35484 Approved Plans Ba · MCU21/0222.01

Although we consider the allotment stable in its current form there will always be a risk of landslip under severe
stormwater conditions.

Measures that will reduce this risk include the following but are not limited to.

The finished ground surface should be leveled and graded to ensure no concentration of stormwater runoff
leading to ground scour can occur.

Any collected stormwater from areas other than the roof should be disposed of downslope from the proposed
dwelling and should also ensure no ground scour can occur.

All stormwater runoff from hard landscaped areas should be directed around the perimeter of the house and
contained within the site via diversion bunding, scour proof drains and field inlets. Stormwater runoff from roofed
areas should be disposed of via piping to the soakage pits located downslope of the dwelling.

All stormwater collected from roofed areas should be directed to storage tanks for re-use. Overflow from the
tanks should be disposed of via rubble soakage pits downslope of the dwelling.

It should be noted that concentrating stormwater infiltration into soil profiles can lead to instabilities in moderately
sloping areas. For this we recommend numerous soakage pits to be provided across the allotment. They should
be located away from any structure where ground instability could lead to damage.

No stormwater runoff should be allowed to flow over any exposed excavated embankment faces or filled batters.

All existing cross allotment flows from neighbouring properties must also be considered, managed and
maintained. Clear unhindered drainage paths must be provided and maintained during and beyond construction.
All constructed retaining walls must have effective drainage measures upslope and beyond the walls to relieve
any sub-surface water pressure/build-up. These drains must be maintained and flushed out regularly. To achieve
this we recommend bringing the upstream end of the drain to surface and capping off to allow future flush out.

We have attached guidelines for hillside construction extracted from Australian Geomechanics vol. 35 March
2000 — “Landslide Risk Management’. These references provide commentary on good design and building
practice.

We trust this meets with your requirements, however should you have any queries on the above matter please

contact the undersigned.

Yours faithfully
~

Sean Richardson RPEQ 5835
For and on behalf of
SCG CONSULTING ENGINEERS

Encs AppendixA - Some Guidelines for Hillside Construction
Appendix B - Landslip Mechanisms
Appendix C - Landslip Risk Assessment Matrix

SCG Consulting Engineers 5 SCG Ref: 32027(SL)