Update on Barton Sewer Overflow Green Infrastructure

King County’s Wastewater Division is working in West Seattle to upgrade two pump stations. Work on the Barton Pump Station includes installing green infrastructure in several West Seattle neighborhoods up-water from the station.

Sunrise Heights and Westwood neighbors will have seen King County Wastewater Division crews doing field investigations throughout the fall. This is necessary field work to understand the characteristics of Sunrise Heights and Westwood neighborhoods and begin the process of selecting sites for the bioretention swales.

To learn more about the project visit the Barton CSO web page: www.kingcounty.gov/environment/wtd/Construction/Seattle/BartonCSO-GSI

Check out the Barton CSO Project Field Work video!: http://www.kingcounty.gov/environment/wtd/Construction/Seattle/BartonCSO-GSI/Video.aspx

The Barton Combined Sewer Overflow (CSO) Control project team has been conducting ongoing field investigations since early September.

What have they learned:

Field work to date indicates that soils do not infiltrate well consistently across the project area at shallow depths (0-20 feet) although there is a larger, deeper soil layer called Vashon Advance Outwash that does infiltrate well. Field work will continue through mid-January to further examine the Vashon Advance Outwash soil layer to understand what happens to water once it has infiltrated into this layer and the relationship to the regional water table (aquifer). The project team’s goal is to site bioretention swales in the best possible location for intercepting stormwater runoff from the street and providing CSO control. The information gathered from the geotechnical testing will ultimately be used to design the bioretention swale system and determine the design for infiltrating into the Vashon Advance Outwash soil layer.

Next Steps

The project team will continue to survey streets within the project area, sample groundwater and collect and monitor data from the installed wells.

The data gathered from the field investigations will be plugged into a computer model of the project area. This model will be used to help the team determine the number of bioretention swales that will be needed to control overflows into Puget Sound from the Barton Pump Station.

Community meeting will held in early 2012 to share results of field work and discuss the locations and approach to the design of bioretention swales.

Block level outreach and design workshops will be scheduled with neighbors on streets selected for bioretention swales.

For more information contact Kristine Cramer at 206-263- 3184 or kristine.cramer@kingcounty.gov, visit the Barton CSO web page at www.kingcounty.gov/environment/wtd/Construction/Seattle/BartonCSO-GSI, or watch the Barton CSO Project Field Work video at http://www.kingcounty.gov/environment/wtd/Construction/Seattle/BartonCSO-GSI/Video.aspx