Development Application Part 2 of 2 - Geotech Report and Plans - OPW13/0816

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 exist      between        static    cone     and        nearby       borehole      GROUNDWATER

 information.                                                                       Where groundwater levels are measured in boreholes,

 Portable     Dynamic Cone Penetrometers                          -
                                                                      Portable      there are several    otehtlal    robletns.

 Dynamic Cone Penetrometer (DCP)tests are carried                                    Although groundwater           may   be     present in lower
 out by driving a rod into the ground with a falling weight
                                                                                    permeability soils, it may       enter the hole     slowly or
 hammer and           measuring          the blows for successive
                                                                                    perhaps not at all during the time the hole is open.
 100mm increments of penetration.                                                    A localized
                                                                                    .
                                                                                                     perched   water table may        lead to   an

 The DCP comprises a Cone of 20 mm diameter with
                                                                                    erroneous indication of the true water table.

 30    degree taper attached to steel rods of smaller                               .
                                                                                     Water table levels will vary from time to time with
 section.
                                                                                    seasons or     recent weather changes and may not be
 The cone end is driven with a 9 kg hammer falling 510
                                                                                    the same at the time of construction.
 mm     (AS. 1289 Test 6.3.2).              The test was developed                   The use of water or mud as a drilling fluid will mask
initially    for pavement           subgrade investigations, and
                                                                                    any groundwater inflow. Water has to be bailed out of
empirical correlations of the test results with California
                                                                                    the bore and mud must be washed out of the hole or
Bearing Ratio have been published by various Road
                                                                                    "revertedft if water observations are to be made.
Authorities.        The     Company has developed their own
                                                                                    More reliable measurements can be made by use of
correlations        with     Standard        Penetration      tests          and
                                                                                    standpipes which are read after stabilizing at periods
Density Index tests in sands.
                                                                                    ranging from several days to perhaps weeks for low
LOGS
                                                                                    permeability soils. Piezometers, sealed in a particular
The borehole or test pit logs presented herein are an
                                                                                    stratum, may be advisable in low permeability soils or
engineering and/or geological interpretation                           of the
                                                                                    where there may be interference from perched water
subsurface conditions, and their reliability will depend
                                                                                   tables or surface water.
to some extent on the frequency of sampling and the
                                                                                    FILL
method of drilling          or   excavation.        Ideally, continuous            The presence of fill materials can often be determined
undisturbed sampling             or core      drilling will enable the
                                                                                   only by the inclusion of foreign objects (eg. bricks,
most reliable assessment but is not always practicable
                                                                                   steel, etc.) or by distinctly unusual colour, texture or
or   possible to justify on economic grounds.                          In any
                                                                                   fabric.   Identification of the extent of fill materials will
case, the boreholes or test pits represent only a very
                                                                                   also depend on investigation methods and frequency.
small sample of the total subsurface conditions.
                                                                                   Where natural soils similar to those at the site are used
The attached explanatory notes define the terms and
                                                                                   for   fill, it may be difficult with limited testing and
symbols used in preparation of the logs.
                                                                                   sampling to reliably determine the extent of the fill.
Interpretation of the information shown on the logs,                               The presence of fill materials is usually regarded with
and its application to design and construction, should
                                                                                   caution   as   the possible variation in      density, strength
therefore take into account the spacing of boreholes or
                                                                                   and material type is much greater than with natural soil
test   pits, the method             of   drilling   or   excavation, the
                                                                                   deposits. Consequently, there is an increased risk of
frequency of sampling and testing and the possibility of                           adverse engineering characteristics or behaviour.            If
other    than   ftstraight       line"     variations      between           the
                                                                                   the volume and quality of fill is important to a project,
boreholes or test pits. Subsurface conditions between
                                                                                   then    frequent test pit excavations are preferable to
boreholes      or   test     pits may vary significantly from                      boreholes.
conditions encountered at the borehole                       or       test   pit
locations.




NOTES RELA TING TO THIS REPORT JUNE 2009.LWP
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                                                                                                         SOIL SURVEYS ENGINEERING