Harvest Power Canada Ltd. Air Quality Assessment for ...

Submitted by:

Levelton Consultants Ltd.

150 – 12791 Clarke Place

Richmond, BC V6V 2H9

T: 604.278.1411

F: 604.278.1042

[email protected]

Date: October 15th, 2013

Levelton File #: EE12-1250-00

Report By: Kyle Howe, M.Sc. Reviewed by: Chris Koscher, B.Sc.(Hons.), EP

Harvest Power Canada Ltd.

Air Quality Assessment for Harvest Power (Richmond, BC): Cogeneration and Flare

October 15th, 2013

Johanna van den Broeke Officer, Air Quality Permitting Specialist Metro Vancouver

Environmental Regulation & Enforcement Division

4330 Kingsway

Burnaby, BC V5H 4G8

Dear Johanna:

Regarding: Air Quality Assessment for Harvest Power (Richmond, BC): Cogeneration and

Flare

Levelton Consultants Ltd. (Levelton) is pleased to submit the attached revised air quality

assessment report for Harvest Power Canada Ltd.’s facility in Richmond, BC which evaluates

potential ambient air quality impacts from cogeneration and flaring emissions.

Sincerely, Levelton Consultants Ltd.

Per: Chris Koscher, B.Sc.(Hons.), EP Senior Air Quality Specialist 604.207.5133 [email protected]

Attachment: Air Quality Assessment Report

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Air Quality Assessment for Harvest Power (Richmond, BC): Cogeneration and Flare EE12-1250-00

Table of Contents

page

1. INTRODUCTION ............................................................................................... 1

2. AMBIENT AIR QUALITY OBJECTIVES ..................................................................... 1

3. BACKGROUND AMBIENT AIR QUALITY ................................................................... 2

4. SOURCE PARAMETERS ...................................................................................... 5

4.1 Cogeneration ............................................................................................... 5

4.2 Flare ......................................................................................................... 5

5. CALMET AND CALPUFF MODELLING METHODOLOGY ................................................ 7

5.1 Modelling Domain ......................................................................................... 7

5.2 Building Downwash ........................................................................................ 8

5.3 Conversion from NOx to NO2 ............................................................................ 10

6. DISPERSION MODELLING RESULTS ..................................................................... 11

6.1 Cogeneration .............................................................................................. 11

6.2 Flare ........................................................................................................ 14

7. CONCLUSION ................................................................................................ 16

8. REFERENCES ................................................................................................ 16

APPENDIX A: MODELLING METHODOLOGY ................................................................... 17

A-1. LOCAL CLIMATE AND METEOROLOGY ................................................................. 18

A-1.1 Temperature .............................................................................................. 18

A-1.2 Wind ........................................................................................................ 21

A-1.3 Conclusion from Comparison of Meteorological Data to Climate Normals ..................... 24

A-2. MODELLING METHODOLOGY ............................................................................ 24

A-2.1 Model Selection ........................................................................................... 24

A-2.2 CALMET ..................................................................................................... 25

A-2.2.1 CALMET Modelling Domain ........................................................................ 25

A-2.2.2 Terrain Elevation and Land Use Data ........................................................... 27

A-2.2.3 Meteorological Data ................................................................................ 27

A-2.2.4 CALMET Model Options ............................................................................. 28

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A-2.2.5 CALMET Quality Assurance and Control ......................................................... 29

A-2.3 CALPUFF ................................................................................................... 38

A-2.3.1 CALPUFF Model Options ........................................................................... 38

A-2.3.2 Model Domain and Receptors ..................................................................... 38

A-2.3.3 Building Downwash ................................................................................. 41

A-3. REFERENCES ................................................................................................ 41

List of Figures

Figure 3-1 Lower Fraser Valley Air Quality Monitoring Network (2011) and Harvest Power

(shown as a white star) .......................................................................... 3

Figure 5-1 CALMET and CALPUFF Modelling Domains .................................................... 8

Figure 5-2 Facility Buildings and Point Sources........................................................... 9

Figure 5-3 NO2/NOx Ratio versus 1-hour Average NOx Observations from Metro Vancouver

Station T18 (Burnaby South) ................................................................... 10

Figure 6-1 Predicted Maximum 1-hour NO2 (100% conversion) for the CHP ........................ 13

Figure 6-2 Predicted Maximum 1-hour SO2 from the Normal Operations Scenario for the

Flare ............................................................................................... 15

Figure A-1 Temperature Normals for MSC Vancouver International Airport (1971-2000) ........ 19

Figure A-2 2000-2001 Temperature Observations for MSC Vancouver International Airport .... 20

Figure A-3 2000-2001 Temperatures near Harvest Power (Extracted from CALMET

Output) ............................................................................................ 21

Figure A-4 2002-2007 Windrose for MSC Vancouver International Airport .......................... 22

Figure A-5 2000-2001 Wind Rose for MSC Vancouver International Airport ......................... 23

Figure A-6 2000-2001 Wind Rose near the MSC Vancouver International Airport

(Extracted from CALMET Output) ............................................................. 23

Figure A-7 2000-2001 Wind Rose near Harvest Power (Extracted from CALMET Output) ........ 24

Figure A-8 Map Displaying the CALMET and CALPUFF Modelling Domain ............................ 26

Figure A-9 Example Wind Field Generated by CALMET for the 10 m Level for the Hour

Ending at 11:00 on November 10, 2000 ..................................................... 30

Figure A-10 Frequency Distribution of Surface (10 m level) Winds for Surface Stations and

near Harvest Power (CALMET) ................................................................ 31

Figure A-11 Average Monthly Wind Speeds at Surface (10 m level) for Surface Stations and

Harvest Power (CALMET) ....................................................................... 32

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Figure A-12 Diurnal Wind Speed Distribution of Surface (10 m level) Winds for Surface

Stations and Harvest Power (CALMET) ....................................................... 33

Figure A-13 Monthly Temperatures at Surface Stations and Harvest Power (CALMET) ............ 34

Figure A-14 Hourly Temperatures at Surface Stations and the Harvest Power (CALMET) ......... 35

Figure A-15 Frequency Distribution of Stability Classes Calculated for Vancouver Airport

