Green Stormwater Infrastructure (GSI)

HOW DOES IT WORK? Green Stormwater Infrastructure (GSI)

Program Overview and Annual Report 2013 What is GSI? WHAT IS GSI? Green stormwater infrastructure (GSI) mimics natural eco- logical function by cleaning, slowing, and/or reducing runoff close to where it falls as rain. GSI uses infiltration, evapora- tion, filtration or rainwater harvesting and reuse. When used in the public right-of-way (street and planting strip), GSI may 4 be referred to as “natural drainage 1 bioretentionsystems.” (like rain gardens)

GSI projects are designed to fit 2 within permeable/porous a broader, integrat pavement- 3

ed network of drainage systems 3 that green function roofs at the block 5 scale, neighborhood scale and city/regional scale. GSI 6 1 elements may be paired with conventional 4 urban canopy “gray” cover infrastruc- 2 ture, like underground pipes, tanks, and pumps, and can 5 rainwater harvesting (like cisterns) WHAT IS GSI? be designed to support urban livability goals like pedestrian safety. GSI also helps ensure our 6 urban soil building drainage (like mulch systems + compost) can adapt to climate changes, like more severe or more 7 biofiltration 1 frequent storms.

4 Where is GSI used? 1 bioretention (like rain gardens) Seattle’s Stormwater Code 1 requires developers 2 to use 3 GSI 4 5 6 7 “to the maximum extent feasible” to manage stormwater 2 permeable/porous pavement 3 runoff. The Code defines right-of-way and parcel thresh- olds and also outlines which types of projects to use. Some 3 green roofs 5 GSI technologies, such as rain gardens, cannot be used in 6 1 urban canopy cover places with steep slopes, contimated soil or soils that do not 4 2 drain. In these places, underdrains, green roofs, tree plant- 5 rainwater harvesting (like cisterns) ing/retention and rainwater harvesting and reuse may be used instead. City departments and community partners are 6 soil building (like mulch + compost) also building GSI retrofit projects on private property and in the public right-of-way to improve habitat and water quality 7 biofiltration 1 in our creeks, lakes, and Puget Sound.

What problems does GSI address? In the parts of Seattle where stormwater and TOO MUCH RUNOFF VOLUME wastewater combine in one underground pipe, GSI is designed to reduce the volume of storm- ...that causes flooding, sewer backups, & sewage overflows 1 water getting 2into the system, 3 particularly during 4 5 6 7 the peak of the storm. Reducing this “peak flow” of stormwater volume helps prevent flooding, sewer backups, and sewage overflows into wa- terways. Seattle is under a consent decree with the EPA to reduce the number of sewage overflows to no more than one overflow per outfall TOO MUCH POLLUTION per year. ...that damages our creeks, lakes, and Puget Sound In other parts of Seattle, polluted stormwater runoff discharges directly into our city creeks (like Thornton Creek, Pipers Creek and Longfel- low Creek) and lakes (like Lake Union and Lake Washington). In these areas, GSI is designed to filter and break down pollutants in the stormwater and to slow the water down, so it does not damage stream banks and channels. Healthy water- ways provide critical habitat for salmon and other aquatic life. Why use GSI?

GSI systems are proven drainage and water quality technologies designed to achieve the specific goals of a drainage area.

GSI also provides many community benefits. When bud- gets are tight and space in the urban environment is limited, multi-benefit infrastructure is a high-value investment.

YES MAYBE Improves Pedestrian Safety + Experience + Experience Safety Pedestrian Improves Value Increases Property Mitigates Heat Island E ect Beauties Neighborhoods Improves Water Quality Water Improves Flooding Flow/Prevents Decreases Infrastructure Capacity Gray Preserves Water Conserves Potable Groundwater Recharges Carbon / Reduces Energy Saves Quality Air + Health Improves Sequesters Carbon Supports Habitat Biodiversity/Improves O ers Educational Opportunities

