Job Hazard Analysis: Laying pipe in trench

A general example for this task. Your JHA should reflect your crew, equipment and site — review it with a competent person before work starts.

Steps, hazards and controls

1. 1. Pre-shift check: competent person inspects trench, spoil piles, and utility locate marks

   • Hidden cracks, bulging walls, or water that can lead to a cave-inHigh
     • Competent person inspects the trench before anyone enters, at the start of every shift, and after rain or any change.
     • If there is water, cracks, sloughing, or bulging, nobody enters until it is fixed.
     • Pump out standing water before work starts.
   • Contact with buried gas, power, or water linesHigh
     • Confirm 811 locate tickets are current and marks are visible before digging.
     • Hand dig or vacuum excavate within the tolerance zone of marked lines.
     • If you smell gas or hit a line, stop, shut down equipment, and move everyone away.
   • Low oxygen or toxic gas in trenches over 4 ft deep near sewers, landfills, or fuel tanksMedium
     • Test the air with a calibrated 4-gas meter before entry and keep testing while people are inside.
     • Keep gas engines, pumps, and generators out of the trench and downwind.

2. 2. Set the trench box or shoring, keep spoil back, and place the access ladder

   • Cave-in in trenches 5 ft or deeper without a protective systemHigh
     • Use a trench box, shoring, or sloping chosen by the competent person for the soil type and depth.
     • Use the box only within the manufacturer's tabulated depth rating; keep the data sheet on site.
     • Never enter the trench outside the box or shoring.
   • Spoil, rocks, or tools falling from the edge onto workersMedium
     • Keep spoil piles and materials at least 2 ft back from the trench edge.
     • Extend the trench box above the trench edge or use a retaining barrier.
   • Falls into the trench and falls while climbing in or outMedium
     • Place an extension ladder in trenches 4 ft or deeper so no one walks more than 25 ft to reach it.
     • Extend the ladder 3 ft above the edge and tie it off; keep it inside the box.
     • Put barricades or cones around the open trench and cover holes left overnight.

3. 3. Lower pipe into the trench with the excavator and rigging

   • Struck or crushed by suspended pipe or swinging bucketHigh
     • Inspect slings, chokers, and the bucket hook before use; remove damaged rigging.
     • Workers stay out of the box and clear of the load while pipe is lowered; use a tag line.
     • Use one designated signal person with agreed hand signals.
     • Never stand under a suspended load.
   • Excavator or loaded truck near the edge causing a collapse or tippingHigh
     • Keep equipment back from the edge as far as the competent person sets; use stop logs or barricades.
     • Use backup alarms and a spotter when equipment moves near workers.
   • Struck by traffic or site vehicles while working at the edgeMedium
     • Set up traffic control with cones, signs, and a flagger when working near a roadway.
     • Wear a high-visibility vest at all times.

4. 4. Place bedding stone and set grade with a laser inside the box

   • Stone dumped from the bucket landing on workersMedium
     • Workers step to the far end of the box before the operator dumps bedding.
     • Operator dumps only on the signal person's signal.
   • Back strain from shoveling and raking stoneLow
     • Have the excavator spread most of the stone; rotate shovel work.
     • Lift with your legs and keep loads close to your body.
   • Laser beam in the eyesLow
     • Never look into the pipe laser; set it so the beam is not at eye level.

5. 5. Join pipe sections and cut pipe to length

   • Hands or feet pinched between pipe ends or between pipe and boxMedium
     • Use a come-along or pipe puller instead of pushing pipe home with the bucket when possible.
     • Keep hands off the bell end and away from the joint while the pipe is pushed.
     • Wear steel-toe boots and work gloves.
   • Silica dust when cutting concrete pipe with a cut-off sawHigh
     • Cut pipe outside the trench whenever possible.
     • Use a cut-off saw with a water feed running the whole cut.
     • Wear a respirator if cutting more than the allowed time or where water control is not effective.
   • Saw kickback, noise, and flying chipsMedium
     • Check the blade guard and blade rating before use; never remove the guard.
     • Support the pipe so the cut does not pinch the blade.
     • Wear safety glasses, face shield, and earplugs while cutting.

6. 6. Backfill and compact around the pipe

   • Carbon monoxide from a gas compactor in the trenchHigh
     • Use an electric or battery compactor, or a compaction wheel on the excavator, in deep or narrow trenches.
     • If a gas compactor is used, run the 4-gas meter and leave the trench at the first alarm.
   • Vibration and noise from the jumping-jack or plate compactorMedium
     • Rotate operators about every 30 minutes.
     • Wear earplugs or earmuffs and anti-vibration gloves.
   • Feet crushed by the compactor or by backfill dumped from the bucketMedium
     • Stay clear of the area where the bucket dumps; dump only on signal.
     • Wear steel-toe boots.

7. 7. Move the trench box forward, then clean up at the end of the shift

   • Caught or crushed while the box is dragged or liftedHigh
     • Everyone gets out of the trench before the box is moved.
     • Inspect box pins, spreaders, and lift points before each move.
   • Tripping over pipe, hoses, and tools; open trench left overnightMedium
     • Stack pipe on level ground and chock it so it cannot roll.
     • Pick up hoses, cords, and tools at the end of each shift.
     • Barricade or plate any open trench before leaving the site.