Underground Heating Oil and
   Motor Fuel Tanks Exempt from
Regulation Under Subtitle I of RCRA
             A Study for
          Report to Congress
  U.S. Environmental Protection Agency
  Office of Underground Storage Tanks
           Washington, D.C.
              May 1989
                                         Printed on Recycled Paper

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                                                 510R92003
 UNDERGROUND HEATING OIL AND MOTOR FUEL TANKS

EXEMPT FROM REGULATION UNDER SUBTITLE I OF RCRA:


                  A STUDY FOR

              REPORT TO CONGRESS
                  Prepared by:

      Office of Underground Storage Tanks
      U.S.  Environmental Protection Agency
               401 M Street, S.W.
            Washington,  D.C.   20460
                   May 1989

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                                 DISCLAIMER

     This report was prepared under contract  to an agency of the United States
Government.  Neither the United States Government nor any of its employees,
contractors, subcontractors, or their employees makes any warranty,  expressed
or implied, or assumes any legal liability or responsibility for any third
party's use of or the results of such use of  any information,  apparatus,
product, or process disclosed in this report, or represents that its use by
such third party would not infringe on privately owned rights.

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                              TABLE OF CONTENTS
LIST OF EXHIBITS

EXECUTIVE SUMMARY
                                                                 PAGE
SECTION 1  BACKGROUND AND STUDY APPROACH                          1-1


SECTION 2  DESCRIPTION OF EXEMPT HEATING OIL AND MOTOR FUEL       2-1
           TANK SYSTEMS

     2.1  Size of the Population                                  2-1

     2.2  Geographic Location                                     2-4

     2.3  Technical Characteristics                               2-5

     2.4  Current Management Practices                            2-16

     2.5  Summary Description of Exempt Tank Systems              2-19

 iCTION 3  EXTENT OF RELEASES FROM EXEMPT HEATING OIL AND         3-1
           MOTOR FUEL TANK SYSTEMS               :

     3.1  Sources of Information                                  -?"1-

     3.2  Documented Releases                                     3-2

     3.3  Additional Information on Releases                      3-14

     3.4  Comparison of Exempt Tank Systems'and Regulated         3-20
          USTs Involved in Reported Releases

     3.5  Potential for Releases                                  3-22

SECTION 4  POTENTIAL IMPACTS ON HUMAN HEALTH AND THE              4-1
           ENVIRONMENT FROM PRODUCTS RELEASED FROM EXEMPT
           HEATING OIL AND MOTOR FUEL TANK SYSTEMS

     4.1  Toxicities of Products Stored in Exempt Tank            4-1
          Systems

     4.2  Fate and Transport of Released Products                 4-4

     4.3  Summary of Potential Risks to Human Health              4-6
          and the Environment
                                     iii

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                        TABLE OF CONTENTS (Continued)
SECTION 5  STATE AND LOCAL REGULATION OF EXEMPT HEATING OIL
           AND MOTOR FUEL TANK SYSTEMS

     5.1  State Regulations

     5.2  Local Regulations

     5.3  Summary
PAGE

 5-1


 5-1

 5-4

 5-4


 R-l
TECHNICAL APPENDICES
APPENDIX A  DETERMINATION OF POPULATION SIZE AND
            CHARACTERISTICS OF EXEMPT TANK SYSTEMS

     A.I  Exempt Heating Oil Tank Systems

     A. 2  Exempt Motor Fuel TanV Systems         :

     A. 3  State UST Notification Data Bases
 A-.l


 A-l

 A-11

 A-13
APPENDIX B  SOURCES OF INFORMATION ABOUT EXTENT OF RELEASES
 B-l
APPENDIX C  POTENTIAL IMPACTS ON HUMAN HEALTH AND THE             C-l
            ENVIRONMENT FROM PRODUCTS RELEASED FROM
            EXEMPT HEATING OIL AND MOTOR FUEL TANK SYSTEMS

     C.I  Description of Motor Fuels and Heating Oils and         C-l
          Their Potential Health Effects

     C.2  Fate and Transport of Released Petroleum Products       C-10

     C.3  Hazard Potential                                        C-26
APPENDIX D  SOURCES OF STATE AND LOCAL STATUTES AND CODES

APPENDIX E  DEFINITION OF TERMS

REFERENCES FOR APPENDICES

                                      iv
 D-l

 E-l

RA-1

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                              LIST OF EXHIBITS
 EXHIBIT

Section 2

   2-1


   2-2


   2-3


   2-4


   2-5


   2-6


   2-7


   2-8


   2-9


Section 3

   3-1


   3-2


   3-3


   3-4


   3-5
                                 Tl'I'lJt
                                                      PAGE
Population Size of Exempt Ta^Jc Systems and Regulated   2-2
USTs

Geographic Concentration of Exempt Heating Oil and     2-6
Motor Fuel Tank Systems

Geographic Concentration of Exempt Heating Oil and     2-7
Motor Fuel Tank Systems by Use Sector

Typical Exempt Residential or Farm Heating Oil         2-9
Tank System

One Possible Large Exempt Nonresidential Heating       2-11
Oil Tank System

Typical Exempt Residential or Farm Motor Fuel          2-12
Tank System

Comparison of Construction Material for Exempt         2-14
Tank Systems and Regulated "ISTs

Comparison of Age of Exempt Tank Systems and           2-15
Regulated USTs

Comparison of Capacity for Exempt Tank Systems and     2-17
Regulated USTs
Number of Reported Releases from Exempt Tank Systems   3-3
by Sector

Number of Reported Releases from Exempt Heating Oil    3-4
and Motor Fuel Tank Systems

Reports of Releases from Exempt Heating Oil and Motor  3-5
Fuel Tank Systems in Maryland

Reports of Releases from Exempt Heating Oil Tank       3-6
Systems in New York
The Frequency of Reported Releases from Exempt
Heating Oil Tank Systems by Geographic Region
3-8

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                        LIST OF EXHIBITS  (Continued)
 ESHIBIT
                  TITI.K
                                                      PAGE
   3-6         Quantity of Product Released from Exempt               3-10
               Heating Oil Tank Systems

   3-7         Location Within Exempt Heating Oil Tank                3-12
               •Systems Where Releases Occur

   3-8         Environmental Damages Reported from Exempt Tank        3-13
               System Releases

   3-9         Frequency of Use of Selected Corrective                3-15
               Action Techniques

   3-10        Summary of Meeting with Government Officials           3-17

   3-11        Summary of Selected Releases from Exempt Tank          3-19
               Systems

   3-12        Capacity of Exempt Tank Systems and Regulated          3-21
               USTs Reporting Releases

   3-13        Quantity of Product Released from Exempt and           3-23
               Regulated USTs

   3-14        Age of Exempt and Regulated USTs                       3-24
               Reporting Releases

Section 4

   4-1         Adverse Health Effects Associated with Exposures        4-3
               to Some Constituents of Motor Fuels and Heating
               Oils

   4-2         Schematic of Subsurface Environment                    4-5
Section 5

   5-1


   5-2
State Regulation of Exempt Heating Oil and Motor       5-2
Fuel Tank Systems

State and Local Regulation of Exempt Tank Systems       5-5
                                     vi

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                        LIST OF EXHIBITS  (Continued)
 EXHIBIT

Appendix A

   A-l


   A-2


   A-3


   A-4


   A-5



   A-6



   A-7


   A-8


   A-9


Appendix C

   C-l


   C-2



   C-3


   C-4
                  TITLE
Estimate of the Population Size of Exempt
Residential Heating Oil Tank Systems

Estimate of the Population Size of Exempt Multiple-
Family Heating Oil Tank Systems

Estimates of the Geographic Location of Exempt
Underground Residential Heating Oil Tank Systems

List of Contacts for SCS Engineers' Storage Tank
Installers Survey

Estimates of the Population Size of Underground
Commercial, Institutional, and Government Heating
Oil Tank Systems

Estimates of the Geographic Location of Exempt
Commercial, Institutional, and Government
Seating Oil Tank Systems

Reports of Exempt Military Tank Systems Used to
Heat Residential Buildings
PAGE
 A-2
 A-4
 A-5
 A-6
 A-8
 A-10
 A-12
Estimated Population Size of Exempt Residential Motor  A-14
Fuel Tank Systems

Summary of the Number of Registered Exempt Tank        A-16
Systems
Relative Concentrations of Hydrocarbons Present in a   C-3
Representative Sample of Crude Oil

Potential Adverse Health Effects Associated with       C-5
Exposures to Some Constituents of Motor Fuels end
Heating Oils

Concentrations (g/1) of Selected Toxic Constituents    C-6
of Heating Oils

Health-Based Criteria for Selected Toxic               C-8
Constituents of Motor Fuels and Heating Oils
                                     vii

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                        LIST OF EXHIBITS (Continued)
EXHIBIT

  C-5


  C-6

  C-7


  C-8


  C-9

  G-10
                  TI Tl .g
                                                      PAGE
Major Factors Affecting Transport of Free Product      C-12
in the Unsaturated Zone

Physical Properties of Motor Fuels and Heating Oils .   C-13

Major Factors Affecting Transport of Free Product      C-17
on the Surface of the Water Table

Ma^or Factors Affecting Transport of Water Soluble     C-20
Constituents in the Saturated Zone

Major Factors Affecting Transport of Vapors          ,  C-22

Major Fate Processes                                   C-24
                                    viii

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                              Jฃ&JฃUUTJ.VJฃ SUMMARY
     Subtitle I of the Resource and Conversation Act (RCRA) requires the U.S.
Environmental Protection Agency to develop a national program for regulation
of underground storage tanks (USTs) .  -Subtitle I excludes from regulation nine
types of underground tank systems including two that are the focus of this
study:

     •    Tank systems used for storing heating oil for consumptive use on the
          premises where stored; and

     •    Farm \or residential tank systems of 1,100 gallons or less capacity
          used for storing motor fuel for noncommercial purposes. ^

This study was undertaken to comply with Section 9009 (d) and (e) of RCRA,
which requires EPA to study the tanks listed above and to report to the
President and Congress whether these underground tank systems (hereafter,
referred to as exempt tank systems) should be subject to the provisions of
Subtitle I.                                          .  .            .      ;

     To provide the necessary information required to respond to Congress,
this investigation identifies the:                                     ,

     •    Size and geo^Taphic location of the population of exempt tank
          systems ;                                .

     •    Extent that exempt tank systems 'are known to leak and an assessment
          of their potential to leak;                         •.••,'-,

     m    Potential hazards to human health and the environment posed by
          releases of stored substances from exempt tank systems; and

     •    Extent of state and local regulation of exempt tank systems.

Study Approach

     The background study was conducted in three stages.  First, EPA assessed
the size, geographic location, and other characteristics of the exempt heating
oil and motor fuel tank population, including the extent of known releases
from such tank systems, using standard survey research techniques.  Second,
this assessment was reviewed by federal and state government officials and
underground storage industry representatives.  Finally, additional analyses,  "

     *• Subtitle I exempts these tank systems from regulation by excluding them
from the definition of underground storage tanks (USTs).  Therefore, when used
in this report, the term UST refers only to underground storage tanks
regulated under Subtitle I.

                                     ES-1

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 using supplemental data provided by these representatives,  were thereafter
 conducted to address comments received from this review.

      This study relies mainly on existing .data.   Some of the information
* obtained is useful to the analyses only if some  reasonable  assumptions are
 made.  To the extent possible, petroleum and underground storage experts from
 both industry and government were contacted regarding the validity of the
 assumptions used.

      The exempt tank systems addressed in this study are divided into two
 major types: motor fuel tank systems and heating oil tank systems.   Exempt
 motor fuel tank systems are subdivided into tank systems located at (1) farms
 and (2) residences.  Exempt heating oil tank systems are subdivided into tank
 systems used at (1) farms, (2) residences, and (3)  nonresidential facilities.
 Residential facilities include apartment complexes, condominiums,  towhhouses,
 and single-family homes.  Nonresidential facilities include commercial,
 institutional, government, manufacturing, and military facilities.   The
 distinction between motor fuels and heating oils and the breakdown of sectors
 among farms, residences, and nonresidential facilities correspond generally to
 the language of the statutory exemption in this  study.

 Characteristics of the Population of Exenpt Tank Systems

      The estimated population of exempt tank systems in the United States is
 about 3.1 million tanks, almost twice the number of USTs currently regulated
 under Subtitle I (1.7 mill',on).  The 3.1 million total population of exempt
 tanks breaks down into the following sectors*:
               *                                 (, <•'
 HeatingOilTanks (2.7 million tanks!             '
      (1)   Residential sector:            1.9  million tanks  (61%)

      (2)   Nonresidential sector:         0.8  million tanks  (25%)

      (3)   Farm sector:     .             0.04 million tanks  (1%)

 Motor Fuel Tanks (0.4 million tanks)

      (1)   Farm sector:                  0.3  million tanks  (10%)

      (2)   Residential sector:            0.1  million tanks  (3%)

      Geographically, heating oil tank systems are concentrated in the
 Northeast, where fuel oil is commonly used for heating;  relatively few exempt
       2 The precession and accuracy of these estimates could not be defined
 quantitatively.  Data quality objectives were set at the beginning of this
 study assuming that if tank system estimates are within a factor of two of the
 true population size, the errors in the estimates would not significantly
 affect the regulatory decisions to be made as a result of this report.

                                     ES-2

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heating oil tank systems are located in the West.   This observation applies
especially to residential heating oil tank systems.  Farm heating oil tank
systems are more uniformly distributed throughout  the country.   Exempt farm
motor fuel tank systems are concentrated in the North Central and West; the
Northeast contains the fewest of these tank systems.   The geographic
concentration of exempt residential motor fuel tank systems could not be
established with available data.
            *                                                                ซ.
     The technical and operational characteristics of exempt heating oil and ,
motor fuel tank systems are better understood if they are compared and
contrasted to those of regulated USTs.  The similarities and differences
between exempt tank systems and regulated USTs are summarized below.

Similarities:

     •    Most exempt tank systems and regulated USTs are constructed of steel
          and are not protected against corrosion;

     •    Existing exempt tank systems and regulated USTs have similar age
          distributions (most of them are over 15  years old); and

     •    Exempt nonresidential heating oil tanks  are similar to regulated
          tanks in size and gauge (thickness) of steel.

Differences:
          Most exempt residenv .al and farm tank systems have a storage
          capacity of less than 1,100 gallons.  These tanks, therefore,
          to be much smaller and made of lighter-gauge steel than most
          regulated USTs;
tend
     •    Although most exempt tank systems store heating (87 percent, based
          on our population estimates) most regulated USTs store motor fuels;

     •    Although exempt tank systems use suction pumps, about one-half of
          the regulated USTs (including most of the retail motor fuel
          facilities) use pressurized pumps.  The use of suction pumps results
          in negative pressure on the feed lines, and, if a leak occurs, air
          and water are drawn in, instead of product being pumped out; and

     •    Effective methods of leak prevention and detection are less commonly
          an integral part of exempt nonresidential tank systems, compared to
          regulated USTs and are seldom a part of small exempt residential or
          farm tank systems.                                                  -

Extent of and Potential for Releases

     The  annual rate of reported releases from exempt tank systems has
increased significantly over the last 17 years.  For example, the number of
reported  releases from exempt tank systems in just three states in a recent 2-
year period (1985-1987) exceeds the number of reported incidents in EPA's
National  Data Base for the entire nation over the previous 15 years.

                                     ES-3
                                                                                  1.

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     Documented data,  case, histories,  and other information collected during
 this investigation lead to the following observations:

     •    Reports  of releases from regulated USTs are more common than reports
          of releases  from exempt tank systems.   Differences  in release
          detection and reporting may account for some  of this disparity.
ซ                                                                            *.
     •    Reports  of releases from exempt tank systems  most frequently occur
          in the Northeast and involve release of fuel  oil No. 2.

     •    Nearly 80 percent of reported releases from exempt  tank systems are
          from nonresident ial tank systems,  even though this  sector comprises
          only 25  percent of the exempt tank systems that are subject to this
          study.   Differences in release detection and  reporting may account
          for some of  this disparity.

     •    Some exempt  tank system releases have occurred over a long time and
          the effects  from some releases have persisted in the environment for
          years despite attempted corrective actions.

     •    The material of construction for exempt nonresident ial tank systems
          is similar to regulated USTs-.  Exempt residential tank systems,
          however,  tend to be made of thinner and lighter-gauge steel.
      •     The age,  cause of relep.^,  and reported release  quantities are
           similar for exempt tank systems and regulated USTs.

      As  a result of their similar characteristics,  the  potential for exempt
 tank systems  and regulated USTs to leak is likely to be similar if they are
 not protected against corrosion.

 Potential Inpacts to Hunan Health

      Exempt heating oil and motor fuel tank systems are used to store a
 variety  of petroleum products,- including gasoline and diesel fuel (motor
 fuels),  and fuel oils Nos.  1,  2,  4,  5, and 6 (heating oils).  With the
 exception of  gasoline, the toxicities of these fuels have  not been well
 studied  and only limited information regarding the fuels as mixtures is
 available. Gasoline, which has been the subject of extensive study under
 RCRA1 s Subtitle I regulatory program, is already classified as a probable
 human carcinogen.  Consequently,  the discussion of potential impacts to human
 health in this study focuses primarily on heating oils, the petroleum products
 stored most frequently in exempt tank systems.                                "

      All of the products stored in exempt heating oil and  motor fuel tanks
 contain  noncarcinogenic substances that can cause adverse  health effects.  In
 addition, some of the products contain known or probable carcinogens; however,
 the exact concentrations of the hazardous substances present in these products
 are unknown.   The principal routes of human exposure to releases are through
 contamination of air, soil, surface water, and,  most significantly, ground
 water.   Although the exact level of risk posed by releases of these products

                                      ES-4

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is difficult to assess, relative risks can be assessed based on the toxicity
of the product and its constituents,  and .the likelihood of the products to
contaminate soil, ground water, and air.

     •    Contaminated ground water is the most likely route of human exposure
          to products released from exempt tank systems.  Consumption of
          ground water with low levels of contaminants may continue for long
          periods of time and thus represents the most significant threat to v
          human health.  High levels of contamination are less of a problem
          because people are less likely to drink water that has a bad taste
          or smell.

     •    Gasoline is the most studied fuel stored in exempt tank systems.
          Gasoline is likely to travel faster in the soil than other products
          stored in exempt tanks systems and is a probable human carcinogen.

     •    Of the heating oils, the middle distillates, such as fuel oil No. 2.
          probably pose the greatest threat to human health.  These products
          are slightly less mobile than gasoline, but are still likely to
          contaminate ground water.  In addition, low levels of probable
          carcinogens have been detected in fuel oil No. 2.  The middle
          distillates also contain other substances known to have adverse
          health effects.•

     ซ    Residual fuels, suchas fuel oil No. 6.probably posethe smallest
   •*•*     threat to human health, but this threat may still be significant.
          E'/en though fuel oil No. 6 c-jntains relatively high levels of
          cancer-causing substances, it can have such a high viscosity
          (resistance to flow) that it is unlikely to reach ground water in
          large quantities.  However, under certain conditions, such as fuel
          oil No. 6 released near a sewer line or into fractured bedrock,
          large amounts of contamination have occurred.  Furthermore, although
          residual fuels are not as mobile as the middle distillates, they axe
          difficult to clean up after a release and are likely to persist in
          the environment longer than other fuels.

State and Local Regulation of Exenpt Tank Systems

     During February 1988, EPA examined statutes and regulations from 34
states  to determine the current level of regulation of exempt heating oil and
motor fuel tank systems by states (the remaining 16 states did not have UST
statutes available for review).  This review revealed that at least 21 states
currently consider exempt tank systems to be a problem and, have included them
to some extent in their regulatory framework.  Of the 34 states reviewed:     ?

     •    Twenty states have some regulations for exempt heating oil tank
          systems (panel 1 of Exhibit 5-1);

     •    Ten states have some regulations for exempt motor fuel tank systems
          (panel 2 of Exhibit 5-1);
                                     ES-5

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     •    Six .states have some regulations for all exempt tank systems (panel
          3 of Exhibit 5-1); and
  •ป
     •    Thirteen states have no regulations for exempt heating oil and motor
          fuel tank systems (panel 4 of Exhibit 5-1).

     Although some states require only that owners and operators of exempt
tank systems report and clean up releases, others impose a variety of
technical standards (such as material of construction and leak detection).
Many of the state regulations governing exempt heating oil tank systems,
however, cover only those tank systems with a capacity equal to or greater
than a specified size, most commonly 1,100 gallons.

     State regulation of exempt tank systems was generally more extensive in
those states where the greatest number of exempt tank systems are located.
For example, all of the states in the Northeast, except Pennsylvania and
Delaware, have some regulations regarding exempt heating oil tank systems
(exempt heating oil tank systems located in the Northeast comprise almost 50
percent of all exempt tank systems).
                                     ES-6

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                      1.  BACKGROUND AND STDDY APPROACH
     Subtitle I of the Resource and Conversation Act (RCRA) requires the U.S.
Environmental Protection Agency to develop a national program for regulation
of underground storage tanks (USTs).   Subtitle I excludes from regulation nine
types of underground tank systems including two that are the focus of this \
study:

     •    Tank systems used for storing heating oil for consumptive use on the
          premises where stored; and

     •    Farm or residential tank systems of 1,100 gallons or less capacity
          used for storing motor fuel for noncommercial purposes. ป*

This study was undertaken to comply with Section 9009 (d) and (e) of RCRA,
which requires EPA to study the tanks listed above and to report to the
President and Congress whether these underground tank systems (hereafter,
referred to as exempt tank systems) should be subject to the provisions of
Subtitle I.

     This report is divided into five sections.  The following sections of
this study address the questions below:

Section 2.  Description of Exempt Heating OS1 and Motor Fuel Tank Systems

     •    What is the size of the population of exempt tank systems?

     •    What is the geographic distribution of that population?

     •    What characteristics of exempt tank systems affect their likelihood
          to leak?
     ^ The following structures or tank systems are also excluded from
regulation under Subtitle I, but are not addressed in this study:  septic
tanks; pipeline facilities regulated under certain other federal and state
laws; surface impoundments, pits, ponds, or lagoons; storm water or wastewater
collection systems; flow-through process tanks; liquid traps or associated          ซ
gathering lines directly related to oil or gas production and gathering             '
operations; or storage tanks situated on or above the surface of the floor in
underground area:;.  Subtitle I exempts these tanks by excluding them from the *
definition of underground storage tanks (USTs).  When used in this report, the
term "exempt tank system" refers only to exempt heating oil and motor fuel
tanks, while the term "regulated UST" refers only to underground storage tanks
regulated under Subtitle I.

     2 Definitions for underground storage tank, regulated substances, tanks,
tank systems, and exempt heating oil and motor fuel tank systems are provided
in Appendix E.
                                     1-1

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Section 3.  Extent of Releases from Exempt Heating Oil and Motor Fuel Tank
            Systems

     •    To what extent do exempt tank systems presently leak?

     •    What is the potential for releases from exempt tank systems?

Section 4.  Potential Impacts on Human Health of Products Released from Exempt
            Heating Oil and Motor Fuel Tank Systems

     •    What adverse health effects have been associated with exposure to .
          products stored in exempt tank systems?

     •    How are released products transported through the environment?

     •    What are the potential health risks associated with exposures to
          products released from exempt tank systems?

Section 5.  State and Local Regulation of Exempt Heating Oil and Motor Fuel
            Tank Systems

     •    To what extent do state and local governments currently regulate
          exempt tank systems?

In addressing these questions, this study compares its findings with similar
information regarding USTs regulated under Subt4 -:le I.

     The exempt tank systems addressed in this study are divided into two
major types: motor fuel tank systems and heating fuel tank systems.  Exempt
motor fuel tank systems are subdivided into tank systems located at farms and
those located at residential buildings.  Exempt heating oil tank systems are
subdivided into tank systems located at farms, at residences, and at
nonresidential facilities.  Residential facilities include such residential
units as apartment complexes, condominiums, townhouses, and single-family
homes.  Nonresidential facilities include tank systems located at commercial,
institutional, government, manufacturing, and military facilities.  The
distinction between motor fuels and heating oils and the breakdown of sectors
among farms, residences, and nonresidential facilities in this study
corresponds with the language of the statutory exemption.

     This study was conducted in three stages.  First, EPA assessed the size,
geographic location, and other characteristics of the population of exempt
tank systems, including the extent of known releases from these tanks, using
standard survey/research te ihniques.  Second, this information was reviewed by"
federal and state government officials, and underground storage tank systems
industry representatives.  Third, the information and comments received from
these individuals were assessed, and additional analyses were performed on
data that was obtained from underground tank systems and petroleum industry
representatives and government officials, to address comments made regarding:

     •    Size of the population of exempt tank systems and how it was
          estimated;
                                     1-2

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     •    Differences among use sectors .and among various fuels stored in
          exempt tank systems^;-;/      '•••:•'-•<•.

     m    Potential for exempt tank,systems to leak, including the principal
          causes;

     •    Fate and transport of released product in the environment; and

     •    Potential hazards to human health and the environment posed by
          released products.

     This study relies mainly on existing data.  Additional information was
obtained from states and other readily available sources, but no new surveys
were conducted.  Some of the additional information obtained was useful in the
analyses only if some reasonable assumptions were made.  To the extent
possible, underground tank systems and petroleum experts from both industry
and government were contacted regarding the validity of the assumptions used.
Each section of this document includes a brief description of the methods and
assumptions used.  The specific sources of data and analytic procedures used
are described in the Appendices.
                                     1-3

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                          2.   DESCRIPTION OF EXEMPT
                   HEATING OIL AND MOTOR FUEL TANK SYSTEMS


     This section presents information on the universe of exempt tank
systems,^ including the size of the population (Section 2.1);  geographic
location  (Section ?.2); technical characteristics (Section 2.3); current
management practices (Section 2.4); and summary findings (Section 2.5).

2.1  SIZE OF THE POPULATION

     The estimated total population of exempt heating oil and motor fuel tank
systems in the United States is 3.1 million, almost twice the number of USTs
currently regulated under Subtitle I (Exhibit 2-1).   The exempt tank systems
population consists of 2.7 million tanks storing heating oil and 0.4 million
tanks storing motor fuel.  Estimates of the size of the population for the
three sectors of exempt heating oil tank systems and two sectors of exempt
motor fuel tank systems are presented in Sections 2.1.1 and 2.1.2,
respectively.

     The precision and accuracy of these estimates could not be defined
quantitatively.  Data quality obj ectives were set at the beginning of this
study assuming that if tank system estimates are within a factor of two of the
true population size, the errors in the estimates would no"  significantly
affect the regulatory decisions So be made as a result of I  lis report.  A
discussion of the sources of data, the methodology used, an  an assessment of
the factors potentially affecting the accuracy of the estimates of the
population size is presented in Sections A.I and A.2 of Appendix A.

