ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 280

[FRL-3385-3]

Underground Storage Tanks;

Technical Requirements

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

 

SUMMARY: The Environmental Protection Agency (EPA) today finalizes 

regulations for underground storage tanks containing petroleum or 

substances defined as hazardous under the Comprehensive Environmental 

Response, Compensation, and Liability Act of 1980 (CERCLA), except any 

substance regulated as a hazardous waste under Subtitle C of the 

Resource Conservation and Recovery Act (RCRA). These regulations were 

first proposed on April 17, 1987 (52 FR 12662) and a subsequent 

Supplemental Notice was published on December 23, 1987 (52 FR 48638).

Under Section 9003 of RCRA, EPA must establish requirements for 

leak detection, leak prevention, financial responsibility, and 

corrective action for all underground storage tanks containing regulated 

substances as necessary to protect human health and the environment. 

Today's final rule sets forth requirements satisfying the mandates of 

section 9003, except that final requirements concerning financial 

responsibility will be addressed later by EPA in another FEDERAL 

REGISTER notice.

EFFECTIVE DATE: [Insert date 90 days after publication in the FEDERAL 

REGISTER], except § 280.22(g) which is effective [insert date 30 days 

after publication].

ADDRESSES: The docket for this rulemaking (Docket No. UST 2-1) is 

located at the U.S. Environmental Protection Agency, 401 M Street, S.W., 

Washington, DC 20460. The docket is open from 9:30 a.m. to 3:30 p.m., 

Monday through Friday, except for federal holidays. You may make an 

appointment to review docket materials by calling (202) 475-9720. You 

may copy a maximum of 50 pages of material from any one regulatory 

docket at no cost. Additional copies cost $0.20 per page.

FOR FURTHER INFORMATION CONTACT: The RCRA/Superfund Hotline at (800) 

424-9346 (toll free) or 382-3000 (in Washington, DC).

SUPPLEMENTARY INFORMATION: The contents of today's preamble are listed 

in the following outline:
I. Authority

II. Background

A. Subtitle I of RCRA

B. Operating Principles

C. Summary of April 17 Proposed Rule

D. Public Comment on the Proposal

E. Summary of the Supplemental Notice and the Notice of 

Availability of New Information

F. Influences on the Final Rule

1. Scope of the Problem

2. New Cause-of-Release Information

3. Industry Codes and Practices

4. Industry Trends 

5. UST System Technology Development

6. Leaking USTs Present A Unique Regulatory Challenge

7.Emerging State and Local UST Programs and EPA's Approach to 

Regulation

G. Conclusions Since Proposal

III. Today's Final Rule

A. Summary of Today's Final Rule

B. Major Points of Departure from April 17 Proposal

1. More Frequent Tank Tightness Testing of Existing

Unprotected Tanks During the 10-Year Upgrade Period

2.Less Frequent Monitoring of New and Upgraded Tanks Until 

Age 10

3. Gradual Phase-in of Release Detection Based on Age

4. More Stringent Requirements for Pressurized Piping

C. Alternative Approaches Considered

1. New UST Systems Containing Petroleum

2. Existing UST Systems Containing Petroleum

3. Hazardous Substance UST Systems

4. Corrective Action

IV. Analysis of Today's Rule

A. Program Scope

1. Applicability

2. Regulatory Exclusions

3. Deferral of Regulations

4. Definitions

B. UST Systems: Design, Construction, Installation, and

Notification
1. Design and Construction Requirements (§ 280.20)

2. Installation (§§ 280.20(d) and (e))

3. Upgrading of Existing Systems (§ 280.21)

4. Notification (§ 280.22)

C. General Operating Requirements

1. Spill and Overfill Control (§ 280.30)

2.Operation and Maintenance of Corrosion Protection 

(§ 280.31)

3. Inspection and Maintenance of the Tank System (§ 280.31)

4. Compatibility ( § 280.32)

5. Repairs (§ 280.33)

6. Reporting and Recordkeeping (§ 280.34)

D. Release Detection

1. Overview

2. Section-by-Section Analysis

E. Release Reporting, Investigation and Confirmation

1. Overview

2. Section-by-Section Analysis

F. Release Response and Corrective Action for UST Systems

Containing Regulated Substances

1. Background

2. Major Issues Influencing the Final Rule

3. Section-by-Section Analysis

G. Out-of-Service UST Systems and Closures

1. Introduction

2. Temporary Closure (§ 280.70)

3. Permanent Closure (§ 280.71)

4. Assessing the Site at Closure (§ 280.72)

5. Applicability to Previously Closed UST Systems (§ 280.73)

6. Closure Records (§ 280.74)

H. Analysis of Other Significant Comments 

1. Reliance on Codes Developed by Nationally Recognized

Organizations 

2. Additional Decisionmaking Authority for Implementing

Agencies

V. Relationship to Other Aspects of the UST System Program

A. Interim Prohibition

B. Notification

C. Leaking Underground Storage Tank Trust Fund

D. Exempted Tank Studies
VI. Relationship to Other Agency Programs

A. CERCLA

B. Hazardous Waste Tank Program 

C. Hazardous Waste Management Regulations

1. Hazardous Substances

2. Petroleum and Petroleum-based Substances

D. Used Oil Regulations

E. SPCC

F. DOE High Level Radioactive Waste Program

VII. Economic and Regulatory Impacts

A. Regulatory Impact Analysis

1. Executive Order 12291

2. Costs

3. Benefits

4. Cost Effectiveness of the Final Rule

5. Economic Impacts on Existing Facilities

6.Integration of Technical Standards and Financial 

Responsibility Rules

B. Regulatory Flexibility Act

1. Small Entities Potentially Affected by the Rule

C. Paperwork Reduction Act

VIII. List of Subjects in 40 CFR Part 280

I. AUTHORITY

These regulations are issued under the authority of sections 

2002, 9001, 9002, 9003, 9004, 9005, and 9006, 9007, and 9009 of the 

Solid Waste Disposal Act of 1970, as amended by the Resource 

Conservation and Recovery Act of 1976, as amended (42 U.S.C. 6912, 6991, 

6991(a), 6991(b), 6991(c), 6991(d), 6991(e), 6991(f) and 6991(h)).
II. BACKGROUND

A. Subtitle I of RCRA

The Hazardous and Solid Waste Amendments of 1984 extended and 

strengthened the provisions of the Solid Waste Disposal Act as amended

by the Resource Conservation and Recovery Act (RCRA) of 1976. One major 

portion of RCRA as amended, Subtitle I, provides for the development and 

implementation of a comprehensive regulatory program for "underground 

storage tanks" containing "regulated substances" and releases of these 

substances to the environment.

Subtitle I defines "underground storage tank" as a tank 

system, including its piping, that has at least 10 percent of its volume 

underground. Throughout this preamble and final rule, the terms 

"underground storage tanks," "USTs," and "UST systems" include both the 

underground storage tank vessel and the underground piping connected to 

it.

"Regulated substances" are defined as substances defined as 

hazardous under the Comprehensive Environmental Response, Compensation, 

and Liability Act of 1980 (CERCLA), except hazardous wastes regulated 

under Subtitle C of RCRA, and petroleum. 

Subtitle I excludes the following from the definition of 

USTs:

oFarm or residential tanks of 1,100 gallons or less capacity 

storing motor fuel for noncommercial purposes;

oTanks storing heating oil for consumptive use on the premises 

where stored;

o Septic tanks;

oPipeline facilities (including gathering lines) regulated under 

the Natural Gas Pipeline Safety Act of 1968, the Hazardous 

Liquid Pipeline Act of 1979, or state laws comparable to 

these Acts;

o Surface impoundments, pits, ponds, and lagoons;

o Storm-water or wastewater collection systems;

o Flow-through process tanks;

oLiquid traps or associated gathering lines directly related to 

oil or gas production and gathering operations; and

oStorage tanks situated on or above the floor of underground 

areas, such as basements and cellars.
Subtitle I contains several major provisions for the 

regulation of UST systems. Section 9002 requires UST system owners to 

notify states of the existence of their UST systems. These notification 

requirements were addressed in a final rule published by EPA on November 

8, 1985 (50 FR 46602). Section 9002, as amended by the Superfund 

Amendments and Reauthorization Act of 1986 (SARA), also requires that 

states use the notifications they receive to compile tank inventories. 

Under federal grant agreements, states are providing EPA with aggregated 

data from these notifications.

Under section 9003, EPA must promulgate regulations 

applicable to all owners and operators of UST systems as necessary to 

protect human health and the environment. In promulgating these 

regulations, section 9003(b) authorizes the Administrator to distinguish 

between types, classes, and ages of underground storage tanks. Section 

9003 requires EPA to issue design, construction, installation, and 

compatibility standards for new tanks, as well as requirements 

applicable to all tank owners and operators concerning leak detection, 

recordkeeping, reporting, closure, corrective action, and financial 

responsibility.

Section 9003(h), as amended by SARA, gives EPA--and states 

under cooperative agreements with EPA--authority to clean up petroleum 

releases from UST systems or to require their owners and operators to do 

so. It also establishes a trust fund to finance these activities.

Section 9004 permits EPA to authorize states to implement 

their own UST programs in place of the federal requirements if the 

state's requirements are "no less stringent" than EPA's and provide for 

adequate enforcement. Programs which are less stringent in certain 

areas may receive approval for an interim period.

Other provisions of Subtitle I pertain to definitions

(section 9001); entry, inspection, and information gathering (section 

9005); enforcement (section 9006); federal facilities (section 9007); 

state authorities (section 9008); and studies and reports to Congress 

required of EPA (section 9009).

This preamble and final rule pertain to the requirements 

mandated by sections 9003(a), (c), (e) and (g); they also meet the study 

requirements of sections 9009(a) and (b). Final rules for state program 

approval requirements, under section 9004, are found elsewhere in 

today's FEDERAL REGISTER. Final rules for financial responsibility 

requirements for petroleum UST systems, under sections 9003(a) and (d), 

will be promulgated by EPA at a later date.

Section 9003(c) requires EPA to establish the following 

minimum technical requirements for all UST systems: to maintain a leak 

detection system or comparable system designed to identify releases to 

protect human health and the environment; to maintain records of any 

such release detection system; to report releases and corrective action 

taken; to take corrective action in response to a release; and to close 

tanks to prevent future releases. Under section 9003(e), EPA must also 

establish performance standards for new UST systems. At a minimum, 
these standards must include design, construction, installation, release 

detection, and compatibility standards.

Until the promulgation of today's final rule, section 9003(g) 

established an "Interim Prohibition" that allowed installation of UST 

systems after May 8, 1985, only if the UST system is protected from 

corrosion, prevents releases due to corrosion or structural failure for 

the operational life of the tank, and is constructed of material 

compatible with the substance to be stored. The law allowed an 

exemption from the requirement of corrosion protection if an UST system 

is located at a site having a soil resistivity measured at 12,000 

ohms/cm or greater. An interpretive rule concerning the Interim 

Prohibition was published on June 4, 1986 (51 FR 20418). These Interim 

Prohibition requirements are replaced by today's final rule for new tank 

standards, except in those few cases where the Agency has decided to 

defer regulatory action on some types of UST systems. For these 

deferred UST systems, the Interim Prohibition will continue to apply 

until EPA takes action in the future either to regulate or not regulate 

them (see §§ 280.10 and 280.11 of the final rule).

B. Operating Principles

Faced with the mandate of Subtitle I, EPA recognized several 

unusual aspects of the regulated universe that have created special 

problems in developing an effective regulatory approach. First, the 

regulated universe is immense, including over 2 million UST systems 

estimated to be located at over 700,000 facilities nationwide. Second, 

over 75 percent of the existing systems are made of unprotected steel, a 

type of tank system proven to be the most likely to leak and thus create 

the greatest potential for health and environmental damage. Third, most 

of the facilities to be regulated are owned and operated by very small 

businesses, essentially "Mom and Pop" enterprises not accustomed to 

dealing with complex regulatory requirements. Fourth, numerous 

technological innovations and changes are now underway in various 

sectors of the UST system service community.

In response to the unique aspects of this regulated 

community, and the clear need for comprehensive management of USTs 

during their operating life, EPA has identified and followed several key 

operating principles, described briefly below, in developing the final 

regulations for USTs. 

oThe UST program must be based on sound national standards that 

protect human health and the environment.

oThe UST regulatory program must be designed to be implemented at 

the state and local levels. State and local governments have 

been and continue to be the authorities most capable of 

effective oversight of UST systems and response to releases.

oThe regulations must be kept simple, understandable, and easily 

implemented by the owner and operator in order to facilitate 

voluntary compliance. Section 9003(b) specifically indicates 
that technical capability can be considered in developing the 

Subtitle I rules.

oThe regulations must not inhibit new UST technological 

developments.

oThe regulations must be designed to retain the flexibility 

necessary to accommodate, where possible, the special needs 

of the UST regulated community, which is largely composed of 

small businesses with limited resources available for capital 

improvements. 

oIn order to encourage the utmost voluntary compliance, the 

regulations should build upon current industry trends and tie 

into and utilize ongoing industry initiatives toward more 

sound UST management. Towards this end, Section 9003(b) 

specifically authorizes EPA to consider industry practices 

and consensus codes in developing appropriate UST 

regulations. The Agency expects the nationwide use of these 

new management practices to yield direct environmental 

benefits.

By reflecting these operating principles in the final UST 

regulations, the Agency believes it has taken the most effective 

approach toward protecting human health and the environment.

C. Summary of April 17 Proposed Rule

On April 17, 1987, EPA proposed regulations for USTs storing 

either petroleum or hazardous substances (other than hazardous wastes 

regulated under Subtitle C of RCRA) (52 FR 12662). These proposed 

regulatory measures set requirements for both new and existing UST 

systems to control the major causes of releases from these tank systems 

and included, among other things, corrosion controls, proper 

installation requirements, and spill and overfill prevention measures.

Figure 1 illustrates several key aspects of the regulatory 

program proposed in April 1987; requirements for corrosion protection 

and monthly release detection at all new UST systems; the phase-in of 

either monthly release detection or periodic tightness testing combined 

with inventory control at all existing USTs, within 3 years if 

unprotected from corrosion and within 5 years if protected; and the 

upgrading of all existing UST systems to the new tank standards within 

10 years. In addition, the proposed new and upgraded tank standards for 

hazardous substance USTs required secondary containment with 

interstitial monitoring.

[INSERT FIGURE 1 HERE.]

Figure 1 does not illustrate several other requirements and 

standards proposed for both new and existing UST systems: the design 

and installation of new UST systems; spill and overfill prevention; UST 

system repair; system closure; release detection methods and 
performance; and release confirmation, reporting, and response 

(including corrective action requirements). These proposed requirements 

and the manner in which they may have changed in the final rule are 

described in detail later in today's preamble. Several major points of 

departure from the proposal are identified and discussed in section III. 

below.

D. Public Comment on the Proposal

EPA received over 5,000 individual comments from over 1,100 

commenters on the April 17 proposal, including verbal and written 

comments from the three public hearings. In general, these public 

comments supported the Agency's overall approach to the proposed 

regulations and the substantive requirements for new and existing UST 

systems.

Many comments addressed specific parts of the proposed rule, 

suggesting changes or calling attention to potential problems. These 

specific comments are discussed below in today's preamble. In summary, 

many comments tended to center on three areas: concern for the impact 

the UST rule would have on small businesses, calls for for EPA to adopt 

more stringent requirements for certain sensitive areas, and suggestions 

on the best way to phase in release detection. (See the corresponding 

sections in today's preamble for a full discussion of these comments.) 

The financial responsibility requirements generated more public comment 

than any other single area. Comments on this issue will be addressed in 

the financial responsibility final rule that will appear in a later 

FEDERAL REGISTER.

E.Summary of the Supplemental Notice and the Notice of Availability of 

New Information

After the April 17 proposal appeared, EPA realized that some 

aspects of the technical standards needed to be clarified and that more 

public comment on these matters was needed. Consequently, EPA published 

a Supplemental Notice on December 23, 1987 (52 FR 48638). This 

Supplemental Notice dealt with four areas pertaining to the proposed 

technical requirements:

(1) Use of "static inventory control" to monitor used oil UST 

systems;

(2) A listing of substances subject to petroleum UST 

standards;

(3) Alternatives to release monitoring for piping and tanks

protected from external corrosion; and

(4) An alternative definition of "flow-through process tank."

Public response concerning these issues is discussed in later sections 

of this preamble.
On March 31, 1988, EPA published a Notice of Availability of

additional information for public comment. It announced the 

availability of information pertaining to several technical areas of the 

proposed rule including general operating requirements, release 

detection and tank closure. This new information was submitted by 

commenters, gathered in meetings or conferences and produced by Agency 

research programs. Few public comments were provided concerning these 

documents.

F. Influences on the Final Rule

In the preamble to the April 17 proposal, the Agency 

discussed the scope and nature of the problem posed by UST systems and 

several important influences on the development of the proposal (52 FR 

12665-12671). Today's final rule builds on that earlier information and 

has benefited from numerous comments provided by the public on the 

issues highlighted in the proposal. The following section briefly 

discusses several areas that have received further consideration from 

EPA in the development of today's final rules.

1. Scope of the Problem

The preamble to the proposed rule (52 FR 12665) presented 

estimates of the number of leaking UST systems based on EPA studies, 

local government experiences, and industry estimates. Among the 

statistics cited were the percentage of systems failing tightness 

testing, the percentage of systems actually leaking, the correlation of 

tank age to failure, and the extent and impact of soil and ground-water 

contamination from USTs. After the proposed rule was issued, EPA 

completed an additional study of the causes of release from UST systems. 

This new study was placed into the public docket and announced as 

available for comment in the December 23, 1987, Supplemental Notice. 

This study, "Causes of Release from UST Systems," and the public 

comments on it were important in developing today's preamble and final 

rule.

a. Current Estimates of "Non-Tight" UST Systems

In the preamble to the proposal (52 FR 12665), EPA cited 

evidence that numerous UST systems are non-tight and may be leaking. 

This evidence was based largely on three studies: EPA's "Underground 

Motor Fuel Tanks: A National Survey" reported tank tightness testing 

results and found that 35 percent of over 450 tank systems surveyed 

nationwide failed tightness testing; Suffolk County's UST program data 

revealed that 26 percent of over 6,000 tank systems tested in this New 

York county failed; and a Chevron-sponsored testing program found that 

nearly 10 percent of over 3,000 of their UST systems failed.

Commenters responding to the proposal who had experience with 

tightness testing provided various claims that between 11 and 48 percent 

of existing UST systems failed under test conditions. In an EPA-
sponsored meeting, a group of experienced, independent installation 

contractors expressed their expert judgment that increased awareness of 

the UST problem, use of better tanks, and use of better installation and 

maintenance procedures have decreased the probability of present-day 

systems testing non-tight to about 20 percent, in contrast to the 50 

percent of UST installations they believed would have tested non-tight 

several years ago.

After publication of the proposal, EPA studied several 

additional pieces of information concerning causes of release from UST 

systems. For example, EPA further reviewed the records of over 10,000 

tightness test results from local UST programs (in Suffolk County, New 

York; Austin, Texas; and San Diego, California). EPA also analyzed an 

extensive and detailed historical set of records from a Texas tank 

testing company (the Service Station Testing Company of San Antonio, 

Texas). The EPA-sponsored report, "Causes of Release from UST Systems," 

is based on all these data and concludes that approximately 25 percent 

of existing UST systems are found to be non-tight when tested using 

current methods and that loose tank fittings or faulty piping causes 84 

percent of these tightness test failures. Figure 2 summarizes the 

Agency's findings concerning the causes-of-release profile as derived 

from tank testing results and documented follow-up at over 10,000 UST 

systems conducted nationwide.

[INSERT FIGURE 2 HERE]

b. Estimated UST Systems with Releases

Current indications concerning the number of UST systems 

nationwide that have had releases in the past or are now leaking are 

less precise than the tank tightness data, but the Agency believes the 

information that is available is significant nonetheless. As discussed 

in the preamble to the proposed rule, in many places in the nation that 

are still without state or local UST regulatory programs today, release 

detection only takes place when someone sees or smells the release (52 

FR 12665). These historical data suggest that only about 10 percent of 

release incidents in these areas are discovered by inventory controls or 

mechanical release detection methods. Although the large number of 

incidents that are known to threaten or have contaminated ground-water 

wells is significant, it is not an accurate prediction of leaking UST 

systems because most UST systems are not located near wells.

As the result of aggressive UST monitoring programs in two 

states, over 5,000 UST sites in California and 3,000 sites in Florida 

have been identified as having had releases during the past three years. 

These recent discoveries already exceed 10 percent of the number of UST 

sites in each of these states, and the number of releases identified in 

just these two states may soon exceed the cumulative total of releases 

reported to all the states up until 1985 (see 52 FR 12665). At a more 

local level, UST system programs in Dade County, Florida, and San Jose, 

California, have also identified (through required release detection and 

system closure procedures) that well over 10 percent of their UST 

facilities have had some noticeable or significant releases into the 

surrounding soil and groundwater. Thus, the initial findings by state 
and local UST regulatory programs that are particularly aggressive 

appear to corroborate an industry-sponsored study (than previously cited 

Chevron investigation) that found approximately 10 percent of their 

1,000 UST facilities located throughout the South and Southwest of the 

United States have had an adverse impact on nearby ground water in the 

form of released product floating on top of the ground-water table (see 

52 FR 12666).

Public comments received in response to the proposal 

concerning this subject are not conclusive. Some industry sources 

provided very low estimates, claiming that from 0 to 3 percent of UST 

systems have had releases. Others claimed the actual number of leaking 

tank systems could be as high as 50 percent in some areas. Many 

estimated that the actual range is somewhere between 8 to 20 percent of 

UST sites, and the average of all estimates reported by commenters falls 

into this range. As shown in the previous figure (Figure 2), 

approximately 25 percent of all systems are now testing as non-tight. 

About 15 percent of the sites whose systems were tested actually proved 

to have a leak under normal operating conditions (tank and delivery 

piping leaks), and this proportion falls within the above-estimated 

range provided by the commenters.

Some commenters attempted to provide additional insight into 

the relationship between tank age and failure by indicating that tanks 

begin to fail tightness tests (and leak) at a much greater frequency 

after 12 years. In addition, the recent EPA causes-of-release study 

includes one study that indicated 10 to 13 percent of the tanks that are 

12 to 13 years old were non-tight. This is more than double the 

proportion of non-tight tanks tested in other age groups. In another 

study, of the tanks actually found to be leaking, 42 percent of the 

leakers were 15 to 20 years old, and 30 percent of the leakers were 10 

to 15 years old. All of the tanks that were leaking were made of bare 

steel. This demonstrates that the critical age in a typical unprotected 

steel tank's life is the period between 10 to 20 years of age when 

breakthrough from corrosion is most likely to begin.

Some commenters disputed the severity of the threat posed to 

the nation by leaking UST systems, which was discussed in the preamble 

to the proposed rule. For example, one suggestion was that the data 

presented in the preamble indicate less than 0.008 percent of the total 

area of the United States is affected by contamination due to leaking 

UST systems. In general, EPA finds this line of reasoning unpersuasive. 

In particular, this argument ignores, (1) that population density in 

the nation is not uniform (with most areas being sparsely populated or 

unpopulated); (2) that tank systems are generally located near populated 

areas to provide the fuel for these centers of human activity and; (3) 

that there are numerous documented cases of drinking water wells that 

have been threatened or already destroyed by leaking UST systems 

nationwide. The dispersal of leaked contaminants within ground-water 

aquifers can also affect an area many times larger than the soilcontaminated area. Further information gathered over the coming years 

of UST program implementation will ascertain the full magnitude of the 

impacts that leaking UST systems pose in terms of contamination to the 

nation's environment, but EPA concludes that the evidence collected to 
date, including the information provided by commenters on the proposal, 

clearly supports the need for today's final rules.

2. New Cause-of-Release Information

EPA's new information concerning releases from UST systems 

comes primarily from public comment and an EPA-sponsored study ("Causes 

of Release from UST Systems") that was made available for public comment 

in the December 23, 1987, Supplemental Notice. Review of this 

information has resulted in the following findings concerning the major 

causes of releases today:

oMost releases do not come from the tank portion of UST systems, 

because piping releases occur twice as often as tank 

releases;

o Spills and overfills are the most common causes of releases; 

oVarious nonoperational UST components at the top of USTs are 

loose and leak in the event of overfills; 

oAlthough the older bare steel tanks fail primarily by corrosion, 

the "new generation" USTs (i.e., coated and cathodically 

protected steel, fiberglass-clad steel, and fiberglass tanks) 

have nearly eliminated failure induced by external corrosion;

oCorrosion, poor installation techniques and workmanship, 

accidents, and natural events (e.g., frost heaves) are the 

four major causes of failure for piping; and

oWhen piping fails, pressurized systems pose a significant added 

threat of sudden, large releases.

Thus, the major causes of releases from UST systems are due 

to failures of unprotected tanks, leaks in delivery piping, leaks from 

vent pipes and fittings on top of the tank, and spill and overfill 

errors. Comments received on the original proposal (52 FR 12665-12668) 

and the Supplemental Notice concerning causes of release generally tend 

to corroborate the above findings. The following information summarizes 

some of the most relevant findings that are important in guiding today's 

standard-setting.
a. Tanks

Most existing tanks are made of bare steel. Numerous tank 

failure histories indicate that when bare steel tanks fail they almost 

always do so because of external corrosion. Of all of the current 

causes of release, corrosion of bare steel (tanks and pipes) is by far 

the most important.

Tank manufacturers have responded to this problem with a "new 

generation" of tanks. Innovative tanks began to appear about 20 years 

ago in the United States in three basic forms: fiberglass-reinforced 

plastic (FRP); steel with a corrosion-resistant coating and cathodic 

protection; and steel-FRP composite. A dramatic acceleration in the use 

of new generation tanks occurred with the introduction of the federal 

law's "Interim Prohibition" three years ago. These protected tanks now 

are estimated to account for about 20 to 25 percent of existing USTs. 

Although "new" in terms of protective designs, some of each of the new 

types of tank systems have been in the ground for over 20 years. 

Reported failures observed in the field due to corrosion (or other 

reasons) are very rare.

Failures (leaks) at all existing FRP tanks appear to have 

occurred at less than a rate of 0.05 percent per year of the total FRP 

tanks installed nationwide. Many commenters and other sources support 

the field estimates collected by EPA that less than 0.5 percent of the 

total number of existing FRP tanks have ever leaked. Although some 

installation-related failures have occurred in the past, heightened 

installer awareness of proper practices and techniques appropriate to 

FRP technology, manufacturer-sponsored contractor education programs, 

and production quality assurance appear to be responsible for a 

consistently decreasing failure rate of FRP tanks. The most important

reported failure mode for these tanks is improper installation 

practices.

One new tank type, the STI-P3, is a favorite of corrosion 

engineers. These steel tanks have an external noncorrodible coating and 

a factory-applied metal anode that sacrifices itself to protect any bare 

spots on the tank, and the tank vessel is electrically isolated from any 

attached piping. Very few failures have ever been reported, and those 

failures are due to installation damage or improper maintenance, not 

design. In Ontario, Canada, where STI-P3 tanks have been widely used, 

the number of tank releases due to corrosion is reported to be declining 

as old tanks are replaced with STI-P3 tanks.

The steel-FRP composite tanks have not been used as widely as 

either the FRP or coated and cathodically protected tanks described 

above. Approximately 65,000 have been installed in this country. No 

corrosion-related failures have been reported. Many commenters 

suggested that this type of tank has several advantages over both FRP 

and coated and cathodically protected steel tanks, such as durability, 

no need for maintenance, and an added barrier between the tank and the 

environment should the steel tank be breached by internal corrosion.
As the threat of external corrosion is reduced by new tank 

designs, internal corrosion may eventually become the primary cause of 

failure for steel tanks. Internal corrosion, however, occurs far less 

frequently and takes longer to manifest itself than external corrosion. 

Many commenters have reported problems with internal corrosion under 

the drop tube (i.e., fill pipe located within the tank) of steel tanks. 

Data submitted from the tank lining industry confirm these reports. 

The tank manufacturing industry, however, began to respond to this 

problem several years ago by including "striker plates" under all 

openings of their new tanks.

Lining tank interiors is another way to prevent releases due 

to internal and external corrosion. Tank interior lining has been 

employed by major corporations and small businesses both as a short-term 

solution for potentially leaking tanks and as a preventive measure for 

temporarily giving structurally sound, non-leaking existing tanks the 

same protection from corrosion-induced releases that "new generation" 

tanks have. Data indicate this to be a successful procedure for 

extending an existing tank's operational life. Even when employed in 

the absence of external cathodic protection, failure rates are reported 

to be very low, apparently because current industry consensus codes only 

recommend the use of lining when the tank shell is assessed to be able 

to withstand the expected rate of corrosion at the site (determined by 

assessing the tank's existing condition).

b. Piping

Most commenters rated delivery piping the most significant 

source of releases and reported releases occurring twice as frequently 

from piping as from bare steel tank releases. Two types of piping 

systems are commonly used: suction piping, which is used in low-volume 

applications where only a few dispensers are needed; and pressurized 

piping, which is used in high-volume applications where many dispensers 

are fed from one tank. Each piping system has unique advantages and 

disadvantages, discussed below.

Suction piping is considered by commenters to be safer than 

pressurized piping because it operates at less than atmospheric 

pressure. If the pipe develops a leak, air or ground water is usually 

drawn into the pipe instead of product leaking out. Commenters 

suggested, however, that suction piping systems do not operate 

efficiently in a number of settings, such as at high altitudes, in hot 

climates, or in high-volume delivery situations.

Pressurized piping systems reportedly are used at about 95 

percent of new retail motor fuel system installations. If the delivery 

line is breached, free product is released until the pressure in the 

pipe equals the pressure outside the pipe. Without add-on 

instrumentation or devices, large volumes of product can be pushed out 

of breaches in the piping when product is delivered to the pump. 

Pressurized piping simply pushes more volume to meet this increase in 

demand, releasing large amounts of product quickly into the environment.
Comments received by EPA indicate that the releases from 

pressurized piping systems can be catastrophic in the absence of 

monitoring and automated pump flow restriction devices. Incidents 

involving releases of thousands of gallons have been reported to EPA by 

experienced installers. It is estimated that at least 70 percent of the 

volume of product lost through pressurized pipe releases could be 

avoided by retrofitting each line with a simple, inexpensive, continuous 

in-line pressure monitor that automatically restricts product flow in 

the presence of a significant line leak.

Both suction and pressurized piping are often damaged by 

external corrosion. Cathodic protection of steel piping would 

significantly reduce corrosion failures. Presently, most steel piping 

is protected by galvanizing and coating, or coating and wrapping. The

threaded portions at joints are the most common failure points because 

the protection is removed from them while threading and is never 

replaced. In these cases, cathodic protection would reduce joint 

failures. Other joint failures result from untightened joints, crossthreaded joints, or improperly made joints. Improving the installer's 

education and skills in the complex task of pipe installation would 

reduce these piping failures.

Also, installers and others have estimated that piping is 

damaged 10 percent of the time at new installations between the 

installation of equipment and completion of paving. They strongly 

recommend that a test of new equipment before start-up is essential as a 

sound practice, particularly with pressurized piping.

Natural forces and accidents also cause piping failures. The 

piping is near the surface of the ground and, thus, subject to frost 

heaves and overloading. In addition, the starting and stopping of 

product delivery causes the piping to move and shift. This eventually 

causes joint failure in many piping systems. "New generation" piping 

systems comparable to the "new generation" of tanks are under 

development but not widely used.
c. Nonoperational Components 

Nonoperational components consist of tank bung holes, tank 

manholes, vent and fill lines, vapor recovery lines, and manifold piping 

(the piping used in connecting tanks together). These components, all 

located above the top of the tank, are called nonoperational because 

releases from these sources do not occur under normal operating 

conditions. Releases from them are usually unseen because they are 

underground. These releases are episodic and usually of small volume, 

because they only occur when the tank is overfilled or when manifolded 

tanks are filled through the piping connecting the tanks together. 

Generally, when an overfill occurs, the volume of product contained in 

the fill tube above the loose nonoperational component will be forced 

out into the environment until the product level in the UST drops below 

the leaking component. These leaking, nonoperational components are 

reported to be most often caused by improper installation practices, 

such as loose bung hole plugs not being tightened at installation or 

vent lines being hand-tightened on top of the tank.

Two solutions are available to stop this type of release: 

either ensure proper installation of these different types of fittings 

or eliminate overfills. Elimination of overfilling of the tank is the 

surest remedy and is probably the easiest to accomplish with overfill 

shutoff devices now widely available. Most releases associated with 

nonoperational components would be prevented if overfills were 

successfully eliminated.

d. Spills and Overfills

In addition to episodic releases from nonoperational 

components, there is an even more prevalent source of release that takes 

place at the tank fill port during tank filling. Although usually small 

in volume, spill and overfill releases are probably the most common 

causes of release from UST systems. These releases usually occur at the 

surface of the ground around the top of the fill pipe when the delivery 

truck's hose is disconnected from the fill pipe. Most of these releases 

go unreported due to the typically small volume of product lost

(generally, less than the volume of the delivery truck's hose). Most 

excavated bare steel tanks, however, show evidence of spilled material, 

such as dissolved asphalt coating near the fill pipe. Regulatory 

officials in Dade County (Florida) cite spills and overfills as the 

primary cause of release--45 percent of reported releases. These 

surface releases are at least twice as numerous as tank or piping 

releases.

Spills most often occur at the fill pipe opening when the 

delivery truck's hose is disconnected, usually releasing only a few 

gallons. Overfills occur far less frequently but usually release much 

larger volumes. Overfills generally result in a release from loose, 

nonoperational components located above the tanks (as discussed in the 

previous section ), or from the top of the tank's vent pipe as product 

is forced out during overfilling of the system. Experienced 

installation contractors emphasize to EPA that the control of spills and 
control of overfills are two different problems and equipment that 

controls one may not control the other.

3. Industry Codes and Practices

In the preamble to the proposed rule (52 FR 12670), EPA 

identified numerous industry consensus codes and recommended practices 

that influenced the development of the proposed regulatory program. A 

table was provided listing several codes and practices concerning the 

proper management of UST systems that have been developed, mostly in the 

past decade, by industry associations, nationally recognized 

professional organizations, and independent testing laboratories. Since 

the proposal of the federal rule over a year ago, these consensus codemaking groups and industry standard-setting activities have continued at 

an increased rate. (Refer to section IV.H.1. for a more detailed 

discussion clarifying the use of codes developed by nationally 

recognized organizations or independent testing laboratories.) 

Table 1 reflects a sampling of the current status of this 

national consensus code-making network. The codes and standards marked 

with an asterisk have been reviewed, updated, or revised over the past 

year. For example, last summer, the American Petroleum Institute 

reviewed several of its recommended practices (e.g., API 1631 and 1615) 

and improved the guidance provided in these documents. In addition, 

several new codes are now under development or have been recently added. 

For example, the National Leak Prevention Association was formed and 

developed an industry consensus code for the interior lining of tanks 

(NLPA 631).

[INSERT TABLE 1 HERE.]

Table 1 provides a snapshot of the depth and scope of the 

collective wisdom that has developed over the past several years in the 

United States concerning the proper standards for UST systems. The 

recent updates and additions to this list of industry consensus codes 

and recommended practices reflect what appears to be a resurgence of 

interest in several areas of sound UST management practices. Numerous 

commenters on the proposal cited specific developments in these 

consensus codes and provided copies of some of the most recent codes 

that were added or updated and revised. In general, they provided a 

reminder to EPA that this improving body of knowledge should be 

understood and considered during the development of today's final rule.
4. Industry Trends

The nature and extent of the public response to the proposal 

has generally confirmed that a significant level of voluntary industry 

upgrading and replacement programs is already underway. The closure and 

replacement trends briefly discussed in the preamble to the proposal (52 

FR 12671) were confirmed by some commenters. Numerous major oil 

companies, independent marketers of retail motor fuel, transportation 

fleet operators (government and private), and various manufacturers with 

USTs have clearly embarked on their own UST system management programs 

before promulgation of today's final rule.

One of the most encouraging trends has been the increasing 

use of protected UST systems nationwide. EPA estimates that there are 

currently over 450,000 UST systems in use today that are protected from 

external corrosion. This expanding use of an important and necessary 

approach to the prevention of releases has increased rapidly over the 

past three years, particularly after the Interim Prohibition went into 

effect in May 1985 (section 9003(g) of RCRA), making illegal the 

installation of bare steel UST systems. EPA estimates that, during the 

past three years over 50,000 new protected tanks were installed 

annually. To date, over 210,000 FRP tanks, 120,000 coated and 

cathodically protected tanks, and 65,000 steel-FRP composite tanks have 

been installed. In addition, an estimated 70,000 tanks have had their 

interiors lined to prevent releases, and another 50,000 UST systems are 

estimated to have been provided with field-installed corrosion 

protection systems. According to tank manufacturers, the number of new 

bare steel tanks installed over the past three years has dropped 

precipitously.

Early findings from several local UST programs visited by EPA 

staff since the proposal have confirmed the beginnings of an accelerated 

rate of closure of old, substandard UST systems (for example, in Suffolk 

County, New York; Austin, Texas; Dade County, Florida; and Sunnyvale, 

California). A rapid rate of closure appears to manifest itself when 

each of these, and several other, local UST programs initiate their 

release detection requirements. Thus, EPA's earlier projections that as 

much as three-fourths of the existing UST universe will be closed, 

upgraded, or replaced to the requirements of the Interim Prohibition 

within 10 years appears to be realistic (52 FR 12671). Today's final 

rule will further ensure that these positive changes are accomplished 

and increased.

EPA believes these are important developments because the 

successful implementation of this program depends a great deal on the 

regulated community's voluntary compliance. The Agency is convinced 

that the most wide-spread compliance will be facilitated by technically 

sound standards that are capable of easy implementation by a highly 

varied regulated community. Thus, as much as possible, the federal 

technical requirements must rely on familiar industry codes and build on 

recognized and effective trends occurring in the field of UST management 

that are consistent with protection of human health and the environment.
5. UST System Technology Development

As discussed in the preamble to the proposal, the array of 

technical control options available to address causes of releases, as 

well as response to releases that occur, also appears to be growing. 

Numerous commenters provided technical information to EPA about newly 

available equipment being marketed for use in the prevention, detection, 

and correction of releases from UST systems. New equipment for use 

either inside or outside of the UST system to detect releases from the 

underground tank or attached piping is being introduced for sale at many 

trade shows and industry fairs nationwide, including less expensive 

methods for providing secondary containment with interstitial monitoring 

for both existing and new UST systems.

Several new types of equipment capable of preventing spills 

and overfills appear to be less costly and more easily retrofitted to 

existing tanks than earlier models. For example, several new models of 

line leak detectors have recently been introduced to the UST market that 

are more sophisticated and sensitive than older types of equipment. In 

addition, numerous companies have contacted EPA about their development 

efforts in the area of retrofitting preventive devices onto existing 

tanks or refurbishing old tanks. Makers of nylon tanks are in the 

process of soliciting the approval of Underwriters Laboratories of 

Canada in that country. Finally, vapor gas vacuum extraction techniques 

for use in the subsurface cleanup of volatile substances are also under 

accelerated development and investigative use in several places 

nationwide. This cleanup technique has reportedly had widespread use in 

West Germany for a number of years.

In summary, business in the UST control technology sector 

appears to be booming, and invention is proceeding at a rapid pace. All 

this activity is a good indication that in the future, simpler, cheaper, 

and more dependable equipment will be produced to aid in the prevention, 

detection, and correction of releases. Experienced persons in UST 

management in the public and private sectors have told EPA staff that 

the current level of control technology development by far exceeds any 

previous efforts within this industry. In order to avoid interfering 

with this ongoing development of innovative and more environmentally 

protective new technologies, the Agency has chosen to write regulations 

that allow room for these new developments. 

6. Leaking USTs Present a Unique Regulatory Challenge

EPA believes its approach to setting standards for UST 

systems on a national scale will have to be different from most national 

environmental programs because the UST problem is significantly 

different. This difference is mainly due to three factors: the large 

number of facilities to be regulated, the comprehensive scope of the 

regulations, and the nature of the regulated community.

The most significant problem is the sheer size of the 

regulated community. Nationally, over 700,000 UST facilities account 
for about 2 million UST systems, an average per state of about 14,000 

UST facilities and 40,000 UST systems. Estimates indicate that roughly 

75 percent of existing UST systems are unprotected from corrosion. In 

addition, because a relatively high proportion of UST facilities (10 to 

30 percent) already have had a leak, or will soon leak unless measures 

are taken to upgrade them, the average number of leaking UST systems may 

range from 1,400 to 4,200 per state in the near future.

The large number of tank owners and tank systems has also led 

EPA to conclude that the final federal UST standards must include a 

phase-in period for certain requirements that apply to existing tank 

systems. Although all federal requirements are in effect immediately 

for new tanks, owners and operators will have additional time to upgrade 

existing tank systems to the corrosion protection standard for new UST 

systems, and to install release detection equipment for existing UST 

systems. This phased-in approach is needed to establish a reasonable 

schedule that recognizes the limited capability of 700,000 UST owners 

and supporting service and manufacturing industries to respond 

immediately to new national regulations, and provides sufficient 

flexibility for implementing agencies. The experience of states that 

have already been operating UST regulatory programs is that it takes 

several years for most owners or operators of existing UST systems to 

understand, plan, and arrange for the purchase, scheduling, and 

installation of necessary services and equipment required by the 

regulations. The phase-in approach also has the added benefit of 

allowing time for continued development and improvement of available 

technologies in the marketplace for prevention and detection of releases 

from UST systems (as discussed previously in this section of the 

preamble).

In addition, today's final rule establishes comprehensive 

requirements for the management of a wide range of UST systems. These 

final standards for UST systems are designed to reduce the number of 

releases of petroleum and hazardous substances, increase the ability to 

quickly detect and minimize the contamination of soil and ground water 

by such releases, and ensure adequate cleanup of contamination. To do 

this, the standards in some way must affect every phase of the life 

cycle of a storage tank system: selection of the tank system; 

installation, operation and maintenance; closure and disposal; and 

cleanup of the site in cases of product release. As a result, these 

standards must be technically adequate to ensure the wide array and 

needed level of improved performance when implemented. At the same 

time, these wide ranging requirements must be straightforward enough to 

be understood and to be carried out successfully hundred of thousands of 

times nationwide.

A third problem is the nature of the regulated community. A 

large proportion of USTs are owned by small businesses with $500,000 or 

less in total assets. For example, 72 percent of all retail motor fuel 

outlets are owned by small businesses. An important influence in the 

making of today's technical standards has been EPA's attempt to minimize 

the regulatory impact on small businesses without compromising the 

statutory requirements to protect human health and the environment. 

EPA's efforts to minimize the regulatory impact are discussed in a 
Regulatory Flexibility Analysis conducted for this rule, as specified by 

the Regulatory Flexibility Act of 1980, and a summary of that analysis 

is presented later in this preamble.

Specifically, the Agency is convinced that the national UST 

standards must be kept simple and implementable by state and local 

officials because many UST facilities are owned and operated as small 

local businesses, such as "Mom and Pop" gasoline service stations and 

convenience stores. These small entrepreneurs, who are used to 

operating their business with minimal regulation, will be significantly 

affected by environmental regulations for UST systems. The experience 

of state and local agencies with UST programs is that large national 

businesses that own tanks are generally willing and have already begun 

to comply with UST requirements. Owners of small businesses, however, 

generally need constant reminders and technical assistance to bring them 

into compliance. Given the nature of this regulated community, a 

regulatory program often will be most effectively carried out by the 

level of government closest to the problem, and thus able to respond 

quickly and to create a visible presence.

7. Emerging State and Local UST Programs and EPA's Approach to 

Regulation

Many states and localities have adopted requirements 

applicable to UST systems. Although these state and local requirements 

are diverse and vary in stringency, EPA believes that the formulation of 

federal standards should build upon the many effective state and local 

programs now in operation or about to begin operating in order to 

utilize this reservoir of accumulated UST experience in a way that can 

rapidly develop into a strong federal-state partnership for addressing 

this national concern. Section 9004 also indicates Congressional intent 

that states with effective programs are to play a major role in 

implementing the program.

At least 18 states and hundreds of local programs are 

currently addressing the ground-water contamination and cleanup problems 

posed by leaking UST systems through established regulatory programs. 

Several states, such as California, New York, and Florida, and local UST 

programs such as those in Suffolk County (New York), Dade County 

(Florida), and Austin (Texas), have established specific UST system 

regulations that include standards for design, construction, and 

installation of new UST systems; closure, retrofitting, and repair of 

existing UST systems; and release detection and corrective action 

requirements for all UST systems. EPA believes this type of state and 

local UST program activity nationwide will increase significantly with 

today's promulgation of EPA's technical standards. Similar to the 

experiences in the three lead states identified above, other states will 

begin to wrestle for the first time with the reality of how to implement 

their UST programs. As the dangers posed by existing UST systems become 

more widely known, local UST programs and involvement should increase 

significantly over current levels.
Given the large number of UST facilities, tank systems, and 

potential cleanups needed, EPA is convinced that many aspects of this 

regulatory program will be most effectively carried out at the state 

level of government. Local government involvement in this regulatory 

program will be important. For example, a small city with about 700 

facilities and 2,000 tank systems within its jurisdiction should be able 

to implement a manageable regulatory program. If each of those 700 

facilities installs one new tank during the next five years, that would 

be about three installations per week. If that small city requires a 

city inspector to be present at each installation, an inspector must be 

in the field three times a week for this task alone. In addition, the 

inspector could be required to be present for periodic tank testings, 

closures, upgrading or retrofit, and cleanups.

Confronted with the above implementation realities, EPA has 

developed a more decentralized approach for addressing the realities of 

the national UST regulatory program. This approach is based on several 

critical factors. First, as more and more state and local governments 

become involved, the work of the UST program must be routinely carried 

out in thousands of jurisdictions nationwide. Several operating state 

and local UST programs already report that they are very busy "running 

the store," expressing surprise at the size of the regulated community, 

and that fairly simple tasks must be routinely repeated numerous times 

for the implementing agency to be successful in bringing UST systems 

into, and maintaining, compliance.

Second, visits to several state and local UST programs have 

shown that they have often developed their own unique requirements and 

methods of implementation, adapted to the types of tanks, physical 

environment, and regulated community with which they are concerned while 

they are, at the same time, all geared towards solving similar technical 

problems. They need the flexibility to continue and to improve upon 

approaches which address the specific environmental needs of their 

communities. They have common implementation problems, however, and 

have expressed the need for better technical aids, such as data 

management tools.

Third, many state and local governments that already 

implement UST programs report a significant level of visible on-site 

monitoring, requiring a constant "regulatory presence" to effectively 

ensure this regulated community's compliance with UST requirements. A 

significant environmental gain is achieved through implementation at the 

local level by these individual UST programs. Thus, improving their 

performance will produce maximum environmental benefits and best ensure 

the success of the UST program nationwide. As the head of the 

"distribution system" of UST-related technical information and 

implementation tools, EPA believes that its implementation efforts 

should be focused on serving the network of state and local programs 

through listening to their concerns and helping them solve 

implementation problems with tools that improve the effectiveness of 

their programs.

Finally, EPA believes that a more decentralized approach to 

the federal implementation of the UST program is needed to ensure real 
gains in protection of human health and the environment. Because there 

are so many UST sites nationwide, it would be very difficult to 

establish a credible federal implementation presence through compliance 

monitoring and enforcement at the federal level. A more realistic and 

effective approach is for EPA to provide support tools and guidance to 

state and local regulators that can be used to improve their programs' 

compliance performance.

In adopting this role, the Agency has recognized that it must 

not only establish sound national standards but, more importantly, must 

focus on improving the performance of the state and local implementing 

agencies. Approval of state programs to operate "in lieu of" the 

federal program takes on a new meaning under this approach because it 

becomes a basic soundness test to ensure that the work associated with 

implementation of these state or local requirements will, in fact, cause 

the needed level of improvement in UST system management when carried 

out by the regulated community. The requisite state enforcement 

authority and technical standards must be ensured and will be the focus 

for approval by EPA. Thus, overall successful performance and 

implementation of this new national program is less focused on 

implementing detailed, national technical standards than it is on 

establishing the national UST program in a way that ensures effective, 

environmentally protective programs at the grassroots level and 

improving the performance of these programs over time. EPA's final 

requirements for state program approval are presented in detail 

elsewhere in today's FEDERAL REGISTER.

Thus, in recognition of its approach to UST implementation, 

EPA has attempted to establish final technical standards that are 

protective of health and the environment but, at the same time, are 

simple, understandable and implementable by state and local officials. 

EPA also recognizes that there is often more than one proper way to 

address specific technical problems that are the focus of the final 

regulations. Therefore, the Agency has attempted to identify and offer 

as many effective alternative technical approaches as possible 

particularly where this flexibility can be applied in the future by the 

implementing agencies. In this way, the final technical requirements 

remain focused on the key environmental problems which the implementing 

agencies face. Promoting the network of state and local implementation 

is the best way to ensure that significant protection of human health 

and the environment will be achieved by today's final requirements.

G. Conclusions Since Proposal

EPA has drawn several conclusions from the influences 

discussed above and in the background sections of the preamble to the 

proposed rule (52 FR 12663-12671). Some of these conclusions support 

the direction and emphasis set forth in the proposal, and others 

indicate a need for change in the final rule.

Given the large size of the existing regulated universe and 

the proportion of these UST systems that have leaked or are presently 

leaking, there is a need to finalize today's rules as an important step 
resources. The number of sites needing significant cleanup due to a 

number of poor past UST management practices is expected to be in the 

tens of thousands nationwide.

Cause-of-release information related to unprotected tanks 

supports EPA's proposed approach for upgrading of unprotected tanks. 

The new information, however, indicates a need for more frequent 

monitoring of unprotected tanks than was proposed. By contrast, 

protected tanks appear to need less frequent monitoring than proposed. 

Also, pressurized piping systems need more stringent monitoring than was 

proposed.

Increased activity in the review and improvement of national 

consensus codes supports EPA's proposed reliance on these codes as 

providing the most up-to-date consensus practices and expertise 

concerning what constitutes proper UST system management. The 

nationwide increase in the use of protected systems, the recent number 

of tank closures, and the development of new prevention, detection, and 

corrective action technologies are encouraging. The final rules must be 

designed to foster and take advantage of these trends. They must be 

simple and easily implementable by the regulated community to ensure the 

maximum level of voluntary participation by tank system owners and 

operators. The Agency continues to believe that the size and nature of 

this regulated universe presents several unique regulatory challenges 

that necessitate the phase-in of some of the requirements for existing 

UST systems to ensure that genuine implementation is accomplished.

The continuing and rapid emergence of numerous state and 

local UST programs is expected and will be encouraged by EPA because 

this is where the "real work" of this new national program must actually 

take place. The Agency's approach to UST program implementation must 

start with a technically sound set of national standards. These 

requirements, however, must be kept simple and implementable because 

most improvements in actual UST performance (and protection of human 

health and the environment) are expected to be achieved by working 

closely with state and local governments over time to increase the level 

of the effectiveness of their UST programs.
III. TODAY'S FINAL RULE

This section provides a summary of EPA's final rule. It also 

identifies and describes several major points of departure from the 

proposed rule, several alternative strategies, public comments on them, 

and the Agency's rationale for the direction of the final rule in 

several other key areas. More detailed summaries of all the public 

comments and the Agency's responses to them can be found in the "Comment 

and Response Summaries Background Document" that has been placed into 

the public docket in support of today's final rule.

!iiia!

A. Summary of Today's Final Rule

EPA is today promulgating regulations for underground tanks 

storing either petroleum or hazardous substances other than hazardous 

wastes regulated under Subtitle C of RCRA. These requirements establish 

measures for both new and existing UST systems to prevent, detect, and 

clean up releases from these systems. These final requirements of Part 

280 fulfill the mandates of RCRA sections 9003(a), (c), and (e), and 

sections 9009 (a) and (b). The major elements of today's final rule are 

noted below.

oNew UST systems must be designed and constructed to retain their 

structural integrity for their operating life, in accordance 

with national consensus codes of practice (see Table 1 

provided earlier in this preamble). All tanks and attached 

piping used to deliver the stored product must be protected 

from external corrosion. Cathodic protection must be 

monitored and maintained to ensure that UST systems remain 

free of corrosion.

oNationally recognized industry installation standards must be 

followed in placing new UST systems in service (see Table 1). 

Owners and operators of new USTs must certify that proper 

installation procedures were followed and identify how the 

installation was accomplished.

oOwners and operators of both new and existing UST systems must 

follow proper tank filling practices to prevent releases due 

to spills and overfills. In addition, owners and operators 

of either new or upgraded UST systems must use devices that 

prevent overfills and control or contain spills.

oTanks must be repaired in accordance with nationally recognized 

industry codes (see Table 1). These national codes include 

several tests that must be conducted to ensure quality 

repairs.

oTo close UST systems, industry-recommended practices must be 

followed: the UST system can be removed from the ground or 

left in place after removing all regulated substances and 
cleaning the tank, filling it with an inert substance, and 

closing it to all future outside access (see Table 1). In 

addition, owners and operators must perform an assessment at 

the time of UST closure to ensure that a release has not 

occurred at the site. If a release has occurred, then 

corrective action must be taken.

oRelease detection must be instituted at all UST systems. For 

petroleum UST systems, several methods will be allowed, 

although tank owners and operators must adhere to 

requirements concerning their use. In addition, owners and 

operators must follow special requirements for pressurized 

delivery lines. Petroleum UST systems are not required to 

have secondary containment with interstitial monitoring. All 

new or upgraded UST systems storing hazardous substances, 

however, are required to have secondary containment with 

interstitial monitoring, unless an alternate release 

detection method is approved by the implementing agency. The 

owners and operators must demonstrate to the implementing 

agency that a release detection method will detect releases 

of the stored substance in a manner no less stringent than 

the release detection methods allowed for petroleum USTs and 

that a method of corrective action is available to clean up a 

release of the hazardous substance should one occur.

oGenerally, release detection at existing UST systems must be 

phased in over a 5-year period based on the age of the tank. 

The oldest UST systems (usually unprotected from corrosion) 

are required to phase in release detection within 1 year, and 

the newest tank systems (usually protected from corrosion) by 

the end of the 5-year period. Release detection for all 

pressurized delivery lines must be retrofitted within 2 

years.

oPeriodic tank tightness testing (every 5 years) combined with 

monthly inventory control is allowed at new or upgraded UST 

systems for 10 years after new tank installation or existing 

tank upgrade. After 10 years, monthly release detection is 

required.

oEither monthly release detection or a combination of annual tank 

tightness testing with monthly inventory control is required 

of substandard existing USTs until they are upgraded. 

Existing UST systems must be upgraded or closed within 10 

years of the effective date of the final rule, or within 1 to 

5 years if a release detection method is not available that 

can be applied during the required phase-in period for 

release detection. Upgrading of petroleum UST systems 

includes retrofitting of corrosion protection and both spill 

and overfill controls at all tanks. Upgrading of hazardous 

substance UST systems also includes secondary containment and 

interstitial monitoring or an alternate release detection 

method approved by the implementing agency.
oTank owners and operators must report suspected releases. 

Indications of a release must be reported to the implementing 

agency, including positive results from release detection 

methods, unless the initial cause of the alarm has been 

immediately investigated and the alarm is found to be false. 

After reporting suspected releases, owners and operators 

must perform release investigation and confirmation tests 

and, where a release is confirmed must begin corrective 

action.

oOwners and operators of leaking UST systems must follow measures 

for corrective action. Immediate corrective action measures 

include mitigation of safety and fire hazards; removal of 

saturated soils and floating free product; and an assessment 

of the extent of further corrective action needed. A 

corrective action plan would be required for long-term 

cleanups addressing ground-water contamination, although 

these cleanups could begin upon notification of the 

implementing agency by the owner and operator. Cleanup 

levels would be established on a site-by-site basis as 

approved by the implementing agency.

B. Major Points of Departure from April 17 Proposal

Today's final rule includes four release detection 

requirements that represent significant changes to the proposed rule: 

(1) More frequent tank tightness testing (annual) of 

unprotected tanks during the initial 10-year upgrading period; 

(2) Less frequent monitoring of new and upgraded tanks until 

age 10; 

(3) Phase-in of release detection over 5 years at existing 

tanks based on age; and 

(4) More stringent release detection for all pressurized 

piping systems.

The final requirements in each of these areas, and EPA's rationale for 

revising the proposal, are summarized below and shown graphically in 

Figure 3. The shaded areas indicate the major changes from the proposed 

approach. More detailed discussions of these major points of departure 

are also provided in later sections of today's preamble.

[INSERT FIGURE 3 HERE.]
1. More Frequent Tank Tightness Testing of Existing Unprotected Tanks 

During the 10-Year Upgrade Period

In the proposed rule (§§ 280.40 and 280.41), EPA provided 

owners and operators of existing UST systems without corrosion 

protection with two options for release detection, but only during the 

proposed 10-year upgrade period. The two options were: 1) to perform 

monthly release detection monitoring or, 2) to conduct monthly inventory 

control combined with a tank tightness test every 3 years. The option 

of tank tightness testing (in combination with inventory control) was 

proposed because tightness testing is already widely practiced. The 

proposed frequency of testing every 3 years was based on the Agency's 

belief that the industry could not accomplish testing of such a large 

universe of existing tanks on a more frequent basis because the supply 

of testing services could not respond to such a large demand. 

Several commenters suggested that the proposed tank tightness 

testing alternative be allowed in the final rule but only if the testing 

were required more frequently. EPA now shares the concerns of those

commenters. The Agency is particularly concerned about unprotected 

existing tanks, which have the greatest probability of leaking. New 

information on causes of release has prompted the Agency to believe that 

tightness testing conducted once every 3 years leaves too much time 

between tests during which an unprotected steel tank may develop 

corrosion holes and release product. Therefore, in the final rule the 

Agency requires that tank testing be performed every year during the 10-

year upgrade period, instead of every third year as was proposed. 

Because unprotected steel tank systems pose the greatest threat to the 

environment and public health, EPA believes that increasing the 

frequency of tightness testing will provide better environmental 

protection and is therefore warranted.

With regard to EPA's initial concern that such a frequency 

would be impractical or difficult to achieve, numerous public comments 

were received from the release detection industry indicating their 

belief that more frequent tank tightness testing is feasible. 

Commenters also verified that tank tightness testing is already a 

commonly used release detection method, and its technology and resources 

are currently widely available.

2. Less Frequent Monitoring of New and Upgraded Tanks Until Age 10

EPA's proposed approach for new USTs required either 

frequent-to-continuous (at least monthly) release detection monitoring 

or semiannual tank tightness testing in combination with monthly 

inventory control. The Agency proposed frequent-to-continuous 

monitoring at new tanks because, the more frequently release detection 

is applied, the more likely an actual release will be detected when it 

occurs, as explained in detail in the proposal (52 FR 12720), and thus 

it was believed to be needed to ensure adequate protection of the 

environment and public health.
Several commenters questioned the proposal to require more 

frequent release detection at new protected tanks than at existing 

(older) unprotected tanks. New information on causes of release (see 

section II.F. of the preamble) confirms that new tanks are the least 

likely to leak. The probability of new or upgraded tanks leaking, 

particularly early in their operational lifetime, is extremely low. 

Therefore, the Agency agrees with commenters who suggested that new 

tanks should be allowed to be monitored less often than proposed.

Today's final rule replaces the proposed semiannual tank 

testing with a requirement to conduct tank testing at least every fifth 

year during the first 10 years of the UST's operational life at a new or 

upgraded UST. As proposed, however, tank testing must be used in 

combination with monthly inventory control to be considered an approved 

release detection method. Because long-term experience with tank 

corrosion protection technology is not yet extensive, and because 

existing bare steel tanks rarely fail before 10 years of age, today's 

final rule requires monthly release detection at protected and upgraded 

tanks only after they pass their tenth year of operation.

3. Gradual Phase-in of Release Detection Based on Age

EPA proposed to phase in release detection at existing UST 

systems over a 3-year period for USTs unprotected from corrosion and a 

5-year period for USTs protected from corrosion. This approach was 

proposed because it was believed to be the fastest schedule reasonably 

implementable and would require unprotected tanks (which have the 

greatest potential to leak) to have release detection in place sooner 

than protected tanks. In the preamble to the proposal (52 FR 12677), 

the Agency identified three approaches towards phasing in of release 

detection: (1) a rapid phase-in (over 1 to 2 years), (2) a gradual 

phase-in (over 3 to 5 years), and (3) a class approach requiring a rapid 

phase-in at the most sensitive UST locations and more gradual phase-in 

elsewhere. After considering public comments received on this issue, 

the Agency has decided in today's final rule to retain the gradual 

phase-in approach but to base the phase-in on the age of the UST system, 

with the oldest tanks being required to have release detection first.

The preamble to the proposal solicited public comment on the 

appropriateness of considering tank age, vulnerability of hydrogeology,

distance to drinking water wells, distance to vital ecological systems, 

and any other factors in the selection of a phase-in approach for 

release detection. Most commenters supported the gradual phase-in to 

take place over time periods ranging from 3 to 10 years, but recommended 

that it be based on age. A few recommended the rapid phase-in approach, 

and most of those recommended that the phase-in be based on age.

Today's final rule requires the oldest tanks, with or without 

corrosion protection, to apply release detection within the first year 

and the newest tanks no later than 5 years after the effective date of 

today's rule. This approach is believed to offer several advantages: 

(1) EPA has concluded that the phasing in of release detection at all 

existing UST systems in the large universe is implementable within 5 
years; (2) the age-based sequencing schedule ensures that implementation 

of the requirements will take place in an orderly fashion that will 

spread out the demand for release detection services and avoid 

bottlenecks; (3) it gives higher priority to older, unprotected tanks, 

which have been found to have the greatest potential to leak; and (4) it 

still allows the newer, protected tanks, which are the least likely to 

be leaking, to wait until the fifth year, as did the proposed rule. In 

choosing the gradual approach, the Agency agrees with those commenters 

who cited the rapid approach as being impossible to implement with such 

a large universe of UST systems. In addition, the gradual approach is 

supported by numerous existing industry, state, and local management 

programs which utilize the gradual approach as the most feasible phasein approach. The reasons the Agency is taking this gradual phase-in 

approach are discussed in more detail later in this preamble (section 

IV.D.2.). The class approach was deemed unimplementable for other 

reasons discussed in more detail later in this section of the preamble.

4. More Stringent Requirements for Pressurized Piping

The proposed rule contained release detection requirements 

for pressurized piping in addition to those requirements for new tank 

systems. Specifically, automatic release detection and shutoff devices 

were proposed for the pressurized piping at new tank systems unless 

continuous release detection or interstitial monitoring was installed. 

Suction piping systems were exempt from the proposed requirements if 

other minimum construction requirements were met (see 52 FR 12774). 

Information obtained by the Agency at the time of the proposal indicated 

that 20 to 30 percent of all reported releases are due to piping 

failures. EPA also suspected that pressurized piping systems, which are 

reportedly the most commonly used withdrawal system at new retail motor 

fuel installations, were responsible for the larger releases.

Information obtained by EPA after publication of the proposal 

(see section II.F. of today's preamble) indicates that piping system 

failures are responsible for a much greater percentage (80 to 85 

percent) of release incidents than previously thought. Public comments 

received by EPA confirmed the Agency's belief that failure of 

pressurized piping systems frequently results in large releases.

In today's rule, EPA has set forth more stringent release 

detection requirements for pressurized piping systems. Systems must be: 

(1) equipped with automatic shutoff devices or automatic flow 

restrictors and use either annual line testing or monthly release 

detection monitoring; or (2) have continuous interstitial or vapor 

monitoring combined with either shutoff devices or alarms. These 

requirements will ensure that product releases from the most vulnerable 

portion of the UST systems are minimized. (Today's preamble section 

IV.D.3.b. discusses these requirements more fully.)
C. Alternative Approaches Considered

1. New UST Systems Containing Petroleum

In the preamble to the proposed rule (52 FR 12673-12675), EPA 

described three basic regulatory options that were considered for new 

petroleum tanks: (1) protected single-walled tanks with release 

detection; (2) secondary containment with interstitial monitoring; and 

(3) a class approach under which more protective requirements would 

apply to UST systems located where a release could pose a particularly 

high risk. The Agency solicited comments on each of these general 

approaches to regulate new petroleum tanks, and announced that, based on 

comments received and on any additional data gathered prior to 

promulgation, it would give further consideration to each of them before 

finalizing today's rules. Numerous comments were received concerning 

these options, and EPA developed additional information after the 

proposal that is relevant to this issue. (EPA solicited comment on this 

new information in the December 23, 1987, Supplemental Notice and in the 

March 31, 1988, Notice of Availability.)

Based on EPA's information and on public comment, the Agency 

has decided to proceed with the proposed approach of protected singlewalled tanks with release detection for new petroleum UST systems. The 

Agency's basic rationale for this choice as explained in the preamble of 

the proposal remains unchanged. The following discussion briefly 

highlights some of the concerns raised by commenters and the influences 

that the new information had on this final decision.

a. Option 1: Protected Single-Walled Tanks With Release 

Detection

Several commenters supported EPA's proposed approach of 

allowing protected single-walled tanks with release detection to be used 

at all new petroleum UST systems. They agreed that this approach is 

protective of human health and the environment, confirmed that it is 

already widely in use by industry and in numerous state programs, and 

that it is available as a viable and effective alternative to 

interstitial monitoring.

Some commenters, however, suggested that the approach of 

protected single-walled UST system with leak detection approach is not 

as implementable as secondary containment. They stated that secondary 

containment is a more straightforward technical approach because, in the 

long run, it simplifies implementation by allowing relatively easy 

determination of the UST's compliance status. Another disagreement with 

this option is the belief expressed by some commenters that the 

probability of releases to the environment occurring at single-walled 

tanks with release detection is much greater compared to UST systems 

with secondary containment and interstitial monitoring.

EPA agrees with those commenters who suggested that there 

will probably be more releases to the environment from protected single-
walled UST systems with release detection than from systems equipped 

with interstitial monitoring. One of the advantages of secondary 

containment is the potential for detecting a leak before a release to 

the environment actually occurs. Secondary containment thus provides a 

second barrier against release.

Although there are several reasons why EPA has not mandated 

secondary containment with interstitial monitoring at new petroleum UST 

systems, the most important reason is that it is not believed to be 

necessary to protect human health and the environment at such systems 

(in contrast to hazardous substance UST systems, discussed in section 

III.C.3. below). The new causes of release information (discussed 

previously in today's preamble) shows that the use of new, protected, 

single-walled USTs has, so far, resulted in the virtual disappearance of 

failures, because these new USTs have preventive controls for the main 

cause of past tank failures: corrosion of unprotected, bare steel. This 

new information also revealed that protected UST piping that is 

carefully installed and immediately tested is expected to significantly 

reduce the occurrence of release incidents from this other major 

component of the UST system (a reduction of at least two-thirds 

according to experienced installer estimates). Piping failures will 

not, however, be prevented to the same degree as tank failures.

Thus, the Agency has concluded that petroleum releases will 

be dramatically reduced using protected UST systems. This fact must 

also be considered with the knowledge that numerous effective methods of 

release detection are available and are being used at petroleum UST 

systems nationwide. These methods of detection will enable actions to 

be taken that will minimize the extent of the few releases that do 

occur. Also, the nature of petroleum products and the widely available 

technologies for their clean up provides the means to ensure that 

adverse impacts from such releases (when they occur) can be managed and 

remediated.

In consideration of all of the above factors, the Agency has 

concluded that single-walled protected UST systems combined with the 

release detection required today will adequately protect human health 

and the environment. {NOTE: As discussed earlier in this section of 

the preamble, today's final approach to new petroleum UST systems has 

been further tailored to allow infrequent tightness testing of protected 

or upgraded tanks (combined with inventory control) for the first 10 

years of their operating life, with more release monitoring required of 

the UST system piping--including continuous monitoring of pressurized 

lines.}
b. Option 2: Secondary Containment With Interstitial Monitoring

Several commenters supported the use of secondary containment 

with interstitial monitoring for various reasons, including: product 

releases would be completely contained and prevented from adversely 

impacting the environment and public health; it is a more rapid and 

reliable form of release detection; the cost is comparable to singlewalled UST systems with release detection; and the need for conducting 

site assessments and corrective action would be avoided. Others, 

however, opposed its required use with new petroleum tanks for reasons 

such as: the greater capital and installation costs do not justify the 

environmental gains that would be achieved (in comparison to the singlewalled approach); and this approach is not compatible with current 

trends in industry that are well underway in upgrading existing UST 

systems.

As previously stated, EPA agrees that secondary containment 

with interstitial monitoring would most likely result in fewer releases 

to the environment compared to protected single-walled UST systems with 

release detection. UST systems having secondary containment and 

interstitial monitoring are not perfect, however, and failures of these 

systems will also occur and result in some releases into the environment 

that will have to be remediated. Although protected single-walled 

systems would result in more releases, the Agency has concluded that 

this increase is not a significant added threat to human health and the 

environment given that release detection will minimize the extent of 

these additional releases, and the availability of petroleum cleanup 

technologies is widespread and capable of alleviating any resultant 

adverse impacts. In addition, the Agency is concerned that many owners 

and operators would delay upgrading their existing petroleum UST systems 

to the extent allowed by law or even to the point of noncompliance, 

because of the perception on the part of many commenters of the 

significance of higher capital and installation costs that would result 

from requiring secondary containment and interstitial monitoring 

(compared to protected single-walled USTs with release monitoring).

c. Option 3: Classification Approach

EPA recognized from the outset that releases from petroleum 

UST systems located in certain sensitive areas pose a greater risk of 

harming human health and the environment than others. As a consequence, 

one of the regulatory options the Agency considered extensively in 

developing the final rule was a federal classification approach based 

upon the potential impact of a release. Under this approach, a class or 

classes of UST systems located in high-risk areas would be subject to 

more protective requirements than UST systems located in less sensitive 

areas.

Although the proposed baseline standards for prevention and 

detection of releases made no differentiation based on class, the Agency 

requested comment in the April 17 proposal on the general desirability 

and feasibility of a classification approach to regulating UST systems. 

EPA also sought comment on a specific, two-tiered classification 
scheme. Under this scheme, owners and operators of UST systems located 

in high-risk areas, defined as the area within a specified distance of a 

public drinking-water well, would be required to use secondary 

containment. The baseline standard of protected, single-walled tanks 

with release detection would be allowed in low-risk areas.

EPA received several comments that favored or opposed 

inclusion of a federal classification approach in the final rule. 

