26LID Manual Book Sample

7/25/2019 26LID Manual Book Sample

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Environmental planning typically enjoys success in natural settings, butthe real challenge for developing sustainable cities is ensuring ecosystemintegrity within urban contexts. Naturally-determined ecosystems have beenirrevocably altered by human activity. Indeed, the greatest ongoing problemin planning involves designing within human-dominated ecosystems.

After all, 80% of the US population now lives in urban areas. Low ImpactDevelopment: A Design Manual for Urban Areas introduces generalaudiences to designing landscapes for urban stormwater runoffa primarysource of watershed pollution. This manual can be reviewed episodically,much like a lifestyle publication, or read in its entirety for a comprehensiveunderstanding. The goal is to motivate awareness and implementationof LID in a wide cross-section of stakeholders, from property owners tomunicipal governments that regulate infrastructure development. Thoughnot exhaustive in its coverage of LID techniques (i.e., you will not be ableto engineer a LID project from this manual), this manual does providea holistic framework in which a novice homeowner and an experienceddeveloper can each find an equally transformative role to enact.

LID Low ImpactDevelopmentHow to Use This Manual

If you live in the blue, this manual is for you!

a design manualfor urban areas

LowImpactDeve

lopment:adesignmanualforurbanareas

UACDC

Arkansas

2010 UACDC, Fayetteville, Arkansas http://uacdc.uark.edu

FAY JONES SCHOOL OF ARCHITECTURE

UNIVERSITY OF ARKANSAS PRESS

A COLLABORATION

FAYETTEVILLE 2010

:

ISBN-13: 978-0-9799706-1-0

9 780979 970610

:


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ContentsIntroduction

How can we implement LID? Building Property Street Open Space

What are the LID facilities?

What can you do?

Where can you learn more?

2

44465890

124

142

188

212

LIDLow ImpactDevelopmenta design manualfor urban areas

University of Arkansas Community Design Center

FAY JONES SCHOOL OF ARCHITECTUREUNIVERSITY OF ARKANSAS PRESS

A COLLABORATION

FAYETTEVILLE 2010


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impervious surfaces

What if urbanstormwater

infrastructure

enhancedecologicalfunctioningto serve as

a civic asset

rather than anenvironmentalliability?

...in many cases the first flush ofstormwater in an urban area mayhave a level of contamination

much higher than normallypresent in sewage...

Craig Campbell and Michael Ogden,Constructed Wetlands in the Sustainable Landscape

2 3


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Lawns use more equipment,labor, fuel, and agriculturaltoxins than industrial farming,making lawns the largestagricultural sector in the

United States.

Richard Burdick, The Biology of Lawns,Discover, July 2003

industrial landscapes

4 5


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urban stream syndrome

By replacing the stream thatwas once here, the bare andsterile concrete replaces

the fecundity of soil andplants. The concrete has justone purpose, ignoring themultiplicity of other purposesserved by the landscape it

replaced...

John Tillman Lyle, Landscape: Source of Life or Liability,Reshaping the Built Environment

6 7


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Research indicates that whenimpervious area in a watershedreaches 10 percent, stream

ecosystems begin to showevidence of degradation,and coverage more than 30percent is associated withsevere, practically irreversible

degradation.

Metro Portland,Green Streets:Innovative Solutions for Stormwater and Stream Crossings

urban sprawl

8 9


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death by a

thousand cuts

stream scouringwater contaminationflash flooding

10 11


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work more like softengineering.offering the 17 ecosystem services

1. atmospheric regulation2. climate regulation 3. disturbance regulation 4. water regulation 5. water supply 6. erosion control and sediment retention 7. soil formation8. nutrient cycling 9. waste treatment 10. pollination 11. species control 12. refugia/habitat 13. food production14. raw material production 15. genetic resources 16. recreation 17. cultural enrichment

12 13

What Low Impact

Development (LID)does is make hardengineering...