Green Infrastructure

Green Stormwater PROGRAM HISTORY S Green StormwaterInfrastructure PROGRAM HISTORY S Infrastructure 2000Program - 2012 History // 2000-2012 City of Seattle 2000 - 2012 City of Seattle 1 2000 - SEA Streets 2005-2009 - Highpoint Redevelopment 4 1 20002000 - //SEA SEA Streets Street 2005-20092005-2009 - Highpoint //Redevelopment Highpoint 4 Working in close collaboration with the Seattle Housing The city’s first natural drainage system was constructed in WorkingSeattle in close built collaboration neighborhood-scale with the Seattle GSI Housing into ThisThe city’s“Street first naturalEdge drainageAlternatives” system was project constructed col -in Authority, Washington State Department of Ecology, and the Broadview neighborhood to protect Pipers Creek from 3 Authority,many Washington other partners, State Department Seattle built of neighborhood-scale Ecology, and GSI the Broadview neighborhood to protect Pipers Creek from 3 manythe other129-acre partners, High Seattle Point built neighborhood-scale Housing Redevel GSI - the harmfullected effects stormwater of stormwater from runoff, across to provide 2.3 acres storm- into the 129-acre High Point Housing Redevelopment Proj- the harmful effects of stormwater runoff, to provide storm- 1 2 intoopment the 129-acre Project High Point by Housing partnering Redevelopment with ProjSHA- waterandwater conveyance, showed conveyance, anda 99 and to percent improveto improve thereduction the streetscape streetscape in run withwith- 1 2 ect. High Point’s natural drainage system design included sidewalks. Known as SEA Streets (Street Edge Alternative), ect.and High WA Point’s Department natural drainage of systemEcology. design Aincluded tradi - offsidewalks. volume. Known SEA as SEAStreet Streets became (Street Edge an Alternative), interna- extensiveextensive roadside roadside raingardens, raingardens, saved over saved a hundred over a hundred the projectthe project collected collected stormwater stormwater from from across across 2.3 2.3 acresacres 3 tional piped street drainage system would tional model for natural drainage projects 3 legacylegacy trees +trees planted + planted three thousand three thousand more, and more, inte- and inte- and showedand showed a 99 a percent 99 percent reduction reduction in inrunoff runoff volume. volume. SEASEA gratedhavegrated porous required porous concrete a concrete detention sidewalks. sidewalks. To pond acheive Towith compaacheive five- compa- StreetsandStreets became was became thean international anfirst international GSI project model model forimplemented for natural natural draindrain-- 5 5 rable rable stormwater stormwater benefit benefit with a traditional with a traditional piped street piped street age projects, now known as green stormwater infrastruc- times the volume to achieve the same age projects,in the public now known right-of-way as green stormwaterin the U.S. infrastruc- 6 6 drainagedrainage system systemwould havewould required have requireda detention a detentionpond pond ture (GSI). ture (GSI). withresult. fivewith times five the times volume. the volume.

