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Windsor East Mine, Exhibit D – Mining Plan September 2022 <br /> Page 2 | 4 <br /> <br />Agricultural, industrial, residential, and mining uses surround the property. <br />2.0 METHODS OF MINING <br />The typical mining procedure for all phases will be as follows. Any areas slated for protection will be identified in <br />the field to assure that mining operations will be set back as appropriate. The topsoil and overburden will be <br />stripped with scrapers and stockpiled in the designated stockpile areas identified in Exhibit C. Overburden found <br />on the site will also be used to fill in the reclamation slopes. Overburden and topsoil reserved for reclamation will <br />be vegetated and stabilized in accordance with Rule 3.1.9(1). Prior to mining, a dewatering trench will be <br />constructed around the perimeter of each phase. A sump hole will be created at the lowest point of each <br />dewatering trench. The sump holes and dewatering trenches will allow sediment to settle before the water is <br />pumped to the Cache la Poudre River using a dewatering pump in accordance with Colorado/NPDES discharge <br />permit regulations. Pipes will be used to transport the water from the mine to the Cache la Poudre River. The <br />location of the discharge pipes will be adjusted throughout the mining process. <br />When the mined alluvium is sufficiently dry, front-end loaders will excavate the material. The high wall of the mine <br />cells will not exceed a 1:1 slope. All mined material will be deposited on conveyors which will transport the <br />material to Martin Marietta’s existing plant site at the Parsons Mine (M-2009-082), directly east of Windsor East. <br />No materials processing will occur at the Windsor East Mine site. <br />Surface water within the mine areas will drain internally. Direct precipitation falling on a mine cell is collected in <br />the perimeter dewatering trench and pumped out. There will not be any uncontrolled releases of surface water <br />and sediment from mining areas. Storm water collected in the open mine will be managed in accordance with <br />Colorado/NPDES discharge permit requirements. <br />Water rights associated with the site will be used for dust control operations along the roads, stockpiles, transport <br />of material and berms. The water balance discussed in Exhibit G estimates the gallons per week necessary to <br />limit dust emissions. The water will be supplied using a 2,500-gallon water truck. <br />No explosives will be used to mine the site. <br />3.0 OVERBURDEN <br />Topsoil and overburden will be stripped with scrapers or a dozer and placed separately in temporary stockpiles <br />within the permit area limits. The topsoil will be segregated and stored separately from the overburden material <br />as required by Rule 3.1.9(1). The stockpiles will have an average height of 8 feet tall; they will have maximum 3:1 <br />(horizontal:vertical) side slopes. The topsoil stockpiles will be protected from wind and water erosion by <br />vegetative cover (see the Seed Mix for Upland Areas found in Exhibit E). The stockpiles will be broadcast seeded <br />and incorporated into the weed control program. Weed control consists of chemical treatments as needed in the <br />applicable fall and spring seasons. Topsoil and overburden stockpiles reserved for reclamation will be vegetated <br />and stabilized in accordance with Rule 3.1.9(1). <br />The overburden stockpiles will be continuously rotating. Initially, a portion of a phase will be stripped, and the <br />overburden stockpiled temporarily within the permit boundaries. Once the deposit has been mined from the <br />stripped portion, the temporary stockpile will be removed and used for reclamation. The remaining portion of the <br />cell will then be stripped, and the overburden will be stockpiled on the mine floor or placed immediately in the <br />reclamation slope. No excess overburden is anticipated for this site. <br />4.0 COMMODITIES TO BE MINED <br />The primary commodity to be mined will be aggregate and a secondary commodity will be gold. Martin Marietta <br />will supply local, county, and state governments, as well as private industry with aggregate from this facility. If <br />gold is mined it will be used for commercial purposes.