Laughing Jack Dam, Powers Rivulet
Background
This clay core rockfill dam, completed in 1957, has an internal spillway which allows flood water to flow safely through the rockfill and out of the toe of the embankment. The design, the first of its type in Australia, was proposed by John Wilkins, Engineer for Civil Design in the Hydro-electric Commission. Inside the dam the clay core is protected from erosion by a concrete cap.
This unusual spillway saved the cost of building a separate one on of the dam abutments. Adequate capacity was essential as otherwise large floods could overtop and destroy the dam. This required research into the "flow through" capacity of rockfill. In addition the water flowing out of the embankment could not be allowed to carry stones away with it. To this end large rocks were placed at the toe.
John Wilkins BSc (Hons) FIEAust (1912-1996)
After war experience including airfield construction in Malta, John Wilkins joined the Hydro-Electric Commission in 1950. As the long term head of the Civil Design Division, he was noted for his willingness to embrace innovations which would reduce the cost of civil engineering works. He had a particular interest in soil and rock mechanics and led research into the properties of rockfill.
The principal designer was Geoff Lister supervised by Jack Fidler. The spillway design was verified by hydraulic model tests in a laboratory
Engineering Heritage Recognition Program
| Marker Type | Historic Engineering Marker (HEM) |
| Award Date | March 2001 |
| Nomination Document | Nomination document |
