DRAFT (February 7, 2006) 

Stage II Vapor Recovery Systems — 

Options Paper

U.S. EPA 

Office of Air Quality Planning and Standards 

Emissions Monitoring and Analysis Division 

Emissions Factors and Policy Applications Group (C339-02) 

February 7, 2006 
DRAFT (February 7, 2006) 

Disclaimer

 This document contains opinions and recommendations expressed by the Emissions 

Factors and Policy Application Group to the Ozone Policy and Strategies Group within EPA. 

These recommendations are tentative in nature and do not necessarily represent current Agency 

policy. These recommendations may or may not be adopted based upon further study. 
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Table of Contents 

Section Page 

I. Executive Summary............................................................................................................... 7 

II. Introduction............................................................................................................................ 8 

III. Background............................................................................................................................ 9 

A. Description of Stage II Vapor Recovery Systems6, 8, 9 .................................................. 10 

B. Description of ORVR..................................................................................................... 11 

C. Description of Stage II/ORVR Issues ............................................................................ 12 

D. Continued Use of Stage II VRS ..................................................................................... 12 

E. Underground Storage Tank Emissions........................................................................... 13 

F. Fugitive Emissions.......................................................................................................... 13 

G. GDF Emissions Monitoring, Inspections, and Maintenance ......................................... 14 

H. Widespread Use Determinations.................................................................................... 15 

I. Description of SIP Credit Opportunities ......................................................................... 17 

1. SIP Option for States to Include Stage II VRS in Additional Areas. ....................... 17 

2. Other SIP Credit Options.......................................................................................... 18 

IV. Stage II Discussion Meetings with Stakeholders and Vendors ........................................... 21 

A. Hertz Meeting Summary................................................................................................ 21 

B. Alliance of Automobile Manufacturers (AAM) Meeting Summary.............................. 21 

C. ARID Technologies Meeting Summary......................................................................... 22 

D. Vapor Systems Technologies, Inc. (VST) Meeting Summary....................................... 22 

E. Healy Systems, Inc. (Healy) Meeting Summary............................................................ 22 

F. EMCO Wheaton Retail Meeting Summary.................................................................... 23 

G. American Petroleum Institute (API) Meeting Summary ............................................... 23 

V. Public Meeting – September 2004....................................................................................... 24 

A. Comments from the Public Meeting and on EPA’s Issues Paper.................................. 25 

B. Stage II Vapor Recovery Systems – Balance vs. Vacuum Assist.................................. 27 

1. Comment Overview.................................................................................................. 27 

2. Discussion and Recommendation............................................................................. 28 

C. On-Board Refueling Vapor Recovery (ORVR) Control Efficiency .............................. 28 

1. Comment Overview.................................................................................................. 29 

2. Discussion and Recommendation............................................................................. 30 

D. ORVR and Stage II VRS Compatibility Issues ............................................................. 33 

1. Comment Overview.................................................................................................. 33 

2. Discussion and Recommendation............................................................................. 34 

E. Widespread Use Calculation and Date........................................................................... 38 

1. Comment Overview.................................................................................................. 38 

2. Discussion and Recommendation............................................................................. 39 

F. Phase Out of Stage II Vapor Recovery Systems ............................................................ 47 

1. Comment Summary .................................................................................................. 47 

2. Discussion and Recommendations ........................................................................... 48 

G. Phase Out of Stage II Vapor Recovery Systems in the OTR......................................... 51 

1. Comment Summary .................................................................................................. 51 
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2. Discussion and Recommendations ........................................................................... 51 

H. Stage II State Implementation Plan (SIP) Credits.......................................................... 52 

1. Comment Summary .................................................................................................. 52 

2. Discussion and Recommendations ........................................................................... 53 

I. Enhanced Vapor Recovery (EVR) .................................................................................. 58 

1. Comment Summary .................................................................................................. 58 

2. Discussion and Recommendations ........................................................................... 58 

J. Monitoring/Inspections of GDF and Stage II VRS......................................................... 60 

1. Comment Summary .................................................................................................. 60 

2. Discussion and Recommendations ........................................................................... 61 

K. Emissions Factors and Emissions Testing ..................................................................... 63 

1. Comment Summary .................................................................................................. 63 

2. Discussion and Recommendations ........................................................................... 64 

L. Exemptions for Rental Car Facilities ............................................................................. 65 

1. Comment Summary .................................................................................................. 65 

2. Discussion and Recommendations ........................................................................... 66 

M. Stage I and II Equipment and UST Emissions.............................................................. 66 

1. Comment Summary .................................................................................................. 66 

2. Discussion and Recommendations ........................................................................... 67 

N. MTBE Groundwater Contamination from UST ............................................................ 70 

1. Comment Summary .................................................................................................. 70 

2. Discussion and Recommendations ........................................................................... 70 

VI. Emissions Monitoring and Testing Data.............................................................................. 72 

A. Previous Data Collected by EPA ................................................................................... 72 

1. CARB’s Preliminary Test Report, June 1999 (GDF) ............................................... 73 

2. Phase 1 of API’s ORVR Compatibility Study (GDF) .............................................. 73 

3. Phase 2 of API’s ORVR Compatibility Study (Outside).......................................... 74 

4. Phase 2 of API’s ORVR Compatibility Study (SHED)............................................ 74 

B. Data Provided by Stakeholders ...................................................................................... 81 

1. California GDF Testing, Site 1 .................................................................................. 81 

2. California GDF Testing, Site 2 ................................................................................. 82 

3. California GDF Testing, Site 3 ................................................................................. 84 

4. Florida GDF Testing, Site 1...................................................................................... 84 

5. Missouri GDF Testing, Site 1 ................................................................................... 85 

6. Missouri GDF Testing, Site 2 ................................................................................... 86 

7. Missouri Automobile Manufacturer GDF Testing, Site 3 ......................................... 87 

8. Missouri Automobile Manufacturing GDF, Site 4 ................................................... 88 

9. New Hampshire GDF Data....................................................................................... 89 

10. Multi-State GDF Data............................................................................................. 89 

11. Vermont GDF Data................................................................................................. 93 

12. EPA’s Initial In-Use Evaporative Testing of ORVR Vehicles............................... 95 

13. EPA’s IUVP............................................................................................................ 95 

B. Other Data Found within Literature............................................................................... 96 

1. WSPA – UST vent emissions ................................................................................... 96 

2. ORS Pilot Study........................................................................................................ 96 

C. Planned Testing.............................................................................................................. 97 
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1. Florida GDF Testing, Site 2...................................................................................... 97 

2. Hertz Testing, Rental Car Facilities.......................................................................... 97 

3. New Hampshire GDF Testing .................................................................................. 97 

4. Arizona GDF Testing................................................................................................ 98 

VII. NESCAUM Widespread Use Study .................................................................................... 98 

A. Methodology for Determining Widespread Use............................................................ 99 

B. NESCAUM Provided Data ............................................................................................ 99 

C. Results of Widespread Use Analysis ........................................................................... 101 

D. Algorithm Analysis Issues ........................................................................................... 103 

E. Recommendations ........................................................................................................ 104 

VIII. Recommendations.............................................................................................................. 104 

Appendices 

 A – Brief Summaries of Data 

 B – NESCAUM Widespread Use Study Supporting Documentation

 C – Widespread Use Results for NESCAUM States
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List of Figures 

Figure Page 

1 General emissions trends expected for refueling emissions in future calendar years 

for a hypothetical State, no incompatibility excess emissions (based on API studies). ....... 17 

List of Tables 

Table Page 

Table 1. List of Stakeholder Commenters ................................................................................... 25 

Table 2. Stage II VRS Comment Summary................................................................................. 29 

Table 3. On-board Refueling Vapor Recovery (ORVR) Comment Summary............................ 32 

Table 4. ORVR and Stage II VRS Compatibility Comment Summary....................................... 35 

Table 5. Widespread Use Calculation and Date Comment Summary......................................... 43 

Table 6. Phase Out of Stage II Vapor Recovery Systems Comment Summary .......................... 49 

Table 7. Phase Out of Stage II Vapor Recovery Systems in the OTR Comment Summary ....... 52 

Table 8. Stage II State Implementation Plan (SIP) Credits Comment Summary ........................ 55 

Table 9. Enhanced Vapor Recovery (EVR) Comment Summary ............................................... 59 

Table 10. Monitoring/Inspections of Stage II VRS Comment Summary.................................... 61 

Table 11. Emissions Factors and Emissions Testing Comment Summary.................................. 64 

Table 12. Exemptions for Rental Car Facilities Comment Summary ......................................... 66 

Table 13. Stage I and II Equipment and Underground Storage Tank (UST) Emissions Comment 

Summary............................................................................................................................... 68 

Table 15. Summary of Previous Data Collected by EPA: Test Data for Excess Emissions. ..... 76 

Table 16. Pressure Data for Balance Stage II VRS Without an UST Add-on APCD ................. 82 

Table 17. Pressure Data for ORVR-Compatible Vacuum Assist Stage II VRS.......................... 83 

Table 18. Stage II VA VRS, with and without P/V Valve, with and without add-on APCD...... 85 

Table 19. Stage II Balance VRS, with P/V valve, no UST vent add-on APCD.......................... 86 

Table 20. Stage II Balance VRS, with P/V valve, no UST vent add-on APCD.......................... 86 

Table 21. No Stage II VRS, with a P/V valve, no UST vent add-on APCD ............................... 87 

Table 22. Analysis of Frequency Plots for UST Pressure for All Data and Before/After Fixing 

the Leak................................................................................................................................. 88 

Table 23. No Stage II VRS, with a P/V valve, no UST vent add-on APCD ............................... 88 

Table 24. Summary of Weekday and Weekend UST Vent Pressures (No Stage II VRS, with P/V 

valve)..................................................................................................................................... 89 

Table 25. Stage II VRS Testing and Failure Rates by State ........................................................ 91 

Table 26. Initial Pressure Decay Test Results ............................................................................. 93 

Table 27. Margin by Which Pressure Decay Test Failed ............................................................ 93 

Table 28. Equipment Problems that Contributed to Pressure Decay Test Failure....................... 94 

Table 29. Parts Found Leaking During Pressure Decay Tests..................................................... 94 

Table 30. A/L Ratio Testing Results............................................................................................ 95 

Table 31. EPA IUVP Test Results............................................................................................... 96 

Table 32. Optical Remote Sensing at an RGO with No Stage II VRS and No P/V Valve.......... 97 
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Table 33. Data Provided by NESCAUM................................................................................... 100 

Table 34. Values for Key Parameters ......................................................................................... 101

Table 35. Summary of Algorithm Analysis............................................................................... 102 

Table 36. Difference in Emissions Between ORVR only and ORVR with Stage II VRS plus IEE

............................................................................................................................................. 103

List of Acronyms 

A/L – air to liquid ratio 

API – American Petroleum Institute 

CARB – California Air Resources Board 

CE – Control efficiency 

DIPE – di-isopropyl ether 

DTC – diagnostic trouble code 

EF – emission factor 

EFPAG – Emission Factors Policy Application Group 

EVR – enhanced vapor recovery 

FPMA – Florida Petroleum Marketers Association 

GDF – gasoline dispensing facility 

GVR – Gilbarco Veeder Root 

HDGV – heavy duty gasoline vehicle 

IEE – incompatibility excess emissions 

ISD – in station diagnostics 

IUVP –In use verification program 

MTBE – methyl tertiary butyl ether 

NACS – National Association of Convenience Stores 

NESCAUM – Northeastern States for Coordinated Air Use management 

OBD – onboard diagnostics 

ORVR – onboard refueling vapor recovery 

P/V – pressure/vacuum 

RSA –Remote Sensing Air, Inc 

RVP – Reid vapor pressure 

SIGMA – Society of Independent Gasoline Marketers of America 

SII – Stage II 

TAEE – tert-amyl ethyl ether 

TAME – tertiary amyl methyl ether 

TCEQ – Texas Commission on Environmental Quality 

UST – underground storage tank 

VA – vacuum assist 

V/L – vapor returned to liquid dispensed ratio 

VMT – vehicle miles traveled 

VRS – vapor recovery system 

VST – Vapor Systems Technology, Inc. 

WSPA – Western States Petroleum Association 
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I. Executive Summary 

In order to determine how better emissions monitoring at gasoline dispensing facilities 

(GDFs) could provide emissions reductions or state implementation plan (SIP) credits, the 

Emissions Factors Policy Applications Group (EFPAG) within the Emissions, Monitoring, and 

Analysis Division of the U.S. Environmental Protection Agency’s (EPA’s) Office of Air Quality 

Planning and Standards (OAQPS) reviewed a number of interrelated emissions quantification 

and policy issues. These issues include: 

1. How to determine when “widespread use” of on-board refueling vapor recovery 

(ORVR) canisters occurs, 

2. How to phase out Stage II vapor recovery systems (VRS) once widespread use 

occurs, 

3. Whether other emissions points, such as the underground storage tank (UST) vents 

need to be controlled, 

4. Whether there are opportunities to provide State Implementation Plan (SIP) credits to 

states for certain volatile organic compound (VOC)-reduction activities at GDF, 

5. Whether potential UST pressure-related emissions exist, 

6. What are actual emissions reductions achieved by Stage II VRS, 

7. What actual emissions reductions are achieved by ORVR, and the control efficiency 

of ORVR throughout the vehicle’s life span, 

8. How to quantify excess emissions from ORVR and vacuum assist Stage II VRS 

incompatibility, 

9. Whether equity issues for existing GDF should be considered when new GDF are 

built near the widespread use date, 

10. Whether nationwide, as opposed to only nonattainment area-wide, controls are 

needed, 

11. Whether a maximum achievable control technology (MACT) or generally available 

control technology (GACT) is needed to control hazardous air pollutant (HAP) 

emissions at GDF, 

12. Whether in-station diagnostics and/or enhanced vapor recovery are needed, and 

13. Whether the emissions factors used to estimate GDF emissions are accurate. 

This paper discusses these issues and identifies options for the Ozone Policy and Strategies 

Group in OAQPS’s Air Quality Standards and Strategies Division, as well as for the Waste and 

Chemical Processes Group in OAQPS’s Emissions Standards Division, to consider in addressing 

these issues. 
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II. Introduction 

Emissions from GDF are a nationwide problem, and gasoline use in vehicles and trucks is 

increasing annually. Volatile organic compounds (VOC) and HAP are emitted from the refueling of light-duty gasoline vehicles and trucks at GDF and fugitive sources at GDF. VOC 

emissions from Stage II refueling processes were estimated to be more than 470,000 tons per 

year (ton/yr) in the 1999 version 2.0 National Emissions Inventory (1999v2 NEI).1, 2 From the 

1999v2 NEI, the HAP emissions (pollutants listed in the Clean Air Act Amendments of 1990) 

from Stage II refueling could be in the range of 22,000 to 83,000 ton/yr, based on use of 

emissions factors for baseline, reformulated, and oxygenated gasoline.3

 

The emissions points from controlled Stage II process operations include vehicle 

refueling emissions at the nozzle/fillpipe interface, spillage, UST vent breathing and emptying, 

and pressure-related fugitives. A VRS captures the vehicle refueling vapors normally emitted at 

the vehicle fill pipe and returns them to the UST.4

 A VRS also has an impact on the UST vent 

emptying emissions as the UST is emptied during refueling.5

 

When an ORVR-equipped vehicle refuels at GDF with Stage II VRS, the amount and 

composition of the vapor returned to the UST by the Stage II control system can be impacted. 

As ORVR equipment is being phased in for new vehicles, there is some concern regarding the 

compatibility of ORVR controls and Stage II controls. An increase in the amount of air (in lieu 

of gasoline vapor) returned to the vapor space of the UST will lead to gasoline evaporation, or 

vapor growth, in the UST and lead to excess emissions from the UST vent. A larger amount of 

air is returned to the UST vapor space for some Stage II vacuum assist VRS when fueling 

vehicles with ORVR controls, and therefore, the excess emissions are greater for some vacuum 

assist systems. These excess emissions are referred to “incompatibility excess emissions.” 

Currently, UST vent emissions are estimated to be relatively small compared to the 

uncontrolled refueling emissions level based on current emissions factors (ranges from

7.6 pounds of VOC per 1000 gallons of fuel dispensed [lb VOC/1,000 gal] to

11.1 lb VOC/1,000 gal for an uncontrolled refueling emissions factor to 1.0 lb VOC/1000 gal for 

UST vent and fugitive emissions).6, 7 Several Stage II equipment vendors maintain that a larger 

 

1 Draft 1999 National VOC Inventory for Gasoline Distribution. April 2003. See: 

http://www.epa.gov/ttn/chief/eiip/techreport/volume03/index.html. 

2

 The NEI emissions estimates include vehicle refueling losses, spillage losses, UST vent breathing and emptying 

losses, and fugitive losses. 

3

 A table of HAP species percentages of VOC emissions can be found at 

http://www.epa.gov/ttn/chief/eiip/techreport/volume03/iii11_apr2001.pdf. 

4

 Technical Guidance: Stage II Vapor Recovery Systems for Control of Vehicle Refueling Emissions at Gasoline 

Dispensing Facilities, Volumes I and II. U.S. Environmental Protection Agency. EPA Publication No. EPA450/3-91-022a and EPA Publication No. EPA-450/3-91-022b. November 1991. 

5

 Ref. 4, p 3-10 

6

 CARB. Uncontrolled Vapor Emissions Factor at Gasoline Dispensing Facilities. January 2000. 

7

 AP-42. Section 5.2, Transportation and Marketing of Petroleum Liquids. January 1995. See 

http://www.epa.gov/ttn/chief/ap42/ch05/final/c05s02.pdf
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source of emissions at GDF is related to positive pressure build-up in the underground storage 

tank. When the UST pressure is positive, there is potential for increased fugitive emissions and 

emissions from the UST vent. In general, if an add on pollution control device is employed to 

reduce the overall storage tank pressure while at the same time capturing and recovering vent 

emissions, the driving force for fugitive emissions and the vent emissions would be greatly 

reduced. 

In reviewing emissions quantification issues associated with Stage II VRS at GDF, we in 

EFPAG drafted an issues paper and conducted a public meeting for stakeholders. The purpose of 

the issues paper and public meeting was to allow stakeholders an opportunity to provide 

comments and input for EPA’s consideration. In addition, we met separately with a few 

stakeholders to consider their specific issues, and we met with equipment vendors to consider 

their concerns and comments. Summaries of the public meeting, as well as the stakeholder and 

vendor meetings are presented in Section II and Section III. 

III. Background 

After discussions and review within EPA, on August 12, 2004, the EMAD Division 

provided a copy of the Stage II Vapor Recovery Systems Issue Paper to stakeholders for their 

review and comment. Purposes of the Stage II Vapor Recovery Systems Issue Paper included: 

(1) Providing background information regarding available data, 

(2) Discussing EPA’s ideas regarding the definition of widespread use, 

(3) Discussing ancillary issues related to Stage II VRS, and 

(4) Soliciting comments from stakeholders. 

More specifically, EPA sought comments on the following issues discussed in the August 

12, 2004 Paper: 

# Approach for determining widespread use, including: (1) using MOBILE6 

algorithms for computing widespread use and (2) making the definition of widespread 

use specific to States, regions, or areas; 

# Options for granting SIP Credits for certain activities, including: (1) continuing 

the use of Stage II controls after the determination that widespread use has occurred, 

(2) opting to require Stage II controls in new areas, and (3) requiring improved 

monitoring for Stage II control systems to increase rule effectiveness; 

# Associated issues, including (1) the significance of UST vent emptying and breathing 

emissions, (2) the significance of fugitive emissions, and (3) the potential need for 

new emissions factors for VOC and HAP. 
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A. Description of Stage II Vapor Recovery Systems6, 8, 9

The two most common types of Stage II VRS are “vapor balance” and “vacuum assist;” 

some VRS are referred to as “hybrid” systems that are classified as vacuum assist.10, 11 The 

Society of Automotive Engineers (SAE) estimates that 53 percent of VRS in the U. S. are vapor 

balance systems and 47 percent are vacuum assist systems. California estimates that vacuum 

assist systems comprise approximately 20 percent of their VRS, while New Jersey estimates they 

have 10 percent vacuum assist VRS. The Northeast States for Coordinated Air Use Management 

(NESCAUM) believes that the percent of vacuum assist systems in their region is as high as 70 

percent. 

The vapor balance VRS is configured with a corrugated boot over the nozzle spout and is 

designed to capture displaced vapor from the vehicle fuel tank.12, 13 The vapor balance VRS 

operates based on the principle of vapor replacement and provides a vapor recovery return line to 

collect vapors from the vehicle fuel tank displaced by the incoming liquid gasoline.14 The vapor 

balance VRS depends on an adequate seal being established between the vehicle being refueled 

and the faceplate of the fueling nozzle.15, 16 As gasoline is pumped from the UST, a slight 

vacuum occurs in the UST which helps pull the vapors into the UST vapor space. 

A vacuum assist VRS is sometimes “bootless;” a vacuum (by a pump) is used to pull the 

gases back through a series of holes (perforations) in the nozzle spout during refueling to the 

headspace of the UST.17, 18 The vacuum assist Stage II VRS design concept is based on the need 

to recapture vapor from the fill pipe of non-ORVR vehicles in equal volume to the gasoline 

dispensed during refueling. In most cases, liquid along the wall of the vehicle’s fillpipe allows 

the dispensing nozzle to form a seal with the fillpipe. For most vacuum assist VRS, the UST 

vent is required to be equipped with a pressure /vacuum (P/V) valve designed to open only if the 

 

8

 Refueling Emissions Controls at Retail Gasoline Dispensing Stations in New Jersey. Prepared for API by Tech 

Environmental, Inc. July 17, 2002. 

9

 Refueling Emissions Controls at Retail Gasoline Dispensing Stations in Texas. Prepared for API by Tech 

Environmental, Inc. July 16, 2002. 

10 Ref. 4, p. 4-2 

11 Enhanced Vapor Recovery: Initial Statement of Reasons for Proposed Amendments to the Vapor Recovery 

Certification and Test Procedures for Gasoline Loading and Motor Vehicle Gasoline Refueling at Service 

Stations, Hearing Notice and Staff Report. California Environmental Protection Agency, Air Resources Board. 

February 4, 2000. pp. 7 and 8. 

12 Ref. 11, p. 8. 

13 Refueling Emissions Controls at Retail Gasoline Dispensing Stations in New Jersey. Prepared for API by Tech 

Environmental, Inc. July 17, 2002, p. 2-3. 

14 Ref. 13, p. 2-3 

15 Ref. 4, p. 4-2. 

16 Ref. 13, p. 2-3. 

17 Ref. 12, p. 8. 

18 Ref. 13, p. 2-3. 
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pressure or vacuum inside the tank increases beyond a defined threshold.19, 20 The vacuum assist 

works well with non-ORVR equipped vehicles, recapturing at least 95 percent of the vapor 

displaced by the gasoline. However, when refueling an ORVR vehicle, there are no vapors to 

recapture in the vehicle’s fill pipe and the system recaptures ambient air in a roughly equal 

volume, depending on the air to liquid ratio, to the gasoline delivered and returns it to the UST 

vapor space. 

Stage II VRS is certified to achieve, and can achieve, 95 percent control efficiency. The 

actual in-use control efficiency achieved, however, is affected by rule effectiveness and rule 

penetration. The rule effectiveness is impacted by defects/leaks or malfunctions that occur 

within the VRS. The rule effectiveness and in-use control efficiency can be improved through 

better monitoring of the VRS and more frequent oversight inspections. With more frequent 

monitoring, malfunctions and defects/leaks can be repaired more quickly and can be expected to 

reduce excess emissions, i.e., increase rule effectiveness. Rule penetration accounts for the 

number of GDF in an area that are actually subject to the Stage II control requirements (e.g., 

GDFs that dispense less than 10,000 gallons per month are exempt from Stage II controls in an 

area). 

In practice, the range of in-use control efficiencies for Stage II VRS are 62 to 92 percent 

depending on the inspection frequency (this range is for no exemptions, i.e., 100 percent rule 

penetration).21 When rule penetration is accounted for, depending on the exemption level for an 

area, the in-use control efficiency ranges from 56 to 90 percent.22 EPA Region 1 indicated that 

most of their States (Maine, New Hampshire, Vermont, Massachusetts, Connecticut, and Rhode 

Island) rely on an in-use efficiency of 84 percent for Stage II VRS in their SIP calculations.23

B. Description of ORVR 

ORVR-equipped vehicles collect the gasoline vapor displaced from the vehicle fuel tank 

during filling; the gasoline vapors are adsorbed in a canister and, sometime afterwards, are 

released to the engine. ORVR controls are expected to achieve from 95 to 98 percent reduction 

of the vehicle refueling emissions (59 FR 16273 and 16279-80; April 6, 1994). When refueling a 

vehicle with ORVR control only, the ORVR canister does not affect UST vent breathing and 

emptying losses.24 

 

19 Ref. 4, p. 4-30. 

20 Ref. 13, p. 2-3. 

21 Ref. 4, p. 4-50. 

22 Ref. 4, p. 4-54. 

23 Electronic mail communication from A. Arnold, EPA Region 1, to T. Driscoll, EPA/OAQPS/EMAD. July 29, 

2004. 

24 Stage II Comparability Study for the Northeast Ozone Transport Region. U.S. Environmental Protection Agency. 

EPA Publication No. EPA-452/R-94-011. January 1995, p. 15. 
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C. Description of Stage II/ORVR Issues 

Section 182(b)(3) of the Clean Air Act (CAA), 42 U.S.C. 7511a(b)(3), requires the 

Stage II vapor recovery program for moderate, serious, severe, or extreme ozone national 

ambient air quality standards (NAAQS) nonattainment areas. Section 202(a)(6) of the CAA, 42 

U.S.C. 7521(a)(6) requires EPA to develop standards for ORVR controls on light-duty vehicles. 

Section 202(a)(6) of the CAA also states that the section 182(b)(3) Stage II requirement shall not 

apply in moderate areas after ORVR standards are promulgated. On April 16, 1994, EPA 

promulgated regulations requiring the phase-in of ORVR controls on new vehicles. In addition, 

the CAA provides that EPA may revise or waive the Stage II control requirements of 

section 182(b)(3) for “serious” or worse ozone nonattainment areas after EPA determines that 

ORVR control systems are in “widespread use” throughout the motor vehicle fleet. 

As ORVR equipment is being phased in for new vehicles, there is some concern 

regarding the compatibility of ORVR controls and Stage II controls. When an ORVR-equipped 

vehicle refuels at GDF with Stage II VRS, the amount and composition of the vapor returned to 

the UST by the Stage II control system can be impacted. An increase in the amount of air (in 

lieu of gasoline vapor) returned to the vapor space of the UST will lead to gasoline evaporation, 

or vapor growth, in the UST and lead to excess emissions from the UST vent. A larger amount 

of air is returned to the UST vapor space for some Stage II vacuum assist VRS when refueling 

vehicles with ORVR controls, and therefore, the excess emissions are greater for some vacuum 

assist systems.25 

While considering how to define and calculate widespread use, EPA was presented with 

issues related to Stage II VRS, ORVR, and their potential for incompatibility, including: (1) 

excess vapor growth within the UST system, (2) UST system pressure build up, (3) fugitive 

emissions, and (4) gas station emissions monitoring. Subsequent sections outline and discuss 

these issues. Detailed comments from the stakeholders and options to address these issues are 

discussed in Section V. 

D. Continued Use of Stage II VRS 

Section 202(a)(6) provides that EPA may revise or waive the application of the 

requirements of section 182(b)(3) of the CAA for serious, severe, or extreme ozone 

nonattainment areas after EPA determines that ORVR control systems are in “widespread use” in 

the motor vehicle fleet. If EPA decides to revise or waive these requirements, States or areas 

could decide to repeal requirements for Stage II VRS, following demonstration of widespread 

use in the area or State. Under this scenario, there would be many serious, severe, and extreme 

counties that currently have Stage II controls that would no longer be required to have them after 

widespread use occurs. The State could also decide that the Stage II requirements will remain in 

effect. We expect a benefit to retaining Stage II VRS until all vehicles have ORVR. EPA may 

consider providing additional SIP credits where States (non-OTR) retain Stage II VRS after 

widespread use occurs. EPA could provide SIP credits from the date widespread use occurs 

(depending on the definition of widespread use chosen) until the time when combined ORVR 

and Stage II VRS emissions are no longer less than ORVR emissions only. 

 

25 Ref. 11, p. 36. 
DRAFT 2-07-06 

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E. Underground Storage Tank Emissions 

Emissions from an UST vent could result from one or more of the following conditions:26 

(1) normal emptying and breathing emissions expected from the UST vents without any Stage II 

controls during refueling (uncontrolled); (2) normal emptying and breathing emissions expected 

from the UST vents when Stage II VRS are used during refueling, both vapor balance and 

vacuum assist systems (controlled); or (3) excess emissions from the UST vent related to vapor

growth resulting from the incompatibility of combined Stage II vacuum assist VRS with ORVRequipped vehicles during refueling. (Note: The AP-42 emissions factor for UST vent emptying 

and breathing emissions also includes vapor loss between the UST and the gas pump, i.e., 

fugitive emissions.)27 Lastly and as a separate issue, some studies suggest that there are 

significant emissions from the UST vents, other than those from refueling vehicles.28

F. Fugitive Emissions 

Fugitive emissions at a GDF could result from one or more of the following: (1) the 

normal fugitive emissions expected from GDF without any Stage II controls; (2) the normal 

fugitive emissions expected from GDF when Stage II VRS is used; (3) the excess fugitive 

emissions from the GDF resulting from the incompatibility of combined vacuum assist Stage II 

VRS with ORVR-equipped vehicles during refueling; and (4) the potential fugitive emissions 

from the deterioration and aging of gasoline dispensing equipment. 

CARB studies suggest that pressure-related fugitive emissions resulting from leaks at 

GDF may be significant. Furthermore, some testing by CARB suggests that pressure-related 

fugitive emissions may increase when vacuum assist Stage II VRS is used in conjunction with 

ORVR-equipped vehicles.29 CARB test method procedures calculate pressure-related fugitive 

emissions based on pressure measurements in the system. A recent API study measured fugitive 

emissions simulated in a field laboratory setting and concluded that the CARB calculations 

overestimate fugitive emissions.30 We are reviewing data provided by vendors and plan to 

observe and have emissions testing conducted to quantify fugitive emissions under the various 

uncontrolled and controlled scenarios at GDF. 

 

26 Emissions discussed here include those from breathing and emptying and do not include emissions from filling 

(i.e., related to Stage I). 

27 AP-42. Section 5.2, Transportation and Marketing of Petroleum Liquids. January 1995. See 

http://www.epa.gov/ttn/chief/ap42/ch05/final/c05s02.pdf

28 Membranes, Molecules, and the Science of Permeation. Tedmund Tiberi. Petroleum Equipment & Technology. 

April 1999. 

29 CARB. Preliminary Draft Test Report, Total Hydrocarbon Emissions from Two Phase II Vacuum Assist Vapor 

Recovery Systems During Baseline Operation and Simulated Refueling of Onboard Refueling Vapor Recovery 

(ORVR) Equipped Vehicles. June 1999. 

30 API. ORVR Compatibility Study for the Gilbarco Vaporvac VRS. February 2004. Includes Phase 1, Phase 2 - 

Outside, and Phase 2 - SHED. 
DRAFT 2-07-06 

14

G. GDF Emissions Monitoring, Inspections, and Maintenance 

As discussed previously in the Background section, the in-use control efficiency of Stage 

II VRS ranges from 56 to 92 percent, depending on the inspection frequency and the exemption 

levels.31 After the VRS equipment is installed, associated wear and tear, malfunctions, or system 

problems can result in reduction of certified efficiency. While Stage II control systems can 

achieve 95 percent or better control efficiency, in-use efficiency is demonstrated to drop 

significantly without proper operation and maintenance.32 Data analyzed during preparation of 

the EPA’s Technical Guidance Document indicate that conducting semi-annual inspections 

provide in-use efficiencies of 92 percent, annual inspections provide in-use control efficiencies 

for Stage II VRS of 86 percent, and minimal or less frequent inspections provide 62 percent inuse efficiencies (these values assume no exemptions).33 The in-use control efficiency for 

Stage II is directly related to the inspection frequency and subsequent repair of systems. Based 

on the inspection program conducted by an area, SIP credits may be provided above the typical 

in-use efficiency demonstrated from Stage II VRS operation. 

We believe that better (and more frequent) monitoring, coupled with good operation and 

maintenance programs, results in emissions reductions. GDF include several potential VOC 

emissions points other than the refueling interface that are monitored infrequently, at best. 

Several types of improved monitoring are being conducted by States that result in increased 

control efficiencies of the Stage II VRS equipment and increased emissions reductions. 

Improved monitoring may include: (1) oversight inspections and (2) requirements for in-station 

diagnostics (ISD). 

Oversight inspections of the Stage II VRS at GDF are conducted by area inspectors and 

generally focus on Stage II VRS equipment defects and: (1) visual inspection of the nozzles, 

boots, faceplates, and hoses for cuts, tears or other disrepair (some States require more than 

visual inspections); (2) checks of the nozzle check valves, nozzle latches, etc.; (3) inspection of 

the air pollution control device (APCD) on the UST, if any (i.e., the processor); (4) on-site 

paperwork and records; and (5) confirmation that the installed VRS matches the permitted VRS. 

Some areas have an equipment checklist or an inspection form that inspectors use at each site, 

while others do not. The inspection frequency ranges from once every 5 years to two to three 

inspections each year. Some areas have priority inspection programs, where GDF with recurrent 

problems are inspected more frequently and conscientious GDF are inspected less frequently, 

perhaps only once per year.34 

Another closely related option for improved monitoring might include a maintenance 

program for dispenser components. A GDF could implement a program of scheduled 

replacement of components that may leak. In this program, each component would be datestamped and replaced on a scheduled basis, regardless of detected leaks or other 

defects/malfunctions. This maintenance program may prevent leaks from occurring. 

 

31 Ref. 4, p. 4-54. 

32 Ref. 4, p. 4-53. 

33 Ref. 4, p. 4-50. 

34 Ref. 4, pp. 6-22 through 32. 
DRAFT 2-07-06 

15

In-Station Diagnostics (ISD) is a program that measures operating parameters of the 

Stage II VRS and GDF equipment to ensure it is operating properly. The ISD program provides 

real-time monitoring of critical VRS components and signals when failure modes are detected. 

The parameters monitored depend upon the type of VRS. For vapor balance VRS, UST 

pressure, pressure drop across hose, nozzle, etc. (to detect liquid blockage), and vapor returned 

to liquid dispensed (V/L) ratio35 with a flow meter would be measured.36 For vacuum assist 

VRS, UST pressure and V/L ratio with a sensor would be measured; if the V/L ratio is out of 

limits, the vapor pump flow is adjusted to achieve the correct V/L ratio.37 If the assist VRS also 

has an air pollution control device (APCD) or processor on the UST, operating parameters of the 

APCD such as hydrocarbon concentration, flow rate, flame detection, and pressure would be 

monitored.38 California has indicated that the goal of the ISD program in their State is to bring 

the in-use control efficiency to the 90 percent currently assumed in the inventory.39 For other 

States that adopt ISD programs, SIP credits may be provided if it is determined that the in-use 

control efficiency in their SIP has been exceeded. 

H. Widespread Use Determinations 

As previously mentioned, when EPA determines that ORVR control systems are in 

widespread use throughout the motor vehicle fleet, States will have the option to remove Stage II 

VRS. This determination has several components, including: (1) defining “widespread use,” (2) 

predicting when it will occur, and (3) how it can be demonstrated and verified. We know the 

definition and occurrence of widespread use is integral for State and local air pollution control 

agencies, so they can revise their control strategies and update their SIPs. Some of the ways to 

interpret and define widespread use include: 

 a. When “x” percent of the vehicles in service are ORVR-equipped, 

b. When “x” percent of the vehicle miles traveled (VMT) are from ORVR-equipped 

vehicles, 

c. When the total VOC emissions from ORVR-equipped vehicles are equal (or 

equivalent) to the total VOC emissions from Stage II VRS programs, or 

 d. When “x” percent of gasoline sold is dispensed to ORVR-equipped vehicles. 

Some of the widespread use definitions are simple approaches and some are more 

complex. In each of these definitions, the requirement for what percentage represents 

widespread use would be established first (i.e., 95 percent, 90 percent, 85 percent, etc.). The 

analysis/computation would then be conducted based on State-specific data, or region-specific 

 

35 The vapor returned to liquid dispensed (V/L) ratio is an important operating factor of VRS. The V/L ratio is also 

referred to as the air returned to liquid dispensed, or A/L ratio. The V/L ratio refers to the ratio of the quantity of 

vapor and air returned to the UST headspace to the quantity of gasoline pumped out of the UST. 

36 Ref. 11, p. 66. 

37 Ref. 11, p. 67. 

38 Ref. 11, p. 67-68. 

39 Ref. 11, p. 94. 
DRAFT 2-07-06 

16

data if a larger or smaller area than a State would be analyzed. Each of the possible definitions 

are discussed below, along with the advantages and disadvantages of each. 

Definition (a) (percentage of ORVR-equipped vehicles). Definition (a) is a simple 

approach for widespread use. In this definition, the analysis would be conducted based on 

vehicle registration data, projections of that data into the future, and the phase-in schedule for 

ORVR. While the approach accurately represents the vehicle fleet, it is important to note that 

more vehicle miles are traveled for newer vehicles, as people tend to drive newer vehicles more 

often and for longer trips than older vehicles. Definition (a) does not reflect this, and also does 

not reflect some general differences in vehicles such as fuel economy (miles per gallon) and 

useful life. 

Definition (b) (percentage of VMT by ORVR-equipped vehicles). Definition (b) is also 

a fairly simple approach. Definition (b) would be based on all of the data inputs for definition 

(a) plus the VMT data by class of vehicle. This approach addresses the VMT by ORVR vehicles 

issue mentioned under definition (a); an area or State is more likely to reach the criterion in 

definition (b) before reaching the criterion in definition (a) (i.e., widespread use would occur 

earlier with definition (b)). VMT data are generally available for States and regions. This 

approach may not address differences in vehicles such as fuel economy (miles per gallon) and 

useful life. 

Definition (c) (VOC emissions with ORVR controls equal VOC emissions with Stage II 

VRS only). Definition (c) is a slightly more complex approach that would require calculation 

and comparison of vehicle refueling emissions based on two different refueling control 

measures. This definition would require the data inputs for definitions (a) and (b) along with 

data on ambient temperature, Reid vapor pressure, rule effectiveness, rule penetration, and the 

percentage of GDF with vacuum assist Stage II VRS (to determine incompatibility excess 

emissions). The advantage of this approach is that it addresses and compares emissions levels 

directly. A disadvantage with this approach is that the in-use control efficiency of the Stage II 

VRS must be correctly determined (range was provided as 56 to 90 percent).40

Definition (d) (gasoline dispensed to ORVR-equipped vehicles). Definition (d) would 

require data on the volume of gasoline sold in addition to the data inputs needed for 

definition (b). A disadvantage of this approach is that gasoline quantities dispensed typically are 

not available on a county or area basis and must be estimated based on either VMT data and fuel 

economies or county gasoline sales (in dollars). This approach does, however, address 

differences in vehicles such as fuel economy for each vehicle type. Included as part of the 

Regulatory Impact Analysis (RIA) conducted for the ORVR regulations in January 1994, the 

widespread use analysis was based on gasoline dispensed to ORVR-equipped vehicles.41

 

40 Ref. 4, p. 4-54. 

41 Final Regulatory Impact Analysis: Refueling Emission Regulations for Light Duty Vehicles and Trucks and 

Heavy Duty Vehicles. U.S. Environmental Protection Agency, Office of Mobile Sources. January 1994. 
DRAFT 2-07-06 

17

I. Description of SIP Credit Opportunities 

In prior meetings and discussions with stakeholders, several questions arose regarding 

SIP credits related to the widespread use date and Stage II control requirements. The questions 

include how SIP credits might be impacted by: (1) continuing to use Stage II controls after the 

widespread use date, (2) requiring Stage II controls in new areas, and (3) applying improved 

monitoring to Stage II control systems to decrease emissions and increase rule effectiveness. 

Figure 1 shows the relative emissions for several control measures and in-use efficiencies. The 

figure shows the full range of possible in-use efficiencies and their relation to the ORVR only 

control scenario (point B versus point B’ depending on the Stage II control efficiency). The 

figure also shows that the combined use of ORVR and Stage II VRS controls results in lower 

VOC emissions than either control measure alone. If a State applied both control measures in its 

projected emissions baseline, it could not receive additional SIP credit for those same measures, 

i.e., to avoid double-counting. 

0

2

4

6

8

10

12

14

16

18

2005 2010 2015 2020 2025 2030 2035

Future Calendar Years

V

OC (tons s/ um

mer day)

Stage II Controls Only_90% IUE

Stage II Controls Only_56% IUE 

ORVR Only

Stage II Controls (90%IUE) with ORVR and No

Incompatibility Excess Emissions

Stage II Controls (56% IUE) with ORVR and No

Incompatibility Excess Emissions

Point B

Point B'

Figure 1. General emissions trends expected for refueling emissions in future calendar years for a 

hypothetical State, no incompatibility excess emissions (based on API studies). 

1. SIP Option for States to Include Stage II VRS in Additional Areas. 

States could require Stage II VRS in areas where they are not currently required and/or 

located, even knowing that Stage II VRS may not be required after relatively few years. Under 

the new 8-hr ozone designations: (1) several MSAs were revised and additional counties were 

included in ozone nonattainment areas, (2) several MSAs that were serious or severe under the 1-

hour standard are newly classified as moderate under the 8-hour ozone standard, and (3) several 
DRAFT 2-07-06 

18

areas have been newly classified as ozone nonattainment areas (added to the moderate 

nonattainment classification). Where MSAs were revised and counties were added and the 

MSAs were previously classified as serious or severe, the added counties are not likely to have 

Stage II controls in place. If the State decides to retain Stage II controls in these MSAs after the 

widespread use date, States could require these added counties to also control Stage II emissions. 

In the second scenario, a State could require Stage II in moderate nonattainment areas that have 

been newly added to the ozone nonattainment areas. 

State and local agencies may be reluctant to require Stage II VRS for a limited number of 

years. However, some States may be interested in requiring Stage II VRS for GDF that are not 

currently required to have Stage II controls, if adequate SIP credits are granted. A few moderate 

areas (outside of OTR) retained Stage II controls following the April 1994 promulgation of 

ORVR controls (e.g., counties in Florida). If SIP credits can be granted for requiring Stage II 

VRS in additional areas, the credit calculation would include the emissions reductions that reflect 

combined Stage II and ORVR controls. For these counties, the emissions from GDF would be 

affected significantly. 

2. Other SIP Credit Options. 

SIP credit may also be an option for States where stations install UST vent controls or 

other control measures after Stage II VRS requirements are removed. The other control 

measures may include a P/V valve or an UST add-on APCD (processor) or possibly other CARB 

EVR requirements. 

Groundwater Contamination from Stage II VRS. 

Some studies suggest that leaking USTs, including liquid leaks and possibly vapor leaks, 

are contaminating the groundwater with MTBE. MTBE is a component of gasoline and is added 

to reformulated gasoline, oxygenated fuels, and premium grades of unleaded gasoline. EPA has 

not set a national standard for MTBE in drinking water, but many States have set their own 

limits. 

EPA-promulgated federal UST regulations have contributed significantly to the reduction 

of soil and groundwater contamination (by MTBE and other fuel components). Unfortunately, 

even with these regulations in place, there are sometimes equipment failures and installation 

mistakes that result in releases of fuel to the environment; in addition, there are also some 

concerns that vapor leaks occur from the UST when the tank becomes pressurized. EPA is 

currently working with States to improve the compliance rate of the leak detection requirements 

through compliance assistance programs, UST inspections, and enforcement actions. As of 

December 22, 1998, substandard USTs not meeting requirements for spill, overfill, and corrosion 

were required to be upgraded or closed.4234 

– UST Regulations 

New UST. Federal UST regulations specify that new UST installed after December 22, 

1988 must meet four requirements: (1) that the installation of the tank and piping be certified to 

meet industry codes, (2) that the tank be installed with leak detection, (3) that the tank be 

 

42 See: http://www.epa.gov/swerust1/mtbe/index.htm 
DRAFT 2-07-06 

19

installed with spill and overfill protection, and (4) that the tank be installed with corrosion 

protection.43, 4435, 36 All of these requirements are crucial in ensuring that the UST does not 

contaminate groundwater. The leak detection requirements include three components; the leak 

detection system must: 

# Detect a leak from any portion of the tank or its piping, 

# Be calibrated, operated, and maintained as directed by manufacturer’s instructions; 

and 

# Meet performance requirements contained in 40 CFR 280.43 and 280.44. 

A GDF must conduct monthly monitoring of the UST using the leak detection system and 

must select at least one of the following methods to determine if leaks exist: 

1. Interstitial Monitoring: determine if there are leaks in the space between the UST and 

the second barrier. 

2. Automatic Tank Gauging Systems: use automation to monitor product level and 

inventory control. 

3. Monitoring for Vapors in the Soil: sample vapors in the soil surrounding the UST. 

4. Monitoring for Liquids in the Groundwater: monitor the groundwater table near the 

UST for the presence of released free product on the water table. 

5. Statistical Inventory Reconciliation: requires that a trained professional use 

sophisticated computer software to perform a statistical analysis of gasoline 

inventory, delivery, and dispensing data. 

6. Other Methods Approved by the Regulatory Authority: a comparable proven method 

to the above methods. 

As an alternative to the monthly monitoring methods, a GDF may combine inventory 

control with tank tightness testing for the first ten years after the installation of a new UST. 

After ten years have passed, the GDF would then have to use one of the six monthly monitoring 

methods mentioned above. An inventory control program consists of taking daily measurements 

of UST contents and recording deliveries and the amount of product pumped from the UST. 

This information along with daily and monthly calculations indicates if there is a leak. A tank 

tightness test must be conducted every five years. 

Leak detection monitoring is also important for UST piping. Pressurized piping must 

meet one of the following requirements: (1) piping must be installed with devices that 

automatically shut off, restrict flow, or sound an alarm; or (2) conduct an annual tightness test or 

 

43Straight Talk on Tanks: Leak Detection Methods for Petroleum Underground Storage Tanks and Piping. U.S. 

Environmental Protection Agency. EPA Publication No. EPA 510-B-97-007. September 1997. 

44 Musts for USTs: A Summary of Federal Regulation for Underground Storage Tank Systems. U.S. Environmental 

Protection Agency. EPA Publication No. EPA 510-K-95-002. July 1995. 
DRAFT 2-07-06 

20

one of the six monthly monitoring methods noted above for UST. If the UST piping is suction 

piping, the leak detection requirements are dependent on the type of suction piping used. 

New USTs must also meet spill and overfill requirements. All new installed UST must 

be installed with a catchment basin. A catchment basin, also referred to as a spill containment 

manhole or spill bucket, is a bucket sealed around the UST fillpipe. Most catchment manholes 

are equipped with pumps or drains to remove liquid spills. New USTs must also have overfill 

protection upon installation. Three commonly used overfill protection devices provide either 

automatic shutoff, overfill alarms, or ball float valves. 

Lastly, a new UST must have corrosion protection. The UST and associated components 

must be comprised of either (1) non-corrodible material such as fiberglass or jacketed in noncorrodible material, (2) made of steel that is coated with a corrosion-resistant coating and with 

cathodic protection, or (3) made of steel clad with a thick layer of non-corrodible material (does 

not apply to piping). 

Existing UST. Existing UST that were installed before December 22, 1988 were 

required to meet the leak detection requirements by December 1993. Both spill and overfill 

protection requirements and corrosion protection requirements were required to be met by 

December 22, 1998. 

The leak detection requirements for existing UST are similar to the requirements for new 

UST. Existing UST can use any of the six monthly monitoring methods as described for new 

UST. Spill and overfill requirements are the same for existing and new UST. Existing UST 

must also meet the corrosion protection requirements. If the existing tank does not currently 

meet the corrosion requirements specified for new UST, the existing UST must be modified. If 

the existing UST is made of steel, one of following methods must be chosen to add corrosion 

protection: (1) add cathodic protection, (2) add interior lining to the UST, i.e., non-corrodible 

material, or (3) combine cathodic protection and interior lining. The existing UST piping that is 

made of steel must also have cathodic protection. 

– SIP Credits Associated with Preventing UST Leaks 

Currently, the federal UST regulation requires a GDF to pick one of six monthly 

monitoring methods for identifying UST leaks (described above), or as an alternative to the 

monthly monitoring methods, a new UST may combine inventory control with tank tightness 

testing for the first ten years after the installation of the UST. While these monitoring 

requirements are mostly in place to detect liquid leaks from UST, some of the monitoring 

methods may also detect vapor leaks, for example, the tank tightness requirements. In addition, 

periodic pressure testing of the UST such as static pressure tests or pressure decay tests will 

confirm that there are no vapor leaks from the tank and fittings. We believe that SIP credits may 

be warranted for areas that require GDF to perform a combination of monitoring methods to 

monitor for UST liquid and vapor leaks. A GDF utilizing more than one monitoring method 

would have a back-up method in the event one monitoring method failed to detect a leak. SIP 

credits may also be warranted for areas that require more frequent monitoring than monthly 

monitoring. 
DRAFT 2-07-06 

21

IV. Stage II Discussion Meetings with Stakeholders and Vendors 

During Stage II data collection, we met one-on-one with HERTZ, Alliance of 

Automobile Manufacturers (AAM), ARID Technologies, Inc. (ARID), Vapor Systems 

Technologies, Inc. (VST), Healy Systems, Inc. (Healy), EMCO Wheaton, and the American 

Petroleum Institute (API). The information discussed and/or data received from these meetings 

are summarized below. 

A. Hertz Meeting Summary 

At the request of Hertz Rent-a-Car (Hertz), we met to discuss a waiver from Stage II 

VRS requirements for existing and new rental car facilities. Hertz currently maintains a vehicle 

fleet where approximately 97 percent of the vehicles have ORVR equipment. Hertz believes that 

because their vehicle fleet is almost entirely comprised of vehicles with ORVR equipment and 

because maintaining Stage II VRS is redundant, removal of Stage II VRS at their facilities would 

not result in an increase in VOC emissions. Although we cannot provide a direct waiver from 

Stage II VRS requirements to Hertz, we have discussed providing a memorandum to States and 

Regions that would support the granting of a waiver of Stage II VRS by a State. 

In order to obtain emissions data to support development of such a memorandum, we 

have discussed with Hertz a monitoring schedule for emissions points at GDF under several 

scenarios. The objectives for such monitoring are to: (1) demonstrate that VOC emissions would 

not increase if Stage II VRS are removed at existing Hertz airport GDF facilities, (2) demonstrate 

that VOC emissions would not increase if Stage II VRS are not installed at newly constructed 

Hertz airport GDF facilities, and (3) demonstrate that VOC emissions reductions from refueling 

a high percentage of ORVR-equipped vehicles are at least equivalent to emissions reductions 

obtained from a Stage II VRS. 

B. Alliance of Automobile Manufacturers (AAM) Meeting Summary 

Also, at the request of AAM we met to discuss a waiver from Stage II VRS requirements 

at automobile manufacturing facilities. AAM believes that because almost all of the new 

vehicles being refueled at manufacturing facilities have ORVR equipment and because 

maintaining Stage II VRS is redundant, removal of Stage II VRS at their manufacturing facilities 

would not result in an increase in VOC emissions. Again, we informed them that although we 

cannot provide a direct waiver from Stage II VRS requirements to automobile manufacturers, we 

have discussed providing a memorandum to States and Regions that would support the granting 

of a waiver by a State. Although such a waiver request would be very similar to the rental car 

agency waiver described above, there are several key differences in the refueling operations for 

the automobile manufacturers, such as: (1) there are no vapors in the vehicle gasoline tanks 

before they are fueled for the first time, so there are no vapors to be expelled from the vehicle 

tank (also called the “green tank effect”) and (2) the line from the gasoline dispenser to the UST 

may be several miles long, which may cause some additional emissions due to the expansive 

piping necessary to move the gasoline to the dispensing area. The automobile manufacturers 

have submitted some emissions test data monitoring these conditions. These data are 

summarized in Section VI. 
DRAFT 2-07-06 

22

C. ARID Technologies Meeting Summary 

We met with representatives of ARID Technologies, manufacturers of add-on APCD for 

UST vents. The APCD is a membrane technology (called PERMEATOR) that prevents UST 

venting of gasoline vapors. ARID claims the technology can be used with balance Stage II VRS 

and vacuum assist VRS. ARID believes the technology allows for improved UST vapor 

recovery efficiency during UST breathing and emptying; the technology has the potential to 

recover gasoline product that would otherwise be emitted to the atmosphere as vapor. 

