This month’s safety memorandum has been prepared to highlight when an excavation is considered a confined space.

OSHA defines an excavation as any man-made cut, cavity, trench, or depression in the earth's surface formed by earth removal. A trench is defined as a narrow underground excavation that is deeper than it is wide and is no wider than 15 feet.

Let us first look at the construction standard for confined spaces (1926.1200 Subpart - AA). In the scope of the standard, it clearly states exceptions. “This standard sets forth requirements for practices and procedures to protect employees engaged in construction activities at a worksite with one or more confined spaces, subject to the exceptions in paragraph (b) of this section”. Section (b)(1) states, construction work regulated by subpart P (Excavations).”
This does not mean all excavations are not confined spaces. It simply states excavation are exempt from the standard and Subpart P shall be used. Subpart P is simple and easy to follow. Summing it up:

1. Where oxygen deficiency (atmospheres containing less than 19.5 percent oxygen) or a hazardous atmosphere exists or could reasonably be expected to exist, such as in excavations in landfill areas or excavations in areas where hazardous substances are stored nearby, the atmospheres in the excavation shall be tested before employees enter excavations greater than 4 feet in depth.

2. Adequate precaution shall be taken such as providing ventilation, to prevent employee exposure to an atmosphere containing a concentration of flammable gas in excess of 20% of the lower flammable limit of the gas.

3. When controls are used that are intended to reduce the level of atmospheric contaminants to acceptable levels, testing shall be conducted as often as necessary to ensure that the atmosphere remains safe.

4. Emergency rescue equipment, such as breathing apparatus, a safety harness, and line, or a basket stretcher, shall be readily available where hazardous atmospheric conditions exist or may reasonably be expected to develop during work in an excavation. This equipment shall be attended when in use.

Steps to follow to determine whether an excavation greater than 4 feet in depth is not a confined space:

1. Oxygen levels and other atmospheric hazards are within acceptable values.

2. No surrounding areas such as landfills, active sewer lines, exhaust from running equipment such
as pumps/generators and contaminated soils exist.

3. There are adequate means of exiting the excavation (ladders, slopes, or cut steps).

4. Employees working in the excavation are protected from vehicular traffic.

If you answered yes to all the above steps, your excavation is most likely NOT a confined space. Otherwise, your excavation IS a confined space. If deemed a confined space, confined space signs shall be posted, the requirements in Subpart AA shall be followed and the DNHI Confined Space Checklist shall be initiated to determine whether the confined space is a permit-required confined space. A confined space permit shall be generated if the checklist determined a permit-required confined space exists and I should be contacted prior to entry to review procedures.

If you have any questions, please contact the safety department.

Kurt Dahl