(YVR) and Harvest Power (CALMET) for the Modelling Period ........................... 36

Figure A-16 Hourly Predicted Mixing Heights for Harvest Power (CALMET) .......................... 37

Figure A-17 Receptor Grid for Harvest Power Modelling ................................................ 39

Figure A-18 Layout of Harvest Power with Buildings Used in BPIP Denoted in Blue ................ 40

List of Tables

Table 2-1 Summary of Ambient Air Quality Objectives ................................................ 2

Table 3-1 Maximum 1-hour concentration from ambient monitoring stations (T13, T17,

T18) from 2008 - 2012 ........................................................................... 3

Table 3-2 Maximum 8-hour concentration from ambient monitoring stations (T13, T18)

from 2008 - 2012 ................................................................................. 3

Table 3-3 Maximum 24-hour concentration from ambient monitoring stations (T13, T17,

T18) from 2008 - 2012 ........................................................................... 4

Table 3-4 98th percentile 24-hour concentration from ambient monitoring stations (T13,

T17, T18) from 2008 - 2012 ..................................................................... 4

Table 3-5 Maximum annual average concentration from ambient monitoring stations

(T13, T17, T18) from 2008 - 2012 ............................................................. 4

Table 3-6 Summary of Background Ambient Air Quality Concentrations for Air Quality

Assessment ........................................................................................ 5

Table 4-1 Stack Parameters and Emissions from Cogeneration (CHP) ............................... 5

Table 4-2 Physical Stack Parameters of the Flare ...................................................... 6

Table 4-3 Gas Composition, Effective Stack Parameters and SO2 Emission Rate for Flare ...... 6

Table 5-1 Building dimensions used in BPIP .............................................................. 9

Table 6-1 Predicted Concentrations from the CHP .................................................... 12

Table 6-2 Predicted SO2 Concentrations from the Flare .............................................. 14

Table A-0-1 Heights of CALMET Model Layers ............................................................. 27

Table A-0-2 Surface Meteorological Stations Used for CALMET Input ................................. 28

Table A-0-3 Selected CALMET Wind Field Model Options ................................................ 29

Table A-0-4 Selected Dispersion Options Used in CALPUFF Modelling................................. 38

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© 2013 ALL RIGHTS RESERVED

THIS DOCUMENT IS PROTECTED BY COPYRIGHT LAW AND MAY NOT BE REPRODUCED IN ANY

MANNER, OR FOR ANY PURPOSE, EXCEPT BY WRITTEN PERMISSION OF LEVELTON

CONSULTANTS LTD.

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1. Introduction

Harvest Power Canada Ltd. (Harvest Power) owns and operates a food scrap and yard debris

composting, and cogeneration facility in Richmond, BC (the facility was previously known as Fraser

Richmond Soil and Fibre (FRSF)). The facility is located at 7028 York Road (latitude 49º 9’ 38.20” N,

123 º 2’ 14.36” W; or 497279 m E, 5445311 m N in Universal Transverse Mercator (UTM), grid zone 10

coordinates, NAD83 reference).

Harvest Power holds contracts with a number of municipalities around the Lower Mainland to collect

food scraps and other compostable materials such as yard trimmings. The Harvest Power site consists

of multiple piles of compost at various stages of aging. As the piles reach maturity, they are then

moved to a screening area where they are separated by size and either sold as soil or re-introduced

into the aging piles. In addition to the composting operations, there is a cogeneration power plant

which converts biogas produced by the decay of food waste into electricity.

Harvest Power engaged Levelton Consultants Ltd. (Levelton) to conduct air dispersion modelling to

predict potential air quality impacts from their Harvest’s operations as a requirement of Approval

A1054-2012-01 with Metro Vancouver. This assessment focuses on the air quality impacts from the

cogeneration unit (Combined Heat and Power (CHP)) and the flare. Further air dispersion modelling

and assessment work will be completed in the near term to assess the air quality impacts from the

composting operations on the site.

2. Ambient Air Quality Objectives

The federal and provincial governments, as well as Metro Vancouver, have developed ambient air

quality objectives to promote long-term protection of public health and the environment. Federally,

two objective values have been recommended using the categories "maximum desirable" and "maximum

acceptable". The "maximum desirable” objective is the most stringent federal standard. British

Columbia has established similar sets of objective values, designated as levels A, B and C, with level A

being the most stringent. Level A is typically applied to new and proposed discharges to the

environment, and is usually the same as the federal "maximum desirable" objective. Metro

Vancouver’s ambient air quality objectives are based on current knowledge regarding air quality and

health, and take into consideration relevant objectives from around the world and the ability to

achieve those objectives within the Metro Vancouver region.

Table 2-1 summarizes the ambient air quality objectives for the species modelled in this study.

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Table 2-1 Summary of Ambient Air Quality Objectives

Averaging

Period

British Columbia Objective * Federal Objective ** Metro

Vancouver

Objective

(µg/m3)

Most

Stringent

Objective

(µg/m3)

Level A

(µg/m3)

Level B

(µg/m3)

Level C

(µg/m3)

Maximum

Desirable

(µg/m3)

Maximum

Acceptable

(µg/m3)

Sulphur Dioxide (SO2)

1-hour 450 900 900-1300 450 900 450 450

3-hour 375 665 - - - - 375

24-hour 160 260 360 150 300 125 125

Annual 25 50 80 30 60 30 25

Nitrogen Dioxide (NO2)

1-hour - - - - 400 200 200

Annual - - - 60 100 40 40

Carbon Dioxide (CO)

1-hour 14300 28000 35000 15000 35000 30000 14300

8-hour 5500 11000 14300 6000 15000 10000 5500

Particulate Matter (PM2.5)

24-hour 25 28*** 25**** 25****

Annual 8 10*** 8 8

Particulate Matter (PM10)

24-hour - 50 - - - 50 50

Annual - - - - - 20 20

*Concentrations given at 20ºC, 101.3 kPa, dry basis

**Concentrations given at 25ºC, 101.3 kPa, dry basis

***Canadian Ambient Air Quality Standards

****Based on rolling average

Source: British Columbia Ministry of Environment (http://www.bcairquality.ca/reports/pdfs/aqotable.pdf)

