RAIN GARDEN TECHNICAL ASSISTANCE PROGRAM

RAIN GARDEN TECHNICALASSISTANCE PROGRAMRAIN GARDEN EDUCATION WORKSHOPHAMILTON TOWNSHIPMERCER COUNTYMay 2015water.rutgers.edu

What happens to the rain in our watersheds?It infiltrates into soils It runs off of rooftops and pavement It evaporates It is absorbedby plants

What is stormwater?Stormwater is thewater from rain ormelting snows that canbecome “runoff,”flowing over theground surface andreturning to lakes andstreams.

Pollutants Found in StormwaterSedimentSoil particlestransported fromtheir sourceBiochemical Oxygen Demand (BOD) Oxygen depleting materialØLeavesØOrganic materialToxics PesticidesØ HerbicidesØ FungicidesØ Insecticides Metals (naturally occurring insoil, automotive emissions/ tires)Ø LeadØ ZincØ Mercury Petroleum Hydrocarbons(automotive exhaust andfuel/oil)DebrisLitter and illegaldumpingNutrients Various types of materials that becomedissolved and suspended in water (commonlyfound in fertilizer and plant material):Ø Nitrogen (N)Ø Phosphorus (P)Bacteria/ PathogensOriginating from: Pets Waterfowl Failing septic systemsThermal StressHeated runoff,removal ofstreamsidevegetation

Impervioussurfaces

Impervioussurfaces

The Impact of Development onStormwater Runoff10%moredevelopment20%More impervioussurfaces30%55%more stormwaterrunoff

Connected or Disconnected?

The Solution

Rain GardensA rain garden is a landscaped, shallow depressionthat is designed to intercept, treat, and infiltratestormwater at the source before it becomes runoff.The plants used in the rain garden are native to theregion and help retain pollutants that could otherwiseharm nearby waterways.

Rain Gardens24 to 48 hours.Courtesy of City of Maplewood, MN

p. 28PARTS OF A RAIN GARDEN

SITE SELECTION & DESIGNPLANNING YOUR RAIN GARDEN

p. 17SITE SELECTION1. Next to a building with a basement, raingarden should be located min. 10’ frombuilding; no basement: 2’ from building2. Do not place rain garden within 25’ of aseptic system3. Do not situate rain garden in soggyplaces where water already ponds4. Avoid seasonably-high water tableswithin 2’ of rain garden depth5. Consider flat areas first – easier digging6. Avoid placing rain garden withindripline of trees7. Provide adequate space for rain garden

p. 18CALL BEFORE YOU DIG Free markout of underground gas,water, sewer, cable, telephone, andelectric utility lines Call at least 3 full working days, butnot more than 10 days, prior toplanned installation date Do not place rain garden within 5’horizontally and 1’ vertically fromany utilities

DRAINAGE AREACALCULATIONROOF 1DRAINAGE AREAROOF 2ROOF 1ROOF 1Surface Area (L1 x W) (L2 x W) (15’ x 20’) (10’ x 20’) (300’) (200’) 500 ft2LENGTH 2WIDTHLENGTH 1p. 20

p. 22CHECK YOUR SOIL Infiltration/Percolation Test1. Dig a hole in the proposed rain garden site (12”deep, 4-6” wide)2. Fill with water to saturate soil and then let standuntil all the water has drained into the soil3. Once water has drained, refill the empty holeagain with water so that the water level is about1” from the top of the hole4. Check depth of water with a ruler every hour forat least 4 hours5. Calculate how many inches of water drained perhour

DETERMINING THE DEPTHOF THE RAIN GARDENp. 24

DETERMINING THE DEPTHOF THE RAIN GARDEN Depth of rain garden is dependent upon the soil texture foundat the site of the rain garden Depth is usually 3-8 inchesp. 25

DETERMINING THE SIZEOF THE RAIN GARDENp. 25 The size of the rain garden is dependent upon the amount ofrunoff entering the rain gardenRain Garden Sizing TableBased on New Jersey’s Water Quality Design Storm (1.25” of rain over 2 hours)Size of 3” Deep Rain GardenCLAY SOIL*Size of 6” DeepRain GardenSILTY SOILSize of 8” DeepRain GardenSANDY SOIL500 ft2200 ft2100 ft275 ft2750 ft2350 ft2150 ft2112 ft21,000 ft2400 ft2200 ft2149 ft21,500 ft2600 ft2300 ft2224 ft22,000 ft2800 ft2400 ft2299 ft2Drainage Area*SOIL TEXTURE AMENDMENTS NEEDED

p. 26SOIL TEXTURE AMENDMENTS Soil texture amendments improve the rain garden’s infiltration rate.compostcoarse sandmulchriver rocks

p. 26SOIL QUALITY AMENDMENTS Soil quality amendments improve the raingarden’s growing conditions for plants Improve soil’s nutrient capacityREMEMBER:Your rain garden shouldNOT be permanently filledwith water – it should drainwithin 24 hours.

