Reference Document - MCU24/0002 [As Published]

                              www.awgeotechnics.com.au


                            “Normal” classes also have a minimum allowable bearing               have followed AS 2870-2011 soil descriptions contained in
                            capacity as outlined in Clause 2.4.5 of AS 2870-2011.                Clause C2.1 rather than AS 1289 because where there is
                            AS 2870-2011 also has a Class P for problem sites                    a conflict between referenced codes, AS 2870-2011 takes
                            covering fill, soft or collapsing soils, potential slope stability   precedence.
                            problems, mining subsidence and abnormal moisture                    Underslab Termiticide Irrigation Systems
                            conditions. Abnormal Moisture Conditions (AMC) is a                  These are becoming popular and besides serving their
                            particularly contentious area and Clause 1.3.3 of AS 2870-           obvious purpose, they also inject extra moisture beneath
                            2011 covers many situations where this clause applies.               the slab at various times (measured in years). This
                            The most common situations are sites with clay soils                 creates long term “abnormal” moisture conditions that
                            (normally Class M, H1, H2 or E (ys > 20)) that have either           needs to be addressed at the design stage, therefore if
                            existing structures or trees or gardens within the zone of           one of these is proposed for this project, the design
                            influence of the proposed footing. Some of these trees               engineer must be informed prior to preparing the slab. As
                            may be on adjoining properties. Where this clause is                 a general rule, to cope with these systems, the ys must be
                            applicable, we have added further explanatory advice. The            increased by about 50%, which will generally result in a
                            soil shrinkage index (Ips) range quoted in this report was           slab one category higher than would normally be used
                            assigned after considering the guidelines in Section 2 of            (refer P12, Supplement to AS 2870-2011). Upon request
                            AS 2870-2011 and from this we have derived a ys, which               we can supply more specific advice.
                            is the “characteristic surface movement” under NORMAL
                                                                                                 Acid Sulfate Soils (ASS) & Saline Soils
                            moisture conditions.
                                                                                                 Unless specifically stated, we have not considered the
                            Footings designed in accordance with AS 2870-2011 have               possibility of ASS, which occur around the coastline,
                            a           long-term            performance              criteria
                                                                                                 generally below AHD 5.0 and occasionally on broad river
                            and it should be noted that this does not offer a crack or
                                                                                                 flood plains at higher levels. Most Councils maintain maps
                            distress-free performance.          It offers a performance
                                                                                                 of these areas. In new estates the ASS problem has
                            criterion that ensures a low probability of foundation
                                                                                                 normally been assessed and neutralised, but it is
                            failure, provided abnormal moisture conditions, such as
                                                                                                 worthwhile confirming this at land sales, if ASS are
                            over-watering, bad drainage, leaking pipes or nearby trees
                                                                                                 suspected. In older areas, the council is normally the best
                            are not allowed to exist or develop.
                                                                                                 source of advice. ASS, if present, do have the potential to
                            These performance criteria are outlined in Appendix C of             dramatically shorten the life of footings, slabs,
                            AS 2870-2011 and under normal conditions a low                       reinforcement and bricks. This advice is also relevant for
                            incidence of Category 1 damage and an occasional                     saline soils. Unless specifically stated, we have not
                            incidence of Category 2 damage is expected. This                     considered the possibility of Saline Soils, however we can
                            appendix is available from our office upon request.                  provide a quotation to complete this testing.
                            Where Abnormal Moisture Conditions exist and/or are
                            allowed to continue to develop, then not only will the above
                            probabilities increase, but the damage will be greater. The
                            ultimate responsibility falls on the design engineer to
                            negate the effects of these conditions when they are
                            known and for the owner/occupier to ensure that they do
                            not develop. Our responsibility is limited to identifying
                            these conditions.
                            If any potential owner is not satisfied with the performance
                            criteria in AS 2870 (which has been applied Australia wide
                            since 1986) then prior to footing design, he/she should
                            consult with the design engineer and have a specially
                            designed footing more suited to their needs.
                            Classification Limitations
                            The content of this report is based on the expertise and
                            experience of the author representing this company. Our
                            commission didn’t extend to assessing instability due to
                            previous or existing sub-surface mining, landslip or
                            earthquakes, nor did it extend to testing to comply with the
                            relevant contaminated land act or for acid sulphate soils
                            (see note below). If, however any of these exclusions was
                            obvious or where the allotment is within an area where we
                            are aware of a past history of these exclusions, we have
                            made comment and given further advice. This report is
                            based on the assumption that the test results are
                            representative of the true site conditions. Even under
                            optimum circumstances, actual conditions may differ from
                            those reported to exist.          Although our investigation
                            exceeds the minimum requirements of AS 2870-2011,
                            economic constraints necessarily limit the practical extent
                            of any investigation.         We therefore cannot accept
                            responsibility for conditions encountered on this site
                            outside the areas tested which are different to those
                            reported. The positions of these test sites have not been
                            surveyed and should be regarded as approximate. We

                            AWT 77775 Site Classification Report
                                                                                                                                               Page 12 of 17


Document Set ID: 22750694
Version: 1, Version Date: 03/01/2024