Port Hope Harbour

Harbour

 

  • Approximately 120,000 m3 of waste (volume of sediment after dewatering)
  • Bounded on the west by the Cameco Port Hope Conversion Facility, on the east by the Centre Pier, to the north by Hayward Street and to the south by Lake Ontario

Remediation/Restoration Plans

  • Contamination exists as accumulated sediment in the bottom of the Turning Basin and Approach Channel
  • Sediments are typically soft silts and clays, with sand and gravel more common in the corners and edges of the Harbour, underlain by hard till or bedrock
  • The Port Hope Harbour will be remediated by hydraulically dredging the sediment, pumping it into geosynthetic containment tubes on the Centre Pier for dewatering from where it will be transported by truck to the LTWMF
  • Existing Harbour walls will be supported or replaced in advance of the dredging
  • A heavy-gauge geotextile silt curtain will be installed to contain suspended sediment within the controlled area
  • The Harbour work area will be protected from wave damage by a floating wave attenuation system designed specifically for dissipating wave energy in harbours
  • Two sediment dewatering areas will be constructed to house the containment tubes and graded so that drainage water is directed towards the primary drainage water retention lagoons.

Sediment Removal

  • A hydraulic dredge will be used to remove the full depth of the sediment
  • Sediment will be pumped through a floating pipeline into the containment tubes and polymers will be added to facilitate efficient dewatering through the acceleration of flocculation
  • Once each sediment containment tube has drained, it will be filled again with dredgeate, allowed to drain and the process repeated until each sediment containment tube is full of sediment (i.e., no “free liquid” drains from the tube)
  • Sediment containment tube filling will rotate through the two sediment dewatering areas minimising the need to stop dredging during dewatering or preparation for transport to the LTWMF
  • Odours associated with the sediment will be monitored and managed with odour controlling substances, as appropriate


Restoration of Site

  • Once dredging and transfer operations are complete the Harbour and Centre Pier areas will be restored to facilitate subsequent remediation of the Centre Pier. All non-contaminated low permeability soil will be temporarily stored on Centre Pier for use as backfill following the remediation

Special Considerations

  • Resident fish in the Harbour will be directed outside of the controlled area by seining and a silt curtain will be installed to prevent fish from re-entering the Harbour
  • To reduce potential effects on fish migration, installation of the silt curtain and the wave attenuation system in the Outer Harbour, will take place during the summer
March 29, 2018