ECM_22343520_v1_Geotechnical Investigation · 132000.200173.1

                                           PROPOSED RENOVATIONS
                                           2 ARAKOON CRESCENT, SUNSHINE BEACH




            Text Figure 13: Footing depth required to prevent undermining

            Site drainage should be designed to readily remove surface water and to prevent ponding of water on
            subgrade areas during construction and also adjacent to foundations and perimeter slabs once construction
            is completed.

            It is recommended that footings be inspected by a suitably qualified and experienced RPEQ prior to
            placement of steel reinforcement and pouring of concrete to confirm allowable bearing pressures and
            cleanliness of excavations.

            If any soil conditions encountered during construction are found to differ from those noted in the geotechnical
            investigation, Tectonic and ASI should be notified immediately and an inspection carried out to determine if
            changes to footing design are required.

            6.3         Temporary and Permanent Retention
            Excavations are anticipated to range up to about 2 m deep. Due to the close proximity to the property
            boundaries, existing structures that are to remain, and surrounding infrastructure, some form of temporary
            shoring may be required.

            Based upon our experience with similar sites, we anticipate that temporary shoring may be achieved by use
            of sheet piles, however Unitywater and Noosa Council requirements for the existing infrastructure may
            restrict the use of sheet piles. Shoring of deeper cuts may require lateral restraint, and this is conventionally
            achieved by helical steel anchors (similar to screw piles). However, the proximity to neighbouring properties
            would require permissions to be obtained for subterranean access. Therefore, where lateral support by
            cantilever only is not feasible, it is suggested that internal struts/propping be considered to provide lateral
            restraint for the shoring system.

            Anchored or propped sheet piles may require pre-drilling to prevent adverse vibrations during sheet pile
            installation.

            Other shoring methods that could be considered include bored contiguous or secant piles. Non-contiguous
            or soldier pile walls are not feasible for the proposed development due to the likelihood that loose sands
            would ‘flow’ through gaps between the piles.

            An advantage of contiguous or secant pile wall retention systems is that they are ultimately used for the
            permanent walls, whereas sheet piles would be temporary to provide retention during construction only,
            therefore requiring a permanent structural wall to be constructed. Bored pile walls generally require greater
            width (horizontally) for installation as compared to sheet piles and are often more expensive.

            The advice of a specialist shoring contractor must be sought regarding feasibility, design and installation of
            the proposed retention system. It will be necessary to conduct numerical analysis to optimise the retention


             24 February 2023
             Report No. 22484-001-Rev0                                17
Document Set ID: 22343520
Version: 1, Version Date: 16/03/2023