Srknews46 Mine Water Managment a4 Lr

7/29/2019 Srknews46 Mine Water Managment a4 Lr

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Mining personnel have a dierent interpretation o the term mine water management. For the rock

mechanics engineer it is the de-pressurisation o a slope in an open pit, or the metallurgist it might

pertain to the water contained in the process circuit, and or the tailings engineer, the waste circuit.

Our perspective

No. 46

SRK ConsultingsInternational

Newsletter

In this newsletter we have used the term in its

broadest context to mean water impacted by

the mining project, the impact o water on the

mine, and the water managed within the greater

ootprint o the site.

We believe the management o water on a mining

project will become ever more important in the

uture. In arid areas water is a scarce and expensive

resource to the extent that some projects will stall

because o a lack o water or because the cost

o supply will be prohibitive. In high rainall areas,

the containment o contaminated water might not

be possible without large structures and transer

systems, whose construction and operating costs

will again be large. Treatment o water, both as

supply and beore release to the environment, has

historically been expensive. Added to this is the ever

increasing regulatory environment, which mightmake discharge impossible.

Water issues should be considered in an

integrated way during design, start-up, operation

and closure o a mining project. During design,

ailure to integrate the various components can

signicantly underestimate the time and cost o

implementation. During start-up, extreme climaticconditions, unplanned during design, can cause

fooding o construction works and initial pits or

require additional water supply. Operational issues

could include incorrect estimations o plant make-

up water, or tailings circuit imbalances or changes

to the volume and quality o water as process

plants expand or change process technologies.

Closure o any mine will include pit lake hydrology

and chemistry, runo rom rehabilitated dumps

and residual contamination o plant areas,

amongst the issues o concern.

continued

Open pit partially fooded ater a heavy storm

news

Mine water management


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Artesian borehole

Or prsp (continued)

We have addressed many mine water

management components in this

newsletter, including the supply o water

in arid areas, the protection o sources,

depressurisation o pit slopes, water

balances, storm-water management,

water chemistry and last, but not

least, disposal. We have tried to show

where integration can save costs, in,

or example, the use o boreholes or

both hydrological and geotechnical

purposes. We have showcased projects

rom various regions in the world.

Some o the tools we use, including

water balances, salt balances and riskassessments, are also discussed.

The partially fooded open pit in

the picture is the result o poor

implementation o storm water

controls, and will lead to major expense

in rehabilitation, as well as signicant

loss o production, and could have

been avoided with due care.

Richard Connelly: [email protected]

Brian Middleton: [email protected]

Proposed West Wall cutback layout in 3D

The Ok Tedi copper-gold mine in

Papua, New Guinea is situated withina seismically active, mountainous

region o extremely high rainall.

The current open pit is transected

by several large aults, and the rock

mass conditions are complex. Material

permeabilities are variable, with

considerable contrast within the major

rock types and ault zones. The pit is

being progressively deepened with

ongoing mining, and a cutback o the

West Wall is being considered, which

would result in a nal wall height o

nearly 1000m.

The main actors aecting the stability

o the West Wall cutback are:

the quality of the various materials

within the wall

the position and nature of major

structures

the pore water pressure distribution

behind the wall

O these actors, only the pore pressure

distribution can be adjusted to enhance

RichaRd cOnn elly

Richard ConnellyMSc, C Eng,

C Geol, and Principal

Hydrogeologist in

SRKs Cardi oce,

has over 40 years

experience in mining

hydrogeology

and engineering

geological aspects o groundwater and

water supply. He specialises in mine

dewatering and slope depressurisation,

water supply, groundwater pollution, acidmine drainage, groundwater recovery

ater closure and environmental audits.

Currently, he is helping to develop

integrated teams o SRK experts in water

management to provide best possible

services to clients.


B R i a n m i d d l e t O n

Brian Middletonis a corporate

consultant in SRKs

Perth oce. For

the last 35 years,

he has been

involved in design,

management and

peer review o water

projects. These projects include three

major studies o the water resources o

South Arica, undertaken or the Water

Research Commission over the last three

decades; the 65m high Ceres Dam; an

environmental liability evaluation or a

large chemical company; and numerous

water management projects or mines

and industrial complexes in many parts

o the world.

Brian Middleton: [email protected]


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drg srs or srg sb

o propos b O t

Horizontal drainholes being drilled into the Ok Tedi West Wall

stability. In discussions with the client,

SRK devised a phased modellingapproach to assess the stability o

the cutback design or the West Wall,

and to investigate passive drainage

requirements for ensuring stability.

The modelling involved an iterative

series o numerical analyses to

assess the eectiveness o a range

o drainhole designs with careully

selected spacings and lengths.

The phased modelling approach

included the ollowing steps:

1. Initial slope stability analyses o two

sections, using small-strain nite

element analysis (Phase2 sotware)

to determine the approximate

position o the groundwater level

(i.e. distance behind the ace) and

the pore pressure distributions

required to maintain an acceptable

actor o saety within the West

Wall cutback design.

2. Unsaturated 2D and 3D nite

element fow modelling, using

FEFLOW sotware, to determine

the drainhole congurationsrequired to achieve the pore

pressure distribution that the

initial Phase2 modelling indicated

will allow or a stable West

Wall cutback. Identiying these

requirements allowed the client to

assess whether it was possible to

implement the necessary drainage

requirements within the time

periods under consideration during

the cutback.

3. Conducting conrmatory Phase2analyses, using the results rom

the FEFLOW modelling to provide

better groundwater inputs and

to conrm the lateral (i.e. out o

section) spacing o drainholes

required to maintain suitable wall

stability. SRK perormed the lateral

spacing assessment using the

groundwater conditions in sections

halway between the drainholes,

as the 3D FEFLOW modelling

indicated.

i a n d e B R u y n

Ian de Bruyn hasover 15 yearsexperience in

the geotechnical

engineering eld,

over a wide range

o projects in both

the mining and

civil engineering

sectors. He has strong expertise

in geotechnical assessment and

in providing design parameters or

open pit mining operations. He has

worked on projects involving verylarge pits in challenging rock mass

conditions. Ians projects have involved

site investigation, characterisation,

analysis, evaluation, design, risk

assessment and reporting at all levels

rom conceptual through pre-easibility,

easibility and working design.

Ian de Bruyn: [email protected]

Based on the approximate expectedmining period o the West Wall cutback,

our excavation stages o one-year

periods each were dened or this

modelling exercise. Horizontal drains

were activated sequentially in the model,

together with the excavation sequence

to simulate the proposed mining. The

drainage designs required to maintain

stability o the current cutback design

at a suitable actor o saety were

identied.

Ian de Bruyn: [email protected]


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Installation o groundwater monitoring borehole

dsgg progrs o s

pr o growr

systems hydraulically. In open pit

mines, slope stability can be aectedi groundwater seeps into sensitive

slopes, thereby reducing stable slope

angles or necessitating dewatering

costs. In underground mines, hydraulic

connection can lead to infows and

higher pumping and treatment costs.

The solution is to develop a preliminary

understanding o the groundwater

system integrated with a good

exploration drilling management plan

to ensure that boreholes are properly

sealed ater data collection i theseleakage risks are present.

Environmental protection. When

investigating sites such as waste dumps,

tailings acilities and leach pads, special

care must be taken to avoid opening

up pathways or contaminants through

investigation and exploration holes.

In recent years, SRK Ankara used many

exploration holes or hydrogeological data

analysis. At one o the largest gold mine

projects (Koza Gold) located in WesternTurkey, geotechnical drills with depths

ranging rom 200-400m were used.

Important eatures were tested using

Agood understanding o mine

water management issues relatedto underground and open pit mines

depends on collecting a comprehensive

hydrogeological data set. Data collection

is the most time-consuming and

costly stage since it requires gathering

substantial amounts o long-term

seasonal data. With this data available,

a conceptual model can be constructed

and subsequently converted into

a 3-dimensional numerical model

to simulate and evaluate the mine

development.

Where possible, SRK recommends that

clients use exploration and geotechnical

boreholes or hydrogeological purposes;

this approach has many advantages.

Exploration holes can be used or

hydrogeological and environmental data

collection, producing large savings in cost

and time. Besides these advantages, it is

possible to save on operational costs and

protect the environment.

