Welcome and agenda Description Time 1 Welcome 7.00 pm 2 - - PowerPoint PPT Presentation

TERRAMIN AUSTRALIA LIMITED

Bird in Hand Gold Project Woodside Community Consultative Committee

Water Technical Reference Group Meeting Wednesday 26th July 2017 Woodside Bowling Club

Welcome and agenda

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Description Time 1 Welcome 7.00 pm 2 Orientation: how we came to be here

• Community engagement opportunities
• Progressing the WCCC
• 7. 05 pm

3 Review of water studies 7.20 pm 4 Thank you, next meeting and close 9.00pm

Community consultation

In the past, Terramin has conducted:

• public meetings
• one on one meetings and small group meetings
• drop in session

This community input has been used in Terramin’s work to date in putting together its mining proposal

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Opportunities for the local community to be involved

• The WCCC has been established to promote a community based approach

to broad community engagement rather than a Terramin led process

• special focus groups will be held by Terramin to directly address particular

community groups and respect unique circumstances such as ‘some members of the community have more to lose / gain than others and this must be recognised and taken into account’ (comment made at the first WCCC meeting 3rd July 2017)

• drop in sessions may be held that could include presentations from the

mining regulator and other stakeholders

• community members will always have the right to contact Terramin or the

mining regulator directly as well as other stakeholders like their local elected members or relevant Ministers of government.

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Moving forward

Handover

• Christine Charles is MD of a company called Design for Growth and is working with

Terramin

• Christine along with Katy and Matt who you know, will be the ‘go to’ people within

Terramin

WCCC governance working party

• Terms of Reference
• Independent Chair and secretariat

WCCC meeting

• Complete introduction to WCCC core group members
• Special item CSIRO survey
• Reports from WCCC governance working party
• Key issue (s) for consideration

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WCCC Water Technical Reference Group (TRG)

• Learn more about the ground water assessment report for

the Bird in Hand Gold Project, and the independent review

• Understand the purpose of the report
• Ask questions
• Provide comments and other input
• Identify challenges, concerns and priorities
• Identify opportunities

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Water issues brought forward from last WCCC meeting

• A closer look at the data collected
• An understanding of the assumptions used in the Assessment

Report

• An understanding of the modelling with a special focus on its

reliability

• An understanding of the potential for salinity migration in the

catchment

• An understanding of the likely volume of any water that may be

released into the mine, plans for any reinjection for any of this water and methods of any proposed reinjection

• An understanding of water allocation requirements, water planning

and / or water purchase that may be required

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TERRAMIN AUSTRALIA LIMITED

SLIDE No. 8

Groundwater Technical Reference Group Tonight’s format

 Groundwater

• Existing conditions and Modelling

– Jason van den Akker Hydrogeologist  Underground water management strategies

• Grouting: what and how?

– Katy Fechner Terramin

• Depressurisation and Reinjection

– Matt Daniel Terramin

• Groundwater Monitoring Networks

– Matt Daniel Terramin  Question and Answer Session

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 9

Approach

 Information gathering (>3 years)  Develop conceptual groundwater model  Build computer model  History matching  Groundwater predictions  Independent review of conceptual & computer models

Conceptual model Computer model

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 10

Information gathering

 Anecdotal evidence (1930’s & 50’s)  Groundwater levels (regional flow pattern)  Groundwater pumping  Groundwater recharge (rainfall)  Groundwater & surface water interactions  Drilling & aquifer testing to understand aquifer permeability

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 11

Conceptual groundwater model – Regional scale

Groundwater flow direction Project site

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 12

Conceptual groundwater model – Local scale

Fractures Marble Historic BiH mine Proposed mine decline NW SE

 Aquifer characterised based

• n
• >60 exploration holes
• 5 investigation bores
• Several aquifer tests

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 13

Computer model

 Groundwater models are computer models of groundwater flow systems.  The model was developed to:

• Represent the current state of groundwater
• Predict the rate of groundwater inflows
• Assess groundwater impacts
• Evaluate water management options

Project site

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 14

Computer model construction

 900,000 model cells (5 to 50 m3 in size)  Assign aquifer (rock thickness, dip, faults)  Assign aquifer properties such as permeability  Regional groundwater flow into & out of model (catchments)  Add private bores (pumping)  Add rainfall recharge  Add Inverbrackie Creek

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 15

History matching

 Model Calibration – matching historic observations to model predictions  The model needs to replicate:

• Current groundwater flow pattern – 35 observation bores
• Seasonal groundwater level change due to pumping – 28
• bservation bores
• The results of the 6 day pumping test – 20 observation

bores

• Historic mine dewatering – Mine managers records &

Government reports used to validate model

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 16

History matching to observations at 28 bores

Project site

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 17

History Match – Simulation of regional groundwater flow pattern

Project site

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 18

Model review process

 Groundwater modelling guidelines  120 compliance criteria  Iterative process looking at

• Planning
• Conceptual model
• Design and construction
• Calibration & sensitivity analysis
• Predictions of impacts

 Model is fit for purpose  Government will conduct its own review

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 19

Model uncertainty

 Robustness of the model is based on the amount of information available to inform construction

• Limited info = low confidence (need to make assumptions)
• More info = higher confidence (less assumptions)
• This model has evolved over 3 years

 Sensitivity analysis:

• What parameters is the model sensitive to?
• How does altering these parameters influence the model

predictions of impacts?

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 20

Uncertainty

 Worst case  Interception of water bearing fault (beyond 60 L/s)  Different grouting effectiveness (reduce inflows to 4 to 12 L/s)  Increase aquifer permeability (+7 L/s)  Reduce rainfall recharge

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 21

• Located in Western Mt Lofty Ranges Prescribed

Water Resource Area - September 2013. Unlimited GW use prior to then. Now 940ML/year.

• The rules of the WAP are designed to protect the

groundwater system and the rights of existing users to a sustainable groundwater supply.

• Terramin will protect the groundwater and existing

users through the same rules.

• Terramin have not started exploring options with the

department to clarify water licensing on inflows and reinjection

• WAP binds Terramin to same “no impact” rules

Water Allocation

Water Allocation Plan

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 22

Water Allocation Plan Principles

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 23

Law - Proposed Outcome Criteria What we are proposing to be monitored against  All aspects of the project have outcome statements like these  Provide the basis for all design and monitoring  WATER “No adverse impact to the supply or quality of water by the mining operations to existing users and water dependant ecosystems”

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 24

• 1. UNDERSTAND – existing

geology and hydrogeology

• 2. DESIGN – mine plan to

avoid water bearing zones

• 3. PROBE – ground

conditions ahead of mining to know what’s ahead

• 4. GROUT – Grouting for

groundwater control

• 5. REPLACE – reinject

groundwater back into the aquifer around the mine

Groundwater Management Strategy

How can we manage groundwater impacts?

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 25

• 1. UNDERSTAND and 2. DESIGN to avoid

fracture zones

Fractures in the “Hanging wall” Marble Historic BiH mine Proposed mine decline NW SW

 >60 drillholes

• Fracture

mapping

• Targeted

investigation bores

• Several

aquifer tests

• Creates a 3D

model of geology

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 26

 Pre-excavation grouting is used to stop or reduce groundwater inflow into the mine  Cement is pumped into the fractures approximately 2-5m around the mine void prior to progressing the tunnel  The need to grout is determined by the results of the probe drilling and conditions encountered during mining process  Constantly builds on info from steps 1 and 2

• 3. PROBE and 4. GROUT process

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 27

 Why?  Identify old mine shafts, geology check, rock strength for tunnel, water bearing fractures ahead of tunneling

• 3. PROBE drilling and 4. GROUT process

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 28

 Why?  Identify old mine shafts, geology check, rock strength for tunnel, water bearing fractures ahead of tunneling

• 3. PROBE drilling and 4. GROUT process

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 29

 Why?  Identify old mine shafts, geology check, rock strength for tunnel, water bearing fractures ahead of tunneling

• 3. PROBE drilling and 4. GROUT process

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 30

 Probe hole diameter

• 40-63mm

 Are inflows larger than predicted?  Do we need more probe holes to explore or inject grout?  Is the grout working? Checking from verification probe holes

• 3. PROBE and 4. GROUT process

Continuous checking

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 31

Water Pressure Entering Through Probe Hole and Engineering Formulas for Grouting

 Pressure gauges allow us to understand the hydrogeology and the fracture ahead  Grouting program designed in response to the probe drilling program at each face  Inflows determines how much grout applied - equation  Holes drilled after grouting to check grout is effective

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 32

Th The e mining mining cy cycle cle with with gr grou

• utin

ting

Drill initial Probe holes Grout holes Drill verification probe holes Drill face charge holes Develop the tunnel Re-entry inspection Geological/geotechnical inspection and mapping Install ground support (bolts, mesh, shotcrete).

Inflows above specified levels?

Remove rock with gold

Y N

Inflows above specified levels?

Y N

Inflows above specified levels? Inflows above specified levels? Inflows above specified levels?

N Y Y N

Inflows above specified levels?

