The expectation that waste and stormwater infrastructure may be in place for 50 to 100 years makes it paramount to address both historic and future climate considerations. Climate models have emerged in recent years as a new tool available to local governments, such as the City of Castlegar’s, to manage the impact of extreme rainfall due to climate change on waste and stormwater infrastructure. Tools such as Engineers Canada’s PIEVC protocol were developed for municipalities like Castlegar to assess exactly what risks are posed by extreme rainfall and how they can be accommodated in stormwater infrastructure design, maintenance, and operations. Cost and benefit analyses were an extremely useful tool, as they revealed that in several instances a 15 to 20 percent increase in the volume of waste and stormwater flows may add one percent to the initial cost of construction, but it would help avoid the risk that the infrastructure becomes prematurely obsolete and needs to be replaced in 20 or 30 years because it is unable to cope with predictable increases in flows. Knowing that in several instances, a small additional investment in waste and stormwater infrastructure would have an excellent payoff in the long-run prompted the City of Castlegar to apply for funding to assess the impact of climate change on the city’s infrastructure. Thus, with the funding of the Columbia Basin Trust, Castlegar was able to apply Engineers Canada’s PIEVC Engineering Protocol for a Climate Change Infrastructure Vulnerability Assessment. After identifying the significant threats climate change posed to local infrastructure, the City of Castlegar was able to begin developing a plan for how to work with stakeholders to analyze historical climate data, develop future climate models, analyze specific climate scenarios, and ultimately build a catalogue of vulnerable infrastructure based on PIEVC protocol that would inform proactive climate change adaptation plans in the future.
In 2009, the Columbia Basin Trust provided the City of Castlegar with funding to apply Engineers Canada’s Public Infrastructure Engineering Vulnerability Committee (PIEVC) Engineering Protocol for Climate Change Infrastructure Vulnerability Assessment. The study focused on the impact of climate change on the city’s stormwater infrastructure, as local officials and other stakeholders were concerned that changes to watersheds surrounding Castlegar threatened the reliability of local stormwater infrastructure. Castlegar conducted a vulnerability risk assessment of stormwater infrastructure under PIEVC protocol to identify the components most vulnerable to climate change impacts. The protocol followed five distinct steps: project definition, data gathering and sufficiency, risk assessment, engineering analysis, and recommendations. A team from the Pacific Climate Impact Consortium helped develop climate models for the City of Castlegar that projected more rain and less snow, with an increased risk of extreme rainfall events that could lead to more frequent and larger flow events in streams and stormwater management systems. The climate projections and vulnerability assessments revealed that Castlegar was indeed vulnerable to climate change. Specifically, after applying 11 climate change events to 35 infrastructure elements, it was determined that 34 of the 35 stormwater infrastructure elements studied in Castlegar were at medium or high risk, including 10 at high risk. The study informed recommendations which included reviewing the 10 high risk infrastructure elements to develop an action plan with timelines and budgets. Actions such as the development of a mitigation strategy to prevent erosion for a creek, resizing certain culverts and storm sewer trunks, and improving sections of a stream channel to carry expected peak flow were amongst the specific recommendations of the study. The Stormwater Infrastructure Climate Change Vulnerability Assessment contributed to several infrastructure rehabilitation efforts since 2012 and helped develop a comprehensive climate change adaptation strategy for the City of Castlegar.