Condition Assessment and Hydraulic Study from Ben’s Lake Structure to Lake 6 Outlet

Background: The reach extending from Ben’s Lake Diversion Structure to Lake Six conveys flows from the Vermilion River, as well as inflows from Watt Lake. The combined flows from the Vermilion River and Watt Lake are conveyed through this channel before discharging into Lake Six, located approximately 5 km downstream of the diversion structure. Recent inspections conducted by operations staff have identified that the waterbody located between Ben’s Lake Diversion Structure and downstream of the Lake Six outlet, comprising a portion of the Vermilion River and an adjacent lake, has become significantly constricted by dense aquatic and emergent vegetation, particularly cattails. These conditions may have reduced the hydraulic conveyance capacity of the channel. The canal consists of both constructed sections and naturally occurring sections, assessment of both sections are a part of the scope of this project. Accordingly, AGI requires a comprehensive assessment of this river reach is required to evaluate existing channel conditions, identify hydraulic constraints, and determine the extent to which vegetation and sediment accumulation are affecting flow capacity. A hydraulic analysis shall also be undertaken to assess channel performance and identify priority cleanout locations and potential remediation measures that would optimize channel conveyance capacity and improve overall flow conveyance. Objective: The primary objective of this study is to undertake a visual condition assessment and hydraulic evaluation of the Vermilion River reach extending from the Ben’s Lake Diversion Structure to downstream of the Lake Six outlet. The assessment shall identify channel constrictions and other factors affecting channel performance. The study shall evaluate the impacts of identified constrictions on the hydraulic conveyance capacity of the channel and assess their potential influence on upstream water levels and flood risk. Based on the findings, recommendations shall be provided regarding priority cleanout locations and other remedial measures required to restore and optimize channel capacity and flow conveyance.