DETERMINING THEINLET AND OVERFLOW Stormwater runoff entersthe rain garden from aninlet Stormwater exits throughthe overflowp. 27

p. 27PREVENTING EROSION Slope no greater than 3:1 Slow down velocity of water flowing through raingarden– Add rocks to inlet area

DETERMINING MULCHQUANTITY Allow for a 3” depth mulch(triple-shredded hardwoodwith no dye) to be spreadthroughout the entire raingarden Every 100 square feet of raingarden needs 1 cubic yard(3” depth)p. 27

p. 29RAIN GARDEN DESIGNSHAPING YOUR RAIN GARDEN Use a garden hose or rope to outlinethe desired shape of your raingarden on the ground Many rain gardens are in the shapeof a circle or kidney bean, but yourrain garden can take on whatevershape you prefer

SELECTING PLANTS FORYOUR RAIN GARDEN The success of your rain garden depends onselecting the right plants for the right place Plant your rain garden with plants adapted foryour specific site Native plants can thrive without a lot of care,extra water, fertilizer, or pesticides Native plants are tolerant to dry and wetconditionsp. 29

DESIGN AESTHETICS Formal or traditionaldesign– Shrub bed– Perennial garden– Hedges Naturalized planting &design– Butterfly garden– Meadow (warm seasongrasses & wildflowers)– Buffer plantings

SITE CONSTRAINTS Sun vs. shadeExposure/windSoil characteristicsHydrologicconditions Road salts Vehicle/pedestriantraffic

PLANTS IN THE RIGHT PLACE Courtesy of Pinelands Nursery & Supply

p. 30PLANT SELECTIONSelect species based upon thefollowing qualities: Plant size Moisture tolerances Sun preferences Plant aggressiveness Salt tolerance Habitat creation

PLANT SELECTION Mature plant size– Proximity to buildingsand utility lines– Pruning and shaping Seasonal interest– Flowers– Fall color– Winter character Beneficial wildlife– Flowers for butterflies– Fruits for song birds

p. 30PLANTING DESIGN TIPS Plants that prefer wet conditions should be planted inthe deepest part (the base) of the rain garden Create depth in the rain garden by placing large and tallplants in the back, smaller plants in the front Plant masses of the same species together in oddnumbers Incorporate plants that have visual interest in the falland winter Native plants provide habitat to animals and requireless watering

PLANTING DESIGN: Mature Size of Plants

THE FUN PART!INSTALLING YOUR RAIN GARDEN

STEP ONE Delineate rain garden area Remove existing grass with a shovel or machinery

STEP TWO Excavate to design depth based on necessarystorage and soil amendment requirements

STEP THREE Add soil amendments, if necessary Combine amendments with existing soil using shovels or rototiller Loosen and prepare soil for grading and planting

STEP FOUR Prepare the berm, if necessary

STEP FIVE Prepare the overflow

STEP SIX Level the rain garden base

STEP SEVEN Plant native species

STEP EIGHT Apply mulch Allow for a 3” depth mulch (triple-shredded hardwood with no dye) to bespread throughout the entire rain garden For every 100 square feet of rain garden, you will need about 1 cubic yardof mulch (3” depth)

STEP NINE Water Plants

STEP TEN Appreciate a job well done

INSPECTION AND MAINTENANCEMAINTAINING YOUR RAIN GARDEN

MAINTENANCE MEASURESWEEKLY TASKS:ANNUAL ingMulchingPruningRe-plantingRemoving sedimentSoil TestingHarvesting PlantsCleaning of GuttersReplacing materials (stone,landscape fabric)

Completed Rain Gardens

Roof RunoffDesignInstalled Rain Garden

Parking Lot RunoffDesignInstalled Rain Garden

Roof, Sump Pump and DrivewayRunoffDesignInstalled Rain Garden

Roof RunoffDesignInstalled Rain Garden

Driveway RunoffDesignRain Garden Installed

Driveway RunoffDesignInstalled Rain Garden

Roof Runoff from Rain BarrelOverflowDesignInstalled Rain Garden

Roof RunoffDesignInstalled Rain Garden

Garage Roof Runoff andRain Barrel Overflow

Take Home Handouts

Handout GuidanceImpervious Surfaces: Rooftop(s) Driveway(s) Walkway(s) Deck(s) Patio(s) Shed(s)Drainage Area:

p. 22CHECK YOUR SOIL Infiltration/Percolation Test1. Dig a hole in the proposed rain garden site (12”deep, 4-6” wide)2. Fill with water to saturate soil and then let standuntil all the water has drained into the soil3. Once water has drained, refill the empty holeagain with water so that the water level is about1” from the top of the hole4. Check depth of water with a ruler every hour forat least 4 hours5. Calculate how many inches of water drained perhour

With sandy soils, the water should descend quickly. Withclay soils, the water should descend slowly.If the drainage rate is less than 1.5 inches per hour, or thewater does not drain within 24 hours, add soil textureamendments such as coarse sand during installation.Alternatively, consider placing the rain garden in a differentlocation on your property.It is important to note that sometimes an infiltration testprovides a false reading of a site’s soil conditions. Forexample, during dry conditions, an infiltration test maydemonstrate that the soil drains quickly and does not needamendments. However, during a rainy season, an infiltrationtest on that same soil may reveal that it is clayey and doesnot infiltrate well.

Thank you for attending!Sign up now for the Rain Garden Design WorkshoponTuesday, May 26thThis program sponsored by Hamilton Township through its ongoingpartnership with theRutgers Cooperative Extension Water Resources Program.For more information contact:Jeremiah BergstromChris tgers.edu

RAIN GARDEN TECHNICAL ASSISTANCE PROGRAM . RAIN GARDEN EDUCATION WORKSHOP . HAMILTON TOWNSHIP . MERCER COUNTY . dripline of trees 7. Provide adequate space for rain garden p. 17 . . landscape fabric) Completed Rain Gardens . Roof Runoff . Design . Installed Rain Garden . Parking Lot Runoff .