Replacing Hard Armor with Reinforced Vegetative Solutions Presented by Rob Lawson, CPESC
North Atlantic Region Manager
Rolled Sediment Revetment
Ease of Access – Owner’s Expectations
Overkill?
How do you define Permissible Shear Stress
▪ Shear Stress or “tractive force” is the energy exerted on the lining of the channel or slope
▪ Measured in pounds per square foot (lbs./ft2)
▪ What affects Shear Stress:
▪ Velocity
▪ Depth of flow
▪ Gradient
▪ ASTM industry testing, FHWA, ECTC and NTPEP use this methodology
▪ What is the threshold:
o Industry product testing performed uses a half inch of soil loss as failure criteria
o Once failure has been reached, that will be the permissible shear value allowed for that product
Composite-TRMs
3-D permanent matting structure with fiber matrix
▪ Immediate erosion control
▪ Surface applied: No Soil Filling
▪ Mulching aspect enhances vegetation establishment
▪ Permanently reinforces & anchors roots & stems
▪ Enables vegetation use in severe applications
▪ Substantial cost savings compared to riprap or concrete
Composite Turf Reinforcement Mats
EPA Tech Sheet - Turf Reinforcement Mats (TRMs)
TRMS are classified as a “soft engineering practice,” in contrast to concrete and riprap, which they may replace in certain erosion control situations.
TRMS can incorporate natural fiber materials to assist in establishing vegetation. However, the permanent reinforcement structure of TRMs is composed of entirely non-degradable synthetic materials.
Rip Rap Issues
• Thermal Pollution
• Large Stone – Big Equipment
• Availability
• Installation
• Safety/Liability
• Cost
• Maintenance
• OWNER EXPECTATIONS*Aesthetics, access, etc.
August 2, 2016
We wanted to let you know of changes coming from the U. S. Army Corps of Engineers
(USACE) that could mean big differences in the way Americans protect streambanks and
shorelines from the erosive forces of water. The USACE is trying to encourage everyone to
reduce the amount of Hard Armor (riprap, concrete, and bulkheads) previously used as erosion
control Best Management Practices (BMPs). Hard Armor erosion control measures have not
proven to be permanent fixes for erosion problems around streams, lakes, and the ocean/land
interface. They feel that the only permanent erosion control BMP utilizes vegetation.
The Corps seems to understand there are highly erodible areas where the ocean and land
meet (beaches, bluffs, or tidal areas) may still require use of hard armor (riprap) combined with
vegetation to control erosion. However, you will find soon that the main recommended
stabilization measure favored by the USACE will be vegetation. The Corps will increase support
requirements for what they call Living Islands or Living Shorelines. The Alabama
Department of Environmental Management (ADEM) currently regulates Living Shorelines and
Living Islands under the General Permit ALG10-2011. However, the proposed USACE 2017
Construction General Permit (CGP), the Corps is expanding their emphasis on the use of
“Green Bioengineering” erosion control requirements.
This could be the dawn of a new era for more natural ways to control erosion called living
shorelines or “Green Bioengineering”. The U. S. Army Corps of Engineers (USACE) has
released for public review its list of Proposed Nationwide Permits that will renew 50-Nationwide
Permits for work in wetlands and other waters that are generally regulated by Section 4040 of
the Clean Water Act and/or Section 10of the Rivers and Harbors act of 1899. The USACE also
proposes to issue two Nationwide Permits including a proposed permit that specifically
addresses the construction and maintaining Living Shorelines.
Nationwide Permit B is the Corps’ first living shorelines permit. Living shoreline projects use
various structural and organic materials, such a plants, submerged aquatic vegetation, oyster
shells and stone. For years, permitting guidelines for living shorelines simply were folded into
other rules governing shoreline stabilization methods under Permit 13.
The Corps issues nationwide permits for a whole host of activities covered by the federal Clean
Water and Rivers and Harbors acts. The Corps streamlined review of applications for such
permits because the activities will have minimal effects on the environment.
