12/19/2001 Env Bd Packet - Laserfiche WebLink

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Sequencing outlets before opening major areas for development. Install additional needed runoff - control measures as grading takes place. The main runoff - conveyance system with inlet and outlet protection devices should be installed early, and used to convey stormwater runoff through the development site without creating gullies and washes. • Begin grubbing and grading as soon as key erosion- and sediment - control measures are in place. Once a scheduled development area is cleared, grading should follow immediately so that protective ground cover can be reestablished quickly. • Install inlet protection for storm drains as soon as the drain is functional to trap sediment on site in shallow pools and to allow flood flows to safely enter the storm - drainage system. • Install outlet protection at the same time as the conveyance system to prevent damage to the receiving stream. • Site clearing and project construction increases storm runoff, often making stream- bank - stabilization work more difficult and costly. • Do not leave any area bare and exposed for extended periods (see NPDES permit requirements). Leave adjoining areas planned for development or ones that are to be used for borrow and disposal undisturbed as long as possible to serve as natural buffer zones. • Runoff control is essential during the grading operation. Temporary diversions, slope drains, and inlet and outlet protection installed in a timely manner can be very effective in controlling erosion during this critical period of development. • After the land is cleared and graded, apply surface stabilization on graded areas, channels, dikes and other disturbed areas. Stabilize any disturbed area where active construction will not take place for 21 working days (see NPDES permit requirements) by temporary seeding and/or mulching or by other suitable means. • Install permanent stabilization measures after final grading, in accordance with the vegetative plan. Temporary seeding and/or mulching may be necessary during extreme weather conditions with permanent vegetation measures delayed until a more suitable installation time. • Coordinate building construction with other development activities so that all work can take place in an orderly manner and on schedule. Experience shows that careful project scheduling improves efficiency, reduces cost and lowers the potential for erosion and sedimentation problems. • Landscaping and final stabilization is the last major construction phase, but the topsoil stockpiling, tree preser- vation, undisturbed buffer area, and well - planned road locations established earlier in the project may deter- mine the ease or difficulty of this activity. All disturbed areas should have permanent stabilization practices applied. Unstable sediment should be removed from sediment basins and traps and incorporated into the topsoil, not just spread on the surface. • All temporary structures should be removed after the area above has been properly stabilized. Borrow and disposal areas should be permanently vegetated or otherwise stabilized. In planning construction work, it may be helpful to outline all land - disturbing activities necessary to complete the proposed project. • Develop a list of all practices needed to control erosion and sedimentation on the site. These two lists can then be combined in logical order to provide a practical and effective construction - sequence schedule. Metropolitan Council/Barr Engineering Co. 3-65