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Exploratory Drilling


In October 2020 Cornish Tin Ltd (formerly Osprey Mining), began contacting local people, claiming to possess the legal right to carry out exploratory drilling on their land, though they appear to be unwilling to provide evidence of this. It is not clear what action Cornish Tin will take if a landowner refuses to sign an access agreement or refuses to allow drilling contractors onto his or her land.


In 2018 Cornwall Council made the area a mineral safeguarding zone which means future mining can take priority over other developments.

Then in July 2021, Cornwall Council granted Cornish Tin a General Permitted Development Order (GPDO) to carry out the exploratory drilling. They did this despite the fact that Cornish Tin were a dormant company with no assets. Cornish Tin were not required to place any bonds for a clean-up if they were to contaminate the area beyond present levels.

A GPDO does not adequately protect the environment. The company is required to monitor their own pollution and to decommission the boreholes themselves

Protect Wheal Vor is concerned about Cornish Tin leaving a significant quantity of abandoned boreholes, potentially worsening the existing serious groundwater contamination in the Porthleven Stream catchment area.


Cornish Tin hope that the drilling of 33 boreholes over 26 sites will result in possible second and third phases of drilling, and that if the quality of core samples is high enough, then they would be justified in developing plans for full-scale mining in Breage and surrounding parishes.

“The Project Area covers significantly more ground than the historic mining works.”    

from the Osprey prospectus (now Cornish Tin Ltd.)​


These are some of the questions Protect Wheal Vor have been asking:


Q: We asked Cornish Tin to quantify the current levels of contamination and what increases they would tolerate before suspending drilling.         

A: Cornish Tin said they operate under standard national guidelines and the relevant requirements of a General Permitted Development Order. This means they are required to monitor themselves.

Q: We questioned Cornish Tin on their abandonment plans (decommissioning designs) for each borehole.

A: They stated, on record, that the only requirement was to place a standard one-metre plug at the surface. They have subsequently stated that they will provide a ten-metre concrete plug.

Q: We requested the Environment Agency to require Cornish Tin to carry out the exploratory drilling under an Environmental Permit on the grounds that Cornish Tin are not addressing the serious pollution potential.  

A: The EA admit there is the possibility of unexpected water levels, unexpected contamination and unexpected historical mining structures, but still expect final decommissioning to be “reviewed by the operator”.

Porthleven Stream

Porthleven Stream

A view of Porthleven Harbour

Image: In summer Porthleven Stream is a magnet for young children, as it winds towards the sea at low tide.

Tin mining is a part of Cornwall’s culture and heritage. It played the major role in our rich industrial history. There are hundreds of abandoned mine-workings scattered across our landscape, proof of the trade in tin as far back as the Bronze Age. The location of many ancient mines and adits can only be guessed at, and more recent mines are not all fully documented. Most deep mines closed over 100 years ago but they still pollute our rivers, harm fish, insects and ecosystems.


Pollution from abandoned metal mines isn’t always obvious; it may not be visible and we can only tell if metals are present in rivers by measuring the water quality. Abandoned metal mines are responsible for over half the cadmium, zinc, lead, arsenic, mercury and copper found in UK rivers.


Micro-organisms at the base of the food chain that appear in contaminated streams and rivers are poisoned and cannot survive. Organisms higher up the chain become starved and die out. Insects, invertebrates, fish, amphibians, birds and small mammals lose their food source and either die or move elsewhere. This type of pollution is generally irreversible and can cover a very large area. Biodiversity is eroded and will not recover unless the water is decontaminated.


This is the situation we already have in the Porthleven Stream, the Carnon River and

numerous other waterways in Cornwall. 


The Environment Agency is responsible for monitoring water pollution in the UK. Reports show that  pollution in Porthleven Stream increased considerably between 2015 and 2016, possibly because of rainfall increase due to climate change: Porthleven Stream Catchment Area


Priority Hazardous Substances are toxic, persistent and likely to bio-accumulate. According to the EU Water Framework Directive in 2000, emissions, discharges and losses of these substances need to be ceased or phased out.  22 years later, we still have these carcinogenic substances discharging into a local stream.


Protect Wheal Vor has asked the Environment Agency to undertake and publicise baseline testing of Porthleven Stream, in spate and in drought, before Cornish Tin begin their first phase of drilling. In the absence of a positive response, Protect Wheal Vor has commenced water sampling from our local streams to establish a baseline.

A table of the high heavy metal concentrations in Porthleven Stream

Porthleven Stream is the second most polluted waterway in Cornwall.(Reason: Abandoned Mine)

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