ROBERTS BANK TERMINAL 2 TECHNICAL DATA REPORT · ROBERTS BANK TERMINAL 2 . TECHNICAL DATA REPORT ....

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From: Panel RBT2 / Commission RBT2 (CEAA/ACEE)To: Panel RBT2 / Commission RBT2 (CEAA/ACEE)Subject: Technical Data Report - Effects of Meteorological Conditions on Sound Propagation from Roberts Bank TerminalsDate: June 27, 2017 2:24:59 PMAttachments: Technical Data Report - Effects of Meteorological Conditions on Sound Propagation from Roberts Bank

Terminals.pdf

Dear Panel Members,

As requested, please find attached the Upland Noise and Vibration Technical Data Report entitled

“Effects of Meteorological Conditions on Sound Propagation from Roberts Bank Terminals” as

referenced in Table 9.3-1 of the Environmental Impact Statement. The document will be posted to the

Registry shortly.

Review Panel Secretariat, Roberts Bank Terminal 2 Project | Secrétariat de la commission

d'examen, Projet du Terminal 2 à Roberts Bank

c/o Canadian Environmental Assessment Agency | a/s de l’Agence canadienne d'évaluation

environnementale

22nd Floor, 160 Elgin St. Ottawa ON K1A 0H3 | 160, rue Elgin, 22ième étage, Ottawa ON K1A 0H3

Panel.RBT2@ceaa.gc.ca / Commission.RBT2@acee.gc.ca

Tel: 613-957-0626 / toll free 1-866-582-1884 | Tél. : 613-957-0626 / sans frais: 1-866-582-1884

mailto:/O=EC/OU=NCR/CN=RECIPIENTS/CN=PANELRBT2_COMMISSIONmailto:PanelRBT2.CommissionRBT2@ceaa-acee.gc.camailto:Panel.RBT2@ceaa.gc.camailto:Commission.RBT2@acee.gc.ca

ROBERTS BANK TERMINAL 2

TECHNICAL DATA REPORT

Upland Noise and Vibration

Effects of Meteorological Conditions

on Sound Propagation from Roberts Bank Terminals Prepared for: Port Metro Vancouver 100 The Pointe, 999 Canada Place Vancouver, BC V6C 3T4 Prepared by: Wakefield Acoustics Ltd. 310-2250 Oak bay Avenue Victoria, BC V8R 1G5 File: 302-042.02 March 2014

Port Metro Vancouver Wakefield Acoustics Ltd. RBT2 – Effects of Meteorology on Sound Propagation March 2014

Technical Report/Technical Data Report Disclaimer

The Canadian Environmental Assessment Agency determined the scope of the proposed Roberts Bank

Terminal 2 Project (RBT2 or the Project) and the scope of the assessment in the Final Environmental

Impact Statement Guidelines (EISG) issued January 7, 2014. The scope of the Project includes the

project components and physical activities to be considered in the environmental assessment. The scope

of the assessment includes the factors to be considered and the scope of those factors. The

Environmental Impact Statement (EIS) has been prepared in accordance with the scope of the Project

and the scope of the assessment specified in the EISG. For each component of the natural or human

environment considered in the EIS, the geographic scope of the assessment depends on the extent of

potential effects.

At the time supporting technical studies were initiated in 2011, with the objective of ensuring adequate

information would be available to inform the environmental assessment of the Project, neither the scope

of the Project nor the scope of the assessment had been determined.

Therefore, the scope of supporting studies may include physical activities that are not included in the

scope of the Project as determined by the Agency. Similarly, the scope of supporting studies may also

include spatial areas that are not expected to be affected by the Project.

This out-of-scope information is included in the Technical Report (TR)/Technical Data Report (TDR) for

each study, but may not be considered in the assessment of potential effects of the Project unless

relevant for understanding the context of those effects or to assessing potential cumulative effects.

https://www.ceaa-acee.gc.ca/050/documents/p80054/97463E.pdf

https://www.ceaa-acee.gc.ca/050/documents/p80054/97463E.pdf

Port Metro Vancouver Wakefield Acoustics Ltd. RBT2 – Effects of Meteorology on Sound Propagation - i - March 2014

EXECUTIVE SUMMARY

This Technical Data Report describes the outcomes of an investigation into the effects of meteorological

conditions on the propagation of sound from the existing Roberts Bank terminals. The investigation

included a review of the current knowledge of long range sound propagation, particularly over water, and

employed that knowledge to illustrate the potential effects of variations in meteorological conditions on the

levels of Port-related noise reaching the adjacent residential areas to the east, along the Tsawwassen

Bluffs and on Tsawwassen First Nation land. The investigation also included the use of commercial sound

propagation software to model the effects of variations in key meteorological conditions on these

noise levels.

Distances from the eastern edge of the Deltaport Terminal to the shoreline are in the range of 3.5 to

4.5 km. Over such distances, atmospheric absorption removes virtually all higher-frequency sound energy

so that the noise reaching distant receivers has only middle and low-frequency content, regardless of air

temperature and humidity. Lower to mid-frequency noise levels in the closest residential areas are

determined in part by the noise levels being emitted by Port operations, and in part by weather conditions,

namely wind direction, wind speed gradients and air temperature gradients.

Results of the literature review indicate that sound travelling long distances over open water may undergo

modest (2 to 3 decibel (dB)) amplification effects, compared to noise levels experienced under neutral

atmospheric conditions, when the wind blows in the direction of sound travel (downwind propagation), or

when positive air temperature gradients (temperature inversions) are present. Sound levels at distant

receivers may be subjected to reductions of up to 10 to 20 dB when the wind blows against the direction

of sound travel, or when strong negative air temperature gradients (temperature lapses) exist, thereby

placing the receivers in a “sound shadow”. Finally, under certain wind conditions, referred to as low level

jets, is it possible for substantial (10 to 15 dB) amplification of sound to occur at large distances from a

water-based noise source, due to the confinement of sound waves within a relatively narrow “channel” or

layer above the water surface.

The effects of upwind and downwind sound propagation in the context of the Roberts Bank terminals

were modelled using three different meteorological algorithms within the CadnaA sound propagation

software. This exercise yielded overall variations in received noise levels between nominal worst-case

and best-case propagation conditions of between 8.7 and 11.7 dB.

Multi-day noise level histories recorded at two locations on the Tsawwassen Bluffs by Wakefield

Acoustics Ltd. (WAL) in June and July of 2013, and at one location by BKL Consultants Ltd. in July and

August of 2011, were reviewed and compared with wind direction and other meteorological data collected

in the local area. The primary findings were that, while the background noise levels from Roberts Bank

terminals operations at residences near the shoreline can show hour by hour variations of 5 to 10 dB,

Port Metro Vancouver Wakefield Acoustics Ltd. RBT2 – Effects of Meteorology on Sound Propagation - ii - March 2014

the daily average levels are quite consistent day to day. More importantly, there is very little clear

correlation between background or average noise levels and either wind direction or the CONCAWE

atmospheric stability class utilised by BKL as an indicator of anticipated sound propagation efficiency.

The clearest evidence of such correlation was found in noise data collected between June 4 and 6, 2013,

at Fred Gingell Park. In this case 12 hours of continuous southeast winds (which would tend to support a

sound shadow) were followed by 25 hours of northwest winds (under which any sound shadow would be

expected to disappear and perhaps be replaced by modest sound amplification). The difference in

average background noise levels measured over these two extended time periods, however, was only

3.3 A-weighted decibels (dBA), appearing to indicate that a sound shadow had not existed during upwind

propagation.

This investigation has then revealed apparent meteorological effects on the Roberts Bank terminals

sound levels experienced at the residential communities to the east which, at 3.3 dBA, were not of

sufficient magnitude to be readily perceptible from one hour, or one day, to the next. The ability to

uncover such effects, however, is confounded to some degree by the fact that Port-related noise

emissions are themselves not entirely constant, so that additional sources of variability may mask the

effects of meteorology on observed sound levels. In addition, and particularly during the daytime, other

non-Port-related noise sources in the community can influence the average noise levels measured. Any

correlation between Port-related noise and meteorological conditions will then be most easily identifiable

during the nighttime hours. Finally, residences located at greater distances (400 to 600 m or more inland)

from the Tsawwassen shoreline may experience larger variations in noise levels from sources at the

Roberts Bank terminals (although likely at lower absolute noise levels), due to the effects of the

intervening land forms on sound propagation.

