Waste is a line item you can forecast before the bit turns. Once you know the cuttings a section makes, disposal cost is arithmetic — but only if you bulk the dry rock up for the mud that leaves with it, which is where most estimates go wrong.
Dry rock isn't what you haul
The cuttings-volume calculation gives solid rock. What actually goes to the skip is wet — coated in mud, with fluid held on every particle and in the void space. That retained fluid can add half again to the volume, and it's what makes oil-on-cuttings a compliance and cost problem at once. Forecast the wet volume, not the dry.
From volume to money
Multiply the wet waste volume by your disposal rate — haulage plus treatment, whether that's thermal desorption, cuttings re-injection or landfarming. The rate varies enormously by route and jurisdiction, so the volume is the part worth getting right; the rate you take from your contract.
The equation
Wet waste volume and cost:
Wet waste (m³) = Dry cuttings (m³) × Bulking factor
Disposal cost = Wet waste (m³) × Rate ($/m³)
Bulking factor ≈ 1.4–1.8 for retained fluid and void space; the rate is your haul-and-treat contract price.
Two levers move this number: cut retained fluid (drier cuttings off the shaker and dryer, lower oil-on-cuttings) and choose the disposal route wisely. A cuttings dryer that drops the bulking factor from 1.8 to 1.4 takes real money off every section — and often keeps you the right side of a discharge limit.
Common questions
Why not just use the dry cuttings volume?
Because you don't dispose of dry rock — you dispose of wet, mud-coated cuttings plus void space. Costing on the dry figure understates the haul and treatment volume, sometimes by 40–80%.
What drives the disposal rate?
The route and the jurisdiction. Landfarming, re-injection, thermal desorption and offshore skip-and-ship all carry very different unit costs, and oil-on-cuttings limits can force a more expensive route — so the rate is contract- and location-specific.
