Emission Inventory Documentation 

Tacoma-Pierce County PM2.5 Redesignation Request and Maintenance Plan Page 1

Appendix A: Tacoma-Pierce County PM2.5 

Redesignation Request and Maintenance Plan

Emissions Inventory Documentation
Emission Inventory Documentation 

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Table of Contents

1 Introduction .............................................................................................................................. 3

2 Emissions Summaries .............................................................................................................. 3

3 Inventory Development............................................................................................................ 8

3.1 General Information .......................................................................................................... 8

3.2 Point Sources................................................................................................................... 11

3.3 Minor Stationary Sources Inventoried as Point Sources ................................................. 16

3.4 Nonpoint Sources ............................................................................................................ 16

3.4.1 Residential Wood Combustion ................................................................................. 16

3.4.2 Paved Road Dust....................................................................................................... 22

3.4.3 Petroleum Distribution.............................................................................................. 25

3.4.4 Fugitive Dust Emissions from Coal Trains............................................................... 27

3.4.5 National Emissions Inventory Categories................................................................. 29

3.5 Nonroad Mobile Sources................................................................................................. 32

3.5.1 Nonroad Mobile, Except Locomotives, Marine, and Port Sources .......................... 32

3.5.2 Locomotives.............................................................................................................. 34

3.5.3 Marine and Port of Tacoma Sources......................................................................... 35

3.6 Onroad Mobile Sources................................................................................................... 38

3.6.1 Vehicle Miles Traveled............................................................................................. 38

3.6.2 Vehicle Population.................................................................................................... 39

3.6.3 MOVES Modeling and Emissions Estimates........................................................... 39

4 Quality Assurance and Quality Control ................................................................................. 40

4.1 Quality Control Procedures............................................................................................. 41

4.2 Quality Assurance Procedures......................................................................................... 41

Appendix A1 – National Emissions Inventory Source Categories............................................... 42

Appendix A2 – Residential Wood Combustion Temperature Adjustment .................................. 43

References..................................................................................................................................... 44
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Tacoma-Pierce County PM2.5 Redesignation Request andMaintenance Plan

Emission Inventory Documentation

1 Introduction

As part of developing a state implementation plan (SIP) revision, the Washington State 

Department of Ecology (Ecology) submitted an emission inventory (EI) preparation plan (IPP) 

and prepared an inventory of direct fine particles (PM2.5) and their precursors. The precursors 

are nitrogen oxides (NOX), sulfur dioxide (SO2), volatile organic compounds (VOCs) and

ammonia (NH3). Ecology prepared nonattainment area winter day and annual inventories for the 

attainment year (2011), the final year of the maintenance plan (2026), and an interim year 

(2017).

The responsibility of the EI was a shared effort by Ecology, the Puget Sound Clean Air Agency 

(PSCAA), and the Puget Sound Regional Council. Ecology performed most of the calculations, 

ran the models, and wrote the documents while much of the specific information (i.e., sources of 

pollutants, survey data, etc.) needed for that task was provided by PSCAA. The Puget Sound 

Regional Council (PSRC) provided traffic and economic forecasting data.

This document provides documentation for the attainment year and projection year inventories 

per United States Environmental Protection Agency (EPA) inventory guidance.1

2 Emissions Summaries

Annual emissions and winter weekday emissions are presented here. Tables and charts are 

included. Tables show source types by major sector group. Sectors are abbreviated as PT -

Point Sources, NP - Nonpoint Sources, NR - Nonroad Sources, OR - Onroad Sources. 

Abbreviations for each source are shown in the table below.
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Table 1: Abbreviations Used in Emissions Summaries

Sector Source Type Abbreviation

PT1 Point Sources- Major MAJOR

PT2 Point Sources – Minor MINOR

NP Architectural Coatings ARCH

NP Commercial Cooking COOK

NP Consumer & Commercial Solvents SOLV

NP Surface Coating SURF

NP Dust – Construction DUST_CNST

NP Dust - Paved Roads DUST_PAV

NP Dust – Coal Trains DUST_RR

NP Fertilizer Application FERT

NP Gas Cans GAS_CANS

NP Gas Stations GAS_STN

NP Livestock Waste LIVE

NP Residential Fuel, except Wood FUEL

NP Residential Fuel, Wood - Certified Stoves & Inserts RWC-C

NP Residential Fuel, Wood – Firelogs RWC-LG

NP Residential Fuel, Wood – Fireplaces RWC-FP

NP Residential Fuel, Wood - Pellet Stoves RWC-PL

NP Residential Fuel, Wood - Uncertified Stoves & Inserts RWC-U

OR Onroad ONRD

NR Locomotives RR

NR Marine - Harbor Craft HARB

NR Marine - Ocean-going Vessels OCEAN

NR Marine - Pleasure Craft BOAT

NR Nonroad - Commercial COMM

NR Nonroad - Construction CNSTR

NR Nonroad - Industrial IND

NR Nonroad - Lawn and Garden LAWN

NR Nonroad - Railroad Equipment RAIL

NR Port of Tacoma, non-Marine PORT
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Figure 1: PM2.5 Winter Day Emissions in Pounds

Category 2011 2017 2026

RWC 25,519 25,355 25,788

Onroad 2,497 1,642 1,149

Dust 2,023 2,069 2,631

Point-Major 1,313 1,940 1,848

Nonroad 1,384 957 697

Other 1,025 1,136 1,266

TOTAL 33,761 33,099 33,379

Table 2: PM2.5, SO2, and NOX Emissions, Winter Weekday, lbs

Gp Source PM2.5 SO2 NOx

2011 2017 2026 2011 2017 2026 2011 2017 2026

PT1 MAJOR 1,313 1,940 1,848 1,972 3,686 3,686 6,466 7,363 7,338

PT2 MINOR 0 55 55 0 258 258 0 303 314

NP RWC-FP 5,477 5,410 5,311 93 92 90 603 596 585

NP RWC-U 13,237 12,121 11,106 173 158 145 1,211 1,109 1,016

NP RWC-C 6,421 7,418 8,927 160 187 227 883 1,035 1,260

NP RWC-PL 60 73 93 6 8 10 75 91 116

NP RWC-LG 325 333 350 0 0 0 88 90 95

NP FUEL 49 53 58 687 738 813 3,810 4,093 4,506

NP COOK 975 1,028 1,153 0 0 0 0 0 0

NP DUST_CNST 596 654 678 0 0 0 0 0 0

NP DUST_PAV 1,232 1,318 1,392 0 0 0 0 0 0

NP DUST_RR 196 96 561 0 0 0 0 0 0

OR ONRD 2,497 1,642 1,149 242 223 208 60,799 36,339 19,896

NR COMM 75 62 48 3 2 3 1,041 791 660

NR CNSTR 729 444 180 20 7 8 8,260 5,121 2,764

NR IND 52 26 16 3 2 2 990 539 499

NR LAWN 179 194 219 2 2 2 492 405 421

NR RAIL 1 1 0 0 0 0 7 5 3

NR RR 43 32 16 11 1 1 1,612 1,367 954

NR PORT 118 132 143 1,188 1,500 1,958 2,497 2,752 2,675

NR OCEAN 156 34 45 2,901 140 182 2,286 2,732 3,566

NR HARB 31 31 30 1 1 1 879 817 741

NR BOAT 0 0 0 0 0 0 7 7 6

TOTAL 33,761 33,099 33,379 7,463 7,004 7,594 92,006 65,555 47,414
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Table 3: VOC and NH3Emissions, Winter Weekday, lbs

Gp Source

VOC NH3

2011 2017 2026 2011 2017 2026

PT1 MAJOR 2,219 5,128 5,193 265 265 265

PT2 MINOR 266 2,076 2,527 0 0 1

NP RWC-FP 4,386 4,333 4,254 418 413 405

NP RWC-U 22,926 20,994 19,236 735 673 617

NP RWC-C 5,076 5,914 7,155 359 420 510

NP RWC-PL 1 1 1 6 7 9

NP RWC-LG 452 464 487 0 0 0

NP FUEL 217 234 257 766 823 906

NP COOK 143 150 169 0 0 0

NP ARCH 2,721 2,868 3,216 0 0 0

NP SURF 4,765 5,023 5,633 0 0 0

NP SOLV 12,179 12,837 14,397 0 0 0

NP GAS_STN 1,105 1,172 1,383 0 0 0

NP GAS_CANS 1,629 1,717 1,813 0 0 0

NP FERT 0 0 0 3 3 3

NP LIVE 0 0 0 0 0 0

OR ONRD 33,198 20,303 11,977 973 746 645

NR COMM 1,010 722 791 0 0 0

NR CNSTR 1,161 881 731 0 0 0

NR IND 175 64 51 0 0 0

NR LAWN 3,913 3,928 4,458 0 0 0

NR RAIL 1 1 1 0 0 0

NR RR 91 66 42 0 0 0

NR PORT 136 133 108 0 0 0

NR OCEAN 72 91 119 0 0 0

NR HARB 31 33 36 0 0 0

NR BOAT 46 30 17 0 0 0

TOTAL 97,920 89,161 84,051 3,525 3,351 3,361
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Table 4: PM2.5, SO2, and NOX Emissions, Annual, tons

Gp Source

PM2.5 SO2 NOx

2011 2017 2026 2011 2017 2026 2011 2017 2026

PT1 MAJOR 240 354 337 360 673 673 1,180 1,344 1,339

PT2 MINOR 0 10 10 0 47 47 0 55 57

NP RWC-FP 254 251 246 4 4 4 28 28 27

NP RWC-U 613 561 514 8 7 7 56 51 47

NP RWC-C 297 344 413 7 9 11 41 48 58

NP RWC-PL 3 3 4 0 0 0 3 4 5

NP RWC-LG 15 15 16 0 0 0 4 4 4

NP FUEL 4 4 5 56 60 66 311 335 368

NP COOK 181 191 214 0 0 0 0 0 0

NP DUST_CNST 114 126 130 0 0 0 0 0 0

NP DUST_PAV 209 224 237 0 0 0 0 0 0

NP DUST_RR 20 11 63 0 0 0 0 0 0

OR ONRD 359 229 150 44 40 37 10,697 6,377 3,458

NR COMM 12 10 8 0 0 0 157 120 99

NR CNSTR 140 85 34 4 1 1 1,582 981 529

NR IND 11 5 3 1 0 0 204 114 108

NR LAWN 48 51 56 1 1 1 226 165 166

NR RAIL 0 0 0 0 0 0 1 1 0

NR RR 8 6 3 2 0 0 294 249 174

NR PORT 22 24 26 217 274 357 456 502 488

NR OCEAN 28 6 8 529 25 33 417 499 651

NR HARB 6 6 5 0 0 0 160 149 135

NR BOAT 1 0 0 0 0 0 14 14 13

TOTAL 2,585 2,518 2,485 1,234 1,143 1,239 15,833 11,041 7,728
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Table 5: VOC and NH3Emissions, Annual, tons

Gp Source

VOC NH3

2011 2017 2026 2011 2017 2026

PT1 MAJOR 405 936 948 48 48 48

PT2 MINOR 49 379 461 0 0 0

NP RWC-FP 203 201 197 19 19 19

NP RWC-U 1,062 972 891 34 31 29

NP RWC-C 235 274 331 17 19 24

NP RWC-PL 0 0 0 0 0 0

NP RWC-LG 21 21 23 0 0 0

NP FUEL 18 19 21 63 67 74

NP COOK 27 28 31 0 0 0

NP ARCH 629 663 743 0 0 0

NP SURF 760 801 898 0 0 0

NP SOLV 2,265 2,388 2,678 0 0 0

NP GAS_STN 216 229 255 0 0 0

NP GAS_CANS 303 320 338 0 0 0

NP FERT 0 0 0 8 8 8

NP LIVE 0 0 0 0 0 0

OR ONRD 5,058 3,114 1,938 184 142 123

NR COMM 167 118 129 0 0 0

NR CNSTR 223 169 140 0 0 0

NR IND 35 13 11 0 0 0

NR LAWN 918 765 852 0 0 0

NR RAIL 0 0 0 0 0 0

NR RR 17 12 8 0 0 0

NR PORT 25 24 20 0 0 0

NR OCEAN 13 17 22 0 0 0

NR HARB 6 6 7 0 0 0

NR BOAT 58 33 17 0 0 0

TOTAL 12,711 11,502 10,957 374 336 325

3 Inventory Development

3.1 General Information

Ecology developed nonattainment area inventories of emissions for attainment year 2011 and 

projection years 2017 and 2026. The inventory includes annual and typical winter day emissions 

estimates of PM2.5, NOX, SO2, VOC, and NH3.

