This paper describes the design and constructability issues investigated in
the selection of a trenchless solution in comparison to trenched construction
options as part of a scoping study for the augmentation of the existing Bulimba
Creek Trunk Sewer in Brisbane. Initial work involved the planning of alignment
options vis-à-vis ground geology, geotechnical conditions, location and depth of
shafts considering potential construction technology, flotation and stability of
the tunnel, availability of construction sites and the influence of construction
works on neighbourhood properties and the immediate environment.
Two design pipe sizes, DN1200 and DN1500, were considered, and factors
including jacking forces, specification of product pipes, pipe joints, pipe
jacking methods and the associated impacts of ground settlement were carried
out. Of particular interest was research on suitable lubricating fluids with the
potential to minimise jacking forces and maximise the length of pipeline between
launch and reception shafts.