# Relationship history for MSHA mine 3201081

Current hierarchy: **Dick  Sandberg; Duane  Sandberg → Sandberg Redi-Mix, Inc. → Wash Plant**

- 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:** Duane  Sandberg et al → Wash Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Sandberg Redi-Mix, Inc. → Wash Plant; 2021-06-22 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Duane  Sandberg et al → Sandberg Redi-Mix, Inc.; 2021-06-22 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Dick  Sandberg et al → Sandberg Redi-Mix, Inc.; 2021-06-22 to current/open; source msha-controller-operator-history