Post Construction Erosion Controls
Erosion Control Permanent Controls Native Vegetation Preservation Hydroseeding & Soil Stabilizers Soil Roughening Soil Stabilizers Geotextiles
Vegetation is the Best Erosion Control
Using Vegetation as a BMP
Retain Existing Vegetation Wherever possible, existing vegetation should be preserved.
Native Growth Preservation Revegetate a site with native plants Save the existing vegetation along with the top 6 to 12 inches of topsoil It contains nutrients, seeds and organic matter Material may be chipped and stockpiled until completion of grading Then re-spread on roughened slope
Reuse Natural Groundcover Protect stockpiles to reapply topsoil after grading is is completed
Hydraulic Seeding One of the most common seeding methods for construction sites
The seed and a trace amount of mulch are applied with a hydroseeder
Irrigation is Necessary In Arid Environments Irrigation is is needed to start growth, but also may be needed for site maintenance
Soil Stabilizers Types: Plant-Material Based (short-lived) Guar, psyllium, starch Plant-Material Based (long-lived) Pitch and rosin emulsion Polymeric Emulsion Blends Acrylic copolymers, acrylates, acrylamides Petroleum or Resin-Based Emulsions Cementitious-Based Binder Gypsum
Bonded Fiber Matrices Hydraulically-applied system composed of long strand mulch fibers joined together by highstrength adhesives. The combination of mulch and adhesive creates a continuous, three-dimensional blanket. When dry, creates a high strength, porous and erosion resistant mat.
Soil stabilizers have three applications. (1) Stand-alone application of liquid that forms a crust on the soil surface by binding soil particles together. (2) A tackifying agent applied over mulch as an alternative to crimping.
Or, (3) in combination with hydraulic mulches to create a hydraulic matrix.
Hydraulic Mulches Hydraulic Mulches consist of small wood fibers or recycled paper. They act as a carrier for seed They help modify the soil temperature and hold moisture so the seed can germinate
Soil Roughening
Track Walking
Serrated Slopes Serrated slopes are not cut as as deep as as stepped slopes, but provide the same benefits such as as shorter slope length, seed and moisture retention Photo by J. McCullah, All Rights Reserved
Slope Protection Rolled Erosion Control Products
Blanket Types (right to left) jute, straw, straw-coconut, coconut, synthetic, and curled wood fiber.
Post Construction Sediment Controls
Sediment Control during Post-Construction Phase How Sediment Control Measures Function: Most sediment control measures rely on settling Sediment-laden water must be allowed to pond in order for sediment to settle Settling time is dependent on particle size Other sediment control measures filter sediment
Check Dams
Sediment Traps and Drainage Basins Prevent bank erosion by protecting basin sides
Sediment Basin Guidelines There are specific guidelines for sediment basin design 3,600 cubic feet of storage per acre, or Pursuant to local ordinance
Sediment Basin Management Sites with fine-grained soils such as silts and clays may require further filtration(due to length of required holding time). Do not detain water more than 48 hours due to mosquito breeding potential. Local jurisdictions may require shorter (24 hour) draw down times.
Sediment Basin Maintenance Sediment removed from basins must be placed, compacted, and stabilized to avoid erosion and remobilization If there is a potential for the sediment to be contaminated, it must be tested and disposed of properly
Good Housekeeping
Good Housekeeping?
Materials Delivery and Designate delivery and storage areas Cover and contain stockpiles and other materials Use secondary containment Develop spill response protocols and establish spill stations Storage
Stockpiles Place perimeter controls around stockpiles Cover when necessary
Cover materials storage areas.
Designated Areas Good housekeeping keep the site clean Use designated areas for waste storage outside of gutters and away from drain inlets Contain, segregate and recycle wastes Educate Site Personnel!
Concrete Wash Out Areas
Vehicle and Equipment Management Areas Use designated flat, protected areas for parking, fueling and maintenance (locate away from sensitive areas and drain inlets) Inspect vehicles and equipment regularly for leaks and other problems Educate Site Personnel!
Stage, fuel and maintain equipment in protected areas away from drain inlets to prevent contamination of stormwater
Portable Toilet Placement Locate in a flat area at least 50 feet away from street/drain inlets If you see one tipped over, set it upright and report if necessary If any possibility of discharge to storm drain, do ph test, take sample for lab, and Report any leaks or spills immediately
Construction BMPs are also Good Housekeeping Procedures
Concrete and Paving Operations Avoid paving & concrete work during rain events Use designated concrete wash-out area Prevent saw cut slurry, concrete acid washes and other wastes from entering storm drains Educate Site Personnel!
Trenching and Dewatering Protect spoil piles and trenches open for extended periods Protect stormdrain inlets Know the dewatering treatment methods Educate Site Personnel!
Scheduling and Daily Site Practices Don t schedule work before or during predicted rain and
Erosion and Sediment Control The Rule: If you move it, replace it. If it is damaged, fix it, or report it. Erosion and Sediment Control is 24/7 Rain or Shine
Slow the Water Down Slow the water in swales, gutters, etc. Teach site personnel that open ditches, swales and gutters are not wash-out areas for tools Protect these areas to prevent scour and reduce velocity going into the receiving water.
What s wrong with this picture?
Stormwater Pollution Prevention Everyone s Issue