Fundamentals of Erosion Control

8/9/2019 Fundamentals of Erosion Control

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Fundamentals ofFundamentals of

Erosion ControlErosion ControlUnderstanding and Modification of Soils

Soil PreparationSeed Selection

By Stephen R. Zwilling


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Key factors for successful erosionKey factors for successful erosion

control on projectscontrol on projects

y Planning

y Soil Analysis

y

Plant Selectiony Anticipated Hydraulic Impact and Flow

y Selection of Erosion Control Products

y Selection of Sediment control BMPs

y

Installationy Maintenance


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TerminologyTerminology

y RECP Rolled Erosion Control Products

y SMM Stabilized Mulch Matrix

y BFM Bonded Fiber Matrix

y FRM Reinforced Matrixy BMP Best Management Practice

y RUSLE Revised Universal Soil Loss Equation

y C Factor Cover Factor used in RUSLE

y Percent Effectiveness Inverse of C factorwhich relates to product performance


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Past Seeding PracticesPast Seeding Practiceswill not meet todays standardswill not meet todays standards


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We need to move fromWe need to move fromaa Defensive StrategyDefensive Strategy Sediment ControlSediment Control(trapping soil particles(trapping soil particlesafter dislodgment)after dislodgment)

To anTo an OffensiveOffensiveStrategyStrategy UpgradedUpgradederosion controlerosion control

practicespractices


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NO3PO3NO3

y Nutrients retained and available to plantsy

More efficient utilization of nutrientsy Reduced runoff into water bodiesy Response to NPDES Regulations

Source: Arise Research & Discovery, Inc.

Balanced and Fertile Soils Retain

Nutrients

"Bio-Mass"Created

Roots

Rainfall Runoff Lake or Stream

Established Vegetation

NO3

PO4NO3

NO3

PO4

NO3PO4

NO3

PO4

FertilizersApplied


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How to pick the RightHow to pick the Right

Vegetation solution?Vegetation solution?

What should I plant?What is my budget?How can it be stabilized?What am I trying to achieve on this site?

Picking the right erosionPicking the right erosion

control product is critical!control product is critical!


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Understanding your soil and your plantUnderstanding your soil and your plantmaterialmaterial questions to answerquestions to answer

y What kind soil are you working with?y How well does it drain or retain water?

y Is a balanced environment PH organics?y

What vegetation works well in this soil?y What is the range of slope gradients?y Were are the areas of concentrated water flow?

y What am I going to do with the water?y What are the local sediment control regulations?y What is the expected precipitation?y What are my soil management and vegetation

objectives / budget?


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SoilsSoilsUnderstanding and modification of soils


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PedogenicPedogenic (soil(soil--formingforming))ProcessesProcesses

y Material Strength

y Infiltration Capacity

y Plant Productivity

Can be altered by the erosion process. Soilsability to resist stresses can be altered by

y Weathering and climate

y Pedogenic processes

y Decomposition of organic matter


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Accelerated ErosionAccelerated Erosion

y Removes the upper layer (A-horizon) of the soilexposing the (B-horizon) which generally possessdifferent strength properties.

Accelerated erosion can impact the soils ability toresist stresses from

y Rainfall impact

y Surface runoff

y Wind erosion


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Infiltration CapacityInfiltration Capacity

y The ability of the soil to absorb water isgenerally greater in the (A-horizon) than the

(B-horizon)

y Precipitation is then divided into

y Soil Moisturey Surface Runoff

y Groundwater Runoff


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Soil Properties that ImpactSoil Properties that Impact

VegetationVegetationy Slow draining compacted soils might only support

hydrophytic (wetland) plants

y Fast draining sandy soils may only support

xerophytic (desert land) plantsy Soil particle-size can dictate plant selection

y The finer the particle size, the more waterholding capacity because of available surface

areay Generally soils consisting of 70% sand-size

particles are considered droughty


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Agronomic ConsiderationsAgronomic Considerations

y Vegetation is critical to long-termerosion control

y Enhance germination by providing the

plant what it needs during first stagesof growth

y Assure long-term plant survivability

y Establishment of healthier vegetationand less nutrient run-off


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Soil Tests are Critical:Soil Tests are Critical: They MeasureThey Measure

pHpH

Organic MatterOrganic Matter (must be higher than 2%)(must be higher than 2%)

