Developing environmental regulator capability in source apportionment and remediation of mine pollution

In the 1850s, the UK was the world's leading producer of valuable metals such as lead, zinc and copper. Economic downturn and the discovery of larger metal deposits abroad forced the closure of most metal mines by the 1920s. However, solid waste and polluted drainage from these abandoned mines remains a major cause of water quality and ecosystem degradation today, almost one hundred years after the decline of this industry. The problem is particularly acute in Wales where over 1300 known abandoned mines cause up to 19% of rivers to fail environmental standards.

Three major innovations are required to tackle this problem. First, we need to develop methods to systematically screen mining-impacted river catchments to accurately identify and quantify sources of pollution in order to prioritise sites for remediation. Second, we need to develop modelling tools that allow the potential effectiveness of different remedial approaches (such as mine water treatment) to be evaluated in terms of improvements to water quality. Third, we need to develop novel approaches to treat, isolate or remove identified sources of mine pollution. This project addresses the first two of these innovations through case studies in the Nant Cwmnewyddion and Afon Crafnant catchments in central and north Wales, respectively.

Innovation (1). Source identification of mine pollution requires synchronous measures of streamflow and metal concentrations in order to calculate stream metal loads. Multiple metal loading estimates across a river catchment provides an overview (or synoptic) assessment of mine pollution sources. The more measurements of stream metal loads across a catchment, the more detail on mine pollution sources can be extracted for remediation planning. However, the current approach used by Natural Resources Wales (and other environmental regulators) for identifying sources of mine pollution does not provide the necessary spatial detail to capture all possible sources of mine pollution across a catchment. To overcome this issue, this project will demonstrate an innovative approach for identifying sources of pollution at a previously unachievable spatial resolution. Specifically, the project will use a hydrologic tracer injected into the river to calculate stream metal loads. The major advantage of using a tracer is that it provides order-of-magnitude improvements in the accuracy and number of samples that can be collected and therefore delivers the level of spatial detail required to pinpoint sources of pollution.

Innovation (2) There is currently no method in the UK for evaluating the potential effectiveness of different mine pollution remediation scenarios. This is partly due to the lack of appropriate data required to run remediation models. This project will demonstrate how data derived from hydrologic tracer studies can be used to develop a modelling tool capable of simulating the effect of hypothetical remediation scenarios on water quality. This will ensure that remediation schemes are designed and targeted to yield the most environmental and economic benefit possible.

This project is a collaborative effort between Natural Resources Wales (NRW) and Liverpool John Moores University and builds on previous RCUK-funded research (NE/M017486/1; FENAC/2016/11/008; Diamond SP17227) broadly concerned with improving water quality in mining-impacted catchments. The key aim is to develop NRW expertise in the use of hydrologic tracers and remediation modelling so that they can prioritise those mine sites for remediation that will deliver the most environmental and economic benefit. It is estimated that cleaning up rivers polluted by mine wastes could benefit the Welsh economy by £30-£49M over 25 years through: increased recreational activity (e.g. fishing); tourism; enhanced water quality for public supply, agriculture, industry and power generation; job creation; and by providing national and international research opportunities.