Underground Challenges on the Wilburton Sewer Project: Complex Design Elements are Put to the Test During Construction

摘要

This paper discusses the construction of two unique design elements for the City of Bellevue Wilburton Sewer project that were presented at the 2015 ASCE Pipelines conference. The project included 4,300 feet of new 12-inch to 30-inch diameter sewer, with an alignment traversing a peat bog, creek, ten lanes of Interstate 405 (I-405), a Lexus car dealership, a major arterial, and a retaining wall along I-405. These challenging site and soil constraints were navigated by a wide range of design solutions and technologies, including: supporting the pipe on auger cast piles, backfilling the pipe with geofoam, prescribing specialized shoring systems, crossing under the arterial using trenchless technology, CIPP rehabilitation of an existing pipeline, and complex bypass pumping arrangements. This paper focuses on the significant underground risks associated with the installation of the auger-cast piles through the peat bog and the deep trenchless guided bore crossing across Main Street, and summarizes the effectiveness of these design solutions during construction for this complex sewer replacement project in Bellevue, Washington.