2.1.1  Exempt Heating Oil Tank Systems

Residential Heating Oil Sector

     The size of the exempt residential heating oil tank system population is
estimated to be 1.9 million tank systems, which include an estimated 1.6
million single-family residential tank systems and 0.3 million multiple-family
tank systems.  These numbers were derived from estimates of housing units
using heating oil and the estimated probability that these heating oil tanks
are buried underground.  U.S. Census data were used to estimate the number of      *
housing units.  The probability that heating oil tanks are buried underground
was derived from contacts with industry representatives (see Exhibit A-4 of
Appendix A; and PMAA 1987).  Additional information on the >e estimates is
provided in Section A.1.1 of Appendix A.
     3  An exempt tank system includes a single exempt tank and its associated
piping.  Further elaboration of this definition and other definitions,
including heating oil and motor fuel tank systems, are found in Appendix E.
                                     2-1

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                                    Exhibit 2-1

             Population Size of Exempt and Regulated USTs
    Regulated and Exempt USTs
                                                       Exempt USTs
                                                                      Farm
                                                                    Heating Oil
                                                                    0.04 million
s. - ^ซVx
p Exempt Heating Oil
•& & Motor Fuel USTs
    3.1 million
     Subtitle I
       USTs
     1.7 million
                                                                              Farm
                                                                            Motor Fuel
                                                                            0.3 million
                                                                                Residential
                                                                                Motor Fuel
                                                                                0.1 million
Source: See appendix A for sources and derivations.
                                   2-2

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Farm Heating Oil Sector

     The estimated size of the exempt underground farm heating oil tank system
population is 0.04 million tanks, as reported by the 1985 Farm Costs and
Returns Survey (U.S. Department of Agriculture,  unpublished data).  Some of
these tank systems could also be included in the estimate of residential
heating oil units in the U.S. Census, because owners and operators could have
reported their tank systems as both residential and farm tanks.  The effect of
this potential overlap on the national estimate of the entire exempt tank
system population is minimal, because the entire farm heating oil sector
comprises only 1 percent of the total estimated number of exempt tanks
(Exhibit 2-1). (Additional information on this estimate appears in Section
A. 1.2 of Appendix A. )

Nonresidential Heating Oil Sector4

     There are an estimated 0.8 million exempt nonresidential heating oil tank
systems.  This number was determined by adding estimates for three individual
subsectors (commercial, institutional, and government facilities;
manufacturing facilities; and military facilities).  Estimates of this exempt
tank system population and the general methods used to derive the estimates .
for each of the subsectors are provided below.  (Additional information on
these estimates is provided in Section A. 1.3 of Appendix A.)
     Coimercial . Institutional , arul CovernngTit; Tank Syg*-ซ*'ปg -   There are' an
estimated 0.54 million exempt heating oil tank systems in the comir?rcial,
institutional, and government subsector.  This number was estimated based on
the number of heating oil tanks (including both aboveground and underground
tanks) identified in the Non-Residential Buildings Energy Consumption Survey
(U .S . Department of Energy 1985).  This survey includes estimates of the
number of buildings with heating oil as an energy source, the number' of
heating oil tanks, and the total tank capacity.  To estimate the population of
this subsector that is buried underground, the probability of a heating oil
tank being buried, based on both tank and building size, was multiplied by the
estimated number of heating oil tanks.  The probability that a tank is buried
underground was derived from contacts with industry representatives (see
Exhibit A-4 of Appendix A; and PMAA 1987) .

     Manufacturing Tank Systems.  There are an estimated 0.19 million exempt
heating oil tank systems located at manufacturing facilities.  There were no
Census or survey data available for directly estimating the number of exempt        \
manufacturing heating oil tank systems; therefore, the estimated total storage
capacity for heating oils stored for consumptive use at manufacturing
facilities (obtained from the National Petroleum Council 1984) was divided by I..
an estimate of the average tank capacity of manufacturing heating oil tanks
(including both aboveground and underground tanks) to determine the number of
manufacturing heating oil tanks.  The number of tanks that are buried
     ^ Nonresidential exempt heating oil tanks include tanks located at
commercial,  institutional, government, manufacturing, and military facilities
(but not farms).
                                     2-3

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underground was then estimated by multiplying the number of storage tanks by
the percentage assumed to be buried (see Exhibit A-4 of Appendix A; and PMAA
1987).

     Military Tank Systpns.   There are an estimated 0.06 million exempt
heating oil tank systems owned by the military services, according to
information obtained from the four military services.  An estimated 0.042
million heating oil tank systems are used to heat military residential
facilities.  The number of exempt tank systems used to heat nonresidential
buildings could not be directly estimated.  However, according to the military
services, three-quarters of all military heating fuel tank systems are
associated with housing, which implies that there are an additional 0.014
million tanks for heating nonresidential military buildings.  Thus, the total
number of exempt tank systems owned by the military was estimated to be 0.056
million tank systems (or 0.06 million after rounding).  A breakdown of the
number of exempt residential heating oil tank systems reported by each
military service is provided in Section A. 1.3 of Appendix A.

2.1.2  Exenpt Motor Fuel Tank Systems

Fan* Motor Fuel Sector

     There are an estimated 0.3 million exempt farm motor fuel tank systems.
The number of these tank systems has been estimated by two separate surveys:
the 1985 Farm Costs and Returns Survey (U.S. Department of Agriculture,
unpublished data) and the Mo1'^r Fuels Storage Tanks Survey (USEPA 1986a).  The
1985 Farm Costs and Returns x< ixvey estimated a total of 0.37 million i'^rm
motor fuel tank systems.  Th; Motor Fuels Storage Tanks survey estimated a
total of 0.16 million of these tank sys terns.  The average of these two
estimates -- 0.26 million tanks -- was selected as the best estimate of the
number of farm motor fuel tank systems.  (Additional information on this
estimate appears in Section A.2.1 of Appendix A.)

Residential Motor Fuel Sector

     There are an estimated 0.2 million exempt residential motor fuel tank
systems.  No published Census or survey data exists from which estimates of  .
the number of exempt residential motor fuel tank systems could be directly  .
made.  Three states (California, Maine, and Wisconsin), however, require
registration of all exempt motor fuel tank systems and reported a total of
12,409 exempt motor fuel tank systems in their UST notification data bases.
The mean of the ratio of the number of exempt motor fuel tank systems to the
number of housing units for each state was used to extrapolate the number of
exempt residential motor fuel tank systems nationwide.  This ratio was
multiplied by the estimated number of housing units in the U.S. Census.  This
extrapolation is described in Section A.2.2 of Appendix A.

2.2  GEOGRAPHIC LOCATION

     The geographic location of the exempt tank systems in the three heating
oil sectors and the farm motor fuel sector was determined using the same
methodology that was employed for the national population estimate; however,
                                     2-4

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 regional data were  substituted for national population aggregate data  in the
 calculations presented  in Appendix A.  The four geographic  regions  depicted in
 Exhibit 2-2 represent the regional classifications used by  the U.S.  Census.
 The  geographic  location of the final sector, exempt residential motor  fuel
 tank systems, could not be properly determined, because the national estimate
 is based on data from just three states.

      Exhibit 2-2 illustrates the regional location of exempt tank systems,  v
•Heating oil. tank systems, especially residential heating oil tank systems are
 concentrated in the Northeast; relatively few are located in the West  (Exhibit
 2-3).  Farm heating oil tank systems are more uniformly distributed throughout
 the  country.  Exempt farm motor fuel tank systems are concentrated  in  the
 North Central and West; the Northeast contains the fewest of these  tank
 systems.

 2.3   TECHNICAL  CHARACTERISTICS

      Five  categories of technical characteristics for exempt tank systems are
 described  in this section:  (1) system description; (2) construction material;
 (3)  age;  (4) capacity;  and (5) contents.  Data on the first and fifth
 categories were obtained from interviews with representatives of the
 underground storage tank and petroleum industries.   Data on the second,
 third, and fourth categories were obtained from the state UST notification
 data bases for  California, Montana, and Maine** and from interviews  with UST
 program officials in Connecticut, Kansas, Massachusetts., Minnesota,  and North
 Carolina  (CDEP  1986; KDHE 1986; MDEQE 1986; MPCA 1986; and  NCDNRCD  1986),   The
 number of  tank  systems  registered in the, California, Montana, and Maine s;.ate
 notification data bases at the time of this study is presented in Section A. 3
 of Appendix A.

 2.3.1 Systen Description

      This  section describes the major components of typical exempt  tank
 systems based on information obtained from underground storage tank and
 petroleum  industry  representatives.  A detailed description is provided for
 typical exempt  residential or farm heating oil tank systems and these  systems
 are  compared to other exempt tank systems and regulated USTs.
      ->  The information was  obtained during spring,  1988,  from discussions
 between Midwest Research Institute  and representatives  of  Besche Oil (Waldorf,:
 MD),  Bridgeport Testing Lab  Chemicals (Bridgeport, CT),  Buffalo Tank
 (Baltimore, MD), T.W.  Perry  (Gaithersburg,  MD),  Shreve  Fuel (Arlington,  VA),
 and Southern Maryland Oil (La Plata,  MD).

      ^ These three states require registration of both  exempt tank systems and
 regulated USTs.  Although some other states have similar requirements,  data
 were not available.
                                      2-5

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                             Exhibit 2-2
       Geographic Concentration of Exempt Heating Oil and
                    Motor Fuel Tank Systems'
                                                 54%
* Totals for the West include Alaska and Hawaii.
                              2-6

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                                        Exhibit 2-.
      Geographic Concentration of Exempt Heating Oil and Motor Fuel Tank
                               Systems by Use Sectora
    Residential Heating Oil Tank Systems (61 %)
Farm Heating Oil Tank Systems (1'
                               36%
                   '23%
                      South
                                              Nonresidentiaf Heating Oil Tank
                                                     Systems (25%)*  ,   f-
                                                  Farm Motor Fuel Tank Systems |IO%)
                                                                    35%
                                                          37%
See Appendix A for sources and derivations.
 a Totals for West include Alaska and Hawaii.
 b Numbers in parentheses are the percentage that each use sector contributes to the universe of exempt
  heating oil and motor fuel tank systems.
                                          2-7

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Residential and Fara Heating Oil Tank Systens

     Residential and Ifarm heating oil tank systems are commonly designed by
the fuel oil supplier to meet customer needs and local regulatory
requirements.  Tanks are usually installed close to the residence (i.e.,
within 6 feet) and are covered with approximately two feet of soil.  Some
contractors use select backfill materials, such as sand, but most simply
refill the excavation with the native soil.

     A typical residential or farm heating oil system includes a bare steel
tank (usually less than 1,000 gallons in capacity), a vent pipe, a fill pipe,
and a feed line to the burner (furnace).  Host systems also have a return line
from the burner to the tank to return unused oil.  Most new installations use
1/4- or 3/8-inch diameter, soft, rolled copper piping for the feed and return
lines in order to minimize the number of joints needed.  Older systems
commonly use 1/2-inch diameter carbon steel piping.  The fill and vent lines
are generally made of galvanized or coated and wrapped carbon steel with a
diameter of 1 1/4 or 1 1/2 inches.  A diagram of a typical residential or farm
heating oil tank system is shown in Exhibit 2-4.

     Residential and farm heating oil tank systems usually use a suction pump
located at the burner to lift or pull heating oil No. 2 from the tank to the
burner.  This results in a low (5-10 PSIG) negative pressure on the feed line
and a low (5-10 PSIG) positive pressure on the return line.  If the feed line
develops a leak* it will tend to draw air or water into the system, rather
than forcing bracing oil out of the pipe.  The presence of excess air or water
in tiie feed line can result in the fouling of th& burner, a condition that can
signal to tank owners that they have a problem with their tank system.  A
nontight return line, on the other hand, will tend to force unused oil out of
the pipe under low pressure; such a leak can be difficult to detect.

     Heating oils and motor fuels are usually delivered by 2,500 to 3,000-
gallon trucks.  Product is commonly delivered from the truck to the tank
through a 1 1/4-inch industrial hose with a "Scully" nozzle on the end that
attaches to the tank's fill nozzle.  The nozzle couples tightly with the fill
pipe, but is capable of popping free if back pressure is encountered.
Alternatively, a "tight fit" nozzle, which locks to the fill pipe and will not
release in the event of back pressure, is sometimes used.  A "tight fit"
nozzle can overpressure and rupture a tank if the vent line is clogged.

     Vent piping, which allows the tank to breathe, allows air to escape from
the tank when it is being filled and to enter the tank while oil is being
withdrawn.  In some systems, a device referred to as a "whistler" is installed*
in the vent line to prevent overfilling (refer to Exhibit 2-4).  As air is
forced out of the tank during the filling operation, the unit produces a
whistling noise.  When the fluid reaches the device, the noise ceases and the
delivery is stopped.  Heating oil distributors report that spills from
overfilling are small (less than one-gallon) if a Scully nozzle is used and a
whistler is present in the vent line.
                                     2-8

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   Typical Exempt Residential or Farm Heating Oil Tank System
                                                             BDltar
                                                             Pump LNU ON
                                                             From TMik
Source:  Midwes.c Research Institute, Spring 1988.
                                  2-9

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Nonresidential Heating Oil Tank Systens

      The  components  for small nonresident ial heating oil  systems are very
similar to  those  of  residential and farm heating oil systems, but become more
complex for larger facilities.  Medium-sized nonresidential facilities differ
from residential  and farm heating oil tank systems mostly by using larger
tanks and piping.  Large facilities (such as industrial operations,
manufacturing plants,  and military bases) may use large tanks (5,000 to
'100,000 gallons)  or  multiple tank systems manifolded together, and tend to
have larger (2- to 4-inch diameter),  more complex,  and longer piping that
operates  under higher pressure (pressures up to 200 PSIG  are not uncommon). .A
diagram of  one possible large nonresidential heating oil  tank system is shown
in Exhibit  2-5.

      It is  often  more economical for larger heating oil systems to use
residual  heating  oils (a lower grade of heating oil than  fuel oil No. 2,
including fuel oil Nos. 5 and 6 and most blends of fuel oil No. 4).  The use
of residual fuels requires some specialized tank system equipment, including
differences in: (1)  burner types for atomizing the fuel prior to its burning
and (2) tank heaters and pumps that,  depending on the climate and
characteristics of the particular fuel used,  improve the  ability of the fuel
to flow within the tank system.

Residential and Farm Motor Fuel Tank Systens
             residential and farm motor fuel systems have  a capacity of 1,100
 gallons or less  and are similar to smaller heating oil  systems.  Most of these
 tank systems have simila.  components to residential and farm heating oil
 systems.   Piping systems are electrically grounded to prevent  fires, and
 whistlers are  not used in  the vent lines because of potential  fire and
 explosion hazards.  Most jurisdictions require some type  of tank permit from
 the local fire department.   A typical residential or farm motor fuel system is
 shown in Exhibit 2-6.                                                     ;

 Conparisons Between Exenpt Tank Systens and Regulated USTs

        Exempt  tank systems have many characteristics in common with the
 regulated USTs,  as well as some significant differences.   Similarities include
 some essential system components -- the tank,  piping, and a pump.  Differences
 include the size of the tank and pipes,  type of pump, and operating
 characteristics.  This discussion highlights some of the  key similarities and
 differences between these  two populations.

        Exempt  resident! 1  and farm tank systems are generally  much smaller and
 have thinner -walled tanks,  particularly for heating oil tank systems, than
 either exempt  nonresidential tank systems or regulated  USTs.   Thinner-walled
 tanks appear to  be more susceptible to external corrosion and  tank leakage.
 In contrast, the common sizes of tanks and piping used  for exempt
 nonresidential tank systems are similar to those commonly used by regulated
 USTs.
                                     2-10

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                              ซ.—r •'
                             ,-.:*•*•&'-
                                 Exhibit 2-5
   One Possible Large Exempt Nonresidential Heating Oil Tank System
                                                   Sleng* Tank
Source:  Midwest Research Institute, Spring 1988.
                                      2-11

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                              Exhibit 2-6

  Typical Exempt Residential or Farm Motor Fuel Tank System
                                                          man Hot *
                                                          Flam* Amttor
                                                      Supply Lin*
                                                      Otlvซnli*cl 8t**l
                                              •Vint Lin*
                                  8toปB* TMk
Source:  Midwest Research Institute, Spring 1988.
                               2-12

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     Exempt residential and farm tank systems typically have fewer and shorter
pipes that are less complex than other exempt tank systems or regulated USTs.
Regulated USTs, as represented by a motor fuel retail facility,  tend to have a
complex system of pipes to manifold multiple tanks together.

     Regulated USTs most frequently use pressure pumps, whereas  exempt tank
systems (especially residential, farm, and small nonresidential  tank systems)
use suction pumps. .The use of pressure pumps results in positive pressures on
motor fuels in the piping, which increase the rate of product released if
structural failure, loose couplings, or corrosion breakthrough occurs.  The
use of suction pumps, particularly for residential and farm heating oil tank
systems, results in a negative pressure in the feed line and a small positive
pressure in the return line.  If structural failure, loose couplings, or
corrosion occurs on the feed line of a heating oil tank system,  air or water
tends to be drawn in, rather than stored product being forced out.  The
positive pressure on the return line of exempt tank systems would typically be
less than that of regulated USTs.  This lower pressure, along with heating
oil's greater resistance to flow compared to gasoline, reduces the rate at
which stored product is released from exempt tank systems.

     Finally, regulated USTs more often have some type of built-in leak
detection than do exempt tank systems, especially residential and farm tank
systems.

2.3.2  Construction Material

     Most exempt tank systems are constructed of steel (Exhibit  2-7).  More
exempt residential and farm heating oil and motor fuel t nk systems are made
of steel than are exempt nonresidential heating oil tank systems, according to
information obtained from California and Maine.  A high proportion of steel
tanks was also reported by UST program officials from Connecticut, Kansas,
Massachusetts, Minnesota, and North Carolina, who estimated that over 95
percent of exempt tank systems in their states were constructed  of steel.  In
comparison, it is estimated that 89 percent of USTs regulated under Subtitle I
are made of steel (ICF 1988a).

     In California, fiberglass-reinforced plastic (FRP) tank systems were more
frequently used than in Maine or Montana, particularly for USTs  regulated
under Subtitle I.  The higher proportion of FRP tank systems in  California may
be a result of relatively stringent state regulation of both federally
regulated USTs and exempt tank systems compared to other states  (see Section
5).

2.3.3  Age                                                                    :

     Approximately one-third to one-half of exempt tank systems  in California,
Maine, and Montana are over 16 years old (Exhibit 2-8).  Exempt  nonresidential
tank systems are older than exempt residential or farm tank systems in
California and Maine.
                                     2-13

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                                 EXHIBIT 2-7

                     COMPARISON OF CONSTRUCTION MATERIAL
                  FOR EXEMPT TANK SYSTEMS AND REGULATED USTs

                     (Percent of Registered Tank Systems)
                         Exempt Tank Systems
                                          Regulated USTs
                      Heatin  Oil
             Farm or Residential  Nonres ident ial
                              Motor Fuel
California:

     Steel

     FRP

     Other
87

 0

13
                                      78

                                      10

                                      12
               87

                1

               12
81

10

 9
Maine:

     Ste4l

     FRP

     Other
                    99
92

 8
                                 99
95

 5
Montana:

     Steel
          •99-

          --0-
                                                     99
                             97
Source:  State UST Notification Data Bases from:  California State Water
Resources Control Board, Dec. 1986; Maine Dept. of Environmental Protection,
Dec. 1986; and Montana Dept. of Health and Environmental Science, March 1987.
                                     2-14

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                                 EXHIBIT 2-8

         COMPARISON OF AGE OF EXEMPT TANK SYSTEMS AND REGULATED USTs

                     (Percent of Registered Tank Systems)

Tank Age
( Years')
<5
6-10
11-15
16-20
>20
Exempt
Heating Oilb
Farm or Residential
10
27
27
12
24
Tank Svs terns

Nonres idential
8
22
18
12
40

Motor Fuel

10
27
25
14
24
Regulated USTsa


16
21
21
18
24
Totals
100
100
100
100
Source:  State UST Notification Data Bases from:  California State Water
Resources Control Board, Dec. 1986; Maine Dept. of Environmental Protection,
Dec. 1986; and Montana Dept. of Health and Environmental Science, March 1987.
     a Data on regulated USTs in the Regulatory Impact Analysis are slightly,
but not significantly different (IGF 1988a).

     b Data for heating oil tanks includes data only from California and
Maine.  The Montana data base did not contain sufficient data on facility type
to analyze by use sectors.
                                     2-15

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     The age of exempt residential and farm tank systems is very similar to
the age of USTs regulated under Subtitle I in these states (Exhibit 2-4).
However, in California and Maine there is a larger proportion of exempt
nonresidential heating oil tank systems over 20 years old compared to USTs
regulated under Subtitle I.

2.3.4  Capacity

     Of the exempt farm and residential heating oil tank systems located in
California or Maine, 88 percent had a capacity less than or equal to 1,100
gallons (Exhibit 2-9).  Exempt motor fuel tank systems, by statutory
definition, must all be under 1,100 gallons in capacity.  In contrast, the
capacity of nonresidential heating oil tank systems in these states is
generally much larger and highly variable.

     Exempt residential and farm tank systems storing either heating oil or
motor fuel are generally smaller than USTs regulated under Subtitle I.  The
size distribution of nonresidential heating oil tank systems in California and
Maine, however, is similar to that of USTs regulated under Subtitle I (Exhibit
2-9).

2.3.5  Contents

     Exempt motor fuel tank systems most commonly contain gasoline or diesel
fuel.  Exempt residential and farm heating tank systems generally contain fuel
oil Nos. 1 or 2, although some of the large residential facilities,
particularly large multiple-family dwellings, use'fuel oil Nos. 4, 5, or 6.
(For purposes of this report, we have combined information regarding kerosene
and fuel oil No. 1, as appropriate, because of the similar specifications of
these products.)  Exempt nonresidential heating oil tank systems contain a
variety of heating oils, from fuel oil No. 1 to No. 6.  The particular heating
oil stored in tanks is determined by the type of heating equipment present at
each facility.  Fuel oil No. 2 is used most prevalently and is consumed in :
facilities of all sizes.  In contrast, the use of residual fuels, such as fuel
oils Nos. 5 and 6, is usually limited to large facilities (e.g., schools,
shopping centers, or manufacturing plants), because burning these fuels
requires special equipment that is generally cost effective only in very large
facilities.
2.4  CURRENT MANAGEMENT PRACTICES

     Information was gathered from interviews with state and local government
officials and UST industry organizations to provide an overview of the leak
prevention and detection methods currently practiced by exempt tank system
owners and operators.  Leak prevention and detection methods are less
frequently practiced at exempt tank systems than at regulated USTs.
                                     2-16

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                                 EXHIBIT. 2-9
COMPARISON OF CAPACITY FOR EXEMPT TANK SYSTEMS AND REGULATED USTs
(Percent of Registered Tank Systems)

Tank
Capacity
(gallons)
<500
500-999
1000-1100
1101-4999
5000-9999
> 10,000
Total
-V
Exempt Tank Systems Regulated USTs
Heating Oila Motor Fuel
Farm or Residential Nonres ident ial
27 6 16 4
43 18 54 12
18 19 30 15
8 20 -- 29
2 11 --- 19
2 26 -- 21
100 100 100 100
Source:  State UST Notification Data Bases from: California State Water
Resources Control Board, Dec. 1986; Maine Dept. of Environmental Protection,
Dec. 1986; and Montana Dept. of Health and Environmental Science, March 1987.
     a Data for heating oil tanks includes data only from California and
Maine.  Montana data base did not contain sufficient data on facility type to
identify use sectors.
                                     2-17

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2.4.1  Leak Prevention

     Government officials from Connecticut, Kansas, Maine, Massachusetts,
Minnesota, and North Carolina expressed the opinion that over 95 percent of
exempt tank systems are made of bare steel and lack any protection against
corrosion.  Analyses of the notification data bases of Maine, Montana, and
California (Section 2.3.2) confirm these findings.  Furthermore, farm and   ••  '
residential tank systems are less likely to be made of noncorrodible raterials
or have cathodic protection than are nonresidential tank systems or USTs
regulated under Subtitle I.  According to representatives of the Steel Tank .
Institute, exempt farm and residential tank system owners are more likely to
have lower quality tanks compared to other exempt tank system owners (STI
1986).  Smaller tanks are more likely to be made with thinner steel, which may
corrode faster than larger tanks.  Furthermore, leak prevention measures are
more likely to be used in the nonresident ial heating fuel sectors than the
farm and residential sectors (see the state notification data bases for
California, Maine, and Montana).

     Poor quality installation of tank systems and their piping was cited as
another significant source of exempt tank system failures by UST officials
from Connecticut, Kansas, and Maine.  A group of Petroleum Equipment Institute
members and installers noted that many installers are not using appropriate
equipment or materials (USEPA 1987).  Kansas officials report that farmers
often have access to the heavy equipment needed to install an underground tank
system and may incorrectly install their own systems.  These installations
often use native soils as backfill materials, a practice that increases the
rate of exterior tank corrosion.  Some farmers use USTs discarded by regulated
UST owners, and this recycling of tanks occurs without proper inspection or.'
tightness testing (KDHE 1986).  Maine and Connecticut officials reported
finding 275-gallon tanks installed underground (IGF 1988b).  These tanks,
which are not designed for underground use, have thin walls and are vulnerable
to corrosion.

2.4.2  Leak Detection

     Discussions with government officials indicate that exempt tank system
owners and operators generally do not have effective release detection
equipment and do not employ adequate operating practices (ICF 1988b).  Except
for areas covered by specific state or local regulations, exempt tank system
owners are less likely to employ leak detection equipment or practices than
owners of regulated USTs.  Nonresidential tank systems are more likely to have
leak detection equipment than residential or farm tank systems.  Residential
tank systems serving multiple-family complexes, however, may more closely
resemble nonresidential USTs than single-family residential tank systems.
Some nonresidential facilities with monitoring equipment for their regulated
USTs may also monitor their exempt tank systems.  Many owners of larger
commercial or manufacturing tank systems storing fuel oil Nos. 4 or 6 employ
operating engineers to monitor the tank systems (Oil Heat Task Force 1987).
Sensitivity to public scrutiny and liability concerns, particularly for
facilities operated for-profit by moderate- to large-size corporations, may
also encourage the use of leak detection equipment at these nonresidential
                                     2-18

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sites.  In contrast, Maryland officials expressed concern that schools and
churches frequently lack the financial resources and technical training to
properly operate and maintain their heating oil tank systems (IGF 1988c).

     Exempt farm and residential tank systems owners generally employ minimal,
if any, leak detection.  Few owners of exempt residential and farm tank
systems practice inventory control measures using gauges or dip sticks;
however, the Petroleum Marketers Association of America (FMAA) stated that  v
water leaking into a perforated heating oil tank fouls the burner,  indicates a
leak, and reduces the need for leak detection measures (FMAA 1987).,  Water
will enter a tank only if the tank is situated in the water table.   In
addition to the effect of water, FMAA stated that heating oil tank systems do
have an effective inventory control program that is commonly run by petroleum
distributors.  These distributors are reported to employ a "degree day"
monitoring program that uses past fuel consumption rates for each facility and
recent temperatures to estimate fuel consumption.  This information is used by
distributors to indicate when more fuel oil needs to be delivered.   Thus,
representatives of the FMAA stated that significant releases from heating oil
tanks would be detected when they occur.

     .Government officials from Maine, Minnesota, Rhode Island, Wisconsin,
Barnstable County (MA), and Suffolk County (NY) reported that they do not
believe that degree-day monitoring by the oil distributors is an effective
leak detection monitoring practice (ICF 1988b).  Connecticut officials stated
that degree-day monitoring by distributors has not, to date, been useful for
identifying unknown releases; however, if a release is known to have occurred,
th^n such information can be helpful in identifying a potential source of the
release (ICF 1988b).  Similarly, New York officials could not identify a
single case (from either exempt tank systems or federally regulated USTs)  in
which inventory monitoring, by either the owner or a second party for either
type of these tank systems, was the initial source of a release report (NYSDEC
1987a and 1987b).  They did agree that inventory records can be useful in
identifying the source of a known release.  Even if degree-day monitoring is
an effective means of leak detection, not all heating oil tank systems would
be monitored by this system.  Not all distributors employ such a system, and,
for those that do, only those heating oil tank owners who commit to purchasing
heating oil under a "keep full" program from a single distributor would be
effectively monitored.

2.5  SUMMARY DESCRIPTION OF EXEMPT TANK SYSTEMS

     •    There are nearly twice as many exempt tank systems as regulated
          USTs.

     •    Exempt heating oil tank systems:

              comprise 87 percent of exempt heating oil and motor fuel tank
              systems;

              significantly outnumber regulated USTs (2.7 million versus 1.7
              million tank systems);
                                     2-19

-------
--  are comprised mostly (69 percent) of residential tank systems;
    and

--  are similar to regulated USTs in age and material of
    construction.

Exempt motor fuel tank systems:

--  comprise 13 percent of exempt heating oil and motor fuel tank
    systems;

--  are significantly outnumbered by regulated USTs (0.4 million
    versus 1.7 million tank systems); and

--  are similar in age and material of construction to regulated
    USTs.

Exempt tank systems usually use suction pumps while regulated USTs
most frequently use pressure pumps.

Exempt nonresidential heating oil tank systems are similar in
capacity to regulated USTs, but exempt residential and farm tank
systems tend to be smaller and have thinner walls.

Effective methods of leak detection and leak prevention are
practiced less often at exempt tank systems than at regulated USTs.
                           2-20

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                     3.  EXTENT OF PKT.BASKS FROM EXEMPT
                   HEATING OIL AND MOTOR FUEL TANK SYSTEMS
     Section 3 differs from Section 2 by looking closely at leaking exempt
heating oil and motor fuel tank systems rather than the total population of
exempt tank systems.  This section describes available information about the-
extent of releases from federally exempt heating oil and motor fuel tank
systems.  Unfortunately, detailed and documented information on this subject
is scarce; therefore, this section summarizes both documented and anecdotal
information on such releases.  This section also compares releases from exempt
tank systems with releases from regulated USTs and discusses the potential for
releases from exempt tank systems.