20032003 - //Carkeek Carkeek Cascade Cascade 2 20032 - Carkeek Cascade 2010 // RainWise2010 - RainWise2010 Pilot - RainWise 5 Seattle introduced an incentive program known as Rain- 5 TheSeattle Cascade doubled the collects size of its runoff next GSI from project, across the Car 28- SeattleSeattle introduced introduced an theincentive RainWise program knownpro- as Rain- Seattlekeek doubled Cascade the (on size NW of 110th its next St.), GSIalso project,in the Pipers the Creek Car- Wise to provide rebates to eligible property owners who Wise to provide rebates to eligible property owners who keek acresWatershed.Cascade and (on The reduced NW Cascade 110th runoffSt.),collects also volumerunoff in the from Pipers by across up Creek to28 constructgram ato rain gardenprovide or install rebates a cistern onto their prop prop-- Watershed.74acres percent. and The reduced Cascade Post-construction runoff collects volume runoff by up from monitoringto 74 across percent. 28 erty.erty Moreconstruct owners than 100a rain homeownerswho garden construct or installed install thesea cisterna GSI fearainon -their prop- tures during RainWise’s first two years. Collectively these acresIn and addition reduced to holding runoff back volume volumes by upof water to 74 that percent. cause erty. More than 100 homeowners installed these GSI fea- showed that levels of water pollutants like raingarden gardens divertor stormwater about 15,000 gallons cistern that wouldon havetheir In additiondamage to toholding downstream back volumescreeks, the of projectwater thatalso helpedcause tures during RainWise’s first two years. Collectively these lead,to clean copper, the stormwater. and Monitoring zinc were showed reduced that levels by of overflowedproperty.rain gardens andOn collect average,divert more about than rebates15,000 one gallonsmillion cover gallons that 88wouldof have damage to downstream creeks, the project also helped stormwater that would have run off. Currently the pro- to cleanuppollutants tothe 90 stormwater. like percent. lead, copper, Monitoring and zinc showed were reduced that levels by upof percentoverflowed of project and collect costs. more The than first one millionphase gallons of to 90 percent. gram stormwateris active in Ballard that would and will have soon run be off.offered Currently in the the pro- pollutants like lead, copper, and zinc were reduced by up neighborhoodswas focused of Delridge,in Ballard Montlake, to help and reduce the area north sew-- to 90 percent. east ofgram the University is active of in Washington. Ballard and will soon be offered in the ageneighborhoods overflows. of Delridge, Montlake, and the area north- east of the University of Washington. 3 20042004 - //Broadview Neighborhood + Pinehurst Green Green Grids Grids The Broadview and Pinehurst Green Grids 2011 - Ballard2010 Roadside// Ballard Raingarden CSO Pilot Pilot 6 3 2004Seattle - Broadview took another + giant Pinehurst step forward Green in its GSIGrids Program 4 demonstratedby constructing the how Broadview GSI could Green beGrid appliedto collect SeattleSeattle completed 2011 completed - its Ballard first GSI its Roadside project first in roadside Raingardenthe right-of-way GSI Pilot 6 Seattleatstormwater tooka large another from scale giantacross acrossstep 32 forwardacres. a Theneighborhood. in itsproject GSI Program demon- designedproject to reducedesigned combined to sewer reduce overflows insewage 2011. In- strated how GSI could be applied at a large scale and 4 by constructingThe Pinehurst the GreenBroadview Grid Green reduced Grid to annual collect formationSeattle gathered completed through its this first pilot project GSI project in Ballard in has the right-of-way was followed in 2005 by the Pinehurst Green Grid which beenoverflows incorporated in into the2011. approach Information that will be used gatheredfor stormwater from across 32 acres. The project demon- designed to reduce combined sewer overflows in 2011. In- runoffhas shown volume the ability by to reduce 82 percent, runoff by 82 managing percent each futurethrough GSI work this for pilot sewer is overflowinforming reduction. every aspect The pilot strated how GSI could be applied at a large scale and formation gathered through this pilot project in Ballard has 9.7year million and manage gallons 9.7 million of stormwater gallons of stormwater annually, across hasof informed future all roadside aspects of projectGSI work. delivery including geo- was followed49 acres. in 2005 by the Pinehurst Green Grid which tech analysis,been incorporated siting, design, into construction the approach and community that will be used for has shownacross the 49 ability acres. to reduce runoff by 82 percent each engagement.future GSI work for sewer overflow reduction. The pilot year and manage 9.7 million gallons of stormwater across has informed all aspects of project delivery including geo- 49 acres. tech analysis, siting, design, construction and community engagement. 1 2 3 4 5 6

1 2 3 4 5 6 The Shift: SeattleGreen Green Stormwater Stormwater Infrastructure Infrastructure Program AccomplishmentsMayor McGinn’s March 6,201 2013 Executive3 2025 Goal:2025 Goal:Manage Implementation 700M gallons Breakdown Annually Order directed a significant shift in Seattle’s approach to stormwater management: 700M

To rely, whenever possible, on natural drainage I. POLICY + PROGRAM DEVELOPMENTsystems and green stormwater infrastructure (GSI).

