What went wrong? The trench plate was placed over a three-foot deep trench adjacent to other plates and shifted while unattended, falling into the trench with approximately 12-inches of the plate projecting above the ground surface.  The plate was not pinned or “locked” by welding to other plates or stabilized with an asphalt perimeter. 

What did we learn?  Trench plates move.  Depending on your application, some plates are texturized creating a rough top surface and more traction for pedestrians and vehicles.  Other plates are slick-top.  In either case, vehicles can move a plate if the car accelerates atop the plate and it is not locked in place. 

Mitigations.  All plates placed by Stratus or our subs should be part or the WRA, taking into consideration that “plates move”.  The traffic level and type are key contributors.  All plates should, at minimum, be stabilized with asphalt around the perimeter of the plate if the plate will be unattended or in high pedestrian traffic locations (trip minimization).  Adjoining plates should be placed tightly together to assist in “locking” their movement.  Plates in high traffic areas or on slopes (regardless of angle) should also be tack welded and pinned to the ground. 

More to follow in our monthly meeting.

The following is an example of a Stop Work event that was required because a line was discovered – even with all the controls in place.

Scope and Preparation: The contractor was onsite to oversee the in-place abandonment of underground storage tanks (USTs). Prior to the ground disturbance activities, both public and private utility locating service activities had been completed  for the required sweep zone of the excavation areas (30-feet minimum).

Stop Work: During excavation, a ½” copper water line was encountered within the UST pit that had not been identified by either of the utility locate services. When the line was identified, Contractor personnel onsite called a Stop Work and the project manager (PM) was notified.

Assessing Risk: The line appeared to be abandoned and associated with the USTs, given its location (crossing the pit between fill ports). The Stop Work remained in effect until the private utility service could conduct additional locating for this line, which was carried out the next morning. The utility locate determined that the line was no longer connected to any above or below ground structures and was in fact, abandoned.

Resume Work: Once confirmed, the Stop Work was ended, and the excavation resumed onsite without further incident.

Learnings: It was determined by the utility locating service that the copper line was not identified by either of the previous locates due to the line’s location over the USTs. The public locate did not identify it because it did not terminate at the surface and the private locate (which had been conducted with a ground penetrating radar and EM) did not identify it because it had been masked by the signals received from the USTs.

Remember: Good planning and communication up-front is key to safe work but it doesn’t always end there. Be prepared to reassess and update communications as conditions warrant.

The answers to these questions will vary with each job site and type of equipment used. Everyone knows and agrees that inspections are necessary before equipment use, but it is also important to know that the inspector is qualified, knows what to look for, and is inspecting the equipment to the appropriate level of detail for the intended use.

Here are a few pictures that demonstrate how relying on a simple tag attached to the equipment and not inspecting the equipment yourself before use may be inviting tragedy or trouble.

The picture below clearly shows the equipment was inspected by Joe (likely from the rental company) and passed inspection.

Do you trust it? No.  You do your own inspection and guess what you find?

These are the welds that hold the man basket to the boom.  This is a simple discovery that may have saved your life (and/or others lives).

Remember, inspect (and document) before each use.

Description of Incident: An employee of Honeywell subcontractor United Mechanical was working in an aerial lift installing pipe hangers. The lift was positioned over a metal grate. The grate gave way allowing a wheel of the lift to drop about 3 feet into the trench. This threw the employee out of the cage. He was saved from a fall of over 30 feet by wearing his fall protection. When he was ejected from the work platform, the employee struck his head on ceiling structures and broke his nose. Another lift was used to rescue him and he was taken to a health care facility for treatment.

Immediate Causes: Employees head struck ceiling structures

Root Causes: Inadequate floor grate design/installation – support was inadequate at the corners and failed under the weight of the aerial lift. A concrete lip provides support for the grate in all the straight runs, but not at the corners.

HSE Management System Core Process Failures: Operational Controls: Inadequate floor grate design/installation

Corrective Actions:

• Mark floor hazards and avoid driving equipment over floor grates where possible
• Require use of metal sheets over grates if driving over them is not avoidable
• Reinforce use of fall protection on aerial lifts – it probably saved this man’s life