Case study:Saltburn Gill ironstones mines

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Location: 54° 34' 19", -0° 57' 37"
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Project overview

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Status In progress
Project web site
Themes Economic aspects, Social benefits, 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 http://www.environment-agency.gov.uk/
Partner organisations Environment Agency, Defra, 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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Saltburn Gill is a short coastal river, flowing into the North Sea across Saltburn Beach - a designated bathing water beach and one of the most popular surfing beaches on the east coast. The river extends inland for about 8km in a steep sided valley, part of the Saltburn Gill Nature Reserve Site of Special Scientific Interest (SSSI).

This on-going project targets a section of the Saltburn Gill that was negatively impacted by Acid Mine Drainage (AMD) from abandoned mine workings, located upstream of the discharge point. Historically, East Cleveland was a major source of ore for the Teesside iron and steel industry, specially from the 1850’s until the early 1960’s. Afterwards, the decline of the mining activity resulted in an uncontrolled abandonment of the working mines in within the region.

In May 1999, an uncontrolled mine discharge increased the typical iron levels of the Saltburn Beck from around 0.1 milligrammes per litre (mg/l) to in excess of 1200mg/l. Over 330kg of iron ochre was deposited on the stream bed every day. In one year, this is the equivalent of over 100 tonnes of iron being discharged into the North Sea. The devastating effects on the ecology readily appeared, mainly due to the drastic depletion in the oxygen levels. A biological impact survey of the stream showed that the pollution reduced the water quality of the beck from good to bad status along 2km of the watercourse, from the discharge point to the sea.

The Saltburn Gill Action Group (SGAG) was set up in 2005 as a community action group. Assistance was given by The Environment Agency, Teesside University, the local Wildlife Trust, the Parish Council and others to try to find a solution to this problem. Then, several site investigations were carried out with insights to build up a treatment plant. A major partnership project between us, the Coal Authority and Saltburn Gill Action Group has been working to clean up the pollution since 2008.

During the summer of 2013, Defra provided funding for the Coal Authority to pump water from the mines and build the first stage of a treatment scheme. This first stage is a settlement lagoon where iron precipitates out of the mine water to form a sludge at the bottom. A temporary chemical dosing system helps to remove more iron while the second stage is being built. Clean water is put back into the Gill, and since January 2014, the stream is no longer orange.

In the summer of 2014, work started on the second stage of the passive treatment scheme – made up of 4 settlement ponds, a sludge drying bed and a reed bed wetland. The abstracted mine water first flows over an aeration cascade, which adds oxygen to the water and improves the rate the iron oxidises into a precipitate. It then flows by gravity into settlement ponds, where the metals can settle out to the bottom. This process takes 1 to 2 days, and leaves a sludge, iron ochre, which is disposed of at a later date.

After the mine water has passed through the settlement ponds it then flows by gravity into the reed bed wetland. The reeds act like a natural filter, removing the majority of the remaining metal pollution. Clean water is then returned to the Gill. Once the treatment scheme is finished, the chemical dosing system can be removed – reducing long-term costs. The construction phase should be completed in early 2015, and the reeds will be planted in May 2015. As well as filtering and cleaning the mine water, the reed beds will provide a valuable new habitat for wildlife.

Laboratory and field scale tests have shown that up to 99% of the iron should be removed by the treatment plant, with the local economic benefits of raising the quality of the river and foreshore predicted to be around £10.5 million over 25 years. This significantly outweighs the predicted lifetime cost of building and running the treatment plant (~£7m).

Benefits of remediation:

  • The Saltburn Gill and Skelton Beck will no longer be polluted, and the risk of a catastrophic breakout of minewater will be reduced.
  • The aesthetic, ecological and recreational value of Saltburn Gill, Saltburn Beach and the Saltburn Gill Nature Reserve will be improved.
  • Improved bathing water quality on Saltburn beach, encouraging recreation that contributes to the local economy.
  • The water body will achieve good chemical and ecological status as required by the Northumbria River Basin Management Plan.

Monitoring surveys and results

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Lessons learnt

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Image gallery


Mine discharge point
Impact on the Saltburn Gill stream
Impact on the Saltburn Gill stream
The Saltburn Gill joining the Skelton Beck in Saltburn
Saltburn Gill joining the Skelton Beck - before treatment
Crystal clear Saltburn Gill now that all four settlement ponds are on line (25 Sept 2015).
Aerial photo of the lower end of the Saltburn Beck
Saltburn aeration cascade, part of the minewater treatment system
Saltburn settlement ponds, foreground, with reed bed and drying lagoon behind
Diagram showing the general layout of the minewater treatment scheme
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Catchment and subcatchment

Catchment

River basin district Northumbria
River basin Tees

Subcatchment

River name Saltburn Gill Catch trib of North Sea
Area category 10 - 100 km²
Area (km2)
Maximum altitude category 200 - 500 m
Maximum altitude (m) 231
231 m
0.231 km
23,100 cm
Dominant geology Calcareous
Ecoregion Great Britain
Dominant land cover Arable and Horticulture
Waterbody ID GB103025071960



Site

Name Saltburn Gill Nature Reserve
WFD water body codes GB103025071960
WFD (national) typology Low, Small, Calcareous
WFD water body name Saltburn Gill Catch trib of North Sea
Pre-project morphology
Reference morphology
Desired post project morphology
Heavily modified water body No
National/international site designation UK - Site of Special Scientific Interest
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 2009/07/01
Works started 2012/12/03
Works completed
Project completed
Total cost category
Total cost (k€) 700000
700,000 k€
700,000,000 €
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 Pollution incident
Hydromorphology Quantity & dynamics of flow
Biology
Physico-chemical Oxygen balance, PH
Other reasons for the project


Measures

Structural measures
Bank/bed modifications
Floodplain / River corridor
Planform / Channel pattern
Other Construction of a Treatment Plant
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

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://www.bbc.co.uk/news/uk-england-tees-15002074 BBC, 2011. Polluted Saltburn Gill in Cleveland gets cash for clean-up
http://www.bbc.co.uk/news/uk-england-tees-20739848 BBC, 2012. Saltburn polluted stream clean-up begins
http://www.environment-agency.gov.uk/news/144707.aspx EA, 2012. Saltburn’s ochre stream set for clean up

Supplementary Information

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