EPA420-R-99-021

Achieving Clean Air and Clean Water:

The Report of the Blue Ribbon Panel

on Oxygenates in Gasoline

September 15, 1999
TABLE OF CONTENTS

Page

CHAPTER 1. EXECUTIVE SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

CHAPTER 2. ISSUE SUMMARIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

A. Water Contamination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

I. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

II. Contamination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

III. Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

IV. Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

V. Drinking Water Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Appendix A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

B. Air Quality Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

I. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

II. Federal RFG Program: Requirements and Benefits . . . . . . . . . . . . . . . . . . . . . 22

III. The Impact on RFG if Oxygenates are Removed . . . . . . . . . . . . . . . . . . . . . . . 26

IV. Other Air Quality Considerations for Oxygenates . . . . . . . . . . . . . . . . . . . . . . 30

V. Wintertime Oxyfuel Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Appendix B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

C. Prevention, Treatment, and Remediation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

I. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

II. Sources and Trends of Water Quality Impacts . . . . . . . . . . . . . . . . . . . . . . . . . 40

III. Release Prevention and Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

IV. Underground Storage Tanks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

V. Protection of Drinking Water Sources and Water Quality Management . . . . . 48

VI. Treatment of Impacted Drinking Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

VII. Remediation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

D. Fuel Supply and Cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

I. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

II. Industry Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

III. Impact of Fuel Requirement Changes on Supply . . . . . . . . . . . . . . . . . . . . . . . 66

IV. Cost Impacts of Changing Fuel Reformulations . . . . . . . . . . . . . . . . . . . . . . . . 69

Appendix D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

E. Comparing the Fuel Additives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

I. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

II. MTBE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

III. Ethanol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

IV. Other Ethers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

V. Other Alternatives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

Appendix E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

CHAPTER 3. FINDINGS AND RECOMMENDATIONS OF THE BLUE RIBBON PANEL . . . . . . . 83

Appendix A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

CHAPTER 4. DISSENTING OPINIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
TABLE OF CONTENTS (continued)

Page

LIST OF PANEL MEMBERS AND PARTICIPANTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

GLOSSARY OF TERMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
1

 Areas using RFG (2% by weight oxygen) and/or Oxyfuel (2.7% by weight Oxygen)

1

CHAPTER 1. EXECUTIVE SUMMARY

The Federal Reformulated Gasoline Program (RFG) established in the Clean Air Act Amendments of

1990, and implemented in 1995, has provided substantial reductions in the emissions of a number of air

pollutants from motor vehicles, most notably volatile organic compounds (precursors of ozone), carbon

monoxide, and mobile-source air toxics (benzene, 1,3-butadiene, and others), in most cases resulting in

emissions reductions that exceed those required by law. To address its unique air pollution challenges,

California has adopted similar, but more stringent requirements for California RFG. In addition, areas in

both California and elsewhere in the nation that have not attained the National Ambient Air Quality

Standard for carbon monoxide are required in the Act to implement the Wintertime Oxyfuel program. 

The Clean Air Act requires that RFG contain 2 percent oxygen by weight. Over 85 percent of RFG

contains the oxygenate methyl tertiary butyl ether (MTBE) and approximately 8 percent contains ethanol

-- a domestic fuel-blending stock made from grain and potentially from recycled biomass waste. The Act

requires Wintertime Oxyfuel to contain 2.7 percent oxygen by weight. 

There is disagreement about the precise role of oxygenates in attaining the RFG air quality benefits,

although there is evidence from the existing program that increased use of oxygenates results in reduced

carbon monoxide emissions, and it appears that additives contribute to reductions in aromatics in fuels

and related air benefits. It is possible to formulate gasoline without oxygenates that can attain similar air

toxics reductions, but it is less certain that given current Federal RFG requirements all fuel blends

created without oxygenates could maintain the benefits provided today by oxygenated RFG.

At the same time, the use of MTBE in the program has resulted in growing detections of MTBE in

drinking water, with between 5 percent and 10 percent of community drinking water supplies in high

oxygenate use areas1

 showing at least detectable amounts of MTBE. The great majority of these

detections to date have been well below levels of public health concern, with approximately one percent

rising to levels above 20 parts per billion (ppb). Detections at lower levels have, however, raised

consumer taste and odor concerns that have caused water suppliers to stop using some water supplies and

to incur costs of treatment and remediation. Private wells have also been contaminated, and these wells

are less protected than public drinking water supplies and not monitored for chemical contamination. 

There is also evidence of contamination of surface waters, particularly during summer boating seasons.

The major source of groundwater contamination appears to be releases from underground gasoline

storage systems. These systems have been upgraded over the last decade, likely resulting in reduced risk

of leaks. However, approximately 20 percent of the storage systems have not yet been upgraded, and

there continue to be reports of releases from some upgraded systems, due to inadequate design,

installation, maintenance, and/or operation. In addition, many fuel storage systems (e.g. farms, small

above-ground tanks) are not currently regulated by the U.S. Environmental Protection Agency. Beyond

groundwater contamination from underground storage tank (UST) sources, the other major sources of

water contamination appear to be small and large gasoline spills to ground and surface waters, and

recreational water craft -- particularly those with older motors -- releasing unburned fuel to surface

waters.
2

The Blue Ribbon Panel

In response to the growing concerns from State and local officials and the public, U.S. EPA

Administrator Carol M. Browner appointed a Blue Ribbon Panel in November 1998, to investigate the air

quality benefits and water quality concerns associated with oxygenates in gasoline, and to provide

independent advice and recommendations on ways to maintain air quality while protecting water quality. 

The Panel members consisted of leading experts from the public health and scientific communities,

automotive fuels industry, water utilities, and local and State governments. The Panel was charged to: 

(1) examine the role of oxygenates in meeting the nation’s goal of clean air; (2) evaluate each product’s

efficiency in providing clean air benefits and the existence of alternatives; (3) assess the behavior of

oxygenates in the environment; (4) review any known health effects; and (5) compare the cost of

production and use and each product’s availability -- both at present and in the future. Further, the Panel 

studied the causes of ground water and drinking water contamination from motor vehicle fuels, and

explored prevention and cleanup technologies for water and soil. The Panel was established under

EPA’s Federal Advisory Committee Act’s Clean Air Act Advisory Committee, a policy committee

established to advise the U.S. EPA on issues related to implementing the CAAA of 1990. It met six

times from January - June, 1999, heard presentations in Washington, the Northeast, and California about

the benefits and concerns related to RFG and the oxygenates; gathered the best available information on

the program and its effects; identified key data gaps; and evaluated a series of alternative

recommendations based on their effects on:

6 air quality

6 water quality

6 stability of fuel supply and cost

This report consists of five issue summaries: water contamination; air quality benefits; prevention;

treatment and remediation; fuel supply and cost; and comparing the fuel additives. In addition, this

report contains the findings and recommendations of the Panel, dissenting opinions, list of Panel

members, references, and glossary of terms. 

The Findings and Recommendations of the Blue Ribbon Panel

Findings

Based on its review of the issues, the Panel made the following overall findings:

& The distribution, use, and combustion of gasoline poses risks to our environment and

public health. 

& RFG provides considerable air quality improvements and benefits for millions of US

citizens.

& The use of MTBE has raised the issue of the effects of both MTBE alone and MTBE in

gasoline. This Panel was not constituted to perform an independent comprehensive

health assessment and has chosen to rely on recent reports by a number of state, national,

and international health agencies. What seems clear, however, is that MTBE, due to its

persistence and mobility in water, is more likely to contaminate ground and surface water

than the other components of gasoline.
3

& MTBE has been found in a number of water supplies nationwide, primarily causing

consumer odor and taste concerns that have led water suppliers to reduce use of those

supplies. Incidents of MTBE in drinking water supplies at levels well above EPA and

state guidelines and standards have occurred, but are rare. The Panel believes that the

occurrence of MTBE in drinking water supplies can and should be substantially reduced.

& MTBE is currently an integral component of the U.S. gasoline supply both in terms of

volume and octane. As such, changes in its use, with the attendant capital construction

and infrastructure modifications, must be implemented with sufficient time, certainty,

and flexibility to maintain the stability of both the complex U. S. fuel supply system and

gasoline prices. 

The following recommendations are intended to be implemented as a single package of actions designed

to simultaneously maintain air quality benefits while enhancing water quality protection and assuring a

stable fuel supply at reasonable cost. The majority of these recommendations could be implemented by

federal and state environmental agencies without further legislative action, and we would urge their rapid

implementation. We would, as well, urge all parties to work with Congress to implement those of our

recommendations that require legislative action.

Recommendations to Enhance Water Protection

Based on its review of the existing federal, state and local programs to protect, treat, and remediate water

supplies, the Blue Ribbon Panel makes the following recommendations to enhance, accelerate, and

expand existing programs to improve protection of drinking water supplies from contamination. 

Prevention

1. EPA, working with the states, should take the following actions to enhance significantly

the Federal and State Underground Storage Tank programs:

a. Accelerate enforcement of the replacement of existing tank systems to conform

with the federally-required December 22, 1998 deadline for upgrade, including,

at a minimum, moving to have all states prohibit fuel deliveries to non-upgraded

tanks, and adding enforcement and compliance resources to ensure prompt

enforcement action, especially in areas using RFG and Wintertime Oxyfuel.

b. Evaluate the field performance of current system design requirements and

technology and, based on that evaluation, improve system requirements to

minimize leaks/releases, particularly in vulnerable areas (see recommendations

on Wellhead Protection Program in 2. below).

c. Strengthen release detection requirements to enhance early detection,

particularly in vulnerable areas, and to ensure rapid repair and remediation.

d. Require monitoring and reporting of MTBE and other ethers in groundwater at

all UST release sites.

e. Encourage states to require that the proximity to drinking water supplies, and the

potential to impact those supplies, be considered in land-use planning and

permitting decisions for siting of new UST facilities and petroleum pipelines.
4

f. Implement and/or expand programs to train and license UST system installers

and maintenance personnel.

g. Work with Congress to examine and, if needed, expand the universe of regulated

tanks to include underground and aboveground fuel storage systems that are not

currently regulated yet pose substantial risk to drinking water supplies.

2. EPA should work with its state and local water supply partners to enhance

implementation of the Federal and State Safe Drinking Water Act programs to:

a. Accelerate, particularly in those areas where RFG or Oxygenated Fuel is used,

the assessments of drinking water source protection areas required in Section

1453 of the Safe Drinking Water Act, as amended in 1996.

b. Coordinate the Source Water Assessment program in each state with federal and

state Underground Storage Tank Programs using geographic information and

other advanced data systems to determine the location of drinking water sources

and to identify UST sites within source protection zones.

c. Accelerate currently-planned implementation of testing for and reporting of

MTBE in public drinking water supplies to occur before 2001.

d. Increase ongoing federal, state, and local efforts in Wellhead Protection Areas

including:

6 enhanced permitting, design, and system installation requirements for

USTs and pipelines in these areas;

6 strengthened efforts to ensure that non-operating USTs are properly

closed;

6 enhanced UST release prevention and detection; and

6 improved inventory management of fuels.

3. EPA should work with states and localities to enhance their efforts to protect lakes and

reservoirs that serve as drinking water supplies by restricting use of recreational water

craft, particularly those with older motors.

4. EPA should work with other federal agencies, the states, and private sector partners to

implement expanded programs to protect private well users, including, but not limited to:

a. A nationwide assessment of the incidence of contamination of private wells by

components of gasoline as well as by other common contaminants in shallow

groundwater;

b. Broad-based outreach and public education programs for owners and users of

private wells on preventing, detecting, and treating contamination; and

c. Programs to encourage and facilitate regular water quality testing of private

wells.
5

5. Implement, through public-private partnerships, expanded Public Education programs at

the federal, state, and local levels on the proper handling and disposal of gasoline.

6. Develop and implement an integrated field research program into the groundwater

behavior of gasoline and oxygenates, including:

a. Identifying and initiating research at a population of UST release sites and

nearby drinking water supplies including sites with MTBE, sites with ethanol,

and sites using no oxygenate; and

b. Conducting broader, comparative studies of levels of MTBE, ethanol, benzene,

and other gasoline compounds in drinking water supplies in areas using primarily

MTBE, areas using primarily ethanol, and areas using no or lower levels of

oxygenate.

Treatment and Remediation

7. EPA should work with Congress to expand resources available for the up-front funding

of the treatment of drinking water supplies contaminated with MTBE and other gasoline

components to ensure that affected supplies can be rapidly treated and returned to

service, or that an alternative water supply can be provided. This could take a number of

forms, including but not limited to:

a. Enhancing the existing Federal Leaking Underground Storage Tank Trust Fund

by fully appropriating the annual available amount in the Fund, ensuring that

treatment of contaminated drinking water supplies can be funded, and

streamlining the procedures for obtaining funding;

b. Establishing another form of funding mechanism which ties the funding more

directly to the source of contamination; and

c. Encouraging states to consider targeting State Revolving Funds (SRF) to help

accelerate treatment and remediation in high priority areas.

8. Given the different behavior of MTBE in groundwater when compared to other

components of gasoline, states in RFG and Oxyfuel areas should reexamine and enhance

state and federal “triage” procedures for prioritizing remediation efforts at UST sites

based on their proximity to drinking water supplies.

9. Accelerate laboratory and field research, and pilot projects, for the development and

implementation of cost-effective water supply treatment and remediation technology, and

harmonize these efforts with other public/private efforts underway.

Recommendations for Blending Fuel for Clean Air and Water

Based on its review of the current water protection programs, and the likely progress that can be made in

tightening and strengthening those programs by implementing Recommendations 1 - 9 above, the Panel

agreed broadly, although not unanimously, that even enhanced protection programs will not give

adequate assurance that water supplies will be protected, and that changes need to be made to the RFG
6

program to reduce the amount of MTBE being used, while ensuring that the air quality benefits of RFG,

and fuel supply and price stability, are maintained.

Given the complexity of the national fuel system, the advantages and disadvantages of each of the fuel

blending options the Panel considered (see Appendix A), and the need to maintain the air quality benefits

of the current program, the Panel recommends an integrated package of actions by both Congress and

EPA that should be implemented as quickly as possible. The key elements of that package, described in

more detail below, are:

& Action agreed to broadly by the Panel to reduce the use of MTBE substantially (with

some members supporting its complete phase-out), and action by Congress to clarify

federal and state authority to regulate and/or eliminate the use of gasoline additives that

threaten drinking water supplies; 

& Action by Congress to remove the current 2 percent oxygen requirement to ensure that

adequate fuel supplies can be blended in a cost-effective manner while quickly reducing

usage of MTBE; and

& Action by EPA to ensure that there is no loss of current air quality benefits.

The Oxygen Requirement

10. The current Clean Air Act requirement to require 2 percent oxygen, by weight, in RFG

must be removed in order to provide flexibility to blend adequate fuel supplies in a costeffective manner while quickly reducing usage of MTBE and maintaining air quality

benefits.

The Panel recognizes that Congress, when adopting the oxygen requirement, sought to

advance several national policy goals (energy security and diversity, agricultural policy,

etc) that are beyond the scope of our expertise and deliberations. 

The Panel further recognizes that if Congress acts on the recommendation to remove the

requirement, Congress will likely seek other legislative mechanisms to fulfill these other

national policy interests.

Maintaining Air Benefits

11. Present toxic emission performance of RFG can be attributed, to some degree, to a 

combination of three primary factors: (1) mass emission performance requirements; (2)

the use of oxygenates; and (3) a necessary compliance margin with a per gallon standard. 

In Cal RFG, caps on specific components of fuel is an additional factor to which toxics

emission reductions can be attributed.

Outside of California, lifting the oxygen requirement as recommended above may lead to

fuel reformulations that achieve the minimum performance standards required under the

1990 Act, rather than the larger air quality benefits currently observed. In addition,

changes in the RFG program could have adverse consequences for conventional gasoline

as well.
2

 The Panel is aware of the current proposal for further changes to the sulfur levels of gasoline and recognizes

that implementation of any change resulting from the Panel’s recommendations will, of necessity, need to be

coordinated with implementation of these other changes. However, a majority of the Panel considered the

maintenance of current RFG air quality benefits as separate from any additional benefits that might accrue from the

sulfur changes currently under consideration.

3

 Under §211 of the 1990 Clean Air Act, Congress provided EPA with authority to regulate fuel formulation to

improve air quality. In addition to EPA’s national authority, in §211(c)(4) Congress sought to balance the desire for

maximum uniformity in our nation’s fuel supply with the obligation to empower states to adopt measures necessary to meet

national air quality standards. Under §211(c)(4), states may adopt regulations on the components of fuel, but must demonstrate

that 1) their proposed regulations are needed to address a violation of the NAAQS and 2) it is not possible to achieve the desired

outcome without such changes.

The Panel recommends that Federal law be amended to clarify EPA and state authority to regulate and/or eliminate

gasoline additives that threaten water supplies. It is expected that this would be done initially on a national level to maintain

uniformity in the fuel supply. For further action by the states, the granting of such authority should be based upon a similar two

part test:

1) states must demonstrate that their water resources are at risk from MTBE use, above and beyond the risk posed by

other gasoline components at levels of MTBE use present at the time of the request.

2) states have taken necessary measures to restrict/eliminate the presence of gasoline in the water resource. 

To maximize the uniformity with which any changes are implemented and minimize impacts on cost and

fuel supply, the Panel recommends that EPA establish criteria for state waiver requests including but not

limited to: 

a. Water quality metrics necessary to demonstrate the risk to water resources and air quality metrics

(continued...)

7

Within California, lifting the oxygen requirement will result in greater flexibility to

maintain and enhance emission reductions, particularly as California pursues new

formulation requirements for gasoline. 

In order to ensure that there is no loss of current air quality benefits, EPA should seek

appropriate mechanisms for both the RFG Phase II and Conventional Gasoline programs

to define and maintain in RFG II the real world performance observed in RFG Phase I

while preventing deterioration of the current air quality performance of conventional

gasoline.2

There are several possible mechanisms to accomplish this. One obvious way is to

enhance the mass-based performance requirements currently used in the program. At the

same time, the Panel recognizes that the different exhaust components pose differential

risks to public health due in large degree to their variable potency. The Panel urges EPA

to explore and implement mechanisms to achieve equivalent or improved public health

results that focus on reducing those compounds that pose the greatest risk.

Reducing the Use of MTBE

12. The Panel agreed broadly that, in order to minimize current and future threats to drinking

water, the use of MTBE should be reduced substantially. Several members believed that

the use of MTBE should be phased out completely. The Panel recommends that

Congress act quickly to clarify federal and state authority to regulate and/or eliminate the

use of gasoline additives that pose a threat to drinking water supplies.3

 
3

 (...continued)

to ensure no loss of benefits from the federal RFG program.

b. Compliance with federal requirements to prevent leaking and spilling of gasoline.

c. Programs for remediation and response.

d. A consistent schedule for state demonstrations, EPA review, and any resulting regulation of the

volume of gasoline components in order to minimize disruption to the fuel supply system.

4

 Although a rapid, substantial reduction will require removal of the oxygen requirement, EPA should, in order

to enable initial reductions to occur as soon as possible, review administrative flexibility under existing law to allow

refiners who desire to make reductions to begin doing so.

8

Initial efforts to reduce should begin immediately, with substantial reductions to begin as

soon as Recommendation 10 above - the removal of the 2 percent oxygen requirement -

is implemented4

. Accomplishing any such major change in the gasoline supply without

disruptions to fuel supply and price will require adequate lead time - up to 4 years if the

use of MTBE is eliminated, sooner in the case of a substantial reduction (e.g. returning

to historical levels of MTBE use). 

The Panel recommends, as well, that any reduction should be designed so as to not result

in an increase in MTBE use in Conventional Gasoline areas.

13. The other ethers (e.g. ETBE, TAME, and DIPE) have been less widely used and less

widely studied than MTBE. To the extent that they have been studied, they appear to

have similar, but not identical, chemical and hydrogeologic characteristics. The Panel

recommends accelerated study of the health effects and groundwater characteristics of

these compounds before they are allowed to be placed in widespread use. 

In addition, EPA and others should accelerate ongoing research efforts into the

inhalation and ingestion health effects, air emission transformation byproducts, and

environmental behavior of all oxygenates and other components likely to increase in the

absence of MTBE. This should include research on ethanol, alkylates, and aromatics, as

well as of gasoline compositions containing those components.

14. To ensure that any reduction is adequate to protect water supplies, the Panel recommends

that EPA, in conjunction with USGS, the Departments of Agriculture and Energy,

industry, and water suppliers, should move quickly to:

a. Conduct short-term modeling analyses and other research based on existing data

to estimate current and likely future threats of contamination;

b. Establish routine systems to collect and publish, at least annually, all available

monitoring data on:

6 use of MTBE, other ethers, and Ethanol; 

6 levels of MTBE, Ethanol, and petroleum hydrocarbons found in ground,

surface and drinking water;

6 trends in detections and levels of MTBE, Ethanol, and petroleum

hydrocarbons in ground and drinking water; 
9

c. Identify and begin to collect additional data necessary to adequately assess the

current and potential future state of contamination.

The Wintertime Oxyfuel Program

The Wintertime Oxyfuel Program continues to provide a means for some areas of the country to

come into, or maintain, compliance with the Carbon Monoxide standard. Only a few

metropolitan areas continue to use MTBE in this program. In most areas today, ethanol can and

is meeting these wintertime needs for oxygen without raising volatility concerns given the

season.

15. The Panel recommends that the Wintertime Oxyfuel program be continued (a) for as

long as it provides a useful compliance and/or maintenance tool for the affected states

and metropolitan areas, and (b) assuming that the clarification of state and federal

authority described above is enacted to enable states, where necessary, to regulate and/or

eliminate the use of gasoline additives that threaten drinking water supplies.

Recommendations for Evaluating and Learning From Experience

The introduction of reformulated gasoline has had substantial air quality benefits, but has at the same

time raised significant issues about the questions that should be asked before widespread introduction of

a new, broadly-used product. The unanticipated effects of RFG on groundwater highlight the importance

of exploring the potential for adverse effects in all media (air, soil, and water), and on human and

ecosystem health, before widespread introduction of any new, broadly-used, product.

16. In order to prevent future such incidents, and to evaluate of the effectiveness and the

impacts of the RFG program, EPA should:

a. Conduct a full, multi-media assessment (of effects on air, soil, and water) of any

major new additive to gasoline prior to its introduction;

b. Establish routine and statistically valid methods for assessing the actual

composition of RFG and its air quality benefits, including the development, to

the maximum extent possible, of field monitoring and emissions characterization

techniques to assess “real world” effects of different blends on emissions;

c. Establish a routine process, perhaps as a part of the Annual Air Quality trends

reporting process, for reporting on the air quality results from the RFG program;

and

d. Build on existing public health surveillance systems to measure the broader

impact (both beneficial and adverse) of changes in gasoline formulations on

public health and the environment.
10

Summary of Dissenting Opinion 

By Todd C. Sneller, Member

EPA Blue Ribbon Panel

The complete text of Mr. Sneller’s dissenting opinion on the Panel’s recommendation to

eliminate the federal oxygen standard for reformulated gasoline is included in Chapter 4 of this

report.

In its report regarding the use of oxygenates in gasoline, a majority of the Blue Ribbon Panel on

Oxygenates in Gasoline recommends that action be taken to eliminate the current oxygen

standard for reformulated gasoline. Based on legislative history, public policy objectives, and

information presented to the Panel, I do not concur with this specific recommendation. The basis

for my position follows:

The Panel’s report concludes that aromatics can be used as a safe and effective replacement for

oxygenates without resulting in deterioration in VOC and toxic emissions. In fact, a review of

the legislative history behind the passage of the Clean Air Act Amendments of 1990 clearly

shows that Congress found the increased use of aromatics to be harmful to human health and

intended that their use in gasoline be reduced as much as technically feasible.

The Panel’s report concludes that oxygenates fail to provide overwhelming air quality benefits

associated with their required use in gasoline. The Panel recommendations, in my opinion, do no

accurately reflect the benefits provided by the use of oxygenates in reformulated gasoline. 

Congress correctly saw a minimum oxygenate requirement as a cost effective means to both

reduce levels of harmful aromatics and help rid the air we breathe of harmful pollutants.

The Panel’s recommendation to urge removal of the oxygen standard does not fully take into

account other public policy objectives specifically identified during Congressional debate on the

1990 Clean Air Act Amendments. While projected benefits related to public health were a focal

point during the debate in 1990, energy security, national security, the environment and

economic impact of the Amendments were clearly part of the rationale for adopting such

amendments. It is my belief that the rationale behind adoption of the Amendments in 1990 is

equally valid, if not more so, today.

Congress thoughtfully considered and debated the benefits of reducing aromatics and requiring

the use of oxygenates in reformulated gasoline before adopting the oxygenate provisions in 1990. 

Based on the weight of evidence presented to the Panel, I remain convinced that maintenance of

the oxygenate standard is necessary to ensure cleaner air and a healthier environment. I am also

convinced that water quality must be better protected through significant improvements to

gasoline storage tanks and containment facilities. Therefore, because it is directly counter to the

weight of the vast majority of scientific and technical evidence and the clear intent of Congress, I

respectfully disagree with the Panel recommendation that the oxygenate provisions of the federal

reformulated gasoline program be removed from current law.
11

LYONDELL CHEMICAL COMPANY

SUMMARY OF DISSENTING REPORT

The complete text of Lyondell’s dissenting report is in Chapter 4 of this report.

While the Panel is to be commended on a number of good recommendations to improve the

current underground storage tank regulations and reduce the improper use of gasoline, the

Panel’s recommendations to limit the use of MTBE are not justified.

Firstly, the Panel was charged to review public health effects posed by the use of oxygenates,

particularly with respect to water contamination. The Panel did not identify any increased public

health risk associated with MTBE use in gasoline.

Secondly, no quantifiable evidence was provided to show the environmental risk to drinking

water from leaking underground storage tanks (LUST) will not be reduced to manageable levels

once the 1998 LUST regulations are fully implemented and enforced. The water contamination

data relied upon by the panel is largely misleading because it predates the implementation of the

LUST regulations.

Thirdly, the recommendations fall short in preserving the air quality benefits achieved with

oxygenate use in the existing RFG program. The air quality benefits achieved by the RFG

program will be degraded because they fall outside the control of EPA's Complex Model used for

RFG regulations and because the alternatives do not match all of MTBE's emission and gasoline

quality improvements. 

Lastly, the recommendations will impose an unnecessary additional cost of 1 to 3 billion dollars

per year (3 – 7 c/gal. RFG) on consumers and society without quantifiable offsetting social

benefits or avoided costs with respect to water quality in the future. 

Unfortunately, there appears to be an emotional rush to judgement to limit the use of MTBE. For

the forgoing reasons, Lyondell dissents from the Panel report regarding the following

recommendations:

• The recommendation to reduce the use of MTBE substantially is unwarranted

given that no increased public health risk associated with its use has been identified

by the Panel.

• The recommendation to maintain air quality benefits of RFG is narrowly limited to

the use of EPA's RFG Complex Model which does not reflect many of the vehicle

emission benefits realized with oxygenates as identified in the supporting panel

issue papers. Therefore, degradation of air quality will occur and the ability to

meet the Nation's Clean Air Goals will suffer under these recommendations.
12

CHAPTER 2. ISSUE SUMMARIES

In the course of its deliberations, the Blue Ribbon Panel heard from a number of experts in the field, and

reviewed a large number of analyses and reports compiled by a range of organizations and individuals on

the topics of air quality, water contamination, prevention and remediation, fuel supply and price, and

health effects (see References below). In order to guide its development and evaluation of the range of

options, and the selection of its recommended option, the Panel worked with its own staff, staff of a

number of federal agencies, and consultants assigned to it from ICF Consulting to compile the following

Issue Summaries.

These Issue Summaries are not intended to be complete reproductions of the many analyses and reports

the Panel reviewed, nor did the Panel necessarily have the charter or the expertise to conduct an entire de

novo review of all of the evidence on any one topic (e.g. health effects). Rather, these summaries are

designed to summarize all of the available information in a relatively neutral manner, capturing those

areas where the scientific and technical community have come to some conclusions about these topics,

and noting those areas where either there is not agreement, or where additional information is needed. 

For example, the Panel provides in Issue A. Water Contamination, the first systematic summary of water

contamination data from the states of Maine and California and from the U.S. Geological Survey. This

data, which emerged beginning late last year, was augmented substantially by analyses completed by

USGS, and a summary of the relevant data was presented to the Panel in April. The Panel did not,

however, conduct a detailed review of the analytic techniques, assumptions, and methods of each study,

but rather accepted them as valid efforts to attempt to characterize an emerging situation, and refers the

readers to the original studies for further detail.
5

 Areas using RFG (2% by weight oxygen) and /or Oxyfuel (2.7% by weight Oxygen).

13

A. Water Contamination

I. Introduction

There have been increasing detections of methyl tertiary butyl ether (MTBE) in ground waters and in

reservoirs. Overall, approximately 90 percent of tested waters have no detects, with remaining waters

generally exhibiting relatively low level contamination. As sources of water contamination are

identified, the behavior of oxygenates in ground water needs to be analyzed in order to understand the

extent of contamination. The following is a summary of what is known today concerning water

contamination. 

II. Contamination

A. Concentration Levels in Public and Private Wells

The use of MTBE in the RFG program has resulted in growing detections of MTBE in drinking water,

with between 5 percent and 10 percent of community drinking water supplies in high oxygenate use

areas5

 showing at least detectable amounts of MTBE. The great majority of these detections to date have

been well below levels of public health concern, with between 0.3 percent to 1.5 percent rising to levels

above 20 parts per billion (ppb). Detections at lower levels have, however, raised consumer taste and

odor concerns that have caused water suppliers to stop using some water supplies and to incur costs of

treatment and remediation. Private wells have also been contaminated and these wells are less protected

than public drinking water supplies and not monitored for chemical contamination. There is also

evidence of contamination of surface waters, particularly during summer boating seasons. A variety of

studies, summarized in Table 1, have sought to determine the extent of MTBE contamination of drinking

water sources. In addition, the USGS 12 Northeastern State Study has compiled data for MTBE levels in

community drinking water.

Although there are no nation-wide drinking water data sets from which to fully characterize MTBE

detections in the United States, a recent United States Geological Survey (USGS) report examines this

issue with respect to ambient ground water. This report assessed studies conducted between 1985 and

1995 by USGS-NAWQA (National Water Quality Assessment Program), local, State, and Federal

agencies by examining sampling data from 2,948 urban & rural, drinking water, and non-drinking water

wells. Projections from these data sets suggest that up to 7 percent of the nation's ground water resources

could potentially contain a volatile organic compound (VOC) such as MTBE at concentrations of at least

0.2 ppb. At this time it is difficult to project future trends of contamination due to the lack of time-series

data.
6

 Paul Squillace, et al., “Occurrence of the Gasoline Additive MTBE in Shallow Ground Water in Urban and

Agricultural Areas; Fact Sheet FS-114-95; U.S. Geological Survey: Rapid City, DS, 1995; Paul Squillace, et.al.,

Preliminary assessment of the occurrence and possible sources of MTBE in groundwater in the United States, 1993-

1994. Environ. Sci. Tech. 30 (5) 1721-1730, 1996.

7

 U.S. Environmental Protection Agency and United States Geological Survey, Preliminary Finding of the 12-

State MTBE/VOC Drinking Water Retrospective, 1999.