Several commenters in favor of a class approach suggested, and the 

Agency has considered since proposal, alternative regulatory schemes 

with respect to how requirements should differ among UST systems in 

different classes. The schemes examined included accelerating the 

schedule for upgrading of existing UST systems to new tank standards or 

for compliance of existing UST systems with release detection 

requirements in high-risk areas; imposing more stringent design 

requirements (e.g., secondary containment) in high-risk areas; and 

imposing more stringent design requirements in all areas except those 

designated as low risk by the implementing agency. The Agency also 

explored several potential criteria proposed by commenters for 

differentiating among classes. Hydrogeologic criteria, such as 

proximity to ground water used for drinking water, were considered most 

extensively. The criterion EPA selected for detailed analysis was 

distance to a public water well. (For discussion of the results of the 

analysis see the Regulatory Impact Analysis for the Technical 

Regulations.)

As pointed out by several commenters, the concept of a 

classification approach to regulating UST systems is appealing for many 

reasons. Because the potential impact of a release is greater in more 

sensitive areas, a classification approach tailors the level of 

protection to the risk posed in a particular area. EPA's analyses of 

various classification schemes indicated that, without considering the 

costs of implementation, the benefits of a classification approach, 

primarily in terms of corrective action costs avoided, could be 

significant. Cleanup of contamination is especially difficult and 

expensive in sensitive areas, such as where ground water used for 

drinking water is affected. Classification could also provide a 

priority-setting scheme for enforcement and corrective action.

Despite the advantages, EPA has not included a classification 

approach in the final rule. Commenters' arguments against a federal 

classification approach influenced the Agency's decision. EPA agrees 

with commenters that the baseline requirements set by the final rule 

will adequately protect the environment in all areas while also 

encouraging timely voluntary compliance by avoiding unnecessary 

additional complexity and providing reasonable flexibility for UST 

system owners and operators. Although EPA supports the concept of 

differential protection based on the potential impact of a release, the 

Agency believes that, for this program, classification at the federal 

level is neither feasible nor practical. EPA is particularly concerned 

about the potential hindrance to state program approval and the 

difficulties of implementing a classification approach at the federal 

level.
Due to the size and nature of the community to be regulated, 

the success of this program depends largely upon implementation at the 

state and local levels. Most states, however, have not developed 

classification systems. Development of appropriate and workable 

classification schemes could take significant time and resources given 

the number of environmental and other factors that must be considered. 

The Agency is concerned that the steps necessary to define criteria and 

then identify high-risk and low-risk areas in states that have not yet 

done so could delay implementation of the program and divert scarce 

resources from efforts to achieve the improvements of the baseline UST 

regulatory requirements, which will provide most of the benefits. This 

additional complication may discourage states from seeking approval 

altogether. The Agency has concluded that the potential reluctance of 

states to implement this program as a consequence of requiring a 

classification approach could result in less successful protection of 

the environment and human health.

In addition, even without implementation delays, a federal 

classification scheme is not likely to provide significant real 

additional protection. Several commenters stated (and the Agency has 

concluded) that, at the federal level, any criteria used to classify 

would have to be simple (such as specified distance to a water well) 

because implementation of a classification scheme based on more complex 

criteria would not be feasible. Yet, given the diverse hydrogeologic 

conditions that exist in the United States, no single, simple 

classification criterion would be appropriate everywhere. For example, 

a distance to drinking-water well criterion, as presented in the 

preamble to the proposal, is meaningless in locations such as Phoenix, 

Arizona, where the depth to ground water is so great that releases from 

UST systems will rarely contaminate drinking-water wells; or in places 

like Dade County, Florida, where ground water may move so fast that a 

release could travel the standard distance within a short period of 

time. Because defining and identifying high-risk areas is so highly 

dependent on local (site-specific) hydrogeologic and other factors, EPA 

believes that state and local implementing agencies can make the most 

meaningful determinations of classes.

Although the Agency has concluded that a classification 

approach at the federal level is neither feasible nor desirable, EPA 

believes that a classification approach to regulating UST systems at the 

state or local levels, where local environmental conditions are better 

known, may be both feasible and appropriate. Under today's approach, 

the Agency allows but does not require states to use a classification 

approach if it is appropriate for the conditions in the state. For 

example, states that have already developed a classification scheme may 

decide to use it to regulate USTs. For such states, the potential 

difficulties associated with implementing a classification approach to 

regulating UST systems may be significantly reduced.
2. Existing UST Systems Containing Petroleum

a. Mandatory Upgrading or Replacement of Substandard UST Systems

In the preamble to the proposal, the Agency identified four 

regulatory approaches to scheduling the upgrade or replacement of 

substandard existing UST systems: (1) rapid upgrade or replacement 

(within 3 to 5 years of final rule promulgation), (2) gradual upgrade or 

replacement (within 6 to 12 years of final rule promulgation), (3) no 

required upgrade or replacement, and (4) scheduling of 

upgrade/replacement based on a class approach (upgrade or replace tanks 

located in environmentally vulnerable areas first). EPA proposed to 

implement scheduling of mandatory upgrade/replacement using the gradual 

approach (within 10 years after the effective date of the final rule) 

and has retained this requirement in today's final rule.

Many commenters supported the proposed 10-year compliance 

period for the reasons identified in the preamble to the proposal (52 FR 

12676). However, some recommended a shorter time period, stating their 

belief that industry resources could meet the demand and that a faster 

upgrading schedule would prevent a significant number of future product 

releases. In contrast, other commenters suggested a longer compliance 

period than proposed and argued that more time was needed to become 

familiar with the UST regulations, that owners of multiple tank systems 

would not be able to finance upgrades/replacements in 10 years or less, 

and that the service industry would need more time to implement upgrades 

for this large universe of existing tank systems.

As stated in the proposal, the Agency agrees that if 

upgrading could be completed in the shorter compliance period (3 to 5 

years) it would decrease the number of product releases and thereby 

provide greater protection of human health and the environment. 

However, the Agency also agrees with those commenters who believe that 

the large number of existing UST systems essentially precludes industry 

from implementing upgrade requirements faster than the proposed 10-year 

period. Furthermore, EPA is in agreement with many of these same 

industry commenters who indicated that a 10-year compliance period is a 

reasonable time period and would not be overly burdensome. EPA is aware 

of numerous industry upgrading programs that have already started and 

will be completed within this time frame.

EPA continues to believe that the alternative of not 

requiring upgrade/replacement of substandard systems is simply 

unacceptable because the Agency has concluded that UST owners probably 

would not upgrade if it is not required. The universe of 1.4 to 2 

million UST systems largely consists of unprotected, bare steel tanks. 

The new causes of release information summarized previously in this 

preamble (and derived from the "Causes of Release from UST Systems" 

report) confirms that the unprotected segment of the UST universe is 

very likely to leak due to corrosion and piping failures and, therefore, 

presents a significant threat to the public health and environment. 

Historical tank replacement rates, established trends in the closure of 

existing retail motor fuel businesses over time, and the imposition of 
this new regulatory program are expected together to result in rapid 

decrease in these substandard UST systems nationwide. However, a 

totally voluntary program of UST system upgrading is not expected by EPA 

to result in the timely upgrade or replacement of UST systems on a 

nationwide basis, particularly given the large number and heterogeneous 

nature of this universe of existing UST systems. In order to ensure 

human health and the environment are protected, the Agency has 

established a clear national goal of upgrading all substandard UST 

systems within 10 years that rejects a purely voluntary approach as 

inadequate. This goal is intended to prompt all UST owners and 

operators to plan for and undertake the upgrading steps that are needed 

to protect human health and the environment.

Another option considered by the Agency in development of the 

proposal was to further require upgrade and replacement based on the use 

of a class approach that scheduled more rapid UST system 

upgrades/replacements in the most vulnerable areas (e.g., ecologically 

sensitive sites or sites in close proximity to drinking water sources) 

while allowing other UST systems to be phased in on a more gradual 

basis. Many commenters recommended staggering the implementation 

schedule for upgrade/replacement based on other factors (besides class) 

such as tank age, tank size and type, proximity to human populations, 

and the measured corrosivity of a site. The common concern among these 

commenters was that a staggered schedule would prevent all owners from 

being allowed to wait until the last minute to bring their existing 

substandard tank systems into compliance and would, thereby, ensure a 

more even, implementable, and serviceable demand for tank 

upgrade/replacement over the 10-year period.

The Agency has decided not to require the phase-in of 

upgrading based on the class approach strategy, or on the basis of any 

other factor, for several reasons. Although many factors on which to 

base tank upgrade/replacement have been identified, because of the 

serious ramifications to the owner and operator associated with the 

technical requirements for upgrading, EPA believes no single risk-based 

factor is appropriate or applicable to mandate nationwide for all 

existing UST systems. Today's general 10-year requirement in the final 

rule also allows implementing agencies in approved states, or under 

State law, the opportunity to decide the staggered schedule on which 

upgrades should be conducted and what factor(s) are most applicable to 

their tank population. Regardless of what type of state action is 

taken, upgrading is already rapidly taking place through numerous 

industry programs. Today's final approach allows them to continue to 

use the numerous different phase-in approaches that are already 

successfully underway. EPA believes this flexibility should also 

encourage others to upgrade because they can set their own schedules to 

meet the 10-year deadline. Thus, EPA has concluded that much of this 

regulated community will have completed these voluntary programs of 

closure and upgrading within the mandated 10-year period, and, 

therefore, the number of existing USTs that otherwise will have to be 

upgraded by the end of this upgrading period is expected to be 

relatively small. The implementation of today's final requirements for 

release detection (and the financial responsibility requirements to be 

provided later) are also expected to prompt rapid upgrading and should 
work to ensure that the implementation difficulties at the end of the 

10-year period that were cited by some commenters are not encountered 

due to a backlog of upgrading demand.

In summary, EPA believes that the 10-year upgrade requirement 

will not present an undue burden on industry and is implementable, but 

is needed to prompt a significant portion of this regulated community 

into making the upgrades and improvements necessary to protect human 

health and the environment. It will also provide industry and the 

states with some flexibility that will allow (and thereby encourage) 

them to determine their own approaches and schedules for ensuring tank 

upgrade/replacement programs are implemented expeditiously within the 

nationally mandated timeframe.

b. Methods of Release Detection

The majority of existing UST systems are not currently being 

monitored for releases to the environment. Therefore, EPA continues to 

believe that a fundamental goal of today's regulatory approach must 

include the establishment of reliable release detection at all UST 

systems. In the proposal (52 FR 12676), the Agency required all 

existing substandard UST systems to comply with one of the six release 

detection methods proposed for new USTs (52 FR 12713). The dual 

objective of this proposed approach was to allow for the continued 

development of release detection technologies and also to ensure that 

only sound and reliable release detection methods were used. 

Particularly for petroleum UST systems, the Agency believed many 

releases would be detected if an appropriate method was selected and 

properly used.

In the preamble to the proposal (52 FR 12676), EPA identified 

that a wide variety of release detection methods (applied either 

internally or externally to the tank) were currently on the market but 

with limited data available concerning their performance. This lack of 

performance data and field experience was corroborated by many 

commenters. Although numerous comments were received regarding the 

release detection methods proposed (see section IV.D. of today's 

preamble for a summary and discussion of these comments), the Agency did 

not receive any comments that opposed the general approach of mandating 

the use of at least one of the allowed methods at existing UST systems. 

Other commenters noted their successful use of different types of 

methods.

Performance data obtained from commenters and from EPAsponsored research since proposal support the Agency's decision to 

retain the proposed approach in the final rule. (EPA solicited public 

comment concerning this new information on March 31, 1988; 52 FR 10403.) 

The Agency is convinced that the proposed release detection methods, 

when properly applied and performed as specified in the final rule, will 

successfully detect the large number of leaks believed to already have 

occurred. For example, over the past year in California and Florida, 

several thousand UST system releases have been identified using these 

methods of release detection, and there appear to be few instances where 
releases have been later discovered through other means (e.g., off-site 

impacts) when release detection was being properly conducted at a site.

3. Hazardous Substance UST Systems

UST systems containing hazardous substances were proposed to 

have secondary containment with interstitial monitoring unless the owner 

or operator obtained a variance by demonstrating that another release 

detection method would be effective in detecting releases of that 

substance from a single-walled UST (see 52 FR 12677, April 17, 1987). 

The reasons for selecting this proposed approach were: (1) information 

is not available on the applicability and demonstrated reliability of 

release detection methods at most hazardous substance USTs, and (2) few 

industry and state and local agency UST programs yet apply to hazardous 

substance USTs and, thus, there is little collective experience on 

management of such USTs. The Agency recognized that some release 

detection methods for petroleum UST systems might also perform well at 

some hazardous substance USTs. Hazardous substance USTs, however, store 

an array of individual chemical compounds that vary widely in their 

physical and chemical characteristics and that may not be readily or 

reliably detected using release detection methods developed for singlewalled UST systems storing petroleum products. They also may not be 

able to be as readily addressed by corrective action technologies that 

are already widely available for petroleum releases. Therefore, the 

proposed approach required secondary containment at all new hazardous 

substance UST systems, unless owners and operators could demonstrate 

that an alternative release detection method could be reliably applied 

and operated.

Several commenters were opposed to the proposed secondary 

containment approach at new hazardous substances UST systems because: 

(1) they do not believe that chemicals designated as hazardous 

substances are any more hazardous than petroleum products (and, 

therefore, should not have to meet more stringent requirements), and (2) 

EPA has not provided a technically valid explanation of why singlewalled USTs are appropriate for petroleum products but not for hazardous 

substances. It was also suggested that, instead of having a lengthy and 

costly variance procedure on a case-by-case basis, the Agency should 

incorporate a variance in the final rule for certain classes of 

hazardous substances.

The Agency has decided to retain secondary containment for 

all new hazardous substance USTs in today's final rule because EPA has 

not received any additional information or data since proposal to 

convince the Agency that reliable and appropriate release detection 

methods are generally available for hazardous substance USTs. The 

Agency continues to believe that under certain conditions, hazardous 

substances will pose a greater risk to human health or the environment 

than petroleum products. Furthermore, there are proven, reliable and 

available release detection methods and cleanup technologies for 

petroleum, whereas the applications of these same release detection 

methods and cleanup technologies are neither proven nor available for 

hazardous substances.
Also retained in the final rule is the proposed exception for 

those owners and operators who, by means of a variance, can demonstrate 

that a release detection method (other than interstitial monitoring) can 

be successfully installed and operated at a specific hazardous substance 

UST system to detect releases of the stored substance. An additional 

requirement in the final rule is that an owner and operator must also 

demonstrate that a corrective action method is available to clean up the 

release. The Agency decided not to structure the variance procedure by 

classes of hazardous substances because physical properties of chemicals 

within a class can be quite variable (for example, wide ranges in 

solubility and volatility) and require different corrective action 

approaches, and one release detection method would not reliably detect 

all of the chemicals within that class. (A more detailed discussion on 

the final rule regarding hazardous substance USTs is presented in 

section IV.D. of today's preamble.)

A detailed discussion of the methods of release detection 

allowed for existing petroleum UST systems is also presented in section 

IV.D. of today's preamble.

4. Corrective Action

An important facet of today's final strategy for regulating 

underground storage tanks is to ensure that public and private drinking 

water supplies are protected, and that necessary steps are taken to 

abate other health and safety threats (such as fires and explosions) due 

to present and future releases from UST systems. As described 

previously in this preamble, tens of thousands of UST systems are 

believed to have already leaked substantial quantities of regulated 

substances into the environment and numerous public and private wells 

have already been threatened or destroyed. As discussed in the preamble 

to the proposal (52 FR 12678), the development of a regulatory program 

for corrective action started with three assumptions: (1) the need to 

implement the requirements through the extensive participation of state 

and local UST programs; (2) the approach taken must be able to work as 

the nature of the UST corrective action problem changes over time; and 

(3) a process must be set up that ensures owners and operators get 

quickly to the task of cleaning up all releases, although the completion 

of corrective action may take a long period of time at any one site.

The proposal provided for separate but very similar 

corrective action processes for UST systems that contain petroleum and 

those that contain hazardous substances. In the proposal, the Agency 

solicited comment on whether the proposed requirements should be 

integrated into one subpart. The proposal also divided the regulatory 

requirements for corrective action into two stages: (1) immediate 

abatement actions that all owners and operators must take in response to 

a release; and (2) long-term investigation and remedial action measures 

that may be taken on a site-specific basis to protect human health and 

the environment. The Agency solicited public comment on the approach 

taken to these immediate abatement (Stage I), and long-term remedial 

action (Stage II) issues in the proposal. These and numerous other 
corrective action issues are discussed in more detail in the following 

section of this preamble that addresses the section-by-section analysis 

of the final corrective action rules (see section IV.F.). The following 

discussion briefly highlights the major decisions and influences 

(including public comment) that went into the development of the 

Agency's final approach to corrective action for UST systems storing 

regulated substances.
a. Corrective Action for Regulated Substances

The proposal provided separate corrective action processes 

for UST systems storing petroleum and those storing hazardous substances 

(proposed Subparts F and G). The stated purposes of this approach were: 

(1) to avoid confusion over which procedures must be followed at a 

release site; and (2) to construct an approach towards hazardous 

substances corrective action that was very similar to the one for 

petroleum, except that it was intended to move the owners and operators 

more quickly to collect, array, and assess the information needed to 

determine the nature, extent, and hazard of the corrective action 

release (52 FR 12682). The dividing line between Stage I and Stage II 

of the process was intended to occur earlier in the response to a 

hazardous substance release, thus following more closely the RCRA 

Subtitle C hazardous waste tank approach to corrective action. This 

proposed approach was an attempt to provide a response process for 

hazardous substances that recognized the relatively greater hazards that 

could be posed by hazardous substances releases, and that ensured that 

there was consistency with the corrective action approach required for 

hazardous waste tanks. EPA solicited comments on whether the petroleum 

and hazardous substance requirements for corrective action should be 

merged in the final rule.

In response to public comments received, and several other 

revisions made in the final corrective action rules, the Agency has 

decided to consolidate the requirements for UST corrective action into 

Subpart F for all regulated substances (both petroleum and hazardous 

substances) for the reasons discussed below. All of the comments 

received by EPA concerning the merging of the two proposed subparts were 

in favor of it, although they made different suggestions on how to 

accomplish this consolidation (discussed in more detail later in the 

section-by-section analysis of this preamble).

Although the preamble to the proposal described the Agency's 

intention to foster quicker investigatory and cleanup actions at 

hazardous substances release sites, as was pointed out by some 

commenters, the few differences in the actual regulatory language 

between the two separate subparts was not likely to attain this end. In 

fact, most of the requirements within the two proposed subparts were the 

same. The most significant differences were that a free product 

investigation was not a required step for hazardous substance responses, 

and a more rapid (within 30 days) and detailed reporting of certain 

information was required by owners and operators with hazardous 

substance releases (see proposed § 280.74(b)) than for those with 

petroleum releases. Prompted by these public comments, additional 

review of these proposed differences has led the Agency to agree that 

they do not necessarily lead to faster corrective actions at hazardous 

substance release sites. Furthermore, even if this end was achieved 

somewhat for hazardous substance releases, the Agency does not believe 

it would protect human health and the environment to move less quickly 

towards the remedial actions required with petroleum releases. Thus, in 

the merger of the two subparts in today's final rules, the Agency has 

developed a process that ensures the most rapid reporting, 

investigation, and corrective action at all UST release sites that is 
believed to be attainable (the details of today's consolidation are 

discussed in more detail later in section IV.F. of today's preamble).

Because the requirements of the two proposed subparts were 

largely the same, EPA also believes that today's merger of them into one 

consolidated Subpart F for all regulated substances avoids a significant 

source of potential confusion within the regulated community. Despite 

the slight procedural differences between the two subparts, the Agency 

is now convinced that the work involved in investigating petroleum and 

hazardous substance releases will be very similar. Also, given that the 

similarities in the characteristics of different petroleum products are 

expected to lead to more rapid and widespread understanding of how to 

respond routinely to petroleum releases (mostly gasoline), the actual 

investigation, initial abatement of hazards, and the availability of 

corrective action technology for petroleum releases may result in more 

rapid and effective release responses at sites with petroleum releases 

than those with a hazardous substance release. 

The Agency continues to believe that under certain 

conditions, hazardous substance releases can pose a greater hazard to 

human health and the environment than petroleum releases. However, the 

consolidated requirements in today's final rules have been designed to 

allow the implementing agency to cause the owner and operator to move as 

rapidly as is necessary to identify and control any such additional 

potential threats. For example, under the final rules, the 

identification and recovery of free product now must be considered at 

both petroleum and hazardous substance release sites. This required 

consideration of free product recovery, however, does not hinder the 

progress of corrective action at sites with releases of hazardous 

substances because the presence and recovery of free product is already 

something that must be commonly considered at all release sites (whether 

petroleum or hazardous substances). The final rule allows enough 

flexibility to ensure that this type of action is tailored, under the 

direction of the implementing agency, to site conditions and the type of 

substance released.

b. Stage I: Investigation of Releases and Immediate Corrective Action

EPA proposed requirements for the first stage of the 

corrective action process (Stage I) by establishing immediate steps that 

must be taken to abate imminent health and safety hazards whenever a 

release is confirmed. The basic approach assured that the following 

activities were undertaken by the owner and operator at all sites with a 

confirmed release: (1) immediate notification of the implementing 

agency; (2) actions needed to stop further releases; (3) mitigation of 

safety hazards due to fire and explosion; (4) removal of contaminated 

soils; (5) investigation of the existence and extent of floating free 

product; and (6) initiation of the removal of free product and submittal 

of free product recovery plan unless directed to do otherwise by the 

implementing agency.

Numerous public comments on issues related to these proposed 

requirements are discussed in more detail later in this preamble. In 

general, many commenters believed the proposal was unclear as to what 
exactly had to be done, and by whom, to comply with the requirements. 

EPA, in response to these commenters, has revised the language in the 

final rule to clarify which elements of the initial response actions are 

mandatory and which are discretionary. The mandatory requirements are 

intended to ensure three goals are accomplished:

oTo bring leaking UST sites under control with respect to 

immediate health and safety hazards;

oTo stabilize the site so that contamination will not worsen as 

investigation and potentially long-term remedial actions are 

considered; and

oTo be self-implementing in that these measures emphasize the 

responsibility of the owner and operator to take immediate 

action without awaiting approval of the implementing agency.

All sites with releases of regulated substances must 

investigate the area around the UST system to be able to characterize 

the size and nature of the release (e.g., a small spill or a large, 

continuing slow release). The findings of this initial investigation 

must be reported to the implementing agency, which has the discretion to 

require a more extensive site characterization based on these initial 

findings. The proposal has also been revised to make this more 

extensive examination of ground-water and soil contamination mandatory 

when the initial investigation reveals that a significant release has 

occurred (e.g., free product floating on the ground water or saturated 

soils in the subsurface), even in the absence of direction from the 

implementing agency. Thus, today's final rule requires all releases 

that seriously threaten or impact ground water to be automatically 

investigated by the owner and operator to characterize the extent of 

ground-water contamination and any soil contamination remaining at the 

site.

c. Stage II: Long-Term Corrective Action Options

EPA also proposed requirements for the second stage of the 

corrective action process (Stage II) addressing long-term remediation of 

contaminated soils and ground water. The Agency solicited public 

comment on three regulatory options for establishing long-term cleanup 

requirements: (1) national cleanup standards, with a variance provision; 

(2) site-specific standards to match the risk presented; and (3) a 

predetermined class approach. The proposal emphasized the second 

approach, with its site-specific cleanup targets based on (1) the data 

from the detailed site investigation of soil and ground-water 

contamination performed by the owner and operator and (2) the sitespecific risk present as determined by the implementing agency using 

exposure and risk assessment techniques.

EPA received public comments for and against each of the 

three options for establishing cleanup levels. The majority of 

commenters preferred the proposed site-specific approach as the best way 

to accommodate the diversity of UST releases nationwide. Those in favor 

of establishing national cleanup standards in the regulations expressed 
the opinion that this would expedite cleanups and provide greater 

national consistency in cleanup results. Supporters of the class 

approach cited the wisdom of tailoring cleanup efforts to a 

predetermined assessment of risk based on prospective classifications 

tied to ground-water vulnerability. EPA has decided to retain the sitespecific approach in the final rules.

For the same reasons that were cited in the preamble to the 

proposal (52 FR 12680-12682) and supported by most commenters, EPA 

continues to believe that the site-specific approach is the most 

appropriate because it allows implementing agencies the necessary 

flexibility to address corrective action based on the unique 

circumstances of the site. It also enables state and local governments 

to build upon their own experiences when assessing the need for and 

extent of corrective action. EPA is not convinced that a national 

standards approach will result in more rapid and consistent levels of 

corrective action. No data were provided that demonstrate this 

position. In fact, the information available to the Agency about UST 

cleanup technologies indicates that the level of actual cleanup achieved 

is much more dependent on the limitations associated with current 

corrective action equipment and the problems posed by individual site 

conditions, than it is on the cleanup levels established in a corrective 

action plan (or by regulation). In selecting the site-specific 

approach, the Agency notes that it does not preclude the use of the 

other two approaches by implementing agencies. Some states already are 

using a statewide standards approach.

The Agency continues to believe that the site-specific risk 

assessment process can be streamlined to ensure that the corrective 

action needed at a site can be identified rapidly and initiated quickly. 

EPA maintains the position expressed in the proposal's preamble (52 FR 

12681) that site-specific cleanup levels will have to account for 

potential exposure of the public to contamination at the site. If a 

drinking water supply, public or private, is affected or threatened by 

the release, then the cleanup levels in the corrective action plan 

should be established using health-based levels as the target for 

cleanup of the release, unless an alternative source of drinking water 

can be provided to the potentially affected public. The Agency is 

developing further guidance concerning the use of risk assessment and 

exposure assessment techniques for releases at UST sites. These efforts 

are expected to further streamline the site-specific approach to 

regulation promulgated today. (Further discussions of the site-specific 

approach to standard setting and corrective action plans are provided 

later in the section-by-section analysis in section IV.F. of today's 

preamble.)

IV. ANALYSIS OF TODAY'S RULE

A. Program Scope
1. Applicability

As described previously, this rule generally applies to all 

owners and operators of UST systems containing regulated substances. 

Regulated substances consist of either petroleum or any substance 

defined in section 101(14) of CERCLA (but not including any substance 

regulated as a hazardous waste under Subtitle C). The following 

sections discuss the tank systems subject to exclusions from today's 

requirements and the deferral of regulation for other UST systems.

2. Regulatory Exclusions

The regulatory exclusions in today's final rule are based on 

a number of statutory provisions and regulatory considerations. Section 

9003(a) of RCRA requires the Administrator to establish an UST program 

"as may be necessary to protect human health and the environment." In 

addition, Section 9003(b) allows the administrator to consider such 

factors as tank size and quantity of substances stored when establishing 

necessary requirements. The Agency believes that this statutory 

language allows some flexibility for EPA to concentrate its resources on 

tanks that pose the greatest potential environmental threat. Section 

9001 defines the universe of the UST program and indicates that EPA 

should regulate tanks containing an "accumulation" of regulated 

substances. Section 9001 also excludes tanks regulated under Subtitle C 

from the jurisdiction of Subtitle I. Finally, section 1006 of RCRA 

generally requires integration of RCRA with the Federal Water Pollution 

Control Act; the Safe Drinking Water Act; the Marine Protection, 

Research, and Sanctuaries Act; and the Atomic Energy Act.

Based on these provisions, the Agency is today excluding from 

regulation several types of tank systems. These exclusions will 

decrease the regulatory burden on implementing agencies so they can 

focus their resources on types and classes of tanks that pose a 

significant threat to human health or the environment. Unlike statutory 

exclusions, regulatory exclusions may be modified by the Agency in the 

future should new information show that regulation of such an excluded 

tank type is necessary.

Four classes of tanks are excluded from regulation in the 

final rule: UST systems containing mixtures of hazardous waste and 

regulated substances; equipment and machinery that contain regulated 

substances for operational purposes; wastewater treatment tanks 

regulated under the Clean Water Act; and UST systems excluded via one of 

three de minimus exclusions. A specific regulatory exclusion for UST 

systems containing mixtures of hazardous waste and regulated substances

was included in the proposed rule (52 FR 12687). The preamble of the 

proposal also discussed de minimus exclusions. The other two regulatory 

exclusions were regulatory deferrals in the proposal. The rationale for 

these exclusions is discussed below.
a. Tanks Regulated Under Subtitle C of RCRA

Because USTs containing a mixture of hazardous wastes 

(regulated under Subtitle C of RCRA) and regulated substances (regulated 

under Subtitle I) are subject to dual jurisdiction from Subtitle C and 

Subtitle I, EPA is today excluding these tanks from Subtitle I 

regulation. As evidenced by the exclusion of substances covered under 

Subtitle C within the statutory definition of "regulated substance," the 

Agency believes that this exemption is consistent with Congressional 

intent not to have redundant requirements under these two programs. 

Because of the continued coverage of these tanks by Subtitle C, the 

exclusion of these tanks from Subtitle I regulations will not present a 

risk to human health and the environment, and, thus, Subtitle I 

regulation is not "necessary to protect human health and the 

environment." 

Several commenters pointed out that in the proposed rule this 

exclusion applied only to mixtures of hazardous wastes and hazardous 

substances. This wording would subject tanks that contain mixtures of 

hazardous wastes and petroleum to regulation under both Subtitle C and 

Subtitle I. The commenters requested that the wording be changed so 

that all mixtures with hazardous wastes regulated under Subtitle C would 

be excluded from these regulations.

The original wording in the proposal was based upon the 

statutory jurisdiction of the program. Under section 9001(2)(A), the 

exclusion of tanks regulated under Subtitle C pertains only to tanks 

containing hazardous substances, not to tanks containing petroleum. 

EPA, however, agrees with the commenters that dual regulation of tanks 

containing hazardous wastes and petroleum is not necessary and has 

changed the wording of this exclusion appropriately. This exclusion now 

applies to all tanks subject to regulation under Subtitle C that contain 

mixtures of hazardous wastes and either petroleum or non-petroleum 

regulated substances.

b. Equipment and Machinery that Contain Regulated Substances for 

Operational Purposes

Equipment and machinery that contain regulated substances for 

operational purposes, such as hydraulic lift tanks and electrical 

equipment, are excluded from today's regulations. These specific tank 

categories were deferred from regulation in the proposal, and the Agency 

requested comments on whether, and to what extent, these tanks should be 

subject to regulation under the UST program. Several commenters 

responded to this request and gave several reasons why these tanks 

should not be regulated as USTs. Their comments included three main 

points: the tanks are self-monitoring; the tanks pose a minimal risk to 

human health and the environment; and there have been few leaks.

Because these tanks contain regulated substances solely for 

operational purposes, the commenters argued that the loss of regulated 

substance would be accompanied by faulty operation of the equipment or 

machinery and thus the equipment is "self-monitoring." Second, the 
threat to human health and the environment was judged to be minimal 

because the tanks contain small amounts of regulated substances. Also, 

the commenters said that these devices rarely leak. Data submitted for 

leaks from electrical equipment, for example, show a leak incidence much 

lower than that for other types of tanks such as those at service 

stations.

This category of tanks includes hydraulic lifts and 

electrical equipment. Although commenters did not suggest other 

specific types of tanks that would fall within this class, EPA believes 

that other tanks of this type would also be included, provided that the 

tanks meet two major criteria: the equipment or machinery contains 

small amounts of regulated substances solely for operational purposes; 

and a loss of regulated substance is accompanied by faulty operation of 

the equipment or machinery, such that a loss of fluid causes knowledge 

of the loss.

In excluding this category of tanks, the Agency agrees with 

the commenters that these types of tank systems pose a relatively low 

level of risk compared to other types of storage tanks for the reasons 

given above. Moreover, the Agency recognizes that these tanks, although 

within Subtitle I jurisdiction, are not central to the Congressional 

concerns that created this program. Thus, regulation of these tank 

systems appears at this time to be unnecessary under section 9003(a).

EPA also believes that this potentially overwhelming large 

universe would require considerable effort on the part of implementing 

agencies even for just notification, with very little discernable 

environmental benefit. For example, the universe of hydraulic lift 

tanks alone has been estimated at 350,000 to 600,000 lifts. These 

figures do not include elevator lifts. Regulation of these types of 

tanks would unnecessarily divert implementing agency resources from 

other, more serious health threats. Therefore, today's final rule 

excludes such tanks.

c. Wastewater Treatment Tanks Regulated Under the Clean Water 

Act

The Agency is today excluding all wastewater treatment tanks, 

including any oil-water separators, that are subject to regulation under 

either section 402 or 307(b) of the Clean Water Act (CWA) (33 USC 1151 

and following). These tanks, including tanks at most publicly owned 

treatment works and many private treatment facilities, would otherwise 

be subject to dual regulation. Because these tanks are subject to 

regulation under the CWA, further regulation under Subtitle I is 

unnecessary to protect human health and the environment and would be 

inconsistent with section 1006(b) of RCRA. This exclusion is analogous 

to the "wastewater treatment unit" exclusion under the RCRA Subtitle C 

program (see 40 CFR 260.10, 264.1, and 265.1).

In addition, tanks that treat wastewater or storm water, but 

which are not covered by the applicable sections of the CWA, are being 

deferred from today's final regulations. Such tanks might include many 
oil-water separators found at various facilities. Further discussion of 

these tanks can be found under the deferral section of this preamble.

d. De Minimis Exclusions

Today's final rule has been modified to exclude the following 

tanks: (1) those that have a capacity of less than 110 gallons; (2) 

those holding a very low concentration of regulated substances; and (3) 

those that serve as emergency backup tanks, hold regulated substances 

for only a short period of time, and are expeditiously emptied after 

use.

The statutory definition of tank includes all devices that 

"contain an accumulation of regulated substances." Although legislative 

history provides no guidance on the meaning of the phrase "accumulation 

of regulated substances," the Agency believes the statutory language 

provides some flexibility to define the universe of regulated facilities 

in a manner that focuses regulatory resources on the tanks posing 

substantial risk from storage of regulated substances and, thereby, 

fosters development of a program that most effectively protects human 

health and the environment. Thus, sections 9001 and 9003(a) authorize 

EPA to exclude from its regulations tanks containing de minimis amounts 

of regulated substances. EPA requested comment in the proposed rule 

concerning de minimis exclusion criteria. 

A number of comments addressed the issue of including a de

minimis exclusion in the rule for tanks that hold a small quantity of 

regulated substances. The overwhelming majority of the commenters 

believed that such an exclusion should be part of the final rule. Some 

commenters suggested that a small-capacity exclusion would reduce the 

regulatory burden on the implementing agencies and, thus, result in a 

more effective program. Some commenters believed that a small-capacity 

exclusion was justified because small quantities of regulated substances 

pose less of a health risk than do larger quantities.

In deciding to include a regulatory exclusion for tanks that 

contain small quantities of regulated substances in today's rule, the 

Agency had to balance the benefits and drawbacks of such an exclusion. 

The Agency agrees with the commenters who thought that without an 

exclusion such as this, the regulated universe could be overwhelmingly 

large. Such a large universe would require considerable efforts by the 

implementing authorities even for notification, diverting their 

attention away from other, more potentially environmentally hazardous 

classes of tanks. The Agency agrees that small tanks pose less danger 

to the environment than larger tanks, generally, due to the smaller 

quantity of regulated substances available to leak. In certain cases, 

however, the mismanagement of even small quantities of regulated 

substances could pose serious danger to human health and the 

environment. Nevertheless, the Agency has decided that the detriments 

of attempting to regulate these small tanks greatly outweigh any 

potential benefits from regulation of this class of tank and has, 

therefore, adopted this exclusion.
Several comments were received with suggested sizes for a de

minimis cutoff. These sizes ranged from 100 gallons to 5,000 gallons. 

State and local agencies with de minimis exclusions use cutoffs that 

range from 60 to 2,100 gallons. Because it was apparent that there was 

no standard size for the de minimis exclusion, the Agency chose the size 

limit of 110 gallons capacity. According to one commenter, this size is 

below the smallest petroleum product tank routinely mass produced (275 

gallons), and a 110-gallon level coincides with the Department of 

Transportation definition for minimum portable tank for the 

transportation of hazardous materials. Tanks likely to be exempted 

under this exclusion include many small sumps and other atypical tanks.

The Agency is also today excluding tanks that contain de

minimis concentrations of regulated substances. Because "an 

accumulation of regulated substances" could include within the regulated 

universe USTs holding regulated substances in any amount, no matter how 

small, the regulated universe could include a vast number of tanks that 

contain regulated substances only in small concentrations. These very 

small concentrations could occur accidentally (through contamination) or 

by design (for example, underground tanks storing food that contains a 

preservative that is a regulated substance). The Agency has not 

included a specific percentage threshold as the de minimis cutoff 

because of the many difficulties with measuring tank contents for low 

concentrations. Instead, on a case-by-case basis, the implementing 

agencies will determine if tanks that hold very low concentrations of 

regulated substances are excluded via the de minimis concentration 

rationale. Tanks that are likely to meet this criteria include those 

that are used to treat storm water and municipal wastewater, tanks that 

store potable water that has been treated with chlorine, and in-ground 

swimming pools. EPA believes that such tanks pose a minimal threat to 

human health and the environment, and the inclusion of such tanks in the 

regulated universe would impose an undue burden on the implementing 

agencies because of the potentially large numbers of such tanks. Other 

types of tanks with very low concentrations of regulated substances may 

also be excluded.

The third de minimis exclusion included in today's rule 

pertains to tanks that are emergency spill protection tanks or overflow 

tanks, and are emptied expeditiously following use. This exclusion is 

analogous to the exclusion for emergency response treatment and 

containment under the RCRA Subtitle C program (see 40 CFR 264.1 and 

265.1). Included in this category are many types of sumps and secondary 

barrier tanks. This exclusion does not specify a maximum time a tank 

may hold material, but applies only to tanks that are rarely used and 

are emptied shortly after use. The purpose of this exemption is to 

allow appropriate immediate response to emergency situations. These 

tanks are used for temporary storage of substances in response to a 

leak, spill, or other unplanned occurrences. Regulation of such tanks 

is unnecessary because they are rarely used and expeditiously emptied 

and, therefore, are unlikely to have any long-term leaks. Many of these 

tanks may also be able to be visually inspected because they rarely hold 

regulated substances. Several commenters expressed concern that the way 

the proposed rule was written, the Agency may have been requiring 

infinite layers of secondary containment. For example, in the proposal, 
an UST system was defined to include a secondary containment system, but 

there were references to requiring secondary containment for a hazardous 

substance UST system. Thus, it appeared that secondary containment was 

required to surround secondary containment. By including this exclusion 

in the final rule, the Agency believes that any potential confusion 

regarding the need for secondary barriers (containment) for secondary 

barrier (containment) systems has now been eliminated.

Sumps designed to store petroleum or hazardous substances 

during periodic cleaning or maintenance of machinery or equipment are 

not included in this exclusion. An example of this type of sump is 

turbine oil sumps that are used during maintenance of electric power 

generation turbines.

3. Deferral of Regulations

In the proposal preamble (52 FR 12687), EPA discussed its 

proposed deferral of requirements for the following categories of UST 

systems: wastewater treatment tanks, sumps, systems containing used 

oil, systems containing radioactive waste, systems containing electrical 

equipment, underground bulk storage tanks, and hydraulic lift tanks. 

The Agency requested comments on whether the deferrals were appropriate 

for each category and, if not, what regulations would be necessary.

In today's final rule, the Agency has revised the proposal in 

several ways. As a result of these revisions, tanks in some of these 

categories will fall within the scope of the regulatory exclusions 

described above, some will be subject to full regulation, and some will 

continue to be deferred from regulation. Tanks that are deferred rather 

than excluded are subject to interim UST requirements, but excluded 

tanks are not subject to any regulatory requirements. These revisions 

are briefly summarized below:

oWastewater treatment tanks now fall under two parts of today's 

final rule. Wastewater treatment tanks, including oil-water 

separators, that fall under the jurisdiction of sections 402 

or 307(b) of the CWA are excluded from today's regulatory 

requirements (as discussed above in IV.A.2.). The remaining 

wastewater treatment tanks continue to be deferred from 

Subparts B, C, D, E and G of today's regulations, but are 

subject to interim requirements under Subpart A and 

corrective action under Subpart F.

oMany sumps are excluded from regulation under the CWA-regulated 

wastewater treatment exclusion, and others via one or more of 

the de minimis exclusions; others may be excluded as part of 

the statutory exclusion for storm-water and wastewater 

collection systems. Many of those that are not excluded 

continue to be deferred from Subparts B, C, D, E and G under 

the "field-constructed tank" deferral. Such UST systems are 

subject to the interim prohibition under Subpart A and 

corrective action under Subpart F. Sumps that are neither 
excluded nor deferred from regulation are subject to today's 

regulation.

oField-constructed tanks, which include many tanks classified as 

underground bulk storage tanks in the proposal, are deferred 

from Subparts B, C, D, E and G but are subject to interim 

requirements under Subpart A and corrective action under 

Subpart F.

oUST systems that contain radioactive wastes and other 

radioactive materials have been deferred from Subparts B, C, 

D, E and G but are subject to interim requirements under 

Subpart A and corrective action under Subpart F.

oUST systems containing electrical equipment and hydraulic lift 

tanks, which had been deferred in the proposal, are both 

examples of equipment or machinery using regulated substances 

for operational purposes. As discussed above in IV.A.2., 

both types of tanks have been excluded from regulation under 

Subtitle I.

oTanks containing used oil are no longer deferred but are subject 

to full regulation under today's final rule.

Today's final rule also includes deferral of some subparts of 

the regulations for the following additional categories of tanks:

oAirport hydrant fueling systems and tanks storing diesel fuel 

for emergency power generation at plants regulated by the 

Nuclear Regulatory Commission are deferred from the technical 

standards set forth in Subparts B, C, D, E and G but are 

subject to interim requirements under Subpart A and 

corrective action under Subpart F.

oUST systems that store fuel solely for use by emergency power 

generators are deferred from the release detection 

requirements under Subtitle D. All other regulatory 

requirements apply to these tanks.

EPA's decision making on these various tank types is 

discussed in more detail in the sections below.

a. Wastewater Treatment Tanks

In the proposal, EPA deferred wastewater treatment tanks from 

UST regulation in order to gather more information on the need to 

regulate these tanks and the appropriate type of regulation. EPA 

included oil-water separators (which are considered treatment tanks) 

within the scope of wastewater treatment tanks.

In the proposal preamble, EPA specifically requested comments 

on whether wastewater treatment tanks should be regulated under Subtitle 

I (52 FR 12687). Almost all comments submitted were opposed to 
regulating wastewater treatment tanks under UST regulations. The 

commenters stated that wastewater treatment tanks are process devices 

and flow-through process tanks, not storage tanks; thus, they should not 

be regulated under the UST program. Several commenters also stated that 

wastewater treatment tanks contain large volumes of water and only small 

amounts of oil or hazardous materials and, thus, pose no major threat to 

human health or the environment. It was also stated that wastewater 

treatment tanks that are currently excluded by RCRA are, however,

currently covered by the CWA. They should not, therefore, be regulated 

under UST regulations. In addition, several commenters pointed out that 

if wastewater treatment tanks were to be included in the final rule, 

there is presently no practical method of performing a tightness test on 

these tanks because the tanks are typically open to the atmosphere. 

Inventory reconciliation is not feasible because the very high 

throughput would require more accurate metering than is currently 

available.

EPA does not agree with the commenters who argued that 

wastewater treatment tanks are outside the scope of Subtitle I as "flowthrough process tanks" or part of a storm-water or wastewater collection 

system, which are excluded from the jurisdiction of this program under 

section 9001(1). Wastewater treatment tanks are not part of a 

production process, nor are they part of a collection system. See 

section IV.A.2. for further discussion of the scope of the flow-through 

process tank and storm-water and wastewater collection system 

exclusions. EPA does, however, agree with commenters that the universe 

of treatment tanks could add a large administrative burden that could 

reduce the ability of the implementing agencies to regulate more serious 

threats to the environment.

After review of all available information, EPA now believes 

that wastewater treatment tanks that are currently covered by sections 

402 and 307(b) of the CWA should be excluded from UST regulations as 

discussed in the previous section. In addition, some of these treatment 

devices, such as those treating municipal sewage, typically contain de

minimis concentrations of regulated substances and are therefore 

excluded under today's rule.

Wastewater treatment tanks not covered by the CWA or 

otherwise excluded will continue to be deferred under these regulations. 

Oil-water separators and other similar treatment devices fall under the 

definition of "wastewater treatment tank" under today's rule. The 

deferral for those wastewater treatment tanks not regulated by the CWA 

reflects the Agency's uncertainty regarding the nature of this tank 

population and the appropriateness of some of the UST regulations for 

these tanks. For example, some types of leak detection (such as 

tightness testing) and inventory reconciliation would not appear to 

apply to treatment tanks.
b. Sumps

In the preamble of the proposal (52 FR 12687), the Agency 

requested that commenters submit information on the number, location, 

and substances stored in sumps; how sumps are protected to prevent 

releases from occurring; leak history; and whether the proposed UST 

regulations would be appropriate for sumps. Most of the commenters who 

responded believed that regulations for sumps should continue to be 

deferred because sumps are small, temporary storage facilities that are 

frequently visually monitored and that contain mostly water and only 

small amounts of petroleum or hazardous substances. Also, commenters 

stated that regulation of sumps would pose an unmanageable regulatory 

burden for the implementing agencies and would require an individualized 

approach for each location. Some commenters suggested that de minimis

size, time, and throughput exclusions be developed to prevent sumps from 

becoming subject to the regulations. The only commenters who supported 

regulation of sumps did not believe that Subtitle I was the appropriate 

regulatory authority.

Although commenters did not submit data that would enable EPA 

to determine the total number of sumps nationwide, the Agency realizes 

that that the number of sumps potentially subject to Subtitle I is very 

large and could pose an unmanageable regulatory burden. In addition, 

the Agency agrees with the commenters that many sumps are small, 

temporary storage facilities that contain only small amounts of 

petroleum or hazardous substances. No information was submitted 

concerning whether sumps pose a significant threat to human health or 

the environment.

As discussed above, today's final rule contains de minimis

size, time, and concentration exclusions that are expected to apply to 

many sumps. Also, sumps that are part of a storm-water or wastewater 

collection system are excluded by statute from UST regulations. These 

exclusions will allow the implementing agencies to focus their resources 

on UST systems that are a more significant threat to the environment and 

human health. The Agency believes, however, that large sumps that 

contain significant quantities of regulated substances over a period of 

time do not warrant such exclusion, because they are indistinguishable 

from other regulated tanks. Therefore, factory-built sumps are subject 

to all requirements under today's final rule if they are not subject to 

any other exclusion. Field-constructed tanks, including fieldconstructed sumps, are deferred until information can be obtained on 

what regulations (if any) are appropriate for these systems as discussed 

in the following section. Therefore, the final rule no longer contains 

a deferral for sumps.
c. Field-Constructed Tanks

In the proposal preamble, EPA specifically requested comments 

concerning the applicability of Subtitle I (52 FR 12688) to underground 

bulk storage tanks (UBSTs). In the proposal preamble, EPA considered 

UBSTs as those tanks whose total capacity was 20,000 gallons or greater. 

Several commenters stated their belief that because UBSTs pose a major 

environmental concern and are closely related to other USTs, they should 

be regulated under Subtitle I in the final rule. It was also stated by 

some commenters that secondary containment of UBSTs is feasible and 

other existing leak detection methods are applicable to UBSTs. On the 

other hand, there were some commenters who opposed the inclusion of 

UBSTs in the regulation stating that the differences between UBSTs and 

normal USTs are too great and that many leak detection and leak 

prevention methods are not applicable to UBSTs. There were also 

requests by some commenters that the definition of UBST be clarified and 

included not only in the preamble but also in the final regulation.

After reviewing the comments, EPA has modified the deferral 

of UBSTs to a deferral for tanks that are field-constructed. Although 

many bulk tanks are expected to be deferred because they are fieldconstructed, the capacity of these tanks no longer determines their 

regulatory status.

Field-constructed tanks are usually constructed of steel or 

concrete, shaped like flat vertical cylinders, and have a capacity of 

greater than 50,000 gallons. In contrast, factory-constructed bulk 

tanks are typically long, horizontal cylinders and are less than 12 feet 

in diameter. Tanks that are principally factory-built but are assembled 

in the field are considered factory-built tanks. For example, welding 

two halves of a factory-constructed tank together in the field does not 

qualify the tank as a field-constructed tank.

The deferral of regulation for field-constructed tanks is 

largely based on the fact that design and construction methods for 

field-constructed tanks are different from those for factory-built 

tanks. EPA has not had sufficient time to develop appropriate 

regulations related to design and construction for such tanks.

Comment was divided on the applicability of present leak 

detection and leak prevention methods to bulk tanks. Some commenters 

argued that existing leak detection methods are applicable to UBSTs, 

while others stated that the differences between UBSTs and normal USTs 

are too great to use most presently available leak detection and 

prevention methods for such tanks. EPA believes that the division of 

bulk tanks into field-constructed and factory-built tanks simplifies 

this issue.

EPA believes that because of the different design and 

construction methods used for field-constructed tanks, as well as the 

very large size of some field-constructed tanks, the majority of the 

leak detection methods presently available do not work for such tanks. 

Leak prevention methods may also differ for such tanks. The deferral 
for these tanks is due in part to this restricted availability of 

appropriate leak detection methods.

By contrast, EPA believes that currently available leak 

detection methods are applicable to factory-built tanks. Factory-built 

tanks, even those that are very large, generally conform to standard 

design and construction methods that allow the use of widely available 

leak detection methods.

EPA agrees with commenters that tanks that hold large amounts 

of regulated substances do pose a relatively larger potential danger to 

human health and the environment than other, smaller tanks. However, 

until regulations are developed to govern design and construction of 

field-constructed tanks, they will be deferred.

d. Systems Containing Radioactive Materials

At proposal, the Agency requested comment on the issue of 

whether tanks containing radioactive materials, including high-level 

radioactive waste and tanks containing mixtures of low-level radioactive 

waste and other materials, should meet the proposed standards or whether 

separate standards should be developed. No commenters supported 

regulation of these USTs under Subtitle I. The commenters stated that 

radioactive waste and materials tanks at nuclear facilities are 

regulated by the Nuclear Regulatory Commission (10 CFR 50.34a) and that 

further regulation of these tanks under Subtitle I would be duplicative 

and possibly inconsistent. One commenter noted that these tanks are 

typically made of stainless steel and have a capacity of approximately 

1,000 gallons. The tanks are pressure tested before the nuclear 

facility is licensed to operate and are retested every 10 years. In 

addition, they are constantly monitored for loss of pressure and 

radiation leakage. Commenters also noted that the current Department of 

Energy management program for tanks containing high-level radioactive 

waste is as stringent as, and in some cases exceeds, the proposed UST 

rule.

Because tanks containing radioactive wastes and other 

radioactive materials at nuclear facilities are regulated by the Nuclear 

Regulatory Commission, these tanks could be subject to overlapping 

jurisdiction under Subtitle I and the Atomic Energy Act of 1954 (42 

U.S.C. 2011 and following). The Agency, however, lacks complete 

information on whether these regulations fully cover all appropriate 

areas addressed under Subtitle I. The Agency, therefore, is deferring 

regulation of these tank systems until more information can be gathered.
e. Systems Containing Electrical Equipment

Under the proposed definition of "tank," large numbers of 

utility units in urban and residential areas (e.g., underground 

transmission cables and vaulted transformers for large trunk lines) 

could be subject to regulation. At the time of the proposal, the Agency 

deferred regulation of these structures based on its belief that 

inclusion of these structures in the UST program would be impractical 

and unnecessary. EPA requested that commenters submit information on 

the number, location, and substances stored in these units; how they are 

protected to prevent releases; leak history; and whether the proposed 

regulations would be appropriate for these units.

All of the commenters in this area were opposed to inclusion 

of electrical equipment structures in the UST program. The commenters 

stated that these units are not primarily used for storage and that the 

utilities industry already takes many precautions to prevent releases. 

Dielectric fluids, typically naphthenic mineral oil and synthetic fluids 

such as polybutene or alkylbenzene, are used in underground cable piping 

and vaulted transformers to prevent the cables and transformers from 

overheating. Underground cable piping is cathodically protected and is 

coated to prevent corrosion. The piping is subjected to pressure tests 

both before and after insertion of the cable and addition of the 

dielectric fluid. Electronic monitors at the utility's control center 

indicate potential releases of fluid (i.e., when the required oil 

pressure cannot be supplied by the associated pumping station). In 

addition, transmission line routes are routinely inspected to identify 

potential sources of piping damage, such as the misuse of construction 

equipment. Information submitted by commenters showed that from 1978 to 

1985, utilities nationwide reported an average of less than 1 leak per 

100 circuit miles of cable. In 1985, there were 23 reported leaks 

involving low-pressure systems and 6 reported leaks involving highpressure systems. Of the low pressure system leaks, only one occurred 

belowground.

The Agency believes that there are already strong incentives 

for the utilities industry to prevent releases from underground 

equipment because these leaks could result in system malfunctions and 

widespread power outages. The industry has developed release response 

procedures for notification, containment, and cleanup in the event of a 

release. In addition, despite its widespread use, underground 

electrical equipment appears to pose a minimal threat to the environment 

because of the low leak incidence for such UST systems. Moreover, many 

of these systems also fall within the statutory exclusion for storage 

tanks situated on or above the floor of underground areas, such as 

basements and cellars. Therefore, to allow the implementing agencies to 

focus their limited resources on more significant potential threats, the 

Agency has decided to exclude underground electrical equipment from the 

final rule as equipment and machinery that contain regulated substances 

solely for operational purposes.
f. Hydraulic Lift Tanks

In the proposal preamble, EPA deferred the application of the 

proposed technical standards to hydraulic lift tanks; however, these 

tanks would have been subject to Subparts F and G of the proposed rule 

(i.e., corrective action). "Hydraulic lift tanks" are those tanks used 

to store fluid used in hydraulic lifts at service stations and similar 

devices such as lubrication oil reservoirs for elevators. After review 

of all available information, EPA has now decided that, like the 

electrical equipment tanks discussed above, hydraulic lift tanks will be 

excluded in the final rule as equipment or machinery that contain 

regulated substances solely for operational purposes.

In the proposal preamble, EPA specifically requested comments 

on whether hydraulic lift tanks should be regulated, and if regulated, 

to what extent (52 FR 12689). In response, several commenters stated 

that hydraulic lift tanks should not be regulated under the final rule 

because they are not used for storage and many of them are almost 

completely aboveground. It was suggested by several other commenters 

that hydraulic lift tanks not be regulated because they pose either 

minimal or no threat to human health or the environment and are selfmonitoring. If problems do arise, the lifts cease to operate when they 

lose fluid. It was also mentioned by several commenters that due to the 

location of hydraulic lift tanks (e.g., under buildings), the cost 

impact involved in bringing these tanks under regulation would be 

substantial. Finally, several commenters stated that the inclusion of 

hydraulic lift tanks in the regulation would cause severe impacts on the 

implementing agency; the number of hydraulic lifts has been estimated at 

over 800,000. Several commenters suggested, however, that special 

standards be developed specifically for hydraulic lift tanks. It was 

also suggested that only those hydraulic lift tanks that exceed 100 

gallons be regulated under the final rule.

EPA deferred regulation of hydraulic lift tanks at proposal 

to allow time to gather additional information on the subject. In the 

preamble to the proposal, however, EPA identified several reasons why, 

based on preliminary information, the Agency felt that regulation of 

such tanks would be unnecessary. After reviewing all comments 

submitted, EPA believes that it is appropriate to exclude all hydraulic 

lift tanks from regulation. EPA agrees with those commenters who stated 

that hydraulic lift tanks pose a minimal threat to the environment and 

are self-monitoring. The Agency is today excluding these types of tanks 

as equipment that contains regulated substances solely for operational 

purposes (see section IV.A.2.b. above).
g. Used Oil USTs

The Agency proposed to defer regulation of used oil USTs. 

The Agency indicated, however, that it might apply the proposed 

technical standards to used oil USTs in the final rule following public 

comment on the appropriateness of the technical standards for used oil 

USTs. EPA considered the many comments received on this issue and has 

decided to include used oil USTs in the final regulation. Public 

comments received by EPA and proposed revisions to the final rule as 

they relate to the appropriateness of the technical standards for used 

oil USTs are discussed below.

In the preamble to the proposed regulations, EPA requested 

comments on the following issues relating to used oil:

oAre the petroleum UST requirements appropriate for recycled used 

oil and/or used oil bound for disposal?

oDo the minor constituents found in used oil (such as water and 

metals) alter the appropriateness of the requirements?

oIs it appropriate to have different standards for relatively 

smaller tanks, such as those used by used oil generators and 

burners, than for larger tanks, such as those used by used 

oil processors?

In addition, EPA also requested comment on the impact of the 

proposed regulations on the recycling of used oil.

In a supplemental FEDERAL REGISTER Notice (52 FR 48638, 

December 23, 1987), EPA requested comment on the appropriateness of 

using alternative methods of release detection for used oil USTs, to 

supplement those listed in § 280.41 of the proposed rule. The Agency 

specifically requested comments on the use of static inventory control 

as a method of release detection for smaller used oil USTs. This 

request was prompted by the Agency's belief that some of the release 

detection methods proposed in § 280.41 may not be practical or effective

for used oil USTs due to the physical characteristics of used oil. On 

the other hand, the Agency believes that the static inventory method of 

release detection may be very effective and practical for use with small 

used oil USTs. "Static inventory control" has been renamed as "manual 

tank gauging" in the final rule and in the rest of this preamble's 

discussion of this method of release detection.

The Agency believes that the risks associated with releases 

from used oil USTs may be different from those of other USTs, but the 

overall level of risk is similar to that of other petroleum products. 

Releases from used oil USTs may be less likely to occur than from 

petroleum USTs, but the health risks posed may potentially be greater 

because of the possibility of contaminants in the used oil. The 

appropriateness of further regulation, under RCRA Subtitle C, will be 

determined by results of studies currently in progress. At this time, 

the Agency has determined that used oil USTs should be regulated under 
Subtitle I because there is evidence of leaks that indicates a 

significant threat to human health and the environment.

In reply to EPA's request for comments about the 

appropriateness of the proposed regulation for used oil USTs, public 

comment was divided. Several commenters stated that used oil USTs 

should be covered by Subtitle I regulations because the risk to ground 

water was essentially the same as for other petroleum products, and that 

management of all underground tanks at a facility that had both used oil 

tanks and other Subtitle I regulated tanks (e.g., a service station) 

would be facilitated by a single, inclusive regulation (Subtitle I). In 

contrast, some commenters stated that the risk from used oil USTs was 

insignificant and, thus, used oil USTs should permanently be exempted 

from regulation. Others stated that used oil USTs should be regulated 

under RCRA Subtitle C because the hazardous constituents in used oil 

make it more dangerous than other petroleum products.

The Agency agrees with those commenters who noted that used 

oil presents risks similar to other petroleum products and that Subtitle 

I regulations are appropriate. Today's final rule reflects this by 

applying the petroleum UST requirements to used oil USTs, with limited 

exceptions discussed below. Releases from both used oil USTs or other 

petroleum USTs can be prevented, or at least limited, by sound 

management practices. As a result, the Agency has decided to require 

used oil USTs to meet the same upgrading, operation and maintenance, 

corrosion protection, corrective action, and closure requirements that 

are applicable to other petroleum USTs.

The Agency received comments requesting an exemption from 

Subtitle I regulations for small tanks. Recommended cutoff sizes ranged 

from 100 to 3,000 gallons. In addition, several commenters also 

requested regulatory exemptions for small vessels used to trap used oil, 

as well as tanks holding regulated substances for short time periods. 

As discussed above, in today's final rule EPA is exempting from the 

regulations USTs that are 110 gallons or less. Thus, small traps are 

excluded from regulation. With respect to tanks that hold regulated 

substances for short periods of time, today's rule includes an exemption 

for emergency spill collection tanks. The regulations do, however, 

apply to any other used oil USTs, the majority of which are the 500- and 

550-gallon tanks often found at gasoline service stations. Most of 

these USTs are old and are believed to be a common source of releases of 

used oil. USTs that contain used oil that is used as substitute for 

heating oil are excluded.

The Agency received several comments noting particular 

characteristics associated with used oil or used oil USTs that make some 

of the proposed technical standards in Part 280 inappropriate for used 

oil USTs holding less than 1,100 gallons. In response to these 

comments, today's final rule contains different requirements for small 

used oil USTs in two areas: release detection and overfill/spill 

protection. First, with respect to release detection, many commenters 

noted their support for manual tank gauging (formerly called "static 

inventory control") by itself as an alternative leak detection method 

for used oil USTs. Today's final rule allows the use of this 
alternative release detection method as the sole method of release 

detection for any petroleum UST with a capacity of 550 gallons or less. 

Manual tank gauging may be used in combination with periodic tank 

tightness testing on petroleum tanks with a capacity between 55 and 

1,000 gallons. (These provisions are discussed in more detail in 

section IV.D. of this preamble.)

Today's final rule also provides an exemption from the rule's 

spill and overfill protection controls for USTs that are filled in small 

increments. (This is also discussed in more detail later in this 

preamble under spill and overfill prevention for new USTs.) The Agency 

agrees with the commenters that used oil USTs that are filled manually 

in small increments do not pose the same risk to human health and the 

environment from spills and overfills as other USTs.

The Agency received additional comments related to design 

standards and agrees with those who requested cathodic protection for 

new used oil tanks. In addition, EPA is requiring that owners and 

operators upgrade or replace their used oil USTs according to the time 

period of today's final rule (10 years). EPA disagrees, however, with 

the commenters who argued that these tanks should be subject to 

secondary containment. Because the physical and chemical 

characteristics of used oil are similar to petroleum products, the 

release detection and corrective action technologies should be similarly 

applicable to used oil. Thus, the final rule subjects used oil USTs to 

the release detection requirements applicable to petroleum UST systems 

rather than secondary contaminant required for hazardous substance UST 

systems.

h. Airport Hydrant Fueling Systems

A number of commercial airports and airports at Department of 

Defense bases use hydrant fueling systems. These systems generally 

consist of one or more bulk storage tanks that may be either below or 

aboveground and that are connected by underground piping to various 

aircraft fueling locations on the airport. Hydrants, otherwise known as 

fuel dispensers, are connected to the pipe networks and dispense fuel 

into aircraft. These systems are, in some cases, very large in size and 

contain great volumes of fuel. Many airports have miles of piping, 

which is typically 8 to 24 inches in diameter, and the total capacity of 

the systems can be many millions of gallons.

Through a brief investigation of these systems, the Agency 

believes that some of these systems do not meet the statutory definition 

of an UST system, and are thus outside of the jurisdiction of Subtitle 

I. Hydrant systems that have aboveground storage tanks are not 

regulated tank systems unless 10 percent or more of the capacity of the 

system is in the belowground pipelines.

However, hydrant systems with belowground storage tanks and 

those with aboveground storage tanks but whose pipelines account for 10 

percent or more of the system's capacity are within to Subtitle I 

jurisdiction as UST systems. The special problems posed by requiring 

hydrant systems to meet many of the requirements in today's final rule 
have motivated the Agency to look further at these systems, and have led 

to today's deferral of regulations for these systems.

The Agency continues to examine questions regarding the 

construction, operation, maintenance, and monitoring of hydrant systems. 

Preliminary information indicates that hydrant systems typically have 

cathodic protection, and are monitored for leaks on a daily, monthly, 

and annual basis. Inventory monitoring is often used, but the 

sensitivity of this technique is very limited due to the large volume 

these systems typically handle. No single leak test, however, appears 

to be an industry standard.

Since proposal, the Agency has become aware of several leak 

incidents from hydrant systems that resulted in environmental damage. 

Because of limited information on this subject, however, the Agency is 

unclear about the extent of this problem. In addition, to the nature of 

these systems, especially the typically large amount of piping, certain 

requirements in today's rule (such as leak detection for piping systems) 

may not be feasible for hydrant systems. For these reasons, the Agency 

is deferring regulation of Subparts B, C, D, E and G for all airport 

hydrant systems, including the underground tank portions of those

systems, to allow more time to gather information.

i. Backup Diesel Tanks at Nuclear Facilities

Following publication of the proposed regulations, a 

commenter raised the issue of the applicability of the UST regulations 

to tanks at nuclear power plants that store diesel fuel for use in 

emergency situations. According to the commenter, these tanks are 

already extensively regulated by the Nuclear Regulatory Commission 

(NRC), and further regulation by EPA could result in an overly 

burdensome program if the regulations were inconsistent. Not only would 

these nuclear facilities be required to meet dual regulatory programs, 

but structural changes to the systems as a result of the UST regulations 

could result in an amendment to the plant's license, according to a 

commenter. The commenter also pointed out that any shutdown of the 

backup fuel system (e.g., for retrofitting) could result in the entire 

nuclear power plant being shut down.

The Agency is today deferring the requirements of Subparts B, 

C, D, E and G for these tanks pending completion of a review of the NRC 

regulations (10 CFR 50 Appendix A) governing these tanks to determine 

whether further regulation is necessary to protect human health and the 

environment or would be inconsistent with NRC regulations for proposes 

of section 1006. If this research indicates that the NRC regulations 

are not adequate or are not as complete as the UST regulations, EPA may 

require these tanks to be subject to Subtitle I regulations, or it may 

develop a separate set of standards applicable to this class of tank.
j. UST Systems Associated with Emergency Generators

In today's rule, EPA is deferring Subpart D requirements for 

UST systems associated with emergency power generators. Such tanks are 

common in the telephone industry and the electric utility industry. 

These tanks often store diesel fuel which serves as a source of backup 

power in remote locations (for example, at telephone switching 

locations). This is a deferral of the release detection requirements 

only; owners and operators of these systems must comply with all other 

subparts of this rule.

Several commenters argued that these tanks should not be 

regulated at all for the following reasons: they are generally small in 

size (typically under 500 gallons); most are less than 5 years old; they 

are often at unmanned stations in remote locations; they contain diesel 

fuel, which is less mobile than gasoline due to its higher viscosity; 

and many are filled only annually.

The Agency does not agree that these reasons merit an 

exclusion from the UST regulations. The requirement that these tanks be 

monitored each month is unworkable, however, because they are often 

located in remote areas and are visited very infrequently. Therefore, 

EPA is deferring Subpart D requirements for these tanks to allow time to 

develop workable release detection requirements for these tank systems.

4. Definitions

The following sections address many of the terms that are 

used in the statutory language and elsewhere in the final regulations. 

Since proposal, many terms have been redefined or clarified as a result 

of comments. The following sections contain the revised definitions, 

the rationale for the changes, and the Agency's interpretation of these 

terms.

a. Definitions of Terms in the Statute

(1) Underground Storage Tank. 

Underground storage tank is defined in the statute as any one 

or a 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.

Today's rule sets forth the following definitions for terms 

used in the statutory definition of underground storage tank:

(a) 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.

Several commenters stated that the definition of tank in the 

proposed rule was too broad, and included devices that do not store 

regulated substances but rather use, treat, collect, or capture 

regulated substances. By expanding the scope of tank beyond just 

storage tanks, say the commenters, EPA departed from its Congressional 

mandate and created a program that is overly inclusive and difficult to 

manage. The commenters also argued that the inclusion of hydraulic lift 

tanks, electrical equipment, oil-water separators, sumps, treatment 

tanks, and other devices not normally regarded as storage tanks would 

overwhelm the Agency's ability to adequately enforce the regulations. 

Also, the added burden of regulating these devices would be 

disproportionate to their potential environmental harm. Few of these 

devices have documented leak histories, according to the commenters.

Throughout the development of the UST regulations, where 

there has been ambiguity in the terms defining the jurisdiction of the 

Subtitle I program, it has been the Agency's policy to define the scope 

of the UST regulations broadly and interpret the exclusions relatively 

narrowly. By taking this approach, the Agency hoped to avoid 

prematurely eliminating from its jurisdiction tanks that may pose an 

environmental threat. This policy has afforded the Agency the 

opportunity to gather more information on the various classes of tanks 

in the potential regulated universe. EPA has retained the prerogative 

to narrow the scope of the program by regulation rather than statutory 

interpretation, taking into account potential environmental and health 

risks, implementability, and administrative burden. The Agency decided 

that this approach would result in a program that provides maximum 

protection to human health and the environment while taking into account 

the regulatory burdens associated with the program. Further explanation 

of these regulatory exclusions is found earlier in this preamble under 

IV.A.2. Regulatory Exclusions, many of which deal with precisely those 

tanks about which commenters expressed concern.

Accordingly, EPA disagrees with commenters who argued that 

EPA's definition of "tank" results in an unauthorized expansion of its 

regulatory program under Subtitle I. Although EPA acknowledges that 

this program includes only "storage" tanks, Congress defined "storage" 

in section 9001 of RCRA as "containing an accumulation of regulated 

substances." EPA's interpretation of the Subtitle I jurisdiction to 

encompass any devices holding an accumulation of any regulated 

substances (unless subject to a statutory exclusion) is thus not 

inconsistent with the statute. Moreover, this definition is the same as 

that which has been used in the Subtitle C tank program for years.

(b) Underground pipes connected thereto means all 

underground piping, including valves, elbows, joints, flanges, and 

flexible connectors attached to a tank system through which regulated 

substances flow. For the purpose of determining how much piping is 

connected to any individual UST system, the piping that joins two UST 

systems should be allocated equally between the systems. Tanks that are 
simply manifolded together are considered as one UST system. However, 

if an exempt tank is connected by piping to a regulated tank, half of 

the piping is allocated to each tank system. This allocation of 

connected piping is an attempt to reconcile two conflicting statutory 

provisions: section 9001(1) states that an UST system includes the tank 

and all underground pipes connected thereto but also states that a 

statutorily excluded UST system also includes all of the piping 

connected to it. As a result, half of the piping is allocated to the 

regulated tank system and half to the excluded tank system if two are 

connected.

In the RCRA Subtitle C tank rules, the starting point of the 

"connected piping" is the point at which the contained substance is 

initially considered to be a hazardous waste. It should be noted that 

the above terms as they apply here, while similar, are different than 

the Subtitle C definition.

(c) Regulated Substance. Today's definition of "regulated 

substance" in the final rule codifies the statutory definitions of 

"regulated substance" and "petroleum" and provides additional 

clarificati on concerning the coverage of certain substances and 

mixtures of these substances under the regulations.

