Originally, as part of the National Caving Association (NCA) Anchor Instalment Programme, DCA has been placing resin bonded anchors in Derbyshire caves and mines since 1991. On the demise of NCA the newly formed British Caving Association (BCA) continued this work through its Equipment Sub-Committee. The anchor selected by both sub-committees for this programme was the DMM Eco anchor.
These anchors were specifically placed on trade routes throughout the most popular venues to facilitate safe free-hangs for SRT techniques and ladder and lifeline.
Unfortunately in 2005 DMM stopped production of these anchors which left the Equipment Sub-Committee with a project to find a replacement. After much work a substitute anchor, the BP, was approved which exhibits an increased axial failure load of between 34 - 64kN (approx.3.4 - 6.4 tonnes), dependent on the limestone substrate. These anchors will be used in placements from August 2012 onwards.
In 2008 DCA initiated a programme of Eco anchor testing in situ to ascertain if time and underground conditions had contributed to a reduction in strength. Of 400+ anchors tested not one failed a 10kN (approx 1 tonne) axial load.
In an effort to control anchor placement by unqualified installers, and in line with DCA policy, all installations must be ratified by a General Meeting of the Association and carried out by persons who have successfully completed a BCA training programme.
Installers are re-validated every three years under the terms of the Equipment Sub-Committee document Installation Procedure, Training & Documentation (IPTD) to maintain competence and to ensure compliance with procedural updates. All anchors placed under the above programme are covered by BCA 3rd Party Liability Insurance.
Whilst DCA has made every effort to ensure correct and safe installation it is the responsibility of cavers using these anchors to check that they are in a safe condition.
The following checks should be carried out on all anchors :-
- Rotational movement of the anchor either caused by resin/substrate or anchor/resin failure. Check by twisting using fingers and thumb. Flexing of the resin +/- 1mm is acceptable.
- Any egress of the anchor from the hole.
- Wear grooves or abrasions to the internal structure of the anchor eye. A reduction of more than 1mm in the 8mm diameter bar is not acceptable.
- Any mechanical damage caused by rock fall or improper use.
- Fracturing of the rock within 20cm of the placement.
If defective anchors are identified contact Bob Dearman (equipment @thedca.org.uk) with the following details :-
- Name of cave/mine.
- Pitch No.
- Position of anchor in the series.
- Details of Y hang, traverse position or deviation
It is essential that on pull-through trips ropes are not placed directly through the eye of an anchor. Over a period of time this causes abrasion damage to the internal radius of the eye and eventually the need for replacement. From an effort and conservation point of view this is undesirable. Always sacrifice a maillon rapide or other connector.
On regularly used pull-throughs DCA has fitted wire Y hangs with a large diameter pull through ring. This ring is able to rotate to negate any point abrasion. An example of this type of assembly is at the end of the Upper Series in Giants Hole to allow descent back into the Crabwalk. There are others in Giants Hole, Oxlow Caverns and Nickergrove Mine.
Details of anchor placements can be found in the DCA Handbook (Rigging Guide section) and the Rigging Cards published by Crewe CPC.