A Canadian geophysical survey firm is mapping the results of its projects within minutes after collecting the raw data. The technicians use Surfer to conduct initial data interpretation and generate an easily understood georeferenced PDF map for digital delivery to their clients while everyone is still on the project site.
“We do mapping on a laptop right in our truck,” said Brandon White, President of Cascade Imaging Solutions Inc. “The clients want the results right away, and we need to know we’ve surveyed the entire area.”
Based in Edmonton, Alberta, the geophysical firm uses frequency domain electromagnetic devices to measure the conductivity of the Earth. Specifically, they are looking for ionic compounds, such as salts, that indicate underground contamination from oil & gas, agriculture, and road maintenance operations.
High conductivity measurements correspond with abnormally high concentrations of subsurface salts, possibly related to leaks or spills of petroleum emulsions, fertilizers, livestock waste or road deicing chemicals.
“We use Surfer to image the data, producing a color contour map showing where the contamination is,” said White. “It’s usually a color-scale heat map [where] red means higher conductivity, or contamination.”
Soil conductivity is measured in milli-siemens, but the scale is not absolute. Every site has some natural conductivity based on its physical and chemical properties. This means Cascade Imaging technicians must first examine the raw data in Surfer to determine the natural conductivity level of the area. Once this is determined, they can establish a relative conductivity scale in Surfer and generate the contour map showing locations of anomalies.
The results could be mapped with GIS software, White said, but the expensive package he tested was too cumbersome to use, involving too many steps for simple importing and exporting of data. And the results weren’t as visually impressive as those generated in Surfer. He added that it’s also quick and easy to teach new technicians how to use Surfer.
An enormous advantage for Cascade Imaging in the latest version of Surfer is its ability to handle and output georeferenced data. The conductivity measuring devices used by the Edmonton firm are linked to a GPS which tags each point with x, y and z coordinates. Once the contour maps have been made, Surfer retains the georeferencing and outputs the results in geo-PDF format.
“We can email the PDF right to the client’s smart phone [onsite] so they can figure out where the contamination is relative to where they are standing,” said White.
Back at the office, Cascade technicians massage the data in Surfer to generate high-quality contour maps as final deliverables to the client. Often, the contour map is overlaid on a digital elevation layer or air photo to provide additional perspective. Once the contamination map is completed and delivered, the client typically uses the information to drill into the site to confirm the presence, concentration and depth of the pollutant.