Mining Incidents

Santa Margarita Aggregates: 163 MSHA citations Metal/Non-Metal

Santa Margarita, San Luis Obispo County, CA  ·  Active
MSHA Mine ID: 0401616

Santa Margarita Aggregates has $104K in proposed MSHA penalties and $0 outstanding across 1 contested dockets, plus health sampling and the full incident record.

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Fatalities
0
Total incidents
24
Years on record
1986–2022
Latest incident
Aug 2022
Compliance record
MSHA citations since 2001
163
citations
42
significant & substantial
$103,842
proposed penalties
$103,493
paid to date
100% of proposed penalties paid to date, a $349 gap.
Source: MSHA violations data, updated weekly.
Inspection activity
MSHA inspections since 2001
72
inspections on record
1,434
inspection hours
11.4
citations per 100 inspection hours
This rate is recorded citations divided by MSHA inspection hours, per 100 hours. It reflects inspection effort, not mine size or production.
163 citations across 1,434 inspection hours.
Source: MSHA inspections data, updated weekly.

Santa Margarita Aggregates has $104K in proposed MSHA penalties and $0 outstanding across 1 contested dockets.

Penalty disposition
Differences between proposed and paid penalties reflect both settlements and conference reductions and amounts still owed. Outstanding is the balance currently owed.
$104K
proposed penalties
$103K
current assessed
$103K
paid to date
$0
outstanding
162 assessments are final orders; 1 contested dockets.
Of $934 in penalties contested before the Commission, $485 was upheld in final decisions.
As of the most recent assessment on 2026-04-27.
Source: MSHA assessed-violations and conference/litigation data, updated weekly.
Violation severity profile
Shares are computed over citations that carry the MSHA gravity and negligence coding; a small share of records are uncoded.
25.8%
significant & substantial
16.0%
high negligence or reckless
25.8%
reasonably likely or greater
50.3%
permanently disabling or fatal if injury occurs
Negligence coding: 0.0% none, 17.8% low, 66.3% moderate, 16.0% high, 0.0% reckless.
Source: MSHA violations gravity and negligence coding, updated weekly.
When citations were contested
Contesting a citation before the Federal Mine Safety and Health Review Commission is a lawful right. These figures state the public outcomes of that process, from MSHA's Contested Violations file.
4 citations taken to the federal commission · 2% of citations on record
  • Settled 3 · 75%
  • Vacated or withdrawn 1 · 25%
0%
S&S designation survived the contest
Counts a Significant & Substantial citation as surviving when a settlement or judge's decision kept the designation, or the contest was dismissed or defaulted so the citation stands as issued. Vacated and withdrawn citations, and settlements that removed the designation, count against.
of 1 decided S&S contests · industry: 79%
48%
Penalty reduction in decided contests
$934 proposed, $485 after decisions · industry: 39%
Source: MSHA Contested Violations file (public record), updated weekly. A dismissed or defaulted contest leaves the citation standing as issued; a vacated or withdrawn citation is removed from the violation record. Latest contest filed 2010-03-10.
Contested penalties
A reduction or dismissal at the Commission is a lawful outcome of contesting a proposed penalty. Figures are the proposed amount and the amount upheld in the docket's decision.
Largest penalties this mine contested before the Federal Mine Safety and Health Review Commission, with the outcome on record.
Docket Decision Judge Year Proposed / upheld
WEST 2010-808M Settlement Gill 2011 $934 → $485
Source: FMSHRC civil penalty dockets and decisions (public record), updated weekly.
Health sampling
A sample is a point in time compliance measurement, not an individual exposure history. These figures describe MSHA sampling records and do not establish causation or personal dose.

Metal and nonmetal contaminants (personal samples)
Many samples are screening measurements of substances with no applicable exposure limit; they are counted as samples but excluded from every over-limit figure. Over-limit shares use only limit-tested samples.

