713 Confined Space Program

Appendix E to § 1910.146
Sewer System Entry

Sewer entry differs in three important ways from other permit entries:

• • There is rarely a way to fully isolate the space to be entered.
• • Because isolation is not complete, the atmosphere can suddenly and unpredictably become deadly due to toxic, flammable, or explosive hazards beyond the entrant’s or employer’s control.
• • Experienced sewer workers are very familiar with entry and work procedures in permit spaces due to frequent entry. Unlike other jobs where permit entry is rare, for sewer workers it is common.

(1) Adherence to procedure. The employer must choose only employees who are fully trained in sewer entry procedures and who follow them exactly when entering sewers.

(2) Atmospheric monitoring. Entrants must be trained to use, and equipped with, atmospheric monitors that have both alarms and visual displays. These monitors must alarm when:

• • Oxygen is below 19.5%;
• • Flammable gas or vapor is at 10% or more of the lower flammable limit (LFL);
• • Hydrogen sulfide is at or above 10 ppm, or carbon monoxide is at or above 35 ppm, measured over an 8-hour time-weighted average.

Monitors must be calibrated following the manufacturer’s instructions. Oxygen/broad range sensors are best when the exact contaminants are unknown. These sensors give general readings of flammables but do not show exact levels of individual chemicals. When contaminants are known, substance-specific devices must be used for accurate readings. These readings help the employer choose safety measures like ventilation or personal protective gear.

Because sewer environments can suddenly change, substance-specific devices might not detect all dangerous changes. OSHA says the above guidance is useful, but each employer must decide what testing tools to use based on their own knowledge and experience with their sewer systems.

The chosen testing tool must be carried and used by the entrant to test the air in their current location and in the direction they are moving. If multiple workers are in the same spot, one device used by the lead worker is acceptable.

(3) Surge flow and flooding. Sewer crews must maintain contact, when possible, with local weather services and emergency responders. This allows them to delay or stop work and remove entrants when sewers may flood due to rain, firefighting, or emergency spills of hazardous materials.

(4) Special Equipment. Working in large sewers may require special tools. These include:

• • Atmospheric monitors with alarms;
• • Escape self-contained breathing apparatus (ESCBA) with at least a 10-minute air supply or other approved self-rescuer;
• • Waterproof flashlights;
• • Boats, rafts, radios, and rope stand-offs to help maneuver around bends and corners.

All equipment must be used to make sure entry permit requirements are met before starting the entry.

• 1910.146(c)
  General requirements.
• 1910.146(c)(1)

  The employer must evaluate the workplace to determine if any spaces are permit-required confined spaces.

• Note:

  Proper use of the decision flow chart in appendix A to § 1910.146 helps meet this requirement.

• 1910.146(c)(2)

  If permit spaces exist, the employer must inform exposed employees by posting danger signs or another effective method.

• Note:

  A sign that says "DANGER - PERMIT-REQUIRED CONFINED SPACE, DO NOT ENTER" or similar wording is acceptable.

• 1910.146(c)(3)

  If employees will not enter permit spaces, the employer must stop them from entering and follow paragraphs (c)(1), (c)(2), (c)(6), and (c)(8).

• 1910.146(c)(4)

  If employees will enter permit spaces, the employer must create and follow a written program. This must be available for inspection.

• 1910.146(c)(5)

  An employer may use alternate procedures described in (c)(5)(ii) if the conditions in (c)(5)(i) are met.

  • 1910.146(c)(5)(i)

    Employers do not need to follow (d) through (f) and (h) through (k), if:

    • (A) The only hazard is a hazardous atmosphere.
    • (B) Forced air ventilation alone keeps the space safe.
    • (C) Monitoring and inspection data support (A) and (B).
    • (D) If entry is needed for data, follow (d) through (k).
    • (E) Proof for (A), (B), and (C) must be documented and shared with employees or their reps.
    • (F) Entry must follow (c)(5)(ii).
  • Note:

    See (c)(7) for reclassifying a space after all hazards are removed.

  • 1910.146(c)(5)(ii)

    These apply if the permit space meets (c)(5)(i):

    • (A) Remove entrance covers only after removing unsafe conditions.
    • (B) Guard the opening with a barrier to prevent falls or falling objects.
    • (C) Test air for oxygen, flammable gases, and toxic contaminants. Let employees or reps observe.
    • (D) No hazardous atmosphere allowed when employees are inside.
    • (E) Use forced air ventilation:
      • (1) Do not enter until air is safe.
      • (2) Direct ventilation to where employees are and keep it running.
      • (3) Air must come from a clean source and not add hazards.
    • (F) Test the air regularly. Let employees or reps observe.
    • (G) If hazardous air is found:
      • (1) Leave the space immediately.
      • (2) Evaluate the cause.
      • (3) Fix the issue before going back in.
    • (H) Verify space is safe with a written certification showing date, location, and signature. Share this before entry.
• 1910.146(c)(6)

  If a non-permit space changes and becomes more hazardous, it must be re-evaluated and possibly reclassified as a permit-required space.

• 1910.146(c)(8)

  If a host employer hires a contractor for permit space work, the host must:

  • (i) Tell the contractor about the permit spaces and entry program rules.
  • (ii) Share known hazards and the employer's experience with the space.
  • (iii) Tell the contractor about any safety steps taken for employee protection.
  • (iv) Coordinate entry if both the host and contractor workers are involved.
  • (v) Debrief the contractor after work about the entry program and any hazards faced or caused.