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CLIENT: Westfield Design and Construction
VALUE: $4,700,000
DURATION: June 2005 - April 2006
As part of the Stage 5 Westfield Chermside expansion, Shamrock Civil were awarded the contract for bulk excavation works and the installation of a 530m long trunk drainage system to tie into an existing culvert system and divert water from a creek under the proposed new shopping centre extension (Stage 5), through a twin cell culvert system/sediment basin and drain into Somerset Creek.
The trunk drainage line consisted of 7 No. reinforced concrete structures accommodating a 2.100m dia pipeline and culverts ranging from 3.000 x 2.550m to 4.800m x 3.600m in size. An insitu reinforced concrete base was constructed using traditional methods of construction and the precast culvert elements ranging from 7t to 13.5t were placed sequentially using a 200T crane to allow for deep excavation conditions.
The largest of the structures on the culvert line, headwall 5/1 was a reinforced concrete structure 21 x 22m with 6 No. columns and a sloped base slab which formed a 1m deep sediment basin to minimise the environmental impact on the creek. The original design was a reinforced concrete roof structure but due to continual poor weather conditions, Shamrock Civil put forward a design proposal for the installation of a precast roof. This proposal was approved and 600mm thick precast roof elements were installed covered with a 100mm structural concrete screed.
Working within a live creek environment presented many obstacles throughout the duration of the works, however all critical dates and safety standards were achieved.
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