# Relationship history for MSHA mine 2002907

Current hierarchy: **Daniel  Groenke → Barber Creek Sand & Gravel Inc → B.C. PORTABLE I**

- 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:** Daniel  Groenke → B.C. PORTABLE I; 1984-12-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Barber Creek Sand & Gravel Inc → B.C. PORTABLE I; 1993-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Daniel  Groenke → Barber Creek Sand & Gravel Inc; 1993-08-01 to current/open; source msha-controller-operator-history