# Relationship history for MSHA mine 4702823

Current hierarchy: **Richard C  Schumitsch → MERRILL GRAVEL & CONSTRUCTION CO → Portable Plant No. 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **controller_controls_mine:** Richard C  Schumitsch → Portable Plant No. 1; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Merrill Gravel & Construction Company → Portable Plant No. 1; 1986-04-01 to 1988-04-12; source msha-controller-operator-history
- **controller_controls_operator:** Richard C  Schumitsch → Merrill Gravel & Construction Company; 1986-04-01 to 1988-04-12; source msha-controller-operator-history
- **operator_operates_mine:** Cain Creek Enterprises Inc → Portable Plant No. 1; 1988-04-13 to 2026-09-15; source msha-controller-operator-history
- **controller_controls_mine:** Mary J  Schumitsch → Portable Plant No. 1; 1988-04-13 to 2016-08-23; source msha-controller-operator-history
- **controller_controls_operator:** Mary J  Schumitsch → Cain Creek Enterprises Inc; 1988-04-13 to 2016-08-23; source msha-controller-operator-history
- **controller_controls_mine:** Richard C  Schumitsch → Portable Plant No. 1; 2016-08-24 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Richard C  Schumitsch → Cain Creek Enterprises Inc; 2016-08-24 to 2026-09-15; source msha-controller-operator-history
- **operator_operates_mine:** MERRILL GRAVEL & CONSTRUCTION CO → Portable Plant No. 1; 2026-09-16 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Richard C  Schumitsch → MERRILL GRAVEL & CONSTRUCTION CO; 2026-09-16 to current/open; source msha-controller-operator-history