Top Projects of 2002 -- Seattle DJC.COM

#3. Henderson/Martin Luther
King Jr. CSO project

Original contract amount: $41,759,995

The tunnel outlet regulator will control the release of CSO flows through the south end of the new 3,100-foot storage and treatment tunnel.
Image courtesy of King County

Project address:
South Henderson Street, 42nd Avenue South and South Norfolk Street in the Rainier Beach area of Seattle

Start of construction:
July 15, 2002 (notice to proceed)

Expected completion date:
December 2004

Owner:
King County

Description The Henderson/Martin Luther King Jr. CSO project aims to cut the number of overflows into Lake Washington during heavy storms. During severe storms, the 50-year-old Rainier Beach sewer exceeds capacity between 15 and 30 times, amounting to an estimated 30 million-60 million gallons of combined wastewater and storm water flowing into Lake Washington every year.

The CSO project will reduce overflows by adding storage capacity to the system and enhancing treatment capabilities. The new system will be capable of providing primary sewage treatment for extreme storm occurrences and overloads before discharge at the Norfolk outfall to the Duwamish River.

The main components include a 3,100-foot storage and treatment tunnel with a 14-foot-8-inch inside diameter. The tunnel will run along 42nd Avenue South, parallel to Martin Luther King Jr. Way. The concrete-lined tunnel will be constructed 30-100 feet underground, mostly through clay, with sections through outwash deposits of sand and gravel, and will drain by gravity rather than utilizing a pump station.

After storms, the tunnel will convey stored flows to the current King County treatment facilities at Renton and West Point.

An inlet regulator will flank the storage and treatment tunnel on the north end at Fairbanks Street and the tunnel will have an outlet regulator at the intersection with Norfolk Street on the south end. The inlet regulator will have a sodium hypochlorite storage and feed system, sluice and slide gates, and activated carbon foul air scrubbers.

The outlet regulator will incorporate hydraulically actuated bar screeners, sluice and slide gates, a biosulfite feed and storage system, electrical and instrumentation systems, and pile-supported bridge structures.

Additional project components include sewer pipeline and force main with open cut construction and tunneling under Interstate 5 and adjacent railroad tracks.

King County Department of Natural Resources & Parks manages this project in cooperation with Seattle Public Utilities. The project is funded by a low-interest loan from the state Department of Ecology.

PROJECT PARTICIPANTS

Contractor:
Tri-State Construction, P.O. Box 3686, Bellevue, WA 98009-3686, (425) 455-2570

Engineer:
HDR Engineering, 500 108th Ave. N.E., Suite 1200, Bellevue, WA 98004-5500, (425) 453-1523

Other Participants

Adolfsen

Fortner Trucking

Gary Struthers & Associates

Ground Support

Harbor Pacific

Hayward-Baker

Hurlen Construction

Jacobs Engineering

Lakeside Industries

NCA Engineers

Northwest Boring/Kenny JV

Pac Rim Geotechnical

P&G Landscape

Salinas Construction

Shannon & Wilson

Streeter & Associates

SvR Design Co.

White Shield