Cethana Dam
Background
The Cethana Dam was completed by the Hydro Electric Commission in 1971 forming part of a series of seven dams and hydro electric power stations that comprise the Mersey Forth Power Development.
Cethana is a high concrete faced rockfill dam and its design solved the problem typical of this style of construction - large leakage through or around the concrete face.
Being sited in a narrow gorge, Cethana dam was planned to be a concrete arch dam, but when an adverse jointing pattern was revealed in the abutments, a concrete faced rockfill design was adopted.
This innovative design of minimising leakage from the concrete faced rockfilled dam was adopted internationally.
Equipment and Subsequent History
To minimise leakage the rockfill was well graded, placed in layers, wetted and compacted with vibrating rollers to reduce settlement.
The rockfill was completed to crest level before placing the concrete face began.
Each concrete face slab was slipformed from bottom to crest level in one pour without stopping. The longest pour took 3 days.
Waterstops between face slabs were embedded with great care. Two waterstops were used in the point between the face and the plinth.
The compaction of the rockfill and the elimination of horizontal joints in the face slab contributed to the minimising of leakage.
The dam is 110m high and the water feeds an underground power station. The power station contains a single 100MW Francis turbine.
There are a further six power stations utilising the waters of the Mersey, Forth and Wilmot Rivers to generate power.
Engineering Heritage Recognition Program
| Marker Type | National Engineering Landmark (NEL) |
| Award Date | 2001 |
| Heritage Significance | One of 25 Australian dams with the highest heritage value. First successful high concrete face rockfill dam with minimal leakage. |
| Nomination Document | Available here. |