ARID believes there is an increase in emissions that results from the combined use of 

vacuum assist Stage II VRS and ORVR. ARID also maintains that counting UST emissions as 

either fugitive or vent emissions is largely academic. The important point is that an excess vapor 

generation rate is present within the UST system. The excess vapor volume will result in an 

observed pressure increase within the UST. A relatively “tighter” system will yield higher UST 

vent emissions (ARID includes emptying, breathing, and incompatibility excess emissions) and a 

relatively leaky system will yield higher fugitive emissions. In general, if an UST add-on APCD 

is employed to reduce the overall storage tank pressure while at the same time capturing and 

recovering UST vent emissions, the driving force for fugitive emissions is greatly reduced, and 

both the fugitive and UST vent emissions are significantly reduced. 

D. Vapor Systems Technologies, Inc. (VST) Meeting Summary 

We met with representatives of VST, manufacturers of another add-on APCD for the 

UST vent. VST’s product, a membrane processor that reduces fugitive emissions, is undergoing 

CARB testing to determine if it is compatible with refueling ORVR-equipped vehicles. VST has 

3 test sites in California and is working to establish additional test sites in other regions in the 

U.S. VST believes that its monitoring data show: (1) most, if not all, positive tank pressure 

fugitive emissions to the atmosphere are from leaking UST systems, (2) the increase in ORVR 

vehicle penetration is causing increased fugitive emissions when used with vacuum assist Stage 

II VRS, and (3) VST’s new technologies provide the ability to use ORVR and Stage II VRS 

systems simultaneously while reducing UST systems pressures and eliminating fugitive vapor 

emissions. 

VST believes the fugitive vapor emissions at GDF are more severe than previously 

considered. VST believes that the growing rate of ORVR equipment in the vehicle population is 

contributing to an increase in fugitive vapor emissions. VST believes that UST systems have a 

high leak rate, resulting in increased fugitive emissions, and the UST systems require a high 

level of maintenance to remain tight. 

E. Healy Systems, Inc. (Healy) Meeting Summary 

Healy believes that the assumption that ORVR fleet penetration at some point will make 

Stage II VRS redundant is not accurate. Healy believes that 20 percent of gasoline dispensed in 

the foreseeable future will fuel non-ORVR equipped vehicles and other motor driven units. If 

Stage II VRS equipment is removed, then 100 percent of the refueling vapor emissions 

associated with non-ORVR equipped vehicles and other motor driven units will be emitted to the 

atmosphere. Healy also maintains that the source of emissions at GDF is positive pressure build-
DRAFT 2-07-06 

23

up in the ullage space of the UST and that the problem is associated with the design of Stage II 

vacuum assist VRS. Healy suggests that fugitive leaks are in the magnitude of 1 gallon per 

minute. Healy manufactures an UST add-on APCD, the Clean Air Separator (or bladder tank), 

that acts as a pressure management system. Any excess vapors from the UST vent due to 

pressurization are routed to the bladder tank and are contained rather than emitted to the 

atmosphere. These vapors may be returned/pulled back into the UST from the bladder through 

the UST vent when the UST pressure drops below -8.0 inches of water column (in. w.c.). The 

bladder collapses as the contained vapors are returned to the UST. 

F. EMCO Wheaton Retail Meeting Summary 

EMCO Wheaton manufactures various gas dispensing nozzles, including a dripless 

nozzle, P/V valves, Stage I fittings for UST, manhole covers, and other equipment. EMCO 

Wheaton believes that nozzles are not being replaced frequently enough; many nozzles at GDF 

deteriorate to the point where the nozzle can no longer shut itself off during vehicle refueling. 

EMCO Wheaton referenced a study conducted in Southern California that showed, on average, 

that nozzles are approximately 18 months old. EMCO Wheaton sells a standard nozzle for 

approximately $20, while a Stage II VRS nozzle costs approximately $110. One of EMCO 

Wheaton’s test sites in California with a balance Stage II VRS showed that the P/V valve never 

opened and that the tank pressure never exceeded 3 in. w.c. over a one-year period. EMCO 

Wheaton also stated that new UST are structurally sound and are extremely tight, and as a result, 

vapor leaks are not likely to occur. Vapor leaks may occur, however, around the tank’s fittings. 

Tank inspections aid in the ability to keep the UST tight and are often performed every 6 months 

in California. EMCO Wheaton believes underground contamination is caused by residual 

contamination and not new leaks and that drips from GDF may also be contributing to 

groundwater pollution. In summary, EMCO Wheaton believes that (1) balance Stage II VRS 

should be retained because these systems are already ORVR compatible, and very little expense 

is required to convert a vacuum assist VRS to a balance VRS, (2) GDF should be inspected 

frequently, (3) UST vents need to be tested, (4) CARB’s EVR program is too stringent and 

expensive and does not result in corresponding emissions reductions, (5) the widespread use 

definition should retain Stage II VRS for as long as possible, and (6) in-station diagnostics (ISD) 

are inexpensive and effective. 

G. American Petroleum Institute (API) Meeting Summary 

API began the discussions with a general presentation of the Stage II VRS, widespread 

use, and ORVR/Stage II VRS incompatibility issues. A description of widespread use studies 

conducted by API followed. API also described a study conducted by the University of 

Tennessee on the costs associated with operating and maintaining Stage VRS. During a 

discussion of in-use control efficiency claimed by State and local air pollution control programs 

(States), API indicated that States claim 77 percent, while EPA said that some States claim up to 

90 percent. MOBILE6, the EPA model for estimating emissions from mobile sources, applies a 

98 percent control efficiency for the fill-pipe refueling emissions. A discussion of what CARB is 

requiring for most California GDF followed. Enhanced Vapor Recovery (EVR) and in-station 

diagnostics programs were discussed. API said that it would cost each station about $30,000 to 

comply with the EVR program and that few, in some cases none, equipment vendors had 

developed equipment to comply with CARB’s EVR requirements. 
DRAFT 2-07-06 

24

The key discussion concerned the differences between CARB’s and API’s 

incompatibility excess emissions (IEE) that occur when refueling a car. API disagreed with the 

way CARB conducted the tests and with the way CARB interpreted the results of their testing. 

Further, API explained how their testing was more realistic and showed the IEE to be less than 

half of CARB’s IEE levels. CARB estimated IEE to be 2.5 to 4.5 tons per day for the entire 

state. Discussions of emissions from USTs followed and API disagreed with the way that CARB 

estimated the pressure-related fugitive emissions. 

API described a collaborative effort by CARB and the Western States Petroleum 

Association (WSPA) to collect more information about pressure-related emissions. The results 

of this project may be very informative for any decisions EPA would make. However, it is our 

understanding that this project has not been started and may have been cancelled. API also 

described some other IEE, UST, and widespread use testing they have been doing in an Arizona 

laboratory. 

A discussion of the issues paper (see aforementioned references) ensued and EPA 

indicated that if a definition requires calculation of emissions, EPA would probably use 

MOBILE6. EPA also thought that there may be enough information to quantify IEE. API 

disagreed and added that CARB does not believe there are enough data to quantify IEE. This 

discussion led to a discussion of incompatibility emissions factors and their validity. 

There was some final discussion of the industry in general and whether “majors” or 

“independents” owned the gas stations. Independents own most of the GDFs. There was also 

some discussion of potential SIP credit ideas, especially where States may add or retain Stage II 

VRS after the widespread use date. 

V. Public Meeting – September 2004 

On September 20, 2004, EPA held a public meeting to provide stakeholders and other 

interested parties the opportunity to present data or views concerning Stage II VRS, widespread 

use, or other pertinent Stage II issues. Approximately 30 non-EPA people attended the meeting 

in Research Triangle Park, along with 10 EPA staff and 12 participants by phone, including 2 

EPA regional staff and a representative from the California Air Resources Board. Thirteen 

representatives of refining trade associations, marketing trade associations, States, equipment 

vendors, and gasoline station inspectors made presentations at this meeting. EPA asked 

clarifying questions during the presentations but did not respond to specific or direct questions 

raised during the meeting. 

At the conclusion of the meeting, EPA encouraged stakeholders to provide their 

presentations either electronically or in hard copy, as well as to provide any data pertaining to 

Stage II emissions or other pertinent data. EPA posted papers, presentations, and data on an 

EPA website accessible to the public (http://www.epa.gov/ttn/naaqs/ozone/ozonetech/stage2/). 

EPA also said that it would not respond to individual comments from stakeholders but would 

respond generally in a rule or policy regarding Stage II. 
DRAFT 2-07-06 

25

A. Comments from the Public Meeting and on EPA’s Issues Paper 

Twenty-two representatives of refining trade associations, marketing trade associations, 

States, equipment vendors, and gasoline station inspectors submitted comments. A list of the 

stakeholders who submitted comments and a general overview of the comments are presented 

below. 

Table 1. List of Stakeholder Commenters 

Entity Contact(s) Comment Reference

NESCAUM Ken Colburn Executive Director, 

(Lisa Rector) 

Letter dated September 30, 2004 

www.epa.gov/ttn/naaqs/ozone/ozonetech/stag

e2/nescaum_09-30-04.doc

Connecticut Department of 

Environmental Protection 

(Connecticut DEP) 

Chris James, Director, Planning 

& Standards, 

(Ariel Garcia, Debbie Tedford) 

Letter dated September 30, 2004 

www.epa.gov/ttn/naaqs/ozone/ozonetech/stag

e2/state_of_conn_9-30-04.pdf

New Jersey Department of 

Environmental Protection 

(NJDEP) 

Judith Rand Letter dated September 29, 2004 

www.epa.gov/ttn/naaqs/ozone/ozonetech/stag

e2/state_of_new_jersey_09-29-04.doc

Commonwealth of Virginia 

(Virginia) 

James Ponticello Letter dated September 30, 2004 

www.epa.gov/ttn/naaqs/ozone/ozonetech/stag

e2/comonwealth_of_va_9-30-04.pdf

California Air Resources 

Board (CARB) 

Cindy Castronovo Letter dated October 4, 2004 

www.epa.gov/ttn/naaqs/ozone/ozonetech/stag

e2/calif_air_resources_board_10-4-04.pdf

Texas Commission on 

Environmental Quality 

(TCEQ) 

David Schanbacher, Chief 

Engineer, 

(Kim Herndon, Eddie Mack, 

Jason Harris) 

Letter dated September 30, 2004 

www.epa.gov/ttn/naaqs/ozone/ozonetech/stag

e2/state_of_texas_09-30-04.wpd

Wisconsin Department of 

Natural Resources 

(Wisconsin DNR) 

Lloyd Eagan, Director, Bureau 

of Air Management, (Ralph 

Patterson) 

Letter dated September 29, 2004 

www.epa.gov/ttn/naaqs/ozone/ozonetech/stag

e2/state_of_wisconsin_09_30_04.pdf

Ohio Environmental 

Protection Agency 

(Ohio EPA) 

Bill Juris, Compliance and 

Enforcement 

Letter received September 30, 2004 

www.epa.gov/ttn/naaqs/ozone/ozonetech/stag

e2/state_of_ohio_9-30-04.doc

Missouri Department of 

Natural Resources (Missouri 

DNR) 

Leanne Tippett Mosby, Director 

(Bud Pratt) 

Letter dated September 15, 2004 

www.epa.gov/ttn/naaqs/ozone/ozonetech/stag

e2/state_of_missouri_9-15-04.pdf

Collier Shannon Scott, 

Counsel to National 

Association of Convenience 

Stores (NACS) and Society 

of Independent Gasoline 

Marketers of America 

(SIGMA) 

R. Timothy Columbus, Gregory 

Scott, Joseph Green 

Letter dated September 30, 2004 

www.epa.gov/ttn/naaqs/ozone/ozonetech/stag

e2/nacs_sigma_09-30-04.pdf

BP US Convenience 

Operations 

(BP) 

James S. White, Regulatory 

Affairs 

Letter received September 28, 2004 

www.epa.gov/ttn/naaqs/ozone/ozonetech/stag

e2/bp_us_convenience_operations_09-30-

04.doc
DRAFT 2-07-06 

26

Entity Contact(s) Comment Reference

Veeder-Root Kent Reid, Director of Strategic 

Development 

Letter dated September 14, 2004 

www.epa.gov/ttn/naaqs/ozone/ozonetech/stag

e2/veeder_root_%209-15-04.doc

Healy Systems, Inc. 

(Healy) 

James Healy, President Letter dated September 15, 2004 

www.epa.gov/ttn/naaqs/ozone/ozonetech/stag

e2/healy_systems_9-15-04.pdf

Letter dated September 30, 2004 

www.epa.gov/ttn/naaqs/ozone/ozonetech/stag

e2/healy_systems_9-30-04.pdf

EMCO Wheaton Retail 

(EMCO) 

Jim Lawrence, (Ken Turcotte) Letter dated September 29, 2004 

www.epa.gov/ttn/naaqs/ozone/ozonetech/stag

e2/emco_wheaton_09-30-04.doc

Letter Attachment 1 

www.epa.gov/ttn/naaqs/ozone/ozonetech/stag

e2/emco_wheaton_attachment_1_09-30-

04.pdf

Letter Attachment 2 

www.epa.gov/ttn/naaqs/ozone/ozonetech/stag

e2/emco_wheaton_attachment_2_09-30-

04.pdf

Vapor Systems 

Technologies, Inc. 

(VST) 

Glenn K. Walker, President, 

(Scott Brown) 

Letter dated September 30, 2004 

www.epa.gov/ttn/naaqs/ozone/ozonetech/stag

e2/vapor_systems_technology_09-30-04.pdf

American Petroleum 

Institute (API), NACS, 

Petroleum Marketers 

Association of America 

(PMAA), SIGMA 

Prentiss Searles, representing 44 

state and regional trade 

associations, 8000 independent 

petroleum marketers, 1,700 

retail member companies 

(100,000 stores employing 1.4 

million workers), 250 

independent fuel marketers, and 

28,000 retail outlets employing 

more than 270,000 workers. 

Letter dated September 30, 2004 

www.epa.gov/ttn/naaqs/ozone/ozonetech/stag

e2/nacs_sigma_pmaa_api_09-30-04.pdf

Attachment (Letter to API from Sonoma 

Technology , Inc. [STI]) 

www.epa.gov/ttn/naaqs/ozone/ozonetech/stag

e2/nacs_sigma_pmaa_api_attachment_09-30-

04.pdf

Costco Wholesale, Inc. 

(Costco) 

Tim Hurlocker, Director of 

Gasoline Operations 

Letter received September 30, 2004 

www.epa.gov/ttn/naaqs/ozone/ozonetech/stag

e2/costco_wholesale_09-30-04.doc

Husky Corporation (Husky) Art Fink, VP Engineering Letter received September 28, 2004 

www.epa.gov/ttn/naaqs/ozone/ozonetech/stag

e2/husky_09-28-04.doc

Letter dated August 31, 2004 

www.epa.gov/ttn/naaqs/ozone/ozonetech/stag

e2/husky_8-31-04.pdf

Crompco Corporation 

(Crompco) 

Edward Kubinsky Jr. Letter received September 23, 2004 

www.epa.gov/ttn/naaqs/ozone/ozonetech/stag

e2/crompco_09-23-04.doc

Frank & Gramling, Counsel 

to Florida Petroleum 

Marketers Association 

(FPMA) 

Robert Fingar Letter dated September 27, 2004 

www.epa.gov/ttn/naaqs/ozone/ozonetech/stag

e2/fpma_%2009-27-04.doc
DRAFT 2-07-06 

27

Entity Contact(s) Comment Reference

ARID Technologies, Inc. 

(ARID) 

Tedmund Tiberi Letter dated September 28, 2004 

www.epa.gov/ttn/naaqs/ozone/ozonetech/stag

e2/arid_technologies_9-30-04.pdf

Remote Sensing Air, Inc. 

(RSA) 

Judith Zwicker Letter dated September 10, 2004 

www.epa.gov/ttn/naaqs/ozone/ozonetech/stag

e2/remote_sensing_air_09-10-04.doc

B. Stage II Vapor Recovery Systems – Balance vs. Vacuum Assist 

As discussed earlier in this paper, the two most common types of Stage II VRS are 

balance and vacuum assist. 

1. Comment Overview 

Two stakeholders indicated that they prefer the balance VRS over the vacuum assist 

VRS. Other stakeholders indicated that they have concerns regarding the effectiveness of 

vacuum assist systems, mainly due to the incompatibility issues associated with vacuum assist 

VRS and ORVR, which is discussed further in Section V.C. One stakeholder commented that 

they had no choice but to use a vacuum assist VRS due to their operational model design (single 

direction traffic through the GDF requires longer hoses to fuel from either side of the vehicle). 

The Missouri DNR stated that its Air Pollution Control Program (APCP) determined that 

a Stage II vacuum assist VRS does not perform as well as a balance VRS. The APCP was able 

to make this determination from inspector observations. The APCP specifically observed excess 

emissions [not related to incompatibility excess emissions] from the P/V valves or excess 

emissions from the nozzle interface for vacuum assist systems. The inspectors also observed 

problems with vacuum assist VRS vapor processors (i.e., UST vent add-on APCD, or 

processors) and perpetual maintenance issues. In contrast, the APCP system testing performed 

on balance VRS indicated that the balance system is more reliable and more economical to 

maintain. Missouri DNR suggested that EPA closely consider requiring the conversion of 

vacuum assist Stage II VRS to balance Stage II VRS. 

A representative from RSA asked the question, “Does it make sense to allow the 

continued use of Assist VRS with their higher emissions than Balance VRS even without the 

ORVR incompatibility...” issue? RSA suggested that balance Stage II VRS are less expensive 

and more efficient than vacuum assist VRS and that Missouri has proven that the conversion of 

most vacuum assist VRS to balance VRS is easy and relatively inexpensive. RSA also stated 

that UST vent emptying and breathing emissions are significant for vacuum assist systems and 

that Missouri DNR and CARB have shown that these emissions are much less significant for 

balance systems that use the natural pressure balance of the system to keep pressures around an 

average of -0.5 in. w.c. Fugitive emissions are also much less significant for a balance VRS 

because of the system’s relative steady low pressures. RSA stated that system pressures greater 

than 2 in.w.c. for any significant amount of time causes the release of pressure-related fugitives 

through nozzle check valves, breakaways, etc.; vacuum assist VRS are more likely to reach these 

pressures than balance VRS. 
DRAFT 2-07-06 

28

2. Discussion and Recommendation 

As mentioned above, there are basically two types of Stage II VRS – balance and vacuum 

assist. The balance VRS is a relatively benign system that relies on a tight seal between the 

vehicle being refueled and the faceplate of the nozzle. During refueling, a slight vacuum occurs 

in the UST that helps pull the vapors into the UST vapor space. These VRS are relatively 

inexpensive and easy to maintain. Another feature of the balance Stage II VRS is that the entire 

system (including the UST) typically does not result in pressurization (and stays at mostly 

negative pressure), which may prevent fugitive leaks. Conversely, vacuum assist VRS 

dispensing equipment costs up to $40,000 and cost approximately $4,100 to maintain.4537 

Vacuum assist Stage II VRS may require an UST pressurization system (i.e., an UST add-on 

APCD or UST processor) to maintain a negative pressure. 

UST pressure data indicates, for the most part, that balance VRS are either not 

pressurized or less pressurized than the vacuum assist VRS. We believe that low or no 

pressurization, generally, would result in fewer or no fugitive emissions throughout the system. 

However, we believe that it would be difficult to defend requiring only balance VRS if: (1) Stage 

II VRS requirements were retained, or (2) EPA provided SIP credits for State or local authorities 

that choose to retain Stage II VRS. One UST add-on APCD, the ARID Permeator, was tested at 

a GDF with vacuum assist Stage II VRS to provide information about its efficiency for 

pressurized systems. This testing included emissions measurement of the UST emissions and 

showed greater than 99 percent reduction in UST vent emissions over uncontrolled levels (with a 

P/V valve and with an add-on APCD). This same add-on APCD is to be tested at a new GDF 

with no Stage II VRS; this test will provide information about its efficiency for non-pressurized 

systems (no P/V and with an add-on APCD). 

We do not recommend a policy dictating the type of Stage II VRS to be used. We do 

recommend a policy or regulation requiring GDFs to completely dismantle or disable the VRS in 

a way that will not exacerbate fugitive leaks. 

C. On-Board Refueling Vapor Recovery (ORVR) Control Efficiency 

ORVR is a fairly new technology (ORVR installation commenced in model year 1998 

vehicles) that collects the gasoline vapor displaced from the vehicle fuel tank during filling; the 

gasoline vapors are adsorbed in a canister, and sometime afterwards, are released to the engine. 

ORVR controls are expected to achieve from 95 to 98 percent reduction of the vehicle refueling 

emissions. 

 

45Letter from P. Searles, API, to L. Rector, NESCAUM. ORVR Widespread Use. March 9, 2005. 
DRAFT 2-07-06 

29

Table 2. Stage II VRS Comment Summary 

Stakeholder Comment Summary Comment Details

Missouri DNR Missouri DNR stated that Stage II vacuum 

assist VRS are more problematic than 

balance VRS. Missouri DNR contended 

that balance systems are more effective and 

easier to maintain. 

- Missouri DNR’s APCP has observed from a 

vacuum assist system excess emissions from 

P/V valves or excess emissions from the nozzle 

interface. There are currently no Stage II 

vacuum assist VRS in Missouri now. 

- Missouri DNR stated, “It seems surprising that 

VA systems have been used at all since they are 

more expensive to purchase, install and 

maintain than balance systems and have a lower 

efficiency than balance systems.” 

RSA RSA indicated that balance VRS are more 

effective than vacuum assist VRS. RSA 

stated that higher UST pressures lead to 

more emptying and breathing emissions and 

fugitive emissions. Vacuum assist VRS 

were more likely to reach higher pressures, 

which lead to emissions. 

Costco Costco stated that they typically do not use 

balance VRS because their high-volume 

operational model requires extra-long 

hoses. 

Costco stated that Stage II balance VRS do not 

work with Costco’s operational model due to 

the need for extra-long hoses. CARB has only 

approved a short (9 foot) balance hose. 

1. Comment Overview 

Concerns were expressed regarding the control efficiency of ORVR canisters and the 

long-term control efficiency these canisters will continue to achieve. Eight stakeholders and one 

equipment vendor expressed concern regarding the effectiveness of ORVR canisters over the life 

of the vehicle. Another stakeholder suggested that there was sufficient data to support the longterm use of ORVR. 

NESCAUM and the Connecticut DEP stated that before determining when widespread 

use occurs, EPA should determine the effectiveness of ORVR canisters over the life of the 

vehicle. NESCAUM is concerned about the effectiveness of the OBD systems that indicate 

ORVR malfunctions; these systems should be tested and verified by EPA before any decisions 

are made about widespread use. The Wisconsin DNR, Missouri DNR, and CARB indicated that 

they are concerned that ORVR control efficiency will degrade over time. Both NESCAUM and 

Healy stated that EPA should test high mileage ORVR-equipped vehicles to determine the 

ORVR efficiency over time. TCEQ has requested that EPA provide to States technical 

documentation demonstrating the ORVR actual in-use efficiency of 98 percent, as well as 

information detailing how EPA plans to ensure continued compliance of the ORVR control 

efficiency. 

The Wisconsin DNR asked if ORVR compatible Stage II VRS could be viewed as a 

backup for those ORVR systems that fail to operate correctly. The Ohio EPA stated that the 

effectiveness of ORVR with and without vehicle inspection and maintenance programs should be 

addressed. 
DRAFT 2-07-06 

30

API suggested that solid testing methodologies are used to demonstrate ORVR 

effectiveness. NACS and SIGMA stated that they believe sufficient data already exists to 

support the long-term use of ORVR. 

2. Discussion and Recommendation 

We believe that ORVR control efficiency can achieve from 95 to 98 percent reduction of 

the vehicle refueling emissions based on ORVR canister design. There are currently no data 

confirming the long-term control efficiency, per se, of ORVR canisters, however, EPA does have 

data that indicate that ORVR canisters are meeting their emissions limit of 0.2 grams per gallon 

(g/gal). These data show some difference in performance for high and low mileage vehicles but 

additional testing is planned. EPA has also been actively testing the performance of OBD 

systems, the OBD evaporative emissions monitor, and the ORVR system integrity checks. 

Vehicles are equipped with an on-board diagnostics (OBD) system that, in addition to a number 

of other functions, checks the integrity of the vehicle’s evaporative system, stores diagnostic 

trouble codes (DTC), and alerts the operator/driver with a malfunction indicator light (MIL) on 

the dashboard of the vehicle that a repair may be needed. The OBD is designed to identify 

malfunctioning emissions control components on the vehicle before emissions standards are 

exceeded. Studies have shown that OBD systems identify deteriorated or broken components or 

systems that lead to higher emissions. 

One of the OBD functions is to monitor the ORVR system integrity by periodically 

checking the evaporative system pressure as well as the ORVR canister purge function. If the 

OBD detects a problem with the ORVR system, a warning light (a MIL) indicating an engineproblem comes on so that the vehicle operator knows to seek service and repair. ORVR system 

failures detected by the OBD fall into two categories: (1) failure of the purge function, and (2) 

loss of system integrity. The purge diagnostic checks to see that a controlled volume of air is 

drawn through the canister. The air desorbs hydrocarbons from the canister carbon and then 

carries them to the engine to be burned. If the air purge is not functioning, the carbon in the 

ORVR canister becomes saturated and cannot hold any additional refueling vapors. The OBD 

also checks to identify any leaks occurring in the hoses and connections that route the gas vapors 

to the canister and to the engine, as well as the mechanical integrity of the tank and fill-neck. 

The hoses and connections of the ORVR system must be leak proof for the ORVR control 

system to work.4638

From April 1999 to May 2000, EPA conducted a 30-vehicle study to evaluate the 

effectiveness of OBD evaporative emissions monitors in identifying in-use vehicles (model years 

1996 through 2000) with excess evaporative emissions. In this study, 22 of 25 OBD evaporative 

emissions monitors registered DTCs when failure conditions were induced, suggesting that OBD 

evaporative emissions monitors work satisfactorily. Five vehicles were tested with small leaks; 3 

of the 5 vehicles were calibrated to meet the 0.040 in. OBD leak standard but were tested with a 

 

46 The Long-Term Durability of Onboard Vehicle Vapor Recovery (ORVR) Control Systems, Draft. Prepared for 

API by Harold Haskew & Associates, Inc. February 2005. 
DRAFT 2-07-06 

31

smaller 0.020 in leak and illuminated DTCs. This suggests that some OBD systems are quite 

robust and have leak detection capability well below the minimum federal requirement.4739

Two other major programs concerning OBD performance have been or are being 

conducted: (1) EPA has conducted a high-mileage OBD study on model year 1996 through 1999 

vehicles with greater than 100,000 miles, and (2) EPA has begun to receive data from 

automobile manufacturers on OBD performance in calendar year 2005 on model year 2001 highmileage (50,000+) vehicles and model year 2004 low-mileage (10,000+) vehicles as part of the 

In-Use Verification Program (IUVP).4840 This program includes approximately 2000 FTP 

emissions data tests per year and OBD information (MIL illumination and DTC). In conjunction 

with the manufacturer testing, EPA will also conduct confirmatory tests on approximately 150 

vehicles per year to verify the results of the manufacturer in-use testing. The data from these two 

programs should provide sufficient information to evaluate and confirm that OBD systems are 

working effectively and increase confidence in their use. 

Some preliminary data from EPA’s IUVP program are provided in section VI.B. These 

data indicate that the majority of OBD systems perform well and that the majority of ORVR 

canisters are performing at or above the required emissions standard. Of 151 tests on the ORVR 

canisters, 91 percent reduced refueling emissions to 0.2 g/gal or less. There were some 

differences in low mileage vehicles versus high mileage vehicles (with a larger percent of the 

low mileage vehicles passing the emissions limit). 

Based on evaporative system testing, of which ORVR is one part, the system does appear 

to remain intact and operate properly, with a low failure rate. The OBD evaporative emissions 

check has been found to be a suitable replacement for functional evaporative emission I/M tests. 

Based on testing of ORVR canisters that are in-use on vehicles, these canisters appear to 

continue controlling refueling emissions after several years of operation. See Section VI.B for 

additional data. Given the preliminary results from these studies, we are comfortable with the 

long-term functionality of the vehicle evaporative system and the ORVR canister controls. EPA 

is continuing to evaluate these systems and collect the testing data from automobile 

manufacturers and conduct testing itself. 

An idea was suggested that with retention of Stage II VRS on GDF, even retention of 

ORVR-compatible VRS, that the Stage II VRS could possibly be viewed as a backup for those 

ORVR systems that fail. API submitted a paper that indicated that the design of the fillpipe on 

an ORVR-equipped vehicle has a seal (either liquid or mechanical) that prevents vapors from 

exiting to the atmosphere.4941 The seal is designed to ensure that vapors from the vehicle gasoline 

tank are routed to the ORVR canister and do not escape through the fillpipe. With such a design, 

a Stage II VRS is not likely to control refueling emissions from failing ORVR vehicles, even 

with an “ORVR-compatible” system at the GDF. 

 

47 Effectivness of OBD II Evaporative Emissions Monitors – 30 Vehicle Study. U.S. Environmental Protection 

Agency. EPA Publication No. EPA420-R-00-018. October 2000. 

48 On-Board Diagnostics (OBD) Policy Workgroup: Findings and Recommendations, by the Mobile Source 

Technical Review Subcommittee, Clean Air Act Advisory Committee. November 2002. p. 11 and 16. 

49 The Long-Term Durability of Onboard Vehicle Vapor Recovery (ORVR) Control Systems. Prepared for 

American Petroleum Institute (API) by H. Haskew, Harold Haskew and Associates. May 27, 2005. 
DRAFT 2-07-06 

32

Table 3. On-board Refueling Vapor Recovery (ORVR) Comment Summary 

Stakeholder Comment Summary Comment Details

NESCAUM NESCAUM indicated that they are 

concerned about the effectiveness 

of ORVR canisters. NESCAUM 

suggested that EPA review 

relevant test data to ensure that a 

reasonable efficiency factor is 

attributed to ORVR. 

NESCAUM suggested the following: 

1. A need to provide support and oversight of the 

automotive industry so as to ensure failing 

ORVR systems are properly maintained. 

2. A need to understand the types of malfunctions 

that a vehicle’s OBD can detect. 

3. EPA should test high mileage vehicles and those 

vehicles that have been in service for a number 

of years to determine the efficiency of the ORVR 

system over time. 

4. Develop a system to track ORVR system 

problems. The system should resemble the 

procedures used to verify proper operation of 

Stage II VRS. 

Connecticut DEP The Connecticut DEP stated that 

the phase out of Stage II should not 

occur until ORVR effectiveness 

has been determined over the 

lifespan of the ORVR canister. 

Connecticut DEP believes the possibility of ORVR 

system failures exist and if such failures were to 

occur after Stage II VRS removal, refueling vapor 

emissions would be too serious of an occurrence to 

risk. 

Wisconsin DNR Wisconsin DNR asked, ‘Could 

ORVR-compatible Stage II 

systems be viewed as “insurance” 

or back-up for those ORVR 

systems that fail to operate 

correctly or efficiently?’ 

Wisconsin DNR also stated their need to know 

what EPA’s expectations are in terms of in-use 

efficiency of ORVR, asked whether there will be 

an ORVR degradation factor, and what is the 

technical basis for these expectations. 

Ohio EPA The Ohio EPA indicated that I/M 

issues related to ORVR should be 

addressed. 

“The effectiveness of ORVR with and without a 

motor vehicle inspection and maintenance 

program.” 

Missouri DNR Missouri DNR indicated that 

ORVR carbon canisters eventually 

break down. 

Missouri DNR stated that there is not sufficient 

data to know with any level of confidence that 

ORVR vehicles will maintain their initial 

efficiency; older vehicles will eventually most 

likely need Stage II VRS to control refueling 

emissions. 

TCEQ TCEQ stated that the Issues paper 

did not cite any studies that 

determines the actual in-use 

control efficiency of ORVR 

systems. 

TCEQ suggested that EPA “...provide the states 

with technical documentation demonstrating the 

stated ORVR IUE of 98 percent as well as 

information detailing how EPA plans to ensure that 

automobiles continue to comply with this standard. 

Texas believes that EPA should analyze IUE and 

provide results of their analysis to the states.” 

CARB CARB stated that API’s study and 

the Issues Paper did not consider 

the possible degradation of the 

ORVR efficiency of 98 percent. 

Healy Healy commented that the in-use 

control efficiency of ORVR was 

not addressed in the Issues Paper. 

Healy recommended that EPA evaluate a selection 

of 1998 ORVR-equipped vehicles with high 

mileage using SHED test methods or equivalent 

test methods to determine in-use control efficiency. 
DRAFT 2-07-06 

33

Stakeholder Comment Summary Comment Details

API API stated that the effectiveness of 

ORVR has been demonstrated 

using solid testing methodologies. 

API stated, “The effectiveness of ORVR is 

required to be demonstrated using solid testing 

methodologies (Sealed Housing for Evaporative 

Determinations) in new vehicles and has also been 

confirmed in tests conducted using California 

testing methodologies on in-use vehicles at actual 

gasoline dispensing facilities (GDFs), without any 

need for regulatory agencies to have to hire 

personnel to inspect the systems on a regular 

basis.” 

NACS and SIGMA NACS and SIGMA referenced inuse evaporative system testing data 

for ORVR-equipped vehicles 

submitted by the North Carolina 

Petroleum Marketers Association 

to EPA. 

NACS and SIGMA stated that the evaporative test 

data confirmed the performance of ORVR as an 

effective control technology for refueling 

emissions; these data supported the assumptions 

that underpin the policy choice by Congress to 

utilize ORVR for the long-term. 

D. ORVR and Stage II VRS Compatibility Issues 

When an ORVR-equipped vehicle refuels at GDF with Stage II VRS, the amount and 

composition of the vapor returned to the UST by the Stage II VRS controls can be adversely 

impacted. An increase in the amount of air (in lieu of gasoline vapor) returned to the vapor 

space of the UST will lead to gasoline evaporation, or vapor growth, in the UST and lead to 

excess emissions from the UST in the form of fugitives and vent emissions. A larger amount of 

air is returned to the UST vapor space for some vacuum assist Stage II VRS when refueling 

vehicles with ORVR controls, and therefore, the excess emissions are greater for some vacuum 

assist systems. 

1. Comment Overview 

Eight stakeholders and two equipment vendors believe that there are incompatibility 

issues associated with vacuum assist Stage II and ORVR. Two stakeholders believe there are 

incompatibility issues but these issues become negligible when taking into account that ORVR 

reduces vehicle fillpipe/nozzle emissions and minimizes puff emissions from the removal of a 

vehicle’s gas cap. Two stakeholders and two equipment vendors support the use of balance 

Stage II VRS because these systems are proven to be compatible with ORVR. One equipment 

vendor said that they have data that demonstrates an increase in fugitive emissions as ORVR 

vehicle fleet penetration increases due to the incompatibility of vacuum assist Stage II VRS and 

ORVR. 

The Connecticut DEP and NESCAUM requested that EPA completely evaluate and 

quantify the incompatibility issues associated with Stage II VRS and ORVR so that States can 

make better informed decisions. Connecticut DEP also stated that EPA should consider 

implementing technology to reduce or eliminate excess emissions from incompatibility as the 

widespread use date approaches (i.e., UST add-on APCD, CARB’s EVR program, and P/V 

valves). ARID also requested that EPA conduct testing to accurately quantify IEE. 
DRAFT 2-07-06 

34

API and STI stated that the incompatibility issues associated with vacuum assist Stage II 

VRS and ORVR are not significant when taking into account that ORVR reduces vehicle 

fillpipe/nozzle emissions and minimizes puff emissions. STI noted that the magnitude of 

emissions decrease at the fillpipe (due to ORVR) is greater than the magnitude of the emissions 

increase due to pressurization of the UST (due to the incompatibility of vacuum assist Stage II 

VRS and ORVR). 

The Missouri DNR, RSA, Husky, and EMCO stated their support for balance Stage II 

VRS because these systems are proven to be compatible with ORVR. The Missouri DNR and 

Husky stated that the combination of balance Stage II VRS and ORVR enhances the overall 

control efficiency of the Stage II VRS. 

2. Discussion and Recommendation 

The incompatibility between the ORVR technology and the Stage II VRS (vacuum assist 

technology only) is a key issue for the Stage II VRS program. However, some of the 

stakeholders consider this issue moot because they believe Stage II VRS should be completely 

removed as it is a redundant control technology. These “redundant” VOC control devices 

(ORVR and some vacuum assist VRS) cause excess emissions when both are employed. 

However, when both balance VRS and ORVR are employed, the VOC emissions reductions 

approach 99 percent according to research by Missouri DNR; thus Missouri DNR plans to 

continue requiring balance Stage II VRS after any widespread use determination. In addition, 

CARB will probably be requiring Stage II VRS (both balance and vacuum assist) despite 

widespread deployment of ORVR and will require gasoline dispensing equipment to be certified 

through their testing program to ensure that excess emissions are not caused by the 

incompatibility of the ORVR and VRS technologies. Some emissions testing conducted by API 

indicates that the excess emissions from the incompatibility of ORVR and vacuum assist VRS 

are not significant, are dependent on which type of vacuum assist VRS is used (i.e., the V/L ratio 

is an important factor), and that the costs for implementing compatible ORVR and vacuum assist 

VRS are very expensive. 

Despite what some stakeholders believe about the need to eliminate Stage II VRS, we 

believe that there is merit to the idea to provide SIP credits for State and Local air pollution 

control agencies (APCA) that choose to retain Stage II VRS after the widespread use date; many 

APCAs were in favor of this idea. If so, then it would be desirable for EPA to collect additional 

data to further characterize the excess emissions from ORVR-Stage II vacuum assist 

incompatibility. 

There are some data from emissions testing by CARB and API showing there are excess 

emissions caused by the incompatibility of the vacuum assist VRS and ORVR (see section 

VI.A). However, their emissions testing results do not agree and, as a result, we believe it would 

be desirable to obtain additional emissions monitoring data to better understand this relationship. 

CARB and the Western States Petroleum Association (WSPA) plan to conduct some emissions 

testing to better define these emissions, however, when their testing will occur is unclear. Hertz 

is planning to conduct some emissions testing that will include vehicle refueling fillpipe interface 

and UST vent testing and tank pressure tracking. In addition, Hertz will be conducting testing to 

demonstrate that withdrawing vacuum assist Stage II VRS will not adversely impact VOC 

emissions from their GDFs. As part of this testing, they will be monitoring fillpipe emissions. 
DRAFT 2-07-06 

35

Because most of their vehicles are ORVR-equipped and the Stage II VRS are vacuum assist, 

there will likely be excess emissions data from incompatibility. NH DES, University of New 

Hampshire (UNH), Gilbarco/Veeder Root (GVR), and EFPAG are planning an emissions 

monitoring project that will provide more data on the excess emissions from incompatibility. 

We believe all of the aforementioned testing will enable EPA to better quantify the excess 

emissions from incompatibility and develop policy based on the “better” data. These tests are 

scheduled to be conducted in 2006. See section VI.D for more information. 

We recommend that the AQSSD’s Ozone Policy and Strategies Group (OPSG) wait until 

the results of these studies are finalized before coming to any conclusions about the excess 

emissions from the incompatibility of Stage II VRS (some vacuum assist) and ORVR. We are 

working closely with the participants in these studies to set up monitoring protocols that provide 

quality data. We have and will observe the testing to ensure that the data collected are quality 

data. 

Table 4. ORVR and Stage II VRS Compatibility Comment Summary 

Stakeholder Comment Summary Comment Details

Connecticut DEP Connecticut DEP asked EPA to 

evaluate and quantify the 

incompatibility issues related to 

Stage II VRS and ORVR. 

The Connecticut DEP stated that EPA should 

consider implementing technology to reduce or 

eliminate excess emissions from incompatibility as 

the widespread use date approaches. 

Costco Costco commented that prior to the 

installation of a membrane 

processor, vent episodes were 

measured, and these measurements 

showed that the UST vent was 

venting almost all day long due to 

the incompatibility of their vacuum 

assist VRS and ORVR. 

Costco commented that their policy was to install 

vacuum assist Stage II VRS at all their GDF, even in 

areas where it was not required. Their policy has 

changed due to the incompatibility of vacuum assist 

VRS and ORVR. Costco also stated, “Perversely 

and ironically, Stage II VRS increase emissions 

when used to fuel ORVR vehicles.” 

Ohio EPA Ohio EPA stated concern regarding 

the need for area-specific Stage II 

VRS data (i.e., whether vacuum 

assist or balance, and if vacuum 

assist, what brand or type of system) 

when addressing incompatibility. 

The Ohio EPA stated, “If a state chooses to address 

incompatibility in its SIP, or if USEPA requires 

SIPs to address incompatibility, shouldn’t there be 

data on the types and relative numbers of Stage II 

VRS control systems regarding incompatibility?” 

Ohio EPA suggested that the data could be areaspecific or use EPA default values. 

TCEQ The TCEQ stated that their Stage II 

VRS program is affected by the 

high percentage of vacuum assist 

VRS present in Texas. 

TCEQ commented that the Houston-Galveston 

nonattainment area has approximately 92 percent 

vacuum assist VRS compared to a national average 

of 47 percent. TCEQ also stated that, most current 

vacuum assist systems have varying degrees of 

incompatibility with ORVR systems, some of which 

result in excessive fugitive and vent emissions from 

GDFs. 
DRAFT 2-07-06 

36

Stakeholder Comment Summary Comment Details

NESCAUM NESCAUM indicated that they are 

concerned about the number of 

vacuum assist VRS that are located 

in their member states; the potential 

excess emissions that result from 

ORVR-equipped vehicles refueling 

at these stations may result in a 

significant source of new emissions. 

NESCAUM further stated, “Given 

the nonattainment status of some of 

these areas, allowing these 

emissions to remain unchecked 

could have significant air quality 

and public health ramifications.” 

NESCAUM stated “[s]tates are concerned with the 

potential public health threat that might result as a 

consequence of ORVR incompatibility with vacassist Stage II systems. States urge EPA to 

immediately undertake a detailed study to quantify 

and document the potential emissions attributable to 

ORVR incompatibility. If ORVR incompatibility is 

determined to be a significant source of emissions, 

NESCAUM recommends that the EPA develop 

strategies that will not result in a detriment to public 

health. Such a finding must also not result in any 

penalty to the program effectiveness of Stage II 

currently claimed in state ozone SIPs.” 

Missouri DNR Missouri DNR stated that they do 

not believe that there is a 

compatibility issue with the Stage II 

vapor recovery program for balance 

systems. Missouri DNR indicated 

those Stage II vacuum assist VRS in 

their present form are incompatible 

with ORVR. 

- Missouri DNR said that the balance system only 

enhances ORVR and that the two technologies 

together are capable of achieving over 98 percent 

efficiency. 

- Missouri DNR maintained that by eliminating 

vacuum assist VRS, incompatibility excess 

emissions are also eliminated. 

RSA RSA suggested that Stage II VRS 

requirements should be maintained 

and only the use of balance VRS 

should be allowed. 

RSA asked the question, “Does it make sense to 

allow the continued use of Assist VRS with their 

higher emissions than Balance VRS even without 

the ORVR incompatibility and increasingly higher 

emissions with the ORVR incompatibility?” 

CARB CARB stated that they disagree with the Stage II 

Issues Paper statement that “API data show the 

miniboot reduces excess emissions” because 

“CARB tests define excess emissions due to ORVR 

incompatibility as additional fugitive and vent 

emissions during fueling of ORVR vehicles.” 

API API stated that there are 

incompatibility issues with vacuum 

assist Stage II and ORVR. 

API further stated that these 

incompatibility issues become 

negligible when taking into account 

that ORVR reduces fill pipe 

emissions and minimizes puff 

emissions from the removal of a gas 

cap. 

API commented, “As described in the API ORVR 

compatibility study and the attached STI technical 

comments, some vacuum assist systems are less 

compatible with ORVR than others. Accounting for 

these different systems and their relative vaporemission control capabilities would be difficult at 

best.” 
DRAFT 2-07-06 

37

Stakeholder Comment Summary Comment Details

STI STI indicated concern with respect 

to issues of clearly defining the 

terms “ORVR compatibility” and 

“excess emissions,” and the 

quantification of emissions. STI 

suggested that the terms “excess 

emissions” and “incompatibility 

emissions” be defined so that the 

definitions incorporate the total 

emissions due to refueling. 

STI discussed testing conducted by 

CARB and API, specifically that 

CARB testing did not take into 

account the reduction of fillpipe 

emissions from ORVR, which was 

quantified in the API testing. 

STI also suggested that ORVR may 

reduce emissions from the initial 

puff that is emitted from the 

removal of a vehicle’s gas cap. 

STI stated, “If the magnitude of the emissions 

decrease at the fillpipe is greater than the magnitude 

of the increase in emissions due to pressurization, 

the net effect of ORVR systems is beneficial, i.e., 

they are reducing total refueling emissions. 

However, it appears that EPA’s issue paper (p. 10) 

defines the terms “excess emissions” and 

“incompatibility excess emissions” based solely on 

the change in pressurization-related emissions. This 

definition can easily be misconstrued, since the 

terms “excess emissions” and “incompatibility” 

often result in a perception that emissions from a 

VRS are increased by ORVR.” 

- STI commented that an API-sponsored study 

found that in seven out of eight tests, puff emissions 

were lower for ORVR-equipped vehicles than those 

from non-ORVR vehicles by 3-5 grams per 

refueling event. 

Hertz Hertz stated that there are 

incompatibility issues with current 

Stage II systems and ORVR, which 

results in IEE. 

Husky Husky stated that the Issues Paper 

does not take into account that 

required ORVR compatible Stage II 

systems are more efficient. 

Husky indicated that an ORVR-compatible Stage II 

VRS is at least 95 percent efficient verses 85 percent 

efficiency before ORVR. Husky further commented 

that ORVR compatible balance Stage II VRS 

achieves an efficiency of almost 99 percent because 

ORVR-equipped vehicles cause the VRS to operate 

at a negative pressure. Husky also stated that 

ORVR compatible vacuum assist Stage II VRS are 

also more efficient because the systems maintain a 

negative pressure. 

EMCO EMCO noted that balance systems 

have been proven to be compatible 

with ORVR by CARB and that 

converting a VRS to a balance is not 

expensive. 

VST VST stated that they have data that 

indicate that the increase of ORVR 

vehicle penetration is increasing 

fugitive emissions when used in 

conjunction with vacuum assist 

Stage II VRS. 

VST indicated that a growing trend of ORVRequipped vehicles in California is contributing to an 

increase in fugitive emissions. VST test data 

indicated the following increase in ORVR fleet 

penetration: 

Test Date 8/02 2/04 7/04 

ORVR Penetration 26% 38% 44% 

 
DRAFT 2-07-06 

38

Stakeholder Comment Summary Comment Details

ARID ARID suggested that EPA conduct 

testing to accurately quantify the 

incompatibility excess emissions 

(IEE). 

ARID stated that their measured and modeled data 

show a remarkable increase in the incompatibility 

excess emissions generated in the UST as a result of 

the fundamental incompatibility of Stage II vacuum 

assist and ORVR technologies. ARID provided IEE 

data from two test sites. 

E. Widespread Use Calculation and Date 

As discussed earlier in this paper, EPA has defined four possible ways to interpret 

widespread use. 

1. Comment Overview 

Five stakeholders commented that they support definition (c), or a similar definition, for 

widespread use (VOC emissions from ORVR controls equal VOC emissions from Stage II VRS 

only). Five stakeholders commented that they support definitions (a), (b), or (d) primarily due to 

the simplistic nature of these definitions. A couple of stakeholders stated that definition (c) is 

much too complex and not consistent with what Congress intended. One stakeholder indicated 

that the widespread use date may not affect them because they expect to maintain Stage II VRS 

after the widespread use date. A couple of stakeholders suggested alternative definitions for 

defining widespread use. One equipment vendor stated that they do not support the idea that 

Stage II VRS will become a redundant technology when ORVR becomes prevalent in the vehicle 

fleet, given that 20 percent of gasoline dispensed currently and in the foreseeable future will be 

to non-ORVR vehicles. 

NESCAUM urged EPA to adopt a policy that defines widespread use based on 

demonstrating that ORVR achieves emissions reductions equal to those reductions claimed by 

States in their SIPS; the widespread use definition should factor in the effect of vehicles in the 

fleet that will never have ORVR. The Connecticut DEP stated that they agree with 

NESCAUM’s suggestions for determining widespread use. 

Virginia stated that they prefer definition (c) because it is the most appropriate way to 

determine widespread use. Virginia suggested that EPA use locality-specific inputs in their 

algorithms to compute IEE and emptying and breathing losses of UST. NJDEP noted their 

preference for definition (c), but pointed out two concerns that they have with this definition. 

NJDEP stated that they do not believe that 100 percent rule effectiveness for ORVR is an 

accurate assumption and that the MOBILE6 model can not run all of the scenarios presented in 

the Issues paper. 

From a modeling standpoint, TCEQ preferred definition (b). Wisconsin DNR suggested 

using either definition (a) or (b), which are simple approaches. If definition (c) is chosen by 

EPA, both TCEQ and Wisconsin DNR requested that EPA provide guidelines on how States can 

use readily available data to determine in-use efficiency of their Stage II VRS. 
DRAFT 2-07-06 

39

CARB commented that widespread use may not apply to California because they expect 

to show an emissions benefit by continuing the use of Stage II VRS even after ORVR-equipped 

vehicles are in widespread use. 

The Ohio EPA suggested that EPA consider a simple and direct comparison for 

determining widespread use; the simplest comparison is determining when the amount of 

gasoline dispensed to ORVR-equipped vehicles is equal to the amount of gasoline dispensed by 

means of Stage II VRS. Missouri DNR stated that removing Stage II VRS would be premature 

because there will always be a significant number of vehicles in the fleet that will not be 

equipped with ORVR. Missouri DNR recommended that widespread use be defined at the point 

where emissions from ORVR crosses the emissions from balance Stage II VRS, which yields a 

widespread use date near 2030. 

API encouraged EPA to determine a widespread use definition that follows 

Congressional intent; API supported definitions (b) or (d) because these definitions reflect a 

common sense interpretation of the term widespread use. API suggested that under these 

definitions, EPA examine when the percentage of ORVR systems installed is equivalent to the 

Stage II VRS in-use efficiency that is in a given SIP. NACS and SIGMA also recommended that 

EPA use a common sense approach in determining widespread use; they stated that definitions 

(a), (b), or (d) reflect a reasonable interpretation and follow a common sense approach. NACS 

and SIGMA suggested that EPA consider using the median Stage II VRS in-use efficiency value 

from State SIPs. 

Hertz stated that the most conservative definition of widespread use should be when the 

vehicle fleet is comprised of 95 percent ORVR-equipped vehicles. 

2. Discussion and Recommendation 

As noted from the comments above, the stakeholders are very concerned about 

determining a widespread use date and the method used to determine the widespread use. The 

Clean Air Act Amendments of 1990 give little background to the intent of Congress for 

widespread use and the language in the Act give little guidance on how to determine widespread 

use. Mike Thrift of EPA’s Office of General Counsel, opined, “...statutory language gives us 

substantial discretion to define “widespread” and “throughout,” and even “the” with respect to 

“m.v. fleet.” Of course, the legislative history may shed some light on how Congress thought we 

ought to interpret the language, but under the Chevron doctrine, courts have not generally ruled 

that contrary legislative history, on its own, removes an agency’s discretion to interpret 

ambiguous statutory language. As long as we define these words and phrases reasonably 

through a notice and comment process (e.g., a rulemaking to waive Stage II VRS in serious, 

severe, and extreme areas), the courts will give us deference in interpreting the Act, even if they 

think that a different interpretation is better. Under Chevron, we only have to be reasonable, not 

“best” in the court’s view, unless the court rules that the language leaves us no discretion and 

that our interpretation is plainly contrary to its one clear meaning.”5042 We interpret his statement 

to mean that we can choose an approach (interpretation) for widespread use as long as we can 

defend it. 

 

50 Personal communication (email) from Mike Thrift to Tom Driscoll, February 22, 2005. 
DRAFT 2-07-06 

40

Generally, the comments are divided between those, industry and some states, wanting a 

simple and direct determination of widespread use [supported definitions (a), (b), or (d)] and 

those, most of the states, wanting the more complicated approach to determining widespread use 

[supported definition (c)]. Industry believes widespread use should be based on when most of 

the cars have ORVR canisters installed, when most of the gasoline pumped into ORVR-equipped 

vehicles, or when most of the VMT are miles traveled by ORVR-equipped vehicles. For a more 

thorough discussion of the definitions, see the Stage II VRS Issues Paper, pages 18-20. There 

are a couple of other issues associated with the widespread use date including: (1) if definitions 

(a), (b), or (d) are chosen, then what percentage of the vehicles, gas pumped, etc. makes sense to 

use as achieving widespread use; i.e., 85, 90, or 95 percent? and, (2) can the Ozone Transport 

Region (OTR) States determine a regional widespread use date? 

