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ASCE LID Conference September 27, 2011 Ballard Roadside Rain Garden’s:

ASCE LID Conference September 27, 2011 Ballard Roadside Rain Garden’s: What Went Wrong and How we Recovered. City Sewer System. Combined and Partially Separated (2/3 of City) Separated (1/3 of City). Typical Basins by Land Use. Overview . GSI Accomplishments. GSI Accomplishments .

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ASCE LID Conference September 27, 2011 Ballard Roadside Rain Garden’s:

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  1. ASCE LID ConferenceSeptember 27, 2011 Ballard Roadside Rain Garden’s: What Went Wrong and How we Recovered

  2. City Sewer System • Combined and Partially Separated (2/3 of City) • Separated (1/3 of City)

  3. Typical Basins by Land Use Overview

  4. GSI Accomplishments

  5. GSI Accomplishments • CIP projects: Past pilot, now program • Utility lead and Public/Private Partnering Projects • 232 acres restored to natural hydrology. • $18M Roughly $100K/acre. • GSI O&M Manual; defined Levels of Service; Restoration protocol • Redevelopment incentives/requirements • Design Guidance and concept details in Right-of-way improvement manual • Stormwater Code. November 2009 adopted GSI to MEF requirement. • Rates based on impervious surfaces. Rate credit for BMPs. GSI higher credits • Green Factor requirement • RainWise Rebates; $4/SF mitigated • Ongoing Adaptive Management • Greenroof monitoring, hoping to increase credits

  6. Ballard Roadside Raingarden, Phase 1 • Spend Stimulus $$; jobs • Pilot the application of bioretentionfor CSO reduction • Get started on the 3 years allocated to Green before Grey in CSO program • Where: • NPDES 152 – 63 CSOs in 2010, approximately 40 million gallons of combined sewage

  7. Ballard GSI for CSO

  8. Project Goals • Develop design templates for future Roadside Raingardens • Planting strip design • Curb extension design • (Full curb shift) • Refine construction costs • Refine performance data • (Be like Portland)

  9. What Could Go Wrong?

  10. Timeline • Mar 2009 – began GSI siting and design • July – likely to receive ARRA (Stimulus) funds • July – First community meeting held • Aug 17th – formally awarded ARRA loan • Sept 17th – 90% Plans, Specs and Engineering Report required to be submitted • October 13th – Second community meeting held • November – Geotechnical Report finalized

  11. The Perfect Storm • Communication • Design • Construction timing along excessive rainy winter (even for Seattle)

  12. Communication • Inter team communication critical • Internal Knowledge Transfer critical • Although we’ve lead very inclusive community process with all previous projects, PM chose standard pipe CIP approach • Although SPU has overseen construction of 65-70 blocks for complete retrofit with bioretention, CM team had NO knowledge, training about bioretention. • Public Involvement Strategy • Project requires a lot of face time with community. Identify who that person will be & give them enough time • Work in residents front yard need a different model than standard CIP projects • No existing awareness of a problem

  13. Technical Design • Technical / Design Approach • Risks taken but not communicated or discussed with Team • Enthusiasm for trying to meet citizen traffic calming request took precedent over intended project scope (curb shift design and working on 28th without survey) • Unidentified Subsurface Geology Conditions

  14. 29th Ave NW & NW 77th St Raingarden Post-Construction Performance Infiltrating (drains in < 24 hours) Not infiltrating or infiltrating very slowly TP-111 0.1 in/hr TP-109 0.15 in/hr Raingardens not exactly to scale.

  15. 31st Ave NW between NW 75 & 77th St Raingarden Post-Construction Performance Infiltrating (drains in < 24 hours) Not infiltrating or infiltrating very slowly TP-108 0.5 in/hr Raingardens not exactly to scale.

  16. 28th Ave NW between NW 65th & 67th St TP-117 0.15 in/hr Raingarden Post-Construction Performance Infiltrating (drains in < 24 hours) Not infiltrating or infiltrating very slowly TP-118 0.1 in/hr NW 66th St TP-119 0.15 in/hr Raingardens not exactly to scale.

  17. 28th Ave NW between NW 71st & 72nd St Raingarden Post-Construction Performance Infiltrating (drains in < 24 hours) Not infiltrating or infiltrating very slowly Raingardens not exactly to scale.

