# Relationship history for MSHA mine 1001735

Current hierarchy: **Bayer AG → Ruveon LLC → Bayer Quartzite Quarry**

- 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:** AECOM Energy & Construction, Inc. → Bayer Quartzite Quarry; 1986-04-01 to 2020-01-31; source msha-controller-operator-history
- **controller_controls_mine:** Washington Group International Inc → Bayer Quartzite Quarry; 1986-04-01 to 2007-11-14; source msha-controller-operator-history
- **controller_controls_operator:** Washington Group International Inc → AECOM Energy & Construction, Inc.; 1986-04-01 to 2007-11-14; source msha-controller-operator-history
- **controller_controls_mine:** URS Corporation → Bayer Quartzite Quarry; 2007-11-15 to 2014-12-31; source msha-controller-operator-history
- **controller_controls_operator:** URS Corporation → AECOM Energy & Construction, Inc.; 2007-11-15 to 2014-12-31; source msha-controller-operator-history
- **controller_controls_mine:** AECOM → Bayer Quartzite Quarry; 2015-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** AECOM → AECOM Energy & Construction, Inc.; 2015-01-01 to 2020-01-31; source msha-controller-operator-history
- **operator_operates_mine:** Rust Constructors Inc. → Bayer Quartzite Quarry; 2020-02-01 to 2024-02-06; source msha-controller-operator-history
- **controller_controls_mine:** AECOM → Bayer Quartzite Quarry; 2020-02-01 to 2021-01-01; source msha-controller-operator-history
- **controller_controls_operator:** AECOM → Rust Constructors Inc.; 2020-02-01 to 2021-01-01; source msha-controller-operator-history
- **controller_controls_mine:** SCCI National Holdings, Inc → Bayer Quartzite Quarry; 2021-01-02 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** SCCI National Holdings, Inc → Rust Constructors Inc.; 2021-01-02 to 2024-02-06; source msha-controller-operator-history
- **controller_controls_mine:** Bayer AG → Bayer Quartzite Quarry; 2021-11-09 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Ruveon LLC → Bayer Quartzite Quarry; 2024-02-07 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Bayer AG → Ruveon LLC; 2024-02-07 to current/open; source msha-controller-operator-history