Start with 1,200 m³ of excavation measured in situ. If 30% is suitable for reuse, 360 m³ remains on site and 840 m³ is exported on a bank-volume basis. With an assumed 25% swell, the transport quantity becomes 1,050 m³ loose.
Those figures describe different stages of the same material. Adding them together would create a quantity that has no useful physical meaning.
CESMM4 provides a recognised civil-engineering work classification, including earthworks. Within that structure, the estimate still needs to explain the volume basis used by each calculation and quotation.
Assumed 30% reuse and 25% swell on exported bank volume. Loose volume is not additional excavation.
Follow the material through the operation
Excavation, stockpiling, rehandling and disposal may each have a different rate basis. A transport supplier might price by load, while a disposal facility may charge by mass. The conversions need stated assumptions, and those assumptions should be supported by project information where available.
In the example, an 18 m³ loose-capacity truck requires 59 theoretical loads after rounding up. That does not establish the fleet size or the achievable daily output. Cycle time, access and operating constraints need separate consideration.
A material balance helps the reviewer see where quantities leave the model. It also exposes unsupported reuse assumptions early. If the material cannot meet the required specification, both the disposal quantity and the import requirement may change.
The work-section heading is useful organisation. The balance is what makes the estimate explainable.