# Relationship history for MSHA mine 1102980

Current hierarchy: **Michael P  Vondra → Bluff City Materials, Inc. → Portable Plant #2**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **controller_controls_mine:** Michael P  Vondra → Portable Plant #2; 1990-10-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Bluff City Materials, Inc. → Portable Plant #2; 1995-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Michael P  Vondra → Bluff City Materials, Inc.; 1995-08-01 to current/open; source msha-controller-operator-history