Last sampled: 2026-04-27
0%
of limit-tested samples over the exposure limit
21
samples
12
limit-tested
Most sampled contaminants
  • Quartz, respirable, >1% Qtz13
  • Respirable dust, <.1mg8
Show the individual readings (21)
Date Contaminant Concentration Limit Conc / limit Occupation
2026-04-27 Respirable dust, <.1mg 0 Laborer, Bullgang
2022-11-30 Quartz, respirable, >1% Qtz 0.15 Laborer, Bullgang
2022-11-30 Quartz, respirable, >1% Qtz 0.53 0.57 0.93 Laborer, Bullgang
2022-05-04 Quartz, respirable, >1% Qtz 0.17 0.47 0.36 Crusher Oper/Worker
2019-02-04 Respirable dust, <.1mg 0 Front-end Loader Operator
2015-10-20 Respirable dust, <.1mg 0 Crusher Oper/Worker
2015-10-20 Quartz, respirable, >1% Qtz 0.43 1.22 0.35 Washer Operator
2015-10-20 Quartz, respirable, >1% Qtz 0.14 0.69 0.20 Truck Driver
2015-10-20 Quartz, respirable, >1% Qtz 0.12 1.02 0.12 Dry Screen Plant Operator
2015-10-20 Respirable dust, <.1mg 0 Front-end Loader Operator
2009-05-13 Respirable dust, <.1mg 0 Truck Driver
2009-05-13 Quartz, respirable, >1% Qtz 0.17 0.62 0.27 Truck Driver
2009-05-13 Respirable dust, <.1mg 0 Front-end Loader Operator
2009-05-13 Quartz, respirable, >1% Qtz 0.3 0.75 0.40 Washer Operator
2005-04-20 Quartz, respirable, >1% Qtz 0.23 0.47 0.49 Front-end Loader Operator
2005-04-20 Respirable dust, <.1mg 0 Truck Driver
2005-04-20 Quartz, respirable, >1% Qtz 0.38 0.75 0.51 Truck Driver
2005-04-20 Respirable dust, <.1mg 0 Washer Operator
2004-01-28 Quartz, respirable, >1% Qtz 0.16 0.84 0.19 Crusher Oper/Worker
2004-01-28 Quartz, respirable, >1% Qtz 0.24 0.85 0.28 Oiler, Greaser
2004-01-28 Quartz, respirable, >1% Qtz 0.23 1.62 0.14 Crusher Oper/Worker
Source: MSHA respirable dust, quartz, and noise sampling records, updated weekly. Metal/nonmetal contaminant figures come from MSHA's Personal Health Samples and Area Samples files (public record), updated weekly.

Santa Margarita Aggregates recorded 6.78 reportable injury cases per 100 full-time workers in 2022.

Injury rate, 2022
This rate is reportable injury cases per 100 full-time-equivalent workers per year, computed as 200,000 times cases divided by MSHA operator-reported employee-hours. Cases are injuries MSHA graded degree 01 through 07; accident-only events that hurt no one are excluded, and so are contractor injuries, whose hours do not attach to a single mine. Rates begin in 2000, when quarterly employment reporting starts, and are withheld below 20,000 hours in a year.
6.78
total case rate
0.00
days-away rate
0.000
fatality rate
Above average. The US metal and nonmetal mining average was 1.78 and the all-US-mining average was 2.12 cases per 100 workers.
In California, metal and nonmetal mining averaged 1.91 cases per 100 workers that year.
Under 100,000 employee-hours were reported that year, so a single case moves the rate by two or more. Read the figure as approximate.
Year total case rate days-away fatal
2022 * 6.78 0.00 0.000
2021 * 5.43 5.43 0.000
2020 * 0.00 0.00 0.000
2019 * 0.00 0.00 0.000
2018 * 0.00 0.00 0.000
2017 * 7.81 0.00 0.000
2016 * 0.00 0.00 0.000
2015 * 15.58 0.00 0.000
* Fewer than 100,000 employee-hours that year; the rate is less stable.
Source: injury cases from MSHA accident and injury records; employee-hours from MSHA quarterly employment reports. Rate is cases per 100 full-time-equivalent workers, operator employees only.
Ownership history
  1. Kaiser Sand & Gravel Company 1978 to 1988
  2. Hanson Aggregates West Inc 1988 to 2006
  3. Martin Marietta Northern California Aggregates,LLC 2006 to present
Source: MSHA controller and operator history, updated weekly.
Workforce and production
Year Employees
2026 10
2025 9
2024 8
2023 6
2022 12
2021 18
2020 14
2019 13
2018 14
2017 13
2016 15
2015 14
2014 16
2013 14
2012 13
2011 15
2010 15
2009 17
2008 15
2007 14
2006 14
2005 15
2004 16
2003 15
2002 16
2001 15
2000 17
Source: MSHA quarterly employment and production, updated weekly.

