Onboard Refueling Vapor Recovery Systems 

Analysis of Widespread Use

By Eric Skelton and Lisa Rector 

NESCAUM 

August 20, 2007 

Introduction

Beginning in the mid-1970s as states began developing ozone attainment plans in 

response to requirements of the federal Clean Air Act (CAA), gasoline refueling was 

identified as a candidate area source category for controlling volatile organic 

compound (VOC)1 emissions. Considering that millions of gallons of gasoline were 

dispensed daily into motor vehicles, it was readily apparent that gasoline refueling 

was one of the most significant VOC area source categories and therefore one of the 

highest priority categories to be controlled as part of an overall ozone attainment 

strategy. 

Gasoline is a relatively volatile liquid that readily vaporizes to saturate air in a 

confined space, such as the space above the liquid level in a motor vehicle fuel tank. 

When the fuel tank is subsequently refilled with liquid gasoline, this air-vapor 

mixture is displaced out of the tank and through the fill pipe. Without some means of 

capture, the vapors escape to the ambient air, ultimately contributing to 

photochemical processes that form ozone and other oxidants. 

Early on, states and the U.S. Environmental Protection Agency (EPA) identified two 

basic conceptual approaches to capturing gasoline vapors. The first approach (Stage 

II Vapor Recovery, or “Stage II”) was first implemented in the late 1970s and 

ultimately became a requirement under CAA § 182(b)(3) for areas classified as 

moderate, serious, severe, and extreme ozone nonattainment areas. Stage II allows 

the vapors to continue to pass through the motor vehicle fuel tank fill pipe but retains 

the vapors at the gasoline service station, capturing them at the interface between the 

fill pipe and the dispensing nozzle. 

In a typical Stage II installation, a flexible rubber bellows surrounds the nozzle spout, 

forming a partial seal around the lip of the fill pipe. The vapors are forced by 

displacement through a chamber in the nozzle, into a second hose or into the annular 

space between dual hoses, and into underground piping connected to the vapor space 

in the underground storage tank. Once in the underground tank, the vapors remain in 

a gaseous state within the tank’s head space where they may partially convert to a 

liquid phase as the tank re-establishes equilibrium between liquid and vapor phases, 

or partially escape through the tank vent or leaks in the system. Ultimately, most of 

the vapors are displaced out of the underground tank into a cargo tank (Stage I Vapor 

 

1

 In the atmosphere, VOCs along with nitrogen oxides in the presence of sunlight and heat promote formation of 

ozone and other photochemical oxidants. Thus, attainment strategies for reducing tropospheric ozone levels focus 

on reducing emissions of VOCs, nitrogen oxides, or a combination of the two. 
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Recovery) and transported to a gasoline terminal, either to be condensed into liquid or thermally 

destroyed. According to data compiled in 2006 by EPA’s Office of Transportation and Air 

Quality and illustrated in Figure 1 below, there are 27 states and the District of Columbia 

involving 275 counties nationally that have implemented various levels of Stage II programs. In 

some states, Stage II programs are required state-wide. Other states limit the coverage of their 

Stage II programs to their ozone nonattainment areas. 

Figure 1 – Stage II Vapor Recovery Areas – 275 Counties

The second approach (Onboard Refueling Vapor Recovery, or “ORVR”), also required under 

CAA § 202(a)(6), began with certain 1998 model year new gasoline-powered light duty motor 

vehicles (passenger cars and light trucks), with full phase in by model year 2006 for other classes 

of gasoline powered motor vehicles.2

 The approach involves creating a mechanical or liquid seal 

around the dispensing nozzle, redirecting the vapors away from the fuel tank fill pipe, and 

forcing the vapor stream to pass though a canister filled with activated carbon. The vapors are 

then adsorbed onto the carbon for temporary storage. Upon engine restart, air is pulled through 

the canister to purge the vapors from the carbon and route them to the engine where they are 

combusted. Approved Stage II and ORVR systems both are certified to be 95 percent efficient in 

capturing VOC emissions from refueling gasoline powered motor vehicles. In theory, the choice 

of one system type versus the other is emissions neutral. In practice, there are a number of 

factors that affect the efficiency of each system type. 

The decision by Congress to require new motor vehicles to be equipped at some point with 

ORVR was also a decision ultimately to cease requiring Stage II at gasoline service stations. As 

increasing numbers of ORVR-equipped motor vehicles replace the aging fleet of motor vehicles 

without ORVR, there is a continually diminishing mass of displaced gasoline vapors available 

for capture by Stage II. Using Massachusetts as an example, Figure 2 illustrates how ORVR as a 

 

2

 The ORVR requirements apply to light-duty vehicles, light-duty trucks, medium-duty passenger vehicles, and 

complete heavy-duty vehicles. For specific phase-in dates and definitions of vehicle classes, see Appendix A. 
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stand-alone technology ultimately achieves significantly greater emissions reductions compared 

to a hypothetical scenario whereby Stage II is maintained as a stand-alone technology for 

capturing gasoline refueling vapors (i.e., ORVR never implemented). If Stage II were the sole 

program for controlling emissions from gasoline refueling, emissions would continue to increase 

as gasoline throughput increases. In contrast, the emissions benefits of ORVR as the sole 

program will extend out until virtually all light-duty gasoline vehicles (as defined in Appendix 

A) are ORVR equipped. 

Figure 2 – Emissions from ORVR & Stage II as Stand-Alone Programs (Massachusetts) 

0

2

4

6

8

10

12

14

16

18

20

2001 2006 2011 2016 2021 2026

Emissions (tons/summer day) . 

Emissions if only Stage II controls were in place, without ORVR

Emissions with only ORVR requirements, without Stage II controls

Most Stage II programs will reach a point where the continually diminishing emissions benefit 

will no longer justify the cost of installing new systems or maintaining existing ones. In fact, 

there is an eventual emissions disbenefit associated with continuing to employ many of the Stage 

II systems. CAA § 202(a)(6) authorizes the EPA Administrator to waive the Stage II 

requirements for areas classified as serious, severe, or extreme when the Administrator 

determines that ORVR systems are in “widespread use” throughout the motor vehicle fleet.3 The 

CAA appears to give the Administrator considerable discretion in defining widespread use. 

 

3

 CAA § 202(a)(6) also states that Stage II controls no longer apply to moderate ozone nonattainment areas after 

EPA promulgates regulations implementing ORVR. These regulations were promulgated on April 16, 1994 (59 FR 

16262). 
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However, for purposes of this analysis, it is assumed pursuant to the anti-backsliding 

requirements in CAA § 110(l) that EPA would not authorize a state to discontinue a Stage II 

program if the result would be to worsen air quality in the state or nonattainment area(s) within a 

state where the Stage II equipment is installed. 

Using this approach, a strong argument can be made that ORVR is in “widespread use” when 

ORVR by itself achieves the same or a better emissions benefit compared to maintaining Stage II 

requirements in the state or applicable nonattainment areas, as ORVR-equipped vehicles phase 

into the fleet. When states are able to project the year in which ORVR by itself achieves the 

same or a better emissions benefit as compared to maintaining Stage II requirements and 

subsequently submit amendments to their ozone attainment or maintenance plans to discontinue 

Stage II programs, such amendments should meet the no-backsliding test. 

Stage II Programs in the Ozone Transport Region (OTR)

The OTR was created under CAA § 184 to address regional transport of ozone and ozone 

precursors in the northeastern U.S.4 Among other provisions, § 184(b)(1) prescribed specific 

control requirements5 to be incorporated into ozone implementation plans for states in the OTR. 

Additionally, in accordance with § 184(b)(2), all areas in the OTR, regardless of their ozone 

attainment status, had to adopt Stage II or alternative measures capable of achieving comparable 

emissions reductions. The CAA required EPA to complete a study identifying such control 

measures.6 States with ozone nonattainment classifications of serious and above had no other 

option but to adopt and implement Stage II programs in these areas. However, areas in the OTR 

with classifications of moderate or below had the option of adopting comparable measures. 

States in the OTR that are now contemplating discontinuing Stage II programs at some future 

date face an additional hurdle of addressing the comparable measures requirement in § 184(b)(2). 

 

Factors Affecting the ORVR Emissions Benefit

There are many factors affecting when the state-wide or nonattainment area-wide collective 

emissions benefits achieved with ORVR become superior to the benefits of a Stage II program 

and therefore when states may discontinue their Stage II programs without adversely affecting 

air quality. We discuss the principal factors in the following paragraphs. 

In-Use Efficiency of Stage II Programs. Although Stage II programs have been important 

components of the suite of controls for ozone attainment purposes, they do not perfectly capture 

and control gasoline vapors. The in-use efficiency of Stage II as a control technology or strategy 

varies from station to station and locality to locality. These variations affect emissions and 

therefore affect when ORVR becomes the better choice as a stand-alone state-wide or area-wide 

control strategy. Areas with very effective Stage II programs will continue to benefit from a 

combination of Stage II and ORVR for several years beyond the point at which areas with less 

effective Stage II programs determine that a stand-alone ORVR program achieves a better result. 

 

4

 The OTR covers the entire states of Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, 

New Jersey, New York, Pennsylvania, Rhode Island, and Vermont, along with the District of Columbia consolidated 

metropolitan statistical area (CMSA), which includes a portion of northern Virginia. 

5

 The specific requirements were for enhanced vehicle inspection and maintenance programs and reasonably 

available control technology for all VOC sources covered by control techniques guidelines, 

6

 Stage II Comparability Study for the Northeast Ozone Transport Region, EPA, January 1995. 
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The following is a summary of the primary factors which influence the effectiveness of Stage II 

programs. 

1. Rule penetration. Typically, Stage II is not required at every gasoline service station in every 

state. Many states limit the application of Stage II to ozone nonattainment and maintenance 

areas as part of their federally approved plans. Within these areas, Stage II often is required only 

at commercial service stations with larger underground storage tanks and/or with annual or 

monthly average gasoline throughputs above specified thresholds. Decreased rule penetration 

within the geographical area where Stage II is required translates into more emissions from Stage 

II equipment and a nearer date by which ORVR is determined to be the superior stand-alone 

strategy. 

2. Rule effectiveness. Stage II systems, in particular the dispensing nozzles and hoses, require 

regular and consistent maintenance to optimize emission reductions. The best maintained 

systems typically are inspected regularly by station personnel who are able to identify 

maintenance problems (e.g., damaged bellows or hoses) and expeditiously complete the 

necessary repairs. The certainty of frequent inspections by state and local regulatory personnel 

tends to deter postponement of critical repairs by station personnel. As is the case with rule 

penetration, decreased rule effectiveness translates into more emissions from Stage II and a 

nearer date for a determination for reliance solely on ORVR. 

In its Stage II Technical Guidance,7 EPA developed in-use efficiency factors for Stage II 

programs based on a combination of exemption levels (rule penetration) and inspection 

frequency (rule effectiveness). Table 1 lists the various efficiency factors. The table shows, 

among other things, that in-use efficiency decreases significantly from certification levels when 

the inspection frequency is minimal. In addition, the table shows that even though individual 

Stage II systems are certified to be 95 percent efficient, an overall Stage II program likely will 

not control 95 percent of an affected area’s gasoline refueling emissions. 