14

Table 1. Summary of Studies Examining MTBE Contamination of Drinking Water Sources

Concentration

Range (ppb)

California 

Public Water

Sources1

 (wells)

Maine 

Public Water

Sources3 (wells)

Maine 

Private Water

Sources3 (wells)4

USGS/NAWQA

Studies5

 (wells)

USGS/EPA 12

Northeastern State

Study6

 (systems)

N=5,195

MDL=5 ppb

N=793

MDL=0.1 ppb

N=946 (95% CI)

MDL=0.1 ppb

N=2,743

MDL=0.2 ppb

(censor level)

N=1,190

MDL=1 ppb7

Non-Detects ~99% ~84.1% ~84.3% ~94.7% ~92.8%

MDL - 5 ppb N/A2 ~14.6% ~12.8% ~ 4.5% ~5.0%

5-20 ppb ~0.3% ~0.9% ~1.5% ~0.4% ~1.3%

> 20 ppb ~0.3% ~0.4% ~1.5% ~0.4% ~0.9%

1

California Department of Health Services, April 22, 1999 ( www.dhs.ca.gov/ps/ddwem/chemicals/MTBE/mtbe_summary.htm). Because the

same source may be counted more than once (e.g., as both “raw” and “treated”, as with a reservoir), data from a single source have been

consolidated for purposes of counting “sources.”

2

Although there have been detects below 5 ppb, such detections are not required to be reported.

3

A.E. Smith, Analysis of MTBE data in public and private water sources sampled as part of the Maine MTBE Drinking Water Study --

Preliminary Report, October 13, 1998: Written Communication to U.S. EPA, May 20, 1999.

4

Data are available for other sources (e.g., springs and surface water). 5

P.J. Squillace, D.A. Bender, J.S. Zogorski, Analysis of USGS data on MTBE in wells sampled as part of the National Water Quality

Assessment Program, 1993-1998: Written Communication to U.S. EPA. May 20, 1999. 

6

S.J. Grady, Analysis of the Preliminary Findings of the 12-State MTBE/VOC Drinking Water Study, 1993-1998: Communication to U.S.

EPA, May 20, 1999.

7

Some samples with higher reporting levels have not been screened out.

Note: Some systems have multiple sources and the total number of sources is unknown. Systems with multiple detections are counted in the

highest reported concentration range. 

“MDL” = Minimum Detection Level.

MTBE was the second most commonly detected VOC in water from urban wells6. Due to the inadequacy

of long-term monitoring data, the extent and trends of ground and surface water contamination in the

nation are still not well known. As such, research is underway to obtain more contamination occurrence

data for ground and surface waters. An American Water Works Association Research Foundation

(AWWARF) study of the national occurrence of MTBE in sources of drinking water (i.e., rivers,

reservoirs, ground water, etc.) began in May 1999 and will continue for two years. This type of data will

document near-term impacts and provide important input for analysis to predict future contamination

trends.

B. RFG/OXY Areas Versus Non-RFG/OXY Areas 

Data from the joint USGS and U.S. Environmental Protection Agency (EPA) 12 Northeastern State

study7

 and the USGS/NAWQA study (Table 1) were analyzed to evaluate the frequency of MTBE

detections in drinking water in RFG/OXY versus non-RFG/OXY areas. Results from the USGS/EPA

Northeastern State study indicate that MTBE is detected ten times more often in drinking water from

community water systems in areas that use reformulated gasoline (RFG) or oxygenated fuels (OXY) than
8

 Stephen Grady and Michael Osinski, “Preliminary Findings of the 12-State MTBE/VOC Drinking Water

Retrospective,” presentation at the April 1999 MTBE Blue Ribbon Panel meeting.

9

 Paul Squillace, “MTBE in the Nation’s Ground Water, National Water-Quality Assessment (NAWQA)

Program Results,” presentation at the April 1999 MTBE Blue Ribbon Panel meeting.

10 Paul Squillace, “MTBE in the Nation’s Ground Water, National Water-Quality Assessment (NAWQA)

Program Results,” presentation at the April 1999 MTBE Blue Ribbon Panel meeting.

11 Paul Squillace, “Volatile Organic Compound in Untreated Ambient Groundwater of the United States, 1985

- 1995,” presentation at the April 1999 MTBE Blue Ribbon Panel meeting.

12 Stephen Grady and Michael Osinski, “Preliminary Findings of the 12-State MTBE/VOC Drinking Water

Retrospective” presentation at the April 1999 MTBE Blue Ribbon Panel meeting.

13 Paul Squillace, “Volatile Organic Compound in Untreated Ambient Groundwater of the United States, 1985

- 1995,” presentation at the April 1999 MTBE Blue Ribbon Panel meeting.

15

in non-RFG/OXY areas.8 Likewise, data from USGS/NAWQA indicates a similar detection frequency in

RFG/OXY areas (Table 2). The USGS/NAWQA study also indicates that higher levels of MTBE (>20

ppb) are 19 times more likely to be detected in RFG/OXY areas than in non-RFG/OXY areas.9

 MTBE

detections are clearly elevated in RFG/OXY areas as compared to BTEX (benzene, toluene,

ethylbenzene, and xylene) detections. 

Table 2. MTBE and BTEX Detection, RFG/OXY vs. Non-RFG/OXY Areas10

MTBE Detection

(0.2 ppb)

BTEX Detection

(0.2 ppb)

RFG/OXY Areas Using MTBE 

(480 Wells) 21% 4%

Non-RFG/OXY Areas in the

United States (2,263) 2% 2%

After normalizing for factors that affect detection frequency (i.e., gasoline stations, commercial and

industrial land use, etc.), MTBE is four to six times more likely to be detected in RFG/OXY areas than

non-RFG/OXY areas. In RFG/OXY areas, of the 50 million people dependent on ground water, 20

million use an aquifer containing at least one VOC, indicating potential vulnerability to MTBE.11

C. Co-Occurrence of MTBE and Other Gasoline Components

For co-occurring components in gasoline, preliminary data from both the USGS/EPA 12 Northeastern

State study and the USGS/NAWQA study shows that MTBE is generally detected in groundwater

samples that contain another VOC, but is not associated with BTEX detections. In USGS/EPA drinking

water samples containing MTBE, BTEX co-occurrence were only 0.3 percent, even though

approximately 44 percent of the samples contained one or more other VOCs.12 Similar results are

exhibited for USGS/NAWQA ground water samples containing MTBE, with only 13 percent of the

samples with MTBE also detecting BTEX.13
14 Office of Science and Technology Policy, National Science and Technology Council, Interagency

Assessment of Oxygenated Fuels, June 1997.

15 Komex H20 Science, Draft Investigation Report of MTBE Contamination: City of Santa Monica, Charnock

Well Field, Los Angeles, California, March 21, 1997; Geomatrix Consultants, Inc., Summary of MTBE

Groundwater Monitoring Results, Fourth Quarter 1998, Charnock Well Field Regional Assessment, Los Angeles,

California, April 1, 1999.

16 B. Hunter et al., “Impact of Small Gasoline Spills on Groundwater,” preliminary report abstract presented at

the Maine Water Conference Meeting, April 1999. 

17 J.E. Reuter et al., “Concentrations, Sources and Fate of the Gasoline Oxygenate Methyl Tert-Butyl Ether

(MTBE) in a Multiple-Use Lake,” Environmental Science and Technology 32, 3666-3672, 1998.

16

III. Sources

The most frequent sources of higher levels of ground water contamination (greater than 20 ppb)14 appear

to be releases from gasoline storage and distribution systems, although there have been reports (e.g.,

Maine) that would suggest other sources of contamination, such as small spills and improper disposal. In

reservoirs and lakes, MTBE detections, which vary seasonally, appear to be from recreational watercraft,

particularly those with older motors. More general contamination of ground and surface waters at lower

levels (usually less than 5 ppb) are primarily from storm water runoff and to a lesser degree, air

deposition, as well as from leaking tanks and accidental spills.

Specific examples of recent findings regarding the sources of ground water contamination include the

following:

a. Santa Monica, California15

Ground water contamination from LUSTs has resulted in the contamination

and closure of 9 high volume production drinking water wells (daily water

demand at approximately 6.5 million gallons per day) at levels up to 610 ppb

in the production wells, up to 17,000 ppb in regional monitoring wells, and

up to 230,000 ppb in LUST source-site monitoring wells.

b. Maine16

An automobile gasoline leak contaminated a supply well 100 feet away to a

level of 900 ppb.

c. University of California, Davis Donner Lake Study17

The use of motorized watercraft yielded concentration levels from 0.1 ppb to

12 ppb.
18 Metropolitan Water District, Methyl Tertiary Butyl Ether Monitoring Program at the Metropolitan Water

District of Southern California, monitoring program update, April 1999.

19 Office of Science and Technology Policy, National Science and Technology Council, Interagency

Assessment of Oxygenated Fuels, June 1997, pp. 2-33 – 2-35.

20 A.M. Happel et al., An Evaluation of MTBE Impacts to California Groundwater Resources, Lawrence

Livermore National Laboratory Report, UCRL-AR-130897, June 1998; A.M. Happel, B. Dooher, and E.H.

Beckenbach, “Methyl Tertiary Butyl Ether (MTBE) Impacts to California Groundwater,” presentation at the March

1999 MTBE Blue Ribbon Panel meeting; Salanitro, J.P., “Understanding the Limitations of Microbial Metabolism

of Ethers Used as Fuel Octane Enhancers,” Curr. Opin. Biotechnol. 6: 337-340, 1995.

21 Paul Squillace et al., “Review of the Environmental Behavior and Fate of Methyl Tertiary-Butyl Ether,”

Environ. Tox. Chem, 1997; UC Davis Report, Transport and Fate Modeling of MTBE in Lakes and Reservoirs,”

Stephen A. McCord and Geoffrey S., Schladow.

17

d. Metropolitan Water District of Southern California Monitoring Program18 

A monthly monitoring program (January 1997 to present) at six surface

water reservoirs resulted in concentrations as high as 29 ppb during summer

boating months. 

e. OSTP Report19

Storm water runoff exhibited concentrations of 0.2 - 8.7 ppb in 7

percent of samples tested in 16 cities from 1991 to 1995. Based

on modeled air concentrations, concentrations in rainwater are

predicted to range from less than 1 ppb to 3 ppb.

IV. Behavior

A. MTBE

In ground water, MTBE is more soluble, does not adsorb as readily to soil particles, biodegrades less

rapidly, and thus moves more quickly than other components of gasoline (i.e., BTEX).20 In surface

water, volatilization of MTBE at the air-water interface is a significant contributor to decreased

concentrations of MTBE.21 

Much of MTBE’s behavior is dependent upon the nature of the release, whether the release source is

point or non-point, its geologic settings, and environmental and microbial factors. In studies to date, in

situ biodegradation of MTBE has been minimal or limited at best, which is significantly less (by at least

one order of magnitude) when compared to benzene. 

B. Ethanol

Ethanol is extremely soluble in water and, based on theory, should travel at about the same rate as

MTBE. Ethanol is not expected, however, to persist in ground water due to ethanol’s ability to

biodegrade easily. In fact, laboratory research findings suggest that ethanol may inhibit the
22 H.X., Corseuil et al., “The Influence of the Gasoline Oxygenate Ethanol on Aerobic and Anaerobic BTX

Biodegradation,” Wat. Res., 1998, 32, 2065-2072.; C.S. Hunt et al., “Effect of Ethanol on Aerobic BTX

Degradation Papers from the Fourth International In Situ and On-Site Bioremediation Symposium,” Battelle Press,

April-May 1997, pp. 49-54.

23 Michael Kavanaugh and Andrew Stocking, “Evaluation of the Fate and Transport of Ethanol in the

Environment,” November, 1998. Presentation at the May 1999 MTBE Blue Ribbon Panel. [Based on Malcome

Pirnie, Inc. Evaluation of the Fate and Transport of Ethanol in the Environment (Oakland, CA, 1998.)]

24 H.X. Corseuil and P.J.J. Alvarez, “Natural Bioremediation Perspective for BTX-Contaminated Groundwater

in Brazil,” Wat. Sci. Tech., 1996, 35, 9-16.

25 EPA analytical methods are limited for ethanol analysis providing only ppm range detection limits.

26 U.S. Environmental Protection Agency, Office of Water, Drinking Water Advisory: Consumer Acceptability

Advice and Health Effects Analysis on Methyl Tertiary-Butyl Ether (MTBE), December 1997.

18

biodegradation of BTEX because the microbes preferentially metabolize ethanol before BTEX.22

Qualitative and quantitative characterizations of ethanol biodegradation under field conditions have not

been done to date. In one hypothetical analysis presented to the Panel, the addition of ethanol to gasoline

was estimated to extend BTEX plumes by 25 percent to 40 percent.23 Additionally, a study in Brazil

indicated that, high ethanol concentrations in ground water (greater than 2 percent) enhanced the

solubilization and migration of BTEX.24 No national monitoring of ethanol in ground water, surface

water or drinking water has been completed at this time.25 

V. Drinking Water Standards

A. Drinking Water Advisory

In certain situations, either the public’s concern about potential contamination, or water supply officials’

concerns about the taste and odor effects of MTBE contamination, or both, has affected the ability of

local authorities to rely on their water supplies for drinking water. For example, South Lake Tahoe,

California water officials recently closed 13 wells due to the proximity of MTBE plumes to its drinking

water wells. 

The U.S. Environmental Protection Agency’s Office of Water has established a drinking water advisory26

level of 20 to 40 ppb as a guidance for State and local authorities, based on taste and odor concerns. This

guidance suggests control levels for taste and odor acceptability and also provides a large margin of

safety against any potential adverse health effects. The advisory levels enable water suppliers to easily

assess if their drinking water is likely to be acceptable to consumers. The advisory also recognizes that

some members of the population may detect it below this range. However, as indicated in table 3, states

have established different guidelines and standards based on differing interpretations of the data

concerning the taste and odor thresholds and health effect studies for MTBE. 

In addition, EPA has proposed a revised Unregulated Contaminant Monitoring Rule, which would

require large water systems (serving more than 10,000 persons) and a representative sample of small- and

medium-sized water systems (serving fewer than 10,000 persons) to monitor and report MTBE levels. 

This program is scheduled to take effect in January 2001. Under this regulation, the majority of public
27 Water suppliers are required to monitor for volatile organic compounds and MTBE can be analyzed by the

same analytical methods and therefore could be included along with scheduled volatile organic compound sampling.

19

groundwater supply wells will still not be monitored for MTBE.27 The availability of Consumer

Confidence Reports will notify the public of what contaminants are found in drinking water. Increasing

numbers of consumers may find the water unacceptable if they are aware of MTBE’s presence. 

Private wells are not subject to monitoring under the Safe Drinking Water Act, but are left to the

discretion of the State. Therefore, private well owners rarely have routine monitoring for either bacterial

or chemical contamination. Private wells are typically more vulnerable than public wells due to

differences in wellhead construction. Specifically, these wells typically draw from shallow groundwater,

which is more vulnerable to impacts from surface contamination. 

B. State Guidelines and Action Levels

As Table 3 indicates, a number of States have established drinking water guidelines and action levels. 

Currently, four States have primary drinking water standards, three States have enforceable guidelines,

and 12 States either have an MTBE guideline or action level in place. Figure A1, located in Appendix A,

contains a map illustrating these various State standards. 

Table 3. State Drinking Water Standards, Guidelines, and Action Levels

States with Primary Drinking Water Standards

(health-based)

& Maine (35 ppb) 

& New Jersey (70 ppb) 

& New York (50 ppb) 

& South Carolina (20-40 ppb)

State with a Secondary Standard (aesthetic) & California (5 ppb); enforceable

States with Enforceable Guidelines & Michigan (240 ppb); health-based

& West Virginia (20-40 ppb); EPA Advisory

States with a Guideline or Action Level in Place

& Arizona (35 ppb); health-based

& California (13 ppb); health-based

& Connecticut (70 ppb); health-based

& Illinois (70 ppb); health-based 

& Kansas (20-40 ppb); EPA Advisory

& Maryland (10 ppb); aesthetically-based

& Massachusetts (70 ppb); health-based

& New Hampshire (15 ppb); aesthetically based

& Pennsylvania (20-40 ppb); EPA Advisory

& Rhode Island (20-40 ppb); EPA Advisory

& Vermont (40 ppb); EPA Advisory

& Wisconsin (60 ppb); health-based

Source: U.S. Environmental Protection Agency.
20

National Primary Drinking Water Standards, as defined by the Safe Drinking Water Act (SDWA), must

be health-based. Although standards can be developed at the Federal level based on taste and odor, such

standards are secondary and non-enforceable. Currently, the Drinking Water Advisory serves only as a

national guidance level for aesthetic effects that EPA recommends for drinking water. Due to

uncertainties in the health effects database, gaps in characterizing national occurrence, and significant

variability among health study methodologies, EPA does not have sufficient information to establish an

enforceable health-based standard at this time.
FL

WV

WA

OR

 ID

MT

WY

ND

SD

NE IA

MN

WI

 IL IN

OH

MO KSHA (20-40)

CO

UT

NV

CA

AZ NM OK AR

KY

VA

TX

Act

GA AL

SC

 TN NC

MI

MS

LA

Action 

Stand

HA (40)

Action Level (13)Sec. Std (5) enf.

Interim Standard MC (20-40)

 PAHA (20-40)

DE

NJ

NY

VT

NH

M

MD

Standard (35)

MA

CT 

Standard(50)

Guideline (240) enf.Aesthetic guideline (20-40)

Guideline (70)

Guideline (70)

HA (20-40) enf.

Guideline (60)

Drinking Water Regulations and Guidelines for MTBE (ug/L)U.S. EPA, June 1999

* Guidelines and Action Levels are often interchangeable (depending on the State)

HA -- Health AdvisoryEnf. - EnforceableMCLG - Maximum Contaminant Level Goal

RI

Guideline (35)

Source: U.S. Environmental Protection Agency

Appendix A

Figure A1
28 National Research Council (NRC), Ozone-Forming Potential of Reformulated Gasoline, May 1999.

29 U.S. Environmental Protection Agency, Regulatory Impact Analysis, 59 FR 7716, Docket No. A-92-12,

1993.

30 Refinery Reporting Data and RFG Survey Association Data. Data on gasoline properties contained in this

Issue Summary are derived from two primary sources. The RFG reporting data represent data submitted by the

universe of RFG producers or importers. The RFG survey data are derived from a carefully planned statistical

(continued...)

22

B. Air Quality Benefits

I. Introduction

The Federal and California reformulated gasoline (RFG) programs have significantly improved air

quality by reducing emissions of toxics and lowering the ozone forming potential through reductions in

volatile organic compound (VOC) and oxides of nitrogen (NOx). In general, these programs have

resulted in greater emission reductions than statutorily required. 

II. Federal RFG Program: Requirements and Benefits

A. Summary of RFG Requirements and Benefits

Ozone and air toxic levels in this nation have decreased substantially in recent years as a result of the

Clean Air Act’s implementation. There are over 30 areas, however, that are still in nonattainment with

the current ozone standard. The results of emissions tests, tunnel studies, and remote sensing of tail pipe

exhaust indicate that RFG usage can cause a decrease in both the exhaust and evaporative emissions from

motor vehicles.28 Based on separate cost effectiveness analyses conducted by both the U.S.

Environmental Protection Agency (EPA) and the State of California, when compared to all available

control options, RFG is a cost-effective approach to reducing ozone precursors such as VOCs and NOx.

29

Although there is no National Ambient Air Quality Standard for toxics, a number of provisions of the

Clean Air Act require reductions in toxics emissions, and Federal RFG has contributed to these

reductions.. 

The RFG program, mandated under the 1990 Clean Air Act Amendments, requires changes in motor fuel

formulation which result in decreased vehicle emissions for areas in the U.S. with significant low-level

ozone pollution, otherwise known as smog. These areas represent about 30 percent of U.S. gasoline

consumption. The program requires reductions relative to a 1990 fuel baseline in levels of NOx, toxics,

and VOC emissions and also requires a minimum level of oxygen and limits the maximum benzene level. 

The emissions performance of fuels relative to 1990 is evaluated using a linear regression model, referred

to as the “complex model,” which was developed using thousands of emissions tests relating fuel

properties to emissions performance. To certify a fuel as RFG, a fuel manufacturer measures the eight

relevant physical and chemical properties of the fuel, enters those results into the complex model, and the

model determines the percent reduction in NOx, VOC, and toxics, relative to 1990, for that fuel. Phase I

of the program began in 1995. Phase II, scheduled to begin on January 1, 2000, will implement more

stringent NOx, VOC and toxics reduction standards.

The best available data indicate that the RFG program has substantially reduced emissions of ozone

precursors and toxics (See Table 1). Analysis of fuel data reported by refiners for 1995 through 1998

indicates that emission reduction benefits exceeded the standards for VOCs, NOx, and toxics.30 Toxics
30 (...continued)

sampling of retail stations in various RFG cities. The survey plan is designed to estimate average gasoline

properties for a given area over a specific time period with a high degree of statistical confidence. 

The calculation of VOC, NOx, and toxics reductions is based upon measured properties from these two data

sources and is calculated by the “complex model,” a regression model based upon thousands of vehicle emissions

tests. As with any model, some uncertainty exists regarding the calculated emissions reductions and their

applicability for any given fleet in any given year.

31 U.S. Environmental Protection Agency bar charts reflect survey data collected from 19,000 samples during

1998. Data from RFG Survey Association.

32 U.S. Environmental Protection Agency, National Air Quality and Emissions Trends Report, 1995.

33 NESCAUM, Relative Cancer Risk of Reformulated Gasoline and Conventional Gasoline Sold in the

Northeast, August 1998.

23

reductions in particular were substantially greater than the standard (an over 33 percent reduction versus

a 17 percent requirement). (Refer to Figures B1 through B3 in this Issue Summary’s Appendix).31 In

addition, ambient monitoring data also suggest that the RFG program is working. The EPA’s 1995 Air

Quality Trends report, which coincides with the first year of the RFG program, shows a median reduction

of 38 percent in ambient benzene and significant decreases in other vehicle-related VOC concentrations

in RFG areas.32 No other control action could have accounted for such a substantial decrease in benzene

levels. 

In 1998, Northeast States for Coordinated Air Use Management (NESCAUM) conducted an assessment

of the toxicity of conventional gasoline (CG) versus RFG sold in the Northeast. This study33 focused on

six toxic air pollutants [benzene, 1,3-butadiene, acetaldehyde, polycyclic organic matter (POM),

formaldehyde, and MTBE]. A modified version of the complex model, incorporating MTBE emission

rates, was used to compare differences in predicted emissions between composited average RFG and

conventional fuel types sold in the Northeast. While emissions estimated by the complex model may not

accurately represent actual emissions from the motor vehicle fleet, it does provide a means of

establishing relative effects of fuel composition on emissions. Relative cancer potencies were assigned

to the six compounds to compare carcinogenicity among fuel types. This study concluded that Phase I

RFG (in 1996) “served to reduce cancer risk associated with gasoline vapors and automobile exhaust . . .

by 12 percent. . . .” and that Phase II RFG would “reduce the public cancer risk . . . by 20 percent. . . .” 

This report also noted that “since the cancer potency of MTBE is significantly less than that of benzene,

1,3-butadiene and POM, its presence in RFG at 10 percent by volume tends to dilute other carcinogens. .

. .” The National Research Council (NRC) report also stated that the most significant advantage of

oxygenates in fuel appears to be displacement of some air toxics (e.g., benzene from RFG). For

additional information on typical fuels and standards, refer to Table B1 in Appendix B.
24

Table B1. Typical Fuels and Standards

Fuel Parameter

Conventional

Gasoline

Pre-RFG

Federal RFG Phase I Federal RFG Phase II California RFG

Actual1

(Summer)

Complex

Avg. Std. Actual AveragingStandard Actual AveragingStandard

Reid Vapor

Pressure (psi) 8.7/7.8 7.9/7.0 (8.0/7.1)2 (6.7) 6.8 (6.8)

Sulfur (ppm) 339 190 (285) (150) 20 30

Oxygen (wt%) <0.5 2.26 2.1 min 2.1 min 2.07 (2.0)

Aromatics (vol%) 32 26 (32) (25) 23 22

Olefins (vol%) 13 10 (10) (11) 4 4

E200 (%) 41 49 (45) (49) 51 (49)

E300 (%) 83 83 (83) (87) 89 (91)

Benzene (vol%) 1.5 0.68 0.95 max .95 max 0.55 0.8

Phase II complex model performance (% reduction from 1990 baseline) of these fuels:

VOC performance 26.1 22.1 29.8 29.9 29.6

NOx performance 5.3 1.4 6.8 14.6 14.7

Toxics performance 30.1 19.7 28.4 37.0 34.4

1

“Actual” Phase I summer (VOC-controlled) RFG properties and performance estimated from 1998 RFG Compliance Surveys. 

2

Properties listed under the Federal RFG “standards” columns in parentheses are not standards per se, but indicate the average properties a

summer fuel must have to meet the emissions performance standards. The “/” indicates “North/South” specific values. South (VOC Control Region

1) values were used in performance comparisons.

As shown in Table 1, Phase II RFG, which takes effect on January 1, 2000, requires additional emission

reductions, beyond those required in Phase I. With the exception of air toxics and benzene, Phase II also

requires reductions that are greater than the actual reductions achieved in Phase I. However, for both air

toxics and benzene, the Phase II requirements, unless changed, would allow the formulation of RFG that

does not maintain the current benefits (e.g. a 22 percent reduction in toxics versus a 33 percent actual

Phase I reduction). 

Table 1. Emission Reductions Required by the RFG Program

VOCs NOx Toxics Benzene Oxygen

RFG Phase I

(1995-1999)

& Northern States: 17%

& Southern States: 37%

 1.5% 17% 1% 2.0 wt%

Actual RFG1

 Phase

I 1998

& Northern States: 21.2%

Av2

, 20.3 - 25.0% Range

& Southern States: 39.4%

Av, 38.4 - 40.3% Range

(4.9% Average;

3.8% - 7.4%

Range)

(33.2% Average;

23.7% -36.9%

Range) 0.68 % 2.0 wt%

RFG Phase II

(2000) 27% 6.8% 22% 1% 2.0 wt%

CaRFG Standards

(approx.) 29.6% 14.7 34.4 0.8 0 - 2.0 wt%

1

1998 RFG Compliance Survey Data (summer surveys), completed by the RFG Survey Association.

2"Av” = the average of the individual area results weighted by estimated gasoline volume in each area. 
25

B. CaRFG Program

Also, as shown in Table 1, the California RFG program has in place more stringent standards for its

Phase II than Federal RFG, in particular for NOx, air toxics, and benzene. The second phase in the

California RFG program (CaRFGII) is intended to ensure that benefits continue as the vehicle technology

advances and fleets turn over. CaRFGII helps automakers meet the increasingly stringent emission

standards for new vehicles. California’s program requires automakers to certify their vehicles on

CaRFGII, thus ensuring that new vehicles will be designed to meet emission standards on a fuel similar

to what the vehicles will be operated with during daily use. 

The CaRFG program is designed to ensure that different formulations of gasoline will meet the required

emissions performance levels. This is accomplished through the predictive model, which allows one to

compare the emissions performance of alternative fuel parameters against a standard set of parameters

contained in the CaRFG regulation. If the alternative formulation provides emission benefits equal to or

better than the standard formulation, emission benefits are preserved and the refiner (or fuel importer) is

allowed to market the fuel. To ensure the predictive model reflects the most recent data on the

relationship between fuel properties and emissions, the California Air Resources Board (CARB) is in the

process of updating the model to reflect newer technology vehicles. This will provide extra assurance

that the model will continue to be applicable as the vehicle fleet changes. In California, the predictive

model has been used to produce and market fuels with no oxygenates while preserving the program’s full

air quality benefits.

C. EPA 1998 Area by Area Analysis

The EPA’s Area by Area analysis of 1998 RFG Survey Data indicates that the complex model emissions

performance of RFG in Chicago and Milwaukee, while easily exceeding all Phase I performance (i.e.,

emission reduction) requirements, generally ranks low compared to other RFG areas. In order to

investigate factors influencing the performance of Chicago and Milwaukee RFG relative to RFG in other

areas, it is necessary to consider the composition of the fuels. Table B2 and an accompanying

discussion, located in the Appendix, discuss estimates of average values of the fuel properties that are

complex model inputs. The Chicago and Milwaukee properties are averages of the individual summer

survey property averages. The National Average properties were estimated by calculating an average for

each of the RFG areas surveyed during 1998, and then weighting these values by estimates of fuel

volume for each area. The National Average Reid vapor pressure (RVP) value was for VOC Control

Region 2 (North), which includes Chicago and Milwaukee. Other values include both regions. 

(California oxygen-only surveys were not included in the oxygenate computations.)

The higher sulfur levels in Chicago and Milwaukee RFG areas affected its relative complex model

performance for all three pollutants (VOC, NOx, toxics). This analysis indicates that sulfur was the

primary factor influencing relative VOC and NOx performance, and that sulfur may have some influence

on toxics performance. The margin of air toxics overcompliance was not as great in Chicago and

Milwaukee as in other areas primarily due to higher benzene content, but other factors such as increased

acetaldehyde emissions and sulfur levels also contributed. Oxygenates had little impact on VOC or NOx

performance. 
34 Estimate from 1997 RFG Survey Data. 

26

Table B2. Chicago and Milwaukee Data

National

Average Chicago Milwaukee

MTBE (wt% oxygen) 1.62 0.08 0.06 

ETBE (wt% oxygen) 0 0 0 

Ethanol (wt% oxygen) 0.51 3.38 3.39 

TAME (wt% oxygen) 0.12 0 0 

SULFUR (ppm) 190 255 261 

RVP (psi) region 2 7.9 7.9 7.9 

E200 (%) 49.4 50.7 50.9 

E300 (%) 82.7 81.8 82.2 

AROMATICS (vol%) 26.0 25.1 24.9 

OLEFINS (vol%) 10.3 6.7 7.0 

BENZENE (vol%) 0.68 0.90 0.99 

III. The Impact on RFG if Oxygenates are Removed

A. Introduction

MTBE provides about 76 percent of the oxygenate used in all RFG, and ethanol provides about 19

percent. The remaining 5 percent is made up of other ethers, tertiary-amyl methyl ether (TAME) and

ethyl tertiary butyl ether (ETBE).34 MTBE and ethanol have been the primary oxygenates in RFG

because of their availability, blendability, and ability to deliver air quality benefits while meeting

American Society for Testing and Materials (ASTM) specifications. (Refer to Table D1 in Issue

Summary D, Fuel Supply and Cost, for usage data and references.) 

As shown in Table I above, Phase I RFG currently overcomplies with VOC, NOx, toxics, and benzene

requirements. The key question is whether this current overcompliance with the Phase I RFG standards

will be maintained in Phase II RFG if oxygenates are not required. Because the Phase II performance

standards for VOCs and NOx are above the current actual performance of Phase I RFG, all fuels will be

required to maintain or exceed the current VOC and NOx benefits, whether or not they contain

oxygenates. However, since the Phase II performance standard for air toxics (22 percent reduction) is

below the current Phase I actual reductions (average 33 percent reduction), there is no guarantee that the

current (Phase I) level of air toxics benefits will be maintained in all cases

The impact of removing oxygenates such as MTBE is not likely to be identical for CaRFG and Federal

RFG. Federal RFG is subject to fewer caps on specific properties (e.g. aromatics) than CaRFG and

therefore is more likely to show emissions impacts from the removal of oxygenates. Specific fuel

parameters (e.g. the CaRFG cap on aromatics) may provide extra assurance that certain pollution

reductions occur. Alternatively, performance standards (such as the current mass-based requirements for

toxics and VOCs) assure that pollution reductions will occur, but allow the refiner more flexibility in

determining how to achieve those reductions.
35 Air toxics emissions reductions result primarily from reductions in RFG of aromatics and benzene (itself an

aromatic) when compared to pre-RFG gasoline. 