Operational cost savings. Drilling

exploration holes can have adverse

eects on mine development because

they can link dierent groundwater

GOktuG ev in

Goktug Evin is asenior Hydrogeologistin the SRK Ankara

oce with over

8 years o experience.

He specialises

in groundwater

fow, aquier

characterisation,

including aquier tests, 3D groundwater

and transport modelling o both saturated

and variably saturated media. Goktug

has experience in GIS, remote sensing

and spatial analyses. His mining projectsinclude supervising hydrogeological site

investigations, optimising dewatering

systems, mine water supply and

management and pollution control.

He has worked on large-scale mining

projects in Turkey, and on environmental

and easibility studies in northern Europe,

Kazakhstan, and Saudi Arabia related to

mine dewatering, pit depressurisation

and pit lake hydrology.

Goktug Evin: [email protected]

P e t e R S h e P h e R d

Peter Shepherd isa Partner, Director

and Principal

Hydrologist in the

SRK Johannesburg

oce. Having

completed his BSc

(Hons) in hydrology

at the University oNatal, he has been with SRK since 1992.

His specialisations include foodlines, dam

hydrology, mine water management, river

hydrology, water supply, strategic water

assessments and food management.

Peters recent mining projects were based

around South Arica, as well as in the

Democratic Republic o Congo (DRC),

Botswana, Mozambique and Zambia.

His project work has ocused on fow

monitoring, return water dams, stormwater

control and mine water master plans.

Peter Shepherd: [email protected]


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packer testing and holes were converted

to piezometers to monitor phreatic levelsor groundwater response during pumping

tests. At the Kslada gold mine project,

which will be the largest open pit mine

in Turkey, a total o approximately 3000m

exploration drills were utilised or hydro

testing; a total o 100 packer test and

airlit tests were conducted and holes

were converted to piezometers or long

term monitoring. For another easibility

study, the Yenipazar project, where a

total o 1700m o exploration holes were

converted to piezometers to monitor

groundwater levels, the precise shape o

the piezometric surace was modelled in

a very early phase.

SRK advises mining clients to consider

using all types o boreholes, particularly

those developed in the early stages

o a project or characterising the

groundwater system. A properly

structured and managed approach to

borehole development can result in an

ecient, environmentally-sound and

cost-eective hydrogeological datacollection program.

Goktug Evin: [email protected]

Research done in South Arica showsthat change in the global climate is

aecting the way local mines need to plan

and build their inrastructure, particularly

when it comes to water management.

Studies by Lumsden and Schulze show

climate change is going to make the

eastern parts o SA signicantly wetter,

and western regions drier. In the eastern

areas o the country, this means mines

will experience a disproportionate

increase in the amount o water that spills

into the environment, while mines in the

western parts will need to manage their

water resources with greater care.

Managing the on-mine water balance

in drier areas is going to call or

better re-use strategies, including

continued improvement in the design

and implementation o ways to keep

water within the mine boundary, and

to limit the amount o clean water that

mines procure rom municipal or other

sources. Rustenburg Platinum Mines

have already taken steps to reduce the

amount o water abstracted rom thepotable water system. Initially, their

allocation o water was greater than

50Ml/d but, ater implementing water

saving strategies, the actual potable

water abstraction was reduced by

30%. Additional water saving strategies

will reduce the potable water use by

a urther 20%. Not only is this reuse

o water allowing the mine to expand

operations, it is also allowing additional

growth in the Rustenburg area.

In areas where more rain is predicted,

mines ace the prospect o breaking the

law i their inrastructure cannot limit

mine spillage into the environment.

Facilities in these areas must be

designed or modied to comply with

the new parameters that climate change

brings. The Amandelbult Mine has

implemented stormwater controls to

minimise the mixing o clean and dirty

water so that even under signicantly

higher fows, the risk o fooding will

be minimised. With food hydraulics,

doubling o the fow does not double

the size o the canal; the addition caneasily be managed with a bund about

500mm as the Amandelbult area has

proved, i.e. it is not necessary to double

channel size; new food fow can oten

be met with nominal increase in height

o containment wall.

Using the Lumsden and Schulze

research, SRK scientists Phillip Hull and

Hediya Ghassai predicted that a 40%

increase in rainall could more than

double the amount o contaminated

water a mine spills into the environment.As an example o this, a return water

dam in the Eastern Limb area o South

Arica must be built 30% larger than

needed under present climatic conditions.

Mines are starting to include climate

change in their design but need always to

keep in mind the implications o climate

change or their site inrastructure.


cgg s pg So ar

Water supply or mines in arid regions will become even more important in uture


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Proposed mine site

The design o a mine water control

system depends on many actorsincluding:

hydrogeological conditions

dewatering or depressurisation

requirements

start, duration and rates of pumping at

dierent stages o mining

interaction of pumping infrastructure

with mine planning and operations

availability of drilling and pumping

equipment

contractor experience

capital and operating costs

production schedule for life of mine

The proposed mine site is located in

Western Australia along a steep ridge.

The ridge is made o steeply -dipping

banded iron ormations (BIFs), or iron-

rich sedimentary rock, interlayered with

elsic sedimentary and igneous rocks

that host the iron ore mineralisation.

The sub-vertical, high permeable BIFs

act as a groundwater storage system.

Water fows within a tailings dam and return water dam

mgg s s wr

A water balance model is commonlyused in the mining industry to monitor and

manage the distribution o water within

a mine; however, it is also vital to keepan eye on levels o salt in on-site water,

especially as mine water is increasingly re-

circulated in the interests o conservation.

Water balance development is a core

strength across all o SRKs global oces

and water balance methods have been

developed or every continent.

Mines use a water balance model to

establish losses and determine how much

inow is required, mainly, to replace the

evaporation and seepage rom tailings

acilities and return water dams. As minescomply with increasingly stringent water

conservation regulations, they increase

the amount o water that is re-treated and

retained or use in the process plant.

This trend has generally had a positive

impact on the levels o discharge

rom mines into their surrounding

environments. The downside o this

process, however, is that the salt level o

on-site water rises steadily when it is not

diluted by proportionate amounts o clean

water rom outside sources.

Under these conditions, certain dangers

are introduced to the mining circuit:

As the plant is designed for a certain

minimum water quality, it may not

operate optimally i salt levels impair this

quality beyond a certain point

High salt levels will corrode most

metal components in a circuit, raisingoperational and replacement costs

Steadily increasing salt levels will turn

water into a brine that needs specialised

removal rom the site as a hazardous

material

Salt balances developed or the

Rustenburg area have seen the total

dissolved salts (TDS) increase rom

about 1000mg/l ten years ago to about

4000mg/l, due mainly to eorts to reuse

as much o the water as possible. This

increase in TDS does not materiallycorrode the steel pipes but has been

included in uture budgeting and long-term

replacement o steel inrastructure. Water

treatment plants have been installed at

Amandelbult mine to remove the salts

and the water is used as potable water to

reduce the mines reliance on the already

strained potable water supply to the area.

SRK employs a range o tools to monitor

and control salt levels in mine water rom

a simple spreadsheet-based method that

a mine can employ without specialist

skills, to purpose-designed computer

models that are more complex and costly.


Luke Esprey: [email protected]

WATER FROM SLURRY

EVAPORATION

EVAPORATION

WET BEACH

POOL

RAINFALL

DRY BEACH

SEEPAGEPLANT

TAILINGS DAM

DAY WALL

INTERSTITIAL

STORAGE

SPILLAGE OR CONTROLLED

DISCHARGE TO NATURAL

WATER COURSE

SEEPAGE

RETURN

WATER DAM

SPILLWAY


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Wr oro o or

ro or proj asr

Mining will take place below the water

table. The pit water control systemmust deal with the stored groundwater,

rainall recharge and the lateral

groundwater recharge through un-

mineralised BIFs, palaeochannels and

open aults that cross-cut the area.

