Conmee Township

Post Flood Drainage System, Bridge Foundation and Slope Stabilization Assessment, Design and Construction Administration

Background and Scope

On May 28, 2012, Conmee Township, along with the Municipality of Oliver Paipoonge and the City of Thunder Bay, declared a state of emergency (CBC, May 28, 2012). This state of emergency was the result of an estimated 25 to 108 mm of rainfall recorded for the region by the Lakehead Region Conservation Authority (LRCA) in less than a 36-hour time period. The prolonged precipitation produced flood conditions that resulted in the degradation and destruction of municipal roads, storm water infrastructure and water crossings. In response to this flood, TGE was the prime consultant selected to conduct a comprehensive bridge, drainage system and road slope assessment to provide recommendations for improvement to the impacted system.

Project Challenges

This project was challenging because of the large and multiple watersheds, the limited understanding of existing infrastructure, the environmental sensitivities in the region, and the permit and approval requirements from the LRCA and the Ministry of Natural Resources and Forestry (MNRF).

Engineering Solutions

TGE first conducted a post flood bridge and drainage study which identified recommendations for replacement and changes to the existing infrastructure which included bridges, road embankments/slopes and culverts. TGE was then hired to perform a detailed investigation, design and tender preparation of the recommendations indicated in the study.

TGE prepared the detailed design and tender specifications for the replacement of the Maxwell Bridge and the repair of two other bridges along Mokomon Road East. The work included hydrology, geotechnical engineering, structural and environmental design and work permits.

Four slopes (three along Mokomon Road and one on Hunt Road) experienced movement, erosion and/or failure that require corrective measures and restabilization. The design included engineered fill, gabion baskets, rock armoring, and road-side drainage improvements. Mokomon Road required complete reconstruction measures to be put in place to ensure the stability of the road.

TGE was also responsible for a comprehensive culvert replacement program for drainage and infrastructure. More than 25 critical culverts ranging from 600 to 2000 mm in diameter were designed, and the associated tender specifications were prepared. The design included clearing, excavation, grading, placement of topsoil and seed, placement of rock protection, installation of geotextile, rolled erosion control products, culverts, silt fences, sand bag barriers, straw bale flow checks and permit approvals.