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STABILIZINGEFFECTSOFTREEROOTS

Anchoring: HighSoil Cohesion: High

Anchoring: HighSoil Cohesion: High

Moderately Deep Soils Shallow Soils

Individual trees are stable without dependence on adjacent trees.

Potential failure plane isreinforced by roots.

DependentonSpecies,Soils,Geology,Hydrology&Slope

A B

A B

STABILIZINGEFFECTSOFTREEROOTS

Moderate if not compromised. Tends to become rapidly unstable when disturbed.

Anchoring: MinorSoil Cohesion: High

Shallow Soils Deep Soils

Unstable soils are deeper than rooting level.

Anchoring: MinorSoil Cohesion: Moderate

DependentonSpecies,Soils,Geology,Hydrology&Slope

C D

C D

FIDALGOISLAND

EXAMPLEOFC‐‐ anchoring:Minor soilcohesion:High

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EFFECTSOFSHEARSTRESSONTREEROOTSSite Hydrology Is An Important Consideration

Courtesy of Dr. Roy Sidle

SOILSHEARSTRENGTH

TREEROOTS

INCREASESHEAR

RESISTANCE

DENSESPACINGOFWEAK‐ROOTEDTREESMAYINCREASESHEERSTRESS&CONTRIBUTE

TOSHALLOWLANDSLIDEACTIVITY

REDALDER

backtoourscheduledbroadcast

Illustrationsadaptedfrom:

VegetationInfluencesonDebrisSlideOccurrencesonSteepSlopesinJapan,Y.TsukamotaandO.Kasakobe.1984

“Trees,Soils,Geology,andSlopeStability”www.greenbeltconsulting.com

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BIO‐STRUCTURALENGINEERINGFOREROSIONCONTROL&SLOPESTABILIZATION

ElliottMenasheGreenbeltConsulting

INTRODUCTIONTOLANDSCAPESONTHEEDGE

NOV.15‐16,2016

Finney,K.1993.HistoryofSoilBioengineering.Mastersthesis,Univ.ofOregon.

ChinaEarly1900’s.Bundlinglivestemsforuseinriverbank

EuropeEarly1900’s.Cuttingandcollectionoflivestems

PEOPLEHAVEBEENUSINGNATIVEVEGETATIONINENGINEERINGPROJECTS

FORALONGTIME

CHINESEHAVEUSEDPLANTSFOR

EROSIONCONTROLFOR2,000YEARS

wovenwillow‘mattress’&brushlayeringMissouriRiver,circa1925‐30

USARMYCORPSOFENGINEERS

WILLOWMATTRESS

BRUSHLAYERING

afterWWII,withincreasedavailabilityofheavyequipment,civil&geotechnicalengineers

begandependingmostlyuponinertmaterialssuchastimber,steel&concreteforerosioncontroltheuseofvegetation‘felloutoffashion’

willow(Salix)specieswerethemostcommonplantsvegetativetechniqueswereusedextensively

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BioengineeringforLandReclamation&Conservation

PublishedinGermanbyHugoMSchiechtl

In1973

TranslatedfromtheoriginalGerman

andpublishedbytheUniversityofAlberta

Pressin1980

THISPUBLICATIONRENEWEDINTERESTINTHEUSEOFVEGETATIONIN

EROSIONCONTROLENGINEERING

DonaldH.GrayAndrewT.Leiser

BiotechnicalSlopeProtectionandErosionControl,1982

BiotechnicalandSoilBioengineeringSlopeStabilization,1996

DonaldH.GrayRobbinB.Sotir

Lewis,L.2000.USDAForestService.Technology&DevelopmentProgramPUB#SDTDC‐00771801

SoilBioengineeringAnAlternativeforRoadsideManagement:APracticalGuide

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soil‐bioengineering&biotechnicalmeasureshavebeenemployedinstream‐bank

restorationfordecades

Source:USDANaturalResourceConservationServiceBRUSHMAT WATTLE

• livestakes• fascines(wattles)

• livecribwalls

• livefencing• livesiltfences• livepoledrains• livecheckdams• brushmattresses

• logs&deadwood

SOILBIO‐ENGINEERING

livefencing

employsonly vegetationorothernaturalmaterialstocontrolwater,reinforcesoils&stabilizeslopes

wattles

brushmattress

livestakes

SoilBioengineeringtechniquesusedprimarilyforstreambankerosion&sedimentcontrol

NUMEROUSTECHNIQUESHAVEBEENDEVELOPED

BIOTECHNICALENGINEERING

• vegetatedgeotextile

• greengabions

• vegetatedriprap

• vegetatedcribwall

employsbothvegetative&syntheticmaterials

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BOTHSOILBIOENGINEERING&BIOTECHNICALPRACTICES HAVELIMITED

USEFULNESSFORLANDSCAPINGAPPLICATIONS

theybothdependprimarilyupontheuseofvegetativecuttings

LIVECUTTINGS:• needadequatesoilmoisture

• agoodlocalsourceofplantmaterials• havealimitedinstallationperiod•mustbedormantwheninstalled•havelimitedornamentalvalue

BIO‐STRUCTURALEROSIONCONTROL&SLOPESTABILIZATIONAPPROACH

the intentional useof desirablenativevegetationspecies asan integralcomponent inslopeengineering

applications&projects

Vegetation +conventionalengineering=aneffectivelong‐term,integratedsolution

WHYAREBIO‐STRUCTURALMETHODSDESIRABLEINENGINEERING?

