OCS Study

BOEM 2020-050

US Department of the Interior

Bureau of Ocean Energy Management

Alaska Region

Oil Spill Occurrence Rates from Alaska 

North Slope Oil and Gas Exploration, 

Development, and Production
OCS Study

BOEM 2020-050

US Department of the Interior

Bureau of Ocean Energy Management

Alaska Region

Oil Spill Occurrence Rates from Alaska 

North Slope Oil and Gas Exploration, 

Development, and Production

October / 2020

Authors:

Tim Robertson, Nuka Research and Planning Group, Lead Author

Lynetta K. Campbell, Statistical Consulting Services, Lead Analyst

Sierra Fletcher, Nuka Research and Planning Group, Editor

Prepared under contract #140M0119F0003

by

Nuka Research and Planning Group, LLC

P.O. Box 175 Seldovia, AK 99663

10 Samoset Street Plymouth, Massachusetts 02360
i

DISCLAIMER

Study concept, oversight, and funding were provided by the US Department of the Interior, Bureau of 

Ocean Energy Management (BOEM), Environmental Studies Program, Washington, DC, under Contract 

Number 140M0119F0003. This report has been technically reviewed by BOEM, and it has been approved 

for publication. The views and conclusions contained in this document are those of the authors and should 

not be interpreted as representing the opinions or policies of the US Government, nor does mention of 

trade names or commercial products constitute endorsement or recommendation for use.

REPORT AVAILABILITY

To download a PDF file of this report, go to the US Department of the Interior, Bureau of Ocean Energy 

Management Data and Information Systems webpage (http://www.boem.gov/Environmental-StudiesEnvData/), click on the link for the Environmental Studies Program Information System (ESPIS), and 

search on 2020-050. The report is also available at the National Technical Reports Library at 

https://ntrl.ntis.gov/NTRL/.

CITATION

Robertson, T., Campbell, L.K. 2020. Oil spill occurrence rates from Alaska North Slope oil and gas 

exploration, development, and production. Anchorage (AK): US Department of the Interior, Bureau of 

Ocean Energy Management. OCS Study BOEM 2020-050. 72 p.

ABOUT THE COVER

Stored drilling rigs on the Alaska North Slope, photo by Tim Robertson.

ACKNOWLEDGMENTS

This project was funded by the Bureau of Ocean and Energy Management (BOEM) contract 

#140M0119F0003 Alaska Oil Spill Occurrence Estimators Study.

We thank Dr. Heather Crowley and Caryn Smith on the BOEM staff for their review and guidance.
ii

EXECUTIVE SUMMARY

Under contract to the Bureau of Ocean Energy Management (BOEM), Nuka Research and Planning 

Group, LLC developed statistical methods to estimate oil spill occurrence based on past spills in the 

Alaska North Slope region. This information was sought for use in future assessment of potential oil and 

gas production in the Outer Continental Shelf managed by BOEM, though the current oil and gas 

production infrastructure is all based onshore or in state waters.

A dataset of 1,761 spills was compiled from a range of sources of available records covering calendar 

years 1971 through 2019. Spills were included in the dataset if they were larger than 1 barrel and could be 

associated with Alaska North Slope oil and gas exploration, development, or production infrastructure or 

activities. While this included oil field support, it did not include the Trans-Alaska Pipeline System from 

Pump Station #1 downstream.

The full dataset was characterized across oil fields and infrastructure types, as well as presenting the 

number and volume of spills over time:

• The oil fields with highest numbers of spills are the legacy fields that have been operating the 

longest: Prudhoe Bay (980), Kuparuk River (345) and Milne Point (86) account for 80% of the 

number and 86% of the volume of oil spills recorded. 

• The largest number of spills were refined oil (1,042), but these spills only accounted for 38% of 

the total volume. The crude oil category accounted for 719 spills but 62% of total volume (21,123

barrels [bbl]). Much of the difference between crude oil and refined oil volume can be traced to 

the two Class A (>1,000 bbl) oil spills (1,071 in 1971 and 5,054 bbl in 2006).

• The largest number (868) and largest volume (17,964 bbl) of recorded spills were attributed to 

mechanical failure. Spills caused by human error (588) represented about 33% of the number of 

spills and about 31% of the volume (10,496).

• The largest number (1,429) and 78% of the volume (26,645 bbl) of recorded spills were attributed 

to oil production facilities. The support facilities/services category accounted for the next highest 

number (121) and 9% of volume (3,164 bbl). 

• Most spills (1,465) were between 1-10 bbl, totaling a volume of 4,739 bbl. Only 2 spills exceeded 

1,000 bbl each, but these totaled 6,125 by comparison. There were 294 spills between 10-1,000 

bbl, totaling a volume of 23,289 bbl.

While the full dataset was characterized, only spills from 1996-2019 were used to evaluate trends and 

develop the occurrence rate estimators. Familiarity with historic oil spill reporting and prevention 

practices indicated both that industry practices have changed with time (and regulation) and the current 

and best available data tracking system for the area was initiated in mid-1995. 

When comparing spills from 1996-2019 to oil production volumes, the number of spills correlates well 

with production. Both generally decline through 2019. However, annual spill volume does not correlate 

with production well at all. Additionally, when broken down by oil type, it is actually the number of crude 

oil spills that correlates best with production. We observed that the number of crude oil spills declined 

rapidly about 2010 and remained low (below 10) through the remainder of the study period, while the 

number of refined oil spills stayed mostly above 10 spills per year.

Several approaches were tested to develop occurrence estimators. The dependent variables were the total 

volume of oil spilled each year and the total number of spills each year. The following independent 
iii

variables were considered: annual volume of gas produced from gas wells, annual volume of crude oil 

produced from oil wells, annual volume of water produced from oil wells, and average inflation-adjusted 

price of Alaskan crude each year. Overall, the linear correlations were significantly stronger between the 

potential independent variables and the number of spills observed than between the volume of oil spilled. 

This reinforced the decision to focus the regression work on explaining the number of spills, not the 

volume spilled.

A suitable regression model was identified for the annual number of spills using oil production and 

adjusted price as independent variables.

The resulting linear regression model was: 

N_tot = -11.66664 + Oil_Prod. x 0.12482 + Adj_Price x 0.18513

Where: N_tot = total annual number of spills for all spill types and classes

Oil_ Prod. = annual volume of crude oil produced1 from oil wells in million bbl

Adj_Price = Alaska North Slope crude oil price in US adjusted by Consumer 

Price Index to 2019.

The model indicated that for every increase of one million barrels (MMbbl) of oil production, the number 

of annual spills is expected to increase 0.12 units for all spill types and classes. This model explains 53% 

of the variation observed in the annual number of spills. The model’s calculated multivariate power was 

0.9983. The power is exceptionally good. 

By contrast, it was not possible to develop a regression model to estimate the annual volume of oil spills. 

Instead, a bootstrapping procedure and Monte Carlo simulation was used to estimate the spill volume. 

The resulting formula to estimate the total annual spilled volume was:

Vol_toty = Pred_N_toty x Prop_A x Med_A + Pred_N_toty x Prop_B x Med_B + Pred_N_toty x 

Prop_C x Med_C + Pred_N_toty x Prop_D x Med_D

Where: Pred_N_toty = total number of spills predicted for oil production Y using the 

regression model with multiple realizations created via a Monte Carol simulation.

Prop_X = Proportion of spills from Class X estimated using the bootstrapped 

procedure

Med_X = Median spill size of Class X estimated using the bootstrapped 

procedure

Occurrence estimates were also sought for crude and refined spills separately. The occurrence model to 

predict annual number of crude oil spills is very similar to the model developed to predict annual number 

of all types of oil. Applying the above modeling approach to the Alaska North Slope annual crude oil spill 

data resulted in a regression model with Oil Production as the single independent variable.

 

1 Crude oil production values do not include natural gas liquids.
iv

The resulting linear regression model was: 

N_crude_tot = -5.251565 + Oil Prod. x 0.065857

Where: N_crude_tot = total annual number of crude oil spills

Oil_ Prod. = annual volume of crude oil produced from oil wells in million bbl

The model indicates that for every increase of 1 MMbbl of oil production the number of annual crude oil 

spills is expected to increase 0.066 units. The model explains 67% of the variation observed in the annual 

number of spills. 

The model used for crude spills was not useful for predicting annual numbers of refined spills, however. 

There was no significant relationship between annual number of refined oil spills and any of the 

independent variables investigated. The best estimator of the annual number of refined oil spills is the 

mean value, which is equal to 20.9 refined spills per year. 

The limitations of the models developed should be noted. These include the small size of the dataset (24 

years) and changes in reporting over time. Occurrence estimates might also be improved by using more 

independent variables, though in order to be useful these need to be variables that can be estimated or 

planned on for the future.
v

Contents

1 INTRODUCTION .............................................................................................................................1

1.1 Purpose ..................................................................................................................................1

1.2 Project Scope .........................................................................................................................1

1.2.1 Alaska North Slope Oil and Gas Operations........................................................................1

2 METHODS AND ASSUMPTIONS....................................................................................................3

2.1 Oil Spill Data Collection and Collation......................................................................................3

2.1.1 Spill Size Classes ...............................................................................................................4

2.1.2 Spill Substance...................................................................................................................5

2.1.3 Activity/Facility ....................................................................................................................5

2.1.4 Spill Source ........................................................................................................................6

2.1.5 Spill Cause .........................................................................................................................6

2.1.6 Spill Records and Years Included in Final Dataset ..............................................................7

2.2 Exposure Variable Data ..........................................................................................................7

3 SUMMARY OF HISTORICAL SPILL OCCURRENCE DATA............................................................7

3.1 Total Spills Over Time.............................................................................................................7

3.2 Overview of Recorded Spills ...................................................................................................7

3.2.1 Spill Occurrence by Oil Field or Infrastructure Component...................................................9

3.2.2 Overall Spill Occurrence by Cause....................................................................................10

3.2.3 Spill Occurrence by Activity/Facility Type ..........................................................................11

3.2.4 Spill Occurrence by Substance Type.................................................................................11

3.2.5 Summary Spill Data by Size Class ....................................................................................12

4 TREND ANALYSIS........................................................................................................................15

4.1 Choosing a Timeframe for Trend and Occurrence Analysis ...................................................15

4.2 Annual Data vs. Monthly Data...............................................................................................17

4.3 Seasonality in Alaska North Slope Spill Rates .......................................................................17

4.4 Spill Trends by Year..............................................................................................................18

4.5 Spill Trends by Product Type ................................................................................................20

5 SPILL RATE OCCURRENCE ESTIMATES....................................................................................21

5.1 Annual Number of Spills Over Time.......................................................................................21

5.1.1 Screening Independent Variables......................................................................................21

5.1.2 Modeling Approach...........................................................................................................23

5.2 Predicting Annual Spill Numbers from Crude Oil Production Using Linear Regression ...........23
vi

5.3 Predicting Annual Spill Volume from Crude Oil Production ....................................................27

5.4 Estimating Occurrence Rates by Oil Type .............................................................................32

5.4.1 Occurrence Rates for Number of Spills by Oil Type...........................................................32

5.4.2 Occurrence Rates for Annual Volume of Spills by Oil Type................................................35

6 CONCLUSIONS ............................................................................................................................35

6.1 Limitations and Challenges of Occurrence Models ................................................................35

6.2 Occurrence Estimates for Spill Number.................................................................................36

6.3 Occurrence Estimates for Spill Volume..................................................................................36

6.4 Recommendations ................................................................................................................37

7 REFERENCES ..............................................................................................................................37

8 APPENDICES................................................................................................................................39

Appendix A: Collated Oil Spill Dataset.................................................................................................. A-1

Appendix B: Exposure Variable Datasets............................................................................................. B-1
vii

List of Figures

Figure 1. Alaska North Slope oil fields and associated infrastructure ........................................................2

Figure 2. Overview of Alaska North Slope spills by cause, activity, substance, and oil field, 1971-2019 ....8

Figure 3. Overview of Alaska North Slope spills by size class, cause, activity/facility, substance, and oil 

field, 1971-2019.....................................................................................................................................13

Figure 4. Number of recorded oil spills by size class in the Alaska North Slope region, 1971–2019 ........16

Figure 5. Comparison of the frequency distribution for spills per month vs. spills per year for Alaska North 

Slope spills, 1996–2019.........................................................................................................................17

Figure 6. Total number of recorded oil spills by month in the Alaska North Slope region, 1988–2019 and 

1996–2019 ............................................................................................................................................18

Figure 7. Annual number of recorded oil spills plotted against the annual oil production for the Alaska 

North Slope region, 1996–2019 .............................................................................................................19

Figure 8. Annual recorded volume of oil spills plotted against the annual oil production for the Alaska 

North Slope region, 1996–2019 .............................................................................................................19

Figure 9. Annual recorded number of oil spills for crude oil and refined oil plotted against the annual oil 

production for the Alaska North Slope region, 1996–2019 ......................................................................20

Figure 10. Annual recorded volume of oil spills for crude oil and refined oil plotted against the annual oil 

production for the Alaska North Slope region, 1996–2019 ......................................................................21

Figure 11. Scatterplot matrix, distribution, and the Pearson Correlation Coefficient for each variable 

considered for inclusion in the modeling process....................................................................................22

Figure 12. Predicted value, 95% confidence interval, and 95% prediction interval for the expected number 

of all oil spills for the range of oil production values studied with adjusted price of $75 per barrel for the 

Alaska North Slope region .....................................................................................................................25

Figure 13. Predicted number of all oil spills for the range of oil production values studied at five different 

adjusted oil prices..................................................................................................................................26

Figure 14. Distribution of volume of recorded oil spill in the Alaska North Slope region, 1996–2019........27

Figure 15. Bootstrap estimate of the distribution of proportions for each spill class for Alaska North Slope 

Spills 1996–2019. ..................................................................................................................................30

Figure 16. Bootstrap/Monte Carlo estimate of the predicted annual volume of oil spilled vs crude oil 

production for the Alaska North Slope region .........................................................................................32

Figure 17. Predicted value, 95% confidence interval, and 95% prediction interval for the expected number 

of North Slope crude oil spills for the range of oil production values studied ...........................................34
viii

List of Tables

Table 1. Variables for each spill record ....................................................................................................4

Table 2. Year of first production from Alaska North Slope productions units .............................................9

Table 3. Alaska North Slope spills by oil field and infrastructure, 1971–2019 ............................................9

Table 4. Largest recorded spill at each oil field and percent of total volume of spills from that field 

represented by the largest spill, 1971-2019............................................................................................10

Table 5. Alaska North Slope spill occurrence and percent of total spill volume by cause, 1971-2019 ......10

Table 6. Alaska North Slope spill occurrence and percent of total spill volume by activity/facility type, 

1971-2019 .............................................................................................................................................11

Table 7. Alaska North Slope spill occurrence and percent of total spill volume by substance, 1971–2019

..............................................................................................................................................................12

Table 8. Alaska North Slope spill occurrence and percent of total spill volume by size class, 1971–201914

Table 9. Two Class A and 26 Class B spills recorded in the Alaska North Slope, 1971–2019 .................14

Table 10. Pearson Correlation Coefficient and p-value for independent variables related to annual number 

and volume of spills recorded in Alaska North Slope, 1996–2019...........................................................23

Table 11. Statistics for the linear regression model predicting annual spills number from oil production and 

adjusted price ........................................................................................................................................24

Table 12. Pearson Correlation Coefficient and p-value for independent variables related to annual volume 

of spills recorded in the Alaska North Slope region, 1996–2019 .............................................................28

Table 13. Expected annual number of spills and corresponding 95% confidence interval for four levels of 

oil production for the Alaska North Slope region with the adjusted crude oil price fixed at $75 per bbl.....30

Table 14. Median spill size by class and corresponding 95% confidence interval for Alaska North Slope 

recorded spills 1996–2019 with the adjusted crude oil price fixed at $75 per bbl.....................................31

Table 15. Expected annual number of spills and corresponding 95% confidence interval four size classes 

and four levels of oil production with the adjusted crude oil price fixed at $75 per bbl; and estimated total 

annual volume of spills for the Alaska North Slope region predicted from the bootstrap method and Monte 

Carlo simulation.....................................................................................................................................31

Table 16. Statistics for the linear regression model predicting annual spills number of crude oil spills from 

oil production .........................................................................................................................................33

Table 17. Median annual spill volume and 95% Percentile Interval by oil type for North Slope oil spills, 

1996–2019 ............................................................................................................................................35

Table B-1. Adjusted Alaska North Slope crude oil pricing, 1996–2019......................................................1

Table B-2. North Slope gas production per year, 1949–2019....................................................................2

Table B-3. North Slope oil production per year, 1969–2019......................................................................3
ix

List of Abbreviations and Acronyms

ADEC Alaska Department of Environmental Conservation

AIC statistic Akaike Information Criteria

bbl barrel

BOEM Bureau of Ocean Energy Management

DOI US Department of the Interior

mcf million cubic feet 

MMbbl Million barrels

NGL Natural Gas Liquids

NRC National Response Center

OCS Outer Continental Shelf

RMSE root mean square error

VIF statistic Variable Inflation Factor
1

1 INTRODUCTION

Nuka Research and Planning Group, LLC completed this study under Contract #140M0119F0003 to the 

Bureau of Ocean Energy Management (BOEM) Alaska Regional Office.

1.1 Purpose

The purpose of project was to develop oil spill occurrence estimators for the Alaska North Slope based on 

available data on past onshore and offshore spills in the region. 

