Integrating archaeology into geotechnical surveys

Dear Colleague

Unexpected archaeological discoveries can cause costly construction delays. There are number of things which AGS members can do to reduce archaeological risks and help better preserve our heritage as well.

One of the simplest is recording archaeology, as well as geotechnical details, from boreholes and test-pits. The added cost can be minimal but the information gained can forewarn of potential problems and help further archaeological studies, later in the development, to flow more smoothly. The whole project can benefit – and the client’s costs can be reduced.

Terra Nova Limited has carried out a study of ways in which archaeological recording could be better integrated into geotechnical site investigations.

You can find the report on our website at www.terranova.ltd.uk

We need your comments to find out if the idea of closer integration could ever be widely accepted – and how this might be achieved.

If you already build archaeology into you site investigations or coordinate geotechnical and archaeological studies from the start we would like to hear about your experiences.

If you haven’t integrated work in this way what would be your main concerns? What might persuade you to do so?

We have tried to angle the study towards the practicing geotechnical engineer but it is also intended for archaeologists, since the push for integration would have to come from both sides if it were to succeed.

Thanks for your help

David Jordan
Director, Terra Nova Ltd

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Unexploded Ordnance

Dear Sir

We are becoming increasingly concerned about the activities of some of the companies that offer threat assessments in respect of the risk of encountering unexploded ordnance on a site, (either during ground investigations or piling and excavation / construction etc). Usually the ordnance that might be present relates to unexploded wartime bombs (UXB). We are writing to see if any other member organisations have similar concerns.

We have commissioned a number of these desk studies / threat / risk assessments, with the results that basically if the site is anywhere near what was a built up area in the south of England during WW2, or an industrial area, port or military installation anywhere in the UK, then the results always seem to conclude that there is a risk (not really quantified) of UXBs being present and then go on to recommend / suggest expensive precautionary measures during investigation and development. This includes probing / magnetometer surveys etc in advance of each borehole, and it can double or treble the cost of the GI. The same measures would need to be put in place before piling also.

However, in most cases it is the very companies that offer the expertise to do the threat assessments that also carry out the ordnance clearance works that are needed. There is a potential conflict of interest here. Also, we have been unable to obtain quantitative assessments of risk (other than low / medium / high) from the companies concerned, so we cannot give objective advice on the actual degree of risk to our clients. This service sector appears to have a problem in quantifying the risks involved and we as an industry should be concerned about the consequences.

To put the risk in context we have had a brief canvass of colleagues in the industry and this suggests that there is only one recorded incident of an UXB being detonated by ground investigation or foundation construction activity and that was by a piling rig in Berlin, which must have been bombed much more heavily (and with larger bombs) than the UK.

We accept that there is an enhanced risk in heavily bombed areas such as the Thames Estuary / London Docklands, other docks and near major military sites etc, but not generally in many parts of post WW2 London and the south-east or in industrial areas away from docks further north. We believe that for many sites the cost of the special precautions recommended by the firms involved is not justified by the actual risk, but it is very difficult to ignore recommendations or suggestions in reports by these specialists once you have commissioned them. Equally as responsible Engineers, it is difficult to justify not commissioning the threat assessment in the first place for many parts of the UK.

Several of our major developer clients have also expressed concern at over-zealous safety requirements arising from such assessments and their feedback is that some of our consultant competitors do not appear to address UXB risk at all. Of course, as a practice we take an extremely responsible attitude to safety, which is of paramount importance, and it is essential that we respond to risks if they are genuinely present. However, we have no desire to be perceived by our clients as over-cautious in this particular respect, with a more expensive outcome for the developer.

We fear that this is going to become an even greater problem in the future as we all become more safety conscious and risk averse.

Perhaps the answer is for practitioners such as ourselves to develop their own independent expertise in carrying out such threat assessments on a quantitative numerical basis, so we do not have to rely on those that also carry out the clearance work. Then we would be able to give our clients objective advice on risk.

Are there other members’ concerns about this? Is this something AGS should be looking at, perhaps with FPS if there are similar concerns? Is there experience elsewhere in Europe to draw on? We would be pleased to hear the views of the Association.

Richard Thomas
Senior Associate
Peter Brett Associates.

Editors Note: Do you have a view on this issue – or anything else in the Newsletter? Feedback (whether or not for publication) is always welcome at the AGS office