Hunters Hole: problems with anchors

[Canda@CSCC]

I've cut and pasted this as it has relevance to anyone planning a visit to Hunters Hole (presently not-do-able).

PROBLEMS WITH ECO-HANGERS (P-BOLTS) ON MENDIP

UPDATE: Sun 8 April

Since the initial report of a problem with one of the Eco-anchors on the first pitch in Rhino Rift on 26 March a good deal of work has taken place. A team has already inspected the failed anchor, and the others. This inspection revealed a number of issues which are now being followed up. In due course attempts will be made to extract the failed anchor - together with some of its surrounding rock - in order to facilitate a detailed inspection of the failed anchor / resin / rock combination. In the meantime the Charterhouse Caving Company (CCC) is carefully controlling access to Rhino Rift.

The investigation team also reviewed the available installation records for CSCC Eco-anchors. As a consequence of that review, and guided by some of the preliminary findings from Rhino Rift, axial pull tests were subsequently conducted in Hunters Hole. Of the 21 anchors present there, 16 were tested (5 are located in positions where the puller cannot be fitted to the anchor). Of those 16 anchors, 8 passed the axial pull test (meaning that they withstood a force of 6 kN for 15 seconds), but 8 failed the test, though it must be emphasised that whilst anchors did move under initial loading, NONE came out of the resin. The defective anchors have been tagged and notices placed in the cave. Under the circumstances the untested anchors must, of course, be treated with suspicion. The land owner was informed of the results and advised that cavers should not use use Hunters Hole until the problem has been resolved. The CSCC fully support this decision and would ask cavers to abide by it.

The installation records also indicated a common factor with Eco-anchors placed at several other locations which, due to a lack of time and manpower (it being the Easter holidays), have not yet been tested. These locations are: the Cowsh Avens in Swildons, the Ladder Dig Extension in GB Cave, and Split Rock Quarry.

Until the Eco-anchors at these locations can be tested, cavers are also asked to either keep away or to use CAREFULLY-SELECTED alternative belays. The CSCC has put a notice and new lock (key available locally if needed) on Priddy Green Sink to deter through-trips and requests that cavers do not climb up into Cowsh Avens from Swildons 4 and then use the untested anchors to return to the streamway. The CCC will place their own controls on GB Cave.

The CSCC, together with the BCA Equipment & Techniques Committee, are now considering what other testing and investigations are required. However, given that there are some 125 Eco-anchors placed under the national scheme on Mendip, this will clearly take some time to complete.

The Chairman and some members of BCA's Equipment Committee have been fully informed and involved in this issue and support CSCC's approach.

It is worth noting that similar axial pull tests have been conducted in both Derbyshire and Yorkshire without a single anchor failing the test. In Derbyshire alone, this amounts to over 215 anchors as at late 2006. So far the problem seems to be confined to Mendip, though the reasons for this have yet to be isolated and demonstrated to a reasonable standard of proof. Further work is planned to be conducted across the whole of Mendip in response to these events.

Regrettably there is a national shortage of Eco-anchors and the manufacturer's have stated that they will not produce any more! Some of the few anchors which remain may be required for testing hypotheses to explain the cause of these failures. The Equipment Committee was already working on a programme to select a suitable replacement. That work continues, but is unlikely to be completed before late Summer or possibly later if the investigation on Mendip takes any length of time. Thus the failed anchors may not be replaced for quite some while. The BCA and the CSCC understand the frustration this will cause.

The Equipment Committee is planning to hold a meeting either in late April or May to discuss the results of the findings and what else should be done, including possible reassurance work in other regions.

Further updates will be posted on the BCA and CSCC websites, and notified via the CSCC email list.

S King A Pryke
CSCC Secretary BCA Equipment Committee Chairman