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ST.FRANÇOIS RIVER
BANK STABILIZATION
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CLIENT
Department of Indian Affairs and
Northern Development and
Odanak Indian Reserve
LOCATION
Odanak Indian Reserve
DURATION
2003
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PROJECT DESCRIPTION
En 2002, Teknika HBA
was mandated by the Odanak Indian Reserve Band Council to build a new wastewater treatment plant on the reserve. The firm produced drawings and specifications and supervised construction works. Financed by the Department of Indian Affairs and Northern Development, this project was also the subject of a preliminary environmental assessment according to the Canadian Environmental Assessment Act (CEAA) in order to obtain the necessary authorizations for its realization.
A particular issue was linked to the development of this plant on the banks of the St. François River. Indeed, a geotechnical study concluded that major modifications had to be made to the bank to ensure the stability of sanitation infrastructures. By doing so, the natural bank, on the right
side of the infrastructures, had to be destroyed and redeveloped in conformity with the geotechnical stabilization works recommended by the specialized firm in its study. The complete redevelopment of the natural bank also provoked the complete destruction of the existing fish habitat.
Within this context, the Department of Fisheries and Oceans was called in. We then undertook discussions with this department in order to come, within the context of a protocol, to compensation projects for the lost fish habitats. A compensation agreement focusing on the restoration of the bank using plant species armouring, notably in the 2-year recurring flood zone, was quickly concluded and works started in the fall of 2003. To meet these requirements, the plant species stabilization concept took into consideration the various levels of water in order to encourage the presence of sea grass at the bottom of the slope through the construction of a bench colonized by plant species favorable to fish-breeding species in this sector of the river.
Although the requirements from the Department of Fisheries and Oceans only focused on the 2-year recurring flood zone, the entire slope was the subject of plant species stabilization works so as to regenerate the marginal vegetation and give back its natural aspects to the bank. Not only will the plant species regeneration of the bank considerably mitigate the perturbation caused by the construction works of the various infrastructures, but it will also ensure the continuity of the recreated fish habitat.
Specifically, the plant species stabilization works were:
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installation of a fascine at the bottom of the bank; |
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installation of a branch mattress up to the 2 year recurring flood line; |
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installation of three brushwood fenders; |
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seeding of the soil left barren. |
These works were performed in several stages. First, we conducted a research of original beds to take samples of willow stems and then proceeded with the collecting of necessary quantities. While waiting to be reused, the stems were preserved in bundles of 30 stems in a local swamp on the reserve. These stems were then used for the construction of the fascine, branch mattress and brushwood fenders. The construction of the fascine and branch mattress required the insertion of cedar piles and the braiding of a metal thread between the piles to maintain the branches in place.
The works were completed with the installation of brushwood fenders and the addition of top soil on the armouring to encourage, among others, the striking of willows. Dogwood stems were incorporated in various parts of the infrastructure to increase the diversity and encourage the development of different roots, including the Cornus stolonifera and the Salix interior as well as superficial lateral development in other cases.
Works are the subject of a follow-up in accordance with requirements from the Department of Fisheries and Oceans. This follow-up started in January 2004 and will go on in 2005 and 2008. The follow-up of works consists of verifying the impacts of ices in winter and spring, the state of plant species and the general state of the premises so as to ensure that no illegal activity will impact the striking and growth of the plant species armouring put in place. The follow-up will allow the regular maintenance of plant species armouring.
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