Canadian Consulting Engineer

Drilling for Information

January 1, 2004
By Sophie Kneisel

It's been almost two years since Ontario's former government announced measures to protect the Oak Ridges Moraine, but many conservationists feel not enough is being done to preserve this important la...

It’s been almost two years since Ontario’s former government announced measures to protect the Oak Ridges Moraine, but many conservationists feel not enough is being done to preserve this important landform. The moraine is home to the headwaters of more than 65 watercourses between the Niagara Escarpment west of Toronto and the Trent River about 100 kilometres east of the city.

At the A.D. Latornell Conservation Symposium held in Alliston, Ontario in mid-November, speakers and attendees expressed concern about issues such as the allocation of water-taking permits, the development of environmentally sensitive areas, and the urban and agricultural pollution of water sources. Despite the obvious importance of the moraine’s water systems, the province appears to have left the job of studying and protecting them to the more proactive conservation authorities.

In 2000, nine conservation authorities formed the Conservation Authorities Moraine Coalition, or CAMC, which collectively owns 10,000 hectares (about five per cent) of the moraine. They agreed on the need for a comprehensive policy, planning and management approach to sustaining the health of the entire area.

The group has developed partnerships with the municipalities of Toronto, York, Peel and Durham, which are funding much of its work. And in what may well be a model of organization for other such coalitions, links have also been formed with various provincial ministry offices and universities. A meeting with the consulting community — to look at how consultants could contribute data and use the database — is being planned for this year.

“We’re trying to extract the best we can out of the key players around the province,” says Steve Holysh, P.Geo., chief hydrogeologist for the coalition, who spoke at the Latornell conference.

The coalition launched a study in its first year that Holysh describes as a “general look” at groundwater studies done in Canada and the U.S. The results were rolled into the second phase of the study, and Holysh was hired to co-ordinate the technical aspects of the work.

The four major thrusts of the project are data collection and management (including amassing information such as 200,000 well records); technical analysis (such as numerical groundwater modelling studies); data acquisition (taking new stream-flow measurements and drilling boreholes for study and monitoring); and finally, using all of this information to create collective policies that are consistent across the moraine.

While the work will help provide benchmarks for measuring the health of the moraine’s watersheds, Holysh feels its more important purpose is to advance understanding of the interaction between groundwater and surface water.

“Understanding how land use changes will affect groundwater systems is vital. We’re making all these land-use decisions without knowing how they impact the hydrologic cycle,” he says. Ultimately, the aim of the studies is to ensure that groundwater stays protected and useable into the future.

Deep drilling

One interesting project in terms of finding new data is the coalition’s plan to drill boreholes down to bedrock and establish as many as 10 monitoring well sites across the moraine. It’s an expensive process, but it’s hard to match from an information-gathering standpoint.

In Toronto’s High Park, for instance, geologists were surprised when a 2,250-litre-per-minute gusher was struck only about 45 metres from the surface. This knowledge helped them map the exact course of the pre-glacial Laurentian River system as it runs under Toronto en route from Georgian Bay to Lake Ontario.

With financial assistance from municipalities, Ontario’s Ministry of the Environment and the Ontario Geological Survey (Ministry of Northern Affairs and Development), the coalition has just completed its fifth drilling project — at a cost of about $50,000 — northeast of Cobourg near Centreton.

Seen against the “brute force” type of drilling used for residential wells, this is a more delicate operation. Steve Davies, P.Geo., the coalition’s senior technical advisor, compares it to diamond drilling. The equipment brings up 1.5-metre lengths of core, which are analyzed and catalogued at the site, and then packaged to be sent to the Geological Survey of Canada’s warehouse in Ottawa.

“We hit bedrock at about 583 feet [175 m], and then cored into it another eight feet [2.4 m],” Davies says. He describes the bedrock as hard, crystalline dolomite. “We found a big, thick sequence of glacial lake clay, which in and of itself is boring, but it’s interesting in terms of [providing information about] the sequence of events that formed the overburden.”

In mid-November, when the drill was at about 130 metres, the moraine till cores looked to the untrained eye like so much grey clay. But it’s the original material laid down by the glacier. “We’re looking at the last 100,000 years of geological time,” Davies says. The ancient water from the bottom of the well will also be studied.

“We have essentially no information about aquifers below 200 feet — the deepest level of most water wells in this area,” says Davies. He explains that aquifers as far down as bedrock have an effect on water at the surface.

The month-long project included spending several days working on a second, shallow monitoring well right beside the first one. Drilled to 45 metres, with monitoring equipment at 15 metres, the second well was created to find out whether there is water in the upper sand formation. Monitoring in the deeper well is being carried out at 175 metres and 110 metres.

“We didn’t encounter a great aquifer,” Davies admits. “But any knowledge is good knowledge.”

In addition to providing geological and geophysical (subsurface structure) information, the well will become part of the provincial groundwater monitoring network. The network was initiated in response to the droughts in the late 1990s by the Ontario Environment Ministry in co-operation with conservation authorities.

The coalition study will officially end in two to three years, but Holysh hopes the work will continue. “The municipalities like what they’re seeing. If we dissolve the partnership, there’s a danger that the database will become outdated and not be maintained. Is the numerical model just going to be a 2002 study, or is it going to continue?”

Sophie Kneisel is a freelance writer living in Baltimore, Ontario and a former editor of Canadian Consulting Engineer magazine.


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