Little Paddock Gold Mine Extension

LITTLE PADDOCK GOLD MINE EXTENSION

Assessment of Noise Effects

Rp 001 R01 2013232C

16 July 2013

Level 3 69 Cambridge Terrace

PO Box 4071

Christchurch 8140 New Zealand

T: +64 3 365 8455 F: +64 3 365 8477

www.marshallday.com

Project: LITTLE PADDOCK GOLD MINE EXTENSION

Prepared for: Gold and Green Resources Ltd

PO Box 11

Hokitika 7842

Attention: John Wood

Report No.: Rp 001 R01 2013232C

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Document control

Status: Rev: Comments Date: Author: Reviewer:

Approved - - 12 July 2013 Aaron Staples Stuart Camp

Approved R01 Additional dwellings and

wheeled loader 16 July 2013 Aaron Staples Stuart Camp

This document may not be reproduced in full or in part without the written consent of Marshall Day Acoustics Limited

Rp 001 R01 2013232C Little Paddock Gold Mine Extension ANE of 17

EXECUTIVE SUMMARY

Marshall Day Acoustics has assessed potential noise effects from a proposed extension to the Little

Paddock gold mining activity at Blue Spur, near Hokitika. The proposed extension involves utilising

additional plant and equipment and changing the order in which the mine sites will be mined.

We have predicted noise levels at surrounding noise sensitive receivers and confirm that

compliance with the District Plan daytime noise rules can be achieved, provided that the following

noise mitigation measures are implemented:

• Mining activity on site shall only be undertaken between 0700-2100 hours, Monday to Friday,

and 0700-1800 hours on Saturdays;

• All mining equipment must maintain a set back distance of no less than 150 metres from the

nearest façade of dwellings labeled ‘D’ and ‘E’ in Figure 1;

• In the event that a dwelling is constructed on the subdivision to the south of the mine site,

either one of the following noise mitigation measures must be implemented:

1) All mining equipment must maintain a set back distance of at least 100 metres from the

southern boundary of the mine site; or

2) All mining equipment must maintain a set back distance of at least 25 metres from the

southern boundary of the mine site, and earth bunds no less than 3 metres high must be

constructed along the mine site boundary as indicated with a blue line on the noise

contour map for Scenario 2b (Appendix B).

• Mining operations shall utilise the best practicable option to minimise noise at all times. This

includes regular maintenance and replacement of worn parts, maintenance of mufflers,

lubrication of all moving parts to avoid squeaks and squeals, and appropriate operation of all

equipment.

Provided that the above measures are implemented, we anticipate that any noise effects that may

arise from the proposal will be acceptable.



TABLE OF CONTENTS

1.0 INTRODUCTION ........................................................................................................................ 5

2.0 SITE & ACTIVITY DESCRIPTION ................................................................................................ 5

3.0 NOISE ASSESSMENT CRITERIA ................................................................................................. 7

3.1 District Plan Noise Rules .......................................................................................................... 7

3.2 World Health Organisation ...................................................................................................... 7

3.3 NZS 6802:2008 Guideline Upper Noise Limits ....................................................................... 8

3.4 Discussion of Noise Assessment Criteria ................................................................................ 8

4.0 NOISE LEVEL PREDICTION METHODOLOGY ........................................................................... 8

4.1 Input Noise Source Levels ........................................................................................................ 8

5.0 PREDICTED NOISE LEVELS ........................................................................................................ 9

6.0 ASSESSMENT OF NOISE EFFECTS .......................................................................................... 10

6.1 Existing Dwellings ................................................................................................................... 10

6.2 Subdivision South of Mine Site .............................................................................................. 10

7.0 RECOMMENDATIONS ............................................................................................................ 11

8.0 CONCLUSIONS ........................................................................................................................ 11

APPENDIX A GLOSSARY OF TERMINOLOGY

APPENDIX B NOISE CONTOUR MAPS



1.0 INTRODUCTION

Marshall Day Acoustics has been appointed by Gold and Green Resources Ltd on behalf of

Zalas Creek Mining Ltd to perform an assessment of noise effects for a proposed extension

of the Little Paddock gold mine in Blue Spur, near Hokitika. Marshall Day Acoustics prepared

the original noise assessment for the mine in 2011 (report reference Rp 001 2011358C,

dated 10 October 2011).

This report provides:

• A summary of the proposed mine extension in regard to noise generation;

• A review of appropriate noise assessment criteria;

• Predicted noise levels from the proposed mining operation; and

• An assessment of the potential noise effects at surrounding properties as a result of the

activity.