This shift provides the opportunity to leverage our II. PUBLIC RIGHT-OF-WAYdrainage RETROFITS infrastructure investments to achieve 600M multiple benefits that improve water quality while furthering related urban sustainability goals like III. PARTNERSHIPS climate neutrality and adaptation, tree canopy recovery, and pedestrian/bicycle safety.

500M I. Policy + Program DevelopmentThe Order: • Establishes GSI as a critical aspect of a sustainable urban drainage system • Sets a 2025 implementation goal for GSI in Seattle Pre-vetted Concept Designs •for Directs Right-of-Way City departments to begin work on an implementation plan to achieve the goal 400M SPU, SDOT, DPD and King County planning, design, construc- The Goal: tion, and maintenance staff developedBy the year a set2025, Seattleof standard will be managing GSI 700M gallons of stormwater annually with green concept designs and details to usestormwater on residential infrastructure: rainstreet gardens, projects, roadside 300M swales, green roofs, pervious pavement, stormwater Seattle Public Utilities Capital Improvements resolving policy questions for futurecisterns, public rainwater projects. harvesting and reuse. Stormwater and Land Use Code Projects

By “stormwater” we refer specifically to the runoff gallons of stormwater managed annually by GSI Voluntary Projects: City-incentived 2025 Implementation Target generated when rain falls on impervious surfaces 200M like roads and roofs. Voluntary Projects: Partner-led

In July 2013, City Council unanimouslyThis goal ispassed a six-fold increase Resolution over current practice To Be Determined and, considering the projected population for 31549, which defines GSI as a criticalSeattle in aspect2025 (approaching of a 700,000sustainable people), means managing 1000 “greened gallons” per 100M drainage system and states it shouldresident be annually used with to natural manage drainage approaches runoff whenever possible. It also sets a bynew 2025. implementation target to manage 700 million gallons of runoffA six-foot annually square raingarden with managesGSI by 1000 2025 gallons of stormwater annually (generated from approxi- and directs departments to collaboratemately 70on sq. ft.an of imperviousImplementation surface). GSI Work Began We Are Here Goal 2001 2013 2025 Strategy. Currently, GSI manages 100 million gallons annually. GSI Manuals: Options Analysis + Design The first two volumes of a City of Seattle-King County joint GSI Manual were drafted in 2013.The manual will serve as the “go-to” resource for designers and project managers developing GSI for City of Seattle right-of-ways. The first two volumes cover topics related to determining project location and developing designs. Integrated Plan - Natural Drainage Systems (NDS) Partnering A proposal to use GSI to remove pollutants from residential roadway runoff within Seattle creek watersheds is part of SPU’s Integrated Plan submittal to EPA. The option, called “NDS Partnering,” outlines an approach for working with community groups and agencies to prioritize project locations to achieve multiple City and community goals. The submittal included a desktop-GIS analysis to establish Citywide technical feasibility maps for GSI facilities on private property and in the public right-of-way. This approach will be further developed in 2014. Responsive Community Engagement IN DELRIDGE, project outreach engaged a diverse com- IN BALLARD, project outreach responded to concerns munity with the help of neighbohrood-based organizations: about the 2010 Ballard Pilot Project:

• Multi-lingual “Project Ambassadors” went door-to- • A survey was sent to all residents in the neigh- door to introduce the project and answer questions borhood to collect local knowledge about drainage issues and to understand community questions • A survey, additional door-to-door outreach, and an open house gathered residents’ input on location • Two open houses were held to keep the community engaged in the process to select project blocks • A “Walk and Talk” event and an additional open house were held to get input on proposed locations • A community liaison reached out to neighbors door- and early designs. to-door and a “Walk and Talk” event gathered residents’ input on proposed locations and early designs.

