APPENDIX S: VISUAL IMPACT ASSESSMENT – B2018 PROJECT … · 2018-10-03 · 2.1 Visual Impact...

Appendix S

APPENDIX S: VISUAL IMPACT ASSESSMENT – B2018 PROJECT (TALIS CONSULTANTS)

Appendix S

B2018 Visual Impact Assessment Anticipated Landscape changes due to the Beyond 2018 Project Goldfields St Ives Gold Mine

Appendix Q October 2017 | Page 1

Assets | Engineering | Environment | Noise | Spatial | Waste

B2018 Visual Impact Assessment

Anticipated Landscape changes due to the Beyond 2018

Project

Prepared for Goldfields St Ives Gold Mine

October 2017

Project Number: TA17032


Appendix Q October 2017 | Page i

DOCUMENT CONTROL

Version Description Date Author Reviewer

0a Internal Review 16/10/17 FW NK/EV

0b Second Review 24/10/17 FW AM/EV

1a Released to Client 24/10/17 FW AM/EV

Approval for Release

Name Position File Reference

Andrew Mack Associate Director TA17032_VIA_Report.1a

Signature

Copyright of this document or any part of this document remains with Talis Consultants Pty Ltd and cannot be used,

transferred or reproduced in any manner or form without prior written consent from Talis Consultants Pty Ltd.


Appendix Q October 2017 | Page ii

Table of Contents 1 Introduction ............................................................................................................................................ 1

1.1 Background ........................................................................................................................................... 1

1.2 Project Scope ........................................................................................................................................ 1

1.3 Study Area ............................................................................................................................................. 1

2 Methods .................................................................................................................................................. 5

2.1 Visual Impact Simulations ..................................................................................................................... 5

2.1.1 Preparation of Digital Elevation Models ................................................................................ 5

2.1.2 Selection of Viewpoints ....................................................................................................... 10

2.1.3 Viewshed Analysis ................................................................................................................ 12

2.1.4 Photomontage Analysis ....................................................................................................... 13

3 Results ................................................................................................................................................... 18

3.1 Viewshed Analysis ............................................................................................................................... 18

3.2 Photomontage Analysis ...................................................................................................................... 24

4 Discussion ............................................................................................................................................. 29

4.1 Mitigation Strategies ........................................................................................................................... 29

4.2 Recommendations .............................................................................................................................. 29

5 Conclusion ............................................................................................................................................. 30

References ..................................................................................................................................................... 31

Figures Figure 1: B2018 Locality Map

Figure 2: Conservative Development Scenario for B2018 Project

Figure 3: Baseline Digital Elevation Model

Figure 4: B2018 Digital Elevation Model

Figure 5: Baseline 3D Model of Development Envelope


Appendix Q October 2017 | Page iii

Figure 6: B2018 3D Model of Development Envelope

Figure 7: Location of Viewpoints

Figure 8: Viewshed Analysis Concept Model

Figure 9: Viewpoint 1 – Red Hill Carpark East

Figure 10: Viewpoint 2 – Red Hill Carpark South

Figure 11: Viewpoint 3 – Red Hill Lookout

Figure 12: Viewpoint 4 – BHP Dam

Figure 13: Viewpoint 5 – Salt works

Figure 14: Viewshed Distance / Elevation Concept

Figure 15: Red Hill Carpark East Viewshed

Figure 16: Red Hill Carpark South Viewshed

Figure 17: Red Hill Lookout Viewshed

Figure 18: BHP Dam Viewshed

Figure 19: Saltworks Viewshed

Figure 20: Viewpoint 1 – Red Hill Carpark East Photomontage

Figure 21: Viewpoint 2 - Red Hill Carpark South Photomontage

Figure 22: Viewpoint 3 – Red Hill Lookout Photomontage

Figure 23: Viewpoint 3 – Red Hill Lookout Photomontage with 40m WRLs

Figure 24: Viewpoint 5 – Salt works Photomontage



1 Introduction

1.1 Background

St Ives Gold Mining Company Pty Ltd (SIGMC) is presently undertaking a number of planning and approvals

processes to ensure the continued and ongoing operation of its gold mining operations on and around Lake

Lefroy in the Goldfields region of Western Australia (WA).

These processes are collectively named the Beyond 2018 Project. The B2018 Project will require an expansion

outside of the existing approved disturbance footprint under the Ministerial Statement 879 with the aim to

provide sufficient ore reserves to facilitate mining for a ten year period (i.e. to 2028). A component of this project

is to determine the overall impact of mining on the landscape, and one method of assessing such an impact is

to undertake a Visual Impact Assessment (VIA).

