Part IV(a): BMPs for Erosion, Sediment, Velocity Control

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1 Part IV(a): BMPs for Erosion, Sediment, Velocity Control

2 Find Design Standards and Specifications for Iowa Erosion and Sediment Control Practices at:

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5 Erosion Control Keeping the soil in place through vegetation or other means.

6 Tools in the Toolbox EROSION CONTROL PRACTICES Maintain existing vegetation Compost blankets Mulching Temporary seeding, Permanent seeding, Sodding Rolled Erosion Control Products (RECPs) Surface roughening-grading strategies Turf Reinforcement Mats Vegetative filter strips

7 Sediment Control Dealing with soil once it is dislodged and in suspension. Trapping sediment that is moving in the erosion process and retaining it onsite. Typically, sediment control is achieved by temporarily impounding sediment laden runoff. Slowing flows and filtering with vegetative buffering can also contain sediment on site.

8 Tools in the Toolbox SEDIMENT CONTROL PRACTICES Compost Filter Berms Filter Socks Wattles Flocculants Floatation Silt Curtain Inlet Protection Sediment Basins and Traps Silt Fence and Similar Practices Stabilized Exits

9 Velocity Control Slowing concentrated flows to reduce erosive impacts from high flows Some trapping of sediment may occur

10 Tools in the Toolbox VELOCITY CONTROL PRACTICES Check Dam Diversion Structure Level Spreader Rock Chutes and Flumes Rock Outlet Protection Flow Transition Mat Temporary Slope Drain

11 Erosion Controls Except as precluded by snow cover, stabilization measures shall be initiated on all disturbed areas as soon as practical but in no case where construction activity will not occur for a period of 21 or more calendar days later than the 14th day after no construction activity has occurred on such area.

12 Maintaining On-Site Vegetation Maintaining as much existing vegetation as possible during construction, including grass, shrubs, trees, and other ground cover can reduce the need for new vegetation. Phasing construction disturbs smaller areas for shorter periods, preserves vegetation, and reduces site exposure to soil erosion. Phasing also reduces the need for and difficulties in stabilizing a large area of new vegetation at one time.

13 Created building envelope Protected a lot of the existing vegetation

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15 Mulching Mulching is the application of organic material over soil that is bare or immediately over soil that has been seeded. Mulch prevents erosion by preventing the detachment of soil particles, slows runoff velocity, and retains moisture to improve germination and establishment of vegetative cover. Applied on exposed soils as a temporary control where soil grading or landscaping has taken place or in conjunction with temporary or permanent seeding. When time constraints prevent the establishment of vegetation (seeding), mulch such as wood chips, straw, or compost can be used independently as a temporary soil stabilization practice that protects the soil surface until vegetation establishment can be completed.

16 Mulch or Compost Mulch Straw/hay, use tackifier or crimp Wood, shredded, chips, recycled wood products Compost, from leaf/grass yard waste DON T use loose mulch in drainage ways or areas with concentrated flows

17 Blown Straw

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19 Hydromulch Paper 30% Paper / 70% wood or 50/50 Wood Tackifier Guar Gum Slick paper clay Bonded Fiber Matrix Best to drill or broadcast seed into or on soil then spray hydromulch on top

20 Requirements for Application Water source Additives (seed mix fertilizer, tack) Spray in two directions for more even application Spray with nozzle close to the ground

21 Bonded Fiber Matrix Thicker, synthetic fibers, tackifier Steeper slopes Can t be used in channels Uniform application

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23 Compost Blanket A compost blanket is a 1 to 4 inch surface application of compost/mulch or a blend of both to protect areas with erosive potential. Used to protect bare soil surfaces from raindrop impact, prevent/reduce sediment loss, reduce surface water runoff, and promote seed growth for establishment of ground cover.

24 Compost Blankets Mixed with/without seed and do not incorporate Provides excellent water holding capacity Applied with blower Not useful on very steep slopes and not in areas with concentrated flow

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26 Temporary Seeding Temporary seeding is a means of growing a short-term (less than one-year) vegetative cover on disturbed areas that may be in danger of erosion. 14/21 day rule

27 Vegetation Temporary Nurse crop Wheat Annual rye Oats Legumes Clovers

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29 Permanent Seeding Means of establishing permanent, perennial vegetative cover on disturbed areas. Prevents erosion, remove sediment from runoff, and reduce the volume of runoff. Stabilizes ground after grading and landdisturbing activities have been completed, or whenever construction activities will be halted for a time period longer than temporary seeding can provide protection (i.e. one growing season). Final vegetative cover

30 Vegetation Cool Season Fescue Ryegrass Bluegrass Warm Season Buffalograssnative Blue Grammanative

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32 Source: New York Department of Environmental Conservation Sod could be used in critical areas such as storm drain inlets, steep slopes, and any area where conditions make seeding impractical or impossible.

