Town’s big, smelly whoopee cushion
Nature works in mysterious and sometimes malodorous ways, as a Hawke’s Bay town is finding out.
Waipukurau created an anaerobic pond last year at its wastewater treatment plant.
It is entirely enclosed by a cover, to exclude oxygen and light so that nature can get to work to break down sewage biologically.
It’s working so well that a large, smelly bubble of gas built up, forcing Central Hawke’s Bay District Council to let some of it out this week.
That reduced the bubble to about a quarter of its size – but led some neighbours to complain about the smell. ‘‘Temporarily, until a final solution is implemented to control the gas, some odour may arise,’’ the council said this week.
The growth of the gas bubble was a sign that bacteria in the pond were working as they should, council chief executive Monique Davidson said. However, the pond’s built-in vents that allowed gas to escape had proven ineffective.
‘‘Over the past month, council has physically restrained growth of the gas pocket by further securing the pond cover and forcing gas out through vents. This is not a longterm, effective solution.’’
The bubble did not pose a health and safety risk; however, Davidson was concerned that, if it continued to grow, ‘‘in an extreme wind event, the cover could be torn from the pond’’.
‘‘This would cause significant and costly damage to infrastructure, and could cause potential harm to anyone on-site.’’
Industrial extraction fans would be manufactured and installed as a permanent solution but these would not be completed for about a month.
Next month, a project will be put to the council, proposing a solution for the Waipukurau and Waipawa plants.