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GEOTECHNICAL CONSULTING PTY LTD (GCPL) :
“EXPERIENCE – EXPERTISE & COST EFFICIENCIES” (July 2016)
1.0 GEOTECHNICAL EXPERTISE
Since first registering as a company in 1999, GCPL has provided geotechnical support and
consulting advice to several open pit and underground mines in Australasia. This has covered all
aspects from geotechnical investigations and feasibility studies to due diligence audits and
technical reviews for proposed, new and existing mining ventures. With global exposure and
knowledge of variable ground conditions, GCPL provide optimal excavation and ground support
designs, and practical cost efficient geotechnical solutions.
Having worked on over 100 projects both on site and as a consultant, Ian McEnhill (GCPL director)
has in excess of 25-years geotechnical experience. Over the years Ian has developed a discerning
appreciation of excavation behavior in soil and rock, through experience gained with most mineral-
commodities on a vast range of international projects. Ian has provided support and advice in the
following areas of mining geotechnics :
o Geotechnical Investigation, Rock Mass & Structural Modelling
Planning and supervision of geotechnical drilling programmes;
Geotechnical core logging;
Selection of representative core samples for soil & rock mechanics testwork;
Geotechnical domaining, rock mass characterization & classification - Q, RMR, MRMR,
GSI, Hoek & Brown systems;
Litho - structural mapping, interpretation, 3D-modeling and consideration of structural-
influences on excavation stability;
3D-Modeling and interpretation of site geotechnical conditions;
Numerical stress modeling.
o Open Pit Slope Design & Monitoring
Pit-slope stability assessment and slope design for input into pit optimization studies;
Design of lateral support systems comprising rock bolt, cable bolt, mesh, shotcrete and
fibrecrete support elements;
Blasting trials and optimization to economize on powder factor, achieve required
fragmentation, maintain slope geometry and reduce blast damage to slopes, surrounding
infrastructure and the environment;
Monitoring of piezometric-levels, ground water pressures, slope depressurization and storm-
water drainage management;
Pit-slope displacement monitoring : EDM-prism, Ground-Probing-Radar, SMART-Cables,
Inclinometers & Extensometers.
Waste-dump design & stability monitoring.
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o Underground Excavation Design
Empirical estimation of stable development and stable stope spans;
Identification of least-geotechnical-risk option for portal establishment and optimal alignment
of access declines;
Geotechnical evaluation and selection of most optimal mining method;
Conventional-sink and raise-bored shaft stability / risk assessments;
Stope design and simulation of an optimal stope extraction and backfill sequence so as to
best manage ground conditions and mining induced stress, and to limit potential failure and
dilution;
Modelling and simulation of the anticipated extent of mining-induced rock mass deformation
and strain surrounding underground openings and assessment of the potential for any
propagation and subsidence through to surface;
Assessment of stand-off distance of the decline from the stopes to ensure stability and
access for the duration of mining;
Simulation and design of effective and cost efficient ground support systems for both
development and stopes;
Design and costing of geotechnical monitoring systems to provide advanced warning, and
to closely manage any risk of instability in underground workings (micro-seismic monitoring,
SMART-Cables, MPBX).
o Slope Stability Management and Ground Control Management Plans
Development, implementation and upgrade of Slope Stability Management Plans (SSMP)
and Ground Control Management Plans (GCMP). GCPL have a good working knowledge of
mine-regulatory, statutory and corporate requirements, having developed and implemented
geotechnical procedures, ground control standards, codes of practice and risk management
strategies at many mine sites world-wide.
2.0 PRIOR EXPERIENCE & PROJECTS
GCPL have completed geotechnical investigations, feasibility studies, technical reviews, due
diligence audits and interpretive reporting for the following mining companies in Australasia :
o Placer Dome Kidston Gold Mine (N-QLD);
o OK-Tedi Copper – Gold Mine (PNG);
o AngloGold’s Union Reefs (NT);
o Hill-50’s Mount Marion Gold Mine (WA);
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o Rio Tinto’s North Parkes Gold Mine (NSW);
o Giants Reef Chariot Gold Mine (NT);
o Lihir Copper - Gold (PNG);
o GBS Gold (NT);
o Crocodile Gold (NT);
o Territory Iron Ore (NT);
o Primary Gold (NT);
o Rio-Tinto - ERA Ranger Uranium Mine (NT), and
o Pan-Australia’s Phu Bia Copper – Gold Mine (Laos).