A glossary of the terminology used in this report is provided in Appendix A.

2.0 SITE & ACTIVITY DESCRIPTION

The Little Paddock gold mine site is located off Blue Spur Road, near Hokitika. The original

Little Paddock gold mine consent, granted in 2011, was to mine the area labelled Mining

Permit 53214 in Figure 1. The original proposal involved two excavators, one dump truck, a

trommel plant and a diesel powered dewatering pump. We understand that the West Coast

Regional Council had specified that ‘Mine Site 2’ (refer to Figure 1) be mined prior to ‘Mine

Site 1’ as part of the original consent.

The proposed mining extension involves utilising additional plant and equipment including

an additional dump truck, excavator, wheeled loader, trommel plant and dewatering pump.

The proposal also seeks to remove the requirement on the order in which the mine sites are

mined, so that ‘Mine Site 1’ can be mined prior to or at the same time as ‘Mine Site 2’. The

additional fixed plant (i.e. trommels and dewatering pumps) and wheeled loader will

operate in the same general location as the existing plant (near ‘Mine Site 1’) and will

benefit from screening provided by existing earth bunds constructed as part of the original

consent.

Hours of operation will continue to be 0700 to 1800 hours Monday to Friday and 0700 to

1200 hours on Saturdays. No mining will take place on Sundays or public holidays.

The dwellings nearest the mine site are indicated in Figure 1. The approximate extent of a

residential subdivision to the south of the mine site is also indicated, however, no dwellings

have been constructed on this land to date. We note that written approval was obtained

from the owners of dwellings D, E and F for the original consent and we understand that

approval could again be obtained if required.



Figure 1: Mine site and locality



3.0 NOISE ASSESSMENT CRITERIA

It is useful to consider a number of guidance documents in assessing the potential for noise

effects. These documents are discussed in the following sections.

3.1 District Plan Noise Rules

The mine site and surrounding land is zoned Rural under the Westland District Plan. The

District Plan noise rules applicable to the operation of the gold mine are as follows:

Noise

(all activities except forestry, and agricultural activities)

0700 – 2100 hrs Mon – Fri

0700 – 1800 hrs Saturday

55 dB LA10 at any point within the notional

boundary of a residential activity.

All other times including

public holidays

45 dB LA10 at any point within the notional

boundary of a residential activity.

As the mining activity will only operate during daytime hours on Monday to Saturday, the

critical noise limit is 55 dB LA10 at the notional boundary of a residential activity.

3.2 World Health Organisation

World Health Organisation (WHO) Guideline Values for Community Noise (Berglund and

Lindvall, 1999) give guidelines for environmental noise exposure. For community or

environmental noise, the critical health effects (those effects which occur at the lowest

exposure levels) are sleep disturbance and annoyance.

These Guideline Values are the exposure levels that represent the onset of the effect for the

general population.

Table 1: WHO Guideline Values for the critical health effects of community or environmental noise

Specific

Environment

Critical health effect(s) LAeq dBA Time base

(hours)

LAmax dBA

Outdoor living

area

Serious annoyance, daytime & evening

Moderate annoyance, daytime &

evening

55

50

16

16

-

-

Outside

bedrooms

Sleep disturbance, window open

(outdoor values) night-time

45 8 60



3.3 NZS 6802:2008 Guideline Upper Noise Limits

The 2008 version of NZS 6802:2008 “Acoustics - Environmental Noise” (N.B. the District Plan

refers to the 1991 version) provides the following guideline upper noise limits for noise

received at or within the notional boundary of any rural dwelling:

• Daytime: 55 dB LAeq(15min)

• Night-time: 45 dB LAeq(15min) and 75 dB LAFmax

3.4 Discussion of Noise Assessment Criteria

The District Plan noise rules are consistent with the WHO Guideline Values and the guideline

upper noise limits provided in the latest version of NZS 6802. We therefore consider that

compliance with the District Plan noise rules at surrounding dwellings will result in

acceptable noise effects.

4.0 NOISE LEVEL PREDICTION METHODOLOGY

To accurately predict noise levels, the noise modelling package SoundPLAN has been used.

