Laserfiche WebLink
Climax Molybdenum Company HENDERSON MINE SWMP <br /> Empire, CO April 2021 <br /> • Install mulch, excelsior blankets or reseed areas on disturbed slopes greater than 3:1 and <br /> consideration should be given to installation on slopes between 5:1 and 3:1 on a case- <br /> by-case basis depending on the length, exposure, and texture of the soils on the slope. <br /> • Avoid slopes steeper than 2:1 and when unavoidable, rock protection (rip rap) or <br /> excelsior mats with netting shall be installed. <br /> • Install rip rap and at least 6-inches of suitable bedding in all water now channels where <br /> the design flow will exceed—2 feet per second. Generally, suitable bedding ranges from <br /> a minimum diameter of sand to a maximum diameter of 2-3 inches of coarse granular <br /> soils. <br /> • Furrow contour side hill slopes whenever suitable equipment is available. Otherwise, <br /> final grading shall be performed in a manner that will result in tracks and depressions <br /> contoured across the slope instead of a down "fall-line." This will not only minimize <br /> wind erosion but will also "roughen" the earth to provide a microclimate of wind <br /> protection for new plants and will help conserve precipitation for use in growth of new <br /> seed. <br /> • Minimize the time that bare soil is exposed. <br /> • Install check dams and water bars wherever the slope exceeds approximately two <br /> percent(-2%)to reduce water velocities and erosion potential in constructed swales and <br /> channels. Rip rap linings shall be installed in steeper slopes or where the velocity <br /> exceeds two (2)feet per second. <br /> • Minimize the disturbance of existing vegetation. <br /> • Reseed and apply mulch as soon as possible to disturbed areas where erosion is probable. <br /> Mulch may be natural, consisting of slash, brush, manure, and vegetation previously <br /> chipped and stockpiled; and/or clean straw, free from noxious weed seed, mold, and <br /> other harmful elements; or wood cellulose fiber. <br /> • Apply erosion control mats to all cut slopes steeper than 3:1. Staples shall be installed <br /> at a maximum spacing of 4 feet. Mats shall overlap on the ends and sides at least 6 <br /> inches. Regular duty excelsior mats shall be used for slopes less than 2:1. Heavy duty <br /> excelsior or jute mats shall be used for slopes greater than 2:1. <br /> • Where erosion scarps have developed (particularly along the faces of flood detention <br /> structures), loose granular material shall be removed, and the scarp filled with suitable <br /> soils to the original profile of the bank or slightly above the original profile. If the scarp <br /> is not completely filled, the steeper area at the brow of the scarp will encourage erosion <br /> and may cause redevelopment of the scarp. The area upstream from the scarp shall be <br /> carefully inspected to determine if there was an irregularity in the ground profile that <br /> caused storm water to concentrate and erode the soils. Any such irregularity shall be <br /> removed by the most appropriate BMP listed herein. <br /> • Cover soils known to have a relatively high erosion potential with coarser textured <br /> erosion resistant soils and mulch/reseed the topsoil. <br /> • Where feasible, bypass live stream flows around construction sites during earthwork <br /> activities by installation of temporary (or permanent)pipes or rock lined ditches. <br /> Page 5-2 <br />