The Ins & Outs of Confined Spaces in the Sewer Rehabilitation Industry

An upward shot of the inside of a manhole, showing a ladder and an extended retrieval winch

Archview Services would like to thank Dennis Pivin, CSP and Director of Health, Safety, and Environmental at NASSCO for writing this article and giving us permission to publish it on our website.

Understanding the hidden dangers and the critical importance of proper preparedness in confined space are vital to a safe work site. This includes, but is not limited to, sewer structure rehabilitation, manhole entry, and infrastructure inspection processes. Any incidents or accidents during confined space entry are of particular concern to the health and safety of workers due to the hazards they pose to the entrant as well as the attendant.

What Is a Confined Space?

A wall with a sign that says "Danger. Confined Space. Entry by Permit Only."

To begin, we need to understand the definition of confined space. According to the Occupational Safety and Health Administration (OSHA), a permit-required confined space is a confined space that is generally recognized as a space that:

  • Has limited or restricted means of entry or egress. 
  • Is large enough for a person to enter to perform work.
  • Is not designed for continuous occupancy.
  • Contains or has the potential to contain a hazardous atmosphere.
  • Is designed in a manner that could cause an entrant to be trapped.

If you look at the guidelines and apply them to all sewer and culvert structure rehabilitation, these entries will be considered permit-required confined space entry due to the possibility of one or all of the conditions above existing at any given time.

One of the primary tasks that should be completed prior to working in sewer structure access points is that each employer must have a written program.

There are a few critical items that an employer should consider, including evaluating confined spaces for hazards, identifying what your company will consider confined spaces (sewer structure access points, pits, culverts, sanitary and storm manholes, etc.), establishing policies to control the identified hazards, and setting up confined space procedures for entering the space.

Confined Space Entry Protection

A confined space entry worker holds a manual and gas detection monitor

Now, let’s look at some key elements of the standard that are designed to protect workers from unknown hazards and potential injury while working in confined spaces. These include completion of a confined space permit, continuous air monitoring, continuous ventilation, entrants wearing a properly fitted harness and having entrants attached to a winch retrieval system and self-retracting lifeline.

Listed below is a brief breakdown of these critical components:

1) Completing a Confined Space Permit

Prior to entering the confined space, a Confined Space permit must be filled out completely.

  • The employer determines the employees qualified for these roles.
  • Key elements required on the Confined Space permit include, but are not limited to the following: date and authorized duration of the entry, name of the authorized attendant, identifying authorized entrants inside the permit space (i.e. rosters or tracking systems), logging air monitoring results at regular intervals as determined by the employer, and identifying hazards associated with the confined space entry.
  • Upon completion of the confined space entry, the permit must be signed and closed to ensure completion by the entry supervisor.

2) Continuous Air Monitoring or Atmospheric Testing

  • Before an employee enters the space, the entire internal atmosphere shall be tested. When conducting air monitoring of a confined space, be sure to test all levels of the confined space (top, middle, and bottom). Gases in confined spaces have different densities and may be found in different locations within the confined space. Typically, the sewer rehabilitation industry will include sensors for the following: Oxygen, LEL, Hydrogen Sulfide, and Carbon Monoxide.
  • The atmosphere within the confined space must be continuously monitored.

3) Continuous Ventilation

  • After the initial air sampling has occurred, start the ventilation process, but always continue air monitoring.
  • Ventilation of the confined space should be continuous.

4) Entrants Wearing Properly Fitted Harnesses

  • When entering a confined space, the entrant must wear a harness for both retrieval and fall protection.
  • Harnesses should be inspected before use and always follow the harness manufacturers’ specification for all training and inspection protocols.

5) Entrants Must Be Attached to a Retrieval Winch & Fall Protection Device

  • When the entrant is being lowered into a sewer structure access point, the entrant must be attached to a Self-Retracting Lifeline (SRL) to prevent a fall.
  • The entrant must remain attached to this system the entire time the worker is in the confined space.

Confined Space Training

Lastly, all confined space workers must be trained per the OSHA 1926 Construction Confined Space Standard. Employers must train workers involved in permit-required confined space operations so that they can perform their duties safely and understand the hazards in permit spaces and the methods used to isolate, control, or protect workers.

To have an effective training program for Confined Space, the company should cover all company confined space procedures, use and handling of confined space equipment, review company policies on emergency response, how to identify confined space hazards, proper use of air monitoring equipment, proper use of ventilation systems, and how to properly complete the confined space permit.

The OSHA standard provides the user with the information and tools needed to successfully implement a confined space program. In review, a compliant program involves understanding of what is a confined space in the workplace, having a written assessment of the hazards that may be present and listed on the confined space permit, the systems to be used to minotaur for and eliminate the hazards (air monitoring, ventilation, retrieval systems, fall protection, hazardous energy control), employee training on the use all of the systems required by the employer and, lastly, having procedures for responding to an emergency.

For more information on this topic and many others, please visit