OSWER 9360.8-38
MEMORANDUM
SUBJECT: Use of Alternative Secondary Containment Measures at Facilities
Regulated under the Oil Pollution Prevention Regulation (40 CFR Part
112)
FROM: Marianne Lament Horinko
Assistant Administrator
TO: Oil National Policy Managers, Regions 1-10
PURPOSE
This memorandum amends the guidance issued on April 29, 1992 (i.e., Use of
Alternative Secondary Containment Measures at Facilities Regulated under the Oil
Pollution Regulation (40 CFR Part 112), (OSWER 9360.8-37) concerning the potential
use of certain double-wall aboveground storage tanks (ASTs) for secondary
containment purposes. A copy is attached for your reference. This guidance also
clarifies when shop-built double-walled ASTs satisfy the applicable secondary
containment requirements in the Spill Prevention, Control, and Countermeasure (SPCC)
rule, found at 40 CFR part 112. We take this step because larger shop-built ASTs that
use the protective measures described in the 1992 guidance are generally protective of
the environment under certain circumstances.
BACKGROUND
On April 29, 1992, EPA issued guidance on how certain shop-built double-wall
ASTs may comply with the secondary containment requirements of §112.7(c). The
guidance discussed compliance with §112.7(c) only, and did not discuss compliance
with other applicable SPCC provisions. We said at the time that "there should be many
situations in which protection of navigable waters substantially equivalent to that
provided by the secondary containment systems listed in section 112.7(c) could be
provided by alternative AST systems that have capacities generally less than 12,000
gallons and are installed and operated with protective measures other than secondary
containment dikes."
DISCUSSION
SPCC secondary containment requirements. Section 112.7(c) requires that
the owner or operator:
"Provide appropriate containment and/or diversionary structures or equipment to
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OSWER 9360.8-38
prevent a discharge as described in §112.1 (b). The entire containment system,
including walls and floor, must be capable of containing oil and must be
constructed so that any discharge from a primary containment system, such as a
tank or pipe, will not escape the containment system before cleanup occurs. At a
minimum, you must use one of the following preventive systems or its equivalent:
(1) For onshore facilities:
(i) Dikes, berms or retaining walls sufficiently impervious to contain
oil;
(ii) Curbing;
(iii) Culverting, gutters or other drainage systems;
(iv) Weirs, booms or other barriers;
(v) Spill diversion ponds;
(vi) Retention ponds; or
(vii) Sorbent materials.
(2) For offshore facilities:
(i) Curbing, drip pans; or
(ii) Sumps and collection systems."
After nearly a decade of evaluation of the construction, performance, and use of certain
shop-built double-wall ASTs, we believe that they may serve as an "equivalent"
preventive system for purposes of §112.7(c).
In 1992, we recognized that a shop-built double-wall AST with a capacity
"generally less than 12,000 gallons" that was installed and operated with protective
measures other than a secondary containment dike might meet the secondary
containment requirements of §112.7(c). We described those protective measures as
"when the inner tank is an Underwriters' Laboratory-listed steel tank, the outer wall is
constructed in accordance with nationally accepted industry standards (e.g., those
codified by the American Petroleum Institute, the Steel Tank Institute, and the American
Concrete Institute), the tank has overfill prevention measures that include an overfill
alarm and an automatic flow restrictor or flow-shutoff, and all product transfers are
constantly monitored."
Today, after nearly a decade of experience in which we have seen the
construction, performance, and use of shop-built double-wall ASTs, we note a low
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OSWER 9360.8-38
occurrence of discharges from such tanks, including tanks with a capacity of 12,000
gallons or more. In some cases, such tanks provide secondary containment where
none existed before, or superior environmental protection to alternative containment
systems previously used. We believe that a 12,000 gallon limitation on the use of
certain shop-built double-wall ASTs is therefore no longer necessary, and believe that
shop-built double-wall ASTs that use the protective measures described in 1992
generally satisfy the secondary containment requirements found in §112.7(c).
Bulk storage secondary containment requirements (§112.8(c)(2));
inspection requirements (§112.8(c)(6)). For the same reasons outlined above, we
also believe that shop-fabricated double-wall AST, regardless of size, may generally
satisfy not only the secondary containment requirements of §112.7(c), but also the bulk
storage secondary containment requirements found at §112.8(c)(2). Section
112.8(c)(6) requires the owner or operator to conduct integrity testing on a regular
schedule and whenever he makes repairs. The owner or operator must also frequently
inspect the outside of the container for signs of deterioration, discharges, or
accumulation of oil inside diked areas. To comply with the requirement to frequently
inspect the outside of the tank, an owner or operator must inspect the inner wall and
interstitial spaces of a shop-built double-wall AST. We recommend the use of automatic
detection devices to detect discharges into the interstitial space. Owners or operators
should conduct this integrity testing and inspection in accordance with industry
standards, when practicable. One industry standard presently available is "SP001-00,
Standard for Inspection of In-Service Shop-Fabricated Aboveground Tanks for Storage
of Combustible and Flammable Liquids." Other applicable standards may be developed
in the future.
Other applicable SPCC requirements. While shop-fabricated double-wall
ASTs may satisfy the requirements of §112.7(c) and §112.8(c)(2), such tanks must also
continue to satisfy all other applicable SPCC requirements. For example, the facility
owner or operator must satisfy §112.7(h) requirements for tank car and tank truck
loading/unloading racks if he transfers oil in bulk to those tanks from highway vehicles
or railroad cars. If such transfers occur, where loading/unloading area drainage does
not flow into a catchment basin or treatment facility designed to handle spills, a quick
drainage system must be used. The containment system must be designed to hold at
least the maximum capacity of any single compartment of a tank car of tank truck
loaded or unloaded at the facility.
Additionally, any piping, equipment, or device not contained within a double-wall
AST is subject to the requirements of §112.8(b)(3) and (4), if such piping, equipment, or
device is in an undiked area.
CONCLUSION/IMPLEMENTATION Should you have any questions concerning this
memorandum, please contact Hugo Fleischman, of my staff, at 703-603-8769.
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OSWER 9360.8-38
Attachment
cc: Michael B. Cook
Elaine Davies
Andrew Gordon
David Drelich
Oil Removal Managers
OERR Records Manager, IMC 5202G
OERR Documents Coordinator, HOSC 5202G
Jeff Josephson, Superfund Lead Region Coordinator, USEPA Region 2
NARPM Co-Chairs
Doug Kodama, Oil Lead Region Coordinator, USEPA Region 2
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