Tolt Pipeline Project

Owner
Seattle Public Utilities
Engineer
CH2M Hill Roger Beielen
General Contractor
Tri State Construction
Jacking Sub Contractor
Northwest Boring Construction, Inc., Woodinville, WA
Pipe Size

2,203 feet of 88″ O. D. Permalok Steel Casing

The Problem

Install 2203 feet of pipe to increase the drinking water capacity to Seattle. Tough topography requiring large diameter pipe and a steep uphill angle, was a major concern; and the project required pipe to cross the Snoqualmie River with an aqueduct extending approximately 25 miles to provide a larger quantity of drinking water for the Seattle area.

The Solution

Using Permalok Steel Casing, Northwest Boring Construction, Inc. was able to use a 90″ Soltau RVS 600 STS to install 2203 feet of 88″ O. D. The cutting edge microtunneling technology enabled the contractors to deal with the steep slopes and long drives to complete what is believed to be a United States record due to the volume of material excavated. The project won the Trenchless Technology 2002 Project of the Year Award for New Installation.

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