A list of sources was developed using the 2011 National Emissions Inventory (NEI), local 

knowledge, and categories as defined in the 2005 Emissions Inventory Guidance for

Implementation of Ozone and Particulate Matter National Ambient Air Quality Standards 

(NAAQS) and Regional Haze Regulations.1 The list of sources is in Appendix A1 – National 

Emissions Inventory Source Categories. We used the guidance to select estimation methods and 

gathered information necessary to develop the attainment year and projection inventories. 
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Temporal Allocation

Past exceedances of the 24-hour PM2.5 standard occurred primarily during cold days in the 

months of October through March. The design day temperature profile calculated for the SIP 

revision 2008 base year inventory was used for the maintenance plan inventories. The profile is

representative of a cold, winter-like day. It was based on temperatures measured on days 

between January 1, 2006 and December 31, 2010 when daily fine particle concentrations 

exceeded 25 μg/m3.

Figure 2: Design Day Temperature Profile

Table 6: Design Day Temperature Profile in Fahrenheit

Hour 0 1 2 3 4 5 6 7 8 9 10 11

Temperature 28 27 27 28 28 28 29 29 30 33 36 41

Hour 12 13 14 15 16 17 18 19 20 21 22 23

Temperature 43 45 46 45 41 37 34 34 34 32 32 32

The temperature profile was used to calculate residential wood combustion, onroad mobile, and 

some nonroad mobile source emissions. For other sources, winter weekday emissions were 

calculated from annual emissions using temporal allocation profiles. Methods for each category 

are described beginning in Section 3.2.

Spatial Allocation

Emissions were calculated for the nonattainment area. For sources without specific coordinates

where emissions were initially calculated at the county level, spatial surrogates were used to 

approximate both the location and magnitude of the emissions. Many of the surrogates are the 

same as or similar to the surrogates used in the Pacific Northwest's air quality prediction model, 

AIRPACT. Surrogates were allocated to the nonattainment area using GIS tools and scripts. 

Each emissions source was assigned to an appropriate surrogate. 
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Nonattainment Area emissions were estimated as:

ENAA = ECounty * SurrogateNAA / SurrogateCounty

Where ENAA = emissions in the Nonattainment Area

ECounty = emissions in county

SurrogateNAA = surrogate activity in the NAA

SurrogateCounty = surrogate activity in county.

Demographics, Employment, and Vehicle Miles Traveled Surrogates

Demographic, employment, road length, vehicle miles traveled (VMT), and vehicle population

data are used in emissions calculations for several source categories. Vehicle population for 

2011 was calculated as described in Section 3.6.2. PSRC provided the demographic, 

employment, VMT, and road length data for Pierce County and the Nonattainment Area.

2

 

Table 7: Demographic, Employment, and Vehicle Statistics with Growth from 2011 Factors

Area 2011 2017 2026

Value Value Growth Value Growth

Population

Pierce County 802,150 860,030 1.07 964,204 1.20

Pierce NAA 538,328 568,690 1.06 632,857 1.18

NAA/County ratio 0.67 0.66 0.66

Households

Pierce County 301,429 327,624 1.09 363,150 1.20

Pierce NAA 208,398 223,174 1.07 245,823 1.18

NAA/County ratio 0.69 0.68 0.68

Total Employment

Pierce County 316,777 351,060 1.11 395,106 1.25

Pierce NAA 209,798 230,101 1.10 260,043 1.24

NAA/County ratio 0.66 0.66 0.66

Construction Employment

Pierce County 19,101 20,827 1.09 21,528 1.13

Pierce NAA 11,862 12,352 1.04 12,966 1.09

NAA/County ratio 0.62 0.59 0.60

Road Length in Miles

Pierce County 3990.3 4083.7 1.02 4082 1.02

Pierce NAA 2,117 2,195 1.04 2,195 1.04

NAA/County ratio 0.53 0.54 0.54

Vehicle Miles Traveled

Pierce County 16,703,154 17,951,838 1.07 18,957,391 1.13

Pierce NAA 10,537,561 11,272,898 1.07 11,854,377 1.12

NAA/County ratio 0.63 0.63 0.63

Vehicle Population

Pierce County 645,639 685,561 1.06 745,445 1.15

Pierce NAA 407,316 430,853 1.06 466,158 1.14

NAA/County ratio 0.63 0.63 0.63
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Land Use and Land Cover Surrogates

Land use and land cover were used to spatially allocate county emissions from several source 

categories to the nonattainment area. The Environmental Protection Agency's Office of 

Information, Resources Management land use/cover data (LULC, published 1994), and the U.S. 

Geological Survey's National Land Cover Database (NLCD, published 1999) were used.

Table 8: Land Use and Land Cover in Acres

Land Use/Cover type Source Pierce Co. NAA NAA/County ratio

Confined Animal Feeding Operations LULC

code 23 205 0 0

Urban Land Use NLCD

codes 21-23 96,965 64,764 0.67

Agricultural Land Use NLCD

codes 81-84 29,841 5,331 0.18

Open Water NLCD

code 11 3,371 87,781 0.04

Inventory Tasks

To estimate emissions, four basic tasks were completed for each source category. The four tasks 

were: 1) estimate the activity level, 2) adjust/allocate the activity level (or emissions) temporally 

and spatially, 3) determine emission factors (rates) per the activity, and 4) estimate emissions. 

The tasks are described below for each source category. The summary of emissions estimates 

can be found in Section 2.

3.2 Point Sources 

Industrial, commercial or institutional stationary sources which emit criteria and/or hazardous air 

pollutants are called point sources. Major point sources are those with the potential to emit 100 

tons per year or more of any one criteria pollutant (carbon monoxide, volatile organic 

compounds, sulfur dioxide, nitrogen oxides, lead, and particulate matter) or a combination of 

criteria pollutants, and/or point sources with the potential to emit 10 tons per year or more of any 

single Hazardous Air Pollutant, or 25 tons per year or more of a combination of Hazardous Air 

Pollutants (Section 112, CAA). Facilities with a major source potential-to-emit are included in 

Title V Air Operating Permit (AOP) programs unless a facility voluntarily adopts federally 

enforceable permit limits that reduce their potential-to-emit below the criteria and HAPs 

thresholds. 

For nonattainment areas, the federal Clean Air Act defines point sources as any stationary source 

having the potential to emit 100 tons per year of a criteria pollutant. There are eleven of these

sources in the nonattainment area, discussed here as major point sources.

Simpson Tacoma Kraft (STK) is the only major point source in Ecology’s jurisdiction. The ten

other major point sources in the nonattainment area fall within the Puget Sound Clean Air 

Agency’s (PSCAA) jurisdiction. 
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For a more thorough inventory, all sources registered with PSCAA that returned inventories were 

included, even if they were not major point sources. These sources are referred to as minor 

stationary sources and their emissions will be included in this section of the EI documentation. 

In summary Tables 1, 2, 3, 4, and 5 in the introduction section of this document they are listed 

separately under PT2 – Minor.

PSCAA registers sources that could potentially emit at least:

1) 2 tons of any single hazardous air pollutant;

2) 6 tons of total HAPs; and

3) 25 tons of carbon monoxide, nitrogen oxides, particulate matter, sulfur dioxides, or 

volatile organic compounds.

Sixteen of these sources submitted emission inventory reports to PSCAA and are reported here. 

The emissions reported by these sources may be less than the required reporting limits listed 

above.

Activity Level

Individual facility throughputs and production rates determine the activity level for each facility.

Spatial and Temporal Allocation

Point sources are located by county, address and coordinates. Throughput and emissions were 

assumed uniform throughout the year and 25% of the annual total was assigned to each season.

Emission Rates and Estimates

Emissions estimates for each facility are calculated using a variety of emissions estimation 

methods: continuous emissions monitors, stack test data, mass balance, best professional 

judgment, manufacturer’s specifications, speciation profiles, EPA emission factors (e.g., AP-42), 

and/or other state, manufacturer, or research group emission factors. Methods are selected 

considering permit conditions, data availability, and resource constraints.

PSCAA Sources

For the 2011 inventory, Ecology utilized the 2011 emissions provided by PSCAA for the sources 

within their jurisdiction. One source, Graymont Western US Inc, changed their PM2.5 emission 

calculation process which resulted in higher emission rates of PM2.5 in 2012. Therefore, 2012 

emissions were used for 2011 since the source felt that these were more accurate than the 2011 

numbers.

There were seven sources that calculated only PM10 emissions for their facilities. In these cases, 

PM2.5 was assumed to be equal to PM10. These sources are: Carauster Mill Group Inc; Feed 

Commodities LLC; Frederickson Power; Simpson Lumber; Tucci & Sons Inc, McChord; Tucci 

& Sons Inc, Taylor Way; and US Oil & Refining.

In addition, PSCAA only requires sources to submit an emissions inventory if the source exceeds

the thresholds for which a source would be required to obtain a registration with PSCAA. Those 

thresholds are listed above.
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Since a facility is not required to submit an EI unless they are emitting above these amounts, 

even if there are no 2011 emissions reported for a facility in Table 9, that facility could still be 

emitting pollutants. Those emissions would be below the thresholds listed above but since there 

was no emissions inventory submitted, there is no way to know what the facility emitted that 

year. Therefore, if there is a zero in Table 9 for 2011, assume that the pollutant was unreported 

but may have emitted that pollutant at a level below the registration thresholds. Using zero 

emissions for these sources in the 2011 inventory is a conservative assumption because these 

sources were all given non-zero emissions for the future year inventories (see Table 9 below). 

Ecology Sources

Data for Simpson Tacoma Kraft was taken from the facility’s 2011 inventory. The facility 

calculated additional PM2.5 emissions that are needed for the inventory but which they are not 

required by their permit to calculate. 

2011 emissions are shown in Table 9: Point Source Emissions and Projections (tons per year).

Emissions Projections

The projection inventories were calculated using the five year max for Simpson Tacoma Kraft, 

unless the facility suggested an alternate projection based on expected facility changes. 

For PSCAA sources, facility projections were determined by PSCAA engineers through 

consultation with the facility, engineering knowledge, or using the 10 year maximum emission 

for each pollutant. 

Projection emissions are shown in Table 9.
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Table 9: Point Source Emissions and Projections (tons per year) 

Facility and Pollutant

2011 

(tons)

2017 

Projection 

(tons)

2026 

Projection

(tons)

Major?

Arclin Surfaces, LLC X

VOC 11.55 34.64 75.16

Boeing Commercial Airplane, Frederickson X

NOX 0.00 15.12 12.98

PM2.5 0.00 4.25 4.25

SO2 0.00 0.16 0.16

VOC 60.86 74.07 80.15

Caraustar Mill Group Inc Tacoma Paperboard

NOX 0.00 43.09 45.03

PM2.5 0.00 2.16 2.16

SO2 0.00 47.14 47.14

Delta Prefinishing Corp

VOC 5.96 7.10 7.69

Feed Commodities LLC

NOX 0.00 1.83 1.83

PM2.5 0.00 5.00 5.00

SO2 0.00 0.01 0.01

VOC 0.00 126.81 126.81

Frederickson Power LP X

NOX 12.00 43.00 43.00

PM2.5 9.60 38.10 38.10

SO2 0.60 2.30 2.30

VOC 4.50 17.70 17.70

General Plastics Manufacturing Co

VOC 1.32 2.63 3.29

Georgia-Pacific Gypsum LLC X

NOX 24.87 29.84 29.84

PM2.5 25.95 31.13 31.13

VOC 0.00 0.00 0.00

Graymont Western US Inc X

NOX 58.07 58.07 58.07

PM2.5 80.26 80.26 80.26

SO2 5.35 5.35 5.35

VOC 2.61 2.61 2.61

IDX - Seattle

VOC 0.00 30.72 30.72

James Hardie Building Products Inc

VOC 5.59 11.18 22.36

Jet Door LLC

VOC 0.00 3.95 3.95

Lianga Pacific Inc

NH3 0.03 0.06 0.11

VOC 33.37 109.71 176.45

Milgard Manufacturing Inc

VOC 0.00 0.00 0.00

Parker Paint Manufacturing Co Inc Professional Paint

VOC 0.00 2.25 3.94
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Facility and Pollutant

2011 

(tons)

2017 

Projection 

(tons)

2026 

Projection

(tons)

Major?