Electrical ConductivityElectrical Conductivity Total Dissolved SaltsTotal Dissolved Salts

Sodium Absorption RatioSodium Absorption Ratio

% Organic Acids% Organic Acids

CationCation Exchange Capacity (CEC)Exchange Capacity (CEC) Nitrogen, Phosphate & Potassium (N, P, and K)Nitrogen, Phosphate & Potassium (N, P, and K)


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What is pH?What is pH?

y pH is shorthand for its mathematicalapproximation:

y a small p is used in place of writing log10 and the H represents [H+], theconcentration of hydrogen ions present in thesoil solution

y pH measures the acidity or alkalinity of asolution

y pH of 7 is neutraly Each unit is 10 times that of the previous or

next unit


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Electrical Conductivity (EC)Electrical Conductivity (EC)

y Measure of the overall salt content in a soily Add distilled water to the soil and measure its

ability to conduct electricityy A test value above .5 can negatively impact

establishment, higher the number the worse it is,7 is toxic plants

y Sea water measures 55


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Total Dissolved Salts (TDS)Total Dissolved Salts (TDS)

y Directly related to EC but a different scaley TDS measured by parts per million

y EC of 1.0 x 640 ppm = Total Dissolved Salts640 ppm

y TDS is sometimes stated as Total SolubleSalts (TSS), also Soluble Salts (SS)


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SA

R SodiumAb

sorption RatioSA

R SodiumAb

sorption Ratioy Represents the proportion of sodium out of

the total salts in the soil

y Important because sodium can be toxic to plants

y EC of 1.0, contains Ca and Mg soil is fine

y EC is 1.0 and it is derived from Sodium it would

be toxic to plants SAR measures this

y SAR above 7.0 is toxic to most plants


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Sodium as % CEC BaseSodium as % CEC Base

SaturationSaturation

y Sodium as a % CEC measures the negativeimpact on soil physical properties

y High sodium levels can cause the soil becomenearly impervious to water

y Causes severe compaction issues

y Values exceeding 15 - 20% can be toxic to

plants


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Organic Matter (OM)Organic Matter (OM)

y Organic matter in soil is the result of the decayprocess

y OM reduces compaction in Clay soils

y OM improves the structure of Sand and Silt,holding nutrients and moisture

y Low Organic matter means low CEC and adeficiency in Nitrogen for long term plant heath

y Optimum level is 3 to 5% of the dry weight of

soil


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Organic Acids (OA)Organic Acids (OA)

y Organic Acids is the measurement of the livingbiological composition of the soil

y The value should be 3.0, compare to OM%, ifOM is low and OA is low, the soil is a mineralbased lifeless soil

y OM% is high and OA is low, it still indicates a

lifeless soil that needs a boost in the microbepopulation to break down the organic matter.


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EC1 TDS2 ppm SAR 3

CEC%

Sodium4 OM5 OA6

Plant

Sensitivity

< .75 < 480 < 3 < 4% > 2% > 2.5% Moderate.75 1.5 480 960 3 4 4 6% 1.5 2 1.7 2.5% Problematic

1.6 3.0 1024 1920 4 5 6 7% .75 1.4 1 1.6 Severe

> 3.1 > 1984 5 - 6 7 9% < .75 < 1 Critical

Optimal

EC1 TDS2 ppm SAR 3

CEC%

Sodium4 OM5 OA6

< .4 < 256 < 2 2.5% 3 5% > 3 Ideal

Toxic

EC1 TDS2 ppm SAR 3CEC%Sodium4 OM5 OA6

> 7 > 4480 > 7 15 20%7 N/A N/A Toxic

1Electrical Conductivity 2Total Dissolved Salts 3Sodium Absorption Ratio 4Sodium as percent(%) Base Saturation Cation Exchange Capacity CEC 5Organic Matter 6Organic Acids 7Varies by

