Green Connection Lid 3 12 09

Sustainable Site Development:Land Development as Nature Intended

• Sustainable Urban Planning Policies

• Green Building Site Standards

• Low Impact Development Specifics

Michael Clark, PE, LEED AP

www.westonandsampson.com

Low Impact Development Specifics

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A more sustainable land development approach A more sustainable land development approach Based on an environmentally sensitive Based on an environmentally sensitive site planning process;site planning process;

andand A A stormwater management strategystormwater management strategy to mimic natural hydrology. to mimic natural hydrology.

An Introduction toAn Introduction to LOW IMPACT DEVELOPMENTLOW IMPACT DEVELOPMENT

Alternative Approaches to Stormwater ManagementAlternative Approaches to Stormwater Management

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Courtesy May, U of W

Natural Conditions

Hydrology 101

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Courtesy May, U of W

Developed Conditions

Hydrology 101

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• WHY IS L.I.D. NEEDED?– Maintain Natural Watershed characteristics

– Protect Recharge Areas and

– Ecological Integrity of Our Receiving Waters

– Control Water Quantity and Water Quality

– Restore / improve areas already developed

An Introduction to LOW IMPACT DEVELOPMENT

Alternative Approaches to Stormwater Management

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Better site design:

• to identify and preserve natural features;

• to maintain natural hydrology;

• to help respect abutter’s properties;

• to retain property values;

• to augment groundwater supplies;

• to maintain high water quality.

Local Authorities’ Perspective:

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The Problem

Conventional Development Smart Development

Reduce land clearing and grading costs

Reduced infrastructure costs

Protect regional water quality

Reduce stormwater runoff

The SolutionThe Solution

Impacts on open space

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Conventional Conventional DevelopmentDevelopment

Centralized Centralized Pipe and Pond Pipe and Pond ControlsControls

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LID LID DevelopmentDevelopment

Conservation Conservation Minimization Minimization Soil Soil Management Management Open Drainage Open Drainage Rain Gardens Rain Gardens Rain Rain Barrels Barrels Pollution Pollution Prevention Prevention

Disconnected Disconnected Decentralized Decentralized Distributed Distributed Multi-functional Multi-functional

Multiple SystemsMultiple Systems

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Conventional Low Impact

Functional Lanscape DesignGood Drainage

LID Site

Design

• Conservation of natural hydrology, trees, and vegetation

• Minimized impervious surfaces

• Dispersal of stormwater runoff

• Conservation of stream & wetland buffers

• Ecological landscaping

The standard planning process involves four-steps, after the yield is established.

Source: R. Arendt

Identify conservation value areas on the site such as wetlands, significant trees or tracts of forest, steep slopes, habitat, cultural resources or buffer zones. Remove these from the “developable area”.

1.

Source: R. Arendt

Place houses in the remaining area in a way that would maximize residents enjoyment of protected areas by providing access to open space and preserving views.

2.

Source: R. Arendt

Align roads and trails on the site to provide pedestrian and vehicle access and maximize stormwater management options.

3.

Source: R. Arendt

4. Draw lot lines around the homes.

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Reduce Stormwater Runoff, Treat Non-Point Source Pollution

– Site planning techniques (narrower roads, conserved natural areas, preserve natural

depressions)– Dry wells for rooftop runoff;– Grassed (vegetated) swales;– Filter buffer strips;– Soil Augmentation;– Bioretention areas;– Permeable pavers;– Green roofs;– Rain barrels and cisterns; and– Stormwater planters.

LID Best Management PracticesLID Best Management Practices

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Conservation Conservation

Open Open DrainageDrainage

Rain GardensRain Gardens

Amended Soils

Rain Rain BarrelBarrel

Lot Level Source Controls

LID Site LID Site Porous Porous Pavement Pavement

Create a Hydrologically Create a Hydrologically Functional LotFunctional Lot

Narrower Streets

20 Photo Copyright 1999, Center for Watershed Protection

Many roads are much wider than they need to be. Many roads are much wider than they need to be.

