It is my opinion that the…

It is my opinion that the application of Lafarge Canada Inc. (LaFarge) to increase its water-taking permit (which is equivalent to 46% of the total average daily water takings of the City of Guelph) and continue the mining of the City of Guelph’s bedrock aquifer is not in the best interest of the residents of Guelph.

Quarries inevitably disrupt the existing movement of surface water and groundwater and can lead to reduced quantity and quality of drinking water for both residents and wildlife near or down stream from a quarry site (Castrilli, 2005; Ekmekci, 1990). LaFarge has been quarrying the overburden sediments and plans to quarry the subsequent dolostone bedrock which act as a protective cover for the underlying aquifer, two major changes may occur in the hydrogeological system related to water quality and the flow system which pose a threat to the safety of the City of Guelph’s drinking water.

Two papers (Castrilli, 2005; Ekmekci, 1990) show that where the water table of a flooded fractured bedrock aquifer is near the surface, removal of the overburden and limestone cover leads to increased risk of contamination. The scar created by a quarry may easily act as a conduit for contaminated surface runoff (OSSGA, 2010) to enter the otherwise confined and protected bedrock aquifer. This can rapidly introduce road salt runoff, agricultural runoff, or industrial runoff which can degrade the water quality and make the water unsuitable for human consumption. Quarries located close to towns and cities such as the LaFarge quarry may become a source of pollution for springs that emerge downstream.

The other impact of a quarry is that blasting and pumping can result in the destruction or disruption of groundwater flow paths, changes in the pattern of groundwater movement and changes in the quantity of water flowing through the fracture system. This sudden change in groundwater flow can result in significant decreases to the amount of water abstracted from pumping wells fed by the aquifer (Ekmekci, 1990). A paper written by the Ontario Stone, Sand & Gravel Association (OSSGA, 2010) confirmed that the act of dewatering in a quarry usually does affect groundwater levels and flow patterns around the site since it artificially lowers the water table to at least the base of the quarry. The resulting drawdown cone or radius of influence can result in nearby wells, wetlands, and streams going dry. Therefore, it is critically important for the wells, streams, wetlands, and other sensitive features within the radius of influence to be carefully and thoroughly studied in order to be able to accurately predict the impacts and devise mitigation measures. The implementation of a groundwater monitoring program is extremely valuable in order to measure the influence that the quarry is having on the surrounding environment.

Furthermore, it can be seen that the LaFarge quarry operates within the 2 year capture zone of the Southwest Quadrant Municipal pumping wells as seen in the 2010 Groundwater-Surface Water Vulnerability Report (City of Guelph, 2010). This suggests that the LaFarge quarry is in a extremely hydrogeologically sensitive location and extensive studies must be done in order to determine whether the activities conducted at this mine pose a direct threat to the City of Guelph’s Municipal pumping wells.

In conclusion, the effect of aggregate and dolostone quarrying and resulting dewatering can have an impact of greater magnitude and extent that almost any other human activity on the planet. This change may be concentrated within a small area compared to the extent of the aquifer, but its negative effects on the quality and quantity of the groundwater resource potential can extend further.

References

Castrilli, J. Application to the Lieutenant Governor in Council regarding Dufferin Aggregates application to expand their Milton Quarry prepared for Coalition on the Niagara Escarpment (CONE) and Protect Our Water and Environmental Resources (POWER). 2005.

Ekmekci, M. E. H. M. E. T. (1990). Impact of quarries on karst groundwater systems. IAHS PUBLICATION, 3-3.

Winfield, M and A. Taylor. Rebalancing the Load: The need for an aggregates conservation strategy for Ontario, 2005. The Pembina Institute, pgs 8-9.

(OSSGA, 2010)
https://www.ossga.com/multimedia/9/groundwater2010.pdf

(City of Guelph, 2010)
https://guelph.ca/wp-content/uploads/2010GroundwaterSurfaceWaterVulnera…