What lies underneath

The recent controversy about the proposed extension to the museum of St John's Co-Cathedral in Valletta has indeed raised a number of questions about the presumed stability (or instability) of the ground below our architectural heritage. Many well-intentioned opinions were voiced about the risks of carrying out excavations next to what is considered a national treasure. Too much was at stake, considering our national pride and considering our confidence in the key players within the construction industry.

The museum extension saga clearly shows that, as a nation, we yet have to believe that an excavation can be carried out in a professional manner that causes no distress to its surroundings. Too many people have experienced inconvenience or damage to their property due to neighbouring excavations. Developers and contractors who did not know their limits have ridden roughshod over too many people. Too many suffered unpleasant consequences because the protection offered by those responsible for the regulatory framework is, at best, rudimentary. It is therefore not surprising that the museum extension project was shot down before the EIA process had even started.

This state of hysteria, hijacked, as it were, and maybe justified in the circumstances, need not be a permanent characteristic of our country. There are ways and means through which excavations can be carried out safely, even in the most difficult of situations. Doing so requires a multi-disciplinary effort from all stakeholders and a more structured approach to the way we go about assessing and implementing such projects. As architects Andrè Zammit and Alex Torpiano pointed out in their letters to The Times, there have indeed been great advances in the civil engineering fields of rock mechanics and geotechnics, which allow excavations to be carried out safely. These range from the investigative methods used to obtain information about the ground, the numerical methods used to process this information and the construction technology available to mitigate the risks involved. I will not delve into the details of each of these, but it is sufficient to mention one relevant example to demonstrate what is achievable.

The Houses of Parliament and the famous Big Ben Tower at Westminster in London are perhaps two of the best-known iconic landmarks, not only to the British, but to the entire world. Would anyone think of undermining the foundations of these famous buildings, built on the relatively soft clays and gravels of the Thames?

Well, that is exactly what was done, not once but twice in rather rapid succession. The first project, carried out in the 1970s, consisted of building an underground car park for parliamentarians. A six-storey hole needed to be excavated, partially below the water level of the river, 16 metres away from the Big Ben tower and three metres from the Houses of Parliament. At best, foundation movement would have resulted in the world famous clock gaining or losing time, not to mention the more serious and obvious consequences. Extensive studies were carried out, computer models were created and the best minds were put at work to carry out such a delicate operation. The car park is now there for all to see, constructed not in the conventional manner but by building it from top to bottom.

Two decades later, in 1995, London Underground Ltd decided to extend the Jubilee Line and the rebuilding of Westminster station was conceived. This time, a 13-storey underground hole in the river clay, accompanied by tunnels, needed to be excavated across the street from Big Ben - the deepest basement ever constructed in London. Not only was it carried out, but the resulting underground structure is indeed a triumph of engineering and an experience to visit. Big Ben still chimes away the hours - perfectly on time...

As a country, we are blessed in that there is plenty of rock to erect our buildings on. Unlike other urban locations, which developed on the banks of a river, we have very little soft soil to worry about and our geology generally provides sufficient load-bearing capacity, even though it is not composed of the strongest of rock strata. This does not, however, imply that any intervention can be taken lightly, as many unfortunate house owners can attest. But it does mean that safe solutions can be found if we put our collective minds to it.

Flimkien għal Ambjent Aħjar and all the others that voiced their dissent against the museum project were right in doing so. We still do not possess what it takes to carry out projects like the Big Ben car park and it is not simply a matter of technical competence. It has to do with the way we, as a nation, approach the deceptively simple task of thinking about, approving and executing a hole in the ground. We may or may not have a satisfactory EIA process (depending on your point of view) but that, on its own, does not guarantee that an excavation is planned and carried out as it should.

It is neither a matter of engaging foreign expertise for the particular project, as we normally tend to do. It goes beyond that and in my opinion requires a re-think of the way we do things in all relevant sectors. I will attempt to give some examples.

Further research needs to be carried out on our geology from the geotechnical point of view. This will help us to better understand what is happening within the complexity of ground materials as we change them to our liking. Legislation in this regard, currently bordering on the irrelevant, needs to be amended and new policies regarding excavations drafted and implemented.

Society needs to have better checks and balances to ensure that whoever is carrying out an excavation knows what he is doing and that he has actually done his homework. Construction and excavation methods need to be updated to current technology, both via continuing professional development and by the application of new techniques on the building site.

Development in this sense should include all key players and maybe even go as far as the individual site operatives, giving them the opportunity to learn about and be trained in handling the brute force of their machines.

All this needs to be done for the sake of a rational, open-minded approach towards projects like St John's. More importantly, it needs to be done because of that dreaded planning authority notice indicating that, soon, a big hole will be formed next to your front door.

The author, a director at iAS Consulting Engineers, is a geotechnical engineer, currently lecturing in soil mechanics and geotechnics at the Faculty of the Built Environment, University of Malta.

www.ias.com.mt, adrian.mifsud@um.edu.mt