Ideally, an oil container would never leak or overfill. However, history has shown that a primary container that holds oil has the potential to leak or overfill. That means a facility cannot rely on a primary container to prevent discharges from reaching navigable waters and adjoining shorelines. Secondary containment and/or diversionary structures offer temporary containment of oil that discharges from a failed primary container. When designed effectively, they not only give a facility time to fix the primary container and remove the accumulated oil but stop the oil before it can enter a water body, the ultimate goal of oil spill prevention.
General secondary containment
- General secondary containment requirements are intended to contain or hold the most likely oil discharges from an area or container.
The general secondary containment requirements are intended to address, in accordance with good engineering practice, the most likely oil discharges from areas or containers such as mobile refuelers and other non-transportation-related tank trucks; oil-filled operational or process equipment; (non-rack) transfer areas; or piping. The containment method, design, and capacity are determined by good engineering practice to contain or hold the most likely discharge of oil until cleanup occurs. The general secondary containment provision is found at Part 112.7(c).
Requirements
- All areas and equipment with the potential for an oil discharge in quantities that may be harmful are subject to the general secondary containment provision.
At a regulated facility, all areas and equipment with the potential for a discharge are subject to the general secondary containment provision, Part 112.7(c). These may include bulk storage containers; mobile/portable containers; mobile refuelers and other non-transportation-related tank trucks; oil production tank batteries, treatment, and separation installations; pieces of oil-filled operational or manufacturing equipment; and loading/unloading areas (also referred to as transfer areas) and piping and may include other areas of a facility where oil is present. For the areas where specific (sized) secondary containment is also required, this sized secondary containment fulfills the general secondary containment requirements.
The general secondary containment provision requires that these areas be designed with appropriate containment and/or diversionary structures to prevent a discharge in quantities that may be harmful (i.e., a discharge as described in 112.1(b)). “Appropriate containment” must be designed to address the most likely quantity of oil that would be discharged from the primary containment system (e.g., container and equipment), such that the discharge will not escape secondary containment before cleanup occurs. In determining the most likely quantity, the facility owner/operator should consider factors such as the typical failure mode (e.g., overfill, fracture in container wall, etc.), resulting oil flow rate, facility personnel response time, and the duration of the discharge.
Calculations may be provided as part of the documentation to support the adequacy of secondary containment measures employed at the facility, although they are not required. Nevertheless, the Spill Prevention, Control, and Countermeasure (SPCC) Plan preparer must include enough detail in the plan to describe the efficacy of the measures used to comply with the general secondary containment requirements in 112.7(c).
The general secondary containment provision applies to all areas of a facility that have a potential to cause an oil discharge. However, the provision allows for alternative measures in the SPCC Plan for:
- Qualified oil-filled operational equipment; and
- Flowlines and intra-facility gathering lines.
Methods of secondary containment listed in 112.7(c)
- Examples of secondary containment methods include dikes, berms, and retaining walls; drainage systems; booms and other barriers; sorbent materials; and more.
Part 112.7(c) lists several methods of providing secondary containment, which are described in table below. These methods are examples only; other containment methods may be used, consistent with good engineering practice. For example, a facility could use an oil/water separator, combined with a drainage system, to collect and retain discharges of oil within the facility. Professional engineer (PE) certification (or self-certification, in the case of qualified facilities) of Spill Prevention, Control, and Countermeasure (SPCC) Plan includes verification that the selected secondary containment methods for the facility are appropriate and follow good engineering practice.
Secondary containment method | Description of examples |
---|
Dikes, berms, or retaining walls sufficiently impervious to contain oil | Types of permanent engineered barriers, such as raised earth embankments or concrete containment walls, designed to hold oil. Normally used in areas with potential for large discharges, such as single or multiple aboveground storage tanks and certain piping. Temporary dikes and berms may be constructed after a discharge is discovered as an active containment measure (or a countermeasure) so long as they can be implemented in time to prevent the spilled oil from reaching surface waters. For more information, see Passive versus Active Secondary Containment Determination. |
Curbing | Typically consists of a permanent reinforced concrete or an asphalt apron surrounded by a concrete curb. Can also be of a uniform, rectangular cross-section or combined with mountable curb sections to allow access to loading/unloading vehicles and materials handling equipment. Can be used where only small spills are expected and also used to direct spills to drains or catchment areas. Temporary curbing may be constructed after a discharge is discovered as an active containment measure (or a countermeasure) so long as it can be implemented in time to prevent the spilled oil from reaching surface waters. For more information, see Passive versus Active Secondary Containment Determination. |
Culverting, gutters, or other drainage systems | Types of permanent drainage systems designed to direct spills to remote containment or treatment areas. Ideal for situations where spill containment structures cannot or should not be located immediately adjacent to the potential spill source. |
Weirs | Dam-like structures with a notch through which oil may flow to be collected. Generally used in combination with skimmers to remove oil from the surface of water. |
Booms | Form a continuous barrier placed as a precautionary measure to contain/collect oil. Typically used for the containment, exclusion, or deflection of oil floating on water, and is usually associated with an oil spill contingency or Facility Response Plan to address oil spills that have reached surface waters. Beach booms are designed to work in shallow or tidal areas. Sorbent-filled booms can be used for land-based spills. There are very limited applications for use of booms for land-based containment of discharged oil. |
Barriers | Spill mats, storm drain covers, and dams used to block or prevent the flow of oil. Temporary barriers may be put in place prior to a discharge or after a discharge is discovered. These are all considered effective active containment measures (or countermeasures) as long as they can be implemented in time to prevent the spilled oil from reaching navigable waters and adjoining shorelines. For more information, see Passive versus Active Secondary Containment Determination. |
Spill diversion ponds and retention ponds | Designed for long-term or permanent containment of stormwater, but also capable of capturing and holding oil or runoff and preventing it from entering surface water bodies. Temporary spill diversion ponds and retention ponds may be constructed after a discharge is discovered as an active containment measure (or countermeasure) as long as they can be implemented in time to prevent the spilled oil from reaching navigable waters and adjoining shorelines. There are very limited applications for use of temporary spill diversion and retention ponds for land-based containment of discharged oil due to the timely availability of the appropriate excavation equipment required to rapidly construct the ponds. For more information, see Passive versus Active Secondary Containment Determination. |
Sorbent materials | Insoluble materials or mixtures of materials (packaged in forms such as spill pads, pillows, socks, and mats) used to recover liquids through the mechanisms of absorption, adsorption, or both. Materials include clay, vermiculite, diatomaceous earth, and man-made materials. Used to isolate and contain small drips or leaks until the source of the leak is repaired. Commonly used with material handling equipment, such as valves and pumps. Also used as an active containment measure (or countermeasure) to contain and collect small-volume discharges before they reach waterways. Proper use of these materials may require a properly equipped and trained spill response team specifically trained to contain an oil discharge prior to reaching navigable waters or adjoining shorelines. For more information, see Passive versus Active Secondary Containment Determination. |
Drip pans | Used to isolate and contain small drips or leaks until the source of the leak is repaired. Drip pans are commonly used with product dispensing containers (usually drums), when uncoupling hoses during bulk transfer operations, and for pumps, valves, and fittings. |
Sumps and collection systems | A permanent pit or reservoir and its associated troughs/trenches that collect oil. |
Alternative measures related to qualified oil-filled operational equipment
- When providing secondary containment for oil-filled operational equipment is impracticable, Part 112 allows for alternative options for qualified equipment.
Providing adequate secondary containment for oil-filled operational equipment is often impracticable; therefore, Part 112 provides an optional alternative to the general secondary containment requirements for oil-filled operational equipment that meets qualifying criterion in 112.7(k) (commonly referred to as “qualified oil-filled operational equipment”).
