LETTER: Sludge: The ‘cart’ has already bolted

Tuesday 1 June 2021 | Written by Supplied | Published in Letters to the Editor, Opinion

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LETTER: Sludge: The ‘cart’ has already bolted

"The PMU (Project Management Unit) have yet to substantiate claims of safety with peer-reviewed, long-term studies of the impacts of disposing of aluminium sludge to agricultural soils (let alone in the tropics)."

Dear Editor,

In response to GHD’s ad: ‘The real science behind PACl sludge’ (Cook Islands News, May 26).

False demand for PACl sludge seems to have been triggered by selective science and media comments from local personalities. However, the by product of the water treatment method is nutrient deficient, it is anti-fertiliser – it is not ‘salty potting mix’.

The PMU (Project Management Unit) have yet to substantiate claims of safety with peer-reviewed, long-term studies of the impacts of disposing of aluminium sludge to agricultural soils (let alone in the tropics).

Now offshore experts have been solicited to offer opinion on a method of disposal that is not practiced in New Zealand. As such, they are only able to provide theoretical reassurance.

Setting aside the increased cost to growers, managing the nutrient-deficiency of the sludge by the addition of synthetic phosphorus and trace minerals needs to be reconsidered.

Eutrophication is the degradation of water bodies due to an excess of nutrient, often resulting from synthetic fertiliser run-off. In Rarotonga surface contaminants move rapidly from sloping fields, to waterways, and then to the lagoon.

Surface flooding has now become almost routine. Encouraging the increased use of synthetic fertiliser is irresponsible when our lagoon is already in crisis.

Given that the ponds are at capacity – and that To Tatou Vai staff are clocking extra hours shunting sludge between intakes – the PMU are attempting to shut the stable door when the cart has already bolted.

Te Mato Vai waste has not been managed. GHD are simply attempting to transfer the burden of an insufficiently-localised treatment method to a naive and trusting populace.

Andy Kirkwood

Te Vai Ora Maori