Plumbing crews dig. That puts trenching, one of construction's deadliest activities, at the center of your training plan.
OSHA cards
OSHA 10 Construction for all field workers and OSHA 30 for foremen is the common GC expectation. In Connecticut, a licensed plumber whose OSHA 10 is five or more years old needs a 4-hour supplemental refresher from an OSHA-authorized trainer before starting on a covered public works project.
Excavation competent person
Every excavation needs a competent person who inspects it daily before work and after rain or other hazard-increasing events (1926.651(k)). That person must be able to identify hazards and have the authority to fix them. On a plumbing crew this is often the foreman. Document their excavation training separately from OSHA 30.
Key numbers your competent person must know: protective systems at 5 feet, a ladder within 25 feet of travel in trenches 4 feet or deeper, spoil at least 2 feet back, and an engineer-designed system beyond 20 feet.
Confined spaces
Manholes, vaults and some crawlspaces may be permit-required confined spaces under 1926 Subpart AA. Entrants, attendants and supervisors each need role-specific training.
Other credentials
- Silica controls for cutting concrete or masonry.
- Hazard communication for solvents, cements and cleaners.
- CPR/First Aid.
- Medical evaluation and respirator fit test records where respirators are used, with fit tests repeated annually.
Trench safety, in detail
Trench collapses kill workers every year, and plumbing crews installing water, sewer and storm lines are among the most exposed. The excavation rules in 29 CFR 1926 Subpart P are short; every foreman should know them well.
Before anyone digs
- Locate utilities. 1926.651(b) requires the estimated location of underground utilities to be determined before opening an excavation. In practice that means calling 811 and waiting the time your state's law sets, then exposing lines carefully by hand or vacuum excavation.
- Plan the protective system. Decide in advance whether you will slope, bench, shore or use a trench box, and have the equipment on site.
- Check access and spoil. Spoil and equipment at least 2 feet from the edge; a ladder, ramp or stairway within 25 feet of lateral travel in trenches 4 feet or deeper.
Protective systems and soil types
Trenches 5 feet deep or more need a protective system unless they are entirely in stable rock. Trenches under 5 feet need one too if the competent person finds signs of possible cave-in. Appendix A of Subpart P classifies soil as stable rock, Type A, Type B or Type C. For sloping without a design, the maximum allowable slopes are:
| Soil type | Maximum slope (horizontal:vertical) | Angle |
|---|---|---|
| Type A | ¾ : 1 | 53° |
| Type B | 1 : 1 | 45° |
| Type C | 1½ : 1 | 34° |
Beyond 20 feet deep, a registered professional engineer must design the protective system. Trench boxes and shoring must be used according to the manufacturer's tabulated data, which should be on site.
Daily inspections and atmospheres
The competent person inspects the excavation, adjacent areas and protective systems daily before work starts, as needed during the shift, and after rain or anything else that increases the hazard. Where an oxygen-deficient or hazardous atmosphere could exist, such as near sewers, landfills or gas lines, test the air before workers enter trenches deeper than 4 feet (1926.651(g)).
Record these inspections. A one-page daily excavation checklist, signed by the competent person, is the single most useful document on a plumbing job.
Who should be the competent person
OSHA defines a competent person as someone who can identify existing and predictable hazards and has authority to take prompt corrective measures. Choose the foreman who runs the trench, give them a dedicated excavation competent-person course (typically 8 hours or more, with soil testing practice), and make sure the crew knows they can stop work. When that person is off site, someone else equally trained must take over.
Confined spaces: manholes, vaults and pits
Manholes, lift stations, meter vaults and some crawlspaces can be permit-required confined spaces under 1926 Subpart AA. Hazards include hydrogen sulfide and methane in sewers, low oxygen, and engulfment. The construction rule requires the employer to identify confined spaces before work, coordinate with other employers on site, test and monitor the atmosphere, and train entrants, attendants and entry supervisors for their roles. Rescue must be planned before entry; calling 911 is not a rescue plan by itself unless the service has agreed and can respond in time.
