Mulch shall be free of diseased plant residue (i.e. oak wilt), noxious weed seeds, harmful chemical residues, heavy metals, hydrocarbons and other known environmental toxicants.
Marsh hay shall not be used as mulch in lowland areas but may be used on upland sites to prevent the spread of invasive, non-native species (i.e. reed canary grass) commonly found in marsh hay.
Straw and hay mulch that will be crimped shall have a minimum fiber length of 6 inches.
Wood chips or wood bark shall only be used for sites that are not seeded.
C. Application Rate:
1. Mulch shall cover a minimum of 80% of the soil surface for unseeded areas. For seeded areas, mulch shall be placed loose and open enough to allow some sunlight to penetrate and air to circulate but still cover a minimum of 70% of the soil surface.
2. Mulch shall be applied at a uniform rate of 1½ to 2 tons per acre for sites that are seeded, and 2 to 3 tons per acre for sites that are not seeded. This application results in a layer of ½ to 1½ inches thick for seeded sites, and 1½ to 3 inches thick for sites not seeded.
3. Wood chips or wood bark shall be applied at a rate of 6 to 9 tons per acre to achieve a minimum of 80% ground cover. This application should result in a layer of wood chips or wood bark ½ to 1½ inches thick.
D. Mulch Anchoring Methods
Anchoring of mulch shall be based on the type of mulch applied, site conditions, and accomplished by one of the following techniques:
1. Crimping
Immediately after spreading, the mulch shall be anchored by a mulch crimper or equivalent device consisting of a series of dull flat discs with notched edges spaced approximately 8 inches apart. The mulch shall be impressed in the soil to a depth of 1 to 3 inches.
2. Polypropylene Plastic, or Biodegradable Netting
Apply plastic netting over mulch application and staple according to manufacturer's recommendations.
3. Tackifier
Tackifier shall be sprayed in conjunction with mulch or immediately after the mulch has been placed. Tackifiers must be selected from those that meet the WisDOT Erosion Control Product Acceptability List (PAL). Asphalt based products shall not be applied.
The tackifiers shall be applied at the following minimum application rates per acre:
a. Latex-Base: mix 15 gallons of adhesive (or the manufacturer's recommended rate which ever is greater) and a minimum of 250 pounds of recycled newsprint (pulp) as a tracer with 375 gallons of water.
b. Guar Gum: mix 50 pounds of dry adhesive (or the manufacturer's recommended rate which ever is greater) and a minimum of 250 pounds of recycled newsprint (pulp) as tracer with 1,300 gallons of water.
c. Other Tackifiers: (Hydrophilic Polymers) mix 100 pounds of dry adhesive (or the manufacturer's recommended rate which ever is greater) and a minimum of 250 pounds of recycled newsprint (pulp) as a tracer with 1,300 gallons of water.
VI. Considerations
A. Wood products typically absorb available soil nitrogen as they degrade, thus making it unavailable for seed.
B. The use of mulch behind curb and gutter may not be desirable unless anchored by netting, because air turbulence from nearby traffic can displace the mulch. Consider the use of erosion mat or sod as an alternative.
C. In areas where lawn type turf will be established, the use of tackifiers is the preferred anchoring method. Crimping will tend to leave an uneven surface and plastic netting can become displaced and entangled in mowing equipment.
D. A heavier application of mulch may be desired to prevent seedlings from being damaged by frost.
E. It may be beneficial to apply polyacrylimide in addition to mulch. Refer to WDNR Conservation Practice Standard (1050) Erosion Control Land Application of Anionic Polyacrylamide for information about the advantages and proper use of polymers.
F. Concentrated flows above the site where mulch is applied should be diverted.
G. Mulch should be placed within 24 hours of seeding.
H. Mulching operations should not be performed during periods of excessively high winds that would preclude the proper placement of mulch.
I. Materials such as gravel may be effective for erosion control but are not considered mulches.
VII. Plans and Specifications
A. Plans and specifications for mulching 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. Type of mulch used
2. Application rate
3. Timing of application
4. Method of anchoring
B. All plans, standard detail drawings, or specifications shall include schedules for installation, inspection, and maintenance. The responsible party shall be identified.
VIII. Operation and Maintenance
Mulch 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.
Mulch that is displaced shall be reapplied and properly anchored. Maintenance shall be completed as soon as possible with consideration to site conditions.
IX. References
X. Definitions
Noxious weed (V.B): Any weed a governing body declares to be noxious within its respective boundaries. The State of Wisconsin list of noxious weeds can be found in s.
66.0407, Stats.
Solid Waste Byproducts (V.B): Includes industrial, commercial, residential, and agricultural wastes that have been processed, incinerated, or composted and still contain inorganic wastes such as glass and metals and organic wastes including plastics, textiles, rubber, leather, and other miscellaneous organic wastes which may be toxic or hazardous in nature.
Non-Channel Erosion Mat
1052 (08/03)
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
A protective soil cover made of straw, wood, coconut fiber or other suitable plant residue, or plastic fibers formed into a mat, usually with a plastic or biodegradable mesh on one or both sides. Erosion mats are rolled products available in many varieties and combinations of material and with varying life spans.
II. Purpose
The purpose of this practice is to protect the soil surface from the erosive effect of rainfall and prevent sheet erosion
1 during the establishment of grass or other vegetation, and to reduce soil moisture loss due to evaporation. This practice applies to both Erosion Control Revegetative Mats (ECRM) and
Turf-Reinforcement Mats (TRM).
III. Conditions Where Practice Applies
This standard applies to erosion mat selection for use on erodible slopes.
This standard is not for channel erosion; for channel applications reference WDNR Conservation Practice Standard (1053) Channel Erosion Mat.
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 erosion mat. This standard does not contain the text of federal, state, or local laws.
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.
