Port Mann Retaining Wall

Project Description

Approximate Shoring Contract Value: $750,000
Engineer: Worley Parsons
SWC Site Supervisor: Sean Buchholz

SCOPE OF WORK

Secant Piles with 23ea. HP 310×125 steel beams
13 – 30m anchors: 6-strand DCP

PROJECT DESCRIPTION

A pig launcher is being installed at the Port Mann Station by Fortis BC to facilitate mechanical cleaning and inspection of existing NPS 36 Fraser River pipeline. The location of the pigging station is in the area of a large slope, part of which needed to be removed. The Project invovled the installation of a retaining wall for the stabilization of the slope, and was designed to resist seismic forces.

Originally, the wall was designed as a jet grout and steel pile retaining wall, with a whaler beam and ground anchors. Due to very limited working space (the transmission lines had been daylighted prior to start of work) and a lack of potable water, SWC made a proposal to replace the jet grouting with secant piles, to be installed by Henry Drilling Foundation (HDF).

As HDF began secant pile installation, boulders were encountered, which had not been shown in the borehole logs. This unexpected ground condition would have made it nearly impossible to obtain a consistent jet-grout wall.

This project was schedule-driven, and as the unforeseen boulders set back the schedule, SWC worked long hours and was able to finalize the project within budget and on time.