A. Consider seeding at a lower rate and making two passes to ensure adequate coverage.
B. Compacted soil areas may need special site preparation prior to seeding to mitigate compaction. This may be accomplished by chisel plowing to a depth of 12 inches along the contour after heavy equipment has left the site.
C. Sod may be considered where adequate watering is available.
D.
When working in riparian areas refer to the NRCS Engineering Field Handbook, Chapter
16, Streambank and Shoreline Protection and Chapter
18,
Soil Bioengineering for Upland Slope Protection and Erosion Reduction.
E. A site assessment should be conducted to evaluate soil characteristics, topography, exposure to sunlight, proximity to natural plant communities, proximity to nuisance, noxious and/or invasive species, site history, moisture regime, climatic patterns, soil fertility, and previous herbicide applications.
F. Use introduced species only in places where they will not spread into existing natural areas.
G. Lightly roll or compact the area using suitable equipment when the seedbed is judged to be too loose, or if the seedbed contains clods that might reduce seed germination.
H. See Section IX. References for suggested seed mixes (NRCS, WisDOT, UWEX) or use their equivalent.
I. Turf seedlings should not be mowed until the stand is at least 6 inches tall. Do not mow closer than 3 inches during the first year of establishment.
J. Seeding should not be done when the soil is too wet.
K. Consider watering to help establish the seed. Water application rates shall be controlled to prevent runoff and erosion.
L. Prairie plants may not effectively provide erosion control during their establishment period without a nurse crop.
M. Topsoil originating from agricultural fields may contain residual chemicals. The seedbed should be free of residual herbicide or other contaminants that will prevent establishment and maintenance of vegetation. Testing for soil contaminants may be appropriate if there is doubt concerning the soil's quality.
N. Consider using mulch or a nurse crop if selected species are not intended for quick germination. When mulching refer to WDNR Conservation Practice Standard Mulching for Construction Sites (1058).
VIl. Plans and Specifications
Plans and specifications for seeding shall be in keeping with this standard and shall describe the requirements for applying this practice.
All plans, standard detail drawings, or specifications shall include schedule for installation, inspection, and maintenance. The responsible party shall be identified.
VlIl. Operation and Maintenance
A. During construction areas that have been seeded shall at a minimum be inspected weekly and within 24 hours after every precipitation event that produces 0.5 inches of rain or more during a 24-hour period. Inspect weekly during the growing season until vegetation is densely established or permit expires. Repair and reseed areas that have erosion damage as necessary.
B. Limit vehicle traffic and other forms of compaction in areas that are seeded.
C. A fertilizer program should begin with a soil test. Soil tests provide specific fertilizer recommendations for the site and can help to avoid over-application of fertilizers.
IX. References
A. Seed Selection References
United States Department of Agriculture – Natural Resource Conservation Service Field Office Technical Guide Section IV, Standard 342, Critical Area Planting.
UWEX Publication A3434 Lawn and Establishment & Renovation.
WisDOT, 2003. State of Wisconsin Standard Specifications For Highway and Structure Construction. Section 630, Seeding.
B. General References
Metropolitan Council, 2003. Urban Small Sites Best Management Practice Manual, Chapter
3, Vegetative Methods 3-85 – 3-91. Minneapolis.
The State of Wisconsin list of noxious weeds can be found in Statute 66.0407.
United States Department of Agriculture – Natural Resources Conservation Service. Engineering Field Handbook, Chapters
16 and
18.
UWEX Publication GWQ002 Lawn & Garden Fertilizers.
X. Definitions
Dense (V.A.2.b) A stand of 3-inch high grassy vegetation that uniformly covers at least 70% of a representative 1 square yard plot.
Dormant seed (V.B.4): Seed is applied after climatic conditions prevent germination until the following spring.
Introduced Species (VI.F) Plant species that historically would not have been found in North America until they were brought here by travelers from other parts of the world. This would include smooth bromegrass and alfalfa. Some of these species may have a wide distribution such as Kentucky bluegrass.
Nurse Crop (V.B.2.b): Also known as a companion crop; is the application of temporary (annual) seed with permanent seed.
Permanent seeding (II) Seeding designed to minimize erosion for an indefinite period after land disturbing construction activities have ceased on the site.
Soil Bioengineering (VI.D) Practice of combining mechanical, biological and ecological concepts to arrest and prevent shallow slope failures and erosion.
Temporary Seeding (II) Seeding designed to control erosion for a time period of one year or less that is generally removed in order to perform further construction activities or to permanently stabilize a construction site.
Topsoil (V.A.2.a) Consists of loam, sandy loam, silt loam, silty clay or clay loam humus-bearing soils adapted to sustain plant life with a pH range of 5.5 – 8.0. Manufactured topsoil shall through the addition of sand or organic humus material, peat, manure or compost meet the above criteria.