     Section 3.1 describes the sources of information concerning tank
releases.  Section 3.2 summarizes documented releases, including the number,
sources, and effects of reported releases.  Section 3.3 presents additional
information about releases collected from individual states, including a
summary of case histories for selected exempt tank system release incidents.
Section 3.4 compares releases from exempt tank system with releases from   .
regulated USTs.  Section 3.5 assesses the potential for releases from exempt
tank systems based upon information presented in Sections 2 and 3.

3.1  SOURCES OF INFORMATION

     The most comprehensive source of documented information on releases from
exempt heating oil and motor fuel tank systems is EPA's "State and Local
Release Incident Survey" (referred to a.j> the National Data Base in this
study).  This data base provides information on reported'releases from 1,978
exempt heating oil tank systems, 25 exempt motor fuel tank systems; and more
than 10,000 regulated USTs.  The National Data Base includes only those
releases that were reported to state and local government agencies from 1970
through the early part of 1985.  Because the data base was not compiled using
statistically valid sampling techniques, our ability to use the data to make
inferences on a national basis is limited.

     To supplement the National Data Base, additional information was obtained
through telephone inquiries to state and local government officials, an EPA-
sponsored workshop with five states and two counties, and visits to two other
states (New York and Maryland).  Although few states were able to assemble
comprehensive data, Maryland's Department of Environment provided an unusually
well-documented source of information on releases from exempt heating oil and
motor fuel tank systems.  This information is used to provide a comparison
with the National Data Base.

     Additional information obtained from New York State's Spill Response Data
Base and the interim findings of a tank corrosion study being conducted for
EPA by the Suffolk County Department of Health Services in New York (Pirn 1987
and 1988) is also used in the analysis to provide a comparison with the
National Data Base.  Additional information regarding these sources is
presented in Appendix B.
                                     3-1

-------
3.2  DOCUMENTED RELEASES

     This section summarizes documented information of releases from exempt
heating oil and motor fuel tank systems.  The discussion includes information
about the number and geographic location of reported releases,  characteristics
of the tank systems involved in releases, and the documented effects of
releases.  Additional information about releases from exempt tank systems is v
presented in section 3.3.
3.2.1
Number of Releases
     The National Data Base documents 2,003 releases from exempt tank systems
(Exhibit 3-1).-Reports of releases from regulated USTs are more common than
reports of releases from exempt tank systems.  The National Data Base includes
approximately five times as many reported releases from regulated USTs as from
exempt tank systems.  Interviews with a number of state officials and detailed
reviews of files in selected states suggest that the National Data Base
probably underestimates the number of releases from exempt tank systems (IGF
1987; IGF 1988b; ICF 1988c).  There may be more reported releases from .
regulated USTs because of the greater mobility and volatility of gasoline, the
product stored most frequently in regulated USTs, compared with that of
heating oils, the product stored most frequently in exempt tank systems.  In
addition, owners of regulated USTs may be more aware of possible leaks and
have systems with greater leak detection capability.

     The annual rate of reported releases from exempt tank systems increased
substantially from 1970 to 1984 (Exhibit 3-2) and .-ontinues to increase.  For
example, the National Data Base includes only 425  eports of releases from
exempt tank systems nationwide in 1984, compared with:

    •  237 reported releases in Maine during 1986;

    •  295 reported releases in Maryland over a 2-year period beginning late
       1985 (Exhibit 3-3)j1 and

    •  Approximately 1,500 reported releases of heating oil from exempt tank
       systems in New York over a 2-year period beginning late 1985 (Exhibit
       3-4).2

Thus, the number of reported releases in just these three states in 2 years
exceeds the number of incidents reported for the entire nation over the
previous 15 years.
     1 Maryland officials reported an additional 694 incidents of failures of
exempt tank systems, including tank testing failures; however, the extent that
stored product had been released in these incidents had not been determined.

     2 An unknown portion of these incidents, believed to be small, may
involve heating oil releases from USTs regulated under Subtitle I.
                                     3-2

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                                 Exhibit 3-1

       NUMBER OF REPORTED RELEASES FROM EXEMPT TANK SYSTEMS BY SECTOR
Product

Heating Oils:
Fuel Oil #1
Fuel Oil #2
Fuel Oil #4
Fuel Oils #5
and #6
Unspecified
Motor Fuels
TOTALS
(%)

Residential

5
222
10
5
155
21
418
(21)
Sector
Farm

0
6
0
0
5
4
15
ซD
ป.;
Total
Nonresidentiala

67
752
123
253
375
.. b
1,570
(79)
number

72
980
133
258
535
25
2,003
(100)
141

(4)
(49)
(7)
(13)
(27)
(1)
(100)
Source:  EPA State and Local Release Incident Survey.
     a  This category includes commercial, institutional,  government, and
manufacturing facilities.

     b  These USTs are not exempt from Subtitle I regulation.
                                     3-3

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                                 Exhibit 3-2
            Number of Reported Releases from Exempt Heating Oil
                        and Motor Fuel Tank Systems
Number
500

450

400

350

300

250
   Of
Reported 200
Incidents
        150

        100

         50

          0
                                    III
                       	1111111
                       1111111111
            1970 '71  '72  '73 '74  '75  '76 '77  '78  '79 ?80  '81  '82 '83  '84
                                   Year                      -,u
     Source: EPA State and Local Release Incident Survey.
                                 3-4

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                                     Exhibit 3-3


                          REPORTS OF RELEASES FROM EXEMPT
                 HEATING OIL AND MOTOR FUEL TANK SYSTEMS IN MARYLAND

                                    (1985 TO 1987)

                            (Number  of  reported  incidents)
Product
Heating Oils:
Fuel Oil #1
Fuel Oil #2
Fuel Oil #4
Fuel Oils #5
Sector
Residential Farm Nonresidentiala
6 -- 8
34 -- 159
5 .
2 -- 19

Unknown
Sector Total
2 16
16 209
5
-- 21
         and #6
   Unspecified
11
 27
            39
Motor Fuels:

   Gasoline
TOTALS
54
218
21
295
Source: ICF 1988c.
     a This category includes commercial, institutional, government, and manufacturing
facilities.

     k These USTs are not exempt from Subtitle I regulation.
                                         3-5

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                                     Exhibit 3-4


        REPORTS OF RELEASES FROM EXEMPT HEATING OIL TANK SYSTEMS IN NEW YORK

                                    (1985 TO 1987)

                           (Number  of reported incidents)
Product
Heating Oils:
Fuel Oil #2
Fuel Oil #4
Fuel Oil #6
TOTALS
Sector Estimated Total
Residential Nonresidential Under grounda

66 1192 1258
1 135 136
0 110 110
67 1437 ; 1504
5 '-
Source: IGF 1987.
     a  New York State Department of Environmental Conservation (NYSDEC)  records
reported releases of petroleum products from aboveground and underground tanks in the
same data base without distinguishing the tank type for each incident.   These
estimates represent judgments of NYSDEC officials regarding the total number of
reported incidents that were from exempt tank systems.
                                         3-6

-------
    The increase in the number of reported releases is probably attributable
to a combination of factors:  (1) the recent increase in the awareness by tank
owners and operators that their tanks may leak and possibly threaten public
health and safety; (2) the development of new environmental protection
programs and the increase in staffing of existing programs at the state.and
local level during the 1970s and 1980s (in fact, few programs kept track of
such problems before 1970); and (3) the large number of underground heating
oil tank systems installed during the 1950s and 1960s that have now reached „
the age at which tank failures are more likely to occur.

    Releases reported in the National Data Base come from the following tank
system sectors:

    •     About 79 percent from underground nonresidential tank systems (even
          though this sector comprises only 26 percent of the exempt tank
          system population);

    •     About 20 percent from underground residential tank systems (with
          single-family residences accounting for 83 percent of these
          releases);

    •     About 1 percent from underground residential and farm motor fuel
          tank systems (with single-family residences accounting for 80.
          percent of these releases);

    •     Less than 1 percent from underground farm heating oil tank systems.

    There were only 11 releases from farm heating,oil tank systems reported in
the National Data Base (Exhibit 3-1), and Maryland officials did not report
any releases from farm heating oil tank systems (IGF 1988c).  However,-.
reported releases from farm residences may not have been easily distinguished
from residential releases in the available data.

    Some reasons for the disproportionate number of reported releases from
exempt nonresidential tank systems are:  (1) the larger quantities typically
released from nonresidential systems, making detection of releases easier; (2)
the more extensive state and local regulations for these tank systems than for
federally exempt residential or farm tank systems; and (3) the greater
familiarity of nonresidential owners and operators with leak detection
practices and release reporting requirements.

3.2.2  Geographic Location of Reported Releases

    Based on the National Data Base, 71 percent of reported releases of
heating oil from exempt tank systems have occurred in the Northeast (Exhibit
3-5).  This concentration of reported releases from exempt heating oil tank
systems is consistent with their geographic distribution (Exhibit 2-2).
                                     3-7

-------
                                    Exhibit 3-5
The Frequency off Reported Releases from Exempt Heating Oil Tank Systems
                            by Geographic Region
                                                         71%
    Source: EPA State and Local Release Incident Survey (based on 1,905 incidents nationwide, 1970-1985).
    1 Totals for the West include Alaska and Hawaii.
                                    3-8

-------
3.2.3  Age of T^alc-tTig Exeupt Tank Systems

     The mean age of exempt tank systems with releases reported in the
National Data Base varied little among the sectors:  20.0 years for
residential tank systems, 20.2 years for nonresidential tank systems, and 15.5
for farm tank systems.   Maryland data are consistent with these reported ages
(IGF 1988c).  More than 80 percent of the reported incidents in Maryland were
from tank systems at least 16 years old.

3.2.4  Quantity of Product Released

     For those incidents in the National Data Base with the quantity of
release reported, most exempt heating oil tank systems incidents in both the
residential and nonresidential sectors had releases of less than 500 gallons
(Exhibit 3-6).  In both sectors, releases were reported to be less than 100
gallons in about 40 percent of the incidents.  Residential tank system
releases were generally smaller than releases from nonresidential tank
systems.

     The accuracy of many of the documented estimates of the quantity released
is generally unknown.  New York State Department of Environmental Conservation
representatives expressed a concern that the estimates of quantity released in
New York were generally too low.  New York State law requires the reporting of
releases, but state officials felt there is a tendency for tank owners to
minimize their description of the severity of a release during the initial
reporfJ.ng of a release (NYSDEC 1987b).  Although the amount of product
reported to be released is generally small, the amount of product actually
released may be very large in some instances (see Section 3.3.2).

3.2.5  Products Released

     More than two-thirds of the releases from exempt tank systems reported in
the National Data Base for which the product is identified involve fuel oil
No. 2.  The proportion of the releases from residential facilities involving
fuel oil No. 2 (92 percent) was higher than that at nonresidential facilities
(63 percent).  Fuel oil No. 2 was the product released in almost all single-
family residential incidents, whereas multiple-family units more commonly
reported releases of the heavier grade fuel oils.  Fuel oil No. 2 was the only
heating oil cited in releases from the farm sector where the product is
specified.  In contrast, nearly all releases of residual heating oils (fuel
oil Nos. 4, 5, and 6) were from nonresidential tank systems.

     Very little information is available concerning releases of motor fuels
from exempt tank systems.  The National Data Base contains only 25 reported
incidents in 15 years.  Of these 25 motor fuel releases, 20 originated from
exempt tank systems serving single-family residences, 1 from a multiple-family
building, and 4 from farms.  Maryland reports 13 additional cases (less than 2
percent of the total) of release or tank test failure by exempt motor fuel
tank systems over a 2-year period.  These incidents also originated primarily
from residential facilities.
                                     3-9

-------
                                        Exhibit 3-6

       Quantity of Product Released from Exempt Heating Oil Tank Systems
 Percent  40
   of
Reported 30
incidents
                    Residential Sector

                    Nonresiderrtial Sector
                   
-------
     All but one of the motor fuel releases documented in the National Data
Base involved gasoline (the remaining release involved diesel fuel).
According to state and local government officials, the low frequency of
releases reported from exempt motor fuel tank systems may result from owners
and operators not inspecting their tank systems for releases.  In addition,
exempt motor fuel tank systems are commonly found in rural areas where the
effects of a leaking tank system may not be noticed as quickly as releases in
urban areas.                   •                                             *

3.2.6  Location within Tank Systeos Where Releases Occur

     Releases of heating oil from exempt tank systems originated at the tank
itself in more than 50 percent of the incidents reported in the National Data
Base (Exhibit 3-7).  In nearly 30 percent of the incident reports, the fill
pipe is indicated as the source of the release, suggesting an overfill.  Other
piping is cited as the source of the release in about 20 percent of the cases.
Maryland data revealed that the fill pipe and the tank were the most common
sources of releases, although fittings, supply lines, vent lines, and return
lines were also commonly cited (IGF 1988c).

     The 25 release incidents from exempt motor fuel tank systems reported in
the National Data Base included a total of 66 sources of release, an average
of more than two sources within each tank system.  That is, multiple source
releases were identified when the release incident was investigated.   Tanks
are the most commonly listed source of release for exempt motor fuel tank
systems, foil  red by fill pipes and other parts of the piping.

     Multiple s urces of releases were also reported for heating oil tank
systems.  Reports of multiple sources of releases at exempt tank systems may
indicate that these tank systems are not being closely monitored and that tank
system failures are not being detected early.

3.2.7  Environmental Damages and Corrective Actions Taken

    The National Data Base yields very little information about specific
environmental and health effects associated with releases from exempt tank
systems.  The lack of data, however, should not be interpreted as though the
effects of these releases are minimal.  Environmental effects may not
necessarily be observed when release incident reports are completed,  and
effects may occur at points some distance from the original source of the
release.  Thus, any interpretation of the available data on environmental
damages and health impacts must recognize the absence of systematic reporting
and monitoring of the environmental and health effects of reported releases.

Heating Oil Tank Systens

    Almost all of the 1*978 cases of heating oil releases from exempt tank
systems recorded in the National Data Base indicate at least some degree of
soil contamination (Exhibit 3-8).  Most of the incidents also report
contamination of ground water or surface water.  Nine of the incidents include
releases to private or municipal wells, and six incidents indicate impacts to
human health.
                                     3-11

-------
                                       Exhibit: 3-7
LOCATION WITHIN EXEMPT HEATING OIL TANK SYSTEMS WHERE RELEASES OCCUR
(Percent of product releases for incidents that specified the location)
V
Location
Tank
Fill Pipe
Piping
Other
TOTALS
Number of
Responses
:
No. 1'
66
13
16
5
100

63 .

No. 2
50
28
21
1
100

835
Fuel Oil
No. 4 No. 5 or 6 Unspecified
33 35 - 63
40 46 19
24 17 17
32 1
100 100 100

120 220 " 431
Overall
Frequency
( Weigh ted Avg.i
51
28
20
1
100

1,669
Source:  EPA State and Local Release Incident Survey (based on 1,669 responses3).
     a  A response' refers to an individual citation regarding the location of a release.
More than one location is commonly indicated for any given release incident.
                                         3-12

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   Environmental Damages Reported from Exempt Tank System Releases
          1200
          1000
           800

Number
   of      eoo
Reported
Incidents
           400
           200
                           Releases to:
                           •i Soil
                              Ground Water
                              Surface Water
                  Motor
                  Fuels
No. 1
No.2     No.4    NOS.5&6  Unspecified
                                     FidlOils

    Source: EPA State and Local Release Incident Survey.
                                       3-13

-------
    In Maryland, all of the 295 known release incidents indicate at least some
degree of soil contamination.  In addition, there are 26 cases of ground-
water contamination, and three cases of surface-water contamination (IGF
1988c).  These reports, however, probably understate the true extent of the
problem, because most of these incidents were taken from summaries of initial
release reports made before the extent of damage had been fully investigated.
                                                                            <
    A general pattern can be seen in the relative probabilities that various
environmental media will be affected by releases of heating oil from exempt
tank systems.  Regardless of whether all cases are aggregated or if they are
examined by sector, soil contamination is most commonly cited, followed by
contamination of ground water, surface water, and wells, in that order.

    A broad range of corrective actions taken in response to releases from
exempt tank systems is documented in the National Data Base.  The most
commonly cited corrective action is removal or replacement of the tank or
piping, followed by the use of barrier techniques, and various unspecified
methods of product recovery.  Soil excavation and use of absorbent materials
were commonly reported.  Although soil excavation and barrier techniques
appear to be more common with the residual fuel oils (Nos. 4, 5, & 6) compared
with the middle distillates (fuel oil Nos. 1 & 2), the differences are not
great (Exhibit 3-9).   In general, however, advanced methods, such as steam
stripping and chemical techniques, are reported infrequently.

Motor Fuel Tank Systens

    All 25 of the releases from exempt mctor ฃ el tank systems recorded in the
National Data Base indicated both soil and ground-water contamination.
Twenty-three releases also reported contamination of surface water.  Maryland
reported 13 failures of exempt motor fuel tank systems in a 2-year period;
five were known to have released stored product to the soil and one resulted
in the contamination of ground water.

3.3 ADDITIONAL INFORMATION ON RELEASES

    Much useful information on releases from exempt tank systems can be
obtained from individuals who have experience with releases from exempt tank
systems, but may lack quantitative data, or who have data on the condition of
tank systems as they are removed from the ground rather than data on releases.
Such informational sources can provide anecdotal or qualitative data that
helps document the extent of releases from exempt tank systems.  This
information includes illustrative cases of releases, as well as both
quantitative data and opinions of experts on the extent of releases, their
causes, and the need to regulate exempt tank systems.  Section 3.3.1
summarizes the interim findings of a study on tank corrosion.  Section 3.3.2
presents the findings, comments, and recommendations from meetings with
selected government officials.  Section 3.3.3 qualitatively summarizes a few
case histories of releases from exempt tank systems.
                                     3-14

-------
                                             5%
          Frequency of Use of Selected Corrective Action Techniques
                      (Percent of Corrective Actions Reported)
Percent
  Use
                                                    Releases of:
                                                    •I Fuel Oil Nos. 1 & 2

                                                        Fuel Oil Nos. 4.5, & 6
                 Removal or
                 Replacement
               of Tank or Piping
  barrier
Techniques
Absorbent
 Materials
   Soil
E cavatlon
    Source: EPA State and Local Release Incident Survey (based on 440 responses for Fuel Oil Nos. 1 & 2
    and 143 responses for Fuel Oil Nos. 4, 5, & 6).
                                         3-15

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3.3.1  Interim Results from a Tank Corrosion Study in Suffolk County, New York

    A study of tank corrosion, being conducted for EPA by the Suffolk County
Department of Health Services in New York, has revealed some new information
about underground petroleum tanks that have been removed from service and
taken out of the ground.  Interim results of the study (through February 1988)
are available for 317 tanks removed from the ground over the previous one year
period.  According to the most recent interim report (Pirn 1988),  89 of the 317
tanks examined qualified as exempt tanks.  Of the 89 exempt tanks, 31 (35
percent) had perforations and several tanks had multiple holes (e.g., one tank
had 31 holes, another had 29 holes, and a third had 16 holes).

    Although the sizes of the 31 exempt tanks with holes ranged from 275
gallons to 5,000 gallons, 26 tanks had a capacity of 1,000 gallons or more.
All of the tanks with holes contained fuel oil No. 2, except for one 5,000-
gallon tank that contained fuel oil No. 4.  The ages of the exempt tanks with
holes ranged from 6 to 55 years, although more than half (16 tanks) were
either 26 or 27 years old.  Twenty-three of the 31 tanks (74 percent) failed
from exterior corrosion, four from interior and exterior corrosion, and two
suffered weld failures.  None failed from interior corrosion alone.  Seven of
the tanks with holes had been in direct contact with ground water.

    The information from this continuing study is useful because, although no
information on releases is provided, it reveals that exempt tanks seem to
behave in a manner that is very •similar to regulated steel tanks.  For
example, the percentage of exemy': f-taiks with holes was essentially the same as
the percentage of all tanks with holes (35 versus 34 percent, respectively;
Pirn 1987 and 1988).                                                     ^

3.3.2  Information from State TJST Program Officials

     EPA's meeting with state and local officials on December 2,  1987,
provided additional information from selected state and county officials who
have had experience with exempt tank systems.  Exhibit 3-10 summarizes the
information gathered at this meeting (IGF 1988b).  Representatives from each
state described several cases of release incidents involving exempt tank
systems.  The consensus of the representatives of the five state and two
county programs was that:

     •   Exempt tank systems corrode and leak at approximately the same rate
         as regulated USTs;

     •   Releases from exempt tank systems contaminate ground water, surface
         water, and, in some cases, private and public wells;

     •   Contamination of ground water and wells is more common in areas with
         hydrogeological conditions that allow for rapid movement of product
         and is of greater concern in areas that rely heavily on ground water
         for drinking water;
                                     3-16

-------
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     •   Releases of fuel oil No. 2 account for the majority of incidents
         resulting in ground-water contamination;

     •   More exempt tank system release incidents are reported from the
         nonresidential sector than the residential sector;

     •   Farm tank systems are a concern, although there is little data
         available to document the problem; and             •                ••

     •   There is a definite need for some regulation of exempt tank systems.

     Similar inquiries were made of officials from Maryland and New York
during visits to collect data from UST programs that regulate federally exempt
tank systems.  Documentation of releases reported from Maryland is presented
in Section 3.2.  Based on estimates provided by New York State Department of
Environmental Conservation (NYSDEC) officials, there were more than 1,500
reported release incidents involving underground heating oil tank systems in
New York over a 2-year period (Exhibit 3-4).  NYSDEC believes that more than
90 percent of the releases from exempt tank systems were from industrial
facilities.  Private dwellings account for about 5 percent of the total,
virtually all involving fuel oil No. 2 (IGF 1987).

     Officials from both Maryland and New York also indicated a need for
exempt tank systems to be regulated.  Some of these tanks are already being
regulated in various states throughout the country (see discussion of current
state regulations in section 5).  Maryland officials find that requiring tank
testing has identified many leaking exempt tank systems that would previously
have gone unnoticed, and that almost one-fifth of the tank test failures
revealed leakage rates greater than one gallon of product, per hour (10 times
the specified standard in the Subtitle I regulations).

3.3.3  Sumaries of Selected Release Incidents

     Most of the findings presented thus far regarding the extent of releases
from exempt tank systems have been limited to information that is easily
quantified.  Exhibit 3-11 presents five brief case histories of exempt heating
oil incidents.  This exhibit is not intended to be a comprehensive or even
representative list of documented release incidents for which descriptions are
available; instead, Exhibit 3-11 represents incidents with either significant
environmental effects or releases of large quantities of product over a long
period of time.

     Even though most releases are less than 500 gallons, conclusions that may
be drawn from these case histories of release incidents are:

     •    Releases from exempt tank systems may continue for long periods of
          time without detection, during which time the amount of product
          released may become large; and

     •    Persistence of the released product in the environment can lead to
          protracted and expensive remedial action efforts.
                                     3-18

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                         Exhibit  3-11

      SUMMARY OF SELECTED RELEASES FROM EXEMPT TANK SYSTEMS
    Maryland.   Department of Environment officials report that
cleanup and containment action has continued for one exempt tank
system release case for 14 years.   The release was first detected
when a nursing home switched from fuel oil No. 6 to fuel oil No. 2
and found that consumption greatly increased.  The consumption
increase was actually due to leakage; an estimated total of
300,000 gallons of product has been released into the soil from
the tank system, 280,000 gallons of which has been recovered.

    Massachusetts.  The Barnstable County Health and Environmental
Department (RED) has documented a large release of fuel oil No. 2
from a 275-gallon exempt heating oil tank system serving a private
residence.  The leak contaminated 15 cubic yards of soil, an on-
site well, and a nearby pond.  The extent of damage led HED
officials to believe product was released over an extended period,
possibly as long as 10 years.  Corrective action is expected to
cost $80,000 and will include removing the underground tank and
contaminated soil and installing monitoring wells and a product
recovery system.

    Minnesota.  In 1975 the Pollution Control Agency received an
initial complaint of oil seepage into a basement, but the source
of the release could not be determined at that time.  Later, when
the source (a creamery) was found, product recovery wells
recovered 4,000 gallons of fuel oil No. 5, and the source -- a ;
leaking 14,000-gallon tank (which had a hole) --was removed." - " .
Twelve years later, oil seeping into nearby basements is still
being reported, and the state has determined that the recovery
efforts need to continue.

    A second case, also requiring ongoing remedial action,
involved a commercial tank system which released fuel oils No. 2
and No. 5 and caused extensive contamination of soil and ground
water.  Fuel oil No. 5 had not been used for several years before
the leak was detected, indicating the release and ground-water
contamination persisted over a long period of time.  The state has
conducted site remediation, but does not believe the problem has
been fully resolved, even 10 years after the initial report of the
spill.

    Rhode Island.  The Department of Environmental Management
reports that a leak of fuel oil No. 2 from a tank serving a
private residence has contaminated five private wells, requiring
extension of the public water supply system.  Total costs of
remedial action for this case are estimated to be $200,000.
                               3-19

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3.4  COMPARISON OF EXEMPT TANK SYSTEMS AND REGULATED USTs INVOLVED IN REPORTED
     RELEASES

     To provide a context for evaluating the magnitude of the threat of
releases from exempt tank systems, the following section compares data from
the National Data Base for regulated tFSTs and exempt tank systems.
                                    *                                        ^
3.4.1  Differences

     The National Data Base reveals several differences among releases
reported from exempt tank systems and regulated USTs.  Key differences
identified include geographical distribution of release incidents, type of
facility where the release occurred, and tank capacity.

Geographical Distribution of Release Incidents

     Releases from exempt tank systems reported in the National Data Base
occur primarily in the Northeast, an area characterized by high heating oil
consumption.  In contrast, regulated UST releases are more evenly distributed
across the country.

Facility Type                                   •

     Tank systems serving nonresidential facilities were involved in 78
percent of the reported releases from exempt tsrtik systems.  Releases from
exempt nonresidential tank systems originate fvom a broad range of facilities,
including commercial, manufacturing, residential, military, government, farm,
and institutional facilities.  In"contrast, the National Data Base reveals
that 63 percent of the reported releases from regulated USTs take place at
retail gas stations (IGF 1988a).   Thus, exempt tank systems involved in
releases are more widely distributed among different sectors and operators
than are regulated USTs.                                                   ',

Tank Capacity

     The average capacity of exempt tank systems reported to be leaking is
smaller than the average capacity of regulated USTs reported to be leaking,
but large tanks were more frequently a problem for exempt tank systems than
regulated USTs.  Exempt tank systems involved in releases may also be
characterized by a wider range, of tank capacities than regulated USTs
reporting releases (Exhibit 3-12).  There are significantly more exempt tank
systems than regulated USTs with capacities less than 1,000 gallons.

3.4.2  Similarities

     Similarities between releases reported from regulated USTs and exempt
tank systems include the quantity of product released, age of tank system at
release, material of construction, and cause of release.
                                     3-20

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                                       Exhibit 3-12

           Capacity of Exempt and Regulated USTs Reporting Releases
 Percent
   of
Reported
Incidents
                      Exempt Tank Systems

                      Regulated USTs
                     1,000
1,001 - 3,999    4,000 - 11,9C,-
 Tank Capacity (Gallons) g *
,000
      Source: EPA State and Local Release Incident Survey (based on 805 exempt and 3,532 regulated UST
      releases).
                                         3-21

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Quantity of Product: Released

      Based on incidents contained in the National Data Base, the exempt and
regulated populations exhibit similar characteristics with respect to the
quantity released.  This  is  particularly true when the comparison is between
nonresidential exempt tank systems and regulated USTs, because these two tank
populations tend to have  larger  capacities and fuel releases than exempt
residential and farm tank systems.   Although the average capacity of exempt .
tank systems involved in  releases is smaller than the average capacity of
regulated USTs involved in releases,  the average reported quantity released
for each population is nearly the same (see Exhibit 3-13).  For both
populations, the most commonly reported quantity released is 100 gallons or '
less, with about a  third  of  each population reporting release quantities in
this range (these quantities include spills and overfills).  For both exempt
tank systems and regulated USTs,  the number of releases decreases as the
release  quantity increases.