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Some believe that ecologically-based stormwater managementis unattainable in dense urban

areas, but consider the following...

this is a population of 8,000 this is a population of 4,000,000

hard engineering soft engineering

14 15


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N2

P

N

N

P

P

P

P

P

N N

O2

Phytoremediationis the mitigation ofcontaminated soil,water, or air usingplants to contain,degrade, or eliminatepollutants.

A catch basin ispart of a stormwatermanagement system

designed to trapdebris and sediment

before it enters a pipenetwork.

NO3-

absorbed asnutrients

N

O2

NO3

-

PO4-3

NH4+

pollutedrunoff

biomassabsorption

NO3-

PO4

-3

NO3

-

PO4-3NO

3-

PO4-3

NO3-

PO4

-3

NH4+

pollutantsbacteria

petroleum-based productssediment

heavy metalfertilizer

using plants to remove

pollutants from soils,sediment, or waterinto harvestable plantbiomass

process where plantsuptake contaminantsand release them intothe atmosphere asthey transpire

sequestration ofcontaminants in the soilthrough absorption oraccumulation around theroot zone

metabolic processthat breaks downor degradescontaminants intosimpler moleculesor elements

phytoextraction

phytovolatilization

phytostabilization

phytodegradation

rootstor

age

uptake

biochemicalbreakdown

polluted runoffpolluted runoff

output

PO4

-3

PO4-3

NH4

+

mechanical

b

iological

hard engineering soft engineering

input

16 17


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infiltration

filtration

treatment

conventional management: pipe-and-pond infrastructuredrain, direct, dispatch

low impact management: watershed approachslow, spread, soak

flood

plain

uplandcommunity

uplandcommunity

riparianedgeriparianedge

streamchanneldetentioncatch basins

discharge

pipes

hard engineering soft engineering ...metabolizes pollutants

on siteparks, not pipes!...just transfers pollution

to another site

18 19


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filtration:The sequestrationof sediment from stormwaterrunoff through a porous mediasuch as sand, a fibrous rootsystem, or a man-made filter.

retention:The storage ofstormwater runoff on site toallow for sedimentation ofsuspended solids.

detention:The temporarystorage of stormwater runoffin underground vaults, ponds,or depressed areas to allow formetered discharge that reducepeak flow rates.

ow control:The regulation oformwater runoff flow rates.

infiltration: The verticalmovement of stormwaterrunoff through soil, recharginggroundwater.

treatment: Processes thatutilize phytoremediation orbacterial colonies to metabolizecontaminants in stormwaterrunoff.

low spread soak

integrating hard engineering ...and soft engineeringtoward a LID approach

mechanical biological

flow control detention retention filtration infiltration treatment

20 21


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plants

water

soils

What is LID?Low Impact Development (LID) is anecologically-based stormwatermanagement

approach favoring soft engineering to managerainfall on site through a vegetated treatmentnetwork. The goal of LID is to sustain asites pre-development hydrologic regime byusing techniques that infiltrate, filter, store,and evaporate stormwater runoff close toits source. Contrary to conventional pipe-and-pond conveyance infrastructure thatchannels runoff elsewhere through pipes,catchment basins, and curbs and gutters,LID remediates polluted runoff through a

network of distributed treatment landscapes.

filtration

evapotranspiration

infiltration

media and processes of LID

Stormwater infrastructure canbe planned to deliver valuableecological benefits to botanize

the city...2322


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runoffvolume

time

afterurbanization

beforeurbanization

26 27

to flood damage, property loss from erosion, heat islandeffect, pollution, and need for irrigation have promptedgreater regulatory oversight over nonpoint source pollutionand a call for green development solutions. Infrastructurecan be designed to provide greater ecological and urbanservices at lower costs. With LID, streets no longer haveto be ecological liabilities, and stream and lake ecologicalfunctioning are enhanced.

Water and land should be developed in harmony. NewLID practices based on ecological soft-engineering canmitigate the deleterious impacts of urbanization on theenvironment, particularly in the substitution of naturalground cover or porous media for impervious surfaces.

