# Relationship history for MSHA mine 1001873

Current hierarchy: **AECOM → URS Corp → Dry Valley Mine**

- 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:** FMC Corp → Dry Valley Mine; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Washington Group International Inc → Dry Valley Mine; 1986-04-01 to 2007-11-14; source msha-controller-operator-history
- **operator_operates_mine:** Fmc Corp → Dry Valley Mine; 1991-09-01 to 2000-04-16; source msha-controller-operator-history
- **controller_controls_operator:** FMC Corp → Fmc Corp; 1991-09-01 to 2000-04-16; source msha-controller-operator-history
- **operator_operates_mine:** Astaris Production Llc → Dry Valley Mine; 2000-04-17 to 2005-03-14; source msha-controller-operator-history
- **controller_controls_mine:** Paul  Howes → Dry Valley Mine; 2000-04-17 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Paul  Howes → Astaris Production Llc; 2000-04-17 to 2005-03-14; source msha-controller-operator-history
- **operator_operates_mine:** URS Corp → Dry Valley Mine; 2005-03-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Washington Group International Inc → URS Corp; 2005-03-15 to 2007-11-14; source msha-controller-operator-history
- **controller_controls_mine:** URS Corporation → Dry Valley Mine; 2007-11-15 to 2014-12-31; source msha-controller-operator-history
- **controller_controls_operator:** URS Corporation → URS Corp; 2007-11-15 to 2014-12-31; source msha-controller-operator-history
- **controller_controls_mine:** AECOM → Dry Valley Mine; 2015-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** AECOM → URS Corp; 2015-01-01 to current/open; source msha-controller-operator-history