Slope Stability Assessment

                   Text Figure 9: Footing depth required to minimise risk of undermining

A suitably qualified and experienced RPEQ engineer must inspect the footing excavations prior to
placement of steel and concrete to ensure achievement of the required depth, founding stratum and
cleanliness.
It will be essential that the foundation contractor have available a ‘mud bucket’ to clean out the pile
bases if bored piles are adopted for deepened footings, such that the recommended founding stratum is
exposed over the full base area and not obscured by ‘fall in’ or other drilling spoil.
If any ground conditions encountered during construction are found to differ from those noted in
Section 2.1 above, Tectonic and ASI should be notified immediately and an inspection carried out to
determine if changes to footing design are required.

4.5      Drainage
Adequate site drainage shall be installed to ensure that stormwater is directed away from buildings,
retaining walls and earthworks batters.
All collected stormwater (including overflow from rainwater tanks) should be taken to discharge a
minimum of 10 m downslope of any structure and earthworks (e.g. cut/fill batters), and not upslope of
any effluent disposal areas. This should be via pipes or lined channels, in order that stormwater is not
allowed to flow down slope in an uncontrolled fashion. Surface dissipation, such as a rock weir or similar,
must be installed at the stormwater outlet(s) to prevent soil erosion.
Subsurface drainage must be installed behind any retaining walls (e.g. slotted ‘aggi’ pipe wrapped in
filter ‘sock’ placed in gravel backfill). Depending on matters such as the extent of drainage installed and
site-specific groundwater conditions, the designer must assess hydrostatic pressure to be accounted for
in the design of the retaining structure. This should be collected and discharged as discussed above.
Subsurface disposal of stormwater must not be undertaken, including (but not limited to) infiltration pits.


5.       Limitations
Your attention is drawn to the document Limitations, which is attached to this letter report.
This assessment relates only to the proposed development as described in Section 1.1.
Please contact the undersigned (given overleaf) should you wish to discuss any of the above matters.




13 February 2026
26020-001-Rev0                                                                                     12 of 13