Andy Smith
MIne-action specialist

Comment: What are the IMAS handtool requirements?

 

I was recently asked to respond to the above inquiry, which came from a serving soldier and made particular reference to "prodders". My response is reproduced below.

1) IMAS and prodders

The only place that hand-tools are mentioned in the latest IMAS is in the revised IMAS 10.30 SOH PPE, where it says:

"Hand tools should be constructed in such a way that their separation or fragmentation resulting from the detonation of an AP blast-mine incident is reduced to a minimum.  Hand tools should be designed to be used at a low angle to the ground and should provide adequate stand-off from an anticipated point of detonation."

The IMAS requirement for compliance is weighted using the terms "shall" and "should". When "shall" is used, all IMAS compliant demining groups must do what is written. When "should" is written, IMAS compliant demining groups should do what is recommended unless they have a good reason not to. This weighting means that demining groups do not have to take note of the advice about blast-resistant hand-tools, and many do not.

2) The use of "prodders" in demining

Many humanitarian demining groups do not use a prodder at all. The remainder use the prodder as a tool to loosen the ground prior to excavation - when investigating a metal-detector signal. The tools are used to expose the side of a mine safely. See: http://www.nolandmines.com/investigatereading.htm for how this should be conducted.

As far as I am aware, no professional deminers clear ground using prodding as a clearance technique (some include it as an emergency method to use when checking the ground around a victim who must be rapidly extracted from a hazardous area). It is not widely used because it is impossible to prod to the required depth (even in sand). See Statistical Analysis and Experiments in Manual Demining, J.Trevelyan, UWA. 2003  http://www.mech.uwa.edu.au/jpt/demining/reports/Trevelyan%20EUDEM-SCOT2003%20030618.pdf

A second reason is that prodding is the least safe method of searching ground available. A comparative study of demining methods that assessed relative speed, safety to deminers, and thoroughness of clearance was conducted in 2004 and is in the GICHD publication "A study of Manual Mine Clearance". The study found that the method most likely to initiate or leave mines behind was prodding - by a very wide margin. This confirmed what many in the field already considered obvious.

3) The design of prodder you want to buy

You are considering buying a prodder that breaks down to go into a pouch. This does not meet the IMAS recommendation because it will separate in a blast event. The material used should be hard enough for prolonged use while being sufficiently malleable to distort in an AP blast event. It must not break up - because if it does it may turn a blast event into a fragmentation hazard. Even hard plastic shards from a handle have penetrated deminer's chests in accidents with inappropriate tools. For this reason, the blade must extend through the handle, and the handle should be shock resistant, not hard plastic. For the blade, titanium and high carbon steels are not suitable because they do not distort in a blast. They either shatter or transfer the energy direct into the user's hand: both of which are undesirable. Cheap E304 (low-grade) stainless steel has a long life and bends in a 240g TNT blast event, remaining in one piece. I do not know the grade of stainless steel used in the prodder you want to buy, but I do know that it is likely to break at the threaded join and at the handle in a large AP blast mine event. It should be tested several times with its point at 30 degrees and in the middle of a PMN mine.

Basic geometry (triangulation) dictates the length of a prodder to reach a required depth at a 30 degree angle to the ground surface. 30cm is usually long enough. However, ground friction is such that (even in sand and loose soils) the usual clearance depth cannot be reliably reached by pushing a prodder into the ground and "feeling" for obstructions. It can sometimes be achieved by using truly excessive force (hitting the handle with a hammer, for example) that allows no tactile feedback and so would apply unwitting pressure to any concealed mine in the way. Friction is such that meaningful tactile feedback from the prodder is minimal in most soils at depths of more than 3 cm. In soils with any moisture content, ground friction can be reduced by using an MIT profile blade that is twisted after insertion. The narrower the prodder blade, the less the surface area and so the lower the friction. But a blade still has to be strong enough not to bend readily.

Generally, the longer the tool, the easier it is for a kneeling deminer to use it at a low angle to the ground. A 30 degree angle does not guarantee that the pressure plate will not be prodded onto. When AP mines have a large pressure plate (the PMN for example) prodding onto it is likely even when investigating a known metal-detector signal. The most common accident in Humanitarian Demining is the initiation of a PMN that has been "detected" and is being exposed with hand-tools.

4)  Concluding recommendation

Prodding does not give confidence of clearance and is an unsafe activity. Training for prodding gives false confidence in the technique and may abrogate the employer's duty of care. If "emergency" clearance with a single hand-tool is required, the removal of the ground surface with a scraping tool is a better option. Properly applied, a scraping tool technique can approach the device from the side.