MONITORING THE HYDROLOGY OF AN EXPERIMENTAL WASTE ROCK PILE USING FIBER-OPTIC DISTRIBUTED TEMPERATURE SENSING
The experimental waste rock pile is 60 m long (with an additional 5.3 m toe) and is 32 m wide. The pile has a maximum and minimum thickness of 7 m and 4 m respectively, for a surface inclination of 5%. The coarse grained waste rock is covered by a 1 m thick compacted finer-grained layer: 75 cm of sand over 25 cm of non-reactive crushed waste rock. The pile is underlain by six lysimeters that capture water that flows through the pile. At three layers (at the base, just below the cover, and in the cover) there is approximately 500 m of fiber-optic cable laid in a grid pattern per layer. The system utilizes ‘hot’ FO-DTS, whereby the cable is doubled (i.e. the cable runs parallel to itself) and half of the cable can be heated and the thermal response of the unheated cable is used to evaluate moisture content and fluxes. The system has a horizontal spatial resolution of 0.5 m and temporal resolution of 20-40 seconds. The experimental pile will be briefly described, and initial FO-DTS results from in-situ measurements will be presented. The presentation will illustrate how temperature is used to sense the internal hydrology of the pile, including comparisons to moisture sensors and lysimeter fluxes. Additionally, results will be presented from an artificial infiltration tests that tests the pile’s ability to inhibit infiltration.