# Relationship history for MSHA mine 0404901

Current hierarchy: **Dean  Forman → EARTH TEK ENGINEERING CORP. → NORTH FONTANA**

- 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:** A & I Rock Products Inc → NORTH FONTANA; 1987-09-01 to 2002-05-06; source msha-controller-operator-history
- **controller_controls_mine:** Intravaia Ignazio → NORTH FONTANA; 1987-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Intravaia Ignazio → A & I Rock Products Inc; 1987-09-01 to 2002-05-06; source msha-controller-operator-history
- **operator_operates_mine:** Intravaia Rock & Sand Inc → NORTH FONTANA; 2002-05-07 to 2024-02-29; source msha-controller-operator-history
- **controller_controls_mine:** Ron  Willemsen → NORTH FONTANA; 2002-05-07 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ron  Willemsen → Intravaia Rock & Sand Inc; 2002-05-07 to 2024-02-29; source msha-controller-operator-history
- **operator_operates_mine:** Earth Tek Engineering Corp. → NORTH FONTANA; 2024-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Dean  Forman → NORTH FONTANA; 2024-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Dean  Forman → Earth Tek Engineering Corp.; 2024-03-01 to current/open; source msha-controller-operator-history