V. Criteria
This section establishes the minimum allowable standards for design, installation and performance requirements. Only Wisconsin Department of Transportation (WisDOT) Erosion Control Product Acceptability List (PAL) approved mats will be accepted for use in this standard.
Slope and slope length shall be taken into consideration. This information can be found in the Slope Erosion Control Matrix located in the PAL.
To differentiate applications Erosion mats are organized into three Classes of mats, which are further broken down into various Types.
A. Class I: A short-term duration (minimum of 6 months), light duty, organic mat with photodegradable plastic or biodegradable netting.
1. Type A – Use on erodible slopes 2.5:1 or flatter.
2. Type B – Double netted product for use on erodible slopes 2:1 or flatter.
B. Class I, Urban: A short-term duration (minimum of 6 months), light duty, organic erosion control mat for areas where mowing may be accomplished within two weeks after installation.
1. Urban, Type A – Use on erodible soils with slopes 4:1 or flatter.
2. Urban, Type B – A double netted product for use on slopes 2.5:1 or flatter.
C. Class II: A long-term duration (three years or greater), organic erosion control revegetative mat.
1. Type A – Jute fiber only for use on slopes 2:1 or flatter for sod reinforcement.
2. Type B – For use on slopes 2:1 or greater made with plastic or biodegradable net.
3. Type C – A woven mat of 100% organic fibers for use on slopes 2:1 or flatter and in environmentally and biologically sensitive areas where plastic netting is inappropriate.
D. Class III: A permanent 100% synthetic ECRM or TRM. Either a soil stabilizer Type A or Class I, Type A or B erosion mat must be placed over the soil filled TRM.
1. Type A – An ECRM for use on slopes 2:1 or flatter.
2. Type B or C – A TRM for use on slopes 2:1 or flatter.
3. Type D – A TRM for use on slopes 1:1 or flatter.
E. Material Selection
1. For mats that utilize netting, the netting shall be bonded to the parent material to prevent separation of the net for the life of the product.
2. For urban class mats the following material requirements shall be adhered to:
a. Only 100% organic biodegradable netted products are allowed, including parent material, stitching, and netting.
b. The netting shall be stitched with biodegradable thread/yarn to prevent separation of the net from parent material.
c. All materials and additive components used to manufacture the anchoring devices shall be completely biodegradable as determined by ASTM D 5338.
d. Mats with photodegradable netting shall not be installed after September 1st.
F. Installation
1. ECRMs shall be installed after all topsoiling, fertilizing, liming and seeding is complete.
2. The mat shall be in firm and intimate contact with the soil. It shall be installed and anchored per the manufacturer's recommendation.
3. TRM shall be installed in conjunction with the topsoiling operation and shall be followed by ECRM installation.
4. At time of installation, document the manufacturer and mat type by retention of material labels and manufacturer's installation instructions. Retain this documentation until the site has been stabilized.
VI. Considerations
A. Urban mats may be used in lieu of sod.
B. Documentation of materials used, monitoring logs, project diary and weekly inspection forms, including erosion and stormwater management plans, should be turned over to the authority charged with long term maintenance of the site.
VII. Plans and Specifications
A. Plans and specifications for installing erosion mat shall be in keeping with this standard and shall describe the requirements for applying the practice to achieve its intended purpose. The plans and specifications shall address the following:
1. Location of erosion mat
2. Installation Sequence
3. Material specification conforming to standard
B. All plans, standard detail drawings, or specifications shall include schedule for installation, inspection, and maintenance. The responsible party shall be identified.
VIII. Operation and Maintenance
A. Erosion mat 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.
B. If there are signs of rilling under the mat, install more staples or more frequent anchoring trenches. If rilling becomes severe enough to prevent establishment of vegetation, remove the section of mat where the damage has occurred. Fill the eroded area with topsoil, compact, reseed and replace the section of mat, trenching and overlapping ends per manufacturer's recommendations. Additional staking is recommended near where rilling was filled.
C. If the reinforcing plastic netting has separated from the mat, remove the plastic and if necessary replace the mat.
D. Maintenance shall be completed as soon as possible with consideration to site conditions.
IX. References
X. Definitions
Sheet and Rill Erosion (II): Sheet and rill erosion is the removal of soil by the action of rainfall and shallow overland runoff. It is the first stage in water erosion. As flow becomes more concentrated rills occur. As soil detachment continues or flow increases, rills will become wider and deeper forming gullies.
Erosion Control Revegetative Mats (ECRM) (II): Erosion control revegetative mats are designed to be placed on the soil surface.
Turf-Reinforcement Mats (TRM) (II): Turf-reinforcement mats are permanent devices constructed from various types of synthetic materials and buried below the surface to help stabilize the soil. TRMs must be used in conjunction with an ECRM or an approved Type A soil stabilizer.
Sediment Bale Barrier
(Non-Channel)
1055 (08/03)
Wisconsin Department of Natural Resources
Conservation Practice Standard
Note: Words in the standard that are shown in italics are described in IX. Definitions. The words are italicized the first time they are used.
I. Definition
A temporary sediment barrier consisting of a row of entrenched and anchored straw bales, hay bales or equivalent material used to intercept sediment-laden sheet flow from small drainage 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 where:
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. Effectiveness is required for less than 3 months.
4. Conditions allow for the bales to be properly entrenched and staked as outlined in the Criteria Section V.
B. Under no circumstance shall sediment bale barriers 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 sediment bale barriers 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 the sediment bale barrier. 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. At a minimum, sediment bale barriers shall be placed in a single row, lengthwise on the contour, with the ends of adjacent sediment bale barriers tightly abutting one another. The holes between bales shall be chinked (filled by wedging) with straw, hay or equivalent material to prevent water from escaping between the bales.
2. The maximum allowable slope lengths contributing runoff to a sediment bale barrier are specified in Table 1.
3. Sediment bale barriers shall not be placed perpendicular to the contour.
4. The end of the sediment bale barrier shall be extended upslope to prevent water from flowing around the barrier ends.
B. Height – Installed sediment bale barrier shall be a minimum of 10 inches high and shall not exceed a maximum height of 20 inches from ground level.
C. Anchoring and Support
1. The barrier shall be entrenched and backfilled. A trench shall be excavated the width of a sediment bale barrier and the length of the proposed barrier to a minimum depth of 4 inches. After bales are staked and chinked, the excavated soil shall be backfilled and compacted against the barrier. Backfill to ground level on the down slope side. On the upslope side of the sediment bale barrier backfill to 4 inches above ground level.
2. At least two wood stakes, “T" or “U" steel posts, or ½ inch rebar driven through at equidistance along the centerline of the barrier shall securely anchor each bale. The minimum cross sectional area for wood stakes shall be 2.0 by 2.0 inches nominal. The first stake in each bale shall be driven toward the previously laid bale to force the bales together. Stakes shall be driven a minimum 12-inches into the ground to securely anchor the sediment bale barriers.
3. Bales shall be installed so that bindings are oriented around the sides rather than along the tops and bottoms of the bales in order to prevent deterioration of the bindings.
VI. Considerations
A. Improper placement as well as improper installation and maintenance of sediment bale barriers will significantly decrease the effectiveness of this practice.
B. Sediment bale barriers should not be used upslope of the disturbed area.
C. A double row of sediment bale barriers may be installed in areas where additional protection is needed.
D. For safety, place all anchoring flush with the sediment bale barrier or cap any exposed anchoring device.
