Do the impacts of aggregate extraction below the water table increase when the number of such operations in a given area also increases?

This is one of the issues that a report about the cumulative impacts of aggregate extraction below the water table in the Grand River watershed is seeking to determine. The answers might be of extra interest to residents of Woolwich, where five new gravel pit applications are under review.

Entitled “Cumulative Effects Assessment Best Practices Paper for Below Water Table Aggregate Operations within the Grand River Watershed,” the report comes after a number of municipalities in the watershed raised concerns about the cumulative impacts of the growing number of aggregate operations in their jurisdictions.

The report outlines steps that should be taken to identify the potential effects on surface and groundwater quantity and quality as a result of several gravel pits operating close to one another.

The study comes after several municipalities within the watershed questioned whether the presence of several pits operating below the water table could affect the quality and quantity of surface and groundwater downstream from the operations. Would the cumulative impact of these pits – all in relative proximity to one another – increase as the number of pits increased? Does the excavation of several pits affect the overall level of the water table? Does it affect the potential for wells and springs to draw on those sources? From a quality perspective: do the sub-water table pits provide a pathway for contaminants to infiltrate the water table?

While those issues are addressed every time an individual application for a gravel pit operation is made, a holistic approach to the cumulative effects of several pits, remains to be made, suggests the Grand River Conservation Authority, which is undertaking the study.

“We want to take a broader look at it. Say you’ve got four or five gravel pits in a fairly small area: do they have an impact that is greater than the sum of the individual pits?” said spokesman Dave Schultz.

A copy of the study report, which was prepared by representatives of the Grand River Conservation Authority, the Ontario Ministry of Natural Resources and the Ontario Sand Stone and Gravel Association is available on the GRCA website at www.grandriver.ca. Comments can be sent by e-mail to policy@grandriver.ca by July 31.