(i) Overview. In the April 17 proposal, the Agency codified 

the statutory definition of regulated substance. Thus, "regulated 

substance" was defined to include: (1) any substance listed under 

section 101(14) of CERCLA, except those regulated as hazardous waste 

under Subtitle C of RCRA; and (2) petroleum, including crude oil or any 

fraction of crude oil that is liquid at standard conditions of 

temperature and pressure. The term "petroleum" was also separately 

defined as crude oil, crude oil fractions, and refined petroleum 

fractions including gasoline, kerosene, heating oils, and diesel fuels. 

The proposal addressed mixtures of petroleum and any hazardous 

substance with a "50 percent rule," and under which, for example, an UST 

system containing a mixture that was 50 percent or more petroleum was 

proposed to be a "petroleum UST system."

In the Supplemental Notice of December 23, 1987, the Agency 

proposed further clarification of these definitions by requesting public 

comment on a specific list of substances and blends that would be 

subject to the petroleum UST requirements. This list was intended to be 

comparable to the list of CERCLA hazardous substances (not including 

hazardous wastes). Thus, an owner or operator would have to comply with 

the UST regulations only if one or more of the stored substances were on 

either of the two lists of regulated substances. The proposed list of 

petroleum substances would also be used to determine, for purposes of 

release detection requirements, if a substance would be regulated as a 

petroleum UST system.

The few comments the Agency received about the proposed 

definition of regulated substance asked for further clarification of the 

term petroleum. The commenters' concern was whether the release 

detection requirements for new hazardous substance USTs (i.e., secondary 
containment), or those for new petroleum USTs, applied to particular 

substances. EPA also received numerous comments on the proposed list of 

petroleum substances contained in this Supplemental Notice. In general, 

most commenters expressed preference for this proposed list because it 

was more specific and clarified which substances had to meet the release 

detection requirements for petroleum USTs. However, some other 

commenters questioned this approach because of the difficulty in 

preparing a complete list and the loss of flexibility such a specific 

list would entail as the composition of petroleum products changed over 

time. Numerous commenters provided suggestions for adding or deleting 

specific substances from the list.

In today's final rule, the proposed list of petroleum 

substances in the Supplemental Notice is not used, although the general 

categories from the list have been included in the final definition of 

regulated substance. Thus, the definition of regulated substance 

retains the statutory language that was originially proposed, except 

that it has been revised to reference the petroleum refining process and 

include a list of seven basic categories of petroleum or petroleum-based 

substances considered by EPA to be "regulated substances." This 

addition to the federal definition is intended to respond to those 

commenters who requested more clarity about the scope of petroleum 

substances included within Subtitle I jurisdiction. The final rule also 

includes definitions for hazardous substances UST systems and petroleum 

UST systems for the purpose of clarifying, as requested by some 

commenters, which regulated substances are subject to the secondary 

containment requirements for new USTs storing hazardous substances and 

which are subject to the release detection requirements for new USTs 

storing petroleum or petroleum products. (These terms and their use to 

discern how mixtures are treated are discussed in section IV.A.4.b.)

(ii) Revisions in the final rule and public comments on the 

proposal. In the final rule regulated substance is defined as: "(a) 

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 (b) petroleum, including crude oil or any fraction thereof that 

is liquid at standard conditions of temperature and pressure (60 degrees 

Fahrenheit and 14.7 pounds per square inch absolute). The 'regulated 

substance' includes but is not limited to petroleum and petroleum-based 

substances comprised of a complex blend of hydrocarbons derived from 

crude oil through processes of separation, conversion, upgrading, and 

finishing, such as motor fuels, jet fuels, distillate fuel oils, 

residual fuel oils, lubricants, petroleum solvents, and used oils." In 

summary, the proposal's codification of the statutory definition of 

"regulated substance" has been retained in sections (a) and (b) of the 

final definition (see above). Also, the proposal's elaboration of the 

meaning of petroleum in a separate definition of the term has been 

deleted (see section (iii) below), but several general categories in 

that proposed definition have been listed in the final definition of 

regulated substance to respond to some commenters' requests for 

clarification of the scope of the substances covered by the regulations.
The first part of today's final definition of regulated 

substance (section (a)) refers to the specific list of substances (both 

chemicals and discarded chemical products) that are defined by 

regulation under CERCLA (see 40 CFR Part 302). The Subtitle I program 

covers all hazardous substances except those that are hazardous wastes. 

Few comments were submitted concerning this list or section (b) of the 

proposed definition (the statutory definition of petroleum). The two 

questions raised in most public comments were (1) whether the storage of 

a particular substance was regulated under Subtitle I, and (2) what 

release detection was required for new UST systems storing a particular 

substance (see section (iii) below).

EPA originally proposed to define petroleum as crude oil, any 

fractions of crude oil and refined petroleum fractions, such as 

gasoline, kerosene, heating oils, and diesel fuels. In the Supplemental 

Notice to the proposal, EPA requested comment on the appropriateness of 

adding to the definition a specific list of substances that was based on 

the fundamental petroleum refinery process. Many commenters agreed with 

the proposed use of the crude oil separation processes as the basis for 

determining which substances should be subject to petroleum UST 

standards. However, others believed that basing the definition of 

petroleum strictly on the steps in the separation process was 

inappropriate. These commenters pointed out that this approach could 

result in similar substances being regulated differently, such as 

unleaded motor gasoline being considered a petroleum substance and 

leaded motor gasoline a hazardous substance because lead is added in 

steps subsequent to basic separation processes. Other commenters 

pointed out the difficulty in determining the exact point in the 

refinery process at which a substance is considered petroleum and at 

which point it becomes a chemical product distinct from petroleum.

In the refinery process, separation involves two steps: 

atmospheric and vacuum distillation. Heat is applied to crude oil, 

which separates into individual fractions because of differences in 

boiling points or boiling ranges. Some of these fractions can be used 

directly from a distillation tower; however, many of the products must 

go through further treatment. This treatment is known as conversion, 

which includes such processes as hydrocracking, catalytic cracking, 

coking, and alkylation. These processes are used to change the 

molecular weight and boiling ranges of the fractions. Upgrading is the 

process of improving the quality of the petroleum fraction by removing 

sulfur, nitrogen, and oxygen. The heating involved with this process 

adds stability and removes waxes, allowing lower pour points. Finishing 

does not mean distillation to pure chemical products, but is the final 

step before a petroleum product is sold at retail. An example of 

finishing is the addition of certain chemicals to motor gasoline. 

Additives may include octane enhancers, which either raise or lower 

octane ratings, dyes for product identification by color, and detergents 

that remove deposits from engines. These additives may be listed 

hazardous substances. The complexity of this process, the variety of 

chemical products produced, and the variety of chemical additives mixed 

with petroleum products in the refinery process has led to some 

confusion about which substances are "petroleum" or "hazardous 

substance" under Subtitle I.
To overcome this confusion and respond to comments received 

on the proposal, the final rule does not include a separate definition 

of petroleum. Instead, the final rule language for "regulated 

substance" has been amended to clarify what petroleum and petroleumbased substances, hazardous substances, and mixtures are within the 

regulated universe.

The final definition of regulated substance has been revised 

to refer to products from the refinery process, and it lists seven 

general categories of petroleum and petroleum-based substances so that 

the breadth of the coverage of the regulations is clear. Each of these 

general categories in fact consists of many specific individual products 

or substances. By not individually listing these different products and 

grades, EPA intends that any future adjustments in specific product 

composition (for example, changes made to respond to market demands) 

will not affect the product's classification as a "regulated substance." 

These seven categories correspond to the major categories in the list 

of petroleum substances and mixtures proposed in the Supplemental 

Notice. Nearly all petroleum products in use today are included in the 

seven categories listed in the definition. The general reference in the 

definition to the products from the refining process (discussed above) 

will aid in identifying the remaining unlisted regulated substances. 

Under this approach, EPA will not need to continually update the list 

(for example, motor gasolines is a category of regulated substance now 

and in the future, although new blends of motor gasoline, such as "midgrade," may be developed or new additives may be used).

The Agency believes that this approach will make it easier to 

determine the regulatory status of an individual substance or blend 

under Subtitle I and ease the implementation burdens on the UST owner 

and operator, and the implementing agency. Any owner or operator trying 

to determine whether a tank system contains "regulated substances" and 

is subject to Subtitle I requirements must first determine if the 

substance belongs to one of the seven general categories of regulated 

petroleum substances. If not, then the owner or operator next must 

determine whether the stored material is included within the production 

process and physical properties description for petroleum products. If 

not, then the owner or operator must finally determine whether the 

substance is listed as a hazardous substance under section 101(14) of 

CERCLA (see 40 CFR Table 302.4), except for those listed as "hazardous 

wastes" under Subtitle C of RCRA. If the substance has not met one of 

these three definitions, then it is not a regulated substance.

(iii) Petroleum. The proposed definition of petroleum has 

been deleted from the final rule. A separate definition of petroleum 

was not included in the final rule because now no regulatory 

distinctions are based solely on whether the stored substance is 

"petroleum" or a "hazardous substance." However, regulatory 

distinctions concerning the selection of release detection equipment are 

based on whether a new tank system is a "petroleum UST system" or a 

"hazardous substance UST system." All other technical requirements are 

the same for all UST systems storing regulated substances.
In response to commenters' concerns about how to determine 

what type of release detection is applicable to a new UST system, the 

final rules include definitions that distinguish between "petroleum UST 

systems" and "hazardous substance UST systems." Owners and operators of 

new petroleum UST systems may utilize a variety of release detection 

methods because petroleum or petroleum-based substance releases are more 

predictable in their fate and transport underground, create relatively 

well-known exposure risks, and are subject to more widely available 

release detection and corrective action technologies. For regulatory 

purposes, petroleum UST systems may store petroleum or petroleum-based 

substances, petroleum and de minimis hazardous substance mixtures (e.g., 

used oil), or hazardous substances with properties similar to petroleum 

products. Thus, the types of stored substances subject to the release 

detection requirements for new petroleum UST systems are somewhat 

broader in scope than what constitutes simply "petroleum." This is 

reflected in a revised definition of "petroleum UST system," which 

includes a replacement of the proposal's 50-percent rule for petroleumhazardous substance mixtures with a de minimis rule. (See the 

discussion in section IV.A.4.b. concerning the definitions of "hazardous 

substance UST system" and "petroleum UST system.")

The Agency will continue to use the statutory definition of 

"petroleum" for purposes of the LUST Trust response program under 

section 9003(h). Except for the requirement that petroleum must be a 

liquid at standard conditions of temperature and pressure, the term has 

the same definition as the term "petroleum" defined under CERCLA 

sections 101(14) and 101(33). The Agency interprets these terms to 

include the same substances, i.e., crude oil and refined fractions of 

petroleum, including gasoline and diesel fuels. The term "petroleum" 

includes the inherent "hazardous substance" constituents in crude or 

refined oil but does not include contaminants present in or mixed with 

the petroleum. Under section 9003(h), the Agency may undertake or order 

corrective action with respect to a release of petroleum from an UST 

system. The response program, however, is not limited to UST systems 

containing solely petroleum but, rather, requires only that the release 

from the UST contain petroleum. Thus, petroleum-hazardous substance 

mixtures would also be subject to the section 9003(h) corrective action 

authorities. This is consistent with Congressional statements 

concerning the jurisdiction of the section 9003(h) program. (See H.R. 

Conf. Rep. No. 962, 99th Congress, 2d. Sess., p. 228 (1986).)

(d) A tank is 10 percent or more beneath the surface of the 

ground if its volume (including the volume of its connected underground 

piping) is 10 percent or more beneath the ground surface or otherwise 

covered with earthen materials.

This definition reflects the intent of the UST regulations to 

govern underground tanks that could leak directly into the ground 

undetected. Thus, the following types of tanks are included within UST 

jurisdiction: tanks that are underground; in-ground open-top tanks; and 

tanks that are above grade but are covered with earthen materials (for 

example, to comply with fire codes). Tanks that are above the ground 
surface and are covered with non-earthen materials are not included 

within the scope of this definition.

The phrase "so that physical inspection is precluded" has 

been removed from this definition since proposal. One commenter argued 

that this phrase could be construed to bring under the jurisdiction of 

the UST program any totally aboveground tank that is permanently covered 

or shielded from view (e.g., by insulation). EPA agrees with this 

commenter that such tanks, as long as their volume, including the volume 

of connected underground piping, is not 10 percent or more beneath the 

surface of the ground, are not the focus of this program and should not 

be subject to UST regulations. These tanks are not subject to the same 

corrosive forces as are underground tanks and may be more easily 

inspected visually than other belowground tanks.

Other commenters referred to aboveground tanks that are 

enclosed in concrete vaults and are surrounded by inert material such as 

sand or vermiculite. The commenters believed that these tanks should 

not be defined as USTs. Under the changes to this definition in today's 

rule, aboveground tanks surrounded by sand would be within the scope of 

these regulations, because sand is an earthen material and has the 

potential to create corrosion. Vermiculite is not considered an earthen 

material and would not promote corrosion, and, therefore, tanks that are 

covered by this material are not considered USTs.

The statute excludes nine types of tanks from the definition 

of underground storage tank. Eight of these nine types of exclusions 

are described below. The ninth, on septic tanks, is not discussed 

because no changes have been made to the proposal and no comments were 

submitted to EPA on this exclusion.

(2) Farm or Residential Motor Fuel Tank Exclusion. 

The first group of tanks excluded by the statute is "farm or

residential tanks of 1,100 gallons or less capacity used for storing 

motor fuel for noncommercial purposes." Following are definitions for 

the key terms of this exemption.

(a) A farm tank is a tank located on a tract of land devoted 

to the production of crops or raising of animals, including fish. 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. This definition, as promulgated, is unchanged from the 

proposal.
One commenter argued that tanks at golf courses are 

essentially the same as tanks at sod farms; both types are used to hold 

fuel in support of sod and turf development. For these reasons, the 

commenter contended, these tanks deserve to be included under the farm 

exemption. The Agency does not agree that the similarities between sod 

farms and golf courses merit inclusion of tanks at golf courses within 

the farm tank exclusion. The Agency does not believe the term "farm" 

under section 9001 of RCRA, reasonably interpreted, includes golf 

courses or other places dedicated primarily to recreational, aesthetic, 

or other non-agricutural activities.

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(b) Motor Fuel in today's rule means petroleum or a 

petroleum-based substance that is motor gasoline, aviation gasoline, No. 

1 or No.2 diesel fuel, or any grade of gasohol, and is typically used in 

the operation of a motor engine.

As originally proposed, motor fuel was defined as petroleumbased fuel used in the operation of an engine that propels a vehicle for 

transportation of people or cargo. In the general interpretation of 

this phrase, motor fuel was limited to motor gasoline and diesel fuel 

used in automobiles, trucks, and buses. Many commenters felt that 

gasohols should be added to the list of motor fuels, because alcoholtype fuels are an alternative energy source encouraged by many states 

such as California. Commenters also felt that the term motor fuel 

should not be restricted to vehicles used for transportation purposes 

because some motors are stationary engines. The Agency agrees that the 

proposed definition was unnecessarily restrictive.

The final rule lists five types of motor fuel that are 

typically used to operate motor engines. Gasohols are included as motor 

fuels because EPA agrees with public comment that these are commonly 

used as and understood to be motor fuels. The proposed language 

restricting "motor fuel" to fuels used in transportation has been 

deleted from the definition because the term "motor fuel" does not in 

itself describes a use of the fuel, but rather describes a type of fuel. 

The statutory exclusion already contains a "use" limitation by 

restricting the exclusion to motor fuels stored for "noncommercial" 

purposes.

Accordingly, today's final rule defines motor fuel in terms 

of specific types of fuel. The definition lists typical uses to give 

descriptive, not restrictive, information about these substances. The 

final rule thus includes fuels used in stationary motors. The structure 

of this definition parallels that of heating oils.
(3) Heating Oil Tanks Exclusion.

The second group of tanks excluded from UST jurisdiction by 

statute are tanks used for storing "heating oil for consumptive use on 

the premises where stored." Following are definitions for key terms of 

this exclusion: 

(a) Heating Oil means petroleum that is No. 1, No.2 , No. 4-

light, No. 4-heavy, No. 5-light, No. 5-heavy and No. 6 technical grades 

of fuel oil; other residual fuel oils (including Navy Special Fuel Oil 

and Bunker C); and other fuels when used as substitutes for one of these 

fuel oils. Heating oil is typically used in the operation of heating 

equipment, boilers, or furnaces.

The proposed rule defined heating oil as either one of eight 

technical grades of fuel oil (No. 1; No. 2; No. 4-light; No. 4-heavy; 

No. 5-light; No. 5-heavy; No. 6; and residual) or fuel oil substitutes 

such as kerosene or diesel when used for heating purposes. This 

definition has been revised in the final rule to clarify which technical 

grades of fuel oil the Agency believes are heating oil. In addition, 

the definition has been revised in response to comments on the use of 

heating oil substitutes.

The list of grades of fuel oils has been reworded because, 

since proposal, the Agency has discovered that "residual" is not a 

specific technical grade of fuel oil, but refers to several grades of 

fuel derived from certain operations in the refinery p rocess. Also, 

Navy Special Fuel Oil and Bunker C are included in the final definition 

as examples of residual fuels.

Several commenters suggested changes to the definition to 

modify the applicability of the heating oil exclusion to tanks storing 

fuel oil substitutes. Several commenters stated that both No. 2 diesel 

fuel and kerosene should be included as heating oil because their 

chemical makeup is similar to each other and No. 2 fuel oil. Additional 

commenters thought that the exclusion should not be limited to oil used 

for heating purposes. The Agency agrees that the heating limitation is 

inconsistent with the statutory language of the exclusion that limits 

"use" only by requiring "consumptive" use. The final rule definition, 

therefore, includes heating as a typical use of the fuels but does not 

limit the exclusion to fuels so used. The exclusion does, however, 

limit the use of substitutes to those situations where the substitute is 

actually used in place of one of the technical grades of fuel oil. For 

example, tanks that contain used oil at a typical retail gas station are 

not excluded unless the used oil is consumed on-site as a substitute for 

fuel oil (burned in an on-site space heater, for example). Tanks that 

store used oil awaiting recycling pickup are not heating oil tanks. 

Another example of a tank that is not a heating oil tank is one that 

stores diesel fuel for an on-site motor generator. Even though diesel 

fuel is sometimes burned in boilers as a substitute for heating oil, it 

is the fuel of choice for internal combustion engines. It is, thus, not 

a substitute for one of the technical grades of heating oil in this 

situation.
Thus, heating oil is defined in the final rule in terms of 

specific grades of oil or their substitutes. A sentence has been added 

to the definition listing typical uses of heating oil. This list 

provides descriptive, not restrictive, information about these 

substances and parallels the definition of motor fuel.

(b) Consumptive use means used on the premises. 

Accordingly, 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.

In the preamble to the proposed rule, EPA stated that 

"consumptive use" was not intended to be limited to only space heating 

purposes, and described other uses of heating oil that would qualify for 

this exclusion. This definition has been modified since the proposed 

rule to clarify that tanks holding heating oil for any on-site use, such 

as heating or to power a generator, are exempt from regulation.

Several commenters supported this interpretation of 

consumptive use. Heating oil used to produce steam, process heat, 

electricity, and emergency power were among the consumptive uses that 

the commenters thought should be included in the heating oil exclusion. 

Today's definition clarifies that these uses are within the scope of 

this exclusion.

Several commenters argued that tanks storing diesel fuel for 

use in emergency generators should be exempt as tanks storing heating 

oil. As explained above, no restrictions are being placed on the use of 

the heating oil under this exclusion, except that it be used 

consumptively on-site. 

(c) 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 heating units using heating oil that serve 

more than one building on the same property would be excluded.

In addition, several commenters provided suggestions that 

would result in narrower interpretations of this exclusion by regulating 

one of the following segments: all residential and commercial tanks; 

all commercial tanks; all tanks at commercial and government buildings; 

all residential buildings of six or more units; or all tanks above a 

certain size. The Agency recognizes the concerns expressed by these 

comments but believes that the statutory language prevents adoption of 

such suggestions. Under the statute, the exclusion of heating oil tanks 

is not limited to certain categories of heating oil tanks (e.g., only 

residential or only tanks less than 1,100 gallons). Congress did 

recognize, however, that heating oil tanks may require some regulation 
and required that EPA study this universe of exempt tanks and make 

recommendations concerning regulation (section 9009).

(4) Pipeline Facilities Exclusion.

The fourth exclusion covers "any pipeline facility (including 

gathering lines) (1) regulated under the Natural Gas Pipeline Safety Act 

of 1968 (49 USC App. 1671, et seq.), (2) regulated under the Hazardous 

Liquid Pipeline Safety Act of 1979 (49 USC App. 2001, et seq.), or (3) 

which is an intrastate pipeline facility regulated under state laws 

comparable to the provisions of the laws referred to above.

"Pipeline facilities (including gathering lines)" include new 

and existing pipe rights-of-way and any equipment, facilities, or 

buildings used in the transportation of gas (or hazardous liquids, which 

include petroleum and any other liquid designated by the Secretary of 

Transportation) or the treatment of gas or designated hazardous liquids 

during the course of transportation.

The definition of pipeline facilities was adapted from the 

definition of that term as used in the Natural Gas Pipeline Safety Act 

of 1968 (NGPSA) and the Hazardous Liquid Pipeline Safety Act of 1979. 

"Pipeline facility" may also include any such intrastate facility as 

defined and regulated under state laws comparable to these two federal 

statutes. This definition includes sumps, drip tanks, skimmer pits, 

lubrication oil collection devices, and any other containers that are 

directly connected to regulated oil or gas pipelines or gas plants. This 

equipment would qualify as equipment used in the transportation of gas 

or hazardous liquid or the treatment of gas or hazardous liquids during 

the course of transportation.

One commenter pointed out that the definition of pipeline 

facilities in this rule differs from the definition which appears in the 

NGPSA. This commenter believed the Agency was mandated by Congress to 

adopt the definition from the NGPSA. The Agency intended that the 

definition that appears in these regulations mean the same as that 

definition that appears in NGPSA; the word changes were only for 

abbreviation. The Agency has retained the wording from the proposed 

rule.

(5) Surface Impoundments, Pits, Ponds and Lagoons Exclusion. 

The fifth exclusion covers any "surface impoundment, pit, 

pond or lagoon." A surface impoundment is defined as a natural 

topographic depression, man-made excavation, or diked area formed 

primarily of earthen materials (although it may be lined with man-made 

materials) that is not an injection well.

Since the proposed regulations, this definition has been 

changed and no longer stipulates that the surface impoundment be 

designed to hold an accumulation of regulated substances. This phrase 

created confusion among commenters and was considered unnecessary.
(6) Storm-Water or Wastewater Collection Systems Exclusion. 

The sixth exclusion covers a "storm-water or wastewater 

collection system." A storm-water or wastewater collection system is 

defined as all piping, pumps, conduits, and any other equipment 

necessary to collect and transport the flow of surface water runoff 

resulting from precipitation, or domestic, commercial, and industrial 

waste water to and from detention areas or areas where treatment is 

designated to occur. The collection of storm water and wastewater does 

not include treatment except where incidental to conveyance.

This definition is substantially the same as the proposed 

definition, with one addition to clarify that treatment is not included 

as part of a collection system. 

The Agency received several comments on the definition of a 

collection system and also on the applicability of the UST regulations 

to wastewater treatment tanks. In general, the commenters were critical 

of any attempt by the Agency to define collection system so that 

treatment tanks, including oil-water separators, would be regulated. 

The various reasons and arguments used by commenters are discussed 

below.

Several commenters stated that treatment tanks are logically 

included as part of the collection system, and that Congress intended to 

exclude the tanks from these regulations. The word "system" implies 

that everything related to the collection of storm water and wastewater, 

including piping and tanks, should be excluded, according to commenters.

Two commenters stated that it is illogical to exclude the 

pipes and pumps of a collection system but not the treatment tanks. The 

sole purpose of these tanks, one commenter pointed out, is to reduce the 

degree of contamination of the water and lessen the threat of 

environmental harm. Another commenter stated that regulation of 

wastewater treatment tanks would penalize those who pretreat at the 

request of a POTW, and regulation may discourage on-site treatment. 

Both comments disagreed with any attempt to regulate these tanks. 

Several commenters argued that treatment tanks, and in 

particular oil-water separators, should be excluded because they are 

flow-through process tanks. Several commenters believe that treatment 

tanks are already regulated under other federal laws, including the 

Clean Water Act and the Safe Drinking Water Act. Further regulation 

under Subtitle I would be unwarranted and unnecessary, according to the 

commenters.

EPA does not agree with commenters who argued that a 

collection system includes tanks where treatment is designated to occur. 

Collection and treatment are separate and distinct functions. The 

Agency continues to believe that the collection system includes all 

piping, pumps, and conduits that extend to and from areas where 

treatment is designated to occur.
The Agency does not believe that it is illogical to regulate 

wastewater treatment tanks, although their purpose is to lessen the 

concentration of regulated substances in the water. Such tanks serve as 

receptacles for regulated substances, and may leak as any other tanks 

may leak, with adverse results. To categorically exclude all such tanks 

from regulation may risk environmental damage.

EPA also does not agree with commenters who argued that 

treatment tanks, particularly oil-water separators, should be classified 

as flow-through process tanks and therefore excluded. Treatment tanks 

do not form part of a production process, so they cannot be classified 

as flow-through process tanks.

EPA does agree, however, with the commenters who argued that 

some wastewater treatment tanks are adequately regulated by other 

federal regulations. After reviewing the comments, EPA has decided not 

to regulate any wastewater treatment tanks that are part of a wastewater 

treatment facility that is subject to regulation under either section 

402 or 307(b) of the Clean Water Act. The primary reason for this 

decision is that, because such tanks are already subject to regulation 

under the CWA, additional regulation under Subtitle I is unnecessary to 

protect human health and the environment. Other wastewater treatment 

tanks may be excluded because they contain only de minimis

concentrations of regulated substances. Wastewater treatment tanks that 

are not subject to regulation by the CWA sections 402 or 307(b) and that 

contain greater than de minimis concentrations of regulated substances 

will continue to be deferred from regulation. This deferral reflects 

the Agency's uncertainty regarding the nature of these tanks and the 

appropriateness of the UST regulations to wastewater treatment tanks. 

More discussion on wastewater treatment tanks is provided under that 

heading in section IV.A.3.

(7) Flow-Through Process Tank Exclusion. 

The seventh exclusion covers any flow-through process tank. 

Under today's final rule, a flow-through process tank is a tank that 

forms an integral part of a production process through which there is a 

steady, variable, recurring, or intermittent flow of materials during 

the operation of the process. Flow-through process tanks do not include 

tanks used for the storage of materials prior to their introduction to 

the process or for the storage of finished products or by-products from 

the production process. 

Today's definition differs from the proposed definition in 

several respects. This exclusion now applies to tanks that are a part 

of a production process, rather than to tanks that are part of an 

industrial or commercial process. It now applies not only to tanks with 

steady or uninterrupted flow, but also to tanks with variable, 

recurring, or intermittent flow. The exclusion also now applies to 

tanks that hold intermediates. 
The scope of the flow-through process tank exclusion has been 

one of the most difficult to define and most controversial 

interpretative issues, due to the lack of legislative guidance and a 

commonly understood technical meaning, as well as the potential for the 

exclusions, broadly interpreted, to encompass nearly all of the UST 

universe.

Although the definition of the terms "flow-through" and 

"process" have undergone several changes since EPA's first 

interpretation in the April 1986 guidance, these changes have been 

intended to clarify the Agency's interpretation of the scope of the 

exclusion and not to fundamentally alter that interpretation. EPA 

believes that this exclusion encompasses tanks that are an integral part 

of a production process and through which materials flow during the 

operation of that process. Application of leak detection or other tank 

standards to such tanks would generally be difficult to implement and 

potentially disruptive to vital production processes. The changes to 

this definition since the April 1986 guidance have resulted from 

comments on the April guidance, on the proposed definition, and on the 

Supplemental Notice. These comments are discussed below.

The original definition of this term that appeared in the 

April 1986 guidance document defined flow-through process tank to 

include any tank that was part of a "manufacturing" process that had 

"steady or uninterrupted flow." The original definition did not refer 

to tanks that held intermediates. This definition was thought by many 

commenters to be too restrictive in two respects: they stated that not 

only manufacturing tanks but also other industrial and commercial tanks 

should qualify; and that the requirement that the flow be steady would 

mean many tanks that operate in a batch fashion outside the scope of 

this exclusion.

The Agency agreed to some degree with these early commenters 

and, thus, included in the 1987 proposal a different definition than the 

one that appeared in the 1986 guidance. The proposed definition applied 

to "industrial and commercial" tanks, rather than to "manufacturing" 

tanks. The definition continued to restrict this exclusion, however, to 

tanks with a "steady or uninterrupted" flow of materials but added 

"during the operation of the process" in an attempt to accommodate 

commenters' concerns regarding batch processes. The proposed definition 

also stipulated that tanks that stored intermediates were not flowthrough process tanks.

In the proposal preamble, the Agency expressed concern over 

what types of tanks would qualify as "flow-through process tanks" if the 

definition were expanded to include non-steady flow. Specifically, EPA 

was concerned that tanks at gasoline stations, airports, rental car 

agencies, and other such "commercial" locations could be construed to be 

flow-through process tanks if the flow of materials was allowed to be 

recurring. Thus, such an interpretation could exclude most tanks from 

the regulated UST universe. These concerns, in part, led to the 

issuance of a supplemental notice requesting comments on clarifying 

"process" to mean "production process" rather than "industrial and 

commercial process" as proposed in April 1987.
Several commenters addressed the issue of the types of 

facilities where flow-through process tanks may be located, in response 

to requests for comments in both the proposed rule and the supplemental 

notice. Comments in response to the proposed definition showed general 

agreement with the change (since the April guidance) to "industrial and 

commercial" from "manufacturing." One commenter stated that no 

qualifiers should be included on the term "process." Examples of nonmanufacturing processes given by one commenter included oil and gas 

production, gas processing, wastewater collection and treatment, and 

recycling tanks. Other commenters suggested that hydraulic lifts, oilwater separators, and electrical equipment should be flow-through 

process tanks. 

Several commenters supported the change proposed in the 

Supplemental Notice to "production process" from an "industrial or 

commercial process." According to commenters, this change "makes 

sense," "is in accordance with Congressional intent," and "clarifies 

that storage tanks are not flow-through process tanks." Several 

commenters, however, argued that the change to "production process" 

would be a narrowing of the exclusion that is not supported by 

Congressional intent. This change would also not be easier to 

implement, according to one commenter. One commenter suggested that 

flow-through process tanks used in the distribution of electric power 

were an example of a flow-through process tank that is clearly 

"industrial or commercial process," but is not necessarily "production." 

Another commenter stated that "production" implies a tangible good is 

produced, and thus a "production process" is no different than a 

"manufacturing process." Specifically, this commenter referred to tanks 

in the dry cleaning industry, which would be outside the scope of this 

exemption if a tangible good was required to be produced. 

With respect to the interpretation of the term "flowthrough," several commenters believed that the requirement that the flow 

be steady or uninterrupted (during the operation of the process) was too 

restrictive, and would result in the regulation of many tanks that the 

commenters believed qualify for this exclusion. For example, these 

commenters pointed out that many tanks in a process stream are batch 

tanks, where the flow of materials is recurring or interrupted. Such 

tanks are common in the chemical industry. The commenters also cited 

process tanks with variable flows, for which there is no flow some or 

most of the time, as examples of the type of tank that should be 

included in this exclusion. 

The preamble to the proposed rule discussed allowing tanks 

that have an interruption in steady flow due to periodic maintenance or 

emergency shutdown to remain within the scope of this exclusion. The 

proposal preamble also stated that if a flow-through process tank 

regularly stores materials during period of interruption, it is a 

storage tank and not a flow-through process tank. Several commenters 

stated that tanks that "store" substances under these circumstances 

should still qualify for this exclusion because it may not be possible 

to remove all the material from the tank, and that this requirement 
seemed to imply that these tanks must be completely empty when the 

process was not in operation. 

In the proposal preamble, the Agency also asked for comments 

on whether "integral to the process" would include governmentally 

required wastewater treatment tanks that are a necessary part of the 

industrial or commercial process. Several commenters stated that 

wastewater treatment tanks, including oil-water separators, should be 

considered flow-through process tanks because treatment of wastes is a 

process and is an integral part of any facility. One commenter stated 

that oil-water separators should not be considered flow-through process 

tanks because they are covered in UL 1316. 

The discussion of flow-through process in the proposal 

preamble stated that tanks that store intermediates were not flowthrough process tanks. Several commenters argued that tanks storing 

intermediates are a necessary part of the process in order for the 

process to be conducted safely and to allow for an adequate supply of 

raw materials to be used in batch-operated processes. They further 

stated that intermediate tanks store materials on a very temporary basis 

and consequently do not pose the same hazards as a tank that is in use 

at all times. 

EPA also requested factual information, in particular process 

diagrams, indicating what tanks should be excluded as flow-through 

process tanks, given the nature of the specific process and function of 

the tank. One commenter provided the following examples: holding tanks; 

feed tanks; mixing tanks; tanks that hold materials being cut in 

concentration; and other tanks in the process train.

As discussed above, the definition of flow-through process 

tank as promulgated today is different in several respects from the 

proposed definition. The major differences are: the substitution of the 

phrase "production process" for "industrial or commercial process"; the 

change to "steady, variable, recurring, or intermittent" flow from 

"steady or uninterrupted" flow; and that tanks storing intermediates are 

now included as flow-through process tanks.

With respect to the interpretation of the term "process," the 

Agency agrees with those commenters who supported the change to 

"production process" from "industrial and commercial process," and is 

incorporating that phrase into the definition of flow-through process 

tank. EPA does not agree with commenters who argued that this wording 

is an unauthorized narrowing of the interpretation of this term. In 

response to the commenter who stated that the word "production" implies 

"making" or "manufacturing," and that the phrase "production process" 

would then be interpreted as "manufacturing process," the Agency does 

not intend to limit this exclusion only to manufacturing processes. 

Rather, any process at manufacturing, commercial, or industrial 

facilities where a tangible good or service is produced or performed may 

be considered a production process. Production processes include a wide 

variety of facilities and processes, including many at petroleum 

refineries, chemical manufacturing facilities, and automobile assembly 

plants. EPA does not agree, however, that "process" should be 
unqualified. Allowing the interpretation of this term to be 

unrestricted could result in an unreasonable interpretation of this 

exclusion, which, in effect, removes virtually all tanks from UST 

regulation since a tank related to any process through which there is a 

periodic flow of materials describes most storage tanks.

The Agency has changed its previous definition to allow 

steady, variable, recurring, or intermittent flow. Based on comments 

received on the proposed rule, the Agency realized that the revised 

definition did not effectively include batch process tanks, contrary to 

the Agency's intention, because batch processing can involve flows that 

are other than steady or uninterrupted during the operation of the 

process. In addition, EPA limited "flow-through" to steady or 

uninterrupted flow, rather than "recurring" flow to avoid eliminating 

jurisdiction over tanks with periodic inflow and outflow, including UST 

systems at gasoline filling stations. The Agency now believes, however, 

that by allowing variable or recurring flow, but limiting this exclusion 

to production processes, this concern is no longer relevant. Tanks that 

do form a part of a production process are often operated in a batch 

fashion, where inflow and outflow are periodic rather than steady or 

uninterrupted. EPA believes that the inclusion of such tanks is 

consistent with the intent of this exclusion, which is to preclude 

regulation of tanks that form an integral part of a production process.

Under the same rationale, EPA agrees with commenters that 

tanks that hold intermediates may be an integral part of a production 

process. Accordingly, tanks that store intermediates as part of a 

production process are flow-through process tanks. Similarly, the 

Agency agrees with the commenter who suggested that holding tanks, pulse 

tanks, feed tanks, mixing tanks, tanks that hold material being cut in 

concentration, and other tanks in the process stream are flow-through 

process tanks.

The Agency does not agree, however, that wastewater treatment 

tanks, including oil-water separators, are flow-through process tanks. 

These tanks do not form an integral part of a production process. 

Wastewater treatment tanks typically follow the production process, and 

in no way contribute to the production itself. Many of these treatment 

tanks, however, fall within the regulatory exclusion for tanks that are 

subject to CWA requirements or are excluded because they contain de

minimis concentrations of regulated substances; wastewater treatment 

tanks that are not excluded are deferred from these regulations (see 

section IV.A.3.). For the same reasons, hydraulic lifts and electrical 

equipment, which commenters suggested should be defined as flow-through 

process tanks, are not. Hydraulic lift tanks and electrical equipment 

do not form part of a production process. 

One commenter requested clarification on whether processes in 

service industries, specifically the dry cleaning industry, would 

qualify as "production processes." In the dry cleaning industry, the 

main "product," the cleaning of garments, is really a service. As 

stated above, EPA does not intend to restrict the phrase "production 

process" solely to industries where a tangible good is produced. Tanks 

that contain regulated substances that are integral to the dry cleaning 
process are eligible for consideration as flow-through process tanks. 

The tanks in dry cleaning machines, however, store regulated substances 

prior to their introduction to the cleaning process. Thus, these tanks 

are not flow-through process tanks. 

(8) Liquid Traps or Gathering Lines Related to Oil or Gas 

Production and Gathering Operations.

The eighth exclusion covers "liquid traps or associated 

gathering lines directly related to oil or gas production and gathering 

operations." The liquid trap exclusion refers to sumps, well cellars, 

and other traps used in association with oil and gas production, 

gathering, and extraction operations (including gas production plants), 

for the purpose of collecting oil, water and other liquids. Such liquid 

traps may temporarily collect liquids for subsequent disposition or 

reinjection into a production or pipeline stream, or may collect and 

separate liquids from a gas stream.

This exclusion applies only to traps and gathering lines, and 

does not include other storage tanks at oil and gas production sites. 

Similarly, although liquid traps are often used in activities other than 

oil and gas production, the only liquid traps excluded from UST 

jurisdiction under this provision are liquid traps used for the purpose 

of separating oil and gas liquids from water at oil and gas production 

facilities. Liquid traps used in conjunction with landfill methane gas 

production facilities are within this exclusion and would not be subject 

to UST jurisdiction. Liquid traps such as grease and oil traps at gas 

stations, however, are not within this exclusion.

Gathering lines are defined as any pipeline, equipment, 

facility, or building used in the transportation of oil or gas during 

oil or gas production 

or gathering operations.

Several commenters argued that EPA misinterpreted 

Congressional intent because the proposal preamble implied that this 

exclusion was limited to unused oil. The commenters suggested it should 

apply to both used and unused oil at oil and gas production sites. The 

Agency agrees with these commenters because this exemption is aimed 

generally at collection traps and gathering lines at oil and gas 

production facilities and does not distinguish between produced oil, 

used oil, or unused oil at those facilities. 

Although many petroleum pipeline facilities are regulated 

under the Hazardous Liquid Pipeline Safety Act of 1979, and thus 

excluded from Subtitle I jurisdiction, tanks associated with gathering 

lines in rural areas are statutorily exempt from Department of 

Transportation regulations. Tanks associated with rural oil and gas 

pipelines, however, are exempted as "gathering lines" under this 

exclusion. Thus, tanks associated with rural pipelines that are not 

excluded from Subtitle I jurisdiction via the exclusion for pipeline 

facilities would be subject to this exclusion.
(9) Underground Areas Exclusion. 

The ninth exclusion covers "storage tanks situated in an 

underground area (such as a basement, cellar, mine working, drift, 

shaft, or tunnel) if the storage tank is situated upon or above the 

surface of the floor."

This exclusion applies to "underground rooms" in which tanks 

are located on or above the floor surface. The purpose of this 

exclusion is to remove from UST jurisdiction tanks that are technically 

underground but that also are, in a practical sense, no different from 

aboveground tanks. They are situated so that, to the same extent as 

tanks aboveground, physical inspection for leaks is possible. Thus, the 

requirement to be able to physically inspect the tank for leaks is 

consistent with the purpose of this exclusion.

Tanks located in a below-grade structural vault, cellar, 

basement, mine or other underground room would be included in this 

exclusion if the tanks sit upon or above the surface of the floor and 

there is sufficient space to enable physical inspection of the tank, but 

not necessarily the tank bottom. An underground tank that has a 

secondary containment system that allows physical inspection of the tank 

would also qualify for this exclusion.

b. Definition of Terms Used in the Regulations

In addition to the preceding definitions of terms that 

clarify the statutory exclusions in section 9001 of Subtitle I, the 

Agency is setting forth the following definitions of terms used in the 

rule. This section today contains several terms that were not defined 

in the proposed rule. These terms have been included today in response 

to requests from commenters or to clarify other terms used in today's 

rule. These terms include cathodic protection tester, dielectric 

material, maintenance, pipe or piping, repair, and upgrading. Several 

terms that appeared in the proposed rule do not appear in this section 

of the preamble because they are no longer defined in the final rule. 

These terms are discussed (along with comment summaries and responses) 

in section IV.D. of today's preamble and include interstitial 

monitoring, inventory control, secondary barrier, and tank tightness 

testing. Also, liquid trap is now defined and discussed in the 

statutory exclusion section in IV.A.1.

Finally, several terms have not changed, did not receive 

public comments since proposal, and thus are not included here: 

electrical equipment; operational life; overfill release; positive 

sampling, test, or monitoring results; release detection; and 

underground release. Explanations of these terms are found in the 

preamble to the April 1987 proposal.
(1) Aboveground Release.

"Aboveground release" means any release to the surface of the 

land or to surface water. This includes, but is not limited to, 

releases from the aboveground portion of an underground storage tank 

system and aboveground releases associated with overfills and transfer 

operations as the regulated substance moves to or from an UST system.

Two commenters asked if the applicability of this term is 

determined by where the material escapes the UST or where it is 

eventually found. Commenters stated that a release from below the 

ground may eventually migrate to the surface, and a spill to the ground 

could infiltrate into the subsurface. The Agency has interpreted this 

term to apply to all leaks from the aboveground portion of an UST, 

including spills and overfills. The source of a leak, rather than its 

ultimate destination, is the determinant in assigning a leak to this 

category.

(2) Ancillary Equipment.

"Ancillary equipment" means any devices including, but not 

limited to, such devices as piping, fittings, flanges, valves, and 

pumps, that are used to distribute, meter, or control the flow of 

petroleum or hazardous substances to and from an underground storage 

tank.

This definition has not changed since the proposed rule. 

Some commenters asked if certain equipment, such as aboveground meters 

and pumps, was considered to be ancillary equipment, and to what extent 

such equipment would be regulated. EPA has clarified the discussion of 

ancillary equipment in the section on release detection to address the 

commenters' concerns.

(3) Belowground Release.

"Belowground release" means any release to the subsurface of 

the land and to ground water. This includes, but is not limited to, 

releases from the belowground portions of an underground storage tank 

system and belowground releases associated with overfills and transfer 

operations as the regulated substance moves to or from an underground 

storage tank.

This definition is slightly different from the proposed 

rule, which contained different definitions for this term in the 

preamble and the rule. EPA has adopted the more general definition set 

forth in the proposal preamble. The definition in the final rule has 

also been clarified by substituting the term "regulated substance" for 

"petroleum" to include all regulated UST systems.
(4) Cathodic Protection.

"Cathodic protection" is a technique to prevent corrosion 

of a metal surface by making that surface the cathode of an 

electrochemical cell. For example, a tank system can be cathodically 

protected through the application of either galvanic anodes or impressed 

current.

The phrase "for example" has been added to this definition 

since the proposed rule to emphasize that cathodic protection may be 

provided by either galvanic anodes or impressed current, but is not 

required to be one of the two. Any other technique that provides 

cathodic protection may also be used.

(5) Cathodic Protection Tester.

"Cathodic protection tester" means a person who can 

demonstrate an understanding of the principles and measurement of all 

common types of cathodic protection systems as applied to buried or 

submerged metal piping and tank systems. This person must have 

education and experience in the measurement of cathodic protection of 

buried metal piping and tank systems. This definition was also added to 

the final rule in response to comments on the qualifications necessary 

for corrosion protection test personnel and is discussed in more detail 

in section IV.C.2. of this preamble.

(6) Compatible.

"Compatible" means the ability of two or more substances to 

maintain their respective physical properties upon contact with one 

another for the design life of the tank system under conditions likely 

to be encountered in the UST.

One commenter suggested that the proposed definition, which 

based compatibility upon whether substances could maintain physical and 

chemical properties "upon contact with one another for extended periods 

of time and under varied environmental conditions (i.e., at different 

temperatures)," was ambiguous due to the phrases "extended periods of 

time" and "varied environmental conditions (i.e., at different 

temperatures)." The Agency agrees that these terms were vague and has 

replaced the phrase with "for the design life of the tank system under

conditions likely to be encountered in the UST."
(7) Corrosion Expert.

A "corrosion expert" is a person who, by reason of thorough 

knowledge of the physical sciences and the principles of engineering and 

mathematics acquired by a professional education and related practical 

experience, is qualified to engage in the practice of corrosion control 

on buried or submerged metal piping systems and metal tanks. This 

person must be accredited as being qualified by the National Association 

of Corrosion Engineers (NACE) or be a registered professional engineer 

who has certification or licensing that includes education and 

experience in corrosion control of buried or submerged metal piping 

systems and metal tanks.

As proposed, this definition required NACE certification. 

One commenter pointed out that NACE provides accreditation, not 

certification of corrosion expertise. NACE does in fact accredit and 

certify corrosion expertise. The final definition has been modified to 

take this into account. NACE also has recently introduced a 

certification program for cathodic protection specialists and cathodic 

protection testers.

Several commenters argued that the requirements for a 

corrosion expert were unnecessarily strict, and that their use would 

exclude many qualified people from work on UST systems. Many people, 

the commenters argued, did not have NACE certification or a professional 

engineering degree but were highly qualified based on their experience. 

The requirements of the definition (specifically, that a corrosion 

expert be accredited by NACE or have other types of licensing or 

certification) are not expected by EPA to exclude such qualified persons 

from work as corrosion experts unless they cannot satisfy the tests for 

accreditation. Thus, they are intended to provide some type of 

assurance to tank owners and operators, as well as implementing 

agencies, that a corrosion expert actually has achieved a minimum degree 

of expertise and experience needed to ensure corrosion is managed in a 

way that prevents leaks from UST systems and hereby protects human 

health and the environment. People who have attained the necessary 

qualifications through experience should be able to easily become NACE 

accredited.

(8) Dielectric Material.

A "dielectric material" is one that does not conduct direct 

electric current. Dielectric coatings are used to electrically isolate 

UST systems from the surrounding soils. Dielectric bushings are used to 

electrically isolate portions of the UST system (i.e., tank from 

piping). This definition was added to the final rule in response to 

comments; see section IV.B.3.b. of today's preamble for further 

discussion of this issue.
(9) Excavation Zone.

"Excavation zone" is defined as the volume containing the 

tank system and backfill material bounded by the ground surface, walls, 

and floor of the pit and trenches into which the UST system is placed at 

the time of installation.

The Agency has changed this term in the final rule from 

excavation "area" to excavation "zone" to indicate measurement in three 

dimensions.

(10) Existing Tank System.

"Existing tank system" means a tank system used to contain 

an accumulation of regulated substance or for which installation has 

commenced on or before the effective date of this regulation. 

Installation is considered to have commenced if: (1) the owner or 

operator has obtained all federal, state, and local approvals or permits 

necessary to begin physical construction of the site or installation of 

the tank system; and (2) if either: (a) a continuous on-site physical 

construction or installation program has begun, or (b) the owner or 

operator has entered into contractual obligations--which cannot be 

canceled or modified without substantial loss--for physical construction 

at the site, or installation of the tank system, to be completed within 

a reasonable time. 

Existing tanks that are converted from tanks storing nonregulated substances to tanks storing regulated substances after the 

effective date of the rules are considered "new tank systems" and are 

required to meet new tank standards. 

One commenter stated that the language in the preamble to 

the proposed rule implied that UST systems that were permanently taken 

out of service or decommissioned before the effective date of the 

regulations are "existing tank systems." Tanks that have been taken out 

of service would not meet the definition of "existing tank system" if 

they contained no regulated substances. However, the definition of 

"existing tank system" is only relevant to the determination of when 

certain requirements must be met, not which requirements apply. Certain 

regulatory requirements apply to out-of-service tanks that were used in 

the past for the storage of regulated substances. Subpart G (§ 280.70) 

addresses out-of-service tanks, and this issue is addressed in section 

IV.G. of this preamble.
(11) Free Product.

"Free product" refers to a regulated substance that is 

present as a non-aqueous-phase liquid (e.g., liquid not dissolved in 

water). 

The proposal defined free product as "regulated substance 

in the non-aqueous phase (e.g., liquid not dissolved in water) that is 

beneath the surface of the ground." One commenter suggested that this 

phrase should include a non-aqueous phase regulated substance that is on 

surface water. The Agency agrees that this is free product and has 

modified the definition accordingly. Other commenters suggested that 

EPA clarify the definition to clearly exclude vapors from this 

definition. The Agency agrees that vapors are not free product and has 

added the term 'liquid' to the definition. Another commenter suggested 

a lower thickness limit of one-eighth of an inch be used as a cutoff; 

any layer of product with thickness lower than this should not be 

considered free product. The Agency does not agree with this concept 

because in some instances very thin layers may still be retrievable. 

The regulations require that free product must be removed to the maximum 

extent practicable as a part of the total site cleanup.

Other commenters suggested that the definition be modified 

to include a field criteria for use in corrective action. The Agency 

has chosen to not include this type of criteria because determining the 

presence of free product and the extent to which it can be removed 

depends on site conditions and the technology employed. EPA believes 

that it is preferable to leave this determination to the discretion of 

the implementing agency. This issue is discussed in more detail in 

section IV.F. of this preamble.

(12) Hazardous Substance UST System.

"Hazardous substance UST system" means an UST system 

containing either (a) hazardous substances 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) or (b) any mixture of such substances and 

petroleum that is not regulated as a petroleum UST system. Thus, the 

final rule, in effect, defines a hazardous substance UST system as any 

UST system storing regulated substances which is not a petroleum UST 

system. It is essentially a catchall for any UST system for which the 

effectiveness of petroleum release detection and corrective action 

technology is uncertain. By contrast, in the proposed rule, a hazardous 

substance tank system was defined as a system containing an accumulation 

of hazardous substances or a mixture of such substances and petroleum in 

which hazardous substances comprise greater than 50 percent of the 

weight or volume of the mixture. The change from the proposed to the 

final definition eliminates the proposed 50-percent mixture rule for 

distinguishing tanks subject to the petroleum release detection 

requirements.
Many commenters agreed with the Agency's proposal in the 

Supplemental Notice that a substance not found on the petroleum list but 

listed under CERCLA should be regulated as a hazardous substance. Other 

commenters felt that if a hazardous substance was a constituent in 

petroleum, then that substance should be regulated like petroleum when 

it is stored in its pure form. Other commenters stated the converse 

argument: that because some hazardous substances are constituents in 

petroleum, then petroleum should be regulated as a hazardous substance.

The final rules distinguish petroleum and petroleum-based 

substances from other hazardous substances or mixtures for the purposes 

of determining which type of release detection requirements apply to new 

UST systems. UST systems storing petroleum, including its natural or 

refinery-added "hazardous substance" constituents (and stored materials 

with petroleum-like characteristics), are allowed to use a wide range of 

release detection methods in today's rule because petroleum has chemical 

and physical properties that make it highly detectable and amenable to a 

wide array of available corrective action technologies. A hazardous 

substance in its pure form, however, does not necessarily retain the 

same characteristics when it is a constituent in petroleum. Thus, the 

storage of such hazardous substances in new UST systems is governed by 

the release detection requirements for non-petroleum regulated 

substances, i.e., secondary containment. In the final rule, the 

determination of which type of release detection requirement is 

appropriate at an UST storing a regulated substance is not based on the 

Agency's interpretation of the definition of "petroleum" or "hazardous 

substance." (For further discussions of the differences between 

petroleum and hazardous substance USTs and their associated release 

detection requirements, see also section IV.D.2. on hazardous substance 

release detection, and section III.C.3. on alternative approaches to 

hazardous substance UST systems.)

In the proposed rule, an UST system was regulated as either 

a petroleum or hazardous substance UST system based on whether 

"petroleum" or "hazardous substances" were stored in the system. The 

problem of how to regulate a mixture of petroleum and hazardous 

substance was addressed in the proposed definitions of hazardous 

substance UST and petroleum UST by the "50-percent rule." A mixture of 

regulated substances was subject to either the petroleum UST system 

requirements or hazardous substance UST system requirements depending on 

which of these substances comprised more than 50 percent of the mixture. 

At proposal, the Agency thought this was a straightforward way to 

decide which release detection requirements for new UST systems were 

applicable to a mixture or blend of petroleum and hazardous substances. 

After proposal, however, the Agency became concerned that this approach 

would prove to be unworkable because of the difficulty of measuring 

constituent concentrations and the uncertainty of how to address 

constituents of petroleum that are also hazardous substances. In 

addition, there is not a single percentage value that is applicable to 

all mixtures and blends for determining when the substance will no 

longer be reliably detected by one of the release detection technologies 

allowed under the rule for petroleum USTs, and there is a wide variation 

in the degree of "hazardousness" among the many substances listed in 

section 101(14) of CERCLA.
For these reasons, in the Supplemental Notice, the Agency 

considered replacing the 50-percent rule with a specific list of all 

substances and blends of regulated substances that would be regulated 

under petroleum UST requirements. Any other blend or mixture of 

regulated substances would be subject to hazardous substance UST 

requirements. Many commenters supported the proposed 50-percent rule 

because it was clear and because it would be difficult to list all 

petroleum substances. Others supported the 50-percent rule approach but 

recommended alternative percent values ranging from 1 percent to 50 

percent. Many commenters, particularly state agencies, supported the 

idea of a list because it would lessen the need for determining how to 

regulate a particular stored mixture, and thereby decrease the burden on 

the implementing agencies. It was also believed to give the owner and 

operator clear guidelines in determining the status of blends and, 

therefore, which release detection method to use. These commenters said 

that any percentage method would be cumbersome and difficult to enforce 

because it would be difficult to measure concentrations in the UST 

system.

After consideration of all of these comments, EPA concluded 

that neither a percentage rule nor a comprehensive list of petroleum or 

petroleum-based substances is a practical solution to the problem of how 

to determine which blends and mixtures of regulated substances must meet 

the release detection standards for new UST systems storing hazardous 

substances. (See the discussion concerning "regulated substance" in 

section IV.A.4.a. earlier in this preamble for the reasons why the 

Agency rejected the proposed comprehensive list approach.) The main 

drawback to the percent approach is the variability of a meaningful 

value. For example, 5-percent pesticide mixed in oil or 5-percent 

pentachlorophenol mixed in mineral spirits for application purposes 

should be stored in USTs with secondary containment and interstitial 

monitoring because of the high toxicity of these substances and the 

unavailability of highly effective corrective action technologies and 

release detection. In contrast, a hazardous substance such as methanol 

that is highly flammable as a pure product can be blended in relatively 

high proportions with motor gasoline and not change the flammable nature 

of the motor gasoline. It can be safely stored in a protected singlewalled tank because release detection and corrective action technology 

are available for the petroleum-methanol mixture; and these methods are 

the same or very similar to those used for petroleum products. Thus, 

the appropriate percentage value to use in determining the release 

detection requirements that must be used at a new UST storing a mixture 

of regulated substances should be determined by the implementing agency 

based on a consideration of the following factors: the availability of 

reliable and sensitive release detection, the availability of effective 

corrective action technologies, and the inherent toxicity of the 

substance stored.
The final rule, therefore, does not contain a "50-percent 

rule" to determine how mixtures of petroleum and hazardous substances

should be regulated. Rather, the final rule lists specific substances 

subject to the petroleum UST system requirements and uses a de minimis

standard to determined when other mixtures of petroleum and hazardous 

substances are subject to petroleum UST system standards. A "petroleum 

UST system" is, thus, one which contains petroleum or petroleum and de

minimis amounts of other regulated substances. Any other UST system is 

a hazardous substance UST system and must be provided with secondary 

containment or obtain a variance. The de minimis amount of hazardous 

substance mixed with a petroleum product is that amount in which the 

additional hazardous substance does not alter the detectability, 

effectiveness of corrective action, or toxicity of the petroleum to any 

significant degree.

(13) Hydraulic Lift Tank.

"Hydraulic lift tank" means a tank holding hydraulic fluid 

for a closed-loop mechanical system that uses compressed air or 

hydraulic fluid to operate lifts, elevators, and other similar devices.

One commenter stated that the definition of this term in 

the proposal did not include elevator lifts. In response, the Agency 

changed this definition to include lifts that operate by compressed air 

or hydraulic fluid. This change properly includes all elevator lifts 

within the hydraulic lift definition.

(14) Implementing Agency.

"Implementing agency" means EPA, or, in the case of a state 

with a program approved under section 9004 (or pursuant to a memorandum 

of agreement with EPA), the designated state or local agency responsible 

for carrying out an approved UST program.

As the definition states, section 9004 empowers the Agency 

to approve a state program to operate in lieu of the federal program. 

The state agency responsible for carrying out an approved program is the 

lead implementing agency for the UST program. A state may decide to 

work through designated local agencies to carry out the approved 

program. It is important to note that the local or state agency 

responsible for the enforcement of the UST regulations, particularly 

once the state program is approved, is expected to be an owner and 

operator's first contact in any situation involving a leaking UST 

system. The state and local agencies could then contact EPA if 

necessary.
(15) Maintenance.

"Maintenance" is the normal operational upkeep to prevent 

an UST from releasing product. This definition has been added since 

proposal in response to requests by several commenters for clarification 

of this term. The comments and the use of this term are discussed 

further in section IV.C.2. of this preamble.

(16) New Tank System.

"New tank system" means a tank system that will be used to 

contain an accumulation of regulated substance and for which 

installation has commenced after the effective date of this regulation.

Existing tanks that are converted after the effective date 

of this regulation from tanks storing non-regulated substances to tanks 

storing regulated substances are considered new UST systems and are 

required to meet new tank standards.

(17) Petroleum UST System.

"Petroleum UST system" means an UST system containing 

petroleum or mixtures of petroleum with de minimis quantities of other 

regulated substances. Such systems include those containing motor 

fuels, distillate fuel oils, residual fuel oils, lubricants, petroleum 

solvents, or used oils.

In the proposed rule, a petroleum UST system was defined as 

a system that contained an accumulation of petroleum or a mixture of 

regulated substances and petroleum in which petroleum comprised greater 

than 50 percent of the weight or volume of the mixture. In the 

Supplemental Notice, the Agency proposed the development of a list of 

petroleum or petroleum-based substances subject to the petroleum UST 

system requirements. Based on public comment, however, the Agency has 

decided that it would be unworkable, time consuming, and largely 

unnecessary to specifically identify all possible petroleum products, 

petroleum-based substances, and mixtures of these substances with 

hazardous substances that should be subject to petroleum UST standards.

The definition for petroleum UST systems has been revised 

in two ways in the final regulation. The 50-percent rule for mixtures 

has been deleted and replaced with a limitation of non-petroleum 

regulated substances to de minimis levels. Use of this approach is 

intended to better determine if an UST system qualifies for the new 

petroleum UST release detection methods (see also definition of 

hazardous substance UST system). In addition, a list consisting of 

seven general categories of substances has been added to the petroleum 

UST system definition to more clearly identify the major types of 

petroleum and petroleum-based substances that may be stored in new 

protected single-walled tanks with release detection rather than only in 

UST systems that meet the secondary containment requirements. These 

categories are not substances that necessarily must be defined as 
petroleum under CERCLA, but instead are substances for which the Agency 

has determined single-walled tanks with cathodic protection and monthly 

release detection are adequate to protect human health and the 

environment. Other mixtures of regulated substances (for example, 

petroleum products mixed with non-indigenous hazardous substances or

contaminated petroleum products) will have to be considered on a caseby-case basis by the implementing agency, using the de minimis rule. 

The EPA anticipates that few blends and mixtures will present 

interpretation difficulties. See part (12) of this section for an 

explanation of the application of the de minimis rule.

(18) Pipe or Piping.

A "pipe" or "piping" is any hollow cylinder or tubular 

conduit that is constructed of non-earthen materials. This definition 

has been added since the proposed rule at the suggestion of a commenter 

(see sections IV.B.1. and IV.C.5. of this preamble for further 

discussion). 

(19) Repair.

"Repair" means to restore a tank or UST system component 

that has caused a release of product from the UST system.

This term has been added since proposal in response to 

public comments requesting additional clarification concerning the 

differences between repair, upgrading and maintenance. Refer to section 

IV.C.5. of today's preamble for further discussion of this issue.

(20) SARA.

"SARA" means the Superfund Amendments and Reauthorization 

Act of 1986.

(21) Sump.

This term has been deleted from the final rule.

Several commenters stated that this definition was 

ambiguous due to the inclusion of the term "temporarily." They 

suggested it be removed or that an actual time be substituted. The 

Agency agrees and has eliminated the definition from the final rule. 

This definition is no longer needed because the final rule no longer 

contains any requirements or provisions specific to sumps.
(22) Upgrade.

An "upgrade" is the addition or retrofit of some portion of 

an UST systems, such as cathodic protection, lining, and spill and 

overfill controls, to improve the ability of the UST to prevent the 

release of product in accordance with § 280.21.

Although this term was not defined in the proposal, it has 

been added at the recommendation of commenters. Further discussion of 

upgrading is presented in section IV.B.3. of today's preamble.

(23) UST System or Tank System.

"UST system" or "tank system" means an underground storage 

tank, connected underground piping, underground ancillary equipment, and 

containment system, if any. This definition has been changed to include 

within the UST system only underground ancillary equipment. 

Two commenters suggested that the phrase "underground 

piping" be defined to exclude any non-wetted piping such as vent lines. 

EPA does not agree with the commenters. Because such "non-wetted" 

piping can contain regulated substances, particularly when the tank is 

overfilled, EPA believes that certain requirements in this rule are 

applicable to this type of piping. Clarification has been added in 

today's rule regarding which requirements are applicable to "non-wetted" 

piping.

(24) Wastewater Treatment Tank.

"Wastewater treatment tank" means a tank that is designed 

to receive and treat an influent wastewater through physical, chemical, 

or biological methods.

This definition has been changed since the proposal so that 

it no longer includes only tanks regulated under the Clean Water Act. 

This term now refers to any tanks that are designed to treat wastewater. 

Of these, only some are regulated under the CWA. This change was 

required due to the different regulations for CWA-regulated and non-CWAregulated wastewater treatment tanks.

UST Systems: Design, Construction, Installation, and 

Notification

The following sections present major issues raised by 

public comments and new information gathered since proposal concerning 

the design, construction, installation, and notification of UST systems. 

Also, these sections discuss changes in the final rule based on these 

public comments and this new information.
1. Design and Construction Requirements (§ 280.20)

As discussed in the preamble to the April 17 proposal (52 

FR 12695), EPA concluded that national design and construction 

requirements are needed for new UST systems, especially with regard to 

corrosion protection. In discussing general approaches to design and 

construction standards, EPA concluded that industry codes of practice 

adequately address proper design. EPA invited comments on the methods 

that should be used to recognize development of future codes of practice 

that meet the intent of the requirements of the proposed rule concerning 

the design, construction, and protection from corrosion of UST systems. 

Many comments were received by EPA on this issue.

Many commenters suggested that EPA set detailed design 

standards in the final rule. Some new or alternate methods for tank 

design, fabrication, or protection techniques were suggested. For 

example, a few commenters suggested that concrete tanks should be more 

explicitly allowed. One suggested adding unbonded polyethylene wrap as 

an option for corrosion protection. EPA still believes, however, that 

the general approach taken at proposal of relying on industry codes of 

practice, rather than specifying detailed regulatory standards, is more 

appropriate because this approach allows new and effective technologies 

to be developed and put into use.

In today's final rule, EPA simply requires that all new 

tanks be designed and manufactured according to standards of a 

nationally recognized organization or an independent testing laboratory. 

These requirements also allow the use of concrete or stainless steel 

tanks if the implementing agency determines that the design, 

construction method, and corrosion protection system would prevent the 

release of any stored regulated substances in a manner that is no less 

protective of human health and environment than tanks allowed by the 

requirements of § 280.20(a)(1)-(4). Specific design and construction 

issues are discussed in detail below.
a. Tank Requirements (§ 280.20(a))

(1) Fabrication.

As discussed in the preamble to the April 17 proposal (52 

FR 12696), EPA proposed to require one of three fabrication techniques 

for tanks: fiberglass-reinforced plastic (FRP), coated and cathodically 

protected steel, and steel-fiberglass-reinforced plastic composite. The 

allowed fabrication techniques were chosen to provide protection of 

buried structures from galvanic corrosion by using either a cathodic 

protection system or noncorrodible materials. Although comments were 

submitted suggesting flaws in each of the UST types listed in the 

proposal, the data submitted indicate excellent performance of all these 

protected tanks. Recent studies sponsored by EPA have yet to identify a 

documented case of failure by corrosion of these protected, "new 

generation" tanks having in-service ages of up to 30 years. Therefore, 

today's rule is unchanged with respect to these new tank fabrication 

requirements.

Information obtained by the Agency since proposal on 

performance of each of the three fabrication techniques specifically 

allowed in the final rule is briefly summarized below. Additional 

discussion is presented earlier in the Causes of UST Releases section of 

today's preamble.

FRP Tanks. Nearly 200,000 FRP tanks have been installed 

nationwide, with some as old as 22 years old. There were some failures 

of these tanks when first introduced; however, modification of 

installation practices and tank design has reduced the annual failure 

rate to less than 0.05 percent. If the tank fails, failure usually 

occurs soon after installation and is due to improper installation.

Coated and Cathodically Protected Tanks. Approximately 

100,000 of these tanks have been installed at UST sites. Though some of 

the tanks are over 20 years old, the majority have been installed within 

the last 5 years. There have been very few failures of these systems to 

date. None of the failures have resulted in a warranty claim. The few 

failures that did occur were due either to improper installation 

practices or to not following monitoring procedures correctly. Cathodic 

protection technology has been widely applied to pipelines and other 

buried metal structures for over 30 years. A dramatic reduction in 

failures has resulted from the use of cathodic protection on pipelines.

Composite Tanks. This tank type is not as popular in this 

country as the other types of protected tanks, but has been widely used 

in Europe. Approximately 65,000 composite tanks have been installed in 

the U.S. and have been in use for about 25 years without a single 

reported corrosion-related failure. The current manufacturing standards 

for these tanks are much more stringent than they were in the past. 

Even though there is not as much historical performance data on 

composite tanks as there is for FRP or coated and cathodically protected 

tanks, EPA has confidence in their future performance because of the 
fault-free performance of the older tanks of this type and the more 

stringent manufacturing standards that are now in use.

(2) Corrosion Protection.

Corrosion Experts. EPA proposed in § 280.20(a) that fieldinstalled cathodic protection systems should be designed by an 

independent corrosion expert. The Agency requested comments on the 

merits of this approach, and several comments were received by EPA on 

this issue. Most of the comments strongly opposed the requirement of an 

"independent" corrosion expert because they felt that this requirement 

would place an unnecessary financial burden on owners. In addition, 

they pointed out that the term "independent" should not be required 

because very few independent corrosion experts are available. Some 

suggested that the term "independent" should be replaced with 

"certified" or "qualified." Others suggested the use of "in-house" 

expert because an "in-house" corrosion expert would have better working 

knowledge of the systems to be protected, condition of use, and the 

surrounding environmental condition.

Although no clear evidence was submitted to indicate that 

corrosion protection systems that are designed by independent experts 

would perform better or worse than systems designed by non-independent 

experts, information obtained from public comments indicates that 

relatively few independent corrosion experts are available to fulfill

the large demand for system designs. In the final rule, EPA has, 

therefore, deleted the requirement that the corrosion expert must be 

independent. Thus, the use of in-house personnel is acceptable provided 

that they meet the definition of "corrosion expert."

Composite Tanks. In the preamble to the proposal (52 FR 

12698), EPA invited comments, standards, and documented performance data 

for FRP-steel composite tanks (also called "clad" tanks). Several 

comments were received by EPA on the issue of whether or not cathodic 

protection is needed for composite tanks.

EPA believes that cathodic protection for this type of tank 

is not needed because the exterior of the steel tank is bonded to a 

thick fiberglass shell that has inherent corrosion resistance 

properties. EPA was unable to identify one case where this type of tank 

has failed due to corrosion and also noted that one major manufacturer 

of this type of tank recently began to offer lifetime guarantees from 

failure for its tanks. Thus, in the final rule, EPA has retained the

provision that, as long as these tanks are designed and manufactured 

according to a recognized national standard of practice, FRP-steel 

composite tanks do not require cathodic protection.

At proposal, industry codes for composite tanks were still 

in draft form. Commenters suggested that composite tanks should be 

excluded from the final rule until UL 1746 is final. EPA disagrees with 

this comment because manufacturers are now being approved under this 

standard in its draft form. 
Moreover, EPA has amended the rule to reference a new industry consensus 

design standard, ACT-100, "for the fabrication of FRP clad or composite 

underground storage tanks" submitted by a commenter. Accordingly, EPA 

has concluded that it is unwarranted to delay allowing the use of 

composite tanks given their outstanding performance to date and the 

availability of the ACT-100 design standard and the draft UL 1746 

performance standard. 

No 12,000 ohm/cm Exclusion. As discussed in the preamble 

to the April 17, 1987, proposal (52 FR 12698), EPA had proposed dropping 

the 12,000 ohm/cm exclusion for underground tanks contained in the 

Interim Prohibition (see section 9003(g)(2) of RCRA). As stated in the 

proposal, this measurement alone does not adequately define a soil's 

propensity to corrode. Soil resistivity varies with depth and moisture 

content, and corrosivity has been demonstrated in soil with a 30,000 

ohm/cm reading. 

Many comments were received by EPA on this issue. Some 

requested that EPA retain the 12,000 ohm/cm exclusion in the final rule. 

Others agreed with the proposed approach stating there is no technical 

basis to establish a single number by which the corrosivity of all soils 

can be measured. EPA continues to believe that use of a single 

resistivity variable is inadequate to measure the propensity to corrode. 

Therefore, EPA has decided not to include the 12,000 ohm/cm exclusion 

in the final rule.

Some commenters suggested that there are situations where 

the surrounding soils are not corrosive and requested that a mechanism 

for relief from the corrosion protection requirements be provided for 

those situations; for example, a soil that is uniform and very dry (low 

moisture content), where the ground-water table continuously stays 

several feet below the bottom of the UST installation, and the area 

above the installation is paved to prevent percolation of rainfall and 

runoff. EPA agrees with these commenters and is including 

§ 281.20(a)(4), which allows an exemption for metal tanks from the 

requirement that all UST systems be corrosion protected provided that a 

corrosion expert determines that the site is not corrosive enough to 

cause a release during the tank's operating life. In addition, owners 

and operators must retain records of this determination for the 

operational life of the tank. These records should include evidence of 

the corrosion expert's qualifications and the results of the site 

assessment.

