# Relationship history for MSHA mine 2002507

Current hierarchy: **Hirs Gene → Waterford Sand & Gravel Company → Waterford Pit**

- 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:** Waterford Sanitary Landfill Corp → Waterford Pit; 1979-01-01 to 1980-01-31; source msha-controller-operator-history
- **controller_controls_mine:** Malnar Edward H → Waterford Pit; 1979-01-01 to 1980-01-31; source msha-controller-operator-history
- **controller_controls_operator:** Malnar Edward H → Waterford Sanitary Landfill Corp; 1979-01-01 to 1980-01-31; source msha-controller-operator-history
- **operator_operates_mine:** Waterford Sand & Gravel Company → Waterford Pit; 1980-02-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Hirs Gene → Waterford Pit; 1980-02-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Hirs Gene → Waterford Sand & Gravel Company; 1980-02-01 to current/open; source msha-controller-operator-history