The Civil Engineering Contractor October 2018 | Page 33

INSIGHT
piling as an example, if there is a
dry stable profile with rock relatively
shallow, one can drill the piles in an
open hole, clean the base of the pile,
place the steel, and cast the concrete;
it’s quick, it’s easy, it’s cheap. But if
a piling contractor hits a water table
at a certain point, particularly within
weak soil, the sides of the hole may
collapse with water ingress. This can
then have a massive impact on the cost
of the piling. Contractors therefore
need as much information as possible.
“During the course of our work, we
get to review and utilise reports from
many different companies, engineers,
and engineering geologists. While
there is a lot of excellent work being
produced, there is also, to be frank,
some complete rubbish,” says Green.
One problem with geotechnical
reports is that there are limited legal
requirements for them, with the
exception of very specific statutory
requirements governing work
involving dolomite because of the risk
of sinkholes forming underground,
and the NHBRC which reviews
geotechnical investigation reports on
residential developments. “In the case
of geotechnical investigation work for
commercial or industrial development,
while sometimes a bank will insist upon
a geotechnical report and sometimes a
structural engineer will insist upon one
to have a basis for their design, there is
otherwise no legal requirement.”
He cites major commercial
developments in Gauteng where large
basements were being constructed and
the geotechnical reports were under-
specified and did not even extend
to the level of the bottom of the
basement. One such project had issues
with the founding of the structure, as
they were expecting rock at the base
of the excavation, which did not turn
out to be the case. “By the time you’re
there and have to change everything,
it causes delays. A two-month delay
on a project with a R200  000/day
penalty gets expensive very quickly,
and these seem to just get absorbed in
the development cost as it proceeds
and not much spoken of. Physical
collapses or disasters are actually fairly
rare because contractors and engineers
are used to monitoring and adapting
“Because of this issue of the sometimes poor quality of
geotechnical reports, the SAICE Geotechnical Division
has been trying to improve the situation. To this end, we
published a Code of Practice on site investigations in 2010."
as they go along. Financial disasters, I
suspect, are far more common.”
“It is brushed under the carpet, but I
sometimes think it would be better for
the industry if these issues were more
transparent.” He says this in his role as a
voluntary member of the South African
Institute of Civil Engineering (SAICE),
where he used to head the geotechnical
division and remains actively involved.
“Because of this issue of the sometimes
poor quality of geotechnical reports,
the SAICE Geotechnical Division has
been trying to improve the situation.
To this end, we published a Code of
Practice on site investigations in 2010.
That is not a statutory requirement,
and nobody enforces that you use it,
but at least it is a reference document
that can be used to say that ‘this is
the minimum requirement for an
investigation’. You would be surprised
how often even the basics are ignored.
For example, you should