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CHANTOIR DES FAGNOULES
One of the most exciting Belgian explorations of the past years...


 

The dig and the discoveryThe only way on was this narrow fissure!
In the Spring of 2002 we started digging in this interesting sinkhole near Awagne (Dinant).  The entrance was totally blocked by debris and mud, but after a couple of days of work, we had cleared this and we could see a very narrow (only 10 centimetres wide) fissure that exhaled a fresh breeze of air.   Because the average Avalon-caver doesn’t stop for this kind of “small problem” we soon attacked with all heavy stuff we dispose off. The fissure was progressively made wide enough (50 cm). However after having progressed 3 metres horizontally, the fissure, still only 10 cm wide, became vertical.  Despite this complication we continued and turned the narrow crack into an artificial  pity of 4 metres deep.  Only 5 weekends later, we made a break-through into a chamber.  Big piles of unstable boulders were carefully avoided and that same day, we discovered a big new cave. Highlights were a big room and an active streamway.   This river was most surprising: it was a real “collector” (main drain) despite the fact that we were only at a depth of -30 m.

Click here for a “live” report of the big breakthrough on April 13th, 2002 (in Dutch)

The next day, another team continued the exploration.  Downstream they were soon stopped by a sump. But upstream, the cave offered them a lot of caving pleasure. They explored a few hundreds of metres of galleries, mostly active (with a pretty river) and they found a second big room in which a new and deep sump could be seen.  

In only two days time, we explored +/- 500 m. of galleries.  

Click here for a “live” report of the big breakthrough on April 28th, 2002 (in Dutch)

In the following months we dug at many other places in the cave, without however discovering “the” big continuation.  We surveyed the cave entirely  and reached nearly 800 metres of total length which is not bad at all for a Belgian cave.  But it became clear that the only way on was through the sumps.  The cave was still 3 km away from the supposed resurgence and 135m higher.  We performed a fluoresceine dye test and proved the relation between the cave and the resurgence.

May 2002: the first dive
Our friend Lucienne Golenvaux, the most famous Belgian female cave diver ever, dived the final sump in May 2002.  The expectations were low, because the sump was very narrow and we had tried in vain (even with a mini underwater video camera) to penetrate it.  But, Lucienne disappeared into the muddy water without any hesitation and stayed away for quite a while.   But when she re-surfaced, we could see the disappointment in her eyes.  At first it went well, the sump was narrow, but not too narrow and descended regularly keeping the same section. Then, after 7 metres, she hit an obstacle which she believed to be a pile of boulders. Yet the roof of the sump went up again, however she could not get through.  That day,  Lucienne also dived in another (upstream) sump, but there she was also stopped by a passage that was much too narrow.  

Peter lays down in the sump, drilling holes with the Bosch drillAvalon tries to shunt the final sump
Since the sump wasn’t diveable at all, our only option was a serious attempt to “eliminate” it. During many weekends we worked in the sump. This was very difficult work, we had to lay down in the deep water, with a heavy 220 volt hammer drill in our hands. After a while we already realized that we had started something that would take many months of work, without any guarantee for success. After all we didn’t even known the real length of the sump!  We considered other possibilities, such as pumping the sump dry.  But the depth of the cave (-35m) and the regular and high flow rate of the river (8 litres/second) made this undertaking also quite impossible.  So, the only thing that we could think of, was to have a diver investigate the other sumps in the cave…

December 2002: second dive, upstream
Michel Pauwels dived in the most upstream sump, situated in “Salle Goelasnuf”.  It is a double sump, in two parallel rifts (about 70 cm wide and 4 m long).  Michel went down 3,3 metres where the passage become horizontal.  Unfortunately it was too low to continue.

That same day, Michel took a look at the downstream sump in which we were still working.  He felt that a “second opinion” was necessary and expressed the desire to dive again this sump, in which Lucienne had failed to find the way on.

