Possible solution identified for water clarity issues
Media Release: Monday 28 November 2016
Possible long-term solution identified for water clarity issues at Foxton and Foxton Beach
There may be an end in sight to water clarity issues that some Foxton and Foxton Beach residents experience.
Horowhenua District Council’s Water and Waste Services Manager Paul Gaydon says that deeper bores may possibly be the long-term solution.
Currently, Council sources water for the Foxton and Foxton Beach town supplies from bores approximately 200 metres deep. However, that bore water has a high organic content and a high ammonia content, requiring a higher level of treatment and higher dose of chlorine to disinfect.
Mr Gaydon said of several options identified, he favoured investigating the potential of 400 metre-deep bores to reach “different aquifers with better-quality source water”.
“At the moment we’re taking water of lower quality and then having to do a higher level of treatment to make it acceptable, whereas we could have top quality water to start with.”
Mr Gaydon said there was no “instant miracle solution” to fix the current water clarity issues.
“The water clarity issues at Foxton and Foxton Beach have been a long-time problem, so we don’t want to provide just a short-term solution, or rush into something that may not work," he said.
"This is why we’ve done a lot of investigation work to truly understand the problem, look at all the options available, and then identify and implement the right solution to fix the problem once and for all. I think most people would think this is the prudent way to go.”
Water clarity issues were also due to manganese, a naturally-occurring groundwater mineral that had built-up on the water mains pipes, and that had been dissolving and subsequently discolouring the water.
In August the pH-level of the water in the supply was adjusted slightly to decrease its acidity and increase its alkalinity, helping stop the manganese building-up. In addition, the pipes were being flushed on a weekly basis to help remove the manganese.
“But this is only treating the symptoms and not the cause. However, all this work has helped get the pipes into pretty good condition actually; certainly a lot better than they were," Mr Gaydon said.
“Some residents will still experience water clarity issues at times as the manganese works its way out of the reticulation system. In some pockets the issue is worse, particularly after water mains flushing or high water demand from residents, while other areas experience no water clarity issues at all.”
Further exploratory work and testing would now be carried out to investigate the viability and cost estimates of 400 metre-deep bores for the Foxton and Foxton Beach water supplies, with findings reported back the Foxton Community Board early next year.
As an interim short-term measure, the Council was also looking at providing treated/filtered water from public water stations at Foxton and Foxton Beach, available for people to go and fill containers with crystal-clear drinking water. The locations of these drinking water stations was currently being considered.
There were two other options no longer being considered at this stage. One was treating the water with ozone, an extremely strong oxidant that will remove both ammonia and quickly oxidise the organics and manganese. This will allow the manganese to be removed by the water treatment process. The other option was SanAqua technology, which uses “hydro-chemical activation” to electronically-modify water behaviour, and the composition, structure and behaviour of non-hydrous contaminants.
Mr Gaydon said that the bores from which Council currently sourced the water for the Foxton and Foxton Beach supplies had been given "secure bore status" by Ministry of Health Drinking Water Assessors.
Despite some properties receiving water with a discoloured appearance at times, the water was completely safe to drink. To ensure this, the Foxton and Foxton Beach water supplies were also continuously monitored, with readings taken every few seconds, 24 hours per day, seven days per week using online instrumentation, at the treatment plants and throughout the reticulation systems.