Shockingly, the rate of increase in impervioussurfaces has exceeded the rate of populationgrowth by 500 percent over the last 40 years.

From Individual Facilities to Networks: BMP to LIDBest Management Practice (BMP) has been commonlyused in conventional hard-engineering to identify lot-based management facilities such as a detention pond.However, BMPs are focused more on engineering ratherthan planning. In recognizing the need to comprehensivelyaddress stormwater runoff, the USEPA has recentlyredefined the term as a practice or combination ofpractices that are an effective, practicable means ofpreventing or reducing the amount of pollution generatedby nonpoint sources. BMPs now address stormwaterrunoff quantity and quality by employing both mechanicaland biological processes.

From the lot to the neighborhood, city, and region, BMPs,

or LID facilities, are connected in a distributed networkto reduce and treat urban stormwater runoff before itenters receiving waterbodies. LID facilities are combinedwith smart growth practices, such as compact, walkableneighborhoods and open space preservation (see www.epa.gov/smartgrowth), resulting in LID. Successful LIDrequires participation from property owners, developers,cities, and regulatory agencies in a comprehensiveplanning process. Everyone has an important role to play.

of the nations watersheds exhibit good water quality.Besides discharges from agricultural land uses and siteconstruction, much of this can be attributed to nonpointsource pollution from urban stormwater runoff channeledby impervious surfacesroofs, sidewalks, parking lots,

and roadsduring the first flush of a storm event.

Indeed the first hour of urban stormwater runoffhas a pollution index much higher than that of raw

sewage.

Stormwater runoff in our auto-dominated communitiesis toxic because it concentrates hydrocarbon residuesfrom household and lawn care chemicals, oil, gasoline,

brake fluid, asphaltic products in roads and roofs, andheavy metals, which are ultimately deposited into ourwatersheds. Conventional hard-engineered stormwatermanagementneither aware nor responsive to runoffsharmful consequencesemploys pipe-and-pondmethods to drain, direct, and dispatch untreated runofffrom a site. As with most conventional waste managementinfrastructure, pipe-and-pond systems simply transfer

pollution problems from one place to another.

Besides reduced water quality, stormwater runoff has ledto another major pollution problem, widespread streamimpairment commonly known as urban stream syndrome.Urban stream syndrome describes unhealthy stream flowregimes marked by chronic flash flooding, altered streammorphologies, elevated nutrient and contaminant levels,excessive sedimentation, loss of species diversity, and

higher water temperatures.

This imbalance in stream metabolism impairs ecological

functioning and disrupts the 17 ecological services that ahealthy stream delivers (see list p.13). These life-affirmingservices constitute four basic categories; provisioningservices that supply food, water, and energy; regulatingservices that purify water, air, and control disease;supporting services, which promote nutrient cyclingand reproduction; and cultural services for intellectual,recreational, and spiritual well being. Escalating costsassociated with the loss of these ecological services due

stormwater discharge beforeand after urbanization


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How can weimplement LID?

LID concepts are scalable to various sized projects andland-use types. Dividing urban development into itsconstituent componentsbuilding, property, street andopen spaceillustrates stakeholder action opportunities

within each component. The goal is not just to minimizeimpact, but to develop regenerative and productive urbanlandscapes that continually renew ecosystem functioning.

buildingpp. 46-57

design thebuilding as anet energyproducer thatrechargesgroundwater

and harvestsrainwater

propertypp. 58-89

substitutean ecologi-cally-basedstormwatertreatmentsystem for

an otherwisedecorativelandscape

streetpp. 90-123

design thestreet as agarden toachieve trafficcalming andstormwater

management

open spacepp. 124-141

comprehen-sively planopen spaceas a greennetworkthat delivers

vital ecologi-cal services atthe scale of awatershed


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infiltration

retention

storage

filtration

infiltration

evapotranspiration

biodiversity

treatment

How can we

transform the

roof?

How can we

transform the

walls?