The objectives of this analysis were to: 

• Develop a dataset of crude and refined oil spill records for Alaska North Slope;

• Develop a dataset of crude oil and gas production, and other possible independent variables for 

developing an oil spill occurrence rate model for Alaska's North Slope;

• Provide statistical measures of crude and refined oil spills such as mean and median spill sizes 

with confidence intervals as appropriate;

• Use statistical analysis to identify trends in spill rates and volumes;

• Categorize Alaska North Slope spills into size classes;

• Apply statistical procedures to develop occurrence rate estimator models for crude and refined oil 

spills, as well as all spills; and

• Develop an appropriate confidence interval for occurrence rate estimators.

This report updates a similar study completed in 2013 (Robertson et al., 2013). Other previous work on 

OCS historical platform and pipeline crude oil spill occurrence rates relies on data from the Gulf of 

Mexico and Pacific OCS (ABS Consulting Inc. 2016; ABSG Consulting Inc. 2018; Anderson and 

LaBelle, 2000; Anderson, Mayes & LaBelle, 2012; Eschenbach et al., 2010). 

1.2 Project Scope

For the purpose of the study, the project scope was defined by whether the spill was associated with oil 

and gas exploration, development, or production activities and the geographic area (encompassing the 

boundaries of the North Slope Borough, including adjacent shorelines and marine waters out to the 

Exclusive Economic Zone).

1.2.1 Alaska North Slope Oil and Gas Operations

This analysis considers past spills associated with oil exploration, development, production, storage and

transportation infrastructure on Alaska’s North Slope, including construction and maintenance activities. 

Oil produced in the region is moved by pipeline to the Trans-Alaska Pipeline's Pump Station 1. Figure 1 

shows the location of the North Slope oil fields and associated piping, drill sites, pipelines, pump stations, 

and processing centers. This study focused on spills associated with oil and gas exploration, development, 
2

and production activities. The study does not include spills associated with the Trans-Alaska Pipeline 

from Pump Station 1 and south, nor spills of solely produced water2 or other hazardous substances.

Figure 1. Alaska North Slope oil fields and associated infrastructure

 

2 Spills of a mixture of produced water and crude oil were included, but only the volume of crude oil was analyzed.
3

2 METHODS AND ASSUMPTIONS

This section describes the methods, inputs, and assumptions applied to the analysis.

2.1 Oil Spill Data Collection and Collation

Nuka Research collated data from various sources including:

• Alaska Department of Environmental Conservation oil spill database3

• Reports of oil spills to federal agencies through the National Response Center (NRC)4

• Pipeline and Hazardous Materials Safety Administration database report from September 11, 

2018, provided by BOEM.

• Robertson, et al 2013 (previous Alaska North Slope oil spill occurrence rates study)

Each spill record was reviewed. Spills of larger than 1 bbl were included in the data if they were deemed 

to originate from infrastructure or activities within the project scope. Spills were then categorized based 

on the information available and the best professional judgement of the Principle Investigator. Ten 

percent of records were randomly selected and verified back to the original source.

The original oil spill datasets each had different data structures. The collation process involved 

transforming each dataset into a common format that would facilitate the merging of records from a single 

spill. In all cases, spill volumes were converted to barrels. In some datasets, multiple variables from a 

single record were concatenated into a single variable. Table 1 presents the data scheme for the final 

dataset with notes about how these variables relate to the original datasets. The final dataset (Appendix A) 

consists of 1,761 records with each representing a single spill event covering calendar years 1971 through 

2019.

 

3 https://dec.alaska.gov/Applications/SPAR/PublicMVC/PERP/SpillSearch

4 https://nrc.uscg.mil/
4

Table 1. Variables for each spill record

Variable Information

Spill ID Unique identifier for this dataset. 

Primary Source The primary source record for the spill. 

Source ID The identifier from the primary source.

Additional Sources Other sources where a record of the spill was found.

Spill Date The date that the spill occurred, if it was known.

Spill Year The calendar year that the spill occurred.

Spill Size (bbl) The best or maximum estimate of the spill size in barrels5

(42 US gallons).

Spill Size Class Spill size category. See Section 2.1.1.

Substance The category of the oil substance spilled. See Section 2.1.2

Consolidated 

Substance

A consolidation of oil substances. See Section 2.1.2.

Facility/Activity Type The category of facility type. See Section 2.1.3.

Consolidated 

Facility/Activity Type

A consolidation of facility types. See Section 2.1.3.

Location The category of the location of the spill, either Offshore, Onshore, or 

Unknown.

Oil Field / Infrastructure The oil field or infrastructure where the spill occurred. See 

Section 3.2.1.

Spill Source The category of the source of the spill. See Section 2.1.4.

Spill Cause The category of the spill cause. See Section 2.1.5.

Consolidated Spill 

Cause

A consolidation of spill causes. See Section 2.1.5.

2.1.1 Spill Size Classes

Only spills larger than one barrel (bbl) were included. The following spill size classes, as defined in 

Robertson 2013, were used for this study:

• A = oil spills > 1,000 bbl

• B = oil spills > 200 bbl and ≤ 1,000 bbl

• C = oil spills > 10 bbl and ≤ 200 bbl

• D = oil spills > 1 bbl and ≤ 10 bbl

• E = oil spills ≤ 1 bbl (excluded from this analysis)

Spills less than or equal to one barrel were not considered because of the historical inconsistency in 

reporting of small spills. 

 

5 Note that spill size values in this report are rounded to the nearest bbl, but data in the analysis were carried to two 

decimal places.
5

2.1.2 Spill Substance

The following consolidated spill substances were used:

• Crude Oil

• Crude Oil and Produced Water

• Refined: Diesel

• Refined: Natural Gas Liquids

• Refined: Other

Consolidated spill substances were developed based on the categories used:

• Crude Oil

• Crude Oil and Produced Water

• Refined: Asphalt

• Refined: Aviation

• Refined: Ballast Water with Oil

• Refined: Bunker Oil

• Refined: Diesel

• Refined: Gasoline

• Refined: Hydraulic Oil

• Refined: Jet Fuel

• Refined: Lube/Gear Oil

• Refined: Naphtha

• Refined: Natural Gas Liquids

• Refined: Turbine Oil

• Refined: Unknown

• Refined: Unknown and Water

Where spills were of a mixed substance type, such as crude oil and produced water, only the oil portion of 

the mixture was included in the final dataset. For spills of produced water and oil where the proportion of 

oil and water was not identified, the proportion was estimated during the analysis using the best available 

information for the specific spill case.

2.1.3 Activity/Facility 

The following consolidated activity/facility types were used:

• Oil Production

• Oil Exploration

• Support Facility/Services

• Unknown

Consolidated activity/facility types were developed based on the categories used:

• Air Transportation (Support Facility/Services)

• Bulk Fuel Terminal (Support Facility/Services)

• Oil Exploration (Oil Exploration)

• Oil Production (Oil Production)

• Support Facility/Services (Support Facility/Services)

• Transmission Pipeline (Oil Production)

• Unknown (Unknown)

• Vehicle (Support Facility/Services)

• Waste Disposal (Support Facility/Services)
6

2.1.4 Spill Source

The following spill source categories were used:

• Coiled Tubing Unit

• Container, Other

• Drilling Activities

• Drum(s)

• Equipment Failure, Vehicle

• Flare

• Fuel Pump

• Heavy Equipment

• Hydraulic System

• J TUBE

• Loading Arm

• Other

• Pipe or Line

• Tank, Aboveground

• Tank, Mobile

• Tank, Other

• Unknown

• Vehicle

• Vessel

• Vessel Transfer

• Well

2.1.5 Spill Cause

The following consolidated spill causes were used:

• Human Error: Other

• Human Error: Overfill

• Human Error: Unknown

• Mechanical Failure: Corrosion

• Mechanical Failure: Other

• Mechanical Failure: Overpressure

• Mechanical Failure: Unknown

• Mechanical Failure: Valve/Seal

• Other

• Unknown

Consolidated spill causes were developed based on the categories used:

• Cargo Not Secured

• Collision/Allision/Grounding

• Containment Overflow

• Corrosion

• Crack

• Dumping

• Equipment Failure, Gauge/Sight Glass 

Failure

• Equipment Failure, Line Failure

• Equipment Failure, Other

• Equipment Failure, Seal Failure

• Equipment Failure, Tank Failure

• Equipment Failure, Unknown

• Equipment Failure, Valve Failure

• Equipment Failure, Vehicle

• Erosion

• External Factors

• Fire/Explosion

• Freezing

• Hull Failure

• Human Error

• Human Error, Overfill

• Miss-Injection

• Other

• Overpressure

• Puncture

• Rollover/Capsize

• Unknown

• Weld Failure
7

2.1.6 Spill Records and Years Included in Final Dataset

The final oil spill dataset from 1971–2019 included 1,761 spills larger than one barrel. As discussed in 

Section 4 however, a shorter time period was used for the development of the occurrence estimator.

2.2 Exposure Variable Data

Exposure or independent variable data considered for this analysis included oil production and adjusted 

oil prices.

Data on crude oil production by month from 1949-2019 was compiled from the Alaska Oil and Gas 

Conservation Commission’s records and combined into a workbook with a separate spreadsheet for each

of the 10 distinct producing oil fields on the Alaska North Slope. Data for each month includes barrels of 

oil produced, barrels of water produced, million cubic feet of gas produced, and number of producing 

wells. Note that crude oil values do not include natural gas liquids.

Adjusted Oil Price data for Alaska North Slope crude oil were taken from US Energy Information 

Administration (EIA, 2020) and adjusted by the Consumer Price Index to 2019 US dollars. 

These data, which are included in Appendix B, were used as independent variables for developing 

occurrence estimators.

We would like to have also used pipeline mileage as an independent variable, as it provided useful for 

estimating oil spill numbers in a prior study (Robertson, et. al., 2013), but current pipeline mileage by 

year data are not available for North Slope from operators or regulators. Nuka Research did an inventory 

of flow lines and oil transmission pipelines in 2010 for another project and it has not been updated since. 

An accurate inventory of pipeline miles with year placed in service might improve the oil spill occurrence 

rate estimator as was seen in the 2013 report (Robertson, et. al., 2013). 

3 SUMMARY OF HISTORICAL SPILL OCCURRENCE DATA 

This section summarizes the spill data from 1971-2019 by the number of spills, spill volume, oil field, 

and cause, examining each of these factors as related to the spill size categories.

3.1 Total Spills Over Time

There were 1,761 spills greater than one barrel recorded with a total volume of 34,153 barrels of oil 

spilled in the final dataset for Alaska North Slope. The earliest spill in the dataset occurred on June 3, 

1971 and the last spill occurred on November 10, 2019. 

3.2 Overview of Recorded Spills

Figure 2 shows the number and volume of recorded spills for each cause, activity, substance, and oil 

field/infrastructure. Each of these factors will be discussed independently in sections below.
8

Figure 2. Overview of Alaska North Slope spills by cause, activity, substance, and oil field, 1971-

2019 
9

3.2.1 Spill Occurrence by Oil Field or Infrastructure Component

Oil was first produced on the Alaska North Slope in 1969 as shown in Table 2. This section presents spill 

occurrence by oil field or infrastructure component, as shown in Table 3. The oil fields with highest 

numbers of spills are the legacy fields that have been operating the longest: Prudhoe Bay (980), Kuparuk 

River (345) and Milne Point (86) account for 80% of the number and 86% of the volume of oil spills

recorded. 

Table 2. Year of first production from Alaska North Slope productions units

Production Unit Year of First 

Production

Prudhoe Bay 1969

Kuparuk River 1970

Milne Point 1985

Endicott 1986

Badami 1998

Colville River, Alpine 2000

North Star 2001

Oooguruk 2003

Nikaitchuq 2011

Point Thompson 2016

Table 3. Alaska North Slope spills by oil field and infrastructure, 1971–2019

Oil Field -

Infrastructure

Number Percent 

Number

Total Volume 

(bbl)

Percent Total 

Volume

Prudhoe Bay 980 56% 22,330 65%

Kuparuk River 345 20% 5,019 15%

Unknown 157 9% 3,179 9%

Milne Point 86 5% 1,988 6%

Endicott 37 2% 482 1%

Support Services 45 3% 360 1%

Colville River, Alpine 29 2% 221 1%

Badami 15 1% 179 1%

Oooguruk 11 1% 125 <1%

Exploration 17 1% 101 <1%

North Star 15 1% 94 <1%

Nikaitchuq 14 1% 39 <1%

Point Thompson 10 1% 36 <1%

Grand Total 1761 100% 34,153 100%

Table 4 shows the percentage of the total volume accounted for by the largest oil spill in each oil 

field/infrastructure category. Excluding unknowns, the largest oil spill accounted for more than 50% of 

the total volume spilled in three of the 12 categories. The reader should keep in mind that spills of less 

than or equal to one barrel are not included and that larger spills are probably more likely to be reported 

than smaller spills. Also, these spills do not include spills on the Alaska North Slope from the 

construction of the Trans-Alaska Pipeline System.
10

Table 4. Largest recorded spill at each oil field and percent of total volume of spills from that field 

represented by the largest spill, 1971-2019

Oil Field -

Infrastructure

Maximum Spill 

(bbl)

% Total 

Volume

Oooguruk 100 80%

Badami 109 61%

Endicott 287 59%

North Star 46 49%

Milne Point 925 47%

Support Services 124 34%

Colville River, Alpine 71 32%

Unknown 952 30%

Nikaitchuq 9 24%

Exploration 24 23%

Prudhoe Bay 5054 23%

Point Thompson 7 19%

Kuparuk River 675 13%

3.2.2 Overall Spill Occurrence by Cause

Table 5 shows the number and volume of oil spills by cause. The largest number (868) and largest volume 

(17,964 bbl) of recorded spills were attributed to mechanical failure. Spills caused by human error (588) 

represented about 33% of the number of spills and about 31% of the volume (10,496). The cause was 

unknown for 284 spills, representing 5,306 bbl.

Table 5. Alaska North Slope spill occurrence and percent of total spill volume by cause, 1971-2019

Consolidated Cause Number Percent 

Number

Total Volume

(bbl)

Percent 

Total 

Volume

Mechanical Failure 868 49% 17,964 53%

Mechanical Failure: Corrosion 29 2% 5,811 17%

Mechanical Failure: Other 433 25% 8,410 25%

Mechanical Failure: Overpressure 15 1% 663 2%

Mechanical Failure: Unknown 161 9% 1,119 3%

Mechanical Failure: Valve/Seal 230 13% 1,961 6%

Human Error 588 33% 10,496 31%

Human Error: Other 29 2% 378 1%

Human Error: Overfill 186 11% 2,264 7%

Human Error: Unknown 373 21% 7,854 23%

Unknown 284 16% 5,305 16%

Other 21 1% 389 1%

Grand Total 1,761 100% 34,153 100%
11

3.2.3 Spill Occurrence by Activity/Facility Type

Table 6 shows the number and volume of oil spills by activity/facility type. The largest number (1,429) 

and 81% of the volume (26,645 bbl) of recorded spills were attributed to oil production facilities. The 

support facilities/services category accounted for the next highest number (121) and 9% of volume (3,164

bbl). All other facility categories total of 211 spills and 13% of the volume (4,344 bbl). It is likely that 

there is overlap and inconsistency in reporting of facility type in these data. For instance, spills from 

vehicles may be recorded under support facilities/services.

Table 6. Alaska North Slope spill occurrence and percent of total spill volume by activity/facility 

type, 1971-2019

Activity/Facility Type Number Percent 

Number

Total Volume

(bbl)

Percent 

Total 

Volume

Oil Production 1,429 81% 26,645 78%

Support Facility/Services 121 7% 3,164 9%

Vehicle 69 4% 1,639 5%

Oil Exploration 23 1% 1,284 4%

Unknown 95 5% 1,036 3%

Bulk Fuel Terminal 14 1% 333 1%

Air Transportation 6 <1% 28 <1%

Transmission Pipeline 2 <1% 21 <1%

Waste Disposal 2 <1% 3 <1%

Grand Total 1,761 100% 34,153 100%

3.2.4 Spill Occurrence by Substance Type

Table 7 shows the number and volume of oil spills by substance. The largest number of spills were 

refined oil (1,042), but these spills only accounted for 38% of the total volume. The crude oil category 

accounted for 719 spills but 62% of total volume (21,123 bbl). Much of the difference between crude oil 

and refined oil volume can be traced to the two Class A oil spills (1,071 in 1971 and 5,054 bbl in 2006). 

In general, the potential spill size will be bigger for crude oil than for refined oil because the quantity of 

crude oil handled is vastly larger than the quantity of refined oil. However, refined oil is handled in many 

more processes and is therefore more likely to be spilled.
12

Table 7. Alaska North Slope spill occurrence and percent of total spill volume by substance, 

1971–2019

Substance Number Percent 

Number

Total 

Volume

(bbl)

Percent 

Total 

Volume

Crude Oil 719 41% 21,123 62%

Refined 1,042 59% 13,030 38%

Refined: Diesel 680 39% 9,397 28%

Refined: Other 356 20% 3,616 11%

Refined: Natural Gas Liquids 6 0.3% 18 0.1%

Grand Total 1,761 100% 34,153 100%

3.2.5 Summary Spill Data by Size Class

Figure 3 presents the volume of recorded oil spills by size class for cause, activity/facility type, substance, 

and oil field/infrastructure.
13

Figure 3. Overview of Alaska North Slope spills by size class, cause, activity/facility, substance, 

and oil field, 1971–2019

Table 8 shows the number and volume of recorded oil spills by size class. The Class A contains the 

lowest number (2) and the third largest volume (6,125). Thus, the smallest spill size category contains 

83% of the number of spills (1,475), but represents only 14% of the total volume spilled (4,739 bbl).

