Confined Space Safety Best Practices for Decentralized Wastewater Systems

ByLaura Schultz

What do manholes, silos, vaults, pits, tanks, tunnels, ductwork, and hoppers have in common? 

They are all examples of what the Occupational Safety and Health Administration (OSHA) defines as confined spaces, or workplace areas that are not designed for human presence, but are large enough for workers to enter and perform necessary tasks. Such spaces are also all incredibly dangerous for these workers if proper safety precautions are not followed. Possible dangers in confined spaces include hazardous atmospheres, materials that could engulf an entrant, possible collapse of the space, walls that converge inward/floors that slope downward into a smaller area, or other common safety hazards like exposed wires, heat, or dangerous machinery.

Specifically, the primary danger in confined spaces is usually oxygen availability — The air we breathe in unconfined spaces has about 21 percent oxygen, but will run lower in a confined space. A reduction to 12 to 16 percent oxygen can cause pulse & respiration issues and loss of coordination, while 6 to 10 percent oxygen present can lead to nausea, vomiting, loss of consciousness, or death.

In the decentralized wastewater industry, the main confined space an installer or maintenance provider will enter is, of course, a septic tank. Not every possible confined space danger listed above applies to septic tanks, but many do. As such, it is critically important to take every possible precaution and know how to remain safe if your jobs ever take you inside a tank. 

Personal Protection Equipment

A worker entering a confined space must be outfitted appropriately. There’s a wide assortment of personal protection equipment (PPE) that can be worn to keep safe in a confined space. Respirators, gloves, and safety harnesses are standard items, but air-purifiers, safety glasses/goggles, earmuffs or plugs, and protective clothing such as coveralls, hard hats, and boots are also highly recommended. 

General Confined Space Safety Precautions

Here’s a list of standard safety precautions for all confined spaces, according to the safety technology company Safety Culture:

  • Make sure all workers entering confined spaces are properly trained and certified.
  • Perform hazard assessments and inspections ahead of entry.
  • Monitor the air quality and available ventilation.
  • Have another worker on standby outside the space at all times, and ensure there is a secure line of communication in and out of the space.
  • When applicable to your equipment, implement lockout/tagout procedures.
  • Have comprehensive emergency response and rescue plans/procedures in place, and require that all workers be aware of them.

Septic Specific Safety Precautions

Here’s a list of safety advisories specific to working with septic tanks from the South Carolina Department of Environmental Services:

  • Don’t lean over an open septic tank or stick your head inside to examine it without properly suiting up and preparing to enter it.
  • Do not enter the tank unless you are wearing the necessary special PPE, including a self-contained breathing apparatus/respirator.
  • If someone else falls into or becomes trapped in the tank while working, do not go in to retrieve them, unless you have a respirator. Call for emergency assistance and use fans to blow fresh air into the tank.
  • Never work alone in or around a septic tank — and have someone on standby if at all possible.
  • Make sure the covers to access ports are secure and will not collapse or be moved to expose the tank opening.
    • In particular, abandoned septic tanks are likely to have unsafe covers that could cause a worker (or any other person or animal going over it) to fall in if the cover collapses. 
  • Rope off the work area and any other dangerous sites.

OSHA Standards and Requirements

The OSHA standard for confined spaces is 1910.146, and can be read in full here. You can also find other OSHA standards that touch on confined spaces in other areas here. Be aware that OSHA uses the term “permit-required confined space,” or permit space, to refer to spaces that have one or more of the hazards already described. A non-permit required confined space is one that does not contain those hazards, and are unlikely to cause severe harm or death. (That said, it is still important to take safety precautions in them — Check out Safety Culture’s guidelines and checklist on how to keep these spaces free of hazards, if you’re ever working with non-permit spaces). 

Rescue Plans

OSHA also has requirements on what a confined space rescue plan must contain. Find some highlights of the requirements listed below, and find the full list at Safety Culture or within the OSHA standard.

  • Your plan’s procedures should cover summoning emergency services, rescuing entrants of permit spaces, providing emergency services to rescued entrants, and preventing unauthorized personnel from attempting rescue.
  • Evaluate prospective rescue services ahead of time, and inform the one you select about the specific hazards of rescue from confined spaces (and septic tanks).
  • Train employees in the PPE they need, and how to perform their assigned rescue duties and basic first-aid/CPR. Have employees practice rescue procedures and duties at least once every year. 

Confined Space Training

One great option to ensure that you and any employees you might have are fully prepared for confined space work is to take a confined space safety training course. You can find a number of options with Google, including virtual courses, training providers that will come to you, or even pre-scheduled in-person classes. DecentralizedWastewater.org will list any such classes with defined schedules in our Events Calendar as we find them offered by our monitored training providers. Here are some examples of confined space training that is available, though we are not endorsing any particular course or program:

Sources and Other Resources