Calculations in SoundPLAN are based on ISO 9613-2:1996 “Acoustics – Attenuation of sound

during propagation outdoors – Part 2: General method of calculation”. This method has the

scope to take into account a range of factors affecting the sound propagation including:

• The magnitude of the noise source in terms of sound power;

• The distance between source and receiver;

• The presence of obstacles such as screens or barriers in the propagation path;

• The presence of reflecting surfaces;

• The hardness of the ground between the source and receiver;

• Attenuation due to atmospheric absorption; and

• Meteorological effects such as wind gradient, temperature gradient and humidity.

In ISO 9613, the effect of meteorological conditions is significantly simplified by calculating

the average downwind sound pressure level. The Standard adopts the conservative

approach of assuming that wind is always blowing from the noise sources to the receiver

locations. The equations and calculations also hold for average propagation under a well

developed moderate ground based temperature inversion, such as commonly occurs on

clear, calm nights.

4.1 Input Noise Source Levels

Input noise source data has been based on noise level measurements of similar plant and

equipment operating at other gold mining and gravel extraction operations around New

Zealand. We have used the following sound power levels for the basis of our predictions.



Table 2: Sound power levels of mining noise sources used in model

Noise source Sound power level (dB LAw)

Trommel plant (each) 106

Diesel dewatering pump 103

Sykes dewatering pump 94

Excavator (each) 105

Wheeled loader 108

Dump truck (Moxy MT36) 112 (SEL basis)

We have also considered noise from miscellaneous sources such as staff vehicle

movements. These noise sources do not contribute to the overall noise levels and we will

therefore not discuss them further.

5.0 PREDICTED NOISE LEVELS

The challenge in predicting noise levels from a mining operation such as this is that the

activity typically occurs in a very small area of the site at any one time. Hence, noise levels at

neighbouring properties will vary significantly, depending on the separation distance at the

time. To address this, we have modelled a number of scenarios:

• Scenario 1 – Operational area adjacent Blue Spur Road (‘Mine Site 2’)

• Scenario 2a – Operational area 100m from south boundary without additional earth

bunds

• Scenario 2b – Operational area 25m from south boundary with additional 3m high earth

bunds

• Scenario 3 – Operational area in southwest corner of site (worst case scenario for

Dwelling A).

Our predicted noise levels for the scenarios above are summarised in Table 3. For noise

contour maps of these scenarios, refer to Appendix B.

Table 3: Predicted noise levels

Receiver Predicted noise level (dB LA10) at notional boundary:

Scenario 1 Scenario 2a Scenario 2b Scenario 3

Dwelling A 47 45 46 52

Dwelling B 45 40 40 41

Dwelling C 46 40 40 42

Dwelling D 54 35 35 37

Dwelling E 39 33 33 33

Dwelling F 40 33 33 34

Dwelling G 38 35 35 36

Dwelling H 49 48 48 48

Subdivision boundary 50 55 55 55



Our predicted noise levels for the above scenarios show that the District Plan noise rule of

55 dB LA10 can be achieved at all existing dwellings. Further analysis shows that all mining

equipment must maintain a set back distance of no less than 150 metres from dwellings D

and E in order to ensure that compliance is achieved at these dwellings at all times. The

construction of earth bunds around mining equipment operating near these dwellings

locations would not significantly reduce the set back distances required from these

dwellings. This is due to the topography in these areas which limit the effectiveness of any

noise barriers.

We have also predicted noise levels at the boundary of the subdivision to the south of the

mine site. Our calculations show that mining activities can achieve the District Plan noise

limit of 55 dB LA10 at the subdivision boundary, provided that a set back distance of 25 m is

maintained from the boundary of the mine site, and earth bunds no less than 3 metres high

are constructed along the mine site boundary as indicated with a blue line on the noise

contour map for Scenario 2b (Appendix B). Alternatively, compliance with the District Plan

noise rules would be achieved without the need for additional earth bunds if a set back

distance of no less than 100 metres from the southern mine site boundary is maintained.

6.0 ASSESSMENT OF NOISE EFFECTS

6.1 Existing Dwellings

Noise emissions from the proposed extension of Little Paddock gold mine will comply with

the District Plan rule of 55 dB LA10 at all times at all existing dwellings, provided that a set

back distance of 150 metres is maintained from Dwellings D and E (refer to Figure 1).

As previously stated, noise levels received at dwellings will vary significantly depending on

the location of the mine at the time. The separation distances between the proposed mining

sites and the existing dwellings in the area are such that noise levels received at most

dwellings will be well below the District Plan noise limit most of the time.

We therefore consider the potential noise effects that may arise at existing dwellings to be

acceptable.

