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Trench Excavation Verification Checklist

Essential Checklist+

Complete these critical checks before approving the work or proceeding to the next construction stage.

✓19 Inspection Points
✓4 Verification Categories
✓Dimensions and Route+
  • Trench length was measured along the actual route on site — not scaled from a drawing.
  • Trench width is the excavation width — not the pipe or footing width. Add at least 300mm each side for installation working space, or use the Auto-Calculate Width from Pipe Diameter helper to derive it from the actual pipe diameter and clearance.
  • Trench depth is measured from existing ground level to the bottom of the pipe bedding or foundation — including any granular bedding layer.
  • Changes in trench depth or width along the route (due to gradient or crossing services) were entered using the Multiple Different-Sized Trenches feature — not approximated with one averaged width/depth pair.
  • Dimensions were entered in consistent units.
  • The trench route was walked on site and crossed services marked before dimensions were finalised.
  • Truck capacity and cost rate units (m³ vs cft) match what the supplier or contractor actually quoted — mixing units silently changes the truck-load and cost estimate.
✓Services and Underground Hazards+
  • All existing underground services along the trench route were identified from utility drawings and marked on the ground.
  • Trial holes were dug by hand within 500mm of any marked service before mechanical excavation began.
  • Electrical supply to cables within the trench zone was isolated or the cable route was confirmed safe before digging.
  • Minimum clearance from existing services was maintained — 150mm from water pipes, 300mm from gas pipes, 500mm from HV cables.
✓Shoring and Safety+
  • Trenches deeper than 1.2m in loose, sandy, or water-bearing soil have shoring, trench boxes, or battered sides.
  • Side battering (slope) for unshored trenches in non-cohesive soil is at least 1:1 from the trench bottom edge.
  • Excavated spoil is placed at least 1.0m from the trench edge — nearer placement increases collapse risk.
  • Safe means of entry and exit (ladder or steps) are provided at intervals not exceeding 6m for trenches over 1.2m deep.
  • Open trenches across pedestrian or vehicle routes are covered with rated trench plates when not being worked.
✓Volume, Bedding, and Reinstatement+
  • A bulking factor of 20–30% was applied to the calculated trench volume for spoil haulage.
  • Pipe bedding volume (granular material below and around the pipe) was calculated separately and added to the order.
  • Imported granular backfill specification was confirmed — clean gravel or crusher dust, not site-won clay or organic soil.
Full QC Checklist+

Verify trench dimensions, utilities, support, bedding, disposal, and safety.

✓27 Inspection Points
✓4 Verification Categories
✓Dimensions and Route+
  • Trench length was measured along the actual route on site — not scaled from a drawing.
  • Trench width is the excavation width — not the pipe or footing width. Add at least 300mm each side for installation working space, or use the Auto-Calculate Width from Pipe Diameter helper to derive it from the actual pipe diameter and clearance.
  • Trench depth is measured from existing ground level to the bottom of the pipe bedding or foundation — including any granular bedding layer.
  • Changes in trench depth or width along the route (due to gradient or crossing services) were entered using the Multiple Different-Sized Trenches feature — not approximated with one averaged width/depth pair.
  • Dimensions were entered in consistent units.
  • The trench route was walked on site and crossed services marked before dimensions were finalised.
  • Truck capacity and cost rate units (m³ vs cft) match what the supplier or contractor actually quoted — mixing units silently changes the truck-load and cost estimate.
  • Currency selected matches the quotation currency, especially on multi-currency or export/import projects.
  • Contingency percentage (if used) reflects how well the route is actually known — unmapped services, ground conditions, and reinstatement scope are common sources of cost overrun on trench work.
✓Services and Underground Hazards+
  • All existing underground services along the trench route were identified from utility drawings and marked on the ground.
  • Trial holes were dug by hand within 500mm of any marked service before mechanical excavation began.
  • Electrical supply to cables within the trench zone was isolated or the cable route was confirmed safe before digging.
  • Gas, water, and telecom authorities were notified before trenching in public or shared access areas.
  • Minimum clearance from existing services was maintained — 150mm from water pipes, 300mm from gas pipes, 500mm from HV cables.
✓Shoring and Safety+
  • Trenches deeper than 1.2m in loose, sandy, or water-bearing soil have shoring, trench boxes, or battered sides.
  • Side battering (slope) for unshored trenches in non-cohesive soil is at least 1:1 from the trench bottom edge.
  • Excavated spoil is placed at least 1.0m from the trench edge — nearer placement increases collapse risk.
  • Safe means of entry and exit (ladder or steps) are provided at intervals not exceeding 6m for trenches over 1.2m deep.
  • Trench is inspected by a competent person at the start of each shift and after rain or vibration from nearby plant.
  • Open trenches across pedestrian or vehicle routes are covered with rated trench plates when not being worked.
✓Volume, Bedding, and Reinstatement+
  • A bulking factor of 20–30% was applied to the calculated trench volume for spoil haulage.
  • An overbreak/over-excavation allowance (typically 5–15%) was applied where ground is loose or the excavator bucket is wide relative to the trench, so truck-load and disposal figures reflect actual dig volume, not just the theoretical geometric volume.
  • Pipe bedding volume (granular material below and around the pipe) was calculated separately and added to the order.
  • Reinstatement material volume was calculated as: trench volume − pipe volume − bedding volume.
  • Imported granular backfill specification was confirmed — clean gravel or crusher dust, not site-won clay or organic soil.
  • Reinstatement compaction requirements (layers, passes, equipment) were confirmed with the engineer or road authority.
  • Surface reinstatement (tarmac, paving, concrete) was specified and costed separately from the earthwork.
Inspection Notes+
Use the latest approved drawings, specifications, and site measurements.
Complete all critical checks before proceeding to the next work stage.
Record deviations and confirm rectification where required.

Related Calculators & Guides

Trench Excavation CalculatorOpen the related calculator and verify the current project inputs.

FAQ

Use it after collecting the project inputs and again before approving or closing the relevant work stage.
No. It supports verification but does not replace approved drawings, specifications, codes, manufacturer requirements, or professional inspection.