Mangakino Wastewater Treatment Plant Upgrade

Works consisted of the construction of a new proprietary building housing two blowers and a control room, two new concrete SAF tanks, two new concrete Humus tanks, a new pump station, valve chamber, flow meter and splitter box, conversion of an Imhoff tank to a septic tank, a new 30,000L storage chamber, modifications to a variety of manholes and diversions to the new system. The existing plant consisted of a sand filter, septic tanks and an Imhoff tank. The existing plant was to remain operational throughout the upgrade.

The concrete Humus and SAF tanks were a design build component of the contract and were constructed with precast wall panels fabricated on site. The SAF tanks were square tank with insitu floor with a Xypex waterproofing additive in the concrete. The Hummus tanks are curved wall panels and a domed insitu concrete floor to collect sludge and clarified effluent drained off. A steel curved panel mould was made for the wall panels and the domed floor was formed by sprayed concrete. A polyurea coating was then sprayed to the surface for chemical resistance. These tanks were built on piled foundations.

Structural steel walkways between the tanks provided access for operation and maintenance. The new pump station consisted of 2050 manhole risers 4m deep was located within a park reserve

outside the treatment plant compound. The 30m2 storage tank is constructed of 2100mm diameter concrete pipe sections laid horizontally is situated along side the pump chamber.

Innovation:

The conforming design for the SBR tanks were circular however we adopted an alternative square design and precast the panels on site resulting in cost savings to the client.