Environment Canada (http://www.ec.gc.ca/rnspa-naps/default.asp?lang=En&n=24441DC4-1)

Metro Vancouver (http://www.metrovancouver.org/about/publications/Publications/AQMPSeptember2005.pdf)

Canadian Ambient Air Quality Standards (http://ec.gc.ca/default.asp?lang=En&n=56D4043B-1&news=A4B2C28A-2DFB-

4BF4-8777-ADF29B4360BD)

3. Background Ambient Air Quality

Metro Vancouver operates an extensive network of ambient air quality and meteorological monitoring

stations (Figure 3-1). Data from three monitoring stations (T13 North Delta, T17 Richmond South and

T18 Burnaby South) were used for characterizing the background air quality in the area surrounding

Harvest Power. The red circles, triangle and squares identify the stations and the white star identifies

the approximate location of Harvest Power’s facility. The monitoring stations were chosen based on

their proximity to Harvest Power and the air quality parameters monitored.

http://www.bcairquality.ca/reports/pdfs/aqotable.pdf

http://www.ec.gc.ca/rnspa-naps/default.asp?lang=En&n=24441DC4-1

http://www.metrovancouver.org/about/publications/Publications/AQMPSeptember2005.pdf

http://ec.gc.ca/default.asp?lang=En&n=56D4043B-1&news=A4B2C28A-2DFB-4BF4-8777-ADF29B4360BD

http://ec.gc.ca/default.asp?lang=En&n=56D4043B-1&news=A4B2C28A-2DFB-4BF4-8777-ADF29B4360BD

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Source: Metro Vancouver, 2013

Figure 3-1 Lower Fraser Valley Air Quality Monitoring Network (2011) and Harvest Power

(shown as a white star)

Five years of recent data (2008-2012) were analysed for each station and are summarized belowError!

eference source not found.. For each station and averaging period, maximum observed

concentrations are presented as well as the 98th percentile 24-hour observed concentrations. The 98th

percentile is the value at or below which 98 percent of the values in the data fall.

Table 3-1 Maximum 1-hour concentration from ambient monitoring stations (T13, T17, T18)

from 2008 - 2012

Ambient Monitoring Station

Maximum 1-hour Concentrations (µg/m3)

SO2 O3 NO2 NO PM10 PM2.5 CO

North Delta (T13) - 148 121 392 - 163 -

Richmond South (T17) 31 144 109 432 97 46 7095

Burnaby South (T18) 53 158 107 328 175 59 2097

Table 3-2 Maximum 8-hour concentration from ambient monitoring stations (T13, T18) from

2008 - 2012

Ambient Monitoring Station

Maximum 1-hour Concentrations (µg/m3)

CO

Richmond South (T17) 1557

Burnaby South (T18) 2783

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Table 3-3 Maximum 24-hour concentration from ambient monitoring stations (T13, T17, T18)

from 2008 - 2012

Ambient Monitoring Station 24-hour Maximum Block Average Concentrations (µg/m3)


North Delta (T13) - 85 76 205 - 24 -

Richmond South (T17) 6 92 72 180 35 16 1580

Burnaby South (T18) 11 86 69 181 46 28 1243

Table 3-4 98th percentile 24-hour concentration from ambient monitoring stations (T13, T17,

T18) from 2008 - 2012

Ambient Monitoring Station 24-hour 98th Percentile Block Average Concentrations (µg/m3)


North Delta (T13) - 70 55 58 - 12 -

Richmond South (T17) 5 74 54 106 24 11 776

Burnaby South (T18) 6 68 55 45 27 11 571

Table 3-5 Maximum annual average concentration from ambient monitoring stations (T13,

T17, T18) from 2008 - 2012

Ambient Monitoring Station Maximum Annual Average Concentrations (µg/m3)


North Delta (T13) - 36 28 14 - - -

Richmond South (T17) 3 37 27 19 - - 322

Burnaby South (T18) 3 36 30 11 13 5 332

Background concentrations were estimated for each pollutant and averaging period by using data from

2008 – 2012. Each station’s background values were averaged together to yield the background values

in Table 3-6. The 24-hour maximum and 98th percentile values were calculated based on blocks from

midnight to midnight. The methodology used to estimate the background concentrations is consistent

with the Guidelines for Air Quality Dispersion Modelling in British Columbia (AQMG) (BC MOE, 2008)

and has been accepted by the BC MOE and Metro Vancouver in other air quality assessments.

The background ambient concentration data collected at the Metro Vancouver stations provide an

indication of the pollutant levels given the current transportation, residential, commercial and

industrial sources in the Metro Vancouver area. The data collected cannot be used to identify specific

facility emissions.

The background ambient air quality concentrations used in the air quality assessment are summarized

in the following table.

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Table 3-6 Summary of Background Ambient Air Quality Concentrations for Air Quality

Assessment

Averaging Period Background Concentration

CO (µg/m3) NO2 (µg/m3) SO2 (µg/m3) PM10 (µg/m3) PM2.5 (µg/m3)

1-hour 4596 112 42 - -

24-hour 2170 (8-hour) - 9 41 23

Annual Average - 29 3 13 5

* “-“ indicates that there is no applicable air quality objective for the averaging period and therefore a background

concentration has not been calculated for the air quality assessment.

4. Source Parameters

This section will summarize the two point sources on the site, the CHP and the flare. The dispersion

modelling results for the composting operations will be provided in a separate report.

4.1 Cogeneration

The cogeneration (Combined Heat and Power (CHP)) engine is used to convert biogas generated from

food waste into electricity. The GE Jenbacher engine is rated for approximately 1 MW of energy

production at full load. The stack height and diameter were provided by Harvest Power and the

remainder of the stack and emissions information was obtained from: manufacturer specifications,

factory test data, and a prior engineering report for the facility (GICON, 2011). The flow rate provided

in the GE Jenbacher technical specifications was corrected from a normalized temperature of 0°C to

stack conditions (509°C). It is anticipated that the engine will run continuously, with the exception of

downtime for maintenance, and will produce electricity at nearly full load. While it is unlikely the CHP

will run at less than full load, lower flow rates were modelled. Table 4-1 summarizes the relevant

stack parameters used in the CALPUFF air dispersion modelling.