Alternative Designs. In the proposed rule (§ 

280.20(a)(4)), other tank designs are allowed if the implementing agency 

determines them to be no less protective of human health and the 

environment. In response to the proposal, commenters requested approval 

for several types of tanks including those constructed of concrete, 

stainless steel, and steel encased in polyethylene. Several other 

commenters reported to the Agency other potentially useful designs such 

as nylon tanks.

As a result of these comments, EPA sought information on 

several of these alternative designs and continues to believe that, with 
certain materials of construction and under certain site-specific soil 

conditions, alternative systems can be designed that will adequately 

protect human health and the environment. In addition, EPA is aware of 

new design techniques being researched that appear promising but are not 

commercially available. The Agency does not desire to restrict or 

eliminate emerging technologies and recognizes the numerous sitespecific factors that may allow for the use of alternative designs. 

Therefore, today's rule continues to provide that the implementing 

agency may approve alternatives that are no less protective of human 

health and the environment than the specified designs.

The Agency has not, however, added any of these alternative 

designs to the designs specifically allowed by the regulation because 

there is not enough documented history about the performance of these 

systems or industry consensus codes governing their fabrication and use. 

One system, for example, consists of a steel tank surrounded by a 

thick, high-density polyethylene "jacket." The "jacket" is intended to 

provide both corrosion protection and secondary containment. It has 

been reported to EPA that over 1,000 of these tanks have been installed. 

Some local and state implementing agencies have been approving this 

design. Sometimes, specific monitoring or demonstrations have been 

required to ensure that the design provides protection equal to that 

provided by the other types of protected tanks. It has also been 

reported that several manufacturers of this type of tank have begun the 

process of working with independent testing laboratories toward 

developing testing and evaluation methods for steel tanks encased in 

noncorrodible secondary containment structures. This process may take 

several years to complete however. The Agency does not wish to unduly 

restrict the use of this type of product in the interim and recognizes 

that the manufacturers need to have continued product sales to be able 

to fund the needed development and testing of these evaluation methods. 

Thus, EPA views the type of approval allowed under § 280.20(a)(4) as 

essential to the continued development of such new tank systems. For 

example, the long-term performance of a system is difficult to establish 

in the absence of allowing actual installations in the field. 

Accordingly, the final rule preserves the proposal's allowance of the 

use of alternative new designs as long as they are approved by 

implementing agencies to adequately protect human health and the 

environment.

Implementing agency approval of alternative new tank 

designs, or special designs for specific sites, will only be provided if 

the UST system is determined to be no less protective of human health 

and the environment than the other types of tanks already listed in 

today's rule. Accordingly, an alternative design must meet the two 

basic criteria that all of the other methods meet: (1) it must be 

designed and constructed to prevent releases due to structural failure 

for the operating life of the system, and (2) it must be designed to 

prevent releases due to corrosion for its operating life. For example, 

the "jacketed" tanks described earlier obviously meet the structural 

criteria because each inner steel tank is built to the U.L. 58 standard. 

These types of tanks are also designed to prevent releases due to 

corrosion because the secondary containment jacket isolates the steel 

tank from the surrounding soil. However, in the absence of an existing 
consensus code applicable to the jacket, or a long-term performance 

record, it is difficult to determine if releases due to corrosion will 

be prevented for the tanks' operating life. Thus, the implementing 

agency could allow the use of this type of tank if a national consensus 

code is eventually developed for the jacket or this outer jacket is 

determined to be free of holes at least as frequently as cathodically 

protected tanks are checked (after installation and every 3 years 

thereafter). The integrity of this outer jacket can be ensured in 

several ways, including several methods of interstitial monitoring or 

the periodic performance of a tank structure-to-soil potential 

measurement by a cathodic protection tester.

b. Piping Requirements (§ 280.20(b))

The proposed rule (52 FR 12698) required the same corrosion 

protection for piping systems as used for the underground storage tank 

itself. Two types of protection systems were allowed: fiberglass 

piping, or coated and cathodically protected steel piping. The same as 

for the tanks, provisions for approval of alternative piping methods 

were also proposed. Today's rule remains largely as proposed, although 

the requirement for an "independent corrosion expert" has been revised 

to delete the requirement for independence, and an option for approval 

of alternative designs by a corrosion expert has been added. These 

issues are discussed below. In addition, the extent of corrosion 

protection of components and possible alternate materials of 

construction were highlighted as issues in the proposal for public 

comment and are discussed in detail below.

(1) Independent Corrosion Expert.

EPA proposed in § 280.20(b) that steel piping coated and 

cathodically protected with a field-installed cathodic protection system 

must be designed by an independent corrosion expert. The Agency 

requested comments on the merits of this approach. Several comments 

were received by EPA regarding the need for an independent corrosion 

expert concerning the protection of steel tanks. (See section 

IV.B.1.a.(2). for a discussion of this issue.) In response to these 

comments, EPA has removed the requirement that the corrosion expert must 

be independent.
(2) Corrosion Protection of Tank System Components.

The Agency invited comments on which tank components, if 

any, should be cathodically protected and, if cathodic protection is not 

required, what form of corrosion protection is appropriate. Several 

comments were received by EPA on this issue. Some suggested that EPA 

should require cathodic protection on FRP-steel composite tanks as well 

as any steel fittings on FRP tanks. Some suggested that all metallic 

components of the UST system, including metallic connectors, swing 

joints, flexible connectors, and riser connections should be coated or 

cathodically protected. Other commenters suggested that cathodic 

protection on steel fittings on FRP tanks is unnecessary and that 

components like bung hole plugs and pump housings do not need cathodic 

protection.

EPA agrees with the commenters who stated that cathodic 

protection of tank fittings is not needed because these components are 

located at the top of the tank and rarely contact the stored product. 

Section 280.20(a) of the final rule has been modified to restrict the 

applicability of the corrosion protection requirements to "any portion 

underground that routinely contains product."

EPA's causes of release study indicates that the 

operational piping portion of UST systems is twice as likely as the tank 

portion to be the source of the release. Piping failures are caused 

equally by poor workmanship and corrosion. Threaded metal areas made 

active by threading have a high propensity to corrode if not coated and 

cathodically protected. Today's rule specifically requires the 

corrosion protection of operational underground piping and components 

that are in contact with the soil and convey product to or from the tank 

(e.g., flexible connectors, swing joints, pipe fittings, and impact 

valves), whether in metallic or FRP piping runs. Nonoperational 

components, such as vent and vapor recovery lines, on the other hand, 

need not have corrosion protection because these components should never 

contain free liquid product, particularly under today's requirements for 

overfill prevention (see § 280.30). Metallic components, such as swing 

joints, do not need cathodic protection if they are placed in pump 

housings and are not in contact with the ground.

The Agency also invited suggestions on the use of pipes 

other than FRP and corrosion-protected steel pipe. One commenter 

suggested use of copper tubing. Today's rule allows copper tubing under 

two circumstances. First, copper piping would be allowed if a corrosion 

expert determines that the site is not corrosive enough to result in a 

release during the operational life of the piping. Second, copper 

piping would be allowed if the design and construction methods and 

corrosion protection are determined by the implementing agency to 

prevent the release of any stored substances in a manner no less 

protective of human health and the environment than the requirements in 

§ 280.20(b)(1), (2) and (3).
c. Spill and Overfill Control (§ 280.20(c))

Design and construction requirements for new UST systems 

include spill and overfill equipment requirements. These additional 

requirements are discussed below in section IV.C.1., "Spill and Overfill 

Control." 

d. Other Issues

(1) Internal Corrosion.

In the preamble to the April 17 proposal (52 FR 12699), EPA 

solicited comments on whether internal corrosion could become a major 

source of failure. EPA requested comments based on the industry's field 

experiences with internal corrosion protection systems in terms of 

design, installation, efficacy of performance, and problems found. EPA 

also requested information on the need for internal corrosion protection 

and whether it should be required, particularly for all new steel UST 

systems.

The Agency has received several comments on this issue. 

Many expressed the opinion that internal corrosion is one of the causes 

of tank leaks. Some suggested mandating internal tank lining to reduce 

or to eliminate internal corrosion and thereby prevent leaks. Some 

suggested that EPA require the use of striker plates below fill and 

gauge fittings. A few suggested requiring the use of soft-tipped 

inventory dipsticks. Some commenters took the position that internal 

corrosion is not a problem and should not be regulated.

EPA agrees with the commenters who argued that tank lining 

will reduce the incidence of failures resulting from internal corrosion. 

The Agency is not, however, mandating the requirement of tank lining on 

new tanks because it it has concluded that striker plates, now required 

under the consensus codes, solve the problem. At present, evidence is 

limited concerning the potential of internal corrosion to cause newly 

constructed tanks to fail. Estimates of the incidence of internal 

corrosion-induced tank failures range from 5 to 60 percent of the total 

steel tank population. Several tank lining companies submitted data 

that indicate internal corrosion is a significant cause of release. By 

contrast, internal corrosion was not found to be a significant cause of 

release in an EPA-sponsored study of over 400 tank closures carefully 

investigated by Suffolk County, New York, health department officials. 

The results of this study and other information lead the Agency to 

believe that the incidence of steel tank failures due to internal 

corrosion is probably less than 10 percent of the total tank universe, 

that it occurs most often in smaller tanks, and that it takes place 

later in the operational life of these tank systems. The few cases of 

internal corrosion holes that were witnessed in this study appeared to 

be generally located at the bottom of the tank fill pipe opening and 

often could have been prevented if striker plates had b een used. These 

findings are corroborated by numerous tank manufacturers who submitted 

comments on the proposal, citing their collective experiences that 
internal corrosion is not a problem on tanks equipped with striker 

plates. Many of them suggested that the use of striker plates below the 

fill and gauge fittings will protect the primary location where internal 

corrosion occasionally breaks through.

EPA agrees with the commenters who believe that striker 

plates can largely eliminate the internal corrosion problem. The final 

rule, however, does in effect, require the use of striker plates because 

they are standard on new steel tanks and included in the referenced 

codes of practice developed by nationally recognized associations or 

independent testing laboratories. The Agency agrees with commenters who 

suggested that the use of soft-tipped dipsticks will also reduce 

internal corrosion. The final rule does not, however, include this 

alternative because it is not needed with striker plates now standard on 

all tanks.

(2) Manways.

The Agency requested comments and information about the 

required use of manways on top of new tanks and whether traditional 

"bunghole" systems of tank entry would result in a significant reduction 

in releases. Several comments were received by EPA on this issue. 

Commenters were divided on the requirements of manways. Some of them 

felt that manways do not reduce the number of leaks, but may instead add 

another potential source of release. Some felt that the requirement of 

manways is necessary because a number of costly release investigations 

can be avoided by manual inspection from inside a tank. A few 

commenters supported manways but felt that their use should not be 

mandated. 

EPA agrees with the commenters who recommended manways as a 

sound practice but believed they should not be required in the final 

rule. Although manways facilitate the manual inspection of the interior 

of a tank, other forms of release detection make internal inspections 

and, thus, the use of manways unnecessary (see discussion in section 

IV.B.2.g.(2). concerning internal inspections and release detection).
2. Installation (§§ 280.20(d) and (e))

a. Overview

As was discussed in the preamble to the April 17 proposal 

(52 FR 12700-12702), improper installation is often a cause of release 

from various components of the UST system. The public comments on the 

original proposal and on the Supplemental Notice (December 23, 1987) 

have reinforced the belief that proper installation is critical to 

preventing releases from the UST system. The new causes of release 

information obtained by the Agency since proposal (which is discussed in 

section II.F.2. of this preamble) indicates that improper installation 

is one of the major causes of underground storage tank and piping 

failures. Additionally, the majority of industry experts felt that 

improper installation causes many of the piping failures. Though the 

reported failure rates of FRP and protected-steel tanks are very low, 

failures that have occurred are usually related to improper 

installation.

Some of the installation practices that have been 

identified as leading to UST system releases include: non-homogeneous 

backfill, which is often cited as causing localized corrosion of 

unprotected steel tank system components; improper selection and 

placement of backfill, which leads to structural failure in FRP tanks; 

loose fitting in the bungs and vent lines, which leak when the tank is 

overfilled; and improper layout, fabrication, and installation (backfill 

placement and inadequate cover) of the delivery piping, which can lead 

to loose or broken pipe and fittings.

The proposed rule addressed these installation problems in 

§ 280.20(c) and (d). Section 280.20(c) listed the specific requirements 

for conducting a proper installation. Section 280.20(d) required owners 

and operators to indicate on the notification form how proper 

installation was ensured. The comments and revisions for the final rule 

on both of these sections are discussed in more detail below.

b. Installation Practices

EPA proposed in § 280.20(c) that all tanks and piping be 

installed in accordance with the manufacturer's instructions and nine 

specific requirements that were based on the major installation steps 

outlined in two industry codes: Petroleum Equipment Institute RP100-86 

and American Petroleum Institute 1615. The Agency requested comment on 

this approach, in particular the use of a final system test, after 

backfill is placed around the storage system but before it is placed 

into operation, to ensure proper installation.

Comments were received that supported the proposed 

approach. Many commenters, however, suggested refinements or exceptions 

to several of the nine specific requirements. In addition, the industry 

consensus codes from which the nine requirements were derived have been 
revised and reissued since the proposal. These two codes are now in 

substantial agreement, and their recommended practices are reported to 

be widely used by installers. One of the reasons that the Agency 

included the nine specific installation provisions in the proposal was 

to emphasize certain important basic points already set forth in the 

national consensus codes.

EPA now believes that the recently revised codes addressing 

proper installation practices are even closer in representing a national 

consensus and provide appropriate guidance for proper installation. The 

nine specific requirements have, therefore, been deleted from the final 

rule as unnecessary and are replaced with a more general performance 

standard (in § 280.20(d) and (e)) that simply requires that owners and 

operators ensure that the UST systems are installed in accordance with 

nationally accepted codes of practice and the manufacturers' 

instructions (if any).

An example of an installation practice that requires the 

consideration of both the national consensus codes and the 

manufacturer's instructions is the joining of FRP piping to metallic 

components. The consensus codes provide general guidance concerning 

where and how to make such joints, but the two major FRP piping 

manufacturers provide specific instructions concerning the details of 

fabricating this type of joint.

c. Ensuring Proper Installation

EPA proposed in § 280.20(d) that owners and operators 

indicate from a list of methods on the proposed notification form which 

method they used to ensure proper installation. Also, proposed 

§ 280.20(d) required that owners and operators obtain the installer's 

signature certifying which method was used to ensure proper 

installation. EPA requested comment on the advisability of requiring 

owners and operators to use one or more of these methods and the 

relative merits of each method.

In general, all comments supported EPA's contention that 

requirements for ensuring proper installation are warranted. Each 

approach that EPA had identified to ensure proper installation was 

favored by at least one commenter. No data were submitted to EPA in 

response to the proposal that showed any of these methods to be 

unworkable, ineffective, or preferred over all the others. Therefore, 

all but one of them have been retained in today's final rule, and they 

have been renumbered as § 280.20(e).

The one method that has been deleted from the final rule 

was the testing for leaks during and after installation. This method 

was deleted because all national consensus codes for installation 

require such testing during and after installation and thus this testing

is part of proper installation under 280.20(d), and not an optional 

method of certification as required under 280.20(e).
Other methods of ensuring proper installation were 

suggested by commenters. The first suggestion was to certify owners. 

Although the certification of owners could improve installation 

practices, the Agency is concerned that the implementation of an 

education and testing program of this magnitude would be very difficult 

to accomplish and not likely to be very effective, because owners do not 

usually install their own tanks. Some commenters suggested that EPA 

develop a national installer certification 
program. EPA believes, however, that implementing such a program at the 

national level, particularly given the large number of installers 

necessary, would be unworkable and would delay implementation of this 

rule. Also, the fact that proper installation can be effectively 

ensured by a variety of approaches makes a national program for 

certification of installers unnecessary. EPA believes that state and 

local governments are in a much better position to develop such programs 

as they deem necessary.

Some commenters suggested requiring certification of 

installers by a professional organization. EPA is not aware, however, 

of any professional association that is in a position currently to 

certify the large number of installers expected to be needed in the 

following years and, therefore, has not required such certification in 

the final rule.

Section 280.20(e) of the final rule requires owners and 

operators to indicate on the notification form which method for ensuring 

proper installation was used. Although EPA believes that the use of one 

or more of the methods allowed (i.e., manufacturer or implementing 

agency certification of the installer; inspection of the installation by 

a professional engineer or the implemental agency; completion of 

manufacturers installation checklist; or another method as approved by 

the implementing agency) will improve installation practices, today's 

allowance of a variety of methods will give owners, operators, and 

implementing agencies flexibility to choose the most appropriate 

methods.

EPA has also retained the requirement in the final rule 

that owners and operators obtain the installer's certification that the 

installation was properly performed. Thus, § 280.22(f) of the final 

Notification Requirements requires owners and operators to have the 

installer certify on the notification form that the UST system was 

installed in accordance with the performance standards of § 280.20(d). 

A signature block is provided on the notification form for the 

installer. EPA intends that owners and operators will obtain the 

signature of the person primarily responsible for the installation of 

the tank and piping system. In cases where the owner functions as the 

general contractor, hiring several parties to conduct the tank and 

piping installation, then the owner could be considered the installer.

In the proposal preamble, comments were requested on the 

advisability of requiring a site plan and, if it were required, what 

level of detail was necessary. Most commenters favored the requirement 

for a site plan but differed on the level of detail required for the 

plan. Some commenters favored a simple sketch and others favored an 

engineering drawing that would locate the tanks and the piping, indicate 

the sizes and routing of the piping, and indicate the location of 

structures on the site. Information obtained from the "Causes of 

Release Study" (see section II.F.2. of today's preamble) indicates that 

site plans are prepared voluntarily by most major corporations and are 

required in some jurisdictions when applying for building permits.
The Agency has determined that it will not make site plans 

a required record because it is not necessary to ensure compliance with 

the technical requirements promulgated today. A site plan is, however, 

a useful tool for owners and operators. The Agency notes that site 

plans are recommended in recent updates of national codes addressed to 

the installation of new UST systems.

3. Upgrading of Existing Systems (§ 280.21)

EPA proposed in § 280.21(a) that, within 10 years after the 

effective date of the final rule, all existing UST systems comply with 

the requirements for new UST systems under § 280.20 and have a fieldinstalled cathodic protection system designed by an independent 

corrosion expert. If these requirements could not be met, these UST 

systems would have to be closed. The Agency requested comments on these 

proposed requirements and the need for upgrading UST systems to prevent 

releases (see 52 FR 12702-12705).

a. Mandatory Upgrading Schedule

(1) Overview.

EPA concluded in the proposal (52 FR 12702-12704) that the 

universe of 1.4 to 2 million existing UST systems presents a significant 

threat to the public health and environment from product releases due to 

spills, overfills, and corrosion of unprotected steel tank systems. 

Presently, the majority of existing UST systems are not equipped with 

any of the release prevention or detection features that were proposed. 

The Agency also concluded that if these existing systems were 

retrofitted with safeguards proposed for new UST systems, a significant 

number of product releases could be prevented or minimized.

EPA proposed two different schedules for implementing UST 

system upgrades: one for installation of release prevention (corrosion 

protection and spill/overfill controls), and another for release 

detection. 

oCorrosion protection (which would consist of cathodic 

protection for bare steel tanks, for example), and spill 

and overfill controls were proposed to be installed at all 

existing UST systems within 10 years (see 52 FR 12774 and 

12779). 

oRelease detection at unprotected and protected existing UST 

systems was proposed to be phased in at 3 and 5 years, 

respectively, with monthly release detection monitoring 

proposed for all UST systems after 10 years.

oUST systems that could not implement a reliable and effective 

release detection method, or that did not meet upgrade 

requirements for corrosion protection and spill and 

overfill controls, within the required time frames proposed 
were to be replaced (to meet new tank standards) or 

permanently closed.

The proposed implementation schedule for release detection 

has been changed in the final rule to require existing UST systems to 

phase in release detection based on age over the first 5 years after the 

rule's effective date. (Further discussion about the Agency's rationale 

for changing this proposed requirement is presented in section IV.D.3. 

of today's preamble.) In today's final rule, the Agency has retained 

the proposed requirement that all substandard existing UST systems be 

closed, replaced, or retrofitted with corrosion protection and spill and 

overfill control equipment within 10 years after the rule's effective 

date. The final requirements concerning the upgrade of corrosion 

protection and spill and overfill controls (indicating public comments 

on this issue) are discussed below. The schedule issues are discussed 

first, followed by the upgrading methods.

(2) Approaches to Today's Rule.

During development of the proposed rule, the Agency 

considered several approaches and requirements for scheduling upgrade 

and replacement of existing substandard UST systems, including: rapid 

upgrade and replacement (e.g., within 3 to 5 years), gradual upgrade and 

replacement (within 6 to 12 years), and no required upgrade and 

replacement of existing UST systems. EPA selected the gradual approach, 

proposing that all existing UST systems storing regulated substances be 

required to either upgrade to new tank standards within 10 years 

(through retrofitting or replacement) or be permanently closed.

Many commenters, including several segments of the UST 

service industry, supported the 10-year upgrade period, believing that 

this is a reasonable time frame to allow their industry to respond to 

the large universe of existing tanks that will need to be upgraded, 

replaced, or closed. As discussed in the preamble to the proposal (52 

FR 12704), one important advantage of this approach is that it appears 

to complement current industry trends towards upgrading or replacing 

voluntarily, while setting a clear target date by which all upgrades and 

replacements must be completed. This approach provides flexibility to 

implementing agencies by allowing them to choose from numerous 

alternative phase-in approaches (e.g., based on tank age, tank type, or 

environmental vulnerability of the site) the most appropriate and 

applicable method to achieve an orderly transition in meeting the 10-

year compliance deadline. In summary, both EPA and many commenters 

believe that the proposed 10-year compliance period will provide time 

that is adequate to implement the required improvements at the 1.4 to 2 

million UST systems nationwide.

Other commenters stated that the 10-year mandatory upgrade 

period is too ambitious and should be relaxed (or lengthened) for those 

owners and operators with multiple tanks, with financial limitations, or 

in states where upgrade/ replacement programs have already been 

implemented. EPA continues to remain unconvinced, however, that 

extending the proposed compliance period will significantly lessen the 

burden on multiple tank owners or on owners and operators with limited 
financial resources because if bare steel tanks are allowed to continue 

operation after 10 years, many will eventually leak and require 

corrective action that is much more burdensome than upgrading. EPA also 

expects that most UST owners and operators will make the decision to 

upgrade or replace existing UST systems within 10 years anyway (see 52 

FR 12671). For example, many owners and operators will choose to 

conduct their upgrades prior to implementation of release detection 

(within the first 5 years) because it is more cost effective and 

practical to implement all required upgrades at a site at the same time, 

before the tank system leaks.

Many owners and operators are currently upgrading or 

replacing their existing UST systems in response to pressures other than 

federal regulatory requirements (for example, voluntary upgrading 

programs, insurance and liability concerns, and state and local 

upgrading requirements). For this reason, some commenters suggested 

that the 10-year mandatory upgrade requirement is unnecessary and should 

be deleted from the regulations. The Agency agrees that these positive 

upgrading and replacement trends will probably continue over the next 

several years, even without a regulatory requirement. EPA is concerned, 

however, that reliance only on these voluntary activities, without the 

added incentive of a regulatory deadline, will result in a significant 

number of UST systems not being upgraded or replaced over the next 10 

years. EPA has concluded that this is a situation that would not 

protect human health and the environment nationwide.

Some commenters supported a phase-in period that is more 

rapid than the proposed 10 years because the longer it takes to upgrade, 

the more releases to the environment that will occur, posing additional 

risk to the public health and environment. More than half of all 

existing UST systems are over 10 years old and constructed of 

unprotected, bare steel without any spill and overfill prevention 

equipment. EPA's information on causes of release (see earlier 

discussion on causes of release) confirms that these tank systems are 

the most likely to have releases due to corrosion, piping failures, and 

spills and overfills. Therefore, the Agency recognizes that a more 

rapid upgrade schedule will, at least theoretically, prevent a 

significant number of release incidences that may occur at existing 

substandard UST systems.

Other information obtained by the Agency during development 

of the proposal (see 52 FR 12704), however, indicated that not even the 

most aggressive state, local, or industry UST programs have required 

upgrading or replacement in as short a time frame as 3 to 5 years 

because it is universally accepted as unimplementable given the nature 

and size of the regulated community. The Agency believes that a 

mandatory, rapid upgrading approach could not be successfully 

implemented because a large portion of the regulated community consists 

of small businesses that, if faced with a shorter deadline, would 

continue their substandard operations resulting in widespread 

noncompliance. Thus, while a shorter upgrade period appears 

theoretically advantageous in terms of the environmental and health 

risks avoided, EPA has concluded that it is unlikely to genuinely 

achieve more protection of the public health and environment than the 
proposed approach because it is unimplementable by significant portions 

of this regulated community.

Many commenters (those supporting the proposed 10-year 

mandatory upgrade period, as well as the other approaches) recommended 

that UST system upgrades and replacements be phased in using a staggered 

approach over the upgrading period. They believe that this would lessen 

the burden on the UST service industry by preventing numerous owners

from waiting until the end of the 10-year compliance period to complete 

their upgrades or replacements. Tank age was the factor most frequently 

suggested as the basis for phase-in of UST system upgrades because of 

the belief that older UST systems have the greatest probability of 

leaking due to corrosion. Others suggested that the corrosive nature of 

a site, the presence or absence of corrosion protection, or the 

environmental vulnerability of an area should be used as the basis for 

determining the upgrade schedule.

Given the enormous size of the existing UST system universe 

and the practical implementation difficulties that owners and operators 

face as they upgrade necessary improvements to prevent future releases, 

EPA agrees that the implementation of the upgrade/replacement 

requirements should be phased in. The Agency decided, however, not to 

require the phase-in of UST system upgrades or replacements based on 

tank age or any other factor in the final rule for several reasons. 

First, EPA believes that numerous UST systems will be upgraded or closed 

over the next 10 years even in the absence of any federal deadline in 

the regulations. Upgrading programs are already well underway in 

numerous companies, and more are expected to begin nationwide in 

response to these regulations. As discussed earlier in the background 

section of this preamble, numerous system closures will also occur 

because of this new regulatory program. Thus, EPA has concluded that 

only a portion of the existing UST system owners and operators are 

likely to wait until the end of 10-year compliance period to complete 

their upgrades or replacements. Second, upgrading or replacement 

represents a significant undertaking for UST system owners and operators 

and the Agency has identified many appropriate factors (including, for 

example, tank age, site location, and other business-related reasons) 

already being successfully used by owners and operators to schedule 

replacements/upgrades. In an attempt to stimulate scheduled actions and 

company programs in this area, the Agency does not want to artificially 

restrict them to phase-in programs based on age. Third, the Agency has 

concluded that a simple deadline provides a clear national goal, and 

that this is all that is necessary to prompt the required 

upgrading/replacement actions over the 10-year period. Finally, today's 

approach of a 10-year deadline provides implementing agencies with the 

freedom to decide whether state or local UST programs should have a 

scheduled phase-in period and, if so, the methods they will use to do 

it.

Finally, some commenters recommended that EPA provide 

variance procedures in the final rule that would enable the avoidance 

(or delay) of implementation of the upgrading requirements for owners 

and operators who show reasonable progress in upgrading, for those 

lacking financial resources to upgrade, for protected tanks installed 
prior to final rule promulgation, and for states where UST upgrade 

programs have already been implemented. The use of such variances in 

the final rule was rejected, however, because the Agency believes that 

where upgrading has been allowed to be phased-in over 10 years, there is 

no justification for further delay in bringing substandard systems into 

compliance with requirements necessary to ensure protection of human 

health and the environment.

b. Tank Upgrading Methods for Corrosion Protection (§ 280.21(b))

Today's final rule allows three methods of tank upgrading 

for corrosion protection, as suggested by a number of commenters. EPA 

believes that each of the upgrading methods described below has been 

demonstrated to be protective of human health and the environment.

(1) Interior Lining.

The first of the options for upgrading a tank is to 

internally line the tank in accordance with the tank repair provisions 

of § 280.33. To use this technique as as the sole method for meeting 

the corrosion protection upgrade, the tank must be internally inspected 

after 10 years and every 5 years thereafter. The inspection must be 

conducted in accordance with a code of practice developed by a 

nationally recognized association or independent testing lab to ensure 

that the lined tank is performing adequately. Interior lining used as 

the sole method for corrosion protection is not regarded as a permanent 

upgrade, but is adequate if it continues to meet original lining design 

specifications as determined by periodic inspections. If the lined tank 

does not meet the original design specifications, it no longer meets the 

upgrading requirements and, if it cannot be repaired in accordance with 

industry codes, it is subject to the unprotected tank requirements and 

must be replaced after 1998.

Numerous comments were received suggesting that the use of 

internal tank lining of existing UST systems should be more clearly 

allowed as an upgrade option. Data submitted by the commenters and data 

developed by EPA since proposal indicate that lined tanks rarely cause 

releases to the environment, even in the absence of external corrosion 

protection measures. Tank lining has been reported by lining companies 

as already having been used to repair or prevent releases in over 

300,000 heating oil tanks and over 70,000 motor fuel tanks during the 

last 25 years. Last year, an EPA-sponsored study of UST programs 

outside the U.S. revealed that internal lining of tanks has been in wide 

use in Europe and Canada for the past decade. At least one major 

insurer of USTs in the U.S. requires that unprotected steel tanks over 

15 years of age be lined as a preventive measure for internal corrosion.

Several experienced tank operators commented that if steel 

tanks are properly lined their life can be extended for at least 10 

years with leak-free performance. They noted significant economic and 

operational advantages to lining alone as an upgrade (e.g., it avoids 

the need to reinstall the tank and can be done relatively quickly), and 

they suggested that EPA allow tank lining as an upgrade option. EPA now 
believes that either tank lining alone or tank lining combined with 

external cathodic protection is a reliable upgrade measure. 

Accordingly, the final rule has been revised to more clearly indicate 

that these are acceptable upgrade options under specific guidelines and 

requirements.

EPA also agrees with commenters that internal corrosion is 

a potential problem for tanks in the future but does not believe enough 

evidence is available to suggest that requiring tank lining for all 

steel tanks is warranted at this time. Although commenters submitted 

data that demonstrated the existence of internal corrosion, there were 

conflicting views as to its frequency and causes and the severity of its 

effects. Some commenters stated that all tanks more than 15 years old 

should be lined because of the potential for failures due to internal 

corrosion. Other commenters stated that modern fuels and tank 

management practices have virtually eliminated internal corrosion.

As previously addressed in the discussion of internal 

corrosion under the new tank standards (section IV.B.1.d.), EPA believes 

that most internal corrosion incidents have been due to dip-sticking 

tanks without striker plates. Now that striker plates are standard 

equipment on tanks, the problem of internal corrosion for newer tanks 

has been substantially resolved. In the final rules, tanks over 10 

years of age must be either internally inspected or lined to meet the 

upgrade requirements. If internal corrosion is occurring, the internal 

inspection will detect it. The lining codes require the installation of 

striker plates. Although EPA will continue to study this potential 

problem in the coming years, the final rule does not require internal 

corrosion protection practices beyond what is now contained in industry 

codes.

(2) Cathodic Protection.

A second option for upgrading a tank is cathodic 

protection. Section 280.21(b)(2) describes requirements for upgrading 

an existing UST by cathodic protection. The cathodic protection system 

must meet the requirements for new tank systems, except that the tank 

and piping do not need to have an external dielectric coating. These 

cathodic protection requirements for existing USTs were included in the 

proposal and were supported by the commenters. Several commenters, 

however, expressed concern that not all existing USTs are sound enough 

to be upgraded.

Concern was expressed over allowing cathodic protection 

retrofits on old tanks that could have one of the following: plugged 

corrosion holes (see new causes of release information in section 

II.F.2. of this preamble); severe external pitting corrosion that leaves 

a lower margin of safety in the event that the cathodic protection 

system fails; and internal corrosion. The Agency agrees with these 

commenters that only sound tanks should be upgraded with cathodic 

protection and is including inspection and testing requirements for 

upgraded tanks in the final rule. Review of industry standards for 

internal inspection to assess the need for repair of USTs has convinced 
EPA that tanks can be safely upgraded if these industry standards are 

followed.

There are three ways to ensure that tanks are safely and 

correctly upgraded with cathodic protection. First, tank tightness 

testing may be used to judge the structural integrity of newer tanks 

that are upgraded with cathodic protection, because EPA has concluded 

that newer tanks are much less likely to have corrosion holes than older 

tanks. This option for tank tightness testing may be used only on tanks 

under 10 years of age. EPA concluded in "Causes of Release from UST 

Systems" that corrosion breakthrough is unlikely in unprotected tanks 

under 10 years of age. For example, in one study less than 2 percent of 

tanks tested which were under 11 years of age were found to be leaking. 

Tightness testing will, therefore, adequately identify the few younger 

tanks that may be currently leaking or have corrosion holes. However, 

the younger tanks must be tightness tested twice. The first tightness 

test must be performed before the installation of cathodic protection to 

ensure that the tank is not currently leaking. The second tightness 

test must be performed between 3 and 6 months after the initiation of 

cathodic protection to ensure that the cathodic protection has not 

opened any holes that were previously plugged with corrosion products. 

Information obtained from EPA-sponsored expert panels and public 

comments indicated that corrosion holes often do not leak because the 

corrosion byproducts plug the holes. This information also indicated 

that cathodic protection can cause these "rust plugs" to loosen and 

begin leaking soon after the protection is applied. Although EPA does 

not have data on how often this loosening occurs, this phenomenon 

appears to have occurred in a few cases when cathodic protection was 

applied to gas pipelines. EPA believes that performing a second tank 

tightness test 3 to 6 months after cathodic protection is applied will 

usually detect this type of leak before significant releases occur.

A second way to ensure this type of upgrading is successful 

is to use monthly monitoring. Like the tightness testing option, this 

method may be used only on tanks under 10 years of age. EPA believes 

that very few tanks under 10 years of age will leak after cathodic 

protection has been installed. The Agency believes, however, that some 

method of assessment is needed to protect human health and the 

environment in the unlikely event that an unsound tank is retrofitted 

with cathodic protection. As discussed in section III.D. of this 

preamble, monthly release detection provides highly reliable indications 

of tank integrity.

A third method applies to older tanks. For tanks 10 of age 

and older, these two methods above (either a pair of tank tightness 

tests or monthly release detection monitoring) are inadequate to ensure 

structural soundness before the cathodic protection system is installed. 

These older tanks must instead be internally inspected and assessed. 

As described above, unprotected tanks often corrode through but do not 

leak because the corrosion product, backfill, and interior sludge seal 

the hole. EPA concluded in "Causes of Release from UST Systems" that 

about 50 percent of the corrosion holes in tanks are plugged and do not 

leak. The study also showed that approximately 7 percent of the tanks 

of 12 to 15 years of age leaked. EPA has concluded from these data that 
as many as 7 percent of existing USTs are corroded through, but not 

leaking. Many more existing tanks may be heavily corroded and not 

suitable for cathodic protection alone as an upgrading measure.

EPA understands that several firms that offer cathodic 

protection upgrade services use other methods to ensure that the tank is 

structurally sound before this upgrade option is recommended. These 

procedures appear to vary somewhat from firm to firm. One component of 

the approach commonly involves a statistical analysis of the likelihood 

of the tank having corrosion holes based upon the characteristics of the 

site soils and the age of the tank. The database for this analysis 

varies, but usually contains large numbers of tank failures from Canada 

and the United States.

This approach appears to have merit, but it is not included 

explicitly in the final rule because its effectiveness was not fully 

demonstrated. The Agency was unable to evaluate its effectiveness for 

two reasons. First, EPA does not have long-term performance data for a 

large number of tanks that have been assessed in this way prior to 

upgrading. Second, these practices vary from firm to firm and are not 

established in an industry consensus code. Such options for assessment 

may be used, however, where they have been determined by the 

implementing agency to prevent releases in a manner that is no less 

protective of human health and the environment than internal inspection 

or tightness testing.

EPA proposed that the cathodic protection system for 

upgraded tanks be designed by an independent corrosion expert. 

Commenters opposed to the requirement that the corrosion expert be 

independent were concerned that this was precluding the use of in-house 

personnel. The issue of independence is discussed earlier in this 

preamble in relation to the design of field-installed cathodic 

protection systems for new tank systems (section IV.B.1.). EPA agrees 

with these commenters that companies should be able to use their own 

qualified or trained employees. Accordingly, EPA has dropped the 

requirement that the corrosion expert be "independent."

Commenters also suggested that, because the proposed rule 

required that a corrosion expert design the retrofit cathodic protection 

system, the final rule should not dictate a particular cathodic 

protection system design. EPA agrees with these commenters and has 

decided not to require a specific retrofit cathodic protection method in 

the final rule provided that a corrosion expert determines the 

appropriate method based on the conditions at the site.
(3) Cathodic Protection and Internal Lining.

A third option is to both line and cathodically protect the 

tank. The lining is intended to provide protection from internal 

corrosion; the cathodic protection prevents exterior corrosion. Because 

internal corrosion rarely occurs above the bottom third of the tank, a 

full lining may not be required if an internal inspection shows a sound 

tank exterior. The cathodic protection system must meet the same 

requirements as the new tank cathodic protection system except for 

dielectric coatings. The lining must be installed in accordance with 

the requirements of § 280.33.

c. Upgrading Piping (§ 280.21(c))

Upgrading of an UST system requires upgrading the system's 

piping as well. Metal piping must be upgraded in accordance with the 

requirements for new piping, except that a dielectric coating is not 

required if the existing piping is not upgraded by replacement. Pipe 

lining is a developing technology that may eventually become a viable 

option for upgrading some types of steel pipes; however, the technology 

requires more development and testing to prove its effectiveness for use 

on small-diameter pipes and thus is not an option for upgrading in the 

final rule.

d. Tank Upgrading Methods for Spill and Overfill Control 

(§ 280.21(d))

To prevent spills and overfills associated with product 

transfer to the UST system, all existing UST systems must comply with 

the requirements for new UST system spill and overfill prevention 

equipment, as specified in § 280.20(c). These additional requirements 

are discussed below in section IV.C.1.

4. Notification (§ 280.22)

Section 280.22 of the proposed rule included notification 

requirements for new and existing UST systems. These requirements are 

substantially the same in today's final rule. Sections 280.22(a), (b), 

and (g) have been deleted because their effective dates have passed. 

Section VII of the notification form (certification of compliance) has 

been revised to reflect changed language in the installation, release 

detection, and corrosion protection requirements. The five tank columns 

on this section of the notification form have been deleted to simplify 

the form. EPA believes that the same installation assurance, release 

detection, corrosion protection and financial responsibility measures 

will usually be used at all of the new tank systems at any one location. 

Any sites where different measures are used for each tank can be 

certified with copies of this form.
C. General Operating Requirements

1. Spill and Overfill Prevention and Control (§§ 280.20 and 280.30)

a. Introduction

The surface spills and overfills that occur at UST systems 

are usually the result of human error, not equipment failure. There are 

two major types of surface releases: (1) spilling, which results from 

improper dispensing practices such as disconnecting the delivery hose 

from the tank's fill pipe before the hose has drained completely, and 

(2) overfilling, which occurs when the tank liquid level exceeds tank 

capacity and product escapes through tank bung holes, vent lines, or 

fill ports. Spills and overfills occur on a relatively frequent basis; 

however, they are usually not reported because they are typically small 

in volume--less than 25 gallons--and can be easily contained and cleaned 

up.

Basically, the proposal required owners and operators to 

follow procedures and provide equipment to prevent these releases or to 

immediately contain and clean them up. In the proposed rule, proper 

transfer procedures had to be followed during all deliveries. For new 

UST systems, the Agency proposed the installation of alarms in 

conjunction with liquid level sensors, automatic shutoff devices that 

halt further delivery of product into the UST at a predetermined level, 

or the installation of catchment basins to contain overfills or spills 

(e.g., product left in delivery hoses at the time of disconnect). EPA 

also proposed requiring the immediate installation of spill and overfill 

equipment on any UST system that used external leak detection devices. 

Existing UST systems not using external leak detection devices were 

allowed up to 10 years to come into compliance with the proposed 

requirements for spill and overfill equipment.

In the Agency's study of the causes of releases from UST 

systems completed since proposal, many people contacted and interviewed 

in the field ranked spills and overfills as the most frequent cause of 

release rather than the distant third identified in the preamble to the 

proposal (52 FR 12667). For example, spills and overfills are reported 

in Dade County, Florida, to be the leading cause of release from UST 

systems. Experienced installation contractors reported that they 

repeatedly and frequently observe various indicators of spill and 

overfill problems, such as discolored soil above and around the tank and 

the dissolving of the tank's bituminous coating below the drop tube 

connection to the tank fill opening. Field observations also implicated 

nonoperational components such as bung hole plugs and vent lines as a 

frequent cause of release in overfills. In addition, most experienced 

hands in the field felt that spills and overfills were two separate 

problems that must be addressed separately.

Based upon public comments and new findings on causes of 

product release, the Agency has made several changes in today's final 

rule for spills and overfills: the rule has been reorganized to address 
apparent confusion voiced by commenters concerning the presentation of 

requirements for new and existing USTs; an exemption from equipment 

requirements is provided for UST systems filled with small volume 

delivery of no more than 25 gallons; and the physical presence of an 

attendant is not required during the filling of the UST system as long 

as the transfer operation is otherwise monitored by mechanical or 

electronic means. Although EPA recognizes that the owner and operator 

may, through private agreement, ensure that ultimate responsibility for 

the exercise of proper delivery techniques is borne by the transport 

carrier, the final rule still holds the owner and operator responsible 

for preventing damages to human health and the environment due to spills 

because the Agency does not have jurisdiction over transport carriers.

The specific spill and overfill equipment requirements of 

the final rule are discussed below. These requirements apply to all new 

UST systems as of the effective date of this rulemaking, and existing 

UST systems must meet the requirements within 10 years of that effective 

date (see section IV.C.1.e. below). In addition, general operating 

procedures for spill and overfill control are applicable to both new and 

existing UST systems as of the effective date of the rule (see section 

IV.C.1.f. below). 

b. Spill Prevention (§ 280.20(c)(1)(i))

The Agency has concluded that repeated spills can 

frequently cause significant environmental damage. Although most 

surface spills are small in volume, because they are often repeated they 

can eventually contaminate soil and ground water. Thus, the final rule 

requires use of spill prevention equipment (such as a small catchment 

basin around the fill port) at all new and existing UST systems. 

Catchment basins are the most prevalent form of spill prevention used 

today.

The proposed rule specified that when catchment basins were 

used they would be large enough to contain the volume of the hose. In 

response, several commenters objected to EPA relying on this larger 

sized catchment basin technology because of concerns about the potential 

fire or explosion hazard resulting from the buildup of petroleum fumes 

in the catchment basin area, the cracking of catchment basins due to 

freezing of accumulated water, or the potential that these containment 

devices would provide the deliverer with a false sense of security that 

would prompt carelessness during delivery. However, no commenters 

provided any data to EPA that indicated the occurrence of any fires or 

explosions due to vaporization of product in a basin, regardless of its 

size. In any event, EPA believes that compliance with the proper 

transfer procedures required in § 280.30(a) will prevent fuel from 

frequently collecting in the basins, and normal maintenance suggested by 

the equipment manufacturer will prevent water from accumulating and 

freezing. Several commenters said that small spill catchment basins are 

preferred in many circumstances. They also said that if overfill 

prevention equipment is also used, the problem of emptying a full 

transfer hose should rarely be encountered. Overfill prevention devices 

currently available in the United States either allow the transfer hose 
to drain at a very slow rate into the tank or can be manually overridden 

to empty the hose contents into the tank. As a consequence, today's 

final rule deletes the proposed size specification for spill catchment 

basins, thus leaving the determination of the appropriate volume to the 

discretion of the owner and operator. The design or size of the 

catchment basin (combined with the type of overfill prevention equipment 

also being required today) should be of sufficient size to contain 

spills and prevent releases to the environment. For example, if the 

catchment basin has a means for releasing its contents into the tank or 

another containment structure in order to provide more room in the 

catchment basin, a smaller volume catchment basin (e.g., the standard 5-

gallon size) should be adequate equipment for preventing spills. 

Catchment basins without any means for drainage and requiring manual 

unloading may need to be of larger volume.

For those concerned that the use of catchment basins of any 

size or type may present a safety hazard, EPA allows use of alternative 

devices to prevent spills if they are approved by the implementing 

agency as preventing spills in a manner that is no less stringent in 

protecting human health and the environment. For example, a device that 

would prevent release from the transfer hose when detached from the fill 

pipe, such as a dry disconnect coupling, could satisfy this requirement. 

This provision is intended to provide flexibility in a rapidly 

developing technological area that will allow continued development of 

new and improved spill prevention equipment.

c. Overfill Prevention (§ 280.20(c)(l)(ii))

Agency data show that overfill prevention is also very 

important, not just for the prevention of large overfills released from 

the top of vent or fill lines, but also overfills that slowly leak out 

from the fittings at the top of the overfilled tank, such as the bung 

connections. In today's final rule, therefore, all new UST systems are 

also required to use overfill prevention equipment.

All new UST systems must be equipped with overfill 

protection by installing one or more of the following:

oA device that will alert the transfer operator when the 

tank is no more than 90 percent full by restricting the 

flow into the tank or triggering a high-level alarm;

oA device that will automatically shut off flow into the 

tank when the tank is no more than 95 percent full; or

o An equivalent device approved by the implementing 

agency.

These alternatives are essentially the same as those 

presented in the proposed rule except for the clarification that flow 

restrictors (i.e., ball float valves) are also allowed. Although not 

specifically mentioned in the proposed rule, several commenters felt 

that flow restrictors were adequate for spill and overfill prevention 

and are the most widely used method at present. Flow restrictors do not 
shut off inflow completely but instead significantly reduce the rate at 

which product enters the tank. The transporter can tell when the flow 

is reduced and stop delivery. Some commenters emphasized that many USTs 

are already using flow restrictors successfully. Upon review of these 

devices, the Agency has concluded that the flow restrictors are 

protective of human health and the environment, particularly if they are 

coupled with the requirement of § 280.30 that all transfers be closely 

monitored. The final rule allows the use of flow restrictors for 

overfill prevention.

EPA is concerned, however, that this type of overfill 

prevention may jeopardize the integrity of the tank if a pressurized 

product delivery system is used. Pressurized transfer of up to 30 psi 

is sometimes used with heavier fuels. Most tanks can safely withstand 

pressures of only 5 psi, and flow restrictors may allow a much higher 

pressure to develop during pressurized delivery, causing tanks to 

rupture. The Agency has no information to indicate that such failures 

are common. Almost all of the UST systems addressed in today's rule are 

not filled by pressurized delivery. The delivery hose connection for 

this type of delivery usually includes a back-pressure sensor that 

automatically disconnects the hose if pressure develops in the tank.

EPA has decided that if an owner and operator uses either a 

high-level alarm or a flow restrictor, the devices must be activated at 

90 percent of tank capacity. In the proposal, the high-level alarms 

were required to be activated at 95 percent of tank capacity. EPA has 

decided on the stricter standard for both of these devices because 

neither device is a total shutoff device. Also, both devices are 

subject to the operator's response to terminate the transfer.

Automatic shutoff devices do not require operator action to 

prevent overfills. Automatic shutoff devices prevent overfilling by 

automatically shutting off flow at the fill pipe before the tank fills 

up to the top. Already in widespread use in Europe, this approach is 

designed to completely eliminate overfills due to human error. The 

Agency believes this is the simplest type of overfill device for new and 

existing UST systems installing overfill prevention equipment. 

Inexpensive shutoff devices that are easy to install have recently 

become available to the U.S. market, with the potential for additional 

innovative technology to enter the market soon. Those who wish to use 

an overfill prevention device other than those mentioned in the rule may 

satisfy the overfill prevention requirement with use of alternative 

devices approved by the implementing agency as being no less stringent 

in protecting human health and the environment.
d. Exemptions (§ 280.20(c)(2))

Several commenters pointed out that infrequently filled UST 

systems pose less risk of releases from spilling and overfilling than 

systems filled on a more regular basis and, therefore, should be exempt 

from spill and overfill prevention equipment requirements. Other 

commenters suggested that UST systems filled manually in small 

increments, such as most used oil tanks, pose significantly less risk 

than those receiving large-volume deliveries.

The Agency is continuing to require spill and overfill 

prevention equipment on infrequently filled tanks in the final rule. 

Though a tank may be filled only occasionally, it is the potential size 

of overfills that concerns EPA. Although infrequent filling reduces the 

likelihood of a spill or an overfill release somewhat, it does not 

guarantee that a spill or an overfill that does occur would be of small 

quantity. In addition, EPA feels that in the future, as today's 

requirements are implemented, carriers of product may become accustomed 

to (and dependent on) devices such as high-level alarms or shutoff 

devices and would, therefore, be less attentive during product delivery 

due to reliance on prevention equipment to indicate completion of the 

delivery. Finally, the implementing agency would often be unable to 

determine the actual filling frequency for purposes of determining 

whether a particular UST system should be exempt from spill and overfill 

requirements, creating compliance monitoring difficulties. 

Consequently, the Agency has retained the required use of spill and 

overfill prevention equipment for infrequently filled tanks.

The final rule does not, however, require new UST systems 

filled through transfers of no more than 25 gallons to use spill or 

overfill prevention equipment (§ 280.20). The 25-gallon limit was 

selected because the Agency understands it is a common industry practice 

at automotive service centers to use containers up to this volume for 

handling used oil prior to putting it into the UST. EPA has concluded 

that the likelihood of overfilling the tank is small because the volume 

of the transfer is much smaller than the volume of the tank. In 

addition, the maximum size of the spill or overfill that could occur 

from a 25 gallon transfer is 25 gallons. This quantity is easier to 

contain and clean up than the maximum size spill or overfill that could 

occur from a transfer of several thousand gallons. EPA has concluded 

that proper operating practices and procedures (required under 

§ 280.30), such as checking the available tank volume before each 

transfer, will adequately protect human health and the environment.

e.Compliance Schedule for Initial Spill and Overfill Equipment (§§ 

280.20 and 280.21)

In the proposal, the schedule for compliance required use 

of spill and overfill prevention equipment at the time of installation 

of all new UST systems. All existing UST systems must be upgraded 

within 10 years of the effective date of the final regulations. EPA has 

retained this 10-year requirement as an adequate period of time to 

retrofit existing UST systems.
EPA has deleted the proposed requirement to partially phase 

in the use of spill and overfill equipment whenever any external method 

of detection is installed at an existing tank. Some commenters 

expressed confusion about when such equipment would have to be 

retrofitted to tanks that already have installed external monitoring 

methods. EPA agrees that mandating this phase-in approach does present 

such implementation problems and unnecessarily hinders owner and 

operator flexibility in selecting their own schedule for compliance 

within the 10-year deadline. This proposed approach could unduly 

discourage the use of external methods of detection. Furthermore, 

research completed by EPA after proposal (and made available for public 

comment on March 31, 1988) has convinced the Agency that spills and 

overfills do not pose insurmountable problems to the use of external 

methods of detection that require the immediate retrofit of spill and 

overfill equipment.

As suggested by commenters, EPA considered requiring 

retrofitting spill and overfill prevention devices earlier, for example, 

at the time of installation of all release detection equipment or during 

a scheduled general system upgrade. The Agency decided against such 

earlier deadlines primarily due to the implementation difficulties this 

would pose. EPA believes that the limited population of installers 

precludes the rapid installation of spill and overfill controls at all 

of the UST sites nationwide. Although EPA has decided to retain the 10-

year time period, the Agency expects that many tank owners and operators 

will retrofit these devices in less than 10 years even though it is not 

mandatory to do so. In many cases, retrofit of spill and overfill 

equipment at the time of release detection retrofit or of corrosion 

protection upgrading will be more cost effective. Finally, the less 

stringent release detection requirements that are allowed in today's 

final rules for fully upgraded tanks will actually provide an incentive 

to initiate earlier retrofitting to meet spill and overfill prevention 

requirements. The discussion of release detection requirements for 

upgraded tanks is provided in section V.D. of today's preamble.
f. General Operating Procedures for Spill and Overfill Control 

(§ 280.30)

In addition to installation of release prevention 

equipment, the Agency has retained in the final rule the general 

operating procedures for both new and existing UST systems that were 

proposed to prevent spills and overfills.

Proposed § 280.30(a) stated that the owner and operator 

must ensure that releases do not occur and must be physically present to 

observe the transfer of product. Many commenters suggested that the 

driver of the delivery vehicle should be held responsible for any 

releases during delivery, and that having someone physically present who 

represents the owner and operator during all deliveries is impractical 

and costly. Although EPA agrees that responsible carriers are the 

primary agents in the field to prevent spills and overfills, for the 

purpose of complying with today's requirements, the UST system owner and 

operator is responsible for preventing spills and overfills. The Agency 

must take this approach because it has no legal authority to regulate 

transporters under Subtitle I. Thus, regardless of whether the owner 

and operator decides to share (by contract) responsibility for the 

monitoring of the transfer with the carrier, under today's final 

regulations the owner and operator will continue to be responsible in 

the event that there is a release during delivery. See section 

IV.E.2.d. of the preamble and § 280.53 of the final rule for the 

requirements of owners and operators in the event of a spill or 

overfill.

The proposed rule required that a person be physically 

present at all times during the transfer of product to be able to 

respond quickly to a spill or overfill (proposed § 280.30). Some 

commenters suggested, however, that many UST systems are in large tank 

farms where it would not be feasible or economical (especially during 

multiple filling operations) to have someone present at each tank during 

the time it was being filled. In response to these suggestions, EPA is 

changing this requirement in the final rule to simply require that all 

deliveries be monitored constantly. This change allows for a person at 

the site (but not necessarily at the transfer point) to monitor a 

transfer using remote sensing equipment that can prevent a spill or an 

overfill from occurring. This change will continue to meet the intent 

of the proposed requirement, that delivery be monitored, and will also 

accommodate operations encountered at large tank farms where it is 

difficult for a person to be at every tank. Many of these installations 

have central monitoring stations where all the tanks can be supervised 

through remote control monitoring and shutoff equipment.
2. Operation and Maintenance of Corrosion Protection (§ 280.31)

As discussed in the preamble to the April 17 proposal (52 

FR 12666-12667), corrosion was found to be one of the common causes of 

release in existing underground tank and piping systems that are 

unprotected from corrosion. The consensus of experts in the field 

contacted by EPA indicates that the installation and proper operation 

and maintenance of corrosion protection systems can significantly reduce 

the incidence or volume of release due to corrosion. Officials in 

Ontario, Canada, Denmark, and Sweden have cited the success of such 

corrosion protection programs initiated in their respective countries 

during the early to mid-1970s. The proposed rule addressed operation 

and maintenance of corrosion protection systems in § 280.31 (see 

preamble discussion in 52 FR 12707).

a. Extent of Corrosion Protection (§ 280.31(a))

EPA proposed in § 280.31(a) that all corrosion protection 

systems must be operated and maintained to continuously provide 

corrosion protection to buried metal components of the UST system. 

Public comments on proposed § 280.31 supported the necessity of routine 

maintenance of the corrosion protection systems by qualified field 

personnel.

The Agency also invited comments on which components, if 

any, should be cathodically protected; whether there are noncorrodible 

metal alternatives for that component; and what form of corrosion 

protection is appropriate if cathodic protection is not required (52 FR 

12707). Many comments were received in this area. In summary, some 

commenters suggested that all corrosion-protected metal components of 

UST systems, including swing joints, flexible connectors, and riser 

connections, should be monitored regularly. Other commenters suggested 

that some components, such as bung plugs and the pump housing, do not 

need cathodic protection and maintenance. (As discussed in more detail 

earlier in this preamble in the section on new piping design and 

construction requirements (section IV.B.1.b.(2).) In the final rule, 

EPA requires protection of delivery piping and that portion of the tank 

routinely storing regulated substances. Requirements for spill and 

overfill equipment and practices will prevent releases from the top of 

the tank and vent piping.

EPA agrees with commenters who found it unnecessary to 

require protection for portions of the system that would not regularly 

contain product or are not in contact with the soil, even if situated 

underground. Bung plugs are inserted into unused openings at the top of 

a tank and are not subject to releases except in the event of overfills. 

Delivery piping is defined as that portion of the UST system piping 

through which product is introduced into the tank or delivered from the 

tank. Cathodic protection is not required for the fill pipes of tanks 

that have a drop tube because the drop tube is the part of the tank that 

routinely contains product. The drop tube is not in contact with the 

soil and thus does not require cathodic protection. Vent piping is not 

used for delivery of product and presents a minimum risk for release to 
the environment. In fact, vent piping would be a potential release 

source only in the event of overfill conditions. The release potential 

from bung plugs and vent piping will be eliminated or substantially 

reduced by the requirements for overfill prevention equipment required 

in § 280.30 of today's rule and, therefore, the Agency has not required 

their cathodic protection in today's rule.

Pump housings, when contained in the equipment manway at 

the top of a tank, do not come in contact with the soil and thus do not 

require cathodic protection. Other pump housings are often isolated 

from the soil by being submersed in the product in the tank or situated 

in the dispenser housing above grade and, therefore, do not require 

cathodic protection. Only those pump housings that are in contact with 

the ground and potentially contain product require cathodic protection.

b. Qualifications for Corrosion Personnel (§ 280.31(b))

EPA proposed in § 280.31(b) that all cathodic protection 

systems be inspected and designed by an "independent" corrosion expert. 

Most of the comments received by EPA in this area strongly opposed the

requirement of an "independent" corrosion expert. EPA agrees that the 

proposed requirement for the independence of the expert is not needed 

and has deleted this term from the final rule. (See section 

IV.B.1.a.(2) above for a discussion of this issue.)

Other commenters pointed out that the maintenance, 

operation, and inspection of an installed cathodic protection system 

could be performed by people who have much less training than a 

corrosion expert. EPA agrees with these comments, recognizing that most 

of these inspections are now being conducted by trained specialists. 

Thus, EPA has replaced the term "independent corrosion expert" with 

"qualified cathodic protection tester" in the final rule. Cathodic 

protection testers must be able to demonstrate education and experience 

in the measurement of cathodic protection of buried or submerged metal 

piping systems and metal tanks. A definition to this effect has been 

added to the final rule. The National Association of Corrosion 

Engineers (NACE) has developed an examination that can be used to ensure 

that cathodic protection testers are qualified.
c. Inspection Schedule (§§ 280.31(b) and (c))

EPA proposed a minimum inspection schedule for cathodic 

protection systems in § 280.31(b). For field-installed cathodic 

protection systems, the proposal required that the system be tested 

within 6 months of installation and at least annually thereafter. For 

factory-installed cathodic protection systems, it was proposed that each 

system should be tested within 6 months of installation and at least 

every 5 years thereafter. For all impressed current systems, the 

proposed requirement was inspection and/or testing as appropriate, and 

at least annually. The Agency invited comments on the advantages and 

disadvantages of allowing less frequent inspections/testings for those 

tanks that are equipped with premanufactured corrosion protection (52 FR 

12707).

Several comments were received in these areas. Some 

commenters felt that the proposed testing requirements for field 

installation were excessive and that there is no technical reason to 

differentiate between field- and factory-installed systems. After 

consultation with groups of industry experts during the public comment 

period, EPA now agrees with the commenters who recommended that all 

cathodic protection systems should be tested at the same frequency and 

the Agency is now requiring in the final rule that all cathodic 

protection systems be tested within 6 months of installation and at

least every 3 years thereafter. These intervals are sufficient to 

detect any damage or failure of the system and to take remedial action 

in time to prevent structural failures due to corrosion. EPA 

understands that this time interval is consistent with sound practice as 

is now recommended in the recently revised NACE code and by major tank 

manufacturers.

EPA proposed in § 280.31(c) that all UST systems with 

impressed current cathodic protection systems must be inspected every 60 

days to ensure that the equipment is running properly. This equipment 

inspection is required in addition to the testing of the cathodic 

protection. EPA has received many comments on this section. Several 

commenters supported the proposed approach, with some further suggesting

that impressed current systems must be inspected six times a year with 

intervals not exceeding 75 days. Some commenters suggested monthly 

inspection of all systems while others suggested immediate testing after 

installation for all impressed current systems and annually thereafter. 

No commenters stated that periodic testing of an impressed current 

system should not be required.

EPA agrees with the commenters who said that inspection at 

60-day intervals is protective of human health and the environment 

because loss of power to the anodes for 60 days is very unlikely to 

result in corrosion failure. Thus, the proposed inspection approach has 

been retained in the final rule. This inspection is conducted to simply 

ensure that the equipment is running properly and is relatively 

straightforward for most impressed current systems. Most of these 

systems include a light on the control panel that indicates proper 

operation. No special training is required to perform this inspection.
d. Recordkeeping (§ 280.31(d))

EPA proposed in § 280.31(d) that records documenting the 

proper operation of corrosion protection systems must be maintained. 

EPA requested comments on this proposed requirement, and none were 

received. The Agency has made slight changes in the wording of this 

requirement to make the intent of the final requirement clear. This 

minor change does not change the substance of the proposed requirement. 

The records that are maintained must provide the results of testing 

from the last two service checks required in § 280.31(b) (which must be 

performed by a corrosion protection tester) and the last three 

inspections required under § 280.31(c) (which can be performed by the 

owner and operator). EPA believes that this record will provide 

sufficient information to demonstrate that the proper operation and 

maintenance of the cathodic protection system is being carried out.

e. General Performance Standards for Testing

Section 280.31(e) also proposed three criteria to be used 

while testing cathodic protection systems. EPA received several 

comments regarding this approach, with most of them suggesting that EPA 

should include all of the five criteria as defined in NACE RP-02-85. 

Based on the suggestions of these commenters, EPA now believes that 

industry codes, such as NACE RP-02-85 and API's "Guide for Inspection of 

Refinery Equipment," developed by nationally recognized associations 

provide clearer and more complete guidance about the use of these 

criteria to determine the adequacy of cathodic protection. These 

criteria are also better explained in technical documents such as these 

industry codes. In addition, these criteria are subject to continued 

review and can be revised to reflect new measurement techniques that 

result from increased understanding of corrosion phenomena.

Accordingly, § 280.31(e) has been deleted, and there is no 

explicit listing of the three criteria from the proposed rule. The 

proposed criteria have been replaced with a more general performance 

standard (in § 280.31(b)) that requires the service checks be performed 

in accordance with a nationally accepted code of practice. This 

approach accommodates the concerns of the commenters who recommended 

that all five of the NACE criteria should be allowed to be considered. 

At the same time, this approach encourages the application of the proper 

standard because these national codes are presented within the context 

of significant technical guidance as to the proper use of each criteria. 

Thus, in the final rule, owners and operators are being held to the use 

of at least these criteria as recommended in these national codes.
f. Notification Requirement

EPA proposed in § 280.31(f) that owners and operators of 

new UST systems must certify compliance with the corrosion protection 

requirements on the notification form submitted pursuant to § 280.22. 

No comments were received by EPA on this requirement. In the final 

rule, this section has been moved for clarity to § 280.22(e), which 

identifies notification requirements.

3. Inspection and Maintenance of the Tank System

In the preamble to the proposed regulation, the Agency 

discussed three alternatives for the required maintenance and inspection

of the tank system (52 FR 12707). EPA proposed requirements for the 

maintenance and inspection of corrosion protection systems and requested 

comments and information on the need for broader requirements. Two 

alternatives were described that addressed the maintenance and 

inspection of the entire site or other tank system equipment in addition 

to the corrosion protection system.

a. Site or System Inspections

Many comments were received by EPA on these alternative 

inspection requirements. Some commenters felt that inspection of the 

entire site or of the tank system is of little practical benefit and 

unnecessary because such an inspection alternative would be duplicative 

of the leak detection requirements. One commenter suggested conducting 

inspections of the entire UST site.

EPA agrees with commenters who stated that site inspection 

is duplicative of leak detection. Institution of release detection 

systems should provide effective warning of releases from most of the 

components of the tank system, thereby eliminating the need to require 

the general inspections. Also, the majority of USTs are completely 

underground and inaccessible to inspection, rendering total system 

inspection impractical. 
b. Inspections for Tank Deflection

Small distortions of the tank diameter are expected at the 

installation of USTs, and the tanks are designed with an allowance to 

withstand them. Improper backfill or failure to install foundation 

anchors (or failure of the anchoring system) can lead, however, to 

excessive distortion resulting in rupture of the tank. One way to 

verify this distortion is by measuring tank deflection (variation from 

true diameter). EPA had requested comments on periodic tank deflection 

measurements for steel or FRP tanks as a means of preventing tank 

failures. Many comments were received by EPA on this inspection method. 

Some requested EPA to mandate periodic deflection monitoring for FRP 

tanks in the final rule. Others stated the view that FRP tanks do not 

require periodic deflection monitoring because virtually all deflection 

ceases after the first year. Some also recommended vertical diameter 

measurements for all new tanks to verify initial installation results.

The Agency disagrees with commenters who suggested periodic 

tank deflection monitoring for FRP tanks. The low incidence of failure 

in FRP tanks (less than 0.5 percent), which has been declining 

substantially over the last 10 years, argues against the need for 

periodic deflection measurements. The Agency has, therefore, chosen not 

to mandate periodic deflection measurement in the final rule. The 

Agency believes that excessive deflection in FRP tanks is usually due to 

improper installation and occurs soon after the installation is 

complete. Deflection measurements during and immediately following 

installation are required by the tank manufacturers for purposes of 

warranty validation. EPA believes that these are sufficient for the 

protection of human health and the environment.

In addition, investigators conducting a study of deflection 

monitoring of FRP tanks in Suffolk County (New York) have reported to 

EPA that the deflection measurement is often difficult to obtain unless 

special provisions are made for taking this measurement when the tank is 

installed. Special tools and training are required to prevent damage to 

the fill pipe tank seal (53 FR 10403) when obtaining access to the tank 

for conducting the test.
c. Monitoring Corrosion Protection at Composite Tanks

The Agency had also requested comments on requiring 

corrosion protection inspections for composite tanks. Some commenters 

stated that composite tanks should be monitored to ensure the integrity 

of the FRP coating, using the same criteria used for the cathodic 

protection inspections. Others felt that inspections of composite tanks 

are unnecessary after installation. The Agency disagrees with the 

commenters who recommended that composite tanks be periodically 

monitored to ensure the integrity of the FRP coating. It has been 

reported to EPA that most composite tanks pass when tested through the 

measurement of electrical continuity between some structure of the tank 

and the soil; however, the tanks that have "failed" this test showed no 

evidence of external corrosion once they were excavated and inspected. 

This is a point of continuing controversy within the National 

Association of Corrosion Engineers. Based on the superior performance 

of composite tanks to date (no documented failures due to external 

corrosion), EPA has decided not to mandate the corrosion protection 

monitoring of composite tanks in the final rule.

4. Compatibility (§ 280.32)

In the proposed rule, EPA set forth a general performance 

standard requiring owners and operators to use an UST system made of or 

lined with materials compatible with its stored substances. 

Incompatibility could result in the structural deterioration of the 

containment vessel or piping and cause releases into the environment 

(see 52 FR 12708-12710). Because EPA has found no significant evidence 

that incompatibility is a cause of release from USTs, the final rule 

contains no additional requirements and thus remains the same as 

proposed.

a. Compatibility of FRP Tanks with Alcohol-Blended Fuels

Since the proposal appeared, EPA sought additional 

information on problems reportedly caused by incompatibility of FRP 

tanks and alcohol-blended fuels. This search included conversations 

with several groups very familiar with these fuels and the FRP tank 

industry. In all of the information reviewed, only one release case was 

suspected to be caused by incompatibility problems. In addition, EPA 

has been unable to find any demonstrated incompatibility problem with 

10-percent alcohol-blended fuels and FRP tank systems.

There are two types of FRP tanks. The standard FRP tank is 

compatible with up to 10-percent alcohol-blended fuels. The second type 

of FRP tank is manufactured with a special resin that ensures 

compatibility with blended fuels containing greater than 10-percent 

alcohol. Although the higher percentage alcohol-blended fuels (11 to 

100 percent) might, over long periods of time, (at least theoretically) 

pose compatibility problems in standard FRP tanks, the actual threat 

posed is believed to be very small for two reasons. First, the current 

and projected use of oxygenated fuels shows a trend that will increase 
the use of 10-percent alcohol-blended fuels but that will not increase 

the percentage of alcohol in the fuels. Second, information provided to 

the Agency indicates that numerous facets of industry (tank 

manufacturers, tank owners, and distributors) are very aware of and 

concerned with alcohol-blended fuels and FRP tank and piping 

compatibility problems. Industry practice is for the tank owner or 

operator to contact the manufacturer when a different product is to be 

stored, thus allowing the manufacturer to check its records concerning 

the compatibility of the stored substance and existing tank system. 

Numerous tanks have been relined with different resins that are 

compatible with the new fuels. EPA has added a note to the performance 

standard which refers to industry codes that can be used as guidance to 

help owners and operators with alcohol-blended fuels satisfy the 

compatibility requirement.

5. Repairs (§ 280.33)

In § 280.33 of the proposed rule, EPA proposed conditions 

under which repairs to an UST would be allowed. As discussed in the 

preamble to the proposal (52 FR 12710-12711), numerous state UST 

programs already address this topic in their regulations. Eight state 

programs refer to industry guidelines that should be followed in making 

repairs. Since proposal, EPA has continued to investigate the subject 

of UST system repairs. Numerous commenters on the proposal addressed 

this subject. It is obvious from the response received and other work 

undertaken by the Agency that there is a great deal of interest and 

ongoing activity in the field of UST management concerned with UST 

system repairs (including the development of new codes and practices). 

As discussed below, today's final rule incorporates several changes to 

the proposed requirements concerning UST repairs, including the deletion 

of, revision of, and addition to several of the conditions in the 

proposal.

a. Repair and Lining (§ 280.33(a))

Under § 280.33(a), EPA proposed to allow the repair and 

lining of a tank if four requirements were met: (1) a vacuum test was 

conducted, (2) the lining material was compatible with the regulated 

substance stored, (3) the tank was inspected internally and 

ultrasonically tested, and (4) the tank had not been repaired or relined 

previously. Today's final rule revises some of these proposed 

requirements as discussed below.

In § 280.33(a)(1), EPA proposed requiring that a vacuum 

test be conducted on repaired tanks. This requirement was intended to 

ensure sound repairs (52 FR 12711). The vacuum test is no longer 

required for reasons that are discussed in more detail in subsection d. 

below.

