Designing Erosion Control Solutions Presented by Rob Lawson, CPESC, Southeast Regional Manager:
What Is Erosion?
1. SOIL DETACHMENT by wind or water
2. SEDIMENT TRANSPORT downstream or downslope
3. SEDIMENT DEPOSITION in lakes, streams, rivers, fields, streets, etc. Types of Erosion
1. Raindrop Erosion
2. Sheet Erosion
3. Rill and Gully Erosion Rill Erosion
4. Stream and Channel Erosion Types of Erosion
Channel Scour Erosion by Wave Action Problems Associated with Erosion
On-Site Loss of precious topsoil Cost associated with reworking site
Off-Site Sediment Migration from site Choking and filling of lakes, streams and waterways Pollution of waterways Bury fish eggs and aquatic breeding grounds
Potential for extensive litigation costs Regulatory Requirements
NPDES - National Pollution Discharge Elimination System Phase I & II
• Provision of 1990 Clean Water Act
• Enforceable in all states
• Addresses stormwater runoff from construction sites
• Applies to all construction sites of 1 acre or more (may be more strict)
• Requires erosion and sediment control plan
• Potential litigation & fines for non-compliance Where and Why Use RECBs (Rolled Erosion Control Blankets)
Where land disturbing activities take place Where erosive protection is needed until vegetation establishes Use where mulches & blown straw fail How RECBs Work
RECBs provide erosion protection prior to vegetation
Reduce runoff velocity
Improves infiltration
Reduce soil detachment
Absorb raindrop energy
Trap soil particles How RECBs Work
Organic matrix acts as mulch to enhance germination
Improves soil moisture retention
Regulates soil temperature
Supports young plants Product Options
Erosion Control Systems
Rolled Erosion Control Products – Permanent Turf Reinforcement Mats – Temporary Photodegradable Erosion Control Blankets
– Temporary Biodegradable Erosion Control Blankets
Hydraulic Erosion control products - Hydroseeding
Flexible Transition Mats
Sediment Control Fiber Wattles RECPS
Temporary Rolled Erosion Control Blankets (RECB) Photodegradable Biodegradable Classified by Functional Longevity o Ultra-Short Term – 45-60 days o Short Term – 12 months o Extended Term – 24 months o Long Term – 36 months
Permanent Turf Reinforcement Mats (TRM) Traditional Synthetic – up to 14 lbs./sf permissible shear stress values - Composite (Temporary RECB attached to TRM) High Performance (HPTRM) – Woven - High tensile strength - shear stress values up to 16 lbs./sf Guide to RECPs
Straw Excelsior Straw / Coconut Coconut Single Net Double Net Photo accelerated net Natural jute net Synthetic fiber matrix Synthetic woven
Ultra Short-Term Photodegradable
Rapid degrading single net Rapid degrading double net
. Rapid degrading thread . Functional longevity up to 2 months . Ideal for high maintenance areas
Short-Term Photodegradable
Single net
Double net, straw or excelsior
Up to 12 mo. Functionality
Netting & thread are photodegradable Extended-Term Photodegradable
Double net, straw/coconut
Heavyweight UV stabilized top net, lightweight bottom net
Functional longevity up to 24 months Long-Term Photodegradable
Double net, 100 % Coconut
Heavyweight UV stabilized top and bottom net
Functional longevity up to 36 months Biodegradable BioNet Erosion Control Blankets
Benefits of ‘Leno’ Woven BioNet
. Improved integrity over cross-lay . Better matrix retention . Increase tensile strength . Maximum 24 month longevity
. Out perform synthetic nets due to:
. more flexible, contours to soil surface
. better water absorption
. increased cover factor Leno weave
Cross-lay Biodegradable
Ideal for environmentally sensitive areas
Reduced likelihood of wildlife entanglement
Excellent for wetland, bioengineering, and forested site
Increased erosion control capabilities
Provides greater cover than jute and coir nets
Longevity up to 12 months
Biodegradable Applications Typical RECB Slope Recommendations
1:1 2:1 3:1 4:1
> 1:1 1:1 – 2:1 2:1 – 3:1 3:1 – 4:1
Coconut Fiber Straw/Coconut Straw or Excelsior Straw or Excelsior Heavy Net Extended Term Double Net Single Net RECBs Permissible Shear Stress Comparison
Temporary ECB Performance Values
2.5 2 1.5 1 0.5 0
Sod D/S75 C125 PermissibleShearStress (lbs/ft2) S75BN D/S150 SC150 4" rock 6" rock S150BN C125BN SC150BN Blown Straw Permanent Turf Reinforcement Mats (TRMs)
Used wherever shear stress values reach the maximum limits for vegetation alone Enables designer to use “green alternatives” to replace hard armor Concrete rock Slows run-off allowing more sediment to settle out Reduces sediment/retention Pond Maintenance Stops pollution of waterways Porous Mat allows more water to filtrate into the aquafer Reduces liability concerns Reduced Maintenance
Why use TRMs in place of Rock?
