07/1571 - Response to Information Request [As Published] · 142007.1571

o°

Project 305-2325
February, 2006 . 7 . — : ~ Page 13

 

‘ucti id i

Borehole BH2 was obstructed by boulders, thought to be part of an old seawall
constructed in the past as a shoreline protection wall. Previous investigations carried out
along Hastings Street encountered similar obstructions with boulders associated with the
old seawall at depths of approximately RL 1.0m to RL 0.0m (top of obstruction). These
obstructions are understood to have resulted in difficulties with the installation of steel
sheet piles and have required removal of boulders for some piling operations.

It would therefore be prudent to allow for the likelihood of boulders on this site in the form
of removal of the boulders by excavator. | ,

Should any doubt arise as to the integrity or capacity of the installed piles being affected
by obstructions, compliance testing of piles in the form of integrity testing and/or PDA
testing should be considered.

$4 Slab On Ground

6.4.1 General

Field test results indicate that the existing natural soils, along with any controlled fill, are
suitable for slab on ground construction provided that site preparation earthworks are
carried out in accordance with recommendations in Sections 6.1 and 6.2.

In addition, as noted in Section 6.3.1, the slab on ground floor should be designed to
accommodate the anticipated potential ground surface movement.

6.4.2 Sub-Base

It is suggested that a 150mm layer of sub-base be provided under all concrete slabs. The
sub-base material should be compacted to a density not less than 95% of maximum dry
density in accordance with AS.1289 5.2.1 (Modified compaction). The sub-base is
provided under a concrete slab to:-

* Provide a stable ‘working platform' on which to operate construction equipment;

* Facilitate the provision of a uniform bearing surface under the slab.
Sub-base material should be of good quality conforming to requirements (minimum)
of Material Type 2.4 as specified in the Queensiand Department of Transport,
Standard Specification MRS 11.05, Unbound Pavements (December, 1993).

 

# SOIL SURVEYS ENGINEERING