June 2003: third dive... sensation: the downstream sump is passed!
Coup de théatre:” exactly one year after Lucienne Golenvaux, Michel dives in the narrow sump. After 7 metres he meets the same restriction that had stopped her. But after having cleared some mud and gravel, and after three (!) attempts, he manages to pass a technically difficult narrow slot. Five metres further he surfaces on the other side of the sump, and meets a second shorter sump that he also passes!   A bigger gallery (two by two metres) goes on, in which he walks for about 30 metres. The gallery continues, but Michel prefers to come back later for a detailed exploration.   Everybody is very happy, and even if we, non-divers, might never see what’s behind the sump, we sincerely hope that next time Michel will explore many hundreds of metres of new cave passage.

Click here for a “live” report of this sensational dive on June 29th, 2003 (in Dutch)

Michel and Jacques are preparing themselves for the dive.November 2003: fourth dive... a big continuation is found
During several months we are dreaming of those virgin galleries behind the sump.  Could there be a big streamway, continuing over more then 2 kilometres towards the resurgence?  But we know that we should better not expect too much, too soon.  It is more likely that a new sump will quickly block the way onwards.

Finally comes Sunday 30/11.  An Avalon-team, assisted by Lucienne Golenvaux , carries 8 kitbags of equipment to the sump. This time Michel Pauwels will not dive alone, he has brought his friend Jacques Petit who is also an expert when it comes to dive in narrow sumps.  They both have two 6 litre bottles. Michel first dives the sump alone, and puts a solid rope through it. For 15 minutes we can hear him hammering a spit into the rock (the sound is being transmitted through the rock), then he fixes the rope and returns.  Meanwhile Jacques has prepared all of his gear as well and with a 10 minute interval they both disappear into the sump. Michel goes head first this time, but not without difficulties. The entrance of the sumps is narrow and it takes at least two minutes before his legs and boots finally disappear under water!   Ten minutes later; bubbles stop arriving at our side of the sump: they must both be through.   For us a long wait starts, we keep busy and warm with some digging work in another part of the cave.  When we have finished this, we return to the sump: still nobody.  So we just sit and chat (quite easy with Lucienne in the party!).

 

Michel just before the diveTwo and a half hours later, we suddenly hear bubbles again.  Soon we see the familiar yellow glow of halogen torches in muddy water, and then Jacques surfaces.  He is really excited and all smiling, and tells us what they have found.  A third sump, which they could by-pass by another gallery. A few inlets too, but the most exciting discovery was a big fossil gallery, sometimes up to 10 metres wide, with decorations, helectites and gour pools.  Through deep holes in the floor they could see the river. Finally the gallery was blocked by a boulder collapse, but they were able to descent between the boulders and to reach a lower level. There a spectacular 8 metre high waterfall crashes down, it is probably the main river again.   The water disappears a bit further in a fourth sump. A narrow one, but nevertheless it will be one of their objectives when they come to dive again (within two weeks).   They estimate to have explored about 200 metres in length. Several possibilities and climbs remain unexplored.

Michel arrives half an hour later, he has surveyed the two sumps, quite difficult with zero visibility. He also tells us that he has made many photos while exploring behind the sump, so within a couple of weeks I hope to post a few of them here on the website.

Anyway, we are very happy with the results, and so are the two divers. The caves reaches +/- 1000 metres in length now.   But for us, non-divers,  we can only dream of the cave behind the sump, and hope that one day we’ll find a way to get there.  Other sinkholes are known downstream, but all situated in a private forest. We hope to start negotiating on with the owner soon.  

December 2003: fifth dive... survey job
One of the divers had a serious cold and so they decided not to continue the exploration behind the sump.  Nevertheless, Michel did dive, just to do a few hours of surveywork of the gallery that comes immediately after the sump.  Important survey work for us, because we are working on a "cunning" plan (like Baldrick?) that will - if all works out well - permit us to pass the sump... dry!   No big demolition works this time... just some pure hydraulics.

