The charge related to an incident on May 22 last year when a build-up of fumes were discharged into the air in the form of a 20-30m gas cloud.
The build-up was caused by a lack of communication during staff handovers about a change in process settings that prevented the gas from being properly extracted.
That led to the fumes bypassing the treatment system and drifting towards a street beyond the property boundary.
Those who were exposed to the gas cloud suffered temporary effects ranging from a metallic taste to difficulty breathing and two people were hospitalised. One of those hospitalised was exposed to the discharge while walking along the street.
Judge Kirkpatrick reflected on the preventive measures Ballance has since introduced.
“These really only serve to indicate what might have been done earlier to ensure that such discharges did not occur,” he said.
He considered two previous prosecutions relating to the plant for similar offences in 1999 and 2014 were aggravating factors.
Like the previous offences, the latest case involved shortcomings in Ballance’s operational and emergency processes and temporary health effects to people at and near the site.
Bay of Plenty Regional Council compliance manager Alex Miller said things like sulphur dioxide and fluoride can have significant effects on both the environment and human health so it’s critical commercial operations that generate contaminants are well managed.
“While this event was an accident, caused by a series of fundamental errors at the fertiliser plant, with a main road on one side and the Whareroa community behind on the other, the fact that more people were not affected was a matter of good fortune rather than good management.
“Unfortunately, we’ve undertaken prosecutions for similar offences at this site three times now, with the most recent in 2014.
“We hope that the measures which they’ve put in place after the offending mean that we don’t arrive here ever again,” he said.
Fertiliser is made at the plant by mixing finely ground phosphate rock with sulphuric acid, water and recycled scrubber liquor in a reaction vessel.
The mixture is solidified in an acidification den and a number of by-products are generated as a result, including gaseous fluoride and sulphur contaminants.
