MINE DETAILS
Clayton Aggregates
MSHA MINE ID0400159
LOCATION
Mine location
1 of 1 mine with usable MSHA coordinates. Select a marker to open a mine.
Mine coordinates
- Clayton Aggregates37.93667, -121.95722Open map ↗
Quarterly trends
2025 Q1 – 2026 Q4
Database snapshot · 2026-10-13. MSHA quarterly production and employment reports.
Coal production
0reported short tons
Hours worked
53,434reported employee hours
Tons per hour
0.00production ÷ hours worked
Missing values appear as —. Totals use available reports. Tons per hour requires production and hours for the same quarters and a nonzero hours total. * Striped bars mark partial mine coverage or an incomplete quarter. See the table for coverage.
Quarterly data and reporting coverage
| Quarter | Coal (short tons) | Hours worked | Tons / hour | Avg. employees | Coverage |
|---|---|---|---|---|---|
| 2025 Q1 | 0 | 9,954 | 0.00 | 16 | 1/1 mines reporting |
| 2025 Q2 | 0 | 10,060 | 0.00 | 16 | 1/1 mines reporting |
| 2025 Q3 | 0 | 7,656 | 0.00 | 20 | 1/1 mines reporting |
| 2025 Q4 | 0 | 7,787 | 0.00 | 20 | 1/1 mines reporting |
| 2026 Q1 | 0 | 8,738 | 0.00 | 17 | 1/1 mines reporting |
| 2026 Q2 | 0 | 9,239 | 0.00 | 18 | 1/1 mines reporting |
| 2026 Q3 | — | — | — | — | No report |
| 2026 Q4 | — | — | — | — | No report |
Safety and enforcement
2025-01-01 – 2026-10-13
Violations
60 significant & substantial (S&S)
Accident records
00 records classified as fatality
Proposed penalties · USD
679.004 of 6 violations with amounts
On-site inspection hours
44.003 inspections · 3 with hours
Counts are published records, including contractor records. * The quarter was incomplete at the snapshot date; recent counts may rise as reports arrive. — means no reported amount or hours. Portfolio totals use current membership.
Quarterly safety data
| Quarter | Violations | S&S | Proposed USD | Accident records | Fatality records | Inspections | On-site hours |
|---|---|---|---|---|---|---|---|
| 2025-Q1 | 0 | 0 | — | 0 | 0 | 0 | — |
| 2025-Q2 | 0 | 0 | — | 0 | 0 | 0 | — |
| 2025-Q3 | 3 | 0 | 528.00 | 0 | 0 | 1 | 17.0 |
| 2025-Q4 | 1 | 0 | 151.00 | 0 | 0 | 1 | 9.3 |
| 2026-Q1 | 0 | 0 | — | 0 | 0 | 0 | — |
| 2026-Q2 | 0 | 0 | — | 0 | 0 | 0 | — |
| 2026-Q3 | 2 | 0 | — | 0 | 0 | 1 | 17.8 |
| 2026-Q4 * | 0 | 0 | — | 0 | 0 | 0 | — |
Most cited CFR sections
All violations issued in the selected period. Counts combine subsections.
Safety activity
56.20003(c)
56.14107(a)
Regular Safety and Health Inspection · 17.8 on-site hours
Regular Safety and Health Inspection · 9.3 on-site hours
56.14100(b) · $151.00 proposed
62.170(a)(3) · $151.00 proposed
56.12004 · $226.00 proposed
56.12004 · $151.00 proposed
Regular Safety and Health Inspection · 17.0 on-site hours
Safety sources and definitions
MSHA Violations (issue date), Accidents (accident date), and Inspections (begin date). Snapshot 2026-10-13.
Counts describe published rows, including contractor records; accident records are not distinct incidents or numbers of people injured.
Zero means no matching records in the imported sources, not proof of no events. Historical coverage differs by source; absence before a source begins reporting is not a zero incident rate. Invalid or absent dates and records after the snapshot are excluded.
S&S means SIG_SUB=Y. Fatality records use DEGREE_INJURY_CD=01. Proposed penalties are not final assessed or paid amounts; missing dollar values are omitted.
Inspection hours are SUM_TOTAL_ON_SITE_HOURS attributed to the inspection start date, without supervisor/trainee hours. Missing hours are omitted; a started inspection may still be open.
Portfolio totals use current mine membership, including events before the current owner or operator's tenure.
CFR headings link to the current Title 30 index; they are not historical legal determinations.
OWNERSHIP
Operator and controller history
Current ownership comes from MSHA Mines. Historical start and end dates come from MSHA Controller and Operator History.
