Thrupe Lane Swallet

[Maj]

Update regarding Thrupe Lane Swallet (TLS).
As you will find there is an article in the latest copy of Descent (255) about the digging of Hobnail Hole which now connects with TLS. The break through point is in Upper Butts' Chamber. To get down from Upper Butts' Chamber into Butts' Chamber requires climbing down one of two routes, both of which are over unstable boulders (the floor of both Butts' and Upper Butts' Chambers consist of one large boulder slope). The preferred route to the right (left is more exposed and loose) involves climbing over three boulders, the centre one of which is bridged across the other two with a large cavity below and behind. From below it would be obvious that care would be required, but from above you wouldn't be aware of the perched nature of the boulders until it's too late. We are currently building up the cavity below with cemented rocks and a steel beam (steel beam due to be installed tonight) to stabalise the boulders.
Hobnail Hole won't be available for general trips until the stabalisation work is completed. Since Hobnail is visible from the road and has a tempting fixed ladder and vertical free climb below, the plan is to fit a CSCC padlock to keep access for cavers as easy as possible (the status quo will remain for TLS gate).

TLS is still taking the full stream at present.
The stream can be diverted down Hobnail Hole to allow access to TLS, but we would kindly ask if you could contact us first (one of the ATLAS diggers) if you would like a trip down TLS since we are usually working down Hobnail Hole on a Fri or Sat daytime and at present on a Wed evening too, days and times may change. We may even be able to divert the stream for you prior to a trip which would give the Ferret Run and Perseverance Pot longer to drain/dry out.
If you would like to lend a hand with the cementing etc. or our other project to re-open Bone Aven down the Old Wells Road, please get in touch, you will be more than welcome.

Thanks,
Dave.

 

[mikem]

Dave, are you there over the Easter weekend?

Mike

 

[Maj]

Not sure what our plans are yet, but I'm sure if you wanted a trip over Easter between us we can timetable ourselves accordingly.

Dave.

 

[Maj]

Thrupe Lane Swallet over the Easter period.

The ATLAS Diggers will be continuing the work in Hobnail/Upper Butts' Chamber during the afternoon on Fri 14th April. When finished for the day the stream will  be diverted down Hobnail Hole and left as such until our next session on the evening of Wed 19th April.

This will mean that Thrupe Lane Swallet will be accessible during that period for any trips, weather permitting (a trip is already planned for approx 11am Sat morning). If you are planning a trip whilst the stream is entering Hobnail Hole it would be advisable to take a spade in case the dam has previously  been breached and requires a little fettling. Also we would not recommend a trip down Thrupe Lane Swallet if rain is forecast as the stream running along side the road that enters the depression and subsequently Hobnail Hole or Thrupe Lane Swallet, can react quickly and could breach the dam making an ascent of Perseverance Pot extremely aquatic if not impassable, The Ferret Run and the entrance climb will also be very aquatic.

Please do not climb above the obvious stabilisation works at the top of Butts' Chamber.  There is no restriction on access to the usual route to the Marble Streamway and ATLAS Pot.

Hobnail Hole is still undergoing stabalisation works and therefore is not yet available for general trips.

Thanks,
ATLAS.

 

[Frigbob]

Hi Dave,
What is the likely access situation for TLS this weekend (Saturday 20th May)? Thinking about a trip down High Atlas, weather permitting. Don't want to upset any digging plans or infrastructure.
Thanks,

Tim.

 

[Maj]

Hi Tim & anyone else interested in a trip down this magnificent Mendip cave.

Since the stream level is currently low we have diverted the stream down the Hobnail channel. This doesn't impede Atlas diggers access to Butts' Chamber via Hobnail Hole. Therefore so long as the stream is not overwhelming the dam, the entrance to Thrupe Lane Swallet is dry and accessible.

So have a good trip on Saturday.

Parking might be a little tight in the layby this Sat since we will be there too, so can I suggest you park towards one end or the other of the layby to maximise available parking space. But do ensure you are in the layby since quite often there are very large tractors roaming the area and they might take a fancy to the odd wing mirror ot two. If the layby is full, we can overflow into the yard just beyond the layby on the same side of the road (remember to close the gate when leaving).


The usual Atlas culprits will be luncheoning in or by the Ferret Shed on Sat before heading underground, loaded with cement and gravel etc for the continuing stabalising of the boulders in Butts' Chamber. The end is in sight and we hope it's not too long before we fit a CSCC padlock to Hobnail Hole entrance gate - watch this space! 

Regards,
Dave.

