Session Title

Utilizing Green Infrastructure to improve Water Quality and Environmental Outcomes in the Urban Realm

Conference Track

Protection, Remediation and Restoration

Conference Name

Salish Sea Ecosystem Conference (2016 : Vancouver, B.C.)

Contributing Repository

Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.

Type of Presentation

Oral

Abstract

In 2009 King County Wastewater Treatment Division (KCWTD) selected green stormwater infrastructure (GSI) as the preferred alternative for controlling combined sewer overflows (CSO) for the 1100-acre Barton combined sewer system (CSS) basin in Seattle. In 2008 KCWTD reported that the basin had an average of four overflows per year that discharge a total of four million gallons into Puget Sound. In order to reduce the overflows to no more than one CSO event per year for Washington State’s Department of Ecology compliance, KCWTD retrofitted 15 residential streets with bioretention cells in order to intercept, treat and reduce the amount of stormwater discharging into the CSS. After filtering through the bioretention soil and plantings, stormwater discharges into an underdrain that conveys the flows into an underground injection control screen well for deep infiltration to a receptive soil layer beneath the area’s glacial till. Intercepting stormwater before it enters the CSS will reduce KCWTD’s annual treatment plant costs. The project completed construction of the first ten streets in 2014 and the remaining five streets in 2015. Our presentation will cover challenges confronted by this pioneering project (the first for KCWTD) from planning, design, community outreach, construction and through the first two years of operations and maintenance. We will also review how we balanced CSO control performance with community concerns and street performance so issues such as slope, planter width, existing utilities and trees, access, and on-street parking patterns were key design drivers; how KCWTD developed and implemented a new maintenance program for the wastewater treatment division; and how the team developed infrastructure that met current needs while incorporating flexibility to respond to an uncertain future and changing climate. Finally, we will provide the latest results in monitoring for CSO events in the basin for the first two years of operation and maintenance.

Comments

http://www.kingcounty.gov/environment/wtd/Construction/Seattle/BartonCSO-GSI.aspx

2_SW3F_GwilymSalish Sea 4-13-2016.pdf (12046 kB)
PPT re. Barton CSO Control Project with Green Stormwater Infrastructure, presented by Kathryn Gwilym, MIG SvR

2_SW3F_GwilymSalish Sea 4-13-2016.pdf (12046 kB)
2nd Try to upload pdf of ppt

Rights

This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.

Language

English

Format

application/pdf

Type

Text

Share

COinS
 

Protecting Puget Sound from CSOs by retrofitting Urban Neighborhoods with Green Stormwater Infrastructure

2016SSEC

In 2009 King County Wastewater Treatment Division (KCWTD) selected green stormwater infrastructure (GSI) as the preferred alternative for controlling combined sewer overflows (CSO) for the 1100-acre Barton combined sewer system (CSS) basin in Seattle. In 2008 KCWTD reported that the basin had an average of four overflows per year that discharge a total of four million gallons into Puget Sound. In order to reduce the overflows to no more than one CSO event per year for Washington State’s Department of Ecology compliance, KCWTD retrofitted 15 residential streets with bioretention cells in order to intercept, treat and reduce the amount of stormwater discharging into the CSS. After filtering through the bioretention soil and plantings, stormwater discharges into an underdrain that conveys the flows into an underground injection control screen well for deep infiltration to a receptive soil layer beneath the area’s glacial till. Intercepting stormwater before it enters the CSS will reduce KCWTD’s annual treatment plant costs. The project completed construction of the first ten streets in 2014 and the remaining five streets in 2015. Our presentation will cover challenges confronted by this pioneering project (the first for KCWTD) from planning, design, community outreach, construction and through the first two years of operations and maintenance. We will also review how we balanced CSO control performance with community concerns and street performance so issues such as slope, planter width, existing utilities and trees, access, and on-street parking patterns were key design drivers; how KCWTD developed and implemented a new maintenance program for the wastewater treatment division; and how the team developed infrastructure that met current needs while incorporating flexibility to respond to an uncertain future and changing climate. Finally, we will provide the latest results in monitoring for CSO events in the basin for the first two years of operation and maintenance.