Its probably not nearly as bad as it was anymore now they've started reconditioning the shafts?

Likely to be worse at the moment. They are positively ventilating their area. So the pressure stalls the natural ventilation and causes upstream stagnation of the air.

Hence the warnings given.......

Many thanks for the info and references. Wondering if the water flow would in theory help push the air through to any extent?

Also really enjoyed the through trip video - great :thumbup:

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wait until the summer, likely to be less water to walk through (likely, but not garenteed), and a train may be fully functional by then too 8-)

Sounds good, I may well be in touch later in the year. I can't arrange anything much for the Summer at the moment as I've got a trip abroad I haven't got dates confirmed for yet

Its probably not nearly as bad as it was anymore now they've started reconditioning the shafts?

Likely to be worse at the moment. They are positively ventilating their area. So the pressure stalls the natural ventilation and causes upstream stagnation of the air.

Hence the warnings given.......

Well, i've had a good life. :lol:

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A few of us camped over night in the limestone workings a few years back and 2 of us have had children since then so no lasting effects :lol:

The main risk is an increased likelihood of lung cancer.

A keen caving friend died of lung cancer and he attributed it to radon exposure in caves over 50+ year period. He was a lifelong non-smoker and had never worked with radioactive materials, carcinogenic dusts, etc, and lived in a region not noted for radon issues in buildings. Its only an isolated anecdote but it gave me pause for thought about continuing to camp underground which I have done a few times, mainly to avoid horrible winter weather on surface.

A few of us camped over night in the limestone workings a few years back and 2 of us have had children since then so no lasting effects :lol:

& filled out water bottles downstream of Rhydymwyn on another long trip... 🙂

Graigfawr,
What about increased risks of lung cancer from passive smoking?
We live in a area where Radon, is associated with our local granodiorite, and for a while their was a program to fit ventilation fans in cellars, of old houses.
However I cannot remember anyone circuming to lung cancer caused by Radon gas.

My initial post was in response to Edd's humorous post about still being able to have a family despite exposure to radon in mines: I was observing that the main risk arising from exposure to the sorts of levels of radon encountered in mines was an increased lung cancer risk rather than a decrease in the ability to have a family.

There have been a number of articles in Descent magazine over the years on this topic which include calculations of possibly how much an individual caver's risk is increased, with, if I recall correctly, separate calculations for smokers and for non-smokers, and information on other causes of lung cancer, including radon exposure from natural sources such as living in certain regions where granitic rocks occur. I don't have them to hand but recall that there seemed to be an increased risk if you spent quite a bit of time caving, especially in certain areas or certain caves.

The anecdote from my deceased friend was included because it seemed to be a possibility and seemed worth mentioning as some of us spend additional time underground by camping sometimes.

For 'caves' in the above, you can also read 'mines' of course. Aditnow members from Cornwall have previously posted about issues in some of their region's mines, from a variety of causes.

I have no specific knowledge on the subject beyond a half-remembered reading of these Descent articles a few years ago but thought it worth mentioning so that aditnow members can make their own decisions as I believe that some mines can have radon levels higher than the 'average' cave and cumulative and long term exposure might be significant - e.g. my caving and mining diary tells me I've spent over 600 days underground; others on aditnow are much more active than that.

I am the Mine Manager (working for Wardell Armstrong on behalf of United Utilities) for the ongoing works at Caeau Shaft and in the Milwr Tunnel and I would like to explain the situation with regards to the current access to the tunnel.

As some of you will know, the HSE has the view ‘that once a mine, always a mine’ and therefore as soon as we start any work on the tunnel, it has to be designated as a working mine. For the duration of the current works, the extent of the ‘mine’ (as notified to the HSE) extends from Pen y Bryn Shaft to the portal. Prior to starting the works we contacted Grosvenor CC, NWCC and UCET in order to inform them of this and that there should be no caver access downstream of Pen y Bryn Shaft – this is also as per an agreement with Grosvenor CC. Unfortunately, the posting of the video of the 2016 through trip on UK Caving has rekindled interest, hence this post to clarify matters and provide some further information.

We would therefore re-iterate that, for the duration of the works (until the end of 2018) there should be no access by cavers downstream of Pen y Bryn Shaft. In any event, the portal is located on private property and there is no agreement for cavers to exit the tunnel here. The area is securely fenced and any damage to the fence, gate or locks could be considered as criminal damage.

The potential hazards of entering the tunnel should also not be under-estimated. Water flows in the tunnel average about 1m3/sec and water levels can rise quickly following rainfall. Walking against the flow for any significant distance can then be very arduous, and impossible in some conditions. There are points in the tunnel where falls have occurred, which have the potential for further collapse and other points where the water can back up to the roof. At worst you could find yourself not being able to proceed downstream with retreat being very long and difficult, if not impossible, back upstream.

There has been mention of the high radon levels in the tunnel. Although levels vary significantly due to the effect of weather conditions on the ventilation in the mine, we have measured naturally occurring radon concentrations up to 40,000 Bq/m3. In terms of dose this is equivalent to approximately 1mSv per day spent underground. To put this in context, the average annual radiation dose in the UK is 2.7mSv and the annual dose limit for a radiation worker in the UK is 20mSv. As such, when undertaking inspections or work in the tunnel, we install ventilation fans that dilute the radon in the working area and also put the tunnel under positive pressure in order to reduce the flow of radon from the old workings. A result of this, however, is that radon concentrations further upstream in the tunnel may be increased over ‘normal’ levels.

The current team have been inspecting and repairing the tunnel since 2010 and so have developed a keen interest in it. We are happy to work with the caving community but it must be appreciated that access to the tunnel must be undertaken responsibly. The repair works are to ensure the stability of the tunnel and the continued free flow of water out of the tunnel. The works are, therefore, of benefit to all and we would therefore ask for you co-operation.

Many thanks
Martin Downing

Martin

Just wanting to thank you for that very informative and helpful post. Sometimes the information that filters down to some of us has been through a number of people and what we get isn't always accurate, so great to read something so from-the-horses-mouth, so to speak.

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Thanks Martin :thumbup:

Thanks for the clarification Martin, I have posted your message on the UKCaving site which will reach other interested parties with a view to making the current situation clear.

Dave

+1 Thank you

;D

Ian

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Thanks Martin for all this, much appreciated.
:thumbsup:

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Really good to hear the truth rather than all the rumours and counter rumours of late.
One of these days I hope to visit and find out what is at the bottom of Olwyn Goch whose spinning wheels on the headgear I used to see every morning going to work - and wonder...
Many thanks for the information, Martin.
Clive

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Martin,

Many thanks for helping to provide clarity. It is most pleasing to read that you are willing to work with the caving community, and as such I'd hope that the caving community will work with you as to do so would surely benefit all parties.

Anthony

Thanks Martin,
It is good to see that the U/g manager working for a utility company, has taken the time to read through our comments.
We on this site appreciate that,
once again, thanks and we hope you will update us on AN as your work, progresses.