—
Martin Marietta Materials InccontrolsHanson Aggregates, Inc.operatesClayton Aggregates
msha-controller-operator-history · controller/operator co-tenure derived on mine 0400159—
Martin Marietta Materials InccontrolsMartin Marietta Northern California Aggregates,LLCoperatesClayton Aggregates
msha-controller-operator-history · controller/operator co-tenure derived on mine 0400159—
Heidelberg Materials AGcontrolsHanson Aggregates, Inc.operatesClayton Aggregates
msha-controller-operator-history · controller/operator co-tenure derived on mine 0400159—
Heidelberg Materials AGcontrolsMartin Marietta Northern California Aggregates,LLCoperatesClayton Aggregates
msha-controller-operator-history · controller/operator co-tenure derived on mine 0400159—
Hanson PLCcontrolsMartin Marietta Northern California Aggregates,LLCoperatesClayton Aggregates
msha-controller-operator-history · controller/operator co-tenure derived on mine 0400159—
Hanson PLCcontrolsHanson Aggregates West IncoperatesClayton Aggregates
msha-controller-operator-history · controller/operator co-tenure derived on mine 0400159—
Hanson PLCcontrolsHanson Aggregates, Inc.operatesClayton Aggregates
msha-controller-operator-history · controller/operator co-tenure derived on mine 0400159—
Koppers Company InccontrolsKaiser Sand & Gravel CompanyoperatesClayton Aggregates
msha-controller-operator-history · controller/operator co-tenure derived on mine 0400159Other historical summaries · source-specific periods
RECORD SUMMARY
Production, safety and enforcement
These summaries use the periods stated on each card, independently of the reporting period above.
01 / SAFETYwatch
Accidents and injuries
20 historical accident/injury rows; 0 coded fatalities and 808 lost days across the published record.
ACCIDENT + INJURY RECORD1 since 2021
accidentsmine-production-quarterly02 / COMPLIANCEwatch
Violations and penalties
202 violation rows across the full record; 36 carry an S&S flag and $42,083 appears in current assessed amounts.
ENFORCEMENT ACTIVITY24 since 2021
inspectionsviolationsassessed-violationsorders-107a03 / HEALTHcontext
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.
OCCUPATIONAL EXPOSURE21 samples
personal-health-samples04 / PRODUCTIONcontext
Quarterly production and employment
9K employee hours and 18 summed average employees across reported subunits in the latest published quarter.
2026-Q20 tons
mine-production-quarterlymine-production-yearly05 / LEGALwatch
Contests, conferences and decisions
19 contested-violation rows, 19 civil-penalty docket/decision rows, and 20 conference records linked by issuance number.
POST-ISSUANCE LIFECYCLE58 linked rows
conferencescontested-violationscivil-penalty-dockets-decisions06 / CONTRACTORScontext
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.
ENTITY-LEVEL CONTEXT11 linked entities
contractor-production-quarterlycontractor-production-yearlyaccidentsviolations07 / INSPECTIONScontext
Inspections
71 inspection events and 2K published inspection hours across the historical record.
OVERSIGHT COVERAGE14 since 2021
inspectionsviolationsHEALTH SAMPLING
Silica and quartz
Coal quartz, metal/nonmetal personal samples and area samples. Snapshot Oct 13, 2026. 4 silica records across the mine’s published history.
Personal silica samples · concentration / limit
Quarterly mean · published C/E ratio
— No eligible measurements. * Quarter in progress. Means describe the available samples, not average exposure across the mine.
Quartz % is the sample’s quartz content; µg/m³ is its reported concentration. Personal C/E is the ratio to the limit published with that sample. Personal and area concentration units and void status are not specified in those source files.
| Date / sample | Dataset / analyte | Occupation / area | Measurement | Sample status | Published action |
|---|---|---|---|---|---|
| 000000202603500800 | Metal/nonmetal personalQuartz, respirable, >1% Qtz | Laborer, Bullgang | 0× published limitConcentration: 0000.30 · limit: 0000.00Source unit unspecified | Not reported | NO ACTIONInspection F005BED |
Sources and interpretation
- Coal means use numeric concentrations from samples marked not voided, excluding control/invalid sample types and dates after the snapshot. Missing values remain null; reported zeroes remain zero.
- Quarterly means describe available samples, not mine-wide or worker-average exposure. Quarters with no eligible measurements remain empty; the current quarter is partial.
- Personal C/E is MSHA's published concentration-to-limit ratio. A value above 1 is not by itself a citation or a determination under the 2024 silica rule. Personal and area files do not publish a void-status field.
- Area records include bulk-dust analyses and are kept separate from personal exposure results. Their concentration units are not specified in the source dictionary.
- Missing samples do not establish safe conditions. Coal quartz percentage and concentration are separate measures. No compliance threshold is inferred for coal samples.
Coal quartz field definitions ↗Metal/nonmetal personal field definitions ↗Metal/nonmetal area field definitions ↗
EIA + TITLE 30
EIA production and cited regulations
EIA annual figures are reported separately from MSHA. Regulation links use the current eCFR snapshot.
