Waste Settlement and Recovered Airspace
Splits settlement into primary, recoverable as airspace while the cell is open, and secondary.
Example
You enter
- Waste thickness (ft) 100
- Filled area (acres) 50
- Primary settlement (% of thickness) 8
- Secondary settlement (% of thickness) 12
- In-place density (lb/cy) 1200
- Tipping fee ($/ton) 45
- Cap drainage slope (%) 4
- Slope run length (ft) 300
- Adjacent fill thickness (ft) 50
You get
- Total settlement 20.0 ft -- 8.0 primary, 12.0 secondary
- Primary settlement (ft) 8
- Secondary settlement (ft) 12
- Volume the settlement creates 1613330
- Recoverable airspace 645333
- Recoverable (ton) 387200
- What that carries 17424000
- Differential against the adjacent fill 10.0 ft (10.0 ft there against 20.0 ft here)
- Design fall (ft) 12
- Remaining slope (%) 0.666667
- Fall consumed (%) 83.3333
Details, formula, and sources
Which only lowers the final grades, then checks the differential against the cap's design fall. The worked cell recovers $17.4M of airspace and loses 83% of its cap slope to differential settlement.
settlement = waste thickness x the primary and secondary fractions; recoverable airspace = primary settlement x area; differential = the settlement difference between adjacent fill thicknesses, against the cap's design fall over its run.
Settlement as a fraction of waste thickness. The site's own settlement monitoring, the closure plan, and the permit's minimum final-cover slope govern.
Public arithmetic; the settlement fractions come from the site's own monitoring.
Estimate. AHJ and licensed professional govern.
Field names used by the API: waste_thickness_ft, filled_acres, primary_settlement_pct, secondary_settlement_pct, in_place_density_lb_per_cy, tipping_fee_per_ton, cap_slope_pct, slope_run_ft, adjacent_thickness_ft, total_settlement_ft, primary_settlement_ft, secondary_settlement_ft, total_volume_cy, recoverable_airspace_cy, recoverable_tons, recoverable_revenue, differential_settlement_ft, design_fall_ft, remaining_slope_pct, fall_consumed_pct
- Differential not the total, is the number that governs the cap; final grades are designed with the settlement added back inclosure plan
- Settlement fractions entered; they are highly waste and site specific and are not predicted heresite settlement monitoring