CH2M Beca assisted the local authority to upgrade their water treatment plant to accommodate stretched demand.
With population growing and existing facilities stretched to the limit, New Plymouth District Council (NPDC) needed to upgrade their water treatment plant to cope with additional demand.
This Design Build water treatment plant upgrade expanded the existing plant capacity from 45,000 m³/d to 70,000 m³/d and upgraded its performance to meet the requirements of Drinking Water Standards New Zealand ( 2005). CH2M Beca was the principal designer for the Design Build contractor, Fulton Hogan. Our scope included tender design, detailed design, construction support and commissioning.
CH2M Beca and Fulton Hogan focused on aiming to maximise the value that could be extracted from the existing infrastructure with some innovative adaptation of the existing plant. This approach identified a clear winner in terms of cost and performance outcomes. The upgraded process includes:
- powdered activated carbon dosing prior to the plant for taste and odour removal
- pre lime and CO2 prior to coagulation for improved coagulation control and reduced water corrosivity, which are important for waters in the Taranaki region
- new inlet works constructed including an innovative hydraulic flocculation system that self adjusts with varying flow to provide uniform mixing energy
- tube settlers installed in the existing clarifiers to enable a 50% increase in capacity
- existing filters fully refurbished, including new floors suitable for a simultaneous air water scour system that provides substantially improved filter washing and a filter to waste system
- new chemical dosing systems and control system.
NPDC required that the treatment plant continue to be fully operational while the upgrades took place. CH2M Beca specifically designed the upgrades and worked with the contractor and NPDC’s operations team to ensure these needs were addressed.
The plant was completed on time, to the required quality standards and within budget.