RFI - Attachment 4 - Engineering Response Package · MCU22/0171

DME Projects Pty Ltd
P.O. Box 7481
Sippy Downs, QLD, 4556
Tel 0438 157 612
ABN 79 224 274 637

                                          Response to Information Request – 128 Gympie Tce Noosaville
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It is expected that conventional ground support methods will be adequate to ensure the stability of
the adjacent structure(s) during excavation and construction of the basement. A comprehensive
geotechnical investigation has not yet been undertaken to determine the specific properties of site
soils, but it is generally expected that sand/silt and other alluvial soils will be present throughout the
excavation and below the adjoining lots. See below data/image from the Queensland Geotechnical
Database.




                                                                                    QGD Image – Subject Site

Driven steel sheet pile or contiguous pile retaining walls are likely to be the most suitable for this site
(depending on the presence of dense material or rock), but other methods including soil
nailing/diaphragm wall and/or internal bracing options could be suitable, particularly with the
narrow site. Shoring methods that form permanent retaining walls have obvious advantages on this
site with the space limitations and clearances to side boundaries. If dense material or rock is
encountered it is expected to be minimal and rippable. Extensive rock breaking is not expected for
this project.

The site is in close proximity to the Noosa River and tributaries. Groundwater is expected at or
about the depth of excavation and dewatering will be necessary to enable construction of the
basement. Given the narrow width of the site, proximity to the river, tidal influence and the
expected groundwater level relative to the depth of excavation, the dewatering processes should be
limited to managing inflow into the excavation area only; by local drainage and sumps/pumps.
Spears/wells to lower the groundwater beyond the site is not anticipated.

A detailed geotechnical investigation will be undertaken to inform the Operational Works and
building structural designs. We don’t consider the geotechnical conditions on site to be an
engineering constraint that warrants further investigation and cost at the MCU stage of the project.
Furthermore a detailed Acid Sulphate Soils Management Plan and comprehensive dewatering plan