Rutgers Cooperative Extension Infrastructure Water .

Rutgers Cooperative ExtensionWater Resources ProgramChristopher C. Obropta, Ph.D., P.E.Extension Specialist in Water ResourcesRutgers, The State University of New tgers.eduJeremiah Bergstrom, LLA, ASLASenior Research Project ManagerRutgers, The State University of New duThis document has been prepared by the Rutgers Cooperative ExtensionWater Resources Program with funding provided by Surdna Foundation,the National Fish and Wildlife Foundation, and the New Jersey AgriculturalExperiment Station. This work is intended to provide guidance for thedesign and implementation of green infrastructure practices throughoutNew Jersey.Cooperating Agencies: Rutgers, The State University of New Jersey, U.S. Department of Agriculture, and County Boards ofChosen Freeholders. Rutgers Cooperative Extension, a unit of the Rutgers New Jersey Agricultural Experiment Station, is anequal opportunity program provider and employer.for reducing the impacts ofimpervious cover on water quality

greeninfrastructurefor new jerseyAs the amount of impervious surfaces like roadways, parking lots, androoftops increase, stormwater runoff increases. Scientific research haslinked these increases in impervious surfaces to degraded waterways.Because of this, many municipalities have limits on impervious cover forindividual building lots. Green infrastructure can be designed to mitigateDRAINAGE PIPEthese increases in impervious cover by reducing their impact on localDrainage pipes shouldhave a 4-inch minimumdiameter and a 20-footlength. Slopes shouldalso be 1.5 inches per10 feet to prevent backflooding.waterways.New Jersey has675,200SLOTTEDGRATEThis prevents debris from enteringthe system.acres of imperviouscoverCounty BoundariesImpervious Surface (%)by Municipality1-55-10LANDSCAPEFABRICFabrics are used toprevent silt fromentering the system.SMALL CATCHBASINAny debris thatsurpasses the grateis collected here.10-3030-50SUMP LINERHOLES 50This brochure is intended to serve as a quick reference guide for greenAGGREGATEinfrastructure. Many of these practices can easily be installed on sites toA layer of 3-4 inchclean crushed rockis used for filtrationand for extraprotection.offset increases in impervious surfaces.2Liner holes helprunoff infiltrate ata steady rate toprevent flooding.19

DRY WELL SYSTEMSGreen infrastructure is an approach to stormwater management thatSTORAGE AND INFILTRATIONis cost-effective, sustainable, and environmentally friendly. GreenA dry well is an underground structure built to manage surfaceinfrastructure practices capture, filter, absorb, and/or reuse stormwaterrunoff that cannot directly infiltrate into the ground. The systemaccepts stormwater runoff through a pipe and captures it in a largecontainer. The system receives water from an entry pipe or channeland discharges the water through small openings distributed alongthe sides and bottom of the container. The system is designedto accept a large quantity of stormwater during a rainfall event.Subsequent to the storm, the dry well allows the stormwater toslowly infiltrate back into the ground.Dry wells can be designed in a number of ways. Simple dry wellsare a pit filled with gravel, riprap, and rubble. Other dry wells aredesigned as a large perforated concrete container. These dry wellsare usually buried completely and provide storage for a largerstormwater capacity.to help restore the natural water cycle. When used as components of astormwater management system, green infrastructure practices such asbioretention, green roofs, pervious pavement, rain gardens, and vegetatedswales can produce a variety of environmental benefits. In addition toeffectively retaining and infiltrating runoff, these practices can help filterair pollutants, reduce energy demands, mitigate urban heat islands, andsequester carbon while also providing communities with aesthetic andnatural resource benefits.When managing stormwater with green infrastructure practices, theoverall goal is to disconnect impervious surfaces that are connected (i.e.,drain directly to sewer systems or local waterways). Green infrastructurepractices can be designed to capture and infiltrate stormwater. Thesepractices tend to filter water using soil, as in the case of bioretention, orusing stone, as in the case of porous asphalt. In areas where infiltrationis not possible, these green infrastructure practices can be used as adetention system to store runoff and slowly release it after the storm event.Some green infrastructure practices are used to harvest stormwater runofffor non-potable water usage such as watering gardens. Other greeninfrastructure practices, like bioswales, are designed to move water fromLOCATION: Holmdel, NJ.This residential dry well wasinstalled in Monmouth County.It is a underground systemthat uses an empty containerto store large quantities ofstormwater during rainfallevents.one location to another while filtering pollutants.The following pages describe some green infrastructure practices thathave been proven to be successful in New Jersey. These practices include:bioretention/rain gardens, bioswales, downspout planters, stormwaterplanters, cisterns and rain barrels, permeable pavements, tree filter boxes,and dry well systems.18photo tml3

