# Relationship history for MSHA mine 3901493

Current hierarchy: **Leo  Wanzek → Wanzek Construction, Inc → Tollefson Gravel 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:** Wanzek Construction, Inc → Tollefson Gravel Pit; 2004-04-30 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Leo  Wanzek → Tollefson Gravel Pit; 2004-04-30 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Leo  Wanzek → Wanzek Construction, Inc; 2004-04-30 to current/open; source msha-controller-operator-history