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Ms. Erich Crosbv Division ajMinerals and Ceoiogy September?1, 1999 Page ? Kauffman does not cut a trench around the entire perimeter of a mining phase prior to extracting the resource. The trench is cut along the perimeter as mining progresses from the lowest point (or the chosen point of dewatering dischazge) to the uppermost point in the mining phase. The active face of the excavation is generally perpendicular to the dewatering trench. Kauffman uses a backhoe to extract the resource from the top of the existing ground, working above and behind the active face. The dewatering trench usually extends 50 to 75 feet behind the active face. As mining progresses towazds the uppem~ost part of the phase, portions of the dewatering trench become progressively farther away from the active face. As backfilling is part of the reclamation of Phases I and II of this site, the dewatering trench will be backfilled at the same time as the rest of the interior of the pit (sequentially, following behind the mining). In Phase III, the dewatering trench will be backfilled as part of the liner construction. The applicant will be buying water from a private source to fill and replenish the reservoir as needed. For the initial filling, water will be pumped from the Boyd Lake Outlet Ditch into the reservoir. This is the same method as was used for the Kauffman's Stroh Pit. This was set up and approved by the local water commissioner. Afrer the initial filling, precipitation events will help keep the water level balanced. Water will not be discharged from this pond, other than from evaporation. As there are no physical inlet and outlet points for the reservoir, no features aze shown on the map. • The characterization of the limestone in terms of geotechnical properties is irrelevant to this application. The operator does not propose to use the limestone for any structural embankments that would be dependent on having a stable slope. The proposed backfilling would only bring ground elevations back up to historic levels with no embankments being created. Therefore, no testing has been done on this material. Samples of the limestone that we have would indicate that the material could be considered cohesionless and would probably have a friction angle ranging between 20° '~ and 25 °. ~ The width of the Boyd Lake Outlet Ditch, at the original ground elevation (prior to the creation of the limestone settling basins) vazies between an average of 80 to 100 feet. The depth of the ditch up to the original ground elevation (prior to the creation of the limestone settling basins) varies from approximately 12 feet on the north end where it Centers the mining permit, to approximately six feet on the south end where it exits this ermit boundary. The average distance that will sepazate the Boyd Lake Outlet Ditch from the reclaimed pond edge will be approximately 50 feet. Attached are two cross- sections which may help explain the relationship between the existing grades and the proposed post-mining grades at the Boyd Lake Outlet Ditch, and the rest of the perimeter of the old limestone settling basins.