Attachment B Geotechnical report

                                                 4
                                                                                 Job No. DE14/231




3.2    Retaining the Cuts

The cuts can be retained either as:-

       1. If space permits, batter in sand at 30 degrees which would preferably be wet down
          and covered with shotcrete if a steeper cut (say 40) was required.
       2. A thin steel sheet pile vertical wall anchored into the slope, or
       3. A post and panel arrangement or
       4. A permanent concrete piled wall.


Options 1, 2 and 3 allow for construction in front with proper tanking and slope drainage.
Option 4 cannot be sealed properly unless a false wall is constructed in front and slab
drainage protection is formed between the two.

Design parameters for excavations to 5m.
                                                              3
      Loose Dune Sand                  Density       17kN/m
                                       Ka            0.31         Temporary
                                       Ko            0.50         Permanent
                                       Kp            5.0          On benches

                                                              3
      Medium Dense Dune Sand           Density       18kN/m
                                       Ka            0.27         Temporary
                                       Ko            0.43         Permanent
                                       Kp            7.5          On benches

Since the ground above the cuts is level for all practical purposes, and since the swimming
pool beyond the west extremity will be on drilled piles, surcharge loadings on the retaining
walls will be small and a minimum allowance of 10kPa applies.


3.3    Building Support


3.3.1 Shallow Footings

Isolated high level strip and pad footings are not recommended for this site.


3.3.2 Drilled Piles

Because of access restrictions it probably will not be possible to manoeuvre a large tracked
boring rig on this site. A pendulum type auger borer would probably be more convenient if
drilled concrete piles are considered. This matter should be discussed with potential piling
contractors.

Ground conditions will vary south to north over the site from essentially sand (Teewah sand)
to residual clay and sandstone. Dense to very dense sand was not found in BH2 with lesser
strength Teewah sand, clay and extremely low strength sandstone representing this part of
the site.
Drilled piles founding within the medium dense sands at the minimum depth of 15m can be
designed for an allowable end bearing pressure of 1000 kPa and an allowable shaft adhesion
value of 25 kPa below a depth of 2m. If weathered sandstone is intersected the allowable
base resistance increases to 1250 kPa.



Ref 19195B – Markus Hasler                                                 MORRISON GEOTECHNIC
71 Seaview Terrace Sunshine Beach