# Relationship history for MSHA mine 3800624

Current hierarchy: **Bill  Barrier → B & T Sand Company Inc → B & T Sand Pit**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** B & T Sand Company Inc → B & T Sand Pit; 1987-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Bill  Barrier → B & T Sand Pit; 1987-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Bill  Barrier → B & T Sand Company Inc; 1987-07-01 to current/open; source msha-controller-operator-history