Levin Wastewater Treatment Plant Hero

In February 2012, Dr Max Gibbs, a scientist with the National Institute of Water and Atmospheric Research, told Horizons Regional Council's environment committee that the Water in Lake Horowhenua, which adjoins the Levin township and is used extensively by the public, was so toxic that it could potentially kill a small child. This was largely due to the presence of phosphorus, which spurred weed growth in the Lake. The main stormwater drain from Levin township drained directly into the lake and provided 80% of the phosphorus load. Something needed to be done. Horowhenua District Council engaged Hawkins Infrastructure to undertake construction works.

Horowhenua District Council’s aim:

  • To relocate the wastewater treatment plant away from the lake into a man-made storage lake.

What we did:

We were nominated to install a new sewage wastewater rising main, pump station and all associated works on an existing land disposal site (moving what we could from the existing Levin Wastewater Treatment Plant).

The project involved:

  • Installing a new 560ND PE rising main pipeline approximately 7km long, as well as air valves and air valve chambers
  • Constructing the rising main discharge structure, including coffer dam
  • Pressure testing
  • Flushing, cleaning and commissioning the pipeline
  • Constructing a new pump station wet well and inlet structures
  • Supplying and installing four submersible pumps, pipework and valves, flow meters and pig launching ramp pipes and valves and diverting the existing 3150D PE pipe
  • Constructing a new motor control centre building, including installing all electrical, lighting and controls to it and to the new pump station
  • Commissioning the constructed and installed system.

Unique challenges:

  • Installing pipes through a challenging stream crossing. 
  • In order to install all mechanical pipework and make connections with the existing effluent pond, the pond needed to be drained and temporary measures put in place to keep the current pump station going. We implemented a system called “Aquadam”, a water-filled barrier that can be used as a dam or cofferdam for stream diversions, dewatering boat docks or pond liners for repair. This enables Hawkins to dewater a small area of the existing pond while the pond remains fully operational.

The outcome:

The project successfully completed its commissioning phase and the system was fully operational by 2013. As a result of the wastewater treatment plant’s relocation, the process to improve Lake Horowhenua’s water quality can begin.