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PLUMBING CONNECTION
SUMMER 2016 51
Design Manager at Cooke & Dowsett Mathew Yanez
has recently drawn up a solution for a Bunnings store
in Yarrawonga, Victoria, being built on reactive soils
and suggests that a good approach to undertake when
approaching a project such as this one is “to combine what
the manufacturer suggests with what others have done in
the industry for a number of years.”
When approaching any project Cooke & Dowsett want to
know what type of soil classification is being constructed on.
“We look at the classification to see how much movement
we are dealing with. The measures we put in place are
dictated by the amount of movement. If you are faced with
a sloping site or with bad soil, be prepared for some to be
taken out, re-filled and compacted to 95%. Once that is
done, engineers will need to give another classification so
you are best to wait for that to come back before you start
designing.
“We clip drains running beneath the building every
600mm. We put a clip and a tie on and have found that most
effective and efficient.
“When backfilling the drain we don’t compact the soil
as per usual. It’s a loose fill. When the building moves the
pipe moves with it. The critical point is where it leaves the
building/footing, that’s where the expansion and swivel
joints come in as they allow for the movement.”
New products are continually being developed as
technology grows and manufacturers become more
advanced in their thinking, so it pays to keep your ear to the
ground with what’s on the horizon to make your job easier
and to ensure that drainage systems are ready to stand up
to the test that reactive soils can bring.
As you can see, the issue of reactive soils is not straight
forward and we would require many more pages to fully
cover the topic. While Mother Nature is highly unpredictable,
best building practices are not, so the next time you are
faced with a highly reactive site, be sure to consult the
standards and codes and work closely with the geotechnical
engineers and builders to ensure you construct plumbing
and drainage that will be compliant.
Further research by the likes of Swinburne University
into the effects of changing weather patterns and how
future building designs can better cope with such patterns
will hopefully lead to less impact on homes in the years to
come.