Alexrrc at 10:16, 24 May 2017

2017-05-24T10:16:23Z

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	}}		}}
	{{Motivations		{{Motivations
	\|Specific mitigation=~~Old mining works~~		\|Specific mitigation=Pollution incident, Mine drainage metal concentrations
	\|Physico-chemical quality elements=PH, Nutrient concentrations,		\|Physico-chemical quality elements=PH, Nutrient concentrations,
	}}		}}

Alexrrc at 10:50, 23 May 2017

2017-05-23T10:50:18Z

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	{{Case study status		{{Case study status
	\|Approval status=~~Draft~~		\|Approval status=Approved
	}}		}}
	{{Location		{{Location

Alexrrc at 10:49, 23 May 2017

2017-05-23T10:49:32Z

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	}}		}}
	{{Measures		{{Measures
	\|Wider stakeholder / citizen engagement=inverte-brate analysis,		\|Management interventions=Remediation Treatment
			\|Wider stakeholder / citizen engagement=inverte-brate analysis, Improving water quality
	}}		}}
	{{Hydromorphological quality elements header}}		{{Hydromorphological quality elements header}}

Alexrrc at 10:48, 23 May 2017

2017-05-23T10:48:08Z

← Older revision		Revision as of 10:48, 23 May 2017
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	\|Physico-chemical quality elements=PH, Nutrient concentrations,		\|Physico-chemical quality elements=PH, Nutrient concentrations,
	}}		}}
	{{Measures}}		{{Measures
			\|Wider stakeholder / citizen engagement=inverte-brate analysis,
			}}
	{{Hydromorphological quality elements header}}		{{Hydromorphological quality elements header}}
	{{End table}}		{{End table}}

Alexrrc at 10:47, 23 May 2017

2017-05-23T10:47:47Z

← Older revision		Revision as of 10:47, 23 May 2017
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	{{Motivations		{{Motivations
	\|Specific mitigation=Old mining works		\|Specific mitigation=Old mining works
			\|Physico-chemical quality elements=PH, Nutrient concentrations,
	}}		}}
	{{Measures}}		{{Measures}}

Alexrrc at 10:46, 23 May 2017

2017-05-23T10:46:11Z

← Older revision		Revision as of 10:46, 23 May 2017
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	\|Project started=2013/07/01		\|Project started=2013/07/01
	}}		}}
	{{Motivations}}		{{Motivations
			\|Specific mitigation=Old mining works
			}}
	{{Measures}}		{{Measures}}
	{{Hydromorphological quality elements header}}		{{Hydromorphological quality elements header}}

Alexrrc at 10:44, 23 May 2017

2017-05-23T10:44:29Z

← Older revision		Revision as of 10:44, 23 May 2017
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	\|Invasive species present=No		\|Invasive species present=No
	}}		}}
	{{Project background}}		{{Project background
			\|Project started=2013/07/01
			}}
	{{Motivations}}		{{Motivations}}
	{{Measures}}		{{Measures}}

Embellamy at 09:54, 5 January 2017

2017-01-05T09:54:32Z

← Older revision		Revision as of 09:54, 5 January 2017
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	\|Partner organisations=The Coal Authority (UK),		\|Partner organisations=The Coal Authority (UK),
	\|Multi-site=No		\|Multi-site=No
	\|Project summary=The Carnon River catchment is located in a region of Cornwall historically renowned for tin and copper mining activities. It flows through an area described in the 19th century as ‘the richest square mile anywhere on		\|Project picture=Carnon County Adit.jpg
	earth’ and is now part of the Cornish Mining World Heritage Site http://www.cornish-mining.org.uk/areas-places-activities/gwennap-kennall-vale-and-perran-foundry). Mining in the catchment started with simple tin streaming to exploit the alluvial tin deposits along the river. By the early 18th century, the area became one of the most heavily mined, with deep workings across the region exploring the rich mineral lodes for tin, copper, arsenic, silver and lead. Some of the workings associated with Wheal Jane and Mount Wellington mines were extended underneath the river itself at a very shallow depth – just a few metres below the surface.		\|Picture description=The County Adit
			\|Project summary=The Carnon River catchment is located in a region of Cornwall historically renowned for tin and copper mining activities. It flows through an area described in the 19th century as ‘the richest square mile anywhere on earth’ and is now part of the Cornish Mining World Heritage Site http://www.cornish-mining.org.uk/areas-places-activities/gwennap-kennall-vale-and-perran-foundry). Mining in the catchment started with simple tin streaming to exploit the alluvial tin deposits along the river. By the early 18th century, the area became one of the most heavily mined, with deep workings across the region exploring the rich mineral lodes for tin, copper, arsenic, silver and lead. Some of the workings associated with Wheal Jane and Mount Wellington mines were extended underneath the river itself at a very shallow depth – just a few metres below the surface.

