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• proposed monitoring methods. ' This reconnaissance indicated that the geometry <br /> of the topography within the study area precluded the location of monuments <br /> for auto-areal triangulation outside of the actively subsiding mine area. As <br /> a consequence, the areal triangulation monuments would have to be surveyed <br /> each time the area was photographed. Once a survey party was in the monitoring <br /> area a survey of the subsidence monitoring net would be relatively simple. <br /> This factor, in conjunction with simpler monument construction for conventional <br /> surveying, resulted in the° selection of a conventional surveying approach for <br /> monitoring subsidence in the area instead of areal methods. <br /> The proposed instrumentation plan consists of three sub-tasks : <br /> 1. Establish surveying control in the monitoring area <br /> 2. Layout and installation of the subsidence monitoring net <br /> • 3. Monitor the subsidence net. <br /> Survey Control : <br /> No survey control presently exists in the subside.n:ce Tonitoring area <br /> because of its remote location. rt ,rill therefor_ be. necessary to bring <br /> coordinate and elevation control into the monitoring area fron the existing <br /> mine survey control net at No. 5 Mine. <br /> A closed traverse survey is proposed to establish control in the monitor- <br /> ing area. This survey will be performed with a Wild T-2 Theodolite and a Wild <br /> Distomat (Electronic Distance Measuring Device) . <br /> The control survey will require approximately six ridgetop control sta- <br /> tions to establish a point with known coordinates and elevation adjacent to, <br /> but outside of, the monitoring area. This control su:­ _ station :,i l l bc: <br /> • established in a location outside of any area that will be undermined during <br /> the duration of the research study. <br /> -8- <br />