Based on the geometry o the

ormation and the design o the

open pits that develop wider and

deeper with time along the ridge,

in-pit dewatering boreholes, along

with interception boreholes located

outside the pit perimeters, wererecommended or the project. In-pit

dewatering boreholes can interere

with the mining operations and aect

the mines eciency. In order to

minimise potential intererence and

support decision-making on the water

control strategy or the project, an

analysis was undertaken or several in-

pit water control options. This analysis

considered the location and orientation

o potential boreholes, their longevity

and replacement requirements,the estimated cost or each option,

and the operational considerations

during installation and operation othe system based on regional drilling

experience and regional mine water

control implementation. Next ollowed

a qualitative risk assessment related

to the planned dewatering system

involving all stakeholders (project

mining manager, project engineer,

master driller, open pit mining

engineers). The objective o the risk

assessment was to categorise the

possible implications and uncertainty

associated with the design, provide

detailed control measures or each

identied risk and dene residual

risk ater the control measures were

implemented.

Using the above approach, SRK was

able to present a recommended

water management strategy or the

project that met the requirements for

dewatering and the mining operations

in the most cost eective manner.

Sylvie Ogier-Halim:

[email protected]

Sylvie OGieR-hali m

Sylvie has over10 years o

experience in

environmental

geochemistry and

hydrogeological

projects in France

and Australia.

Her expertise

lies in contaminants, groundwaterinvestigations, extensive eld sampling,

and modelling. Since joining SRK Perth

in 2008, Sylvie has been involved in

geochemical and hydrogeological site

assessment, developing hydrology

and groundwater investigation

requirements or iron ore, copper, gold

and coal seam gas projects, eldwork

supervision, conceptual and numerical

modelling, risk assessment, closure cost

estimation, reporting and due diligence.

Sylvie Ogier-Halim:[email protected]

luke eSPRey

Luke is aHydrogeologist

with SRK Perth and

has approximately

15 years o eld

experience. His

diverse skills setcovers water

resource studies

and water allocation planning, catchment

modelling, food studies, plantation

growth, yield modelling, and mine closure

and rehabilitation. Lukes experience in

mine closure and rehabilitation includes

research in post-mining rehabilitation

and consulting projects in both South

Arica and Australia. Most recently, he

has applied the SRCE Model on Australia-

based mine closure projects.

Luke Esprey: [email protected]


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m

100

200

300

400

500

600

700

800

900

Installing grouted-in transducers

cog 3d or wrg o

rgro r c

units, and the spatial distribution o these

values. With increasing distance romthe mine, Kv values generally decrease

in importance, while Kh and storativity

values become more important.

Hydrogeologic studies commonly

piggyback exploration or

geotechnical drilling programs.

Consequently, hydrogeologists, at

least in early and middle stages o

investigation, commonly make use

o diamond-core holes, working

inside small-diameter drill rods. For

a proposed underground mine innorthern Canada, SRK designed

a program to test Kv across a

thick sequence of cemented and

recrystalised sandstones, with only

an LF-50 core rig to install wells.

Numerical pre-analysis showed that

to produce sucient pumping stress

on the aquifer to determine hydraulic

characteristics, would require a

pumping rate o 10L/s or 3 days.

The pumping well (Figure 1) included

sinking PQ drill rods to 300m, attached

to HQ drill rods to 665m depth. These

Predicting the volume and quality of

groundwater inows to a mine requires3D characterisation o the hydrogeology

in and around the mine site.

Full characterisation requires not only

transmissivity, or measurment o the

ability o rocks bordering the mine to

transmit orce and water pressure, but

separate values o horizontal (Kh) and

vertical (Kv) hydraulic conductivity o the

R O G e R h O W e l l

Roger Howellis a Principal

Hydrogeologist

in SRKs Denver

oce, and has

30 years combined

experience in mining

hydrogeology and

exploration geology.

He applies techniques o analyticalhydrogeology, economic geology, and

geochemistry, with his extensive eld

experience to the design and management

o mine-dewatering, mine-water supply,

water-disposal, and environmental-

impact studies, primarily or the mining

industry. Major projects have included

hydrogeological characterisation

beneath discontinuous permarost at

a gold property in Alaska, multi-year

investigations to design and construct

a perimeter-well dewatering system

or a diamond mine in Northern Ontario;

development o grouting and water-

handling strategies or an underground

platinum mine in Montana; and analysis

o the stratigraphy and diagenesis o

alluvial-pyroclastic basins in Nevada or

the purpose o mine-water disposal.

Roger Howell: [email protected]

Figure 1: Pumping well and monitoring or test o Kv in deep sandstone sequence

38mm screen setloosely in NQ core hole

HQ rods Kv

Kv

Grouted-in

Transducers

PQ rods

Air-injection pipe


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rods were sealed with heavy drilling

mud and cemented through the lower30m. An NQ core hole was telescoped

to a total depth o 715m, and a 38mm

wire-wrap screen was lowered through

the NQ rods to the bottom o the hole,

sticking up loosely into the HQ rods. In

a parallel core hole 18m rom the test

hole, packer testing dened a vertical

prole o Kh, and eight vibrating-wire

transducers were installed (photo above)

to monitor the pumping test.

Pumping was achieved by airliting in the

upper PQ drill rods, and averaged 9.6L/sover the 74-hour pumping period. The

PQ and HQ rods were cut and retrieved

ater the test. Pressure changes in the

transducers were analysed using a simple

MODFLOW model, and showed that

high-angle ractures in the sandstones

result in Kv values an order o magnitude

greater than Kh values. The ndings

were used or numerical estimation o

infow rates under dierent mining and

mitigation scenarios.

Roger Howell: [email protected]

hrogoog gs or oo

Mineral resources are oten

associated with complex geologicregimes that present challenges or

conceptual thought, investigatory

methods, data analysis, and numerical

modelling. Geologic terrains that

contain varied materials, mineralogic

alteration, signicant structure,

hydrothermal activity, permarost, and

subsurace gas present challenging

environments or a hydrogeologist.

In many instances, traditional

hydrogeologic eld techniques must

be adapted, methods and equipmentborrowed rom other industries, or even

equipment specically manufactured

or the task to ensure that the

required quantity and quality of data

is collected. The value o experienced

eld hydrogeologists cannot be

underestimated as they apply the skills

o the driller, engineer, plumber, general

contractor and hydrogeologist under

one hat.

Recent hydrogeologic eld programs

have yielded innovative solutions rom

many o our sta in Water Management.

Three such adaptations are described in

the ollowing bullet points.

Methodology development

and installation o groundwater

piezometers within high temperature

hydrothermal and H2S gas-bearing

aquifers, utilising low-cost plastic

materials, to depths over 500m

Design and construction of artesian

wellheads or arctic climates that allowor multiple instrumentation strings

(thermistors, pressure transducers) to

be installed down hole. Design also

allows or simple groundwater sampling

during the winter months, using a

compressed air blow back system to

remove water within the active zone

that could potentially damage the

wellhead and surace completions

Design and coordination with a

manuacturer to produce stainless

steel cement baskets or HQ core-holepiezometers with internal diameters

larger than presently available in

the marketplace. The larger internaldiameter in these cement baskets

allow for completion of higher quality

hydrogeologic tests and data collection

in exploration drill holes

Adapting standard hydrogeologic

methods or applying unusual techniques

or adapting techniques from other

industries is essential i we are to

maximise the data collection and benet

to our clients. SRK is able to draw

on the wide global experience o our

water resources personnel to meet thespecic challenges o a very wide range

o geological and mining environments

around the world. SRK can thereby

assist our clients in making the best

decisions or the operational, economic

and environmental aspects o projects.

Matt Hartmann: [email protected]

m a t t h a R t m a n n

Matt Hartmann,P.G. is a Senior

Hydrogeologist in

the SRK Denver

oce with 10 years

o experience in

hydrogeologic

characterisation,

operational

hydrogeology, and innovative drill

program management. He combines

his knowledge o hydrogeology withsignicant experience in drilling operations

and downhole completion technology

to design and implement eld programs

to investigate uncommon hydrogeologic

regimes. His experience includes

characterising high/low temp and gaseous

groundwater systems, vadose zone and

vapor phase studies, well eld assessment

and optimisation, uranium in-situ recovery

development and operations, solution

mining well design, and due diligence.

