New Gravel Resources Information Will Help Reduce Construction Costs in Canada’s North

By Kristin Anderson

November 2010

Crushed, clean granular aggregate (“Loonie” for scale)

Construction costs in Canada’s North could soon be reduced significantly, thanks to new information about local and regional gravel resources. Rod Smith, a research scientist with Natural Resources Canada’s (NRCan’s) Geological Survey of Canada (GSC), has constructed a database and geographic information system (GIS) based on a never-before used source of geological data — seismic shothole drillers’ logs — that can help identify potential gravel deposits throughout the Northwest Territories and northern Yukon.

Worth millions of dollars, this information will help communities and the territorial governments by reducing the cost of trucking in gravel from distant sources.

This new approach is also particularly timely, given the prospective development reports for an all-season road — connecting the Mackenzie Valley from Wrigley north to Inuvik and then on to Tuktoyaktuk — that was announced earlier this year by the Canadian Northern Economic Development Agency (CanNor) and the Government of the Northwest Territories.

Seismic Shothole Records Providing Important Data

Rod Smith inspecting an exposed section of gravel in an active gravel pit in northern British Columbia.

Seismic shotholes are drilled 10–60 m into the ground during geophysical seismic exploration, and the drillers log the soil and rock layers they find. Over the past five years, Rod has been collecting and analyzing the industry’s archival logs for northern Yukon and the Northwest Territories. His database now includes over 275,000 records, with another 70,000 to go, and presents a vast new source of unrivalled baseline information on gravel sources and much other geoscience information. This data and its potential uses are of great practical importance.

“Gravel is the largest amount of material mined in Canada, with the exception of the oil sands, and is critical for the development of transportation infrastructure, residential areas and industrial facilities,” says Rod.

Because the Northwest Territories is so vast, any new large-scale development proposal — such as the completion of the Mackenzie Valley Highway — faces enormous costs simply for trucking in the basic construction material gravel from remote deposits.

The Trout Lake Example

The gravel publications display for the Trout Lake area on a Geographic Information System (GIS).

Consider the case of the small community of Trout Lake, close to the Northwest Territories’ southern border with British Columbia. “Before 2006, gravel was trucked in from a site over 100 kilometres away at a cost of $265 per cubic metre,” notes Rod. “A gravel pad for a typical fourplex home requires 675 cubic metres of unsorted aggregate and 200 cubic metres of sorted aggregate — which can add up to $200,000 of granular material before even starting to build the house.”

With the high cost of shipping, and the logistical challenges of seasonal winter road access, isolated communities have been forced to pay a premium for infrastructure projects.

The new database will solve this problem and greatly reduce the cost of transporting gravel to northern communities by identifying new, closer gravel deposits. In the case of Trout Lake, the drillers’ log records confirmed a new site only 15 km away, resulting in lowering the costs to $110 per cubic metre.

“For larger regional infrastructure projects, companies could potentially cut construction costs by hundreds of millions of dollars,” says Rod.

To download, free of charge, the NWT report and the Yukon report, visit NRCan's GeoPub Web Site.

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