Ground in its natural state is packed tight. Dig it up and it loosens, taking up more space. This is swell, and it's why excavation jobs so often need more truck loads than planned.
Bank, loose and compacted volume
- Bank volume: the volume of the hole, as measured.
- Loose volume: what the dug material occupies on a truck or in a pile, which is bank × swell factor.
- Compacted volume: what it occupies after rolling or tamping back into place, often less than bank.
Typical swell factors
| Material | Swell |
|---|---|
| Sand and gravel | +10–15% |
| Common earth / loam | +20–30% |
| Clay | +30–40% |
| Rock, broken concrete | +50–80% |
Pricing removal
Dump trucks are rated by volume (10–14 cu yd for tandems) but also have weight limits. A load of wet clay can hit the weight limit before the bed is full.
Backfill
When filling, work the other way. To end up with a compacted volume, you need more loose material, typically 15–25% more for granular fill. Order accordingly.
Before you dig
Call 811 at least a few working days ahead. It's free and it's the law in most states.
This guide is general information for estimating. It is not engineering, legal or tax advice. Check local codes and your inspector for your project.