216.01 216-1 SECTION 216 SOIL RETENTION COVERING DESCRIPTION
216.01 This work consists of furnishing, preparing, applying, placing, and securing soil retention
blankets and turf reinforcement mats for erosion control on roadway slopes or channels as designated in the Contract. MATERIALS
216.02 Soil retention covering shall be either a soil retention blanket or a turf reinforcement
mat as specified in the Contract. It shall be one of the products listed on CDOT’s Approved Products List and shall conform to the following:
a.Soil Retention Blanket . Soil retention blanket shall be composed of degradable natural fibers mechanically bound together between two slowly degrading synthetic or natural fiber nettings to form a continuous matrix and shall conform to the requirements of Tables 216 -1 and 216- 2. The blanket shall be of consistent thickness with the fiber evenly distributed over the entire area of the mat. When specified, lightweight polypropylene netting shall be 1.5 pounds per 1 ,000 square feet; heavyweight netting shall be 2.9 pounds per 1 ,000 square feet. When biodegradable blanket is specified, the thread shall be 100 percent biodegradable; polypropylene thread is not allowed. When photodegradable netting is specified, the thread shall be polyester, biodegradable or photodegradable. Blankets and nettings shall be non- toxic to vegetation and shall not inhibit germination of native seed mix as specified in the Contract. The materials shall not be toxic or injurious to humans. Class 1 blanket shall be an extended term blanket with a typ ical 24 -month functional longevity. Class 2 blanket shall be a long -term blanket with a typical 36 -month functional longevity. The class of blanket is defined by the physical and performance characteristics.
b.Soil Retention Blanket (Straw -Coconut). Soil Retention Blanket (Straw -Coconut) shall be a machine- produced mat consisting of 70 percent certified weed free agricultural straw or Colorado native grass straw and 30 percent coconut fiber. The blanket shall be either biodegradable or photodegradable. Blankets shall be sewn together on a maximum 2 -inch centers. Netting shall be as follows: When biodegradable netting is specified, the top and bottom netting shall be 100 percent biodegradable organic jute fiber. Netting shall be constructed using a weave unattached at intersections , which allows the strands of the net to move independently of each other. When photodegradable netting is specified, the bottom side shall be lightweight polypropylene. The top side shall be heavyweight or lightweight polypropylene. 216.02 216-2 (c) Soil Retention Blanket (Excelsior). Soil Retention Blanket (Excelsior) shall consist of a machine- produced mat of 100 percent curled wood excelsior, 80 percent of which shall be 6 inches or longer in fiber length. It shall be either biodegradable or photodegradable. Blankets shall be sewn together at a maximum of 4 -inch centers. Netting shall be as follows: When biodegradable netting is specified, the top and bottom netting shall be 100 percent biodegradable organic jute fiber. Netting shall be constructed using a weave unattached at intersections , which allows the strands of the net to move independently of each other. When photodegradable netting is specified, the bottom side shall be lightweight polypropylene. The top side shall be heavyweight or lightweight polypropylene.
d.Soil Retention Blanket (Coconut). Soil Retention Blanket (Coconut) shall be a machine- produced mat consisting of 100 percent coconut fiber. It shall be either biodegradable or photodegradable. Netting shall be as follows: When biodegradable netting is specified, the top and bottom netting shall be 100 percent biodegradable organic jute fiber. Netting shall be constructed using a weave that is unattached at the intersections, and which allows the strands of the net to move independently of each other. When photodegradable netting is specified, the bottom and top side shall be heavyweight polypropylene. Table 216 -1 PHYSICAL REQUIREMENTS FOR SOIL RETENTION BLANKET – PHOTODEGRADABLE OR BIODEGRADABLE BLANKETS Photo/Bio Degradable Class Minimum Roll Width Minimum Thickness ASTM D6525 Acceptable Matrix Fill Material Min. Mass per Unit Area ASTM 6475 Size of Net Opening Photodegradable Size of Net Opening Bio - degradable 1 6.5 ft 250 mils Straw/ Coconut 8 oz/sy Min. 0.50"x0.50" Max 0.75"x0.75" Min. 0.50"x0.50" Max 0.50"x1.0" 1 6.5 ft 250 mils Excelsior 8 oz/sy Min. 0.50"x0.50" Max 1.0"x2.0" NONE 2 6.5 ft 200 mils Coconut 8 oz/sy Min. 0.50"x0.50" Max 0.75"x0.75" Min. 0.50"x0.50" Max 0.50"x1.0" 216.02 216-3 Table 216 -2 PERFORMANCE REQUIREMENTS FOR SOIL RETENTION BLANKET – PHOTODEGRADABLE OR BIODEGRADABLE BLANKETS Photo/Bio Degradable Class Slope Application “C” Factor1 ASTM D6459 Minimum Tensile Strength MD2 ASTM D6818 1 < 0.10 at 3:1 8.33 lbs./in 2 < 0.10 at 3:1 10.42 lbs./in Table 216 -2 Notes: “C” Factor is calculated as ratio of soil loss from soil retention blanket protected slope (tested at specified or greater gradient, 3H:1V) to ratio of soil loss from unprotected (control) plot in large - scale testing. MD is for machine direction testing (along the length of the roll). Blankets shall be tested for physical properties and have published data from an independent testing facility. Large scale testing of Slope Erosion Protection (“C” factor) shall be performed by an independent testing facility.
