Project:
Date:
Engineer:
Contractor:
Location:
Bundaberg Distilling Company - Flood Mitigation Works
August 2012
GHD Consulting Engineers
PGS Contracting Pty Ltd
Bundaberg, Queensland
Gabions and Reno™ Mattresses
During a massive flood event in 2011, the Bundaberg Rum
Distillery storage sheds on the side of the Burnett River were
compromised due to severe scouring. GHD Consulting
Engineers were engaged by the client to design a significant
structure to protect the embankment from future flood waters.
GHD requested design assistance from Geofabrics and a
combination of stepped Gabions and sloped Reno™
Mattresses were considered as being the most appropriate
form of protection. Gabions and Reno™ Mattresses have been
used for many years in riverbank protection applications due to
their inherent flexibility, permeability, long term durability,
ecological benefit and ability to be colonised by natural
vegetation.
The GHD plan elevation drawing of the curved structure
The Gabion revetment incorporated a 90 degree curved section
on the south eastern corner of the storage facility. The bend
proved to be a challenging installation detail for the contractor
so PGS’s director Peter Sergiacomi contacted Geofabrics for
information on best construction practice for curved Gabion
walls. Assistance was provided based on previous project
examples and model units to enable PGS to visualise what was
required.
A buried Gabion ‘anchor’ was incorporated in the design at the
top of the 1:1.5 slope. The Reno™ Mattresses were connected
to this Gabion to provide the necessary sliding resistance. GHD
saw definite merit in using the Maccaferri type ‘Castoro’ double
diaphragm Reno™ Mattress for this project based on the
superior confinement it provides compared to a single
diaphragm unit.
The tender documentation therefore stated that “Reno™
Mattresses shall be "Maccaferri Castoro" type manufactured
from double twisted, hexagonal woven wire mesh of nominal
60x80 mesh, with 2.4mm o/d frame wire and 2.0mm o/d mesh
wire, complete with diaphragms at 1m centres. Diaphragms
shall consist of two layers of mesh having the base of the
Mattress and the diaphragms manufactured from one
continuous mesh panel.
The excavated benches and stepped Gabion revetment
The Gabion and Reno™ Mattress combination structure
The Advantages of Maccaferri 'Castoro' Double Diaphragm Reno™
Mattresses Over Single Diaphragm Rock Mattresses:
1) The diaphragm positions do not have to be adjusted as their
alignment is perfectly straight.
2) The diaphragms do not have to be kept taut during the filling
operation with wire stays, boards etc. as the double diaphragm
ensures that they are self-supporting.
3) The double diaphragm produces a more rigid unit for easier
placement and rock filling on slopes. Stiffer diaphragms don't buckle
as easily as single diaphragms.
4) The base of the Castoro type Mattress does not require the packing
folds to be flattened out i.e. the diaphragms accommodate this.
5) Rockfill is retained more efficiently in the 2m x 1m .compartments
with the stiffer double diaphragms as possible rock movement is
reduced during high flow conditions.
6) There is no weak joint between the base and diaphragms as they
are manufactured from one continuous panel of mesh.
7) Where Mattresses have to be cut, the Castoro unit proves to be far
more economical than the single diaphragm type Mattress because
each segment will have side panels which would not be the case with
the single diaphragm type. With single diaphragm units, structural
integrity cannot be guaranteed when units are cut and pieces of mesh
are connected on site to make end panels.
8) Castoro units are also suited to pre-filling and placing by crane as
reinforcement bars can be inserted between the diaphragms to provide
pick up points.
Maccaferri double diaphragm type
‘Castoro’ Reno™ Mattress.
Single diaphragm rock mattress
supplied by others.
The Reno™ Mattresses underlain by bidim® geotextile. Note the confinement provided
by the stiff double diaphragms.