Composite Turf Reinforcement Mats
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
Aesthetically pleasing
Substantial cost savings compared to riprap or concrete 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. Composite TRM
TRM Matrix supported by organic protection Performance widely documented Protects soil, seed & root systems from flowing water
Super High Strength Top Net Slopes
3-D Corrugated Center Net Shorelines
Coconut Fiber Matrix Material Channels
Super High Strength Bottom Net Performance
Coconut Fibers Provide 3 Years of Immediate Erosion Control and Mulching
Permissible Shear Stress Values =
Phase 1 Un-Vegetated 3.2 lbs/ft² (153 Pa)
Phase 2: Partially Vegetated 10 lbs/ft² (480 Pa)
Phase 3: Fully Vegetated 12 lbs/ft² (576 Pa)
Comparable to 30 in Rock Rip Rap! Composite TRM Applications Composite Applications Shoreline TRM Shear Stress Comparisons FHWA Specifications
713.18 Permanent Rolled Erosion Control Products Performance Product FHWA Category Requirements
S/C TRM Type 5. A 6 lbs/ft² (288 Pa)
Coconut Type 5. B 8 lbs/ft² (384 Pa) TRM Synthetic Type 5. C 10 lbs/ft² (480 Pa) TRM Economic Benefits
Up to 60% Savings over rock riprap Less expensive to install than soil in-filled TRMs Economic Benefits
Total cost for a Channel Requiring 30 inch D50 Rock Riprap Channel is 3 ft x 16 ft x 1000 ft
C TRM 30 inch Rock
Materials $7,800-9,900 $32,000
Labor $6,400-7,900 $21,300
Total Installed $14,200-17,800 $53,300 Cost ($8-10/yd²) ($30/yd²)
POTENTIAL SAVINGS = $39,100
*Costs will vary depending on location High-Tensile Woven HPTRM
Woven from poly yarns to form high strength corrugated erosion control /vegetation root reinforcement structure
>3,000 lbs/ft tensile strength and 80% min tensile retention @ 3,000 hrs UV Exposure (exceeds EPA HPTRM and USACE prelim HPTRM specs)
High durability for damage resistance to maintenance equipment, water-carried debris and severe flow conditions Performance Features
Soil-filled to allow veg root growth through 3D structure Corrugations form protective “check dams” perpendicular to water flow to prevent soil/seed migration and wash out May require Hydroseeding or RECB temporary blanket over surface for initial erosion protection and mulching action
Performance Features
Sod Overlay to reduce concern of mower interference
Corrugations provide greater frictional surface as sod underlay to keep sod firmly in place until root establishment
Performance Features
High compression strength to maintain three dimensionality and maximum root interaction and reinforcement when seed/soil-filled or overlaid with sod
HPTRM Applications
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 Transition Mat Systems Transition Mat Systems
Used above/below water lines in conjunction with: TRMs Geotextiles Sod
Used in areas subject to scour or wave impact
“Equal-to” replacement for: TRMs (exceeds permissible shear stress of TRMs) Rock riprap Poured concrete or concrete block
Transition Mat Systems
Culvert outlets/ pipe outfalls Curb outfalls/ down chutes from parking lots / steep slope drains Can utilize earth anchors for added pull-out strength Tansistion Mat with TRM or geotextile, can incorporate coir log toe, and earth anchors Pond, lake, levee, canal, stream shorelines Spillway stabilization
Transition Mat 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 Transition Mat Installation
Shoreline, Channel, Culvert installation guides available Typically installed with staples, rebar, or earth anchors Culvert designs Width = 3-4 times the pipe diameter Length = 4-5 times the pipe diameter Pipe Outfall
Transition mat culvert project, Installation through 4 weeks Transition Mat Project
Outfall project, Landfill application Transition Mat Project
Channel project, Center Point Wellhead, Louisiana Cost Analysis
Reinforced Vegetated Design Hard Armor Design - Vmax lining entire channel ($4.00/sy) - 6 in Rock Rip Rap ($35.0/delivered ton) - 6 panels Transition Mat ($125 / panel) - 2 Crew members installing 25 sy/hr each - 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
Vmax with ShoreMax 6 inch Rock Outlet Materials (& Equip) $2188 $7110 Labor $287 $533
Total Installed Cost $2475 $7643
POTENTIAL SAVINGS = $5168 or 68% savings
*Costs will vary depending on location Installation Tools
Wire Fasteners 6 inch Circle Top Pins 6 inch V-Top Staples 6, 8, 10, & 12 inch U-staples BioStakes, biodegradable 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) Rebar Fasteners 12 inch Rebar U-Staple 18 inch Rebar U-Staple Earth Anchors Includes many options regarding materials
Installation Tools
Wire Staples
BioStakes
EcoStakes
Rebar Staples Installation Tools
Earth Anchors
EA400 – 300 lb pullout strength EA680 – 1100 lb pullout strength Installation Guidelines for RECPs
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 1. Prepare Soil Bed
2. Anchor in leading edge
3. Unroll product
4. Staple using the correct staple pattern
5. Shingle overlaps and secure Installation Guidelines for RECPs Installation Guidelines for RECPs
Slopes Installation Guidelines for RECPs
Channels Installation Guidelines for RECPs
Shoreline Sediment Control Devices
Straw Wattles Excelsior Wattles Coir Wattles Compost Socks
To protect areas where erosion control is not applicable
Sediment Control Applications
• Steep Slopes • Forest Fire Rehabilitation • Perimeter Control • Active Construction Sites • Wet Areas
Sediment Wattles
Encapsulated fibers Standard 9 inch,12 inch and 20” diameters Photodegradable diamond netting or biodegradable jute net 3-5 year longevity
Wattle Installation
Step 1: Step 2: Dig Anchor trench and place in Stake into place, every 3-4 ft. trench Sediment Control Spacing on Slopes Why Hydraulic Mulch?