36 The production of octane quality is the primary performance property considered by refiners in the

production of gasoline. All refining/blending decisions are based, in part, on the need for a certain minimum level

of octane quality in order that vehicles using the fuel operate properly. There are a limited number of octane rich

components that refiners can choose to produce needed octane. Aromatics, alkylates, and oxygenates are three of

the most available sources of octane quality for U.S. refiners. The most important (and for most refiners, the most

economical) gasoline upgrading process in U.S. refineries is catalytic reforming which produces aromatics and

increases the octane quality of the gasoline. (See, for example, Anderson, Robert O., Fundamentals of the

Petroleum Industry, University of Oklahoma Press, 1984, p. 221.) Reforming changes the shape of straight-chain

carbon molecules to high-octane ring-shaped molecules. These ring-shaped molecules are referred to as aromatics

and include benzene and benzene-like molecules. Since oxygenates are also primarily used for octane enhancement

when producing gasoline, for a refiner using these two octane sources, there exists a gasoline balance situation

between the use of aromatics and the use of oxygenates. Although the increased use of alkylates would also be

expected as oxygenates are reduced, U.S. reforming capacity to produce aromatics is far greater than is the capacity

to produce alkylates.

Under the federal RFG program, the oxygenate requirement results in a high level of octane quality and,

for the reasons mentioned above, would be expected to push the use of aromatics and benzene from reforming in a

downward direction. (Addition of oxygenate volumes would result in more than a 10 percent decrease in aromatics

and benzene from dilution alone, even if the octane quality properties are ignored.) Refiners would not be expected

to utilize refinery capacity to produce aromatics that are not needed for octane. Since aromatics (including benzene)

are the strongest contributors to the formation of toxics in the complex model, it is reasonable to conclude that the

use of oxygenates and the resulting downward movement in aromatics and benzene is likely responsible for a

substantial amount of the overcompliance in toxic emission reductions.

27

B. Air Toxics

Current RFG over complies with both the Phase I and planned Phase II toxics standards. With the data

available the panel could not determine with precision all of the factors which produce this

overcompliance. However, as is explained below, when blending gasoline, it is reasonable to conclude

that the use of octane-rich oxygenates is one of the factors that affects a refiner’s decision to use highoctane aromatics, a major contributor to the formation of toxic emissions.35

Decisions about refinery blending are complex and vary greatly over the range of U.S. refineries. 

Despite the variability in fuels likely to result from this complex system, however, certain trends can be

identified that may help explain the larger-than-expected air toxics benefits.

& First, it would be expected that each refiner would incorporate a measurable degree of

overcompliance in order to ensure that their fuel never falls below the standard.

& Second, no matter how refiners blend fuel to meet the air quality standards, fuels will also be

blended to maintain at least the minimum octane required for current automobiles. Thus, one

would expect that with increased use of oxygenates (a high octane component) in RFG, one

would see, on average, reduced need for, and use of, other high-octane components such as

aromatics. Conversely, one would expect that with reduced use of oxygenates, this octane need

would be met, in part, with increased use of aromatics and, in the longer term once capacity is

expanded, alkylates.36

& Third, although it is difficult to determine the precise role that oxygenates play in

overcompliance, and some fuels would likely be blended by some refiners with lower oxygen yet
37 NESCAUM, RFG/MTBE Findings and Recommendations, Boston, MA, August, 1999.

38 University of California, Health and Environmental Assessment of MTBE, Volume I. Summary and

Recommendations, P.16, November 1998.

39 NESCAUM, RFG/MTBE Findings and Recommendations, Boston, MA, August, 1999.

28

high air toxics benefits, on average one would expect the presence of higher levels of oxygenate

in the fuel to lead to reduced levels of aromatics, and thus greater air toxics benefits.

Although reasonable to assume that oxygenates thus contribute to toxics overcompliance, it is difficult to

quantify this effect. The ideal data set would be able to compare fuels blended to meet current RFG

requirements with a full range of oxygen levels (i.e. 0%, .5%, 1.0%, 2%, etc.), and such a data set does

not exist. There is limited data from the State of Maine which recently implemented its own fuel

program, albeit with less stringent requirements than RFG, to substantially reduce the use of MTBE: fuel

properties reported by Maine’s gasoline suppliers and distributors show a decrease in MTBE use by 50%

and a corresponding increase in aromatics of 20% over the levels of aromatics present in RFG sold in

Maine in 199737. There is also data from Northern California (where 2.0% oxygen is not required) that

CaRFG sold in the San Francisco area contained over 8% by volume MTBE in 1997 in part to meet the

more stringent CARB requirements for CaRFG, although such data must be interpreted carefully since

both the RFG requirements and the market situation in California are unique38.

The only other available data set is data on actual RFG fuel properties collected as part of the

implementation of the program. At the Panel’s request, EPA analyzed available data on actual RFG

properties in the marketplace and the relationship in that data between MTBE use, air toxics and

aromatics content. The EPA’s regulations allow producers of RFG to meet the oxygen content

requirement on an averaged basis and to employ oxygen credits to meet the averaged standard of 2.1

percent by weight. Consequently, the oxygen content in any given sample of RFG may vary to a limited

degree from the statutory 2.0 percent by weight per gallon requirement. In 1998 RFG fuel quality

surveys, the oxygen content of samples that did not contain ethanol but were oxygenated wholly or in

part with MTBE, varied between about 1.5 and 3.0 percent by weight. Even though the availability of

this data provides an opportunity to explore how aromatics content changes as oxygen levels vary, most

of the data points clustered around the 2.1 percent average standard and the data set contains no data for

oxygen levels below the regulatory minimum of 1.5 percent. Therefore, although the analyses performed

for the Panel showed a weak positive correlation between oxygen levels and both toxics performance and

aromatics content, and more recent analyses by the Colorado School of Mines of the same data found

some stronger correlations,39 the Panel concluded that this data is extremely limited and can not be used

for the purpose of coming to any specific quantitative statistical conclusions. 

In the absence of certainty on the effects of removing oxygenates, the primary concern is that if the

oxygen mandate is removed and a significant amount of RFG does not contain oxygenates, use of

aromatics might rise at least in some portion of the RFG fuel blends. Such a rise would likely decrease

the overcompliance now seen for toxics in Federal RFG. In California, where CaRFG both requires

much lower sulfur levels and places a limit on the level of aromatics allowed in the fuel, such

overcompliance is more likely to continue. In the absence of certainty around this issue, the only way to

ensure that there is no loss of current air quality benefits is for EPA to seek mechanisms for both the

RFG Phase II and Conventional Gasoline programs to define and maintain in RFG II the real world

performance observed in RFG Phase I while preventing deterioration of the current air quality

performance of conventional gasoline.
40 EPA estimate based on complex and MOBILE model calculations.

41 Colorado Department of Public Health and Environment (Ken Nelson and Ron Ragazzi), The Impact of a 10

percent Ethanol Blended Fuel on the Exhaust Emissions of Tier 0 & Tier 1 Light Duty Gasoline Vehicles at 35 F,

March 26, 1999.

42 This study involved testing light duty vehicles (LDVs) and trucks (LDTs) at 35 (F. Twelve Tier 0 and 12

Tier 1 vehicles (8 LDVs, 4 LDTs), six high emitters, and one low emission vehicle (LEV), were tested under three

driving cycles [Federal Test Procedure (FTP), Unified, and REPO5]. The FTP is based on typical urban driving

patterns. The Unified Cycle has higher speeds and accelerations than the FTP, and the REPO5 is a very aggressive

driving cycle. In this program, the FTP was conducted from a cold start while the other cycles were conducted from

a hot running start. The vehicles were tested with a non-oxygenated fuel and a 10 percent ethanol oxygenated fuel. 

The program measured emissions of hydrocarbons (HC), CO, NOx, carbon dioxide (CO2) and fine particulate

(PM10 and smaller). 

The study reported that FTP particulate emissions were reduced with the oxygenated fuel. For the FTP, a

mean absolute reduction of 3.31 milligrams per mile (mg/mi) or 36.0 percent was achieved for the main group of 24

Tier 0 plus Tier 1 vehicles. The reduction for the Tier 0 vehicles was 5.24 mg/mile, or 39.7 percent, and the

reduction for the Tier 1 vehicles was 1.38 mg/mi, or 26.6 percent. These absolute reductions were statistically

significant at the 95 percent confidence level. The numbers indicate that older vehicles receive greater PM benefits

from the use of oxygenated fuels than newer technology vehicles. No statistically significant differences were

detected for other driving cycles. There were no statistically significant changes in particulate emissions for the high

emitters. Because only one LEV was tested, statistical significance cannot be determined. 

29

There are several possible mechanisms to accomplish this. One obvious way is to enhance the massbased performance requirements currently used in the program. At the same time, the panel recognizes

that the different exhaust components pose differential risks to public health due in large degree to their

variable potency. EPA should explore and implement mechanisms to achieve equivalent or improved

public health results that focus on reducing those compounds that pose the greatest risk. 

C. Carbon Monoxide Benefits

Although there is no carbon monoxide (CO) standard for RFG, oxygenates affect CO emissions so that

current RFG actually produces significant CO benefits. Estimates show that about one-fourth of the CO

benefits associated with oxygenated RFG will disappear if oxygenates are on used.40 Thus, if RFG

contains no oxygenates, the CO reductions associated with RFG will be reduced by approximately 25

percent. This will be less critical in future years due to stricter tailpipe CO emission standards. As the

vehicle fleet turns over, the oxygenate impact on CO emissions diminishes (see Table 3). It is important

to note that there are now relatively few CO nonattainment areas (see discussion of Wintertime Oxyfuel

Program in Section V. below).

D. Particulate Matter Benefits

There are limited data available on the effect of oxygenates on emissions of particulate matter (PM). The

Colorado Department of Public Health and Environment conducted a study to evaluate the effects of

oxygenated fuels on motor vehicle emissions at low ambient temperatures.41 The study, which analyzed

winter oxygenated fuels rather than RFG, concluded that there were statistically significant PM

emissions reductions associated with the use of an ethanol oxygenated fuel.42 Additional research is

necessary including use of ethanol-oxygenated RFG and non-oxygenated RFG fuels in a variety of

climates, to better understand how different formulations of gasoline affect PM.

IV. Other Air Quality Considerations for Oxygenates
43 Reid vapor pressure is a measure of the gas pressure a liquid/gas system will apply to a closed system when

heated to 100 degrees Fahrenheit. As such, RVP is a measure of a liquid’s volatility (i.e., its tendency to evaporate).

44 The size of increase in RVP is clearly affected by other factors, including the hydrocarbon makeup and

original volatility characteristics of the blend into which the ethanol is added.

45 EPA has promulgated a program controlling the RVP of conventional gasoline on a nationwide basis. (See

40 CFR 80.27.) This program allows for a 1.0 psi exemption for 10 percent ethanol blends. Thus, if this program

requires that RVP not exceed 9.0 psi for a given area, 10 percent ethanol blends are allowed at RVPs of up to 10

psi. This exemption for ethanol blends does not apply to the RFG program.

30

A. Ozone Reactivity of Alternatives (CO Reduction)

One key question that has been raised about the air quality effects of RFG has been whether the ozone

reactivity of fuels with different oxygenates could be a better measure of ozone forming potential than

the correct mass-based measurement of VOCs.

A recently released report from the National Research Council (NRC), Ozone-Forming Potential of

Reformulated Gasoline, concluded that there is no compelling scientific basis at this time to recommend

that ozone forming potential or reactivity replace mass of emissions in the RFG program. A change from

the mass of emissions approach to a reactivity approach would not impact the choice of one fuel over

another from the standpoint of air quality benefits. 

The NRC report found that fuel oxygen content appears to have only a small effect on the ozone forming

emissions of RFG with reductions in CO emissions and in exhaust emissions of VOCs but with some

evidence of increases in NOx emissions. The NRC did not examine the contribution of oxygenates to the

emissions of air toxics. 

The NRC report found that the contribution of CO to ozone formation should be recognized in

assessments of the effects of RFG. The NRC committee found that CO emissions account for 15 percent

to 25 percent of the reactivity of exhaust emissions from light duty vehicles and should be included in

reactivity assessments because despite its low reactivity adjustment factor, the large mass of CO

emissions contributes to ozone formation.

B. Ethanol Blend Commingling with MTBE and Hydrocarbon Blends

An RVP43 increase of approximately one pound per square inch (psi) is caused by the addition of ethanol

to a hydrocarbon base fuel.44 As a result, all ethanol blended RFG is now blended with base gasoline that

has had certain high RVP components, such as pentanes and butanes, reduced in order to ensure that

ethanol blended RFG meets RVP requirements.45

Traditional thinking would conclude that when an ethanol blend is commingled with a non-ethanol blend

in a consumers tank, one would see a resulting RVP greater than would be expected from a simple

volume-weighted linear combination of the two blends’ RVPs, at least if a sufficient amount of the

ethanol blend were to be present. Thus, in a 50-50 commingled blend, where 10 percent ethanol gasoline

with an RVP of 8.0 psi is added to an all-hydrocarbon gasoline with the same 8.0 psi RVP, the resulting

blend has an RVP of about 8.5 psi and not 8.0 psi as would be expected when non-ethanol blends are

commingled.
46 The final RVP resulting from the combination of these two hydrocarbon components would actually be

slightly higher than 7.5 psi since the volume of the hydrocarbon portion of the ethanol gasoline is less than the

volume of the hydrocarbon gasoline by an amount equal to the volume of the ethanol component.

47 These are approximations in order to demonstrate basic blending patterns. The volatility of blends resulting

from commingling are not necessarily exact linear interpolations of the volatilities of the commingled blends.

48 Peter Caffrey and Paul Machiele, “In-Use Volatility Impact of Commingling Ethanol and Non-Ethanol

Fuels,” SAE Technical Paper #94065, February 29, 1994. See also, “The Octamix Waiver,” 53 FR 3636, February

8, 1988.

49 Peter Caffrey and Paul Machiele, “In-Use Volatility Impact of Commingling Ethanol and Non-Ethanol

Fuels,” SAE Technical Paper #94065, February 29, 1994.

31

Commingling these two blends is equivalent to first combining the hydrocarbon portion of both blends

and then adding the ethanol from the first blend to the combined hydrocarbon components. The

hydrocarbon gasoline by definition has an RVP of 8.0 psi. The hydrocarbon portion of the ethanol

gasoline had to have an RVP of 7.0 psi (since the subsequent addition of the ethanol produced an ethanol

gasoline with an RVP of 8.0 psi). The hydrocarbon components combine linearly producing a new

hydrocarbon component having an RVP of about 7.5 psi (half way between 7.0 and 8.0 psi).46 Then,

adding in the ethanol component, which would now be about 5 percent of the final blend, increases the

RVP of the final blend to about 8.5 psi. It is important to note that although the new 50-50 commingled

blend would have an ethanol level of around 5 percent, not 10 percent as in the original ethanol blend,

the full 1.0 psi RVP increase due to ethanol addition would still occur even at this lower ethanol level.47

Although this scenario does accurately describe the basic principles involved in volatility changes when

these types of gasolines are blended, the reality is somewhat more complicated. The presence of less

polar oxygenates like MTBE can decrease the volatility bump to some degree when more polar

oxygenates like ethanol (e.g., as an ethanol blend) are added. This mechanism is called cosolvency.48 

One recent study on the impact of ethanol blend commingling concluded in part that an RVP bump of

slightly greater than one psi occurs when ethanol is added at a two volume percent level in an allhydrocarbon blend, but that a bump of 0.7 psi occurs when ethanol is added to an MTBE blend at the

same original RVP level.49

In addition to the expected RVP increase, many other factors are extremely important in determining the

effect of commingling. These include ethanol blend market share, station/brand loyalty, and the

distribution of fuel tank levels before and after a refueling event. Caffrey and Machiele attempted to take

these variables into account in modeling the effect of ethanol blend commingling in a mixed fuel

marketplace. Their conclusions include the following:

(1) Brand loyalty and ethanol market share are much more important variables than the

distribution of fuel tank levels before and after a refueling event.

(2) Commingling effects can cause a significant increase in fuel RVP. 

(3) Commingling effects are clearly more dramatic in a market in which a significant portion of

the gasoline is all-hydrocarbon (i.e., non-oxygenated). Depending on the combination of

variables chosen (i.e., especially ethanol market share), the RVP increase over the entire gasoline

pool can range from around 0.1 to 0.3 psi in a reformulated gasoline market (i.e., ethanol blends

commingled only with MTBE blends). Analogous increases for a non-reformulated market (i.e.,
50 NESCAUM, Relative Cancer Risk of Reformulated Gasoline and Conventional Gasoline Sold in the

Northeast, August 1998. 

51 U.S. Energy Information Administration (Aileen Bohn and Tancred Lidderdale), Demand and Price Outlook

for Phase 2 Reformulated Gasoline, 2000, April 1999. Data indicate that 5 thousand barrels per day oxygenate

demand for conventional gasoline. 

32

ethanol blends commingled only with all-hydrocarbon blends) range from under 0.1 psi to over

0.4 psi.

(4) The effects of the increase in RVP commingling approaches a maximum when the ethanol

market share becomes 30 to 50 percent, and declines thereafter as ethanol takes a larger market

share.

C. Fuel Quality in Conventional Gasoline 

Conventional gasoline is controlled under EPA’s Anti-Dumping Program. When the reformulated

gasoline (RFG) regulations were introduced, an anti-dumping program was also introduced. Refiners

(and importers) were required to provide information on CG to show that its properties become no worse

than they were in 1990. This program was meant to prevent refiners from simply removing “bad”

blendstocks from RFG and dumping these into CG. In order to show that properties of CG would not

deteriorate, refiners established individual 1990 baselines for CG, which were independently audited and

submitted to the EPA. Refiners who could not establish a baseline because of insufficient available

information were required to adopt the Clean Air Act baseline included in the statute. (Most parties

believe that the Clean Air Act baseline is actually more stringent than a typical individual refinery

baseline.)

However, there is no assurance that CG air toxics benefits gained since 1990 will be protected. The

EPA’s 1997 refinery survey data indicates that 1997 CG sold in the Northeast was 12.8 percent less toxic

than 1990 levels. The data also indicate an additional 3.5 percent VOC reduction in the Northeast over

the 1990 levels.50

Under the complex model, refiners must not exceed their 1990 baselines for exhaust toxics and NOx. 

Although EPA does collect information on the quality of CG, the first data on complex model CG (from

1998) were not required to be submitted to EPA until May 31, 1999. The analysis of that data will take

at least several months. Thus, at this time the EPA does not have current data on whether complex model

CG toxics is in overcompliance. The Agency has indicated, however, that this analysis would be a

critical element of guaranteeing that future increase in emissions potential will not occur in CG. Once

the analysis is completed, EPA should review any regulatory or administrative authorities available to

prevent deterioration of the current air quality performance of conventional gasoline. 

If MTBE use was phased out, the antidumping program would prevent any increase in CG from 1990

NOx and toxics levels only. However, should MTBE be eliminated and ethanol use increase in CG,

Department of Energy (DOE) modeling shows a 6 to 7 percent VOC increase in conventional gasoline

due to the one pound waiver for ethanol use outside RFG areas. Regarding MTBE use in CG, the Energy

Information Administration (EIA) data show that very little MTBE is actually used in conventional

gasoline;51 estimates range, however, from 4,000 to 25,000 barrels per day. It should be noted that the

anti-dumping program would not prevent increases in MTBE use in CG. 
52 The Panel is aware of the current proposal for further changes to the sulfur levels of gasoline and recognizes

that implementation of any change resulting from the Panel’s recommendations will, of necessity, need to be

coordinated with implementation of these other changes. However, a majority of the Panel considered the

maintenance of current RFG air quality benefits as separate from any additional benefits that might accrue from the

sulfur changes currently under consideration.

33

EPA is also pursuing other initiatives that are related to the quality of CG. EPA has proposed a gasoline

sulfur program and, if any form of sulfur control program were adopted nationally, NOx levels in CG

would clearly be better than current levels.52 The Agency is also in the process of evaluating mobile

source air toxics and is expected to issue a proposal in early 2000, at which time the Agency will further

address the issue of toxic emissions.

V. Wintertime Oxyfuel Program

A. Introduction

In addition to the RFG program, the CAAA of 1990 required the establishment of a Wintertime Oxyfuel

program. Under this program gasoline must contain 2.7 percent oxygen by weight during the wintertime

in areas that are not in attainment for the National Ambient Air Quality Standards for CO. 

In 1992, when the oxygenated fuels program began, there were 36 areas implementing the program. The

1998-99 oxygenated fuels season had 17 areas implementing the program. Nineteen areas were able to

redesignate to CO attainment due to the implementation of the oxygenated fuels program along with

other control measures. Of the remaining 17 areas, eight have data to redesignate and are either working

on or have submitted redesignation requests to EPA, or they have chosen to continue to implement the

program as a CO control measure even though they have attained the standard. Six areas are classified as

"serious" CO nonattainment areas, and the remaining three areas are classified as "moderate" CO

nonattainment areas; all of these areas continue to implement the program in an effort to attain the CO

standard. 

Most of the winter oxygenated fuel areas use ethanol. The only two areas using MTBE for the winter

oxygenate program are Los Angeles and the New York City metropolitan area. It is a possibility that

New York City, which includes metropolitan Connecticut, New Jersey, and New York, will leave the

program before the next winter season because they will demonstrate attainment with the CO standard. 

Los Angeles will need to phase-out MTBE use under the Governor's recent directive. Therefore, MTBE

use for winter oxygenated areas is not likely to be common in the future.
53 Office of Science and Technology Policy, National Science and Technology Council , Interagency

Assessment of Oxygenated Fuels, June 1997.

54 Office of Science and Technology Policy, National Science and Technology Council, Interagency

Assessment of Oxygenated Fuels, June 1997, p. iv.

55 U.S. Environmental Protection Agency, Office of Mobile Sources, (R. Cook), Impact of the Oxyfuel

Program on Ambient CO Levels, 1996.

56 Systems Application International, Regression Modeling of Oxyfuel Effects On Ambient CO Concentrations,

January 1997.

57 Office of Science and Technology Policy, National Science and Technology Council, Interagency

Assessment of Oxygenated Fuels, June 1997, p. iv.

34

B. Air Quality Benefits

The most comprehensive study regarding oxygenated fuels was completed in June 1997 by the Office of

Science and Technology Policy (OSTP).53 The report concluded that "analyses of ambient CO

measurements in some cities with winter oxygenated fuels programs find a reduction in ambient CO

concentrations of about 10 percent."54 The report also suggested "the need for a thorough, statistically

defensible analysis of ambient CO data." In response to that suggestion, EPA initiated a study55 that

analyzed ambient CO data from about 300 monitoring sites. The study indicated a downward shift in

ambient CO ranging from 6 percent to 13 percent for the six month winter season in areas implementing

an oxyfuel program in 1992. This EPA study was further refined by Systems Applications International

(SAI).56 The SAI study analyzed summer (June and July) and winter (December and January) bimonthly

means or maximum daily 8-hour CO concentrations from 1986 to 1995. The report concluded that there

was a substantial (14 percent reduction) and statistically significant association (± 4 percent with 95

percent confidence) between the use of oxyfuels and monitored CO concentrations.

On this point, the OSTP report concluded: 

Older technology vehicles (carbureted and oxidation catalysts) benefit more from the use

of oxygenated fuel. The amount of pollutant emissions is smaller in newer technology

vehicles (fuel injected and adaptive learning, closed loop three-way catalyst systems). 

Additionally, the percentage reductions in CO and hydrocarbon emissions from the use

of fuel oxygenates are found to be smaller in the newer technology vehicles compared to

older technology and higher emitting vehicles.57 

Analysis by the EPA (MOBIL6 Model) also indicates that even with fleet turnover, a significant

contribution to CO reduction from the winter oxygenated program is expected until at least 2005

(Table 3).
58 MOBILE6 effects are draft only. Only after MOBILE6 is finalized will actual and more accurate estimates

be available. These projected MOBILE6 Oxy-on-CO effects are based on MOBIL Report #M6.FUL.002, which is

posted on the MOBILE6 web site (http://www.epa.gov/OMS/M6.htm.) 

35

Table 3. Percent Reduction in CO Emissions Resulting from 3.5 Percent Oxygen, 

As Predicted by the MOBILE Model58

Year MOBILE6

1997 10% to 20%

2000 5% to 15%

2005 0% to 10%

2010 0% to 2%

Source: U.S. Environmental Protection Agency

Most winter oxygenated areas use ethanol, which is typically blended at 3.5 percent by weight. 

Therefore the chart reflects actual benefits rather than the benefits that may result from the regulatory

requirement of 2.7 percent oxygen by weight. If a lower oxygen level is used, one would expect there to

be a linear downward trend in benefits.

The U.S. Environmental Protection Agency’s Area by Area analysis of 1998 RFG Survey Data indicates

that the complex model emissions performance of RFG in Chicago and Milwaukee, while easily

exceeding all Phase I performance (i.e., emission reduction) requirements, generally ranks low compared

to other RFG areas. In order to investigate factors influencing the performance of Chicago and

Milwaukee RFG relative to RFG in other areas, it is necessary to consider the composition of the fuels.

The Chicago and Milwaukee property values were similar, and there were notable differences from the

National Average properties. The sulfur and benzene levels for Chicago and Milwaukee were

substantially higher. These two areas had the highest and second highest levels of all areas for these

parameters. Oxygenate type and oxygen content differed from the National Average. Ethanol was the

primary oxygenate used in these areas. Therefore, the total oxygen content and the ethanol contribution

to total oxygen were highest for these areas. Olefin content was lower than the National Average RFG,

and the olefin content for these two areas was the lowest of all areas surveyed.

The higher sulfur levels in the Chicago and Milwaukee RFG affected its relative complex model

performance for all three pollutants. This analysis indicates that sulfur was the primary factor

influencing relative VOC and NOx performance, and that it may have some influence on toxics

performance. Although 1998 RFG Survey Data indicates that the complex model emissions performance

of RFG in Chicago and Milwaukee, easily exceeded all Phase I performance (i.e., emission reduction)

requirements. The margin of air toxics overcompliance was not as great there as in other areas primarily

due to higher benzene content, but other factors such as increased acetaldehyde emissions and sulfur

levels also contributed. Oxygenates had little impact on VOC or NOx performance. 
36

It is important to realize that this analysis was intended to identify factors which caused Chicago and

Milwaukee to rank lower than most other RFG areas in complex model emissions performance. The

approach was to vary one property at a time and look at its effect on emissions performance. In reality,

fuel properties are not independent, and this “one at a time” analysis was not intended to answer more

complex questions such as “What would happen to fuel properties and emissions performance if Chicago

and Milwaukee RFG suppliers switched from ethanol to MTBE?”
0 5 10 15 20 25 30 35 

Per. Gal. Std.

Averaged Std.

Washington, D.C.

Baltimore, MD

Dallas,TX

Richmond,VA

Norfolk,VA

Houston,TX

Per. Gal. Std.

Averaged Std.

NY-NJ-LI-CT

Milwaukee, WI

Chicago, IL

Philadelphia, PA

Poughkeepsie, NY

Hartford, CT

Boston, MA

CT (remainder)

Manchester, NH

Springfield, MA

Portsmouth-Dover, NH

Covington, KY

Rhode Island

Portland, ME

Louisville, KY

Lewiston-Auburn, ME

Percent Reduction from 1990 Baseline

VOC Reg. 2

Figure B1. RFG Survey Data, Summer 1998: Phase I VOC Reduction

Appendix B
0 5 10 15 20 25 30 

Per. Gal. Std.

Averaged Std.

Milwaukee, WI

Chicago, IL

Louisville, KY

Covington, KY

Houston,TX

Portland, ME

Lewiston-Auburn, ME

Portsmouth-Dover, NH

Norfolk,VA

Dallas,TX

Manchester, NH

Richmond,VA

Philadelphia, PA

NY-NJ-LI-CT

Washington, D.C.

Poughkeepsie, NY

Baltimore, MD

Hartford, CT

CT (remainder)

Boston, MA

Springfield, MA

Rhode Island

Percent Reduction from 1990 Baseline

Figure B2. RFG Survey Data, Summer 1998: Phase I Toxics Reduction
0123456

Per. Gal. Std.

Averaged Std.

Milwaukee, WI

Louisville, KY

Richmond,VA

Chicago, IL

NY-NJ-LI-CT

Washington, D.C.

Poughkeepsie, NY

Norfolk,VA

Covington, KY

Baltimore, MD

Houston-Galveston, TX

Hartford, CT

CT (remainder)

Dallas-Fort Worth, TX

Manchester, NH

Philadelphia, PA

Lewiston-Auburn, ME

Portland, ME

Springfield, MA

Rhode Island

Portsmouth-Dover, NH

Boston, MA

Percent Reduction from 1990 Baseline

Figure B3. RFG Survey Data, Summer 1998: Phase I NOx Reduction
59 State of Maine Bureau of Health, Department of Human Services, Bureau of Waste Management &

Remediation, Department of Environmental Protection, Maine Geological Survey, and Department of Conservation,

Maine MTBE Drinking Water Study, The Presence of MTBE and other Gasoline Compounds in Maine's Drinking

Water--Preliminary Report, 1998.

40

C. Prevention, Treatment, and Remediation

I. Introduction

This Issue Summary reviews the technical and regulatory approaches to reducing the sources of

oxygenate impacts on water resources; release prevention and detection; storage tank-related issues;

Federal and State approaches to protecting drinking water sources; the treatment of impacted drinking

water; the remediation of oxygenate-impacted ground water; and funding sources. Because of recent

detections of methyl tertiary butyl ether (MTBE) in drinking water supplies, MTBE is emphasized

throughout this section. The body of information available to evaluate impacts of other gasoline

oxygenates on water resources is significantly more limited.

The water resources described in this section are generally divided into two categories: surface water

(streams, lakes, reservoirs, and stormwater); and ground water (water table and confined aquifers). 

Drinking water refers to those water resources currently used for public and private water supply

systems. Although a variety of sources of MTBE impacts to water quality have been identified, this

section focuses primarily on releases from underground storage tank (UST) systems, as this population

comprises the vast majority of the known potential point sources and has been studied in much greater

detail than other potential sources of MTBE impact.

II. Sources and Trends of Water Quality Impacts

As described in Issue Summary A (Water Contamination), surface water and ground water resources are

impacted by both gasoline oxygenates and a variety of other natural and anthropomorphic sources of

contaminants. There are a number of primary sources that appear to be responsible for most identified

MTBE impacts: 

• Underground storage tanks, other gasoline storage and distribution facilities,

such as bulk storage terminals, small household/farm gasoline tanks, and

aboveground storage tanks;

• Interstate and intrastate petroleum pipelines;

• Small releases (e.g., gasoline tank ruptures during car accidents or consumer

disposal of gasoline in backyards) appear to have been the source of private well

contamination in Maine.59 These types of releases are also expected to be a

source of contamination to private wells in other States;

• Engine exhaust and related releases (e.g., spillage) into lakes and reservoirs from

two-stroke watercraft and older four-stroke watercraft;

• Stormwater runoff.
60 U.S. Environmental Protection Agency, Office of Underground Storage Tanks, “Corrective Action

Measures Archive,” http://www.epa.gov/swerust1/cat/camarchv.htm.

61 U.S. Environmental Protection Agency, Office of Water, National Water Quality Inventory: 1996 Report to

Congress, 1996. 

41

A. Assessing Impacts and Trends

There are no comprehensive quality assessments of our nation’s water resources that can provide clear

indications of the trend of MTBE impacts on water supplies. Further, it is unknown how frequently

gasoline compounds are released from the current population of UST systems or the quantity of gasoline

that is released. As such, it is unknown whether releases of gasoline and related impacts to water

resources are continuing to grow, whether increasing awareness of this issue has stabilized or reduced the

frequency of such releases, or whether they are on the decline. Not all States require monitoring for

MTBE at LUFT sites and in drinking water quality sampling, further preventing a full characterization of

MTBE’s current or potential future impacts. 

