Works Approval

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Prescribed premises category description

(Schedule 1, Environmental Protection Regulations 1987)

Assessed production / design capacity

Category 12: Screening, etc. of material 3,500,000 tonnes per annual

period

Category 52: Electric power generation 854 MWe per annual period

Category 53: Flyash disposal 200,000 tonnes per annual period

Category 61: Liquid waste facility 3,285,000 tonnes per annual

period

This works approval is granted to the works approval holder, subject to the attached conditions, on 26 May 2020, by:

Manager Licensing, Process Industries

an officer delegated under section 20 of the Environmental Protection Act 1986 (WA) Works approval number W6321/2019/1

Works approval holder Electricity Generation and Retail Corporation T/A Synergy

Registered business address Forrest Centre

219 St Georges Terrace PERTH WA 6000 DWER file number DER2019/000543

Duration 27 May 2020 to 26 May 2023

Date of issue 26 May 2020

Premises details

Muja Power Station Muja Power Station Road COLLIE WA 6225

Legal description -

Being Lot 5192 on Plan 213624, part Lot 4903 on Plan 167984, Lot 1 on Diagram 53100 and portion of State Forest 24

As defined in Schedule 1 of the Works Approval

Works Approval

Caron Goodbourn

Digitally signed by Caron Goodbourn

Date: 2020.05.26 16:30:03 +08'00'

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Interpretation

In this works approval:

(a) the words ‘including’, ‘includes’ and ‘include’ in conditions mean “including but not limited to”, and similar, as appropriate;

(b) where any word or phrase is given a defined meaning, any other part of speech or other grammatical form of that word or phrase has a corresponding meaning;

(c) where tables are used in a condition, each row in a table constitutes a separate condition;

(d) any reference to an Australian or other standard, guideline, or code of practice in this works approval:

(i) if dated, refers to that particular version; and

(ii) if not dated, refers to the latest version and therefore may be subject to change over time;

(e) unless specified otherwise, any reference to a section of an Act refers to that section of the EP Act; and

(f) unless specified otherwise, all definitions are in accordance with the EP Act.

NOTE: This works approval requires specific conditions to be met but does not provide any implied authorisation for other emissions, discharges, or activities not specified in this works approval.

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Works approval conditions

The works approval holder must ensure that the following conditions are complied with:

Infrastructure and equipment The works approval holder must:

(a) construct and/or install the infrastructure and/or equipment;

(b) in accordance with the corresponding design and construction / installation requirements; and

(c) at the corresponding infrastructure location.

as set out in Table 1.

Table 1: Design and construction / installation requirements

Infrastructure Design and construction / installation requirements Infrastructure location 1. Embankment  Cell 1B raised to RL 261m AHD

 Outer slopes shaped to 1Verticle:3Horizontal

 Zone 1 (clayey fill) intended to act as a low permeability hydraulic barrier. Zone 1 will be used to encapsulate the bottom ash on the downstream face of the existing embankment.

Additional erosion protection is not included.

 Constructed to allow for a maximum 500mm freeboard. Total freeboard measured from spillway level to maximum pond operating level

 Toe drain along the downstream embankments conveys uncontaminated stormwater away from the embankments to collection sumps and discharges to the environment via reinforced concrete pipes, under the access road

 The underdrainage system diverts leachate to one of two collection chambers, a west chamber and a south east chamber and to designated collection tanks. Leachate is then pumped back into Cell 1B.

 4 x new piezometers placed around the external perimeter embankment crest

 1 x new piezometer placed in the internal perimeter embankment in between Cell 1 and Cell 2 (divider wall)

 Constructed using in-situ soils and bottom ash.

In-situ soils rolled and compacted to a minimum 95% of Standard Maximum Dry Density and placed within a moisture content tolerance of within 2% (+/-) of its optimum moisture content.

 Crests with a 2% slope with a 5m width (minimum 3.5m trafficable width) and 500mm

Figure 3, Figure 4, Figure 8, Figure10, Figure 11 and

Figure 13

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4 Infrastructure Design and construction / installation requirements Infrastructure

location windrow.

 Access ramps 5m wide with slope 1Verticle:10Horizontal (minimum 3.5m trafficable width) and 500mm windrow.

2. Spillway  20m wide x 300mm deep spillway invert level of RL 260.7m)

 Spillway crest and channel to be covered by 150mm of rock protections.

Figure 3 and Figure 11

3. Underdrainage  2 x DN160 slotted draincoil pipes located in the existing toe drain alignment with Zone 2A and Zone 2B filter material surrounding them

 2 x underdrainage collection locations: 1 x new sump in the NW corner of Cell 1; and 1 x existing sump and collection tanks located to the south of Cell 1.

Figure 5, Figure 6, Figure, 7 and Figure 9

4. Decant

structures  2 x vertical slotted well-liner type precast DN 1800 concrete pipes raised approximately 1m above the Cell 1 and Cell 2 divider wall

 Recovered water will be recycled back towards the supernatant pond

Figure 3 and Figure 12

5. Pipelines  To be fitted with automatic leak detection and shut off systems to minimise discharge and allow for maintenance and recovery of materials

NA

6. Stormwater collection and diversion system

 Toe drains, culverts and collection pits to be maintained and cleared of debris

Figure 8

7. Flyash deposition ring main

 A perimeter ring main fitted with multiple spigot discharge outlets

NA

Compliance reporting

The works approval holder must within 90 calendar days of an item of infrastructure or equipment required by condition 1 being constructed and/or installed:

(a) undertake an audit of their compliance with the requirements of condition 1;

(b) undertake an audit of compliance of condition 1 with the requirements of Muja Cell 1B FAD Raise – Detailed Design 612145927-REP-0_Design Report Revison 0 (GHD, October 2019);

(c) undertake an audit of compliance of condition 1 with the requirements of Guidelines on tailings dams: Planning, design, construction, operation and closure (ANCOLD, 2019); and

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5 (d) prepare and submit to the CEO an Environmental Compliance Report on that

compliance.

