The anatomy of a city

Dunedin Drainage Board workers lay the intercepting sewer along Cumberland St near what is now Queens Gardens on March 28, 1906. Photo from Otago Witness

We might admire cities we live in or visit for their architecture or landscape, but few of us give any thought to the infrastructure that supports a city and makes living in it possible.

Much of it is invisible, such as pipes bringing clean water and sewers removing waste, but essential to public health.

Underground electricity, phone and broadband cables are likely to go unremarked, or be taken for granted.

Such things are brought to light in two new brochures describing engineering heritage trails in the centre of Dunedin.

Both one and a half hour selfguided walks start at the Otago Settlers Museum and take people around the railway station, Octagon, Moray Pl and Tennyson St area, and around Queens Gardens and the Exchange, revealing fascinating snippets of information about sewers, structures, machinery and large earthworks, such as the demolishing of Bell Hill and the reclamation of the harbour mudflats.

The brochures, to be launched this month, are produced by the Otago Chapter of the Engineering Heritage group of the Institution of Professional Engineers (IPENZ), and aim to recognise the vision, skills and tenacity of early engineers who were pivotal in the city's development and early prosperity.

Among the fascinating stories told in them are those of the lowering of Bell Hill, and the city's sewers.

• Bell Hill
Dunedin's landscape 160 years ago had a very different profile.

The shoreline was close to Princes St, and the tides washed across mudflats that are now Queens Gardens, and around the foot of Bell Hill near where Dunbar St is now.

This prominent landmark had been reserved by the founding fathers for building a church, and for a while housed a bell, a gift from Scotland to First Church, that was rung to mark working hours or raise an alarm.

It still stands outside First Church. Bell Hill separated the Octagon and the swampy northern end of town from the southern end and the main jetty at Jetty St, near what are now Bond and Crawford streets.

With its summit between Dowling St and Moray Pl, it was too steep for wheeled vehicles to cross and sloped too sharply into the harbour for a road to pass around it.

In 1858 a six metre wide cutting was blasted through the rock to extend Princes St and link it to the Octagon and the northern part of the town.

However, with the influx of ships and people during the gold rushes of the 1860s and the need for more flat land around the harbour for commercial expansion, the Provincial Government decided Bell Hill, which was still a major barrier, should be demolished and used to reclaim the mudflats, starting with the area that is now Queens Gardens.

The owners of 33 houses, nine shops, eight stores or workshops, a church and a hotel had to be compensated and work started in 1862.

The earthworks, which took more than a decade, used both private contractors and prison labour.

Rock was blasted and shovelled into horsedrawn trucks which ran on rails and emptied on the tidal flats.

As with most big projects, there was controversy and even some scares, as when in December 1864 a blasting charge miscalculation meant pieces of rock rained down in Princes St, according to the Otago Witness.

By 1874, the waterfront was a straight line along the eastern side of Crawford St, and First Church had been built on the truncated stump of Bell Hill.