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-3- Further, the waste disposal pile will be constructed with granular underdrains, designed to prevent saturation or invasion of water into the waste pile. These five underdrains have been appropriately sized to ensure that the pile will not become saturated. West Elk Coal Company proposes to monitor both the ground water saturation beneath and within the pile, in order to ensure that the pile remains dry. The operator also agreed to install several survey monuments to monitor slope stability of the completed structure and adjoining areas. The original permit includes a statement of intended possible secondary mining of coal beneath the coal pile. In order to assure the assumptions made in completing the stability analysis are correct, the Division believes it appropriate to impose the following stipulation upon approval of this permit revision. Stipulation No. THE DIVISION DIRECTS WEST ELK COAL COMPANY, PRIOR TO ANY DISTURBANCE AT THE WASTE PILE SITE, TO SUBMIT AN APPROPRIATE AMENDMENT TO THE OPERATION PLAN WITHIN THE EXISTING PERMIT TO LIMIT EXTRACTION BENEATH THE WASTE PILE TO PRIMARY DEVELOPMENT ONLY. NO SECONDARY EXTRACTION SHALL BE ALLOWED BENEATH THE PILE OR THE IMMEDIATELY ADJOINING AREA. During the past several years slope instability has occurred in the surficial deposits above the portals of the Mt. Gunnison No. 1 Mine. The area effected lies downslope from the toe of the proposed pile. Because of this evidence of surficial instability adjoining the proposed pile area, the Division desires additional surface monument at ion and stability monitoring. For this reason, the Division believes it appropriate to impose the following stipulation upon approval of the permit revision application. Stipulation No. THE DIVISION DIRECTS WEST ELK COAL COMPANY, PRIOR TO ANY DISTURBANCE AT THE UPPER WASTE SITE, TO INSTALL SEVERAL ELECTRONIC TILT METER TUBES DOWNSLOPE FROM THE TOE OF THE PROPOSED WASTE STRUCTURE. WITHIN 30 DAYS FOLLOWING APPROVAL OF PERMIT REVISION APPLICATION, WEST ELK COAL COMPANY SHALL SUBMIT TO THE DIVISION A PLAN FOR THE INSTALLATION OF THE TILT METER FACILITIES. THESE TILT METER INSTALLATIONS SHALL OCCUR IN THE VICINITY OF MONUMENTS S1 AND S2, AS INDICATED ON DRAWING N0. MG-R C-001, INCLUDED IN THE PERMIT REVISION APPLICATION. DURING THE INSTALLATION OF THESE TILT METER TUBES, THE OPERATOR SHALL AUGER AND LOG THE SURFICIAL AND BEDROCK STATIGRAPHY ENCOUNTERED. AUGERING SHALL CONTINUE UNTIL THE OPERATOR HAS ESTABLISHED INTACT BEDROCK OCCURRENCE. IF ANY EVIDENCE OF EXISTING LANDSLIDE DEPOSITS IS ENCOUNTERED, THE OPERATOR SHALL DEFINE THE NATURE AND EXTENT OF THE PRE-EXISTING SLOPE INSTABILITY. IF SUCH LANDSLIDE ACTIVITY IS DISCERNED, THE OPERATOR WILL BE REQUIRED TO APPROPRIATELY RECONFIGURE THE PILE DESIGN, PRIOR TO INITIATION OF ANY CONSTRUCTION ACTIVITY.