The Environmental Compliance Report required by condition 2, must include as a minimum the following:

(a) certification by a suitably qualified and experienced geotechnical specialist that the items of infrastructure or component(s) thereof, as specified in condition 1, have been constructed in accordance with the relevant requirements specified in condition 2;

(b) as constructed plans and a detailed site plan for each item of infrastructure or component of infrastructure specified in condition 1;

(c) Where a departure from the requirements specified in Condition 2 occurs, the Licence Holder must provide to the CEO a description of, and explanation for, the departure; and

(d) be signed by a person authorised to represent the works approval holder and contains the printed name and position of that person.

The Works Approval Holder shall undertake an annual audit of the Fly Ash Dam materials characteristics and performance attributes against the assumed design parameters in accordance with Tailings storage facility audit- guide (Department of Mines, Industry Regulation and Safety, 2017) within 12 months of the issue date of this Works Approval.

Records and reporting

The works approval holder must record the following information in relation to complaints received by the works approval holder (whether received directly from a complainant or forwarded to them by the Department or another party) about any alleged emissions from the premises:

(a) the name and contact details of the complainant, (if provided);

(b) the time and date of the complaint;

(c) the complete details of the complaint and any other concerns or other issues raised; and

(d) the complete details and dates of any action taken by the works approval holder to investigate or respond to any complaint.

The works approval holder must maintain accurate and auditable books including the following records, information, reports, and data required by this works approval:

(a) the works conducted in accordance with condition 1;

(b) any maintenance of infrastructure that is performed in the course of complying with condition 1;

(c) complaints received under condition 5.

The books specified under condition 6 must:

(a) be legible;

(b) if amended, be amended in such a way that the original version(s) and any subsequent amendments remain legible and are capable of retrieval;

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6 (c) be retained by the works approval holder for the duration of the works approval;

and

(d) be available to be produced to an inspector or the CEO as required.

Definitions

In this works approval, the terms in Table 1 have the meanings defined.

Table 1: Definitions

Term Definition

books has the same meaning given to that term under the EP Act.

CEO means Chief Executive Officer.

CEO for the purposes of notification means:

Director General

Department administering the Environmental Protection Act 1986

Locked Bag 10

Joondalup DC WA 6919 info@dwer.wa.gov.au

Department means the department established under section 35 of the Public Sector Management Act 1994 and designated as responsible for the administration of Part V Division 3 of the EP Act.

discharge has the same meaning given to that term under the EP Act.

emission has the same meaning given to that term under the EP Act.

Environmental Compliance Report

means a report to satisfy the CEO that the conditioned infrastructure and/or equipment has been constructed and/or installed in accordance with the works approval.

EP Act Environmental Protection Act 1986 (WA).

EP Regulations Environmental Protection Regulations 1987 (WA).

premises the premises to which this licence applies, as specified at the front of this licence and as shown on the premises map (Figure 1) in Schedule 1 to this works approval.

prescribed premises

has the same meaning given to that term under the EP Act.

suitably qualified and experienced geotechnical specialist

means a person who:

(a) holds an engineering degree; and

(b) has a minimum of at least three years of experience working in the area / field of geotechnical assessment of tailings storage facilities or fly ash dams.

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Term Definition

works approval refers to this document, which evidences the grant of the works approval by the CEO under section 54 of the EP Act, subject to the conditions.

works approval holder

refers to the occupier of the premises being the person to whom this works approval has been granted, as specified at the front of this works approval.

_________________________________________________________________________

END OF CONDITIONS

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Schedule 1: Maps

Premises map

The boundary of the prescribed premises is shown in red in the map below

Figure 1: Muja Power Station Premises Boundary

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9 Figure 2: Fly Ash Dam cell layout

Source: Report for Synergy – Generation Business Unit – Muja Cell 1B FAD Raise – Detailed Design Appendix H Drawing Number M127/C/43/1 (GHD, 2019)

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10 Figure 3:Cell 1B embankment raise layout

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11 Figure 4: Cell 1B underdrainage location map

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12 Figure 5: Cell 1 B underdrainage system details – west chamber

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13 Figure 6: Cell 1 B underdrainage system details – south east chamber

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14 Figure 7: Cell 1 B underdrainage system details – pipe invert box below extsing toe drain

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15 Figure 8: Cell 1 B Toe drain and stormwater collectionn pit system details

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16 Figure 9: Cell 1 B underdrainage system longitutdinal section

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17 Figure 10: Cell 1 B embankment raise emabkment and crest detail

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18 Figure 11: Cell 1 B spillway plan and section

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19 Figure 12: Cell 1 B Embankment raise dividing wall and decant structure cross section

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20 Figure 13: Cell 1 B peizometer arrangement and detail