Santa Margarita Aggregates sits in San Luis Obispo County, California, where the Census mining category is 0.2% of county employment.

Local economic context
County figures come from the US Census Bureau's American Community Survey, 5-year pooled estimates, so the 2023 vintage covers 2019 through 2023. The Census category is 'mining, quarrying, and oil and gas extraction', which is broader than MSHA jurisdiction and includes oil and gas workers no mine employs. These figures describe the surrounding county, not this mine, and are not a factor in any specific incident.
San Luis Obispo County, California · Population 281,486
0.2%
Mining share of county employment
$93,398
Median household income
Source: US Census Bureau, American Community Survey 2023 5-year estimates.
Quarterly safety rates
Citations per million reported employee-hours. Rates begin in 2000, when MSHA's quarterly employment data starts; earlier incidents are counted but cannot be rate-adjusted. Quarters under 100,000 reported hours are greyed: too few hours for a stable rate.
Citations per million employee-hours, as reported to MSHA
Quarter Hours worked Citations S&S Per 1M hrs
2026 Q2 5,212 1 0 191.9
2026 Q1 6,171 1 0 162.0
2025 Q4 5,113 0 0 0.0
2025 Q3 3,916 2 0 510.7
2025 Q2 4,544 0 0 0.0
2025 Q1 4,460 0 0 0.0
2024 Q4 4,339 0 0 0.0
2024 Q3 4,597 0 0 0.0
Show 97 earlier quarters
Quarter Hours worked Citations S&S Per 1M hrs
2024 Q2 4,656 0 0 0.0
2024 Q1 4,961 2 1 403.1
2023 Q4 5,134 0 0 0.0
2023 Q3 2,838 0 0 0.0
2023 Q2 642 0 0 0.0
2023 Q1 3,808 0 0 0.0
2022 Q4 7,421 3 0 404.3
2022 Q3 7,136 0 0 0.0
2022 Q2 7,512 3 0 399.4
2022 Q1 7,447 5 3 671.4
2021 Q4 6,614 0 0 0.0
2021 Q3 13,928 0 0 0.0
2021 Q2 8,017 6 0 748.4
2021 Q1 8,279 7 0 845.5
2020 Q4 8,849 0 0 0.0
2020 Q3 7,821 6 2 767.2
2020 Q2 6,451 0 0 0.0
2020 Q1 7,500 8 6 1066.7
2019 Q4 6,860 0 0 0.0
2019 Q3 9,026 0 0 0.0
2019 Q2 6,984 9 7 1288.7
2019 Q1 6,860 1 1 145.8
2018 Q4 6,753 0 0 0.0
2018 Q3 7,808 0 0 0.0
2018 Q2 8,101 5 3 617.2
2018 Q1 6,653 3 2 450.9
2017 Q4 7,773 0 0 0.0
2017 Q3 6,126 0 0 0.0
2017 Q2 6,534 3 0 459.1
2017 Q1 5,182 3 1 578.9
2016 Q4 5,233 0 0 0.0
2016 Q3 6,488 0 0 0.0
2016 Q2 6,363 3 2 471.5
2016 Q1 5,625 0 0 0.0
2015 Q4 6,307 5 2 792.8
2015 Q3 5,615 0 0 0.0
2015 Q2 6,061 8 1 1319.9
2015 Q1 7,695 3 0 389.9
2014 Q4 7,648 0 0 0.0
2014 Q3 7,877 15 3 1904.3
2014 Q2 5,539 0 0 0.0
2014 Q1 6,305 0 0 0.0
2013 Q4 8,729 0 0 0.0
2013 Q3 6,775 0 0 0.0
2013 Q2 4,753 1 0 210.4
2013 Q1 5,397 0 0 0.0
2012 Q4 5,242 3 1 572.3
2012 Q3 5,763 0 0 0.0
2012 Q2 5,918 3 1 506.9
2012 Q1 6,786 5 2 736.8
2011 Q4 7,424 0 0 0.0
2011 Q3 8,107 1 1 123.4
2011 Q2 8,387 0 0 0.0
2011 Q1 7,962 3 0 376.8
2010 Q4 7,102 0 0 0.0
2010 Q3 7,716 1 1 129.6
2010 Q2 6,589 0 0 0.0
2010 Q1 5,155 3 0 582.0
2009 Q4 7,098 0 0 0.0
2009 Q3 7,806 0 0 0.0
2009 Q2 7,814 2 1 256.0
2009 Q1 8,231 0 0 0.0
2008 Q4 6,352 3 1 472.3
2008 Q3 6,375 0 0 0.0
2008 Q2 4,706 0 0 0.0
2008 Q1 6,374 2 0 313.8
2007 Q4 6,202 0 0 0.0
2007 Q3 6,183 0 0 0.0
2007 Q2 6,354 0 0 0.0
2007 Q1 6,156 0 0 0.0
2006 Q4 5,768 0 0 0.0
2006 Q3 5,901 2 0 338.9
2006 Q2 6,377 0 0 0.0
2006 Q1 6,926 7 0 1010.7
2005 Q4 5,804 0 0 0.0
2005 Q3 6,796 0 0 0.0
2005 Q2 6,050 0 0 0.0
2004 Q4 7,612 0 0 0.0
2004 Q3 6,637 0 0 0.0
2004 Q2 7,309 0 0 0.0
2004 Q1 6,761 3 0 443.7
2003 Q4 6,988 0 0 0.0
2003 Q3 7,335 1 0 136.3
2003 Q2 6,591 0 0 0.0
2003 Q1 6,631 3 0 452.4
2002 Q4 8,022 0 0 0.0
2002 Q3 7,776 3 0 385.8
2002 Q2 6,764 1 0 147.8
2002 Q1 7,075 0 0 0.0
2001 Q4 7,130 0 0 0.0
2001 Q3 5,972 4 0 669.8
2001 Q2 7,481 0 0 0.0
2001 Q1 6,467 3 0 463.9
2000 Q4 6,360 0 0 0.0
2000 Q3 8,040 0 0 0.0
2000 Q2 7,198 0 0 0.0
2000 Q1 7,530 0 0 0.0
No fatalities recorded at this mine.

