Friday, 10 June 2011

Why does the water tank stand at Grenfell look strange?

Location and Area History

The many years of work by the residents of the Grenfell area finally bore fruit in late 1897 with the commencement of an inquiry on 20 Decemeber 1897. Over three months later on 28 February the inquiry concluded that the 51 kilometre line should be built from Koorawatha to Grenfell. It subsequently was approved in Parliament and the Act assented to on 24 December 1899. Construction by the Public Works Department had actually commenced the previous month. Additional contracts were let to Messers A Taylor for the supply of timber for the underbridges, and to Messers Espley and Morgan for the bridge piles.
The line was opened on 7 May 1901. Services on the line were based on the connections from the overnight mail at Cowra. General running time from Cowra being slightly over or slightly under three hours depending on whether the train was a Passenger or a Mixed.
Grenfell is 444.947 kilometres from Sydney (via Blayney). Regular passenger services were suspended on 11 August 1974 and all services on the line were suspended from 22 October 1991. The line was subsequently reopened to Greenthorpe (approximately halfway) and this continued to be the case for grain trains only until 2009.
From the opening until the demise of steam two water supplies were provided, one at the junction at Koorawatha and one at the terminus at Grenfell. For a period in the 1960’s an additional standpipe was provided at Greenthorpe.

The tank at Grenfell showing the strange bracing.
The Tank and Dam

On 24 September 1900 Henry Deane, Engineer in Chief signed the plan for a dam on Emu Creek approximately one mile [1.6 km] north of Grenfell station. The area of the dam was approximately 2560 feet long and the length of the dam was 690 feet. The catchment area covered 4.8 square kilometres.
A 3 inch (76mm) pipe was laid from the dam to the station. This pipe was laid on the initially on west side of but after a short distance on east side of Emu Creek in a 10 feet (3 metres) wide easement. Emu Creek runs to the west side of Grenfell Station and with the dam being upstream of the station gravity was used thus negating the need for a pump house.
The pipe then travelled under the railway lines in the loco area to the tank on the eastern side of the tracks. A float valve on the tank controlled the water supply.
A diagram (again signed by H Deane) details all aspect of the tank stand and pipes. The contract for the stand was separate to the actual tank which was the usual practice of the time. The superstructure of the stand was constructed using 12 inch [30 cm] square lengths of timber with 16 piers were sunk into concrete lined pits. These piers were topped by a grid of 12 inch square timbers which supported the tank. Between the horizontal timbers and the tank were 36 cast supports which on which the tank was placed.
The tank of 20,000 gallons (68250 litres) capacity was built with 45 virtually identical 5 feet [1.52m] square cast panels bolted together. The usual practice was to line the bottom of the tanks to assist in their integrity. Concrete was the medium used in the tank at Grenfell.
In the base of the tank is an outlet that supplies a 9 inch diameter swinging jib.
The tank and stand structure at Grenfell was identical to that at Koorawatha and there is surviving evidence on the Koorawatha tank that was the sides were also rendered with concrete. This was not the usual practice.
In early 1946 the tank failed, the details of the failure not being known. With no other water facility on the line locos (generally members of the 30T class with 3650 gallon tenders) could not run from Koorawatha to Grenfell and return without running out of water and a replacement was required. The opportunity was taken to assess the actual requirements and it was found that a tank of similar size was not required. This was because under normal circumstances there were a maximum of two locos at Grenfell at any one time and combined their maximum tender capacity was less than than 7500 gallons.
A drawing was issued on 1 March 1946 showing the new tank and plumbing arrangements. The Railway’s had stocks of the panels used to construct the tanks and these were used for the new tank. The original stand was still serviceable but was bigger than the new 10,000 (40,000 litre) tank required. As such the number of piers was reduced to nine and the surplus piers removed. The cross-bracing was reused and shortened to fit. A new swinging jib was also provided. The unused portion of the stand was recovered on 19 February 1947.
The tank also supplied a 3 inch stand pipe located beside a nearby road.

The outlet structure from the dam to the water tank

Looking along the dam wall from west to east - the station is apporximately 1.6km to the right.
The base of the tank stand showing the no longer required foundations.
The front of the tank showing the swinging jib. Note the angle of the timber bracing and the unused holes in the vertical posts.

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