Environmental Engineering Reference
In-Depth Information
h e fi rst plan was endorsed, thus imposing an extremely tight timeline—in
eff ect to plan, test, and execute the operation within just 7 months (Fig. 11.3).
h ere were seven components to the overall planning and implementation of the
aerial baiting campaign.
11.3.2.1 Legislative approval
Approval to aerially broadcast toxic ant bait in the Christmas Island National Park
was sought under the Environment Protection and Biodiversity Conservation Act
(1999). First, a Referral was submitted that outlined the extent of the invasion, its
documented and suspected impacts, and that aerial application of toxic bait was
the only effective method of control. A full environmental impact assessment of
the potential benefi t and risks was submitted (Green
et al
. 2002) and reviewed by
Environment Australia. The key conclusion was that the probable consequences
of not acting were far worse than the potential non-target impacts. The aerial bait-
ing operation was endorsed by Environment Australia (see
http://www.environ-
but the pace was such that offi cial approval was given while the helicopter and bait
were en route to Christmas Island.
11.3.2.2 The helicopter
It was necessary to source a civilian contractor with an appropriate aircraft, suitable
delivery technology, and experience to fulfi l the operational requirements of the
baiting programme. In March 2002, pilots from two helicopter companies were
bought to Christmas Island to reconnoitre potential loading sites and local fl ying
conditions, especially the hazards posed by seabirds. The successful tenderer had
previous experience of aerial baiting as part of the eradication programme for the
red imported fi re ant in Brisbane. They used a Bell 47 Soloy helicopter, which was
partially dismantled for shipment to the island, and reassembled at the Christmas
Island airport (Fig. 11.2b).
h e accurate treatment of YCA supercolonies presented special challenges for
the pilot, because boundaries were irregular, many supercolonies were relatively
small, and most lay within continuous forest and were not identifi able from above
the rainforest canopy. h e pilot developed a new system of precision navigation
to deal with these challenges, involving the use of two independent GPS units—a
highly accurate (sub-metre) Trimble diff erential GPS unit to stay on track as each
run was fl own and a hand-held Garmin GPS unit to delineate supercolony bound-
aries at the start and end of each run. Great skill was required as the pilot was fl ying
the aircraft at around 100 km/hour, while simultaneously keeping track of the
aircraft's instrument panel, the two GPS units, and seabirds.
Quality control was an important consideration when choosing the successful
tender. An on-board diff erential GPS recorded the exact routes fl own while the
bait stream was switched on. Once downloaded to the CIGIS, and buff ered to a
width of 12 m (the width over which bait was dispersed on each run), these records
