Cutter soil mixing delivers big savings

Keller has completed its first project in Canada using cutter soil mixing (CSM), a technique that eliminates the need for numerous rigs and saves a huge amount of time. We spoke to the team to find out more…

When it’s finished in spring 2019, the Platform development complex in Port Moody, British Columbia will offer more than a hundred stylish houses and condos along with retail, commercial, and social spaces.

As part of the project, Keller performed earth retention and excavation support for a section of the development – 2718 Clarke Street, a 38m-tall by 79m-wide property.

“The ground in this area features deltaic alluvial flow deposits with few obstructions, making it ideal for CSM,” explains Field Engineer Johannes Reinisch. “Developed from diaphragm wall technology, CSM uses two sets of counter-rotating, vertically mounted cutter wheels that cut the surrounding soil and blend the injected cement slurry with the in-situ soil to form soil cement panels.”

“The work of three drill rigs”

The CSM shoring wall was designed as a temporary earth retention structure, anchored to support the maximum excavation depth of almost 11m and embedded in a silt layer to restrict groundwater seeping into the excavation pit. Construction included the supply and installation of almost 90 650mm-thick CSM panels to a depth of up to nearly 16m.

“The significance of CSM technology lies in its efficiency and consistency,” adds Assistant Project Manager Anand Mitchell. “Had we approached this project with an alternative technique, it would have taken three times as long. The cutter tool takes about two hours to do the work of three drill rigs, creating the panels in the ground.”

The main challenge was installing the panels in tight corners close to an adjacent building on the west side of the property and ensuring they were precisely vertical to avoid intrusion into the planned excavation pit.

Thorough planning

“Reaching the planned production rate required skilled workmanship to ensure safe completion on schedule,” says Anand. “Site logistics, safety protocols, and production sequences needed to be thoroughly planned, reviewed, and executed on each work shift.”

Due to limited storage space on site, delivery of cement and H-piles was timed to coincide with the construction schedule. Keller then completed the installation of 124 H-piles within the CSM panels, even finishing a week ahead of schedule.

Highly recommended

The client was delighted with Keller’s hard work and innovation.

“Working with Keller was a big win for us and we highly recommend them,” says Kris Hellens, Senior Project Coordinator for Aragon Construction Management Corp. “In addition to the excellent backend support from their office staff, their site crew consisted of some of the most helpful, cooperative and responsive people I’ve had the pleasure of working with. Keller’s whole team was able to react on the fly to changes in plan without any issues and provided constructive insights on how to get the best-possible product.

“Furthermore, Keller’s innovative materials-testing solutions allowed us to meet the requirements of our consultants without sacrificing schedule, and their precision drilling saved us valuable square footage within the site.

“The soil mixing method proved to be fast, efficient, and minimally disruptive, resulting in no complaints from the neighbours and saving us from having to perform repairs to the adjacent properties.”

Keller is now scheduled to install two levels of anchors for a separate scope of work.