Cwm Dwr II - Sand Sump Extensions

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