Case study:River Nent: Abandoned Metal Mines: Difference between revisions

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{{Case study status
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|Partner organisations=The Coal Authority (UK),
|Partner organisations=The Coal Authority (UK),
|Multi-site=No
|Multi-site=No
|Project summary=There have been lead mines in the Nent valley since Roman times, and over 90 mine entries have been recorded throughout the area. As technology advanced in the 1700s and 1800s and longer tunnels and drainage levels could be constructed, the centres of activity became concentrated around Nenthead and Nentsberry. The Nent Force drainage Level was constructed in the 1800s and runs over 7 miles from the Nenthead mines to discharge in Alston. By the 1920s mining had ceased, but during the second world war spoil heaps were reworked for lead and zinc, leaving behind large tailings dams downstream of Nenthead village. In 1998 these were capped and stabilised by Cumbria County Council.
|Project summary=The EU Water Framework Directive (WFD) sets out a legislative framework for the analysis, planning and management of water bodies. In England it is delivered through River Basin Management Plans (RBMP), which describe waterbody conditions and objectives for their improvement.
The River Nent is ranked as the most impacted catchment in the Northumbrian River Basin District and the 2nd worst in England with respect to mine water related pollution. The River Nent waterbody is assessed in the current RBMP (2015) as failing to achieve the required WFD objective of ‘Good Potential’. For the River Nent to achieve the required objective, the levels of zinc, cadmium and lead need to be reduced, together with other measures to improve its quality.


The history and extent of mining here has left large areas of contaminated spoil with little vegetation cover - as a result, spoil is being eroded by the high rainfall and washed into the River Nent. Two sites in the catchment are listed on the MINING WASTE DIRECTIVE INVENTORY since they cause serious pollution. Many of the spoil heaps are protected as Scheduled Ancient Monuments for industrial heritage and/or Sites of Special Scientific Interest (SSSI), as the high metal levels allow unusual calaminarian grasslands to flourish. There are four major mine water discharges which pollute the river with cadmium, zinc and lead, and several smaller discharges in the valley.
There have been lead mines in the Nent valley since Roman times, and over 90 mine entries have been recorded throughout the area. As technology advanced in the 1700s and 1800s and longer tunnels and drainage levels could be constructed, the centres of activity became concentrated around Nenthead and Nentsberry. The Nent Force drainage Level was constructed in the 1800s and runs over 7 miles from the Nenthead mines and discharges to the River Nent at Alston. By the 1920s mining had ceased, but during the second world war spoil heaps were reworked for lead and zinc, leaving behind large tailings dams downstream of Nenthead village. In 1998 these dams were capped and stabilised by Cumbria County Council.


The many inputs of metals into the River Nent cause average concentrations of 1,500 ug/l zinc, 3 ug/l cadmium (exceeding the Environmental Quality Standard (EQS) by over 30 times) and 15 ug/l lead (twice the EQS). Due to this very high pollution, very little invertebrate life can live in a 10km+ stretch of the river. The River Nent joins the River South Tyne at Alston, causing it to also fail EQS for zinc and cadmium for 50 km downstream.
The history and extent of mining here has left large areas of contaminated spoil with little vegetation cover; as a result, spoil is being eroded by high rainfall and washed into the River Nent. Two sites in the catchment are listed on the MINING WASTE DIRECTIVE INVENTORY since they cause serious pollution. Many of the spoil heaps are protected as Scheduled Ancient Monuments for industrial heritage and/or Sites of Special Scientific Interest (SSSI), as the high metal levels allow rare calaminarian grasslands to flourish.  


