Homeowner Resource Packet

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Introduction

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ABOUT WASHINGTON CONSERVATION DISTRICT

ABOUT THIS GUIDE

WHAT’S INSIDE?Raingarden Design Templates and Plant Lists3Common Plants For Raingardens and Buff ers7Raingarden Cross-Sectionsand Construction Details11Materials and Labor Estimations15Frequently AskedQuestions17Helpful Links and Resources

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Brown's

Creek

Va lle y Creek

Brown's Creek

Brown's

Creek

Va lle y Creek

Brown's Creek

Hwy 36

694

I-35

Fore

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Man

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Ave

Man

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Ave

Nor

rell

Ave

202nd Ave N

170th St N

Dellwood Rd

Scandia Trail

St C

roix

Trai

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60th St N

34th Ave N

Bailey Rd

St Croix Trail

St C

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Tra

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Hwy 61

BCWD

CMSCWD

RCWD

CLFLWD

MSCWMO

VBWD

SWWD

RWMWD

Our mission is to enhance, protect, & preserve the natural resources of Washington County through

conservation projects, technical guidance, & educational services.

This guide has been developed to provide you with the information you need to install a raingarden or other soil/water Best Management Practice.

The Washington Conservation District is a local unit of government dedicated to land and water conservation. We are established under state statute and governed by an elected board. There are 8 watershed districts within the county that have education and outreach programs dedicated to clean water projects.

Enclosed you will fi nd sample raingarden designs, plant palettes, and construction details to help with the installation of your garden. Also enclosed is contact information for local government partners, an FAQ sheet, and a list of resources that you may fi nd helpful in your mission to protect our soil and water resources on your property.

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Partners + Contacts

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WATERSHED ORGANIZATIONS

(BCWD) Brown’s Creek Watershed District

(CMSCWD) Carnelian-Marine St. Croix Watershed District

(CLFLWD) Comfort Lake Forest Lake Watershed District

(MSCWMO) Middle St. Croix Watershed Management Organization

(RMMWD) Ramsey Washington Metro Watershed District

(RCWD) Rice Creek Watershed District

(VBWD) Valley Branch Watershed District

(SWWD) South Washington Watershed District

www.bcwd.org

www.cmscwd.org

www.clfl wd.org

www.mscwmo.org

www.rwmwd.org

www.ricecreekwd.com

www.vbwd.org

www.swwdmn.org

FEDERAL, STATE, AND COUNTY CONTACTS

Board of Water and Soil Resources (MN)

Department of Natural Resources (MN)

National Park Service (US)

Pollution Control Agency (MN)

Washington County (County)

Washington County Parks (County)

Washington Conservation District (County)

www.bwsr.state.mn.us

www.dnr.state.mn.us

www.nps.gov

www.pca.state.mn.us

www.co.washington.mn.us

www.co.washington.mn.us/parks

www.mnwcd.org

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Raingarden TemplateT

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USE OF TEMPLATES

Common Name Genus species Planting Zone

Culver's Root Veronicastrum virginicum Bottom

Autumn Sneezeweed Helenium autumnale Bottom, Sides

Bebb's Sedge Carex bebbii Bottom, Sides

Grey-headed Conefl ower Ratibida pinnata Bottom, Sides

Great Blazing Star Liatris pycnostachya Bottom, Sides

Great Lobelia Lobelia siphilitica Bottom, Sides

Indian Grass Sorghastrum nutans Bottom, Sides

Purple Conefl ower Echinacea purpurea Bottom, Sides

New England Aster Symphyotrichum novae-angliae Bottom, Sides

Northern Blue Flag Iris versicolor Bottom, Sides

Sensitive Fern Onoclea sensibilis Bottom, Sides

Joe Pye Weed Eupatorium maculatum Bottom, Sides

Swamp Milkweed Asclepias incarnata Bottom, Sides

White Turtlehead Chelone glabra Bottom, Sides

Wild Bergamot Monarda fi stulosa Bottom, Sides

Rattlesnake Master Eryngium yuccifolium Bottom, Sides

Lady Fern Athyrium felix-femina Bottom, Sides

Soft Rush Juncus effusus Bottom, Sides

Heart Leaved Alexanders Zizia aptera Sides, Top

Little Bluestem Schizachyrium scoparium Sides, Top

Stiff Goldenrod Solidago rigida Sides, Top

Butterfl yweed Asclepias tuberosa Top

Prairie Dropseed Sporobolus heterolepis Top

Prairie Smoke Geum trifl orum Top

Purple Prairie Clover Dalea purpurea Top

Alum Root Heuchera sanguinea Top

BOTTOM SIDES TOPSIDESTOP

Raingarden Planting ZonesCross-section

TOP: Reserved for dry-loving species that do not tolerate standing water. Sedums, herbs, and shorter prairie grasses work well. Heights should be shorter.