Matt Hartmann: [email protected]

Survey tape,TDX cables,and wireline

Tremie pipe


10/28

10

View o the quarry looking south

A rise in demand or cement in SouthArica led Pretoria Portland Cement

to commission an ElA in 2007 to

investigate the impacts o expanding

one of its main limestone quarries. The

quarry is located about 100km northeast

o Cape Town, South Arica. SRKs Cape

Town Groundwater Department, led by

Partner and Principal Hydrogeologist

Peter Rosewarne, was appointed

to assess the risk to downstream

groundwater users due to the deepening

of the quarry and to predict the resultant

increase in groundwater infow and the

amount and extent o drawdown.

The quarry depth of 78m as of 2007

caused a zone o drawdown in

groundwater levels in the surrounding

shale aquifer, extending ~5km to the

east but a smaller distance to the

west, because o good recharge rom

the mountainous sandstone aquifer

located there. Current groundwater

inow is ~200m3/day, with an electrical

conductivity o 260 to 310mS/m.

Using numerical modelling techniques,

SRK showed that ater 50 years o

expansion, with the quarry at 180m

depth, existing boreholes on theneighbouring arm to the east could

be expected to dry up as drawdowns

o up to 60m develop. The modelling

also showed that quarry inows could

more than double by the time the quarry

reaches ull depth development o 240m

ater 75 years, with drawdowns o up

to 100m. However, the model indicated

that only a relatively ew boreholes

would be so aected.

Some o the mitigation measures

SRK proposed included drilling newproduction boreholes to greater depths

than existing boreholes (>150m) to

tap deeper groundwater resources,

deepening existing boreholes, supplying

compensation groundwater rom the

extra inows made into the quarry and

providing compensation water rom the

plants potable water supply eed.

Peter Rosewarne: [email protected]

Groundwater fow in the vicinityo open pits and underground

mines varies 3-dimensionally

and with time. Assessing mine

dewatering commonly requires the

development o 3-dimensional (3D)

numerical groundwater models,

based on 3D geological, structural,

and hydrogeological data, to ully

characterise the groundwater fow.

SRK oten applies the nite-dierence

code Visual MODFLOW-SURFACTin

mine dewatering projects. This codegoes beyond the standard MODFLOW

code to simulate saturated/unsaturated

conditions (multiple water tables), open

pit excavation (using seepage ace

cells and collapsing model grid), and

dewatering wells using the ractured

well package. The hydrogeological team

at SRK Denver has used numerical

modelling as an integral tool or the wide

variety o mine dewatering projects

listed in the Table above. All o these

models were used to simulate passive

infow to open pits and underground

PROJECT LOCATION

Orion South/Star Saskatchewan, Canada

Olovskoye Chita region, Russia

Goldelds Nevada, USA

Paredones Amarillos Baja Caliornia, Mexico

Elegest Siberia, Russia

Elkon Yakutia, Russia

Cerro Matoso Columbia

Livengood Alaska, USA

Silangan Philippines

Hycrot Nevada, USA

McLean Saskatchewan, Canada

ip o qrr pg oo growr srs

PeteR ROSeWaRne

Peter is a corporateconsultant and

partner with 35

years o experience

in hydrogeology.

He joined SRKs

Johannesburg

oce in July 1982

and ater working

on various mining related projects in

Gauteng and Mpumulanga he relocated

to the Cape Town oce in late 1984 to

start up a groundwater section there. He

now heads a team o 12 hydrogeologists,

geochemists and technicians involved

in mining, groundwater supply, nuclear

sites characterisation, subsurace

contamination and waste disposal related

projects. Apart rom the project described

herein recent mining project locationsinclude Skorpion zinc mine in Namibia,

the Rystkuil uranium prospect in SA and

Jwaneng diamond mine in Botswana.

Peter Rosewarne: [email protected]


11/28

11

appg r growr og

or wrg projs ro wor

mines. Active dewatering options weremodelled at Elegest, Orion South/

Star, Silangan, and Hycrot; while

pore pressures or slope/roo stability

analyses were also used at Cerro

Matoso and Livengood.

Potential environmental impacts to

groundwater levels and surace water

fows were modelled at Olovskoye,

Goldelds, Paredones Amarillos, Orion

South/Star, Cerro Matoso, Livengood,

and Hycrot; with post-mining conditions,

including pit lake ormation or fooding

o the underground mine modelled at

almost all o the environmental projects.

Where active dewatering is required,

the groundwater model was used to

evaluate the most ecient dewatering

option to reduce residual passive

infow to the mine (Cerro Matoso), and

to dene the optimal pumping rates

and well spacings or the dewatering

system (Orion South/Star). Where

hydrogeological conditions are complex,

the model was used to reduce both

pumping costs and hydrogeological risksto the project (Elegest), optimising the

mine plan.

In addition to predicting dewatering

requirements and mining impacts, we

have used 3D modelling to:

Guide eld investigations to test the

most sensitive hydrogeological units

and parameters (Goldelds, Orion

South/Star, Livengood, and Hycrot)

Analyse results of comprehensive

testing programs where analytical

ormulas do not work (Olovskoye,

Elegest, Orion South, and Cerro

Matoso)

Model block cave (Silangan) and

longwall (Elegest) operations, where

hydraulic conductivity values change in

time and space above the mine area

Conduct uncertainty and sensitivity

analyses (in all o the projects in the

Table above).

Vladimir Ugorets: [email protected]

KEY COMPONENT

Two open pits penetrating very permeable deep sandstone groundwater system; comprehensive dewatering well system requiring optimisation

Underground mine intercepting a large volume o groundwater storage

Open pit excavating and pit lake inlling in environmentally sensitive area


Longwall coal underground mine under a large river

Deep underground mine within open taliks and subpermarost groundwater system

Open pit excavating in vicinity o a large river


Two deep block caves with detailed simulation o cave/crack lines propagation to the surace

Open pit excavating numerous aults connecting with deep hydrothermal groundwater system

Evaluating reeze wall and grouting options or decline and underground mine workings

vladimiR uGORetS

Vladimir Ugorets,PhD, is a Principal

Hydrogeologist in

the SRK Denver

oce, specialising in

mining hydrogeology

and groundwater

fow modelling.

He has 34 years o

experience in hydrogeology, including

17 years in Russia and has been involved

in numerous mine dewatering projects

or pre-easibility and easibility studies,mine construction, and mine operation in

US, Canada, Mexico, Russia, Kazakhstan,

Indonesia, and Philippines. He has been

involved in hydrogeological data analysis,

developing conceptual and numerical

groundwater fow and solute transport

models, predicting quantity and quality

o infow into open pits and underground

mines, estimating dewatering

requirements and designing dewatering

systems, predicting environmental

impacts o mining and dewatering

to water levels, streams, lakes, and

swamp areas, and predicting pit-lake

inlling during post-mining condition.

Vladimir Ugorets: [email protected]


12/28

12

Taking groundwater level measurements rom an exploration borehole

er sg rogoog

sssss cr Ws ar

number o which have been located in

the Congo basin and western Arica.This region is characterised by a tropical

climate with contrasting dry season/

wet season conditions, together with

poor inrastructure, communication

barriers, and widespread poverty and

security issues, which are common to

many parts o the continent. Adopting

an integrated approach in this context

provides huge benets.

In one typical example in Congo, the

early hydrological characterisation o a

remote iron ore project was maximisedthrough using existing exploration

borehole inrastructure wherever

possible, training site sta to maintain

monitoring and sampling programs, and

using portable hydrological equipment

to ease logistics and minimise

transport-related delays. The program

included:

monitoring groundwater levels from

an extensive exploration borehole

inrastructure (modied to unction as

standpipes) to provide hydrographs

and water table distribution

The requirement to conduct a mine

water assessment in the exploration toearly easibility stage usually has a dual

purpose: ocusing on initial engineering

assessments (dewatering, mine

stability, water supply, overall water

balance) and on environmental and

social aspects, typically in the orm o

an ESIA baseline study.

To meet these requirements it is often

necessary to establish a common

program o work, which involves

developing an initial conceptual

hydrogeological model (CHM),initiating a seasonal baseline water

monitoring and sampling network,

and implementing a preliminary

hydrogeological testing program.

Adopting a common work program

to meet all objectives early in

project development helps integrate

and streamline the entire water

assessment, so the ndings can be

assessed holistically. In other words, it

saves on cost and time.

