lower prospect canal reserve

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the canal reserve story

The Lower Prospect Canal Reserve is a unique parcel of bushland that snakes through a densely populated area of Western Sydney. The corridor stretches for approximately 7.7 kilometres from Prospect Reservoir to Sydney Water Pipehead at Albert Street, Guildford (see map) and varies in width from 40 metres to 100 metres covering an area of approximately 54.6 hectares.

The Canal Reserve is one of the last remaining remnants of natural Cumberland Plain woodland in the Sydney basin and contains a number of rare and endangered plant specimens.

The reserve has survived the intense urban development that surrounds it, due to its use, for over a 100 years, as part of the water supply system for Sydney. That use came to an end in May 1995 leaving the community with the chance to gain a spectacular parcel of land for recreational purposes. August 2003 saw the reserve opened to the community with a cycleway/walkway running it's full length and connecting with other cycleways that extend across a great part of the Sydney metropolitan area.

how did the canal reserve happen

In the 1860s following droughts and population expansion, the need for a larger and more reliable water source was required for Sydney. A Special Commission, in 1869, recommended construction of the Upper Nepean Scheme. The proposal was approved in 1877 and work commenced in 1880.

The Upper Nepean Scheme saw water from the Upper Nepean, Avon, Cordeaux and Cataract Rivers channelled via tunnel, pipes and open canal to Prospect Reservoir. From Prospect Reservoir the water supply moved through an open canal known as the Lower Prospect Canal along the corridor now known as the Lower Prospect Canal Reserve.

The Upper Nepean Scheme is truly a remarkable, even heroic, feat of precision engineering when it is realised that it was constructed without the array of construction equipment and technology that is available today. It was built by hand with the aid of horsepower (real horsepower) and that's it.

The whole scheme relied on gravity and therefore demanded unerring accuracy during construction. The Lower Prospect Canal falls approximately 2 degrees over its 7.7 kilometre length. The scheme, including the Lower Prospect Canal, was completed by 1888.

tell me about the lower prospect canal

Originally the Lower Prospect Canal was constructed of masonry, but between 1907 and 1912 it was relined with pre-cast Monier plates and concrete. The relining raised the height of the canal walls and thus increased the capacity which was needed to service the growing water requirements of Sydney.

A portion of the canal known as the Covered Way, located at the base of Prospect Hill near Hyland Road Greystanes, collapsed in 1904 and was rebuilt in 1905. The Covered Way is essentially an enclosed portion of the canal that protected the water supply from contamination that may have entered the canal due to the steepness and proximity of Prospect Hill.

Besides the Covered Way there are a number of other significant structures that formed part of the Lower Prospect Canal. The most notable being the Boothtown Aqueduct (now the Greystanes Aqueduct) which was built to bring the water flow across a valley while keeping the canal level. The aqueduct has been added to the register of the national estate and has a heritage protection order upon it.

The brick aqueduct has 22 arches each with a span of 9.1 metres and is 225 metres in length overall. In 1892 the parapet walls of the aqueduct failed, falling into the creek below. The walls were rebuilt and strengthened with a concrete lining and tie rods. Due to its failings and inability to have its capacity increased the aqueduct was by-passed in 1907 with the construction of the inverted syphon.

Greystanes (formerly Boothtown) Aqueduct

photo courtesy of Environmental Partnership
The Boothtown Syphon (now the Greystanes Syphon) is a 3.15 metre reinforced concrete pipe built on the southern side of the aqueduct that allowed the water supply to traverse the valley using gravity to push the water back up into the canal on the other side.

The aqueduct was blocked with concrete plugs to allow diversion of the water flow into the syphon. The syphon inlets were built as ornate castellated concrete towers with steel trash racks and sluice gates to control the flow. At the time of construction it was the longest continuous concrete work of its kind in Australia.

Another structure that is heritage listed is the valve house and horseshoe (so called due to its shape) receiving basin at the head of the canal at Prospect Reservoir. Inlet pipes in the base of the receiving basin allowed water to pass from the reservoir into the canal to start its journey to Pipehead. The inlet pipe flow was controlled by a set of valves housed within the valve house adjacent to the receiving basin.

Lower Prospect Canal valve house and horseshoe receiving basin
at Prospect Reservoir
At the far end of the canal prior to it entering Pipehead there are two sedimentation chambers and a central bypass which were used to trap sediment from the water before it entered the Pipehead pumphouse and then the pipes that deliver it to the rest of Sydney.

On the southern side of the canal, near Percival Road, there are two inground tanks, the first built in 1895, that were used to supply Smithfield with water. Over the years these tanks have been neglected and were difficult to locate due to overgrowth.

what happened next

The Lower Prospect Canal was made redundant in May 1995 when Sydney Water commissioned an underground pipeline at a cost of $54m.

Prior to the pipeline becoming operational the State government of the day was seriously considering selling a major part of the Canal Reserve for medium density housing. Not only would this have been a disaster for the environment, it would have severely strained the infrastructure and amenity of the surrounding suburbs.

The local community rallied against this proposal, quickly recognising the intrinsic value of the reserve. This saw the formation of the Canal Reserve Action Group (CRAG). The full story of CRAG can be viewed by clicking here.

CRAG put forward the communities wishes for the reserve and after lobbying the NSW State Government from 1994 to 1997 government funding of $100,000 saw a steering committee formed to oversee the production of a Plan of Management - the first step in having the land turned into a reserve for public use.

The Plan of Management was released in December 1998 and May 2000 saw the first allocation of funds to allow work to commence on the reserve. Work commenced on 17 April 2001 and the reserve was progressively opened at the completion of each stage of the cycleway. The final stage was completely opened on 28 August 2003 when the gate to Prospect Reservoir was unlocked.

The work to remove the canal as a falling hazard and turn it into a cycleway resulted in approximately 150,000 cubic metres of fill being placed in the canal. This fill was only placed after a rubble drain was constructed along the base of the canal structure. The rubble drain was achieved by laying large agricultural pipe, shrouded in geotextile fabric, and connecting it to the existing scour valve outlets in the base of the canal. The scour valve outlets were part of the original canal structure and allowed the canal to be easily drained for maintenance. Over this was placed large concrete aggregate and more geotextile fabric before dirt fill was used to raise the level to approximately 150mm below the level of the canal walls. (Click here to open a separate window showing photos of the construction phase)

The top 150mm of canal wall was left exposed so that visitors to the site can more easily visualise the canal's path and to provide a clear delineation between the natural bushland and the maintained turf that is used between the concrete cycleway and the canal walls.

There are a number of areas along the canal that have not been filled. Some of these areas are to allow visitors to see a larger section of canal and to provide some privacy to low lying neighbours. The other areas are where the canal passes under roads. By not filling these areas the cycleway is able to continue under the roads and therefore provide safe passage for riders of all ages. This is especially noteworthy where the cycleway passes under the busy Cumberland Highway.

By constructing the cycleway through the Greystanes Aqueduct, the one major hill on the reserve has been bypassed, meaning a virtually level cycleway for its full length, a bonus for parents with young children and for those in wheelchairs.

Both ends of the Canal Reserve cycleway are connected to other cycleways which makes a truly exciting cycling/walking network extending across a major part of Sydney.

February 2004 saw the Lower Prospect Canal Reserve gazetted as Crown Land and in a formal ceremony on 15 February 2004 the NSW Department of Lands handed the land to Holroyd City Council (now Cumberland Council) as the Trustee for the Crown Land.

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