In order to mitigate soil losses into an abandoned sewer, ACT was contracted to perform compaction grouting and stabilize the soils above and around the sewer. The compaction grouting program was performed at depths of up to 169 feet deep, likely one of the deepest compaction grouting projects ever undertaken. Thirteen arrays of compaction grout columns were installed, totaling 7,000 lineal feet to treat and densify the soil.
The compaction grout used was designed by ACT. It was specifically formulated to provide a low slump mortar like consistency. The compaction grout was supplied in prepackaged bags to maintain a quality end product. Mix testing was performed ahead of the production work to ensure the materials were performing as specified. During the production phase, additional routine quality control testing of the compaction grout being placed was performed.
The work was completed in a residential area within the City of Toronto requiring detailed planning and execution of the work to minimize disruption to the homeowners. All utilities in the vicinity of the work were carefully mapped out prior to the start of the work. By adjusting some of the planned hole location, all existing utilities remained intact and were not disturbed.