Table 4-1 Stack Parameters and Emissions from Cogeneration (CHP)

Emission Source

Stack Height

(m)

Stack Diameter

(m)

Stack Exit Temperature

(K)

Stack Exit

Velocity (m/s)

Emission Rate (g/s)

NOx SOx VOC CO PM10 / PM2.5

CHP – 100% Load 10 0.35 782 37.7 0.634 0.051 0.152 1.267 0.013

CHP – 75% Load 10 0.35 782 28.3 0.634 0.051 0.152 1.267 0.013

CHP – 50% Load 10 0.35 782 18.9 0.634 0.051 0.152 1.267 0.013

CHP – 25% Load 10 0.35 782 9.4 0.634 0.051 0.152 1.267 0.013

4.2 Flare

The Harvest Power facility is equipped with a Varec 244W candle stick flare. In the event of an

emergency or maintenance of the CHP, biogas will need to be flared. It is expected that the flare will

not be used often, and in most cases only for maintenance purposes. Flaring of biogas is meant to

relieve pressure in the system until such time that the food waste digesters stop producing biogas.

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The maximum biogas throughput was given as 265 m3/hr (GICON, 2011) and the raw biogas

concentration will consist of:

60-75% CH4

40-25% CO2

2000 – 3000 ppm (without desulphurization).

Prior to the biogas entering the CHP or flare, it will pass through a desulphurization unit which has a

manufacturer’s guaranteed output value of 100ppm H2S in the biogas. Therefore, for this assessment,

two flaring scenarios have been considered. The first is normal operations where the H2S content of

the gas is 100ppm and the second scenario is an upset condition where the biogas does not pass

through the desulphurization unit and has an H2S concentration of 3000ppm.

Both flaring scenarios presented in the report assumes approximately 75% CH4 and 25% CO2. Other

modelling scenarios were run to determine the sensitivity of the model to the change in gas

concentrations (ie. ~ 60% CH4, 40% CO2) and the results are of the same magnitude.

The physical stack height and diameter were provided by Harvest Power. Effective stack parameters

for the flare were then calculated based on the guidance provided in the AQMG. Furthermore, the

stack’s exit velocity and temperature for modelling were assumed to be 20 m/s and 1273 K respectively

based on the AQMG recommendations.

The physical stack parameters are outlined in Table 4-2 and the input parameters considered in

modelling are shown in Table 4-3.

Table 4-2 Physical Stack Parameters of the Flare

Physical Stack Parameters

Stack Height (m) 4.0

Flow Rate (m3/hr) 265

Flow Rate (MMscf/d) 0.225

Table 4-3 Gas Composition, Effective Stack Parameters and SO2 Emission Rate for Flare

Scenario Gas Composition Effective

Stack Height (m)

Effective Stack

Diameter (m)

Exit Velocity (m/s)*

Exit Temperature

(K)*

SO2 Emission Rate (g/s)

CO2 CH4 H2S

Normal Conditions

25% 74.99% 0.01% 6.29 0.44 20 1273 0.0199

Upset Conditions

25% 74.70% 0.3% 6.29 0.44 20 1273 0.5977

*AQMG recommended value for flare

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5. CALMET and CALPUFF Modelling Methodology

Air dispersion modelling was conducted following the methods recommended by the BC MOE in the

AQMG and with input from Metro Vancouver on the Detailed Model Plan for Harvest Power Richmond

Facility (Levelton, 2013). This section presents a brief summary of the modelling methods. A detailed

description is provided in Appendix A.

The CALPUFF model suite was used for this analysis. CALPUFF is a suite of numerical models (CALMET,

CALPUFF, and CALPOST) that are used in series to determine the impact of emissions in the vicinity of

a source or group of sources. Detailed three-dimensional meteorological fields were produced by the

diagnostic computer model CALMET (v5.8, EPA approved), based on surface and upper air weather

data, digital land use data, terrain data, and prognostic meteorological data. The three-dimensional

fields produced by CALMET were used by CALPUFF (v5.8, EPA approved), a three-dimensional, multi-

species, non-steady-state Gaussian puff dispersion model that can simulate the effects of time and

space varying meteorological conditions on pollutant transport. Finally CALPOST, a statistical

processing program, was used to summarize and tabulate the pollutant concentrations calculated by

CALPUFF.

The three-dimensional CALMET meteorological fields were generated using meteorological data from

numerous surface stations and upper air stations, prognostic meteorological data from the Mesoscale

Compressible Community (MC2) model, and digital terrain and land use data.

5.1 Modelling Domain

The CALMET modelling domain was a 32 km by 32 km domain area centred approximately 2.1 km to the

south southeast of Harvest Power’s facility, with a 250 m grid resolution and nine vertical layers. This

domain was approved as part of the detailed modelling plan submitted to Metro Vancouver. Details of

the CALMET modelling methodology are provided in Appendix A.

The CALPUFF modelling domain was similar to the CALMET modelling domain, but extended to within

1 km of the CALMET boundaries to avoid edge effects. Within the domain, a nested sampling grid of

receptors was created with the following special distributions:

20 m spacing along the facility boundary;

50 m spacing within 500 meters of the centre of the facility;

250 m spacing within 2 km of the centre the facility;

500 m spacing within 5 km of the centre of the facility; and

1000 m spacing to beyond 5 km of the centre of the facility.

In addition to the nested grids described above, Metro Vancouver requested a higher resolution

receptor grid over portions of Metro Vancouver. These areas are considered to be areas with a high

population density and will be used in the odour dispersion modelling to assess the potential for odour

impacts.

Receptors were not included within the plant boundary, where ambient air quality objectives are not

applicable. A 1.5 m receptor height was used to simulate the average height of human air intake.

Figure 5-1 shows the CALMET and CALPUFF domain including the receptors.

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Figure 5-1 CALMET and CALPUFF Modelling Domains

5.2 Building Downwash

The US EPA Building Profile Input Program (BPIP-PRIME) was used to analyze stack and building

dimensions for possible building downwash effects. The results of the BPIP-PRIME model were then

used as input to the CALPUFF model, and turbulent wake effects were simulated. Figure 5-2 shows the

buildings at Harvest Power’s facility used in BPIP-PRIME. Building downwash was applied to both the

flare and the CHP.

