Storm brewing over dust cloud

By John Cousins


Sunny Mount Maunganui is also dusty Mount Maunganui, with scientists backing residents and boaties forced to put up with a black grime.

And while science has identified what causes the dust and concluded it was not hazardous to health, it was little comfort to people who live and play around the northern end of Mount.

An investigation into complaints found the quantity of dust often reached levels where it became a regular visual nuisance in windy weather.

The amount of dust was linked to vehicle traffic and the port.

The issue reared its head when Warwick Murray was describing the work being done by the Bay of Plenty Regional Council to manage the Bay's natural resources.

His report to the Tauranga City Council sparked deputy mayor and Marine Parade resident David Stewart to say that the black dust had become more prevalent in the last seven years.

Councillor Bill Faulkner said the dust was a significant issue and the regional council was under-estimating its effects.

He said the quantity of dust that landed on boats moored in the Sulphur Point marina indicated a significant problem. "You would not want to be inhaling it."

An analysis of the marina dust showed that although it was dominated by lighter coloured coastal sediments, the dark dust comprised particles from tyre wear and engine combustion.

Mr Murray said the port was doing all it could to suppress the dust problem.

A regional council study published earlier this year highlighted that the dust was a combination of activities at the port and the rest of the Mount industrial area, the coastline and the high concentration of heavy traffic and cars - all focused into a narrow isthmus.

Councillor Stewart said afterwards he regularly wiped down his outdoor furniture and what came off was almost like soot. "Some days are worse than others."

He noticed the dust became more noticeable seven years ago, resulting in work to fully enclose the coal handling system at the port's coal shed.

However, the dark dust has continued, even though no coal was going through the shed. Mr Stewart suspected that emissions from ships' funnels were part of the problem, although the dust was never bad enough to affect clothes on lines.

Harbour Bridge Marina manager Tony Arnold said they had to wash their building every month to keep it clean.

He blamed most of the fumes on belching from ships, industrial emissions and road grime and car exhaust fumes. Routine dust monitoring at the Mount by the regional council identified two windy days between 2000 and 2010 when dust exceeded the "recommended nuisance level".

The council said that otherwise dust levels were "quite acceptable" for an urban area.

Thirty complaint-driven samples taken over the last six years were analysed and four were traced to the coal shed before improvements were made to the coal handling system.

Significant amounts of palm kernel dust were found in six samples, resulting in the port modifying its handling and storage practices. Wood and bark particles from the log trade was found in six samples, often in significant quantities.

"On-going sealing of log storage areas in and around the port and improved yard management will see reductions."

The rest of the complaint-driven samples were found to contain "typical urban dust" including soil and sand, tyre wear, engine combustion particles, pollens, man-made fibres, paint flakes, rust flakes and possible welding residues.

A special five-month field inspection showed that the most dust occurred at sites closest to the main port area.

Samples were also collected from six industrial stacks at the Mount to see if there was a link with the dust collected at monitoring sites.

Despite several of the stacks producing distinctive dust particles, the monitoring did not point to any single industrial operation but to a range of sources.

The 16 dust complaints at the Mount last year were an 11-year low. Smoke complaints were only two short of the high of 43 while the 46 smell complaints was about average.

- Bay of Plenty Times

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