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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.
2
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
0
5
10
15
20
25
Total Nitrogen
lb/a
c/yr
Forest
Res (½ ac)
Industrial
Commercial
0
0.5
1
1.5
2
2.5
3
Total Phosphorus
lb/a
c/yr
Forest
Res (½ ac)
Industrial
Commercial
0
0.05
0.1
0.15
0.2
0.25
TSS
tons
/ac/
yr Forest
Res (½ ac)
Industrial
Commercial
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 SwaleBioretention 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 micromanagingstormwater throughout the site.
Park stormwater detention basinalso 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
0
10
20
30
40
50
60
70
10:00 AM 11:00 AM 12:00 PM 1:00 PM 2:00 PM 3:00 PM 4:00 PM 5:00 PM
cfs
2-yr 24-hr storm
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.
25
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.
28
“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
32
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
34
High Quality Green Area: Which do we want to encourage?
35
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
Greener Infrastructure - Triple Bottom Line Benefits
Carbon Sequestration Offsetting Annual carbon emissions from autos or Single family homes
Reduced Energy Use Reduction of kWh in energy use and energy savings
Greener Infrastructure - Triple Bottom Line Benefits
Load Reductions and Runoff Benefits TSS removed per year Reduction in runoff
Groundwater recharge
Greener Infrastructure - Triple Bottom Line Benefits
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