Seminar highlights urgent need for piling records

Experts at STATS seminar fear that major developments in London will face significant problems as a result of the mass of piles, foundations and services beneath the capital's surface.

Speaking at a seminar arranged by consultancy firm STATS, entitled Recycling Foundations, key industry figures also revealed how problems encountered in London will soon appear in other UK and European cities and how these issues can be addressed in a sustainable manner.

Key factors affecting constraints on new piling include the London Underground, canal routes, electric cables, telecommunication and sewers.

This in turn means that there is more emphasis on the re-use of old foundations instead of piling in rapidly diminishing spaces.

Tim Chapman, Director at Arup, explained that the viability of re-using old foundations is difficult due to the poor accuracy and limited availability of old records.

Additionally piling close-out reports are uncommon making it even more difficult for developers to consider re-using old foundations.

At the seminar he said: "The importance of keeping close-out reports cannot be underestimated.

We need to ensure that specifications, method statements and pile plans are all kept and recorded so that in the future developers will know exactly what is beneath the ground.

"We are seeing major problems in London now and these will soon appear elsewhere in cities such as Manchester, Paris and Madrid".

Commenting on the sustainability aspects of foundation re-use, he added: "The best thing you can do for the planet is to forget about changing your lightbulbs and commission piling close-out reports".

The issue of housing all records in a central records office, as in Sweden, was also raised, but STATS Director Dr Shon Williams, explained that this would be a huge challenge to undertake and require significant political intervention and financial resources.

Instead, he claimed that the onus should be on the site owners.

He said: "Property owners must take their responsibility seriously and ensure that accurate records are preserved.

The bottom line is that we are running out of 'new' space to develop and so we have to look at existing sites and old foundations.

If the records for these sites do not exist there are a number of ways in which existing piles can be tested, including petrographic investigation, non destructive testing to determine pile length, drilling boreholes to establish ground conditions and static/dynamic pile testing".

"Deterioration and the deformation characteristics of old piles need to be assessed before the possibility of re-use can be entertained.

Pile integrity can be affected by a number of serious issues, including necking, horizontal cracking and chemical attack on concrete and reinforcements".

Indeed, he said it was 'essential' to assess the structural integrity of existing piles to ensure they have not succumbed to any of these problems.

Also at the seminar Edwin Bergbaum, Director (London and South East) of Waterman Structures, highlighted the benefits of re-using foundations by giving examples of several London developments including the transformation of Mondial House on the River Thames.

He explained the benefits of re-using piles include cost, time, sustainability and fewer on-site activities, whilst the disadvantages included greater risk and a more complicated construction process.

Many of these points were covered further by Dr Ian Sims (STATS) during his talk on Assessing Concrete Materials in Foundations.

He focused on methods of assessment and the various aspects of concrete durability that need to be assessed before old foundations can be re-used.

Although concrete materials in foundations can often be investigated in the same way as those in superstructures, he explained that some threats to concrete are exacerbated in certain ground environments.

Additionally, any deterioration is likely to remain concealed until discovered by accident or at the time of assessment.

He also covered ways of gathering evidence from concrete, including microscopy and chemical analysis in order to determine its health.

Key deterioration types included weathering, leaching and reinforcement corrosion.

Finally, Professor John Atkinson summarised the day's key points by saying: "Overall the event covered many areas that need to be looked at when considering the re-use of foundations.

Perhaps the most important factor being whether there are reliable records of the existing foundations.

There has been a clear call for comprehensive records to be kept and safely stored.

There are still a lot of unknowns surrounding the re-use of existing foundations and there is a strong message that this is best avoided." Summarising his views on the future, Tim Chapman (Arup) said: "I wish I had shares in Foundation Re-use - if such a thing existed".

Back to top