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• B. With the submittal of Permit Revision No. 2, the Division determined that Bear Coal Company should submit a list of the various sttucturrs and renewable within and adjacent to their permit area. Bear Coal responded by supplying this list of structures (T'able 15). Based on this information, the operator submitted a subsidence control play (page 2.05-63d of the permlit application) to restrict mining and associated subsidence to areas that are well away from structures or renewable resource lands absent additional subsidence. monitoring. However, upon further review, the Division has determined that additional subsidence monitoring may be required in areas that were previously not considered as renewable resources and have not been identified as such by the operator. These auras are the Mountain Coal ventilation fan access road, an ephemeral surface tributary to Lone Pine Gulch, and the area overlying panels 31-38 if accurate predictions cannot be extrapolated for this aura. This additional monitoring will be addressed through submittal of a technical revision as required by Stipulation No. 35, which is as follows: Stipulation 35: THE OPERATOR SHALL SUBMIT A TECHNICAL REVLSION WHICH WILL ADDRESS THE LSSUE OF ADDITIONAL SUBSIDENCE MONITORING FOR PANELS 19-23, 24-30, AND 31-38 PRIOR TO THE ONSET OF MINING THPSE AREAS BUT NO LATER THAN JUNE 1, 1995. • Bear Coal Company has backf-illed the portals at the Bear No. 1 and 2 Mines. The Division stipulated that the stability of these two backfilled areas be monitored for a period of two years in the September 18, 1985 permit revision fmdings document. This stipulation has been satisfied. The canyon walls of the North Fork of the Gumison River are covered with numerous landslide deposits. These mass movement features vary in age from ancient to modem. Rotational slumps, translational, earthflow and debris-flow features are present on the site. A study conducted by Rocky Mountain Geotechnical of the Bear No. 3 pmperty has mapped numerous mass movement features. The Division has been concerned about reactivation of these features by subsidence of the land surface resulting from coal extraction. An extensive study by Rocky Mountain Geotechnical was completed in 1986 that addressed the relationship between subsidence and the potential reactivation of slide bodies above the Bear No. 3 Mine. The study concluded that the general mass movement mechanism was small, shallow slope failures rather than large, deep failures. The report concluded that the Lwdslide features above the Bear No. 3 Mine are currently unstable and that failures will occur regardless of subsidence effects. No subsidence effects are expected to occur in the critical tce area of • any of the slide bodies. Subsidence in these areas will be controlled by split pillar removal. 31