Attachment B Eng report

Any material above a 27° line projected from the base of the hill of
slope is considered unstable and totally unsuitable for supporting
any permanent foundations or landscape structures.

The area along the western boundary slopes at approximately 26°
and up to 30° at the north-west corner. The area west and uphill of
the site slopes at a more gentle slope, and is occupied by light-
weight timber residential structures, and a reinforced concrete pool
supported on deep piled foundations.

Our design and suggested construction procedure has taken into
account the critical staged nature of the proposed excavations,
close proximity of adjacent properties (especially the piled pool
structure), the additional soil loadings due to the uphill gradient, the
loose and unstable nature of the upper sand layers (particularly
when vegetation is removed or disturbed) and the limitations of
piling machine size which can access the site.

The key features of our design and construction proposed are:-

e Stabilise surface sands to a depth of approximately 3m, along
BOTH western and south-western boundaries using URETEK
(or similar) ground injection

e Establish survey markers across site and on adjacent properties
for continual regular monitoring during construction

e Install extensive “Sediment/Erosion Control” fences

e Install temporary stormwater collection and disposal system;
install permanent spoon drain and gully pits along west
boundary.

e Avoid ground vibrations by avoiding percussion piling and/ or
compaction.

e Prepare engineered truck turn-around area(s) and access
tracks/ramps

e Construct piled temporary access or engineer-designed cut-fill
access for 50T CFA pile rig and complete the western
contiguous piled walls

e Progressively remove sand east of the new western CFA piled
wall, and construct permanent driveway slab in sections
between the western piled wall and the piled wall on the
seaward side of the driveway.

e Extend temporary access/storage/ramp areas towards north
and back to south-east

e Complete the third CFA piled wall which forms the lower level
platform, and gradually remove the sand to form the lower level
bulk excavation platform

e At all times the retaining walls are fully connected back to the
uphill adjacent wall, drainage is in place, and the CFA piling rig
is operating on stable flat platforms without any risk of slip or
toppling