Cwm Dwr II - Echo Beach - Far Away in Time

We had had an encouraging days progress on the previous digging trip with a tantalising glimpse of open passage through the airspace above the partly drained sump.
We returned with a little more knowledge of the site, digging gear, a second fire hose, video gear, photo gear and a set of surveying equipment all in anticipation of entering new or at least unsurveyed passage. We arrived on a fine Saturday morning and took a little persuading to break off tea drinking in the sunshine and head underground.
Faffing over we went underground taking in a second fire hose to halve the time it would take to drain the sump. With a little video taken on the way we were soon set up and spent an hour clearing out rubbish and old digging gear from the cave. With the sump open, we bailed the last bit of water with buckets and then spent and hour clearing out the bottom of the sump. Eventually with a "Mark" sized bit of passage we could stick our heads through and take a glimpse of the passage ahead. Keith went through first and reached a large pool at the top of the slope. He gingerley dug a trench to drain the water back to the sump pool, where we bucketed out the water as it filled up. With the top pool drained as much as he could he popped up through a hole in a calcite floor. He then excitedly called us up to have a look.

Setting up the syphon in Sand Sump

The passage above was larger and started with a sand beach and a booming echo. This soon gave way to a calcite floor. We took off muddy oversuits and headed along the passage until we saw some tape around a small nest of cave pearls at the end of the passage. It was clear that someone had been here before and we had a look at two low side passages. Both were pushed a few body lengths to get too tight for even Keith to make progress. We then decided to call it a day and return to the cottages for hot food a tea.

A section of passage at the end of Sand Sump

We were joined by Mark and Chloe for an evening meal and then on the Sunday we entered the cave with some hand tools, photo gear, video gear and survey kit. We found that the sump pool had not refilled overnight - and encouraging sign. Jess and Brendan undertook a survey of the passage while the others looked at the digging possibilities. After a few hours video had been taken, and idea of a digging strategy had been formulated and a survey had been undertaken to the end of the main passage until Brendan ran out of lead in his pencil. At this point everyone was quite cold and so we exited the cave taking out kit as we went.

Rough survey of the Sand Sump extensions

Caves of the Cwm Dwr Quarry - based on survey © South Wales Caving Club 2015

As we left the cave we did a clean-up operation removing old digging tools, rotting wood cables and fertiliser sacks to leave the cave litter and tool free apart from a small amount of current equipment at the sump.

Clear out of old digging gear after the weekend

Some history of digging in Cwm Dwr II - courtesy of Tony Donovan

In around 1990 Malcolm Herbert, Hywel Jopling and Owain Harvey siphoned the sump at the top of the sand slope in Cwm Dwr 2 and it takes between 3 and 4 hours to drain. Owain was small enough to get through the siphoned sump which was tight and beyond there is some leads heading up dip which he thought looked interesting which could be enlarged.
In 1994 Tony Donovan, Mike Booth, John Hale and Paul Roberts dug the trench in the floor with the intention of draining the sump completely which would allow digging without the need for siphoning the sump every trip, during one of the trips Paul Roberts from the Isca Caving Club wanted to have a look for himself as he was small enough to get through the tight bit in the siphoned sump being roughly the same size as Owain. On the first digging trip when the sump was siphoned John Hale was with Tony Donovan and he failed to get through the tight bit in the sump section, on the 2nd occasion Paul Roberts struggled and just got through and he looked at the leads, but detected no draught.

Present: Chloe Burney, Mark Burgess, Jess Burkey, Mark Burkey, Keith Edwards and Brendan Marris

Cwm Dwr II - The Wrong Dig

Regular rain showers had kept the Brickworks Dig topped up with water, and with only enough people available for one days digging we had sought out an alternative site to work on, as most of our time would be spent dealing with the water at the Brickworks. We chose an old site in Cwm Dwr II, and after arranging permissions with the OFD Management Committee and Natural Resources Wales we were able to give this location some attention. There had once been a short sump in the entrance series to this cave - Helen's Horror which had to be syphoned to gain access, but this was removed some time ago and now is no more than a short wet crawl.