e.Turf Reinforcement Mat . Turf reinforcement mat (TRM) shall be a rolled mat consisting of UV stabilized, corrosion resistant , non -degradable synthetic fibers, filaments, or nets processed into a permanent three- dimensional matrix of the thickness specified in Tables 216-3 and 216- 4. TRMs shall provide sufficient thickness, strength, and void space to permit soil filling and retention, and the development of vegetation within the matrix. The class of TRM is defined by the physical and performance characteristics as specified in the following tables. 216.02 216-4 Table 216 -3 PHYSICAL REQUIREMENTS FOR TURF REINFORCEMENT MAT Product Class Minimum Roll Width Minimum Thickness ASTM D6525 Acceptable Matrix Fill Material2 Size of Net Opening2 1 6.5 ft 250 mils Excelsior , Straw/Coconut, Coconut, or Polymer fibers Minimum: 0.50"x0.50" Maximum: 0.75"x0.75" 2 6.5 ft 250 mils 100% UV Stabilized Synthetic or Coconut Fibers Maximum 0.50"x 0.50" 3 6.5 ft 250 mils 100% UV Stabilized Synthetic Fibers Maximum 0.50"x 0.50" Table 216 -3 Notes: For TRMs containing degradable components, all property values shall be obtained on the non- degradable portion of the matting alone. For TRMs with nets and fill material. Netted TRMs shall be sewn together on a maximum 2 -inch centers. Table 216 -4 PERFORMANCE REQUIREMENTS FOR TURF REINFORCEMENT MAT Product Class Tensile Strength MD ASTM D6818 Minimum UV Stability at 500 Hours ASTM D4355 Minimum Permissible Shear Stress* (Unvegetated) ASTM D6460 1 125 lb/ft 80% 1.8 lb/sf 2 150 lb/ft 80% 2.5 lb/sf 3 175 lb/ft 80% 3.1 lb/sf Table 216 -4 Notes: * Permissible shear stress is the minimum shear stress that a product must be able to sustain when placed on a channel un- vegetated without physical damage or excess soil loss. Failure is defined as 1/2 inch of soil loss during a 30 -minute flow event in large scale testing. 216.03 216-5 TRMs shall be tested for physical properties and have published data from an independent testing facility. Large scale testing of Permissible Shear Stress shall be performed by an independent testing facility.
f.Staples . Staples shall be made of ductile steel wire , 0.165 inches in diameter, 8 inches long and have a 1 -inch crown. “T” shaped staples will not be permitted. A sample of the staples and a Certificate of Compliance (COC) including the manufacturer's product data showing that the product meets the Contract requirements shall be submitted for approval at the Environmental Pre- construction Conference. Installation of the blanket will not begin until approval has been received from the Engineer in writing.
g.Earth Anchors. The mechanical earth anchor shall be composed of a load bearing face plate, a tendon rod or wire rope, and a locking head or percussion anchor. Each element of the anchor shall be composed of corrosion resistant materials. The anchor and wire rope shall have a breaking strength of 9,500 pounds utilizing standard tensile testing and ASTM A1007- 07. The anchor shall have a minimum 1,000 pounds’ ultimate holding strength in normal soil and a manufacturer’s recommended 216.03 minimum driven depth of 3.5 feet. A sample of the anchors and a Certificate of Compliance (COC) including the manufacturer's product data showing that the product meets the Contract requirements shall be submitted for approval at the Environmental Pre- construction Conference. Installation of the blanket will not begin until approval has been received from the Engineer in writing. CONSTRUCTION REQUIREMENTS
216.03 The Contractor shall install soil retention coverings per Standard Plan M -216-1 and the
following procedure:
1.Prepare soil per subsection 212.06(a).