Plant Material


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Soil NeutralizersSoil Neutralizers

y pH is second only to moisture availability inimmediate impact on vegetation establishment

y

Optimal pH values allow nutrients to be morereadily available to plants

y Important to quickly modify soil pH prior to seedgermination


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pH Affects Nutrient UptakepH Affects Nutrient Uptake


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Options to Change pHOptions to Change pH

y Add standard lime to raise pHx Generally takes several weeks to become active

y Add quick release lime products for

immediate resultsx Liquid or powdered lime products

y Add sulfur to lower pH(2-4 weeks prior to planting)

y Add quick acting soil buffering productsx Products like Aqua Fix


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Acidification opportunity everywhere but yellow

General USA pH levelsGeneral USA pH levels


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Organics need to be above 2%Organics need to be above 2%

y Some options for modifying organics

y Amending/blending top soil

y Addition of gypsum

y Addition of Pours ceramics to soils

y Soil penetrators to improve infiltration

y Soil inoculants such as Endo MycorrihizaeEndo Mycorrihizaeto stimulate hyphae growth


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Hauling in soil isHauling in soil is

an fast option toan fast option toimprove organicsimprove organicsbut generallybut generallyexpensiveexpensive

Organic orOrganic or

chemical additiveschemical additivesare an option toare an option tomodify soilmodify soil


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Clay Compaction

Soils with high clay content andsalt overload, causes the clayplatelets to move even closerto each other, forming a 3-Dstructure.

Humic Acid encourages waterpenetration, as it penetrates

the clay particle, it segregatessalts and removes them fromthe surface of the platelet, thisaction restores the neg chargeto the clay platelet, forming 3-D structure.


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EndoEndo MycorrhizaeMycorrhizae option for soiloption for soil

modificationmodification Enhances the absorptive rate of the root hair by 10 fold

Hyphae can enter, micro pores in the soil that the root hair is too

thick to extract water or nutrients

Produces an antibiotic reducing disease pressure for the plant

Through a symbiotic relationship with the plant, fungi sources

food, carbohydrates, vitamins and amino acids, in exchange,

fungi supplies plant water, macro & micro nutrients

Erosion benefit, life cycle is 17 to 30 days,secrete glue like substance, and at death

they decayand feed the soil bacteria

population, further aggregate the soil.


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Case StudySumter County LandfillSouth Carolina

Application summer 2008pH very low - 4.5Organics very low - 0.9 %

Soil Modifiers AppliedGrowth after 6 weeks


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Modifying Soils are a BMPs


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Establishing VegetationEstablishing VegetationFor soil stabilization


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SeedingSeeding

y Quick revegetation ofdisturbed sites

y Requires selection of

appropriate seed mix

y Soil must have nutritionalvalue or be amended

y Site specific stabilizationmaterials are needed tokeep seed in place


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Seed Used for Erosion ControlSeed Used for Erosion Control

y Cool Season Tall Fescue- cool season perennial Ryegrass- cool season annual

y Warm Season Bermuda grass- warm season perennial Bahia grass- warm season perennial

Brown top Millet- warm season annualy Slopes

Weeping Love grass- warm season perennial Serecia Lespedeza- warm season perennial

x hulledx unhulled

Cloversx White Clover- cool season perennialx Crimson Clover- annual re-seeding clover


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FescueFescue


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Annual RyegrassAnnual Ryegrass


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BermudagrassBermudagrass


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BahiagrassBahiagrass


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BrowntopBrowntop MilletMillet


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Sericea LespedezaSericea Lespedeza


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Weeping LovegrassWeeping Lovegrass


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CloversClovers


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Cool Season GrassesCool Season Grasses

Variety LB/Acre Lb/1000 sq ft

General Planting

Dates

Typical

Germination Time

MinimumGermination

Temperature (Soiltemp @ 4in

Degrees F)