SRK has successully developed this

integrated approach to mine water

assessment or many projects, a

t O n y R e x

Tony Rex isa Principal

Hydrogeologist in

SRKs UK oce,

where he manages

the Water team. A

Chartered Geologist

with a PhD in

geology and ore

deposit geochemistry, Tony has over25 years experience in groundwater,

environmental and browneld

management, combined with extensive

business and project management

expertise. Since joining SRK in early

2009, Tony has worked on a wide variety

o mine-related water management and

environmental studies in central and

West Arica, Europe, Russia, Asia and

South America.

Tony Rex: [email protected]

d a n m a c k i e

Dan Mackie is aHydrogeologist in

SRKs Vancouver

oce, with over

10 years experience,

specialising

in the physical

hydrogeology o

ractured rock and

porous media systems. In eight years

with SRK, Dan has been actively involved

in open pit and underground projects,

rom exploration to closure, bringing an

understanding o the ull mine lie cycle

into his work. His project experience,

rom the Canadian Arctic to the Andes

Mountains, has included a wide range o

groundwater eld and characterisation

methods, numerical modelling, water

management planning, engineering

trade-o studies, eects assessments and

closure planning.

Dan Mackie: [email protected]


13/28

13

Lowering a submersible pump into an exploration borehole

monitoring seasonal spring ows by

constructing simple V-notch weirs

sampling groundwater quality from

springs and selected boreholes

airlift testing rotary drill holes to provide

groundwater yield data and identiy

broad aquifer characteristics

downhole spinner testing to assess

racture permeability

At another iron ore project, this time

in Sierra Leone, a portable, generator-

powered submersible pump was

used to carry out preliminary pumpingtests in exploration holes at the pre-

easibility stage. The density o the

exploration boreholes was such that

drawdown responses in adjacent holes

were detected, providing valuable data

on groundwater characteristics and

properties, which were subsequently

used to predict early pit infow rates.

In conclusion, evaluating the

hydrogeological environment early in

an exploration or project development

program can provide invaluableinormation with signicant cost benets.


Mine water management in theCanadian Arctic involves a unique

combination o technical challenges as aunction o the geographical and geologic

setting. Characterisation and planning

or underground mine groundwater

inow management requires a thorough

understanding o northern hydrogeology,

as well as thermal effects, water quality

and logistical challenges.

The Newmont Hope Bay Project,

located in Nunavut, is planned to include

multiple underground developments, all

o which have technical challenges rom

the perspective o both groundwater

characterisation and planning:

Average annual air temperatures below

zero degrees Celsius

Permafrost (i.e., permanently frozen

ground) to depths reaching 400m below

surace and taliks (areas o unrozen

ground) below lakes

Connate groundwater with salinities

and metal concentrations oten higher

than sea water

The potential or saline groundwater

infow at many o the proposed

underground developments at Hope

Bay is a concern. Developments

occurring within lake taliks, oten

within 100 to 200m vertically o the

lake bottom, or below permarost will

not have the benet o rozen ground

to limit infow. Regionally, some mines

have experienced relatively high infows

o saline groundwater.

In 2010, an on-going groundwater quality

sampling program was initiated within

taliks and below permarost. To developa valid baseline, permanent installations

were required capable of year-round

operation through rozen ground. To

provide this capability, SRK designed

Westbay multi-level monitoring system

installations, providing the ability to

physically separate the unrozen sample

zone targets rom the access pipe, which

can pass through 400m o rozen ground.

Using sampling tools passing through

anti-reeze-protected access pipe,

water samples and pressure data arecollected rom the target zones, allowing

or development o vertical proles o

both water quality and pressure, after

correction or density.

Results rom repeat sampling have

indicated that, at a minimum, infow

salinity will be typical o sea water

concentrations. As part o QA/QC

procedures, stable isotopes (oxygen &

hydrogen) are collected to provide an

additional comparison with drilling waters,

to ensure that sucient purging hasoccurred. Isotope data indicate water

quality types different than drilling water,

validating the sampling results.

The data collected has allowed SRK to

better constrain predictions o potential

inow water quality, and provide valuable

input to the development o site water

management plans.

Dan Mackie: [email protected]

ifow wr q - hop B,n

SHALLOW LAKE

CONTINUOUS

PERMAFROST

>500m

MONITORING WELLS

MINE INDUCED

GROUNDWATER

FLOW

TALIK

(CONNECTED)

PIEZIOMETRIC SURFACE

(OPERATIONAL)

UNFROZEN ROCK

} MONITORING ZONE

PACKER

REGIONAL GROUNDWATER FLOW-

CONTROLLED BY LAKE ELEVATIONS

DEEP LAKETALIK

(ISOLATED)


14/28

14

Beadell Resources Limited appointedSRK to prepare a easibility study o the

Tucano project located in the north oBrazil, in Amap State, where the mean

annual precipitation is approximately

2.4 metres.

The easibility study included surace

water management or the pits (Tapereb

AB, Tapereb C, Tapereb D and Urucum)

and the associated waste dumps. The

main ocus was to divert clean runo

upstream o the acilities and collect

potentially impacted water downstream.

SRK identied three elements thatrequired special consideration in this

project:

With the type of soils on site and

constant rainall year-round, nding

the ideal scenario to manage

sediment problems

Locating surface water infrastructure

with limited space and the existing

and proposed mining acilities on site

Given the proximity of the facilities

to William Creek, identiying theminimum do-not-disturb area near

the creek

SRK analysed the minimum particle size

to be held in each o the retention ponds,

using the results o site monitoring and

geotechnical laboratory tests. Based

on the results o the calculations, the

expected values o total suspended solids(TSS), in most cases, were lower than the

maximum TSS threshold; however, only

approximately hal o the turbidity values

complied with the requirements, so

adding focculants was recommended.

The size o the surace water

inrastructure was reduced by ocusing

on minimising the infow o water

rom outside o the mine ootprint

boundaries, to deal with the limited space

available. Additionally, including various

lining materials, such as high-density

polyethylene and riprap, minimised the

design sections to optimise the land use.

Location o the sedimentation ponds

was a high priority to reduce the projects

impact on William Creek. Criteria included

use o minimum catchment areas and

minimum disturbance to the natural

environment. The contacted water was

collected in sedimentation ponds to allow

solids to settle and, i needed, to add

chemicals and focculants. Claried water

rom the sedimentation ponds will be

discharged into the natural creek system

that fows into William Creek.

Juanita Martn: [email protected]

Sedimentation pond at Tucano project

Sr wr g jg o Br

SRK has had extensive experience

working on mine water supply projectsin Middle Eastern countries, particularly

in Saudi Arabia. The climate in this part

o the world is mostly arid with very

limited rainall, runo and recharge.

It ollows that one o the major

challenges mines ace is guaranteeing

a sustainable long-term supply o water

or the mine operation.

While there are some very extensive

sandstone and limestone aquifers in

the Middle East, which are particularly

evident in the northern and easternsides o Saudi Arabia, these sources

have become severely depleted over

recent decades as demand has vastly

outstripped natural replenishment by

recharge. With the exception o the

phosphate and bauxite operations

in the north o Saudi Arabia, most

mining projects in the Kingdom are

in the Arabian Shield on the western

side o the country, at a considerable

distance rom any o the higher

yielding sedimentary aquifers. Formost mines located in the Shield, local

Constant rate pumping test in the Arabian Shield


15/28

15

m wr spp m es

wadi sediments and ractures in the

crystalline bedrock provide the onlysources o water; however, these

scarce resources are also used by the

Bedouin and local settlements and,

thereore, are highly sensitive. Clearly,

water or potable use by the local

population invariably takes precedence

over any planned industrial use.

Finding solutions to the scarcity o

surace and groundwater resources

and to strategic issues, such as local

competition or the same resource,

often requires an unconventionalapproach and considerable lateral

thought. SRK has ound that in this

environment, it is especially important

or the operator to tailor the mine

production and processing to match

the available resource and actor in

any expansion programs at a very

early stage to ensure that uture

water sources are reserved beore

being taken or other developments.