How can we

transform the

ground?

buildingLIDOverviewBuildings present ready opportunities for harvestingstormwater runoff from roofs through small-scale embeddedtechnologies. LID facilities are one aspect of smart buildingdevelopment that optimize feedback between environmentand building to achieve net energy production, or regenerativedevelopment (versus sustainable development, which is carbonneutral). LID facilities are chosen according to the level ofecological service desired. The simplest service is groundwaterrecharge from roof stormwater runoff. Gutters and leadersthat channel rainwater create concentrated discharges andare avoided in favor of devices that slow, spread, and soakrainwater throughout the site. A higher level of service involvesvegetated or green roofs, which absorb and evaporaterainwater through a cultivated plant and soil community. Greenroofs are superior building insulators, minimizing heating andcooling demands. Green walls minimize solar gain during the

summer and wind loading during the winter.

Rainwater harvesting offers three basic levels of service,involving storage cisterns with options for treatment. Thesimplest service is rainwater reuse for outdoor landscapeirrigation. A more complex harvesting service incorporates agreywater building supply with additional treatment for non-potable water uses like toilet flushing and landscape irrigation.

The highest level of service involves harvesting for potable(drinking) water which requires UV light disinfection for aprivate water system, and when combined with water from a

public utility includes proper back-flow prevention.

Placement of LID facilities on a building site should becarefully considered. Infiltration and treatment facilities canbe used next to a building to capture roof runoff. Infiltrationfacilities, however, should be located at least 10 feet awayfrom buildings, as they may cause the shrinking and swelling

of soils, which can negatively affect foundations.


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...one inchof rainfall on a 1,000 square-foot roof yields about 623 gallons of water

safe harvesting potentia

building

alerton harvesting rainwaterWhen considering rainwaterharvesting, keep in mind thatpetroleum-based roofing andtreated wood products leachtoxins. Studies have shownthat these products are knownto cause cancer and mentaldefects. Harvested rainwaterfrom these surfaces shouldonly be used for ornamentallandscape irrigation.

Harvesting rainwater fromthese surfaces is safe for useon edible landscapes becausethey do not pose contaminationrisks, but will require filtrationand disinfection for potable(drinking) water uses.

Roof Materials

clay tile roofStormwater runoff from a claytile roof may produce minorsediment. Clay tiles can offerhigh albedo surfaces for heatisland mitigation. Clay rooftiles have excellent harvestingpotential. Harvesting Potential: High Heat Island Mitigation: Moderate Initial Cost: Medium Durability: 50-75 years

metal roofStormwater runoff from a metalroof has very low pollutantlevels. Metal roofs haveexcellent harvesting potential. Harvesting Potential: High Heat Island Mitigation: High Initial Cost: Medium to High Durability: 40-60+ years

wood shingleLeaching from treated woodproducts may contain toxinsand carcinogens. Make everyeffort to use products madefrom cedar since it is typicallyuntreated and thus a safeharvesting alternative. Harvesting Potential: Moderate Heat Island Mitigation: Moderate Initial Cost: Medium Durability: 10-20 years

vegetated roofAlso known as a green roof,they can treat and retain 60-100% of the stormwater theyreceive. Other benefits includeimproved air quality, heatisland mitigation, and urbanbiodiversity. (see VegetatedRoof pp. 170-171) Harvesting Potential: High Heat Island Mitigation: High Initial Cost: High Durability: 40+ years

membrane roof systemMembrane roofs, like EPDM,modified bitumen, and tarand gravel, are petroleum-based and have high levels ofpollutants; treatment is neededat the wall and/or ground. Ifharvesting is desired do not useto irrigate edible landscapes orfor potable needs. Harvesting Potential: Low Heat Island Mitigation: Low Initial Cost: Low-Medium Durability: 10-30 years

sphalt/fiberglass shingletormwater runoff from theseofs have high levels of

ollution; treatment is neededthe wall and/or ground. If

arvesting is desired do not use irrigate edible landscapes orr potable needs.Harvesting Potential: LowHeat Island Mitigation: LowInitial Cost: LowDurability: 15-20 years


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canopy interceptionand evaporation

infiltration

filtrationrunoff

transpiration

climateregulation

habitat

Due to compactionand poor planning the average lifespan of an urban tree is 13 years.

throughfalllitter interceptionand evaporation

Designing forUrban Trees

Streets should be designed to accommodatetree root growththe most critical factor in

implementing tree lined streets.