We entered the cave and rigged the 10m pitch down into Default Chamber. It is here that a slope leads up to a 20m long sandy passage that leads to the Sand Sump. The sand had previously been dug and only a small access crawl led through to what was once a body sized sump which had now silted up somewhat.

Keith in the sandy passage that approaches the Sand Sump

A view of the sump at the start of the dig with bucket for scale

A close-up view of the sump at the start of the dig

To work the dig efficiently we removed the sand fill on the approach to the sump, clearing it from the sides and lowering the floor by 30-50cm. After a couple of hours and 40 buckets of spoil removed we had good access to the sump and we could now start draining it. Only a small part was visible of this perched reservoir, we expected to drain it fairly quickly, bailing it with buckets. After 100 buckets of water had been removed and the water level only dropping a few inches we decided on a Plan B. Brendan went back up the ladder and to Helen's Horror where a long firehose that was once used to syphon off the water could be found. This 40 metre heavy duty hose was brought back to the pitch and then lowered so it could be used to syphon the sump. At first we attempted to start the syphon by sucking on the pipe, but this failed, so Mark headed back up the ladder, the bottom end of the hose hauled up and the 10m head of water was used to fill the hose. Once the hose was full of water, it was dropped to the floor of the chamber where it began to syphon off the water immediately. The flow of water was directed to join the stream and then we returned to the sump. At this point most people went off to explore the cave while Mark and Brendan returned to the sump to monitor progress. It became clear that there was a large volume of water in the passage beyond as the water level very slowly fell. Rather than wait we continued to drop the floor of the approach to the sump. With everyone back at the dig over the next three hours we were able to clear about 40cm depth of sediment from the bottom of the passage over a 4 metre length, following the water as it slowly receded, until after three hours an airspace appeared. A short while later the hose broke the surface of the water and the syphon stopped. The passage is still too silted up to get through at the lowest point. At this point we had removed a further 60 buckets of spoil and were all exhausted and cold and so after all having a look through the airspace to the passage beyond we headed out of the cave knowing that on our next visit we would be in some interesting territory.

Keith at the sump at the end of the days dig

On our next visit we plan to set up the syphon again and drain as much water from the sump as possible. We will continue to remove the infill from the bottom of the sump to give easy access to the passage beyond, where we will be able to assess the future possibilities.

More information on Cwm Dwr II on this link.

Present: Mark Burkey, Keith Edwards, Chloe Burney, Mark Burgess, Ian Millward and Brendan Marris

The Extraordinary League of Gentlemen Cavers

Motivation was low on Sunday morning so after a marathon faffing and procrastination session we decided to visit some of the smaller caves in the vicinity of SWCC. We first went to assess the water levels in the Brickwork's Dig as we had planned a Club dig for the following weekend. We were surprised to find the water level above the cross rift, which would mean it would take a long time to empty the dig and be able to start work. We then headed off to look for a suitable alternative.

Cwm Dwr II

We headed into the Cwm Dwr Quarry to look at Cwm Dwr II a cave that was once difficult to visit as a short sump not far from the entrance had to be emptied to allow visits. About three years ago the sump was removed and so we were able to get in with little more than a crawl through shallow water. We arrived at the pitch into Default Chamber and rigged the 10m ladder and descended the 11m pitch. We looked at a sandy dig at the top of the chamber before heading downstream over long traversing sections to reach the sump. On our way out we went upstream and followed Ping Pong Passage to reach the choke that marks the end of the cave.

Twll Gwynt Oer

We were encouraged by Ian and Peter at the SWCC to go and have a look at Twll Gwynt Oer, a cave dug by Jopo that intersected a streamway that later feeds Cwm Dwr II. We lifted the covers off the cave and dropped down the 3m deep section of lined shaft to reach a concrete plinth. We then dropped through the hatch to reach the top of an 8m deep shaft which we rigged with a ladder to assist the climb down. At the bottom we first headed downstream to eventually reach the sump before retracing our steps and headed upstream to reach a choke with calcite formations. We then made our way out taking photos as we went.

