• Containers must be protected with an overfill prevention system to avoid accidental oil spills.

Regulations 112.8(c)(8) and 112.12(c)(8) require that each container installation is engineered to avoid discharges during filling activities. The regulation offers the following options:

• High liquid level alarms with an audible or visual signal at a constantly attended operation or surveillance station. In smaller facilities an audible air vent may suffice.
• High liquid level pump cutoff devices set to stop flow at a predetermined container content level.
• Direct audible or code signal communication between the container gauger and the pumping station.
• A fast response system for determining the liquid level of each bulk storage container, such as digital computers, telepulse, or direct vision gauges. If this alternative is used, a person must be present to monitor gauges and the overall filling of bulk storage containers.

The selection of an overfill prevention system should be based on good engineering practice, considering methods that are appropriate for the types of activities and circumstances. Regular tests of liquid level sensing devices to ensure proper operation should be conducted.

While an audible/visual alarm or fast-response system may be appropriate for a large, stationary storage tank, a simpler overfill prevention procedure may be appropriate for a small container (e.g., relatively small containers that can be readily monitored) when the filling procedure is documented in the Spill Prevention, Control, and Countermeasure (SPCC) Plan. A procedure for smaller containers that ensures communication between the container gauger and the pumper, is in accordance with 112.8(c)(8)(iii) and 112.12(c)(8)(iii) and therefore does not require an environmental equivalence determination.

The procedure must be adequate to prevent a discharge by ensuring communication between the container gauger and the pumper. The development of this procedure should consider factors such as the container size; inventory control procedures; filling rate; ability of the person performing the filling operation to continuously monitor product level in the container; reaction time; capacity of the secondary containment and/or catchment basin; and proximity of the tank to floor drains, sumps, and other means through which oil could escape. Personnel should be able to demonstrate an understanding of the procedures and proper field implementation.

As part of the description, the plan preparer may reference other facility documents in the SPCC Plan that discuss relevant established best management practices (BMPs), pollution prevention training, and/or procedures in more detail, rather than restating this information in the SPCC Plan. Additional supporting documentation should be onsite and available for review during an inspection.

For example, a filling procedure for a small container may involve:

• Verifying that the container has sufficient free capacity (i.e., ullage of the container) for the transfer,
• Visually monitoring the product level throughout the transfer operation, and
• Posting the detailed written procedure described in the SPCC Plan next to the container/fill pipe.

Many facilities have smaller storage containers such as 55-gallon drums, intermediate bulk containers (IBCs) and totes that are never filled at the facility. Since these containers are never filled, the overfill requirements do not apply and there is no need to document environmental equivalence deviations for these containers.

Where a facility owner or operator chooses to deviate from the overfill prevention provisions by using an alternative measure that provides environmentally equivalent protection, the SPCC Plan must state the reasons for nonconformance and describe the alternative measure in detail, including how it achieves equivalent environmental protection when implemented (112.7(a)(2)).

Preventing container overfills In order to prevent container overfills, owner/operators should consider the following:

• Training individuals involved in the transfer operations;
• Communicating facility oil transfer procedures to personnel;
• Ensuring transfer operations are appropriately monitored;
• Ensuring tank gages and overfill alarms are operational, calibrated, and routinely tested;
• Verifying that the container has sufficient available capacity;
• Monitoring the product level throughout the operation; and
• Providing response equipment that is easily accessible from the transfer location.