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Potential damage to powerlines in areas of retreat mining can be mitigated by <br />measures conducted both prior to coal extraction and following initial subsidence. <br />Measures which may be conducted prior to coal extraction include reduction of <br />line tension to allow for anticipated elongation of lines within affected areas. <br />Mitigation measures which can be most effective following initial subsidence <br />include re- tensioning lines and /or raising or straightening powerpoles where <br />subsidence has reduced powerline clearances. These measures are commonly <br />utilized and have proven effective in underground mining areas in the eastern <br />portion of the United States. Ongoing monitoring enabled more accurate <br />prediction of the location of potential extension /compression strains, allowing for <br />timely mitigative actions. Subsidence did not result in any significant adverse <br />powerline impacts, so no mitigation was necessary and most of the potentially <br />affected powerlines have now been removed. <br />The Florence waterline was reconstructed and partially relocated in 1994. Repairs <br />focused on replacement of deteriorated clay pipe with more flexible PVC pipe. <br />Relocation involved eliminating certain high maintenance elevated and gradient <br />sections and shifting overall alignment to avoid areas with extensive abandoned <br />underground mine workings. The new alignment of the waterline resulted in <br />abandonment of the section of waterline corresponding to Monuments G, H, and <br />I. <br />EFCI conducted room and pillar mining operations in the vicinity of the waterline <br />as indicated on the Mine Plan Map, (Map 17). Because of the depth of the coal, <br />surface subsidence effects are realistically expected to be minimal. No barrier <br />pillars or other special modifications in mining techniques are considered <br />necessary. Specific monitoring measures have been implemented and will <br />continue so long as necessary to insure protection of the waterline. The eight (8) <br />subsidence monitoring monuments depicted on the Mine Plan Map (Map 17) have <br />been monitored quarterly to identify the location, nature, and magnitude of <br />subsidence which could potentially impact the waterline. <br />MR -52 2.05.6 -65 Revised — July 2003 <br />