Kentucky 31 300-350 6.89-8.03 Aug. 15 - May 1 21 days 45

90/10K31/Orchardgrass 300-350 6.89-8.03 Aug. 15 - May 1 21 days 45

Turf type tall fescueBlends 300-350 6.89-8.03 Aug. 15 - May 1 21 days 45

Chewing Fescue 200-250 4.59-5.74 Aug. 15 - May 1 21 days 45

Hard Fescue 200-250 4.59-5.74 Aug. 15 - May 1 21 days 45

WinterTemporaryMix 150 3.44 Nov. 15 - Mar 1 21 days 40

Annual Ryegrass 150 3.44 Sept. 1 - May 1 21 days 44


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Warm Season GrassesWarm Season Grasses


Hulled Bermudagrass 50-80 1.14-1.83 Apr 15 - Sept 1 30 days 65

unhulledBermudagrass 50-80 1.14-1.83 Sept. 1 - April 15 30 days 65

Hydro Bermuda Blend 80 1.83 Apr 15 - Sept 1 30 days 65

Bermuda Triangle 80-120 1.83-2.75 Apr 15 - Sept 1 30 days 65

Princess 77 40-80 1.00-2.00 May 15 - Aug 15 30 days 65

Browntop Millet 20 0.5 May 1 - Sept 1 21 days 65

Pensacola Bahiagrass 80 1.84 Apr 15 - Sept 1 30 days 65

Weeping Lovegrass 10-20 lbs .25-.50 year around 30 days 65

Centipede 10-20 lbs .25-.51 Apr 1 - Aug 15 60 days 65

Hulled SereciaLespedeza 25-35 .58-.80 April 15 - August 15 60 days 65

unhulled SereciaLespedeza 25-35 .58-.80 August 15 - April 15 60 days 65

Kobe Lespedeza 25-35 .58-.80 April 15 - August 15 60 days 65

Interstate SereciaLespedeza 25-35 .58-.80 April 15 - August 15 60 days 65


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Clover and Wildflower BlendsClover and Wildflower Blends

Clovers


While Clover 15 0.34 Sept 1 - Mar 15 30 days 50

Crimson Clover 15 0.34 Sept 1 - Mar 15 30 days 50

Wildflowers/Native Blends


CGIG Southeastern Mix 20 0.5

winter or early

spring is best No Fertilizer

Retention Pond Mix 20-25 .5-.58 year around


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Stabilizing SoilsStabilizing SoilsWith Erosion Control


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Key Objectives in Soil Management forKey Objectives in Soil Management forSite DevelopmentSite Development

Planning and project phasing

Focus on erosion control measures / backfilling withsediment management BMPs

Understanding hydraulic flows - designing cost effectiveconveyances stabilizing shorelines and channel flows

Systems to minimize turbidity in transference criticaldischarge points

Stabilizing soils and effective vegetation establishmentunderstanding soil profile / plant selection


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Types ofTypes of ErosionErosiony Splash Raindrop impact,

dispersal and mobilization ofsoil particles

y Sheet Saturated soils, soilparticles entrained in run-off

water, uniform erosion

y Rill Increased topographicrelief, Higher run-offvelocities, soil incision

y Gully Concentrated flow,head cutting, down cutting


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What Influences ErosionWhat Influences Erosion

y Rainfall Intensity and Durationy Soil erodibility factory LS Factor (Flow path / Length & Slope)

Approximately 70%of all storm drainslead directly into openwaterways without

any treatment.


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Total

Kinetic Energy of Rainfall

Total

Kinetic Energy of Rainfall

y One square mile areay 30 annual rainfall

y Equivalent to 10,000 tons ofTNT

Ref: (Meyer and Renard, 1991)


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Revised Universal Soil Loss Equation

A = R x K x LS x C x PWhere:A = computed soil loss per unit area per unittime for a given storm period and intensity

R= rainfall factor

K = soil erodibility factor

L = slope length factor

S = steepness factorC = vegetation or cover factor

P= erosion control practice factor


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C FACTORIS CRITICAL FOR EROSIONC FACTORIS CRITICAL FOR EROSIONMANAGEMENTMANAGEMENT

The lower the C Factor or (Cover Factor) an erosioncontrol medium has better control of soil loss.

