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Irrigation trial .. A kanuka stand similar to this will be part of a trial near Hanmer Springs to determine how natives perform under irrigation using wastewaster derived from sewage. PHOTO: FILE

By ROBYN BRISTOW

Planting pines on land bought by the Hurunui District Council in Hanmer Springs, where it intends to spray treated sewage and wastewater for irrigation, has some residents bristling.

Residents say it is a great opportunity for the council to plant natives on the 50-hectare block at the corner of River Road and Leslie Pass Road.

However, the council’s chief operations officer, Dan Harris, says the decision to plant radiata pines for nutrient management was based on available science when land options were considered during the resource consent stage.

There were also significant differences in operating costs between exotic plantation forestry and other options.

However, he says residents’ opposition to the pines has been taken on board and the council will use a seven-hectare block of kanuka on the land as a test area to gather information on how natives perform under irrigation.

This could lead to natives being planted when the pines are harvested.

Mr Harris says a study is needed to understand why the kanuka stand is thriving in the area, being the only stand of its type on that side of the Hanmer Springs basin.

One resident said on a local Facebook page that the block provided a wonderful opportunity to plant native trees and create a bird sanctuary. Deer were excluded because of deer fencing, while other pests could be trapped to ensure it was predator-free.

“Unfortunately, the council has decided to plant pine trees. The large amount of water will ensure these trees will grow so fast they will need to be harvested every 15 years, to prevent toppling due to wind, but will be too weak to be used for building, and will probably blow over earlier.

“A qualified ecologist has offered his services free-of-charge to design a planting and nutrient-uptake plan, but the council has refused.

“Pine trees should be planted around the boundary as they would grow quickly and not require watering, and would protect the young natives growing inside from the wind,” the Facebook post says.

Environmental reports suggest that, left unplanted and appropriately maintained, the heavily modified regrowth of kanuka would respond well to watering, Mr Harris says.

He says the council is committed to not only undertaking restoration of the area, but also monitoring nutrient uptake by the kanuka using test bores to improve the science on native planting.

If successful, the large scale trial will support future applications for native plantings in wastewater disposal zones, and may lead to expansion of native plantings after rotation of the exotic planting at the Hanmer Springs site, he says.

At present, under an existing consent, Hanmer Springs sewage is treated, with the resulting wastewater discharged in the Chatterton River.

Work began in 2014-2015 to move to a land-based discharge for the town’s treated wastewater. Several options around Hanmer Springs were investigated by the council and community board. Eventually, the River Rd site was bought, consent sought, and granted.

“It has been a long journey, with initial investigations dating back to 2007, 2008, when we got an extension to our existing resource consent,” Mr Harris says.

“We are aiming to have it operating, all going well, by the end of September.”