Oil-filled operational equipment, as defined in 112.2, is equipment that includes an oil storage container (or multiple containers) in which the oil present is used solely to support the function of the apparatus or the device. Facility owners or operators determine if they are eligible to use the alternative measures in 112.7(k) by considering the reportable discharge history from any oil-filled operational equipment at the facility. The table below identifies the criterion for determining if the facility has qualified oil-filled operational equipment:
Owner/operator must answer no to the following to be eligible for alternative measures in 112.7(k): In the three years before the SPCC Plan is certified, has the facility had any discharges to navigable waters or adjoining shorelines from oil-filled operational equipment as described below? |
A single discharge of oil greater than 1,000 gallons? | Yes or No |
Two discharges of oil each greater than 42 gallons within any 12-month period? | Yes or No |
When considering the above questions, the owner or operator does not need to include discharges that are the result of natural disasters, acts of war, or terrorism. Additionally, when determining the applicability of this spill prevention, control, and countermeasure (SPCC) reporting requirement, the gallon amount(s) specified (either 1,000 or 42) refers to the amount of oil that actually reaches navigable waters or adjoining shorelines, not the total amount of oil spilled. The Environmental Protection Agency (EPA) considers the entire volume of the discharge to be oil for the purposes of these reporting requirements.
Alternative measures
If owners/operators use alternative measures in lieu of meeting the secondary containment requirements for qualified oil-filled operational equipment, they are required to establish and document an inspection or monitoring program for qualified oil-filled operational equipment to detect equipment failure and/or a discharge. Additionally, the owner or operator must prepare an oil spill contingency plan and provide a written commitment of manpower, equipment, and materials required to expeditiously control and remove any quantity of oil discharged that may be harmful (unless the facility has submitted a Facility Response Plan.)
The advantage of the 112.7(k) alternative to the general secondary containment requirements is that the facility owner/operator is not required to prepare an impracticability determination for the qualified oil-filled operational equipment. Note that the use of alternative measures is optional for qualified oil-filled operational equipment; the owner or operator can instead provide secondary containment or may prepare an impracticability determination.
For facility owners and operators who rely on contingency planning for qualified oil-filled operational equipment in lieu of secondary containment, the discovery of a discharge by inspection or monitoring is critical for effective and timely implementation of the contingency plan. An inspection or monitoring program ensures that facility personnel are alerted quickly of equipment failures and/or discharges. The SPCC Plan must describe the inspection or monitoring program, and the owner or operator must keep a record of inspections and tests, signed by the appropriate supervisor or inspector, for a period of three years in accordance with 112.7(e).
Qualified oil-filled operational equipment and qualified facilities overlap
Some facilities may meet the criteria for qualified facilities as provided in 112.3(g) and have qualified oil-filled operational equipment onsite. Owners and operators of such facilities can use the alternative measures for oil-filled operational equipment described in 112.7(k) and self-certify the SPCC Plan. The owner or operator can choose to develop an Oil Spill Contingency Plan, provide a written commitment of manpower, equipment, and materials and implement an inspection or monitoring program as an alternative to secondary containment for qualified oil-filled operational equipment. Since no impracticability determination is necessary for qualified oil-filled operational equipment, the owner or operator can self-certify his or her SPCC Plan and is not required to have a professional engineer (PE) develop and certify the contingency plan for the qualified oil-filled operational equipment. The responsibility of preparing a contingency plan and identifying the necessary equipment, materials, and manpower to implement the contingency plan would fall on the owner or operator of the qualified facility.
Oil-filled manufacturing equipment is not oil-filled operational equipment
The definition of oil-filled operational equipment does not include oil-filled manufacturing equipment (flow-through process). Oil-filled manufacturing equipment is inherently more complicated than oil-filled operational equipment because it typically involves a flow-through process and is commonly interconnected through piping. For example, oil-filled manufacturing equipment may receive a continuous supply of oil, in contrast to the static capacity of other, non-flow-through oil-filled equipment. Examples of oil-filled manufacturing equipment include, but are not limited to, process vessels, conveyances such as piping associated with a process, and equipment used in the alteration, processing or refining of crude oil and other non-petroleum oils, including animal fats and vegetable oils.
Alternative measures related to flowlines and intra-facility gathering lines
- When providing secondary containment for flowlines and gathering lines is impracticable, Part 112 allows for alternative options for qualified equipment.
- The required contingency plan will rely on strong maintenance, corrosion protection, testing, recordkeeping, and inspection procedures.
Flowlines are typically found at oil production facilities. Flowlines are piping that transfer crude oil and well fluids from the wellhead to the tank battery where separation and treatment equipment are typically located. Flowlines may also connect a tank battery to an injection well. Depending on the size of the oil field, flowlines may range in diameter and run from hundreds of feet to miles between the wellheads and the tank batteries or primary separation operations.
The term gathering lines refers to piping or pipelines that transfer crude oil product between tank batteries, within or between facilities. Gathering lines often originate from an oil production facility’s lease automatic custody transfer (LACT) unit, which transfers oil to other facilities involved in gathering, refining or pipeline transportation operations. The Environmental Protection Agency (EPA) considers gathering lines subject to EPA’s jurisdiction if they are located within the boundaries of an otherwise regulated spill prevention, control, and countermeasure (SPCC) or Facility Response Plan (FRP) facility (that is, intra-facility gathering lines). Note that intra-facility gathering lines subject to the Department of Transportation (DOT) requirements at 49 CFR 192 or 195 are exempt from Part 112 entirely.
Secondary containment is, in many cases, impracticable for flowlines and intra-facility gathering lines. For example, an oil production facility in a remote area may have many miles of flowlines and gathering lines, around which it would not be practicable to build permanent containment structures. It may not be possible to install secondary containment around flowlines running across a farmer’s or rancher’s fields since berms may become severe erosional features and can impede access to the fields by tractors and other farm/ranch equipment. Similarly, it may be impracticable to construct secondary containment around flowlines that run along a fence or county road due to space limitations or intrusions into a county’s property or right-of-way. At unattended facilities, active secondary containment methods are not effective in meeting secondary containment requirements because there is limited capability to detect a discharge and deploy active measures in a timely fashion.
Therefore, 112.9(d)(3) provides an optional alternative to the general secondary containment requirements for flowlines and intra-facility gathering lines that are subject to the SPCC rule. In lieu of secondary containment, the facility owner or operator may implement an Oil Spill Contingency Plan in accordance with Part 109 (Criteria for State, Local and Regional Oil Removal Contingency Plans) and have a written commitment of manpower, equipment, and materials required to expeditiously control and remove any quantity of oil discharged that may be harmful. These requirements are the same as those in 112.7(d); however, the plan does not need to include an impracticability determination for each flowline and intra-facility gathering line.
The contingency plan required when secondary containment is not practicable for flowlines and intra-facility gathering lines should rely on strong maintenance, corrosion protection, testing, recordkeeping, and inspection procedures to prevent and quickly detect discharges from such lines. It should also ensure quick availability and deployment of response equipment. An effective flowline maintenance program is necessary to detect a discharge in a timely manner so that the oil discharge response operations described in the contingency plan may be implemented effectively.
Additionally, eliminating the requirement for secondary containment means that more prescriptive requirements are needed for discharge prevention to ensure the integrity of the primary containment of the pipe itself. The SPCC rule requires a performance-based program of flowline and intra-facility gathering line maintenance, in accordance with 112.9(d)(4), that addresses the facility owner or operator’s procedures and must be documented in their SPCC Plan.
The complexity or simplicity of a facility’s contingency plan is subject to good engineering practice as determined by the SPCC Plan certifier. EPA developed a model contingency plan (see Appendix F of the SPCC Guidance for Regional Inspectors). This model contingency plan is intended as an example and inspectors should only use it for this purpose.
Specific (sized) secondary containment
- Certain types of containers, activities, or equipment that have potential for oil discharge may be subject to more stringent requirements.
While all parts of a regulated facility with potential for a discharge are, at a minimum, subject to the general secondary containment requirements of 112.7(c), areas where certain types of containers, activities, or equipment are located may be subject to additional, more stringent containment requirements, including specifications for minimum capacity.
Specific secondary containment addresses the potential of oil discharges from areas of a facility where oil is stored or handled. Specific secondary containment is often called “sized” secondary containment because the containment is sized to hold the quantity from the largest single container plus sufficient freeboard (for precipitation).
