Seine River Excavation – Ste. Anne, Manitoba

Project Description

Project Overview

No Limits Underground completed at-grade dredging of the Seine River channel leading into Ste. Anne, Manitoba. The work involved removing accumulated debris to restore channel capacity and reduce flooding risk, along with repair of the existing sluice gate that controls downstream water levels. The project was completed under winter conditions with active environmental and fish-habitat controls in place.

Key Challenges

· Winter construction conditions with approximately 12+ inches of surface ice above water.

· Marsh-like riverbed conditions caused by long-term sediment buildup.

· Live fish present within the active excavation area.

· Deep, confined-space access to the sluice gate cell.

Project Scope 

· De-icing of the river channel.

· Construction of cofferdams on both sides of the sluice gate and excavation area.

· Controlled dewatering with continuous aeration and fish protection measures upstream and downstream.

· Channel excavation using GPS-controlled elevations.

· Material stockpiling.

· Regrading of river shorelines.

· Sluice gate inspection and repair.

Solution and Outcome

NLU addressed site and environmental challenges through careful planning and specialized equipment selection. A 30-ton long-reach excavator with a 60-foot boom was utilized to excavate and grade the riverbed once the channel was dewatered, allowing the equipment to remain positioned on a single

shoreline and eliminating the need for rig mats while reducing the risk of equipment instability. A 20-ton track loader paired with an additional 30-ton excavator was used to efficiently manage and stockpile excavated material.

Fish within the coffer dammed area were safely captured and relocated upstream by an MTI-approved contractor specializing in fish salvation. Access to the approximately 25-foot-deep sluice gate cell was completed using specialized confined-space equipment operated by certified NLU personnel. The river channel and sluice gate were successfully restored, re-establishing controlled water flow and long-term flood protection for the community.