20220109 - Geotech · OPW23/0182

                             PROPOSED RESIDENCE
                             21 MAHER TERRACE, SUNSHINE BEACH

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 make an assessment of hydrostatic pressure to be
accounted for in the design of the retaining structure.
All excess stormwater collected around the residence (including overflow from rainwater tanks etc.) must be
directed by pipes or lined channels to discharge into the existing stormwater infrastructure along Maher
Terrace. Subsurface disposal of stormwater must not be undertaken.
It is anticipated that a passive (permanent) dewatering system will be incorporated under the ground floor
slab, thus enabling for design without hydrostatic pressure as outlined above in Section 6.5.

7.0      SUMMARY & CONCLUSIONS
Based on the findings of our assessment it is assessed that there would be a Low Risk of slope instability
affecting the proposed development subject to implementation of the recommendations given in this report.



8.0      LIMITATIONS
Your attention is drawn to the document “Limitations”, which is included in Appendix D of this report. The
statements presented in this document are intended to advise you of what your realistic expectations of this
report should be, and to present you with recommendations on how to minimise the risks associated with the
services provided by Tectonic for this project.




16 July 2021
Report No. 21236-001-Rev0                              17