# Relationship history for MSHA mine 4202357

Current hierarchy: **Kirk A  Benson → Headwaters Incorporated → Environmental Technologies Group, LLC**

- 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:** Brent M  Cook → Environmental Technologies Group, LLC; 1999-02-01 to 2002-12-01; source msha-controller-operator-history
- **operator_operates_mine:** Headwaters Incorporated → Environmental Technologies Group, LLC; 2002-12-02 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Kirk A  Benson et al → Environmental Technologies Group, LLC; 2002-12-02 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Kirk A  Benson et al → Headwaters Incorporated; 2002-12-02 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Brent M  Cook → Headwaters Incorporated; 2002-12-02 to 2002-12-01; source msha-controller-operator-history