API stated in their comments that definitions (b) and (d) represent a common sense 

approach and the data to make the decision are easy to obtain. Some States noted that some of 

the data required for definition (c) may be difficult to obtain. Easy to obtain data is one of the 

primary benefits to choosing definitions (a), (b), or (d). However, determining a percentage, 

which is needed for definitions (a), (b), and (d), as having achieved widespread use would be 

somewhat arbitrary and difficult to defend. For example, is 50 percent ORVR-equipped vehicles 

considered widespread use, or is 95 percent gasoline pumped to ORVR-equipped vehicles 

considered widespread use? In their comments, API discussed the merits for using some 

percentages as opposed to others. 

In a follow-up letter from API, they suggested a new definition (c2) that is based on the 

date when emissions with ORVR-only controls are less than the emissions with combined Stage 

II VRS and ORVR controls, including incompatibility emissions.5143 This definition would 

clearly identify the date at which there would be no emissions increase as a result of removing 

Stage II VRS. We subsequently added a new definition (c2) to our list: 

Definition (c2) (VOC emissions with ORVR controls equal the VOC emissions with 

combined Stage II VRS and ORVR controls, with incompatibility excess emissions). Definition 

(c2) is similar in complexity to definition (c). One advantage with this approach is that there 

would be no possible increase in emissions from the decommissioning of Stage II VRS controls, 

as there might be with definition (c). One disadvantage with this approach, in addition to the inuse control efficiency for Stage II VRS mentioned for definition (c), is that the incompatibility 

excess emissions (IEE) factor must also be correctly determined. There is some disagreement 

over the quantity of these emissions. 

In comparison to definitions (a), (b), and (d), definitions (c) and (c2) are more tied to 

actual air quality impacts. These approaches make sense for what EPA is trying to achieve. In 

other words, we don’t want to remove Stage II VRS until we are sure that ORVR will achieve 

and continue to achieve the equivalent VOC emissions reductions. Using definition (c) makes 

more sense if EPA provides SIP credits. The negative side to selecting definitions (c) or (c2) is 

that it requires knowing the control efficiency for Stage II VRS programs in each State, the 

 

51 Memorandum from T. Tamura, STI, to P. Searles, API. Onboard Refueling Vapor Recovery (ORVR) Systems – 

Proposed Definitions of Widespread Use. March 3, 2005. 
DRAFT 2-07-06 

41

control efficiency for ORVR, and the quantity of IEE. States will be looking to EPA to answer 

these issues. 

There are some other elements that need to be factored into this discussion. Some 

vehicles (such as motorcycles, lawn mowers, and some large vehicles) will never have ORVR. It 

will be difficult to quantify the VOC emissions from refueling these types of vehicles. Missouri 

DNR suggested that up to 20 percent of vehicles will never have ORVR. We are not sure that 20 

percent is correct, but we know only definitions (c) and (c2) account for this factor. In a 

streamlined estimate of the percentage of gasoline vehicles never to have ORVR (based on all 

gasoline vehicles), based on 1996 national fleet data, 94 percent of all gasoline vehicles will 

eventually have ORVR controls.5244 The 1996 national fleet data were used as the basis to 

develop the MOBILE6 defaults. This analysis used conservative assumptions, namely an 

assumption that no HDGV class 2B vehicles will ever be ORVR, even though some vehicles in 

this class will be covered (complete vehicles). 

An analysis of the gasoline dispensed to ORVR-equipped vehicles has not been 

conducted. It is true that larger, never-to-be-covered non-ORVR vehicles would likely fuel large 

amounts of gasoline per vehicle, but they represent a small portion of the fleet (approximately 

3.6 percent of the gasoline fleet). While fueling of motorcycles (approximately 2.3 percent of 

the gasoline fleet) and other motor-driven equipment may represent a large number of fuelings, 

the individual gasoline volume dispensed for each event is small and may not represent a large 

portion, either. Vacuum assist Stage II VRS do recover the refueling emissions from motorcycle 

refueling and filling of other motor-driven equipment, however, balance VRS do not control 

these refueling emissions. Some states (California and Missouri, for example) may choose to 

continue Stage II VRS, despite any widespread use determination. We need to ensure any policy 

or regulation we develop will not undermine their decisions/efforts. 

The algorithm needed to determine widespread use depends on the definition chosen. For 

definitions (a), (b), and (d), relatively straightforward calculations requiring specific information 

such as the gallons of gasoline pumped and the vehicle registration and age distribution will be 

needed. We have thought in the past that the more simple definitions, for example definition (a), 

may be easier for States to use, however, some States have had difficulties in assembling vehicle 

registration data. The definitions we have termed as “easier-to-use” or “State-friendly” may be 

just as problematic for some States as the more complicated definitions are for other States. 

Definitions (c) and (c2) require more information and many specific pieces of information. 

Algorithms from the MOBILE6 model (with some minor modifications), which most every State 

uses, can be used to compute widespread use for definitions (c) and (c2). With definition (c2), it 

will be desirable for EPA to better characterize the IEE. EPA likely will have to determine the 

IEE for multiple types of vacuum assist systems (GVR, WayneVac, etc.) as the IEE depends on 

the V/L ratio. In addition, States, if they have not already done so, will have to determine what 

the Stage II VRS in-use control efficiency is in their State based on I/M programs conducted and 

any throughput cutoffs for applicability, and EPA will need to make a determination on the longterm in-use control efficiency for ORVR controls. As mentioned previously, the initial data on 

 

52 Memorandum from K. Schaffner, RTI, to T. Driscoll, EPA/OAQPS/EMAD. Streamlined Estimate of Gasoline 

Vehicles Never to Have ORVR. September 30, 2005. 
DRAFT 2-07-06 

42

ORVR seems to confirm that ORVR continues to work long-term, and EPA is tracking this issue 

with continued testing programs. 

Because the OTR States have separate requirements for ozone than other States, they 

have asked for the ability to make a widespread use determination for the entire region. Section 

184(b)(2) requires: (1) EPA to conduct a study to identify emissions reductions control measures 

comparable to Stage II controls (called comparable measures), and (2) OTR States to revise their 

SIPs to require Stage II or comparable measures. For more specific information regarding OTR 

requirements, see the EPA Stage II Issues Paper on pages 3 and 4. There were no stakeholders 

that opposed the proposal to allow separate considerations for the OTR States, and we 

recommend that the OTR be allowed to proceed in their determination on a regional basis, if that 

is their preference. 

Again, we believe that the planned emissions monitoring described in section VI.D will 

give us more qualitative information on the IEE to make a better decision regarding widespread 

use. Nevertheless, based on the information and comment responses we have, we believe 

definitions (c) and (c2) as the best option for determining widespread use. We believe either of 

these definitions is defendable. Definition (c2) would not allow increases in VOC emissions 

when transitioning from the combined ORVR/Stage II VRS to ORVR systems only. Definition 

(c) would also allow the widespread use date to be determined based on emissions, and SIP 

credits could be offered for those States who continue requiring Stage II VRS beyond the 

widespread use date. 

As mentioned previously in the Issues Paper, the definitions may be inter-related and may 

provide similar results, so we have conducted an analysis of the definitions for 3 States to test 

this hypothesis. We collected data from 3 States and estimated the widespread use date for all 

five definitions for each State. A preliminary summary is provided in section VII. This analysis 

allowed us to see the range of values and determine if the definitions are the same or if one is 

truly different. The results for these States show that definitions (b), (c2), and (d) are fairly 

similar. For these States, definition (c) would result in the earliest widespread use date; both 

definitions (c) and (c2) are affected by the in-use control efficiency for Stage II VRS and 

definition (c2) is affected by the magnitude of the IEE. Initial data from Vermont indicate that 

definition (a) would provide the latest widespread use date. For these States, a percentage of 

approximately 85 percent for VMT for ORVR vehicles (b) and for gasoline throughput for 

ORVR vehicles (d) falls somewhere between the (c) and (c2) definitions. 

In conjunction with recommending definitions (c) or (c2), we also recommend that 

algorithms to determine widespread use be based on the MOBILE6 model. EPA is addressing 

the issues with respect to these definition choices, namely we have emissions testing planned to 

quantify the IEE and the EPA Office of Mobile Sources (OMS) is investigating control 

efficiency for ORVR. Some additional work may have to be done to help States with in-use 

control efficiencies for Stage II VRS. Finally, we recommend that the OTR States be allowed to 

have a region-wide determination and we should start the process to allow region-wide 

determination (by amending the comparability study or other acceptable method). 
DRAFT 2-07-06 

43

Table 5. Widespread Use Calculation and Date Comment Summary 

Stakeholder Comment Summary Comment Details

NESCAUM NESCAUM preferred a 

widespread use definition 

similar to definition (c). 

NESCAUM urged EPA to 

adopt a policy that defines 

widespread use based on 

demonstrating that ORVR 

systems achieve VOC 

emissions reductions equal to 

those reductions claimed by 

States in their SIPs. 

- NESCAUM asked EPA to issue guidance for States to make a 

determination. NESCAUM stated, “[i]f EPA decides to use to 

choose an alternative method (e.g., defining widespread use to 

the percentage of ORVR vehicles in the fleet or gasoline 

dispensed to ORVR vehicles) the Agency should still tie these 

numbers to a technical basis, including air quality modeling, in 

order to assure that removal of the Stage II program does not 

degrade air quality.” 

- NESCUAM further suggested that EPA perform a modeling 

exercise on several “pilot” states to determine if a correlation 

exists between the one-for-one equivalency and percent of 

ORVR vehicles in the fleet; if the exercise indicated a 

statistically significant correlation, NESCAUM would then 

support that method for determining widespread use. 

- NESCAUM suggested that EPA factor in the effect of vehicles 

in the fleet that will never have ORVR when determining 

widespread use. 

- NESCAUM also made suggestions for those areas where the 

Stage II program is not implemented statewide; EPA should 

calculate emissions in these areas based on gasoline dispensed to 

ORVR vehicles in those counties where Stage II controls exist. 

Connecticut 

DEP 

Connecticut DEP suggested 

that EPA adopt a definition 

that preserves the effectiveness 

of existing Stage II programs. 

Connecticut DEP stated that 

they agree with NESCAUM’s 

procedure for determining the 

definition of widespread use. 

Connecticut DEP stated that: 

(1) Before States are allowed to drop Stage II VRS programs 

after the applicable widespread use date occurs, EPA needs to 

complete a study to confirm that ORVR systems will properly 

operate over the useful life of a vehicle; and 

(2) EPA should consider implementing technology to reduce or 

eliminate excess emissions from incompatibility as the 

widespread use date is reached. 

Virginia Virginia preferred definition 

(c). 

– Virginia stated that definition (c) is the most appropriate way 

to determine “widespread use.” Virginia also supports an 

uniform nationwide widespread use definition. 

– Virginia stated that in the development of a widespread use 

algorithm, EPA should develop an algorithm to compute the 

magnitude of “incompatibility excess emissions,” using localityspecific inputs. 

- Virginia also stated that an algorithm should be developed for 

determining emptying and breathing emissions; algorithm 

should incorporate locality-specific data. 

CARB CARB maintained that 

widespread use may not apply 

to California since CARB 

expects to show an emissions 

benefit by continuing the use 

of Stage II VRS even after 

ORVR-equipped vehicles are 

in widespread use. 

CARB also commented that the Stage II Issues Paper should 

probably be revised to say that CARB will retain Stage II VRS 

after the widespread use date, “if there is an emissions benefit.” 
DRAFT 2-07-06 

44

Stakeholder Comment Summary Comment Details

NJDEP NJDEP preferred definition 

(c). 

The NJDEP had the following two issues with definition (c): 

(1) does not believe that 100 percent rule effectiveness for 

ORVR is accurate, and 

(2) NJDEP cannot run the MOBILE6 model using all the 

scenarios presented in the Issues Paper. 

NJDEP added that if the MOBILE6 model is not revised to 

allow state-specific emissions calculations, then definition (b) 

may be more appropriate. 

TCEQ TCEQ stated that definition (b) 

from a modeling standpoint 

would be the easiest and most 

realistic way to determine 

widespread use. 

- TCEQ stated that the method of determining widespread use 

would have a significant impact on their program since 

promulgating ORVR compatible requirements. “It is possible 

that widespread use, depending on the definition chosen by the 

EPA, could occur relatively soon after the TCEQ’s ORVR 

compatibility deadline for existing Stage II systems which is 

April 1, 2007.” 

– TCEQ requested that if definition (c) is used, then EPA should 

provide guidelines on how States can use readily available data 

to determine in-use efficiency for existing Stage II VRS. 

– TCEQ stated that any widespread use definition requiring data 

on the percentage of gasoline dispensed would require additional 

reporting because Texas GDFs are not currently required to 

report gasoline throughput information. 

Wisconsin 

DNR 

Wisconsin DNR suggested 

using either definition (a) or 

(b). 

– Wisconsin DNR commented, “[i]ncorporating either of the 

simple approaches with the development of an algorithm may be 

sufficiently accurate for projecting the approximate time when 

widespread use occurs.” 

– Wisconsin DNR said that they agree with EPA’s suggested 

approach to use one widespread use definition for all States and 

having state-specific inputs to make the widespread use date 

applicable to that state. 

– Wisconsin DNR also stated that they agree that when Stage II 

VRS are removed that the continued use of Pressure/Vacuum 

(P/V) valves should be required. 

– Wisconsin DNR stated that if EPA chooses option (c), EPA 

needs to provide states with information on how states can use 

readily available data to determine in-use control efficiency of 

Stage II VRS. 

Ohio EPA Ohio EPA suggested that EPA 

consider a simple and direct 

comparison for determining 

widespread use. Ohio EPA 

stated that the simplest 

comparison for widespread use 

is determining when the 

amount of gasoline dispensed 

to ORVR-equipped vehicles is 

equal to the amount of 

gasoline dispensed by means 

of Stage II VRS. 

Ohio EPA commented, “The issues of incompatibility, ruleeffectiveness for Stage II, and spillage for ORVR vs. Stage II 

would not be considered due to the complexities and relative 

inaccuracies associated with evaluating such issues. Also, the 

nominal control efficiencies for Stage II and ORVR would not 

be considered significantly different. In the event USEPA 

considers the nominal control efficiencies to be significantly 

different (e.g., 95 percent for pre-EVR Stage II and 98 percent 

for ORVR), the comparison of gasoline dispensed to ORVRequipped vehicles and dispensed by means of Stage II could 

include an adjustment factor for nominal control efficiencies.” 
DRAFT 2-07-06 

45

Stakeholder Comment Summary Comment Details

Missouri 

DNR 

Missouri DNR stated that they 

believe that ending Stage II 

VRS would be premature; 

balance systems complement 

ORVR, yielding a control 

efficiency greater than 98 

percent. 

- Missouri DNR provided data that indicates there will always 

be a significant number of vehicles that will never have ORVR; 

they strongly suggest that Stage II balance VRS not be 

discontinued. 

- Missouri DNR suggested another possible definition for 

widespread use that is derived from Figure 6 from the Issues 

Paper; widespread use could be defined as the point where 

ORVR only crosses or joins balance Stage II VRS only, which 

yields a date sometime near 2030. 

API API stated that they support 

definitions (d) or (b) because 

they reflect a common sense 

interpretation of the term 

“widespread use.” 

Conversely, the API 

maintained that definition (c) 

is too complex and not 

consistent with what Congress 

intended. 

For definition (d), API 

suggested that quantities of 

gasoline dispensed on a 

countywide basis could be 

calculated from countyspecific VMT data by using 

fuel economy data 

incorporated into the 

MOBILE6 model. 

API indicated that they support 

a widespread use definition 

that is applied on an area-byarea and/or regional basis. 

API also offered to work with 

EPA on how to determine an 

alternative baseline for the 

OTR so that OTR States can 

take credit for ORVR. 

– API stated that “[t]he consumer is already paying for ORVR 

systems on their vehicles and should not have to pay again for 

the maintenance of redundant vapor controls at the gasoline 

dispensing facility. State environmental agencies should not be 

asked to implement Stage II VRS programs after widespread use 

is determined since ORVR and Stage II are duplicative 

technologies.” API also commented that it is expensive for 

states to administer an effective Stage II VRS program and that 

states should be allowed to focus their air quality improvement 

efforts on programs other than Stage II VRS. 

– API added that “[u]nder Definitions (b) and (d), to identify the 

appropriate percentage that equates to ORVR widespread use, 

EPA should examine when the percentage of ORVR systems 

installed is equivalent to the Stage II in-use efficiency that is in a 

given SIP.” API provided the following example: If a state has 

an 85 percent efficiency for the Stage II VRS, then once 87 

percent of vehicles have ORVR, the state would have achieved 

widespread use. To calculate 87 percent, use the MOBILE6 

value of 98 percent efficiency for ORVR technology and then 

divide the in-use efficiency (in this example, 85 percent) by 98 

percent. 

– API also mentioned the spreadsheet they developed to 

calculate the percent of gasoline dispensed to ORVR-equipped 

vehicles based on VMT data and other MOBILE6 input data. 

API suggested that their spreadsheet could be updated with 

information with automobile manufacturers regarding when 

ORVR was actually implemented on the vehicles. 

– API stated that definition (c) would require data that is 

extremely difficult to ascertain. 

- API encouraged EPA to determine a definition of widespread 

use that follows Congressional intent. 

FPMA FPMA noted that definitions 

(a) and (b) meet the intent of 

Section 182(b)(3), and option 

(d) may meet the intent, while 

definition (c) goes far beyond 

whether ORVR is in 

widespread use and would be 

the most difficult calculation 

to make. 
DRAFT 2-07-06 

46

Stakeholder Comment Summary Comment Details

Healy Healy indicated that they do 

not agree with the Issues Paper 

assumption that the ORVR 

fleet penetration will at some 

point make Stage II VRS 

redundant. 

- Healy commented that a review conducted by CARB 

concluded that 20 percent of gasoline dispensed currently and in 

the foreseeable future will be non-ORVR vehicles; if Stage II 

VRS is removed, then 100 percent of non-ORVR refueling 

emissions will be emitted to the atmosphere. Healy used an 

equation to conclude that the vapor recovery efficiency after the 

widespread use date and dismantle of Stage II VRS would be 76 

percent. 

- Healy suggested that the widespread use calculation take into 

account the actual in-use control efficiency of ORVR. 

EMCO EMCO suggested setting the 

widespread use definition at a 

vehicle population percentage 

of 98 percent ORVR. 

EMCO commented, “Ostensibly both Stage II systems and 

ORVR vehicles run at 95 percent efficiency. Consequently if 

Stage II controls were removed from dispensing facilities when 

the vehicle population is 95 percent ORVR, the net effect on 

emissions would be zero. The 95 percent ORVR vehicle trigger 

would then be a logical starting point. However, allowing the 5 

percent non ORVR vehicles to begin refueling with no vapor 

recovery increases their emission rate by a factor of 20. This 

flies in the face of common sense. Surely any environmental 

protection advocate worth his weight in VOC’s would cringe at 

the prospect of abandoning the use of effective, proven methods 

of reducing refueling emissions.” 

RSA RSA indicated that definition 

(c) appears to be the most 

reasonable since it deals with 

real emissions and reduction of 

emissions. 

RSA stated that definition (c) requires an accurate determination 

of annual emissions for VRS and for ORVR under the following 

scenarios: 

1) For VRS emissions with no ORVR. Under this scenario RSA 

pointed out the following issues/questions: 

a. Will average annual emissions factors for VRS be used with 

average annual gasoline sales? 

b. Will the emissions factors be determined for the VRS in place 

or as an assumed efficiency multiplied by an uncontrolled 

emissions factor? 

c. Will the emissions factors include things such as the 

nozzle/fillport, spillage/pseudospillage, breathing, and vent 

emptying? 

2) For ORVR emissions. Under this scenario RSA pointed out 

the following issues/questions? 

a. Will hybrid vehicles be included along with the percentage of 

fuel used? 

b. How will data be broken down for a vehicle type (i.e., model 

year, make, or combination) 

c. Will SHED test data be used? 

3) For VRS and ORVR. Under this scenario RSA made the 

following comments: 

a. For a balance VRS, the nozzle/fillport efficiency increases to 

greater than 99 percent. 

b. A vacuum assist VRS may reduce the effectiveness of ORVR. 
DRAFT 2-07-06 

47

Stakeholder Comment Summary Comment Details

NACS, 

SIGMA 

NACS and SIGMA indicated 

that they are “particularly 

concerned” about EPA’s 

preference for definition (c); 

they stated that definition (c) 

would contradict the “clear 

policy choice of Congress in 

identifying ORVR as a 

superior technology.” NACS 

and SIGMA stated that 

definitions (a), (b), and (d) 

reflect a reasonable 

interpretation of what 

widespread use means and 

these choices reflect a more 

common sense approach. 

NACS and SIGMA stated that 

they would like EPA to give 

more consideration to 

definitions (b) and (d). 

- These groups stated, “NACS and SIGMA members have spent 

hundreds of thousands of dollars installing and maintaining 

Stage II systems over the last decade. These burdens were 

assumed as part of the compromise reflected in section 202(a)(6) 

of the Clean Air Act and subsequent promulgation of ORVR 

requirements: service station owners would install Stage II 

systems in certain nonattainment areas over the interim period 

until ORVR was in place in a majority of the vehicle fleet to 

control these same refueling emissions. The timeframe for 

achieving widespread use was envisioned as approximately 10- 

15 years after promulgation of ORVR requirements. We are now 

approaching, or possibly in some areas at, the point of 

widespread use of ORVR. NACS and SIGMA members have 

done their part in controlling refueling emissions. Consistent 

with what Congress intended, it is now time to phase out Stage 

II requirements and recognize and promote ORVR as the more 

equitable and effective approach to controlling refueling 

emissions.” 

- NACS and SIGMA commented that definition (c) misses the 

mark in defining widespread use and is an exercise in futility; 

definition (c) identifies “widespread effect” and not widespread 

use of ORVR. 

- NACS and SIGMA suggested that EPA consider using the 

median Stage II in-use efficiency value from State SIPs, given 

the difficulty in pinpointing a precise estimate of Stage II in-use 

efficiency, to identify the percentage that would define ORVR 

widespread use under Options (a), (b), or (d). 

Hertz Hertz stated that the most 

conservative definition of 

widespread use is 95 percent 

of the vehicle fleet being 

comprised of ORVR-equipped 

vehicles. 

ARID ARID noted that the extreme 

magnitude of incompatibility 

excess emissions should 

strongly influence the thought 

processes for the definition 

and supporting algorithms 

related to widespread use. 

 

F. Phase Out of Stage II Vapor Recovery Systems 

After the widespread use date is determined, EPA may decide to allow Stats or areas to 

repeal requirements for Stage II VRS 

1. Comment Summary 

Five stakeholders and one equipment vendor expressed concern regarding the phase out 

of Stage II VRS. One stakeholder stated that they would like to see the continued use of Stage II 

VRS because it would remain a critical element of an ozone attainment strategy. Two 
DRAFT 2-07-06 

48

stakeholders stated that Stage II VRS should not be adopted by new areas because there would 

only be marginal benefit at significant costs. One stakeholder commented that they would like to 

see the requirement for Stage II VRS at new GDF revoked in Southeast Florida. Lastly, one 

stakeholder suggested that Stage II VRS nozzles are costly, complex and difficult to use and 

believes that sooner rather than later replacement of Stage II VRS with ORVR will allow for 

nozzles to be built for durability, reliability, and safety instead of specifically for Stage II VRS. 

The Ohio EPA requested that an impact study be conducted before discontinuing Stage II 

VRS in nonattainment areas to determine the impacts of dismantlement. The Wisconsin DNR 

also indicated that they would like assurances that the disconnection of Stage II VRS would be 

monitored. TCEQ stated that faulty vacuum assist systems have the capacity to cause more 

fugitive and vent emissions than a GDF without Stage II VRS, and simply ceasing to investigate 

GDFs with Stage II VRS would harm air quality as numerous vacuum assist VRS would remain 

in service without maintenance or oversight. 

NESCAUM suggested that EPA take measures to ensure that States do not remove Stage 

II VRS if the removal would result in an increase in VOC emissions. NESCAUM also stated 

that new stations should not be required to install Stage II VRS if the widespread use date is near 

(i.e., within a year or two years) but instead use alternative measures. The CT DEP stated that 

Stage II VRS is an effective and efficient means of reducing ozone precursor emissions and as 

such, Stage II should not be phased out. CT DEP believes that continued use of Stage II VRS is 

necessary because only light-duty vehicles are required to have ORVR. The CT DEP also stated 

that the phase out of Stage II should not occur until ORVR effectiveness has been determined 

over the lifespan of the ORVR canister. 

The FPMA commented that there are two dates to consider related to the phase out of 

Stage II VRS: (1) the date after which Stage II VRS will no longer be required for new 

construction; and (2) the date after which Stage II VRS will not be required to be maintained at 

existing facilities. FPMA further stated that their primary concern is to obtain an immediate end 

to requiring Stage II VRS at new GDFs in Southeast Florida. 

Both API, NACS, and SIGMA stressed that Stage II VRS should not be adopted by new 

areas; the costs associated with this adoption would be excessive and are not justified by the 

diminishing marginal benefit of emissions reductions. 

2. Discussion and Recommendations 

There are two issues associated with these comments: (1) after the widespread use date is 

achieved, ensuring existing Stage II VRS are removed in a manner that does not increase VOC 

emissions from the GDF, and (2) should we allow GDFs built near, but before, the widespread 

use date to be granted an exemption from installing Stage II VRS? If so, then how long before 

the widespread use date can a station be built without Stage II VRS and what in-kind measures 

can we require to compensate for the subsequent VOC emissions from these GDFs? This is an 

equity issue; some believe it is not fair to existing GDFs with Stage II VRS requirements to 

allow an exemption to installing Stage II VRS for new GDFs. We agree. NESCAUM suggested 

that a cost-benefit analysis be conducted by EPA to determine what is the period of time, prior to 

the widespread use date, that newly built GDFs would not have to install Stage II VRS. 
DRAFT 2-07-06 

49

There is a concern that if Stage II VRS are not properly removed from GDF, then there 

will be resultant leaks as the system deteriorates or as replacement non-VRS equipment are 

installed. There is potential for fugitive VOC leaks if Stage II VRS remain in place and are not 

maintained and not sufficiently capped. There is also a potential for leaks if new equipment, 

such as nozzles, that are not Stage II VRS compliant, replace worn out Stage II VRS compliant 

equipment. Given the track record for GDF maintenance, we believe this issue is important to 

address. EPA should strongly consider providing guidance on minimal standards for removal of 

Stage II VRS equipment. OAQPS should work closely with the Office of Underground Storage 

Tanks (OUST) on removal requirements. 

All the stakeholders that responded were generally in agreement with allowing a waiver 

or exemption to new GDF built near the widespread use date. There were few comments on 

what control measures to implement in place of Stage II VRS. NESCAUM mentioned stricter 

Stage I requirements. Other measures that could be adopted would be more frequent inspections, 

monitoring of the system pressure, in-station diagnostics, requiring an add-on control device to 

the UST, etc. 

We recommend that EPA develop a policy, guidance, or rule requiring GDF to remove or 

decommission Stage II VRS equipment in a way that will minimize leaks. Another 

recommendation is that EPA allow States to grant waivers to GDF that are being built near the 

widespread use date. We recommend that EPA conduct a cost analysis to determine when new 

GDF would no longer be required to install Stage II VRS. In addition to waivers granted to these 

newly built GDF, we recommend that they be required to implement other VOC emissions 

reductions measures, such as dripless nozzles, UST add-on APCD, in-station diagnostics, or have 

the State increase inspections of the GDFs. We believe the State should have the latitude to 

choose the alternative emissions reductions measures, increase inspections, or some other 

equivalent measures as long as the State can show that the alternative VOC emissions reductions 

measure (in combination with ORVR emissions reductions) is equivalent to the VOC emissions 

reductions achieved by Stage II VRS. We recommend that EPA develop additional guidance on 

control measure options and the control efficiencies that can be achieved. Finally, we 

recommend that EPA develop guidance for allowing SIP credits for source owners or operators 

who retain Stage II VRS. 

Table 6. Phase Out of Stage II Vapor Recovery Systems Comment Summary 

Stakeholder Comment Summary Comment Detail

NESCAUM NESCAUM stated that EPA 

should take measures to 

ensure that a State can not 

eliminate Stage II VRS if 

removal of these systems 

would result in an actual 

emissions increase in VOC. 

NESCAUM proposed that new GDF not be required to install 

Stage II VRS and, instead, implement alternative measures 

(such as improvements to the control efficiency of the GDF 

Stage I system) so as not to gain an economic advantage over 

GDFs that previously had to install Stage II VRS. 

NESCAUM recommended that EPA conduct a cost-benefit 

analysis to determine when this “interim” period should start. 

TCEQ TCEQ has concerns that VOC 

emissions will increase if 

oversight of VRS ceases/stops 

once widespread use is 

achieved. 

TCEQ stated, “Because faulty vacuum assist systems have 

the capacity to cause more fugitive and vent emissions than a 

GDF without a Stage II VRS, simply ceasing to investigate 

GDFs with Stage II VRS would harm air quality as numerous 

vacuum assist VRS would remain in service without 

maintenance or oversight.” 
DRAFT 2-07-06 

50

Stakeholder Comment Summary Comment Detail

Connecticut 

DEP 

Connecticut DEP commented 

that they want to see 

continued use of Stage II VRS 

and requested that EPA 

require implementation of 

Stage II in ozone 

nonattainment areas as 

required by the CAA. 

Connecticut DEP stated, “Continued use of Stage II systems 

is necessary because only light duty vehicles are required to 

have ORVR canisters available. Connecticut DEP believes 

that Stage II systems will remain a critical element of an 

attainment strategy into the foreseeable future.” 

Ohio EPA Ohio EPA noted that an 

impact study should be 

conducted before 

discontinuing Stage II VRS in 

nonattainment areas to 

determine the impact of the 

discontinuance, while taking 

into account SIP projections. 

Ohio EPA stated, “The US EPA should identify all areas 

outside of the OTR that implemented Stage II, identify the 

basis for the implementation (e.g., to meet the 15 percent 

reduction requirement for 1996, to meet other reasonable 

further progress requirements, etc.), and identify the years for 

any emissions projections. This may uncover issues not 

considered by USEPA or may help resolve issues already 

considered by USEPA. Those non-OTR areas should be 

allowed to use either the above-suggested comparison for 

discontinuance of Stage II or a more complicated comparison 

of emissions that may include incompatibility, ruleeffectiveness, etc. pursuant to USEPA policy that results from 

this issues paper.” 

Wisconsin 

DNR 

Wisconsin DNR stated that 

they have concerns about 

disconnecting Stage II VRS. 

Wisconsin DNR indicated that 

they want assurances that the 

disconnection of Stage II VRS 

be properly monitored. 

Wisconsin DNR requested that EPA address this issue in the 

case that Stage II systems are no longer needed. 

FPMA FPMA stated that Stage II is a 

redundant technology and the 

VRS equipment has a limited 

useful life. 

FPMA noted that their 

primary concern is to obtain 

an immediate end to requiring 

Stage II VRS at new GDFs in 

Southeast Florida. 

- FPMA commented that there are two regulatory 

considerations to consider for phasing out Stage II VRS: (1) 

the date after which Stage II VRS will no longer be required 

for new construction; and (2) the date after which Stage II 

will not be required to be maintained at existing facilities. 

- FPMA stated “Our concern is that if EPA does not 

distinguish between areas formerly designated as “moderate” 

nonattainment and areas that are “serious” nonattainment or 

worse, regulators responsible for the previously “moderate” 

areas will apply the same “widespread use” criteria as EPA 

will apply to the “serious” or worse areas. It is our position 

that Stage II regulations in areas where Stage II was not 

required under the Clean Air Act ought to be repealed before 

Stage II is revised or waived in “serious” or worse 

nonattainment areas.” 

Healy Healy stated that additional 

steps, such as quantifying the 

gasoline dispensed to nonORVR vehicles, need to be 

taken before dismantling 

Stage II systems. 

Healy recommended that current data from the US 

Department of Transportation and other sources be used to 

determine the actual distribution of gasoline to ORVRequipped vehicles and to non-ORVR equipped vehicles in 

order to better calculate the impact of dismantling Stage II 

VRS. 
DRAFT 2-07-06 

51

Stakeholder Comment Summary Comment Detail

Costco Costco stated that they would 

like to see Stage II replaced 

with ORVR; replacement of 

Stage II VRS would allow 

manufacturers to build nozzles 

that are built for durability and 

reliability instead of 

specifically designed for VRS, 

which are costly, complex, 

and difficult to use. 

API API stated that they do not 

support the adoption of Stage 

II VRS in new areas. 

API commented, “The cost per ton VOC reduced by Stage II 

is rapidly growing as the ORVR is implemented in the 

vehicle fleet.” 

NACS, SIGMA NACS, SIGMA stated that 

EPA should not permit the 

expansion of Stage II VRS in 

new areas. 

These groups maintained that the costs associated with 

installing new or enhanced Stage II VRS are not justified by 

the diminishing marginal benefits that may be achieved 

before the widespread use date arrives. 

G. Phase Out of Stage II Vapor Recovery Systems in the OTR 

1. Comment Summary 

Two stakeholders indicated that they would like to see a mechanism developed that 

would allow OTR states the ability to phase out their Stage II VRS. 

NESCAUM recommended that EPA determine a regional phase-out date that is 

consistent with the latest date that an OTR state would achieve widespread use. NESCAUM also 

requested that EPA provide an early opt-out method for those OTR States that demonstrate that 

removal of Stage II VRS would not degrade air quality. Virginia also agreed that EPA should 

provide an additional mechanism for OTR States to phase out of the Section 184(b)(2) Stage II 

VRS, or comparable measure, requirement; requirement would be similar to the mechanism for 

moderate or worse nonattainment areas under Section 184(b)(3) to allow the removal of Stage II 

VRS once ORVR controls are determined to be in widespread use. Both NESCAUM and 

Virginia recommended updating the “Stage II Comparability Study.” 

2. Discussion and Recommendations 

The discussion and recommendations for this section are similar to those in Section V.F. 

Again, the recommendation is for EPA to allow OTR States to grant waivers to GDFs that are 

being built prior to the widespread use date, and we recommend that the GDFs that are granted 

waivers be required to implement other VOC emissions reductions measures, such as in-station 

diagnostics, or have the State increase inspections of the GDFs. We believe each OTR State 

should have the latitude to choose the alternative emissions reductions measures, increase 

inspections, or some other equivalent measures as long as the State can demonstrate that the 

alternative VOC emissions reductions measure (in conjunction with ORVR controls) is 

equivalent to the VOC emissions reductions achieved by Stage II VRS. As with the phase out 

for the rest of the country, the same guidance document on the decommissioning of Stage II VRS 

may be necessary. Because the “Stage II Comparability Study” must be updated or otherwise 
DRAFT 2-07-06 

52

amended to allow removal of Stage II VRS, we recommend that this process begin soon, with 

input from OTR States. 

Table 7. Phase Out of Stage II Vapor Recovery Systems in the OTR Comment Summary 

Stakeholder Comment Summary Comment Detail

NESCAUM NESCAUM indicated that they 

would like to see a pathway 

developed that would allow OTR 

states to phase-out their Stage II 

VRS programs. NESCAUM 

suggested that EPA determine a 

regional phase-out date that is 

consistent with the latest date that 

an OTR state reaches widespread 

use. 

- NESCAUM stated, “Under current EPA policy, the 

only pathway for phasing out Stage II in OTR states is 

the implementation of comparable measures equivalent 

to Stage II reductions achieved in 1999. Given this 

scenario, redundant vapor recovery programs (ORVR 

and Stage II) will run side-by-side in perpetuity unless a 

policy change is made at EPA. Therefore, the 

NESCAUM states support a revision of the 

Comparability Study to develop a pathway that would 

allow OTR states to phase-out their Stage II programs at 

the point where this does not result in increased 

emissions.” 

- NESCAUM would also like to see EPA provide an 

early opt-out method for those OTR states that are able 

to demonstrate that the removal of Stage II VRS would 

not increase VOC emissions nor degrade air quality. 

Virginia VA stated that EPA should 

provide an additional mechanism 

for OTR states to be able to phase 

out of the section 184 (b)(2) Stage 

II VRS or comparable measure 

requirement. 

VA suggested updating the “Stage II Comparability 

Study” with a baseline that coincides with the year that 

ORVR is determined to be in widespread use. 

H. Stage II State Implementation Plan (SIP) Credits 

As previously discussed in this paper, SIP credits could possibly be granted to States for 

maintaining Stage II VRS after the widespread use date, implementing Stage II VRS in 

additional areas, and implementing improved monitoring and/or control measures. 

1. Comment Summary 

Five stakeholders stated that they support granting SIP credits for maintaining Stage II 

VRS after the widespread use date. One stakeholder suggested that SIP credits be granted to 

States for adopting controls that minimize ORVR incompatibility emissions. One stakeholder 

stated that SIP credits should be granted for continuing to require pre-EVR standards or for 

requiring any part of CARB’s EVR program. Four stakeholders and one equipment vendor 

stated that EPA should grant SIP credits for States that require equipment such as P/V valves or 

add-on APCD. Three stakeholders indicated that they support granting SIP credits for improved 

monitoring of Stage II VRS. Two stakeholders suggested that SIP credits be granted for 

implementing Stage II VRS in new areas. One stakeholder contended that SIP credits should be 

granted to States for additional testing of Stage I equipment. Two stakeholders maintained that 

SIP credits should not be granted for the continuance of Stage II VRS after the widespread use 

date and for adopting Stage II VRS in new areas. 
DRAFT 2-07-06 

53

NESCAUM stated that they support SIP credits for maintaining Stage II VRS after the 

widespread use date but only if the emissions reductions achieved are greater than those 

emissions reductions achieved from ORVR. NESCAUM also stated support for granting SIP 

credits for improved monitoring and inspections of GDF, and the adoption of controls to 

minimize ORVR incompatibility emissions. NESCAUM further offered to assist the EPA with 

developing methods to enhance testing and inspection programs. 

The Connecticut DEP commented that EPA should grant SIP credits for States that 

require P/V valves and technology that reduces IEE, and for implementing Stage II VRS in new 

areas or moderate ozone attainment areas. 

The NJDEP suggested that EPA grant SIP credits for improved monitoring of Stage II 

VRS and for requiring P/V valves and mini-boots on vacuum assist VRS. NJDEP also indicated 

that SIP credits be granted for maintaining Stage II VRS after the widespread use date, but only 

if widespread use occurs before 100 percent fleet turnover of ORVR-equipped vehicles. 

The TCEQ maintained that EPA should mandate ORVR compatibility for States that 

choose to continue their Stage II VRS programs in order to be granted additional SIP credits. 

The Wisconsin DNR suggested that SIP credits be granted for maintaining Stage II VRS 

after the widespread use date, for conducting additional testing of Stage I equipment, the 

installation of a new technology that reduces emissions, and for requiring P/V valves. The 

Wisconsin DNR also recommended that SIP credits be granted to States for continuing to use 

pre-EVR standards or for using any part of CARB’s EVR program. 

Both API, NACS, and SIGMA stated that they do not support the granting of SIP credits 

for maintaining Stage II VRS after the widespread use date and for implementing Stage II VRS 

in new areas. These groups also stated that they do, however, support SIP credits for emissions 

reductions due solely to ORVR. API further noted that SIP credits should not be granted for 

implementing CARB’s EVR program, the installation of an ISD, or the installation of unihose 

equipment. 

2. Discussion and Recommendations 

Despite what some stakeholders believe about the need to eliminate Stage II VRS, we 

believe that there is merit to the idea to providing SIP credits for State and Local APCA that 

choose to retain Stage II VRS after the widespread use date. SIP credits related to continued use 

of Stage II VRS would depend on which definition EPA selects. For definition (c2), it is not 

clear what additional SIP credits would be available for continued use of Stage II VRS; for 

definition (c), additional SIP credits may be available for the difference in emissions levels with 

ORVR only and emissions levels with combined Stage II VRS and ORVR plus the 

incompatibility excess emissions. SIP credits could be provided for continued use of Stage II 

VRS and ORVR-compatible Stage II VRS for any of the definitions prior to the date associated 

with definition (c2). For States that use MOBILE6, the State emissions inventory may already 

account for ORVR emissions reductions. 

We believe that there is merit in granting SIP credits to State and Local APCA that 

choose to install other control measures after Stage II requirements are removed, such as UST 
DRAFT 2-07-06 

54

add-on APCD, P/V valves at GDF, improved parametric monitoring or ISD systems, dripless 

nozzles, operating training, and increased inspections. Additional control measures could be 

used at new facilities waived from requirements to install Stage II VRS, for GDF that remove 

Stage II VRS, or at other large-emitting GDF. We recommend, as stated previously, that EPA 

develop a guidance document, such as a CTG, discussing the control measures, efficiencies, and 

costs associated with each measure. Some control measures could be used in conjunction with 

continued Stage II VRS or could be used by GDF that remove the VRS systems. Preliminary 

monitoring shows that there may be additional fugitive emissions from the UST if the UST is not 

vapor tight. A P/V valve control measure should be accompanied by periodic UST pressure 

testing to confirm that fugitive emissions are not increasing due to pressurization of the UST and 

leaks. For balance systems and uncontrolled GDF (i.e., no Stage II VRS), the UST are more 

likely to remain at negative pressures for longer periods of time and pressurization of the UST 

may be less of an issue. UST with vacuum assist Stage II VRS will likely be at positive pressure 

for the majority of the time (generating additional fugitives when the UST is pressurized at 0 to 3 

in. w.c.), and these GDF could benefit from addition of a control measure to alleviate positive 

pressures. 

As there are some concerns regarding vapor leaks from UST due to pressurization and 

contamination of groundwater and soil (discussed later in this section), those additional control 

measures that alleviate pressurization of the UST should be given close consideration by States 

in the interim period before the widespread use date, especially for vacuum assist Stage II VRS. 

While we have not yet collected data on or tested the UST vent emissions for an 

uncontrolled GDF, these emissions levels should be quantified and the potential emissions 

reductions determined for UST control devices. We plan to conduct testing at an uncontrolled 

GDF that will include measurement of UST emissions (see section VI.D). 

We do not recommend requiring Stage II VRS in additional areas. It does not seem 

prudent to require a system that may be removed in a few years. Again, the cost analysis study 

to assess when new GDF would not be required to install Stage II VRS relative to the widespread 

use date may also address this issue. 

Additional control measures with respect to Stage I operations will be addressed in an 

area source standard for GDF. The Stage I source category will not be addressed here. 
DRAFT 2-07-06 

55

Table 8. Stage II State Implementation Plan (SIP) Credits Comment Summary 

Stakeholder Comment Summary Comment Detail

NESCAUM NESCAUM stated that they 

support the use of SIP credits 

to encourage States to 

maintain stringent vapor 

recovery programs to control 

both VOC and air toxics 

emissions. 

NESCAUM suggested that 

SIP credits only be granted 

when Stage II VRS achieves 

greater emissions reductions 

than those achieved by 

ORVR alone following the 

widespread use date. 

- NESAUM stated, “Once the use of Stage II controls does 

not garner any actual emission reductions, SIP credits 

should no longer be granted.” 

- NESCAUM also indicated that SIP credits should be 

granted for improved monitoring and inspections of 

GDF’s continuing to use Stage II VRS. 

- NESCAUM stated that States should be granted SIP 

credits for enhanced enforcement and compliance 

assistance efforts (such as enhanced monitoring and/or 

inspection programs) that will improve VRS efficiencies. 

- NESCAUM stated that EPA should investigate other 

means for maintaining program effectiveness, such as 

requirements to implement an equipment change-out 

schedule; 

- NESCAUM provided a copy of a report from Vermont’s 

Air Pollution Control Board that was used as a basis for 

such a program. 

- NESCAUM offered to work with EPA to develop 

methods to enhance testing and inspection programs and to 

quantify the benefits of these activities. 

- NESCAUM indicated that if ORVR incompatibility 

proves to be significant then incompatibility emissions 

should be considered new and not as the result of 

shortcomings of Stage II VRS design or the Stage II 

regulations adopted by a state’s SIP; states that adopt 

controls to minimize ORVR compatibility emissions 

should be given full SIP credit for those incremental 

reductions achieved. 

Connecticut DEP Connecticut DEP commented 

that EPA should allow SIP 

credits for States that require 

P/V valves and technology to 

reduce incompatibility excess 

emissions, and for States that 

choose to require Stage II 

VRS in new areas or 

moderate ozone 

nonattainment areas. 

Virginia VA supported SIP credits for 

areas that maintain Stage II 

VRS after widespread use has 

been achieved. 

NJDEP NJDEP stated that SIP credits 

should be granted for 

improved monitoring of 

Stage II VRS and other 

improvements such as 

requiring P/V valve and miniboots on vacuum assist VRS. 

- NJDEP stated that they have upgraded their Stage II VRS 

regulations to require annual testing of both Stage I and II 

systems and installation of P/V valves and mini-boots on 

nozzles (effective June 2, 2003). 

- NJDEP also believes that SIP credits should be granted if 

a state continues to require Stage II VRS after the 

widespread use date, if widespread use does not occur at 

100 percent fleet turnover. 
DRAFT 2-07-06 

56

Stakeholder Comment Summary Comment Detail

TCEQ TCEQ stated that ORVR 

compatibility should be 

mandated for those states 

choosing to maintain their 

Stage II VRS in exchange for 

SIP credits. 

Wisconsin DNR Wisconsin DNR recommends 

that EPA allow States to 

claim SIP credits for Stage II 

VRS that remain in operation 

after the widespread use date 

is reached. 

Wisconsin DNR also 

suggests that EPA provide 

additional SIP credits for 

additional testing of Stage I 

equipment. 

– The Wisconsin DNR, despite the language in Sections 

202(a) (6) and 182(b) (3), plans to retain Stage II VRS in 

nonattainment areas after the widespread use date is 

achieved. 

– Wisconsin DNR recommends that States that require 

Stage II VRS after the widespread use date is achieved, 

continue to require periodic testing and emissions 

monitoring. 

– Wisconsin DNR recommends that States be granted SIP 

credits for continuing to require pre-EVR standards and 

for requiring any part of the CARB Enhanced Vapor 

Recovery controls, such as ORVR compatibility. 

– Wisconsin DNR recommends that SIP credits be granted 

for any new technology installed at a GDF that produces 

verifiable emissions reductions, even if it is not part of the 

CARB EVR program. 

– Wisconsin DNR also recommends that SIP credits be 

granted for those States that require a P/V valve, if P/V 

valves prove to be beneficial. 

API API stated that after a state 

identifies the appropriate 

percentage of ORVR systems 

installed is equivalent to the 

Stage II in-use efficiency that 

is in a given SIP, SIP credits 

would then be appropriate for 

emissions reductions due 

solely to ORVR. 

API indicated that they do 

not support SIP credits for 

the continued use of Stage II 

VRS after the widespread use 

date, or implementing Stage 

II VRS in new areas. 

API stated that CARB’s 

program requiring a retrofit 

to existing GDFs to meet the 

new EVR is not necessary 

and as such, SIP credits 

should not be granted. 

– API cited a Tech Environmental Study5347 done in 

Tennessee that indicated the cost per ton of VOC 

emissions reductions increases from $10,000/ton in 2007 

to $26,000/ton in 2015. API added that when the cost of 

the State’s administration of the program is included that 

these costs rise to $11,000/ton and $29,000/ton, 

respectively.5448 

– API also cited the Tennessee proposal to implement 

Stage II VRS requirements in new counties. Tennessee 

decided against such requirements because Stage II was 

not a significant strategy and would become even less 

significant as more and more vehicles have ORVR control 

and larger activated carbon canisters. Also, Tennessee 

was not aware of any EAC [Early Action Compact] areas 

that actually used Stage II as a proposed strategy in the 

final analysis.5545 

– API stated that SIP credits should not be given for 

retrofitting existing equipment to accommodate CARB’s 

EVR program; both pre-EVR and EVR systems when 

properly maintained are certified to recover 95 percent of 

the refueling emissions. 

– API also indicated that SIP credits should not be granted 

for ISD installation or for requiring the installation of 

unihose equipment at GDFs. 

 

53 Cost Benefit Analysis for Stage II VRS Control in the Knoxville EAC Area. Tech Environmental (prepared for 

API). April 2004. 

54 Stage II Vapor Recovery System Operations & Systems Installations Costs. API Publication 1645. August 2002. 
DRAFT 2-07-06 

57

Stakeholder Comment Summary Comment Detail

RSA RSA stated that they believe 

it is appropriate to provide 

additional SIP credits related 

to the use of VRS. 

RSA stated that they support SIP credits for the following 

actions: 

1) Maintaining Stage II controls after the widespread use 

date as long as the VRS is a balance system or a vacuum 

assist VRS that has passed CARB’s strict [EVR] 

requirements. 

2) Stage II VRS (balance or CARB approved vacuum 

assist VRS) in new areas in order to reduce the transport of 

emissions to non-attainment areas or to provide additional 

health protection. 

3) Emissions reductions associated with improved 

monitoring. All States should be required to have an 

inspection and maintenance program in place. 

4) The installation of P/V valves. EPA should require P/V 

valves on all stations whether VRS equipped or not. 

5) VRS should be equipped with unihose dispensers in 

order to reduce the number of possible emissions points. 

6) Stage I testing should continue after widespread use and 

Stage II testing should continue for as long as the VRS are 

in operation. 

NACS and SIGMA NACS and SIGMA stated 

that they do not believe that 

SIP credits should be granted 

for continuing Stage II VRS 

after the widespread use date 

and for implementing Stage 

II in new areas. They did 

recommend that SIP credits 

be granted for emissions 

reductions attributed to 

ORVR. 

NACS and SIGMA commented, “Granting SIP credits 

after the widespread use date for enhancing or maintaining 

Stage II in existing areas or, certainly, for extending Stage 

II into new areas would be inconsistent with this 

Congressional policy choice. In fact, it would be illogical 

to grant SIP credits for Stage II controls that address the 

very same emissions for which credit is granted due to the 

use of ORVR. Of course, States should receive SIP credit 

for the emission reductions attributable to ORVR as Stage 

II is phased out.” 

NACS and SIGMA further noted that the substantial cost 

associated with installing new or enhanced Stage II are not 

justified by the diminishing marginal benefits that may be 

achieved by Stage II before the widespread use date 

arrives. 

ARID ARID indicated that SIP 

credits should be granted for 

installation of APCD systems 

and for integrated monitoring 

and local inspection and 

maintenance programs. 

ARID suggested that SIP credits could be given for the 

designation of BACT, MACT, or RACT for the use of 

APCD technology and/or inspection and maintenance 

programs. 

 55 Email communication, Wayne Davis, PhD, University of Tennessee and Prentiss Searles, American Petroleum 

Institute, March 31, 2004. 
DRAFT 2-07-06 

58

I. Enhanced Vapor Recovery (EVR) 

1. Comment Summary 

Two stakeholders expressed concern that CARB would no longer support or archive preEVR Stage II VRS. One stakeholder suggested that those vacuum assist Stage II VRS that pass 

CARB EVR approval would be much more complex and more expensive to install and maintain. 

One equipment vendor commented that CARB’s EVR program has certified several new Stage I 

VRS; full implementation of these new systems will result in decreased hydrocarbon emissions. 

One equipment vendor stated that a portion of CARB’s EVR program will result in decreased 

emissions, while some EVR requirements may actually increase fugitive emissions. One 

stakeholder recommended that States be granted SIP credits for continuing to require pre-EVR 

standards and for requiring any part of the CARB EVR, such as ORVR compatibility. 

The TCEQ indicated that they have relied on CARB to test and verify Stage II VRS but 

are now in the process of continuing to maintain pre-EVR standards without the assistance of 

CARB. API also indicated that they are concerned that CARB will no longer support or archive 

pre-EVR Stage II VRS and as such, areas without archived pre-EVR requirements could, by 

default, adopt EVR. API recommended that EPA archive the pre-EVR certifications and test 

procedures. 

Missouri DNR suggested that vacuum-assist Stage II VRS meeting CARB EVR 

requirements would be more complex and expensive to install and maintain. 

2. Discussion and Recommendations 

OPSG should consider adopting certain components of CARB’s EVR program, such as 

those that make the Stage II VRS controls compatible with ORVR as well as the ISD monitoring. 

