dave cooke the coal authority - sclf.co.uksclf.co.uk/conference/2018/9 - dc - 20180905-sclf... ·...
TRANSCRIPT
Dave CookeThe Coal Authority
WAMM! Partnership (no Coal!)
main funder and programme owners
lead on catchment characterisation, impacts and priorities.
lead on scoping, feasibility, design, build and operation of schemes.
• 105 Water bodies affected by abandoned metal mines
• 1500km of rivers impacted by metals causing good status failures for chemicals
• 11% of groundwater bodies in poor status.
• 7 of 11 River Basin Districts affected.
• Fe, Ni, Pb, Cd, Cu, Zn, Al, Mn…all mined
• Approach driven by WFD, feeding into
RBMP, but no legal liability for past
operators / current owners (of abandoned
metal mines).
WAMM! Metal Mines
WAMM! Mine Waste Directive Inventory
WAMM! and Contaminated Land
Traditional contaminated land terminology:
Characterisation
Scoping and Optioneering
Treatment Techniques
Diffuse Sources
Dissolved Sources
Monitoring and Improvements
WAMM! Characterisations and CSMs
EA Characterisation Reports
Monitoring and Assessment Focus
Diffuse and Dissolved Sources and Mechanisms
Prioritisation and Cost Benefit Analysis
WAMM! Conceptual Models
WAMM! Conceptual Models
Optioneering – the WAMM Toolbox
Part of Scoping and Feasibility
Constrained by:
Geographical and Environmental Limits
Mine water and spoil geochemistry
Financial
Political and competing policy objectives
• 75 individual waterbodies investigated, with a current portfolio of 40+ active projects across England
• Because no legislative driver, schemes are assessed on the basis of estimated benefits to cost ratios:
• Average for first 18 schemes B:C 3
• Top 6 schemes B:C >5
WAMM! Works to date
WAMM! Treatment Techniques
Water (Dissolved Sources):
Reaction, absorption and filtration / settling
Reaction can be direct (HDS type water treatment) or indirect (VFP /
VFR / HFR)
Absorption (activated carbon type)
Electro-precipitation (electro-chemical reaction).
All based on the concentration of metals into the solid phase (with
subsequent disposal / recovery?!).
Treatment continued
Solids (Diffuse sources):
Typically, deposited mine spoil, erosion products (river sediments), mine
processing residues.
Traditional engineering techniques applicable:
Containment, capping, surface water management,
erosion protection.
All about prevention of leaching and physical transport of solids into the
water course.
WAMM! Case Studies(with the promised photos)
Saltburn Pump and Treat (Aerated Iron Precipitation)
Force Crag Passive Treatment (Compost VFP)
Nent Check Weirs – Dredging and New Build (Dig and Dump!)
Foreshield Shaft protection (Gabion Wall)
Carrshield Tailings Dam (Retaining Wall, Capping and Interceptor Drain)
Wheal Jane (HDS and Clarifiers)
Remediation of Ironstone Mine discharge polluting stream, SSSI and bathing beach.
£10.5 million benefits into the local economy over the next 25 years
Removes in excess of 98% of metals. (100 t Fe/year)
Removed the risk of a catastrophic mine water break out
WAMM! So far so good - Saltburn
Force Crag
Worked for zinc, lead and barytes from 1835 until 1991
Pollution affecting local becks, river and Bassenthwaite lake. High levels of zinc, cadmium, lead and copper
A full scale passive treatment scheme now operational.
Removal of >95% of Metals
WAMM! So far so good – Force Crag
Force Crag and Coledale
Environmental Outcomes
River Nent - New check weir (Nenthall)
Metals removed: forecasted 1.4t Zinc/yr
Up to 60km of river improved, contributes to
Tyne estuary sediments (aim to decrease
from ~127t Zn/yr to <50t/yr)
Scheme cost: £320k
Whole life cost: £1.1m
Scheme benefit: £3 - £10m (25 yrs)
River Nent –
Dredging existing
check weirs
(Nenthead)
Metals removed: 20
– 30t Zn, Cd, Pb
Up to 60km of river
improved,
contributes to Tyne
estuary sediments
Scheme cost:
£487k
Scheme benefit: £3
- £10m (25 yrs)
WAMM! So far so good – Nent Check Weirs
Environmental Outcomes
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River Nent – Foreshield shaft
Metals removed: not quantified
Cost: £187k
Benefits: prevented river eroding metal-
rich soil and being diverted into the Nent
Force Level; protects calaminarian SAC
River West Allen – Dressing floor diffuse
pollution prevention
Metals removed: not quantified
Cost: £450k
Benefits: together with Carrshield tailings dam,
contributes up to 5% of Zn entering Tyne estuary
WAMM! So far so good – Foreshield and Carrshield
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River West Allen:
• More than 40km of river polluted with metals
• 6.5km downstream: up to 126x zinc EQS (52x cadmium)
• 27km downstream: up to 8x zinc EQS (6x cadmium)
• Up to 25% of zinc entering Tyne estuary (sediments) are from West Allen
• Fish and river flies (invertebrates) impacted for several km
• Environmental and economic benefits >£30m over 25 years
• Barney Craig mine water: key source of metals
• Carrshield tailings: significant risk of imminent collapse
• 48,000 cubic metres containing >60 tonnes zinc and 47 tonnes lead
• Scheduled ancient monument (Victorian wall, tailings in 1950s)
• Mining Waste Directive inventory: causing serious environmental harm (run-off)
WAMM! So far so good – Carrshield Tailings Dam
Carrshield Downstream
Wheal Jane Treatment Plant
Wheal Jane Consequences
Nent Haggs Passive Treatment Scheme (Water Transfer and VFP)
West Allen Check Weir (Sediment retention)
Coalcleugh (Surface water management and floodplain lowering)
Ashfoldside Drainage Interception (Surface water management)
Gwindra Pilot Scheme (4 pond gravity VFR)
Tees Swale Diffuse (Green engineering and erosion control)
Cambokeels Passive Treatment (In-situ VFP)
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WAMM! Future Plans
Nent Haggs Visualisation
WAMM sites in YorkshireWAMM! Future Plans
Environmental Outcomes
Saltburn
Water treated: 0.82million m³
Metals removed: 102t of Fe
2 km of river improved.
Force Crag
Water treated: 65,000 m³
Metals removed: 175kg of Zn
10 km of river improved.
Bassenthwaite Lake SAC now
meets EQS
Wheal Jane
Water treated: 5.34million m³
Metals removed: 600t Cd, Ni, Zn,
Cu, As, Fe
8km of watercourse improved, Fal
Estuary SAC protected
WAMM! Headlines
WAMM! Ongoing
Thank You