The Battle Of Waterloo

Annual Conference

Is, or was, your bore water considered ‘secure’? Until December 2016, the bores drawing water sourced from the Waiwhetu aquifer were.

A positive E.coli result was returned from water sampled at the Colin Grove bore around two weeks after the Kaikoura earthquake and subsequent heavy rainfall events. This was the first positive E.coli result returned from water sampled at the bores along Knights Road in Lower Hutt in over 30 years of operation. The bores met bore water security criteria as set out in the Drinking Water Standards for New Zealand 2005 (Revised 2008). Was this a ‘one-off’ result? A contaminated sample? Associated with the earthquake? Or potentially another Havelock North?

The Wellington region is supplied with water from three main sources, the Hutt river at Kaitoke, the combined flow from the Wainuiomata and Orongorongo rivers, and the Waiwhetu aquifer. The latter is a particularly important source, often providing up to 70% of the region’s drinking water during summer. Eight supply bores drawing from the aquifer were installed along Knights Road in Lower Hutt between 1980 and 1989.

In the months following the initial positive E.coli result, a further two positive E.coli results were obtained from samples taken from the supply associated with the aquifer. These results required a cross organisational response.

This paper summarises the events leading up to and following the identification of contamination in water sourced from the Waiwhetu aquifer, the water quality challenges faced by Wellington Water during this time, the national context following the Havelock North contamination incident, our approach, and decision making challenges including political and public opposition to chlorination. These were overcome and ultimately work led to permanent chlorination of the Lower Hutt water supply and the fast track installation of UV treatment at the Waterloo Water Treatment Plant.

Conference Papers

THE BATTLE OF WATERLOO.pdf

pdf
1 MB
26 Sep 2018