TOP:

SIDES: Versatile species from mesic upland and wet meadows work well here. Conefl owers, medium height grasses, and Asters are common.

SIDES:

BOTTOM: Select taller species that can tolerate both 6-12” of standing water for up to 48 hours as well as tolerate periods of prolonged drought. Wet meadow natives like Joe Pye Weed, Sneezeweed, and Switchgrass are good fi ts.

BOTTOM:

The following templates are meant to aid in plant selection for a raingarden according to light and water needs. Each template has plants (and selected substitutes) that are chosen for Full Sun, Part Sun, and Shade locations. The diagram below shows the typical zones to consider for plant selection and the list is sorted according to these zones. Refer to the Links and Resources page for more resources on plant selection and design.

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Raingarden Template

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FULL SUN PALETTENotes for Construction:*Gardens are assumed to be a 6” ponding depth (perform infi ltration test for accurate depth).*Plants are generally spaced 18”, but grasses and shrubs will need more spacing and shorter species on the edges will often be 12”-18”.*Plants chosen are recommendations. Always check plant soil, water, and light requirements before purchasing.*These plans are for 100 sq ft garden. SeeMaterials and Instalaltion Costs pages for multipliers to fi t your garden needs.

8+ hours of Sun

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1) Prairie Smoke (Geum trifl orum)Substitutes: June Grass, carpet-forming sedums, or small rock garden types of species2) Bebb’s Sedge (Carex bebbii)Substitutes: Sprengell’s Sedge, Fox Sedge, Tussock Sedge, Meadow Blazing Star (Liatris ligulistylis)3) Blue Flag Iris (Iris versicolor)Substitutes: Soft Rush, Green Bulrush, DO NOT USE Yellow Iris (Iris pseudacorus)4) Purple Conefl ower (Echinacea purpurea)Substitutes: Pale Purple Conefl ower, Echinacea cultivars (eg, ‘Magnus’, ‘White Swan’)5) ‘Autumn Magic’ Chokeberry (*shrub) Aronia melanocarpa ‘Autumn Magic’Substitutes: False Blue Indigo, ‘Little Joe’ Joe Pye Weed, small Viburnum shrubs6) ‘Shenandoah’ Switchgrass (Panicum virgatum ‘Shenandoah’)Substitutes: Karl Foerster Grass, Indian Grass (Sorghastrum nutans)7) ‘Autumn Joy’ Sedum (Sedum ‘Autumn Joy’)Substitutes: ‘Matrona’ Sedum, Salvias (‘May Night’ or ‘Caradonna’), Daylily (‘Happy Returns’)8) Butterfl y Milkweed (Asclepias tuberosa)Substitutes: Little Bluestem, ‘Moonbeam’ Coreopsis, ‘Goldsturm’ Black Eyed Susan9) Prairie Dropseed (Sporobolus heterolepis)Substitutes: Catmint (‘Walkers Low’), Silky Aster, New England Aster (‘Purple Dome’)

Raingarden TemplatePART SUN PALETTE

Notes for Construction:*Gardens are assumed to be a 6” ponding depth (perform infi ltration test for accurate depth).*Plants are generally spaced 18”, but grasses and shrubs will need more spacing and shorter species on the edges will often be 12”-18”.*Plants chosen are recommendations. Always check plant soil, water, and light requirements before purchasing.*These plans are for 100 sq ft garden. See Materials and Installation Costs pages for multipliers to fi t your garden needs.

5-8 hours of Sun

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1) Bugleweed (Ajuga reptans)Substitutes: Gaillardia (Blanket Flower), Woods Blue Aster, Wild Geranium2) Bebb’s Sedge (Carex bebbii)Substitutes: Sprengell’s Sedge, Fox Sedge, Meadow Blazing Star 3) Blue Flag Iris (Iris versicolor)Substitutes: Soft Rush, Green Bulrush, DO NOT USE Yellow Iris (Iris pseudacorus)4) ‘Hot Lips’ Turtlehead (Chelone obliqua ‘Hot Lips’)Substitutes: Turtle Head, Culvers Root, Blue Lobelia, Cardinal Flower5) ‘Autumn Magic’ Chokeberry (*shrub) (Aronia melanocarpa ‘Autumn Magic’)Substitutes (non-shrub): False Blue Indigo, ‘Little Joe’ Joe Pye Weed, small Viburnum shrubs6) ‘Shenandoah’ Switchgrass (Panicum virgatum ‘Shenandoah’)Substitutes: Karl Foerster Grass, Deschampsia (not tall)7) ‘Palace Purple’ Coral Bells (Heuchera spp.)Substitutes: Any cultivar of Coral Bells or native Alum Root (Heuchera sanguinea)8) Heartleaf Bergenia (Bergenia cordifolia)Substitutes: Bleeding hearts, Lady’s Mantle9) ‘Purple Dome’ New England Aster (Aster novae-angliae ‘Purple Dome’)Substitutes: Daylily (any short cultivar), Cranesbill (Geranium sanguineum, or any cultivar)

