September 8, 1995. Copyright, 1995, Graphic News. All rights reserved

NB EDITORS Ð GRAPHIC AND STORY EMBARGOED TILL MIDNIGHT GMT, MONDAY, SEPTEMBER 11

OLD KING COALÕS LAST REVENGE
By Nicholas Booth, Science Editor

LONDON, September 12, Graphic News- A deletrious legacy from one of BritainÕs longest-established industries will continue for many years after its demise, a scientist based at the University of Newcastle reports today at the British Association. And unless care is taken, suggests Dr. Paul Younger, a lecturer in Water Resources, pollution from old mines will continue, especially if pumping stations are abandoned. 

ÔThe chemistry of abandoned deep mines is capricious,Õ Dr Younger says. ÔSome abandoned mines emit waters which are extremely polluting. Others produce waters which are suitable for use in public supply. No two mines are alike and we donÕt fully understand the processes.Õ

Dr. Younger highlights a number of cases from around the country. Communities in the Yorkshire Dales, for example, receive their water supply from water which discharges through old lead mines. On the other hand, iron-rich waters from the Ynysarwed Field in South Wales seeped out to the surface where no-one expected them and have severely polluted the Neath canal. And worst of all is drainage from the abandoned Randolph Colliery in Fife, where a froth-like run-off has been found.

Water has always been a source of nuisance to miners. Working at coal faces knee deep in water was a common occurence and sudden inrushes of water claimed untold lives. The water comes from rainfall which permeates through the rock strata and perpetual pumping was needed to keep mines from flooding. It is estimated that the amount of water pumped from deep mines in the North East is more than double the amount of coal which was extracted. ÔAs long as the pumping continues to match the rate at which water is recharging, then minewater levels will not rise,Õ Dr. Younger explains.

The worst offenders are not the deepest mines but the shallower ones whose seams are extracted above the water table. Mines below the water table have any potential pollutants flushed away by the seepage of rainfall. But rising levels of water become saturated with minerals which have been left behind in strata that have been mined and would otherwise disperse. The result is that a flooded mine will often produce highly acidic, polluted water from even the smallest traces of metals like pyrite. 

By far the worst metallic pollutants are oxides of iron, which degrade river water quality and coat stream beds and river banks with their characteristic orange colouration. Such waters serve to destroy aquatic life if they seep into nearby rivers, as happened in 1993, when virtually all life was destroyed over a 12 kilometre stretch of the Neath Canal.

The prospect for the North East is mixed, Dr. Younger reports. In 1986, British Coal withdrew its pumping stations on the Northumberland coalfield and minewater levels are rising. ÔOn past evidence the prospects for the Rivers Blyth and Wansbeck do not seem encouraging,Õ he says. But the closure of the Durham mines in 1992 saw public pressure to maintain pumping stations at a cost of £1 million per year. Maintaining these stations is a sensible precaution, says Dr. Younger, because it would be far more expensive in the long run to treat polluted water which might discharge into rivers like the Wear.  ÔPlanning ahead is difficult and weÕve got to be careful because we canÕt predict what will happen.Õ 

Sources: Department of Civil Engineering, University of Newcastle