Case study:Minsterley Brook Abandoned Metal Mines
Project overview
| Status | In progress |
|---|---|
| Project web site | |
| Themes | Environmental flows and water resources, Habitat and biodiversity, Monitoring, Water quality |
| Country | England |
| Main contact forename | Andrew |
| Main contact surname | Pearson |
| Main contact user ID | |
| Contact organisation | Environment Agency |
| Contact organisation web site | |
| Partner organisations | The Coal Authority (UK) |
| Parent multi-site project | |
| This is a parent project encompassing the following projects |
No |
Project summary
Minsterley Brook catchment includes a number of separate mines as part of the South Shropshire Metal Mining area, including Snailbeach, Tankerville, and Roman Gravels mines. The catchment is part of the Rea Brook which drains into the main River Severn at Shrewsbury. The mines were worked for mainly lead ores, but also zinc ore and latterly barites until closure in the 1940s, leaving spoil deposits and drainage adits which discharge to Minsterley Brook at various points. The mines are a significant source of heavy metal pollution in the catchment, and the discharges from them represent one of the longest continuous sources of pollution in the whole Severn River Basin.
Our routine monitoring found there were high levels of zinc in Minsterley Brook over most of its length, exceeding the Environmental Quality Standards (EQS) for the brook (75ug/l). As a result, the watercourse isn't achieving the 'Good status' for water quality as set out in our Severn River Basin Plan. The Boat Level adit discharge is the main source of the zinc (around 3000kg per annum) and other heavy metals, such as cadmium and lead, and discharges these pollutants into the Hogstow Brook. Immediately downstream of the Boat Level adit the zinc concentrations are up to 47x the EQS. At Minsterley, the zinc concentrations are 8x the EQS. Downstream of the mines, concentrations exceed the EQS for 15km, until the Rea Brook reaches Hanwood and dilution from other rivers lowers the concentration to below the EQS.
Ecological surveys of the brooks have found aquatic insects were suffering as a result of these heavy metals, which can settle in river sediments. There is also a lower than expected population of small fish species. There are four other, smaller discharges of metals into the catchment from Snailbeach Spoil Tip, Wood Adit, Roman Gravels and Tankerville spoil tips, which together contribute about a quarter of the metal load in wet conditions. These spoil heaps are listed on the Mining Waste Directive Inventory of sites causing serious environmental harm.
We're continuing to investigate and monitor the water quality in the Minsterley and Rea Brooks, and with funding from Defra, we've set up a partnership with the Coal Authority to look at options for potentially removing the metals from discharges from the Boat Level and Snailbeach Spoil Tip to improve the water quality. As part of a national initiative, Newcastle University are carrying out trials of treatment technologies which show potential to remove the metals from the discharges. This would deal with the problem at the source and help the Minsterley and Rea Brooks to meet the EQS and return to 'good' ecological and chemical status.