Module 4: Temporary Sediment Controls

Learning Objectives n Identify locations for sediment control BMPs n Identify applications for different types of sediment control BMPs n Identify installation requirements for sediment control BMPs

Groups of BMP Techniques n Soil Stabilization n Sediment Control n Other BMPs Tracking Controls Wind Erosion Controls Non-Storm Water Management Materials and Waste Management

Sediment Control BMPs Introduction n Filtration: Silt Fence BMP n Basins and Traps: Desilting Basin, Sediment Trap, and Check Dam BMPs n Removal: Street Sweeping and Vacuuming BMP n Interception: Fiber Rolls, Gravel Bag Berm, Sand Bag, and Strawbale BMPs n Inlet Protection BMP

Silt Fence BMP (SC1) Field Manual –Page 62

Silt Fence BMP (SC1) Use n Toe of bare slopes n Down slope of exposed soil stockpiles along critical areas such as streams

Silt Fence BMP (SC1) Limitations n Not in mid-slope locations or slopes steeper than 4:1 n Maintenance required n Not for large water volumes n Not for live streams

Silt Fence BMP (SC1) Additional Considerations n Keying in fence (vertical entrenchment or ‘L’ entrenchment) n Stabilized or unstabilized installation n Proper positioning Toe of slope On the contour

Silt Fence BMP (SC1)

Silt Fence BMP Detail (SC1) Silt Fence Cross Section Silt Fence Oblique View Anchor Trench Support Fencing Field Manual –Page 65

Desilting Basin (SC2) Field Manual –Page 66

Use n Sediment may enter drainage or watercourse (cannot be used within a waterway) n Drainage area is between 2 and 4 ha (5-10 acres) n Failure will not cause loss of life or property Desilting Basin (SC2)

Limitations n Requires large surface area for settlement n Cannot be located in live stream n May be a safety concern requiring fencing n Risk of failure under high flow conditions

Desilting Basin (SC2) Additional Considerations n Locate where permanent detention basins will be n Size  capacity equal to 100 m 3 of storage per hectare  length more than twice the width  1 to 1.5 m depth

Desilting Basin (SC2) Additional Considerations (cont) n Overflows or bypasses protected from scour n Drainage within 72 hours following storm events Access for maintenance Inlet protection: rock or vegetation Forebay to collect debris “High hazard” Basins must be approved by P.E.

Desilting Basin BMP Detail (SC2) Stabilized Outlet Emergency Spillway Stabilized Inlet Field Manual –Pages 70 and 71

Sediment Trap (SC3) Field Manual –Page 72

Use n Located across a drainage way n Excavated/constructed of earthen material n For drainage areas < 2ha Sediment Trap (SC3)

Limitations n Requires large surface area to permit settling n Not appropriate for drainage areas > 2ha n Hazardous; may require fencing n Not appropriate in live stream n May be a safety concern requiring fencing

Sediment Trap (SC3) Additional Considerations n Use where failure will not cause loss of life or property n Capacity and Dimensions  Settling zone: 130 m 3 /ha of drainage area  storage zone: 65 m 3 /ha of drainage area  Length to width >3:1

Sediment Trap (SC3) Additional Considerations (cont) n Basins >1,000m 3 and/or levees >1.5m must be approved by registered PE n Must have access for maintenance

Sediment Trap BMP Detail (SC3) Sediment trap Stabilized Oultet Field Manual –Page 75

Check Dams (SC4) Field Manual –Page 76

Check Dams (SC4) Use n Located across a drainage way n Constructed of rocks, sandbags, or fiber rolls n Small channels and drainage areas < 4ha n Can be used in steep channels with high runoff velocities n In association with grass-lined channels

Check Dams (SC4) Limitations n Not appropriate for channel areas > 4ha n Not in live stream areas or well-vegetated channels n Will require maintenance after high flows n Sediment can be re-suspended n Not to be constructed using silt fence

Additional Considerations n Dam height and spacing n Safely pass high stormwater flows n Remove when grass established n Hand work may be required to shape dam Check Dams (SC4)

Check Dams BMP Detail (SC4) Check Dam Cross Section Lowered Center Spillway Field Manual –Page 78

Dugout Ditch Basin BMP (SC11) Sediment Control Basin Field Manual –Page 100

Dugout Ditch Basin BMP (SC11) Use n One or a series of small dugout basins located within a flow channel n Reduce runoff velocity, promote sediment retention n Sediment traps, interceptor ditches, toe of slope protection n Spacing dependent on ditch slope

Dugout Ditch Basin BMP (SC11) Limitations n Not to be used in live streams n Not to be used in vegetated channels n Require maintenance n Trapped sediment can be resuspended during subsequent storms