Classes B and C account for about the same volume spilled, but there were 10 times more class C spills

compared to Class B.
14

Table 8. Alaska North Slope spill occurrence and percent of total spill volume by size class, 1971–

2019

Size Class Number Percent Total Volume

(bbl)

Percent Total 

Volume

A > 1,000 bbl 2 <1% 6,125 18%

B > 200 bbl & ≤ 1,000 bbl 25 1% 11,202 33%

C > 10 bbl & ≤ 200 bbl 269 15% 12,087 35%

D 1 bbl & ≤ 10 bbl 1,465 83% 4,739 14%

Grand Total 1,761 100% 34,153 100%

Table 9 presents the two Class A (> 1,000 bbl) and 26 Class B (>200 and ≤1,000 bbl) oil spills recorded 

in the Alaska North Slope. The largest spill of 5,054 bbl (March 2006) was from a mechanical failure due 

to corrosion of a pipeline in the Prudhoe Bay oil field which was then operated by BP Exploration, 

Alaska. The second largest spill of 1,071 bbl (June 1971) was from human error, but the source and 

location are unknown. 

Table 9. Two Class A and 26 Class B spills recorded in the Alaska North Slope, 1971–2019

Date Spill 

Volume

(bbl)

Oil field Substance Source Cause

Class A Spills

6/3/71 1071 Prudhoe Bay Refined Unknown Human Error: Unknown

3/2/06 5054 Prudhoe Bay Crude Pipe or Line Mechanical Failure: Corrosion

Class B Spills

1/5/72 476 Prudhoe Bay Refined Unknown Human Error: Overfill

7/16/73 952 Unknown Refined Unknown Unknown

8/22/81 450 Prudhoe Bay Refined Unknown Mechanical Failure: Other

6/2/85 238 Prudhoe Bay Crude Unknown Mechanical Failure: Unknow

11/14/85 250 Prudhoe Bay Refined Unknown Human Error: Unknown

1/5/87 357 Prudhoe Bay Refined Unknown Human Error: Unknown

2/8/88 287 Endicott Crude Unknown Unknown

3/30/88 281 Prudhoe Bay Crude Pipe or Line Human Error: Unknown

4/18/89 357 Unknown Refined Unknown Unknown

7/28/89 925 Milne Point Crude Unknown Mechanical Failure: Other

8/25/89 600 Kuparuk River Crude Pipe or Line Human Error: Unknown

11/8/89 265 Kuparuk River Crude Unknown Mechanical Failure: Other

12/10/90 600 Prudhoe Bay Crude Unknown Unknown

6/10/93 300 Prudhoe Bay Crude Unknown Mechanical Failure: Other

8/17/93 675 Kuparuk River Crude Unknown Human Error: Unknown

9/26/93 650 Prudhoe Bay Crude Unknown Mechanical Failure: Other
15

Date Spill 

Volume

(bbl)

Oil field Substance Source Cause

12/30/93 400 Prudhoe Bay Crude Unknown Human Error: Unknown

1/10/98 300 Kuparuk River Crude Unknown Unknown

4/7/99 260 Prudhoe Bay Refined Unknown Human Error: Unknown

8/21/00 715 Prudhoe Bay Crude Unknown Mechanical Failure: Other

2/19/01 607 Prudhoe Bay Crude Pipe or Line Mechanical Failure: 

Overpressure

11/17/03 262 Prudhoe Bay Refined Tank Human Error: Unknown

10/31/06 220 Prudhoe Bay Refined Unknown Human Error: Unknown

12/25/08 452 Kuparuk River Crude Pipe or Line Mechanical Failure: Other

11/29/09 321 Prudhoe Bay Crude Pipe or Line Mechanical Failure: Other

4 TREND ANALYSIS

4.1 Choosing a Timeframe for Trend and Occurrence Analysis

Review of the 1971–2019 dataset compiled for this project (and summarized in Section 3) indicated that 

data prior to 1996 appeared less reliable than 1996–2019. While the first oil production data for the 

Alaska North Slope occurred in April 1969, the first recorded spill in the dataset did not occur until more 

than 2 years later (June 1971). The June 1971 spill was a large one (Class A of 1,071 bbl.) The first small 

spill (Class D) was recorded in 1972. Records for fewer than 20 spills per year were identified before

1978 when the Alaska Pipeline became operational and the oil production was ramping up. See Figure 4.
16

Figure 4. Number of recorded oil spills by size class in the Alaska North Slope region, 1971–2019 

Two timeframes were considered for a trend analysis: 1988–2019 and 1996–2019. The 1988–2019

timeframe was initially considered desirable because it would offer a larger sample size (31 years) and 

thus more statistical power to the model. However, data from 1996 onward had adequate sample size (23 

years) and was collected after improvements to the State of Alaska reporting system had been established

in 1995. A final decision on which timeframe to use for the trend analysis was made based on comparing

models constructed using both timeframes. Each model's ability to predict the last decade’s (2009–2019) 

spill numbers was then compared. A statistic called the root mean square error (RMSE) was used. RMSE 

is computed by averaging the squared deviations (predicted value - observed value) and then taking the 

square root of that figure. When comparing models, the one with the lowest RMSE is generally better. It 

was found that:

• The RMSE using a model built from 1988–2019 data was 7.80

• The RMSE using a model built from 1996–2019 data was 7.84

This difference between the two models is very small and indicates that using a model built from the more 

recent dataset (1996–2019) will not be inferior to the longer dataset of 1988–2019. Thus, it was decided 

that data from 1996–2019 (23 years) would be used for trend analysis and occurrence rate estimates. This 

decision was also supported by the following aspects of the operational context:

• Inconsistency in spill databases before 1995 (the current State of Alaska database was begun 

mid-year that year)

• Inconsistency in spill reporting and reporting requirements in early years

• Industry spill prevention practices improved after 1990 and thus spills since that time reflect 

current practices.

0

20

40

60

80

100

120

1971197319751977197919811983198519871989199119931995199719992001200320052007200920112013201520172019

Number of Spills

Year

Number of Spill by Size Class by Year

Class A > 1,000 bbl

Class B > 200 to ≤ 1,000 bbl

Class C > 100 to ≤ 200 bbl

Class D > 1 to ≤ 10 bbl
17

4.2 Annual Data vs. Monthly Data

It was also necessary to decide whether to focus on a model built using monthly data or annual data. 

Monthly data would have provided a much greater sample size and consequently more power if a valid 

model could be achieved. However, data on the number of spills per month has some features that make it 

unsuitable for modeling. First, the distribution is highly non-normal. Second, even those months with 

spills generally have a very small number of spills for statistical purposes. So, the interval variable ‘spills 

per month’ does not approximate a continuous variable suitable for modeling. For annual data there were 

no years with fewer than 12 spills and the range was from 12 to 54 for 1996–2019. In short, the 

distribution using annual data was more normal, which is a prerequisite for linear regression modeling.

Figure 5 compares the distributions of Alaska North Slope monthly spills vs. annual spills 1996–2019.

Figure 5. Comparison of the frequency distribution for spills per month vs. spills per year for

Alaska North Slope spills, 1996–2019

4.3 Seasonality in Alaska North Slope Spill Rates

We examined both 1988–2019 and 1996–2019 spill data to determine whether or not there is a seasonal

pattern inherent in Alaska North Slope spills (Figure 6). In both timeframes, more spills were recorded in 

June than any other month and the fewest spills were recorded in October. One possible explanation of 

more spills in June is that more maintenance and construction activities may occur during long daylight 

and mild temperatures. Previous spills might also be revealed under melting snow and ice. The smaller 

number of spills recorded in the fall may be due to there being less activity in advance of freeze-up and 

reduced daylight. We used the Kruskal-Wallis test to determine if this variation by month in the median 

number of recorded spills was statistically significant and found that it was for 1988–2019 but not for 

1996–2019.

6

 The same seasonal pattern is evident in both time frames but was not as pronounced or 

 

6 Kruskal-Wallis: 1998–2019 chi-squared = 19.51, df = 11, p-value = 0.05

1996–2019 chi-squared = 15.08, df = 11, p-value = 0.18

0

10

20

30

40

50

60

70

0 1 2 3 4 5 6 7 8 9 10 11

Number of Months

Spills per Month

Frequency of Spills per Month

1996 - 2019

0

1

2

3

4

5

6

0 5 10 15 20 25 30 35 40 45 50 55 60

Number of Years

Spills per Year

Frequency of Spills per Year

1996 - 2019
18

statistically significant in the 1996–2019. The seasonality of Alaska North Slope spills appears to have 

weakened over time.

Figure 6. Total number of recorded oil spills by month in the Alaska North Slope region, 1988–

2019 and 1996–2019

4.4 Spill Trends by Year

Figure 7 shows the annual recorded number of spills plotted against the annual oil production for the 

Alaska North Slope region from 1996 through 2019. The graph suggests that for this time range the 

number of spills roughly follows the production curve when annual values for each are plotted 

simultaneously. Clearly as production dropped over time, so did the total number of spills recorded.

0

20

40

60

80

100

120

140

160

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Number of Spills

Number of Spills by Month 1988 - 2019

0

10

20

30

40

50

60

70

80

90

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Number of Spills

Number of Spills by Month 1996 - 2019
19

Figure 7. Annual number of recorded oil spills plotted against the annual oil production for the 

Alaska North Slope region, 1996–2019

Figure 8 shows the annual volume of recorded oil spills compared to annual oil production for the Alaska 

North Slope region from 1996–2019. The large spill in 2006 is a clear anomaly. In contrast to the number 

of spills, the spill volume, however, does not closely follow the production profile. This indicated that 

predicting the number of spills will be easier than predicting the volume spilled.

Figure 8. Annual recorded volume of oil spills plotted against the annual oil production for the 

Alaska North Slope region, 1996–2019

 -

 100

 200

 300

 400

 500

 600

0

10

20

30

40

50

60

199619971998199920002001200220032004200520062007200820092010201120122013201420152016201720182019

Oil Production (million bbl)

Number of Spills

Number of Spills vs. Oil Production by Year

Spills

Production

 -

 100

 200

 300

 400

 500

 600

 -

 1,000

 2,000

 3,000

 4,000

 5,000

 6,000

 7,000

199619971998199920002001200220032004200520062007200820092010201120122013201420152016201720182019

Oil Production (million bbl)

Volume of Spills (bbl)

Volume of Spills vs. Oil Production by Year

Spills

Production
20

4.5 Spill Trends by Product Type

Figure 9 shows the yearly annual recorded number of crude and refined oil spills plotted against the 

annual oil production for the Alaska North Slope region from 1996–2019. The graph shows that while 

both crude and refined spills vary considerably, the trends in both follow the trends in oil production.

Interestingly, the number of crude and refined spills track each other reasonably well until about 2010. At 

that point the number of crude spills starts to drop dramatically while the number of refined spills 

meanders around in its normal range for several years. Both types of spills “bottom out” after 2015, but at 

different levels. The number of refined spills appears to have a floor value of about 10 spills per year and 

the number of crude spills appears to have stabilized at about 5 spills per year. However, the data doesn’t 

provide information on why this lower limit exists and it doesn’t provide insights into how it could 

change in the future.

Figure 9. Annual recorded number of oil spills for crude oil and refined oil plotted against the 

annual oil production for the Alaska North Slope region, 1996–2019

Figure 10 shows the annual volume of recorded crude and refined oil spills plotted against the oil 

production for the Alaska North Slope region in the years from 1996–2019. Neither the crude nor the 

refined spill data follows the trend in oil production. Once again, the 2006 Class A crude oil spill stands 

out.

 -

 100

 200

 300

 400

 500

 600

0

5

10

15

20

25

30

35

199619971998199920002001200220032004200520062007200820092010201120122013201420152016201720182019

Oil Production (million bbl)

Number of Spills

Number of Spills by Substance vs. Oil Production by Year

Crude Spills

Refined Spills

Production
21

Figure 10. Annual recorded volume of oil spills for crude oil and refined oil plotted against the 

annual oil production for the Alaska North Slope region, 1996–2019

5 SPILL RATE OCCURRENCE ESTIMATES

The overall purpose of this project was to develop a method to estimate oil spill rates based on 

independent variables. This section describes the process and results of that effort.

5.1 Annual Number of Spills Over Time

5.1.1 Screening Independent Variables

The first step in building an occurrence rate estimation model is to screen independent variables. The 

initial screening was done using scatterplots and Pearson Correlation Coefficients. Scatterplots give an 

indication graphically of whether or not a relationship exists between two variables. That relationship 

may be linear, quadratic, or some other shape. The Pearson Correlation Coefficient, also referred to as r, 

measures the strength of the observed linear relationship. A relationship that is perfectly linear will have 

an r value of 1 or -1, the sign indicating whether the relationship is direct or inverse. A completely 

uncorrelated pair of variables would have an r of zero. In real situations the observed r lies between these 

extremes.

The dependent variables screened were the total volume of oil spilled each year (Spill Vol.) and the total 

number of spills each year (No. Spills). The candidates for inclusion in a model as independent variables 

were: the annual volume (million cubic feet) of gas produced from gas wells (Gas Prod.), the annual 

volume (MMbbl) of oil produced from oil wells (Oil Prod.), the annual volume (million barrels) of water 

produced from oil wells (Water Prod.), and the average inflation adjusted price (US $) of Alaskan crude 

0

50

100

150

200

250

300

350

400

450

500

0

1000

2000

3000

4000

5000

6000

199619971998199920002001200220032004200520062007200820092010201120122013201420152016201720182019

Oil Production (million bbl)

Volume of Spills (bbl)

Volume of Spills by Substance vs. Oil Production by Year

Crude Spills

Refined Spills

Production
22

each year (Adj. Price). Pipeline mileage per year for the Alaska North Slope region was sought but there 

was not a comprehensive pipeline data source covering the time frame from 1996 to 2019. It was found to 

be a contributor to an occurrence model in an earlier study (Robertson et. al. 2013) and may be valuable 

in future efforts if the data can be sourced.

Figure 11 presents a scatterplot matrix, distribution, and the Pearson Correlation Coefficient for each 

variable considered for inclusion in the modeling process.

Figure 11. Scatterplot matrix, distribution, and the Pearson Correlation Coefficient for each 

variable considered for inclusion in the modeling process

Considering the p-values for the correlations between annual number of spills and each independent 

variable in Table 10, all Pearson Correlation Coefficient values, except adjusted price are significant at 

the 95% confidence level. All of these independent variables were kept in the initial screen process. 
23

Table 10. Pearson Correlation Coefficient and p-value for independent variables related to annual 

number and volume of spills recorded in Alaska North Slope, 1996–2019

Dependent Variable Annual number of 

spills

Independent Variable

Pearson 

Correlation 

Coefficient 

p-value

Gas Production -0.531 0.008

Oil Production 0.671 0.0003

Water Production 0.286 0.176

Adjusted Price -0.172 0.421

The results of this analysis indicate that:

1. The linear correlations were significantly stronger between the potential independent variables and 

the number of spills observed than between the volume of oil spilled. This further reinforces the 

decision to focus the regression work on explaining the number of spills, not the volume spilled.

2. It was ultimately decided that all of the potential independent variables merited inclusion in the 

initial screening models.

5.1.2 Modeling Approach

We used the following approach to select a suitable model:

1. All candidate independent variables were placed in a regression model as main effects (i.e. 

appearing alone as a term) and in all possible 2-way interactions (i.e. appearing as a term 

multiplying the variable with another variable).

2. The statistical software program “R” was used for regression modeling. R’s automatic step-wise 

variable selection procedure was run to find the model that minimized the Akaike Information 

Criteria (AIC statistic).

3. This procedure did not account for multicollinearity existing between the variables, so starting 

with the model suggested in the step-wise approach, a manual backward variable selection 

process was employed that removed terms based on which had the highest non-significant pvalue and/or the highest Variable Inflation Factor (VIF statistic). The goal was to keep only 

models for which all terms had a VIF less than 10.

5.2 Predicting Annual Spill Numbers from Crude Oil Production Using 

Linear Regression

Applying this modeling approach to the Alaska North Slope annual spill data resulted in a regression 

model with two independent variables: Oil Production and Adjusted Price. Other independent variables 

were eliminated through the modeling process due to strong multicollinearity existing between the 

variables.

The resulting linear regression model was: N_tot = -11.66664 + Oil_Prod. x 0.12482 + Adj_Price x 

0.18513

Where: N_tot = total annual number of spills for all spill types and classes

Oil_ Prod. = annual volume of crude oil produced from oil wells in million barrels

Adj_Price = Alaska North Slope crude oil price in US adjusted by Consumer Price Index 

to 2019.
24

The relevant statistics for this model are shown in Table 10.

