OverviewBackground & BasicsDesign ConstraintsPlant SpeciesDesign ProcessRain Garden

OverviewCost AnalysisMaintenance IssuesSummary

What is a Rain Garden?A planted depression that allows rainwater

runoff to be absorbedIntended to prevent flooding and filter the

runoffMakes an otherwise dreary spot more

aesthetically pleasing

FunctionsDiverts runoff from impervious

paved surfaces or roofsHelps to remove pollutantsReplenishes groundwater

How does it work?Water enters rain garden through spout or

drain systemPonding occurs in rain garden lasting 1 to 2

daysWater seeps into the soil over time using the

vegetation as natural filtration

BenefitsAbsorbs up to 30% more

rainwater runoff than grass

Helps clean runoff of pollutants

Prevents flooding Provides a habitat for

wildlife, such as butterflies and birds

Rain Garden LocationLinden Hall provides optimum location for

rain gardenEasily accessible runoff

from roofRelatively low traffic areaHelp to increase aesthetics

in areaAlcove allows for more

controlled environment

Design ConstraintsFor safety reasons, the volume of the garden

should not be able to conceal a personAlong adjacent sidewalk expect crushing

snow so use plants that are able to bounce back in the spring

Lawn mower operators must be able to mow the remaining lawn with a 72 inch lawn mower without ever backing up

Plants have to be chosen from a predetermined list

Rain Garden VegetationSix plant types suitable for rain garden

Swamp Azelea (Rhododendron viscosum)Disco Belle Hibiscus (Hibiscus moscheutos)Cardinalis Flower (Lobelia cardinalis)Ruby Spice Summer Sweet (Clethra alnifolia)Sweetfern (Comptonia peregrina)Little Henry Sweet Spire (Itea virginica)

Chosen for their hardiness and aesthetic aspects

Rain Garden VegetationSwamp Azelea (Rhododendron

viscosum)Mature height: 2 – 8 ftPrefers saturated soilsHighly visible white

flowers

Disco Belle Hibiscus (Hibiscus moscheutos)Mature height: 6.6 ftShrub-like herbaceous perennialWhite or pink flowers with

crimson centers

Rain Garden VegetationRuby Spice Summer Sweet (Clethra alnifolia)

Mature height: 5 – 8 ftLong flowering and growing

periodYellow fragrant foliage

Cardinalis Flower (Lobelia cardinalis)Mature height: 2 -3 ftShade tolerantCardinal red flowers

Rain Garden VegetationSweetfern (Comptonia peregrina)

Mature height: 2 ftGood in coarse and medium

textured soilsGreen leaf blades

Little Henry Sweet Spire (Itea virginica)Mature height: 3 – 5 ftNative to NJ soilsYellow spiral leaves

Rain Garden DesignRain gardens are design using several

parametersAmount of Precipitation Imperviousness of Runoff areaAverage depth of water in rain garden

First, need to determine runoff depth

Curve Number (CN) is 98.

Rain Garden DesignNext, determine Runoff area for rain garden

Roughly 1500 ft2

Area x Runoff Depth = Runoff VolumeRunoff volume is the amount of

water the rain garden can holdFinally, get needed surface area

of rain garden

Runoff Area

Rain Garden DesignThe assumptions made for design:

Precipitation = 1 inchAsphaltic RoofAverage depth of rain garden = 4 inches

Final Design ResultsRunoff Area = 1500 ft2

Runoff Volume = 104.42 ft3

Rain Garden Surface Area = 313 ft2

Design for Linden HallOval shapedWill have sloping

sidesAverage depth is

4 inchesAccessible for

maintenance

A Closer Look

Swamp Azalea

Ruby Spice Summer Sweet

Sweetfern

Little Henry Sweetspire

Disco Belle Hibiscus

Cardinalis Flower

Cost AnalysisLabor being done by various student

organizationsMulch & Vegetation pricing based on rough

estimatesMiscellaneous Expenses covers construction

materials (i.e. piping, liners)Pricing Information

Construction Element Unit Cost ($/sq.ft.) Total Cost ($)

Vegetation 3.00 950.00

Mulch 0.30 95.00

Misc. Expenses 1.00 317.00

Total 1362.00

MaintenancePull weeds, especially

during the 1st yearWater 3 times a week

until established, and also during dry spells

Re-mulch (shredded hardwood won’t float away)

Cut back and trim as needed

What about mosquitoes?Mosquitoes need at least 7 days in standing

water to hatchA rain garden is not a pond, and will usually

dry out within a day or two

SummaryRain gardens help to reduce pollution and

divert runoffLinden Hall is an optimum location for a rain

gardenMajority of design and plant selection is

finishedRequire little maintenanceOverall, a rain garden is a low-cost,

aesthetically pleasing option for any university

Thank you for your time.Any questions?