Waikanae Water Treatment Plant

Photograph of the waikanae wastewater treatment plant

Cardno’s specialists have future-proofed the water treatment process for Kapiti Coast District Council and designed and implemented an innovative solution to water supply that addressed community concerns.

Kapiti Coast District Council awarded Cardno the design and construction management contract to upgrade the Waikanae Water Treatment Plant and address water supply issues as part of a $12m project. 

This complex and multidisciplinary project saw Cardno provide project management services along with process, mechanical, electrical, civil, geotechnical, and structural engineering design to the Council across two key components.  

The first component comprised an upgrade to the water treatment plant to future-proof it until 2050 and meet new drinking water standards. Our team coordinated the overhaul of chemical dosing systems and a process of refurbishment of the filter media. 

This increased the capacity of the plant to meet a treated water flow of 25ML/day in a staged approach to align with Council budgets. The operations building interior was also completely upgraded and extended, and the electrical and control systems were renewed across the entire plant. 

The project’s second component required Cardno to design and implement an innovative solution to a water supply issue. While raw water is usually abstracted from the Waikanae River for treatment, our team designed a system to abstract bore water from a nearby aquifer and feed it back into the river to ‘recharge’ the supply during low river flows. This solution maintained the ability to use river water as a drinking water source while alleviating aesthetic and community concerns over using bore water as a source of drinking water.  

The system upgrade included:  

  • environmental studies 
  • three new deep bores 
  • decommissioning of a deep bore 
  • relocation of a surge pressure vessel 
  • construction of 3km of HPPE pipeline 
  • a boresite communications system including radio towers and fibre optic system 
  • a water conditioning swale and flume 
  • a discharge structure into the Waikanae River.