Britomart
Meeting the challenge
Inside the CPO (click to enlarge)
Station construction (click to enlarge)
Made from 2,500 square metres of glass on a steel frame, the Glass House serves as an entry point to the station platforms, a giant light source for the station platforms, and a natural ventilation system (click to enlarge).
"Volcanic" cones that provide natural light the length of the station (click to enlarge).
Britomart was a large and complex project, so it should come as no surprise that there were engineering challenges aplenty. Take the utility lines, including a power line and the Quay Street stormwater culvert, which had to be protected and suspended beneath a temporary bridge (using crane sections) while work went on around it. And the "extra strong" 1912 CPO building, whose reinforced walls proved remarkably tough to cut through.
Its floor had to be lowered by 1.5 metres to allow ground-level access. And then the CPO was riddled with asbestos. "It had been used in the plaster and the concrete fill between the timber joists," says Mr Hennephof, "We had to encapsulate the whole building and remove the material. The joists were stripped and sprayed with epoxy. Everything we removed was bagged and taken to a special tip."
Several design elements were new for New Zealand, including the stainless steel mesh in the station's ceiling and the 11 eye-catching "volcanic" cones that provide natural light the length of the station. The 34-tonne cones were constructed from shotcrete and reinforcing steel on the station floor, then jacked up for bolting into the ceiling. There was even a question mark hanging over whether bolts would hold their weight (they did!).
Buried history
The area also has historical significance, and archaeological experts were always on hand. During the work, part of a 138-year-old structure was unearthed, complete with "interesting" artefacts, including bottles and cups of the period. "It took a couple of digs before they realised what was under there," says Dale Burtenshaw, Downer Engineering's senior project manager, "but it soon became quite obvious it was a wharf or jetty." It turned out to be Gore Street Jetty – whose construction was commissioned in January 1865 for the princely sum of £3,318 19s lid.
Made from an unidentifiable Australian hardwood, the wharf had been demolished when the site was reclaimed in the late 1800s. Its remains were removed by simply cutting off the superstructure at low tide. The remaining piles were easily cut through during further excavation. A second wharf was found at the end of Customs Street, as well as the pile foundations of tracks from the original railway station.
