An apparatus for collecting upward-looking GPR surveys in potash mines

GPR has been used routinely in Saskatchewan, Canada, potash mines for nearly forty years. In general, the purpose of GPR surveys in potash mines is to map the salt-bed stratigraphy above and below the mined-out rooms. The stratigraphy in the Saskatoon, Saskatchewan area mines consists of a series of salt and potash beds separated by well-known and regionally distributed planar clay seams. The salt-beds have very low electrical conductivity, which makes GPR highly effective for imaging the clay seams. Collecting downward-looking GPR data in potash mines is straightforward, as the mine personnel can use standard off-the-shelf GPR equipment (push carts for example). Successful and safe collection of upward-looking GPR data is considerably more challenging. The terrain is uneven, there are numerous obstacles, and room heights are quite variable. Typical Saskatchewan potash mines are very large, with 100s of kilometers of operational mine rooms, so a solution which permits seamless collection of upward-looking GPR data was needed. This paper presents the evolution of various apparatus used for collecting upward-looking GPR data in potash mines. The work eventually led to the development of a Kubota RTV mounted light-weight floating lift. This apparatus is known as a GPR-RTV, and it successfully overcame the many challenges to routine upward-looking GPR data collection in potash mines. Some data examples are presented to illustrate the effectiveness of the GPR-RTV. Finally, although this discussion focuses on applications in potash mines, it is envisioned that the GPR-RTV could be used safely in a variety of conventional mining and tunneling environments.