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Figure 5-2 Facility Buildings and Point Sources

Table 5-1 shows the dimensions of the buildings used in BPIP.

Table 5-1 Building dimensions used in BPIP

Building Name Width (m) Length (m) Height (m)

HSAD Building – Tier 1 26 54 8.4

HSAD Building – Tier 2 12 13 10.5

Percolators 31 43 5.7

Digesters 12 12 13.5

Tanks 12 12 9.0

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5.3 Conversion from NOx to NO2

The ambient air quality objectives refer to NO2 (not NOx), and the CALPUFF model does not account for

NOx to NO2 conversion. In accordance with the AQMG, if 100% NOx conversion leads to exceedances of

the ambient air quality objectives then the Ambient Ratio (AR) method should be implemented to

convert predicted NOx concentrations into NO2 concentrations. The AR method utilizes representative

hourly NOx and NO2 monitoring data to characterize the NO2:NOx ratio given the ambient NOx

concentration. The method then applies this ratio to the model predicted NOx emissions from the

facility.

Ambient air quality data from Metro Vancouver station T18 (Burnaby South) was used to calculate the

ratio of NO2/NOx. The resulting ratio was validated against NO2/NOx ratios and ambient air quality

from Metro Vancouver stations T13 (North Delta) and T17 (Richmond South). For the 1-hour averaging

period an exponential equation of the form y = axb was fit to the upper envelope of observed NO2/NOx

versus NOx, where a and b are empirically determined constants. The resulting equation was used to

determine the ratio of NO2/NOx subject to the constraints that the equation is only valid for NOx values

where the corresponding NO2/NOx ratio is not less than 0.1, or greater than 1. A conversion of 100% of

NOx to NO2 was applied for NO2/NOx values greater than 1. Figure 5-3 illustrates the dependence of

NO2/NOx ratio on ambient NOx air quality. For the annual averaging period 100% conversion was

considered.

Figure 5-3 NO2/NOx Ratio versus 1-hour Average NOx Observations from Metro Vancouver

Station T18 (Burnaby South)

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6. Dispersion Modelling Results

6.1 Cogeneration

Table 6-1 shows a summary of the predicted maximum concentration from the air dispersion model and

includes the respective background values. All of the modeled species with background fall below the

applicable ambient air quality objectives, with the exception of the 1-hour NOx result assuming 100%

conversion from NOx to NO2 where eight fence line receptors were predicted to exceed the 200 µg/m3

ambient air quality objective when including the 1-hour NO2 background of 112 µg/m3. The BC

Modelling Guidelines stipulate that if under 100% NOx to NO2 conversion leads to an exceedance of an

air quality objective, that the ambient ratio method be applied, as defined in Section 5.3. Applying

the ambient ratio method to calculate the 1-hour NO2 results, all of the predicted concentrations are

below the most stringent ambient air quality objectives.

In addition, if the maximum predicted concentrations below in Table 6-1 are added to the respective

background concentrations summarized in Table 3-6, all values are below the most stringent ambient

air quality objectives.

Levelton also considered three additional scenarios with reduced flows of 25%, 50% and 75% in order to

determine the potential impacts from the CHP unit if it is not run at full load. These three scenarios

used the maximum guaranteed emissions (Section 4.1) and all three scenarios had predicted

concentrations under ambient air quality guidelines. Additionally, Harvest Power has indicated that it

is very unlikely that the CHP unit would be run at less than full load. Therefore, only the 100% load

results are presented below.

Figure 6-1 shows the predicted maximum 1-hour NO2 (100% conversion) concentrations from the CHP.

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Table 6-1 Predicted Concentrations from the CHP

Pollutant

1-hour Average 24-hour Average Annual Average

(µg/m3) (µg/m3) (µg/m3)

Predicted Concentration


Including Background

Air Quality

Objective




Air Quality

Objective




Air Quality

Objective

Maximum Receptor

Maximum Receptor

Maximum Receptor

Maximum Receptor

Maximum Receptor

Maximum Receptor

NOx 164 276 - 45 117 - 4 33 -

NO2* 80 192 200 45 117 - 4 33 40

SO2 13 55 450 4.0 12 125 0.33 3 30

VOC 39 - - 11 - - 1 - -

CO 328 4924 30000 - - - - - -

PM10 3 139 - 1 42 50 0.08 13 20

PM2.5** 3 93 - 1*** 24 25 0.08 5 8

*The NO2 concentrations are based on the ambient ratio method using the maximum predicted NOx value.

**The PM2.5 concentrations assume that PM10 represents PM2.5

***The 24-hour PM2.5 concentrations are based on a rolling 24-hour average

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Contours are 5, 10, 20 and 40 µg/m3.

Figure 6-1 Predicted Maximum 1-hour NO2 (100% conversion) for the CHP

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6.2 Flare

Table 6-2 summarizes the predicted SO2 concentrations for both the normal and upset scenarios for the

flare. Due to the nature of how the flare operates, only the 1-hour and 24-hour averages are

presented below. It is very unlikely that the flare will be operational for a continuous 24-hour period,

so this a conservative estimate of SO2 concentrations. Additionally, it is not expected that the

desulphurization unit will be bypassed and flaring events operate under the normal operation scenario.

Predicted maximum SO2 concentrations are well below all applicable objectives.

In addition, if the maximum predicted concentrations below in Table 6-2 are added to the respective

background concentrations summarized in Table 3-6, all values are below the most stringent ambient

air quality objectives.

Table 6-2 Predicted SO2 Concentrations from the Flare

Scenario

1-hour Average (µg/m3) 24-hour Average (µg/m3)

Predicted SO2 Concentration



Air Quality

Objective (µg/m3)




Air Quality

Objective (µg/m3)

Maximum Receptor

Maximum Receptor

Maximum Receptor

Maximum Receptor

Normal Conditions

55 97 450 16 25 125

Upset Conditions

164 206 450 47 56 125

Figure 6-2 shows the predicted maximum 1-hour SO2 concentrations from the flare.

