The water usage required to support the proposed Melville Pit raises significant concerns regarding water quality and quantity impacts for nearby properties dependent upon individual wells and groundwater. It also has the potential to adversely impact two municipal wells that serve the Town of Orangeville.

Water Quantity

Any activity that takes water from an aquifer, without returning the water to that aquifer is a threat if it results in a depletion of available supply which could impair the long-term viability of a water system. The province establishes thresholds, to protect the ecosystem and other users, to determine if the water taking is sustainable. Municipal and private wells are typical examples of such water taking activities, along with industrial uses such as agriculture irrigation and aggregate extraction.

The Hydrological Cycle
The Hydrological Cycle

The proposed Melville pit will use water for washing of aggregate and dust suppression. This water will come from a supply pond which will be dug to the size of 80 m x 50 m x 7 m = 28,000 cubic meters, or the equivalent of 11 Olympic swimming pools. Half of the aggregate would be washed onsite which is equal to 600,000 per year. While the main processing plant is operating it will use 303 liters per second, hence 13.1 million liters per day or 72 m liters per week. This is a huge amount of water, and is more than the weekly water used by the entire town of Orangeville (61.4 million liters in 2012).

It is important to understand that 85% to 90% of the water that is used for washing the aggregate will be recycled back through the supply pond system or will filtrate back into the ground and so 10% to 15% of the water will evaporate or adhere to aggregate being shipped off-site. Since up to 15% of the water is consumed (lost) during operation this equals 43 liters per second, or 2 million liters per day or 10.8 m liters per week, and since the pit would be operated from June to November, or 143 working days, the operation will consume 75 million liters of water per year. Importantly these figures do not include the water required fro dust suppression or to support Olympia Sand and Gravel Ltd.’s amended application to include aggregate recycling on this site.

CAMP engaged Doctor Ken W. F. Howard, an internationally recognized hydrology expert, who is a Groundwater Consultant and University Professor to review the water consumption data submitted by Olympia Sand and Gravel Ltd. in support of their application. Dr. Howard has no issue with the aquifer parameters being used by the applicant’s consultant AECOM. However as a result of the amount of water taking being requested, Dr. Howard concludes that the supply pond will not be able to provide enough water for the proposed extraction and is likely to go dry within just a few weeks. Dr. Howard considers the water table aquifer beneath the deposit to be weak (thin and poorly permeable) to the extent that the water required for on-site processing, mostly aggregate washing, will be extremely difficult, if not impossible, to obtain. Dr. Howard concludes that ..”the water needs for the operation cannot be met by the aquifer”

Olympia Sand and Gravel Ltd.’s application for a permit to take water has received considerable push back from the Ministry of Natural Resources and Credit Valley Conservation Authority. Since Dr. Howard’s report has been shared with the applicant they have stated that they would reduce further their production and that the washing would take less liters per second too. Yet even with these their water consultant AECOM and the Town of Caledon’s peer reviewer, Consulting Hydrologist Bill Blackport, agree that the supply water pond could go dry up “within a week of operation”.

This water constraint raises concerns about the extent to which this pit operation, if approved would impact the water table and surrounding wells in the area, including two municipal wells serving the Town of Orangeville (see Implications for Orangeville). Also beyond the impact to wells a further indication of the potential offsite impacts can be seen in the Credit Valley Conservation file # R26/CA/05/Olympia April 2 2012 that “water values are high enough to justify concerns about impacts on nearby ecological groundwater receptors”.

Water Quality

We are also concerned about potential water quality impact resulting from the Melville pit. The Ontario Stone, Sand and Gravel Association commissioned Golder and Associates Ltd to prepare a technical report for the recently completed Standing Committee’s review of the Aggregate Resources Act. The report, titled “Cumulative Impacts for Groundwater Takings in the Carden Plain Area (September 2012) noted quarry operation already increase concentrations of boron, iron, sulphate and chloride as a result of de-watering groundwater from quarries.” The potential threat to residential water resources represented by the recycling of aggregate materials also needs to be better understood.

In Summary

While we acknowledge that further subsurface testing will be completed as part of the Permit To Take Water (PTTW) application to the Ministry of the Environment as part of the Ontario Water Resource Act, we believe that the Town of Caledon has failed in their responsibility to fully evaluate these issues now. Given what is at stake, these issues require independent, transparent analyses before any further approval is given for the mining operation.