Age of Tank System  at Release

      The tank age data for reported releases from both regulated and exempt
populations show similar  trends  (Exhibit 3-14).  The mean age at the time of
the reported release was  20  years for exempt tank systems and 18 years for
regulated USTs.

Material of Construction                                               ;

      More t-Jhau 80 percent of the tank systems reporte  to be leaking in both
Xhe exempt and regulated  populations were constructed of steel, although the
proportion of steel tanks was slightly higher for the exempt population.

Cause of Release

      It  is not possible to analyze quantitatively information regarding the
cause of release in the National Data Base because of the ambiguous responses
recorded in the survey.   Survey  respondents were allowed to select up to four
causes for release  on the survey form.  Although the options listed were not
mutually exclusive, structural failure, corrosion, spills, and overfills were
the most commonly cited causes of releases for both regulated USTs and exempt
tank systems.  In a study examining underground tanks as they are removed from
the ground, external corrosion,  rather than internal corrosion, was the
predominant cause of holes in steel tanks (Pirn 1987 and 1988).

3.5  POTENTIAL FOR  RELEASES                                               •

      Limited documented information is available about releases from exempt
tank systems.  The  National  Data Base contains only information that has been
reported to states  and local agencies and may represent only a small fraction
of actual releases  from exempt tank systems.  These types of tank systems
usually  are not equipped  with release detection devices, receive little
management attention, and generally do hot have spill and overfill protection
devices.  Evaluating the  potential for releases must, therefore, take into
account  the factors that  affect  the likelihood for failures to occur.  This
                                     3-22

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                                    ^Exhibit 3*13

         Quantity of Product Released from Exempt and Regulated USTs
           30
 Percent
   of
Reported   20
Incidents
                                                   Exempt Tank Systems

                                                   Regulated USTs
                   <100
  101 - 500      501 - 2,500
Quantity Released (Gallons)
> 2,500
      Source: EPA State and Local Release Incident Survey (based on 1,189 exempt and 4,765 regulated UST
      releases).
                                            3-23

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                                        Exhibit 3-14

              Age of Exempt and Regulated USTs Reporting Releases
 Percent
   of
Reported
Incidents
                                                       Exempt Tank Systems

                                                       Regulated USTs
                 1-5   6-10  11-15  16-20  21-25  26 - 30  31 - 35   >36
                                        Age (years)  -   ;


      Source: EPA State and Local Release Incident Survey (based on 134 exempt and 1,356 regulated UST
      releases.  Incidents reporting an age of less than one year are omitted).
                                          3-24

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section summarizes the potential for releases from exempt tank systems using a
comparison with regulated USTs as a basis for the discussion.

3.5.1  Cause of Release

     There appears to be no significant difference in the potential for
releases from exempt tank systems versus regulated USTs based on material of
construction.  Both populations are constructed most often out of bare steel*
•and are of similar ages.  There also appears to be no major difference in the
causes of releases reported from exempt t^rik systems and regulated USTs.   In
both cases, structural failure, corrosion, spills, and overfills are the  most
frequently cited causes of release.  In addition, there is no evidence to
suggest that the characteristics of heating oils or motor fuels significantly
affect their potential for corrosion of the tank system, especially since
external rather than internal corrosion appears to cause tank corrosion more
frequently (Pirn 1987 and 1988). .

     PMAA (1987) suggested that stray electrical currents increase the rate of
external corrosion of a tank and that these forces are more prevalent at
regulated UST facilities.  Assuming this is true and ignoring the importance
of site-specific conditions, factors such as these might decrease the rate of
corrosion, but not the ultimate result (bare steel tanks would still corrode).
Comparison of the age of exempt tank systems with that of regulated USTs  that
have released product fails to support the claim that exempt residential  tank
systems are significantly older when they corrode than are regulated USTs,.

3.5.2  Quantity of Releases                       '

     Although the potential to release stored substances is believed to be
similar between exempt tank systems and regulated USTs, it is difficult to
ascertain whether the potential total amount released is greater.fp.r.regulated
USTs than for exempt tanks.  The total amount of product released is a
function of total amount stored, the rate of release, and the duration of the
release.  Determining the cumulative effects of these different.factors is
difficult.

     The storage capacity of nonresidential exempt heating oil tank systems is
similar to the storage capacity of regulated USTs; however, exempt residential
and farm tank systems tend to be smaller. . Thus, the maximum potential
quantity released from a sudden catastrophic release is similar between exempt
nonresidential heating oil tank systems and regulated USTs, but is less for
exempt residential and farm tank systems than for regulated USTs.

     The rate of release of sto. ed product is expected to be slower from
exempt heating oil tank systems than regulated USTs for two reasons.  First,
exempt tank systems typically store heating oils while regulated USTs more
frequently store gasoline.  Because of the higher viscosity of fuel oils  than
motor fuels (see Section 4), heating oils would typically drain more slowly
from a tank system assuming other variables are the same.  This is
particularly true of some of the residual fuels (such as fuel oil Nos. 5  and
6), which may have to be heated in the tank in order to flow.  Second, exempt
tank systems typically use suction pumps to deliver the stored substance from
                                     3-25

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the tank to the delivery point, but regulated USTs more frequently use
pressure pumps.  When a. leak occurs in the piping, the most frequent location
of reported releases in regulated USTs, the products sto'red in exempt tank
systems are typically under negative pressure in the supply line and low
positive pressure in the return line (which carries unused fuel from the
burner back to the tank).  In contrast, the products stored in regulated USTs
are typically under much higher positive pressure.  The viscosity and pressure
differences significantly increase the rate of released product from the UST> •
system for regulated USTs, compared with exempt tank systems.

     Although differences in viscosity among stored products may affect the
rate of release, the effect of viscosity on the quantity released is unknown.
In one potential scenario, a slower release rate may mean less free product is
released to the environment, because the problem is corrected before much
stored product has been released.  In contrast, it is conceivable that a
slower release rate of a more viscous product could go undetected and
consequently, a higher total volume could be released over a longer period of
time.  Documented data reveal that exempt tank systems are as capable as
regulated USTs of generating large releases over protracted periods of time
(see Exhibit 3-11).

     The reported quantity of releases from both exempt tank systems and
regulated USTs tends to be small -- more than two-thirds of reported releases
are less than 500 gallons.  Although releases from exempt residential tank
systems tend to be smaller in quantity than releases from regulated USTs,
these differences, in general, are not appreciable.

3.5.3  Number of Potential Releases             '•'"

     The number of potential releases is much higher for exempt tank systems
than for regulated USTs because exempt tank systems are nearly twice as
abundant as regulated USTs.  (This discounts differences between these two
groups regarding the likelihood of repeated releases from the same tank   '
systems.)  The residential sites represent nearly 60 percent of the potential
sites for releases from exempt tank systems, exceeding the number of potential
sites for releases from regulated USTs.

     Although there are more potential sites for releases from exempt tank
systems than regulated USTs, there are fewer reported releases from exempt
tank systems.  This discrepancy could be due to differences in the occurrence,
potential, detection, and reporting of releases.  Analyses of the likely
factors affecting the initiation of a release suggest that even if the true
occurrence of releases (and not just reported releases) has been less to date
for exempt tank systems than for regulated USTs, the potential for release may
be similar.  Exempt tank systems may corrode more slowly than regulated USTs,
but they still corrode and will eventually leak.  Information regarding the
fate and transport of released product, which affects the- likelihood of
detection, is presented in Section 4.
                                     Z-26

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4.   POTENTIAL IMPACTS ON HUMAN HEALTH AND THE ENVIRONMENT FROM PRODUCTS
     PRT.KASiiT> FROM EXEMPT HEATING OIL AND MOTOR FUEL TANK -SYSTEMS
     All of the products stored in exempt heating oil and motor fuel tank
systems contain noncarcinogenic substances that can cause adverse health
effects.  In addition, some of the products contain known or probable
carcinogens.  Releases of heating oil and motor fuels from exempt tank systems
can adversely impact human health through contamination of air, soil, surface
water, and, most significantly, ground water.

     Most releases from exempt tank systems travel similar routes as releases
from regulated USTs.  Products from releases can saturate soils and dissolve
in ground water.  Volatile components of stored products can also vaporize and
contaminate the air.  The most likely route to human exposure of the water-
soluble components of petroleum products in exempt tank systems is through
drinking, bathing, and other direct contacts with contaminated water, or by
breathing vaporized components while showering.  Releases can also seep into
basements, exposing humans directly to pools of released products, as well as
to additional hazards of fire and explosion.  Humans can also be exposed
through contact with contaminated soil.  This exposure can occur when
fluctuations in the water table cause released petroleum products to rise to
the surface and during construction operations and cleanup of a release.

     Potential impacts to human health from releases of products stored in
exempt tank systems were evaluated by:
                                                .,.;/"'
     •    Identifying the physical properties and chemical constituei is;

     •    Investigating the mechanisms by which the released products migrate
          after they are released; and

     •    Analyzing the hazard to human health and the environment posed by.
          released products.


4.1  TOXICITIES OF PRODUCTS STORED IN EXEMPT TANK. SYSTEMS

     Exempt tank systems are used to store a variety of petroleum products',
including gasoline and diesel fuel (motor fuels), and fuel oils Nos. 1, 2, 4,
5, and 6 (heating oils).  With the exception of gasoline, stored "in less than
13 percent of exempt tank systems, the toxicities of these fuels have not been
well studied, and only limited information is available regarding the fuels as
mixtures.   Gasoline, which has been the subject of extensive study under
EPA's RCRA Subtitle I regulatory program, is already classified as a probable
human carcinogen (API 1983, USEPA 1985a, IGF 1988a).  As a result, this
discussion of the toxicities of products stored in exempt tank systems focuses
primarily on heating oils, which account for most of petroleum products stored
in exempt tank systems.
                                     4-1

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     The exact compositions of heating oils vary widely depending on the
source of the crude oil and the refining process used; standards for petroleum
products are based on physical properties and not constituents.  It is
possible, however, to describe the health effects of some of the likely
constituents of the fuels.  Because concentrations fluctuate dramatically and
many of the constituents of the fuels are unknown, the toxicity suggested by
the components may not be the actual toxicity of the product.

     Exhibit 4-1 summarizes the health effects of some of the constituents of
gasoline and heating oils.  Additional toxicity information and concentration
data for the constituents can be found in Appendix C.

4.1.1     Middle Distillate Fuels: Diesel Fuel, Kerosene, and Fuel Oil Nos, 1
          and 2   '  '                                                   ""'.'?'/ '

     Some members of the middle distillate family (fuel oil No. 2 and diesel
fuel) have been shown to be weak to moderate carcinogens when painted on the
skin of laboratory animals (USEPA 1985c).  In addition, these fuels contain
other substances that may cause kidney, liver, and eye damage in humans.  In
humans, toxic kidney effects were reported in one adult who used diesel fuel
to clean his hands and arms for several weeks, and in another who used diesel
fuel as a shampoo (Crisp et al. 1979; Barrientos et al. 1977).

     The middle distillate fuels contain compounds known as polynuclear /-,
aromatic hydrocarbons (FAHs), which may be a. significant health concern/  One
of the PAHs found in J*he middle distillates, naphthalene, causes tremors.,
vomiting, and eye daajage (IARC 1983;  1984; USEPA 1982).  Two others
(benzo(a)anthracene and benzo(a)pyrene) have been* detected at very low levels
in several samples of fuel oil No. 2 and are probable human carcinogens.
(Tomkins and Griest 1987; Pancirov and Brown 1975; USEPA 1986b).  ,   ? ,,

     In addition to PAHs, the middle distillates contain cresols and phenols.
These compounds are toxic to the liver and kidneys (USEPA 1985d).  Three of
the toxic constituents of gasoline, namely toluene, xyienes, 'and ethylbenzene,
are also found in the middle distillates; however, they are present in these
fuels in much lower concentrations.  Other constituents found in the middle
distillates are also known to cause adverse effects on human health (Appendix
C).

4.1.2     Residual Fuels: Fuel Oil Nos. 4, 5, and 6

     The carcinogenicity of the residual fuels has not been well studied.
There are, however, several reports indicating that at least two of the   :
blending stocks used in their production are carcinogenic in mice (USEPA
1985b; API 1985).  In fact, one of them (catalytically cracked clarified oil)
is recognized as one of the most carcinogenic materials in the petroleum
refinery (USEPA 1985b; API 1985).

     The known constituents of most concern in the residual fuels are the
PAHs.  These compounds are present in higher concentrations in the residual
fuels than in gasoline or the middle distillates.  The two PAHs that are
probable human carcinogens and have been found in the middle distillates in
                                     4-2

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                                 Exhibit 4-1

              ADVERSE HEALTH EFFECTS ASSOCIATED WITH EXPOSURES
            TO  SOME CONSTITUENTS OF MOTOR FUELS AND HEATING OILS
FUEL TYPE
CONSTITUENT
POTENTIAL HEALTH EFFECTS
Gasoline
Benzene
Human carcinogen
Middle
Distillates

(Kerosene, diesel
fuel, fuel oil
Nos. 1 and 2, and
some blends of
No. 4)
Polynuclear aromatic
hydrocarbons (PAHs):

  naphthalene

  benzo(a)anthracene

  benzo(a)pyrene

Cresols and phenols
Causes malaise, tremors, vomiting,
  and eye damage
Probable human carcinogen

Probable human carcinogen

Irritates skin, mucous membranes,
and^eyes
May be canes? promoters
Residual
Fuels

(Fuel oil Nos.
5 and 6, and
most blends of
No. 4)
PAHs:

  benzo(a)anthracene

  benzo(a)pyrene

  chrysene

Catalytically cracked
clarified oil
Probable human carcinogen

Probable human carcinogen

May be a .carcinogen


Potent carcinogen in animals
Source:  Based on literature review performed by IGF Incorporated.
                                     4-3

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small amounts have been, found in higher concentrations in fuel oil No. 6 and
are probably present in the other residual fuels.  In addition, a third PAH,
chrysene, may be carcinogenic in animals  (IARC 1983).  Because the residual
fuels tend to have relatively high concentrations of these compounds, PAHs
other than the ones mentioned here may also be present but have not been
reported.  Arsenic, a human carcinogen, has been detected at low
concentrations in samples of fuel oil Nos. 4 and 6 (GCA 1983; USEPA 1986b).
As with gasoline and the middle distillates, the constituents discussed above
•are probably not the only toxic constituents present in the residual fuels.

4.2  FATE ADD TRANSPORT OF PgTJgASKn PRODUCTS

    The physical properties of motor fuels and heating oils affect how these
products move in the ground after being released from an underground storage
tank system.  The specific properties and transport mechanisms are described
below for a typical release as it migrates downward from the tank, through the
unsaturated zone, until it reaches the water table and migrates in the general
direction of ground-water flow (Exhibit 4-2).

4.2.1    Transport Through the Unsaturated Zone

    Transport of product in the unsaturated zone is characterized by a
gravity-driven downward flow, with some lateral spreading of the plume
depending on differences in soil permeability (i.e., number and size of
pores).  A primary factor affecting this  downward migration is the kinematic
viscosity of the product, or its resistance to flow.  A product with a;
relat vely low kinematic viscosity, such  as gasoline, kerosene, or fuel oil
No. 1  is lik&ly to move through the unsaturated .zone much more quickly than a
product with'a relatively high kinematic  viscosity, such as fuel oil No. 5 or
No. 6.

    Some or all of the released product may cling to the soil or rock
particles during the downward migration of released product.  This process,
known as adsorption, is particularly extensive with the. heavier fuel oils.
Even within a specific product, however,  the lighter constituents tend to move
farther and faster than the heavier components.  Heavier fuels also tend to be
be 'retained in the subsurface materials and trapped in the pore spaces rather
than being dispersed and diluted.  Thus,  the lighter fuels are likely to
contaminate a larger area than the heavier fuels.  On the other hand, the
tendency of the heavy fuels to be retained may result in greater
concentrations of contamination in an area.

4.2.2    Transport on Surface of the Water Table

    As released product travels downward  through the.unsaturated zone, it
passes through areas of increasing water  saturation.  Eventually, it reaches
the water table, which marks the boundary between the saturated and
unsaturated zones (Exhibit 4-2).  Because motor fuels and most heating oils
are less dense than water, they tend to spread out on top of the water table.
As increasing amounts of the release reach the water table, the flow spreads
out, forming a free product plume with the general shape of a pancake (CDM
1986).  An example that illustrates the spread of a released product is an
                                     4-4

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                                      Exhibit 4-2

                      Schematic of Subsurface Environment
                            /' „ , S, •... ,' s ' ,  /' ,  ' , • ,   ,/,'
                               Water Soluble Fraction
                                                                           Saturated
                                                                             Zone  •
                                                                            (Aquifer)

/^<^/^/^<^/^<^^

                                                             IMPERMEABLE BOUNDARY
 Source: ICF Incorporated analysis.

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incident in Saint Paul, Minnesota, that involved a release of 4,000 gallons of
fuel oil No. 4.  Soil borings indicated a plume floating on the water table
ranging from 60 to 100 feet in diameter and from 13 to 20 feet deep (ICF
1988b).

    Fluctuations in the water table may force previously adsorbed constituents
to become mobile again and become part of a migrating plume.  Thus, motor
fuels and fuel oils that are retained in the soil and rock matrix will be a
continuing source of contamination long after initial corrective actions are
taken' (Kemblowski et al. 1987, Baradat et al. 1981).  In another Minnesota
release incident, changes in the. ground-water table led to the discovery of
additional contamination in the subsurface soil long after remediation was
thought to have removed the contamination (ICF 1988b).                  ,

4.2.3    Transport: in the Saturated Zone

    In addition to the plume of contaminants that floats on the surface of the
water table, a portion of the plume (the water soluble fraction shown in
Exhibit 4-2) will mix with the ground water and move along the main direction
of ground-water flow.  In general, gasoline and the lighter heating oils
contain greater concentrations of soluble constituents than the heavier
heating oils and are, therefore, likely to be transported farther in the
saturated zone.  Fuel oil Nos. 5 and 6 tend to have few constituents that are
water soluble (USEPA 1985b).                          _              '    ;

4.2.4    Transport: of Vapors

  .  Of the mc^or fuels and heating oils studied in this report, only the
lighter products, such as gasoline, kerosene, and fuel oil No.l, have
constituents that are likely to volatilize in substantial amounts.  The
heavier products (fuel oils Nos. 4, 5, and 6) generally do not have volatile
components that generate vapors easily transported in the soil. '

4.2.5    Fate Processes

    Several mechanisms will affect how long petroleum products will remain in
the subsurface environment and influence the hazard posed by a release.
Although dispersion and dilution do not destroy the released constituents,
these processes may reduce released concentrations to undetectable levels.
Adsorption to subsurface materials and retention in the pore spaces, however,
tend to oppose these processes and may trap the released product indefinitely.
Constituents may also be transferred to another medium,  such as volatilization
to air or release to surface water.  In addition, biodegradation (breakdown by
living organisms) may also help reduce contaminant levels, particularly for
the aromatic fraction of the fuels.  The heavier fuel oils are not as
biodegradable because of their large molecular sizes and low solubilities.

4.3  SUMMARY OF POTENTIAL RISKS TO HUMAN HKAT.TH AND THE ENVIRONMENT

    Many of the petroleum products stored in exempt heating oil and motor fuel
tank systems are known to contain probable human carcinogens and other
compounds harmful to human health; however, the exact concentrations of the
                                     4-6

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hazardous substances present are unknown.  Although the exact level of risk
posed by releases of these products is impossible to assess, relative risks
can be assigned based on the toxicity of the product and its constituents, and
the likelihood of the products to contaminate soil, air, surface water, and
ground water.

    •    Contaminated ground water is the most likely route to human exposure
         of products released from exempt tank systems.  Consumption of low
         levels of contaminants in ground water may occur for long periods .of
         time and probably represents the more significant threat to human
         health.  Higher levels of contamination are less of a problem because
         people are less likely to drink water that has a bad taste or smell.

    •    Gasoline is the most studied fuel stored in exempt tank systems^ •
         Gasoline is likely to travel faster in the soil than other products
         stored in exempt tank systems and is a probable human carcinogen.

    •    Qf the heating oils, the middle distillates, such as fuel oil No. 2.
         probably pose the greatest threat to human health.  These products
         are stored more frequently in exempt tank systems than are motor or
         residual fuels and, although slightly less mobile than gasoline, they
         are still likely to contaminate ground water.  In addition, low
         levels of probable human carcinogens have been detected in fuel oil
         No. 2.  The middle distillates also contain other substances known to
         have adverse health effects.

    •    ResidueL fuels, such as fuel oil No. 6. probably pose a smaller
         threat  o human health than-the middle distillates, but this  .hreat
         may still be significant.  Even though fuel oil No. 6.contains
         relatively high levels oฃ probable cancer-causing substances, it can
         be so viscous (thick) that it is unlikely to reach ground water in
         large quantities. However, under certain conditions, such as
         incidents when fuel oil No. 6 was released near a sewer line or into
         fractured bedrock, large amounts of contamination have occurred.
         Furthermore, although residual fuels are not as mobile as the middle
         distillates, they are difficult to clean up after a. release and are
         likely to persist in the environment longer than other fuels.
                                     4-7

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                  5.  STATE AND LOCAL-REGULATION OF EXEMPT
                   HEATING OIL AND MOTOR FUEL TANK SYSTEMS

     Many states and localities have already addressed the regulation of
exempt heating oil and motor fuel tank systems.   This section reviews the
status of state and local regulatory UST programs to determine if federally
exempt tank systems are regulated under their statutes.  Unless specifically
qualified in this section, the terms "exempt" and "regulated" refer f> federal
regulation under Subtitle I.

5.1  STATE REGULATIONS

     To assess the current level of state regulation of exempt heating oil and
motor fuel tank systems, statutes and regulations from 34 states were examined
and the tank systems exempt from regulation were identified (the remaining 16
states did not have an UST statute available for review).  This review of
state statutes and regulations revealed that at least 21 states currently
consider exempt tank systems to be a problem and have included them to some
extent in their regulatory framework.

     Of the 34 states reviewed:

     •    Twenty states have some regulations for exempt heating oil tank
          systems (panel 1 of Exhibit 5-1);

               Eighteen states have some regulations for residential heating
               oil tank systems, of which only eight regulate heating oil tank
               systems smaller than 1,100 gallons;

               Eighteen states have some regulations for farm heating oil tank
               systems;

               Seventeen states have some regulations .for nonresidential
               heating oil tank systems;                 :

     •    Ten states have some regulations for exempt motor fuel tank systems
          (panel 2 of Exhibit 5-1);                                ,

               Eight states have some regulations for residential motor fuel
               tank systems under 1,100 gallons;

               Eight states have some regulations for farm motor fuel tank
               systems under 1,100 gallons;

     •    Six states have some regulations for all exempt tank systems (panel
          3 of Exhibit 5-1); and

     •    Thirteen states regulate the same USTs as Subtitle I .(panel 4 of
          Exhibit 5-1).
                                     5-1

-------
     ta
     
-------
     Several states' regulations "mandate only notification/registration of the
existence of tank systems and the reporting of releases when they occur, but
do not mandate other technical!' standard!^ (such as material of construction and
leak detection).  Furthermore, many of the state regulations covering exempt
heating oil tank systems include only those tank systems with a capacity equal
to or greater than a specified size, most commonly 1,100 gallons.  A detailed
list of existing state statutes that were reviewed is provided in Exhibit 5-2,
at the end of this section.                             •

     State regulation of exempt tank systems was generally more extensive
where the greatest number of exempt tank systems are located.  For example,
all of the states in the Northeast, except Pennsylvania and Delaware, have
some regulations regarding exempt heating oil tank systems.  (Exempt heating
oil tank systems located in the Northeast comprise almost 50 percent of all
exempt tank systems.)                                                   .    ; •

     An assessment of the present level of state regulation of exempt tank
systems based on a review of state statutes and regulations must be qualified
by the following observations:

     •    A review of state statutes and regulations does not
          necessarily indicate the actual amount of regulatory          •'"'-."
          activity occurring.                                           ;.

               Statutes are usually just the first step toward         t>'
               developing a state regulatory program.  State
               and local regul..';ory agencies often have their
               own priorities ror allocatinf resources that             :.'..
 '              determine the level and scope of the regulatory
               program and enforcement that is undertaken.          • \~- •,
               Thus,, a statute may require regulation'of exempt   ;. • '•-.
               tank systems, but in practice a state .implement-.!
               ing agency may concentrate its limited resources
               on tanks regulated under Subtitle I;     ,: .;   ;

               A state program may be operating under the
               authority of a statute not specific to
               underground tanks (such as a general ground-
               water protection statute) and the program
               exemptions may not be defined in the statute.

     •    Many of the statutes and regulations reviewed are quickly     •  .
          becoming outdated because there is currently a                ; '•
          considerable amount of legislative activity concerning the
          regulation of USTs.  In July 198",  , there were 57 bills in
          29 state legislatures concerned with underground tanks
          (API 1987).

Discussions with five states indicated that many states appear to be waiting
to see whether Congress and EPA will address exempt tank systems before they
pass new legislation (ICF 1988b).
                                     5-3

-------
5.2  LOCAL REGULATIONS

     In addition to states, some local governments have developed UST
regulatory programs that include exempt tank systems in their regulated
community.  Four of the more developed UST programs reviewed include:  Dade
Co., Florida; Barns table Co., Massachusetts; Suffolk Co., New York; and
Austin, Texas.

     Of these four localities:

          •    Two have some regulations for all exempt tank systems;

          •    Two have some regulations for some exempt tank systems;

                    One has some regulations for all nonresidential exempt
                    tank systems; and

                    One has some regulations for all exempt tank systems
                    except heating oil tank systems under 1,100 gallons.

     A detailed list of existing local statutes reviewed is provided on the
last page of Exhibit 5-2.                                  ,           •

5.3  SUMMARY

     This review of the status of   :ate and local regulatory UST programs
reveals that some areas of the coui.,cry already have sore regulations
pertaining to exempt tank systems.  The extent of regu! itions varies among
states and localities, with tank registration and notification of releases
being the most common requirements.  When technical standards are required for
tank systems, such as a prohibition against the installation of new corrodible
tank systems, or requirements for leak detection, they are generally limited
to large (frequently for those tanks with a storage capacity of 1,100-gallons
or more) nonresident ial heating oil facilities.  Residential •, farm, and
smaller nonresidential tank systems are frequently exempted from technical1
standards.  Legislative and regulatory activity is continuing in many states.
                                     5-4

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                                 REFERENCES
American Petroleum Institute (API).  1983.  Memorandum dated June 24,  1983,
from C. DiBona, President of API to members.  FYI submission from API  to Mr.
William Ruckleshaus, Administrator, U.S. EPA,  FYI-AX-0783-0148,  Supp.
Sequence H, July 15, 1983.  (As cited in USEPA 1985a).

American Petroleum Institute (API).  1985.  Unpublished information on the
production, use, exposure, and toxicity of petroleum residual fuels.  .-'•'•, • • .V
Submitted by S.M. Swanson, American Petroleum Institute.  February 28.   (As
cited in USEPA 1985b).

American Petroleum Institute (API).  1987.  Underground Storage Tank
Regulations.  July 10, 1987.

Baradat, Y., J.S. Lemlin, P. Sibra and H. Somerville.  1981.  A Review of the
Investigation of a Kerosene Spill at Strasbourg - Entzheim Airport, France.
CONCAWE, The Hague, Netherlands.

Barrientos, A., M. Ortuno, J. Morales, F. Tello and J.  Rodicio.  1977.   Acute
renal failure after use of diesel fuel as a shampoo.  Archives of Internal
Medicine'137:1217.  (As cited in Gosselin et al. 1984).
'  •    '                                           S
California State Water Resources Control Bosrd.  1986.   UST i otification Data
Base.  December 1986.

Camp, Dresser, and McKee Inc. (CDM).  1986.  Interim Report:  Fate and
Transport of Substances Leaking from Underground Storage Tanks, Volume 1 -
Technical Report.  Prepared for Office of Underground Storage Tanks, EPA,
under Contract No. 68-01-6939.  Camp, Dresser, and McKee, Boston, MA.

Connecticut Department of Environmental Protection (CDEP).  1986.  Personal
communication with Carmine di Battista by SCS Engineers in December 1986.

Crisp, A., A. Bhalla and B. Hoffbrand.  1979.  Acute tubular necrosis  after  .
exposure to diesel oil.  British Medical Journal 2:177-178.  (As cited in
Gosselin et al. 1984).

