A recent expansion to the Municipality of Bluewater’s Stanley Landfill site included the need to restrict groundwater flow through permeable overburden along the western boundary of the site. Following a review of alternatives, a bentonite slurry trench cut-off wall was selected as the most effective and cost-efficient solution.
Construction of the cut-off wall consisted of a 3.5m deep pre-cut to the top of the permeable overburden layer. From there, a 1.0m wide bentonite slurry trench was constructed through the permeable layer and keyed into the impermeable material below. Depth of the slurry trench varied between 2.5m and 5.0m along the 220m length. Preparation of the bentonite slurry, and mixing of the slurry with excavated material prior to placement in the trench, took place onsite using temporary facilities constructed by the Contractor. Construction of the cut-off wall, including excavation and backfilling of the pre-cut, represented approximately $340,000 of the total project construction cost.
Construction of the bentonite slurry trench cut-off wall was completed during the fall of 2014. BMROSS provided design, contract administration and site review services as part of the overall landfill expansion project.