Residents living near Burnco’s proposed expansion of its Cochrane West gravel mine are raising concerns the expansion might jeopardize the local water table and lead to greater contamination of the Bow River.
According to Darryl Cornish, whose property is 800 metres from the mine and who has 18 years experience working as an engineer for Schlumberger, a well-known international reservoir measurement, analysis, and modelling company, Burnco’s own Impact Assessments, prepared by Matrix Solutions, show there are several causes for concern.
Cornish requested and received the Impact Assessment report from Rocky View County, and provided a summary of it for Great West Media.
“First let me note that I am both pro-development and a supporter of responsible aggregate mining,” Cornish said in a statement to Great West Media. “I followed Burnco’s initial applications for the Cochrane West aggregate mine and I was impressed by the measured approach taken by Rocky View’s Council. When the Council approved the one quarter section expansion to the existing mine with significant caveats, I elected not to oppose it because it appeared that the Council understood the significant risks associated with gravel along the banks of the Bow River, and especially the risks associated with mining gravel below the water table. As a result of this trust in the wisdom of the Council, I had ignored Burnco’s further efforts until I was informed a few months ago that the Alberta Ministry of Environment and Protected Areas (MEPA) has approved de-watering six kilometres along the banks of the Bow River based on Impact Assessments from Matrix Solutions.”
De-watering refers to the practice of removing groundwater to more easily access the gravel underneath.
“The Matrix Impact Assessments, commissioned by Burnco, purport to support Burnco’s recent Master Site Development Plan (dated July 2024) to expand their gravel mining operations West to Beaupree Creek,” said Cornish. “The Matrix Assessments actually do identify significant issues with both the expansion and the analysis that Matrix provides.”
Cornish goes on to detail several of his concerns, which he will present at a forthcoming Rocky View County public hearing on Dec. 3.
“The MEPA approval allows Burnco to de-water the existing gravel aquifers and remove that gravel down to the underlying fractured bedrock,” he stated. “This process will destroy multiple gravel aquifers that filter and restrict groundwater entering the Bow, while at the same time freeing and mobilizing a large number of contaminants. The Matrix Assessments, and Burnco’s own monitoring data illustrate that this is a very real concern that is being ignored by Burnco, Matrix, and sadly by MEPA as well.”
Cornish explained this point further in a follow up phone interview.
“So basically, where they're mining for the gravel is along the ancient riverbed of the river,” he stated. “When the time at the time of the last stage was about a mile and a half wide, and they're taking it right from the banks of that little river, and they're taking out all of the gravel that forms all of the aquifers along that. So they're taking out, you know, let's say between 30 and 50 feet of gravel. And the bottom, probably 15 to 20 feet of that is in the aquifer. So they're taking out all of that gravel. And then what happens is the water throughout the aquifer trying to fill a hole back in.”
Cornish said for comparison purposes a calf-cow operation with 50 animals would use about 1,200 gallons a day. What Burnco is proposing would remove perhaps as much as ten times that amount on a daily basis.
“So, you know, the amount of water draining out of the aquifers dwarfs any landowners draw on the aquifer by comparison,” he said.
Chief among Cornish’s concerns is the potential for heavy metal contamination into the Bow River from crushing rocks at the proposed mining site due to hydrological conductivity, or leaching, from the pit into the nearby river.
“There's definitely the potential for water to flow through that heavily fractured bedrock into the river,” he said.
Cornish explained his concerns with Burnco’s own internal assessments which led to his fear the potential for leaching has not fully been accounted for.
“The authors of the Assessments understood that Burnco’s intent was to crush the rock, releasing those heavy metals,” Cornish stated. “To further complicate this, some are moraine deposits with little water movement/modification (fluvial), some are heavily water modified, with variations everywhere in between. Both moraine and fluvial deposits form channels. The geochemical composition of these channels can vary dramatically even over short distances requiring a large number of sample boreholes to accurately characterize the average heavy metal content prior to approval. The heavy metal content of the rock in even the limited number of boreholes drilled was not evaluated or considered in the study.”
Residents opposed to the mine expansion commissioned percolation tests, said Cornish, which spoke specifically to these concerns. Tests which seem to have been dismissed by Burnco and MEPA.
“Percolation tests on two samples of crushed gravel from the existing mine, performed by Dr. Jon Fennell funded by residents, both showed levels of heavy metals above limits for introduction to ground or surface water,” explained Cornish. “Dr. Fennell’s results were not considered of interest by Burnco or MEPA. Burnco’s own monitor wells indicate that total dissolved solids (TDS) are increasing in the groundwater between the mine and the Bow River. TDS is a proxy for heavy metal contamination, but the (Burnco) Hydrology Assessment lists very few tests done to determine the extent of this contamination and its variability across the site.”
Cornish said he is extremely concerned about the proposed gravel mine expansion in Cochrane West, and he encouraged Rocky View councillors and residents to step up to protect their own interests.
“Both Burnco’s results and those of Dr. Fennell prove there are toxic heavy metals in the rock being crushed,” he said. “The total dissolved solids (TDS) in groundwater downgradient of the mine are increasing. In an environment where heavy metals are entrained in the rock being crushed, an increase in TDS is a proxy for an increase in heavy metals.
“It is my opinion that the environmental assessments provided by Burnco are wholly insufficient to justify the risk to the environment that the proposed gravel operations present, and the process that has led to this hearing is not balanced, fair, or appropriate for a decision of such magnitude,” he stated.
Great West Media reached out to both Burnco and the Alberta Ministry of Environment and Protected Areas to get their comments on Cornish’s concerns, but they had not responded prior to press time on Wednesday.
The public hearing for the proposed Burnco Cochrane West expansion is on Dec. 3 in Rocky View County council chambers, or can be followed online live at www.rockyview.ca/meetings-hearings.
-With notes from Riley Stovka/ Great West Media
