page_title: Hamilton, New Zealand
section_title: Sewage
hierarchical_section_title: Hamilton, New Zealand / Utilities / Sewage
caption_attribution_description: English: prestressed concrete box girder bridge over Kirikiriroa Stream at Tauhara Gully
context_page_description: Hamilton is a city in the North Island of New Zealand. It is the seat and most populous city of the Waikato region, with a territorial population of 169,300, the country's fourth most-populous city. Encompassing a land area of about 110 km² on the banks of the Waikato River, Hamilton is part of the wider Hamilton Urban Area, which also encompasses the nearby towns of Ngāruawāhia, Te Awamutu and Cambridge.
  The area now covered by the city was originally the site of several Māori villages, including Kirikiriroa, from which the city takes its Māori name. By the time English settlers arrived, most of these villages, which sat beside the Waikato River, were abandoned as a result of the Invasion of Waikato and land-confiscation by the Crown.
  Initially an agricultural service centre, Hamilton now has a diverse economy and is the third fastest growing urban area in New Zealand, behind Pukekohe and Auckland. Hamilton Gardens is the region's most popular tourist attraction. Education and research and development play an important part in Hamilton's economy, as the city is home to approximately 40,000 tertiary students and 1,000 PhD-qualified scientists.
context_section_description: Sewage long lagged behind other utilities. Initially sections were large enough for septic tanks to work as well as they could in peatlands, but it wasn't long before the 1882 drainage scheme was used for sewage connections. By 1904 complaints were being made about the blocked insanitary drain between Victoria and Anglesea Streets, resulting in a faltering start on a night soil service. The 1907 referendum, which approved purchase of the gasworks also agreed to raise a loan for sewage pipes (though rejected a plan for a steam tram). In 1917 Mayor Ellis rejected the Health Minister's suggestion, saying it was impossible to afford a sewage farm. By 1919 only about a third of the city had sewers, but between 1923 and 1925 "considerable progress" was made and sewage reticulation was further extended in 1933. However, there was a sewage related epidemic in Melville in 1940 and Melville, Fairfield and Hillcrest were added to the sewer network from 1949. Although by 1956 80% of Hamilton had sewage pipes, it was only piped to 14 septic tanks (17 when replaced in 1976), which were emptied several times a year, either into the Waitawhirwhiri Stream, or directly into the Waikato. In 1956 the Pollution Advisory Council said, "the daily flow of sewage effluent and trade wastes from Hamilton City is three million gallons… in effect, partly digested sludge and raw sewage is being disposed of into the Waikato River". Downstream from Hamilton contaminants increased 10 times between the 1950s and the early 1970s. The 1953 Water Pollution Act set up a Pollution Advisory Council, but it had no control powers until 1963.
  In 1964 the Department of Health ordered adequate treatment for the sewage. Steven and Fitzmaurice, Consulting Engineers, presented a plan to Council early in 1966. There was some work on piping new areas in 1966, but work on the major trunks and interceptors didn't start until 1969 and building at Pukete sewage works started in January 1972. The first sewage was treated in July 1975 and was fully connected early in 1977.
  The trunk lines needed a 165-metre-long (541 ft) bridge, about 14 m (46 ft) above the Waikato, another prestressed concrete box girder bridge over Kirikiriroa Stream at Tauhara Gully and 2 steel pipe bridges over other gullies. The River bridge was designed by Murray-North Partners and the others by council engineers.
  The Pukete sewage works cost $12.5m ($160m at 2015 prices). It now cleans 40 million litres (11,000,000 US gal)/day, which is aerated for about 2 hours in a sedimentation tank, disinfected with chlorine, dechlorinated with sulphur dioxide and discharged into the Waikato through a diffuser outfall on the river bed.
  CH2M Beca, successor to the previous engineers, upgraded the plant from 1998 to 2002 to improve nitrogen, BOD and suspended solids levels, with a change from chlorination to UV treatment and biogas and natural gas 1.5 million watts (2,000 hp) cogeneration units, able to power the treatment processes and export surplus to the grid.
  A further 5 year upgrade started about 2009 expanding and improving the plant, including phosphorus removal.
  Despite the improvements there have been on-going problems. In 2012 the council was prosecuted for a sewage sludge spill and consent conditions were breached in 2013 due to a bacterial problem. In 2014 up to 800 m³ (180,000 imp gal) of untreated sewage got into the river.
  There are also problems with pumping stations. Out of over 130, up to 20 fail each month.
caption: Prestressed concrete box girder bridge over Kirikiriroa Stream at Tauhara Gully. Photo 2015.
exif: {"Image ImageDescription": "", "Image Make": "Canon", "Image Model": "Canon PowerShot SX240 HS", "Image Orientation": "Horizontal (normal)", "Image XResolution": "72", "Image YResolution": "72", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Photos 1.0.1", "Image DateTime": "2015:09:16 10:53:33", "Image ExifOffset": "248", "EXIF ExposureTime": "1/640", "EXIF FNumber": "4", "EXIF ISOSpeedRatings": "200", "EXIF SensitivityType": "Standard Output Sensitivity and Recommended Exposure Index", "EXIF ExifVersion": "0230", "EXIF DateTimeOriginal": "2015:09:16 10:53:33", "EXIF DateTimeDigitized": "2015:09:16 10:53:33", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "3", "EXIF ShutterSpeedValue": "149/16", "EXIF ApertureValue": "4", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "29/8", "EXIF MeteringMode": "Pattern", "EXIF Flash": "Flash did not fire, compulsory flash mode", "EXIF FocalLength": "9/2", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "2818", "EXIF ExifImageLength": "1369", "EXIF FocalPlaneXResolution": "1000000/61", "EXIF FocalPlaneYResolution": "1000000/61", "EXIF FocalPlaneResolutionUnit": "2", "EXIF SensingMethod": "One-chip color area", "EXIF FileSource": "Digital Camera", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF DigitalZoomRatio": "1", "EXIF SceneCaptureType": "Standard"}