In § 280.33(a)(2), EPA proposed requiring that the lining 

material applied to the interior of the tank be compatible with the 

regulated substance stored. All commenters that agreed this provision 
was necessary and pointed out that it is one that is already being 

followed in current industry practice. The specific requirement has, 

therefore, been deleted but the lining material is still required in the 

final rule to be compatible with the regulated substance stored in the 

tank because this concern is incorporated into all current codes and 

practices and one of these must be followed under the final rule.

In § 280.33(a)(3), EPA proposed internal inspection and 

ultrasonic testing of a tank to determine that it was structurally 

sound. Under today's final rule, the tank must still be internally 

inspected and determined to be structurally sound, but the ultrasonic 

test is no longer required. EPA received comments concerning the 

methods to test a tank to ensure that it is still structurally sound. 

These comments indicated that alternative tests were available to 

determine the structural integrity of the tank. National codes, 

including API 1631 and NLPA 631, provide alternative methods. Currently 

available data submitted and developed independently by EPA concerning 

field performance of tank lining indicate that if these codes are 

followed, the lined tanks will perform very well (see the discussion of 

interior lining under the upgrading section presented earlier in this 

preamble). EPA has learned that Underwriters Laboratories is currently 

developing a performance test (Subject 1856); however, it is still in 

the draft stage at this time. Consequently, today's final rule reflects 

the conclusion that it is not necessary to require a specific test to 

ensure structural soundness. Thus, EPA has substituted a performance 

requirement in § 280.33(d)(1) of the final rule that the internal 

inspection be conducted in accordance with codes of practice developed 

by a nationally recognized association or independent testing 

laboratory.

For purposes of assisting implementation of this general 

requirement, the final rule includes the note that the lining and repair 

procedures described in API 1631 and NLPA 631 may be used to comply with 

§ 280.33(a). These codes describe test protocols for inspecting tanks 

to determine the structural soundness. The use of the ball peen hammer 

test is described, as well as the use of ultrasound. The codes include 

criteria for minimum allowable remaining thickness and maximum number of 

perforations per unit area in determining the condition of the tank. 

The codes also specify tests to ensure that the repair or lining has 

been performed correctly. EPA intends by this approach to allow other 

applicable national codes (such as UL 1856) developed in the future to 

be used in meeting this requirement.

In § 280.33(a)(4), EPA proposed limiting UST repair to only 

tanks that had not been previously repaired. In other words, a tank 

could be repaired only once so as to avoid continued repair of an UST 

that was fundamentally unsound (52 FR 12711). Some of the commenters 

suggested that, under this approach, EPA needed to resolve definitional 

questions concerning what constitutes a repair versus simple preventive 

maintenance. They expressed concern that the proposed one-time repair 

provision might preclude the use of preventive maintenance that would 

otherwise prevent leaks. Other commenters opposed this requirement, 

stating that structurally sound tanks could be repaired repeatedly; they 

also provided extensive data showing that repaired tanks had an 
excellent performance record. Other commenters opposed allowing any 

repairs to tanks that had leaked.

After study of the comments, review of the submitted 

performance data on repaired tanks, and further study of the codes, EPA 

agrees that restricting repair to a single time is unnecessary. The 

submitted record of repaired tanks was found to be very good and 

numerous EPA contacts with tank lining users and regulators have 

generally confirmed the accuracy of this performance record. Therefore, 

EPA has concluded that the tank repair codes already in existence (and 

in use for years) provide adequate standards and guidelines for 

determining if a particular tank qualifies for repair. Consequently, 

EPA has not included the one-time only repair requirement in the final 

rule and will allow tanks to be repaired more than once provided that 

they meet the standards for repairability in the applicable codes and 

that the repair is completed in compliance with these standards. If a 

tank has leaked product, however, the requirements for corrective action 

must be met and will sometimes require removal of the tank in order to 

complete the appropriate cleanup measures even if it is determined to be 

structurally sound and repairable.

b. Cathodic Protection (§ 280.33(e))

In § 280.33(b), EPA proposed that all steel tanks with 

corrosion holes that are subsequently repaired be retrofitted with a 

cathodic protection system that is designed by an independent corrosion 

expert and operated and maintained in accordance with § 280.31. Again, 

comments were received objecting to the requirement of the use of an 

"independent" corrosion expert on the grounds that many companies employ 

corrosion experts and that requiring an independent expert would be 

unnecessary and burdensome. As discussed earlier in this preamble in 

section IV.B.1.a., EPA is dropping the requirement for an "independent" 

corrosion expert in the final rule.

Comments were also received indicating that the addition of 

a cathodic protection system to a tank that was repaired by lining was 

not necessary and represented a significant additional expense. In view 

of the excellent performance record to date with relined tanks, EPA 

agrees with this point to some extent. Accordingly, in the final rule, 

EPA will allow lining alone as an upgrade alternative for corrosion 

protection provided that it is done within the confines of one of the 

national codes. In other words, a tank that is determined to be 

structurally sound under the criteria in the codes may be upgraded by 

lining alone for a 10-year period. The interior of the tank must be 

reinspected at the end of the 10-year period following the lining. If 

this inspection shows the tank is still sound, again in conformance with 

the existing codes, the upgrade can be extended for use for another 5 

years. Thus, in the final rule, lining alone (without cathodic 

protection) provides an allowable upgrade for corrosion protection for a 

10-year period. This period may be extended in 5-year increments by 

inspecting the tank according to the codes and demonstrating that the 

tank is still sound and that the lining can prevent releases for another 

5 years.
c. Authorized Repair for FRP Tanks (§ 280.33(b))

In § 280.33(c), EPA proposed that repairs to FRP tanks be 

made only by the manufacturer's authorized representatives. Many 

comments were received opposing this proposed requirement. 

Commenters argued that qualified in-house personnel should 

be allowed to perform repairs and that such a restriction would limit 

the opportunity for private enterprise and small businesses to enter 

into the FRP repair industry. They also expressed concerns that 

restricting repairs to the manufacturer's authorized representatives 

would increase the cost to the owners and operators. Finally, they 

believed that such a restriction could result in insufficient repair 

capability and cause delays in repair, particularly in less populated 

and more remote regions.

Several comments were also received that supported the 

proposed requirements stating that long-term repair of FRP tanks 

requires the use of proper repair materials and techniques. Commenters 

in favor of this position argued that only the manufacturer has the 

requisite knowledge of the appropriate materials and methods to repair 

the specific composition of FRP used in its tanks. They pointed out 

that these manufacturers have already established authorized

representatives trained in the proper methods and supplied with the 

quality-assured and correct materials. They also suggested that, 

because the manufacturer bears continuance of product liability, only 

the manufacturer's authorized representatives should be allowed to 

repair FRP tanks.

After carefully considering the arguments on both sides, 

EPA has decided to change the proposed requirement to allow not only the 

manufacturer's authorized representatives to repair FRP tanks but to 

also allow qualified in-house personnel to conduct repairs if a code of 

practice developed by a nationally recognized organization or 

independent testing laboratory is followed.

Information presented by commenters convinced the Agency 

that there are other qualified and competent individuals who could 

provide reliable and proper repair services for FRP UST systems. Though 

there are no currently established industry standard codes for repair of 

FRP tanks, at least one nationally recognized organization is presently 

developing such a code. Therefore, the Agency believes it would be 

imprudent to restrict repair services to only manufacturer's authorized 

representatives. The Agency also believes that allowing repairs to be 

conducted by other qualified in-house personnel in accordance with an 

industry code of practice will help ensure that there are adequate 

repair personnel available to provide competent repair services in a 

timely manner.
d. Vacuum Test

In § 280.33(d), EPA proposed requiring that a vacuum test 

(at 5.3 in. Hg) be performed on the tank following repair. Section 

280.33(f) proposed the added requirement of having a tank tightness test 

performed within one year following the repair of a tank. Comments were 

received on the technical details of these tests and on whether they 

were really needed to determine that the repaired tank was sound and 

would not release product to the environment. Several commenters 

questioned the technical adequacy and appropriateness of the use of a 

vacuum test, objecting to this requirement as possibly damaging some 

types of tanks.

As a result of the technical information supplied by these 

commenters, EPA agrees that release detection (see § 280.43(d)-(h) of 

the final rule), and quality control inspections performed according to 

established industry standards, should provide sufficient ensurance that 

the repair or lining of the tank was performed correctly, and thus, a 

vacuum test is not necessary. The current good performance of repaired 

tanks, most of which were not vacuum tested, points to the validity of 

these comments. In addition, EPA agrees that the test could be harmful 

in some cases. Consequently, the Agency has dropped the requirement of 

a vacuum test from the final rule.

EPA has also decided that the proposed requirement for a 

tank tightness test within one year following repair is not always 

necessary because it duplicates the industry practice of internally 

inspecting lined tanks and the release detection requirements that apply 

to the repaired tank. The good performance record of repaired tanks 

makes such an additional requirement unnecessary.

e. Pipes and Fittings (§ 280.33(c))

In § 280.33(e) of the proposal, EPA required replacement of 

pipes and fittings from which a release had occurred due to corrosion. 

The proposal did allow the tightening of loose fittings and joints for 

purposes of repairs. Comments were received indicating that FRP piping 

could be satisfactorily repaired and that some types of valves could

also be repaired adequately without replacement. EPA believes that 

replacement of metal pipe sections and fittings that released product 

because of corrosion or other damage is still necessary but, in response 

to the issues raised by several commenters, will allow repairs of FRP 

piping in the final rule. The final rule does not prohibit repairs of 

metal valves provided that these can be done in a manner that provides 

sufficient protection against releases. To ensure that these allowable 

repairs are carried out according to sound practice, EPA requires that 

all of the repaired sections be tested and shown to be tight so that 

they will not have a release after they are put back into service.
f. Recordkeeping (§ 280.33(f))

In § 280.33(g) of the proposal, EPA required owners and 

operators of a repaired tank to maintain records, including signed 

certification, capable of demonstrating compliance with the requirements 

of this section. 

Comments were received suggesting that a log should be 

required for each tank which would document installation, repairs and 

maintenance, products, tests, and results. EPA agrees that such a log 

would be a useful means for owners and operators to document their 

compliance with UST management requirements and would encourage it. EPA 

believes, however, that specifically requiring a log as opposed to other 

methods of recordkeeping is unnecessary. 

The final rule retains the general requirement that owners 

and operators maintain records demonstrating compliance with this 

section for the operating life of the UST system.

6. Reporting and Recordkeeping (§ 280.34)

a. Introduction

In the preamble to the proposal (52 FR 12711), the Agency 

identified the importance of the retention by the UST system owner and 

operator of key records of operation on site, and reporting of 

significant events to the implementing agency. Because routine 

reporting would create an overwhelming burden for the implementing 

agency due to the size of the large regulated universe, records will 

often be the only way for implementing agencies to determine that 

certain important regulatory actions actually took place. Such 

recordkeeping also prompts the owner and operator to carry out regularly 

scheduled actions that are necessary to protect human health and the 

environment. Reporting of significant developments (such as leaks and 

large overfills) provides information to implementing agencies early 

enough for them to ensure effective action is taken by owners and 

operators to correct the problem. In general, the proposal consisted of 

simple but essential recordkeeping and reporting requirements: 

recordkeeping that is sufficient to ensure each owner and operator can 

demonstrate the recent compliance status of the facility; and reporting 

that allows for early involvement of the implementing agency should an 

UST system failure need to be corrected.

The proposal required owners and operators to report three 

significant events to the implementing agency: (1) new UST system 

installation; (2) final closure; and (3) a suspected release from an UST 

system and any subsequent actions needed to contain, correct, and clean 

up a release. An UST system owner and operator who experiences no 

problems in the operation of the UST system would only have minimal 

reporting requirements, imposed at the installation and closure of the 

facility. Only in the event of system failure and a confirmed release 

would the reporting requirements substantially increase, and the level 
of this increase would be directly related to the significance of the 

threat posed to the environment. Recordkeeping was proposed that would 

demonstrate the use of requisite prevention and monitoring equipment as 

well as the facility's recent compliance status, as displayed through 

recent release detection, maintenance, and testing results.

Public comments on the proposal generally supported the 

Agency's proposed approach to recordkeeping and reporting although some 

concerns were raised about the scattered placement of these requirements 

throughout the rule. Some commenters stated that this format made it 

difficult for them to find and made it confusing to determine all of the 

owner and operator's recordkeeping and reporting responsibilities. In 

response to this concern, the final rule includes in one section of the 

rule (§ 280.34) a reference or directory to all of the reporting and 

recordkeeping requirements found elsewhere in the rule.

Other commenters suggested that additional and, in some 

cases, more complete records be required in the final rule. As 

explained below, however, today's recordkeeping and reporting 

requirements have remained essentially the same as were proposed. A few 

minor recordkeeping requirements have been added, and a few additional 

pieces of information must be reported during corrective actions to 

assist the implementing agency's assessment of the release problem. 

These few changes to specific recordkeeping and reporting requirements 

are discussed elsewhere in today's preamble as part of the more detailed 

analysis of the final rule's technical requirements for closure; release 

detection; tank system repair, operation and maintenance; and corrective 

action.

b. Summary of Final Approach

EPA received widespread support for the general notion that 

at least some recordkeeping and reporting is essential to ensure owners 

and operators adhere to the technical standards being promulgated today. 

EPA did not receive any information or comments to persuade it that a 

significant departure from the proposed approach was necessary or 

appropriate. Thus, the final rule essentially retains the proposed 

approach.

As discussed in the preamble to the proposal (52 FR 12712), 

recordkeeping is necessary to ensure compliance with the technical 

standards for release detection, closure, operation and maintenance of 

corrosion protection systems, and UST system repair. The Agency, as 

well as many commenters, believes, however, that demonstration of 

compliance of all requirements over the total operating life of the 

facility is impractical and unnecessary to protect human health and the 

environment. Today's approach is predicated on the intent to impose the 

minimum burden on the regulated community while at the same time 

ensuring that all owners and operators will be able to demonstrate at 

the request of the implementing agency whether their UST system is being 

managed in a manner that will protect human health and the environment. 

For example, the time frames for record retention were established to 

enable a demonstration of recent facility compliance status prior to an 
on-site visit. EPA is convinced that today's final recordkeeping 

requirements are essential and serve both the implementing agency's and 

regulated community's mutual interest. Many owners and operators may 

decide to keep more detailed records than are required or retain records 

for longer than today's minimum time frames. State and local 

governments may want to require additional recordkeeping.

Today's final reporting and notification requirements are 

also intended to foster the self-implementation that underlies today's 

final technical standards. Under today's reporting requirements, an 

owner and operator do not have any reporting obligations over the entire 

service life of the facility beyond the initial notification at 

installation and the final notification of permanent closure unless a 

suspected release in the environment has occurred. Given the enormous 

size of this regulated community, the Agency has concluded that it is 

impractical and unnecessary to overburden implementing agencies with 

periodic or routine reports from UST facilities that are operated 

properly and have no adverse environmental impacts. The Agency expects 

that most UST systems will rapidly improve and move into this category 

during the coming 10-year upgrade period.

Reporting of releases and corrective actions taken is 

explicitly required under section 9003(c) of RCRA. Although EPA expects 

numerous releases will be identified within this large regulated 

community, the Agency has concluded that reporting them to the 

implementing agency is a necessary first step to ensure protection of 

human health and the environment. Today's final approach to the 

reporting of releases and corrective action is based on the simple 

assumption that the more serious a release and its impacts are, the 

greater the necessity for interaction with (and reporting to) the 

implementing agency. The implementing agency is expected to ensure that 

the public interest is represented during cleanup decisionmaking and 

actual corrective action activities. The greater the threat to human 

health and the environment, the more reporting and governmental 

oversight that is needed.

Public comment on recordkeeping was generally favorable. 

Some commenters, however, objected to the differentiation between onsite and off-site record maintenance and availability. Under the 

proposal, records kept off-site had to be available within 24 hours 

while on-site records had to be immediately available. Other commenters 

objected to the requirement for providing off-site records within 24 

hours, noting that sometimes important records are retained at corporate 

headquarters far removed from the UST sites. EPA agrees that there 

should be no real distinction for availability of records and that the 

24-hour allowance may seem inequitable to those who must maintain 

records that are immediately available on-site. However, the provision 

in the final rule remains unchanged. Records retained at the site must 

be available immediately because EPA has concluded that there is no 

reason that they should not be except that they are not present or upto-date when requested. When records are maintained at a business 

office off-site, they must be located at a readily available site and 

provided upon request (§ 280.32(c)). This change to require off-site 

records to be provided "upon request" responds to those commenters who 
pointed out that the proposed 24-hour limit was often impossible to 

achieve when records are stored at off-site locations. This change is 

also made to provide some discretion to the on-site inspector who can 

talk to the owner and operator and determine where the records are 

stored off-site and decide whether they should be made available for 

inspection. If the records are easily accessible, the inspector may 

request that they be made immediately available. This change also 

responds to the commenter who believed there should be the same time 

allowed for providing records stored either on- or off-site because offsite records must be provided within the time frame requested by the 

implementing agency.

EPA believes that, under most circumstances, copies of the 

originals should be maintained on-site. If copies are not maintained at 

the sites, the owner and operator will have to take on the added burden 

of providing the implementing agency with these copies in an expedited 

fashion when they are requested.

Also, the Agency has determined that it will not make site 

plans a required record because it is not necessary to ensure compliance 

with the technical requirements promulgated today. A site plan is, 

however, a useful tool for owners and operators. The Agency notes that 

site plans are recommended in recent updates of national codes addressed 

to the installation of new UST systems.

Finally, as noted above, in response to commenters' 

confusion over the various recordkeeping and reporting requirements in 

the proposal, the final rule has been revised to include a directory in 

§ 280.34 that is intended to simply summarize and identify the 

recordkeeping and reporting requirements. This new section is intended 

to eliminate the confusion identified by several commenters when trying 

to locate their recordkeeping and reporting responsibilities in the 

proposal. Each item of reporting and recordkeeping is identified and 

listed, including a reference to the section of the final rule in which 

full details may be found. Requirements with respect to the general 

availability and maintenance of records are presented along with this 

directory section and have not changed since proposal, except for the 

slight extension of the allowable period for making off-site records 

available to the inspector (see discussion above).

D. Release Detection

This section of today's preamble provides a summary of the 

Agency's final approach to release detection, the proposed rule, and the 

major changes from the proposal. A section-by-section analysis of the 

final rule (IV.D.2.) discusses in detail the final release detection 

requirements, including highlights of major public comments received.
1. Overview

a. General Approach to Release Detection

As described earlier in this preamble, today's requirements 

that new and existing UST systems be properly installed, protected from 

corrosion, and equipped with spill and overfill protection will 

dramatically reduce UST system releases. Release detection is an 

essential backup measure to prevention, particularly for unprotected 

steel UST systems (prior to upgrading or replacement) and pressurized 

piping because they are more prone to releases. A variety of release 

detection methods have been successfully applied to USTs. These methods 

can be grouped into six general categories: tightness or precision 

tests, tank gauging systems, inventory control methods, ground-water 

monitoring, vapor monitoring, and interstitial monitoring. Each was 

discussed in the preamble to the proposal (52 FR 12714). State and 

local programs have chosen to rely on different combinations of these 

methods. They all appear to be successfully detecting releases when 

properly applied. To maintain flexibility in the selection of release 

detection methods, both for the implementing agencies and for the owners 

and operators, the proposal allowed the selection of release detection 

to be tailored to the characteristics of each site and, therefore, 

avoided unnecessary disruption of successful state and local programs. 

The most important features of the proposed and final rules are 

summarized in the sections below.

b. Highlights of the Proposed Rule

In the proposed rule, the release detection strategy relied 

on the use of either monthly detection methods or a combination of 

tightness testing (performed semiannually to every 5 years) and monthly 

inventory control. Frequent testing dramatically increases the 

probability of detecting a release and reduces the length of time a 

release can go undetected. A 30-day frequency was selected as a 

practical monitoring frequency that was sufficient to protect human 

health and the environment. The proposed rule required only one release 

detection method at each UST site, because frequent use of one 

monitoring method was sufficient to discover releases before they could 

cause significant damage to the environment.

Current industry practices generally do not include 

frequent release detection and most releases that are discovered are 

detected through impacts on the surrounding community or large inventory 

losses. Consequently, substantial time and effort will be required to 

reach the goal of monthly monitoring for all UST systems. The proposal 

phased in detection requirements over 5 years to allow the leak 

detection industry time to expand and to more evenly schedule the demand 

for detection equipment. The proposed rule also allowed less frequent 

use of tank testing (every 3 or 5 years when combined with monthly 

inventory controls) during the first 10 years of the program. The goal 
of the proposed approach was the installation of release detection as 

quickly as possible on the tanks most likely to leak.

To ensure flexibility, all proven methods of release 

detection were allowed in the proposed rule. In the absence of adequate 

data, the proposed rule did not set one performance standard for all 

release detection methods. Instead, each method was required to meet 

performance and design standards specific to that method. These 

standards were based on the experience of state programs that indicated 

these methods were effective under the specified conditions.

c. Major Changes in the Final Rule

Although the overall release detection strategy has not 

changed from the proposal, specific requirements on how and when release 

detection must be conducted have changed. The four most significant 

revisions to the proposed regulations include:

oMore frequent monitoring of existing unprotected tanks during 

the 10-year upgrade period;

o Less frequent monitoring of new and upgraded tanks until 

age 10;

o Gradual phase-in of release detection based on tank age; 

and

o More stringent requirements for pressurized piping.

These changes, discussed generally in section III.B. of today's 

preamble, are presented in detail in the appropriate parts of the 

section-by-section analysis below. Additional revisions made to the 

release detection requirements are also discussed in the section-bysection analysis.

In addition, three important organizational changes were 

made in response to commenters' concerns. First, in the proposed rule, 

the requirements for hazardous substance USTs were in a subsection of 

the petroleum UST requirements, and several commenters noted that they 

had difficulty finding and understanding the requirements for these 

systems. In response to this concern, the release detection 

requirements for petroleum and hazardous substance USTs have been 

separated in the final rule and placed in §§ 280.41 and 280.42, 

respectively.

Second, tanks and associated piping were treated in the 

proposed rule as a single unit. Each method of release detection 

applied to the tank was required also to detect leaks from piping. In 

another section of the proposed rule, there were additional release 

detection requirements that could only be applied to the piping. 

Commenters noted that this structure limited flexibility in meeting the 

release detection requirements by forcing the same method to be used for 

tanks and piping. They noted that the same method may not work for both 
tanks and piping and several viable detection methods for piping were 

excluded. In addition, the information on causes of release indicates 

that piping is generally a greater release threat than tanks. Thus, 

today's final rule treats piping separately from and with equal 

importance to the tank. The release detection methods for tanks and 

piping have been separated in the final rule into §§ 280.43 and 280.44, 

respectively.

Third, in the final rule, the release detection 

requirements for each type of UST system, including allowed methods and 

required frequencies of testing, have been consolidated into two brief 

sections (§§ 280.41 and 280.42). The detailed performance standards for 

each method of detection are now contained in §§ 280.43 and 280.44. The 

section-by-section analysis of the preamble parallels this structure so 

that all discussion of the phase-in schedule, the methods and 

combinations of methods allowed for each type of system, and frequencies 

of testing are discussed first (sections IV.D.2.a-c.). Discussion of 

research and public comments on the technical details of each detection 

method for tanks and piping is reserved for later sections (IV.D.2.de.).

2. Section-by-Section Analysis

a. General Requirements (§ 280.40)

(1) Use of One Release Detection Method.

In the proposed rule, a single release detection method 

could be used to meet the requirement to detect releases from both the 

tank and connected piping. As discussed in more detail in the preamble 

to the proposed rule (52 FR 12718-12719), the use of redundant methods 

of release detection was not required at each UST site because the 

Agency was not convinced that the required use of these "backup" methods 

would provide significant environmental gains in comparison to the 

adverse impacts on program implementation. Some commenters opposed 

allowing only one method of release detection primarily because they 

believe all the methods are unreliable and insufficiently developed, 

particularly external methods. Other commenters, however, agreed with 

EPA's position on this issue and cited their own satisfactory experience 

with the various methods.

The final rule continues to allow the use of a single 

properly installed and operated release detection method for tanks when 

testing is performed monthly. When less frequent monitoring is used it 

must be backed up by use of monthly inventory control. Owners and 

operators remain free to use multiple methods if they desire, and state 

and local programs can require redundant systems.

EPA decided against requiring multiple methods because 

frequent use of a single detection method, when combined with the 

prevention measures contained in other sections of the rule, is 
sufficient to protect human health and the environment. The performance 

standards, design criteria, and limitations on the methods contained in 

the rule are intended to ensure that the optimum performance of each 

release detection method is achieved. Repeating the test monthly 

dramatically reduces the possibility of failing to detect a leak. Each 

test serves as a separate check of the integrity of the UST system. 

Field reports confirm the success of single methods in detecting 

releases from UST systems. For example, Dade County, Florida, has 

detected over 350 releases using ground-water monitoring wells. EPA's 

research on the best ways to use some of the different release detection 

methods is directed towards improving the field performance of various 

types of methods. For tanks and suction piping systems, one detection 

method, combined with prevention efforts, should virtually eliminate 

undetected releases.

The Agency chose not to rely on one method of detection for 

pressurized piping, however. Even with good efforts at prevention, 

these systems may still result in significant releases. Consequently, 

the final rule requires existing and new pressurized lines to use both 

automatic line leak detectors and another leak detection method (either 

monthly monitoring or annual line tightness tests).

(2) Scope of Release Detection (§ 280.40(a)(1)).

The proposed rule provided a general requirement that the 

release detection method be "capable of detecting a release from any 

portion of the UST system." The purpose of this requirement was to 

ensure detection of both tank and piping leaks. A few commenters 

objected to the general nature of the wording of the requirement because 

it includes some portions of the UST system such as vent lines, fill 

pipes, and bungs on the top of the tank that do not normally contain 

regulated substances. Some tank tightness test methods do not test the 

top of the tank and, thus, do not detect the presence of holes in the 

vents and bungs. These portions of the tank only leak when the tank is 

overfilled.

EPA shares the concern of commenters that a strict 

interpretation of the wording in the proposed requirement could result 

in some release detection methods, particularly non-overfill tightness 

tests, not being allowed because they cannot detect releases from 

portions of the UST system that do not normally leak. The final rule's 

wording that the methods must be able to detect a release from "any 

portion of the tank and the connected underground piping that routinely 

contains product" is intended to make clear that tank tightness test 

methods that do not overfill the tank can be used, as long as they meet 

the other applicable performance standards and another acceptable method 

is used to test or monitor the piping.

Furthermore, releases from the top of the tank or vents 

occur during overfills, which are not a normal operating condition. 

Prevention of overfills is addressed in § 280.20(c), § 280.21 (d), and 

§ 280.30, which together require that all new and upgraded tanks have 
overfill prevention equipment and spill catchment devices and that 

proper filling procedures be followed to prevent these "nonoperational" 

releases. These requirements are intended to prevent these types of

releases; thus, EPA does not believe methods of release detection must 

be used that will detect them.

The additional information on causes of release that EPA 

has collected since the proposal (see section II.F. of this preamble) 

reinforces the fact that piping is a major source of releases. 

Therefore, the final rule continues to require that the methods of 

release detection that are used must be capable (either singly or in 

combination) of detecting a release from both the tank vessel and the 

piping that conveys product.

(3) Installation, Operation, Calibration, and Maintenance 

(§ 280.40(a)(2)).

To ensure that the release detection method will reliably 

detect releases once in place, the proposed rule required installation, 

calibration, operation, and maintenance according to manufacturers' 

specifications. At proposal, the Agency decided against requiring 

certification of installers and servicers of release detection equipment 

because these programs are not currently developed and there are other 

effective approaches for ensuring proper installation (52 FR 12719). As 

discussed below, commenters stated that the rule should require 

certification of installers and servicers of release detection 

equipment. After consideration of these comments, EPA continues to 

believe that such a requirement would hinder rapid installation and 

flexibility in designing effective ways to regulate installers. Today's 

final rule will remain as proposed for the reasons discussed below.

The UST release detection field is a new and proliferating 

area of technology, and, because of this, some commenters suggested that 

a certification program should be required for installers and operators 

of release detection equipment to ensure high quality work and to assist 

owners and operators in selecting qualified personnel. Certification by 

EPA or state agencies was suggested. Other commenters felt that a state 

or federal certification program would limit the number of installers, 

would increase the cost of release detection provided by those 

installers who were already certified, and would delay widespread 

application of release detection methods. Some of these commenters 

suggested alternatives to state or federal installer certification.

By including the performance standard in the proposed rule, 

EPA acknowledged that ensuring proper installation and operation of 

equipment is important. Although a certification program is a viable 

approach to achieving this goal, EPA disagrees with commenters who felt 

that state or federal certification is the only way to ensure quality 

installations. Existing state programs that lack certification programs 

have been effective at discovering releases. As commenters noted, there 

are numerous possible approaches to ensure proper installation. 

Mandating certification would unnecessarily restrict states from 

designing alternative effective ways to regulate installers.
EPA agrees with commenters that the time required to 

conduct a certification program would seriously hinder rapid 

implementation of release detection. Installing leak detection quickly 

on existing tanks, which are primarily unprotected steel, will be of 

significant environmental benefit, even in the absence of certification. 

For these reasons, no additional requirements have been included in the 

final rule to ensure release detection installation and operation.

(4) Meeting the Performance Standards (§ 280.40(a)(3)).

In the proposal's preamble (52 FR 12714-12718), the Agency 

described three possible approaches to ensure the quality of release 

detection equipment used to meet the regulations. EPA solicited 

comments on a general performance standard, certification of methods, 

and a method-specific performance standard. The Agency proposed the 

method-specific approach because it offered the greatest flexibility and 

facilitated rapid program implementation. Commenters generally agreed 

with the advantages and disadvantages ascribed to each approach, and 

many concluded that the method-specific approach is the best possible at 

present. The final rule thus retains method-specific standards by 

requiring each method used meet the standards in § 280.43 or § 280.44.

Commenters generally agreed with both the explanation and 

the conclusion in the proposal preamble concerning the use of methodspecific release detection standards. Many commenters believe that the 

method-specific approach would be the most realistic approach given our 

current knowledge and that it would allow the widest range of choices 

among effective technologies. Some commenters, however, believed a 

general standard should be formulated based on the standard specified 

for tank tightness testing (0.1 gallon per hour). Because the methodspecific standard would allow varying performance standards, these 

commenters felt that many owners would simply select the cheapest, least 

effective method. Other commenters recommended a certification 

approach, feeling that consistency was less important than ensuring that 

the regulated community knew exactly what devices met the standards.

The preamble to the proposal contained an extensive 

discussion of the merits of each of the three approaches to regulating 

release detection. One approach considered by the Agency was to specify 

a general standard for the leak rate or quantity which must be detected 

by a method and not specify individual methods or restrictions on their 

use. This approach was viewed as providing the most consistent level of 

performance and the one that best challenged manufacturers to develop 

defensible performance claims for their equipment. This approach is not 

used in the final rule for two reasons. First, the Agency does not have 

sufficient information to relate leak rates to the quantity of product 

detected by external methods under all possible site conditions. 

Second, eliminating the specific methods in the rule would slow program 

implementation by forcing owners and operators to wait for detailed, 

extensive performance information before conducting release detection. 

The final rule, however, incorporates the flexibility of a general 

performance standard by allowing, in addition to specific methods, any 
method which can detect a 0.2 gallon per hour leak rate with a 

probability of detection of 0.95 and a probability of false alarm of 

0.05 within a month. For a discussion of this addition, see section 

IV.D.2.a.4. of today's preamble.

A certification approach applied at the federal level would 

provide the regulated community with the clearest direction concerning 

which release detection equipment was acceptable. This approach is not 

used in the final rule because it would slow program implementation and 

reduce the choices available to owners and operators over the next 

several years. Further, it was not viewed as necessary because 

comparable performance information for each method can be generated by 

private efforts without federal involvement.

Research results and data submitted by commenters after the 

proposal have reinforced the Agency's belief that all of the methods 

that were proposed are effective release detection techniques if used 

within the context of certain constraints (discussed in the section on 

individual methods). EPA believes that offering a broad selection of 

methods will make it easier for owners and operators to comply with the 

regulation. Also, a broad selection is consistent with the 

encouragement of existing industry trends and state programs, which have 

utilized a variety of release technologies and which have been proven 

effective at discovering leaks. Information gathered by EPA suggests, 

but does not conclusively prove, that all of the methods included in the 

rule can detect at least a 0.2 gallon per hour release within 30 days 

when used in accordance with the restrictions on that method. The 

Agency believes that all methods will eventually be able to prove they 

reliably detect 0.2 gallon per hour releases and has included that as a 

standard for approving new methods. This standard is discussed in 

section IV.D.2.a.4. Allowing a range of methods with specific standards 

does not mean the cheapest, least effective method will be selected, 

because cost and effectiveness are not necessarily related. For 

instance, under some site conditions (e.g., ground water within the 

excavation zone), manual ground-water sampling may be the cheapest 

method and will reliably detect releases substantially smaller than 0.2 

gallon per hour.

(5) Delay in Detection Probabilities (§ 280.40(a)(3)).

As discussed in the proposal preamble (52 FR 12719), a 

complete release detection performance standard includes not only the 

leak rate or quantity that a method must detect, but also the 

probabilities of detection (PD) and false alarm (PFA). In the proposed 

regulations, complete standards of this type were included for in-tank 

detection methods in the section on specific methods. Research results 

and commenters' concerns have caused the Agency to make several 

important changes in the final rule. The probabilities have been moved

to the general requirements section (§ 280.40(a)(3)) and changed 

slightly, and the effective date has been delayed for two years. These 

changes are discussed below.
The proposal preamble emphasized the statistical nature of 

detecting leaks and the large number of variables that add to the 

uncertainty in declaring a leak. The probability of detecting a leak is 

dependent on its size. All methods are more likely to discover large 

leaks than small ones. With regard to detecting the smallest leaks, the 

Agency recognized that good methods properly operated may mistakenly 

declare a leak when none exists (false alarm) or fail to discover some 

leaks (missed detection). Consequently, the standards for tank 

tightness testing and automatic in-tank monitoring included the 

requirement that methods detect a specified leak rate with a PD of 0.99 

and a PFA of 0.01. The Agency remains convinced that specifying 

probabilities in this manner better defines the performance standards 

and should help owners and operators make informed choices about leak 

detection.

The final rule retains the PD and PFA as part of the leak 

detection performance standard. The probabilities have been removed 

from the standards for specific methods and placed in the general 

requirements section. This change expands the coverage of the 

probabilities to include automatic line leak detectors and interstitial 

monitors as well as tank and line tightness tests and automatic in-tank 

monitors. The Agency made this change to clarify that all leak rates or 

quantities specified as part of a method-specific standard in § 280.43 

or § 280.44 must be detected with the same level of reliability.

The proposed rule set the PD at 0.99 and the PFA at 0.01. 

In the final rule, the PD has been changed to 0.95, and the PFA has been 

changed to 0.05. The Agency made this change for several reasons.

First, the Agency is not convinced that the 0.99/0.01 

specification was a realistic standard given the wide range of variables 

affecting leak detection results. EPA's study of tank testing methods 

has attempted to determine performance at this level of precision and 

only 2 methods of the 25 studied could meet the standard. No study of 

this sort has been undertaken for the other methods covered by the 

probabilities in the final rule. Further, EPA does not plan to conduct 

studies similar to the one for tank tightness testing for other leak 

detection methods. Rather, the Agency intends that manufacturers should 

evaluate their methods to prove they meet the standard in the rule. 

Thus, the change in the final rule will encourage manufacturers to 

undertake this research. EPA is developing procedures for testing 

release detection equipment in a common way to help manufacturers in 

evaluating their equipment. EPA chose the 0.95/0.05 specification in 

the final rule because it is a level of performance attained by a 

modified commercial tank test method in the National Motor Fuel Survey. 

In addition, several commenters felt that a probability of detection of 

0.95 was more realistic and was adequate to protect human health and the 

environment.

Because the final rule requires frequent-to-continuous 

monitoring, the change in probabilities will have little environmental 

impact. For example, a test which detects 0.1 gallon per hour leaks 95 

percent of the time in one test will discover 99.9 percent of 0.1 gallon 

per hour leaks in 3 consecutive tests. Further, tests that meet this 
standard are virtually certain to detect leaks larger than this 

threshold and will detect a significant number of leaks below the 

threshold. Under either standard, large leaks will be caught 

immediately and small leaks will be discovered before they cause 

environmental damage.

The final change in this section of the final rule is a 

delay in the effective date of the probabilities. As discussed above, 

few methods have been proven to meet the complete standard specified in 

the proposed rule. However, preliminary results from the EPA's tank 

testing study (Notice of Availability; 53 FR 10403) indicate that

several methods could meet the standard with simple changes in 

procedures and equipment. The Agency also wanted to allow time for 

manufacturers of automatic tank gauging systems, automatic line leak 

detectors, and interstitial monitors to prove that their systems meet 

the complete standard. The Agency believes manufacturers can make the 

necessary changes to their methods and evaluate their performance in 2 

years. Until the probabilities become effective, methods need only 

detect the leak rate or quantity specified for that method in § 280.43 

and § 280.44. Methods installed or conducted during this 2-year phasein will not need to be performed again or replaced after the 

probabilities become effective, but all methods used after that period 

of time will have to achieve the probability standard.

(6) Reporting of Positive Monitoring Results (§ 

280.40(b)).

The proposed rule contained a provision in Subpart E that 

the owner and operator must report all suspected releases indicated by 

the results of release detection monitoring. Perhaps because this 

release detection reporting requirement was in a different subpart from 

the release detection technical requirements, commenters stated that it 

was unclear when a suspected release needed to be reported. To clarify 

and strengthen the requirement to report all suspected releases, a 

provision has been added to Subpart D (§ 280.40(b)) in the final rule 

explicitly stating that any indication by the release detection method 

that a release has occurred must be reported in accordance with 

reporting procedures described in Subpart E.

It is intended that all release detection equipment be 

operated at least at the level of sensitivity indicated in the 

performance standard. For example, 2 years after the effective date of 

the rule, the tightness test threshold (i.e., test result that indicates 

a suspected release) should be set to detect 0.1 gallon per hour leak 

rates with a PD of 95 percent and a PFA of 5 percent; this threshold 

value may differ for various tightness testing devices. Manufacturers 

of the release detection equipment must determine what this threshold 

value must be to meet the performance standard and inform operators of 

their equipment. Until the manufacturer sets such a threshold, tank 

test operators should continue to use the current 0.05 gallon per hour 

threshold. For most tank testing methods, this will approximate the 

threshold level for detecting 0.1 gallon per hour leaks. The owner and 

operator would report a suspected release when a test result exceeds 
0.05 gallons per hour or the threshold value provided by the 

manufacturer in accordance with § 280.50.

It is important to note that the performance standards such 

as 0.2 gallons per hour or 1/8 inch of product on top of the ground 

water are device performance standards set to exclude less effective 

equipment. The standards are not allowable contamination levels. 

Owners and operators are still responsible for correcting leaks and 

cleaning up any product released to the environment. It is in their 

interest to use the most effective release detection equipment and 

operate it so the device detects releases as quickly as possible to 

avoid potentially costly corrective action.

(7) Phase-in of Release Detection (§ 280.40(c)).

The proposed rule required a 3- or 5-year phase-in of 

release detection, with the shorter phase-in period applied to USTs 

without protection from corrosion and the longer phase-in to those USTs 

with corrosion protection. These phase-in periods were based, in part, 

on the experiences of several state and local UST programs in initiating 

release detection under a phase-in schedule that was typically 3 to 5 

years (52 FR 12677, 12703-12704). This phase-in was proposed to ensure 

that tanks with the greater risk of leaking (those unprotected from 

corrosion) had release detection installed first. As discussed in the 

proposal preamble, the total phase-in period covers 5 years to allow 

enough time for the release detection industry to respond to the demand, 

owners and operators of existing tanks to plan their needs, and 

implementing agencies to develop their programs. The proposed rule also 

required closure of existing USTs that could not meet the phase-in 

schedule.

Commenters recommended a variety of phase-in periods and 

generally recommended age as the most appropriate basis for the phasein. Therefore, § 280.40(c) of the final rule phases in the 

implementation of release detection over 1 to 5 years based on the age 

of the system (oldest tanks first). Requiring the oldest tanks to phase 

in release detection sooner, within 1 year, ensures that those UST 

systems most likely to leak are addressed first. The final rule also 

retains the proposed requirement of closure of any USTs that cannot meet 

the release detection requirements by the phase-in date. A significant 

addition to the final rule is the requirement that existing systems with 

pressurized piping must retrofit line leak detectors within 2 years. 

Comments received regarding the phase-in of release detection are 

discussed in more detail below.

Commenters recommended a range of time periods from 3 to 10 

years for completing the phase-in of release detection. Commenters 

supporting a longer period believed that the proposed phase-in periods 

would overburden the release detection industry, resulting in poor 

quality installations and late compliance, and cause economic hardship 

to owners and operators. Those commenters recommending shorter phase-in 

periods believed that a tighter schedule would prevent significant 

environmental damage. The Agency has decided in the final rule to 
retain the overall 5-year phase-in time period for the same reasons 

outlined in the proposal preamble (52 FR 12677, 12703, and 12704). 

Based on experience at the state and local level, EPA does not believe 

release detection can be installed and conducted at over 700,000 UST 

sites nationwide in less than 5 years. Not only will it be difficult to 

do in less than 5 years, but some of the release detection systems 

installed on a more expeditious timetable could be lower quality as a 

result. As discussed above, however, the greatest release potential 

will be during this interim period. Thus, lengthening the phase-in 

period would result in unacceptably greater environmental damage. 

Moreover, even accepting commenters' concerns about economic burdens, 

lengthening the phase-in would not provide a resolution because 

retrofitting would still be necessary ultimately and would be coupled 

with greater corrective action costs brought on by the delay in 

detection. For these reasons, today's final rule retains the 5-year 

phase-in period.

During the 5-year phase-in period, it is important to 

direct release detection efforts at the existing UST systems most likely 

to leak. Many commenters recommended achieving this goal by phasing in 

release detection based on the age of the UST system. They pointed out 

that this approach also has the advantage of stabilizing the demand for 

release detection, resulting in less burden for both the release 

detection industry and the owners and operators. It also has the 

advantage of addressing first the tanks that are most likely to leak. 

Several commenters pointed out their concerns that if the phase-in is 

not sequenced in its implementation, the regulated community will 

collectively wait until the last minute, and unavoidable further delays 

will ensue. A few commenters opposed an age-based schedule because it 

was too simplistic or ignored other important factors.

The Agency agrees with commenters suggesting a release 

detection phase-in schedule based on age. Although age is not the only 

factor in determining when a tank will leak, it is an important factor 

that is readily understood and determined and, therefore, easy to 

implement. This approach is already being used successfully in several 

state and local programs. The approach in the final rule is not a 

radical departure from the proposed phase-in schedule. The causes-ofrelease study indicates that most existing protected USTs are less than 

10 years old. Under both the proposed and final phase-in schedules, 

these tanks must phase in release detection within 5 years after 

promulgation. EPA believes that the main impact of the revised schedule 

will be to spread out the phase-in of release detection on unprotected 

USTs, which represent over 75 percent of UST systems, over years 1 

through 4 rather than require it all at year 3, resulting in fewer 

implementation bottlenecks.

Some commenters recommended a class approach (sensitive 

areas first) to phasing in release detection. Although the concept of 

retrofitting release detection in vulnerable areas first is appealing, 

EPA does not believe it is possible to identify sensitive classes in any 

meaningful way at the federal level (see section III.C. of this 

preamble). States can choose to phase in release detection based on a 

class approach without losing the ability to receive state program 
approval (see § 281.33) if they complete a phase-in of release detection 

at all existing tanks within 5 years and pressurized piping in 2 years.

EPA's information on the causes of release clearly 

indicates that pressurized piping represents a major source of 

uncontrolled releases. None of the requirements for existing systems in 

the proposed rule addressed the threat of catastrophic releases from 

pressurized piping. Consequently, in the supplemental notice (52 FR 

48638), the Agency requested comment on the idea of requiring existing 

systems to retrofit line leak detectors on pressurized piping. 

Commenters generally felt that it was appropriate to require such a 

retrofit and recommended a variety of phase-in schedules. EPA agrees 

with commenters who recommended a short phase-in schedule because this 

piping is a significant environmental hazard, retrofitting line leak 

detectors is relatively easy and inexpensive, the devices are highly 

effective (see section IV.D.2.e.1. of the preamble), and many systems 

are already equipped with the devices. Consequently, the final rule 

requires that existing pressurized piping meet the same standards as new 

piping 2 years after the effective date of the rule (see section 

IV.D.2.b.2. of the preamble for piping requirements).

(8) Closure if Release Detection Is Not Installed 

(280.40(d)).

In the proposed rule, EPA required closure of an existing 

UST system if a method of release detection was not installed by the end 

of the specified phase-in period. Most existing USTs are not protected 

from corrosion and, thus, are likely to corrode and eventually leak. 

The selected phase-in schedule discussed above is considered the maximum 

time that these systems should be allowed to operate without release 

detection. Therefore, the final rule continues to require that UST 

systems be closed if release detection cannot be retrofitted or applied 

by the phase-in date.

One commenter noted that the closure procedures of the 

proposed rule required a site assessment of the excavation zone before 

closure, the results of which might delay closure beyond the allowable 

time frame. Although the Agency recognizes that closure can be a timeconsuming process, it should not require any more time than the 

selection and installation of release detection equipment. The final 

rule requires that, by the phase-in date, the owner must remove the tank 

or fill it with inert material and complete the site assessment. Should 

a release be discovered, responding to the findings of the site 

assessment is part of corrective action and need not be completed by the 

phase-in deadline. Owners and operators are expected to plan ahead to 

ensure that they complete installation of release detection or the 

closure procedures by the specified date. This will allow the 

implementing agency to ensure compliance with both requirements with a 

single inspection. For these reasons, EPA has retained in the final 

rule the provision to complete closure by the end of the phase-in 

period.
(9) Other Changes.

One of the general requirements in the proposed rule 

required a site assessment prior to the installation of any external 

leak detection system to ensure compliance with the performance 

standards for the particular method used. To clarify that the site 

assessment is intended to include only an analysis of selected factors 

within or beneath the excavation zone, the general requirement has been 

deleted, and the only assessment requirements are contained in 

§§ 280.43(e)(6) and (f)(7) of the final rule. These changes are 

discussed below. 

The importance of a site assessment in correctly selecting 

and applying an external method was discussed in the proposal preamble 

(52 FR 12720-12722). Although numerous factors were listed in the 

proposal preamble concerning a site assessment, EPA stressed that the 

assessment should, at a minimum, ensure compliance with the methodspecific restrictions in the proposed rule. EPA requested comment on 

the proposal to include these or other site variables in the assessment 

requirement. Some commenters stated their belief that a complete site 

assessment is too extensive a technique to be required for demonstrating 

the performance of external release detection and does not provide much 

useful information because conditions at the site change constantly. 

Most commenters, however, agreed that a site assessment is appropriate 

before installation of external release detection systems. In fact, 

these commenters wanted to extend this provision by requiring site 

assessments for all release detection methods, thereby requiring a quick 

national survey of all UST site conditions. Others suggested at least 

requiring a site assessment periodically at all USTs.

The Agency continues to believe that site assessment of the 

excavation zone is necessary to ensure the reliability of external 

methods. The Agency also agrees with comments stating that the site 

assessment requires no more information beyond checking a site for 

compliance with the restrictions on the methods. Conditions in and 

below the excavation zone must be known before an external method is 

selected or installed because inappropriate excavation conditions can 

render some external methods ineffective. Internal methods are not 

typically affected by site conditions, and those methods that are 

affected (e.g., water table level can affect tightness tests) can 

account for these conditions without performing a site assessment. The 

major factors determining the effectiveness of ground-water and vapor 

monitoring were included in the method-specific performance requirements 

in the proposed rule, and, for most sites, an adequate assessment will 

require evaluation of only those factors.

The Agency decided against requiring a more extensive, more 

frequent, or a more widely applied site assessment because of the 

unnecessary burden it would place on implementing agencies and the 

possible delays in release detection compliance it would cause. The 

Agency believes that the greatest benefit for existing systems, short of 

upgrade or replacement, will be obtained by conducting release detection 

as quickly as possible. The site assessment for certain external 

methods is retained in the final rule in §§ 280.43(e)(6) and (f)(7) 
because EPA believes it is important to ensure that these methods work 

properly. The site assessment is not intended to be a general search 

for contamination at the site. Any contamination found, however, must 

be reported, and the owner and operator must comply with the corrective 

action requirements of Subpart F. A more detailed search for 

contamination is required when tanks close under Subpart G.

b. Requirements for Petroleum UST Systems (§ 280.41)

(1) Requirements for Petroleum Tanks (§ 280.41(a)).

(a) Overview. The proposed rule offered a variety of 

release detection methods for petroleum UST systems. New or existing 

UST systems could perform accurate monthly monitoring using automatic 

tank gauges, vapor monitors, ground-water monitors, interstitial 

monitors, or other methods approved by the implementing agency. The 

proposal allowed two exceptions to the monthly monitoring requirement. 

First, when combined with monthly inventory control, tank tightness 

tests could be performed semiannually at new UST systems. The proposal 

allowed semiannual tightness testing and inventory reconciliation for 

new tanks because the combination was believed to be as accurate as 

monthly monitoring. Second, when combined with monthly inventory 

control, tank tightness tests could be performed less frequently at 

existing USTs during the 10-year upgrade period (every 3 years for bare 

steel systems or every 5 years for protected tanks). Less infrequent 

tank tests for existing USTs were permitted during the phase-in period 

because the Agency believed the release detection industry lacked the 

capacity to perform monthly monitoring at all existing tanks in 3 to 5 

years.

The use of monthly monitoring methods has been retained as 

an option for all petroleum UST systems in the final rule. The final 

rule also contains two exceptions for tightness testing similar to those 

in the proposal. An overview of the release detection requirements is

presented in Figure 4. During the 10-year upgrade period at existing 

tanks that are not adequately protected from corrosion and lack spill 

and overfill equipment, the rule now requires either (1) annual tank 

tests and monthly inventory controls or (2) monthly monitoring. Tanks 

that meet the standards for new or upgraded tanks are required either 

(1) to conduct tank tests every 5 years combined with monthly inventory 

controls for a 10-year period following the date of installation or 

upgrade or until 1998, whichever is later, or (2) to conduct monthly 

monitoring. Also, in both cases, by the end of the 10-year period, 

these USTs must be using an approved monthly monitoring method.

[INSERT FIGURE 4 HERE.]

(b) Monthly monitoring. In the proposal preamble, EPA 

discussed a variety of possible release detection strategies ranging 

from continuous monitoring to an infrequent "check" of the tank system 
(52 FR 12676-12677). "Frequent-to-continuous" detection methods were 

proposed by the Agency because more frequent sampling improves the 

chances of finding leaks and limits the length of time over which leaks 

can progress unchecked. As a result, the proposal required tanks to be 

monitored at least monthly unless the owner or operator chose an option 

that included less frequent tank tightness testing in combination with 

monthly inventory control. (Monthly inventory control does not by 

itself meet the requirements for "monthly" monitoring and must be 

combined with periodic tightness testing.)

Commenters were divided over whether monthly monitoring 

provides adequate environmental protection and whether it was unduly 

burdensome. EPA continues to believe that the monthly monitoring 

frequency offers effective environmental protection. Moreover, checking 

the release detection equipment once a month is not difficult or 

expensive, according to several commenters and Agency research. More 

frequent monitoring would necessitate the use of continuous monitors, 

which are not needed at all sites and which may be less effective at 

some sites. Thus, the final rule (§ 280.41(a)) requires monthly 

monitoring as a baseline for all new and existing petroleum UST systems.

(c) Tank Tightness Testing and Inventory Control 

(§ 280.41(a)(2)). In the preamble to the proposal, EPA noted practical 

problems with conducting monthly monitoring at all existing tanks over 

the proposed phase-in period. These methods have not been practiced on 

a mass scale in the past, and the Agency expressed the concern that the 

industry did not have sufficient capacity to capably install monthly 

monitoring at 1.4 million USTs in 5 years. Because tank tightness 

testing and inventory control are commonly used as effective release 

detection methods not requiring the installation of permanent equipment, 

EPA allowed these methods as options for existing USTs during the 10-

year phase-in period for upgrading (see section IV.D.2.b.1).

The large number of existing systems to be tested and the 

limited industry capacity caused the Agency to propose less frequent 

tank testing for existing systems than for new systems: every 3 years 

at unprotected existing systems and every 5 years at protected existing 

systems. The proposed frequencies were selected in recognition of the 

differing probability of releases at unprotected and protected UST 

systems. For new tanks, the proposal allowed monthly inventory control 

combined with semiannual tightness testing because the combination was 

believed to be as effective as monthly monitoring using the other 

approved methods.
Many commenters were concerned about the use of tank 

tightness testing and inventory control as an alternative to the monthly 

monitoring requirements. Commenters particularly questioned the 

appropriateness of more frequent monitoring being proposed for new tanks 

than for existing unprotected tanks. Although there was a variety of 

opinions on what the proper frequencies were, commenters uniformly felt 

that new tanks were less likely to leak and should be monitored less 

often than existing tanks. The new information presented in the "Causes 

of Release Study" corroborates these concerns that the most serious 

environmental threat is posed by older, unprotected steel tanks (see 

section II. F. of the preamble). Available evidence demonstrates that 

new or upgraded tanks are extremely unlikely to leak over their normal 

operational lifetimes especially within 10 years of installation or 

upgrade. EPA solicited comments on this issue and this new information 

in the supplemental notice published December 23, 1987 (52 FR 48641-

48642). Most commenters agreed with the Agency's conclusions on these 

matters, which are reflected in the final rule.

The Agency continues to believe that monthly monitoring 

cannot be installed on all UST systems within 5 years and that allowing 

tightness testing combined with inventory control will ensure that 

release detection can be provided to all existing USTs as soon as 

possible. During the phase-in period, EPA believes that priority should 

be given to requiring application of available release detection 

resources to older bare steel systems. Accordingly, in § 280.41(a)(2), 

the final rule requires that if owners and operators of existing 

unprotected UST systems choose tightness testing, it must be performed 

yearly rather than every 3 years as proposed. Existing protected 

systems (with spill and overfill prevention equipment) are required to 

be tested every 5 years during the 10-year upgrading period, the same as 

proposed. Because extremely few new or upgraded tanks are expected to 

leak during the first 10 years of their operational life, under the 

final rule (§ 280.41(a)(1)), these tanks may also conduct tightness 

testing every 5 years. This approach has the advantage of encouraging 

upgrade or replacement of unprotected tanks before the end of the phasein period, resulting in improved environmental protection. At the end 

of the 10-year upgrading period or at the end of the 10-year operational 

life of new or upgraded systems, these tanks must be equipped with a 

monthly monitoring method.

The proposed rule required tank tightness testing to be 

combined with inventory control (or another method of equivalent 

performance) for several reasons. Frequent tank tightness testing is 

not practical because it requires extensive preparation, including a 

shutdown of operations. It is, however, a sensitive method that 

provides very accurate results. Manual inventory control is less 

sensitive but can provide nearly continuous (daily) release detection 

that can reliably detect larger releases. The rule proposed the 

combination of the two techniques to compensate for each component's 

disadvantages. Several commenters on the proposed rule viewed the 

combination of techniques as redundant and stated that each method is 

adequate on its own. Other commenters agreed that, separately, each of 

these techniques would be an inadequate release detection method.
The Agency evaluated different approaches to tank tightness 

testing and inventory control since the proposal (Notice of 

Availability; 53 FR 10403). The results of the studies, which are 

discussed in more detail in the preamble section on these methods, 

confirm that monthly inventory control is effective at reliably 

detecting larger leaks (about 1 gallon per hour) and that tank testing 

can reliably detect much smaller leaks (0.1 gallon per hour). This 

research and information submitted by commenters convinced EPA to retain 

the combination of infrequent tank testing and monthly inventory control 

in the final rule as an exception to monthly monitoring in certain 

situations.

The proposed semiannual tightness testing and inventory 

control for new USTs has been deleted from the final rule, because the 

Agency does not believe that the combination is as effective as the

other monitoring methods. The Agency continues to believe that monthly 

monitoring is necessary to protect human health and the environment; 

less frequent monitoring is allowed only as an interim measure. 

Currently, conducting monthly tank tightness testing is not a practical 

or economical method. Tank testing methods may be developed in the 

future, however, that can be performed on a monthly basis to detect 

leaks of 0.2 gallon per hour. The final rule allows the use of this 

method without inventory control once the method is proven to meet the 

performance standard in the section on other methods (§ 280.43(h)).

(d) Manual Tank Gauging (§ 280.41(a)(3)). In addition to 

the other release detection methods in the proposed rule, the final rule 

also includes manual tank gauging. The Agency requested comment on the 

use of this method in the supplement to the proposed rule (52 FR 48641), 

citing a study submitted by a commenter on the proposal showing that 

this method was effective for used oil tanks. EPA conducted an analysis 

of this study (Notice of Availability; 53 FR 10403) and found that 

weekly tank gauging can detect 0.2 gallon per hour leaks with a PD of 95 

percent and a PFA of 5 percent for tanks smaller than 550 gallons.

Because it provides the same level of protection as other 

monthly monitoring methods, the final rule allows use of this method for 

any tank with nominal capacity of 550 gallons or less. Detailed 

discussion of research and comments on the inclusion of this method is 

provided in Section IV.D.2.d.(2). of today's preamble.
(2) Requirements for Petroleum Piping (§ 280.41(b)).

(a) Overview. The proposed regulation required that each 

release detection method chosen for the tank also detect releases from 

the piping. In addition, new pressurized piping was required to have 

equipment capable of detecting and shutting off a release of at least 2 

gallons per hour unless the piping had continuous or interstitial 

monitoring. Suction piping that meets certain minimum design 

specifications was exempt from these release detection requirements.

Commenters agreed that pressurized piping was allowable but 

that additional release detection requirements were necessary. Some 

commenters had reservations about automatic shutoff devices and flow 

restrictors and recommended backup release detection or double-walled 

piping. New information acquired by the Agency since proposal on causes 

of release indicates that pressurized piping, along with spills and 

overfills, is the major source of releases, particularly large-volume 

catastrophic releases (see section II.F. of this preamble). Because of 

this new information, the Agency requested additional comment on release 

detection issues related to underground piping in the supplemental 

FEDERAL REGISTER notice published December 23, 1987 (52 FR 48641-48642).

The final rule has been revised to reflect the importance

of preventing and rapidly detecting piping releases by including 

additional release detection requirements for pressurized piping and 

further encouraging the use of suction systems. Figure 5 summarizes the 

requirements for petroleum piping. Pressurized piping must have a 

release detection device that monitors the line at least hourly and 

automatically shuts off or restricts product flow or sounds an alarm 

when there is an indication of a leak. The owner and operator must also 

conduct either monthly monitoring or an annual line tightness test. The 

monthly monitoring may include vapor monitoring, ground-water 

monitoring, interstitial monitoring, or other methods that meet the 

performance standard or are approved by the implementing agency. The 

performance standards for the piping release detection methods are 

contained in a separate section of the rule (§ 280.44) and are discussed 

in section IV.D.2.e. below.

[INSERT FIGURE 5 HERE.]

The Agency notes that one release detection method can be 

used as the sole method if it can meet both the hourly release detection 

requirement and the annual or monthly release detection requirements. 

For example, double-walled piping with continuous interstitial 

monitoring that meets the performance standard continues to be an 

acceptable option for pressurized piping and would not require shutoffs, 

restrictors, or tightness tests. The system must be equipped, however, 

with an alarm that will indicate when a release into the interstitial 

space has begun.

Suction piping systems meeting the "no leak" criteria 

described below in subsection (c) continue to be exempt from release 
detection. Other suction systems must operate with monthly release 

detection or a line tightness test every 3 years.

(b) Requirements for Pressurized Piping (§ 280.41(b)(1)).

As discussed in the proposal preamble (52 FR 12743-12745), the Agency 

was concerned that pressurized piping, which uses a pump in the tank to 

force product through the line to the dispenser, could result in large 

volumes of product being quickly released to the environment through a 

hole or crack. In contrast, suction piping appears to be intrinsically 

much safer because product is transferred at less than atmospheric 

pressure by a pump near the dispenser drawing product from the tank by 

suction, and failures will result in air or ground water flowing into 

the pipe rather than product being released during operation. The 

Agency considered not allowing pressurized piping at new installations 

but its widespread use, the availability of release detection technology 

(see discussion below), and some of the operational limitations of 

suction piping persuaded EPA to include it in the proposed rule.

Commenters agreed with EPA's position that pressurized 

piping could result in large-volume releases in the absence of release 

detection but felt that pressurized piping with release detection should 

be allowed in the final rule. They noted that pressurized piping is 

widely used, economical, efficient, dependable, and not susceptible to 

vapor lock. Commenters also noted that suction piping is more expensive 

to operate and requires longer times to dispense product and that its 

use is restricted by elevation above sea level, height differences 

between storage and delivery, flow rate, temperature, and length of 

horizontal piping. The Agency has continued to allow the use of both 

suction and pressurized piping in the final rule subject to the 

requirements discussed below.

o Immediate Detection of Large Leaks (§ 280.41(b)(1)(i))

At proposal, data received from state agencies indicated 

that piping was involved in 20 to 35 percent of all releases. 

Pressurized piping was also identified as the most common petroleum 

dispensing system at new installations. Documented cases raised the 

possibility of sudden large releases from these systems. These factors 

led the Agency to conclude that additional release detection was 

required for pressurized piping so that large-volume releases could be 

stopped as quickly as possible. The monthly monitoring frequency 

required for the tank was considered inadequate given the potential 

environmental damage due to a release from pressurized piping. At 

proposal, piping pressure sensing methods were commercially available 

that manufacturers claimed could detect and shut off a release of at 

least 2 gal/hr from pressurized piping. Although the performance of 

these devices had not been evaluated, the magnitude of the problem and 

the availability of control technology caused the Agency to require 

shutoff devices in the proposed rule. The proposal preamble requested 

information on the field performance of pressurized piping release 

detectors (52 FR 12744).
A variety of approaches are available to rapidly detect 

large leaks in pressurized lines. Two main types of continuous in-line 

release detection devices are commercially available for pressurized 

piping: flow restrictors and flow shutoff devices. Both devices react 

to pressure behavior in the line. A flow restrictor monitors the 

increase in line pressure after the dispenser is turned on. If there is 

a leak in the line preventing the line from reaching operating pressure, 

the restrictor allows a limited flow of product through the line to the 

dispenser, and thereby signals a leak to the operator. An automatic 

shutoff device monitors pressure changes during periods when the 

dispenser is off. If the line pressure drops enough to indicate a leak, 

the pump turbine is shut off, and no product can be dispensed. In 

addition to in-line detectors, continuous interstitial, vapor or groundwater monitors may also give rapid reliable warning when a leak occurs.

Commenters generally agreed with the need for pressurized 

piping release detection that was conducted more frequently than 

monthly. Many felt that only flow restrictors should be required 

because they are widely available and have proven performance. Based on 

information from UST installers and on causes-of-release data, flow 

restrictors operating at a 3 gallon per hour detection limit will 

eliminate 80 to 95 percent of the volume of releases occurring from 

piping. These devices have been in use for years and can be immediately 

installed at a large number of existing or new UST installations.

The Agency recognizes that other methods of frequent piping 

detection can achieve the same level of performance as flow restrictors, 

however. The proposed rule allowed interstitial monitoring or 

continuous ground-water or vapor monitoring instead of automatic shutoff 

devices but did not include a performance standard for these methods. 

Research conducted since the proposal (Notice of Availability; 53 FR 

10403) shows that under certain circumstances ground-water monitoring 

will not allow immediate detection of a release. To ensure an 

equivalent minimum level of protection against catastrophic pressurized 

piping releases, the final rule includes the requirement that all 

pressurized piping have automatic line leak detectors that provide 

warning of 3 gallon per hour releases within an hour. EPA expects that 

this requirement can be met using flow restrictors, automatic shutoff 

devices, continuous interstitial monitors, and some continuous vapor 

monitors. Continuous ground-water monitoring may also meet this 

requirement under certain site conditions (e.g., shallow water table). 

EPA expects that some of these devices will be sufficiently sensitive to 

meet the additional monitoring requirements discussed below. If a 

device meets both standards, no additional monitoring is required. A 

detailed discussion of the performance of these systems is contained in 

section IV.D.2.c. of today's preamble.
o Additional Monitoring for Smaller Leaks 

(§ 280.41(b)(1)(ii))

Commenters suggested the use of inventory control or line 

tightness testing in conjunction with flow restrictors, shutoff devices, 

or continuous monitors. The new causes-of-release information acquired 

since proposal shows even more strongly that piping is a major source of 

leaks from UST systems. Because of the importance of controlling 

pressurized piping releases, EPA agrees that additional release 

detection beyond the immediate detection discussed above is necessary. 

Flow restrictors may not detect small releases, so additional monitoring 

is necessary to detect these releases. Therefore, the final rule has 

been revised to require an annual line tightness test or monthly 

monitoring using one of the accepted methods for tank monitoring. Line 

tightness testing is more sensitive than the other methods (see section 

IV.D.2.e. below) and so can be conducted less frequently for equivalent 

protection. Further, because of the problems cited by commenters with 

the reliability of flow restrictors and the ability of operators to 

override them, the final rule also requires that the operation of the 

line leak detector be checked annually in accordance with manufacturer's 

requirements. This system of checks will limit the likelihood that 

pressurized piping will release large volumes suddenly. This approach, 

coupled with requirements for corrosion protection and careful 

installation and testing of piping (which will significantly lower the 

incidence of piping releases over time), will protect human health and 

the environment.

o Secondary Containment for Piping

Some commenters recommended that secondary containment with 

interstitial monitoring be required for all pressurized lines. The 

Agency feels, however, that the release detection options described 

above for single-walled pipes are protective of human health and the 

environment and that the additional stringency gained by double-walled 

pipes does not need to be required. EPA also notes that secondarily 

contained piping is a relatively new technology that would require 

significant new training of installers to "de-bug" the applications of 

this technology for widespread use. In any event, the monthly or annual 

tests will detect the small slow leaks from piping while the shutoffs or 

restrictors will detect the large releases. EPA agrees that secondary 

containment for piping is environmentally protective, and owners and 

operators may choose to install continuous interstitial monitors which 

meet the above standards.

(c) Requirements for Suction Piping (§ 280.41(b)(2)). In 

the proposed rule, all release detection requirements were waived for 

suction piping that meets six design and operating standards concerning 

pressure, slope, run of the piping system, and use of properly located 

check valves. This piping design, common in Europe, ensures that 

little, if any, product will be released if a break in the line occurs. 

The Agency also felt that this exemption would encourage the use of 

suction piping over pressurized piping wherever possible, which is 

desirable because suction systems are less likely to leak than 
pressurized systems. Suction systems which do not meet the criteria for 

exemption were required to be monitored in the same manner as the tank, 

because the Agency believed small, continuing releases were possible 

from these systems. Changes in the requirements for both exempt and 

non-exempt systems are discussed below.

o Design Criteria Revised

The proposed rule contained design criteria for exempt 

suction systems concerning the number and placement of check valves and 

the slope of the piping because small releases can occur in an 

improperly designed or installed system. Two of these criteria have 

been deleted and one criterion has been added in the final rule. First, 

commenters noted that the 2-percent slope mandated in the proposed rule 

is difficult to meet using current design practices, and the API and PEI 

codes of practice recommend a 2-percent slope. Commenters also noted 

that a 2-percent slope decreases the maximum distance between the tank 

and the pump, thus limiting station design. In the final rule, 

therefore, the specific value for the slope has been eliminated, and 

only the general requirement has been retained that the slope be such 

that product will drain back into the tank when suction is released.

Second, the proposed rule also required that suction 

systems have only one check valve as close to the pump as possible and 

not have a foot valve. These criteria overlap, however, and the foot 

valve restriction has been deleted from the final rule. This change 

does not weaken the final rule because the requirement for only one 

check valve near the pump will prevent a large volume of product being 

held in the portion of the pipe from which a leak could occur.

Finally, today's rule contains an additional provision that 

exempt suction systems must have a means of verifying compliance with 

the design requirements. In the preamble to the proposal, the Agency 

noted that suction systems in West Germany are equipped with a means of 

ensuring that the contents of the line are under less than atmospheric 

pressure (52 FR 12745). This serves to ensure that if a hole in the 

line develops the liquid drains back into the tank and is not released 

to the environment. Although the Agency received no comments directly 

related to this issue, commenters did note that service contractors 

frequently correct operational problems with suction systems by adding 

additional check valves to the line. An inspector could not easily 

discover this alteration and the system could begin to leak. 

Consequently, the Agency decided to require that exempt suction systems 

be equipped with a means for an inspector to readily determine that the 

system continues to meet the design requirements.
o Non-Exempt Suction Systems

Under the proposed rule, American-design suction systems, 

which commonly have a check valve near the tank or at piping unions, 

were required to have release detection conducted as frequently as for 

the tank. Commenters on the proposal noted that eliminating check 

valves at piping unions or near the tank is not practical in some 

applications and requested that these systems also be exempt from 

release detection requirements. The causes of release information 

acquired by EPA clearly indicates that both types of suction piping are 

dramatically less likely to have large leaks than pressurized systems. 

Based on this information, EPA requested comment on the use of less 

frequent testing (every 1 or 3 years) for suction systems in the 

supplement to the proposed rules (52 FR 48642). Commenters disagreed on 

an acceptable testing frequency but generally agreed that all forms of 

suction line pose a limited environmental threat. EPA agrees with 

commenters who noted that non-exempt suction systems can have small 

continuing releases under some conditions and, therefore, should not be 

exempt from detection requirements. Because the leaks from these 

systems are limited and will usually be signaled by operating problems, 

EPA believes that a 3-year frequency, in conjunction with required 

prevention measures, is protective of human health and the environment. 

