Secondary containment

Scope

See the secondary containment regulations (listed in the Regulatory Citations section below) for specifics regarding applicability and scope. Secondary containment regulations may:

• Call for passive secondary containment;
• Allow for passive or active secondary containment; and/or
• Allow for alternatives to secondary containment to prevent released material from reaching waterbodies.

Secondary containment regulations could also, for example, require:

• Specific sizing (volume) for either a worst-case discharge (e.g., construction of secondary containment sized to contain a discharge from the largest container) or a typical discharge incident (based on a most-likely scenario);
• Design specifications to address passive or active measures, impermeability of containment structures, and freeboard for precipitation;
• Maintenance provisions, including inspections to ensure the designed capacity is maintained (e.g., by removing rainwater or other debris); and
• Corrective actions to ensure that inspection results are addressed.

Regulatory citations

• 29 CFR 1910.106 — Flammable liquids
• 29 CFR 1910.110 — Storage and handling of liquefied petroleum gases
• 29 CFR 1910.120 — Hazardous waste operations and emergency response
• 30 CFR 56.4430 — Storage facilities
• 30 CFR 57.4430 — Surface storage facilities
• 30 CFR 816.41 — Hydrologic-balance protection
• 40 CFR 68 — Chemical accident prevention provisions (the regulation mentions passive mitigation)
• 40 CFR 112 — Oil pollution prevention
• 40 CFR 122.26 — Storm water discharges (applicable to state NPDES programs, see 123.25) (the regulation mentions structural and non-structural control measures)
• 40 CFR 122.34 — Permit requirements for regulated small MS4 permits (the regulation mentions structural and/or non-structural best management practices (BMPs))
• 40 CFR 165.80 to .87 — Standards for pesticide containment structures
• 40 CFR 262.16 — Conditions for exemption for a small quantity generator that accumulates hazardous waste
• 40 CFR 262.17 — Conditions for exemption for a large quantity generator that accumulates hazardous waste
• 40 CFR 262.252 — Required equipment
• 40 CFR 262.253 — Testing and maintenance of equipment
• 40 CFR 262.255 — Required aisle space
• 40 CFR 262.261 — Content of contingency plan
• 40 CFR 264.175 — Containment
• 40 CFR 264.193 — Containment and detection of releases
• 40 CFR 265.193 — Containment and detection of releases
• 40 CFR 279 — Standards for the management of used oil
• 40 CFR 280 — Technical standards and corrective action requirements for owners and operators of underground storage tanks
• 40 CFR 403.8 — Pretreatment program requirements: Development and implementation by POTW
• 40 CFR 430.03 — Best management practices (BMPs) for spent pulping liquor, soap, and turpentine management, spill prevention, and control
• 40 CFR 440.148 — Best management practices (BMP)
• 40 CFR 455Appendix Table 8 — List of pollution prevention alternative practices
• 40 CFR 761.65 — Storage for disposal

Key definitions

• Double-walled tank: Essentially a tank within another tank, equipped with an interstitial (i.e., annular) space and constructed in accordance with industry standards. The inner tank serves as the primary storage container while the outer tank serves as secondary containment. The outer tank of a double-walled tank may provide adequate secondary containment for discharges resulting from leaks or ruptures of the entire capacity of the inner storage tank. Note: 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. Moreover, a double-walled tank does not provide adequate secondary containment to address transfer-related overfills from the tank vent; therefore, secondary containment measures may be necessary to contain overfills from vents associated with transfer operations.
• Freeboard: Capacity of the secondary containment meant to hold precipitation above and beyond the capacity intended for a discharge from the largest single container. Note: Whether freeboard is “sufficient” is a matter of engineering practice that may depend on local precipitation conditions, height of the containment wall, size of the tank or container, safety considerations, and frequency of the secondary containment drainage and inspection.
• Secondary containment: Temporary containment of a discharge if the primary container fails. Secondary containment gives a facility time to abate the source of the discharge and remove the accumulated chemical to prevent it from reaching waterbodies.
• Storage capacity of a container: The shell capacity of the container.

Summary of requirements

• Determine which, if any, of the federal secondary containment regulations apply to the facility. See the list of regulations in the Regulatory Citations section above. Consider the type of materials present and the nature of the onsite operations.
• If the federal secondary containment regulations apply, be sure to meet them. Consider consulting a licensed professional engineer to ensure the secondary containment not only meets the regulations but follows good engineering practice and industry standards.
• If the storage container is located inside a building, the facility might be allowed to take into consideration the ability of the building walls and/or drainage systems to serve as secondary containment. Note:
  • 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) facility), or otherwise directly into a waterbody may be a violation or problem, as it becomes a conduit for a discharge to reach navigable waters or adjoining shorelines.
  • Any secondary 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.
  • Any doorways, windows, or other building openings must not permit a discharge to flow out of the building.
  • When secondary containment is provided inside a building, freeboard calculations for precipitation are typically not applicable.
• Where federal secondary containment regulations do not apply, but the facility has the reasonable risk of a discharge to waterbodies:
  • Consider secondary containment or alternative modes of protection to prevent and contain oil discharges and consult with a professional engineer.
  • Determine whether the state environmental or local fire/building codes require secondary containment.
  • Determine if industry consensus standards that include secondary containment requirements are adopted by state or local codes. Look at standards from the National Fire Protection Association (NFPA) and International Fire Code (IFC), for example.
• If a facility has outdoor passive secondary containment, when rainwater accumulates in the containment system, check the rainwater for any chemical discharge. If no chemical is present, the rainwater can be drained from the system. However, if there is chemical in the water, this water will need to be removed and disposed of properly. If this happens, check with your state extension agent or your chemical supplier to get help.
• Whether a facility has secondary containment or not, if the facility suffers a reportable spill or release, the facility must report it according to federal, state, and local laws, regulations, and permits. Some, but not all, spills may be reportable even if they are contained in secondary containment.