Dugout Ditch Basin BMP (SC11) Additional Considerations n Designed for 2-year, 24 hour rain event n Can remain in place and seeded with permanent seeding of ditch

Dugout Ditch Basin BMP Detail (SC11) Cross Section Dugout basins Field Manual –Page 102

Fiber Rolls (SC5) and Gravel Bag Berm (SC6) SC5 - Field Manual – Page 79 SC6 - Field Manual – Page 82

Fiber Rolls (SC5) and Gravel Bag Berm (SC6) Use n Designed to shorten slope lengths and intercept and slow sheet flow, reduce flow velocity, and trap and remove some sediment n Fiber Rolls - straw, flax, rolled and bound n Gravel Bag Berms - a single roll of gravel bags n Used on the face of slopes, at the top of slopes, and at grade breaks

Fiber Rolls (SC5) and Gravel Bag Berm (SC6) Limitations n Gravel Bags may rupture when removed, are laborious to install, and have limited durability for long projects n Fiber rolls may not degrade in the short term

Additional Considerations n Locate on level contour n Fiber rolls are typically left in place n Gravel bag berms may be removed Fiber Rolls (SC5) and Gravel Bag Berm (SC6)

Fiber Rolls

Fiber Rolls BMP Detail (SC5) Roll Anchored in Trench Rolls placed on contour Field Manual –Page 81

Gravel Berm Bag BMP Detail (SC6) Gravel Bags placed on contour Field Manual –Page 84

Street Sweeping and Vacuuming (SC7) Field Manual –Page 85

Street Sweeping and Vacuuming (SC7) Use n Remove tracked soil to prevent it’s entry into storm drain or watercourse

Limitations n Not effective in wet conditions n May require daily treatment Street Sweeping and Vacuuming (SC7)

Additional Considerations n May collect hazardous materials

Sandbag Barrier (SC8) Field Manual –Page 87

Sandbag Barrier (SC8) Use n Linear barrier of stacked sandbags n Slows sheet water flow n Increases detention time and sedimentation

Sandbag Barrier (SC8) Limitations n Installation can be labor intensive n Only where the up-gradient area is small (i.e., < 2 ha) n Limited durability

Sandbag Barrier (SC8) Additional Considerations n To create a temporary sediment basin n As sediment berms in stream beds (< 2ha) n When extended construction period limits the use of either silt fences or straw bale barriers n Along the perimeter of vehicle and equipment fueling and maintenance areas or chemical storage areas n To capture and detain non-storm water flows until proper cleaning operations occur

Sand Bag Barriers BMP Detail (SC8) Plan View Lowered Center Spillway Field Manual –Page 90

Straw Bale Barriers (SC9) Field Manual –Page 91

Straw Bale Barriers (SC9) Use n Linear barrier of straw bales designed to intercept and slow sheet flow n Increases on-site detention time and sedimentation n Along the perimeter of site and stream channels n Along roadways and around stockpiles n Across minor swales

Straw Bale Barriers (SC9) Limitations n Not in channels or live streams with high flows n Labor intensive installation and removal n Maintenance intensive (disintegration) n Can not be used on paved surfaces n Drainage area small (<100m) slopes short (30m)

Straw Bale Barriers (SC9) Additional Considerations n Wooden stakes used to anchor bales to soil n Bales embedded into soil n Install bales on the contour n Tightly abut bales n Offset second rows of bales when used

Straw Bale Barriers (SC9)

Straw Bale Barriers BMP Detail (SC9) Bales embedded in soil Bales overlapping Bales anchored with stakes Field Manual –Page 93

Storm Drain Inlet Protection (SC10) Field Manual –Page 94

Storm Drain Inlet Protection (SC10) Use n Devices used to prevent sediment from entering storm drains n Used with other BMPs as the last defense n Appropriate Use:  Where ponding of water will not cause flooding  During wet and snow-melt seasons  Need to allow water into inlet

Storm Drain Inlet Protection (SC10) Limitations n Last line of defense n High flow may damage n Heavily sediment laden storm water may plug n Adversely effected by ponding

Additional Considerations n Various BMPs applicable to sediment control n Filter fabric n Sandbags n Straw bales n Gravel check dam Storm Drain Inlet Protection (SC10)

No inlet protection Filter Fabric Application

Storm Drain Inlet Protection BMP Detail (SC10) Straw Bale Application Filter Fabric Application Field Manual –Page 98

Storm Drain Inlet Protection BMP Detail (SC10) Sand Bag Application Gravel Check Dam Application Field Manual –Page 99

Summary of SC BMPs n Toolbox of different techniques n Need to be adapted to site conditions n Capture sediment from runoff n Require maintenance n Generally removed after vegetation established

Discussion photo

The end of Sediment Control BMPs Discussion