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

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 TEST LoeA TlONS                                                                     the drilling. The        depth of refusal of the different bit
Test locations (e.g. boreholes, CPT’s, test pits etc.)                               types can provide information as to the st~~r.2~": .}f :!’:’:
Were based oli available access at the time of testili9                              material encountered. Generally two different bit types

(access may need to be provided "by others").                            Test        are   used. The ’V’ bit is a V shaped steel bit and the

locations may have been shifted if access was not                                    ’TC’bit is a tungsten carbide tipped Screw type bit.

suitable.                                                                            Wash Boring       -    The borehole is usually advanced by a

Unless noted otherwise, accuracy of test locations are                               rotary bit with water or fluid pumped down the hollow
to the accuracy of hand held GPS equipment.                                          drill rods and returned up in the space between the

INVESTIGA TlON METHODS                                                               rods and the sailor casing, carrying the drill cuttings,

The    following         is   a    brief summary of              investigation       Only major changes in stratification can be determined
methods currently adopted by the Company and some                                    from the cuttings, together with some information from

comments on their use and application.                                               "feel"    and     rate     of    penetration.          More        accurate

Test Pits            These                             excavated with                information on soil strata is gained by regular testing
                -
                                  are       normally                         a


backhoe                   tracked                                                    and   sampling using            the Standard Penetration Test
               or    a                      excavator, allowing         close

examination of the insitu soils if it is safe to descend                             (SPT)and undisturbed thin walled tube samples (U50).
into the pit. The depth of penetration is limited to about                           Mud Stabilized           Drilling    -    Either Wash            Boring   or


3m for a       backhoe and up to 6m for an excavator.                                Continuous C r           Drilling    an    US        drilling    mud as a

limitations of test pits               are    the   problems associated              circulating fluid to stabilize the borehole.                      The term

with disturbance and difficulty of reinstatement and the                             "mud" encompasses a range of products ranging from

consequent effects on close-by structures. Care must                                 bentonite to polymers such as Revert or BiogeL                         The

be taken if construction is to be carried out near test pit                          mud      tends    to     mask       the    cuttings         and     reliable

locations to either               properly recompact the backfill                    identification    is     only possible from regular intact

during    construction            or   to    design    and construct the             sampling (eg. from SPT and U50 samples) or from
structure so as not to be adversely affected by poorly                               rock coring, etc.

compacted backfill at the test pit location.                                         Continuous Core Drilling             -   A continuous core sample

Hand Auger Drilling                -       A borehole of 50 to 100mm                 is obtained      using    a   diamond          or   tungsten carbide
diameter        is       advanced            by     manually        operated         tipped   core    barrel.        Provided full        core       recovery is

equipment. Refusal                of the augers            can   occur on   a        achieved (which is not always possible in very weak

variety of materials such as hard clay, gravel or rock                               rocks and     granular soils), this technique provides a

fragments and does not necessarily indicate rock level.                              very reliable method of investigation. In rocks, NMLC

Continuous Spiral Flight Augers                        -   The borehole is           coring (nominal 52 mm diameter) is usually used with

advanced                                                                             water flush. The length of core recovered is compared
               using 75 to 300 mm diameter continuous
                                                                                 to the length drilled and any length not recovered is
spiral flight augers, which are withdrawn at intervals to
allow sampling                insitu testing.         This is a                      shown    as   CORE LOSS.             The location of losses is
                         or                                         relatively
economical                     of drilling in                                        determined on site by the supervisor. If the location of
                means                               clays and in sands
above the water table.                                                           the loss is uncertain, it is placed at the top end of the
                                       Samples are returned to the
surface    by the flights               or            be    collected   after    run, when the core is                placed in a storage tray and
                                              may
withdrawal of the augers. Information from the drilling                          recorded on the log.

(as distinct from specific sampling) is of relatively lower                      Standard Penetration Tests                     -
                                                                                                                                    Standard Penetration

reliability due to remoulding, inclusion of cuttings from                        Tests (SPT)are used mainly in non-cohesive soils, but

above     or   softening of samples by groundwater, or                           can       also be used in cohesive soils, as a                       means    of

uncertainties as to the original depth of the samples.                           indicating density or strength.                    The test procedure is

Augering below the groundwater table has a lower                                 described in Australian Standard 1289, "Methods of

reliability than augering above the water table. Various                         Testing Soils for Engineering Purposes"                     -   Test 6.3.1.

drill bits are attached to the base of the augers during



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