michigan; rain garden design specifications for michigan conditions

8/3/2019 Michigan; Rain Garden Design Specifications for Michigan Conditions

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Rain Garden DesignRain Garden Design

Specifications for MichiganSpecifications for Michigan

ConditionsConditions

Donald Carpenter, Ph.D.Donald Carpenter, Ph.D.Lawrence Technological UniversityLawrence Technological University

January 11January 11thth, 2007, 2007Rouge River Watershed CommunitiesRouge River Watershed Communities


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Rain GardenRain Garden

((BioretentionBioretention Cell)Cell)

Filter Bed

Additional Storage

Underdrain

Ponding

In-situ soils


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Lathrup Village, MI

Courtesy of Lillian Dean


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Madison, Wisconsin

Courtesy of Roger Bannerman



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BioretentionBioretention (Rain Garden):(Rain Garden):

Design OverviewDesign Overview

Key feature for LID/conservation designKey feature for LID/conservation design

Focus on water quality volume (first flushFocus on water quality volume (first flush -- or 1 of rain) or 1 of rain)

Remove TSS (85%), nutrients (50%) , metalsRemove TSS (85%), nutrients (50%) , metals(95%), and hydrocarbons (80%)(95%), and hydrocarbons (80%)

Planting mix comprised of sand, topsoil, andPlanting mix comprised of sand, topsoil, and

compostcompost top with mulchtop with mulch Proper landscaping is essentialProper landscaping is essential

For site developmentFor site development stormwaterstormwater

management should include overflow drainsmanagement should include overflow drains Less than 1 ac total and acre imperviousLess than 1 ac total and acre impervious


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Design OverviewDesign Overview -- InfiltrationInfiltration Hydraulic conductivity of inHydraulic conductivity of in--situ soils is keysitu soils is key

Need inNeed in--situ soil information for infiltrationsitu soil information for infiltration HSG maps (soil type A (1 to 3 in/hr); B (0.5 in/hr); CHSG maps (soil type A (1 to 3 in/hr); B (0.5 in/hr); C

(0.2 in/hr); D (< 0.1 in/hr)(0.2 in/hr); D (< 0.1 in/hr)

Soil borings & laboratory testsSoil borings & laboratory tests Field infiltration testsField infiltration tests

Home testHome test 18 hole18 hole fill with water; drain, refill and recordfill with water; drain, refill and record

Improve infiltration by tilling, ripping or jettingImprove infiltration by tilling, ripping or jetting

Bottom should be 3 ft higher than seasonal g.w.t.Bottom should be 3 ft higher than seasonal g.w.t.


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Design OverviewDesign Overview -- SizingSizing

Minimum size is typically 10 ft by 20 ftMinimum size is typically 10 ft by 20 ft Minimum depth is 2.5 ftMinimum depth is 2.5 ft

PondingPonding depth is typically 6 to 18depth is typically 6 to 18

Recommend 24 to 48 hours to drain (< 72Recommend 24 to 48 hours to drain (< 72

hours)hours)

Infiltration (Infiltration (ii)) ii> 0.5 in/hr (or 1 in/hr) then basic design;> 0.5 in/hr (or 1 in/hr) then basic design; ii< 0.5< 0.5

in/hr needin/hr need underdrainunderdrain


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Results of 2005 LaboratoryResults of 2005 Laboratory

InvestigationInvestigation

Determine the storm w ater absorptionDetermine the storm w ater absorptioncapabilities of rain gardens of differentcapabilities of rain gardens of differentmixturesmixtures field capacity (water retained)field capacity (water retained)

permeability (water drained)permeability (water drained)

The 2005 laboratory study comparedThe 2005 laboratory study compared

fivefive different rain garden plantingdifferent rain garden plant ingmixturesmixtures

Evaluated the effect of differentEvaluated the effect of different

amounts of sand and topsoilamounts of sand and topsoil


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Field Capacity

0

20

40

60

80

100

120

140

160

100 / 0 / 0 80 / 20 / 0 60 / 40 / 0 0 / 100 / 0 35 / 35 / 30 80 / 10 / 10

Mixture Ratio

Perc

entagebyWeightofW

ater

Reta

ined Run 1

Run 2

Run 3


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0

20

40

60

80

100

120

140

0 10 20 30 40 50 60 70 80 90 100

% Sand Content by Volume

%ofW

aterRetained


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Permeability

0

10

20

30

40

50

60

100 / 0 / 0 80 / 20 / 0 60 / 40 / 0 0 / 100 / 0 80 / 10 / 10

Mixture Ratio

Permeability(in/hr)

Run 1

Run 2

Run 3


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0

10

20

30

40

50

60

0 10 20 30 40 50 60 70 80 90 100

% Sand Content by Volume

Perm

eability(in/hr)


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Implications for Rain GardenImplications for Rain Garden

DesignDesign

Mixture is going to dictate permeabilityMixture is going to dictate permeabilityand performance of rain gardenand performance of rain garden

I f the goal of the rain garden is toI f the goal of the rain garden is to

maxim ize water retention, than themaxim ize water retention, than theamount of sand or topsoil should beamount of sand or topsoil should belimited.l imited.

I f water needs to drain quicker intoIf water needs to drain quicker intopermeable layers of inpermeable layers of in--situ soils or intositu soils or intoanan underdrainunderdrain , then increase amount of, then increase amount of

sand in the mixture.sand in the mixture.


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Current ProjectCurrent Project

Developing technical assistance and guidanceDeveloping technical assistance and guidancematerials for rain garden designmaterials for rain garden design Design Guidelines for EngineersDesign Guidelines for Engineers

Literature ReviewLiterature Review

Michigan Specific InformationMichigan Specific Information

Two page public fact sheet for the regionTwo page public fact sheet for the region

Comprehensive information on local rain gardensComprehensive information on local rain gardens

Expand the investigation of permeability andExpand the investigation of permeability andretention of local rain gardensretention of local rain gardens Additional laboratory testsAdditional laboratory tests

Field measurementsField measurements


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Current ProjectCurrent Project

Questions and FeedbackQuestions and Feedback


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References & ResourcesReferences & Resources New York Stormwater Manual -

http://www.dec.state.ny.us/website/dow/toolbox/swmanual/

Minnesota Stormwater Manual-http://www.pca.state.mn.us/water/stormwater/stormwater-manual.html

USEPA Bioretention fact sheet -

http://www.epa.gov/owm/mtb/biortn.pdf Univ of Wisconsin DNR

http://clean-water.uwex.edu/pubs/home.htm#rain

LID Urban Design Tools -

http://www.lid-stormwater.net/ SOCWA Healthy Lawns and Gardens -

http://www.socwa.org/lawn_and_garden.htm

Rain Gardens of West Michigan -http://www.raingardens.org/Index.php

Prince Georges County, D.E.S. Bioretention -http://www.goprincegeorgescounty.com/Government/AgencyIndex/DER/ESD/Bioretention/bioretention.asp
http://www.pca.state.mn.us/water/stormwater/stormwater-http://www.goprincegeorgescounty.com/Government/Agencyhttp://www.goprincegeorgescounty.com/Government/Agencyhttp://www.pca.state.mn.us/water/stormwater/stormwater-

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