Waitoa Industrial Estate Limited Wastewater Treatment Plant Upgrade

The upgrade improved the primary treatment system for the tannery which included additional sulphide waste stream oxidation capacity and a new dissolved air flotation plant.

Works also included the construction of HDPE lined aerated lagoons, a SBR for treatment of non-tannery wastewater and a buffer lagoon for treated wastewater.

Besides the numerous pump stations, pipelines and valves, we also installed and commissioned a tertiary filtration, UV disinfection system, solids dewatering facility and a chemical dosing system.

Major works included:

• In excess of 40,000m3 of brown rock imported and placed to form the lagoons

• 13,200m2 of HDPE lining and geofabric installed

• 6km of pe pipe installed through a live factory site

• Installation of Four glass fused storage tanks.

• Large mechanical pipework installation for all the pumps and associate equipment

• Installation of a DAF unit, Wedeco UV units and disk filter

• Installation and commissioning of two polymer dosing systems

• Installation and commissioning of two chemical dosing systems

• Construction of two concrete block MCC buildings

Innovation:

Given the earthworks had to progress during the winter season, it was identified during the tender phase that using the natural clay-based material to construct the pond out of, was a risk to the programme. Our local knowledge allowed us to identify a source of locally quarried by-product material which was accepted as a viable alternative to construct the embankment out of. Importing the material ultimately saved months of wet weather delays on the programme.