Grant: Discovery Grants Program - Individual

The objective of my research program is to develop new methods of quantifying and remediating thermal impacts from below-water-table aggregate and rock extraction on cool-water streams. The focus will be on remedial methods that utilize the aquifer thermal energy generated from the water filled extraction pits for heating and cooling local buildings and neighbourhoods. In this way not only will cool-water ecosystems and fisheries be protected adjacent to extraction sites but the remedial systems will provide a sustainable energy source. Currently, we are nearing completion of an unprecedented 10 year field and numerical modelling assessment to quantify the persistence of thermal plumes emanating from an aggregate pit through an unconfined, glacial outwash aquifer. Our results show that alternating warm and cool plumes persist in the aquifer for 11 months, migrate up to 250 m down gradient, and if sufficient separation distances are not provided, temperature changes of even 2 to 3 degrees C in the hyporheic zone may adversely affect the macroinvertebrate community and incumbent brook trout populations. ) ) The approach will be to continue the development, verification and field validation of our finite-element numerical model to properly represent groundwater - surface water interactions. A set of simplified and cost effective numerical / analytical tools for guiding investigations of pit-aquifer-stream operational and risk assessments will be developed and tested at our field site. Our field validated numerical model will then be used to design and test various shallow aquifer thermal energy extraction and utilization techniques. Given the seasonal cool and warm water plumes emanating from the pits, proper placement of the system could yield both increased thermal heating in the winter and increased thermal cooling in the summer, over conventional low-temperature geothermal systems where groundwater is close to the mean annual air temperature. Where utilizing the thermal energy is not cost effective, alternative remedial measures that increase the travel time / distance to cool-water streams, or passive techniques that reduce thermal plume peaks, will be developed.