NCG020925_James Cahoon Mine - Cahoon Sediment Fence_20180220

Sediment Fence (Silt Fence) Construction Details:
Practice Standards and Specifications 6.62
James Cahoon Mine
US 64 East, Columbia, NC
Tyrrell County

A temporary permeable barrier erected on small disturbed areas to capture sediment from sheet flow. It is made of
filter fabric buried at the bottom, stretched and supported by steel posts.
Planning: Silt fence will be installed along the perimeter of a 12ft wide access road when crossing wetland areas.
Narrow width of fenced area will allow only shallow pools to form behind fence while promoting deposition of sediment
and preventing sedimentation into adjacent wetlands. Ends of fence will be curled uphill in “J” pattern to prevent end
flow. Stabilized outlets will be provided to protect the fence system and release storm flow that exceeds the design.
Design considerations: Silt fence will be constructed of extra-strength synthetic filter fabric. Height of fence will not
exceed 2 feet above natural ground level, and will be constructed from a continuous roll to minimize joints. All joints
will be fastened at a support post with 4 feet minimum of overlap. Extra-strength filter fabric will be fastened to road
side of steel posts (installed 2 feet deep) every 6 feet (every 8 feet if using standard strength filter fabric with wire mesh
backing) and fastened with wire ties. Trench will be excavated along inside of fence approximately 4 inches wide by 8
inches deep, into which 12 inches of fabric will be placed along the bottom and side of the trench. Trench will be
backfilled and compacted.
Maintenance: Inspect sediment fence every week and after each rainfall. Make any required repairs immediately.
Replace any collapsed, damaged, or decomposed fence promptly. Remove all fencing materials and unstable sediment
deposits and bring the area to grade and stabilize it after the contributing drainage area has been properly stabilized.

Ken Elliott, consulting
January 28, 2018