Whangamata Wastewater Pump Station

Due to the expansion of Whangamata and the construction of the new Wastewater Treatment Plant the High Lift Wastewater pump station that discharged the treated effluent required a capacity upgrade. This project consisted of the installation of a new 3m diameter x 7m deep reinforced concrete wetwell directly adjacent to the existing oxidation pond together with a new intake structure, valve chamber and various manhole structures.

New stainless-steel suction pipework was installed in conjunction with the replacement of the two existing 90kW and one 30kW dry pumps. A vacuum priming system designed and installed by the Contractor was also required due to the large suction head required for the new pump arrangement. A new switchboard and PLC Control system was also installed. The mechanical and electrical installation was required to be undertaken in a sequential process to ensure that the pump station remained functional at all times to discharge the incoming treated wastewater.

Upon successful commissioning of the pump station Spartan were awarded a large contract variation to upgrade the existing sludge lagoon so that it could be used as a balance pond for the treated effluent from the new treatment plant. The works involved the desludging of 2500m3 of sludge from the pond, the demolition of the concrete wavebands, and then the installation of subsoil drains and a PE liner together with additional PE pipework, manholes, air vents etc.

The dredging was undertaken using Spartan’s Pit Hog Dredge and dewatered using geobags supplied by Maccaferri. The dewatered sludge was then loaded onto trucks and disposed at a landfill site. Then PE liner was laid over a layer of geotextile and the pond was then filled with treated effluent from the treatment plant to complete the project.