Investigations by Newcastle University indicate that the River Nent contributes over 50% of the total load of metals (lead and zinc) reaching the Tyne estuary every year. Reducing the inputs from mines in the River Nent would improve the water quality of the River South Tyne and help reduce the risks to sediment quality in the Tyne estuary. The Environment Agency have teamed up with other partners to look at ways to reduce the polluting effects of the mines on the River Nent, with funding from Defra. We're working with the Coal Authority and Newcastle University to find ways of passively removing zinc from mine water discharges at Nenthead. We're also working with the Tyne Rivers Trust and North Pennines AONB Partnership to stabilise the spoil using metal tolerant plants. This will help reduce the amounts of metal-rich sediments being washed into the river. The Nenthead mines site is a Scheduled Ancient Monument and a SSSI, and we are working with Natural England to monitor spoil erosion and minimise the deterioration of the heritage.
The mining industry has left a huge underground network of mine workings. The workings drain different parts of the Nent catchment and also act as a preferential pathway for groundwater to reach the surface. These drainage pathways allow the water to come into contact with the mineral veins that were mined and with mine waste stored within the mine workings. This causes the water to become rich in metals like  zinc, cadmium and lead. The water from the mine workings discharges at several locations throughout the Nent valley. There are four known main discharges that contribute significant amounts of metals to the River Nent: two at Nenthead, (Caplecleugh and Rampgill adits), one at Nentsberry (Haggs adit) and the Nent Force Level at Alston.  
The many inputs of metals into the River Nent cause average concentrations at Alston to exceed Environmental Quality Standards (EQS) by up to 57 times (57 times for zinc, 28 times for cadmium and 3 times for lead according to the EA catchment characterisation report). Due to this high level of pollution, very little invertebrate life can live in a 10km+ stretch of the river. The River Nent joins the River South Tyne at Alston, bringing the pollution with it and causing the River South Tyne  to also fail EQS for zinc and cadmium for 60km downstream.


There are so many point and diffuse sources of zinc, cadmium and lead in the area that we're unlikely to be able to achieve EQS in the River Nent itself. However, we hope to be able significantly improve water quality and therefore achieve good status in around 50 km of the River South Tyne.
Investigations by Newcastle University indicate that the River Nent contributes over 50% of the total metal load (lead and zinc) reaching the South Tyne every year. Reducing the impacts from mines in the Nent valley would improve the water quality of the River Nent and all of the downstream waterbodies, and would be a significant step in achieving EQS in the South Tyne.


Impact of mine water discharges in the River Nent (four discharges):
The Environment Agency has teamed up with other partners to look at ways to reduce the polluting effects of the mines on the River Nent, with funding from Defra. We're working with the Coal Authority and the North Pennines Area of Outstanding Natural Beauty partnership (AONB) to find ways of removing metals from mine water discharges at three of the four main discharges. We're also working with the Tyne Rivers Trust on ways to reduce the amount of metal-rich sediments that get washed into the river – for example willow planting. Without any action, these mines will continue to pollute the Rivers Nent and South Tyne for centuries to come.
• Length of watercourse affected=50km (five water bodies)
• Average metal concentration: Zinc = 1.5-6.8 mg/l; Cadmium = 3-12 ug/l
• Average flow = 2-14 l/sec
• Load of zinc discharged per annum = 25 Tonnes
• Water body ecological status = Moderate


Benefits of remediation
There are so many point and diffuse sources of zinc, cadmium and lead in the area that we're unlikely to be able to achieve EQS in the River Nent itself. However, we hope to be able to significantly improve water quality and therefore achieve good status in around 60 km of the River South Tyne. Other benefits of tackling these sources of pollution include improving habitats for aquatic life, increasing biodiversity and protecting Scheduled Ancient Monuments. 
• The River Tyne will be protected from a major pollution source
 
• A scheduled ancient monument is prevented from being damaged by water erosion
Treatment schemes will be required to clean up all these discharges and the spoil heaps, and we’re investigating the best ways of doing this. We expect the first scheme will be to treat the Haggs discharge. The treatment scheme is being designed to remove at least 90% of zinc and cadmium from the mine water – making  a significant improvement to water quality in the Nent at Alston and also the South Tyne.
• We're developing partnerships with important stakeholders and using our position as an influential advisor to secure shared environmental outcomes
 
• Contribute towards achieving Good Ecological and Chemical status
 
• 25 Tonnes of zinc would be prevented from entering R Tyne every year
What technology is available?
|Monitoring surveys and results=Significant water quality monitoring of the River Nent and the point sources discharges from the abandoned metal mines has been carried out by the Environment Agency in recent years.   
 