6.2 Subdivision South of Mine Site

We support the option of changing in mining sequence as it would allow the area nearest

the subdivision to be mined first. This may result in mining activity being completed in this

area prior to any houses being occupied in the subdivision.

Our analysis shows that compliance with the District Plan noise rules can be achieved at the

subdivision to the south of the mine site with appropriate noise mitigation measures.

Furthermore, potential subdivision residents will be aware of the noise generation from

existing mining activities that can be expected moving into the area.

We therefore anticipate that any noise effects that may arise at any future dwellings will be

acceptable.



7.0 RECOMMENDATIONS

Based on our analysis, we make the following recommendations to ensure that the activity

complies with the District Plan noise rules at all times:

• Mining activity on site shall only be undertaken between 0700-2100 hours, Monday to

Friday, and 0700-1800 hours on Saturdays;

• All mining equipment must maintain a set back distance of no less than 150 metres from

the nearest façade of dwellings labeled ‘D’ and ‘E’ in Figure 1;

• In the event that a dwelling is constructed on the subdivision to the south of the mine

site, one of the following noise mitigation measures must be implemented:

1) All mining equipment must maintain a set back distance of at least 100 metres

from the southern boundary of the mine site; or

2) All mining equipment must maintain a set back distance of at least 25 metres

from the southern boundary of the mine site, and earth bunds no less than 3

metres high must be constructed along the mine site boundary as indicated with

a blue line on the noise contour map for Scenario 2b (Appendix B).

• Mining operations shall utilise the best practicable option to minimise noise at all times.

This includes regular maintenance and replacement of worn parts, maintenance of

mufflers, lubrication of all moving parts to avoid squeaks and squeals, and appropriate

operation of all equipment.

8.0 CONCLUSIONS

Marshall Day Acoustics has assessed the potential noise effects from the proposed

extension to the Little Paddock gold mining operation in Blue Spur, near Hokitika. The

extension involves utilising additional plant and equipment and the option of changing the

order in which the mine sites will be mined.

Noise levels at existing dwellings and the subdivision to the south of the site have been

predicted for a number of scenarios. The results of these predictions and our subsequent

analysis shows that compliance with the District Plan noise rules can be achieved at all

surrounding noise sensitive receivers with appropriate noise mitigation measures. These

measures include maintaining set back distances from dwellings and constructing additional

earth bunds.

Given that the activity will comply with the District Plan noise rules at all times, and that

noise levels will in fact be significantly lower the District Plan limits at the majority of

dwellings in the area, we anticipate that any noise effects that may arise from the proposal

will be acceptable.



APPENDIX A GLOSSARY OF TERMINOLOGY

SPL or LP Sound Pressure Level

A logarithmic ratio of a sound pressure measured at distance, relative to the

threshold of hearing (20 µPa RMS) and expressed in decibels.

SWL or LW Sound Power Level

A logarithmic ratio of the acoustic power output of a source relative to 10-12

watts and expressed in decibels. Sound power level is calculated from

measured sound pressure levels and represents the level of total sound

power radiated by a sound source.

dB Decibel

The unit of sound level.

Expressed as a logarithmic ratio of sound pressure P relative to a reference

pressure of Pr=20 µPa i.e. dB = 20 x log(P/Pr)

A-weighting The process by which noise levels are corrected to account for the non-linear

frequency response of the human ear.

LAeq (t) The equivalent continuous (time-averaged) A-weighted sound level. This is

commonly referred to as the average noise level. The suffix "t" represents the

time period to which the noise level relates

LA10 (t) The A-weighted noise level equalled or exceeded for 10% of the

measurement period. This is commonly referred to as the average maximum

noise level. The suffix "t" represents the time period to which the noise level

relates.

LAFmax The maximum A-weighted noise level measured using fast response (hence

‘F’), during a chosen sample period.

SEL or LAE Sound Exposure Level

The sound level of one second duration which has the same amount of

energy as the actual noise event measured.

Usually used to measure the sound energy of a particular event, such as a

train pass-by or an aircraft flyover

Noise A sound that is unwanted by, or distracting to, the receiver.

NZS 6802:2008 New Zealand Standard NZS 6802:2008 “Acoustics – Environmental Noise”



APPENDIX B NOISE CONTOUR MAPS

(Provided on following pages)



B1 Scenario 1



B2 Scenario 2a



B3 Scenario 2b



B4 Scenario 3

Little Paddock Gold Mine Extension

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