Table 1 – Program In-Use Efficiency Factors (% Efficiency)

Inspection 

Frequency 

Minimal Annual Semiannual Certification 

Exemption 

Level (gal/mo) 

None 62 86 92 95 

2000 61 84 90 93 

10,000 60 84 89 92 

10,000 & 50,000 56 77 83 86 

3. System integrity. The plumbing connecting the gasoline dispenser to the underground storage 

tank is intended to provide an unrestricted and vapor-tight passage for collecting gasoline vapors. 

Likewise, other tank plumbing fixtures, such as vent pipes, pressure vacuum valves, fill pipes, 

and Stage I Vapor Recovery Systems, are intended to be installed and maintained in a vapor-tight 

condition and to function properly at all times. In reality, connections and fixtures do not always 

 

7

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

Dispensing Facilities, EPA-450/3-91-022a, November 1991. 
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function properly or are not always vapor-tight. Additionally, if the plumbing from the dispenser 

does not properly slope all the way to the underground tank, condensed liquid may collect in low 

spots, partially or completely obstructing vapor return lines, and creating back-pressure in the 

system. Pressure vacuum valves also may not close completely after venting or may stick in a 

closed position, forcing pressure to be relieved at weak points in the system. Cargo tank drivers 

may fail to properly connect vapor return hoses to the Stage I system during tank filling. These 

are the types of factors, tied to inspection frequency, that contribute to the fugitive emissions of 

gasoline vapors, thereby adversely affecting the efficiency of Stage II , relative to ORVR. 

4. System type. There are two general types of Stage II systems; balance and vacuum-assist. 

Typically, both types are in use in any given state program, and the propensity to favor one 

system type over another varies by state. The balance system is the simpler of the two. It relies 

on the draw-down of gasoline from the underground storage tank during refueling to create a 

slight vacuum in the vapor return lines that is sufficient to draw most of the vapors dispensed 

from the motor vehicle fuel tank into the vapor return system. The dispensing nozzle bellows 

and the seal it creates against the lip of the motor vehicle fill pipe help to maintain the slight 

vacuum necessary to “balance” the volume of gasoline vapors displaced from the motor vehicle 

fuel tank against the volume of liquid extracted from the underground tank. 

The vacuum-assist type of system employs a mechanical vacuum pump or a venturi8

 to actively 

draw the displaced vapors into the Stage II system. Typically, the degree of vacuum is set by 

adjusting the volume of air drawn into the Stage II system against the volume of liquid 

dispensed. This setting is known as the Air-to-Liquid Ratio (A/L). If the A/L is greater than 1, a 

greater volume of air is drawn into the Stage II system, relative to the volume of liquid drawn 

from the underground storage tank. Drawing excess air increases the capture of vapors displaced 

out of the motor vehicle fill pipe. These systems often are more acceptable to consumers 

because the nozzles look and operate more like those from the pre-Stage II era. They are 

equipped with less bulky reduced-tension bellows or may not be required to have a bellows. 

A higher A/L ratio is beneficial only to a point. If too much excess air enters the system, the 

head space pressure in the underground storage tank may increase. At some point, this pressure 

may have to be relieved by opening the pressure vacuum valve, allowing vapors to escape to the 

ambient air. Vapors may also leak to soil, groundwater, and the atmosphere through plumbing 

connections that are not leak resistant to pressurization. In addition, excess air introduced into 

the headspace of an underground storage tank upsets the equilibrium at the interface between gas 

and liquid. To re-establish equilibrium, more liquid gasoline must convert to a vapor phase and 

occupy the tank head space. This phenomenon, known as vapor growth, increases pressurization 

of the Stage II system and increases the mass of vapor that is released through the pressure 

vacuum valve or via system leaks, or requires collection by the Stage I system. In theory, greater 

vacuum at the nozzle, resulting from a higher A/L ratio, also may cause more liquid gasoline, 

otherwise destined for the motor vehicle fuel tank, to vaporize inside the fill pipe and be captured 

by the Stage II system. 

 

8

 A venturi is a tube with tapered constriction in the middle, designed to cause an increase in the velocity of flow of 

a fluid and a corresponding decrease in fluid pressure to create a vacuum. 
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The increased vapor collection efficiency of vacuum-assisted Stage II systems, partially offset by 

the effects described above of excess air on leakage and vapor growth, affects overall emissions 

from Stage II and thereby affects when stand-alone ORVR becomes the more effective choice 

for controlling emissions. Vacuum-assist Stage II systems also exhibit certain incompatibility 

problems with ORVR. This will be discussed later. 

Motor Vehicle Fleet Characteristics. The overall attributes of a motor vehicle fleet, within a 

state or nonattainment area that utilizes Stage II systems, likewise have a significant effect on 

refueling emissions. The following is a summary of the primary fleet characteristics which will 

influence state decisions regarding when to discontinue their Stage II programs. 

1. Fleet turnover. At some point, as older vehicles are retired from the fleet and replaced by 

newer vehicles, virtually all light-duty motor vehicles will be ORVR-equipped. However, the 

fleet turnover rate varies from state to state, depending on such factors as personal disposable 

income, weather, road conditions, and accident rates. As the analysis illustrates later in this 

report, it is unnecessary for states to wait until 100 percent of the vehicle fleet is ORVRequipped before discontinuing Stage II programs. However, states with a higher fleet turnover 

rate are likely to see stand-alone ORVR effectiveness surpass Stage II at an earlier date, 

compared to states with a relatively lower turnover rate. 

2. Vehicle type. Differences in consumer preferences for vehicle types also affect ORVR 

penetration and overall control of refueling emissions by Stage II. ORVR was first introduced in 

lighter light-duty new gasoline vehicles and phased in over time into the fleet of heavier lightduty new vehicles (see Appendix A). If there is a preference by consumers in a particular state 

for purchasing heavier vehicles, the percentage of ORVR-equipped vehicles registered in that 

state will be lower9

 compared to a state where the preference is for lighter vehicles. The 

resulting lower ORVR penetration rate tends to postpone the date by which ORVR surpasses 

Stage II. 

3. Fuel efficiency. There is a contributing factor to be considered that is associated with a higher 

percentage of heavier vehicles (e.g., light-duty trucks) in the fleet and their concomitant lower 

fuel efficiency. Consider two hypothetical fleets; one heavier, with an average fuel efficiency of 

15 miles per gallon (mpg), and the other considerably lighter with an efficiency of 30 mpg. The 

heavier fleet must consume 100,000 gallons of fuel to travel a collective 1.5 million miles. In 

contrast, the lighter, more fuel efficient fleet consumes only 50,000 gallons of fuel to travel the 

same distance. Over the span of time in which it takes to travel the 1.5 million miles, the heavier 

fleet, upon refueling, displaces 100,000 gallons of a saturated mixture of air and gasoline vapors 

and the lighter fleet only 50,000 gallons. Assuming near identical degrees of saturation in the 

displaced air/fuel mixtures between the two fleets, the heavier fleet displaces twice the mass of 

gasoline vapor per distance traveled compared to the lighter fleet. Thus, having a higher 

percentage of heavier vehicles in a fleet will result in more emissions from gasoline refueling, 

both from ORVR and Stage II. Depending on the comparative in-use efficiency between ORVR 

and Stage II, fleet-wide fuel efficiency could have the effect of either moving forward or 

postponing the date by which ORVR surpasses Stage II. 

 

9

 This heavier vehicle effect began to diminish in model year 2006 when ORVR was required for 100 percent of 

new heavy light-duty trucks, medium-duty passenger vehicles, and complete heavy-duty vehicles. 
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ORVR Widespread Use Analysis 

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4. Vehicle miles traveled (VMT). VMT differences from state-to-state depend on a number of 

factors, including population, average commute distance to work, availability of transportation 

alternatives, personal disposable income, severity of traffic congestion, and personal preference. 

Higher state-wide VMT means more fuel is dispensed and consumed and therefore more 

emissions per unit of time from gasoline refueling and Stage II systems. Similar to the fuel 

efficiency concept described above, the effect of higher VMT on refueling emissions will affect 

the date for moving to a stand-alone ORVR program. 

Other Factors Affecting Refueling Emissions. In addition to Stage II and motor vehicle fleet 

characteristics, other miscellaneous factors affect VOC concentrations in gasoline vapors and 

affect refueling emissions. Some of the more significant factors are discussed below. 

1. Gasoline volatility. Gasoline is a complex mixture of organic compounds, including lighter 

species that readily evaporate. The propensity for gasoline to evaporate from motor vehicles and 

refueling operations is a function of its Reid vapor pressure (RVP), measured in pounds per 

square inch (psi). Prior to RVP controls, typical summertime gasoline RVP in the northeast U.S. 

ranged from 10.8 to 11.7 psi. Phase I RVP controls took effect in 1989, limiting RVP to a range 

of 9.0 to 10.5 psi, with the most stringent limits applying to ozone nonattainment areas. Phase II 

RVP controls became effective in 1992, capping summertime RVP at 9.0 psi with a more 

stringent cap of 7.8 psi applying in ozone nonattainment areas. Further, reformulated gasoline 

(RFG), required in ozone nonattainment areas, typically has much lower summertime RVP 

levels, on the order of 6.8 psi. Higher RVP will tend to elevate the VOC concentration in the 

vapor stream and increase emissions from Stage II systems and from ORVR-equipped motor 

vehicles. 

2. Temperature. Gasoline volatility also is affected by temperature. On hot summer days, 

refueling emissions tend to increase both from ORVR-equipped motor vehicles and from Stage 

II systems simply because gasoline’s evaporation increases with temperature. There is an 

offsetting effect related to the difference in temperature between the cooler dispensed fuel 

temperature and the warmer motor vehicle fuel tank. As the cooler dispensed fuel enters the 

motor vehicle fuel tank, it has a condensing effect in the vapor head space, effectively reducing 

the mass of vapor to be routed to the carbon adsorber. 

Also, increased sunlight and heat, typically associated with elevated ambient temperature events, 

favor formation of tropospheric ozone and other photochemical oxidants. For these reasons, 

widespread use analyses focus on the hottest days of the summer or the days in which ozone 

levels are highest. These factors will of course vary considerably from one area to another. 

3. Refueling Activity. The activity level at gasoline service stations with high-volume throughputs 

tends to minimize the opportunity for the underground storage tanks and the Stage II system to 

establish equilibrium conditions. Consequently, pressure vacuum valves may open and vent to 

the atmosphere more frequently in response to build-up of pressure in the system. The VOC 

concentration of the vapor stream also will vary, thereby affecting the VOC emissions rate 

during the release event. 
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ORVR Widespread Use Analysis 

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Effectiveness of ORVR Systems

As previously stated, ORVR systems are certified to be 95 percent efficient in capturing VOC 

emissions during refueling operations. However, in-use efficiency is influenced by other factors, 

as described below. 

Reliability and Durability. In concept, an ORVR system is quite simple. Organic vapors are 

displaced during refueling to a sealed canister where they adsorb onto activated carbon. 

Following engine start up, air is pulled through the canister to purge the vapors, which are then 

routed to the engine and combusted. The vehicle’s On-Board Diagnostic (OBD) System 

monitors the function of critical components of the system. However, there are limited in-use 

data available on the reliability of ORVR systems, particularly systems that have been in 

operation for many years. The available data have been provided to EPA by automobile 

manufacturers. 

