# Clayton Aggregates

- **MSHA mine ID:** 0400159
- **Status:** Active
- **Type / commodity:** Surface / Crushed, Broken Stone NEC
- **Location:** Contra Costa, CA
- **Operator:** Martin Marietta Northern California Aggregates,LLC
- **Controller:** Martin Marietta Materials Inc
- **Public source rows linked:** 2,113
- **Source coverage:** 15 / 20
- **Generated:** 2026-10-13T11:26:59.401Z

## Current entity hierarchy

**Martin Marietta Materials Inc (M00174) → Martin Marietta Northern California Aggregates,LLC (0064607) → Clayton Aggregates (0400159)**

Current identity source: `msha-mines`. This is a current snapshot, not a historical claim.

## Controller and operator valid-time history

- **Koppers Company Inc → Kaiser Sand & Gravel Company:** 1978-01-01 through 1988-11-13; derived from co-tenure at mine 0400159; source `msha-controller-operator-history`.
- **Hanson PLC → Hanson Aggregates, Inc.:** 1988-11-14 through 2001-12-17; derived from co-tenure at mine 0400159; source `msha-controller-operator-history`.
- **Hanson PLC → Hanson Aggregates West Inc:** 2001-12-18 through 2005-12-08; derived from co-tenure at mine 0400159; source `msha-controller-operator-history`.
- **Hanson PLC → Martin Marietta Northern California Aggregates,LLC:** 2005-12-09 through 2007-08-22; derived from co-tenure at mine 0400159; source `msha-controller-operator-history`.
- **Heidelberg Materials AG → Hanson Aggregates, Inc.:** 2007-08-23 through 2001-12-17; derived from co-tenure at mine 0400159; source `msha-controller-operator-history`.
- **Heidelberg Materials AG → Martin Marietta Northern California Aggregates,LLC:** 2007-08-23 through 2021-09-30; derived from co-tenure at mine 0400159; source `msha-controller-operator-history`.
- **Martin Marietta Materials Inc → Hanson Aggregates, Inc.:** 2021-10-01 through 2001-12-17; derived from co-tenure at mine 0400159; source `msha-controller-operator-history`.
- **Martin Marietta Materials Inc → Martin Marietta Northern California Aggregates,LLC:** 2021-10-01 through current/open; derived from co-tenure at mine 0400159; source `msha-controller-operator-history`.

- History rows: 8
- Typed edges: 18
- Interval anomalies: 2
- Valid-time bounds: inclusive; date granularity; null end means open-ended in the upstream history row; not independent proof of present control.
- Transaction-time observation: 2026-10-13T11:19:05.459773+00:00.

## Assessment signals

1. **SAFETY — 1 since 2021:** Accidents and injuries 20 historical accident/injury rows; 0 coded fatalities and 808 lost days across the published record.
2. **COMPLIANCE — 24 since 2021:** Violations and penalties 202 violation rows across the full record; 36 carry an S&S flag and $42,083 appears in current assessed amounts.
3. **HEALTH — 21 samples:** Occupational health samples 21 personal. 0 personal-sample rows have a published C/E ratio above 1; 0 noise rows have an action-level or PEL dose above 100%. These are separate measures, not a silica exceedance count. Silica results and sample status are shown separately.
4. **PRODUCTION — 0 tons:** Quarterly production and employment 9K employee hours and 18 summed average employees across reported subunits in the latest published quarter.
5. **LEGAL — 58 linked rows:** Contests, conferences and decisions 19 contested-violation rows, 19 civil-penalty docket/decision rows, and 20 conference records linked by issuance number.
6. **CONTRACTORS — 11 linked entities:** Contractors Contractors are linked through this mine’s violation or accident records. Their production and hours cover all their operations, so they are not included in this mine’s totals.
7. **INSPECTIONS — 14 since 2021:** Inspections 71 inspection events and 2K published inspection hours across the historical record.

## EIA annual operating context

No matched record in the 2024 EIA coal-public workbook. This may be inapplicable for a non-coal operation.

## Recent Title 30 crosswalk

Snapshot current through 2026-08-19.

