| The Herberton Tailings Storage Facility (TSF) is a legacy site situated in the township of Herberton on the Atherton Tablelands. The TSF was constructed in 1965 to receive tailings from the nearby mill operated by Great Northern Mining Corporation (GNMC). Prior to 1965, tailings from the mill were deposited directly into the Wild River.
The TSF site was surrendered to the Queensland Government in 1989 and is now managed under the Abandoned Mines Lands Program (AMLP) by the Technical Services (TS) team of DNRME. From 1997 to 2000, rehabilitation activities consisted of earthworks to form diversion banks and drains and preparing the site for capping. The capping cover consisted of a capillary break layer, to prevent leaching of heavy metals to the surface, and an impermeable clay layer, to direct water to drop out structures and subsequent receiving drains, whilst preventing flow through the tailings. A basic passive treatment system was installed at the toe of the TSF to treat any seepage, though records indicate it was not adequate. Seepage water of poor quality now emanates from the toe of the TSF.TS require the services of a geotechnical/ environmental drilling rig to enable the safe and efficient sampling of tailings material within the TSF. The TSF consists of 3 benches referred to as the upper, middle and lower bench. Each bench is accessible via 4wd either from River Terrace, Lyall or Amy Street.
The investigation will consist of drilling approximately 20 boreholes in a 50m grid pattern (Figure 2), with 3 to 4 samples taken per borehole. Boreholes are to be drilled via an auger with a helical screw to a maximum depth of 12m on the upper bench, with shallower depths of approximately 6m to <3m expected on the middle and lower benches. Material encountered is expected to be no bigger than coarse gravels and has previously been drilled through using a stem auger drill rig with a 204 mm (8”) diameter drill bit
The boreholes are to be backfilled as best as possible, with tailings material placed back first, covered by the original cover material. It may be necessary to clearly stockpile the cover material away from tailings material in order to achieve best results.
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