Environmental Engineering Reference
In-Depth Information
Further details of the above are provided in Hunter (1980, 1982) and Hunter and
Hartwig (1962).
Pinkerton and McConnell (1964) describe the performance of the embankment during
construction and its first 2 years of operation and show that it behaved well.
Although it was possible to modify the design during construction and a good result was
achieved, there must have been some cost to the project because the evidence of past slope
movements was not recognised and allowed for during the early planning. It is considered
that adequate evidence was there, but was not found or recognised, mainly because the
question of possible valley-side movements was not addressed. In later projects deep
trenches excavated by bulldozer and ripper have usually been successful in locating the
gaping or infilled joints indicative of this kind of slope instability.
2.10.3.3
Wungong Dam
Wungong Dam is a 66 m high earth and rockfill structure built during 1976-1979 near
Perth, Western Australia. The site is underlain by granite containing several intrusive dykes
of dolerite. The rocks are variably weathered. Lilly (1986) describes landslides which
occurred during construction.
During early site investigations, a rounded scarp was recognised on the right bank
above the upstream shoulder of the proposed dam, and noted as a “suspected old land-
slide” (Figure 2.34). Trenches below this feature confirmed that the ground was dis-
turbed, but the areal extent and depth of the disturbed mass was not determined.
Figure 2.34.
Wungong Dam, plan showing adopted layout and inferred approximate position of old
landslide (Lilly, 1986).