The containment design, sizing, and freeboard requirements are specified by Part 112 to address a major container failure (e.g., the entire contents of the container and/or compartment) from a bulk storage container; single compartment of a tank car or tank truck at a loading/unloading rack; mobile/portable containers; and production tank batteries, treatment, and separation installations (including flow-through process vessels and produced water containers).
Requirements
- The SPCC rule specifies a minimum size for secondary containment for loading and unloading racks; for bulk storage containers; and production facility containers such as tank batteries and separation and treatment equipment.
The spill prevention, control, and countermeasure (SPCC) rule (Part 112 Subparts A to C) specifies a required minimum size for secondary containment for the following areas:
- Loading/Unloading racks;
- Bulk storage containers including mobile or portable containers (does not apply to mobile refuelers or other non-transportation-related tank trucks); and
- Production facility bulk storage containers, including tank batteries, separation, and treating equipment (e.g., produced water tanks).
In general, provisions for specific secondary containment require that the chosen containment method be sized to contain the largest single oil compartment or container plus “sufficient freeboard” to contain precipitation.
Note that the “largest single compartment” may consist of several containers that are permanently manifolded together. Permanently manifolded tanks are tanks that are designed, installed, or operated in such a manner that the multiple containers function as a single storage unit. Accordingly, the total capacity of manifolded containers is the design capacity standard for the sized secondary containment provisions (plus freeboard in certain cases).
While the rule does not require that secondary containment calculations be kept in the SPCC Plan, EPA strongly recommends that the facility owner or operator maintain the calculations such that if questions arise during an inspection, the calculations which serve as the basis for the capacity of the secondary containment system will be readily available for review by the EPA inspector. Industry guidance also recommends that facility owners or operators include any secondary containment capacity calculations and/or design standards with the plan.
Sufficient freeboard
- Part 112 does not define the term “sufficient freeboard,” but EPA has used the amount of precipitation produced from a 25-year, 24-hour storm event to be one appropriate measure.
The Oil Pollution Prevention Standard at Part 112 does not specifically define the term “sufficient freeboard,” nor does it describe how to calculate this volume. The 1991 proposed amendment to the regulation recommended the use of industry standards and data on 25-year storm events to determine the appropriate freeboard capacity.
Numerous commenters on the 1991 proposal questioned the 25-year storm event recommendation and suggested alternatives, such as using 110 percent of storage tank capacity or using other characteristic storm events. The Environmental Protection Agency (EPA) addressed these comments in the preamble to the July 17, 2002, amendments to the rule:
- “We believe that the proper standard of “sufficient freeboard” to contain precipitation is that amount necessary to contain precipitation from a 25-year, 24-hour storm event. That standard allows flexibility for varying climatic conditions. It is also the standard required for certain tank systems storing or treating hazardous waste.”
However, Part 112 did not set this standard as a requirement for freeboard capacity. Therefore, the use of precipitation data from a 25-year, 24-hour storm event is not enforceable as a standard for containment freeboard. In the July 17, 2002, preamble, EPA further stated:
- “While we believe that the 25-year, 24-hour storm event standard is appropriate for most facilities and protective of the environment, we are not making it a rule standard because of the difficulty and expense for some facilities of securing recent information concerning such storm events at this time.”
Ultimately, EPA determined that, for freeboard, “the proper method of secondary containment is a matter of engineering practice so [EPA does] not prescribe here any particular method.” However, where data are available, the facility owner/operator (and/or certifying professional engineer) may want to consider the appropriateness of the 25-year, 24-hour storm event precipitation design criteria for containment freeboard.
110-percent rule
A “110 percent of storage tank capacity” rule of thumb may be an acceptable design criterion in many situations, and aboveground storage tank regulations in many states require secondary containment to be sized to contain at least 110 percent of the volume of the largest tank. However, in some situations, 110 percent of storage tank capacity may not provide enough volume to contain precipitation from storm events. Some states require that facilities consider storm events when designing secondary containment structures, and in certain cases these requirements translate to more stringent sizing criteria than the 110 percent rule of thumb.
Other factors to consider
Other important factors may be considered in determining necessary secondary containment capacity. According to practices recommended by industry groups such as the American Petroleum Institute (API), these factors include:
- Local precipitation conditions (rainfall and/or snowfall),
- Height of the existing dike wall,
- Size of tank/container,
- Safety considerations, and
- Frequency of dike drainage and inspection.
The certifying professional engineer (or owner/operator, in the case of qualified facilities) determines what volume constitutes sufficient freeboard for precipitation for secondary containment and should document in the Spill Prevention, Control, and Countermeasure (SPCC) Plan how the determination was made.
Sufficiently impervious
- Secondary containment structures such as dikes, berms, and retaining walls can be considered sufficiently impervious if they allow for cleanup to occur in time to prevent a discharge to navigable waters or adjoining shorelines.
Part 112 calls for diked areas, berms, or retaining walls to be “sufficiently impervious to contain oil.” Dikes, berms, and retaining walls are types of secondary containment. Effective secondary containment methods must be able to contain oil until the oil is cleaned up.
However, Part 112 does not specify permeability, hydraulic conductivity, or retention time performance criteria for these provisions (i.e., “sufficiently impervious” does not necessarily mean indefinitely impervious). Instead, the owner or operator and/or the certifying professional engineer (PE) have the flexibility to determine how best to design the containment system to prevent a discharge to navigable waters or adjoining shorelines.
This determination is based on a good engineering practice evaluation of the facility configuration, product properties, and other site-specific conditions. For example, a sufficiently impervious retaining wall, dike, or berm, including the walls and floors, must be constructed so that any discharge from a primary containment system will not escape the secondary containment system before cleanup occurs and before the oil reaches navigable waters or adjoining shorelines (112.7(c), 112.8(c)(2) and 112.12(c)(2)).
In other words, secondary containment structures such as dikes, berms, and retaining walls can be considered sufficiently impervious as long as they allow for cleanup to occur in time to prevent a discharge to navigable waters or adjoining shorelines. Ultimately, the determination of imperviousness should be verified by a PE and documented in the Spill Prevention, Control, and Countermeasure (SPCC) Plan.
The preamble to a July 17, 2002, the Environmental Protection Agency (EPA) final rule states that “a complete description of how secondary containment is designed, implemented, and maintained to meet the standard of sufficiently impervious is necessary.” Therefore, pursuant to 112.7(a)(3)(iii) and (c), the SPCC Plan should address how the secondary containment is designed to effectively contain oil until it is cleaned up.
Control and/or removal of vegetation may be necessary to maintain the imperviousness of the secondary containment and to allow for the visual detection of discharges. The owner or operator should monitor the conditions of the secondary containment structure to ensure that it remains impervious to oil. Repairs of excavations or other penetrations through secondary containment need to be conducted in accordance with good engineering practice.
The earthen floor of a secondary containment system may be considered “capable of containing oil” until cleanup occurs, or “sufficiently impervious” if there is no subsurface conduit allowing the oil to reach navigable waters before it is cleaned up. Should oil reach navigable waters or adjoining shorelines, it is a reportable discharge under Part 110. The suitability of earthen material for secondary containment systems may depend on the properties of both the product stored and the soil. For example, compacted local soil may be suitable to contain a viscous product, such as liquid asphalt cement, but may not be suitable to contain gasoline. Permeability through the wall (or wall-to-floor interface) of the structure may result in a discharge to navigable waters or adjoining shorelines and must be carefully evaluated.
In certain geographic locations, the native soil (e.g., clay) may be determined as sufficiently impervious. However, in many more instances good engineering practice would generally not allow the use of a facility’s native soil alone as secondary containment when the soil is not homogenous. In fact, certain state requirements may restrict the use of soil as a means of secondary containment, and many state regulations explicitly forbid the discharge of oil on soil. Facility owners and operators must investigate and comply with all state and local requirements.
Discharges to soil and groundwater may violate other federal regulations (and violate Section 311(b)(3) of the Clean Water Act (CWA) if an oil discharge to groundwater impacts a navigable waterway or adjoining shoreline).