Professional Coatings Inc X

VOC 58.94 117.89 117.89

Puget Sound Energy, Frederickson X

NOX 0.00 23.49 23.49

PM2.5 0.00 1.43 1.43

SO2 0.00 4.18 4.18

VOC 0.00 0.28 0.28

Rainier Richlite Co

VOC 2.26 6.79 8.15

Shore Terminals LLC

VOC 0.00 33.75 33.75

Sierra Pacific Industries X

NOX 0.00 4.80 4.80

PM2.5 0.00 16.00 16.00

SO2 0.00 1.60 1.60

VOC 0.00 241.00 241.00

Simpson Lumber Company, LLC X

NOX 6.42 12.10 9.64

PM2.5 22.19 50.10 33.29

SO2 0.07 0.10 0.11

VOC 39.00 98.45 58.50

Simpson Tacoma Kraft X

NH3 6.00 6.00 6.00

NOX 945.00 1013.00 1013.00

PM2.5 89.40 106.80 106.80

SO2 349.00 648.30 648.30

VOC 77.00 104.00 104.00

Tacoma Fixture Co Inc

VOC 0.00 40.36 40.36

Toray Composites America Inc X

VOC 35.80 56.12 61.17

Tucci & Sons Inc McChord

NOX 0.00 4.48 4.48

PM2.5 0.00 1.23 1.23

Tucci & Sons Inc Taylor Way

NOX 0.00 5.90 5.90

PM2.5 0.00 1.62 1.62

US Oil & Refining Co X

NH3 42.35 42.45 42.45

NOX 133.75 144.35 144.35

PM2.5 12.30 26.07 26.07

SO2 4.89 10.70 10.70

VOC 114.69 189.20 189.20

Westmark Products Inc

VOC 0.00 3.62 3.62
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3.3 Minor Stationary Sources Inventoried as Point Sources

PSCAA inventoried minor stationary sources. Sources are required to report emissions from any 

criteria pollutant that equals or exceeds 25 tons per year.3 Minor stationary sources may report 

emissions for less than this threshold. For more discussion on this refer to Section 3.2. All 

reported emissions of PM2.5, NOX, SO2 , NH3 and VOCs are included in this inventory (see Table 

9). 

Minor stationary source projections were performed in the same way that major source 

projections were calculated, please refer to 3.2 Point Sources, Emissions Projections.

3.4 Nonpoint Sources

Nonpoint sources include a variety of sources such as residential wood combustion, solvent 

usage, and road dust. Nonpoint source emissions are typically estimated by multiplying an

activity level by an emission factor in mass per activity.

Emissions = Activity level x Emission Factor

Emissions estimation methods and data sources for each nonpoint source category are described 

in the sub-sections below.

3.4.1 Residential Wood Combustion

Residential wood combustion emissions were estimated using local survey data, EPA emission 

factors, local wood-burning device sales data, local change-out program statistics, and other local 

control program data.

Activity Level – Base Year 2008

The SIP revision base year 2008 inventory was the starting point for estimating 2011, 2017, and 

2026 emissions. The 2008 inventory was updated to reflect a revised number of households

estimate.2 Residential wood combustion activity was estimated using data from a residential 

wood combustion survey of 1,015 households conducted in the central Puget Sound area in 2007 

(NRC2007).4, 5 This survey is the most recent and comprehensive survey conducted in the area, 

and it solicited complete information to conduct an inventory.

The survey was used to determine the percentage of households using wood burning devices and 

the annual amount of wood burned per device for fireplaces, woodstoves, inserts, and pellet 

stoves. Woodstoves and inserts were further broken out into three categories: certified catalytic, 

certified non-catalytic, and non-certified.
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The survey included seven geographic groups. Three of the groups were used in this inventory:

Pierce Co. Urban Growth Area (UGA), Pierce Co. Non-Urban Growth Area (NUGA), and King 

County (KING). The Pierce Co. Urban Growth area survey responses were used to derive most 

of the activity parameters for the Nonattainment Area (NAA). Parameters with low numbers of 

data points (e.g., fire logs burned in a certified insert) were estimated by combining geographic 

areas to get more data points. The split between catalytic and non-catalytic certified inserts and 

woodstoves was made using the professional judgment of air quality and industry staff.

6

 

Because it was useful in the calculations, the county attainment area (AA) is included in some of 

the tables below. 

The survey gathered information on the amount of pellets, presto logs and cord wood burned. To 

calculate emissions using emission factors in lbs/ton burned, the weight of the wood burned was 

estimated. The weight of a cord of wood varies with moisture content and species type. The 

most common species reported in the survey were fir, alder, and maple. PSCAA estimated the 

bone dry (zero percent moisture) weight of a cord to be 2189 lbs. Pellets are sold in 40-lb sacks, 

and fire logs were estimated at 8 lbs per log.

Annual emissions for each wood burning device were calculated according to the following 

equation:

T/yr = (HH) x (usage fraction) x (T burned/device-yr) x (pollutant lbs /T) x (T/2000 lbs)

Where HH = number of households in the geographic area

 T = tons

The numbers of households in each of the three geographic areas were estimated by the Puget 

Sound Regional Council (PSRC). The EPA data source is reference 9. All of the other 

parameter sources and values are described in the tables below. 

Table 10: Woodstove Parameter Data Sources, Base Year 2008 

Parameter Fireplaces Inserts Woodstoves Pellet stoves

 Pierce NAA

Own device (%) UGA UGA UGA UGA

Use device (%) UGA UGA+NUGA UGA UGA+NUGA+KING

Certified (% of devices used) n/a UGA+NUGA UGA n/a

Certified non-catalytic / catalytic split (%) n/a EPA EPA n/a

Cord wood burned UGA UGA+NUGA UGA n/a

Pellets burned n/a n/a n/a Entire survey

Fire logs burned UGA UGA+NUGA UGA n/a

 Pierce AA

Own device (%) NUGA NUGA NUGA NUGA

Use device (%) NUGA NUGA NUGA UGA+NUGA+KING

Certified (% of devices used) n/a NUGA NUGA n/a

Certified non-catalytic / catalytic split (%) n/a EPA EPA n/a

Cord wood burned NUGA NUGA NUGA n/a

Pellets burned n/a n/a n/a Entire Survey

Fire logs burned NUGA NUGA NUGA n/a
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Table 11: Woodstove Parameter Values, Base Year 2008 

Parameter Fireplaces Inserts Woodstoves Pellet stoves

 Pierce NAA

Own device (%) 16 7 16 2

Use device (%) 10.8 4.8 14.7 1.1

Certified (% of devices used) n/a 70 36 n/a

Certified non-catalytic / catalytic split (%) n/a 75 / 25 75 / 25 n/a

Cord wood burned (tons) 1.0 1.8 1.9 n/a

Pellets burned (tons) n/a n/a n/a 0.7

Fire logs burned (tons) 0.01 0.03 0.01 n/a

 Pierce AA

Own device (%) 19 11 11 2

Use device (%) 10.0 9.3 8.0 1.1

Certified (% of devices used) n/a 91 50 n/a

Certified non-catalytic / catalytic split (%) n/a 87.5 /12.5 87.5 /12.5 n/a

Cord wood burned (tons) 0.9 2.0 1.1 n/a

Pellets burned (tons) n/a n/a n/a 0.7

Fire logs burned (tons) 0.01 0.01 0.03 n/a

Activity Level – Attainment Year 2011, and Projection Years 2017 and 2026

Activity was projected to each of the three inventory years using number of households, annual 

woodstove sales data, professional judgment, and PSCAA's Nonattainment Area woodstove 

change-out program statistics. PSRC provided estimated households for the Nonattainment Area

for 2011, 2017 and 2026.

The Department of Revenue tracks wood burning device sales. The county of sale and out-ofstate sales are tracked.7

 Pierce County sales plus a proportional fraction of the out-of-state sales 

were used as the Pierce County total sales (see equation below). Total sales from 2009 to 2011 

were used to calculate the number of new devices from the base year 2008 to 2011. For 2017 

and 2026, total sales from 2006 to 2012 were used to calculate an average annual sales rate of 

1,014 devices per year. The sales rate was multiplied by the number of years between the 

inventory year and the base year (i.e., inventory year – 2008) to calculate total new sales.

Total Pierce Sales Equation:

Total Pierce Sales = SalesPIERCE + [SalesOUT x SalesPIERCE / (SalesPIERCE + SalesOTHER)]

Where SalesOUT = Out of state sales to WA

SalesPIERCE = Pierce County sales

SalesOTHER = All Other Counties sales

The sales were split among the Nonattainment Area and the rest of the county according to the 

number of households in each area in the projection year. This was acceptable since the fraction 

of households using devices was about the same for each area in the base year.
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Table 12: Solid Fuel Burning Device Sales, Number of Devices, 2006-2012

Area 2006 2007 2008 2009 2010 2011 2012 Average

All Other Counties 8,132 8,163 8,828 7,457 6,640 5,669 5,148

Pierce County 874 1,164 994 909 1,022 730 786

Out of State to WA 390 421 420 828 949 995 1,183

 Total 9,396 9,748 10,242 9,194 8,611 7,394 7,117

Estimated Pierce portion of out of state sales to WA

38 53 43 90 127 114 157

Sum of Pierce sales plus out of state sales to WA portion

912 1,217 1,037 999 1,149 844 943 1,104

Table 13: New Sales from 2009 to 2011, 2017, and 2026

Area 2009-2011 2009-2017 2009-2026

Pierce NAA 2,025 6,220 12,347

Pierce AA 966 2,907 5,907

The new sales were split into three groups for each of the three survey areas: catalytic inserts & 

woodstoves (10%), non-catalytic inserts & woodstoves (70%), and pellet stoves (20%), based on 

professional judgment.8 The 2008 base year inventory was updated to reflect the catalytic vs. 

non-catalytic split. The inserts & woodstoves group was split among inserts and woodstoves 

based on the 2008 split of these device types for each area.

Other assumptions are listed below, based on professional judgment8and PSCAA's woodstove 

change-out program:

 1/3 of woodstove and pellet stove sales are replacements of existing equipment

 2/3 of woodstove and pellet stove sales are new installations

 1/3 of insert sales are replacements of existing equipment

 1/3 of insert sales are installed in existing open fireplaces

 1/3 of insert sales are new installations

 621 devices in the Nonattainment Area were changed from wood to gas/electric from 

2008-2011. These were subtracted from uncertified devices for the 2011 attainment 

inventory.

 An estimated 849 devices in the Nonattainment Area were changed from wood to 

gas/electric from 2008-7/2/2013 (date of data acquisition for this inventory). Funding 

was secured to change out an additional 1,100 devices during 2014-2015. Based on 

change out statistics from 2008 - 2013, it was estimated that 41% or 455 of the 1,100 

devices would be changed to gas/electric. Devices changed to gas/electric were 

subtracted from uncertified devices for the 2017 and 2026 projection inventories.

 Due to lack of information on fireplaces, assumed none of the new sales were fireplaces.