The new living shoreline permit has been a long time coming, proponents say, as research has
mounted in support of the practical and environmental benefits of this shoreline erosion control
technique. Permit B further legitimizes living shorelines, raising awareness of this shore
stabilization alternative at the federal level.
More importantly, proponents say, the new permit will help speed up the permitting process for
living “vegetated” shorelines and should more evenly balance agency review times for living
shorelines and hardened erosion control structures, such as bulkheads.
The Corps cannot mandate one specific approach to shoreline stabilization, but the agency
does acknowledge the benefits of living shorelines. “We are trying to provide as much
▪ Permanent matting structure reinforces vegetation
▪ Fiber matrix provides immediate erosion control and assists in seed germination/growth
▪ Designed for severe slopes &
drainage channels
Composite Turf Reinforcement Mat (C-TRM)
High Strength Top
Net
3-D Corrugated Center
Net
Straw/Coconut Matrix
Material
High Strength Bottom
Net
Slopes Channels
Straw/coconut fibers provide 2 years of immediate erosion control and mulching
Permissible Shear Stress Values =
Phase 1: Un-vegetated
3.0 lbs/ft2 (144 Pa)
Phase 2: Partially Vegetated
8.0 lbs/ft2 (384 Pa)
Phase 3: Fully Vegetated
10.0 lbs/ft2 (480 Pa)
Comparable to 24 in Rock Rip Rap!
C-TRM Performance
C-TRM Ditches / Slopes
▪ 100% Coconut fiber matrix
▪ Field performance widely documented
▪ Protects soil, seed & root systems from flowing water
C-TRM
Super High Strength
Top Net
3-D Corrugated Center
Net
Coconut Fiber Matrix
Material
Super High Strength
Bottom Net
Slopes
Channels
Shorelines
▪ Coconut Fibers Provide 3 Years of Immediate Erosion Control and Mulching
C-TRM Performance
Permissible Shear Stress Values =
Phase 1 Un-Vegetated3.2 lbs/ft² (153 Pa)
Phase 2: Partially Vegetated10 lbs/ft² (480 Pa)
Phase 3: Fully Vegetated12 lbs/ft² (576 Pa)
Comparable to 30 in Rock Rip Rap!
C-TRM Slope / Channel
C-TRM Shore Line
Polypropylene Matrix Increases Permanent Vegetation Reinforcement
▪ Excellent for shorelines
▪ Replacement for rock and concreteUltra-High Strength
Top Net
3-D Corrugated
Center Net
Polypropylene
Matrix Material
Ultra-High Strength
Bottom Net
Slopes
Channels
Shorelines
Synthetic Composite TRM
Permanent erosion control and mulching, and extended unvegetatedprotection
Permissible Shear Stress Values =
Phase 1: Un-vegetated4.0 lbs/ft² (191 Pa)
Phase 2: Partially Vegetated12 lbs/ft² (574 Pa)
Phase 3: Fully Vegetated14 lbs/ft² (672 Pa)
Comparable to 30 in Rock Rip Rap and some concrete applications!
Synthetic C-TRM Performance
Synthetic Composite TRM Waterways
Synthetic C-TRM Bank Protection
TRM Shear Stress Comparisons
FHWA Specifications
Product FHWA Category
Performance
Requirements
SC-CTRM Type 5. A & B 6 lbs/ft² (288 Pa)
C-CTRM Type 5 A, B & C 8 lbs/ft² (384 Pa)
Synthetic
C-TRMType 5 A, B & C 10 lbs/ft² (480 Pa)
713.18 Permanent Rolled Erosion Control Products
2
3
▪ 60% - 80% Cost Savings vs Rock Riprap (@ $36/sy installed)
▪ One 40 sy roll of Vmax can replace approx 40 tons of rock!
▪ Reduced Long-Term Maintenance
▪ Less Hazardous along Roadways and Pedestrian Areas
▪ Increased stormwater infiltration (LID bioswales/filter strips)
▪ Environmentally Friendly
▪ Ecologically Functional
Why use TRM reinforced vegetation instead of rock?
