Case Study

Project Name

Domain Rd, Lake Hawea - Pump Station and Emergency Storage

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Client and Location

Fulton Hogan (working for Queenstown Lakes District Council), Lake Hawea

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Project Duration

November 2025 – April 2026

 

Project Description

The wastewater management system in place around Wanaka and Lake Hawea was described as “not viable” by the Wānaka-Upper Clutha Community Board. The need for a new Pump station and wastewater storage facility in Lake Hawea was recognised and the project was awarded to Fulton Hogan. Alpine Civil was contracted to deliver the installation of all underground services associated with the new pump station and pump station building at Domain Rd, Lake Hawea.

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Alpine Civil's works

The project began with the stripping of topsoil and then the complete excavation works for all underground services. Excavation works were extensive and a 30tn GPS enabled excavator was utilised to provide efficiencies of scale. The zone extended to an area of approximately 35m x 40m and to a depth of 4m. This area was designed to house 7, 3m diameter x 15m long fibreglass reinforced (FRP) emergency storage tanks. Each tank required securing to ground and   required its own 1050mm x 4,000mm manhole and associated connecting 300mm diameter pipework. The entire area required backfilling with graded material to industry standard.

 

A 1,500mm diameter x 5,000mm deep manhole was installed on an existing live sewer line which services all wastewater flows from the Lake Hawea township.

 

A 6,000mm deep excavation was required to house a 3,000mm diameter wet well pump station. Additionally, installation of odour ducting and biofilter was required with associated water services and electrical and communications ducting.   

 

Project Challenges

The size and depths of the excavation created challenges with both access and the correct backfilling. This challenge was tackled with a stage approach to the excavation and creating access for the 30tn articulated dump truck (ADT) to access the bottom of the excavation to create efficiencies in loading and cartage to stockpile.

 

The new 1,500mm diameter manhole (5,000mm deep) was constructed over the existing sewer pipeline that carries all flows from the Lake Hawea township. The cutover from the old connection to the new manhole was completed by blocking the upstream pipe and utilising two 10,000 litre sucker trucks to suck out the manhole and then pump this into the existing pump station manhole which was approaching 100m from site.

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The entire storage tank area required backfilling with “peas” small, smooth, and rounded stones. Limited access and the scale of the site required the use of a 20tn long reach excavator and 1 x 30tn excavator fitted with a dipper arm extension to reach the middle of the backfill area.

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Outcome

Fulton Hogan provided positive feedback on the project highlighting the quality of work and the approach to safety on a challenging site. No incidents were reported and the project was completed on time, to specification and on budget.