Brendan in Twll Gwynt Oer - Photo Mark Burkey

Brendan in Twll Gwynt Oer - Photo Mark Burkey

Mark in Twll Gwynt Oer - Photo Brendan Marris

Ogof Y Dynion - Gent's Dig

We then walked across to Gents Dig - Ogof Dynion, passing the site of Zach's Dig as we went. The entrance to Zach's Dig has now been filled over as it was connected with Gent's Dig in 2006. After some trouble with the lock on the entrance to Gent's, we lifted the lid and descended the large concrete lined shaft to enter the cave. At the bottom a railway line led off, tempting us to follow, but it came to an abrupt end just around a corner. We then headed down a small descending passage just below the entrance which passed round a tight corner to emerge at the top of a short free climb with handline in-situ. We were now greeted with clean washed rock in the bottom of a wet weather inlet and overlooking a 6m pitch down into large passage below. We rigged the ladder and lifeline before descending and exploring the passages in the lower level. After exploring all the passages, apart from a tight awkward section that leads and connects to the passages of Zach's Dig we then returned taking some photos as we went.

Mark in Ogof Y Dynion - Gent's Dig - Photo Brendan Marris

Mark in Ogof Y Dynion - Gent's Dig - Photo Brendan Marris

Brendan in Ogof Y Dynion - Gent's Dig - Photo Mark Burkey

We emerged after 6pm to find the South Wales Caving Club deserted.

Present: Mark Burkey and Brendan Marris

Cwm Dwr Two - A Caving Spectacle

Having arrived at South Wales Caving Club for our dig weekend, only to find that the week's rain had completely filled the Brickworks Dig, we had to hastily change our plans. Splitting into two groups, one party set off to OFD II, while the second party decided to use the pumping equipment we had brought for the dig to open the sump into Cwm Dwr Two. Despite it's close proximity to the South Wales Caving Club, Cwm Dwr Two is a rarely visited cave. We set up the generator on the surface in the quarry and ran cable down to the sump and installed one of our pumps, connecting it to the in-situ rubber hose that runs from the sump to drop down the pitch beyond. The roof of the sump has been modified, so a minute airspace exists, and as we lay in the water connecting the pump you could feel the enticing draught from the cave beyond. After setting up the pumping gear we returned to the surface to collect camera equipment to photograph the passages up to the sump while it was draining. Due to the weather the sump was filling at a rate very close to what we could pump it out, so it took nearly an hour to drain it. Back on the surface to pack away the gear before heading into the cave, Brendan trod on Keith's glasses that were resting on the concrete plinth by the side of the entrance. After donning the specs for comedy effect Keith then managed to twist back the Poundland specials back into something resembling their previous state.

Steve Wallis in the chamber at the bottom of the fixed entrance ladder.

Steve Wallis in entrance series to the cave.

Steve Wallis in the crawl that leads to the first sump.

Crawling through the drained sump we headed to a junction where we met a stream coming in from the right and then proceeded to head downstream to the left where we soon arrived at the head of the pitch. A single ladder took us to the bottom of Default Chamber, where we had a quick look a sump and a dig at the top of the chamber to the right. The way on was then to follow the stream passage ducking under the spray of the water coming down the pitch as we entered the meandering Maine Streamway. The passage started as a walk, with odd climbs up and down to progress before the passage became more rift like, and progress was then by traversing and following the tube in the top of the passage. When we arrived at the last section of streamway we could again drop into the stream where it was followed until the roof gradually dropped in height towards water level as we met the downstream sump.

Derek Robertson traversing in the roof of the rift passage.

Derek Robertson in the lower stream passage.

Steve Wallis in lower stream passage.

See more Cwm Dwr Two photos here

The Video

Present: Steve Wallis, Keith Edwards, Derek Robertson and Brendan Marris