Figure 3 – ORVR Test Data Submitted to EPA as of April 2006 

ORVR test results

3

70

146

28

8

11

2 2 1

0

20

40

60

80

100

120

140

160

0

0-0.01

0.01-0.1

0.1-0.20.2-0.3

0.3-1

1-22-5

>5

emission rate (std 0.2)

Frequency

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Frequency

Cumulative %

Preliminary information compiled in April 2006 on 288 vehicles showed that 24 (8.8 percent of 

the total) did not meet the standard of 0.20 grams of VOC per gallon of fuel dispensed.10

 

 

10 The 0.20 gram per gallon standard is equivalent to the required 95 percent efficiency for ORVR systems. 
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However, of the vehicles that passed the test, more than 80 percent showed results that were half 

the standard or less. Therefore, although an 8.8 percent failure rate may seem high, the average 

emission rate overall was well within the standard, suggesting that the ORVR program as a 

whole achieves better than a 95 percent control efficiency. In fact, EPA’s MOBILE6 model 

assumes that ORVR systems are 98 percent efficient in controlling the portion of refueling 

emissions that does not include spillage.11 Figure 3 (above) illustrates the frequency of 

compliance with the standard for this limited data set. 

There is no information available regarding the effectiveness of OBD systems to detect an 

ORVR malfunction. Lacking sufficient data, the assumption in this analysis is that ORVR 

systems retain the same high degree of effectiveness for the life of the vehicle. 

Gasoline Spillage. Spillage of gasoline during vehicle refueling is a common event, involving 

both vehicle design and human factors. To account for spillage, EPA’s ORVR certification 

includes a requirement that any spillage occurring during the certification test is counted in the 

emission results. This requirement had the effect of discouraging use of fill pipe designs prone to 

cause spitback spillage. Each cubic centimeter of gasoline spilled weighs about 0.67 grams, so 

spillage of even a small volume of gasoline during the refill, required in the test, likely will result 

in failure to meet the 0.2 gram per gallon refueling emission standard. Based on the refueling 

emission test procedure requirement and the results of the field tests displayed in Figure 3 above, 

it seems clear that ORVR, in conjunction with fill pipe redesign, has reduced gasoline spillage. 

The emissions modeling used in the widespread use analysis accounts for the reduced spillage 

benefit by incorporating a spillage emission factor for ORVR which is one-half of that for nonORVR vehicles using conventional nozzles. 

Compatibility with Stage II Systems. As previously explained, the ORVR system minimizes or 

prevents the escape of gasoline vapors from the fill pipe of the motor vehicle fuel tank by 

directing the vapors to a canister. Thus, when an ORVR-equipped vehicle is refueled at a 

gasoline service station equipped with Stage II, there is little to no vapor to be captured and 

routed to the underground storage tank.12 If the Stage II system is a balance system, the slight 

negative pressure created during draw-down of liquid fuel in the underground tank will cause an 

equivalent volume of fresh air to be drawn into the Stage II system. This air may enter by way 

of one or more refueling nozzles that are in use at the time but for which the interface between 

the bellows and the fill pipe is imperfectly sealed. Air also may enter from leaks in the system 

plumbing or through a defective or missing vacuum vent valve. If the system is perfectly sealed, 

a slight negative pressure will be established in the head space of the underground storage tank. 

In either circumstance, the gasoline dispensing action upsets equilibrium, and liquid gasoline will 

vaporize at the liquid-vapor interface in the tank until equilibrium is re-established. 

If the Stage II system is vacuum-assisted, air in excess of the volume of gasoline dispensed is 

drawn into the system. When fueling an ORVR-equipped vehicle, this air likely contains no 

gasoline vapors. If the seal formed in the fill pipe is a liquid seal, the slight vacuum at the nozzle 

may cause some liquid gasoline to vaporize and be drawn into the Stage II system. The volume 

 

11 Frequently Asked Questions on Mobile6, EPA, January 16, 2002. 

12 This is the case regardless of whether the ORVR system is functioning properly to capture and retain the vapors in 

the canister. 
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of air entering the system in excess of the volume of gasoline dispensed creates a slight positive 

pressure within the head space of the tank. Since the newly introduced air likely contains little to 

no gasoline vapor, gasoline inside the underground storage tank converts from liquid to vapor 

phase (vapor growth) to re-establish equilibrium. Multiple fillings of ORVR-equipped vehicles 

further increase pressure in the Stage II system, causing vapors to escape though system leaks or 

causing the pressure-vacuum valve to open. Emissions created by this interaction between 

ORVR-equipped vehicles and vacuum-assisted Stage II systems are referred to as 

Incompatibility Excess Emissions (IEE). 

Table 2 – Comparison of Test Data for Determining IEE Factors13

Incompatibility Excess Emissions Factor (lbs/1000 gal) 

Test Data 

Gilbarco 

vacuum-assist 

VRS (Certified 

A/L ratio is 1.0 to 

1.2) 

Wayne-Dresser 

vacuum-assist 

VRS (Certified 

A/L ratio is 0.9 to 

1.1) 

ORVR – Vehicle 

fuel tank fill pipe 

savings 

(reduction) 

Overall 

(Gilbarco) excess 

emissions factor 

CARB TEST 

(1999) 0.86 a 0.06 a N/A 0.86 

API analysis of 

CARB IEE factor 0.78 b 0.08 b N/A 0.78 b 

API Phase 1 

Report (2004) N/A N/A 0.31 0.55 c 

API Phase 2 

Report (2004) 0.72 N/A 0.39 0.33 

aThe CARB report provides average emissions for baseline and ORVR-simulated refueling; the IEE factors were 

calculated by EPA’s contractor from these values and the percent of ORVR vehicles simulated; for the WayneDresser system, only the test with the P/V valve intact was used. 

bAPI used a linear regression of the CARB test results to determine the emission factor at 100 percent ORVR 

vehicle simulation and adjusted the factors for a lower Reid vapor pressure (assumed uncontrolled emissions of 7.6 

lbs/1000 gal versus 8.4 lbs/1000 gal). 

cAPI calculated 0.55 lbs/1000 gal based on the CARB factor of 0.86 lbs/1000 gal (0.86 – 0.31 = 0.55). 

The magnitude of IEE has been the subject of debate for several years, with the American 

Petroleum Institute (API) and the California Air Resources Board (CARB) as primary 

participants in the debate. API and CARB have each overseen testing projects and have come to 

different conclusions regarding IEE. Table 2 (above) summarizes the results and analyses of 

data from recent studies involving Stage II systems manufactured by Gilbarco and WayneDresser. 

When evaluating emissions during refueling of an ORVR-equipped vehicle with a vacuumassisted gasoline dispensing nozzle, the primary difference between the CARB and API factors is 

explained according to how each accounts for emissions at the interface between the nozzle and 

the motor vehicle fill pipe. In arriving at the 0.86 lbs/1000 gal factor, CARB focused solely on 

vapor growth due to excess air in the underground tank. However, API contends there is a 

significant emissions savings with an ORVR-equipped vehicle because essentially no fugitive 

vapor emissions occur at the nozzle-fill pipe interface. API quantified this emissions savings in 

 

13 Stage II Vapor Recovery Systems Issue Paper (and references therein), EPA, August 12, 2004. 
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its phase I report at 0.31 lbs/1000 gal for a net IEE factor of 0.55 lbs/1000 gal. Further in its 

phase II report, API arrived at an even lower vapor growth emissions factor (0.72 lbs/1000 gal) 

and a higher fugitive emissions benefit (0.39 lbs/1000 gal) for a net factor of 0.33 lbs/1000 gal. 

A decision on the most appropriate IEE factor to use in an analysis will have a significant effect 

on determining when ORVR surpasses Stage II as the better stand-alone technology. A lower 

IEE factor, exemplified by the Wayne-Dresser vacuum-assist data (Table 2) and likely related to 

the reduced A/L ratio, will extend the life of effective Stage II programs. California, for 

example, now requires all Stage II systems to be ORVR-compatible. Pursuant to the California 

regulation, balance and vacuum-assist Stage II systems are required to meet a VOC emissions 

standard of 0.38 pounds per 1000 gallons dispensed, based on an uncontrolled emission factor of 

7.6 pounds per 1000 gallons gasoline dispensed. As shown by the data in Appendix C, the result 

of this requirement is to project a continued emissions benefit from maintaining Stage II 

programs in California for more than a decade beyond what other states are likely to achieve 

without ORVR-compatible equipment.. 

For the time being, EPA recommends states use the 0.86 lbs/1000 gal emission factor for nonORVR compatible equipment when performing widespread use analyses.14 At the same time, 

EPA affirms that additional emissions monitoring is needed in order to better characterize IEE. 

Results from subsequent studies ultimately may suggest using a different emission factor, 

perhaps closer to what was demonstrated for Wayne-Dresser systems, particularly if lower limits 

are stipulated for A/L ratios. The table in Appendix E, using the metropolitan Atlanta data as an 

example, illustrates how varying the IEE factor affects the date when an ORVR-only program 

yields a better emissions result, compared to maintaining Stage II in conjunction with ORVR. 

Widespread Use Analysis

A state’s decision to amend its implementation plan to discontinue Stage II and for ORVR to 

become the exclusive means for controlling gasoline refueling emissions will be facilitated by 

findings that when the change occurs, it will be emissions neutral at a minimum, and preferably 

achieve an emissions benefit. Emissions-based analyses for all states, however, may be 

unnecessary if it is possible to identify surrogates that reliably project nearly the same timeframe 

for making the change as what would be projected from comparing emissions between the two 

programs. 

In 2002, API commissioned an independent assessment of the relative importance of the above 

factors and how, in combination, they affect the efficacy of ORVR relative to Stage II. Many of 

API’s members are responsible for implementing Stage II and therefore have an economic and 

regulatory stake in the Stage II program. API contracted with a consultant to develop a 

spreadsheet-based model to project emissions and enable comparisons between varying ORVR 

and Stage II scenarios. API’s consultant modeled emissions scenarios for several states, and API 

shared the model and the results with EPA. 

In 2004, EPA’s Emissions Monitoring and Analysis Division within OAQPS published its Stage 

II Vapor Recovery Systems Issues Paper as a means to promote discussion of EPA’s preliminary 

ideas regarding ORVR widespread use and to solicit comments from stakeholders. The Issues 

 

14 Stage II Vapor Recovery Systems – Options Paper (Draft), EPA-OAQPS, February 7, 2006. 
NESCAUM 

ORVR Widespread Use Analysis 

August 20, 2007 

13

Paper listed four definitions (labeled (a), (b), (c), and (d)) under consideration for defining 

widespread use. In response, API suggested a variant of Definition (c), referred to as (c2).15

 

The emissions-based definitions of widespread use are: 

• Definition (c): Widespread use of ORVR is achieved when VOC emissions (tons per 

summer day) under an ORVR-only scenario equal VOC emissions under a Stage II-only 

scenario. 

• Definition (c2): Widespread use of ORVR is achieved when VOC emissions (tons per 

summer day) under a prospective ORVR-only scenario equal VOC emissions under a real 

world combination scenario in which (1) Stage II controls are in place, (2) both ORVR 

and non-ORVR equipped vehicles are fueling at Stage II equipped stations, and (3) 

fueling of the ORVR equipped vehicles is creating incompatibility excess emissions 

(IEE) between the two systems. 

