Attachment 4 - Site Investigation and Slab Report

                                     BOREHOLE LOG EXPLANATORY NOTES

INTRODUCTION                                                Boreholes are terminated for two reasons.
EBIS Engineering has provided these notes to aid in
the understanding of this geotechnical report and to        1. UTP – Unable to Penetrate. When there is refusal
define the terms and symbols used in our borehole           for the hand auger and it cannot penetrate any
logs.                                                       further due to rock, rock fragments, gravel or hard
Some of these notes may not be relevant to all              clay.
reports.
                                                            2. The soil type is consistent and able to support
SOILS                                                       building foundations. Industry standards generally
Soils exhibit a variety of characteristics which can        recognise two (2) metres as ‘typical’ depth to
change across a site and alter over time.                   termination of boreholes without a limiting layer
Geotechnical      engineering      involves    collecting   (eg rock) for ‘typical’ dwellings.
constrained facts about these soil characteristics in
order to recognize and predict the behaviour of the         FIELD TESTING
soil on a particular site under certain conditions.         There are two main tests which we perform on the
                                                            site.
Description and classification methods for soils and
rocks used in this report are based on the Australian       1. DCP – Dynamic Cone Penetrometer. A rod is
Standard AS1726-1993 and include properties such            driven into the ground using a falling weight
as major soil or rock type, minor soil or rock type,        hammer and the number of drops that it takes the
inclusions, colour, structure, strength, density and        hammer to drive the rod in 100mm increments into
plasticity.                                                 the ground is recorded. Higher numbers indicate
                                                            more stable soils.
SAMPLES TAKEN
Two types of samples can be taken.                          2. PP – Pocket Penetrometer. This is a hand-held
                                                            instrument which is used to measure shear strength
1. D – Disturbed Sample. These samples are taken            and indicates unconfined compressive strength. A
during drilling and provide information on grain size,      number over 100 is acceptable but higher numbers
plasticity,   colour,  moisture    content,    minor        indicate more stable soils.
constituents and sometimes strength and structure.          CLASSIFICATION
2. U50 – Undisturbed Sample. These samples are              Soils are generally divided into two main categories
usually only taken from cohesive soils and are              according to their cohesiveness. After cohesiveness,
performed by pressing a tube with a thin wall and           they are separated by the dominant size of the
50mm diameter into the soil and pulling it out with a       particles in the soil. This is shown on the table on the
section of the soil in a fairly intact state. Strength,     following page.
structure,    volume     change       potential    and      FILL
compressibility are some of the tests which can be          Fill relates to any soil or other material which has
performed using this sample.                                been placed on top of the natural soil. It is sometimes
BOREHOLES                                                   recognised by the inclusion of foreign materials, such
There are several methods for digging through the           as organic matter, metal or bricks, or through
soil to find the constituents that make up the soil type    unusual colour, texture or compaction which varies
in that location. Generally most soil testing by EBIS is    considerably from the natural soil profile.
done by hand auger as this process has the least            The variation in material type, degree of compaction
impact on the location of the testing. Occasionally         and strength of fill materials can differ from the
when necessary, other methods such as drilling with         natural soil and, in some instances where it is
a powered auger, truck mounted drill rig or                 uncontrolled, this leads to a greater possibility of
excavation using a backhoe or excavator may be              unfavourable engineering properties and deficiencies
used.                                                       in performance and possible complications for
                                                            building on the site. The performance of the fill as a
It must be recognised that boreholes represent the          foundation material is dependent upon the depth of
soil conditions in a very small sample of the overall       the fill and the degree of compaction.
subsurface situation and as such the soil profile may
vary across the site. If the soil conditions do appear      Fill can be:
different from those indicated in this report, EBIS         UC – Uncompacted
should be contacted to confirm the requirements.            VC –Variably Compacted
                                                            WC – Well Compacted