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Excavation, pipe bedding stone, backfill and spoil to haul for any trench.
With these inputs:
| Result | Value |
|---|---|
| Soil to excavate | 16.67 yd³ (12.74 m³) |
| Bedding stone | 8.62 tons (7.82 t) |
| Spoil pile (loose) | 20.83 yd³ (15.93 m³) |
| Leftover soil to haul or spread | 8.1 yd³ (6.19 m³) |
| Excavation per foot of trench | 0.167 yd³ |
| Pipe zone (stone) height | 14 in (35.6 cm) |
| Bedding stone volume | 6.16 yd³ (4.71 m³) |
| Volume taken by the pipe | 0.32 yd³ (0.25 m³) |
| Soil backfilled above the stone (in-place) | 10.19 yd³ (7.79 m³) |
| Stone | #57 Crushed Stone (3/4"), washed — 1.4 tons per yd³ |
| Trench safety | Under 4 ft (36 in) |
Call 811 a few days before you dig so buried utility lines are marked. Compact backfill in 6–8 inch lifts so the trench doesn't settle into a ditch.
A trench is three jobs: digging the soil out, bedding the pipe in stone, and putting soil back. This calculator measures each one — the cubic yards you excavate, how much that soil swells in the spoil pile, the stone for the pipe zone (minus the pipe itself), the soil that goes back and the surplus left over — in imperial or metric.
Length × width × depth, all in feet, divided by 27 for cubic yards. A trench 100 ft long, 18 in wide and 36 in deep is 100 × 1.5 × 3 = 450 cu ft, or 16.7 cubic yards.
Multiply the trench width and length by the stone depth (bedding under the pipe + the pipe + cover over it), then subtract the pipe's own volume. For 100 ft of 4 in pipe in an 18 in trench with 4 in under and 6 in over, that is about 6.2 cubic yards, roughly 8.6 tons of #57 stone.
Soil swells when it is dug because the packed grains loosen. Common earth takes up about 25% more room in the pile, clay more. That matters when you size a dumpster or count truckloads.
OSHA requires a protective system — sloping, shoring or a trench box — for trenches 5 feet deep or more unless they are entirely in stable rock (29 CFR 1926.652). From 4 feet, a ladder or ramp must be within 25 feet of travel.
Usually 12 to 18 inches: wide enough to place and bed the pipe and compact stone along its sides. Deeper trenches that people work in must be wider to be dug and protected safely.
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