Controls erosion
Eliminates need for “fine grading”
Aids in vegetation establishment
Easy to apply in difficult areas
Increases productivity
Alternative to single and double net erosion blankets
How do hydraulic mulches work?
The mulch mixes with water in a mechanically or jet agitated hydroseeding tank
Add Seed to tank
You may add soil amendments in the tank with seed and mulch
The mulch is hydraulically sprayed on the soil bed
The mixing activates a tackifier in the mulch
The tackifiers bond soil and mulch together
The mulch fibers aid in vegetation establishment by protecting the seed and holding moisture in soil Components of mulch products
Cotton/straw
Straw
Paper (cellulose)
Wood
Wood / Paper Blend
General Mulch Designations
Hydraulic Mulch
Hydraulic Mulch No or limited tackifier Hydraulic Mulch with Tack Up to 5% tackifier incorporated in the mulch, may have additional additives
High Performance Hydraulic Mulches
BFM – Bonded Fiber Matrix Proprietary blend of polymers, tacking agents and/or other additives FRM – Fiber Reinforced Matrix Increased percentage mix of BFM additives, with or without, the addition of synthetic fibers ECTC Classification of Mulches
HP Hydraulic Mulch Extreme General Hydraulic Mulch Recommendations High Performance Hydraulic Mulches
Make sure HP Hydraulic Mulches have Undergone 3rd Party Testing:
. AASHTO-NTPEP
. TRI Environmental
. San Diego State University
. TTI/TX DOT
. State DOT Approval Mulch Field Test University Central Florida ECMDS 5.0 ECMDS 5.0 Features
• Web-based Software • Procedures and Calculations for 8 different project designs • English or Metric Units • English or Spanish • User and Project accounts • Save and print analysis and/or computations • Time Savings Estimators • Document Library ECMDS 5.0 Features
. ECMDS erosion protection design for the following applications . Slopes . Channels . Spillways . Pipe Outfalls . Drop Structures . Vegetation Selection . Free at www.ECMDS.com
ECMDS 5.0 Features
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) ECMDS Slope Module Features
Soil loss calculations based on Revised Universal Soil Loss Equation (RUSLE) Outlined in USDA Agriculture Handbook 703, 1991 Utilized by many federal, state, and local government agencies to predict soil loss Scientifically superior to other methods of predicting soil loss from slopes
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
ECMDS Channel Module Features
Federal Highway Administration’s Hydraulic Engineering Circular #15
“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 ECMDS Channel 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 ECMDS Channel Module Features
Refining Vegetative Channel Liner Design
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 QUESTIONS? Water and Sewer - Details and Specifications Update
Department of Water Management September 8, 2016 1600 MIST LAKE DRIVE DURHAM, NC 27704 P 919.560.4381 Public Works Stormwater Seminar F 919.560.4479
There are number of ways to save water, and they all start with you. Introduction
• Water and Sewer - Details and Specifications are being finalized. • A Letter to Industry will be distributed to notify development community and contractors.
