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53 FR 37082-37247 Friday, Sept. 23, 1988 40 CFR Parts 280 and 281, Underground Storage Tanks; Technical Requirements and State Program Approval; Final Rules--Preamble Section IV. Analysis of Today's Rule--B. UST Systems: Design, Construction, Installation, and Notification


IV. Analysis of Today's Rule

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)


B. 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 field-installed 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 site-specific 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 been 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 field-installed 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.

o Corrosion 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).

o Release 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.

o UST 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.

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