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Sydney Tar Ponds Solidification/Stabilization - Nova Scotia

  • Solidification/Stabilization of approximately 746,000 CY of impacted soft sediment
  • Pneumatic addition of cement in a dry form was introduced to the waste under custom fabricated cement conveyance boxes
  • Cement-waste mixing performed using multiple hydraulic excavators
  • Construction of a lined channel through the solidified/stabilized mass to convey storm water discharge into the harbor
  • Installation a site-wide cap over the treatment areas

ENTACT provided Solidification/Stabilization Technical Assistance, including proposal preparation, cost estimating and completion of required submittals, to our Canadian Joint Venture Partner, Nordlys, for the Sydney Tar Ponds project in Nova Scotia. ENTACT performed the Solidification/Stabilization mix designs in our bench scale treatability lab that consisted of testing waste from three distinct ponds with locally available reagents using various combinations of Fly Ash, Bed Ash, Bottom Ash, Slag, GU Cement, and GU Cement-GGBFS (1:3 blend by weight). Cured samples were tested in 14 and 28 days. The Solidification/Stabilization field pilot program was successfully completed which proved the proposed mix design’s viability of 14% to 16% cement addition to waste by weight.

During construction, ENTACT provided Solidification/Stabilization supervision personnel and Quality Control Officers (10 individuals) to oversee the work. Scope included solidification/stabilization of approximately 570,000 cubic meters (746,000 cubic yards) of impacted soft sediment, with treated sediment being required to achieve a permeability less than 1 x 10-6 cm/sec; minimum unconfined compressive strength of 25 psi; and modified leachability limits specific to this project. The pneumatic addition of cement in a dry form was introduced to the waste under custom fabricated cement conveyance boxes with cement-waste mixing performed using multiple hydraulic excavators. Other aspects of the work included construction of a lined channel through the solidified/stabilized mass to convey storm water discharge from the City of Sydney into the harbor, and installation a site-wide cap over the treatment areas.