On the 18th of March 2016 the majority of the anchors in Rhiwbach mine were inspected and tested. This work was requested and funded by Go Below Underground Adventures Ltd who engaged Pete Knight to undertake the testing.
The anchors were tested to 6kN for 15 seconds using a Hilti HAT-28 anchor tester with a current calibration certificate. All anchors that passed (showed no movement, deformation or rock failure) were marked with a green cable tie. Anchors that were deemed to have failed (moved, deformed or detached from the rock) and could not be removed from the mine were marked with several red cable ties. No failed anchors remain attached to fixed rigging. Unmarked anchors were installed after the 18th March and remain untested.
There are no plans to retest any anchors on a regular basis as it is a concern that the resin bond may be damaged by regular high load testing. No Petzl P38 Longlife anchors were tested in Rhiwbach.
Tyrolean Area
All anchors were tested in this area. One Petzl Collinox anchor was removed from the wall under the test load. It detached with a section of slate that showed a hidden area of quartz weakness. This anchor was not replaced as it was immediately adjacent to another which passed the test.
Pool Traverse in next chamber
The final anchor in the chain appeared to have been hammered into the rock to prevent use. It could not be tested or removed but was tagged as a failure. All remaining anchors passed.
Climb and Traverse to Abseils
All anchors passed.
Waterfall Climb
The lowest of the Collinox anchors had a small amount of spalling under test. It was tested to 10kN as a precaution and passed. This anchor should be checked regularly by users to identify any further rock degradation.
Airshaft
3 Collinox anchors failed in this section of the mine. One was removed completely but the other 2 are awaiting removal/destruction but have been tagged as failures and removed from the rigging.
1 Collinox was removed from the rock along with its resin. The hole appeared to have not been cleaned prior to installation. A second Collinox was removed because the section of rock it was in split apart. The third anchor was another Collinox, which began extracting with its resin. Replacement anchors have been installed already but will not have been tested.
Summary
The testing does not diminish or remove the important requirement for all users to inspect the anchor and overall safety system on each and every use. The nature of the rock and the type of use these anchors receive may mean that an anchor can become suspect or even fail in the future. This can happen without warning and cannot be predicted by this testing. All fixed rigging attached to the tested anchors remains the responsibility of the installing organisation and all users are reminded to inspect for safety prior to each and every use.
Peter Knight 3/5/2016
