Recognised as a structure of national historic importance the Coppermine Engine House was built in 1854 to pump water from what is believed to be the first underground mining operation in New Zealand. It sits at the high tide mark on Kawau Island’s south western coast and is suffering major erosion from wave action and salt laden rain and winds.
157-year-old Coppermine Engine House on Kawau Island
“This work is being done because the Coppermine Engine House was not built to withstand being blasted by wind, rain and waves for more than 150 years,” says the Department of Conservation’s Warkworth/Great Barrier Area manager Tim Brandenburg.
“It was built from soft sandstone that makes it highly susceptible to erosion and the sea, wind and rain have taken their toll over the years. We’ve begun work to protect this nationally significant historic structure from the waves that have eroded the sandstone particularly at the base of the west wall.”
“Around 50,000 people visit Kawau Island every year and many walk the tracks that lead to the engine house. The chimney is also an iconic image for people boating in the Hauraki Gulf Marine Park.”
The project has posed some major challenges and we’re delighted it’s now underway,” says Tim Brandenburg.
DOC has worked closely with Salmond Reed Architects on the project, a company that has been involved in the restoration of some of New Zealand’s most historic buildings.
Salmond Reed Architects spokesperson, Tracey Hartley, says the work will reinstate the structural integrity of the Coppermine Engine House. “The main challenges we’ve faced have been sourcing and transporting the sandstone to the island. We’re also using traditional hydraulic lime for the repair work as it’s more compatible with the sandstone.”
Sandstone boulders from Matakana quarry
The work to protect, repair and restore the Coppermine Engine House set on Kawau Island will cost $229,000 and involves:
- Building a barrier wall in front of the engine house’s west wall to protect the base of the structure from destructive wave actions.
- Repairing and restoring the eroded base of the engine house’s west wall. This involves removing masonry blocks and cement based mortar used for repair work in the early 1980s before DOC was established in 1987. This has actually accelerated the erosion problem. The masonry blocks will be replaced with large sandstone blocks which are the same as the original blocks used to build the engine house.
- Replace eroded masonry blocks used for repairs to the chimney entry opening in the 1980s with new sandstone blocks.
Sandstone blocks cut from boulders to restore the engine house
Copper mining on Kawau Island
Copper was discovered on Kawau Island in 1842 and mining began two years later. The copper mine on Kawau is believed to be the first underground mining operation in New Zealand. Extracting the copper ore became difficult because most of the mine workings were below sea level and had to be constantly pumped free of water.
Mining was halted in 1852 and resumed in 1854 when the Coppermine Engine House was built to address the flooding. It housed a 50 horsepower steam engine driving a Cornish mine pump. It was modelled on mining pump houses in Cornwall where many of the Kawau miners came from. The engine house pump enabled further mining but not for long as it appears to have halted for good in 1855.