New Federal and State UST regulations promulgated in the 1980's have spurred comprehensive

assessments and corrective action programs at facilities with USTs. As of December 1998, many

currently regulated UST facilities can be expected to have had some type of site assessment conducted as

part of compliance activities and property transfer information requirements in order to determine

whether there have been any releases. The number of identified UST releases has grown steadily during

the last decade, averaging about 20,000 new known releases annually.60 Most releases have been

discovered with tank removal during the tank upgrading process, rather than being detected as part of a

continuous monitoring program. Thus, it is not possible to know when the release actually occurred

(e.g., many releases reported in 1998 occurred in previous years, but were only discovered in 1998). The

rate at which new release sites are discovered is expected to decrease in coming years, as most UST

facilities being evaluated for contamination were in the process of meeting the December 1998 upgrading

deadline. Because of limitations inherent in current leak detection technologies, it is expected that

releases reported in future years from the current population of upgraded facilities will not provide a

more accurate characterization of the occurrence of new releases. 

Limited information is available regarding releases from other gasoline storage/distribution facilities, and

very little data exist to characterize the extent to which other types of gasoline releases occur.

B. Underground and Aboveground Storage Tanks

Underground storage tanks represent the largest population of potential point sources of gasoline releases

to ground water.61 Gasoline storage and distribution facilities are of particular importance as potential

sources of ground water contamination from MTBE and other oxygenates, because these facilities can

release relatively large volumes of gasoline (e.g., hundreds of gallons to thousands of gallons), which

can result in localized subsurface impacts with aqueous concentrations in excess of 100,000 parts per

billion (ppb) adjacent to the release source, as well as extensive dissolved plumes at lower

concentrations. In California, MTBE (associated with gasoline releases throughout the State) is a

frequent and widespread contaminant in shallow groundwater. Detections of MTBE are reported at 75

percent of sites where fuel hydrocarbons have impacted ground water. The minimum number of MTBE

point sources from leaking underground storage tank (LUST) sites in California is estimated at greater

than 10,000. Maximum concentrations at these sites ranged from several ppb to concentrations greater

than 100,000 ppb, indicating a wide range in the magnitude of MTBE impacts at these sites (Table 1).
62 U.S. Environmental Protection Agency, Office of Underground Storage Tanks, based upon FY 1999 SemiAnnual Activity Report – First Half (unpublished).

63 National Petroleum News, Market Facts 1998 (Arlington Heights, IL: Adams Business Media, 1998), p.

124. 

64 There is no database that identifies the specific locations of these federally regulated facilities or their

proximity to drinking water supply sources. See U.S. Environmental Protection Agency, Office of Underground

Storage Tanks, “Corrective Action Measures Archive,” http://www.epa.gov/swerust1/cat/camarchv.htm.

65 U.S. Environmental Protection Agency, Underground Heating Oil And Motor Fuel Tanks Exempt From

Regulation Under Subtitle I Of The Resource Conservation And Recovery Act (May 1990).

42

Table 1. Comparison of Maximum MTBE Ground Water Concentrations Collected by the California

Regional Boards, January 1999

MTBE Concentration

(Parts Per Billion)

Sites Exhibiting Concentration

Level (Percent)

<5 23%

5-50 12%

50-200 11%

200-1,000 17%

1,000-5,000 14%

5,000-20,000 13%

20,000-100,000 7%

>100,000 3%

Note: Data represent collections from 4,300 sites.

Source: Happel, Dooher, and Beckenbach, “Methyl Tertiary Butyl

Ether Impacts to California Groundwater,” presentation at the March

1999 MTBE Blue Ribbon Panel meeting.

There are currently an estimated 825,000 regulated USTs at approximately 400,000 facilities.62 Of the

nation’s approximately 182,000 retail gasoline outlets, the “major” oil companies own about 20 percent,

or about 36,000 facilities.63 On average, each of the nation’s retail outlets have about 3 storage tanks,

thus containing a total of approximately 550,000 USTs, 66 percent of the national total. The remainder

of the regulated UST population consists of state or federally owned facilities and nonretail fueling

facilities (e.g., on-site fueling for taxis, rental cars, delivery trucks, etc.). Over the past 10 years,

approximately 1.3 million Federally regulated USTs have been closed, i.e., removed or properly emptied,

cleaned, and buried in place.64

There are approximately 3 million underground fuel storage tanks exempt from Federal regulations (e.g.,

certain farm and residential gasoline tanks and home heating oil tanks).65 Large aboveground storage

tanks (ASTs) at refineries and distribution terminals, however, are regulated under both State and Federal

laws, including the Spill Control and Countermeasures (SPCC) regulations of the Oil Pollution Act

(OPA) of 1990. There are currently over 10,000 facilities with this type of bulk storage of gasoline. As

compared with USTs, there is no comparable Federal regulatory program for ASTs, and thus current

release statistics for ASTs are not available. A 1994 American Petroleum Institute (API) survey
66 American Petroleum Institute, A Survey of API Members’ Aboveground Storage Tank Facilities, July 1994.

67 The U.S. Department of Transportation (DOT)’s Office of Pipeline Safety (OPS) oversees the safety and

environmental regulation of interstate petroleum pipelines. Petroleum pipelines are also subject to economic

regulation by the Federal Energy Regulatory Commission (FERC). 

68 Development of the definition and its subsequent application are subject to notice and comment

requirements under Federal rulemaking procedures. 

43

estimated that ground water contamination had been identified at approximately 68 percent of marketing

terminals with ASTs, 85 percent of refinery tank fields with ASTs, and 10 percent of transportation

facilities with ASTs. Of these facilities, over 95 percent were engaged in corrective action under the

guidance of a State or Federal authority.66

C. Pipelines

Excluding intrastate pipelines and small gathering lines associated with crude oil production fields, there

are approximately 160,000 miles of liquids pipelines in the United States.67 These pipelines transport

approximately 12.5 billion barrels of crude oil and refined products annually. Over a recent six-year

period (1993 to 1998), an average of 197 spills occurred annually, with an average volume from all spills

totaling 140,000 barrels per year. Of the volume spilled during this period, crude oil accounted for 44

percent, whereas refined petroleum products (e.g., gasoline, home heating oil, jet fuel) accounted for 31

percent. Although the specific volume of gasoline spilled cannot be readily identified, gasoline

represents the largest volume of refined products transported. Additionally, there are little or no data on

the extent of MTBE releases from pipelines.

In California, pipeline release data are currently being compiled by the Office of the State Fire Marshal,

which regulates approximately 8,500 miles of pipelines. Since 1981, there have been approximately 300

pipeline releases within the State Fire Marshal’s Jurisdiction. 

The pipeline industry is working with pipeline regulators and environmental trustee agencies to develop a

definition of areas that may be unusually sensitive to environmental damage from pipeline leaks to be

used in conducting future risk assessments along pipeline rights-of-way. Included under the draft

definition are areas with drinking water resources, which are based on EPA’s standards for defining both

surface and subsurface drinking water supplies. Once work is completed both on drinking water and

biological resources that may be unusually sensitive to environmental damage, OPS will make

information available for pipeline operators to use in conducting risk assessments along pipeline rightsof-way. The Office of Pipeline Safety may also require increased pipeline integrity standards to prevent

releases in unusually sensitive areas.68 

In California, the locations of fuel pipelines and drinking water wells are being integrated into a

geographic information system (GIS), which is discussed in greater detail in Section V of this Issue

Summary. The State Fire Marshal Office is required at least once every two years to determine the

identity of each pipeline or pipeline segment that transports petroleum products within 1,000 feet of a

public drinking water well. Furthermore, these pipelines’ operators must be notified to prepare a pipeline

wellhead protection plan for the State Fire Marshal's approval.

D. Small Releases
69 State of Maine Bureau of Health, Department of Human Services, Bureau of Waste Management &

Remediation, Department of Environmental Protection, Maine Geological Survey, and Department of Conservation, 

Maine MTBE Drinking Water Study, The Presence of MTBE and Other Gasoline Compounds in Maine's Drinking

Water--Preliminary Report, 1998.

70 G.A. Robbins et al., “Evidence for MTBE in Heating Oil,” Ground Water and Remediation, Spring 1999,

pp. 65-68.

71 M.S. Dale et al., “MTBE -- Occurrence and Fate in Source-Water Supplies,” in American Chemical Society

Division of Environmental Chemistry preprints of papers, 213th, San Francisco, CA: American Chemical Society,

v. 37, no. 1, 1997, pp. 376-377; J.E. Reuter et al., “Concentrations, Sources, and Fate of the Gasoline Oxygenate

Methyl Tert-Butyl Ether (MTBE) in a Multiple-Use Lake,” Environmental Science & Technology, 1998, v. 32, mo.

23, pp. 3666-3672.

72 J.E. Reuter et al., “Concentrations, Sources, and Fate of the Gasoline Oxygenate Methyl Tert-Butyl Ether

(MTBE) in a Multiple-Use Lake,” Environmental Science & Technology, 1998, v. 32, mo. 23, pp. 3666-3672.

44

Small releases from automobile accidents, consumer disposal of “old” gasoline, or other backyard spills

during fueling operations have been identified by officials in Maine as sources of contamination of

private drinking water wells. For example, in a 1998 study of over 900 private household drinking water

wells in Maine, approximately 16 percent had detectable MTBE concentrations, and about 1 percent

contained concentrations exceeding the State of Maine's 35 ppb drinking water standard.69 In one

incident in Maine, about 7 to 12 gallons of gasoline spilled during a car accident contaminating 24

nearby private wells installed in a bedrock aquifer. Eleven of the wells had MTBE concentrations in

excess of 35 ppb. Following the excavation of the contaminated soil, well monitoring at this site has

indicated that MTBE levels are decreasing rapidly in all wells. Similarly, home heating oil storage tanks

have also been identified as potential sources of MTBE contamination, as MTBE might be present from

mixing the heating oil with small volumes of gasoline in the bulk fuel distribution or tank truck delivery

systems.70

E. Watercraft

Gasoline-powered watercraft have contributed to the contamination of lakes and reservoirs with MTBE. 

These impacts are primarily attributed to exhaust discharges from two-stroke engines, which are the most

commonly used engine type in such watercraft. The two-stroke engines discharge in their exhaust up to

30 percent of each gallon of gasoline as unburned hydrocarbons. In two recent studies examining MTBE

contamination at lakes at which reformulated gasoline (RFG) with MTBE was used, concentrations of

MTBE in substantial portions of the lakes’ volume ranged from 10 ppb to 30 ppb after peak periods of

recreational watercraft usage.71 After the boating season ended, these concentrations decreased fairly

rapidly (half-life of approximately 14 days) to low background levels (approximately 1 ppb to 2 ppb or

less). Volatilization is considered the dominant mechanism for this removal process.72

F. Stormwater Runoff

Stormwater runoff is considered a nonpoint source of MTBE contamination. Runoff becomes

contaminated with MTBE from both the dissolution of residual MTBE from parking lots (e.g., service
73 G.C. Delzer et al., Occurrence of the Gasoline Oxygenate MTBE and BTEX Compounds in Urban

Stormwater in the United States, 1991-95, U.S. Geological Survey Water Resources Investigation Report WRIR

96-4145,1996.

74 A.L. Baehr, P.E. Stackelberg, and R.J. Baker, “Evaluation of the Atmosphere as a Source of Volatile

Organic Compounds in Shallow Ground Water,” Water Resources Research, Jan. 1999, v. 35, no. 1, pp. 127-136; 

T.J. Lopes and D.A. Bender, “Nonpoint Sources of Volatile Organic Compounds in Urban Areas -- Relative

Importance of Urban Land Surfaces and Air,” Environmental Pollution, 1998, v. 101, pp. 221-230.

75 Santa Clara Valley Water District Groundwater Vulnerability Pilot Study, “Investigation of MTBE

Occurrence Associated with Operating UST Systems,” July 22, 1999. http://www.scvwd.dst.ca.us/wtrqual/

factmtbe.htm.

45

stations and retail businesses) and roadways and from “atmospheric washout.”73 MTBE contamination

from atmospheric washout is thought to be small compared to that from paved surfaces.74 The United

States Geological Survey (USGS) has characterized MTBE concentrations in runoff in many areas and

has typically found such contamination to be lower than 2 ppb. Stormwater is discharged both to surface

water and to ground water, and thus serves as a source of very low-level MTBE contamination of these

potential drinking water sources.

III. Release Prevention and Detection

A. Prevention 

Since the passage of Federal UST legislation in 1984, improved release prevention practices (e.g.,

corrosion protection, and compatibility between the tank’s construction materials and its contents) has

been required for all new USTs. Following a 10-year phase-in period from the promulgation of EPA

regulations in 1988, as of December 1998, all regulated USTs are required to be protected from

corrosion, small spills, and overfills, and must also have release detection equipment and procedures in

place. Many States have additional and more stringent standards. These regulations are intended to

prevent releases, and should a release occur, to detect it promptly in order to minimize ground water

impacts. Presently, it is not possible to demonstrate the effectiveness of individual States’ UST upgrade

programs or the Federal upgrade program in preventing releases of gasoline from dispensing/storage

facilities. 

Even after tank systems (tanks and piping) are in full compliance with the 1998 regulations, however,

some releases are expected to occur as a result of improper installation or upgrading, improper operation

and maintenance, and accidents. Many of these releases may not be detected as intended due to the

inherent limitations of release detection technologies. 

Anecdotal reports from California, Maine, and Delaware indicate that upgraded USTs continue to have

releases. Efforts are underway by the EPA and in California to evaluate new and upgraded UST systems

to determine which factors may contribute to such releases. In California, for example, the Santa Clara

Valley Water District has completed a study evaluating release prevention and detection performance at

approximately 30 upgraded facilities.75 The California Environmental Protection Agency (CalEPA) is

planning to begin a similar study in 1999. Further studies will likely be required in order to investigate a

representative sampling of the UST population. 
76 U.S. Environmental Protection Agency, Office of Underground Storage Tanks, estimate based upon data

submitted by States on February 28, 1999 and April 30, 1999 (unpublished).

77 Ellen Frye, “When Push Comes to Shove,” LUSTLine, September 1998.

78 Juan Sexton, Kansas State Department of Health & Environment, paper presented at the 10th Annual

UST/LUST National Conference (Long Beach, CA, March 30, 1999); Wayne Geyer, “Above the Ground but not

the Law: ASTs on the Rise, Regulators in Hot Pursuit,” Petroleum Equipment and Technology, July 1999.

79 For example, under one option, a 0.2 gallon per hour release could go undetected in up to 5 percent of all

cases (i.e., it is detected in 95 of 100 instances) and unreported by compliant systems (in a worst case scenario). 

The same technology should not have greater than a 5 percent occurrence of false alarms. Other types of leak

detection may have lower or higher thresholds and still meet the EPA guidelines. A 0.2 gallon/hour release would

result in a release of 1,752 gallons if undetected for one year, and could go undetected for several years.

46

Based on reports received to date from the States, EPA estimates that approximately 80 percent of the

regulated universe of UST systems currently meet the December 1998 requirements.76 By the end of

2000, EPA expects at least 90 percent of the regulated tanks will be in compliance, leaving

approximately 80,000 tanks that have not been upgraded. States’ UST programs are primarily

responsible for implementing and enforcing UST regulations. In augmenting and assisting States’

activities, EPA provides outreach, helps States train UST inspectors, and fosters the exchange of

information among States regarding effective means of securing compliance. Upon a State’s request, or

acting independently when necessary, EPA will also take direct action to enforce the regulations. 

Approximately 20 States now prohibit deliveries to UST systems that are not fully compliant with the

December 1998 regulations, and several major gasoline suppliers have stopped fuel delivery to

non-compliant tanks. These actions, along with the traditional enforcement actions taken by EPA and

States, have contributed to higher compliance rates.77 

The U.S. Environmental Protection Agency and the States also require that USTs that do not meet the

technical standards are properly closed with thorough site assessments for potential releases. Through

December 29, 1999, non-compliant USTs can be temporarily closed, but must be permanently closed,

and any releases identified and remediated, thereafter if not brought into compliance. 

Currently, there is an apparent trend toward using small ASTs (i.e., fewer than 20,000 gallons) to replace

regulated USTs.78 These ASTs are generally not subject to the same release prevention and detection

requirements as USTs. Releases from ASTs may also result in MTBE contamination, and so it may be

necessary to evaluate the performance of such systems. 

B. Detection

Existing regulations require the use of release detection techniques that meet specific performance

criteria. Internal (e.g., automatic tank gauges) or external (e.g., ground water monitoring) approaches

may be used in meeting these criteria. Although these regulations do not allow any detected releases to

go unreported, the regulations do permit several options of varying degrees of sensitivity in the detection

of a release, which can result in smaller releases going undetected for an extended period of time.79 The

regulations, promulgated in 1988, were considered adequate and “best available technology” for typical

gasoline (and other fuels) formulations at the time because hydrocarbon plumes are generally selflimiting (primarily due to intrinsic bioremediation) and thus small releases or slow chronic releases that
80 The use of oxygenates in gasoline was well established by the mid-1980's.

81 Thomas M. Young and the U.S. Environmental Protection Agency, Field Evaluation of Leak Detection

Performance, National Leak Detection Performance Study, 1999.

82 Kevin Couch and Thomas M. Young, “Leaking Underground Storage Tanks (USTs) as Point Sources of

MTBE to Groundwater and Related MTBE-UST Compatibility Issues,” in University of California and UC Toxic

Substances Research & Teaching Program, Health and Environmental Assessment of MTBE, Volume IV, 1998. 

47

remain undetected have typically not resulted in drinking water impacts. The regulations did not address

the use of oxygenates although they were used as octane enhancers at this time, albeit at generally lower

levels than in RFG and oxyfuel.80

Changing existing UST release detection regulations to address the use of oxygenates in gasoline will

require EPA to analyze the risks, costs, and benefits of any regulatory changes. In the past, changing

such a regulation has taken three to five years. The U.S. Environmental Protection Agency has initiated a

field verification study of UST release detection performance and expects initial results in early 2000.81

IV. Underground Storage Tanks

A. Materials Compatibility

The use of oxygenates in gasoline in the conventional gasoline supply was well established in the mid1980's when EPA began formulating the current Federal UST regulations (1998), which formally

identified and addressed compatibility issues. The regulations noted that standard specifications for steel

and fiberglass tank system materials had been established to provide for compatibility with

gasoline/oxygenate mixtures containing up to 15 percent by volume MTBE, 10 percent by volume

ethanol, and 5 percent by volume methanol. Industry standards for materials compatibility have been in

place since 1986. 

A recent evaluation concluded that there are no known studies indicating that any significant

deterioration will occur in metal or fiberglass UST systems as a result of concentrations of MTBE or

other oxygenates in gasoline.82 The same study indicated, however, that given the lack of existing “real

world” characterizations of the long-term performance of typical UST system materials, further

independent quantitative evaluation may be warranted, particularly with regard to potential metallic

corrosion, fiberglass permeability, and the elastomer integrity of gaskets and seals. Because tank and

piping materials may be in contact both with gasoline vapors and water containing high concentrations of

dissolved gasoline components, compatibility with the vapor or aqueous phase of oxygenated gasolines

may also merit study, especially if there is potential for the substantial enrichment of oxygenates in either

phase. 

B. Training, Education, and Certification

It has long been recognized that UST releases can be caused by the failure to adequately perform certain

standard installation and daily operational and maintenance practices. Despite existing regulations that

address many of these practices, owners, contractors, and employees may not routinely exercise

appropriate care in performing these activities. The most frequently identified problem areas include
83 California State Water Resources Control Board, “Are Leak Detection Methods Effective In Finding Leaks

In Underground Storage Tank Systems? (Leaking Site Survey Report)” January 1998.

Http://www.swrcb.ca.gov/~cwphome/ust/leak_reports/Index.htm.

84 U.S. Environmental Protection Agency, Office of Water, State Source Water Assessment and Protection

Programs Guidance, EPA 816-F-97-004, August 1997, www.epa.gov/OGWDW/swp/fs-swpg.html.

48

installation, fuel delivery and procedures, and routine maintenance of dispensers and release detection

equipment.83

Federal UST law contains neither any requirement nor any authority for the certification of owners,

operators, inspectors, or contractors. In practice, most Federal, State, and local inspectors are well

trained, and many UST owners require training for their employees. There is often considerable turnover

of facility employees in State and local programs, however, and constant training is required. A few

States have third party inspection programs requiring that facility owners hire a certified inspector to

document a facility’s state of compliance, although there is anecdotal evidence that these programs are

not followed.

States have taken the impetus in certification and similar programs. For example, half of the States have

programs for licensing or certifying contractors who install, repair, and remove USTs. A smaller

percentage of States (perhaps 25 percent) require certification or licensing of tank testers -- primarily for

those who perform release detection tests. Finally, even a smaller percentage of States, probably around

20 percent, have registration or certification programs for remediation contractors. As these estimates

indicate, further progress could be made in establishing such programs in additional States. 

V. Protection of Drinking Water Sources and Water Quality Management 

A. Federal Efforts

Section 1453 of the 1996 Safe Drinking Water Act (SDWA), as amended in 1996, requires all States to

complete assessments of their public drinking water supplies. By 2003, each State and participating

Tribe must delineate the boundaries of areas in the State (or on Tribal lands) that supply water for each

public drinking water system; identify significant potential sources of contamination; and determine each

system’s susceptibility to sources of contamination. The assessments will synthesize existing

information about the sources of drinking water supplies in order to provide a national baseline of the

potential contaminant threats and to guide future watershed restoration and protection. 

The assessment of drinking water sources is only one part of protecting underground drinking water

sources.84 The Wellhead Protection Program, which was established under the 1986 SDWA

amendments, goes beyond assessment to add additional requirements for prevention within wellhead

protection areas, and to establish contingency plans in the case of a release. Wellhead protection

programs are currently in place in 49 States and territories. Over 125,000 public drinking water systems

have community-level wellhead protection measures in place or under development.

To further identify those areas that may be impacted by MTBE and other contaminants associated with

gasoline, EPA is reviewing all State assessment program submittals to ensure that each program

inventories gasoline service stations, marinas, USTs, and gasoline pipelines in drinking water source
85 The GeoTracker report was a pilot study that addressed the Santa Clara Valley and Santa Monica water

districts - not the entire state. However, the GeoTracker approach is expected to be used to get information for the

rest of the state compiled. For more information about this GIS, refer to http://geotracker.llnl.gov/.

49

protection areas. This will provide an opportunity to collect locational data for water sources and

contaminant sites as part of the State Source Water Assessment Programs. Here, the challenge will be

threefold: (1) to collect information useful to multiple stakeholders; (2) to maintain, update, and improve

the data over time; and (3) most importantly, to make this information easily accessible among agencies 

The U.S. Environmental Protection Agency is also revising its current Unregulated Contaminant

Monitoring Rule. The revised rule, scheduled to take effect in January 2001, will require large water

systems (serving more than 10,000 persons) and a representative sampling of small and medium-sized

water systems (serving fewer than 10,000 persons) to monitor and report MTBE detections, a procedure

that should not add substantially to monitoring costs due to the inclusion of MTBE analysis within

analytical tests used for monitoring of other VOCs. Although this will substantially increase the

monitoring for MTBE, under this regulation, the majority of public groundwater supply wells will still

not be monitored for MTBE. For example, if this regulation were to be enacted today, in California,

MTBE monitoring and reporting would be required for all 3,094 active wells (within water systems

serving more than 10,000 persons) and a representative sample of the other 7,160 active wells (within

water systems serving fewer than 10,000 persons), resulting in fewer than half of the total number of

active wells being monitored.

B. State Efforts

Under California legislation enacted in 1997, the State Water Resources Control Board (SWRCB) is

required to implement a statewide GIS to manage the risk of MTBE contamination to public ground

water supplies. In the short-term (by July 1999), this project seeks (1) to identify all underground storage

tanks and all known releases of motor vehicle fuel from underground storage tanks that are within 1,000

feet of a drinking water well; and (2) to identify public wells within 1,000 feet of a petroleum product

pipeline.85 

This GIS displays and reports detailed information for both tank release sites and drinking water sources. 

Most importantly, the system streamlines the integration of data from multiple agencies, i.e., the system

integrates data for both contaminant sites and drinking water sources. This GIS will be used by a variety

of State agencies to better protect public drinking water wells and aquifers reasonably expected to be

used as drinking water from both motor vehicle fuel sources, including underground storage tanks

(operating sites and closed sites with existing contamination), and petroleum pipelines. Public access via

the Internet will serve to overcome current limitations on obtaining and sharing data among multiple

regulatory agencies, water purveyors, the petroleum industry, and other stakeholders. Furthermore, the

system gives all stakeholders access to on-line data analysis tools that can be used to estimate

vulnerability.

Other States are also developing and implementing GIS capabilities, although not as comprehensively as

California’s program.
86 This discussion refers specifically to the treatment of ground waters or surface waters intended for

distribution to consumers or to private well owners; remediation of ground water associated with contaminant sites

is addressed in the following section.

87 J.P. Malley, Jr., P.A. Eliason, and J.L. Wagler, “Point-of-Entry Treatment of Petroleum Contaminated Water

Supplies,” Water Environment Research, 1993, v. 65, no. 2, pp. 119-128.

50

VI. Treatment of Impacted Drinking Water86

When drinking water supplies become contaminated with MTBE, water suppliers must take steps to treat

the water so as to restore it to potable condition. The MTBE Research Partnership, which includes the

Association of California Water Agencies, the Western States Petroleum Association (WSPA), and the

Oxygenated Fuels Association (OFA), recently published Treatment Technologies For Removal of MTBE

From Drinking Water, a report reviewing and analyzing the costs of three water treatment technologies: 

air stripping; activated carbon; and advanced oxidation.

• Treatment of extracted air and water effluents is typically accomplished using air stripping, a

process in which contaminated water flows down a column filled with packing material while

upward-flowing air volatilizes the contaminant from the water. Although highly effective for

benzene, it is less effective and somewhat more costly for MTBE (e.g., 95 percent and higher

removal efficiency for benzene vs. 90 percent and higher for MTBE). Commonly, air stripped

effluent is “polished” to lower contaminant levels by subsequent treatment with activated carbon. 

& Activated carbon, or carbon adsorption, is also widely employed to remove low levels of organic

compounds from water by pumping it through a bed of activated carbon. Additionally, many

individual homeowners use small carbon canisters to remove a variety of contaminants, including

MTBE, from impacted private wells. Again, this process is highly effective for benzene, but

much less so for MTBE, which requires greater volumes of carbon per unit mass of MTBE

removed, and thus is significantly more expensive and less effective than benzene removal. 

& Advanced oxidation technologies use appropriate combinations of ultraviolet light, chemical

oxidants, and catalysts to transform contaminants. Oxidation technologies have been 

demonstrated to oxidize a wide range of organic chemicals, including MTBE. These same

technologies, especially air stripping and granular activated carbon (GAC), have been employed

successfully for use at individual homes with impacted drinking water wells.87

The costs associated with these types of treatment for drinking water are summarized in Figure 1.
88 National Toxicology Program, Summary of Data For Chemical Selection: Methyl Tert-Butyl Ether,

http://ntp-db.niehs.nih.gov/NTP_Reports/NTP_Chem_H&S/NTP_MSDS/HS_1634-04-4.txt

89 J.P. Salanitro et al., “Perspectives on MTBE Biodegradation and the Potential for in situ Aquifer

Bioremediation,” proceedings of the National Ground Water Association’s Southwest Focused Ground Water

Conference: Discussing the Issue of MTBE and Perchlorate in Ground Water (Anaheim, CA, June 3-4, 1998), pp.

40-54. 

51

TLK0399-.PRE D:\MTBE\REMOVAL 3/22/99

Air

Stripping

Ozone/

Hydrogen Peroxide

Granular

Activated Carbon

Annual MTBE Treatment Costs for a Family of Four

0

$50

$100

$150

$200

$250

$300

$350

$400 $391

$244

$122

$158

$54

$148

Cost per Family per Year

60 gpm

600 gpm

6,000 gpm

$86

$50 $42

Source: MTBE

Research

Partnership

Figure 1

Source: MTBE Research Partnership (Western States Petroleum Association, Association of California

Water Agencies, and Oxygenated Fuels Association), Treatment Technologies for Removal of Methyl

Tertiary Butyl Ether (MTBE) from Drinking Water -- Air Stripping, Advanced Oxidation Process (AOP),

and Granular Activated Carbon (GAC), Executive Summary, Sacramento, CA, December 1998.

Tertiary butyl alcohol (TBA) is another oxygenate that has been found at oxygenated gasoline release

sites. Because TBA is a byproduct of some MTBE production processes, TBA is found in some fuelgrade MTBE.88 TBA is also a metabolite of the biodegradation of MTBE.89 Because TBA is infinitely

soluble in water, use of air stripping and activated carbon treatment methods are even more limited than

for treatment of MTBE. TBA’s treatment by advanced oxidation may generate compounds potentially of

health and environmental concern. The presence of TBA will further limit the usefulness of the above

described technologies and increase treatment costs. 
90 U.S. Environmental Protection Agency, Office of Research and Development, Pump-and-Treat GroundWater Remediation: A Guide for Decision Makers and Practitioners, EPA/625/R-95/005, 1996.

52

VII. Remediation

A. MTBE

1. Risk Based Corrective Action

The following discussion focuses on the remediation of UST releases, as they are the predominant source

of higher levels of MTBE contamination and potential drinking water supply impacts. Releases from

other point sources of gasoline (e.g., ASTs and pipelines), however, would be managed in a similar

fashion. 

Regulatory policies have evolved during the last decade toward the increasing use of risk-based

corrective action (RBCA) programs. These programs serve as a means through which the management

of petroleum releases is prioritized so that time and resources can be directed to those sites most likely to

impact public or environmental health and safety. These changes in policies and practices are the result

of conclusive demonstrations of existing and innovative technologies’ limits in achieving complete

remediation of impacted ground water systems.90 The complex properties and interactions of gasoline

and hydrogeologic systems have been found to be substantial barriers to the effective removal of motor

fuel hydrocarbon masses released to ground water. The ascendancy of RBCA programs paralleled and

was assisted by an increased understanding of the role of natural attenuation and intrinsic bioremediation

in limiting the migration of dissolved hydrocarbon plumes. As a result, corrective action for many sites

now focuses first on removing any readily mobile hydrocarbon mass at the source, and then on managing

the dissolved plume using intrinsic bioremediation. Because MTBE is generally recalcitrant, the

presence of MTBE is expected to limit the utilization of intrinsic bioremediation as a remediation option. 

Although other natural attenuation processes may be used as deemed appropriate. 

The American Society for Testing and Material’s (ASTM) E 1739-95 Standard Guide for Risk Based

Corrective Action, developed during the early 1990's, forms the basis for most State risk-based programs. 

This RBCA guidance focuses on setting remedial goals based on health risks. MTBE also presents

aesthetic (i.e., taste and odor) problems at relatively low levels, which is currently not addressed by

ASTM RBCA. Alternative RBCA guidance would need to be developed to adequately address aesthetic

concerns. 

Methyl tertiary butyl ether is included in this guide as a compound of concern when evaluating impacts

from gasoline releases. The use of a risk-based framework places the emphasis on decisions that balance

cost, resource value, and risk to human health and the environment. Risk-based approaches seek to

implement management strategies that shift the focus of cleanup away from broadly defined cleanup

goals, which have been demonstrated to be technologically infeasible, and instead focus on a more

site-specific elimination or reduction of risk. It should be noted, however, that RBCA focuses on health

risks, and because MTBE has also been shown to present aesthetic (i.e., taste and odor) problems at

relatively low levels, alternative RBCA guidance may need to be developed to adequately address those

types of environmental concerns. 
91 The compounds benzene, toluene, ethyl benzene, and xylene are commonly known as “BTEX.”

