# Relationship history for MSHA mine 1401499

Current hierarchy: **Burnette  Dirks; Byron  Dirks → Northridge Sand LLC → Northridge Sand LLC**

- 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

- **controller_controls_mine:** L A  Knebler → Northridge Sand LLC; 1983-08-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** L A Knebler Construction Company Inc → Northridge Sand LLC; 1986-06-01 to 1997-03-13; source msha-controller-operator-history
- **controller_controls_operator:** L A  Knebler → L A Knebler Construction Company Inc; 1986-06-01 to 1997-03-13; source msha-controller-operator-history
- **controller_controls_mine:** Superfos America Inc → Northridge Sand LLC; 1988-12-29 to 2000-02-21; source msha-controller-operator-history
- **operator_operates_mine:** Couch Construction Materials → Northridge Sand LLC; 1997-03-14 to 2000-01-12; source msha-controller-operator-history
- **controller_controls_operator:** Superfos America Inc → Couch Construction Materials; 1997-03-14 to 2000-01-12; source msha-controller-operator-history
- **operator_operates_mine:** Northridge Sand LLC → Northridge Sand LLC; 2000-01-13 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Burnette  Dirks  et al → Northridge Sand LLC; 2000-01-13 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Burnette  Dirks  et al → Northridge Sand LLC; 2000-01-13 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Byron  Dirks et al → Northridge Sand LLC; 2000-01-13 to current/open; source msha-controller-operator-history