I recently undertook a two day NVQ course in CAT and Genny training, this was 2 days dedicated to learning how to push a button on a CAT (Cable Avoidance Tool) and use the associated Genny (Generator) to produce a current that would allow a suspected cable to be detected. Now I’ve been using a CAT for years, it’s not rocket science, pick up the tool, hold in the button and walk slowly over the ground. If the CAT beeps you have a live cable, if it doesn’t beep then there is not a live cable on the line that you are walking. Therein lies the key, a LIVE cable, because folks the CAT only picks up a current. So, a cable that is used once a day at 5pm to power a kettle will not have a current passing through it at any other point as so will not be detected by the CAT, despite qualifying as a LIVE service. (Yes I know two days to learn this seems like overkill).
The thing is, in undertaking archaeological works we do run the risk of hitting live cables. Whether we do a trenching job or strip a whole field we are taking off enough ground surface to expose and/or encounter underground services, and not just electric ones. Buried under the ground alongside archaeological remains are electric cables, gas pipes, water pipes, both fresh and foul, sewer pipes, fibre optic cables, telephone wires, high pressure oil pipes and that is before we look at random unknown cables that may be there. Mostly the associated gas, water, or electric board can provide plans of where their underground service runs should be in a particular area. However there is one telecoms company (that shall not be named) that never seems to know where its own cables run – I went through one once and even the chap who came out to take a look at it couldn’t work out if it was the current run of new cable or an old defunct line. Sometimes you find yourself wondering how you can possibly be expected to avoid these things.
As such I can tell you all that I have, accidentally of course, cut my way through: an illegally installed gas pipe (no service plan as not registered) 10 cm below the ground surface, an old gas pipe listed as no longer in service (boy oh boy did gas come shooting out of that thing), three telecom cables (located two fields away from their planned routes), an unlisted water pipe, a high pressure irrigation pipe on a golf course (apparently turned off and no longer in use but the 2 day water spout in the photo below would tell a different story) and the finest of them all – the electricity cable providing power to a church 30 mins before a funeral. Fortunately, in this case I was simply observing a job being performed by the electricity company and they had the whole thing up and running again in no time – phew.
Now you might be wondering, am I really unlucky or am I terrible at spotting these underground services? The answer is neither – my list of gaffes is small compared to others, for instance I’ve never had the military land a helicopter on my site because I touched their oil pipe (happened to a friend of mine), nor have I electrified the tracked excavator, or cut power to a restaurant for 3 days, or cracked the main sewer to a high street. Accidents happen, but they are preventable. Modern service runs, like any intervention into the ground, leave a mark in the surrounding soil. Go outside and look at the road, I’d bet that you can see a line in the tarmac running from one metal manhole cover to another just like in the image below?
That is what we look for, usually, if the job has been done right an electric cable will be buried more and half a meter down covered in 0.10-0.30m pea shingle with a long plastic tape reading “Caution live electrics”. When that happens we can see it no problem, avoid it and everyone is happy. What we can’t see and have no chance of avoiding are those buried 10cm below the surface, or those that are not listed on plans. It’s an inevitability of working in construction, at some point you will hit a cable. Fortunately health and safety is getting much, much better at ensuring everyone is trained - hence the 2 days on how to use a CAT and I have another training day scheduled for avoiding overhead cables, which you’d think would be obvious, but strikes happen. It only takes a momentary lapse of concentration and bang, something has gone wrong. I’ve been lucky – none of my breakages have resulted in injury and/or lost time, though they’ve cost a bit of money in some cases but were still ultimately unavoidable. Others have not been so lucky. So whilst commercial archaeology may not be all escaping gun toting bad guys, rolling boulders, or manic heart-ripping-out cults, we do face our share of dangers, but as health and safety becomes more of a priority across the construction industry we hope to reduce the number of encounters with modern services thus keeping everyone safe, and your kettle running!
S. M. Porter
Professional archaeologist and author, S. M. Porter loves history, adventure and digging in the mud. Her career is in ruins - just where she wanted it to be.