J001701-006-R-Rev1_Medihub_Geo

Stockwell



Adequate site drainage should be carried out to ensure that stormwater runoff is directed away from the
building walls and footings. All proposed footings should found such that they are not adversely affected by
any adjacent excavations, batter slopes, trenches, or retaining walls that are not designed to support building
or fill loads. To minimise the potential for any adverse interaction effects, footings should found at least
below a plane extending 1 m horizontally from the base of trenches/batter slopes/excavations/retaining walls,
then rising up at 1V:1H. This requirement is illustrated in Diagram 1.




Diagram 1: Exclusion zone for base of footings.

     6.4 Drainage and Erosion
Site drainage should be designed to readily remove surface water, minimise water infiltration into the slope,
and to prevent ponding of water on subgrade areas during construction and also adjacent to foundations,
perimeter slabs, and driveways once construction is completed.
Roof water, including overflow from rainwater tanks, and water collected from hard surfaces (e.g. driveways)
must be directed by pipes or lined channels to a legal point of discharge.
Shallow subsurface cut-off drains should be installed upslope of building areas in order to intercept and
divert potential subsurface seepage. Diversion drains should be constructed above the crest of any cut or fill
embankments.
Any exposed soil on sloping ground must be protected from erosion (e.g. through re-vegetation).

     6.5 Retaining Wall Design Parameters
Design for basement walls could be carried out using a triangular pressure distribution applicable to the wall
type (i.e. active pressures for a cantilever wall or ‘at rest’ pressures for a propped wall) and based on the
parameters in Table 4 below. These values assume that the walls are fully drained and no allowance is
included for construction loading, adjacent foundation loadings, the effect of sloping ground, or backfill
compaction stresses.




J001701-006-R-Rev1                                                                                 Page 8