The surrogate definitions of widespread use are: 

• Definition (a): Widespread use of ORVR is achieved when a specified percentage of the 

in-use light-duty vehicle fleet is equipped with ORVR systems. The 2005 analysis 

highlighted 85 percent, 90 percent, and 95 percent scenarios. For comparison purposes, 

this report also highlights the 80 percent scenario in addition to the other three scenarios. 

• Definition (b): Widespread use of ORVR is achieved when a specified percentage of the 

vehicle miles traveled (VMT) by the in-use light duty fleet is attributable to ORVR 

equipped vehicles. The 2005 analysis and this analysis highlight 90 percent and 

95 percent scenarios. 

• Known as Definition (d), widespread use of ORVR is achieved when a specified 

percentage of the gasoline throughput is attributable to ORVR equipped vehicles. The 

2005 analysis and this analysis highlight 85 percent, 90 percent, and 95 percent scenarios. 

In 2005, EPA and its own consultant expanded upon the API analytical tool, building in further 

assumptions and worked through NESCAUM to gather data and perform similar analyses for 

three of the NESCAUM states: Massachusetts, New Hampshire, and Vermont. Stage II is 

required state-wide in Massachusetts and Vermont and in the more populous Merrimack Valley 

and seacoast areas of southern New Hampshire. The results of these analyses16 are in Appendix 

B and summarized in Table 3. EPA has stated its preferred definition is Definition (c2). 

Therefore, Table 3 shades the Definition (c2) results to identify these as EPA’s preferred 

emissions-neutral scenario for when Stage II may be discontinued. For comparison purposes, 

Table 3 has similar shading in the rows for Definitions (a), (b), and (d) to identify which results 

under these definitions yield dates that most closely match the dates derived from EPA’s 

preferred Definition (c2). For example, under Definition (b), the closest match to Definition (c2) 

occurs when 90 percent of the VMT in each state is by ORVR-equipped vehicles.

 

15 For a fuller comparison of Definition (c2) versus Definition (c), see Appendix D. 

16 Source: Stage II Vapor Recovery Systems - Options Paper (Draft), EPA-OAQPS, February 2006. 
NESCAUM 

ORVR Widespread Use Analysis 

August 20, 2007 

14

Table 3 – Summary of 2005 Analysis for Three NESCAUM States

Definition Description Massachusetts 

Effective Date 

New Hampshire 

Effective Date 

Vermont 

Effective Date 

(c) 

Emissions from 

ORVR-only equal 

emissions from 

Stage II-only 

2010 2008 2008 

(c2) 

Emissions from 

ORVR-only equal 

emissions from 

combination of 

ORVR and Stage II 

plus IEE 

2013 2013 2015 

80% of fleet with 

ORVR 2013 

85% of fleet with 

ORVR 2015 

90% of fleet with 

ORVR 2017 

 (a) 

95% of fleet with 

ORVR 2023 

85% of VMT from 

ORVR-equipped 

vehicles 

2011 2012 2013 

90% of VMT from 

ORVR-equipped 

vehicles 

(b) 2012 2013 2015 

95% of VMT from 

ORVR-equipped 

vehicles 

2015 2016 2019 

85% of gasoline 

dispensed to ORVRequipped vehicles 

2011 2012 2013 

90% of gasoline 

dispensed to ORVRequipped vehicles 

(d) 2013 2014 2016 

95% of gasoline 

dispensed to ORVRequipped vehicles 

2016 2018 2021 

At the same time, EPA recognized that decisions affecting determination of widespread use 

would have national implications. Therefore, it was important to have data from similar analyses 

for states outside of the NESCAUM region to support policy decisions. In 2007, EPA contracted 

with NESCAUM to perform the expanded analyses. With assistance from the National 

Association of Clean Air Agencies (NACAA), NESCAUM solicited participation in the 

expanded study from states outside the NESCAUM region. Four states expressed interest and a 

willingness to provide data (California, Delaware, Georgia, and Pennsylvania) and all were 

selected to participate. The results of the expanded analysis are in Appendix C and summarized 

in Table 4. 

 
NESCAUM 

ORVR Widespread Use Analysis 

August 20, 2007 

15

Table 4 – Summary of 2007 Analysis for Four Additional States

Definition Description California17

Effective Date 

Delaware 

Effective 

Date 

Georgia 

Effective 

Date 

Pennsylvania 

Effective 

Date 

(c) 

Emissions from 

ORVR-only 

equal emissions 

from Stage IIonly 

2012 2011 2010 2009 

(c2) 

Emissions from 

ORVR-only 

equal emissions 

from 

combination of 

ORVR and Stage 

II plus IEE 

N/A 2013 2012 2013 

80% of fleet with 

ORVR 2014 2012 2012 2012 

85% of fleet with 

ORVR 2015 2014 2013 2013 

90% of fleet with 

ORVR 2018 2016 2015 2015 

(a) 

95% of fleet with 

ORVR 2022 2019 2018 2018 

85% of VMT 

from ORVRequipped 

vehicles 

2014 2012 2011 2012 

90% of VMT 

from ORVRequipped 

vehicles 

(b) 2016 2013 2013 2014 

95% of VMT 

from ORVRequipped 

vehicles 

2022 2016 2016 2017 

85% of gasoline 

dispensed to 

ORVR-equipped 

vehicles 

2014 2012 2012 2013 

90% of gasoline 

dispensed to 

ORVR-equipped 

vehicles 

(d) 2017 2014 2013 2015 

95% of gasoline 

dispensed to 

ORVR-equipped 

vehicles 

2021 2018 2017 2018 

Of the four additional states, Delaware was the only one where the analysis addressed a program 

covering the entire state. The analysis for California covered only the South Coast Air Basin 

 

17 Data are for California’s South Coast Air Basin only. 
NESCAUM 

ORVR Widespread Use Analysis 

August 20, 2007 

16

(metropolitan Los Angeles). In Georgia and Pennsylvania, Stage II programs are only in effect in 

the major metropolitan areas. These analyses therefore were confined respectively to 

metropolitan Atlanta and metropolitan Philadelphia.18 NESCAUM subcontracted with EPA’s 

consultant from the 2005 study (RTI International) to perform the modeling. Effective dates for 

California are presented in the table but for reasons discussed below, no California dates are 

highlighted. 

Options for Establishing ORVR Widespread Use Dates

As indicated previously, CAA § 202(a)(6) authorizes EPA to waive the requirements for Stage II 

once it is determined that ORVR systems are in widespread use throughout the motor vehicle 

fleet. Consistent with EPA’s preferred Definition (c2), it is expected that when ORVR by itself 

achieves the same or a better emissions benefit compared to the benefits achieved in the present 

situation (i.e., Stage II systems operating in conjunction with ORVR on most light-duty 

vehicles), Stage II programs can be discontinued without causing refueling emissions to increase. 

NESCAUM has identified several possible options upon which to base such decisions. The 

options are presented in this section. 

Require every state to conduct an emissions-based (Definition (c2)) analysis. This approach 

would best ensure that emissions will not increase when Stage II programs are discontinued. 

However, it is the most complex of the various approaches. 

Require ORVR-compatible Stage II systems. California adopted a regulation, effective March 1, 

2006, requiring all Stage II systems to be ORVR-compatible. With the use of a processor, 

vacuum-assist systems are able to contain the vapor growth problem discussed above and 

thereby meet the California standard. As indicated by the graph in Appendix C, the South Coast 

Air Basin will continue to realize an emissions benefit from the ORVR-compatible Stage II 

requirement until essentially 100 percent of the light-duty vehicles in the fleet are equipped with 

ORVR. Even as late as 2030, the emissions benefit over ORVR as a stand-alone program will be 

almost 0.8 tons per summer day. Other states could consider requiring Stage II equipment to 

meet the California certification for ORVR compatibility, and thereby extend the benefits 

achieved by Stage II and ORVR programs in tandem for many years. 

Establish a single national date for authorizing discontinuation of Stage II programs. According 

to the analyses conducted for six states (excluding California), Stage II programs could be 

discontinued without an emissions increase in five of the states on or before 2013. Vermont was 

the only state that projected a later date (2015). According to the analysis, if Vermont were to 

discontinue Stage II in 2013, there would be an emissions increase of 0.08 tons per summer day. 

Based on these results, EPA could establish 2013 as the widespread use date for all states. States 

that have concerns about potential emissions increases associated with removing Stage II in 2013 

could delay the change to a later date. Alternatively, EPA could establish a later date (e.g., 2015) 

and allow individual states the option of preparing technical analyses to justifying an earlier date. 

 

18 Stage II is also in effect in metropolitan Pittsburgh, Pennsylvania, but this area was not included in the analyses. 
NESCAUM 

ORVR Widespread Use Analysis 

August 20, 2007 

17

Use ORVR fleet penetration as a surrogate. According to the analyses for four of the states,19 

the Definition (a) date either matches the Definition (c2) date or exceeds it by no more than one 

year when 85 percent of the state fleet of light-duty vehicles is ORVR-equipped. 

Use ORVR VMT penetration as a surrogate. According to the analyses of six states (excluding 

California) in five of the six scenarios, the Definition (b) date either matches the Definition (c2) 

date or exceeds it by no more than one year when 90 percent of the vehicle miles traveled (VMT) 

are attributed to ORVR-equipped light-duty vehicles. In the case of Massachusetts, the 

Definition (b) date (2012) precedes the Definition (c2) date (2013) by one year. If Massachusetts 

were to discontinue Stage II in 2012, the analysis indicates that there would be an emissions 

increase of 0.23 tons per day. In reality, the 2012 date for Massachusetts reflects an 88 percent 

VMT threshold, so when the 90 percent threshold is achieved sometime between 2012 the 2013 

summer seasons, there is actually a small emissions benefit from discontinuing Stage II. 

Use ORVR gasoline throughput penetration as a surrogate. According to the analysis of six 

states (excluding California), the Definition (d) date will match the Definition (c2) date when 

somewhere between 85 percent and 90 percent of the gasoline is dispensed to ORVR-equipped 

light-duty vehicles. At 85 percent throughput, the result is the same as projected by Definition 

(c2) for Georgia and Pennsylvania. At 85 percent throughput for the other four states, the 

Definition (d) date occurs one to two years earlier than the date predicted by Definition (c2), 

meaning emissions will increase somewhat in those states if Stage II is discontinued according to 

Definition (d). At the 90 percent throughput threshold, only Massachusetts achieves the same 

result (2013) under both definitions. The other five states are delayed from one to two years 

under Definition (d) beyond the Definition (c2) date. 

Stakeholders Meetings

In May 2007, NESCAUM hosted a stakeholders meeting in Manchester, NH, to discuss 

transitioning from Stage II programs to exclusively ORVR programs. At the meeting, there was 

general support among the participating states for ensuring that the result of Stage II removal 

was emissions neutral and would properly address soil and groundwater contamination and the 

potential for on-going fugitive emissions from discontinued Stage II systems. At least one state 

favored retaining discretion to remove Stage II in advance of a date strictly imposed under the 

Definition (c2) approach as long as excess emissions were offset by other measures. States also 

favored having the option to use alternative metrics. 

