1 / 19

Vegetated Swales in Residential Developments

Term Project Presentation CE 394K.2 Hydrology Presented by Chelsea Cohen Thursday, April 24, 2008. Vegetated Swales in Residential Developments. What is a Vegetated Swale?. Low Impact Development (LID) Technique Mimic natural landscape Open, shallow channels Slow Runoff

oshin
Télécharger la présentation

Vegetated Swales in Residential Developments

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Term Project Presentation CE 394K.2 Hydrology Presented by Chelsea Cohen Thursday, April 24, 2008 Vegetated Swales in Residential Developments

  2. What is a Vegetated Swale? • Low Impact Development (LID) Technique • Mimic natural landscape • Open, shallow channels • Slow Runoff • Lower Velocities • Promote Infiltration • Filter Runoff • Trapezoidal or Parabolic Shape • Long, narrow, vegetated channels

  3. Objectives • Model 25-yr and 100-yr design storms • Flood Control • Decentralized vs. Centralized System • Vegetated Swale vs. Detention Pond • Minimize Downstream Flow Off-Site • Conveyance • Contrast to Traditional Curb and Gutter • Aesthetic Appeal in Community

  4. Design Criteria • Seattle Street Edge Alternatives (SEA) • Pilot project along residential street • Wisconsin DOT Technical Standard • California Storm Water BMP Handbook • San Francisco Drainage Calculations • City of Austin Drainage Criteria Manual

  5. Precipitation • Synthetic Storm • SCS Type III Rainfall Distribution • 25-yr, 24-hr, 7.63in • 100-yr, 24-hr, 10.18in

  6. Subcatchment Properties • Six ¼ -acre lots in series • 2% Slope • Infiltration: SCS Runoff Curve Number • Assumed Type C Soil for moderately fine to fine soils • Pre-development: CN=74 • Open space, Good Condition, Grass cover >75% • Post-development: CN=83 • Residential, ¼ acre, 38% impervious

  7. Vegetated Swale Geometry • Longitudinal Slope Range: 0.5%-4% • 1% Vegetated Swale Slope • Side Slope 3H:1V or flatter • Swale Bottom 2 to 8-ft • 5-ft Bottom • 25-ft Width • 116-ft Length • Dense Grass Cover • n=0.25 25’ 3H:1V 5’

  8. Culvert Geometry • Connect vegetated swales with culverts • Sizes: 6” and 10” PVC pipes • 0.5% Pipe Slope

  9. Model Site Layout • Safety Barrier between pedestrians and motorists

  10. SWMM Modeling Software • EPA’s Storm Water Management Model (SWMM) • Rainfall-Runoff simulation model used for single event or long-term (continuous) • Simulation of Runoff quantity and quality from primarily urban areas • Iterative Process

  11. Animation: 25-yr Model

  12. Animation: 100-yr Model

  13. Compare Models • Design Iteration between Swale Size, Pipe Size and Storm Capacity 25-yr 100-yr

  14. Results • Infiltration: 13-17% • Post-Development Flow less than Pre-Development Flow • Provide Detention Storage in Swales • No increase in peak flow as a result of development

  15. Results (cont.) • Low swale velocity to prevent scour and promote infiltration • Swales do NOT over top for 25-yr or 100-yr storms

  16. Aesthetic Appeal • Design the ROW to be beautiful as well as useful • Neighborhood Enjoyment and Care • Common destination for neighborhood residents • Add native vegetation • Seattle Street Edge Alternative (SEA) Project • Reduced total volume of storm water flow leaving the street by 99%

  17. Future Work • Water Quality Improvement • Cost Benefit • Compare to Curb and Gutter System • Application to Entire Neighborhoods

  18. Conclusion • Management of Rainfall • Filter and Slow the Flow of Storm Water • Increase safety if convey 100-yr storm in swale and not roadway • Cost Effective and Aesthetically Pleasing • Responsible Design • Environmental Benefits • Methods to minimize developmental effects • Attempt to mimic natural landscape prior to development

  19. Questions?

More Related