72 | Short time frame presents challenges The Gibault replacement required precise coordination, involving 20 tradespeople at various stages of the process. New Plymouth District Council: Te Henui Gibault Replacement T T Bernadette Cooney INFRASTRUCTURE Swift collaborative planning and a marathon upgrade meticulously carried out at a coastal pump station in New Plymouth has averted an environmental mess and made future maintenance much easier. The Te Henui wastewater pump station at Autere East End Reserve near the city’s popular East End Beach, developed a leak in a Gibault connection last year. New Plymouth District Council (NPDC) took swift action, initiating a $940,000 emergency repair to prevent the pump station failing further. “The pump station was built in the 1980s, and at the time of construction no provision was made to allow the pump station to be bypassed. It also has no storage capacity, so if you had to shut the pump station down, you only had 45 minutes in the middle of the day before it would overflow into the sea,” says NPDC infrastructure project manager Simon Drake. “During the 1990s, emergency repairs to the rising main were made by discharging wastewater to the environment, but obviously, that’s no longer an acceptable practice.” Simon was responsible for devising a plan to install a bypass pipe around the faulty Gibault and a new spool with connection to the bypass and backflow prevention valve. Timing was everything in this project. The team had to carry out the bypass installation between 1am and 5am, when wastewater flows were at their lowest. By doing so, they were able to extend the available storage time from 45 minutes to four hours, providing enough time to complete the repairs without risking a discharge into the ocean. “We had a four-hour window to cut out a section of the existing rising main and install a four- tonne, prefabricated pipe spool, all in a four-metre-deep trench in the middle of the night,” says Simon. Despite the complexity, the team managed to complete the installation without incident in three hours 40 minutes, finishing 20 minutes ahead of schedule. Once the bypass was installed, the New Plymouth wastewater treatment plant’s maintenance team undertook the repair, which took over two weeks to complete, due to encountering asbestos gaskets. The council had two construction partners on the project, City Care for excavation and site works, and Pace Engineering for metalwork fabrication and installation. Consulting engineers were Worleys NZ for design and construction supervision. The Gibault replacement required precise coordination, involving 20 tradespeople at various stages of the process. “The amount of work we needed to complete in that four-hour timeframe was immense,” says Simon, explaining how the team broke down the tasks into 10-minute intervals to ensure every step was executed flawlessly. Dry runs were also conducted to get the timing perfect. “It’s the project I’m most proud of to date,” says Simon “We found the problem, brainstormed, designed, and constructed the solution all within five months, which is remarkably fast.” As part of its process, NPDC coordinated emergency response plans with the district health board and the local surf club and consulted with local iwi and regional authorities. The project’s success is testament to collaboration and precision that now ensures the safe transportation of wastewater from the city to the New Plymouth wastewater treatment plant, and provides a permanent bypass for use during future maintenance and for the pump station. Proudly supporting New Plymouth District Council Established for almost four decades, Street & Cook Construction have grown to become a dependable and trusted contractor of choice. We are approachable and we will deliver your project with professionalism and integrity in a safe and cost effective manner. 06 751 2299 www.streetandcook.co.nz darrans@streetandcook.co.nz NZ’s leading supplier of: • Flanges • Couplings • Valves • Flange Adapters • Dismantling Joints • Pressed Neck Rings (Collars) sales@nzappletons.co.nz 07 886 4118 www.nzappletons.co.nz Both imported & NZ Stock Safe water for life New Zealand’s largest and most trusted three waters provider. 0508 CITYCARE (248 922) | Fax: 09 966 2714 www.citycarewater.co.nz Proud to support NPDC with 3 waters infrastructure projects
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