Reference Document - MCU25 0060 (As Published)

It should be noted that during wet weather, the natural soils may cause sediment run-off. Appropriate
erosion and sediment control measures must be installed prior to commencement of earthworks at this
site, particularly given the relatively sensitive eco-receptor downslope.

6.2.2        Excavations
Excavations through the existing soils should be achievable using conventional earthmoving plant (e.g.
small or larger excavators with toothed buckets). Temporary, unsurcharged cuts in the very loose to
loose sand could be formed at 1V:2H and at 1V:1H in medium dense (or denser) sand for batters up to
3 m in height. Flatter batters or temporary retention may be required if groundwater seepage is
encountered or if sloughing of dry sand occurs at the batter surface. Deeper cuts, if required, should be
specifically assessed by Tectonic.
If filling or permanent cuts exceed 1 m, then these must be retained. Permanent cut and fill batters up to
1 m high shall not exceed 1V:2.5H. Any permanent soil and fill batters will require erosion protection (e.g.
revegetation or surface protection).
Given the limited extent of the lower semi-basement level, and offset to properties to the south,
temporary battering may be an option for the southern and western sides of the excavation. The
proximity to the residence to the north will likely result in the need for temporary shoring. Excavations in
close proximity to such existing structures, including on neighbouring properties, will need to be
specifically designed to prevent undermining. It is recommended that footing exposures or confirmation
of foundations via certified building plans be undertaken to assess the possibility of undermining. If
undermining is a potential issue the existing structures may need to be underpinned or excavations may
require temporary shoring.
The advice of a suitably qualified and experienced RPEQ structural engineer must be sought regarding
any potential undermining as well as design and construction of any underpins/temporary shoring (if
required).
The above recommendations do not supersede any existing safety regulations or legislation applicable to
excavations (e.g. limits on personnel entry into trenches).
Due to the highly permeable nature of the sands at this site, stormwater is expected to rapidly infiltrate
the ground, making un-sealed surface drainage ineffective for the control of flows. Any sealed areas
should be graded to ensure free drainage of stormwater away from construction areas, and to a control
point(s).

6.2.3        Filling
The existing sandy soils where free of deleterious materials (e.g. vegetation, building debris etc.) may be
reused as structural fill, subject to appropriate moisture adjustment. It should be noted that compaction
of such relatively ‘clean’ sands as structural fill requires the addition of substantial volumes of water
(‘flooding’) combined with the use of vibratory compaction equipment (typically a smooth drum roller or
heavy vibrating plate).
Should importation of fill be required, it is recommended that such fill should comply with the following:
▪   Minimum CBR of 10%
▪   Maximum plasticity index of 15%
▪   Shrink-swell index ≤ 1%
▪   Maximum particle size of 100 mm


Proposed Residential Development
25 August 2025 | 25038-001-Rev0                                                                             14