Probably the biggest danger to anyone involved in the construction industry where there is a need to carry out any sort of ground excavation work is the chance of hitting something underground such as an electricity cable, gas pipe, sewage pipe, and so on. The problem is that these underground services can be just about anywhere, including in some of the most unlikely situations.

Fair enough, if you are going to dig in the High Street where there are shops and offices, or a residential street, you know that there are going to be electricity cables, possibly gas pipes, telecoms, sewage pipes, and so on. But out in the middle of a field?

Yes, it can happen. For instance, in some areas out in the countryside where there may be small villages or hamlets, they all need electricity and telecoms, and sewage pipes, and so on, and it may be that the shortest distance between two hamlets is across a field that was full of sheep. So that is the route that the utility provider decided to take, and it’s fair enough. But it should give you pause for thought that, wherever you are going to dig, there can be underground services. And in turn that means that you need to take every care to locate and identify underground services wherever the contract may take you.

What is astonishing is that there are estimated to be about 4 million excavations across Great Britain every year, yet in 2017 only 2.25 million of these were preceded by a thorough search for pipes and cables before any digging began. That means that some 44% of all excavations were carried out without any detailed search for underground services in the area!

60,000 Cable Strikes A Year Can Be Easy To Understand

When you look at figures like that, it is easy to understand why there are some 60,000 cable strikes in the UK every year. In fact, in some respects it is surprising that there are not more. The big problem is that many of these cable strikes result in serious injury, and indeed are sometimes fatal. There are around a dozen fatalities each year in the UK as a result of a cable strike – and all because someone could not be bothered to carry out a full and proper survey before commencing the work.

One of the most important things that you can do if you are going to carry out any excavation work is to obtain a copy of HSG47 which is a guide produced by the Health and Safety Executive providing detailed information on what you should do to check for underground services before doing any digging.

The two main tools that are used when searching for underground services are the CAT and the Genny – Cable Avoidance Tool, and Signal Generator. These are a great pair of tools for location and identification of underground services, but it has to be emphasised that they are not infallible. They do have certain limitations. So, it is not just a question of taking them out of the box and reading the instructions.

This is why, at Sygma Solutions, we provide an HSG47 course which goes into great depth on what you need to do when carrying out such a survey and how to use the CAT and Genny to best advantage. For example, when using GPR it can sometimes be very difficult to push the unit over very rough, stepped, or uneven ground, and the unit needs to be very close to the surface otherwise it will not operate. In addition, if the ground is very wet, and the services are buried in heavy clay soils or lots of rubble has been backfilled, it may be near impossible to get a return signal or to allow correct interpretation of a signal received.

All of these things are explained and taught on our HSG47 course which will enable operatives to make the best use of CAT and Genny, while still allowing for the fact that their may be limitations as to what they can do in certain circumstances.

Even when underground services have been identified and traced, it is still essential to proceed to dig with caution. There could still be services there which are dead or untraceable, such as certain HV cables which are designed specifically so that they do not give out any passive signal whatsoever.