High C Factor Low C Factor


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CONCRETE

BLOCK SYSTEMS

CONCRETE

PAVING

ROCKRIPRAP

DegradableBlankets

orSpray onBlankets

STRAW & HYDRAULICMULCHESDO NOTHING

Limits of Natural Vegetation

Velocity- 1.5 - 1.8 m/sec

(5 - 6 ft/sec)Shear stress - 100 N/m2

(2.1lb/ft2)

Limits of NaturalVegetation

Techniques forcontrolling

erosion

Highervelocities/shearstress, Steeperslopes


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Straw MulchStraw MulchAdvantages

Low cost seedingpractice

Fast way ofdistributing seedand mulching

Disadvantages

Poor erosion control qualities

Weed seed contamination

Messy and can blow away


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Erosion BlanketsErosion Blankets

Easy to transport

Ideal for areas with critical

slopesWide range of choices strength, longevity andmaterials

Effective soil stabilization BMP

Requires a fine graded soil

Requires staples

Needs good soil contact


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Proper installation, staple patters andProper installation, staple patters andgrading are critical for successgrading are critical for success


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HydroseedingHydroseeding

Can be customized siteCan be customized sitespecificspecific

Economical way to grow grassEconomical way to grow grass

Provides a wide range ofProvides a wide range ofperformance platformsperformance platforms

Minimal laborMinimal labor very efficientvery efficient


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Mix into hydroMix into hydro--seeder, add seed and fertilizerseeder, add seed and fertilizerthen shoot from hose or cannonthen shoot from hose or cannon


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Mulch Rates Makes a Big Difference inMulch Rates Makes a Big Difference inResultsResults

Test Plot 1 After 18 DaysTest Plot 1 After 18 Days(1,500 lbs. mulch)(1,500 lbs. mulch)




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Types of Fiber MulchTypes of Fiber Mulch

Seeding Mulches

y Cellulose

y Cellulose / tack

y Blendy Blend with tack

y Palletized fiber

y Wood Fiber

y

Wood with Tack

Erosion ControlMulches

y Stabilized Fiber Matrix

(SMM)y Bonded Fiber Matrix

(BFM)

y Fiber Reinforced Matrix(FRM)


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Stabilized Mulch Matrix (SMM)Stabilized Mulch Matrix (SMM)

y Pre-blended forconsistent performance

y Non-toxic, safe &biodegradable

y 3 month longevity (oneseason)

y Flat pads and moderateslopes (


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Bonded Fiber MatrixBonded Fiber Matrix

y

Application rate can be customized toaccommodate steep, rough or irregularly shapedslopes

y Cost effective versus sod or erosion controlblankets

y Saves time and labory

Approved by numerous DOTs and agenciesy Not designed for areas of

concentrated water flowy Functional Longevity -

6 months


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Fiber Reinforced Matrix (FRM)Fiber Reinforced Matrix (FRM)


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Slope Protection Guidelines by Product Category


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Applying FRMApplying FRM -- BFMBFM -- SMMSMM

y Use a fan-type nozzle (50-degree tip) whenever possible

for best soil surface coverage.y Apply FRM from opposing directions to soil surface reducing

the shadow effect and assuring a minimum of 95% soilsurface coverage.

Proper Application Improper Application

Proper (FRM) ApplicationProper (FRM) Application


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Proper (FRM) ApplicationProper (FRM) Application


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Options for moderate to high flowOptions for moderate to high flowareas on slopes or conveyanceareas on slopes or conveyance

y Rip rap

y Articulated block systems

y Concrete lined channels

y Retaining walls

y Turf Reinforcement Mats


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CONCRETE

BLOCK SYSTEMS

CONCRETE

PAVING

ROCKRIPRAP

DegradableBlankets

orSpray onBlankets

STRAW & HYDRAULICMULCHESDO NOTHING

Limits of Natural Vegetation

Velocity- 1.5 - 1.8 m/sec

(5 - 6 ft/sec)Shear stress - 100 N/m2

(2.1lb/ft2)

Limits of NaturalVegetation

Techniques for

controlling

erosion

Highervelocities/shearstress, Steeperslopes

Remember thisslide?