92 U.S. Environmental Protection Agency, Office of Research and Development and Office of Solid Waste &

Emergency Response, Light Nonaqueous Phase Liquids, EPA Ground Water Issue Paper # EPA/540/S-95/500,

1995.

93 Daniel N. Creek and J. Davidson, “The Performance and Cost of MTBE Remediation,” National Ground

Water Association, 1998 Petroleum Hydrocarbons and Organic Chemicals in Ground Water, pp. 560-569;

Tom Peagrin, “Empirical Study of MTBE Benzene and Xylene Groundwater Remediation Rates,” National

Ground Water Association, 1998 Petroleum Hydrocarbons and Organic Chemicals in Ground Water, pp.551-559.

53

During the last several years, it has become an accepted practice at UST release sites to carefully

evaluate the potential for intrinsic remediation (i.e., bioremediation of the contaminant primarily by the

microbial population naturally present in the subsurface), and then to determine whether there is a need

for active remediation. The presence of MTBE can complicate the utilization of intrinsic remediation, as

although the BTEX91 plume may be shown to be contained satisfactorily, adequately demonstrating

stability and/or containment of an MTBE plume may be much more difficult. Methyl tertiary butyl ether

is generally recalcitrant, and therefore intrinsic remediation will typically not be a feasible option. 

Source control (i.e., removal of contaminant mass near the source of the release) is frequently employed

to reduce long-term impacts to ground water and drinking water in situations where intrinsic remediation

is not viable. After a release, non-aqueous phase liquid (NAPL) is likely to be present in the vadose

zone, capillary fringe, and ground water. The NAPL (e.g., gasoline) will act as a long-term source of

dissolved contaminants. Where practical, delineation and removal of NAPL are critical for complete

restoration of an impacted aquifer.92 In areas with shallow ground water, excavation of the NAPLcontaminated source area (down to and below the water table) can be an effective remediation approach. 

This technique is less effective at sites with extensive areal contamination, subsurface structures, or

deeper water tables. The excavation and disposal of large volumes of contaminated soil or aquifer

sediments have also been discouraged at many sites, in part because of limited solid waste treatment and

disposal facilities.

2. Conventional and Innovative Technologies

Although the conventional and innovative technologies used for ground water remediation of

nonoxygenated gasoline releases are also applicable for MTBE remediation, their relative effectiveness

and costs may vary depending on site-specific conditions.93 A remediation system typically employs airor water-based approaches for removing contaminants from the subsurface, and one or more treatment

technologies for removing the contaminant from those aqueous or vapor phase effluents. Alternatively,

in-situ techniques can be used to treat or destroy contaminants without bringing them above the surface. 

The applications of these technologies for MTBE and benzene are briefly compared below.

• Pump and treat is a mature, well-understood technology that pumps ground water

to the surface for subsequent treatment and discharge. Because of the relatively

low solubility of benzene, this technique is more effective as a benzene plume

migration control technology than for mass removal. MTBE’s high solubility

and low soil sorption should enable MTBE to be more readily extracted from an

aquifer than benzene. As with all pump and treat, the effluent will have to be

treated with technologies such as air stripping, advanced oxidation, GAC, or

bioreactor. 
94 R.C. Borden et al., “Intrinsic Biodegradation of MTBE and BTEX in a Gasoline-Contaminated Aquifer,”

Water Resources Research, 1997, v. 33, no. 5, pp. 1105-1115; A..M. Happel, B. Dooher, and E.H. Beckenbach,

“Methyl Tertiary Butyl Ether (MTBE) Impacts to California Groundwater,” presentation at MTBE Blue Ribbon

Panel meeting (March 1999); A.M. Happel et al., Lawrence Livermore National Laboratory. An Evaluation of

MTBE Impacts to California Groundwater Resources, UCRL-AR-130897, p.68 (June 1998); J.E. Landmeyer et al.,

“Fate of MTBE Relative to Benzene in a Gasoline-Contaminated Aquifer (1993-98),” Ground Water Monitoring &

Remediation, Fall 1998, pp.93-102; Mario Schirmer and J.F. Barker, “A Study of Long-Term MTBE Attenuation in

the Borden Aquifer, Ontario, Canada,” Ground Water Monitoring & Remediation, Spring 1998, pp. 113-122; Reid,

J.B., et al., “A Comparative Assessment of the Long-Term Behavior of MTBE and Benzene Plumes in Florida,” pp.

97-102 Natural Attenuation of Chlorinated Solvents, Petroleum Hydrocarbon and Other Organic Compounds

(1999); Hurt, K.L., et. al., “Anaerobic Biodegradation of MTBE in a Contaminated Aquifer..,” pp. 103-108, Natural

Attenuation of Chlorinated Solvents, Petroleum Hydrocarbon and Other Organic Compounds (1999); Bradley,

P.M., et.al., Aerobic Mineralization of MTBE and tert-Butyl Alcohol by Stream-bed Sediment Microorganisms:

(continued...)

54

• Soil vapor extraction (SVE) pulls air through the soil to volatilize contaminants. 

Because MTBE does not adsorb strongly to soils and has a higher vapor pressure

than benzene, MTBE will readily volatilize from gasoline in soils. When MTBE

is dissolved in soil moisture, however, SVE will not remove MTBE, which is

highly soluble.

• Air sparging injects air below the water table to volatilize contaminants from

ground water. Compared with BTEX, a much larger flow of air is required to

volatilize a similar mass of MTBE. This addition of air/oxygen also enhances

biodegradation of contaminants that are aerobically degraded by native

microorganisms. Although air sparging will readily enhance the biodegradation

of benzene, studies to date have shown MTBE to be relatively recalcitrant to

biodegradation by native populations of microbes in the subsurface. Therefore,

although air sparging is known to be an effective technology for remediating

benzene (increases volatilization and biodegradation), it is expected to be less

effective and more costly for MTBE remediation (i.e., dissolved phase does not

volatilize and may be relatively recalcitrant to native biodegradation). Air

sparging is frequently teamed with SVE to capture the volatilized compounds.

• Dual phase extraction involves vapor extraction and ground water extraction in

the same well. This technique is likely to be most effective in situations in

which the water table can be lowered, allowing for a larger area of influence for

the vapor extraction system. As discussed above, when MTBE is dissolved in

soil moisture, vapor extraction will not effectively remove MTBE, which is

highly soluble. Therefore, this technique is most effective for volatilizing

MTBE from gasoline. 

• Bioremediation of MTBE contamination is an increasingly active area of

research. The biodegradability of MTBE is considered to be much slower

relative to the abundant natural bioremediation of other gasoline constituents in

the subsurface (e.g., benzene), and MTBE generally has been recalcitrant or

limited relative to benzene biodegradation in field samples, although there is

some field evidence to the contrary.94 Recent lab and field studies have
94 (...continued)

Envtl. Sci. Tech., v. 33 no. 11, pp. 1877-1897 (1999).

95 Depending on the precise circumstances, these costs can range from moderately higher than BTEX-related

costs to significantly higher. 

96 These levels are addressed in the permits issued by the appropriate regulatory authorities for these

discharges.

55

indicated that biodegradation processes can be accelerated by augmenting the

subsurface environment or microbial population (e.g., by the addition of oxygen,

microbes, nutrients, or hydrocarbons that stimulate MTBE cometabolism). 

• In-situ oxidation relies on the capacity of certain chemical mixtures (e.g.,

hydrogen peroxide combined with iron) to rapidly oxidize organic molecules

such as MTBE in water. Because MTBE oxidizes rapidly, it will be removed

during the course of routine water treatment by this technique. Although current

use of this technology is limited, when subsurface conditions and contaminant

distribution are favorable, it has been demonstrated to effectively remove both

MTBE and conventional gasoline components. 

3. Treatment of Remediation Effluent 

Treatment of the air and water effluents extracted from the above processes is typically accomplished

using the same processes described previously for drinking water treatment (air stripping, activated

carbon, and oxidation). Again, these processes are highly effective for benzene, but less so for MTBE. 

The costs associated with the treatment of effluents with MTBE are thus likely to be somewhat higher

than for BTEX.95 Catalytic or thermal oxidation technologies are also commonly used for air phase

effluents, and MTBE again poses a more difficult and costly problem than benzene. Fluidized

bioreactors are less commonly employed, as they require somewhat more complex operation and

maintenance. They typically use activated carbon to support microbial growth so that contaminants are

adsorbed onto the carbon and destroyed by resident microbes as the contaminants pass through the unit. 

This technology is somewhat more elaborate than air stripping and carbon adsorption, but may grow in

acceptability if reliable MTBE treatment can be documented. In general, MTBE-BTEX effluents will be

more costly to treat and discharge than BTEX alone. Synthetic Resin Adsorbents, which exhibit a much

higher adsorbent capacity for MTBE relative to activated carbon, are currently available. With additional

research, they may become a viable cost effective treatment.

4. Incremental Costs for MTBE Remediation

A certain level of remediation activity/corrective action is required for almost every release of gasoline,

with or without oxygenates. Evaluation of the incremental remediation costs of MTBE contamination is

a difficult task because of the numerous site-specific variables to address. Four key variables include (1)

the cleanup target established for the site; (2) allowable MTBE discharge levels in the water and vapor

effluents generated during the remediation process;96 (3) the size of the dissolved plume; and (4) the

potential for using natural attenuation as the treatment technology.
97 Robert Hitzig, Paul Kostecki, and Denise Leonard, “Study Reports LUST Programs are Feeling Effects of

MTBE Releases,” Soil & Groundwater Cleanup, August-September 1998, pp. 15-19. 

98 The UC Study, Health and Environmental Assessment of MTBE, evaluated costs of remediation of MTBE

sites in California based on industry, regulatory data and studies of MTBE impacts to groundwater in California. 

Overall, this study concluded that on average MTBE contaminated sites may be 1.4 times more costly to remediate

than conventional gasoline sites. 

99 U.S. Environmental Protection Agency, Draft Memorandum from Timothy Fields, Jr., Acting Assistant

Administrator, Office of Solid Waste and Emergency Response, “Use of Monitored Natural Attenuation at

Superfund, RCRA Corrective Action, and Underground Storage Tank Sites,” June 9, 1997.

56

Clearly, it will be more expensive to reach an MTBE ground water cleanup goal of 15 ppb than a goal of

40 ppb or higher. Similarly, the related effluent treatment costs will be much higher if permitted water

discharge levels are 35 ppb as opposed to 500 ppb, and daily volatile organic compounds (VOC)

discharges to the atmosphere are limited to 2 pounds compared with 50 pounds. As there are no national

standards for MTBE, it is not possible to estimate these incremental costs. 

The U.S. Environmental Protection Agency has surveyed UST program managers to obtain some initial

estimate of increases in remediation cost.97 Although the survey data have a high degree of uncertainty

and should be viewed as preliminary, the EPA survey estimated that perhaps 75 percent of MTBEimpacted UST sites would have remediation costs less than 150 percent of the cost of typical BTEX sites,

and that many MTBE sites might have no additional cost. The Leaking Underground Storage Tank

(LUST) program managers estimated that the remaining 25 percent of sites would cost greater than 150

percent of representative BTEX sites, with perhaps 5 percent costing in excess of 200 percent more than

typical BTEX sites. The UC study, Health and Environmental Assessment of MTBE, evaluated costs of

remediation of MTBE sites in California based on industry, regulatory data and studies of MTBE impacts

to groundwater in California. Overall, this study concluded that on average MTBE contaminated sites

may be 140 percent of the cost of remediating conventional gasoline sites.98 

Remediating MTBE plumes can be roughly comparable to the cost of conventional BTEX treatment for

equivalent plume sizes, assuming the permitted MTBE effluent treatment and discharge levels allow

standard air stripping and carbon adsorption approaches to be used. However, because an MTBE plume

is more likely to become larger than typical benzene plumes when release detection is delayed, if

dissolved MTBE source zone concentrations are much higher than BTEX (as they might be from a

release of an RFG), or if stringent MTBE effluent discharge levels are applied, remediation costs are

expected to increase proportionately. Absent active remediation or sufficient intrinsic bioremediation to

prevent further migration, MTBE plumes are expected to extend further, perhaps by a large extent, than

the companion benzene plumes.

This potential difference between benzene and MTBE plume lengths may influence remediation costs in

another way. Monitored natural attenuation (MNA) is a widely accepted, cost effective approach to

managing benzene plumes.99 If MTBE plumes are expected to migrate further because of higher source

area dissolved concentrations and exhibit limited biodegradation as compared to benzene, then fewer

sites may be able to use MNA as an acceptable remediation option (i.e., active remediation would be

required, thus increasing cleanup costs). Only a limited number of field studies have been conducted to
100 R.C. Borden et al., “Intrinsic Biodegradation of MTBE and BTEX in a Gasoline-Contaminated Aquifer,”

Water Resources Research, 1997, v. 33, no. 5, pp. 1105-1115; J.E. Landmeyer et al., “Fate of MTBE Relative to

Benzene in a Gasoline-Contaminated Aquifer (1993-98),” Ground Water Monitoring & Remediation, Fall 1998,

pp.93-102; Mario Schirmer and J.F. Barker, “A Study of Long-Term MTBE Attenuation in the Borden Aquifer,

Ontario, Canada,” Ground Water Monitoring & Remediation, Spring 1998, pp. 113-122.

101 Arturo Keller, Ph.D., et.al., Executive Summary, Recommendations, Summary, “Health and Environmental

Assessment of MTBE,” 1999.

102 Malcome Pirnie, Inc., Evaluation of the Fate and Transport of Ethanol in the Environment, (Oakland, CA: 

Malcome Pirnie, Inc.), 1998; H.X., Corseuil et al., “The Influence of the Gasoline Oxygenate Ethanol on Aerobic

and Anaerobic BTX Biodegradation,” Wat. Res., 1998, 32, 2065-2072.; C.S. Hunt et al., “Effect of Ethanol on

Aerobic BTX Degradation Papers from the Fourth International In Situ and On-Site Bioremediation Symposium,”

Battelle Press, April-May 1997, pp. 49-54.

103 Michael Kavanaugh and Andrew Stocking, “Fate and Transport of Ethanol in the Environment,”

presentation at the May 1999 MTBE Blue Ribbon Panel meeting. [Based on Malcome Pirnie, Inc. Evaluation of

the Fate and Transport of Ethanol in the Environment (Oakland, CA, 1998.)]

57

evaluate MTBE natural attenuation;100 thus, it is difficult to assess fully the potential future costs. A

recent study estimated that while over 80 percent of non-MTBE conventional gasoline sites might utilize

MNA, few MTBE sites would be able to, resulting in substantially higher cleanup costs for MTBE

sites.101

B. Ethanol 

The above discussions are focused on remediation issues identified for MTBE. It is difficult to make a

comparative assessment of MTBE versus ethanol gasoline releases, as there is relatively little field data

characterizing the behavior of ethanol gasoline releases.102 Monitoring for ethanol is not required at UST

sites, even in Midwestern States that use large volumes of ethanol. Additionally, standard EPA methods

used to analyze fuel hydrocarbon compounds are not technically appropriate for detection and

quantification of ethanol below the 1 part per million (ppm) to 10 ppm range. Ethanol is known to be

much more biodegradable than benzene. Although ethanol is likely to biodegrade rapidly in ground

water, because ethanol is infinitely soluble in water, much more ethanol will be dissolved into water than

MTBE. It is not known how long it may take to biodegrade large amounts of dissolved ethanol. 

Laboratory research suggests that microorganisms prefer to biodegrade ethanol over other fuel

components, so that ethanol biodegradation consumes all available oxygen and depletes other electron

acceptors needed for biodegradation, thus delaying the onset, and potentially slowing the rate, of BTEX

biodegradation. Although the magnitude of this effect is presently unknown, it is expected to result in

somewhat longer BTEX plumes at gasoline release sites.103 Because ethanol is most commonly blended

at distribution terminals, releases of neat (pure) ethanol may occur at those facilities, requiring

remediation. The extent of any current possible problem and cost associated with such clean up is

unknown.

C. Funding
104 See EPA OUST’s Publication on Sources of Financial Assistance for Underground Storage Tank Work. 

The document entitled "Financing Underground Storage Tank Work: Federal and State Assistance Programs" lists

Federal and State programs that provide money to assist in upgrading or replacing underground storage tanks, 

conducting investigations, and performing remediation. This document provides information on financial assistance

available to municipalities, State or local governments, non-profits, private UST owners or operators, and for tanks

on Native American or tribal lands. The assistance is available in the form of direct loans, loan guarantees, grants,

or interest subsidies. The publication also describes some of the available State financial assistance programs. 

Eighteen States have active financial assistance programs for UST upgrades and replacement; some of these

programs also offer assistance cleaning up UST releases. Also, see the ASTSWMO Report, “State Leaking

Underground Storage Tank Financial Assurance Funds Annual Survey Summary,” June 1998.

Http://www.astswmo.org/Publications/pdf/98vtsum.pdf.

105 U.S. Environmental Protection Agency, State Assurance Funds: State Funds in Transition Models for

Underground Storage Tank Assurance Funds, 1997, EPA 510-B-97-002,

www.epa.gov/swerust1/states/fundinfo.htm.

106 Executive Office of the President of the United States, Budget of the United States Government, Fiscal

Year 2000 – Appendix, 1999, p. 937.

107 Fiscal year 1998 (actual) and 1999 (estimated) appropriations from the LUST Trust Fund were $65 million

and $73 million, respectively. (See Executive Office of the President of the United States, Budget of the United

States Government, Fiscal Year 2000 – Appendix, 1999, p. 937.)

58

1. State and Federal Sources104

The primary sources of funding for UST remediation are State UST cleanup funds.105 State cleanup

funds raise and expend about $1 billion annually, by far the largest source of funding available to pay for

remediation of MTBE-contaminated soil and ground water. The second largest source of funding is

private insurance. Most owners and operators have the required financial assurance coverage provided

by State funds. Owners and operators in States without State funds, or in those States in which State

funds are transitioning and not providing coverage for new releases, must meet their UST financial

responsibility requirements by other mechanisms, most commonly UST insurance provided by private

insurers. According to the insurance industry, roughly 10 percent to 15 percent of USTs are currently

covered by private insurance. This percentage is likely to increase as more States transition out of their

UST cleanup funds. 

The Federal LUST Trust Fund is supported through a 0.1 cent per gallon Federal tax on motor fuels that

expires after March 30, 2005. At the end of fiscal year (FY) 1998, the Trust Fund had a balance of

approximately $1.2 billion. In FY 1998, the Fund received approximately $203 million in new monies –

$136 million from the Federal tax and $67 million in interest on the Fund’s balance. In FY 1999, new

receipts are expected to increase to $278 million ($212 million from the tax and $66 million in interest),

raising the Fund’s balance to approximately $1.4 billion (after FY 1999 appropriations).106 Monies in

this fund are subject to appropriation, and Congress has been appropriating approximately $70 million

annually in recent years.107 Approximately 85 percent of the appropriated funds are given to the States to

administer and enforce their LUST programs and to pay for remediation of eligible releases. The States

use approximately two-thirds of the funds to support staff who oversee and enforce cleanups by

responsible parties. Approximately one-third of the funds are used to pay for cleanups in which the

owner and operator are unknown, unwilling, or financially unable to undertake and to complete cleanup
108 If the owner or operator is financially able, but otherwise unwilling to cleanup the site, the implementing

agency is responsible for recovering the costs of remediating the site.

59

of a contaminated site.108 The law establishing the LUST Trust Fund places clear responsibility for

remediation on owners and operators and places significant eligibility requirements on the use of LUST

Funds for actual cleanup of contaminated sites. 

2. Recovery of Funds from Potentially Responsible Parties 

Water suppliers can face substantial expenditures for either replacement water supplies or treatment of

contaminated waters. For example, the City of Santa Monica lost 50 percent of its existing water supply

in 1996 as the result of MTBE impacts. The annual costs of the required volume of replacement water

(more than 6 million gallons per day) are estimated at approximately $4 million. Although these costs

are the full responsibility of the party shown to be liable for the contamination, establishing such liability

may take months or years. It has been suggested that a funding mechanism should exist for covering

these unexpected costs. 

3. State Water Supply Revolving Funds

Other potential funding sources for addressing MTBE contamination are the Clean Water State

Revolving Fund (CWSRF) and Drinking Water State Revolving Fund (DWSRF) programs. These

programs were established to provide States with a continuing source of funding to address (1)

wastewater treatment, nonpoint source, and estuary activities (CWSRF); and (2) drinking water

treatment, source water protection, and water system management activities (DWSRF). Funding

decisions for projects and activities are made by each State, pursuant to eligibility guidelines provided by

EPA. 

The CWSRF can be used for site mitigation efforts to address MTBE releases to the extent that such

activities are included in an EPA-approved State nonpoint source management program. To date, three

States (Delaware, Nebraska, and Wyoming) have provided a total of approximately $48 million in

CWSRF loans to about 1,200 sites for removing underground tanks and purchasing release detection

systems. In these three States, the CWSRF program works in partnership with the State's Leaking

Underground Storage Loan Program to provide technical assistance and funding support to potential loan

recipients. Funds available to address problems related to MTBE may increase as States expand use of

their CWSRF programs to address nonpoint source problems.

Although the DWSRF cannot be used to fund remediation efforts, States can loan DWSRF monies to

public water systems for the installation of treatment equipment to address contaminated source water

entering the treatment plant. In addition to providing loan assistance to public water systems for eligible

projects, the DWSRF also allows each State to reserve up to 31 percent of its grant to fund programs and

activities that enhance source water protection and water systems management. Several of the activities

eligible under the reserves could address protection and management issues associated with MTBE. 
60

4. Alternative Water Supply Funding Mechanism

The above discussion has reviewed a variety of existing potential sources of funds available to replace or

treat public and private water systems. Should these sources not meet existing needs adequately, an

alternative funding approach may be required. To simultaneously provide a source of funding for

emergency alternative supplies and treatment of impacted public water systems, and to act as a gradual

disincentive for use of MTBE, a tax/surcharge could be levied on MTBE production for use in gasoline. 

These levied monies could then be made readily accessible by public and private water suppliers to

reimburse incurred expenses associated with addressing MTBE contamination incidents. The economic

viability and amount of this surcharge would need to be determined, but would likely range from 5

percent to 50 percent of the price of each gallon of MTBE sold. For example, a 10 percent surcharge

with an MTBE price of $0.70 per gallon and RFG with 11 percent by volume MTBE would add about 1

cent to the per gallon-price of RFG and would accumulate about $300 million annually with current

MTBE usage. This surtax could also be structured to increase over time to further discourage MTBE

use. 
109 Moreover, if all refineries and terminals require capital upgrades, the construction industry may become

strained.

61

D. Fuel Supply and Cost

I. Introduction

The current U.S. fuel supply system is a finely balanced network that depends on crude oil supply,

refinery production, unimpeded pipeline and marine movements, and strategically sited commercial

stocks to protect against market volatility. Recent accident- and weather-related refinery and pipeline

outages (e.g., incidents in California and Washington State) demonstrate the system’s delicate nature. 

As such, changes in fuel regulatory requirements, with their attendant capital investment needs and

infrastructure changes, must be implemented without introducing unnecessary volatility. Disruptions to

the nation’s fuel supply system result in price volatility and increased costs to consumers. Therefore, any

proposed changes to U.S. fuel requirements should consider the following:

& The time required to implement capital investments in both refineries and infrastructure,

which entails raising capital, obtaining permits, and constructing units and

infrastructure.109

& The need for regulatory certainty to provide industry with sufficient lead time to make all

necessary changes. Regulatory uncertainty increases investment risks and forces

industry to postpone investments to the last minute.

& The need for regulatory flexibility in achieving targeted goals. The petroleum industry is

diverse, and what is optimal for one sector may not be optimal for another.

& The need for fungibility in the system. At present, the U.S. fuel supply system works

well, as most requirements tend to be national (e.g., low sulfur on-road diesel) or

regional (e.g., reformulated gasoline or California reformulated gasoline). Once small

areas begin requiring unique fuels, however, the system operates at sub-optimal

efficiency, costs to consumers increase, and fuel supplies are more vulnerable to

volatility.

This combination of sufficient time, regulatory certainty and flexibility, and fungibility will facilitate a

smooth transition, thus avoiding excessive cost increases driven by unnecessary stress to the system. 

An important consideration in this discussion is the regulatory status of methyl tertiary butyl ether

(MTBE). If the use of MTBE (and other ethers) is reduced substantially or phased out, but the oxygenate

requirement is maintained, ethanol (and possibly other alcohols) will remain as the only alternatives. At

present, however, ethanol is produced primarily in the Midwest and is not manufactured in sufficient

volume to meet national demand. Although new ethanol production capacity can be brought on-line in

two years, the permitting and construction of necessary infrastructure will be a critical determinant of

ethanol’s availability and cost.
110 U.S. Energy Information Administration, Petroleum Supply Annual 1998, Volume I, Table S4, p. 17, June

1999.

111 U.S. Energy Information Administration (T. Litterdale and A. Bohn), Demand and Price Outlook for

Phase 2 Reformulated Gasoline, 2000, April 1999, pp. 7-8.

112 California Energy Commission, Supply and Cost Alternatives to MTBE in Gasoline, October 1998.

113 Downstream Alternatives, Ethanol Supply, Demand, and Logistics: California and Other RFG Markets,

May 1999.

62

II. Industry Overview

A. Consumption 

1. Consumption of Gasoline and Oxygenates

Current consumption of gasoline in the United States is approximately 8.3 million barrels per day (b/d),

or approximately 126.5 billion gallons annually.110 Based on Federal fuel supply data, total U.S.

oxygenate demand was approximately 370,000 b/d in 1997 (refer to Table D1 in this section’s

Appendix).111 Excluding the volume of oxygenate used only for octane purposes, the average 1997

demand for oxygenates in reformulated gasoline (RFG) and oxygenated gasoline in environmental

control areas was approximately 265,000 b/d, 41,000 b/d, and 17,000 b/d per day for MTBE, ethanol, and

other ethers, respectively. Thus, although making up less than 5 percent of total national gasoline

consumption, MTBE and other ethers met approximately 87 percent of the oxygenate volume

requirement in 1997.

2. Meeting California’s Ethanol Demand

A recent study funded by the Renewable Fuels Association (RFA), The Use of Ethanol in California

Clean Burning Gasoline, estimates that if MTBE was banned, California would demand 41,000 b/d of

ethanol in order to meet the oxygenate volume in the mandated areas plus 30 percent penetration into the

non-mandated areas. A study by the California Energy Commission (CEC), however, estimates 75,000

b/d in demand for similar requirements.112 According to the RFA report, California’s demand could be

met from currently underutilized production, which equates to 29,000 b/d with 100 percent utilization,

and new plant start-ups. The balance would be made up by ethanol redirected from the octane

enhancement markets and increased imports.113
114 Roger Conway, “Ethanol and Its Implications for Fuel Supply,” presentation at the April 1999 MTBE Blue

Ribbon Panel meeting; Downstream Alternatives, Ethanol Supply, Demand, and Logistics: California and Other

RFG Markets, May 1999.

115 This figure is the result of the following calculations: (1) Calculate the total ether supply for RFG and

oxygenated fuels in 1997: 265,000 b/d + 17,000 b/d = 282,000 b/d; (2) Multiply 282,000 b/d by 0.52 to adjust for

the oxygen equivalency of ethanol = 146,640 b/d; and (3) Add 41,000 b/d to include the current volume of ethanol

utilized for RFG and oxygenated fuels, thus reaching a total of 187,640 b/d (refer to Table D1 in the Appendix). 

116 Jack Huggins, Submitted written comments on behalf of the Renewable Fuels Association at the April 1999

MTBE Blue Ribbon Panel meeting. 

117 Roger Conway, “Ethanol and Its Implications for Fuel Supply,” presentation at the April 1999 MTBE Blue

Ribbon Panel meeting; Downstream Alternatives, Ethanol Supply, Demand, and Logistics: California and Other

RFG Markets, May 1999.

118 Stephen Gatto, presentation on BC International Corporation at the April 1999 Blue Ribbon Panel meeting;

Roger Conway, “Ethanol and Its Implications for Fuel Supply,” presentation at the April 1999 MTBE Blue Ribbon

Panel meeting.

63

B. Ethanol Production

Current U.S. ethanol production capacity is estimated at 120,000 b/d114, which is equivalent in oxygen

content to approximately 230,000 b/d of MTBE. In order for ethanol alone to fulfill the nationwide

oxygen requirement in all RFG and oxygenated fuels areas, the U.S. Environmental Protection Agency

(EPA) estimates that approximately 187,000 b/d of ethanol would be needed, assuming that no ethanol is

used for economic octane blending.115 Thus, in a scenario of complete MTBE removal, an estimated

additional 67,000 b/d of ethanol would be needed to fulfill the required oxygenate volume nationwide. 

Ethanol supply could be fulfilled by a combination of imports and additional production capacity created

by removing bottlenecks at existing plants and by building new facilities. The ethanol industry estimates

that the current expansion of existing ethanol-from-corn production facilities may increase production

capacity by as much as 40,000 b/d. Additionally, new ethanol production facilities currently being

planned could provide another 25,000 b/d (new ethanol plants may take two or more years to build).116

The U.S. Department of Agriculture (USDA) estimates that 5 percent of the total corn utilized in 1997-98

was for fuel ethanol production.117 

Ethanol production from biomass processing is currently about 60 million gallons per year (equivalent to

approximately 4,000 b/d). Estimates from the USDA indicate that assuming favorable economics, the

resource base for ethanol from biomass could reach approximately 10 billion gallons annually

(approximately 650,000 b/d) after 2025.118 Recently, on August 12, 1999, President Clinton issued an

executive order to initiate a government effort to develop a biomass research program. The goal of the

program is to triple the use of bioenergy and bioproducts by 2010, which includes the production of clean

fuels such as ethanol and other products. 

Based on total gasoline regulated properties, ethanol used at 5.7 percent by volume to meet the 2.0

percent by weight (wt.%) oxygen requirement in RFG will not be able to replace all of the 11 percent by

volume of MTBE in RFG. In California, some refiners have stated that they must remove some volume

of butanes/pentanes from California Phase 2 RFG in order to accommodate the increase in gasoline's

Reid vapor pressure (RVP) with the addition of ethanol, and thus must significantly expand their crude
119 Al Jessel, Chevron Products Company, “Fuels Regulations and Emissions Technology,” presentation at the

March 1999 MTBE Blue Ribbon Panel meeting. See also, Duane Bordvick, Tosco Corporation, “Perspectives on

Gasoline Blending for Clean Air,” presentation at the March 1999 MTBE Blue Ribbon Panel meeting. 

120 U.S. Department of Energy, Estimating the Refining Impacts of Revised Oxygenate Requirements for

Gasoline: Summary Findings, May 1999.

121 Al Jessel, Chevron Products Company, “Fuels Regulations and Emissions Technology,” presentation at the

March 1999 MTBE Blue Ribbon Panel meeting.

122 Downstream Alternatives, Ethanol Supply, Demand, and Logistics: California and Other RFG Markets, 

May 1999. 

123 42 gallons = 1 barrel

124 Based on API confidential communications with rail car lessors, 1999.

64

oil-based RFG production capacity by the full 11 percent by volume lost by removing MTBE.119

Although this Panel did not investigate the effect that the loss of MTBE would have on refineries outside

of California, there are some similarities and a number of differences in refinery processes that, on

balance, result in similar volume shortfalls in blending component capacities during the summer seasons.