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Raingarden TemplateFULL SHADE PALETTE

Notes for Construction:*Gardens are assumed to be a 6” ponding depth (perform infi ltration test for accurate depth).*Plants are generally spaced 18”, but grasses and shrubs will need more spacing and shorter species on the edges will often be 12”-18”.*These plans are for 100 sq ft garden. See Materials and Installation Costs pages for multipliers to fi t your garden needs.

<5 hours of Sun

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1) Pennsylvania Sedge(Carex pennsylvanica)Substitutes: Blue Sedge, Dwarf Goatsbeard, Carpet Bugle, Tiarella, Wild Ginger2) Bebb’s Sedge (Carex bebbii)Substitutes: Sprengell’s Sedge, Fox Sedge3) Sensitive Fern (Onoclea sensibilis)Substitutes: Lady Fern, Ostrich Fern4) ‘Hot Lips’ Turtlehead (Chelone obliqua ‘Hot Lips’)Substitutes: Blue Lobelia, Cardinal Flower5) Ligularia ‘Desdemona’ (Ligularia dentata‘Desdemona’)Substitutes: ‘Little Rocket’ Ligularia, large blue Hostas (careful...deer candy)6) Bugbane (Cimicifuga racemosa)Substitutes: ‘Hillside Black Beauty’ Bugbane, ‘Rocket’ Ligularia, Goatsbeard (full size, not dwarf )7) Bleeding Hearts (Dicentra spectabilis)Substitutes: Bleeding Hearts (any larger cultivar), Solomon’s Seal (native or variegated cultivar)8) ‘Palace Purple’ Coral Bells (Heuchera spp.)Substitutes: Any cultivar of Coral Bells, Heartleaf Bergenia 9) Jacob’s Ladder (Polemonium reptans)Substitutes: Astilbe (any cultivar), Alpine/Dwarf Columbine (any cultivar) 10) Maidenhair Fern (Adiantum pedatum)Substitutes: Japanese Painted Fern, ‘Ghost’ Fern, Brunnera (select zone-hardy cultivars)

Common Raingarden Plants

FernsShown: Sensitive FernOnoclea sensibilis

Iris Shown: Blue Flag IrisIris versicolor

RushesShown: Soft BulrushJuncus effusus

Native GrassesShown: Indian GrassSorghastrum nutans

SedgesShown: Sprengell’s SedgeCarex sprengellii

ShrubsShown: Bush HoneysuckleDiervilla lonicera

ShrubsShown: Black ChokeberryAronia melanocarpa

ShrubsShown: Red Twig DogwoodCornus sericea

Native GrassesShown: Prairie DropseedSporobolus heterolepis

SedgesShown: Fox SedgeCarex vulpinoidea

Native GrassesShown: Little BluestemSchizachyrium scoparium

Cultivated GrassesShown: Karl FoersterFeather Reed Grass

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Common Raingarden Plants

GroundcoversShown: Wild geraniumGeranium maculatum

MonardaShown: Bee BalmMonarda fi stulosa

EryngiumShown: Rattlesnake MasterEryngium yuccifolium

EupatoriumsShown: Joe Pye WeedEupatorium purpureum

Conefl owersShown: Purple Conefl ower & Goldsturm Conefl ower

BlazingstarsShown: Meadow BlazingstarLiatris ligulistylus

SedumsShown: ‘Autumn Joy’ Sedum

GroundcoversShown: Carpet BugleAjuga reptans

AstersShown: ‘Purple Dome’New England Aster

LobeliasShown: Blue LobeliaLobelia siphilitica

TurtleheadsShown: ‘Hot Lips’ TurtleheadChelone obliqua

Coral BellsShown: ‘Palace Purple’Coral Bells

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Useful Native PlantsCOMMON PLANTS FOR NATIVE PLANTINGS