Reportable incidents

24 on file

2022 · 1 incident

August 26, 2022 CA · Metal/Non-Metal bulldozer operator, universal operator, heavy equipment operator, operating engineer SLIP OR FALL OF PERSON
Martin Marietta Northern California Aggregates,LLC · Fall to the walkway or working surface

The employee had just finished the post-trip inspection of equipment they operated at the Santa Margarita Quarry. The employee wanted to check out the new frontend loader, so they started to walk around the and look at the new equipment. The new loader was backed into a cutout to prevent the equipment from moving and the employee stepped into the cutout and slipped and fell.

2021 · 1 incident

December 7, 2021 CA · Metal/Non-Metal bulldozer operator, universal operator, heavy equipment operator, operating engineer SLIP OR FALL OF PERSON
Martin Marietta Northern California Aggregates,LLC · Fall onto or against objects

Employee was cutting metal with a torch which was supported on sawhorses. The employee moved one sawhorse and continued to use the torch to cut the metal. The employee turned to make a step and tripped over the sawhorse that they had moved earlier. The employee fell and landed on their right shoulder.

2017 · 1 incident

June 27, 2017 CA · Metal/Non-Metal haul/off road/coal/ore/pit/quarry/rock/rubber tire truck driver, transportation truck driver MACHINERY
Martin Marietta Northern California Aggregates,LLC · Caught in, under or between running or meshing objects

Miner/employee was drilling a piece of angle iron in the area of the Feed tunnel belt area when the hand drill being used twisted in their right hand resulting in a sprain to their right ring finger. Miner/employee did not report or seek medical attention until 07/12/2017.

