MINE DETAILS
Mojave Plant & Quarry
MSHA MINE ID0400036
LOCATION
Mine location
1 of 1 mine with usable MSHA coordinates. Select a marker to open a mine.
Mine coordinates
- Mojave Plant & Quarry35.03833, -118.29472Open 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
511,407reported 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 | 133,274 | 0.00 | 127 | 1/1 mines reporting |
| 2025 Q2 | 0 | 69,054 | 0.00 | 152 | 1/1 mines reporting |
| 2025 Q3 | 0 | 79,418 | 0.00 | 152 | 1/1 mines reporting |
| 2025 Q4 | 0 | 79,610 | 0.00 | 152 | 1/1 mines reporting |
| 2026 Q1 | 0 | 72,632 | 0.00 | 154 | 1/1 mines reporting |
| 2026 Q2 | 0 | 77,419 | 0.00 | 156 | 1/1 mines reporting |
| 2026 Q3 | — | — | — | — | No report |
| 2026 Q4 | — | — | — | — | No report |
Safety and enforcement
2025-01-01 – 2026-10-13
Violations
8918 significant & substantial (S&S)
Accident records
60 records classified as fatality
Proposed penalties · USD
55,030.0087 of 89 violations with amounts
On-site inspection hours
391.7510 inspections · 10 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 | 14 | 2 | 3,354.00 | 0 | 0 | 1 | 59.8 |
| 2025-Q2 | 18 | 4 | 3,699.00 | 1 | 0 | 3 | 91.8 |
| 2025-Q3 | 1 | 0 | — | 1 | 0 | 1 | 28.5 |
| 2025-Q4 | 26 | 5 | 30,575.00 | 1 | 0 | 3 | 95.8 |
| 2026-Q1 | 0 | 0 | — | 1 | 0 | 0 | — |
| 2026-Q2 | 30 | 7 | 17,402.00 | 2 | 0 | 2 | 116.0 |
| 2026-Q3 | 0 | 0 | — | 0 | 0 | 0 | — |
| 2026-Q4 * | 0 | 0 | — | 0 | 0 | 0 | — |
Most cited CFR sections
All violations issued in the selected period. Counts combine subsections.
Safety activity
Spot Inspection · 0.0 on-site hours
56.18020 · $209.00 proposed
ENTRAPMENT · ACCIDENT ONLY
Accident narrative
Elevator stopped between floors with two miners on board.
HANDLING OF MATERIALS · ALL OTHER CASES (INCL 1ST AID)
Accident narrative
Miner was on foot scouting a new drill pattern. EE bent to pick up EE's wheel chocks and felt a muscle pull in EE's back muscles.
56.14112(a)(1) · $151.00 proposed
56.15005 · S&S · $959.00 proposed
56.4402 · $151.00 proposed
50.30(a) · $151.00 proposed
56.12004 · $193.00 proposed
47.41(a) · $151.00 proposed
56.12032 · $151.00 proposed
56.12032 · $151.00 proposed
56.4201(a)(2) · $151.00 proposed
50.30(a) · $151.00 proposed
56.14100(c) · S&S · $3,184.00 proposed
56.12032 · $151.00 proposed
46.8 · $168.00 proposed
46.3(b) · $151.00 proposed
50.30(a) · $151.00 proposed
50.30(a) · $151.00 proposed
50.30(a) · $151.00 proposed
46.11(b)(5) · S&S · $4,152.00 proposed
56.20003(a) · S&S · $755.00 proposed
56.20003(a) · S&S · $1,679.00 proposed
47.41(a) · $151.00 proposed
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.
—
Taiheiyo Cement CorpcontrolsCalportlandoperatesMojave Plant & Quarry
msha-controller-operator-history · controller/operator co-tenure derived on mine 0400036—
Calmat CompanycontrolsCalifornia Portland Cement CompanyoperatesMojave Plant & Quarry
msha-controller-operator-history · controller/operator co-tenure derived on mine 0400036—
California Portland Cement CompanycontrolsCalifornia Portland Cement CompanyoperatesMojave Plant & Quarry
msha-controller-operator-history · controller/operator co-tenure derived on mine 0400036Other 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
252 historical accident/injury rows; 1 coded fatalities and 5,119 lost days across the published record.
ACCIDENT + INJURY RECORD40 since 2021
accidentsmine-production-quarterly02 / COMPLIANCEwatch
Violations and penalties
988 violation rows across the full record; 294 carry an S&S flag and $580,786 appears in current assessed amounts.
ENFORCEMENT ACTIVITY367 since 2021
inspectionsviolationsassessed-violationsorders-107a03 / HEALTHwatch
Occupational health samples
86 personal; 3 area. 3 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 EXPOSURE89 samples
personal-health-samplesarea-samples04 / PRODUCTIONcontext
Quarterly production and employment
77K employee hours and 156 summed average employees across reported subunits in the latest published quarter.
2026-Q20 tons
mine-production-quarterlymine-production-yearly05 / LEGALwatch
Contests, conferences and decisions
55 contested-violation rows, 56 civil-penalty docket/decision rows, and 37 conference records linked by issuance number.