A VIA depicts the ‘before and after’ snapshot of mining operations over a given period. It visually represents

anticipated changes to the landscape, and suggests how visible those changes will be from key observation

points, such as nearby roads and towns.

1.2 Project Scope

The purpose of this assessment was to identify potential visual impacts associated with mining activities around

the Lake Lefroy area. The objectives of the study were to:

1. Identify key surrounding observation points

2. Calculate anticipated Beyond 2018 landscape changes

3. Determine visibility of landscape changes from observation points

4. Assess the significance, in terms of visual impact, of anticipated landscape changes

5. Propose mitigation measures, where possible, to minimise negative visual impacts

1.3 Study Area

Mining at St Ives Gold Mine (St Ives) comprises both lake and land-based development and is located in the Gold

Fields region of WA, approximately 55km south of Kalgoorlie adjacent to the town of Kambalda (Figure 1).

The proposed B2018 Project will facilitate continuation of mining operations associated with Lake Lefroy and

the wider St Ives site. The Development Envelope encompasses approximately 45,000 hectares (ha) and whilst

a defined project area is still being developed, it is expected to have a disturbance footprint of approximately

5,000ha across a 10-year operational period. The maximum proposed disturbance of 5,000 ha consists of:

Lake based disturbance up to 200 ha per year over a ten year period with a total maximum disturbance

of up to 2,000 ha; and

Land based disturbance up to 300ha per year over a ten year period with a total maximum disturbance

of up to 3,000 ha.

These limits are seen as the upper thresholds for disturbance and may be reduced as studies are completed and

where areas of particular environmental value are identified and determined to warrant protection through

avoidance.

The proposed disturbance results in up to 9,146 ha of total disturbance consisting of 4,061 ha of lake disturbance

and 5,085 ha of land disturbance within the Development Envelope (refer to Figure 1).



For the purpose of this VIA, a conservative worst-case scenario mining plan was created to assess the impacts

to environment and landscape. The map showing indicative locations of pits and waste rock landforms (WRL)

(Figure 2) was agreed in co-operation with SIGMC and is subject to change once further resource definition takes

place. VIA was undertaken over the whole of Development Envelope.



Figure 1: B2018 Locality Map



Figure 2: Conservative Development Scenario for B2018 Project



2 Methods

2.1 Visual Impact Simulations

2.1.1 Preparation of Digital Elevation Models

High resolution (40cm interval) elevation data was acquired over the B2018 Development Envelope in November

2016. This data was gridded at 4m resolution, and used as the baseline Digital Elevation Model (DEM) to assess

simulated visual impacts of existing operations. The existing Santa Ana and Neptune operations are

representative of the two types of future mining activities that may occur within the Development Envelope.

Santa Ana operation represents a typical lake based operation and Neptune operation was used as a model for

land based operations. The impact of these operations on the terrain was replicated at each of the proposed

mining locations, depending on their proposed type (Santa Ana or Neptune). This was completed by cutting the

existing terrain from the operational area, and replacing it with the appropriate type elevation model. This was

trivial for operations proposed to occur on Lake Lefroy, where the surrounding terrain is largely flat. For the

land-based operations, the elevation of the type model was shifted vertically in order to best fit the median

elevation of the landscape surrounding the proposed operation.

It should be noted that this approach to generating the B2018 DEM represents a more significant impact on the

landscape than is likely and represents the worst case scenario – it assumes that all the proposed operations

proceed, that all operations will include a WRL of ~20m height above the surrounding terrain, and that they will

all occur simultaneously. In reality, the development is expected to be staged over a decade, allowing for

progressive rehabilitation including backfilling of sterilised pits. Backfilling will eliminate the need for WRL

construction and the resulting number of WRLs is likely to be reduced from what was assessed as part of this

VIA.

It was assumed that a 20 m WRL represents an average WRL across the SIGMC operations but for the purposes

of the VIA, an assessment for a 40 m high WRLs was also undertaken.

Figure 3 and Figure 4 show the Baseline and B2018 DEMs.

In order to generate a realistic model of the current and proposed landscapes, aerial photography was used to

overlay the DEMs. For the Baseline model, high resolution (20cm interval) aerial photography acquired in 2016

was used to overlay the DEM. For the B2018 model, the aerial image was edited to reflect the proposed

operations, with the Santa Ana and Neptune operations aerial images pasted over the proposed operations as

appropriate.

Figure 5 and Figure 6 show the Baseline and B2018 3D models, with a 5x vertical exaggeration.



