CH2M Beca designed a new membrane filtration plant to increase the supply capacity and water quality supplied to Hawera consumers.
CH2M Beca was commissioned in 2008 as the engineering consultant for the concept, preliminary and detailed design for a new 13 ML/day membrane filtration plant for South Taranaki District Council.
The new facility at Kapuni treats a blend of water abstracted from the Kapuni stream and a deep bore by coagulation, membrane filtration, chlorine disinfection, pH correction and fluoride dosing. The design includes provision for future installation of a wastewater recovery system and makes provision for future 50% expansion of capacity.
A key factor in CH2M Beca’s success in this project was our innovative approach to various process challenges, including:
- solutions which produced a saving in operational costs by an estimated $66,000/annum. These included reduced pumping costs, delivering chemicals in their most economic form, saving energy by using a self adjusting baffle system for flocculation, and using the groundwater supply in a heat pump to reduce heating costs by around 75%.
- application of the S::CAN instrument for feed-forward coagulant dosing control of the highly changeable stream water quality known to occur around Mt Taranaki
- eliminating proposed raw water tanks for stream water by the design of lower cost grit settlement tanks, which also provide a high level of protection to the membranes
- eliminating proposed chlorine contact tanks by optimisation of the design of the treated water tanks, resulting in substantial capital cost reductions.
As part of a separate design-build contract, CH2M Beca also designed two new 4,500m3 treated water reservoirs for the plant, and two further reservoirs for other sites. Rigorous programme management resulted in the commissioning of the plant 12 months ahead of schedule, as well as 20% under the initial cost estimate.