Success Through Infrastructure Failure: A review of natural channel restoration in urban systems
Monday June 26 3:25pm-5:15pm
Leads: John Stille (Toronto and Region Conservation Authority) and Dean Woolley (Active Innovation Research Inc.)
In previous decades, many of the watercourses in urban systems were modified through channelization and armouring. The intent was typically to improve flood water conveyance, but this practice can in fact increase the chances of flooding downstream due to hydraulic pinch points. The channelization and armouring of these watercourses has also severely limited their ability to sustain biological function. Many of these channels have reached or are now nearing the end of their operational life expectancy and are in various states of disrepair. Failing channel infrastructure is now contributing to erosion in many places, which has raised the risk of localized flooding as well as damage to adjacent property and infrastructure. In recent years, through multi agency partnerships, many programs and projects have been initiated to find natural channel design solutions to this issue. A review of the successes and challenges associated with urban stream restoration with practical examples provided by the engineers, designers, project managers, practitioners and planners are beneficial to the build on positive outcomes and minimize negative impacts.
Keywords: Project Review, Urban Infrastructure, Storm Water Management, Key Performance Indicators, Practitioners, Restoration
Following the conference, presentations that have been made available will be linked here.
Clifton Coppolino1 and Karley Cianchino2
1Toronto and Region Conservation Authority, Toronto, Canada
2City of Brampton, Brampton, Canada
Throughout the Region of Peel, modifications to watercourses through channelization and various forms of armouring was a common practice supporting development and the conveyance of stormflows away from properties. Current knowledge has shown that channelization can increase downstream flooding and erosion. Moreover, channels that have been lined with concrete or other hard treatments have a limited ability to sustain ecological function or provide habitat for fish and wildlife. Many of these altered channels are in varying states of disrepair, the most severe of which have already failed. These channels are now contributing to varying levels of erosion, which raises the risk of local flooding and the potential for damage to adjacent property and infrastructure.
Working in partnership with the City of Brampton, Toronto and Region Conservation Authority (TRCA) Identified five priority reaches where concrete lined channels could be restored using natural channel design principles. This first project was completed in 2022, in coordination with the City of Brampton’s Ecopark Initiative which spanned 1000m of stream across three consecutive parks along the Don Doan trail in the Mimico Creek watershed.
The project involved the removal of a failed concrete lined creek bed and constructing a natural meandering stream with bed and bank treatments to improve stream morphology and habitat. Increased floodplain storage was achieved by restoring floodplain connectivity with associated wetlands at various points throughout the restoration site. Native trees and shrubs were planted in the riparian areas and through the parks. Upgrades to park amenities, including fitness stations and play structures, outdoor amphitheater, outdoor classroom, viewing nodes and more were installed as part of Brampton’s EcoPark initiative.
The project involved innovative design considerations as well on-site adaptation that was revealed during construction. The presentation will outline prioritizing the five reaches, project planning, design and construction of the first Natural Channel and EcoPark project, with discussion around successes and lessons learned.
Jeff Prince and Mariëtte Pushkar
Matrix Solutions, Kitchener, Canada
Over the last 20 years, the application of geomorphology and river engineering in Ontario has changed. As with anything, how we do things, evolves over the decades. This presentation will show ‘then’ and ‘now’ examples of constructed channels and features spanning our careers. Discussion will focus on changes that we have made to design/construction methods, awareness that we gained through the projects and subsequently applied, how the channel has naturalized, what were good ideas and worked… and some that weren’t…
Ed Gazendam. Ph.D., P.Eng.
Water’s Edge, Cambridge, Ontario
A design-build approach to project delivery offers many advantages over traditional design-bid-build approaches, including faster project delivery and lower overall cost. As a result, design-build is being used with increasing frequency in many sectors including transportation and buildings. It has however been used sparingly in the field of stream restoration. Many are wondering if a design-build approach will produce the same benefits for stream restoration projects
Farewell Creek is an important trout stream in Oshawa. Unfortunately, the Creek was eroding a gabion wall which was at risk of collapsing and blocking fish passage. The Creek was also threatening private property. The City of Oshawa decided to address the issues in a novel way. Recognizing that that they had been unhappy with several stream projects delivered using a traditional design-bid-build approach, they decided to use a design-build approach. The project was completed during the fisheries timing window in the late summer of 2022.
The presentation outlines the resistance to the D-B process and the driving forces behind the D-B process by using the success of the Farewell Creek Project as a case study.
Rob Myllyoja
Environmental Consulting & Technology, Inc. (ECT), Ann Arbor, Michigan, USA
In recent years, there have been many advancements in watershed management and river restoration methods. The number and scale of in-stream improvement projects has grown in Michigan due to changes in stream mitigation requirements and funding opportunities such as the Great Lakes Restoration Initiative (GLRI). However, the rapid rise in the number of on-the-ground projects does not always keep up with the state-of-the-science. This discussion will focus on lessons learned from several urban and suburban stream restoration case studies in southeast Michigan over the past 25 years.
Mariëtte Pushkar, Jeff Prince and Chris Moon
Matrix Solutions, Kitchener, Canada
Flood conveyance channels within urban areas are often situated within relatively narrow corridors that are flanked by property boundaries, crossed by municipal infrastructure, and may be adjacent to public amenities (parks, trails) that are established and relatively fixed in place. Aging and deteriorating erosion control materials or channel lining, and/or flood risk are a common impetus for municipal channel works, required within the footprint of the existing watercourse. This presentation will describe the physical challenges of the design objectives and settings in two projects within constrained settings, and how they were overcome by the design and construction teams. Primary design objectives include flood conveyance improvement and erosion risk management within the footprint of the existing watercourse; secondary design objectives focused on ecological enhancements.
Future upstream development in the City of London is expected to aggravate existing flooding concerns for Dingman Creek Tributary 12. Flood mitigation required culvert replacement and substantial channel lowering. The 700 m long channel corridor was designed through an integrated innovative engineering and natural channel design approach that promoted ecological function of the system through the incorporation of a bifurcated channel, rootwads, riffle logs, and others. Challenges of winter channel construction and culvert replacement, and the contractor perseverance required to overcome them will be shared.
The City of Kitchener initiated restoration of 1 km of Shoemaker Creek to address erosion risk of buried utilities (sanitary sewer and watermain), the degraded state of the concrete lined channel, and deteriorating outfalls; aquatic habitat was considered to be extremely degraded, barriers to fish passage were identified, and poor-quality riparian cover observed. Establishment of a naturalized channel and aquatic habitat measures within a narrow corridor will be demonstrated.