Port Metro Vancouver Wakefield Acoustics Ltd. RBT2 – Effects of Meteorology on Sound Propagation - iii - March 2014

TABLE OF CONTENTS

EXECUTIVE SUMMARY ............................................................................................................................... I

1.0 INTRODUCTION .............................................................................................................................. 1

1.1 PROJECT BACKGROUND ........................................................................................................ 1

1.2 EFFECTS OF METEOROLOGY ON SOUND PROPAGATION - OVERVIEW ....................................... 1

2.0 REVIEW OF EXISTING LITERATURE AND DATA ....................................................................... 3

2.1 OUTDOOR SOUND PROPAGATION ........................................................................................... 3

2.1.1 Overview ................................................................................................................ 3

2.1.2 Geometric Spreading ............................................................................................. 3

2.1.3 Atmospheric Absorption ......................................................................................... 4

2.1.4 Upward Refraction – Sound Shadows ................................................................... 4

2.1.5 Downward Refraction – Sound Amplification ......................................................... 5

2.1.6 Ground Effect Attenuation ...................................................................................... 6

2.2 LONG RANGE SOUND PROPAGATION OVER WATER ................................................................ 7

2.2.1 Overview ................................................................................................................ 7

2.2.2 Low Level Jets ....................................................................................................... 7

3.0 METHODS ..................................................................................................................................... 10

3.1 STUDY AREA ....................................................................................................................... 10

3.2 TEMPORAL SCOPE............................................................................................................... 10

3.3 STUDY METHODS ................................................................................................................ 10

3.4 DATA ANALYSIS ................................................................................................................... 10

4.0 RESULTS ...................................................................................................................................... 11

4.1 METEOROLOGICAL CONDITIONS IN THE STUDY AREA – OVERVIEW ......................................... 11

4.1.1 Prevailing Winds .................................................................................................. 11

4.1.2 Temperature Inversions Over Water.................................................................... 11

4.1.3 Occurrence of Low Level Jets .............................................................................. 12

4.2 WIND CONDITIONS DURING SPECIFIC PERIODS OF BASELINE NOISE MONITORING .................. 12

4.2.1 WAL Baseline Noise Monitoring of July 22 to 24, 2013 ....................................... 12

4.2.2 WAL Noise Monitoring of June 4 to 6, 2013 ........................................................ 13

4.3 MODELLING THE EFFECTS OF METEOROLOGY ON SOUND PROPAGATION ............................... 13

4.3.1 CadnaA Sound Propagation Software ................................................................. 13

4.3.2 Approaches to Modelling Meterological Effects ................................................... 13

Port Metro Vancouver Wakefield Acoustics Ltd. RBT2 – Effects of Meteorology on Sound Propagation - iv - March 2014

4.3.3 Modelling the Roberts Bank Study Area .............................................................. 14

4.4 OBSERVED EFFECTS OF METEOROLOGICAL CONDITIONS ON COMMUNITY NOISE EXPOSURES 14

4.4.1 Fred Gingell Park, June 4 to 6, 2013 ................................................................... 14

4.4.2 1043 Pacific Drive, July 22 to 24, 2013 ............................................................... 15

4.4.3 476 Tsawwassen Beach Road, July 28 to August 11, 2011 ............................... 15

5.0 DISCUSSION ................................................................................................................................. 17

5.1 KEY FINDINGS ..................................................................................................................... 17

5.1.1 Potential Effects of Meteorology on Sound Propagation ..................................... 17

5.1.2 Observed Effects of Meteorology on Noise Levels at Tsawwassen Residences 18

5.2 DATA GAPS AND LIMITATIONS .............................................................................................. 18

6.0 CLOSURE ...................................................................................................................................... 20

7.0 REFERENCES ............................................................................................................................... 21

8.0 STATEMENT OF LIMITATIONS ................................................................................................... 22

List of Tables

Table 1-1 Effects of Meteorology on Sound Propagation Study Components and Objectives .......... 2

List of Appendices

Appendix A Figures

Appendix B Tables

Port Metro Vancouver Wakefield Acoustics Ltd. RBT2 – Effects of Meteorology on Sound Propagation - 1 - March 2014

1.0 INTRODUCTION

1.1 PROJECT BACKGROUND

The Roberts Bank Terminal 2 Project (RBT2) is a proposed new three-berth marine terminal at Roberts

Bank in Delta, B.C. that could provide 2.4 million TEUs (twenty-foot equivalent unit containers) of

additional container capacity annually. The project is part of Port Metro Vancouver’s Container Capacity

Improvement Program, a long-term strategy to deliver projects to meet anticipated growth in demand for

container capacity to 2030.

Port Metro Vancouver (PMV) has retained Hemmera to undertake environmental studies related to the

Project. This Technical Data Report (TDR) has been prepared by Wakefield Acoustics Ltd. (WAL), in its

role as a sub-consultant to Hemmera. This TDR describes the results of an investigation into the effects

of meteorological conditions on the long-range propagation of sound (noise) from the existing Roberts

Bank terminals to the neighbouring residential communities located on the Tsawwassen Bluffs to the

southeast and Tsawwassen First Nation land to the east of the terminals.

1.2 EFFECTS OF METEOROLOGY ON SOUND PROPAGATION - OVERVIEW

Due to the highly acoustically-reflective nature of water surfaces, sound waves can generally propagate

more efficiently, with less loss of intensity with distance, over bodies of water than over most land

surfaces. Residents of the Tsawwassen Bluffs and Tsawwassen First Nation land are located

approximately 4 to 6 km from the existing Roberts Bank terminals. Despite these relatively large

propagation distances, some residents report being disturbed by noises created by Port-related sources

such as: ship engines; ship generators; train locomotives and other diesel-powered equipment; and

various materials handling activities (bumps and bangs) at the terminals (Municipality of Delta 2012, Port

Metro Vancouver 2012). Residents have also reported experiencing substantial variations in the levels of

terminal-related noise that reach their residences. Some of these reports have come from residents living

near sea level along Tsawwassen Beach Road and on Tsawwassen First Nation land, while others have

come from residents located well above sea level on the bluffs overlooking the BC Ferries and Roberts

Bank terminals. Residents living as far as 800 m from the bluffs have reported being disturbed by such

noises (particularly intermittent/impulsive noises) (Economic Planning Group 2013).

Noise monitoring has been conducted within the residential areas around Roberts Bank on several

occasions (BKL Consultants Ltd. 2004, 2012) over the past decade in relation to former and planned

future expansions to the Roberts Bank terminals. The most extensive of these monitoring programs in

terms of duration was conducted by BKL Consultants Ltd. in July and August of 2011. This program

included two weeks of continuous noise monitoring at three community locations conducted in relation to

the Deltaport Terminal Road and Rail Improvement Project. (one at the Tsawwassen Bluffs, one at the

Tsawwassen First Nation longhouse and one near the Roberts Bank Rail Corridor). However, since none


of the past noise monitoring programs have been truly “long-term” in that they have not extended over an

entire year or even an entire month, it is possible that noise monitoring programs may not yet have

included periods when meteorological conditions were conducive to the exposure of adjacent

communities to Port-related noise at, or near, its highest levels. To address this potential monitoring gap,

the current study has explored the effects of variations in meteorological conditions on sound propagation

from the existing Roberts Bank terminals to the Tsawwassen Bluffs and Tsawwassen First Nation land.

The proposed scope of work for the Uplands Noise and Vibration Impact Assessment component of the

RBT2 environmental studies included a field measurement-based evaluation of the effects of

meteorological conditions on sound propagation in the study area. However, there was concern about the

ability to access the terminal on an ongoing basis in order to create an intense, highly-reproducible sound

that would permit the controlled assessment of sound level variations within the community under a range

of meteorological conditions. There was also concern regarding the likelihood of a suitably wide range of

weather conditions being experienced during the monitoring period. Meteorological effects have

therefore been investigated through application of current theoretical understanding of long-range sound

propagation over water as well as through computer modeling. Table 1-1 below lists the main

components of this study, describes their objectives and provides brief overviews of each.

Table 1-1 Effects of Meteorology on Sound Propagation Study Components and Objectives

Component Objective Overview

Review of existing literature

Determine extent of existing scientific knowledge of long range sound propagation over water.

Review literature regarding long-range sound propagation, in particular the effects of meteorology on sound propagation over water.

Scale of meteorological effects

Establish potential scale of meteorological effects from current theoretical knowledge.

Basic principles of sound attenuation with distance, as well as more unique phenomena that can occur near ocean shores, were employed to establish scale of meteorological effects.

Establish potential scale of meteorological effects using commercial sound propagation software.

Commercial sound propagation modelling and plotting software (CadnaA, Version 4.4, by DataKustiks), was used in conjunction with outdoor sound propagation algorithms contained in ISO 9613-2 (6) to explore variations in community noise levels under various weather conditions.