• plantsprovideadditional:waterrunoffmanagementsedimentcontrolerosioncontrolshallowlandslideresistance

• providemanyotherecosystemservices

• regulatoryincentivesESAstormwater“no net loss” constraints

NORTHKINGCOPROJECT20152nd YEAR

geo‐gridover

geotextilesoilnails

coirlogs

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NATIVEPLANTSAREEFFECTIVEENGINEERINGMATERIALS

fibrousroots

rootsprovidesignificanthydrologic,structural&mechanicalbenefits

coarseroots

TREESALSOADAPTTOALTEREDCONDITIONS

originalgroundlevel

engineeredstructuresdon’t

BENEFITSOFASUCCESSFULBIO‐STRUCTURALPROJECT

GEOTECHNICALENGINEERING• structuralstabilization• hydrologiccontrols• surfaceerosioncontrols• sedimentcontrolsECOLOGICALRESTORATION• invasiveplantcontrol• desirablevegetationestablishment

• naturalizationofthesite• long‐termecologicrestoration

• distant‐viewaestheticbenefits

CHRISTINETASSEFFPHOTO

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BIO‐SRUCTURALENGINEERINGALLOWSUSEOFABROADRANGEOFPLANTSPECIES

groundcoversshrubstrees

WANATIVEPLANTSOCIETY

BIO‐SRUCTURALENGINEERINGALLOWSABROADERRANGEOFPLANTINGSTOCKCHOICES

ANDALONGERPLANTINGPERIOD

USDAFORESTSERVICENURSERY

tubesplug

GEOTEXTILESPROVIDEIMMEDIATEINVASIVEPLANT,WATER&EROSIONCONTROL

polypropylene‐reinforcedcoirerosion‐controlblanket(ECB)

nonwovenfilterfabrics

naturalfiberwater&erosion

control

syntheticfiberinvasiveplant

control

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GEO‐CELLSYSTEMS

SOILNAILSWITHASTRUCTURALFACINGARECONDUSIVETOPLANTING

geogridfacingreinforcement&stabilizationofunstableslopeswithsoilnails

SOILNAILSMIMICSHEARSTRENGTHREINFORCEMENTOFSOILBYTREEROOTS

soilnailinstallation

RESISTANTZONE

ACTIVEZONE

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CRIBWALLS

NOTALLMATERIALS&TECHNIQUESAREEFFECTIVEORUSEDCORRECTLY

poorstormwatercontrol

shallow‐rootedgrasscover

sediment

StrawErosionControlBlanket

extremelyshort‐term&temporary

JUTE(BURLAP)OPEN‐MESHNETTING

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HYDRO‐SEEDING

inexpensive

oftenineffective

doesnotcontrolrunoff

allowsestablishmentofundesirablespecies

GRASSALSODISCOURAGESESTABLISHMENTOFMOREDESIRABLEVEGETATION&CANINTRODUCENOXIOUSWEEDSONTOASITE

useofgrassshouldbediscouragedin‘vegetated’projects

doesn’tpreventnoxiousweedestablishmentHYDRO‐MULCHING

atbestonlyatemporaryerosioncontrolsolution

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theyoftenincludeinvasiveplants&noxiousweeds

avoiduseofgrass&“wildflower”seedinhydro‐mulchmixes

SOMESOLUTIONSAREJUSTABADIDEA

LungFuShanCountryPark,HongKong,China

SHOTCRETEorGUNNITE

SOMEENGINEERINGSTRUCTURES&PROJECTSARENOTCONDUSIVETOAVEGETATIONCOMPONENT

ROCK‐FILLEDGABIONS

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SLOPESTABILIZATIONPROJECTSITESAREOFTENHARSHENVIRONMENTS

USHIGHWAY1012001USGS

STRUCTURALFILL&SITEPREPARATIONrequiretheabsenceofallorganicmaterial

imagecourtesyofR.B.JergensContractors.