 

[Maj]

Hi,

The ATLAS diggers were at it again down Hobnail Hole to continue cementing the boulders between Upper & Lower Butts' chambers. With the Hobnail channel currently taking all of the stream, the entrance to Thurpe Lane Swallet was very dry. We did experience a slightly drippier run down through Hobnail to reach Butts', but not enough to cause a problem even on our exit after some heavy rain fall on the surface.

Whilst underground I took a look at Cowsh Crawl and as expected this was dry with no water entering from Perseverance Pot at all.

So at present, further rain fall permitting, now is a good time to take a trip down the Marble Streamway to Atlas Pot via the Ferret Run & Perseverance Pot. But obviously bearing in mind any anticipated rain fall and the likely hood of the dam being overwhelmed or breached.

Dave.

 

[obelix]

I left a rope behind on Thursday, 25m of white 10.5mm, just inside the entrance. If someone does this trip in the next few days and lives in or near Bristol, or Shipham, or Yate please collect it and pm me by Sunday night and I will collect it from you and be very grateful.
Otherwise please leave it there as I can collect it on Monday.

Even after lots of showers the entrance was really dry, not even a puddle between Slit and Perseverence, or Cowsh crawl, though there was  enough water for entertainment in Marble streamway and Atlas.  The Surface dam and drain working really well and giving confidence for a really tiring trip.
Thank you diggers.

 

[mikem]

No sign of water in West Twin Brook, so although the showers are heavy they are not overflowing the aquifer...

Mike

 

[Maj]

Hi Obelix,

I gather the rope have currently been put in the Ferret Shed, our ATLAS diggers store etc.
I'm about on Mendip and will be over that way tomorrow (Sunday) morning, so I can either leave them where you caa gain access to them or I can bring them back to the MNRS (Green Ore, near the Plough Boy pub) whichever is easiest for you.

Cheers,
Dave.

 

[Maj]

Hi Obelix,

PM's sent yesterday and today.

Cheers,
Dave.

 

[Maj]

Hi,

On Sunday I found myself over East Mendip, not really much of a surprise, but whilst heading home I drove through a torrential downpour. So I thought it an idea to go and have a look at the TLS stream. Initially the stream was only slightly up and the full flow still happily disappearing down the Hobnail sink, but then it changed quite dramatically over the next half hour or so. The stream came up and started to find ways around the dam and  sinking below the cliff face some 5m short of TLS entrance shaft. The level carried on rising and soon the dam and the sink at the end of the Hobnail channel were overwhelmed. The stream then reached the TLS gate and any debris leaves & twigs etc that washed down started to block up the gate and before long the level was 3/4 up the gate.
Although TLS is now more accessible, a careful check of the weather forecast is a must. The stream can respond quickly and make Perseverance and the entrance pitch impassable.
Hopefully some photos below.

Dave.

 

[Maj]

Hi,

Update on Thrupe Lane Swallet & Hobnail.
As soon as I receive a new CSCC padlock it will be fitted to the Hobnail entrance grill, but in the mean time 
I wouldn't consider a trip down either at present until the weather improves and stream levels drop and some clearance work carried out.
A few photos taken Sat 27th Jan.


Dave.

 

[Maj]

Re Hobnail Hole:

This does not have a CSCC padlock on it as yet. There was a plan to put one on before Xmas, but it was felt best to wait for imminent new padlocks. Since Xmas there has been substantial flooding, covering Hobnail Hole and blocking the entrance to Thrupe Lane Swallet. Also Hobnail Hole is currently under a 4ft snow drift, so Hobnail still remains unavailable until substantial clearance work has been done.

There is a plan to have a working day or weekend over there before Mendip Cave Fest to get TLS and Hobnail open for business. A rough plan is to light a BBQ and ask cavers to come over and have a social working day or two to get it all cleared.

Will post details when a plan is made.

But an idea of numbers of interested cavers would be useful 


Maj.

 

[Maj]

Latest update:-

With the recent bad weather it has been difficult to arrange a weekend to clear Thrupe Lane Swallet entrance. But last weekend four members of MNRC (Nick P, Ian B, Mark C & Dave K) spent a few hours carrying out some clearance work.

The Hobnail stream channel was partially cleared allowing the stream to be diverted down Hobnail Hole. This then enabled the clearing of TLS gate and dig out a lot of the silts, shingles & sludge that had been deposited in front of of the entrance. In all a guestimated 1 tonne of debris was shoveled and ferried up the steps in dustbins and deposited clear from where it might get washed back in. 

