The Ancient Mariner's plaint - water, water, everywhere - has rung out across Auckland this year.First came the city's dirty secret of wastewater and raw sewage flowing into the Waitemata Harbour almost every time it rains. In the past week, three rain bombs overwhelmed the main water treatment plant with silt and devastated homes and businesses in West Auckland. Here's a lookat the water problem confronting Auckland.
How does the city's water system work?
Auckland gets water from the Hunua Ranges, Waitakere dams and the Waikato River. Most water is treated at the Ardmore, Huia and Waitakere treatment plants. Watercare Services, a council-owned business, provides water to homes and businesses. It also takes wastewater, sometimes mixed with stormwater, to plants at Mangere, Rosedale and other smaller plants for treatment before being discharged into the sea. The Auckland Council is in charge of stormwater.
Why is sewage flowing into the Waitemata Harbour in 2017?
Many of the pipes in the older parts of the city were installed 100 years ago when stormwater and wastewater were combined. Many of these pipes have not been replaced or "separated". In January, the Herald revealed waste flows from 41 points around the inner-city suburbs almost every time it rains. One million cubic metres of waste and raw sewage is pouring into the harbour each year.
What is being done to fix the wastewater problem?
Watercare has a $1.7 billion plan to build new "interceptor" pipes and feeder sewers that will reduce wet-weather overflows from the area by 91 per cent by 2035. Mayor Phil Goff has asked for work to be done by June 30 on bringing forward work to invest in clean and safe beaches, but has said it will come at a cost to ratepayers.
The past week saw a one-in-a-100-year deluge. What happened?
The power-packed storm that meteorologists dubbed the "Tasman Tempest" delivered Auckland more rain than typically falls for the whole of March. It was likened to a "weather traffic jam", not unlike an Auckland morning during March Madness, by Niwa meteorologist Ben Noll. It was an autumn trifecta of strong and slowing-moving low pressure, deep tropical moisture, and a blocking ridge of high pressure to the south. The storms left water-flooded fields, raging rivers and closed roads in Coromandel, Clevedon and other rural areas, left the Ardmore treatment plant struggling to cope with silt and wiped out homes, businesses and a sinkhole in New Lynn.