Targeted Environmental Analysis - Update to the Area of Encroachment in Fish Habitat (April 2015)
Note that this is a report summary. For a copy of the full report, please contact us.
Following the announcement of the Minister of Transport, Infrastructure and Communities of the construction of a New Bridge for the St Lawrence (NBSL), the government launched the NBSL Environmental Assessment (EA) on July 6, 2012. The project EA was prepared based on the project's preliminary engineering design elaborated in 2010, which projected end of construction in 2021. This EA was completed in October 2013.
Meanwhile, the Minister announced the completion of the EA as well as acceleration of the NBSL project. Due to the state of the Champlain Bridge, construction of the NBSL would be completed by December 2018, three years earlier than originally planned. Following this announcement, the reference design of the NBSL for construction was developed. The design showed that the temporary in-water works will occupy a larger area than previously anticipated, causing greater harm to fish habitat than was estimated in the EA. Infrastructure Canada (INFC) and Fisheries and Oceans Canada (DFO) therefore determined that the environmental effects caused by the increased encroachment of the project in fish habitat should be analyzed to ensure that appropriate mitigation measures can be identified. This document is the result of that analysis and is intended as an update to the EA with regard to the project's impact on fisheries.
Taking into consideration the accelerated schedule of the project, as well as the St Lawrence River's bathymetry the NBSL engineers proposed a reference design including construction methods for project implementation. This design makes assumptions of what the final design may be. However, it is important to note that the final designs and selected methods of construction are the responsibility of the private partner and will only be known when he is selected in April 2015. This reference design indicates that the temporary works to be constructed in shallow water will be larger than estimated in the EA. Various shallow-water construction methods have been analyzed, however, INFC believes the contractor will select the option of building jetties to facilitate construction on the bridge in shallow parts of the St. Lawrence River. This document discusses the temporary jetties that may be built at those sites. The area occupied by these temporary works would be 82,773 m2, rather than the 30,950 m2 estimated in the EA.
The temporary works will have an impact on fisheries as defined in the Fisheries Act, because they will cause fish habitat losses, are likely to interact with fish migration and to cause indirect effects, such as altering habitat downstream of the jetties. The fish habitat in the study area is well known and well documented. The habitat is diversified, which means that a variety of restriction periods apply and will have to be complied with by the Private Partner during the construction of the NBSL.
This study confirmed that all of the mitigation measures identified in the EA still apply to the project. Some of the existing mitigation measures have been enhanced to better reflect the impact of the temporary works discussed in this document. Additional mitigation measures have also been developed and will have to be implemented along with the existing measures. The new measures stemming from this study have been added to the Project Agreement with the Private Partner in order to formalize them for bidders on the NBSL project. The new mitigation measures are as follows:
- MPO-30 – Compensate areas where serious harm occurs at a ratio of 1:1.
- MPO-31 – Carry out 2D hydraulic modeling, which will predict the conditions (velocity, depth and direction of flow) at the entrance, middle and exit of each planned migration corridor during the operating phase.
The clarifications below are added to existing measures of the EA (CC-6 and MPO-2)
- CC-6b – Clarification: For the jetty located on the west bank of the Greater La Prairie Basin, the flow velocity in the migration corridors must be between 0.8 and 1.2 m/s during high-water periods. The water depth must be between 0.6 and 1 m during the same periods. Furthermore, rocks and boulders, sills, groins or deflectors will be installed to increase roughness in the migration corridors and thus reduce velocities during high-energy flow conditions. However, care must be taken to ensure that those structures do not impede fish passage during lower-energy flow conditions. Lastly, a minimum depth of 40 cm in the migration corridors is required during low-water periods; there is no minimum velocity. The flow in the migration corridors will be maintained at all times to create a downstream attraction flow.
- MPO-2b – Clarification: The design of the jetty east of Île-des-Sœurs will have to take into account the presence of the jetty to be built by the Jacques Cartier and Champlain Bridges Incorporated (JCCBI) upstream. Structures will be built between the two jetties to maintain a continuous current and to avoid creating stagnant zones.
Environmental monitoring was already planned for the NBSL construction phase. The conclusions of this report indicate that additional monitoring in relation to the impact of the temporary works will be needed. Furthermore, one major mitigation measure concerning fish habitat involves implementing compensation projects. The compensation planned for serious harm to fish habitat will be increased to reflect the revised temporary encroachment area estimated in this document.
Lastly, authorizations must be obtained under the Fisheries Act before any in-water construction activities can begin. The Private Partner will be responsible for obtaining those authorizations and for complying with all conditions of DFO authorizations.
After taking into consideration the full EA reports, as well as the update provided by this document, INFC and DFO are of the opinion that, given the implementation of the mitigation measures identified in the EA reports and in this report, the increased encroachment of the temporary works on fish habitat is not likely to cause significant adverse environmental effects.
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