All areas where Stage II VRS is required will continue with these controls until widespread use 

is achieved; some areas of the U.S. will no longer require Stage II VRS once widespread use is 

achieved and other areas will continue with Stage II VRS after the widespread use date. OPSG’s 

options include: (1) requiring no additional changes for Stage II VRS compatibility with ORVR 

through the widespread use date and phasing out Stage II VRS requirements once widespread 

use occurs, or (2) requiring that Stage II VRS be ORVR compatible prior to and following the 

widespread use date for areas that have and/or will retain Stage II VRS requirements. 

Whether or not to require ORVR compatible Stage II VRS will depend on which 

widespread use definition is selected and how early the date occurs. An early definition, such as 

definition (c) would not likely warrant additional conversion of vacuum assist Stage II VRS 

equipment, however, definition (a) would come later and the emissions benefits for ORVR 

compatible VRS may be worth the effort. The costs associated with this issue could be included 

as a component of the suggested cost analysis study for new GDF waivers. 

The MTBE issue is another consideration in deciding whether to require ORVR 

compatibility for Stage II VRS, and possibly has an effect in deciding on which definition. 

While some States have suggested that a later widespread use definition is better from their 

perspective, an earlier definition may help alleviate any MTBE issues associated with 

incompatibility of vacuum assist VRS with ORVR. 
DRAFT 2-07-06 

59

Another issue related to retaining the existing Stage II VRS requirements is that CARB 

has changed its program to require EVR compliant systems. Because other States often refer to 

CARB-certified equipment in their regulations and SIPs, once CARB removes the non-EVR 

certifications, this will be an issue for those States to deal with. 

Table 9. Enhanced Vapor Recovery (EVR) Comment Summary 

Stakeholder Comment Summary Comment Detail

TCEQ TCEQ indicated that they 

had previously relied on 

CARB to test and verify 

Stage II VRS equipment 

and that they are now 

attempting to continue preEVR standards without the 

assistance of CARB. 

- TCEQ stated that TCEQ and other States have relied on 

CARB to test and certify new Stage II VRS and peripheral 

equipment; however, since the implementation of EVR, 

CARB has decided not to certify or provide support for the 

previous VRS standard of 95 percent. 

- TCEQ stated that they are attempting to continue the preEVR standards while incorporating a requirement for ORVR 

compatibility. 

Wisconsin DNR Wisconsin DNR supported 

granting SIP credits for any 

implementation of EVR. 

Wisconsin DNR recommended that States be granted SIP 

credits for continuing to require pre-EVR standards and for 

requiring any part of the California Air Resources Board 

(CARB) Enhanced Vapor Recovery controls such as ORVR 

compatibility. The WDNR also recommends that EPA allow 

SIP credit for any new technology installed at GDFs that 

results in verifiable VOC emissions reductions, even if it is not 

part of the CARB EVR program. 

Missouri DNR Missouri DNR stated that 

their pressure data was the 

basis for CARB’s decision 

to limit UST pressures to no 

greater than + 0.25”wc as a 

CARB-EVR requirement. 

Missouri DNR stated that vacuum assist Stage II VRS that 

pass CARB EVR requirements will be significantly more 

complex and much more expensive to install and maintain. 

API API stated their concern that 

CARB will no longer 

support or archive pre-EVR 

Stage II VRS systems and 

equipment. 

API stated, “Meanwhile, most jurisdictions outside of 

California have specifically referenced and require CARB 

certified systems, equipment and testing procedures for their 

Stage I and/or Stage II regulations without qualification. If 

these individual jurisdictions fail to archive the pre-EVR 

references to the CARB certification program, these 

jurisdictions could, by default, adopt the CARB EVR 

program. Several states have recognized this dilemma and 

have archived the pre-EVR certifications and test procedures 

while allowing the voluntary installation of EVR systems. 

Another possible alternative to this dilemma is for the EPA to 

archive the pre-EVR certifications and test procedures.” 

VST VST stated that their newest 

hanging hardware, including 

the ENVIRO-LOC vapor 

recovery nozzles, exceeds 

CARB’s EVR front-end 

emissions standards by 90 

percent. 
DRAFT 2-07-06 

60

Stakeholder Comment Summary Comment Detail

Healy Healy commented that 

CARB’s EVR program has 

resulted in the certification 

of several new Stage I VRS 

and when fully implemented 

will reduce hydrocarbon 

emissions by 25 tons/day 

statewide. 

Healy indicated that they are the first to pass EVR Stage II 

testing and that EVR approved Stage I VRS have improved 

the ability to maintain leak tightness over long periods of time. 

EMCO Wheaton EMCO stated that some of 

the requirements of the 

CARB EVR program are 

“straightforward and will 

result in decreased 

emissions.” 

EMCO also noted that some 

of the EVR requirements 

may actually increase 

fugitive emissions. 

– EMCO suggested that the following EVR requirements will 

decrease emissions: dripless nozzles, liquid retention 

requirements, balance system component pressure drops, and 

leak tight connectors and fittings. 

– EMCO stated, “The pressure limit requirement of +0.25 

inches w.c. daily average, and +1.5 inches w.c. maximum 

requirement seeks to minimize pressure related fugitive 

emissions. These emissions may not actually exist in a 

properly constructed and tested system. These are the same 

emissions that are addressed by the phase I EVR requirements. 

The net result is a requirement that, in effect, chases potential 

fugitive emissions.” 

J. Monitoring/Inspections of GDF and Stage II VRS 

As discussed previously in this paper, the expected in-use control efficiency of Stage II 

VRS ranges from 56 to 90 percent, depending on the inspection frequency and the exemption 

levels. While Stage II control systems can achieve 95 percent or better control efficiency, in-use 

efficiency is shown to drop significantly without proper operation and maintenance. 

1. Comment Summary 

A few stakeholders commented that conducting more frequent inspections acts as a 

mechanism to improve Stage II VRS efficiency. One stakeholder indicated that they would like 

to work with EPA in developing methods to enhance testing and inspection programs. One 

equipment vendor commented that incentives should be developed to encourage and assist GDF 

owners and operators to install monitoring equipment that can help ensure that the VRS is 

operating properly. One stakeholder commented that ISD systems do not assure compliance, but 

instead identify failures at GDF that cause excess emissions. 

The Wisconsin DNR indicated that fugitive emissions are related to the deterioration and 

aging of GDF equipment and periodic testing/monitoring would help identify problems, which 

would lead to an improvement to in-use control efficiency. 

NESCAUM stated that they would like to work with the EPA in developing methods to 

enhance testing and inspection programs and suggested that EPA investigate other means for 

maintaining program effectiveness. NESCAUM enclosed a report that summarizes the results of 

a test program conducted by the Vermont Air Pollution Control Program; this test program was 

the basis for Vermont’s enhanced monitoring and inspection program (see section VI.B). 
DRAFT 2-07-06 

61

RSA recommended that a nationwide inspection program be developed to inspect Stage I 

VRS with P/V valves; this program would provide significant reductions in VOC and HAP at a 

low cost. 

Crompco, a provider of Stage II VRS compliance testing, indicated that there is a strong 

need to require more periodic testing on a basis more frequent than every 5 years. Crompco 

suggested an annual test. Crompco contends that as the testing frequency goes up, failure rates 

and emissions rates go down because problems are being identified and fixed; a well-maintained 

VRS helps control fugitive emissions from the system. 

Veeder Root suggested that most Stage II VRS failures are difficult to detect and may go 

uncorrected until the next inspection; however, an ISD can assist a GDF by alerting the GDF of 

potential problems. Veeder Root strongly recommended that incentives be made to GDF to 

encourage installation of ORVR compatible Stage II VRS and monitoring equipment to ensure 

proper operation. 

ARID stated that good housekeeping practices have not been present for GDF. ARID 

maintained that the use of an UST add-on APCD will give the GDF an incentive to ensure that 

the hardware is properly maintained. ARID further noted that continuous monitoring of UST 

pressure can alert GDF of potential problems. 

2. Discussion and Recommendations 

We believe that improved (and more frequent) monitoring, coupled with good operation 

and maintenance programs, results in emissions reductions. Use of ISD is a practical, 

inexpensive approach to better operation of GDF and VRS. EFPAG is currently collecting 

information regarding costs and that information will be forwarded to OPSG accordingly. We 

recommend that ISD be included as a control measure option for reducing emissions from GDF 

not only until the widespread use date is implemented but also continuing for GDF that do not or 

no longer have Stage II VRS. Control measures such as increased inspections, improved 

parametric monitoring, ISD, and operating training should be included in the control measures 

guidance for the States. These systems could be applied to continued use of Stage II VRS, new 

GDF that are waived of the requirements for Stage II VRS, or at uncontrolled GDF. 

Additional control measures with respect to Stage I operations will be addressed in the 

area source standard for GDF. The Stage I source category will not be addressed here. 

Table 10. Monitoring/Inspections of Stage II VRS Comment Summary 

Stakeholder Comment Summary Comment Detail

Crompco Crompco indicated that GDF 

should periodically survey the 

effectiveness of their VRS on a 

basis more frequently than every 

five years to reduce fugitive 

emissions. 

Crompco, a GDF inspection company, indicated that 

Stage II VRS is a very important component in 

controlling fugitive emissions from GDFs. Crompco 

provided data on GDF inspections (pressure decay tests) 

that showed: (1) inspections were important for ensuring 

that the Stage II VRS operate correctly, and (2) the more 

often inspections were conducted, the less frequently VRS 

equipment failures were found. 
DRAFT 2-07-06 

62

Stakeholder Comment Summary Comment Detail

CARB CARB stated that the ISD 

monitoring identifies failures 

that cause excess emissions but 

do not assure compliance. 

- CARB indicated that EPA mis-characterized ISD 

because ISD systems do not assure compliance, but 

instead identify failures at GDF that cause excess 

emissions. 

- CARB also stated that EPA implied that the ISD system 

automatically adjusts the V/L ratio; this is incorrect. The 

statement was taken from the February 4, 2000 staff 

report that discusses a specific sensor and not an ISD 

requirement. 

Wisconsin DNR Wisconsin DNR stated that 

periodic testing/monitoring 

provides an opportunity to 

improve the in-use efficiency of 

Stage II VRS. 

Wisconsin DNR commented, “The potential fugitive 

emissions are also related to deterioration and aging of the 

gasoline dispensing equipment and periodic 

testing/monitoring would help to identify problem 

components.” 

NESCAUM NESCAUM indicated that they 

would like to work with the EPA 

to develop methods to enhance 

testing and inspection programs 

and in quantifying the added 

benefits of such actions. 

NESCAUM submitted a report from the Vermont Air 

Pollution Control Program that was used as the basis for 

Vermont’s enhanced monitoring and inspection program. 

This report stated that testing was conducted at thirty two 

GDF to determine how well in-use GDF systems maintain 

compliance with performance standards and the level of 

effort required to bring GDF back into compliance. 

API API stated that EPA guidance 

indicates that in-use 

effectiveness is a function of the 

frequency of agency inspections. 

RSA RSA recommended that there be 

a nationwide inspection program 

of Stage I VRS with P/V valves. 

RSA stated, “We feel that implementation of certified and 

inspected Stage I VRS with PV valves nationwide would 

provide significant reductions in VOC and HAP 

emissions for the relatively low cost of these systems. 

They have the additional benefit of having overfill 

protection to reduce the emissions of liquid gasoline into 

the soil and waterways near stations as well as the 

pollution of soil and water from the deposition of vapors.” 

Veeder-Root Veeder-Root stated that most 

failures of VRS result in excess 

emissions, are difficult to detect, 

and typically go uncorrected 

until the next inspection takes 

place, which in most regions is 

only required annually. 

Veeder-Root suggested that ISD 

equipment can assist a GDF 

owner and/or operator in 

keeping their VRS in proper 

repair and operation. 

- Veeder-Root stated, “As components on the vapor 

recovery system wear out, drift out of calibration or fail, 

the ability of the system to capture and control vapor loss 

into the atmosphere is adversely affected and the 

collection efficiency at the vehicle may be reduced. For 

example, a station operating at 60% efficiency instead of 

the required 90% has the potential to emit an additional 

450 gallons of liquid gasoline per year into the 

environment.” 

- Veeder-Root has developed ISD equipment to meet 

CARB requirements. 

- Veeder-Root recommends that incentives be developed, 

“to encourage and assist GDF owners and operators to 

install ORVR-compatible Stage II VRS and Vapor 

Recovery Monitoring Equipment that can help insure that 

the Stage II VRS are operating at or above the levels they 

were originally designed to meet.” 
DRAFT 2-07-06 

63

Stakeholder Comment Summary Comment Detail

EMCO EMCO stated that oversight 

inspections have improved Stage 

II efficiency. 

EMCO commented, “However, oversight inspections are 

very different animals than planned obsolescence 

programs. The [equipment component replacement] 

proposal sketched out in paragraph 1 page 25 of the Issues 

Paper is simply not realistic. Date stamping and replacing 

components on a regular basis regardless of any known 

problem is unduly burdensome to the gas station 

operators.” 

ARID ARID noted that incentives for 

performing good housekeeping 

practices have not been present 

for GDF. ARID maintained that 

the use of an APCD and 

recovered product will give the 

GDF the proper incentive to 

ensure hardware is properly 

maintained and the vapor 

carrying components remain 

vapor tight. 

– ARID stated, “[t]he wise station owner will diligently 

maintain their APCD equipment with the confidence that 

their efforts and investment will be rewarded with saved 

product.” 

– ARID noted that continuous monitoring of UST 

pressure can alert a GDF of situations that warrant further 

investigation; a GDF can pinpoint the anomaly by 

examining typical leak sources, arranging a leak decay 

test, or arranging a detailed hardware inspection. 

– ARID suggested that useful monitoring information can 

be obtained with “macro” variables such as combined 

UST pressures and APCD run times; this type of 

monitoring is simple, elegant, robust, and cost-effective. 

K. Emissions Factors and Emissions Testing 

As discussed in the Issues Paper, the current average AP-42 emissions factor information 

is almost 20 years old and does not always account for more recent changes in gasoline 

composition. 

1. Comment Summary 

Three stakeholders and one equipment vendor commented on the need for new emissions 

factors. One stakeholder stated that they do not necessarily agree with API emissions factors and 

that they are working in conjunction with another partner on a test program to collect more 

information. 

TCEQ agreed with EPA that there needs to be new emissions factors for Stage I and II 

VRS. Wisconsin DNR and RSA noted a potential need for new VOC and HAP emissions 

factors for GDF. Wisconsin further suggested that EPA study and quantify fugitive emissions 

under various controlled and uncontrolled scenarios. RSA also commented that the emissions 

factor used to determine the spillage contributions for Figure 5 in the Issues Paper (Stage II 

VRS-only emissions levels) did not seem reasonable from CARB documents and Missouri DNR 

studies. 

ARID suggested that more testing be done to determine emissions factors for IEE from 

combined use of vacuum-assist Stage II VRS and ORVR, UST vent breathing and emptying 

emissions without Stage II VRS and with and without P/V valves, and fugitive emissions from 

Stage II VRS. 
DRAFT 2-07-06 

64

CARB stated that they do not necessarily agree with the emissions factors determined 

from API testing. CARB noted that they are working together in conjunction with API and the 

Western States Petroleum Association (WSPA) on a test program to collect more information. 

See section VI.C. 

2. Discussion and Recommendations 

Some of the variables known to affect emissions factors for GDFs include: ambient 

temperature, seasonal variation in gasoline Reid Vapor Pressure, gasoline throughput, vapor 

tightness of the GDF and VRS, and percentage of ORVR-equipped vehicles. We recommend 

updating the emissions factors based on all the data collected from stakeholders and additional 

emissions testing to be conducted by EPA and stakeholders. Only three emissions measurement 

tests were submitted by the stakeholders for traditional GDF, EPA is planning to conduct testing 

at two GDF, and Hertz is planning to conduct testing at their on-site GDF. These data include 

multiple emissions points in controlled and uncontrolled scenarios, and may be used to develop 

updated emissions factors. Based on continued discussions with stakeholders, it is clear that 

there is additional data that could be collected and included in these analyses. 

Table 11. Emissions Factors and Emissions Testing Comment Summary 

Stakeholder Comment Summary Comment Detail

CARB CARB stated that their staff does 

not necessarily agree with API 

emissions factors. 

CARB indicated that CARB and API are working 

together in conjunction with the WSPA on a test 

program to collect more information to help address 

differences in emissions data collected to date. 

TCEQ TCEQ indicated that they agree 

with the EPA regarding the need 

for new emissions factors for 

Stages I and II. 

TCEQ noted that allowing local inputs, such as liquid 

temperature and Reid Vapor Pressure, would be 

beneficial. 

Wisconsin DNR Wisconsin DNR noted the need 

for new VOC and HAP emissions 

factors for GDFs. 

Wisconsin DNR suggested that EPA study and 

quantify fugitive emissions under various controlled 

and uncontrolled scenarios. 
DRAFT 2-07-06 

65

Stakeholder Comment Summary Comment Detail

RSA RSA stated that there is a potential 

need for new emissions factors for 

VOC and HAPs. 

RSA also commented that the use 

of 0.5 of the AP-42 values for 

spillage emissions for the ORVR 

vehicles and 1.0 of the AP-42 

value for Stage II VRS seems 

unreasonable. Accurate values for 

the spillage must be used. 

RSA commented, “The HAPs emission factors 

should be related to the VOC emission factors 

relative to the composition of the gasoline and the 

temperature of the gasoline. CARB has done a 

number of studies analyzing SUMMA® canisters 

collected from various points in the vapor recovery 

systems to determine the relative concentrations of 

various components. MDNR has some similar data. 

The problem is that there is great variability of 

composition of gasoline, even the more strictly 

related RFG fuels. A good survey of data available 

should be made first to determine exactly what is 

appropriate for use for the systems and fuels being 

used in the areas of interest at the present and likely 

to be used in the next 10 years or so. It is also 

important to determine the actual emissions of the 

older ORVR vehicles upon fueling. It probably 

would be useful to do some specific VOC and HAPs 

measurements for these since it may be that the 

distribution of HAPs in relation to total VOC will be 

different for the ORVR than the VRS (i.e., the 

adsorption profile may well be different from the 

vaporization profile).” 

ARID ARID stated that they support the 

need for field testing to accurately 

quantify refueling–related 

emissions. 

ARID indicated there needs to be more testing to 

determine emissions factors for incompatibility 

excess emissions from vacuum assist Stage II and 

ORVR, UST vent breathing and emptying emissions 

from the UST without Stage II VRS and with and 

without P/V valves, and fugitive emissions from 

Stage II VRS. 

L. Exemptions for Rental Car Facilities 

1. Comment Summary 

One stakeholder requested a waiver from Stage II VRS requirements for rental car 

facilities whose vehicle fleet is comprised mostly of ORVR-equipped vehicles. Another 

stakeholder requested timely guidance from EPA on exemptions for rental car facilities 

dispensing 100 percent of their fuel to ORVR-equipped vehicles. 

TCEQ suggested that EPA provide timely guidance on exemptions for facilities, such as 

rental car facilities and car dealerships, dispensing 100 percent of their fuel to ORVR-equipped 

vehicles. 

Hertz requested a waiver from Stage II VRS. Hertz indicated that their current vehicle 

fleet is comprised of 99.3 percent ORVR-equipped vehicles and that this percentage would 

approach 100 percent by July 2006. 
DRAFT 2-07-06 

66

2. Discussion and Recommendations 

EPA is considering drafting and releasing a waiver guidance memorandum for rental car 

facilities for those facilities that can demonstrate that a significant portion of their vehicles are 

ORVR-equipped, that a significant portion of gasoline throughput is dispensed to ORVR 

vehicles, or that the emissions reductions achieved with ORVR controls are equivalent to the 

emissions reductions achieved with Stage II VRS. Because the majority of vehicles fueled are 

new vehicles with ORVR controls, the refueling emissions will be controlled by the ORVR 

canister. A similar waiver is also being considered for automobile manufacturing facilities. 

Table 12. Exemptions for Rental Car Facilities Comment Summary 

Stakeholder Comment Summary Comment Detail

TCEQ TCEQ requested that EPA provide 

guidance on exemptions from 

rental car facilities. 

TCEQ recommended that EPA provide timely 

guidance on exemptions for rental car facilities and 

car dealerships that dispense 100 percent of their 

fuel to ORVR-equipped vehicles. 

Hertz Hertz requested exclusion from 

Stage II VRS requirements 

because their vehicle fleet is 

largely comprised of ORVRequipped vehicles. 

Hertz stated that the widespread use definition 

should be applied to them. Hertz indicated that 

their vehicle fleet is comprised of 99.3 percent 

ORVR-equipped vehicles and that this percentage 

will approach 100 percent by July 2006. 

M. Stage I and II Equipment and UST Emissions 

1. Comment Summary 

One stakeholder commented that active tank management with membrane processors is 

the proper way to address excess emissions from the UST. Two equipment vendors commented 

that controlling the pressure of the UST will prevent fugitive VOC emissions from the Stage II 

VRS system. Other stakeholders maintained that processors utilized by vacuum assist Stage II 

VRS actually increase emissions of some pollutants (referring to incinerator controls). Two 

stakeholders suggested that CARB’s approach to estimating fugitive emissions actually penalizes 

a VRS that is vapor tight. One equipment vendor stated that required ORVR compatible Stage II 

VRS were more efficient and that its compatible equipment reduces emissions and maintains 

UST pressure. Another stakeholder suggested that P/V valves should be placed on all UST 

vents. 

The Missouri DNR suggested that a vacuum assist Stage II VRS that utilizes a 

combustion processor or incinerator actually increases emissions of polycyclic aromatic 

hydrocarbons (PAHs), as well as greenhouse gases, and nitrogen oxides; these pollutants would 

not have been emitted without the addition of an incinerator. RSA agreed with the Missouri 

DNR regarding an increase in emissions from utilizing a processor. RSA stated, “It does not 

make sense to create a problem when trying to solve another especially when there are other less 

polluting means available.” Missouri DNR also suggested that P/V valves be installed at all 

permitted Stage I GDF. 
DRAFT 2-07-06 

67

Costco Wholesale stated that prior to installing a membrane processor, their UST vented 

almost all day due to the incompatibility of ORVR and their vacuum assist VRS; after the 

membrane processor was activated, the vent episodes ceased. Costco also contends that 

membrane processors work with all UST systems (controlled and uncontrolled) and regardless of 

VRS type. 

API commented that vapor processors are expensive. Both API and STI stated that 

CARB’s method to calculate fugitive emissions has changed and now penalizes an UST system 

for being vapor tight. STI indicated that CARB and WSPA have drafted a testing protocol to 

help resolve this issue but as of yet, the protocol has not been finalized. 

Healy stated that ORVR compatible Stage II VRS are more efficient. Healy indicated 

that their compatible nozzles reduce emissions and that their Clean Air Separator (and UST addon APCD) acts as a pressurization system. 

VST suggested that by keeping the pressure of the UST below positive pressure, fugitive 

emissions from the UST would be minimized. VST further stated that they have several UST 

control systems, such as a membrane processor, that will control the pressure of the UST and 

recover gasoline vapor. 

EMCO maintained that P/V valves should be placed on all UST vents and that many 

vacuum assist Stage II VRS require an UST add-on APCD to deal with ORVR incompatibility. 

ARID contended that an APCD is the key factor in reducing the overall pressure of the 

UST. ARID also stated that a tight VRS system resulted in higher UST vent emissions, while a 

leaky VRS system resulted in higher fugitive emissions. 

2. Discussion and Recommendations 

We believe that VOC emissions from UST vents and leaks from USTs may be a major 

emission point at GDF, and as ORVR-equipped vehicles become more common, the emissions 

from UST at GDF with vacuum assist Stage II VRS are likely increasing. However, many of the 

stakeholders have not identified UST vents as a large source of VOC emissions. There have 

been some recent studies that indicate there are vapor leaks from USTs with resultant MTBE 

groundwater contamination. Some of the UST staff in the States (and at EPA’s Office of 

Underground Storage Tanks) believe that Stage II VRS, especially the vacuum assist systems, 

may be responsible for the vapor leaks. OUST has a current project underway to determine the 

causes and develop prevention measures for these vapor leaks. 

There are few data showing VOC emissions from USTs. Many certification tests have 

been conducted in California, yet there are little emissions measurement data for UST vents 

(CARB’s test procedure calculated UST fugitive emissions based on pressure data). Because 

CARB’s EVR program has requirements to control both tank pressures and UST vent emissions, 

the current CARB certification testing may not indicate any UST emissions problems. API’s 

comments seem to indicate that any UST emissions would be insignificant; however there are 

some data that have been supplied from vendors that show positive tank pressures lead to VOC 

UST emissions. Several vendors have suggested that GDF are emitting significant quantities of 

gasoline vapors and could save up to $2,000 per month by collecting these vapors. 
DRAFT 2-07-06 

68

We have observed one emissions measurement test in Florida in December 2004 where 

the tank pressure was greater than 3 in. w.c. for the entire test period. When the pressure reached 

3 in. w.c., the P/V valve popped open and vented emissions to the atmosphere. The P/V valves 

are required by Stage I (gasoline tank refilling) provisions in ozone nonattainment areas. If tank 

pressures are positive, then there will be fugitive leaks either through small cracks, improper 

fittings, etc. or through the UST vent. 

As mentioned above, staff that work with USTs regularly think that pressurized tanks 

lead to vapor leaks. Gary Lynn of the New Hampshire DEP said that he thinks all USTs leak.5846

We recommend the use of P/V valves on UST vents nationwide for additional HAP 

control. 

Table 13. Stage I and II Equipment and Underground Storage Tank (UST) Emissions 

Comment Summary 

Stakeholder Comment Summary Comment Detail

Missouri DNR Missouri DNR stated that 

vacuum assist Stage II VRS 

that use a combustion 

processor (incinerator) 

increase emissions. 

Missouri DNR also 

suggested that the EPA 

require permitted Stage I 

GDF to install P/V valves. 

– Missouri DNR suggested that combustion processors 

increase emissions of PAHs as well as green house 

gases, and nitrogen oxides that would not otherwise be 

emitted. 

– Missouri DNR stated that Stage I is inexpensive to 

install and maintain, and would significantly reduce the 

VOC, HAPs, HC and MTBE issues. 

Costco Costco indicated that they 

believe membrane 

technology virtually 

eliminates vent and fugitive 

emissions from GDF and is 

the right way to manage 

UST pressure. 

– Costco stated, “[W]e believe that membrane 

processors work with all UST systems, whether Stage II 

is balance, vac assist, or absent. Allowing tank systems 

to ‘breathe’ to atmosphere (as all do without tank 

pressure management, especially at night) is to face the 

uncomfortable decision of how much pollution is OK. 

We prefer no pollution at all if the technology is 

available to prevent it. With membranes, virtually all 

vent and fugitive emissions are eliminated.” 

– Costco commented, “We do not believe there is any 

long-term future for Stage II vapor recovery, but we feel 

that all stations should be built to actively manage their 

tank pressures to prevent venting.” 

API API stated that vapor 

processors are expensive. 

API also stated that the 

approach CARB uses to 

calculate fugitive emissions 

has changed significantly 

and now penalizes an UST 

system for being vapor tight. 

API criticized CARB’s EVR cost data for vapor 

processors. API stated that this data is unrealistically 

low. 

 

58 Teleconference with EPA, February 2005. 
DRAFT 2-07-06 

69

Stakeholder Comment Summary Comment Detail

STI STI stated that CARB’s 

methodology for estimating 

fugitive emissions penalizes 

Stage II VRS that are more 

vapor tight. 

STI indicated that CARB and the WSPA have drafted a 

testing protocol to help resolve this issue and that the 

protocol has not yet been finalized. 

Healy Healy indicated that 

required ORVR compatible 

Stage II systems are more 

efficient. 

– Healy stated that their Stage II VRS nozzles reduce 

emissions through reduced spillage, fewer drips, no 

“spitting”, clean fills at 10 gallons per minute; the 

nozzles also reduce “topping off” spills and potential for 

fires. 

– Healy provided data to demonstrate that their Clean 

Air Separator prevents the ullage space pressure from 

exceeding CARB’s maximum average positive pressure 

of 0.25 in. w.c. 

VST VST maintained that 

controlling the pressure of 

the tank (and keeping it 

below positive pressure) 

will prevent fugitive 

emissions of VOCs from the 

system. 

– VST commented on UST emissions and how they 

result from the pressure of the tank and fuel delivery 

system. 

– VST has several systems that will control the pressure 

in the tanks and recover the VOC emissions such as a 

membrane processor. VST stated that new technologies 

will provide the ability to utilize ORVR systems and 

Stage II systems simultaneously. 

RSA RSA maintained that 

vacuum assist Stage II VRS 

equipped with processors do 

not solve the pollution 

problem because the 

processor causes emissions 

of other pollutants that 

would not have been emitted 

without the processor. 

RSA stated, “It does not make sense to create a problem 

when trying to solve another especially when there are 

other less polluting means available.” 

EMCO EMCO stated that P/V 

valves should be placed on 

all UST vents. 

EMCO also noted that 

vacuum assist Stage II VRS 

often require add-on control 

devices to deal with the 

incompatibility emissions 

problem. 

EMCO referenced a processor cost of $30,000. 

ARID ARID stated that an APCD 

is key to reducing the 

overall UST tank pressure. 

– ARID commented that an excess vapor generation rate 

is present in the UST and that excess vapor within the 

UST will result in a pressure increase; a tight system 

will yield higher vent emissions, while a leaky system 

will yield higher fugitive emissions. ARID notes that an 

air pollution control device reduces the overall storage 

tank pressure while at the same time capturing and 

recovering vent emissions. 

– ARID stated that testing performed at one of their test 

sites demonstrated that their PERMEATOR significantly 

reduced fugitive emissions; the UST vent without the 

PERMEATOR on resulted in fugitive emissions by 

more than 200 times. 
DRAFT 2-07-06 

70

N. MTBE Groundwater Contamination from UST 

1. Comment Summary 

One stakeholder provided documentation that contends the UST leaks are from vapors 

that are released through the innate pressurization of the USTs by the vacuum assist Stage II 

VRS. Two stakeholders commented that with the removal of Stage II VRS, contamination of 

groundwater caused by fugitive emissions from the pressurized VRS at GDF would cease. One 

stakeholder suggested that the MTBE issue is a good example of what can go wrong while fixing 

one problem but not paying attention to the effects of the proposed solution. One equipment 

vendor stated that EPA should address the MTBE problem by requiring the use of CARB 

certified ORVR compatible Stage II VRS. 

The Missouri DNR stated that New Hampshire is experiencing MTBE groundwater 

contamination. Missouri DNR submitted an article that maintained that the leaks are caused by 

vapors that are released through the innate pressurization of the UST by vacuum assist Stage II 

VRS. 

Both API and BP stated that the removal of Stage II VRS in favor of ORVR would help 

minimize groundwater contamination. API further stated that they have a group of experts that 

are examining the groundwater contamination issue. API and BP recommended that more 

research be done to identify the significance and associated circumstances of groundwater 

contamination before any widespread regulatory actions are taken. 

Healy stated that New Hampshire has been monitoring a large percentage of Stage IIequipped GDF to examine the extent of groundwater pollution. He indicated that New 

Hampshire’s findings indicate that 129 out of 300 GDF show unacceptable levels of MTBE. 

Healy suggested that the contamination was caused from vacuum assist Stage II VRS due to 

ORVR incompatibility. Healy recommended that EPA make every effort to address this issue by 

requiring GDF to use CARB-certified ORVR compatible Stage II VRS. 

2. Discussion and Recommendations 

UST fugitive emissions are caused by pressurization of USTs. While fugitive emissions 

may occur when pressurization occurs for either balance or vacuum assist, balance systems seem 

to minimize the amount of time the UST is at positive pressure and therefore may minimize 

fugitive emissions. Vacuum assist systems, however, may cause pressurization of the UST 

during operating hours in addition to off hours. Measures that can be taken to reduce the 

pressurization of UST vacuum assist systems should be studied and considered. These may 

include some components of the EVR program that make vacuum assist Stage II VRS 

compatible with ORVR vehicles. The use of MTBE as an oxygenate in gasoline has resulted in 

detections of MTBE in drinking water. In the past, it was frequently leaking USTs or spills that 

caused the contamination of soil and water at and near the GDF site. However, with 

implementation of stricter UST regulations, the contamination of soil and water is thought to be 

caused by vapor leaks from the UST. The CAA requires that RFG contain 2 percent oxygen by 

weight, and over 85 percent of RFG contains MTBE and approximately 8 percent contains 
DRAFT 2-07-06 

71

ethanol.5647 Some States have banned MTBE use in gasoline, and MTBE may be replaced in 

favor of other oxygenates such as ETBE, TAME, TAEE, DIPE, ethanol, and TBA.5748 The 

changes in the gasoline composition may eliminate the MTBE in gasoline, however, because the 

other oxygenates have similar but not identical chemical characteristics, they may simply result 

in a shift in the contaminant compound found in soil and groundwater near GDF.56 The effect of 

the other oxygenates may not yet be known but fugitive emissions certainly should be minimized 

as a precaution regardless of the next generation of oxygenates. In any case, EPA could 

implement requirements to minimize fugitive emissions, such as increased testing of vapor 

tightness and reducing pressurization of tanks, especially from vacuum assist Stage II VRS. 

Table 14. MTBE Groundwater Contamination from UST Comment Summary 

Stakeholder Comment Summary Comment Detail

Missouri DNR Missouri DNR indicated that New 

Hampshire is experiencing MTBE 

ground water contamination. 

Missouri DNR provided an article that contends that 

the leaks are caused by vapors that are released 

through the innate pressurization of the UST by the 

vacuum assist VRS. 

API API stated that discontinuing Stage 

II VRS in favor of ORVR will help 

eliminate groundwater 

contamination issues. 

API further stated that they have a 

group of experts working on the 

groundwater contamination issue 

and believe more needs to be done 

to identify the significance and 

circumstances related to 

groundwater contamination before 

any widespread regulatory actions 

are taken. 

API commented that there have been some isolated 

incidents of groundwater contamination allegedly 

from UST system vapor leaks. API stated that some 

recent papers have preliminary data to bolster such 

allegations; however these papers also 

acknowledged the need for further research on this 

matter. 

BP BP stated that with the removal of 

Stage II VRS in favor of ORVR, 

contamination of groundwater 

caused by fugitive emissions from 

the pressurized VRS at GDF would 

cease. BP also acknowledged the 

need for further research on the 

groundwater contamination issue. 

BP commented that API and member companies are 

concerned about the allegation that GDFs are 

causing MTBE contamination of groundwater; they 

are currently working on this issue. BP also 

cautioned, “... given that this forum includes 

regulators and rule makers, more needs to be done 

before taking any widespread regulatory actions.” 

RSA RSA stated that the MTBE issue is a 

good example of what can go wrong 

when not addressing all the potential 

pollution problems while trying to 

solve another problem. 

RSA commented, “It does not make sense to create a 

problem when trying to solve another especially 

when there are other less polluting means available.” 

 

56 Achieving Clean Air and Clean Water: The Report of the Blue Ribbon Panel on Oxygenates in Gasoline. EPA 

Publication No. EPA420-R-99-021. September 15, 1999. 

57 Predicted Ground Water, Soil and Soil Gas Impacts from U.S. Gasolines, 2004 First Analysis of the Autumnal 

Data. EPA Publication No. EPA 600/R-05/032. February 2005. 
DRAFT 2-07-06 

72

Stakeholder Comment Summary Comment Detail

Healy Healy shared information from New 

Hampshire that indicated that some 

GDF are showing levels of MTBE 

that are unacceptable. Healy 

suggested that a vacuum assist Stage 

II VRS will most likely be polluting 

the soil and ground water due to 

ORVR vehicle refueling. Healy 

stated that EPA should apply every 

effort to address groundwater 

contamination by requiring the use 

of CARB certified ORVR 

compatible Stage II VRS. 

- Healy stated that New Hampshire has been 

monitoring a large percentage of Stage II equipped 

GDF to determine the extent of groundwater 

pollution. New Hampshire’s findings showed that 

129 out of 300 GDF showed unacceptable levels of 

MTBE. 

- Healy further stated that almost all the GDFs with 

unacceptable MTBE levels were vacuum assist 

Stage II VRS and no ORVR compatible systems 

were on the list. 

- Healy also indicated that studies performed by the 

University of California, Davis confirmed that 

MTBE vapor releases are strongly associated with 

vacuum assist Stage II VRS. 

- Healy maintained that the source of this pollution 

is a build-up of positive pressure in the ullage space 

of the UST. 

VI. Emissions Monitoring and Testing Data 

A. Previous Data Collected by EPA 

Prior to the public meeting in September 2004, EPA collected and analyzed data from 

several studies conducted to evaluate excess emissions from the refueling of ORVR-equipped 

vehicles at GDF with Stage II VRS. Each data source and the tests conducted are discussed, the 

key results and conclusions presented in the data sources are summarized, and a large summary 

table of all the data is presented. The table is organized to identify the actual measurements 

conducted and results reported in the study. 

Emissions may occur (and may be measured or calculated) at numerous points within the 

system. CARB’s Stage II VRS certification test method, TP-201.2, addresses making 

measurements or calculating emissions from several points in the system. The measurement 

points include: 

1. Emissions at nozzle/vehicle interface (“fillpipe” emissions), 

2. VOC’s returned through the vapor passage of the hose, 

3. Emissions from the UST P/V valve, 

4. Emissions from the assist processor (not applicable in these studies), and 

5. Calculated pressure-related fugitives based on UST pressure measurements. 

(EPA defines refueling emissions as the evaporative loss emissions during refueling, as 

well as emissions from spillage. For the purposes of the discussions below, spillage emissions 

are not addressed and any reference to “refueling emissions” does not include spillage. The 

emissions data generally are reported as lb VOC/1,000 gallons dispensed. In the actual reports, 
DRAFT 2-07-06 

73

both lb /1,000 gallons dispensed and grams of VOC per gallon (g/gal) dispensed were used; this 

often got confusing as the authors switched back and forth. The data in the summary table are 

presented in lb/1,000 gallons.) 

1. CARB’s Preliminary Test Report, June 1999 (GDF) 

These tests were conducted in August/September 1998 at two GDF with vacuum assist 

Stage II VRS to quantify excess emissions from vapor growth; each GDF had a different type of 

vacuum assist system. At the time of the tests, these two types of systems represented 80 percent 

of VA systems in CA and dispensed 55 percent of the gasoline purchased. The emissions from 

the Stage II VRS were determined from direct measurement of P/V valve emissions and 

calculation of fugitive emissions based on UST pressure readings. CARB did not measure or 

attempt to quantify the emissions at the nozzle/fill pipe interface (“fillpipe emissions”) during the 

study. The testing consisted of two phases: (1) “baseline” normal operations, and (2) simulated 

ORVR. Because ORVR vehicles were not prevalent when the tests were done, the refueling of 

ORVR was simulated by modifying the dispensers to ingest ambient air; an ORVR population of 

approximately 40 to 45 percent was simulated. 

Negligible emissions were emitted from the P/V valve, and UST fugitive emissions 

occurred due to leaks. Excess emissions, which are based on pressure-related fugitive 

calculations, also occurred when refueling with the simulated ORVR scenario. Table 15 

includes a detailed summary of the data for each emissions point. CARB used these data to 

establish excess emissions factors for refueling of ORVR-equipped vehicles in combination with 

vacuum assist Stage II VRS of 0.86 lb/1000 gal for the Gilbarco system and 0.06 lb/1000 gal for 

the Dresser Wayne system with the P/V valve in place. Operation without the P/V valve was 

considered atypical and these data were not used in CARB’s final analyses. 

2. Phase 1 of API’s ORVR Compatibility Study (GDF) 

These tests were conducted at a GDF in California with a vacuum assist (Gilbarco) Stage 

II VRS to determine the amount of excess emissions from refueling ORVR-equipped vehicles. 

The tests were conducted using summertime RFG (RVP 7.0 psi) and two types of nozzles. In 

Test 1, refueling was conducted with standard vacuum assist nozzles for a 100-car matrix. Test 2 

also included a 100-car matrix, however, nozzles with “miniboots” were used to limit the influx 

of ambient air during refueling. The testing was conducted using CARB’s certification test 

procedure TP201.2. These data are summarized in Table 15. 

The overall pressure-related emissions for Test 1 (with the standard vacuum assist 

nozzle) were 1.38 lb/1,000 gal and for Test 2 (with the miniboot nozzles) were 0.494 lb/1,000 

gal. Therefore, the miniboot showed a reduction in pressure-related emissions of 0.886 lb/1000 

gal (or a 64 percent reduction). The effects of ORVR versus non-ORVR vehicles on UST 

pressures and UST vent emissions due to interferences from vehicles simultaneously refueling at 

other pumps connected to tanks could not be differentiated (i.e., quantified). 

The emissions from the vehicle fillpipe/nozzle interface were measured, and the test 

results showed that ORVR controls reduced emissions from the interface by 0.31 lb/1,000 gal. 

Therefore, it was concluded that the value CARB determined for the excess emission factor due 
DRAFT 2-07-06 

74

to vapor growth in the UST (0.86 lb/1,000 gal, see above) should be offset accordingly; i.e., total 

excess emissions should be 0.86 lb/1,000 gal - 0.31 lb/1,000 gal, or 0.55 lb/1,000 gal. 

3. Phase 2 of API’s ORVR Compatibility Study (Outside) 

These tests were outdoor tests conducted at a research facility using a 3,000 gal UST that 

contained 1,000 gal of gasoline. The gasoline was a summer grade oxygenated fuel with a RVP 

of 7.8 psi. Six refueling tests were conducted on 3 vehicles (two with ORVR and one without 

ORVR). The UST emissions from the P/V valve and the pressure-related fugitives were 

measured; the system was demonstrated to be leak free prior to testing, and a fugitive leak rate 

was simulated, and controlled, using a calibrated needle valve. The fugitive emissions measured 

while refueling ORVR and non-ORVR vehicles were compared to determine the incompatibility 

excess emissions. In addition, the pressure-related fugitives were measured and compared to 

those predicted by the CARB calculations. 

For the standard nozzle tests, the pressure-related excess emissions were calculated to be 

0.72 lb/1000 gal. The fillpipe emissions for ORVR-equipped vehicles were 0.39 lb/1,000 gal 

less than for non-ORVR vehicles (represents a 91 percent reduction). The adjusted (“net”) 

ORVR excess emissions were 0.33 lb/1,000 gal (i.e., pressure-related excess emissions minus the 

savings at the fill pipe, equal to 0.72-0.39). If these corrections are used on the data generated 

from MOBILE6, the correct excess emission factor to use would be 0.42 lb/1,000 gal (not 0.33 

lb/1,000 gal) because MOBILE6 already accounts for some of the fillpipe reductions achieved by 

ORVR-equipped vehicles by using a 98 percent control efficiency for ORVR rather than the 95 

percent efficiency used for Stage II VRS. 

For the miniboot nozzle tests, the pressure-related excess emissions were calculated to be 

zero (-0.008 lb/1000 gal). It was shown that the fillpipe emissions for ORVR-equipped vehicles 

were less than for non-ORVR vehicles. The adjusted (“net”) ORVR excess emissions were -0.39 

lb/1000 gal; i.e., a decrease in emissions [zero pressure-related excess emissions minus the 

savings at the fill pipe is equal to a reduction of 0.39 lb/1000 gal]. 

4. Phase 2 of API’s ORVR Compatibility Study (SHED) 

The emissions testing was conducted in Sealed Housing for Evaporative Emissions 

(SHED). A total of 36 refueling tests using procedures similar to the federal ORVR certification 

test were conducted for three vehicles (two with ORVR and one non-ORVR). During these 

tests, the impacts of the RVP, temperature, the A/L ratio, and the type of ORVR equipment were 

determined. 

First, the ORVR performance was checked (validated) with a baseline certification. The 

tests were conducted to investigate the impact of several factors, including: 

(1) RVP: The tests were conducted with an RVP of 7.1 and 7.8 psi; 

(2) Temperature difference: Three summertime temperature scenarios were used: one 

vapor growth and two vapor shrinkage scenarios. The scenarios included varying the 

temperature of the fuel dispensed and the temperature of the vehicle gasoline tank. 

(3) A/L ratios: standard nozzle and the miniboot. 
DRAFT 2-07-06 

75

(4) Type of ORVR equipment: recirculation or not. 

The fillpipe emissions for ORVR and non-ORVR vehicles fall within the range of values 

measured in the Phase 1 and Phase 2 (outdoor tests). The fillpipe emissions for ORVR-equipped 

vehicles were 0.46 lb/1000 gal less than for the non-ORVR vehicles. For ORVR-equipped 

vehicles, fillpipe emissions were not sensitive to changes in the RVP, the temperature differences 

between the vehicle tank and the dispensed gasoline, and the A/L ratio. There was, however, a 

positive correlation between the fillpipe emissions and the vehicle tank temperature. 

For non-ORVR vehicles, there was a positive correlation of the fillpipe emissions with 

the RVP, a negative correlation of the fillpipe emissions with A/L ratio, and a negative 

correlation of the fillpipe emissions with delta T, as assumed in MOBILE 6. The fill-pipe 

emissions for the miniboot (A/L ratio of 0.95) were greater than (approximately double) the 

fillpipe emissions with the standard nozzle (A/L ratio of 1.15). The emissions are greater for the 

vapor growth scenario (temperature of the fuel in the vehicle gasoline tank is less than the 

temperature of the fuel being dispensed). For the ORVR-equipped vehicles, the puff emissions 

(the puff of emissions when the gas cap is removed) are the same order of magnitude as the 

fillpipe emissions; the same is true to non-ORVR vehicles. 
76 

Table 15. Summary of Previous Data Collected by EPA: Test Data for Excess Emission

Data source

Unit type/ 

test conditions

Fillpipe 

emissions 

(a) (b)

P/V Valve 

emissions 

(c)

Calculated 

pressure -

related 

fugitives 

(leaks) 

(d)

Total 

pressure -

related 

emissions 

(e = c+d)

Total 

refueling 

emissions 

(f =b+c+d)

Excess 

emission 

due to 

ORVR 

incomp. (g)

ORVR 

emission 

reduction at 

fill pipe 

(h)

Adjuste

excess 

emissio

due to 

ORVR 

incomp

(i)

Gilbarco VA Baseline: 

CARB [1] 0.396 Scenario 1 

Gilbarco VA ORVR: 

Not measured Negligible 

 0.782 0.386

Not 

measured 

 

Dresser Wayne Baseline: 

CARB [1] 0.028 Scenario 2 

Dresser Wayne ORVR: 

Not measured 

Negligible. 

 0.0524 0.0244 Not 

measured 

 

Dresser Wayne (without  P/V valve) Baseline: 

CARB [1] 0.026 0.026 Scenario 3 

Dresser Wayne (without  P/V valve) ORVR: 

Not measured Negligible 

0.289 0.289 0.263 Not 

measured 

 

CARB Gilbarco VA 

Dresser Wayne 

0.86 0.06

 

Gilbarco VA Standard nozzle (OPW 11VA1); non-ORVR 

API [2] 0.42 Test 1 

Gilbarco VA Standard nozzle (OPW 11VA1); ORVR vehicles 

0.11 

0.823 0.557 1.38 

 Not measured 0.31 

(73% less 

than nonORVR) 

 

Gilbarco VA With “miniboot” (OPW 12VW); non-ORVR 

0.42 

API [2] Test 2 

Gilbarco VA With “miniboot” (OPW 12VW); ORVR vehicles 

0.11 

0.008 0.484 0.494 

 Not measured 0.31 

(73% less 

than nonORVR) 

 
77 

Data source

Unit type/ 

test conditions

Fillpipe 

emissions 

(a) (b)

P/V Valve 

emissions 

(c)

Calculated 

pressure -

related 

fugitives 

(leaks) 

(d)

Total 

pressure -

related 

emissions 

(e = c+d)

Total 

refueling 

emissions 

(f =b+c+d)

Excess 

emission 

due to 

ORVR 

incomp. (g)

ORVR 

emission 

reduction at 

fill pipe 

(h)

Adjuste

excess 

emissio

due to 

ORVR 

incomp

(i)

Outdoor test 5; Standard nozzle non-ORVR 

1.53 

(check) 

0 (Measured) 

0.022 

(Measured) 

0.022 

 NA 

Outdoor test 1; Standard nozzle ORVR vehicle with recirc. 

0.024 0 (Measured) 

0.918 

(Measured) 

0.918 

 0.896 

Outdoor test 3; Standard nozzle ORVR vehicle without recirc. 

0.026 

(check) 

0 (Measured) 

0.229 

(Measured) 

0.229 

 0.207 

API[3] 

Standard nozzle ORVR vehicle, wgt. average (calculated) 

0.025 0.745 (k) 0.72 (k) 0.39 (m) 

(91% less 

than nonORVR) 

0.33 

API[3] Outdoor test 6; 

Miniboot; non-ORVR 

2.11 0 (Measured) 

0.011 

(Measured) 

0.011 

 NA 

 Outdoor test 2; 

Miniboot; ORVR vehicle with recirc. 

0.002 0 (Measured) 

0.004 

(Measured) 

0.004 

 - 0.007 

 Outdoor test 4; 

Miniboot; ORVR vehicle without recirc. 

not available 0 (Measured) 

0.002 

(Measured) 

0.002 

 - 0.009 

 Miniboot; 

ORVR vehicle, wgt average (calculated) 

 0.003 (k) -0.008 (k) 0.39 (m) 

(91% less 

than nonORVR) 

-0.39 

i.e., zer
78 

Data source

Unit type/ 

test conditions

Fillpipe 

emissions 

(a) (b)

P/V Valve 

emissions 

(c)

Calculated 

pressure -

related 

fugitives 

(leaks) 

(d)

Total 

pressure -

related 

emissions 

(e = c+d)

Total 

refueling 

emissions 

(f =b+c+d)

Excess 

emission 

due to 

ORVR 

incomp. (g)

ORVR 

emission 

reduction at 

fill pipe 

(h)

Adjuste

excess 

emissio

due to 

ORVR 

incomp

(i)

SHED Standard nozzle Non - ORVR 

0.32 

SHED Standard nozzle ORVR  with recirc. 

0.057 

SHED Standard nozzle ORVR without recirc 

0.007 

API[4] 

SHED Standard nozzle ORVR Vehicle wgt avg. (calc) 

0.045 0.275 

API[4] SHED 

Mini-boot Non - ORVR 

0.69 

 SHED 

Mini-boot ORVR with recirc 

0.054 

 SHED 

Mini-boot ORVR without recirc 

0.007 

 SHED 

Mini-boot ORVR Vehicle Wgt Avg. (calc) 

0.041 0.649 
79 

Data source

Unit type/ 

test conditions

Fillpipe 

emissions 

(a) (b)

P/V Valve 

emissions 

(c)

Calculated 

pressure -

related 

fugitives 

(leaks) 

(d)

Total 

pressure -

related 

emissions 

(e = c+d)

Total 

refueling 

emissions 

(f =b+c+d)

Excess 

emission 

due to 

ORVR 

incomp. (g)

ORVR 

emission 

reduction at 

fill pipe 

(h)

Adjuste

excess 

emissio

due to 

ORVR 

incomp

(i)

SHED Vehicle 3 Non - ORVR 

PUFF (n) 

0.321 

SHED Vehicle 1 ORVR with recirc 

PUFF (n) 

0.030 

API [4] 

SHED Vehicle 2 ORVR without recirc 

PUFF (n) 

0..007 

API [4] Vehicle 1: ORVR 

Certification 

0.017 

[0.008] 

API[4] Vehicle 2: ORVR 

Certification 

0.002 

[0.001] 

 EPA Standard for 

ORVR 

0.44 

[0.20] 

(Includes 

spillage) 
80 

Data source

Unit type/ 

test conditions

Fillpipe 

emissions 

(a) (b)

P/V Valve 

emissions 

(c)

Calculated 

pressure -

related 

fugitives 

(leaks) 

(d)

Total 

pressure -

related 

emissions 

(e = c+d)

Total 

refueling 

emissions 

(f =b+c+d)

Excess 

emission 

due to 

ORVR 

incomp. (g)

ORVR 

emission 

reduction at 

fill pipe 

(h)

Adjuste

excess 

emissio

due to 

ORVR 

incomp

(i)

NOTES

a Refueling emissions = fill pipe displacement + spillage per EPA definition; spillage not addressed in these data 

b Fill pipe emissions = fill pipe displacement emissions c P/V vent emissions = emissions from UST vent pressure/vacuum valve d Calculated pressure related (PR) fugitive emissions from VRS leaks per CARB calculation method e Total pressure related emissions = P/V vent emissions + PR fugitives f Total refueling emissions = total refueling emissions by CARB test method = Fill pipe displacement + P/V vent emissions + calculated PR fugitives (spillage estima

performance standard of nozzle?) 

g Excess emissions due to ORVR incompatibility = total pressure related emissions for ORVR - total pressure related emissions for non-ORVR vehicles. Note: the A

emissions of pressure-related fugitives separately from P/V emissions 

h ORVR emission reductions at fill pipe = measured fill pipe displacement emissions for non-ORVR vehicles - measured fill pipe displacement emissions for ORVR 

i Total adjusted excess emissions = pressure related excess emissions due to ORVR incompatibility - ORVR emissions reductions achieved at fill pipe 

Note: the API report refers to this as “total incompatibility emissions” j Average hydrocarbon concentration in the VRS return line. k Weighted average of ORVR with and without recirculation; assumes 75% of ORVR vehicles have recirculation. m Average of Phase 1 (in-field) tests and SHED tests n PUFF = puff of emissions that occur when gas cap is removed; measured quantity normalized to gallons dispensed 

p Measured values are from test simulation of 40 to 45% ORVR vehicles; calculated emissions factors are extrapolated; divide measured Gilbarco value by 0.45; div

value by 0.39 [CARB Enhanced Vapor recovery ISOR, February 2000, Appendix D; CARB Enhanced Vapor Recovery Technology Review, October 2002] 

NA = Not Applicable All emission units are lb/1000 gals dispensed or [g/gal] unless otherwise noted. 
DRAFT 02-07-06

81

B. Data Provided by Stakeholders 

Several stakeholders provided monitoring and testing data to assist us in understanding: 

(1) the sources of emissions at GDF, and (2) the impact UST pressure has on emissions at GDF. 

