Sewerage ‘alarm bells’ addressed

The alarm bells over NelsonTasman’s sewerage infrastructure fail safes have been ringing less loudly after a range of actions were put into place in the past year.

At a Nelson City Council infrastructure committee meeting last Thursday, councillors received the Nelson regional sewerage business unit’s (NRSBU) annual report for 2020/2021. While the report was first received at an NRSBU meeting in September, councillors were briefed on a range of improvements put into place over the preceding year.

NRSBU general manager Nathan Clarke said highlights of the year included the implementation of a water reuse facility, an ultra-filtration system that allowed for the recovery of about 500 cubic metres per day of wastewater for reuse.

He said work had also been done to address issues around climate adaption and mitigation – including storm defences being installed around pump stations.

However, the major talking point of the meeting was around the region’s emergency infrastructure for sewerage.

‘‘There were alarm bells when I joined 18 months ago,’’ Clarke said. These included issues around overflows during heavy rain events and a lack of emergency power supplies to the Bell Island sewage treatment plant.

‘‘One [issue] was the ability to convey waste from the Tasman District Council’s facilities and the Beach Rd pump station to the Bell Island plant,’’ Clarke said.

‘‘Our capacity was 387 litres per second and Tasman District Council discharged in rainfall significantly more than that.’’

Clarke said a programme of works to duplicate the pipelines from Richmond to Bell Island was expected to be complete by June 2023. Emergency generation had been purchased and was expected to be installed in two to three months. The resilience of power supply was also being improved.