There are number of ways to save water, and they all start with you. Process Revisions
• Water and Sewer – Details, Specifications and Pre- Approved products will now be maintained by Water Management. • All detail and specification variance requests will be reviewed and approved by Water Management. Variance reviews will be coordinated with Public Works Engineering Development Review and Inspections. • All requests for inclusion on Pre-Approved product lists will be reviewed and approved by Water Management. • Send variance and Pre-Approved Product requests to Brian Sessoms at [email protected]
There are number of ways to save water, and they all start with you. Notable Detail and Specification Revisions • Now includes Water and Sewer Pre-Approved Product Lists. • Rigid coupling for in-line material transition for gravity sewer. Only for DIP and PVC. Cannot be utilized with VCP. • Epoxy interior lining for all DIP gravity sewer and force mains. • New BFP details • New Temporary Flushing/Testing Detail
There are number of ways to save water, and they all start with you. Upcoming Process/Design Standard Revisions
• Will Serve Permit. Permit issued by Water Management at the beginning stages of a project. Working with City/County Planning and Public Works to develop this process. • Revisions to the Water and Sewer sections of the Reference Guide for Development. • Lift Station Design Standards. • More to come later…
There are number of ways to save water, and they all start with you. Questions?
There are number of ways to save water, and they all start with you. Public Works Stormwater and GIS Division
GIS Dataset Overview and Acquisition
• https://durhamnc.gov/1303/Custom-Maps-and-Data-Layers
Public Works Stormwater & GIS Division GIS Data Access 101 CITY HALL PLAZA DURHAM, NC 27701 P 919.560.4326 • Various departments in the City and the County maintain many [email protected] layers of GIS digital data. These layers of information are available for public access in several different ways. Online "Public Access" is available for the public to browse selected layers of the GIS database and perform simple queries on the data over the Internet. Standard digital data and hard copy mapping products are available at the Tax Assessor's Office, Planning, Public Works, and the GIS Department.
Durham – Where Great Things Happen Public Works Stormwater and GIS Division
Digital Data Distribution Methods:
Public Works Digital Data Layers are available for download through Stormwater & GIS Division
101 CITY HALL PLAZA the Open Data Site or Durham's FTP (File Transfer DURHAM, NC 27701 P 919.560.4326 Protocols) site. To access the FTP site, customers must
[email protected] obtain permission and a logon code will be provided.
To order, customers can download a Digital Data Request form and Agreement (PDF) and email it to the Technology Solutions/GIS department.
Durham – Where Great Things Happen Public Works Stormwater and GIS Division
GIS Dataset Overview and Acquisition :
Public Works Stormwater & GIS Division Open Data Site (FUTURE)
101 CITY HALL PLAZA DURHAM, NC 27701 P 919.560.4326
[email protected] https://opendurham.nc.gov
Durham – Where Great Things Happen Public Works Stormwater and GIS Division Open Data Site
Public Works Stormwater & GIS Division
101 CITY HALL PLAZA DURHAM, NC 27701 P 919.560.4326
Durham – Where Great Things Happen Digital Data Request form and Agreement (PDF)
https://durhamnc.gov/DocumentCenter/Home/View/3692
City of Durham/County of Durham Geographic Information Systems Digital Data Request Form and Agreement REQUEST BY: DATE OF REQUEST: COMPANY: PHONE: E-MAIL ADDRESS: DATA REQUESTED (Please be as specific as possible): AREA REQUESTED: Public Works DATA FORMAT: [ ] Personal GeoDatabase [ ] ArcView shapefile [ ] DGN [ ] Other ______Stormwater & GIS Division METHOD: [ ] via E-mail [ ] via FTP [ ] CD-ROM [ ] DVD City of Durham and County of Durham shall not be held liable for any errors in the data provided as a result of 101 CITY HALL PLAZA this request. This includes errors of omission, commission, errors concerning the content of the data, and relative DURHAM, NC 27701 and positional accuracy of the data. The data cannot be construed to be a legal document. Primary sources from which the data have been compiled must be consulted for verification of the information contained in this data. P 919.560.4326 Requester agrees to make payment as specified in the City of Durham/County of Durham GIS Data Distribution Policy and to abide by all other provisions of the Policy, as they may be revised from time to time. No use for [email protected] resale or commercial purposes, as defined in North Carolina General Statute Chapter 132-10, is permitted. If this request comes in the course of my employment, the person signing warrants that he or she has authority to bind the employer to abide by the City of Durham/County of Durham GIS Data Access and Distribution Policy and the terms of this Agreement. ______Requester Signature Title Date (Contact Information) City of Durham Technology Solutions Dept / GIS 101 City Hall Plaza Durham, NC 27701 Phone: (919)560-4122 Fax: (919)560-4808 e-mail: [email protected] Office hours: Monday - Friday, 8:00 a.m. - 5:00 p.m.
Durham – Where Great Things Happen Public Works Stormwater and GIS Division
GIS Datasets Managed by PWGIS:
Public Works Stormwater & GIS Division • Street Centerlines / Road Features
101 CITY HALL PLAZA DURHAM, NC 27701 • City Limits / Annexations P 919.560.4326 • [email protected] Impervious Area • Water and Sewer Infrastructure • Stormwater System Infrastructure
Durham – Where Great Things Happen