A third of Christchurch homes will be chlorine free when a new safety plan is approved

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By 2023 or 2024, new companies are expected to take over the provision of the three water services, including ownership of infrastructure assets such as pipes, pumping and treatment stations, and ponds.

Chloe Ranford / stuff

By 2023 or 2024, new companies are expected to take over the provision of the three water services, including ownership of infrastructure assets such as pipes, pumping and treatment stations, and ponds.

At least 45,000 Christchurch households – around a third of the city – could soon have clean, chlorine-free water if the Department of Health finalizes a new city council safety plan.

The rest of the city could join in by the end of the year as the city council says it will address the outstanding risks in 2021 and remove chlorine if they are addressed. The final work should be completed by December.

Christchurch’s drinking water was chlorinated in early 2018 to stave off potential contamination after an assessment of the city’s wells found some of them unsafe.

Since then, the council has poured millions of dollars into upgrading the city’s water infrastructure.

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Only one of the city’s nine water zones was completely chlorine-free – Brooklands / Kainga (supplies 475 households). The two pumping stations in the zone were upgraded to such an extent that they no longer needed chlorine.

Meanwhile, three other zones – Northwest, Parklands, and Rawhiti – have been able to remove chlorine from some but not all of their pumping stations.

The lack of chlorine at selected pumping stations meant that some city households were already receiving chlorine-free water, but the number varied between 26,000 and 39,000, depending on overall city demand.

If the Department of Health approves the water safety plan presented by Christchurch City Council, all pumping stations in the northwest, parklands and Rawhiti would be cleared of chlorine.

GEORGE BELONGS / STUFF

Christchurch City Council Chairman Karleen Edwards has apologized after a chlorination review of the city’s water supply failure. (Video first released in October 2018)

These three zones, along with Brooklands / Kainga, covered approximately 45,000 of the city’s 130,707 water connections.

The largest of the four water zones that were planned to be chlorine-free was northwest.

It included about 27,000 homes in suburbs such as Avonhead, Burnside, Harewood, Northwood, and Belfast.

The zone had 11 pumping stations and seven still had chlorine at varying levels (most chlorinated pumping stations now had less chlorine than in 2018).

The council’s water safety plan states that there are still two unacceptable risks in the city’s other five water zones.

Each marker represents a pumping station in Christchurch as of April 2021 - green markings indicate chlorine-free stations, while all other colors indicate stations with chlorine, with the exception of the gray markings which mean a station is out of service.  Blue markings indicate pumping stations where the chlorine dose is the lowest.

Christchurch City Council

Each marker represents a pumping station in Christchurch as of April 2021 – green markings indicate chlorine-free stations, while all other colors indicate stations with chlorine, with the exception of the gray markings which mean a station is out of service. Blue markings indicate pumping stations where the chlorine dose is the lowest.

These zones roughly include suburbs to the far west, south, and southeast, as well as areas such as Lyttelton, Governors Bay, and Diamond Harbor.

The two risks were contamination of the reservoir and insufficient backflow prevention.

Backwater can occur when pressure drops and water is drawn back from a property and potential contaminants back into the pipes of the drinking water supply network.

Council water chief Helen Beaumont said remedial work on several reservoirs is expected to be completed by December, while backflow preventer installation at high risk sites would be completed by the end of June.

Helen Beaumont, head of the Council for Three Waters and Waste, says work to modernize Christchurch's wellheads is almost complete.

JOHN KIRK-ANDERSON / stuff

Helen Beaumont, head of the Council for Three Waters and Waste, says work to modernize Christchurch’s wellheads is almost complete.

Chlorine could not be removed from the five water zones until both risks were addressed, even though the city’s well modernization program was almost complete.

“With the unacceptable risks associated with reservoirs and backwater removed, the chlorine can be removed from any water supply zone,” said Beaumont.

The council presented its water safety plan to the Ministry of Health in December after initially disclosing it Stuff it would do so in June. It wasn’t clear why there was a delay.

It was the council’s second attempt to sign the plan after it was not approved in January 2020.

Beaumont said she expected more questions from the ministry before making a final decision on signing the plan.

The ministry would soon transfer its powers over drinking water to a new national water regulator, which was still being established.

The new regulator, Taumata Arowai, had already said councils would be instructed to chlorinate drinking water – but they could request an exemption.

Christchurch City Council had publicly pushed back the nationwide chlorination plans and signaled its intention to apply for an exemption.



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