POST-ISSUANCE LIFECYCLE148 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 CONTEXT46 linked entities
contractor-production-quarterlycontractor-production-yearlyaccidentsviolations07 / INSPECTIONScontext
Inspections
154 inspection events and 8K published inspection hours across the historical record.
OVERSIGHT COVERAGE39 since 2021
inspectionsviolationsHEALTH SAMPLING
Silica and quartz
Coal quartz, metal/nonmetal personal samples and area samples. Snapshot Oct 13, 2026. 17 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 |
|---|---|---|---|---|---|
| 000000202601673200 | Metal/nonmetal personalQuartz, respirable, >1% Qtz | Front-end Loader Operator | 0× published limitConcentration: 0000.18 · limit: 0000.00Source unit unspecified | Not reported | NO ACTIONInspection F039E24 |
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 56.18020Working alone.1 recent row ↗30 CFR 56.14112Construction and maintenance of guards.1 recent row ↗30 CFR 56.15005Safety belts and lines.1 recent row ↗30 CFR 56.4402Safety can use.1 recent row ↗30 CFR 50.30Preparation and submission of MSHA Form 7000-2—Quarterly Employment and Coal Production Report.2 recent rows ↗30 CFR 56.12004Electrical conductors.1 recent row ↗30 CFR 47.41Requirement for container labels.1 recent row ↗30 CFR 56.12032Inspection and cover plates.2 recent rows ↗
RECENT PUBLIC RECORDS
Recent violations and samples
Latest records retained for inspection; aggregates above use the full source history.
516529356.18020Citation
516627256.14112(a)(1)Citation
516664656.15005S&S
516627156.4402Citation
516627050.30(a)Citation
516664556.12004Citation
516626947.41(a)Citation
516664456.12032Citation
Coal dust, noise and other contaminants. Silica records above ↑
Respirable dust, <.1mgCrusher Oper/Worker
C/E: 00.00Concentration: 0000.00 · limit: 0000.00Source unit unspecified
Nuisance dust, respirable, <1% QtzMechanic
C/E: 00.05Concentration: 0000.50 · limit: 0010.00Source unit unspecified
Nuisance dust, respirable, <1% QtzLaborer, Bullgang
C/E: 00.10Concentration: 0000.97 · limit: 0010.00Source unit unspecified
Respirable dust, <.1mgTruck Driver
C/E: 00.00Concentration: 0000.00 · limit: 0000.00Source unit unspecified
Respirable dust, <.1mgElectrician
C/E: 00.00Concentration: 0000.00 · limit: 0000.00Source unit unspecified
Respirable dust, <.1mgMechanic
C/E: 00.00Concentration: 0000.00 · limit: 0000.00Source unit unspecified
Respirable dust, <.1mgBagging Operator
C/E: 00.00Concentration: 0000.00 · limit: 0000.00Source unit unspecified
Nuisance dust, respirable, <1% QtzUtility Man
C/E: 00.07Concentration: 0000.73 · limit: 0010.00Source unit unspecified
SOURCE COVERAGE
Reporting dates and coverage
16 datasets contain linked records. Missing datasets are listed below.
DATASETROWSWINDOWSTATUS
Accident, Injuries, and Illnessessafety · contractors252Jan 1, 2000—Jun 17, 2026mine-keyed
Addresses of Recordidentity · logistics1Apr 10, 1975—Apr 10, 1975mine-keyed
Assessed Violationscompliance · legal978May 2, 2000—Jun 22, 2026mine-keyed
Civil Penalty Dockets and Decisionscompliance · legal56May 7, 2002—May 8, 2025mine-keyed
Coal Dust Sampleshealth · safety—No published rowsabsent / not applicable
Conferencescompliance · legal37Oct 22, 2001—Mar 7, 2025mine-keyed
Contested Violationscompliance · legal55Feb 20, 2008—Apr 15, 2026mine-keyed
Contractor Employment and Production — Quarterlycontractors · production · safety4,736Not published—Not publishedentity-linked
Contractor Employment and Production — Yearlycontractors · production · safety986Not published—Not publishedentity-linked
Controller and Operator Historyidentity · compliance3Jan 1, 1950—Oct 1, 1990mine-keyed
Mine Employment and Production — Quarterlyproduction · safety · compliance318Not published—Not publishedmine-keyed
Mine Employment and Production — Yearlyproduction · safety · compliance81Not published—Not publishedmine-keyed
Inspectionssafety · compliance154May 2, 2000—Jun 22, 2026mine-keyed
Minesidentity · production · logistics1Not published—Not publishedmine-keyed
Metal and Nonmetal Area Sampleshealth · safety3Aug 11, 2004—Jun 23, 2009mine-keyed
Metal and Nonmetal Personal Health Sampleshealth · safety86Oct 3, 2001—Apr 23, 2026mine-keyed
Noise Sampleshealth · safety · equipment—No published rowsabsent / not applicable
Quartz Samples — Coalhealth · safety—No published rowsabsent / not applicable
Violationscompliance · safety · legal988May 2, 2000—Jun 22, 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.