Examine historical baseline noise and weather data

Establish correlation between weather conditions and Port-related noise levels.

Examine baseline noise monitoring data collected in the study area since 2011 and corresponding weather data to determine to what extent community noise exposures appear to correlate with wind direction and speed records.

Study limitations List factors which may limit the accuracy of study findings.

Factors, other than weather, which may contribute to noise level variability in the neighbouring communities, are discussed.


2.0 REVIEW OF EXISTING LITERATURE AND DATA

2.1 OUTDOOR SOUND PROPAGATION

2.1.1 Overview

There are four principal phenomena that influence the rate of attenuation of sound levels with increasing

distance from the sound source, and ultimately the level (or intensity) of sound reaching receptor points a

substantial distance (here 4 to 6 km) away (Embleton 1996, Crocker 1998). These are:

Geometric spreading.

Atmospheric absorption.

Refraction effects due to wind and air temperature gradients.

Interactions with the surface of the ground (ground effect) or of water.

These effects will be briefly described below.

2.1.2 Geometric Spreading

Geometric spreading refers to the steady expansion of the total area of a sound wave front over which its

energy is distributed as the wave propagates farther and farther from its source (like the dimming of light

as one moves away from a lamp, or the expanding wavelets on a pond when a stone is tossed in). As the

area of the wave front expands, the intensity of the sound diminishes proportionately. For a small,

localised noise source (such as a gun muzzle or a truck or locomotive exhaust), wave fronts spread

outwards in the form of spheres with ever-increasing radii (or hemispheres, in the common case where

the sound source is located close to the ground surface). Since the surface area of a sphere is given by

4π r2, (where r is the radius of the sphere), the rate of sound attenuation with each doubling of distance

(DD) from such a point source is given by:

Spherical Spreading attenuation rate = 10 log [4π (2r)2/4π r

2] = 10 log [4 r

2/ r

2] = 10 log (4) = 6 dB/DD.

Similarly, with a “line” source of sound (like a busy highway, or very long train), wave fronts spread

outwards in the form of cylinders of ever increasing radii. Since the area of a cylinder is given by 2π r L,

where r is the radius and L the length of the cylinder, the rate of sound level attenuation with each

doubling of distance from a line source of sound is given by:

Cylindrical Spreading attenuation rate = 10 log (2π x 2r L / 2π r L) = 10 log (2) = 3 dB/DD.

Therefore, for the noise sources that will be considered in the analysis of sound propagation from the

existing Roberts Bank terminals and from the proposed RBT2, the rate of sound attenuation with distance

due to geometric spreading alone will generally be between 3 and 6 dB per doubling of distance.


2.1.3 Atmospheric Absorption

As sound waves pass through the atmosphere, energy is steadily extracted from the waves by various

processes. Sound waves (which manifest themselves locally as oscillations in the relatively static air

molecules) cause molecules of oxygen and nitrogen, as well as water vapour, to vibrate and rotate –

effects which are referred to collectively as molecular relaxation. The viscosity of the air also consumes

sound wave energy. The rate of atmospheric absorption varies substantially with the frequency of sound

(being much larger at high frequencies than at low and middle frequencies) and also depends on air

temperature, pressure and relative humidity. Global average values for atmospheric absorption

(International Standards Organization (ISO). 1996. Standard 9613-2) range from 0.11 decibels per

kilometer (dB/km) at 63 Hertz (Hz.), to 0.4 dB/km at 125 Hz., to 2.4 dB/km at 500 Hz., to 18.8 dB/km

at 2,000 Hz., and to 129 dB/km at 8,000 Hz. After a sound wave has travelled a long distance, very little

mid to high frequency sound energy remains. Therefore, most Port-related sound heard at residences

4 to 6 km away from the Roberts Bank terminals will be in the low to mid-frequency range.

While atmospheric attenuation rates clearly vary with meteorological conditions, these variations are

much smaller for low-frequency sound. The primary focus of this investigation, therefore, is not on the

effects of variations in atmospheric absorption rates, but rather on the potentially much larger effects of

air temperature and wind gradients on sound propagation, as will be discussed in the next sections.

2.1.4 Upward Refraction – Sound Shadows

Refraction in the noise context refers to the bending of sound waves due to the presence of sound speed

gradients in the atmosphere near the ground. Such sound speed gradients are in turn caused by

gradients in air temperature and/or wind speed with elevation above the ground or water surface. Since

the speed of sound (which is 343 m/sec in dry air at 20 degrees Celsius) increases as air temperature

increases, sound (which, in this context, can be considered to behave like a ray) rarely travels in a

perfectly straight line.

Under calm daytime conditions, when the earth’s surface is warmed by the sun, the air is warmer nearer

the ground than at higher elevations. Under such “temperature lapse” conditions, the speed of sound is

greater near the ground than above it and, as a result, sound waves are refracted, or bent, upwards and

away from the ground. Under temperature lapse conditions, a “sound shadow” zone may develop, into

which relatively little acoustic energy can enter. Sound shadow zones due to temperature lapses can

develop beyond a certain distance from, and in all directions from, the noise source. Such conditions can

then lead to significantly reduced sound levels at large distances from the source, compared to “neutral”

atmospheric conditions (i.e., with little or no wind speed or air temperature gradients) under which sound

waves would follow a more or less straight path.


Sound shadows can also occur when the wind is blowing in the direction opposite to that in which sound

is propagating (i.e., winds from the noise receiver location towards the source location) so that the speed

of sound relative to the earth is higher near the ground than above it, causing sound waves to be

refracted upwards. In this case however, a sound shadow will be experienced only by receivers located

upwind of the sound source. At receiver locations downwind of the source, sound levels will either be

similar to, or higher than, those experienced under neutral conditions. The formation of a sound shadow

due to wind and temperature gradients is illustrated in Appendix A: Figure 1.

Refraction-created sound shadows as described above can theoretically produce excess attenuations of

up to 30 to 40 dB compared to sound levels that would be experienced under neutral atmospheric

conditions. However, other effects, such as atmospheric turbulence and diffraction (which scatter sound

into the shadow zone) and surface, or creeping waves, which are coupled to, and can propagate along

the surface of soft ground and into the shadow zone, impose a practical limit of 15 to 20 dB on such

effects (NPL U.K. 2007).

2.1.5 Downward Refraction – Sound Amplification

There are two mechanisms by which the downwardly-refracted sound waves associated with positive

(increasing with height) wind speed gradients or air temperature gradients (i.e., temperature inversions)

can result in amplified sound levels at large distances. These are discussed in this section and in

Section 2.2.2. The first and more familiar mechanism involves sound waves being bent downwards to the

earth’s surface and then, upon reflection, bent downwards again so that they eventually combine with the

direct but also downward bending wave. Because these direct and reflected sound waves (it is helpful to

think of them as “sound rays” in this situation) follow quite different paths in arriving at the receiver

position, their phases are sufficiently randomised by atmospheric turbulence that they combine

energetically. According to ray theory (Johansson 2003), at most four such reflected rays are possible

between any unique source and receiver locations. Therefore, compared to the neutral atmosphere

situation where a maximum of two sound paths are possible (one direct and one reflected), the maximum

amplification of sound levels that can occur under such downward refraction conditions is given by –

10 log (4 paths/2 paths) = 10 log (2) = 3 dB.

This upper value can only be approached when the intervening surface is hard ground, water or ice. Such

amplification effects under soft ground conditions are smaller as energy is lost from the sound waves

when they encounter such surfaces.

When a wind speed gradient is the cause of such downward bending of sound waves, the zone of sound

amplification occurs only in the downwind direction from the source. However, if the downward bending

is caused by an air temperature inversion, then the sound amplification occurs in all directions around

the source.


2.1.6 Ground Effect Attenuation

If sound is considered to behave as “rays” spreading out uniformly in all directions from a source, then it

can be imagined that under neutral atmospheric condition, there will be one sound ray that travels

directly, in a straight line, from this source to a receiver located some distance away and a modest

distance above the intervening ground. There will be another ray, emitted at an angle slightly below the

horizontal, that will encounter the ground at a point roughly midway between source and receiver and

be reflected upwards so as to arrive at the receiver point very slightly after the direct ray (Appendix A:

Figure 2). This small time delay is a result of the slightly greater path length that the reflected ray follows.

If the intervening ground is hard and acoustically reflective, such as concrete, hard-packed earth, ice or

water, then the reflected sound will arrive at the receiver having suffered little or no loss of energy, and

only a minor phase shift. Therefore, in the hard ground case, the direct and reflected waves combine

constructively, producing a small (less than 3 dB) increase in sound level at the receiver, compared to the

level that would be experienced if the source and receiver were both located far above ground and no

significant reflected sound wave existed. Machinery is commonly operated on acoustically reflective

surfaces; therefore, ground-reflected sound energy is often included in the reference noise emissions for

such equipment.

