Reservoir embankment, tunnel inlet/outlet, valve tower/scour tower
Description
The reservoir complex consists of the embankment; its associated tunnel inlet and outlet from Clarendon, a valve tower and a scour tower.
The embankment was built of earth with a clay core, having a length of 806 metres, height 25 metres, a crest width of 6.1 metres and base width of 125 metres. The volume of the embankment is 546,700 cubic metres, with the original cost of the dam and oulet amounting to 151,000 pounds.
The valve and scour towers are built of stone from Bagshaw's Quarry at Morphett Vale, with ashlar facing Murray Bridge freestone. The valve tower is redundant, but is still operational in the case of an emergency. The scour tower has been recently modified to serve its original purpose.
The tunnel inlet and outlet, which links Clarendon to the Happy Valley reservoir, are constructed of red brick. The orginal tunnel is no longer in use, and has been replaced by a newer tunnel adjacent.
History
The reservoir tunnel was constructed in the period 1892 - 1897 and built by the SA Engineer-in-Chief's Department. The construction of a reservoir at Happy Valley was the outcome of an 1888 Royal Commission appointed to examine water supply in metropolitan Adelaide. In 1891 Mr Oswald Brown (formerly a hydraulic engineer for SA from 1878 - 1882) was requested to return from England to advise on the matter. On 19 December 1891 he proposed the Happy Valley location and following such the Happy Valley Reservoir Act was assented to. The creation of the Act had the effect of linking, in a legislative sense, the Happy Valley Reservoir with the provision for water catchment at Clarendon where water was diverted by tunnel to Happy Valley.
Photo(s) courtesy of: Bruce Harry and Associates (2007)