CSA W205:19 pdf download – Erosion and sedimentation management for northern community infrastructure.
A few communities in Canada’s North (or higher levels of government on their behalf) have had legislated buffer zones available, or taken steps to legislate or regulate buffer zones, to protect at-risk terrain and proposed infrastructure. A few more communities in the past several years in each of the territories have also begun to obtain dedicated geohazard mapping to assist in land-use planning, and many of those mapping programs have been motivated by climate change adaptation considerations. However, many communities have had little or no official geohazard mapping or guidelines available for consideration in development planning, or the existing mapping or guidelines might be decades out-of- date, haphazard, and/or fail to accommodate the existing or prospective results of climate change. Therefore, where community land-use plans are being updated or developed, the preparers of those plans shall incorporate the findings of available site-specific studies to assist in the appropriate development of buffer zones and setbacks within their jurisdiction. Those involved in the development of site-specific buffer zones and setbacks as part of an infrastructure project might not be directly involved in the permitting process for that project. However, the need for planners to make use of the information might make it desirable or even necessary to implement a direct-reporting requirement for land-use-related decisions.
Although many of the physical processes affecting erosion and sedimentation on northern sea coasts and lakeshores are like those observed in southern Canada, others involving sea or lake ice, permafrost, and ground ice become more important in high-latitude settings. Thawing and erosion of ice-rich coastal and lakeshore sediments is a process that has been ongoing since the last deglaciation and will not be reversed given present climate trends. In these conditions, northern communities face the challenge of increased coastal or lakeshore erosion rates associated with increased exposure to waves and open water processes, sea or lake ice cover reduction, changes in ice dynamics, permafrost melting, and thermal erosion that can result in problems that require innovative engineering solutions. The process of creating an appropriate ESCP shall include, but is not limited to, the following elements: a) a site-specific and system-based evaluation of existing conditions, including an assessment of risk; b) identification of strategies for erosion and sedimentation risk management, evaluation of alternative strategies, and selection of a preferred strategy; c) if required, based on the preferred strategy, i.e., depending on the outcome of Item b): i) identification of engineering alternatives; ii) technical, socio-economic, and environmental appraisal of engineering alternatives; iii) selection of preferred engineering measures; iv) conceptual and detailed design of engineering measures; and v) preparation of construction drawings and specifications, including any requirements for sequencing and mitigation of the environmental impacts of construction activities; and d) monitoring, maintenance, and adaptive management requirements.
6.3.1 General Proper planning, siting, and design of coastal and lakeshore infrastructure and the measures taken to manage erosion and sedimentation risks for new and existing infrastructure requires a) a basic understanding of coastal and lake erosion and sedimentation hazards, including the potential or proven presence of ice-rich permafrost, sediment transport, and shoreline erosion and sedimentation processes; b) erosion rate information from the community, territorial or provincial government, federal government, scientific literature, or other sources; c) appreciation for the uncertainty associated with the prediction of future shoreline positions; d) understanding that siting infrastructure immediately landward of a regulatory setback line (where applicable in various regulatory jurisdictions) does not guarantee the infrastructure will be safe from erosion hazards; and e) appreciation for how diverse types of human interventions to mitigate or respond to erosion and sedimentation can impact the environment and erosion/sedimentation in adjacent areas. 6.3.2 Strategies to address coastal and lakeshore erosion and sedimentation 6.3.2.1 Strategies Strategies for managing coastal and lakeshore erosion and sedimentation risks to existing and proposed infrastructure shall be considered. Typical coastal and lakeshore strategies can generally be grouped as follows (adapted from BC MoE 2013): a) Do nothing or business as usual – this is not usually a viable strategy in areas where coastal or lakeshore erosion or sedimentation issues are problematic, but represents an important strategic option to consider as a benchmark or baseline scenario for comparing the consequences, costs, and benefits of other strategic response options.CSA W205:19 pdf download.
