Waste Dump Capacity Estimator
A waste dump stores material at its loose, dumped state, so the space it occupies is a loose cubic metre (LCM) volume: LCM = footprint area x average height (or your surveyed loose volume).
Enter Values
Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter either the dump footprint area and average built height (the tool multiplies them for loose volume), or type a loose volume (LCM) you already have from a survey or design.
- Enter the swell factor (loose divided by bank, e.g. 1.30 for typical rock) and the loose dumped density in t/m3.
- Read off the loose volume (LCM), the equivalent in-situ bank volume (BCM), and the stored mass in tonnes.
How it works
A waste dump stores material at its loose, dumped state, so the space it occupies is a loose cubic metre (LCM) volume: LCM = footprint area x average height (or your surveyed loose volume). Because excavated rock bulks up when it is broken and dumped, the bank volume it originally occupied in the ground is smaller: in-situ bank volume (BCM) = LCM / swell factor. Stored tonnes are the dumped mass: tonnes = LCM x loose (dumped) density.
The swell factor converts between loose and bank states (a 1.30 swell means 1 m3 of solid rock becomes 1.30 m3 loose). Reporting both LCM and BCM lets you check remaining dump capacity in loose terms while reconciling against the bank volume mined. Loose density here is the settled, dumped density on the dump, which is lower than in-situ density because of the void created by swell.
Worked example
A dump lift 45,000 m2 x 30 m at 1.30 swell. A waste dump lift covers 45,000 m2 with an average built height of 30 m. Loose volume (LCM) = 45,000 x 30 = 1,350,000 m3. With a swell factor of 1.30, in-situ bank volume (BCM) = 1,350,000 / 1.30 = 1,038,462 m3. At a loose dumped density of 1.8 t/m3, stored mass = 1,350,000 x 1.8 = 2,430,000 t (2,430 kt). That is the tonnage of overburden the lift has absorbed.
Common mistakes
- Mixing up loose and bank volume. The dump holds loose cubic metres (LCM); dividing by the swell factor gives the smaller in-situ bank volume (BCM) that was mined. Do not compare a dump's LCM directly against a pit's BCM without converting.
- Using in-situ density instead of loose dumped density for the stored tonnes. In-situ density (which includes no swell voids) will overstate the mass a dump of a given loose volume actually holds.
- Entering the swell factor as a percentage (e.g. 30) instead of a ratio (1.30). A swell of 30% is a factor of 1.30; entering 30 divides the volume by 30 and understates BCM.
Frequently asked questions
What is the difference between LCM and BCM here?
LCM (loose cubic metres) is the swelled, dumped volume the material occupies on the waste dump. BCM (bank cubic metres) is the in-situ volume it occupied in the ground before it was excavated and bulked up. They are related by the swell factor: BCM = LCM / swell. This tool reports both so you can size the dump in loose terms and reconcile it against bank volume mined from the pit.
Which swell factor should I use?
Use the site's measured swell for the material type. Typical values run about 1.10-1.20 for sand and soils, 1.25-1.40 for weathered or blasted rock, and up to about 1.45 for hard, competent rock. Enter it as a ratio (loose divided by bank), for example 1.30, not as a percentage. Always confirm against site test data or the geotechnical design.
Is this an as-built survey or a design estimate?
It is an estimate from the numbers you enter. If you type surveyed footprint area, height and density it approximates as-built capacity; if you use design geometry it is a design estimate. Either way it assumes a uniform average height across the footprint, so it is guidance only and does not replace a proper volumetric survey, dump stability design or a competent professional's sign-off.
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Tip: Enter any known values to calculate the remaining results.
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