To determine composition of reflection patterns determined by the GPR a vibra-core device was used. A vibra-core device can be used to extract sediment cores. Sediment cores were retrieved using a vibra-corer (below) that was used during the winter when ice created a solid platform from which to work from. The aluminum irrigation pipes were vibrated into the sediment using a cement vibrator.
Vibra-coring on HML. The vibra-core consisted of a cement vibrator and aluminum irrigation tube.
Based on radar stratgraphic analysis of the transects, areas with distinct reflection patters were noted for vibra-core exploration. At these locations the vibra-core was used to ground truth the GPR transects. At all of the vibra-core locations field notes containing location, sediment thickness and composition of lake bottom (bedrock or gravel) were noted. Ground truthing was compared to GPR transects confirm depth and boundaries of the industrial organic waste. Two cores, HMLVC1 and HMVCL2 were extracted for further analysis at the LaCore facilities at the University of Minnesota.
At the LaCore facilities at the University of Minnesota cores were split by scoring the aluminum pipe and using piano wire to cut the core. The cores were then described by texture and color Magnetic susceptibility and density measurements were also conducted but are not relevant for this study.