The cost of maintaining
a navigable entrance depends on site specific data, including sand properties,
availability of electrical power, geotechnical information, annual quantities of sand to
be bypassed (transferred), initial quantity of dredging to rectify current condition,
length of contract and type of contract.
In a typical fixed installation, the Sand Shifter unit is buried within the sand
accumulation to create a sand trap that captures the passage of sand. A Sand Shifter unit,
in combination with a jet pump, recovers the trapped sand. The sand is discharged to an
onshore pumping station where the sand/water mixture is pumped through a transfer pipeline
to discharge clear of the entrance. If required, the discharge point is readily
relocatable for beach nourishment.
Slurry System Sand Shifter
A mobile Sand Shifter unit may be used initially to remove accretions of sand that have
moved past the Sand Shifter unit prior to installation of the fixed system. Once the fixed
system is installed there is no ongoing requirement to maintain a mobile system.
The Sand Shifter units are self burying and do not require an expensive supporting
pier. The buried units are protected from storms and do not obstruct navigation, public
access or interrupt the aesthetic lines of the beach. Installing the Sand Shifter units in
a shore parallel configuration maximises sand transport onto the units through the
onshore-offshore movement of sand through wave action. The shore parallel configuration is
readily accessible for installation and maintenance by shore based plant. The Submarine
Sand Shifter units are designed for long life with polyurethane linings on high wear
components.
The Sand Shifter unit system is fully automated and operated on an 'as required' basis,
dictated by the littoral transport rate. During storm activity, with increased littoral
transport rates (greater than 100 cu.m/hr), the system will operate continuously. The
excess littoral sand not bypassed in the storm period, is trapped within the buffer zone
and fed back to the Sand Shifter units for transfer by normal wave action after the storm
activity