Y N N Y

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 33

Interest point - 1945 Government Report

• n 381 day BIH pump test in 1934

Government pump test 9th June 1934 – 13th July 1935 381 days at 4.4ML/day 11th November 1934 “Shear filled with altered slate in crosscut 35 ft. west of the shaft at the level responsible for increased flow. Shear enters shaft at 389 ft. 80% of water making in mine is in Victoria Shaft.”

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 34

Shotcrete

 Shotcrete is a sprayable cement product, often including small fibres and aggregate to improve strength properties, used to manage exposed ground conditions (i.e. on the surface of the excavation).  Applied to bare rock face and/or over already installed mesh and bolts.

http://bestsupportunderground.com/fibre-reinforced-shotcrete/?lang=en

 It does not penetrate the structure of the rock.  Can help seal minor groundwater inflows

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 35

What if – we developed the tunnel and inflows are larger than expected?

 Post-excavation grouting available to ‘seal off’ open fractures  Used modelling to see impact on surrounding bores of hitting fracture zone at both 130m below surface and 300m below surface  Impact showed 1-2m groundwater drawdowns after two weeks  Blue – 130m  Red – 300m  Reinjection still operating

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 36

• 3. Depressurisation and Managed Aquifer

Recharge

 Decreases pressure head above mine void  Increases effectiveness of grouting system

• Reduces risk of grouting failure

 Keeps water out of mine – take it out above mine before it enters and reinject around mine (radial)  Reinjection allows for the “cone of depression” to be very steep and narrow around mine  Together allows Terramin to operate without impacting groundwater supply to existing users

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 37

Snapshot - Seasonal Summer Drawdown

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 38

Differences with and without Reinjection

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 39

Reinjection bore locations

 Reinjection will be in a radial pattern around the mine workings  This makes the ‘cone’ very steep and narrow  Prevents impacts to

• perational bores in the

area – reinjection between mine and receptors  Prevents drawing in salt from Dawesley Catchment

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 40

Depressurisation and Reinjection

 Reinjection creates a higher water level

• utside the mine to

prevent impacts to

• ther uses

 Over 40 MAR systems in SA

Irrigation bores Reinjection bore Above mine

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 41

Water Quality of Receiving Environments

 Reinjection water must be of same quality as receiving environment

• Salinity
• Metals
• Nutrients

 Environment Protection (Water Quality) Policy 2015

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 42

Volumes from Modelling

Year 90% Grout 70% Grout ML/y ML/d L/s ML/y ML/d L/s 1 70.8 0.2 2.2 212.4 0.6 6.7 2 109.4 0.3 3.5 328.1 0.9 10.4 3 137.8 0.4 4.4 413.3 1.1 13.1 4 160.4 0.4 5.1 481.1 1.3 15.3 5 143.3 0.4 4.5 430.0 1.2 13.6

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 43

Groundwater Management Summary

 Built in capacity for water management contingencies  Strategies are designed to prevent water inflows from the fracture zone and manage water inflows  Probe drilling allows active and adaptive management  Allows actions before inflows become an issue  Grout will be applied to limit the water inflows into the underground workings – amount based on probe drilling result  Reinjection creates a pressure barrier that prevents impacts to other groundwater users

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 44

Groundwater Monitoring Network Conceptual

 Additional monitoring wells to be placed between receptors and reinjection:

• Private wells
• Inverbrackie Creek
• Dawesley Creek

catchment  High frequency monitoring of :

• Groundwater

seepage & quality

• Groundwater levels

& quality

• --- Reinjection bore network
• --- Monitoring bore network

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 45

Responding to Monitoring “Trigger Action Response Plans”

 A TARP provides early warning triggers and response actions for prevention of impacts to nearby water users  The monitoring program will be designed to:

• detect changes to groundwater levels, groundwater salinity &

inflow rates,

• indicate that an abnormal condition relating to mining has

developed  Trigger levels to be set for particular impacts at which a response is needed

• Baseline monitoring data provides guidelines for trigger levels

 Action - repeat monitoring, investigate cause, notify  Response – Review and implement management strategies in order to meet our obligations

TERRAMIN AUSTRALIA LIMITED

SLIDE No. 46

Conceptual Groundwater model Computer Groundwater model Groundwater Impact Assessment Independent review of conceptual and computer Groundwater models Assessment of water management

• ptions

Assessment of Project against Water Allocation Plan + Determination Develop Plan for Management and Monitoring

What’s Next?

 Modelling of 5 years of drought  5 years of above average rain  Additional monitoring bores installation  Ongoing monitoring of existing groundwater network  Approval from Government to drill and test reinjection bores  Review and update model with new information

Update with new information

We are here

Next meetings and close

Next Water TRG meeting WCCC governance working party Next WCCC meeting Great to meet you My very best wishes to you all

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