State Workgroup Recommendations

There was general agreement among the states that EPA should allow use of alternative metrics 

for states to establish their widespread use dates. In particular, the states favored the following: 

• 85 percent of ORVR fleet penetration (Definition (a)) 

• 90 percent of VMT attributed to ORVR-equipped vehicles (Definition (b)) 

In addition, there was agreement that states should not be precluded from establishing dates other 

than those predicted by the metrics, provided states are able to demonstrate through technical 

analyses that a chosen date does not cause emissions to increase. Further, states may choose to 

 

19 California is excluded because of its ORVR-compatibility requirements for Stage II. No data on ORVR 

penetration were generated for Massachusetts or New Hampshire in the 2005 study. 
NESCAUM 

ORVR Widespread Use Analysis 

August 20, 2007 

18

perpetuate their Stage II programs while requiring exclusive use of ORVR compatible equipment 

in lieu of earlier termination of the program. 

 

Conclusions and Recommendations

As increasing numbers of ORVR-equipped motor vehicles replace those without ORVR, most 

SIP-approved Stage II programs are approaching a point where the incremental emissions benefit 

disappears. When states perform analyses to project the year in which this point is attained, they 

will be poised to prepare amendments to their ozone attainment or maintenance plans to 

discontinue Stage II programs and at the same time meet the no-backsliding requirements 

pursuant to the Clean Air Act. 

The level of the Incompatibility Excess Emissions (IEE) factor to use in these analyses will have 

a significant effect on determining when ORVR surpasses Stage II as the better stand-alone 

technology. A lower IEE factor will have the effect of extending the life of effective Stage II 

programs. A higher factor will have the opposite effect. EPA previously affirmed that 

additional emissions monitoring was needed to better characterize IEE and that the results from 

subsequent studies may suggest using an emissions factor that is different from the one used in 

this analysis. It will be helpful to states that are soon to embark on preparing SIP amendments to 

receive updated guidance in the short term from EPA regarding the appropriate IEE factor to use 

and related guidance on appropriate A/L ratios for vacuum-assist Stage II systems. 

States choosing to follow the California example by requiring all Stage II systems to be ORVRcompatible may be able to extend the effective life of their Stage II programs. Alternately, EPA 

can facilitate the efforts of states choosing to establish a closer date for discontinuing their Stage

II programs, based on the technology in place, by allowing use of alternative metrics, such as 

those based on ORVR fleet penetration or vehicle miles traveled by ORVR-equipped vehicles. 

At the same time, EPA may wish to consider allowing states to establish dates other than those 

predicted by the metrics, provided states are able to demonstrate through technical analyses and 

possibly substitute control measures that a chosen date for discontinuing Stage II will not result 

in an emissions increase. 
A-1

APPENDIX A 

ONBOARD REFUELING VAPOR RECOVERY REQUIREMENTS 

EXCERPTS FROM THE CODE OF FEDERAL REGULATIONS 

40 CFR 86.1810-01(k) 

 (k) Refueling emissions general provisions —(1) Implementation schedules. (i) Tables S01–3, 

S01–4, and S01–5 in this paragraph (k)(1)(i) give the minimum percentage of a manufacturer's 

sales of the applicable model year's gasoline- and methanol-fueled Otto-cycle and petroleumfueled and methanol-fueled diesel-cycle light-duty vehicles, light-duty trucks and complete 

heavy-duty vehicles which shall be tested under the applicable procedures in subpart B of this 

part, and shall not exceed the standards described in §§86.1811–01(e), 86.1811–04(e)(3), 

86.1812–01(e), 86.1813–01(e), and 86.1816–04(e). Vehicles waived from the emission standards 

under the provisions of paragraphs (m) and (n) of this section shall not be counted in the 

calculation of the percentage of compliance. Either manufacturer sales or actual production 

intended for sale in the United States may be used to determine combined volume, at the 

manufacturer’s option. Tables S01–3, S01–4, and S01–5 follow: 

Table S01–3—Light-Duty Vehicles 

Model Year Percentage 

1998a 40

1999a 80

2000a 100

a Note: This subpart prescribes standards for 2001 and later MY vehicles. However, the 

implementation phase-in periods prior to this date are included for ease of reference. 

Table S01–4—Light Light-Duty Trucks 

Model Year Percentage 

2001 40

2002 80

2003 100

Table S01–5—Heavy Light-Duty Trucks 

Model Year Percentage 

2004 40

2005 80

2006 100
A-2

40 CFR 86.1811-04(e) 

(3) Refueling emission standards. Refueling emissions must not exceed the following standards: 

(i) For gasoline-fueled, diesel-fueled and methanol-fueled LDVs, LDTs and MDPVs: 0.20 grams 

hydrocarbon per gallon (0.053 grams per liter) of fuel dispensed. 

(ii) For liquefied petroleum gas-fueled LDV, LDTs and MDPVs: 0.15 grams hydrocarbon per 

gallon (0.04 grams per liter) of fuel dispensed. 

(iii) Refueling standards for HLDTs are subject to the phase-in requirements found in §86.1810–

01(k). MDPVs must also comply with the phase-in requirement in §86.1810–01(k) and must be 

grouped with HLDTs to determine phase-in compliance. 

40 CFR 86.1816-05(e) 

(e) Refueling emissions —(1) Standards. Refueling emissions from Otto-cycle complete heavyduty vehicles equal to or less than 10,000 pounds Gross Vehicle Weight Rating shall be phased 

in, in accordance with the schedule in Table S01–5 in §86.1810–01 not to exceed the following 

emission standards: 

(i) For gasoline-fueled and methanol-fueled vehicles: 0.20 grams hydrocarbon per gallon (0.053 

gram per liter) of fuel dispensed. 

(ii) For liquefied petroleum gas-fueled vehicles: 0.15 grams hydrocarbon per gallon (0.04 gram 

per liter) of fuel dispensed. 

(2) Phase-in. Complete heavy-duty vehicles subject to refueling standards must comply with the 

phase-in requirements found in Table S01–5 in §86.1810–01, and must be grouped with HLDTs 

and MDPVs to determine phase-in compliance. 

40 CFR 86.1803-01 Definitions. 

Complete heavy-duty vehicle means any Otto-cycle heavy-duty vehicle of 14,000 pounds Gross 

Vehicle Weight Rating or less that has the primary load carrying device or container attached at 

the time the vehicle leaves the control of the manufacturer of the engine. 

Heavy light-duty truck means any light-duty truck rated greater than 6000 lbs GVWR. The LDT3 

and LDT4 classifications comprise the heavy light-duty truck category. 

Light light-duty truck means any light-duty truck rated up through 6000 lbs GVWR. The LDT1 

and LDT2 classifications compose the light light-duty truck category. 
A-3

Light-duty truck means any motor vehicle rated at 8,500 pounds GVWR or less which has a curb 

weight of 6,000 pounds or less and which has a basic vehicle frontal area of 45 square feet or 

less, which is: 

(1) Designed primarily for purposes of transportation of property or is a derivation of such a 

vehicle; or 

(2) Designed primarily for transportation of persons and has a capacity of more than 12 persons; 

or 

(3) Available with special features enabling off-street or off-highway operation and use. 

Light-duty truck 1 (LDT1) means any light light-duty truck up through 3750 lbs loaded vehicle 

weight. 

Light-duty truck 2 (LDT2) means any light light-duty truck greater than 3750 lbs loaded vehicle 

weight. 

Light-duty truck 3 (LDT3) means any heavy light-duty truck up through 5750 lbs adjusted loaded 

vehicle weight. 

Light-duty truck 4 (LDT4) means any heavy light-duty truck greater than 5750 lbs adjusted 

loaded vehicle weight. 

Light-duty vehicle means a passenger car or passenger car derivative capable of seating 12 

passengers or less. 

Medium-duty passenger vehicle (MDPV) means any heavy-duty vehicle (as defined in this 

subpart) with a gross vehicle weight rating (GVWR) of less than 10,000 pounds that is designed 

primarily for the transportation of persons. The MDPV definition does not include any vehicle 

which: 

(1) Is an “incomplete truck” as defined in this subpart; or 

(2) Has a seating capacity of more than 12 persons; or 

(3) Is designed for more than 9 persons in seating rearward of the driver's seat; or 

(4) Is equipped with an open cargo area (for example, a pick-up truck box or bed) of 72.0 inches 

in interior length or more. A covered box not readily accessible from the passenger compartment 

will be considered an open cargo area for purposes of this definition. 
APPENDIX B 

ORVR WIDESPREAD USE ANALYSIS 

FOR 

MASSACHUSETTS, NEW HAMPSHIRE, & VERMONT 

(2005 ANALYSIS) 
MASSACHUSETTS

(IEE 0.86)

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 Stain place, without OREmissions with only requirements, withoEmissions with Stagincluding "excess emlb/1000 gal for VacuEmissions with Stagwithout "excess emiORVR Penetration, % VMT ORVR Penetration, definition,% fuel disp

"Widespread use" date under option (c)

"Widespread use" date under option 

(c2)
TOTAL REFUELING EMISSIONS –MASSACHUSETTS (Calculations assume all VA have IEE of 0.86, uncorrected) 

Grams Emitted Per Gallon Gasoline Tons Per Summer Day 

Calendar Year 

Stage II Controls Only 

ORVR Only 

Stage II with ORVR, No IEE 

Stage II with ORVR, 

IEE

% Decrease from Uncontrolled Emissions 

Stage II Controls Only 

ORVR Only 

Stage II wORVR, NIEE 

2001 0.682 2.307 0.617 0.649 75% 5.92 20.02 5.35 2002 0.682 2.147 0.585 0.633 76% 6.01 18.93 5.16 2003 0.689 2.005 0.556 0.622 77% 6.18 17.97 4.98 2004 0.690 1.813 0.518 0.602 78% 6.28 16.51 4.72 2005 0.690 1.599 0.476 0.581 78% 6.38 14.78 4.40 2006 0.690 1.373 0.432 0.559 79% 6.48 12.90 4.06 2007 0.690 1.166 0.391 0.538 80% 6.57 11.12 3.73 2008 0.690 0.982 0.355 0.519 81% 6.67 9.50 3.44 2009 0.690 0.823 0.324 0.504 81% 6.77 8.08 3.18 2010 0.690 0.687 0.297 0.490 82% 6.87 6.84 2.96 2011 0.690 0.578 0.276 0.479 82% 6.97 5.84 2.79 2012 0.690 0.494 0.259 0.471 83% 7.07 5.06 2.66 2013 0.690 0.428 0.246 0.464 83% 7.17 4.45 2.56 2014 0.690 0.378 0.237 0.459 83% 7.27 3.98 2.49 2015 0.690 0.342 0.230 0.456 83% 7.36 3.65 2.45 2016 0.690 0.317 0.225 0.453 83% 7.46 3.43 2.43 2017 0.690 0.299 0.221 0.451 83% 7.56 3.27 2.42 2018 0.690 0.286 0.219 0.450 83% 7.66 3.17 2.43 2019 0.690 0.275 0.217 0.449 83% 7.76 3.09 2.44 2020 0.690 0.267 0.215 0.448 83% 7.86 3.04 2.45 2021 0.690 0.260 0.214 0.448 83% 7.95 3.00 2.46 2022 0.690 0.253 0.212 0.447 83% 8.05 2.96 2.48 2023 0.690 0.249 0.211 0.446 83% 8.15 2.94 2.50 2024 0.690 0.246 0.211 0.446 83% 8.24 2.94 2.52 2025 0.690 0.242 0.210 0.446 83% 8.34 2.92 2.54 2026 0.690 0.241 0.210 0.446 83% 8.43 2.95 2.57 2027 0.690 0.241 0.210 0.446 83% 8.53 2.98 2.59 2028 0.690 0.240 0.210 0.446 83% 8.62 3.00 2.62 2029 0.690 0.239 0.209 0.445 83% 8.71 3.01 2.64 2030 0.690 0.238 0.209 0.445 83% 8.81 3.04 2.67 
NEW HAMPSHIRE