Where the project requires more

water than is available locally, thencareul consideration must be given

to improving management practices,

to minimising wastage through pastetechnology, recycling water in the mine

circuit, using advanced technologies

like reverse osmosis, or the use o

alternative supplies. For example,

alternatives include piping water rom

more distant catchments, the sea, or

by using grey water rom nearby urban

centres. Some o these solutions are

expensive, so have to be considered

within the ramework o an overall cost-

risk-benet assessment. In some cases,

it may be necessary to set up alliances

with other mines, industries or local

government to introduce economies o

scale where water use would otherwise

be prohibitively expensive.

SRK advises mining companies to

consider assessing potential water

resources at a very early stage, using all

possible options to ensure that potential

mine development is optimised to

those available resources and not based

on unrealistic expectations.


William Harding: [email protected]

W i l l i a m h a R d i n G

William Hardingis a Principal

Hydrogeologist

with SRK in the

UK. His 20 years

o experience in

hydrogeology related

to mining includes

Hydrogeological

Impact Assessments supporting license

applications or quarry extensions, well

testing to characterise mine hydrology,

numerical modelling to assess tailingsseepage, and to design well elds or

water supply and pit slope stability. His

projects cover easibility studies on pit

dewatering or slope stabilisation, water

supply, and mine water management.

He has completed quantitative risk

assessments o tailings waste acilities

and perormed due diligence or mergers

and acquisitions.


J u a n i t a m a R t n

Juanita MartinP.Eng (Civil) is a

Principal Consultant

in SRKs Perth

oce with more

than 20 years o

experience in the

coordination, design

and supervision o

civil engineering projects and in water

management or mining inrastructure.

Her experience includes the design o

hydraulic structures or impacted and

un-impacted runo rom tailings and

waste rock dumps, retention pond and

spillway design, the preparation o pond

and tailings water balances, and tailings

water management. Juanita has a broad

base o experience rom her work in

climates ranging rom the arid areas in

northern Chile and Western Australia to

the tropical areas in Venezuela and India.

Juanita Martin: [email protected]


16/28

16

V-notch weir to monitor rock pile discharge Underground sump with fow meter

Wr o b or

rgro nw mo

workings. Detailed infow mapping

and chemistry o the various infowsenabled distinct sources o infow to

be identied.

The dewatering system was inventoried

and instrumented at 14 locations with

non-intrusive ultrasonic fow meters.

Pumps were cycled using level switches

to eliminate fow measurement

intererence rom air bubbles entrained

in the pipe fow by the pumps pulling

air. Bag dams with v-notch weir plates

collected and monitored infows, and

fumes were deployed in ditches withsignicant fows. The devices were

tted with data loggers or automated

recording o data.

Field data logging instruments

were adapted to the active mining

operations where routine access

to various monitoring locations is

restricted. The unattended eld

instruments needed to be reliable in

the presence o dust, high humidity

and electrical power fuctuations.

Developing a water balance or an

underground mining operation canrequire a variety of measurement

techniques to deal with the following

challenges:

Operational efciency may result in

mixing water sources that must be

characterised separately to develop a

detailed water balance

Combining all waters in mine

discharge may mask variations in

fow and chemistry

Operational activities can makecomponents o the fow system

inaccessible

Infow rom surace sources aects

the otherwise relatively dry Questa

Molybdenum Mine located in

northern New Mexico. Mining by the

block cave method has produced

a subsidence zone that captures

surace water drainage. Data collected

or a comprehensive water and

chemical load balance demonstrated

containment by the underground

laRRy cOPe

Larry Cope oSRKs Ft Collins

oce, is a Senior

Hydrogeologist with

a Master o Science

degree, has 25

years experience

consulting to the

mining industry.He specialises in

aquier hydraulic testing and analysis,

hydrogeologic characterisation, mine

water management, and environmental

data management. Recently, Larry led

the hydrogeologic investigations and

mine water management at the Questa

Mine in New Mexico, and currently hes

investigating potential modications to

the mine water management system at

the closed Homestake Mine, as that mine

is converted to the Deep Underground

Science and Experiment Laboratory

(DUSEL) by the NSF and DOE.

Larry Cope: [email protected]

BReeSe BuRnley

Breese Burnleyo SRKs Reno

oce has 18 years

o experience in

mine and municipalwaste disposal

site engineering,

permitting, and

closure. He

specialises in planning design and

implementation o water management

acilities or closure o heap leach pads,

tailings impoundments, waste rock

dumps and landlls.

Breese Burnley: [email protected]


17/28

17

Caustic supply tank and in-line pH adjustment system Tonkin Springs Mine, Nevada

Continuous monitoring o mine ditch fow

The data demonstrated that infows

balanced to within three percent othe measured mine discharge volume,

indicating that virtually all infow water

was captured and contained in the

workings. The chemical load balance,

developed from quarterly samples at

each fow monitoring station, enabled

the sources o infow to be identied.

Conclusions drawn rom the

investigation showed that 1) a high

density of ow data and quarterly

samples is required to address seasonal

changes in infow rates and chemistry;2) creative solutions to adapt existing

underground water management

acilities can eectively monitor fows

in detail yet minimise intererence

with operations; 3) ultrasonic metering

o mine water pipe fow is viable and

eliminates intrusive installations; and,

4) relatively simple data sets can provide

critical insights to sources o infow

waters and chemical changes to them.

Larry Cope: [email protected]

This article describes 1) methods olocating abandoned boreholes within

a side hill pit, and 2) the design and

operation o in-line pH adjustmentacilities or low-pH pit water.

Historic exploration boreholes in the

base o Pit 1 at the Tonkin Springs Mine

in central Nevada intercepted conned

groundwater at depth. These boreholes

were originally abandoned without

sealing, which resulted in artesian

groundwater fow into the pit base,

contact with in-pit sulde rock, and

ormation o a perennial pit lake in the

pit base containing low-pH mine drainage.

SRK Reno developed a plan or locating

and sealing known boreholes, including

the construction o a system directing

fows to the tailings impoundment to

render the pit base ree-draining.

During drying out o the pit base, SRK

used survey coordinates and tracked

permanent wet spots to locate open

boreholes. The mine continued the

process, closing more than 100 open

boreholes over a three-year period,

and reducing post-closure water

management fow by up to 15gpm.

The pit sump is gravity drained via a pre-

constructed HDPE pipeline that exits the

low point o the pit and fows through

an in-line pH-adjustment system and

then to the tailings impoundment. The

pipeline is buried below ground surace

or protection against reezing and is laid

within a secondary containment pipeline.

The in-line pH-adjustment system sits in

a buried precast concrete vault. High-

frequency measurements from ow andpH meters continuously adjust dosing

pump speed and stroke length, adding

caustic or a range o incoming seepage

fow rates (0 to 52gpm). Caustic is

injected into the pipe fow upstreamrom the meters, and water then fows

through an in-line static mixer beore

reaching the fow and pH meters or

continuous pH adjustment. A data logger

is used to record and transer pH and

fow data to a laptop computer.

The pH adjustment system includes

a sump-pump to keep the vault dry,

a strobe to alert mine sta o power

outages, a wall heater to prevent

reezing/condensation, air vents with

motion-activated ans to circulateresh air, and sensors to detect pump

diaphragm or caustic eed problems

and automatic shut-o fow valves.

Dave Bentel: [email protected]

Breese Burnley: [email protected]

Wr g or osr, n

dave Ben tel

Dave Bentel hasover 30 years

o experience

providing

engineering and

environmental

permitting services,

and nancial

estimating services

or mining acilities. He specialises

in cost-benet evaluations, using

risk-based assessments o water and

waste management acilities, and

planning, design and implementationor closure and reclamation o mine

inrastructure, processing plants, tailings

impoundments, heap leach acilities,

open pits and waste rock acilities.

Dave Bentel: [email protected]


18/28

18

In hard rock mining environments,

groundwater fow along racturesdominates. In order to understand the

nature o ractures, and particularly

those that are continuous and inter-

connected within a wider racture

network, SRK employs specialist

eld investigation techniques. The

opportunity to design and undertake

such investigations within an

integrated program o geotechnical and

hydrogeological investigation can yield

enhanced results. The collaboration

enables a more comprehensive

assessment o the groundwater

regime around mines and specically

or open pits, pit slope stability.

