Shoreline erosion has been a concern for the city of Montmagny for a long time. The erosion process appears to be accelerating over time, and interventions will eventually be needed to protect waterfront infrastructure. An erosion zone north of the wastewater settling ponds threatens these facilities in the medium term.
In 2014, Phase 1 “Experimentation on vegetation techniques of an erosion zone along the St. Lawrence River banks” was conducted on this site. It allowed Biopterre to develop a model consisting of alternating strips of willow and herbaceous plants established parallel to the bank. This could improve the survival of implanted species and efficiently slow the erosion process down. The Sud-de-l’Estuaire Zip Committee was inspired by this test and planted 21 000 willows and 12 000 herbaceous plants in 2016, in the same area. Phase 2 began in 2016, when three erosion sites in Montmagny Bay were targeted. In spring 2016, Ecogespro (plant engineering specialist) and Biopterre set up three demonstration plots showcasing stabilization techniques tailored to the three prominent erosion problems. The state of the plots and erosion control efficiency was monitored from 2016 to 2018 and two plots stood out.
The tests conducted during phases 1 and 2 provided concrete answers to the City of Montmagny and led to Phase 3 in 2020. This phase was carried out in collaboration with experts from Terra Erosion Control Ltd and Englobe. It consisted of conducting a feasibility study aiming to protect the banks of the Pointe-aux-Oies Camping. Phase 3 led to the identification of different plant engineering techniques and to the characterization of the targeted site according to three erosion zones with distinct problems. In this study, plant engineering techniques supported by technical drawings were designed for each of the three zones. A preliminary assessment of the technical and financial feasibility of the proposed concepts was then carried out. Finally, the strengths and limitations of each technique were addressed. Phase 3 of this set of experimental projects could lead to a proof of concept that would allow to update and edit currently proposed concepts, followed by the implementation and testing of plant engineering techniques recommended in the feasibility study.