Slope Stability Assessment

Paul & Janelle DeSouza                                                                          22198-001-Rev1
C/- Sarah Waller Architecture                                                                      25 July 2022

Ground Drill has classified the site as Class P strictly in accordance with AS2870-2011 due to poor
bearing capacity and trees. However, they go on to state that were it not for this, the site would exhibit the
characteristics of a Class H1 site, with estimated characteristic surface movements (ys) ranging from 41
mm to 50 mm.

2.3     Topography
On the wider scale, the site is located within an area of relatively high relief, moderately steep, rounded
spurs and knobs. These are cut sporadically by relatively wide and flat bottomed creek valleys.

The eastern allotment boundary generally follows a rounded ridgeline (over which the access traverses),
rising to meet the knob upon which the residence is proposed in the north of the block. Ground generally
slopes to the west through the allotment, towards a creek valley as mentioned above.

Ground slopes were recorded using a hand-held clinometer during our site walk-over. The residence is
proposed to be sited just to the north of the crest of a well rounded knob, with ground slopes extending
north-east, north and north-west. The rounded crest featured slopes of about 10°, increasing downslope to
12° to 16° to the north and north-west; although in excess of 22° just off the proposed south-eastern edge of
the building footprint.
At the proposed shed location, ground slopes extended to the north-west at about 10° to 14°.

While the knob was rounded, the slopes were generally quite consistent, with slightly divergent to linear
ground observed. No irregular or ‘hummocky’ ground was seen at the time of our field assessment.

Text Figure 4 below gives an overview of the topography of the site.



                                                         Lot boundary

           Approx. house site




                                                               Approx. access route




      Low lying ground
      associated with larger
      creek drainage




Text Figure 5: Image showing ground surface contours at site and surrounds (courtesy NC)

Text Figures 6 and 7 on the following page give an indication of the ground conditions at the site at the time
of our walkover inspection.




                                                        5/13