Abstract
Cedar North spoil is the first field scale suboxic zone (SOZ) trial performed by Teck Coal Ltd. The objectives of this research program are to construct a trial to assess how suboxic conditions develop with time at field scale, assess how well fine-grained engineered structures limit oxygen ingress and what the longevity of these structures is, and estimate the potential efficacy of in-dump treatment zones to reduce oxidized species like selenate and nitrate to less labile forms. Secondary objectives include assessing & improving the construction methodology, for future applications and assessing the business case for applying source control technology more broadly in the Elk Valley. It was constructed with approximately 16.5 Mm3 of run of mine rock and 1.5 Mm3 of fine-grained materials using bottom-up construction techniques. The constructed facility includes five compacted horizontal layers (SOZ Layers) designed to limit oxygen movement through the spoil and placed between 20 m lifts of run-of-mine rock. The SOZ layers were constructed with finer texture material that was intended to have sufficiently low air permeability to decrease oxygen resupply and promote development of suboxic conditions within the CN SOZ spoil. In situ instrumentation, including pore-gas sampling ports, oxygen sensors and temperature sensors were installed to monitor leading indicators of performance of the facility. Seepage collection basins were installed to collect seepage from within the spoil and the results will be used to assess the evolution of water quality and quantity within the spoil over time.