Fonterra Pahiatua Dairy Factory Expansion




Pahiatua, New Zealand

Completion date


Fonterra sought to expand their existing Pahiatua dairy factory by adding a large third milk powder dryer and associated dry store to triple the milk powder processing capability of the site. The increased expansion also required the construction of a new wastewater treatment plant nearby.

Our Brief

We were involved throughout the project from the initial design, through consent hearings, construction and the commissioning stage. Our role included assessing existing noise emissions prior to upgrade, building a detailed noise model of the site, and providing noise control advice for both existing and new noise sources. Critically, as the existing site was using 100% of its consented noise limit, we had to ensure that existing noise emissions were reduced sufficiently to allow the addition of the new dryer, boiler and expanded dry store. We were also responsible for preparing an assessment of the potential environmental noise effects resulting from the expansion for resource consent purposes. Noise measurements were undertaken during and after construction to verify that our noise control measures were successful.

Our design included treating a number of existing noise sources on site, such as the dryer air intakes and discharges, with a particular regard for reducing the presence of tonality. Other noise control measures such as solid timber fences for traffic noise control were used in the design.


The key challenges for this project were that the existing site did not comply with its noise limits, and the audibility of unpleasant tonality at neighbouring dwellings. Both of these challenges were overcome by significantly reducing noise emissions from a number of the key noise sources to eliminate the tonality, and ensure that the site would comply with the relevant noise limits upon the completion of the expansion.

By utilising our previous experience on other dairy related projects, we were able to build accurate noise models of both the existing site and the proposed expansion. These models were particularly useful for consenting the expansion and determining cost-effective noise control strategies. The models also enabled us to quickly assess various noise control and layout scenarios.

Commissioning measurements confirm that cumulative noise from the expanded site achieves its environmental noise limits and no longer exhibits tonality.


The site now complies with the relevant environmental noise standards, whilst being able to process three times the amount of milk powder. Even neighbours previously unhappy with the site now acknowledge that it is significantly quieter.

Noise emissions from the Pahiatua site reduced to a complying level and the tonality was eliminated.