2015 · 2 incidents

September 30, 2015 CA · Metal/Non-Metal haul/off road/coal/ore/pit/quarry/rock/rubber tire truck driver, transportation truck driver HANDLING OF MATERIALS
Martin Marietta Northern California Aggregates,LLC · Caught in, under or between a moving and a stationary object

Employee received an open fracture on the tip of his left index finger while placing the main shaft sleeve on the crusher. His finger was caught between the main shaft sleeve and the mantle of the crusher when the lifting eye was removed before the sleeve was set in place and employee had not removed his finger. He required 3 stitches on the tip of his finger.

March 23, 2015 CA · Metal/Non-Metal maintenance man, mechanic, repair/serviceman, boilermaker, fueler, tire tech, field service tech HANDLING OF MATERIALS
Martin Marietta Northern California Aggregates,LLC · Caught in, under or between a moving and a stationary object

Employee and co-worker were moving steel bars onto the fork of a telelift. One bar slipped catching the employee's glove on a piece of broken weld causing his left thumb to be caught between 2 bars. Employee sustained a deep cut and a bone chipped in his left requiring 5 stitches, splint and medication.

2013 · 2 incidents

June 6, 2013 CA · Metal/Non-Metal haul/off road/coal/ore/pit/quarry/rock/rubber tire truck driver, transportation truck driver POWERED HAULAGE
Martin Marietta Northern California Aggregates,LLC · Struck against a moving object

Haul truck driver was dumping a load of rock at the stockpile. His telescopic hydraulic ram on the dump bed broke off at the 3rd stage causing the bed to slam down on the frame of truck, shaking driver giving him strained neck and shoulder muscles.

February 4, 2013 CA · Metal/Non-Metal warehouseman, bagger, palletizer/stacker, store keeper, packager, fabricator, cleaning plant operator OTHER

We are denying this claim. EE was on medical leave for COPD and he filed for Cal State Disability after his doctor told him his illness was not work related. After 2 months of not receiving any money from the State of California, he was told the claims are backed up. This is when he filed workman's compensation claim.

2010 · 1 incident

September 28, 2010 CA · Metal/Non-Metal water truck operator OTHER
Martin Marietta Northern California Aggregates,LLC · Absorption of radiations, caustics, toxic and noxious substances

While filling his water truck in the quarry, a bee stung the injured employee in the back of the neck.

2008 · 2 incidents

2007 · 1 incident

March 12, 2007 CA · Metal/Non-Metal front-end loader, scraper-loader operator, pan operator, payloader, scraper rig operator POWERED HAULAGE
Martin Marietta Northern California Aggregates,LLC · Caught in, under or between (Not Elsewhere Classified)

While cleaning out the dust from inside an air conditioning air vent deflector without turning the equipment off, the employee's finger was cut by a rotating blade.

2005 · 2 incidents

November 15, 2005 CA · Metal/Non-Metal haul/off road/coal/ore/pit/quarry/rock/rubber tire truck driver, transportation truck driver HANDTOOLS (NONPOWERED)
Hanson Aggregates West Inc · Over-exertion (Not Elsewhere Classified)

While tightening a bolt on a jaw crusher, the employee felt a twinge to his back.

September 26, 2005 CA · Metal/Non-Metal haul/off road/coal/ore/pit/quarry/rock/rubber tire truck driver, transportation truck driver POWERED HAULAGE
Hanson Aggregates West Inc · Struck against a moving object

Employee was being loaded. Loader backed up before bucket was clear. Truck leaned back then released, rocking it sideways causing injury to employee's back.

2004 · 1 incident

January 6, 2004 CA · Metal/Non-Metal front-end loader, scraper-loader operator, pan operator, payloader, scraper rig operator POWERED HAULAGE
Hanson Aggregates West Inc · Struck against a moving object

EMPLOYEE COMPLAINED OF BACK PAIN WHILE OPERATING #5114 LOADER.

1995 · 1 incident

February 17, 1995 CA · Metal/Non-Metal maintenance man, mechanic, repair/serviceman, boilermaker, fueler, tire tech, field service tech MACHINERY
Hanson Aggregates West Inc · Struck by... (Not Elsewhere Classified)

EE WAS DRESSING UP GEAR WITH DIE GRINDER WITH A THIN DISC ON GRINDER. WHILE HE WAS USING GRINDER AT FULL RPM, DISC EXPLODED AND CUT INTO HIS ARM.