We received data from multiple States, GDF operators, and equipment vendors. We also 

received data for vehicle fueling operations at automobile manufacturing facilities. These data 

included: 

# Balance Stage II VRS, with a P/V valve, with no UST add-on APCD; 

# Balance Stage II VRS, without a P/V valve, with no UST add-on APCD; 

# Vacuum assist Stage II VRS with and without an UST add-on APCD; 

# Vacuum assist Stage II VRS with and without an P/V valve; and 

# No Stage II VRS, with a P/V valve, and no UST add-on APCD (i.e., Stage I 

scenario). 

We did not receive data for a scenario with: 

# No Stage II VRS and no P/V valve; or 

# For no Stage II VRS, with a P/V valve, and with an UST add-on APCD. 

The data received are summarized below, including the testing scenarios, the test data, and 

related conclusions. Some data consisted primarily of parameter operating data and some data 

included emissions testing data as well. Each set of data provided information on one or more of 

the various emissions points from Stage II operations. Additional information is provided in 

Appendix A for each data set. 

1. California GDF Testing, Site 1 

The test was conducted to conclude whether an UST vent add-on APCD (i.e., a 

processor) would be necessary on a balance Stage II system to be compliant with the EVR UST 

pressure requirements (CP-201). The operating conditions of the GDF were monitored over a 

36-day test period during February and March in California, and fuels with different RVP were 

in use over the time period. The February winter fuel had a RVP of 13 psi and the March fuel 

had a RVP of 9 psi. No emissions measurement testing was conducted. The GDF shuts down 

every night for 6 hours. The gasoline throughput was 41 percent to ORVR-equipped vehicles, 

and the percentage of ORVR-equipped vehicles was 42 percent. 

Stage II balance VRS, with P/V valve, no UST vent add-on APCD. 

The system was at negative pressure for the majority of the test period and remains at 

negative pressure for long periods. The system passed weekly pressure decay tests, indicating 

the system was vapor tight. There are few to no periods at 0 in. w.c. (significant time at 0 in. 

w.c. would indicate leaks). Some positive pressure periods were seen during the testing but the 

frequency, magnitude, and duration were low. During the 36-day testing period, the CARB daily 

average pressure limit and the daily hourly maximum pressure were exceeded on a few days; 

however, the 30-day rolling average pressure met the CARB limits. The data are summarized in 

Table 16. The test demonstrates that the balance system meets the pressure profile requirements 
DRAFT 02-07-06

82

of CARB’s EVR CP-201, without the use of an UST add-on APCD (i.e., processor). In addition 

to meeting the CARB EVR pressure requirements, the UST pressure never exceeded 3 in. w.c. 

during the testing period, so the UST vent never opened. The V/L ratios for each fueling point 

over the 36-day period ranged from 0.71 to 1.0. 

Additional analysis was conducted to compare the UST pressures for the two RVP. The 

analysis was conducted on a subset of data, specifically for those shut down hours when no 

fueling is being conducted at the GDF. For the shutdown periods only, the 30-day rolling daily 

average was 0.35 in. w.c. for RVP of 13 psi and was 0.055 in. w.c. for RVP of 9 psi. The 30-day 

rolling average hourly maximum pressure was 2.4 in. w.c. for RVP of 13 psi and was 0.51 in. 

w.c. for RVP of 9 psi. 

Table 16. Pressure Data for Balance Stage II VRS Without an UST Add-on APCD 

Based on RVP 

Parameter 

Test period over 

February 1 through 

March 21, 2005 

Exceeded, 

days CARB limit High RVP 

(13 psi) 

Low RVP 

(9 psi) 

All Data a

CARB daily average 

P, in. w.c. 

+0.04 3 +0.25 in. w.c. NA NA 

30-day rolling 

average hourly 

maximum P, in. w.c. 

+0.32 2 +1.5 in. w.c. NA NA 

Average V/L Ranged from 0.71 to 1.0 

Calculated UST 

emissions from 

positive P periods 

7 lb HC during testing period; extrapolated annually to 48 lb/yr. 

Subset of data 

For GDF shutdown 

periods only, daily 

average P, in. w.c. 

NA NA NA +0.35 +0.055 

For GDF shutdown 

periods only, 30-day 

rolling average hourly 

maximum P 

NA NA NA +2.4 +0.51 

a Minus data from 13 days (February 16-28) prior to failed leak decay test. 

2. California GDF Testing, Site 2 

This test was conducted to determine whether the ORVR-compatible vacuum assist Stage 

II VRS and an UST add-on APCD are EVR compliant. The UST add-on APCD is an 

expandable bladder that accepts vapor from the UST during positive pressure periods. The 

operating conditions of the GDF were monitored in January and August 2004. No emissions 

testing was conducted. The GDF shuts down each night. The percentage of ORVR vehicles is 

not known, although it should not matter for an ORVR-compatible system. The daily average 

V/L ratio at the two pumps for the January time period ranged from 0.95 to 1.1 over the test 

period. A summary of the operating data and possible emissions implications is shown in 

Table 17. 
DRAFT 02-07-06

83

ORVR-compatible vacuum assist Stage II VRS, with P/V valve, without UST add-on APCD. 

Without the add-on APCD (August 11-17 data), the UST pressures ranged from 

approximately -9 in. w.c. to +3 in. w.c. During operating hours when the GDF was dispensing 

fuel from the UST, the significant negative UST pressures were maintained. During nighttime 

hours when the GDF was closed and not operating, there was consistent pressure increase, 

indicating vapor growth. The pressures during off-hours were often above 0 in. w.c., indicating 

pressurization of the tank and possible fugitive emissions. The pressures rose to +3 in. w.c. on 

some nights, indicating P/V valve venting and UST vent emissions and UST fugitive emissions 

as well. 

ORVR-compatible vacuum assist Stage II VRS, with P/V valve, with UST add-on APCD, 

and with a simulated fugitive leak. 

With the add-on APCD and a simulated fugitive leak, pressures ranged from -8 in. w.c. to 

approximately 0 in. w.c. There were a few momentary spikes in pressure (as high as +4.5 in. 

w.c.) with return to 0 in. w.c. During overnight hours, there was consistent pressure increase, 

indicating vapor growth. There are minimal episodes above 0 in. w.c. because the UST is vented 

to the flexible bladder at +0.15 in. w.c. (If the Clean Air Separator was not in place, significant 

positive pressures could not be maintained due to the leak that was simulated during this testing 

scenario.) During operating hours, the UST pressures decreased to negative pressures, however, 

with the simulated leak, not as much vacuum was pulled on the UST (i.e., the pressures did not 

appear to be as negative as shown in the “tight” UST data above). 

ORVR-compatible vacuum assist Stage II VRS, with P/V valve, and with UST add-on 

APCD. 

With the UST add-on APCD, the pressure ranged from approximately -9 in. w.c. to just 

above 0 in. w.c. During operating hours when the GDF was dispensing fuel from the UST, the 

UST pressures decrease and significant negative pressures are maintained. During nighttime 

hours when the GDF would be closed and not operating, there was consistent pressure increase, 

indicating vapor growth. However, there were minimal episodes above 0 in. w.c. because the 

UST vents to the flexible bladder at +0.15 in. w.c. 

Table 17. Pressure Data for ORVR-Compatible Vacuum Assist Stage II VRS 

Parameter Without add-on APCD 

With add-on APCD and a 

simulated leak With add-on APCD 

Range -9 to +3 in. w.c. -8 to 0 in. w.c. -9 to 0 in. w.c. 

During operating/ 

fueling hours 

Significant negative P Negative P Significant negative P 

Overnight Positive P overnight, 

sometimes > +3 in. w.c. 

No positive P because vented to 

APCD at +0.15 in. w.c. 

(If the APCD were not in place, 

significant positive P would not 

occur due to the fugitive leak; 

emissions would occur from 

fugitive leaks rather than at the 

UST vent.) 

No positive P because 

vented to APCD at 

+0.15 in. w.c. 
DRAFT 02-07-06

84

Parameter Without add-on APCD 

With add-on APCD and a 

simulated leak With add-on APCD 

UST emissions Significant fugitives, 

Significant vent emissions 

No fugitives, 

No vent emissions 

(If the APCD were not in place, 

significant fugitives would occur, 

however, no vent emissions would 

be likely.) 

No fugitives, 

No vent emissions 

3. California GDF Testing, Site 3 

This testing was conducted on a GDF in California with a balance Stage II VRS. The 

operating conditions of the GDF were monitored during a 7-day period in December. A total of 

486 vehicle fuelings occurred and a total of 2,816 gal were dispensed during the test period. The 

vehicles fueled during the test period were 100 percent ORVR, and the GDF closes for 8 hours 

each day. The UST pressures ranged from approximately -2.6 in. w.c. to +0.15 in. w.c. over the 

7-day period. The UST pressures seemed consistent with typical UST pressures for refueling, 

with higher pressures during nighttime hours when the GDF was closed (i.e., not dispensing fuel) 

and with negative pressures during operating hours (dispensing fuel). The UST pressures were 

less than or equal to 0 in. w.c. for 95 percent of the operating period, and were greater than 0 in. 

w.c. for 5 percent of the operating time. 

The pressure data indicate that the balance Stage II VRS used to fuel ORVR vehicles is 

not likely to generate excess emissions from the UST due to ORVR refuelings (from 

incompatibility). Because the UST pressures are negative for the majority of the time, fugitive 

emissions and UST vent emissions may be minimized. 

4. Florida GDF Testing, Site 1 

The Florida Department of Environmental Protection (DEP) and we observed testing at a 

GDF with a vacuum assist Stage II VRS that had an installed add-on APCD on the UST vent. 

The UST add-on APCD is a membrane system that accepts gasoline vapors during periods of 

positive UST pressure and recovers and returns the gasoline vapors to the UST. These data are 

for Florida in February, UST temperature of 74°F, ambient T of 71°F, RVP of fuel of 11.1 psia, 

V/L ratio of 0.97, and a fueling rate of approximately 8 gal/min; the percentage of ORVR 

vehicles fueled is not known. The UST vent emissions testing was conducted for an 

approximately 24-hr period for each testing scenario including both daytime operating hours 

(i.e., refueling) and during nighttime hours when no refueling operations occurred (i.e., the GDF 

was closed). The emissions data for all scenarios are shown in Table 18. 

Stage II VA VRS, no P/V valve, no UST add-on APCD. 

The emissions rate from the UST vent is 3.48 lb/1,000 gal and 2.78 lb/hr. 

Stage II VA VRS, with a P/V valve, no UST add-on APCD. 

The emissions rate from the UST vent is 1.20 lb/1,000 gal and 0.95 lb/hr. UST pressures 

during this testing were at +3 in. w.c., so fugitive emissions were likely occurring. The UST 

system passed the leak decay test; a portable HC analyzer, however, showed that drain valve 
DRAFT 02-07-06

85

bucket leaks became prominent at a pressure of +2.7 in. w.c. These emissions data likely 

represent low values in that fugitive leaks were occurring with the P/V valve in place. An 

emissions reduction of 59.8 percent from uncontrolled UST vent levels could be calculated, 

however, addition of the fugitive emissions (not quantified for the testing) that are occurring to 

this vent emissions value would likely show little to no decrease in emissions rate over the 

uncontrolled levels shown above (no P/V valve, no UST add-on APCD). 

Stage II VA VRS, with a P/V valve, with UST add-on APCD. 

The emissions rate from the UST vent is 0.014 lb/1,000 gal and 0.0113 lb/hr. The UST 

vents to the add-on APCD when the UST pressure reaches +0.5 in. w.c.; at these pressures, there 

should be little to no fugitive emissions occurring. These data represent an emissions reduction 

of 99.3 percent from uncontrolled UST vent rates. 

Table 18. Stage II VA VRS, with and without P/V Valve, with and without add-on APCD 

Source

Uncontrolled System, a

lbs/1,000 gal

Controlled System, b

lbs/1,000 gal

Controlled System, c

lbs/1,000 gal

UST vent emissions 3.48 1.20 0.014 

a

 Uncontrolled scenario means: with Stage II VA VRS, no P/V valve, no UST add-on APCD (ORVR 

unknown). 

b

 Controlled scenario means: with Stage II VA VRS, with P/V valve, no UST add-on APCD (ORVR unknown). 

This emissions data point does not include fugitive emissions that are occurring due to leaks in the UST 

system. c

 Controlled scenario means: with Stage II VA VRS, with P/V valve, with UST add-on APCD (ORVR 

unknown). 

5. Missouri GDF Testing, Site 1 

The emissions levels from the vehicle refueling fillpipe/nozzle interface, the spillage 

emissions, and the UST vent breathing and fugitives are shown in Table 19. Uncontrolled 

emissions levels were determined from AP-42 emissions factors. These data are for ambient T 

of 75°F and RVP of 11.3 psi. The emissions were determined for two types of nozzles. The 

emissions testing was conducted in October in Missouri and the bench testing was conducted 

from June through March. (The fueling rates in gal/min are not available.) During the vehicle 

refueling testing, 77 vehicles were refueled at pump 9 and 76 vehicles were refueled at pump 10. 

Vehicle matrix data on the model year vehicle and the make are available. The number of 

ORVR vehicles is not known. 
DRAFT 02-07-06

86

Table 19. Stage II Balance VRS, with P/V valve, no UST vent add-on APCD 

Efficiency Relative to 

Uncontrolled System

Source

Uncontrolled 

System 

(without VRS), 

lbs/1,000 gal

Controlled 

Pump 9 

Husky 5010 

(V Short), 

lbs/1,000 gal

Controlled 

Pump 10 

Husky 5210 

(V Long), 

lbs/1,000 gal

Pump 9 

Husky 5010 

(V Short)

Pump 10 

Husky 5210 

(V Long)

Vehicle Fueling 14.6 

[AP-42 EF 

equation] 

0.64 a

[emissions 

measurement] 

0.63 a

[emissions 

measurement] 

95.6% 95.7% 

Spillage/PseudoSpillage 0.46 0.083 

[measured] 

0.10 

[measured] 

82.0% 78.3% 

Breathing (Pressure 

Related Fugitives 

from components 

such as P/V valves 

and nozzles) 

1.00 

[AP-42 EF] 

0.16 

[calculated] 

0.16 

[calculated] 

84.0% 84.0% 

a

 A portion of this value was due to evaporation of liquid droplets on the nozzle after completion of each fueling 

event and really belongs in the spillage/pseudospillage category. 

6. Missouri GDF Testing, Site 2 

The emissions levels from the vehicle/nozzle interface, the spillage emissions, and the 

UST vent breathing and fugitive emissions are shown in Table 20. The uncontrolled emissions 

levels were determined from AP-42 emissions factors. These data are for ambient T of 75°F and 

RVP of 12.76 psi. The emissions testing was conducted in October and the bench testing was 

conducted from May through December. During the vehicle refueling testing, a total of 205 

vehicles were refueled. Approximately 5 of these were ORVR vehicles (which reflected the 

actual ORVR percentage of the vehicle fleet at that time, 2.4 percent). The fueling rate in 

gal/min is not available. Vehicle matrix data on the model year vehicle and the make are 

available. 

Table 20. Stage II Balance VRS, with P/V valve, no UST vent add-on APCD 

Source

Uncontrolled System 

(without VRS), 

Lbs/1,000 gal

Balance VRS, 

lbs/1,000 gal

Efficiency Relative 

to Uncontrolled 

System

Vehicle Fueling 14.6 

[AP-42 EF equation] 

0.79 

[emissions 

measurement] 

95.2% 

Spillage/Pseudo-Spillage 0.46 0.02 

[measured] 

97.8% 

Breathing (Pressure Related 

Fugitives from components such 

as P/V valves and nozzles) 

1.00 

[AP-42 EF] 

0.06 

[calculated] 

94.0% 
DRAFT 02-07-06

87

7. Missouri Automobile Manufacturer GDF Testing, Site 3 

The emissions levels from the vehicle fueling fillpipe/nozzle interface, the spillage 

emissions, and the UST vent breathing and fugitives are shown in Table 21. Emissions testing 

was conducted to measure the uncontrolled emissions levels for vehicle fueling; the testing was 

conducted in March with ambient T of 72oF and filling rate of 6 to 9 gal/min (assumed RVP of 

11.99 psi). The uncontrolled spillage and breathing losses were determined from AP-42 

emissions factors and CARB EFs. The controlled emissions levels for vehicle fueling were 

determined by emissions testing in March with chilled gasoline at 50oF and a filling rate of 6 

gal/min (assumed RVP of 11.99 psi). The testing for continuous pressure and temperature was 

conducted from September through December, and the bench testing was conducted in February, 

September, and December. All of the vehicles were ORVR, with a single canister design. 

(Some data are also available for dual canister ORVR at this site but are not shown here.) 

In addition to the emissions testing, T and P operating data for the UST are available for a 

103-day period and a summary of the data is shown in Table 22. Typical weekday pressures 

show increasing pressures, indicating vapor growth, for overnight periods and negative pressures 

during daytime fueling operations. Typical weekend day pressures showed positive pressures for 

day and night periods. The UST pressures were greater than 0 in. w.c. for 29.6 percent of the test 

period (pressure-related fugitives are likely occurring) and were greater than +3.0 in. w.c. for 4.2 

percent of the testing period (UST vent emissions are likely occurring). A leak was fixed on day 

72 of the test. Another analysis of the pressure data was conducted for the time period before 

and after the leak. The tank maintains negative pressures for longer periods after the leak is 

fixed (48 percent of the time) than before (19 percent). In addition to maintaining negative 

pressures, the UST will also “better” maintain positive pressures after the leak is fixed; UST vent 

emissions are more likely to occur in a tight system, in place of UST fugitive emissions that 

occur in leaking systems. Because the UST at automobile manufacturing facilities have longer 

vapor growth periods, the UST emissions from these operations may be higher than would 

typically be seen at a traditional GDF. 

Table 21. No Stage II VRS, with a P/V valve, no UST vent add-on APCD 

Source

Uncontrolled System a

[in MY2001/2002 mockup 

tanks] 

lbs/1,000 gal

Controlled b MY2003 - 

mockup, 

lbs/1,000 gal

Efficiency Relative to 

Uncontrolled System

Vehicle Fueling 17.6 

[emissions measurement] 

0.0779 

[emissions measurement] 

99.6% 

Spillage/Pseudo-Spillage 0.75 

[CARB EF] 

0.48 

[measured] 

36.0% 

Breathing (Pressure 

Related Fugitives) 

 - UST emissions 

 - fugitives 

1.0 

[modified AP-42 equation] 

0.24 

[calculated based on P, T, 

time] 

76.0% 

a

 Uncontrolled scenario means: No chilling, no ORVR, no Stage II VRS, w/ P/V valve [some vapor return from a s

fueling area balance nozzle, but this has a small impact because small gasoline throughput]. 

b

 Controlled scenario means: with Chilling, with ORVR single, and No Stage II VRS. 
DRAFT 02-07-06

88

Table 22. Analysis of Frequency Plots for UST Pressure for All Data and Before/After 

Fixing the Leak 

Pressure ranges, All data Before leak is fixed After leak is fixed

in. w.c. minutes % minutes % minutes %

< -8.0 40,809 27.9% 19,680 19.2% 21,129 48.3% 

-8.0 < P < 0.0 62,137 42.5% 50,166 48.9% 11,971 27.4% 

<0.0 102,946 70.4% 69,846 68.1% 33,100 75.7% 

>0.0 43,265 29.6% 32,651 31.9% 10,614 24.3% 

>3.5 6,249 4.27% 4,184 4.08% 2,065 4.72% 

8. Missouri Automobile Manufacturing GDF, Site 4 

The emissions levels from the vehicle fueling fillpipe/nozzle interface, the spillage 

emissions, and the UST vent breathing and fugitives are shown in Table 23. Emissions testing 

was conducted to measure the uncontrolled emissions levels for vehicle fueling; the testing was 

conducted in March with ambient T of 72oF and filling rate of 8 gal/min (assumed RVP of 11.99 

psi). The uncontrolled spillage and breathing losses were determined from AP-42 emissions 

factors and CARB EFs. The controlled emissions levels for vehicle fueling were determined by 

emissions testing in March with chilled gasoline at 43oF and with a filling rate of 8 gal/min 

(assumed RVP of 11.99 psi). The testing for continuous pressure and temperature was 

conducted in October and November, and the bench testing was conducted in August, 

September, and December. All of the (controlled) assembly line vehicles and the uncontrolled 

mockup tanks were ORVR (dual), and the controlled mockups for the MY2004 were ORVR 

(single). 

Table 23. No Stage II VRS, with a P/V valve, no UST vent add-on APCD 

Source

Uncontrolled 

System a

MY2003 

mockup tanks 

lbs/1,000 gal

Controlled 

MY2003 b

assembly line, 

dual canister, 

lbs/1,000 gal

Efficiency 

Relative to 

Uncontrolled 

System 

Controlled 

MY2004 b

mockup 

tanks, single 

canister, 

lbs/1,000 gal

Efficiency 

Relative to 

Uncontrolled 

System

Vehicle Fueling 13.5 

[emissions 

measurement] 

0.0118 

[emissions 

measurement] 

99.9% 0.0033 

[emissions 

measurement] 

greater than 

99.9% 

Spillage/PseudoSpillage 0.75 

[CARB EF] 

0.063 

[measured] 

91.6% same same 

Breathing (Pressure 

Related Fugitives) 

 - UST emissions 

 - fugitives 

2.09 

[modified AP-42 

EF] 

0.267 

[calculation 

based on P, T, 

time] 

87.2% same Same 

a

 Uncontrolled scenario means: No chilling of gasoline, no ORVR, no Stage II VRS, and with P/V valve. 

b

 Controlled scenario means: With chilling of gasoline, with ORVR, No Stage II VRS, with P/V valve, and with 

purge puff nozzle. 
DRAFT 02-07-06

89

UST Operating Data for No Stage II VRS and with P/V valve. 

Some typical UST operating pressure data are shown in Table 24. The pressure data 

show a pattern of high vacuum during production operations on weekdays (i.e., fueling) and 

higher pressures close to or at the cracking pressure of the P/V valves during off times (overnight 

and weekends). Because the UST at automobile manufacturing facilities have longer vapor 

growth period, the UST emissions from these operations may be higher than would typically be 

seen at a traditional GDF. 

Table 24. Summary of Weekday and Weekend UST Vent Pressures (No Stage II VRS, 

with P/V valve) 

Friday, 

11/08

Saturday, 

11/09

Sunday, 

11/10

Monday, 

11/11

Tuesday, 

11/12

Wednesday, 

11/13

Thursday, 

Pressure, 11/14

psi N S N S N S N S N S N S N S 

Minimum -9.29 -10.62 -9.12 -10.48 1.26 1.19 -9.16 -10.72 -9.25 -10.65 -9.23 -10.58 NA NA 

Maximum 3.37 3.30 3.40 3.35 3.32 3.22 3.36 3.34 3.39 3.38 3.63 3.58 3.59 3.51 

Average -6.10 -6.87 1.80 1.62 2.58 2.49 -5.27 -5.90 -6.59 -7.33 -5.81 -6.43 -15.44 -11.17 

Friday, 

 11/15

Saturday, 

11/16

Sunday, 

11/17

Monday, 

Pressure, 11/18

psi N S N S N S N S 

Minimum -9.06 -10.47 1.60 1.52 2.27 2.26 -9.29 -10.77 

Maximum 3.38 3.35 3.12 3.06 3.04 3.03 3.06 3.03 

Average 1.58 1.44 2.64 2.59 2.79 2.76 -5.08 -5.77 

Note: Data are provided for pressure gauges at both the north and south ends of the UST. 

9. New Hampshire GDF Data 

The NH DES monitored approximately 300 GDF in New Hampshire to determine the 

extent of groundwater pollution with MTBE. The GDF that were monitored included a number 

of different control types, including balance and vacuum assist Stage II VRS, and some GDF 

without Stage II VRS controls. The groundwater monitoring data show that a number of the 

GDF have detectable levels of MTBE and a number have exceeded the groundwater limit. With 

the MTBE limit for groundwater at 13 ppb, approximately 88 GDF exceeded the limit. Of these 

88 GDF, 51 are confirmed to be vacuum assist Stage II VRS that are not ORVR compatible. The 

last MTBE concentration readings for those GDF that exceeded the limit ranged from 18 to 

1,110,000 ppb. 

10. Multi-State GDF Data 

Testing for multiple GDF with Stage II VRS controls was conducted in 17 States over a 

15-month period. Testing included pressure decay tests (static pressure performance test), 

dynamic backpressure tests, and A/L ratio testing. A total of 7,514 pressure decay tests were 

conducted over this time period in the 17 States. Of these pressure decay tests, approximately 19 

percent failed, and the failure rate from State to State ranged from 0 percent (only 2 GDF were 

tested) to 29 percent. These failures occurred despite retesting following maintenance attempts 

by the test technician to repair tank fittings, dispenser fittings, and hanging hardware while onsite 

when a GDF failed an initial try. 
DRAFT 02-07-06

90

A number of dynamic backpressure tests were conducted, with 3,974 tests on the gasoline 

(wet) side and 3,916 on the vapor (dry) side. These tests check for any blockage in the gasoline 

or vapor piping or hoses. Overall, approximately 6.5 percent of the wet backpressure tests were 

failures (ranging from 0 to 33 percent from State to State) and 3.4 percent of the dry 

backpressure tests were failures (ranges from 0 to 25 percent). 

There were 4,313 A/L ratio tests summarized in the data. Approximately 27 percent of 

the tests were failures; these tests are considered to be failures if even one fueling point at the 

GDF fails and cannot be repaired by the technician or if a fueling point is out of order when the 

test is conducted. All fueling points must be working properly to pass the test. 

A summary of the testing and the failure rates by States is provided in Table 25. 

Information on the frequency requirements for specific tests is also provided. There is much 

variability in the failure rate from State to State and also from test type within a single State. 
91 

Table 25. Stage II VRS Testing and Failure Rates by State 

Pressure decay tests Backpressure tests Backpressure tests A/L ratio tests 

State 

PD Test 

Pressure, 

in. w.c. Tests Fails a Fail, % WetB Tests WetB Fails b Fail ,% DryB Tests DryB Fails b Fail ,% Tests Fails c Fail ,% T

CT 10 180 34 19 143 5 4 143 3 2 54 22 41 Every 3 years 

on 7/26/04, A/date) 

DC 2 60 6 10 46 1 2 46 – – 70 30 43 Annual (Vac-aDE 10 115 14 12 50 4 8 49 – – 106 33 31 Annual all testFL 2 92 8 9 60 2 3 60 2 3 51 2 4 PD & A/L Ann

in Miami-DadBroward 

MA 10 1,268 115 9 678 18 3 680 9 1 1,029 248 24 PD & A/L ann

blockage every 

MD 2 723 142 20 71 8 11 71 5 7 621 211 34 PD & A/L ann

blockage annuevery 5 years f

ME 10 28 5 18 3 1 33 3 – – 24 7 29 PD & A/L Ann

every 5 years, years for balan

NC 10 2 – – 2 – – 2 – – – – – PD & BlockagNH 10 67 8 12 56 1 2 56 1 2 44 15 34 Every 3 years NJ 2 2,496 672 27 1,533 113 7 1,532 52 3 606 153 25 PD & A/L ann

blockage every changed from year) 

NY 10 914 223 24 731 64 9 732 35 5 279 93 33 PD & B Every 

requirement) 

OH 2 131 8 6 64 – – 4 1 25 157 27 17 PD & A/L ann

blockage every 

PA 2 1,039 128 12 378 29 8 379 20 5 1,019 251 25 PD & A/L Ann

every 5 years, years for balan

RI 10 155 16 10 76 5 7 76 1 1 157 51 33 PD & A/L ann

blockage every 

SC 2 – – – – – – – – – – – No requiremenVA 2 231 67 29 82 8 10 82 6 7 95 33 35 PD & Blockag

systems (A/L a
92 

Pressure decay tests Backpressure tests Backpressure tests A/L ratio tests 

State 

PD Test 

Pressure, 

in. w.c. Tests Fails a Fail, % WetB Tests WetB Fails b Fail ,% DryB Tests DryB Fails b Fail ,% Tests Fails c Fail ,% T

VT 10 11 – – 1 – – 1 – – 1 – – PD & A/L eve

wet/dry blockabalance only 

Total 7,514 1,446 19.2% 3,974 259 6.52% 3,916 135 3.45% 4,313 1,176 27.3% 

 Avg Avg Avg Avg 

a Pressure decay failures are considered failures after all attempts have been made by the technician to repair. b Blockage failures are underground blockage failures. c A/L failures are considered failures if even one fueling point at the site fails and cannot be repaired.The only time A/L is considered a pass is when 

working properly at the time of the test. 
DRAFT 02-07-06

93 

11. Vermont GDF Data 

Testing was conducted at 32 GDF to determine how well in-use GDF systems maintain 

compliance with performance standards and the level of effort required to bring GDF back into 

compliance. Nineteen percent of GDF were balance and 81 percent were various types of VA 

VRS. No recent maintenance had been conducted at these facilities. Testing included (1) 

pressure decay tests, (2) A/L ratio test for VA VRS, and (3) vacuum line integrity test for GDF 

with a central vacuum pump. Testing was conducted on an “as is” basis, i.e., without any 

maintenance being conducted prior to testing. The technicians also tracked the amount of effort 

to bring each GDF into compliance. The conclusions from these data are that a significant 

number of GDF will fail pressure decay testing without ongoing maintenance. Another 

conclusion is that the majority of GDF do meet the A/L ratio requirements. 

Pressure decay tests. 

A total of 90 USTs, 128 gasoline dispensers, and 360 gasoline nozzles were included in 

the testing. Fill caps and Stage I poppet valves were the equipment components involved in 

failure of the pressure decay test; the balance nozzles contributed to the failure at all of the 

balance VRS GDF. Twelve percent of the fill caps, 27 percent of Stage I poppet valves, and 23 

percent of balance nozzles were found to be leaking. Data on the pressure decay tests is 

provided in Tables 26 through 29. 

Table 26. Initial Pressure Decay Test Results 

Subset of 

GDF 

No. of GDF 

(percentage) 

No. Pass 

(percentage) 

No. Fail 

(percentage) 

All stations 31 (100%) 10 (32%) 21 (68%) 

VA 25 (81%) 10 (40%) 15 (60%) 

Balance 6 (19%) 0 (0%) 6 (100%) 

Table 27. Margin by Which Pressure Decay Test Failed 

Pass/Fail description 

Percent of 

total stations 

Pass – Within Allowed Leak Rate 32 

Fail – Up to 10% Above Allowed Leak Rate 26 

Fail – Between 10% and 50% Above Allowed Leak Rate 13 

Fail – Greater than 50% Above Allowed Leak Rate 29 
DRAFT 02-07-06

94 

Table 28. Equipment Problems that Contributed to Pressure Decay Test Failure 

Part 

Percent of Failing Stations Where 

Component Was a Factor a

Fill Cap 41 

Stage I Poppet Valves 41 

Fill Adaptor 32 

Spill Bucket Drain Valve 27 

Nozzle b 27 

Breakaway 14 

In-Tank Monitor 5 

Submersible Pump 5 

a

 At most GDF, more than one component contributed to failure, therefore, 

percentages do not add to 100 percent. 

b

 Nozzles were a contributing factor only at balance stations. 

Table 29. Parts Found Leaking During Pressure Decay Tests 

Part 

Number 

Leaking 

% Leaking, Out of Total 

Number Tested 

Fill Cap 11 12 

Stage I Poppet Valve 15 27 

Fill Adaptor 9 10 

Spill Bucket Drain Valve 12 not determined 

Balance System Nozzle 13 23 

Breakaway 3 <1 

In-Tank Monitor 3 not determined 

Submersible Pump 1 1 

Vacuum Line Integrity Test. 

Vacuum line integrity testing was performed at two GDF with VA VRS that had a central 

vacuum source. Both GDF passed this test on the initial attempt. 

A/L Ratios. 

A/L ratio tests were performed at 26 VA VRS GDF and involved testing of 298 nozzles. 

The majority of nozzles passed the A/L ratio testing. Most nozzles that failed did so with a small 

margin. Information on the A/L ratio testing is provided in Table 30. 
DRAFT 02-07-06

95 

Table 30. A/L Ratio Testing Results 

Percent of Nozzles 

Status WayneVac 

Gilbarco 

Vapor Vac Healy 

Franklin 

Intellivac 

Within Allowable Range 85 94 92 100 

Fail– Within 10% of Allowable Range 11 4 4 0 

Fail– Between 10% and 50% of Allowable Range 2 2 4 0 

Fail– Greater than 50% of Allowable Range 2 0 0 0 

Number of GDF Tested: WayneVac = 15 (186 nozzles); Gilbarco VaporVac = 8 (48 nozzles); 

Healy = 2 (56 nozzles); Franklin = 1 (8 nozzles).

Required Effort to Attain Compliance. 

Following test failures, the testing technician conducted repairs, adjusted equipment, and 

replaced broken or worn components. For more than 50 percent of the components, minor 

maintenance such as tightening was sufficient to stop leaks. At 6 of 21 GDF, tightening of parts 

or other adjustments was sufficient to pass the pressure decay test; at 15 of 21 GDF, replacement 

of one or more parts was required. 

For the A/L ratio failures, adjustment of the vacuum motor or replacement of nozzles 

resolved most problems. 

Overall, replacement parts at 19 GDF cost $6,315 ($332/GDF). 

12. EPA’s Initial In-Use Evaporative Testing of ORVR Vehicles 

Two-day evaporative testing was conducted on a total of 32 ORVR vehicles of various 

ages. The odometer readings ranged from 6,800 to 190,000 miles, with an average of 45,000 

miles per vehicle. Of the 32 vehicles testing, 28 passed the evaporative testing, indicating an 88 

percent pass rate. While these evaporative system tests do not provide information specifically 

on the control efficiency of ORVR canisters, these tests do provide data indicating that most 

ORVR systems are operating correctly. 

13. EPA’s IUVP 

The latest EPA data from the IUVP includes testing on a total of 151 ORVR-equipped 

vehicles, using FTPs for the outlet of the ORVR canister. Overall, 9.3 percent of the ORVRequipped vehicles (14 out of 151) had canister emissions greater than the 0.2 g/gal limit. An 

analysis of the data with respect to high mileage versus low mileage vehicles was also 

conducted. Of the high-mileage vehicles, 13 percent (6 out of 47) had emissions greater than the 

0.2 g/gal limit. Of the low-mileage vehicles, 7.7 percent (8 out of 104) had emissions greater 

than the 0.2 g/gal limit. These results are presented in Table 31. 
DRAFT 02-07-06

96 

Table 31. EPA IUVP Test Results 

Overall Low Mileage High Mileage 

Test Result Number Percentage Number Percentage Number Percentage 

< 0.2 g/gal 137 91% 96 92% 41 87% 

> 0.2 g/gal 14 9.3% 8 7.7% 6 13% 

Total 151 100% 104 100% 47 100 

B. Other Data Found within Literature

1. WSPA – UST vent emissions 

This study measured VOC emissions from the UST vent and determined the effect of 

tank capacity and P/V valves on emissions levels. Conclusions drawn (by the authors of the 

study) from this testing indicated that the UST vent emissions are not directly correlated to the 

UST capacity, the product throughput, or the ambient T and P. It was also concluded from these 

emissions data that working losses compared to breathing losses are a small part of total UST 

vent emissions. 

Stage II balance VRS, without a P/V valve, no UST vent add-on APCD. 

The emissions level from the UST vent is 0.083 lb/1,000 gal. The ambient T, RVP of the 

fuel, and the fueling rate are not known. There were no ORVR vehicles refueled during the 

testing (conducted prior to ORVR implementation). 

Stage II balance VRS, with P/V valve, no UST vent add-on APCD. 

The emissions level from the UST vent is 0.024 lb/1,000 gal. (Same scenario discussed 

in the previous paragraph.) 

2. ORS Pilot Study 

This pilot study was conducted to evaluate optical remote sensing (ORS) technology for 

determining emissions factors. The study was conducted over a 3-day period at a retail gasoline 

outlet (RGO) with no Stage II VRS and without P/V valves. Both open-path Fourier transform 

infrared (OP-FTIR) and open-path ultraviolet (OP-UV) systems were used to determine gasoline 

vapors, benzene, and toluene and these values were compared to the AP-42 emissions factors. A 

vehicle refueling emissions factor and a total emissions factor (including fugitive and vehicle 

refueling emissions from ground level and vent pipes from elevated releases) were measured and 

calculated and are shown in Table 32. 

The study showed that both OP-FTIR and OP-UV systems detected emissions from 

vehicle fueling, UST vents, and fugitive emissions. In comparing the emissions to the AP-42 

emissions factors, the OP-FTIR determined vehicle refueling emissions factors were higher. The 

study suggested that the results may be site-specific and conclusions may not be applicable to 

other RGO facilities. 
DRAFT 02-07-06

97 

Table 32. Optical Remote Sensing at an RGO with No Stage II VRS and No P/V Valve 

Source

Measured Emissions 

Factor

Emissions Factor Based 

on AP-42 Equation

Vehicle Fueling, no Stage II VRS, 

OP-FTIR (F1) 

0.16% + 0.05%, mass 

percent a

0.11% (using generic T and RVP) 

0.12% ± 0.02% (using UST T for dispensed fuel T 

and using ambient T for vehicle tank fuel) 

Vehicle Fueling, no Stage II VRS, 

OP-FTIR (F2) 

0.15% + 0.03%, mass 

percent a

0.11% (using generic T and RVP) 

0.12% ± 0.02% (using UST T for dispensed fuel T 

and using ambient T for vehicle tank fuel) 

Average Total Emissions Factor, 

OP-FTIR (F1) 

0.32% a – 

Average Total Emissions Factor, 

OP-FTIR (F2) 

0.35% a – 

a

 Compares average mass of vapors emitted (kg emitted ) to the average mass of gasoline dispensed (kg 

dispensed). 

C. Planned Testing

1. Florida GDF Testing, Site 2 

The Florida Department of Environmental Protection (Florida DEP) is planning testing at 

a station with no Stage II VRS. The Florida DEP contact indicates that this testing is to occur in 

the Fall of 2005. The station has installed ARID’s Permeator system in lieu of Stage II VRS and 

has requested a variance for 24 months or until Stage II VRS is no longer required, whichever is 

earlier. EPA may observe some of the testing and obtain additional data to address some of the 

Stage II VRS issues. 

2. Hertz Testing, Rental Car Facilities 

Hertz believes that because their vehicle fleet is almost entirely comprised of vehicles 

with ORVR equipment and because maintaining Stage II VRS is redundant, removal of Stage II 

VRS at their facilities would not result in an increase in VOC emissions. To demonstrate this, 

Hertz is considering testing of emissions from the fillpipe and UST vent using the CARB TP201.2 test protocol. During the testing, Hertz will also collect data on UST system leak tightness 

and/or tank pressure. Hertz is considering testing at a vacuum assist Stage II VRS station 

without an UST add-on APCD, at a vapor balance Stage II VRS station without an UST add-on 

APCD, and at a station with no Stage II VRS. Data from these tests would address some of the 

current data gaps. 

3. New Hampshire GDF Testing 

[Editorial note – the New Hampshire testing described in this section has been canceled 

due to scheduling and funding issues.] 

The NH DES, the UNH, GVR, and EPA plan to conduct testing at a GDF in New 

Hampshire beginning in January and continuing through April 2006. The GDF has a vacuum 

assist Stage II VRS in place and will have an ISD system installed at the site. There are 3 

gasoline UST and one diesel UST at the facility. Testing will be conducted for two scenarios. 
DRAFT 02-07-06

98 

The first (baseline) will be testing of the Stage II VRS currently in place, and the second scenario 

(follow-up) will involve conversion to an ORVR-compatible Stage II VRS by installing the 

Healy EVR Phase II system. The GDF site is subject to the NH DES Groundwater Management 

Permit (GMP) program to monitor petroleum discharges that are believed to have occurred at the 

site. The facility is required to monitor three times per year for a number of specific VOCs and 

static water elevations at eight on-site and two off-site monitoring wells. MTBE and TAME 

have been the major contaminants at the site. ORS systems will be used to measure emissions 

from vehicle refueling, UST vents, and fugitives. The objectives of the emissions testing 

include: 

# Obtaining OP-FTIR measurements for aliphatic compounds, such as methanol, 

ethanol, MTBE, and other HAP; 

# Obtaining UV-DOAS measurements for benzene, toluene, ethylene, and xylenes 

(BTEX) compounds; 

# Calculating emissions fluxes downwind from major hot spots; 

# Identifying major hot spots by generating surface concentration maps in the 

horizontal plane; and 

# Obtaining more sensitive measurements of aromatic HC across identified hot spots. 

4. Arizona GDF Testing 

In collaboration with the Salt River Pima Maricopa Indian Community, we conducted 

ORS testing at two GDF in Arizona in October 2005 to measure emissions from vehicle 

refueling, UST vents, and fugitives.. One GDF has no Stage II VRS and the other has a vacuum 

assist Stage II VRS. The objectives of these emissions tests are the same as those mentioned 

above for the New Hampshire testing. Results are being summarized. 

VII. NESCAUM Widespread Use Study 

As previously discussed in this paper, there are four possible definitions being considered 

for defining widespread use of ORVR. Definition (a) (percentage of ORVR-equipped vehicles) 

is based on vehicle registration data, projections of that data into the future, and the phase-in 

schedule for ORVR. Definition (b) (percentage of VMT by ORVR-equipped vehicles) is based 

on all of the data inputs for definition (a) plus the VMT data by class of vehicle. Definition (c) 

(VOC emissions with ORVR controls equal VOC emissions with Stage II VRS only) requires 

comparison of calculated vehicle refueling emissions based on two different refueling control 

measures. This definition requires the data inputs for definitions (a) and (b) along with data on 

ambient temperature, RVP, rule effectiveness, rule penetration, and the percentage of GDF with 

vacuum assist Stage II VRS (to determine incompatibility excess emissions). Definition (d) 

(gasoline dispensed to ORVR-equipped vehicles) requires data on the volume of gasoline sold in 

addition to the data inputs needed for definition (b). 

The EPA used data provided by NESCAUM from three states (Massachusetts, New 

Hampshire, and Vermont) to calculate widespread use for each potential definition. The 

algorithms are based on MOBILE6 data/equations. This section summarizes the calculation 

results for determining the widespread use date for each potential widespread use definition. 
DRAFT 02-07-06

99 

A. Methodology for Determining Widespread Use 

Algorithms used for calculating widespread use are based on MOBILE6 equations, with 

the addition of an IEE factor for ORVR-equipped vehicles refueling at GDF equipped with 

vacuum assist Stage II VRS.5949 An IEE factor of 0.86 lb/1,000 gal (based on CARB’s findings) 

was used for calculation purposes. The algorithms calculated VOC emissions for a summer day 

in a given calendar year (CY) for all gasoline vehicle types under the following control 

scenarios: 

1. Emissions from Stage II VRS only, without ORVR, 

2. Emissions from ORVR only, without Stage II VRS, 

3. Emissions from compatible Stage II VRS and ORVR, and 

4. Emissions from incompatible Stage II VRS and ORVR. 

Equations based on MOBILE6 were also used to calculate the percentage of VMT from 

ORVR-equipped vehicles in a given CY and to calculate the percentage of gasoline dispensed to 

ORVR-equipped vehicles in a given CY. 

MOBILE6 refueling emissions factors have two components. The first component is for 

vapor displacement and the second is for spillage. The uncontrolled vapor displacement 

emissions factor and spillage emissions factor for vehicle refueling are used in all calculation 

scenarios. The uncontrolled vapor displacement emissions factor is area-specific in the sense it 

accounts for ambient temperature and gasoline volatility or Reid Vapor Pressure (RVP), which 

are inputs to the MOBILE6 model. An uncontrolled spillage emissions factor of 0.31 grams per 

gallon is used in all calculations [MOBILE6 applies a 50 percent control level to spillage for 

ORVR]; this value is consistent with the value presented in AP-42 (Chapter 5.2 Transportation 

and Marketing of Petroleum Liquids). Algorithm equations are presented in Appendix B - 

NESCAUM Widespread Use Study Supporting Documentation, along with a description of each 

equation. Appendix B also contains the calculation spreadsheets. 

B. NESCAUM Provided Data 

NESCAUM provided EPA with data from three states to aid in analysis and comparison 

of the widespread use dates determined for each potential widespread use definition. 

NESCAUM was asked to supply the following data for each state: 

# Stage II VRS In-use Control Efficiency (CE); 

# Ambient Temperature Data (used to calculate refueling emissions); 

# In-use RVP of the gasoline used during the summer ozone season, and whether the 

gasoline was RFG; 

# Total gasoline usage, gallons/yr for the most recent available CYs and for those years 

that the states have projected data; 

 

59 API commissioned Tech Environmental to develop a spreadsheet to reproduce data from the MOBILE6 that 

includes IEE from ORVR-equipped vehicles and vacuum assist Stage II VRS. 
DRAFT 02-07-06

100 

# Percentage of GDFs equipped with balance Stage II VRS, and percentage of GDFs 

equipped with vacuum assist Stage II VRS, and percentage of GDFs equipped with 

balance Stage II VRS and Stage I (indicate the percentage of Stage I GDFs not 

equipped with P/V valves); 

# Percentage of GDFs equipped with Stage I, but not equipped with Stage II, and the 

percentage of Stage I GDFs not equipped with P/V valves; 

# Expected percentages of balance and vacuum assist for new VRS installations (i.e., x 

percent of new VRS installations will be balance systems; y percent of new VRS 

installations will be vacuum assist); 

# Vehicle distribution data by vehicle type and age; 

# Vehicle mileage accumulation data; 

# Vehicle miles traveled (VMT) data; 

# Diesel sales fraction data; 

# Vehicle fuel economy data; 

# Alternatively-Fueled Vehicle (AFV) penetration data; and 

# Anti-Tampering Program data. 

If the state was unable to provide area specific data, EPA used MOBILE6 default values, 

which are based on national averages. Table 33 summarizes the data collected from each state 

and indicates which MOBILE6 default values were used in the algorithms for determining 

widespread use. 

Table 33. Data Provided by NESCAUM 

Provided Data 

Or 

MOBILE6 Defaults Used 

Requested Data Massachusetts New Hampshire Vermont 

Stage II VRS CE 9 9 9

Ambient Temperature Data 9 9 9

In-use RVP of the gasoline used during the summer 

ozone season, and indicate if the gasoline is RFG 

9 9 9

Total gasoline usage, gallons/yr for the most recent 

available CYs and for those years that the states 

have projected data 

9 9 9

Percentage of GDFs equipped with balance Stage II 

VRS 

9 9 9

Percentage of GDFs equipped with vacuum assist 

Stage II VRS 

9 9 9

Percentage of GDFs not equipped with Stage II 

VRS, but equipped with Stage I. Also indicate the 

percentage of Stage I GDFs not equipped with P/V 

valves 

9 9 9
DRAFT 02-07-06

101 

Provided Data 

Or 

MOBILE6 Defaults Used 

Requested Data Massachusetts New Hampshire Vermont 

Percentage of GDFs equipped with balance Stage II 

VRS and Stage I. Also indicated the percentage of 

Stage I GDFs not equipped with P/V valves 

9 9 9

Vehicle distribution data by vehicle type and age 9 9 Defaults 

Vehicle mileage accumulation data Defaults Defaults Defaults 

Vehicle miles traveled (VMT) for the most recent 

calendar year and any years where projected data 

are available 

9 9 9

VMT fractional mix (represents the fraction of total 

highway VMT accumulated by each vehicle type) 

Defaults 9 Defaults 

Diesel sales fraction data 9 Defaults Defaults 

Vehicle fuel economy data Defaults Defaults Defaults 

Anti-Tampering Program data 9 9 9

9 Denotes that data provided by the State was used in the analysis. 

C. Results of Widespread Use Analysis 

A widespread use date for definitions (a), (b), (c), and (d) were determined for each state. 

A variation of definition (c) was also considered in the analysis of widespread use dates. API 

suggested that definition (c) needed to be modified to clearly identify the date at which there 

would be no emissions increase as a result of removing Stage II VRS.6050 Specifically, the 

modified definition (c), referred to as definition (c2), is when the total VOC emissions from 

ORVR-equipped vehicles are equal to or less than the total VOC emissions from Stage II VRS 

and ORVR, including IEE. The input values for key parameters (except vehicle mix) provided 

by the three states and used for the analysis are summarized in Table 34. 

Table 34. Values for Key Parameters 

Parameter MA NH VT 

Stage II VRS in-use Control Efficiency, % 84 68.6 62.4 

Minimum Ambient Temperature, °F 60.9 a 62 b 59.9 a

Maximum Ambient Temperature, °F 79.4 a 92 b 81.2 a

RVP, psi 6.8 (RFG) 6.8 (RFG) 8.5 

Percent of VRS that are Balance, % 41 20.4 10 

Percent of VRS that are Vacuum Assist, % 59 79.6 90 

a Average summer day. 

b

 Probably minimum, maximum (not average).

 

60 Memorandum from T. Tamura, STI, to P. Searles, API. March 3, 2005. Onboard refueling vapor recovery 

(ORVR) systems – proposed definitions of “widespread use.” 
DRAFT 02-07-06

102 

Table 35 summarizes the results of the analysis. Based on the assumptions for this 

analysis and applying the emissions-based calculations [definitions (c) and (c2)], widespread use 

occurs within the 7-yr window of 2008 to 2015. Using the definitions based on the percentage of 

VMT by ORVR-equipped vehicles and the percentage of fuel dispensed to ORVR-equipped 

vehicles [definitions (b) and (d)] and the criterion of 85 to 90 percent, widespread use occurs 

within the 5-year window of 2011 to 2016. 

Table 35. Summary of Algorithm Analysis 

Definition Description 

MA 

WSU Date 

NH 

WSU Date 

VT 

WSU Date 

85% of fleet with ORVR 2015 

(a) 90% of fleet with ORVR 2017 

95% of fleet with ORVR 2023 

85% of VMT from ORVR-equipped 

vehicles 

2011 2012 2013 

90% of VMT from ORVR-equipped 

vehicles 

2012 2013 2015 (b) 

95% of VMT from ORVR-equipped 

vehicles 

2015 2016 2019 

(c) Emissions from ORVR only are equal 

to emissions from Stage II only 

2010 2008 2008 

(c2) 

Emissions from ORVR-equipped 

vehicles are equal to or less than the 

total emissions from Stage II VRS and 

ORVR, including IEE 

2013 2013 2015 

85% of gasoline dispensed to ORVRequipped vehicles 2011 2012 2013 

90% of gasoline dispensed to ORVRequipped vehicles 2013 2014 2016 (d) 

95% of gasoline dispensed to ORVRequipped vehicles 2016 2018 2021 

As previously mentioned, if Stage II VRS is removed when the ORVR only emissions 

are equivalent to the Stage II VRS emissions [definition (c)], an increase in emissions from the 

level achieved with both ORVR and Stage II VRS controls will occur. The results from this 

analysis indicate that for the year widespread use is achieved this increase would be: 

 State Year Increase, tpsd

 

MA 2010 2.0 

NH 2008 1.0 

VT 2008 0.6 

As the penetration of ORVR-equipped vehicles increases, this difference in emissions 

between ORVR only and ORVR with Stage II and IEE decreases rapidly with each ensuing year, 

as indicated in Table 36. 
DRAFT 02-07-06

103 

Table 36. Difference in Emissions Between ORVR only and ORVR with 

Stage II VRS plus IEE 

Emissions, (tons per summer day)

Year MA NH VT

2008 0.97a 0.64a

2009 0.72 0.49 

2010 1.96a 0.47 0.36 

2011 1.00 0.25 0.25 

2012 0.24 0.10 0.15 

2013 -0.38 b -0.06 b 0.08 

2014 0.01 

2015 - -0.05 b

 

a

 Def (c): ORVR = SII 

b

 Def (c2): ORVR = SII+ORVR+IEE 

D. Algorithm Analysis Issues 

The in-use CE used in determining widespread use for definition (c) has an impact on 

how soon widespread use is reached. A higher in-use CE will result in a later widespread use 

date, while a lower in-use CE results in an earlier widespread use date. The impact of the in-use 

CE is understandable because a low in-use CE represents a Stage II VRS that is not operating as 

efficiently and effectively as the systems designed CE; therefore, as ORVR-equipped vehicles 

become more prominent in the vehicle fleet, it takes less time for ORVR technology to be more 

effective at reducing emissions. A high in-use CE for Stage II VRS delays the widespread use 

date because ORVR technology only becomes more effective at reducing emissions when the 

vehicle fleet is mostly comprised of ORVR-equipped vehicles. 

