Chambers Creek Tunnel Rehabilitation, Access Shaft Design, Pierce County Public Works
The goal of this project was to preserve 3,500 feet of the existing 72-inch Chambers Creek sewer main. CivilTech’s tasks included supporting the contractor with construction of a temporary access shaft on Chambers Creek Road that is being used to gain entry into the existing interceptor tunnel so relining work can be done. Our engineers preformed design calculation review on the proposed corrugated steel liner plate and reinforcing rib waler for a 92-foot deep shaft. As part of the review, CivilTech performed independent calculations to compare against the original design, as well as reviewed drawings, boring logs, load calculations for the 7 gage x 16” wide liner plates, and load calculations for butt joint connections for steel ribs. CivilTech’s findings indicated that the proposed corrugated steel liner plates with reinforcing rib walers were designed in accordance with the required standards. CivilTech also prepared a monitoring/inspection/quality control plan for construction of the 92-foot deep shaft and performed construction observation and monitoring during installation of the shaft to verify proper compliance with the shoring plan. CivilTech also provided shoring designs, calculations and construction monitoring for an additional 71-foot deep soldier pile shaft. This shaft, located at station 34+75, allowed another access point for the jacking frame to slipline the existing sewer line.