Christchurch Police expect to begin vacating the upper floors of the Central Police Station within the next month.
Police announced in December that they would relocate out of the 13-storey Hereford Street building they have occupied since 1973, because of the risk that continuing aftershocks may degrade internal services in the building.
District Commander Superintendent Gary Knowles told Central staff today that while the staged depopulation of the building would commence soon, it could be several months before all staff were fully relocated to new premises.
"This is not going to be an overnight process," says Superintendent Knowles.
"We need to re-house around 400 staff in a location that will be our base for the next five or more years, until a permanent replacement station is built.
"It is unlikely we will find a suitable existing building, so the most feasible option is to move into a purpose-built temporary construction on a vacant site.
"We are now urgently assessing a number of sites that could accommodate us, both within and close to the Four Avenues.
"The reality is that to design and construct a temporary complex, and get all our people and equipment moved, could take four or five months, possibly more.
"But we will have the process under way as soon as possible, including relocating staff from the upper levels to lower floors and to other stations until such time as the new complex is ready."
Superintendent Knowles says he is reassuring staff and the public that the Hereford Street building remains safe.
"The building itself is structurally sound and we're continuing to work from here in the meantime. Our engineers have reaffirmed that the building's structural integrity is not in question - it won't fail.
"The issue we're facing is that ongoing large aftershocks have the potential to affect the building's internal services - things like doors, plumbing and sewerage, ceiling tiles, electricity supply and the like.
"As a working Police station we need a functional building and we can't take the risk of things failing in the future.
"The experts are telling us there's a high probability that this cycle of large aftershocks will continue, so this is a proactive decision that means we can continue to function effectively and provide a responsive Police service to the city."
Superintendent Knowles says engineers have recommended initially vacating the tower portion of the building, level 5 and above. Staff from these floors would relocate in the short term to lower levels, and to other Police stations around the city.
Once a temporary complex is completed, all remaining floors will be vacated and staff will relocate to the new location. The Southern Communications Centre will also move to the new temporary complex.
Some groups which are currently housed in outbuildings at Hereford Street, such as the dog section, may remain on the site in the medium term.