Alternative Technology

1
Alternative Technology

• Wattle Installation Guide
• Sedimentation Devices
• Erosion Control Products

2
Wattles

• Research stage as substitute for Type B Rock Silt
  Check
• Not currently approved as substitute for silt
  checks
• Selected usage on Trout Waters and other ESAs
• Selected checks will be replaced as shown on
  plans or directed by Engineer
• Involve application of chemical polymer to aid in
  turbidity reduction of project runoff

3
Wattle Installation Guide
Wattle
Road
Erosion Control Blanket
The Basics Simply fit the wattle across the
ditch with some erosion control blanket beneath
it.
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Sprinkle 100 grams of PAM over the lower center
portion of the wattle prior to rain event
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Typical Installation Materials
Metal sod staples and mallet
Erosion control blanket
24 long wooden stakes
Close up of the mesh
wattle
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Installation Guide

• Place erosion control matting as splash pad
• 1/3 upslope and under wattle with remaining
  2/3 down slope
• Staple edges and interior at 1 ft spacing staple
  interior of matting in offset rows

• Place wooden stakes to secure wattle to ground
  contour and to prevent from dislodging in
  large/intense rain events
• 4 wooden stakes on down slope side angle
  upslope
• 2 wooden stakes on upslope side angle down slope

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Installation Guide
Is there a gap at the upturned edge of the wattle?
Weave wire staples through mesh at an angle to
the wattle-space every 1 ft.
Fill gaps with excess fabric
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100 grams PAM
Sprinkle 100 grams of PAM 705 on the lower,
center portion of the wattle where water is going
to flow over.
Between here and here
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Polyacrylamide (PAM)

• Water soluble synthetic polymer
• Forms dry powder, solution, emulsion, logs

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North Carolina PAM List

• The following PAMs are approved for use in NC for
  dosing turbid water

• Applied Polymer Systems APS 705
• Applied Polymer Systems APS 712
• Applied Polymer Systems APS 730
• Applied Polymer Systems APS 740
• Also 3 solid blocks are approved
• Requires a settling basin or sediment bag after
  dosing.
• http//h2o.enr.state.nc.us/ws/documents/pams_list.
  pdf

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Flocculation by PAM

• PAM binds (or flocculates) suspended sediment by
  attaching to several soil particles forming a
  larger aggregate or floc.

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Flocculation by PAM

• The larger (and now heavier) flocs then settle
  out of suspension.

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Flocculation!
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Experimental Results
Site 1
Site 2
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Recommended Wattle Spacing (ft)
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Sedimentation Devices Rigid inlet protection

• Consists of a plastic dome cover that installs
  over concrete drainage box.
• A custom spun-web polyester cover is added and
  secured with 57/5 stone in manufacturer
  provided pockets to hold in place.

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Sedimentation Devices Belted Silt Fence

• Consists of spun-web polyester material with a
  fiberglass netting woven into the fabric
  providing increased strength
• Use only metal t-post for NCDOT projects

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Erosion Control Products Fiber Reinforced Matrix

• Hydraulically applied wood fiber mulch with
  cross-linked synthetic fibers and other additives
  to provide a flexible erosion control blanket.
• Application rate 3,000-4,000 lb/ac
• Substitute for Straw or Excelsior Matting at
  direction of Engineer

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Erosion Control Products Fiber Reinforced Matrix

• Hydraulically applied cotton fiber mulch that
  contains all natural components
• Application Rate 3,000-4,000 lb/ac
• Substitute for Straw or Excelsior Matting at
  direction of Engineer