Table 11. Statistics for the linear regression model predicting annual spills number from oil 

production and adjusted price

Coefficients Estimate Standard 

Error t value p-value Significance

Intercept -11.66664 10.24625 -1.139 0.268

Oil Prod. 0.12482 0.02427 5.144 0.000043 0.001

Adj. Price 0.18513 0.07610 2.433 0.024 0.05

Residual Standard Error 8.825 Degrees Freedom 21

Multiple R-squared 0.5706 Adjusted R-squared 0.5297

F-statistic 13.95 on 2 and 21 degrees of freedom

p-value 0.0001396

The model indicated that for every increase of one MMbbl of oil production, the total number of annual 

spills for all spill types and classes is expected to increase 0.12 units (recorded spills). The model says 

that, when controlling for inflation adjusted price of ANS crude oil, every increase of $1 per barrel will 

change the expected number of spills by 0.19 units. The model explains 53% of the variation observed in 

the annual number of spills. Figure 12 shows the model’s predicted value, the 95% confidence interval, 

and the 95% prediction interval for the range of oil production values studied. The confidence interval is 

the range that one would expect the mean value of the spill number to fall in 95% of the time when a 

given production level occurs a large number of times. The prediction interval is the range that one would 

expect any one value of the spill number to lie in for a given oil production level 95% of the time.
25

Figure 12. Predicted value, 95% confidence interval, and 95% prediction interval for the expected 

number of all oil spills for the range of oil production values studied with adjusted price 

of $75 per barrel for the Alaska North Slope region

As mentioned above, the plot above was created using a fixed adjusted price of $75 per bbl. However, our 

best model indicates that, while oil production is the most significant variable, changing prices also have

an impact on expected spills. The graph below shows how the expected number of spills shifts upward as 

price increases. This is likely due to multiple factors. One might be that in a higher price environment 

there are more funds available for construction and maintenance which can increase spills. It’s also 

possible that higher prices result in increased pressure to produce.
26

Figure 13. Predicted number of all oil spills for the range of oil production values studied at five 

different adjusted oil prices

The model’s calculated multivariate power was 0.99837. The model has exceptionally good power leading 

to high confidence in its explanatory value.

The model had reasonably normally distributed residuals (i.e. predicted value - observed value), and the 

equal variance assumption for linear regression was satisfied. Both of these factors indicate the validity of 

the model.

 

7 Where u = 2, v = 21, f2 = 1.3289, significance level = 0.5 (i.e. 95% confidence).
27

The model diagnostic software indicated two outliers (point 6 -2001 and point 16 - 2011) and one 

leverage point (point 1 - 1996). However, no points were considered to have exerted undue influence on

the model’s coefficients.

5.3 Predicting Annual Spill Volume from Crude Oil Production

Attempts to develop a regression model to estimate the annual volume of oil spills in the Alaska North 

Slope region failed for two reasons. First, as seen in Figure 14, the distribution of the dependent variable, 

annual volume of spills, has a strong positive skew which suggests that the normality assumption required 

for regression would be violated. Second, the individual correlations of the independent variables with 

Spill Volume are all weak as seen in Table 12 and Figure 14. No variable has a significant linear 

relationship with the total volume spilled at 95% confidence level, although the correlation with produced 

water was significant at the 90% confidence level.

Figure 14. Distribution of volume of recorded oil spill in the Alaska North Slope region, 1996–2019

0

1

2

3

 50

 250 450 650 850

 1,050 1,250 1,450 1,650 1,850 2,050 2,250 2,450 2,650 2,850 3,050 3,250 3,450 3,650 3,850 4,050 4,250 4,450 4,650 4,850 5,050 5,250 5,450 5,650

Count of Years

Reported Volume (bbl)

Frequency Distribution of Annual Volume of Spills

1996 - 2019
28

Table 12. Pearson Correlation Coefficient and p-value for independent variables related to annual 

volume of spills recorded in the Alaska North Slope region, 1996–2019

Independent Variable Pearson 

Correlation 

Coefficient

p-value

Gas Production -0.31 0.15

Oil Production 0.15 0.47

Water Production -0.38 0.07

Adjusted Price -0.003 0.988

Despite the weaknesses noted above, we attempted to develop a model to predict annual oil volume 

spilled. Using an automatic variable selection approach, we developed a multivariate model containing all 

independent variables. However, with an adjusted R-square of 0.024, only about 2% of the variability in 

annual spill volume was explained by the model. The p-value was 0.47 which is not significant at a 95%

confidence level. For these reasons, the model was deemed unusable to predict annual spill volume.

An alternate simulation approach was used to arrive at estimates of spill volumes. This approach used a 

bootstrap technique to estimate median spill volume for each size class and combined this with a Monte 

Carlo simulation to generate confidence intervals for the estimate of the number of spills of each class 

size. Bootstrapping is a commonly used statistical tool for establishing estimates of parameters along with 

the parameter’s expected distribution. This approach was used to estimate both the proportion and median

size of spills which would be expected to be in Classes A, B, C, or D. 

In a bootstrap model, the spills in the database are assumed to be random events with equal probability. 

The software then samples the dataset, with replacement, repeatedly for a sample of the same size as that 

actually observed. For each sample drawn, the proportion of spills of each spill size class is computed, as 

well as the median8 spill volume from the Class. The distribution of these sample statistics over a large 

number of trials represents the distribution that is expected to occur naturally. The results of the bootstrap 

estimate of the distribution of proportions for each spill class are shown in Figure 15.

A Monte Carlo simulation is used to estimate spill volume. A large number of trials were run in which 

randomly drawn records from the database were used to develop a model for number of spills. The 

prediction function generated an expected value for each trial. These spill number estimates are then 

combined with the estimated statistics for proportion and median size to come up with estimates of the 

number of spills expected from each size group and finally the total annual spill volume estimation. The 

procedure is outlined below:

1. The total number of spills expected is computed using the linear regression model with the 

adjusted price fixed at $75. Multiple realizations from a Monte Carlo simulation yield a 

distribution of the expected number at a given production level. This allows for the estimation of 

a confidence interval.

 

8 Because the distribution of spill volume is highly skewed, the median is a better estimate of the expected value 

than the mean.
29

2. The proportion by spill size class is estimated using the bootstrapped procedure. This leads to the 

estimate of how many spills were in each class.

3. The median size of a spill in each size class as determined by the bootstrap procedure is then 

applied.

The formula to estimate the total annual spilled volume is:

Vol_toty = Pred_N_toty x Prop_A x Med_A +Pred_N_toty x Prop_B x Med_B + Pred_N_toty x 

Prop_C x Med_C + Pred_N_toty x Prop_D x Med_D

Where: Pred_N_toty = total number of spills predicted for oil production level Y using 

the regression model with multiple realizations created via a Monte Carol 

simulation.

Prop_X = Proportion of spills from Class X estimated using the bootstrapped 

procedure

Med_X = Median spill size of Class X estimated using the bootstrapped 

procedure

This method was used for four levels of oil production: 150, 250, 350, and 500 MMbbl per year. Table 13 

presents the predicted number of spills from each of these production levels taken from the linear 

regression model presented in Section 5.2. Table 14 presents the median spill size by class and 

corresponding 95% confidence intervals. Table 15 presents the estimated number of spills of each size 

class and the total annual volume of spill predicted for each level of oil production.
30

Figure 15. Bootstrap estimate of the distribution of proportions for each spill class for Alaska 

North Slope Spills 1996–2019

Table 13. Expected annual number of spills and corresponding 95% confidence interval for four 

levels of oil production for the Alaska North Slope region with the adjusted crude oil 

price fixed at $75 per bbl

Oil 

Production

(MMbbl)

Expected Total 

Number of 

Spills

95% 

Confidence 

Interval

150 21.2 14.9 - 27.5

250 33.8 29.4 - 38.2

350 46.4 39.2 - 53.6

500 65.3 51.2 - 79.4

Proportion of Class A Spills Proportion of Class B Spills

Proportion of Class C Spills Proportion of Class D Spills
31

Table 14. Median spill size by class and corresponding 95% confidence interval for Alaska North 

Slope recorded spills 1996–2019 with the adjusted crude oil price fixed at $75 per bbl

Class Median Spill 

Size (bbl)

95% Confidence 

Interval

A > 1,000 bbl 5053.6 0 - 5,053.6

B > 200 & ≤ 1,000 bbl 321.4 260 - 607.14

C >10 & ≤200 bbl 25.6 23.4 - 34.9

D >1 & ≤10 bbl 2.4 2.1 - 2.4

Table 15. Expected annual number of spills and corresponding 95% confidence interval four size 

classes and four levels of oil production with the adjusted crude oil price fixed at $75 

per bbl; and estimated total annual volume of spills for the Alaska North Slope region 

predicted from the bootstrap method and Monte Carlo simulation

Oil Production

(MMbbl)

Class A

>1,000 bbl

Class B

>200 & ≤1,000 bbl

Class C

>10 & ≤200 bbl

Class D

>1 & ≤10 bbl All Classes

Expected 

Number 

of Spills

95% 

Confidence 

Interval

Expected 

Number 

of Spills

95% 

Confidence 

Interval

Expected 

Number 

of Spills

95% 

Confidence

Interval

Expected 

Number 

of Spills

95% 

Confidence 

Interval

Total 

Annual 

Volume 

(bbl)

95% 

Confidence 

Interval

150 0.0 0 - 0.1 0.2 0 - 0.5 3 0.4 - 5.9 18.4 2.9 - 35.2 334 33 - 897

250 0.0 0 - 0.2 0.3 0.1 - 0.7 4.7 2.0 - 7.7 29.1 14.0 - 45.5 526 168 - 1,260

350 0.1 0 - 0.2 0.5 0.2 - 0.9 6.4 3.5 - 9.8 39.8 24.1 - 56.9 719 266 - 1,633

500 0.1 0 - 0.3 0.7 0.2 - 1.2 9 5.6 - 13.1 55.9 37.4 - 75.9 1,010 395 - 2,256

Figure 16 shows the predicted annual volume of oil spilled for the four levels of annual oil production and 

associated 95% confidence intervals.
32

Figure 16. Bootstrap/Monte Carlo estimate of the predicted annual volume of oil spilled vs crude 

oil production for the Alaska North Slope region

5.4 Estimating Occurrence Rates by Oil Type

We now turn to estimating the occurrence rates for number and volume by oil type, either crude oil or 

refined oil.

5.4.1 Occurrence Rates for Number of Spills by Oil Type

Figure 9 depicts the number of recorded oil spills by substance type (crude and refined) versus the crude 

oil production by year. We attempted to develop models to predict the number of annual spills for each 

substance type.

Applying our modeling approach to the Alaska North Slope annual crude oil spill data resulted in a 

regression model with Oil Production as the single independent variable.

The resulting linear regression model was: N_crude_tot = -5.251565 + Oil Prod. x 0.065857

Where: N_crude_tot = total annual number of crude oil spills

Oil_ Prod. = annual volume of crude oil produced from oil wells in million barrels.

0

500

1,000

1,500

2,000

2,500

150 200 250 300 350 400 450 500

Annual Spill Volume (bbl)

Annual Oil Production (MMbbl)

Predicted Volume vs. Oil Production

Upper 95% Confidence Interval

Predicted Volume

Lower 95% Confidence Interval
33

The relevant statistics for this model are shown in Table 16. Interestingly, Adjusted Price did not provide 

a significant contribution to the model with crude oil spills only.9

Table 16. Statistics for the linear regression model predicting annual spills number of crude oil 

spills from oil production

Coefficients Estimate Standard 

Error T value p-value Significance

Intercept -5.251565 2.882137 -1.822 0.0821

Oil Prod. 0.065857 0.009908 6.647 1.11e-06 0.001

Multiple R-squared 0.6676 Degrees Freedom 22

F-statistic 18.0117 Adjusted R-squared 0.6525

p-value 1.105e-06 on 1 and 22 degrees of freedom

The model indicates that for every increase of one MMbbl of oil production the number of annual spills is 

expected to increase 0.066 units. The model explains 67% of the variation observed in the annual number 

of spills. Figure 17 shows the model’s predicted value, the 95% confidence interval, and the 95% 

prediction interval for the range of oil production values studied.

 

9 The p-value for Adjusted Price in a multivariate model was 0.207.
34

Figure 17. Predicted value, 95% confidence interval, and 95% prediction interval for the expected 

number of North Slope crude oil spills for the range of oil production values 

studied

The occurrence model to predict annual number of crude oil spills is very similar to the model developed 

to predict annual number of all types of oil. 

Regression techniques were applied to develop a model to predict the annual number of refined product 

oil spills. A univariate model was developed with oil production as an independent variable, but with an 

R-square of 0.078, only about 8% of the variability in annual spill numbers for refined product was 

explained by the model. The p-value was 0.185 which is not significant at a 95% confidence level. For 

these reasons, the model was deemed unusable to predict annual numbers of refined spills. There was no 

significant relationship between annual number of refined oil spills and any of the independent variables 

investigated.

The best method to predict the annual number of refined oil spills is the estimate of the mean number of 

refined oil spills which is 20.6 spill per year with a 95% confidence interval of 17.4 to 23.8. The skewness

of the distribution is -0.88 and the kurtosis of the distribution is -0.92, so the distribution is close enough 

to normal to allow for a mean as an estimate.
35

5.4.2 Occurrence Rates for Annual Volume of Spills by Oil Type

Figure 10 depicts the volume of recorded oil spill by substance type (crude and refined) versus the crude 

oil production by year. Neither the crude nor the refined spill volume data follows the trend in oil 

production, nor is the proportion of crude to refined spill volumes consistent over time or production 

level. In the absence of a valid model to predict the volume of either crude or refined spills, it was 

considered best to use the median of the annual spill volumes as an estimate. There is no significant linear 

relationship between oil production and spill volume for either crude or refined oil. So, an estimate of 

annual spill volume across all years is the best estimate.

The distributions for crude and refined annual oil spill volumes are highly skewed10, so the best estimate 

for annual spill volume by oil type is the median spill volume and the associated 95% percentile interval 

as presented in Table 17.

Table 17. Median annual spill volume and 95% Percentile Interval by oil type for North Slope oil 

spills, 1996–2019

Oil Type Median 

Spill 

Volume 

(bbl)

Lower 5% 

Percentile 

Interval

Upper 95% 

Percentile 

Interval

Crude 205.4 6.0 845.3

Refined 106.9 30.0 436.9

6 CONCLUSIONS

6.1 Limitations and Challenges of Occurrence Models

The models developed here do not address the causality of the relationships noted between the number of 

spills and independent variables explored, merely that they were unlikely to have occurred by chance. 

Therefore, caution should be used when applying statistical models for predictions in dissimilar 

circumstances. While these occurrence models performed adequately for predicting spill numbers in 

similar oil fields during a similar timeframe, using them to predict spills in other places or times could 

lead to predictions outside the confidence intervals due to differences in technology, industry practices, 

regulation and oversight, or other circumstances. 

Factors besides oil production volume contribute to oil spill occurrence rates as well. For example, 

because some spills are caused by human error, the number of work hours by people employed in the 

industry could be related to spill occurrence. Spill volume is also a function of the time it takes to detect 

 

10 Crude: kurtosis = 21.2 skewness = -0.39

 Refined: kurtosis = 6.0 skewness = 1.01
36

and stop a leak, which can depend on both technology and operator protocols or decisions. Therefore, 

advances in technology may have a big effect on volume spilled.

At the same time that using spill data from a specific location is important, it will always be challenging 

to model oil spill occurrences based on historical spills. Oil spills, especially large ones, are generally rare 

occurrences so datasets are prone to being small. This is further confounded, as was the case in this study, 

by changes in reporting requirements and record keeping. Industry practices also change, due to required 

or voluntary use of best practices, along with new technology. If we assume that the efforts of regulators 

and industry to reduce the number and size of spills will improve spill prevention over time, occurrence 

estimation models based on historic spills may over-predict future spills.

6.2 Occurrence Estimates for Spill Number

A variety of regression models were applied to explore the most accurate predictive approaches that could 

be used to estimate the number of spills based on various production variables. In some cases, strong 

predictive models were identified. In others, simpler estimating methods proved as accurate as regression 

modeling. 

While several predictive models were developed for overall spill occurrence rates, there were challenges 

when similar approaches were applied to size category subsets. The best model for predicting the annual 

total number of spills was a linear regression based upon annual volume of oil produced in MMbbl. The 

model equation was:

N_tot = -11.66664 + Oil_Prod. x 0.12482 + Adj_Price x 0.18513

Where: N_tot = total annual number of spills for all spill types and classes

Oil_ Prod. = annual volume of crude oil produced from oil wells in million barrels

Adj_Price = Alaska North Slope crude oil price in US adjusted by Consumer Price Index 

to 2019

The best model for predicting the annual total number of crude oil spills was a linear regression based 

upon annual volume of oil produced. The model equation was:

N_crude_tot = -5.251565 + Oil Prod. x 0.065857

Where: N_crude_tot = total annual number of crude oil spills

Oil_ Prod. = annual volume of crude oil produced from oil wells in million barrels

6.3 Occurrence Estimates for Spill Volume

We attempted to use regression to develop a model to predict total spill volume and spill volume by oil 

type without success. There is no significant linear relationship between any of the independent variables 

and the annual volume of oil spilled. So, an alternate approach was used to arrive at estimates of total spill 

volume using a bootstrap technique to estimate median spill volume for each size class and combined this 

with a Monte Carlo simulation to generate confidence intervals for the estimate of the number of spills of 

each class size. The resulting model was:

Vol_toty = Pred_N_toty x Prop_A x Med_A +Pred_N_toty x Prop_B x Med_B + Pred_N_toty x 

Prop_C x Med_C + Pred_N_toty x Prop_D x Med_D
37

This model predicts an annual spill volume of 526 bbl with a 95% Confidence Interval of 168 to 1,260

bbl at a 250 MMbbl per year level of oil production and an adjusted oil price of $75.

