Hydrogeochemistry of Durham Coalfield Minewater Pumped To the River Wear, N.E. England

• Published in: Environmental geochemistry and health Vol. 21; no. 4; pp. 339 - 345
• Main Authors: Green, R, Lord, Ra, Giusti, L
• Format: Journal Article
• Language: English
• Published: Kew Springer Nature B.V 01.12.1999
• Subjects: British Isles, England, Wear R; Freshwater; tributaries; British Isles, England, Durham, Wear R
• ISSN: 0269-4042; 1573-2983
• DOI: 10.1023/A:1006740502553

During recent mining of the Durham Coalfield, an extensive inland de-watering programme was needed to prevent down-dip flow towards the deep coastal collieries (Easington, Murton, Dawdon, Seaham, Vane Tempest, Wearmouth and Westoe). In the late 1980s, for example, 67 Mld super(-1) was pumped at the coast and 109 Mld super(-1) from shafts at abandoned inland collieries (Harrison et al., 1989). Inland pumping has continued, despite final closure of all deep mines, to prevent acid groundwater rebound and the surface discharges which are expected to follow (Younger, 1993). At present up to 71 Mld super(-1) of minewater is pumped from 8 sites between Bishop Auckland and Chester-le-Street directly into the River Wear or its tributaries. The mean average flow of the River Wear above Durham is 970 Mld super(-1) and minewater can provide up to 50% of flow passing the Lumley drinking water abstraction point in dry spells (Younger, 1993). A further northern pumping station Kibblesworth discharges 26 Mld super(-1) to a tributary of the Tyne in the Team Valley. Pumping costs the Coal Authority c pound sterling 1 million per annum (Younger, 1994) but if discontinued it is anticipated that uncontrolled seeps of low pH minewaters rich in metals will cause considerable environmental damage and reduce water quality in the River Wear (Younger, 1994). Furthermore, the future acidification of minewaters might remobilise those metals present in ochreous deposits and stream sediments at the discharge sites (Lord et al., 1999). This article describes sampling of the minewater discharges during overnight pumping, in order to fully determine their current hydrogeochemistry and to investigate seasonal variations therein.