Incident Report

2024-04-2730/07/23 Two divers were digging a sediment bank to unblock a pipe. This part of the cave was not overhead, and the pipe was under three foot of sediment. Tools, an air lift and an air jet on a pole was tried. The air jet on a pole was particularly useful at loosening the sediment. The vis was consistently ‘black out’ Diver one found he was unable to draw air from his second reg (Cyklon 2000 with a stocking filter), and on inspection he found it 95% full of very fine sediment. He showed diver two, who also found it amusing, the second stage was dismantled and washed out. All regulators were checked and had sediment build up to varying degrees, with one reg (no stocking filter) having a wet breathe due to a twig in the exhaust. An increase to the frequency of checks was implemented by both divers. 27&28/04/24 The diver was digging a fine sediment bank 100m into the sump at -6m. Because vis is always zero after a few seconds, the diver had three tanks, meaning that if/when the first tank ran out (used for penetration and working) they still had two tanks (two thirds) to exit. During the digging phase the diver checked the two spare regs. The Cyklon 2000 was tough to draw breathe. The diver gave it a good shake under water with no improvement, so headed out. At the surface the diver could still see some sediment, he tried to purge it under water which led to a free flow, he then washed it out with a good shake in the water. The next day the diver regularly washed out and checked his regs, and kept his regs pointing down, hopefully reducing sediment deposition. The diver noted a very ‘dusty’ feeling in his mouth when using his back up regs. On the surface he noticed sediment sticking to the filter, which may have been the cause. The diver postulates that the Cyklon 2000’s have more issues with sediment build up than more modern style regs, because of the ratio between the bore of the mouth piece and the internal volume.Test and wash out sediment from regs on a very regular basses when digging. Turning regs upside down may help reduce sediment deposition.