1993 · 1 incident

May 24, 1993 CA · Metal/Non-Metal greaser, grease man, oiler, lube man, dragline oiler HANDTOOLS (NONPOWERED)
Hanson Aggregates West Inc · Struck by... (Not Elsewhere Classified)

EMPLOYEE WAS REMOVING CAST IRON WEAR PLATE THAT WAS WORN OUT PRYING UP WITH A SCREWDRIVER WHEN THE PLATE BROKE LOOSE & A SHARP EDGE OF WEAR PLATE LACERATED HIS FINGER.

1990 · 1 incident

June 8, 1990 CA · Metal/Non-Metal front-end loader, scraper-loader operator, pan operator, payloader, scraper rig operator HANDLING OF MATERIALS
Hanson Aggregates West Inc · Struck by falling object

EMPLOYEE WAS CARRYING HAMMER TO DRILL AND DROPPED ON HIS LEFT FOOT.

1989 · 3 incidents

July 25, 1989 CA · Metal/Non-Metal backhoe operator, trackhoe operator HANDLING OF MATERIALS
Hanson Aggregates West Inc · Struck by... (Not Elsewhere Classified)

EMPLOYEE WAS DISASSEMBLING SPRING LOADED BRAKE POD SHOT OFF AND HIT WATER TRUCK AND RICOCHETED OFF OF WATER TRUC AND HIT EMPLOYEE IN FACE.

May 31, 1989 CA · Metal/Non-Metal bulldozer operator, universal operator, heavy equipment operator, operating engineer SLIP OR FALL OF PERSON
Hanson Aggregates West Inc · Fall onto or against objects

EMPLOYEE WAS WALKING TO THE SUBBASE PLANT AND FELL ONTO A SHARP ROCK. THE ROCK CUT INTO HIS RIGHT KNEE.

February 8, 1989 CA · Metal/Non-Metal assayer, geologist, metallurgist, engineer, engineer management POWERED HAULAGE
Hanson Aggregates West Inc · Caught in, under or between a moving and a stationary object

EMPLOYEE WAS CLEANING DIR OFF RAIL OF FEEDER ROLLER WHILE MACHINE WAS OPERATING. INDEX FINGER SMASHED MIDDLE FINGER CUT OFF BEHIND NAIL.

1988 · 2 incidents

August 1, 1988 CA · Metal/Non-Metal assayer, geologist, metallurgist, engineer, engineer management HANDTOOLS (NONPOWERED)
Kaiser Sand & Gravel Company · Struck by... (Not Elsewhere Classified)

POUNDING PIECE OF STEEL INTO GROUND HE MISSED WITH HAMMER AND HIT IT HIS KNUCKLE OF RIGHT INDEX FINGER.

May 12, 1988 CA · Metal/Non-Metal haul/off road/coal/ore/pit/quarry/rock/rubber tire truck driver, transportation truck driver HANDTOOLS (NONPOWERED)
Kaiser Sand & Gravel Company · Struck by... (Not Elsewhere Classified)

RECEIVED GLANCING BLOW FROM SLEDGE HAMMER THAT GLANCEOFF OF BAR

1987 · 1 incident

June 26, 1987 CA · Metal/Non-Metal greaser, grease man, oiler, lube man, dragline oiler POWERED HAULAGE
Kaiser Sand & Gravel Company · Struck by powered moving object

WAS WASHING DOW3 THE LOADOUT AREA USING A LARGER HOSE.AS HE STEPPED BACKWARDS,HE STEPPED INTO THE PATH OF A QUARRY TRUCK AS IT LEFT THE LOADOUT AREA.

1986 · 1 incident

December 10, 1986 CA · Metal/Non-Metal haul/off road/coal/ore/pit/quarry/rock/rubber tire truck driver, transportation truck driver POWERED HAULAGE
Kaiser Sand & Gravel Company · Struck against a moving object

WEATHER WAS DAR5 AND FOGGY I NAME WAS BACKING A CAT TRUCK ON SAND STOCKPILE HE WAS TOO CLOSE TO EDGE ON HIS RT SIDE. BANK CAVED OFF AND TRUCK ROLLED OVER. I NAME HAD BUMPS AND BRUISES ALSO TORN CARTILAGE 3N RIGHT KNEE