senseFly’s latest case study tells the story of a challenging contamination mapping project in the High Arctic. BluMetric Environmental was contracted to perform environmental assessments in the Canadian territory of Nunavut, but faced a challenge in the form of low-quality topographic maps of the region. The solution? Employ a senseFly eBee drone to produce the high-resolution, high-accuracy digital terrain models its team required.
Nunavut is Canada’s most northern and least populated territory, comprising most of the Canadian Arctic Archipelago. It is also a region that includes industrial activity, resulting in areas of hydrocarbon contamination, many of the operators having long since ceased operations. In the summer of 2015, the federal government contracted consultants BluMetric Environmental Inc. to assess and document several sites of suspected contamination as a way to reduce the impact of this contamination on the region’s ecosystem.
Measuring the mess
The job of BluMetric’s team, operating out of the Eureka Weather station and at Rae Point on Melville Island, was to spend a significant number of man hours sampling and fully characterising each site.
Our environmental engineers had to quantify what was contaminated and calculate the exact volumes of each contamination zone
“Our environmental engineers had to quantify what was contaminated and calculate the exact volumes of each contamination zone, before reporting back with estimates on how much it would cost to clean up these areas should the government choose to move to remediation,” says BluMetric’s geomatics manager, Yannick Lanthier.
Cost-effective data capture
BlueMetric’s eBee mapping drone came into play in aerially surveying the six sites. “We have used the eBee since it was launched in 2012 when we were looking for a full, one-package deal that included a safe, easy-to-use UAV and software,” Lanthier states. “We wanted a 99% automated tool to reduce the chance of user error. We have since purchased a second eBee due to demand from the aggregate sector continuing to increase.”
Satellite images would have been significantly lower resolution than the drone’s photos. Plus, they would have been very expensive.
Why use a UAV and not existing topographic maps or alternative data sources? “The topos available of the area, at 1:50,000, are not at all precise enough for the work required,” Lanthier says. “Satellite imagery might have been an option for creating our models, but these images would have still been significantly lower resolution than the drone’s photos, maybe 50 centimetres per pixel compared to the four centimetres we achieved with the eBee. Plus, they would have been very expensive, at around 2,000 US dollars each and we still wouldn’t have detailed topography. So it made more sense to check the drone with our luggage and collect our own aerial data, since we had to go on site to survey the sampled locations with the environmental team.”
Alongside its mapping drone, Lanthier’s staff also used an RTK GPS to control the models it created, employing white reusable markers as ground control points to achieve an absolutely digital model accuracy of down to 1-2 cm.
Putting the data to work
Having created six drone-sourced digital terrain models, BluMetric then employed these outputs to guide its sampling. “For example, we might use a DEM to perform a surface flow analysis, in order to model where diesel oil would have flowed had there had been spillage from a drum,” Lanthier explains.
The key benefit of the UAV was the ability to capture high-resolution imagery over the vast site area and to be able to carefully review the resulting orthomosaic on the screen to find extended contaminated zones
“The key benefit of the UAV was definitely the ability to capture high-resolution imagery over the vast site area and to be able to carefully review the resulting orthomosaic on the screen to find extended contaminated zones,” Lanthier concludes. “Being in the Arctic, even some impacted soil from the 1970’s will still show a scar, such as weak or no vegetation and/or disturbed native materials. We can’t walk the entire eight square kilometres to find every source of contamination, nor fly the crew over the area in a helicopter as this would be more expensive on fuel. Using the ortho, we were successfully able to locate other minor impacted soil and could concentrate our efforts on investigating these areas very cost effectively.”