# Relationship history for MSHA mine 3607979

Current hierarchy: **John W  Rich → Schuylkill Energy Resources,  Inc. → St. Nicholas Cogeneration 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Schuylkill Energy Resources Inc → St. Nicholas Cogeneration Plant; 1988-01-01 to 1990-03-15; source msha-controller-operator-history
- **controller_controls_mine:** John W  Rich et al → St. Nicholas Cogeneration Plant; 1988-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** John W  Rich et al → Schuylkill Energy Resources Inc; 1988-01-01 to 1990-03-15; source msha-controller-operator-history
- **operator_operates_mine:** Combustion Systems Services Inc → St. Nicholas Cogeneration Plant; 1990-03-16 to 1994-02-01; source msha-controller-operator-history
- **controller_controls_mine:** Asea Brown Boveri Ltd (ABB) → St. Nicholas Cogeneration Plant; 1990-03-16 to 1994-02-01; source msha-controller-operator-history
- **controller_controls_operator:** Asea Brown Boveri Ltd (ABB) → Combustion Systems Services Inc; 1990-03-16 to 1994-02-01; source msha-controller-operator-history
- **operator_operates_mine:** Schuylkill Energy Resources,  Inc. → St. Nicholas Cogeneration Plant; 1994-02-02 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** John W  Rich et al → Schuylkill Energy Resources,  Inc.; 1994-02-02 to current/open; source msha-controller-operator-history