Diablo Plant # 136 has $12K in proposed MSHA penalties and $0 outstanding across 0 contested dockets, plus health sampling and the full incident record.
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Fatalities
0
Total incidents
3
Years on record
2015–2017
Latest incident
Apr 2017
Compliance record
MSHA citations since 2015
57
citations
10
significant & substantial
$11,988
proposed penalties
$11,988
paid to date
100% of proposed penalties paid to date, a $0 gap.
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.
Rate withheld: 495 inspection hours is too few for a stable rate. A minimum of 1,000 inspection hours is required.
Source: MSHA inspections data, updated weekly.
Diablo Plant # 136 has $12K in proposed MSHA penalties and $0 outstanding across 0 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.
$12K
proposed penalties
$12K
current assessed
$12K
paid to date
$0
outstanding
57 assessments are final orders; 0 contested dockets.
As of the most recent assessment on 2026-03-17.
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.
Source: MSHA violations gravity and negligence coding, 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: 2024-09-24
20%
of limit-tested samples over the exposure limit
22
samples
5
limit-tested
Most sampled contaminants
Quartz, respirable, >1% Qtz41 over
Respirable dust, <.1mg17
Nuisance dust, respirable, <1% Qtz1
Show the individual readings (22)
Date
Contaminant
Concentration
Limit
Conc / limit
Occupation
2016-10-20
Quartz, respirable, >1% Qtz
0.81
0.63
1.29
Crusher Oper/Worker
2024-09-24
Respirable dust, <.1mg
0
Washer Operator
2024-09-24
Quartz, respirable, >1% Qtz
0.16
0.77
0.21
Mechanic
2024-09-24
Respirable dust, <.1mg
0
Bulldozer Operator
2024-09-24
Quartz, respirable, >1% Qtz
0.17
0.83
0.20
Crusher Oper/Worker
2022-09-27
Respirable dust, <.1mg
0
Front-end Loader Operator
2022-09-27
Nuisance dust, respirable, <1% Qtz
0.14
10
0.01
Washer Operator
2022-09-27
Respirable dust, <.1mg
0
Crusher Oper/Worker
2022-09-27
Respirable dust, <.1mg
0
Front-end Loader Operator
2019-10-17
Respirable dust, <.1mg
0
Front-end Loader Operator
2019-10-17
Respirable dust, <.1mg
0
Crusher Oper/Worker
2019-10-17
Respirable dust, <.1mg
0
Washer Operator
2019-10-17
Respirable dust, <.1mg
0
Front-end Loader Operator
2018-10-30
Respirable dust, <.1mg
0
Front-end Loader Operator
2018-10-30
Respirable dust, <.1mg
0
Front-end Loader Operator
2018-05-03
Respirable dust, <.1mg
0
Crusher Oper/Worker
2018-05-03
Respirable dust, <.1mg
0
Front-end Loader Operator
2016-12-20
Quartz, respirable, >1% Qtz
0.16
0.73
0.22
Crusher Oper/Worker
2016-10-20
Respirable dust, <.1mg
0
Front-end Loader Operator
2015-11-05
Respirable dust, <.1mg
0
Crusher Oper/Worker
2015-11-05
Respirable dust, <.1mg
0
Front-end Loader Operator
2015-11-05
Respirable dust, <.1mg
0
Front-end Loader Operator
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.
Diablo Plant # 136 recorded 0.00 reportable injury cases per 100 full-time workers in 2025.
Injury rate, 2025
ⓘ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.
0.00
total case rate
0.00
days-away rate
0.000
fatality rate
Below average. The US metal and nonmetal mining average was 1.65 and the all-US-mining average was 1.97 cases per 100 workers.
In Arizona, metal and nonmetal mining averaged 1.81 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
2025 *
0.00
0.00
0.000
2024 *
0.00
0.00
0.000
2023 *
0.00
0.00
0.000
2022 *
0.00
0.00
0.000
2021 *
0.00
0.00
0.000
2020 *
0.00
0.00
0.000
2017 *
9.79
9.79
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.
Source: MSHA controller and operator history, updated weekly.
