Ammonia breaches consent

Spikes in ammonia gas levels inside the paper mill building at Mataura, where ouvea premix is being stored, often breach levels allowed under resource consent conditions.

On one day in November last year, levels peaked at more than six times what was allowed, due to high temperatures in the town.

Monitoring reports show that spikes in the gas levels recorded inside and outside the building often breach the five parts per million limit allowed under a retrospective consent, although the monthly averages were usually lower.

Gore District Council chief executive Steve Parry said the levels of gas recorded at the site were not hazardous, and were affected by temperatures inside the building.

He said ammonia gas needed to be recorded at 25 parts per million before it was injurious to human health.

‘‘There are spikes which are always driven by temperature, they are higher in summer and lower in June, July and August.

‘‘The reports from the independent company that is monitoring it for us verify that.’’

In March 2017, two sensors were installed to compare the indoor and outdoor ammonia levels.

The gas has been monitored by Land and Water Science since April 2018.

Measurements are recorded continuously and reported as a five-minute average of both the outdoor and indoor sensor.

The company sends the council a monthly report about the ammonia levels.

In every month of 2019, the maximum ammonia concentration for both sensors exceeded the consented amount of five parts per million on numerous occasions, except in June and July when only the outside monitors recorded breaches, the reports say.

In November 2019, the maximum concentration from the inside sensor was 34.3 parts per million – a spike recorded on a hot day, the reports say.

However, the average across each month was lower than five parts per million both inside and outside the building.

The Environmental Protection Authority says ammonia gas has a strong pungent smell at five parts per million.

WorkSafe’s acute workplace exposure standard for ammonia is 25 parts per million, or 17 milligrams per cubic metre. This value should not be exceeded over an eight-hour working day.

There is also a Short Term Exposure Limit for 15-minute periods of 35 ppm, or 24 milligrams per cubic metre.

Environment Southland general manager policy, planning and regulatory services Vin Smith said it was the regional council’s understanding that some low levels of ammonia had been detected in the mill at Mataura.

The district council was the authority responsible for monitoring consent conditions of the ouvea premix stored at the mill.

‘‘As the regional council we have responsibilities under the Resource Management Act in relation to discharges to air within the environment, but not for discharges within a storage facility.

‘‘Environment Southland is very concerned about the situation at Mataura and has been taking action for some time, working with local and central government to find a long-term solution for the removal of all dross stored within Southland.’’

The ouvea premix was first moved inside the building in 2014 by Taha Asia Pacific, which went into receivership in 2016.

The Environmental Protection Authority has classified ouvea premix as a skin irritant, eye irritant, and an aquatic eco-toxicant.

‘‘Environment Southland is very concerned about the situation at Mataura.’’ Vin Smith Environment Southland