3.0 MINE OPERATION COST EFFICIENCIES and
OPPORTUNITY for GEOTECHNICAL COST SAVINGS
With any project, the primary objective of the geotechnical team is to apply sound, state of
the art geotechnical engineering practice effectively such that the geotechnical risk to the
project, ie - risk to safety, cost and profit – is minimized. In-line with this goal, GCPL’s aim
is to constantly improve safety standards through early identification of geotechnical
hazards, monitoring & management of risk, and implementation of efficient, economic
excavation designs and ground control solutions.
It has been demonstrated that Geotechnical Consulting Pty Ltd (GCPL) possess vast experience in
all aspects of mining geotechnical engineering, providing cost efficient geotechnical solutions for
proposed, new and existing mining operations. With the current commodities slide, the associated
downturn in mining activity and the ongoing increase in marginal operations, (with OHSE the
primary consideration), the need for mining cost efficiencies has rarely been as important as it is
now. In our quest to stay afloat and survive the current turmoil in the market, it is becoming more
vital to reduce costs and seize more opportunity to maximize profit.
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On your project there may well be the opportunity to improve current geotechnical models,
designs, practices, and slope stability or ground control management plans to improve
financial performance.
o Experience and improved knowledge of ground and structural conditions will lead to
a more accurate geotechnical model and result in more reliable geotechnical design
assumptions, and reduced risk to geotechnical hazards. Providing geotechnical
conditions permit, and there are recognized production and / or cost benefits, whilst
maintaining the required safety factors, there may be opportunity to :
o Modify or realign access ramps to capitalize on geotechnical conditions;
o Steepen areas of pit wall to reduce unnecessary waste strip and increase production;
o Reduce pit slope angles and dispense with costly ground support and / or slope
depressurization drainholes;
o Modify blast designs to better-conform with ground conditions. Whilst maintaining required
fragmentation, save on blast hole drilling and explosives consumption, reduce powder
factor, minimize blast-damage to slopes and thereby reduce the need for ground support.
On many mine sites, blast-patterns are standardized throughout, with minimal modification
according to ground and structural conditions encountered. Tighter control is required to
reduce costs;
o Reduce blast sub-drill depths, minimize blast-damage and overbreak to proceeding bench
crests, and thereby reduce the need for ground support;
o Wherever ground conditions permit, substitute blasting with dozer-rip or free-dig. There are
many instances in the industry where contracts are awarded giving the contractor full control
over which areas are blasted and which are free-dig, leading to increased costs to the client
where blasting is often unjustified;
o Dispense with presplit-blasting when ineffective, such as in closely fractured, blocky ground.
o Reduce the size of underground openings and the extent of ground support;
o Adjust ground support type / intensity / pattern / length / thickness to better suite ground
conditions. There are many instances in the industry where standard ground support
systems are implemented (at immense cost) without reviewing and customizing specific to
actual conditions exposed during mining;
o Minimise overbreak and external waste-dilution of ore;
o Introduce more selective and / or optimal mining method/s.
Whilst these are just some examples of where cost-savings could be realised, there may be other
areas where corrections to current design or practice may be made to improve the safety, profit and
viability of your current business venture.
Whilst concentrating on grade, tonnage, CAPEX, OPEX, dollars per ounce, dollars per tonne and
NPV, too often is the need for sound geotechnical investigation, design and practice overlooked by
mining economists. There are many reasons for this. Restricted budget for geotechnical
investigations, limited knowledge of geotechnical conditions, misinformed or incorrect geotechnical
design assumptions, and / or a failure or delay to adjust excavation & support designs to better
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align with ground conditions and stability performance once mining is underway. These are just a
few examples. All too often we see open pit and underground mines being designed and developed
based on limited or outdated models of ground and structural conditions, where there could be
opportunity for more appropriate or optimal design with associated cost savings.
GCPL are currently available to conduct investigations, review and improve your geotechnical
models, designs and practices, and conduct cost-benefit analyses for each of your projects. The
cost of a timely geotechnical review by an experienced professional is often minuscule when one
compares the savings to CAPEX, OPEX and ultimately NPV realized from an improved
geotechnical approach.
What is the geotechnical basis of your current design ?
Check your excavation and support geotechnical design assumptions now with an external
review by an experienced professional.
Please do not hesitate to contact me should you suspect that your project or operation requires
more optimal geotechnical input to improve your mining venture’s financial performance and bottom
line.
Ian McEnhill [email protected]
(Director GCPL)
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Geotechnical Consulting (Pty) Ltd
PROJECT PORTFOLIO
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