Erosion control works were carried out at Matapouri Bay in 2007. Photo/Michael Cunningham
Erosion control works were carried out at Matapouri Bay in 2007. Photo/Michael Cunningham
Whangarei
Matapōuri residents will get the chance to have their say about planned sand replenishment works costing an estimated $300,000 at Matapōuri Bay.
A public meeting is planned for tomorrow at the Matapōuri Hall at 3pm.
Whangarei District Council has released proposed plans to move sand that has become trapped in the estuary and put it back on the beach, similar to a controversial project carried out in 2007.
Parks manager Sue Hodge said the council's aim is to take up to 15,000 cubic metres of sand out of several spots in the estuary, transport it to the beach via Matapōuri Rd and Te Wairoa St, place it and re-contour the beach.
"We do not want to impact the ecology of the estuary so we have engaged a highly-experienced ecologist to produce an ecological report. We will not be excavating below the low tide mark, instead taking the sand above that level that has fewer species living in it. Areas with sea/eel grass present will be avoided".
The council plans to take sand from the orange areas and put it in the yellow areas. Photo/Supplied
Hodge said when the roads were built across Te Wairoa and Parangarau Streams, the bridge abutments narrowed the stream channels and confined flood flows, reducing the amount of sand flushed back into the bay and causing more of the beach sand to clog up the estuary.
"At the same time as we add the sand to the beach we would improve pedestrian access and put in lots of dune plants. This would include installing some steps to protect the plantings," Hodge said.
The replenishment project has a life of 15 years, however the council concedes it is not possible to guarantee the longevity of a "soft" engineering solution, as it is largely dependent on the number of significant storm events. The previous project had a life of 10 years, and lasted about nine.
The sand replenishment is estimated to cost $300,000, while planting and new accessways could add another $100,000 but designs have not yet been finalised. Hodge said this year's project incorporates several "lessons learned" from the 2007 project.
Those lessons include replenishing being a cheap and effective way to mimic the natural process, and the ecological impacts of the last project were "absolutely minor and only very short lived".
This time the gradient of the replenishment will be 1:6 as opposed to 1:4 which should improve the life of the design. The council also learnt putting sand on the spit isn't effective and instead needs to focus on the erosion hot spot.
When the work was carried out in 2007, several residents said it was a waste of time. The beach was left littered with poles and fence wire.
Earlier this year, the council admitted "soft" engineering works at nearby Sandy Bay were a failed experiment. It spent $70,000 on that project at the end of last year.
The council said sand management at Matapōuri can't easily be compared to stream erosion management at Sandy Bay as although both are affected by physical changes up stream, each environment has different challenges.
The council plans to lodge a resource consent application and hopes to start the work at Matapōuri Bay in October.
