Rhiwbach Slate Mine, Cwm Penmachno, Betws-y-Coed, Conwy, SH 747471
2.4.16 & 3.4.16
DIVERS: Paul Marvin, John Carter
Support: Sue Marvin, Matthew Gration.
Recognising that this is a little'off brand' as its a mine dive, however it is reported here as no previous significant dives have been recorded at this site within the history of the CDG newsletter that the diver is aware of.
A series of exploratory dives were carried out in 2015 after being granted permits by CAL to see what existed in the lower flooded level. 200m of line was laid (cumulatively) from two separate dive bases. A rough survey was started and a far more accurate one is currently in progress by the divers concerned.
The dives that took place this year (April 2/3 2016) confirmed suspicions that the two separate dive bases connected underwater. Also, a number of artefacts were found and photographed. The state of preservation on some being excellent, but left untouched for future visitors and posterity. The flooded levels have now all been explored and are ongoing with permanent line being laid and connection to a further sump (now named 'no fins sump') likely. Diver noted presence of oil on the surface in a remote air bell. Max depth -15m (note: Dive Base 1 sump drops to -30m, but the way on at the discovered adit level is at -15m). Visibility circa 5m on the inward phase. Near zero in places on exit as the mine is very silty. A pair of 300 bar 7's used. A separate exploration dive was undertaken a day later with potential for a further significant connection.
A note concerning cylinder choice... A pair of 300 bar 7's are adequate for a worthy dive, although larger cylinders are an advantage. The main factor is the kit carry to the adit entrance. With some creative equipment packing, the walk to the adit entrance can be accomplished in two trips. Water temp requires a drysuit. However its worth pointing out that the walk is steep in places and covers a distance of approx 1.7km each way. The divers also wish to reiterate the dangers of diving in mines. A healthy fear of potential collapse coupled with some personal research of mining techniques goes a long way in prolonging ones life. Particular attention must be paid in large chambers (wet and dry!) where the roof span is considerable. All airbells must be viewed as toxic.
"I Dont Know Where I am Going, But When I Get There I will Know Where I am"