  18. 30th Ave NW between NW 80th St & Loyal Way NW Raingarden Post-Construction Performance Infiltrating (drains in < 24 hours) Not infiltrating or infiltrating very slowly TP-104 1.2 in/hr Raingardens not exactly to scale.

  19. Bad Luck • Construction completion moved into wet season • Fall rains roughly double typical • Highly technically savvy neighbors

  20. Policy Clear political support Clear policy - especially around level of risk tolerated Signs Allowable swale depth and ponding depth 21

  21. Lessons Learned – Community Engagement • Get out into the community early and often • Introduce the problem before presenting the solution • Don’t rely just on the community meetings to engage the community and get feedback • Written questionnaire on wet basements & soggy yards • Projects with flexible siting require lots of rounds of community interface, because each meeting results in design changes that impact new people who haven’t been to the earlier meetings, and they too want to modify or eliminate the design • Don’t be fooled that just because you have a lot of fans at the planning stage, doesn’t mean you won’t have a lot of critics at final design/construction • Consider demonstration infiltration tests on evenings/weekends so skeptical neighbors can be eye witnesses.

  22. Lessons Learned – Community Engagement • Understand the neighborhood “look” • Curb and Gutter creates different community ownership of frontage than ditch & culvert areas • Be clear about: • Short term standing water and why it’s important. Puddles are good. Puddles may be present consistently for four months of winter • Loss of parking – impact to neighbor in front and other neighbors along the street. • Change in Aesthetics – during construction, end of construction, 1-yr later, 5-yrs later • Signs!!! • Staging has got to go in front of someone’s house

  23. Lessons Learned – Geotechnical • Follow Stormwater Code minimum infiltration feasibility guidance • Consider ratio of sidewall to bottom area during test and try to limit horizontal flow. • Consider potential for groundwater mounding on top of glacial till. • If test pits find <0.5 in/hr, Monitor groundwater levels for a minimum of one winter. • Ask community about evidence of groundwater springs, basement flooding, and other groundwater problems.

  24. Lessons Learned – Geotechnical • Whole project team works on site selection and design, including determination of appropriate level of data collection versus risk and cost. • Leave time for a 2nd round of tests if the initial tests suggest high levels of soil variability

  25. Lessons Learned – Design • Design should include backup system or at minimum a alternate concept in bid documents (underdrain) if design infiltration rate is less than 0.5 in/hr • If moving curbs, complete a “light” survey to capture critical elevations, but don’t skip survey • Don’t be cheap with the plants – buy some larger stock • Review project design and function and critical project elements with CM. Clearly articulate intent of “field directed” elements in the design. • Provide design for flow control/bypass plan and erosion control; sandbags aren’t adequate

  26. Lessons Learned – Construction • Bring geotechs out during construction to verify soils • Review project design goals and objectives with designer • Review flow control and erosion and sediment control requirements and expectations with designer to ensure cells are adequately protected

  27. Help I need Bioretention science and benefits one page simplified fact sheet Child Safety Studies/References How much bioretention dirt before human health concern Clear policy - especially around level of risk tolerated MUTCD Requirement “obstructions within the roadway shall be marked with a Type 1 or Type 3 object marker 28

  28. Questions? Tracy Tackett GSI Program Manager Seattle.gov/util/greeninfrastructure City of Seattle Seattle Public Utilities Ray Hoffman, Director

  29. 29th Ave NW & NW 77th St Original design TP-111 0.1 in/hr TP-109 0.15 in/hr Retrofit design Infiltrating raingarden Remove and convert back to planting strip Raingardens not exactly to scale.

  30. 31st Ave NW between NW 75 & 77th St Original design Infiltrating raingarden Low functioning raingarden TP-108 0.5 in/hr Remove and convert back to planting strip Retrofit design Raingardens not exactly to scale.

  31. 28th Ave NW between NW 65th & 67th St Original design TP-117 0.15 in/hr Infiltrating raingarden TP-118 0.1 in/hr Low functioning raingarden Raingarden converted to live storage with underdrain NW 66th St TP-119 0.15 in/hr Retrofit design Raingardens not exactly to scale.

  32. 28th Ave NW between NW 71st & 72nd St Original design Infiltrating raingarden Low functioning raingarden Retrofit design Raingardens not exactly to scale.

  33. 30th Ave NW between NW 80th St & Loyal Way NW Original design TP-104 1.2 in/hr Infiltrating raingarden Retrofit design Raingardens not exactly to scale.

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