6.4 Recommendations

Occurrence estimates could be improved by using more independent variables, though in order to be 

useful these need to be variables that can be estimated or planned on for the future. For example, the 

volume of refined product utilized to construct and operate the oil production infrastructure might be a 

better predictor of refined oil spill than total oil production itself. It would be interesting to explore the 

annual number of working hours dedicated to oil exploration, development, and production as an 

independent variable based on the hypothesis that greater manhours spent in these activities would lead to 

an increase in spill numbers.

Most crude oil spills are the result of the loss-of-integrity of some portion of the oil production 

infrastructure. Examining the spill record for an individual facility (e.g. pipeline, tank, or processing 

plant) and then comparing similar facilities to establish occurrence rates by facility type may provide 

additional insight into occurrence rates.

Finally, as acknowledged, oil spill rate studies are limited by data quality. Reporting standards change 

over time and some data on potential independent variables are not recorded. 

7 REFERENCES

ABS Consulting Inc. 2016. 2016 Update of Occurrence Rates for Offshore Oil Spills. Prepared by ABS 

Consulting Inc. for USDOI, BOEM/BSEE. Sterling, VA: USDOI, BOEM/BSEE. 95 pp.

ABSG Consulting Inc. 2018. US Outer Continental Shelf Oil Spill Statistics. Arlington (VA): Prepared 

for US Department of the Interior, Bureau of Ocean Energy Management. OCS Study BOEM 2018-

006. 

Alaska Department of Environmental Conservation, Division of Spill Prevention and Response. 2003. 

Statewide Summary of Oil and Hazardous Substance Spill Data (Fiscal Years 1996–2002) 

Provisional Report.

Alaska Department of Environmental Conservation, Division of Spill Prevention and Response. 2007. 

Summary of Oil and Hazardous Substance Spills by Subarea (July 1, 1995 – June 30, 2005).

Alaska Department of Natural Resources, Division of Oil and Gas. 2019. North Slope Units Map. 

http://dog.dnr.alaska.gov/Document/4F4A45A4C6A4497CBAB4D2F7932F987F/12-3-

2019__North_Slope_Units_Region_Map?

Anderson CM, Labelle RP. 1990. Estimated occurrence rates for analysis of accidental oil spills on the 

U.S. Outer Continental Shelf. Oil & Chemical Pollution. 6:21-35. 

http://www.boemre.gov/eppd/sciences/osmp/pdfs/AndersonAndLaBelle/AndersonAndLaBelle1990.p

df
38

Anderson CM, Labelle RP. 1994. Comparative occurrence rates for offshore oil spills. Spill Science and 

Technology Bulletin. 1(2):131-141. 

http://www.boemre.gov/eppd/sciences/osmp/pdfs/AndersonAndLaBelle/Anderson_LaBelle1944.pdf

Anderson CM, Labelle RP. 2000. Update of comparative occurrence rates for offshore oil spills. Spill 

Science and Technology Bulletin. 6(5/6):303-321. http://www.boemre.gov/eppd/

Anderson CM, Mayes M, Labelle RP. 2012. Update of Occurrence Rates for Offshore Oil Spills. Sterling 

(VA): US Department of the Interior, Bureau of Ocean Energy Management. OCS Report BOEM 

2012-069.

Energy Information Administration (EIA). Alaska North Slope First Purchase Price. 2020 Aug 3. U.S. 

Energy Information Administration; [accessed 2020 Aug 7]. 

https://www.eia.gov/dnav/pet/hist/LeafHandler.ashx?n=PET&s=F005071__3&f=M

Lanfear KJ, Amstutz DE. 1983. A reexamination of occurrence rates for accidental oil spills on the U.S. 

Outer Continental Shelf. 1983 Oil Spill Conference. 

http://www.boemre.gov/eppd/sciences/osmp/pdfs/LanfearAndAmstutz1983.pdf

Robertson TL, DeCola E, Pearson L. 2010. Alaska North Slope spills analysis: Final report on North 

Slope Spills analysis and expert panel recommendations on mitigation measures. Report to Alaska 

Department of Environmental Conservation. 

http://www.dec.alaska.gov/spar/ipp/ara/documents/101123NSSAReportvSCREENwMAPS.pdf

Robertson TL, Campbell LK, Pearson L, Higman B. 2013. Oil spill occurrence rates for Alaska North 

Slope crude & refined oil Spills. Report to the Bureau of Ocean and Energy Management. 

https://www.boem.gov/sites/default/files/uploadedFiles/BOEM/BOEM_Newsroom/Library/Publicati

ons/2013-0205.pdf
39

8 APPENDICES

Appendix A: Collated Oil Spill Dataset
A-1

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -1 06/03/71 1071.43 A Refined: Other Refined: Other Vehicle Support Facility/Services Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -2 01/05/72 476.19 B Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -3 06/10/72 4.76 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Pipe or Line Over Pressure Mechanical Failure: Overpressure

NS -4 04/16/73 101.48 C Refined: Other Refined: Other Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -5 06/14/73 1.43 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -6 07/16/73 952.38 B Refined: Diesel Refined: Diesel Oil Exploration Oil Exploration Onshore Unknown Unknown Unknown Unknown

NS -7 11/27/74 1.19 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Unknown Unknown

NS -8 06/29/75 52.38 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -9 10/06/75 7.14 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -10 02/20/76 70.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -11 03/19/76 6.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -12 06/25/77 7.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Unknown Unknown Human Error, Overfill Human Error: Overfill

NS -13 07/19/77 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -14 07/25/77 4.40 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -15 08/03/77 3.14 D Crude Mixture Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -16 10/21/77 11.98 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -17 11/10/77 10.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -18 11/17/77 20.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -19 11/26/77 4.72 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Milne Point Unknown Human Error Human Error: Unknown

NS -20 12/04/77 3.77 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Milne Point Unknown Equipment Failure, Other Mechanical Failure: Other

NS -21 01/18/78 2.52 D Refined: Gasoline Refined: Other Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -22 01/31/78 9.43 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Unknown Unknown Equipment Failure, Other Mechanical Failure: Other

NS -23 02/03/78 7.55 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -24 02/19/78 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -25 02/25/78 3.14 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -26 03/07/78 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Corrosion Human Error: Unknown

NS -27 03/18/78 4.76 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -28 04/17/78 4.00 D Refined: Other Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -29 04/21/78 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -30 04/27/78 9.43 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -32 05/01/78 3.14 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -31 05/01/78 5.03 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -33 05/15/78 3.14 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Unknown Unknown Human Error, Overfill Human Error: Overfill

NS -34 06/09/78 1.26 D Crude Oil Crude Oil Oil Production Oil Production Unknown Milne Point Unknown Over Pressure Mechanical Failure: Overpressure

NS -35 06/21/78 2.38 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -36 06/28/78 15.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -37 07/09/78 6.29 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Unknown Unknown

NS -38 08/03/78 1.26 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -39 08/05/78 11.90 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -40 08/10/78 6.29 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -41 08/22/78 5.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Unknown Unknown

NS -42 11/17/78 1.31 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -43 12/04/78 7.55 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -44 12/05/78 2.52 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -45 01/15/79 8.81 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -46 02/11/79 23.81 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -47 02/14/79 4.40 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -48 02/23/79 1.57 D Refined: Diesel Mixture Refined: Diesel Vehicle Support Facility/Services Unknown Prudhoe Bay Unknown Human Error, Vehicle Accidents Human Error: Unknown

NS -49 03/12/79 1.20 D Refined: Hydraulic Oil Refined: Other Vehicle Support Facility/Services Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -50 03/25/79 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -51 04/07/79 10.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -52 04/10/79 3.14 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -53 04/22/79 1.89 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -54 04/29/79 3.14 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -55 05/12/79 3.14 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -56 05/26/79 1.26 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -57 06/28/79 6.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Unknown Unknown

NS -58 06/29/79 1.90 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Unknown Unknown

NS -59 07/04/79 10.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -60 07/07/79 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -61 07/09/79 1.26 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow
A-2

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -62 07/14/79 1.50 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -63 07/26/79 1.69 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -64 08/11/79 9.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -65 08/29/79 5.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Unknown Unknown

NS -66 09/02/79 1.89 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -67 09/04/79 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -68 09/25/79 6.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -69 11/09/79 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -70 11/11/79 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -71 01/03/80 4.76 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -72 01/04/80 45.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -73 03/20/80 4.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -74 04/06/80 2.38 D Refined: Other Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -75 04/29/80 1.19 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -76 05/07/80 4.76 D Crude Oil Crude Oil Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -78 06/04/80 10.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -77 06/04/80 10.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -79 06/05/80 5.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -80 06/18/80 1.19 D Crude Mixture Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -81 06/19/80 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -82 07/01/80 4.76 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -83 08/08/80 5.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -84 08/22/80 6.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -85 08/23/80 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -86 09/03/80 20.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -87 10/23/80 2.38 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -88 10/31/80 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -89 11/07/80 1.79 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Unknown Prudhoe Bay Unknown Unknown Unknown

NS -90 11/11/80 15.00 C Refined: Oil 

Drilling Mud

Refined: Other Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -91 11/16/80 4.76 D Refined: Gasoline Refined: Other Support Facility/Services Support Facility/Services Unknown Unknown Unknown Unknown Unknown

NS -92 11/21/80 102.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -93 12/06/80 3.57 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Corrosion Human Error: Unknown

NS -94 12/18/80 6.00 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Unknown Unknown

NS -95 12/30/80 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -96 01/12/81 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -97 01/14/81 23.81 C Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Unknown Unknown

NS -98 01/19/81 10.00 D Refined: Oil 

Drilling Mud

Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -99 01/20/81 10.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -100 01/21/81 2.00 D Refined: Other Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -101 01/25/81 4.00 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Unknown Unknown

NS -102 02/06/81 22.14 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Vehicle Accidents Human Error: Unknown

NS -103 02/18/81 16.67 C Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Unknown Unknown Unknown Unknown

NS -104 02/19/81 1.79 D Refined: Other Refined: Other Unknown Unknown Unknown Unknown Unknown Unknown Unknown

NS -105 02/23/81 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -106 03/19/81 4.76 D Refined: Other Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -107 03/21/81 1.19 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Unknown Unknown Unknown Unknown

NS -108 04/03/81 3.00 D Refined: Oil 

Drilling Mud

Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -109 04/09/81 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -110 04/13/81 1.43 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Vehicle Accidents Human Error: Unknown

NS -111 04/16/81 1.43 D Refined: Other Refined: Other Support Facility/Services Support Facility/Services Unknown Unknown Unknown Unknown Unknown

NS -112 04/24/81 101.95 C Refined: Gasoline Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -114 04/25/81 2.86 D Refined: Oil 

Drilling Mud

Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -113 04/25/81 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -115 04/26/81 14.29 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -116 04/26/81 10.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -117 04/29/81 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -118 05/01/81 1.43 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown
A-3

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -119 05/04/81 14.29 C Refined: Gasoline Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -120 05/08/81 2.00 D Refined: Oil 

Drilling Mud

Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -121 05/15/81 1.19 D Refined: Other Refined: Other Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -122 05/21/81 1.19 D Refined: Other Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -123 05/27/81 1.19 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -124 05/30/81 2.98 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -125 05/31/81 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -126 06/07/81 7.14 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -128 06/08/81 23.81 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -127 06/08/81 71.43 C Refined: Hydraulic Oil Refined: Other Oil Exploration Oil Exploration Unknown Unknown Unknown Unknown Unknown

NS -129 06/10/81 2.12 D Crude Mixture Crude Oil Unknown Unknown Unknown Unknown Unknown Unknown Unknown

NS -130 06/11/81 23.81 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -131 06/21/81 3.57 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -132 06/22/81 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Unknown Unknown

NS -133 06/25/81 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Unknown Unknown

NS -134 07/24/81 2.02 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Unknown Unknown Human Error, Overfill Human Error: Overfill

NS -135 08/04/81 4.76 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -136 08/07/81 23.81 C Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Unknown Unknown Unknown Unknown

NS -137 08/09/81 40.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Human Error Human Error: Unknown

NS -138 08/10/81 21.43 C Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Unknown Unknown

NS -139 08/19/81 1.55 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Unknown Unknown

NS -140 08/22/81 450.00 B Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -142 09/04/81 2.38 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -141 09/04/81 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -143 09/09/81 1.19 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Unknown Unknown

NS -144 10/06/81 59.52 C Refined: Other Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -145 10/26/81 10.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Over Pressure Mechanical Failure: Overpressure

NS -146 10/29/81 1.31 D Refined: Other Refined: Other Oil Exploration Oil Exploration Unknown Unknown Unknown Unknown Unknown

NS -148 11/05/81 1.19 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -147 11/05/81 1.19 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Unknown Unknown

NS -149 11/13/81 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -150 11/15/81 3.57 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -151 11/25/81 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -152 12/01/81 7.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Milne Point Unknown Unknown Unknown

NS -153 12/02/81 47.52 C Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Unknown Unknown

NS -154 12/06/81 23.81 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Human Error Human Error: Unknown

NS -155 12/07/81 1.67 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -156 12/10/81 1.43 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Unknown Unknown Unknown Unknown

NS -157 12/19/81 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -158 12/23/81 50.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Unknown Unknown

NS -159 12/30/81 2.38 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -160 01/13/82 1.19 D Refined: Other Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -161 01/20/82 2.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Unknown Unknown

NS -162 01/20/82 1.67 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -163 02/13/82 11.90 C Refined: Other Refined: Other Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -164 02/27/82 1.62 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -165 03/04/82 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -166 03/07/82 4.76 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -167 03/08/82 4.76 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -168 03/14/82 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -169 03/23/82 4.76 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -171 04/02/82 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -170 04/02/82 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -172 04/14/82 3.00 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Human Error, Vehicle Accidents Human Error: Unknown

NS -173 04/15/82 4.76 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -174 04/30/82 60.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -175 05/12/82 42.86 C Refined: Other Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -176 05/14/82 1.79 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -177 05/31/82 4.76 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Unknown Unknown Human Error Human Error: Unknown

NS -178 06/03/82 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown
A-4

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -179 06/07/82 3.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Unknown Unknown

NS -180 06/17/82 1.43 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -181 06/19/82 11.90 C Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -182 06/22/82 3.10 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -183 06/24/82 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -184 06/26/82 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -185 07/06/82 1.90 D Refined: Diesel Refined: Diesel Oil Exploration Oil Exploration Unknown Unknown Unknown Equipment Failure, Other Mechanical Failure: Other

NS -186 08/09/82 1.19 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -187 08/09/82 2.86 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -188 08/13/82 1.19 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -189 08/15/82 1.19 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -190 08/20/82 2.86 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -191 08/23/82 2.38 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -192 09/27/82 1.43 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -193 10/17/82 25.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -194 10/18/82 4.76 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Milne Point Unknown Equipment Failure, Other Mechanical Failure: Other

NS -195 10/26/82 7.14 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -196 10/31/82 200.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -197 11/01/82 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -198 11/04/82 30.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -199 11/07/82 10.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -200 11/09/82 25.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -201 11/10/82 2.38 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -202 11/15/82 1.79 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -203 11/18/82 4.76 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -204 11/21/82 45.00 C Refined: Gasoline Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -205 11/22/82 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -206 12/03/82 1.19 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -207 12/04/82 5.95 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -208 12/12/82 25.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -209 12/23/82 10.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -210 12/27/82 15.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Unknown Unknown

NS -211 01/27/83 10.00 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Unknown Unknown

NS -212 01/28/83 62.00 C Refined: Gasoline Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -213 02/09/83 1.19 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -214 03/31/83 54.76 C Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Human Error Human Error: Unknown

NS -215 04/24/83 3.57 D Refined: Other Refined: Other Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -216 05/12/83 23.81 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -217 05/16/83 1.07 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -218 05/17/83 1.31 D Refined: Hydraulic Oil Refined: Other Support Facility/Services Support Facility/Services Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -219 05/18/83 1.43 D Refined: Other Refined: Other Vehicle Support Facility/Services Onshore Unknown Unknown Human Error, Vehicle Accidents Human Error: Unknown

NS -220 05/25/83 4.76 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -221 05/29/83 5.95 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -222 06/02/83 2.38 D Refined: Diesel Refined: Diesel Unknown Unknown Onshore Unknown Unknown Human Error, Overfill Human Error: Overfill

NS -223 06/03/83 5.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -224 06/09/83 4.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -225 06/12/83 11.90 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -226 06/13/83 47.62 C Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -227 06/13/83 2.38 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -228 06/19/83 114.29 C Refined: Diesel Refined: Diesel Unknown Unknown Onshore Unknown Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -229 06/25/83 1.19 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Unknown Unknown

NS -230 06/25/83 5.00 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Prudhoe Bay Unknown Unknown Unknown

NS -231 07/05/83 11.90 C Refined: Other Refined: Other Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -232 07/08/83 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -233 07/08/83 1.79 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -235 07/10/83 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -234 07/10/83 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Unknown Unknown

NS -236 07/11/83 5.00 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Unknown Unknown

NS -237 07/13/83 4.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -238 07/28/83 1.79 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Unknown Unknown Human Error Human Error: Unknown

NS -239 08/03/83 4.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Unknown Unknown Unknown
A-5

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -240 08/16/83 2.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Milne Point Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -241 08/19/83 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -243 08/22/83 1.79 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -242 08/22/83 2.38 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Unknown Kuparuk River Unknown Unknown Unknown

