Trench Excavation and Spoil Calculator

How much a trench digs out, how much goes back in, and how much leaves site in bank, loose and tonnes.

Pick the pipe and its size, set the trench width, the depth to invert and the length, and choose how the trench is held open. The section follows what you set. Everything dug either goes back in the trench or leaves site: what leaves is the ground the pipe and its imported embedment take the place of, or all of it if the native material is carted.

Pipe

What happens to the native material

Trench support

Trucks

Pipe sizeDN375OD 462 mm

Trench width at the pipemm

Depth to invertmm

Bed under pipemm

Overlay above pipemm

Trench lengthm

Bulking, bank to loosex

Loose on the truck is bank in the ground times this. Clay and loam about 1.3, sand lower, rock and wet clay higher.

Density in the groundt/m³

Tonnes do not change with bulking, so trucks are worked out by weight. Clay and loam about 1.8, sand 1.6, rock 2.2 or more.

Over 50 m of trench

	Bank m³	Loose m³	Tonnes
Dig
Back in the trench
Leaves site

Back in, 0 m³ bankLeaves site, 0 m³ bank

Trench depth, surface to floor
Width at the pipe, at the surface
Dig per metre, bank
Pipe, displaces
Imported embedment zone, displaces
Truck loads

Bank is the volume in the ground, loose is after bulking on the truck, tonnes are bank times the density in the ground. Loads are by weight and rounded up. Check the section against the trench before you book trucks.

Trench width defaults to the pipe outside diameter plus the side zone each side: council stormwater rule for concrete, the SEQ Code clearance (SEQ-SEW-1200-2) for sewer and PE. Benching follows the Queensland Excavation Work Code of Practice: no vertical face over 1.5 m without support, benched so the overall slope is no steeper than 1 to 1 in ordinary ground; confirm with the geotechnical advice for the site. A 6D Civil field tool: it gives a quantity from the dimensions you enter, not a design. Suggestions to admin@6dcivil.com.au · 0437 696 753