A similar analysis by the U.S. Department of Energy (DOE) also concluded that additional supply would

be necessary under an ether ban in the Northeast, requiring increased domestic supply or foreign

imports.120

C. Ethanol Infrastructure/Transportation

Because ethanol is soluble in water, which is commonly found in pipelines and storage tanks associated

with the gasoline distribution system, and will separate from gasoline, ethanol is usually blended at the

distribution terminal.121 Therefore, because most of the nation’s ethanol is produced in the Midwest, the

ethanol would have to be transported to terminals for blending through a dedicated (ethanol-only)

pipeline, by rail, by marine shipping, or by some combination of these methods. Transportation from the

Midwest to the Northeast and the West is challenging and will likely be costly and transportation-facility

intensive. 

A study122 estimates that approximately 1,982 rail cars (30,000-gallons123 each) would be necessary to

supply the California market with ethanol for RFG purposes, assuming only rail transport. Given the

range in ethanol demand projected by the CEC study (35,000 b/d to 92,000 b/d), this rail car estimate

could actually be more than double. The existing fleet of 30,000-gallon rail cars is between 8,000 and

10,000, nearly all of which are currently unavailable for ethanol transport due to prior leasing

commitments. With existing manufacturing capability, it is estimated that approximately 1,000

additional (30,000-gallon) rail cars could be built per year.124 

In California, marine transport has been found to cost approximately the same as rail transport, although

in certain instances marine shipping can be slightly cheaper. Surveys of terminal operators in California

have indicated that a large portion of product (most likely at least 50 percent) would be shipped as

waterborne cargo. Some California operators have stated that the large size of marine cargoes makes it

preferable to spotting, inspecting, and unloading numerous rail cars. Moreover, in the Northeast, nearly
125 Letter to Daniel Greenbaum from Robert E. Reynolds, President, Downstream Alternatives, Inc., June 24,

1999. See also, Downstream Alternatives, Ethanol Supply, Demand, and Logistics: California and Other RFG

Markets, May 1999. 

126 Oil and Gas Journal, California refiners anticipate broad effects of possible state MTBE ban, January 18,

1999.

127 Dexter Miller, “Alkyates, Key Components in Clean-Burning Gasoline,” presentation at the May 1999

MTBE Blue Ribbon Panel Meeting.

65

every terminal location is accessible by water, whereas only a few can be accessed by rail. As such,

some estimate that 60 percent of the Northeast’s total demand would be met through ship and oceangoing barge transport.125

These will also be cited to develop the necessary blending and distribution infrastructure to deliver

ethanol-based RFG to retail outlets. Ethanol requires blending much further down the distribution

channel (at the truck-loading point) than does MTBE (at the refinery terminal). The infrastructure to

support such blending on a wide scale does not currently exist.126

D. Producing Non-Oxygenate Alternatives

In the event of an MTBE phase down with oxygenate flexibility, refiners have a number of blending

options to meet RFG performance standards, including increased use of alkylates, aromatics, and perhaps

other fuel blending streams derived from petroleum.127 Each refinery has a uniquely optimal mode of

operation, facility selection, and size, all of which are currently balanced for MTBE use. Without

MTBE, refiners would have to determine their most economic mode of operation and also determine

which new facilities and technologies would provide the economic return on investment that shareholders

require for continued investment. The strategy of total alkylate replacement is expensive (possibly

exceeding $1 billion), may not fully meet octane needs, and demands other operational trade-offs in the

refinery and/or additional supply of isobutane and olefin feedstocks. Although aromatics can also be

produced in greater volume and will provide higher octane, higher aromatics use will also increase toxics

emissions so that aromatics cannot likely fulfill all non-oxygenate needs. Nevertheless, oxygenate

flexibility is an important component of the solution to removing MTBE from the system in a timely

manner since it increases refiner flexibility in meeting RFG performance standards. The Panel could not

conduct a comprehensive evaluation of the technologies, facilities, and strategies necessary to achieve a

new, economically optimal fuels refining industry without MTBE, and with or without the current

oxygenate requirements, but rather chose to rely on analyses by others to estimate likely effects on

supply and cost, as discussed in Section III below.
128 U.S. Department of Energy, Estimating the Refining Impacts of Revised Oxygenate Requirements for

Gasoline: Summary Findings, March 1999; California Energy Commission, Supply and Cost Alternatives to MTBE

in Gasoline, October 1998; Robert Cunningham, “Costs of Potential Ban of MTBE in Gasolines,” presentation at

the March 1999 MTBE Blue Ribbon Panel meeting.

129 Sunoco, Time Required to Complete Desulfurization, personal communication.

66

III. Impact of Fuel Requirement Changes on Supply

A. Overview

The impact of a change in fuel requirements (e.g., reduction in the use of oxygenates or of a particular

oxygenate) on fuel availability and cost will depend primarily on the following factors: 

& The time available for a transition and the availability of adequate and sustained

supplies of any new component, and the time required for permitting and

achieving compliance with applicable regulations;

& Regulatory certainty and flexibility regarding fuel specifications;

& The degree to which fuel changes are national, regional, or state-by-state in

scope, i.e., fungibility; 

& Additional capital costs (e.g., new refinery facilities) and/or operating costs (e.g.,

transportation and distribution costs); and 

& The cost of replacing octane while continuing compliance with environmental

standards.

B. Time

Government agencies and fuel refiners/marketers have stated that without adequate lead time, rapid

reductions in the volume of MTBE allowed in the gasoline supply stream will have an immediate and

negative effect on regional markets as well as the nation’s ability to meet gasoline demand.128

In general, refineries must undergo a stepwise process to implement major changes in fuel processing,

such as desulfurization or oxygenate reduction. A summary of Sunoco’s recent analysis of the process

time required to comply with future sulfur limits is show in Table 1 as a general guide to such capital

projects.129 (Actual time requirements will vary from refinery to refinery.) 
130 California Energy Commission, Supply and Cost Alternatives to MTBE in Gasoline, October 1998. This

study did not analyze the likely fuel supply impacts to areas outside of California if MTBE use were to be phased

out in California.

67

Table 1. Sample Process Timetable for Complying with Future Sulfur Limits in the Refining

Industry

I. Conceptual/Process Feasibility

& Identify purpose, scope, and permits required

& Produce cost estimates

& Management approval

7 months

II. Process/Project Scope Definition

& Develop scope, equipment requirements,

project milestones, and construction strategies

& Produce more accurate budget estimates 

& Management approval

8 months

III. Preliminary Engineering

& Select engineering contractor 

& Submit permit applications 

& Conduct design review

& Issue master schedule 

& Submit costs for approval

12 months

IV. Detailed Project Execution

& Procure materials 

& Receive all permits

& Award contracts

& Construction

& Testing

& Training 

& Start-up

21 months

Total 48 months

 Source: Sunoco

Should ethers, particularly MTBE, be phased out in California, the CEC estimates that in three years

California refineries would require as much as 75,000 b/d of ethanol and up to 142,000 b/d of additional

gasoline imports to meet demand.130

The U.S. Department of Energy estimates that if regulation changes are finalized, four years would be

needed to allow for new construction of refineries and for ethanol production, transportation, loading and

unloading capacities to increase. Under this assumption, a scenario of an ether phase-out should not
131 U.S. Department of Energy, Estimating the Refining Impacts of Revised Oxygenate Requirements for

Gasoline: Summary Findings, March 1999; Downstream Alternatives, Ethanol Supply, Demand, and Logistics:

California and Other RFG Markets, May 1999.

132 California Energy Commission, Supply and Cost Alternatives to MTBE in Gasoline, October 1998.

133 Office of Science and Technology Policy, National Science and Technology Council, Interagency

Assessment of Oxygenated Fuels, June 1997.

68

cause supply problems in Petroleum Administration for Defense District (PADD) I, the East Coast.131

This analysis did not consider effects on regional supplies in the event of a national MTBE ban or other

changes in fuel properties (i.e., sulfur reductions).

Relative to California refiners, the transition to a non-ether RFG would be more difficult and require

more time for non-California refiners. Implementation of the proposed sulfur rules (TIER 2) will have

less impact on California refiners, as all California RFG (CaRFG) is already at a sulfur level of 30 parts

per million (ppm) or lower. Other refiners will need additional time to build adequate desulfurization

units, as well as other facilities needed to generate the octane lost through desulfurization. The State of

California believes that with a repeal of the Federal oxygen mandate, MTBE should be phased out in

three and one-half years.132

C. Certainty

Refiners/marketers have stated that regulatory certainty is necessary to insure low-risk capital investment

in alternatives to our current fuel supply system. For example, whether the current oxygenate mandate

will remain or be removed will be a critical factor in future refinery, product transportation, and

marketing terminal construction decision making. Refiners/marketers believe that the removal of the

oxygenate mandate would provide maximum flexibility for the individual decisions necessary for each

refiner to meet all Federal and State RFG performance standards.

D. Fungibility

Refiners/marketers have indicated that to meet consumer fuel demand and to minimize supply shortages,

the scope of any future fuel changes should be national or regional. Permitting state-specific fuel

changes (e.g., low RVP, low sulfur) may lead to greater uncertainty in fuel supply and may cause

periodic shortages unless there is a mechanism to ensure consistency across state boundaries.

Although ethanol blended gasoline can be blended to maintain low vapor pressure, reformulated gasoline

made with ethanol will likely increase evaporative emissions when commingled with other fuels in

markets where ethanol occupies 30 percent to 50 percent of the market.133 (Refer to Issue Summary B,

“Air Quality Benefits”). In order to minimize commingling, refiners in these markets will need to

develop and use infrastructure (storage, trucks, etc.) dedicated to fuels containing ethanol. In areas of the

country (e.g., the Midwest) where ethanol has been the predominant fuel additive, this will not be a

problem. However, areas of the country that have not traditionally used ethanol fuels, but would likely

do so for a part of their supply in the future, will need to make infrastructure investments to avoid losses

in air quality as a result of commingling. Even then, some commingling of fuels will likely occur when

consumers mix ethanol blended gasoline with non-ethanol blended gasoline in their vehicles’ tanks (see

discussion in Air Quality Section B.).
134 This figure is the result of the following calculations: (1) Calculate the total ether supply for RFG and

oxygenated fuels in 1997: 265,000 b/d + 17,000 b/d = 282,000 b/d; (2) Multiply 282,000 b/d by 0.52 to adjust for

the oxygen equivalency of ethanol = 146,640 b/d, or 2.2 billion gallons annually; (3) Multiply by the $0.54 per

gallon subsidy = $1.2 billion per year (refer to Table D1 in the Appendix for total ether volumes).

135 State of Nebraska Ethanol Board, “Economic Impacts of Ethanol Production in the United States,” April,

1998.

69

IV. Cost Impacts of Changing Fuel Reformulations

A. Cost Impacts

The cost of gasoline is influenced by a wide range of factors, including crude oil prices, refining costs,

the grade and type of the gasoline, taxes, available supplies (inventory), seasonal and regional market

demand, weather, transportation costs, and specific areas’ relative costs of living. Each additional cent

per gallon increase in average gasoline price is equivalent to annual costs of between $1 billion to $1.3

billion, borne ultimately by consumers.

Both ethanol and oil receive some subsidy from the government. All fuel ethanol receives a $0.54 per

gallon subsidy, while approximately 6-7 percent of gasoline receives a cost benefit from the crude oil

depletion allowance. In both cases these government subsidies are supported by Congress because it is

seen to expand domestic industry; increase commerce and employment; improve the nation’s balance of

trade (i.e., reduce imports and increase exports); and generate additional personal and corporate incomes

and the taxes accruing from these incomes. Analysis has suggested that the real cost to the government is

a net benefit. For example, replacing the 282,000 b/d of ethers used in RFG in 1997 would require

approximately 146,000 b/d of ethanol on an oxygen equivalent basis. The U.S. Environmental Protection

Agency estimates that the incremental annual cost to the Federal government (i.e., to taxpayers) for new

fuel ethanol production of 146,000 b/d (approximately 2.2 billion gallons per year) would be

approximately $1.2 billion.134 The State of Nebraska Ethanol Board estimates that the ethanol subsidy

resulted in $3.5 billion in net savings for the Federal government in 1997.135

Table 2 shows recent information from the U.S. Energy Information Administration (EIA) regarding the

price differences among CaRFG, Federal RFG, conventional gasoline, and the national average price for

gasoline. These prices reflect the various factors that influence the cost of gasoline. For example, after

reaching their lowest point in 25 years (adjusted for inflation) at the end of 1998, world crude oil prices

began recovering during the spring of 1999. In addition, April represents the beginning of the summer

driving season, which leads to higher gasoline demand; California is regionally influenced by the summer

driving demand before much of the rest of the nation. Finally, California prices have been influenced in

1999 by fires and shutdowns at several major refineries. Thus, due to regional and seasonal demand

variation, the volatility of world crude oil prices and unforeseen supply shortages, consumers may see

swings in gasoline prices of as much as $.50 per gallon.
70

Table 2. Gasoline Prices, February 1999 and April 1999

(per gallon, including State and Federal taxes)

February 1999 April 1999

California RFG $1.101 $1.568

Federal RFG $0.987 $1.229

Conventional $0.901 $1.088

Average $0.927 $1.131

 Source: U.S. Energy Information Administration

Nevertheless, the real cost of gasoline, although quite variable, increases with higher refining costs,

which are associated with environmental quality restrictions and local or regional differences in gasoline

specifications. Fuel refiners/marketers have commented that with (1) adequate lead time to make

refinery investments and modifications; (2) regulatory certainty regarding specific fuel requirements; and

(3) fuel fungibility on a regional or national scope, increases in fuel prices due to regulatory changes may

not cause substantial and unnecessary volatility in prices beyond the normal seasonal fluctuations.

Economic impacts will not be shared equally among petroleum refiners/marketers. Refineries each

process different types of crude, supply different mixes of products (e.g., some refineries do not

manufacture any RFG), and use widely varying technologies. For example, the State of California

currently requires low levels of sulfur in CaRFG. As such, the economic impact of lowering sulfur levels

would not be as great for some California refineries that manufacture mostly CaRFG as it might be for

some other refiners, and in other markets where refineries would require capital investments for

desulfurization facilities. Similarly, areas of the country that rely heavily on oxygenates such as MTBE

will experience a more pronounced economic effect in the event of a oxygenate replacement or removal

(e.g., Texas, California, and Northeast RFG markets use MTBE, whereas the Chicago and Milwaukee

RFG markets use ethanol). 

B. Modeling

Modeling fuel price increases is a relatively effective technique with which to examine the direction of

the impacts of regional fuel formulation choices on gasoline costs. Such predictions are instructive in

assessing the relative impacts of different options assuming constant assumptions. Models should not be

used, however, to predict exact outcomes. With the exception of precipitous transition times and a major

increase in ethanol use, which would require significant new infrastructure, all other modeled scenarios

add cost to gasoline of a magnitude similar to the typical variability of gasoline prices. The results of

three such models are summarized below (also refer to Table D2 in the Appendix): 

& The California Energy Commission estimated that the intermediate-term (three years)

change in the price of California RFG could range from a decrease of 0.2 cents per

gallon to an increase of 8.8 cents per gallon depending on the type of oxygenate used (if

oxygenates are used at all), the lead time to implement the changes, and flexibility
136 California Energy Commission, Supply and Cost Alternatives to MTBE in Gasoline, October 1998.

137 MathPro, Potential Economic Benefits of the Feinstein-Bilbray Bill, March 18, 1999.

138 PACE Consultants, Inc., Analysis and Refinery Implications of Ethanol-Based RFG Blends Under the

Complex Model Phase II, November 1998.

139 U.S. Department of Energy, Estimating the Refining Impacts of Revised Oxygenate Requirements for

Gasoline: Follow-up Findings, May 1999.

71

regarding the type and amount of oxygenate allowed.136 This study did not analyze the

likely economic impacts to areas outside of California if MTBE use were to be phased

out in California or nationally (i.e., increased market volatility from dependence on

imported blendstocks to replace MTBE, with or without ethanol use).

& A Chevron/Tosco analysis estimates that if refiners were given flexibility in oxygenate

use, a California ban on MTBE would increase the cost of CaRFG 2.7 cents per gallon

within a three year-period. Without oxygenate flexibility, the price would increase 6.1

cents per gallon.137

& An analysis by Pace Consultants found that it would cost an additional 0.7 to 24 cents

per gallon to make reformulated gasoline blendstock that is suitable for use with ethanol

(rather than MTBE) in the summer during the RFG Phase II program. For refiners

already using ethanol in RFG (less than 10 percent of the RFG market), the Pace study

indicated that the additional cost of using ethanol in Phase II RFG would be less than one

cent per gallon. In general, the cost of RVP reduction differs among refiners and

depends on refinery process configuration, product and raw material slates, and ability to

dispose of streams displaced in RVP reduction.138

& A recent DOE analysis shows that under the scenario of an ether ban, assuming at least

four years for refinery investment, and with a continuation of the oxygenate requirement

for RFG, the increased cost for RFG per gallon in PADD I ranges from 2.4 cents to 3.9

cents, with the cost most sensitive to the price of ethanol.139 This analysis, however, was

not national in scope.

C. Conclusions

Assuming that changes in oxygenate requirements occur, the limited modeling analyses to date have

shown that for California and PADD I: 

& Once regulations are finalized, a range of three to six years is necessary to develop the

infrastructure necessary to substantially alter the regional, possibly national, fuel

formulation and supply infrastructure without serious market volatility. 

& The estimated costs of implementing these changes will range from a slight savings

under a scenario of oxygenate-use flexibility and continued MTBE use, to a cost of about

8.8 cents per gallon under a scenario of no oxygenate use (no mandate). (See Table D2 in

the Appendix).
72

& Because no studies have been national in scope, the predictions of cost impacts are

uncertain. In addition, most studies were conducted on the assumption of meeting only

the current regulatory minimum emission reductions.

& The likely oxygenate replacement for MTBE is ethanol. Current and near future ethanol

production (i.e., on-line in less than two years), however, is not adequate to meet the

volume of oxygenate required nationally. Transporting ethanol from the Midwest, where

it is primarily produced, to Northeast and California markets will require significant

efforts to upgrade and build new pipeline (or use segregated shipments through existing

pipelines), rail, marine, and truck transportation infrastructure.
73

Appendix D

Table D1. Oxygenate Demand in Reformulated and Oxygenated Gasoline Control

Areas, 1997 

 (thousands of barrels per day)

Region Estimated 1997

Gasoline Demand in

Control Areas

Estimated Oxygenate Volume

 in Control Area Gasoline

MTBE ETBE or TAME Ethanol

Reformulated Gasoline

PADD 1 (East Coast) 1,054 128.2 9.1 1.0

PADD 2 (Midwest) 270 4.0 0.0 21.8

PADD 3 (Gulf Coast) 282 27.4 3.2 0.0

PADD 4 (Rocky Mountain) 0 0.0 0.0 0.0

PADD 5 (West Coast) 934 100.9 3.4 2.0

Subtotal 2,674 259.5 15.7 24.7

Oxygenated Gasoline

PADD 1 (East Coast) 0 0.0 0.0 0.0

PADD 2 (Midwest) 79 0.0 0.0 6.7

PADD 3 (Gulf Coast) 16 0.0 0.0 1.4

PADD 4 (Rocky Mountain) 36 0.3 1.1 2.7

PADD 5 (West Coast) 73 0.1 0.0 4.7

Subtotal 204 0.5 1.1 15.5

Oxygenated-Reformulated Gasoline

PADD 1 (East Coast) 137 4.8 0.0 0.4

PADD 5 (West Coast) 10 0.1 0.0 0.7

Subtotal 147 4.9 0.0 1.1

Average 1997 Oxygenate Demand for RFG and

Oxygenated Gasoline Blending 265 17 41

Imputed Oxygenate Demand for Conventional Gasoline

(e.g., octane and gasohol) 4a – 41

Total 1997 Oxygenate Supply 269 17 82

a

Other sources have estimated this number to be as high as 25,000 b/d (Sunoco) and 28,000 b/d (DeWitt) for ethers in the

conventional pool, with a slightly lower volume in the RFG pool.

Source: U.S. Energy Information Administration, (T. Litterdale and A. Bohn), Demand and Price Outlook for Phase 2

Reformulated Gasoline, 2000. April 1999, pp. 7-8.

Note: “–“ signifies “Not Applicable.”
74

Table D2. Summary of Modeling Results

 (cents per gallon)

Results (cents per gallon) 

Report Scenario Intermediate Term 

(3 years)

Long Term

(6 Years)

CEC Analysis:

California Only

& MTBE allowed - no

oxygenate requirement

& No oxygenates allowed -

no oxygen requirement

& Ethanol only - oxygen

requirement maintained

-0.2 to -0.8

4.3 to 8.8 

6.1 to 6.7 

-0.3 to -1.5

0.9 to 3.7

1.9 to 2.5 

Chevron/Tosco

Analysis: California

Only

& No ethers - no oxygen

requirement

& Ethanol only - oxygen

requirement maintained

2.7

6.1

1.2

1.9

Near Term 

(less than 2 years, no

investment)

Long Term 

(at least 4 years,

investment allowed)

DOE Analysis:

PADD I Only

& MTBE allowed - no

oxygenate requirement

& No ethers - no oxygen

requirement

& Ethanol only - oxygen

requirement maintained

-0.3

Not Investigated

6.0

Not Investigated

1.9

2.4 to 3.9

 Source: U.S. Environmental Protection Agency
1

 Refer to Issue Summaries A and B, “Water Contamination” and “Air Quality Benefits” respectively, for

detailed discussions of these topics.

2

 U.S. Environmental Protection Agency, Federal Register Vol. 63, No. 236, December 9, 1998, p. 67877. 

Final Notification of Health Effects Testing Requirements for Baseline Gasoline and Oxygenated Nonbaseline

Gasoline and Approval of an Alternative Emissions Generator.

3

 Jim Prah of the U.S. Environmental Protection Agency is currently conducting studies on pharmacokinetics

of MTBE.

4

 Refer to Table E1 in this section’s Appendix for detailed data on the chemical properties of these and related

compounds.

75

E. Comparing the Fuel Additives

I. Introduction

In comparing various alternatives to the current use of automotive fuel additives (primarily oxygenates),

the relative impact of these alternative compounds on the environment as a whole must be considered. 

More specifically, one must assess how changes to fuels or fuel additives impact:1

• Air quality and fuel blending characteristics;

• Fuel or fuel additive behavior and fate under various water and soil conditions;

and

• Potential health effects resulting from exposure to the additives or their

combustion products.

Health effects research is currently underway by industry2

 and EPA3 to understand more fully the

comparative risks associated with exposure to fuels both with and without oxygenates, including methyl

tertiary butyl ether (MTBE), ethanol, ethyl tertiary butyl ether (ETBE), tertiary-amyl methyl ether

(TAME), and tertiary butyl alcohol (TBA).4

 Although the majority of this research is focused on

inhalation-related health effects, the results should help in our understanding of the human health risks

associated with exposure to fuels from any route of exposure. Currently, there is not enough information

to fully characterize potential health risks of all the oxygenates or their alternatives. 

II. MTBE

A. Air Quality and Fuel 

Blending serves as a cost-effective oxygenate for blending in reformulated gasoline (RFG), enabling

fuels to meet both California and Federal RFG air quality requirements while preserving octane

enhancement, low VOC emissions, and driveability. Analyses have shown that even without an oxygen
5

 U.S. Department of Energy, Estimating the Refining Impacts of Revised Oxygenate Requirements for

Gasoline: Summary Findings, March 1999; California Energy Commission, Supply and Cost Alternatives to MTBE

in Gasoline, October 1999; Robert Cunningham, “Costs of Potential Ban of MTBE in Gasolines,” presentation at

the March 1999 MTBE Blue Ribbon Panel meeting.

6

 T.W. Kirchstetter, et. al., “Impact of Oxygenated Gasoline Use on California Light-Duty Vehicle

Emissions,” Environ. Sci. And Tech., 1996.

7

 U.S. Environmental Protection Agency, Office of Research and Development, Oxygenates in Water: Critical

Information and Research Needs, December 1998.

8

 A.M. Happel et al., An Evaluation of MTBE Impacts to California Groundwater Resources, Lawrence

Livermore National Laboratory Report, UCRL-AR-130897, June 1998. 

9

 Office of Science and Technology Policy, National Science and Technology Council. Interagency

Assessment of Oxygenated Fuels, June 1997; Steffan, R.J,. et. al., Biodegradation of the Gasoline Oxygenates

Methyl tert-Butyl Ether (MTBE), Ethyl tert-Butyl Ether (ETBE), and tert-Amyl Methyl Ether (TAME) by Propane

Oxidizing Bacteria, Appl. Environ. Microbiol. 63(11):4216-4222).

76

mandate, MTBE use is economically suited to meet air quality and gasoline performance goals.5

However, it should be noted that emissions of formaldehyde (a probable carcinogen), resulting from the

incomplete combustion of fuels, increase by about 13 (+ 6) percent with the use of 2.0 percent by weight

(wt%) MTBE oxygenated gasoline.6

B. Behavior in Water

MTBE, an ether, is more soluble in water than other gasoline components and appears recalcitrant to

biodegradation relative to other components of concern in gasoline, such as benzene, toluene,

ethylbenzene, and xylenes (collectively referred to as “BTEX”).7

 In general, compared to the slow

migration of BTEX compounds in subsurface soil and ground water, MTBE moves at nearly the same

velocity as the ground water itself. This is due to MTBE’s high water solubility and low soil sorption. 

Given sufficient time and distance, MTBE would be expected to be at the leading edge of a gasoline

contamination plume or could become completely separated from the rest of the plume if the original

source of oxygenate were eliminated.8

Tert-butyl alcohol (TBA) is the primary metabolite of MTBE resulting from biodegradation, but is also a

common byproduct in the production of MTBE and often present with MTBE in the fuel supply. Thus,

detection of TBA in ground water is not necessarily evidence of MTBE biodegradation. By itself, TBA,

like ethanol, is infinitely (miscible) soluble in water and is reported to be recalcitrant to biodegradation.9

C. Health Effects

In terms of neurotoxicity and reproductive effects, inhalation toxicity testing to date generally has not

shown MTBE to be any more toxic than other components of gasoline. At high doses, MTBE has caused

tumors in two species of rat and one species of mouse at a variety of sites; it is uncertain, however,

whether these effects can be extrapolated to humans. The International Agency for Research on Cancer
10 Office of Science and Technology Policy, National Science and Technology Council, Interagency

Assessment of Oxygenated Fuels, June 1997.

11 Office of Science and Technology Policy, National Science and Technology Council, Interagency

Assessment of Oxygenated Fuels, June 1997.

12 Correspondence with the Health Effects Institute, Chemical Industry Institute of Toxicology, and EPA verify

currently on-going studies on animal and human health effects from MTBE exposure.

13 U.S. Environmental Protection Agency, Office of Water, Drinking Water Advisory: Consumer

Acceptability Advice and Health Effects Analysis on Methyl Tertiary-Butyl Ether (MTBE), December 1997.

14 It should be noted that the National Research Council has cautioned against the use of this study until a

thorough review has been accomplished, including an objective third-party review of the pathology. (Toxicological

and Performance Aspects of Oxygenated Motor Vehicle Fuels, National Research Council, Washington, D.C. 1996,

page 115.)

15 U.S. Environmental Protection Agency, Office of Water, Drinking Water Advisory: Consumer

Acceptability Advice and Health Effects Analysis on Methyl Tertiary-Butyl Ether (MTBE), December 1997.

16 U.S. Environmental Protection Agency, Office of Water, Drinking Water Advisory: Consumer

Acceptability Advice and Health Effects Analysis on Methyl Tertiary-Butyl Ether (MTBE), December 1997.

77

(IARC) and the National Institute of Environmental Health Sciences (NIEHS) have indicated that at this

time there are not adequate data to consider MTBE a probable or known human carcinogen.10

There are limited data on human populations that may be sensitive to MTBE. Although there is some

evidence that fuels containing MTBE could irritate the eyes, as well as cause headaches and rashes,

effects attributed to MTBE alone have yet to be proven. Limited epidemiological data suggest greater

attention should be given to the potential for increased symptom reporting among highly exposed

workers.11

There have been no human or animal health effects studies performed for MTBE in drinking water. 

However, human and animal studies are currently underway at the U.S. Environmental Protection

Agency (EPA), Health Effects Institute (HEI) and the Chemical Industry Institute of Toxicology (CIIT)

to address some of these research needs.12 Animal ingestion studies using “bolus” (all at once) dosing of

MTBE in olive oil have shown carcinogenic effects at high levels of exposure (250,000 micrograms per

kilogram animal body weight and higher).13 14

Drinking water containing MTBE at or below the taste and odor levels identified in the EPA’s Drinking

Water Advisory (20 to 40 micrograms per liter) is not expected to cause adverse health concerns for the

majority of the population.15 The turpentine-like taste and odor of MTBE, however, can make such

drinking water unacceptable to consumers.

TBA is a major metabolite of MTBE, regardless of the route of exposure. Animal testing of TBA in

drinking water produced carcinogenic effects at high levels of exposure (1,250,000 micrograms per liter

and higher).16 Additionally, formaldehyde, also a metabolite of MTBE, is a respiratory irritant at high
17 Office of Science and Technology Policy, National Science and Technology Council, Interagency

Assessment of Oxygenated Fuels, June 1997.

18 Refer to Issue Summary D, “Fuel Supply and Cost,” for a more detailed discussion of this topic.

19 California Energy Commission, Supply and Cost Alternatives to MTBE in Gasoline, October 1999.

20 Office of Science and Technology Policy, National Science and Technology Council, Interagency

Assessment of Oxygenated Fuels, June 1997.

21 Office of Science and Technology Policy, National Science and Technology Council, Interagency

Assessment of Oxygenated Fuels, June 1997.

22 J. Froines et. al., Health and Environmental Assessment of MTBE, Vol. II, November, 1998; A.P. Altshuller,

“PANs in the Atmosphere,” J. Air Waste Manag. Assoc., 1993, 43(9), 1221-1230; L. Milgrom, “Clean Car Fuels

Run Into Trouble,” New Scientist, 1989, 122 (1656), 30.

78

levels of human exposure and is currently considered by EPA to be a probable human carcinogen by the

inhalation route, with less certainty via ingestion.17

III. Ethanol

A. Air Quality and Fuel Blending

Ethanol is commonly used as an octane enhancer in conventional gasoline, as well as serving as an

oxygenate for blending in Federal RFG and oxygenated gasoline in a number of locations (primarily in

the Midwest).18 Because of its unique physical and chemical properties, ethanol raises the volatility of

gasoline with which it is blended, thus additional refinery processing of blendstocks is performed prior to

ethanol blending in order to meet the air quality performance standards in reformulated fuels.19 Ethanol

is soluble in the water commonly found in pipelines and storage tanks associated with the gasoline

distribution system, and once mixed with water will separate from the gasoline. Due to this potential

phase separation, which can occur when ethanol and gasoline blends are transported through pipelines,

ethanol is usually blended at the terminal, rather than the refinery.

A National Research Council study20 did not support using ozone forming potential or reactivity (as

opposed to mass emission reductions) to assess the relative effectiveness of MTBE or ethanol in the RFG

program. However, the report did find that the contribution of the reduction of carbon monoxide (CO)

and its effect on ozone formation should be recognized in assessments of the effects of ethanol in RFG.

(Refer to Issue Summary B, “Air Quality Benefits.”)

In markets where ethanol blended fuels make up 30 percent to 50 percent of the market, the possibility of

commingling of ethanol fuels with non-ethanol fuels in the fuel supply system will require separation of

ethanol fuel infrastructure, and commingling in the gas tank can result in an increase in both vapor

pressure and evaporative emissions.21 (Refer to Issue Summary B, “Air Quality Benefits.”)