Workforce and production
Year
Employees
2026
9
2025
13
2024
9
2023
9
2022
9
2021
8
2020
7
2019
7
2018
8
2017
8
2016
8
2015
6
Source: MSHA quarterly employment and production, updated weekly.
Diablo Plant # 136 sits in Pinal County, Arizona, where the Census mining category is 0.8% 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.
Pinal County, Arizona · Population 449,219
0.8%
Mining share of county employment
$77,588
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
2,744
0
0
0.0
2026 Q1
6,073
7
0
1152.6
2025 Q4
5,990
0
0
0.0
2025 Q3
6,286
1
0
159.1
2025 Q2
7,527
0
0
0.0
2025 Q1
7,043
0
0
0.0
2024 Q4
6,963
0
0
0.0
2024 Q3
7,748
0
0
0.0
Show 38 earlier quartersHide earlier quarters
Quarter
Hours worked
Citations
S&S
Per 1M hrs
2024 Q2
9,128
0
0
0.0
2024 Q1
7,508
0
0
0.0
2023 Q4
8,203
0
0
0.0
2023 Q3
8,199
0
0
0.0
2023 Q2
7,081
1
1
141.2
2023 Q1
6,508
0
0
0.0
2022 Q4
5,963
4
0
670.8
2022 Q3
4,304
0
0
0.0
2022 Q2
6,452
0
0
0.0
2022 Q1
7,698
1
1
129.9
2021 Q4
4,162
0
0
0.0
2021 Q3
5,251
3
0
571.3
2021 Q2
5,392
0
0
0.0
2021 Q1
5,270
0
0
0.0
2020 Q4
5,210
4
0
767.8
2020 Q3
5,293
0
0
0.0
2020 Q2
5,360
0
0
0.0
2020 Q1
5,542
0
0
0.0
2019 Q4
5,373
4
0
744.5
2019 Q3
4,429
0
0
0.0
2019 Q2
4,779
0
0
0.0
2019 Q1
4,894
0
0
0.0
2018 Q4
3,609
2
0
554.2
2018 Q3
5,491
0
0
0.0
2018 Q2
4,931
3
0
608.4
2018 Q1
4,834
0
0
0.0
2017 Q4
4,792
5
0
1043.4
2017 Q3
4,988
0
0
0.0
2017 Q2
5,462
6
2
1098.5
2017 Q1
5,186
0
0
0.0
2016 Q4
5,193
9
3
1733.1
2016 Q3
4,926
0
0
0.0
2016 Q2
4,867
0
0
0.0
2016 Q1
4,197
0
0
0.0
2015 Q4
4,266
6
2
1406.5
2015 Q3
2,861
0
0
0.0
2015 Q2
2,791
0
0
0.0
2015 Q1
228
0
0
0.0
No fatalities recorded at this mine.
Reportable incidents
3 on file
2017 · 1 incident
April 7, 2017AZ · Metal/Non-Metalbulldozer operator, universal operator, heavy equipment operator, operating engineerHANDLING OF MATERIALS
EE was moving a piece of plate steel to gain access to timber to place under load of new steel shipment. EE lifted the approximately 3' x 5' by 3/8 inch steel the long way and pushed over to the side 180 degrees. The steel plate hit an approximately 18" high steel beam and kicked back striking the EE's heel causing EE's heel bone to break in hairline fractures
2016 · 1 incident
November 18, 2016AZ · Metal/Non-Metalmaintenance man, mechanic, repair/serviceman, boilermaker, fueler, tire tech, field service techHANDLING OF MATERIALS
CalPortland Company · Caught in, under or between a moving and a stationary object
Employee used poor hand placement while getting off of VSI lid EE was repairing. Employee was also not wearing gloves during the time of injury. Poor hand placement on pivot point while getting off of equipment caused left pinky to get caught between VSI lid and attach point. The result was employee fracturing the tip of the right pinky finger.
CalPortland Company · Caught in, under or between a moving and a stationary object
Employee was removing a broken impeller from pump shaft. A cheater bar was connected to a wrench when the wrench slipped and the employee fell to the ground and his hand was caught between cheater bar and the concrete pad, fracturing the right ring finger.