There is still a lot more to clear in due course, but for the time being TLS is open for business (in time for Mendip Cave Fest) weather and stream conditions permitting. 

Hobnail Hole now has a CSCC padlock on the gate and is also open subject to weather and stream conditions.

WARNING Both Hobnail & TLS can be become very aquatic and impassable when water flowing down.

Note also that we had cleared TLS gate of debris last weekend and left the stream flowing down the Hobnail channel for a TLS trip on Friday. The rain on Tues night was enough to breach the dam and wash more debris towards and half covering TLS gate.

WARNING The stream can react quickly to rainfall, I have watched the level rise from nothing entering TLS to a raging torrent in about 1/2 hr of heavy rain (scroll up to earlier post).

For information on Hobnail Hole see article in Descent issue 255 (Apr/May 2017) "Cobbling it All Together"
If planning on a trip down either Hobnail Hole or TLS, bear in mind you may need to clear debris from either gate and the Hobnail channel grill, possibly rod through the Hobnail Channel grill (5ft length of angle iron behind green shed, longer bar or drain rods might be useful), rebuild dam/divert stream.

To ensure other cavers that may arrive after you have begun your trip don't divert the stream down the entrance you have descended, leave the gate open. Although TLS entrance is free climbable, it is best laddered or SRT'd, as this will give a better indication that there is a party down there. I'd also recommend you think about a few "what ifs" ie someone fly tips grass/hedge cuttings up stream that may then wash down and block either TLS gate or Hobnail channel grill (this has happened). Kids playing in the stream, changing the course of the flow (this has happened on another dig less than a mile away). Leave a robust ETO, or you might consider someone on surface watch.

If you would like any further info about TLS, consult MU5.
For further info on Hobnail (kit requirements etc), feel free to contact myself or one of the ATLAS diggers.

Dave.

 

[tim.rose2]

Anyone able to give a current update on Thrupe?  Is the cave accessible / what are current water levels like?  Considering a trip on Sunday as there's only a bit of light rain on Saturday forecast between now and then at the moment.  Would be looking at the usual trip down Perseverance pot, marble stream-way and atlas

Plan B is go play somewhere else! 

Thanks in advance.

 

[mikem]

Wookey was relatively wet tonight, which ain't a good sign for Thrupe...

 

[Maj]

The gate on Thrupe Lane Swallet is half choked with stream washed debris and will require clearing before access gained. The Hobnail channel requires digging out again as it will every couple of years, although it can still currently take a stream.

A trip down TLS will depend on a couple of things:-
1. Whereabouts the surface stream is sinking.
2. Which route ie Railway Series or Perseverance/Slit Pot.

The stream sinks in various locations between the Ferret Shed and TLS gate which include:-
Hobnail Channel, large depression to the right of the stream (facing down stream), where the stream first meets the cliff face, under the rock & log dam by the cliff face, various points along the cliff face before it reaches the gate. 

If all the stream is sinking before the rock & log dam it doesn't seem to enter the entrance shaft and Ferret Run and hence Perseverance should be okay.
As soon as the stream goes beyond the rock & log dam this water emerges in bottom of the entrance shaft and will make perseverance wet at best and impassable at worst.

If planning a trip down TLS I would recommend ensuring that a reasonable dam is re-established diverting all of the stream down the Hobnail Channel but also suitable to cope with any increase due to further possible run off.
This time of year I would also recommend rigging a ladder down into King Cobble Hall by entering Hobnail Hole, such that if you find on your return Perseverance is too wet to climb you have an alternative exit. Hobnail will remain passable albeit wet for a couple of short climbs except under extremely wet conditions.

The Railway Series remains accessible provided the entrance pitch is not impassable due to water flowing through the gate and straight down the entrance.


Another interesting point of note is that since the stream no longer goes through the pipe under the road before the Ferret Shed, Chimney Pot (up slope from Bleak Hall on route to Wuthering Heights etc) seems to now be permanently dry. Making trips to High Atlas and Wuthering Heights more reliable.

Hope this helps,
Maj.

 

[Maj]

To add:-
We have had a lot of rain in the last few days.
I can pass by TLS later today and update stream conditions accordingly.

Maj.

 

[tim.rose2]

Thanks for the info Maj.
Sounds like it's best left until the spring if the entrance needs clearing and streams redirecting.  We won't have time this coming Sunday as I've a deadline to get home.
For future reference, is Hobnail fitted with the new or old CSCC keys?
Will go with plan B this weekend.
Cheers
Tim