The IEE factor used in determining a widespread use date for definition (c2) impacts how 

soon the widespread use date occurs. The larger the IEE factor, the sooner the widespread use 

date will approach. Definition (c2) takes into account that there is an additional level of control 

achieved by Stage II VRS beyond the control level defined by definition (c) (i.e., when the 

ORVR control level is equivalent to the Stage II VRS control level), but this additional level of 

control is offset by IEE. As ORVR-equipped vehicles become more prominent in the fleet, the 

IEE increases; eventually the emissions from ORVR only are less than the emissions from 

combined Stage II VRS and ORVR, including IEE. For these analyses an IEE factor of 0.86 

lb/1000 gal was used (based on CARB data for a VA system with a certified A/L ratio of 1.0 to 

1.2). This emissions factor was used for all VA systems in these analyses and no attempt was 

made to adjust the factor for systems with lower A/L ratios nor for volatility of the fuel (Reid 

vapor pressure). Using a smaller IEE factor would result in a later date for widespread use 

defined by (c2). Because applying a smaller IEE factor would result in less IEE, the difference 

in total emissions between ORVR only and ORVR with stage II VRS plus IEE would increase 

(i.e., the emissions summarized in Table 36 would increase). IEE factors lower than the 0.86 

lb/1000 gal value used in these analyses have been reported for systems with lower A/L ratios 
DRAFT 02-07-06

104 

[specifically: by CARB (for Dresser Wayne VA system) and by API ( for Miniboot); See 

Section VI] 

E. Recommendations 

As discussed previously, EPA stated support for definition (c), however after examining 

the results from determining widespread use for definitions (c) and (c2), we recommend 

definition (c2). Definition (c) is less ideal than definition (c2) because it does not take into 

account the short-term increase in emissions from the removal of Stage II VRS. As ORVRequipped vehicles become more prominent in the fleet, the emissions increase from Stage II 

removal decreases and eventually the emissions from ORVR only are less than the emissions 

from combined Stage II VRS and ORVR, including IEE. Definition (c2) is complicated and is 

largely impacted by the IEE factor used in algorithm analysis. EPA believes that additional 

emissions monitoring needs to be conducted to better understand IEE. As discussed in Section 

V.D., CARB and the WSPA plan to conduct some emissions testing to better define IEE; 

however, when their testing will occur is unclear. Hertz is planning to conduct some emissions 

testing that will include UST vent emissions and tank pressure tracking. In addition, Hertz will 

be conducting testing to demonstrate that withdrawing Stage II vacuum assist VRS will not 

adversely impact VOC emissions from their GDFs. Because most of their vehicles are ORVRequipped and the Stage II VRS are vacuum assist, their test data will provide IEE data. NH 

DES, University of New Hampshire (UNH), Gilbarco/Veeder Root (GVR), and EFPAG are 

conducting an emissions monitoring project that will also provide more IEE data. We believe 

that these emissions tests will enable EPA to better quantify the IEE and indicate what IEE factor 

to use in determining widespread use. 

EPA recommends that States use the same methodologies as presented in this section to 

calculate a widespread use date. States are advised to wait until EPA has had time to examine 

the IEE data collected from upcoming testing before calculating widespread use dates. Once 

EPA has examined the IEE data, EPA will provide guidance on what IEE factor to use in 

widespread use calculations. 

VIII. Recommendations

A summary of our recommendations from the previous sections are as follows: 

 OPSG not dictate a policy on vacuum-assist versus balance for Stage II VRS. 

 OPSG continue to urge OMS to produce data for ORVR in-use long-term control 

efficiency. 

 We continue to conduct testing to determine the IEE and forward the data results to 

OPSG. 

 OPSG consider definition (c2) as the best option for determining widespread use. 

 Regarding phase out of Stage II VRS, OPSG: (1) develop guidance on the 

decommissioning of Stage II VRS; (2) allow waivers for new GDF and conduct a cost 

study to determine when new GDF are not required to install Stage II VRS; and (3) 

develop guidance on other control measures, control efficiencies, and costs. 
DRAFT 02-07-06

105 

 OPSG recommend P/V valves for all UST vents nationwide for additional HAP control. 

 Regarding phase out in the OTR: (1) same recommendations as above for Stage II VRS 

in other States; (2) OPSG provide the mechanism to phase out section 184(b)(2) 

requirements for Stage II VRS by updating or amending the Stage II Comparability 

Study, or other acceptable means. 

 OPSG develop guidance for awarding SIP credits to GDF owners/operators who provide 

additional control for the three categories including, (1) new GDF; (2) GDF that remove 

Stage II VRS; and (3) other large-emitting GDF.

 OPSG consider adopting some components of CARB’s EVR.

 OPSG recommend use of ISD and increased inspections.

 Provided adequate funding is available, we update emissions factors based on emissions 

measurement data.

 OPSG draft and release memorandum indicating our acceptance of waivers for Rental 

Car Facilities and Automobile Manufacturers. 

 OPSG consider additional control measures that focus on alleviating UST pressurization 

and thus reducing MTBE groundwater contamination.

 We continue to conduct testing to determine the magnitude of UST emissions (both vent 

and fugitive) and provide the data results to OPSG. 
Appendix A 

Brief Summaries of Data Provided by Stakeholders 

1
Previous Data Collected by EPA 

SUMMARY OF EXCESS EMISSION DATA 

This summary presents the key data and conclusions from several studies conducted to evaluate 

excess emissions created from the refueling of Onboard Refueling Vapor Recovery (ORVR) 

equipped cars at Gasoline Dispensing Facilities (GDF) using vapor recovery systems (VRS). For 

each data source: (1) the tests conducted are described, (2) key results and conclusions presented 

in the data sources are summarized, and (3) a table of the data is presented. The table is 

organized to identify the actual measurements conducted and results reported in the study. 

GENERAL NOTES 

EPA defines refueling emissions as the evaporative loss emissions during refueling, as 

well as emissions from spillage. For the purposes of this summary, spillage emissions are not 

addressed and reference to “refueling emissions” does not include spillage. 

Emissions may occur (and may be measured or calculated) at numerous points within the 

system. CARB’s VRS certification test method, TP-201.2, addresses making measurements or 

calculating emissions from several points in the system. The measurement points are: 

1. Emissions at nozzle/vehicle interface (“fill pipe” emissions) 

2. VOC’s returned through the vapor passage of the hose 

3. Emissions from the UST P/V valve 

4. Emissions from the assist processor (not applicable in these studies), and 

5. Calculated pressure-related fugitives based on UST tank pressure measurements 

The emissions data generally are reported as lb VOC/1000 gallons dispensed. Note that 

in the actual reports both lb VOC/1000 gallons dispensed and g VOC/gal dispensed were used; 

this often got confusing as the authors switched back and forth. The figures from the reports that 

are presented along with this summary typically use g VOC /gallons dispensed, whereas the data 

in the summary table is presented in lb/1000 gallons. 1 lb/1000 gallons = 0.454 g/gallon 

(roughly, there are 2 lb/1000 gallon per g/gallon). 

SOURCES 

[1] 	 CARB: Preliminary Draft Test Report, “Total Hydrocarbon Emissions from Two Phase II 

Vacuum Assist Vapor Recovery Systems During Baseline Operation and Simulated 

Refueling of Onboard Refueling Vapor Recovery (ORVR) Equipped Vehicles”, June 

1999 

•	 Tests conducted in August/September 1998 at two facilities with Vacuum 

Assist(VA) VRS. to quantify “excess emissions” from vapor growth 

•	 At time of tests, these two types of systems represented 80% of VA systems in 

CA, and dispense 55% of gasoline purchased 

•	 VRS emissions were determined from direct measurement of UST pressure/ 

vacuum (P/V) valve emissions and calculation of fugitive emissions based on 

UST pressure readings 

2
•	 CARB did not measure or attempt to quantify the emissions at the nozzle/fill pipe 

interface (“fillpipe emissions”) during the study 

•	 Testing had two phases: 1) “baseline” normal operations and 2) simulated 

ORVR (mix of 40% ORVR vehicles). Because ORVR vehicles were not 

prevalent when tests were done, the refueling of ORVR was simulated by 

modifying the dispensers to ingest ambient air. 

Key Results: 

•	 Negligible emissions emitted from the P/V valve when P/V valve in operation; 

fugitives were from other unknown locations (e.g. leaks) 

•	 Excess emissions did occur (calculated pressure related fugitives) when refueling 

with the simulated ORVR scenario. See table 1 for details. Ultimately, CARB 

used these data to develop an average excess emissions factor of 0.86 lb/1000gal 

when refueling ORVR equipped vehicles with VA VRS. 

[2]	 API: ORVR Compatibility Study for the Gilbarco Vaporvac VRS, February 2004; 

Phase 1 

• ORVR compatibility study at a GDF in California. 

• The fuel was summertime reformulated federal gasoline (RVP 7.0) 

• The vapor recovery system was vacuum assisted (Gilbarco). 

•	 Used CARB Stage 2 certification test procedure TP201.2. Figure 2-1 identifies 

the measurement points. The measurement points are: 

1) Emissions at nozzle/vehicle interface (“fill pipe” emissions); 

2) VOC’s returned through the vapor passage of the hose; 

3) Emissions from the UST P/V valve; 

4) Emissions from the assist processor (not applicable in these studies), 

and 

5) Calculated pressure related fugitives based on UST tank pressure 

measurements. 

• Test 1: 100 car matrix, standard VA nozzles 

• Test 2: 100 car matrix, nozzles with “miniboots,” to limit influx of ambient air 

Key Results: 

• Overall pressure related emissions: 

• Test 1 (standard nozzle): 1.38 lb/1,000 gal 

• Test 2 (miniboot): 0.494 lb/1,000 gal. 

•	 Therefore, Miniboot reduces pressure related emissions by 0.886 lb/1000 

gal (64 percent) 

•	 Could not differentiate (quantify) the effects of ORVR vs non-ORVR vehicles on 

UST pressures and UST vent emissions due to interferences from vehicles 

simultaneously refueling at other pumps connected to tanks 

•	 Emissions from the fill pipe were measured. ORVR vehicles reduce emissions 

from the nozzle/fillpipe interface by 0.31 lb/1,000 gal. Therefore, it is concluded 

that the CARB “ORVR excess emission factor” due to vapor growth (0.86 

lb/1,000 gal) should be offset accordingly; i.e., total excess emissions are 0.86 

3
lb/1,000 gal - 0.31 lb/1,000 gal or 0.55 lb/1,000 gal. 

[3]	 API: ORVR Compatibility Study for the Gilbarco Vaporvac VRS, February 2004, 

Phase 2 – Outside 

•	 Outdoor tests using 3000 gallon UST containing 1000 gallons in a laboratory 

setting 

• RVP: 7.8 summer grade oxygenated 

• Six refueling tests on 3 vehicles (two with ORVR and one without ORVR) 

•	 Measured UST fugitives from P/V vent & pressure related fugitives (the system 

was first demonstrated to be leak free; then a fugitive leak rate was controlled 

using a calibrated needle valve) 

•	 Compared fugitives measured while refueling ORVR & non-ORVR vehicles to 

determine incompatibility excess emissions 

•	 Compared pressure related fugitives actually measured to those predicted by 

CARB calculations 

Key Results:


For standard nozzle:


• Pressure related excess emissions were calculated to be 0.72 lb/1000 gal. 

•	 Fill pipe emissions for ORVR equipped vehicles were 0.39 lb/1000 gal less than 

for non-ORVR vehicles (91% reduction) 

•	 Adjusted (“net”) ORVR excess emissions were 0.33 lb/1000 gal. [i.e., pressure 

related excess emissions minus the savings at the fill pipe = 0.72-0.39] 

•	 If using these corrections on data generated from MOBILE6, the correct excess 

emission factor to use is 0.42 lb/1000 gal (not 0.33 lb/1000 gal) because MOBILE 

6 already accounts for some of the fill pipe reductions achieved by ORVR 

equipped vehicles by using a 98% control efficiency for ORVR rather than the 

95% efficiency for VRS. 

For miniboot: 

• Pressure related excess emissions were calculated to be zero (-0.008) lb/1000 gal. 

•	 Fill pipe emissions for ORVR equipped vehicles were less than for non-ORVR 

vehicles 

•	 Adjusted (“net”) ORVR excess emissions were -0.39 lb/1000 gal; i.e., a decrease 

in emissions [zero pressure related excess emissions minus the savings at the fill 

pipe = a reduction of 0.39 lb/1000 gal]. 

[4]	 API: ORVR Compatibility Study for the Gilbarco Vaporvac VRS, February 2004, 

Phase 2 – SHED 

• Conducted in Sealed Housing for Evaporative Emissions (SHED) 

•	 Thirty-six refueling tests using procedures similar to the federal ORVR 

certification test; 

• Three vehicles (two ORVR, one non-ORVR) 

• First checked (validated) ORVR performance (i.e., baseline certification) 

• Investigated impact of: 

• RVP 7.1 & 7.8; 

4
•	 Temperature: three summertime temperature scenarios (one vapor 

growth and two vapor shrinkage scenarios) by varying the 

temperature of the fuel dispensed and vehicle tank) 

• A/L ratios (standard nozzle & miniboot); 

• Type of ORVR equipment (recirculation or not) 

Key Results: 

•	 Fill pipe emissions for ORVR and non-ORVR vehicles fall within the range of 

values measured in the Phase 1 and Phase 2 - outdoor tests. 

•	 Fill pipe emissions for ORVR equipped vehicles were 0.46 lb/1000 gal less than 

for non-ORVR vehicles 

•	 For ORVR equipped vehicles, fill pipe emissions are insensitive to changes in 

RVP, delta T, and A/L ratio; there is a positive correlation of fill-pipe emissions 

with vehicle tank temperature 

•	 For non-ORVR vehicles, there is a positive correlation of fill-pipe emissions with 

RVP, a negative correlation of fill-pipe emissions with A/L ratio, and a negative 

correlation of fill-pipe emissions with delta T, as assumed in MOBILE 6 

•	 fill-pipe emissions for the miniboot (A/L =0.95) were greater than (about 

double) the fill pipe emissions with the standard nozzle (A/L =1.15) 

•	 the emissions are greater for the vapor growth scenario (temperature of 

fuel in vehicle tank is less than temperature of fuel being dispensed) 

•	 “Puff” losses (the puff of emissions when the gas cap is removed) are the same 

order of magnitude as fill-pipe emissions for both ORVR and non-ORVR 

equipped vehicles 

5
SUMMARY OF EXCESS EMISSION DATA 

All emission units are lb/1000 gals dispensed or [g/gal] unless otherwise noted 

Data 

Source 

Unit Type/ 

Test conditions 

Fill Pipe 

Emissions 

(a) (b) 

P/V Vent 

Emission 

(c) 

Calculated 

Pressure 

Related 

Fugitives 

(leaks) 

(d) 

Total 

Pressure 

Related 

emissions 

(e = c+d) 

Total 

Refueling 

emissions 

(f =b+c+d) 

Excess 

Emission 

due to 

ORVR 

Incomp. 

(g) 

ORVR 

Emission 

reduction at 

fill pipe 

(h) 

Adjusted 

Excess 

Emission 

due to 

ORVR 

Incomp. 

(i) 

CARB [1] 

Scenario 1 

Gilbarco VA 

Baseline: Not 

measured 

Negligible 0.396 

Not 

measured 

Gilbarco VA 

ORVR: 

0.782 0.386 

CARB [1] 

Scenario 2 

Dresser Wayne 

Baseline: 

Not 

measured Negligible. 

0.028 

Dresser Wayne 

ORVR: 

0.0524 0.0244 Not 

measured 

CARB [1] 

Scenario 3 

Dresser Wayne 

(without 

P/V valve) 

Baseline: 

Not 

measured 

Negligible 0.026 0.026 

Dresser Wayne 

(without 

P/V valve) 

ORVR: 

0.289 0.289 0.263 Not 

measured 

CARB 0.86 

6
7

Data 

Source 

Unit Type/ 

Test conditions 

Fill Pipe 

Emissions 

(a) (b) 

P/V Vent 

Emission 

(c) 

Calculated 

Pressure 

Related 

Fugitives 

(leaks) 

(d) 

Total 

Pressure 

Related 

emissions 

(e = c+d) 

Total 

Refueling 

emissions 

(f =b+c+d) 

Excess 

Emission 

due to 

ORVR 

Incomp. 

(g) 

ORVR 

Emission 

reduction at 

fill pipe 

(h) 

Adjusted 

Excess 

Emission 

due to 

ORVR 

Incomp. 

(i) 

API [2] 

Test 1 

Gilbarco VA 

Standard nozzle 

(OPW 11VA1); 

non-ORVR 

0.42 

0.823 0.557 1.38 

Gilbarco VA 

Standard nozzle 

(OPW 11VA1); 

ORVR vehicles 

0.11 Not 

measured 

0.31 

(73% less 

than nonORVR) 

API [2] 

Test 2 

Gilbarco VA 

With “miniboot” 

(OPW 12VW); 

non-ORVR 

0.42 

0.008 0.484 0.494 

Gilbarco VA 

With “miniboot” 

(OPW 12VW); 

ORVR vehicles 

0.11 Not 

measured 

0.31 

(73% less 

than nonORVR) 
Data 

Source 

Unit Type/ 

Test conditions 

Fill Pipe 

Emissions 

(a) (b) 

P/V Vent 

Emission 

(c) 

Calculated 

Pressure 

Related 

Fugitives 

(leaks) 

(d) 

Total 

Pressure 

Related 

emissions 

(e = c+d) 

Total 

Refueling 

emissions 

(f =b+c+d) 

Excess 

Emission 

due to 

ORVR 

Incomp. 

(g) 

ORVR 

Emission 

reduction at 

fill pipe 

(h) 

Adjusted 

Excess 

Emission 

due to 

ORVR 

Incomp. 

(i) 

API[3] Outdoor test 5; 

Standard nozzle 

non-ORVR 

1.53 

(check) 

0 (Measured) 

0.022 

(Measured) 

0.022 

NA 

Outdoor test 1; 

Standard nozzle 

ORVR vehicle 

with recirc. 

0.024 0 (Measured) 

0.918 

(Measured) 

0.918 

0.896 

Outdoor test 3; 

Standard nozzle 

ORVR vehicle 

without recirc. 

0.026 

(check) 

0 (Measured) 

0.229 

(Measured) 

0.229 

0.207 

Standard nozzle 

ORVR vehicle, 

wgt. 

(calculated) 

0.025 0.745 (k) 0.7 2 (k) 0.39 (m) 

(91% less 

than nonORVR) 

0.33 

API[3] Outdoor test 6; 

Miniboot; 

non-ORVR 

2.11 0 (Measured) 

0.011 

(Measured) 

0.011 

NA 

Outdoor test 2; 

Miniboot; 

ORVR vehicle 

with recirc. 

0.002 0 (Measured) 

0.004 

(Measured) 

0.004 

- 0.007 

Outdoor test 4; 

Miniboot; 

ORVR vehicle 

without recirc. 

not 

available 

0 (Measured) 

0.002 

(Measured) 

0.002 

- 0.009 

Miniboot; 

ORVR vehicle, wgt 

average 

(calculated) 

0.003 (k) -0.008 (k) 0.39 (m) 

(91% less 

than nonORVR) 

-0.39 

i.e., zero 

8

average 
Data 

Source 

Unit Type/ 

Test conditions 

Fill Pipe 

Emissions 

(a) (b) 

P/V Vent 

Emission 

(c) 

Calculated 

Pressure 

Related 

Fugitives 

(leaks) 

(d) 

Total 

Pressure 

Related 

emissions 

(e = c+d) 

Total 

Refueling 

emissions 

(f =b+c+d) 

Excess 

Emission 

due to 

ORVR 

Incomp. 

(g) 

ORVR 

Emission 

reduction at 

fill pipe 

(h) 

Adjusted 

Excess 

Emission 

due to 

ORVR 

Incomp. 

(i) 

API[4] SHED 

Standard nozzle 

Non - ORVR 

0.32 

SHED 

Standard nozzle 

ORVR 

with recirc. 

0.057 

SHED 

Standard nozzle 

ORVR 

without recirc 

0.007 

SHED 

Standard nozzle 

ORVR Vehicle 

Wgt Avg. (calc.) 

0.045 0.275 

API[4] SHED 

Mini-boot 

Non - ORVR 

0.69 

SHED 

Mini-boot 

ORVR 

with recirc 

0.054 

SHED 

Mini-boot 

ORVR 

without 

0.007 

SHED 

Mini-boot 

ORVR Vehicle 

Wgt Avg. (calc) 

0.041 0.649 

9

recirc 
10

Data 

Source 

Unit Type/ 

Test conditions 

Fill Pipe 

Emissions 

(a) (b) 

P/V Vent 

Emission 

(c) 

Calculated 

Pressure 

Related 

Fugitives 

(leaks) 

(d) 

Total 

Pressure 

Related 

emissions 

(e = c+d) 

Total 

Refueling 

emissions 

(f =b+c+d) 

Excess 

Emission 

due to 

ORVR 

Incomp. 

(g) 

ORVR 

Emission 

reduction at 

fill pipe 

(h) 

Adjusted 

Excess 

Emission 

due to 

ORVR 

Incomp. 

(i) 

API [4] SHED 

Vehicle 3 

Non - ORVR 

PUFF (n) 

0.321 

SHED 

Vehicle 1 

ORVR 

with recirc 

PUFF (n) 

0.030 

SHED 

Vehicle 2 

ORVR 

without recirc 

PUFF (n) 

0..007 

API [4] Vehicle 1: ORVR 

Certification 

0.017 

[0.008] 

API[4] Vehicle 2: 

Certification 

0.002 

[0.001] 

EPA Standard for 

ORVR 

0.44 

[0.20] 

(Includes 

spillage) 

ARID [5] Non-ORVR and 

ORVR autos 

[0.0458] 

for nonORVR; 

[0.0092] 

for ORVR 

Not 

Reported 

(?) 

Not 

Reported 

(?) 

Not 

Reported 

(?) 

Or 0.042?, 

based on 

what Roy 

did for the 

API [2] 

results? 

Not 

Reported 

(?) 

0.042 (Roy 

put this 

parameter 

in the 

“Pressure 

Releated 

Fugitives” 

column, 

when 

dealing 

with API 

[2] 

0.0805 

[0.0366] 

-0.0385(?) 

(May be 

wrong, if 

the 

“0.042" 

belongs in 

the 

“Pressure 

related 

fugitives” 

column 

ORVR 
= measured fill pipe displacement emissions for non-ORVR vehicles -measu red fill pipe dis

(a) Refueling emissions = fill pipe displacement + spillage per EPA definition; spillage not addressed in these data 

(b) Fill pipe emissions = fill pipe displacement emissions 

(c) P/V vent emissions = emissions from UST vent pressure /vacuum valve 

(d) Calculated pressure related (PR) fugitive emissions from VRS leaks per CARB calculation method 

(e) Total pressure related emissions = P/V vent emissions + PR fugitives 

(f) Total refueling emissions = total refueling emissions by CARB test method = Fill pipe displacement + P/V vent emissions + calcula

(spillage estimated separately or by performance standard of nozzle?) 

(g) Excess emissions due to ORVR incompatibility = total pressure related emissions for ORVR - total pressure related emissions for n

Note: the API report refers to excess emissions of pressure-related fugitives separately from P/V emissions 

-ORVR emissi ons reductions ach

Note: the API report refers to this as “total incompatibility emissions” 

(j) Average hydrocarbon concentration in the VRS return line. 

(k) Weighted average of ORVR with and without recirculation; assumes 75% of ORVR vehicles have recirculation. 

(m) Average of Phase 1 (in-field) tests and SHED tests 

(n) PUFF = puff of emissions that occur when gas cap is removed; measured quantity normalized to gallons dispensed 

NA = Not Applicable 

(i) Total adjusted excess emissions = pressure related excess emissions due to ORVR incompatibility 

(h) ORVR emission reductions at fill pipe 

ORVR vehicles 

NOTES 

11
Source Company/Organization (include Title and date): 

Phase II Balance System Test Report, Lincoln Test Site. Husky Corporation, Franklin 

Fueling Systems. June 2005. (Data from February 1 to March 21, 2005). [Submitted by 

Husky Corporation] 

Test Scenario (Describe): 

The GDF tested is a balance Stage II VRS. The test was conducted to conclude whether an UST 

vent add-on APCD (i.e., a processor) would be necessary on the balance system to be compliant 

with the EVR UST pressure requirements (CP-201). The test studied the effects of the GDF that 

shut down each night for 6 hours while operating with high RVP winter fuel and with lower RVP 

fuel. A total of 121,000 gal was dispensed over the testing time period. An ISD system was in 

place. Redundant monitoring was in place. The ISD collected data on system pressure, ullage 

data, and the nozzle fuel and vapor (V/L ratio), and CARB collected data on system pressure, 

barometric pressure, RVP, Static pressure decay test, Dynamic back pressure test, liquid 

extraction functionality by hose drainage, and ORVR penetration percentage. 

Based on tracking ORVR activity over a 13-hour period, 41 percent of gasoline throughput went 

to ORVR vehicles (1,540 gal/3,745 gal). So, the balance VRS collected vapors for 59 percent of 

the fuel dispensed, and ORVR controlled the vehicle refueling vapors for 41 percent of the fuel. 

For comparison purposes, the percentage of ORVR vehicles was 42 percent (149/354). 

Emissions Testing: 

None. 

Operating Data: 

Testing was conducted from February 1 through March 21, 2005. Winter fuel (high RVP) was


used during the time period February 1 through 28; lower RVP fuel was used during March 1


through 21. 


Results and Conclusions Reported:


Pressure decay tests were conducted weekly. The system passed these tests, however, on


February 22 the pressure decay test failed; without modification or maintenance, the tank then


passed the pressure decay test on February 28. The data from February 16 through February 28


was suspect and was excluded from the test and analysis.


Pressures and temperatures were monitored continuously. These data indicate both (1) that the


system is leak free and (2) the amount of emissions that would be sent to a processor if one were


in place (i.e., any positive pressure greater than 0 in. w.c.). [Note that no vapor was actually


vented from the UST because the P/V valve was in place and would not open unless pressure


reached 3 in. w.c.; it did not over the 36-day period.] The system remains at significant negative


pressure for long periods (exceeding 8 hours) and this would also indicate the system is tight (in


addition to the pressure decay tests above). There were 3 days when the pressure flat-lined or


remained at 0 in. w.c. for a length of time, indicating a possible leak. Each of these events was


explained and/or corrected. The amount of emissions that would be sent to a processor was


calculated from the total time when UST pressures were above 0 in. w.c. The UST fugitive and


12
vent emissions were calculated to be 7.7 lb of HC and this was extrapolated to an annual basis of 

48 lb/yr that would be controlled by a processor (if one were in place). 

During the 36-day testing period, the CARB daily average pressure was exceeded on 3 days and 

the 30-day average pressure was 0.04 in. w.c. (compared to the allowed 0.25 in. w.c.) The daily 

hourly maximum pressure was exceeded on 2 days, and the 30-day average hourly maximum 

pressure was 0.32 in. w.c. (compared to 1.5 in. w.c.). The test demonstrates that the balance 

system meets the pressure profile requirements of CARB’s EVR CP-201, without the use of a 

processor. 

A comparison of the pressures resulting from the high and low RVP fuels was also conducted. 

For shutdown periods (early morning hours when pressures will be highest), the daily average 

pressure dropped from -0.04 in. w.c. to -0.45 in. w.c. with the lower RVP fuel. Additional 

analysis was conducted to compare the UST pressures for the two RVP. The analysis was 

conducted on a subset of data, specifically for those shut down hours when no fueling is being 

conducted at the GDF. For the shutdown periods only, the 30-day rolling daily average was 0.35 

in. w.c. for RVP of 13 psi and was 0.055 in. w.c for RVP of 9 psi. The 30-day rolling average 

hourly maximum pressure was 2.4 in. w.c. for RVP of 13 psi and was 0.51 in. w.c. for RVP of 9 

psi. A summary table for each RVP is provided. 

The V/L ratios were also measured for each of the 12 fueling points. The daily averages ranged 

from 0.34 to1.66 across the fueling points (the sensors at 2 of the fueling points failed and are not 

included). The average V/L ratios over the 36-day period for each fueling point ranged from 0.71 

to 1.0. 

Comments: 

The pressures experienced by the balance system are generally low and the system does not 

experience vapor releases. These systems appear to be vapor tight because significant negative, 

and occasional positive, pressures are maintained in the tank over long periods (several hours and 

longer) and few to no periods are shown at 0 in. w.c. (if there were, this would indicate leaks). 

For the majority of time, the UST tank is at negative pressure. The negative pressures reduce the 

potential for UST fugitives emissions and UST venting emissions. Positive pressure periods 

were seen during the study but the frequency, magnitude, and duration are low. Emissions from 

the positive pressure periods were estimated to be 48 lb/yr. 

13
Daily Summary of Pressure Data for Friday, March 11, 2005 

14
Daily Summary of Pressure Data for Saturday, March 12, 2005 

15
Daily Average Nighttime (2300 to 0500) System Pressures with High RVP Fuel (~13 psi). 

16
Daily Average Nighttime (2300 – 0500) System Pressures with Low RVP Fuel (~9 psi). 

17
Source Company/Organization (include Title and date): 

UST pressure monitoring data at a GDF in Sacramento, CA. January and August 2004. 

[Submitted by Healy, Inc.] 

Test Scenario (Describe): 


The GDF has a Healy vacuum assist Enhanced Vapor Recovery (EVR) Stage II VRS and a


Clean Air Separator on the UST; this system is ORVR compatible. An ISD system is also


installed.


Emissions Testing: 

None. 

Operating Data: 

UST pressure measurements were shown with and without the Clean Air Separator operating. 

Pressure data are shown for: 

(1) summer fuel in August (August 11-17) without the Clean Air Separator operating,


(2) for summer fuel in August (August 25-31) with the Clean Air Separator operating


with a simulated fugitive leak, and


(3) for winter fuel in January (December 31-January 20) with the Clean Air Separator


operating.


The Clean Air Separator is a tank with an expandable bladder that accepts vapor from the UST 

and reduces UST vent emissions and UST fugitive emissions that result from positive pressures. 

When UST pressures exceed +0.15 in. w.c., the UST vents to the flexible bladder where the 

vapor is contained. The conversion of a vacuum assist Stage II VRS to an ORVR compatible 

Stage II VRS includes replacing the vacuum source (pump), hose assembly, and the nozzle. 

Results and Conclusions Reported: 

Without the UST Clean Air Separator in place (August 11-17 data), the pressures range from 

approximately -9 in. w.c. to +3 in. w.c. During operating hours when the GDF was dispensing 

fuel from the UST, the UST pressures decreased and significant negative pressures were 

maintained. During nighttime hours when the GDF would be closed and not operating, there was 

consistent pressure increase, indicating vapor growth. The pressures during off-hours were often 

above 0 in. w.c., indicating pressurization of the tank and possible fugitive emissions. The 

pressures rose to +3 in. w.c. on some nights, indicating P/V valve venting and UST vent 

emissions and UST fugitive emissions as well. 

The August 25-31 pressure data graphs with the UST Clean Air Separator and with a simulated 

fugitive leak show pressures range from -8 in. w.c. to approximately 0 in. w.c. There were a few 

momentary spikes in pressure (as high as +4.5 in. w.c.) with return to 0 in. w.c. During offhours, there was consistent pressure increase, indicating vapor growth. There are minimal 

episodes above 0 in. w.c. because the UST is vented to the flexible bladder at +0.15 in. w.c. (If 

the Clean Air Separator was not in place, significant positive pressures would not be maintained 

due to the leak that was simulated during this testing scenario.) During operating hours, the UST 

18
pressures decrease to significant negative pressures, however, with the simulated leak, not as 

much vacuum is pulled on the UST (i.e., the pressures do not appear to be as negative as shown 

in the “tight” UST data above). 

With the UST add-on APCD in place (January data), the pressure ranges from approximately -9 

in. w.c. to just above 0 in. w.c. During operating hours when the GDF was dispensing fuel from 

the UST, the UST pressures decrease and significant negative pressures are maintained. During 

nighttime hours when the GDF would be closed and not operating, there was consistent pressure 

increase, indicating vapor growth. However, there are minimal episodes above 0 in. w.c. because 

the UST vents to the flexible bladder at +0.15 in. w.c. There are a few momentary spikes in 

pressure with immediate return to 0 in. w.c. The daily average V/L ratio at the two pumps for the 

January time period ranged from 0.95 to 1.1 over this time period. 

Comments: 

Based on these data, the Healy EVR system with the Clean Air Separator on the UST does limit 

positive pressure periods in the UST, reducing the potential for fugitive emissions and reducing 

UST venting periods that occur when the pressure rises to +3 in. w.c. or greater. Significant 

negative pressures are maintained during operating (i.e., dispensing) hours. 

19




Source Company/Organization:


Summary of the Evaluation for Phase II Balance Type Vapor Recovery Systems


Interacting with On-Board Refueling Vapor Recovery (ORVR) Equipped Vehicles. Data


collected in December 2002. [Submitted by EMCO Wheaton Retail]


Test Scenario: 


The GDF has a balance Stage II VRS. Pressure measurements of the UST were taken from


December 4-10 in California. The vehicles refueled at the facility were 100 percent ORVR. The


GDF closes for 8 hours per day.


Results and Conclusions Reported:


The pressures in the UST ranged from -2.6 iwc to +0.15 iwc over a 7-day period. A total of 486


vehicle fuelings were conducted and a total of 2,816 gal were dispensed. The pressures seemed


consistent with typical UST pressures for refueling with higher pressure during nighttime hours


when the GDF was closed and not dispensing fuel and with negative pressures during operating


hours when the GDF is dispensing fuel (although the dates and times were not specifically


delineated on the graph). The UST pressures were less than or equal to 0 iwc for 95 percent of


the operating time and was greater than 0 iwc and less than +0.25 for 5 percent of the operating


time.


The pressure data indicate that the balance Stage II VRS used to fuel ORVR vehicles will not 

generate excess emissions from the UST due to ORVR refuelings. Because the UST pressures 

are negative most of the time with a small amount of time at positive pressures, fugitive 

emissions and UST vent emissions are minimized. 

Comments: 

None. 

24

Source Company/Organization:


Test Report for the Arid Technologies Vapor Recovery Unit Installed at the Costco


Gasoline Station, Lantana, Florida. Testing conducted in February 2005. The draft report is


undated (appears to be circa March 2005). 


Test Scenario:


Emissions testing was conducted at the Costco retail gasoline station to demonstrate the capture 

efficiency of an UST add-on APCD on the UST and to compare the UST vent stack emissions 

when the add-on APCD is operating (on) and not operating (off). The GDF has a vacuum assist 

Stage II VRS. The add-on APCD is Arid Technologies Inc. vapor control unit called the 

PERMEATOR.® This device is used to control VOC emissions from the UST vent during 

gasoline dispensing operations. The PERMEATOR® is a membrane system that allows gasoline 

vapors to pass through and back to the UST; air is prevented from permeating the membrane and 

is vented to the atmosphere. 

The test period was continuous and lasted approximately 72 hours. Sampling was conducted at 

the outlet vent of the USTs when the add-on APCD was not operating. Sampling was conducted 

at three locations on the add-on APCD while it was operating. Testing was conducted with and 

without the P/V valves in place; these conditions are referred to in the test report as “Vent Off” 

and “Vent On,” respectively. The number of ORVR vehicles fueled at the facility during the 

testing periods is not known. 

Operating Data: 

A graph of UST pressure data for periods with and without the add-on APCD (and with the P/V 

in place) is provided. While the add-on APCD was operating, the UST pressure is maintained at 

approximately 0.5 in. w.c with the majority of measurements ranging from 0.3 to 0.9 in. w.c. 

Venting to the add-on APCD occurs when pressures within the tank reach approximately 0.5 in. 

w.c. While the add-on APCD is operating, the P/V valve never opens because the UST does not 

reach sufficient pressure, so there are no UST vent emissions. In addition, because pressurization 

above approximately +0.5 in. w.c. does not occur, UST fugitive emissions may also decrease. 

When the add-on APCD is not operating, the pressures are typically at approximately 3.3 in. w.c. 

The UST pressure will increase to approximately 3 in. w.c. and then the P/V valve will open to 

release the pressure and gasoline vapors to the atmosphere. UST vent emissions are occurring in 

addition to UST fugitive emissions. 

Results and Conclusions Reported: 

Test results were as shown in the table below. 

26
APC D off 

with P/V valve 

APCD on 

with P/V valve 

Emissions Testing Results for UST Vent Add-on APCD. 

Test Conditions 

Te st Date 

Gasoline Loaded, gal 

Average Inlet Concentration, % C3 

Average Outlet Concentration, % C3 

Average Hydrocarbon Emission, 

lbs/1000 gal 

Hydrocarbon Emission Rate, 

lb/24hr 

Hyd roca rbo n Remov al Efficien cy, 

% (m ass basis) 

Amb ient T, °F 

UST tempera ture, °F 

RV P, psia 

V/L ratio ** 

Fueling rate, ga l/min 

Per cent O RV R vehicles fue led, % 

APCD off 

without P/V valve 

February 14-15, 2005 

19,186 

NA 

39.79 

3.48 

66.84 

NA 

71°F 

74°F 

11.1 

0.97 

8 

February 16-17, 2005 

18,908 

NA 

41.58 

1.20 * 

22.75 * 

65.5% * 

71°F 

74°F 

11.1 

0.97 

8 

February 15-16, 2005 

19,121 

38.52 

0.72 

0.014 

0.27 

99.3% 

71°F 

74°F 

11.1 

0.97 

8 

Not known Not known Not known 

* Due to a leak, fugitive emissions were released to the atmosphere during UST pressurization periods; the amount 

of fugitive emissions (i.e., gasoline vapors) released are not quantifiable. 

** The V/L ratio was calculated based on an average for regular gasoline only, at fueling points 7 through 12 while 

the GDF was closed and on fueling points 1 through 6 while the GDF was open. The majority of gasoline pumped 

during the test was regular fuel. 

Comments: 

The testing demonstrates that the P/V valve may reduce UST vent emissions. When P/V valves 

were not in place, emissions were 3.48 lbs/1,000 gal (66.84 lb/24hr). When the P/V valve was in 

place, emissions were reduced to 1.20 lbs/1,000 gal (22.75 lb/24hr); while the UST vent 

emissions may have been reduced, there were fugitive emissions occurring due to UST system 

leaks during this test due to vapor growth and pressurization of the tank. The amount of fugitive 

emissions, (i.e., gasoline vapor leaks) were not quantified but would likely show similar 

emissions levels to the uncontrolled scenario for the UST vent emissions (no P/V valve, with no 

add-on APCD). 

The testing demonstrates that the UST add-on APCD, the PERMEATOR® membrane system, 

was effective in separating gasoline vapor from air and returning the vapor to the UST, thereby 

reducing UST vent emissions to the atmosphere. With the add-on APCD operating, UST vent 

emissions were reduced to 0.014 lb/1,000 gal (0.27 lb/24hr); the calculated control efficiency 

(mass basis) was 99.3 percent. The Permeator system also limits positive pressures in the UST, 

27
reducing the potential for fugitive emissions and reducing UST venting periods that occur when 

pressure rises to +3 in. w.c. or greater. 

28
29
Source Company/Organization (include Title and date): 

Husky MO/PETP Testing Final Report, Citgo Express Mart, Festus, Missouri. July 1997 

through March 1998. Prepared by Environmental Solutions, Inc., for the Missouri 

Department of Natural Resources (MDNR). [Submitted by RSA] 

Test Scenario (Describe): 

The Citgo Express Mart uses a balance Stage II VRS with P/V valves on the UST vents. There 

are 3 USTs manifolded together. During the test period, two Husky nozzles were tested. Husky 

nozzle model 5210, V long was tested with an 109-vehicle matrix, while Husky nozzle model 

5010, V short was tested with an 107-vehicle matrix. 

Emissions Testing Data: 

The following MO/PETP tests were conducted: 

•	 Bench Testing (MO/TP-201.2B) - requires bench testing of nozzles, P/V valves, 

drain valves for transition flow, and leak rates 

• Dynamic Pressure (Back Pressure) Testing (MO/TP-201.4) 

• Static Pressure (Leak Decay) Testing (MO/TP-201.3) 

• Liquid Removal Test (MO/TP-201.6) 

• Stage I Efficiency Test (MO/TP-201.1) 

• Stage II Efficiency Test (MO/TP-201.2) 

• Spillage and Pseudo-Spillage (MO/TP-201.2C) 

The liquid removal test had not been previously performed in Missouri. This test proved to be 

difficult and questions regarding the validity and applicability of some of the test procedures 

came to light. The State agency felt that the test problems were not significant to the overall test 

program, and the agency decided to rewrite the test method. 

Operating Data: 

Continuous T and P data were taken for a 180-day period as part of the testing; these data include 

T and P of the UST, ambient temperatures, barometric pressure but were not provided as part of 

the report. 

Results and Conclusions Reported: 

Test results are summarized in the table below. The balance Stage II VRS at the Citgo Express 

Mart passed the overall efficiency at 97 percent (the overall efficiency for Missouri is based on 

the Stage I, vehicle refueling, spillage, and UST emissions). Both Husky nozzles were 

recommended for approval to be used with other approved balance VRS. 

30
Table 1 - Summary of Stage I and Stage II Test Results 

Efficiency Relative to 

Uncontrolled System 

Source 

Loading 

(Stage I) 

13.6 

[AP-42 E F equation] 

0.0 

[measured] 

0.0 

[measured] 

100% 100% 

Vehicle Fueling 14.6 

[AP-42 E F equation) 

0.64 a 

[emissions 

mea surem ent] 

0.63 a 

[emissions 

mea surem ent] 

95.6% 95.7% 

Spillage/PseudoSpillage 0.46 0.083 

[measured] 

0.10 

[measured] 

82.0% 78.3% 

Breathing (Pressure 

Related Fugitives 

from com pon ents 

such as P/V valves 

and no zzles) 

1.00 

[AP-42 EF] 

0.16 

[calculated] 

0.16 

[calculated] 

84.0% 84.0% 

TOTAL 29.7 0.88 0.89 97.0% 97.0% 

Uncontrolled 

System 

(without VRS) 

lbs/1,000 gal 

Pump 9 

Husky 5010 

(V Short), 

lbs/1,000 gal 

Pump 10 

Husky 5210 

(V Long), 

lbs/1,000 gal 

Pump 9 

Husky 5010, 

(V Sho rt) 

Pump 10 

Husky 5210, 

(V Long) 

a A portion of this value was due to evaporation of liquid droplets on the nozzle after completion of each fueling event and 

really belongs in the spillage/pseudospillage category. 

Comment: 

The summary did not specify if any of the vehicles tested were ORVR-equipped. RSA indicated that


there were possibly 3 or 4 ORVR-equipped vehicles tested during the test program.


Notes on Specific Emissions Factors:


The vehicle fueling EF may be typical of other GDF with balance Stage II VRS, with similar RVP,


(percent ORVR is not known).


The UST vent and fugitive EF may be typical of other GDFs with balance Stage II VRS, with P/V valve,


with similar RVP (percent ORVR is not known).


The spillage EF may be typical of other GDF with similar nozzles.


31
Source Company/Organization: 

OPW MO/PETP Testing Final Report, Mobil Mart, St. Louis, Missouri, May 1998 through 

December 1998. Prepared by Environmental Solutions, Inc., for the Missouri Department 

of Natural Resources (MDNR). [Submitted by RSA] 

Test Scenario: 

The Mobil Mart uses a balance Stage II VRS with P/V valves on the UST vents. There are 4 

USTS all manifolded together. A total of 205 vehicles were tested; 5 of these were ORVR 

vehicles, and this percentage is representative of the actual fleet (2.4%). 

Emission Testing: 

The following MO/PETP tests were conducted: 

•	 Bench Testing (MO/TP-201.2B) - requires bench testing of nozzles, P/V valves, 

drain valves for transition flow, and leak rates 

• Dynamic Pressure (Back Pressure) Testing (MO/TP-201.4) 

• Static Pressure (Leak Decay) Testing (MO/TP-201.3) 

• Stage I Efficiency Test (MO/TP-201.1) 

• Stage II Efficiency Test (MO/TP-201.2) 

• Spillage and Pseudo-Spillage (MO/TP-201.2C) 

Operating Data: 

Continuous T and P data were taken for a 180-day period as part of the testing; these data include 

T and P of the UST, ambient temperatures, barometric pressure but were not provided as part of 

the report. 

Results and Conclusions Reported: 

Test results are shown in the table below: 

32
Summary of Stage I and Stage II Test Results 

Source Uncontrolled System 

(without VRS) 

lbs/1,000 gal 

Balance VRS 

lbs/1,000 gal 

Efficiency Relative 

to Uncontrolled 

System 

Loading (Stage I) 16.5 

[AP-42 E F equation] 

0.0 

[measured] 

100% 

Vehicle Fueling 14.6 

[AP-42 E F equation] 

0.79 

[emissions 

mea surem ent] 

94.6% 

Spillage/Pseudo-Spillage 0.46 0.02 

[measured] 

97.8% 

Breathing (Pressure 

Related Fugitives from 

com pon ents such as P /V 

valves and no zzles) 

1.00 

[CARB EF] 

0.06 

[measured] 

94.0% 

TOTAL 32.6 0.87 97.3% 

Comments: 

Notes on Specific Emissions Factors:


The vehicle fueling EF may be typical of other GDF with balance Stage II VRS, with similar


RVP, percent ORVR.


The UST vent and fugitive EF may be typical of other GDFs with balance Stage II VRS, with


P/V valve, with similar RVP, percent ORVR.


The spillage EF may be typical of other GDF with similar nozzles.


As an additional analysis, RSA went back to the original test data and considered the impact of 

ORVR on Stage II balance systems. RSA noticed a reduction in the average emissions factor 

when both ORVR and Stage II balance systems were used at the same time. It is not clear 

whether the emissions factor given is for vehicle refueling only or represents an overall average 

emissions factor. The table below shows the data. 

1998 1998 

Impact of ORVR on a Stage I

M odel Year 

I Balance VRS 

1999 

ORV R-equipped No Yes Yes 

Number of ORVR -equipped Vehicles 11 5 6 

Average Emissions Factor, lb/1,000 gal 0.302 0.050 0.042 

Std Deviation of Emissions Factor 0.621 0.045 0.046 

Ave rage V apo r Rec overy Efficien cy, % 98.1 99.7 99.7 

Std D eviation of V apo r Rec overy Efficien cy, % 3.99 0.29 0.29 

33
Source Company/Organization (include Title and date): 

DaimlerChrysler Corporation St. Louis Assembly Plant - South, MOPETP Testing Final 

Report, January 2001 through February 2002. Remote Sensing Air, Inc. for Missouri 

Department of Natural Resources. May 28, 2004. [Sent by RSA] 

MO/PETP Testing Report for DaimlerChrysler Corporation St. Louis Assembly Plant -

South, Final Report. URS Corporation for Daimler Chrysler Corporation. January 30, 

2003. [Sent by AAM] 

Addendum to the MO/PETP Testing Report for DaimlerChrysler Corporation St. Louis 

Assembly Plant - South, Final Report, for the Single Canister On-Board Refueling Vapor 

Recovery System MO-PETP Testing Conducted on February 8, 2003. URS Corporation 

for Daimler Chrysler Corporation. October 16, 2003. [Sent by AAM] 

Approval Letter 2004-03 for DaimlerChrysler St. Louis South Assembly Plant. From 

R. Randolph, MDNR, to T. Tecklenburg, DaimlerChrysler Corporation. [Sent by AAM] 

Test Scenario (Describe): 

All vehicles from the production area are ORVR, i.e., fuel 100 percent ORVR vehicles. The 

GDF has a different configuration than traditional. There are two fueling areas, with no return of 

vapors from the assembly line fueling area to the UST, i.e., no Stage II VRS, and a satellite 

fueling area, with a balance vapor recovery nozzle that returns vapors to the UST. Fueling at the 

satellite fueling area is restricted to ORVR vehicles and fueling on weekends is to be limited. 

The satellite fueling area has a throughput of approximately 1.4 percent, i.e., minimal impact. 

There are three 20,000 gal USTs located in a tank farm. Gasoline is chilled prior to fueling. The 

three vent pipes from the USTs are [vapor] manifolded to one vent with a P/V valve. For fueling 

emissions testing, emissions were collected using a sleeve around the nozzle interface to collect 

emissions escaping from this area; the emissions from the ORVR canister vent were collected in 

a second sleeve. (The plant had a Hasstech processor/incinerator as the main vapor recovery 

control prior to production of all ORVR vehicles but MDNR has since allowed the facility to 

remove it; the Hasstech incinerator controlled vehicle fueling emissions.) The State agency 

allowed the facility to remove Stage II VRS for MY2001, i.e., in 2000. Some emissions 

information is based on calculations. 

Emissions Testing Data: 

The following MO/PETP tests were conducted: 

•	 Bench Testing (Modified MO/TP-201.2B) - requires bench testing of nozzles, P/V 

valves, drain valves for transition flow, and leak rates 

• Static Pressure (Leak Decay) Testing (MO/TP-201.3) 

• Stage I Efficiency Test (MO/TP-201.1) 

• Continuous monitoring of storage tanks 

•	 Stage II Efficiency Test (Modified MO/TP-201.2), both dual and single canister 

ORVR testing 

• Spillage and Pseudo-Spillage (MO/TP-201.2C) 

34
Operating Data: 

Continuous T and P data of the USTs are available for September 9 through December 20, 2001, 

for a total of 103 days. Data are available for 146,302 minutes out of 148,320 possible minutes, 

or 98.6 percent of the time period. The data available for all 103 days are shown in an attached 

table along with the daily average pressures and the minimum and maximum 1-min P value for 

each day. Pressures for a typical weekday are shown in an attached graph for Wednesday 

October 17; pressures for a typical weekend day, when the facility is closed for 2 days, are shown 

in an attached graph for Sunday October 21. The weekday graph shows increasing pressures 

(due to vapor growth) overnight and negative pressures during the day while fueling operations 

are occurring. The average P for the weekday was -3.09 in. w.c. (minimum 1-min P of -7.69 and 

maximum 1-min P of +1.67 in. w.c.). The weekend day graph shows continued vapor growth 

and positive pressure for the entire day; the average P for the day was +2.45 in. w.c. (minimum 

1-min P of +1.68 and maximum 1-min P of +2.99 in. w.c.). 

Frequency plot of all P data. A graph showing the frequency of pressure for the 103 day period is 

also provided. The pressure is greater than 0 in. w.c. for 43,265 minutes, or 29.6 percent of the 

time; pressure related fugitive emissions are likely to be occurring during these time periods. 

The pressure is greater than 3 in. w.c for 6,249 minutes, or 4.2 percent of the time period; UST 

vent emissions are likely occurring during these period when the P/V valve opens. Because the 

facility fixed a leak on November 19, the frequency plots are shown for the time period before 

and after the leak. 

Frequency plot for P data before and after a leak is fixed. September 9 through November 19. A 

frequency plot for the time period before the leak was fixed, from September 9 through 

November 19, is provided. A frequency plot for the period after the leak was fixed, November 

20 through December 20, is also provided. The “before” time periods show that the UST 

remains at the most negative pressures for approximately half of that following the leak fix (19 

percent vs. 48 percent), i.e., with the leak fix, the tank can maintain negative pressures better. In 

addition, the UST in general will maintain positive pressures for longer periods (4.72 percent) 

than before the leak fix (4.08 percent); UST vent and fugitive emissions occur during positive 

pressure periods. For a vapor tight UST, the positive pressures are maintained and UST 

emissions occur from the UST vent. For a leaking UST, positive pressures are not maintained as 

long because fugitive leaks are occurring. 

