Kimberly Brewer Tetratech: Stream Stewardship

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Friends of Bolin Creek Water Symposium Feb. 2012

Adjunct to CH2020 process.

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  • Provides a menu of landscape elements and establishes a minimum score for new development.In addition to conventional landscape elements, menu includes green roofs, vegetated walls, pervious paving, and bonuses for public visibilityIncreases the amount of landscaping required, while also increasing design flexibilityIncrease the amount and quality of urban landscaping in dense urban areas while allowing increased flexibility for developers and designers to efficiently use their properties:Builds on DDOE stormwater requirementsApplicable to low & moderate density zonesFlexibleConsistentHigher environmental valueProvides targets based on relative level of urbanism
  • Kimberly Brewer Tetratech: Stream Stewardship

    1. 1. Stream StewardshipWhat we’re doing well.Ideas from othercommunities. Kimberly Brewer, AICP February 11, 2012
    2. 2. 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
    3. 3. 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
    4. 4. Watershed Improvement-Getting at the ExistingImpairment of Our Streams
    5. 5. Development Impacts: Runoff VolumeTypical pre-development Typical post-developmentconditions: conditions: Runoff = 10% Runoff = 55% Infiltration = 50% Infiltration = 15%
    6. 6. Development Impacts: Overland Pollutant Loading 25 3 20 2.5 Forest 2 Forest lb/ac/yr lb/ac/yr 15 Res (½ ac) Res (½ ac) 1.5 10 Industrial Industrial 1 Commercial Commercial 5 0.5 0 0 Total Nitrogen Total Phosphorus 0.25 0.2 Forest tons/ac/yr 0.15 Res (½ ac) 0.1 Industrial Commercial 0.05 0 TSS
    7. 7. 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 7
    8. 8. 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. 8
    9. 9. How can we proactively reduce impacts fromexisting development? 9
    10. 10. Neighborhood Streets Retrofits 10
    11. 11. Green practices aren’t just pretty gardens…. Dry Well Vegetated Swale Bioretention Area or Raingarden 11
    12. 12. Downtown Streetscape Retrofits 12
    13. 13. DOT Highway Retrofits 13
    14. 14. Public Property Retrofits School micromanaging stormwater throughout the site. Park stormwater detention basin also serving as playing field. 14
    15. 15. Private Property Retrofits 15
    16. 16. Look around. You’ll see lots of retrofit opportunities… 16
    17. 17. Other Ideas Downspout Disconnect Programs Better Sewer Easement Maintenance 17
    18. 18. 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) 18
    19. 19. 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. 19
    20. 20. 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 20
    21. 21. 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 requirementsBioretention Area 21
    22. 22. Watershed Protection-Performance Standards forNew Development
    23. 23. Traditional Thinking Old wisdom: Treating the first inch of runoff and managing the peaks of stormwater is enough. Now we know it’s not. 23
    24. 24. Changes in Flow 2-yr 24-hr storm 70 Existing 60 Post, no BMPs 50 Conventional Detention 40cfs 30 20 10 0 10:00 AM 11:00 AM 12:00 PM 1:00 PM 2:00 PM 3:00 PM 4:00 PM 5:00 PM
    25. 25. 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 volumeleaving the pre-development site (existing conditions) for thelocal 2-year frequency, 24-hour duration storm event for alldevelopment.” except certain residential development existing1/27/03. 25
    26. 26. 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 26
    27. 27. HOW We’re MeetingPerformance Standards-Ideas for Greener Approaches
    28. 28. The Green Factor and Green Area Ratio: Seattle andWashington D.C. “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”. 28 Pictures courtesy Laine Cidlowski
    29. 29. 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 29
    30. 30. 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 0.6Tree canopy for preservation of existing trees 6 in. to 24 in. in diameter 0.7Tree canopy for preservation of existing trees 24 in. diameter or larger 0.8Vegetated wall, plantings on a vertical surface 0.6Vegetated roofsExtensive vegetated roof over at least 2 in. but less than 8 in. of growth medium 0.6Intensive 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
    31. 31. 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 scoreGraphic courtesy Laine Cidlowski
    32. 32. What would we need to do to get a higher Green AreaRatio? At minimum…. Revise ordinances to eliminate barriers:  Landscaping  Screening  Setbacks  Open Space  Right-of-Way Evaluate/select practices we want to encourage 32
    33. 33. What would we need to do to get a higher Green AreaRatio? 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 33
    34. 34. 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
    35. 35. High Quality Green Area: Which do we want to encourage? 35
    36. 36. Healthy environmentHealthy economyHealthy communityTriple Bottom Line
    37. 37. Greener Infrastructure - Triple Bottom Line Benefits Job Creation  Jobs for skilled and unskilled workers  Present worth of reduction in social costs Reduced Infrastructure Costs
    38. 38. Greener Infrastructure - Triple Bottom Line Benefits Increased Property Values  Median 4% increase Increased Recreational Opportunities
    39. 39. 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
    40. 40. Greener Infrastructure - Triple Bottom Line Benefits Load Reductions and Runoff Benefits  TSS removed per year  Reduction in runoff Groundwater recharge
    41. 41. (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 February 11, 2012
    42. 42. Triple Bottom Line Analysis – Other Benefits Amenity and comfort ratings are ______% higher for a tree-lined sidewalk compared to a non-shaded street.  20%  60%  80%
    43. 43. Triple Bottom Line Analysis – Other Benefits Amenity and comfort ratings are ______% higher for a tree-lined sidewalk compared to a non-shaded street.  20%  60%  80%
    44. 44. Triple Bottom Line Analysis - Other Benefits Desk workers who can see nature from their desks experience approx ___% less time off sick.  10%  25%  45%
    45. 45. Triple Bottom Line Analysis - Other Benefits Desk workers who can see nature from their desks experience approx ___% less time off sick.  10%  25%  45%
    46. 46. 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%
    47. 47. 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%
    48. 48. Triple Bottom Line Analysis - Other Benefits Survey of one community, _____% of the public preferred to patronize commercial establishments whose structures and parking lots have trees and landscaping.  50%  75%  100%
    49. 49. Triple Bottom Line Analysis - Other Benefits Survey of one community, _____% of the public preferred to patronize commercial establishments whose structures and parking lots have trees and landscaping.  50%  75%  100%
    50. 50. Triple Bottom Line Analysis - Other Benefits 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
    51. 51. Triple Bottom Line Analysis - Other Benefits 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

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