BCM
Initialism of bank cubic meter, a measure of the original volume of excavated material as it was in the ground, prior to removal.
BCM: earthwork volume before it was dug up
A bank cubic meter is the volume of soil, rock, or other material in its natural, undisturbed state before excavation. Once dug out, that same material occupies more space because it is no longer compacted by the weight of overburden. This distinction matters enormously in earthmoving contracts, payment schedules, and resource planning.
When you excavate, material loosens and expands. Sand might swell by 10 to 15 percent; clay by 20 to 30 percent or more. A BCM of in-situ material becomes 1.1 to 1.3 loose cubic meters (LCM) once removed from the ground. Conversely, when that loose material is compacted into embankments or fill, it shrinks back down but rarely returns to its original bank density. These volume changes are called the swell factor and the shrinkage factor, and they are critical to estimating haul distances, truck capacity requirements, and the final compacted volume of any fill placement.
Contract and Payment Implications
Excavation and earthwork contracts almost always specify payment in BCM, not loose or compacted volumes. This protects the contractor from volume surprises caused by soil type variation. A contractor who quotes a price per BCM knows that a 100 BCM cut will generate roughly 110 to 130 LCM of material to haul away, but they are paid only for the 100 BCM removed from the ground. The owner bears the cost of disposal or reuse; the contractor is protected by a known unit rate applied to surveyed volumes.
Bank cubic meters are determined by comparing surveyed cross-sections of the ground before and after excavation, or by design calculation in the case of planned cuts. Surveyors record the original ground profile, then remeasure after excavation to compute the difference. This requires accuracy to within 0.1 meters in elevation for large projects to avoid disputes over payment.
The term originates from banking and accounting: like a bank vault storing value, the ground stores a fixed volume of material in its natural state. Once withdrawn, that material's value (its volume) changes depending on how it is handled. In regions outside North America, cubic meters in situ (m³ i/s) or bulk cubic meters convey the same meaning.