▪ Up to 60% Savings over rock riprap
▪ Less expensive to install than soil in-filled TRMs
Economic Benefits
Vanderburgh Co Fairgrounds, Evansville IN
Vanderburgh Co Fairgrounds, Evansville IN
2
7 Veterans Park – Talladega, Alabama
Extended-Term Biodegradable
C700BN• 700 gram coir jute netting
• C125BN sewn to bottom
• Cotton thread stitch
Chavis Park Mixture of Bio Solutions
Chavis Park Vegetated
Total cost for a Channel Requiring 30 inch D50 Rock RiprapChannel is 3 ft x 16 ft x 1000 ft
C350 30 inch Rock
Materials $7,800-9,900 $32,000
Labor $6,400-7,900 $21,300
Total Installed
Cost
$14,200-17,800
($8-10/yd²)
$53,300
($30/yd²)
POTENTIAL SAVINGS = $39,100
*Costs will vary depending on location
Economic Benefits
▪ Tested to greater than 5000 lbs/ft tensile strength
▪ Increased geotechnical stability for shallow-slope failures when used in conjunction with percussion driven earth anchors
▪ High durability for damage resistance to equipment, debris-laden and
severe flow conditions▪ Compact profile minimizes need for infill while retaining vegetation
structural support ▪ May not need soil infill due to a more open structure and less thickness
▪ Large-scale 3rd party channel testing conducted with results greater than 15
lbs/sf once vegetated▪ Color woven design, increases tensile retention and UV stability
High Performance (HP-TRM)
Soil/Seed Filled Vegetated Channel Testing at TRI
HPTRM Performance Testing
Soil/Seed Filled Vegetated Channel Testing at TRI
(15 lbs/sf maximum vegetated shear stress)
HPTRM Performance Testing
High-Performance TRMs Properties
“Pyramid” Design
Corrugated netCorrugated “Pyramid”
Roll Size 10 x 90 ft
(100 sy)11.5 x 78 ft
(100 sy)
Vegetated Shear StressASTM D6460
16 psf 15 psf
Vegetated VelocityASTM D6460
25 fps 20-25 fps
Tensile StrengthASTM D6818
3600 x 3800
lbs/ft
3800 x 5000
lbs/ft
UV stabilityASTM D
4355
>80% >80%
(@3000 hr) (@3000 hr)
ThicknessASTM D6525
0.40 in 0.35
(10.2 mm) (8.6 mm)
Mass/Unit AreaASTM D6566
14.7 oz/sy 11.29 oz/sy
(495 g/m2) (380 g/m2)
✓ Sod Overlay to reduce concern of mower interference
✓ Structure of Matrix provides greater frictional surface as sod underlay to keep sod firmly in place until root establishment
✓High compression strength to maintain three dimensionality and maximum root interaction and reinforcement when seed/soil-filled or overlaid with sod
HPTRM Sod Overlay
▪ High Risk projects / Catastrophic events
▪ Geotechnical stability on slopes
▪ Areas with heavy maintenance equipment
▪ High- tensile applications
▪ Examples
▪ Levees
▪ Canals
▪ River banks
▪ Spillways
▪ Steep Slopes
▪ High flow channels
HPTRM Applications
HPTRM InstallationPercussion Driven Earth Anchors
Anchor Installation Demonstration
▪ Start by Placing
Anchor on Tip of Drive Rod
▪ Position Anchor to
Designation Location
▪ Place Gas Driver on
Rod and Set Anchor
to Design Depth
▪ Remove Gas Driver
and Pull Drive Rod
Out
▪ Slide Anchor Cap to
Soil Surface
▪ Tighten Cable and Set Anchor
▪ Clip Extra Cable
HP-TRM Louisiana Levee Protection
HP-TRM Installation
4 month vegetated
➢Unique armoring solution that dramatically elevates the performance against scour. When used with a TRM underlayment, it allows for vegetation use in high scour areas where hard-armor was once the only viable option.
➢ Applications: Shoreline transition zones, channel bottoms, pipe outlets, and more.