Better Site Design of Roadways & Parking AreasBetter Site Design of Roadways & Parking AreasBetter Site Design of Roadways & Parking AreasBetter Site Design of Roadways & Parking Areas

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0

2

4

6

8

10

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20 22 24 30 32 34 36 38 40 42 44 46 48 50

Street Width (ft)

Ac

cid

en

ts/M

ile/Y

ea

r

Number of Accidents as a Function of Residential Street Width

Source: Swift, et. al., 1998

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Better Site Design of Roadways & DrivewaysBetter Site Design of Roadways & DrivewaysBetter Site Design of Roadways & DrivewaysBetter Site Design of Roadways & Driveways

•Narrower streets

• Alternative cul-de sacs

• Shared driveways

•Narrower streets

• Alternative cul-de sacs

• Shared driveways

Source: City of Portland, OR

Source: CWP Sarasota, FL

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Better Parking Lot DesignBetter Parking Lot Design Green stripsGreen strips

provide shadeprovide shade can use for stormwater can use for stormwater

collection & treatmentcollection & treatment reduce need for large unsightly reduce need for large unsightly

detentiondetention enhance aestheticsenhance aesthetics

Reduce overall parkingReduce overall parking create multiple small lotscreate multiple small lots allow shared parkingallow shared parking reduce space sizereduce space size

Porous Pavement Porous Pavement (in outlying (in outlying overflow areas)overflow areas)

Sarasota FL

reduce runoff volumes reduce runoff volumes & reduce pollution& reduce pollution

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• Infiltration to replenish groundwater supplies and maintain baseflows to streams & wetlands;

• Less runoff and sediment to public drainage system = lower maintenance costs;

PROBLEM: Downspouts Connected to Driveway = More Runoff, Less Infiltration

OBJECTIVES:

Dry Well Infiltration of Roof

Runoff

SOLUTIONS:SOLUTIONS:

Rooftop Runoff to vegetated swale

Source: CWP

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Grassed Swales (aka “vegetated swales”)Grassed Swales (aka “vegetated swales”)

Provides better water quality treatment;Provides better water quality treatment; Reduces infrastructure (drainage) costs;Reduces infrastructure (drainage) costs; Reduces size and cost of detention basins;Reduces size and cost of detention basins; Is visible and affords better maintenance;Is visible and affords better maintenance; Aesthetics may increase property valuesAesthetics may increase property values

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Vegetated SwalesConveyance, Treatment, InfiltrationVegetated SwalesConveyance, Treatment, Infiltration

• Roadside swales (country drainage) for lower density and small-scale projects;

• For small parking lots;

• Mild side slopes and flat longitudinal slopes;

• Provides area for snow storage & snowmelt

treatment

• Roadside swales (country drainage) for lower density and small-scale projects;

• For small parking lots;

• Mild side slopes and flat longitudinal slopes;

• Provides area for snow storage & snowmelt

treatment

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Bioretention (Biofiltration)Treatment, Retention, Infiltration, Landscaping

Bioretention (Biofiltration)Treatment, Retention, Infiltration, Landscaping

• Excavation filled with engineered soil mix

• Herbaceous perennials, shrubs, trees

• Ponded water infiltrates within 72 hours

• Overflow outlet and optional underdrain

• Excavation filled with engineered soil mix

• Herbaceous perennials, shrubs, trees

• Ponded water infiltrates within 72 hours

• Overflow outlet and optional underdrain

Source: CWP

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BioretentionTreatment, Retention, Infiltration, LandscapingBioretentionTreatment, Retention, Infiltration, Landscaping

Ref: Preliminary Sarasota County LID Manual, 2008

Bioretention Plan View

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Soil / Flora / Fauna Soil / Flora / Fauna

Ecological StructureEcological Structure

A Dynamic Living A Dynamic Living Ecosystem Cycling Ecosystem Cycling Nutrients, Chemicals Nutrients, Chemicals and Organic Energy and Organic Energy SourcesSources

Plants, BacteriaPlants, Bacteria

Protozoa, FungusProtozoa, Fungus

Worms, InsectsWorms, Insects

MammalsMammals

.

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BioretentionApplicationsBioretentionApplications

• Parking lot islands

• Median strips

• Office parks

• Residential lots

• Parking lot islands

• Median strips

• Office parks

• Residential lots

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Bioretention AreaSmall parking lots

Bioretention AreaSmall parking lots

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BioretentionApplications

BioretentionApplicationsUrban retrofits

High-density areas

Urban retrofits

High-density areas

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• Grass pavers• Paving stones• Porous asphalt• Pervious concrete• Reinforced turf

• Grass pavers• Paving stones• Porous asphalt• Pervious concrete• Reinforced turf

Permeable PavingRunoff Reduction

Permeable PavingRunoff Reduction

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Permeable PavingApplications


• Parking stalls

• Overflow parking

• Driveways

• Walkways and plazas

• Parking stalls


• Driveways


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• Parking stalls


• Driveways


• Parking stalls


• Driveways


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Green Roof SystemsRunoff Reduction, Reduced Heating / Cooling CostsGreen Roof SystemsRunoff Reduction, Reduced Heating / Cooling Costs

• Rainwater stored in a lightweight engineered soil

medium;• Hardy, drought-resistant

vegetation;• Reduces runoff by 50%.