In summary, the owner or operator must base determinations of sufficiently impervious secondary containment design on good engineering practice and site-specific considerations, and this must be documented in the SPCC Plan.
Other issues
Several other issues are related to all secondary containment, whether general or specific (sized).
Passive and active secondary containment
- Passive secondary containment includes permanent installations that do not require deployment or action by the facility owner or operator but remain in place regardless of the facility operations.
- Active secondary containment includes measures that require deployment or other specific action by the facility owner or operator before or once a discharge occurs.
Passive secondary containment
Passive secondary containment includes permanent installations that do not require deployment or action by the facility owner or operator but remain in place regardless of the facility operations. Examples include dikes, berms, retaining walls, curbing, culverting, gutters, drainage, weirs, booms, barriers, diversion, retention ponds, drip pans, sumps, and collection systems.
Active secondary containment
Active secondary containment includes measures that require deployment or other specific action by the facility owner or operator before or once a discharge occurs. These actions are also referred to as spill countermeasures and designed to prevent an oil spill from reaching navigable water or adjoining shorelines. Active measures (countermeasures) include, but are not limited to:
- Placing a properly designed storm drain cover over a drain to contain a potential spill in an area where a transfer occurs, prior to the transfer activity. Storm drains are normally kept uncovered; deployment of the drain cover prior to the transfer activity may be an acceptable active measure to prevent a discharge from reaching navigable waters or adjoining shorelines through the drainage system.
- Placing a storm drain cover over a drain in reaction to a discharge before the oil reaches the drain. If deployment of a drain cover can reliably be achieved in time to prevent a discharge of oil from reaching navigable waters or adjoining shorelines, this may be an acceptable active measure. This method may be risky, however, and is subject to a good engineering judgment on what is realistically and reliably achievable, particularly under adverse circumstances.
- Using spill kits in the event of an oil discharge. The use of spill kits, strategically located and ready for deployment in the event of an oil discharge, may be an acceptable active measure, in certain circumstances, to prevent a spill from reaching navigable waters or adjoining shorelines. This method may be risky and is subject to good engineering judgment, considering the volume most likely expected to be discharged and proximity to navigable waters or adjoining shorelines.
- Use of spill response capability (spill response teams) in the event of an oil discharge. This method differs from activating an Oil Spill Contingency Plan (see Part 112.7(d)) because the response actions are specifically designed to contain an oil discharge prior to reaching navigable waters or adjoining shorelines. Such actions may include the emergency construction/deployment of dikes, curbing, diversionary structures, ponds, and other temporary containment methods (such as sorbent materials), so long as they can be implemented in time to prevent the spilled oil from reaching navigable waters or adjoining shorelines. This method may be risky and reliance on oil spill response capability for secondary containment is subject to good engineering judgment.
- Closing a gate valve that controls drainage from an undiked area prior to a discharge. If the gate valve is normally kept open, closing it before an activity that may result in an oil discharge may be an acceptable active measure to prevent a spill from reaching navigable waters or adjoining shorelines. Note that the Environmental Protection Agency (EPA) requires that bypass valves for diked areas be sealed closed (112.8(c)(3)(i) and 112.12(c)(3)(i)).
Passive versus active secondary containment determination
- In some cases, passive secondary containment may not be feasible; in those cases, active containment measures may be used.
- The efficacy of active containment measures to prevent a discharge depends on their technical effectiveness, placement and quantity, and how quickly they can be deployed to immediately contain a discharge.
In some situations, dikes and other permanent containment structures known as passive secondary containment may not be feasible. For example, they may cause pooling of liquids around electrical equipment which may present a hazard. Part 112.7(c) specifically allows for the use of active containment measures (countermeasures or spill response capability that require deployment or action) to prevent a discharge to navigable waters or adjoining shorelines.
The use of active containment as a strategy to address discharges should be carefully evaluated. The efficacy of active containment measures to prevent a discharge depends on their technical effectiveness (e.g., mode of operation, absorption rate), placement and quantity, and timely deployment prior to or following a discharge. For discharges that occur only during attended or observed activities, such as those occurring during transfers, an active measure (e.g., sock, mat, other portable barrier, or land-based response capability) may be appropriate, provided that the measure is capable of containing the most likely volume of an oil discharge from a typical failure mode and is timely and properly constructed and deployed. Ideally, in order to further reduce the potential for an oil discharge to reach navigable waters or adjoining shorelines, the active measure should be deployed prior to initiating the activity with potential for a discharge.
For certain active measures, however, such as the use of “kitty litter” or other sorbent material, it may be impractical to pre-deploy the measure. In such cases, the sorbent material should be readily available so that it can be used immediately after a spill occurs but before it can spread. Portable tanks can be equipped with a spill kit to be used in the event of a discharge during transfers. The spill kit should be sized to effectively contain the volume of oil that could be discharged. Most commercially available spill kits are intended for relatively small volumes (up to approximately 150 gallons of oil).
Active containment measures can be used to satisfy the general secondary containment requirement when they are capable of containing the most likely discharge volume identified in the Spill Prevention, Control, and Countermeasure (SPCC) Plan. Elements to consider may include the capacity of the containment measure, effectiveness, timely implementation, and the availability of facility personnel and equipment to implement the active measure effectively. For example, a discharge of 600 gallons would require deploying more than 900 “high-capacity” sorbent pads (20 inches by 20 inches) since each pad absorbs less than 0.7 gallons of oil. The same spill volume would require nine sorbent blankets, each measuring 38 inches by 144 feet and weighing approximately 40 pounds. The rapid deployment of such response equipment and material would be difficult to achieve under most circumstances, particularly if only a few individuals are present when the discharge occurs, or during adverse conditions (e.g., rainfall, fire).
Using an active measure to meet the specific secondary containment requirement for a bulk storage container may be difficult because the containment system must be sized for the entire capacity of the bulk oil storage container. Therefore, the use of active measures for larger oil containers may not be appropriate or in accordance with good engineering practice or sound industry standards.
In certain circumstances, sorbents, such as socks, booms, pads, or loose materials may be used to complement passive measures. For example, where berms around transfer areas are open on one side for access, and where the ground surface slopes away from the opening with no nearby drains, sorbent material may be effective in preventing small quantities of oil from escaping the bermed area in the event of a discharge.
The secondary containment approach implemented at a facility need not be one size fits all. Different approaches may be taken for the same activity at a given facility, depending on the material and location. For example, the SPCC Plan may specify that drain covers and sorbent material be pre-deployed prior to transfers of low viscosity oils in certain areas of a facility located in close proximity to drainage structures or navigable waters. For other areas and/or other products (e.g., highly viscous oils), the plan may specify that sufficient spill response capability (spill response teams) are available for use in the event of a discharge, so long as personnel and equipment are available at the facility and these measures can be effectively implemented in a timely manner to prevent oil from reaching navigable waters or adjoining shorelines.
Evaluating the ability of active secondary containment measures deployed after a discharge to prevent oil from reaching navigable waters or adjoining shorelines involves considering the time it would take to discover the discharge, the time for the discharge to reach navigable waters or adjoining shorelines, and the time necessary to deploy the active secondary containment measure. For some active containment measures such as the use of sorbent materials, the amount of oil the secondary containment measure can effectively contain, including the potential impact of precipitation on sorption capacity, is also a critical factor. Good engineering practice would indicate that active secondary containment measures may be used to satisfy the general secondary containment requirements of 112.7(c) only in certain circumstances.
The use of an active measure containment strategy can be risky if not properly designed, evaluated, and implemented. If an active measure fails to prevent an oil discharge from reaching navigable waters or adjoining shorelines, the owner or operator is liable for the discharge and cleanup and is responsible for properly reporting it to the National Response Center. Furthermore, even when used to comply with 112.7(c), active measures should be limited to those situations where a professional engineer (PE) has determined that the typical failure mode involves a small volume of oil. Generally, active containment measures are not appropriate for satisfying the specific containment requirements for a major container failure. Environmental Protection Agency (EPA) inspectors may closely review the SPCC Plan and evaluate the rationale, equipment, and implementation of such a strategy, as in most cases, this would not be considered good engineering practice.
