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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--G. Out-of-Service UST Systems and Closures


IV. Analysis of Today's Rule

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)


IV.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 indefinitely 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 permanent 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 exempt 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 posed 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 facilitated 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 several commenters that the retroactive application of the closure provisions and imposition of site assessment requirements upon owners and operators of abandoned 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.

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