# Relationship history for MSHA mine 0302020

Current hierarchy: **Steve R  Hackman → T&H Sand Company → T&H Sand Plant #3**

- 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:** Steve R  Hackman et al → T&H Sand Plant #3; 2010-11-08 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** T&H Sand Company → T&H Sand Plant #3; 2011-10-12 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Steve R  Hackman et al → T&H Sand Company; 2011-10-12 to current/open; source msha-controller-operator-history