The reduced frequency of testing for these systems should further 

encourage the use of suction systems should further encourage the use of 

suction systems over pressurized systems, even for applications where 

the exempt design requirements are impractical. These incentives add to 

the environmental protection provided by the piping release detection 

standards.

c. Requirements for Hazardous Substance UST Systems (§ 280.42)

The proposed rule required the use of secondary barriers 

with interstitial monitoring at all new or upgraded UST systems storing 

hazardous substances, unless the owner and operator: (1) demonstrated 

that an alternative method of release detection would accurately and 

reliably detect a release of the hazardous substance from the UST system 

and (2) obtained approval to use another method from the implementing 

agency. Also, in the proposal, owners and operators of existing 

hazardous substance USTs were allowed during the 10-year upgrade period 

to use any of the methods of detection allowed for petroleum USTs, if 

the performance requirements for that method could be met. At the end 

of the proposed 10-year upgrade period, owners and operators would have 

to upgrade or replace this release detection with secondary containment 

and interstitial monitoring unless a variance was approved.

After consideration of numerous public comments submitted 

on these issues and additional research, EPA continues to believe that 

release detection and corrective action technologies are not as readily 

understood or widely used for the broad range of hazardous substances as 

they are for petroleum. EPA believes that secondary containment 

continues to be the most effective demonstrated method of release 

detection for new UST systems containing hazardous substances. Thus, 

EPA has retained the proposed approach in the final rule but has revised 
(1) the performance standards for the secondary containment and (2) the 

procedures for receiving a variance. In the final rule, in appling for 

variance, owners and operators of new or upgraded UST systems must 

provide (in addition to the demonstration of the effectiveness of a 

release detection method) information about applicable corrective action 

technologies, the inherent health risks, the chemical and physical 

properties of the stored substance, and any relevant characteristics of 

the particular UST site that would impact a future clean-up. These 

factors will be used by the implementing agency to guide its decision on 

whether to allow the alternate release detection method for the 

hazardous substance.

(1) Release Detection Requirements (§ 280.42(a) and (b)).

Commenters took a variety of positions regarding the 

necessity of secondary containment for hazardous substance USTs. Many 

felt that the approach in the proposal was appropriate while others 

thought that specific chemicals, or all regulated substances, should be 

treated in a manner similar to petroleum. Many of these arguments 

centered on the similarities or differences between certain hazardous 

substances and components of petroleum. Commenters also disagreed about 

the most effective form of secondary containment, some favoring doublewalled tanks, and others advocating excavation liners. Commenters 

generally were opposed to allowing soils as an excavation liner due to 

the difficulty of ensuring that the soils were properly treated and 

compacted.

The final rule has retained the proposed secondary 

containment requirement for new and upgraded hazardous substance UST 

systems with some significant revisions. The final secondary 

containment requirement is based on both technical and implementation 

considerations. From the technical perspective, secondary containment 

is believed desirable because it ensures that all hazardous substance 

USTs will be provided with effective detection methods, and, if a leak 

occurs from the primary containment structure into the interstitial 

space, corrective action will be simplified because it is very unlikely 

to impact the surrounding environment. As discussed in later sections 

of today's preamble, EPA has extensive information on the performance of 

various release detection methods and corrective action technologies 

already being applied to petroleum tanks. (The Agency allowed singlewalled tanks and release detection for storage of petroleum substances 

because of the detectability of these substances and the belief that 

small releases could be cleaned up relatively easily.) Information 

about the performance of release detection and corrective action methods 

for hazardous substances, however, is not as readily available. Most 

importantly, there is very limited field experience with detection 

methods for hazardous substance tanks. This is made more significant by 

the fact that numerous hazardous substances are more toxic than 

petroleum and are less likely than petroleum to be detected by smell or 

taste. It is also important to note that, when replacing these 

hazardous substance tanks, industry has generally chosen to put them 

aboveground, in vaults, or in double-walled tanks. This lack of 

information and experience with effective single-walled tank strategies 
for hazardous substance USTs has caused the Agency to conclude that 

secondary containment is the most technically prudent approach to 

protecting human health and the environment.

In today's final rule, the Agency has given important 

consideration to both technical and implementation concerns. From an 

implementation standpoint, the secondary containment requirement is 

considered feasible by EPA because there are significantly fewer 

hazardous substance systems subject to regulation than there are 

petroleum tanks. In addition, secondary containment apprears to be 

consistent with existing industry practices and state regulations for 

storage of these substances. As noted in the preamble to the proposal, 

state and local programs have adopted a variety of requirements for 

hazardous substance USTs that tend to emphasize secondary containment. 

In addition, these regulatory programs are generally not as widespread 

or well established as petroleum tank programs, which makes adoption of 

the secondary containment standard less disruptive to ongoing 

implementation. Although EPA recognizes that some hazardous substances 

can be both detected and cleaned up as easily as petroleum, there are 

many chemicals that cannot, and specific criteria for distinguishing 

them for UST release detection purposes are difficult to establish, 

especially in a rule to be applied nationwide. Commenters did not 

provide any workable approaches on new information upon which EPA could 

develop such criteria. Owners and operators are eligible for a variance 

if they can demonstrate that effective detection and cleanup 

technologies exist for the specific hazardous substances being stored 

(see the next section of the preamble).

The specific requirements for secondary containment of 

hazardous substance UST systems have been revised based on public 

comment and new information. Many commenters assumed that the 

proposal's alternative for secondary containment with interstitial 

monitoring required full secondary containment that would prevent the 

release of chemicals to the environment even in the event of a 

catastrophic tank failure. The proposal, however, was intended only to 

ensure detection of releases and not necessarily to contain them. For 

example, it allowed both excavation zone liners and double-walled tanks 

that did not have 360 coverage of the inner wall. Based on commenters' 

concerns and the preceding discussion, the final rule requires for new 

or upgraded UST systems storing hazardous substances that the outer 

barrier be capable of containing a release until it is detected and 

cleaned up. The effect of this requirement is to require both doublewalled tanks and liners to completely surround the inner tank and be 

checked for releases as frequently as necessary to prevent the release 

of hazardous substances to the environment should a leak occur. This 

monitoring would, at a minimum, need to be conducted at least monthly.

In the final rule, the Agency has taken an approach that is 

based on the one followed for hazardous waste tanks under Subtitle C of 

RCRA (40 CFR 264, 265; Subpart J). It is the Agency's belief that many 

of the hazardous substances covered in today's rule have properties that 

are very similar to those of hazardous waste. Consequently, both rules 

require that a leak at any time during the operational life of the 
facility will be contained until it is detected and removed from the 

containment system. Because there are significantly more hazardous 

substance UST systems than hazardous waste tank systems, and because 

Subtitle I UST systems are not part of a permitting program, the Agency 

has retained the performance-oriented approach that was proposed. (It 

is the same general approach used for petroleum tanks.) This 

performance-oriented monitoring approach is intended to provide enough 

flexibility to control the greater number and variety of hazardous 

substance tanks, without the use of permits, while at the same time 

providing the same level of protection as provided by the tank 

requirements under Subtitle C of RCRA.

(2) Variance to Release Detection (§ 280.42(b)).

As stated in the proposal preamble, EPA recognizes that 

secondary barriers with interstitial monitoring may not be necessary for 

all hazardous substance UST systems because there may be alternate 

release detection methods that, based on the tank system 

characteristics, location, and the nature of the substance stored 

(52 FR 12741), adequately protect human health and the environment. The 

Agency, therefore, proposed to allow the use of other release detection 

methods if the owner or operator demonstrated that an alternate method 

reliably detects the release of the hazardous substance from the UST 

system and obtains the approval of the implementing agency (see proposed 

§ 280.41(b)).

A number of commenters supported the variance provision, 

while others opposed allowing a variance in any situation. The Agency 

has concluded that the risks posed by the use of an alternate method 

will be minimized by requiring the owner and operator to apply for a 

variance, and by stipulating that an alternate release detection method 

can be substituted only if it is as reliable as those used for petroleum 

and petroleum-based substances, and all performance criteria for the 

release detection method are satisfied at the site. In addition, 

information about available corrective action technologies, and the 

inherent health risks and chemical properties of the substance stored, 

will also need to be provided by the owner and operator to the 

implementing agency for review. These other factors may override the 

detectability criteria. For example, if a given vapor monitoring device 

detects a hazardous substance with better sensitivity, accuracy, and 

response time than it detects petroleum, and if all the other criteria 

for the operation of the method are met at the site, then the owner and 

operator is eligible to apply for a variance from the secondary barrier 

requirement. However, the implementing agency will approve the 

alternate method only after considering the additional information about 

the characteristics of the substance stored and the availability of 

corrective action methods for that substance if a release occurs at the 

site. Thus, although an effective and accurate vapor monitoring method 

is available, the implementing agency may decide not to approve the 

variance request if the UST is located near a drinking water well or 

there is no corrective action technology that can be applied to remove 

the release before this resource is adversely impacted.
For existing hazardous substance USTs, the Agency allows 

the use of alternate release detection for up to 10 years, at which time 

owners and operators must have applied for and received a variance and 

must have upgraded the existing system to new tank standards. Although 

the application for a variance can be made any time within the 10-year 

upgrade period for existing USTs, the owner and operator must meet the 

appropriate performance standards in §§ 280.43 and 280.44 for an 

alternate release detection methods at all times during the 10-year 

interim period.

(a) Application Process. In the preamble to the proposal, 

the Agency requested comments on procedures that could be used by owners 

and operators to apply for a variance (52 FR 12743). Commenters 

provided a number of suggestions on how the variance application process 

could be implemented. These suggestions included a variance application 

procedure similar to the one promulgated in the final rules for 

hazardous waste tanks (40 CFR Parts 264 and 265), a "nationwide" 

variance application procedure for single companies storing similar 

products in tank systems located in several states, or a joint

petitioning procedure for different companies in the same state that 

have similar characteristics of tanks, substances, and release detection 

methods.

The Agency evaluated all the suggested application 

procedures and decided to defer the specific implementation details to 

the implementing agencies. Numerous factors, such as differences among 

the traditional procedures already followed by implementing agencies, 

variability of site conditions, and the number and configuration of 

tanks at each site, suggest that administrative details for dealing with 

this variation should be left to the specific agency reviewing the 

request. The Agency plans to develop information about a number of 

variance application options that can be used by the implementing 

agencies in designing a variance process in their jurisdiction. The 

final rule contains only the baseline requirements that the owner and 

operator must satisfy in order to use a substitute method of detection 

at new or upgraded hazardous substances USTs; these requirements are to: 

(1) demonstrate the detectability of the substance using the 

alternative release detection method; (2) provide data about the 

corrective action technology that will clean up a release within the 

constraints of the UST site characteristics and the inherent chemical, 

physical and health-risk properties of the substance; and (3) obtain 

variance approval before the installation and operation of the alternate 

release detection method.

(b) Evaluation Criteria. In response to EPA's requests 

for public comment on the type of information and criteria that could be 

used by the implementing agencies to grant variances (52 FR 12742), commenters recommended that EPA develop a list of hazardous substances that 

would qualify for variances on a class basis. They also recommended 

that EPA develop a list of hazardous substances that are petroleum-like 

substances as well as identify physical properties for hazardous 

substances that could be considered for variances. No commenters 

provided a workable set of criteria for doing this, however. 

Significant new information was not provided by commenters concerning 
the characteristics of hazardous substances. The Agency proposed to 

compile a similar list of the specific petroleum substances but rejected 

this approach in the final rule. (See section IV.A.4. for a discussion 

of the definition of "petroleum" and "petroleum UST systems.") After 

considering the different evaluation criteria in a variance program, the 

Agency decided that a specific set of national evaluation criteria is 

not workable given the diversity of the of the chemical properties of 

the hazardous substances, the USTs in which they are stored, and the 

variability of site characteristics. The Agency believes that specific 

variance program implementation details (for example, the use of "class" 

variances) are best left to the implementing agencies. The Agency does, 

however, intend to assist the implementing agencies in their variance 

program development by providing alternative procedures for simplifying 

the application and approval process and by providing more information 

about the general criteria that must be satisifed at a minimum 

nationally in each variance application.

(c) Specific Changes to the Rule. The final variance 

requirements only differ in minor ways from those in the proposed rule. 

The requirement to notify the implementing agency of the intent to 

conduct a demonstration for a variance has been removed. Instead, 

owners and operators will be required "to demonstrate that an alternate 

method can detect a release" before it is used at a new or upgraded UST 

system. Thus, prior notification is simply an item of administrative 

convenience that can be required by implementing agencies at their 

discretion. The final requirements make clear that it is advantageous 

for the owner and operator to apply as early as possible, because an 

alternative method cannot be used to meet the new or upgraded hazardous 

substance UST system release detection requirements without approval of 

a variance by the implementing agency.

In the final rule, owners and operators are also required 

to submit to the implementing agency information about the availability 

of corrective action technologies that could be used should there be a 

release of the stored hazardous substance at that site, including a 

consideration of any unusual health risks that are posed by a release of 

the stored substance. The Agency believes that this additional type of 

information is needed by the implementing agency to be able to evaluate 

variance applications. This change is in response to those commenters 

who believed that the proposed approach was not stringent enough and 

could result in adverse impacts to human health and the environment. 

Also, these new criteria provide the further clarification of evaluation 

criteria that was suggested as needed by other commenters. EPA believes 

these general criteria will more adequately (than the proposed approach) 

ensure that only variances will be applied for that, if approved, will 

protect human health and the environment.
d. Methods of Release Detection for Tanks (§ 280.43)

The proposed rule presented in one section the release 

detection options that addressed the complete UST system (both tanks and 

piping). It also specified in one section the methods that need to be 

combined, the frequency of testing, and the applicable performance 

standards. The final rule has been reorganized in response to several 

commenters who stated that this format was unclear and that it was 

confusing in the way it combined tank and piping detection methods and 

petroleum and hazardous substance requirements. All of the general 

requirements, such as combinations and testing frequencies, are now 

contained in § 280.41 for petroleum and § 280.42 for hazardous 

substances. Any substantive changes in these areas are discussed in 

previous sections of the preamble (IV.D.2.b. and c.). The final rule in 

§ 280.43 now simply lists the methods that can be used for detecting 

leaks in tanks and the conditions under which they can be used to meet 

the requirements of § 280.41 and § 280.42. The methods applicable to 

underground piping are listed seperately in § 280.44 and are discussed 

in a later section of this preamble (IV.D.2.e.)

!ivd2d1!

1) Inventory Control (§ 280.43(a)). The proposed rule allowed the 

use of monthly inventory control in combination with periodic tank 

tightness testing as a method of release detection. Although listed as 

a separate method in the final rule, inventory controls still must be 

combined with another method of detection (see section IV.D.2.b.1. 

above). The Agency acknowledged that inventory control is affected by 

many variables but maintained that the technique is effective when 

correctly performed by trained personnel. The proposed rule contained 

weekly and monthly performance standards and procedural requirements to 

optimize the effectiveness of inventory control.

Commenters generally felt that the performance standards 

and the procedures were too stringent, and that the method was 

unreliable because the variables were essentially uncontrollable. EPA's 

research since proposal demonstrates that the proposed rule would in 

fact result in an unacceptable rate of false alarms; consequently, the 

final rule has been revised to eliminate the proposed weekly performance 

standard and to change the monthly performance standard to 1 percent of 

monthly product throughput plus 130 gallons. In addition, the proposed 

requirement that only tanks partially within the ground water perform a 

monthly test for water within the tank has been expanded to apply to all 

tanks. Also, the proposed limitation on the accuracy of the dispensing 

meter has been revised to make it consistent with local weights and 

measures standards. These changes are discussed in more detail below.

(a) Performance Standard. EPA proposed that inventory 

control be conducted to detect a release of at least 5 percent of flowthrough on a weekly basis and 0.5 percent of flow-through on a monthly 

basis; the latter standard was based on an API recommended practice. 

The Agency was concerned that having only a monthly inventory control 

requirement would lead to large releases occurring for a month before 

detection. Therefore, the proposal included a weekly loss standard that 

was intended to provide early warning of major losses.
Several commenters stated that the proposed 5 percent 

weekly and 0.5 percent monthly flow-through requirements were too 

stringent and too difficult to achieve, particularly the weekly 

requirement. They also felt that the weekly requirement would result in 

many false alarms, thus unnecessarily burdening owners and operators and 

the implementing agencies. They suggested that detection of such small 

leaks from tanks with low flow-through of product was difficult, that 

the temperature influences on volume were too great to obtain accurate 

data, and that the technology was not sufficiently developed to detect 

small releases and, at the same time, ensure against false alarms. 

Other commenters supported the monthly flow-through requirement.

In response to commenters' concerns, the Agency has since 

proposal evaluated several approaches to inventory control to determine 

the minimum leak rate that could be reliably detected. The evaluation

considered basing inventory leak determinations on the percent of 

throughput, percent of throughput plus a constant volume, or number of 

days exceeding a given loss. A data base of actual inventory records 

consisting of over 20,000 measurements at nearly 600 tanks nationwide 

was used in a computer simulation of leak rates. The study indicated 

that the proposed monthly standard would result in a large number of 

false alarms (approximately 30 percent on a monthly basis). The most 

sensitive of these inventory control methods would detect a loss of 

about 1 gallon per hour at a PD of 95 percent and a PFA of 5 percent. 

This investigation revealed that using sophisticated statistical 

inventory control or pooling the inventory data for several months would 

improve the sensitivity of all the methods. Notice of this study was 

published for comment in the FEDERAL REGISTER (53 FR 10403). A 

commenter submitted a study that confirmed the high false alarm rate of 

the monthly standard and indicated that the weekly requirement also had 

an unacceptably high false alarm rate (over 50 percent).

In response to these comments and the studies discussed 

above, EPA has modified the final rule. The Agency acknowledges that 

other methods can detect smaller releases, but the final rule allows 

inventory control combined with tank testing for use during the phase-in 

period or with new, protected tanks because of its general 

effectiveness, low implementation costs, and ease of application. As 

discussed above, however, the proposed 5 percent weekly detection rate 

produces an unacceptably high false alarm rate, as does the proposed 0.5 

percent monthly standard. Consequently, the requirement for weekly 

inventory control has been omitted from the final rule and the monthly 

requirement has been changed to 1.0 percent of flow-through plus 130 

gallons, which has a false alarm rate of about 5 percent. The Agency 

believes that owners and operators will take inventory results more 

seriously when the number of false alarms are reduced. EPA has further 

concluded that inventory control offers a practical and effective means 

of detecting releases only when combined with tank testing or automatic 

tank gauging.

In addition to the performance standard, the proposed rule 

contained six restrictions that had to be followed when conducting 

inventory control. The restrictions that received the most comment 
involved measurement accuracy (to 1/8 inch), the accuracy of the 

dispensing meters, and the requirement to measure water only when some 

portion of the tank is below ground water. These restrictions are 

discussed below.

(b) Dipstick Measurement Accuracy. At proposal, the 

Agency believed that reading dipsticks to the nearest 1/8 inch could be 

performed and that reading to this level would reduce major errors 

involved with the measurement of the stored product's height (52 FR 

12727). A number of commenters felt that many factors interfere with 

precise dipstick measurements, and, therefore, it is not reasonable to 

require accurate measurements for an imprecise method. Commenters also 

felt that the 1/8-inch requirement was inconsistent with existing 

conversion tables, which are usually marked in whole inches. Other 

commenters suggested reasons why dipstick methods of measurement were 

inappropriate. The EPA-sponsored research discussed in the previous 

section indicates that increased stick-reading accuracy down to and 

including 1/8-inch does improve the performance of inventory control. 

The Agency also has concluded that existing dipsticks marked to 1 inch 

can be successfully read to the nearest 1/8 inch to improve accuracy, or 

that conversion tables can be modified.

(c) Dispensing Meter Accuracy. Accurate metering is 

essential to inventory control. Therefore, based on the National 

Conference on Weights and Measures Standard, the Agency proposed that 

dispensing should be metered to within 5 cubic inches for every 5 

gallons of product withdrawn, even if it meant that certain owners and 

operators would have to install or calibrate dispensing meters. Several 

commenters preferred the requirement to be 6 cubic inches per 5 gallons, 

in accordance with the National Bureau of Standards (NBS) Handbook #44, 

or that it be the same as the local weights and measures standards. EPA 

agrees with commenters that local weights and measures calibration 

standards will be adequate to ensure accurate inventory reconciliation 

where these standards are applicable. At dispensing meters that are not 

covered by local weights and measures standards, the nationally 

recognized NBS standard is appropriate. The final rule has been revised 

accordingly to allow both calibration standards.

(d) Monthly Water Check. The proposal required the 

measurement of any water in the tank at least monthly if any portion of 

the tank is within the water table. Water in a tank could result from 

ground-water intrusion, indicating that there is a hole in the tank. 

One commenter suggested more frequent measurement of water under all 

situations rather than only in those cases where the tank is partially 

within the water table. The Agency agrees that water could enter the 

tank even when the water table is deep (e.g., when rain water 

temporarily collects in the excavation pit). The presence of water in a 

tank can indicate a hole in the tank, whether the water comes from 

ground water or rain water. The provision now requires the water 

measurement monthly at all tanks conducting inventory control. The 

monthly frequency was retained because it agrees with the frequency of 

other release detection methods, which was selected as the frequency 

that is protective of human health and the environment. The measurement 

of water in the tank is a simple procedure routinely conducted by many 
operators already, so this requirement should not significantly increase 

the operator's burden.

(2) Manual Tank Gauging (§ 280.43(b)). 

In the supplement to the proposed rule (52 FR 48635), EPA 

requested comments on the use of static inventory control (or manual 

tank gauging) as a release detection technique for used oil (or other 

types of) UST systems. Commenters generally supported the use of this 

detection method, although they differed widely on what tanks should be 

allowed to use this method, how long the test should be, and how 

frequently it should be performed. Research submitted by one commenter, 

and EPA's own analysis, indicates that this method is as effective as 

inventory control at smaller tanks (below 2,000 gallons) and can 

reliably detect leaks of 0.2 gallon per hour for tanks of 550 gallons or 

smaller. Consequently, final rule allows its use as the sole release 

detection method for tanks 550 gallons or less in capacity. Also, 

manual tank gauging can be used in the final rule for tanks of 551 to 

2,000 gallons as a substitute for the inventory control part of the 

method (that combines monthly inventory control with periodic tank 

tightness testing). Manual tank gauging cannot be used to meet the 

release detection requirements at tanks larger than 2,000 gallons.

Commenters were divided over the applicability and 

effectiveness of manual tank gauging. Some commenters recommended that 

manual tank gauging be approved because it is effective and inexpensive 

and because used oil poses less environmental risk than other regulated 

substances. They also noted that the lack of piping and small 

deliveries at these tanks made releases less likely. Some commenters 

opposed the use of manual tank gauging because they believed the method 

is not sensitive enough and includes too much room for human error. 

These commenters also frequently recommended requiring secondary 

containment for used oil because it contains hazardous constituents and 

no other detection methods are as effective.

As discussed earlier in today's preamble (section 

IV.A.3.g.), the Agency believes that used oil does not differ 

substantially from petroleum products and should be regulated in the 

same manner. Consequently, today's final rule requires that these tanks 

conduct accurate monthly monitoring using the methods applicable to 

other petroleum tanks. The Agency requested comments in the supplement 

to the proposed rule on the possibility of including manual tank gauging 

as a monitoring alternative; specifically, for used oil tanks or other 

types of tanks. Commenters recommended a wide range of specific 

requirements. Suggested frequencies ranged from daily to every 5 years 

and suggested test lengths ranged from 6 hours to 72 hours or longer. 

Some commenters recommended this test should apply to other regulated 

substances, especially products similar to used oil. Commenters 

disagreed on the appropriate size limit for tanks allowed to use this 

method.

In order to determine more precisely the performance of 

this method, EPA analyzed a report submitted by a commenter. EPA's 
evaluation (Notice of Availability; 53 FR 10403) indicates that for 

tanks smaller than 550 gallons, manual tank gauging can detect 0.2 

gallon per hour leaks with a PD of 0.95 and a PFA of 0.05 when performed 

in accordance with today's rule. For tanks between 550 gallons and 

2,000 gallons the method achieves the performance of inventory control. 

For those tanks, the method is capable of detecting leaks of 1 gallon 

per hour or less with a PD of 95 percent and a PFA of 5 percent, even 

under extreme temperature conditions. Based on commenters' suggestions 

and these study results, the final rule includes manual tank gauging as 

an allowed leak detection method. In today's rule, only tanks of 550 

gallons or smaller may use this as the sole method of release detection. 

Larger tanks (551-2,000 gallons) may use it in place of the inventory 

control part of the release detection method that combines inventory 

control with periodic tank tightness testing.

According to the Agency's evaluation, the performance 

described above can be achieved if the following limitations are met: 

the test period is at least 36 hours, depth measurements are taken twice 

and averaged, and the depth is read to the nearest one-eighth of an 

inch. These criteria have been included in today's final rule.

(3) Tank Tightness Testing (§ 280.43(c)).

The proposed rule allowed periodic tightness testing in 

conjunction with monthly inventory control as a release detection method 

for all tanks. While acknowledging the uncertain performance of tank 

testing, the Agency believed that it was a demonstrated and effective 

method that would be available to meet the large demand for release 

detection following promulgation. To maximize the performance of tank 

tightness tests, the proposed rule included a performance standard of 

0.1 gallon per hour at a PD of 99 percent and a PFA of 1 percent. 

Commenters disagreed about whether tightness testing should be included 

in the rule and what level of performance it should be required to meet. 

Additional evaluation by EPA indicates that, although few methods can 

now meet the proposed standard, several methods could make a few changes 

to equipment and protocol and meet the proposed standards. For these 

reasons, the final rule retains the proposed tank testing standard of 

0.1 gallon per hour.

(a) Performance Standard. At proposal, EPA recognized 

that many factors such as temperature changes, tank end deflection, and 

vapor pockets affect the accuracy of tank tightness tests (52 FR 12724-

12725). To limit the allowable methods to those that most effectively 

compensate for these problems, the Agency included a performance 

standard in the proposed rule. The level of this standard was selected 

based on the results of the national survey of underground motor fuel 

storage tanks and the experience of tightness testing practitioners; 

little evidence was available to support the NFPA 329 criterion of 0.05 

gallon per hour. The proposed standard of 0.1 gallon per hour at a PD 

of 99 percent and a PFA of 1 percent was believed to be the maximum 

performance achievable on the typical sizes of tanks in use. A high PD 

was included to adequately protect human health and the environment, and 

a low PFA was included to prevent a heavy burden on owners and operators 
and the implementing agencies that is caused by investigating a large 

number of false alarms.

In the proposal preamble, EPA acknowledged that there was 

insufficient information on the performance of available tank tightness 

tests, particularly their ability to meet the NFPA 329 standard of 0.05 

gallons per hour with the proposed probabilities of detection and false 

alarm. It was further stated that the Agency was beginning an 

investigation to acquire this data (52 FR 12724-12725). Since that 

time, EPA's research laboratory at Edison, New Jersey, has evaluated 25 

tank tightness testing methods representing a wide range of approaches. 

During each evaluation, blind tests were conducted by company 

operators, the data were evaluated by EPA, and computer models were used 

to simulate leak rates and probabilities and compare them to the 

operational data. The results of these evaluations indicate that, while 

most of these currently available methods of tank tightness testing are 

capable of detecting leaks of 0.1 gallon per hour, only a few could 

presently detect this leak rate at the specified probabilities. Even 

with the oftentimes simple equipment and procedural changes that are 

necessary to achieve the needed level of improved performance, some

methods probably would not be able to meet the proposed PD and PFA. 

Notice of the results of this study was published in the FEDERAL 

REGISTER on March 31, 1988 (53 FR 10403).

Some commenters felt that tightness testing is too 

unreliable to be an allowable release detection method, at least without 

further evaluation. Several commenters stated that the proposed 

standard was too stringent to be met with existing technology, 

particularly for larger tanks. Others recommended a more stringent 

standard for the release rate, usually citing the NFPA 329 criterion of 

0.05 gallon per hour as the way to spur development of the technology. 

One commenter suggested that the performance standard should become more 

stringent over time as the methods develop. The proposed standard was 

supported by some commenters.

Based on the Agency's evaluation of tank tightness test 

methods and the concerns raised by these commenters, the final 

performance standard has been revised. Many of the methods evaluated by 

EPA at its Edison, New Jersey laboratory were able to detect a release 

of 0.1 gallon per hour so this value was retained in the final rule. 

The detection probabilities associated with the standard have been moved 

to the general requirements section (and are discussed earlier in this 

preamble in section IV.D.2.a.). During the two years before these 

probabilities are effective, the Agency believes additional standards 

are needed. Thus, the final rule language has been changed to include 

the requirement that tank test methods must account for the effects of 

thermal expansion or contraction of the product, vapor pockets, tank 

deformation, evaporation or condensation, and the location of the water 

table. These variables have been identified as important in EPA 

research (Notice of Availability; 53 FR 10403) and in the NFPA 329 

recommended practice.

The Agency's evaluation indicates that many tightness test 

methods can meet the final performance standard with relatively minor 
procedural or equipment changes. Such changes, however, have not been 

developed and instituted by the manufacturers of many of the different 

devices, tried in the field, or evaluated in laboratory conditions. In 

addition, manufacturers have not described their performance in terms of 

probability of detection and probability of false alarm in the past. 

There will be a large demand for tightness testing for release detection 

and confirmation following promulgation of the final rule. Tightness 

testing is the most widely available release detection method and the 

method that is likely to be used by many UST owners and operators over 

the next 5 to 10 years. EPA was concerned that, if few or none of the 

tightness test methods could meet the performance standard, there would 

be insufficient industry capacity to meet demand for release detection. 

For these reasons, the final rule has been revised to delay the 

effective date of the probabilities of detection and false alarm (see 

discussion of this delay in section IV.D.2.a.5. above).

The Agency decided to give manufacturers 2 years in which 

to develop and put into operation the necessary procedural and equipment 

changes or to develop new methods that meet the entire performance 

standard. Such a delay was recommended by some commenters and will 

ensure that necessary equipment and procedural changes can be made by 

method manufacturers. As discussed previously in the preamble, the 

Agency believes significant environmental benefit can be obtained by 

conducting release detection quickly. The delay in performance 

standards should allow more wide spread and rapid testing of tanks.

(b) Relationship of the Final Performance Standard to NFPA 

329. As noted above, some commenters felt that the proposed performance 

standard of 0.1 gallon per hour at a PD of 99 percent and a PFA of 1 

percent was too lenient and was a relaxation of the standard currently 

followed by the industry, which is 0.05 gallon per hour recommended in 

NFPA 329. However, the Agency has concluded that the final performance 

standard is not less stringent than NFPA 329. First, the standard in 

the final rule still requires testers to declare a leak at a threshold 

value of 0.05 gallon per hour (see section IV.D.2.a.4. above). Second, 

the NFPA guideline specifies a detectable leak rate but does not specify 

the probability with which this leak rate must be detected. Most 

existing volumetric methods will detect 0.05 gallon per hour leaks at 

least a portion of the time. A relatively poor method that detects a 

leak of 0.1 gallon per hour with a PD of 50 percent and a PFA of 1 

percent could still claim to meet the NFPA criterion because the 

probability of detecting a leak is not specified. Direct comparison to 

the Agency's performance standard shows that the NFPA 329 criterion 

would allow more leaks to go undetected and also cause more false 

alarms. EPA's final performance standard intended to eliminate the use 

of poor tightness test methods, ensure that more leaks are detected, and 

cause fewer false alarms. Thus, it provides for better protection of 

human health and the environment while ensuring unnecessary or 

counterproductive burdens on owners, operators, and implementing 

agencies are minimized.

(c) Large Tanks. In the preamble to the proposed rule, 

EPA stated its doubts that the performance standard was attainable for 

large tanks (52 FR 12725). Some commenters agreed and some disagreed. 
Research at EPA's Edison facility suggests that the 0.1 gallon per hour 

standard cannot be met for large tanks using current test methods. 

Rather than allowing less stringent test methods for large tanks, which 

would create the potential for ignoring large releases, EPA believes 

that owners and operators of large tanks will have to select other 

release detection methods besides tank tightness testing unless improved 

or new methods are developed that allow the standard to be met for the 

larger tanks. (See section IV.A.3. of this preamble on bulk underground 

storage tanks.)

(4) Automatic Tank Gauging Systems (§ 280.43(d)).

Automatic tank gauging systems (ATGS) were included in the 

proposed rule as one of the options for release detection (although the 

name of this option as proposed was "automatic monitoring of product 

level and inventory control"). These monitors generally have two modes 

of operation: leak detection mode (product level monitoring) and 

inventory control mode. The proposed rule required that the leak 

detection mode be used at a minimum once a month and meet a performance 

standard of 0.2 gallon per hour with a PD of 99 percent and a PFA of 1 

percent and that the automatic inventory control be conducted to meet 

the performance requirements for manual inventory control. Some 

commenters stated their belief that ATGS are unreliable, unproven, and 

too costly. Other commenters felt that the proposed performance 

standards were too stringent. Many commenters favored the use of ATGS 

but suggested changes to the requirements in the proposed rule. As 

discussed below, the Agency has retained ATGS in § 280.43(d) of the 

final rule. The proposed leak rate standard has been retained but the 

probabilities have been revised and their effective date delayed 2 

years. The proposed requirement that the tank be 80 percent full at the 

time of the test has been deleted. These changes and comments are 

discussed in more detail below.

(a) Performance Standard. At proposal, the Agency 

recognized there were limited performance data on ATGS, and that there 

was still significant opportunity for human error. However, ATGS were a 

relatively commonly used release detection method with the potential to 

be very sensitive in detecting leaks, and EPA wanted to include as many 

effective release detection options as possible in the rule to provide 

flexibility (52 FR 12736-12737). To limit the allowable ATGS to those 

that effectively control the possible sources of error, the proposed 

rule included a performance standard of 0.2 gallon per hour with a PD of 

99 percent and a PFA of 1 percent. The 0.2 gallon per hour value was 

based on the equipment manufacturers' claims. This performance standard 

was intended to challenge manufacturers to prove that their systems 

could meet the standard.

Some commenters felt that ATGS were unproven and unreliable 

as a release detection method primarily because of their sophisticated 

electronic components. Other commenters felt that the PD was too 

stringent, while others agreed with this part of the proposed 

performance standard. A commenter provided a study conducted over 

several months at an operating service station equipped with several 
ATGS. One of the devices already clearly achieved the proposed 

performance standard. This study confirmed the Agency's conclusion that 

ATGS can be effective in field situations; thus, this release detection 

method has been retained in the final rule.

EPA's own research and the results of the field evaluation 

of ATGS demonstrate that 0.2 gallon per hour leaks can be reliably 

detected by several of the difficult types of available devices, and the 

proposed leak rate of 0.2 gallon per hour has been retained in the final 

rule, but the PD has been changed to 95 percent and the PFA to 5 

percent. In addition, the final rule schedules the PD and the PFA 

standards to take effect 2 years after the effective date of today's 

rules (see discussion of this delay in section IV.D.2.a.5. above). Any 

owner or operator installing an ATGS in the intervening 2 years will not 

have to replace it after 2 years, unless it does not meet the 

performance standard. EPA's review of the systems now available 

indicates that they should be able to meet the standards with only minor 

adjustments.

Some commenters felt that the Agency should set a 

detectable leak rate for ATGS of 0.1 gallon per hour rather than the 0.2 

gallon per hour requirement in the proposed rule. EPA, however, does 

not agree because current equipment as presently used cannot meet such a 

standard, and the suggested approach would effectively eliminate ATGS as 

a release detection method. Furthermore, since the product level test 

is conducted monthly, the performance of this method can statistically 

equal or exceed the sensitivity achieved by periodic tank testing, even 

though the monthly performance standard is less stringent. The Agency 

intends to keep as many effective methods available to the owners and 

operators so that they will have flexibility in selecting a release 

detection method that best suits their needs. 

(b) 80-Percent-Full Requirement. The proposed rule 

required that the tank be 80 percent full during the monthly test. This

requirement was intended to ensure that a large portion of the tank's 

surface was checked for releases (52 FR 12737).

Many commenters opposed this requirement because it would 

be difficult for tanks with low monthly flow-through to implement, and 

it would also be an impediment to businesses with UST systems that are 

in use continuously. New information now indicates that this limit on 

conducting the test is unwarranted. Information from experienced UST 

field personnel, a study in Suffolk County, NY, and comments received by 

EPA demonstrate that most corrosion holes occur in the sides and bottom 

of tanks, not the top, so there is little need to always test the top of 

the tank for releases.

In the absence of a specific requirement, release detection 

tests conducted every 30 days are expected to include tests over the 

range of levels to which the tank is typically filled, so those areas of 

the tank routinely in contact with product will be tested. The 

inventory control requirement will also ensure that releases from the 

top of the tank are detected if they occur. Also, many owners and 

operators do not keep their tanks 80 percent full during normal 
operation; if tanks are rarely filled above a certain point, testing 

above that point is simply unnecessary. Also, the overfill prevention 

requirements in § 280.20 and § 280.30 of today's rule will prevent 

product from reaching the very top of the tank. Therefore, the Agency 

has deleted this requirement from today's final rule.

Although testing at 80 percent of capacity is no longer 

required, the testing procedure should be conducted when the tank is 

near its highest level and the testing should be conducted after waiting 

a sufficient time after the delivery of the product. This waiting 

period is necessary because, after product is added to the tank, it 

takes time for the product to mix and achieve the nearly static 

condition necessary to conduct meaningful product level monitoring (52 

FR 12725). EPA anticipates that this waiting period will become a part 

of the manufacturer's recommended procedures as they attempt to meet 

today's standard concerning detection probabilities.

(c) Combination with Inventory Control. In combination 

with ATGS, the proposed rule required inventory control that meets the 

same performance standards required for manual inventory control. 

Inventory control was required in addition to product level monitoring 

because it was believed that product level monitoring was not as 

accurate as tank tightness testing or external methods and, therefore, a 

backup release detection method was needed. This requirement is not 

burdensome because ATGS routinely collect the information needed to 

conduct inventory control. No comments were received on this issue. 

Therefore, inventory control is still required in conjunction with ATGS 

in the final rule. Some of the performance standards for inventory 

control have been revised in today's final rule and are discussed in 

section IV.D.2.d.1. above.

(d) Effectiveness with Piping. A commenter was concerned 

about the effectiveness of ATGS in detecting releases from piping. EPA 

agrees that, in the leak detect mode, this method will not detect piping 

leaks, and the inventory mode will detect piping leaks but not with 

sufficient sensitivity to detect small leaks. The causes-of-release 

information collected by EPA since the proposal (see section II.F. of 

this preamble) indicates that piping is a major source of releases. 

Therefore, the final rule has added several requirements for piping (see 

section IV.D.2.b.2. of this preamble). The owners and operators of UST 

systems using ATGS as a release detection method for the tank will have 

to select an additional means of release detection for the piping, such 

as line tightness testing.
(5) Vapor Monitoring (§ 280.43(e)).

The proposed rule allowed the use of vapor monitoring in 

the excavation zone as a method of release detection as long as certain 

conditions and limitations were met that maximize performance. The 

information available to the Agency at the time of proposal indicated 

that vapor monitoring was, under optimum conditions, a sensitive and 

reliable release detection method. Research conducted by the Agency 

since the proposal, as well as information submitted by commenters, has 

confirmed that vapor monitoring is capable of detecting extremely small 

leaks (0.003 gallon per hour) under certain conditions. Some of the 

proposed conditions concerning the use of this method, however, now 

appear unnecessary. In summary, the final rule includes vapor 

monitoring, omits the 500-ppm background restriction, and allows 

monitoring for selective components of the stored regulated substance, 

including tracers mixed in the substance.

(a) Effectiveness of Method. Some commenters expressed

concern that vapor monitoring was not developed enough to be relied upon 

as a sole method of release detection. The Agency solicited comments 

and additional data on the effectiveness of vapor monitoring in the 

proposal preamble (52 FR 12728). EPA included it as a method of release 

detection in the proposal because existing data indicated that it should 

be an extremely sensitive monitoring tool and it has already been used 

successfully in some state and local UST programs. The Agency has 

received no research results or data from commenters that would cause it 

to alter its earlier conclusions. In fact, several commenters submitted 

detailed field and experimental data verifying the effectiveness of 

vapor monitoring. A theoretical computer modeling study done by EPA 

confirms these results (Notice of Availability; 53 FR 10403). Although 

there are still not enough data to specify a more complete performance 

standard for this method (in terms of probability of detection, false 

alarm, and leak rate), the Agency believes this method will provide 

effective release detection, and has retained it as an option in the 

final rule, as long as it meets the limitations discussed below.

In response to concerns raised by some commenters, the 

Agency wishes to note that in the final rule, a vapor monitoring well 

does not necessarily mean a typical ground-water well. Instead, a vapor 

monitoring well means any sampling point from which vapors are collected 

and brought to the monitor by any means.

(b) Background Concentration. In the proposed rule, EPA 

limited the use of vapor monitoring to those areas with less than 500-

ppm background concentration of total organic hydrocarbons in the soil 

gas of the excavation zone. Many commenters felt that the 500-ppm 

restriction was too stringent, stating that natural background 

concentrations of methane, for example, are higher than 500-ppm in some 

areas of the country. Other commenters wanted a restriction based on 

site-by-site evaluations. The 500-ppm background level was originally 

set as an attempt to recognize that background effects can interfere 

with effective vapor monitoring (52 FR 12729-12731). Commenters 

described research and field experience, however, that indicate vapor 
monitoring should work well at several thousand ppm levels in the soil 

gas if a volatile substance (such as gasoline) is being stored in the 

tank. In addition, EPA research has shown that at many sites having no 

recorded release from the UST system, the total background concentration 

exceeds the 500-ppm level. This type of background level is probably 

due to an accumulation of spills and overfills.

To avoid precluding the use of vapor monitoring at many 

sites where it is potentially applicable, no specific numerical 

restrictions on background levels is included in today's final rule. 

Instead, there is now a more general performance requirement that the 

background concentration must not interfere with the ability of the 

method used to detect releases. For example, at a site with too high a 

background level (e.g., over 10,000 ppm for gasoline), leaks may not 

produce a detectable concentration increase over background. 

Determining if the background levels are too high depends on the 

resolution of the sensor, the volatility of the product being monitored, 

and other site conditions.

(c) Measurable Component. Several commenters expressed 

concern that the proposal did not allow monitoring for specific 

components of the stored substance and, instead, appeared to be focusing 

only on total organic hydrocarbons as the detection criterion. EPA's 

research indicates that monitoring for specific components or tracer 

compounds may be very advantageous under certain site conditions because 

it eliminates some of the difficulties with background interference 

levels and false alarms. For example, sensors that detect only the 

lightest components of gasoline (e.g., butanes and pentanes) may suffer 

fewer problems with high background levels because these constituents 

vaporize so rapidly that the potentially confounding effects of past 

spills at the site are minimized.

Monitoring for these components might also allow spills to 

be more easily distinguished from equipment leaks, because the level of 

the light chemical components would return to background levels more 

quickly if it was suddenly elevated due to an episodic event like a 

spill. Similarly, if a carefully selected tracer compound that is not 

already present at the site is placed in the tank, background 

interference problems can be eliminated. Some of the advantages of 

tracer methods were also discussed in the proposal preamble (52 FR 

12730).

For the above reasons, EPA believes that effective vapor 

monitoring systems can be designed to monitor for specific components, 

tracer compounds, or total organic hydrocarbons. Consequently, the 

Agency explicitly allows these additional methods in § 280.43(e) of the 

final rule.

(d) Sensitivity of the Vapor Monitor. The proposed rule 

stated that the threshold of the vapor monitor must be preset 

specifically for the type of regulated substance stored in the UST. 

This requirement was included in an attempt to increase the sensitivity 

of the monitor to detect releases in areas with background hydrocarbon 

levels. Since proposal, however, changes have been made to the vapor 
monitoring requirements based on public comment and new EPA analysis 

that make this requirement unnecessary or even undesirable. Tracer 

compounds may now be used for vapor monitoring, so specificity of the 

monitor to the regulated substance is undesirable. The EPA-sponsored 

computer modeling that was conducted on vapor monitoring performance 

indicated that, in some circumstances, a monitor would be more effective 

if it monitored for a single component of the stored substance than the 

complete stored substance because it would be able to differentiate more 

distinctly between a leak of that component and existing background 

hydrocarbon levels. Again, specificity of the monitor to the complete 

regulated substance would be undesirable. The final rule now simply 

requires that the monitor be capable of detecting a significant increase 

above background of the regulated substance, a component or components 

of the substance, or a tracer compound. This change will allow the use 

of existing sensitive monitors such as those measuring BTX (benzene, 

toluene, xylene) or "total hydrocarbons" because they can detect 

components of many regulated substances.

(6) Ground-Water Monitoring (§ 280.43(f)).

The proposed rule allowed the use of monitoring for free 

product on top of the ground-water table to determine the presence of a 

release from an UST system. Many commenters agreed with this approach 

to release detection but wanted EPA to ease some of the limitations 

placed on the use of the method. The final rule still allows monitoring 

on top of the water table for free product but with several changes: 

well placement is no longer limited to the excavation zone; the well 

screen must be designed to prevent clogging and intercept the water 

table at both high and low ground-water conditions; and the well must be 

sealed from the ground to the top of the filter pack.

(a) Effectiveness. In the proposal the Agency recognized 

that there are several concerns about the use of ground-water 

monitoring, primarily the fact that the resource being protected (i.e., 

ground water) is the medium in which the release is detected. The 

Agency included this release detection method in the proposed rule, 

however, because this method has been demonstrated to successfully 

detect small petroleum releases and it is currently in widespread use in 

several state UST programs, such as that in Florida. EPA proposed 

limiting ground-water monitoring only to floating free product because 

its presence can be detected more quickly and reliably following a 

release than can dissolved product. The proposed rule also contained 

several limitations on well design, well placement, and equipment 

performance that together were intended to limit the use of this method 

to those conditions under which rapid detection could be ensured.

Most commenters supported ground-water monitoring as a 

release detection method in common use that has successfully detected 

leaks. One commenter expressed reservations about the method, saying 

that released product can migrate away from monitoring wells around an 

UST system and claimed some problems with Florida's program. EPA 

continues to acknowledge that the method is not completely risk-free and 

also believes that it provides a level of protection equivalent to the 
other allowed release detection methods. In addition, not allowing 

ground-water monitoring in the rule would force states like Florida that 

depend primarily on ground-water monitoring to completely revamp their 

programs, thus disrupting established and effective programs, delaying 

implementation, and unnecessarily increasing expenditures because of the 

replacement of all the existing wells with other equipment. Therefore, 

in consideration of the limitations discussed below, EPA has retained 

ground-water monitoring as an option in the final rule.

(b) Limitations. The limits on well placement in the 

proposal restricted this method to areas with the water table 20 feet or 

less below the surface and with soils having a hydraulic conductivity of 

at least 0.01 cm/sec. Also, the wells had to be placed within the 

excavation zone. These restrictions were intended to ensure rapid 

detection by minimizing the distance that a release must move between 

the UST and the monitoring point and minimizing the time taken to move 

that distance. Ground-water monitoring was also limited to use with 

products that are immiscible in water and lighter than water so the 

product can be detected by the monitors.

o Depth to Ground Water

Many commenters believed that the proposed 20-foot maximum 

depth-to-ground-water restriction was too stringent and requested that 

this maximum value be increased or even deleted entirely from the final 

rule. Others agreed with the proposed rule. The Agency still believes, 

however, that increasing the allowable maximum depth would increase the 

volume of the release that could occur before detection. Detection of 

releases is also slower and less certain with deeper wells because 

subsurface geology can inadvertantly direct product away from the 

monitoring wells, even if they are located close to the UST system. EPA 

research conducted since the proposal suggests that 20 feet is the 

maximum depth to ground water that will permit detection in 30 days when 

the hydraulic conductivity is 0.01 cm/sec (Notice of Availability; 53 FR 

10403). Also, once a release is detected by a deeper well, corrective 

action will be more difficult and costly because more product has been 

released. Therefore, EPA has retained in the final rule the 20-foot 

depth-to-ground-water restriction when ground-water monitoring is used 

as the sole release detection method. If this method is used as a 

supplemental device to another approved form of leak detection or as a 

release investigation method, EPA encourages the use of these wells at 

greater depths or in less permeable soils.
o Placement of Monitoring Wells

Commenters also objected to the proposed requirement that 

the monitoring wells intercept the excavation zone. One commenter noted 

that this requirement could result in existing tanks being punctured 

during drilling of the well. Another commenter said such a requirement 

violates some existing state laws intended to prevent contamination. 

The Agency shares this concern as one expressed by numerous regulators 

in the field. Apparently, not all owners and operators of existing USTs 

know the orientation and dimensions of their UST system, not all well 

drillers have the equipment to find the exact location of their UST, and 

errors in well installation can occur even when the placement of the UST 

is known.

Although a slight increase in the allowable distance 

between the UST and the well may result in slightly larger releases 

before detection, EPA decided that this was preferable to the 

catastrophic release that would occur if a tank were punctured. Today's 

final rule has been revised to require that the monitoring wells or 

devices be placed within the excavation zone or as close to the 

excavation zone as is technically feasible. This change also applies to 

new tanks although placing the wells in the excavation zone should 

rarely be technically infeasible.

The soil hydraulic conductivity limitation is retained in 

the final rule and will have to be met whether the well is placed 

outside or inside the excavation zone. Thus, the revision on well 

placement is not a major change because wells are allowed outside the 

excavation zone only when the well is in close proximity to the UST 

system, the soil is very porous, and released product can move quickly 

to the well. If the soil outside the excavation zone cannot meet the 

conductivity requirement, the well must be placed inside the zone.

o Immiscible in Water

The proposed rule required that the regulated substance be 

immiscible in water and have a specific gravity less than one in order 

to use ground-water monitoring. These requirements were needed to 

ensure that released product would float on top of the water table, 

where it could be detected by the monitors. The Agency has retained 

these requirements in the final rule but notes that ground-water 

monitoring is intended for use with gasoline and other substances that 

are, in fact, slightly soluble in water. Thus, the immiscibility 

requirement does not exclude substances which are in fact slightly 

soluble. The slight solubility will not interfere with rapid detection 

because most of the product is still floating on top of the water table 

where the monitor can sense it. For example, gasoline has been 

successfully detected by ground-water monitoring in state programs such 

as Florida's.

(c) Design Specifications. In the proposed rule, EPA did 

not include any design specifications for the monitoring wells and 

networks because site conditions vary widely throughout the U.S., and 

the Agency wanted to allow the implementing agencies and owners and 
operators as much flexibility as possible in designing the wells and 

monitoring network to fit the site. Commenters suggested that the rule 

should contain more specific requirements and restrictions. EPA 

continues to believe that tailoring the wells and the network to the 

specific conditions will result in better release detection, so few 

specific requirements can (or should) be included at the national level. 

In addition, most states, such as Florida, that are relying on groundwater monitoring as the preferred release detection method have already 

included detailed design specifications in their UST programs.

However, upon further review of the proposed limitations 

and capabilities on ground-water monitoring and the experience using 

this method in Florida, and other areas, the Agency did decide that 

three well-design criteria should be added to the final rule to prevent 

common problems. First, if the top of the water table is above or below 

the screened interval of the well, then the free product floating on top 

of the water table will not be able to enter the well and be detected by 

the monitor. For this reason, today's final rule requires that the 

monitoring well screen must allow entry of regulated substance into the 

well under both high and low ground-water conditions. Second, the final 

rule requires that screening be designed to prevent migration of soil or 

filter pack into the well, which would clog the screen and prevent 

product from entering and being detected. The third criterion added to 

the final rule is the requirement that the wells be sealed from the 

surface to the top of the filter pack, which will prevent possible 

contamination by hydrocarbons washed from the surface by rain water that 

might cause a false alarm or mask a future release.

(d) Sensitivity of Monitor. The last limitation included 

in the proposed rule to ensure rapid detection using ground-water 

monitoring was a performance standard requiring that the monitoring 

equipment be capable of detecting the presence of at least one-eighth of 

an inch of free product on top of the ground water. This value was 

selected because it is the maximum performance that manufacturers 

continue to claim can be achieved by existing automated monitoring 

equipment. This requirement was intended to apply both to automated and 

manual monitoring techniques. Some commenters wanted to make the 

standard more stringent by reducing the criterion of one-eighth of an 

inch of free product in the well to one-sixteenth of an inch or by 

replacing it with nonquantitative terms such as detection by "sheen" or 

by human sight or smell. The commenters felt that the Agency did not 

give enough justification for selecting the 1/8-inch value and that it 

is essentially defining the volume of an acceptable release.

The Agency reiterates that the 1/8-inch requirement was 

selected as the performance standard because it is the sensitivity of 

existing automated equipment, not because it is an acceptable release. 

A preliminary EPA analysis indicates that several commercial devices can 

detect 1/8 inch of product on top of a water table (Notice of 

Availability; 53 FR 10403). To set a performance standard that is more 

stringent than can be met by existing technology would eliminate use of 

this method, which has proven effective in several local UST programs. 

The Agency considered allowing only manual methods of collecting and 
analyzing ground-water samples, which may be more sensitive than 

automated monitors; however, manual methods are very subjective and can 

only be conducted intermittently, whereas automated methods can be 

continuous and are less subjective. Therefore, today's final rule 

retains the 1/8-inch performance standard, and both manual and automated 

monitoring are acceptable.

(7) Interstitial Monitoring (§ 280.43(g)).

Interception barriers and interstitial monitoring were two 

methods of release detection allowed in the proposed rule. Because they 

are two distinct methods used to detect releases, they were treated 

separately. These methods and the requirements that were proposed for 

them were discussed in detail in the preamble to the proposed rule (52 

FR 12735-12739). Commenters were in favor of allowing these methods but 

suggested changes to some of the requirements. In response to comments 

on several technical issues raised in the proposal concerning both 

methods, EPA has changed some of the technical requirements. Based on 

these comments, the final rule has consolidated the requirements for 

both methods into one section, eliminated the use of soil/clay liners, 

and added a requirement to prevent interference with effective cathodic 

protection.

Section 280.41 of the proposed rule allowed monitoring 

between an UST and two types of impermeable barriers as two separate 

release detection methods. The first method, proposed in § 280.41(f), 

allowed monitoring for liquids in the unsaturated zone between an UST 

and an interception barrier immediately below it. Interception barriers 

are basically partial excavation zone liners: they are located 

immediately below the UST and come only part of the way up the sides of 

the excavation pit. The second method, proposed in § 280.41(h), allowed 

interstitial monitoring between an UST and a secondary barrier that 

surrounds the entire UST system. These barriers are not the partial, 

catch basin-type of barriers allowed under the first method. These 

barriers are either integral to the tank system design itself (e.g., 

double-walled tanks or pipes) or they are located within the UST 

excavation area along the bottom and sides of the pit and present a 

barrier between all parts of the UST system and the environment (e.g., 

flexible membrane pit liners).

Using either of the above barrier-type methods, the 

interstitial space between the tanks and the barrier can be monitored by 

a variety of devices designed to detect a variety of changes in 

operating conditions (e.g., pressure changes with double-walled tanks or 

presence of liquid or gaseous product in the interstitial space between 

the barrier and the UST system). Because improper design can make these 

systems ineffective, the proposed rule included a number of design 

criteria to ensure effectiveness as a release detection method.

(a) Consolidation of Sections. The proposed rule included 

a set of general performance standards and design limitations for each 

method to ensure effective detection of released product. The 

requirements for the two methods were essentially the same. Despite 
their similarity, they were included separately in the proposed rule to 

make it clear that they are two distinct proposed methods and that both 

are acceptable means of detecting releases. These two methods were not 

intended to prevent releases, but were intended to contain releases long 

enough to direct the regulated substance to a monitor for detection; EPA 

intended that release prevention be covered in the UST design and 

installation sections of the rule (52 FR 12735-12739).

Today's final rule has been reorganized so that the 

performance requirements for both of these methods are discussed in a 

single section (§ 280.43(g)). The Agency has decided to eliminate the 

separate and duplicative sections in the proposed rule on interception 

barriers and interstitial monitoring because this appeared to be a 

source of confusion to some commenters. This is only an organizational 

change, not a deletion of a possible release detection method, and does 

not change the substantive intent of the proposal. The consolidated 

design and performance limitations for both methods remain as proposed 

with the exception of the changes noted below.

(b) Performance Standard. The proposed rule required that 

the interstitial monitor between an UST and a secondary barrier be 

capable of detecting any release from the UST into the interstitial 

area. One commenter objected to this wording because it requires that 

the interstitial monitor would be capable of detecting any release, no 

matter how small. The Agency disagrees with the commenter and believes 

that interstitial monitors should be capable of detecting a release into 

the interstitial area. The available data on monitor performance 

indicates that they are very sensitive and will, in fact, be able to 

detect the type and size of release that is likely to occur from a 

secondarily contained UST system. Ideally, EPA agrees with the 

commenter that a performance standard should be included in the rule to 

define the sensitivity of interstitial monitors. The data are 

insufficient, however, to determine a performance standard. Secondary 

containment with interstitial monitoring is a very sensitive release 

detection method and is believed to provide maximum protection of human 

health and the environment, and the Agency did not want to eliminate it 

from the rule for lack of a specific performance standard. Therefore, 

the final rule continues to require that interstitial monitors be 

capable of detecting a leak from any portion of the tank that routinely 

contains product.
(c) Soil/Clay Liners. The Agency solicited comments on 

the performance of barriers for purposes of UST release detection (52 FR 

12736, 12739). The subject the Agency received the most comment on was 

the question of the use of soil/clay liners. Some commenters approved 

of the use of soil/clay liners but suggested that these liners needed 

more stringent limitations. Other commenters recommended that these 

liners not be allowed in the final rule because they are not impermeable 

to all gasoline constituents. Recently completed studies by EPA's 

Office of Solid Waste on the effectiveness of soil/clay liners compared 

to synthetic liners (Notice of Availability, 53 FR 10403), as well as 

information submitted by commenters on the proposal, have caused the 

Agency to delete this proposed technical option from today's final rule. 

This means that barriers constructed from native soils or artificially 

treated soils (for example, bentonite-sealed soils) are excluded from 

use under the revised performance requirements for barriers. In 

general, soil/clay barriers are not being allowed because there is 

enough evidence about the inadequate performance of these materials as 

reliable barriers to question their reliability for release detection 

purposes.

(d) Interference with Cathodic Protection. Several other 

commenters noted that barriers that completely line the excavation might 

interfere with the cathodic protection system. For example, flexible 

membrane barriers are usually non-conductive and could electrically 

isolate the anodes from the tank system, preventing the flow of 

protective current. The Agency agrees that this could be a problem 

although no failures of this type have been reported. A general 

requirement has, therefore, been added to the rule, stipulating that 

barriers must not interfere with cathodic protection (§ 280.43(g)). EPA 

believes this can be met in most cases simply by ensuring that the 

components of the protection system are placed inside the barrier 

system.

(e) Compatibility of Liner with Product. The proposed 

rule contained a requirement that the secondary barrier be compatible 

with the regulated substance to prevent the product from eroding the 

integrity of the liner over time, causing holes and possible releases to 

the environment (52 FR 12735, 12736, 12739). The Agency agrees with 

commenters who noted that a small amount of liner deterioration is 

inevitable. Accordingly, the wording of the proposed compatibility 

performance requirement in § 280.43(g) has been changed to indicate that 

some deterioration is permissible as long as it does not prevent the 

detection of a release. This requirement was revised to ensure that a 

basic level of compatibility is achieved and to make the owners and 

operators responsible for ensuring barrier materials (e.g., flexible 

membrane liners) are compatible with the product stored (see also 

§ 280.32).
(8) Other Methods of Release Detection (§ 280.43(h)).

As discussed in the preamble to the proposal (52 FR 12739-

12740), EPA has identified over 250 commercially available release 

detection devices. The Agency continues to believe that methods of 

detection other than the seven general methods listed in the rule may 

also be able to successfully detect releases under certain 

circumstances. Thus, the proposed rule allowed the use of other methods 

of release detection if they were approved by the implementing agency as 

no less stringent than one of the other methods listed in the rule. 

Commenters generally preferred that any mechanism for approval of a new 

method be at the federal level (discussed in more detail below). The 

final rule, however, retains the approval mechanism as proposed but 

provides an additional mechanism for allowance of other methods. A new 

method may be used if it can detect a release of 0.2 gallon per hour or 

150 gallons within a month with a PD of 95 percent and a PFA of 5 

percent. The Agency felt that adding the second alternative mechanism, 

one which is self-implementing, will provide consistency among methods, 

offer additional flexibility for owners and operators to choose new or 

improved technologies of equivalent protection to those specifically 

allowed in the rule, and spur innovation.

(a) Other Methods Approved by Implementing Agencies. The 

specific methods EPA proposed have demonstrated effectiveness in the 

field and are already in extensive use. An important purpose for 

including these methods was to make it clear that their use was allowed 

for meeting the proposed release detection requirements and under what 

conditions they could be used. The Agency intends to continue to 

develop and provide information helpful to the implementing agencies in 

evaluating new methods. EPA will also continue to foster identification 

and development of new methods. Although the Agency wants to allow new 

methods, it was also concerned that, to protect human health and the 

environment, they be limited to the methods that are at least as 

stringent as the methods proposed. Therefore, the proposed rule 

included a mechanism to allow the use of a new release detection method 

if the owner or operator could demonstrate to the implementing agency 

that the method could detect releases before they migrated beyond the 

excavation zone as effectively as one of the methods already in the 

rule.

Generally, commenters agreed with the need for allowing new 

methods but most felt it should be a federal approval process conducted 

by EPA, not by the implementing agency as proposed. The commenters were 

opposed to delegating approval authority to the implementing agencies 

because the lengthy and repeated (for each state or local agency) 

approvals would discourage method development and because state and 

local officials do not have the knowledge to make these evaluations. 

All of the commenters felt that the approval mechanism would be more 

efficient at the federal level, where approval could be granted one 

time, rather than 50 times, by means of an approved list or a revised 

regulation.
As stated in the proposal, the Agency wants to foster 

innovation and development of new release detection methods and to allow 

them to be implemented quickly (52 FR 12739). Therefore, the Agency is 

concerned that the development and publication of a federal list of 

approved methods or a revised regulation, as suggested by some 

commenters, would take too long. The Agency could decide, at some 

future time, to revise the final regulation to add new general methods. 

The Agency is convinced, however, that allowing approval by the 

implementing agency, including those at the state and local level, will 

enable a new method to be used more quickly because the implementing 

agencies would not have to wait for a federal approval before a method 

could be implemented. In addition, the precedent set when a new method 

passes an evaluation in one implementing agency should facilitate 

succeeding reviews by other agencies.

Implementing agencies are developing UST programs quickly, 

and the Agency's primary concern is to meet their needs as rapidly as 

possible. The Agency's research on release detection methods will 

provide important information to state and local agencies for use in 

their decisions on which release detection methods to allow. The Agency 

will continue to encourage private sector evaluation of new release 

detection methods and the exchange of this information with the 

implementing agencies. In addition, as discussed below, the Agency is 

providing another, self-implementing alternative for use of methods not 

explicitly included in the rule.

In addition to the reasons given above, a federal approval 

listing process or a revised regulation would not ease some of the 

problems that commenters foresee with delegating approval to the 

implementing agencies. EPA's inclusion of methods in the final rule, or 

its subsequent endorsement of a new method, does not automatically make 

the method acceptable in a state because states or local governments 

may, under their own authority, impose release detection requirements 

more stringent than EPA's. Each state can review each method and decide 

whether or not to allow it. In fact, a number of state and local 

agencies are already implementing their own UST programs, and some of 

these programs have more restricted lists of approved methods than the 

federal rule. Thus, the final rule retains the proposed option of 

approval of other methods by implementing agencies.

The standard for implementing agency approval has been 

changed in the final rule to make it consistent with other changes in 

the rule. The revised ground-water monitoring standard no longer 

requires that the monitoring wells pass through the excavation zone. As 

discussed in section IV.D.2.d.6. above, the Agency did not believe that 

this requirement was necessary to protect human health and the 

environment. The revised method can no longer detect a release before 

it migrates beyond the excavation zone, making the standard for 

implementing agency approval meaningless. To retain the consistency 

between this section and the method requirements, the standard for 

comparing new and existing methods in the final rule has been revised. 

The standard now specifies that methods approved by the implementing 

agency must be as effective as one of the other methods allowed in the 

rule. Methods are considered to be equivalently protective if they can 
detect a small release as quickly and reliably as other methods included 

in the rule. This change is consistent with changes in § 

280.42(b)(5)(i) (see section IV.D.2.c.2. of the preamble).

(b) Other Methods That Meet a Performance Standard. The 

Agency included in the final rule a second mechanism by which a new 

release detection method can become approved. A new method may be used 

to meet the release detection requirements if it can be demonstrated to 

detect a leak rate of 0.2 gallon per hour or 150 gallons within a month 

with a PD of 95 percent and a PFA of 5 percent. This performance 

standard for alternative release detection methods contains two 

equivalent leak rates, and the owner or operator may demonstrate 

compliance with either format. Although external monitoring methods are 

capable of detecting very small releases, it is more difficult to 

demonstrate that they meet a small hourly release rate than a larger, 

though equivalent, volume. The Agency was concerned that, if only the 

0.2 gallon per hour release rate was included in this performance 

standard, manufacturers of new and effective external monitoring 

equipment or experimental methods would be discouraged from developing 

the methods or would be unable to demonstrate compliance to the 

statisfaction of the implementing agency. As discussed previously, EPA 

wishes to encourage development of new release detection methods.

Unlike the performance standards for the specific allowable 

release detection methods, the PD and PFA values for the performance 

standard for new alternative methods are effective immediately. As 

discussed above in section IV.D.2.a.5., compliance with the 

probabilities applicable to all methods is delayed for two years. This 

delay was included in the final rule to allow manufacturers time to 

modify existing methods, which are already in wide use, and develop the 

required documentation of performance while still providing the 

immediate release detection needs required in the rule. These allowable 

methods were identified in the rule because they are widely used and 

expected to work well, often without significant improvements. New 

alternative methods, however, should be developed from the beginning to 

meet the most stringent performance requirements. In addition, the 

Agency was concerned that only requiring a leak detection capability of 

0.2 gallon per hour could be interpreted to allow imprecise methods such 

as inventory control to be used alone for the first 2 years of the 

program. Methods such as ATGS can already operate almost to the 

required probabilities of detection and false alarm, whereas inventory 

control cannot come close to these levels, and to allow its use alone 

even for 2 years would be harmful to human health and the environment.

The evidence gathered by EPA from laboratory evaluations 

and field experience indicates that the methods specifically proposed 

(except inventory control) should be able to meet this performance 

standard now or in the near future (see discussions above for each 

method). As new methods use this mechanism to become approved, this 

will ensure consistency of performance among new methods. The net 

effect of including this alternative in the final rule is to move closer 

to the general performance standard for all methods considered desirable 

by many commenters (see discussion in section IV.D.2.a.4. above).
The addition of this alternative will have the effect 

desired by commenters and EPA of spurring innovation and development of 

new technology for release detection because there is now a specific and 

measurable goal for manufacturers to work towards. In particular, this 

approach will provide flexibility to develop new release detection 

methods for unusual UST systems such as bulk tanks, for which current 

methods are inappropriate or expensive. This approval mechanism will 

have the additional advantage of allowing a new method proven to meet 

the standard to be used without any approvals in states which allow this 

approval mechanism.

This approach also clarifies what minimium equivalent 

performance must be demonstrated to the implementing agency under the 

other approval procedure for new methods (see preceding section). EPA 

did not, however, want to make this performance standard the only means 

by which a new method could become approved because it may not be 

possible to easily determine a leak rate for some methods within the 

next few years, particularly external ones. Such methods can still be 

very effective at detecting releases and the Agency wants to encourage 

the development of sensitive methods. If method developers can 

demonstrate to the implementing agencies the sensitivity of their 

methods in ways other than leak rates, then they should be able to do 

so. For these reasons, the performance standard approach to approving 

new methods is included in the final rule in addition to, not in place 

of, the proposed mechanism requiring review by the implementing agency.

e. Methods of Release Detection for Piping (§ 280.44)

The general release detection requirements for pressure and 

suction lines are discussed in section IV.D.2.b.2. of this preamble. 

This section discusses the performance standards for those required 

release detection methods. 

One commenter noted that piping and tank release detection 

methods should be separated because not all tank methods apply to piping 

and vice versa. A separate section addressing piping release detection 

methods has been added to the final rule to address these concerns. 

Separating the methods for tanks and piping allows owners and operators 

greater flexibility in designing a system. For example, at a station 

with extensive piping, installing flow restrictors and conducting an 

annual tightness test for the piping and using vapor monitoring for the 

tanks may better protect the environment and cost less than installing 

vapor monitoring for both the tanks and piping.

The proposed rule required either continuous monitoring 

devices or automatic shutoff devices on all pressurized lines as well as 

a line tightness test in conjunction with scheduled tank tightness 

tests. The proposed rule established a leak rate for the automatic 

shutoff device and indirectly required line tests to meet the tank test 

standard (0.1 gallon per hour with a PD of 99 percent and a PFA of 1 

percent) but set no other performance standards. The Agency requested 

comment regarding the field performance of pressurized piping release 

detection methods (52 FR 12744). Commenters noted that additional 
performance parameters should be provided in the rule, such as detection 

limits and line operating characteristics. The Agency agrees and has 

accordingly added further specifications to the piping release detection 

methods allowed in the final rule to ensure that they meet these minimum 

performance standards. Thus, probabilities of detection and false alarm 

have been added for the automatic line leak detectors and line tightness 

tests; and (for reasons explained earlier) the effective date of these 

probabilities is delayed for 2 years. Because leak rates depend on the 

pressure in the line, the Agency agreeded with commenters suggesting 

that the minimum performance standards for line leak detectors, which 

operate by detecting changes in line pressure, should be specified in 

terms of the line operating pressure. Each of the piping release 

detection methods is discussed below.

(1) Automatic Line Leak Detector (§ 280.44(a)).

The proposed rule required that the automatic shutoff 

device be capable of detecting and shutting off a release of at least 2 

gallons per hour. This value was selected based on manufacturers' 

claims. Most commenters felt that the performance standard suggested in 

the supplemental notice (52 FR 48638) of 0.1 gallon per hour with a PD 

of 99 percent and a PFA of 1 percent was too stringent, and that 2 

gallons per hour was below the detection level of flow restrictors.

The performance standard in the final rule for automatic 

piping release detection methods (including flow restrictors, shutoff 

devices, and interstitial or external monitors) has been set at 3 

gallons per hour at 10 psi with a PD of 95 percent and a PFA of 5 

percent. The 3 gallons per hour value and the probabilities were 

selected based on a study conducted by EPA's Office of Research and 

Development of the behavior of pressurized lines, an evaluation 

performed and submitted by a commenter, and manufacturers' written 

claims. The value of 10 psi was also selected because it is the 

pressure at which a typical line leak detector operates. A manufacturer 

can test a device at any convenient operating pressure and 

mathematically convert the results to 10 psi to determine if the device 

meets the performance standard. As discussed elsewhere in today's 

preamble (section IV.D.2.a.5.), the effective date of the PD and PFA is 

delayed for 2 years following promulgation.