The SPCC Plan must describe the procedures used to deploy the active measures, explain how the use of active measures is appropriate to the situation, and explain the methods for discharge discovery that will be used to determine when deployment of the active measures is appropriate (112.7(a)(3)(iii) and (iv)).
Facility drainage
- Facility drainage requirements are design standards, not additional secondary containment requirements. Requirements vary based on the type of facility and the features of the containment area.
The facility drainage requirements of Part 112.8(b) and 112.12(b) are design standards for secondary containment (not additional secondary containment requirements) and are therefore eligible for deviations that provide equivalent environmental protection in compliance with 112.7(a)(2) and as determined appropriate by a professional engineer (PE).
Facility drainage control from diked areas
When a dike (the term as used here also includes other barrier methods such as berms, retaining walls, curbing, weirs, or booms) is used as the containment method to satisfy either general or specific secondary containment requirements, then facility drainage requirements also apply. The requirements for diked areas at onshore facilities (except oil production facilities) are found in 112.8(b)(1) and 112.8(b)(2) (or 112.12(b)(1) and 112.12(b)(2)). For diked areas at onshore oil production facilities, they are found in 112.9(b)(1).
Drainage from diked storage areas can be accomplished by several means such as valves, manually activated pumps, or ejectors. If dikes are drained using valves, they must be of manual design to prevent an uncontrolled discharge outside of the dike, such as into a facility drainage system or effluent treatment system, except where facility systems are designed to control such a discharge (112.8(b)(1) and 112.12(b)(1)). Although not required by the regulation, owners and operators should strongly consider locking valves controlling dike or remote impoundment areas, especially when they can be accessed by non-facility personnel.
For diked areas serving as secondary containment for bulk storage containers, 112.8(c)(3) and 112.12(c)(3) require that stormwater accumulations be inspected for the presence of oil and that records of the drainage events be maintained. Prior to draining these areas, accumulated oil on the rainwater must be removed and returned to storage or disposed of in accordance with legally approved methods.
Facility drainage control from undiked areas
When secondary containment requirements are addressed through facility drainage controls, such as culverting, gutters, ponds, or other drainage systems, the requirements in 112.8(b)(3) and (4), or 112.12(b)(3) and (4) apply. For example, a facility may choose to use the existing storm drainage system to meet secondary containment requirements by channeling discharged oil to a remote containment area to prevent a discharge to navigable waters or adjoining shorelines. The facility drainage system must be designed to flow into ponds, lagoons, or catchment basins designed to retain oil or return it to the facility. Catchment basins must not be located in areas subject to periodic flooding (112.8(b)(3) and 112.12(b)(3)).
Conversely, the owner or operator of a facility does not have to address the undiked area requirements of 112.8(b)(3) and (4) or 112.12(b)(3) and (4) if the facility does not use drainage systems to meet one of the secondary containment requirements in the spill prevention, control, and countermeasure (SPCC) rule. For example, if the SPCC Plan documents the use of an active containment measure (such as a combination of sorbents and a spill mat) that is effective to prevent a discharge to navigable waters or adjoining shorelines, then secondary containment has been provided and it is not necessary to alter drainage systems at the facility. The facility drainage system design requirements in 112.8(b)(3) and (4) or 112.12(b)(3) and (4) apply only when the facility uses these drainage systems to comply with the secondary containment provisions of the rule.
The following examples help to illustrate how to determine the appropriate size of the ponds, lagoons, or catchment basins:
- General secondary containment. A facility owner/operator may use a stormwater drainage system that flows to a containment pond to address the general secondary containment requirements of 112.7(c) for a piece of operational equipment (including electrical oil-filled equipment). The secondary containment system must be designed to address the typical failure mode and to contain the volume of oil most likely to be discharged as determined according to good engineering practice and documented in the SPCC Plan (not necessarily a complete/major container failure).
- Specific secondary containment. If a facility owner/operator uses a stormwater drainage system that flows to a catchment basin to comply with the specific secondary containment requirements for a bulk storage container, the secondary containment system must be designed to contain the capacity of the largest bulk storage container located inside the containment system (with appropriate freeboard for precipitation) as dictated by the rule’s requirements in 112.8(c)(2) or 112.12(c)(2). The specific secondary containment requirement is based on a worst-case container failure in which the entire capacity of the container is discharged.
- General and specific secondary containment. In a case where a drainage system to a final catchment basin is used to meet multiple secondary containment needs for the facility, including compliance with both general and specific secondary containment requirements, the system’s design will need to meet the most stringent rule requirement (typically sized for the specific secondary containment requirement).
Oil production facility drainage
Owners and operators of oil production facilities must close and seal drains on secondary containment systems associated with tank batteries and separation and treating areas (both dikes and other equivalent measures required under Part 112.7(c)(1)) at all times, except when draining uncontaminated rainwater (112.9(b)(1)). Prior to drainage, the owner/operator must inspect the diked area and take action as provided in 112.8(c)(3)(ii), (iii), and (iv). If oil is present, then the owner/operator must remove accumulated oil on the rainwater and return it to storage or dispose of it in accordance with legally approved methods.
Owners and operators of oil production facilities must also inspect field drainage systems (such as drainage ditches or road ditches), and oil traps, sumps, or skimmers at regularly scheduled intervals for an accumulation of oil that may have resulted from any small discharge and promptly remove any accumulations of oil from these systems. Environmental Protection Agency (EPA) inspectors should evaluate facility records to verify compliance with the drainage procedures described in 112.8(c)(3). Any stormwater discharge records maintained at the facility in accordance with the National Pollutant Discharge Elimination System (NPDES) requirements in Part 122.41(j)(2) or 122.41(m)(3) are acceptable to satisfy the recordkeeping requirements of 112.8(c)(3)(iv) or 112.12(c)(3)(iv). Field observations may also shed light on compliance with the drainage provisions of the rule.
Man-made structures
- To the extent that an existing building structure meets the SPCC performance criteria for secondary containment, the owner or operator can consider such a building as an appropriate containment structure.
If an oil storage container at a regulated facility is located inside a building, the professional engineer (PE) certifying the Spill Prevention, Control, and Countermeasure (SPCC) Plan may take into consideration the ability of the building walls and/or drainage systems to serve as secondary containment. The SPCC rule (Part 112 Subparts A to C) is performance based and provides flexibility to the facility owner or operator in terms of how to design and implement secondary containment to provide adequate protection.
The rule provides general design criteria for secondary containment of bulk storage containers by requiring that the containment system be sized to contain the capacity of the largest container, with freeboard for precipitation, as appropriate. The SPCC rule does not specify a volume amount to account for precipitation (e.g., 110 percent of capacity); instead, it allows the facility owner or operator, or the PE certifying the SPCC Plan, to consider location-specific conditions, including the possibility that a bulk storage container is located indoors where precipitation is not a factor. When secondary containment is provided inside a building, freeboard calculations for precipitation are typically not applicable.
The SPCC rule also requires that the containment structure provided around bulk storage containers be sufficiently impervious to oil. Any indoor drainage system that leads directly to a storm sewer (discharging into a stream), a sanitary sewer (discharging into a Publicly Owned Treatment Works (POTW)), or otherwise directly into a water body may serve as a conduit for a discharge to navigable waters or adjoining shorelines.
Therefore, the containment structure must not be equipped with open floor drains or an automated sump pump unless the drainage system has been purposefully equipped to treat any discharge (e.g., by use of an adequately sized, designed, and maintained oil-water separator). Additionally, any doorways, windows, or other openings that would permit a discharge to flow out of the building must also be taken into consideration.
To the extent that an existing building structure meets the SPCC performance criteria for secondary containment, the owner or operator can consider such a building as an appropriate containment structure. In cases where the building walls are used for secondary containment, the calculation of the capacity of the secondary containment structure would need to consider the displacement by other containers, equipment, and items sharing the containment structure.