Healthy trees are essential components of greeninfrastructure and urban forestry. Shade trees plantedalong hard surfaces reduce the heat island effect andimprove air quality. Besides functioning as carbon sinks,trees also reduce stormwater runoff through interception,evapotranspiration, throughfall, and flow attenuation.Trees help create a sense of place, reduce noise andglare, and provide a safety barrier for pedestrians fromtraffic, which is why neighborhood value is increased by

their presence.

Trees vary in their growth requirements and rates basedon the biological and physical conditions of the site. Treesshould be chosen based on cold hardiness, mature sizeand shape, drought tolerance, rooting characteristics, andresistance to insect and disease problems. For a list ofsuitable urban trees, consult a local nursery or landscapedesign professional (also see Urban Trees for Zones

4-8 pp. 100-101).

The planting area should accommodate the anticipated

root structure at maturity, ensuring absorption of waterand nutrients. Remember that roots can extend wellbeyond the canopy of the tree. Spacing between treesshould reflect species crown size at maturity. With properplanning and care, street trees can live well beyond their

average 13-year lifespan.

underdrain

no compact ion zone

utilities:Locate undergroundutilities away from rootsystems. Trenching cancause irreparable damageto roots. Employ tunnelingor trenchless technologiesto promote non-destructiveinstallation and inspection ofutility infrastructure.

soils:Avoid compaction of soilsduring construction. Ideal soilsfor the planting area are sandyloam for good drainage orstructural soils if located understreets or sidewalks.

planter size:For continuousplanters, allow six feet minimum

width for minor streets andeight feet minimum width formajor streets. For tree wells,the minimum area should be 5x 10.

street


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SpreadConstruct tree box filters alongthe right-of-way to filter andattenuate stormwater runoffduring one to two-year stormevents. Connect in a series orto rain gardens using perforatedpipe to handle larger events. TreeBox Filter pp. 176-177

Skinny StreetsCreate narrower streets to reduce runoff loadingand substitute pervious paving for impervious

surfaces to encourage stormwater infiltration.

Residential street design standards dating back to the1960s called for local street widths as high as 36 feet.Miles of American streets have been designed and builtto these standards, which are now recognized as unsafe,and an unwise use of fossil fuel-based resources. Widestreets generate large stormwater runoff peak loads due totheir extensive impervious surface area. Since the 1990s,many cities have revisited their street design standards,subsequently adopting narrower street profiles, some asnarrow as 20 feet wide for low traffic volumes, while still

accommodating emergency vehicle access.

Reducing the width of streets provides a number ofbenefits. While many may initially assume they areunsafe, these narrow roads, or skinny streets actuallyreduce average speeds and vehicle accident rates. Forinstance, a 24 foot wide street has about 0.32 accidentsper mile per year, while a 36 foot wide street has 1.21(Walker Macy - Villeboisv.4). Economic benefits includereduced street maintenance and resurfacing costs, whileenvironmental benefits include reduced urban heat islandeffect. Soft-engineered streets provide stormwater runoffattenuation and filtering. However, such facilities handleonly one to two-year storm events, requiring connection

to a treatment network for larger events. SoakUse curb extensions to retrofitexisting parking lanes with raingardens. This reduces impervioussurface area, and encouragesinfiltration during 10 to 25-yearstorm events. Rain Garden pp.178-179

infiltration

infiltration

infiltration

evapotranspiration

SlowCut curbs to allow for stormwaterflow into curb extensions orother LID facilities. Flow ControlDevices pp. 148-149

street


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Siskiyou StreetPortland, Oregon

infiltration

curbextension

non-invasive facultative landscapes

heat island mitigation

erosion control andsediment retention

climate regulation


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Connect open spaces to create an urban greenwaythat maintains nutrient, natural resource, and

habitat flows through the city.

