Case study:Force Crag Mine Remediation

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Location: 54° 35' 2", -3° 14' 17"
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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, 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.

Monitoring surveys and results

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Lessons learnt

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Image gallery


April 2014. Completed Force Crag mine water treatment scheme. Photo by John Malley.
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Catchment and 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) 840
840 m
0.84 km
84,000 cm
Dominant geology Siliceous
Ecoregion Great Britain
Dominant land cover Acid Grassland
Waterbody ID GB112075070440



Site

Name
WFD water body codes GB112075070440
WFD (national) typology
WFD water body name Newlands Beck
Pre-project morphology
Reference morphology
Desired post project morphology
Heavily modified water body No
National/international site designation
Local/regional site designations
Protected species present No
Invasive species present No
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

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

Mitigation of a pressure Historic mining activities
Hydromorphology
Biology
Physico-chemical Nutrient concentrations, Oxygen balance
Other reasons for the project


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

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Biological quality elements

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Physico-chemical quality elements

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Any other monitoring, e.g. social, economic

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative


Monitoring documents



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Supplementary Information

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