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Contours are 1, 2, 5, and 10µg/m3

Figure 6-2 Predicted Maximum 1-hour SO2 from the Normal Operations Scenario for the Flare

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7. Conclusion

Levelton Consultants Ltd. (Levelton) was engaged by Harvest Power to conduct air dispersion modelling

in support of their draft permit application for their facility located in Richmond, BC. Harvest Power is

a composting facility which receives organic waste (food scraps and yard debris) from around the Lower

Mainland. This assessment focuses on the air quality impacts from the cogeneration unit (Combined

Heat and Power (CHP)) and flare. Further air dispersion modelling and assessment work will be

completed in the near term to assess the air quality impacts from the composting operations on the

site.

Air dispersion modelling was conducted using the CALPUFF model suite considering a climatologically

representative meteorological data set of just over one year in duration. Stack and emissions for the

cogeneration unit and flare were determined as outlined in Section 4.

Based on the predicted model results, plus calculated background ambient air quality concentrations

for the Criteria Air Contaminants (CACs) considered for this assessment, no ambient air quality

objectives were exceeded from emissions from the cogeneration unit or flare.

8. References

BC Ministry of Environment (Environmental Protection Division, Environmental Quality Branch, Air

Protection Section), 2008. Guidelines for Air Quality Dispersion Modelling in British Columbia

http://www.env.gov.bc.ca/epd/bcairquality/reports/pdfs/air_disp_model_08.pdf

GICON, 2011. FRSF Process Technology Emissions. Prepared by GICON for Harvest Power.

Levelton, 2012. Detailed Model Plan for Harvest Power Richmond Facility. Submitted / approved by

Metro Vancouver January 30th, 2013.

Metro Vancouver, Air Quality Policy and Management Division, 2013. 2011 Lower Fraser Valley Air

Quality Monitoring Report.

http://www.metrovancouver.org/about/publications/Publications/AmbientAirQuality2011.pdf

Scire, Joseph S. et al., 2000a. A User’s Guide for the CALMET Meteorological Model (Version 5). Earth

Tech Inc.

Scire, Joseph S. et al., 2000b. A User’s Guide for the CALPUFF Dispersion Model (Version 5). Earth

Tech Inc.


http://www.metrovancouver.org/about/publications/Publications/AmbientAirQuality2011.pdf

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Appendix A: Modelling Methodology

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A-1. Local Climate and Meteorology

To assess the local climate in the area of Harvest Power, 30-year climate normals were obtained from

the Meteorological Service of Canada (MSC) for Vancouver International Airport (YVR). The

meteorological fields generated by the CALMET model were compared to these climate normals and to

observed YVR meteorological data for the June 13, 2000 – July 7, 2001 modelling period, in order to

determine the suitability of the CALMET data for the dispersion modelling.

A-1.1 Temperature

Ambient temperatures recorded at Vancouver International Airport from 1971 to 2000, and for the

2000-2001 modelling period are shown in Figure A-1and Figure A-2. The temperatures extracted from

the CALMET output near FRFS are shown in Figure A-3. The mean daily temperatures listed in the

figures were calculated by averaging the daily mean temperature over the entire monitoring period for

each month. The mean daily maximum and minimum temperatures were calculated by averaging daily

maximum and minimum temperatures for the month. The extreme maximum and minimum

temperatures are the maximum and minimum temperatures for the monthly period.

The mean, maximum and minimum extracted CALMET temperatures are within the climate normals for

the area as outlined by the data from Vancouver International Airport, and are in good agreement with

the observed temperatures at Vancouver International Airport for the 2000-2001 modelling period.

Thus, the temperature data set employed in this analysis is a good representation of statistically

normal conditions for the airshed.

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Figure A-1 Temperature Normals for MSC Vancouver International Airport (1971-2000)

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Figure A-2 2000-2001 Temperature Observations for MSC Vancouver International Airport

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Figure A-3 2000-2001 Temperatures near Harvest Power (Extracted from CALMET Output)

A-1.2 Wind

Representative wind data are required for dispersion modelling, as model predictions will be

significantly affected if appropriate data are not utilised. As a general rule, dispersion model

predictions of ground level concentration at a given point are determined by wind direction and are

inversely proportional to mean wind speed.

Figure A-4 shows a wind rose for Vancouver International Airport based on data from 2002 to 2007

Figure A-5 and Figure A-6 show wind roses for the 2000-2001 modelling period, based on observed

Vancouver International Airport data and CALMET output extracted near YVR, respectively. Based on

the climate normals shown in Figure A-1 and the observational data shown in Figure A-5, the

predominant winds for the area are from the east. The wind rose extracted from the CALMET output

near FRFS (Figure A-7) shows that the predominant winds at this location are also from the east, as

expected from the climate normals and observational data.

-30.0

-20.0

-10.0

0.0

10.0

20.0

30.0

40.0

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Tem

pe

ratu

re (

C )

Extreme Maximum

Average Daily Maximum

Average Daily

Average Daily Minimum

Extreme Minimum

0 C

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Figure A-4 2002-2007 Windrose for MSC Vancouver International Airport

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Figure A-5 2000-2001 Wind Rose for MSC Vancouver International Airport

Figure A-6 2000-2001 Wind Rose near the MSC Vancouver International Airport (Extracted

from CALMET Output)

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Figure A-7 2000-2001 Wind Rose near Harvest Power (Extracted from CALMET Output)

A-1.3 Conclusion from Comparison of Meteorological Data to Climate Normals

A comparison of the CALMET meteorological fields with the 2000-2001 observations from Vancouver

International Airport and with the 30-year climate normals from Vancouver International Airport shows

that the CALMET data is climatologically representative of the area. Hence modelling using 2000-2001

observations is sufficient to assess the potential impacts of Harvest Power’s emissions on ground level

pollutant concentrations in the area. Utilising more meteorological data or subsequent years of

meteorology would likely not provide greater insight into the maximum predicted pollutant

concentrations and their frequency of occurrence.

A-2. Modelling Methodology

A-2.1 Model Selection

CALPUFF is a suite of numerical models (CALMET, CALPUFF, and CALPOST) that are used in series to

determine the impact of emissions in the vicinity of a source or group of sources. Detailed three-

dimensional meteorological fields are produced by the diagnostic computer model CALMET, based on

surface, marine (optional) and upper air weather data, digital land use data, terrain data, and

prognostic meteorological data (optional). The three-dimensional fields produced by CALMET are used

by CALPUFF, a three-dimensional, multi-species, non-steady-state Gaussian puff dispersion model that

can simulate the effects of time and space varying meteorological conditions on pollutant transport.