Not recommended in watersheds where baseflows are already diminished.

• Rainwater stored in a lightweight engineered soil

medium;• Hardy, drought-resistant

vegetation;• Reduces runoff by 50%.

Not recommended in watersheds where baseflows are already diminished.

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Green Roof SystemsGreen Roof Systems

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Rain Barrels and CisternsRunoff Reduction and Water Conservation

Rain Barrels and CisternsRunoff Reduction and Water Conservation• Downspouts directed to tanks or barrels;

• 50 –10,000 gallons;

• Excess diverted to drywell or rain garden;

• Landscaping, car washing, other non-potable uses.

• Downspouts directed to tanks or barrels;

• 50 –10,000 gallons;

• Excess diverted to drywell or rain garden;

• Landscaping, car washing, other non-potable uses.

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Large-Scale Applications

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Stormwater PlantersRunoff Reduction, Treatment, Attenuation

Stormwater PlantersRunoff Reduction, Treatment, Attenuation

• “Bioretention in a Box”

• Vegetative uptake of stormwater

pollutants

• Pretreatment for suspended solids

• Aesthetically pleasing

• Reduction of peak discharge rate

• “Bioretention in a Box”

• Vegetative uptake of stormwater

pollutants

• Pretreatment for suspended solids

• Aesthetically pleasing

• Reduction of peak discharge rate



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Stormwater PlantersStormwater Planters

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Cohasset L.I.D. Stormwater Retro-Fit Project

Lily Pond is Cohasset Drinking Water SupplyLily Pond is Cohasset Drinking Water Supply

Control of discharges to Lily Pond required to protect public health andControl of discharges to Lily Pond required to protect public health andensure safe Drinking Water Supplyensure safe Drinking Water Supply

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Cohasset Stormwater LID Project

• Project Goals

1. Reduce Nutrient Loading

2. Reduce Other Pollution– Suspended solids, organic pollutants, oils

3. Help Prevent Catastrophic Contamination

4. Public Education / Demonstration Project

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Demonstration Raingarden at Lily Pond Treatment Plant– Designed to intercept flows from parking lot

discharging directly to Lily Pond.– To be used as a Public Outreach Tool to

educate community.– Planted with a mix of communities and age

plants.

Cohasset Stormwater LID Project

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Site prior to excavation

Cohasset Stormwater LID ProjectDemonstration Raingarden at Lily PondDemonstration Raingarden at Lily Pond

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Biorentention Soil Mixing

Cohasset Stormwater LID ProjectCohasset Stormwater LID ProjectDemonstration Raingarden at Lily PondDemonstration Raingarden at Lily Pond

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Excavation


52UnderdrainUnderdrain


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Graded FilterGraded Filter

54Placement of Placement of Bioretention Soil MixBioretention Soil Mix


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Planting June 2005


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First Rain Storm


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September 2005


Environmental and Community

• Protects unique or fragile habitats

• Reduces the pollution impacts of stormwater runoff

• Promotes aquifer recharge

• Provides opportunities to link wildlife habitats

• Conservation values are part of the planning process

• Can further goals of open space and community development plans

The planning process inherently protects natural resources, minimizes direct and untreated stormwater runoff to water bodies, and promotes recharge to underlying aquifers.

LID BENEFITS

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Benefits for Implementing at Local Levelo Eliminate or minimize large detention basinsoReduce Infrastructure requiring town maintenance

(reduced clearing, grading, paving, pipes, ponds)o Improve water qualityoReduce floodingo Preserve natural featureso Encourage “functional” landscapes

o SWM controls become part of property owners’ landscapeo reduces public burden for centralized SWM facilitieso on-lot cost and scale of maintenance is affordable

An Introduction to LOW IMPACT DEVELOPMENT

Alternative Approaches to Stormwater Management

Green Connection Lid 3 12 09

Technology

Transcript of Green Connection Lid 3 12 09