Vehicle exhaust emissions data have shown that acetaldehyde (principle metabolite of ethanol) emissions

can increase by as much as 100 percent with the use of 2.0 wt% ethanol oxygenated gasoline, part of

which undergoes photochemical reactions in the atmosphere to make peroxyacetyl nitrate (PAN).22
23 Michael Kavanaugh and Andrew Stocking, “Fate and Transport of Ethanol in the Environment,”

presentation at the May 1999 MTBE Blue Ribbon Panel meeting. [Based on Malcome Pirnie, Inc. Evaluation of

the Fate and Transport of Ethanol in the Environment (Oakland, CA, 1998.)]

24 Michael Kavanaugh and Andrew Stocking, “Fate and Transport of Ethanol in the Environment,”

presentation at the May 1999 MTBE Blue Ribbon Panel meeting. [Based on Malcome Pirnie, Inc. Evaluation of

the Fate and Transport of Ethanol in the Environment (Oakland, CA, 1998.)]

25 Health Effects Institute, The Potential Health Effects of Oxygenates Added to Gasoline, April 1996.

26 Health Effects Institute, The Potential Health Effects of Oxygenates Added to Gasoline, April 1996.

27 L. Milgrom, “Clean Car Fuels Run Into Trouble,” New Scientist, 1989, 122 (1656), 30.

79

B. Behavior in Water

“Neat” (pure) ethanol is infinitely soluble in water. Laboratory data and hypothetical modeling indicate

that based on physical, chemical, and biological properties, ethanol will likely preferentially biodegrade

in ground water compared with other gasoline components with the potential to extend BTEX plumes

further than they would be without ethanol present.23

Although ethanol has been shown to retard BTEX biodegradation under certain laboratory conditions,

evidence of ethanol’s effect on the migration of BTEX plumes under various conditions, i.e.,

hydrogeology; field concentrations; nature of release scenario (for example, large sudden release versus

slow continuous release) has not been collected and compiled.24 A more comprehensive review is still

needed to investigate and determine the nature and extent of field experiences regarding ethanol’s effect

(including behavior and fate properties) on BTEX plume migration, aquifer remediation, and drinking

water treatment.

C. Health Effects

The health effects of ingested ethanol have been extensively investigated. Given that ethanol is formed

naturally in the body at low levels, inhalation exposure to ethanol at the low levels that humans are likely

to be exposed are generally not expected to result in adverse health effects.25 Health effects questions

have been raised, however, about potentially sensitive subpopulations. In addition, increased use of

ethanol may result in increases of certain atmospheric transformation products, such as PAN and

acetaldehyde, although the extent of such increase is unknown.26 PAN, which has been shown to be

mutagenic in cellular research, is a known toxin to plant life and a respiratory irritant to humans.27

Combustion byproducts of ethanol may also cause adverse health effects. Acetaldehyde is a respiratory

irritant at high levels of human exposure and is currently classified by EPA as a probable human

carcinogen. 
28 Ethers are organic compounds consisting of carbon, hydrogen, and oxygen. Often used as gasoline

blendstocks and as oxygenates, ethers include: MTBE; ETBE; TAME; and diisopropyl ether (DIPE).

29 Dexter Miller, “Alkylates, Key Components in Clean-Burning Gasoline,” presentation at the May 1999

MTBE Blue Ribbon Panel meeting. 

30 Duane Bordvick, Tosco Corporation, “Perspectives on Gasoline Blending for Clean Air,” presentation at the

March 1999 MTBE Blue Ribbon Panel meeting; Al Jessel, Chevron Products Company, “Removing MTBE From

Gasoline,” presentation at the March 1999 MTBE Blue Ribbon Panel meeting.

80

IV. Other Ethers28

A. Air Quality and Fuel Blending

Other ethers have been shown to provide the same emissions benefits as MTBE or ethanol. Alternative

ethers (except tertiary-amyl methyl ether - TAME) have found only limited use, however, because they

are economically less competitive to manufacture.

B. Behavior in Water

Other ethers are likely to be similar, although not identical to, MTBE, i.e. highly soluble in ground water,

poorly sorbed to soil, and degraded more slowly than BTEX chemicals. Behavior in ground water is a

function of solubility, soil sorption, and the ability to biodegrade. All oxygenates are significantly more

soluble than benzene and evidence to date demonstrates that in situ biodegradation of these compounds is

limited as compared to benzene. Differences may exist between solubility and degradability of ethers. 

Accelerated studies are necessary in order to make this determination. 

C. Health Effects

Although toxicity testing of these substances is underway, there is less current knowledge regarding the

inhalation or ingestion health effects associated with these compounds than for ethanol and MTBE. 

V. Other Alternatives 

A. Air Quality and Fuel Blending

In addition to ethanol, the most likely alternatives to replace the current volume of MTBE and other

ethers in RFG are increased use of refinery streams such as alkylates, reformates, aromatics, and other

streams resulting from the fluid catalytic cracking (FCC) processes.

Alkylates are a mix of high octane, low vapor pressure branched chain paraffinic hydrocarbons that can

be made from crude oil through well established refinery processes, using the output from an FCC unit. 

Because of these desirable properties, alkylates are highly favored as streams for blending into gasoline.29

In general, an increase in the amount of alkylates used in fuels will have no adverse effect on overall

vehicle performance.30 Aromatics are hydrocarbons characterized by unsaturated ring structures of

carbon atoms (i.e. benzene, toluene, and xylene), and increased use of aromatics would be likely to
31 MathPro, Potential Economic Benefits of the Feinstein-Bilbray Bill, March 18, 1999.

81

increase toxic emissions when used in high quantities. Refiners in California have produced nonoxygenated fuels using lower sulfur, alkylates and aromatics, that meet or exceed all California RFG air

quality requirements.31

B. Behavior in Water

Alkylates are nonpolar and have a much lower (over 100 times less) solubility in water than aromatics

such as BTEX compounds. Based on alkylates’ physical, chemical, and biological properties, dissolution

from the gasoline source area, biodegradation, and movement in ground water, are all expected to be

significantly slower than BTEX compounds.

Water-related environmental fate research should include studies in the following areas: 

& Water solubility, dissolution behavior, and sorption tendency to soil and aquifer material;

& Effects of biodegradation on the gasoline contaminated plume’s overall movement;

• Transformation studies to determine if the compound breaks down in soil or

surface/ground water; and 

• Whether intermediates and/or final products pose either a greater or lesser risk.

C. Health Effects

Alkylates have long been a common ingredient in fuels, and thus a modest increase in alkylate content

would not be expected to cause additional human health risks above those already associated with human

exposure to fuels. However, the human and aquatic toxicity risk data associated with exposure to

alkylates are limited. Aromatics have also long been used in fuel, and contain compounds (e.g. benzene

and toluene) which are known to have a range of potential health effects; any substantial increase in their

use should be carefully evaluated. At a minimum, testing for non oxygenated fuel alternatives should

include sufficient data to develop an adequate risk assessment. These tests should seek inhalation and

ingestion data through animal toxicity and human microenvironmental exposure studies using both the

additives themselves, and the gasoline mixtures of which they are a part.
82

Appendix E

Table E1. Chemical Properties of Selected Compoundsa

Benzene2 MTBE2 Ethanol3 ETBE1 TAME1 TBA3

Alkylates

(isooctane)

Molecular Weight (g/mol) 78.11 88.2 46.1 102.2 102.2 74.1 114.2

Boiling Point (0 C) 80.1 55.2 78.5 72.2 86.3 82.4 99.2

Vapor Pressure

(mm Hg at 20 0 C) 73 240 44 130 75 41 72

Density (g/L) 0.88 0.74 0.79 0.74 0.77 0.79 0.69

Octane Number 94 110 115 112 105 100 100

Neat Solubility (g/100g H20) 0.178 4.8 miscible 1.2 1.2

miscibl

e << 0.01

Solubility into H20 from

Gasoline (g/100g H20) <.01 0.55 5.7b 0.33 0.24 2.5b –

Taste Threshold

in Water (ug/L) 500 20 to 40 – 47 128 – –

Odor Threshold (ppm) 0.5 0.053 49 0.013 0.027 21 –

 a Adapted from USGS. For a detailed discussion of the solubility in water from gasoline mixture containing 2% oxygen, see p.

2-50 - 2-53 of the National Science and Technology Council. Interagency Assessment of Oxygenated Fuels (June 1997).

b

 The water solubilities of the alcohols are estimates based on partitioning properties.

Sources:

1

 D.L. Conrad, Texaco Research and Development Department, The Impacts of Gasoline Oxygenate Releases to the

Environment -- A Review of the Literature (Port Arthur, Texas, 1995).

2

 Donald Mackay, W.Y. Shiu, and K.C. Ma, Illustrated Handbook of Physical-Chemical Properties and Environmental Fate for

Organic Chemicals: Vol. III, Volatile Organic Compounds (Boca Raton, FL: Lewis Publishers, Inc, 1993) p. 916.

3

 Donald Mackay, W.Y. Shiu, and K.C. Ma, Illustrated Handbook of Physical-Chemical Properties and Environmental Fate for

Organic Chemicals: Vol. III, Volatile Organic Compounds (Boca Raton, FL: Lewis Publishers, Inc, 1993) p. 962. 

Key:

 “ – “ signifies “Not Applicable.” 

g/mol = Grams Per Mole

x0C = Degrees Celsius

mm Hg = Millimeters of Mercury

g/L = Grams Per Liter

g/100g H20 - Grams Per 100 Grams of Water

ug/L = Micrograms Per Liter

ppm = Parts Per Million
83

CHAPTER 3. FINDINGS AND RECOMMENDATIONS OF THE

BLUE RIBBON PANEL

Findings

Based on its review of the issues, the Panel made the following overall findings:

& The distribution, use, and combustion of gasoline poses risks to our environment and

public health. 

& RFG provides considerable air quality improvements and benefits for millions of US

citizens.

& The use of MTBE has raised the issue of the effects of both MTBE alone and MTBE in

gasoline. This Panel was not constituted to perform an independent comprehensive

health assessment and has chosen to rely on recent reports by a number of state, national,

and international health agencies. What seems clear, however, is that MTBE, due to its

persistence and mobility in water, is more likely to contaminate ground and surface water

than the other components of gasoline.

& MTBE has been found in a number of water supplies nationwide, primarily causing

consumer odor and taste concerns that have led water suppliers to reduce use of those

supplies. Incidents of MTBE in drinking water supplies at levels well above EPA and

state guidelines and standards have occurred, but are rare. The Panel believes that the

occurrence of MTBE in drinking water supplies can and should be substantially reduced.

& MTBE is currently an integral component of the U.S. gasoline supply both in terms of

volume and octane. As such, changes in its use, with the attendant capital construction

and infrastructure modifications, must be implemented with sufficient time, certainty,

and flexibility to maintain the stability of both the complex U. S. fuel supply system and

gasoline prices. 

The following recommendations are intended to be implemented as a single package of actions designed

to simultaneously maintain air quality benefits while enhancing water quality protection and assuring a

stable fuel supply at reasonable cost. The majority of these recommendations could be implemented by

federal and state environmental agencies without further legislative action, and we would urge their rapid

implementation. We would, as well, urge all parties to work with Congress to implement those of our

recommendations that require legislative action.

Recommendations to Enhance Water Protection

Based on its review of the existing federal, state and local programs to protect, treat, and remediate water

supplies, the Blue Ribbon Panel makes the following recommendations to enhance, accelerate, and

expand existing programs to improve protection of drinking water supplies from contamination. 
84

Prevention

1. EPA, working with the states, should take the following actions to enhance significantly

the Federal and State Underground Storage Tank programs:

a. Accelerate enforcement of the replacement of existing tank systems to conform

with the federally-required December 22, 1998 deadline for upgrade, including,

at a minimum, moving to have all states prohibit fuel deliveries to non-upgraded

tanks, and adding enforcement and compliance resources to ensure prompt

enforcement action, especially in areas using RFG and Wintertime Oxyfuel.

b. Evaluate the field performance of current system design requirements and

technology and, based on that evaluation, improve system requirements to

minimize leaks/releases, particularly in vulnerable areas (see recommendations

on Wellhead Protection Program in 2. below).

c. Strengthen release detection requirements to enhance early detection,

particularly in vulnerable areas, and to ensure rapid repair and remediation.

d. Require monitoring and reporting of MTBE and other ethers in groundwater at

all UST release sites.

e. Encourage states to require that the proximity to drinking water supplies, and the

potential to impact those supplies, be considered in land-use planning and

permitting decisions for siting of new UST facilities and petroleum pipelines.

f. Implement and/or expand programs to train and license UST system installers

and maintenance personnel.

g. Work with Congress to examine and, if needed, expand the universe of regulated

tanks to include underground and aboveground fuel storage systems that are not

currently regulated yet pose substantial risk to drinking water supplies.

2. EPA should work with its state and local water supply partners to enhance

implementation of the Federal and State Safe Drinking Water Act programs to:

a. Accelerate, particularly in those areas where RFG or Oxygenated Fuel is used,

the assessments of drinking water source protection areas required in Section

1453 of the Safe Drinking Water Act, as amended in 1996.

b. Coordinate the Source Water Assessment program in each state with federal and

state Underground Storage Tank Programs using geographic information and

other advanced data systems to determine the location of drinking water sources

and to identify UST sites within source protection zones.
85

c. Accelerate currently-planned implementation of testing for and reporting of

MTBE in public drinking water supplies to occur before 2001.

d. Increase ongoing federal, state, and local efforts in Wellhead Protection Areas

including:

6 enhanced permitting, design, and system installation requirements for

USTs and pipelines in these areas;

6 strengthened efforts to ensure that non-operating USTs are properly

closed;

6 enhanced UST release prevention and detection; and

6 improved inventory management of fuels.

3. EPA should work with states and localities to enhance their efforts to protect lakes and

reservoirs that serve as drinking water supplies by restricting use of recreational water

craft, particularly those with older motors.

4. EPA should work with other federal agencies, the states, and private sector partners to

implement expanded programs to protect private well users, including, but not limited to:

a. A nationwide assessment of the incidence of contamination of private wells by

components of gasoline as well as by other common contaminants in shallow

groundwater;

b. Broad-based outreach and public education programs for owners and users of

private wells on preventing, detecting, and treating contamination; and

c. Programs to encourage and facilitate regular water quality testing of private

wells.

5. Implement, through public-private partnerships, expanded Public Education programs at

the federal, state, and local levels on the proper handling and disposal of gasoline.

6. Develop and implement an integrated field research program into the groundwater

behavior of gasoline and oxygenates, including:

a. Identifying and initiating research at a population of UST release sites and

nearby drinking water supplies including sites with MTBE, sites with ethanol,

and sites using no oxygenate; and

b. Conducting broader, comparative studies of levels of MTBE, ethanol, benzene,

and other gasoline compounds in drinking water supplies in areas using primarily

MTBE, areas using primarily ethanol, and areas using no or lower levels of

oxygenate.
86

Treatment and Remediation

7. EPA should work with Congress to expand resources available for the up-front funding

of the treatment of drinking water supplies contaminated with MTBE and other gasoline

components to ensure that affected supplies can be rapidly treated and returned to

service, or that an alternative water supply can be provided. This could take a number of

forms, including but not limited to:

a. Enhancing the existing Federal Leaking Underground Storage Tank Trust Fund

by fully appropriating the annual available amount in the Fund, ensuring that

treatment of contaminated drinking water supplies can be funded, and

streamlining the procedures for obtaining funding;

b. Establishing another form of funding mechanism which ties the funding more

directly to the source of contamination; and

c. Encouraging states to consider targeting State Revolving Funds (SRF) to help

accelerate treatment and remediation in high priority areas.

8. Given the different behavior of MTBE in groundwater when compared to other

components of gasoline, states in RFG and Oxyfuel areas should reexamine and enhance

state and federal “triage” procedures for prioritizing remediation efforts at UST sites

based on their proximity to drinking water supplies.

9. Accelerate laboratory and field research, and pilot projects, for the development and

implementation of cost-effective water supply treatment and remediation technology, and

harmonize these efforts with other public/private efforts underway.

Recommendations for Blending Fuel for Clean Air and Water

Based on its review of the current water protection programs, and the likely progress that can be made in

tightening and strengthening those programs by implementing Recommendations 1 - 9 above, the Panel

agreed broadly, although not unanimously, that even enhanced protection programs will not give

adequate assurance that water supplies will be protected, and that changes need to be made to the RFG

program to reduce the amount of MTBE being used, while ensuring that the air quality benefits of RFG,

and fuel supply and price stability, are maintained.

Given the complexity of the national fuel system, the advantages and disadvantages of each of the fuel

blending options the Panel considered (see Appendix A), and the need to maintain the air quality benefits

of the current program, the Panel recommends an integrated package of actions by both Congress and

EPA that should be implemented as quickly as possible. The key elements of that package, described in

more detail below, are:

& Action agreed to broadly by the Panel to reduce the use of MTBE substantially (with

some members supporting its complete phase-out), and action by Congress to clarify
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federal and state authority to regulate and/or eliminate the use of gasoline additives that

threaten drinking water supplies; 

& Action by Congress to remove the current 2 percent oxygen requirement to ensure that

adequate fuel supplies can be blended in a cost-effective manner while quickly reducing

usage of MTBE; and

& Action by EPA to ensure that there is no loss of current air quality benefits.

The Oxygen Requirement

10. The current Clean Air Act requirement to require 2 percent oxygen, by weight, in RFG

must be removed in order to provide flexibility to blend adequate fuel supplies in a costeffective manner while quickly reducing usage of MTBE and maintaining air quality

benefits.

The Panel recognizes that Congress, when adopting the oxygen requirement, sought to

advance several national policy goals (energy security and diversity, agricultural policy,

etc) that are beyond the scope of our expertise and deliberations. 

The Panel further recognizes that if Congress acts on the recommendation to remove the

requirement, Congress will likely seek other legislative mechanisms to fulfill these other

national policy interests.

Maintaining Air Benefits

11. Present toxic emission performance of RFG can be attributed, to some degree, to a 

combination of three primary factors: (1) mass emission performance requirements; (2)

the use of oxygenates; and (3) a necessary compliance margin with a per gallon standard. 

In Cal RFG, caps on specific components of fuel is an additional factor to which toxics

emission reductions can be attributed.

Outside of California, lifting the oxygen requirement as recommended above may lead to

fuel reformulations that achieve the minimum performance standards required under the

1990 Act, rather than the larger air quality benefits currently observed. In addition,

changes in the RFG program could have adverse consequences for conventional gasoline

as well.

Within California, lifting the oxygen requirement will result in greater flexibility to

maintain and enhance emission reductions, particularly as California pursues new

formulation requirements for gasoline. 

In order to ensure that there is no loss of current air quality benefits, EPA should seek

appropriate mechanisms for both the RFG Phase II and Conventional Gasoline programs

to define and maintain in RFG II the real world performance observed in RFG Phase I
32 The Panel is aware of the current proposal for further changes to the sulfur levels of gasoline and recognizes

that implementation of any change resulting from the Panel’s recommendations will, of necessity, need to be

coordinated with implementation of these other changes. However, a majority of the Panel considered the

maintenance of current RFG air quality benefits as separate from any additional benefits that might accrue from the

sulfur changes currently under consideration.

33 Under §211 of the 1990 Clean Air Act, Congress provided EPA with authority to regulate fuel formulation

to improve air quality. In addition to EPA’s national authority, in §211(c)(4) Congress sought to balance the desire for

maximum uniformity in our nation’s fuel supply with the obligation to empower states to adopt measures necessary to meet

national air quality standards. Under §211(c)(4), states may adopt regulations on the components of fuel, but must demonstrate

that 1) their proposed regulations are needed to address a violation of the NAAQS and 2) it is not possible to achieve the desired

outcome without such changes.

The Panel recommends that Federal law be amended to clarify EPA and state authority to regulate and/or eliminate

gasoline additives that threaten water supplies. It is expected that this would be done initially on a national level to maintain

uniformity in the fuel supply. For further action by the states, the granting of such authority should be based upon a similar two

part test:

1) states must demonstrate that their water resources are at risk from MTBE use, above and beyond the risk posed by

other gasoline components at levels of MTBE use present at the time of the request.

2) states have taken necessary measures to restrict/eliminate the presence of gasoline in the water resource. 

To maximize the uniformity with which any changes are implemented and minimize impacts on cost and

fuel supply, the Panel recommends that EPA establish criteria for state waiver requests including but not

limited to: 

a. Water quality metrics necessary to demonstrate the risk to water resources and air quality metrics

to ensure no loss of benefits from the federal RFG program.

b. Compliance with federal requirements to prevent leaking and spilling of gasoline.

c. Programs for remediation and response.

d. A consistent schedule for state demonstrations, EPA review, and any resulting regulation of the

volume of gasoline components in order to minimize disruption to the fuel supply system.

88

while preventing deterioration of the current air quality performance of conventional

gasoline.32

There are several possible mechanisms to accomplish this. One obvious way is to

enhance the mass-based performance requirements currently used in the program. At the

same time, the Panel recognizes that the different exhaust components pose differential

risks to public health due in large degree to their variable potency. The Panel urges EPA

to explore and implement mechanisms to achieve equivalent or improved public health

results that focus on reducing those compounds that pose the greatest risk.

Reducing the Use of MTBE

12. The Panel agreed broadly that, in order to minimize current and future threats to drinking

water, the use of MTBE should be reduced substantially. Several members believed that

the use of MTBE should be phased out completely. The Panel recommends that

Congress act quickly to clarify federal and state authority to regulate and/or eliminate the

use of gasoline additives that pose a threat to drinking water supplies.33
34 Although a rapid, substantial reduction will require removal of the oxygen requirement, EPA should, in

order to enable initial reductions to occur as soon as possible, review administrative flexibility under existing law to

allow refiners who desire to make reductions to begin doing so.

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Initial efforts to reduce should begin immediately, with substantial reductions to begin as

soon as Recommendation 10 above - the removal of the 2 percent oxygen requirement -

is implemented34. Accomplishing any such major change in the gasoline supply without

disruptions to fuel supply and price will require adequate lead time - up to 4 years if the

use of MTBE is eliminated, sooner in the case of a substantial reduction (e.g. returning

to historical levels of MTBE use). 

The Panel recommends, as well, that any reduction should be designed so as to not result

in an increase in MTBE use in Conventional Gasoline areas.

13. The other ethers (e.g. ETBE, TAME, and DIPE) have been less widely used and less

widely studied than MTBE. To the extent that they have been studied, they appear to

have similar, but not identical, chemical and hydrogeologic characteristics. The Panel

recommends accelerated study of the health effects and groundwater characteristics of

these compounds before they are allowed to be placed in widespread use. 

In addition, EPA and others should accelerate ongoing research efforts into the

inhalation and ingestion health effects, air emission transformation byproducts, and

environmental behavior of all oxygenates and other components likely to increase in the

absence of MTBE. This should include research on ethanol, alkylates, and aromatics, as

well as of gasoline compositions containing those components.

14. To ensure that any reduction is adequate to protect water supplies, the Panel recommends

that EPA, in conjunction with USGS, the Departments of Agriculture and Energy,

industry, and water suppliers, should move quickly to:

a. Conduct short-term modeling analyses and other research based on existing data

to estimate current and likely future threats of contamination;

b. Establish routine systems to collect and publish, at least annually, all available

monitoring data on:

6 use of MTBE, other ethers, and Ethanol; 

6 levels of MTBE, Ethanol, and petroleum hydrocarbons found in ground,

surface and drinking water;

6 trends in detections and levels of MTBE, Ethanol, and petroleum

hydrocarbons in ground and drinking water; 

c. Identify and begin to collect additional data necessary to adequately assess the

current and potential future state of contamination.

The Wintertime Oxyfuel Program
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The Wintertime Oxyfuel Program continues to provide a means for some areas of the country to

come into, or maintain, compliance with the Carbon Monoxide standard. Only a few

metropolitan areas continue to use MTBE in this program. In most areas today, ethanol can and

is meeting these wintertime needs for oxygen without raising volatility concerns given the

season.

15. The Panel recommends that the Wintertime Oxyfuel program be continued (a) for as

long as it provides a useful compliance and/or maintenance tool for the affected states

and metropolitan areas, and (b) assuming that the clarification of state and federal

authority described above is enacted to enable states, where necessary, to regulate and/or

eliminate the use of gasoline additives that threaten drinking water supplies.

Recommendations for Evaluating and Learning From Experience

The introduction of reformulated gasoline has had substantial air quality benefits, but has at the same

time raised significant issues about the questions that should be asked before widespread introduction of

a new, broadly-used product. The unanticipated effects of RFG on groundwater highlight the importance

of exploring the potential for adverse effects in all media (air, soil, and water), and on human and

ecosystem health, before widespread introduction of any new, broadly-used, product.

16. In order to prevent future such incidents, and to evaluate of the effectiveness and the

impacts of the RFG program, EPA should:

a. Conduct a full, multi-media assessment (of effects on air, soil, and water) of any

major new additive to gasoline prior to its introduction;

b. Establish routine and statistically valid methods for assessing the actual

composition of RFG and its air quality benefits, including the development, to

the maximum extent possible, of field monitoring and emissions characterization

techniques to assess “real world” effects of different blends on emissions;

c. Establish a routine process, perhaps as a part of the Annual Air Quality trends

reporting process, for reporting on the air quality results from the RFG program;

and

& Build on existing public health surveillance systems to measure the broader

impact (both beneficial and adverse) of changes in gasoline formulations on

public health and the environment.
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Appendix A

In reviewing the RFG program, the Panel identified three main options (MTBE and other ethers, ethanol,

and a combination of alkylates and aromatics) for blending to meet air quality requirements. They

identified strength and weaknesses of each option:

MTBE/other ethers A cost-effective fuel blending component that provides high octane, carbon

monoxide and exhaust VOCs emissions benefits, and appears to contribute to

reduction of the use of aromatics with related toxics and other air quality

benefits; has high solubility and low biodegradability in groundwater, leading to

increased detections in drinking water, particularly in high MTBE use areas. 

Other ethers, such as ETBE, appear to have similar, but not identical, behavior in

water, suggesting that more needs to be learned before widespread use.

Ethanol An effective fuel-blending component, made from domestic grain and potentially from

recycled biomass, that provides high octane, carbon monoxide emission benefits, and

appears to contribute to reduction of the use of aromatics with related toxics and other

air quality benefits; can be blended to maintain low fuel volatility; could raise possibility

of increased ozone precursor emissions as a result of commingling in gas tanks if ethanol

is not present in a majority of fuels; is produced currently primarily in Midwest,

requiring enhancement of infrastructure to meet broader demand; because of high

biodegradability, may retard biodegradation and increase movement of benzene and

other hydrocarbons around leaking tanks.

Blends of Alkylates Effective fuel blending components made from crude oil; alkylates

and Aromatics provide lower octane than oxygenates; increased use of aromatics will likely

result in higher air toxics emissions than current RFG; would require

enhancement of infrastructure to meet increased demand; have groundwater

characteristics similar, but not identical, to other components of gasoline (i.e.

low solubility and intermediate biodegradability).
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CHAPTER 4. DISSENTING OPINIONS

State of Nebraska, Nebraska Ethanol Board

Oxygen Standard Should Be Maintained

Insufficient Evidence to Support Recommendation to Remove Oxygen Standard

Blue Ribbon Panel Dissenting Opinion

Submitted for the Record By

Todd C. Sneller, Panel Member

In its report regarding the use of oxygenates in gasoline, a majority of the Blue Ribbon Panel on

Oxygenates in Gasoline (BRP) has based its recommendation to support removal of the oxygen standard

on several conclusions which I believe to be inaccurate: 

1). That aromatics can be used as a safe and effective replacement for oxygenates without

resulting in deterioration in VOC and air toxic emissions. In fact, a review of the legislative

history behind the passage of the Clean Air Act Amendments of 1990 clearly shows that Congress

found the increased use of aromatics to be harmful to human health and intended that their use in

gasoline be reduced as much as technically feasible.

2). That oxygenates fail to provide overwhelming air quality benefits associated with their

required use in gasoline. The BRP recommendations do not accurately reflect the benefits

provided by the use of oxygenates in reformulated gasoline. Congress correctly saw a minimum

oxygenate requirement as a cost effective means to both reduce levels of harmful aromatics and

help rid the air we breathe of harmful pollutants.

3). That the BRP recommendation to urge removal of the oxygen standard does not fully take

into account other public policy objectives specifically identified during Congressional debate on

the 1990 CAAA. While projected benefits related to public health were a focal point during the

debate in 1990, energy security, national security, the environment and economic impacts of the

Amendments were clearly part of the rationale for adopting such amendments. It is my belief that

the rationale behind adoption of the Amendments in 1990 is equally valid, if not more so, today.

As Congress debated the Reformulated Gasoline (RFG) provisions of the Clean Air Act Amendments of

1990, it became clear that aromatics (e.g. benzene, xylene, and toluene) added to gasoline were extremely

toxic, and lead to the further deterioration of U.S. air quality. To specifically reduce aromatic levels in

RFG – and help remove harmful air toxics from the air – an overwhelming bi-partisan majority of

Congress specifically required the addition of cleaner burning oxygenates to gasoline. As stated in the

record, a primary purpose behind the addition of oxygenates to gasoline was the reduction in carbon

monoxide emissions in winter, ozone formation in summer, and air toxic emissions year-round.

Recognizing the harmful effects increased aromatic use has on public health, Senate Democratic Leader

Tom Daschle (D-SD), a primary sponsor of the RFG provision, said on March 29, 1990;
93

“The primary aromatics used in gasoline are benzene, toluene and xylene, all of which

are EPA-listed hazardous chemicals. The amount of benzene emitted from the tailpipe is

directly related to the amount of benzene found in gasoline. However, a gasoline can

have no benzene and still produce benzene exhaust because of the chemical

transformation that toluene and xylene undergo during the combustion process.”...”The

most significant single step that can be taken to improve urban air quality is to limit

aromatic content in gasoline.” (Emphasis added)

Echoing that Congressional sentiment, Senator Tom Harkin (D-IA) said;

“The aromatic hydrocarbons in gasoline include benzene, toluene, and xylene. Benzene

is a known carcinogen, one of the worst air toxics. Eighty-five percent of all benzene in

the air we breathe comes from motor vehicle exhaust. Xylene, another aromatic, is

highly photoreactive – meaning that it forms ozone very rapidly in sunlight. Xylene from

automobile exhaust in the morning rush hour forms ozone in sunlight to choke our lungs

by the afternoon trip home. Toluene, another aromatic, usually forms benzene during the

combustion process, and thus becomes carcinogenic along with benzene in the gasoline.

Today, about 33 percent of gasoline is composed of aromatics by volume... Worse yet,

the aromatics tend to reduce the effectiveness of catalytic converters....By reducing the

amount of aromatics by volume, you substantially reduce the amount of carbon

monoxide, hydrocarbons, and nitrogen oxide emitted into the atmosphere...Fortunately,

there are other choices than aromatics to maintain octane level in gasoline. Guess what

they are? The oxygenated fuel additives.” 

“...Fuels high in aromatics cause deposits in the combustion chamber interfering with

combustion and increasing emissions. Aromatics have higher carbon content than the

rest of gasoline, so gasoline high in aromatics contributes more to global warming. 

Aromatics were only about 20 percent of fuel in 1970, but percentages have increased

substantially because the aromatics have been used to replace the octane that was lost as

a result of the lead phase-down.” (emphasis added)

The refining industry has informed the BRP that it will, in fact, increase use of aromatics in gasoline if

the oxygenate provisions of the RFG program are removed. The BRP recommendations further state that,

in most instances, oxygenates can be “effectively” replaced by aromatics. This position is directly

counter to the vast weight of evidence on the harmful effects of aromatics and the positive air quality

effects of oxygenates. Further, it is in direct conflict with the clear intent of Congress to improve U.S. air

quality by restricting use of aromatics.