The total pressure related fugitive and UST vent emissions were calculated to be 281.3 lb over 

the 103 day time period; with a fuel throughput of 885,450 gal, the emissions factor for UST 

fugitives and vent emissions is 0.32 lb/1,000 gal. [This value is slightly higher than the value 

reported by the facility in the test report, however, no explanation as to why is given.] 

35
Analysis of Frequency Plots for UST Pressure for All Data and Before and After the Fixing 

Leak 

Pressure 

ranges, in. 

w.c. 

All data Before leak is fixed After leak is fixed 

minutes % minutes % minutes % 

< -8.0 40,809 27.9% 19,680 19.2% 21,129 48.3% 

-8.0 < P < 0.0 62,137 42.5% 50,166 48.9% 11,971 27.4% 

<0.0 102,946 70.4% 69,846 68.1% 33,100 75.7% 

>0.0 43,265 29.6% 32,651 31.9% 10,614 24.3% 

>3.5 6,249 4.27% 4,184 4.08% 2,065 4.72% 

Results and Conclusions Reported: 

Summary of Emissions Factors and Efficiency Determinations for both Stage I and Stage II 

(single canister ORVR). [This is the type or canister currently used; single canister is used 

on MY2003 and later.] 

Source Uncontrolled System 

[in MY2001/2002 mockup tanks] 

lbs/1,000 gal 

Loading (Stage I) 13.5 

[AP-42 E F eqn] 

Vehicle Fueling 17.56 

[emissions m easureme nt] 

Spillage/Pseudo-Spillage 0.75 

[CARB EF] 

Breathing (Pressure 

Related F ugitives) 

- UST em 

- fugitives 

1.0 

[modified AP-42 EF] 

TOTAL 32.87 

Controlled MY2003 ­

mockup, 

lbs/1,000 gal 

Efficiency Relative to 

Uncontrolled System 

0.13 

[measured] 

0.0779 

[emissions 

mea surem ent] 

0.48 

[measured] 

0.24 

[calculated based on 

P, T, time] 

0.93 

99.0% 

99.6% 

36.0% 

76.0% 

97.2% 

Uncontrolled: No chilling, no ORVR, no Stage II VRS, w/ P/V valve [some vapor return from satellite fueling


balance nozzle, but small impact because less gasoline throughput].


Controlled: w/ Chilling, w/ORVR single, No Stage II VRS, w/ P/V valve.


[The controlled breathing emissions estimated from the data are 0.32 lb/1,000 gal, which does the value shown here


as provided by the facility in the test report.] 

36
Summary of Emissions Factors and Efficiency Determinations for Stage II alone (single canister 

ORVR). 

Source 

Vehicle Fueling 

Spillage/Pseudo-Spillage 

Breathing (Pressure Related 

Fugitives) 

- UST em 

- fugitives 

TOTAL 

Uncontrolled System 

[in MY2001/2002 mockup tanks] 

lbs/1,000 gal 

17.56 

[emissions m easureme nt] 

0.75 

[CARB EF] 

1.0 

[modified AP-42 EF] 

19.31 

Controlled MY2003 

- mockup, 

lbs/1,000 gal 

0.0779 

[emissions 

mea surem ent] 

0.48 

[measured] 

0.24 

[calculated based 

on P, T, time] 

0.7979 

Uncontrolled: No chilling, no ORVR, no Stage II VRS, w/ P/V valve [some vapor return from satellite fueling


balance nozzle, but small impact because less gasoline throughput].


Controlled: w/ Chilling, w/ORVR single, No Stage II VRS.


[The controlled breathing emissions estimated from the data are 0.32 lb/1,000 gal, which does the value shown here


as provided by the facility in the test report.] 

Summary of Emissions Factors and Efficiency Determinations for both Stage I and Stage II (dual 

Efficiency Relative to 

Uncontrolled System 

99.6% 

36.0% 

76.0% 

95.87% 

canister ORVR). [Dual canisters are no longer in use after MY2002.] 

Source 

Loading (Stage I) 

Vehicle Fueling 

Spillage/Pseudo-Spillage 

Breathing (Pressure Related 

Fugitives) 

- UST em 

- fugitives 

TOTAL 

Uncontrolled System 

[MY2001/2002 mockup tanks] 

lbs/1,000 gal 

13.5 

[AP-42 eqn 3-1] 

17.56 

[emissions m easureme nt] 

0.75 

[CARB EF] 

1.0 

[modified AP-42 eqn] 

32.87 

Controlled 

MY2001/2002, 

lbs/1,000 gal 

0.13 

0.014 

[emissions 

mea surem ent] 

0.48 

[measured] 

0.24 

[calc based on P, T, 

time] 

0.86 

Efficiency Relative to 

Uncontrolled System 

99.0% 

99.9% 

36.0% 

76.0% 

97.4% 

Uncontrolled: No chilling, no ORVR, no Stage II VRS, w/ P/V valve [some vapor return from satellite fueling


balance nozzle, but small impact because less gasoline throughput].


Controlled: w/ Chilling, No Stage II VRS, w/ORVR dual.


[The controlled breathing emissions estimated from the data are 0.32 lb/1,000 gal, which does the value shown here


as provided by the facility in the test report.] 

37
Summary of Emissions Factors and Efficiency Determinations for Stage II alone (dual canister 

ORVR). 

Source Uncontrolled System 

[in MY2001/2002 mockup tanks] 

lbs/1,000 gal 

Controlled 

MY2001/2002, 

lbs/1,000 gal 

Efficiency Relative to 

Uncontrolled System 

Vehicle Fueling 17.56 

[emissions m easurement] 

0.014 

[emissions 

mea surem ent] 

99.9% 

Spillage/Pseudo-Spillage 0.75 

[CARB EF] 

0.48 

[measured] 

36.0% 

Breathing (Pressure Related 

Fugitives) 

- UST em 

- fugitives 

1.0 

[modified AP-42 eq n] 

0.24 

[calc based on P, 

T, time] 

76.0% 

TOTAL 19.31 0.734 96.2% 

Uncontrolled: No chilling, no ORVR, no Stage II VRS, w/ P/V valve [some vapor return from satellite fueling


balance nozzle, but small impact because low gasoline throughput].


Controlled: w/ Chilling, No Stage II VRS, w/ORVR dual.


Comments: 


Because the leak decay test is conducted during off-production hours when there is continual


pressurizing of the tank with vapor growth, the growth may mask a leak greater than the allowed


amount. MO DNER recommended that it might be more productive to require continuous


monitoring for one month every 5 years rather than the leak decay test.


The operating data for the UST pressures show that the system is at positive pressure (i.e., greater


than 0.0 in. w.c.) for 720 hours out of the 103 day period, or 29 percent of the time. Because


gasoline dispensing stops for longer periods over weekends in addition to overnight periods,


these USTs likely operate at positive pressure for a higher percentage of time than would likely


be seen at traditional uncontrolled GDF. These periods at pressures greater than 0.0 in. w.c. are


when UST fugitive and vent emissions occur.


Chilling of the gasoline suppresses vaporization and therefore emissions, so vehicle fueling


emissions are lower than they would be otherwise at ambient conditions. Chilling of gasoline is


a unique operating condition that is used at several, but not all, facilities nationwide; chilling may


not be representative of automobile manufacturers nationwide.


The green tank effect, i.e., no gasoline vapors present prior to fueling, may affect the vehicle


fueling emissions, likely affects the refueling emissions levels. AAM has indicated that refueling


emissions would be lower with the green tank effect, however, one State agency indicated that


the emissions may be higher, particularly for the immediate splash into the vehicle tank, then the


emissions would be similar to refueling emissions for the remainder of the fueling event. At any


rate, these data may not be representative of traditional refueling at GDF.


38
The emissions levels from the UST tank are essentially similar to an uncontrolled UST (i.e, no


Stage II VRS) with a P/V valve and may be representative of traditional refueling at GDF, with


one noted difference. One difference in the UST emissions would be that the facility typically


fuels on Monday through Friday and shut downs over the weekend (i.e., no fueling operations for


a 2-day period), causing an extended vapor growth period and more UST fugitive and vent


emissions. A traditional GDF would be open 7 days per week without an extended shut down or


vapor growth period. The emissions levels for UST emissions shown in this report may actually


be higher than UST emissions from a traditional GDF.


Notes on Specific Emissions Factors:


Uncontrolled vehicle fueling EFs with ambient T fuel may be affected by the green tank effect.


Vehicle fueling EFs with ORVR-control with ambient temperature fuel may be affected by the


green tank effect.


Vehicle fueling EFs with ORVR-control and with chilled gasoline may be lower because of the


lower vapor pressure of the gasoline and may be affected by the green tank effect.


Vehicle fueling EFs with chilled gasoline may be lower because of the lower vapor pressure of


the gasoline and may be affected by the green tank effect.


Uncontrolled UST vent and fugitives EF with P/V valve may be similar to other uncontrolled


tanks (i.e., non-Stage II VRS) with one noted difference, increased UST emissions related to the


longer shut down periods of the facility.


39
Daily Average Tank Pressures from September 9 to December 20, 2001 

Date CountOfTP_"WC Percent Complete AvgOfTP_"WC MinOfTP_"WC MaxOfTP_"WC 

9/9/2001 1439 99.93% 1.21 0.033 3.046 

9/10/2001 1440 100.00% -6.42 -9.62 0.375 

9/11/2001 1440 100.00% -2.62 -9.59 3.296 

9/12/2001 1440 100.00% -5.37 -9.69 3.025 

9/13/2001 1440 100.00% -5.91 -9.81 3.785 

9/14/2001 316 21.94% -2.06 -7.69 2.69 

9/15/2001 1440 100.00% -5.03 -8.98 3.506 

9/16/2001 1440 100.00% 1.09 -7.01 3.104 

9/17/2001 1440 100.00% -4.10 -9.49 3.171 

9/18/2001 1440 100.00% -5.34 -9.44 3.83 

9/19/2001 1440 100.00% -6.66 -9.25 1.19 

9/20/2001 1440 100.00% -6.59 -9.65 0.939 

9/21/2001 1440 100.00% -4.60 -9.2 0.874 

9/22/2001 1440 100.00% -3.02 -9.26 2.909 

9/23/2001 1440 100.00% 2.27 0.428 3.199 

9/24/2001 1440 100.00% -5.08 -9.59 0.424 

9/25/2001 1440 100.00% -5.75 -9.57 3.7 

9/26/2001 1440 100.00% -5.33 -9.91 4.451 

9/27/2001 1440 100.00% -4.58 -9.59 2.578 

9/28/2001 1440 100.00% -5.79 -9.52 0.968 

9/29/2001 1440 100.00% 1.44 -6.571 3.115 

9/30/2001 1440 100.00% -0.57 -9.77 2.98 

10/1/2001 1440 100.00% -4.10 -8.67 0.727 

10/2/2001 1439 99.93% -5.91 -9.43 0.229 

10/3/2001 1440 100.00% -3.75 -9.42 1.61 

10/4/2001 1440 100.00% -4.00 -8.97 0.433 

10/5/2001 1440 100.00% -4.03 -9.05 1.44 

10/6/2001 1440 100.00% 1.95 -5.371 3.29 

10/7/2001 1440 100.00% 2.83 2.491 3.141 

10/8/2001 1440 100.00% -0.43 -8.77 2.813 

10/9/2001 1440 100.00% -3.09 -8.03 1.205 

10/10/2001 1440 100.00% -2.72 -6.986 2.324 

10/11/2001 1440 100.00% -2.55 -7.23 1.681 

10/12/2001 1440 100.00% -1.99 -4.023 1.561 

10/13/2001 1440 100.00% -5.24 -9.19 2.985 

10/14/2001 1440 100.00% -0.26 -8.83 1.772 

10/15/2001 1440 100.00% -4.23 -9.21 0.497 

10/16/2001 1440 100.00% -3.39 -7.67 2.471 

10/17/2001 1440 100.00% -3.09 -7.69 1.669 

10/18/2001 1440 100.00% -4.03 -9.19 0.453 

10/19/2001 1440 100.00% -4.76 -9.79 3.46 

10/20/2001 1440 100.00% 1.92 -4.306 3.106 

10/21/2001 1440 100.00% 2.45 1.679 2.993 

10/22/2001 1440 100.00% -4.64 -9.65 2.851 

10/23/2001 1440 100.00% -5.02 -9.03 2.332 

10/24/2001 1440 100.00% -4.76 -9.8 1.642 

10/25/2001 1440 100.00% -5.54 -9.99 1.795 

10/26/2001 1440 100.00% -4.35 -9.91 4.733 

10/27/2001 1440 100.00% -1.45 -6.871 3.198 

10/28/2001 1439 99.93% 1.38 -2.688 3.123 

10/29/2001 1440 100.00% -3.62 -9.83 2.911 

10/30/2001 1440 100.00% -4.48 -9.8 3.434 

10/31/2001 1440 100.00% -4.52 -9.66 3.557 

11/1/2001 1440 100.00% -6.30 -10.05 2.944 

11/2/2001 1440 100.00% -7.69 -9.89 0.008 

11/3/2001 1440 100.00% -3.53 -9.48 2.109 

40
Date CountOfTP_"WC Percent Complete AvgOfTP_"WC MinOfTP_"WC MaxOfTP_"WC 

11/4/2001 1440 100.00% 1.89 -2.764 4.815 

11/5/2001 1440 100.00% -4.49 -9.76 3.041 

11/6/2001 1440 100.00% -6.42 -9.78 2.735 

11/7/2001 1440 100.00% -6.50 -9.84 1.469 

11/8/2001 1440 100.00% -7.19 -9.91 1.726 

11/9/2001 1440 100.00% -5.96 -9.68 3.789 

11/10/2001 1440 100.00% 1.00 -8.75 4.117 

11/11/2001 1440 100.00% 2.42 0.864 3.269 

11/12/2001 1440 100.00% -4.27 -9.7 3.091 

11/13/2001 1440 100.00% -6.56 -9.88 4.457 

11/14/2001 1440 100.00% -7.07 -10.06 0.809 

11/15/2001 1440 100.00% -6.75 -10.03 0.649 

11/16/2001 1440 100.00% 0.83 -9.59 3.387 

11/17/2001 1440 100.00% 2.64 2.155 2.918 

11/18/2001 1438 99.86% 2.50 -9.7 3.037 

11/19/2001 1440 100.00% -5.06 -9.84 2.845 

11/20/2001 1440 100.00% -6.43 -9.9 3.504 

11/21/2001 1440 100.00% -5.73 -9.91 18.52 

11/22/2001 1440 100.00% 0.71 -9.94 3.416 

11/23/2001 1440 100.00% 2.74 2.013 3.069 

11/24/2001 1440 100.00% 1.99 0.175 5.802 

11/25/2001 1440 100.00% -1.58 -3.004 0.174 

11/26/2001 1440 100.00% -6.03 -9.81 0.644 

11/27/2001 1440 100.00% -7.62 -9.87 5.501 

11/28/2001 1440 100.00% -7.55 -9.88 3.706 

11/29/2001 1440 100.00% -7.55 -9.85 12.81 

11/30/2001 1440 100.00% -7.95 -9.87 0.979 

12/1/2001 1440 100.00% -7.98 -9.95 4.411 

12/2/2001 1440 100.00% 0.79 -9.79 3.359 

12/3/2001 1440 100.00% -5.61 -9.9 3.033 

12/4/2001 1440 100.00% -7.86 -10.01 -0.486 

12/5/2001 1440 100.00% -7.91 -10 0.007 

12/6/2001 1440 100.00% -7.89 -9.94 1.46 

12/7/2001 1440 100.00% -8.17 -9.97 -0.538 

12/8/2001 1440 100.00% -6.65 -9.9 1.207 

12/9/2001 1440 100.00% -1.27 -9.37 3.225 

12/10/2001 1440 100.00% -5.59 -9.95 3.033 

12/11/2001 1440 100.00% -7.82 -9.99 0.071 

12/12/2001 1440 100.00% -8.45 -9.98 -2.843 

12/13/2001 1440 100.00% -8.30 -9.96 -3.341 

12/14/2001 551 38.26% -7.29 -9.96 1.042 

12/15/2001 1440 100.00% 1.27 -9.85 3.268 

12/16/2001 1440 100.00% 2.92 1.843 3.099 

12/17/2001 1440 100.00% -5.53 -9.93 3.097 

12/18/2001 1440 100.00% -8.14 -9.96 -2.528 

12/19/2001 1440 100.00% -8.01 -9.99 -0.316 

12/20/2001 1440 100.00% -6.71 -10.01 3.989 

103 days total during time period 

148,320 146,302 minutes available data 98.64% 

total minutes 

during time period 

2,472 2,438 hours available data 98.64% 

total hours during 

the time period 

41
Wednesday October 17, 2001

-10

-2-4-6-8

420

0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00

Time (CST)

 (IN_H2O) AVG.E MINUT SSUREERP

6560555045403530

) FG (DE AVG.E MINUT URE RATE MPET

TP_"WC TT_degF

Daimler Chrysler MOPETP

42
Sunday October 21, 2001

-10.0

-2.0-4.0-6.0-8.0

4.02.00.0

0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00

Time (CST)

O) H2 (IN_ URE MINUTE AVG.S PRES

706560555045403530

 (DEG F) TEMPERATURE MINUTE AVG.

TP_"WC TT_degF

Daimler Chrysler MOPETP

43
Frequency of 1-Minute P readings 

September 9 through December 20, 2001 (103 days) 

0 

8000 7000 6000 5000 4000 3000 2000 1000 

1- 0.00 9- 0. 0 8- 0. 0 7- 0. 0 6- 0. 0 5- 0. 0 4- 0. 0 3- 0. 0 2- 0. 0 1- 0. 0 0 0. 0 1 0. 0 2 0. 0 3 0. 0 4 0. 0 5 0. 0 

Minute P readings, in. w.c. 

Frequency minute P readings freq 

These data are for an uncontrolled UST with no vapor returned to the tank; there is a P/V valve on the UST vent. A total of 10 minutes with pressure greater than +5.5 in. w.c. occurred over the 103 day period and are not shown in this graph. 

44
Sunday October 21, 2001

-10.0

-2.0-4.0-6.0-8.0

4.02.00.0

0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00

Time (CST)

O) H2 (IN_ URE MINUTE AVG.S PRES

706560555045403530

 (DEG F) TEMPERATURE MINUTE AVG.

TP_"WC TT_degF

Daimler Chrysler MOPETP

45
Frequency of 1-Minute P readings 

September 9 through December 20, 2001 (103 days) 

0 

8000 7000 6000 5000 4000 3000 2000 1000 

1- 0.00 9- 0. 0 8- 0. 0 7- 0. 0 6- 0. 0 5- 0. 0 4- 0. 0 3- 0. 0 2- 0. 0 1- 0. 0 0 0. 0 1 0. 0 2 0. 0 3 0. 0 4 0. 0 5 0. 0 

Minute P readings, in. w.c. 

Frequency minute P readings freq 

These data are for an uncontrolled UST with no vapor returned to the tank; there is a P/V valve on the UST vent. A total of 10 minutes with pressure greater than +5.5 in. w.c. occurred over the 103 day period and are not shown in this graph. 

46
Frequency of 1-Minute P readings 

September 9 through November 19, 2001 (72 days) 

0 

500 

4000 3500 3000 2500 2000 1500 1000 

1- 0.00 9- 0. 0 8- 0. 0 7- 0. 0 6- 0. 0 5- 0. 0 4- 0. 0 3- 0. 0 2- 0. 0 1- 0. 0 0 0. 0 1 0. 0 2 0. 0 3 0. 0 4 0. 0 5 0. 0 

Minute P readings, in. w.c. 

Frequency minute P readings freq 

These data are for an uncontrolled UST with no vapor returned to the tank; there is a P/V valve on the UST vent. There was leak occurring during this time period. 

47
Frequency of 1-Minute P readings 

September 9 through November 19, 2001 (72 days) 

0 

500 

4000 3500 3000 2500 2000 1500 1000 

1- 0.00 9- 0. 0 8- 0. 0 7- 0. 0 6- 0. 0 5- 0. 0 4- 0. 0 3- 0. 0 2- 0. 0 1- 0. 0 0 0. 0 1 0. 0 2 0. 0 3 0. 0 4 0. 0 5 0. 0 

Minute P readings, in. w.c. 

Frequency minute P readings freq 

These data are for an uncontrolled UST with no vapor returned to the tank; there is a P/V valve on the UST vent. There was leak occurring during this time period. 

48
Frequency of 1-Minute P readings 

November 20 through December 20, 2001 (31 days) 

0 

500 

4000 3500 3000 2500 2000 1500 1000 

1- 0.00 9- 0. 0 8- 0. 0 7- 0. 0 6- 0. 0 5- 0. 0 4- 0. 0 3- 0. 0 2- 0. 0 1- 0. 0 0 0. 0 1 0. 0 2 0. 0 3 0. 0 4 0. 0 5 0. 0 

Minute P readings, in. w.c. 

Frequency minute P readings freq 

These data are for an uncontrolled UST with no vapor returned to the tank; there is a P/V valve on the UST vent. These data are for after a leak was fixed. A total of 10 minutes with P > +5.5 in. w.c. occurred over the 31 day period and are not shown. 

49
Calculation of Pressure-Related Fugitives for September 9 through December 20, 2001 

SumOfLBS HC SumOfGallons Dropped Expr1 

281.26 885,450 0.3176 lb/1,000 gal 

TP1 TP2 SumOfMinutes AvgOfLPM VolL LBS HC 

0.25 0.75 5,087 0.02 76.31 0.27 

0.75 1.25 2,395 0.04 95.80 0.34 

1.25 1.75 2,574 0.06 144.79 0.52 

1.75 2.25 2,835 0.15 418.95 1.51 

2.25 2.75 7,639 0.40 3,074.70 11.06 

2.75 3.25 18,675 2.00 37,277.38 134.06 

3.25 3.75 273 4.35 1,186.71 4.27 

3.75 4.25 47 44.45 2,089.09 7.51 

4.25 4.75 26 64.33 1,672.49 6.01 

4.75 5.25 5 104.08 520.41 1.87 

5.25 5.75 4 143.84 575.36 2.07 

5.75 6.25 1 183.60 183.60 0.66 

6.25 6.75 2 223.35 446.70 1.61 

6.75 7.25 1 263.11 263.11 0.95 

7.25 7.75 1 302.86 302.86 1.09 

7.75 8.25 1 342.62 342.62 1.23 

8.25 8.75 1 382.38 382.38 1.38 

8.75 9.25 1 422.13 422.13 1.52 

9.25 9.75 0 461.89 0.00 0.00 

9.75 10.25 3 501.64 1,504.93 5.41 

10.25 10.75 0 541.40 0.00 0.00 

10.75 11.25 0 581.16 0.00 0.00 

11.25 11.75 0 620.91 0.00 0.00 

11.75 12.25 2 660.67 1,321.34 4.75 

12.25 12.75 2 700.43 1,400.85 5.04 

12.75 13.25 1 740.18 740.18 2.66 

13.25 13.75 2 779.94 1,559.88 5.61 

13.75 14.25 1 819.69 819.69 2.95 

14.25 14.75 0 859.45 0.00 0.00 

14.75 15.25 4 899.21 3,596.83 12.93 

15.25 15.75 2 938.96 1,877.93 6.75 

15.75 16.25 3 978.72 2,936.16 10.56 

16.25 16.75 5 1018.48 5,092.38 18.31 

16.75 17.25 2 1058.23 2,116.46 7.61 

17.25 17.75 1 1097.99 1,097.99 3.95 

17.75 18.25 1 1137.74 1,137.74 4.09 

18.25 18.75 3 1177.50 3,532.50 12.70 

18.75 19.25 0 1217.26 0.00 0.00 

19.25 19.75 0 1257.01 0.00 0.00 

19.75 20.25 0 1296.77 0.00 0.00 

20.25 20.75 0 1336.52 0.00 0.00 

20.75 21.25 0 1376.28 0.00 0.00 

21.25 21.75 0 1416.04 0.00 0.00 

21.75 22.25 0 1455.79 0.00 0.00 

22.25 22.75 0 1495.55 0.00 0.00 

>0.25 in. w.c. 39,600 minutes 281.26 lbs HC 

p-related fug em and UST 27.50 days

660 hours 

>3 in. w.c. 19,070 minutes 

13.24 days 

318 hours 

UST vent P/V valve em 

50
Data Source Company/Organization (include Title and date): 

MO/PETP Testing Report for Ford Motor Company St. Louis Assembly Plant, Hazelwood, 

Missouri. URS Corporation. August 27, 2003. [Sent by AAM] 

Approval Letter 2004-01 for Ford Motor Assembly Plant. From L. Mosby, MDNR, to 

M. Szafranski, Ford Motor Company. [Sent by AAM] 

Ford Hazelwood MOPETP Testing Final Report, Ford Motor Company, St. Louis 

Assembly Plant (SLAP), Hazelwood, Missouri. July 2002 through March 2003. Remote 

Sensing Air, Inc., for Missouri Department of Natural Resources (DNR). [Sent by RSA] 

Test Scenario (Describe): 

All vehicles fueled at the facility are 100 percent ORVR vehicles. No Stage II controls (no return 

of vapors to the UST) are used. No UST vent control devices are used (i.e., no vapor processor). 

There is one 30,000-gal UST tank, with 2 UST vents; one of these UST vents was permanently 

capped off, and the other UST vent has a P/V valve. All models have the same fuel tank, fill 

port, and ORVR canister configuration for a given model year. MY2003 vehicles were in 

production at the time of the test, and all were dual canister systems for ORVR. [In MY2004 and 

later model years, a single canister was used.] Both types of canisters were tested: MY2003 as 

fully produced vehicles and MY2004 as mockups. Emissions were collected with a sleeve 

around the nozzle interface. Emissions at the outlet of the ORVR canister were routed to the area 

of the nozzle fillport, so both sources of emissions are measured. The only vehicle fueling 

emissions are at the nozzle/fillport interface. Prior to testing, MDNR had approved 

disconnection of the Stage II vapor recovery control system because all vehicles are ORVR. 

Gasoline is chilled to approximately 43°F prior to fueling. A special nozzle prevents spillage by 

via purge-puff. For MY2003, unchilled gasoline fueling was performed without ORVR; these 

emissions will match up to the MY2004 emissions tests as well because the vehicle fuel tanks are 

identical. Some emissions information is based on calculations. 

Emissions Testing Data: 

The following MO/PETP tests were conducted: 

•	 Bench Testing (Modified MO/TP-201.2B) - requires bench testing of nozzles, P/V 

valves, drain valves for transition flow, and leak rates 

• Static Pressure (Leak Decay) Testing (Modified MO/TP-201.3B) 

• Stage I Efficiency Test (MO/TP-201.1) 

• Stage II Efficiency Test (Modified MO/TP-201.2) 

• Spillage and Pseudo-Spillage (MO/TP-201.2C) 

• Final V/L Testing 

Operating Data: 

Some typical operating data are available in the final test report. Continuous T and P data for 5 

months were recorded as part of the system testing; the facility provided example data for 11 of 

these days, November 8 through November 18, 2002. The data available for all 11 days are 

51
shown in the table below with the daily average pressure and the minimum and maximum 1-min 

P value for each day; data are provided for both the north end and the south end of the UST 

(pressure is monitored at two locations within the tank). In general, the pressure pattern shows 

high vacuum during production operations on weekdays (i.e., during fueling) and high pressures 

at the cracking P of the P/V valves during off times, i.e., overnight and over weekends. The 

weekday graphs show increasing pressures (due to vapor growth) overnight and negative 

pressures during the day while fueling operations are occurring. On Friday November 8, the 

average pressure for the day for the north end of the UST was -6.10 in. w.c. (minimum 1-min P 

of -9.29 in. w.c. and maximum 1-min P of +3.38 in. w.c.). The weekend day graphs show 

continued vapor growth and positive pressure for the entire day. On Sunday November 10, the 

average pressure for the day at the north end of the UST was 2.58 in. w.c. (minimum 1-min P of 

1.26 in. w.c. and maximum 1-min P of +3.32 in. w.c.) 

There are several weekdays with pressure spikes in mid-afternoon when ostensibly the facility 

would be operating and fueling vehicles; it is not clear what event these pressure spikes 

represent. [These data plots were provided in hardcopy and not in color; it was difficult to 

decipher which line represented which data. We made assumptions regarding which lines were 

tank P.] 

Summary of Weekday and Weekend UST Vent Pressures 

Pressure, 

in. w.c. 

Friday, 

11/08 

Saturday, 

11/09 

Sunday, 

11/10 

M onday, 

11/11 

Tuesday, 

11/12 

Wednesday, 

11/13 

Thursday, 

11/14 

N S N S N S N S N S N S N S 

Minimum -9.29 -10.62 -9.12 -10.48 1.26 1.19 -9.16 -10.72 -9.25 -10.65 -9.23 -10.58 NA NA 

Maximum 3.37 3.30 3.40 3.35 3.32 3.22 3.36 3.34 3.39 3.38 3.63 3.58 3.59 3.51 

Average -6.10 -6.87 1.80 1.62 2.58 2.49 -5.27 -5.90 -6.59 -7.33 -5.81 -6.43 -15.44 -11.17 

Pressure, 

psi 

Friday, 

11/15 

Saturday, 

11/16 

Sunday, 

11/17 

M onday, 

11/18 

N S N S N S N S 

Minimum -9.06 -10.47 1.60 1.52 2.27 2.26 -9.29 -10.77 

Maximum 3.38 3.35 3.12 3.06 3.04 3.03 3.06 3.03 

Average 1.58 1.44 2.64 2.59 2.79 2.76 -5.08 -5.77 

Note: Data are provided for pressure gauges at both the north (N) and south (S) ends of the UST. 

52
Results and Conclusions Reported:


Summary of Emissions Factors and Efficiency Determinations for both Stage I and


Efficiency 

Relative to 

Uncontrolled 

System 

MY2004 

mockup tanks, 

single canister, 

lb/1,000 gal 

Efficiency 

Relative to 

Uncontrolled 

System 

100% same same 

99.9% 0.0033 

[emissions 

mea surem ent] 

greater than 

99.9% 

91.6% same same 

87.2% same same 

98.8% 0.333 98.9% 

Uncontrolled: No chilling of gasoline, no ORVR, no Stage II VRS, and with P/V valve. 

Stage II. 

Source 

Loading (Stage I) 

Vehicle Fueling 

Spillage/PseudoSpillage 

Breathing (Pressure 

Related F ugitives) 

- UST em 

- fugitives 

TOTAL 

Uncontrolled 

System 

MY2003 mockup 

tanks, dual canister 

lb/1,000 gal 

13.5 

[AP-42 E F eqn] 

13.5 

[emissions 

measurement] 

0.75 

[CARB EF] 

2.09 

[modified AP-42 

EF] 

29.9 

MY 2003 

assembly line, 

dual canister 

lb/1,000 gal 

0.0 

[measured] 

0.0118 

[emissions 

measurement] 

0.063 

[measured] 

0.267 

[calculation 

based on P, T, 

time] 

0.342 

Controlled: Chilling of gasoline, with ORVR, no Stage II VRS, with P/Vvalve, and with purge puff nozzle. 

Summary of Emissions Factors and Efficiency Determinations for Stage II alone. 

Source 

Vehicle Fueling 

Spillage/PseudoSpillage 

Breathing (Pressure 

Related F ugitives) 

- UST em 

- fugitives 

TOTAL 

Uncontrolled


System


MY2003 mockup


tanks, dual canister,


lb/1,000 gal


13.5 

[emissions 

mea surem ent] 

0.75 

[CARB EF] 

2.09 

[modified AP-42 

EF] 

16.3 

MY 2003 

assembly line, 

dual canister, 

lb/1,000 gal 

0.0118 

[emissions 

mea surem ent] 

0.063 

[measured] 

0.267 

[calculation 

based on P, T, 

time] 

0.342 

Efficiency MY2004 

Relative to in mockup 

Uncontrolled tanks, single 

System canister, 

lb/1,000 gal 

99.9% 0.0033 

[emissions 

mea surem ent] 

greater than 

99.9% 

91.6% same same 

87.2% same same 

97.9% 

Efficiency 

Relative to 

Uncontrolled 

System 

0.333 98.0% 

Uncontrolled: No chilling of gasoline, no ORVR, no Stage II VRS, w/ P/V valve.


Controlled: Chilling of gasoline, with ORVR, no Stage II VRS, with P/V valve, and with purge puff nozzle.


53
In addition to the testing shown in the tables above, an additional analysis of the mockup testing 

for MY2003 showed controlled vehicle fueling emissions levels of 0.1965 lb/1000 gal, which is a 

control efficiency of 98.5 percent. These data are representative of ambient temperature fuel, no 

Stage II VRS, and dual canister ORVR. 

Comments: 

Breathing emissions from the UST vent are unrelated to throughput.


At automobile manufacturing facilities, the gasoline dispensing stops for longer periods over


weekends in addition to overnight periods. The UST at automobile manufacturing facilities


likely operate at positive pressure for a higher percentage of time than would be likely at a


traditional uncontrolled GDF. These periods at pressures greater than 0.0 in. w.c. are when UST


fugitive and vent emissions occur.


Chilling of gasoline suppresses vaporization and therefore emissions, so vehicle fueling


emissions are lower than they would be otherwise at ambient conditions. Chilling of gasoline is


a unique operating condition that is used at several, but not all, facilities nationwide; chilling may


not be representative of automobile manufacturers nationwide.


The green tank effect, i.e., no gasoline vapors present prior to fueling, may affect the vehicle


fueling emissions. AAM has indicated that refueling emissions would be lower with the green


tank effect because no vapors are present to be displaced, however, one State agency has


indicated that the emissions may be higher, particularly for the immediate splash into the vehicle


tanks, then the emissions would be similar to refueling emissions for the remainder of the fueling


event. At any rate, the green tank effect is a universal condition for all automobile


manufacturers, and these data may not be representative of traditional refueling at GDF.


The emissions levels from the UST tank are essentially similar to an uncontrolled UST (i.e, no


Stage II VRS) with a P/V valve and may be representative of traditional refueling at GDF, with


one noted difference. One difference in the UST emissions would be that the facility typically


fuels on Monday through Friday and shut downs over the weekend (i.e., no fueling operations for


a 2-day period), causing an extended vapor growth period and more UST fugitive and vent


emissions. A traditional GDF would be open 7 days per week without an extended shut down or


vapor growth period. The levels for UST emissions shown in this report may actually be higher


than UST emissions from a traditional GDF.


Notes on Specific Emissions Factors:


Uncontrolled vehicle fueling EFs with ambient T fuel may affected by the green tank effect.


Vehicle fueling EFs with ORVR-control with ambient temperature fuel may be affected by the


green tank effect.


Vehicle fueling EFs with ORVR-control and with chilled gasoline may be lower because of the


lower vapor pressure of the gasoline and may be affected by the green tank effect.


Vehicle fueling EFs with chilled gasoline may be lower because of the lower vapor pressure of


the gasoline and may be affected by the green tank effect.


Uncontrolled UST vent and fugitives EF with P/V valve may be similar to other uncontrolled


54
tanks (i.e., non-Stage II VRS) with one noted difference, increased UST emissions related to the


longer shut down periods of the facility.


Spillage EF is for a purge puff nozzle.


55
Source Company/Organization: 

New Hampshire DES Report on MTBE Levels in Groundwater Near GDF. September 30, 

2004. [Submitted by Healy, Inc.] 

Test Scenario: 


NH DES monitored approximately 300 GDF in New Hampshire to determine the extent of


groundwater pollution with MTBE. The GDF monitored included a number of different control


types, including balance, vacuum assist, and some GDF without Stage II VRS controls. MTBE


is an oxygenate additive to gasoline that is used to reduce CO emissions from automobiles and


improve attainment with the NAAQS.


Operating Data: 

None. 

Results and Conclusions Reported: 

The groundwater monitoring data show that a number of the 300 GDF have detectable levels of 

MTBE and a number have exceeded the groundwater limit. The standard for MTBE in 

groundwater is 13 ppb. Approximately 88 GDF exceed the limit, and 51 of these are confirmed 

vacuum assist VRS that are not ORVR-compatible. The table below summarizes the data for the 

GDF. 

Comments: 

None. 

56
Site Historical Recent Last MTBE Type of Site 

No. MTBE range reading, control No. 

high, ppb MTBE, ppb ppb 

1 5,800 44-5,800 480 Exempt 

2 11,000 2,270-4,300 4,300 Gilbarco 

Retrofit 

3 150,000 3,580-7,460 6,250 Balance 

4 NA NA NA Wayne 

Vapor Vac 

5 108,000 55-20,300 55 Balance 

6 NA NA NA Exempt, 

Manifolded 

7 150,000 17,000-

46,000 

46,000 2 pt. Wayne 

Vapor Vac 

8 22,000 Old Data 8,400 2 pt. Wayne 

Vapor Vac 

9 20,000 20-20,000 20 Manifolded, 

Wayne 

Vapor Vac 

10 122,000 165-40,800 40,800 Manifolded, 

Unknown 

11 120,000 27-64,000 64,000 2 pt. Wayne 

Vapor Vac 

12 17,000 2-4,200 2,350 2 pt. Wayne 

Vapor Vac 

13 26,000 44-18,000 57 Wayne 

Vapor Vac 

14 1,040 20.4 to 

1,040 

1,040 2 pt. 

Balance 

15 NA NA NA Exempt 

16 18,000 2,000-

18,000 

2,900 Manifolded, 

Unknown 

17 17,000 180-17,000 2,300 Manifolded, 

Balance 

18 492 ND-492 492 Wayne 

Vapor Vac 

19 50,000 480-50,000 50,000 2 pt. 

Gilbarco 

20 110,000 260-110,000 33,000 2 pt. Wayne 

Vapor Vac 

21 239,000 53,500-

239,000 

239,000 2 pt. 

Gilbarco 

22


23


24


25


26


27


28


29


30


31


32


33


34


35


36


37


38


39


40


41


42


Su in New Hampshire. 

Historical 

MTBE 

high, ppb 

Recent 

range 

MTBE, ppb 

Last MTBE 

reading, 

ppb 

Type of 

control 

NA NA NA Exempt 

NA NA NA Coaxial, 

Exempt 

16,000 272 to 

16,000 

16,000 Gilbarco 

Retrofit 

NA NA NA 2 pt. Gilbarco 

6,500 2,200-6,500 2,200 Manifolded, 

Unknown 

190,000 20,000-

190,000 

33,000 2 pt. Gilbarco 

NA NA NA Exempt 

5,500 2 to 5,500 5,500 Manifolded, 

Gilbarco 

16,000 460 to 

16,000 

16,000 Manifolded, 

Exempt 

NA NA NA Exempt 

27,000 BDL to 550 550 Wayne 

NA NA NA Exempt 

23,500 76 to 3,300 640 Wayne Vapor 

Vac 

67,000 1,800 to 

67,000 

67,000 Manifolded, 

Gilbarco 

1,420 BD to 56 56 Coaxial, 

Exempt 

NA NA NA 2 pt. Gilbarco 

17,000 BDL to 

1,300 

BDL Wayne Vapor 

Vac 

5,830 60.9 to 173 60.9 Coaxial, 

Exempt 

41,000 130 to 

41,000 

3,210 2 pt. Gilbarco 

59,800 444 to 

59,800 

444 2 pt. Wayne 

Vapor Vac 

14,700 660 to 9,080 660 Manifolded, 

Wayne Vapor 

Vac 

mmary of MTBE Concentration Data in Groundwater at GDF

57
Site 

No. 

Historical 

high, ppb 

43 101,000 

44 10,000 

45 605 

46 39,500 

47 1,110,000 

48 9,500 

49 NA 

50 25,000 

51 NA 

52 7,520 

53 LNAPL 

54 149,000 

55 NA 

56 NA 

57 NA 

58 5,000 

59 11,000 

60 18 

61 NA 

62 18,000 

63 88,100 

64 High MTBE in Indoor Air 

Recent 

range, ppb 

Last 

reading, 

ppb 

Type of 

control 

12,200 to 

101,000 

12,200 Manifolded, 

Gilbarco 

Retrofit 

BDL to 

5,200 

5,200 2 pt. Wayne 

Vapor Retrofit 

192 to 605 192 Manifolded, 

Gilbarco 

Retrofit 

815 to 

39,500 

39,500 2 pt. Tokheim 

574,000 to 

1,110,000 

1,110,000 Manifolded, 

Wayne Retrofit 

32 to 3,270 442 2 pt. Balance 

NA NA 2 pt. Gilbarco 

35 to 638 442 2 pt. Balance 

Manifolded 

Gilbarco 

17 to 6,750 325 2 pt. Exempt 

LNAPL LNAPL 2 pt. Wayne 

Vapor Retrofit 

2,400 to 

35,900 

16,400 Manifolded 

Gilbarco 

NA NA Manifolded 

Gilbarco 

NA NA 2 pt. Gilbarco 

NA NA 2 pt. Wayne 

Vapor Vac 

980 to 

3,820 

1,100 Gilbarco 

Retrofit 

1,500 to 

4,300 

2,300 2 pt. Wayne 

Vapor Vac 

18 Gilbarco 

NA NA Exempt 

3,900 to 

18,000 

18,000 Manifolded, 

Wayne Vapor 

Vac 

2,080 to 

88,100 

18,200 Manifolded, 

Unknown 

Site 

No. 

65


66


67


68


69


70


71


72


73


74


75


76


77


78


79


80


81


82


83


84


85


Historical 

high, ppb 

Recent 

range, ppb 

Last 

reading, 

ppb 

Type of 

control 

34,600 356 to 34,600 1,090 2 pt. Wayne 

Vapor Vac 

NA NA NA Exempt 

NA NA NA Balance 

2,510 3 to 2,510 53 2 pt. Healy 

400 

81,500 51,000 to 

81,500 

81,500 Exempt 

33,100 809 to 9,360 9,360 Gilbarco 

6,000 264 to 6,000 264 Exempt 

39,000 130 to 4,500 4,500 Wayne 

Vapor Vac 

2,180 129 to 2,180 129 Coaxial, 

Balance 

NA NA NA 2 pt. 

Unknown 

NA NA NA 2 pt. 

Gilbarco 

130,000 5,600 to 

130,000 

5,600 2 pt. Wayne 

Vapor Vac 

23,200 23,200 23,200 2 pt. Wayne 

Vapor Vac 

NA NA NA Coaxial, 

Balance 

NA NA NA 2 pt. 

Tokheim 

113,000 3,200 to 

55,000 

55,000 2 pt. Healy 

600 

NA NA NA 2 pt. 

Balance 

24,000 79 to 24,000 24,000 Wayne 

8,190 946 to 8,190 946 Balance 

NA NA NA Exempt 

NA NA NA Manifolded, 

Unknown 

2 pt. Wayne 86


Vapor Vac 

2,600 350 to 2,600 440 Wayne 

Vapor Vac 

58

18 
Last 

reading, 

ppb 

Type of 

control 

Site 

No. 

Historical 

high, ppb 

Recent 

range, 

ppb 

87 NA NA 

88 NA NA 

89 5,500 2,500 to 

5,500 

90 168,000 50,400 to 

103,000 

91 NA NA 

92 NA NA 

93 NA NA 

94 NA NA 

95 120,000 880 to 

120,000 

96 50,000 BD to 

50,000 

97 13,000 1,960 to 

13,000 

98 47,200 BDL to 

8,200 

99 24,000 6,800 to 

24,000 

100 24,100 35 to 

24,100 

101 76,900 24,000 to 

76,900 

102 NA NA 

103 58,900 336 to 

20,400 

104 8,380 BDL to 

2,600 

105 NA NA 

NA 2 pt. Gilbarco 

NA Manifolded, 

Gilbarco 

5,500 2 pt. Gilbarco 

50,400 Gilbarco 

4,470 

near tanks 

Exempt 

NA Exempt ? 

NA Exempt 

NA 2 pt. Gilbarco 

880 2 pt. Wayne 

Vapor Vac 

50,000 Gilbarco 

Retrofit 

13,000 Gilbarco 

2,900 Wayne Vapor 

Vac 

6,800 2 pt. Wayne 

Vapor Vac 

24,100 Coaxial, 

Exempt 

35,000 Manifolded, 

Balanced 

NA Manifolded, 

Wayne Vapor 

Vac 

20,400 Manifolded, 

Wayne Vapor 

Vac 

398 2 pt. Tokheim 

NA Manifolded 

Healy Slap 

Lock 

Site 

No. 

106


107


108


109


110


111


112


113


114


115


116


117


118


119


120


121


122


123


124


Historical 

high, ppb 

Recent 

range, ppb 

13,000 3,100 to 

13,000 

NA NA 

140,000 420 to 

140,000 

190,000 970 to 

190,000 

68,000 15,000 

NA NA 

6,400 740 to 

2,000 

50,000 3,400 to 

44,000 

166,000 230 to 

166,000 

5,890 531 to 

2,790 

29,000 22,000 to 

29,000 

121,000 8,760 to 

121,000 

3,100 3,100 

409,000 18,000 to 

140,000 

NA NA 

32,000 9 to 32,000 

2,200 93 to 2,200 

7,900 250 to 

7,900 

30,400 2,620 to 

30,400 

2,610 Coaxial, 

Exempt 

Last 

reading, 

ppb 

Type of 

control 

3,400 Wayne 

Vapor Vac 

NA Exempt 

420 2 pt. 

Gilbarco 

190,000 2 pt. Wayne 

Vapor Vac 

5,000 Wayne 

NA 2 pt. Wayne 

Vapor Vac 

740 Wayne 

44,000 2 pt. Wayne 

Vapor Vac 

230 Manifolded, 

Gilbarco 

Retrofit 

2,000 Gilbarco 

Retrofit 

22,000 Gilbarco 

Retrofit 

10,500 Manifolded, 

Gilbarco 

3,100 Manifolded, 

Gilbarco 

Retrofit 

18,000 Manifolded, 

Gilbarco 

Retrofit 

NA 2 pt. 

Unknown 

17,000 Wayne 

93 2 pt. 

Unknown 

7,900 Balance 

59
Source Company/Organization:


Data Table on Failure Rates for Pressure Decay Testing, Dynamic Backpressure Tests, and


Air-to-Liquid Ratio Tests for 17 States, for June 30, 2003 through September 17, 2004.


[Submitted by Crompco Corporation]


Test Scenario: 


Testing for GDF with Stage II VRS controls was conducted in multiple States (17). Testing


included pressure decay tests (static pressure performance test), dynamic backpressure tests, and


A/L ratio testing. Information on the testing frequency in each State is also provided.


Results and Conclusions:


A summary of the test information is provided in the table. A total of 7,514 pressure decay tests


were conducted over this time period in 17 States. Of the pressure decay tests, approximately 19


percent failed. The failure rate from State to State ranged from 0 percent (only 2 GDF were


tested) to 29 percent. These failures included maintenance attempts by the test technician to


repair tank fittings, dispenser fittings, and hanging hardware while onsite when a GDF failed an


initial try and then retesting. 


A number of dynamic backpressure tests were conducted, with 3,974 tests on the gasoline (wet)


side and 3,916 on the vapor (dry) side. These tests check for any blockage in the gasoline or


vapor piping or hoses. Overall, approximately 6.5 percent of the wet backpressure tests were


failures (ranging from 0 to 33 percent from State to State) and 3.4 percent of the dry backpressure


tests were failures (ranges from 0 to 25 percent). 


There were 4,313 A/L ratio tests summarized in the data. Approximately 27 percent of the tests


were failures; these tests are considered to be failures if even one fueling point fails and cannot


be repaired by the technician or if a fueling point is out of order when the test is conducted. All


fueling points must be working properly to pass the test. 


Comments: 

None. 

60
61
Source Company/Organization:


Stage II Vapor Recovery Pilot Testing Project. Prepared by the Vermont Department of


Environmental Conservation. April 26, 2000. [Submitted by NESCAUM.]


Test Scenario:


In 1996, Vermont adopted a regulation requiring Stage II VRS on all GDF that pump more than 

400,000 gallons of gasoline per year. The implementation period ranged from December 31, 

1997 (for stations pumping more than 1,200,000 gallons per year) to December 31, 2000 (for 

stations pumping more than 400,000 gallons per year). 

A total of 32 stations with Stage II VRS were tested by the State of Vermont, after they had been 

operating for at least 1 year and for most, it had been at least 12 months since they were last 

tested. (However, 3 GDF had been tested just 4 months before this testing.) The stations were 

heavily weighted toward bootless vacuum-assist stage II systems, with only 6 of the stations 

tested being equipped with balance systems. 

Tests conducted included: (1) the pressure decay test at all stations, (2) the air-to-liquid (A/L) 

ratio test at all stations equipped with bootless vacuum-assist systems, and (3) the vacuum line 

integrity test at two stations using the Healy Systems, Inc. VRS with a central vacuum pump. 

Testing was performed on an “as is” condition (i.e., without first doing any maintenance to 

facilitate passing the test, such as tightening loose tank top fitting or replacing worn or broken 

parts). 

The testing included balance systems and four varieties of vacuum-assist systems as shown in 

Table 1: 

Number 

Tested 

Table 1. s of Stage II VRS 

Type of System 

Type Tested 

Percentage of Total 

Stations Tested 

Balance 6 19 

Franklin Intellivac 1 3 

Gilbarco Vapor Vac 8 25 

He aly System s with M ode l 600 No zzle 2 6 

W ayne Vac 15 47 

Total 32 100 

Emissions Testing: 

None. 

Operating Data: 

None. 

62
Results and Conclusions Reported: 

The pressure decay results are in Tables 2 through 5. The total number of system components 

tested included 90 USTs, 128 gasoline dispensers, and 360 gasoline nozzles. As shown in Tables 

2 and 3, the results do not provide definitive evidence for how many months a GDF is likely to 

maintain compliance with the pressure integrity standard but note that the 3 GDF that had been 

tested within the last 4 months all passed the pressure decay test. At most GDF that failed, more 

than one leaking component contributed to the test failure. The two components most frequently 

observed to be leaking were fill caps (41 percent of all test failures had fill caps found to be 

leaking) and Stage I poppet valves, dry breaks (41 percent of all test failures had Stage I poppet 

valves found to be leaking) (totals add to more than 100 percent because multiple components 

contributed to test failure). 

Vacuum Line Integrity Test: Vacuum line integrity testing was performed at the two stations 

equipped with the Healy Systems Inc. system and using a central vacuum source. Both stations 

passed this test on the initial attempt. 

Air-to-Liquid Ratio Test: The A/L ratio test was performed at 26 stations and involved testing of 

298 nozzles. Test results are presented in Table 6. The values in Table 5 are read from Figure 3 

of the report; therefore, the numbers may be slightly off. 

The Vermont Agency of Natural Resources concluded that “it is apparent that a significant 

number of gasoline stations cannot pass a pressure decay test without ongoing maintenance. The 

pressure integrity of Stage II systems degrades over time and it is evident that most gasoline 

stations would not pass a pressure decay test by the time their five year retesting requirement 

comes due.” 

The Vermont Agency of Natural Resources also concluded that the A/L testing results indicate a 

high compliance rate with the A/L ratio performance standard. 

Table 2. 

Numb er of Stations Percentage of Total 

Stations 

All Stations 31 100 

Pass 10 32 

Fail 21 68 

Vacuum A ssist Stations 25 

Pass 10 40 

Fail 15 60 

Balance Stations 6 

Pass 0 0 

Initial Pressure Decay Test Results 

Fail 6 100 

63
Table 3. ressure Decay Test Results – All Stations 

Percent of Total Stations 

Pass – W ithin Allowed Leak Rate 32 

Fail – U p to 1 0% Abo ve Allowed Leak Rate 26 

Fail – B etwee n 10 % a nd 5 0% Abo ve Allowed Leak Rate 13 

Fail – G reater than 50% Abo ve Allowed Leak Rate 29 

P

Table 4. Equipment Problems that Contributed to a Pressure Decay Test Failure 

Percent of Failing Stations 

Where Component Was a Factor 

Fill Cap 41 

Stage I Poppet Valves 41 

Fill Adaptor 32 

Spill Bucket Drain Valve 27 

Nozzle* 27 

Breakaway 14 

In-Tank Monitor 5 

Submersible Pump 5 

* Note: Nozzles were a contributing factor only at balance stations. 

Table 5. 