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riprapriprap

Riprap

Traditional ApplicationTraditional Application


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alternative to hard armors (tires)alternative to hard armors (tires)

and other less traditional...and other less traditional...


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cars (interlocking engine block technology)cars (interlocking engine block technology)

...forms of...forms ofarmorarmor

NASCAR Riprap


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TRMsare

classifiedasa softengineering practice, in

contrastto concreteandriprap, whichthey may

replace in certainerosion controlsituations.


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In addition to reducing

flow velocities, the use of natural vegetation

provides particulate contamination removal

through sedimentation a nd soil infiltration, and

improves the aesthetics ofa site.


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SOIL CONTACT: Establishing intimate contact with the final

soil grade is essential for any successful TRM installation

ANCHOR TRENCHES: Protecting the integrity of the TRM

with proper termination, longitudinal and check slot anchortrenches is the final essential issue in successful TRM

installation

ANCHORS: Proper anchor selection, frequency andpattern is another essential aspect of successful TRM

installation

Keys to TRM InstallationKeys to TRM Installation


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TRM InstallationTRM Installation


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Installation

Required to prevent flow leaving reinforced area

from taking soil with it.

Initial anchorInitial anchor

trench detailtrench detail


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Installation

Longitudinal anchor

trench detail

Required to prevent flow coming in along sides of channel,

or overtopping protected area, from undercutting mat.


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Installation

Help to anchor mat and provide protection from problem

spots running the length of the mat installation.

Intermittent

check slot

detail


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finished check slotfinished check slotpicturepicture

Finished check slot installation

results in a number of segmentedinstallations

A hA h


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AnchorsAnchors

TRMs at a minimum use 8x

1x 8 8 Gauge U shaped

Staples, 12 welded wire pins

ate recommended in many

applications

ECBs generally use 6x 1x 6

11 Gauge U shaped Staples

6

12

18

For hard or rocky soils, heavy

duty 6 nails with washers can

be used to anchor TRMs

18 geotextile pins with washers may be usedFor sandy soils 12 or

1:1


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Anchor patterns are determined by steepness of slopes and channel beds

Anchors:Frequency and

Patterns

Installation

1 Anchor / yd2

3

3

6

1 Anchor / yd2

3:1

3

3

6

11/2 Anchor / yd2

2:1

3

24

4

2 Anchor / yd2

3

1.5

3

3

1.5

2 1/2 Anchor / yd2


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The goal is fully vegetated turfThe goal is fully vegetated turfreinforcementreinforcement


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FRM

3DTRM/FRM

April 2005 August 2005

Cost effective system for channel stabilizationCost effective system for channel stabilizationwith a TRMwith a TRM


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Reduced Site Disturbance


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Reduced Site Disturbance

Seven TrucksRequired to Removethe Over-Excavatedmaterial, and...

By reducing the undercut excavation, one roll ofTRM can

eliminate as many as

ive Trucks Requiredto Bring in the

Ri ra .


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General Guidelines for Product SelectionGeneral Guidelines for Product Selection

General seeding for areas 5:1 or less

Seed and Straw / Hydroseeding / broadcast seeding

Slopes 5:1 to 3:1Seed and Straw with tack / Hydroseeding with tack

Slopes 3:1 to 2:1

Erosion Control Blankets / Bonded Fiber MatrixTRM or FGM

Slopes 2:1 to 1:1Erosion Control Blankets / TRM or FRM

Slopes 1:1 or greaterTRM /FRM or structural support


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ConclusionConclusion

Critical factors for SuccessCritical factors for Success

Understanding soil compositionTesting soils and modifying problemsPicking the right vegetation for site conditionsReducing erosion by installing effective erosionand sediment control products

Managing areas of concentrated flowMaintaining good environmental stewardship


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For more information on thisFor more information on this

presentation you can contact me atpresentation you can contact me at

Stephen ZwillingMarket Development ManagerProfile Products LLC(704) 840-6770

[email protected]@profileproducts.com

Documents

Fundamentals of Erosion Control