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Finally CALPOST, a statistical processing program, is used to summarize and tabulate the pollutant

concentrations calculated by CALPUFF.

A-2.2 CALMET

The CALMET (version 5.8, EPA approved) model was executed to calculate meteorological fields for the

period from June 13, 2000 to July 7, 2001. This modelling period was chosen in order to utilize

available three-dimensional prognostic meteorological data from the Mesoscale Compressible

Community (MC2) model, provided by the University of British Columbia, to improve the performance

of the CALMET model. Meteorological input data was used from 19 surface stations and two upper air

stations. The meteorological data and CALMET output for this modelling period were analysed and

compared with climate normals to ensure that this modelling period is climatologically representative,

as discussed in Section C-1. A description of the CALMET methods and data sets follows. This

methodology presented in this section applies to the original modelling domain. Identical methodology

applies to the larger domain used for NO2 modelling.

A-2.2.1 CALMET Modelling Domain

The Universal Transverse Mercator (UTM, NAD 83) co-ordinate system was used for this model

application. The CALMET domain was a 32 km by 32 km area, as shown in Figure A-8. The extracted

MC2 domain encompassed a slightly larger area around the CALMET domain. Within the CALMET

modelling domain a 250 m grid resolution was used. The CALMET modelling domain and grid resolution

were chosen to encompass the main topographical features for generating the CALMET three-

dimensional diagnostic meteorological fields. On the vertical axis, nine atmospheric layers were

included in order to capture the expected paths of the plumes from the modelled source. The heights

of these layers are given in Table A-0-1.

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Note: Location of Harvest Power is indicated by the orange box.

Figure A-8 Map Displaying the CALMET and CALPUFF Modelling Domain

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Table A-0-1 Heights of CALMET Model Layers

Vertical Layer

Number

Height at Top of Layer

(m)

1 20

2 40

3 80

4 140

5 200

6 500

7 1000

8 2000

9 4000

A-2.2.2 Terrain Elevation and Land Use Data

Digital terrain and land use data covering the model domain was included in the CALMET input data

set. Digital terrain files with a 1:50000 scale were used to generate the CALMET grid cells. Land use

characteristics for each grid cell based on LandData BC data sets were used. The BC land use class

codes were translated into the land use class codes used by CALMET according to the procedures in the

BC Air Quality Modelling Guidelines (AQMG) (BC MOE, 2008).

A-2.2.3 Meteorological Data

Surface meteorological stations that record hourly data include those operated by the Meteorological

Service of Canada (MSC), the BC MOE and Metro Vancouver (previously GVRD). Data from nineteen

surface stations, listed in Table A-0-2, were used as input to the CALMET model. Upper air data from

the vicinity of the area was used from the Port Hardy station, operated by Environment Canada, and

the Quillayute, Washington station, operated by the US National Weather Service.

In its normal mode, CALMET requires a measured data value for every hour from at least one

meteorological station in order to simulate the three-dimensional fields. Missing data procedures were

implemented, when required, as per the AQMG.

As a supplement to the observational data, three-dimensional meteorological fields from the MC2

prognostic model were used (provided by the University of British Columbia). The MC2 prognostic data

was used as input into CALMET as the “initial estimate” field. The "initial estimate" wind field is

calculated by interpolating the winds to the fine CALMET scale and then adjusting them for terrain and

land-use effects. Utilising the MC2 data in this fashion allows for maximum use of actual surface data,

while allowing the MC2 data to replace the surface extrapolated data described in the upper air

section, and thus overall, an improved wind field is generated, both at the surface and aloft.

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Table A-0-2 Surface Meteorological Stations Used for CALMET Input

Surface Meteorological Station Operated By:

T02 Kitsilano - Vancouver Metro Vancouver

T04 Kensington Park - Burnaby Metro Vancouver

T06 Second Narrows - North Vancouver Metro Vancouver

T09 Rocky Point Park - Port Moody Metro Vancouver

T13 North Delta Metro Vancouver

T14 Burnaby Mountain Metro Vancouver

T15 Surrey East Metro Vancouver

T17 Richmond South Metro Vancouver

T18 Burnaby South Metro Vancouver

T20 Pitt Meadows Metro Vancouver

T23 Capitol Hill - Burnaby Metro Vancouver

T24 Burnaby North Metro Vancouver

T26 Mahon Park - North Vancouver Metro Vancouver

T30 Maple Ridge Metro Vancouver

T32 Coquitlam Metro Vancouver

Vancouver Airport MSC

Whistler MSC

Annacis Island BC MOE

Squamish BC MOE

A-2.2.4 CALMET Model Options

The CALMET model has a number of user-specified input switches and options that determine how the

model handles terrain effects, interpolation of observational input data, etc. The differences in the

modelled and measured meteorological fields were examined for a short time frame, and this analysis

was used to determine which model options were appropriate for modelling of impacts over the whole

year.

Table A-0-3 outlines the options that were used that have not been previously described. The current

recommended AQMG default parameters were used whenever applicable.

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Table A-0-3 Selected CALMET Wind Field Model Options

Parameter Option Selected AQMG Default

Froude Number Adjustment Effects Calculated? Yes

Kinematic Effects Computed? No

Slope Effects Computed? Yes

Surface Wind Observations Extrapolated to Upper Layers? Yes

Surface Winds Extrapolated even if Calm? No

Maximum Radius of Influence over Land in the Surface

Layer (RMAX1) 5 km No default

Maximum Radius of Influence over Land Aloft (RMAX2) 20 km No default

Radius of Influence of Terrain Features 10 km No default

Relative Weighting of the First Guess Field and

Observations in the Surface Layer (R1) 3 km No default

Relative Weighting of the First Guess Field and

Observations in the Layers Aloft (R2) 5 km No default

A-2.2.5 CALMET Quality Assurance and Control

When generating model results it is essential to determine if the output is appropriate and reasonable

when compared with observational data. This section outlines the quality assurance and control

(QA/QC) procedures implemented upon the CALMET modelling results to determine the suitability of

the modelling output.

