Recent Sump Draining Operations in Ogof Igam Ogam

Ogof Igam Ogam, a cave in the Little Neath River Valley near White Lady Cave, was discovered and explored in the Spring of 1989 by the Club (see Pelobates No 55). Because of the three sumps, near entry to the cave had only been achieved by divers or when the sumps were pumped out as they were in the Summer of 1988. This fact has been rather frustrating as the cave leads towards an area between the resurgences in the Little Neath Valley and Pant Mawr Pot where there is thought to be the possibility of large cave systems.

Of particular interest is the fact that the main passage is draining up dip in the opposite direction to the river, only some 200 feet away. I and a number of members had been keen to get in and explore leads without the need for diving operations (which in this case are hazardous).

The 1988 'dry' entry had been achieved by using a submersible pump to pump water through the perched sumps. This had, however, involved a diver taking the pumps through the sumps and cost a substantial amount in hired equipment. Having been involved with sump syphoning operations with Colin Bunce and Brian Judd down Poll na gCeim in Clare a couple of years ago, I spent the winter scrounging lengths of tubing and fittings with the idea of draining the sumps by syphonage.

At the end of May 1989, the weather looking good and enough pipe being available, along with a ship's bilge pump, operations commenced with the pipes for sumps one and two being dragged through the sumps by diver Malcolm Stewart. The next day the bilge pump was taken in and connected to the pipe in S1 (about 40 feet long). After some vigorous pumping the syphon started and was left in the deepest accessible part of the passage.

The following day on a solo trip into the cave the level had dropped by about four feet and revealed the top of dreaded S1 pot. The syphon was restarted and assisted by hand pumping. The trip was shorter than anticipated because of strange booming noises in the cave. Was it the sump breaking? The commencement of nuclear war? Practice bombing on Pant Mawr? The eventual realisation was that it was a vigorous thunder storm. Vigorous would also be a good way to describe my exit from the cave. The following day was spent reconstructing the knee and elbow pads on my wet suit and wishing that my body could be repaired as rapidly. Fortunately the next day did not threaten thunder so myself (less elbows) and Steve Wray, Paul Stacey and others descended to review progress. Unfortunately syphonage had stopped about five feet from the break point and so hand pumping commenced. After about an hour we noticed very heavy breathing from some members of the party due to carbon dioxide build-up and although we continued for as long as possible we evacuated the cave without breaking the sump. We emerged despondent after spending three hours up to our necks in almost freezing water breathing foul air, and it was with some difficulty that the following day people shunned the beautiful Bank Holiday sunshine to face the wretched entrance grovel again.

The failure to completely syphon or pump the sump resulted in a somewhat desperate solution and it was now planned to bail the pot into a higher level pool from which the syphon would still work. This proved successful and S1 was quickly passed, though initially the trip was delayed while we explained the purpose of two large coal scuttles and a bag of concrete to perplexed Little Neath cavers.

The pump was then moved through to S2. Unfortunately the end of the pipe was under water and could not be reached and had to be retrieved by Malcolm Stewart in a heroic midnight solo trip. However, once the syphon started the sump drained within several hours with no problems. S3 was initially free-dived and syphoned from the other side and the cave was again open.

The following weekend I returned with Adrian Paniwynk and Martyn Pickering and it was fortunate that not a lot of water had entered during the week which meant that S1 only required a little bailing. After concreting the pipes in at the sump lips so that they would self-start we headed for a prod at the 'Snorers Annexe'. We were rewarded within half an hour with a drafting rift with continuing passage visible 10 feet down. Eventually this was forced by Adrian Paniwynk to about 30 feet of new passage which we believe is now on the other side of the River Neath. While digging in 'Snorers Annexe' a climb up through horrendous looking boulders had been noticed. At the top of this a lot of river debris, including fresh drinks cans, was noted indicating an alternative entrance. However, radio location shows that this point is under a lot of rock, but a small tube is being dug from the river bank towards the spot and is now about 30 feet away.

Another weekend saw an assault on S4 and nearly the end of this article when the author became tangled with a diving line while free-diving S3. A large dam was constructed using fertiliser bags and the water bailed into it which resulted in a further 30 feet of cave. Eventually the dam burst. This particular activity was repeated a few weeks later with exactly similar results, except that we just missed flushing a diver through the sump. This weekend ended on a somewhat dramatic note when a local farmer telephoned a number of well-known caving personalities, saying he was going to blow the whole area up because someone hadn't paid him 40p.

In the Spring of 1990 efforts to get to S4 restarted and after a number of trips we eventually passed S1 only to find the pipe in S2 blocked with crud. Initial attempts failed, but I acquired a small air bottle containing 192 ATS of air. I thought this would shift it, but it didn't. However, with the valve fully open into the pipe and the gauge reading 72 ATS, the stem valve overpressure whistle lifted and caused considerable panic. Fortunately, sucking on the pipe released the blockage and we drained the sumps. However, all our efforts were wasted as the river flooded during the week and everything filled up.

As a result of the 1989 efforts we realised that the syphoning systems would have to be improved and we have now added another 100 feet to the system taking the pipes from S1 and S2 through S3. This means that the S1 pot will now syphon dry. During Easter 1991 we drained the sumps in four trips and on an expedition to S4 rebuilt the dam with a three bag base and a sheet of polythene and are planning an assault on S4 in early May.

Note: You are quite welcome to go down Igam Ogam. However, please contact me or Adrian before you do so that we can advise you on procedures and especially on where to leave pipes and equipment so that we can restart the syphons.

Chris Crowley