SvR High Point presentation


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A presentation by SvR on the natural drainage system and green infrastructure aspects of the High Point redevelopment.

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SvR High Point presentation

  1. 1. Civil Engineering Landscape Architecture Environmental Restoration Planning High Point Redevelopment & Natural Drainage System Kathryn Gwilym, PE, LEED ® AP Tom von Schrader, PE, LEED ® AP
  2. 2. High Point Revitalization Project <ul><li>Developer: Seattle Housing Authority </li></ul><ul><li>120-acre mixed income housing redevelopment </li></ul><ul><li>34 blocks of new streets with new utilities, street trees, sidewalks, parks and open space </li></ul><ul><li>Up to 1,600 housing units, neighborhood center, library and mixed-use block </li></ul>Mithun Architects + Planners High Point Prior to Redevelopment <ul><li>Density ranges from 16 to 30 units/acre of ground-related housing </li></ul>
  3. 3. Priority Watershed- Longfellow Creek <ul><li>High Point Subbasin: 8% of Longfellow Creek Watershed </li></ul><ul><li>High-priority, salmon-bearing watershed that has been identified by “the community and the City as a significant and valuable resource” (Seattle Public Utilities) </li></ul><ul><li>Urban Watershed that drains to Puget Sound </li></ul>Longfellow Creek Longfellow Creek watershed High Point basin
  4. 4. Natural Drainage System (NDS) Strategies – where we started in 2002 <ul><li>Partnership of Seattle Housing Authority & Seattle Public Utilities </li></ul><ul><li>Design Charrette with City Departments </li></ul><ul><li>Vegetated, shallow grass and grass conveyance swales along 15,000 lf streets </li></ul><ul><li>Traditional storm drain conveyance pipe for large storm events </li></ul><ul><li>Stormwater pond for Flood Control </li></ul><ul><li>Reduce Impervious Surfacing </li></ul><ul><li>Disperse Runoff at Source </li></ul>
  5. 5. Drainage Criteria & Goals for High Point <ul><li>Water quality treatment: 6 month Seattle storm </li></ul><ul><li>Conveyance sizing for 25-year Seattle storm </li></ul><ul><li>Peak flow control for 2, 25 and 100 year Seattle storm events </li></ul><ul><li>Conveyance of dam safety flows downstream of stormwater pond </li></ul><ul><li>NDS combined with the stormwater pond detain and match duration up to the 2 year , 24-hour storm assuming pasture conditions </li></ul>
  6. 6. Challenges for Developing Street Section: Having space for all users & infrastructure in ROW ↑ Drainage Swale Concept ↑ Electrical & Franchise Utilities
  7. 7. ROW Street Section with NDS Swale <ul><li>The cross sections for the NDS swales were developed through discussions with various City of Seattle departments (decisions by inches) </li></ul><ul><li>Street widths: 25 feet/56 right of way; 28 feet/56 ft rw; 32 feet/60 ft rw </li></ul><ul><li>Curb height, swale width, street tree locations, berm locations, side slopes, bottom width, etc. were established </li></ul><ul><li>Porous sidewalks on the swale side </li></ul>
  8. 8. Developing Cross Section & Swale Length in ROW <ul><li>Vegetated swale </li></ul><ul><li>5’+/- compost gravelly soil </li></ul><ul><li>18” deep, 10” ponding </li></ul><ul><li>Grass-lined swale </li></ul><ul><li>5’ +/- compost gravelly soil </li></ul><ul><li>8” deep, 2” ponding </li></ul>
  9. 9. High Point Swales <ul><li>Vegetated </li></ul><ul><li>Grass-lined </li></ul><ul><li>Conveyance </li></ul><ul><li>Amended soils </li></ul>