Erosion Control Systems
Transition Mats
Channel Scour / Shoreline Protection
Channel Scour Erosion by Wave Action
Tansisition Mat System Applications
Tranisition Mat with TRM for “head-to-tail” drainage protection
◆ Culvert outlets/ pipe outfalls
◆ Curb outfalls/ down chutes from parking lots / steep slope drains
◆ Can utilize earth anchors for added pull-out strength
◆ Transition Mat with TRM or geotextile, can incorporate coir log
toe, and earth anchors
◆ Pond, lake, levee, canal, stream shorelines
◆ Spillway stabilization
Flexible
▪ Easy installation for maximum performance
▪ Earth anchors NOT required – high specific gravity
▪ Will not “float”
Features & Benefits
“Soft” vegetative green solution
▪ Requires no heavy equipment to install
▪ Easier maintenance
▪ Greater safety for vehicles and pedestrians
▪ Increased water filtration compared to rock or concrete
Features & Benefits
➢Shoreline, Channel, Culvert installation guides available
➢ Typically installed with Transition Mat with Stakes, staples, or earth anchors
➢Culvert designs
▪ Width = 3-4 times the pipe diameter
▪ Length = 4-5 times the pipe diameter
Installation
Transition Mat should typically be used in conjunction with a TRM when
▪ Used in high scour, high shear areas
▪ Using seed to vegetate
▪ Most applications
Transition Mat should typically NOT be used with a TRM when
▪ Sod is specified
▪ Moderate areas where an ECB is being used
▪ When the product is submerged with no vegetation (use a geotextile underneath)
Installation
Typical Scour Apron Installation
Transition Mat culvert project, installation through 4 weeks
Installation over seeded TRM / Installation over existing vegetation
Transition Mat placed over seeded TRM
Transition Mat placed over established vegetation
Outfall Application
Transition Mat outfall project, Installed per California Fish and Wildlife
Pipeline Site Drainage
ShoreMax mat channel project,
Center Point Wellhead, Louisiana
Estimated Cost Analysis
Reinforced Vegetated Design
- TRM lining entire channel ($4.00/sy)
- 6 panels Transition Mat ($125 / panel)
- 2 Crew members installing 25 sy/hr each
Hard Armor Design
- 6 in Rock Rip Rap ($35.0/delivered ton)
- 2 Crew members installing 25 sy/hr each
Cost Analysis
Total cost for a Channel Requiring 6 inch D50 Rock Riprap vs Reinforced
Vegetation System with TRM and Transition Mat
Channel is 10 ft x 300 ft
TRM with Transition Mat
Outlet
6 inch Rock
Materials (& Equip) $2188 $7110
Labor $287 $533
Total Installed Cost $2475 $7643
POTENTIAL SAVINGS = $5168 or 68% savings
*Costs will vary depending on location
Wire Fasteners
❖ 6 inch Circle Top Pins
❖ 6 inch V-Top Staples
❖ 6, 8, 10, & 12 inch U-staples
BioStakes, biodegradable plastic T-Staples
❖ 4 inch BioStakes
❖ 6 inch BioStakes
EcoStakes, wooden stakes
❖ 6 inch EcoStakes
❖ 12 inch EcoStakes
❖ 18 & 24 inch EcoStakes (used with Sediment Devices)
Installation Tools
Fastening Devices
EcoStakes
BioStakes
Wire Staples
Rebar Staples
Earth Anchors
Installation Tools
o 300 lb pullout strength
o 1100 lb pullout strength
1. Prepare the seedbed by raking, seeding and applying fertilizer
2. Use trenching procedures to secure terminal edges
3. Keep material in contact with the soil
4. Place staples in appropriate locations using specified staple pattern
5. Secure all product overlaps
6. Ensure seams are shingled to prevent undermining
Installation Guidelines for RECPs
1. Prepare Soil Bed
2. Anchor in leading edge
3. Unroll product
4. Staple using the
correct staple pattern
5. Shingle
overlaps and secure
Typical Installation Guidelines for RECPs
Installation Guidelines for RECPs
Slopes
Installation Guidelines for RECPs
Channels
Shoreline
Installation Guidelines for RECPs
◆ Software designs for the following applications
◆ Channels
◆ Slopes
◆ Vegetation Selection
◆ Spillways
◆ User-Defined Channels
◆ Outlet
◆ Drop Structure
◆ Mattress Channel
Design Software
Assists in selection of:
Temporary Erosion Protection
➢Rolled Erosion Control Products (RECPs)
➢Hydraulic Erosion Control Products (HECPs)
Permanent Erosion Protection
➢ Vegetation
➢Reinforced Vegetation
➢ (TRMs, Transitions mats)
Hard Armor
➢ (Marine Mattresses, rock riprap, concrete)
Design Software Features
Designing with Software Erosion Control Systems
▪ Soil loss calculations based on Revised Universal Soil Loss Equation
(RUSLE)
▪ RUSLE factors rainfall, slope length and grade, soil types, and cover
type.
