Ogof Nant Rhin Collaspe

[manrabbit]

Anyone thinking of doing a pull through trip in Ogof Nant Rhin will need to open the bottom entrance first as there has been a collapse about 6 metres in from the entrance just where the passage turns right and climbs over the little step. This might be easily cleared from the inside but I wouldn't count on it.

Huw

 

[mikem]

It would be a good idea to put in some shoring as well, I did suggest it last year, but unfortunately I only visit every 5 years or so!

Mike

 

[NigR]

I seem to recall that this was one of Alkapton's favourite trips - remember the discussion about fixed ropes some time ago?

Haven't seen any posts from him for a while - maybe someone ought to go and check that he isn't still trying to dig his way out!

 

[manrabbit]

:-\ Something brought the roof down, maybe it was his walking stick!

Alkapton, if your still alive and reading this please let us know.

 

[shortscotsman]

I was there in November last year during the very cold period - the entrance few metres was very heavily iced presumably from water percolating down. I wasn't surprised that it collapsed in the spring - the freeze thawing would have really been loosened up the rock.

 

[mrodoc]

What's a collaspe? Something you get without a spell check?

I'll get me coat.

 

[Alkapton]

Only now do I see my name taken in vein :-\

I last went on a through trip in autumn I think,  I know the corner with the scaff at nant rhin enterence because about second time I came out big bits fell on my back there, well enougthy not to be comfortable, I also know the hard winter we had damaged a few enterences by here, but I havn't looked at Nant Rhin yet this year.

If it needs attention and there are people with scaff and shoring skills I'll happily lend a hand

 

[frank]

the 2009? collapse was repaired by Adrian Fawcett and others and a good job was done?. However during a recentish trip there in june i noticed that the stream had washed away the streamed under several of the legs of the scaffold?. Obviously this will weaken the structure ? The original collapse was probably caused by the left hand wall pushing in ( i abandoned a pre original collapse here as this event was in progress) I guess that there are a few  possible solutions ? to my eye some sort of bracing at floor level for the scaffold would probably prevent the problem reoccurring ?maybe someone else fancies having a look and voicing an opinion ?..

or maybe there will just be lots of sarcasm?.

 

[damian]

I've just mentioned this to Adrian Fawcett. As it happens I think he has the odd spare day on his hands this week, so I wouldn't be surprised if he didn't go and have a look.

 

[John S]

Photos of the area in Nant Rhin are on -
http://a465gilwern2brynmawr.files.wordpress.com/2014/02/dd553-cave-mapping.pdf

The collapse is at st1 and  st2. see page 9 and 24/25. (st2 is basically directly above st 1)
photo 7196 show loose stuff on the left and this may have been the stuff that has moved.
(golf balls were placed to show the stations)

 

[Caver Keith]

I think re-excavating the original entrance would be the best option. It would stop anyone not having the physique of the racing snake doing the trip, but hey ho - you can't have everything.

 

[frank]

i think i was more looking at 7194  where the ground below the leg has been washed away?think a few of the other legs are resting on air and therefore not very effective  i.e. the wall will push in?.then again i am not an expert..

 

[John S]

Adrian had a look this weekend and  placed a larger block under that scaffold leg. He also had a look at where there had been collapse a couple of years back and that seems to to OK at present. The old way in/out would be damp but its only a bit of silt that is making it tight and you could probably get out if you needed to. (If you fitted through the previous squeezes.)