Heavy rain forecast for Taupō today is expected to hamper recovery efforts following the major wastewater spill to the lake on Tuesday, and could increase the risk of more wastewater entering the lake.
The Metservice is warning the district to expect between 60 to 80mm of rain to accumulate between 9am and 4pm today with peak intensities of 25 to 35mm/hr.
The water main broke on Tuesday just after 2pm causing a large washout on the lakefront. About an hour later the footpath collapsed and took out a wastewater pipe causing around 800,000 litres of wastewater to enter the lake.
Yesterday the community was warned it could take three to five days until wastewater flows could return to normal. However today after updates the repair timeframe, a week was now looking more realistic, chief executive Gareth Green said.
Today, the forecast rain was the biggest concern. While some of the largest pumps in the country had been brought in to help manage wastewater flows at the site of the break, to reduce the likelihood of any more entering the lake, the site was now at pumping capacity, Mr Green said.
“With the forecast heavy rain, it is even more critical that our community tries to minimise water use as much as possible. It is probably more important today given the weather is something that is completely out of our control.”
It was typical for rain water to increase flows in the wastewater system as it could enter through a number of ways including gully traps and leaks around manholes.
About two thirds of the Taupō township contributed to the wastewater flow to the broken pipe. Peak times were between 6am and 9am and 3pm and 9pm.
While Acacia Bay and Nukuhau were not affected in terms of wastewater, Nukuhau residents were still being urged to limit their water use while repairs were made to the water connection.
The supply to Nukuhau was restored quickly on Tuesday afternoon with a temporary repair but there was likely to be some pressure fluctuations until a more permanent repair was made as there was limited flow. Pumps at the Nukuhau pump station burnt out when they ran dry on Tuesday and new ones were on order and were expected to arrive in the next couple of days.
Health warning signage had been installed at the site of the break and along the route of the plume, including along the Waikato River. They would remain in place until water sampling showed Ecoli results were within recreational health guidelines. Water sampling was being undertaken twice a day.
Drinking water across the district was not affected and monitoring had been increased to ensure early detection if there was further wastewater spills into the lake.
Tongariro Street and Lake Terrace is still closed between Heuheu and Titiraupenga Streets and detours are in place.
Investigations into the cause of the breaks were continuing.
Regular updates will be available on the council’s website and Facebook page.