GCA Corporation.  1983.  Sample of virgin fuel oil from suburban Philadelphia.
October 28, 1983.  (As cited in CDM 1986).

ICF Incorporated.  1987.  Summary Notes of Meeting with New York Department  of
Environmental Conservation.  Prepared for Office of Underground Storage Tanks,
EPA.  December 28, 1987.

ICF Incorporated.  1988a.  Draft RIA for UST Technical Standard Regulations.
Prepared for Office of Underground Storage Tanks, EPA.   February 1988.
                                     R-l

-------
 ICF Incorporated.   1988b.   Summary Notes of December 2,  1987 Meeting with
 State and Local Officials  Concerning Federally Exempt Underground Storage
 Tanks.   Prepared for Office of Underground Storage Tanks,  EPA.   January 1988.

 ICF Incorporated.   1988c.   Trip Report on Interviews of Maryland Officials
 Regarding Federally Exempt Underground Storage Tanks.  Prepared for Office of
 Underground Storage Tanks, EPA.  January 21, 1988.

• Interaatic lal Agency For Research on Cancer (IARC) .   1983.   IARC Monographs on
 the Evaluation of the Carcinogenic Risk of Chemicals to Humans.   Vol. 32:
 Polynuclear Aromatic Compounds; Fart 1, Chemical,  environmental and
 experimental data.  World  Health Organization, Lyon, France.
                                                                         •*  ''. ' '
 International Agency For Research on Cancer (IARC).   1984.   IARC Monographs on
 the Evaluation of the Carcinogenic Risk of Chemicals to Humans.   Vol. 33:
 Polynuclear Aromatic Compounds; Fart 2, Carbon blacks, mineral  oils and some
 nitroarenes.  World Health Organization, Lyon, France.

 Kansas Department of Health and Environment (KDHE).   1986.   Personal
 communication with Marvin  W. Glotzbach by SCS Engineers in December 1986.

 Kemblowski,  M.W.,  J.P.  Salanitro, G.M. Dealey and C.C. Stanley.   1987.   Fate
 and transport of residual  hydrocarbon in groundwater - A case study -   :.
 Abstract.  Presented at Petroleum Hydrocarbons and Organic Chemicals in. Ground
 Water:  Prevention, Detection, and Restoration.  Houston, TX. November 17.-19,
 1987.

 Maine Department of Environmental Protection.  1986.  UST  Notification Data
 Baset  Dp-jember 1986.
'•                                 •                   "                 •**'•
 Massachusetts Department of Environmental Quality Engineering {MDEQE)/  1986.
 Personal communication with Deidre Doherty by SCS Engineers in  December 1986.

 Minnesota Pollution Control Agency (MPCA).  1986.   Personal communication with
 Thomas P. Clark by SCS Engineers in December 1986.      /   .

 Montana Department of Health and Environmental Science.  1987.   UST
 Notification Data Base. March 1987.

 National Petroleum Council.  1984.   Petroleum Inventories  and Storage
 Capacity: A Report of the  National Petroleum Council.  June 1984.

 New York State Department  of Environmental Conservation (NYSDEC).  1987a.'";
 Personal communication with Morris Leno, NYSDEC.

 New York State Department  of Environmental Conservation (NYSDEC).  1987b.
 Personal communication with Joseph McDonald, NYSDEC.

 North Carolina Department  of Natural Resources and Community Development
 (NCDNRCD).  1986.  Personal communication with Lee Layman,  NCDNRCD,  by SCS
 Engineers in December 1986.
                                      R-2

-------
Oil Heat Task Force.- 1987^ -Comments to5the Office of Underground Storage
Tanks, EPA, on its Contractor Draft "Study of the U.S. Population of USTs
Exempted under Subtitle I of RCRA."  September 30, 1987.

Pancirov, R. and R. Brown.  1975.  Analytical methods for polynuclear aromatic
hydrocarbons in crude oils, heating oils and marine tissues.  Pages 103-113 in
Conference on Prevention and Control of Oil Pollution.  San Francisco, CA.

Petroleum Marketers Association of America (PMAA).  1987.  Comments on Draft
Study-of Heating Fuel Tank and Motor Fuel Tank Exempt from EPA Regulations.
September 23, 1987.             .                                           '

Pirn, J.  1987.  Interim Report II, Tank Corrosion Study.   Prepared for Office
of Underground Storage Tanks, EPA, by Suffolk County Department of Health
Services, NY.  November 1987.

Pirn, J.  1988.  Interim Report III, Tank Corrosion Study- Federally Exempt
Tanks.  Prepared for Office of Underground Storage Tanks, EPA.  Prepared by
Suffolk County Department of Health Services, NY.  February 1988.

Steel Tank Institute (STI).  1986.  Personal communication with Wayne Geyer,
STI, by SCS Engineers of November 12, 1986.

Tomkins, B. and W. Griest.  1987.  Liquid chromatographic determination, of
benzo(a)pyrene at part per billion concentrations in highly refined coal and
petroleum derived fuels.  Journal of Chromatography 386:103-1120.

U.S. Department of 'griculture.  Unpublished data.'  1985 Farm Cof.ts and
Returns Survey.  Na ional Agricultural Statistics Services, Washington, DC.

U.S. Department of Energy.  1985.  Non-residential Buildings Energy
Consumption Survey: Characteristics of Commercial Buildings 1983.  July 1985.
Energy Information Administration, Washington, DC.

U.S. Environmental Protection Agency (USEPA).  1982.  An .Exposure and Risk
Assessment for Benzo(a)pyrene and the Polycyclic Aromatic Hydrocarbons:
Volume II-Naphthalene (Final Draft Report).  WH-553.  Office of Water
Regulations and Standards, Washington, DC.

U.S. Environmental Protection Agency (USEPA).  1985a.  Information Review of
Unleaded Gasoline (Draft Report).  Prepared under EPA Contract No. 68-01-6650.
IR-469.  February 8, 1985.  TSCA Interagency Testing Committee, Washington,
DC.

U.S. Environmental Protection Agency (USEPA).  1985b.  Information Review of
Residual Fuel Oils (Draft Report).  Prepared under EPA Contract No. 68-01-
6650.  IR-471.  April 19, 1985.  TSCA Interagency Testing Committee,
Washington, DC.
                                     R-3

-------
U.S. Environmental Protection Agency  (USEPA).  1985c.  Information Review of
Petroleum Middle Distillate Fuels  (Draft Report).  Prepared under EPA Contract
No. 68-01-6650.  IR-470.  March 15, 1985.  TSCA  Interagency Testing Committee,
Washington, DC.                                                       •

U.S. Environmental Protection Agency  (USEPA).  1985d.  Health and
Environmental Effects Profile for  Phenol.  Errata, 1986.  Prepared for the
Office of Solid Waste and Emergency Response, EPA.  Environmental Criteria and
Assessment Office, Cincinnati, OH.
U.S. Environmental Protection Agency (USEPA).
Storage Tanks: A National Survey.  May 1986.
Substances, Washington, DC.
 1986a.  Underground Motor Fuel
Office of Pesticides and Toxic
U.S. Environmental Protection Agency (USEPA).  1986b.  Superfund Public Health
Evaluation Manual.  Office of Emergency and Remedial Response, Washington,  DC.

U.S. Environmental Protection Agency (USEPA).  1987.  Notes of the July 8th,
1987 Meeting with PEI Installers at Dallas/Fort Worth Airport.  July 15, 1987.
Office of Underground Storage Tanks, Washington, DC.
                                     R-4

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TECHNICAL APPENDICES

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                                  APPENDIX A

  DETERMINATION OF POPULATION SIZE AND CHARACTERISTICS OF EXEMPT TANK SYSTEMS
     This  technical  appendix  supports  Section 2, Description of Exempt Heating
;0il  and Motor  Fuel  Tank Systems,  by  presenting the informatio  and
 methodology used to derive the estimates of the population size, location, and
 other  characteristics  of exempt tank  systems.  Sections A.I and A.2 describe
 the  estimates  of population  size of exempt heating oil and motor fuel tank
 systems,  respectively.   These sections contain information regarding:   '•>•'" '•'•'

          m   Data sources,

          •   Computational methods,

          •   Input data and results, and

          •   Assumptions and  sources of error.

 Section A.3 describes  the information used to support Section 2.3,
 characteristics  of  Exempt Tank Systems.
                               •                              i           •
 A.I  EXEMPT EliTING OIL TANK SYSTEMS
                                                 fs.
     Section A.I  is  divided into three sections.  Sections A.I 1 and A.1.2
 provide documentation  of the estimates of the residential and farm heating oil
 sectors,  respectively.   Section A.1.3 describes the estimates for the three
 subsectors  that  combine to form the nonresidential sector.

 A.1.1   Residential  Heating Oil Sector

     Exhibit A-l  shows  the derivation  of the estimate of exempt residential
 heating oil tank systems based on U.S. Census and Department .of Energy data.
 There  are an estimated 12,585,000 housing units in the U.S. heated with fuel
 oil  (total  in  column C of Exhibit A-l).  These housing units include
 facilities  that  use either aboveground or underground tanks.  A frequency
 distribution of  tank capacities is listed in column B.  The number of housing
 units  heated with fuel oil  (including both aboveground and underground tanks)
 is shown  in column  C and is  estimated for each tank size category by
 multiplying the  number of housing units  (12,585,000) by each of the relative
 frequencies in column  B. The estimated number of exempt heating oil
 underground tank systems (column E) is then determined by multiplying the
 estimated number of housing  units heated with fuel oil (column C) by the
 percentage  of  each  category  assumed to be buried underground (column D).
      •*• An exempt tank system includes a single  exempt  tank and its  associated
 piping.  See Appendix E for further elaboration of the definition.
                                      A-l

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                                 Exhibit A-l

                       ESTIMATE OF THE POPULATION SIZE
               OF EXEMPT RESIDENTIAL HEATING OIL TANK SYSTEMS
[A]
Tank
Capacity
(gallons)
< 249
250-300
301-799
> 800
Not Paying
for Oild
1 Total
[ป]
Frequency ( % ) a
7.6
48.3
14.5
4.8
24.8
100.0
[C]
Housing Units
Heated with
Fuel Oilb
956,000
6,079,000
1,825,000
604*. 000
3,121,000
12,585,000
[D]
Frequency (%)
of Under-
ground Tanksc
0
5
40
95 .
-_ e
-7 I
[E]
Number of
Exempt ; r.
Tank Systems
0
304,000
730,000
574,000 .•
253,000
,861,000.;

     a Includes both aboveground and underground tanks. . Source:   U.S.
Department of Energy (1982).

     " Source:  U.S. Dept. of Commerce (Bureau of Census) and U.S. Dept.  of
Housing and Urban Development (1985).

     c Source:  SCS Engineers (see Exhibit A-4 for specific sources),
Petroleum Marketers Association of America (1987), and Oil Heat Task Force
(1987).                          ,      '                                  ';';

     d Based on the individuals who responded to the census that they did not
pay for their oil (and, consequently, did not know the size of the tank).
These were assumed to be multiple-family residences.

     e See Exhibit A-2 for detail on this category and derivation of the
number of exempt tank systems at multiple-family residences.
                                     A-2

-------
    The estimate for the number of the underground heating oil tank systems
serving the 3,121,000 multiple,-family housing units is derived in Exhibit A-2.
The number of housing units heated with fuel oil is given in column C and is
determined by multiplying the number of multiple-family housing units heated
with fuel oil (3,121,000, from column C of Exhibit A-l) by the frequency of
four sizes of multi-unit structures (column B).   The number of exempt tank
systems in each size category (column F) is determined by dividing the number
of housing units heated with fuel oil, column C, by the number of housing
units per heating oil tank, column D and malitplying by the percentage in each
category that is assumed to be buried, column E.

    The geographic location of exempt residential heating oil tank systems was
calculated in the same manner as the national population estimates.  The total
number of housing units heated with fuel oil in the U.S. (12,585,000, the
total of column C of Exhibit A-l) was replaced with each of the regional
numbers of housing units (column A of Exhibit A-3).  The resulting regional
estimates are included in column B of Exhibit A-3.

    The major assumptions for these estimates are a source of potential error
in the determination of the size of the entire population of exempt tank
systems because of the large proportion of exempt tank systems which fall into
this category.  The major assumptions and potential sources of error are:  -

    •    Expert opinions.  The percentage of heating oil tanks believed to be
         buried underground (for each tank size  group and for each group of
         multi-family housing unit size) are expert opinions, as are estimates
         for the number of housing units per tank'in the multiple-family
         residential estimate (see Exhibit A-4).

    •    Double Tank Systems.  Heating oil storage systems (either aboveground
         or underground) using two or more small tanks for storage capacity
         may be counted as a single larger tank system, which could reduce the
         number of tanks in the smaller size categories and increase the
         number of tanks in larger size categories.  It is difficult to
         estimate the effect of this source of error on the final estimate,
         but it is believed to be small.

    •    Sampling error.  Sampling error associated with the census data
         occurs, because a total census or counting Cannot be performed due to
         limitations of time and funding.


A. 1.2  Fara Heating Oil Sector

    The estimate of exempt farm heating oil tank systems, 43,000 tanks, is one
of the few use sectors that has direct survey data available.  This estimate
was obtained by adding a question regarding underground tanks to the U.S.
Department of Agriculture, National Agricultural Statistics Services' "1985
                                     A-3

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                                 Exhibit: A-2

                       ESTIMATE OF THE POPULATION SIZE
             OF EXEMPT MULTIPLE-FAMILY HEATING OIL TANK SYSTEMS
[A]
Housing
Units
Per
Facility
2-4
5-9
10-19
> 20
[B]
Frequency
(%)a
31.0
12.0
12.1
44.9
[C]
Housing
Units
Heated With
Fuel Oil
967,500
374,500
378,000
1,401,000
[D]
Number of
Housing Units
Per Heating
Oil Tankb
2
3
15
25
[E]
Frequency (%)
of Under-
ground Tanks0
15
80
95
100
[F]
Number of
Exempt Tanks
73,000
100,000
24,000
56,000
 Total
100.0
3,121,000C
253,000
     a Source:  U.S. Dept. of Commerce (Bureau of Census) and U.S.  Dept.  of
Housing and Urban Development (1985).

     ฐ Source: Includes both aboveground and underground tanks,  SCS Engineers
(see Exhibit A-4 for specific sources).

     c Source:  SCS Engineers (see Exhibit A-4 for specific sources),
Petroleum Marketers Association of America (1987) , and Oil Heat Task Force
(1987).

     d  From Column C of Exhibit A-l.
                                     A-4

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                                 Exhibit A-3

                    ESTIMATES OF THE GEOGRAPHIC LOCATION
          OF EXEMPT UNDERGROUND RESIDENTIAL HEATING OIL TANK SYSTEMS
   Geographic
    Region3
    [A]

Housing Units
 Heated with
  Fuel Oilb
                                                           [B]
Number of Exempt
 Tank Systems0
 Northeast

 North Central

 South

;West


 TOTAL
 8,089,000

 1,761,000

 2,272,000

   463,000


12,:J35,000
  1,196,000

    260,500

    336,000

     68,500


  1,861,000
      a See Exhibit 2-2 (page 2-5)  for maps depicting geographic regions.  '"

      k Source:   U.S.  Dept.  of Commerce (Bureau of Census)  and U.S.  Dept.  of
 Housing and Urban Development (1985).

      c Regional estimates of the number of exempt tank systems were calculated
 using the same  methods as Exhibit  A-l, except regional data on the  number of
 housing units (column A of this exhibit) were used in column C of Exhibit A-l.
                                      A-5

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                                  Exhibit A-4

      LIST OF CONTACTS FOR SCS ENGINEERS' STORAGE TANK INSTALLERS SURVEY

     Representatives  from the companies  and  agencies  listed below were
 contacted by telephone  during December,  1986,  and January, 1987, by SCS
 Engineers for estimations of the percentage of heating oil tanks that are
•buried underground at single-family and multi-family residences, as well as
 estimates of the  number of multi-family housing units served per heating oil
 tank.

 Tank Installers:
                                                                        j

     Brennan Oil and  Heating  Company,  Incorporated; North Providence, RI
     Charles Plumbing and Heating;  Liverpool, NY
     Charlie's Oil Company, Incorporated; Fall  River, MA
     Gill Services; Warwick,  RI
     Jim Trembly Plumbing and Heating; Manchester, NH
     Oil Heat and  Engineering,  Incorporated;  West Hartford, CT
     Onondaga Heating; Syracuse,  NY
     Pittston Petroleum,  Incorporated; Glastoribury, CT
     Robert  Shreve Fuel  Company;  Arlington,  VA
     Southern States  Cooperative  Incorporated;  Chantilly, VA
     Star Petroleum Company;  Boston,  MA
     State Line Oil;  Grariby,  CT
     Supreme Fuel  Company; Quincy,  MA
     The Plumbing  and Heating Repair Company; Manchester, NH           ,
     Topar LP Oil  Company; Fairfield,  CT

 Government  Agencies:

     Barnstable County Health and Environmental Department; Barnstable, MA
     Connecticut Department of Environmental Protection; Hartford, CT
     Kansas  Department of Health  and Environment; Topeka, KS
     Minnesota Pollution Control  Agency;  St.  Paul, MN        :
                                     A-6

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Farm Costs and Returns Survey;.",  Not only, did survey respondents indicate the
presence of .a tank, but also whether the tank was underground.  The survey
also provided regional estimates for underground farm heating oil tank
systems.

    The U.S. Department of Agriculture defines a farm as any place from which
$1,000 or more of agricultural products were sold or normally would have been
sold during the 1985 census year.  These include farming, ranching, and .
related activities conducted by individuals, partnerships, corporations,
cooperatives, prisons, hospitals, grazing associations, and Indian
reservations.                   -

    Major potential sources of error include:                           '•','••••'.'

    •    Sampling error.  The Farm Costs and Returns Survey provides 80
         percent confidence boundaries with its weighted results.  Sampling
         error occurs because a total census or counting cannot be performed
         due to limitations of time and funding.

    •    Possible Overlap with the Residential Estimate.  It is possible that
         survey respondents may also have been considered in the residential
         estimate.  The USDA Farm Costs and Returns Survey reports that there
         were 1.5 million farms.  Resident owners/operators occupy 1.2 million
         of these farms.  It is likely that some portion of these individuals
         may have reported their underground tank systems as being located at
         both farms and residences.  The effects of the potential overlap
         between farms and residences on the estimate of the total exempt tank
         systems is minimal, however, brcause the entire farm heating oil
         estimate comprises only 1.4 percent of the.entire population, of
         exempt tank systems.


A.1.3  Nonresidential Heating Oil Sector

    The number of underground nonresidential heating oil tank systems was
determined by adding estimates for three subsectors: commercial,
institutional, and government; manufacturing; and military.  Methods used for
each of these subsectors are described below.

Comnercial, Institutional, and Goverment Heating Oil Subsector

    Exhibit A-5 shows the derivation of the estimated number of commercial,
institutional, and government heating oil tank systems.  The number of heating
oil tank systems at commercial, institutional, and government buildings, by
the size of the floor space in the building, is presented in columns A and B
of Exhibit A-5.  The number of tank systems (including aboveground and
underground) for each size category is determined by multiplying the number of
tank systems (column B) by the frequency of tank size (column D).  This result
is then multiplied by the estimated percentage of each group that is buried
underground (column E) to estimate the number of underground tanks (column F).
The weighted mean percentage for the probability of tank burial for all
                                     A-7

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                                 Exhibit A-5

         ESTIMATES OF THE POPULATION SIZE OF TJNDERGROUND COMMERCIAL,
           INSTITUTIONAL, AND GOVERNMENT HEATING OIL TANK SYSTEMS
[A]
Building
Size
(Sq. Ft)
5000 or less


•
5001 to 10,000

.a


Over 10,000
Total
[B] [C]
Number of Tank Size
Tank (Midpoint
Systems0 of grouping)
300,000 275
550
1000
2000
165,000 275
350
1000
- . 2000
5000
269,000 All sizes
733,000
Overall percentage of burial -
[D] [E]
Frequency Frequency of
Distribution3 Tank Burialb
35 5
30 40
25 95
10 95
3 5
10 40
45 . , 95
37" • "''...,• : 95:", '•/•>
5 • ': ';.-;?'. ;':.V 95"\, •
100 . . 95
(539,772)/(733,000) - 73.6%d
i
. IF]
Number
Exempt
Tank
Systems
. 5,250
36,000
71,250
28,500
;• V ป' •
•••:;;;,;248
6,600
, .70,538
"' 57,998
7,838
255,550
539,772
t

     a Source:  SCS Engineers (see Exhibit A-3 for specific sources).     I

     b Source:  SCS Engineers (see Exhibit A-3 for specific sources),
Petroleum Marketers Association of America (1987), and Oil Heat Task Force
(1987).

     c Source: U.S. Department of Energy (1985).

     ** This figure is a weighted mean.
                                     A-8

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commercial, institutional, and government heating oil tank systems was
determined to be 73.6 percent.        "••-*-"..,    •

    The geographic location of exempt commercial, institutional, and
government tank systems was calculated in the same manner as the national
population estimate, except the total number of tank systems (column B .of
Exhibit A-5) was replaced with each of the regional numbers of tank systems.
A summary of the regional estimates is included, in Exhibit A-6.

    The major assumptions and sources of error associated with the estimate of
exempt commercial, institutional, and government heating oil tank systems are
as follows:

    •    Sampling Error.  Sampling error or lack of representativeness
         attributable to the Department of Energy's survey data.

    •    Potential Double Counting.  Possible overlap between those persons
         who use their residences for commercial purposes, potentially
         including the estimates in both the residential and commercial data.

    •    Expert Opinions.  Expert opinions are used to estimate the frequency
         distribution of tanks, based on tank size, that are believed-to be
         buried underground.

    •    Double Tank Systems.  IJeating oil storage systems (either abpveground
         or underground) using two or more small tanks for storage capacity
         may be counted as a single ^Larger ฃank, which could reduce the number
         of tan'-.s in the smaller size categories 'and increase the number of
         tanks  n larger size categories.  It is difficult ttt estimate the
         effect of this source of error on the final estimate, but it is
         believed to be small.
Manufacturing Heating Oil Subsector                    .      .

    The estimate of the number of exempt heating oil tank systems located at  .
manufacturing facilities was calculated from the total storage tank capacity
for heating fuels consumed on premises (2,562,000,000 gallons; National
Petroleum Council 1984) and estimates for the average tank size.  The average
tank size at industrial facilities from three state notification data bases
was approximately 10,000 gallons (California- 15,000; Maine- 7,000; and
Minnesota- 10,000).  The estimate of the number of heating oil tank systems
was calculated by dividing the total storage capacity by the average tank size
[(2,562,000,000 galIons)/(10,000 gallons per tank) - 256,200 tanks].  The
number of these tank systems that are buried underground was calculated by
multiplying the number of tank systems times the probability of their being
buried.  This probability was assumed to be 73.6 percent, the same as the mean
probability estimated for the commercial, institutional, and government sector
(see Exhibit A-5).  This resulted in an estimate of 189,000 exempt
manufacturing heating oil tank systems in the U.S.
                                     A-9

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                           Exhibit A-6

             ESTIMATES OF THE GEOGRAPHIC LOCATION OF EXEMPT
COMMERCIAL, INSTITUTIONAL,  AND GOVERNMENT HEATING OIL TANK SYSTEMS


Region
Northeast
North Central
South
West
TOTAL
[A]
Number of
Heating Oil Tank
Systems3
(all sizes')
318,000
129,000
236,000
50,000
733,000
[B]

Number of
Exempt Tank
Systems
234,000
95,000
174,000
37,000
540,000
   Source: U.S. Department of Energy   (1985)
                               A-10

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     No data were available to'directly estimate the regional storage capacity
 of heating oils at manufacturing facilities;  however,  data were available
 regarding regional consumption of heating oils  at these facilities.   The
 geographic location of exempt manufacturing heating oil tanks was estimated by
 multiplying the estimated number of exempt tank systems for this use sector--
 189,000-- by the relative amount (%) of heating oil consumed at manufacturing
 facilities in each region.   The relative consumption of heating oils at
 manufacturing facilities, by region, was:   43.4 percent in the Northeast, 12.0
•percent in the North Central,  34.8 percent in the South,  and 9.8 percent in
 the West (U.S. Department of Commerce 1985).  This resulted in an estimated
 82,000 exempt heating oil tank systems in the Northeast;  66,000 in the South;
 23,000 in the North Central,  and 18,000 in the  West.

     The major assumptions and sources of error  for estimating the number of ;
 exempt manufacturing heating oil tanks are:

     •    Estimate of Probability of Burial.   The estimate of the probability
          of burial is the same as that used for the commercial, institutional,
          and government sector.  It is possible that the percentage of tanks
          buried in the manufacturing sector is  higher than 73.6 because of the
          generally larger tanks found at manufacturing facilities.  (Larger
          tanks are more likely to be buried than smaller tanks).  However, a
          100 percent assumed rate of burial for this sector, would add only
          67,200 tank systems to the estimate, which constitutes only 2;2:!;'.
          percent of the estimated 3.1 million exempt tank systems.  ,  V."?5

     •    Average Tank Size.   The estimate of  average-heating oil tank capacity
          was applied uniformly acres • the U.S.  based on data from three
.  .        states. -.                               •'..._       ;-.y •'.'-

     •    APPlieability of Consumption Data.   The regional total storage•
          capacity was assumed to be proportional to regional consumption of
          fuel oil.                      •          •  .  •  •;':r,'.. • '.,.••-.'.• - •        --.   '

     •    Sampling Error.  No sampling or other  error estimates have been
          published regarding consumption or storage, of heating oil.


 Military Heating Oil Subsector

     There are no calculations or quantitative. discussions involved in the •••.
 estimate of exempt heating oil tank systems for the military.  All the   ,;~r'
 information regarding this subsector is based on undocumented reports froinf the
 four branches of the military servi-ies.  In most cases, the numbers reported
 were given as minimum estimates.  Exhibit A-7 contains a summary of the
 information reported by the military services.

 A.2  EXEMPT MOTOR FUEL TANK SYSTEMS

     Section A.2 contains information regarding  the estimates of exempt motor
 fuel tank systems.  Section A.2.1 describes exempt farm motor fuel tank
 systems.  Section A.2.2 describes exempt residential motor fuel tank systems.
                                     A-ll

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                                 Exhibit: A-7
                   REPORTS OF EXEMPT MILITARY TANK SYSTEMS
                     USED TO HEAT RESIDENTIAL BUILDINGS
    Branch


   Army

   Navy

   Air Force

   Marines



   Total
 Reported Number
 Exempt Heating
Oil Tank Systemsa

       20,000

       10,000

       12,200

            0
       42,200
  Comments3
Reported as a minimum

Ranges from 6,000-14,000

Reported as a minimum

Claim to have removed
all exempt heating
oil tanks
     a Source:  Interviews conducted by SCS Engineers with representatives  of
each branch of the armed services (USA 1986; USN 1986; USAF 1986;  USMC 1986).
                                     A-12

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A.2.1  Fam Motor Fuel Sector
    The number of exempt farm motor fuel tank systems was estimated as the
average of estimates from two separate surveys:  the 1985 Farm Costs and
Returns Survey (U.S. Department of Agriculture unpublished data) and the Motor
Fuels Storage Tanks Survey (USEPA 1986a).

    The 1985 Farm Costs and Returns Survey is discussed in Section A.I.2 of
this appendix.  For the second estimate, from "Underground Motor Fuels Storage
Tanks: A National Survey," the authors of the report acknowledge that the
statistical design was optimized to produce the best estimate of commercial
motor fuel USTs (which tend to be most concentrated in urban areas).
Consequently, the experimental design used was sub-optimal for estimating the
number of exempt farm motor fuel tank systems (which tend to be located in
rural areas).  Such a design, however, is not expected to create a
statistically biased point estimate, but would likely increase the variance
around the point estimate.  Therefore, this estimate was also used for this
study.

    Estimates of the geographic location of exempt farm motor fuel tank
systems were available only from the 1985 Farm Costs and Returns Survey. The
regional distribution of these tank systems was determined by multiplying the
regional distribution percentage of exempt farm motor fuel tank systems from
the 1985 Farm Costs and Returns Survey by the estimate for this entire sector
(260,000 USTs).  The regional distribution was as follows: Northeast, 10.6
percent; North Central, 38.4 percent; South, 14.5 percent; and West, 36.5
pei ent.                                        .-/<^
                                                   i-
    Sources of error for the Farm Costs and Returns Survt/ are discussed in
section A.1.2 of this appendix.  For the EPA survey, sampling error associated
with the survey data occurs, because a total census or counting cannot be
performed due to limitations of time and funding.