Where applicable, containers may be subject to the National Fire Protection Association’s (NFPA’s) Flammable and Combustible Liquids Code (NFPA 30) in addition to the SPCC requirements. For containers located in buildings, NFPA 30 prescribes specific requirements to control fire hazards involving flammable or combustible liquids. Facility drainage and other design/construction provisions are listed in NFPA 30. According to EPA, if a facility is designed, constructed, and maintained to applicable fire codes, such as NFPA 30, the building may serve as secondary containment under the SPCC rule.
Double-walled or vaulted tanks or containers
- Double-walled and vaulted tanks are subject to secondary container requirements.
- In the case of double-walled tanks, those that meet qualifying criteria generally comply with secondary containment requirements.
Double-walled or vaulted tanks are subject to secondary containment requirements. Double-walled tank and vaulted tank are defined in Covered facilities.
In the case of vaulted tanks, the Spill Prevention, Control, and Countermeasure (SPCC) Plan preparer must determine whether the vault meets the requirements for secondary containment in Part 112.7(c). This determination should include an evaluation of drainage systems and of sumps or pumps which could cause a discharge of oil outside the vault. Industry standards for vaulted tanks often require the vaults to be liquid tight, which if sized correctly, may meet the secondary containment requirement. There might also be other examples of such alternative systems.
The Environmental Protection Agency (EPA) issued two memorandums to address how the secondary containment requirements of 112.7(c) apply to double-walled tanks. In the first memo, issued April 29, 1992, EPA described that shop-fabricated aboveground double-walled tanks that meet certain industry construction standards, with capacities less than 12,000 gallons, installed and operated with protective measures such as overfill alarms, flow shutoff or restrictor devices, and constant monitoring of product transfers would generally comply with the secondary containment requirements of 112.7(c).
As an alternative to the overfill prevention measures to contain discharges from a double-walled tank, active or passive measures of secondary containment may be used to contain overfills from tank vents that may occur during transfer operations. The 1992 memo was amended on August 9, 2002, to remove the 12,000-gallon tank capacity limitation and to discuss additional SPCC requirements that apply to double-walled tanks.
Shop-fabricated double-wall ASTs, regardless of size, may generally satisfy not only the secondary containment requirements of 112.7(c), but also the specific secondary containment requirements for sizing secondary containment for bulk storage containers found at 112.8(c)(2). Double-walled tanks typically do not require additional freeboard for precipitation when the interstice is not exposed to precipitation. Double-walled tanks that store animal fats or vegetable oils may generally satisfy the secondary containment requirements of 112.12(c)(2).
Double-walled tanks with fittings or openings (e.g., a manway) located below the liquid level of the container may require additional secondary containment to conform with industry standards and/or local codes.
Summary of required elements from the double-walled tank memos:
The use of certain shop-built double-wall aboveground storage tanks (ASTs) serve as an “equivalent” preventive system for purposes of the general secondary containment requirements of 112.7(c) when they include the following elements:
- Containers are shop fabricated;
- The inner tank is an Underwriter Laboratories (UL) listed steel tank;
- The outer tank is constructed in accordance with nationally accepted industry standards (e.g., American Petroleum Institute (API), Steel Tank Institute (STI), the American Concrete Institute);
- The tank is equipped with the following overfill prevention measures to contain overfills from tank vents:
- Overfill alarm, and
- Automatic flow restrictor or flow shut-off; and
- All product transfers are constantly monitored.
As an alternative to the overfill prevention measure described in the fourth bullet above, the container may be equipped with either active or passive secondary containment methods to address the typical failure mode and the most likely quantity of oil that would be discharged from the tank’s vents during transfer operations.
Inspection requirements for double-walled tanks
Section 112.8(c)(6) requires the owner or operator to conduct integrity testing on a regular schedule and whenever repairs are made. The section also requires the owner or operator to frequently inspect the outside of the container for signs of deterioration, discharges, or accumulation of oil inside diked areas (for a double-walled tank, this inspection requirement applies to the inner tank).
Other applicable secondary containment requirements
While shop-fabricated double-wall ASTs may satisfy the requirements of 112.7(c) and 112.8(c)(2), such tanks, associated appurtenances/piping and transfer activities are also subject to 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 the facility transfers oil in bulk to double-wall 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 or tank truck loaded or unloaded at the facility. Transfer areas (those not associated with a loading/unloading rack) need to comply with the general secondary containment requirements in 112.7(c).
Additionally, any piping, equipment, or device not contained within a double-walled AST is subject to the general secondary containment requirements of 112.7(c). If a facility drainage system will be used to comply with secondary containment then the piping, equipment or device is also subject to requirements of 112.8(b) or 112.12(b).
Mobile and portable containers (except for mobile refuelers and other non-transportation-related tank trucks)
- Most mobile or portable oil storage containers must comply with secondary containment requirements. The appropriate containment method may vary depending on the activity the container is being used for at a given time.
Mobile or portable oil storage containers with a capacity to store 55 gallons or more of oil and operating exclusively within the confines of a non-transportation-related facility are regulated under the spill prevention, control, and countermeasure (SPCC) rule (Part 112 Subparts A to C). With the exception of mobile refuelers and other non-transportation related tank trucks, such containers must comply with the secondary containment requirements of 112.8(c)(11) (or 112.12(c)(11) in the case of a facility that stores or handles animal fats or vegetable oils).
Examples of mobile portable containers include, but are not limited to, 55-gallon drums, skid tanks, totes, and intermediate bulk containers (IBCs).
According to 112.8(c)(11) and 112.12(c)(11), mobile or portable containers (excluding mobile refuelers and other non-transportation-related tank trucks) must be positioned or located to prevent a discharge as described in 112.1(b). These provisions require that the secondary containment be sized to hold the capacity of the largest single compartment or container with sufficient freeboard to contain precipitation.
The appropriate containment methods for mobile containers may vary depending on the activity in which the container is engaged at a given time. Thus, secondary containment requirements may be met differently depending upon the type of operation being performed.
When mobile containers, such as drums, skids, and totes, are in a stationary mode, the requirements of 112.8(c)(11) and 112.12(c)(11) may be met through the use of permanent secondary containment methods, such as dikes, curbing, drainage systems, and catchment basins. In order to comply with this requirement, an owner or operator may designate an area of the facility in which to locate mobile containers when not in use. This area must be designed, following good engineering practices, to hold the capacity of the largest single compartment or container with sufficient freeboard to contain precipitation. The area designated for mobile portable containers must be identified on the facility diagram provided within the SPCC Plan (112.7(a)(3)).
While in use, mobile containers, such as drums, skids, and totes, must also comply with the requirements of 112.8(c)(11) or 112.12(c)(11) according to good engineering practice, and the areas where the containers are used must be marked on the facility diagram. For these types of containers, the Environmental Protection Agency (EPA) inspector may verify that the secondary containment methods are appropriate to prevent a discharge to navigable waters or adjoining shorelines. For example, an oil-filled drum positioned for use at a construction site must be equipped with secondary containment sized in accordance with 112.8(c)(11).
The facility owner or operator may determine that it is impracticable to provide sized secondary containment in accordance with 112.8(c)(11), when the container is in use at the facility, or the general containment of 112.7(c), pursuant to 112.7(d). If so, then the SPCC Plan must properly explain why secondary containment is impracticable and document the implementation of the alternative regulatory requirements of 112.7(d).
Mobile refuelers and other non-transportation related tank trucks
- Mobile refuelers may be excluded from sized secondary containment requirements; however, general secondary containment and bulk storage container rules still apply.
When mobile containers meet the definition of mobile refuelers, in 112.2, then they are excluded from the sized secondary containment requirements for bulk storage containers. Providing sized secondary containment for vehicles that move frequently within a non-transportation-related facility to perform refueling operations can raise safety and security concerns. However, the general secondary containment requirements at 112.7(c) still apply. Furthermore, since mobile refuelers are a subset of bulk storage containers, the other provisions of 112.8(c) and 112.12(c) also still apply.
