# Relationship history for MSHA mine 2602124

Current hierarchy: **David E  Drips; John  O'Brien → Intermountain Mine Services Inc → Exchequer Canyon Project**

- 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:** Intermountain Mine Services Inc → Exchequer Canyon Project; 1989-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** David E  Drips et al → Exchequer Canyon Project; 1989-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** David E  Drips et al → Intermountain Mine Services Inc; 1989-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** John  O'Brien et al → Intermountain Mine Services Inc; 1989-08-01 to current/open; source msha-controller-operator-history