(IEE 0.86)

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 Sin place, without OREmissions with only requirements, withoEmissions with Staincluding "excess elb/1000 gal for VacEmissions with Stawithout "excess emORVR Penetration, % VMTORVR Penetration, % fuel dispensed

"Widespread use" date under option (c)

"Widespread use" date under option (c2)
TOTAL REFUELING EMISSIONS - NEW HAMPSHIRE (Calculations assume all VA have IEE of 0.86, uncorrected) 

Grams Emitted Per Gallon Gasoline Tons Per Summ

Calendar 

Year 

Stage II 

Controls 

Only 

ORVR 

Only 

Stage II with 

ORVR, No 

IEE 

Stage II with 

ORVR, IEE 

% Decrease from 

Uncontrolled 

Emissions 

Stage II 

Controls 

Only 

ORVR 

Only 

Stage II wit

ORVR, No IE

2001 1.149 2.604 1.020 1.057 65% 2.41 5.46 2.14 2002 1.149 2.416 0.956 1.011 66% 2.46 5.17 2.05 2003 1.164 2.236 0.895 0.971 68% 2.54 4.88 1.95 2004 1.164 1.998 0.814 0.913 70% 2.59 4.45 1.81 2005 1.164 1.752 0.731 0.854 72% 2.64 3.98 1.66 2006 1.164 1.505 0.647 0.794 74% 2.70 3.49 1.50 2007 1.164 1.299 0.578 0.744 76% 2.75 3.07 1.36 2008 1.164 1.099 0.510 0.696 77% 2.81 2.65 1.23 2009 1.165 0.951 0.460 0.660 78% 2.86 2.34 1.13 2010 1.165 0.817 0.415 0.627 79% 2.92 2.05 1.04 2011 1.164 0.695 0.373 0.598 80% 2.98 1.78 0.95 2012 1.165 0.618 0.347 0.579 81% 3.04 1.61 0.91 2013 1.164 0.538 0.320 0.560 82% 3.10 1.43 0.85 2014 1.165 0.481 0.301 0.546 82% 3.16 1.30 0.82 2015 1.165 0.434 0.285 0.535 82% 3.22 1.20 0.79 2016 1.165 0.395 0.272 0.525 83% 3.29 1.12 0.77 2017 1.165 0.368 0.263 0.519 83% 3.36 1.06 0.76 2018 1.165 0.338 0.253 0.512 83% 3.42 0.99 0.74 2019 1.165 0.319 0.246 0.507 83% 3.49 0.96 0.74 2020 1.165 0.304 0.241 0.503 83% 3.56 0.93 0.74 2021 1.165 0.293 0.238 0.501 84% 3.63 0.91 0.74 2022 1.165 0.282 0.234 0.498 84% 3.70 0.90 0.74 2023 1.165 0.273 0.231 0.496 84% 3.78 0.89 0.75 2024 1.165 0.269 0.229 0.495 84% 3.85 0.89 0.76 2025 1.165 0.265 0.228 0.494 84% 3.93 0.89 0.77 2026 1.165 0.261 0.227 0.493 84% 4.01 0.90 0.78 2027 1.165 0.258 0.226 0.492 84% 4.09 0.91 0.79 2028 1.165 0.255 0.225 0.491 84% 4.17 0.91 0.80 2029 1.165 0.250 0.223 0.490 84% 4.26 0.91 0.82 2030 1.165 0.249 0.223 0.490 84% 4.34 0.93 0.83 
VERMONT

(IEE 0.86)

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 Stawere in place, withoEmissions with only requirements, withoEmissions with Stagincluding "incompatiemissions" of 0.86 lbVacuum Assist Emissions with Stagwithout "excess emiORVR Penetration, definition, % of vehicORVR Penetration, definition, % VMTORVR Penetration, definition, % fuel dis

"Widespread use" date under option (c)

"Widespread use" date under option (c2)
TOTAL REFUELING EMISSIONS – VERMONT (Calculations assume all VA have IEE of 0.86, uncorrected) 

Grams Emitted Per Gallon Gasoline Tons Per Summe

Calendar 

Year 

Stage II 

Controls 

Only 

ORVR 

Only 

Stage II with 

ORVR, No 

IEE 

Stage II with 

ORVR, IEE 

% Decrease 

from 

Uncontrolled 

Emissions

Stage II 

Controls Only 

ORVR 

Only 

Stage II with 

ORVR, No IEE 

2001 1.519 3.094 1.349 1.386 61% 1.57 3.19 1.39 2002 1.519 2.899 1.272 1.327 62% 1.59 3.03 1.33 2003 1.519 2.684 1.188 1.261 64% 1.61 2.84 1.26 2004 1.519 2.453 1.097 1.190 66% 1.56 2.52 1.13 2005 1.520 2.195 0.996 1.111 69% 1.65 2.39 1.08 2006 1.520 1.926 0.890 1.029 71% 1.67 2.12 0.98 2007 1.520 1.676 0.792 0.952 73% 1.69 1.87 0.88 2008 1.520 1.454 0.704 0.884 75% 1.71 1.64 0.79 2009 1.520 1.258 0.627 0.824 77% 1.71 1.42 0.71 2010 1.520 1.086 0.560 0.772 78% 1.76 1.25 0.65 2011 1.520 0.942 0.503 0.728 79% 1.78 1.10 0.59 2012 1.520 0.823 0.456 0.691 80% 1.78 0.97 0.54 2013 1.520 0.724 0.417 0.661 81% 1.82 0.87 0.50 2014 1.520 0.644 0.386 0.636 82% 1.84 0.78 0.47 2015 1.520 0.579 0.360 0.616 83% 1.86 0.71 0.44 2016 1.520 0.527 0.340 0.601 83% 1.88 0.65 0.42 2017 1.520 0.485 0.324 0.588 83% 1.90 0.61 0.40 2018 1.520 0.452 0.311 0.578 84% 1.92 0.57 0.39 2019 1.520 0.426 0.300 0.570 84% 1.94 0.54 0.38 2020 1.520 0.405 0.292 0.563 84% 1.96 0.52 0.38 2021 1.520 0.386 0.285 0.557 84% 1.98 0.50 0.37 2022 1.520 0.369 0.278 0.552 84% 2.00 0.49 0.37 2023 1.520 0.354 0.272 0.548 85% 2.02 0.47 0.36 2024 1.520 0.343 0.268 0.544 85% 2.05 0.46 0.36 2025 1.520 0.330 0.263 0.540 85% 2.07 0.45 0.36 2026 1.520 0.319 0.258 0.537 85% 2.09 0.44 0.35 2027 1.520 0.311 0.255 0.534 85% 2.11 0.43 0.35 2028 1.520 0.301 0.251 0.531 85% 2.13 0.42 0.35 2029 1.520 0.290 0.247 0.528 85% 2.15 0.41 0.35 2030 1.520 0.286 0.245 0.527 85% 2.17 0.41 0.35 
APPENDIX C 

ORVR WIDESPREAD USE ANALYSIS 

FOR 

CALIFORNIA, DELAWARE, GEORGIA, & PENNSYLVANIA 

(2007 ANALYSIS) 
Data Summary for 4 States

 Denotes that State-provided data were used for this parameter in the analysis, but the data set is too large to 

adequately describe here. 

a In CA SCAQMD, beginning in 2009, the CE: 95% (given); RE: 87.5%; RP: 94.7%; and In-use: 78.7%.

Provided Data 

Or 

MOBILE6 Defaults Used 

Requested Data CA DE GA PA 

Stage II VRS In-Use Effectiveness CE: 95% (given) 

RE: 87.5% 

RP: 81.6% 

In-use: 67.8% a

CE: 95% (given) 

RE: 90.5% 

RP: 98.7% 

In-use: 85% 

CE: 95% (given) 

RE: 95% 

RP: 90% 

In-use: 81% 

CE: 95% (given) 

RE: 80% 

RP: 96% 

In-use: 73% 

Ambient Temperature Data Used 24 hrly avg T 

data 

Min: 69.25oF 

Max: 87.35oF 

Used 24 hrly avg T 

data; 2 sets 

Min: 70.2oF 

Max: 87.5oF 

In-use RVP of the gasoline used during the summer 

ozone season, and indicate if the gasoline is RFG 

6.8 psia; 

Yes 

6.81 psia 

6.57 psia; 

Yes 

7.0 psia; 

No 

6.81 psia; 

Yes 

Total gasoline usage, gallons/yr for the most recent 

available CYs and for those years that the states 

have projected data 

   

Percentage of GDFs equipped with balance Stage II 

VRS 

90% 18% 6.7% 20% 

Percentage of GDFs equipped with vacuum assist 

Stage II VRS 

10% 82% 93.3% 80% 

With Stage I but no Stage II VRS, 

With Stage I but no P/V valve, 

With Stage I and with P/V valve 

0% 

0% 

100% 

0% 

0% 

100% 

16.5% 

0% 

83.5% 

0% 

1% 

99% 

Balance Stage II VRS but no Stage I, 

Balance Stage II VRS and Stage I but no P/V valve, 

Balance Stage II VRS and Stage I with P/V valves 

0% 

0% 

100% 

0% 

0% 

100% 

0% 

0% 

100% 

0% 

2% 

98% 

VA Stage II VRS but no Stage I, 

VA Stage II VRS and Stage I but no P/V valve, 

VA Stage II VRS and Stage I with P/V valves 

0% 

0% 

100% 

0% 

0% 

100% 

0% 

0% 

100% 

0% 

1% 

99% 

Vehicle registration data (defn a) 

Gasoline only 



Gasoline only 



Fuel-independent 



Fuel-independent 

Vehicle distribution data by vehicle type and age 

Gasoline only 



Gasoline only 



Fuel-independent; 

Default for HDV8a 

class 



Fuel-independent 

Vehicle mileage accumulation data, AMAR 

Gasoline only 

Default Default Default 

Vehicle miles traveled (VMT) for the most recent 

calendar year and any years where projected data 

are available 



Gasoline only 



Fuel-independent 



Fuel-independent 



Fuel-independent 

VMT fractional mix (represents the fraction of total 

highway VMT accumulated by each vehicle type) 