NS -244 08/25/83 2.38 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Unknown Unknown

NS -245 08/27/83 10.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Unknown Unknown

NS -246 09/06/83 24.00 C Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Human Error Human Error: Unknown

NS -247 09/06/83 2.38 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -248 09/23/83 9.52 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -249 09/27/83 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -250 10/19/83 2.38 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -251 10/28/83 7.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -252 11/01/83 2.38 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -253 11/01/83 1.55 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -254 11/02/83 15.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -255 11/04/83 23.81 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -256 11/12/83 1.67 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -257 11/15/83 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -258 11/16/83 35.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -259 11/22/83 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Unknown Unknown

NS -260 11/23/83 3.90 D Refined: Hydraulic Oil Refined: Other Unknown Unknown Unknown Unknown Unknown Equipment Failure, Other Mechanical Failure: Other

NS -261 11/28/83 3.10 D Refined: Hydraulic Oil Refined: Other Unknown Unknown Unknown Unknown Unknown Equipment Failure, Other Mechanical Failure: Other

NS -262 11/29/83 23.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -263 12/05/83 1.19 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Unknown Prudhoe Bay Unknown Unknown Unknown

NS -264 12/18/83 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -265 01/03/84 60.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -266 01/03/84 3.57 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -267 02/06/84 9.52 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Equipment Failure, Other Mechanical Failure: Other

NS -268 02/11/84 1.50 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Equipment Failure, Other Mechanical Failure: Other

NS -269 02/19/84 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Unknown Unknown Human Error Human Error: Unknown

NS -270 03/04/84 6.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -271 03/04/84 3.57 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -272 03/12/84 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -273 03/17/84 38.10 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -274 04/08/84 10.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -275 04/13/84 10.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -276 05/18/84 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -277 05/24/84 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -278 06/10/84 3.00 D Crude Mixture Crude Oil Oil Production Oil Production Unknown Unknown Unknown Equipment Failure, Other Mechanical Failure: Other

NS -279 06/11/84 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -280 06/14/84 5.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -281 06/18/84 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Unknown Unknown

NS -282 06/30/84 1.19 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Unknown Unknown Unknown Unknown

NS -283 07/03/84 1.19 D Refined: Other Refined: Other Support Facility/Services Support Facility/Services Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -284 07/20/84 3.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Unknown Unknown

NS -285 07/26/84 5.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Unknown Unknown

NS -286 08/09/84 20.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -287 08/19/84 10.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -288 09/10/84 10.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -289 10/09/84 30.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -290 11/06/84 125.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -291 12/22/84 5.00 D Refined: Gasoline Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -292 01/13/85 2.14 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -293 01/22/85 2.62 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -294 01/31/85 2.14 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -295 02/08/85 1.19 D Crude Oil Crude Oil Vehicle Support Facility/Services Unknown Unknown Unknown Human Error, Overfill Human Error: Overfill

NS -296 02/10/85 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Human Error Human Error: Unknown

NS -297 02/11/85 10.48 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -298 02/13/85 2.62 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -299 02/14/85 1.67 D Refined: Hydraulic Oil Refined: Other Unknown Unknown Unknown Unknown Unknown Equipment Failure, Other Mechanical Failure: Other

NS -300 02/16/85 2.14 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Human Error, Overfill Human Error: Overfill
A-6

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -301 03/02/85 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Unknown Unknown Unknown

NS -302 03/16/85 1.57 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Human Error Human Error: Unknown

NS -303 03/19/85 20.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -304 03/19/85 20.95 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Milne Point Unknown Equipment Failure, Other Mechanical Failure: Other

NS -305 03/22/85 7.14 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -306 03/30/85 1.05 D Crude Oil Crude Oil Oil Production Oil Production Unknown Unknown Unknown Unknown Unknown

NS -307 04/03/85 10.48 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Unknown Unknown Unknown

NS -308 04/07/85 1.43 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -309 04/07/85 10.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -310 04/08/85 2.10 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -311 04/09/85 1.05 D Crude Oil Crude Oil Oil Production Oil Production Unknown Unknown Unknown Unknown Unknown

NS -312 04/10/85 2.14 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -313 04/10/85 27.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -314 04/18/85 1.90 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -315 04/22/85 5.24 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -316 04/22/85 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -317 04/22/85 3.81 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -318 04/27/85 9.52 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Prudhoe Bay Unknown Unknown Unknown

NS -320 04/30/85 7.14 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -319 04/30/85 15.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Human Error Human Error: Unknown

NS -321 04/30/85 5.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Milne Point Unknown Equipment Failure, Other Mechanical Failure: Other

NS -322 05/03/85 5.95 D Crude Oil Crude Oil Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -323 05/08/85 1.90 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -324 05/11/85 2.86 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Milne Point Unknown Equipment Failure, Other Mechanical Failure: Other

NS -325 05/13/85 5.95 D Crude Oil Crude Oil Oil Production Oil Production Unknown Unknown Pipe or Line Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -326 05/13/85 2.98 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Milne Point Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -327 05/18/85 25.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -328 05/22/85 95.24 C Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Equipment Failure, Other Mechanical Failure: Other

NS -329 05/25/85 50.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Unknown Unknown Human Error, Vehicle Accidents Human Error: Unknown

NS -330 05/31/85 2.38 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -332 06/02/85 238.10 B Crude Oil Crude Oil Support Facility/Services Support Facility/Services Onshore Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -333 06/02/85 1.19 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -331 06/02/85 23.81 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -334 06/03/85 1.50 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -335 06/05/85 1.19 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -336 06/17/85 1.19 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -337 06/18/85 3.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Milne Point Unknown Human Error, Overfill Human Error: Overfill

NS -338 06/30/85 1.19 D Refined: Other Refined: Other Unknown Unknown Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -339 07/02/85 1.43 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -340 07/12/85 20.24 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Milne Point Unknown Equipment Failure, Other Mechanical Failure: Other

NS -341 07/15/85 2.02 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -342 07/17/85 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -343 07/17/85 4.76 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -344 07/19/85 1.19 D Refined: Diesel Mixture Refined: Diesel Unknown Unknown Onshore Unknown Unknown Human Error Human Error: Unknown

NS -345 07/22/85 5.95 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -346 07/23/85 1.19 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -347 08/01/85 1.07 D Refined: Gasoline Refined: Other Unknown Unknown Onshore Unknown Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -348 08/08/85 2.38 D Refined: Other Refined: Other Support Facility/Services Support Facility/Services Onshore Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -349 08/17/85 2.38 D Refined: Other Refined: Other Oil Production Oil Production Unknown Milne Point Unknown Human Error Human Error: Unknown

NS -350 08/22/85 1.79 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Unknown Unknown

NS -351 08/24/85 4.76 D Refined: Other Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -352 08/31/85 5.00 D Refined: Oil 

Drilling Mud

Refined: Other Oil Production Oil Production Unknown Milne Point Unknown Unknown Unknown

NS -353 09/01/85 5.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -354 09/02/85 2.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -355 09/02/85 4.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -356 09/06/85 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Human Error Human Error: Unknown

NS -357 09/15/85 4.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -358 09/19/85 15.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -359 09/21/85 3.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -360 10/03/85 3.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Milne Point Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal
A-7

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -361 10/05/85 2.98 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -362 10/05/85 3.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Milne Point Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -363 10/06/85 3.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Unknown Human Error Human Error: Unknown

NS -364 10/06/85 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -365 10/12/85 14.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -366 11/02/85 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -367 11/03/85 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -368 11/06/85 2.98 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -369 11/14/85 250.00 B Refined: Gasoline Refined: Other Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -370 11/15/85 175.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Milne Point Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -371 11/18/85 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -372 11/21/85 4.76 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -373 11/24/85 7.00 D Refined: Oil 

Drilling Mud

Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -374 11/25/85 10.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -375 11/27/85 1.43 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -376 11/29/85 1.31 D Refined: Hydraulic Oil Refined: Other Vehicle Support Facility/Services Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -377 12/01/85 1.31 D Refined: Other Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -378 12/03/85 4.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -379 12/05/85 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Human Error Human Error: Unknown

NS -380 12/06/85 44.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -381 12/11/85 1.19 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -382 12/12/85 3.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -384 12/15/85 40.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -383 12/15/85 1.31 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Unknown Kuparuk River Unknown Unknown Unknown

NS -386 12/16/85 1.07 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -385 12/16/85 11.90 C Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Unknown Unknown

NS -387 12/22/85 10.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -388 12/26/85 1.50 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Unknown Unknown Human Error, Overfill Human Error: Overfill

NS -389 12/27/85 4.76 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -390 12/28/85 30.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -391 12/29/85 1.19 D Crude Oil Crude Oil Oil Production Oil Production Unknown Unknown Unknown Over Pressure Mechanical Failure: Overpressure

NS -392 01/02/86 40.21 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -393 01/03/86 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Unknown Unknown

NS -394 01/04/86 1.19 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Unknown Milne Point Unknown Human Error, Vehicle Accidents Human Error: Unknown

NS -395 01/08/86 118.02 C Refined: Gasoline Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -396 01/11/86 1.90 D Crude Oil Crude Oil Oil Production Oil Production Unknown Unknown Unknown Unknown Unknown

NS -397 01/13/86 1.90 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -398 01/17/86 5.00 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -399 01/21/86 2.38 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Milne Point Unknown Human Error, Overfill Human Error: Overfill

NS -400 01/23/86 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -401 01/30/86 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Human Error Human Error: Unknown

NS -402 02/02/86 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -403 02/14/86 7.00 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -404 02/15/86 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -405 02/17/86 7.50 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -406 02/18/86 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -407 02/21/86 7.14 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Equipment Failure, Other Mechanical Failure: Other

NS -408 03/02/86 80.95 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -409 03/02/86 4.00 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Human Error Human Error: Unknown

NS -410 03/10/86 10.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Human Error Human Error: Unknown

NS -411 03/10/86 4.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -412 03/10/86 3.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Unknown Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -413 03/12/86 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -414 03/15/86 3.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Unknown Unknown

NS -415 03/18/86 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Unknown Unknown

NS -416 03/20/86 2.00 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -417 03/27/86 6.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -418 03/28/86 7.31 D Refined: Gasoline Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -419 04/02/86 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -420 04/05/86 50.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown
A-8

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -421 04/07/86 19.05 C Crude Mixture Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -422 04/09/86 2.50 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Human Error Human Error: Unknown

NS -423 04/10/86 4.76 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -424 04/11/86 3.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Human Error Human Error: Unknown

NS -425 04/20/86 2.55 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -426 04/22/86 4.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -427 04/23/86 47.62 C Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Unknown Unknown

NS -428 04/29/86 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -429 05/01/86 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -430 05/11/86 6.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -431 05/21/86 5.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -432 05/25/86 5.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -433 05/26/86 4.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -434 05/27/86 5.95 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Unknown Unknown

NS -435 05/30/86 3.57 D Refined: Gasoline Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -436 05/31/86 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -437 06/04/86 2.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -438 06/07/86 2.00 D Refined: Other Refined: Other Support Facility/Services Support Facility/Services Onshore Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -439 06/09/86 3.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Over Pressure Mechanical Failure: Overpressure

NS -440 06/10/86 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -441 06/11/86 4.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -442 06/18/86 5.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -443 06/20/86 2.00 D Refined: Other Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -444 06/27/86 11.90 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Unknown Unknown

NS -445 06/29/86 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -446 07/06/86 3.00 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -447 07/06/86 4.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -448 07/15/86 4.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -449 07/17/86 1.43 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -450 07/24/86 5.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -451 07/31/86 2.38 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -452 08/04/86 1.19 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -453 08/09/86 15.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -454 08/10/86 4.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -455 08/12/86 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -456 08/25/86 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -457 08/31/86 20.00 C Refined: Oil 

Drilling Mud

Refined: Other Oil Production Oil Production Onshore Endicott Unknown Equipment Failure, Other Mechanical Failure: Other

NS -458 09/01/86 2.50 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -459 09/09/86 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -460 09/15/86 20.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Milne Point Unknown Human Error Human Error: Unknown

NS -461 09/25/86 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -462 09/26/86 1.19 D Refined: Gasoline Refined: Other Support Facility/Services Support Facility/Services Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -463 09/29/86 30.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Milne Point Unknown Human Error Human Error: Unknown

NS -464 10/07/86 2.12 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -465 10/16/86 100.00 C Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -466 10/22/86 4.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -467 10/22/86 2.00 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Unknown Kuparuk River Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -468 11/04/86 3.00 D Refined: Oil 

Drilling Mud

Refined: Other Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -469 11/07/86 120.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -470 11/10/86 25.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Milne Point Unknown Human Error Human Error: Unknown

NS -471 11/11/86 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -472 11/23/86 1.19 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Human Error, Vehicle Accidents Human Error: Unknown

NS -473 11/29/86 20.00 C Refined: Oil 

Drilling Mud

Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -474 12/13/86 55.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -475 12/19/86 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -476 12/21/86 1.50 D Crude Mixture Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -477 12/27/86 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -478 12/28/86 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Human Error, Overfill Human Error: Overfill
A-9

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -479 01/05/87 357.14 B Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -480 01/10/87 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -481 01/13/87 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -482 01/16/87 2.12 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -483 02/02/87 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -484 02/09/87 1.50 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -485 02/12/87 5.24 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -486 02/23/87 4.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -487 02/28/87 2.00 D Refined: Diesel Mixture Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -488 03/04/87 3.00 D Crude Mixture Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -489 03/06/87 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -490 03/10/87 1.43 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -491 03/25/87 120.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -492 03/31/87 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -493 04/03/87 1.07 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -494 04/24/87 1.79 D Refined: Diesel Refined: Diesel Unknown Unknown Onshore Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -495 04/29/87 4.76 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Prudhoe Bay Unknown Unknown Unknown

NS -496 05/08/87 1.31 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Human Error Human Error: Unknown

NS -497 05/11/87 2.00 D Refined: Diesel Mixture Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -498 05/24/87 1.19 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Endicott Unknown Equipment Failure, Other Mechanical Failure: Other

NS -499 06/08/87 2.38 D Refined: Diesel Mixture Refined: Diesel Support Facility/Services Support Facility/Services Unknown Unknown Unknown Unknown Unknown

NS -500 06/14/87 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Unknown Unknown Human Error Human Error: Unknown

NS -501 06/16/87 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -502 06/19/87 2.00 D Crude Mixture Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -503 06/22/87 10.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -504 06/22/87 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -505 06/30/87 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -506 07/15/87 4.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -507 07/17/87 1.19 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -508 07/19/87 1.79 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -510 07/20/87 2.38 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -509 07/20/87 2.62 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Unknown Unknown Unknown Unknown

NS -511 07/22/87 3.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Human Error Human Error: Unknown

NS -512 07/24/87 1.19 D Crude Mixture Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -513 07/25/87 1.50 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -514 07/28/87 1.19 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -515 07/29/87 20.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Human Error Human Error: Unknown

NS -516 08/04/87 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -517 08/04/87 2.00 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Human Error Human Error: Unknown

NS -518 08/07/87 1.19 D Refined: Other Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -519 08/10/87 2.38 D Refined: Other Refined: Other Support Facility/Services Support Facility/Services Unknown Unknown Unknown Unknown Unknown

NS -520 08/16/87 50.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -521 08/24/87 1.19 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -522 09/14/87 19.64 C Crude Mixture Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -523 09/16/87 2.50 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -524 09/19/87 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Unknown Pipe or Line Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -525 09/19/87 10.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -526 09/20/87 60.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -527 09/22/87 3.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -528 09/27/87 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -529 09/28/87 4.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -530 10/01/87 2.00 D Refined: Other Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -531 10/03/87 1.19 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -532 10/09/87 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -533 10/10/87 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Human Error Human Error: Unknown

NS -534 10/11/87 1.79 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -535 10/13/87 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -536 10/14/87 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -537 10/15/87 6.00 D Refined: Oil 

Drilling Mud

Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -538 10/31/87 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Human Error, Overfill Human Error: Overfill
A-10

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -539 11/08/87 11.90 C Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -540 11/12/87 10.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -541 11/14/87 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -542 11/25/87 9.52 D Crude Oil Crude Oil Oil Production Oil Production Unknown Unknown Unknown Human Error, Overfill Human Error: Overfill

NS -543 11/25/87 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -544 11/26/87 1.90 D Crude Mixture Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Human Error Human Error: Unknown

NS -545 12/01/87 7.14 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -546 12/30/87 9.50 D Refined: Gasoline Refined: Other Oil Production Oil Production Unknown Unknown Unknown Equipment Failure, Other Mechanical Failure: Other

NS -547 01/20/88 12.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -548 01/21/88 10.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -549 01/25/88 1.50 D Crude Mixture Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -550 01/30/88 15.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -551 02/05/88 1.19 D Crude Mixture Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -552 02/05/88 1.19 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -553 02/08/88 287.14 B Crude Oil Crude Oil Oil Production Oil Production Unknown Endicott Unknown Unknown Unknown

NS -554 02/12/88 25.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Pipe or Line Corrosion Human Error: Unknown

NS -555 02/14/88 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Human Error Human Error: Unknown

NS -556 02/14/88 1.43 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -557 02/19/88 1.90 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -558 02/27/88 1.07 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -559 02/28/88 1.19 D Refined: Other Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -560 03/06/88 2.62 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -561 03/07/88 2.38 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -562 03/17/88 5.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -563 03/19/88 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -564 03/30/88 281.00 B Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Corrosion Human Error: Unknown