A.2.2  Residential Motor Fuel Sector                     '

    The only data available on exempt residential motor fuel tank systems was
found in the state notification databases for California, Maine, and
Wisconsin.  A ratio of the number of exempt motor fuel tank systems registered
within each state to the number of housing units for that state was calculated
(column C of Exhibit A-8 is the quotient of column B divided by column A).-".
The weighted mean of these three ratios was used as the ratio of underground
motor fuel tanks to households for the country as a whole.  This mean was
multiplied by the number of housing units in the U.S. to estimate the entire
U.S. population of exempt residential motor fuel tank s; stems.  The data for
these calculations is presented in Exhibit A-8.              • '  -

A. 3  STATE UST NOTIFICATION DATA BASES

    Data from three state UST notification data bases (California, Maine, and
Montana) were used to analyze tank characteristics.  These states were
selected because of the limited availability of relevant data, rather than
based on statistical sampling techniques.  Furthermore, officials from each of
                                     A-13

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                                 Exhibit: A-8

                     ESTIMATED POPULATION SIZE OF EXEMPT
                     RESIDENTIAL MOTOR FUEL TANK SYSTEMS
                   [A]
            Number of Occupied
              Housing Unitsa
                          [B]

                    Number of Registered
                     Exempt Residential
                      Motor Fuel Tank
                         Systems*5
      [C]        .

      Ratio of
  Motor Fuel Tanks
to Housing Units
California
Maine
Wisconsin
9,675,000
431,000
1,748,000
2,097
323
9,989
0.00022
0.00075
0.00571
U.S. Total
87,489,000
            Weighted Meanc of the three State Ratios - 0.00105
                                                  . ' ' '       ' >        * l
       U.S. estimate' -.(Weighted Mean of Ratios) x  (Total U.S; Housing'Units)

                     -  .00105 x 87,489,000 - 91,900 ' :. ^:  : .  ..',.
     a Source: U.S. Department of Commerce  (1987).

     k Sources:  State UST Notification Data Bases from: California State ;
Water Resources Control Board, Dec. 1986; Maine Dept. of Environmei tal  .
Protection, Dec. 1986; and Wisconsin Dept.'of Industry, Labor, and
Human Relations, Feb. 1987.

     c The mean ratio is weighted by the number of occupied housing units per
state as a percentage of the total number of occupied housing units in
the three states considered.
                                     A-14

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these states acknowledge that the data- are not complete and that residential
and rural owners of small exempt tank systems (less than 1,000 gallons) are
the least likely to register their tank(s).

    Despite the lack of solid grounding based on statistical sampling theory,
the information available from analysis of tank characteristics of these three
data bases was used for describing exempt tank system characteristics and
comparing them with those of USTs regulated under Subtitle I.  The lack of
statistical sampling methods does not mean data are inaccurate or invalid -- •.
only that the degree of accuracy and validity are unknown.  UST program
officials from other states and localities were contacted to augment these   ;
data.                                                               -

    Exhibit A-9 summarizes exempt tank system registration data for
California, Maine, Montana, and Wisconsin.
                                     A-15

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                                 EXHIBIT A-9

           SUMMARY OF THE NUMBER OF REGISTERED EXEMPT TANK SYSTEMS
California . Maine
Underground Heating
Oil Tank Systems:
Residential 364 3,802
Agricultural 129 305
Nonresidential 688 5,810
Subtotal 1,181 9,919
Underground Mo cor Fuel
Tank Systeas:
Residential 2,097 323
Agricultural 2,097 834
Subtotal 22,021 1,157
Total Registered
Exeapt Tank Systeas 23,202 11,076
Total Regulated USTs 124 , 786 9 , 313
Montana Wisconsin
•• ' ' •
14,815
569
11,499
973 28,602
'" c
-- 9,989
30,078
4,737 40,067
5,710 68,669
10,401 63,052
Source:  State UST Notification Data Bases from:  California State Water
Resources Control Board, Dec. 1986; Maine Dept. of .Environmental Protection,
Dec. 1986; Montana Dept. of Health and Environmental Science,  March 1987;  and
Wisconsin Dept. of Industry, Labor, and Human Relations,  Feb.  1987.
                                    A-16

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                                  APPENDIX B

                SOURCES OF INFORMATION ABOUT EXTENT OF RELEASES
        This appendix contains descriptions of the major sources, of information
 used to document the extent of releases from exempt tank systems.

 EPA State and Local Release Incident Survey (National Data Base)

        This data base,  containing records from 1970 to 1985,  provides   .,,.;x
 information on more than 13,000 reported releases from both regulated USTs and
 exempt tank systems, making it the most comprehensive source  of information  ~
 currently available on releases from underground storage tanks.   Information
 is  provided on approximately 2,000 releases from exempt tank  systems, 500
 releases from USTs containing hazardous wastes,  and more than 10,000 releases
 from regulated USTs.  The information was collected primarily by visits to
 state offices to review case files, but in some states, the data were obtained
 by  telephone.  The information includes only those releases detected and
 reported to state or local agencies and is not a statistically  valid sample of
 tank releases or of all underground tank systems.  As a result,  it is not.
;possible to assess the overall accuracy or validity of the data, nor is ,|t
 possible to develop a quantitative measure of confidence.              : . •"

 Report on Release,  from Federally Exempt Heating Oil and'Motor  Fuel Tank,  .'
 Systems, in, Maryland                             •• •'               *'.

';.- :      In November 1987, representatives of EPA and ICF Incorporated ..*';/••
 interviewed officials from Maryland's Department of the Environment 'to obtain
 both qualitative and quantitative information relating to releases of heating
 oils and motor fuels from federally exempt tank systems/  The. information
 collected included 154 reports from Underground Leak Summary  Forms of tank :
 system failures from September 11, 1985, to August 25, 1987;  and 904 reports
 from Initial Oil Spill Report Data Forms of tank system failures from late
 1985 to August 31, 1987.  The two types of forms account for  a  total of 989
 distinct cases,

 New York State's Spill Response Data Base                           "

        Data from the New York State Department of Environmental Conservation
 (NYSDEC) spill response data base, compiled under the mandate of New York's
 Petroleum Bulk Storage and Navigation Regulations, contain considerable.   ;
 information on spills involving heating oil.  The data covers 15,597 spills
 recorded between October 1985 and September 1987.  Of the total, 3,551 spills
 (23 percent) involved fuel oil Nos. 2, 4, or 6.  A major limitation of the
 data, however, is that the spill reports do not indicate if the release was
 from an underground or an above ground tank.  Additional information about
 these spills was obtained through interviews with representatives of NYSDEC,
 Bureau of Spill Prevention and Response.  These interviews were conducted by
                                      B-l


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EPA and ICF Incorporated during November 1987.  The information was used to
augment data from the National Data Base and from Maryland.

Summary Notes of Meeting with State and Local Officials Concerning Federally
Eseapt Tank Systens                        ..

       On December 2, 1987, EPA's Office of Underground Storage Tanks held a
meeting of representatives of the UST programs in Connecticut, Maine,
Minnesota, Rhode Island, Wisconsin, Barnstable County (MA), and Suffolk County
(NY)..  The purpose of the meeting was to allow these state and local UST
program representatives to share, their experiences and data on federally
exempt tank systems.  The available information varied from program to
program, but included a limited number of descriptions of releases from exempt
tank systems and the environmental effects of those releases,  estimates of the
total numbers of releases and well contaminations from exempt tank systems,
and observations on the extent of exempt tank system releases from the farm ,
and residential sectors.  A pooling of the data from these sources was not
possible because of the varied data collection methodologies and release
reporting requirements.

Tank Corrosion Study in Suffolk County (NY)

       This study is a joint EPA/Suffolk County investigation of corrosion as
a cause of releases from underground steel tanks.  As existing tank systems
were removed for replacement or for other reasons, a contractor examined them
for evidence of corrosion or perforations.  The latest available draft interim
report for this study ^Pim 1988) presents an assessment of 89 federally exempt
tank systems removed irora February 1987 through January 1988.   The study
includes both exempt tank systems and regulated,'USTs that contained heating
oil and motor fuel.  The previous interim report (Pirn 1987) summarizes the
results of the first 200 tanks (including both exempt tank systems and
regulated USTs) removed for this study.
                                     B-2

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                            "'w   APPENDIX C

                      POTENTIAL  IMPACTS ON HUMAN HEALTH
           AND THE ENVIRONMENT FROM PRODUCTS RELEASED FROM EXEMPT
                   HEATING OIL AND MOTOR FUEL TANK SYSTEMS

       This appendix provides a more detailed assessment of the discussion in
Section 4 concerning the potential human health risks associated with the
release of petroleum products from exempt tank systems.   In assessing these
health risks, it is necessary to evaluate (1) the composition of the petroleum
products and the toxicities of their constituents, (2) how released products
may be transported through the environment to points of  human contact, and. .(3)
the adverse health effects that may result from exposure to these substances.
Section C.I describes the products found in exempt tank  systems and summarizes
the toxic effects that have been associated with the products and their
constituents; Section C.2 discusses the likely environmental transport and
fate of substances released from underground storage tank systems, and how
these releases may lead to contamination of air,  soil, surface water, and
ground water; and Section C.3 discusses the possible ways humans may come into
contact with released petroleum products, and the potential health risks
associated with these exposures.

C.I    DESCRIPTION OF MOTOR FUELS AND HEATING OILS AND THEIR POTENTIAL HEALTH
       EFFECTS

       The first step in Assessing potential health risks is to determine the
composition of the released products and the toxicities  of their constituents.
This is a difficult task for two reasons.  First, although it is known that
exempt tank systems are used to store a variety of petroleum products,
including gasoline, diesel fuel, and fuel oils Nos. 1, 2, 4, 5, and 6, the
exact compositions of these products are unknown.  It is possible, however, to
estimate likely compositions by analyzing the refining process and reviewing
available data of selected constituents.  Second, the toxicities of even the
known constituents are generally not well studied.  Most of the available
studies examine the effects resulting from skin contact  with undiluted fuels
rather than the effects resulting from eating and drinking very dilute fuels,
the most significant means of exposure for humans.  It is possible, however,
to review the toxicity information available for some of the constituents.
The description of the products, therefore, begins with a discussion of the
manufacture of petroleum products and some basic properties of hydrocarbons in
Section C.I.I., and continues with a discussion of the toxicities of the fuels
and some of their constituents in Section C.I.2.
C.I.I  Manufacture of Petroleum Products

       Crude petroleum is composed mainly of hydrocarbons (compounds
containing carbon and hydrogen) and small amounts of nitrogen, sulfur, oxygen,
and heavy metals.  Three major classes of hydrocarbons are present:  (1)
paraffins, which are straight or branched chains of carbon atoms, (2)
cycloparaffins, which are closed chain or "cyclic" saturated hydrocarbons, and
                                     C-l

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 (3) aromatics, which are  "cyclic"  unsaturated hydrocarbons.   Some  adverse
 health  effects have  been  associated with smaller paraffin compounds  and
 cycloparaffins;  the  aromatic compounds are generally regarded as the most
 significant  toxic  components of the fuel oils.

        In the manufacture of petroleum products, .the crude petroleum is
 distilled into several  refinery streams.   All of the streams  have  the  three
 classes of hydrocarbons present, but in different proportions.  The
 hy '.rocarbons distilling from a representative sample of crude oil  are  shown in
 Exnibit C-l.

        As the distillation process begins,  the more  volatile,  lower  molecular
 weight  hydrocarbons,  with lower boiling points,  distill first and  are  the,  ;.;
 precursors of gasoline.   These compounds are  predominately hydrocarbons
 containing 3 to  11 carbon atoms and tend to be mostly short-chain  paraffins
 and small cycloparaffins.  A lower proportion of aromatics are present, and
 most  of these have one  or two rings or "nuclei" (mononuclear  aromatic
 compounds, such  as benzene,  toluene, and xylene).

        The middle  range molecular  weight molecules,  with mid-level boiling
 points,  distill  next and  make up what is referred to as the middle distillate
 fraction, from which kerosene, diesel fuel, and fuel oil Nos.  1 and  2  are
 derived.  These  hydrocarbons contain predominantly 9 to 25 carbon  atoms and
 tend  to be mostly  longer-chain paraffins than those  found in  gasoline  and,,
 larger  cycloparaffins.  The  proportion of aromatics  is higher than in  gasoline
 and the compounds  present contain  more rings  or "nuclei" (polynuclear  aromatic
 hydrocarbons, PAHs).  That is.   the aromatic fraction of the middle distillates
 t-ป.nds to have a  lower percentage of single-ring compounds (e.g. , benzene) than
•gasoline and a higher percentage of multiple-ring compounds  (PAHs),  although
 not as  high  as the residual  fuels.             ...        ...

        Relatively  non-volatile, high molecular weight compounds with high
 boiling points remain at  the end of the distillation process.  .Fuel  oil Nos. .
 4,  5, and 6  come from this residual stock.  The hydrocarbons  making  up the
 residual fuels tend  to  be very large and complex.  The paraffins comprise less
 and less of  the  total hydrocarbons present, and the  concentrations of  large
 cycloparaffins and large  aromatics (PAHs) are high.   These fuels,  as a class,
 tend  to have a higher concentration of PAHs than either gasoline or  the middle
 distillates; compounds  containing  four and five rings or more are  not
 uncommon.

        The only  standardization requirements  for  the final fuel products  .
 concern their physical  properties.  In some cases, the distillate  fractions
 conform to the fuel  specifications outlined by American Society for  Testing
 and Materials without further modification, and are  used as "straight  run"
 fuels.   In others, the  fractions may undergo  additional processing,  such as
 further refining,  blending with one or more refinery streams,  or,  in some
 cases,  addition  of agents such as  anti-corrosion or  combustion-enhancing
 compounds.   Because  the composition of hydrocarbons  is different in  every
 crude oil and, consequently, in every distillation stream, and because many
 additive formulations are patented and new formulations are constantly being
 created, it  is virtually  impossible to identify all  constituent concentrations
                                      C-2

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JS
 
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in petroleum products.  The actual compositions of fuels fluctuate depending
on the source of the crude, the refining processes utilized, and the streams
blended to produce the final products.

C.I.2  Potential Health Effects Resulting from Exposure to Petroleum Products
       and Their Constituents                   •

       This section discusses health effects that may be associated with
exposures to the fuels -and their constituents.  A summary of these health
effects is shown in Exhibit C-2.  Information on specific constituents has
been cited, because toxicity data on the fuels as mixtures are often limited.
Representative concentrations for some of the constituents are shown in
Exhibit C-3.  Actual concentrations of these substances in the fuels can,
fluctuate dramatically.  Available health-based criteria (e.g, cancer potency
factors, reference doses, and maximum contaminant levels (HCLs)) for the
constituents are presented in Exhibit C-4.                     .

Gasoline

     Gasoline, which has been studied extensively study under EPA's RCRA
Subtitle I regulatory program, is already classified as a probable human
carcinogen (API 1983, USEPA 1985a, ICF 1988).  As a result, this discussion of
the toxicities of products stored in exempt tank systems focuses primarily on
heating oils, which account for most of the petroleum products stored in
exempt tank systems.

Middle Distillate Fuels

     Some members of xhe middle distillate fuel family (in particular, fuel
oil No. 2 and diesel fuel) have been shown to be weak to moderate carcinogens
when applied to the skin of animals (USEPA 1985e) .   No studies examining
cancer effects following inhalation or ingestion were found (USEPA 1985e).
Non-cancer effects of the middle distillates include skin irritation and, at
high doses, hepatic toxicity (USEPA 1985e).  In humans, tubular necrosis was
reported in one adult who used diesel fuel to clean his hands and arms for
several weeks, and acute renal.failure was observed in another who used diesel
fuel as a shampoo (Crisp et al. 1979; Barrientos et al. 1977).

     Some of the compounds in the middle distillate fuels that may be of
toxicological concern are aromatic compounds, including noncarcinogenic PAHs,
such as naphthalene; other PAHs, such as benzo(a)anthracene and
benzo(a)pyrene, which have been shown to be carcinogenic in animals; and
cresols and phenols.  Three of the toxic aromatic constituents of gasoline,
namely toluene, xyle- e, and ethylbenzene, are also found in the middle
distillates, but are present in lower concentrations than in gasoline (Exhibit
C-3).
                                     C-4

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                            '^   Exhibit^ C-2

         POTENTIAL ADVERSE HEALTH EFFECTS ASSOCIATED WITH EXPOSURES
            TO SOME CONSTITUENTS OF MOTOR FUELS AND HEATING OILS
FUEL TYPE
CONSTITUENT
 POTENTIAL HEALTH EFFECTS
Gasoline
Benzene
Human carcinogen
Middle
Distillates

(Kero s ene, dies e1
fuel, fuel oil
Nos. 1 and 2, and
some blends of
No. 4)
Polynuclear aromatic
hydrocarbons (PAHs):

  naphthalene

  benzo(a)anthracene

  benzo(a)pyrene

Cresols and phenols
 Causes malaise,  tremors,
   vomiting,  and eye damage
 Probable human carcinogen   ;

 Probable human carcinogen
?                         •'-'"•'
 Irritates skin,  mucous membranes,
   and eyes
 May be cancer promoters
Residual
Fuels

(Fuel oil Nos.
5 and 6, and
most blends of
No. 4)
PAHs:

benzo(a)anthracene

benzo(a)pyrene

chrysene

Catalytically cracked
clarified oil
 Probable human carcinogen

 Probable human carcinogen

 May be a carcinogen


 Potent carcinogen in animals
Source:  Based on literature review performed by ICF Incorporated.
                                     C-5

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                               EXHIBIT C-3
                 CONCENTRATIONS  (G/L) OF SELECTED TOXIC
                      CONSTITUENTS OF HEATING .OILS
Constituent
Benzene
Toluene
Xylenes
Ethylbenzene
Phenol
Cresols
PAHs
Naphthalene
Benz o ( a) pyr ene
Benzo(e)pyrene
Benzo (a) anthracene
Phenanthrene
Fuel Oil No.2a Fuel Oil No.6b
BDL(O.l)
0.62
2.5
0.62
0.40
0.28
0.007
BDL(l.O)
* 0.054
2.5
2.7
0.0006
0.00003
BDL(l.O)
0.0001
0.001
BDL(l.O)
1.0
1.5
0.43-
c
c
c
d
c
d
d
c
d
c X 0.97 e
d
f 0.04 f
g
c •
f 0.01 f
f 0.09 f
c
c 0.46 f
d
f
Chrysene
   0.0014  f
BDL(l.O)   c
0.19
                                   C-6

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                                 EXHIBIT C-3
                    CONCENTRATIONS  (G/L)  OF SELECTED TOXIC
                         CONSTITUENTS OF  HEATING OILS

                                 (Continued)
Constituent
2 -Methylnapthalene

Pyrene


Fluoranthene


Heavy Metals
Arsenic
Lead
Fuel Oil No
7.0
6.7
BDL
0.041
BDL(l.O)
BDL
0.04
BDL(l.O)

0.003
0.001
.2a
c
d
d
f
c
d
f
c

h
h
Fuel Oil No. 6b
4.5 e

0.022 f


0.23 f



0.003 ' h
0.005 h
a Derived from weight percentages using 0.9 as Jhe s|tcific gravity of fuel
  oil No. 2.                                        .
b Derived from weight percentages using 1.0 as the specific gravity of fuel
  oil No. 6.                                        ....
c Oil Heat Task Force 1987.  Average of reported levels for three samples of
  fuel oil No. 2.  BDL indicates "below detection limit" and the instrument
  detection limits given in parentheses.  These samples are useful because =
  they provide an "upper-bound" concentration at which the constituent was
  not observed.
d Thomas 1984.  No detection limit given.  These samples are useful because
  they provide an "upper-bound" concentration at which the constituent was not
  observed.
e Neff and Anderson 1981.
f Pancirov and Brown 1975.
g Tomkins and Griest 1987.
h GCA 1983.
                                     C-7

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                                 EXHIBIT C-4

            HEALTH-BASED CRITERIA  FOR SELECTED TOXIC CONSTITUENTS
                       OF MOTOR FUELS AND HEATING OILS
•Constituent
                    Cancer Potency
                    Factor3-
                    (mg/kg-day) "-1
Reference      Maximum Contaminant
Doseb           Level0
(mg/kg/day)     (ug/1)
Benzene

Toluene

Xylenes

Ethylbenzene

Benzo(a)pyrene

Phenol

Arsenic

Lead
                       0.052  d
                      11.5
                      15.
   0.3 e

   2.0 f

   0.1 &



   0.04 i



   0.0014"
                     5.0
a  Cancer potency factors are used to estimate  excess; cancer  risks associated
   with lifetime exposures  to potential  carcinogens." ".-;!.  .
"  Reference doses are estimates  of the  level of daily exposure  that  is likely
   to be without appreciable risk of adverse effects.    , ';  •
c  MCLs are concentrations  that EPA has  set as  acceptable for public  water
   •supplies.
d  USEPA 1985b.
e  USEPA 1984a.
f  USEPA 1986c.                                                           .
5  USEPA 1985c.
^  This value  is currently  under  review.
i  USEPA 1985d.                                                          '<*
                                      C-8

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                                 .            ----.                 •.•
     Polynuclear *Toiปat:lc Hydrocarbons "f PAHs).  Several specific PAHs have
been detected in the middle distillates.  These include naphthalene,
benzo(a)anthracene, and benzo(a)pyrene (Exhibit C-3).  Health effects of these
PAHs are described below.  Because the concentrations of aromatic compounds
are so high in the residual fuels, it is likely that these compounds do not
represent all of the PAHs present.

     Naphthalene.  Naphthalene is present in significant concentrations in tine
middle distillates '(Exhibit C-3) .  This compound is toxic to humans by any
route of exposure.  There is no -evidence that naphthalene is carcinogenic;
noncancer effects following chronic ingestion or inhalation include malaise,
tremors, and vomiting  (IARC 1983;  1984).  Eye damage, such as injuries to the
cornea and opacities of the lens, may also occur (USEPA 1982).

     Benzo(a)anthracene and Benzo(a)pyrene.  Benzo(a)anthracene and
benzo(a)pyrene have been detected at very low concentrations in several
samples of fuel oil No. 2 (Tomkins and Griest 1987; Pancirov and Brown 1975).
Both of these compounds are classified as probable human carcinogens (USEPA
1986b).

     Cresols and Phenols.   Cresols are irritating to the skin, mucous
membranes, and eyes.   They can impair liver and kidney function, and can cause
central nervous system and cardiovascular disorders.  Phenol is toxic to the
liver and kidneys (USEPA 1985f).  Dermal applications of phenols and cresols
have been reported to  increase the number of skin tumors in mice when
administered after the application of cancer-causing a snts (Boutwell and
Bosch 1959; USEPA 1980).  Data are insufficient to asstsss the toxicity of
cresols by oral exposure (USEPA  1984b).               .


Residual Fuels

     The exceptionally viscous residual fraction of distilled petroleum is  -
often blended with less viscous  distillation streams so that, the final product
meets the performance  specifications designated for fuel oils Nos. 4, 5, and
6.  Blending agents include catalytically cracked clarified oil, catalytic
reformer fractionator  residue, straight run gas oil, heavy vacuum gas oil, and
heavy catalytically cracked distillate (USEPA 1986b).  While no reports
examining carcinogenic effects of the residual fuels were found, several
reports indicated that at least  two of the blending stocks used in their
production are carcinogenic in mice (USEPA 1985b, API 1985).  These blending
agents are cracked bunker fuel and catalytically cracked clarified oil.  The
latter is recognized as one of the most carcinogenic materials in petrolc im
refinery  (USEPA 1985b; API 1985). Noncancer health effects observed in animals
following oral administration of fuel oil No. 6 include lethargy and
intestinal irritation.  Chronic  dermal exposures can cause skin irritation
(USEPA 1985b).

     The constituents  of most concern in the residual fuels are the PAHs.
Although they are not  very water soluble, PAHs are present in higher
concentrations in residual fuels than in gasoline or the middle distillates.
                                     C-9

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     Polynuclear Axonatfc Hydrocarbons  (PAHs).  At least two of the PAHs,
namely benzo(a)pyrene and benzo(a)anthracene, that may be present in'fuel oil
No. 6 are classified as probable human  carcinogens.  There is limited evidence
that a third PAH, chrysene, is also carcinogenic in animals (IARC 1983).  PAHs
have a much higher concentration in residual fuels than in the middle
distillates.  In addition, because the  residual fuels tend to have high
concentrations of aromatic compounds, other.PAHs than the ones listed here are
likely to be present but have not been  reported.
                                                         ซ>
     Heavy aetals.  The heavy metals, such as arsenic, lead, and zinc, have
been detected at low concentrations in  samples of fuel oil Nos. 4 and 6 (GCA
1983).  Arsenic is a human carcinogen both by inhalation (lung cancer) and by
ingestion (skin cancer) (USEPA 1986b).

     In this section some of the known  toxic constituents of the fuels have  .
been discussed.  This discussion is not intended to imply that these are the
only toxic constituents present.  In fact, because little is known about these
fuels, it is likely that these constituents represent only a portion of the
hazardous components in these complex mixtures.


C.2  FATE AMD TRANSPORT OF RELEASED PETROLEUM PRODUCTS

     The adverse environmental and human health effects of products released
from exempt tank systems depend on how  long these contaminants are in the
environment and the extent to which they reach human or e.  Ironmental
receptors in harmful concentrations.  This section discuss :S factors that
affect how contaminants move in the environment and implications regarding the
overall hazard resulting from exempt tank systems,releases.

     The fate and transport of released petroleum products is affected by a
wide variety of site-specific and constituent-specific factors.  As a result,
conclusions that are generally true for petroleum releases may not be true for
all releases.  The major concerns, discussed below, are transport of free
product in the unsaturated zone (Section C.2.1), transport of free product; on
top of the ground water (Section C.2.2), transport of dissolved product in the
ground water (Section C.2.3), transport of vapors (Section C.2.4), and
processes that affect the fate of contaminants in the environment (Section
C.2.5).

C.2.1  Transport: of Free Product: in the Unsaturated Zone

General Discussion
                                                           *'•
     Transport of motor fuels and heating oils in the unsaturated zone of the
subsurface is characterized by a gravity-driven downward flow with some
lateral spreading of the plume because  of differences in soil permeability.  A
variety of physical and chemical properties of both the free product and the
environment into which it is released affect the movement of free product in
the unsaturated zone (i.e., above the water table).  The primary physical
properties of the products that affect  transport of petroleum contaminants
                                     C-10

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 released into the environment are the viscosity and density of the free
 product.  Physical characteristics of the subsurface that affect contaminant
 transport include adsorption of free product to the geological media of the
 unsaturated zone, permeability pf the media, the size of the pore spaces, and
 the degree of water saturation.  Major factors affecting the transport of  •
 released products in the unsaturated zone are summarized in Exhibit C-5.
 This section provides a brief description of each of these properties,
 followed by a discussion of the practical implication for the transport of
 products from exempt tank systems.                                        .

      The viscosity of a fluid is- a measure of its resistance to relative
 motion; the more viscous the fluid, the greater its resistance to flow.
 Gasoline is less viscous than water and, consequently, experiences less.J;-t:
 resistance to motion and can move more quickly through the unsaturated zone,-
 all other things being equal.  Heavier heating oils (e.g., fuel oil Nos. 4, 5,
 and 6) are substantially more viscous than water and tend to move much slower
 than water through the unsaturated zone.  The viscosity of petroleum products
 is usually expressed as kinematic viscosity, which is absolute viscosity
 divided by density.  Exhibit C-6 presents the kinematic viscosity for the
 petroleum products commonly stored in exempt tank systems.  As a basis for
 comparison, water has a kinematic viscosity of approximately 1 centistoke-.