Greenways are an essential connective tissue in openspace networks. These pathways preserve and restorenature in urban developments, and have the ability torevitalize underutilized urban sectors. Their delivery ofecological, economic, and social services ensure theirfavored status as important planning tools. While openspace networks will be enjoyed at a local level, regionalcoordination is often essential for comprehensive design

solutions using an ecological approach to development.

Besides creating value for abutting properties andgenerating economic activity, greenways providealternative transportation systems free of traffic conflict,and are ideal for casual transit and recreation. Theyalso improve health by accommodating active livingand physical activity. Greenways are key to large-scalestormwater treatment and flood protection, acting asvegetated buffers and flood basins that minimize property

damage from flooding.

Besides use of the greenway as an agricultural belt or a

rails to trails conversion, its most significant incarnationis the riparian buffer. A riparian buffer is part of a largersystem known as the riparian corridor, which consists of afloodplain, stream banks, and a stream channel. Riparianbuffers are important ecotones between land and water,offering unique habitat while regulating sediment inputsfrom upland land uses. Riparian buffers are essential to

sustaining healthy streams and watersheds.

Greenwaysevapotranspiration

refugia/habitat

filtration

cultural enrichment

SpreadUse vegetated riparian buffersto filter and attenuate urbanstormwater runoff before reach-ing sensitive stream corridors.Riparian Buffer pp. 180-181

SoakMaintain natural sinuosity instreams to create erosion anddeposition zones that regulatestream flow and sedimentation.

SlowImplement flow control devicessuch as curbs and level spreadersto slow the flow of water beforereaching the greenway. FlowControl Devices pp. 148-149

100 minimum300 maximum

infiltration

open space


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The Facilities Menu organizes the LID facilities based onincreasing level of treatment service (quality) as well asincreasing level of volume reduction (quantity). Therefore,number one (1), flow control devices offer the least amountof treatment services while number twenty-one (21),constructed wetland offers the most. Most municipalitiesrequire drainage infrastructure to manage 100-year stormevents. Though one facility alone will likely not satisfyperformance requirements, facilities with varying levels ofservice in a treatment network will provide superior levels

of treatment and volume reduction.

8

rainwaterharvesting

oversizedpipes

1

flow controldevices

2

detentionpond

5

7

retentionpond

wet vault

6

increasinglevelofvolumereduction

4

undergrounddetention

LID facilities menu

from mechanical

filter strip

9

tree boxfilter

16

dry swale

3

constructedwetland

21

bioswale

19

raingarden

17

infiltrationtrench

15

infiltrationbasin

20

riparianbuffer

18

vegetatedwall

12

11

surface sandfilter

undergroundsand filter

10

vegetatedroof

13

to biological

flow control detention retention filtration infiltration treatment

perviouspaving

14

What are the LIDfacilities?


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detentionpond

5

Detention ponds, or dry ponds, are stormwater basins designed tointercept stormwater runoff for temporary impoundment and gradual

release to a conveyance system or a receiving waterbody.

Detention ponds are designed to completely evacuate water from storm events,usually within 24 hours. They primarily provide runoff volume control reducingpeak flows that cause downstream scouring and loss of aquatic habitat. As ageneral rule, detention ponds should be implemented for drainage areas greaterthan 10 acres. On smaller sites it may be difficult to provide control since outletdiameter specifications needed to control small storm events are small and thusprone to clogging. Also, treatment costs per acre are reduced when implemented

at larger scales.

