Dredging

The Port of Thunder Bay is a busy commercial harbour with typically 6 million tonnes of grain shipments per year. Riggs was retained to address navigation concerns, exacerbated by low Lake Superior water levels.  

Our scope of services included:

• Pre- and post-dredging surveys.  - Side scan surveys.
• Sediment sampling and analysis.  - Canadian Environmental Assessment Act Screening report.
• Determination of channel width based on navigation review.
• Plans and specifications for dredging contract.
• Contract administration.
• Field review services during the project.

The Port Stanley harbour is located in Elgin County on the north shore of Lake Erie at the mouth of Kettle Creek.  

Riggs provided support to a business case study regarding the financial viability of the harbour and investigated the short term and long term fate of sediments deposited by Kettle Creek. Riggs provided future harbour development options and evaluated possible disposal of dredged sediment including open water disposal, with the following:

• Completed a comprehensive analysis of previous harbour dredging, along with sediment volumes removed in the past.  - Documented the inner and outer harbour environment, as the type of sedimentation differs in inner and outer sections.  - Evaluated the historical rates of harbour infilling. Rates of historical infilling were used to gauge future infilling rates, and thus estimate future dredging volumes and associated costs.
• Strategized maintenance dredging for both the inner and outer harbour.
• Investigated short term and long term fates of open water dredged material disposal and how deposited mounds will move and evolve with time.
• Utilized numerical modeling for quantitative assessment for all disposal options, and implicitly considered.
• Complex disposal site bathymetry.
• Multiple discrete dump operations from barges, scows and hoppers; and
• Quantification of dynamics of in-place dredged material mounds over the short term and/or long term.

Riggs was hired by the Elgin Military Museum to assist on the marine engineering components of the project that brought HMCS Ojibwa, a cold war submarine to Port Burwell, Ontario. Our tasks included ensuring that the harbour bottom was dredged to sufficient grades and the design of the shore transfer dock.