33 Permanent Vegetative Cover Final vegetative cover consists of 70% establishment uniformly across the entire site

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35 Filter Strips Vegetated strips of land used on relatively levels areas to maintain sheet flow Removes pollutants through filtering Sod-forming grasses are used Minimize steep slopes

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37 RECPs Temporary rolled erosion control products (RECPs) consist of prefabricated blankets or netting which are formed from both natural and synthetic materials. Used as a temporary surface stabilizing measure and to aid in the establishment of vegetation. Used on steep slopes and in vegetated channels along with ditch checks.

38 Rolled Erosion Control Products Blankets Straw Excelsior Coir/Coconut Netting Plastic Jute Anti-washed jute

39 Netting Open weave Over mulch During good growing conditions when vegetation should establish quickly Not recommended for use in channels

40 Blankets Short Term Degradable 3-12 foot widths Straw or Wood (Excelsior) 9 months to 18 months Long Term Degradable Straw/Coconut, Wood, Coconut 1 to 2 years

41 Blanket Installation Area fine graded/no clods Good soil contact Appropriate staple pattern Toed in at edges Proper overlap between blankets Do not use in improper site conditions Use for areas where vegetation should be fully established prior to blanket degradation

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43 Turf Reinforcement Mats (TRMs) Composed of non-degradable synthetic fibers, filaments, nets, wire meshes, etc. Provide immediate erosion protection, enhance vegetation establishment, and permanently reinforce vegetation during and after maturation. Used on steep slopes and in hydraulic applications such as high flow ditches and channels, stream banks, shorelines, and inlet/outlet structures.

44 TRMs Composite TRM s Partially degradable Protection of blanket plus reinforcement Synthetic TRM s Permanent

45 TRM Installation Area fine graded/no clods Good soil contact Appropriate staple pattern for the use Toed in at edges Proper overlap between blankets

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49 Dust Control Water used most often Used when soil conditions are dry Use in soil disturbed and traffic areas Environmental and safety issues

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51 Surface Roughening Temporary practice that reduces soil loss by reducing the flow velocity of runoff. Surface roughening may also be used as a method of reducing dust. For slopes where additional grading is anticipated prior to permanent/temporary stabilization. To reduce runoff velocity, trap sediment, increase infiltration, and aid in the establishment of vegetative cover. Typically performed as an end-of-day practice.

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53 Sediment Controls

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55 Filter Berm A windrow-shaped (triangular) structure that can include mulch, composted materials or other organic products. Used to slow flows, capture and degrade chemical pollutants, and trap sediment. Applications include perimeter control, slope length reduction, flow diversion for small drainage areas, environmentally sensitive areas such as wetlands and waterways, at the edge of gravel parking lots, and general areas under construction. Used in flat areas

56 Filter Berms Don t use in waterways Not velocity control Texas Coastal Watershed Program

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58 Filter Sock A filter sock is a tubular mesh sock filled with a filter material that normally filled with wood mulch, compost or similar organic products. Filter socks slow flow velocity, capture and degrade chemical pollutants, and trap sediment. They are most effective when designed to provide comprehensive water and sediment control throughout a construction site and if used in conjunction with erosion control practices. Used for perimeter control, inlet protection, slope length reduction, flow diversion for small drainage areas, environmentally sensitive areas such as wetlands and waterways, at the edge of gravel parking lots, and general areas under construction.

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60 Swale out, trenc Stake J-hooks

61 Filter Socks

62 Maintenance Repair or replace split, torn, unraveling, or slumping filter socks. To maintain sheet flows, sediment that accumulates in the sock must be periodically removed when accumulation reaches one-half the designated sediment storage depth Replace when driven over

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64 Wattles Wattles are a sediment and stormwater velocity control device. Tubes of straw, rice straw, or coconut husk encased in ultraviolet degradable plastic netting or 100% biodegradable burlap material. Wattles help stabilize slopes by breaking up the length, and by slowing and spreading overland water flow. Similar in installation to filter socks Issues with floating and driving over

65 Maintenance Repair or replace split, torn, unraveling, or slumping wattles. To maintain sheet flows, sediment that accumulates in the wattle must be periodically removed when accumulation reaches one-half the designated sediment storage depth Replace when driven over

66 Bio-Degradable Wattles/Logs Straw Excelsior Coconut

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70 Silt Fence Temporary sediment barrier of geotextile fabric that is anchored into the ground and supported by posts on the downstream side of the fabric. Temporarily impound runoff and retain sediment onsite. Most effective when designed to provide comprehensive water and sediment control throughout a construction site and if used in conjunction with erosion control practices. May also be used to create a sediment trap for removal of suspended particles from low volume concentrated flows.

71 Installation Slice, bury edge, trenched 6-8 in Use posts of 4 foot minimum steel (T-section) Low flow areas space posts 4-5 ft, highconcentrated flows 1-3 ft Fasten with wire or plastic

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73 Silt Fence Placement Correct Incorrect

74 Designs called J-hooks insure water & sediment pond behind each silt fence.

75 Proper Installation

76 Remove sediment when half full or Add new section of silt fence Repair or replace torn fence, reattach when necessary