Rain Garden Site Selection and Installation - Rutgers Cooperative ...

Frederick CountyRain Garden• A rain garden was constructed at Hedgebrook Farm in 2008• GOAL: To have the rain garden serve as a demonstration for county residentswho are interested in controlling polluted runoff and to help recharge thegroundwater

What is a RainGarden?• Shallow landscapeddepression that treatsstormwater runoff.• Designed to merge twoimportant goals: aestheticsand water quality• Can be blended into thelandscape and made to looknatural.• Water is directed into themby pipes, swales, or curbopenings.

Benefits• Designed to intercept, treat,and infiltrate stormwater atthe source before itbecomes runoff• Provides very high pollutantremoval efficiencies• Can be incorporated intothe landscapes of manylocations

The Parts of aRain Garden

• Infiltration of runoff− Provides flood control, groundwater recharge, and nutrient removalThe Science BehindRain Gardens• Absorption to soil particles− Removes dissolved metals and soluble phosphorus• Plant uptake− Removes small amounts of nutrients• Microbial processes− Removes organics and pathogens• Exposure to sunlight and dryness− Removes pathogensNOTE: 90% of all storm eventsproduce less than 1 inch of rain.Therefore, the key to reducingpollutant loads is to treat therunoff associated with the first 1inch of rain (Clayton & Schueler,1996).• Sedimentation and filtration− Removes total suspended solids, floating debris, trash, soil-boundphosphorus, some soil-bound pathogens

Infiltration of RunoffHow much water does a typical rain garden treat in a year?• 90% of rainfall events are less than 1.25”• New Jersey has approx. 44” of rain per year• The rain garden will treat and recharge:0.9 x 44” = 40”/year = 3.3 ft/year• The rain garden receives runoff from 1,000 sq.ft.• Total volume treated and recharged by the rain garden is1,000 sq. ft. x 3.3 ft/year = 3,300 cubic feet/year,which is 25,000 gallons/year• Build 40 rain gardens and we have treated andrecharged 1 million gallons of water per year!

How To Install aRain Garden

Steps3. Maintenance2. Installation1. PlanningMendham Township Elementary School, Morris County

Planning Steps• Identify Site• Site Visit1. Planning• Design Calculations

Rain GardenPlacement• The rain garden should be at least 10 feet from the house soinfiltrating water doesn’t seep into the foundation.• Do not place the rain garden directly over a septic system.• Do not put rain garden in places where the water already ponds orthe lawn is always soggy.• Place in full or partial sunlight as a first option• Select a flat part of the yard for easier digging as a first option.• Avoid large tree roots.Things to Rememberhttp://clean-water.uwex.edu/pubs/raingarden/rgmanual.pdf

Determine Existing Utility Lineshttp://www.missutilityofvirginia.com/

Planning StepsIdentify SiteIdentify the Drainage AreaBeforeParking Lot/DrivewayRoofUnion County Vocational SchoolHockman Farm, Winchester, Virginia

AfterParking Lot/DrivewayRoofUnion County Vocational SchoolHockman Farm, Winchester, Virginia

Parking Lot/ Driveway with a Curb CutBeforeAfterRutgers Cooperative Extension of Monmouth County, Freehold, NJ

Planning StepsSite VisitDetermine Current Stormwater FlowFlowIf the area is prone toflooding, it may bedifficult to improve thedrainage.Union County Vocational School

Planning StepsIdentify SiteIdentify Drainage ProblemsProperty FloodingUnion County Vocational School

Planning StepsIdentify SiteCurrent Landscaping PracticesUnion County Vocational School

Planning StepsSite VisitMeasure Drainage AreaRoofSurface Area = (L1xW) + (L2xW)Roof= (15’x20’) + (10’x20’)= (300’) + (200’)= 500 square feetWL1L2Hockman Farm, Winchester, Virginia

Make observationsduring storms toestimate thedrainage areaRain GardenOr use surveyequipmentDrainage Area

Planning StepsSite VisitMeasure Drainage AreaRain Garden Sizing Tablefor New Jersey’s Water Quality Design StormSurface Area of ImperviousSurface to be Treated(sq. ft.) or (LxW)Size of 6” deep RainGarden(sq. ft.) or (LxW)500 sq. ft. 100 sq. ft. or 10’x10’750 sq. ft. 150 sq. ft. or 15’x10’1,000 sq. ft. 200 sq. ft. or 20’x10’1,500 sq. ft. 300 sq. ft. or 30’x10’2,000 sq. ft. 400 sq. ft. or 20’x20’

Planning StepsSite VisitDetermine SlopeSlope =H1 – H2x 100 =9” – 3”=0.75’ – 0.25’x 100 = 5% slopeL10’ 10’

Determine SlopePlanning StepsSite VisitThe depth of your rain garden depends upon the slope of your lawn.SlopeRain Garden Depth< 4% 3” – 5”5% – 7% 6” – 7”8% – 12% 8”> 12% Consider Another Location

Percolation TestSteps:Planning StepsSite Visit1. Dig a hole 12 inches deep by 6 inches in diameter.2. Fill hole with water and let stand until all the waterhas drained into the ground.3. Refill the empty hole with water again. Measure thedepth of water with a ruler.4. Check the depth of water with a ruler every hour for4 hours.5. Calculate how many inches of water drained perhour.~1 inch of water draining per hour is good

Percolation TestPlanning StepsSite Visit12 34 st nd rd th HourRulerWater should be completelydrained within 24 hours.

