RAMS for Excavation & Groundworks

Excavation is one of the highest-risk activities in UK construction. Trench collapses kill several workers every year, struck-by incidents from underground services cause fatal electrocutions and gas explosions, and inadequate edge protection sends plant and people into open voids. A RAMS does not replace the CDM construction phase plan, but it is the document that translates site-specific hazards into the specific controls your operatives will follow before the first bucket goes in.

Legal Basis

The duty to produce a risk assessment sits in the Management of Health and Safety at Work Regulations 1999, regulation 3. Every employer must carry out a suitable and sufficient assessment of risks to employees and others affected by the work. For excavation, "suitable and sufficient" means identifying the actual ground conditions, buried services, proximity of structures, and the competence requirements for the work — not copying a generic document from last month's job.

Key Hazards and Controls

**Ground collapse** is the primary excavation hazard. Unsupported ground must not be entered. Before any worker descends, the excavation must be benched, battered to a safe angle, or supported with proprietary trench sheets, hydraulic props, or a drag box. The chosen method must match the ground type — granular soils behave differently from clay and require proportionally more support. Spoil and materials must be kept back at least 0.5 m from the edge to reduce surcharge loading; this also forms part of the edge protection together with substantial barriers and, where necessary, stop blocks for plant.

**Buried services** demand a structured safe-digging practice. Before breaking ground, a CAT scan (using a combined signal generator) must be completed using plans obtained from all relevant utilities. These plans are indicative, not precise — treat every service as present until confirmed absent. Within the service avoidance zone, use hand tools only; mechanical excavation stops at that boundary. Any exposed conductor must be treated as live until formally isolated. Operatives must never attempt DNO or high-voltage isolation — the correct control is to request isolation from the network operator and obtain written confirmation before resuming work. PPE alone is not a substitute for isolation.

**Atmosphere and confined spaces.** A trench is not automatically a confined space. The headline risk in an excavation is physical collapse, not atmosphere. However, if a trench is deep, enclosed, or adjacent to a known gas main or contaminated land, atmospheric monitoring for oxygen deficiency, carbon dioxide, and flammable gases must be carried out before entry and continuously during occupation. If monitoring confirms a confined space exists, a written safe system of work under the Confined Spaces Regulations 1997 must be in place before entry, including a regulation 5 rescue plan as a precondition — not an afterthought. Toxic gases are assessed against their Workplace Exposure Limits (expressed in ppm); the lower explosive limit is relevant only to the explosion risk from flammable gases.

**Asbestos.** Any disturbance of ground associated with a pre-2000 building or structure requires a refurbishment and demolition survey under the Control of Asbestos Regulations 2012 before work begins.

**Access and egress** must be provided at intervals not exceeding 6 m in any trench where workers are present, using secured ladders or purpose-made access equipment.

Common Failings That Get This RAMS Rejected

The most frequently rejected excavation risk assessments share the same weaknesses: controls copied from a template without reference to actual ground investigation data; buried services listed as a hazard with "use CAT scanner" as the sole control, with no mention of safe-digging zones or DNO notification; support methods stated as "as required" rather than specifying the system; no competence requirement named for the plant operator; and confined space risks dismissed without any atmospheric monitoring rationale.

What the Document Must Include

An excavation RAMS must state: the ground investigation information relied upon; the specific support method selected and why it is appropriate for site conditions; the buried services search and safe-digging methodology; the isolation request procedure for live conductors; the atmospheric monitoring regime and trigger levels; the access and egress arrangements; spoil management and edge protection details; plant exclusion zones; the competence and supervision requirements; and emergency arrangements including rescue provision where confined space conditions could arise.