Soft water one component of securing water supply - 4/04/2011

“Since 2000 the council has been trying to find as much water volume as possible closer to the city to reduce risk with the water supply from the Kai Iwi bores,” Mayor Main said.

“In 2005 council started looking for additional water sources because of the high risk of the existing sources at Kai Iwi, which have failed a number of times since then.

“At that time the council also started to think about softening the water supply. Because we needed to look for more water volume, our programmes were intended to also look for water that had an added benefit and was softer than the Kai Iwi source.

“The more water we could find that was naturally soft, the less money we had to put into a softening plant, but the long term priority for council is the security of supply.”

The council began a drilling programme to find new water sources in 2006 and work began on the Abelard and Heloise bores at Westmere in 2007.

“With the Abelard and Heloise bores on line plus the Aramoho bore, we now have three medium volume bores that are remote from Kai Iwi and can provide up to 50% of the total water supply for Wanganui,” Mayor Main said.

“It’s important for our community to realise that the main reason for council undertaking this project is to ensure the future security of Wanganui’s water supply. The fact that we are also getting softer water is an additional benefit to that.

“This community's dual investment in both a secure and good quality water supply and meeting our sewage and wastewater commitments gives us the ability to promote these when attracting new residents and businesses.”

A water softening plant is currently being built at the Westmere reservoirs and is due for completion in July. It will treat water from the hard water bores at Kai Iwi to soften part of the flow and mix it back into the reservoir. This combined with the soft water bores will soften the entire city supply.

Mayor Main said that the costs reported by the Wanganui Chronicle (April 4) are incorrect. A sum of $560,000 was double counted and $420,000 for bore repairs was included in the Chronicle’s total of $3.2M. For the years 2009/10 and 2010/11, the water security and soft water project is estimated to cost $2.26M, which includes $1.2M for the treatment plant.

Infrastructure and Property Committee Chair Cr Ray Stevens said the future requirements of the water supply will be a key issue in the Council’s next 10-Year Plan.

“We will need to carefully consider our existing supply and future needs as part of that process,” Cr Stevens said.

“Kai Iwi has bores that potentially may need to be replaced in the next 10 years because of their age and condition. Those bores have been in operation for 40 years now and provide the bulk of the water supply to the city.

“We are no longer relying solely on Kai Iwi for the city supply but we do need to look at the implications of a major failure at Kai Iwi or any of the bulk water sources.”