The final rule also requires that an automatic line leak 

detector be capable of checking for releases hourly and either restrict 

or shut off flow of product or be equipped with an audible or visual 

alarm. The Agency intends the term automatic line leak detector to 

include a wide variety of devices that meet the standard including 

automatic shutoff devices, automatic flow restrictors, continuous 

interstitial monitors, continuous vapor monitors, or continuous groundwater monitors. The hourly detection frequency was selected because 

pressurized lines can release large volumes of product quickly, so very 

frequent monitoring is necessary during operation to protect human 

health and the environment. The equipment currently on the market 

either operates continuously or conducts a test each time the pump is 

turned on to dispense product, provided several minutes have elapsed 
since the previous dispensing, so meeting this requirement should not be 

difficult. The Agency believes the operators must be alerted 

immediately to the presence of leaks in pressurized lines. To do this, 

a clear indication such as flow restriction or shutoff or an alarm is 

considered necessary.

The final rule also contains the requirement that all 

automatic line leak detectors be checked annually according to 

manufacturer's requirements. This requirement was added in response to 

commenters' concern that line leak detectors can malfunction or be 

overridden by unwise operators. The possible burden of an annual 

maintenance check is outweighed by the importance of detecting and 

stopping pressurized releases.

(2) Line Tightness Test (§ 280.44(b)).

The line tightness test that is required in the final rule 

annually for pressurized piping and every 3 years for American-style 

suction systems is part of the tightness test option that was proposed 

for the entire UST system. Work conducted at EPA's test laboratory in 

Edison, NJ, has demonstrated that line tightness test methods should be 

able to meet a performance standard of 0.1 gallon per hour with a PD of 

95 percent and a PFA of 5 percent with, perhaps, some minor 

modifications in procedure and equipment (see section IV.D.2.b.2.). 

Therefore, this performance standard has been adopted in the final rule. 

As discussed above and in section IV.D.2.a.5., application of the 

performance standard for line tightness testing has been delayed for 2 

years.

As discussed above, the performance standards for line 

release detection must be stated in terms of the line operating 

pressure. The value of 1.5 times the operating pressure was selected 

for the line tightness test because most operators are currently 

performing tightness tests at this pressure, it is the procedure 

recommended by NFPA 329 for hydrostatic testing, and it covers the range 

of line operating pressures, including suction lines. It should be 

noted that, for safety reasons, all line tightness tests should be 

performed at positive pressure, not a vacuum, even for suction lines. 

For example, most suction lines operate at 3 to 5 psi negative pressure; 

therefore, tightness tests should be conducted at about 7 psi positive 

pressure.

(3) Applicable Tank Methods (§ 280.44(c)).

In the proposed rule, six categories of tank release 

detection were allowed to meet the monitoring requirement for the "UST 

system," which included the associated underground piping. As discussed 

in section IV.D.1.a. above, the final rule now separates the release 

detection methods for tanks and piping because not all tank release 

detection methods can be used for piping and vice versa. As noted by 

commenters, some of the tank monitoring methods are in fact applicable 

to piping, such as vapor monitoring, 
groundwater monitoring, and interstitial monitoring, and the Agency 

wanted to include their use as an option for piping release detection. 

Therefore, the final rule allows monthly monitoring with one of the 

applicable tank monitoring methods if it is capable of detecting a 

release from the portion of the underground piping routinely containing 

product and meets the restrictions applicable to the use of those 

methods. This is one of the options for the monthly release detection 

requirement, in addition to the automatic line leak detector 

requirement.

f. Recordkeeping (§ 280.45)

The proposed rule required that all UST system owners and 

operators maintain records on the release detection systems required in 

the rule. The requirement to keep records of performance claims, test 

results, and equipment maintenance was included because of the 

importance of each of these activities in the successful detection of 

releases and in demonstrating compliance to the implementing agency. 

Commenters generally felt that the requirements were too burdensome and 

would be particularly difficult to achieve if the testing was done by a 

service company. The main areas of concern were the requirement to keep 

performance claims and the components of an adequate performance claim.

Today's final rule retains the recordkeeping requirements 

as proposed with two revisions. First, only release detection equipment 

permanently located on-site must have written documentation of 

calibration, maintenance, and repair on file. Second, manufacturers' 

schedules of calibration and maintenance for release detection equipment 

must be retained for 5 years from the date of installation.

The Agency required in the proposed rule that all UST 

system owners and operators maintain three types of records 

demonstrating compliance with the applicable release detection 

requirements: documentation of method performance monitoring results; 

and general operation, maintenance, and repair. It was felt that these 

records demonstrate that certain past events important to effective 

release detection using that method actually took place and could be 

used by implementing agencies to determine compliance (52 FR 12747). In 

general, commenters felt that the proposed recordkeeping requirements as 

a whole were too burdensome. The Agency believes, however, that the 

requirements are not particularly burdensome because many of the records 

will be supplied by manufacturers, sales personnel, or service people; 

not much paperwork is involved and the required records would generally 

be kept on file anyway; and paperwork will be added infrequently. In 

general, some records are needed to remind the owners and operators when 

maintenance is scheduled and to help them keep the equipment under 

warranty. Finally, properly maintained records are necessary to allow 

later analysis of the tank systems by either the owners and operators or 

the implementing agency in the event of a release investigation or 

system closure. Each of the individual requirements receiving comment 

or revised in the final rule is discussed below.
The requirement to maintain manufacturers' performance 

claims and justifications for 5 years was intended to encourage 

manufacturers to evaluate their equipment and develop documentation of 

the proof of performance and to cause owners and operators to review 

this information while selecting an appropriate release detection 

method. Many commenters expressed confusion over what these performance 

claims would be and were concerned that the owners and operators were 

being required to substantiate the claims. It was not the intent of the 

proposed or final rule to require the owners and operators to provide 

the proof of performance claims, only for them to ask for and acquire 

information from the manufacturer. In order to compete and successfully 

market equipment, the manufacturer will have to develop convincing 

documentation demonstrating that the release detection method meets the 

minimum performance requirements.

As discussed in the proposal preamble (52 FR 12719), there 

are several types of information that the manufacturer should include in 

this documentation and that the owners and operators should look for. 

The final rule does not require any specific information, however. EPA 

recognizes that the level of detail will vary by type of method and 

that, over time, manufacturers will develop standardized claims that 

will help guide the owners and operators. This requirement will place 

owners and operators in the position of having to review the claims and 

select a system that will meet regulatory requirements. Thus, owners 

and operators are responsible for achieving the goal of effective 

release detection and demonstrating to the implementing agency that the 

owners and operators have made an effort to comply with the regulation. 

For these reasons, this section of the final rule will remain unchanged 

from the proposal.

The proposed rule required that all records of calibration, 

maintenance, and repair be maintained by all owners and operators for at 

least one year. These are important procedures for the proper 

functioning of release detection equipment, particularly automated 

systems, and must be available for inspection to demonstrate that the 

system is working as well as it can. One commenter noted that the 

recordkeeping requirements would be difficult to meet for owners and 

operators who hire release detection services to do the monitoring. EPA 

agrees with this, and today's final rule states that this requirement 

applies only to owners and operators of equipment permanently located 

on-site. Owners and operators who hire release detection services need 

not retain the servicing records of their contractors. Owners and 

operators, however, must ensure that the service is performed well and 

according to specifications and will be responsible for the cleanup of 

any undetected releases.

Another addition to today's final rule that was not in the 

proposed rule is the requirement that any schedule of required

calibration and maintenance provided by the release detection equipment 

manufacturer must be retained for 5 years from the date of installation. 

This information should be provided by most manufacturers in the same 

brochures as performance claims; thus, this new requirement should not 

result in much additional paperwork. This requirement was added as a 

clarification to the final rule to remind owners and operators of the 
importance of maintaining these data. With this requirement, 

implementing agencies can verify that required maintenance and 

calibration were performed. Also, if ownership of a site is 

transferred, the new owner or operator will be able to understand and 

ensure that the proper schedule is maintained.

g. Other Release Detection Issues

(1) Release Detection Variances for Low-Risk Sites.

In the Supplemental Notice (52 FR 48641), EPA noted that 

protected tanks in some areas of the country may not require frequentto-continuous release detection. EPA requested comments on whether, 

within these less sensitive areas, variances should be allowed for 

protected tanks to conduct internal inspections or less frequent 

monitoring. EPA requested comment on the appropriateness of these 

alternative release detection approaches and under what conditions they 

might be used. There was little agreement among commenters on either 

issue, and no specific recommendations on how low-risk areas could be 

defined or identified at the federal level. The final rule does not 

include a release detection variance for low-risk areas because of the 

difficulty in operationally defining and implementing a variance 

procedure which adequately protects human health and the environment.

Commenters who supported the use of the variance felt that 

it would improve environmental protection by focusing resources on UST 

systems in higher risk areas. Commenters opposed to the variance noted 

that leaks can pose environmental problems even in low-risk areas. 

Their experience suggested that impermeable formations may actually have 

hidden fractures that allow product to reach deep ground water and 

necessitating expensive cleanup efforts. They further suggested that, 

under any circumstance, product leaks may pose an explosion hazard. 

These commenters also noted the difficulty of managing a variance 

process.

The Agency agrees with commenters who noted significant 

problems with a variance procedure. No commenters were able to suggest 

a manageable variance procedure given the size of the UST universe. As 

noted earlier in the preamble, defining sensitive or low-risk areas at 

the federal level is problematic (see section III. of today's preamble). 

Because the Agency could not develop reasonable criteria for granting 

variances on a case-by-case or prospective basis, no release detection 

variance is included in the final rule. Consequently, less protective 

detection options such as infrequent monitoring for protected tanks over 

10 years of age will not be permitted in any areas regardless of risk.
(2) Internal Inspection as an Alternative to Release Detection.

The Agency also considered the use of internal inspections 

as a substitute for release detection. EPA solicited comment in the 

December 23, 1987, supplement to the proposal on the use of internal 

inspections at low-risk UST sites. The Agency received many comments 

both for and against this option. In general, supporters of internal 

inspections believe that this would provide important information on the 

internal and external corrosion and the structural integrity of tanks. 

Some commenters specifically recommended allowing internal inspection as 

a release detection alternative at low-risk sites (e.g., sites that are 

not in vulnerable ground-water supply areas or in close proximity to 

surface waters and residential areas) while others supported its use at 

all UST sites. Schedules for conducting internal inspections, such as 

at periodic intervals (e.g., every 3 to 5 years; or ever 10 to 15 years) 

or based on tank age, were recommended by several commenters.

Reasons given by commenters not supporting this option 

included: (1) not all tanks are constructed with manways, (2) internal 

inspections are time consuming and would be cost effective only for 

larger (bulk) tanks, (3) internal inspections do not provide sufficient 

information on tank integrity, and (4) inspections are a safety risk to 

the inspector.

The Agency does not have sufficient data on the performance 

of tanks subject to internal inspection programs that would allow it to 

determine that such an approach without release detection would be 

protective of human health and the environment. The Agency is aware 

that internal inspections are widely used by owners and operators of 

bulk tanks for evaluating tank integrity. Based on insufficient 

information on the use of internal inspections with all USTs and the 

lack of industry consensus codes, however, the Agency has decided not to 

include this as a release detection alternative in the final rule.

E. Release Reporting, Investigation and Confirmation

1. Overview

Because UST systems are hidden from direct observation, 

suspected releases must be investigated to identify, or confirm, that an 

UST system is the source of a release. Monitoring results and other 

indicators in the environment are the only suggestions of a release. In 

general, corrective action cannot be started until the UST system and 

UST site are investigated and a release is confirmed.

The proposed rule required that all suspected releases be 

reported to the implementing agency (see proposed § 280.50). Suspected 

releases included: positive monitoring results from testing, monitoring 

and sampling, unusual operating conditions, and the discovery of 

regulated substances in the environment. All suspected releases had to 

be immediately investigated, unless the owner and operator elected to 

proceed directly to corrective action.
As discussed in the preamble to the proposed rule (52 FR 

12747-12751), the development and implementation of criteria and 

procedures to determine the appropriate circumstances to initiate, 

conduct and conclude the confirmation process can be technically 

complex. This situation is further affected by the fact that owners and 

operators are typically reluctant to begin what they consider to be the 

costly process of confirmation. Although this testing is inexpensive 

relative to corrective action costs, owners and operators typically want 

to avoid all unnecessary costs. The Agency's proposed release reporting 

and confirmation requirements were established in the belief that nearly 

all suspected releases must be investigated before conducting even more 

elaborate and costly abatement procedures. The first step was to 

quickly establish if the UST system is actually leaking. Prompt 

reporting of suspected releases also was proposed so that responsible 

authorities could take action to ensure that investigations are timely, 

properly designed and performed, and protective of human health and the 

environment.

The Agency proposed several alternative procedures for 

investigating suspected releases including: different combinations of 

tank and line tightness testing, inventory reconciliation review, 

testing of secondary containment, checking equipment operation, soil 

coring and analysis, and other methods specified by an implementing 

agency. Numerous comments were received in response to the proposed 

requirements. Most commenters took issue with the proposal's attempt to 

provide specific direction and guidance and suggested that even more 

details were needed to successfully implement this approach. For 

example, several commenters questioned how soil sampling results were to 

be interpreted and when the soil coring analysis and investigations 

could be accepted as definitive. In addition, commenters pointed out 

that the actual steps in confirmation are determined on a site-by-site 

basis. Other commenters were concerned with the discretion provided the 

implementing agencies in directing owners and operators in the 

investigation of off-site impacts.

As discussed elsewhere in today's preamble, EPA has 

received very encouraging information about the general efficacy of tank 

tightness testing. Also, it has become clear from comments and 

information received that tank tightness testing is the most prevalent 

technique now in use to determine if a suspect system is in fact 

leaking. Thus, tightness testing is a key confirmatory step in the 

final rule required of all owners and operators, unless they choose to 

immediately conduct an initial site investigation instead.

The fact that the overwhelming majority of release 

investigations are presently conducted using either a tightness test (as 

suggested by several commenters) or a small-scale site investigation has 

influenced the final rule as presented today. Accordingly, the five 

proposed investigation alternatives have been replaced with the 

requirement to use these two prevalent methods. Alternative methods 

that are no less stringent and are approved by the implementing agency 

are still allowed. Today's rule has been revised to more clearly 

establish the end point for investigation and confirmation procedures. 
These procedures end when a successful tightness test is obtained or 

when the data from environmental testing do not significantly exceed 

background levels. (However, these investigations may resume if 

additional evidence to the contrary is presented or is discovered.)

2. Section-by-Section Analysis

a. Reporting Requirements (§ 280.50)

The proposal (§ 280.50) required owners and operators to 

report to the implementing agency within 24 hours any monitoring results 

from any release detection methods specified in Subpart D that indicated 

that a release may have occurred. Also, the observation of any unusual 

operating conditions at the UST system that could be indicative of a 

release, as well as any indication of the presence of released 

substances in the environment surrounding the UST, had to be reported. 

The proposed requirement for the implementing agency to be informed 

early in the confirmation process was believed necessary so that the 

implementing agency would be assured that proper investigation 

procedures were used. Commenters generally responded that it is not 

necessary to report all suspected releases. They identified situations 

in which obvious false alarms would have to be reported, and conditions 

that would be disruptive to the operation of the facility. They pointed 

out that the large number of what would prove to be unnecessary reports 

could overwhelm the implementing agency.

The Agency acknowledges that some of the situations brought 

to its attention could indeed result in a significant number of false 

(or unnecessary) reports. For example, the erratic behavior of 

dispensing equipment may warrant further investigation before reporting 

because this behavior can be caused by more than just a leak in the 

line. Accordingly, the final regulation has been revised to allow 

owners or operators to verify the proper operation of their equipment 

before reporting a suspected release. If the faulty equipment is 

immediately repaired or replaced and further inspection fails to confirm 

the initial result, the incident does not need to be reported. In the 

case of inventory control, the rule now allows a second month of data to 

be collected to verify the possibility of a release before reporting. 

This does not mean that all inventory discrepancies must be confirmed by 

a second month's data. Under some conditions, it may be necessary for 

owners and operators to immediately report an inventory discrepancy. 

What level constitutes a suspected loss depends on the size of the tank, 

monthly throughput, and other operating practices. The appropriate 

action level must be worked out in advance of using this method.

Other situations such as the physical presence of the 

regulated substance or unusual concentrations of vapor still require 

immediate reporting. (The requirement for reporting soil concentrations 

of 100 parts per million or more has been removed because specific 

national action levels cannot be established for each affected medium; a 

more reportable condition is whether new contamination was found based 

on a change from earlier conditions at this site, rather than arbitary 
numerical standards and levels.) Failure to determine that an 

operational problem is caused by faulty equipment will also require 

reporting. In addition, as in the proposal, the Agency requires the

owners and operators to report off-site conditions that might indicate a 

release has occurred and that are brought to their attention by a third 

party. This is intended to expedite the process of quick identification 

of release incidents by giving the general public additional avenues to 

report their observations.

b. Investigations Due to Off-Site Impacts (280.51)

Under the proposed rule, the owner and operator had to 

investigate suspected releases that were indicated by off-site impacts 

and as required by the implementing agency. The unintended 

interpretation of this requirement was that the implementing agency 

could direct the owner and operator to conduct off-site investigations 

in response to the discovery of off-site impacts. Commenters strongly 

objected to this proposed requirement because they felt that it was 

improper to conduct investigations on property not under their control 

and because of the apparent wide discretion given the implementing 

agency in deciding what confirmation steps are needed in an off-site 

investigation.

The final rule includes revised language that restates the 

requirement so it is clear that owners and operators must investigate 

their own UST system and site when requested by the implementing agency 

and based on the discovery of off-site impacts. The potential for 

environmental damage is too great to allow the source of a release to go 

unidentified and unchecked. Limiting the investigation to the on-site 

UST system should minimize problems suggested by commenters associated 

with the investigation of releases on property owned by other parties. 

The Agency did not intend that owners and operators, under these 

regulations, must conduct investigations on property belonging to 

others. In the final rule, the investigation has been limited to the 

determination of whether the owner and operator's UST system is the 

source of the off-site impact. If regulated substances have been 

released from an owner and operator's system, as determined by an onsite investigation and confirmation, then they will be responsible for 

any necessary corrective action, whether on- or off-site.
c. Release Investigation Procedures (§ 280.52(a) and (b))

As discussed in the proposal preamble (52 FR 12748-12751), 

the Agency considered three approaches to release confirmation: 

detailed, step-by-step procedures; confirmation directed completely by 

the implementing agency; and a basic, but not detailed, set of 

requirements. The first approach was rejected because it is not 

feasible to identify and address all possible types of releases and site 

conditions in the regulation. The second approach was rejected because 

implementation of release investigation would be delayed until 

implementing agencies had the time and resources to determine the 

appropriate methods for each individual site and because owners and 

operators would generally delay action until their responsibilities were 

determined by the implementing agency. Thus, the Agency selected the 

third approach as providing sufficient guidance as well as flexibility.

To implement this approach, the proposed rule provided five 

specific procedures for release investigation. Any one procedure could 

be used depending on the preference of the owner and operator and the 

way in which a suspected release was identified. These procedures were: 

(1) performing a site investigation under the direction of the 

implementing agency; (2) checking the interstitial area of a secondary 

containment system; (3) in the case of a failed tightness test, checking 

inventory records, retesting of each portion of the system, and 

analyzing soil samples; (4) in the case of an inventory discrepancy, 

performing tightness tests and analyzing soil samples; and (5) 

performing any other investigation procedure that is no less stringent 

than those above if approved by the implementing agency. This selection 

of release investigation procedures was intended to address all possible 

situations and allow investigation to begin quickly even in the absence 

of guidance from the implementing agency (although such an interaction 

was considered most desirable).

Most commenters disagreed with the proposed approach, 

particularly the degree of authority given to the implementing agencies. 

Some of these commenters requested more specific guidance on 

investigation procedures, particularly what to do given certain findings 

and when to end an investigation. The specific investigation technique 

receiving the most comment was the soil coring requirement. Commenters 

felt it was an expensive and difficult process, the results of which are 

not definitive in confirming a release as there are many sources of soil 

hydrocarbons other than a current release. The proposed rule was also 

unclear about what actions should be taken based on the results of soil 

sampling. This requirement was proposed to be combined with the 

tightness test because it was believed that tightness tests might not be 

determinative and could not detect very small releases. This 

requirement was deleted in the final rule because it is now apparent 

(see discussion below) that tightness testing is a reasonably sensitive 

and reliable method. Soil sampling and analysis may still be part of 

the site investigations process as discussed in section (3). below.
(1) Timing of Release Investigation and Confirmation.

The Agency required in the proposal that all suspected 

releases be investigated within seven days of initial reporting. 

Commenters were equally divided on whether this period was too long or 

too short. The Agency recognizes that there are some situations, such 

as the presence of product in the environment, where an immediate 

response to a suspected release is required. In other cases, such as 

when relatively small inventory discrepancies appear, greater time 

intervals may be allowed. The rule has been changed to recognize this: 

a second month of data collection is allowed for inventory control 

confirmation; seven days are allowed for testing of the tightness of 

tanks and lines; and 24 hours are allowed for checking the operation of 

monitoring and dispensing equipment.

(2) Tightness Test (280.52(a)).

Since proposal, the results of three studies have 

influenced the Agency's thinking on effective release investigation 

procedures. The evaluation of 25 tightness test methods at the EPA 

Office of Research and Development's laboratory at Edison, New Jersey, 

(53 FR 10403) indicates that current equipment, operated with some 

procedural modifications, should be able to detect leaks as small as 

0.10 gal/hr (see section IV.D. of this preamble for further discussion 

of tightness testing and these results). In California, a state with a 

large UST population and an active UST program (and in numerous other 

state and local programs), tightness testing is often the preferred 

approach to release investigation. The new information on the causes of 

release from UST systems (discussed earlier in this preamble) 

demonstrates that the most common sources of releases are pressurized 

piping and loose fittings and bungs on top of the tank, which only leak 

during tank overfill. The easiest way to detect releases from piping is 

a line tightness test, and the overfill-type of tank tightness test will 

identify bad fittings on top of the tank. For all of these reasons, the 

Agency has concluded that tightness testing is a much more effective 

method of release investigation than was known at proposal, is often the 

most logical test with which to investigate a suspected release, and is 

currently the most practiced confirmation tool nationwide.

Based on the above conclusion that tightness testing is the 

most effective first step in release confirmation, the Agency revised 

the final rule to ensure that the appropriateness of this method is 

highlighted. Consequently, the sections of the proposed rule presenting 

the several alternative investigation procedures have been deleted from 

the final rule. (In doing this, EPA agrees with several commenters that 

some of these procedures were incomplete and unnecessary on a sitespecific basis.) In their place are two alternative investigation 

steps, the first of which is to conduct tightness tests to determine the 

integrity of the tank and piping. If the test results indicate there is 

a leak from a portion of the UST system that routinely contains product, 

the owner and operator must stop the leak and begin corrective action 

(releases from other portions of the UST system are addressed in 

reporting and cleanup of spills and overfills in § 280.53). If the 
tightness test indicates that the UST system is not leaking and there is 

not evidence of environmental contamination, the final rule does not 

require further actions of the owner and operator. However, if evidence 

of environmental contamination is still present and unexplained, the 

second alternative investigation step must take place. The second step 

requires conducting an initial site investigation (see section (3) 

below).

This revised approach is intended to provide clearer 

guidance and definitive end points as was requested by several 

commenters. In addition, tightness testing is a familiar technique for 

many owners and operators and is the most readily available and 

inexpensive investigation procedure. Therefore, by emphasizing its use 

as the primary release investigation procedure, many owners and 

operators will more likely begin investigation quickly on their own 

without waiting for the implementing agency to direct them. This 

capability of quick response, plus the sensitivity of tightness testing 

and its ability to pinpoint all sources of a leak, will minimize the 

potential damage to human health and the environment from a suspected 

release. Moreover, tightness testing is frequently the first step in 

corrective action to determine what must be done to stop a release. 

Thus, making it a part of release investigation will be cost effective 

for owners, operators, and implementing agencies.

(3) Site Check (§ 280.52(b)).

The proposed rule (§ 280.51(a)(1)) allowed owners or 

operators to investigate suspected releases by conducting an initial 

site investigation of the UST site under the direction of the 

implementing agency. The final rule retains this option as the second 

step in the release confirmation process. The site assessment 

requirements in the original proposal, however, have been significantly 

modified to provide owners and operators greater flexibility in 

consideration of different site conditions. The requirements have also 

been modified to be more consistent with the assessment activities 

required under the closure and corrective action provisions of the final 

rule.

The initial site assessment allowed under the proposed 

release confirmation provisions was intended to be similar to the 

investigation performed under the closure and corrective action 

provisions. The objective of each of these assessments is to measure 

for the presence of released regulated substances and provide a 

preliminary indication of the need for and scope of further corrective 

action activities. They are not intended to define the full extent or 

location of soils contaminated by a release. Despite this similarity in 

purpose, however, the proposed rule specified different sampling methods 

and assessment techniques. As a result, a number of commenters 

expressed confusion concerning the nature and scope of the assessment 

and requested more specific guidance on investigative procedures. 

Therefore, to clarify the rule's objectives and ensure that the results 

obtained from each type of assessment are comparable, similar site check 
requirements have been incorporated into the release confirmation, 

closure, and corrective action subparts of the final rule.

The site investigation allowed under the proposed rule had 

to be conducted under the direction of the implementing agency. As 

noted above, a number of comments criticized the degree of authority 

given to the implementing agency under these provisions. EPA agrees 

that the proposal did not give owners and operators adequate guidance 

for determining the objectives and goals of the site investigation. 

This could have resulted in wide variations in the nature and scope of 

the site assessments conducted under the proposal and in inconsistencies 

in the resulting data and their interpretation. The proposal also could 

have inadvertently required the implementing agencies to commit 

significant resources to the management of site assessments given the 

large number of assessments, projected to be conducted over the next 5 

to 10 years. Therefore, the final rule allows the owner and operator to 

plan, select methods, and conduct the initial site check. These 

changes, however, do not diminish or restrict in any way the authority 

of the implementing agency to participate in the planning and 

performance of site investigation activities of the owner and operator. 

These changes will allow the implementing agency to determine the scope 

of their involvement in the site investigation program and, at the same 

time, avoid unnecessary and potentially costly delays in the 

implementation of each assessment by the owner and operator.

The final rule does not require the owner and operator to 

use a particular type of measurement method or assessment technique. A 

number of commenters questioned the applicability and effectiveness of 

the investigative procedures discussed in the proposed rule, and 

suggested other methods that may be equally effective in various sitespecific situations. EPA agrees that a given sampling method or 

measurement technique may not provide representative results for all 

types of regulated substances and site conditions. For example, soil 

gas sampling may not be appropriate where the regulated substance 

contains compounds that are non-volatile or where the local geology and 

hydrology significantly restrict the movement of the volatilized organic 

species.

To address this problem, the final rule requires the owner 

and operator to measure for the presence of regulated substances in the 

area where contamination is most likely to be present. Any factors that 

may affect the identification of the source or presence of contamination 

must be considered in order to ensure that the assessment will provide 

accurate and reliable results. The rule specifies the factors deemed to 

be the most important in selecting the measurement method and in 

conducting the initial site check.

Measurements must be taken in the area surrounding the UST 

system where contamination is most likely to be present. Samples may be 

collected from any depth as long as they are taken where contamination 

is most likely to have migrated or accumulated given the specific 

characteristics of the site and the regulated substance. Most regulated 

substances will tend to migrate down and, as a result, the Agency 

believes that samples taken at depths below the UST system's suspect 
components will generally satisfy the requirements of this subsection. 

The contaminants in some regulated substances, however, may float on the 

water table or dissolve in the ground water. Consequently, the nature 

of the regulated substance and the depth to ground water around the UST 

system are important factors to be considered when developing an 

assessment plan.

The owner and operator may also find it necessary to 

conduct the initial check in an area that extends outside of the 

excavation zone of the UST system. Although the Agency believes that 

sampling in the excavation zone will generally provide the most accurate 

information about the presence and source of contamination at an UST 

site, it may not be possible to identify the precise location of the 

excavation zone or gain reasonable access to the areas adjacent to the 

tank and piping due to interfering structures. In addition, samples 

taken from the excavation zone will not give any information concerning 

the extent of contamination. Where contamination poses an imminent 

threat to human health and the environment on adjacent property, it may 

be more appropriate to take samples at or near the site's property line 

that is ajacent to the off-site point of impact. For example, seepage 

of liquid or vapors into occupied residences or into drinking water 

supplies may necessitate sampling at the adjoining property line so that 

corrective action activities can be expedited. In such cases, the 

mitigation of contamination in the soil or ground water around the 

building or well may be more important than first identifying the cause 

of the contamination, particularly where there are several possible 

sources of suspected releases.

The specific factors identified in the final rule were 

selected to ensure that representative assessment information is 

obtained during release confirmation. Consideration of these factors by 

the owner or operator is deemed by EPA to be the minimum requirements 

for adequately evaluating the area surrounding the tank. They are not 

intended to be exhaustive nor should they be given equal weight at all 

sites. The importance of each of the factors must be evaluated 

carefully in view of the regulated substances suspected of being present 

and the specific conditions at the site.

d. Reporting and Cleanup of Spills and Overfills (§ 280.53).

In the proposal, the Agency specified that spills and 

overfills which resulted in the release of a regulated substance meeting 

or exceeding the reportable quantity (RQ) under CERCLA (40 CFR 302), or 

spills and overfills of petroleum exceeding 25 gallons or causing a 

sheen on surface water, must be reported to the implementing agency with 

24 hours. The proposed approach has been maintained in the final rule.

In the preamble to the proposed regulation, the Agency 

requested comments on the appropriateness of the reporting cutoff of 25 

gallons for aboveground releases of petroleum to land and surface water. 

Commenters were divided on this issue. Many supported the 25-gallon 

cutoff while some requested that it be raised to much higher levels and 

a few requested that it be lowered. The Agency has retained the 
proposed reporting levels while allowing individual state and local 

implementing agencies the ability to select other amounts under certain 

conditions. In all cases, the spill or overfill must be immediately 

contained and cleaned up, and, if it is not, then it must be reported to 

the implementing agency. The point at which a report must be submitted 

to the implementing agency is an administrative convenience, and the 

Agency intends to leave some discretion to the states on this area.

The Agency believes that spills often occur at many of the 

facilities in this regulated community. In fact, knowledgeable members 

of the regulated community have reported to EPA that spills and 

overfills are the second most common source of release to the 

environment. This conclusion is based in part on observations made 

during tank removal of obviously contaminated soil around areas of the 

tank where spills might be expected to occur. This soil contamination 

can be caused by emptying fill hoses onto the ground after delivery, 

either by accident when the hose is disconnected from the tank or on 

purpose when the tank is inadvertently overfilled and the hose cannot be 

drained into the tank. Although any one incident may or may not result 

in a significant threat at a particular site, the Agency has concluded 

that the repeated occurrence of these releases over time does represent 

a serious threat to human health and the environment.

The concern about spills reporting is that spills appear to 

occur very frequently, although generally in small quantities. The 

requirement to report all spills, regardless of their size, could cause 

the implementing agency to be overwhelmed with reports of numerous small 

spills that do not represent a significant threat to human health and 

the environment. The Agency believes very little threat is posed by 

smaller spills if they are contained and immediately cleaned up, 

including contaminated surface soils. The installation of catchment 

basins required in Subpart B in the final rule should reduce the number 

of releases to the environment, the cost of cleanup for owners and 

operators and the number of incidents where reporting is necessary.

The Agency has retained the proposed RQ approach to 

indicate to the owner and operator when reporting is necessary. For 

petroleum, this approach requires reporting of aboveground releases to 

land in excess of 25 gallons, and of aboveground releases to water if 

the result is an oil sheen on the water, in accordance with the 

requirements of 40 CFR Part 110. The rationale for this was provided in 

the preamble to the proposal. The Agency also recognizes that, in some 

cases, it may not be possible to immediately clean up a spill of less 

than 25 gallons. When this occurs, the owner and operator is required 

to report the spill to the implementing agency.

A spill or overfill resulting in the release of a hazardous 

substance to the environment must be reported if the volume equals or 

exceeds its RQ as defined under CERCLA (40 CFR 302). The RQ for a 

particular hazardous substance may result in a volume that is less than 

25 gallons. The Agency feels it is necessary to place tighter controls 

on hazardous substances because of their generally greater threat to 

human health and the environment. An additional discussion of this 

issue is provided in section VI.A. of this preamble. The release of a 
hazardous substance equal to or in excess of its RQ must also be 

reported to the National Response Center immediately (rather than within 

24 hours) under sections 102 and 103 of CERCLA and to appropriate state 

and local emergency response authorities under Title III of SARA. The 

requirements of today's rule do not change the responsibilities of 

owners and operators to meet the requirements of these other EPA rules. 

Thus, in the case of a spill or overfill of a regulated hazardous 

substance from an UST, the owner and operator is subject to two 

reporting requirements. The impact of additional reporting, however, is 

minimal because the goal of The National Response Center is essentially 

to inform local implementing agencies. This will already have been done 

when the owner or operator fulfills the requirements in today's rules.

Although reporting triggers have been established for 

aboveground releases, this does not relieve the owner and operator of 

the responsibility to undertake all other appropriate elements of the 

corrective action process under Subpart F for any aboveground release, 

regardless if it is more or less than the reportable quantity.

F. Release Response and Corrective Action for UST Systems Containing 

Regulated Substances

1. Background

Release response and corrective action for UST systems 

include activities to investigate, report, abate, and remedy releases of 

regulated substances into the environment. To ensure that necessary 

steps are taken to protect human health and the environment at all sites 

discovered to have a release, EPA proposed steps that all owners and 

operators must take quickly to identify and reduce any immediate health 

and safety threats posed by releases. In addition, proposed 

requirements mandated the investigation and amelioration of the longterm threats to human health and the environment posed by releases that 

have migrated beyond the UST system to contaminate surrounding soil and 

ground water. Long-term actions would begin after an implementing 

agency determined that additional corrective action was needed to 

protect human health and the environment. This determination was to be 

made on the basis of data gathered and submitted by the owner and 

operator and a site-specific exposure assessment performed by the 

implementing agency. Finally, the proposal distinguished between 

releases of petroleum and hazardous substances by establishing separate 

corrective action requirements for them in different sections of the 

proposed regulations (Subpart F for petroleum and Subpart G for 

hazardous substances).

Today's final rule builds upon this proposed approach, but 

also reflects several important changes that respond to concerns raised 

by commenters on the proposal:

oThe Agency has consolidated the proposed requirements for 

petroleum and hazardous substances into one section of the 

final rule in Subpart F. This consolidation deletes the 
extensive duplication of requirements in the proposal 

caused by separating them into two sections.

oThe proposed basic framework and most of the proposed 

requirements for the initial abatement steps required at 

all release sites are retained in the final rule. Changes 

have been made, however, to some of the proposed 

requirements in response to public comments. These changes 

are intended to clarify the owner's and operator's 

responsibilities for identifying and addressing the initial 

health and safety threats posed by releases.

oThe final rule retains the proposed requirements for long-term 

corrective actions, which follow a site-specific approach 

for establishing clean-up target levels. This section of 

the rule has been amended, however, to clarify that the 

owner and operator may proceed, under certain conditions,

with corrective action before a corrective action plan has 

been approved by the implementing agency.

oIn response to concerns raised by several commenters, EPA has 

revised several of the proposed requirements to clarify the 

responsibilities of owners and operators. Some changes 

clarify when owners and operators must initiate specific 

corrective action steps, such as detailed soil and groundwater investigations, particularly in the absence of clear 

direction from the implementing agency. Other changes more 

clearly identify what owners or operators must do to carry 

out their responsibilities in such areas as the initial 

site investigation, detailed investigations for soil and 

ground-water contamination, and free-product removal.

oThe final rule clarifies the requirements concerning the 

public participation process for corrective action. The 

final rule emphasizes the need to ensure public access 

(primarily through existing state procedures) to 

information pertaining to specific corrective actions.

In the preamble to the proposed UST corrective action rule, 

EPA requested comments on several corrective action issues: the general 

scope of the proposed requirements; how explicitly these requirements 

should be detailed in the rule; whether the proposed minimum site 

investigation requirements were appropriate; and the desirability of the 

proposed site-specific approach to setting cleanup goals for UST sites. 

EPA also requested comment on the definition of free product, the 

adequacy of existing state administrative authority for public 

participation in corrective action, and corrective action requirements 

for tanks containing a mixture of regulated substances (see 52 FR 12678-

12683 and 12751-12757). EPA received comments on all these issues, as 

well as on other issues not raised specifically by the Agency in the 

proposal.

Although many commenters believed that the proposed 

corrective action regulations were essentially sound, EPA received a 
wide array of responses on key issues. For example, although several 

commenters disagreed with the Agency's proposed requirements for sitespecific cleanup standards, others supported this approach. Several 

general concerns were repeatedly raised by numerous commenters as they 

commented on specific proposed requirements: what must be done and by 

whom, how much discretion should be granted to the implementing agency 

to change specific requirements, and what minimum objectives must be met 

during the various steps in the corrective action process. As noted 

previously, these general concerns have prompted EPA to make several 

changes in the final rule, and clarifications appear below in the 

following two subsections of today's preamble.

General concerns raised by commenters are briefly discussed 

and responded to in the next subsection of this preamble (section 

IV.F.2.):

o Site-specific approach to corrective action;

o Discretion for implementing agencies;

o Clarification of owner and operator responsibilities; 

and

oConsolidation of requirements for petroleum and hazardous 

substances.

Following the discussions of these issues, section IV.F.3. provides a 

section-by-section analysis that more specifically addresses the changes 

made to the proposed requirements in the development of today's final 

corrective action rule, and the highlights of the public response that 

prompted these revisions.

2. Major Issues Influencing the Final Rule

a. Site-Specific Approach to Corrective Action

In the proposed rule, EPA selected a site-specific approach 

for setting cleanup target levels for long-term corrective actions. 

These cleanup levels would be keyed to data obtained from a detailed 

site investigation of soil and ground-water contamination by the owner 

and operator, and from a site-specific exposure assessment conducted by 

the implementing agency. As discussed in the preamble to the proposal 

(52 FR 12680-12682), EPA believed this approach would allow implementing 

agencies the necessary flexibility to develop their own programs or 

implement existing programs. Given the size of the regulated community 

and the diversity of UST environmental settings, EPA concluded that the 

site-specific approach was the most effective framework for enabling 

implementing agencies to assess the extent of necessary corrective 

action in individual cases.

The final rule retains EPA's selection of the proposed 

site-specific approach for UST corrective action requirements. A 
central element of this site-specific approach is the establishment of 

site-specific cleanup standards that adequately protect human health and 

the environment. In the preamble to the proposed rule (52 FR 12678-

12683), EPA asked for comments on whether the long-term cleanup 

requirements of the UST corrective action rule should be established: 

(a) on the basis of national cleanup standards, with a variance 

provision; (b) to reflect ground-water classification schemes where 

national standards would apply in some settings, and site-specific 

cleanup levels in others; or (c) as site-specific standards as proposed.

EPA received comments that supported each of these options, 

with suggestions on how to implement the preferred option. Most 

commenters who supported establishing national cleanup standards 

believed that standards expedite cleanups and provide greater 

consistency in cleanup goals. They did not provide EPA with 

information, however, that showed that the use of national cleanup 

standards would substantially hasten the UST corrective action process 

or relieve administrative burdens. In addition, EPA is not convinced 

that the use of a single cleanup standard for UST cleanups will achieve 

greater consistency in the protection of human health and the 

environment than a site-by-site exposure assessment approach. At the 

present time, the Agency's assessment of UST corrective action shows 

that cleanup results are generally limited by the available technology 

and particular site conditions rather than by a cleanup standard. EPA 

also believes that the site-specific exposure assessments for UST 

releases required in today's final rule can be streamlined so that they 

will not delay corrective action, as some of these commenters feared. 

The Agency intends to work with implementing agencies to develop methods 

to streamline site-specific exposure assessments without diminishing 

protection of human health and the environment.

Some commenters supported the use of a ground-water 

classification system for UST corrective action decisions. As discussed 

earlier in today's preamble, however, EPA has concluded that developing 

a classification system at the federal level is extremely difficult and 

unworkable. EPA leaves to the discretion of implementing agencies the 

choice of whether to establish or incorporate existing ground-water 

classification systems to assist in their UST corrective action 

decisions. The Agency notes that the required investigations at UST 

sites and a site-by-site approach for UST corrective action will likely 

incorporate many of the same factors used in establishing a ground-water 

classification system.

In developing today's final rule, EPA noted that the 

majority of commenters preferred the proposed site-specific approach. 

The primary reasons cited were that this approach best accommodates the 

diversity of UST release situations and also reduces, in the aggregate, 

the cost of compliance. EPA notes, however, that its decision to 

promulgate a site-specific approach to long-term UST corrective action 

does not preclude states from establishing cleanup standards in their 

own UST corrective action programs. The Agency recognizes that some 

states already have elected to develop and use statewide cleanup 

standards, sometimes in conjunction with site-specific exposure 

assessments as part of a variance procedure.
b. Discretion for Implementing Agencies

The proposed corrective action rule afforded UST 

implementing agencies considerable discretion and flexibility in 

developing their own UST corrective action process. For example, EPA 

proposed language--such as "unless directed to do otherwise by the 

implementing agency" and "or as directed by the implementing agency"--to 

indicate that these agencies could add their own requirements or 

instruct an owner and operator to bypass certain requirements on a caseby-case basis. EPA felt that the diversity of UST settings and release 

situations required the implementing agency to have flexibility in 

tailoring many aspects of the corrective action response so that 

different releases could be cleaned up effectively and efficiently.

EPA received comments regarding the appropriate level of 

discretion provided to the implementing agencies. Some commenters 

warned that vague rule language could lead to arbitrary requests by the 

implementing agency; others suggested that EPA curtail the implementing 

agency's authority by issuing more detailed requirements. Several 

commenters were concerned about delays in site cleanups that might ensue 

because of additional requests by implementing agencies. Another 

suggestion was to expand the implementing agency's discretion to require 

the UST owner and operator to start a site cleanup before a corrective 

action plan is finalized.

In response, EPA has revised the final rule to clarify 

which elements of the UST corrective action process are mandatory and 

which are discretionary. As a result, the final rule mandates the 

response requirements that must be followed for all releases (§ 280.61), 

the investigation and cleanup requirements that are mandatory unless 

otherwise directed by the implementing agency (§§ 280.62 and 280.63), 

and the additional site-characterization and cleanup steps that may be 

required of UST owners and operators if certain site conditions exist or 

that may be required by the implementing agency (§§ 280.64 through 

280.66). EPA notes, however, that section 9008 of RCRA enables state 

and local regulation to be more stringent than the federal UST program. 

Thus, even if EPA removed discretion from the federal rules, EPA would 

not have the authority to prevent implementing agencies from imposing 

more extensive requirements than EPA under state or local law.

Commenters expressed concerns that cleanup of soil and 

ground water may be delayed due to lengthy reviews of the corrective 

action plans by the implementing agencies or by uncooperative owners and 

operators. In response, EPA has made two changes in the final rule. 

First, EPA has added the phrase "as appropriate" preceding the list of 

factors that the implementing agency must consider when reviewing a 

corrective action plan in § 280.66(b). This change makes it clear that 

the implementing agency need not formally consider all these factors if 

the agency determines analysis of these factors is not necessary to 

ensure protection of human health, safety, and the environment. Second, 

EPA has provided that owners and operators may begin cleanup of soil and 
ground water before their corrective action plan is approved by the 

implementing agency subject to conditions described in § 280.66(d).

In addition, under existing law, EPA or authorized UST 

implementing agencies can intervene to respond to clean up releases from 

UST systems. Under section 9003(h)(2) of RCRA, EPA and states under 

cooperative agreement are authorized to step in and take corrective 

actions for releases of petroleum from USTs in situations including the 

following: (1) the owner or operator fails to comply with the 

established cleanup schedule; (2) there is a need to take emergency 

action; (3) the cost of a corrective action exceeds the resources 

supplied by the financial responsibility mechanism provided by the owner 

or operator; or (4) the owner or operator is insolvent. For a release 

from a hazardous substance UST, EPA has the authority under CERCLA to 

respond. States are not provided such authority under CERCLA, but may 

have their own authorities under state law.

c. Clarification of Owner and Operator Responsibilities

Many commenters expressed the opinion that the proposed 

rule was difficult to interpret with respect to what had to be done and 

by whom to comply with the federal requirements. EPA agrees with these 

commenters that the language of the proposed rule was sometimes unclear 

regarding the specific responsibilities of UST owners and operators. 

The Agency, therefore, has revised the final rule to make clearer which 

elements of the corrective action rule are mandatory and which are 

discretionary.

EPA has concluded that the following basic steps are 

required to ensure an effective response to every release: rapid

notification that a release has occurred; investigation to mitigate 

fire, explosion, and vapor hazards; preventing further release of the 

regulated substance from the leaking UST system; and removing free 

product from the environment. These steps are required of every owner 

and operator in response to an UST release; implementing agencies may 

not change these requirements.

Similarly, EPA believes that the following initial site 

investigation and abatement steps are usually necessary to protect human 

health and the environment: estimating the nature and quantity of the 

release; removing as much of the regulated substance from the UST system 

as necessary to prevent further release to the environment; and 

gathering information about the locations of wells, subsurface sewer 

lines, and populations surrounding the release site. Thus, the final 

rule holds UST owners and operators responsible for these actions unless 

the implementing agency directs them to do otherwise in response to 

site-specific considerations.

The baseline requirements for initial release response and 

corrective action are covered in §§ 280.61 through 280.63 of the final 

rule. As noted above, the requirements of § 280.61 in the final rule 

describe mandatory initial response measures to be taken by UST owners 
and operators without exception. All UST owners and operators are 

responsible for meeting the requirements of §§ 280.62 and 280.63, unless 

the implementing agency directs them to do otherwise. Sections 280.64 

and 280.65 address those requirements for which owners and operators are 

responsible if certain site conditions exist. Section 280.66 describes 

soil and ground-water cleanup steps that may be initiated by the owner 

and operator or required at the direction of the implementing agency.

d. Consolidation of Corrective Action Requirements for Petroleum and 

Hazardous Substances

In the preamble of the proposed rule, EPA requested 

comments on whether the corrective action requirements for petroleum 

USTs (Subpart F) and hazardous substance USTs (Subpart G) should be 

integrated into one subpart or should remain separate (52 FR 12678). 

All commenters responding to this request favored the integration of 

Subparts F and G; they differed only in their suggestions to EPA on how 

to combine the two rules.

Today's final rule has consolidated into Subpart F all the 

corrective action requirements for releases from underground storage 

tank systems storing substances regulated by Subtitle I. The title of 

this subpart has been revised to make clear that it addresses both 

release response and corrective action activities. As can be inferred 

from the new title, an appropriate response to a release, particularly 

those small in size that were caught quickly and remedied, may not need 

to include long-term corrective action, if the initial response measures 

adequately protect human health and the environment.

The general applicability sections of the proposed 

petroleum and hazardous substance requirements (proposed § 280.60 and § 

280.70, respectively) have been replaced with a single new section. 

This revised section states that where RCRA Subtitle C corrective action 

requirements apply to UST releases at permitted RCRA facilities, 

Subtitle I corrective action requirements will not apply. EPA has added 

this provision to avoid possible duplication of requirements.

The initial abatement requirements have been retained in 

the final rule. In response to commenters who preferred the more 

detailed language used in proposed Subpart G, the Agency has carried 

forward the language emphasizing immediate action to prevent further 

releases and the containment of visible releases to the environment. 

The principal change in the initial abatement requirements provides 

owners and operators and implementing agencies greater discretion for 

determining the need for and timing of contaminated soil removal and the 

authority to decide appropriate soil management alternatives on a siteby-site basis.

The proposed rule for hazardous substance USTs had no 

separate section comparable to the proposed petroleum rule's 

requirements for free product removal. By merging Subparts F and G, EPA 

extends the free product removal requirements to all regulated substance 

releases, including removal requirements detailing precautions and other 
measures to follow during recovery operations. EPA recognizes that 

detection and removal of some hazardous substances can be far more 

difficult than removal of petroleum free product, especially in areas of 

complex hydrogeology. The Agency believes, however, that the free 

product removal requirements allow implementing agencies sufficient 

flexibility to consider factors that complicate the detection and 

removal of free product and to adjust the pace of actions to remove free 

product accordingly.

Both proposed rules had requirements governing additional 

investigations and the cleanup of contaminated soils and ground water at 

UST release sites. The final rule also contains these requirements in 

§§ 280.65 and 280.66, which are discussed in more detail later in the 

next subsection of this preamble.

Both proposed rules contained reporting requirements. The 

hazardous substance rule, however, required additional specific 

reporting items, such as likely migration routes and proximity to 

population centers. These additional reporting items have not been 

retained in the initial site investigation requirements of Subpart F 

because they are largely duplicative of the reporting requirements 

contained within final § 280.63, which governs initial site 

characterization. Moreover, implementing agencies continue to have the 

authority to require the reporting of additional specific information 

should the need arise.

The public participation requirements of both rules have 

been combined into a single section of the final rule.

3. Section-by-Section Analysis

In writing the final rule, EPA revised proposed §§ 280.60 

through 280.66 to clarify the release response and corrective action 

steps. Most of the changes are editorial, prompted by concerns or 

confusion expressed on the part of commenters. Some substantive 

changes, however, were also made in response to public comments. The 

following sections discuss in detail the changes made to the proposal as 

reflected in today's final rules. Issues raised by commenters on the 

proposed requirements and the Agency's consideration of these issues are 

also briefly discussed.

a. General (§ 280.60)

Proposed § 280.60 applied the corrective action 

requirements of Subpart F to all UST systems except those exempted by 

statute or regulation. Owners and operators of tank systems for which 

other subparts of the proposed technical standard are deferred were 

nonetheless required to comply with the Subpart F requirements in 

response to confirmed releases.

In the final rule, EPA has added language to clarify the 

applicability of Subtitle C or Subtitle I requirements to USTs at RCRA-
permitted facilities and to avoid potential overlap in regulatory 

authority. Section 280.60 of the final rule reflects the fact that the 

Subtitle C corrective action requirements under the authority of RCRA 

3004(u) will apply to many releases from UST systems located at RCRApermitted facilities, regardless of the regulated substance stored. For 

USTs not covered by 3004(u), including facilities without a final RCRA 

permit, Subtitle I corrective action standards will apply to releases 

from all petroleum and hazardous substance tanks covered under Subtitle 

I. UST corrective actions underway at facilities having interim status 

under RCRA may be subject to review under the RCRA corrective action 

program during the development of a final permit, and these ongoing 

corrective action activities may be incorporated into the facility's 

RCRA permit.

b. Initial Response and Reporting Requirements (§ 280.61)

Proposed § 280.61 (initial abatement requirements and 

procedures) has been separated into three new sections in the final 

rule: initial response (§ 280.61), initial abatement measures and site 

check (§ 280.62), and initial site characterization (§ 280.63). These 

sections, plus free product removal (§ 280.64), encompass the first 

phase of the UST corrective action process. As with the proposal, EPA 

intends these final requirements to achieve three goals: (1) to bring 

UST release sites under control with respect to immediate health and 

safety hazards; (2) to stabilize the site so that contamination will not 

worsen as investigations and potentially applicable long-term cleanup 

plans are considered; and (3) to be self-implementing, in that these 

measures emphasize the responsibility of the owner and operator to take 

quick action without awaiting direction from the implementing agency. 

Thus, §§ 280.62 through 280.64 in the final rule represent the baseline 

release response and corrective action requirements that are mandatory 

for all UST owners and operators and all releases, unless the 

implementing agency directs otherwise. The rule has been reformatted to 

make this clearer. The initial response requirements of § 280.61 are 

mandatory for all owners and operators and all releases without 

exception. In addition, §§ 280.60 through 280.64 have newly added 

reporting sections. The new placement of these reporting requirements 

clarifies the owner's and operator's responsibilities with respect to 

the timing and content of the required reports.

The final requirements of § 280.61 for initial response and 

reporting are essentially identical to those proposed. The primary 

difference is that the wording has been changed to make unambiguous the 

response required within 24 hours. These initial actions include: 

reporting the confirmed release to the implementing agency; taking 

immediate steps to prevent further release to the environment; and 

mitigating fire, explosion, and vapor hazards. EPA recognizes that, in 

some cases, it may not be possible to complete these steps within 24 

hours. For example, it is sometimes easier to confirm that a release 

has occurred than to identify the precise location of the release from 

the UST system. Similarly, it may take longer than 24 hours to 

adequately vent hazardous vapors from building. In revising this 
section, however, EPA emphasizes the potential urgency of a release and 

the responsibility of the owner and operator to quickly respond.

c. Initial Abatement Measures and Site Check (§ 280.62)

In order to clarify the on-site management steps that EPA 

believes are necessary to abate hazards and stabilize the site, the 

Agency has grouped initial abatement requirements into § 280.62. Two of 

the requirements in this section are carried forward from those in 

proposed Subpart G. First, § 280.62(a)(1) requires removal of the 

regulated substance from the tank as "necessary to prevent further 

release to the environment." EPA has added this phrase to acknowledge--

as some commenters pointed out--that some situations may not require 

complete removal of product from the tank (e.g., if the release is 

clearly demonstrated to be from one tank that is part of a multiple tank 

system). Second, § 280.62(a)(2) carries forward the requirement to 

visually inspect aboveground releases or exposed belowground releases 

and to prevent further migration of the released substance into 

surrounding soils and ground water (e.g., by using sorbents and berms to 

control the flow of product).

Section 280.62(a)(3) has been added to clarify EPA's 

proposed requirement to "mitigate fire and safety hazards." EPA agrees 

with commenters who noted that these hazards may persist or reappear 

beyond the initial response phase and, thus, must be monitored and 

remedied throughout the cleanup process. The new requirement also 

emphasizes that, if present, these hazards may require mitigation both 

within and beyond the boundaries of the UST site (e.g., in subsurface 

sewer lines or nearby buildings).

The requirement in proposed § 280.62(a)(4) to remove 

"visibly contaminated soil from the UST excavation zone" has been 

deleted. EPA received many comments on this proposed requirement. Most 

commenters expressed confusion regarding the definition of visible soil 

contamination and other concerns related to the appropriate timing and 

extent of soil removal. Commenters identified cases where a strict 

interpretation of the requirement (e.g., removal of slightly discolored 

soils) would translate into aggressive soil removal that would be 

unnecessary, technically infeasible, and very costly. Some commenters 

noted that extensive soil removal at UST sites could exacerbate problems 

of the nation's limited landfill capacity, if these soils were taken 

off-site for disposal. Other commenters suggested that soil removal or 

treatment (beyond that which is needed to address immediate health and 

safety hazards) should be considered as part of the long-term plan for 

corrective action. Many commenters suggested that EPA consider various 

in situ or on-site treatment methods as alternatives to immediate 

removal and disposal of contaminated soils.

EPA agrees with these commenters. In particular, EPA is 

concerned that requiring immediate and extensive excavation of 

contaminated soil may transfer contamination to other media (e.g., air), 

may transfer risk from one site to another, or may spread contamination 

at the release site beyond its existing extent. These outcomes are 
inconsistent with EPA's objective to protect human health and the 

environment. Further, EPA did not intend to preclude consideration of 

alternative on-site or in situ treatment methods.

As a result, EPA has created a new § 280.62(a)(4) to 

clarify the objectives of soil management that must be undertaken during 

the initial phases of corrective action. The new requirement states 

that UST owners and operators must remedy hazards posed by contaminated 

soils that are excavated or exposed as a result of release confirmation, 

site investigation, abatement, or corrective action measures. These 

hazards include vapor threats and potential leaching of contaminants. 

EPA believes this new requirement addresses concerns raised by 

commenters by more clearly stating the scope and the objectives of 

initial soil management.

In contrast to the proposed requirement for soil removal, 

EPA has not prescribed a specific management method. The final rule 

does, however, require that any exposed soils be managed as necessary to 

remedy hazards such as those mentioned above. EPA expects there will be 

UST release situations where prompt soil removal and disposal may be the 

most effective option (e.g., where there are relatively small quantities 

of contaminated soil in urban areas having high potential for human 

exposure to vapors, and where excavation equipment is already on-site 

for use in investigating the tank system). In such situations, soil 

removal may be necessary to bring the site under control with respect to 

immediate threats and might also be adequate to complete cleanup at the 

site. In response to commenter's concerns that soil management not 

simply transfer risk, EPA has, however, added a new requirement to the 

rule. If the owner and operator choose to treat or dispose of 

contaminated soils, they must comply with applicable state and local 

requirements. (See also section VI.B. of today's preamble: Relationship 

to Other Agency Programs.)

EPA received comments regarding the explicitness of the 

proposed site investigation requirements for corrective action, as well 

as for release confirmation and tank closure activities. Some 

commenters requested more specificity; others pointed out the difficulty 

of prescribing uniform requirements for all sites. In response, EPA has 

revised the rule (adding new §§ 280.52(b), 280.62(b) and 280.72(a)) to 

make consistent the site investigation requirements for release 

confirmation, corrective action, and tank closure and to avoid potential 

duplication of these requirements within the rule. (See section 

IV.E.2.c. of this preamble for an explanation of these site 

investigation requirements.) EPA believes this revised statement of 

site check responsibilities, in conjunction with the new initial soil 

management requirements, addresses commenters' request for greater 

clarity concerning their investigation responsibilites without unduly 

restricting alternative investigative techniques.

EPA recognizes, however, that the primary hazard posed by

contaminated soil at some sites will be as a continuing source of 

ground-water contamination. EPA addresses this concern through the 

final requirements for site characterization and for delineating the 

extent and location of contaminated soils (§§ 280.63 and 280.65). As 
discussed later in this preamble, these investigation results must be 

considered by the owners and operators and by the implementing agency 

with respect to site-specific exposure potential and effects on groundwater resources. EPA believes that, in some cases, it may be preferable 

to treat contaminated soil on-site or in situ. The Agency is preparing 

technical information that will help owners and operators and 

implementing agencies assess the potential hazards posed by contaminated 

soils and alternative methods to treat or dispose of them.

Section 280.62(b) in the final rule states that owners and 

operators are required to report their initial abatement steps to the 

implementing agency within 20 days of release confirmation. Some 

commenters noted that this time frame, which was proposed in 

§ 280.61(a)(5), could be interpreted to mean that EPA expected all the 

abatement measures in proposed § 280.61(a) to be completed within 20 

days. EPA expects that many of the initial abatement requirements can 

and should be completed within 20 days, but that some aspects of soil 

management and free product investigations and removal may require more 

time to complete. EPA has thus amended the wording to clarify that the 

objective of this provision is to require owners and operators to report 

their progress to the implementing agency.

d. Initial Site Characterization (§ 280.63)

Proposed as § 280.61(b), this requirement has been amended 

(and renumbered as § 280.63) to clarify the responsibility of owners and 

operators to collect and submit site information to the implementing 

agency. Several commenters noted that the same techniques can be used 

to confirm a release and to investigate contamination at a site. They 

expressed concern that important information gained while confirming a 

release or abating immediate hazards should also be included in the 

information submitted to the implementing agency. Section 280.63 in the 

final rule emphasizes this point and requires that owners and operators 

submit all pertinent information about the site and nature of the 

release.

In addition, §§ 280.63(a)(1) through (4) in the final rule 

describe the minimum site investigation requirements that the owner and 

operator must follow in the absence of other direction provided by the 

implementing agency. Section 280.63(a)(1) is unchanged from proposal, 

and it requires information on the nature and estimated quantity of the 

release.

Section 280.61(a)(2) continues to require owners and 

operators to submit information from readily available sources or site 

investigations regarding surrounding populations, subsurface soil 

conditions, climate, and land use (e.g., from sources such as U.S. 

Geological Survey maps, Soil conservation Saving maps, and local 

agencies). UST owners and operators are not automatically required to 

conduct surveys to collect this information if it is not already 

available.
In addition, two new requirements have been added to this 

section. First, information about water quality at all wells 

potentially affected by the release partially supplants the more general 

proposed requirement for ground-water and surface water sampling 

formerly in § 280.61(b)(3). As discussed in more detail in section 

IV.C.f. of this preamble--investigation for soil and ground-water 

cleanup--the proposed requirement to delineate the extent and location 

of dissolved ground-water contamination has been amended. The final 

rule requires full characterization of dissolved ground-water 

contamination if certain site conditions are met, or at the direction of 

the implementing agency. If nearby existing wells are potentially 

affected, however, EPA requires the owner and operator to immediately 

characterize their quality and use because they are potential human 

exposure points and because pumping at these wells can affect 

contaminant migration. Second, several commenters noted that subsurface 

sewer lines are often conduits for rapid migration of vapors or liquid 

product. Thus, EPA now requires owners and operators to submit 

information on the location of subsurface sewer lines (if any) at the 

site.

Section 280.63(a)(3) cross-references the site 

investigation requirements described earlier and requires the owner and 

operator to submit the results of this investigation as part of the site 

characterization report. This new section replaces proposed 

§ 280.61(b)(2), which required sampling of surface and subsurface soils. 

As described earlier, this change clarifies the investigation 

requirements and eliminates their possible duplication within the rule. 

The timing and reporting of this investigation is unchanged.

Section 280.63(a)(4) replaces proposed § 280.61(b)(3), 

which required sampling of surface and ground water at the site. This 

new section, in conjunction with § 280.65 (described in subsection f., 

below), reduces the ambiguity noted by some commenters regarding the 

scope of site investigations. In the final rule, EPA requires 

characterization of dissolved ground-water contamination when the 

following conditions exist: there is evidence that drinking water wells 

have been affected, free product is detected on the water table or 

within the aquifer; there is evidence that contaminated soil is in 

contact with ground water; or as directed by the implementing agency. 

Thus, the presence or absence of free product at an UST release site is 

one of the factors used to decide whether further investigations of soil 

and ground-water contamination are necessary. The requirement to 

investigate for free product is unchanged from the proposed 

§ 280.61(a)(6). The final rule simply requires owners and operators to 

submit, as part of the initial site report, their findings that 

establish the presence or absence of free product. EPA believes this 

action is warranted for several reasons:

oThe requirement reinforces for owners and operators the 

importance of the free product investigation;

oThe free product investigation requirement now also applies to 

releases from hazardous substance USTs, which may contain 
products that are denser than water and, therefore, may be 

harder to detect and locate; and

oThe conclusion that no free product is found provides another 

important consideration for the implementing agency as it 

decides if a corrective action plan will need to be 

submitted by the owner and operator.

EPA believes this synthesis of information from the initial 

site investigation is essential for owners and operators to begin to 

fully assess their cleanup responsibilities, and it provides the 

implementing agency with information to decide if a corrective action 

plan is necessary. Section 280.63(b) replaces the proposed requirement 

for reporting site investigation results. The new section clarifies 

that the information must be submitted in a manner that is clear and 

sufficiently detailed to demonstrate its applicability and technical 

adequacy, or in a format developed by the implementing agency to achieve 

these same goals.

e. Free Product Removal (§ 280.64)

In response to commenters, EPA has made minor revisions to 

the free product removal requirements. Commenters raised four issues: 

applicability, the definition of free product, the extent of removal, 

and the timing of removal. These issues are discussed below.

First, EPA agrees with those commenters who suggested that 

free product removal requirements similar to those proposed for 

petroleum releases should also apply to hazardous substance releases. 

The final rule's Subpart F merges the proposed rule's Subparts F and G 

to make free product removal requirements applicable to all releases.

Second, EPA has revised the definition of free product to 

clarify the scope of free product removal. Several commenters noted 

that, as proposed, the broad definition of free product could be 

interpreted to mean that removal requirements apply to product bound to 

soil particles or present as vapors. EPA notes that these forms of 

product are addressed, as appropriate, in other sections of today's 

final rule and has revised the definition of free product to more 

narrowly refer to a regulated substance that is present as a non-aqueous 

phase liquid (e.g., not dissolved in water). EPA has also deleted the 

reference to "floating" free product (from proposed § 280.62) to clarify 

that product more dense than water is also subject to the free product 

removal requirements.

Third, other commenters requested clarification on how much 

free product was required to be removed. In the final rule, the Agency 

has retained the phrase "maximum extent praticable" as the criterion for 

free product removal operations at UST release sites. EPA has not 

specifically defined maximum practicable removal because the extent of 

removal is largely determined by available technologies and sitespecific conditions. Consequently, EPA believes that implementing 

agencies should have the discretion to develop operational criteria for 

determining the presence of free product and the extent of its removal 
(e.g., product that flows in response to gravity or a minimum product 

thickness observed in wells). EPA has, however, added to the final rule 

a minimum objective for free product removal operations. This new 

requirement states that, at a minimum, free product removal systems 

should be designed to abate further migration of free product (i.e., 

beyond small seasonal or recovery-related fluctuations).

Fourth, several commenters offered their views about the 

appropriate timing of product removal. Most commenters agreed with 

EPA's proposal that free product removal operations should begin as 

quickly as possible, but cautioned that hasty and improperly conducted 

removal could spread contamination vertically at the site. In the final 

rule, EPA continues to require that removal begin as quickly as 

practicable (§ 280.62(a)(6)). Revised § 280.64(a) emphasizes, however, 

that free product removal must be conducted in a manner that minimizes 

the spread of contamination and that is appropriate to the hydrogeologic 

conditions at the site. EPA is aware, for example, of site conditions 

where trenching or vapor extraction to recover free product would be 

preferable to drawing down the water table--and the free product plume--

in order to collect and remove free product. EPA is preparing technical 

resource documents to assist implementing agencies in advising owners 

and operators about potential complications when removing free product. 

Similarly, in response to commenters concerns, EPA has extended the 

time period for owners and operators to report to implementing agencies 

concerning their free product removal from 30 to 45 days. This change 

will allow owners and operators more time to properly plan for free 

product removal, especially for removal operations involving dense 

product or at hydrogeologically complex sites.

In addition, some commenters requested EPA clarify 

permitting requirements for discharges from the product recovery system. 

Others suggested that EPA exempt UST cleanups from NPDES requirements 

or establish numerical limits for emergency permits. In response, EPA 

has revised § 280.64(a) to clarify that all discharges are to be 

properly treated, in compliance with applicable federal, state and local 

regulations. In addition, EPA is investigating methods to expedite, 

where applicable, the NPDES permitting process for discharges 

necessitated by UST corrective action.

f. Investigations for Soil and Ground-Water Cleanup (§ 280.65)

Proposed § 280.63 has been renumbered § 280.65 in the final 

rule. As proposed, this section required the owner and operator to 

investigate the extent of soil and ground-water contamination at an UST 

release site when the initial site investigation showed that 

contaminated soil remained at the site, or when the required soil 

removal showed that the released product or product from contaminated 

soil may have reached ground water. In addition, the implementing 

agency could direct the owner and operator to conduct such an 

investigation.

Several commenters requested that EPA clarify the minimum 

sampling requirements for these investigations. Other commenters 

suggested that these more extensive investigations be better coordinated 
with the soil and ground-water sampling required earlier in the 

corrective action process. One commenter noted that the phrase "product 

from contaminated soil" would be difficult to define and might be 

interpreted to require extensive investigation at virtually all sites. 

In addition, EPA recognizes that some amount of contaminated soil will 

be present at most UST release sites, but that the threat posed by this 

contamination will depend on several factors.

In response to these comments, EPA has revised this section 

to clarify the situations that trigger more extensive site 

investigations. EPA notes that the objective of these investigations is 

to support decisions concerning whether soil and ground-water cleanup or 

other corrective action measures are necessary at the site. 

Consequently, EPA has revised the rule to better relate these 

requirements to site-specific threats to ground-water contamination.

Final § 280.65 discribes three specific site circumstances 

requiring full for characterization of soil and ground-water 

contamination: (1) when release confirmation or previous corrective 

action measures indicate that ground-water wells may have been affected 

by the release, (2) when free product is found on the water table or 

within the aquifer, and (3) when any other site investigations show that 

contaminated soil may be in contact with ground water.

EPA recognizes that characterization of soil and groundwater contamination may also be necessary at sites where there are no 

"automatic triggers." Thus, the final rule retains the authority of the 

implementing agency to request an investigation. Final § 280.65(a)(4) 

clarifies that the implementing agency should consider the potential 

effects of contamination at the site in relation to nearby surface and 

ground-water resources when deciding whether further investigations are 

warranted. In particular, EPA expects that information required under 

§ 280.63 will provide implementing agencies with important information 

for determining if more extensive investigations are required.

In revising the rule, EPA sought to better tailor the 

investigation requirements to site conditions that pose a potential 

threat to ground-water resources. EPA believes the final rule clarifies 

those situations that trigger more extensive site investigations and 

better coordinates the objectives of the revised corrective action 

requirements within a site-specific framework.
g. Corrective Action Plan (§ 280.66)

In the final rule, proposed § 280.64 has been renumbered as 

§ 280.66 and retitled as "Corrective Action Plan." This revised section 

responds to commenters' requests for clarification of the owners' and 

operators' responsibilities for submitting corrective action plans 

(CAPs) and of the implementing agencies responsibility to request, 

review, and approve a CAP. Subtitle I of RCRA directs the Agency to 

promulgate corrective action regulations applicable to owners and 

operators of UST systems. The corrective action plan approval process, 

however, integrates the responsibility of owners and operators to 

ameliorate the adverse effects of UST releases with the responsibility 

of implementing agencies to determine how they will carry out their 

established public health policies. EPA's role is to: (1) establish 

the responsibility of owners and operators to achieve adequate 

protection of human health, and (2) establish a baseline framework for 

evaluating and approving corrective action plans.

Several commenters requested clarification of the owners' 

and operators' responsibilities for corrective action beyond immediate 

abatement steps and removal of free product. In response, § 280.66(a) 

of the final rule has been revised to clarify that owners and operators 

are responsible for submitting, when requested by the implementing 

agency, a corrective action plan that provides for adequate protection 

of human health and the environment. Section 280.66(b) of the final 

rule sets forth the factors that implementing agencies must consider 

when approving a corrective action plan. Consequently, this section 

also serves to inform owners and operators of the minimum elements 

required in the plans they submit.

Some commenters suggested the Agency establish explicit 

criteria that implementing agencies could use to determine whether a CAP 

is needed and to evaluate CAPs after they are submitted. As described 

in the preceding sections, EPA has revised several parts of the proposed 

rule to clarify the objectives of each step of the corrective action 

process. Owners and operators are responsible for carrying out and 

reporting these actions, thus providing the implementing agency with a 

good basis for determining the necessity for additional cleanup.