 All replacement devices were assumed to replace uncertified devices.
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Table 14: Number of Devices Used and Tons Burned

Parameter Pierce NAA Pierce AA

Devices Tons Devices Tons

 Base Year 2008 

Fireplace 22,226 21,624 9,058 8,389

Fireplace inserts; non-EPA certified 2,915 5,337 769 1,553

Fireplace inserts; EPA certified; non-catalytic 5,213 9,546 5,764 11,647

Fireplace inserts; EPA certified; catalytic 1,738 3,182 1,921 3,882

Woodstove; non-EPA certified 19,287 36,942 3,623 3,966

Woodstove; EPA certified, non-catalytic 8,266 15,832 2,717 2,974

Woodstove; EPA certified, catalytic 2,755 5,277 906 991

Pellet Stove 2,200 1,613 986 723

Residential Firelog Total: All Combustor Types 1,051 387

 Total 64,600 100,404 25,745 34,513

 Attainment Year 2011

Fireplace 22,092 21,493 8,927 21,493

Fireplace inserts; non-EPA certified 2,699 4,943 637 4,943

Fireplace inserts; EPA certified; non-catalytic 5,565 10,190 6,109 10,190

Fireplace inserts; EPA certified; catalytic 1,788 3,274 1,971 3,274

Woodstove; non-EPA certified 18,336 35,120 3,511 35,120

Woodstove; EPA certified, non-catalytic 9,358 17,924 3,016 17,924

Woodstove; EPA certified, catalytic 2,911 5,576 948 5,576

Pellet Stove 2,477 1,816 1,110 1,816

Residential Firelog Total: All Combustor Types 1,059 1,059

 Total 65,226 101,395 26,229 101,395

 Projection Year 2017

Fireplace 21,823 21,232 8,645 8,006

Fireplace inserts; non-EPA certified 2,340 4,286 355 717

Fireplace inserts; EPA certified; non-catalytic 6,271 11,483 6,850 13,841

Fireplace inserts; EPA certified; catalytic 1,889 3,459 2,077 4,196

Woodstove; non-EPA certified 16,916 32,400 3,269 3,578

Woodstove; EPA certified, non-catalytic 11,549 22,121 3,658 4,003

Woodstove; EPA certified, catalytic 3,224 6,176 1,040 1,138

Pellet Stove 3,033 2,224 1,376 1,009

Residential Firelog Total: All Combustor Types 1,085 414

 Total 67,046 104,465 27,269 36,902

 Projection Year 2026

Fireplace 21,425 20,844 8,220 7,613

* Fireplace inserts; non-EPA certified 1,942 3,557 0 0

* Fireplace inserts; EPA certified; non-catalytic 7,316 13,396 7,895 15,953

Fireplace inserts; EPA certified; catalytic 2,038 3,732 2,236 4,518

Woodstove; non-EPA certified 15,693 30,058 2,905 3,179

Woodstove; EPA certified, non-catalytic 14,791 28,331 4,623 5,060

Woodstove; EPA certified, catalytic 3,688 7,063 1,178 1,289

Pellet Stove 3,856 2,827 1,777 1,302

Residential Firelog Total: All Combustor Types 1,140 442

 Total 70,749 110,948 28,833 39,356

* In 2026, the calculated projected devices and tons burned in the Attainment Area were -70 and -141, respectively. 

Since this cannot occur, the device and tons burned reductions were removed from the certified non-catalytic inserts 

instead.
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Tacoma-Pierce County PM2.5 Redesignation Request and Maintenance Plan Page 21

Emission Factors

Emission factors were taken from EPA's emission factor manual, AP42, and their residential 

wood combustion tool.9,10 Most of the factors in the tool are from AP42, the Mid-Atlantic 

Regional Air Management Association (MARAMA),or Environment Canada. Certified device

PM2.5 factors were calculated using annual Washington State woodstove sales data to weigh 

emission factors in each standards class: pre-Phase I, Phase I, and Phase II. The average of prePhase I and Phase I factors were assumed for stoves and inserts sold during1990 - 1992, and 

Phase II factors were assumed for devices sold in 1993 and beyond. The last actual year of sales 

data (2012) was one of the lowest years for sales. It was used to project future year sales for 

calculating the emission factor, resulting in a conservative (high) estimate.

Table 15: Residential Wood-burning Device Sales, Washington State

Inventory Year Sales Years devices

All 1990-1992 36,567

2011 1993-2011 212,300

2017 1993-2017 256,700

2026 1993-2026 323,300

Table 16: Residential Wood Combustion Emission Factors in lbs/T Burned 

Device

PM2.5

Not Cert. or N/A pre-Ph I Ph I Ph II NOX SO2 VOC NH3

Fireplace 23.6 2.6 0.4 18.9 1.8

Inserts/Stoves, Not Cert 30.6 2.8 0.4 53 1.7

Inserts/Stoves, Cert, non-Cat. 25.8 20.0 14.6 2.28 0.4 12 0.9

Inserts/Stoves, Cert, Cat. 24.2 19.6 16.2 2 0.4 15 0.9

Pellet Stove 3.06 3.8 0.32 0.041 0.3

Residential Firelog: All 28.4 7.684 0 39.56 0

Table 17: Wtd. Average PM2.5 Emission Factors for Certified Devices in lbs/T Burned

Year non-Catalytic Catalytic

2011 16.0 17.2

2017 15.6 16.9

2026 15.4 16.8

Temporal Allocation

Residential wood combustion emissions were calculated for the design day temperature profile 

using a temperature adjustment equation based on heating degree days with a base of 50 degrees

(see Appendix A2 – Residential Wood Combustion Temperature Adjustment). The temperature 

adjustment eliminates the need for a monthly activity adjustment since the temperature 

adjustment assumes activity is directly related to temperature. The calculated daily emissions 

were adjusted to weekday activity using AIRPACT temporal allocation profile 407, which was 

calculated from the 2001 Washington State University woodstove survey.11 The profile allocates 

13.5 percent of activity to each weekday.
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Spatial Allocation

Activity and emissions were calculated specifically for the Nonattainment Area.

3.4.2 Paved Road Dust

Dust emissions are generated as vehicles pass along paved roadways and disturb the layer of 

loose material on or near the road surface. This material contains particulate matter from soil, 

brake and tire wear, exhaust, and other substances. However, the paved road dust calculation 

excludes emissions from exhaust and brake and tire wear which are estimated as part of the 

onroad mobile sources emissions (see section 3.6). Paved road dust emissions were estimated 

using vehicle miles traveled (VMT) activity from the Washington State Dept. of Transportation

(WSDOT) and the emission factor equation in AP-42.

Activity Level

Average daily VMT (ADVMT) based on the national Department of Transportation’s Highway 

Performance Monitoring System (HPMS) was obtained from WSDOT. WSDOT makes 

estimates of county ADVMT by functional (roadway) classification from HPMS.12 The HPMS 

classifications available in the WSDOT data were helpful in applying the AP-42 emission factor 

equation. Total Pierce County ADVMT from WSDOT was about 5% higher than the Puget 

Sound Regional Council's (PSRC) travel demand model VMT estimate. The travel demand 

model data was used to estimate onroad emissions, so there is a small inconsistency between the 

VMT used for the paved road dust estimate and the onroad emissions estimates.

Table 18: WSDOT 2011 Pierce County ADVMT

Road Class Rural Urban Total

Interstate 339,293 3,232,487 3,571,780

Other Freeway Expressway 0 2,757,282 2,757,282

Principle Arterial 0 3,911,320 3,911,320

Minor Arterial 649,373 3,331,841 3,981,214

Major Collector 203,903 1,133,785 1,337,688

Minor Collector 46,567 0 46,567

Local Roadway 93,268 1,775,665 1,868,933

 Total 1,332,404 16,142,380 17,474,784
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Emission Factors and Temporal Allocation

Monthly PM2.5 emission rates in grams per mile were calculated using equation 2 in EPA's 

AP42.

13, 14

 Equation 2 estimates an emission rate for annual average conditions by incorporating 

a precipitation correction factor. Daily winter emissions were calculated assuming no rainfall, 

and therefore no precipitation adjustment (equation 2a).

Eext = [ k (sL)0.91 x (W)1.02 ] (1 – P/4N) equation (2)

EDAILY = [ k (sL)0.91 x (W)1.02 ] equation (2a)

where Eext is the emission factor in g/VMT

k = g/VMT particle size multiplier (0.25 for PM2.5)

sL = silt loading in g/m2

W = mean vehicle weight (tons)

P = number of days with at least 0.01 inches of precipitation in the given month

N = number of days in the given month

EPA's AP42 recommended values for average silt loading by average daily traffic (ADT) class 

were used. The HPMS facility types were classified into the ADT classes by dividing the 

number of statewide ADVMT by the roadway mileage. The classifications are shown in Table 

19. Individual urban sampling areas are not shown in the table; however, with only minor 

exceptions, they each showed the same ADT classification as the urban average.

Table 19: WSDOT Statewide Estimated Average Daily Traffic, 2011 

Rural Interstate Free/Expr Prin Art Min Art Maj Coll Min Coll Local

Miles 467 645 1,335 1,910 8,432 6,453 40,817

ADVMT (in 1,000s) 12,531 4,873 6,172 5,867 10,690 3,185 3,260

Estimated ADT 26,815 7,551 4,623 3,072 1,268 494 80

ADT Class

> 10,000 

limited access 5,000 - 10,000 500 - 5,000 500 - 5,000 500 - 5,000 < 500 < 500

silt loading (g/m2) 0.015 0.06 0.2 0.2 0.2 0.6 0.6

Urban Interstate Free/Expr Prin Art Min Art Maj Coll Min Coll Local

Miles 297 377 1,355 2,684 2,431 0 16,540

ADVMT (in 1,000s) 29,788 14,416 24,122 20,737 8,376 0 12,051

Estimated ADT 100,320 38,273 17,804 7,727 3,446 0 729

ADT Class

> 10,000 

limited access 5,000 - 10,000 500 - 5,000 500 - 5,000 500 - 5,000 < 500 < 500

silt loading (g/m2) 0.015 0.015 0.03 0.06 0.2 0.2 0.2

Mean vehicle weight by road class was calculated from a Federal Highway Administration report 

of in-use operating weights and VMT by vehicle type and road class.15

Table 20: Mean Vehicle Weight in Tons

Rural/Urban Interstate Free/Expr Prin Art Min Art Maj Coll Min Coll Local

Rural 5.71 5.71 3.80 3.16 2.74 2.62 2.49

Urban 3.27 2.56 2.51 2.26 2.18 2.18 2.14
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Days per month of precipitation greater than 0.01 inches in 2011 were obtained for SeaTac.

Table 21: Days with Greater than 0.01 Inches of Precipitation

Month Days Month Days Month Days

01 20 05 16 09 8

02 15 06 13 10 18

03 25 07 8 11 16

04 23 08 2 12 13

Monthly and day-of-week ADVMT adjustments were provided by WSDOT.16 Weekday 

adjustments are the average of Monday-Friday adjustments.

Table 22: WSDOT Monthly Adjustment Factors, 2008

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

Rural Interstate 0.77 0.85 0.93 1.00 1.03 1.12 1.22 1.24 1.10 1.03 0.89 0.83

Other Rural Arterial 0.77 0.86 0.9 0.95 1.04 1.12 1.25 1.26 1.11 1.03 0.84 0.79

Other Rural 0.72 0.77 0.82 0.87 1.05 1.23 1.42 1.36 1.20 1.01 0.84 0.71

Urban Interstate 0.92 0.97 0.99 1.01 1.06 0.99 0.98 0.98 0.99 0.95 0.91 0.91

Other Urban Arterial 0.92 0.95 0.98 1.01 1.06 1.07 1.06 1.07 1.03 1.00 0.93 0.93

Table 23: WSDOT Day-of-Week Adjustment Factors, 2008

Road Type Weekday

Rural Interstate 98.578

Other Rural Arterial 100.584

Other Rural 97.956

Urban Interstate 105.658

Other Urban Interstate 107.052

Monthly emissions were calculated using the equation below, with E from Equation 2 above. 

