SEATTLE - INTERCEPTOR
OWNER: King Country
LOCATION: Seattle, WA
VALUE: $8.4 Million
Kenny Construction used its 132 inch diameter Lovat EPBM to mine in multiple modes on this difficult and challenging project for King County, Washington. The Joint Venture of Northwest Boring and Kenny served as a tunnel subcontractor for Tri-State Construction to install tunnel sections connecting the main relief sewer constructed by open cut methods.
Kenny began the project by installing two sections of 108 inch diameter tunnel by jacking pipe methods. The sections were 255 and 260 feet long. The EPBTBM was converted from the jack pipe configuration to a segment installation setup and then was installed to mine the main drive of 2,580 feet using a single pass 108 inch diameter bolted and gasketed segmental liner.
The drive was completed highly successfully with ground settlements about one half of the projected levels. Use of the EPB mode with screw conveyor and diligent grouting procedures were credited with the settlement success. Progress in the EPB mode and bolted gasketed segments exceeded all expectations in this complex geology consisting of low plasticity, clayey silts (40%) and silty sands(60%).
A maximum production of 16 rings in one shift was achieved with an average advance of 9 rings.