003 ECM_22828362_v1_Reference Document - OPW23 0189 · OPW26/0094

                 Logs                                                   for fill, it may be difficult to reliably determine
                                                                        the extent of the fill.
                 The borehole or test pit logs are an
                 interpretation of the subsurface conditions, and       Laboratory Testing
                 their reliability will depend to some extent on
                 the frequency of sampling and the method of            Laboratory testing is carried out in general
                 drilling or excavation.                                accordance with Australian Standard 1289
                                                                        ‘Methods of Testing Soil for Engineering
                 Interpretation of the information shown on the         Purposes’.
                 logs, and its application to design and
                 construction, should therefore take into               Site Anomalies
                 account the spacing of the boreholes or test
                                                                        In the event that conditions encountered on
                 pits, the method of drilling or excavation, the
                                                                        site during construction appear to vary from
                 frequency of sampling and testing and the
                                                                        those which were expected from the
                 possibility of other than “straight line” variations
                                                                        information contained in the report, the
                 between the boreholes or test pits. Subsurface
                                                                        company requests that it immediately be
                 conditions between boreholes or test pits may
                                                                        notified. Most problems are much more readily
                 vary significantly from conditions encountered
                                                                        resolved when conditions are exposed than at
                 at the borehole or test pit locations.
                                                                        some later stage.
                 Groundwater
                                                                        Review of Design
                 Where groundwater levels are measured in
                                                                        Where major civil or structural developments
                 boreholes, there  are   several potential
                                                                        are proposed or where only a limited
                 problems:
                                                                        investigation has been completed or where the
                          Although      groundwater        may   be    geotechnical conditions/constraints are quite
                           present, in low permeability soils it may    complex, it is prudent to have a design review.
                           enter the hole slowly or perhaps not at
                                                                        Site Inspection
                           all during the time it is left open.
                          A localised perched water table may
                                                                        Pacific Geotech would be pleased to provide
                           lead to an erroneous indication of the
                                                                        engineering        inspection services   for
                           true water table.
                                                                        geotechnical aspects of work to which this
                          Water table levels will vary from time to
                                                                        report is related:
                           time with seasons or recent weather
                           changes and may not be the same at           Requirements could range from:
                           the time of construction.
                          The use of water or mud as a drilling           i.    a site visit to confirm that conditions
                           fluid will mask any groundwater inflow.               exposed are no worse than those
                           Water has to be flushed from the hole                 interpreted, to
                           and drilling mud must be washed out            ii.    a visit to assist the contractor or other
                           of the hole or ‘reverted’ chemically if               site personnel in identifying various
                           water observations are to be made.                    soil/rock types such as appropriate
                 More reliable measurements can be made by                       footing or pier founding depths, or
                 installing standpipes from which ongoing                 iii.   full time engineering present on site.
                 monitoring can be undertaken.

                 Fill

                 The present of fill materials can often be
                 determined only by the inclusion of foreign
                 objects (e.g. bricks, steel ,etc.) or by distinctly
                 unusual colour, texture or fabric. Identification
                 of the extent of fill materials will also depend on
                 investigation methods and frequency. Where
                 natural soils similar to those at the site are used




Document Set ID: 22828362
Version: 1, Version Date: 26/02/2024