Chlorine need could last years

Christchurch’s mayor is adamant the city’s water will be chlorinefree in a year despite a new report stating repairing the wells could take at least three.

The cost to secure the city’s water supply has skyrocketed from

$630,000 to more than $21.5 million as the Christchurch City Council looks at long-term options to prevent the Government from making chlorination mandatory.

The council decided in January to chlorinate the water for up to 12 months while it repaired 103 well heads which were found to be unsafe and vulnerable to pollution from dirty surface groundwater.

But a new council staff report details repair options that could take between three and six years to complete.

Mayor Lianne Dalziel said the council would do ‘‘whatever it takes’’ and ‘‘invest whatever was required’’ to get the chlorine out of the water supply, even if it meant pulling in people and resources from across the country to complete the well head work. ‘‘We want to make sure our pristine water supply remains chlorinefree into the future. We are not going to take our focus off that.

‘‘It will cost, but the chlorine will go.’’

Dalziel said staff had alerted councillors it could take more than

12 months, but they had been told to come back with options to meet the deadline.

The council has no money in its budget to pay for the work, so the council would have to review its entire capital programme to find a way. Increasing rates was not an option, Dalziel said.

About $34m was budgeted to renew wells during the next 10 years, but staff did not want the council to use this money because it would mean it could not replace

23 wells nearing the end of their life.

One of the repair options was to raise 81 well heads above the ground at a cost of $21.5m. This was considered the best long-term approach, but the report said it would take up to five and a half years to complete because only 15 to 20 well heads could be raised each year.

A second option recommended securing 76 well heads below the ground and raising five at a cost of

$10.5m. This option would take three years to complete, the report said.

An additional 16 shallow wells would also need to be either replaced with deeper secure wells, at a cost of $15m or be treated with an ultraviolet (UV) system, at a cost of $5m. It would take three to six years to drill 16 replacement wells or up to two years to install UV treatment.

Dalziel said the time frames in the report were based on business as usual and the council was not taking that approach.

Council city services general manager David Adamson said it was likely the council would adopt several options, including raising the well heads and installing UV treatment.

The Havelock North Drinking Water inquiry last year recommended the Government impose mandatory treatment of all water supplies across the country to prevent another outbreak similar to the one in the Hawke’s Bay town in August 2016 when 5500 people fell ill from drinking contaminated drinking water, 45 were hospitalised and three died.

The Government has yet to decide its response to the recommendations, but if it did impose mandatory treatment, the council hoped it would be granted an exemption. Council staff believed an exemption was only likely to happen if it could demonstrate a high standard of water supply infrastructure.

The council’s infrastructure, transport and environment committee meeting will discuss the report tomorrow, before making a recommendation to council.

Chlorination of the city’s water supply started on March 26 with Brooklands, Kainga and Spencerville.

The northwest zone, which supplies 80,000 people from Belfast to Yaldhurst including Riccarton and Addington, was chlorinated from Friday.

The largest central zone, which supplies 225,000 people in Spreydon, Cashmere, Papanui, Linwood, Aranui and New Brighton, would be the last to be treated. The whole supply would be chlorinated by the end of this month.

‘‘It will cost, but the chlorine will go.’’ Christchurch Mayor Lianne Dalziel