When the intervening ground between source and receiver is “acoustically soft”, such as lawns,

grassland, farmlands, forests and snow, the reflected sound will be partially absorbed and significantly

phase-delayed, so that when the direct and reflected waves combine at the receiver, they do so

destructively. That is, when the acoustic pressures associated with the two waves arrive at the receiver,

they are largely “out-of-phase” (i.e., one is positive – an “over-pressure”, while the other is negative – an

“under-pressure” or rarefaction) and, as a result, largely cancel one another at the receiver location. The

sound energy is not actually dissipated (destroyed) in this process, but it is locally cancelled, much in the

manner that sound cancellation headphones and other active noise control technologies create local

zones of quiet by generating “out-of phase” sound waves to cancel the sound waves generated by the

actual noise source. In outdoor sound propagation, this sound wave cancellation phenomenon is known

as “ground effect”. This effect is frequency dependent, with the sound frequencies experiencing the

largest cancellation depending on the specific nature (acoustic impedance) of the soft ground surface

involved. Ground effect tends to be largest in the low-mid (200 to 1,000 Hz.) frequency range within which

it can range from 10 to 20 dB, or more. The magnitude of the ground effect increases as the elevations of

the sound source and/or receiver relative to the ground decrease.

Under high tide conditions, the intervening surface between the Roberts Bank terminals and the

residential areas along the shoreline to the east is water, and therefore acoustically hard. During an ebb

tide, it is expected that the sediment surface across the tidal flat would still be relatively hard acoustically,

particularly in areas where the sediments remain saturated very near the sediment-air interface.


Ground effect tends to occur most prominently under neutral, calm wind conditions when both direct and

reflected sound waves follow paths close to the ground, and hence travel through similar portions of the

atmosphere so that introduced phase differences due to atmospheric turbulence are minimized. Ground

effect can be essentially lost under downwind sound propagation or temperature inversion conditions,

both of which create downward bending sound waves due to their positive (increasing with height) wind

speed or temperature gradients. Under such conditions, sound waves tend to follow downward arching

paths relatively high above the earth in reaching distant receivers, thereby largely avoiding the

cancelation effects experienced by waves traveling close to soft ground. The existence of ground effect,

and its loss under the above conditions, together with upwind sound shadow effects, are largely

responsible for the variations experienced in noise levels received from distant noise sources over soft

ground. However, since ground effect does not occur over highly sound-reflective surfaces like water, it is

not expected to influence the reported variations in Roberts Bank terminals activity noise levels, as

received at residences near the waterfront within Tsawwassen.

2.2 LONG RANGE SOUND PROPAGATION OVER WATER

2.2.1 Overview

In the past decade, considerable investigation has been conducted into long-range sound propagation

over water, primarily in relation to the exposure of coastal communities to the noise of offshore wind

turbine farms (Johansson 2003, Boue 2007, Bolin 2009). This research has been directed at developing

best practices for monitoring noise from such wind farms and accurate models for predicting the noise

levels to be expected at distant receivers under various meteorological conditions. All of the sound

attenuation and amplification phenomena described in Section 2.1, with the important exception of

ground effect, can be experienced during the propagation of sound over open water. However, there is an

additional phenomenon, referred to as a Low Level Jet, that has been identified and discussed as part of

these wind farm noise studies which, to some degree, is unique to coastal regions and hence relevant

both to noise from offshore wind farms and marine terminals such as those at Roberts Bank. Low Level

Jets are described in Section 2.2.2.

2.2.2 Low Level Jets

Low level jets (Johansson 2003, Boue 2007, Bolin 2009) are strong winds blowing at relatively low

altitudes, and are typically observed over large flat areas such as oceans, seas and deserts. They can

arise under at least two conditions, known as ‘internal oscillations’ and ‘land sea breezes’.


Low level jets may arise in conjunction with inertial oscillations, which occur when warm inland air flows

out over a cold water surface. Because of the inherent atmospheric stability that develops when a cold

layer of air near the water surface is overtopped by a warmer layer (here encroaching from the land),

there is little or no thermal mixing so that turbulence tends to die away in the layer of air nearest the

water. Without turbulence, shear stress between layers of air near the surface approaches zero and wind

speed is able to increase dramatically with height. Appendix A: Figure 4 shows an example of the type

of vertical wind profiles that can exist under such conditions. It is seen that wind speed increases

rapidly with height until, at about 200 m above the water, it begins to decrease again over approximately

the next 800 m.

The second possible cause of low level jets are the more familiar land-sea breezes. During the daytime,

the sun warms the land and the warmer, lighter air near the land begins to rise. As the warm air over the

land rises and spills out over the adjacent ocean, cooler air from near the ocean surface begins to flow

inland to replace the rising warm air, giving rise to a ‘sea-breeze’. During the nighttime the reverse can

occur - air over the land cools and sinks and flows out over the sea surface giving rise to a ’land breeze‘,

while at higher altitudes, warmer air flows in from the sea and over the land. A sea breeze-related wind

speed profile is shown in Appendix A: Figure 5.

Wind speed profiles associated with low level jets, (as seen in Appendix A: Figures 4 and 5), have the

following effects on sound propagation:

Near the ocean surface, wind speed increases rapidly with height so that sound waves travelling

in the downwind direction are refracted strongly downwards towards the ocean surface.

Above a certain elevation the wind gradient reverses, so that wind speeds begin to decrease with

increasing height and sound waves begin to be refracted upwards away from the ocean.

The effect of such a bifurcated wind speed profile is to create an acoustic “shadow zone” well

above the earth in the downwind direction and, at lower elevations, to constrain the expanding

sound waves to an atmospheric layer of limited height. As a result, beyond a certain distance

from the source, these constrained sound waves begin to experience geometric spreading that is

more cylindrical in nature than spherical.

The key effect of low level jets is that they reduce the rate of attenuation of sound levels with distance

from the source. The distance beyond which the expanding sound wave front begins to look more like a

section of cylinder, or annulus, than a sphere depends upon local weather conditions and the strength of

the low level jet, but it has variously been indicated as being from 200 to 700 m (Boue 2007). Beyond this

distance, the nominal sound attenuation rate due to geometric spreading alone will decrease from 6 to

3 dB/DD. The following expression (Johansson 2003) can be used to estimate the total decrease in

sound levels (at any distance beyond the spherical/cylindrical spreading transition) due to geometric

spreading under low level jet conditions.


Lp = Lw – 20 log (r) – 8 - ∆La - 10 log (r/rtrans) dB.

Where: r = source receiver distance (m);

Lp = sound pressure level at distance r;

Lw = sound power level of source;

8 dB is a constant = 10 log 2π;

∆La = attenuation over distance r due to atmospheric absorption; and

rtrans = distance from source to point of transition from spherical to cylindrical spreading.

It may then be seen that if r is 4,000 m and rtrans is taken as 700 m, the sound level under such a low level

jet condition may be estimated as:

Lp = Lw – 20 log (4000) – 8 - ∆La - 10 log (4000/700) dB

= Lw – 72 – 8 - ∆La – 7.5 dB

= Lw – ∆La – 87.5 dB

In order to estimate the effect of such a low level jet on sound levels at a receiver 4 km away, we may

then calculate the sound level that would exist at the same distance r, in the absence of a low level jet.

Lp = Lw – 20 log (4000) – 8 - ∆La

= Lw – 72 – 8 – ∆La dB

= Lw – ∆La – 80 dB

Under the above conditions, the low level jet effect is then predicted to be 87.5 – 80 = 7.5 dB. If by

comparison, rtrans is taken to be 200 m and the source receiver distance is 5 km, then the low level jet

effect would theoretically be much larger, more specifically 10 log (5,000/200) = 14 dB.


3.0 METHODS

3.1 STUDY AREA

The area encompassed by this investigation into long range sound propagation from the Roberts Bank

terminals includes the terminals themselves, the intervening ocean and the lands surfaces within Delta

and the Tsawwassen Bluffs to the northeast, east and southeast of the terminal that are within a radius of

approximate 6 km from the centre of the terminal. (See Appendix A: Figure 9).

3.2 TEMPORAL SCOPE

The analyses provided herein apply to current conditions at Roberts Bank terminals with regard to Port-

related noise transmission. Since the overall objective is to provide a strong theoretical and pragmatic

understanding of the influence of meteorological conditions on especially landward noise propagation, the

interpretations and conclusions are expected to be applicable into the foreseeable future.

