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Published: 2008-06-03 00:00:00

Dairy processor Open Country Cheese (OCC) is being allowed to spread more wastewater irrigation on to farmland near its Waharoa plant, provided it complies with conditions aimed at managing potential odour problems and minimising extra nitrogen leaching.

The new resource consent from an Environment Waikato hearings committee will allow OCC, one of the largest employers in the Matamata district, to process up to two million litres of milk per day.

The potential for more odour and nitrogen run-off were the two key issues considered by the committee during a12 May hearing over the resource consent application to carry out more wastewater irrigation.

In granting the application, the committee said it was confident the risk of offensive odour was low, provided the company used best practice to operate its wastewater treatment and irrigation systems.

While there had been a history of offensive odour issues at the dairy factory site, the company had carried out significant upgrades to address the problem.

The committee carried out a site visit to look at the upgrades and was satisfied the company had taken steps to sufficiently control odour.

It noted the majority of neighbours were located to the east of SH27, with “generous buffer distances between neighbours’ houses and the proposed irrigation”.

The committee also imposed a condition that the company must hold public meetings twice a year where any concerns about odour or other issues could be discussed.

Meanwhile, the company applied to increase the nitrogen load on wastewater treated paddocks from up to 150 kilograms of nitrogen per hectare per year to up to 300 kilograms of nitrogen per hectare per year.

The committee was satisfied that the extra nitrogen loading would not have any significant adverse environmental impacts provided consent conditions were complied with.

Enviroment Waikato resource officer Barry Campbell said nitrogen in dairy factory wastewater does not leach into groundwater or waterways in the same way that nitrogen in urea fertiliser used by farmers does.

OCC was to apply the wastewater in comparatively small, regular amounts so that it could be absorbed by soil rather than leach to waterways. Another consent condition was that there would be minimum periods between wastewater applications to help ensure the nitrogen was able to be taken up by soil.

Although there was potential for a small increase in the amount of nitrogen entering groundwater from the paddocks, groundwater nitrate concentrations would remain comfortably below the New Zealand drinking water standard, the committee’s decision said.

The committee imposed a condition that will require the company to regularly monitor nitrate levels in groundwater and provide reports to Environment Waikato to ensure that activity remains sustainable.

“The likely effects are known with a high level of certainty, and we are confident that the proposed irrigation will be sustainable over the term of the consent,” the committee said in its report.