U.S. Fence

Typical Details for Silt Fence Construction

1 Dig a small toe-in trench along the line where Silt Fence is to be placed. The trench should be a minimum of 6 inches deep and 6 inches wide. Place the excavated material on the front or upstream side of the trench to facilitate backfilling later.

2 Drive the fence posts into the back or downstream side of the trench. The posts should be driven so that at least 1/3 of the height of the post is in the ground. When installing a pre-fabricated Silt Fence with fabric attached to the posts, the posts should be driven so that at least 6 inches of fabric will be buried in the ground. Place posts between 2 feet and 10 feet apart depending on the anticipated volume of sediment runoff at the site. Most Pre-fabricated Silt Fence have posts spaced approximately 7 to 10 feet apart, which is usually adequate. If there is a low spot where most sediments tend to collect, closer spacing may be required and pre-fabricated Silt Fence can be backed up with extra posts. Posts constructed of hardwood or metal with sufficient strength to support a full load of deposited sediment are recommended.

3 If pre-fabricated Silt Fence is not being used the fabric must be attached to the posts. Depending on the type of fabric used, different methods of attachment are recommended. If using a fabric with sewn pockets, insert the posts into the pockets before driving them to ensure proper fit and spacing. Fabrics with a reinforcing cord sewn in the top hem should be slit in the hem at the location of the post. Be sure not to slit the cord. Pull cord out slightly (approximately 4 to 6 inches), twist into a loop and place tightly over the top of the post. Make the loop so that tension on the Silt Fence will tighten the loop around the post.

4 Backfill the trench with the excavated material and tamp down so that at least 6 inches of the fabric is securely toed into the ground to prevent under-mining.

5 Check Silt Fences periodically, especially after rainfall. Large build ups of sediment must be removed so that the Silt Fence can continue to function as intended. As an alternative, an additional row of Silt Fence may be installed up slope from the initial row.

The resistance of woven geotextiles to ultraviolet light depends primarily on the antioxidant and carbon black package mixes with the resin to prepare a formulation for monofilament extrusion. As long as this formulation does not change, the UV characteristics do not change, and hence Tenax only physically tests this once per formulation.

As indicated in the specification Tenax tests per ASTM D4355; meeting or exceeding a value of 70% retained after 500 hours of UV exposure.

Although Tenax sources some of the best woven geotextiles using the best available antioxidant packages, please note that strength values indicated in the specification are ony 70% retained after 500 hours or 21 days of UV exposure. And hence Tenax Corporation can only warrant those materials for this time period. This recommendation is based on UV performance data published in technical literature indicating geotextile strength can decrease sharply after prolonged exposure to sunlight.

Please check with your local state regulatory agencies to verify approval before supplying this product on a DOT project.

RETURN TO SILT FENCE PRODUCT PAGE