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Green Roadway LID


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Gordon’s winning Green Roadway LID Design Competition presentation. This presentation is a 5 minute timed slide show and was presented at VMI’s 23rd Annual Environment Virginia Symposium. The competition was funded through a grant from the National Fish and Wildlife Foundation and the project sponsors included James River Association, Friends of the Rappahannock, and Potomac Conservancy.

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Green Roadway LID

  1. 1. BalancingNature & Neighborhood 1 1
  2. 2. Design Process 2Site Base Review Design Final Establish Brainstorm Goals ConceptVisit map Requirements priorities details Design Balance of professionals • Landscape Architects • Civil Engineers
  3. 3. Existing Residential Neighborhood 3• 17 residences and only14 driveways• Unrestricted on-street parking for a total of 39 +/- spaces• The road is crowned with a single low point• Existing trees do not form a consistent tree canopy
  4. 4. Existing Parking 4Zoning Requirements Single family dwellings: 1 space/ residenceExisting Parking:14 Driveway Spaces: 14 spacesOn Street Spaces: 39 spacesTotal Spaces: 53 spacesExisting Parking Ratio: 3.1 spaces/ residence
  5. 5. LID Strategies 5Our team explored a variety of LID techniques beforedetermining the best LID measures that seemed fitting forthe existing conditions of this neighborhood.These included: • Decrease impervious area • Converting pavement into bio-retention areas • Use pervious pavement • Reduce traditional storm water infrastructure • Encourage parking in existing paved areas • Use of native/ adapted plants • Use decentralized LID’s
  6. 6. LIDStrategies 6
  7. 7. LID Strategies Site Plan 7 Zoning Rqmt : 1 space/residence Existing Parking: 14 Driveway Spaces: 14 spaces On Street Spaces: 39 spaces Total Spaces: 53 spaces Existing Parking Ratio: 3.1 spaces/ residenceProposed Parking:14 Driveway Spaces: 14 spacesOn Street Spaces: 30 spacesTotal Spaces: 44 spacesProposedParking Ratio: 2.6 spaces/ residenceLoss of 9 on-street parking spaces
  8. 8. LID StrategiesLandscape Plan 8 • Overhead power lines on North side of street • Use of small to medium street trees • Uniform street tree canopy to compliment existing trees
  9. 9. Landscape Palette 9 Liquidamber styraciflua ‘Rotundiloba’ (Rotundiloba Sweetgum) Betula nigra Nyssa sylvatica Red Maple (River Birch) (Black Tupelo) (Acer rubrum)Gleditsia triacanthos inermis ‘Imperial’(Imperial Honeylocust) Myrica pensylvanica (Northern Bayberry) Clethra alnifolia ‘Hummingbird’ (Sweet Pepperbush)Ilex glabra ‘Shamrock’(Shamrock Inkberry) Spireae tomentosa Ilex verticillata ‘Nana’ (Steeplebush) (Red Sprite Winterberry)Eupatorium fistulosum Phlox stolonifera Aster divaricatus (Joe Pye Weed) (Creeping Phlox) (Dwarf Aster) Deschampsia caespitosa Iris versicolor (Tufted Hairgrass) (Harlequin Blueflag)Native, low maintenance, and durable in urbanand bioretention environments
  10. 10. Balancing Nature & Neighborhood 10• Using Stormwater to provide Neighborhood character• Attractive and native landscaping• Interconnected LID practices
  11. 11. LID StrategiesBioretention Planting 11
  12. 12. 12LID Strategies Bioretention
  13. 13. LID Strategies Pervious Pavement 13The Green Roadwayconverts asphalt intopervious pavement.Bioretention planters areused in series andinterconnected throughan underdrain system.
  14. 14. LID Strategies SWM (Quantity Control) 14 Highlights Design Event Scenario Peak Discharge Peak Discharge Reduction Percentage (Green VS. (cfs) Existing) • No reliance on infiltration, applicable to any Forested Condition 2.23 soil condition 5 -yr Existing Condition 5.13 58.48% • No Adjusted/ reduced Curve Numbers due Green Roadway 2.13 to pervious pavement or runoff reduction • No Flooding: 100-YR Runoff is contained Peak Peak Discharge Reduction Design Event Scenario Discharge Percentage (Green VS. (cfs) Existing) within LID practices Forested Condition 3.15 10-yr Existing Condition 6.17 61.91% Green Roadway 2.35 12.00 Peak Peak Discharge Reduction Design Event Scenario Discharge Percentage (Green VS. 100-YR Storm Hydrographs (cfs) Existing) 10.00 Forested Condition 7.67 Existing Condition 100-yr Existing Condition 10.79 73.86% 8.00 Green Roadway 2.82Discharge (cfs) Green Roadway 6.00 4.00 2.00 0.00 540 600 660 720 780 840 900
  15. 15. LID Strategies SWM (Quality Control) 15SummaryPhosphorus Removal (based on Virginia Runoff Reduction Worksheet) Highlights Phosphorus Phosphorus Leaving the Site Phosphorus Removed Phosphorus Phosphorus Phosphorus Load Removed by Reduction Percentage Scenario by Pervious Pavement Leaving the Site Removal Bioretention (Green Roadway VS. Existing (lb/yr) (lb/yr) (lb/yr) (lb/yr) Percentage Condition) • 90% PhosphorusExisting Condition 1.79 0.00 0.00 1.79 0% removal Green Roadway 1.64 0.50 0.96 0.18 89% 90% • Approach utilizedNitrogen Removal (based on Virginia Runoff Reduction Worksheet) Runoff Reduction Nitrogen Load Nitrogen Removed by Nitrogen Removed Nitrogen Nitrogen Nitrogen Leaving the Site Reduction Methodology Pervious Pavement by Bioretention Leaving the Site Removal Percentage Scenario (Green Roadway VS. Existing Percentage (lb/yr) (lb/yr) (lb/yr) (lb/yr) Condition)Existing Condition 12.77 0.00 0.00 12.77 0% 91% • Phosphorus and Green Roadway 11.70 3.55 6.99 1.16 90% Nitrogen reductions helps meet BayRunoff Reduction (based on Virginia Runoff Reduction Worksheet) TMDLs Treatment Volume Runoff Leaving the Site Reduction Runoff Reduced by Runoff Reduced by Runoff Leaving Runoff (Runoff from 1" Percentage Scenario Pervious Pavement Bioretention the Site Reduction Rainfall) (Green Roadway VS. Existing Percentage (cf) (cf) (cf) (cf) Condition)Existing Condition 2,841 0 0 2,841 0% Green Roadway 2,603 605 1,503 495 81% 83%
  16. 16. Cost Analysis 16$600,000 Highlights LID Conventional • Conventional Cost assumed use of a$500,000 conventional sand filter for Quality$400,000 Control and an underground$300,000 concrete vault for Quantity Control.$200,000 • Conventional Cost$100,000 resulted in additional cost for pavement $- and storm drainage Site Pavement Curb, Edging Storm Landscaping Total systems Preparation and Sidewalks Drainage Systems • LID Design resulted in increased costs for The LID Design resulted in savings of $125K for 715LF curbing and of roadway construction. landscaping.
  17. 17. Conclusion 17• innovative design, real world solution through interconnected decentralized facilities• Enhanced quality of life through landscaping• mimics natural hydrologic function of the site and will help meet Bay TMDL’s• lower construction costs compared to conventional design