Excavation Risk Assessment (UK) — Template & Worked Example

Excavation work kills people in the UK every year — and the HSE's view, set out in HSG185 (Health and safety in excavations), is that almost every fatality is preventable with a properly thought-through risk assessment and method statement. This guide gives you a UK excavation risk assessment template, a worked example for a 1.8 m service trench, and the specific hazards principal contractors check for before they let groundworkers break ground.

When do you need a written excavation risk assessment?

If you employ five or more people, the Management of Health and Safety at Work Regulations 1999 (Regulation 3) requires every significant risk assessment to be recorded in writing. CDM 2015 Regulation 22 then adds specific duties for excavation work: a competent person must inspect every excavation at the start of each shift, after any event likely to have affected stability, and after any accidental fall of rock, earth or other material. That inspection has to be recorded.

In practice, every UK principal contractor will require a site-specific excavation RAMS — not just a generic risk assessment — before any digging starts. The risk-assessment half of that document is what this guide covers.

The five hazards that drive excavation risk in the UK

HSG185 names five hazard groups that cause virtually every excavation incident on UK sites. A risk assessment that doesn't address all five will be sent back at first review.

1. Collapse of the sides. Wet ground, vibration from nearby plant, surcharge loads from spoil heaps or vehicles, and changes in weather all destabilise an unsupported trench. A 1 m³ slab of soil weighs about 1.5 tonnes — anyone caught under it will not self-extract.
2. Materials, plant or people falling into the excavation. Edge protection, exclusion zones, stop blocks for plant and clear access routes mitigate this.
3. Striking buried services. Electricity cables, gas mains, water mains and fibre — every one of which can kill or close the site. CAT scan + GPR survey before breaking ground; safe-dig technique (hand-dig within 500 mm of indicated services) once ground is opened.
4. Water ingress and unstable ground. Heavy rain or a struck water main can flood a trench in minutes. Sumps, pumps, and a stop-work threshold are not optional on deep excavations.
5. Atmosphere — fumes, oxygen depletion, contaminated ground. Confined-space rules can apply to excavations > 1.2 m deep or in known contaminated land. Atmospheric monitoring before entry is then mandatory.

Excavation risk assessment template — the structure to use

Use the same row format that works for any UK construction risk assessment, but with the five hazard groups above as a checklist before you start:

Hazard · Who's at risk · Existing controls · Residual risk (L × S) · Further action

Then add the four sections principal contractors specifically check on excavation work:

• Service search evidence — utility plans referenced, CAT scan date, GPR survey reference, named operative trained to HSG47 standard.
• Support method — open-cut at an engineer-specified angle, trench box, sheet piling, hydraulic shoring. Reference the structural detail or design brief.
• Inspection schedule — name of the competent person, inspection frequency (at minimum: start of every shift), where the inspection record is kept.
• Emergency rescue plan — how a buried operative will be recovered, who calls the emergency services, where the casualty extraction route is.

Worked example: 1.8 m service trench for a foul-water connection

Scope: 32 m of 1.8 m deep × 0.6 m wide trench across a hardstanding car park, to install a 225 mm foul-water connection between a new office unit and the existing manhole. Ground is made-up granular fill over London clay. Known services: an LV electricity cable runs parallel 1.5 m off-line, marked on the utility plan and confirmed by CAT scan.

The risk-assessment table for this job runs to eight site-specific rows:

1. Collapse of trench sides in made ground · Groundworkers · Trench box (Mabey TB-1800) installed by 360° excavator from the surface, no operative in unsupported excavation, support kept within 0.5 m of the dig face · 1 × 5 = 5 · No further action.
2. Strike on the parallel LV cable · Groundworkers, public · Utility plan reviewed, CAT scan and GPR survey on 11 July, cable physically located by hand-dig at chainage 8 m and 24 m, exposed cable protected by timber boarding, no mechanical excavation within 500 mm of marked cable line per HSG47 · 1 × 5 = 5 · No further action.
3. Fall from edge into open trench · Groundworkers, follow-on trades, visitors · Edge protection (Heras with mesh infill) to all open lengths, stop blocks for plant at 2 m off the dig face, exclusion zone to the public car park enforced with hoarding · 1 × 4 = 4 · No further action.
4. Water ingress in heavy rain · Groundworkers · Submersible pump kept on site, sump dug at the low end of each open length, stop-work threshold > 25 mm rainfall in 12 hours, all trench inspections after rain logged · 2 × 3 = 6 · No further action.
5. Plant interaction (360° excavator and operatives on foot) · Groundworkers · Banksman (CPCS A73) for every plant movement in the dig area, exclusion zone enforced with cones, slewing radius marked, plant operator (CPCS A58) on the same RAMS · 2 × 4 = 8 · No further action.
6. Buried contamination — historic fuel-storage area on adjacent plot · Groundworkers · Phase 1 desk study referenced, soils inspected for staining/odour at the start of each shift, atmospheric meter on hand for confined-space-style readings if depth exceeds 1.2 m in stained soil · 2 × 3 = 6 · Further action: testing kit pre-positioned; PC to be notified if any unexpected soils encountered.
7. Manual handling — bedding aggregate and 225 mm pipe sections · Groundworkers · Mechanical lift for all bedding deliveries, two-person lift for pipe sections over 25 kg, no operative lifting from below ground level · 2 × 3 = 6 · No further action.
8. Slips and falls into the trench during pipe-laying · Pipe-layer · Non-slip soles, trench-box internal access ladder positioned at one end, no working alone — minimum two operatives on every shift, supervisor at surface · 2 × 4 = 8 · No further action.

Inspection schedule for this excavation

• Start of every shift — visual inspection by site supervisor (CSCS Gold, SSSTS), recorded on the F91 inspection form.
• After any rainfall > 25 mm in 12 hours — re-inspection before any operative enters.
• After any plant movement adjacent to the dig — visual check for spoil-heap surcharge or vibration cracking.
• Inspection record retained in PC site office; copy attached to the RAMS file at handover.

Emergency rescue plan

Trench rescue is a specialist operation. The assumption built into this RAMS is that the fire and rescue service will perform any extraction below the trench-box top, not the groundworks team:

• Stop work immediately. Do not enter an unsupported part of the trench to attempt rescue.
• Call 999. Site post-code and grid reference printed in welfare cabin.
• Casualty extraction route: open access from the car park entrance — barriers stored, not bolted, for rapid removal.
• Site first-aider (FAW) to maintain communication with casualty until brigade arrival.

Common reasons excavation risk assessments get rejected

• Service search evidence not referenced (utility plan date, CAT scan operator, GPR survey reference).
• "Trench box if required" — the support method must be specified, not conditional.
• No competent-person name for the F91-style inspection.
• Generic emergency arrangements ("call 999") with no extraction route or grid reference.
• Risk assessment treats the trench as the only hazard — ignores plant interaction, edge protection and weather.

How to use this excavation risk assessment template

Copy the structure, then rewrite every cell against your actual depth, soil, services, contamination and plant. Site-specific detail gives the competent person and receiving contractor evidence to review; the example itself cannot guarantee acceptance.

If you'd rather not start from a blank template, Riskora's free RAMS generator renders this same structure automatically — pick the construction or utilities preset, confirm the excavation hazards from a pre-loaded library, edit the controls to match your dig, and export PDF. Free tier, no card needed.

Related reading

• Worked example of a construction RAMS — full eight-section walk-through
• How to write a RAMS document in the UK — structure principal contractors expect
• Excavation & groundworks topic hub — trench safety, services, shoring and CDM duties
• Why principal contractors reject RAMS — the patterns to avoid