When a laboratory reports a non-detect, it means the analyte was not measured above the detectionLimit. However, if the detectionLimit is higher than the applicable thresholdConcentration, the measurement cannot confirm the sample is below the regulatory standard — the lab simply cannot detect at a low enough concentration. Piper creates an Exceedance with isNonDetect set to true in these cases, signaling a method sensitivity issue rather than a confirmed concentration violation. Many regulatory programs require reporting these detection limit exceedances separately because they indicate inadequate analytical sensitivity for the monitoring program, not necessarily actual contamination.
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Exceedance Is Non-Detect
The `isNonDetect` flag on an Exceedance indicates that the underlying AnalyticalResult was a non-detect whose detectionLimit was itself above the regulatory thresholdConcentration.