This investigation does not consider possible changes in climatic conditions and the associated

meteorological influences on noise propagation between the present and future (e.g. 2030).

3.3 STUDY METHODS

The study methods involved the completion of the following tasks:

Review literature regarding long range, outdoor sound propagation, particularly over water.

Apply knowledge acquired from literature review to estimate the potential magnitude of

meteorological effect on sound propagation within the study area.

Analyse meteorological data collected at two weather stations in the study area to determine

prevailing wind patterns in relation to Roberts Bank terminals and the communities to the east.

Utilise commercial sound propagation software (CadnaA by DataKustiks) to model the range of

sound levels to be expected in residential communities under various meteorological conditions,

as forecast using three different meteorological effects algorithms.

Review noise level histories recorded in the study area since 2011 to reveal degree of correlation

between wind conditions and noise exposures in the Tsawwassen Bluffs area.

3.4 DATA ANALYSIS

Data analysis for this study was limited to the generation of statistical distributions of wind directions

versus time as collected at the Westshore meteorological station located at the west end of the BC

Ferries terminal and at the Sand Heads Light House, located at the mouth of the South Arm of the Fraser

River. Wind data were scrutinised for the periods during which WAL conducted baseline noise monitoring

in June and July, 2013. These data were visually examined in conjunction with the noise level histories to

determine whether or not there is a correlation between wind conditions and background or average

noise levels at receiver/monitoring sites in the Tsawwassen Bluffs.


4.0 RESULTS

4.1 METEOROLOGICAL CONDITIONS IN THE STUDY AREA – OVERVIEW

4.1.1 Prevailing Winds

Appendix A: Figure 6 shows wind roses generated from wind direction and speed data collected

throughout 2010 at the meteorological station located near Berth 5 at the west end on BC Ferries

terminal. The prevailing winds were from the southeast and east-southeast, with opposing winds blowing

somewhat less frequently from the northwest and west-northwest. These are the assumed typical

prevailing winds direction for locations along the shores of Georgia Strait (Salish Sea), where winds most

commonly blow up and down the straight. The most southerly Portions of the Tsawwassen Bluffs area

(approaching the U.S. border) are frequently either directly upwind of, or downwind from, the existing

Roberts Bank terminals.

Residences at the northern end of the Tsawwassen Bluffs (near the BC Ferries causeway) are located

roughly 45º offset from the prevailing wind direction, and their locations are only infrequently in a direct

upwind or downwind direction from the Roberts Bank terminals. Tsawwassen First Nation residences

(which are largely east-northeast of the terminals), are roughly 90º off the prevailing wind direction and so

are frequently in a crosswind direction with respect to the terminals. Also note from Appendix A:

Figure 6 that the observed “Frequency of Calms” during 2010 was very low (1.3%).

Based on the 2010 wind rose, terminal noise as perceived by residents of the mid and southern portions

of Tsawwassen Bluffs may be subject to some degree of sound shadow attenuation approximately 40%

of the time. Sound from the Roberts Bank terminals must then travel against the prevailing southeasterly

winds to reach these areas. Conversely, for about 20% of the time, sound from the terminals must travel

downwind in reaching the Tsawwassen Bluffs, so that modest amplification of terminal noise (compared

to the levels observed under neutral atmospheric conditions) may occur. On this basis, substantial

variation in Roberts Bank terminals noise levels reaching Tsawwassen Bluffs under upwind (SE) and

downwind (NW) conditions could be expected (with an upper limit of 15 to 20 dBA), depending largely on

the strengths of the sound shadows that are generated to the southeast of the terminals.

4.1.2 Temperature Inversions Over Water

Data showing the prevalence of air temperature inversions over the ocean around the Roberts Bank

terminals were not available. For most of the year, however, the ocean water would be colder than the air

above, so that during periods of little or no wind, a stable temperature inversion could be created in the

layer of air adjacent to the water surface. Such an inversion would then have the effect of amplifying

terminal noise levels by up to 3 dB in all directions from the source and beyond a distance of several

hundred meters.


4.1.3 Occurrence of Low Level Jets

As discussed in Section 2.2.2, low level jets (associated with either sea breezes or inertial oscillations

leading to strong positive wind speed gradients near the surface of open water) can increase the noise

levels from sources well out to sea as perceived by receivers on the shoreline. It is not known

whether such wind conditions actually develop in the study area. The following lines of evidence are

relevant, however:

Should sea breezes develop along the shores of Tsawwassen during the warmer months, they

would blow more or less directly onshore and could then result in enhanced propagation of

terminal noise towards both the Tsawwassen Bluffs and Tsawwassen First Nation land. Based on

the 2010 wind rose shown in Appendix A: Figure 6, winds blew from directions which could be

considered “onshore” (i.e., WNW, W, WSW and SW) for a total of 19% of the time. However,

without a detailed analysis of wind patterns hour by hour and the associated wind speed profiles,

it is not known whether these winds were truly sea-breezes or simply westerly winds. In either

case, some increase in terminal noise levels, compared to those occurring under neutral

conditions, would be expected at residences near the shoreline under these conditions.

Low levels jets associated with inertial oscillations could conceivably occur in the study area, with

warm air from the flat lands of Delta to north of the Tsawwassen Bluffs flowing out over the much

cooler ocean water. However, if a low level jet was to be created in this way, it would tend to blow

from the noise receiver areas on land towards the noise source areas offshore. As a result,

it would be expected to contribute to the formation of a sound shadow at receivers on

Tsawwassen First Nation land rather than noise amplification due to a transition from spherical to

cylindrical wave spreading.

4.2 WIND CONDITIONS DURING SPECIFIC PERIODS OF BASELINE NOISE MONITORING

4.2.1 WAL Baseline Noise Monitoring of July 22 to 24, 2013

In July of 2013 WAL conducted baseline noise monitoring at several locations in the Tsawwassen Bluffs

and on Tsawwassen First Nation land. During the 48-hour monitoring period from July 22 to 24 2013,

five ships came and went from Deltaport. One of these, the Hanover Express, was reported by residents

to be particularly noisy. This was the reason for monitoring on these dates. Meteorological data collected

at the Canadian Government’s Sand Heads Light House (located off the mouth of the Fraser River’s

south arm, approximately 6 km north of Deltaport) were used to establish the wind direction distributions

that existed during this specific noise monitoring period. The wind direction distribution for the 48-hour

period from 11:00 AM July 22 to 11:00 AM, July 24, 2013 over which WAL conducted baseline noise

monitoring is shown in Appendix A: Figure 7. During approximately 29 of the 48 hours (60% of the time),

winds were generally from the southeast and there were no hours during which the prevailing wind

direction was from the northwest. Such a wind distribution would then be expected to have supported the

creation of an acoustic shadow zone in the Tsawwassen Bluffs area.


For a total of seven of these 48 hours (15% of time), winds blew from the SSW and south. During these

hours, sound travelling from the terminals to Tsawwassen Bluffs could be considered to be in a crosswind

situation, during which terminal noise would not be expected to have been either amplified or diminished

due to wind effects. Finally, for five hours (10% of time) the prevailing winds were from the WSW so that

terminal noise could be considered to be traveling downwind towards receivers on Tsawwassen First

Nation land and, as such, could be subject to a minor amplification effect.

4.2.2 WAL Noise Monitoring of June 4 to 6, 2013

In June 2013, WAL conducted continuous noise monitoring over 48-hour periods at four locations in

adjacent communities (three of which are shown in Appendix A; Figure 9) to assist Port Metro

Vancouver in identifying optimal locations for permanent noise monitoring stations in the vicinity of the

Roberts Bank terminals. From approximately 11:00 AM, June 4 to 11:00 AM, June 6, 2013, wind direction

data collected at the Sand Heads Light House (Appendix A: Figure 8) showed that for 28 of the

48 hours (56% of the time), winds blew generally from the northwest (placing the Tsawwassen Bluffs in a

downwind condition associated with a minor sound amplification), while for 8 of the 48 hours (17% of the

time) they blew generally from the southeast (upwind conditions potentially associated with sound

shadow formation). This wind distribution was essentially the opposite of that which was observed during

the baseline noise monitoring of July 22 to 24, 2013.

4.3 MODELLING THE EFFECTS OF METEOROLOGY ON SOUND PROPAGATION

4.3.1 CadnaA Sound Propagation Software

Sound propagation over long distances can be predicted using specialised modelling and contour plotting

software such as CadnaA. Within CadnaA, sound propagation effects are modelled using ISO 9613-2.

