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RAINGARDENS

SusanKenzle,RLA,LI

WatershedProtectionDepartment

CityofAustin

Source:IowaNaturalResources

ConservationService

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WatershedProtectionDepartment(WPD)Missions:

water

quality

protection

and

erosion

control

Environmental Resource Management

Field Operations

Watershed Engineering

Watershed Policy and Planning

Design, implement & evaluate

engineered systems that reduce

pollution & erosion in our waterways.

Stormwater is a resource.

Water quality control retrofits

Stream restoration

DIVISIONS

Sustainable Stormwater

Solut ions Section

A rain garden is one of 7 green stormwater Infrastructure practices

recognized by WPD as eligible for water quality credit

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Whatand

Why

Whatand

Why1

Types

Types2

Plants

Plants3

Maintenance

Maintenance4

RainGarden

Topics

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Source:IowaNaturalResources

ConservationService

RAINGARDENS:

WHAT&WHY

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Rain

Garden:

What?Ashallow,vegetateddepressiondesignedtoabsorbandfilterrunofffromhardscapeslikeroads,sidewalks,driveways,roofs

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Rain

Garden:

Why? Toslowandcleanstormwater:reduceserosionandflooding,protectswaterqualitybyfilteringpollutants

Tominimize

potable

water

use

on

landscapes

Increasebaseflow increeksandgroundwaterrechargebyenhancingwaterinfiltration

into

the

soil

(rather

than

overland)

Tosupporthabitatforbirdsandbutterflies

Aesthetics

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Stormwaterenters

inlet Flooding

of

West

Bouldin Creek

intodevelopment

Erosion:WestBouldinCreek ErosionRepair:WestBouldinCreek

RainGarden:Why?

Tocapture

&

infiltrate

stormwater

runoff

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Source:treehugger.org

RainGarden:Why?

Tofilter

stormwater

and

remove

pollutants

fromvarioussources

Source:mass.gov/dep/water/resources

Source:delcocd.org Source:ristormwatersolutions.org

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Source:IowaNatural ResourcesConservation

Service

Source:greenhousecanada.com

RainGarden:Why?To

filter

stormwater

and

remove

pollutants

Plants&

soil

filter

and

removepollutants

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RAINGARDENS:

TYPES

Source:lowimpactdevelopment.org

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RainGardens:info.sourcesTheCityofAustinhastwo sourcesofinformationonRainGardens:

CityofAustinEnvironmentalCriteriaManual(ECM),Section1.6.7

Commercial,Multifamily, Civic,andPublicR.O.W.

GrowGreen(residential)

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RainGardens:Types

CityofAustinECM1.6.7HdetailsthreetypesofnonresidentialRain

Gardens:

FullInfiltration

PartialInfiltration

Filtrationwithnoinfiltration

ResidentialraingardensarenotgovernedbytheECM.

Fullinfiltration.

Source:liv.ac.uk

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RainGardensSOIL

&

WATER

INFILTRATION

Type ofexistingsoilanditsinfiltrationrateeffectsthetypeofraingarden.

Infiltrationtime: nonresidential(48hrs max.)andresidential(24hrs max.).

Nonresidentialraingardens:nativesoilorbiofiltration media,underdrain system.

Raingarden

growing

medium

characteristics:

Havesufficientwaterholdingcapacity;

Beabletosustainhealthymicroorganismpopulation.

InfiltrationTest

Source:watab.net

Simple Infiltration test Double ring Infiltration test

Simple

Cheap Direct Infiltration Rate

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Capturesandfullyinfiltratesrunoff

The

infiltration

capacity

of

the

site

soils

are

used

to

reducestormwaterrunoffvolumeandassociatedpollutants

Nounderdrain

RainGardenTypes FullInfiltration

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Capturesandtreatsrunoffthroughabiofiltration

bed,aspecial

soil

mix

Stormwaterexitsthisraingardenin2ways:

viaaraisedoutletpipe

byinfiltrationintotheunderlyingsoil

RainGardenTypes PartialInfiltration

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RainGardenTypesResidential

Nativesoil

Nounderdrain

or

connection

to

stormwater

system

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RainGardens:

Examples

Raingardensacrossthecitytakevariousforms

Commercial

Multifamily

Civic

PublicR.O.W.

