br />revision application proposed the expansion of the mine plan, limited <br />to areas north of the Minnesota Creek surface and ground water divide. <br />In response to Division adequacy review comments, WECC clarified and <br />amended the original revision application mine plan, as shown on <br />Exhibit 3.4.4.6, to retain buffer zones to assure that no disturbance <br />would cross south of that divide. A 200-foot wide buffer was <br />delineated between development mined areas and the hydrologic divide, <br />and a 760-foot wide buffer between panels to be retreat mined and the <br />hydrologic divide. The Division finds, therefore, that the proposed <br />1,630 acre permit area increase will not affect areas south of the <br />Minnesota Creek surface water and ground water divide. Therefore, the <br />subsidence findings do not require any substantive amendment as a <br />result of the 1,630 acre permit area revision. <br />The Division finds that the following stipulations are necessary for a <br />findin of compliance with subsidence related requirements of Rule <br />2.05.66) and 4.20. <br />Stipulation No. 13: THE DIVISION DIRECTS WECC TO COMPLETE THE <br />INSTALLATION OF THE SUBSIDENCE MONITORING NETWORK PRIOR TO THE <br />INITIATION OF EXTRACTION OF COAL WITHIN THE PANEL DESIGNATED IN <br />APPENDIX A TO THE NOVEMBER, 1984 PERMIT REVISION APPLICATION ENTITLED <br />"APPLICATION TO REVISE THE MINING AND RECLAMATION PLAN FOR THE MT. <br />GUNNISON N0. 1 UNDERGROUND MIryE". THIS MONITORING NETWORK IS DESIGNED <br />TO MONITOR THE FIRST PANEL WEST FROM THE SW MAINS INTAKES AND SOUTH OF <br />THE NO. 1 WEST SUBMAINS, DESIGNATED AS "PANEL 1W-1S", LOCATED ADJACENT <br />TO AND PARALLEL TO THE WESTERN BOUNDARY OF SECTION 21, RANGE 90W, <br />TOWNSHIP 135. THIS MONITORING NETWORK SHALL CONSIST OF SUBSTANTIAL <br />MONUMENTS DESIGNED TO RESIST FROST-HEAVE, FIRE, AND THE ACTIONS OF <br />CATTLE AND WILDLIFE. <br />Stipulation No. 14: THE SUBSIDENCE MONITORING NETWORK SHALL BE <br />SURVEYED UTILIZING CONVENTIONAL GROUND SURVEYING TECHNIQUES, DESIGNED <br />TO ACHIEVE HORIZONTAL ACCURACIES COMPLYING WITH THE U.S. DEPARTMENT OF <br />COMMERCE'S "SECOND ORDER, CLASS II" SURVEY STANDARDS, AND VERTICAL <br />ACCURACIES NO LESS THAN + 0.2 FEET. THIS GRID SHALL BE SURVEYED TWICE <br />PRIOR TO THE INITIATION OF SUBSIDENCE. IN CONJUNCTION WITH THESE <br />SURVEYS WECCC SHALL SELECT AND ESTABLISH A MINIMUM OF SIX TRIANGULATION <br />BENCH MARK MONUMENTS OUTSIDE THE AREA OF ANTICIPATED SUBSIDENCE <br />EFFECTS, FOR THE PURPOSE OF CORRELATION WITH AERIAL PHOTOGRAMMETRIC <br />POST-SUBSIDENCE SURVEYS. <br />