Trench excavation
Estimate volume, soil expansion and hauling loads.
Measurements
US customary⚡ Quick Takeoff: Excavation Bank to Loose Swell
Undisturbed soil expands by 15% to 40% once excavated. 10 bank cubic yards (in-ground) expands into 11.5 to 14.0 loose cubic yards in your haul truck or roll-off dumpster.
HOW THE CALCULATION WORKS
Excavation estimating distinguishes between two fundamentally different volumes: Bank Measure (In-Place), which is the geometric void left in the ground, and Loose Measure (Spoil), which represents the expanded dirt requiring haul-off trucking or roll-off dumpsters.
Worked-Out Jobsite Numerical Example
Assume you are excavating a water utility line trench measuring 100 ft long, 24 inches wide, and 4 ft deep through dense common earth/clay loam (with an established 25% swell factor).
- Convert Width to Feet: 24 inches ÷ 12 = 2.0 feet.
- Calculate Bank Cubic Feet: 100 ft (L) × 2.0 ft (W) × 4.0 ft (D) = 800.0 Bank Cu Ft.
- Convert Bank Volume to Cubic Yards: 800.0 ÷ 27 = 29.63 Bank Cu Yds.
- Calculate Spoil Expansion (+25% swell): 29.63 × 1.25 = 37.04 Loose Cubic Yards.
- Calculate Spoil Weight (at ~1.15 Tons/loose yd³): 37.04 × 1.15 = ~42.6 US Short Tons.
- Determine Hauling Container Requirements (Dual-Constraint Rule):
- Volume Requirement (20-yd container): 37.04 ÷ 20 = 1.85 → 2 containers.
- Weight Requirement (at assumed 10-Ton payload limit): 42.6 Tons ÷ 10 Tons = 4.26 → 5 containers.
- Governing Haul Requirement: MAX(2, 5) = 5 roll-off containers (filled ~halfway to comply with legal road weight), OR 4 tandem dump truck loads (at ~14-ton highway payload).
📐 Calculation Methodology & Engineering Assumptions
Last Reviewed: October 2026Formulas: Bank Volume = Length (ft) × Width (ft) × Depth (ft). Convert to Yards: Cubic Feet ÷ 27. Loose Volume = Bank Volume × (1 + Swell Factor). Truckloads = Loose Volume ÷ Selected Truck Capacity.
Key Assumptions: Default swell factors represent standard uncompacted air entrainment (Sand: +15%, Common Earth: +25%, Dense Clay: +35%). Truck capacities assume legal road weight constraints (10-yd and 20-yd roll-off containers or 12-yd tandem axle dump trucks).
Verified References & Sources: OSHA 29 CFR 1926 Subpart P (Excavations & Trench Safety Standards); Caterpillar Performance Handbook Edition 49 (Earthmoving Swell & Load Factors); USDA NRCS Soil Mechanics Guidelines.
Technical Reference: Soil Swell & Weight Factors
Soil swell is governed by grain size distribution, cohesion, and moisture saturation. Cohesionless sand expands least, while cohesive heavy clay creates large angular void pockets that drastically increase haul-off requirements.
| Soil / Geotechnical Material | Bank Density (lbs/yd³) | Loose Density (lbs/yd³) | Standard Swell % | Expansion Multiplier |
|---|---|---|---|---|
| Clean Dry Sand / Loose Gravel | 2,700 lbs | 2,350 lbs | 12% – 15% | 1.12 – 1.15 |
| Common Earth / Loam / Topsoil | 2,600 lbs | 2,080 lbs | 20% – 25% | 1.20 – 1.25 |
| Dense Silt / Hardpacked Sandy Clay | 2,900 lbs | 2,230 lbs | 25% – 30% | 1.25 – 1.30 |
| Heavy Wet Clay / Gumbo | 3,100 lbs | 2,300 lbs | 30% – 38% | 1.30 – 1.38 |
| Blasted Solid Rock / Shale | 4,400 lbs | 2,900 lbs | 45% – 60% | 1.45 – 1.60 |
For complete OSHA Subpart P protective shoring tables, benching diagrams, and commercial road hauling weight schedules, review our in-depth Dirt Excavation, Trenching & Soil Swell Takeoff Guide →
Frequently Asked Questions About Trench Excavation
Results are estimates based on the dimensions and material assumptions entered. Actual material requirements can vary due to site conditions, material density, compaction, waste, supplier specifications, and construction methods. Confirm quantities with your supplier or project professional before ordering.