      Density is the weight of a substance per unit volume.  A standard measure
; of density is specific gravity, which is the ratio of weight of a unit volume
 flf the free product compared to pure water.  Specific gravities for petrt>leum
 free products are given in Exhibit C-6.  Denser chemicals will travel downward
 through the unsaturated zone faster than less dense compounds. all other
 things beir.g equal. .                            ;

- ;  :   Released petroleum products do not flow unobstructed in the subsurface
 environment because xioristituents of motor fuels and heating oils adsorb to the
 particles of the subsurface matrix and are retained. .. Field studies indicate
 that sorption characteristics of subsurface geological -.materials and different
 hydrogeological settings will significantly affect the .retardation of the
 organic plume of contaminants as it moves through the subsurface (Mackay and
 Vogel 1985).  Clay and organic matter are especially good substrates for
 adsorption.  Many non-polar organic compounds, such as those that comprise the
 bulk of petroleum products, are likely to adsorb to the subsurface geological
 matrix.

      The tendency of chemicals to adsorb to the geological matrix is closely
 correlated to the tendency of chemicals to partition to the organic phase.when
 introduced to an aqueous/organic interface. The tendency to partition to the
 organic phase is measured by the Kow, the octanol/water partition coefficient.
 Log Kow values for petroleum free products are shown in Exhibit C-6; petroleum
 products have high Kow values and, therefore, have a strong tendency to adsorb
 to the geological matrix.  The tendency to adsorb is especially strong for the
 residual fuels, which have log Kow values ranging up to 6.  The large
 polynuclear aromatic hydrocarbons (PAHs) that are common in the residual fuel
 oils  (i.e., fuel oil Nos. 4, 5, and 6) contribute to this strong tendency to
 adsorb to soil particles.
                                      C-ll

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                                 Exhibit C-5

                          MAJOR FACTORS AFFECTING
                          TRANSPORT OF FREE PRODUCT
                           IN THF. UNSATDRATED ZONE
   FACTOR
 DEFINITION
 EFFECT
   Viscosity
   Adsorption
   Pore Size and
   Permeability
Resistance of
fluid to relative
motion.
Tendency of free
product to cling to
soil and geological
matrix.

Size of pores in
geological matrix and
ability of free product
to move through matrix.
Increases from
gasoline, which is
not viscous, to fuel
oil No. 6, which is
highly viscous and
tends not to flow.

Most petroleum free
product will adsorb to
particles, retarding
or inhibiting flow.

Free product moves more
easily through ma  :ix with
large pore spaces.  Small
pore sizes tend to retain
free product.
Source:  IGF Incorporated analysis.
                                     C-12

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                                                       EXHIBIT C-6

                                   PHYSICAL PHDPHBTIES OF 10108. FUELS AHD HEATIHG OILS
Boiling
Range*
Kinematic
Viscosity1*
(cST at 40ฐC)
Specific
Gravity3
Solubility
in Water
(ppn)
Log Octanol
/Water
Coefficient0
Vapor
Pressure0-
(ffliHg)
GASOLTHK
50-225
0.5-0,65e
0.72-0.768
130f
                                                                                   465-7738
Diesel Fuel

Kerosene

Fuel Oil No. 1

Fuel Oil No. 2
193-338

175-325h

193-293

282-338 '
1.3-24.0

1.0-1.91

1.3-2.1

1.9-3.4
0.81-0.90



0.81-0.85

0.88
10-100h



10-100k

 7-101
3-4.5



3-4.5

3-4.5
1-10

  903

1-10.;

1-10
Fuel Oil No.  4

Fuel Oil No.  5

Fuel Oil No.  6
101->588

218->570

212->588
5.5-24.0

>24-168

>92-638
(50ฐC)
0.90

0.94

0.97
 1-20ฐ

 1-20ฐ
3-6

3-6

3-6
  Weiss 1981
  ASTM 1986
  USEPA 1985g
  Rose and Cooper 1977; values for the middle distillates were measured at 38 degrees Centigrade and for the residual
  fuels at 71 degrees Centigrade.
  Speight WHO
  Brookman fct. al 1985a                                                        :
  ASTM 1980
  NIOSH 1977
  Goodger 1975
  Litton 1977                                                                           .
  Neff and Anderson 1981                                                           '         .
  Lu ปnd Polak 1973                           •                                                   '    .    •            .
  Kolpack et al 1973; Neff and Anderson 1981

                                                            C-13

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     The permeability of the geological material and pore size also has major
effects on the geometry of the release (i.e., the shape of the plume in the
unsaturated zone).  A highly permeable medium such as gravel or fractured rock
will allow a release to move rapidly through the medium.  In addition, the
plume will tend to disperse as it flows through the pores and around the
particles of the geological matrix.  Media with very small pore spaces, such
as clay, will severely impede the vertical flow of a release, causing the
plume to spread horizontally.                                       .

     As motor fuels and heating .oils migrate through a porous medium, a
certain amount will adsorb to geological material.  Adsorption of some of the
constituents in petroleum products is likely to be reversible.  Many of the
smaller and less hydrophobic compounds that adsorb to the geological materials
will desorb after the contamination is gone, providing a continuing source of
contamination after the source of the release has been removed.  This
phenomenon is especially likely to occur with the lighter aromatic fractions;
larger hydrocarbon chain compounds from petroleum products are expected to be
highly adsorbed to particles and will not desorb readily, if at all (USEPA
1985e).                                          .

     As the plume of contaminants approaches the water table, the degree of
water saturation in the vadose. (unsaturated) zone increases.  Because neither
motor fuels nor heating oils are very soluble, they cannot occupy the poฃe
spaces already occupied by the water.  Increasing water saturation will1;'.1.:..'
decrease the permeability of the unsaturated zone to the released product,
reducing the speed with which it reaches the water table, and incr^asin^ the
horizontal spread of the contaminant plume.     ./             '

     for immiscible substances (i.e., liquids that are insoluble in waiter)
such as fuel oils, the residual saturation of the free product', which 'is a
measure of the retentive capacity of the soil with .respect to a particular
free product, is an important factor in estimating its spread..  In general,
permeability and retentive capacity of a soil are inversely related:  less ,
permeable soils retain more of an immiscible substance than do more permeable
soils.  Consequently, immiscible substances like fuel oils are likely to be
highly retained (i.e., have a high residual saturation in the soil), which
will help limit the spread of a plume of fuel oil.  However, a high residual
saturation means that more product remains in the soil after much of the free
product plume has passed (CDM 1986).

     In addition to chemical and geological factors, other site-specific
factors affect the transport of released free product in the unsaturated 'zone.
Rainfall can increase the infiltration of water through the unsaturated zone,
where it will dissolve the water soluble components in the released product
and increase their spread through the subsurface environment.  Larger
quantities of released free product are more likely to spread farther and
faster than smaller releases.  Manmade features, such as pipelines, sewers,
and basements, also have the potential to facilitate movement of released
product because of the porous materials (e.g., gravel) commonly used as
backfill.
                                     C-14

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Inplications
                     ' • •    -'--','sS$?ijY .'     •.JDi.iO',-:' " .: •-' ;
     In general, heavier  petroleum products  with relatively high kinematic
viscosities,  such  as  fuel oil Nos.  5  and 6,  will not penetrate  soil as readily
as  the lighter petroleum  products,  such as gasoline,  kerosene,  and fuel oil
No. 2.  Exhibit C-6 shows that  gasoline is less viscous  than water, and the
fuel oils have kinematic  viscosities  greater than that of water.  As a result,
heating oils  tend  to  be less mobile in the subsurface environment than either
water or gasoline.

     As released petroleum products percolate through the soil,  they are
retained in pore spaces and as  surface coatings on soil  and rock particles
because of  adsorption.  The depth of  penetration of the  petroleum product from
the point of  release  into the geological matrix is directly related to its
retention within the  geological matrix and the  release volume.   Some
geological  matrices do not retain even highly viscous fuel  oil  very well.  For
example, a  release of fuel oil  No.6 from a 30,000-gallon fuel oil UST in
Hasting, Minnesota, penetrated  through fractured bedrock to a depth of at
least 80 feet (ICF 1988).

     Lighter  heating  oils (e.g.,  the  middle  distillates) will generally move
farther and faster than the heavier heating  oils (e.g.,  the residuals) because
of  their lower kinematic  viscosities.  For example,  fuel oil No. 6 will move
very slowly and is less likely  to reach the  saturated zone  than fuel oil No.
2.  Less permeable geological strata  have the additional effect of spreading
the plunto horizontally, increasing the area  of  subsurface contamination but
"decreasing  the amount of  contaminant  reaching the,ground water.  Gasoline,
because of  its higher mobility, is more likely  to reich  wells and will tend to
contaminate a larger  volume of  an aquifer than  will heavier petroleum
products.   Similarly,  fuel oil  No.  2   will tend to contaminate  a larger area
than fuel oil Nos. 4  or 6, all  other  things  being equal. However, the
concentration of fuel oil Nos.  4, 5,  or 6 in the contaminated area may be
greater, because the  fuel oils  will tend to  be  retained  by  the  subsurface
media and trapped  in  the  pore spaces  rather  than being dispersed and diluted.

C.2.2  Transport: of Free  Product on the Surface of the Water Table

General Discussion

     As released petroleum products travel downward through the vadose zone,
they pass through  zones of increasing water  saturation.   Eventually the
products reach the surface of the water table,  the boundary between the
saturated and unsaturated zones.   Because motor fuels and most  heating oils
are less dense than water and do not  mix readily with ground water, they tend
to  spread out on top  of the water table. When  free oil  initially reaches the
ground water, its  vertical movement .is stopped  where the pore spaces become
saturated with water.  As more  released product reaches  this region, a mound
begins to form on  the water table. If sufficient free product  is present,
then lateral  spreading begins.   Lateral migration ceases when the oil is at
its residual  saturation.   The flow results  in a characteristic  shape that
resembles a pancake  (CDM  1986).
                                     C-15

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     Some blends of fuel oil No. 6 are slightly more dense than water and do
not float on the surface of the water table.  The heavier fuel oils may slowly
sink to the bottom of the aquifer where they may remain.  Once at the bottom
of the aquifer they are very difficult to remove except by excavation.

     The shape of the floating contaminant plume depends largely on the
permeability of the soil, the percolation rate, ground-water velocity, and the
local water table configuration.  In general, the more permeable the soil, the
more the free product will spread laterally over the top of the ground water
table.  The steeper the hydraulic gradient (i.e., the tilt of the water
table), the narrower the plume will be.  The plume will also tend to be
elongated in the direction of the ground-water flow and the elongation will be
more pronounced where ground-water flow is fastest (CDM 1986).

     Most of the factors affecting contaminant flow through the unsaturated
zone will also affect the transport of the released products floating on the .
water table (Exhibit C-7).  The free products with higher viscosity will be
more attenuated and flow more slowly than less viscous products (e.g.,
gasoline).  Heavy rainfall will cause the water table to rise, and the free
product floating on the water table will be pushed upward toward the surface.
Some of the free product will be retained in the pore spaces of the
unsaturated zone after the water table returns to its previous levels.

     Petroleum products are composed of many constituents with different
physical and chemical properties that cause the* constituents to trayel at
different speeds in the subsurface environment; therefore, contaminant plumes
will separate as they flow on top of the ground water (Kerfo-/c and Sanford
1986).  The movement of the heavier fractions ar$ "retarded by adsorption and
retention in the capillary spaces, while the lighter fractions move faster and
farther forming the leading edge of the plume.  The lighter, more mobile
fractions will form the leading edge of the plume and reach exposure points
first, while the heavier, less mobile compounds will move slower and be less
likely to reach exposure points.                        ,

     Some of the less soluble constituents of the free product become trapped
in the pore spaces due to capillary forces.  Viscosity and insolubility of the
free product are largely responsible for the retention of free product in the
pore spaces.  This retention is likely to be only marginally reversible,
especially for heavier fuel oils, and greatly affects the kind of remediation
activities that can be used for cleanup.  Pump and treat options commonly used
for releases of gasoline will not be useful for remediation at many fuel oil
No. 6 releases; excavation will frequently be required to clean up
contaminated subsurface soil.                               ,

     The permeabi iity of the subsurface environment will also greatly
influence the horizontal movement of the contaminant plume.  Both manmade and
natural differences in the permeability can be significant.  Manmade features
like pipelines, wells, and basements can act as conduits for contaminant
transport through the subsurface.  Natural features like fractures in bedrock
also
                                     C-16

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                                 Exhibit C-7

                           MAJOR FACTORS AFFECTING
                          TRANSPORT OF FREE PRODUCT
                      ON THE SURFACE OF THE WATER TABLE
     FACTOR
     DEFINITION
      EFFECT
Permeability
Rainfall
Adsorption
Dens ity
Viscosity
Tendency of free product
to move through matrix.
Causes water table
to fluctuate, forcing
movement of free product
in unsaturated zone.

Tendency of free product
to cling to geological
matrix.
Weight of a substance
per unit volume.
Resistance of
fluid to relative
motion:
The more permeable the soil,
the more the free product
will spread over the top
of the aquifer.

Heavy rainfall will cause.
free product to rise
toward surface.
Differences in adsorption
cause free product to
sepa'rate into components;
lighter fractions move  .
farther than heavier '- ..
components.  '••''•'  ""    .

Generally,, -free product
is less, dense than water and
tends to float.

Increases from
gasoline, which is
not viscous, to fuel
oil No. 6, which is      .'--..'.-
highly viscous and       '••-.,.
tends not to flow.
Source:   ICF  Incorporated analysis.

                                     C-17

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facilitate subsurface transport.   Clay deposits will have lower permeability
and may cause irregularities  in the  shape  of the plume.

     Another important factor determining  the extent of the spread of
contamination is the volume of product released and the amount reaching the '
water table.  The degree that petroleum product spreads on the water table is
a direct function of the amount of product reaching the water table.

.Triplications

     Motor fuels tend to spread farther on top of the water than fuel oils   ;
because of their lower viscosities.  The size of the pancake formed by the
fuel oils will decrease as the fuel  oil number increases, all other factors
being equal (e.g., fuel oil No.  2  will tend to spread farther than No. 4,'
which in turn will tend to spread  farther  than No. 6).  An example of the
extent of product spreading comes  from a fuel oil No. 4 underground storage
tank system in Saint Paul, Minnesota,  which released 4,000 gallons of free
product into the ground. Soil borings  indicated a spill floating on the water
table between 60 and 100 feet in diameter  and between 13 to 20 feet deep (ICF
1988).  Transport of a relatively  viscous  fluid like fuel oil No. 4 over a
relatively large area demonstrates the potential for releases of free product
to reach exposure points, such as  wells or basements.

     Manmade features of the  subsurface environment are known to facilitate
the transport of released petroleum  products.  In one incident, a release of
fuel oil No. 6 from an exempt tank system  in Laurel, Maryland, reached a sewer
line, formed globules in the  water,  and traveled through a sewer to the
Patuxent River (ICF 1988).  Fuel oil N-~. 6 has also been reported to seep into
basements situated near leaking underg aund storage tank systems, such as in
Saint Paul, Minnesota, where  it leaked from a 50,000-gallon tank to a nearby
basement (ICF 1988).

     Released petroleum products that  are  retained in the pore spaces are a
continuing source of contamination (Kemblowski et al. 1987, Baradat et al.  .
1981).  Fluctuations in the water  table force the insoluble contamination
retained in the pore spaces to move, leading to additional exposures.  For
example, in Long Prairie, Minnesota, fluctuating ground water has led to the
discovery of additional contamination  in subsurface soil after remediation was
thought to have removed the contamination  at a site (ICF 1988) .

     The heavier fuel oils and nonvolatile residual products retained in the
pore spaces of the geological material are especially difficult to remove by
pumping.  Following a release in Falmouth,  Massachusetts, nonvolatile
residuals remained in the soil after fche source of contamination, a leaking
fuel oil No. 2 tank system, was removed and the ground water was being pumped
and treated (Kerfoot and Sanford 1986).  Even some fractions of kerosene,
which is relatively mobile, are likely to  remain in the ground after the more
mobile fractions have been removed by  pumping.  Baradat et al. (1981) found
light soluble aromatic components  in a shallow ground-water well (less than 12
meters deep) after a kerosene spill, but the heavier and less soluble
fractions did not appear in the water  and  were retained in a plume on top of
the aquifer.
                                     C-18

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C.2.3  Transport in the Saturated Zone
                 ' '   "*' ; '-*'''•' *'%t5i   ' '; , '*S*r?:'v:' '• '•-"
General Discussion

     The transport of product in the saturated zone depends primarily on two
factors:  density and solubility of the released.product (Exhibit C-8).
Because motor fuels and most heating oils are less dense than water, they tend
to be found only in the uppermost parts of the saturated zone.  The released
substance typically takes the form of an emulsion  t the interface between the
water-and oil phase.  The rate of movement depends on the local ground-water
gradients and the viscosity of the contaminants.  Adsorption will retard
movement of the more immiscible components.  Some heavier No. 6 fuel oils will
sink to the bottom of the aquifer because their density is greater than that .
of water.

     Some fraction of the lighter products (e.g., gasoline, kerosene, and fuel
oil No. 1) are soluble in water.  Water solubilities for the free products are
given in Exhibit C-6.   Residual fuels generally contain few soluble
constituents; soluble components of the lighter distillates will dissolve in
the ground water at a rate determined by the extent of contact between the
ground water, the free product, and the solubilities of the specific
constituents.  Rainwater seeping through the contaminant plume will also
dissolve soluble components.

     Once dissolved in the ground water, substances (primarily simple aromatic
compounds) will*move in the general direction of ground-water flow according
to the mass transport lams of advection and dispersion.  Advection is the
movement of a contaminant plume in the directionx*>f mean ground-water flow.
Dispersion describes how a contaminant spreads ou  and is diluted as it
occupies more of the saturated zone.  Dispersion can be caused by a variety of
factors, including molecular diffusion (the random movement of molecules of
the dissolved product through the ground water), but the principal cause is
generally variations in permeability of the geological material.  Dilution.
caused by dispersion is an important means of lowering contaminant
concentrations in the subsurface environment.

Implications

     Transport of the components of motor fuels and heating oils dissolved in
the water is a more significant problem for lighter products like gasoline and
kerosene than for heavier fuel oils, because the residuals have fewer soluble
components and these components tend to be present in much lower
concentrations.  In general, middle distillates have fewer water soluble
components, and the concentrations of these dissolved components will be lower
in the  ground water.  As with gasoline, the majority of the water soluble
fraction of middle distillates is composed of aromatic compounds (USEPA
1985e).  Residuals tend to have few constituents that are water soluble;
concentrations of residuals in the ground water are usually less than 20 ppm,
with polar and aromatic compounds comprising the majority of the soluble
components (USEPA 1985b).
                                     C-19

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                                 Exhibit C-8

                           MAJOR FACTORS AFFECTING
                         TRANSPORT OF HATER SOIUBLE
                      CONSTITUENTS IN THE SATURATED ZONE
FACTOR            DEFINITION                     EFFECT
Density           Weight of a substance         Generally, product  is  less
                  per unit volume.              dense  than water and will
                                                float.  Fuel oil No. 6 may
                                                be more dense  than  water and
                                                sink-

Solubility        Tendency of a substance       Monoaromatic fraction   ',;/-'
                  to mix with water.            (benzene  and alkyl     '•/."
                                                benzene), prevalent in
                                                gasoline, kerosene, and
                                                fuel oil  No  1, is  somewhat
                                                'soluble and  fill dissolve in
                                                and will  mix with ground
                    *'  .             •          •  water.- .  . "  '.••. •'" • • :-. '
Source:  ICF Incorporated analysis.
                                     C-20

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C.2.4  Transport of Vapors   "^:'        >ซ*                      ;

General Discussion                                                      .  *

     Lighter petroleum products,  such as gasoline,  kerosene,  and fuel oil Nos.
1 and 2, can enter the vapor phase in the subsurface environment.   Major
factors affecting the. transport of vapors are summarized in Exhibit C-9.
Volatility, the tendency to change into the vapor phase, is governed by vapor
pressure and Henry's Law constant.  Vapor pressure is relevant for assessing
volatility of free product and provides an indication of the tendency of     !
volatile compounds to pass into the gas phase from the contaminant plume.
Henry's Law constant is a partition coefficient measuring the distribution of
a substance between air and water and combines vapor pressure and solubility.
Henry's Law constant, therefore,  is a measure of a contaminant's tendency to :
volatilize from contaminated water.  Once in the gaseous phase, the volatile
components can move through the pore spaces of the soil.  The contaminant will
move by diffusion and advection,  "blown along" by subsurface air currents (CDM
1986).  Advection is controlled by fluctuations in barometric pressure,
pressure gradients across building foundations, density differences between
the air and vapor, and evaporation or chemical generation of vapor at a rate
much greater than can be removed by diffusion alone (CDM 1986).      .

     Molecules of gas may adhere to soil particles by adsorption,  similar to
absorption from the liquid phase.  After the plume passes and concentrations
in vapor are reduced, the adsorbed gas molecules may be released from the soil
particles and move with the vapor again.
                                                .st'"
     The size of the pore spaces in the unsaturated zone greatly inflt  mces
the migration of volatile compounds in the soil (Karimi et al. 1987).
Movement of soil gas may be blocked by imperious surfaces, such as geological
barriers and manmade structures.   Backfill materials used in construction are
especially permeable to soil gases, and vapors are known to move easily along
buried pipelines through the backfill (CDM 1986).  Leaking underground storage
tank systems have been detected by the smell of vapors in basements and by
routine monitoring of vapors that reach the ground surface above the tank
system.

Inplications

     Of the motor fuels and heating oils stored in exempt tank systems, the
light and middle distillates are much more likely to have constituents that
will evaporate in substantial amounts than the residual fuels.  Vapor
pressures of the free products are given in Exhibit C-6.  Gasoline h*-s a high
vapor pressure, meaning that it has a large number of constituents with
sufficient vapor pressures to evaporate in soils.  Although fuel oil No. 2
also has constituents that are likely to evaporate, the heavy distillates and
residuals do not have volatile components that are likely to be transported
with soil gases.  Little field data are available to estimate the potential
effects of vapor transport of petroleum products.  Alkyl benzene and some
normal alkanes have been reported in soil gas samples after a fuel oil No. 2
spill in Falmouth, Massachusetts (Kerfoot and Sanford 1986).  The Barnstable
                                     C-21

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                                 Exhibit C-9

                           MAJOR FACTORS AFFECTING
                             TRANSPORT OF VAPORS
FACTOR
DEFINITION
 EFFECT
Volatility
Pore Size
Adsorption
Tendency of solid or liquid
to enter vapor phase.
Size of pores in geological
matrix.
Tendency of vapor components
to cling to
matrix.
Lighter products (e.g.,
gasoline,  fuel oil No. 2)
will enter vapor phase in
subsurface environment.

Larger pore size facili-
tates transport of vapor
in subsurface.

Similar to liquids, vapor
may adsorb, increasing
the amount of product
retained in subsurface.
Source:  IGF Incorporated analysis.
                                     C-22

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 County (Massachusetts)  Health and Environmental Department is developing a
 leak detection program for exempt tank systems by monitoring the presence of
 vapors from heating oil in the soil (Stiefel and Heufelder 1987).

 C.2.5  Fate Processes

 General Discussion                   '

      Several mechanisms influence the retention of petroleum products in the
 subsurface environment and the hazard posed by a release (Exhibit C-10).
 Dispersion and dilution,  while not destroying the released constituents,  may.
 reduce their concentrations to undetectable levels.  Adsorption to geological
 materials and retention in the pore spaces may trap product in the subsurface
 indefinitely.  Constituents may be transferred to another medium, such as ,;  /
 volatilization to air or release to surface water, reducing their subsurface
 concentrations but possibly creating new environmental problems in other
 media.  Another mechanism, biodegradation, is a fate process that can reduce
 the concentration of contaminants in ground water over time.

      Dispersion and dilution can reduce concentrations of free products  in
 ground water.  These processes are not ultimate fate processes in that the
 products are still present, but concentrations may be reduced to such low
 levels that they cannot be detected.                                    .
'"        '                                                              '-' '.* •'.,
      Adsorption and retention in pore spaces increases the amount of time- that
 products will remain in the subsurface environment. .Some compounds may be
 essentially irreversibly bound or trapped in pore^spaces.  These compounds
 will b%' highly resistant to release and may remain trapped in the subsurface
 by these mechanisms indefinitely.  In other situations, adsorption simply
i separates the plume into fractions of differing mobilities.  Heavy metals in
 the products may also bind to particles by ionic exchange and become'
 immobilized.              •                              ...;-.

      Transferring contaminants to other media, such as air arid surface water,
 reduces the volume of contaminant in the ground water.  Volatilization can
 remove the contaminants from the subsurface environment by transferring it to
 the air.  Once in the air, constituents of release may be destroyed by
 sunlight (i.e., photodegrade) or may become dispersed and diluted in the air
 so that they are no longer present in measurable concentrations.  When
 released to surface water, product constituents are subject to a variety of
 processes that may reduce their concentration.  Contaminants may be diluted to
 unmeasurable concentrations, adsorb to particles and remain in the sediments,
 or photodegrade and biodegrade.                                           J

      Biodegradation is an important fate for some constituents of products
 released from exempt tank systems.  Several factors will affect the likelihood
 and rate of biodegradation.  These factors include temperature, pH, oxygen
 level, moisture content, nutrient levels, microbiota concentrations,
                                      C-23

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                                 Exhibit C-10

                             MAJOR FATE PROCESSES
PROCESS
     EFFECT
Dispersion and
Dilution
Adsorption and
Retention
Transfer to
other Media
Biodegradation
Reduce product concentra-
tions by spreading it
over larger area.

Irreversible binding will
retain product in subsurface
indefinitely.

Removes product from
subsurface to air or
surface water, transferring
problem to other media.
      /•
Some products will be
degraded by microorganisms
living in the subsurface
environment.
Source:  IGF .Incorporated analysis,
                                     C-24

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contaminant concentrations, and previous exposure of the microbiota to
contaminants (Mackay and Vogel 1985).  The variation and interactions of these
factors make it difficult to generalize about the biodegradation potential of
any particular product.  Brookman et al. (1985b) has noted the difficulty in
predicting biodegradation based on laboratory studies, and field studies are
rare.                                           .                 •

     The potential for products released from exempt tank systems to
biodegrade depends strongly on the specific contaminants involved.  In
general, researchers have found straight chain paraffinic hydrocarbons aie the
most susceptible to degradation, and aromatics are the least degradable.
Examination of the susceptibility of hydrocarbons in weathered fuel oil Nos. 2
and 6 to microbial degradation revealed less degradation of No. 6 (Atlas
1981).  Even identical compounds were less degraded in fuel oil No. 6 than No.
2, presumably because of the interaction with other constituents.  Some
degradation was reported when fuel oil No. 6 was applied to topsoil (Kincannon
1974).  However, the microbial populations at the top surface of the soil are
much different than those in the subsurface, partly because the levels of
nutrients and oxygen are lower in the subsurface environment, thereby reducing
the rate of biodegradation.  Consequently, studies such as this indicate a
maximum potential biodegradation, rather than an expected level of
biodegradation in the subsurface.

     In another surface soil study, only about 50 percent of the fuel oil No.
6 was degraded after a year under ideal degradation conditions (Raymond et al.
1976) .  This study indicated that all classes of hydrocarbons would degrade,
but that nonpolar hydrocarbons degrade much slower than other hydrocarbons.
Studies on marine organisms, which are not a direct indication of subsurface
microbial activities but do give a general idea of inherent biodegradability
of the petroleum products, indicate that straight-chained paraffins and
aromatic compounds are the first to degrade and that, many of the compounds
most resistant to degradation were branched and cyclic aliphatic .hydrocarbons
(Pierce et al. 1975).                                     .

     Researchers, such as McKee (1972), Davis (1972), and McCarty et al.
(1984), have found that biodegradation is most likely to occur where oxygen is
plentiful (i.e., closer to the surface or nearer aerated ground water).
Abundant oxygen is especially important in limiting the spread of simple
aromatic compounds that are somewhat soluble, like benzene, toluene, and
xylene, as well as those that are degraded by microorganisms requiring oxygen
to survive (i.e., aerobic microorganisms).  Biodegradation by aerobic
microorganisms was thought to have accounted for reductions in the
concentrations of aromatic compounds after source removal, but before source
remediation in a. leak of fuel oil No. 2 (Kerfoot and Sanford 1986).

Implications

     Available information suggests that gasoline will be the most degradable
of the petroleum products and fuel oil No. 6 will offer the greatest
resistance to degradation.  Biodegradation can limit the spread of the soluble
aromatic fraction of gasoline, which is associated with the greatest health
risk. Those heavier fuel oils will not be readily biodegradable, however,
                                     C-25

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because the biodegradation of those fuel oils is  inhibited by  the large size
and insolubility of  their  constituent molecules.   Even kerosene  is expected to
remain largely  in  the  ground (Baradat et al.  1981).  Thus, untreated
contamination from heating oils will remain in the subsurface  environment
longer than contamination  from gasoline.

