GHD is part of the Bulk Water Alliance, along with ACTEW,
ActewAGL, Abigroup and John Holland, commissioned to design and
construct an Enlarged Cotter Dam and secure the Australian Capital
Territory’s water supply for future generations.
The project comprises an 80m high, roller compacted concrete dam
and will be the third largest concrete gravity dam in
Australia.
GHD’s geotechnical team provided investigation services that
resulted in critical inputs into a detailed geological model of the
dam site which in turn informed both dam design considerations and
a range of key construction planning issues. Investigations
included diamond core drilling, down-hole permeability testing,
laboratory testing of rock core samples, seismic refraction
surveys, statistical fracture surveys and detailed geological
mapping.
Due to the steep abutment slopes, helicopters were required to
lift drill rigs onto borehole locations and specialist rope access
techniques were necessary to map outcrops.
The project is now under construction and the excavations for
the main dam foundation are approaching completion, as can be seen
on the accompanying photograph of the right abutment of the dam
site. The placement of roller compacted concrete is due to commence
in late July 2011, with dam completion around
mid- 2012.
Enlarged Cotter Dam, Geotechnical Investigations - Winner of
2009 Engineering Excellence Award (ACT).