230132 - 25 Arkana Drive, NOOSA HEADS - Slope Stability Report · EXE23/0017

INTRODUCTION

SCG Consulting Engineers have been commissioned to provide a Slope Stability Assessment for the above
allotment. The assessment considers only the existing state of the allotment and any possible effects that the
proposed works will have on this site.

The proposed works are detailed by Natani Design in plans A001, A101 thru A104, A111 thru A114, A202, A203,
A210, WHS1 and consists of proposed lift shaft and timber deck extension to an existing dwelling.


SITE DESCRIPTION

A desk top study of the site confirms the following:-

   -   A portion of the site is located in an area identified as a ‘Moderate Landslip Hazard’ on the Noosa Council’s
       Landslip Hazard Map.

   -   Reference to the Australian Geological Map 1:100000 Gympie Special confirms the site is located within
       the Coastal Dunes of the late Quarternary Period, consisting of Beach Sands.

   -   Reference to Sunmap 1:25000 topographic maps confirm the site is located on the middle ⅓ of the Weyba
       Ridge.

   -   Level contours provided on the proposed building plans indicate an average fall across the site of 12-20%.
       Maximum grades in the order of 20% occur at the rear boundary.

Field work has been undertaken which included explorative boreholes by Australian Soil Investigations , together
with a walkover of the site by SCG Consulting Engineers.

The borehole logs contained in Australian Soil Investigations report, (No. 33106(S)) confirms the soil profile to
consist of the following –

                            :   LOOSE SILTY SANDS INCREASING IN DENSITY WITH DEPTH

Our walkover confirmed the following characteristics-

Site Slope                  :   A visual assessment of the surface grades within the allotment using a hand held
                                inclometer accompanied with a detailed site survey suggests grades in the order of
                                12-20% exist across the proposed construction site. The measured grades are
                                consistent with the contours indicated on the proposed construction.

Vegetations                 :   Vegetation consists of grasses and scattered trees.

Slope Shape/Location :          The surface profile across the allotments slope faces are generally LINEAR
                                PLANAR.

Drainage                    :   The surface drainage is good, sub-surface drainage is good.         There was no
                                indication of ground water seepage or rising water pressure.

                                Ground stormwater flows from upslope of the allotment are captured by the road
                                reserve.

Earthworks                  :   The existing site has been cut and filled to form level building pads. The existing
                                dwelling is a combination of slab on ground with a small retaining wall around the
                                high perimeter and timber framed floors over the natural profile.

Adjacent Structures         :   Adjacent structures on the neighbouring properties appear to be a mix of slab on
                                ground and suspended timber framed floors/concrete slabs.

Evidence of previous        :   Bent trees.
Soil Movements




 SCG Consulting Engineers                                   2                                   SCG Ref: 33106(SL)