418451 - Forest Lawn Ravine Storm Channel Rehabilitation

Purpose
The City of St. Albert is requesting proposals from qualified, licensed and professional consulting firms to provide engineering design services for the rehabilitation of the storm channel within the Forest Lawn Ravine. At this time, the City is only looking for design services, however the City reserves the right to extend this contract or proceed with an additional request for proposal for tendering and construction services.

Background
The Forest Lawn Ravine Storm system was constructed in the 1970s and consists of:

• one inlet and one outlet headwall and grates
• approximately 345m of concrete open channel measuring approximately 8’ X 1’
• two storm crossings at Sir Winston Churchill Avenue (SWCA). One 84” CMP overflow culvert and one 24” concrete storm main which ties into the storm system on SWCA via a manhole in the boulevard of SWCA.

In 2017, the storm crossings under SWCA and approximately 50 m of the concrete channel at the downstream end was replaced and widened. This project is to address the remaining portions of the concrete channel as conditions have worsen over the last few years. The project must take into account the following:
• Perform a safety analysis of the ravine with regards to the close proximity of the trail to the storm channel and surge areas. Make recommendations to improve public safety and provide costing for options;
• Evaluate the side channel erosion in the open channel as a result of changes to the headwalls on the upstream and downstream ends;
• Undertake utility locates, geo-technical investigation and site survey required to fully understand risk and support preliminary design;
• Evaluate the condition of the concrete channel and propose methods of rehabilitation;
• Provide a hydraulic assessment of the channel as during storm events as the majority of the flows exceed the channel cross section and act as a river flow. Review velocities and flows of the channel to ensure rehabilitation solution addresses the extreme volume of flows experienced in the channel;
• Review the potential for installation of energy dissipators within the channel to slow flow and reduce side bank erosion of the channel;


It is the City’s hope that the assessment of the existing channel reflects a rehabilitation method that does not require the removal of the entire channel but reflects more in place methods to repair condition.
The successful consultant will be responsible for the provision of project management and construction management services for the duration of the project.