Environmental Impact Assessment
Management Planning
Lachine Canal National Historic Site of Canada Management Plan
Context
The Management Plan for Lachine Canal National Historic Site of Canada has undergone a strategic environmental review in accordance with the Cabinet Directive entitledEnvironmental Assessment Process for Policy and Program Proposals . This federal environmental assessment process is a self-evaluation mechanism used by federal departments and agencies to determine, assess and generally mitigate the environmental impacts of projects or activities they plan to undertake. In accordance with Parks Canada’s Management Directive 2.4.4 on impact assessment, the scope of these environmental assessments extends to cultural resources, so that all the factors bearing on the assessment are included in the same report. The environmental assessment of this Management Plan is presented in a separate document entitled Évaluation environnementale stratégique du plan directeur du lieu historique national du Canada du Canal-de-Lachine . The following sections provide a summary of this document.
Methodological Approach
The environmental assessment of the Management Plan was carried out in several stages. First the general directions presented in the Management Plan were examined to ensure that they accorded with the mandate and policies of Parks Canada. Then the projects and activities involved in presenting the historic site were studied in order to identify stressors. The next step consisted in characterizing the impacts identified according to their duration (temporary or permanent impact) and intensity (no impact, weak impact, impact that could be mitigated or not, or unknown impact). Finally, general measures intended to reduce anticipated negative impacts were defined.
Scope of the Environmental Assessment
This environmental assessment is based on existing documentation as well as on the opinions of various specialists in the management of cultural and natural resources. The assessment takes into consideration both biophysical resources (soil, air, water, vegetation and wildlife) and cultural resources (cultural landscapes, built heritage and archaeological resources). However, the study of cumulative impacts deals only with the resources that are considered significant in the environment.
Compliance of the Management Plan’s Strategic Directions
The projects and activities proposed in the Management Plan for Lachine Canal National Historic Site of Canada in no way compromise the commemorative integrity or the knowledge and appreciation of this heritage. Indeed, on the whole, they provide support for these components of Parks Canada’s mandate. Only a few of the statements could eventually come into conflict with the preservation of the commemorative integrity and the knowledge and appreciation of this cultural and natural heritage.
Identifying Impact Sources and Evaluating Preoccupations
The projects and activities involved in presenting the Lachine Canal are likely to have an effect on the intrinsic value of both the cultural and natural resources. The analysis of the negative impacts of these projects and activities had to consider the extent and intensity of the impacts and whether or not their effects would be permanent. It took into account the fact that the work concerned would be done in compliance with appropriate practices and resource integrity preservation statements.
The analysis showed that, on the whole, the anticipated impacts on natural resources, except water quality and noise, are not very worrisome. However, the anticipated impacts on cultural resources are a source of concern, although they can be mitigated.
Apart from the negative impacts that could stem from the various projects considered in the Management Plan, the main environmental issues concern water quality in the canal, the resuspension of contaminated sediments and the preservation of the site’s commemorative integrity.
Construction activities related to the reopening of the canal to through navigation could affect water quality and the management of contaminated canal-side land. However, using the canal for through navigation should not in itself be a major source of water contamination, provided that boats do not discharge sanitary effluents into the canal and specific measures are taken in regard to fuel supply.
In Parks Canada’s opinion, certain maintenance, repair and development work associated with reopening the canal to through navigation could result in direct exposure to contaminated sediments and require ad hoc decontamination measures. Furthermore, sediments might be resuspended and carried downstream, thereby affecting the river’s ecosystem. Parks Canada is therefore committed to taking appropriate measures—even closing the canal—to avoid jeopardizing the health of users and workers and that of the ecosystem.
Activities connected with reopening the canal to through navigation and with several of the projects proposed in the Management Plan involve excavation work for the purpose of restoring structures, enlarging certain basins that have been filled in, or building foundations. It is possible that contaminated sites posing risks to the environment and human health will be uncovered in the course of such work.