2.Apply topsoil or soil conditioning as directed in the Contract to prepare seed bed.
3.Place seed per the Contract.
4.Unroll the covering parallel to the primary direction of flow.
5.Ensure that the covering maintains direct contact with the soil surface over the entirety of the installation area.
6.Do not stretch the material or allow it to bridge over surface inconsistencies.
7.Staple the covering to the soil such that each staple is flush with the underlying soil.
8.Ensure that staples or earth anchors are installed full depth to resist pull out. No bent over staples will be allowed. Install anchor trenches, seams, and terminal ends as shown on the plans. The Contractor shall install TRMs using the following procedure:
1.Place 3 inches of topsoil or soil amended with soil conditioning.
2.Apply half of the specified seed at the broadcast rate and rake it into the soil.
3.Install TRM.
4.Place 1 inch of topsoil or soil amended with soil conditioning into the matrix to fill the product thickness. 216.04 216-6 5. Apply the remaining half of the specified seed at the broadcast rate and rake it into the soil.
6.Install soil retention blanket (Photodegradable or Biodegradable Class 1) over the seeded area and TRM. When applicable, the covering shall be unrolled with the heavyweight polypropylene netting on top and the lightweight polypropylene netting in contact with the soil.
216.04 Slope Application . Soil retention coverings shall be installed on slopes as follows:
The upslope end shall be buried in a trench 3 feet beyond the crest of the slope if possible. Trench depth shall be a minimum of 6 inches unless required by the manufacture to be deeper. Before backfilling begins, staples shall be placed across the widt h of the trench. The trench shall then be backfilled to grade with soil amended with soil conditioning or topsoil, compacted by foot tamping, and seeded. Fabric shall be brought back over trench and secured with staples or earth anchors at 1 foot on center . There shall be an overlap wherever one roll of fabric ends and another begins , with the uphill covering placed on top of the downhill covering. Staples shall be installed in the overlap. There shall be an overlap wherever two widths of covering are applied side by side. Staples shall be installed in the overlap. Staple checks shall be installed on the slope length at a maximum of every 35 feet. Each staple check shall consist of two rows of staggered staples. The down slope end shall be buried in a trench 3 feet beyond the toe of slope. Before backfilling begins, staples shall be placed across the width of the trench. The trench shall then be backfilled to grade with soil amended with soil conditioning or topso il, compacted by foot tamping, and seeded. Fabric shall be brought back over the trench and secured with staples or earth anchors. If a slope runs into State waters or cannot be extended 3 feet beyond the toe of slope, the end of covering shall be secured using a staple check as described above. Coverings shall be securely fastened to the soil by installing staples or earth anchors at the minimum rate shown on the Standard Plan M -216-1. Staple or earth anchor spacing shall be reduced where required due to soil type or steepness of slope.
216.05 Channel Application . Soil retention coverings shall be installed as follows on a
channel application: Coverings shall be anchored at the beginning and end of the channel across its entire width by burying the end in a trench. Trench depth shall be a minimum of 6 inches, unless a larger depth is specified by the manufacturer’s recommendations. Before backfilling begins, staples shall be placed across the width of the trench. The trench shall then be backfilled to grade with soil amended with soil conditioning or topsoil and compacted by foot tamping and seeded. Fabric shall be brought back over the trench an d stapled. Covering shall be unrolled in the direction of flow and placed in the bottom of the channel first. Seams shall not be placed down the center of the channel bottom or in areas of concentrated flows when placing rolls side by side. 216.06 216-7 There shall be an overlap wherever one roll of covering ends and another begins with the upstream covering placed on top of the downstream covering. Two rows of staggered staples shall be placed. There shall be an overlap wherever two widths of covering are applied side by side. Staples shall be placed in the overlap. The covering shall have a channel check slot every 30 feet along the gradient of the flowline. Check slots shall extend the entire width of the channel. The covering shall be buried in a trench. Before backfilling begins, staples shall be placed across t he width of the trench. The trench shall then be backfilled to grade with soil amended with soil conditioning or topsoil, compacted by foot tamping, and seeded. Fabric shall be brought back over the trench and continued down the channel. Coverings shall be securely fastened to the soil by installing staples at the minimum rate shown on the plans. Staple spacing shall be reduced where needed due to soil type or high flows.
