Vancouver port expansion

Pennie has installed 76 km of underwater stone columns as part of the scheme to expand the Deltaport container terminal in Vancouver, Canada. The UK£ 3.6 million (US$ 5.9 million) densification contract at Canada's largest container port is part of a scheme to create a third birth for some 400000 Twenty-foot Equivalent Units (TEUs) for client Port Metro Vancouver (PMV).

Pennine's Simon Young said, "Because the port lies in an area with a high level of seismic activity, any construction needs to be protected against potential damage from earthquakes. Our job has therefore been to install stone columns to provide densification that will resist seismic loading in the event of an earthquake."

After conducting trials in 2007, Pennine was asked by main contractor Deltaport Constructors Ltd to complete the project in seven months. Achieving this meant working 20 hours a day, six days a week.

The Pennine used ten BD400 vibroflots - the most powerful in its range - and four HD150 vibroflots on the project, along with a flotilla of additional equipment including power packs, water jetting pumps and data acquisition systems. Using the wet top feed method, it installed over 5800 columns, all within a pre-excavated trench, backfilled with a coarse granite gravel, at varying depths around 13.4 m. Some 370000 metres of granular fill was compacted in all.

Mr Young said, "We used a Global Positioning System (GPS) to help us accurately locate the columns. It allows crane operators to view the columns on an LCD screen in their cabs, which means they can work day and night.

"We also supplied each rig with our in-house computer based data logger system to capture the depth and hydraulic system pressure in real time."

Because the area around the port is visited by pods of killer whales, a marine noise-monitoring programme was also established to measure the acoustic frequencies of equipment and how far away noise could be heard.

"If a pod was spotted within 7.5 km of the site, the environmental monitor had the authority to stop any work that produced noise exceeding 0.5kHz," said Mr Young. "Fortunately the monitoring demonstrated that our equipment had no effect on the whales and work could progress normally as the whales moved outside the zone."

With the marine densification project completed on time and to budget the Deltaport Third Birth Project (DP3) is scheduled for completion by autumn 2009.