Causing damage to underground services during the course of a project can have severe repercussions. Not the least of these is the risk of injury – which can be serious and is sometimes fatal – but it can cause delays to the project, environmental damage, and incur considerable costs. It can also severely harm the reputation of the contractor concerned. All of these are very sound reasons for following the guidelines of the HSE in its publication HSG47 (Third edition) published in 2014 which is entirely concerned with the avoidance of striking underground services. One of its’ key points is that underground services are widespread and that you should assume they are present unless you have been shown otherwise.

If anything, one should take this a step further. It is quite possible that you might take all the right steps when planning the work and have obtained plans – or STATS – from the utilities in the area. This may show that there is nothing in the area in which you need to work. However, the STATS are not always accurate and up to date, the result is that they could give you a misleading impression. The safest thing to do is to assume that services are present – full stop. The STATS should only be used as a guideline.

It is essential to undertake a survey of the area to be worked upon using the CAT and Genny for cable avoidance. These tools work very well when used in combination. While it is possible to use the CAT on its’ own, in power mode it can only detect cables that have power running through them.

If you are confident that you will only ever be searching for power cables and that all the cables in the area will have power running through them when you are searching, then it could be argued that you only need the CAT. However, if you cannot be absolutely certain that this is the case, then you also need to use the Genny.

Even if you use the CAT and Genny together, they still have certain limitations, and this is why all operatives who are going to have to locate underground services need to attend one of the training courses that we run at Sygma Solutions. Our courses cover absolutely everything that you will need to learn – including the limitations.

Just to take one simple example, you might use the CAT and Genny to survey the area and produce a result which is negative. On that basis, a worker could start to dig and strike an underground service that the CAT and Genny told you was not there! This could be because the signals can only penetrate to a certain depth – let’s say a metre. So if there was a service at a depth of one and a half metres, it wouldn’t show up. The correct thing to do is to proceed to dig carefully, and then when having got down about a foot or so, use the CAT and Genny again. You might still get a negative result, meaning that you could dig down another foot. You should then take another survey, and this time the CAT and Genny might locate the service. These are some of the things that we teach at a Sygma Solutions training course.

Injuries caused by striking electricity cables are usually caused by the explosive effects of arcing current and are often severe burns to the hands, face, and body, which may be fatal. Electric shock is also possible, but less likely. Nearby services such as plastic gas pipes could also be at risk from live electricity cables that have been damaged.

Damaging gas pipes themselves can cause leaks that may result in fire and explosion. Leaking from liquid petroleum gas pipes can be more serious than natural gas as it is heavier than air and can travel long distances underground and accumulate in cellars or underground car parks.

Damage to water pipes may not be so serious, although a jet of water under pressure can cause injury, and it may also contain stones or other debris from the ground. There may also be flooding and risk of an excavation collapsing. Damage to telecoms can be extremely expensive to repair, although unlikely to cause injury.

All of this, and a lot more, is contained within the courses that we provide at Sygma Solutions.