By Grant Miller
Extra efforts to stop birds flocking to a proposed landfill near Dunedin Airport may not be enough to allay fears of bird-strike on aircraft, the airport has warned.
Pilots are also concerned the proposed landfill puts travellers at risk. (file pic) Photo: RNZ / Alexander Robertson
Allowing the planned dump to be set up just 4.5km away would be a fundamental flaw that could not be overcome by proper management, the airport stated in its recently released submission about the controversial Smooth Hill landfill proposal.
"Too close is simply too close ... once bird populations establish, management will not eradicate them."
The 4.5km separation was 2km closer than the 6.5km buffer zone used in a 1992 site selection process and 8.5km closer than the 13km buffer recommended by international aviation guidance.
There was already a relatively high risk of bird strike at Dunedin, the airport stated.
"An aircraft colliding with just a single bird has the potential to cause significant damage.
"Large, high-flying flocking birds like black-backed gulls pose the highest risk and collision is potentially catastrophic."
Birds such as black-backed gulls pose the highest risk, the airport says. Photo: floraandfauna.co.nz
The airport submission noted "escalating mitigations" had been proposed and it characterised this as a concession of increased risk.
The airport did not accept any increased risk to its operation was acceptable.
It also suggested the planned closure of the Green Island landfill would mean a significant colony of black-backed gulls would lose their main food source and be on the lookout for another.
The airport's submission was one of 283 received by the Otago Regional Council about the Dunedin City Council's proposal.
Two supported the proposal, nine were neutral and the vast majority were opposed.
Pilots add their voice
The New Zealand Air Line Pilots' Association raised similar concerns to the airport.
The landfill could result in unnecessary danger to the travelling public, the association said.
"Any land use that has the potential to attract birds to the airport vicinity should be the subject of a study to determine the likelihood of bird strikes to aircraft using the airport."
Dunedin Airport had a bird hazard risk above the national average.
Deterrence methods, including shooting and poisoning, could prevent birds from nesting at the landfill site, but it was doubtful such measures could be completely successful in keeping them away.
Te Runanga o Otakou supported the city council's application and said mana whenua were involved in the site selection process.
Trucking waste to landfills outside Dunedin or the region was unacceptable to mana whenua. Thirty-two possible locations for a new landfill were assessed based on landform, ecology, economic viability and social factors, and the Smooth Hill site was deemed the most suitable, the runanga said.
The Saddle Hill Community Board raised concerns about the quality of the city council's community consultation.
It would also be cruel to attract birds to a site near the airport and then kill them, the board said.
Some submitters were worried about possible pollution of waterways near the proposed landfill.
The Brighton Surf Life Saving Club said it was unacceptable the beach and creeks in the area could be put at risk of environmental problems.
Otokia Creek and Marsh Habitat Trust members said it was concerned the effects of wetland reclamation had been underestimated and the risk of leachate inadequately assessed.
This story first appeared in the Otago Daily Times