216.06 Maintenance . The Contractor shall maintain the soil retention coverings until all work
on the Contract has been completed and accepted. Maintenance shall consist of the repair of areas where damage is due to the Contractor’s operations. Maintenance shall be performed at the Contractor’s expense. Repair of those areas damaged by causes not at tributable to the Contractor’s operations shall be repaired by the Contractor and will be paid for at the contract unit price. Areas shall be repaired to reestablish the condition and grade of the soil and seeding before application of the covering. METHOD OF MEASUREMENT
216.07 Soil retention coverings, including staples, complete in place and accepted, will be
measured by the square yard of finished surface, excluding overlap, which is installed and accepted. Earth anchors will be measured by the actual number of earth anchors complete in place and accepted. BASIS OF PAYMENT
216.08 The accepted quantities of soil retention coverings will be paid for at the contract unit
price per square yard. The accepted quantities of earth anchors will be paid for at the contract unit price for each installed. Payment will be made under: Pay Item Pay Unit Soil Retention Blanket (_) (Photodegradable Class _) Square Yard Soil Retention Blanket (_ ) (Biodegradable Class _) Square Yard Turf Reinforcement Mat (Class _) Square Yard Earth Anchors Each Preparation of seedbed, fertilizing, and seeding will be measured and paid for per Section 212. 216-8 Placing and preparation of seedbed, fertilizing, and seeding of soil under the TRM layer will be measured and paid for per Section 212. Topsoil or amended soil and seed placed on the TRM will be measured and paid for per Sections 207 and 212. Staples will not be measured and paid for separately but shall be included in the work. 217.01 217-1 SECTION 217 HERBICIDE TREATMENT DESCRIPTION
217.01 This work consists of furnishing and applying herbicides to prevent or control plant
growth in areas shown on the plans or designated. MATERIALS
217.02 Herbicides shall be designated in the contract.
All herbicide labels shall be currently registered with the Colorado Department of Agriculture and the U.S. Environmental Protection Agency . All herbicides shall be supplied to the project in labeled containers. The labels shall show the product name, chemical composition, expiration date, and directions for use. CONSTRUCTION REQUIREMENTS
217.03 All herbicides shall be applied by commercial pesticide applicators licensed by the
Colorado Department of Agriculture as qualified applicators. The Contractor shall furnish documentation of such licensing before herbicide application. Herbicide mixing and application shall be done per instructions on the registered product label. The Engineer shall be furnished such label information before mixing and application. The Contractor shall notify the Engineer at least 24 hours before each herbicide application and shall indicate the time and location application will begin. Application will not be allowed on Saturdays, Sundays, or holidays unless otherwise approved by the Engineer. Herbicides shall not be applied when weather conditions, including wind conditions, are unsuitable for such work. Herbicides shall not be applied when soil is extremely dry. Herbicide application method shall be such that plant growth outside the designated treatment areas will not be damaged. All damage caused by improper herbicide application shall be repaired at the Contractor's expense. Herbicides shall not be used on areas that are to be topsoil sources unless otherwise approved by the Engineer. METHOD OF MEASUREMENT
217.04 The quantity of herbicide treatment to be measured will be the actual number of
square yards treated per the foregoing requirements or the actual number of hours the Contractor spends applying the herbicide and accepted by the Engineer. Areas designated to receive herbicide treatment will be measured once for each designated application. Reapplication of her bicide required due to inappropriate timing of the original application will not be measured or paid for.
Source: Colorado Standard Specifications for Road and Bridge Construction, 2023 Edition. Pages 307–314 of 943.