Three Approaches to Managing Long-term Water Safety
You’ve heard it before: Canada’s water is under threat due to climate change, growing demands on limited renewable resources, toxic water pollutants and inadequate mitigation efforts. We’ve been faced with Walkerton’s tainted drinking water, felt the effects of severe storms made more frequent by a changing climate, and seen summer droughts that have cut water flows in rivers and streams.
Plentiful supplies of clean, potable water are crucial to our future societal, environmental and economic health. Almost three-quarters of the people who live in Ontario rely on water drawn from surface sources, such as the Great Lakes. The remainder depend on groundwater supplies.
The challenges are daunting, but TRCA has been working diligently to manage the waters across our jurisdiction since our inception almost 60 years ago. In 2012, we advanced strategies to guide our work in flood management, we moved ‘outside the box’ looking at new technologies to reduce stormwater runoff, and we developed updated watershed plans.
Reducing the risks of flooding
One of the principal mandates of TRCA is to reduce the risk to life and damage to property caused by flooding. We do this, in part, by providing local agencies and the public with advance notice, information and technical advice so that they can take appropriate action during severe rainfall events and flood related emergencies. We also manage, monitor and maintain the various flood protection structures located throughout the GTA.
TRCA’s Flood Management Service (FMS) was formed in 2011, consolidating our expertise in water resources engineering, infrastructure maintenance, risk management, data acquisition and hydrometrics under one program within the Ecology Division. The new service is better positioned to prepare and respond to the challenges of our changing environment, meet the needs of our municipal partners, and protect the health and wellbeing of The Living City.
Today, FMS monitors watershed conditions 24/7 and issues Flood Messages as needed, identifies areas at risk of flooding and coordinates with stakeholders to mitigate those risks, develops outreach programs about the hazards of flooding, and provides professional guidance, reliable data and support to TRCA’s municipal/regional partners and the public.
The completion of the Flood Infrastructure State of Repair Report marks an important first step toward creating a long-term capital asset management plan for TRCA’s flood control infrastructure. It’s a plan for how we are going to reduce flood risks in the GTA.
Laurian Farrell, Senior Manager, Flood Risk Management and Infrastructure, Ecology Division, TRCA
In 2012, FMS renewed the Wet Weather Flow Study Monitoring Program with the City of Toronto. Since 2009, Toronto has retained TRCA to install and monitor 14 water sampling stations on watercourses entering the city to determine the urban impacts on water quality and to assess whether upgrades to stormwater systems are having a positive effect.
After several years of development, TRCA’s Flood Protection & Remedial Capital Works Strategy was completed (www.trca.on.ca/dotAsset/164334.pdf). The Strategy provides a roadmap for TRCA to undertake risk reduction projects by identifying and prioritizing areas of high flood risk. The Strategy also provides guidance on potential remediation options.
Another milestone for the FMS was the completion of The Flood Infrastructure State of Repair Report, which documents the current condition of TRCA-owned flood infrastructure and the impending capital investments required to maintain proper flood protection. TRCA currently owns 10 dams and 15 channels and other flood control structures. The report examines and assesses each structure, notes any major deficiencies, and categorizes them in terms of the “impact of failure” and the “probability of failure” using a risk management matrix.
Lastly, two major flood maintenance projects were completed in 2012: the Stouffville Channel clean-out and Phase 3 of the Yonge/York Mills Channel clean-out (partially funded under the Ministry of Natural Resources’ Water and Erosion Control Infrastructure program).
Reducing stormwater runoff through new technologies
Stormwater refers to rainwater and melted snow that flows off pavements, roofs and other hard surfaces. Under natural conditions, much of this runoff is intercepted by vegetation (and later returned to the atmosphere through evapo-transpiration) or absorbed into the ground to replenish aquifers. The remainder flows into rivers, lakes and wetlands. In urbanized areas, however, impervious surfaces, such as paved roads and roofs, prevent precipitation from soaking into the ground. Instead, the water runs rapidly into storm drains, municipal sewers and drainage ditches and then directly into rivers, lakes and wetlands. On its way, it picks up sediment, road salts, heavy metals, oils, bacteria, and other harmful pollutants.
Stormwater management is vital to protecting our water by managing the quantity and quality of runoff generated. Modern approaches consist of practices and technologies designed to slow down, detain, soak up and re-use stormwater. At TRCA, these practices are investigated under the Sustainable Technologies Evaluation Program (STEP), a multi-agency initiative. STEP provides the data, technical guidance and practical tools needed to support broader implementation of sustainable technologies and practices within a Canadian context. Among other things, STEP:
- monitors and evaluates clean water, air and energy technologies;
- assesses the barriers and opportunities to implementing these technologies;
- develops tools, guidelines and policies; and
- promotes the wider use of effective technologies through research, education and advocacy.
