Two errors that cancel out

Anyone who checks settlement calculations knows this. The arithmetic is rarely wrong. An index carried past the preconsolidation pressure, a groundwater level read in the dry season: two errors cancel out and the number looks fine. Finding them means tracing every input, with the grading plan already out.

One case on our Try page: a junior engineer's settlement calculation for a park-and-ride fill. Yesper reran it in the firm's own workbook: 8.4 in., not 1.5 in. The clay was past its preconsolidation pressure but computed with Cr; a dry-season groundwater level pulled the other way.

The engineer of record sees the real number before the fill height is fixed. Mitigation is decided in design, not once the tie-in has settled. Same for the neighbouring jobs on the Try page: a reinforced soil wall checked before issue, shear strength pulled from CPT and probe logs.

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