Seattle s Natural Drainage Systems and Complete Streets NACTO Designing Cities 2016
Outline Set stage Seattle and systems How Seattle has utilized bioretention to protect water systems Pathways for project implementation SPU CIP s Regulatory outcomes Stormwater code Consent decree Right of Way Improvements Manual Complete Streets Green Streets
Seattle Map of Drainage Watersheds
Projects in ROW The ROW is 27% of our land area and the focus of our CIPs
SEA Street First Major Project
Bioretention on Curbless Streets
Broadview Green Grid Natural Drainage System Before construction After Construction
Bioretention on Curbed Streets
Seattle GSI Implementation Tools GSI Design Manuals Manuals to support CIP design Volume I: Project Initiation Phase Volume II: Options Analysis Volume III: GSI Design Phase Volume III: Construction Volume IV: O&M Volume V: Monitoring Project phase flow charts Sequence of tasks 9
Seattle GSI Implementation Tools Standard GSI Details & Specs Standard details Permeable pavement Bioretention sections (earthen slopes and vertical walls) Bioretention curb cuts, presettling cells, pit drains, drilled drains Specifications Bioretention soil Concrete sidewalk Slotted underdrain pipe and aggregate blanket 10
Seattle is interested in a National Guidance Manual Vehicular and Pedestrian Safety for GSI
Long Term Control Plan - NDS Partnering Program Streets shown in pink are potentially technically feasible for a natural drainage system. Pipers Creek Watershed Thornton Creek Watershed IMPORTANT: SPU is funded to build projects on about 4% of these blocks. This means we will be able to build natural drainage systems on a small sub-set of potentially feasible blocks. Watershed Begin Design Begin Construction Longfellow 2017 2019 Thornton 2018 2019 Pipers 2019 2020 Longfellow Creek Watershed
NDS Partnering
Neighborhood co-benefits water pollution prevention + Traffic Calming New Street Trees Beauty Sidewalk
Seattle GSI Requirements Stormwater Code Applies to all Types of Projects: Parcel & Single Family Residential Trail/Sidewalk Roadway
Seattle GSI Requirements On-site Stormwater Management On-site stormwater management BMPs used to infiltrate, disperse, and retain stormwater runoff on-site to the extent feasible without causing flooding or erosion impacts. Project thresholds: 2,000 sf new plus replaced hard surface, or 7,000 sf of land disturbing activity 16
Code Implementation Projects
Streets Illustrated: 10-Year Update Right-of-Way Improvements Manual 19
Project objectives of the 10-year update Reflect best practice street design Strike balance between specificity and flexibility Develop clear and illustrative graphics Reflect right-of-way allocation priorities Engage and align with City departments (SPU, SFD, etc.) Advance community-led initiatives Bike design standards Green Stormwater Infrastructure design standards 20
Green Stormwater Infrastructure- Design Guidance- Side slopes
Green Stormwater Infrastructure- Design Guidance- walled bioretention
Existing GSI Projects in Seattle 23
Supporting Policies In July 2013, City Council unanimously passed Resolution 31549: GSI should be relied upon to manage stormwater wherever possible Target to manage 700MG annually with GSI by 2025 City Departments shall collaborate with OSE to produce Implementation Strategy for meeting new target
Complete Streets: Policy, Tools, Outcomes
Seattle s Complete Streets policy Complete Streets policy adopted by City ordinance in 2007 South Columbian Way Before Transportation improvements will include an array of facilities and amenities that are recognized as contributing to Complete Streets, including: street trees, landscaping and natural drainage Insert image South Columbian Way After
Transportation elements Street types Modal plan recommendations Pedestrian Master Plan Transit Master Plan Bicycle Master Plan Freight Master Plan Transportation plans/studies Neighborhood/land use plans Intelligent Transportation Systems needs Sidewalk/pavement repair needs
Urban design elements Place-making opportunities Material selections (e.g., enhanced paving treatments) Street trees and landscape enhancements Green stormwater infrastructure Pedestrian-scale lighting Public art
Operationalizing Complete Streets
Green Street Program
Downtown Green Streets
Pedestrian Focus
Abundant landscaping and amenities
Sustainable elements
Unique features and art.
Enhance open space
Public Private Partnerships
Discussion / Questions More information or follow-up questions: www.seattle.gov/util/naturaldrainage Shanti Colwell shanti.colwell@seattle.gov Susan McLaughlin susan.mclaughlin@seattle.gov
We try to be Clear on what is allowable Public and Private Projects Utility Lead Retrofit / Capital Improvement Projects
Built Examples of Natural Drainage Systems in Seattle North Seattle West Seattle West Seattle
This is our pollution and our water This is our street and our water Ours to understand Ours to clean. This is our creek and our water This is our home and our water Ours to protect. Ours to love.
Urban GSI Walls and Wiers Seattle Times
How do natural drainage systems work? Dirty road runoff flows into a landscaped area and is slowed down as it soaks in through the plants and soil water passes through fluffy soil and is cleaned Cleaned water is released to Longfellow Creek