Other issues concern more specifically preserving and presenting heritage components associated directly with the canal so that users can benefit from them without altering their value or significance, as well as preserving and presenting the industrial components and resources related to hydraulic power. Actions connected with developing the canal and its banks for nautical and canalside use should be carried out in such a way that they do not have an adverse effect on valuable cultural components.
Cumulative Impact
Certain components of the plan to reopen the canal to through navigation could possibly have an effect on water quality during the development phase of the work. Indeed, contaminated sediments are likely to be resuspended during dredging operations, which might be carried out at several locations at the same time. In such situations, water quality should be managed so as to prevent downstream areas from being affected.
Discharges from sewer mains and storm water overflow pipes into the canal compounds the already deteriorated quality of the water entering the canal from the river. However, this cumulative impact on water quality in the canal is temporary.
Furthermore, construction activities will probably have a cumulative impact on noise levels. Indeed, based on the activities involved in reopening the Lachine Canal to through navigation and several of the projects proposed in the Management Plan, there will be a notable increase in noise levels during construction work.
The combined effects of time, successive stages of development and restoration work and increased numbers of visitors to the site all represent major sources of stress for its cultural resources, which are essentially fragile and non-renewable. Failure to develop an approach that is respectful of the canal’s “heritage fabric,” or to exercise some form of control over the development of reception and visitor facilities, may jeopardize the preservation of essential features of this national historic site.
Mitigation Strategies
To counteract the probable negative impacts stemming mainly from the proposed reopening of the canal to through navigation and mitigate the impacts on biophysical resources, the following strategies have been or should be adopted.
A monitoring program has been put in place to assess discharge quality and frequency and determine, if necessary, whether illegal discharges have been occurring. The various bodies concerned are involved in the program. Remedial measures have already been or will be taken.
Specific measures will be applied to managing contaminated sediments during the construction phase of the work so as to minimize risks to public health and the environment. An optimization plan will be produced out before work plans and specifications are drawn up.
Measures for managing contaminated soils will be based on the risk such soils pose, as well as on the province’s contaminated soils management policy.
Appropriate professional and technical consultation and monitoring measures should be applied during all operations relating to heritage resource presentation that might have an impact on the cultural landscape and built heritage. In general, cultural resource protection will take precedence over all other types of work.
Conclusion
The results of this environmental assessment lead to the conclusion that, on the basis of the knowledge currently available, the presentation concept adopted for this site is satisfactory in terms of both the environment and heritage. As a whole, the plan’s strategic directions are consistent with Parks Canada’s mandate and management policies.
In strategic terms, the environmental preoccupations raised by the presentation of the Lachine Canal are related to water quality; the management of contaminated soil and sediments and their potential impact on the health of workers and the general public; the potential resuspension of sediments as a result of canal use (navigation and lock operation); noise levels; and, finally, any impact on the canal’s commemorative integrity. These preoccupations are associated mainly with the reopening of the canal to through navigation.
The principal environmental issue is related to the risk of resuspending sediments. The Joint Environmental Assessment Panel for the Lachine Canal decontamination project said in its report that the risks posed by this phenomenon would have to be assessed. It believed that if the risks were acceptable, the option of non-intervention remained valid. The results of a risk modeling study (Tecsult 1997) and in situ tests conducted in 1998 and 2001 showed that re-establishing through navigation would not involve any real risk of resuspended sediments as a result of motor navigation and lock operation under normal navigating conditions. In 2002, Parks Canada, in conjunction with Environment Canada, introduced an environmental monitoring program for the navigation season, as well as an action plan in case sediments were stirred up in the Lachine Canal.
The potential negative impacts of greatest concern can be mitigated through known techniques and methods or other time-tested means. In-depth environmental assessments should be conducted at a future planning stage, once projects and implementation phasing have been sufficiently defined. A detailed environmental assessment of the various components of the Management Plan, particularly those essential to reopening the canal to through navigation, was conducted in accordance with the provisions of theCanadian Environmental Assessment Act.