Not present in the 2024 EIA coal workbook.
This can mean the operation is non-coal, inactive for the annual period, or outside the EIA-7A reporting population.
30 CFR 56.20003Housekeeping.1 recent row ↗30 CFR 56.14107Moving machine parts.1 recent row ↗30 CFR 56.14100Safety defects; examination, correction and records.1 recent row ↗30 CFR 62.170Audiometric testing.1 recent row ↗30 CFR 56.12004Electrical conductors.2 recent rows ↗30 CFR 56.13015Inspection of compressed-air receivers and other unfired pressure vessels.2 recent rows ↗30 CFR 41.12Changes; notification by operator.1 recent row ↗30 CFR 56.11027Scaffolds and working platforms.1 recent row ↗
RECENT PUBLIC RECORDS
Recent violations and samples
Latest records retained for inspection; aggregates above use the full source history.
510245956.20003(c)Citation
510245856.14107(a)Citation
999959856.14100(b)Citation
510229262.170(a)(3)Citation
510229156.12004Citation
510229056.12004Citation
968934956.13015Citation
968934856.13015Citation
Coal dust, noise and other contaminants. Silica records above ↑
Respirable dust, <.1mgMechanic
C/E: 00.00Concentration: 0000.00 · limit: 0000.00Source unit unspecified
Respirable dust, <.1mgLaborer, Bullgang
C/E: 00.00Concentration: 0000.00 · limit: 0000.00Source unit unspecified
Respirable dust, <.1mgLaborer, Bullgang
C/E: 00.00Concentration: 0000.00 · limit: 0000.00Source unit unspecified
Unlisted Particulate, respirable, <1% QtzLaborer, Bullgang
C/E: 00.00Concentration: 0000.49 · limit: 0000.00Source unit unspecified
Unlisted Particulate, respirable, <1% QtzLaborer, Bullgang
C/E: 00.00Concentration: 0000.18 · limit: 0000.00Source unit unspecified
Respirable dust, <.1mgTruck Driver
C/E: 00.00Concentration: 0000.00 · limit: 0000.00Source unit unspecified
Respirable dust, <.1mgDry Screen Plant Operator
C/E: 00.00Concentration: 0000.00 · limit: 0000.00Source unit unspecified
Unlisted Particulate, respirable, <1% QtzLaborer, Bullgang
C/E: 00.00Concentration: 0000.83 · limit: 0000.00Source unit unspecified
SOURCE COVERAGE
Reporting dates and coverage
15 datasets contain linked records. Missing datasets are listed below.
DATASETROWSWINDOWSTATUS
Accident, Injuries, and Illnessessafety · contractors20Mar 27, 2000—Dec 15, 2021mine-keyed
Addresses of Recordidentity · logistics1Jul 25, 1973—Jul 25, 1973mine-keyed
Assessed Violationscompliance · legal198Jun 23, 2000—Oct 8, 2025mine-keyed
Civil Penalty Dockets and Decisionscompliance · legal19Jun 16, 2009—Feb 26, 2015mine-keyed
Coal Dust Sampleshealth · safety—No published rowsabsent / not applicable
Conferencescompliance · legal20Feb 17, 2006—Feb 2, 2015mine-keyed
Contested Violationscompliance · legal19May 19, 2008—Jun 26, 2014mine-keyed
Contractor Employment and Production — Quarterlycontractors · production · safety999Not published—Not publishedentity-linked
Contractor Employment and Production — Yearlycontractors · production · safety223Not published—Not publishedentity-linked
Controller and Operator Historyidentity · compliance8Jan 1, 1978—Dec 9, 2005mine-keyed
Mine Employment and Production — Quarterlyproduction · safety · compliance257Not published—Not publishedmine-keyed
Mine Employment and Production — Yearlyproduction · safety · compliance54Not published—Not publishedmine-keyed
Inspectionssafety · compliance71Jun 22, 2000—Aug 21, 2026mine-keyed
Minesidentity · production · logistics1Not published—Not publishedmine-keyed
Metal and Nonmetal Area Sampleshealth · safety—No published rowsabsent / not applicable
Metal and Nonmetal Personal Health Sampleshealth · safety21Jun 24, 2004—Aug 26, 2026mine-keyed
Noise Sampleshealth · safety · equipment—No published rowsabsent / not applicable
Quartz Samples — Coalhealth · safety—No published rowsabsent / not applicable
Violationscompliance · safety · legal202Jun 23, 2000—Aug 25, 2026mine-keyed
107(a) Orders Issuedsafety · compliance—No published rowsabsent / not applicable
NOTES
Limitations
- Contractor production is entity-level and is never represented as mine-attributable.
- Missing rows can mean no event, publication delay, identity mismatch, or inapplicability.