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Author Milwr Tunnel & Olwyn Goch news
Blober

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Joined: 16/12/2012
Location: Anglesey

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Posted: 11/01/2018 14:08:27
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Its probably not nearly as bad as it was anymore now they've started reconditioning the shafts?

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ttxela

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Joined: 04/09/2007
Location: Cambs

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Posted: 11/01/2018 14:20:18
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ChrisJC wrote:

ttxela wrote:


Still not been down Milwr tunnel or the associated working though……


You should organise a trip for WCMS Alex.

Chris.


That could be a plan Smile

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ant89

Joined: 01/04/2013
Location: Wrexham

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Posted: 11/01/2018 16:40:20
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RAMPAGE wrote:

dwarrowdelf wrote:

Interesting - does anyone one know what's generating the radon in this particular case? Smartass


No, I must admit I was only half listening and it was 10+ years ago. Something about the limestone shales there containing something radioactive. He also talked about all the sea-shell fossils in the roof being upside down, some natural event killed them all so the floated to the bottom of the see upside down dead. There was some connection to that event and the radiation. But I'm only saying what I heard, it's not my field.


A quick look on wikipedia suggests that it's uranium, as Radon occurs at some point as uranium decays to lead.
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ant89

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Posted: 11/01/2018 16:43:20
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ttxela wrote:

ChrisJC wrote:

ttxela wrote:


Still not been down Milwr tunnel or the associated working though……


You should organise a trip for WCMS Alex.

Chris.


That could be a plan Smile


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 Cool
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BertyBasset

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Joined: 13/12/2007
Location: Caernarfon, North Wales

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Posted: 11/01/2018 17:59:29
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Just had a proper look at Cris's mine site, and it's got tons of useful stuff.

Also done a bit of radon research...

The N Wales limestones (and Derbyshire) contain hydrocarbon masses that are enriched in uranium. Both the hydrocarbons and lead would have been present in the brines leached from sedimentary basins and precipitated within the limestone.

Robin
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John Mason

Joined: 22/09/2008

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Posted: 11/01/2018 18:05:48
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dwarrowdelf wrote:

Interesting - does anyone one know what's generating the radon in this particular case? Smartass


The lodes carry bitumen in places in solid black lustrous masses to several centimetres, usually embedded in calcite. The bitumen in turn contains small inclusions of uraninite. Bitumen content varies strongly from lode to lode but I wouldn't sleep in an unventilated heading near a rich patch! I imagine the air fairly blasts through the main tunnels down there though, thereby flushing the system constantly.
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John Mason

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Posted: 11/01/2018 18:15:45
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These references may be of interest:

Parnell, J., 1983 The distribution of hydrocarbon minerals in the Welsh Borderlands and adjacent areas. Geological Journal, 18, 129-139.

Parnell, J., 1988 Mineralogy of uraniferous hydrocarbons in Carboniferous-hosted mineral deposits, Great Britain. Uranium, 4, 197-218.

Eakin, P.A. & Gize, A.P., 1992 Reflected-light microscopy of uraniferous bitumens. Mineralogical Magazine, 56, 85-99.
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staffordshirechina

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Joined: 15/11/2009
Location: North Staffordshire

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Posted: 11/01/2018 18:21:24
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Blober wrote:

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.......
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dwarrowdelf

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Joined: 09/02/2011
Location: Lost in Cwmorthin...and Oakeley too !!

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Posted: 11/01/2018 19:29:27
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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 Thumb Up

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ttxela

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Joined: 04/09/2007
Location: Cambs

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Milwr Tunnel & Olwyn Goch news
Posted: 11/01/2018 20:38:33
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ant89 wrote:



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 Cool


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

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Blober

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Posted: 12/01/2018 00:44:30
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staffordshirechina wrote:

Blober wrote:

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. Laugh

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Graigfawr

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Posted: 13/01/2018 15:24:23
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Edd wrote:

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 Laugh


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.
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RJV

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Joined: 16/03/2008
Location: Cleveland

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Posted: 13/01/2018 15:48:08
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Edd wrote:

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 Laugh

& filled out water bottles downstream of Rhydymwyn on another long trip... Smile
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John Lawson

Joined: 09/12/2010
Location: Castle Douglas Dumfries & Galloway

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Posted: 13/01/2018 20:44:58
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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.
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Graigfawr

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Posted: 13/01/2018 21:50:54
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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.
IP: 5.66.108.74 Edited: 13/01/2018 22:00:23 by Graigfawr
mineskipper

Joined: 29/03/2012

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Posted: 17/01/2018 10:27:14
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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

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RAMPAGE

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Joined: 01/03/2015
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Posted: 17/01/2018 10:59:19
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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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ttxela

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Posted: 17/01/2018 12:23:49
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Thanks Martin Thumb Up

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dtyson

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Joined: 17/11/2008
Location: wirral

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Posted: 17/01/2018 13:10:30
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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
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Ian A

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Posted: 17/01/2018 14:20:27
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+1 Thank you

Big Grin

Ian

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