Sustainable development is a process which 'meets the needs of the present without compromising the ability of future generations to meet their own needs, ' according to Our Common Future - or the Bruntland report, as the 1987 World Commission on Environment and Development is better known.
But to British Geotechnical Association chairman and Carillion chief engineer Quentin Leiper, it is about 'not cheating on your grandchildren' For BRE director of geotechnics Richard Driscoll 'there are several strands to sustainability - not least the recycling of land and all that it entails' This and the reuse of existing foundations are the main things he associates with the issue of sustainability and geotechnics.
He says: 'Designers would like to reuse existing foundations more, but lack the means to demonstrate that the change of use of a structure - with the resulting different loading on piles, for example - can be done effectively and reliably.'
Together with the remediation of brownfield sites, the reuse of foundations is high on BRE's sustainability agenda.
Driscoll would also like to see the geotechnical community improve its approach to managing risk, and sees this to be closely tied in with the sustainability debate.
Finding better ways of identifying and managing risk would result in less conservatism, fewer failures and the avoidance of the waste these entail, he says.
Leiper believes the construction industry is being forced to address the more complex issues of sustainability and the life-cycle impacts associated with the built environment.
This, he adds, 'represents a significant challenge for an industry sector where the supply base is large and fragmented and where most projects have unique requirements.'
He says sustainability in geotechnics needs to grow from within industry, not by having the concept thrust upon it - 'As an industry we ought to be ahead of legislation.'
In this respect, Carillion is running at the front of the pack. It has developed a sustainability score sheet to audit its supply chain. It is early days and this, says Leiper, 'is a benchmarking process to see where we and our suppliers sit.'
Earlier this year, the Department of the Environment, Transport and the Regions published its Sustainable Construction Strategy, Building a Better Quality of Life. This document sets out how the construction industry can contribute to the achievement of sustainable development through, among other things, enhancing and protecting the natural environment and minimising its consumption of energy.
Stephan Jefferis, Professor in Civil Engineering at the University of Surrey, says the Government has put a strong social spin on sustainability and is determined to put people at the centre.
'It's a laudable aim, but would we need a concept of sustainability if a people-centred world could achieve it?'
Jefferis questions whether sustainability has any more weight as a vector for change than, say, risk. He cites the Bruntland report and its references to 'inter-generational equity' as a serious underlying agenda but remarks on what he sees as a 'lack of glowing examples' within the geotechnical community.
'There is research on sustainable waste management, but I am not sure that it will change future practice, as it is more focused on trying to tidy up past messes, 'he says.
Past messes need to be addressed, and contaminated land, he says, poses an interesting problem: 'Our parents and past generations gave it to us, and intergenerational equity may require us to pass some or much of it on to our children.
But is it a high enough risk to spend so much money on?
Would a few new hospitals be better?'
He argues that there is a fundamental tension between sustainability and development. Development may enable social welfare but hinder sustainability.
CIRIA's Fin Jardine is less cynical. He believes that the UK's geotechnical community as already gone a long way in its efforts to embrace sustainability.
He says: 'It is already in the ethos of the professional community and there are very many industry-generated activities that seek - and succeed - in improving practice, many of which now have an overt environmental agenda.'
The geotechnical industry has put a huge amount of effort put in by to the development of good practice guidance, Jardine says.
'And I know better that anyone, because of the huge support CIRIA projects have been given in areas covering methane and landfill gas, contaminated land, waste engineering and also on the Construction Industry Environmental Forum activities.
'I would argue that all the geotechnical engineering research projects on which I have worked at CIRIA have had sustainability as an underlying aim.'
This, he says, means doing things efficiently and economically, minimising - if not avoiding - waste, working with rather than against nature, protecting and preserving what is there already, cleaning up or containing, and improving practice.
He is, however, 'prepared to be cynical' about clean-up because it is profit-driven: promoting so-called 'environmental and sustainable' methods makes commercial good sense.
A lot of what is done is 'too little, too late' but 'better some than none and better late than never.'
He is adamant, however, that he will not be cynical about geotechnical people: 'They have a humility about nature's materials, the risks of which they have to manage and they are anything but wastrels.'