July 2013 Open House -- Delridge Natural Drainage Project II. Public Right-of-Way Retrofits Swale on Yale (Capitol Hill Water Quality Project) This project will improve water quality in Lake Union by removing about 65 percent of total suspended solids (TSS). In 2013, the project completed construction of GSI systems on two blocks: Yale Ave. N. and Pontious Ave. N. The two swales will manage about 36 million gallons of stormwater annually. Ballard Natural Drainage for CSO Control This project will help to reduce sewage overflows into Salmon Bay in Ballard. In 2013, the project team identified 22 blocks for roadside raingardens. This phase involved geotechnical evaluation to find soils that drain well and significant outreach and engagment with residents in the project area. Venema Natural Drainage for Creek Water Quality This project will improve water quality in Venema Creek and improve stormwater conveyance in the surrounding neighborhood. In 2013, the project team determined specific locations and reached 60 percent design. Delridge Natural Drainage & Neighborhood Greenway This project will reduce sewage overflows into Longfellow Creek and support SDOT efforts to provide people of all ages and abilities with safe and inviting places to walk and ride bicycles. In 2013, the joint SPU-SDOT project team identified the route for a Neighborhood Greenway on 21st and 17th Ave. SW and identified blocks for natural drainage systems along 17th Ave. SW. King County // Barton Natural Drainage for CSO Control This King County Wastewater Treatment Division (WTD) project to construct natural drainage Swale on Yale systems along 15 blocks in the Westwood/Sunrise Heights neighborhood will reduce sewage Under Construction overflows into Puget Sound. The project completed design in 2013.

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Residential RainWise Intallations

RainWise Raingarden in Ballard Program Workplan 2014-2015

I. POLICY + PROGRAM DEVELOPMENT Community Clean Trees II. PUBLIC RIGHT-OF-WAY PROJECTS Water III. PARTNERSHIPS

Beautiful I. Policy + Program Development Nearby Nature Streets 2025 GSI Implementation Strategy You! The 2025 GSI Implentation Strategy initiated by Resolution 31549 is slated for delivery in June 2014. Strategy implementation will continue throughout 2014-2015. Healthy Energy Pre-vetted Concept Designs for Private Development Safety Habitat Savings Building on the 2013 interdepartmental effort, GSI concepts and details developed for public projects will be considered for pre-approval for private development projects and inclusion in the Right-of-Way Improvement Manual.

RainWise In 2014, RainWise will expand to include green roofs and permeable pavement. To improve access and equity, the program will evaluate options for citywide eligibility. Currently only property owners in sewage overflow areas are eligible. Options to eliminate up-front homeowner costs are being explored to reduce the barriers to participation in lower income neighborhoods. The program will also pilot methods for more effective outreach to historically underserved communities. Code Updates A two-year city-wide process to review and revise land-use codes to 1) minimize impervious surfaces 2) reduce stormwater runoff and 3) preserve native vegetation was initiated in 2013 and will be completed by June 2015. The Stormwater Code updates for on-site stormwater management will build on the current “GSI to the maximum extent feasible” requirement and will align Seattle regulations with State requirements. This update will also be adopted in 2015. Third Party Inspections In 2014, third-party inspection requirements for GSI installations in the public right-of-way will begin. This will ensure mini- mum standards of quality and will support cost-effective operations and maintenance of the facility over time. GSI Manuals Construction and Operations & Maintenance volumes will be written iin 2014.

II. Public Right-of-Way Projects Ballard, Delridge & Venema Natural Drainage Projects The Ballard and Delridge projects will be designed during 2014 and are slated for construction in 2015. There will be on-going opportunities for community input and engagement throughout the design process. The Venema Natural Drainage Project will begin construction in 2014. King County Natural Drainage Projects Construction of the Barton Project begins in early 2014 will continue through 2015. The County will also complete planning and begin design for South Park and Highland Park GSI projects in 2014 and will begin early scoping for projects in the University Basin (Green- lake area) and Montlake Basin (Madison Park/Garfield area).

III. Partnerships Natural Drainage Systems (NDS) Partnering In 2014, the GSI Program will develop a system to accept requests for GSI projects on residential streets, in areas where it is technically possible. The approach will focus on community partnerships to achieve critical water quality goals as well as community goals such as improved pedestrian mobility and tree canopy recovery. Voluntary Raingarden Client Assistance Memo The Voluntary Roadside Rain Garden CAM (client assistance memo) was revised and finalized to support community groups’ efforts to build neighborhood-driven GSI projects in the public right-of-way.