16 February 2004: 7 Avalon members go through the sump... dry!

Today we finally passed the sump!  The whole gang (7 people strong!) went through in groups of 2 to take a quick look of the new part that had been discovered by cave-divers Jacques en Michel a few months ago.
It was fantastic. It is really so big, one would say a "French cave": rooms up to 10 metres wide, interconnected by big galleries of 3 to 4 metres wide.  And it goes on and on and on, over several hundreds of metres in a nearly straight line.  Some nice formations and beautiful virgin mud floors can be admired on the way.  The biggest thrill is the 6 meter high waterfall, that can be reached by going down a fantastic fossil phreatic tube (2 metres in diameter). You can hear the waterfall roar over a long distance, as it tumbles down in a big and deep pool of water. Finally the river disappears into a black sump.

Paul werkt aan de dam waar de rivier wordt gecapteerdAnyway, the diver's estimation of 200 m  in total length is way underestimated, I would say there is at least 500 m!  Time being, we will suspend further explorations until the dry season. We have proven our point.

And so, HOW did we do it, going dry though a 20 metre long DOWNSTREAM sump in which +/- 50 cubic metres of water per hour flows in?  Pumping the sump dry was impossible, because a) downstream sump b) narrow sump and c) too much water.  A deadly combination. 

In very short: the river has been dammed upstream (see photo right) and is then diverted into a flexible tube of 15 cm of diameter. The tube runs for 110 metres in length (!) and even passes the 20 metre long sump (thank you, dear divers!) and finally ends way behind the sump.  Since the river no longer flows through the sump itself, but through the tube, all we have to do is pump the water out of the sump and go through it! 

De sifon bijna leeggepompt! Foto: Mark MichielsThe photo left shows the sump and the big red tube in which the river flows (15 litres/second).  The grey tubes are used for pumping the sump dry.  Simple comme bonjour.  And exciting too, isn't it?

But, this project that started as a crazy idea of mine, has occupied our club for many, many weekends now, and believe me: Avalon at full speed, is like a locomotive running on nitro-methane. We have dragged and carried hundreds of kilos of equipment into the cave, we have invented and tried out one solution after the other in order to cope with the many technical problems that we met.  But we did it!  And as promised, you will find very soon on these pages a more detailed description of our unique project.

 

May 2004: a new sump passed and many new discoveries made

Fossil gallery in the Réseau J&M During the weekend of 8 and 9 May, we planned to pump dry the "Ex-Terminal" sump again, in order to assist the divers in their attempt to dive the new downstream sump at the end of  "Réseau Jacques & Michel".  But Saturday, the river was in flood and both divers had to go on without us. Yet their expedition was successful, because Michel managed to dive that new and narrow sump? He surfaced after 10 meters, had to follow a low "duck" ("voûte-mouillante") for as much as 20 m., and then walked for about 30 m. in the river again. Then he was stopped by... yes it's getting boring... a new sump.  This sump looks very diveable. So, a success, 60 m of progression and good perspectives.

Sunday it was a lot dryer so we managed to pump the sump. Behind it, we started surveying and totalled several hundreds of meters of survey, which is only a fraction of what is really there to survey and to explore still. Meanwhile, I made a lot of pictures so everyone can see for himself what it is all about.  The waterfall in Réseau J&M

A few weeks later, 20/21/23 May, we went there for three days in a row. Dry weather, so we "pumped the sump" again. Exciting and exhausting work it was. Once empty, the sump refills and the passage is closed off again after only 15 minutes, because of a water inlet somewhere in the sump itself.  On one moment, the pump broke down for half an hour, while 3 of our members where behind the sump!
But we surveyed again, and we also discovered at least 100 m of new passages. The most beautiful part was a long and spectacular river part, in fact the active lower level which ends at the top of the waterfall. Beautiful passage!   The streamway in Réseau J&M

After this long weekend, the survey figure of the cave has reached the 1100 m mark. But there remains at least another 400 m to survey, so we can safely assume that the cave totals 1,5 km in length.   So we can add the Fagnoules to our list of "major" discoveries. And it isn't finished yet there, believe me!  At the end of the cave, we are now at -55 m while the resurgence is at  -135m!

 

Stay tuned, for more hot news about one of the most exciting explorations of the moment.  

Incomplete Survey ( screenprint)

 

 

 
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