# Relationship history for MSHA mine 3800716

Current hierarchy: **Martin Marietta Materials Inc → Bluegrass Materials Company, LLC → Calhoun Sand**

- 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:** Bill  Barrier → Calhoun Sand; 1987-07-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** B & T Sand Co Inc → Calhoun Sand; 2007-06-30 to 2015-10-02; source msha-controller-operator-history
- **controller_controls_operator:** Bill  Barrier → B & T Sand Co Inc; 2007-06-30 to 2015-10-02; source msha-controller-operator-history
- **controller_controls_mine:** Panadero Aggregates Holdings, LLC → Calhoun Sand; 2010-08-26 to 2018-04-26; source msha-controller-operator-history
- **operator_operates_mine:** Bluegrass Materials Company, LLC → Calhoun Sand; 2015-10-03 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Panadero Aggregates Holdings, LLC → Bluegrass Materials Company, LLC; 2015-10-03 to 2018-04-26; source msha-controller-operator-history
- **controller_controls_mine:** Martin Marietta Materials Inc → Calhoun Sand; 2018-04-27 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Martin Marietta Materials Inc → Bluegrass Materials Company, LLC; 2018-04-27 to current/open; source msha-controller-operator-history