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The predicted surface subsidence is not expected to significantly <br />• impact slope stability on the front slope of Coal Ridge. This <br />conclusion is based on: <br />o the generally strong nature of the overburden strata; <br />o the thickness of the overburden between the mining horizon and <br />the surface (Figure 3.3-9); <br />o the paucity of "daylighted" structures within the range of <br />naturally occurring slope orientations; <br />o the poorly developed nature of the 29NE-dipping joint set <br />which is the only "daylighted" structure; <br />o the overall stability of existing and man-made slopes within <br />and adjacent to the proposed mining area; and <br />o the overall stability of existing slopes above previously <br />undermined areas. <br />A limited monitoring program consisting of installed monitoring <br />points and observations of the surface is proposed. A monitoring <br />line will be positioned above the area where the maximum antici- <br />pated open span should occur as a result of the five-year mining <br />• plan. During surveys of the monitoring line, NCIG proposes to make <br />observations of the surface to determine the existence, development <br />and magnitude of surface cracking, should it occur. The surface <br />area above the mine is remote, inaccessible, and subject to heavy <br />snow accumulations during the winter. Access is difficult and time <br />consuming under the best of conditions. The location of the <br />monitoring line, as well as the installation and monitoring <br />schedules, will be a function of weather conditions, site access- <br />ibility, and mining schedules. <br />Proposed mitigation measures are presented in the unlikely event <br />that sinkhole subsidence or slope instability develops. <br />• NCIG - Coal Ridge #1 4-91 ABC/1145/910509 <br />-rR-7 <br />