June 1, 1998
Two projects to begin on Tolt River
by Jane McClure
Seattle Public Utilities is beginning two major construction projects on the Tolt River water supply system. One, a new water treatment facility, will be built on 460 acres along Tolt Pipeline Road, just north of the confluence of the north and south forks of theTolt River. Construction on the project is scheduled to start this month and continue for approximately 30 months, according to Darrell Fallstrom of Dillingham construction. Site preparation is expected to be completed in October, with concrete construction scheduled for the following 18 months.
Fallstrom said normal construction hours would be observed, including the possibility of 10-hour days, with minimal work scheduled for evenings and weekends. Peak construction traffic is estimated to be 100 round trips to the site per day, with concrete trucks running every 10-15 minutes during morning hours. From SR-203, construction traffic will be rerouted onto Stillwater Hill Road to reach the right-of-way off Kelly Road.
Seattle Public Utilities engineer Elizabeth Kelly encouraged residents to call 206-386-9779 if they observe unsafe driving practices related to the construction. Kelly also said Tolt Pipeline Road occasionally may be closed to recreational use by the public. Information will be posted at a notice board located at the intersection of the right-of-way and Kelly Road. Other posting sites and establishment of an information hotline are being considered.
Another project scheduled to begin this summer is construction of Tolt Pipeline No. 2, which provides a second water supply pipeline across the Snoqualmie Valley. Phases two and three of this 24-month project include eight miles of pipeline from Redmond to 1500 feet east of SR-203 between NE 124th St. and Big Rock Road south of Duvall. Major aspects of this project involve open trenching into which the welded steel pipe, ranging in diameter from 60-81 inches, will be laid, and tunneling under sections of the Snoquamie River and Bear Creek.
Pipeline crossing SR-203 and West Snoqualmie Road will be installed using a jack and bore process that will not require cutting into the roadways. Stephanie Murphy, who is managing this project for Seattle Public Utilities, said installation will require the westbound lane of Novelty Hill Road to close at times, although not during peak traffic hours. Pipe haulers coming from Portland may use either SR-203 or Novelty Hill Road via Avondale. Backfill may be hauled from either Monroe or Issaquah.
Staff say establishment of a second pipeline will increase reliability of the Tolt water supply system, and that the large pipe will allow delivery of the new treatment facility's 120 million gallons per day capacity. New pipeline is already being installed from the site of the new filtration plant east toward the reservoir. Groundbreaking for the water treatment plant, which is expected to be operational by December, 2000, will be held in mid-July of this year. The facility will continue to provide 120 million gallons per day, or approximately one-third of Seattle's water supply. The plant will offer ozonation, flocculation and a new filtration process that will enable the reservoir to operate even when the river is muddy.
CDM PHILIP consortium, a Washington-based joint venture company, is responsible for the design, construction and operations of the facility. The company has contracted with the city for $65 million to design and construct the facility, and another $36 million to operate the facility for 25 years.