Boring Machine Receiving Pit and Storm Line Tie-in
King County, Department of Public Works
Renton, Washington

• The goals of this project were twofold:

  - First, to provide a stable, dry excavation through which a 4-foot boring machine could exit.

  - Second, to provide shoring that would enable tie-in of a 4-foot-diameter storm line into an existing 11-foot-diameter pipe.

• Frozen soil shoring was created around and below many existing untilities, including an 11-foot-diameter concrete pipe.

• Soils were wet loose sand and silt. The frozen soil shoring extended deep below the 26-foot-deep excavation bottom to cut off most groundwater inflow.