Damaged foundations can result in civil litigation
I was contacted recently by a good friend in the U.K., Len Threadgold. Len wanted to know how geotechnical investigation services are procured here. This kind of investigation determines the physical properties of the soils and rocks that support foundations. Engineers use this data to design the foundations.
Such an investigation is needed at every site because the foundation soil and rock conditions vary from site to site and across a site. I learned when I practised in the U.K. to “Expect the unexpected” when assessing foundation soil conditions. A similar mantra goes into the field with every geotechnical engineer in Australia – “If in doubt go deeper” – to stronger soils. I had that drilled into me down there too.
Len is chairman and chief engineer of Geotechnics Ltd., a geotechnical and environmental engineering firm with offices in several cities in the U.K. He was recently awarded the John Mitchell gold medal by The Institution of Civil Engineers (ICE) for “Excellence in geotechnical practice”. Len will give a talk in London at the ICE on January 24 on Re-thinking Site Investigation – Design, Practice and Procurement to commemorate the award.
How is all this relevant to forensic engineering investigation? Because many, if not most foundation failures are due to inadequate investigation of the ground which supports all building and civil engineering construction. Damaged foundations can result in civil litigation.
Why are the investigations inadequate? There are different reasons including foundation soil investigation services that are too often procured on the basis of low price in Canada and the U.K.
The barest minimum investigation is (too) confidently recommended in the interest of keeping costs down. This can lead to foundation failure and major cost overruns – there’s no money in the quote for chasing the evidence across a site if unexpected conditions are found. Cost and bottom line trump quality.
Often enough no investigation is carried out and hope rather than engineering analysis prevails.
Some studies in the U.K. indicated that project cost overruns due to unexpected ground conditions amounted to about 17.5% of project cost for highways (Ref. 3) while the cost of geotechnical investigation was on average 0.21% of project cost. Cost overruns were 83.3 times as much as investigation costs! If the difference between quoted prices for site investigation was 10% then this ratio becomes 833!! (Ref. 4) – not a sensible cost-benefit ratio.
So decisions on who to retain for a geotechnical investigation are based on trivial amounts of money, amounts much less than the cost of the reception desk in some offices and probably the cost of the opening ceremony. (Ref. 4)
I can’t help but think a similar situation exists here in Canada.
(Nor can I resist noting that some people shop around for expert forensic services on the basis of low price, and similar problems with inadequate forensic investigation may well result)
Parents instill confidence in us but remember Mom is just below the ground surface ready to scold if we accept low quality to save a dollar.
- After, Professor, Sir A. W. Skempton, U.K., “Optimism and overconfidence may impress one’s clients but they have no influence on the great forces of nature”. Address of the President. Proceedings of the 5th International Conference on Soil Mechanics and Foundation Engineering, 3, 1961, pp 39-42.
- Clint Eastwood in the “Dirty Harry” movies, 1971 to 1988
- Stuart Littlejohn, Inadequate Site Investigation, The Institution of Civil Engineers, U.K., 1991
- Personal communication with Len Threadgold, Geotechnics Ltd., U.K., 2017 (An initial chat with Len on his ICE award gave me the idea to blog on this topic of inadequate geotechnical investigation, foundation failure and civil litigation)