This software allows the inputting of various sound source characteristics, source and receiver locations,

intervening terrain characteristics and meteorological conditions in order to generate sound level contours

over the desired study area.

4.3.2 Approaches to Modelling Meterological Effects

In utilising ISO 9613-2 within CadnaA, users may select between three different approaches that have

been developed to account for the effects of meteorological conditions on outdoor sound propagation.

The first two, namely LfU Bayer and LUA NRW, are European algorithms which account only for the

effects of wind direction and hence may be applied to sound propagation over water or land. The third,

approach, CONCAWE, accounts for vector wind speed as well as the stability of the atmosphere in the

local area. Atmospheric stability itself depends on wind speed as well as cloud cover conditions. The

CONCAWE system utilises three atmospheric Pasquill Stability Categories (Unstable, Normal and Stable)

in combination with six vector wind speed ranges to define six Meteorological Categories. Category 1 is

the least favourable to sound propagation (i.e., lowest noise levels at distant receivers), Category 4 is


neutral, having no effects on propagation, and Category 6 is most favourable to propagation (i.e., highest

noise levels at distant receivers). However, because the CONCAWE approach is based on empirical

sound propagation data collected exclusively over land, and because the Pasquill Stability Catagories

were similarly developed in relation to ground, not water, surfaces, the CONCAWE approach has not

been applied here.

4.3.3 Modelling the Roberts Bank Study Area

A CadnaA model of the study area was developed and all three of the above meteorological effects

approaches have been examined. In each case, the CadnaA model was calibrated so as to generate the

same representative level of Roberts Bank terminals noise, specifically L90 42.8 dBA, at the same

receiver location, 1043 Pacific Drive (see site plan in Appendix A: Figure 9). This noise level is

representative of background levels observed during nighttime hours in the Tsawwassen Bluffs due to

ongoing terminal operations and was generated using average meteorological conditions as defined by

the 2010 wind rose (Appendix A: Figure 6). Parameter values corresponding to “most-favourable” and

“least-favourable” propagation conditions were then inputted into the model for each of the three

meteorological effect approaches.

The results of this exercise are summarised in Appendix B: Table 1. The total variation in Roberts Bank

terminals background sound levels at the Tsawwassen Bluffs between most favourable and least

favourable sound propagation conditions, as computed using the LfU Bayer and LUA NRW

meteorological effects approaches, ranged from 8.7 dBA for the LUA NRW approach to 9.8 dBA for the

LfU Bayer approach.

4.4 OBSERVED EFFECTS OF METEOROLOGICAL CONDITIONS ON COMMUNITY NOISE EXPOSURES

4.4.1 Fred Gingell Park, June 4 to 6, 2013

Based on the variations in wind conditions observed during the June 4 to 6, 2013 baseline monitoring

period described in Section 4.2.2, it might be expected that the background noise levels generated at the

Tsawwassen Bluffs by ongoing Roberts Bank terminals operations would exhibit pronounced variations

correlated with the observed variations in wind direction. Some evidence of this is provided by the noise

level histories recorded from June 4 to 6 at Fred Gingell Park. Fred Gingell Park (Appendix A: Figure 9)

is located just west of English Bluff Road between 2nd

and 3rd

Avenues and lies along an east-by-

southeast bearing from the Roberts Bank terminals. The noise level histories recorded at Fred Gingell

Park from 11:00 AM, June 4 to 11:00 AM, June 6 are shown in Appendix A: Figures 10 and 11.

The background noise levels, as represented by the L90, (i.e., that sound level which, during the

monitoring period of interest, was exceeded for 90% of the time) measured from June 4 to 6 do show

some correlation with the wind patterns recorded at Sand Heads during that period. More specifically,

during the 12 hours between 9:00 PM on June 4 and 9:00 AM on June 5, winds blew generally from the


southeast. The average background noise level at Fred Gingell Park during these, largely nighttime,

hours was L90 38.4 dBA. At about 10:00 AM on June 5, the winds reversed and then blew consistently

from the northwest for the next 25 hours, ending at 1:00 PM on June 6. The average background noise

level over this 25 hour period was L90 41.7 dBA. Assuming that the background noise levels at Fred

Gingell Park were controlled by Roberts Bank terminals operations and that the noise emissions from

these operations were essentially constant, then the average effect of the reversal of prevailing winds

(i.e., first upwind and then downwind sound propagation) on Port-related noise levels over these periods

was 3.3 dBA.

4.4.2 1043 Pacific Drive, July 22 to 24, 2013

Sand Heads Light House wind records for July 22 to 24, 2013 may be compared with noise level histories

(Appendix A: Figures 12 and 13) measured over this period at 1043 Pacific Drive located on the

Tsawwassen Bluffs almost due east of the Roberts Bank terminals. With the exception of two brief

periods around 2:00 PM on July 22 and 1:00 AM on July 24, background noise levels (L90’s) were quite

steady. This is expected since, in reaching this monitoring location, terminal noise must travel in a

direction roughly perpendicular to the prevailing winds, so that neither upward nor downward sound

refraction will tend to occur with any regularity. However for a few brief periods (9:00 PM on July 22,

8:00 PM on July 23, and 8:00 AM on July 24), the wind blew from the east, while for approximately one

hour around 4 PM on July 23, it blew from the west. Therefore during the former three periods, the

1043 Pacific Drive monitoring site was directly upwind of the terminals, while during the later single

period, it was directly downwind. However, from Appendix A: Figures 12 and 13, it is seen that

background noise levels (L90’s) during the corresponding hours reveal no co-variation with these periods

of easterly and westerly winds.

4.4.3 476 Tsawwassen Beach Road, July 28 to August 11, 2011

The two noise monitoring sites discussed in Section 4.6 and 4.7 were both located on the top of the

Tsawwassen Bluffs, 45 to 55 m above sea level. It is possible that upwind sound shadow effects and

downwind sound amplification effects were not clearly evident at these locations because, given their

elevations above the ocean and the Port-related noise sources, wind gradient-related sound refraction

effects were not fully developed. It is therefore of interest to examine the noise level histories collected by

BKL Consultants Ltd. (BKL 2012) in relation to the Deltaport Terminal Road and Rail Improvement Project

(DTRRIP) which included a site much closer to sea level. BKL collected noise level histories at three

locations over a two week period from July 28 to August 12, 2011. BKL’s Site 1 was located on the roof of

the residence at 476 Tsawwassen Beach Road and, as such, was 5 to 10 m above sea level. Based on

data collected with a portable weather station located 3.5 m above ground, the CONCAWE

Meteorological Categories that existed throughout the noise monitoring period were calculated and

plotted alongside the noise level histories obtained.


Overall, there was no consistent correlation between average noise levels and CONCAWE

Meteorological Categories. In fact, the recurring pattern was for the lowest average noise levels (typically

around 40 dBA) to occur during the nighttime hours (generally between 10:00 PM and 5:00 AM) when

Meteorological Category 5 (moderately favourable sound propagation conditions) prevailed. There was

some evidence that noise levels increased during the few brief periods when Category 6 (most favourable

sound propagation conditions) occurred. In the first instance, Category 6 occurred over three midday

hours on August 1. Average noise levels were 48 to 54 dBA during this period; however, they continued

in this elevated range for several more afternoon and evening hours during which Categories 3, 4 and 5

were prevalent. Another hour of Category 6 conditions occurred at midday on August 6, during which

average noise levels were in the 49 to 53 dBA range. However, noise levels were also in this range

during the previous hour when Category 3 prevailed.


5.0 DISCUSSION

The following sections present the key findings of this investigation into the effects of meteorology on the

propagation of sound from the Roberts Bank terminals to adjacent residential areas and also discuss the

data gaps and limitations of the study.

5.1 KEY FINDINGS

Based on the well-established principals of outdoor sound propagation over land and on more recently

acquired understanding of unique sound propagation phenomena that can occur along coastlines, it might

be expected that pronounced variations in Roberts Bank terminals noise levels would be observed at

residential locations along Tsawwassen shoreline to the east of the terminals. However, based on the

review of noise histories and corresponding local wind logs, only modest (3 to 4 dBA) variations in

average background noise levels were observed and even these were not consistent over time

and space.

5.1.1 Potential Effects of Meteorology on Sound Propagation

The meteorological conditions that would be expected to most influence the levels of Port-related noise

received at the Tsawwassen Bluffs and on the adjacent Tsawwassen First Nation land are wind direction

and speed and/or air temperature gradients in the atmospheric layer directly above the intervening ocean

surface.

