28 | Fulton Hogan - Southland: Stead Street Pump station T T Russell Fredric Pump station upgrade one for the ages Fulton Hogan has been fully focused on achieving a great outcome for Environment Southland and Invercargill City Council. REGIONAL DEVELOPMENT SPECIALISING IN CONCRETE 027 3748 361 www.wagenerconstruct ion.co.nz THWAITESCONTRACTING Luke 021 204 3788 luke@thwaitescontracting.co.nz SPECIALIST IN: FarmDrainage • E luent Ponds • Dairy Lanes • General Earthworks HELPING TO KEEP NEW ZEALAND WORKING OneStaff’s national network of branches and industry specialist recruiters ensure you have access to a trusted partner to work with you in creating the ideal recruitment solutions. 0800 178 233 (1STAFF) The ancient Greek mathematician, physicist, engineer and inventor Archimedes would have to be seriously impressed with one of Fulton Hogan Civil’s latest projects. Fulton Hogan’s contract that relates to his genius involves replacing the Stead Street pump station alongside the Invercargill estuary, with one of the key elements being the installation of two 2.5 metre diameter, 16 metre long Archimedes screw pumps. The pump station is part of a comprehensive flood protection scheme that helps to protect Invercargill City and critical infrastructure, including Invercargill Airport, from inundation. The Stead Street carriageway the pump station is located on includes a walking and cycle path and provides an important link between Invercargill and the satellite suburb of Otatara. While much of the city is low-lying, Invercargill Airport is close to sea level. Because of this, the airport is surrounded by a comprehensive drainage network, including stop banks, ring drains and pumps. In 1984, the airport was extensively flooded to depths up to three metres through the terminal buildings. Several of these assets are owned and maintained by Invercargill City Council, while others are managed by Environment Southland to which Fulton Hogan is the main contractor for the pump station project. It aims to protect the area from inundation for the next 50 years and is critical to the 116 properties in the immediate area as well as being a lifeline for the airport, supporting 320,000 passengers plus freight each year. Fulton Hogan project manager Luke Hazlett says the new pump station comprises a main concrete structure, with Colorsteel cladding, a transformer and switchgear platform with a cable basement, a pump house, electrical equipment, outlet pipework, sheet pile wall outlet penetration, plus an inlet structure and wet well. “The [Archimedes] pumps lift water from the inlet structure and discharges it into a wet well where it is gravity-fed through the outlet pipework into the estuary. A viewing platform is connected to the existing three metre side of the shared path on top of the Stead Street stop bank and covers the outlet structure.” Imported from Finland, the Archimedes pumps rotate at 19 revolutions per minute and can move 1.5 cubic metres of water per second. There were some complications during the project which involves undertaking remedial work to lower the height of the pump supports to the required level, resulting in an extended completion date. However, Fulton Hogan has been fully focused on achieving a great outcome for Environment Southland and Invercargill City Council, Luke says. “Our client is always at the forefront of our mind and in turn, that’s the ratepayers as well.” The flood in 1984 was not the only time the airport and the surrounding area has been inundated. In March 2016, a storm surge caused the estuary to overflow onto Stead Street, resulting in road closures and surface flooding of the land surrounding the airport. The need to replace the pump station was also driven by the age of the existing infrastructure which was installed in the early 1960’s. Unlike the original pumps, the new pumps allow for the safe passage of native fish, including large tuna or freshwater eels. The outlet pipes run under the road to the estuary and can be closed during extreme tides or storm events and fish can pass both ways through the pump. “Part of it as well was, when we did the
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