▪ Failure based on tolerable soil loss limits
▪ Examine temporary blankets, permanent vegetation, & permanent
reinforced vegetation
▪ Analysis for United States, Canada, Australia, Japan, Latin America
and other countries
Slope Module Features
▪ Failure criteria based on permissible shear
▪ Facilitates use of 3 phase design analysis
▪ Accounts for differing vegetation growth habits and densities
▪ Accounts for differing soil types
▪ Analyzes channel bends and composite linings
▪ Analyze product performance with a wide range of vegetation types
Channel Module Features
▪ Analyzes shear force applied to a given channel lining
▪ A single performance value defines each specific channel liner’s performance
▪ Design methods are applicable under a wide range of channel configurations (i.e., trapezoidal, V-shaped)
▪ Determination of increased erosive forces in channel bends
Maximum Permissible Shear Stress Approach
Channel Module Features
“Design of Roadside Channels with Flexible Linings”
▪ Based on permissible shear stress procedures
▪ More concise design methodology than permissible velocity
▪ Procedures for designing all flexible channel liners
▪ Outlines methodology for designing vegetated channels
Federal Highway Administration’s Hydraulic Engineering Circular #15
Channel Module Features
USDA’s Agriculture Handbook 667
▪ Improved definition of vegetative cover (e.g. growth habit and density)
▪ enhanced definition of effective roughness
▪ better definition of cover provided by vegetation
▪ Determination of shear force penetrating vegetation
▪ Calculates shear stress acting on underlying soil
Refining Vegetative Channel Liner Design
Channel Module Features
Erosion Control Technology Council
• https://www.ectc.org/
• Industry Organization comprised of manufacturing professionals
• Product application tutorials and videos
• Product performance categories
• Questions & Answers
QUIZ TIME!
8/12/2019 74
Summary Questions
1. Which product would be a permanent mat:- Straw/excelsior mat- Turf Reinforcement Mat- Straw/coconut mat- Coconut mat
2. Which statement best describes a Turf Reinforcement Mat:- Provides immediate erosion protection- Traps soil particles
- Extends the permissible shear stress limits of vegetation- All of the above
3. Does the USACE recognize green soft armor solution alternatives? Y/N
4. Which design parameter is the best determining factor for addressing erosion protection in
a channel:- Velocity- Gradient- Permissible shear stress- Width
Summary Questions continued
5. Can permanent Turf Reinforcement Mats have biodegradable components? Y/N
6. Which practice would be the most cost effective solution for a 24” pipe outfall:
▪ Rock rip rap
▪ Concrete
▪ Flexible transition mat
7. Is it possible to increase geotechnical stability for shallow-slope failures using TRMs used
in conjunction with percussion driven earth anchors? Y/N
8. Federal Highway Administration uses what hydraulic calculation in their Hydraulic
Engineering Circular #15 guidelines for channels?
▪ Independent laboratory testing
▪ Permissible shear stress
▪ Product material composition
▪ USDA Revised Universal Soil Loss Equation (RUSLE)
Thank You
Questions?