The definition of mobile refueler describes vehicles of various sizes equipped with a bulk storage container such as a cargo tank or tank truck that is used to fuel or defuel aircraft, motor vehicles, locomotives, tanks, vessels or other oil storage containers, including full trailers and tank semi-trailers. The definition also includes nurse tanks, which are mobile vessels used at farms to store and transport fuel for transfers to or from farm equipment, such as tractors and combines, and to other bulk storage containers, such as containers used to provide fuel to wellhead/relift pumps at rice farms. A nurse tank is often mounted on a trailer for transport around the farm, and this function is consistent with that of a mobile refueler.
The exemption from sized secondary containment for mobile refuelers also applies to other non-transportation-related tank trucks. Other non-transportation-related tank trucks may operate similarly to mobile refuelers, though not specifically transferring fuel. Instead, these tank trucks may carry other oils such as transformer oils, lubrication oils, crude oil, condensate, or non-petroleum oils such as animal fats and vegetable oils.
Examples include a truck used to refill oil-filled equipment at an electrical substation and a pump truck at an oil production facility. These tank trucks may have the same difficulty in complying with the sized secondary containment requirements as mobile refuelers. Therefore, all non-transportation-related tank trucks are excluded from the sized secondary containment requirements for bulk storage containers; however, the general secondary containment requirements at 112.7(c) apply.
Vehicles used to store oil, operating as onsite fueling vehicles within locations such as construction sites, military or civilian remote operations support sites, or rail sidings are generally considered non- transportation-related. Indicators of when a vehicle is intended to be used as a storage tank (and therefore considered non-transportation-related) include, but are not limited to:
- The vehicle is not licensed for on-road use;
- The vehicle is fueled onsite and never moves off-site; or
- The vehicle is parked on a home-base facility and is filled up off-site but then returns to the home base to fuel other equipment located exclusively within the home-base facility, and only leaves the site to obtain more fuel.
The exemption from sized secondary containment requirements does not apply to vehicles that are used primarily to store oil in a stationary location, such as tanker trucks used to supplement storage and serving as a fixed tank. An indicator that a vehicle is intended to store oil in a fixed location is that the vehicle is no longer mobile (e.g., it is hard-piped or permanently parked, or that the tank car has been separated from the cab of the truck).
Oil-filled operational equipment
- Oil-filled operational equipment poses unique challenges to containment measures; if passive or active containment measures are not feasible, additional requirements must be implemented.
Oil-filled operational equipment (e.g., electrical transformers, capacitors, switches) poses unique challenges; permanent (passive) containment structures, such as dikes, may not always be feasible. Oil-filled operational equipment as defined in Part 112.2 is only subject to the general secondary containment provision, and the owner or operator may use the flexibility of active containment measures. However, active containment measures may be risky because they require the ability to detect a discharge, and these measures must be implemented effectively and in a timely manner to prevent oil from reaching navigable waters and adjoining shorelines, as required by 112.7(a)(3)(iii) and (c).
As provided in 112.7(k), owners and operators of facilities with eligible oil-filled operational equipment have the option to prepare an Oil Spill Contingency Plan and a written commitment of manpower, equipment, and materials to expeditiously control and remove any oil discharged that may be harmful, in lieu of general secondary containment, without having to make an individual impracticability determination as required in 112.7(d).
Pursuant to 112.7(d), if secondary containment is impracticable for any area where secondary containment requirements apply, facility owners or operators must clearly explain in the Spill Prevention, Control, and Countermeasure (SPCC) Plan why such secondary containment is impracticable and implement additional requirements. The additional requirements are:
- Periodic integrity testing of bulk storage containers;
- Periodic integrity testing and leak testing of the valves and piping associated with bulk storage containers;
- An Oil Spill Contingency Plan prepared in accordance with the provisions of Part 109, unless the facility has submitted a Facility Response Plan (FRP) under 112.20; and
- A written commitment of manpower, equipment, and materials required to expeditiously control and remove any quantity of oil discharged that may be harmful.
Loading/Unloading areas
- Any loading/unloading area with the potential for an oil discharge is subject to the general secondary containment provision. Secondary containment may be of active or passive design.
A loading and unloading area is a transfer area, which is any area of a facility where oil is transferred between bulk storage containers and tank trucks or railroad cars.
All areas with the potential for a discharge as described in Part 112.1(b) are subject to the general secondary containment provision, 112.7(c). These areas may include loading/unloading areas (also referred to as transfer areas), piping, mobile refuelers, and other areas of a facility where oil is present. A transfer operation is one in which oil is moved from or into some form of transportation, storage, equipment, or other device, into or from some other or similar form of transportation, such as a pipeline, truck, tank car, or other storage, equipment, or device.
Loading or unloading areas where oil is transferred but no loading/unloading rack (as defined in 112.2) is present are subject to 112.7(c), and thus appropriate secondary containment and/or diversionary structures to prevent a discharge to navigable waters or adjoining shorelines are required. The spill prevention, control, and countermeasure (SPCC) rule (Part 112 Subparts A to C) does not require specifically sized containment for transfer areas; however, containment capacity must be based on the typical failure mode and most likely quantity of oil that would be discharged.
The general secondary containment requirement at 112.7(c) applies to both loading and unloading areas. Examples of activities that occur within transfer areas include, but are not limited to:
- Unloading oil from a truck to a heating oil tank,
- Loading oil into a vehicle from a dispenser, and
- Transferring crude oil from an oil production tank battery into tank trucks.
Secondary containment may be either active or passive in design and take into consideration the specific features of the facility and operation or activity. Specific features of different loading/unloading operations include the hardware, procedures, and personnel who are able to take action to limit the volume of a discharge. The determination of adequate general secondary containment volume must consider the typical failure mode and the most likely quantity of oil that would discharge as a result of that failure:
- Typical failure mode: The source and the mechanism of failure must be identified. These could include a failed hose connection; improper transfer equipment connection or disconnection; pump, valve, flange or pipe fitting leak; or overfill of a container. Determining the typical failure mode would be based on the type of transfer operation, equipment, and procedures, facility experience and spill history, potential for human error, etc.
- Most likely quantity of oil discharged: This factor is based on the reasonably expected rate of discharge and duration of the discharge.
- The reasonably expected rate of discharge: This factor will depend on the typical mode of failure. It may be equal to the maximum rate of transfer, e.g., when an improperly connected transfer hose connection separates, or the expected leakage rate, e.g., from a pump, pipe flange, pipe fitting, or hose valve.
- The ability to detect and react to the discharge: This factor will depend on the availability of monitoring instrumentation for prompt detection of a discharge and/or the proximity of personnel to detect and respond to the discharge. The ability to detect a discharge is critical for the implementation of active containment measures.
- The reasonably expected duration of the discharge: This factor may depend on the accessibility of manual or automatic shutdown mechanisms, the proximity of qualified personnel to the operation, and other factors that may limit the duration of a discharge.
After identifying the typical failure mode for each transfer area and the most likely quantity of oil that would be discharged, the facility owner or operator can determine the appropriate type of secondary containment (i.e., active or passive).
To determine if active containment measures are appropriate to address the most likely discharge quantity, the owner or operator must determine the time it would take a discharge to impact navigable waters or adjoining shorelines. This factor will depend on the proximity to waterways and storm drains, and the slope of the ground surface between the loading area and the waterway or drain. The SPCC Plan must describe the type of secondary containment and, for active containment measures, clearly outline the procedures, equipment, and personnel necessary to implement this containment strategy.
A number of other factors may affect the appropriate volume for secondary containment at loading and unloading areas, such as the variable rate of transfer; the ability to control a discharge from a breached container, if such a breach is reasonably expected to occur; the availability of personnel in close proximity to the operations and the necessary time to respond; the presence or absence of monitoring instrumentation to detect a discharge; the type and location of valving that may affect the probable time needed to stop the discharge; and the presence or absence of automatic valve actuators. These are a few examples of the factors that a professional engineer (PE) may want to consider when reviewing the adequacy of secondary containment systems at a facility.
Secondary containment structures, such as dikes or berms, may not be appropriate in areas where vehicles continuously need access; however, curbing, drainage systems, active containment measures, or a combination of these systems can adequately fulfill the secondary containment requirements of 112.7(c).