Silt Fence
1056 (03/06)
Wisconsin Department of Natural Resources
Conservation Practice Standard
Note: Words in the standard that are shown in italics are described in X. Definitions. The words are italicized the first time they are used.
I. Definition
Silt fence is a temporary sediment barrier of entrenched permeable geotextile fabric designed to intercept and slow the flow of sediment-laden sheet flow runoff from small areas of disturbed soil.
II. Purpose
The purpose of this practice is to reduce slope length of the disturbed area and to intercept and retain transported sediment from disturbed areas.
III. Conditions Where Practice Applies
A. This standard applies to the following applications:
1. Erosion occurs in the form of sheet and rill erosion1. There is no concentration of water flowing to the barrier
(channel erosion).
2. Where adjacent areas need protection from sediment-laden runoff.
3. Where effectiveness is required for one year or less.
4. Where conditions allow for silt fence to be properly entrenched and staked as outlined in the Criteria Section V.
B. Under no circumstance shall silt fence be used in the following applications:
1. Below the ordinary high watermark or placed perpendicular to flow in streams, swales, ditches or any place where flow is concentrated.
2. Where the maximum gradient upslope of the fence is greater than 50% (2:1).
IV. Federal, State, and Local Laws
Users of this standard shall be aware of applicable federal, state, and local laws, rules, regulations, or permit requirements governing the use and placement of silt fence. This standard does not contain the text of federal, state, or local laws.
V. Criteria
This section establishes the minimum standards for design, installation and performance requirements.
A. Placement
1.
When installed as a stand-alone practice on a slope, silt fence shall be placed on the contour. The parallel spacing shall not exceed the maximum slope lengths for the appropriate slope as specified in Table 1
.
- See PDF for table 
2. Silt fences shall not be placed perpendicular to the contour.
3. The ends of the fence shall be extended upslope to prevent water from flowing around the ends of the fence.
B. Height – Installed silt fences shall be a minimum 14 inches high and shall not exceed 28 inches in height measured from the installed ground elevation.
C. Support – Silt fences shall be supported by either steel or wood supports as specified below:
1. Wood supports
a. The full height of the silt fence shall be supported by 1 1/8 inches by 1 1/8 inches air or kiln dried posts of hickory or oak.
b. The silt fence fabric shall be stapled, using at least 0.5-inch staples, to the upslope side of the posts in at least 3 places.
c. The posts shall be a minimum of 3 feet long for 24-inch silt fence and a minimum of 4 feet for 36-inch silt fence fabric.
2. Steel supports
a. The full height of the silt fence shall be supported by steel posts at least 5 feet long with a strength of 1.33 pounds per foot and have projections for the attachment of fasteners.
b. The silt fence fabric shall be attached in at least three places on the upslope side with 50 pound plastic tie straps or wire fasteners. To prevent damage to the fabric from fastener, the protruding ends shall be pointed away from the fabric.
3. The maximum spacing of posts for non-woven silt fence shall be 3 feet and for woven fabric 8 feet.
4. Silt fence shall have a support cord.
5. Where joints are necessary, each end of the fabric shall be securely fastened to a post. The posts shall then be wrapped around each other to produce a stable, secure joint or shall be overlapped the distance between two posts.
6. A minimum of 20 inches of the post shall extend into the ground after installation.
D. Anchoring – Silt fence shall be anchored by spreading at least 8 inches of the fabric in a 4 inch wide by 6 inch deep trench, or 6 inch deep V-trench on the upslope side of the fence. The trench shall be backfilled and compacted. Trenches shall not be excavated wider and deeper than necessary for proper installation.
On the terminal ends of silt fence the fabric shall be wrapped around the post such that the staples are not visible.
E.
Geotextile Fabric Specifications – The geotextile fabric consists of either woven or non-woven polyester, polypropylene, stabilized nylon, polyethylene, or polyvinylidene chloride. Non-woven fabric may be needle punched, heat bonded, resin bonded, or combinations thereof. All fabric shall meet the following requirements as specified in Table 2.
-
See PDF for table
(WisDOT Standard Specifications for Road and Bridge Construction, 2001)
1 All numerical values represent minimum / maximum average roll values. (For example, the average minimum test
results on any roll in a lot should meet or exceed the minimum specified values.)
Silt fence shall have a maximum flow rate of 10-gallons/minute/square foot at 50mm constant head as determined by multiplying permittivity in 1/second as determined by ASTM D-4491 by a conversion factor of 74.
F. Removal – Silt fences shall be removed once the disturbed area is permanently stabilized and no longer susceptible to erosion.
VI. Considerations
A. Improper placement as well as improper installation and maintenance of silt fences will significantly decrease the effectiveness of this practice.