Annual emissions were calculated by summing all months. Daily emissions were calculated 

using the equation below, with E from Equation 2a above (no precipitation), the January monthly 

adjustment, and with D = 1.

V x T x D x E x (lb/454 g) x (T/2000 lbs) - monthly emissions

where V = ADVMT

T = monthly VMT adjustment factor

D = number of days in month, and

E = emission factor in g/VMT

Spatial Allocation

Emissions were allocated to the Nonattainment Area using VMT as the surrogate as described in 

Section 3.1. Each inventory year's link-level VMT were the surrogates (Table 7). The VMT was

provided by PSRC and is described more fully in Section 3.6.
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Projected Emissions

Emissions for the projection years were estimated by multiplying the WSDOT ADVMT by 

PSRC's county VMT growth factors (see Table 7) and using the emission factors calculated as 

described above.

3.4.3 Petroleum Distribution

Emissions from fuel service stations result from evaporation of gasoline and gasoline vapors 

during underground tank filling, underground tank breathing and emptying, and vehicle 

refueling. Losses from fuel trucks in transit are also included here. 

Also included in this section are diesel refueling emissions. This category was estimated by the 

EPA and accepted by the Washington State Department of Ecology. The methodology behind 

the estimation will be included in the 2011 NEI Technical Support Document17 which is 

currently in draft format. 

The following information and data was taken from Ecology’s 2011 Comprehensive Emissions 

Inventory and does not include the methodology for diesel refueling emissions. 

Activity Level

Activity data for gasoline distribution is gallons of gasoline distributed. This data was taken 

from the 2011 Comprehensive emissions inventory prepared by Ecology. PSCAA did not report 

gallons of gasoline from service stations in Pierce County. Gallons of gasoline were determined 

using the equation below:

Annual gallons, county = (County licensed vehicles/Total licensed vehicles in 

Washington) x Total Gallons Gasoline sold in State 

Table 24: Gallons of Gasoline Sold in Pierce County

Licensed Vehicles in 

Pierce County

Total Licensed 

Vehicles in WA

Gallons Gasoline 

Sold in WA

Gallons of Gas Sold, 

Pierce County

601,445 5,390, 474 2,601,564,000 290,270,885

Emission Factors

Refueling

To estimate the VOC emissions from refueling of gasoline, gasoline distributed in Pierce County 

were multiplied by a VOC emission factor. The emission factor is in pounds per 1000 gallons of 

gasoline, so the gallons of gasoline are shown reported as thousand gallons. Pierce County is 

one of the six remaining counties in Washington that require Stage II vapor recovery at gas 

stations. The EPA Mobile Vehicle Emission Simulator (MOVES) model was used to generate 

VOC emission factors for each season for Pierce County, taking into account local details 

including stage II vapor recovery requirements. 

Diesel refueling emissions were added to the refueling category in Table 27.
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Table 25: Pierce County VOC Refueling Emissions, Seasonal

Season Thousand Gallons of 

Gas, Pierce County

Emission Factor

(lb/1000 gal)

Emissions (lbs) Emissions (tons)

Winter 65,818.45 .862 56,751.5 28.4

Spring 75,499.36 .827 62,472.8 31.2

Summer 77,530.82 .752 58,337.3 29.2

Fall 71,422.25 .652 46,551.5 23.3

Totals 224,113.1 112.1

Underground Tank Filling, Breathing and Emptying, and Transit

Emission rates for underground tank filling, breathing and emptying, and transit losses were taken 

from documentation released by the EPA for gasoline distribution for the 2011 National Emissions 

Inventory (NEI). Emission factors for these categories do not vary by season.

Table 26: Pierce County VOC Gasoline Distribution Emissions, Annual

Category Thousand Gallons of 

Gas, Pierce County

Emission Factor 

(lb/1000 gal)

Emissions (lbs) Emissions (tons)

Underground Tank 

Filling 290,270.885 .3 87,081.3 43.5

Breathing and 

Emptying 290,270.885 1 290,270.9 145.1

Transit 290,270.885 .06 17,416.3 8.7

Temporal Allocation

As discussed above, MOVES output was generated by season. A temporal allocation was 

determined using the ratio of gallons used per season to what was used per year. The ratio for 

the winter season was approximately 23% in Pierce County. To temporally allocate the 

emissions, the annual emissions were multiplied by 23% and then divided by the amount of days 

in the season to determine winter weekday emissions for each category.

Table 27: 2011 Pierce County VOC Gasoline Distribution Emissions, Winter Weekday

Category Annual Emission 

(lbs)

Temporal Allocation 

Factor

Winter Emissions 

(lbs)

Winter Weekday 

Emissions (lbs)

Refueling 250,772.6 .23 57,677.7 640.9

Underground Tank 

Filling 87,081.3 .23 20,028.7

222.5

Breathing and 

Emptying 290,270.9 .23 66,762.3

741.8

Transit 17,416.3 .23 4,005.7 44.5

Spatial Allocation

The nonattainment area population is 67% of the population of Pierce County, as listed in Table 

7. In order to adjust the emissions to fit the area spatially, the winter weekday emissions of 

Pierce County were multiplied by 67%.
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Table 28: 2011 Nonattainment Area Winter Weekday VOC Gasoline Distribution Emissions

Category Winter

Weekday 

Emissions (lbs)

County: NAA 

Ratio

NAA Winter 

Weekday 

Emissions (lbs)

Vehicle Refueling (including 

Diesel refueling) 640.9 .67 429.1

Underground Tank Filling 222.5 .67 146.9

Breathing and Emptying 741.8 .67 489.6

Transit 44.5 .67 29.4

Projections

Ecology projected emissions from this category using population growth provided by PSRC in 

Table 7. Projected growth for 2017 and 2026 was 1.06 and 1.18, respectively.

Table 29: Gasoline Distribution Nonattainment Area, Winter Weekday VOC Projected 

Emissions (lbs)

Category 2017 (Projected) 2026 (Projected)

Vehicle Refueling 455.1 537.1

Underground Tank Filling 158.0 186.5

Breathing_Emptying 526.8 621.7

Transit 31.6 37.3

3.4.4 Fugitive Dust Emissions from Coal Trains

Ecology is including information on coal dust generated by the transport of coal using trains. 

Currently, there are proposed increases to the export of coal from the Seattle region.

Emission Factor and Spatial Allocation

Ecology estimated the tonnage of PM2.5 from railroad transport for 2011 and projections for 2017

and 2026. The calculations for the projected years assume all proposed coal exporting will occur

as well as that expansions at Canadian facilities will allow more coal to be exported through the 

Seattle region. An equation from a study done of coal dust emissions in Canada18 was used to 

determine a Total Suspended Particulate (TSP) emission factor. This equation includes a spatial 

component (SD) that allocates the emission factor to the Nonattainment Area. 

TSP Emissions Factor (kg/27one)

= 0.1*(0.62*D)*0.6 *(365-P)/365 *(SD/D)*(100-CE)/100

Where:

D = total distance travelled by rail cars (km)

SD = rail segment length estimation for NAA (km) 

P = number of days in the year with measureable precipitation (rain and snow)

CE = Control efficiency of any applied dust control measures (%)

The TSP emission factor was then converted to pounds per ton from kilograms per tonne. Please 

note that the control efficiency increases significantly in 2017 because of revised control 

strategies imposed by BNSF as of October 2011 in their Coal Loading Rule.19
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Table 30: TSP Emission Factor for Annual Coal Train Fugitive Dust Emissions

Year D SD P CE TSP EF

(lb/ton)

2011 2414 40 177 21.25 .10803

2017 2414 40 156 85 .02288

2026 2414 40 156 85 .02288

A PM2.5 to TSP ratio taken from US EPA AP-4220 of .075, the amount of coal exported/projected 

to be escorted for the year, and the TSP emission factor are used to calculate the portion of the 

TSP emissions that are PM2.5 using the following equation:

PM2.5 Emissions (annual) = 

Tons of Coal Exported for year * TSP Emission factor * PM2.5:TSP Ratio

Table 31: Annual PM2.5 Emissions from Coal Trains in tons

Year Tons of Coal 

Exported/Projected for 

Export

Annual Tons of 

PM2.5

2011 4,863,661 19.70

2017 12,579,831 10.79

2026 73,206,881 62.80

The tons of coal exported in 2011 were available from the U.S. Energy Information 

Administration (EIA). The data is reported quarterly. 

Projected year totals of coal exported include the addition of coal exports from a facility in 

Washington that is currently in the planning phases and plans to be fully operational by 2019,

21

as well as the continued exports from Canada that travel through the nonattainment area. The 

totals from the Canadian facilities also include anticipated expansions at those sites.22,23,24

Temporal Allocation

Winter weekday emissions were calculated for coal trains by recalculating the emissions for the 

winter period. Winter is typically December, January, and February for emissions inventory 

purposes. Data for these months is captured in both the first quarter (January, February, and 

March) and the fourth quarter (October, November December) in EIA data. 2011 coal exports 

for the winter season were calculated by dividing each of these quarters by three to get a monthly 

average for that quarter. The amount of coal exported during the winter season was obtained by 

summing two months of the first quarter with one month from the fourth quarter. The 

percentage of the coal that was exported in 2011 during the winter season was determined. The 

winter percentage for 2011 was then multiplied by the annual total of the estimates of coal to be 

shipped during 2017 and 2026 to estimate the amounts that would be shipped during the winter 

season in those years.
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Another adjustment made to calculate the winter weekday was to use zero for the number of days 

of precipitation. This allows the final emissions to model the worst conditions expected in 

winter. The modified emission factor variables and resultant emission factor are listed in the 

table below.

Table 32: TSP Emission Factor for Winter Weekday Coal Train Fugitive Dust Emissions

Year D SD P CE TSP EF

(lb/ton)

2011 2414 40 0 21.25 .20974

2017 2414 40 0 85 .03995

2026 2414 40 0 85 .03995

PM2.5 Emissions were then calculated using the following equation to arrive at tons per winter 

season for 2011, 2017, and 2026.

PM2.5 Emissions (winter) = 

Tons of Coal Exported for Winter season * TSP Emission factor * PM2.5:TSP Ratio

That number was then converted to winter weekday in pounds by multiplying the tons by the 

amount of lbs per ton, 2000, and dividing by the number of days in the winter season, 90. 

Table 33: PM2.5 Emissions from Coal Trains, Winter Weekday in pounds

Year

Winter Weekday 

Emissions (lbs)

2011 195.59

2017 96.36

2026 560.75

3.4.5 National Emissions Inventory Categories

Every 3 years, EPA develops a National Emissions Inventory (NEI). EPA estimates emissions 

for all nonpoint categories. State and local air agencies may either accept the EPA estimates or 

submit their own. The final NEI is a combination of state/local and EPA estimates. For the 

categories listed below, estimates from version 1 of the 2011 NEI25 were used in the maintenance 

plan inventory.
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Table 34: Other Nonpoint Source Categories and NEI Data Source

Category NEI Source

Residential Distillate Oil and Natural Gas Combustion Ecology

Construction Dust -Roads, Commercial/Industrial/Institutional EPA

Commercial Cooking EPA

Gas Cans Ecology

Non-Industrial Commercial and Consumer Solvents Ecology and EPA

Architectural Surface Coating Ecology

Industrial Surface Coating Ecology and EPA

Livestock EPA

Fertilizer Ecology

Temporal Allocation

Annual emissions were adjusted to winter (January) weekday activity using AIRPACT temporal 

allocation profiles for month and day of week. Several of the profiles came from EPA emissions 

modeling files.26 The descriptions and category assignments are shown in the tables below. 

