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<br />• ~1pyt6r.e~- EXB:IBTT D <br />MINING PLAN <br />Section 1-Description of Methods <br />Western Mobile Northern, Inc., a subsidiary of Lafarge Corporation, proposes to extract <br />sand and gravel from a site currently used as agricultural and pastureland. The site is <br />located on Larimer County Road 19, between the Cache La Poudre River and U.S. <br />Highway 287. Western Mobile Northern Inc. owns this parcel of land. Western Mobile <br />Northern, Inc. (hereafter referred to as Western Mobile) currently operates a gravel <br />extraction, processing, stockpiling and distribution yard just south of the proposed sight, <br />under the DMG permit #M 77-439. Work will proceed in two phases removing a total of <br />approximately 1,400,000 tons of sand and gravel. This will be done at a rate of between <br />200,000 and 800,000 tons per year, resulting in a time span of 3-7 years for completion of <br />mining and reclamation. <br />The methods used for this operation will be consistent with dry, open pit mining. Phase <br />will consist of digging a one hundred foot wide dewatering trench around the perimeter <br />of the pit. Two settling ponds will be created along the east side of the pit, as shown in <br />Exhibit C. Water will be pumped into the ponds, gravity flow from the ponds into the <br />existing dewatering trench of the neighboring extraction site (#M 77-439), and pumped <br />as needed into the Cache La Poudre River at the same discharge point as the existing <br />operation. The conveyance from the settling pond to the existing dewatering trench will <br />consist of a weir from the pond and an open trench/channel conveyance. For the <br />estimated 3 cfs maximum pumped flow, this conveyance should not be larger than 1.5 <br />feet deep (including freeboard) at 3:1 sideslopes. Erosion control such as riprap Lnay be <br />provided as needed, however hydraulic calculations indicate non-erosive velocities even <br />at relatively steep slopes. All necessary NPDES-type permits will be acquired prior to <br />discharge. Sediment trapped in the settling pond will be removed as needed and used for <br />reclamation. <br />Overburden materials (topsoil, sandy silty clay, sandy silt, and silty sand) will be used to <br />create temporary landscaping berms along the County Road 19 frontage. These berms <br />will be approximately 6-7 feet in height and be removed during the reclamation process. <br />Remaining overburden will be stockpiled around the perimeter of the pit. Topsoil will be <br />segregated from remaining overburden either in a separate stockpile or at one location in <br />a overburden stockpile, except where used in the temporary berm as growth medium. A <br />conveyor may be constructed to transport resource to an existing conveyor that crosses <br />the Cache La Poudre River. Material may also be transported across the river by a low- <br />water crossing. Both the low-water crossing and conveyor routes are entirely within the <br />affected land areas of Permit #77-439. Primary rushing will occur on the pit floor. <br />Material will then be transported to the existing operation to the south of the Cache La <br />Poudre River for secondary processing, washing and stockpiling. Material may be <br />stockpiled at the adjacent operation south of the river. <br />Phase 2 will remove the remaining pit material. Mining will begin in the southwest <br />corner, proceeding in approximately 200-foot strips oriented north to south. Mining will <br />