  10. 10. Seattle Public Utilities’ First Public Porous Cement Concrete Pavement Street at 32 nd Ave SW <ul><li>Integration between redevelopment and adjacent single family neighborhood </li></ul><ul><li>Road: 8” porous concrete over 18” gravel storage subbase </li></ul><ul><li>Collaboration between suppliers, designers, City Inspectors, Contractors, Neighbors and Seattle Housing Authority </li></ul><ul><li>Being Monitored by Seattle Public Utilities </li></ul>
  11. 11. 32nd Avenue SW Porous Cement Concrete Street Prior to Construction Post Construction Placing Concrete
  12. 12. Natural Drainage Strategies – Housing Block-level Design <ul><li>High Point Drainage Technical Standards and requirements for each lot per the plat </li></ul><ul><li>Examples of Methods to use: </li></ul><ul><ul><li>Porous pavement </li></ul></ul><ul><ul><li>Conveyance furrow </li></ul></ul><ul><ul><li>Dispersal trench </li></ul></ul><ul><ul><li>Rain garden </li></ul></ul><ul><ul><li>Pop-up emitter </li></ul></ul><ul><ul><li>Downspout Disconnect </li></ul></ul><ul><ul><li>Reduce Impervious footprint </li></ul></ul>
  13. 13. Housing Sites Drainage Dispersion, Splashblocks, Rain Gardens & Art Splash Blocks by Myersculpture
  14. 14. Stormwater Pond <ul><li>Receives 130 acres of run-off </li></ul><ul><li>Flow control for 100-year storm event </li></ul><ul><li>Water Quality Treatment in combination with NDS swales </li></ul><ul><li>Depth 15.5’, Storage 22 ac-ft </li></ul><ul><li>Dam Safety </li></ul><ul><li>Park Amenity & Art </li></ul>
  15. 15. How High Point Works & Informing the Community
  16. 16. High Point has <ul><li>… proven installations that are now being applied across the country </li></ul><ul><ul><li>Low Impact Design/Site Drainage Technical Standards </li></ul></ul><ul><ul><li>Reduced impervious footprints </li></ul></ul><ul><ul><li>Mature tree protection techniques </li></ul></ul><ul><ul><li>Site fully integrated with Low Impact Development techniques </li></ul></ul><ul><ul><li>Reduced road widths </li></ul></ul><ul><ul><li>Site-wide pedestrian circulation and safety enhancements </li></ul></ul><ul><ul><li>Use of porous paving applications for walks, road and parking lots </li></ul></ul>
  17. 17. High Point has <ul><li>… proven installations that are now being applied across the country </li></ul><ul><ul><li>Multifunctional stormwater park </li></ul></ul><ul><ul><li>Menu driven low impact development approach </li></ul></ul><ul><ul><li>Defined permitting review process </li></ul></ul><ul><ul><li>Interagency collaboration </li></ul></ul><ul><ul><li>Community education </li></ul></ul><ul><ul><li>Resident education </li></ul></ul><ul><ul><li>Maintenance and operation standards </li></ul></ul><ul><ul><li>Art integration </li></ul></ul><ul><ul><li>Aesthetic treatment of drainage swales </li></ul></ul>Sandblasting by Myersculpture
  18. 18. Recognition: Seattle Housing Authority Seattle Public Utilities Other agencies: Washington State Department of Ecology US Department of HUD Seattle Department of Planning and Development Seattle Department of Transportation Seattle City Light Seattle Parks Department Artist: Myers Sculpture For more information: and Seattle Public Utilities had a vision for a neighborhood with a naturalistic drainage approach. Seattle Housing Authority had a vision for a diverse, sustainable neighborhood. These two public agencies have worked hard to implement these visions. Consultants: SvR Design Company Mithun Architects and Planners Resource consultants: Shannon and Wilson RW Beck & Herrera Nakano Associates Stoneway Concrete Cedar Grove Composting NW ACPA Ph I Natural Drainage System Contractors: Gary Merlino Construction T. Yorozu Gardening Co. Absher Construction Fardig Ph II Natural Drainage System Contractors: Tri-State Construction Inc. T. Yorozu Gardening Co.