The minewater at Cuthill is net alkaline and, therefore ideally suited to treatment by a passive system; in this instance by settlement lagoons and reedbeds. The raw minewater is pumped from a remote point to the treatment scheme. The raw minewater is collected in a chamber 3m in diameter and 4.5m deep. From here the minewater is pumped 240m via a rising main eventually discharging into a 65m long aeration cascade which lowers the water 10.5m in 150mm steps. The areated water then enters two settlement lagoons; the lagoons operate in parallel to enable one stream to be emptied for maintenance purposes. The ponds allow at least 8 hours retention time before the minewater is passed into the first of the three reedbeds. The settlement lagoons have a surface area of 347m2 and 334m2 respectively and both are 1.5m deep. Secondary treatment of the water occurs in three aerobic wetlands which operate in series. The total reedbed area at Cuthill equates to 3016m2. These beds provide the final polishing of the semi-treated water to enable it to be released into the Breich Water. |
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