You might think that a firm that specializes in “Creating Space Underground” wouldn’t have much use for a drone that captures images of features that are above ground. On the contrary, Abandoned Mine Land (AML) subsidence investigation and mitigation is a successful niche market for Brierley Associates, and drones help in myriad ways to identify and solve our clients’ subsidence challenges. We now have four professionals–engineers, geologists and GIS analysts–who hold FAA Part 107 Drone Licenses.
Our Matrice 210 RTK drone is equipped with a Zeiss 5X Zenmuse camera and gimbal system that produces superior video footage and provides our clients with the ability to see objects at various angles with high resolution. Real Time Kinematic (RTK) capability relies on global positioning systems (GPS) to perform accurate survey with less effort and shorter time. This really comes into play when our AML team is identifying land depressions in remote and expansive areas that might be evidentiary of subsidence risk. With high-resolution imagery collection and Drone2Map analysis, finding these features is easier than relying on conventional ground observations. Additionally, drone technology lets our AML team members capture surface features within large tracts of land or in difficult access places, such as exposed rock walls or other steep terrain.
As with most projects that require surface (and underground) analysis, GPS reconnaissance and control point (GCP) collection is essential to geographically locate subsidence features such as sinkholes. Post processing of imagery and data allows us to produce digital orthophoto mosaics using corrected GPS points and we can achieve imagery accuracy in the 2-3 cm range. This enables our AML and GIS team to produce Digital Elevation Models (DEM) and contour lines that help us identify evidence of potential subsurface void space.
Brierley’s GIS specialists routinely incorporate survey grade GPS points with high-resolution drone imagery to create useable data sets and mapping. These work products help Abandoned Mine Land agencies make evidence-based decisions relative to course of action options as well as facilitating the creation of agency specific content.
Reliable data has always been key to solving surface and subsurface challenges. Data collected by ever evolving drone technology in the hands of Brierley’s GIS specialists give us the ability see and assess surface features in ways that we never could before.