081128 - Lots 5 - 8 Soil Tests · OPW18/0155

                                 LOTS 5 TO 8, SETTLERS COVE, SERENITY CLOSE, NOOSA




Table 1: Stability Risk Levels
Risk Level                               Example Implications(1)

VH            VERY HIGH RISK             Unacceptable without treatment. Extensive detailed
                                         investigation and research, planning and implementation
                                         of treatment options essential to reduce risk to Low; may
                                         be too expensive and not practical. Work likely to cost
                                         more than value of property.

H             HIGH RISK                  Unacceptable without treatment. Detailed investigation,
                                         planning and implementation of treatment options required
                                         to reduce risk to Low. Work would cost a substantial sum
                                         in relation to the value of the property.

M             MODERATE RISK              May be tolerated in certain circumstances (subject to
                                         regulators’ approval) but requires investigation, planning
                                         and implementation of treatment options to reduce risk to
                                         Low. Treatment options to reduce to Low risk should be
                                         implemented as soon as practicable.

L             LOW RISK                   Usually acceptable to regulators. Where treatment has
                                         been required to reduce the risk to this level, ongoing
                                         maintenance required.

VL            VERY LOW RISK              Acceptable. Manage by normal slope maintenance
                                         procedures.

Note:   (1) The implications for a particular situation are to be determined by all parties to the risk assessment and may
        depend on the nature of the property at risk; these are only given as a general guide.




5.2       Earthworks
5.2.1       Excavation
We understand that the proposed earthworks for the development comprise cutting to depths of up to a
maximum of about 5 m for the basement car park. The toe of the excavation will be setback at least 5 m
from the side boundaries and a minimum of 8 m from the steep dune face. Such excavations should
encounter very loose to loose sand grading to medium dense sand that should be excavatable using
conventional earthmoving equipment.

The sands encountered at this site should stand unsupported at slopes of about 1V:2H in the short-term
provided that groundwater seepage is not encountered and batters are protected from erosion. Given the
boundary setbacks mentioned above, trimming of excavation batters should be achievable at the specified
slopes, however should temporary support be required we understand that sheet piles are the preferred
shoring method.
The use of sheet piles would require consideration of the impact from vibrations on adjacent structures and
underground services. It is recommended that pre-drilling be undertaken to prevent vibration impacts from
sheet piling. A dilapidation survey of adjoining structures and pavements should be carried out prior to sheet
piling. It would be prudent to conduct vibration monitoring, at least during the initial stages of sheet piling, to
confirm the vibration impacts.




December 2008
Report No. 087682058 002 Rev.1                             3