"If we're wrong, people die." How would you handle this?

22' excavation, sloped at 63 degrees

"This is their fix; really need something back from you. You should go take a look".

This was the text I got from one of our West Michigan concrete clients.

Their team was exposed to this 22' excavation sloped at 63 degrees. I immediately looked at MIOSHA's excavation table-1 which shows which angle of slope is the maximum needed for the type of soil. In this case, the soils expert was saying it was stiff clay. MIOSHA says stiff clay can be sloped at most, 63 degrees.

"If we get this wrong, my team doesn't go home to their families"

This was the real consequence we all had to come to terms with as we met onsite to look at reality. I had been called out to this project, because a crew leader, did his job by stopping the work until he got a 3rd party safety consultants' opinion and direction on this matter.

His crew respected him for it; and so did I.

I arrived onsite early the next morning and expressed to everyone that I respect their experience and motives to get the job done and protect people. I assured them that we could do that here.

I then did three things:

1. Inspected the excavation for fissures and bulging. I didn't see any.

2. Tested the soil in different locations and elevations using a soil penetrometer. This measures the strength of the soil. It read 4.5 TSF (tons per square foot).

3. Used a smart level at different areas of the excavation to get the slope. It read between 59 and 65 degrees.

Then...

I showed everyone the numbers. And these numbers meet MIOSHA standards. But barely.

"What is our margin for error?"

"We have no margin", I said.

But the thought about telling everyone it was safe to work next to this wall of earth, made me very uncomfortable. As an experienced safety professional, I know workers who have lost their lives, and no MIOSHA standard was violated.

So I asked a simple question....

"What prevents us from getting an engineer involved?"

"Why"? Someone said.

I then read them this statement from the MIOSHA excavation standard and asked them if it applied here.

R 408.40942. Supporting systems; angle of repose; tie backs; tight sheeting; additional bracing. Rule 942. (8) Protective systems for use in excavations more

than 20 feet in depth must be designed by a registered professional engineer.

This excavation was 22 feet deep; 2 feet over the limit.

I asked the GC if the soils report and recommendation was developed by a registered professional engineer.

"No." he said.

"Well then."

"Based on the seriousness of what we are talking about here, that someone could die, I need to recommend that nobody work next to this until its sloped and shored according to a design developed by a registered professional engineer. Just as the standard says."

Why an engineer and not a qualified person?

OSHA says there are three roles needed for an excavation:

1. The competent person. This is the crew leader with experience to recognize excavation hazards and authority to stop work. This was fulfilled onsite by the concrete contractors' crew leader when he stopped work and called me out for a meeting. This is like the nurse of a hospital who can recognize the problem and take some action.

2. The qualified person. This is the person with much more specific training and experience that can solve excavation safety problems. This was the soils expert who made the recommendations initially. This is like the doctor of the hospital who prescribes treatment.

3. The engineer. This is the one that has the most expertise in the structure of engineering systems to prevent an excavation collapse. This is like the specialist of the hospital who provides specialized expertise to treat complex conditions.

If the competent person is the nurse of a hospital who takes your blood pressure, and the qualified person is the doctor who prescribes your medications, then then engineer is the cardiologist. And that is who we needed here.

MIOSHA says an engineer needs to design the protective system (slope, bench or shoring) to be used in this size of an excavation.

So this is what we did.

And this was a fantastic example of creating, not only a safe work environment, but a psychological safe work environment where everyone feels they can:

1. Speak up

2. Stop work

3. Make decisions that protect human life.

And everyone on this team did that.

Quick Field Check

☐ What's the worst thing that could happen?

☐ What evidence supports our decision?

☐ What assumption are we making?

☐ Has someone independent looked at it?

☐ Would I let my own family work here?