Digging safely with proper support and spoil control.
Excavate safely and to the right geometry for crash rated bollard foundations (332). Match sequence and shoring to soil stability (423) and maintain safe access/egress. Manage spoil and protect adjacent assets and utilities (335). Build daily inspection routines and clear stop-work triggers when obstructions or undocumented services appear (241–243). Log evidence for ITP checks and redlines (714, 937). Include one-sentence context that naturally links upward to the parent hubs (this section and the chapter hub). Add SIRA context with a link to SIRA Bollards (UAE) when relevant. Link installation pages only if helpful: What to Expect and Installation Guide.
Important: This is a general guide. For live projects we develop a tailored
Method Statement & Risk Assessment (MS/RA) and align with authority approvals (e.g., SIRA) where in scope.
613.1 Excavation sequence
Cut to design depth with benches and safe access. Sequencing readies HVM bollard sockets (332).
Plan the dig in stages: mark the array centreline and keepered openings from Setting-Out, proof utilities per Utility Search Methods, then excavate to the required Depth class. Use a leveled jig to hold socket coordinates while you trim to formation. Where multiple pits are needed, sequence so adjacent ground remains stable and access routes are maintained.
Coordinate early with concrete teams for grout beds & levelling and with drainage teams if a drainage sump is specified. Keep the dig geometry compatible with the selected foundation type and allow working room for cages, formwork, and inspection.
| Aspect | What matters | Where to verify |
|---|---|---|
| Performance | Tested system (bollard + footing) | Crash ratings — how to read |
| Operations | Duty cycles, fail-state, safety devices & measures | Installation Guide |
613.2 Soil types & stability
Match support to soil class (423). Stability protects crash rated bollard foundations.
Identify soil strata during excavation and compare to the design assumptions: granular vs cohesive, presence of fill, and groundwater. Where conditions differ, stop and consult the engineer—foundation checks (333) may change. Watch for sloughing faces and apply safety factors in bench widths and temporary works. If perched water appears, coordinate with Dewatering & Groundwater (614).
Record actual bearing level and soil description in the site diary, with georeferenced photo logs for later inclusion in the handover pack (736).
613.3 Shoring/boxing options
Use shields/frames sized to pit. Shoring keeps HVM bollard crews safe.
Choose the right shoring for pit size and depth: trench boxes (shield systems), modular frames, or sheeted pits with wailers/struts. Ensure capacity against surcharge loads (keep plant and spoil clear of edges) and confirm access for cage placement and concrete pouring. Where shallow rails or Shallow-Rail foundations are used, check that the support system doesn’t foul the rail/module or compromise alignment.
Document shoring inspections as part of the ITP, with witness/inspection forms at hold points.
613.4 Safe access/egress
Provide ladders and edge protection. Access reduces crash rated bollard incidents (351).
Install secured ladders extending above the landing, edge protection around pits, and delineated exclusion zones. Keep egress paths clear of hoses, cages, and forms. Where plant operates near pedestrians, implement a PTW & toolbox talk regime and refresh LOTO and service isolation reminders daily.
Provide lighting for early/late shifts and arrange emergency retrieval equipment if required by the risk assessment (722).
613.5 Spoil management
Stockpile clear of trenches; control silt (245). Management preserves HVM bollard areas.
Place spoil heaps at a safe setback to avoid surcharge on trench walls and prevent collapse. Keep haul routes stable and free of standing water; install silt fences or baskets where runoff could enter drains. If foundations include drainage interfaces or sumps, prevent fines from entering pipework. Plan for disposal/reuse in line with the environmental controls (726) and retain weighbridge tickets where applicable.
613.6 Adjacent structure protection
Monitor slabs and services (335). Protection prevents crash rated bollard clashes.
Where excavations are near façades, kerbs, or utilities, establish a no-go envelope and use survey targets on slabs/thresholds to check for movement. For PT slabs, use non-intrusive fixing methods and consult the structural engineer if anchors or sawcuts are required. Keep cable/duct crossings protected with boards or bridging.
613.7 Daily inspections
Record wall movement and water ingress. Inspections sustain HVM bollard safety.
Adopt a simple daily checklist: shoring integrity, wall condition, water level, ladder condition, edge protection, spoil setback, plant routes, and signage. Log with timestamped photos (937), tag any NCRs, and track closure. Share highlights at the daily huddle board to keep the crew aligned.
613.8 Unexpected obstructions
Stop-work, prove service (241–243). Protocol avoids crash rated bollard damage.
If you find hard obstructions, voids, or uncharted utilities, enact a stop-work trigger and switch to hand-dig within the hand-dig zone. Prove services using trial pits and reconcile against your GPR/EM survey and utilities schedule. Update redlines and, if needed, propose a design change (718) such as a shallower foundation option or local diversion (247).
613.9 Stop-work triggers
Define thresholds for instability or utilities hits. Triggers protect HVM bollard teams.
Typical trigger points: any wall sloughing beyond agreed tolerance; water ingress that compromises bearing; discovery of red-zone utilities; loss of ladder/edge protection; deviation from coordinates or level that risks rating-critical dependencies. Document in the MS/RA and the ITP with clear escalation—pause works, make safe, notify the accountable owner, and agree recovery actions.
Related
External resources
- NPSA — Hostile Vehicle Mitigation (HVM)
- FEMA 426 / DHS — Reference Manual to Mitigate Attacks
- ASIS — Security Risk Assessment Standard
613 Excavation & Shoring — FAQ
What shoring should I use for small, deep bollard pits?
Use modular trench boxes or framed systems sized to the pit footprint and depth. Check surcharge from plant/spoil, provide ladder access, and verify clearances for cages and pours within your ITP hold points.
How far should spoil heaps be from the trench edge?
Keep spoil and plant outside the setback defined in your MS/RA. The aim is to avoid surcharge on trench walls—setbacks typically equal or exceed trench depth unless an engineer specifies otherwise.
What if I hit an undocumented utility during excavation?
Activate the stop-work trigger, make the area safe, switch to hand-dig, and prove the service via a trial pit. Update redlines and coordinate a design response (e.g., shallow foundation, diversion) before restarting.
When do I need dewatering for bollard foundations?
When groundwater or perched water compromises bearing or safety. Coordinate with your dewatering plan (614) to maintain dry, stable formation and prevent fines from entering drains or sumps.