1-22276-01 site plan

Project No. 1-22276                                                                                                                  Page | 25
February, 2020
Ref: 1-22276, 2020-02-28, BR VER 2
Wessel Petroleum Pty Ltd – GEOTECHNICAL INVESTIGATION - Proposed Service Station Reconstruction, 52-54 Mary Street and Weyba Road,
Noosaville




High Level Footings

Given the properties of the founding materials it is recommended that the footings be poured as
soon as possible following excavation, to minimise the potential for desiccation/wetting up of the
founding material. Where the footings cannot be poured the same day as excavation it is
recommended that a blinding layer of concrete, at least 50mm thick, be placed immediately
following excavation, cleaning and inspection of the footing bases.

Where clean sands are exposed at footing base level (depending on excavation disturbance)
the exposed material may need to be damped and compacted.

It is recommended that inspections be undertaken by an experienced and qualified geotechnical
engineer from Soil Surveys Engineering following footing excavations to confirm the adequacy
of the founding soils. Inspections should be carried out prior to placement of reinforcing steel
and ordering of concrete.

Piers/Piles

Difficulty with fall-in may occur with bored piers, particularly when drilling through fill material
and loose natural, and below the water table. It should be ensured that all loose material is
removed from the base of piers prior to pouring of concrete. The use of a 'clean-out' bucket
should be explicit in instructions to the drilling contractor. The practice of 'using water and
spinning the augers' to remove loose material from the pier base is generally unacceptable.

Groundwater was encountered in boreholes (refer Section 5.2) at the time of the investigation.
Should a bored pier foundation system be adopted, some allowance for dewatering and the use
of liners should be made. In addition, it may be prudent to drill a "trial pier" to fully assess
construction difficulties.

Given the nature and strength of the subsurface material encountered, it is recommended that
inspections be undertaken by an experienced geotechnical engineer/engineering geologist from
Soil Surveys Engineering Pty Limited during pier excavations to confirm the adequacy of the
founding material. Inspections should be carried out prior to placement of reinforcing steel and
following cleaning of pier bases.

Driven piles should only be used if vibration will not cause problems to surrounding structures.
Adequate vibration monitoring and control should be carried out.

Some difficulty may be expected with screw piers being installed to levels into and below the
indurated sand layer due to soil strength.

For the driven pile and screw pile options, specialist piling contractors should make their own
assessment of pile founding levels/pile lengths considering pile loads requirements and
subsurface conditions.

Articulation

It is essential that the building be suitably articulated/detailed to allow for ground surface
movement and potential differential movement. Your attention is drawn to recommendations
contained in Section 6.8.

It is recommended/suggested that masonry walls (if any) supported on high level footings be
articulated. This articulation may be achieved by the use of full height (footings to eaves)


                                                                                                            SOIL SURVEYS