Andy Smith
Mine-action specialist
 


Risk assessments in the field


 


[While this document was adopted for use as a training aid with IND, the National MAC in Mozambique, it has been superseded by my paper on Field Risk Assessment (FRA) written in 2009 for inclusion in IMAS. Field risk assessments are now covered in detail in Generic SOP, Chapter 2: Safety.doc or Generic SOP, Chapter 2: Safety.pdf]

Assessing the risk involved in a certain activity has become an academic subject marrying mathematics to social science to determine probabilities. Like many of the new "sciences", risk-assessment disciplines allow the past to be used to predict the future - but with a very low degree of reliability. This is disturbing because field people often lack formal education and may trust academic predictions blindly, or they may reject them as unintelligible too readily.

Reflecting what is done in the field, my approach has been different. Rather than follow the strictures of the academics, my method of Risk Assessment is based on field observations, where risk is constantly assessed and reassessed, although the process is rarely recorded. The process is subjective, calling on all manner of field observations and experience - some of which may not even be conscious. I believe that it may be useful to make deminers aware of what they are doing so that they self-consciously bring in as many variables as possible and update their assessments at regular intervals - generally by a process of open discussion between those responsible for managing the risk and those who will take those risks.

The first Risk Assessment is made in order to plan the task. It dictates the tools to use, the process to deploy, the protection that should be worn, and sometimes the time of year when it would be most appropriate to work. As work progresses, new information may be acquired or a higher degree of confidence in some of the existing information may be reached. Both may require changes to be made in the Risk Assessment that will affect the methods and resources that are appropriate to use for the task.

For field deminers in Humanitarian Demining, the "Risk" that they are concerned to manage is twofold:

A) The risk of explosive injury to deminers while they work;

B) The risk of leaving explosive devices behind, and the consequent threat to civilians.

Professionalism and pride in their work requires that these risks are reduced to the lowest level possible at all times. Not all demining group managers give both concerns the same degree of importance. A few consider that demining is inherently dangerous and so consider that their "professionalism" must be judged in terms of the clear land that they hand back to the community, regardless of accidents/injuries to personnel. Others put the safety of their own personnel first, and accept that all "cleared" land retains a low level of residual risk for the end users. The best try to give both an equal importance.

While it is true that some explosive incidents are "unavoidable", in many cases the injuries resulting from these accidents could be avoided by using appropriate tools and protective equipment.

Similarly, while some residual risk always remains in a cleared area - especially when it has only been searched to a specified depth - it is in the interests of the field personnel for their own safety and professionalism to always aim to clear ALL explosive devices as they work.

The managers of many demining groups add a third "fear" to their list of "Risks". This is:

C) The risk of spending more money than is necessary to achieve the end result.

Sometimes, the pursuit of cost-effectiveness is in conflict with desires for safety and thorough clearance. In fact, if intelligent Risk Assessments are made from the start, some funders are amenable to cost-extension when the predicted risk can be shown to have been lower than reality. This is especially true when an effective National Mine Action Authority supports the increased Risk Assessment. And when a funder is unresponsive, the reputation of the group depends on them not allowing increased costs to lower their safety and clearance standards, so they should stop work until enough funds are available.

 

1. Threat assessment (explosive hazard)

Before starting any task, the explosive hazard in the area is assessed by reference to any Level 1 Survey, Technical survey and/or recce reports that are available. In some countries this advance work is reliable enough for the deminers to be confident that they know what explosive hzards to expect in advance. In others, the advance work is taken as a rough guide and the deminers do not expect to find out what explosive items are present with certainty until they start working. In all cases the threat assessment of the deminers is adjusted as they work, depending on what they find.

 

1.1 Typical mine threats in Southern Africa

These can be divided into:

Large AP pressure-operated blast mines
Small AP pressure-operated blast mines
Ground placed tripwire fragmentation mines
Stake mounted tripwire fragmentation mines
Bounding tripwire-operated fragmentation mines
AT mines (pressure operated)
AT mines (detonated with a smaller device)

The injury that can be expected from each mine differs quite dramatically. But the threat from each device is not assessed solely on the device type, also on a combination of its condition, initiation mechanism(s) and context.

Many mines that have been placed for a significant period are not in the condition they were in when they were placed. They may be more hazardous, or less so. An AP blast mine with a broken case is usually considered more hazardous and is often destroyed without moving it. If it has to be moved, it must first be "pulled" from a safe distance. This is usually intended to turn the device over, so increasing confidence that a small movement will not initiate it. Its subsequent transfer from one place to another should be undertaken with extreme caution. I recommend the use of remote handling devices that keep the deminer at least a metre from any blast mine during its movement. Remote "pick-up" devices that keep the deminer 1.5 metres from the device are commercially available.

The picture shows a two-handed device for picking up mines.

Many mines that are in good condition are routinely rendered "safe" for movement and later destruction. These include many AP blast mines and most AT blast mines.

The condition of some fragmentation mines may reduce the associated risk. For example, tripwire mines in areas where no tripwires remain intact are far less likely to be accidentally initiated than those where tripwires remain and are entangled in undergrowth. Stake mounted mines where the stakes have disintegrated along with the tripwire can be reliably inferred to have been in damp conditions that can render fuzes inoperative through corrosion (especially the MUV fuze family). When plastic-cased fuzes were used, past bushfires may also have rendered them inoperative, or softened the plastic so that the firing pin has fired backwards and is no longer present (effectively removing their intended means of initiation).

