Protective System Adequacy

1926.652(a)(1) States

“Each employee in an excavation shall be protected from cave-ins by an adequate protective system designed in accordance with paragraph (b) or (c) of this section . . . “

What determines “protective system adequacy”? Here’s a short list of things that come to mind and are listed in no particular order of importance.

1. To be “adequate” the protective system must come from one of the eight options found in paragraph (b) and (c). It must be from only one of those options.

Some examples of protective systems that are NOT considered adequate include leaning steel plates against the vertical excavation walls, plywood with 4” X 4” bracing, stand-alone steel sheet piling, benching Type C soil, etc. ??

2. Use protective systems in conjunction with competent soil classification. A competent person should be able to classify the soil using appendix A of subpart P and arrive at a Type A, Type B, or Type C rating. This is covered in competent person training classes.

3. When installing shoring, the proper vertical and horizontal placement of the shores are important. This can be determined by referencing the tabulated data.

4. When using trench shields, make sure the shields are rated for the depth they will be used based on the soil classification. The depth rating for shields is found in the manufacturer’s tabulated data.

5. Respect surcharge load limitations. Don’t exceed the published limitations.

6. Don’t modify protective systems. Any modification must be approved by a registered professional engineer. A common (wrong) practice is to use steel plates alongside a trench shield, but this is dangerous. Plates can add additional pressure to the shield and can cause the shield to fail, resulting in injury or death. Note, however, that there is tabulated data for use of plates at the end of the shields. That is very different from using plates on the sides of shields. Only a Registered Professional Engineer can approve the use of plates with trench shields.

7. Inspect equipment prior to use. Any damage to the protective system can affect the strength, and therefore it’s adequacy. Damaged equipment must be removed from service.

8. Using nothing at all is a practice that some employ. This is extremely dangerous. There are many reasons for doing this, but not one can be justified. All soils will cave-in and the result can be devastating.

Employers, you must have a competent person who is knowledgeable and trained and has authority to run a safe jobsite.

In closing, I would just emphasize that underground construction is the most dangerous type of construction. Per worker-hour, injuries are more frequent and more severe that other types of construction. There are so many things that can go wrong. Among many other safety concerns, it is critically important to have an adequate protective system.

For more information on this and other excavation safety topics please go to www.trenchandexcavationsafety.com

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