Figure 3: Baseline Digital Elevation Model



Figure 4: B2018 Digital Elevation Model



Figure 5: Baseline 3D Model of Development Envelope



Figure 6: B2018 3D Model of Development Envelope



2.1.2 Selection of Viewpoints

Key viewpoints were identified by SIGMC staff, and these sites were visited on 12th August 2017. Each site was

captured with a series of photographs, and the GPS location of each site recorded. The sites included:

1. Red Hill Carpark East;

2. Red Hill Carpark South;

3. Red Hill Lookout;

4. BHP Dam; and

5. Salt works.

These sites were selected on the basis that they are visible or accessible via public roads, they may attract

tourists or are considered to represent a landscape that is typical for the Goldfields region.

Figure 7 shows the location of each viewpoint, as well as the azimuth range of the series of photographs taken

at each site.



Figure 7: Location of Viewpoints



2.1.3 Viewshed Analysis

A viewshed is an area that is visible from a specific location. Viewshed analysis is the method for determining

the visibility from a given point, using the elevation model of the surrounding landscape. Using this method,

items on the landscape that do not form part of the DEM, such as sparse vegetation, will not be considered to

impact the visibility. Additionally, any impact from dust or haze obscuring the landscape will not affect the

analysis. The analysis is limited to the extent of the DEM, and takes the curvature of the earth into consideration.

Viewsheds for each viewpoint were calculated using the baseline and B2018 DEMs, in order to determine the

impact on visibility of the B2018 Project. The output of the analysis is a binary layer, with values representative

of either visible, or not visible, from the viewpoint. Through manipulation of the two viewsheds for each point,

the view of the terrain can be classified as:

a. Always visible

b. Made visible by B2018 operations

c. Obscured by B2018 operations

d. Always obscured.

This concept is illustrated in Figure 8.

Figure 8: Viewshed Analysis Concept Model

Specific parameters used during the viewshed analysis are given in Table 2-1.

Table 2-1: Parameters used for Viewshed Analysis

Parameter Type Explanation Parameter Value Used

Search Radius (distance) Size of the analysed area around each viewpoint 35km

Search Radius (angle) Angle of the analysed area around each viewpoint 360

Observer Height Height above ground from which the analysis is made 1.8m

Atmospheric Refraction Coefficient used to calculate the bending of light due

to the atmosphere 0.13



2.1.4 Photomontage Analysis

A photomontage is a visual representation of the proposed development. It aims to illustrate what the B2018

operations will look from a specified viewpoint, by superimposing a 2D model of the changes to the landscape

over a photograph of the landscape taken prior to the changes occurring. The photomontage analysis

incorporates the vegetation and other screening objects (such as signs and powerpoles) that were either too

small or sparse to be captured in the elevation model, or were edited out of the DEM (which aims to represent

ground-level elevation). This allows a realistic view of the changes to the landscape from the observation point.

The series of photographs taken at each viewpoint were stitched together to form a panorama, and these

outputs were used in the photomontage analysis. 3D models of the DEM, focussed on the aspect of each

viewpoint, were generated to illustrate the changes to the landscape at each viewpoint. Photo editing software

was then used to alter the panoramic photographs to insert the proposed landform features.

For the purposes of the photomontage analysis, a 20m high WRL has been assumed to represent an average

WRL across the SIGMC operations. Impact of increasing the height of the WRL to 40m was also considered.

The panoramic photographs are presented in Figure 9 to Figure 13.



Figure 9: Viewpoint 1 – Red Hill Carpark East



Figure 10: Viewpoint 2 – Red Hill Carpark South



Figure 11: Viewpoint 3 – Red Hill Lookout

Figure 12: Viewpoint 4 – BHP Dam



Figure 13: Viewpoint 5 – Salt works



3 Results

3.1 Viewshed Analysis

The viewsheds for the five viewpoints are shown in Figure 15 to Figure 19.

The viewsheds for the Red Hill locations show similar results, as these viewpoints were in close geographical

proximity (within 300m of each other), and at a similar elevation (range of 5m). As expected from an elevated

position, the proposed B2018 WRLs close to the viewpoint locations obscure less of the surrounding landscape

than those WRLs at a further distance. This is because an observer at an elevated location would be able to see

over the nearest proposed WRLs. This concept is explained in Figure 14.

Figure 14: Viewshed Distance / Elevation Concept

The viewsheds for the BHP Dam and Salt works viewpoints show that a large portion of the Development

Envelope is always obscured. This is due to the low elevation of these points with respect to the surrounding

landscape features.



Figure 15: Red Hill Carpark East Viewshed



Figure 16: Red Hill Carpark South Viewshed



Figure 17: Red Hill Lookout Viewshed



Figure 18: BHP Dam Viewshed



Figure 19: Saltworks Viewshed



3.2 Photomontage Analysis

The results of the photomontage analysis are presented in Figure 20 to Figure 24. The photomontages use the

colour scheme from the aerial photography for the inserted landforms. This presents a realistic view of the

changes to the landscape.

