# Relationship history for MSHA mine 1512731

Current hierarchy: **Overbay Mary Jane → Waco Construction Company Inc → Prep 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** Aqua Processing Inc → Prep Plant; 1981-02-01 to 1981-09-02; source msha-controller-operator-history
- **controller_controls_mine:** Maupin Harry → Prep Plant; 1981-02-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Maupin Harry → Aqua Processing Inc; 1981-02-01 to 1981-09-02; source msha-controller-operator-history
- **operator_operates_mine:** Waco Construction Company Inc → Prep Plant; 1981-09-03 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Overbay Mary Jane → Prep Plant; 1981-09-03 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Overbay Mary Jane → Waco Construction Company Inc; 1981-09-03 to current/open; source msha-controller-operator-history