Part Numb er Leaking % Leaking, Out of Total 

Number Tested 

Fill Cap 11 12 

Fill Adaptor 9 10 

Spill Bucket Drain Valve 12 not determined 

Stage I Poppet V alve 15 27 

In-Tank Monitor 3 not determined 

Submersible Pump 1 1 

Ba lance System No zzle 13 23 

Breakaway 3 <1 

Parts Found Leaking During Pressure Decay Tests 

64
Table 6. Air-to-Liquid Testing Results for Each Type of System 

Status Percent of Nozzles

W ithin Allowable Range 

Fail– Within 10% 

of Allowable Range 

Fail– Between 10% and 50% 

of Allowable Range 

W ayneVac Gilbarco 

Vapor Vac 

He aly Fran klin 

Intellivac 

85 94 92 100 

11 4 4 0 

2 2 4 0 

Fail– Greater than 50% 

of Allowable Range 

2 0 0 0 

Number of Systems Tested: WayneVac = 15 (186 nozzles); Gilbarco VaporVac = 8 (48 nozzles); 

Healy = 2 (56 nozzles); Franklin = 1 (8 nozzles). 

Comments: 

This testing did not include emission measurements, however, the testing does indicate that, at 

least for the pressure decay test, the systems fail the test without ongoing routine maintenance. 

The A/L test results were more favorable regarding compliance. 

65
Source Company/Organization:


EPA In-Use Evaporative Testing, Ann Arbor, Michigan. April 15, 2003. [Submitted by NC


Petroleum Marketers Association]


Test Scenario: 


Two-day evaporative system testing was conducted on ORVR vehicles of various ages. After the


two-day evaporative test, the vehicles were refueled to a full tank of gasoline and any refueling


problems or fuel spitback was noted. The odometer readings ranged from 6,800 to 190,000


miles, with an average mileage of 45,000 miles. While the evaporative system testing does not


provide data on the control efficiency of ORVR canisters, it does provide data indicating that the


ORVR system is operating correctly.


Results and Conclusions:


A total of 32 ORVR vehicles were tested. Of these vehicles, 28 passed the evaporative testing,


which represents a 12 percent failure rate.


Comments: 

None. 

66
Comments 

Pass 

Pass 

Pass 

Kinked canister supply hose (after dealer 

performed Kia ORVR valve recall). 

Pass 

Pass 

Pass 

Pass 

Pass 

Failed 2.5 Gram Standard 

Retest, Failed 2.5 Gram Standard 

Pass 

Pass 

Pass 

Pass 

Pass 

Shed N/A 

Pass 

FAIL-2nd veh passed--no followup action 

PASS 

PASS 

PASS 

PASS 

PASS 

PASS 

PASS 

PASS 

PASS 

PASS 

PASS 

PASS 

PASS 

Count Pass 28 

Yes/No 

No 

No 

No 

Yes 

No 

No 

No 

No 

No 

No 

No 

No 

No 

No 

No 

No 

No 

No 

No 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

NO 

Total Evap 

Grams Grams 

0.51 

0.60 

0.78 

NA 

0.63 

0.75 

2.39 

0.71 

0.40 

3.69 

4.38 

0.53 

0.64 

0.93 

0.79 

0.77 

N/A 

1.44 

3.09 

0.77 

0.53 

0.95 

0.55 

0.84 

0.99 

0.99 

0.59 

1.01 

0.95 

1.2 

0.9 

1.2 

Hot Soak 

Grams 

0.06 

0.04 

0.07 

NA 

0.08 

0.04 

0.32 

0.18 

0.05 

0.16 

0.17 

0.05 

0.09 

0.07 

0.04 

0.07 

N/A 

0.21 

0.19 

0.09 

0.04 

0.06 

0.11 

0.04 

0.07 

0.13 0.09 

0.11 

0.05 

0.07 

0.12 

0.11 

Diurnal 

0.45 

0.56 

0.72 

NA 

0.55 

0.71 

2.07 

0.53 

0.35 

3.53 

4.21 

0.48 

0.55 

0.87 

0.75 

0.70 

N/A 

1.23 

2.9 

1.11 

0.73 

0.47 

0.84 

0.77 

0.85 

0.89 

0.79 

1.15 

0.52 

0.89 

0.84 

0.5 

EPA In-Use Evaporative Testing 

Ann Arbor, Michigan 

XCRXR0101GBF 

XFMXR0115BAE 

XKMXR0100A02 

XKMXR0100A02 

XVWXR0110234 

XJCXR0121M2X 

XJCXR0121M2X 

XDWXR0095AOL 

XFJXR01251BB 

XFJXR01251BB 

WTKXR0125BFA 

WVWXR0110234 

XHNXR0130AAA 

XTKXR0125BFA 

XFJXR01251BB 

XGMXR0124919 

XBMXR0136E46 

XGMXR0080902 

XFMXR0080BAE 

XGMXR0080902 

YTKXR0125BFB 

YNSXR0110RCC 

YTYXR0135AK1 

YVWXR0110234 

YVVXR0133X48 

YVVXR0133X48 

YVVXR0133X48 

YHNXR0099AAD 

YGMXR0124919 

YHNXR0160AAZ 

Evap Family* 

XTYXR0135AKI 

YGMXR013910 

Eng Fam/ Test Grp 

XCRXV03.5VBO 

XFMXV03.0VBB 

XKMXV01.8A02 

XKMXV01.8A02 

XVWXV02.0222 

XTYXV03.0BBA 

XJCXV04.0BN4 

XJCXV04.0BN4 

XDWXV02.2DO1 

XFJXV02.5CAC 

XFJXV02.5CAC 

WTKXV02.0VBA 

WVWXV02.0226 

XHNXV02.3PA3 

XTKXV02.0VBA 

XFJXV02.5CAC 

XGMXV03.0061 

XBMXV02.8LEV 

XGMXV01.9001 

XFMXV02.0VBA 

XGMXV01.9001 

YTKXV01.8VBB 

YNSXV03.0A6A 

YTYXV02.2XBA 

YVWXV01.8228 

YVVXV2.78EN3 

YVVXV2.78EN3 

1VVXT2.43L5T 

YHNXV01.6CA3 

YGMXV04.6065 

YGMXV04.6065 

YHNV03.5YA3 

17,917 

42,538 

35,639 

38,136 

34,947 

16,195 

16,374 

19,624 

34,511 

39,197 

39,197 

42,618 

7,162 

187,066 

125,799 

49,632 

13,801 

53,933 

74,642 

53,396 

57,227 

17,615 

52,002 43,345 

26,814 26,701 

37,331 

6,822 

74,483 

24,499 

66,685 

55,307 

6,822 

Odometer 

Liters 

187,066 

Miles 

44,724 

Displ 

3.5 

3.0 

1.8 

1.8 

2.0 

3.0 

4.0 

4.0 

2.2 

2.5 

2.5 

2.0 

2.0 

2.3 

2.0 

2.5 

3.0 

2.8 

1.9 

2.0 

1.9 

1.8 

3.0 

2.2 

1.8 

2.8 

2.8 

2.4 

1.6 

4.6 

2.4 

3.5 

min 

max 

avg 

Mercury Sable 

Legacy Outack 

Legacy Outack 

Cadillac Catera 

Model 

Vanden Plas 

Saturn SL1 

Saturn SL1 

PROTÉGÉ 

Acura 3.5RL 

* R as the fifth letter in the Evaporative Family code is ORVR. 

Concorde 

Sephia 

Sephia 

Beetle 

Solara 

XJ8 

Leganza 

626LX 

Beetle 

Accord 

626 

Legacy 

328i 

ESCORT 

MAXIMA 

Camry 

BEETLE 

S 80 T6 

S 80 T6 

V70 XC 

Civic LX 

Deville 

Cavalier 

Chrysler 

Daewoo 

Subaru 

Subaru 

Subaru 

MAZDA NISSAN 

Mfr 

Ford 

Kia 

Kia 

VW 

Toyota 

Jaguar 

Jaguar 

Mazda 

VW 

Honda 

Mazda 

GM 

BMW 

GM 

FORD GM 

Toyota VW 

Volvo Volvo 

Volvo Honda 

GM 

GM 

Honda 

Class- Veh ID 

F100--0022 

F102-0019 

E104-0018 

E104-0021 

E106-0005 

E108-0006 

E114-0305 

E114-0309 

E118-0023 

E120-0027 

E120-0027 

D124-0061 

D126-0053 

F112-0025 

F117-0003 

E121-0044 

F110-0077 

F123-0085 

F127-0002 

F133-0008 

F127-0027 

F142-0019 

F145-0046 

F146-0011 

F150-0016 

F154-0020 F154-0114 

F160-0024 G115-0023 

G108-0325 G121-0049 

G135-0100 

Model 

Year 

1999 

1999 

1999 

1999 

1999 

1999 

1999 

1999 

1999 

1999 

1999 

1998 

1999 

1999 

1999 

1999 

1999 

1999 

1999 

1999 

1999 

2000 

2000 

2000 

2000 

2000 

2000 

2001 

2000 

2000 

2000 

2000 

10/30/2001 

11/15/2001 

05-22-01 

05-18-01 

05-25-01 

07-17-01 

07-25-01 

09-07-01 

08-15-01 

12-04-01 

01-09-02 

12-19-00 

01-05-01 

01-18-02 

01-30-02 

01-30-02 

02-02-02 

03-01-02 

03-12-02 

Test Date 

04-10-02 

05-01-02 

05-08-02 

05-15-02 

06-10-02 

06-21-02 

07-19-02 

07-26-02 

08-04-02 

12-20-02 

12-11-02 

01-21-03 

03-19-03 

67
Source Company/Organization:


EPA In-Use Verification Program (IUVP), Ann Arbor, Michigan. No date given, but likely


2004 and later.


Test Scenario: 


Beginning in 2004, EPA has instituted an in-use testing program called the In-Use Verification


Program (IUVP). The IUVP requires manufacturers to test customer-owned and -operated


vehicles, including 1-year old and 5-year old vehicles (minimum 50,000 miles) are tested. EPA


began receiving test data in calendar year 2005 on high mileage (50,000+) model years 2001


vehicles and low-mileage (10,000+) model year 2004 vehicles. EPA also conducts confirmatory


in-use tests on approximately 150 vehicles per year to verify the results of the manufacturer in-


use testing. These are EPA’s preliminary testing data from this program.


Results and Conclusions:


Testing on the ORVR canister’s outlet HC concentration by FTP method 24 was conducted on a


total of 151 ORVR-equipped vehicles. Overall, 9.3 percent of the vehicles (14 out of 151) had


emissions greater than the 0.2 g/gal limit. Of the high-mileage vehicles, 12.8 percent (6 out of


47) had emissions greater than the 0.2 g/gal limit. Of the low-mileage vehicles, 7.7 percent (8 

out of 104) had emissions greater than the 0.2 g/gal limit. 

Comments: 

None. 

Test Summary for Outlet Concentrations on In-Use ORVR Canisters. 

Test Result Overall Low Mileage High Mileage 

Number Percentage Number Percentage Number Percentage 

< 0.2 g/gal 137 90.7 96 92.3 41 87.2 

> 0.2 g/gal 14 9.3 8 7.7 6 12.8 

Total 151 100 104 100 47 100 

68
 Appendix B 

NESCAUM Widespread Use Study Supporting Documentation
I. Purpose

The purpose of Appendix B is to document and explain the equations used in the 

algorithm analysis for determining widespread use. 

II. MOBILE6 Calculations 

 A. Definition (a) 

The following equations were used to determine a widespread use date for 

definition (a) [Note: the equations for definition (a) are not exact, because the 

equation is calculating the percentage of ORVR-equipped vehicles in a specific 

vehicle group, not the entire fleet]: 

Equation (1): 

WT

n

i

ORVRFLEET PER ORVRPI *VEH

25

1

_ ∑

=

=

=

Where: 

 ORVRFLEET_PER = Percentage of vehicle fleet equipped with ORVR in a given year. 

 i = Vehicle age. The vehicle age for a specific vehicle type ranges 

from one to twenty-five years, with vehicles twenty-five years 

and older grouped together. 

 ORVRPI = ORVR phase-in rate, based on estimated MY (MYE) of vehicle. 

 VEHWT = Weighted fractional average of the number of VMT/day in a 

given CY for a specific vehicle type of a given age in relation to 

the total VMT/day in a given CY for all vehicle types of all ages. 

See Equation (5). 

Equation (2): 

MYE = CY − i +1

 

Where: MYE = Estimated MY of vehicle. 

 CY = Calendar year. 

 i = Vehicle age. The vehicle age for a specific vehicle type ranges 

from one to twenty-five years, with vehicles twenty-five years 

and older grouped together. 

Equation (2) is used to estimate the MY of the vehicle by subtracting the CY in question 

by the vehicle’s age then adding one. For example, if the CY of interest is 2005 and 

vehicles of age one are being considered, then the calculation yields a MY 2005. 
Intuitively, one would expect the result to be MY 2004 for a car of age one in the year 

2005, however, ages are based on whole numbers and as such, a car of age one could 

possibly be a brand new car (i.e., MY 2005). 

Equation (3): 

∑

=

=

= n 25

i 1

VEHWT VADSVT *VMTSVT / (VADSVT *VMTSVT)

Where: VEHWT = Weighted fractional average of the number of VMT/day in a 

given CY for a specific vehicle type of a given age in relation to 

the total VMT/day in a given CY for all vehicle types of all ages. 

 VADSVT = Vehicle age distribution (fraction) in a model year for a specific 

vehicle type. 

 VMTSVT = VMT per day in a given CY for a specific vehicle type, mile/day. 

 i = Vehicle age. The vehicle age for a specific vehicle type ranges 

from one to twenty-five years, with vehicles twenty-five years 

and older grouped together. 

Equation (3) is used to calculate the weighted fractional average of VMT per day in a 

given CY for a specific vehicle type of a given age in relation to the VMT per day in the 

same CY for all vehicle types of all ages. The following methodology was used to 

calculate the weighted fractional average: 

1. The vehicle age distribution (fractional value) of a specific vehicle type in 

a given MY is multiplied by the number of VMT per day in a given CY 

for a specific vehicle type.

2. For ages one through twenty-five for the specific vehicle type in a given 

CY, multiply the vehicle age distribution of the specific vehicle type in a 

given MY by the number of VMT per day in a given CY for the specific 

vehicle type (i.e., twenty-five separate calculations). The total VMT per 

day for a specific vehicle type in a given CY is the sum of the individual 

twenty-five calculations. .

3. Divide the result from step one by the result from step 2.

 Equation (4): 

VMTSVT = AMAR / 365

Where: VMTSVT = VMT per day in a given CY for a specific vehicle type, mile/day. 

AMAR = Annual mileage accumulation rate for a specific vehicle type of a 

given age, miles/yr. 
Equation (4) is used to determine VMT per summer day for a specific vehicle type of a 

given age in miles per day. This value is determined by dividing the annual mileage 

accumulation rate for a specific vehicle type of a given age by the number of days per 

year (i.e., 365 days per CY). 

B. Definition (b) 

The following equations in conjunction with the equations used for determining a 

widespread use date for definition (a) were used to determine a widespread use date for 

definition (b):

Equation (5): 

∑ ∑ = =

= j vehicletypeORVRFLEET PER GASVMT MIX GASVMT _ MIX

j vehicle type

VMTORVR_PER [ _ * _ ] /

Where: 

 VMTORVR_PER = Percentage of VMT by ORVR-equipped vehicles in a given CY. 

 ORVRFLEET_PER = Percentage of vehicle fleet equipped with ORVR in a given CY. 

See Equation (1). 

 GASVMT_MIX = Gasoline component of the VMT fractional mix. 

 

Equation (6): 

WT F M

n

i

GASVMT MIX (1 VEH * DS )*VMT

25

1

_ ∑

=

=

= −

Where: 

 GASVMT_MIX = Gasoline component of the VMT fractional mix. 

 i = Vehicle age. The vehicle age for a specific vehicle type ranges 

from one to twenty-five years, with vehicles twenty-five years 

and older grouped together. 

 VEHWT = Weighted fractional average of the number of VMT/day in a 

given CY for a specific vehicle type of a given age in relation to 

the total VMT/day in a given CY for all vehicle types of all ages. 

See Equation (3). 

 DSF = Diesel sales fraction for a specific vehicle type, based on MYE of 

vehicle. 

 VMTM = VMT fractional mix (fuel independent) in a given CY for a 

specific vehicle type. 
 C. Definition (c) 

The following equations in conjunction with Equations (2), (3), and (4) were used 

to determine a widespread use date for definition (c): 

Equation (7): 

∑ =

=

j vehicle type

ES2 [VEHR *AFE*GU / GUT]

Where: ES2 = Stage II VRS emissions (without ORVR) on a summer day in a 

given CY for all vehicle types, grams/gal. 

 VEHR = Vehicle refueling and spillage emissions in a given CY for a 

specific vehicle type utilizing Stage II VRS, grams/mile. 

 AFE = Average fuel economy for a specific vehicle type in a given CY, 

miles/gal. 

 GU = Gasoline usage in a given CY for a specific vehicle type, gal/day. 

 GUT = Total gasoline usage for a given CY for all vehicle types, 

gal/day. 

Equation (7) was used to calculate Stage II VRS emissions in grams per gal, without 

ORVR, in a given CY for each vehicle type (based on summertime data). The following 

methodology was used to calculate emissions: 

1. For a specific CY, calculate the Stage II VRS emissions associated with 

each individual vehicle type. This calculation is done by multiplying the 

calculated vehicle refueling and spillage emissions in grams per mile for 

the specific vehicle type in question by the average fuel economy (AFE) in 

miles per gal of the vehicle type, then by the percentage of gasoline used 

in the CY by the specific vehicle type (i.e., ratio of the gasoline usage of 

the specific vehicle type in gal per day to total gasoline usage for all 

vehicle types in gal per day in a given CY). 

2. Total Stage II VRS emissions in a given CY equals the sum of the 

emissions calculated for each individual vehicle type. 

Equation (8): 

∑

=

=

= + n 25

i 1

VEHR [(ER / FE* (1-(CEIU / 100)) (SP / FE))*VEHWT]

Where: VEHR = Vehicle refueling and spillage emissions in a given CY for a 

specific vehicle type utilizing Stage II VRS, grams/mile. 

 i = Vehicle age. The vehicle age for a specific vehicle type ranges 

from one to twenty-five years, with vehicles twenty-five years 

and older grouped together. 

 ER = Uncontrolled displacement losses from vehicle refueling, 

grams/gal. 

 FE = Fuel economy of vehicle, based on MYE of vehicle, miles/gal. 
 CEIU = In-use control efficiency of Stage II VRS. 

 SP = Spillage emissions factor, grams/gal. 

 VEHWT = Weighted fractional average of the number of VMT/day in a 

given CY for a specific vehicle type of a given age in relation to 

the total VMT/day in a given CY for all vehicle types of all ages. 

See Equation (3). 

Equation (8) was used to calculate vehicle refueling and spillage emissions in a given CY 

for a specific vehicle type in grams per mile. The following methodology was used to 

calculate emissions: 

1. Emissions were calculated for a specific vehicle type from ages one to 

twenty-five (vehicles twenty-five years and older are grouped together), 

resulting in twenty-five calculations per individual vehicle type. Each 

calculation consisted of dividing the calculated uncontrolled displacement 

emissions from vehicle refueling in grams per gal by the fuel economy 

(FE) of the vehicle in miles per gal. The FE is based on the estimated 

model year (MY) of the vehicle type at a given age. 

2. The result from step 1 is multiplied by the percentage of emissions not 

controlled by the Stage II VRS (i.e., one minus the in-use control 

efficiency).

3. The result from step 3 is added to the emissions attributed to spillage. 

Spillage emissions are calculated by dividing the spillage emissions factor 

in grams per gal by the FE of the vehicle in miles per gal. 

4. The result from step 3 is multiplied by the weighted fractional average of 

the number of vehicle miles traveled (VMT) per day in the given CY for 

the specific vehicle type of a given age in relation to the total VMT per 

day in the same CY for all vehicle types of all ages. 

5. Total vehicle refueling and spillage emissions in a given CY equals the 

sum of emissions calculated from ages one to twenty-five for a specific 

vehicle type.

Equation (9): 

ER = (-5.909) -(0.0949 *∆T) + (0.0884 *TD) + (0.485∗ RVP)

Where: ER = Uncontrolled displacement losses from vehicle refueling (AP-42 

equation 6), grams/gal. 

∆T = Difference between temperature of fuel in vehicle tank and 

temperature of dispensed fuel, °F. 

 TD = Temperature of dispensed fuel, °F. 

 RVP = Reid vapor pressure, psia. 

Equation (9) is taken from AP-42 (Chapter 5.2 Transportation and Marketing of 

Petroleum Liquids, Equation 6) to calculate uncontrolled displacement losses from 
vehicle refueling in grams per gal. This equation uses constants and takes into account 

the temperature difference between the fuel in the vehicle fuel tank and the temperature 

of the dispensed fuel, as well as the RVP of the fuel. 

Equation (10): 

∑

=

=

= 25

1

1/ (1/ * ) n

i

AFE FE VEHWT

Where: AFE = Average fuel economy for a specific vehicle type in a given CY, 

miles/gal. 

 i = Vehicle age. The vehicle age for a specific vehicle type ranges 

from one to twenty-five years, with vehicles twenty-five years 

and older grouped together. 

 FE = Fuel economy of vehicle, based on MYE of vehicle, miles/gal. 

 VEHWT = Weighted fractional average of the number of VMT/day in a 

given CY for a specific vehicle type of a given age in relation to 

the total VMT/day in a given CY for all vehicle types of all ages. 

See Equation (3). 

Equation (10) calculates the AFE for a specific vehicle type in a given CY in miles per 

gal. The following methodology was used to calculate the average fuel economy: 

1. Divide the weighted fractional average of the number of VMT/day in a 

given CY for a specific vehicle type of a given age by the vehicle type’s 

fuel economy at the given age.

2. Perform step 1 for all ages one to twenty-five.

3. Sum each result from step 2 to get a total sum.

4. Take the inverse of the total sum.
Equation (11): 

GU VEH DSF VMTM VMTT AFE n

i

[(1 ( WT * )]* * /

25

1

∑

=

=

= −

Where: GU = Gasoline usage in a given CY for a specific vehicle type, gal/day. 

 i = Vehicle age. The vehicle age for a specific vehicle type ranges 

from one to twenty-five years, with vehicles twenty-five years 

and older grouped together. 

 VEHWT = Weighted fractional average of the number of VMT/day in a 

given CY for a specific vehicle type of a given age in relation to 

the total VMT/day in a given CY for all vehicle types of all ages. 

See Equation (3). 

 DSF = Diesel sales fraction for a specific vehicle type, based on MYE of 

vehicle. 

 VMTM = VMT fractional mix (fuel independent) in a given CY for a 

specific vehicle type. 

 VMTT = Total number of VMT per day in a given CY for all vehicle 

types. 

Equation (11) calculates the gasoline usage for a summer day in a given CY for a specific 

vehicle type in gallons per day. The following methodology was used to calculate 

gasoline usage: 

1. Multiply the weighted fractional average of the number of VMT per day in 

a given CY for a specific vehicle type of a given age by the diesel sales 

fraction of the specific vehicle type, which is based on the estimated MY 

of the vehicle type.

2. Perform step 1 for ages one to twenty-five.

3. Sum each result from step 2 to get a total sum.

4. Subtract one from the result obtained in step 3 (i.e., only account for 

gasoline fueled vehicles).

5. Multiply result from step 4 by the VMT fractional mix value then by the 

total number of VMT per summer day in a given CY for all vehicle types.

6. Divide the result from step 5 by the AFE for the specific vehicle type in a 

given CY.

Equation (12): 

∑ =

=

j vehicletype

GUT GU

Where: GUT = Total gasoline usage for a given CY for all vehicle types, 

gal/day. 

 GU = Gasoline usage in a given CY for a specific vehicle type, gal/day. 
Equation (12) is used to determine total vehicle gasoline usage in a given CY for all 

vehicle types in gallons per day. This value is calculated by summing the gasoline usage 

for each specific vehicle type in gallons per day. 

 

Equation (13): 

∑ =

=

j vehicletype

EORVR (VEHORVR * AFE*GU / GUT )

Where: EORVR = ORVR emissions (without Stage II) on a summer day in a given 

CY for all vehicle types, grams/gal. 

 VEHORVR = Vehicle refueling and spillage emissions in a given CY for a 

specific vehicle type utilizing ORVR canisters, grams/mile. 

 AFE = Average fuel economy for a specific vehicle type in a given CY, 

miles/gal. 

 GU = Gasoline usage for a given CY for a specific vehicle type, 

gal/day. 

 GUT = Total gasoline usage for a given CY for all vehicle types, 

gal/day. 

Equation (13) is used to calculate ORVR emissions (without Stage II VRS) on a summer 

day in a given CY for all vehicle types in grams per gal. The following methodology was 

used to calculate ORVR emissions: 

1. Multiply vehicle refueling and spillage emissions in a given CY for a 

specific vehicle type utilizing ORVR in grams per gal by the AFE for the 

specific vehicle type in a given CY in miles per gal. 

2. Multiply the result in step 1 by the ratio of gasoline usage in a given CY 

for the specific vehicle type in gallons per day to the total gasoline usage 

in a given CY for all vehicle types in gallons per day. 

3. Repeat steps 1 and 2 for each vehicle types. 

4. Sum each result from step 2 to get a total sum of ORVR emissions. 
Equation (14): 

∑

=

=

= + − +

25

1

[( / *( (1 )) )* ] n

i

VEHORVR ER FE ORVRVAR ORVRPI SPADJ VEHWT

Where: VEHORVR = Vehicle refueling and spillage emissions in a given CY for a 

specific vehicle type utilizing ORVR canisters, grams/mile. 

 i = Vehicle age. The vehicle age for a specific vehicle type ranges 

from one to twenty-five years, with vehicles twenty-five years 

and older grouped together. 

 ER = Uncontrolled displacement losses from vehicle refueling, 

grams/gal. 

 FE = Fuel economy of vehicle, based on MYE of vehicle, miles/gal. 

 ORVRVAR = ORVR emission rate adjustment for tampering and phase-in rate 

for model year. 

 ORVRPI = ORVR phase-in rate, based on MYE of vehicle. 

 SPADJ = Adjusted spillage emissions, grams/mile. 

 VEHWT = Weighted fractional average of the number of VMT/day in a 

given CY for a specific vehicle type of a given age in relation to 

the total VMT/day in a given CY for all vehicle types of all ages. 

See Equation (3). 

Equation (15): 

ORVRVAR = (1− ORVRCE)*(1−TPR)*ORVRPI + (TPR *ORVRPI)

Where: ORVRVAR = ORVR emission rate adjustment for tampering and phase-in rate 

for model year. 

 ORVRCE = Control efficiency of ORVR technology. 

 TPR = Tampering rate for ORVR canisters. 

 ORVRPI = ORVR phase-in rate, based on MYE of vehicle. 

Equation (16): 

SPADJ = SP / FE *(ORVRPI *(1− SPORVR) +1− ORVRPI)

Where: SPADJ = Adjusted spillage emissions, grams/mile. 

 SP = Spillage emissions factor, grams/gal. 

 FE = Fuel economy of vehicle, based on MYE of vehicle, miles/gal. 

 ORVRPI = ORVR phase-in rate, based on MYE of vehicle. 

 SPORVR = ORVR control efficiency for spillage.

Equation (16) is used to estimate the spillage emissions associated with ORVR-equipped 

vehicles in grams/gal. The following methodology was used to calculate ORVR spillage 

emissions: 
1. Divide the spillage emissions factor in grams per gallon by the FE of the 

specific vehicle type of a specific MY in miles per gallon. 

D. Definition (c2) 

The following equations in conjunction with Equations (2), (3), (4), (9), (10), 

(11), (12), (13), (14), (15), and (16) were used to determine a widespread use date for 

definition (c2): 
Equation (17): 

∑ =

= + +

j vehicletype

EINC [(VEHCOM VEHINC VEHADJ )* AFE *GU / GUT ]

 

Where: EINC = Emissions from incompatible Stage II and ORVR technologies 

on a summer day in a given CY for all vehicle types, grams/gal. 

 VEHCOM = Vehicle refueling and spillage emissions in a given CY for a 

specific vehicle type utilizing both Stage II VRS and ORVR 

canisters (compatible technologies), grams/mile. 

 VEHINC = Vehicle refueling and spillage emissions in a given CY for a 

specific vehicle type utilizing both Stage II VRS and ORVR 

canisters (incompatible technologies), grams/mile. 

 VEHADJ = Vehicle refueling and spillage emissions in a given CY for a 

specific vehicle type utilizing ORVR canisters at an adjusted 

control efficiency, grams/mile. 

 AFE = Average fuel economy for a specific vehicle type in a given CY, 

miles/gal. See Equation (10). 

 GU = Gasoline usage for a given CY for a specific vehicle type, 

gal/day. See Equation (11). 

 GUT = Total gasoline usage for a given CY for all vehicle types, 

gal/day. See Equation (12). 

Equation (18): 

∑

=

=

= − + − − +

25

1

[( / *( *(1 /100) (1 )*(1 /100)) )* ] n

i

VEHCOM ER FE ORVRVAR CEIU ORVRPI CEIU SPADJ VEHWT

Where: VEHCOM = Vehicle refueling and spillage emissions in a given CY for a 

specific vehicle type utilizing both Stage II VRS and ORVR 

canisters (compatible technologies), grams/mile. 

 i = Vehicle age. The vehicle age for a specific vehicle type ranges 

from one to twenty-five years, with vehicles twenty-five years 

and older grouped together. 

 ER = Uncontrolled displacement losses from vehicle refueling, 

grams/gal. See Equation (9) 

 FE = Fuel economy of vehicle, based on MYE of vehicle, miles/gal. 

 ORVRVAR = See Equation (15). 

 CEIU = In-use control efficiency of Stage II VRS. 

 ORVRPI = ORVR phase-in rate, based on MYE of vehicle. 

 SPADJ = Adjusted spillage emissions, gram/gal. See Equation (16). 

 VEHWT = Weighted fractional average of the number of VMT/day in a 

given CY for a specific vehicle type of a given age in relation to 

the total VMT/day in a given CY for all vehicle types of all ages. 

See Equation (3). 
Equation (19): 

∑

=

=

= − 25

1

[ / *(1 )* * ] n

i

VEHINC INCE FE TPR ORVRPI VEHWT

Where: VEHINC = Vehicle refueling and spillage emissions in a given CY for a 

specific vehicle type utilizing incompatible Stage II VRS and 

ORVR canisters, grams/mile. 

 i = Vehicle age. The vehicle age for a specific vehicle type ranges 

from one to twenty-five years, with vehicles twenty-five years 

and older grouped together. 

 INCE = Incompatible emissions from Stage II and ORVR technologies, 

grams/gal. 

 FE = Fuel economy of vehicle, based on MYE of vehicle, miles/gal. 

 TPR = Tampering rate for ORVR canisters. 

 ORVRPI = ORVR phase-in rate, based on MYE of vehicle. 

 VEHWT = Weighted fractional average of the number of VMT/day in a 

given CY for a specific vehicle type of a given age in relation to 

the total VMT/day in a given CY for all vehicle types of all ages. 

See Equation (3). 

Equation (20): 

INCE = EE *PVPER *(1− ORVRMS)*(1− ORVRPROC)

Where: INCE = Incompatible emissions from Stage II and ORVR technologies, 

grams/gal. 

 EE = Excess emissions from incompatibility of Stage II and ORVR 

technologies, grams/gal. 

 PVPER = Adjusted percentage of GDFs equipped with functioning assist 

Stage II VRS and P/V valves on UST vents. 

 ORVRMS = Percentage of ORVR canisters with mechanical seals. 

 ORVRPROC = Percentage of vacuum assist Stage II with processors. 

Equation (21): 

EE = ((GILEE −WAEE) /(GILAL −WAAL)*VAAL + (GILEE − ((GILEE −WAEE) /(GILAL −WAAL)*GILAL)))*0.4536*ER /(8.4*0.4536)

 Where: EE = Excess emissions from incompatibility of Stage II and ORVR 

technologies, grams/gal. 
GILEE = Excess emissions for the Gilbarco vacuum assist VRS, lb/1,000 

gal.1

 WAEE = Excess emissions for the Dresser Wayne vacuum assist VRS 

with P/V valve, lb/1,000 gal.2

 GILAL = Air to liquid ratio (A/L) for the Gilbarco VRS.3

 WAAL = A/L for the Dresser Wayne VRS.4

 VAAL = A/L for a vacuum assist VRS, as reported by CARB. 

 ER = Uncontrolled displacement losses from vehicle refueling, 

grams/gal. See Equation (9). 

 

Equation (22): 

PV CE VA VA PER IU PER PV = / /. 100 0 95∗ ∗

Where: PVPER = Adjusted percentage of GDFs equipped with functioning assist 

Stage II VRS and P/V valves on UST vents. 

 CEIU = In-use control efficiency of Stage II VRS. 

 VAPER = Percentage of GDFs equipped with vacuum assist Stage II VRS. 

 VAPV = Percentage of GDFs equipped with vacuum assist Stage II VRS 

and PV valves on UST vents. 

Equation (23): 

∑

=

=

= − − 25

1

[ / *( )*(1 )* * * ] n

i

VEHADJ ER FE ORVRCE ORVRADJ TPR PVPER ORVRPI VEHWT

Where: VHEADJ = Vehicle refueling and spillage emissions in a given CY for a 

specific vehicle type utilizing ORVR canisters at an adjusted 

ORVR control efficiency, grams/gal. 

 i = Vehicle age. The vehicle age for a specific vehicle type ranges 

from one to twenty-five years, with vehicles twenty-five years 

and older grouped together. 

 ER = Uncontrolled displacement losses from vehicle refueling, 

grams/gal. See Equation (9). 

 FE = Fuel economy of vehicle, based on MYE of vehicle, miles/gal. 

 ORVRCE = Control efficiency of ORVR technology. 

 ORVRADJ = Adjusted Control efficiency of ORVR technology. 

 TPR = tampering rate for ORVR canisters. 

 

1

 CARB Preliminary Draft Test Report, “Total Hydrocarbon Emissions from Two Phase II Vacuum Assist 

Vapor Recovery Systems During Baseline Operation and Simulated Refueling of Onboard Refueling Vapor 

Recovery (ORVR) Equipped Vehicles,” June 1999. 

2

 Ref. 1 

3

 Ref. 1 

4

 Ref. 1 
 PVPER = Adjusted percentage of GDFs equipped with assist Stage II VRS 

and P/V valves on UST vents. 

 ORVRPI = ORVR phase-in rate, based on MYE of vehicle. 

 VEHWT = Weighted fractional average of the number of VMT/day in a 

given CY for a specific vehicle type of a given age in relation to 

the total VMT/day in a given CY for all vehicle types of all ages. 

See Equation (5). 

E. Definition (d) 

The following equations in conjunction with Equations (2), (3), (4), (10), (11) and 

(12) were used to determine a widespread use date for definition (d): 

Equation (24): 

∑ =

= j vehicletypeGASORVR _ PER [ ORVRGAS _ PER *GU]/ GUT

Where: 

 GASORVR_PER = Percentage of gasoline dispensed to ORVR-equipped vehicles in 

a given CY. 

 ORVRGAS_PER = Percentage of vehicle fleet equipped with ORVR, gasoline basis. 

 GU = Gasoline usage in a given CY for a specific vehicle type, gal/day. 

See Equation (11). 

GUT = Total gasoline usage for a given CY for all vehicle types, 

 gal/day. See Equation (12). 
Equation (25): 

ORVR ORVR VEHWT AFE FE n

i

GAS PER PI * * /

25

1

_ ∑

=

=

=

Where: 

 ORVRGAS_PER = Percentage of vehicle fleet equipped with ORVR, gasoline basis. 

 i = Vehicle age. The vehicle age for a specific vehicle type ranges 

from one to twenty-five years, with vehicles twenty-five years 

and older grouped together. 

 ORVRPI = ORVR phase-in rate, based on MYE of vehicle. 

 VEHWT = Weighted fractional average of the number of VMT/day in a 

given CY for a specific vehicle type of a given age in relation to 

the total VMT/day in a given CY for all vehicle types of all ages. 

See Equation (3). 

 AFE = Average fuel economy for a specific vehicle type in a given CY, 

miles/gal. See Equation (10). 

 FE = Fuel economy of vehicle, based on MYE of the vehicle, 

miles/gal. 
 Appendix C 

Widespread Use Results for NESCAUM States

1
VERMONT

02468

101214161820

2001 2006 2011 2016 2021 2026

Emissions (tons/summer day)

0%10%20%30%40%50%60%70%80%90%100%

% Penetration

Emissions if only were in place, witEmissions with onrequirements, withEmissions with Stincluding "incompemissions" of 0.86 Vacuum Assist Emissions with Stwithout "excess e% ORVR Penetradefinition% ORVR Penetradefinition% ORVR Penetradefinition

"Widespread use" date 

under option (c)

"Widespread use" date under option (c2)

2
TOTAL REFUELING EMISSIONS - VERMONT

Tons Per

Summer Day

Calendar 

Year

Stage II 

Controls 

Only

ORVR 

Only

Stage II with 

ORVR, No 

Incompatibility

Stage II with 

ORVR, 

Incompatibility

% Decrease 

from 

Uncontrolled 

Emissions

Stage II 

Controls 

Only

ORVR 

Only

Stage II with 

ORVR, No 

Incompatibility

Stage II with 

ORVR, 

Incompatibility Excess Emissions

Estimated in 

Periodic 

Inventory g/gal tpsd

Vehicles < 

10,000 lb 

GVWR

All Gas 

Vehicles

Vehicles 

< 10,000 

lb 

GVWR

All Gas 

Vehicles

2001 1.519 3.094 1.349 1.377 61% 1.57 3.19 1.39 1.42 0.03 0.902 0.93 16% 16% 13% 13% 

2002 1.519 2.899 1.272 1.313 63% 1.59 3.03 1.33 1.37 0.04 1996 5.93 0.846 0.88 22% 22% 19% 19% 

2003 1.519 2.684 1.188 1.243 65% 1.61 2.84 1.26 1.31 0.06 0.795 0.84 30% 29% 26% 25% 

2004 1.519 2.453 1.097 1.167 67% 1.56 2.52 1.13 1.20 0.07 0.734 0.75 37% 37% 33% 32% 

2005 1.520 2.195 0.996 1.083 69% 1.65 2.39 1.08 1.18 0.09 0.669 0.73 45% 44% 41% 40% 

2006 1.520 1.926 0.890 0.994 72% 1.67 2.12 0.98 1.09 0.11 0.596 0.66 53% 52% 50% 48% 

2007 1.520 1.676 0.792 0.912 74% 1.69 1.87 0.88 1.02 0.13 0.533 0.59 60% 59% 57% 56% 

2008 1.520 1.454 0.704 0.839 76% 1.71 1.64 0.79 0.95 0.15 0.483 0.54 67% 66% 64% 63% 

2009 1.520 1.258 0.627 0.775 78% 1.71 1.42 0.71 0.87 0.17 0.441 0.50 73% 72% 70% 68% 

2010 1.520 1.086 0.560 0.719 80% 1.76 1.25 0.65 0.83 0.18 0.407 0.47 78% 77% 75% 74% 

2011 1.520 0.942 0.503 0.672 81% 1.78 1.10 0.59 0.78 0.20 82% 81% 80% 78% 

2012 1.520 0.823 0.456 0.632 82% 1.78 0.97 0.54 0.74 0.21 85% 84% 83% 82% 

2013 1.520 0.724 0.417 0.600 83% 1.82 0.87 0.50 0.72 0.22 88% 87% 87% 85% 

2014 1.520 0.644 0.386 0.574 84% 1.84 0.78 0.47 0.69 0.23 91% 89% 89% 87% 

2015 1.520 0.579 0.360 0.552 84% 1.86 0.71 0.44 0.68 0.23 92% 91% 91% 89% 

2016 1.520 0.527 0.340 0.535 85% 1.88 0.65 0.42 0.66 0.24 94% 92% 93% 91% 

2017 1.520 0.485 0.324 0.522 85% 1.90 0.61 0.40 0.65 0.25 95% 94% 94% 92% 

2018 1.520 0.452 0.311 0.511 86% 1.92 0.57 0.39 0.65 0.25 96% 94% 95% 93% 

2019 1.520 0.426 0.300 0.502 86% 1.94 0.54 0.38 0.64 0.26 96% 95% 96% 94% 

2020 1.520 0.405 0.292 0.495 86% 1.96 0.52 0.38 0.64 0.26 97% 96% 96% 94% 

2021 1.520 0.386 0.285 0.489 86% 1.98 0.50 0.37 0.64 0.27 98% 96% 97% 95% 

2022 1.520 0.369 0.278 0.484 86% 2.00 0.49 0.37 0.64 0.27 98% 97% 97% 95% 

2023 1.520 0.354 0.272 0.479 86% 2.02 0.47 0.36 0.64 0.28 98% 97% 98% 96% 

2024 1.520 0.343 0.268 0.475 87% 2.05 0.46 0.36 0.64 0.28 99% 97% 98% 96% 

2025 1.520 0.330 0.263 0.471 87% 2.07 0.45 0.36 0.64 0.28 99% 98% 99% 96% 

2026 1.520 0.319 0.258 0.467 87% 2.09 0.44 0.35 0.64 0.29 99% 98% 99% 97% 

2027 1.520 0.311 0.255 0.465 87% 2.11 0.43 0.35 0.64 0.29 99% 98% 99% 97% 

2028 1.520 0.301 0.251 0.461 87% 2.13 0.42 0.35 0.65 0.29 100% 98% 100% 97% 

2029 1.520 0.290 0.247 0.458 87% 2.15 0.41 0.35 0.65 0.30 100% 98% 100% 98% 

2030 1.520 0.286 0.245 0.456 87% 2.17 0.41 0.35 0.65 0.30 100% 99% 100% 98% 

0.85714286

ORVR Penetra

Grams Emitted Per Gallon Gasoline Tons Per Summer Day Environ Report VMT Basis Fuel Usage Basis 

VT Algorithm3.xls, Emissions 

3
NH Chart

Page 1

NEW HAMPSHIRE

02468

101214161820

2001 2006 2011 2016 2021 2026

Emissions (tons/summer day)

0%10%20%30%40%50%60%70%80%90%100%

% Penetration

Emissions if only in place, without Emissions with orequirements, wiEmissions with Sincluding "excess lb/1000 gal for VEmissions with Swithout "excess e% ORVR Penetrdefinition% ORVR Penetrdefinition

"Widespread use" date under option (c)

"Widespread use" date under option (c2)

4
TOTAL REFUELING EMISSIONS - NEW HAMPSHIRE

Tons Per

Summer Day

Calendar 

Year

Stage II 

Controls 

Only

ORVR 

Only

Stage II with 

ORVR, No 

Incompatibility

Stage II with 

ORVR, 

Incompatibility

% Decrease 

from 

Uncontrolled 

Emissions

Stage II 

Controls 

Only

ORVR 

Only

Stage II with 

ORVR, No 

Incompatibility

Stage II with 

ORVR, 

Incompatibility Excess Emissions

Estimated in 

Periodic 

Inventory g/gal tpsd

Vehicles < 

10,000 lb 

GVWR

All Gas 

Vehicles

Vehicles 

< 10,000 

lb 

GVWR

All Gas 

Vehicles

2001 1.149 2.604 1.020 1.044 65% 2.41 5.46 2.14 2.19 0.05 0.902 1.89 16% 16% 14% 14% 2002 1.149 2.416 0.956 0.992 67% 2.46 5.17 2.05 2.12 0.08 1996 5.93 0.846 1.81 23% 23% 21% 20% 

2003 1.164 2.236 0.895 0.945 69% 2.54 4.88 1.95 2.06 0.11 0.795 1.74 32% 31% 29% 28% 2004 1.164 1.998 0.814 0.879 71% 2.59 4.45 1.81 1.96 0.15 0.734 1.63 41% 40% 37% 37% 2005 1.164 1.752 0.731 0.811 73% 2.64 3.98 1.66 1.84 0.18 0.669 1.52 49% 49% 46% 45% 2006 1.164 1.505 0.647 0.743 76% 2.70 3.49 1.50 1.72 0.22 0.596 1.38 58% 57% 55% 54% 2007 1.164 1.299 0.578 0.687 77% 2.75 3.07 1.36 1.62 0.26 0.533 1.26 65% 64% 62% 61% 2008 1.164 1.099 0.510 0.632 79% 2.81 2.65 1.23 1.52 0.29 0.483 1.16 71% 71% 69% 68% 2009 1.165 0.951 0.460 0.591 81% 2.86 2.34 1.13 1.45 0.32 0.441 1.08 76% 76% 75% 74% 2010 1.165 0.817 0.415 0.554 82% 2.92 2.05 1.04 1.39 0.35 0.407 1.02 81% 80% 80% 78% 2011 1.164 0.695 0.373 0.520 83% 2.98 1.78 0.95 1.33 0.38 85% 84% 84% 83% 2012 1.165 0.618 0.347 0.499 84% 3.04 1.61 0.91 1.30 0.40 88% 87% 87% 85% 2013 1.164 0.538 0.320 0.477 84% 3.10 1.43 0.85 1.27 0.42 91% 90% 90% 88% 2014 1.165 0.481 0.301 0.461 85% 3.16 1.30 0.82 1.25 0.44 93% 92% 92% 90% 2015 1.165 0.434 0.285 0.449 85% 3.22 1.20 0.79 1.24 0.45 94% 93% 93% 92% 2016 1.165 0.395 0.272 0.438 86% 3.29 1.12 0.77 1.24 0.47 96% 95% 95% 93% 2017 1.165 0.368 0.263 0.430 86% 3.36 1.06 0.76 1.24 0.48 96% 96% 96% 94% 2018 1.165 0.338 0.253 0.422 86% 3.42 0.99 0.74 1.24 0.50 97% 96% 97% 95% 2019 1.165 0.319 0.246 0.417 86% 3.49 0.96 0.74 1.25 0.51 98% 97% 97% 96% 2020 1.165 0.304 0.241 0.413 86% 3.56 0.93 0.74 1.26 0.52 98% 97% 98% 96% 2021 1.165 0.293 0.238 0.410 87% 3.63 0.91 0.74 1.28 0.54 99% 98% 98% 97% 2022 1.165 0.282 0.234 0.407 87% 3.70 0.90 0.74 1.29 0.55 99% 98% 99% 97% 2023 1.165 0.273 0.231 0.404 87% 3.78 0.89 0.75 1.31 0.56 99% 98% 99% 98% 2024 1.165 0.269 0.229 0.403 87% 3.85 0.89 0.76 1.33 0.58 99% 98% 99% 98% 2025 1.165 0.265 0.228 0.402 87% 3.93 0.89 0.77 1.36 0.59 100% 99% 99% 98% 2026 1.165 0.261 0.227 0.401 87% 4.01 0.90 0.78 1.38 0.60 100% 99% 100% 98% 2027 1.165 0.258 0.226 0.400 87% 4.09 0.91 0.79 1.41 0.61 100% 99% 100% 98% 2028 1.165 0.255 0.225 0.399 87% 4.17 0.91 0.80 1.43 0.63 100% 99% 100% 98% 2029 1.165 0.250 0.223 0.398 87% 4.26 0.91 0.82 1.45 0.64 100% 99% 100% 98% 2030 1.165 0.249 0.223 0.398 87% 4.34 0.93 0.83 1.48 0.65 100% 99% 100% 98% 

0.85714286

ORVR Penetra

Grams Emitted Per Gallon Gasoline Tons Per Summer Day Environ Report VMT Basis Fuel Usage Basis 

NH Algorithm3.xls, Emissions 

5
MA Chart 

Page 1

MASSACHUSETTS

02468

101214161820

2001 2006 2011 2016 2021 2026

Emissions (tons/summer day)

0%10%20%30%40%50%60%70%80%90%100%

% Penetration

Emissions if only in place, without OEmissions with onrequirements, witEmissions with Stincluding "excess lb/1000 gal for VaEmissions with Stwithout "excess e% ORVR Penetradefinition% ORVR Penetradefinition

"Widespread use" date under option (c)

"Widespread use" date under option 

( 2)

6
TOTAL REFUELING EMISSIONS -MASSACHUSETTS

Tons Per

Summer Day

Calendar 

Year

Stage II 

Controls 

Only

ORVR 

Only

Stage II with 

ORVR, No 

Incompatibility

Stage II with 

ORVR, 

Incompatibility

% Decrease 

from 

Uncontrolled 

Emissions

Stage II 

Controls 

Only

ORVR 

Only

Stage II with 

ORVR, No 

Incompatibility

Stage II with 

ORVR, 

Incompatibility Excess Emissions

Estimated in 

Periodic 

Inventory g/gal tpsd

Vehicles < 

10,000 lb 

GVWR

All Gas 

Vehicles

Vehicles 

< 10,000 

lb 

GVWR

All Gas 

Vehicles

2001 0.682 2.307 0.617 0.635 76% 5.92 20.02 5.35 5.51 0.16 0.902 7.83 16% 16% 14% 14% 2002 0.682 2.147 0.585 0.613 77% 6.01 18.93 5.16 5.41 0.25 1996 5.93 0.846 7.46 24% 23% 21% 20% 

2003 0.689 2.005 0.556 0.594 78% 6.18 17.97 4.98 5.33 0.34 0.795 7.13 32% 31% 28% 27% 2004 0.690 1.813 0.518 0.567 79% 6.28 16.51 4.72 5.17 0.45 0.734 6.68 40% 40% 36% 35% 2005 0.690 1.599 0.476 0.537 80% 6.38 14.78 4.40 4.97 0.57 0.669 6.19 49% 48% 45% 44% 2006 0.690 1.373 0.432 0.506 81% 6.48 12.90 4.06 4.75 0.69 0.596 5.60 57% 57% 54% 53% 2007 0.690 1.166 0.391 0.477 82% 6.57 11.12 3.73 4.55 0.82 0.533 5.08 65% 64% 62% 61% 2008 0.690 0.982 0.355 0.451 83% 6.67 9.50 3.44 4.36 0.93 0.483 4.67 72% 71% 70% 68% 2009 0.690 0.823 0.324 0.429 84% 6.77 8.08 3.18 4.21 1.03 0.441 4.33 78% 77% 77% 75% 2010 0.690 0.687 0.297 0.410 85% 6.87 6.84 2.96 4.08 1.12 0.407 4.05 83% 82% 82% 80% 2011 0.690 0.578 0.276 0.395 85% 6.97 5.84 2.79 3.99 1.20 88% 86% 86% 85% 2012 0.690 0.494 0.259 0.383 86% 7.07 5.06 2.66 3.92 1.27 91% 90% 90% 88% 2013 0.690 0.428 0.246 0.374 86% 7.17 4.45 2.56 3.88 1.32 93% 92% 93% 91% 2014 0.690 0.378 0.237 0.367 86% 7.27 3.98 2.49 3.86 1.37 95% 94% 95% 93% 2015 0.690 0.342 0.230 0.362 87% 7.36 3.65 2.45 3.86 1.41 96% 95% 96% 94% 2016 0.690 0.317 0.225 0.358 87% 7.46 3.43 2.43 3.88 1.44 97% 96% 97% 95% 2017 0.690 0.299 0.221 0.356 87% 7.56 3.27 2.42 3.90 1.48 98% 97% 98% 96% 2018 0.690 0.286 0.219 0.354 87% 7.66 3.17 2.43 3.93 1.50 98% 97% 98% 96% 2019 0.690 0.275 0.217 0.352 87% 7.76 3.09 2.44 3.96 1.53 99% 98% 99% 97% 2020 0.690 0.267 0.215 0.351 87% 7.86 3.04 2.45 4.00 1.55 99% 98% 99% 97% 2021 0.690 0.260 0.214 0.350 87% 7.95 3.00 2.46 4.04 1.58 99% 98% 99% 97% 2022 0.690 0.253 0.212 0.349 87% 8.05 2.96 2.48 4.08 1.60 100% 98% 99% 98% 2023 0.690 0.249 0.211 0.349 87% 8.15 2.94 2.50 4.12 1.62 100% 98% 100% 98% 2024 0.690 0.246 0.211 0.348 87% 8.24 2.94 2.52 4.16 1.64 100% 99% 100% 98% 2025 0.690 0.242 0.210 0.348 87% 8.34 2.92 2.54 4.20 1.67 100% 99% 100% 98% 2026 0.690 0.241 0.210 0.348 87% 8.43 2.95 2.57 4.25 1.68 100% 99% 100% 98% 2027 0.690 0.241 0.210 0.348 87% 8.53 2.98 2.59 4.30 1.70 100% 99% 100% 98% 2028 0.690 0.240 0.210 0.347 87% 8.62 3.00 2.62 4.34 1.72 100% 99% 100% 98% 2029 0.690 0.239 0.209 0.347 87% 8.71 3.01 2.64 4.39 1.74 100% 99% 100% 98% 2030 0.690 0.238 0.209 0.347 87% 8.81 3.04 2.67 4.43 1.76 100% 99% 100% 98% 

0.85714286

ORVR Penetra

Grams Emitted Per Gallon Gasoline Tons Per Summer Day Environ Report VMT Basis Fuel Usage Basis 

MA Algorithm3.xls, Emissions 

7