Portaloos in use as septic tanks overflow
Some residents in North Canterbury are still grappling with the effects of last week's flooding, as groundwater channels brought to the surface continue to flow.
Septic tanks on about 50 Mandeville properties were overwhelmed by the record rainfall, leaving owners without a working sewer system.
Portaloos were distributed to the affected streets over the past week, Waimakariri District Council utilities manager Gerard Cleary said.
''If we keep getting rain into the foothills over winter, which we're likely to, it's quite likely we will have this as an ongoing issue this winter.''
Former Dallington red-zoners Pat and Nicky Bodger were forced to bring their chemical toilet out of storage when their septic tank overflowed.
They had moved into the property last July, and noticed water in a nearby swale begin to flow soon after.
However, last week it overflowed and water came within centimetres of their front door.
The couple had spent months in their badly damaged Dallington home after the earthquakes, coping with a broken sewer system and flooding caused by liquefaction.
They did not want to leave the riverside suburb, but had come to terms with the move to North Canterbury.
''We started to relax in December and something like this brings it all back,'' Pat Bodger said.
Cleary said increased maintenance of the drainage system would hopefully improve the situation.
''The main thing we can do is drain it away. We are looking for bottlenecks in the system.''
Some underground channels were known to the council, but others appeared to be new, Cleary said.
A six-strong team of contract engineers was being assembled to find and present solutions to the council in a few months.
The team would address historically vulnerable areas, including south Kaiapoi and areas affected by the resurgent underground water channels.
Flooding in west Kaiapoi would be most difficult - and expensive - to address.
The area was historically vulnerable to flooding, and may need a new pump station. However, this was not part of the council's earthquake recovery strategy for infrasturcture in the town.
Cleary attributed the flooding to exceptional levels of rainfall, rather than the impact of the earthquakes on the land.
''Last week we had 200 millimetres, and the average annual rainfall for the district is 550mm. So, we've had a third of annual rainfall in two days.''
Emergency repairs on roading damaged during the flooding had been completed, but Jacksons Rd Bridge in Ohoka needed to be replaced, council roading manager Ken Stevenson said.
The repair bill for roading damage was more than $300,000, with the bridge replacement estimated at $190,000.