One treatment technology that is available is a Vertical Flow Pond (VFP) and a wetland, similar to the scheme at Force Crag mine in Cumbria, the first treatment scheme of its type in the UK. The shape and size of the Nent schemes will be different, and is likely to look like a series of large ponds, along with a wetland containing reeds and other plants.
 
The VFPs work by using a combination of compost, limestone and woodchip to encourage microbial activity to bind the dissolved metals as sulphides, trapping them in the compost mixture. The water is then passed through a wetland to re-oxygenate the water before finally being discharged to the River Nent.
 
 
 
 
|Monitoring surveys and results=Significant water quality monitoring of the River Nent and the point source discharges from the abandoned metal mines has been carried out by the Environment Agency in recent years.
The water quality results from 3 of the main discharges are summarised below. As the concentrations of metals and rate of flow is variable in discharges like these, the figures below are presented as minimum to maximum ranges taken from the EA catchment characterisation report.
 
Caplecleugh
• Zinc:2700 -  8810 kg/yr
• Lead: 0 – 10 kg/yr
• Cadmium: 0 - 10 kg/yr
 
Rampgill
• Zinc: 170 - 400 kg/yr
• Lead: 0 – 2kg/yr
• Cadmium: 0.24 - 0.76 kg/yr
 
Haggs
• Zinc: 2000 – 5100 kg/yr
• Lead: 0 – 1 kg/yr
• Cadmium: 2 – 3.3 kg/yr
 
River Nent at Alston
• Zinc: 2300 - 35000 kg/yr
• Lead: 20 – 600 kg/yr
• Cadmium: 10 - 90 kg /yr
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|Invasive species present=No
|Invasive species present=No
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{{Motivations}}
|Project started=2015/01/01
{{Measures}}
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{{Motivations
|Specific mitigation=Mine water related pollution, Aggregate/mineral extraction, Mining runoff
|Physico-chemical quality elements=Nutrient concentrations, Zinc, Cadmium, Lead
}}
{{Measures
|Floodplain / River corridor=Planting, Habitat enhancement, Treatment/clean up schemes, Riparian planting,
|Management interventions=Reduce diffuse water pollution and over-grazing, Reduced pollution, reduce diffuse water poluution,
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{{Additional links and references
|Link=http://apps.environment-agency.gov.uk/wiyby/139297.aspx
|Description=Details of sites listed in the Mining Waste Directive Inventory
}}
{{Additional links and references
|Link=https://historicengland.org.uk/listing/the-list/map-search?clearresults=True
|Description=Find out more about Scheduled Ancient Monuments
}}
{{Additional links and references
|Link=http://magic.defra.gov.uk/MagicMap.aspx?startTopic=Designations&activelayer=sssiIndex&query=HYPERLINK%3D%271005625%27
|Description=Find out more about Designated sites
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{{Additional links and references
|Link=https://www2.groundstability.com/force-crag-mine-water-treatment-scheme/
|Description=Force Crag Mine Water Treatment scheme
}}
{{Additional links and references
|Link=https://www.gov.uk/government/organisations/the-coal-authority
|Description=The Coal Authority
}}
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Latest revision as of 14:01, 1 June 2017

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Location: 54° 47' 51.71" N, 2° 23' 11.86" W
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Project overview

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Status In progress
Project web site
Themes Environmental flows and water resources, Habitat and biodiversity, Monitoring, Water quality
Country England
Main contact forename Hugh
Main contact surname Potter
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
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Project summary

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The EU Water Framework Directive (WFD) sets out a legislative framework for the analysis, planning and management of water bodies. In England it is delivered through River Basin Management Plans (RBMP), which describe waterbody conditions and objectives for their improvement.

