PERMFILE63413 - Laserfiche WebLink

Home Browse Search

ties. It is possible that other equipment may also be used in the material excavation. Map E-1 shows • two cross-sections: A-A' and B-B', which are given in Appendix B. These cross-sections show that [he pit will be excavated to a 2H:1V slope to the bottom of the gravel. As this is being done, a trench around [he outside perimeter will always be dug deeper than the rest of the mine area. In this way, water from the mine area must seep through a sediment berm to get to the trench. A pump located in the trench will pump the water into the wetland, as shown on Map E-1. When the trench itself is be- ing excavated, a sediment berm will be created on either lateral side of the pump, therefore water from the trench must go through these berms to gel to the pump. All water discharge into the wet- land will be clean and will be regulated by a CDOH storm water/process water permit to discharge. Detail A, included in Appendix B, shows the locations of all berms around the pumping station. One pump will definitely be installed at the northwest corner of the mine area, and another may be used at the northeast corner, as shown on Map E-1. Once final depth is reached, the water will go through both sets of berms to get to the pump. A 2' thick gravel layer will also be left at the bottom of the pit. The gravel zone is approximately 16-20 feet thick, and volumetric computer analysis of the exist- ing and final topography shows a volume of 115,700 total cubic yards removed less 27,100 cubic yards of topsoil, yielding a total gravel volume to be mined of 88,600 cubic yards. This is equivalent l0 141,760 tons. These calculations are approximate since the exact extent of the gravel deposit in the field is unknown. The maximum annual mined tonnage rate for the pit is 69,500 tons, therefore, the mine area will last approximately 2.0 years, assuming the maximum rate is sold each year. The mining of the area will leave 2.OH:1.OV sideslopes on all final outside slopes down to the mining depth. In fact, during the mining process, the dozer will mine the deposit at a 2H:1 V slope, there- fore, the worst case bond calculations for reclamation will simply involve replacing topsoil, then seeding. It is possible, depending upon future demand, that the operator may request an expansion of this pit, requiring 112 permit status. No mining will be conducted at night and the majority of the material will be mined, crushed and sold in the spring, summer and fall months. There will be no fence around the operation, since it is well inside private property and there are no facilities on site. No problems are expected with van- dalism. Piceance Pit 7/01 14