Work is needed to shore up three historic Canterbury dumps at risk of spilling their rubbish into the sea.
One, the former Bexley landfill site, is at risk of leaking waste into the Avon-Heathcote Estuary in a storm but Christchurch City councillors cannot agree how to secure it.
Council staff offered councillors two solutions, but were asked to come back with more information on a third option.
Several councillors wanted to push ahead with repairs, citing March’s Fox River landfill breach on the West Coast – which spread waste including asbestos and needles over thousands of hectares – as a warning to act.
Councillor Pauline Cotter said it was remiss of the council not to act now. “I’m not prepared to risk in having an environmental disaster on our very own doorstep, when we’ve had the warning from Fox River.”
Cr Mike Davidson said it was shocking and disappointing the council was delaying when it valued environmental wellbeing.
Over the last three months, the council assessed the 10 historic landfills most at risk from climate change and found three (including Bexley) needed work.
Gollans Bay landfill in Lyttelton needs repairs to the cap over the waste and Le Bons Bay landfill on Banks Peninsula is at risk of erosion from a nearby river. Council staff are working out remediation options.
Former dumps at Wainui, Akaroa, Okains Bay, Barrys Bay, Allandale, East Truscotts, and West Truscotts were found to be at no risk currently.
About 600 metres of foreshore needs to be repaired at the Bexley site, which was damaged as the land dropped by up to half a metre in the Christchurch earthquakes.
The dump operated from 1956 to 1984, taking household waste, demolition material, hospital waste, car bodies and manufacturing waste. In 1977, up to 180 tonnes was being dumped there per day.
Waste from the 1970s and 80s is slowly being exposed as the foreshore erodes.
Staff recommended containing the landfill by layering three sizes of rock 85 centimetres deep over the area. The two finer sizes would keep waste in and water out, while the large outer layer would provide protection from waves.
If this $1.5 million plan had been given the go ahead, staff thought the work could have been finished by October 2020.
Some maintenance would be needed after storms if the outer layer was moved, estimated at $15,000 a year over the 25 years it would last.
The council would have to delay other work so this could be funded. The other option is a one-off rates increase of 0.28 per cent.
A more permanent solution lasting 50 years was considered but not preferred due to its $3.4m cost. It would have a lower risk of failure.
This would have used mesh and more rock armouring, with a different shape along the length of the work area in response to how the waves struck that section of bank.
The council will need to find the funds to do any work, as only $150,000 per year is budgeted for maintaining old landfills. There is currently $240,000 in this fund, saved from earlier years.
Cr Phil Mauger called for staff to look at sheet piling (interlocking metal panels driven into the ground) as a solution that might be cheaper and have less maintenance costs. Council staff said there may be issues getting consent for that.
Cr Tim Scandrett said the council needed to look at options with lower maintenance costs.
Crs Cotter, Davidson, Melanie Coker, Anne Galloway, deputy mayor Andrew Turner and mayor Lianne Dalziel supported the $1.5m, rock layering option.
Crs Mauger, Scandrett, James Daniels, Jimmy Chen, Yani Johanson, Aaron Keown, and Jake McLellan were against it, calling for staff to do more work before they made a decision.
Crs Catherine Chu, Sam MacDonald and James Gough had already left the meeting.
There are 131 former landfills in the council’s region, of which 56 are owned by the council.
A nationwide project looking at which former landfills are at risk from climate change is under way. Tonkin and Taylor has come up with a way to measure risk, which will be used to assess landfills in Canterbury, the West Coast and Southland in 2020.
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