Kimberly Brewer Tetratech: Stream Stewardship

February 11, 2012

Stream StewardshipWhat we’re doing well.Ideas from other communities.

Kimberly Brewer, AICP

There’s a lot we’re doing well…

Chapel Hill’s stormwater performance standards (particularly volume control); Resource Conservation District Ordinance for stream buffers

Carrboro’s water quality buffers and village mixed use standards Orange County’s Flexible Development Ordinance for Conservation Design UNC’s stormwater standards for Central Campus and cutting-edge plans for

Carolina North Drinking Water Supply Protection standards Urban Services Area boundary and Rural Buffer Orange County’s Land Legacy Program for land preservation Carrboro and Chapel Hill’s 5,000 sq.ft. threshold for stormwater

management Tree protection standards Progressive Sedimentation and erosion control standards Etc.

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5 Key Points – To be more successful we need to…

Address uncontrolled runoff from existing development

Be realistic about what can be achieved in restoring our streams

Build on our strong stormwater performance standards

Consider new incentives and requirements for green practices

Select practices that provide multiple benefits

Watershed Improvement- Getting at the Existing Impairment of Our Streams

Development Impacts: Runoff Volume

Typical pre-development conditions:

Runoff = 10% Infiltration = 50%

Typical post-development conditions:

Runoff = 55% Infiltration = 15%

Development Impacts: Overland Pollutant Loading

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Total Phosphorus

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A word of caution. New research shows…

Most stream restoration efforts are unsuccessful. Focusing on isolated stream reaches, Ignoring what’s upstream and runoff from the watershed Removing tree canopy and disturbing riparian areas

Most urban stream restoration efforts promise more than they can achieve. Ignoring real biological and water quality potential

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Redevelopment Standards

New State Jordan Lake Stormwater Rules for redevelopment have stricter stormwater capture and treatment standards and streamside vegetation rules

As existing development in Carrboro, Chapel Hill, and Orange County redevelops, the Rules will also benefit local streams.

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How can we proactively reduce impacts from existing development?

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Neighborhood Streets Retrofits

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Green practices aren’t just pretty gardens….

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Dry Well Vegetated Swale Bioretention Area or Raingarden

Downtown Streetscape Retrofits

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DOT Highway Retrofits

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Public Property Retrofits

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School micromanaging

stormwater throughout the site.

Park stormwater detention basin

also serving as playing field.

Private Property Retrofits

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Look around. You’ll see lots of retrofit opportunities…

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Other Ideas

Downspout Disconnect Programs

Better Sewer Easement Maintenance

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How can we pay for these retrofits?

State DOT- Local Partnership Stormwater fees

Chapel Hill has a fee; Carrboro doesn’t Wastewater utility fees (Fayetteville, Ark., Portland,

Philadelphia, etc.) Trading (Washington, D.C) Private-Public Cost Sharing (Raleigh)

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Wastewater Utility Fee Example Fayetteville Ark

State proposed strict, costly wastewater discharge Phosphorus limit.

Agreed to allow the treatment plant to continue to meet current limit IN EXCHANGE FOR reducing nonpoint source loading in watershed.

The City agreed to pay $200,000/yr for retrofit and restoration projects.

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Trading Program Example Washington D.C.

Washington D.C. Stormwater Retention Trading Program Increases retention of stormwater at all regulated

development Dense downtown areas allowed to purchase credits Less dense regulated and unregulated areas can install

BMPs that generate retention credits Provides more flexibility and cost-effectiveness

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Cost-Share Program Example City of Raleigh

Up to 50-50 cost-share for private development BMP retrofits for existing development BMPs on new construction Must go beyond regulatory requirements

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Bioretention Area

Watershed Protection- Performance Standards for New Development

Traditional Thinking

Old wisdom: Treating the first inch of runoff and managing the peaks of stormwater is enough.

Now we know it’s not.

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Changes in Flow

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10:00 AM 11:00 AM 12:00 PM 1:00 PM 2:00 PM 3:00 PM 4:00 PM 5:00 PM

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Existing

Post, no BMPs

Conventional Detention

Performance Standard Gap

Carrboro and Orange County: Volume Control Example Language from Chapel Hill Ordinance“The stormwater runoff volume leaving the site post-development shall not exceed the stormwater runoff volume leaving the pre-development site (existing conditions) for the local 2-year frequency, 24-hour duration storm event for all development.” except certain residential development existing 1/27/03.

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Jordan Lake Stormwater Rules – What’s New?

Nutrient loading limits for all new development and redevelopment In addition to treatment of 1st inch and peak control

Protection of existing riparian buffers – 50 feet of vegetation – no clearing, grading, or development (existing lawns are exempted)

Also applies to state and federal entities, e.g. DOT

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HOW We’re Meeting Performance Standards- Ideas for Greener Approaches

The Green Factor and Green Area Ratio: Seattle and Washington D.C.