A facility owner or operator may implement methods for secondary containment other than dikes or berms. For example, a transfer truck loading area at an onshore oil production facility may be designed to drain discharges away to a topographically lower area using a crescent or eyebrow-shaped berm. In certain situations, secondary containment at transfer areas may be impracticable due to geographic limitations, fire codes, etc. In these cases, owners or operators may determine that secondary containment is impracticable in accordance with 112.7(d) and must clearly explain the reasons why secondary containment is not practicable and comply with the alternative regulatory requirements.
Loading/Unloading racks
- Loading/Unloading rack means a fixed structure (such as a platform, gangway) necessary for loading or unloading a tank truck or tank car.
- Section 112.7(h) applies to areas at regulated facilities where traditional loading/unloading racks for tank cars and tank trucks are located.
Loading/Unloading rack means a fixed structure (such as a platform, gangway) necessary for loading or unloading a tank truck or tank car. A loading/unloading rack includes a loading or unloading arm and may include any combination of the following: piping assemblages, valves, pumps, shut-off devices, overfill sensors, or personnel safety devices. If the equipment does not include a hose without a loading or unloading arm, then the equipment is not a loading/unloading rack, by definition.
Part 112.7(h) applies to areas at regulated facilities where traditional loading/unloading racks for tank cars and tank trucks are located. Environmental Protection Agency (EPA) inspectors may evaluate compliance with the requirements of 112.7(h) for equipment that meets the definition of “loading/unloading rack” as found in 112.2.
A loading/unloading arm is a critical component of a loading/unloading rack. A loading/unloading arm is typically a movable piping assembly that may include fixed piping or a combination of fixed and flexible piping, typically with at least one swivel joint (that is, at least two articulated parts that are connected in such a way that relative movement is feasible to transfer product via top or bottom loading/unloading to a tank truck or tank car). However, certain loading/unloading arm configurations present at loading racks may include a loading/unloading arm that is a combination of flexible piping (hoses) and rigid piping without a swivel joint. In this case, a swivel joint is not present on the loading arm because flexible piping is attached directly to the rigid piping of the loading arm and the flexible hose provides the movement needed to conduct loading or unloading operations in lieu of the swivel joint.
In developing the definition in 112.2, EPA considered existing definitions of the term “loading rack” and related terms, as found in industry, federal, state, or international references, and reviewed various types of equipment considered components of loading racks. This definition does not include simple loading or unloading configurations, but rather only includes the associated equipment and structures associated with loading/unloading arms as part of a rack. Equipment present at a loading/unloading area where a pipe stand connects to a tank car or tank truck via a flexible hose is not a loading/unloading rack because there is no loading or unloading arm. Because some top and bottom loading/unloading racks are made up of a combination of steel loading arms connected by flexible hosing, the presence of flexible hoses on oil transfer equipment should not be used as an indicator of whether the equipment meets the definition of loading/unloading rack.
Subparagraph 112.7(h)(1) requires a sized secondary containment system, which means the containment must hold at least the maximum capacity of any single compartment of a tank car or tank truck loaded or unloaded at the facility.
However, the spill prevention, control, and countermeasure (SPCC) rule does not require that secondary containment for loading/unloading racks be designed to include freeboard for precipitation. When drainage from the areas surrounding a loading/unloading rack do not flow into a catchment basin or treatment facility designed to handle discharges, facility owners and operators must use a quick drainage system (112.7(h)(1)). A “quick drainage system” is a device that drains oil away from the loading/unloading area to some means of secondary containment or returns the oil to the facility.
Loading and unloading activities that take place beyond the rack area are not subject to the requirements of 112.7(h), but are subject, where applicable, to the general secondary containment requirements of 112.7(c). Loading/unloading racks can be located at any type of facility; however, loading/unloading racks are not typically found at farms or oil production facilities. Oil transfers to or from oil storage containers at farms and oil production facilities where no loading rack is present are subject to the general secondary containment requirement.
For example, a facility may have two separate and distinct areas for transfer activities. One is a tank truck unloading area and the other includes a tank truck loading rack. The unloading area contains no rack structure, so the secondary containment requirements of 112.7(c) apply. The requirements of 112.7(h) apply to the area surrounding the loading rack. As highlighted by this example, the presence of a loading rack at one location of a facility does not subject other loading or unloading areas in a separate part of the facility to the requirements of 112.7(h).
However, if a facility has a tank truck loading rack and unloading area that are co-located, the more stringent secondary containment provision applies; therefore, the area is subject to the sized secondary containment requirements of 112.7(h)(1).
In certain situations, the sized secondary containment requirements of 112.7(h)(1) for loading/unloading racks may be impracticable due to geographic limitations, fire codes, etc. In these cases, the owner or operator may determine that secondary containment is impracticable as provided in 112.7(d). Under that provision, the SPCC Plan must clearly explain the reasons why secondary containment is not practicable and comply with the alternative regulatory requirements.
Piping
- Because oil discharges from piping are common, all piping, including buried piping, must comply with general secondary containment requirements.
- If an impracticability determination is made, the SPCC Plan must clearly describe why secondary containment measures are impracticable and how alternative measures will be implemented.
Discharge reports from the Emergency Response Notification System (ERNS) suggest that discharges from valves, piping, flowlines, and appurtenances are much more common than catastrophic tank failure or discharges from tanks. To prevent a discharge to navigable waters or adjoining shorelines, the spill prevention, control, and countermeasure (SPCC) rule requires that all piping (including buried piping) comply with the general secondary containment requirements contained in Part 112.7(c). This means the owner/operator of an oil production facility may either, comply with the general secondary containment requirements of 112.7(c) for flowlines and intra-facility gathering lines or develop a contingency plan and a written commitment of manpower, equipment, and materials in accordance with 112.9(d)(3).
In many cases, secondary containment for piping will be possible. Nevertheless, 112.7(c) provides flexibility in the method of secondary containment. (Active containment measures including land-based response capability, sorbent materials, drainage systems, and other equipment are acceptable.) Paragraph 112.7(c) does not prescribe a specific containment size for piping; however, the secondary containment must be designed to address a typical failure mode for the piping and most likely quantity of oil discharged. The SPCC Plan should describe the expected sources of a discharge from piping systems, maximum flow rate, duration of a discharge, and discharge detection capability at the facility taking into consideration the specific features of the facility and operation. Calculations for each piping system may not be practical at large facilities due to the large number and complexity of the piping; instead, more general assumptions specific to the conditions at the individual facility may be appropriate as long as they are well documented in the plan.
The Environmental Protection Agency (EPA) inspector may ensure that the secondary containment method for piping is described in the SPCC Plan and that the professional engineer (PE) has certified that the method is appropriate for the facility according to good engineering practice.
In the case of a qualified facility, the owner or operator would certify that the method is appropriate for the facility in accordance with accepted and sound industry practices and standards. If active containment measures are selected, the facility personnel should be able to demonstrate that they can identify a discharge in a timely manner (e.g., a leak detection method) and effectively deploy these measures to contain a potential spill before it reaches navigable waters or adjoining shorelines.
Secondary containment may not always be practicable for piping. If secondary containment is not practicable, then the facility owner or operator may make an impracticability determination and comply with the alternative regulatory requirements described in 112.7(d), which includes developing an Oil Spill Contingency Plan. In order for a contingency plan to be effective, discharges must be detected in a timely manner. For example, good engineering practice may require that unattended facilities where secondary containment is impracticable be inspected more frequently than would be required at a typical facility where secondary containment is provided.
The SPCC Plan may include other procedures, testing, and/or equipment to aid in the timely implementation of a contingency plan and/or overall oil spill prevention. This may include, but is not limited to, aggressive pipe integrity management/testing procedures, leak detection equipment, and enhanced corrosion protection. If it is not feasible to effectively and reliably implement a contingency plan and the facility does not meet the applicability criteria under the Facility Response Plan (FRP) requirements in 112.20, then facility owners or operators must determine how to comply with the applicable secondary containment requirements in 112.7(c).