# Relationship history for MSHA mine 0503809

Current hierarchy: **Summit Materials LLC → Elam Sand and Gravel → Washplant 4**

- 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:** Harold  Elam → Washplant 4; 1950-01-01 to 2011-03-31; source msha-controller-operator-history
- **operator_operates_mine:** Sandco Inc → Washplant 4; 1982-09-01 to 2012-12-16; source msha-controller-operator-history
- **controller_controls_mine:** John C  Dillon et al → Washplant 4; 1982-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** John C  Dillon et al → Sandco Inc; 1982-09-01 to 2012-12-16; source msha-controller-operator-history
- **controller_controls_mine:** Summit Materials LLC → Washplant 4; 2011-04-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Sandco Inc → Washplant 4; 2012-12-17 to 2015-04-21; source msha-controller-operator-history
- **controller_controls_mine:** Summit Materials LLC → Washplant 4; 2012-12-17 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Summit Materials LLC → Sandco Inc; 2012-12-17 to 2015-04-21; source msha-controller-operator-history
- **operator_operates_mine:** Elam Sand and Gravel → Washplant 4; 2015-04-22 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Harold  Elam → Elam Sand and Gravel; 2015-04-22 to 2011-03-31; source msha-controller-operator-history
- **controller_controls_operator:** Summit Materials LLC → Elam Sand and Gravel; 2015-04-22 to current/open; source msha-controller-operator-history