	The entire length of the river is impacted by historic mining, as are both major tributaries, with numerous individual sources. The headwaters around Chacewater contain several historic mining and processing sites, notably Wheal ~~Daniell~~. Further downstream at Twelveheads, the St Day Stream joins, carrying drainage from the Wheal Maid mine and tailings dam as well as other mineworkings in the Poldice Valley. Below Twelveheads, the County Adit discharges into the Carnon. This is not associated with one particular mine, rather it drains a huge heavily mined area to the west of the river. Construction of the Great County Adit started in 1748, and it is made up of a network of tunnels nearly 40 miles in length, draining over 100 individual mines. Recent data suggest County Adit contributes 70-80% of downstream loadings of		The entire length of the river is impacted by historic mining, as are both major tributaries, with numerous individual sources. The headwaters around Chacewater contain several historic mining and processing sites, notably Wheal Daniel. Further downstream at Twelveheads, the St Day Stream joins, carrying drainage from the Wheal Maid mine and tailings dam as well as other mineworkings in the Poldice Valley. Below Twelveheads, the County Adit discharges into the Carnon. This is not associated with one particular mine, rather it drains a huge heavily mined area to the west of the river. Construction of the Great County Adit started in 1748, and it is made up of a network of tunnels nearly 40 miles in length, draining over 100 individual mines. Recent data suggest County Adit contributes 70-80% of downstream loadings of
	cadmium, nickel, copper and zinc, and effectively 100% of arsenic and iron. The average annual loads from the adit are: Cd 20 kg; Ni 570 kg; As 1,500 kg; Cu 1,600 kg; Zn 13,700 kg; Fe 80,000 kg.		cadmium, nickel, copper and zinc, and effectively 100% of arsenic and iron. The average annual loads from the adit are: Cd 20 kg; Ni 570 kg; As 1,500 kg; Cu 1,600 kg; Zn 13,700 kg; Fe 80,000 kg.

	~~There are large areas of mine spoil along~~ the ~~river valley sides which are almost certainly causing diffuse impacts in wet weather~~. ~~For example~~, ~~monitoring by the Environment Agency showed that~~ the Wheal ~~Maid~~ tailings dam ~~is causing serious environmental impacts~~ and ~~it has therefore been included on~~ the ~~inventory~~ of ~~abandoned mine waste facilities required~~ by the ~~EU Mining Waste Directive (http://apps~~.~~environment~~-~~agency~~.~~gov~~.~~uk/wiyby/139297~~.~~aspx)~~.		Further downstream, the biggest tributary, the Hicks Mill Stream, enters the main Carnon. This drains a very heavily mined area on the outskirts of Redruth and contributes 20-25% of loadings of cadmium, copper and zinc. Also here at Bissoe is the Wheal Jane mine site and tailings dam. Wheal Jane was the last operating mine in the area, but when it finally closed in 1991, the dewatering pumps were removed and the workings flooded. In January 1992 a massive uncontrolled release of highly acidic minewater occurred through the Nangiles adit portal. This became one of the most notorious pollution incidents in South West history with a large area of the Fal Estuary stained bright orange by the resultant plume. Although the effect was determined to be short-term, options for long term treatment of the Wheal Jane minewaters needed to be explored. Passive treatment was trialled but ultimately found to be inadequate and since 2000, a full scale treatment plant has operated at the mine site, discharging treated minewater into the Carnon via the Clemmows Stream. This system is managed by the Coal Authority on behalf of Defra at a cost of £1.5m per year.

