South Magnolia CSO Control Project
October 17, 2014 Update -
King County's drilling contractor, Mears Group, Inc, is continuing underground drilling of the pilot bore for the new gravity sewer pipeline at both 32nd Avenue West and 23rd Avenue West. For more detail on Horizontal Directional Drilling, visit www.mears.net/horizontal-directional-drilling/index.php/hdd/the-hdd-process
In the coming week, crews will begin the “reaming process” to enlarge the bore hole to the final size of the sewer pipe. Work will include many of the same activities that were used during drilling of the pilot bore. King County is continuing to monitor both noise and vibration to ensure that levels are within specified limits. Pipe delivery and assembly will begin on 32nd Avenue West above 33rd Avenue West in the coming weeks.
What you can expect
• Work hours Monday through Friday, 7 a.m. to 7 p.m.; Saturdays, 9 a.m. to 5 p.m.; crews may work longer on some days to complete drilling tasks that must be finished that day, but they will not exceed the allowed City of Seattle hours.
• Increased truck traffic, crews on site, heavy construction activity, noise and some vibration near the work area.
• Crew members at the site after hours and on Sundays to check site security and operating equipment.
Latest construction update: Construction activities on 32nd Ave W (PDF, October 17, 2014)
Excavation at the CSO storage facility site in the Smith Cove area is also continuing.
Drilling operations are underway on 32nd. Please drive slowly though the temporary detour and construction area.
View the Fall 2014 Newsletter (PDF, September 2014)
Construction photos: gravity sewer pipeline and storage tank
South Magnolia CSO basin project area
How will the new CSO facility work? View animation.
South Magnolia basin and project location.
Young bald eagles appear larger and darker than their white-headed parents.
King County is constructing a new combined sewer overflow (CSO) control facility in Magnolia. A 1.5-million gallon underground tank will temporarily store excess flows of stormwater and sewage when heavy rains fill pipes, reducing untreated overflows to Puget Sound. A second component of this facility is a new 3,000-foot gravity sewer pipeline installed from 32nd Avenue West below Magnolia Bluff that will transfer excess flows to the new CSO control facility on 23rd Avenue West in the Smith Cove area.
On 32nd Avenue West, construction crews will install the new gravity sewer pipeline that will be drilled under the hill to the Smith Cove Athletic Field to connect to the underground storage tank on 23rd Avenue West. See map on right.
Why does King County need to do this project?
This project is part of a long-term King County plan to help protect Puget Sound and control combined sewer overflows (CSOs) in local waterways. When completed, the project will meet current Washington Department of Ecology requirements of no more than one CSO discharge per year on a long-term average. The project is included in a federal consent decree that requires completion by December 2015.
What is the schedule for this project?
Planning and design for this project took place from 2007 to 2013. Construction began in 2014 and is scheduled for completion in 2015.
View South Magnolia CSO Control Project Timeline (PDF), updated May 2013.
Being a good neighbor to nearby Magnolia eagles
Magnolia Boulevard Park has a pair of bald eagles that have resided in a cottonwood tree above 32nd Avenue West for several years. During project design and as construction approached on 32nd, Hillary Schafer, King County’s Environmental Planner, worked closely with local and federal environmental agencies to develop plans for work around the eagle nests. Plans in place include seasonal restrictions on certain activities during mating seasons, monitoring and other accommodations for the birds. For more information, view the Fall 2014 Newsletter (PDF) or contact Hillary.Schafer@kingcounty.gov.