Estimate from 

VMT info by 

vehicle type above 



Fuel-independent 



Fuel-independent 

Estimate from 

VMT info by 

vehicle type above 

Diesel sales fraction data Not needed, as 

VMT is Gasoline 

only 

Default Default Default 

Vehicle fuel economy data  Default Default Default 

Anti-Tampering Program data    
LOS ANGELES, CA Area - Emissions and ORVR Percenta

for Merged Data 2001 through 2030

05

101520253035404550

2001 2006 2011 2016 2021 2026

Emissions (tons/summer day)

0%10%20%30%40%50%60%70%80%90%100%

% PenetrationEmissions if only Stag

place, without ORVR Emissions with only Owithout Stage II controEmissions with Stage "excess emissionsORVR Penetration, opvehiclesORVR Penetration, opVMTORVR Penetration, opfuel dispensed

"Widespread use" date under option (c)
TOTAL REFUELING EMISSIONS - California (Los Angeles Area) (Calculations assume all VA have IEE of 0.86, uncorrected) 

Grams Emitted Per Gallon Gasoline Tons Per Summ

Calendar 

Year 

Stage II 

Controls 

Only 

ORVR 

Only 

Stage II with 

ORVR, No 

IEE 

Stage II with 

ORVR, IEE 

% Decrease 

from 

Uncontrolled 

Emissions

Stage II 

Controls 

Only ORVR Only 

Stage II wit

ORVR, No 

IEE 

2001 1.114 2.330 0.947 0.948 66% 19.29 40.35 16.40 2002 1.114 2.166 0.890 0.892 68% 19.68 38.28 15.73 2003 1.129 2.055 0.850 0.853 70% 20.72 37.73 15.61 2004 1.128 1.894 0.794 0.798 72% 21.81 36.62 15.35 2005 1.128 1.716 0.732 0.737 74% 22.22 33.80 14.42 2006 1.128 1.511 0.661 0.666 77% 21.57 28.89 12.63 2007 1.128 1.307 0.589 0.594 79% 20.89 24.19 10.91 2008 1.128 1.124 0.526 0.532 81% 21.07 21.00 9.82 2009 0.651 0.885 0.303 0.311 89% 12.26 16.67 5.71 2010 0.651 0.781 0.283 0.291 90% 12.36 14.82 5.37 2011 0.651 0.699 0.267 0.276 90% 12.47 13.38 5.10 2012 0.651 0.630 0.253 0.263 91% 12.58 12.17 4.89 2013 0.651 0.567 0.241 0.251 91% 12.72 11.08 4.70 2014 0.651 0.511 0.229 0.241 92% 12.82 10.05 4.52 2015 0.651 0.461 0.220 0.232 92% 12.93 9.16 4.36 2016 0.651 0.420 0.212 0.224 92% 12.99 8.37 4.22 2017 0.651 0.385 0.205 0.218 92% 13.07 7.74 4.11 2018 0.651 0.359 0.200 0.213 93% 13.17 7.26 4.04 2019 0.651 0.338 0.195 0.209 93% 13.28 6.89 3.98 2020 0.651 0.320 0.192 0.206 93% 13.40 6.58 3.95 2021 0.651 0.305 0.189 0.204 93% 13.46 6.30 3.90 2022 0.651 0.285 0.185 0.200 93% 13.54 5.91 3.84 2023 0.651 0.268 0.182 0.197 93% 13.62 5.60 3.80 2024 0.651 0.257 0.180 0.196 93% 13.75 5.43 3.79 2025 0.651 0.240 0.176 0.193 93% 13.88 5.12 3.75 2026 0.651 0.223 0.173 0.190 93% 14.00 4.79 3.71 2027 0.651 0.214 0.171 0.188 93% 14.13 4.63 3.71 2028 0.651 0.210 0.170 0.188 93% 14.26 4.60 3.73 2029 0.651 0.205 0.169 0.188 93% 14.39 4.53 3.74 2030 0.651 0.203 0.169 0.188 93% 14.53 4.54 3.77 
DELAWARE - Emissions and ORVR Percentages

(IEE 0.86)

01234

2001 2006 2011 2016 2021 2026

Emissions (tons/summer day)

0%10%20%30%40%50%60%70%80%90%100%

% PenetrationEmissions if only Stag

place, without ORVR Emissions with only Owithout Stage II controEmissions with Stage "incompatibility excess lb/1000 gal for Vacuum Emissions with Stage "excess emissionsORVR Penetration, opvehiclesORVR Penetration, opVMTORVR Penetration, opfuel dispensed

"Widespread use" date under option (c)

"Widespread use" date under option (c2)
TOTAL REFUELING EMISSIONS – Delaware (Calculations assume all VA have IEE of 0.86, uncorrected) 

Grams Emitted Per Gallon Gasoline Tons Per Summer 

Calendar 

Year 

Stage II 

Controls 

Only 

ORVR 

Only 

Stage II 

with ORVR, 

No IEE 

Stage II with 

ORVR, IEE 

% Decrease 

from 

Uncontrolled 

Emissions

Stage II 

Controls 

Only 

ORVR 

Only 

Stage II with 

ORVR, No 

IEE 

2001 0.718 2.688 0.656 0.698 77% 0.83 3.09 0.75 2002 0.718 2.500 0.622 0.687 77% 0.85 2.97 0.74 2003 0.725 2.322 0.589 0.681 78% 0.88 2.81 0.71 2004 0.725 2.092 0.548 0.667 78% 0.90 2.61 0.68 2005 0.725 1.840 0.503 0.653 79% 0.93 2.35 0.64 2006 0.725 1.580 0.456 0.637 79% 0.92 2.00 0.58 2007 0.725 1.348 0.414 0.624 80% 0.93 1.73 0.53 2008 0.725 1.149 0.379 0.612 80% 0.95 1.50 0.49 2009 0.725 0.978 0.348 0.602 81% 0.95 1.29 0.46 2010 0.725 0.832 0.322 0.593 81% 0.97 1.12 0.43 2011 0.725 0.715 0.301 0.586 81% 0.99 0.97 0.41 2012 0.725 0.622 0.284 0.581 81% 1.00 0.85 0.39 2013 0.725 0.545 0.270 0.576 81% 1.01 0.76 0.38 2014 0.725 0.482 0.259 0.573 81% 1.03 0.68 0.37 2015 0.725 0.431 0.250 0.570 82% 1.04 0.62 0.36 2016 0.725 0.393 0.243 0.568 82% 1.05 0.57 0.35 2017 0.725 0.364 0.238 0.566 82% 1.07 0.54 0.35 2018 0.725 0.344 0.234 0.565 82% 1.08 0.51 0.35 2019 0.725 0.328 0.231 0.564 82% 1.10 0.49 0.35 2020 0.725 0.315 0.229 0.563 82% 1.11 0.48 0.35 2021 0.725 0.305 0.227 0.562 82% 1.12 0.47 0.35 2022 0.725 0.293 0.225 0.562 82% 1.14 0.46 0.35 2023 0.725 0.283 0.223 0.561 82% 1.15 0.45 0.35 2024 0.725 0.277 0.222 0.561 82% 1.16 0.44 0.36 2025 0.725 0.274 0.222 0.561 82% 1.18 0.44 0.36 2026 0.725 0.272 0.221 0.560 82% 1.19 0.45 0.36 2027 0.725 0.271 0.221 0.560 82% 1.20 0.45 0.37 2028 0.725 0.270 0.221 0.560 82% 1.22 0.45 0.37 2029 0.725 0.268 0.220 0.560 82% 1.23 0.45 0.37 2030 0.725 0.267 0.220 0.560 82% 1.24 0.46 0.38 
GEORGIA - Emissions and ORVR Percentages

(IEE 0.86)

05

10152025

2001 2006 2011 2016 2021 2026

Emissions (tons/summer day)

0%10%20%30%40%50%60%70%80%90%100%

% PenetrationEmissions if only Stag

place, without ORVR Emissions with only Owithout Stage II controEmissions with Stage "incompatibility excess lb/1000 gal for Vacuum Emissions with Stage "excess emissionsORVR Penetration, opvehiclesORVR Penetration, opVMTORVR Penetration, opfuel dispensed

"Widespread use" date under option (c)

"Widespread use" date under option (c2)
TOTAL REFUELING EMISSIONS – Georgia (Calculations assume all VA have IEE of 0.86, uncorrected) 

Grams Emitted Per Gallon Gasoline Tons Per Summe

Calendar 

Year 

Stage II 

Controls 

Only 

ORVR 

Only 

Stage II 

with ORVR, 

No IEE 

Stage II with 

ORVR, IEE 

% Decrease 

from 

Uncontrolled 

Emissions

Stage II 

Controls Only 

ORVR 

Only 

Stage II with 

ORVR, No IEE 

2001 0.854 2.856 0.785 0.825 74% 6.35 21.23 5.83 2002 0.854 2.681 0.747 0.810 75% 6.40 20.11 5.60 2003 0.854 2.474 0.702 0.792 75% 6.59 19.11 5.42 2004 0.854 2.239 0.651 0.771 76% 6.70 17.57 5.11 2005 0.854 1.958 0.590 0.746 77% 6.72 15.40 4.64 2006 0.854 1.634 0.520 0.718 77% 6.82 13.05 4.15 2007 0.854 1.348 0.458 0.693 78% 6.97 11.01 3.74 2008 0.854 1.118 0.408 0.673 79% 7.13 9.33 3.41 2009 0.854 0.937 0.369 0.657 79% 7.28 7.99 3.15 2010 0.854 0.797 0.339 0.645 80% 7.44 6.94 2.95 2011 0.854 0.680 0.313 0.636 80% 7.57 6.03 2.78 2012 0.854 0.584 0.293 0.627 80% 7.70 5.27 2.64 2013 0.854 0.508 0.276 0.621 80% 7.83 4.66 2.53 2014 0.854 0.452 0.264 0.617 81% 7.96 4.22 2.46 2015 0.854 0.413 0.256 0.614 81% 8.09 3.92 2.42 2016 0.854 0.386 0.250 0.611 81% 8.19 3.71 2.40 2017 0.854 0.365 0.245 0.610 81% 8.30 3.55 2.38 2018 0.854 0.349 0.242 0.609 81% 8.40 3.43 2.38 2019 0.854 0.334 0.239 0.608 81% 8.51 3.33 2.38 2020 0.854 0.324 0.236 0.607 81% 8.61 3.26 2.38 2021 0.854 0.315 0.234 0.607 81% 8.72 3.22 2.39 2022 0.854 0.304 0.232 0.606 81% 8.83 3.14 2.40 2023 0.854 0.294 0.230 0.605 81% 8.93 3.08 2.40 2024 0.854 0.288 0.228 0.605 81% 9.04 3.05 2.42 2025 0.854 0.284 0.228 0.605 81% 9.15 3.04 2.44 2026 0.854 0.280 0.227 0.605 81% 9.28 3.05 2.47 2027 0.854 0.278 0.226 0.605 81% 9.42 3.07 2.50 2028 0.854 0.278 0.226 0.605 81% 9.55 3.11 2.53 2029 0.854 0.278 0.226 0.605 81% 9.69 3.15 2.57 2030 0.854 0.278 0.226 0.605 81% 9.82 3.20 2.60 
PENNSYLVANIA - Emissions and ORVR Percentages

(IEE 0.86)

02468

1012

2001 2006 2011 2016 2021 2026

Emissions (tons/summer day)