	~~Further downstream,~~ the ~~biggest tributary~~, ~~the Hicks Mill Stream~~, ~~enters the main Carnon. This drains a very heavily mined area on the outskirts of Redruth and contributes 20-25% of loadings of cadmium~~, copper ~~and~~ zinc~~. Also here at Bissoe is the Wheal Jane mine site~~ and ~~tailings dam. Wheal Jane was the last operating mine in the area, but when it finally closed in 1991~~, ~~the dewatering pumps were~~		The whole river length from headwaters to tidal limit fails the environmental quality standards (EQS) for cadmium, nickel, arsenic, copper, zinc and iron, and so fails to achieve good status for the South West River Basin Management Plan. Typical annual average magnitude of failure in the Carnon at the compliance monitoring site at Bissoe are:
	~~removed~~ and the ~~workings flooded. In January 1992 a massive uncontrolled release of highly acidic minewater occurred through the Nangiles adit portal. This became one of the most notorious pollution incidents in~~ South West ~~history with a large area of the Fal Estuary stained bright orange by the resultant plume~~. ~~Although the effect was determined to be short-term, options for long term treatment~~ of the ~~Wheal Jane minewaters needed to be explored. Passive treatment was trialled but ultimately found to be inadequate and since 2000, a full scale treatment plant has operated~~ at the ~~mine~~ site~~, discharging treated minewater into the Carnon via the Clemmows Stream.~~		• Cd = 22x EQS
			• Ni = 4x EQS
			• Cu = 153x EQS
			• Zn = 103x EQS
			• Fe = 2x EQS

	~~WFD Compliance~~		Invertebrate surveys here exhibit ‘poor’ or ‘bad’ status. The river is effectively dead in terms of ecology.
	The whole river length from headwaters to tidal limit is non-compliant with Water Framework Directive Standards to varying degrees for cadmium, nickel, arsenic, copper, zinc and iron. The WFD monitoring site at Bissoe is below all the main impacts and most recent mean levels here are: Cd 1.72ug/l (EQS = 0.09); Ni 35ug/l (EQS = 20); As 80ug/l (EQS = 50); Cu 123ug/l (bioavailable EQS ~2); Zn 1054ug/l (bioavailable EQS ~12); Fe 2578ug/l (EQS = 1,000).

	All of these are non-compliant, but copper and zinc concentrations are approximately 80-90 times the standard for good status, whilst cadmium (a Priority Hazardous Substance under the WFD) concentrations are about 20 times the level needed to achieve good status. Invertebrate surveys here ~~have also exhibited~~ ‘poor’ or ‘bad’ status. The river is effectively dead in terms of ecology.

	Remediation		Remediation
	Treatment and management of the Wheal Jane minewaters will continue under the Coal Authority with ~~funding from Defra~~. ~~However,~~ because of the extent, number and nature of other ~~abandoned metal mines impacting~~ the catchment, ~~we do not currently know if it will~~ be technically ~~feasible to clean up the river at an acceptable cost~~.		Treatment and management of the Wheal Jane minewaters will continue under the Coal Authority. We're working with the Coal Authority to explore the feasibility of treating some of the County Adit discharge in the existing Wheal Jane system, as well as other options for improving water quality in the Carnon in the medium to long term. It is possible that because of the extent, number and nature of other sources within the catchment, further measures may be deemed technically and/or financially unfeasible.
	}}		}}
	{{Image gallery}}		{{Image gallery}}

Hazel Wilson at 12:54, 2 November 2015

2015-11-02T12:54:24Z

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	\|Subcatchment=Upper Carnon River		\|Subcatchment=Upper Carnon River
	}}		}}
	{{Site}}		{{Site
			\|WFD water body code=GB108048001160
			\|WFD water body name=Upper Carnon River
			\|Heavily modified water body=No
			\|Protected species present=No
			\|Invasive species present=No
			}}
	{{Project background}}		{{Project background}}
	{{Motivations}}		{{Motivations}}

Hazel Wilson at 12:53, 2 November 2015

2015-11-02T12:53:44Z

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	{{Toggle button}}		{{Toggle button}}
	{{Toggle content start}}		{{Toggle content start}}
	{{Case study subcatchment}}		{{Case study subcatchment
			\|Subcatchment=Upper Carnon River
			}}
	{{Site}}		{{Site}}
	{{Project background}}		{{Project background}}

Case study:Carnon River: Abandoned Metal Mines - Revision history