slope stability · MCU22/0172

Integra Partnerships                                                                          22339-001-Rev0
                                                                                           13 September 2022

2.2    Topography
During the site walk-over, topographic features specific to the site were noted, and ground slopes were
recorded using a hand-held clinometer. As illustrated in Text Figure 4, the site is located on the south-
westerly facing flank of an ancient sand dune, which crests about 300 m to the east.
The natural surface profile at the site had been interrupted by historic landscaping and residential
construction. Based on a visual inspection it appeared that cut and fill earthworks in the order of about 1.5 m
depth/height had been previously undertaken, most of which were supported by retaining walls or structural
residential walls. The existing residence was a single storey building terraced into the natural slope.
The natural ground slope was measured to be about 9° at the rear of the property. The slope from the front
of the existing residence to the road was measured at the time of our assessment to be about 15°. A brick
retaining wall up to 0.7 m height was located immediately upslope of the footpath and a blockwork retaining
wall up to 1.3 m height was observed in the courtyard just behind the existing building that extended across
the width of the property. To the west of the property on Grant Street, splitting the north and southbound
lanes, a grouted rock retaining wall was observed, approximately 3 m height and sloped at 1 in 1.




                                              Subject Site




Text Figure 4: Ground surface contours, 1 m spacing (courtesy NC interactive mapping)

Site conditions at the time of our investigation are shown in Text Figures 5 to 8 below and on the following
page.




Text Figure 5: Panoramic view west across the existing residence




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