Portage Bay 138 Gate Retrofit & Pump Station 20 Improvement Project

Photo of Portage Bay from street end of E Shelby St.
This project will improve water quality in the northern part of South Park.

Project Description

Improving Service Reliability in Your Neighborhood
Portage Bay 138 is a combined sewer basin, where combined sewage and stormwater flows to Pump Station 20 at the street end of E Shelby St and is pumped to a treatment plant.

During heavy rain events, high volumes of stormwater can overwhelm the sewer system causing a combined sewage overflow (CSO) into Portage Bay. The combined mixture of raw sewage and polluted stormwater can be harmful to humans, aquatic life, and other wildlife.
 
For this project, Seattle Public Utilities (SPU) will be modernizing the way our existing infrastructure manages high flows during rainstorms. To accomplish this, SPU will remove the existing flow restriction device attached to the buried storage tanks beneath the northern sidewalk on E Shelby St and replace it with an automated gate. This will allow SPU to optimally manage flows in the storage tanks in real time.
 
SPU is also making improvements to Pump Station 20, which is also located at the street end of E Shelby St, to help us continue to provide reliable sewer services to the community.
 
Because of the proximity of the work on Pump Station 20 to the Portage Bay Gate Retrofit project and the above-ground impacts, SPU will perform this work at the same time. This will help reduce the duration of construction in the area and other construction impacts on the community as well as minimize restoration costs.

Location

Construction will take place at the street end of E Shelby Street near Fuhrman Ave E and Boyer Ave E (link to project area map).  

What & Why

Portage Bay 138 is a combined sewer basin, where combined sewage and stormwater flows to Pump Station 20 at the street end of E Shelby St and is pumped to a treatment plant.

During heavy rain events, high volumes of stormwater can overwhelm the sewer system causing a combined sewage overflow (CSO) into Portage Bay. The combined mixture of raw sewage and polluted stormwater can be harmful to humans, aquatic life, and other wildlife.

For this project, Seattle Public Utilities (SPU) will be modernizing the way our existing infrastructure manages high flows during rainstorms. To accomplish this, SPU will remove the existing flow restriction device attached to the buried storage tanks beneath the northern sidewalk on E Shelby St and replace it with an automated gate. This will allow SPU to optimally manage flows in the storage tanks in real time.

SPU is also making improvements to Pump Station 20, which is also located at the street end of E Shelby St, to help us continue to provide reliable sewer services to the community.

Because of the proximity of the work on Pump Station 20 to the Portage Bay Gate Retrofit project and the above-ground impacts, SPU will perform this work at the same time. This will help reduce the duration of construction in the area and other construction impacts on the community as well as minimize restoration costs.

What's Happening Now?

The contractor has completed the gate retrofit work, pavement restoration at the street end of E Shelby St, and improvements on the pump station.

We have worked with Seattle City Light to install permanent power at the pump station and SPU crews are preparing to begin the pump station commissioning process. This includes a test of all equipment, followed by a seven-day operational test.

Once the test is finished and we have confirmation that the pump station is fully operational, our contractor will remove the temporary bypass system, perform any final restoration work at the site, and demobilize from E Shelby St.

Construction on this project is still on track to be completed this fall.

Some construction activities will have impacts to street end access and may block driveways during working hours. We cannot guarantee the timely flagging of residents in and out of the driveway between 8 a.m. and 4 p.m. when crews are working, but the contractor will provide driveway access whenever it is safe and feasible.

Please sign-up for the project email list to receive updates throughout construction.

Community Benefits

The Portage Bay 138 Gate Retrofit & Pump Station 20 Improvement Project will improve water quality and public health by reducing the number of CSOs into Portage Bay. This work will reduce the risk of pump station failure and maintain safe working conditions for SPU crews within the pump station, in addition to helping SPU comply with industry standards and regulations.

Construction Impacts

We understand that this project is highly impactful, and our team worked to find solutions and ease the stress of construction.

During the remainder of construction, you can expect:

  • Most of the construction will occur within the pump station
  • Construction noise, dirt, dust, and vibrations
  • Construction traffic and staging of materials in the area
  • Brief, intermittent vehicle access restrictions during working hours
    • Activities requiring 24-hr access restrictions have been completed. You will receive additional notice in the unlikely event additional closures night or weekend closures are needed.
  • On-street parking near the project area on E Shelby St will continue to be restricted
  • Pedestrian access to homes will be maintained

Community Engagement

Please subscribe to the project email list to receive up-to-date information throughout construction.

Schedule

high level chart illustrations of project timeline milestones

Schedule is subject to change due to weather and other factors

Chart text:

  • Task "Construction and Mobilization Bypass" represents March - mid May
  • Task "Gate Retrofit" mid-May through early July
  • Task "Pump Station" spans July through October
  • Task "Restoration and Demobilization" from nearly mid-October through December

Early 2019

  • Project design continues
  • Engagement with the community

Late 2019

  • Finalize project design
  • Continue to engage the community

Early 2020

  • Pre-construction activities and community outreach including February 27 drop-in session from 4 to 6:30 p.m. at project site
  • Construction work begins in early March, and it is expected to take 7-9 months
  • Gate Retrofit work is tentatively scheduled for mid-May and take about 6-8 weeks. During this time, vehicles access to driveways on the north side of E Shelby St will be prohibited

Late 2020

  • Pavement restoration, which will close vehicle access to the street end for less than 1 week is scheduled to occur in late 2020
  • Construction scheduled for completion
  • Construction updates, as needed, via website and email lists

* Tentative schedule as of April 2020 and is subject to change due to weather or other factors.

Background

In some areas of the City of Seattle, sewage and stormwater runoff are collected in the same pipes, known as combined sewers. During heavy storm events, sometimes the flow in these pipes exceeds the sewer system capacity. 

When this occurs, the system overflows at an outfall structure designed for this purpose. This is called a combined sewer overflow (CSO). There are currently 84 outfalls in the City of Seattle where CSOs can occur.
 
To comply with State and Federal requirements, SPU must limit the number of CSOs at each outfall around the city of Seattle to an average of no more than one per year based on a 20-year moving average.
 
Portage Bay's basin 138 currently exceeds this standard at almost twice the required limit. The goal of this project is to reduce the number of CSOs in order to protect the environment and public health.
Following this work, SPU will continue to monitor performance and identify if additional action is needed to limit CSOs to less than 1 per year on average.