Table 35: Temporal Profiles, Month and Weekday

Profile Description Source

Month

262 Win=25.0%, Spr=25.0%, Sum=25.0%, Fal=25.0% (uniform) EPA

485 Win=57.0%, Spr=22.5%, Sum=1.5%, Fal=19.2% EPA

996 Win=3.7%, Spr=31.4%, Sum=28.1%, Fal=36.7% EPA

998 Win=8.7%, Spr=47.1%, Sum=22.2%, Fal=22.1% EPA

1500 Win=17.7%, Spr=25.5%, Sum=34.3%, Fal=22.6% EPA from Gilliland NH3 profile

4002 Win=21.1%, Spr=25.1%, Sum=30.6%, Fal=23.1% Architectural Coating 1996 Quarterly 

Business review revenue

4015 Win=20.7%, Spr=24.3%, Sum=30.6%, Fal=24.0% EPA NONROAD2008 model for 

Construction Equipment (SEASON.DAT)

9008 Win=24.0%, Spr=26.3%, Sum=25.3%, Fal=24.4%

2008 WSDOT urban interstate traffic 

counters

Weekday

6 Weekday average = 16.7% EPA

7 Weekday average = 14.3% (uniform) EPA

2004 Weekday average = 15.1% 2008 WSDOT urban interstate traffic 

counters

Table 36: Other Nonpoint Sources - Temporal Allocation, Month and Weekday

Category Month Day Type

Residential Distillate Oil and Natural Gas Combustion 485 7

Construction Dust - Roads, Commercial/Industrial/Institutional 4015 6

Commercial Cooking 262 6

Gas Cans - Spillage, Refilling 9008 2004

Gas Cans - Permeation, Evaporation 262 7

Non-Industrial Commercial and Consumer Solvents 262 7

Architectural Surface Coating 4002 7

Industrial Surface Coating 262 6

Livestock 1500 7

Fertilizer 996 & 998 7
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Temporal Allocation – Additional Adjustments for Construction Dust

A further adjustment was made to construction dust to account for higher soil moisture values in 

the winter. The NEI dust equations contains a multiplier of 24/PE where PE is the 30-year 

average precipitation-evaporation value from Thornthwaite’s PE Index. PM2.5 concentrations in 

the Nonattainment Area greater than or equal to 25 ug/m3from 2001-2010 occurred during OctFeb with few exceptions. A variation of Thornwaite's precipitation-evaporation equation 

(below) was used to calculate PE by month using 10 years of temperature and precipitation 

data27 from the Tacoma Narrows meteorological station. The calculated monthly PE values for 

Oct-Feb were normalized to produce a 12 month PE value representative of the winter (i.e., the 

high PM2.5 values). The normal annual PE was divided by the winter PE to produce a moisture 

adjustment factor (60%).

PE Equation

PE = ∑

12 115 [P/T-10] 10/9

where P is average monthly precipitation (inches) with 0.5 being the minimum value

T is average monthly temperature (degrees F) with 28.4 ° F being the minimum 

value used in the calculation.

Table 37: Tacoma Narrows Temperature (°F) and Precipitation (Inches), 1999-2008

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

Temperature 41.8 43 45.7 49.7 55.1 60.3 64.8 64.8 59.9 52.7 45.5 41.5 52.1

Precipitation 7.16 3.64 4.11 2.48 1.84 1.49 0.54 1.02 1.09 3.5 6.92 5.98 39.76

The calculated 60% adjustment was reasonable when compared to other information:

 PSCAA regulations specify no visible emissions

 Emissions Inventory Improvement Program estimation method applies 50% control to 

PM Nonattainment Areas

 Western Regional Air Partnership and AP42 attribute 10% - 74% control efficiency for 

watering depending on schedule and operation

Spatial Allocation

The county emissions in the NEI were allocated to the nonattainment area using spatial 

surrogates as described in Section 3.1. The surrogate for each category is shown below.

Table 38: Other Nonpoint Sources - Spatial Surrogates

Category Surrogate

Residential Distillate Oil and Natural Gas Combustion PSRC households

Construction Dust - Commercial/Industrial/Institutional NLCD urban lands

Construction Dust -Roads PSRC road miles

Commercial Cooking PSRC Population

Gas Cans PSRC population

Non-Industrial Commercial and Consumer Solvents PSRC population

Architectural Surface Coating PSRC population

Industrial Surface Coating, except Traffic Markings PSRC population

Industrial Surface Coating - Traffic Markings PSRC road miles

Livestock LULC CAFOs

Fertilizer NLDC agricultural lands
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Projected Emissions

Nonpoint projections were made using county growth factors for source activity surrogates from 

PSRC as described in Section 3.1. Emissions were projected by multiplying the emissions from 

the attainment year by growth factors for the surrogate activity. The surrogate for each category 

is shown in Table 39: Other Nonpoint Sources - Projection Surrogates

Projected Emissions = Emissions attain. year x Projection year growth factor surrogate activity

Table 39: Other Nonpoint Sources - Projection Surrogates

Category Surrogate

Residential Distillate Oil and Natural Gas Combustion PSRC households

Construction Dust - Roads, Commercial/Industrial/Institutional PSRC construction employment

Commercial Cooking PSRC Population

Gas Cans PSRC population

Non-Industrial Commercial and Consumer Solvents PSRC population

Architectural Surface Coating PSRC population

Industrial Surface Coating, except Traffic Markings PSRC population

Industrial Surface Coating - Traffic Markings PSRC road miles

Livestock Assumed constant

Fertilizer Assumed constant

3.5 Nonroad Mobile Sources

Nonroad mobile sources include all off-road vehicles and equipment. Locomotives and marine 

vessels are also included in the nonroad category.

3.5.1 Nonroad Mobile, Except Locomotives, Marine, and Port Sources

The Nonroad Mobile category includes emissions estimates from gasoline, diesel, compressed 

natural gas (CNG), and liquefied petroleum gas (LPG) fueled equipment. Emissions were 

estimated using EPA's NONROAD2008a model.28 Equipment in six categories was inventoried: 

 Lawn and Garden Equipment

 Recreational Marine Vessels

 Construction and Mining Equipment

 Commercial Equipment

 Railroad Maintenance Equipment

 Industrial Equipment

Temporal Allocation and Emission Rates

Emissions were generated for the four seasons using the seasonal temporal option in the 

NONROAD2008a model for 2011 base year and 2017 and 2026 projection years. The month of 

January, both weekday and weekend, was also chosen to represent a typical winter day scenario 

for each year as well (see Table 40). NONROAD2008a requires user input of seasonal 

meteorological and fuel parameters. The required fuel parameters are gasoline RVP and oxygen 

content; sulfur contents of gasoline, diesel (land and marine), and compressed natural gas (CNG) 

and liquefied petroleum gas (LPG); and presence of stage II vapor recovery requirements. 
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Table 40: NONROAD MODEL PARAMETERS

Year Month 

or 

Season

Fuel 

RVP

O2 

Wt. 

%

Gas 

Sulfur 

%

Diesel 

Sulfur 

%

Marine 

Diesel 

Sulfur 

%

CNG/ 

LPG 

Sulfur 

%

Min 

temp 

(°F)

Max 

temp 

(°F)

Avg 

Temp 

(°F)

EtOH 

blend 

mkt 

%

EtOH 

vol %

2011 January 14.7 3.5 0.003 0.0032 0.0236 0.003 26 47 36 100 10

2011 Win 14.7 3.5 0.003 0.0032 0.0236 0.003 34 46 42 100 10

2011 Spr 12.7 3.5 0.003 0.0032 0.0236 0.003 41 58 52 100 10

2011 Sum 10 3.5 0.003 0.0032 0.0236 0.003 53 74 67 100 10

2011 Fal 10 3.5 0.003 0.0032 0.0236 0.003 46 62 57 100 10

2017 Jan 14.7 3.5 0.0028 0.0011 0.0056 0.003 26 47 36 100 10

2017 Win 14.7 3.5 0.0028 0.0011 0.0056 0.003 34 46 42 100 10

2017 Spr 12.7 3.5 0.0028 0.0011 0.0056 0.003 41 58 52 100 10

2017 Sum 10 3.5 0.0028 0.0011 0.0056 0.003 53 74 67 100 10

2017 Fal 10 3.5 0.0028 0.0011 0.0056 0.003 46 62 57 100 10

2026 Jan 14.7 3.5 0.0028 0.0011 0.0055 0.003 26 47 36 100 10

2026 Win 14.7 3.5 0.0028 0.0011 0.0055 0.003 34 46 42 100 10

2026 Spr 12.7 3.5 0.0028 0.0011 0.0055 0.003 41 58 52 100 10

2026 Sum 10 3.5 0.0028 0.0011 0.0055 0.003 53 74 67 100 10

2026 Fal 10 3.5 0.0028 0.0011 0.0055 0.003 46 62 57 100 10

Activity Level and Spatial Allocation

The NONROAD model contains data on statewide equipment types and usage. The model 

utilizes spatial surrogates appropriate for each equipment type to disaggregate state activity 

levels to individual counties. The default surrogates were used for all equipment types except 

recreational marine vessels. The default spatial surrogate for recreational marine is water surface 

area. This method can overestimate recreational boat usage in certain counties due to the large 

areas of open water in a county’s jurisdiction. A new allocation based on county boat 

registrations was substituted for the default. Registrations for 2011 were provided by the 

Washington Department of Licensing (Table 42).29 

Emissions were allocated to the Nonattainment Area and modeling grids based on spatial 

surrogates (see Table 7 and Table 8).

Table 41: Spatial Allocations for Nonroad Sources

Category Surrogate Source

Recreational Marine Vessels Land Use: open water NLCD*

Railroad Maintenance Equipment Active Railroad Track WSDOT GIS files

Commercial Equipment Land Use: Urban NLCD

Construction and Mining Equipment Land Use: Urban NLCD

Industrial Equipment Land Use: Urban NLCD

Lawn and Garden Equipment Land Use: Urban NLCD

* National Land Cover Database30

Table 42: County Boat Registrations, 2011

County Registrations

Pierce 25359
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3.5.2 Locomotives

Emissions from Class I line haul and switch yard locomotives were estimated using EPA 

guidance and other information.31 Two Class I railroads operate in Washington: Burlington 

Northern Santa Fe Railway (BNSF) and Union Pacific Railroad (UPRR). Amtrak was also 

included in this inventory. Class 2 and 3 railroad locomotive emissions were not inventoried. A 

special Northwest International Air Quality Environmental Science and Technology Consortium 

(NW-AIRQUEST; formerly Northwest Regional Technical Center) project conducted by the 

Oregon Department of Environmental Quality (ODEQ) found that emissions from Class 2 and 3 

railroad locomotives were a small percentage of total locomotive emissions.32,33

This section does not include fugitive dust from coal trains. Please refer to 3.4.4 Fugitive Dust 

from Coal Trains for those emission calculations and emissions.

Activity Level

Activity level is measured in gallons of diesel consumed by locomotives. BNSF Railway, UPRR 

and Amtrak provided county fuel use for line haul and switch yard locomotives for 2011.

34, 35, 36

 

Activity was projected to 2017 and 2026 using the Pierce County population projection factors 

(Table 7).

Coal dust emissions from the proposed Gateway Terminal coal export facility proposal in 

Whatcom County and from Canadian exports were estimated in Section 3.4.4. Increased rail 

traffic through the nonattainment area would increase diesel PM2.5 emissions. The increase is 

not estimated in this plan. The environmental effects of the Gateway Terminal are currently 

being studied through the State Environmental Policy Act and the National Environmental Policy 

Act processes.37 More detailed emissions and effects of those emissions will be discussed in 

those environmental reviews. Without the terminal, projected locomotive PM2.5 emissions 

estimates are very small, 0.10% and 0.05% of the 2017 and 2026 daily inventories, respectively. 

Even a large increase in rail traffic would not significantly increase total daily PM2.5 emissions, 

nor cause the emissions to exceed the 2017 or 2026 emissions safety margin which is the 

difference between the maintenance year 2011 emissions and the projected year emissions.