Hot work, solder and lead
Sweating copper and brazing are hot work. Keep a fire extinguisher at hand, clear or protect combustibles, and use a fire watch where needed, following 1926.352. Propane and MAPP cylinders should be stored and transported upright and secured.
Older buildings bring lead: lead solder, lead pipe and lead-based paint on surfaces you cut through. The lead in construction standard (1926.62) requires an exposure assessment, protective measures and training where lead exposure is possible. For renovation in pre-1978 homes and child-occupied facilities, EPA's Renovation, Repair and Painting rule may also require an RRP-certified firm and renovator.
Silica, ladders and power tools
- Silica: cutting or coring concrete, block or brick for drains and penetrations creates silica dust. Follow Table 1 of 1926.1153 or measure exposures, and train exposed workers.
- Ladders and scaffolds: most plumbing falls are from ladders. Train under 1926.1060 and use the right ladder for the task.
- Pipe threaders, press tools and saws: guards in place, and training on each machine before use.
Licenses and trade certifications
OSHA training is separate from trade credentials, but they belong in the same record because they renew:
- Plumbing license with continuing-education hours set by the state or city.
- Backflow prevention tester certification, often renewed every one to three years depending on the jurisdiction.
- Medical gas installer certification for hospital and clinic work, with renewal periods set by the certifying body.
- Connecticut refresher: licensed plumbers on covered public projects need the four-hour refresher once their OSHA 10 is five years old. See the Connecticut guide.
A training matrix for a plumbing crew
| Credential | Who | Renewal |
|---|---|---|
| OSHA 10 / 30 Construction | All / foremen | No federal expiry (CT refresher at 5 years for licensed plumbers on public work) |
| Excavation competent person | Foremen running trenches | Retrain as needed |
| Confined space (entrant, attendant, supervisor) | Anyone in manholes or vaults | Retrain on change |
| Respirator medical clearance and fit test | Respirator users | Fit test annually |
| Silica training | Anyone cutting masonry | Retrain on change |
| Lead awareness / RRP | Renovation crews | RRP renewal per EPA |
| First aid/CPR | At least one per crew | Usually 2 years |
| Backflow tester | Certified testers | Per jurisdiction |
Start from the training matrix template and run a weekly trench talk with the toolbox talk generator.
Common trench mistakes
These are the situations that show up again and again in OSHA trenching reports:
- "It's only a few minutes." Workers step into an unprotected trench to make one connection. A cubic yard of soil can weigh as much as a car; there is no safe short visit.
- Box not deep enough. The trench box stops two feet below the top of a sloped trench, or the crew works outside the box.
- Spoil on the edge. The excavator operator piles spoil right at the lip, adding weight and making a path for material to fall in.
- Water. Groundwater or rain softens the walls, and nobody reinspects before work restarts.
- No ladder. Workers climb out on the shoring or the box walls.
- Competent person in name only. The foreman has the title but no training or authority to stop work.
A short daily check before anyone enters, done by a trained competent person, prevents almost all of these.
Sewer work and biological hazards
Repairing sewers, drains and septic systems exposes workers to sewage, which carries bacteria and viruses. Provide gloves, eye protection and washing facilities, train workers to wash before eating or smoking, and keep a first aid kit for cuts. Talk with workers about vaccinations their doctor may recommend for sewage work. Combine this with hazard communication training for drain cleaners and solvents.
Onboarding a new plumber or apprentice
- Before day 1: confirm the OSHA 10 card or schedule the course; collect a photo.
- Day 1: company orientation, hazard communication, PPE, ladder safety, and the trench rules: never enter an unprotected trench, and anyone can call a stop.
- Week 1: silica and power tool training; confined space awareness, so they know which spaces they must not enter.
- Month 1: respirator medical evaluation and fit test if they will wear one; first aid/CPR for anyone who may work alone.
- Later: competent-person training for apprentices moving toward foreman.
Keep each step on the worker's record with the date and the trainer's name, so nothing depends on anyone's memory later on.