This study aimed to identify the water quality benefits of remediating two coal mine discharges, one in Scotland and one in Northern England. For each site, the assessment followed the updated coal methodology (RPA, 2015). The first stage involved the development of assumptions for the assessment, setting out key points such as the length of waterbody affected, the likely extent of the improvement in water quality, and whether this improvement would be sufficient to result in a status change under the Water Framework Directive (WFD).
The potential benefits of mine water treatment were assessed across a range of impact categories including, but not limited to, abstraction, informal recreation, angling and biodiversity and non-use. For the non-market benefits, the anticipated benefits were monetised through identifying the relevant population and applying benefits transfer values.
Final benefits were estimated in present value (PV) terms to enable comparison with cost estimates developed by the Coal Authority. Sensitivity analyses were carried out to test how changing the assumptions altered the benefits estimated. For the scheme in England, the National Water Environment Benefits Survey (NWEBS) values were used as a further sensitivity test.