When does an excavation have to be inspected under CDM 2015?
Where an excavation has supports or battering, a competent person must inspect it at the start of the shift, after any event likely to have affected its strength or stability, and after any material unintentionally falls or is dislodged. Nobody works in it until the inspector is satisfied.
What regulation 22 requires
Regulation 22 of the Construction (Design and Management) Regulations 2015 covers excavations. You must take all practicable steps to prevent danger, including supports or battering where needed, so that nothing collapses and nobody is buried or trapped. You must also take suitable steps to stop people, work equipment or material falling in, and to stop the excavation or the ground next to it being overloaded.
Work must not be carried out in an excavation with supports or battering unless a competent person has inspected it, along with any work equipment and materials that may affect its safety, and is satisfied the work can be done safely.
When to inspect
- At the start of the shift in which the work is to be carried out.
- After any event likely to have affected the strength or stability of the excavation.
- After any material unintentionally falls or is dislodged.
If the inspector tells the person who asked for the inspection about a matter they are not satisfied with, nobody works in the excavation until it has been put right.
The inspection report
Regulation 24 deals with the paperwork. Where the inspector is not satisfied that the work can be done safely, they must tell the person who asked for the inspection about the risks before the end of the shift in which the inspection is completed. They must also write a report and provide it, or a copy, within 24 hours of completing the inspection.
Strictly, the regulation only asks for a written report where the inspector is not satisfied. Many principal contractors want every inspection written up anyway, as a record that the excavation was checked. Find out what your job expects.
The report covers who the inspection was for, the location, a description of what was inspected, the date and time, the hazards found, what was done, what further action is needed, and the author's name and position. Keep the report, or a copy, at the site until the construction work is completed, then for 3 months afterwards. It must be available for an HSE inspector.
One report is enough where several start-of-shift inspections fall within a 7-day period.
The main risks
- Collapse. HSE says no ground can be relied on to stand unsupported in all circumstances, and a cubic metre of soil can weigh more than 1.5 tonnes.
- Falls. People or plant can fall in, and material can fall or be dislodged from the sides or from spoil heaps.
- Services. Damaged electricity cables and gas leaks can cause explosion, fire, burns or electrocution. Overhead power lines are a risk for tipper bodies and excavators.
- Nearby structures. Digging must not undermine scaffold footings, buried services or neighbouring foundations. Low garden and boundary walls are easily undermined.
- Water, which can flow in below the natural water level and add load to the supports.
Work that puts people at risk of burial under earthfalls is listed in Schedule 3 as work involving particular risks, so where it applies the construction phase plan needs specific measures for it.
Controls
- Decide the support you need before digging, and have trench sheets, props and baulks on site before work starts.
- Where battering is used, slope granular soils more gently than their natural angle of repose, and wet ground flatter still.
- Do not park plant and vehicles close to the sides.
- Use substantial edge protection where people could fall, and toe boards or projecting sheets to stop material falling in. Wear head protection.
- Ladders need a firm, level base, must be secured, and should extend at least 1 metre above the landing point unless there is another handhold.
- Identify and control the risks from underground services before digging starts.
- Do not run petrol or diesel engines in the excavation unless fumes are safely ducted away or ventilation is forced.
- Before digging near a wall or foundation, decide if extra support is needed and consider a survey or a structural engineer's advice.