Temporal and Spatial Adjustments

The activity information was obtained by county; therefore, no spatial adjustments were 

necessary at the county level. Emissions were allocated to the Nonattainment Area and using 

active railroad track GIS data from WSDOT as the spatial surrogate. The Nonattainment Area 

has 39% of the Pierce County line haul and passenger track. It has 100% of the yards.38

Locomotives were assumed to operate uniformly year-round per EPA guidance.39

Emission Rates

BNSF, UPRR and AMTRAK provided emissions estimates and emission factors for 2011, but 

were unable to project emissions into the future. 2017 and 2026 projection year emissions 

estimates, with the exception of SO2 were calculated using EPA Guidance.40 SO2 emissions for 

2017 and 2026 were estimated using the ratio between 2011 and each projection year emission 

factor and multiplying by the total SO2 emissions from 2011 (see Table 43). 
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Table 43: Pierce County Locomotive Emission Factors in g/gal

Type Pollutant 2011 2017 2026

Line Haul VOC 7.7 4.6 2.5

Line Haul NOx 149 114 69

Line Haul SO2 1.88 0.09 0.09

Line Haul PM2.5 4.4 2.9 1.5

Passenger VOC 8.1 4.6 1.8

Passenger NOx 167 112 64

Passenger SO2 1.88 0.09 0.09

Passenger PM2.5 4.5 2.8 1.2

Yard VOC 14 11.8 7.6

Yard NOx 235 206 144

Yard SO2 1.88 0.09 0.09

Yard PM2.5 5.3 4.5 3.1

3.5.3 Marine and Port of Tacoma Sources

Four types of marine and port sources were inventoried: ocean-going vessels, harbor vessels, 

cargo handling equipment, and port rail operations. Pleasure craft were also inventoried but 

were included in Section 3.5.1. The 2011 inventory prepared for the Puget Sound Maritime Air 

Forum by Starcrest Consulting Group, LLC (2011 PSEI) was the starting point for the 

inventories.41 The PSEI is a bottom-up, activity-based emissions inventory.

Emissions Calculations for Projection Years 2017 and 2026

Emissions were calculated by projecting the 2011 inventory to each of the evaluation years. 

Emissions for pollutant "P" were calculated:

Eyear = E2011 x A x F Where E = Emissions,

A = Activity adjustment factor

F = Fuel/engine adjustment factor for pollutant

Activity level and emission rates are described in the 2011 PSEI report. The report addressed 

PM10, PM2.5, Nox, SO2, CO, and VOC. Projections were made using local information and 

federal regulatory programs. The activity and fuel/engine adjustment factors are described in the 

Activity Level and Emission Factors sections below.

Activity Level

Activity was projected using one of two activity surrogates for each type of ship or port 

equipment: Port of Tacoma sector growth estimates,42 or Pierce County population (Table 7). 

The sector growth estimates were given as growth between 2011and 2015 (22%) and between 

2015 and 2020 (10%). The 10% growth rate between 2015 and 2020 was assumed to continue 

for the period 2020-2026. Sector growth was used to project activity for all sources except 

harbor craft. Harbor craft emissions were not readily available by type (e.g., ferry, tug, 

excursion). The 2008 base year inventory showed that emissions from ferries dominated the 

harbor craft inventory in the nonattainment area. Population was chosen to project harbor craft 

emissions since it was believed to be an appropriate surrogate for ferry activity.
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Emission Factors

Ocean-going Vessels – Hotelling & Maneuvering

Changes in emission factors due to fuel changes were estimated. On March 26, 2010, the 

International Marine Organization officially designated waters off North American coasts as an 

Emission Control Area (ECA). New engine and fuel standards apply in ECAs. Fuel sulfur 

standards are: 

 10,000 ppm starting August 2012 (1.0%)

 1,000 ppm starting January 2015 (0.1%)

In 2011, most ships used fuel with 2.7% sulfur content (2011 PSEI). Some ships switch to a low 

sulfur fuel (≤ 500 ppm) or use shore power at the Port of Tacoma. In 2011, the Port of Tacoma 

estimated that 97% of the fuel used contained 2.7% sulfur, and 3% contained 0.5% sulfur. Table 

3.22 of the 2011 PSEI provided fuel correction factors for changing sulfur content from 2.7% to 

0.5% and to 0.1%. The correction factors were used to estimate emission factor changes 

between 2011 and the projection years 2017 and 2026.

Harbor Craft

EPA's NONROAD2008 model was run for 2011, 2017, and 2026 for the largest gasoline and 

diesel powered boats. Emissions factors for harbor vessels were calculated and expressed as 

g/boat using the NONROAD model output. The ratios of the projection year to 2011 emission 

factors were calculated. The ratios were used as emission factor adjustments. The diesel fuel 

sulfur content for all years was set to 15 ppm, ultra-low sulfur diesel.

Cargo Handling Equipment

Emissions reductions are being made in cargo handling equipment, but the range of equipment 

and technologies make projections difficult. Cargo handling equipment is a small part of the 

inventory; therefore, no adjustments were made.

Port Rail

EPA provided adjustment factors for locomotives as part of their rule making activity for 

locomotives.43 For 2017 and 2026, adjustment factors were calculated as the ratio of the EPA 

projection year emission factors to the attainment year 2011 emission factors.

Temporal and Spatial Allocation

Emissions were assumed to occur uniformly throughout the year.

All ocean-going vessel hotelling, cargo handling equipment, and port rail emissions were 

assumed to occur in the Nonattainment Area. Port of Tacoma, PSCAA, and Ecology staff 

assigned a fraction of the Pierce County ocean-going vessel maneuvering and harbor craft 

emissions to the Nonattainment Area when developing the 2008 attainment year inventory. The 

fractions were retained for this inventory.
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Table 44: PSEI 2011 Pierce County Emissions (Tons), NAA Adjustment Factors, 2017 and 

2026 Activity and Emission Rate Adjustment Factors

Category Pierce County 2011 Emissions (PSEI) in Tons Adjustments

PM2.5 Nox SO2 VOC Activity NAA

Ocean-going vessels, maneuvering

2011 Emissions 0.57 9.56 8.83 0.29 0.17

 2017 Adjustment factors 0.17 0.94 0.04 1.00 1.27 0.17

 2026 Adjustment factors 0.17 0.94 0.04 1.00 1.66 0.17

Ocean-going vessels, hotelling

2011 Emissions 28 416 528 13 1

 2017 Adjustment factors 0.17 0.94 0.04 1.00 1.27 1

 2026 Adjustment factors 0.17 0.94 0.04 1.00 1.66 1

Harbor craft, diesel-powered

2011 Emissions 28 801 0 26 0.2

 2017 Adjustment factors 0.94 0.87 1.00 1.00 1.07 0.2

 2026 Adjustment factors 0.81 0.71 1.00 1.00 1.18 0.2

Harbor craft, gasoline-powered

2011 Emissions 0 1 0 1 0.2

 2017 Adjustment factors 1.00 0.93 0.98 1.00 1.07 0.2

 2026 Adjustment factors 1.00 0.91 0.97 1.00 1.18 0.2

Cargo handling equipment

2011 Emissions 10 92 214 0 1

 2017 Adjustment factors 1.00 1.00 1.00 1.00 1.27 1

 2026 Adjustment factors 1.00 1.00 1.00 1.00 1.66 1

Port locomotives, switch yard

2011 Emissions 7 230 1 17 1

 2017 Adjustment factors 0.85 0.88 1.00 0.84 1.27 1

 2026 Adjustment factors 0.58 0.61 1.00 0.54 1.66 1

Port locomotives, line haul

2011 Emissions 5 134 1 7 1

 2017 Adjustment factors 0.66 0.77 0.06 0.60 1.27 1

 2026 Adjustment factors 0.34 0.46 0.06 0.32 1.66 1

Double-counting

There is potential for double-counting in this category since it overlaps with other nonroad 

sources. The sources are briefly discussed below.

Cargo handling equipment - This equipment is counted as industrial equipment in the 

NONROAD model, but the county allocations are based on manufacturing employment, which is 

not counted as port activity (Section 3.5.1). Therefore, emissions were not subtracted from the 

NONROAD model totals.

Port of Tacoma Rail - Three companies have rail operations in or near the Port of Tacoma: 

BNSF, UP, and Tacoma Rail. Emissions from BNSF and UP were counted under the locomotive 

category (Section 3.5.2). The 2011 PSEI did not contain sufficient detail to determine whether 

any emissions from BNSF or UP may have been double counted in this section.
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3.6 Onroad Mobile Sources 

Onroad mobile source emissions come from exhaust, evaporation, and brake and tire wear. 

EPA's Motor Vehicle Emission Simulator (MOVES) model was used with local and default data 

to calculate emissions.44

MOVES may be run to produce emissions (Inventory mode) or emission rates (Rates mode). 

The winter day inventory was run in rates mode, and the annual inventory in the simpler 

inventory mode.

This section describes the major components of the equations, data sources, and process used in 

the equations to develop the emissions estimates. The major components are VMT, vehicle 

population, and the MOVES data.

3.6.1 Vehicle Miles Traveled

Two sources of VMT were used. For the annual calculation, the WA Dept. of Transportation's 

(WSDOT) Pierce County estimate was used.45 The winter day calculations relied on both the 

WSDOT Pierce County VMT and on VMT specifically allocated to the NAA provided by 

PSRC.

PSRC provided average weekday daily vehicle miles traveled (ADVMT) in the County and 

NAA for each evaluation year (2011, 2017, 2026). The WSDOT data was only available for 

2011. PSRC's VMT data was used to calculate growth factors from 2011 (Table 7). The growth 

factors were used to project the 2011 WSDOT VMT to 2017 and 2026. The PSRC ratio of NAA 

to County VMT was used to allocate the WSDOT VMT to the NAA.

PSRC's VMT estimates were produced using their travel demand model. The model estimates 

VMT over individual roadway segments called links for five different time periods throughout 

the day. There are over 9,000 links in PSRC's travel demand model within the nonattainment 

area. The periods were AM (6am-9am), MD (9am-3pm), PM (3pm-6pm), EV (6pm-10pm), and 

NT (10pm-6am). The link data included congested speed and road type.

Each link was assigned to its nearest MOVES speed bin and MOVES road type: Rural 

Restricted, Rural Unrestricted, Urban Restricted, or Urban Unrestricted. Then the VMT was 

summed by speed bin and road type for each time period.

Emissions for each time period were calculated by multiplying the summed VMT by the average 

MOVES emission factor for the time period. Daily onroad emissions were calculated by adding 

the emissions from all 5 times periods. 
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3.6.2 Vehicle Population

Vehicle population is used to determine the amount of emissions from engine starts and extended 

idling. Vehicle population in the NAA was not available. Vehicles were allocated to the NAA 

using the NAA/County ratio of VMT (Table 7). The ratio was 0.63 for each year. County 

vehicle counts are described in Appendix B.

VehPopNAA = VehPopCounty x (VMTNAA/VMTCounty)

where VehPopNAA is the vehicle population in the Nonattainment area

VehPopCounty is the vehicle population in Pierce County

VMTNAA is the VMT in the Nonattainment area

VMTCounty is the VMT in Pierce County

3.6.3 MOVES Modeling and Emissions Estimates

MOVES version 2010b was used for the maintenance plan. MOVES includes a default database 

that includes emission relevant information for the entire United States. A combination of data 

from the default database (version 20100410) and data from local sources were used for the 

budget. The MOVES Technical Guidance for SIP inventories and the MOVES User’s Guide 

were used in developing the local parameters.46, 47

MOVES may be run to produce emissions (Inventory model) or emission rates (Rates mode). 

The winter day inventory was run in rates mode, and the annual inventory in the simpler 

inventory mode.

Winter Daily Emissions

Winter day emission rates were run for Pierce County. MOVES was run in Rates mode at the 

county scale by hour for one weekday in January using the design day temperature profile. 

Emission rates were output by hour, road type, and emissions process.