On the infrequent occasions that neither wind speed nor air temperature gradients exist above the ocean

surface, “neutral” atmospheric conditions are considered to exist, and sound levels at distant residences

are neither amplified nor attenuated due to the refraction, or “bending” of sound waves downwards

towards or upwards away from the surface. Under such conditions, the levels of Port-related noise

reaching residences 4 to 6 km away depend predominantly upon Port emission levels and source-

receiver distance (spherical spreading of sound waves with increasing distance).

When either a wind speed or temperature gradient exists in the atmospheric layer near the ocean

surface, then current understanding suggests that Roberts Bank terminals noise levels at the residential

shoreline may be somewhat higher (up to 3 dB) or substantially lower (10 to 20 dB) than the noise levels

experienced under neutral atmospheric conditions. The direction and magnitude of these effects will

depend on wind direction and the strength of wind and/or temperature gradients.

Amplification of Port-related noise levels at shoreline residences by more than a few decibels above their

neutral atmosphere values appears only to be possible in the presence of a “low level jet”, which through

its associated strong downward refraction of sound waves near the ocean surface and upward refraction

of sound at greater elevations, can “trap” sound waves near the water, thereby reducing the rate at which

sound is attenuated with distance due to geometrical spreading and potentially increasing noise levels by

as much as 10 to 15 dBA. While it is possible that low level jets leading to sound amplification (most likely

daytime sea-breezes) could occur along the Tsawwassen shoreline, evidence of this is not available.


The effects of upwind and downwind sound propagation in the context of the Roberts Bank terminals

were modelled using three different meteorological algorithms within the CadnaA sound propagation

software. This exercise yielded overall variations in received noise levels between nominal worst-case

and best-case propagation conditions of between 8.7 and 11.7 dB.

5.1.2 Observed Effects of Meteorology on Noise Levels at Tsawwassen Residences

Review of local wind logs from 2010 and 2013 has shown that prevailing wind directions in the study area

are from the southeast and northwest (up and down the Georgia Straight) so that residences along the

Tsawwassen Bluffs (particularly the southern portion) are, for much of the time, either upwind or

downwind of the Roberts Bank terminals.

Comparison of local weather station wind logs with the noise level histories obtained through continuous

noise monitoring conducted by WAL in June and July, 2013, and by BKL Consultants Ltd. in July and

August, 2011, has revealed some limited examples of correlation between wind direction and Roberts

Bank terminals noise levels. However, this correlation has been neither strong nor consistent.

The clearest evidence of such correlation was seen in noise data collected between June 4 and 6, 2013

at Fred Gingell Park overlooking Tsawwassen beach. In this instance 12 hours of continuous southeast

winds were followed by 25 hours of northwest winds. The difference between the average background

noise levels measured over these two extended time periods was 3.3 dBA. A noise level variation of this

magnitude is consistent with the minor sound amplification associated with downwind sound propagation

or a temperature inversion over water, but not with the loss of a fully-developed sound shadow that might

be expected to accompany a reversal in wind direction from southeast to northwest. Changes in noise

levels of this magnitude (3.3 dBA) are not readily perceptible if they occur from one hour, or one day,

to the next.

5.2 DATA GAPS AND LIMITATIONS

The following sections present issues and factors which may limit the accuracy and/or general

applicability of the results and observations made in the above sections.

Due to the variety of noise sources (fixed and mobile equipment, ships, etc.) active at the Roberts Bank

terminal (including BC Ferries) at any given time, the levels of quasi-continuous noise (as opposed to

intermittent, often impulsive, noises from material handling activities) emitted from the terminals tend to be

fairly steady over time. However, they are not entirely steady, so that any variations in the collective

noise emissions from these terminals (hour to hour, daytime to nighttime, etc.) may confound and

obscure background noise level(s) variations observed at the residences that might be attributable to

meteorological effects.


Particularly during the daytime, other noise sources not related to Port facilities contribute to the overall

noise environment in the waterfront residential areas, thereby potentially obscuring variations in Port-

related noise levels that may be attributable to meteorological effects.

No prolonged noise monitoring has been done during winter months when meteorological effects on

sound propagation may be different than during summer months.

It is possible that, at residential locations much farther inland than the monitoring sites discussed herein,

the effects of meteorology on the levels of Port-related noise may be more pronounced. In the case of

Tsawwassen First Nation land, it is possible that some ground effect attenuation could occur at locations

far enough from the shoreline to permit sound waves reflected from the soft ground surface to interfere

destructively with sound waves arriving directly from the Roberts Bank terminals. This would, however, be

a sound-reducing, rather than sound-amplifying effect. Sound levels would then “appear” to be amplified

under conditions, such as downwind propagation under westerly winds, which would cause this ground

effect to be partially or entirely lost. It is also possible that, at residences located more than about 400 m

east of the Tsawwassen Bluffs, terrain shielding effects created by the ridge running parallel to, and

inland from, the shoreline may reduce exposures to Port-related noise under most weather conditions. It

is possible that under westerly wind conditions, this terrain shielding could be partially or entirely lost,

resulting in higher Port-related noise levels at these residences. Again this would not truly be a sound

amplification effect, but rather the loss of excess attenuation due to terrain shielding.


6.0 CLOSURE

Major authors and reviewers of this technical data report are listed below, along with their signatures.

Report prepared by: Wakefield Acoustics Ltd.

Clair W. Wakefield, M.A.Sc., P.Eng. President Report peer reviewed by: Wakefield Acoustics Ltd.

Andrew P. Williamson, P.Eng. Project Engineer


7.0 REFERENCES

BKL Consultants Ltd. 2004. Roberts Bank Container Expansion Project Environmental Noise

Assessment. Prepared for Port Metro Vancovuer, Vancouver, B.C,

BKL Consultants Ltd. 2012. Deltaport Terminal Road and Rail Improvement Project Environmental Noise

and Vibration Assessment, Final Draft Report, File No. 2720-11B. Prepared for Port Metro

Vancovuer, Vancouver, B.C.

Bolin, K. 2009. Wind Turbine Noise and Natural Sounds – Masking, Propagation and Modeling.

Boue, M. 2007. Long-Range Sound Propagation Over the Sea with Application to Wind Turbine Noise.

Final Report to the Swedish Energy Agency Project 21597-3.

Crocker, M. J., editor. 1998. Handbook of Acoustics, Chapter 28, Atmospheric Sound Propagation.

Economic Planning Group. 2013. Roberts Bank Terminal 2: Survey of Area Residents Regarding Noise

and Vibration Issues. Prepared for Port Metro Vancovuer, Vancouver, B.C.

Embleton. T. F. 1996. Tutorial on Sound Propagation Outdoors. Journal of Acoustical Society of

America, Volume 100 (1). July, 1996.

International Standards Organization (ISO). 1996. ISO Standard 9613-2, “Acoustics- Attenuation of

sound during propagation outdoors”, Part 2 – General Method of Calculation.

Johansson, L. 2003. Sound Propagation around Off-shore Wind Turbines. Licentiate Thesis,

Department of Civil and Architectural Engineering, Div. of Building Technology, Stockholm,

Sweden.

Municipality of Delta. 2012. Community Complaints Log.

National Physical Laboratory (NPL), U.K. 2007. Guide to Predictive Modelling of Environmental

Noise, Appendix A – Sound Propagation theory and Methodologies. Acoustics Group, National

Measurement Systems Acoustics Programme, 2004 – 2007.

Port Metro Vancouver. December 2012. Complaints Log (January 1 to December 6, 2012).

Sondergaard, B. and B. Plovsing. 2005. Noise from Offshore Wind Turbines. Danish Ministry of

the Environment, Environmental Protection Branch, Environmental Project No. 1016.


8.0 STATEMENT OF LIMITATIONS

This report was prepared by Wakefield Acoustics Ltd., based on research and fieldwork conducted by

Wakefield Acoustic Ltd., for the sole benefit and exclusive use of Port Metro Vancouver. The material in it

reflects Wakefield Acoustics Ltd.’s best judgment in light of the information available to it at the time of

preparing this Report. Any use that a third party makes of this Report, or any reliance on or decision

made based on it, is the responsibility of such third parties. Wakefield Acoustics Ltd. accepts no

responsibility for damages, if any, suffered by any third party as a result of decisions made or actions

taken based on this Report.

Wakefield Acoustics Ltd. has performed the work as described above and made the findings and

conclusions set out in this Report in a manner consistent with the level of care and skill normally

exercised by members of the consulting engineering profession practicing under similar conditions at the

time the work was performed.

This Report represents a reasonable review of the information available to Wakefield Acoustics Ltd. within

the established Scope, work schedule and budgetary constraints.