From the elevated viewpoints (Red Hill Carpark East, Red Hill Carpark South and Red Hill Lookout), the changes

to the landscape are obvious. However, from the less elevated viewpoints (BHP Dam and Salt works), the visual

impacts are minimal. At BHP Dam, there were no visible changes to the landscape due to the proposed

operations being obscured by existing landforms.

Based on the photomontage analysis the changes in the landscape are only visible on the lake. Changes to land-

based operations are not evident as these are too far away from the viewpoints and screened by the existing

vegetation.

Increase of WRL height from 20 m to 40 m does not appear to have a significant impact on the landscape (refer

to Figure 22 and Figure 23) although changes to the viewshed as a result of the increase are likely to be more

evident.



Figure 20: Viewpoint 1 – Red Hill Carpark East Photomontage



Figure 21: Viewpoint 2 - Red Hill Carpark South Photomontage



Figure 22: Viewpoint 3 – Red Hill Lookout Photomontage

Figure 23: Viewpoint 3 – Red Hill Lookout Photomontage with 40m WRLs



Figure 24: Viewpoint 5 – Salt works Photomontage



4 Discussion

4.1 Mitigation Strategies

VIA undertaken shows that from the elevated viewpoints (Red Hill Carpark East, Red Hill Carpark South and Red

Hill Lookout), the changes to the landscape are obvious. However, implementation of the B2018 Project does

not change the nature of the landscape, it only adds features that have been part of the landscape since the

beginning of gold mining operations on Lake Lefroy in early 1980s (Gold Fields Limited 2013).

In order to mitigate impacts to the landscape, SIGMC should endeavour to design and site the mining

infrastructure to minimise the viewshed and other impacts to landscape. This may involve placement of

infrastructure areas behind the higher landforms such as WRLs so infrastructure areas are not visible from the

elevated viewpoints, or limiting the height of WRLs. This is not always possible due to the size and location of

the resource and consequently higher emphasis should be on progressive rehabilitation.

Rehabilitation is one of the key components of mine closure. Progressive rehabilitation allows for backfilling of

sterilised pits which consequently reduces the need for WRLs which are considered to have the largest impact

on the existing landscape. SIGMC’s current rehabilitation strategy for lake-based WRLs involves rock armouring

to ensure safe and stable landforms. No topsoil addition and seeding are generally used. Early and progressive

rehabilitation ensures that any features on lake are rehabilitated to their final closure design as soon as

practicable.

Land-based operations are not expected to be visible from areas that are accessible by the public. Closure of

land-based features will be undertaken in accordance with the Mine Closure Plan focusing on revegetation which

will reduce the prominence of constructed features.

4.2 Recommendations

By evaluating the mitigation strategies a set of recommendations can be proposed. As expected the largest

impact to the landscape and visual impact can be observed from the elevated viewpoints. In general the

progressive rehabilitation will have the largest impact on the landscape during the operation as well as after

closure. It is recommended that the following will be considered during the operation and closure of B2018

Project:

Siting and design of mining infrastructure to make it more visually pleasing;

Using higher features such as WRLs as screens for other mining infrastructure; and

Progressive rehabilitation involving backfilling of sterilised pits and rehabilitation WRLs as soon as

practicable.



5 Conclusion

The VIA was undertaken for the proposed B2018 operations to assess the impacts of the project to existing

landscape and visual amenity. The assessment utilised view shed and photomontage analysis and the viewpoints

for the analysis were chosen on the basis that they are visible or accessible via public roads, they may attract

tourists or are considered to represent a landscape that is typical for the Goldfields region.

The results of the analysis show that from the elevated viewpoints (Red Hill Carpark East, Red Hill Carpark South

and Red Hill Lookout), the changes to the landscape are obvious. However, from the less elevated viewpoints

(BHP Dam and Salt works), the visual impacts are minimal.

In order to minimise the impacts to landscape and visual amenity SIGMC should consider optimising the siting

and design of mining infrastructure and using existing or proposed features as screens for less visually pleasing

infrastructure. For any features that are proposed to be a permanent part of the landscape, progressive

rehabilitation should be undertaken. This may involve pit backfilling and progressive rehabilitation of WRLs.



References Gold Fields Limited. 2013. Gold Fields in the Goldfields - A short history of Gold Fields in Australia.

APPENDIX S: VISUAL IMPACT ASSESSMENT – B2018 PROJECT … · 2018-10-03 · 2.1 Visual Impact...

Documents

Transcript of APPENDIX S: VISUAL IMPACT ASSESSMENT – B2018 PROJECT … · 2018-10-03 · 2.1 Visual Impact...