Original EA Amendment

Executive summary .......................................................... iii

Table of contents

1

Project Background ................................................ 1

1.1

Introduction................................................................................ 1

1.2

Site description.......................................................................... 1

1.3

TSF characteristics ................................................................... 2

1.4

Receiving environment ............................................................. 2

2

Dam failure overview............................................... 5

2.1

Dam failure mechanisms .......................................................... 5

2.2

Sunny day and flood day scenarios ........................................ 6

2.3

Breach locations........................................................................ 6

2.4

Flow behaviour .......................................................................... 6

2.5

Flood severity classification .................................................... 7

2.6

Downstream modelling extents ............................................... 8

3

Failure scenarios ..................................................... 9

3.1

Failure mechanisms .................................................................. 9

3.2

Failure location .......................................................................... 9

3.3

Background flood .................................................................... 11

3.4

Initial conditions ...................................................................... 11

3.5

Overview of considered failure scenarios ............................ 11

4

Dam break characterisation ................................. 12

4.1

Outflow volumes...................................................................... 12

4.2

Dam Break parameters ........................................................... 16

4.3

Outflow hydrographs .............................................................. 17

5

Hydraulic modelling .............................................. 20

5.1

Modelling Approach and Inputs............................................. 20

5.2

Hydraulic modelling results ................................................... 20

5.2.1 5.2.2

Inundation mapping ..............................................................................20 Summary of simulation results..............................................................21

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