Webinar Series: Van Seters


Ground Source Cooling of Stormwater Pond Outflows: New Research on a Cost and Space Efficient Method to Mitigate the Thermal Impacts of Stormwater Ponds on Aquatic Life


Tim Van Seters and Erik Janssen, Toronto and Region Conservation Authority (TRCA)


Water temperature is a critical component of stream health, as it regulates both biotic and abiotic processes in streams. It can be both the driving and constraining factor for the survival of aquatic organisms.

When runoff is drained through storm water wet ponds, solar radiation heats the open pond water, resulting in thermally enriched outflows that exceed tolerance thresholds of aquatic organisms adapted to cooler water.

Several measures have been devised to help mitigate temperatures and thermal loads from stormwater ponds. These include:

  • Subsurface draw outlets
  • Cooling trenches
  • Night-time release outlets
  • Low impact development techniques

This webinar will provide a contextual overview of several thermal mitigation options monitored and evaluated in Ontario, followed by a more focused discussion of geothermal cooling as a new and innovative approach to addressing the problem of thermally enriched flows from stormwater ponds.

Results discussed are based on temperature and flow monitoring of a pilot geo-cooling system installed at the outlet of a pond in the City of Brampton.

A preliminary decision support tool was developed based on performance data and modelling to assist with sizing and costing of systems for ponds of varying size and outlet characteristics.

The presentation will discuss overall feasibility of the approach along with opportunities for combining the system with other thermal mitigation approaches to optimize system performance and reduce cost.

Learning Objectives

1. Learn about the problem of stormwater thermal enrichment in streams and the various mitigation measures that have been implemented in northern climates.

2. Learn about the application and effectiveness of a geothermal cooling system piloted in the City of Brampton in 2019.

3. Understand how geo-cooling systems can be combined with other practices to optimize overall thermal mitigation performance and reduce system costs.



Tim Van Seters

Tim Van Seters

Tim Van Seters is Manager of the Sustainable Technologies Evaluation Program (STEP) at Toronto and Region Conservation Authority (TRCA).

Tim has more than 19 years of experience designing and implementing field monitoring studies of stormwater management technologies and developing best practice guidance documents on the design, implementation, operation, and maintenance of stormwater practices.

Throughout his career, Tim has presented widely on urban runoff management. and published several reports and papers on urban systems hydrology, watershed water quality, stormwater pond thermal mitigation, and low impact development stormwater management.

Tim holds a Master’s degree specializing in water resources from the University of Waterloo and a Bachelor of Science degree from the University of Toronto.

Erik Janssen

Erik Janssen

Erik Janssen, CMVP (Certified Measurement and Verification Professional), is an Analyst with the Sustainable Technologies Evaluation Program (STEP) at Toronto and Region Conservation Authority (TRCA).

Erik’s work with STEP has focused on the instrumentation, monitoring, and performance analysis of near-to-market heat pump and photovoltaic (PV) technologies. Recent work with STEP includes performance evaluations of geoexchange systems, air-source heat pumps, and gas heat pumps.

Before joining STEP in 2013, Erik was a Laboratory Testing Specialist and Junior Engineer at Ecologix Heating Technologies Inc., a small-scale manufacturer of innovative cold climate air-source heat pumps.

Erik holds an M.A.Sc. in Engineering Physics from McMaster University, a B.Sc. (Hon) in Physics, and a Swedish Magisterexam in Solar Energy Engineering from the European Solar Engineering School (ESES).