Friday, 5 July 2013

Hobart's Water Supply

When Lieutenant Collins founded the settlement of Hobart Town in 1804, one of the major considerations was the fresh and adequate supply of water, because Tasmania's original settlement at Risdon Cove had failed for just this reason.
The Hobart Town Creek, later to be known as the Hobart Rivulet, appeared to satisfy this essential need, but by 1828 the government officially recognized that wastes from a variety of industrial, agricultural and human sources were polluting the water, and that during the late summer months the flow of the rivulet was sometimes reduced to a trickle.

Accordingly a brick conduit, called the town tunnel, was built from the Cascades (around four kilometres upstream from Sullivan's Cove) to a large reservoir at the Barracks. Completed by 1831 it actually had the effect of increasing water consumption, as piping from the Barracks soon networked throughout the township. Extra water was drawn from the upper catchments of Browns River and Fork Creek and fed into the Hobart Rivulet via interception pits and a deviation channel along the south-eastern face of Mount Wellington. Today part of the channeling is still visible and follows the course of Mills Track above The Springs on the road to the Pinnacle.

But demand for water continued to increase. In 1858 it was recommended that a large reservoir or series of reservoirs be constructed on the Sandy Bay Rivulet, capable of holding four months' supply, without any inflow, for 30,000 inhabitants. Because of slippage and seepage problems the task took from 1861 to 1895, but in that latter year two reservoirs with a capacity of 500 million litres were completed.
Today, these reservoirs form part of what is known as Waterworks Reserve, a popular picnic and barbecue area. The original supply of water to the Waterworks reservoirs was from Fork Creek, captured by a circular masonry intake known as the Wishing Well.

In 1862 John Gillon (who also built sluice houses at Browns River and Halls Saddle), supervised construction of a stone dam across Fork Creek, from which water was carried by wooden troughing to another dam at Browns River (the Bower). The troughing was replaced by pipes in 1868, when the water supply scheme was extended to Long Creek, a few kilometres to the south.

In 1881 there was a major addition to the Hobart water supply with the construction of a line from St Crispins Well to the south, and this called for construction of the "Wishing Well", in which water from Fork Creek joined the bigger flow from Plains Rivulet. The 1868 pipes to the Bower were then replaced by a 16 inch (40 cm) main. The well was fitted with a "bell-mouthed pipe, wire gauze screen, shut-off sluice and scour", according to a newspaper report of the works.

The original well had no safety precautions, although no human casualties are recorded. Before intake screens were installed, platypus, which occur in Mt Wellington streams, were known to drown in the well. The eminently practical reasons for building this structure did not stop people from ascribing to it the power to make wishes come true. For this to happen, according to local folklore, you must walk around the well three times after making your wish.

Wooden troughs transferred this water to a second intake at Browns River called the Ferntree Bower. When this part of Browns River became known as the Bower (later Fern Tree Bower) in the 1860s, the scene was very different from what it is today. A dam built across the river in 1862 made a pond, around which grew overhanging tree ferns. It became the mountain's most famous beauty spot. People walked (or promenaded) along the track following the water line from the saddle at Fern Tree Inn to the Bower, where they could enjoy a leisurely picnic or a walk upstream to Silver Falls before heading home.

Over time, rustic benches, tables and shelters were installed. In 1880 the Bower was the subject of controversy when the Hobart City Council removed trees to allow work to be done on new masonry troughing. The Council pointed out that the Bower was first and foremost a water collection point, but did take steps to lessen the visual impact of the tree removal.
A major problem confronting the designers of Hobart's original water supply around 1860 was how to get the water from the Mountain's southern slopes across Halls Saddle to the city outskirts. The solution was unusual in its extensive use of wooden and masonry troughing and associated sandstone features.

From dams across Fork Creek and Browns River, the water had to be conveyed across Longhill Creek, (now known as Dunns Creek) to the Saddle. A wooden bridge carrying troughs across the creek, built in 1862, was in serious disrepair by 1880 when a contract was given to stonemason Joseph Hawkes to build two sandstone aquaducts designed by the Director of Waterworks, C.W.S James.

Sandstone for the aquaducts appears to have been quarried at Gentle Annie Falls and transported up the Pipeline Track. The work was completed by late 1881. Much of the masonry troughing on the track has now been concealed underfoot. The cast iron pipes on the aqueducts are a later addition.

As the pipeline progressed, the working conditions in which it was excavated and constructed became colder and wetter with only several months of good weather in a year. Debates and delays in Council over construction and funding meant this good weather was lost for the contractors and workers. The Council took some time to agree on stone bridges as opposed to an iron siphon, and it later was in dispute with the contractor over claimed additional expenses.  From here, the water flow continued towards the reservoirs, flowing through what is known as the “Sluice House:

This little building, known also as the "Valve House", was built in 1862 by mason John Gillon, who also built the receiving house and valve tower at the lower reservoir and dams at Browns River and Fork Creek. The cost of the whole construction was £63/7/- ($126.70 in modern currency). The hammer-dressed sandstone probably came from the outcrops at Gentle Annie Falls. The building contained a sluice gate made by the City Corporation, located directly above the original pipeline. The sluice could be raised or lowered to control flow through the pipe, allowing water to be diverted down the hillside to Sandy Bay Rivulet when work was required on the water line below this level.

From here, water moved along masonry and timber ducts to the receiving house that stands to this day and is still in use as a shelter and interpretive centre at the Waterworks Reserve. The walk along the Pipeline track is one of the most popular in Hobart and the interpretative signs along the way and the historical pieces of the original infrastructure make for a fascinating view into the development of the water supply for Hobart Town!

Much of the information is taken from the from Hobart City Council signs found along the Pipeline track
The Pipeline Interpretation Project. An initiative of the Fern Tree Community Association, supported by the Hobart City Council. Original research by Lindy Scripps.