Upgrade of Electrical Systems at Christchurch's Largest Wastewater Pump Station

The Contract Works can generally be summarised as the following: Pump Station 11 is a critical part of the Christchurch wastewater network. It is a Terminal Station, meaning that it is the last link between multiple upstream pump stations, large catchment areas, and the Treatment Plant. The pump station receives large flows from the city's southwest, central, and western parts.

The station is equipped with 4 x 320kw submersible pumps and is Christchurch's largest wastewater pump station by volume. Wastewater flows into the station and is divided into two wet wells, which electrically operated penstocks can isolate. The two wet wells are equipped with two pumps in each wet well. Each set of two pumps sends the wastewater into two rising mains, which terminate at the CWTP.

The rising mains also have electrically actuated valves to isolate or cross-connect the pipes. Backup Generators supplement the two Main Switchboards, each providing a good level of redundancy and allowing for Load shedding during an Orion Control Demand Period. Two PLCs operate the station, providing redundancy on a duty/standby basis. A third PLC is used for data transfer between the station and Network control.

The pump station was constructed in 2004 and has not had any upgrades to the electrical equipment other than occasional repairs and plant additions to enable better site visibility from Network Operations.