• Tanks, vaults, vacuum trucks, elevated tanks, compressed gas cylinders, and ponds and lagoons all require special precautions to handle them and their contents safely.
• A confined space permit might be required before entering a tank or vault.

Sometimes containers present additional hazards due to their size, shape, location, or pressure. The container types covered below require extra precautions in addition to the general procedures for handling containers.

Tanks and vaults

It’s common to see tanks and vaults at hazardous waste cleanup sites. Note that excess pressure can build up inside a tank or vault. For protection from contaminants that may release when a container is opened, a deflecting shield should be placed between the employee opening the container and the opening.

Once the tank or vault is opened, manholes or access points should always be guarded to ensure no personnel inadvertently fall into the container. The contents should be identified using analysis of sample results, and the container should be characterized. If these results show the contents are safe to move, it may be possible to vacuum the waste into a vacuum truck and have it transported to a treatment, storage, and disposal (TSD) facility.

The tank or vault should be emptied and decontaminated before disposal.

It’s important to know that tanks and vaults are typical examples of confined spaces because they are often large enough to enter, have limited means of entry or exit, and are not designed for continuous occupancy.

Because tanks and vaults have the potential for dangerous atmospheres, a confined space permit may be required just to enter a tank or vault at a site. If a permit is required, the tank or vault is considered a “permit-required confined space.”

If at any time it becomes necessary to enter the tank, employees must adhere to the confined space entry procedures on the permit, along with the requirements of their employer’s written permit-required confined space program. Extra precautions needed for entering a tank or vault include:

• Disconnecting pipelines from the container;
• Obtaining air samples to verify oxygen levels and to check for flammable gases or toxic gases and vapors in the interior container atmosphere;
• Thoroughly purging, inerting, flushing, or ventilating the container to control atmospheric hazards;
• Making sure all entry workers are equipped with respiratory protection, protective clothing, a safety harness and retrieval line, and any other personal protective equipment (PPE), as needed;
• Having a trained attendant in place prior to entry;
• Establishing lifeline signals for communication between entry workers and the attendant;
• Stationing an additional employee in the area to assist the attendant if needed;
• Having the entry supervisor confirm that conditions are acceptable for entry; and
• Ensuring the attendant knows not to enter the area until additional personnel arrive.

Vacuum trucks

A vacuum truck is a tanker truck equipped with a powerful vacuum strong enough to suck sludges, slurries, and liquids into the tank on the truck. It works perfectly for emptying tanks and vaults of hazardous wastes.

Extra measures to take when working with vacuum trucks include:

• Wearing appropriate PPE and chemical protective clothing (CPC) when opening the hatch;
• Using mobile steps or suitable scaffolding if available;
• Avoiding climbing the ladder and catwalk on the vacuum tank;
• Using both hands to grip the side rails of the truck ladder while ascending or descending;
• Hoisting tools or sampling equipment only after reaching the top of the ladder;
• Sampling from the top of the vehicle if possible; and
• Standing off to the side and keeping absorbent materials close by if sampling from the drain spigot.

Elevated tanks

Elevated stationary tanks require the same precautions as vacuum trucks. However, these stationary tanks may also require fall protection, such as guardrails, safety net systems, or personal fall protection. Ladders and railings must also be maintained in a safe condition.

Compressed gas cylinders

Compressed gas cylinders can quickly become an explosion or projectile hazard if they’re damaged. When working with compressed gas cylinders, employees must:

• Handle them with extreme caution;
• Never roll, push, or pull cylinders;
• Use a cylinder cart when moving cylinders;
• Stage cylinders in cool, shaded areas;
• Keep cylinders away from any flames or sparks;
• Record identification numbers to aid in characterization; and
• Ensure cylinders are secured when moving or storing them.

Refer to the Compressed gases subject for further information.

Ponds and lagoons

Wearing PPE and CPC may make it difficult to swim, float, or tread water, creating a drowning hazard for employees near ponds and lagoons. When working around water, employees should take the following precautions:

• Work from shore if possible;
• Use lifeboats, flotation gear, or other necessary safety gear; and
• Be cautious along shorelines, keeping an eye out for solids that may float and give the appearance of a stable surface.