Erosion and Sediment Control Systems M. D. Smolen Biosystems and Agricultural Engineering

1. Erosion and Sediment Control Systems M. D. SmolenBiosystems and Agricultural Engineering †HTL

2. General Principals of Erosion and Sediment Control • First control erosion on site. • Capture the sediment on site. • Control outlet energy to prevent off-site damage.

3. Specific Erosion Control Principals • Limit extent and duration of grading • Protect the land surface • Divert runoff from upslope areas • Keep runoff velocities low • Construct stable channels

4. Establish the perimeter and buffer areas Phase grading to match the construction schedule

5. Protect the Surface • Use temporary or permanent vegetation • Apply mulch (fastened down)

6. Mulch can be as good as grass!

7. Tracking is not used enough, and when used it is often done wrong. It should be up and down the slope.

8. Sometimes a nurse crop of small grain can help the permanent grass get started.

9. Divert Runoff from Upslope Areas • Use a diversion dike and channel. • Divert clean water Treating clean water is expensive! Work Area

10. Divert Off-site Water

11. Keep Velocities Low Limit slope length - use terraces and diversions

12. Terraces limit length of slope

13. Never let flow cascade over a fill slope Use a chute, a pipe, or a channel to carry water down the slope

14. A chute can protect the slope, but high velocity water can erode down slope.

15. High velocity at the end of the chute can cause substantial erosion.

16. A temporary pipe drop can be extremely effective.

17. Construct Stable Channels • Steep channels should be lined. • Channels must be big enough to carry the flow. • Channels must be free of obstructions and protected from sediment.

18. Stable channels

19. Channel Liners • Temporary (fabric, straw with netting, excelsior) • Permanent (grass, riprap, gabions, concrete)

20. Capture Sediment Near the Source - the second line of defense • Barriers (Silt Fence, Hay Bales) • Inlet protection devices (Fabric) • Sediment Traps • Detention Basins

21. You cannot filter sediment-laden runoff! Filters clog too quickly with sedimentand fail. All sediment control device works by slowing the velocity causing the sediment to settle out.

22. Sediment Traps and Barriers • The trap is a small basin with a gravel outlet (controls up to 5 acres) • Barriers: silt fence, hay bales Inexpensive and effective, if installed properly and maintained

24. Silt fence are effective, but they... • Must be installed properly • Must be maintained • Require planning for good access • Require planning for sedimentation potential • Can’t handle concentrated flow • Need a good outlet

25. Silt fence must be installed properly.

26. Silt Fence • Bury at least 6 in. • Use sturdy, steel posts every 6 ft. • Install on the contour. • 100 ft of fence per 1/4 acre. Inspect and repair frequently

27. Silt fences can’t handle concentrated flows.

28. Silt Fence • Provide settling area above the fence • Anticipate locations for deposition • Clean out and repair

29. A rock berm. More substantial than silt fence.

30. Hay bales are not effective sediment barriers because: • They clog quickly • They decompose rapidly • They are difficult to install properly • They work – but only for a while They are best for temporary installations

31. Hay bale barriers don’t work.

32. Inlet Protection Devices • Area up to 1 acre • Should be supported at top • Must be buried 6 in at bottom • Requires maintenance after every storm

33. The gravel donut – Inlet Protection

34. Block and gravel – Inlet Protection

35. Excavation – Inlet Protection

36. Construction entrance, roads, and parking

37. Establish the roads and the drainage to protect the area.

38. A System for Erosion and Sediment Control • Install control measures first. • Phase the grading. • Establish traffic pattern. • Protect cut and fill slopes • Stabilize the surface • Maintain the system.