In preparing this Report, Wakefield Acoustics Ltd. has relied in good faith on information provided by

others as noted in this Report, and has assumed that the information provided by those individuals is both

factual and accurate. Wakefield Acoustics Ltd. accepts no responsibility for any deficiency, misstatement

or inaccuracy in this Report resulting from the information provided by those individuals.

APPENDIX A

Figures

Port Metro Vancouver APPENDIX A Wakefield Acoustics Ltd. RBT2 – Effects of Meteorology on Sound Propagation - 1 - March 2014

Figure 1 Illustrations of the Formation of Sound Shadows under Upwind Propagation or Temperature Lapse Conditions

Figure 2 Illustration of the Situation in which Ground Effect Attenuation can Occur due to the Destructive Interference of Direct and Ground-Reflected Sound Waves when both Travel Close to Soft Ground


Figure 3 Illustrations of the Downward Refraction of Sound Waves Downwind Propagation or Temperature Lapse Conditions

Figure 4a Sound Propagation Simulation Result for 80 Hz., Low Level Jet Conditions (12) Left - Wind Speed Profile of Low Level Jet (LLJ) Centre – Relative Sound Level Distribution under LLJ Right – Relative Sound Level Legend/Palette


Figure 4b Wind Speed & Direction Profiles of Low Level Jet caused by Inertial Oscillation (8)

Figure 5 Wind Speed & Direction Profiles Associated with Low Level Jet caused by a Sea Breeze (9)


Figure 6 2010 Wind Rose from Weather Station (located at west end of BC Ferries terminal)


Figure 7 Wind Direction Histogram (Sand Heads) for July 22 to 24, 2013

0

2

4

6

8

10

12

10 30 50 70 90 110 130 150 170 190 210 230 250 270 290 310 330 350

Nu

mb

er

of

Ho

urs

Wind Direction (0/360 = North, 90 = East, 180 = South, 270 = West)


Figure 8 Wind Direction Histogram (Sand Heads) for June 4 to 6, 2013


Figure 9 Noise Monitoring Site Plan. Extent of 6 km (from centre of Deltaport) sound propagation study zone indicated by red line


Figure 10 Noise Level History Measured by WAL June 4 to 5, 2013 at Fred Gingell Park, Tsawwassen

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

11:30 AM 2:00 PM 4:30 PM 7:00 PM 9:30 PM 12:00 AM 2:30 AM 5:00 AM 7:30 AM 10:00 AM

So

un

d P

ressu

re L

evel

(dB

A)

Time

DNMN - Prelim Monitoring Site 4; Fred Gingell Park, Tsawwassen, June 4-5, 2013

noise levels in 15 minute intervals

Leq(15 min) Lmax L90

Ldn = 52.1 dBA


Figure 11 Noise Level History Measured by WAL June 5 to 6, 2013 at Fred Gingell Park, Tsawwassen


Figure 12 Noise Level History Measured by WAL July 22 to 23, 2013 at 1043 Pacific Drive, Tsawwassen

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

10:30 AM 1:00 PM 3:30 PM 6:00 PM 8:30 PM 11:00 PM 1:30 AM 4:00 AM 6:30 AM 9:00 AM

So

un

d P

ressu

re L

evel

(dB

A)

Time

RBT2 - Baseline Noise Monitoring Site 3; 1043 Pacific Drive, Tsawassen, July 22-23, 2013



Ldn = 54.3 dBA


Figure 13 Noise Level History Measured by WAL July 23 to 24, 2013 at 1043 Pacific Drive, Tsawwassen

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

10:45 AM 1:15 PM 3:45 PM 6:15 PM 8:45 PM 11:15 PM 1:45 AM 4:15 AM 6:45 AM 9:15 AM

So

un

d P

ressu

re L

evel

(dB

A)

Time

RBT2 - Baseline Noise Monitoring Site 3; 1043 Pacific Drive, Tsawwassen, July 23-24, 2013



Ldn = 54.1 dBA

APPENDIX B

Tables

Port Metro Vancouver APPENDIX B Wakefield Acoustics Ltd. RBT2 – Effects of Meteorology on Sound Propagation - 1 - March 2014

Table 1 Modelled Variations in Roberts Bank Terminals Sound Levels at Tsawwassen Bluffs (1043 Pacific Drive) due to Variations in Meteorological Conditions (Wind Direction)

Meteorology

Standard

Site 3 – Average Port-related Sound Level

L90 (dBA)

Variation in L90 Relative to Average Conditions (dBA)

Total Variation in

L90 (dBA)

(Upwind vs. Downwind)

Average Wind

Conditions

Downwind

Conditions

Upwind Conditions

Downwind Conditions

Upwind Conditions

FfU Bayerr 45.0 47.6 37.8 2.5 - 7.4 9.8

LUA NRW 45.0 47.6 38.9 2.4 - 6.3 8.7

ROBERTS BANK TERMINAL 2 TECHNICAL DATA REPORT: Upland Noise and Vibration Effects of Meteorological Conditionson Sound Propagation from Roberts Bank Terminals


Executive Summary

Table of Contents

1.0 Introduction

1.1 Project Background

1.2 Effects of Meteorology on Sound Propagation - Overview

2.0 Review of Existing Literature and Data

2.1 Outdoor Sound Propagation

2.1.1 Overview

2.1.2 Geometric Spreading

2.1.3 Atmospheric Absorption

2.1.4 Upward Refraction – Sound Shadows

2.1.5 Downward Refraction – Sound Amplification

2.1.6 Ground Effect Attenuation

2.2 Long Range Sound Propagation Over Water

2.2.1 Overview

2.2.2 Low Level Jets

3.0 Methods

3.1 Study Area

3.2 Temporal Scope

3.3 Study Methods

3.4 Data Analysis

4.0 Results

4.1 Meteorological Conditions in the Study Area – Overview

4.1.1 Prevailing Winds

4.1.2 Temperature Inversions Over Water

4.1.3 Occurrence of Low Level Jets

4.2 Wind Conditions during Specific Periods of Baseline Noise Monitoring

4.2.1 WAL Baseline Noise Monitoring of July 22 to 24, 2013

4.2.2 WAL Noise Monitoring of June 4 to 6, 2013

4.3 Modelling the Effects of Meteorology on Sound Propagation

4.3.1 CadnaA Sound Propagation Software

4.3.2 Approaches to Modelling Meterological Effects

4.3.3 Modelling the Roberts Bank Study Area

4.4 Observed Effects of Meteorological Conditions on Community Noise Exposures

4.4.1 Fred Gingell Park, June 4 to 6, 2013

4.4.2 1043 Pacific Drive, July 22 to 24, 2013

4.4.3 476 Tsawwassen Beach Road, July 28 to August 11, 2011

5.0 Discussion

5.1 Key Findings

5.1.1 Potential Effects of Meteorology on Sound Propagation

5.1.2 Observed Effects of Meteorology on Noise Levels at Tsawwassen Residences

5.2 Data Gaps and Limitations

6.0 Closure

7.0 References

8.0 Statement of Limitations

APPENDICES

APPENDIX A: Figures

APPENDIX B: Tables

ROBERTS BANK TERMINAL 2

TECHNICAL DATA REPORT

Upland Noise and Vibration

Effects of Meteorological Conditions

on Sound Propagation from Roberts Bank Terminals Prepared for: Port Metro Vancouver 100 The Pointe, 999 Canada Place Vancouver, BC V6C 3T4 Prepared by: Wakefield Acoustics Ltd. 310-2250 Oak bay Avenue Victoria, BC V8R 1G5 File: 302-042.02 March 2014

Port Metro Vancouver Wakefield Acoustics Ltd. RBT2 – Effects of Meteorology on Sound Propagation March 2014


The Canadian Environmental Assessment Agency determined the scope of the proposed Roberts Bank

Terminal 2 Project (RBT2 or the Project) and the scope of the assessment in the Final Environmental

Impact Statement Guidelines (EISG) issued January 7, 2014. The scope of the Project includes the

project components and physical activities to be considered in the environmental assessment. The scope

of the assessment includes the factors to be considered and the scope of those factors. The

Environmental Impact Statement (EIS) has been prepared in accordance with the scope of the Project

and the scope of the assessment specified in the EISG. For each component of the natural or human

environment considered in the EIS, the geographic scope of the assessment depends on the extent of

potential effects.

At the time supporting technical studies were initiated in 2011, with the objective of ensuring adequate

information would be available to inform the environmental assessment of the Project, neither the scope

of the Project nor the scope of the assessment had been determined.

Therefore, the scope of supporting studies may include physical activities that are not included in the

scope of the Project as determined by the Agency. Similarly, the scope of supporting studies may also

include spatial areas that are not expected to

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