Laserfiche WebLink
6.4.4(b) <br />Revised 1/27/2011 <br />DRMS Quest #6 <br />topsoil from the site. As part of the reclamation process, the pit floor may be plated with 4"- 6" <br />. of reject gravel material from the mining and processing operations. <br />Reclamation will follow mining as closely as operationally feasible. Since the post mining land <br />use will be developed water resource, a significant part of site reclamation will be completed <br />prior to material extraction. The slurry wall will be constructed prior to the onset of mining <br />(Attachment II). THE MINING SLOPES, AS THEY APPROACH THE LOCATION OF A SLURRY WALL, <br />WILL ONLY BE MINED AT AN APPROPRIATE ANGLE (3H:1 V OR LESS) SUCH THAT THE INTEGRITY OF <br />THE VIRGIN EARTH PROTECTING THE SLURRY WALL IS MAINTAINED. AT OTHER TIMES DURING THE <br />MINING PROCESS, PIT SLOPES MAYBE STEEPER THAN 3H:I V. Pit slope mining configurations will <br />ensure that the pit slopes inboard of a slurry wall are stable under a wet or saturated condition. A <br />seepage barrier (slurry wall) will be necessary to separate ground water from raw water storage. <br />(Please see attached Drawings three and four and Attachment II.) (THE INTENT OF THE MINING IS <br />TO CREATE A RESER VOIR FOR THE CITY. ) <br />Reservoir excavation will range from about 6 feet to approximately 55 deep below the existing ground <br />surface. There will be no embankment fill around the perimeter of the reservoir. The overburden <br />excavated will include clays, clayey sands, clean to very clean silty sand, gravelly sands and sandy <br />gravels. <br />Earthmoving will be done with appropriate types and sizes of equipment, i.e. dozers, front-end <br />• loaders, scrapers, excavators, etc. Trucks designed (dump trucks, rock haul tricks) to move <br />materials on site will transport material around the mine site and processing area. <br />Slurry Wall Construction: Slurry or cut-off walls are a non-structural <br />constructed underground barrier to the movement of ground water from one area <br />to another area. Slurry walls are typically constructed through the excavation of a <br />trench of approximately one yard wide or wider. Bentonite slurry is used to <br />stabilize the trench during construction. A long-reach or rotary excavator is <br />generally used to dig the trench into a non-pervious bedrock layer that underlay's <br />the permeable, excavated overburden. Once the trench is excavated and while <br />maintaining the bentonite slurry, the trench is back filled with an impervious <br />mixture of blended overburden and bentonite; overburden, cement and bentonite; <br />or cement and bentonite. The backfilled trench is then covered with a cap to <br />protect the backfilled trench from deterioration. Over this and the surrounding <br />area, down to the toe of the reservoir basin will be placed a course gravel layer to <br />protect the surface area from erosion and inhibit the growth of vegetation. <br />The Applicant/Operator will provide detailed designs in the form of a Technical <br />Revision at a future date once other key permits and approvals are obtained from <br />other agencies. No slurry wall construction will begin until the Technical <br />• Revision is approved. A Conceptual Slurry Wall Construction Plan is provided as <br />part of this Application in Exhibit E (Please also see Attachment II). In addition,