Planning StepsSite VisitSoil Test• Sample the soil and send to the Rutgers SoilTesting Lab for:• Nutrient analysis/ recommendations• pH analysis/ recommendations• Percent sand/ silt/ clay• Soil Texture TestRoll soil into a ball in hand and see how it forms• Hard ball – Clay/Silt soil• Soft ball – Loamy soil• No ball – Sandy soilGloucester County 4-H FairgroundsBut, don’t worry – clay/silt andsandy soils can be amended to getthe preferred loamy soil texture

Take PhotographsPlanning StepsSite VisitBurlington County Community Agricultural Center

Planning StepsDesign CalculationsGeneral Soil Amendments Amounts for a 100 sq ft RainGarden that is 6 Inches DeepSoil AmendmentSandCompostFertilizerLimeAmount for 100 sq ft Rain Garden1 cubic yard1 cubic yardFollow Soil Test ResultRecommendationsFollow Soil Test ResultRecommendationsGloucester County 4-H Fairgrounds

Planning StepsDesign CalculationsApproximate Amount of Plants Based on Future Mature SizeSize of RainGardenApproximate Amountof Plants100 square feet 1 Small Tree (Optional)7 Shrubs24 Herbaceous Species200 square feet 1 Small Tree (Optional)14 Shrubs48 Herbaceous SpeciesLeonard Park, Morris County

Types of PlantsPlanning StepsDesign Calculationshttp://plants.usda.govFacultative Wetland (FACW)Facultative Upland (FACU)Lowest Zone/Ponding AreaHighest Zone/Upland AreaMiddle Zone/Depression AreaFacultative Wetland (FACW),Facultative (FAC),Facultative Upland (FACU)

Planning StepsDesign CalculationsAmount of Mulch Required fora Three Inch Thick LayerSize of RainGardenApproximate Amountof Mulch25 square feet 0.25 cubic yard50 square feet 0.50 cubic yard100 square feet 1.0 cubic yard200 square feet 2.0 cubic yardsTriple-shredded Hardwood with No DyeSpringfield Municipal Annex Building, Union County

Optional SuppliesPlanning StepsDesign CalculationsSupplies may include:• River rock• PVC pipe• Deer fencingPVC PipeRiver RockSoakerHoseSpringfield Municipal Annex Building, Union County

Installation Steps• Remove existing grass• Excavate to the desired elevation and grade• Add soil amendments• Prepare the berm2. Installation• Prepare the overflow• Level the lowest zone/ponding area• Plant the native plants• Apply the mulch• Water the native plants

Remove Existing GrassInstallation StepsGloucester County 4-H Fairgrounds

Installation StepsExcavate to the Desired Elevation and GradeLeonard Park, Morris CountyGloucester County 4-H Fairgrounds

Installation StepsAdd Soil AmendmentsGloucester County 4-H Fairgrounds

Installation StepsPrepare the BermLeonard Park, Morris County

Installation StepsPrepare the OverflowOverflowGloucester County 4-H FairgroundsLeonard Park, Morris County

Installation StepsLevel the Lowest Zone/ Ponding AreaWheaton Arts and Cultural Center, Cumberland County

Installation StepsPlant the Native PlantsCut the Root BallUlster County, New York

Installation StepsPlant the Native PlantsPlanting HoleSame Depthas Root BallUlster County, New YorkHockman Farm, Winchester, Virginia

Installation StepsApply the MulchProtect Small Plantswhen MulchingUlster County,New York

Water the Native PlantsInstallation StepsHockman Farm, Winchester, Virginia

Maintenance Steps3. MaintenanceShort-Term MaintenanceLong-Term MaintenanceMadeline will discuss this later…

FAQsFrequently Asked Questions• Will my rain garden cause a mosquito problem?• Will my rain garden cause flooding?• What about deer?• How do I slow down the speed of water as it enters the garden?

FAQsWill my rain garden cause a mosquito problem?• There shouldn’t be a mosquito problem if the garden isproperly sited and designed. Rain gardens shoulddrain in less than two days.• Mosquitoes have a 10 day life cycle from egg to adult.• Mosquitoes that carry most diseases do not live inponds. They prefer small amounts of standing watersuch as holes in trees, old tires or bird baths.

FAQsWill my rain garden cause flooding?If your rain garden does not drain out the water after ~24 hours, itis time to re-evaluate your rain garden. Maybe try:• Building berms and/or adding plants• Adding COARSE sand (not sandbox sand) with organic mulchto the rain garden to help infiltrate the water

FAQsWhat about deer?Try fencing, deer resistant plants, or deer retardant sprays.New Jersey Highlands Council Building, Morris County

FAQsHow do I slow down the speed of water as it enters thegarden?Try one or more of the following:(1) Attach a perforated plastic diffuser tothe end of your gutter/ downspout(2) Use river rock at the entrance point ofthe rain garden(3) Site your rain garden within a 10 – 15foot grass buffer between the gardenand the gutter/downspout. Use nativegrasses and let them grow tall.Essex County Environmental Center

The Bottom Line• Rain gardens are designed to intercept, treat, and infiltratestormwater at the source, before it becomes runoff.• The plants are native to the region and help retaincontaminants that could otherwise harm nearby waterways.• Rain gardens are beautiful, inexpensive and lowmaintenancegardens that you can easily install at home.Linda HenryLinda HenryWoodbridge Board of Health, Middlesex County

Future Site ofRain GardensFrederick Douglas Park, Winchester, Virginia

Any Questions?Essex County Environmental Center, Essex Countyhttp://water.rutgers.edu