Genus species Common Name Light HabitatAchillea millefolium Yarrow S, PS Prairie, Woods

Agastache foeniculum Anise Hyssop S, PS Prairie

Allium stellatum Prairie Onion S, PS Prairie

Amorpha canescens Leadplant S, PS Prairie

Anaphilis margaritacea Pearly Everlasting S, PS Prairie, Woods

Asclepias incarnata Swamp Milkweed S, PS Shore

Asclepias tuberosa Butterfl y Milkweed S, PS Prairie

Aster cordifolius Heartleaf Aster S, PS Prairie

Aster laevis Smooth Aster S, PS Prairie, Woods

Aster novae-angliae New England Aster S, PS Shore

Aster sericeus Silky Aster S, PS Prairie

Baptisia australis Blue False Indigo S, PS Prairie

Campanula rotundifolia Harebell S, PS Prairie, Woods

Chelone glabra Turtlehead S, SH Shore

Coreopsis palmata Prairie Coreopsis S, PS Prairie

Dalea purpurea Purple Prairie Clover S, PS Prairie

Echinacea purpurea Purple Conefl ower S, PS Prairie

Eryngium yuccifolium Rattlesnake Master S, PS Prairie

Eupatorium perfoliatum Boneset S, PS Prairie, Shore

Eupatorium purpureum Purple Joe-Pye Weed PS, SH Prairie, Woods

Eurybia macrophylla Big Leaf Aster S, PS, SH Woods

Fragaria virginiana Wild Strawberry S, SH Prairies Woods

Gaillardia aristata Gaillardia/Blanket Flower S, PS Prairie

Geum trifl orum Prairie Smoke S, PS Prairie

Helenium autumnale Sneezeweed S, SH Shore

The following list is to be used for native plantings. These can be located above shorelines (in the upland areas above the Ordinary High Water Mark), for use in the extension of your own garden areas, or where increased native species are desired (woodlands or fallow fi elds). See the Resources page for more extensive information regarding native plantings and habitat creation.

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Useful Native PlantsCOMMON PLANTS FOR NATIVE PLANTINGS

Heliopsis helianthoides False Sunfl ower S, PS Prairie, Shore

Iris versicolor Northern Blue Flag Iris S, PS Shore

Liatris aspera Rough Blazing Star S, PS Prairie, Woods

Liatris pychnostachya Thick Spike Blazing Star S, PS Prairie, Shore

Lobelia cardinalis Cardinal Flower S, PS Shore

Lobelia siphilitica Great Blue Lobelia S, PS Shore

Monarda fi stulosa Bergamot S, PS Prairie, Woods

Phlox pilosa Prairie Phlox S, PS Prairie

Pycnanthemum virginianum Mountain Mint S, PS Prairie, Shore

Ratibida pinnata Yellow Conefl ower S, PS Prairie

Rudbeckia subtomentosa Sweet Black Eyed Susan S, PS Prairie, Shore

Solidago nemoralis Grey Goldenrod S, PS Prairie

Solidago rigida Stiff Goldenrod S, PS Prairie, Shore

Thalictrum dasycarpum Purple Meadow Rue S, PS Prairie, Shore

Tiarella cordifolia Foamfl ower S, SH Prairie

Tradescantia ohiensis Spiderwort S, SH Prairie, Shore, Woods

Veronicastrum virginianum Culver’s Root S, SH Prairie, Woods

Zizia aurea Golden Alexanders S, PS Prairie, Woods

Andropogon gerardii Big Bluestem S, PS Prairie, Woods

Bouteloua curtipendula Side Oats Grama S, PS Prairie, Woods

Bouteloua gracilis Blue Grama S, PS Prairie

Bromus kalmii Kalm’s Brome S, PS Praire, Woods

Calamagrostis canadensis Blue Joint Reedgrass S, PS Prairie, Shore

Carex bebbii Bebb's Sedge S, SH Prairie, Shore

Carex brevior Plains Oval Sedge S, SH Prairie, Shore

Carex pennsylvanica Pennsylvania Sedge S, SH Prairie, Woods

Carex vulpinoidea Fox Sedge S, SH Prairie, Shore

Koeleria macrantha June Grass S, PS Prairie

Panicum virgatum Switch Grass S, PS Prairie, Shore

Schizachyrium scoparium Little Bluestem S, PS Prairie

Sorghastrum nutans Indian Grass S, PS Prairie

Spartina pectinata Prairie Cordgrass S, PS Prairie, Shore

Sporobolus heterolepis Prairie Dropseed S, PS Prairie

Amelanchier spp. Serviceberry (many species) S, PS, SH Prairie, Woods, Shore

Aronia melanocarpa Black Chokeberry S, PS Woods

Cornus sericea Red Osier Dogwood S, PS, SH Shore, Woods

Diervilla lonicera Dwarf Bush Honeysuckle S, PS, SH Woods

Physocarpus opulifolius Ninebark S, PS Prairie, Woods

Viburnum dentatum Arrowwood Viburnum S, PS, SH Shore, Woods

Genus species Genus species Light Habitat

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Raingarden DetailsRAINGARDEN CONSTRUCTION Typical Cross Section