Re-suspension of settled material is a large concern in these systems, requiringperiodic sediment, debris, and pollutant removal. Detention ponds do not provideinfiltration and are therefore best used within a network that provides biological

treatment.

optimal level of servicedetention

location in LID network downstream of catchment

and runoff, upstream from off-sitestormwater management systems

scalewatershed runoff area

of 10 acres and greater

management regime regular trash and intermittent

sediment removal, pollutantsaccumulate in soils and may requireamendments and clean out

References:Low Impact Development Manual for MichiganMinnesota Urban Small Sites BMP Manual

Detention Pond

50-year

100-year

10-year

25-year

2-year

detention area

metered discharge

outlet

inlet pipe

inlet debrisgrate

emergencyoverflow

outlet pipe

riprap for flowattenuation

metered dischargeoutlet


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8

retentionpond

A retention pond, also known as a wet pool or wet pond, is aconstructed stormwater pond that retains a permanent pool of water,

with minor biological treatment.

Wet ponds remove pollutants through biological uptake processes and sedimentation.The amount of pollutants that are removed from stormwater runoff is proportionateto the length of time runoff remains in the pond, as well as the relation of runoff toretention pond volume. Since retention ponds must maintain a permanent pool, theycannot be constructed in areas with insufficient precipitation or highly permeablesoils, unless the soil is compacted or overlain with clay. Generally, large contributing

watersheds are required to maintain permanent pool levels.

One advantage of a retention pond is the presence of aquatic habitat when properlyplanted and maintained. The use of a pond aerator is necessary to avoid stagnationand prevent algae growth that can lead to eutrophication, or an anaerobicenvironment. A heathy aerobic environment is a necessary condition for aquaticlife and Integrated Pest Management (IPM). Regular maintenance inspections areneeded to ensure proper drainage, aerobic functioning and aeration, and vegetative

health. Trash, debris, and sediment will need to be removed periodically.

optimal level of service retention/treatment

location in LID network downstream of catchment

and runoff, usually constructedat the lowest point of the site

scale can be used for residential, commercial,and industrial sites, with watershed runoff

areas no smaller than 10 acresdepending on regional precipitation

management regimeinspected semiannually to confirm that

drainage is functioning properly and toremove sediment, accumulated trash, anddebris

References:Low Impact Development Manual for MichiganMinnesota Urban Small Sites BMP ManualEPA Storm Water Technology Fact Sheet-Wet Detention Ponds

Retention Pond

compressor

emergent plants

overflow

sediment storagevolume

compressed air tubing

pond aerator

slope, 3:1 or less

100-year available storage50-year

25-year

normal water level

permanent pool4 average depth(10 maximum)


26/29

A rain garden is a planted depression designed to infiltrate stormwaterrunoff, but not hold it.

A rain garden is a type of treatment facility, commonly known as bioretention. Theprimary pollutant removal mechanisms are filtration by native vegetation throughphytoremedation processes that clean water as it passes through the facility. Raingardens contain layers of organic sandy soil, and mulch for vegetation. Low-maintenance plants are recommended for rain gardens based on their suitabilityto local climate, soil, and moisture conditions without the use of fertilizers andchemicals. Rain gardens are best applied on a relatively small scale. They work

well along driveways and in low lying areas of a property.

Rain gardens should be located at least 10 feet away from buildings to preventwater seepage into foundations or underneath houses, causing mold and mildewproblems. Also, location away from large trees allows exposure to sunlight so that

rain gardens may dry out between storm events.

optimal level of servicefiltration/infiltration/treatment

location in LID network

downstream of filtration facilities,but upstream of primary treatment facilities

scale 500 sq ft, to allow for adequate

irrigation between small storm events

management regime occasional removal of trash andpruning of vegetation

References:Low Impact Development Design StrategiesAn Integrated Design ApproachLow Impact Development Manual for MichiganLow Impact Development Technical Guidance Manual for Puget SoundUnited States Department of Housing and Urban DevelopmentMinnesota Urban Small Sites BMP Manual

raingarden

17

Rain Garden

vegetation; succulents,herbs, grasses

4 to 8 deep berm10 min. distance from foundation

area, 50 sq ft min.-500 sq ft max.

oldlawnsurface

amended soil mix

filter fabric3/4 gravel base

perforatedunderdrain

overflow

system poorly-drained or largestorm ev


27/29

optimal level of servicefiltration/infiltration/treatment

location in LID network downstream of all LID facilities,

before waterbodies

scale from 100 to 300 wide is most effective,however smaller widths may also be used

management regime trash and sediment removal as necessary,and occasional mowing in zone 3

A riparian buffer is a vegetated strip along the banks of movingbodies of water.

