Appendix E - Geotechnical Report

                              PROPOSED RECONFIGURATION OF A LOT
                              216 BLACK MOUNTAIN ROAD, BLACK MOUNTAIN

5.3       Laboratory Testing
Table 1 below summarises the results of geotechnical laboratory testing, comprising shrink swell testing on
an undisturbed U63 tube, from the residual clay within the proposed building envelope. Results supplied by
the laboratory are given below in Table 1. The laboratory certificate, with full testing results, is presented in
Appendix B.
Table 1: Summary of Shrink Swell Index Results

               TP No.                              Depth (m)                     Shrink Swell Index (Iss %)

                TP4                                 0.15-0.55                                1.2




6.0      SLOPE STABILITY ASSESSMENT
6.1.1       Existing Conditions
NC mapping (refer Text Figure 7 below) indicates that the majority of the site is within the “Landslide Hazard
Area,” denoted by pink shading.




              Site boundary




Text Figure 7: Extract from NC Landslide Hazard Mapping

It should be noted that the NC mapping is a broad-scale indication of the potential landslide susceptibility
only and is superseded by site specific investigation and analysis works. At the time of our visit, the site
did not exhibit any indicators of significant slope instability. No landslide back scarps, groundwater
“springs,” or areas of naturally ‘hummocky’ ground were observed. The slope below the nominated
building envelope on proposed Lot 1 was noted to be consistent in nature, and mostly linear/planar.

Trees with bent/tilting trunks were observed only in the densely vegetated parts of the gully, and at the
crest of the road fill embankment along the southern boundary. This can be, but not necessarily, a sign of
slope instability.

It is inferred that the inclusion of the site within the “Landslide Hazard Area” is due to the ground slopes
exceeding 15 % (8° to 9°), which in themselves, do not always present a slope instability issue.



19 June 2018
Report No. 17427-001-Rev0                                 6