# Relationship history for MSHA mine 2104042

Current hierarchy: **Tom  Chard; Dan  Chard → Chard Grading and Excavation LLC → Sibley Pit Wash Plant/ Screener**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **controller_controls_mine:** Dan  Chard et al → Sibley Pit Wash Plant/ Screener; 2020-01-31 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Chard Grading and Excavation LLC → Sibley Pit Wash Plant/ Screener; 2023-02-16 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Dan  Chard et al → Chard Grading and Excavation LLC; 2023-02-16 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Tom  Chard et al → Chard Grading and Excavation LLC; 2023-02-16 to current/open; source msha-controller-operator-history