# Relationship history for MSHA mine 2400497

Current hierarchy: **CRH PLC → MONTANA MTLS & CONS → HELENA SAND & GRAVEL-PORTABLE WASH PLANT**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **operator_operates_mine:** Maronick Construction Llc → HELENA SAND & GRAVEL-PORTABLE WASH PLANT; 1950-01-01 to 2001-12-31; source msha-controller-operator-history
- **controller_controls_mine:** Richard J  Maronick  et al → HELENA SAND & GRAVEL-PORTABLE WASH PLANT; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Richard J  Maronick  et al → Maronick Construction Llc; 1950-01-01 to 2001-12-31; source msha-controller-operator-history
- **controller_controls_operator:** Edward M  Maronick  et al → Maronick Construction Llc; 1950-01-01 to 2001-12-31; source msha-controller-operator-history
- **operator_operates_mine:** Montana Mtls & Cons → HELENA SAND & GRAVEL-PORTABLE WASH PLANT; 2002-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** CRH PLC → HELENA SAND & GRAVEL-PORTABLE WASH PLANT; 2002-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** CRH PLC → Montana Mtls & Cons; 2002-01-01 to current/open; source msha-controller-operator-history