The River Nent is ranked as the most impacted catchment in the Northumbrian River Basin District and the 2nd worst in England with respect to mine water related pollution. The River Nent waterbody is assessed in the current RBMP (2015) as failing to achieve the required WFD objective of ‘Good Potential’. For the River Nent to achieve the required objective, the levels of zinc, cadmium and lead need to be reduced, together with other measures to improve its quality.

There have been lead mines in the Nent valley since Roman times, and over 90 mine entries have been recorded throughout the area. As technology advanced in the 1700s and 1800s and longer tunnels and drainage levels could be constructed, the centres of activity became concentrated around Nenthead and Nentsberry. The Nent Force drainage Level was constructed in the 1800s and runs over 7 miles from the Nenthead mines and discharges to the River Nent at Alston. By the 1920s mining had ceased, but during the second world war spoil heaps were reworked for lead and zinc, leaving behind large tailings dams downstream of Nenthead village. In 1998 these dams were capped and stabilised by Cumbria County Council.

The history and extent of mining here has left large areas of contaminated spoil with little vegetation cover; as a result, spoil is being eroded by high rainfall and washed into the River Nent. Two sites in the catchment are listed on the MINING WASTE DIRECTIVE INVENTORY since they cause serious pollution. Many of the spoil heaps are protected as Scheduled Ancient Monuments for industrial heritage and/or Sites of Special Scientific Interest (SSSI), as the high metal levels allow rare calaminarian grasslands to flourish.

The mining industry has left a huge underground network of mine workings. The workings drain different parts of the Nent catchment and also act as a preferential pathway for groundwater to reach the surface. These drainage pathways allow the water to come into contact with the mineral veins that were mined and with mine waste stored within the mine workings. This causes the water to become rich in metals like zinc, cadmium and lead. The water from the mine workings discharges at several locations throughout the Nent valley. There are four known main discharges that contribute significant amounts of metals to the River Nent: two at Nenthead, (Caplecleugh and Rampgill adits), one at Nentsberry (Haggs adit) and the Nent Force Level at Alston.

The many inputs of metals into the River Nent cause average concentrations at Alston to exceed Environmental Quality Standards (EQS) by up to 57 times (57 times for zinc, 28 times for cadmium and 3 times for lead according to the EA catchment characterisation report). Due to this high level of pollution, very little invertebrate life can live in a 10km+ stretch of the river. The River Nent joins the River South Tyne at Alston, bringing the pollution with it and causing the River South Tyne to also fail EQS for zinc and cadmium for 60km downstream.

Investigations by Newcastle University indicate that the River Nent contributes over 50% of the total metal load (lead and zinc) reaching the South Tyne every year. Reducing the impacts from mines in the Nent valley would improve the water quality of the River Nent and all of the downstream waterbodies, and would be a significant step in achieving EQS in the South Tyne.

The Environment Agency has teamed up with other partners to look at ways to reduce the polluting effects of the mines on the River Nent, with funding from Defra. We're working with the Coal Authority and the North Pennines Area of Outstanding Natural Beauty partnership (AONB) to find ways of removing metals from mine water discharges at three of the four main discharges. We're also working with the Tyne Rivers Trust on ways to reduce the amount of metal-rich sediments that get washed into the river – for example willow planting. Without any action, these mines will continue to pollute the Rivers Nent and South Tyne for centuries to come.

There are so many point and diffuse sources of zinc, cadmium and lead in the area that we're unlikely to be able to achieve EQS in the River Nent itself. However, we hope to be able to significantly improve water quality and therefore achieve good status in around 60 km of the River South Tyne. Other benefits of tackling these sources of pollution include improving habitats for aquatic life, increasing biodiversity and protecting Scheduled Ancient Monuments.

