Three low-permeability cut-off walls were required for seepage control along the upstream toe of two new dams as part of the Lac des IIes (LDI) Water Management Facility Works. The LDI palladium mine is located 135 km North of Thunder Bay, Ontario, Canada. Jet grouting was used to create the low permeability cut-off walls by installing overlapping soil-cement columns. Jet grout columns were constructed using the double-fluid process. A comprehensive quality control program was implemented to ensure that specified geometric properties and performance requirements of the cut-off wall were achieved. An Acoustic Column Inspector (ACI) tool was used to verify the diameters of the pre-production test columns. All jet grout locations were predrilled to prevent difficulties resulting from geological conditions and to ensure adequate penetration into bedrock. A three-dimensional profile of each jet grout column installed was generated and updated daily based on the results of pre-drill hole alignment measurements completed at every hole. In-situ permeability testing was also conducted during the pre-production test program and during the installation of the production columns. Permeability testing was performed in-situ and on cast cylinders of soil-cement samples. The low permeability cut-off walls were successfully installed and satisfied the specified performance criteria. Jet grouting was performed between the months of February and May under challenging winter conditions. This paper focusses on the quality management program (QMP) that was implemented to successfully complete this project.

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The York Durham Sewage System (YDSS) Interceptor Sewer construction spanned a total length of 5.5 km, which included a 1.4 km stretch of open cut construction and tunnelled stretch of 4.1 km, with four access shafts. Two of the tunnel access shafts were located in an environmentally sensitive area with water bearing cohesionless soils and considered as a potential geotechnical hazard for tunnel break-ins/break-outs. A combination of slurry wall and jet grouting was used to stabilize the ground and control groundwater flow at shafts #2 and #3, during break-in/break-out of the tunnel boring machine (TBM). This paper presents a case study, addressing the application of double fluid jet grouting technique to mitigate a significant geotechnical hazard at shafts #2 and #3 for the YDSS Interceptor Sewer Project.

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