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Proposed conditions for keeping bird numbers down at Smooth Hill could present a huge risk to the landfill planned for the site south of Dunedin, an environmental consultant says.
Due to the proposed site’s proximity to Dunedin Airport, about 4.5km away, draft consent conditions for the Dunedin City Council application call for numbers of some species to be kept to zero on site daily.
If this was not achieved over three consecutive days, the landfill would have to stop operating until the birds were not present for five consecutive days, the condition says.
The potential for the landfill to attract birds and create safety issues at the airport was a major factor when a regional council consultant last month recommended the city council’s landfill application be refused.
Now, Environmental Consultants Otago principal and senior environmental planner Ciaran Keogh said the natural curiosity of Dunedin’s abundant black-backed gulls could lead to long closures of the proposed landfill, creating problems for the city’s domestic waste disposal.
At Nash & Ross’s nearby Kaikorai Valley Rd landfill — where food waste was not accepted — there could still be several black-backed gulls a day, Mr Keogh said.
And landfill operations could not simply stop and restart, he said.
"There’s a whole raft of difficulties.
"These are things that need to be operating without interruption.
"It is a huge risk.
"And it’s just like any other piece of urban infrastructure — when it stops working it has a chain reaction effect through all sorts of things.
"Having waste mount up in facilities that are designed to handle daily throughput would become difficult to manage rapidly," he said.
The Smooth Hill site is home to up to 14 native and eight exotic bird species.
The regional council’s draft consent condition requires bird species 50gm or more to be kept to zero, which would include birds the size of a starling and above.
However, male black-backed gulls weigh more than 1kg and females about 850g, and the gulls are considered the species most attracted to organic waste in landfills.
When asked whether the draft condition of "zero" was realistically achievable or potentially disruptive to landfill operations, a city council spokesman said because the consent application was in a statutory process, the council was unable to comment.
However, the council’s application does address a range of management plans for birds to mitigate the risk of bird strike at the airport, including hiring a "bird control officer" and reducing organic waste from entering the landfill.
It said the landfill would employ staff or contractors to disperse birds from the tip face during daylight operating hours until an end-of-day cover was applied.
These dispersal methods would include using "stock whips, pyrotechnics, starters pistols and portable distress callers".
If they did not work, shooting and poisoning would be next.
Further, the application noted at least 3000 black-backed gulls fed at the Green Island Landfill, which is proposed for closure in the next few years.
These birds would seek an alternative food source when the Green Island Landfill closed and could be attracted to Smooth Hill if food was readily available and accessible, the application said.
Public hearings about whether the proposed landfill should be granted consent are to be held in about two weeks.
Aviation safety is not the only concern.
The city council’s application was publicly notified in September last year. A total of 283 submissions were received: two in support, nine neutral and the rest opposed.