Case study:Force Crag Mine Remediation

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Location: 54° 35' 1.78" N, 3° 14' 17.44" W

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Project overview

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Status	In progress
Project web site
Themes	Habitat and biodiversity, Water quality
Country	England
Main contact forename	Hugh
Main contact surname	Potter
Main contact user ID	User:HPotter
Contact organisation	Environment Agency
Contact organisation web site
Partner organisations	The Coal Authority (UK), Defra (Dept for Environment, Food and Rural Affairs), National Trust, Newcastle University
Parent multi-site project
This is a parent project encompassing the following projects	No

April 2014. Completed Force Crag mine water treatment scheme. Photo by John Malley.

Project summary

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Force Crag mine, worked for zinc, lead and barytes until 1991, was famously the last working mine in the Lake District. Mine water discharges and diffuse pollution from waste heaps mean it's a major source of cadmium, zinc and lead, depositing around 3 tonnes each year into the watercourse. The metals pollute the Coledale Beck and the Newlands Beck as far as Bassenthwaite Lake, and prevent these water bodies achieving good Chemical and Ecological status for the Water Framework Directive.

The site is now owned by the National Trust and run as a visitor attraction. It's within the Lake District High Fells SAC and two SSSI’s; Force Crag mine itself and Buttermere High Fells. It is also a Scheduled Monument.

We've been working in partnership with the Coal Authority, the National Trust and Newcastle University to develop a remediation scheme for this site with funding from Defra. The ‘vertical flow pond’ designed by Newcastle University is the first of its kind in the UK and uses compost, limestone and woodchips to remove metals from the water without the need for added energy or chemicals. This passive system works by passing the mine water down through the compost mixture where microbial activity binds the metals as sulphides, before discharging through a small wetland and into the Coledale Beck.

In September 2013, the Coal Authority began building the treatment scheme within the existing bunding of the former tailings lagoon. The National Trust and English Heritage supported the scheme as the next stage in the life cycle of this historic industrial site. On 31 March 2014, the valves were opened and mine water started filling up the ponds...

The system has now been operating for a year, and has removed over half a tonne of zinc. Although we're only treating some of the mine water flow (6 l/s), it's already making a significant difference to the water quality in the Coledale Beck since the scheme is removing >95% of the zinc, and >90% of the cadmium and lead. This is not yet enough for the river to achieve good status but we hope Bassenthwaite Lake will no longer fail the EQS for metals. Over the next couple of years we will see if the treatment system can cope with more of the flow without harming performance, and investigate how to deal with diffuse sources of metals in the catchment.

The benefits of cleaning up the Force Crag mine water are estimated to be up to £4.9m over 25 years, at a cost of~£1.5m.

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April 2014. Completed Force Crag mine water treatment scheme. Photo by John Malley.

Catchment and subcatchment Select a catchment/subcatchment Edit the catchment and subcatchment details (affects all case studies in this subcatchment) Catchment River basin district North West River basin Derwent (NW) Subcatchment River name Newlands Beck Area category 10 - 100 km² Area (km2) Maximum altitude category 500 - 1000 m Maximum altitude (m) 840840 m <br />0.84 km <br />84,000 cm <br /> Dominant geology Siliceous Ecoregion Great Britain Dominant land cover Acid Grassland Waterbody ID GB112075070440 Site Edit site Name WFD water body codes WFD (national) typology WFD water body name Pre-project morphology Reference morphology Desired post project morphology Heavily modified water body National/international site designation Local/regional site designations Protected species present Invasive species present Species of interest Dominant hydrology Dominant substrate River corridor land use Average bankfull channel width category Average bankfull channel width (m) Average bankfull channel depth category Average bankfull channel depth (m) Mean discharge category Mean annual discharge (m3/s) Average channel gradient category Average channel gradient Average unit stream power (W/m2) Project background Edit project background Reach length directly affected (m) Project started Works started 2013/09/02 Works completed Project completed Total cost category Total cost (k€) Benefit to cost ratio Benefits of cleaning up the Force Crag mine water are estimated to be £1.6m - £4.9m over 25 years, at a cost of ~£1.5m"BenefitsofcleaninguptheForceCragminewaterareestimatedtobe£" can not be assigned to a declared number type with value 1.6. Funding sources Cost for project phases Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname Investigation and design Stakeholder engagement and communication Works and works supervision Post-project management and maintenance Monitoring Reasons for river restoration Edit reasons for restoration Mitigation of a pressure Historic mining activities Hydromorphology Biology Physico-chemical Nutrient concentrations, Oxygen balance Other reasons for the project Measures Edit Measures Structural measures Bank/bed modifications Floodplain / River corridor Vertical flow pond which uses compost, limestone and woodchips to remove metals from the water without the need for added energy or chemicals Planform / Channel pattern Other Non-structural measures Management interventions Social measures (incl. engagement) Other Monitoring Hydromorphological quality elements Edit Hydromorphological quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Biological quality elements Edit biological quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Physico-chemical quality elements Edit Physico-chemical quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Any other monitoring, e.g. social, economic Edit Other responses Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Monitoring documents Upload monitoring documents Additional documents and videos Upload additional documents Additional links and references Edit links and references Link Description Supplementary Information Edit Supplementary Information