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MARCH 2011

In March 2011, the Kawakawa Bay Sewerage Scheme, NZ's first combination of vacuum collection sewer system and biological nutrient removal MBR sewage treatment plant was successfully commissioned by the designer of the scheme, Harrison Grierson.

The community of Kawakawa Bay, near Auckland, was established some 70 years ago as a traditional Kiwi bach community and by 2010 had grown to a population of approximately 600 people. Summer peak population figures can reach up to 2000. Until the new sewerage scheme was commissioned, domestic sewage was treated on individual lots by septic tank and irrigation line systems. Evidence of untreated sewage from poorly performing systems was found at the foreshore and in stormwater drains around the village which lead to the implementation of the sewerage scheme by the Council.

The new sewerage scheme is very environmentally friendly, the vacuum (the negative pressure in the pipelines) ensures that sewage is unable to leak from the collection system and after being conveyed to the treatment plant is treated to a very high level where nutrients are removed and the treated effluent is completely disinfected. The Kawakawa Bay environment is now being restored to its former pristine condition and can be better enjoyed by the resident and visitor population.