Incorporate 3” organic compost

Set edging

flush with turf

Set edging flush with turf

Set berm at least 1” lower than

inlet of garden

Set inlet edge at least 1” higher

than berm/overflow elevation

Existing Soil

2”-3” shredded hardwood mulchTypical Ponding depth 6” deep. Do not exceed 12” deep.eep

4” to 12”

Ponding Depth: Typical depth is 6”. Depth should be 4” -12”, depending on size of capture area and infi l-tration rate of soils.

Soil Excavation and Amendments: Call Gopher One before you dig. Overdig past the ponding depth by 3”. Loosen soils beneath to a 1’-2’ depth. Add 3” of compost to loosened soils and mix in. After mixing soil, add a 3” deep layer of shredded hardwood mulch.

Berm: Set the overfl ow berm at least 1” lower than garden inlet. This will allow for overfl ow to a safe place rather than back towards a home or other structure.

Armoring: Where fl ows may be heavy entering or overfl owing from the garden, insert larger cobbles or riprap into fl owpath to reduce the energy of the fl owing water. This will help to prevent erosion and scouring issues at high fl ow areas of the garden.

Edging: Set edging fl ush with turf. Steel or paver edging lets water pass into garden. Vinyl edging will need to have notches cut in top lip of edging to let water pass into garden.

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Overfl owover berm

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Flow from pipe and patio

Underground PipeAtrium Grate

Site garden >10’ from structures

Raingarden DetailsRAINGARDEN (WITH WALL) CONSTRUCTION

Typical Cross Section

Boulder Wall Natural Stone Wall Segmental Wall

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Compacted BaseOverdig and loosen 1-2 feet of sub soils

Incorporate 3” organic compost

Set edging flush with turf

Set berm at least 1” lower than

inlet of garden

Overflow Pipe and Riser

Existing Soil

2”-3” shredded hardwood mulchTypical Ponding depth 6” deep. Do not exceed 12” deep.

Bury base course halfway

3” backfill pea-rock

Geotextile fabric

4” to 12”

Retaining Wall: Use either natural stone or segmental retaining wall blocks. Do not exceed 4’ height without engineer approval. Stack at 15o angle into slope. Add small swale (2” deep by 6” wide) atop wall to move water away from back of wall. Water does not enter garden from top of wall.

Wall Base and Backfi ll: Compact 6” of subgrade (or compact Class V gravel) for wall footing. Also compact 9”-12” of soil in front of wall before sloping into raingarden. *DO NOT COMPACT BASE OF RAINGARDEN FLOOR.*

Geotextile Fabric: Line bottom of base course and back side of wall with geotextile fabric.

Ponding Depth: Typical depth is 6”. Depth should be 4” -12”, depending on size of capture area and infi ltration rate of soils.

Soil Excavation and Amendments: Call Gopher One before you dig. Overdig past the ponding depth by 3”. Loosen soils beneath to a 1’-2’ depth. Add 3” of com-post to loosened soils and mix in. After mixing soil, add a 3” deep layer of shredded hardwood mulch.

Berm: Set berm at least 1” lower than garden inlet. This will allow for overfl ow to a safe place rather than back towards a home or other structure.

Overfl ow Pipe: Install overfl ow pipe for native soils that do not drain well. Set upright pipe in garden 2” -3” above bottom of garden and at least 2” below top of berm. Install cap to this portion. Attach upright to an elbow and attach elbow to perforated draintile. Run tile from garden, under berm, and daylight the pipe to a safe area for accepting overfl ow water.

Outlet: Outlet can elbow up to a popup riser or can be a straight pipe that daylights out of berm or further downhill. Make sure popup elevation is lower than raingarden fl oor. Ensure pipe fl ows to safe area for ac-cepting overfl ow water.

Edging: Set edging fl ush with turf. Steel or paver edging lets water pass into garden. Vinyl edging will need to have notches cut in top lip of edging to let water pass into garden.