BIORETENTION/RAIN GARDEN SYSTEMSINFILTRATION AND STORAGEA rain garden, or bioretention system, is a landscaped, shallowdepression that captures, filters, and infiltrates stormwater runoff.The rain garden removes nonpoint source pollutants from stormwaterrunoff while recharging groundwater. A rain garden serves as afunctional system to capture, filter, and infiltrate stormwater runoffat the source while being aesthetically pleasing. Rain gardens arean important tool for communities and neighborhoods to creatediverse, attractive landscapes while protecting the health of thenatural environment. Rain gardens can also be installed in areasthat do not infiltrate by incorporating an underdrain system.Rain gardens can be implemented throughout communities to beginPERVIOUSCONCRETEPervious concrete isinstalled to act as anadditional storagesystem to increasethe stormwatercapacity treated bythe system.the process of re-establishing the natural function of the land. Raingardens offer one of the quickest and easiest methods to reducerunoff and help protect our water resources. Beyond the aestheticand ecological benefits, rain gardens encourage environmentalstewardship and community pride.ASPHALTLOCATION: Hamilton, NJThis residential rain garden is 150 square feet andsix (6) inches deep. It wasdesigned to capture therainwater from the roof ofthis home.4UNDERDRAINSystems with lowinfiltration rates due tosoil composition areoften designed with anunderdrain system todischarge the water.This system isoften designed withconventional asphaltin areas of hightraffic to preventany damage to thesystem.17

TREE FILTER BOXESNATIVE PLANTSSTORAGE AND INFILTRATIONA rain garden is plantedwith a variety of grasses,wildflowers, and woodyplants that are adaptedto the soil, precipitation,climate, and other siteconditionsTree filter boxes can be pre-manufactured concrete boxes orenhanced tree pits that contain a special soil mix and are plantedwith a tree or shrub. They filter stormwater runoff but providelittle storage capacity. They are typically designed to quickly filterDRAINAGE AREAThis is the area ofimpervious surface thatdrains stormwater runoffto the rain garden.stormwater and then discharge it to the local storm sewer system.BERMLOCATION: Parsippany, NJThis enhanced tree pit is located at the Parsippany-TroyHills Municipal Court parkinglot. The tree pit collects andfilters water from the existingparking lot.The berm isconstructed as abarrier to control,slow down, andcontain stormwater.Often tree filter boxes are incorporated into streetscape systemsPONDING AREAseveral boxes (as shown on the next page). This is also coupledThe ponding area is thelowest, deepest visiblearea of the garden.When designed correctly,this area should drainwithin 24 hours.with pervious concrete to increase the storage capacity for rainwaterin the system.16CURB CUTthat include an underlying stormwater system which connectsINLETThis curb cut andconcrete flow pad aredesigned to help redirectstormwater runoff to therain garden system andout of the storm drain.This is the area wherestormwater enters. Theinlet is often lined withstone to slow water flowand prevent erosion.5

BIOSWALESDRAINAGE AREACONVEYANCE AND INFILTRATIONThe drainage area of theporous asphalt system isthe conventional asphaltcartway and the porousasphalt in the parkingspaces. Runoff from theconventionalasphaltflows into the porousasphalt parking spaces.Bioswales are landscape features that convey stormwater from onePOROUS ASPHALTlocation to another while removing pollutants and allowing water toIt is common to designporous asphalt in theparking stalls of a parkinglot. This saves moneyand reduces wear.infiltrate. Bioswales are often designed for larger scale sites wherewater needs time to move and slowly infiltrate into the groundwater.Much like rain garden systems, bioswales can also be designedwith an underdrain pipe that allows excess water to discharge to thenearest catch basin or existing stormwater system.UNDERDRAINLOCATION: Parsippany, NJThis bioswale was installedat St. Gregory’s Church.The bioswale was designedto capture water from theparking lot and move ittoward the forest area on thesouth end of the site.Systems with lowinfiltration rates due tosoil composition areoften designed with anunderdrain system todischarge the water.ASPHALTThis system is oftendesigned with conventionalasphalt in areas of hightraffic to prevent anydamage to the system.SUBGRADEPorous pavements areunique because of theirsubgrade structure. Thisstructure includes alayer of choker course,filter course, and soil.615

PERMEABLE PAVEMENTSSTORAGE AND INFILTRATIONThese surfaces include pervious concrete, porous asphalt,interlocking concrete pavers, and grid pavers. Pervious concreteNATIVE PLANTSand porous asphalt are the most common of the permeable surfaces.A bioswale is plantedwith a variety of grasses,wildflowers, and woodyplants that are adaptedto the soil, precipitation,climate, and other siteconditions. The vegetationhelps filter stormwaterrunoff as it moves throughthe system.They are similar to regular concrete and asphalt but without the finematerials. This allows water to quickly pass through the materialinto an underlying layered system of stone that holds the water,allowing it to infiltrate into the underlying uncompacted soil. Theyhave an underlying stone layer to store stormwater runoff and allowit to slowly seep into the ground.CONVEYANCEUnlike other systems,the bioswale is designedto move water through avegetative channel as itslowly infiltrates into theground.By installing an underdrain system, these systems can be used inareas where infiltration is limited. The permeable pavement systemwill still filter pollutants and provide storage but will not infiltrate therunoff.TYPICAL POROUS ASPHALT SUBGRADE: CROSS-SECTIONPOROUS ASPHALTCHOKER COURSEFILTER COURSEEXISTING SOILEXISTING BEDROCK14SLOPEThe slope is designed ata maximum of 3:1. Theseslopes often requireerosion control materialsfor stabilization.INLETThis is the area wherestormwater enters. Theinlet is often lined withstone to slow water flowand prevent erosion.7