NS -565 04/01/88 2.50 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -566 04/03/88 1.19 D Refined: Other Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -567 04/04/88 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -568 04/07/88 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -569 04/14/88 5.00 D Crude Mixture Crude Oil Oil Production Oil Production Unknown Unknown Pipe or Line Unknown Unknown

NS -570 04/19/88 3.57 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Human Error, Overfill Human Error: Overfill

NS -571 04/22/88 1.43 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Endicott Unknown Equipment Failure, Other Mechanical Failure: Other

NS -572 04/24/88 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -573 05/02/88 20.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -574 05/03/88 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -575 05/07/88 1.90 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -576 05/15/88 1.19 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -577 05/16/88 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -578 05/17/88 1.43 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -579 05/21/88 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -580 05/23/88 1.90 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -581 06/01/88 4.76 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -582 06/05/88 1.19 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -583 06/09/88 2.38 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -584 06/11/88 5.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Unknown Unknown Human Error, Overfill Human Error: Overfill

NS -585 06/12/88 1.19 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Human Error Human Error: Unknown

NS -586 06/12/88 7.62 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -587 06/13/88 1.50 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -588 06/16/88 1.19 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Unknown Unknown Equipment Failure, Other Mechanical Failure: Other

NS -589 06/19/88 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Unknown Unknown

NS -590 06/19/88 7.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -591 06/21/88 3.00 D Crude Mixture Crude Oil Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Human Error, Vehicle Accidents Human Error: Unknown

NS -592 06/23/88 4.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -593 06/25/88 2.38 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -594 06/26/88 3.00 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -595 06/28/88 1.67 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -596 06/29/88 1.43 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -597 07/01/88 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -598 07/02/88 3.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -599 07/04/88 3.14 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill
A-11

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -600 07/05/88 3.00 D Crude Mixture Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -601 07/09/88 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -603 07/11/88 1.50 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -602 07/11/88 5.95 D Refined: Other Refined: Other Unknown Unknown Unknown Unknown Unknown Unknown Unknown

NS -604 07/18/88 2.38 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -605 07/20/88 7.14 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -606 07/23/88 2.38 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Unknown Unknown Human Error Human Error: Unknown

NS -607 08/02/88 1.14 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -608 08/03/88 1.67 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -609 08/06/88 1.07 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -610 08/10/88 30.00 C Crude Mixture Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -612 08/16/88 1.07 D Refined: Hydraulic Oil Refined: Other Support Facility/Services Support Facility/Services Onshore Unknown Unknown Equipment Failure, Other Mechanical Failure: Other

NS -611 08/16/88 50.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -613 08/20/88 2.00 D Crude Mixture Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -614 08/23/88 5.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -615 08/29/88 1.19 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -617 09/10/88 30.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -616 09/10/88 1.19 D Crude Oil Crude Oil Oil Production Oil Production Unknown Endicott Unknown Unknown Unknown

NS -618 09/11/88 2.38 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -619 09/15/88 7.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -620 09/30/88 10.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Unknown Unknown

NS -621 10/01/88 9.52 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Unknown Unknown

NS -622 10/10/88 2.38 D Refined: Other Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -623 10/13/88 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -624 10/13/88 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -625 10/15/88 6.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Unknown Unknown

NS -626 10/17/88 2.17 D Refined: Gasoline Refined: Other Unknown Unknown Unknown Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -627 10/19/88 4.76 D Refined: Gasoline Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -628 10/20/88 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -630 10/25/88 1.19 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -629 10/25/88 1.31 D Refined: Diesel Mixture Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Unknown Unknown

NS -631 10/26/88 1.67 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -632 10/29/88 71.24 C Crude Oil Crude Oil Oil Production Oil Production Unknown Unknown Unknown Human Error Human Error: Unknown

NS -633 11/03/88 1.19 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Onshore Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -634 11/04/88 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -636 11/06/88 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -635 11/06/88 1.43 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -637 11/11/88 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Corrosion Human Error: Unknown

NS -638 11/11/88 1.19 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -639 11/12/88 1.79 D Refined: Other Refined: Other Support Facility/Services Support Facility/Services Unknown Unknown Unknown Unknown Unknown

NS -640 11/18/88 3.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Corrosion Human Error: Unknown

NS -641 11/22/88 30.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Endicott Unknown Equipment Failure, Other Mechanical Failure: Other

NS -642 11/28/88 2.02 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -643 12/01/88 1.50 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -644 12/04/88 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Unknown Unknown Human Error, Overfill Human Error: Overfill

NS -645 12/05/88 4.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -646 12/05/88 10.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -647 12/05/88 1.24 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -648 12/09/88 2.38 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -649 12/19/88 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -650 12/22/88 4.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -652 12/26/88 4.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -651 12/26/88 8.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Unknown Unknown

NS -653 12/29/88 60.00 C Refined: Oil 

Drilling Mud

Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -654 01/03/89 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -655 01/08/89 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -656 01/18/89 2.38 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Unknown Unknown Unknown Unknown

NS -657 01/19/89 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -658 01/24/89 154.76 C Refined: Diesel Refined: Diesel Oil Exploration Oil Exploration Unknown Unknown Unknown Equipment Failure, Other Mechanical Failure: Other

NS -659 02/04/89 75.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other
A-12

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -660 02/05/89 11.90 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Unknown Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -661 02/06/89 1.19 D Refined: Other Refined: Other Unknown Unknown Onshore Unknown Unknown Human Error, Overfill Human Error: Overfill

NS -662 02/07/89 4.76 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Kuparuk River Unknown Human Error Human Error: Unknown

NS -663 02/10/89 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -664 02/12/89 16.67 C Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Unknown Unknown

NS -665 02/27/89 3.57 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Unknown Unknown

NS -666 03/04/89 7.14 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -667 03/07/89 2.38 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -668 03/08/89 1.43 D Refined: Diesel Refined: Diesel Unknown Unknown Onshore Unknown Unknown Human Error Human Error: Unknown

NS -669 03/10/89 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -670 03/12/89 2.38 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Unknown Unknown

NS -671 03/27/89 25.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -672 04/18/89 357.14 B Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Unknown Unknown Unknown Unknown

NS -673 04/21/89 1.50 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -674 04/22/89 4.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Unknown Unknown

NS -675 05/01/89 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -676 05/03/89 1.43 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Unknown Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -677 05/04/89 1.07 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -678 05/04/89 14.29 C Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Unknown Unknown Equipment Failure, Other Mechanical Failure: Other

NS -679 05/10/89 2.98 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -680 05/13/89 23.81 C Refined: Gasoline Refined: Other Support Facility/Services Support Facility/Services Unknown Unknown Unknown Equipment Failure, Other Mechanical Failure: Other

NS -681 05/23/89 2.62 D Refined: Hydraulic Oil Refined: Other Vehicle Support Facility/Services Unknown Unknown Unknown Human Error, Vehicle Accidents Human Error: Unknown

NS -682 05/27/89 2.00 D Refined: Oil 

Drilling Mud

Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -683 05/29/89 1.19 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -684 05/30/89 11.90 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -685 06/02/89 2.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -686 06/02/89 12.50 C Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -687 06/05/89 1.62 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -688 06/08/89 4.76 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -689 06/19/89 3.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -690 06/19/89 29.33 C Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Unknown Unknown Human Error Human Error: Unknown

NS -691 06/19/89 2.00 D Refined: Other Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -692 06/21/89 4.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -693 06/21/89 4.76 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Unknown Unknown Unknown Unknown

NS -694 06/21/89 17.10 C Refined: Other Refined: Other Unknown Unknown Unknown Unknown Unknown Unknown Unknown

NS -695 06/25/89 1.79 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -696 06/25/89 1.29 D Refined: Hydraulic Oil Refined: Other Support Facility/Services Support Facility/Services Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -697 07/02/89 1.50 D Refined: Other Refined: Other Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -698 07/03/89 2.38 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -699 07/05/89 10.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -700 07/07/89 1.79 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -701 07/08/89 2.02 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -702 07/15/89 7.14 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -703 07/17/89 7.14 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -704 07/19/89 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Milne Point Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -705 07/28/89 1.19 D Refined: Hydraulic Oil Refined: Other Support Facility/Services Support Facility/Services Onshore Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -706 07/28/89 925.00 B Crude Oil Crude Oil Oil Production Oil Production Onshore Milne Point Unknown Equipment Failure, Other Mechanical Failure: Other

NS -707 07/29/89 1.19 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Milne Point Unknown Equipment Failure, Other Mechanical Failure: Other

NS -708 08/22/89 5.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Milne Point Unknown Human Error Human Error: Unknown

NS -709 08/24/89 4.29 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -710 08/25/89 600.00 B Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Corrosion Human Error: Unknown

NS -712 08/26/89 1.19 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -711 08/26/89 2.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Unknown Unknown

NS -713 09/02/89 1.50 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -714 09/07/89 1.43 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Prudhoe Bay Unknown Human Error, Vehicle Accidents Human Error: Unknown

NS -715 09/12/89 10.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -716 09/24/89 1.67 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -717 10/09/89 25.00 C Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -718 10/11/89 2.00 D Refined: Oil 

Drilling Mud

Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown
A-13

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -719 10/16/89 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -720 11/01/89 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Endicott Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -721 11/06/89 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -722 11/08/89 265.00 B Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -723 11/18/89 2.38 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Endicott Unknown Unknown Unknown

NS -725 11/24/89 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Milne Point Unknown Human Error, Overfill Human Error: Overfill

NS -724 11/24/89 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -726 11/24/89 1.07 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -727 11/25/89 50.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Unknown Unknown Human Error Human Error: Unknown

NS -728 12/11/89 10.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -729 12/15/89 8.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -731 12/16/89 8.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -730 12/16/89 26.19 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -732 12/17/89 10.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -733 12/19/89 15.48 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -734 12/24/89 10.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -735 01/09/90 1.07 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -736 01/12/90 2.50 D Crude Oil Crude Oil Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -737 01/14/90 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -738 01/19/90 2.38 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -739 01/23/90 1.67 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -740 01/26/90 1.07 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -741 01/30/90 5.95 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Milne Point Unknown Human Error Human Error: Unknown

NS -742 02/06/90 3.57 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -743 02/07/90 1.19 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Pipe or Line Unknown Unknown

NS -744 02/11/90 1.79 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -745 02/15/90 1.31 D Refined: Hydraulic Oil Refined: Other Vehicle Support Facility/Services Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -746 02/17/90 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Milne Point Unknown Unknown Unknown

NS -747 02/19/90 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -748 02/24/90 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Milne Point Unknown Equipment Failure, Other Mechanical Failure: Other

NS -749 02/26/90 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -750 03/14/90 15.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Milne Point Unknown Equipment Failure, Other Mechanical Failure: Other

NS -751 03/26/90 1.31 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -752 03/26/90 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Milne Point Unknown Equipment Failure, Other Mechanical Failure: Other

NS -753 03/31/90 1.52 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Unknown Unknown Human Error, Overfill Human Error: Overfill

NS -754 04/05/90 2.02 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -755 04/15/90 2.86 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -756 5/1/90 3.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Tank Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -757 05/11/90 24.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Unknown Unknown Human Error Human Error: Unknown

NS -758 05/12/90 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -759 05/15/90 1.19 D Crude Oil Crude Oil Support Facility/Services Support Facility/Services Unknown Unknown Unknown Human Error Human Error: Unknown

NS -760 05/19/90 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Corrosion Human Error: Unknown

NS -761 05/20/90 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -762 05/22/90 1.19 D Refined: Other Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -763 05/23/90 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Milne Point Unknown Human Error, Overfill Human Error: Overfill

NS -764 05/31/90 1.90 D Refined: Other Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -765 06/03/90 5.71 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Unknown Unknown Unknown Unknown

NS -766 06/09/90 1.19 D Refined: Hydraulic Oil Refined: Other Support Facility/Services Support Facility/Services Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -767 6/18/90 1.30 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Onshore Prudhoe Bay Vehicle Rollover/Capsize Other

NS -768 06/22/90 1.19 D Refined: Other Refined: Other Support Facility/Services Support Facility/Services Unknown Unknown Unknown Human Error, Overfill Human Error: Overfill

NS -769 06/30/90 3.57 D Refined: Oil 

Drilling Mud

Refined: Other Support Facility/Services Support Facility/Services Onshore Unknown Unknown Equipment Failure, Other Mechanical Failure: Other

NS -770 07/03/90 5.71 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -771 07/09/90 1.31 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -772 07/11/90 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -773 07/12/90 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -774 07/18/90 6.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Milne Point Unknown Unknown Unknown

NS -775 07/20/90 1.19 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -776 7/26/90 1.50 D Crude Oil Crude Oil Oil Production Oil Production Onshore Endicott Pipe or Line Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -777 07/30/90 1.79 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Kuparuk River Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -778 08/01/90 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal
A-14

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -779 08/04/90 5.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Milne Point Unknown Unknown Unknown

NS -780 08/06/90 1.50 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Human Error Human Error: Unknown

NS -781 08/14/90 2.38 D Crude Oil Crude Oil Oil Production Oil Production Onshore Unknown Unknown Unknown Unknown

NS -782 08/15/90 9.52 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -783 09/02/90 3.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Milne Point Unknown Unknown Unknown

NS -784 09/12/90 1.50 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -785 09/22/90 30.00 C Crude Mixture Crude Oil Oil Production Oil Production Onshore Kuparuk River Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -786 09/30/90 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -787 10/01/90 1.31 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -788 10/02/90 1.31 D Refined: Hydraulic Oil Refined: Other Unknown Unknown Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -789 11/29/90 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -790 11/29/90 2.38 D Crude Oil Crude Oil Oil Production Oil Production Unknown Unknown Unknown Equipment Failure, Other Mechanical Failure: Other

NS -791 12/01/90 1.07 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Milne Point Unknown Equipment Failure, Other Mechanical Failure: Other

NS -792 12/10/90 600.00 B Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -793 12/13/90 13.81 C Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Unknown Kuparuk River Unknown Human Error Human Error: Unknown

NS -794 12/22/90 5.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -795 12/24/90 30.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -796 12/28/90 2.38 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Unknown Kuparuk River Unknown Unknown Unknown

NS -797 01/19/91 5.50 D Crude Oil Crude Oil Oil Production Oil Production Onshore Milne Point Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -798 01/21/91 3.57 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Human Error Human Error: Unknown

NS -799 02/01/91 1.19 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -800 02/04/91 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -801 02/11/91 2.02 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -802 02/20/91 19.05 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -803 02/20/91 3.67 D Refined: Hydraulic Oil Refined: Other Unknown Unknown Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -804 02/21/91 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -805 03/15/91 2.93 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Unknown Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -806 03/23/91 1.43 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -807 03/23/91 1.07 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -808 03/26/91 16.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -809 03/27/91 36.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -810 03/27/91 4.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -811 04/07/91 1.19 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Human Error, Overfill Human Error: Overfill

NS -812 04/08/91 4.76 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -813 04/11/91 1.33 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -814 04/13/91 10.60 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Unknown Unknown

NS -815 04/14/91 1.21 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Unknown Unknown Unknown Unknown

NS -816 04/19/91 4.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Milne Point Unknown Human Error Human Error: Unknown

NS -817 04/22/91 3.57 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -818 04/25/91 3.57 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Unknown Unknown Equipment Failure, Other Mechanical Failure: Other

NS -819 04/30/91 5.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -820 05/01/91 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Unknown Unknown

NS -821 05/09/91 1.50 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -822 05/13/91 2.98 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -823 05/18/91 1.19 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -824 05/19/91 4.76 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -825 05/25/91 4.76 D Refined: Diesel Refined: Diesel Unknown Unknown Onshore Unknown Unknown Human Error, Overfill Human Error: Overfill

NS -826 06/10/91 3.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -827 06/11/91 1.19 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -829 06/13/91 9.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Pipe or Line Corrosion Human Error: Unknown

NS -828 6/13/91 3.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Weld Failure Mechanical Failure: Other

NS -830 06/18/91 2.38 D Refined: Other Refined: Other Unknown Unknown Onshore Unknown Unknown Human Error Human Error: Unknown

NS -831 06/23/91 1.19 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -833 07/04/91 47.62 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Milne Point Unknown Human Error Human Error: Unknown

NS -832 07/04/91 2.38 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Milne Point Unknown Unknown Unknown

NS -834 07/12/91 2.86 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -835 07/14/91 5.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Unknown Human Error Human Error: Unknown

NS -836 07/16/91 3.57 D Refined: Other Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -837 07/16/91 2.50 D Refined: Other Refined: Other Vehicle Support Facility/Services Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -838 07/18/91 4.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -839 07/31/91 75.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other
A-15

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -840 08/01/91 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -841 08/25/91 4.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Unknown Unknown

NS -842 09/15/91 1.31 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -843 09/16/91 4.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -844 09/24/91 1.19 D Crude Oil Crude Oil Oil Production Oil Production Onshore Unknown Unknown Human Error Human Error: Unknown

NS -845 09/28/91 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -846 09/28/91 2.65 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Unknown Unknown Unknown Human Error Human Error: Unknown

NS -847 09/28/91 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -848 10/08/91 1.19 D Refined: Other Refined: Other Unknown Unknown Unknown Unknown Unknown Human Error, Overfill Human Error: Overfill

NS -849 10/08/91 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -850 11/03/91 2.62 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -851 11/19/91 2.62 D Crude Oil Crude Oil Oil Production Oil Production Unknown Endicott Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -852 11/25/91 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Corrosion Human Error: Unknown