notaplant‐friendlyenvironment

REVEGETATIONREQUIRESFERTILESOILS

Texture Structure Fertility Organicmattercontent

BulkDensity SoilpH Nutrients(asperASLALANDSCAPESOILSSPECIFICATIONS)

structuralfillmaterialswillnot growplants

STOCKPILE&USENATIVESOILSSTRIPPEDFROMSITE

soilcharacteristicstoconsiderforplantgrowth:

coverstockpilestominimizeerosion&infestationbyinvasiveplants

locatestockpilesawayfrompreservationareas

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mycorrhizalinoculantsimprovegrowth

inoculated notinoculated

DIPPLANTSININOCULATESOLUTION

promotesbetterwaterandmineralnutrientuptake

SITEASSESSMENTFACTORS• ErosionalProcesses

• PhysicalSiteCharacteristicstopographygeomorphologyprecipitationhydrologysoilmoisture&fertilityelevationslope&aspectstratigraphyfluvialprocessesshoreprocesses

• ExistingVegetation• ClimaticConditions• Socio‐politicalConsiderations• Logistical&EconomicConstraints

WHATARETHECRUCIALPROJECTSITECHARACTERISTICS?

FAILEDCUT‐BANKSTABILIZATION

REFERENCESITES&INDICATORSPECIEShelpdefinecharacteristicsofthesiteenvironment

INVASIVEPLANTS

SKUNKCABBAGE MADRONEHIMALAYANBLACKBERRY

WINDY

OLD‐GROWTHSTUMP

KEEPINMINDTHATTHEPROJECTSITEMAYNOLONGERRESEMBLEREFERENCESITES

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IDENTIFY&PRESERVEVALUABLEEXISTINGVEGETATION

PROTECTESTABLISHEDNATIVEPLANTSTHROUGHOUTPROJECTSITE

COIRGEOCELLINSTALLATION,LAKETAHOE,CA

INVASIVEPLANTCONTROL

DONOTUSEPLASTICSHEETING!

non‐wovenpermeablegeotextile

HIMALAYABLACKBERRY

CRUCIALTOAPROJECT’SSUCCESS

LIVEPOLEDRAINS

vegetatedinterceptiontrenches

SITEHYDROLOGYISOFTENACRUCIALCONSIDERATION

MAYHELPSOLVEPERCHEDWATER

PROBLEMS

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ADAPTEDFROM: “LIVINGONTHECOAST”,USArmyCorpsofEngineers,2003

SAND

SAND/GRAVEL

SILT/CLAY

TILL

CLAY

PUGETSOUNDBASIN

HYPOTHETICALPUGETSOUNDBLUFF

greatly simplified!

TILL

seeps topsoil

PLANTSELECTIONCONSIDERATIONS• nativetoarea• appropriatetosite(sun‐shade,soils,salt‐tolerance,etc)

• favorablespread&reproductivecapability

• superiorerosion‐controlvalue

• superiorrootstrength(rootswithhightensilestrength)

• droughttolerant(onceestablished)

• commerciallyavailableRED‐FLOWERINGCURRANT

PLANTING&INSTALLATIONCONSIDERATIONS

• Speciesselection• Plantstocktypes• Locallysourced?• Spacing/Density• Soilimprovementfertilitymycorrhizae

• Irrigation• Animal&abioticdamageprotection

CHRISMADDENCARTOON

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THEPROJECTSITEMUSTBESTABLEFORATLEAST 15YEARS

OFF‐SITEINFLUENCES INHERENTLYUNSTABLE

vegetationtakestimetobecomeeffective

SHEET‐FLOW

Groundcovers:3to5yearsShrubs:4to10yearsTrees:7to15years

vegetationbecomesmoreeffectiveovertime

COIREROSION‐CONTROLMAT&NATIVEPLANTINGS

use NATIVE plant materials in all

biostructural projects

better stormwater & erosion control

more salt‐tolerant than ornamentals

better rootingcapability

more droughtresistant   

provide better wildlife habitatRosanutkana

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PlantForMultipleCanopyLevels

includebothevergreen&deciduousplants

PLANTFORSUCCESSION(nativeecosystemplantcommunitysuccession&developmentovertime)

overstorycanopy

understory

groundcovers

planning,design,permitting&installationofbio‐structuralprojectsrequirespecialskills

SEATTLEPROJECT,2014 BELLINGHAMPROJECT,2001

somesitesarenotabletobestabilized

STRAITOFJUANDEFUCACLALLAMCOUNTY

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ELWHARIVERREVEGETATIONSITE,NOV2013

thankyou

www.greenbeltconsulting.com

BIO-STRUCTURAL ENGINEERINGFOR EROSION CONTROL & SLOPE STABILIZATION

WITH NATIVE VEGETATION AS A KEY COMPONENT

ElliottMenasheGreenbeltConsulting www.greenbeltconsulting.com

combines:artscienceengineering&ecologicalrestoration

INTRODUCTIONTOLANDSCAPESONTHEEDGEdesign&implementation

ofprojectsonPugetSoundshorelines

&urbanravinesNov15‐162016