The Civil Engineering Contractor June 2019 | Page 29

FEATURE
own designs at a cheaper price,
meaning they then had to take full
responsibility for that aspect of the
work. Geotechnical contracting has
been heavily biased towards this
model over the past 25 years, though
there are signs of it coming a little
more into balance in recent years.
“Design and construct type
contracts come with their own
challenges – because you’re
now designing something with
a commercial incentive to win a
tender in an environment where
there is not a lot of work. Therefore,
contractors and their designers
start pushing the design right to the
ragged edge. As designs get pushed
further and further to save costs,
you’re bound to get some problems
as everyone is incentivised to take
more risks. Arguably, an engineer
designing directly for the client has
less commercial pressure and would
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find it easier to build to appropriate
levels of safety,” says Green.
It’s easy to find examples of the
sorts of things that can go wrong
when the envelope is pushed too
far, such as under-designing lateral
support resulting in cracks in
neighbouring buildings or under-
designed piled foundations resulting
in settlement of the structure. Either
way, small savings do not justify the
risk, especially when it comes to
anything geotechnical.
When a proper geotechnical
investigation report is done, the
blame for any subsequent problem
may be laid at the door of the
engineer or contractor. But if poor
or inappropriate investigation is done
the client has limited recourse, as the
engineer or contractors have the right
to claim they were working with
faulty information. This is the perfect
recipe for contractual claims, legal
claims and counter-claims.
“In eight cases out of 10,
there may be no problem –
but in the other two cases out
of 10 the blowout on costs
makes it worthwhile to have
done reports on all 10.”
Piling’s perspective
Tera Strata’s Nell says his firm does
design and construct projects most of
the time and the relationship between
the geotechnical report and piling and
lateral support is ‘100% symbiotic’.
Geotechnical construction companies
do not generally do geotechnical
reports; mostly they just provide the
drilling equipment necessary.
“We need the geotechnical report
to do the design and to assess the
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