BreachCalc

Historical record: During a main replacement, sensing lines remained on the retired pipe. Depressurizing that pipe caused regulators to open fully, overpressurizing the active network. The NTSB identified management and oversight failures and inadequate overpressure protection. One person died, 22 people were transported to hospitals, and 131 structures were damaged.

Training alternative: The verified-change path assumes a hold point, verified sensing relocation and a review of independent protection. It illustrates a barrier to this failure mechanism; it does not quantify avoided loss or reconstruct an actual successful intervention. Animation timing is compressed. No physical pressure calculations, restoration forecasts or incident cost estimates are used.

Drawings, dependencies, cross-team review and field verification are change-review prompts, not field operating instructions. The financial calculator below remains a separate model.

• NTSB · findings and documented consequences
• NTSB · final report PAR-19/02
• Northeast Gas Association · management-of-change lessons

Research accessed October 12, 2026.