Water enters through pipe in wall or from side of garden

Raingarden DetailsCONVEYANCE TOOLS AND TECHNIQUES

Excavated soil used to build up edges (3:1 slope)

Decorative boulders as desired

3”-6” depth of largerrgl

cobbles as desiredd

Rock edging

alternative Edges use larger cobbles (3”-6”)

Fabric or plastic liner

(depending on needs)p g

Trench in and bury edges of liner

at top of slope (min. 3” deep)

Set edging

flush with turf

Existing Soil3” depth of 3/4”-2” rock

Atrium Grate Atrium GrateShreddedHardwoodMulch

Pop-up Emitter

Solid or Perforated Pipe

Pop-up EmitterPop up Emitter

Outfall Types and Protection

Dry Creek Bed Section and Notes

Creek Bed Dimensions: Typical dimensions vary. Common rule of thumb is to make the bot-tom two to three times wider than the height. A typical depth for a home is 9“ (6” of rock will fi ll bottom to make it appear to be 3“ deep).

Soil Excavation and Amendments: Dig down to desired creek bed depth. Compact soil with feet or tamper to create solid and smooth foundation for liner and rock.

Slopes and Bed Edges: Set edges of creek bed at least 2” higher than existing grade to keep water in channel. Final slope of edges should be 3:1.

Liner: Two choices for liner, depending on how water is conveyed. 1) Geotextile fabric liner - If you desire water to infi ltrate into the soils during transit to the water’s fi nal destination (ie, raingarden). 2) Poly/Plastic liner - Use a thicker, imper-meable liner if you do not want water to weep into the ground during transit (so the raingarden gets all the water or if the creek bed is close to a structure).

Edging: Set edging fl ush with turf. Steel edging is preferred, but rock edging will also work to fi t with design needs. If using rock, dig a 3” deep trench and fi ll it with smaller rock and decorate the top of trench with larger rock as desired. This trench will be your weed barrier.

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Raingarden DetailsCONVEYANCE TOOLS AND TECHNIQUES

Scour and Erosion Prevention: At the base of any pipe that enters

a garden, armor the outlet with small cobbles, sized large enough

so they do not move with the force of water coming from the pipe.

This will help reduce scouring and erosion issues when water enters

the garden. The same concept can be applied to points of overflow

(like the berm) where water flow is concentrated and erodes soil.

45˚ Angle Downspout Extension

Catch Basin with Grate Cover

Minimum 2” Se” papp ration Between

Downspout and Catch Basin

Position Grate Just Above Existing Grade

4” Minimum”

4” Perfo” rated/Solid/Corrugated/PVC Draintile

Width Varies

gHeight Varies

6” Compacted Class Vor Compacted Parent Soil

Maintain positive slope to assure proper drainagep p u e proper drainage

Outfall Protection Notes:

Catch Basin Detail and Notes

Downspout Alignment: Downspout may need to be cut back and fi tted with a 45˚ angle downspout extension. Downspout shoud be aligned with center of catch basin for maximum capture. Leave 2” to 4” of space between the downspout and catch basin to allow for leaves and other debris to wash free (minimizing clogging)

Catchbasin Excavation: Over-excavate 6” past the depth of the catchbasin and backfi ll with compacted Class V gravel or with the existing parent soils.

Catchbasin Elevation: Catch basin should be set slightly above the surrounding grade to minimize poten-tial for sediment washing into basin (unless catchbasin is capturing overland fl ow as well as downspout fl ow). Catch basin should also be set a minimum of 2” above the overfl ow elevation of a raingarden to prevent over-fl owing out of the catch basin and against the foundation of the house.

Draintile Selection: Choose draintile type to fi t drainage needs. PVC and non-perforated draintile are used to convey all water to a single point. Perfo-rated draintile will allow some water to infi ltrate while water is in transit to its outlet point (raingarden, swale, etc). Account for nearby structures and vulnerability to water damage if choosing perforated draintile. 4“ and 6” pipe diameters are typical in residential set-tings. Size catchbasin fi ttings accordingly. Fit perfo-rated pipes with nylon sock.

Draintile Installation Ensure pipe is slope to outlet destination to maintain proper drainage (mini-mum. 2% slope=2“ drop every 100”). Attach pipe to catchbasin. Place pipe in trench and backfi ll beneath pipe until proper slope is achieved (and no sags in pipe). Backfi ll rest of trench with excavated soil and maintain at least 4” of soil above pipe to minimize potential to crush pipe. Replace top of trench with grass seed or sod.