Riparian buffers are a simple, inexpensive way to protect and improve waterquality through local plant communities. Between 50 percent and 85 percentof stormwater pollutant loads can be filtered within 100 to 300 foot vegetationbuffers. Buffer strips structurally stabilize banks and shorelines to prevent erosionand slumping. Trees and shrubs provide shade to maintain consistent watertemperature necessary for the survival of some aquatic life. Width of the buffer isbased on surrounding context, soil type, size and slope of catchment area, and

vegetative cover.

Riparian buffers are most effective when combined with flow attenuation devicesthroughout a watershed in order to avoid high velocity flows into riparian bufferareas. Some management is required when riparian buffers are near urbandevelopment. Avoid disturbing Zone 1 as tree litter aids in flow control and

filtration.

References:Low Impact Development Manual for MichiganConservation Buffers: Design Guidelines for Buffers, Corridors, and Greenways

riparianbuffer

18

Riparian Buffer

zone 1: undisturbedforest streamside zoneconsists of fast-growingflood-tolerant trees andreedy plants that stabilizebanks and cool waterthrough shading

zone 2: managed foreconsists of slow-growingtrees and shrubs thatprovide wildlife habitat,and absorb remainingcontaminants from zone

zone 3: runoff controlconsists of perennialgrasses, with herbaceouand woody vegetation thslow runoff and absorbsmost contaminants


28/29

Manual Team Manual SponsorsUniversity of Arkansas

Community Design Center (UACDC)Stephen Luoni, Director

Steven L. Anderson Chair in Architecture and Urban StudiesCory A. Amos, Project Designer

Katie Breshears, AIA, LEED AP, Project DesignerJeffrey Huber, LEED AP, Project Designer

Cade Jacobs, Project DesignerStephen M. Reyenga, Project DesignerLinda Komlos, Administrative Specialist

Deborah Guzman, Student InternBecky Roark, Student Intern

University of ArkansasEcological Engineering Group

Dr. Marty Matlock, PESarah Lewis, Graduate Associate

Rusty Tate, Graduate AssociateZara Clayton-Niederman, Research Associate

Fay Jones School of ArchitectureJeff Shannon, AIA, Dean

Manual ReviewersBobby Hernandez, USEPA Region Six

Dr. Carl Smith, CMLI, UA Department of Landscape ArchitectureChristopher Suneson, ASLA, APA, LEED AP

Katie Teague, UA Agricultural Extension Services

with

Western

Branch

Funding was made available in part by the Arkansas NaturalResources Commission (ANRC) through a grant from the UnitedStates Environmental Protection Agency (USEPA) Region 6

Section 319(h).

Publication was made possible by generous support from:

Arkansas Forestry Commissions Urban Forestry Programand US Forest Service

Beaver Water DistrictLowell, Arkansas

Community Foundation of the Ozarks andStewardship Ozarks InitiativeSpringfield, Missouri

Ozarks Water Watchwith Upper White River Basin FoundationBranson,Missouri

National Center for Appropriate TechnologySoutheast Field Office: Fayetteville, Arkansas

US Green Building CouncilWestern Branch Arkansas Chapter: Northwest Arkansas

Illinois River Watershed Partnership

Northwest Arkansas and Northeast Oklahoma

C O M M U N I TY F O U N D ATI O N

O F T H E O Z AR K S

UWRB:UpperWhiteRiverBasin Foundation

Beaver

Water

District

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Our space planning should take itscue from the patterns of nature itselfthe water table, thefloodplains, the ridges, the woods, and above all, the streams.

William Whyte, The Last Landscape

Documents

26LID Manual Book Sample