Note: Some argue that a corroded mechanism is less predictable than a pristine example and so should be seen as a greater risk. When the mines are OZMs or POMZ-2/M with MUV fuzes, Deminers do not agree - because the fuze system is exposed and usually visible for them to assess. Other mines, such as the J-69 (South African copy of the VALMARA-69) has a hidden fuze mechanism so its condition cannot be assessed. Deminers always treat these mines with the utmost caution.

Some mined-areas have been fought over and many contain a mixture of mines and UXO. The picture below shows a collection of finds from such a field.

 

1.2 Typical ordnance threats in Southern Africa

These can be divided into:

Rifle and shoulder launched grenades and projectiles
Hand grenades and small arms ammunition

Mortar bombs
Rockets
Air dispersed bombs
Submunitions
Artillery and cannon shells
Fuzes and boosters for any of the above

The injury that could be expected from these munitions varies but many could kill whatever protection a deminer was wearing. However, the most common recorded accidents with munitions other than mines during Humanitarian Demining activities have only involved a fuze/booster. In these cases, injuries are usually light and could be avoided by the use of appropriate PPE.

The risk posed by each threat/device is not assessed solely on the device type, also on a combination of its condition, fuze mechanism and context.

Generally if these devices have not been fuzed and are in good condition, the threat they present is considered to be very low. If the device has been fired, the threat can be high depending on the fuzing system. With shoulder launched grenades and projectiles, a basic knowledge of the fusing system is essential because some are intended to "self destruct" if they do not detonate on impact. If they do not "self destruct" they can be very sensitive to movement. Similarly, some anti-armour hand-grenades and many submunitions have unpredictable fuze systems and can be very dangerous to move. Many must be destroyed where they are. In contrast, most common high-explosive mortar bombs that do not detonate of impact are found in good condition and are routinely moved to a demolition pit for later destruction. The same is true of many (but not all) commonly found RPGs (Rocket Propelled Grenades).

Whether fuzed, fired, or abandoned, if a propelled device is in poor condition, the threat of ingesting volatile propellants and from accidental ignition of those propellants can require specialist knowledge in order to make an appropriate assessment. When a device is in poor condition and contains phosphorous based incendiaries, the threat of the incendiary igniting on contact with air when the device is moved can be high. In many cases, specialist knowledge is not available and the deminers simply destroy the device using large amounts of explosive without moving it. (Deminers responsible for demolitions are usually trained to discriminate incendiaries from high explosive munitions in order to avoid disposing of incendiaries unsafely.)

There is evidence that (after the return of Internally displaced people and refugees) unexploded devices (fuzed) cause at least as many civilian casualties as mines. When civilian safety is the main concern, this makes the removal of UXO at least as important as the removal of mines.

 

2. Context

The context of the mined-area is also highly relevant, affecting ease of access and detectability, so altering the degree of risk involved. The following is an incomplete list of contextual variables that may affect the Risk Assessment in a particular area:

    • Areas that are heavily overgrown present a greater hazard than those where undergrowth is sparse. This is true even when the mines are not tripwire operated because the deminers cannot see what they are approaching, which may be an obstruction, trench etc.
    • The hardness of the ground can seriously increase the risk of an unintended detonation when excavating detected devices.
    • The electromagnetic qualities of the ground can severely affect metal-detector performance. The presence of large quantities of scrap metal can also seriously affect metal-detector performance.
    • The presence of obstructions, (boulders, burnt out vehicles etc) can significantly hamper access, command and control lines and the choice of resources to deploy.
    • Proximity to power lines, reinforced concrete, buildings, power lines and transformers can all affect the performance of metal-detectors (and may adversely affect field communication systems).
    • Battle areas may be heavily contaminated with traces of high explosives that affect dog performance.
    • Any mines that have been placed on a steep area are at high risk of having been moved by heavy rainfalls and their original orientation may have changed. They may also have become deeply buried.
    • Sharp stones and thistles/thorn bushes (cut or intact) can seriously inhibit the use of dogs without foot protection.
    • Steep, irregular or damp ground can also seriously affect the use of machines in ground preparation and the deployment of manual deminers.

2.1 Weather

Extremes of wet and dry conditions can increase the mined-area hazard by changing the properties of the ground. Rain can soften the ground surface and make it easier to safely excavate, but rain may also change the electromagnetic properties of the ground and make devices harder to detect with a metal-detector. Excessive heat and humidity can affect the performance of deminers and may dictate a change to the working hours or the frequency of rest periods.

 

3. Experience of the work to date

Risk Assessments are varied by experience in the particular mined-area. For example, the threat assessment will change according to the devices found.

The risk assessment may be high when tripwire operated mines are known to be present. This may mean that a decision is made to clear all undergrowth using machines prior to manual demining. After a significant number of the mines have been found and none of them had intact tripwires or were capable of easy initiation by incautious handling, the risk assessment may be reduced. It may then be decided that the mechanical assets are better deployed elsewhere or in another way, and the clearance of light vegetation might take place manually.

In another case, a minimum-metal mine may be found in an area where it was not anticipated. To achieve confident clearance to the required depth, alternative detectors, dogs or ground preparation methods may need to be used.

Changes to the context such as unexpected wet ground, obstructions, trenches, abandoned military equipment or changes in the electromagnetic properties of the ground may require a change to the site management or to the resources deployed.

When the threat assessment or the context changes significantly as the work progresses, the original Risk Assessment should be examined and appropriate changes to the working methods adopted. This may have a negative impact on the projected cost of the task, but should always improve safety and confidence in the thoroughness of clearance. When a revised Risk Assessment has a negative impact on cost-effectiveness, the managers of the demining group must accept safety for the deminers and the end-users of the land as their first priorities.

Click on: Example Risk Assessment so see an example. It is not typical because it was assessing the risk for a research group, but the principles are applied.