Treatment schemes will be required to clean up all these discharges and the spoil heaps, and we’re investigating the best ways of doing this. We expect the first scheme will be to treat the Haggs discharge. The treatment scheme is being designed to remove at least 90% of zinc and cadmium from the mine water – making a significant improvement to water quality in the Nent at Alston and also the South Tyne.


What technology is available?

One treatment technology that is available is a Vertical Flow Pond (VFP) and a wetland, similar to the scheme at Force Crag mine in Cumbria, the first treatment scheme of its type in the UK. The shape and size of the Nent schemes will be different, and is likely to look like a series of large ponds, along with a wetland containing reeds and other plants.

The VFPs work by using a combination of compost, limestone and woodchip to encourage microbial activity to bind the dissolved metals as sulphides, trapping them in the compost mixture. The water is then passed through a wetland to re-oxygenate the water before finally being discharged to the River Nent.

Monitoring surveys and results

Edit project overview to modify the Monitoring survey and results.


Significant water quality monitoring of the River Nent and the point source discharges from the abandoned metal mines has been carried out by the Environment Agency in recent years. The water quality results from 3 of the main discharges are summarised below. As the concentrations of metals and rate of flow is variable in discharges like these, the figures below are presented as minimum to maximum ranges taken from the EA catchment characterisation report.

Caplecleugh • Zinc:2700 - 8810 kg/yr • Lead: 0 – 10 kg/yr • Cadmium: 0 - 10 kg/yr

Rampgill • Zinc: 170 - 400 kg/yr • Lead: 0 – 2kg/yr • Cadmium: 0.24 - 0.76 kg/yr

Haggs • Zinc: 2000 – 5100 kg/yr • Lead: 0 – 1 kg/yr • Cadmium: 2 – 3.3 kg/yr

River Nent at Alston • Zinc: 2300 - 35000 kg/yr • Lead: 20 – 600 kg/yr • Cadmium: 10 - 90 kg /yr

Lessons learnt

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Image gallery


Vertical Flow Pond diagram


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Catchment and subcatchment

Catchment

River basin district Northumbria
River basin Tyne

Subcatchment

River name Nent from Source to South Tyne
Area category 10 - 100 km²
Area (km2)
Maximum altitude category 500 - 1000 m
Maximum altitude (m) 672672 m <br />0.672 km <br />67,200 cm <br />
Dominant geology Siliceous
Ecoregion Great Britain
Dominant land cover Acid Grassland
Waterbody ID GB103023075420



Site

Name
WFD water body codes GB103023075420
WFD (national) typology
WFD water body name Nent from Source to South Tyne
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 2015/01/01
Works started
Works completed
Project completed
Total cost category
Total cost (k€)
Benefit to cost ratio
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 Mine water related pollution, Aggregate/mineral extraction, Mining runoff
Hydromorphology
Biology
Physico-chemical Nutrient concentrations, Zinc, Cadmium, Lead
Other reasons for the project


Measures

Structural measures
Bank/bed modifications
Floodplain / River corridor Planting, Habitat enhancement, Treatment/clean up schemes, Riparian planting
Planform / Channel pattern
Other
Non-structural measures
Management interventions Reduce diffuse water pollution and over-grazing, Reduced pollution, reduce diffuse water poluution
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

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

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

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


Monitoring documents



Additional documents and videos


Additional links and references

Link Description
http://http://apps.environment-agency.gov.uk/wiyby/139297.aspx Details of sites listed in the Mining Waste Directive Inventory
http://https://historicengland.org.uk/listing/the-list/map-search?clearresults=True Find out more about Scheduled Ancient Monuments
http://http://magic.defra.gov.uk/MagicMap.aspx?startTopic=Designations&activelayer=sssiIndex&query=HYPERLINK%3D%271005625%27 Find out more about Designated sites
http://https://www2.groundstability.com/force-crag-mine-water-treatment-scheme/ Force Crag Mine Water Treatment scheme
http://https://www.gov.uk/government/organisations/the-coal-authority The Coal Authority

Supplementary Information

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