# Relationship history for MSHA mine 2302154

Current hierarchy: **Kevin Layne  Helton → Helton Excavating & Development Co. LLC → PLANT #1**

- 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:** Baker'S Sand & Gravel → PLANT #1; 1997-05-01 to 1998-04-15; source msha-controller-operator-history
- **controller_controls_mine:** Rick L  Baker → PLANT #1; 1997-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Rick L  Baker → Baker'S Sand & Gravel; 1997-05-01 to 1998-04-15; source msha-controller-operator-history
- **operator_operates_mine:** Helton Sand & Gravel Inc → PLANT #1; 1998-04-16 to 2014-03-05; source msha-controller-operator-history
- **controller_controls_mine:** Layton  Helton → PLANT #1; 1998-04-16 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Layton  Helton → Helton Sand & Gravel Inc; 1998-04-16 to 2014-03-05; source msha-controller-operator-history
- **operator_operates_mine:** Helton Excavating & Development Co. LLC → PLANT #1; 2014-03-06 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Kevin Layne  Helton → PLANT #1; 2014-03-06 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Kevin Layne  Helton → Helton Excavating & Development Co. LLC; 2014-03-06 to current/open; source msha-controller-operator-history