An earthquake damaged lighthouse which teetered on the edge of a cliff at Godley Head near Christchurch in New Zealand has been rescued in what has been one of the more interesting construction related challenges thus far in the Christchurch rebuild.
Following an earlier unsuccessful attempt on July 5, the Department of Conservation used professional abseilers and a helicopter last week to lift the structure off the cliff in an operation that took around two hours.
The lighthouse's copper dome, which weighs about a tonne, was lifted off first along with the outer glass housing, leaving the 900-kilogram metal house to be removed separately by helicopter.
The lenses were then boxed up before they too, were transported off the cliff by helicopter.
Project manager Grant Campbell says the operation required creative thinking.
"This beautiful old structure had an extremely lucky escape and was left clinging to the cliff by its toenails after the February and June earthquakes in 2011,” he says.
Built from locally quarried stone, the original Godley Head lighthouse was first lit in 1865 and was fully automated in 1976.
During the Second World War, fortifications were built about the lighthouse and a battery of six-inch guns was installed. Due to its strategic vantage point, Godley Head was taken over in 1851 as a Defence Reserve for military purposes.
As the lighthouse was in the direct line of fire of the guns, the old tower and lighthouse keepers’ cottage were demolished and the lighthouse moved further down the cliff face.
After being damaged in the Christchurch earthquakes, the buildings and tower were gifted to DOC for possible removal.
Grant says the structure and operating mechanisms of the lighthouse are of significant historic importance, as the eventual aim is to restore the house on a new concrete base.
In the meantime, the unit, along with the prism glass, prism housing and light mechanism, will be stored in a nearby DOC compound.