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Materials Cheat SheetMATERIALS LIST

CONVERSIONS

Material CostMulch(3” deep double-shredded hardwood)

Bulk: $25-35/ydBag/Bale: $45-65/yd

Compost(organic compost or 30/70 compost/sand mix)

Bulk: $20-30/ydBag: $40-60/yd

Wall Stone Field Stone: $6-9/sfNatural Cut: $9-20/sfManufactured Block: $4-12/sf

River Rock (creek beds/French Drains) $35-75/ydEdging Vinyl: $0.40-0.70/lf

Steel: $3-5/lfBrick/Paver: $0.50-3.00/lf

Native Seed $0.03-0.07/sfRip-Rap (4”-9” Limestone or Trap Rock) $45-80/tonNative Plants Plugs: $0.75-2.00 each

4” tubs: $1.60-3.50 eachCultivars of Native Plants Plugs/4”: $1.00-3.50 each

#1 Pots: $7-14 each

Material ConversionsMulch (3” deep)1 cu yd every 108 sq ft1 cubic yard = 27 cubic feet

(bags of mulch are often 2 cf ) 13.5 bags = 1 cubic yard

Compost Amendment0.5 cu yd every 100 sq ft

(bags of compost are often 0.5 cf )54 bags = 1 cubic yard (hint: buy bulk)

Plant Spacing (for grid spacing)To the right are the number of plants needed for a 100 sq ft garden at various spacings.

for 6” spacing; 400 plantsfor 12” spacing; 100 plantsfor 18” spacing; 45 plants for 24” spacing; 25 plantsfor 36” spacing; 11 plants

Slope = Rise/Runex: 3’rise/10’run = .333 = 33.3% slope (or 3:1)

Slope x Run = RiseRise / Slope = Run

sf = square feetcf = cubic feet

lf= linear feetyd = cubic yard

pg 15

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Installation Costs

WHAT VARIABLES AFFECT COST?

COST ESTIMATESDo-It-Yourself vs. Contractor

Installed Item DIY Cost Contractor Cost Raingarden (no underdrain)

$2-$7/sf $6-$13/sf

Raingarden (with draintile and catchbasin assembly)

$6-$10/sf $12-$17/sf

Retaining Wall $7-$30/sf $35-$60/sf

Permeable Pavers Use Contractor $14-$19/sfRainbarrel $20-$150 each Self InstallDry Creek Bed $2-$5/sf $5-$8/sfShoreline Buff er $2-$6/sf $5-$8/sfShoreline Armoring $3-$8/sf $5-$12/sfNative Planting (plugs) $2-$6/sf $5-$8/sf Native Planting (seeding) $500/acre $1,500/acre

Raingardens: How deep are you excavating? How much of the sub-soil are you amending or replacing with new compost? How big are your plants (plugs vs. 1 gallon pots)? Is there draintile and rip-rap needed? Is a curb-cut involved?

Access and Disposal: Contractors will always consider ease of access in bidding a project. The harder it is to get in and work, the longer the project will take. Also consider reuse of soils and excavated materials onsite to eliminate waste and disposal fees.

Shorelines and Native Plantings: What weeds are present and need to be managed prior to install (and for how long)? How intensive is the wave action or erosion on a shoreline? Are additional erosion control materials or biologs needed to complete the project?

Rainbarrels: What type of barrel (plastic drum vs wine cask)? How large is the unit? Is there so much water that you will need more than one rainbarrel? What peripherals are being used (screen tops, downspout realignments, overfl ow items, shutoff or diversion valves)?

Retaining Walls: What stone are you using (block is often cheaper than natural stone)? Is the wall drystack or is it mortar? Is it taller than 3’ (wallas taller than 3’ need review by a structural engineer or should be broken in to liftmultipl liufts of 3’ or less feet).

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FAQ’sFREQUENTLY ASKED QUESTIONS

Before you ask: Look to our Blog! The Washington Conservation District has a Blog that frequently showcases articles on our most commonly asked questions. The blog link can be found at www.mnwcd.org

Also, look to our Partners page and our Links and Resources page for helpful links to some of your most commonly asked questions. If these do not help you fi nd your answer, the Washington Con-servation District staff are always available to assist you and your needs.

Q: How deep should my raingarden be?

A: Typical sizes are 6” deep for residential spaces. If your soils drain fast enough (>2” per hour), and you have a lot of area to capture in your garden you could probably make it 9” deep. You should never have to go deeper than 9-12” deep. PERFORM AN INFILTRATION TEST TO SEE HOW FAST YOUR SOIL DRAINS.

Q: How do I perform an Infi ltration Test?

