CSLB Law & Business ExamSafetyHard
A crew installs a shoring (support) system in a deep trench as excavation proceeds. Per Cal/OSHA excavation standards, in what general order must the support system be installed and later removed?
- AInstallation order is unregulated; only the final removal method is specified
- BInstalled from the bottom up, and removed from the top down
- CInstalled and removed simultaneously at each depth increment
- DInstalled from the top down as excavation progresses, and removed from the bottom up as backfilling progresses
Show answer & explanationAnswer & explanation
Correct answer: D. Installed from the top down as excavation progresses, and removed from the bottom up as backfilling progresses
Cal/OSHA excavation standards require support systems to be installed progressively as the excavation deepens (top-down) and removed progressively as backfilling proceeds upward (bottom-up), to continuously protect workers and minimize the time soil is left unsupported.
Why the other options are wrong
- A. Both installation and removal order are specifically regulated, not just removal.
- B. This reverses the correct installation/removal sequence.
- C. Simultaneous installation and removal at each level is not the regulatory approach and would be unsafe.
Support System Sequencing
Trench support systems must be installed top-down as excavation deepens and removed bottom-up as backfilling occurs, minimizing exposure time to unsupported soil.
- Installation follows excavation depth (top-down)
- Removal follows backfill progress (bottom-up)
- Sequence minimizes cave-in risk during both phases
Memory trick: Down to dig, up to fill — shoring goes in top-down, out bottom-up.