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Green Infrastructure: Case Studies in Seattle

Field Trip Leaders:Danielle Bogardus, Joe Puleo,

Andres Morales, Ed Nebendahl

What is Green Infrastructure?

Water management infrastructure

Goal is preserve, maintain, or improve natural hydrological cycles

Mimicking natural environments using engineered systems

Rain gardens, permeable surfaces, green roofs, and roof gardens

https://www.americanrivers.org/threats-solutions/clean-water/green-infrastructure/what-is-green-infrastructure/

Photo Credit: Jacob Dyste

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Why use Green Infrastructure?

Can be applied in small and large scales

Natural systems work better than “man-made” systems

Investment in green infrastructure can save money in the long run

Must protect quality of life, safety and health

Create jobs and stimulate the economy

Rain Gardens

“A rain garden is a planted depression or a hole that allows rainwater runoff from impervious urban areas, like roofs, driveways, parking lots, and compacted lawn areas, the opportunity to be absorbed.” -Wikipedia

A form of Bioretention

Temporarily store rainwater and runoff to clean the water of unwanted hydrocarbons, heavy metals, oil, fertilizers, and other pollutants

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Aspects to a Rain Garden

Shallow depression

Planted with native plants that have deep rootsGrasses

Native plants are adapted to the area

If a drought occurs, the deep rooted plants can reach down to access the lower water table

Located near a downspout, driveway, or runoff location

Goal is to collect the water before it enters the sewer system or watershed Natural filtration system

Slows the speed of the water

Soil in a Rain Garden

High infiltration ratesSand-Sandy loamStore some in the pores but then allows the rest to flow to the groundwater

A gravel bed is beneficial at the bottom where soil has slow infiltrationGravel allows for more storage, and prevents water pooling at the surface

Overflow structureRock lined notch in the bermGrass lined swaleDepends on if erosion from overflow is a concern

Do not build a Rain Garden in soil that has a high water table

Do not build a Rain Garden within 10 feet of infrastructure

Do not build a Rain Garden on a slope greater than 15%

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What are Green Roofs?

NOT roof gardens

Layers of waterproofing membranes, root barriers, drainage and irrigation systems

Completely or partially covered in soil or growing medium

Vegetation

Text & Image: Green Roofs for Healthy Cities website http://www.greenroofs.org/index.php/about/aboutgreenroofs

Benefits of Green Roofs

Opportunities for social, economic, and environmental benefits

Private stakeholder expendituresIncrease property valueImprove roofing material longevity

Ecosystem servicesReduce pollutants/runoff entering bodies of waterIncrease carbon sequestrationDecrease urban heat island effectImprove air quality

Improve human wellbeinghttp://www.seattle.gov/Documents/Departments/OSE/Green-Roofs-In-Seattle.pdf

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Permeable Pavement For Green Parking Lots

https://www.youtube.com/watch?v=1fKGwbpgLJg

● Permeable Paving○ Concrete

only 30% smaller than ⅜” aggregate○ Asphalt same as concrete○ Pavers

● Use in conjunction with natural drain-age landscapes like bioswales and rain gardens

● Help meet water quality and flow control requirementshttp://www.seattle.gov/DPD/Publications/CAM/CAM515.pdf

Permeable Pavement Uses

● Residential: Walks, Patios, Driveways

● Commercial: Pedestrian Plazas, City Sidewalks, Parking Lots

● Streets: Residential and Collector

● Not recommended for High Speed Highways, >35mph

●http://www.psp.wa.gov/downloads/LID/20121221_LIDmanual_FINAL_secure.pdf

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Permeable Paving Limitations

● Flat grades 2% or flatter, maximum slope 5%

● Needs to be engineered

● Avoid using where a seasonal high groundwater is near the surface

● Avoid using where there is routine sanding during winter months

● Minimize sediment from adjacent areas

● Avoid use on USDA type D soil (soils with a clayey texture) greater than 40% clay and less than 50% sand. Have a high runoff potential and a depth to water impermeable layer less than 20 inches.http://www.seattle.gov/DPD/Publications/CAM/CAM515.pdf

Urban Agriculture - Roof Gardens

→ Green spaces containing gardens and/or recreational areas constructed on roofs of commercial, residential, and industrial buildings.

Includes perennial gardens, lawns, walkways, benches, tables, putting greens, shrubs and

trees, rooftop farming, etc.

Growing in popularity due to environmental, societal, and financial benefits

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Ecological Benefits of Roof Gardens

Provides food and plants for consumption

Provides habitats for wildlife (i.e. pollination for insects, branches for birds to perch, etc.)

Improves air quality by reducing CO2 in air and producing oxygen through photosynthesis

Decreases stormwater runoff which can improve water quality

http://www.bestroofing.net/brv2/wp-content/uploads/2015/06/Benefits-of-a-Garden-Roof-1.png

Urban Benefits of Roof Gardens

Decrease pollution from stormwater runoff

Makes efficient use of limited urban space for cultivating crops

Increases life span of roof membranes

Temperature control reduces need for Air Conditioning

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Societal Benefits of Roof Gardens

Recreational activity and social health benefits

Provides shade for walking or lounging

Aesthetics

Saves money through less air conditioning/building maintenance

Green Roofs vs. Roof Gardens

Roof Garden Green Roof

Principal Use Recreation/AgricultureEnergy Efficiency/ Protective Layer

Maintenance/Cost High Low

AccessibilityWalkable and

high accessibilityLow to no accessibility

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Field Trip Sites

What to Look For?

A.B. Ernst Park

Permeable Paving

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http://bestseattleparks.com/wp-content/uploads/2009/12/IMG_1993.JPG

http://jennyheishman.com/public/img/etCetera/publicWorks/waterMover.jpg

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Up-Garden P-Patch Community Gardens

Roof Gardens

http://mediad.publicbroadcasting.net/p/kplu/files/styles/x_large/public/201206/UPGarden%20Landscape%20Plan%20Labeled%20-%20Final.jpg

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http://www.erichigbee.net/wp-content/uploads/2014/08/UpGarden1_Ehigbee_1200px-690x458.jpg

UW Biological Sciences Building

Rain Gardens

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UW Husky Union Building

Green Roof/Rain Gardens

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Husky Union Building Green Roof

Xero Flor Technology SystemPre-vegetated mat

Moss and sedum in growing medium

Retention fleeceDesigned to store and distribute water throughout the root zone

Drain matAllows excess water to drain below the vegetated layer

Root barrierPlastic layer over waterproofing membrane to prevent root damage to building

http://www.xeroflora.com/green-roof-system/xero-flor-green-roof-features/

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http://www.xeroflora.com/green-roof-system/xero-flor-green-roof-features/

Sources

1)http://www.raingardennetwork.com/blog/what-is-a-rain-garden/

2)http://www.fairfaxcounty.gov/nvswcd/raingardenbk.pdf

3)http://www.bestroofing.net/infographics/benefits-of-garden-roofs-infographic/