     Transfer of released  petroleum products  from the  subsurface to surface
water  has been  reported many times.   In one situation, 500 gallons of fuel oil
released from an exempt tank system accumulated on the surface of a small lake
near ?ark Rapids,  Minnesota (IGF  1988).   In another  situation, 200 to 300
gallons of heating oil leaking from an underground storage tank  system in
Grookston, Minnesota,  entered a sanitary sewer and contaminated  the Red Lake'
River  (ICF 1988).  In  these cases,  not only was soil and ground  water cleanup
necessary, but  actions had to be  taken to prevent the  spread of  contamination
on surface water as  well.
 C.3 HAZARD POTENTIAL

     Previous parts  of this  appendix have examined (1)  the composition of'
 petroleum products and the adverse health effects  that  may be associated with
 exposures to the  fuels and their  constituents  and  (2) how the petroleum
 products  released from underground storage tanks may be transported through
 the environment and  contaminate soil and ground water.   This last section
 discusses the possible ways  in which humans may come into contact with the
 contaminated media,  and *;he  hazards  that may be associated with  those
 exposures.
                                                /           .     • • '   ••:-.
     Humans may be exposed to  petroleum products released from underground
.storage tank systems through contact with contaminated  air, soil, surface
 water, or ground  water.. The most likely means of  human, exposure to the water-
 soluble components of petroleum products from  underground tank systems is
 contact with contaminated ground  water.   Such  exposures\can occur through  :
 consumption of contaminated  water, absorption  through the skin during bathing
 or washing, and inhalation of  volatilized components during showering.
 Exposure  can also occur when motor fuels and fuel  oils  seep into basements of
 residences  and commercial establishments.   Contact with fuels pooled in
 basements may result in absorption of  the substance through the  skin.
 Significant exposures can also result  when accumulated  vapors from seepages
 are inhaled; however, this exposure  route is important  only for  the more
 volatile  fuels, such as gasoline  and kerosene,  and,  to  a lesser  extent, diesel
 fuel and  fuel, oil No. 2. Seepages may also result in a buildup  of explosive .
 vapors and  put persons and property  at risk of explosion or fire.  Human  '
 exposure  to contaminated surface  water is less of  a threat than  other types of
 exposure, because the potential contamination  is more likely to  be readily
 visible and avoided.

     Humans can also be exposed through contact with contaminated soil.  Soil
 can become  contaminated when fluctuations in the water  table 'cause released
 petroleum products to rise to  the surface.   Releases have been detected when
 dead patches appear  in grass or other  surface  vegetation.  Contaminated soil
                                     C-26

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may also be brought to the surface during excavation of an area during cleanup
of a release.         .•    '  r''f""'3  ''   ' :'-:?*> '•-:•'•,ป' ! -•

     High concentrations of contaminants in ground water and ambient air are
likely to be detected by taste or smell, and in many cases, corrective action
may be taken before long-term health effects are.observed.  Because low level
contamination is likely to go undetected, however, extended exposures to low
levels of contamination may pose a long-term threat to human health.

     Each of the main categories of heating oils (middle distillates and
residual fuels) poses different health risks based on their toxicities
(Exhibit C-2) and their ability to be transported through the environment to
places where human may encounter them.  These health risks are summarized     .
below.

C.3.1     Gasoline

     Gasoline moves relatively easily through the environment, making
contamination of ground water by gasoline released from underground storage
tank systems likely.  Long-term inhalation of gasoline vapors has been
associated with cancer,  which may be caused in part by benzene.  Risks from
releases from exempt motor fuel tank systems are less than risks from releases
from regulated motor fuel USTs, however, because the capacity of these exempt
tank systems and the potential quantity released is smaller.

C.3.2     Middle Distillate Fuels

     The middle distillate fuels move fairly easily through the environment
and releases of these fuels can be expected to contaminate ground water.
Diesel fuel and fuel oil No. 2 have been shown to be weak to moderate
carcinogens when painted on the skin of laboratory animals, and several other
components of the middle distillates are known to have adverse health effects.
The chemicals of greatest concern include toluene, xylene, and PAHs.  Toluene
and xylene are present at much lower concentrations in middle, distillates than
those found in gasoline, but may still be of concern.  A rioncarcinogenic PAH,
naphthalene, is present in the middle distillates in significant
concentrations and may pose a health risk when dissolved in ground water, even
in low concentrations. Two PAHs, benzo(a)pyrene and benzo(a)anthracene, have
been detected at very low concentrations.  These compounds are generally less
water soluble than toluene and xylene, but they are probable human
carcinogens.  The constituents of middle distillates, however, have not been
well studied and it is likely that the compounds listed above are not the only
toxic constituents of these fuels; consequently, the toxicities of these
compounds may not be representative of the true toxicity of the middle
distillates.

C.3.3     Residual Fuels

     The residual fuels, fuel oil No. 6 in particular, contain higher
concentrations of PAHs than middle distillates.  Residual fuels may also
contain blending agents that have been shown to be potent carcinogens in
animals.  The residual fuels are very viscous, however, and it is unlikely
                                     C-27

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that a significant quantity of the fuel would reach drinking water wells.  In
addition, the low water solubilities of most constituents of residual fuels
make it unlikely that an aquifer would become extensively contaminated.
However, there have been reports of fuel oil No. 6 reaching water tables and
contaminating ground water.  The extent of the contamination is unknown.
Therefore, while the potential for ground water contamination by residual
fuels is not as great as for the middle distillates, the potential for such
releases exists.  These fuels may contain potent animal carcinogens and,
.therfore, these releases may pose a threat to human health.

     In conclusion, releases of middle distillate fuels, and to a lesser
extent, residual fuels leaking from underground storage tank systems can
contaminate ground water.  In addition, leaks of the lighter middle
distillates may seep into basements and release potentially explosive vapors.
The health risks associated with releases of the middle distillate fuel oils
may be significant; those associated with releases of the residual fuel oils
are believed to be less, but still of concern because of the presence of PAHs
and a variety of blending agents shown to be carcinogenic in animals.
                                     C-28

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Arizona:

California:

Connecticut::


Delaware:

Florida:

Hawaii:

Illinois:


:Iowa:

Kansas:

Kentx-cky:

Louisiana:


Maine:

Maryland:


Massachusetts:

Michigan:

Minnesota:

Montana:

Nebraska:

New Hampshire:

New Jersey:

New Mexico:
            "•">  APPENDIX D

SOURCES OF STATE AND LOCAL STATUTES AND CODES


   Arizona Revised Statutes, sec. 36-3301.11.

   California Health and Safety Code, sec. 25281(r).

   Regulations of Connecticut State Agencies, sec. 22a-449(d)-
   W-                                              •••:";:•:*;'..
   Delaware Code, Chapter 74, Title 7, sec. 7406.            .'

   Florida Statutes, Chapter 376, sec. 376.301(4).

   Hawaii Revised Statutes, sec. 342-61.

   Illinois Administrative Code, Subtitle G, Chapter I,
   Subchapter d, Part 731.101(d).                      ,  ''/'•'.'

   Iowa Administrative Code, Chapter 135, sec. 455B.471,6,;
                                                       ' *'••••"
   Kansas Administrative Regulation, Article 28-44.

   Kentucky Revised Statutes, sec;' 224.810(1).

   Code of Regulations, Title 32, Part XI, Chapter 3.;lsec.
   3p5.                         '   '   '-._.-• V,-  - •"••'• "VV

   State of Maine, 38 MRSA 562(13), (14).:   .   .-'..

   Code of Maryland Regulations, Title 8; Subtitle 5, Chapter
   4, sec. 09.

   Code of Massachusetts, Volume 15, Title 527, sec. 9.00.

   Michigan Compiled Laws, Chapter 23, sec. 13.29(71).

   Minnesota Code, sec.. 116.47.

   Montana Code, sec. 75-10-403(17).                       :

   Nebraska Revised Statutes, sec. 81-15, 119(7).

   New Hampshire Code of Administrative Rules, Part Ws 411.

   New Jersey Code, sec. 58:10A-22.p.

   New Mexico Code, sec. 74-4-3.
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New York:

North Carolina:


North Dakota:

Rhode Island:


South Carolina:

South Dakota:

Texas:

Utah:

Vermont:

Virginia:

Wyoming:
New York Code of Rules and Regulations,  Title 6.

North Carolina General Statute NCGS 143-6-282(2)(h) and
NCGS 143 215.3(a)(15).

North Dakota Code,  sec. 23-20.3-02 support 17.

Rhode Island Regulations for Underground Storage  Facilities
for Petroleum Products and Hazardous Materials.

South Carolina Code of Regulations, R.61-92.0.

South Dakota Codified Laws, sec.  34A-2-98(s).

Texas Water Code, sec. 26.344.

Utah Health Code, sec. 26-14-2(1.3).

Vermont Code T.10 sec. 1922 (10).

Virginia Code, sec. 62.1.44.34:8.

Wyoming Environmental Quality Act, sec.  35-11-101 et seq.
Barnstable County Health and Environment Department, "Underground Fuel Storage
In Bamstable County, Massachusetts," First Interim Report, Revised Kay 4,
1987.

Cape Cod Planning and Economic Commission.  "Model Health Regulations to
Prevent Leaking of Underground Fuel and Chemical Storage Systems," Last
Amended February, 1982.

City of Austin, Texas.  Austin City Code, 1981, Chapter 9-10, Article VI -
"Hazardous Materials Storage and Registration," Effective June 18, 1985.

County of Suffolk, New York.  Suffolk County Sanitary Code, Article 12 -
"Toxic and Handling Controls," Adopted January 1, 1980.

Metropolitan Dade County, Florida.  The Code of Metropolitan Dade County,
Chapter 24, Section 12.2, "Regulations for Underground Storage Facilities,"
Effective November 25, 1983.
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                                  APPENDIX E

                             DEFINITIONS OF TERMS
    The following terms are defined in order to establish which tank systems
are regulated under Subtitle I of RCRA and which heating oil and motor fuel
tank systems are excluded under the definition of an underground storage tank
(UST) in Subtitle I and, therefore, exempt from regulation.

    •    Underground Storage Tank (UST):   The term underground storage tank
         means any one or combination of tanks (including underground pipes
         connected thereto) that is used to contain an accumulation of
         regulated substances, and the volume of which (including the volume
         of the underground pipes connected thereto) is 10 percent or more
         beneath the surface of the ground.  This term does not include any
         farm or residential tank of 1,100 gallons or less capacity used for
         storing motor fuel for noncommercial purposes or tanks used for
         storing heating oil for consumptive use on the premises where stored.

    •    Regulated Substance:   The term regulated substance means any
         substance defined in section 101(14) of the Comprehensive
         Environmental Response, Compensation,  and Liability Act of 1980 (but
         not including any substance regulated as a hazardous waste under
         subtitle C),  and petroleum, including crude oil or any fraction
         thereof which is liquid at standard conditions of temperature and
         pressure.

    •    Tank:   Tank is a stationary device designed to contain an
         accumulation of regulated substances and constructed of non-earthen
         materials (e.g., concrete,  steel,  plastic) that provide structural
         support.

    •    Tank System:   Tank system means  an underground tank,  connected
         piping, underground ancillary equipment,  and containment system,  if
         any.

    •    Farm tank:  A fan* tank is a tank located on a tract of land devoted
         to the production of crops or raising  of animals,  including fish,  and
         associated residences and improvements.   To be exempt from UST
         jurisdiction,  a farm tank must be  located on the farm property.
         "Farm" includes fish hatcheries,  rangeland, and nurseries with
         growing operations.

         "Farm" does not include laboratories where animals are raised,  land
         used to grow  timber,  and pesticide aviation operations.   Moreover,
         this  definition does  not include  retail  stores or  garden centers
         where the  product of nursery farms is  marketed,  but not produced.

    •    Residential Tank:   Residential tank is a tank located on property
         used primarily for dwelling purposes.
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Motor Fuel:  Motor fuel is defined as a category of petroleum that is
comprised of motor gasolines, aviation gasolines, No. 1 and No. 2
diesel fuels, and all grades of gasohol, and that is typically used
to power a motor engine.

Heating Oil:  Heating oil is defined as a category of petroleum that
is comprised of No. 1, No. 2, No. 4-light, No. 4-heavy, No. 5-light,
No. 5-heavy, and No. 6 technical grades of fuel oil and is typically
used in the operation of heating equipment, boilers, or furnaces.

Noncommercial purposes:  NoncoHwrcial purposes with respect to motor
fuel means not for resale.

Consumptive Use:  Consumptive use means burned on the premises.  This
exclusion applies to tanks at residential, commercial, and industrial
facilities storing heating oil that is used at the same site.  The
heating oil exclusion does not apply to the storage of heating oil
for resale, marketing, or distribution.

On the premises where stored:  On the premises Where stored means
tanks located on the same property where the stored heating oil is
used.  Tanks are excluded as long as the oil is stored anywhere on
the same property.  "On the premises" is not limited to the building
where the heating oil is  stored.  Thus, centralized facilities using
heating oil in boilers that serve more than one building on the same
property would be excluded.
                                                                       0
                            E-2

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                          REFERENCES FOR APPENDICES
American Conference of Governmental Industrial Hygienists (ACGIH).  1980.
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American Petroleum Institute  (API).  1983.  Memorandum dated June 24, 1983,
from C. DiBona, President of  API, to members.  FYI submission from API to Mr.
William Ruckleshaus, Administrator, U.S. EPA.  FYI-AX-0783-Q148, Supp.
Sequence H, July 15, 1983.  (As cited in USEPA 1985a).

American Petroleum Institute  (API).  1985.  Unpublished information on the
production, use, exposure, and toxicity of petroleum residual fuels.
Submitted by S.M. Swanson, American Petroleum Institute.  February 28.  (As.
cited in USEPA 1985b).
American Society of Testing and Materials (ASTM).
Standards, Section 5, Vol. 05.01.  Philadelphia.
            1986.  Annual Book of ASTM
Atlas, R.M.  1981.  Microbial degradation of petroleum hydrocarbons: an
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Baradat, Y., J.S. Lemlin, P. Sibra and H. Somerville.  1981.  A Review of the
Investigation of a Kerosene Spill at Strasbourg - Entzheim Airport, France.
CONCAWE, The Hague, Netherlands.

Barrientos, A., M. Ortuno, J. Morales, F. Tello and J. Rodicio.  1977.   Acute
renal failure after use of diesel fuel as a shampoo.  Archives of Internal
Medicine 137:1217.  (As cited in Gosselin et al. 1984).
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and related compounds for mouse skin.
The tumor-promoting action of phenol
Cancer Research 19:413-424.
Brookman, G.T., M. Flanagan and J.O. Kebe.  1985a.  Laboratory Study on
Solubilities of Petroleum Hydrocarbons in Groundwater.  Prepared for
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Environmental Consultants, East Hartford, CT.

Brookman, G.T., M. Flanagan and J.O. Kebe.  1985b.  Literature Survey:
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Components.  Prepared for Environmental Affairs Department,  American Petroleum
Institute.  TRC Environmental Consultants, East Hartford, CT.
California State Water Resources Control Board.
Base.  December 1986.
          1986.   UST Notification Data
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Gamp, Dresser, and McKee, Inc. (CDM).  1986.  Interim Report: Fate and
Transport of Substances Leaking from Underground Storage Tanks.  Volume 1 -
Technical Report.  Prepared for Office of Underground Storage Tanks, EPA,
under contract No. 68-01-6939.  Camp, Dresser, and McKee, Boston, HA.

Crisp, A., A. Bhalla and B. Hoffbrand.  1979.  Acute tubular necrosis after
exposure to diesel oil.  British Medical Journal 2:177-178.  (As cited in
Gosselin et al. 1984).

Davis, J.B., V.E. Farmer, R.E. Kreider, A.E. Straub and R.M. Reese.  1972.
The Migration of Petroleum Products in Soil and Ground Water Principles and
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Petroleum Institute, Washington, D.C.

GCA Corporation.  1983.  Sample of virgin fuel oil from suburban Philadelphia.
October 28, 1983.  (As cited in CDM 1986).

Goodger, E.  1975.  Hydrocarbon fuels.  John Wiley and Sons, New York, NY.
(As cited in CDM 1986).

ICF Incorporated.  1988.  Summary Notes of December 2, 1987 Meeting with State
and Local Officials Concerning Federally Exempt Tank Systems.  Prepared for
Office of Underground  Storage Tanks, EPA.  January 1988.

International Agency For Research on Cancer (IARC).  1983.  IARC Monographs on
the Evaluation of the  Carcinogenic Risk of Chemicals to Humans.  Vol. 32:
Polynuclear Aromatic Compounds; Fart 1, Chemical, environmental and
experimental data.  World Health Organization, Lyon, France.

International Agency For Research on Cancer (IARC).  1984.  IARC Monographs on
the Evaluation of the  Carcinogenic Risk of Chemicals to Humans.  Vol. 33:
Polynuclear Aromatic Compounds; Part 2, Carbon blacks, mineral oils and some
nitroarenes.  World Health Organization,  Lyon, France.

Karimi, A.A., W.J. Farmer and M.M. Cliath. 1987.   Vapor-phase diffusion in
oil.  Journal of Environmental Quality 16:38-43.

Kemblowski, M.W., J.P. Salanitro, G.M. Dealey and C.C. Stanley.  1987.  Fate
and transport of residual hydrocarbon in groundwater - A case study -
Abstract.  Presented at Petroleum Hydrocarbons and Organic Chemicals in Ground
Water: Prevention, Detection, and Restoration.  Houston, TX.  November 17-19,
1987.

Kerfoot, W.B. and W. Sanford. 1986.  Four dimensional perspective of an
underground fuel oil tank leakage.  Pages 382-401 in Proceedings of Petroleum
Hydrocarbons and Organic Chemicals in Ground Water: Prevention, Detection and
Restoration.  Houston, TX.  November 12-14, 1986.  National Water Well
Association, Dublin, OH.

Kincannon, C.B.  1974.  Oily waste disposal by soil cultivation process.  EPA
Report R2-72-110.  U.S. Environmental Protection Agency, Washington, D.C.
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Kolpack, R., B. Mechalas, T. Meyers, N. Plutahak, and E. Eaton.  1973.  Fate
of oil in a water environment.  Phase I Division of Environmental Affairs.,
American Petroleum Institute.  (As cited in USEPA 1985b).
Litton Bionetics, Inc.  1977.  Hutagenicity evaluation of kerosene.
report prepared for American Petroleum Institute.
                                   Final
Lu, B. and J. Polak. 1973.  A study of the solubility of oil in water.
Prepared for Environmental Emergency Branch, Department of the Environment,
Canada.  Report EPS-4-EC-76-1.

Mackay, D.M. and T.H. Vogel.  1985.  Ground water contamination by organic
chemicals: uncertainties in assessing impact.  Pages 50-59 in B. Hitchon and
M.R, Trude11, editors.  Proceedings of the Second Canadian/American Conference
on Hydrogeology.   National Water Well Association, Dublin, OH.
Maine Department of Environmental Protection.
Base.  December 1986.
             1986.  UST Notification Data
McCarty, P.L., B.E. Rittman and E.J. Bouiver.  1984.  Microbiological
processes affecting chemical transformation in groundwater.   Pages 90-115 in
G. Bitton and C.P. Gerba, editors.  Groundwater Pollution Microbiology.   John
Wiley, New York, NY.

McKee, J.E., F.B. Laverty and R.M. Hectel.  1972.  Gasoline in groundwater.
Journal Water Pollution Control Federation 44:293-302.

Montana Department of Health and Environmental Science.  1987.  UST
Notification Data Base.  March 1987.

National Institute for Occupational Safety and Health (NIOSH).  1977.
Occupational exposure to refined petroleum solvents.  U.S. Department of
Health Education and Welfare, Cincinnati, OH.

National Petroleum Council.  1984.  Petroleum Inventories and Storage
Capacity:  A Report of the National Petroleum Council.  June 1984.
Neff, J. and Anderson, J.  1981.
specific petroleum hydrocarbons.
cited in USEPA 1985b).
Response of marine animals to petroleum and
London:  Applies Science Publishers.   (As
Oil Heat Task Force.  1987.  Comments to the Office of Underground Storage
Tanks, EPA, on its Contractor Draft "Study of the U.S. Population of USTs
Exempted under Subtitle I of RCRA."  September 30, 1987.

Pancirov, R. and R. Brown.  1975.  Analytical Methods for Polynuclear Aromatic
Hydrocarbons in Crude Oils, Heating Oils and Marine Tissues.   Conference on
Prevention and Control of Oil Pollution, San Franscisco.

Petroleum Marketers Association of America (PMAA).  1987.  Comments on Draft
Study of Heating Fuel Tank and Motor Fuel Tank Exempt from EPA Regulations.
September 23, 1987.
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Pierce", R.H. , A.M. Cundell and R.W. Traxler.  1975.  Persistence and
biodegradation of spilled residual fuel oil on an estuarine beach.  Applied
Microbiology 29:646-652.

Pim, J.  1987.  Interim Report II, Tank Corrosion Study, Federally Exempt
Tanks.  Prepared for Office of Underground Storage Tanks, EPA.  Prepared by
Suffolk County Department of Health Services, NY.  November 1987.

Pim, J.  1988.  Interim Report III, Tank Corrosion Study Federally Exempt
Tanks.  Prepared for Office of Underground Storage Tanks, EPA.  Prepared by
Suffolk County Department of Health Services, NY.  February 1988.

Raymond, R.L., J.O. Hudson and V.W. Jamison.  1976.  Oil degradation in soil.
Applied and Environmental Microbiology 31:522-535.

Rose, J. and J. Cooper.  1977.  Technical data on fuel.  John Wiley and Sons,
New York, NY.  (As cited in USEPA 1985c).

Speight, J.  1980.  The chemistry and technology of petroleum.  Marcel Dekker,
Inc., New York, NY.

Stiefel, C. and G. Heufelder.  1987.  Underground Fuel Storage in Barnstable
County, Massachusetts.  Prepared for EPA Region 1, Boston, MA, under Grant
#X813724010.  October 20, 1987.  Barnstable County Health and Environmental
Department, Barnstable, MA.

Thomas, B. 1984. Coefficients from aqueous solutions from four fossil fuels
(Masters Thesis).  Pacific Northwest Lab, Richland, WA.

Tomkins, B. and W. Griest.  1987.  Liquid chromatographic determination of
Benzo(a)pyrene at part per billion concentrations in highly refined coal and
petroleum derived fuels.  Journal of Chromatography 386:103-1120.

U.S. Air Force (USAF).  1986.  Personal communication with Wanda King and Ken
Makara by SCS Engineers of November 20, 1986.

U.S. Army (USA).  1986.  Personal communication with Bill Shaw and Jim Gruber
by SCS Engineers of November 20, 1986.

U.S. Department of Agriculture.  Unpublished data.  1985 Farm Costs and
Returns Survey.  National Agricultural Statistics Services, Washington, DC.

U.S. Department of Commerce.  1985.  1982 Census of Manufacturers.  Subject
Series, Fuels and Electric Energy Consumed.  Fart 2, States and Standard
Metropolitan Statistical Areas by Major Industrial Group.  Bureau of the
Census, Washington, DC.

U.S. Department of Commerce.  1987.  Current Population Reports,  Population
Estimates and Projections, State Population and Household Estimates to 1985,
with Age and Components of Change.  Series P-25, no. 998.  Bureau of the
Census, Washington, DC.
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U.S. Department of Commerce (Bureau of the Census) and U.S. Department of
Housing and Urban Development.  1985.  Annual Housing Survey: 1983, U.S. and
Regions, Part F, Energy-Related Housing Characteristics (Current Housing
Report Series H-150-83).  September 1985.  Washington, DC.

U.S. Department of Energy.  1982.  Residential Energy Consumption Survey,
1980-1981, Consumption and Expenditures, (Part 1, National Data).  September
1982.  Energy Information Administration, Washington, DC.

U.S. Department of Energy.  1985.  Non-residential Buildings Energy
Consumption Survey: Characteristics of Commercial Buildings 1983.  July 1985.
Energy Information Administration, Washington DC.

U.S. Environmental Protection Agency (USEPA).  1974,  Waste Automatic
Lubricating Oil Reuse As a Fuel.  September 1974.  EPA 600 15-74-032.  Office
of Research and Development, Washington, DC.

U.S. Environmental Protection Agency (USEPA).  1980.  Ambient Water Quality
Criteria for Phenol.  October 1980.  EPA 440/5-80-066.  Office of Water
Regulations and Standards, Criteria and Standards Division, Washington, DC.

U.S. Environmental Protection Agency (USEPA).  1982.  An Exposure and Risk
Assessment for Benzo(a)pyrene and the Polycyclic Aromatic Hydrocarbons:
Volume II-Naphthalene (Final Draft Report).  WH-553.  Office of Water
Regulations and Standards, Washington, DC.

U.S. Environmental Protection Agency (USEPA).  1984a.  Health Effects
Assessment for Toluene.  Environmental Criteria and Assessment Office,
Cincinnati, OH.

U.S. Environmental Protection Agency (USEPA).  1984b.  Health Effects
Assessment for Cresols (Final Draft).  ECAO-CIN-H050.  September 1984.
Environmental Criteria and Assessment Office,  Cincinnati, OH.

U.S. Environmental Protection Agency (USEPA).  1985a.  Information Review of
Unleaded gasoline (Draft Report).  Prepared under EPA Contract No.  68-01-6650.
IR-469.  February 8, 1985.  TSCA Interagency Testing Committee,  Washington,
DC.

U.S. Environmental Protection Agency (USEPA).  1985b.  Information Review of
Residual Fuel Oils (Draft Report).  Prepared under EPA Contract No.  68-01-
6650.  IR-471.  April 19, 1985.  TSCA Interagency Testing Committee,
Washington, DC.

U.S. Environmental Protection Agency (USEPA).  1985c.  Health Effects
Assessment for Ethyl Benzene.   Environmental Criteria and Assessment Office,
Cincinnati, OH.

U.S. Environmental Protection Agency (USEPA).  1985d.  Health and
Environmental Effects Profile for Phenol.  Errata, 1986.   Prepared for the
Office of Solid Waste and Emergency Response, EPA.  Environmental Criteria and
Assessment Office, Cincinnati, OH.
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 U.S.  Environmental Protection Agency (USEPA).   1985e.   Information Review of
 Petroleum Middle Distillate Fuels  (Draft  Report).   Prepared under EPA Contract
 No. 68-01-6650.   IR-470.   March 15,  1985.   TSCA Interagency Testing Committee,
 Washington,  DC.

 U.S.  Environmental Protection Agency (USEPA).   1985f.   Health and
 Environmental Effects  Profile for  Phenol.   Errata,  1986.  Prepared for the
.Office  of Solid  Waste  and Emergency  Response,  EPA.  Environmental Criteria and
 Assessment Office,  Cincinnati,  OH.

 U.S.  Environmental Protection Agency (USEPA).   1986a.   Underground Motor Fuel
 Storage Tanks: A National Survey.  May  1986.   Office of Pesticides and Toxic
 Substances,  Washington,  DC.

 U.S.  Environmental Protection Agency (USEPA).   1986b.   Superfund Public Health
 Evaluation Manual.   Office of Emergency and Remedial Response, Washington, DC.

 U.S.  Environmental Protection Agency (USEPA).   1986c.   Health and
 Environmental Effects  Profile for  Xylenes  (o-,  m-,  p-).  Prepared for the
 Office  of Solid  Waste  and Emergency  Response,  Office of Air Quality Planning
 and Standards, and Office of Air and Radiation,  EPA.  Prepared by
 Environmental Criteria and Assessment Office,  Cincinnati, OH and Research
 Triangle Park, NC.

 U.S.  Marine  Corps (USMC).   1986.   Personal  communication with Laura Huber and
 Captain Hilliker by SCS  Engineers  of November  21, 1986.

 U.S.  Navy (USN).   1986.   Personal  communication with Elizabeth Ford and Brian
 Collins by SCS Engineers  of December 10,  1986.

 Weiss,  G.  1981.   Hazardous Chemical  Databook.   Noyes Data Corporation, Park
 Ridge,  N.J.

 Wisconsin Department of Industry,  Labor,  and Human  Relations.  1987.  UST
 Notification Data Base.   February  6,  1987.
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