Wind

An example output wind field from CALMET is shown in Figure A-9 for the 10 m level on November 10,

2000 at 11 am.

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Note: Location of Harvest Power is indicated by the

Figure A-9 Example Wind Field Generated by CALMET for the 10 m Level for the Hour Ending

at 11:00 on November 10, 2000

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Data was extracted from the Level 1 (10 m level) CALMET output for a grid cell located at the facility

site. This data was then compared with the closest surface stations used in the modelling (Annacis

Island and T17 - Richmond South), as well as MSC Vancouver International Airport. The frequency

distribution of measured surface winds for the surface stations and the predicted values from the

extracted CALMET point are shown below in Figure A-10. The CALMET output follows a similar trend to

that of the surface stations, with wind speed frequencies generally falling in between those observed

at the surface stations.

Figure A-10 Frequency Distribution of Surface (10 m level) Winds for Surface Stations and near

Harvest Power (CALMET)

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Figure A-11 and Figure A-12 below show monthly and diurnal variations respectively for the surface

stations and the extracted CALMET point. The extracted point falls between the values measured at

the surface stations, and follows similar trends to the nearby Annacis Island station.

Figure A-11 Average Monthly Wind Speeds at Surface (10 m level) for Surface Stations and

Harvest Power (CALMET)

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Figure A-12 Diurnal Wind Speed Distribution of Surface (10 m level) Winds for Surface Stations

and Harvest Power (CALMET)

Temperature

Figure A-13 shows the average monthly surface temperature and Figure A-14 shows the average hourly

temperature (binned into 3 hour intervals) for the available surface data and the extracted CALMET

output for Harvest Power. Both plots show an excellent agreement between the predicted and

observed values.

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Figure A-13 Monthly Temperatures at Surface Stations and Harvest Power (CALMET)

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Figure A-14 Hourly Temperatures at Surface Stations and the Harvest Power (CALMET)

Stability Class

The frequency distribution of predicted stability for Harvest Power was compared with the calculated

stability for Vancouver Airport (YVR). YVR was used as the other surface stations used in the modelling

did not have the required parameters to determine stability. As seen in Figure A-15, the extracted

CALMET data is in good agreement with the calculated stability from YVR.

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Figure A-15 Frequency Distribution of Stability Classes Calculated for Vancouver Airport (YVR)

and Harvest Power (CALMET) for the Modelling Period

Mixing Height

Predicted mixing heights from CALMET are shown in Figure A-16. Mixing heights are not available from

the input data, but the predicted values appear representative of typical mixing heights of a similar

location (Senes et al, 1996).

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Figure A-16 Hourly Predicted Mixing Heights for Harvest Power (CALMET)

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A-2.3 CALPUFF

The CALPUFF (version 5.8, EPA approved) model was executed to simulate dispersion of emissions from

the various sources at Harvest Power. This methodology presented in this section applies to the

original modelling domain. Identical methodology applies to the larger domain used for NO2 modelling

but with more receptors over residential areas.

A-2.3.1 CALPUFF Model Options

Table A-0-4 outlines dispersion options used in the CALPUFF modelling. Unless otherwise stated in

Table A-0-4, the applicable default regulatory options currently recommended by the BC Air Quality

Modelling Guidelines (AQMG) were used.

Table A-0-4 Selected Dispersion Options Used in CALPUFF Modelling

Parameter Option Selected AQMG Default

Terrain Adjustment Method Partial Plume Adjustment

Transitional Plume Rise Modelled

Stack Tip Downwash Modelled

Vertical Wind Shear above Stack Top Not modelled

Chemical Mechanism Not modelled Not applicable

Wet Removal Not modelled Not applicable

Dry Deposition Not modelled Not applicable

Method Used to Compute Dispersion Coefficients

Computed from internally calculated micrometeorology

Partial Plume Penetration of Elevated Inversion

Modelled

Minimum Wind Speed Allowed for Non-Calm Conditions

0.5 m/s

A-2.3.2 Model Domain and Receptors

The CALPUFF modelling domain was the same as the CALMET modelling domain. Within the domain, a

nested sampling grid of receptors was created with the following spatial distribution:

20 m spacing along the plant boundary;

50 m spacing within 500 meters of the centre of the facility;

250 m spacing within 2 km of the centre the facility;

500 m spacing within 5 km of the centre of the facility; and

1000 m spacing to beyond 5 km of the centre of the facility.

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Figure A-17 Receptor Grid for Harvest Power Modelling



Figure A-18 Layout of Harvest Power with Buildings Used in BPIP Denoted in Blue



A-2.3.3 Building Downwash

The dispersion of stack emissions near an elevated source can be significantly affected by the

building downwash effect. Building downwash refers to the turbulent wake caused by a structure

as the wind blows by it. To ensure the correct analysis of plume dispersion from Harvest Power,

the US EPA Building Profile Input Program (BPIP-PRIME) was used to analyze stack and building

dimensions for possible building wake effects. The BPIP-PRIME model determines the appropriate

height and cross wind projection of all buildings that affect plume dispersion from a stack for:

buildings within a distance of 5 times the lesser of its width or peak height from the stack, and

stacks below the Good Engineering Practice height (HGEP) calculated as:

HGEP = Hb + 1.5 x L

where: Hb is the building height

L is the lesser of the building height or the projected building width.

The BPIP-PRIME model was run using building locations and dimensions provided by Harvest Power.

The results of the BPIP-PRIME model were then used as input to the CALPUFF model, and turbulent

wake effects were simulated. As Figure C-17 shows, nearly every building was used in the BPIP

program.

A-3. References

BC Ministry of Environment (Environmental Protection Division, Environmental Quality Branch, Air

Protection Section), 2008. Guidelines for Air Quality Dispersion Modelling in British

Columbia


Scire, Joseph S. et al., 2000a. A User’s Guide for the CALMET Meteorological Model (Version 5).

Earth Tech Inc.

Scire, Joseph S. et al., 2000b. A User’s Guide for the CALPUFF Dispersion Model (Version 5). Earth

Tech Inc.

Senes et al, 1997. A Mixing Height Study for North America (1987 – 1991).


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