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<br />• <br /> <br />-35- <br />(1) The Thompson Ranch Buildings <br />(2) County Roads 92 and 115 <br />(3) The Dorchester Mine Waste Disposal Pile <br />(4) Fresh Water Pond !3 and Sediment Pond i4 <br />(5) Electric Power Substations fl and f2 <br />(6) Electric Transmissions Lines <br />(7) Telephone Communications Lines <br />(8) City of Florence Picnic and Recreation Area <br />(9) City of Florence Water Line <br />Dorchester Coal Company's subsidence inventory does not delineate any <br />renewable resource lands within the potentially affected area. <br />The applicant's subsidence survey contains a detailed projection of probable <br />and worst-case subsidence anticipated for each of the potentially affected <br />structures (see Tables 1.0 and 2.0 of Attachment E). These projections were <br />prepared in conformance with a prudent state-of-the-art of subsidence analysis <br />and prediction. Predicted probable maximum vertical subsidence ranges from <br />1.46 feet to 3.32 feet, and projected worst-case vertical subsidence ranges <br />between 1.46 feet and 6.48 feet. <br />Chapter 3.0 of Attachment E of the permit application presents proposed <br />subsidence control plans for each of the potentially effected structures <br />• within the permit area. <br />~~ The Thanpson Ranch was conveyed by deed from Cribbs-Jackson to members of the <br />Thompson family. Cribbs-Jackson also conveyed the mineral rights beneath that <br />property to Dorchester Coal Company, The Thompson Ranch Deed contains an <br />explicit waiver of all rights of surface support and relieves the grantors <br />from all liability from damage resulting from subsidence. The deed is <br />contained within Appendix C to Attachment E of the permit application <br />documents. This deed's waiver satisfies the requirement under Rule <br />4.20.3(2)(c) which addresses Surface Owner Protection. <br />The applicant's consultant, Rocky Mountain Geotechnical, Inc., projects <br />potential subsidence effects within Chapter 2.0 of Attachment E. The <br />consultant observes that retreat extraction of the submains underlying the <br />northern portion of the Dorchester refuse disposal pile could potentially <br />result in destabilization of that pi 1e. Rocky Mountain Geotechnical, Inc. <br />recommends that an additional subdrain be installed within the pile, in order <br />to preclude deterioration of the waste pile's mechanical stability. A <br />specific engineered plan for the installation of this drain is included within <br />the amended permit documents. <br />The mine plan contained within the amended permit application depicts boundary <br />pillars adjoining the permit area boundaries. The Division interprets ground <br />surface subsidence to constitute disturbance. All areas proposed to be <br />disturbed were included within the permitted area. (See Section 1 and <br />`~ stipulation 1) <br />