Bullhouse Minewater Treatment Scheme

Site History - Deep mining has taken place in this part of Yorkshire for many years and in 1870-1880 a series of drainage adits were constructed to de-water the workings. Deep mining ceased in 1918 but drift mining continued well into the 1960’s. The discharge has been issuing for many years and in 1996 a consortium involving the Coal Authority, the Environment Agency, Barnsley Metropolitan Borough Council and Hepworth Building products looked at the problem and came up with a proposal utilising the void of a fireclay quarry which was coming to the end of its life at the time.

Water Chemistry - Minewater treatment at Bullhouse was intended to reduce the impact on the River Don, and also the Little Don. A length of up to 6km was affected.

The water flow at the site is via a pumping system with pumping values ranging from 20 l/sec to 80 l/sec. Iron concentration is in the range of 30 mg/l to 50 mg/l and the pH of the water is 4.4 and 5.8.

Site Design - The minewater at Bulhouse is net Acid, therefore it was thought that Aeration and Settlement treatment would lead to the lowering of the pH and Iron content. However, it was decided that the large volume available for settlement in the Bullhouse Quarry would provide a sufficiently long retention time for full oxidisation and settlement of ferrous iron to occur even under acid conditions. Alkali chemicals may be needed on a flexible basis, to alleviate the effects of peak flows from the adit.

The lagoon in the quarry has a surface area of 7000m², a depth of 8m and a capacity in the region of 50,000m³. This gives a retention time of 16 days for the water to be held in the lagoon. The prevailing wind is across the lagoon and not along. Therefore this reduces the wave action and gives adequate settling of the precipitated ochre.

The minewater then passes into a smaller polishing pond, this has an area of 582m², a depth of 1.5 2m, and the polishing pool has a retention time of 0.3 days. From the polishing pond the water is pumped back to the River Don.

The costs for the Bulhouse minewater treatment scheme were approximately £1.2million. Most of this was for pumping equipment and pipes. The lagoon itself cost about £120,000.