A: Dig a coffee can sized hole in the area you want to put the raingarden (8” deep by 8” round). Fill the hole to the top with water and let it drain completely. Fill it once more and let it drain again. Fill it a 3rd time and mark the water level with a stick or toothpick. Come back one hour later and measure how far down from that marker the water has drained in that hour. Then multiply that number by 24 (hours in a day). This will determine if you can at least have a 6” deep garden. If the number is less than 6, your soils are likely heavy clay or extremely compacted and you may want to make a shallower garden or none at all. If your soils do not drain well, contact a us for a second opinion. EXAMPLE: You measure the water dropped 4” in one hour. Multiply 4 x 24 = 96. This does not mean your garden should be 96” deep. It means your soils drain very well and a 6” or even 9” deep garden should behave wonderfully.

Q: How do I size my raingarden?

A: Take the Area (sq ft) of impervious area (like roofs or driveways) and divide it by the raingarden depth that you wish to make your garden. EXAMPLE: 480 sq ft of roof area is draining to a 6” deep raingarden = How big should my raingarden be........ 480/6 = 80 sq ft

Q: How often should I weed my rainarden?

A: A general rule of thumb is to weed around the summer holidays; Memorial Day (cool season weeds), 4th of July (warm season weeds), and Labor Day (late summer touchup). The fi rst couple of years will require a little more intensive maintenance to stay ahead of weeds on that freshly broken soil. Once the plants are mature and the soil settles back in, weeding becomes less frequent (if you have stayed on top of the weeds in years 1 and 2).

Q: Should I water my rainarden?

A: Only water during the establishment period for new plants and during periods of prolonged drought. One feature of a raingarden is that you shouldn’t have to water very often once plants are established.

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Links and ResourcesCOMMON LINKS AND RESOURCES

Raingardens and Stormwater Management:

Shorelines, Native Buff ers, and Habitat Restoration:

Books: Landscaping for Wildlife and Water QualityCarrol L Henderson, Carolyn J Dindorf, Fred J RozumalskiMinnesota’s Bookstore, MN

‘The Blue Thumb Guide to Raingardens: Design and Installation for Homeowners in the Upper MidwestRusty Schmidt, Dan Shaw, David DodsBlue Thumb, MN www.bluethumb.org

MN Shoreland Management Resource GuideSustainable shoreland practices and morewww.shorelandmanagement.org

Master Gardener ProgramHoused in the U of MN Extension Program, you can access (or become) a Master Gardener.www1.extension.umn.edu/garden/master-gardener/

Wild OnesResource for native plants and their benefi tswww.wildones.org

Blue ThumbRainscaping resources and plant fi nderwww.bluethumb.org

MN Department of Natural ResourcesPrairies: www.dnr.state.mn.us/prairierestorationShorelines/Lakes: www.dnr.state.mn.us/lakesPlants: www.dnr.state.mn.us/plantsPermitting (shores/streams): www.dnr.state.mn.us/permits/water/answers

University of MN Extension ServiceResearch-based information from stormwater to gar-dening to conservation practiceswww.extension.umn.edu

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WASHINGTON COUNTY WATERSHEDS

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Scandia Trail

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Bailey Rd

St Croix Trail

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Middle St CroixWatershedManagement Organization

Carnelian-Marine-St. CroixWatershed District

www.mscwmo.org

www.bwcd.org

www.cmscwd.org

www.rwmwd.org

www.vbwd.org

www.ricecreekwd.com

www.clfl wd.org

www.swwdmn.org

W CC D

Eight partner watersheds in the Washington Conservation District

Washington Conservation Districtwww.mnwcd.org

W CC D

1 3 8 0 W F R O N T A G E R D

H I G H W A Y 3 6

S T I L L W A T E R , M N 5 5 0 8 2

6 5 1 - 2 7 5 - 1 1 3 6 [ P H O N E ]

6 5 1 - 2 7 5 - 1 2 5 4 [ F A X ]

W W W . M N W C D . O R G

A S H I N G TON

ONSERVATION

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W CC D

1 3 8 0 W F R O N T A G E R D

H I G H W A Y 3 6

S T I L L W A T E R , M N 5 5 0 8 2

6 5 1 - 2 7 5 - 1 1 3 6 [ P H O N E

6 5 1 - 2 7 5 - 1 2 5 4 [ F A X

W W W . M N W C D . O R G

A S H I N G TON

ONSERVATION

I S T R I C T

Washington Conservation Center455 Hayward AvenueOakdale, MN 55128

phone: (651) 275-1136fax: (651) 275-1254