While Northland's long summers are enjoyed by most, they created ongoing challenges for Fonterra's Kauri plant, north of Whangarei, which is dependent on year-round supply of water for plant operations. To ensure access to this critical resource, Fonterra chose to invest in the construction of a large water lagoon.
United Civil Construction undertook construction of the lagoon, which is lined with polyethylene and has a surface area of over 60,000m2.
The project involved 200,000m3 of bulk earthworks. With the material proving to be very moisture sensitive and in some cases in a saturated state, a mixture of drying back and blending with imported material was required to meet the compaction requirements. Extensive erosion and sediment control measures, including flocculation within the large ponds, were constructed to treat runoff from the site.
Fonterra’s water pumping station was significantly upgraded, including their full electrical control systems. Additional pipe work was constructed linking the new lagoon to the existing lagoon and upgraded river pump station. This work was completed during the annual factory shutdown period to ensure minimal disruption to the Fonterra factory.
- The lagoon was constructed on farmland, home to large numbers of stock. United Civil Construction worked closely with farm management to ensure farming operations were not interrupted during the project.
- The works included the construction of deep subsoil drainage and a large toe drainage blanket beneath the lagoon embankment.
- Upgrades to the pump station were carried out under restricted timeframes, to ensure no disruption to the plant.
- Extensive erosion and sediment control measures were constructed and the performance of these were strictly monitored to mitigate the environmental impact of the works
- Ring fenced site, health and safety adapted to Fonterra’s permit to work system.
Raw water is now pumped to the lagoon during wetter periods, to ensure adequate water supply during the drier summers and droughts.
This major capital investment project was completed over two earthwork seasons.