In 2000, the Whangarei District Council (WDC) embarked on a programme to extend the district's sewer reticulation network around Whangarei Harbour, to improve water quality in the city's harbour - a popular spot for recreation and food gathering.
The physical works extended along the northern shoreline of the harbour, from Waikaraka to Urquharts Bay near the harbour entrance, where the septic tank systems in use were often failing to treat sewage to an acceptable standard. In late 2008, United Civil Construction completed the third stage of this sewerage reticulation scheme, a $14.4 million development, which won a New Zealand Contractors Federation Construction Excellence Award in 2009.
- The extensive use of alternative construction methods, and in particular directional drilling, to install pipeline so as to minimise disruption to landowners.
- The construction of wet wells and emergency storage facilities (up to 8m below water level) immediately adjacent to an environmental sensitive coastal marine area.
- The construction of pipelines in areas of high archaeological importance and cultural significance.
- Winner of the New Zealand Contractors Federation 2009 Construction Awards (for projects with a value between $5 million and $20 million).
- The works were located in a coastal urban environment and often in areas where the topography and underlying soil conditions were not conducive to the easy installation of pipelines and pump stations. In particular, the hard underlying basalt rock often made the excavation of trenches a difficult and time consuming exercise.
Completed over a period of two years, the scope of this project included the construction of the following;
- 15 pumping stations and associated emergency storage facilities, electrical control and telemetry systems
- 23,000m of pressure pipeline using polyethylene pipe of diameters up to 280mm
- 13,500m of gravity pipelines
- 230 manholes
- Individual connection to 476 properties
- Miscellaneous associated works including landscaping, retaining structures and pipe bridges.
In addition to this third stage, United Civil also undertook construction work on the previously completed first and second stages of the overall scheme, which has provided significant public health benefits to our community and all others who experience the beauty and amenity of the Whangarei Harbour.