The winter day calculation equation using output from MOVES' Rates mode is shown below:

E = (M x Fgmi) + (V x Fgpveh)

where E = emissions in g

M = VMT

V = vehicle population

Fgmi = emission factor in g/mi from MOVES

Fgpveh = emission factor in g/vehicle from MOVES

Annual Emissions

MOVES was run in Inventory mode at the county scale by hour for weekdays and weekend days

for each of January, April, July, and October. Emissions were output by month.
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Annual emissions were calculated according to the equation below:

EAnnual = ∑(EMonth x 3)

Where EAnnual = annual emissions

EMonth = Emissions for each of 4 months, each representing a season: Jan = 

winter, Apr = spring, Jul = summer, Oct = fall.

MOVES inputs are described in Appendix B.

4 Quality Assurance and Quality Control 

In order to provide data of sufficient quality for maintenance planning needs, the inventory 

process included quality assurance (QA) and quality control (QC) procedures. The procedures 

addressed data quality objectives of accuracy, completeness, comparability, and 

representativeness. Ecology used the following target goals for each objective:

 Accuracy: The inventory calculated and documented all estimates using acceptable 

methods. Individual source requirements and availability of data and resources affected 

estimation method selection.

 Completeness: Ecology addressed completeness by ensuring that the inventory included 

all applicable source categories, and verified that the inventory contained all the 

information required to estimate emissions.

 Representativeness: We calculated actual annual and peak PM2.5 season daily emissions 

for each evaluation year. The inventory calculations used local data wherever possible.

 Comparability: Ecology compared data by source category to the prior 2008 base year 

inventory. We corrected or justified any discrepancies greater than 20%, involving 

sources that made up greater than 5% of either the 2008 or the 2011 annual inventories. 

We compared the projection inventories to the 2011 base year inventory. We 

investigated and either corrected or justified any discrepancies between the base year and 

given projection year if they:

o were greater than the population increase percentage plus 10%, and 

o involved sources that made up greater than 5% of the 2011 or projection year 

daily inventories.

The tables below show the results of the comparability checks. Highlighted categories met the 

criteria for further investigation: Point Sources and Onroad Mobile Sources.

Point Sources increased substantially from 2011 through 2026 primarily due to the use of the ten 

year maximum for the projection of PSCAA sources. The ten year maximum was used because 

of the recent economic downturn. Ecology and PSCAA agreed that a ten year maximum would 

better characterize the future emissions from the facilities than a five year maximum which had 

been used previously for this nonattainment area. 

Onroad mobile source emissions decreased substantially from 2011 through 2026 primarily due 

to fleet turnover.
Emission Inventory Documentation 

Tacoma-Pierce County PM2.5 Redesignation Request and Maintenance Plan Page 41

Table 45: Base Year 2008 and Attainment Year 2011 Inventory Comparison

Category 2008 EI 2011 EI Discrepancy 

lbs/day % lbs/day % 2011 / 2008 %

Point Sources 979 3% 1,313 4% 1.341

Residential Wood 

Combustion

24,492 74% 25,519 76% 1.042

Residential nonWood Fuel

54 0% 49 0% 0.912

Commercial Cooking 727 2% 975 3% 1.341

Construction Dust 852 3% 596 2% 0.700

Paved Road Dust 1,284 4% 1,232 4% 0.960

Coal Train Dust 196 1%

Onroad Mobile 3,041 9% 2,497 7% 0.821

Nonroad Other 1,079 3% 1,035 3% 0.960

Locomotives 55 0% 43 0% 0.783

Marine and Port 370 1% 306 1% 0.827

TOTAL 32,933 33,761 1.025

Table 46: Attainment Year 2011 and Projection Years Inventory Comparison

Category 2011 EI 2017 EI 2026 EI Discrepancy

lbs/day % lbs/day % lbs/day % 2017/2011 2026/2011

Point Sources 1,313 4% 1,995 6% 1,903 6% 1.519 1.449

Res. Wood Comb 25,519 76% 25,355 77% 25,788 77% 0.994 1.011

Res. non-Wood Fuel 49 0% 53 0% 58 0% 1.074 1.183

Comm. Cooking 975 3% 1,028 3% 1,153 3% 1.054 1.182

Construction Dust 596 2% 654 2% 678 2% 1.098 1.138

Paved Road Dust 1,232 4% 1,318 4% 1,392 4% 1.070 1.130

Coal Train Dust 196 1% 96 0% 561 2% 0.493 2.867

Onroad Mobile 2,497 7% 1,642 5% 1,149 3% 0.658 0.460

Nonroad Other 1,035 3% 726 2% 463 1% 0.702 0.447

Locomotives 43 0% 32 0% 16 0% 0.751 0.366

Marine and Port 306 1% 198 1% 218 1% 0.648 0.713

TOTAL 33,761 33,099 33,379 0.980 0.989

4.1 Quality Control Procedures

Ecology performed calculations as appropriate for the given estimation method. QC checks were 

an integral part of calculations. We performed calculations electronically wherever possible to 

minimize errors. We made hand calculations to verify electronic calculation equations. This 

final inventory report fully documents those calculations. During the development of the report 

we made comparisons to the 2008 inventory to catch any potential errors.

4.2 Quality Assurance Procedures

Several EI staff were involved in calculating the inventories. EI staff performed the reality/peer 

review and sample calculation checks on one another's work. We used several quality assurance 

checks to address the data quality objectives: 

 reality/peer review checks, 

 sample calculations, 

 sensitivity analysis (emissions ranking), and

 range checks (see Comparability objective)
Emission Inventory Documentation 

Tacoma-Pierce County PM2.5 Redesignation Request and Maintenance Plan Page 42

Appendix A1 – National Emissions Inventory Source Categories

Table 47: 2011 National Emissions Inventory (version 1), Pierce County*

Sector Group

Tons/yr Percent Total

PM25 SO2 NOX VOC NH3 PM25 SO2 NOX VOC NH3

Event Managed Burns 82 6 8 234 16 2% 0% 0% 1% 1%

Nonpt Comm. Cook 271 40 8% 0% 0% 0% 0%

Nonpt Dust, Agric 15 0% 0% 0% 0% 0%

Nonpt

Dust, non-Res

Cnstr 177 5% 0% 0% 0% 0%

Nonpt Dust, Res Cnstr 10 0% 0% 0% 0% 0%

Nonpt Dust, Road Cnstr 136 4% 0% 0% 0% 0%

Nonpt Dust, Other 56 2% 0% 0% 0% 0%

Nonpt Dust, PavRoads 332 9% 0% 0% 0% 0%

Nonpt Dust,UnpvRoads 29 1% 0% 0% 0% 0%

Nonpt Fertilizer 0 44 0% 0% 0% 0% 2%

Nonpt Commercial 41 2 20 2 0 1% 0% 0% 0% 0%

Nonpt ResFuel, DistOil 4 79 33 1 2 0% 7% 0% 0% 0%

Nonpt ResFuel, Keros. 0 1 1 0 0 0% 0% 0% 0% 0%

Nonpt ResFuel, LPG 0 0 48 2 0 0% 0% 0% 0% 0%

Nonpt ResFuel, NGas 2 3 418 24 89 0% 0% 2% 0% 5%

Nonpt ResFuel, Wood 1,471 24 162 1,660 83 41% 2% 1% 7% 4%

Nonpt Livestock 0 1,016 0% 0% 0% 0% 53%

Nonpt Misc 0 0 2 0 0% 0% 0% 0% 0%

Nonpt Managed Burns 1 0 0 0% 0% 0% 0% 0%

Nonpt OpenBurning 75 6 26 110 2% 0% 0% 0% 0%

Nonpt BulkPlants 0 165 0% 0% 0% 1% 0%

Nonpt GasCans 0 453 0% 0% 0% 2% 0%

Nonpt GasStations 0 679 0% 0% 0% 3% 0%

Nonpt GasStat, Stg2 0 130 0% 0% 0% 0% 0%

Nonpt PetStoreTrans 0 109 0% 0% 0% 0% 0%

Nonpt Ag Pesticides 0 15 0% 0% 0% 0% 0%

Nonpt Asphalt Pav 0 235 0% 0% 0% 1% 0%

Nonpt Dry Cleaning 0 3 0% 0% 0% 0% 0%

Nonpt Graphic Arts 0 69 0% 0% 0% 0% 0%

Nonpt Solv Con/Com 0 3,381 0% 0% 0% 14% 0%

Nonpt SurfCoat, Arch 0 939 0% 0% 0% 4% 0%

Nonpt SurfCoat, Indust 0 1,134 0% 0% 0% 5% 0%

Nonpt Wastewater 0 8 2 0% 0% 0% 0% 0%

Nonrd NR Model 350 10 3,659 3,844 5 10% 1% 18% 16% 0%

Nonpt CMV 63 608 1,321 46 1 2% 50% 6% 0% 0%

Nonpt Locomotives 18 5 616 32 0 0% 0% 3% 0% 0%

Onrod Onroad 225 100 12,791 10,818 611 6% 8% 62% 44% 32%

Point Airports 8 1 8 14 0% 0% 0% 0% 0%

Point Point 205 365 1,379 416 48 6% 30% 7% 2% 3%

3,572 1,211 20,493 24,561 1,917 100% 100% 100% 100% 100%

* Does not include wildfire or biogenic emissions. Highlighted categories were included in the inventory. 

Estimates for the peach-highlighted categories were taken directly from the NEI. Ecology made new calculations 

for the categories highlighted in blue, so the estimates in the table will not match those in the maintenance plan. 

Non-highlighted categories were not included in the inventories. They are expected to be small contributors to the 

total winter nonattainment area emissions.
Emission Inventory Documentation 

Tacoma-Pierce County PM2.5 Redesignation Request and Maintenance Plan Page 43

Appendix A2 – Residential Wood Combustion Temperature Adjustment

The design day temperature profile calculated for the SIP revision 2008 base year inventory was 

used for the maintenance plan inventories. Residential wood combustion emissions were 

calculated for the design day temperature profile. The calculation is similar to the residential 

wood combustion temperature adjustment system used in the AIRPACT air quality forecasting 

model. Briefly, analysis of several PM2.5 and meteorological monitoring sites throughout the 

region showed a strong linear relationship between ambient temperature and ambient fine 

particulate concentrations at temperatures below 50 degrees Fahrenheit.48 This relationship was 

used to develop the temperature adjustment system. The adjustment system involves 

normalizing emissions to heating degree days (based on 50 degrees = HDD50), and then 

multiplying the normalized value by the heating degree days for the design day. A more detailed 

description follows.

1) Calculate baseline HDD50

Calculate annual HDD50 for woodstove survey period Sept. 2006 – Aug. 2007. This is the sum of 

the heating degree days for each day of the year. Daily min-max temperatures from the South LStreet meteorological site were used.

Annual HDD50 = ∑365 50 – Tavgi), where Tavg = the daily average temperature (sum over all 365 days).

I=1 If Tavg > 50, set the value of Tavg = 50.

 = 1299

2) Calculate emissions as tons per HDD50

Calculate annual county emissions (Tons/yr). Divide the annual emissions by the annual HDD50

calculated in step (1). The result is emissions expressed as tons per HDD50. This can be viewed 

as emissions normalized to heating degree days.

Tons/HDD50 = (Tons/yr) / HDD50/yr)

3) Calculate the design day HDD50

The design day heating degree days are calculated as (50 – average temperature for the day). 

The average temperatures used in the calculation is the average of the maximum and minimum 

temperatures for the three design day temperature profiles.

Design Day HDD50 = 50 –average temperature for the design day

 Design Day HDD50 = 50 – (46 + 27)/2 = 14

4) Calculate the design day emissions

Multiply the emissions in T/HDD50 by the design day HDD50 calculated in step (3). These are 

the final daily emissions.

Tons/day = Tons/HDD50 x HDD50
Emission Inventory Documentation 

Tacoma-Pierce County PM2.5 Redesignation Request and Maintenance Plan Page 44

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Tacoma-Pierce County PM2.5 Redesignation Request and Maintenance Plan Page 45

 

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Tacoma-Pierce County PM2.5 Redesignation Request and Maintenance Plan Page 46

 

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Emission Inventory Documentation 

Tacoma-Pierce County PM2.5 Redesignation Request and Maintenance Plan Page 47

 

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