- **30 CFR 56.20003 — Housekeeping.** (1 retained recent row) — https://www.ecfr.gov/current/title-30/chapter-I/subchapter-K/part-56/subpart-S/section-56.20003
- **30 CFR 56.14107 — Moving machine parts.** (1 retained recent row) — https://www.ecfr.gov/current/title-30/chapter-I/subchapter-K/part-56/subpart-M/section-56.14107
- **30 CFR 56.14100 — Safety defects; examination, correction and records.** (1 retained recent row) — https://www.ecfr.gov/current/title-30/chapter-I/subchapter-K/part-56/subpart-M/section-56.14100
- **30 CFR 62.170 — Audiometric testing.** (1 retained recent row) — https://www.ecfr.gov/current/title-30/chapter-I/subchapter-M/part-62/section-62.170
- **30 CFR 56.12004 — Electrical conductors.** (2 retained recent rows) — https://www.ecfr.gov/current/title-30/chapter-I/subchapter-K/part-56/subpart-K/section-56.12004
- **30 CFR 56.13015 — Inspection of compressed-air receivers and other unfired pressure vessels.** (2 retained recent rows) — https://www.ecfr.gov/current/title-30/chapter-I/subchapter-K/part-56/subpart-L/section-56.13015
- **30 CFR 41.12 — Changes; notification by operator.** (1 retained recent row) — https://www.ecfr.gov/current/title-30/chapter-I/subchapter-G/part-41/subpart-B/section-41.12
- **30 CFR 56.11027 — Scaffolds and working platforms.** (1 retained recent row) — https://www.ecfr.gov/current/title-30/chapter-I/subchapter-K/part-56/subpart-J/section-56.11027
- **30 CFR 56.14112 — Construction and maintenance of guards.** (1 retained recent row) — https://www.ecfr.gov/current/title-30/chapter-I/subchapter-K/part-56/subpart-M/section-56.14112
- **30 CFR 56.14201 — Conveyor start-up warnings.** (1 retained recent row) — https://www.ecfr.gov/current/title-30/chapter-I/subchapter-K/part-56/subpart-M/section-56.14201

## Source coverage

- **Accident, Injuries, and Illnesses:** 20 rows; 2000-03-27 through 2021-12-15; source ID `msha-accidents`
- **Addresses of Record:** 1 rows; 1973-07-25 through 1973-07-25; source ID `msha-addresses`
- **Assessed Violations:** 198 rows; 2000-06-23 through 2025-10-08; source ID `msha-assessed-violations`
- **Civil Penalty Dockets and Decisions:** 19 rows; 2009-06-16 through 2015-02-26; source ID `msha-civil-penalty-dockets-decisions`
- **Conferences:** 20 rows; 2006-02-17 through 2015-02-02; source ID `msha-conferences`
- **Contested Violations:** 19 rows; 2008-05-19 through 2014-06-26; source ID `msha-contested-violations`
- **Contractor Employment and Production — Quarterly:** 999 rows; unknown through unknown; source ID `msha-contractor-production-quarterly`
- **Contractor Employment and Production — Yearly:** 223 rows; unknown through unknown; source ID `msha-contractor-production-yearly`
- **Controller and Operator History:** 8 rows; 1978-01-01 through 2005-12-09; source ID `msha-controller-operator-history`
- **Inspections:** 71 rows; 2000-06-22 through 2026-08-21; source ID `msha-inspections`
- **Mine Employment and Production — Quarterly:** 257 rows; unknown through unknown; source ID `msha-mine-production-quarterly`
- **Mine Employment and Production — Yearly:** 54 rows; unknown through unknown; source ID `msha-mine-production-yearly`
- **Mines:** 1 rows; unknown through unknown; source ID `msha-mines`
- **Metal and Nonmetal Personal Health Samples:** 21 rows; 2004-06-24 through 2026-08-26; source ID `msha-personal-health-samples`
- **Violations:** 202 rows; 2000-06-23 through 2026-08-25; source ID `msha-violations`

## Caveats

- This is public-record decision support, not legal advice or an official MSHA record.
- Missing data can indicate no event, publication delay, an unresolved identity, or inapplicability.
- Contractor production data is entity-level and is not attributed to this mine.

## Alternate representations

- HTML: `/mines/clayton-aggregates-0400159`
- JSON: `/api/v1/mines/clayton-aggregates-0400159`
- Silica records, units, sample status and quarterly means: `/api/v1/mines/0400159/silica` (snapshot year by default; `?year=all` for history; `&format=csv` for all matching rows)
- Relationship JSON: `/api/v1/mines/0400159/relationships`
- MCP resource: `mine://0400159/assessment`
- Complete Title 30 corpus: `/data/title30-sections.json`