0%10%20%30%40%50%60%70%80%90%100%

% PenetrationEmissions if only Stag

place, without ORVR Emissions with only Owithout Stage II controEmissions with Stage "incompatibility excess lb/1000 gal for Vacuum Emissions with Stage "excess emissionsORVR Penetration, opvehiclesORVR Penetration, opVMTORVR Penetration, opfuel dispensed

"Widespread use" date under option (c)

"Widespread use" date under option (c2)
TOTAL REFUELING EMISSIONS – Pennsylvania (Calculations assume all VA have IEE of 0.86, uncorrected) 

Grams Emitted Per Gallon Gasoline Tons Per Summer 

Calendar 

Year 

Stage II 

Controls 

Only 

ORVR 

Only 

Stage II 

with ORVR, 

No IEE 

Stage II with 

ORVR, IEE 

% Decrease 

from 

Uncontrolled 

Emissions

Stage II 

Controls Only 

ORVR 

Only 

Stage II with 

ORVR, No 

IEE 

2001 1.052 2.691 0.943 0.980 68% 3.68 9.40 3.29 2002 1.052 2.499 0.886 0.943 69% 3.77 8.96 3.18 2003 1.065 2.316 0.831 0.912 71% 3.91 8.51 3.06 2004 1.065 2.088 0.764 0.868 72% 4.01 7.86 2.88 2005 1.065 1.842 0.692 0.821 74% 4.11 7.11 2.67 2006 1.065 1.592 0.618 0.773 75% 4.20 6.28 2.44 2007 1.065 1.368 0.552 0.731 77% 4.30 5.52 2.23 2008 1.065 1.203 0.503 0.700 78% 4.40 4.96 2.08 2009 1.065 1.041 0.455 0.669 79% 4.49 4.39 1.92 2010 1.065 0.896 0.413 0.642 79% 4.59 3.86 1.78 2011 1.065 0.774 0.377 0.620 80% 4.69 3.40 1.66 2012 1.065 0.670 0.346 0.601 81% 4.78 3.01 1.55 2013 1.065 0.584 0.321 0.585 81% 4.88 2.67 1.47 2014 1.065 0.516 0.301 0.573 82% 4.97 2.41 1.40 2015 1.065 0.463 0.285 0.563 82% 5.07 2.20 1.36 2016 1.065 0.420 0.272 0.556 82% 5.17 2.03 1.32 2017 1.065 0.384 0.262 0.550 82% 5.26 1.90 1.29 2018 1.065 0.364 0.256 0.547 82% 5.36 1.83 1.29 2019 1.065 0.337 0.248 0.542 83% 5.46 1.73 1.27 2020 1.065 0.314 0.241 0.539 83% 5.55 1.64 1.26 2021 1.065 0.296 0.236 0.536 83% 5.65 1.57 1.25 2022 1.065 0.281 0.232 0.534 83% 5.75 1.52 1.25 2023 1.065 0.271 0.229 0.532 83% 5.84 1.49 1.25 2024 1.065 0.265 0.227 0.532 83% 5.94 1.47 1.26 2025 1.065 0.258 0.225 0.531 83% 6.03 1.46 1.27 2026 1.065 0.253 0.223 0.530 83% 6.13 1.46 1.28 2027 1.065 0.250 0.222 0.530 83% 6.23 1.46 1.30 2028 1.065 0.249 0.222 0.531 83% 6.32 1.48 1.32 2029 1.065 0.246 0.221 0.531 83% 6.42 1.48 1.33 2030 1.065 0.246 0.221 0.531 83% 6.52 1.50 1.35 
D-1 

Appendix D 

ORVR WIDESPREAD USE ANALYSIS 

Widespread Use Dates – Definition (c) Versus Definition (c2) 

The U.S. EPA’s Draft Stage II Vapor Recovery Options Paper (February 7, 2006) (hereinafter 

“Options Paper”) outlines a number of possible options for defining when Onboard Refueling 

Vapor Recovery (ORVR) systems are in widespread use and therefore when states may 

terminate their Stage II Vapor Recovery Programs. In its Options Paper, EPA has indicated it is 

likely to settle either on Definition (c) or Definition (c2) for widespread use determinations, and 

of the two, the Definition (c2) approach is EPA’s preferred alternative. 

The following provides a short summary of each of these definitions: 

Definition (c) – Widespread use of ORVR is achieved in a given state or nonattainment area 

when VOC emissions (tons per summer day1

) under an ORVR-only scenario equal VOC 

emissions under a Stage II-only scenario. 

Definition (c2) – Widespread use of ORVR is achieved in a given state or nonattainment area 

when VOC emissions (tons per summer day) under a prospective ORVR-only scenario equal 

VOC emissions under a real world combination scenario in which (1) Stage II controls are in 

place, (2) both ORVR and non-ORVR equipped vehicles are fueling at Stage II equipped 

stations, and (3) fueling of the ORVR equipped vehicles is creating incompatibility excess 

emissions (IEE) between the two systems. 

As explained below, the widespread use date under Definition (c2) typically occurs several years 

after the date under Definition (c). 

Explanation of Difference in Dates for Achieving Widespread Use

The EPA Options Paper included an analysis of widespread use scenarios for three states: 

Massachusetts, Vermont, and New Hampshire. Appendix C of the Options Paper summarizes the 

data and presents charts to illustrate the scenarios for the three states. Using the Massachusetts 

example, widespread use under Definition (c) occurs about the year 2010. In contrast, 

widespread use under Definition (c2) occurs five years later, about the year 2015. As a first step 

towards understanding why there is such a difference, we provide the following explanation, 

focused on the Massachusetts chart given on page 6 of Appendix C of the EPA Options Paper. 

 

1

 Summer day is selected for two reasons. First, it represents the worst case emissions scenario where, due to 

warmer weather, gasoline vaporization is at a maximum. Second, because Stage II Vapor Recovery is an ozone 

reduction strategy, it is appropriate to examine the effect of removal of an ozone precursor control measure on a day 

when ozone is more likely to be at a higher concentration.
D-2 

Green Line (with Triangles) – Emissions with Stage II, ORVR, and IEE 

The green line marked with triangles represents the present day real world combination scenario 

outlined in Definition (c2). At the point Stage II is removed, the green line ceases to exist and 

the new real world scenario is the blue line marked with diamonds. 

Blue Line (with Diamonds) – Emissions with Only ORVR Requirements in Place 

Until Stage II is removed, the blue line (diamonds) is not a real world scenario. The present-day 

value of the blue line is that it illustrates how an ORVR program by itself becomes increasingly 

effective at reducing emissions over time as ORVR-equipped vehicles replace non-ORVR 

vehicles in the fleet. As stated above, the blue line (diamonds) replaces the green line (triangles) 

as the real world scenario once Stage II is removed. 

Violet Line (with Squares) – Emissions with Only Stage II Controls in Place 

The violet line marked with squares ceased to represent real world conditions back in the 1990s 

when the first ORVR-equipped vehicles entered the fleet. In the Massachusetts chart, which 

shows a time span from 2001 out to about 2030, this line never reflects real world conditions. 

The continual upward slope of the violet line over time illustrates that because gasoline 

consumption (therefore gasoline throughput from service stations) is continually increasing, 

emissions from the collective Stage II systems is also continually increasing. 

Intersection of the Blue and the Violet Lines (Definition (c)) 

This is an intersection of two non-real world scenarios. In one scenario (blue line with 

diamonds), Stage II controls never existed but instead ORVR was implemented. In the opposite 

scenario (violet line with squares), Stage II controls were implemented but ORVR never existed. 

Emissions Implications of Definition (c) 

According to this analysis, when widespread use is achieved and Stage II controls are removed, 

the green line (triangles) ceases to reflect real world conditions, and instead the blue line 

(diamonds) reflects the real world. In the Massachusetts example, in 2010 (widespread use date 

under Definition (c)), the blue line emissions (the new real world of ORVR only and no Stage II) 

are 6.84 tons per summer day. The green line (real world prior to removal of Stage II) emissions 

in 2010 are 4.08 tons per summer day. Thus, by removing Stage II controls in 2010, there is an 

emissions increase of 2.76 tons of VOC per day.2

 These are the excess emissions caused by 

refueling the remaining non-ORVR equipped vehicles without Stage II controls.3

Emissions Implications of Definition (c2) 

Continuing with the Massachusetts example, in 2015 the blue line (diamonds) emissions are 3.65 

tons per summer day and the green line (triangles) emissions are 3.86 tons per summer day. By 

 

2

 Removal of Stage II Vapor Recovery as a control measure in an ozone nonattainment area would require EPA 

approval of a State Implementation Plan (SIP) revision. According to § 110(l) of the Clean Air Act, the 

Administrator shall not approve a SIP revision if the revision would interfere with any applicable requirement 

concerning attainment and reasonable further progress. Therefore, if removal of Stage II Vapor Recovery resulted 

in a VOC emissions increase on the order of several tons per day during the ozone season, it may not be an 

approvable SIP revision. 

3

 The emissions would actually be slightly higher if not for the benefit achieved by eliminating the incompatibility 

excess emissions associated with refueling ORVR equipped vehicles with vacuum assisted Stage II Vapor Recovery 

equipment. 
D-3 

removing Stage II in 2015, there is a net emissions benefit of 0.21 tons per day. At this point, 

there is a great enough penetration of ORVR equipped vehicles into the fleet for ORVR to more 

than offset the emissions benefit from continuing to utilize Stage II controls for capturing 

emissions from the relatively small residual population of non-ORVR equipped vehicles. 

Conclusion 

Definition (c2) is based on real world conditions and has no emissions consequences associated 

with the termination of Stage II Programs as compared to Definition (c). 
APPENDIX E 

EFFECT OF INCOMPATIBILITY EXCESS EMISSIONS FACTOR 

 ON 

ORVR WIDESPREAD USE DATE 

FOR 

METROPOLITAN ATLANTA, GEORGIA 
Metropolitan Atlanta, GA “Definition c2” Widespread Use Dates - Varying IEE Scenarios 

Emissions (Tons per Summer Day) 

Stage II with ORVR with IEE Factor as Indicated Calendar 

Year ORVR 

Only IEE=0.09 IEE=0.33 IEE=0.42 IEE=0.55 IEE=0.72 IEE=0.86 

2010 6.94 3.66 4.27 4.50 4.83 5.27 5.62 

2011 6.03 3.54 4.19 4.44 4.79 5.25 5.63 

2012 5.27 3.44 4.13 4.39 4.77 5.25 5.66 

2013 4.66 3.37 4.10 4.37 4.76 5.27 5.69 

2014 4.22 3.34 4.09 4.37 4.78 5.31 5.75 

2015 3.92 3.33 4.10 4.39 4.81 5.36 5.81 

2016 3.71 3.32 4.12 4.41 4.84 5.41 5.87 

2017 3.55 3.33 4.14 4.44 4.88 5.45 5.93 

2018 3.43 3.34 4.17 4.48 4.92 5.51 5.99 

2019 3.33 3.36 4.20 4.51 4.97 5.56 6.05 

c2 Year 2019 2015 2014 2013 2013 2012 

Note: According to the supplied inputs, in the metropolitan Atlanta counties, 93.3 percent of 

Stage II systems are vacuum-assist and 6.7 percent are balance systems.