Air quality debated

If dust levels from a Tamahere quarry expansion fall within tolerance levels considered acceptable for humans, then they should be fine for horses.

That was the view of air pollution engineer Dr Terry Brady, on the second day of a hearing into an application by Porritt Quarry for a tenfold expansion in its sand mining operations at Hooker Rd.

The quarry borders Whakanui Stud, which fears disastrous economic effects of the expansion, and considered an increase in airborne dust to be a potential danger to some very valuable horses.

But Dr Brady, an applicant witness, said concerns raised in relation to the effects of dust on horses were based on the assumption there would be a significant deterioration in air quality, and he saw no evidence that was the case.

He said a meeting of experts from all camps ahead of the hearing agreed that New Zealand's air quality guidelines and standards were developed to protect the very young, very old, and infirm.

''They should also provide a similar level of protection for horses as well,'' he said.

Consultants for Whakanui Stud have suggested a 100m buffer be imposed between quarry operations and the stud.

But Mr Brady said that would effectively cut in half the sand resources which could be mined.

Stud dust concerns were no more than ''theoretical speculation'' and rather than distrust control procedures, Whakanui Stud would be better to rely upon the ''normal expectation'' that good site management practices would be adhered to.

''If this philosophy were extended to every industrial operation in New Zealand then there could be no reliance on expected compliance with consent conditions, and every discharge to air would need to be separated from its neighbours 'just in case' they did not comply with consent conditions.

''That would be a reasonable approach if it were impossible to comply with the consent conditions or to achieve a satisfactory level of control even with compliance.
''That is not the case here.''

Hearing chairman David Hill asked Dr Brady if he thought the presence of horses living outside in a paddock meant the site could be defined as a sensitive environment under Ministry for the Environment guidelines.   ''If there was a retirement home next door you would,'' Dr Brady replied.

He said the size of the area to be worked at any one time would be limited to one hectare, the same as at present, and the normal working of the quarry would not pose a dust problem.

At worst there would 66 hours a year when winds were strong enough to mobilise relatively coarse sand, but they were usually accompanied by rain, making dust generation extremely unlikely.
The hearing is continuing.

- © Fairfax NZ News