Metro Vancouver is upgrading their NW Langley WWTP facility with the construction of four new secondary clarifier tanks and ancillary structures.
Ground Improvement by Vibro Replacement stone columns was required beneath and surrounding the proposed tank foundations to mitigate the potential of soil liquefaction and mitigate the extent of lateral spreading towards the adjacent Fraser River during the design seismic event. Stone columns were installed using wet top-feed methods to a maximum treatment depth of 30m. The site’s interbedded and very fine sandy soils proved to be some of the most challenging soil conditions Menard Canada has ever worked with. Several systematic trial areas were carried out to determine the optimum combination of stone column spacing and installation methodology in order to meet the Engineer’s stringent CPT based performance criteria. Two Vibro rigs worked simultaneously on a double shift basis for a period of 4 months to meet the client’s schedule.