EPA believes it would be difficult and unproductive to 

incorporate more explicit evaluation criteria in today's rule. As 

described earlier in this preamble, EPA received wide support for the 

proposed site-specific corrective action goals and has retained this 

approach in the final rule. Implementing agencies, however, may choose 

to develop their own site-specific corrective action goals, or they may 

base cleanup goals on statewide numerical standards or aquifer 

characteristics. Rather than develop criteria that may conflict with a 

state or local agency's preferred method, EPA has chosen to identify in 

the rule those factors that are generally necessary for carrying out 

corrective actions regardless of the chosen method for setting precise 

cleanup goals. For example, these factors include the persistence of 

the released substance and the hydrogeologic conditions at the site. 

EPA sees its role primarily as providing technical support for 

interpreting these factors in the context of site-specific application 
of corrective action technologies. In particular, EPA is developing 

technical information and supporting materials to assist implementing 

agencies in relating site assessment results to the feasibility of 

alternative technologies, and for evaluating how well these technologies 

are achieving cleanup at a site. In addition, EPA is beginning to 

develop methods to expedite exposure assessments. Other programs within 

EPA, such as the Office of Ground-water Protection, may also be called 

upon to provide support for evaluating ground-water resources.

The overall objective of longer term UST corrective actions 

is to adequately protect human health, safety, and the environment from 

contaminants remaining in soils or ground water after initial abatement 

measures and free product removal. The Agency prefers that this 

objective be achieved, where practicable, through reducing contaminant 

concentrations in soil or ground water to levels protective of health 

and the environment. In some situations, however, the Agency would 

require--under the standard in § 280.66(a)-- that human health be 

protected from exposure to contaminants through other appropriate 

measures, such as providing an alternative water supply.

EPA cannot project the outcome of its site-specific 

approach to all UST releases because the consideration accorded to some 

factors, such as aquifer resource value and its current and potential 

use, is largely left to state and local policy. If an UST release 

affects a public or private drinking water source, however, the owner 

and operator must expect that the state's health-based drinking water 

standards would apply to the cleanup. If the owner and operator cannot 

meet these standards through cleanup technologies, then they should 

expect that they will be required to provide an alternate source of 

drinking water or to provide treatment of the water to the people 

affected. Similarly, the owner and operator should expect that UST 

releases that threaten current or potential water supplies will come 

under close scrutiny by the implementing agency. In these cases, the 

corrective action requirements will likely be influenced by the mobility 

of the contaminants at the site and the estimated time and spatial 

extent over which the remaining contamination may pose a threat. At a 

minimum, approved CAPs would likely include requirements for long-term 

monitoring, continued control of ground-water flow at the site, and 

notice of continuing hazard in the property deed.

The final rule retains the implementing agency's authority 

to require submission of a CAP based on information received from early 

corrective action measures. (EPA expects, for example, that 

implementing agencies might choose this option for UST releases that are 

of great magnitude or in close proximity to drinking water resources.) 

Final § 280.66(a), however, has been revised to make clear that the 

implementing agency must first review the submitted material before 

requesting the submission of a CAP or additional information. This 

section also has been revised to enable owners and operators to submit a 

CAP for soil and ground-water cleanup based on their own initiative and 

assessment of the severity of the release. They need not wait for the 

implementing agency to request a CAP.
Several commenters expressed concern that lengthy reviews 

by the implementing agency might slow the pace of UST cleanups, creating 

delays that could make implementing the final CAP more difficult, 

because of the spread of contamination while delays persist. Some 

commenters also suggested that owners and operators should be allowed--

after a specified length of time--to interpret inaction on the part of 

the implementing agency as approval of the CAP.

Given the number of releases that are expected to be 

detected in the near future, EPA acknowledges that there is potential 

for delayed cleanups under the proposed approach if implementing 

agencies are unable to review all the CAPs in a timely manner. The 

Agency concluded, however, that the alternatives suggested by commenters 

were inappropriate. To respond to this issue, however, § 280.66(d) has 

been added to allow owners and operators to begin cleanup of soil and 

dissolved contaminants in ground water without CAP approval provided 

they: (1) first notify the implementing agency of their intention to 

begin cleanup, (2) comply with modifications imposed by the implementing 

agency, including halting cleanup activities, and (3) incorporate these 

initial measures in the CAP to be reviewed and approved by the 

implementing agency.

EPA has added this provision with the goal of encouraging 

effective and expedited cleanup of soil and ground water. EPA 

emphasizes, however, that the implementing agencies remain the final 

arbiter for approving CAPs. Implementing agencies, therefore, can 

require the owner and operator to revise their CAPs and to modify the 

cleanup techniques in use at a site, including mitigating adverse 

consequences of cleanup activities. Since the implementing agency 

retains this authority, EPA expects that owners and operators who choose 

to initiate cleanup prior to approval of this CAP will select cleanup 

technologies that are widely used and recognized to be effective. EPA 

believes some cleanup techniques, such as extraction and treatment of 

petroleum vapors from soils, can be initiated with little risk of 

worsening contamination at the site. EPA also notes that states need 

not adopt the policy of owner- and operator-initiated cleanup for state 

program approval. Moreover, if states choose this option they can 

tailor its use to best meet their needs. For example, the implementing 

agency can identify specific cleanup technologies that are widely 

applicable without prior review or approval and those that always 

require explicit plan approval. Similarly, implementing agencies can 

decide to limit this option for use only at releases from certain USTs, 

such as petroleum USTs.

h. Reporting (Proposed § 280.65)

The reporting requirements in this section of the proposed 

rule have been consolidated with the requirements in § 280.51 of the 

final rule because they are part of the release confirmation process.

i. Public Participation (§ 280.67)
The proposed public participation rule required 

implementing agencies to provide opportunity for public review and 

comment on all CAPs and to consider these comments before approving 

CAPs.

Although commenters agreed that public participation is 

desirable, many commenters expressed concern that protracted public 

participation during the development of all CAPs could unnecessarily 

delay some UST cleanups. For example, cleanup efforts could be delayed 

while the development of a CAP was submitted to lengthy public review 

and deliberation. Also, mandating public participation for all CAPs 

could divert implementing agency resources from other cleanup activities 

such as oversight of ongoing cleanup operations.

EPA agrees with commenters who urged that implementing 

agencies strike a balance between the involvement of the public in 

corrective action decisions and the sometimes competing need to protect 

human health and the environment through quick and effective responses 

to an UST release. To acknowledge these sometimes conflicting 

objectives, the final rule for public participation establishes a 

flexible approach that ensures public access to available information on 

UST cleanups, although the public need not be involved, as a matter of 

routine, in all CAPs.

Implementing agencies continue, however, to have the 

responsibility and authority to notify the public about CAPs, to provide 

public access to the site and cleanup files, and to involve the public 

in meetings if sufficient interest is demonstrated. The final rule's 

public participation requirements for UST corrective action stress the 

need for adequate public notice, particularly to those parties who could 

be directly affected by the release and the planned corrective action. 

EPA expects that the public will be provided adequate opportunity to 

participate in and aid the UST cleanup process.

EPA does not agree with those commenters who opposed 

including any public participation requirements in the UST corrective 

action rule. In particular, EPA does not agree with the concerns raised 

that RCRA does not explicitly require public participation under 

Subtitle I. EPA believes that section 7004 of RCRA specifically 

mandates that all of the Agency's RCRA programs provide for the 

opportunity for public participation, including the RCRA Subtitle I 

program. This statutory mandate, combined with long-standing EPA 

policies to involve the public in the cleanup of contaminated sites, has 

prompted EPA's decision to keep the public participation requirements in 

Subpart F. In meeting this need, however, EPA has intended to require 

public notice and participation in UST corrective actions in a form that 

does not unnecessarily disrupt what state UST programs already require 

and provide.

The final rule requires public notification and public 

availability of information on CAPs. The implementing agency must 

notify the public about each confirmed release requiring a CAP. This 

notification requirement remains as proposed, although the rule no 

longer mandates implementing agencies to formally consider and respond 
to public comment before approving a CAP. The implementing agency must 

also provide public notice if implementation of the CAP does not achieve 

the established cleanup levels and the implementing agency is 

considering terminating the CAP. In most states, those affected by the 

release are often kept well informed through personal contacts with the 

state response staff. Today's requirements are not intended to change 

this practice of personal contact as one of the first points of public 

notice in the existing state UST programs. This method of notice has 

been added to the rule to make this clear. The list of public notice 

vehicles contained in the rule, however, is not intended to be 

exhaustive.

In addition to this notification requirement, the final 

rule requires the implementing agency to provide public access to site 

release information and decisions concerning the CAP. By providing 

public notification and access to information, implementing agncies 

ensure the opportunity for public participation in specific CAPs of 

interest to the affected sectors of the public. Because the Agency 

considers public notification and public access to information to be the 

key components of public participation for all CAPs, the final rule 

emphasizes the importance of these two requirements.

The implementing agency may hold a public meeting to 

consider public comments on a CAP if sufficient public interest is shown 

concerning a proposed CAP. EPA uses the phrase "public meeting" in the 

rule to emphasize that a formal public hearing is not required. EPA 

intends that a public forum be provided, in keeping with the state's 

administrative procedures, to inform the public and allow public comment 

on a CAP. The implementing agency will decide when public meetings are 

warranted on a case-by-case basis. EPA expects that large releases 

involving extensive corrective action will include correspondingly more 

extensive public participation because public understanding and 

acceptance is critical to the success of these CAPs.

In summary, the final rule emphasizes the implementing 

agency's responsibility to involve the public in a manner that best 

serves the environmental goals of the CAP.

G. Out-Of-Service UST Systems and Closures

1. Introduction

As discussed in the preamble to the proposed rule, the 

principal objective of the UST system closure requirements is to 

identify and contain existing contamination and to prevent future 

releases from UST systems no longer in service (52 FR 12757). Available

information suggested that UST systems improperly closed in the past 

have had undetected releases that later required corrective action. 

More of these systems may be found to have leaked and, in the future, 

require additional corrective action. Because a large number of 

existing UST systems are expected to close in the next 5 to 10 years, 

EPA believes that it is particularly important to require proper 
management procedures for out-of-service UST systems so that 

contamination due to improperly closed UST systems can be prevented from 

posing a threat of additional releases in the future and needed 

corrective action can be identified and taken. The comments on the 

proposal generally acknowledged that proper closure is an important 

aspect of sound UST management.

The closure procedures are covered in §§ 280.70 through 

280.74 of the final rule. Section 280.70 describes the requirements 

that must be complied with at all UST systems temporarily closed for 

less than 12 months. It also requires tanks that do not meet 

requirements for new or upgraded USTs, and that are taken out of service 

for 12 months or longer, to permanently close. Those USTs that do meet 

requirements for new or upgraded USTs can remain indefinitly out of 

service. Section 280.71 provides requirements for permanently closing 

or changing the service of an UST system, including identification of 

alternative methods for permanent closure and procedures for continuing 

the service life of an UST system when it is to be used for the storage 

of non-regulated substances. Section 280.72 describes the requirements 

for assessing the UST system excavation zone at closure. Section 280.73 

requires owners and operators to apply the permanent closure and site 

assessment requirements of the final rules to UST systems taken out of 

service before the effective date of the regulations, if so directed by 

the implementing agency. Section 280.74 lists the recordkeeping 

requirements. These proposed requirements, highlights of public 

comments on them, and the Agency's approach to the final UST system 

closure standards are discussed in more detail below.

2. Temporary Closure (§ 280.70)

To prevent owners and operators from improperly closing UST 

systems in the future, EPA proposed requirements in § 280.80(a)-(b) for 

tanks temporarily taken out of service for up to 24 months. These 

provisions only covered UST systems when a regulated substance was left 

in the tank and did not distinguish between unprotected tanks and 

protected tanks that met the requirements for new or upgraded UST 

systems.

The applicability of these requirements depends upon what 

constitutes temporary closure. Although a number of suggestions were 

received, generally commenters recommended defining temporarily closed 

based on both the use of the tank and how frequently regulated 

substances are typically moved through it. The failure to fill and/or 

take regulated substances from a tank on a regular basis, however, was 

not always considered to be a reasonable criterion for determining the 

tank was temporarily closed. Commenters cited several examples of 

infrequently used tanks where temporary closure was not appropriate, 

including emergency generator tanks and backup system tanks from which 

fuels were not typically dispensed for long periods of time.

The Agency believes that owners and operators will 

generally pay more attention to tanks that are used frequently than to 

those that are used only occasionally or are temporarily closed. Thus, 
the operation and maintenance procedures used to ensure the integrity of 

a tank and the effectiveness of release detection efforts instituted to 

identify leaks in and around a tank will be somewhat related to whether 

the tank is being actively used or not. Other possible factors in 

determining whether a tank is temporarily closed include adherence to 

the normal operation and maintenance procedures at the facility, the 

types and amounts of regulated substances stored at the facility, the 

likelihood that an undetected leak has occurred or may occur in the 

future, and the potential that the tank has become a receptacle for 

illegal dumping. The Agency does not intend that the emergency 

generator and backup fuel system tanks cited by commenters should be 

subject to automatic closure requirements merely because regulated 

substances are not moved through the tanks on a regular or frequent 

basis. If, however, the infrequent use of such a tank cannot be 

justified as part of its purpose and/or if the operation, maintenance, 

or release detection procedures associated with the tank are inadequate 

or inconsistent with the monitoring procedures required for operating 

tanks, the tank will be considered temporarily closed and, after 12 

months is up, subject to permanent closure requirements in accordance 

with § 280.70(c) of the final rule.

Several commenters pointed out that proposed § 280.80(a)-

(b), which covered temporary removal from use and temporary closure, 

only applied at tanks where the regulated substances were left in the 

tank. As a result, if the regulated substances were removed from the 

tank, the proposed rule appeared to exclude UST systems from the further 

application of the temporary closure provisions. EPA intended, however, 

that the closure requirements should be applicable to all UST systems 

that are taken out of service regardless of the quantity of regulated 

substance remaining in the tank. The Agency also believes that 

continuation of release detection is not necessary when the regulated 

substances and residual material have been adequately removed from the 

UST system. Therefore, the revisions to § 280.70(a) of the final rule 

subject tanks from which the regulated substances have been removed to 

the temporary closure provisions, but allows the owner or operator to 

discontinue release detection as long as the UST system is completely 

empty.

The final rule also does not contain a requirement to test 

the integrity of a temporarily closed tank before refilling, although 

several commenters suggested that such a test should be conducted before 

materials are reintroduced into an empty tank. EPA does not agree that 

such a requirement would provide significant benefits. There is no 

evidence that empty tanks are more vulnerable to structural failure than 

filled tanks. In addition, the Agency believes that the release 

detection standards set forth in the final rule are sufficient to 

rapidly detect any leaks or structural failures that may occur once the 

system is brought back into service.

Several commenters requested guidelines for determining 

when an adequate amount of the regulated substance has been removed from 

a tank to preclude the tank from the temporary closure requirements. In 

response to these comments, the final rule makes it clear all tanks that 

contained a regulated substance are subject to the temporary closure 
requirements regardless of the amount of material remaining in the tank 

when it is taken out of service. If the tank is empty, however, the 

owner and operator are not required to maintain release detection around 

the tank. The term "empty" is defined by incorporating the definition 

of "empty container" set forth in EPA regulations under Subtitle C of 

RCRA. This definition requires all materials to be removed that can be 

removed using commonly employed practices. No more than 2.5 centimeters 

(one inch) of residue or 0.3 percent by weight of the total capacity of 

the tank can remain in the system. EPA believes that this definition is 

adequate to ensure that the regulated substances remaining in the tank 

will not pose an unreasonable risk to human health and the environment 

if a release occurs during the temporary closure period.

To prevent owners and operators from indefinitely 

postponing permanent closure, EPA proposed in § 280.80(c) that all tanks 

be closed that had been out of service for more than 24 months. This 

period was considered a reasonable time for tank owners and operators to 

decide whether to permanently close or continue the use of a tank a 

tank. The period recommended to be allowed for temporary closure by 

commenters varied greatly. Commenters cited numerous cases where 

mandatory permanent closure after 24 months of temporary closure was 

neither appropriate nor justified. Most state regulatory authorities 

commenting on this proposal recommended a shorter temporary closure 

period.

One of the principal reasons cited by the commenters 

recommending extending the temporary closure period was that tanks in 

compliance with the appropriate corrosion protection and leak detection 

procedures do not pose a significant threat of future releases. The 

commenters also argued that the permanent closure of such tanks would 

create an economic hardship without providing any significant 

environmental benefit. EPA agrees with these commenters that UST 

systems that are adequately protected from corrosion and equipped with 

release detection systems pose a significantly lower threat to human 

health and the environment than unprotected tanks. This conclusion is 

also consistent with the comments submitted by state regulatory 

authorities that recommended a reduction of the closure period. Their 

recommendations are believed to stem primarily from the states' 

experience with unprotected, bare steel tanks and, consequently, 

strongly suggest that significant damage to the public health and the 

environment could occur if unprotected tanks are allowed to temporarily 

close and are left unattended for long periods of time. Therefore, 

§ 280.70(c) in the final rule reduces the allowed period for temporary 

closure of unprotected tanks from 24 months to 12 months. Any 

temporarily closed UST systems that do not comply with the performance 

standards for new tanks under § 280.20 or the upgrade requirements for 

existing tanks under § 280.21 must permanently close after the 12 month 

temporary closure period ends. However, UST systems that comply with 

the performance standards for new or upgraded UST systems set forth in 

the final rule may remain out of service indefinitely so long as they 

remain in compliance with the operation, maintenance, and release 

detection requirements of the final rule. Since spilling and 

overfilling associated with product transfer should not be a problem 

around tanks that have been temporarily closed, UST systems are not 
required to satisfy the spill and overfill requirements for new and 

upgraded systems in order to be excluded from the 12 month 

permanent/closure provisions in the final rule.

Many commenters also believed that owners and operators 

should have a mechanism for seeking and obtaining an extension of the 

temporary closure period (to avoid the permanent closure requirements) 

on a case-by-case basis. These comments pointed out that the automatic 

permanent closure of certain types of tanks was not appropriate after 12 

or 24 months (for example, where nearby road construction has 

temporarily closed the business using the tanks). In response to these 

comments, a provision has been incorporated allowing the implementing 

agency to approve an extension of the temporary closure period to 

address situations where permanent closure of an unprotected UST system 

is not appropriate after 12 months. To ensure that the variance process 

is not used to postpone corrective action activities, however, the owner 

or operator must complete a site assessment before the extension can be 

applied for.

3. Permanent Closure (§ 280.71)

The proposed rule required the owner or operator of an UST 

to notify the implementing agency and assess the excavation zone at 

least 30 days before permanent closure. Several of the commenters 

argued that completion of the site assessment at least 30 days prior to 

permanent closure was not always appropriate, for example, in cases 

where a tank is to be closed by removal or when closure is part of a 

corrective action. In response to these valid comments, § 280.71(a) of 

the final rule has been revised to allow more flexibility by requiring 

the owner or operator to conduct an excavation zone assessment after 

notifying the implementing agency but before completion of permanent 

closure. The final requirements continue to require notification at 

least 30 days before completion of premanent closure. To avoid any 

potential conflict between the notification requirements of this section 

and the response requirements under the corrective action provisions, 

closures initiated as a result of corrective actions under Subpart F are 

not subject to the notification requirements in § 280.71(a) because the 

implementing agency will have already been notified as part of the 

corrective action activities.

The methods for permanent closure were proposed in 

§ 280.80(f) and the revised methods are set forth in § 280.71(b) in the 

final rule. Emptying the tank by removal or filling with an inert solid 

material was a prerequisite for permanent closure under the proposed 

rule. The term "empty," however, was not defined in the proposed rule. 

In response to those commenters who argued that the amount of residual 

materials remaining in the tank system must be defined in order to 

minimize any future threat to human health or the environment, the final 

rule requires the tank to be "emptied and cleaned by removing all 

liquids and accumulated sludges." In accordance with EPA's effort to 

build upon accepted industry consensus codes, a note following final 

§ 280.71(c) identifies API 1604 and API 1631 as guidance on cleaning and 

closure procedures that may be used to comply with these requirements. 
EPA believes that following these codes concerning the removal of 

regulated substances and cleaning of tanks before permanent closure will 

ensure human health and the environment are protected. These codes also 

address the concerns expressed by a number of commenters regarding the 

disposal and reuse of tanks that have been removed from the ground. 

Although not mandated in the final rules, adherence to the guidance in 

these codes concerning these activities will ensure the safe handling of 

tanks and will minimize the risk of releases during closure.

The note following § 280.71(c) also contains a reference to 

the criteria issued by the National Institute for Occupational Safety 

and Health. These criteria provide guidance concerning the prevention 

of deaths and injuries to workers involved in the assessment, 

decontamination, and cleanup of spills and leaks around underground 

storage tanks. EPA suggests this code is particularly important to 

consider in the closure of hazardous substance tanks.

The final rule continues to allow owners and operators to 

permanently close tanks by either removing the tank from the ground or 

filling the tank with an inert solid material. Several commenters 

recommended that the rule require removal except when the tank is 

located under or immediately adjacent to other structures. Their 

concerns focused upon the potential for releases of residual materials 

remaining in a tank after it is filled with inert fill and left in 

place. EPA believes, however, that the final requirement concerning the 

removal of all liquids and accumulated sludges from the tank (required 

by § 280.71(b)) and use of the procedures outlined in API 1604 and API 

1631 will adequately prevent the future release of residual material 

after a tank is filled. Therefore, the final rule allows either method 

of permanent closure.

Several commenters recommended further clarification of the 

meaning of "inert solid material." The Agency believes that permanent 

closure in-place will adequately minimize the likelihood of future 

releases only if the inert fill material specifications and fill 

procedures used at closure are adequate to prevent the tank from 

surfacing after closure, will support the structural integrity of the 

tank as it deteriorates over time (to avoid cave-ins), and will 

completely seal the tank and associated piping from future use as a tank 

system. However, the Agency has decided to not specify in detail the 

materials for filling a tank because of the numerous choices available 

and the special considerations and problems inherent in each. Sand or 

concrete, for example, may restrict future construction activities on 

the site, or may complicate future removal and corrective action 

activities around the tank. EPA believes that such decisions should be 

left to the owner and operator to make on a site-specific basis.

EPA also agrees with the commenters who argued that the 

permanent closure requirements set forth in the proposed rule precluded 

the reuse of UST systems for unregulated substances. As a result, sound 

tanks could be forceably discarded even though this would serve no 

environmental purpose. Therefore, final § 280.71(c) gives owners or 

operators a third method of closing an UST system. This method allows 

the owner or operator to complete a change-in-service, which will allow 
the tank to be used to store non-regulated substances. To complete a 

change-in-service and avoid the other requirements under permanent 

closure, the implementing agency must be notified at least 30 days 

before the change-in-service is completed, and the tank must be cleaned 

and emptied by removing all liquids and accumulated sludges. In 

addition, the owner and operator must assess the site in accordance with 

§ 280.72.

4. Assessing the Site at Closure (§ 280.72)

The requirements for assessing the excavation zone around 

an UST system were proposed in § 280.80(d). Several assessment methods 

were listed for satisfying these requirements, including the use of 

external monitoring release detection methods allowed under § 280.41. 

Several commenters questioned the applicability of one or more of these 

methods in certain site-specific situations. Some commenters suggested 

that other equally effective, methods may be appropriate, including 

internal release detection monitoring. It was also suggested that the 

nature and extent of the excavation zone assessment should take into 

consideration various site-specific factors, many of which focused upon 

whether the tank is closed by removal or by closure in place.

The final rule, as set forth in § 280.72, specifies minimum 

requirements necessary to adequately characterize the presence of 

contamination where it is most likely to be present at the UST site. 

All of the methods listed in the proposed rule have been deleted except 

the use of external monitoring release detection methods, which continue 

to be allowed if they are operated in accordance with the final § 280.43 

requirements at the time of closure. Some of the other methods 

suggested by commenters, such as internal release detection monitoring, 

were not incorporated into the final rule because they do not monitor 

the condition of the environment outside the tank. EPA remains 

convinced that this is an important last step before permanent closure 

is complete to ensure prior releases are not missed or ignored at 

closure like they have been in the past.

Minimum assessment standards have been set forth in the 

final rule to coincide with the requirements set forth in Subparts E and 

F. These standards are designed to ensure that assessment information 

is representative of the site's condition and is obtained before 

closure. In order to be representative, the measurement methodology 

selected by the owner or operator must take into consideration factors 

such as the nature of the stored substance, type of backfill used around 

the tank, and the depth to ground water. Any other factors must be 

considered that may be appropriate for identifying the presence and 

source of contamination from the UST system. For example, soil gas 

sampling could be used if the regulated substance contains compounds 

that are highly volatile and if the local geology and hydrology do not 

significantly restrict the movement of the volatilized organic species. 

However, if the regulated substance consists primarily of heavier 

hydrocarbons and, as a result, the concentration of vapors in the soil 

is expected to be very low, soil sampling may be needed to provide the 

necessary representative analytical results.
The site assessment methodology used by the owner and 

operator must also consider the method of closure. The two allowed tank 

closure methods may be treated differently because tanks that are 

removed from the ground enable the bottom of the excavation to be 

visually inspected. A visual inspection of the tank and excavation zone 

should provide sufficient information for determining if and where the 

substances stored in the tank have leaked into the subsurface soil. 

Using this information, a variety of sampling methods may be adequate to 

make an initial determination of the presence of contamination and the 

need for corrective action.

On the other hand, the presence and size of leaks from 

tanks that are closed in place cannot be visually determined and, 

consequently, a more comprehensive assessment is necessary. Therefore, 

several measurement methods may be required to determine if 

contamination is present around the tank. For example, soil gas samples 

may be used to help identify where soil samples should be taken. EPA 

believes that these changes will give the implementing agency greater 

flexibility to consider a variety of site-specific factors in defining 

the nature and extent of an assessment. For example, although EPA 

believes that samples taken below an UST system will generally provide 

the most representative results, the final rule would allow samples to 

be taken at any depth or location. However, a state inspection may 

determine that soil samples taken from the backfill surrounding a tank 

or soil gas samples taken at depths where significant volatilization has 

occurred may not be representative and additional testing could be

required.

The proposed rule in § 280.80(e) required the owner and 

operator to comply with the corrective action requirements if a release 

was discovered as a result of the activities conducted under any of the 

closure provisions or by any other manner. As a result of comments that 

emphasized the interrelationship between the corrective action 

provisions and the closure requirements, the Agency believes that the 

criteria for initiating corrective action during closure activities 

should be the same as the criteria for initiating corrective action at 

any other time during the operational life of an UST system. The final 

rule sets forth these criteria in § 280.72(b).

5. Applicability to Previously Closed UST Systems (§ 280.73)

To address contamination threats expected to result from 

past closure practices, EPA proposed in § 280.80(d) that UST systems not 

properly closed in accordance with recommended industry practices before 

the effective date of the final regulation be revisited and properly 

closed. The closure activities were to include a site assessment of the 

UST system, and notification to the implementing agency. In addition; 

EPA proposed in this subsection to exept tanks that were previously 

closed in accordance with one of the existing industry consensus codes 

from these sites assessment requirements. The Agency specifically 

requested comments on these previsions in the proposal.
EPA proposed to apply the closure rules retroactively, 

recognizing that significant manpower and cost could be required to 

locate all previously abandoned tanks and to conduct site assessments. 

To reduce this burden and focus only upon abandoned tanks that possed 

the greatest potential of leaking in the future, the proposed provisions 

were limited to tanks that had not been properly closed pursuant to one 

of the industry consensus codes in existence at the time. Those 

consensus codes were believed to require only removal of the product 

stored in the tank.

Upon review of numerous public comments received on this 

approach, it appears that the procedures used to close most abandoned 

tanks have not been well documented in the past, making it difficult to 

determine what constituted compliance with this requirement and whether 

a tanks was properly closed. Moreover, several commenters argued that 

previous industry consensus codes were not designed to ensure 

containment of the material in the abandoned tank and may have actually 

facilitiated early releases due to the practice of punching holes in the 

bottom of the tank. Thus, the commenters suggested that tank systems 

closed by using practices considered state-of-the-art at the time were 

just as likely to leak as those that were improperly closed. It was 

also noted by severl commenters that the retroactive application of the 

closure provisions and imposition of site assessment requirements upon 

owners and operators of abandonned tanks would be costly to implement 

and would require the commitment of significant resources by the 

implementing agencies to track down and enforce.

EPA now believes that many of the concerns raised by 

commenters are probably well founded if the requirements were applied to 

all USTs closed before the effective date of the regulations. Such a 

"broad brush" approach would be very difficult, if not impossible, to 

enforce because of significant problems in locating the large number of 

tanks abandoned in the past, if not impossible, to enforce because of 

significant problems in locating the large number of tanks abandoned in 

the past, in identifying previous owners and operators, and in properly 

apportioning responsibility for the site assessment and closure 

activities. As noted earlier, the lack of documentation would also make 

it difficult for the implementing agencies to determine if a tank had 

been "properly closed."

EPA continues to believe, however, that a number of 

previously abandoned UST systems still contain regulated substances or 

may pose a threat to human health and the environment. As discussed in 

the preamble of the April 17 proposal, state UST program incident 

reports examined by EPA revealed approximately 300 releases reported 

between 1970 and 1984 that implicated abandoned UST systems. In 

addition, EPA expects more releases from the numerous operating USTs 

closed before the effective date of the notification requirements 

(May 8, 1986) and before the effective date of today's regulations. 

Because there is a reasonable probability that releases from such tanks 

may pose a threat to human health and the environment, the application 

of the closure provisions to these tanks, and in particular the site 

assessment requirements, may be necessary and appropriate.
EPA now believes that for tanks closed or abandoned before 

the effective date of today's regulations, the closure provisions should 

only be applied selectively under the discretionary authority of the 

implementing agency. These agencies are in the best position to 

identify abandoned tanks that may have been improperly closed, and to 

gauge the nature and extent of the threat posed by those tanks. They 

are also better able to identify the responsible owners and define the 

appropriate site assessment techniques. This approach is intended to 

enable the implementing agencies to effectively allocate their resources 

and only focus upon abandoned tanks that are suspected of posing 

potentially significant problems. This revised approach also reduces 

the unnecessary burden upon owners and operators of the discovered 

abandoned tanks by eliminating the requirement for them to revisit and 

conduct a site assessment at all tanks that have been previously closed, 

and removes the uncertainty associated with the "improper closure" 

standard.

Therefore, the final rule deletes the proposed requirement 

to conduct site assessments at all tanks improperly closed before the 

effective date of the final regulations. The final rule, however, 

requires owners and operators of abandoned tanks to comply with the 

closure provisions if so directed by the implementing agency when it 

determines there is a reasonable probability that the tank poses a 

potential threat to human health and the environment either now or in 

the future.

6. Closure Records (§ 280.74)

The recordkeeping requirements associated with closure were 

set forth in § 280.80(g) of the proposed rule. These requirements have 

been reorganized in the final rule in § 280.74 but have not been 

significantly changed. The principal change was the elimination of the 

reference to § 280.43 concerning the maintenance of release detection 

records. Because these requirements are in § 280.70(a) of the final 

rule through the reference to Subpart D, and are thereby made applicable 

to all out-of-service and closed UST systems, repetition of the 

reference is not considered necessary.

H. Analysis of Other Significant Comments

1. Reliance on Codes Developed by Nationally Recognized Organizations

As described in the preamble to the proposed rule (52 FR 

12696), the regulations required that all UST systems be designed, 

constructed, and protected from corrosion in accordance with a code of 

practice developed by a nationally recognized association or independent 

testing laboratory. In today's final regulations, the Agency has also 

included the use of industry codes for other technical sections of the 

rule (such as upgrading and repair of existing USTs). The Agency has 

noted throughout today's final technical regulations specific codes of 

practice that have or may be developed.
EPA did not receive any comments that were against or 

critical of the use of industry codes. One commenter did express the 

need for public input during the development of federal technical 

regulations. The Agency agrees that public participation is necessary 

for the development of sound industry codes and practices. In fact, the 

Agency wants to expand the use of and reliance on industry codes in 

order to provide a means for improving existing or methods or developing 

alternative methods of UST system management. EPA does not intend to 

adopt inadequate codes but wants to provide a flexible approach to 

codemaking by relying on nationally recognized organizations to develop 

new and improved codes and practices through a public process.

EPA is today clarifying this issue to alleviate any future 

misunderstandings. EPA interprets a "nationally recognized 

organization" to mean a technical or professional organization that has 

issued standards formed by the consensus of its members. The 

organization should ensure consideration of all relevant viewpoints and 

interests, including those of consumers and future or existing and 

potential industry participants, and the resulting standards should be 

widely accepted and technically sound. Thus, any code developed by an 

organization should be based upon a broad range of technical 

information, and performance crtieria should be central elements of the 

resulting standards. EPA believes that the following organizations, 

which have codes and standards referenced in today's regulations, are 

examples of "nationally recognized organizations":

American Petroleum Institute (API)

Association of Composite Tanks (ACT)

National Association of Corrosion Engineers (NACE)

National Fire Protection Association (NFPA)

National Leak Prevention Association (NLPA)

Petroleum Equipment Institute (PEI)

Steel Tank Institute (STI)

Underwriters Laboratory (UL)

Other similar organizations may also be considered 

"nationally recognized."
The final rule does not require the use of a particular 

issue of any code. The consensus codes are frequently revised and 

updated. The Agency believes that requiring the use of "the most recent 

edition" would cause undue confusion in the regulated community. For 

example, a facility may be installed in accordance with codes that are 

current at the time but may not have the equipment that meets the codes 

that are current 10 years later. EPA has concluded that the industry 

codes that are in effect at the date of publication of the final rule 

are protective of human health and the environment. The use of future 

editions of the codes in place of the editions that are now in effect is 

not required, but is encouraged as the updated codes will probably 

provide for newer, more effective technologies and practices. The use 

of past codes that have been replaced by new editions by the effective 

date of this rule is not allowed because some past recommended industry 

practices were not fully protective of human health and the environment.

The Office of Management and Budget has discussed 

regulatory codes and standards (OMB Circular A119, dated October 26, 

1982). OMB encourages the reliance on voluntary standards, commonly 

referred to as industry standards or consensus codes. The developers of 

such codes are called voluntary standards bodies, and are defined to by 

OMB to include private sector, domestic, or multinational organizations-

-such as nonprofit organizations; industry associations, professional 

and technical societies, institutions, or groups; and recognized testing 

laboratories--that plan, develop, establish, or coordinate voluntary 

standards. EPA interpretation of the phrase "nationally recognized 

organization" is intended to encourage the development and use of 

voluntary standards.

2. Additional Decisionmaking Authority for Implementing Agencies

As discussed elsewhere in today's FEDERAL REGISTER, EPA is 

promulgating requirements (in Part 281) for judging the stringency of 

state programs to be approved to operate in lieu of "the federal 

program." Under Section 9004 of RCRA, the state program must contain 

specific program elements that are no less stringent that the 

corresponding federal technical requirements. Instead of requiring a 

detailed line-by-line review and comparison of state requirements to 

federal technical requirements, EPA is today finalizing an approach to 

program approval that will compare state programs to the attainment of 

several general federal objectives that underlie the specific technical 

requirements provided in Part 280.

In support of this approach, on December 23, 1987, EPA 

proposed to include additional language in the technical requirements 

that was intended to ensure this approval process is flexibly 

implemented (52 FR 48647). In order to establish the federal objective 

for each program element, EPA requested comment on the addition of 

specific language into several sections of the technical standards that 

would clarify the Agency's intent to allow state implementing agencies 

to substitute their own procedural and administrative requirements for 

those set forth in the federal requirements. Such administrative 
requirements, while essential for direct implementation of the federal 

program, do not represent the only possible approach for protection of 

human health and the environment, and thus are not part of the federal 

objectives for defining what requirements must be "no less stringent" 

under section 9004 of RCRA.

Today's final technical standards include several of these 

wording changes proposed on December 23, 1987. A list of the specific 

sections and the changes that have been made in the final rules are 

provided in Table 2.

[INSERT TABLE 2 HERE]

In general, the Agency decided to include this additional 

language in the final technical requirements to ensure that different 

state procedural and administrative approaches could be judged no less 

stringent than the corresponding federal program. As discussed in more 

detail elsewhere in today's FEDERAL REGISTER, EPA has concluded that 

different state procedural and administrative requirements can be used 

and still achieve the underlying performance objective being established 

today for each program element. It is the Agency's intent to allow the 

states a significant amount of discretion in this matter, as long as 

they can demonstrate that overall program performance in each program 

element will not be adversely impacted by their use of differing 

administrative practices and procedures.

Many commenters were in favor of this more flexible 

approach to state program approval and most recommended the additional 

language be provided in the final technical rules to ensure a line-byline review is avoided. Other commenters exposed concern that 

additional language in the technical rules would encourage states to 

ignore the federal model. Finally, one commenter opposed the flexible 

approach and stressed the Agency should "hold the line" in maintaining 

that states adhere to national regulatory decisions, even if only in 

procedural matters.

EPA disagrees with those commenters who opposed the 

addition of implementing agency administrative discretion in the 

technical requirements. They appeared to want to hold states to lineby-line comparisons to the federal program as the preferred way to 

determine if they are no less stringent. Thus, they were generally 

opposed to the use of federal objectives for purposes of state program 

approval, as much as to the addition of greater discretion in the 

technical requirements that would ensure this approach could be 

implemented.

As is discussed in the preamble to the state program 

approval regulation elsewhere in today's FEDERAL REGISTER, EPA has 

adopted the federal objectives approach to assessing states programs 

programs for purposes of state program approval. Thus, the final 

technical standards rule also includes the proposed language providing 

additional authority to implementing agencies with respect to certain 

procedural or administrative requirements.
V. RELATIONSHIP TO OTHER ASPECTS OF THE UST SYSTEM PROGRAM

A. Interim Prohibition

Section 9003(g) of RCRA Subtitle I sets forth requirements 

for tank systems installed between May 7, 1985, and 90 days after 

today's promulgation of final new tank performance standards. During 

this period, UST may be installed unless it is corrosion protected, made 

of noncorrodible materials, or otherwise designed and constructed to 

prevent releases during the operating life of the facility due to 

corrosion or structural failure. The tank material(s) of construction 

must also be compatible with the substance(s) to be stored.

The final standards for new tank systems in today's rule 

(as discussed in section IV. of this preamble) are designed to replace 

the Interim Prohibition requirements. These final performance standards 

address design, construction, installation, release detection, and 

compatibility for new tank installations. The Interim Prohibition will, 

however, remain in effect by regulation for those tanks that have been 

deferred from coverage under the technical standards in Subpart A (e.g., 

some sumps, and field-constructed bulk tanks).

B. Notification

On November 8, 1985, EPA published the Final Rule on 

Notification Requirements for Owners of Underground Storage Tanks (50 FR 

46602). A form to be used for the required notification was included as 

part of the rulemaking.

The UST rules and standards for new tanks promulgated today 

are not intended to affect these established notification requirements 

except to add to the information required to be submitted with the 

notification requirements (see section IV.B.). These existing 

requirements have been recodified into § 280.22 of today's final rule. 

Owners of existing UST systems were required to notify their designated 

state agencies by May 8, 1986. Owners of new or replacement UST systems 

must notify their designated state agencies within 30 days of bringing 

the tank into use by submission of the November 8, 1985, federal form, 

or an approved alternate state notification form.

Section 9002(a)(6) of RCRA requires that, beginning 30 days 

after the issuance of today's final new tank performance standards, any 

person who sells a tank intended to be used in an UST system must advise 

the tank purchaser of the owner's notification requirements. This 

requirement is effective 30 days after publication of the new tank 

performance standards that are being promulgated today. This 

requirement is codified in § 280.22(e) of today's rule.
C. Leaking Underground Storage Tank Trust Fund

Amendments to Subtitle I of RCRA enacted as part of the 

Superfund Amendments and Reauthorization Act of 1986 (SARA) provide for 

a Leaking Underground Storage Tank Trust Fund. The amendments (Section 

9003 (h)) provide funds for cleanup of petroleum spills from UST systems 

and give EPA, and states that enter into a cooperative agreement with 

EPA, the authority to respond to releases of petroleum from UST systems. 

Almost all of the states have entered into these agreements with EPA 

and are now responding to petroleum releases from UST systems using 

Trust Fund revenues. These amendments to RCRA were necessary because no 

other federal environmental program includes specific authority for 

response to releases of petroleum from UST systems, although releases of 

petroleum affecting navigable waters can be responded to under section 

311 of the Clean Water Act.

Section 9003(h) provides that the Administrator may issue 

an order requiring corrective action prior to the promulgation of 

today's final corrective action regulations under Subtitle I. With the 

promulgation of today's requirements, the Administrator may use this 

same order authority, as well as the enforcement authority of section 

9006, to require owners or operators to undertake corrective action.

The Leaking Underground Storage Tank Trust Fund is being 

financed by taxes on motor fuels to pay for response costs in a limited 

set of circumstances. Until the effective date of today's final 

technical standards (90 days after publication of today's rule), the 

Administrator, or states under cooperative agreements, may use the Fund 

to pay for a particular corrective action whenever the action is 

necessary to protect human health and the environment. After that date, 

the statute provides for the use of the Fund primarily where the 

financial resources of the owners or operators are not sufficient to pay 

for the costs of corrective action, or if the owner or operator is 

otherwise unidentifiable, unwilling, or incapable of carrying out 

corrective action properly. In some cases, an identifiable and solvent 

owner or operator may be in compliance with all UST financial 

responsiblity requirements (to be discussed in a later FEDERAL REGISTER 

Notice) but lack financial resources to pay the entire cost of a 

response. In those cases, the Administrator or a state with a 

cooperative agreement is authorized to use the Fund to pay the costs 

that exceed the level of financial responsibility required of the owner 

and operator by the financial responsibility regulations.

If the owner and operator has failed to maintain the 

required level of financial responsibility, the Trust Fund may not be 

used, unless: (1) there is no solvent owner or operator; (2) there is 

an imminent and substantial threat to human health or the environment; 

or (3) there is a need to take corrective action outside the facility 

including the provision of alternative water supplies or relocation of 

residents.

Ninety days after publication of today's regulations, 

cleanups under the Trust Fund must be conducted in accordance with the 

corrective action requirements (Part 280 Subpart G).
D. Exempted Tank Studies

The regulations finalized today do not apply to certain 

tank systems that were exempted by statute under section 9001 of 

Subtitle I. Section 9009(d) and (e) of Subtitle I requires that EPA 

conduct a study of several of these systems and submit a report to 

Congress that includes recommendations as to whether these tanks should 

be regulated in the future. The Report to Congress will be issued later 

this year.

The Report to Congress will cover the following exempted 

tanks whose volume, including piping, is at least 10 percent 

belowground:

oFarm or residential tanks of 1,100 gallons or less capacity 

used for storing motor fuel for noncommerical purposes, and

oTanks used for storing heating oil for consumptive use on the 

premises where stored.

VI. RELATIONSHIP TO OTHER AGENCY PROGRAMS

This section discusses the relationship of today's final 

rules to certain other EPA regulatory programs. This discussion is for 

informational purposes only.

A. CERCLA

Section 105 of the Comprehensive Environmental Response, 

Compensation and Liability Act of 1980 (CERCLA, or Superfund) requires 

development of a list of national priorities among known sites with 

releases and threatened releases of hazardous substances, pollutants, 

and contaminants. The National Contingency Plan (40 CFR Part 300) 

regulates development of the National Priorities List (of sites with 

releases) as well as appropriate responses to the most serious releases. 

These regulations currently apply to releases of CERCLA-designated 

hazardous substances from underground storage tanks. CERCLA, however, 

does not apply to releases of petroleum from USTs or other sources.

Releases of hazardous substances from UST systems may 

require removal or remedial action responses by federal or state 

agencies, in accordance with 40 CFR Part 300. Some UST releases of 

hazardous substances are already included in the National Priorities 

List. When today's final rules become effective (within 90 days), 

owners and operators of UST systems that release hazardous substances 

will be subject to the corrective action provisions of the rules and, in 

selected cases, the removal or remedial action measures of 40 CFR Part 

300. It is the responsibility of the owner and operator of a hazardous 

substance UST system that releases hazardous substances to consult with 

the implementing agency to determine the applicability of CERCLA 
requirements and Subtitle I release response and corrective action 

requirements under Subpart F.

Under sections 102 and 103 of CERCLA, EPA has promulgated 

regulations (40 CFR Part 302) that identify hazardous substances and 

quantities of releases of these hazardous substances that must be 

reported to the National Response Center. Those regulations contain 

reporting requirements for releases equal to or in excess of the 

established reportable quantities (RQs). Under CERCLA, owners and 

operators of all kinds of storage, transportation, and disposal 

facilities containing hazardous substances must report releases to the 

National Response Center. Owners and operators of USTs with releases of 

hazardous substances that exceed the RQs set forth in 40 CFR Part 302 

will continue to be subject to those CERCLA reporting requirements.

Under today's rule, owners and operators that store 

hazardous substances in USTs are also required to report spill or 

overfill releases of these substances from USTs that exceed the RQ to 

the implementing agency within 24 hours, or another period specified by 

the implementing agency, and immediately begin containment and cleanup 

of the release. Owners and operators with spills or overfills of 

hazardous substances from USTs that are less than the reportable 

quantity will not be subject to the release reporting requirements 

although they will still be responsible to immediately contain and clean 

them up.

B. Hazardous Waste Tank Program

Under RCRA Subtitle C, EPA promulgated regulations for tank 

systems containing hazardous wastes (40 CFR Parts 264 and 265, July 14, 

1986) including underground tanks. The RCRA Subtitle I rules 

promulgated today apply to USTs containing "regulated substances." 

These regulated substances include petroleum and hazardous substances 

defined in section 101(14) of CERCLA, except for hazardous wastes 

regulated under Subtitle C. The exclusion of hazardous wastes from the 

definition of regulated substance avoids most of the overlapping 

jurisdiction of Subtitle I and Subtitle C. An overlap in jurisdiction 

does exist, however, for USTs containing petroleum wastes that are 

subject to the provisions of RCRA 3014. This overlap is discussed in 

the next section.

There is also a potential overlap in jurisdiction for USTs 

containing mixtures of petroleum and hazardous wastes. Today's final 

rules resolve this potential overlap by excluding such USTs from the 

universe of USTs subject to today's requirements. Unless otherwise 

exempted, such USTs would be subject to the requirements of Subtitle C. 

It is intended that today's rules regulate a different set of UST 

systems from those subject to regulation under Subtitle C.
C. Hazardous Waste Management Regulations

Section 3001 of the Resource Conservation and Recovery Act 

requires EPA to identify wastes that pose a hazard to human health and 

the environment if improperly managed. Under the regulatory program 

established by Subtitle C of RCRA, EPA has developed a process that 

identifies and publishes lists of hazardous wastes. Generators must 

determine whether their waste is on one of the lists in 40 CFR Part 261, 

Subpart D. If a waste is not listed as a hazardous waste, waste 

generators are required to determine if their waste is hazardous either 

by testing it to determine if it exhibits any "characteristics," based 

on knowledge about the physical and chemical composition of the waste. 

In the latter case, testing of the waste is not necessary if it is 

believed that it would not exhibit a hazardous waste characteristic. 

The waste generator, however, remains responsible for making the correct 

determinations concerning the characteristics of reactivity, 

corrosivity, ignitability, and extraction procedure (EP) toxicity, as 

specified in 40 CFR Part 261, Subpart C.

1. Hazardous Substances

Many hazardous substances regulated by the Subtitle I tank 

rules are currently on EPA's hazardous waste lists of commerical 

chemical products at 40 CFR Section 261.33(e) and (f). The products 

become hazardous wastes when discarded, including when spilled and then 

not cleaned up and used for their intended purpose. Soils, water, or 

other debris contaminated by these products are subject to regulation as 

hazardous waste (see 40 CFR 261.33(d)). A person removing such 

contaminated soil or debris during a cleanup is a hazardous waste 

generator, subject to Section 261.5 or Part 262.

2. Petroleum and Petroleum-based Substances

Petroleum-contaminated soils are not an EPA-listed 

hazardous waste. Based on its physical and chemical nature, petroleumcontaminated soil would not exhibit the hazardous characteristics of 

corrosivity or reactivity under 40 CFR 261. Some state UST programs 

have reported to the Agency that they require the use of the EPA tests 

for ignitability and EP toxicity to assist in making decisions about 

whether to manage th petroleum-contaminated soils on- or off-site. 

Other states have simply declared that the soils are not a hazardous 

waste and, therefore, do not require testing or management as a 

hazardous waste. Other states require management of petroleumcontaminated soils as a "special waste" that must receive special 

handling to control environmental and human health risks believed to be 

associated with the volatile organic chemical emissions known to come 

from such soils.

Although some states require the use of the EPA tests, 

petroleum-contaminated soils do not satisfy the EPA criteria for an 

ignitable hazardous waste. A substance is classified as a hazardous 
waste if it exhibits the characteristic of ignitability according to one 

of the following four criteria (40 CFR 261.21) as determined by using an 

ASTM or Administrator-approved testing procedures. The substance must 

be: (1) a liquid containing less than or equal to 24 percent alcohol 

having a flashpoint less than 140 F; (2) a nonliquid, but capable under 

standard temperature and pressure of causing fire through friction, 

absorption of moisture, or spontaneous chemical changes which burns so 

vigorously and persistently that it creates a hazard; (3) an ignitable 

compressed gas, as defined in 49 CFR 173.300; or (4) an oxidizer as 

defined in 40 CFR 173.151. Gasoline-contaminated soils do not satisfy 

criteria (1), (3), or (4). They do satisfy the nonliquid requirement of 

criterion (2); however, the Agency has concluded that they are very 

unlikely to ever be capable of causing fire by friction, absorption of 

moisture, or spontaneous chemical changes. These soils, therefore, 

should not be a hazardous waste under Subtitle C of RCRA due to 

ignitability.

Several states contacted by EPA reported that they have 

conducted thousands of EP toxicity tests on petroleum-contaminated soils 

and they have never exhibited the characteristic of EP toxicity at 

numerous sites nationwide where soils were contaminated by both leaded 

and unleaded gasolines. This result is expected because the extraction 

procedure is designed to identify individual wastes that are hazardous 

due to their potential to leach significant concentrations of eight 

specific metals, four insecticides, and two herbicides in a municipal 

landfill scenario. When subjected to the EP toxicity test, the only 

constituent of concern for soils contaminated by petroleum is lead. The 

extremely high adsorption coefficient of lead, however, indicates that 

such soils are unlikely to ever exhibit the characteristic of EP 

toxicity.

In summary, the evidence collected by or reported to the 

Agency to-date indicates it is very unlikely that petroleum-contaminated 

soils will be found to exhibit any of the characteristics of hazardous 

waste as currently defined by EPA regulations. However, EPA is also 

aware that there are potential threats that need to be considered in the 

management of petroleum-contaminated soils. For example, petroleumcontaminated soils (particularly motor fuels) can contribute significant 

amounts of volatile compounds to the air or be the source of dissolved 

contaminants (such as benzene) in ground-water resources. Today's final 

regulations leave the off-site management of these concerns to existing 

state and local requirements. EPA believes there are several ways to 

properly manage petroleum-contaminated soils that are not hazardous 

wastes, including the following approaches that are already being used 

in various states:

oDefine petroleum-contaminated soils as a non-hazardous waste 

that requires disposal into permitted solid waste 

facilities.

oDefine it as a special waste that requires special handling 

(such as land spreading, heat treating, or disposal in 

designated fill areas) that is tailored to remove the 
threats posed by the volatile constituents of the 

petroleum.

oDefine petroleum-contaminated soils as a hazardous waste that 

must be treated or disposed of under the hazardous waste 

standards.

EPA intends to study this technical issue further and 

provide more information to the public and the implementing agencies 

concerning alternative ways to manage petroleum-contaminated soils when 

they are managed on-site or removed off-site. This information may 

include, for example, a description of different test methods that could 

be used to characterize petroleum-contaminated soils in a more 

meaningful fashion than present methods. EPA is currently investigating 

techniques to measure and assess the condition of petroleum-contaminated 

soils, and handling and treatment alternatives that can be used to 

properly manage the potential risks they pose to human health and the 

environment.

Finally, EPA notes that under proposed revisions to the 

toxicity characteristic under the Agency's hazardous waste regulations 

(40 CFR 261.24), benzene and a number of other compounds would be added 

to those constituents that, when measured in waste leachate, will 

determine whether a waste exhibits a hazardous waste characteristic. 

(See 51 FR 21648; June 13, 1986.) When these rule revisions are issued 

in final form, a large amount of petroleum-contaminated soils that are 

currently considered nonhazardous may have to be managed as hazardous 

waste. For example, all petroleum-saturated soils may be characterized 

as a hazardous waste under the proposed revisions. EPA is unsure of the 

impacts of this proposed rule change at this time, and in fact recently 

requested additional public comments on the levels for benzene and other 

constituents. (See 53 FR 18024; May 19, 1988.) However, the public 

comment period is closed on this issue. The Agency will provide further 

guidance on this issue at a later date.

D. Used Oil Regulations

Underground tanks storing used oil (e.g., automobile and 

truck used crankcase oil) are under the jurisdiction of Subtitle I. 

Pursuant to section 9001(2)(B) of RCRA, underground tanks containing 

"petroleum, including crude oil or any fraction thereof which is liquid 

at standard conditions of temperature and pressure . . ." are within the 

scope of Subtitle I. Since used oil is primarily composed of petroleum, 

although it may contain contaminants due to use of the oil, it is 

subject to Subtitle I requirements. Owners and operators of UST systems 

containing used oil were required to notify designated state agencies of 

the presence of such tanks by May 8, 1986. Owners and operators of 

newly installed used oil UST systems have also been subject to the 

requirements of the Interim Prohibition, which has been in effect since 

May 8, 1985.

As discussed above, however, today's regulations exclude 

any tanks regulated under Subtitle C of RCRA. Under Subtitle C, EPA has 
the authority to regulate recycled oil, and to regulate used oil that is 

disposed of under Subtitle C if such oil is identified or listed as a 

hazardous waste. Under the authority of Subtitle C of RCRA, EPA 

proposed to list used oil as hazardous waste (50 FR 49269-49270, 

November 29, 1985) and has proposed standards for recycled oil (50 FR 

49250-49258, November 29, 1985). Since those publications in the 

FEDERAL REGISTER, several important decisions in terms of these proposed 

rulemakings have been made, namely:

(1) Storage of used oil (even when recycled) will be 

regulated, and

(2) Recycled oil will not be listed as a hazardous waste 

(51 FR 41900, November 19, 1986).

The storage of used oil, however, is not currently 

regulated as a hazardous waste under Subtitle C. Unless and until the 

Agency regulates the storage of used oil as a hazardous waste under 

Subtitle C, it will be subject to Subtitle I. Accordingly, the Agency 

is today including application of the technical requirements to used oil 

UST systems. This is discussed in further detail in section IV.A.

E. SPCC

Under section 311 of the Federal Water Pollution Control 

Act, EPA has promulgated regulations for the prevention of oil spills 

into navigable waters. These rules (40 CFR Part 112) known as the Spill 

Prevention Control and Countermeasure (SPCC) regulations are intended to 

prevent and contain releases of oil into surface waters which are 

navigable.

Comparatively few UST systems are subject to SPCC 

regulations. Only those tanks of greater than 42,000 gallons capacity 

that are located near navigable waters of the U.S. or adjoining 

shorelines may be affected. UST systems which, due to their location, 

could reasonably be expected to discharge oil into or upon navigable 

waters of the United States or adjoining shorelines and which have a 

storage capacity greater than 42,000 gallons are subject to both today's 

rules and the SPCC rules.

F. DOE High-Level Radioactive Waste Program

Under the Atomic Energy Act of 1954 (42 U.S.C. 2001 et 

seq.), the U.S. Department of Energy (DOE) has promulgated rules for the 

management of high-level radioactive waste resulting from atomic energy 

defense activity. DOE Orders 5480.1, 5480.2, and 5820.2 regulate the 

underground storage of these wastes, including corrective actions in the 

event of a release.

The UST rules include the storage of radioactive waste 

because any radionuclide is a "hazardous substance" under CERCLA and 

thus a regulated substance under Subtitle I. However, in view of the 
differences in high-level radioactive waste from other RCRA Subtitle I 

regulated substances and the much larger tanks storing this waste, EPA 

is today deferring regulatory action on these DOE radioactive waste 

facilities. Until a determination is made as to whether, and how, the 

UST rules should apply to DOE facilities storing high-level radioactive 

wastes, today's UST requirements, except corrective action and the 

Interim Prohibition requirements, do not apply to these facilities. 

More details are provided on this in section IV.A.

VII. ECONOMIC AND REGULATORY IMPACTS

Section VII.A. discusses the Regulatory Impact Analysis of 

the final rule required by Executive Order 12291. Section VII.B. 

discusses the analysis of the effects of the final rule on small 

businesses required by the Regulatory Flexibility Act. Section VII.C. 

addresses requirements under the Paperwork Reduction Act. (A full draft 

of the Regulatory Impact Analysis for the final rule is available as 

part of the background documents supporting this rulemaking.)

A. Regulatory Impact Analysis

1. Executive Order 12291

Executive Order 12291 (46 CFR 13193, February 19, 1981) 

requires regulatory agencies to conduct a Regulatory Impact Analysis 

(RIA) for any major rule. EPA has conducted an RIA to assess the 

regulatory impacts of the technical standards rule for USTs based on the 

guidelines contained in the Office of Management and Budget's "Interim 

Regulatory Impact Analysis Guidance" and EPA's "Guidelines for 

Performing Regulatory Impact Analysis." The objective of the analysis is 

to examine the anticipated costs, benefits, and impacts of the final 

rule rather than to select a regulatory option. Based on the results of 

the analysis, the Agency has concluded that the technical standards 

regulations being promulgated today represent a major rule that produces 

significant net benefits to society.

As described in today's preamble, these technical standards 

pertain to tank system design, construction, and installation, leak 

detection, recordkeeping, reporting, closure, and corrective action. 

For the proposed rule (52 FR 12761-12769), EPA conducted an RIA to 

compare several regulatory alternatives. Each of these alternatives is 

discussed in detail in the "Regulatory Impact Analysis for Proposed 

Technical Standards for Underground Storage Tanks" (April 1987). (This 

RIA for the proposed rule is contained in Appendix B of the RIA for the 

final rule.) The RIA for the final rule does not consider various 

options. Instead, it concentrates on the impacts of the provisions of 

the final rule (see sections III. and IV. of today's preamble for a full 

description of the requirements of the final rule.)

The final rule refines the proposed rule (April 17, 1987) 

by phasing in requirements for release detection over a period of 5 
years for existing tanks (based on the age of the tank) and by 

establishing more stringent requirements for pressurized piping. Most 

of the other requirements in the final rule pertaining to corrosion 

protection and release detection are the same as in the proposed rule.

2. Costs

Compliance with the rule's requirements for release 

detection, system inspections and upgrading, and corrective action will 

require large expenditures by most UST owners and operators. In 

addition, the large population of USTs means that the total costs for 

all USTs will be substantial from the standpoint of the economy as a 

whole.

Table 3, column 2, displays the costs of the final rule for 

the entire UST population, by category of costs. These cost estimates 

represent costs calculated using the UST Model, a model developed by the 

Agency to simulate the release and transport of petroleum products. 

These estimates assume a total of 1.7 million USTs and a total of 30 

years of costs after promulgation of the rule, discounted at a rate of 3 

percent annually. Based on EPA's analysis and assumptions, the 

estimated cost of the final rule is expected to be approximately $69 

billion over a period of 30 years, or $3.6 billion per year (discounted 

at a rate of 3 percent).

[INSERT TABLE 3 HERE.]

In order to evaluate the incremental costs of the final 

rule, EPA estimated the costs that would be incurred by UST owners and 

operators in the absence of any further regulations. These costs are 

presented in column 1 of Table 3 as base case cost. Subtracting the 

base case costs from the costs under the final rule yields the 

incremental cost of the final rule, shown by cost category in Table 3, 

column 3. This incremental cost is expected to be approximately $48 

billion over 30 years, or $2.5 billion on an annual basis (discounted at 

an annual rate of 3 percent). The administrative costs of implementing 

the final rule are not included in this analysis.

3. Benefits

The final rule's requirements for leak detection and 

prevention and corrective action will provide society with a variety of 

benefits. The benefits are defined as reductions in damages under the 

rule in comparison to the base case. Two kinds of damages are 

considered in the RIA: those that occur before a release is detected, 

such as contamination of private and public wells; and those that occur 

after a release is detected, such as contamination of soil and ground 

water.
The pre-detection damages are $2.1 billion under the final 

rule, and $4.8 billion in the base case. The incremental benefits of 

regulation resulting from this decrease in pre-detection damages are 

therefore $2.7 billion. The post-detection damages are estimated to be 

$52.8 billion under the base case, and negligible under the final rule. 

(Under the final rule, corrective actions must be performed as soon as 

a release is detected which accounts for this drastic reduction in postdetection costs.) The incremental benefits of regulation resulting from 

a decrease in post-detection damages are therefore $52.8 billion. The 

total incremental benefits of the rule, including the benefits from 

reduction in both pre- and post-detection damages, are $55.5 billion 

($2.7 billion due to reduction of pre-detection damages and $52.8 

billion due to reduction of post-detection damages). The yield in 

benefit for each UST is about $31,000.

EPA believes that, in addition to the benefits summarized 

above, many additional benefits of release detection and prevention 

cannot be expressed quantitatively or in purely monetary terms. 

Examples of these important benefits include the prevention of added 

risks to human health, the value of preventing damage to the ability of 

streams to support life, and the basic value of preventing contamination 

of ground-water resources whether or not they are currently being used.

In an attempt to provide some measure of these benefits, 

EPA has quantified the health benefits of the release detection, 

prevention, and corrective action portion of the final rule, but has 

expressed the benefits in terms of cancer cases avoided and the 

reduction in numbers of USTs posing cancer risks in excess of a

specified threshold (Table 4). Of the two scenarios shown in Table 4, 

one scenario assumes that people will not use water that smells or 

tastes badly. The other scenario assumes that people will use water 

whether it seems contaminated or not.

[INSERT TABLE 4 HERE.]

4. Cost Effectiveness of the Final Rule

!viia4a! A comparison of the incremental costs of the final rule to 

its incremental benefits is shown in Figure 6. The figure shows the 

incremental costs of the final rule to be $48.9 billion, which include 

repair, system upgrading and replacement, release detection, and 

corrective action for the entire population of 1.7 million USTs. In 

contrast, the incremental benefits of the rule are estimated to be $55.5 

billion. These benefits consist largely of reductions in damages 

occurring after releases are detected, but also include reductions in 

well and vapor damages and lost product occurring before the detection 

of releases. By subtracting costs from benefits, the net dollar

benefits of the final rule over the next 30 years are estimated to have 

a present value of $6.6 billion, or $4,000 per UST. In addition to the 

benefits measured in dollar terms, the rule also significantly reduces 

damages to human health and the environment.

[INSERT FIGURE 6 HERE.]
5. Economic Impacts on Existing Facilities

An economic impact analysis was performed for the general 

industry and retail marketing sectors having petroleum USTs and for 

firms having hazardous substance USTs. The results of this analysis 

indicate that firms in the retail motor fuel marketing sector would be 

most adversely affected, for several reasons: they have a greater 

number of small firms that are more vulnerable to significant regulatory

expenditures; regulatory expenditures in this sector are likely to be 

greater because motor fuel retail outlets generally have the greatest 

number of USTs per outlet; and firms in the retail motor fuel marketing 

sector do not have the option of closing their USTs and using 

alternative storage methods. The RIA reaches the following conclusions:

oBy year ten, 43 percent more small firms are projected to 

close under the final rule than in the base case.

oMost economic impacts of the final rule occur in the first 5 

years after its imposition.

oMost closures of existing outlets are caused by corrective 

action expenses.

oWere corrective action to be performed in the base case as 

well as under the final rule, the model predicts that a 

higher percentage of outlets would survive under the final 

rule than in the base case.

6. Integration of Technical Standards and Financial Responsibility 

Rules

EPA prepared separate RIAs for the proposed technical 

standards and financial responsibility rules in order to estimate the 

costs and economic impacts of each proposed rule. As many commenters 

pointed out, a major weakness of this approach was that the two RIAs 

could not easily be used to assess the combined impacts of the proposed

technical standards and financial responsibility rules to construct an 

"after regulation" picture of the regulated community. Commenters also 

noted that certain indirect costs that would be imposed on the regulated 

community were not included in either RIA. They explained that in order 

to buy insurance to satisfy the financial responsibility requirements, 

UST owners and operators would have to upgrade their USTs by installing 

release detection systems sooner than required by the technical 

standards rule.

In response to these comments, EPA has revised its approach 

in preparing the RIAs for the final rules, so that the two RIAs now 

perform the following functions:

oAccount for the indirect costs of having to upgrade tank 

systems sooner to procure financial assurance; and
oEstimate the combined costs and economic impacts of both sets 

of requirements.

The RIA for the financial responsibility rule assumes the 

technical standards rule in its base case in order to estimate its costs 

and economic impacts. The costs incurred in upgrading, replacing, 

retrofitting, and corrective action are attributed to the technical 

standards rule. Costs incurred to upgrade sooner than required by the 

technical standards rule in order to obtain financial assurance are 

attributed to the financial responsibility rule. By using the technical 

standards rule as the base case and computing the incremental costs of 

the financial responsibility rule, the overall costs to the regulated 

community can be estimated properly.

B. Regulatory Flexibility Act

Under the Regulatory Flexibility Act of 1980 (5 U.S.C. 601 

et seq.), agencies publishing a proposed or final rule must prepare and 

make available for comment a Regulatory Flexibility Analysis that 

describes the potential impact of the rule on small entities (i.e., 

small business, small organizations, and small government 

jurisdictions). The purpose of the Regulatory Flexibility Act is to 

ensure that regulations do not impose unnecessary costs or other burdens 

on such entities. As part of its RIA, EPA has examined the potential 

impact of today's rule on small entities and has concluded that the rule 

will have a significant impact on a substantial number of small 

entities, as described below:

1. Small Entities Potentially Affected by the Rule

The Agency divided the businesses potentially affected by 

the rule into three categories: firms engaged in retail motor fuel 

marketing (e.g., gasoline service stations), firms engaged in other 

businesses (general industry category), and local government entities. 

EPA focused the emphasis of the Regulatory Flexibility Analysis on the 

retail motor fuel marketing sector because (1) all firms in this sector 

must store their product in underground storage tanks; (2) about threequarters of all retail motor fuel outlets are owned or operated by small 

businesses; and (3) the data base for this sector is reasonably accurate 

and will capture the most severe small-business impacts likely to occur 

as a result of the rule.
a. Small Businesses in the Retail Motor Fuel Marketing Sector

For this Regulatory Flexibility Analysis, small businesses 

in the retail motor fuel marketing segment are defined as firms with 

less than $4.6 million in annual sales and include all firms with only 

one or two outlets. Firms with $4.6 million in sales will typically 

have approximately $500,000 in assets and a net worth of about $250,000. 

EPA estimates that in 1984, small businesses either owned or operated 

72 percent of the 193,000 retail motor fuel outlets in the United 

States.

To examine the rule's potential economic impact on small 

businesses, EPA estimated the rates at which existing firms in the 

retail motor fuel marketing sector would leave the industry with and 

without regulations. For the purposes of this analysis, EPA estimates 

that these outlets have historically tended to exit the industry at a 

rate of 3 to 4 percent per year. If releases occur at the level 

estimated by the RIA and no revenue increases are possible for small 

businesses, this rate would increase to 6.2 percent per year, assuming 

average corrective action costs.

b. Small Businesses in the General Industry Sector

An estimated 24 to 41 percent of all USTs in the general 

industry sector are owned by firms with less than $1 million in assets. 

A typical small firm in this segment was assumed to have $300,000 in 

assets and net profits of $21,000 a year. Overall, these firms 

represent about 12 percent of all UST-owning firms in the general 

industry sector.

The cost of corrective action for non-plume release (i.e., 

no ground-water contamination) would leave a small general industry firm 

in severe financial distress, and the cost of corrective action for a 

plume release (i.e., contamination of ground water) would lead to the 

failure of the firm. Replacing a tank would cause a small general 

industry firm a temporary financial hardship; however, this hardship 

would not seriously threaten the survival of the firm.

c. Small Local Government Entities

Local government entities of all sizes own USTs. In 1982, 

the typical municipality with a population less than 50,000 had general 

revenues of $1.7 million. The costs of replacing even a single UST 

would represent 2 percent of the revenue of such a municipality, a 

significant expenditure that would have to be taken into account when 

planning. A corrective action that required cleaning up a dispersed 

plume would represent more than 13 percent of the general revenues of 

such a community, a sum that would probably cause severe financial 

distress.

In 1982, of the 38,886 local governments classified as 

counties, municipalities, and townships, 37,581 (approximately 97 

percent) had populations of 50,000 or less. Almost all UST-owning local 
governments would, therefore, be subject to potentially substantial 

economic impacts under the technical standards rule if an UST release 

occurred.

C. Paperwork Reduction Act

The information collection requirements in this rule have 

been approved by the Office of Management and Budget (OMB) under the 

Paperwork Reduction Act, (44 USC 3501 et seq.) and have been assigned 

OMB Control Number 2050-0068. Reporting and recordkeeping burden on the 

public for this collection is estimated at 8,265,220 hours for the 

1,750,000 respondents, with an average of 4 hours per response. These 

burden estimates include all aspects of the collection effort and may 

include time for reviewing instructions, searching existing data 

sources, gathering and maintaining the data needed, and completing and 

reviewing the collection of information.

If you wish to submit comments regarding any aspect of this 

collection of information, including suggestions for reducing the 

burden, or if you would like to a copy of the information collection 

request (please reference ICR #1360), contact Rick Westlund, Information 

Policy Branch, PM-223, U.S. Environmental Protection Agency, 401 M 

Street, S.W., Washington, D.C. 20460 (202-382-2745); and Marcus Peacock, 

Office of Information and Regulatory Affairs, Office of Management and 

Budget, Washington, D.C. 20503.

VIII. LIST OF SUBJECTS IN 40 CFR PART 280

Administration practice and procedures, Confidential 

business information, Ground water, Hazardous materials, Reporting and 

recordkeeping requirements, Underground storage tanks, Water pollution 

control, Water supply.

 

Lee Thomas

Administrator