# Relationship history for MSHA mine 2302278

Current hierarchy: **Steven W  Engemann → Hermann Sand & Gravel Inc → Hermann Sand-Jefferson City Plant**

- 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

- **controller_controls_mine:** Steven W  Engemann → Hermann Sand-Jefferson City Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Gregory J Muenks et al → Hermann Sand-Jefferson City Plant; 1990-02-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Muenks Brothers Quarries Inc → Hermann Sand-Jefferson City Plant; 2003-02-10 to 2008-08-05; source msha-controller-operator-history
- **controller_controls_operator:** Gregory J Muenks et al → Muenks Brothers Quarries Inc; 2003-02-10 to 2008-08-05; source msha-controller-operator-history
- **operator_operates_mine:** Hermann Sand & Gravel Inc → Hermann Sand-Jefferson City Plant; 2008-08-06 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Steven W  Engemann → Hermann Sand & Gravel Inc; 2008-08-06 to current/open; source msha-controller-operator-history