A decision is yet to be made on the plans and a resource consent application is currently before the council.
A soil expert says cyclone-related silt poses a health risk if it becomes airborne and is inhaled, but those risks can be mitigated by keeping silt wet or covered.
If the plans are approved, 350,000cu m of silt (roughly 50,000 truckloads) will be trucked, mainly from Esk Valley, to the council-owned development site at 250 Westminster Ave in Poraiti, behind the Hawke’s Bay Rugby Union headquarters.
The silt will be sorted and spread out to create “an optimum ground level” for about 200 residential sections as part of the final stage of the council’s Parklands Residential Development - a subdivision which has been rolled out in stages since 2005.
Those sections will then be sold off for people to build homes on in the future.
The silt will also be used to create new rugby fields for Pirates Rugby Club near the current rugby union headquarters.
“The proposal presents a win-win opportunity for the efficient removal of silt from flood-affected properties while providing fill material necessary for enabling future residential development at Parklands,” the proposal read.
“The proposal provides significant economic benefits through savings for Napier ratepayers by utilising a conveniently located, suitable source of fill.”
The development site in Poraiti, Napier. Pictured is soil being stockpiled for another project with Pirates Rugby Club. Photo / Warren Buckland
Prior to the cyclone hitting, fill material was initially going to come from a commercial provider for the housing project at a cost to the council.
The 37ha development site at 250 Westminster Ave is located close to hundreds of existing homes.
“Dust will be managed through the use of water carts or irrigation,” the proposal read.
“In windy conditions, incoming loads shall be covered prior to their delivery to site.
“The applicant will adopt best-practice procedures such as ... watering the site to minimise and avoid the discharge of sediment and dust beyond the boundary.”
The proposal which includes using cyclone silt for the last stage (Area 4) of the Parklands Residential Development. Photo / Napier City Council
The proposal includes plans to have all the silt grassed over within 18 months of earthworks finishing.
Lincoln University associate professor Peter Almond, from the soil and physical sciences department, said cyclone-related silt can pose a health risk when airborne.
“It’s silica-dominated and it can produce silicosis,” he said of silt dust.
“If people breathe it into their lungs, it gets lodged there and causes irritation and ... can cause lung problems and breathing problems.
“It’s not benign stuff. When it gets in the air and people breathe it in and it is of that silt size, it is dangerous.”
The project site (circled). Photo / Napier City Council
However, he said there were ways to stop it from becoming airborne and mitigate the risk, including “by keeping the material moist”.
“If it is moist, you get water films around it and all these grains stick together.
“The other obvious thing is to vegetate it or cover it so that it can’t get blown up by the wind.”
Up to 120 trucks will come and go from the site each day, delivering the silt, and truck movements will be restricted to between 7.30am and 5.30pm, Monday to Friday.
Truck access to the site will be from the roundabout on Orotu Drive, opposite Pacific Avenue.
Gary Hamilton-Irvine is a Hawke’s Bay-based reporter who covers a range of news topics including business, councils, breaking news and cyclone recovery. He formerly worked at News Corp Australia.