The BRP has not heard evidence supporting the “safe and effective” use of increased levels of aromatics

in gasoline. In fact, according to evidence presented to the BRP on March 1-2, 1999, by William J. Piel,

Technical Director of the Clean Fuels Development Coalition (CFDC), increased use of aromatics will

lead directly to increases in air toxic emissions, exhaust VOC emissions, combustion chamber deposits,

carbon monoxide emissions, and worsen fuel factors contributing to vehicle performance (i.e. the

driveability index). Use of aromatics will also increase VOC emissions at both stationary and mobile

sources.

In fact, the BRP majority’s apparent willingness to accept higher aromatic levels runs directly counter to

Congressional intent. In his October 27, 1990 statement in support of the CAAA Conference report,
94

Senate Environment and Public Works Committee member David Durenberger stated that the

performance standard for post-2000 RFG should logically lead to a 25 percent or lower cap on aromatics.

According to Durenberger;

“The so-called formula gasoline which contains a cap on benzene at one percent and a

cap on aromatics at 25 percent should achieve substantial reductions in the aggregate

amounts of the five [toxic] pollutants...After the year 2000, the situation is different

because the Administrator is to choose the performance standard for toxics which

reflects the maximum reduction in toxic emissions that is feasible taking cost into

account. The formula gasoline may well achieve a reduction in toxics which exceeds 20

percent, and if so, whatever it does achieve would be a floor for the performance

standards after the year 2000 (emphasis added). In this Senator’s view, controls on

benzene and aromatics more stringent than those in the formula gasoline are certainly

feasible...The performance standards and the formula stated explicitly in the legislation

are only minimum requirements.” 

As a Nebraska state official and Panel member, I find it troubling that the majority of the BRP members

have chosen to ignore such evidence -- as well as the clear intent of Congress -- in its recommendation to

remove the oxygenate standard from RFG. It also concerns me that the BRP recommendation regarding

the oxygenate standard will likely lead directly to the increased use of aromatics – compounds

universally condemned for their harmful effects on air quality. 

Finally, the legislative history clearly shows that Congress specifically required the use of oxygenates in

gasoline for other important public policy goals: national energy security through the reduction in oil

imports; and, stimulating domestically produced renewable fuels made from agricultural products. 

As Sen. Harkin stated;

“[Use of oxygenates] will reduce our health care costs. We can have reduced farm

support costs. And reduced oil imports. By lowering reformer severity and aromatics

content as a means of achieving octane, and replacing it with high octane oxygenates,

you conserve large quantities of oil in two ways – first, savings in gasoline because of

the lower severity of the refining operation of the base gasoline; and second, straight

physical displacement of gasoline by oxygenates. This amendment will save millions of

barrels of oil every year.” 

And in a May 2, 1990 “Dear Colleague” letter, Representatives Bill Richardson (now Energy Secretary)

and Ed Madigan urged their colleagues to support the House version of the Daschle-Dole RFG provision. 

They wrote;

“Cleaner gasoline also slashes foreign imports. Today’s gasoline relies on imported

aromatic compounds. When we replace these compounds with domestically produced

alcohols and ethers made from corn, wheat, barley and other crops, we shift trade from

OPEC to our farmers. According to the GAO, this new market could save taxpayers over

$1.2 billion that is now spent annually on farm price supports.” 
95

These and other references make it clear that Congress thoughtfully considered and debated the benefits

of reducing aromatics and requiring the use of oxygenates in RFG. Based on the weight of evidence

presented to the BRP, I remain convinced that maintenance of the oxygenate standard is necessary to

ensure cleaner air and a healthier environment. I am also convinced that water quality must be better

protected through significant improvements to gasoline storage tanks and containment facilities. 

Therefore, because it is directly counter to the weight of the vast majority of scientific and technical

evidence and the clear intent of Congress, I must respectfully disagree with the BRP

recommendation that the oxygenate provisions of the RFG Program be removed. I also request that

the final report from the BRP include a recommendation to place a cap on the use of aromatics in

gasoline at 25 percent by volume, in keeping with the Panel’s commitment to preserve air quality

improvements.

Todd Sneller serves as Administrator of the Nebraska Ethanol Board, a state agency. He is the past

chairman of the Clean Fuels Development Coalition, and currently serves as the Nebraska

representative of the 22 state Governors’ Ethanol Coalition. Mr. Sneller was appointed to the EPA

Blue Ribbon Panel in December 1998.
96

Lyondell Chemical Company's Dissenting Report

Summary

While the Panel is to be commended on a number of good recommendations to improve the current

underground storage tank regulations and reduce the improper use of gasoline, the Panel’s

recommendations to limit the use of MTBE are not justified. 

Unfortunately, there appears to be an emotional rush to judgement regarding the use of MTBE. The

recommendation to reduce the use of MTBE substantially is unwarranted for the following four reasons:

Firstly, the Panel was charged to review public health effects posed by the use of oxygenates, particularly

with respect to water contamination. The Panel did not identify any increased public health risk

associated with MTBE use in gasoline.

Secondly, no quantifiable evidence was provided to show the environmental risk to drinking water from

leaking underground storage tanks (LUST) will not be reduced to manageable levels once the 1998

LUST regulations are fully implemented and enforced. The water contamination data relied upon by the

Panel is largely misleading because it predates the implementation of the LUST regulations.

Thirdly, the recommendations will not preserve the air quality benefits achieved with oxygenate use in

the existing RFG program. The air quality benefits achieved by the RFG program will be degraded

because they fall outside the control of EPA's Complex Model used for RFG regulations and because the

alternatives do not match all of MTBE's emission and gasoline quality improvements. 

Lastly, the Panel's recommendation options depend upon the use of alternatives that have not been

adequately studied for air quality and health risk impacts. These alternatives will also impose an

unnecessary additional cost of 1 to 3 billion dollars per year (3 – 7 c/gal. RFG) on consumers and society

without quantifiable offsetting social benefits or avoided costs with respect to water quality in the future.

Discussion of Issues

No increase in public health risk associated with the use of MTBE has been identified.

Based on the Panel's review of the available health studies, the Panel did not identify any increased

health risk associated with MTBE's normal use in gasoline and the Panel's review is best summarized by

the following paragraph from the Issue Summary E, “Comparing the Fuel Additives.”

“In terms of neurotoxicity and reproductive effects, inhalation toxicity testing to date generally has not

shown MTBE to be any more toxic than other components of gasoline. At very high doses, MTBE has

caused tumors in two species of rat and one species of mouse at a variety of sites; it is uncertain,

however, whether these effects can be extrapolated to humans. The International Agency for Research

on Cancer (IARC) and the National Institute of Environmental Health Sciences (NIEHS) have indicated

that at this time there are not adequate data to consider MTBE a probable or known human carcinogen."
35 Sausville, Paul, Dale Marx and Steve Crimaudo: A Preliminary State Survey with Estimates based on a

Survey of 17 State databases of early 1999. ASTSWMO UST Task Force, 11th Annual EPA UST/LUST National

Conference, March 15–17, 1999. Daytona Beach, Florida.

36 Keller, Arturo, et. al. Health & Environmental Assessment of MTBE, Report to the Governor and

Legislature of the State of California as Sponsored by SB 521. November 1998.

37 "Overview of Fuel Oxygenate Development", William J. Piel For Lyondell Chemical Co., Presentation to

the EPA's Blue Ribbon Panel, January 22, Arlington, VA.

97

No quantifiable evidence has been provided to show that full compliance with the 1998 LUST

regulations will not achieve its purpose of substantially reducing the release of gasoline, and

thereby MTBE, from UST systems today and in the future.

The Panel states that enhanced UST programs will not give adequate assurance that water supplies will

be protected. However, this statement is made without any quantifiable analysis or support. The facts

are that most MTBE detects are very low level concentrations and have occurred prior to UST systems

being upgraded to meet the 1998 deadlines. The MTBE detection data presented to the Panel by the

USGS was collected between 1988 and 1998 when most UST systems were still out of compliance. In

addition, data summarized by the Association of State and Territorial Solid Waste Management Officials

(ASTSWMO) shows that less than 50 percent of all UST’s were in compliance prior to 1998 and that as

recent as 1996 only 30 percent were in compliance.35 Therefore, the detection data reflects a time period

before most of the underground tanks were upgraded. 

In addition, the risk of drinking water contamination by MTBE and other gasoline constituents has been

greatly reduced with the onset of LUST regulation compliance. The UC Davis study36 which was

presented to the PANEL estimates that tank failure rates (leak occurrences) decrease by over 95 percent

(from 2.6 percent failures per year for non-upgraded tanks to 0.07 percent per year for upgraded tanks)

once UST systems are upgraded to meet the current LUST regulations. Also, with the required

installation of early leak detection monitoring, the time between when a leak occurs and when it is

detected will now be significantly reduced. As a result, the amount of gasoline released from a new

leaking site before it has been remediated is substantially minimized. Both of these effects combined

should lead to substantial reductions (orders of magnitude) in the amount of gasoline and MTBE that

escapes undetected from the UST population which therefore makes it a much more manageable situation

for protecting drinking water supplies.

The recommendations fail to recognize the full emission benefits from using MTBE and oxygenates

in RFG, and that the alternatives do not equal the emission reductions and combustion enhancing

blending properties of MTBE in gasoline. Therefore, a reduction in MTBE use will result in a net

loss in air quality.

Although the Panel was charged with "examining the role of oxygenates in meeting the nation's goal of

clean air" and "evaluating each product's efficiency in providing clean air benefits and the existence of

alternatives," the Panel did not identify and quantify all the emission benefits realized when oxygenates

are used to make cleaner burning and low polluting gasolines. Neither was the Panel able to identify

combinations of alternatives that could match both the emission reductions and the combustion

enhancing blending properties of MTBE in gasoline. The Panel did not recognize the fact that the simple

use of oxygenates along with a vapor pressure reduction were the only requirements used to achieve the

ozone precursor reduction goals in the first three years of a very successful RFG program.37 Since all

other alternatives have one or more inferior properties as compared to MTBE in gasoline, it would be

difficult if not nearly impossible to achieve the same real air quality efficiency provided by MTBE. And
38 "Staff Report: Proposed Amendments to the California Regulation Requiring Deposit Control Additives in

the Motor Vehicle Gasoline” Calif. Environ. Protection Agency, Air Resources Board, Aug 7, 1998; "Benefits of

the Federal RFG Program And Clean Burning Fuels with Oxygenates", William J. Piel of Lyondell Chemical Co.,

Presentation to EPA Blue Ribbon Panel, March 1, 1999, Boston.

98

since sulfur reductions are also expected to occur under other fuel regulations, it would be a doubleaccounting of emissions benefits if sulfur reductions in RFG are to be used to compensate or make-up for

any increase of emissions resulting from reduced oxygenate use in RFG.

Beyond reducing VOC's, NOx and toxics, improving gasoline properties through the use of oxygenates

reduce many other vehicles pollutants such as CO (carbon monoxide), PM (particulate matter) and CO2

(carbon dioxide) as well as the ozone reactivity of VOC's. Also, gasoline property changes associated

with oxygenate use in RFG provide additional emission reductions of VOC, NOx, toxics and CO (an

ozone precursor) over the life of the vehicle by lowering combustion chamber deposits and therefore the

vehicle's emissions deterioration rates over time. Since none of these additional emission reductions are

reflected or controlled in EPA's Complex Emissions Model used for RFG, reducing MTBE in RFG will

result in a loss of these extra emission benefits.38 

Unfortunately, the Panel recommendations limit themselves to only meeting the regulatory requirements

established in EPA's existing RFG rules and did not focus on capturing all the real world emission

benefits associated with MTBE's use in RFG. Though the Panel recommends reducing the use of

oxygenates in RFG, they failed to explain how equivalent air quality is to be maintained when the only

identifiable fuel alternatives cannot match all of MTBE's emission reductions and combustion enhancing

blending properties in gasoline. Therefore, replacing MTBE with the alternatives under the current

recommendations will contribute to a net loss in air quality with regards to Peak Ozone levels, PM, toxics

and CO2 (greenhouse gas) in addition to higher costs.

Alternatives have not been adequately studied for their health risk impacts, availability or their

cost effectiveness in RFG 

From a scientific, policy, and political perspective, no one should rush to judgement on MTBE without a

thorough evaluation of the alternatives. The Panel cannot afford to be wrong about MTBE's benefits or

deficiencies. As a matter of sound public policy, any alternative needs to be held up to the same rigorous

examination as MTBE, while adhering to the following criteria. 

& To assure the public that any alternative will produce the same real air quality benefits as MTBE.

& That any alternative will be abundantly and economically available.

& That any alternative will not be a probable or known human carcinogen nor increase the risks to

human health.

These criteria are consistent with the Panel's recommendation to investigate more fully any major new

additives to gasoline prior to its introduction and therefore should equally apply to the alternatives

already identified by the Panel, namely Ethanol, Alkylates, and Aromatics. The expanded use of these

alternatives should not occur without a more rigorous analysis of the impacts on health, air quality, and

water quality as well as their availability and costs.
99

LIST OF PANEL MEMBERS AND PARTICIPANTS

Members of the Blue Ribbon Panel

Dan Greenbaum, Health Effects Institute, Chair

President

Health Effects Institute

955 Massachusetts Ave.

Cambridge, MA 02139

(617) 876-6700

Fax: (617) 876-6709

dgreenbaum@healtheffects.org

Mark Beuhler, Metropolitan Water District, So. California

Director of Water Quality

Metropolitan Water District of Southern California

P.O. Box 54153

Los Angeles, CA 90071

(213) 217-6647 

Fax: (213) 217-6951

mbeuhler@mwd.dst.ca.us

Robert Campbell, CEO, Sun Oil

Chairman and CEO 

Sunoco, Inc. 

1801 Market Street

Philadelphia, Pennsylvania 19103-1699

(215) 977-3871

Fax: (215) 977-3559

ann_l_williams@sunoil.com

Patricia Ellis, Delaware Department of Natural Resources and Environmental Control

Hydrologist

Delaware Department of Natural Resources and Environmental Control

Air and Waste Management Division

391 Lukens Drive

New Castle, DE 19720

(302) 395-2500

Fax: (302) 395-2601

pellis@dnrec.state.de.us
100

Linda Greer, Natural Resources Defense Council

Senior Scientist

Natural Resources Defense Council

1350 New York Ave., N.W.

Washington, D.C. 20005 

(202) 289-6868

Fax: (202) 289-1060

lgreer@nrdc.org

Jason Grumet, NESCAUM

Executive Director

NESCAUM

129 Portland Street

Boston, MA 02114

(617) 367-8540, ext. 216

Fax: (617) 742-9162

jgrumet@nescaum.org

Anne Happel, Lawrence Livermore National Laboratory

Environmental Scientist

Lawrence Livermore National

Laboratory, L-542

7000 East Avenue

Livermore, CA 94550

(925) 422-1425

Fax (925) 422-9203

happel1@llnl.gov

Carol Henry, American Petroleum Institute

Director, Health and Environmental Sciences 

American Petroleum Institute

1220 L Street, N.W.

Washington, D.C. 20005-4070

(202) 682-8308

Fax: (202) 682-8270

henrycj@api.org

Michael Kenny, California Air Resources Board

Executive Officer

California Air Resources Board

P.O. Box 2815

Sacramento, CA 95812 

(916) 445-4383

Fax: (916) 322-6003

mkenny@arb.ca.gov
101

Robert Sawyer, University of California, Berkeley

Professor, Graduate School

Mechanical Engineering Department

University of California at Berkeley

72 Hesse Hall

Berkeley, CA 94720-1740

(510) 642-5573

Fax: (510) 642-1850

rsawyer@newton.berkeley.edu

Todd Sneller, Nebraska Ethanol Board

Executive Director

Nebraska Ethanol Board

301 Centennial Mall South

Fourth Floor

Lincoln, NE 69509

(402) 471-2941

Fax: (402) 471-2470

sneller@nrcdec.nrc.state.ne.us

Debbie Starnes, Lyondell Chemical

Senior Vice President, Intermediate Chemical

Lyondell Chemical Company

1221 McKinney Street, Suite 1600

Houston, TX 77010

(713) 652-7370

Fax: (713) 652-4538 

debbie.starnes@lyondellchem.com

Ron White, American Lung Association

Director, National Programs 

American Lung Association

1726 M St., NW

Suite 902

Washington, DC 20036

(202) 785-3355

Fax: (202) 452-1805

rwhite@lungusa.org
102

Federal Representatives (Non-Voting):

Robert Perciasepe, Air and Radiation, US Environmental Protection Agency

Assistant Administrator

Office of Air and Radiation

US Environmental Protection Agency

401 M Street, SW

Washington, DC 20460

(202) 260-7400

Fax: (202) 260-5155

perciasepe.robert@epa.gov

Roger Conway, US Department of Agriculture

Director, Office of Energy Policy and New Uses

U.S. Department of Agriculture

1800 M Street NW, Room 4129 N

Washington, DC 20036

(202) 694-5020

Fax: (202) 694-5665

rkconway@econ.ag.gov

Cynthia Dougherty, Drinking Water, US Environmental Protection Agency

Director, Office of Ground Water and Drinking Water

US Environmental Protection Agency

401 M Street SW

Washington, DC 20460

(202) 260-5543

Fax (202) 260-4383

dougherty.cynthia@epa.gov

William Farland, Risk Assessment, US Environmental Protection Agency

Director, National Center for Environmental Assessment

Office of Research and Development

US Environmental Protection Agency

Washington, DC 20460

(202) 564-3319

Fax (202) 565-0090

farland.william@epa.gov

Barry McNutt, US Department of Energy 

Senior Policy Analyst

Department of Energy

1000 Independence Avenue

Room H021

Washington, DC 20585 

(202) 586-4448

Fax: (202) 586-4447

barry.mcnutt@hq.doe.gov
103

Margo Oge, Mobile Sources, US Environmental Protection Agency

Director, Office of Mobile Sources

Office of Air and Radiation

US Environmental Protection Agency

401 M Street SW

Washington, DC 20460

(202) 260-7645

Fax (202) 260-3730

oge.margo@epa.gov

Sammy Ng, Underground Tanks, US Environmental Protection Agency

Acting Director, Office of Underground Storage Tanks

US Environmental Protection Agency

401 M Street SW 

Washington, DC 20460

(703) 603-9900

Fax (703) 603-0175

ng.sammy@epa.gov

Mary White, Agency for Toxic Substances and Disease Registry

Epidemiologist Chief

Health Investigations Branch

Agency for Toxic Substances and Disease Registry

1600 Clifton Road

Mail Stop E-31

Atlanta, GA 30333

(404) 639-6229

Fax (404) 639-6219

mxw5Wcdc.gov

John Zogorski, US Geological Survey

Project Chief, National Water Quality Assessment Program

US Geological Survey

1608 Mountain View Road

Rapid City, SD 57702

(605) 355-4560 X214

Fax: (605) 355-4523

jszogors@usgs.gov
104

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111

GLOSSARY OF TERMS

ACRONYMS

AQMD Air Quality Management District

AS Air Sparging

AST Aboveground Storage Tank

ASTM American Society for Testing & Material

AWWARF American Water Works Association Research Foundation

BTEX Benzene, Toluene, Ethylbenzene, and Xylene

Btu British Thermal Unit

CAA Clean Air Act

CAAA Clean Air Act Amendments of 1990

CAFÉ Corporate Average Fuel Economy

CalEPA California Environmental Protection Agency

CARB California Air Resources Board

CaRFG California Reformulated Gasoline

CEC California Energy Commission

CG Conventional Gasoline

CIIT Chemical Industry Institute of Toxicology

CO Carbon Monoxide

CO2 Carbon Dioxide

CWSRF Clean Water State Revolving Fund

DIPE Di-isopropyl Ether

DOE U.S. Department of Energy

DOT U.S. Department of Transportation

DWSRF Drinking Water State Revolving Fund

EIA U.S. Energy Information Administration

EPA U.S. Environmental Protection Agency

EPACT Energy Policy Act of 1992

ETBE Ethyl Tertiary Butyl Ether

E10 10% Ethanol/90% Gasoline by volume

FCC Fluid Catalytic Cracked

HC Hydrocarbons

HEI Health Effects Institute

IARC International Agency for Research on Cancer

ILEV Inherently Low Emission Vehicle

LEV Low Emission Vehicle

LLNL Lawrence Livermore National Laboratory

LUST Leaking Underground Storage Tank

MNA Monitored Natural Attenuation

MTBE Methyl Tertiary Butyl Ether

NAAQS National Ambient Air Quality Standards

NAPL Non-Aqueous Phase Liquid
112

NAWQA National Water Quality Assessment Program

NESCAUM Northeast States for Coordinated Air Use Management

NMOG Non-Methane Organic Gases

NOx Oxides of Nitrogen

NRC National Research Council

OMS U.S. Environmental Protection Agency, Office of Mobile Sources

OSTP White House Office of Science and Technology

OUST U.S. Environmental Protection Agency, Office of Underground Storage Tanks

OXY Winter Oxyfuel Program

PADD Petroleum Administration for Defense Districts

PAN Peroxyacetyl Nitrate

PM Particulate Matter

POM Polycyclic Organic Matter

ppb Parts Per Billion

ppm Parts Per Million

psi Pounds Per Square Inch (pressure)

RBCA Risk-Based Corrective Action

RFG Reformulated Gasoline

RVP Reid Vapor Pressure

SDWA Safe Drinking Water Act

SIP State Implementation Plan

SPCC Spill Control and Counter Control 

SULEV Super Ultra Low Emission Vehicle

SVE Soil Vapor Extraction

TAME Tertiary Amyl Methyl Ether

TBA Tertiary Butyl Alcohol

TLEV Transitional Low Emission Vehicle

ULEV Ultra Low Emission Vehicle

USDA U.S. Department of Agriculture

U.S. EPA U.S. Environmental Protection Agency

USGS United States Geological Survey

T50 50% Distillation Temperature

T90 90% Distillation Temperature

UST Underground Storage Tank

VOC Volatile Organic Compound

ZEV Zero Emission Vehicle
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TERMS

Additives: Chemicals added to fuel to improve and maintain fuel quality. Detergents and corrosion

inhibitors are examples of gasoline additives.

Air Toxics: Toxic air pollutants defined under Title II of the CAA, including benzene, formaldehyde,

acetaldehyde, 1.3 butadiene, and polycyclic organic matter (POM). Benzene is a constituent of

motor vehicle exhaust, evaporative, and refueling emissions. The other compounds are exhaust

pollutants.

Alcohols: Organic compounds that are distinguished from hydrocarbons by the inclusion of a hydroxl

group. The two simplest alcohols are methanol and ethanol.

Aldehydes: A class of organic compounds derived by removing the hydrogen atoms from an alcohol. 

Aldehydes can be produced from the oxidation of an alcohol.

Alkanes: See Paraffins.

Alkylate: The product of an alkylation reaction. It usually refers to the high octane product from

alkylation units. This alkylate is used in blending high octane gasoline.

Aromatics: Hydrocarbons based on the ringed six-carbon benzene series or related organic groups. 

Benzene, toluene, ethylbenzene, and xylene are the principal aromatics, commonly referred to as

the BTEX group. They represent one of the heaviest fractions in gasoline.

Attenuation: The reduction or lessening in amount (e.g., a reduction in the amount of contaminants in a

plume as it migrates away from the source). Attenuation occurs as a result of in-situ processes

(including biodegradation, dispersion, dilution, sorption, volatilization), and chemical or

biological stabilization, transformation, or destruction of contaminants.

Benzene: Benzene is a six-carbon aromatic that is common gasoline component. Benzene has been

identified as toxic and is a known carcinogen.

Biodegradation: A process by which microbial organisms transform or alter (through metabolic or

enzymatic action) the structure of chemicals introduced into the environment.

Biomass: Renewable organic matter, such as agricultural crops, crop-waste residues, wood, animal and

municipal wastes, aquatic plants, or fungal growth, used for the production of energy.

British Thermal Unit (Btu): A standard unit for measuring heat energy. One Btu represents the

amount of heat required to raise one pound of water one degree Fahrenheit (at sea level).

Butane: An easily liquefied gas recovered from natural gas. Used as a low-volatility component of

motor gasoline, processed further for a high-octane gasoline component, used in LPG for

domestic and industrial applications, and used as a raw material for petrochemical synthesis.
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Butyl Alcohol: Alcohol derived from butane that is used in organic synthesis and as a solvent.

CAA: The original Clean Air Act was signed in 1963, setting emissions standards for stationary sources. 

The CAA was amended several times, most recently in 1990. The Amendments of 1970

introduced motor vehicle emission standards. Criteria pollutants included lead, ozone, CO, SO2,

NOX, and PM, as well as air toxics. In 1990, reformulated gasoline (RFG) and oxygenated

gasoline (OXY) provisions were added. The RFG provision requires use of RFG all year in

certain areas. The OXY provision requires the use of oxygenated gasoline during certain

months, when CO and ozone pollution are most serious. The regulations also require certain

fleet operators to use clean-fuel vehicles in 22 cities.

California Low Emissions Vehicle Program: State requirement for automakers to produce vehicles

with fewer emissions than current EPA standards. The five categories of the Program, from least

to most stringent are as follows: TLEV; LEV; ULEV; SULEV; and ZEV.

Carcinogens: Chemicals and other substances known to cause cancer.

Distillation Curve: The percentages of gasoline that evaporate at various temperatures. The distillation

curve is an important indicator for fuel standards such as volatility (vaporization).

Ethanol: Can be produced chemically from ethylene or biologically from the fermentation of various

sugars or from carbohydrates found in agricultural crops and cellulosic residues from crops or

wood. Ethanol is used in the United States as a gasoline octane enhancer and oxygenate. It

increases octane 2.5 to 3.0 numbers at 10 percent concentration. Ethanol also can be used in

higher concentrations in alternative-fuel vehicles optimized for its use.

Ethers: A family of organic compounds composed of carbon, hydrogen, and oxygen. Ether molecules

consist of two alkyl groups linked to one oxygen atom. Light ethers such as ETBE, MTBE,

TAME, and DIPE have desirable properties as gasoline blendstocks and are used as oxygenates

in gasoline.

Ethyl Tertiary Butyl Ether (ETBE): An aliphatic ether similar to MTBE. This fuel oxygenate is

manufactured by reacting isobutylene with ethanol. Having high octane and low volatility

characteristics, ETBE can be added to gasoline up to a level of approximately 17 percent by

volume. 

E10: Ethanol/gasoline mixture containing 10 percent denatured ethanol and 90 percent gasoline, by

volume.

Evaporative Emissions: Hydrocarbon vapors that escape from a fuel storage tank, a vehicle fuel tank,

or vehicle fuel system.

Exhaust Emissions: Materials that enter the atmosphere through the exhaust, or tailpipe, of a vehicle. 

Exhaust emissions include carbon dioxide (and water vapor), carbon monoxide, unburned fuel,

products of incomplete combustion, fuel contaminants, and the combustion products of

lubricating oils.
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Feedstock: Any material converted to another form of fuel or energy product. 

Fungible: A term used within the oil refining industry to denote products that are suitable for

transmission by pipeline.

Ground Water: The water contained in the pore spaces of saturated geologic media. Ground water can

be confined by overlying less permeable strata (confined aquifer) or open to the atmosphere

(water table or unconfined aquifers). 

In-situ: In its original place; unmoved; unexcavated; remaining in the subsurface.

Methyl Tertiary Butyl Ether (MTBE): An ether manufactured by reacting methanol and isobutylene. 

The resulting ether has high octane and low volatility. MTBE is a fuel oxygenate and is

permitted in unleaded gasoline up to a level of 15 percent by volume.

National Ambient Air Quality Standards: Ambient standards for criteria air pollutants specifically

regulated under the CAA. These pollutants include ozone, particulate matter, carbon monoxide,

nitrogen dioxide, sulfur dioxide, and lead.

Neat Fuel: Fuel that is free from admixture or dilution with other fuels.

Neat Alcohol Fuel: Straight or 100 percent alcohol (not blended with gasoline), usually in the form of

either ethanol or methanol.

Nonattainment Area: A region, determined by population density in accordance with the U.S. Census

Bureau, which exceeds minimum acceptable NAAQS for one or more “criteria pollutants.” Such

areas are required to seek modifications to their State Implementation Plans (SIPs), setting forth

a reasonable timetable using EPA-approved means to achieve attainment of NAAQS for these

criteria pollutants by a certain date. Under the CAA, if a nonattainment area fails to attain

NAAQS, EPA may superimpose a FIP with stricter requirements or impose fines, construction

bans, cutoffs in Federal grant revenues, etc., until the area achieves the applicable NAAQS.

Octane Enhancer: Any substance such as MTBE, ETBE, toluene, xylene and alkylates that is added to

gasoline to increase octane and reduce engine knock.

Oxyfuel Program: Nonattainment areas for carbon monoxide are required to use oxygenated fuel

during the winter season.

Oxygenate: A term used in the petroleum industry to denote fuel additives containing hydrogen, carbon,

and oxygen in their molecular structure. Includes ethers such as MTBE and ETBE and alcohols

such as ethanol and methanol.

Oxygenated Gasoline: Gasoline containing an oxygenate such as MTBE or ethanol. The increased

oxygen content may promote more complete combustion, thereby reducing tailpipe emissions of

CO.
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Paraffins: Also referred to as Alkanes, a group of chain saturated aliphatic hydrocarbons, including

methane, ethane, propane, butane, and alkanes (not including cycloalkanes). 

Particulate Matter (PM): A generic term for a broad class of chemically and physically diverse

substances that exist as discrete particles (liquid droplets or solids) over a wide range of sizes; a

NAAQS pollutant.

Recalcitrant: Unreactive, nondegradable; refractory. Slowly degraded compounds.

Reformulated Gasoline (RFG): Gasolines that have had their compositions and/or characteristics

altered to reduce vehicular emissions of pollutants, particularly pursuant to EPA regulations

under the CAA.

Reid Vapor Pressure (RVP): A standard measurement of a liquid’s vapor pressure in psi at 100 degrees

Fahrenheit. It is an indication of the propensity of the liquid to evaporate.

State Implementation Plan (SIP): Plan that a state must submit to EPA under the CAA to demonstrate

compliance to NAAQS.

Tertiary Amyl Methyl Ether (TAME): An ether based on reaction of C5 olefins and methanol.

Toluene: Basic aromatic compound derived from petroleum and used to increase octane. A

hydrocarbon commonly purchased for use in increasing octane.

Toxic Emission: Any pollutant emitted from a source that can negatively affect human health or the

environment.

Toxics: Pollutants defined by the CAAA, including benzene, formaldehyde, acetaldehyde, 1,3 butadiene,

and polycyclic organic material. Benzene is emitted both in exhaust and evaporative emissions;

the other compounds are exhaust emissions.

Volatile Organic Compounds (VOCs): Reactive gases released during combustion or evaporation of

fuel and regulated by EPA. VOCs react with NOX in the presence of sunlight and form ozone.

Volatilization: The process of transfer of a chemical from the aqueous or liquid phase to the gas phase. 

Solubility, molecular weight, vapor pressure, mixing of the liquid, and the nature of the gasliquid interface affect the rate of volatilization.

Vapor Pressure or Volatility: The tendency of a liquid to pass into the vapor state at a given

temperature. With automotive fuels, volatility is determined by measuring RVP. 

Wellhead: The area immediately surrounding the top of a well, or the top of the well casing.

Wellhead Protection Area: The recharge area surrounding a drinking water well or wellfield, which is

protected to prevent contamination of a well.