08/0169 - Response to Information Request [As Published] · 132008.169

From the proposed building plans and survey information the construction of the garage floor level will
require a cut in the order of 2.6 - 3m below the existing surface level adjacent the southern boundary.
For this to be achieved a cantilevered or tied cantilevered retaining wall must be installed. We
recommend that either augered secant or contiguous concrete pile systems be used to achieve this.
The use of driven sheet piling is not recommended in this area. Pre-Augered and pushed in sheet piles
would be an acceptable alternative.

The design of the retaining system is to be by a specialist contractor and must consider surcharge
loading from sloping embankments above the structures.

Vegetation removal should be minimised. As soon as possible after construction, dense, deep rooted
native vegetation cover should be propagated on any exposed surface in order to stimulate and
improve the binding properties of the natural vegetation.

7.4 Stormwater

All stormwater collected within the allotment must be disposed of in a manner that does not
compromise the stability of the site. Where possible roof drainage must be directed to and disposed of
via the access easement that serves the allotment. All other stormwater including surface runoff must
be collected via approved means and stored in tanks for re-use. Overflow from the tanks should be via
infiltration pits to minimise surface flows and scour. We have compiled a stormwater drainage plan
detailing these proposals and attached a copy to this report (Drawing No. 19064-SW1).

8.0 CONCLUSIONS:
Based upon our findings and recommendations we believe the allotment in its current state is stable
and would support the residential construction within the scope of the current proposals and AS 2870-

1996.

The use of vibrating earthwork equipment used for driving piles is not advised within the allotment. Mini
excavators or similar excavation equipment would be acceptable for use throughout construction.

Any removal of existing vegetation should be followed by reinstatement of deep rooted native
vegetation common to the area.

Measures to prevent sand migration during construction must be implemented. These must protect
against wind blown and fluid (runoff) migration of the sands.

Foundations must be designed in accordance with AS2870-1996 and accepted engineering theory.

9.0 DOCUMENTATION:

In preparation of this report we have considered architectural and survey information contained within
the proposed architectural plans as provided by Noel Robinson Architects and a site survey plan by Lau
Surveys (No 6611-DT]).

10.0 STANDARDS AND REFERENCES:

The standards and references used in compiling or referred to in this report are as follows:
AS 1726-1993 Geotechnical Site Investigations

AS 2870-1996 Residential Slab & Footings Code

AS 1289 Methods of testing soils for engineering purposes
AS 3798-1996 Guidelines on earthworks for commercial and residential developments.

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SCG Consulting Engineers 4 SCG Ref: 19064(S)