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Wastewater Treatment

King County, Washington

For questions about the Wastewater Treatment Division website, please send an e-mail message or contact us at:

King Street Center
201 S. Jackson St., Suite 500
Seattle, WA 98104-3855
Phone: 206-477-5371
Fax: 206-684-1741
Telecommunication device for the deaf (TTY): 711

Get Directions to our office location in Seattle, Washington.

Staff Contacts

Barton CSO Control Project


Construction of the bioretention swales (roadside rain gardens) will occur in phases, with preparation work beginning in July 2013 and major street construction occurring over two seasons in 2014 and 2015.

2015 street schedule for construction

March 2015 Update -- weekly construction updates will be posted on the project home page.

2015 street construction schedule (view 2014 schedule)

 2015 street construction schedule and map



Block updates (to be posted)

7300 block 32nd Ave SW

7300 block 30th Ave SW

7500 block 32nd Ave SW

8100 block 31st Ave SW

8600 block 31st Ave SW

2014 street construction schedule 

Planned construction sequence in 2014 (revised June 2014)
Barton CSO Control Project area


Block Updates

#1, 7300 block 34th Ave SW

#2, 7500 block 34th Ave SW

#3, 7900 block 34th Ave SW

#4, 7300 block 31st Ave SW

#5, 7500 block 31st Ave SW

#6, 7700 block 31st Ave SW

#7, 7900 block 31st Ave SW

#8, SW Kenyon St, between 34th Ave SW and 32nd Ave SW

#9, 8400 block 34th Ave SW
(Year 2 block moved to 2014)

#10, 8600 block 34th Ave SW
(Year 2 block moved to 2014) 

Year 2 street notifications

Fall 2013 – Winter 2014: Tree transplant and well drilling

Starting in October, trees scheduled for transplant to private property owners will be dug up, balled and put in a burlap sack in front of the property for transplant. Homeowners will be notified in advance of transplant work and are responsible for transplanting tree to their yard. Trees scheduled for transplant to a new location in public right-of-way will be replanted by the tree crews.

Between January and May 2014, crews will drill the wells that will carry stormwater deep underground on all 15 blocks.

Landscape crews will dig up trees and prep them for transplant to private property or a new location in the public right-of-way.
Landscape crews will dig up trees and prep them for transplant to private property or a new location in the public right-of-way.
  Well construction uses drill rigs and heavy trucks similar to those used for the 2011 geotechnical field work
Well construction uses drill rigs and heavy trucks similar to those used for the 2011 geotechnical field work.

Spring 2014 – Fall 2015: Roadside rain garden construction

Street construction will occur in phases, with half of the streets scheduled to be built in 2014 and the other half in 2015. Once the contractor is on board in fall 2013, a detailed street schedule will be developed and shared with the community. Heavy construction is expected to take about two months per street. Once plants are established and the swale system has been tested for infiltration, stormwater will be allowed to flow in. Final street restoration (permanent paving) occurs at the end of construction.

Street construction includes five major activities:

  • Demolition of existing planter strip
  • Installation of pipes, bioretention soil, and vegetation
  • Restoration of curb, street, and existing landscaping as needed
  • Plant establishment (approximately two months)
  • Flow testing and system commissioning

Seattle streets under construction

How roadside rain gardens will change over time

Roadside rain gardens change over time as plants mature and become well-established. 

How swales will change over time -- two examples of Seattle-area bioretention systems
View larger version

Construction update (February 2015)

2015 construction season to begin first week of March. Road side rain gardens to be constructed on five blocks.

View project update (PDF, February 10, 2015).

We will continue to notify neighbors in advance of construction work, post a weekly web update to the Barton CSO Control project web page, and post street by street notifications (on this page).

We will also maintain a 24-hour project hotline during active construction through 2015: 206-205-9184.

What you can expect during construction

  • Bioretention swales constructed in two seasons – March to October 2014 and March to October 2015
  • Each block will take approximately two months to complete
  • Work hours in compliance with City of Seattle permits, which typically allow work between 7 am and 6 pm Monday to Friday
  • Local access at all times for homeowners and emergency vehicles
  • Pedestrian access at all times
  • Restricted parking while street is in construction
January 2014 Project update
Approximate construction timeline for typical street
 (January 2014 Project Update).

For more information