210533 - 108 Black Mountain Range Road, BLACK MOUNTAIN - Slope Stability Report

Total Concept Homes                                                                                   20332-003-Rev0
                                                                                                         16 June 2022

We have been supplied with architectural layout drawings and elevations (Ref. Hassell Free Designs,
Dwg. No. 01 to 06, dated 22 October 2021) for the project. These indicate that the proposed granny flat
would be located in an area approximately 32 m east/north-east of the existing residence. Ground slopes in
this area are generally indicated to be down to the south-east.

The granny flat would be about 10 m x 8.5 m in plan, consisting of a single storey, relatively lightweight clad
suspended structure, with a sheetmetal skillion roof. Drawings indicate that the structure would be
suspended on steel posts, connected to steel reinforced concrete bored piles (or similar).

At the time of our assessment, some preparatory works had been undertaken, which included an earthworks
pad across the building footprint. This was in the order of about 1.5 m depth of the upslope side; with fill on
the downslope side estimated to be about 1 m to 1.2 m height above the original ground surface.

The property does not have access to mains sewerage or a piped, potable water supply, and therefore
collection of rainwater in tanks and on-site disposal of effluent will be required.

An extract of the supplied drawings is given below in Text Figure 2.




Text Figure 2: Extract of overall layout (LHS); and section through granny flat (RHS), courtesy Hassel Free Designs


1.2    Method and Scope of Investigation
As part of our slope stability assessment, a desk-top study was carried out comprising a review of
published geological maps, aerial photos, and a site classification report prepared by Ground Drill also
prepared a report to address on-site effluent disposal design and feasibility (Ref. Job No. 22/120, dated 24
March 2022).

A walk-over survey was conducted in order to make an appraisal of the general condition of the site in
regard to topography, drainage, vegetation cover, geology, erosion and slope stability and existing
structures. The walk-over survey was carried out by an experienced geotechnical engineer from Tectonic
on 2 June 2022.

The results of the desk-top study and walk-over survey are included in Section 2 below.

1.3    Qualifications of Responsible Engineer
This report has been reviewed by Ashley Davey, an RPEQ with more than 27 years’ experience in
geotechnical engineering, including a number of slope stability projects.




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