Toronto Pearson International Airport, Ontario 2012
As part of a tunnel rehabilitation project for the Greater Toronto Airports Authority (GTAA), a backwall grouting program was prescribed as one of the measures to be undertaken to mitigate continual water seepage into two infield tunnels.
Years of seepage into the tunnels had accelerated degradation, while ice build-up during the winter months posed safety concerns within the two concrete tunnels, which are critical corridors for the flow of cargo and perishable goods to and from aircraft at the airport.
Based on results obtained from soil samples and in-situ hydraulic conductivity tests, ECO designed and directed a multiple hole, multiple pass backwall grouting program to reduce the hydraulic conductivity of the soil formation immediately adjacent to the infield tunnel wall and to seal off any preferential flow pathways that may have existed at the interface between the exterior face of the wall and the native backfill material. As the soil formation behind the structure contained a significant percentage of fines in its composition, the program consisted of drilling a series of holes through the concrete wall and injecting the soils immediately behind it with a solution grout.
ECO’s CAGES (Computer Aided Grouting Evaluation System) was relied on to continuously monitor in real-time the effective pressure, flow rate, grout spread and permeability of the medium being grouted. The use of CAGES ensured that an effective barrier to flow was created.
In addition to designing and monitoring the twenty-four-hour-a-day grout injection program, ECO’s role as the grouting engineer and designer was to design all the grouting systems and grout formulations, and to provide hands-on training and supervision of the Contractor’s Staff onsite.