Residential

FullInfiltration

PartialInfiltration

Filtration

FullInfiltration

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RainGardenExamplesCommercial

W34th Street

ZachScott

Theater3300

N

IH35

Aveda

Institute

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RainGardenExamples Multifamily

WildflowerTerrace,Mueller

WildflowerTerrace,

Mueller

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WestRGInfiltration

North

RGPartInfil.

EastRGPartInfil.

RainGardenExamplesCivicCity

of

Austin,

One

Texas

Center

Inundated Dry OTCRainGardenFacts:

1.5ACdrainagearea;

761,615galoftreated

stormwatertreatedinan

averageyear;

Approximately1,000lbs

totalsuspendedsolids

preventedfromentering

EastBouldin Creekand

LadyBird

Lake.

OTCRainGardenFacts:

1.5ACdrainagearea;

761,615galoftreated

stormwatertreatedinan

averageyear;

Approximately1,000lbs

totalsuspendedsolids

preventedfromentering

EastBouldin Creekand

LadyBird

Lake.WestRainGarden

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RainGardenExamplesCivic

NWRecreation

Center Stacy

Park

NWRecreationCenter

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RainGardenExamples R.O.W.

10th &Rio

Grande Grover

Ave.

ToddLane(future)

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RainGardensExamplesResidential

SolvitaTownhomes,HarmonAve.

BellamyResidence

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RAINGARDENS:

PLANTS

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RainGardens:Plants Plants

are

an

essential

component

theyfilterandcleanstormwater,and

stabilizethesoil

UseNativeoradaptedplants

UseDroughttolerantplants

Plantswithfibrousrootsystemsare

verybeneficial

Plant

roots

will

maintain

and

increase

soilporosity

Avoidplantsthatrequirewelldrained

soils

Diversityof

plant

types

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RainGardens:PlantsPLANT

INFORMATION

SOURCES NonresidentialfollowECM1.6.7C,Biofiltration

Turf grass (e.g., buffalo grass) Groundcovers

Small trees

Other with approval

Perennials

Shrubs Grasses, Sedges

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RainGardens:PlantsatOTCRainGardens

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RainGardens:PlantsatOTCRainGardens

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Source:sbgardendesign.wordpress.com

RAINGARDENS:

MAINTENANCE

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RainGardens:ConsiderMaintenanceDuringDesign Select

native

vegetation

whenever

possible.

Planvegetationthroughouttheentiregarden.

Plantsshouldpredominateovermulchorgravelsoil

stabilization.

Properplant

spacing

is

important.

Crushedgranite&othermaterialswithfinesshould

notbeusedastheycanclogthesystem,preventing

properdrainage.

Ifpedestriantrafficisexpected,providestepping

stonestodirectwalking.

Plantspinyvegetationalonggardenedgeto

discouragepedestrian

use.

Designthegardendepressiontobeasshallowas

possibletofacilitatemowingandreduceerosion.

Designwith

maintenance

in

mind.

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RainGardens:PostconstructionMaintenance

Keepcurbcut orotherinflowdeviceclearof

leaves,

trash,

sediment,

media

Inflow

Remove

excess

sediment

from

inside

inlet

to

allowproper

flow

into

rain

garden

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d

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RainGardens:PostconstructionMaintenancePlants

Pruneexcessive

growth

or

prune

for

plant

health Donotprunenativeplantsingeometricor

unnaturalshapes

Bunchgrassesnoshorterthan18

Mowsodforminggrasses

no

shorter

than

3

R i G d

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RainGardens:PostconstructionMaintenancePlants,Irrigation

Minimizeirrigationusebutkeepplantsadequatelywaterduringestablishmentanddrought

Checksystemsperiodicallyforproperfunction,leaks

Treestabilizationshouldberemoved

after1year

Girdledtrunk

R i G d

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RainGardens:PostconstructionMaintenance

Trash,Dead

Animals,

Standing

Water

Waterstandingforover48hrsmaysignalclogging&becomeamosquitobreedingarea

Removedeadanimals,petwaste,andtrashregularly

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QUESTIONS?

Source:IowaNaturalResources

ConservationService