For an open pit easibility study in

northern Sweden, SRK designed

such an integrated study with the

objective o understanding variations

in horizontal hydraulic conductivity (Kz)

with depth in the planned pit wall areas.

Diamond-cored boreholes enabled

the geological sequence in this case

ractured granitoids, diorites, phyllites,schists and skarns to be accurately

Downhole fow logging

A FIFA requirement or South Arica tohost the 2010 Soccer World Cup was

that host cities assure adequate and safe

water supply or the event and visitors.

This requirement was in line with that of

many municipalities in the United States

to develop a Source Water Protection

Plan (SWPP) or protecting and managingthe supply o water to users and

consumers, and is an initiative SRK has

been working on with various industrial

and mining clients.

The program has relevance or

mining operations in understanding

the vulnerability and sustainability o

the water sources available to the

mine, and the mines impact on water

source sustainability, while eectively

collecting and managing inormation on

their interactions within the water cycle.

A central component o the SWPP

program is the Source Vulnerability

Assessment (SVA), which is the

process o assessing the vulnerability o

the current water resources available to

the mine on the basis of assured quality

and quantity, in understanding the

demands and threats to the available

water sources, and identiying and

determining alternative water sources

that may be available to alleviate any

threats to the primary resources,

considering both groundwater and

surace water as potential resources.

SRK has extended the SVA to consider

the perormance o on-site raw water

treatment, storage and distribution

acilities, and wastewater management

and treatment acilities relative to

corporate, international and national

perormance specications.

Moving on rom the SVA, a SWPP is

developed, setting out a site specicwater management vision, objectives

and goals, action plans to meet

identied vulnerabilities, resource

requirements, time lines and budgets,

monitoring, communications with

authorities and associated interested

and aected parties, internal and

external perormance audits, and

continuous review and updating.

Andrew Wood: [email protected]

Sor wr proo pg

a n d R e W W O O d

Dr Andrew Woodobtained a PhD in

Pollution Control

rom Manchester

University in 1983.

Ater 5 years at the

Council or Scientic

and Industrial

Research in Pretoria,

he joined the Water and Environmental

Technology (WET) group o SRK SA

in 1989. Since that time, Andrew has

specialised in minewater, waste and

efuent management; waste minimisation

and resource management, water and

sewage treatment plant process design,

the remediation o contaminated sites

and risk management.

Andrew Wood: [email protected]

S a R a h l y l e

Sarah Lyle isa Consultant

Hydrogeologist

with SRK in the UK.

Ater receiving her

masters degree in

hydrogeology, she

worked in SouthAmerica or two years,

where projects included hydrogeological

mapping, numerical modelling and

contaminant management or a large

operating mine in Peru. Since joining SRK

in October 2010, Sarah has worked on

water management and characterisation

studies in Central and West Arica, and

mine-related environmental and easibility

studies in northern Europe.

Sarah Lyle: [email protected]


19/28

19

igr go-rogoog

sgos Sw

logged. The oriented core was logged

geotechnically, or properties includingRock Quality Designation (RQD) and

fracture frequency (FF).

The drillers were instructed to notiy

SRKs supervising hydrogeologist o

any signicant increase in penetration

rate and any loss o drilling fuids during

drilling. Such events indicate potential

racturing in the rock. In the example

shown, evidence o racturing occurred

between 258m and 262m below ground

level. A downhole acoustic televiewer

(ATV) survey provided urther detailo racture characteristics, including

racture aperture at the borehole ace.

When the drilling was completed, SRK

used a downhole impeller fow-logging

technique, known as spinner testing,

to accurately assess the variation

o hydraulic conductivity with depth

through the sequence. The testing takes

place under pumped conditions, using a

portable submersible pump to quantify

the induced fow (Qspin in L/min) rom

ractures down the hole.

In this case, more than 70% o the total

fow was derived rom a depth o 258m,corresponding to the main racture

zone. This, and other, fow horizons

identied during the logging were then

converted to a discrete measure o

the ractures permeability, using the

total transmissivity (T) o the rock mass

penetrated by the borehole.

Acoustic Televiewer Log

The integrated study enabled SRK to

evaluate the racture characteristics o therock mass accurately. Further, this approach

led to the clear identication o an open

racture zone as the conduit or the majority

of groundwater ow in the sequence. The

application of these techniques enabled an

improved understanding o the conceptual

hydrogeological model and a more accurate

prediction o pit infows.


Sarah Lyle: [email protected]

Core log with spinner test results


20/28

20

Drilling o hydrogeological boreholes and installation o pressure transducers

i-p wr oro

Grb Rss

Given the environmental sensitivity

o the nearby salmonid-bearing rivers,the project aced two signicant water

treatment and disposal challenges: the

high incidence o suspended sediments

in pit seepages with very poor settlement

properties, and the elevated salinity o

groundwater drawn rom the deeper

ormations by the dewatering system.

SRK addressed the issue o suspended

solids in water by using Silt-buster

technology.

To solve the potential salinity problemduring the nal phases o mine lie, SRK

proposed two principal options:

Option 1. I only a small volume o

brackish water is encountered in

deeper ormations, then the efuent

rom dewatering could either be

disposed o directly to a nearby karst

lake, or back in to the abstracted

aquifer at a suitable distance from the

dewatering operation.

SRK works with clients to develop

eective strategies or managing suraceand groundwater in open pit mines.

SRK recently completed a bankable

level easibility study or the Grib

Diamond Mine in Northern Russia

where many o the issues associated

with controlling water in the open pit

environment can occur.

The results o SRKs site investigation

and numerical modelling o mine

dewatering indicated that more than

one depressurisation method wouldbe required to optimise the pit slopes.

The nal design included a ring o

vertical dewatering wells around the

circumerence o the pit to dewater the

more permeable shallow ormations,

and several layers o sub-horizontal

drain holes in the lower hal o the pit to

depressurise the less permeable strata.

This design resulted in steeper, more

stable slopes.

hOucyne el idRySy

Dr HoucyneEl Idrysy, PhD

Hydrogeology,

participates in

high-level easibility

studies and

projects related

to groundwater

resources evaluation

and management. He is particularly

skilled in modelling groundwater fow

and contaminant migration, combining

geostatistics, geology, GIS and numerical

methods. His mining project experience

includes the design and supervision

o hydrogeological site investigations,

optimisation o dewatering systems,mine water supply and management,

pollution remediation and control. He

has carried out projects that address

landll and contaminated land, assessing

environmental impacts and risks

o groundwater and surace water

contamination related to mining, industrial

development, agriculture, and waste

disposal.

Houcyne El Idrysy: [email protected]


21/28

21

Combined waste rock and tailings disposal acility at Martha Mine, Waihi, New Zealand. SRK sta evaluated the

perormance o the multilayer cover over the embankment constructed o sulde bearing waste rock.

Option 2. I the volume o brackish

water is large, then it should be treatedusing reverse osmosis (RO) and the

waste brine pumped to the karst lake.

There is a high cost associated with

the installation and operation o an RO

plant, so SRK introduced appropriate

modications to the dewatering design

or Option 2 to delay its introduction.

This or example included the use o

bridge plugs to temporarily close o the

lower sections o each dewatering well

until such time that dewatering o the

deeper formations was required.

In SRKs experience, the development

o an eective water management

strategy or open pit mines depends

critically on close collaboration

between the water, geotechnical and

mining teams.

Houcyne El Idrysy: [email protected]


Sulde bearing rocks in waste dumps,spent copper heap leach piles, ore

stock piles, pit walls, coal spoil and

dewatered tailings storage acilitiescan be long-term sources o water

contamination. Suldes, when exposed

to oxygen and water, oxidise to produce

sulates and acid.

Under acid conditions a wide range

o metals are more soluble. The

resulting leachate is known by several

terms, including acid and metallierous

drainage, acid rock drainage and acid

mine drainage. Sometimes, interactions

with rock neutralise acid. The resulting

solution, though pH neutral, may containhigh concentrations o dissolved solutes,

e.g., sulate and some metals.

In many instances, acid and

metallierous drainage have high level

negative impacts on the environment

and require high cost and long-term

remediation and treatment measures.

