Investigation into the Implications of Geothermal Heating and Cooling Use on Soil Organic Carbon Decomposition and Contaminant Mobilization

This professional project paper investigates the long-term impact of ground source heat pump (GSHP) operation using a helical steel pile heat exchanger (HSP) on soil organic carbon (SOC) decomposition, as well as the mobilization of benzene and toluene. A computational fluid dynamics (CFD) model was developed based on an 8-HSP system installed at the Eby Rush Transformer Station in Waterloo, Ontario. This model was validated using experimental data and simplified to conduct 20-year heat transfer simulations under a thermally unbalanced load, enabling the calculation of soil temperature change over time. This data was utilized to determine the change in SOC decomposition and the sorption coefficient of benzene and toluene. The results of the study indicate a rise in soil temperature after 20 years of operation which has a significant effect on SOC decomposition rate, but a negligible impact on the mobilization of benzene and toluene.