In 2012, based on research conducted by STEP, the Living City Campus at Kortright was recognized under the Canadian Environmental Technology Verification Program as Canada’s testing and verification centre for stormwater and renewable energy technologies.
Permeable pavements and bioretention cells are two stormwater management practices designed to reduce runoff from driveways, parking lots, patios, walkways and roads. These and other Low Impact Development (LID) stormwater practices have been constructed as part of TRCA’s Green Parking Demonstration at the Living City Campus. This demonstration is the first Canadian research project that addresses many of the common concerns about LID stormwater practices, including their performance during winter conditions, construction costs and long-term inspection and maintenance needs. Three different permeable pavements were assessed by TRCA staff from 2010 to 2012 to determine their effectiveness, both financially and technically, in meeting the stormwater management and green building challenges of urban development.
In 2012, TRCA received a grant from the Ontario Ministry of the Environment and in-kind donations from Ontario Tire Stewardship, IOWAT, Eco-Flex, ThermaGreen, EMCO, Terrafix, and Schollen & Company to support the second phase of the project. A second bay of the Kortright Centre parking lot was renovated to feature composite permeable pavers made from recycled rubber tires. In addition to reducing the number of tires sent to landfill, these pavers require less energy to produce and weigh less than concrete pavers. Half of the bay showcases permeable composite pavers by AZEK Building Products and the other half, non-permeable composite pavers by Eco-Flex.
The non-permeable paver section drains to two bioretention cells located in the tree-lined islands that are a distinctive feature of the parking lot. The side-by-side cells allow comparison of the contaminant load reduction benefits of the two designs.
“The goal is to showcase a more sustainable way to manage stormwater. We are trying to both reduce the volume of runoff and improve the quality,” says Dean Young, Project Manager, Sustainable Technologies, TRCA. “Even when installed on low permeability, clayey soils like those common in Southern Ontario, permeable pavement produces about 43 percent less runoff than a conventional asphalt surface. Most contaminants typically found in urban runoff are trapped as it filters through permeable pavement and the underlying soil. We have found that heavy metal loads are being reduced by 80 to 90 percent compared to a conventional parking lot.”
For more info about STEP’s permeable pavements project, visit: http://sustainabletechnologies.ca
As our climate warms, changing weather patterns are affecting stream flow, the distribution of flora and fauna, the types of vegetation that adapt in ecological restoration efforts, and the demand for water by agriculture and other large scale users. Climate change will also result in a greater intensity and frequency of heavy rain events, as well as a seasonal shift in heavy rains to periods when the ground is already saturated or frozen. These factors must be considered when planning for the long-term health of a watershed, its natural features, flora and fauna, and the people who live there.
TRCA completed the Petticoat Creek Watershed Action Plan in 2012 and published the Plan in the spring of 2013. The Plan will help guide governments at all levels to make decisions based on sound science that support healthy ecosystems. The Petticoat Creek river system is 49 kilometres long, with rural lands dominating the northern portion and urban development in the south. The watershed includes lands in Toronto, Markham and Pickering, and is home to some 25,000 people. It also includes such recreational amenities as Rouge National Urban Park, Altona Forest and Petticoat Creek Conservation Area.
It has been more than five decades since the last plan for Petticoat Creek watershed was done. Obviously, the land uses in the area have changed significantly during that time, and an assessment of the watershed’s current health was needed in order to plan its future. This plan includes a summary of the state of the watershed, and recommendations about how to maintain its health, and to make improvements where needed,
Adele Freeman, the Director of Watershed Management at TRCA
While only the southern 20 per cent of the watershed is urbanized, the density and type of development have had significant negative impacts, including changes to how water moves above and below ground, and a reduction in natural vegetation cover. The ecosystems in the watershed are currently in “fair” health, but more attention is needed to prevent further degradation.
Fortunately, the watershed is well-positioned to respond favourably to remediation efforts. Unlike its neighbouring watersheds, whose sources lie in the Oak Ridges Moraine, most of the flow in Petticoat Creek comes from surface water. This means that stormwater management and runoff control practices can have significant positive effects on the stream.
The Petticoat Creek Watershed Action Plan, including recommendations and the next steps for implementation, is posted on-line at http://trca.on.ca/the-living-city/watersheds/petticoat/, and is also available at public libraries in Scarborough, Pickering and Markham.