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The erosion potential for the site will vary at different stages of construction. The initial <br />earthwork operations will remove topsoil and vegetation. This will expose bare earth to rainfall <br />erosion and wind erosion. As grading operations progress for cuts and fills, compaction and <br />wetting will reduce wind and rain erosion. Once grading is complete, all prescribed measures <br />will be implemented to limit sediment discharge off-site. installation of temporary seeding will <br />further reduce erosion potential. <br />Erosion and Sediment Control Measures <br />A portion of the property will be graded to provide earthwork for an adjacent transportation <br />project. A site access drive cut and a temporary gravel haul road will be constructed. Temporary <br />seeding and mulching will minimize wind and water erosion. The methods used to control <br />erosion and sediment during development of the subject property will comply with Garfield <br />County Engineer Specifications and Urban Drainage and Flood Control District, Urban Storm <br />Drainage Criteria Manual, Volumes 1, 2, & 3, June 2001. The predominant pollution expected <br />at the site during construction and under permanent conditions is sediment in storm water <br />runoff. The following are effective BMPs (Best Management Practices) which will be utilized on <br />site to help with erosion control. <br />Silt Fence <br />Silt fence is a sediment- trapping device that utilizes a special filter fabric to prevent <br />sediments from being carried offsite by water, as described in the Erosion Control <br />Reference Manual. Details for installing sift fences are included on the Erosion Control <br />Detail Sheet in Appendix C. Prior to beginning any earthwork activities, silt fences will be <br />installed as shown on the plan. The sift fence will protect the surrounding streets and <br />drainage ways from excessive sediment buildup. The silt fence along the property <br />boundaries shall remain in place and be regularly maintained until the temporary native <br />seeding is established and construction activities have been completed. <br />Vehicle Tracking Control <br />The construction access road with an entrance onto a paved road shall be graveled for a <br />minimum distance of 50 linear feet to retain mud and other potential pollutants on -site. <br />An approximate thickness of 9 inches of 3 — 6 inch angular rock is required. Vehicle <br />tracking control helps to insure that sediment from the site will not be transported to <br />adjoining roadways. This BMP must be inspected daily. Should the BMP measure not be <br />performing as intended and mud or soils are tracked onto paved public roads, the roads <br />shall be cleaned as soon as possible. No construction debris, materials, or soil deposits <br />shall be allowed to impede the smooth flow of traffic on public roads. Further BMPs may <br />be required including Vehicle Tracking Control with Wheel Wash if Vehicle Tracking <br />Control alone is not sufficient to protect adjoining paved roads. <br />Seeding and Mulching <br />Disturbed areas shall be seeded and mulched within 30 days following completion of <br />grading. Stockpiled soils that shall remain undisturbed for 30 or more days shall be <br />temporarily seeded and mulched with a non - irrigated native grass seed mix. Surface <br />roughening in large, sloping areas is preferable to smooth grading for preventing sediment <br />from being eroded and carried off -site by wind or water erosion. <br />Maintenance and Removal of Erosion Controls <br />Structural and vegetative erosion control BMP's will be inspected after every significant <br />precipitation event or snowmett or at least once every week to confirm that they are <br />properly installed and operational. Replace or repair gravel fitters and silt fences as <br />needed. <br />[LC ..S 1OL1.6.6S <br />Page 2 <br />