Backfilling & Compaction
The end of a trench job is still dangerous. Workers are hurt pulling shoring, compacting in trenches that are no longer protected, and getting crushed by remote-controlled rollers. Backfilling needs the same planning as digging.
- Construction
- Laborers
- Equipment operators
Photo: laborer running a plate compactor on a backfill lift inside a trench box, with the box being pulled up in stages
Removing protective systems
- Remove shoring and shields from the bottom up, as backfill is placed, so workers are never exposed to an unprotected wall.
- Release shoring slowly, and watch the walls for movement.
- Get everyone out of a trench box before it’s lifted or pulled. See Trench Boxes.
- Don’t remove protection early to “speed up” backfill.
Compacting in lifts
- Place backfill in layers (lifts) of the thickness the spec requires, and compact each before adding the next.
- Use the bedding and backfill materials the utility or engineer specifies around pipes. See Supporting Exposed Utilities.
- Poor compaction leads to sinkholes and settling that can damage utilities and roads later.
Compaction equipment
| Equipment | Hazards |
|---|---|
| Rammer (“jumping jack”) | Foot injuries, hand-arm vibration, back strain, tipping over |
| Plate compactor | Foot and leg injuries, vibration, losing control on slopes |
| Remote-controlled trench roller | Crushing the operator or others against the trench wall or another object |
| Gas-powered compactors in trenches | Carbon monoxide builds up in the trench |
Remote-controlled trench rollers have crushed operators and coworkers. Stay out of the roller’s path, operate from outside the trench or from behind it, never stand between the roller and a wall, and use machines with operator-presence detection where available.
Checklist
- Protection stays in place until backfill reaches it
- Safety-toe boots, hearing protection and gloves for compaction
- CO monitoring or electric equipment in trenches
- Compactor guards and controls work
- Nobody in the roller’s path
- Lifts no thicker than the spec
Standards & references
- 29 CFR 1926.652(e): Removal of support systems
- See also: Rollers & Compactors · Hand-Arm Vibration · Carbon Monoxide
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