2. What is Erosion and Sedimentation ? Bill Laflamme CPESC, Office of the Commissioner MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION Protecting Maine’s Air, Land and Water

3. EROSION AND SEDIMENTATION MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep Erosion = Movement of soil by action of water or wind. Erosion is natural Accelerated Erosion is not Sedimentation = “settling out” of soil particle from the water

4. MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep WHY DO SOILS ERODE?

5. MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep SOILS ERODE based on a combination of factors including: The size, shape and cohesion factor of the soil The intensity, duration and frequency of rainfall (or wind events) The size of the watershed, slope and cover of the area where the soil is located

6. MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep EROSION FACTOR Size Shape Cohesion

7. MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep Relative Size of Soil Particles

8. SURFACE AREA OF ONE GRAM OF MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep Sand 16 in 2 Silt 10 ft 2 Clay ¼ acre

9. MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep MORE SURFACE AREA EQUALS MORE PHOSPHOROUS

10. SHAPE MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep Sand – Rounded, blocky Silt – Same as sand, just smaller Clay – Plate-like

11. Why Become Certified ? MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep

13. Drains well, Compacts well but will not stay together if exposed No Cohesion (stickiness) SAND

14. Why Become Certified ? MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep

15. SILT MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep Water moves through slowly Compacts at the right moisture content Little cohesion - – Sloppy when wet, – Talcum powder when dry

16. Why Become Certified ? MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep

17. CLAY MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep Moisture content constant, Difficult to handle and compact if wet (Rock hard when dry) High Cohesion - Sticky Feel – (plates stick together like wet plates of glass)

18. Why Become Certified ? MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep

19. Soil Texture Percent Sand Percent Silt Percent Clay Sand85 – 1000 – 150 -10 Sandy Loam45 – 850 – 500 – 20 Loam23 – 5327 – 507 – 28 Silt Loam 0 – 5050 -850 – 28 Silty Clay 0 – 2040 -7228 - 40

20. Find Out More MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep

21. RAIN MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep Intensity – Raindrops, How big and fast Duration – How long Frequency – How much volume, how often – 10 year storm, 100 year storm

22. MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep

24. RUNOFF MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep Runoff begins when rain has no place else to go

25. MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep

26. RUNOFF MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep Watershed Slope of ground Cover (vegetation) Soils (infiltration)

27. SLOPE MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep The steeper the faster

28. MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep

29. COVER MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep Stop the Raindrop Store the Raindrop Canopy (leaves) Surface Roughness

30. MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep

31. SOILS MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep Infiltration Rate Soil Texture Surface Sealing Roughness

32. MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep

33. EROSION MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep Rain drop Sheet Rill Gully

34. RAIN DROP EROSION MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep

35. RAIN DROP EROSION The harder the rain and the finer the soil texture, the more raindrop erosion will occur. Consider that a large raindrop will fall at a rate of 30 ft/sec and may be up to 250 time larger than a silt particle. Sand on the other-hand may be the same or only half the size of that raindrop Soil Sealing - Pounding the Surface

36. SHEET EROSION MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep Sheet flow over bare soil picks up soil Plus soil that was splashed up by the raindrop is now in suspension and will move with the sheet of water. Sheet flow can be up to ½ inch deep 1/8th of and inch of soil loss per acre will fill a 10 wheel dump truck (15 cu.yds. or 25 tons). How fast and far this “sheet” of water flows depends on how deep the water is, the texture of the soil, and the steepness and smoothness of the land.

37. MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep

38. RILL EROSION MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep When sheet flow begins to concentrate depth, increases power and begins to cut. Rills are technically no more than 1.0 inches deep and will be spread out across a slope. Rills pull together and are short lived

40. GULLY EROSION MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep Rills coming together on a slope Flow volume increases – Increase Depth Velocity = Slope (Critical) Power increases to a point that the bottom cuts down

41. GULLY EROSION MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep They will continue to erode from the bottom up, or head cut. The side slopes are usually vertical and will then begin to collapse under their own weight. On Construction Sites they usually form in bottom of channels and move upstream A gully can be as small as 2 inches by 2 inches to as big as the Grand Canyon

45. EROSION CONTROL MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep

46. SEDIMENTATION MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep Sediment is soil suspended in water Sedimentation is the settling out of sediment Decrease Velocity = Sedimentation – Decrease Velocity – Ponding Usually occurs by grade change

47. SEDIMENTATION MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep Sands? – Always Silts ? – Sometimes Clays ? – Almost Never

48. SEDIMENTATION MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep Sheet Flow and Shallow Concentrated – Flatten grade – Roughen surface - filter strip – Barriers – Silt Fence Channel Flow – Must Stop velocity – Ponding – Can put back in sheet flow – filter strips, buffers

50. Courtesy – Peter G. Knight

51. SEDIMENT CONTROL MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION www.maine.gov/dep Last Line of Defense Decrease Power = Sedimentation – Decrease Velocity – Ponding Silt Fence, Sediment ponds – Decrease Velocity (and Depth) – Filtering Go from Concentrated Flow to Sheet Flow Level Lip Spreaders, Filter Strips, Buffers

52. www.maine.gov/dep