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“Green Area Ratio (GAR) is the ratio of the weighted value of

landscape elements to land area. The GAR score relates to an

increase in the quantity and quality of environmental performance

of the urban landscape”.

Pictures courtesy Laine Cidlowski

Green Area Ratio Benefits

Increases the amount and quality of urban landscaping in dense urban areas Also applicable to low and moderate density zones

Allows increased flexibility for developers and designers to efficiently use their properties

Builds on stormwater requirements

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GREEN AREA RATIO LANDSCAPE ELEMENTS MULTIPLIERLandscaped area (select one of the following for each area)Landscaped areas with a soil depth of less than 24 in. 0.3Landscaped areas with a soil depth of 24 in. or more 0.6Bioretention facilities 0.4PlantingsGround covers, or other plants less than 2 ft tall at maturity 0.2Plants at least 2 ft tall at maturity 0.3Tree canopy for all trees 2.5 in. to 6 in. in diameter 0.5Tree canopy for new trees 6 in. in diameter or larger 0.6

Tree canopy for preservation of existing trees 6 in. to 24 in. in diameter 0.7

Tree canopy for preservation of existing trees 24 in. diameter or larger 0.8Vegetated wall, plantings on a vertical surface 0.6Vegetated roofs

Extensive vegetated roof over at least 2 in. but less than 8 in. of growth medium 0.6

Intensive vegetated roof over at least 8 in. of growth medium 0.8Water features (using at least 50% recycled water) 0.2Permeable pavingPermeable paving over at least 6 in. and less than 2 ft of soil or gravel 0.4Permeable paving over at least 2 ft of soil or gravel 0.5Enhanced tree growth systems 0.4Renewable energy generation (area of) 0.5BonusesNative plant species 0.1Landscaping in food cultivation 0.1

Graphic courtesy Laine Cidlowski

Green Area Ratio: How Does it Work?

How to calculate: Add up landscape elements by

number or size # trees Size of green roof Size of rain garden # of plants Soil depths

Divide by lot area

= GAR score

Graphic courtesy Laine Cidlowski

What would we need to do to get a higher Green Area Ratio? At minimum….

Revise ordinances to eliminate barriers: Landscaping Screening Setbacks Open Space Right-of-Way

Evaluate/select practices we want to encourage

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What would we need to do to get a higher Green Area Ratio? Being more proactive..

Evaluate the “ratio” we want in different zones Existing green area ratio by town districts/zones Cost sensitivity

Provide incentives or requirements to meet Green Area Ratio

Cost of Green Area Ratio requirements in dense urban areas (Seattle, Washington D.C.) Typically 0.5% of total construction costs Consistently less than 1.0% of total construction costs

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Greenprinting – Three Types

Site Design Based Enhanced green features

Land Conservation Based Natural heritage sites, trails, open

space, parks, community gardens, farmland preservation

Sustainable Development Based Open space, water resources,

urban design, energy, materials, transportation

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High Quality Green Area: Which do we want to encourage?

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Healthy environmentHealthy economyHealthy community

Triple Bottom Line

Job Creation Jobs for skilled and unskilled workers Present worth of reduction in social costs

Reduced Infrastructure Costs

Greener Infrastructure - Triple Bottom Line Benefits

Increased Property Values Median 4% increase

Increased Recreational Opportunities


Carbon Sequestration Offsetting Annual carbon emissions from autos or Single family homes

Reduced Energy Use Reduction of kWh in energy use and energy savings


Load Reductions and Runoff Benefits TSS removed per year Reduction in runoff

Groundwater recharge


February 11, 2012

(1) Address uncontrolled runoff from existing development

(2) Be realistic about what can be achieved

(3) Build on our strong stormwater performance standards

(4) Consider new incentives/requirements for green practices

(5) Select practices that provide multiple benefits

Amenity and comfort ratings are ______% higher for a tree-lined sidewalk compared to a non-shaded street. 20% 60% 80%

Triple Bottom Line Analysis – Other Benefits

Desk workers who can see nature from their desks experience approx ___% less time off sick. 10% 25% 45%

Triple Bottom Line Analysis - Other Benefits

Study of green space amenity values related to customers’ price valuation, participants priced goods ____% higher in landscaped districts. 3% 9% 12%


Survey of one community, _____% of the public preferred to patronize commercial establishments whose structures and parking lots have trees and landscaping. 50% 75% 100%


People make more walking trips when they are aware of natural features, and judge distances to be greater than they actually are in less green neighborhoods. True False


Kimberly Brewer Tetratech: Stream Stewardship

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