28 June 2019
Desilting NPDC’s Pukekura Park lakes will be the first step in creating a rare inner city haven for some of our native wildlife.
Often called the jewel in New Plymouth’s crown, the park is also home for kākahi (freshwater mussels) and banded kokopu.
But silt has been building up in the park’s waterways in recent years, and contractors will start trial work to clear them next month.
The trial, phase 1 of a multi-million-dollar project, will use a one-person Truxor amphibious dredge. Made in Sweden, the Truxor runs on rubber caterpillar tracks to avoid damaging the paths and it can carry a range of tools for removing silt and debris.
The Truxor has already been used successfully on projects for Auckland Council and in other parts of the country.
“NPDC’s Pukekura Park is a Garden of National Significance and holds the Green Flag of a world-class park. It’s the green heart of New Plymouth – we have to keep it pumping so locals and visitors continue to enjoy it,” said NPDC Infrastructure Manager David Langford.
“It’s also a rare urban habitat for some of our native species and we need to give them an environment where they can flourish,” said Mr Langford.
“The last attempt to desilt the lakes hit technical problems, and we don’t want to repeat the mistakes of the past which is why we’re doing extensive trials. It’s a major project and we want to ensure ratepayers’ money is being spent wisely so these trials will tell us if it works as a large scale project.”
As well as the plant-life on the banks, the lakes are also home to eels (tuna), kōura (crayfish) and other water life.
Desilting the lakes would also make a better home for native birds such as the kawau paka (little shag), which can be seen in the trees on the banks, and pūtangitangi (paradise shelduck), an unusual duck because the female has a pure white head making it more eye-catching than the male.
If the trial is successful, visitors should see clearer water and fewer weeds in the lakes, and it should put an end to the distinctive smell that can come with low water levels.
The trial will take place in the Main Lake and the tributary waterway in the Truby King Dell which runs between Brooklands Road and Vogeltown Park.
“We’re asking our community to bear with us as NPDC carries out this essential work to care for our environment and maintain one of our district’s star attractions,” said Mr Langford.
It’s been more than 20 years since the lakes were last fully desilted, and this is a multi-million project which will be done in phases.
How the desilting trial will work:
- The Truxor uses a range of tools for collecting and chopping up silt and debris from the lake floor.
- This is sucked up through a hose and pumped to a Geotube bag, which looks like a large tube.
- The Geotube keeps in the silt and allows the water to drain back into the lakes.
When the water has drained, the Geotube with its sludge is trucked away to be disposed of in an environmentally-friendly way.