SRK has extensive global experience

in assessing the quantication of

sulate production rates, the prediction

o leachate geochemistry, and theeects on receiving waters. We have

also designed strategies to control the

development o sulde oxidation and

have established methods to measure

the eectiveness o the control

strategies or clients.

a ros rg

andReW GaRvie

Andrew Garvie, PhDPhysics, is a Principal

Geoenvironmental

Consultant in SRKs

Sydney oce. He has

20 years experience

in assessing the

potential o suldic

mine wastes to oxidise

and produce acidic and metallierous

mine drainage (AMD). Andrew has

designed, managed and conductedsite and laboratory investigations o the

physical processes and geochemistry

leading to AMD. Other project work has

involved quantiying the eectiveness

o AMD management strategies. His

experience is international, including

Australia, Indonesia, New Zealand, USA,

Canada, China and Kazakhstan.

Andrew Garvie: [email protected]

Identiying the presence o suldes in

various waste rock types and ore across

the deposit, on a sound statistical basis

during exploration, and incorporatingthe management o suldes into the

early overall mine plan provides the

best opportunity to meet regulatory

and local community expectations,

while maintaining control over water

management costs.

Andrew Garvie: [email protected]


22/28

22

Wr-r ro ss or o proj c Pgo

SRK Chile has recently participated

in dening the water base line requiredby the EIA to obtain an environmental

permit or the Riesco Island coal

project, and in other water-related

works. Riesco Island is located 60

kilometers northwest o Punta Arenas

in Region XII o Magallanes. The project

involves a pit with an in-pit waste dump,

external waste dumps, a stockpile at

the port and supporting inrastructure.

West o this project, the same company

has started easibility studies on

another coal deposit. Because the local

community has been very sensitive to

the potential environmental impacts on

Riesco Island, the studies have been

carried out to a high technical standard.

The area has continuous rainall, with

average monthly values o 30mm andmean annual precipitation o 447mm/year.

Studying the storm water management,

conservation of the river water quality and

protection o the peat and the watershed

zones posed a great challenge.

Land orms in the project area are

heavily infuenced by the erosive

action o old glaciers, generating

deposits o moraine-type glaciofuvial

materials, glaciolacustrine, drumlins,

etc. The underlying bedrock comprises

a folded sequence of Tertiary marineand sedimentary deposits that include

sandstone intermixed with mudstones

and siltstones (Loreto Formation). The

several coal layers o economic interest

are ound in this ormation.

The hydrogeological setting is

dominated by two areas. The upper

glaciouvial layer is mostly an aquitard

composed o heterogeneous material

o predominantly low permeability. The

lower layer is the Loreto Formation

where the groundwater fows throughzones associated with open joint

systems or layers o high porosity within

the sedimentary rocks.

SRK used its experience in eldwork,

including geophysical prospecting,

piezometers drilling and installation,

Lugeon testing and water quality

sampling to understand hydrogeological

systems and assess environmental

impacts rom uture mining activities.

Chemical and geophysical studies

provided key inormation to interpret

the hydrogeologic dynamics, as did

the impact assessment study on the

surrounding small lagoons and peat

lakes. High tritium content, indicating

younger waters in rock ormation than in

the glaciofuvial cover, helped to explain

the recharge mechanism and provided

valuable inormation or use in the uture

modelling o the pit dewatering.

Beatriz Labarca: [email protected]

Large mining projects, currently

being developed in Chiles northernregion, are generally located in the

Andes Mountains at altitudes o 3000+

meters above sea level. Possible

sources o water supply or mining

are the mountain aquifers and sea

water. Due to Chiles geographic

conguration, using sea water is

always easible, as the average width

o the country in the northern zone is

150km to 350km. However, the great

altitude or pumping increases the

capital and operating costs.

Searching or water in the Andean

aquifers is an alternative that poses

a great hydrogeological challenge as

these aquifers form part of complex

geological systems. In a modern

volcanic environment, periods o

sediment deposition alternate between

volcanic fows o dierent origins

and poorly consolidated material o

BeatRiz laBaRca

Beatriz Labarca,Principal Geologist

rom the Universidad

de Chile, specialisesin hydrogeology. She

has over 12 years o

experience in mine

drainage issues

and prospecting

groundwater supply, and is an expert

in simulating models o groundwater

fow. Beatriz has a solid understanding

o drainage aspects o ractures in

underground and open pit mines

and pressure pores in rock mass, in

hydrological data management and

basin balances. She has experience with

design and construction supervision

o pumping wells and observation

piezometers, hydrochemistry, geophysical

methods applied to hydrogeology,

hydraulic testing, and legal consulting

concerning water rights.

Beatriz Labarca: [email protected]


23/28

23

Wr spp: rsg g

c g

Exploration well (let) ; 14 day pumping test, Chilean Andean Plateau, Region III (above)

varying grain size, and is structurally

superimposed by a complex aultsystem which causes very deep and

complex hydrogeological basins.

Low rainall in this high-altitude

desert environment and the lack o

meteorological stations to provide data

on rainall, snowall and evaporation,

make it dicult to predict recharge

to the aquifer systems. On the other

hand, some unique biotic ecosystems

and water sensitive systems in

the Andean valleys limit the ability

to exploit these aquifers from an

environmental point o view.

SRK has evaluated an aquifer located in

Region III o the Andes Mountains at a

median altitude o 4300 meters above

sea level, which could ensure the

water supply or a large mining project.

The project, located approximately

125km from the well eld, requires an

average fow o 785L/s or 68 thousand

m3 o water per day.

The hydrographic basin, where a

complex aquifer system has beenidentied, covers approximately

520km2. Inormation was obtained

rom 16 pumping wells and 26

exploration and monitoring wells, as

well as rom the results o several

geophysical, chemical and isotopic

works.

The evaluation allowed SRK to dene

an aquifer system with excellent

hydrogeological characteristics to

support wells whose perormance

will surpass 100L/s. To veriy thatexploiting this aquifer will not cause

adverse eects on environmentally

sensitive areas, SRK built a numerical

model of the aquifer operation, which

demonstrated the easibility o using

the well eld to supply the needs o

the mining project with no measurable

eects downstream.

Osamu Suzuki: [email protected]

O S a m u S u z u k i

Osamu Suzuki,Principal

Hydrogeologist

with SRK Chile, is a

Hydraulic Engineer

with more than 38

years o experience

in hydrogeology. In

his 20 years as a

consultant, he has led various projects

or mining companies in groundwater

resource evaluation and supply, as well

as in technical aspects o water rights

permitting and environmental studies

related to water resources. Osamu has

extensive knowledge o geophysical

interpretation, water geochemistry,isotopic hydrology, and aquier modelling,

with in-depth training in laboratory and

interpretation techniques o isotopic

data at Waterloo University in Canada.

He has served as a UNDP expert in

hydrogeological projects in northern Peru

and Costa Rica.

Osamu Suzuki: [email protected]


24/28

24

Remote tropical mining location

m wr g

w GoS ios

water, dust suppression and vehicle

washing. All supplies must beidentied and characterised or yield,

reliability, seasonality and location.

Balancing demand to supply yields

over time becomes central or design

specication, permit application,

inrastructure scheduling, risk

assessment and cost optimisation.

Modelling is used to evaluate risk

and to identiy and test strategies

to secure a sae supply, integrating

and optimising all o the mine water

system ow, storage and qualityprocesses. The resulting strategies

determine infrastructural requirements,

costing and scheduling.

Once the strategy is developed and

documented, it can inorm planning

over the project lie. With water usage

increasingly constrained by social,

environmental and statutory actors,

the mine water management plan

becomes important or operators and

regulators alike, or all aspects o water

usage, storage and discharge.

SRK is carrying out a major water

management study or a condentialclient that is currently developing

several coal contracts extending 150 km

in Kalimantan, Indonesia. Our services

cover water monitoring, supply,

drainage, storage, diversion, discharge

and closure planning over the lie o the

project and address design, costing and

scheduling o all water and sediment

management inrastructure. Given the

complexity and scale o the project

along with an average annual rainall o

4500mm, key challenges lie ahead.

A undamental component o any

mine water management plan is

achieving a representative water

balance. This is especially dicult

early in project development, as it

relies on design specication data or

orecasting water demand, and on

environmental data or planning water

supply, where inormation is oten

incomplete or inaccu

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