Project Overview
Location
Whau Valley, Whangārei
Date Completed
2021
Services
Cut. Form. Build.
Installation
Engineering Support
Longveld partnered with Ventia on the Whau Valley Water Treatment Plant for Whangārei District Council. Our job was to mechanically design and fabricate large-scale stainless steel filter vessels for critical water infrastructure. The project expanded our fabrication capability, sharpened our engineering processes, and delivered complex pressure equipment built for long-term performance.
Large-Scale Filter Vessels for Water Treatment
For Whau Valley, Longveld was engaged to manufacture a series of pressure filter vessels central to the water treatment process. The scope was significant, both in size and technical demand.
Our team delivered:
- Four horizontal pressure filter vessels, each 3 metres in diameter and 10 metres long, fabricated and delivered in two stages. The vessels include integrated access platforms and required tailored mechanical design and fabrication due to their departure from standard vertical filter configurations.
- Batch tanks and flocculation tanks supporting the full water treatment system
The outcome reflects careful planning, disciplined execution, and a focus on build quality at every stage.
Water Infrastructure Design, Delivered In-House
Longveld completed the mechanical design and fabrication of the vessels in-house, working directly to client specifications and relevant standards. The design was developed to meet operational requirements while complying with AS 1210 pressure equipment standards.
Internal technical reviews confirmed alignment with design, operating, and inspection criteria, providing a robust engineering foundation for fabrication and long-term service.
Quality Assurance for Critical Water Infrastructure
Given the role of the vessels within essential water infrastructure, quality assurance was comprehensive and tightly controlled throughout the project.
Across fabrication and assembly, Longveld implemented rigorous inspection and verification processes, including non‑destructive testing (NDT) such as visual and penetrant inspections at multiple stages, all completed in accordance with specified acceptance criteria.
Complete QA documentation, including weld mapping and inspection records, was maintained to ensure full traceability and provide confidence to all project stakeholders. This disciplined approach supports reliable performance and long‑term service in infrastructure designed to operate for decades.
Precision Stainless Steel Fabrication
The vessels and platforms were fabricated from 316L stainless steel, requiring controlled forming, welding, and inspection processes. Welding procedures, NDT records, and quality reports supported every stage of the build.
All equipment was delivered to site on schedule, supported by clear documentation and engineering sign-off.
A Milestone in Water Infrastructure Fabrication
The Whau Valley project marked an important step in Longveld’s capability to deliver large-scale water infrastructure mechanical design and fabrication.
We contributed to infrastructure the region depends on every day — applying careful engineering, disciplined fabrication, and a collaborative approach from design through delivery.
