Grant: Alliance Grants

Quarry and other large-scale landscape modification operations involve excavation and removal of earth material that when otherwise left intact provides natural protection against groundwater pollution. Thus, when a quarry is deepened, it is critical to investigate the impact on the groundwater system. This is particularly true when the material being excavated is fractured rocks that by their nature are more prone to contamination because these fractures can act as a direct connection between the surface and groundwater. Thus, landscape modifications can greatly affect groundwater quality and therefore, there is a global need to understand these impacts. In this context, the Dolime Quarry represents an ideal research site to further scientific understanding of this problem. This quarry is located within 2.5 km of 8 active municipal water supply wells in Guelph (pop. 135,000), and excavations have breached the main aquitard (a low permeability geological formation) that protects the city's primary water supply aquifer. This breach makes the city's water supply vulnerable to pathogens, viruses or other contaminants if not appropriately managed. The city is proposing to take control of the quarry dewatering operation to manage this threat, but careful measurement, monitoring, and testing programs are needed to mitigate future contamination risks. To address this problem, the study requires datasets of higher spatiotemporal resolution than possible with conventional approaches. The research will deploy state-of-the-science sensor technologies to measure near-quarry hydraulic responses, define geological and hydrogeological units, identify aquitards, and investigate possible interactions between surface water and groundwater. This research provides robust data to understand the risks all major quarries pose to groundwater and guidance on how to best manage these risks long-term in communities across Canada, where more than 3000 quarries actively impact local groundwater systems. Moreover, findings from the application of innovative tools and approaches are transferrable to other global communities that rely on fractured rock aquifers for clean drinking water, agricultural and industrial use.