NS -853 12/04/91 8.57 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -854 12/15/91 30.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -855 12/19/91 1.29 D Refined: Other Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -856 01/11/92 3.57 D Refined: Other Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -857 01/28/92 1.31 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -858 02/01/92 6.67 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -859 02/10/92 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -860 3/24/92 54.80 C Refined: Gasoline Refined: Other Support Facility/Services Support Facility/Services Onshore Support Services Vehicle Rollover/Capsize Other

NS -861 04/14/92 6.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -862 04/20/92 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -863 05/26/92 4.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -864 05/31/92 5.95 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -865 06/07/92 5.95 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -866 06/24/92 10.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -867 07/11/92 2.02 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -868 7/15/92 2.90 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Well Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -869 07/30/92 1.07 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Human Error Human Error: Unknown

NS -870 08/21/92 2.38 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -871 8/28/92 8.30 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Well Human Error Human Error: Unknown

NS -872 08/29/92 8.10 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -873 09/11/92 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -874 09/17/92 8.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Pipe or Line Human Error Human Error: Unknown

NS -875 9/26/92 57.10 C Refined: Unknown Refined: Other Vehicle Support Facility/Services Onshore Prudhoe Bay Vehicle Rollover/Capsize Other

NS -876 10/07/92 1.31 D Refined: Hydraulic Oil Refined: Other Unknown Unknown Unknown Prudhoe Bay Unknown Unknown Unknown

NS -877 12/11/92 3.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -878 02/10/93 1.50 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -879 02/21/93 5.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Unknown Unknown

NS -880 03/07/93 1.31 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -881 03/31/93 1.31 D Refined: Hydraulic Oil Refined: Other Unknown Unknown Unknown Unknown Unknown Human Error Human Error: Unknown

NS -882 04/03/93 1.19 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -883 04/05/93 4.88 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Unknown Unknown Human Error Human Error: Unknown

NS -884 04/19/93 11.90 C Refined: Diesel Refined: Diesel Unknown Unknown Unknown Prudhoe Bay Unknown Unknown Unknown

NS -885 04/23/93 19.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Unknown Unknown Human Error Human Error: Unknown

NS -886 04/25/93 1.07 D Refined: Hydraulic Oil Refined: Other Unknown Unknown Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -887 06/07/93 40.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -888 06/10/93 300.00 B Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -889 06/12/93 10.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -890 6/15/93 1.20 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Unknown Unknown

NS -891 06/17/93 50.00 C Refined: Diesel Refined: Diesel Unknown Unknown Onshore Prudhoe Bay Unknown Unknown Unknown

NS -892 06/19/93 3.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Unknown Unknown Unknown

NS -893 06/21/93 15.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -894 07/09/93 7.14 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Unknown Unknown

NS -895 07/10/93 1.19 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Human Error Human Error: Unknown

NS -896 08/17/93 675.00 B Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Corrosion Human Error: Unknown

NS -897 08/30/93 200.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -898 09/03/93 30.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -899 09/05/93 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -900 9/20/93 4.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Tank Human Error, Overfill Human Error: Overfill
A-16

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -901 09/20/93 168.00 C Crude Mixture Crude Oil Oil Production Oil Production Onshore Kuparuk River Unknown Human Error Human Error: Unknown

NS -902 09/26/93 650.12 B Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -903 10/01/93 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Human Error Human Error: Unknown

NS -904 11/13/93 100.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -905 12/14/93 30.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Unknown Unknown

NS -906 12/20/93 1.19 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -907 12/24/93 200.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -908 12/30/93 400.00 B Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -909 01/01/94 5.95 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -910 02/07/94 5.95 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Human Error Human Error: Unknown

NS -911 02/16/94 32.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Milne Point Unknown Equipment Failure, Other Mechanical Failure: Other

NS -912 02/22/94 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -913 02/27/94 2.14 D Refined: Hydraulic Oil Refined: Other Unknown Unknown Unknown Prudhoe Bay Unknown Unknown Unknown

NS -914 03/18/94 1.19 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Human Error Human Error: Unknown

NS -915 04/03/94 1.19 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -916 04/06/94 3.10 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -917 05/03/94 2.38 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -919 05/10/94 142.86 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -918 5/10/94 2.40 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Coiled Tubing Unit Fire/Explosion Other

NS -920 05/18/94 3.50 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Human Error Human Error: Unknown

NS -921 06/22/94 6.71 D Refined: Other Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -922 07/10/94 1.90 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Unknown Unknown

NS -923 07/18/94 10.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -924 07/23/94 1.19 D Refined: Other Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -925 08/02/94 3.57 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -926 09/26/94 1.90 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -927 10/31/94 183.14 C Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Corrosion Human Error: Unknown

NS -928 11/06/94 40.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Unknown Unknown

NS -929 11/06/94 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -930 11/21/94 4.80 D Crude Oil Crude Oil Oil Production Oil Production Onshore Unknown Other Human Error, Overfill Human Error: Overfill

NS -931 12/02/94 2.02 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -933 12/05/94 1.33 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -934 12/05/94 50.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Unknown Unknown Equipment Failure, Other Mechanical Failure: Other

NS -932 12/5/94 1.20 D Crude Oil Crude Oil Oil Production Oil Production Onshore Unknown Well Other Other

NS -935 01/01/95 11.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -936 01/02/95 11.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -937 01/07/95 17.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Equipment Failure, Other Mechanical Failure: Other

NS -938 01/16/95 4.76 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Unknown Unknown

NS -939 02/03/95 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -940 02/05/95 8.33 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -941 02/13/95 5.95 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Unknown Unknown Unknown Unknown Unknown

NS -942 3/10/95 71.40 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Line Failure Mechanical Failure: Other

NS -943 04/04/95 2.38 D Refined: Hydraulic Oil Refined: Other Vehicle Support Facility/Services Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -944 5/1/95 2.40 D Refined: Unknown Refined: Other Oil Production Oil Production Onshore Endicott Vehicle Dumping Human Error: Other

NS -945 05/01/95 4.88 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -946 05/07/95 5.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -947 06/03/95 2.62 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -948 06/07/95 2.38 D Refined: Hydraulic Oil Refined: Other Unknown Unknown Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -949 7/5/95 1.30 D Refined: Aviation Refined: Other Air Transportation Support Facility/Services Onshore Kuparuk River Unknown Unknown Unknown

NS -950 7/11/95 2.40 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Onshore Unknown Unknown Unknown Unknown

NS -951 07/14/95 2.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Milne Point Unknown Unknown Unknown

NS -952 7/26/95 7.10 D Refined: Diesel Refined: Diesel Unknown Unknown Onshore Prudhoe Bay Unknown Unknown Unknown

NS -953 07/28/95 20.00 C Refined: Other Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Unknown Unknown Unknown

NS -954 07/29/95 10.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -955 08/06/95 6.00 D Crude Oil Crude Oil Unknown Unknown Onshore Kuparuk River Unknown Unknown Unknown

NS -956 08/13/95 7.14 D Refined: Diesel Refined: Diesel Unknown Unknown Onshore Unknown Unknown Unknown Unknown

NS -957 08/15/95 25.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Unknown Unknown

NS -958 10/05/95 50.00 C Refined: Oil 

Drilling Mud

Refined: Other Unknown Unknown Onshore Unknown Unknown Equipment Failure, Other Mechanical Failure: Other

NS -959 10/23/95 1.28 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Equipment Failure, Other Mechanical Failure: Other

NS -960 10/28/95 1.20 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Onshore Prudhoe Bay Unknown Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal
A-17

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -961 11/26/95 10.00 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Onshore Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -962 12/18/95 1.62 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -963 12/22/95 2.57 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -964 1/2/96 1.20 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Pipe or Line Equipment Failure, Line Failure Mechanical Failure: Other

NS -965 01/07/96 42.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -966 1/8/96 1.40 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Milne Point Unknown Equipment Failure, Gauge/Site Glass Failure Mechanical Failure: Other

NS -968 01/27/96 8.33 D Refined: Other Refined: Other Oil Production Oil Production Unknown Endicott Unknown Equipment Failure, Other Mechanical Failure: Other

NS -967 1/27/96 8.30 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Unknown Mechanical Failure: Unknow

NS -969 01/31/96 7.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Milne Point Unknown Equipment Failure, Other Mechanical Failure: Other

NS -970 2/6/96 10.70 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Human Error Human Error: Unknown

NS -971 2/11/96 1.90 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -972 2/20/96 1.80 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Milne Point Tank Human Error, Overfill Human Error: Overfill

NS -973 02/25/96 4.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -974 02/29/96 1.38 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -975 03/01/96 2.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Unknown Unknown

NS -976 3/10/96 7.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Unknown Unknown Unknown

NS -977 03/28/96 200.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Unknown Unknown

NS -978 4/7/96 7.10 D Refined: Diesel Refined: Diesel Oil Production Oil Production Offshore Prudhoe Bay Unknown External Factors Other

NS -979 4/17/96 25.60 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Freezing Mechanical Failure: Other

NS -981 4/24/96 3.30 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Freezing Mechanical Failure: Other

NS -982 05/26/96 7.00 D Crude Oil Crude Oil Vehicle Support Facility/Services Unknown Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -983 06/01/96 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Unknown Unknown Unknown Unknown

NS -984 6/2/96 1.20 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Unknown Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -985 6/7/96 1.40 D Refined: Hydraulic Oil Refined: Other Vehicle Support Facility/Services Onshore Prudhoe Bay Pipe or Line Equipment Failure, Line Failure Mechanical Failure: Other

NS -986 6/8/96 5.00 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Onshore Prudhoe Bay Unknown Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -987 6/13/96 1.20 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Unknown Unknown Unknown

NS -988 6/13/96 1.10 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Unknown Unknown Unknown

NS -989 6/17/96 1.10 D Refined: Hydraulic Oil Refined: Other Vehicle Support Facility/Services Onshore Kuparuk River Pipe or Line Equipment Failure, Line Failure Mechanical Failure: Other

NS -990 6/30/96 26.20 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Puncture Human Error: Other

NS -991 7/1/96 1.70 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Onshore Prudhoe Bay Unknown Unknown Unknown

NS -992 07/06/96 3.00 D Crude Mixture Crude Oil Unknown Unknown Onshore Kuparuk River Unknown Corrosion Human Error: Unknown

NS -993 07/09/96 10.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Pipe or Line Unknown Unknown

NS -994 07/25/96 9.52 D Crude Oil Crude Oil Oil Production Oil Production Onshore Endicott Unknown Human Error Human Error: Unknown

NS -995 08/05/96 1.19 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -996 8/13/96 1.20 D Refined: Diesel Refined: Diesel Unknown Unknown Onshore Unknown Unknown Hull Failure Mechanical Failure: Other

NS -997 8/13/96 16.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -998 8/16/96 2.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Human Error Human Error: Unknown

NS -999 8/18/96 14.30 C Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Line Failure Mechanical Failure: Other

NS -1000 8/21/96 2.90 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Human Error Human Error: Unknown

NS -1001 09/09/96 2.38 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -1002 09/11/96 1.19 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -1003 9/13/96 1.70 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Erosion Mechanical Failure: Other

NS -1004 09/27/96 4.88 D Refined: Diesel Refined: Diesel Unknown Unknown Onshore Unknown Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1005 10/17/96 1.10 D Crude Oil Crude Oil Oil Production Oil Production Onshore Milne Point Pipe or Line Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1006 10/18/96 1.20 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Line Failure Mechanical Failure: Other

NS -1007 10/26/96 2.00 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Onshore Milne Point Unknown Collision/Allision Human Error: Other

NS -1008 11/22/96 7.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Weld Failure Mechanical Failure: Other

NS -1009 12/20/96 1.70 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Weld Failure Mechanical Failure: Other

NS -1010 1/16/97 1.30 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Drum(s) Human Error Human Error: Unknown

NS -1011 1/23/97 2.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Erosion Mechanical Failure: Other

NS -1012 2/3/97 1.20 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Human Error Human Error: Unknown

NS -1013 02/04/97 50.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Unknown Unknown Human Error Human Error: Unknown

NS -1014 2/5/97 1.40 D Refined: Hydraulic Oil Refined: Other Vehicle Support Facility/Services Onshore Kuparuk River Pipe or Line Equipment Failure, Line Failure Mechanical Failure: Other

NS -1015 2/7/97 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -1016 2/13/97 2.10 D Refined: Hydraulic Oil Refined: Other Vehicle Support Facility/Services Onshore Kuparuk River Pipe or Line Equipment Failure, Line Failure Mechanical Failure: Other

NS -1017 2/18/97 2.10 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Heavy Equipment Equipment Failure, Line Failure Mechanical Failure: Other

NS -1018 02/28/97 2.00 D Refined: Other Refined: Other Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1019 3/8/97 5.20 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1020 3/12/97 10.00 D Crude Oil Crude Oil Oil Production Oil Production Offshore Endicott Pipe or Line Freezing Mechanical Failure: Other

NS -1021 3/12/97 10.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1022 3/17/97 2.40 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Prudhoe Bay Tank External Factors Other
A-18

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -1023 03/26/97 117.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1024 3/31/97 10.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1025 04/04/97 30.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Unknown Human Error Human Error: Unknown

NS -1026 04/15/97 10.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -1027 04/27/97 1.79 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Kuparuk River Unknown Unknown Unknown

NS -1028 4/30/97 41.20 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Weld Failure Mechanical Failure: Other

NS -1029 5/3/97 2.30 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Weld Failure Mechanical Failure: Other

NS -1030 5/19/97 180.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Unknown Unknown

NS -1031 5/20/97 1.70 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Weld Failure Mechanical Failure: Other

NS -1032 06/04/97 4.76 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1033 6/5/97 7.10 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Well Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1034 6/12/97 4.80 D Refined: Diesel Refined: Diesel Oil Exploration Oil Exploration Onshore Exploration Drum(s) Corrosion Mechanical Failure: Corrosion

NS -1035 6/12/97 11.90 C Refined: Diesel Refined: Diesel Oil Exploration Oil Exploration Onshore Exploration Drum(s) Corrosion Mechanical Failure: Corrosion

NS -1036 6/22/97 11.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Milne Point Well Weld Failure Mechanical Failure: Other

NS -1038 06/22/97 5.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Milne Point Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1037 6/22/97 47.60 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Milne Point Heavy Equipment Rollover/Capsize Other

NS -1039 06/25/97 1.33 D Refined: Diesel Refined: Diesel Unknown Unknown Onshore Unknown Unknown Unknown Unknown

NS -1040 7/2/97 3.70 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Puncture Human Error: Other

NS -1041 7/3/97 1.40 D Refined: Hydraulic Oil Refined: Other Vehicle Support Facility/Services Onshore Prudhoe Bay Unknown Unknown Unknown

NS -1042 7/5/97 3.00 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Unknown Unknown Unknown

NS -1043 7/15/97 47.60 C Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Corrosion Mechanical Failure: Corrosion

NS -1044 7/21/97 24.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1045 7/21/97 1.20 D Refined: Diesel Refined: Diesel Air Transportation Support Facility/Services Onshore Support Services Tank Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1046 7/28/97 1.20 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Unknown Unknown Unknown Unknown

NS -1047 7/29/97 1.40 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Milne Point Unknown Unknown Unknown

NS -1048 8/3/97 2.50 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -1049 08/04/97 10.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1051 09/12/97 20.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Human Error Human Error: Unknown

NS -1050 9/12/97 3.60 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1052 09/15/97 6.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Corrosion Human Error: Unknown

NS -1053 9/27/97 1.20 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Onshore Kuparuk River Vehicle Rollover/Capsize Other

NS -1054 10/13/97 4.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Over Pressure Mechanical Failure: Overpressure

NS -1055 10/14/97 2.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1056 10/26/97 15.70 C Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Unknown Unknown Unknown

NS -1057 11/11/97 124.20 C Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Onshore Support Services Tank Collision/Allision Human Error: Other

NS -1058 12/8/97 3.20 D Refined: Aviation Refined: Other Vehicle Support Facility/Services Onshore Badami Vehicle Cargo Not Secured Human Error: Other

NS -1059 12/14/97 2.90 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1060 12/21/97 3.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Human Error Human Error: Unknown

NS -1061 01/02/98 1.19 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Over Pressure Mechanical Failure: Overpressure

NS -1062 01/10/98 300.00 B Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Unknown Unknown Unknown

NS -1063 1/15/98 1.50 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1064 1/26/98 3.60 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Human Error Human Error: Unknown

NS -1065 1/27/98 28.60 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1066 1/31/98 1.40 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Human Error Human Error: Unknown

NS -1067 3/3/98 4.90 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Weld Failure Mechanical Failure: Other

NS -1068 03/18/98 5.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Over Pressure Mechanical Failure: Overpressure

NS -1069 03/21/98 6.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Pipe or Line Equipment Failure, Other Mechanical Failure: Other

NS -1070 3/23/98 11.90 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Human Error Human Error: Unknown

NS -1071 3/25/98 14.30 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Corrosion Mechanical Failure: Corrosion

NS -1072 4/7/98 4.80 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Unknown Unknown Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1073 4/8/98 2.60 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Human Error Human Error: Unknown

NS -1074 04/13/98 10.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1075 4/15/98 1.50 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Onshore Colville River, AlpineHeavy Equipment Rollover/Capsize Other

NS -1076 04/23/98 3.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -1077 05/01/98 3.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Unknown Unknown

NS -1078 05/02/98 2.88 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1079 05/17/98 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -1080 05/29/98 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -1081 06/03/98 1.19 D Crude Oil Crude Oil Oil Production Oil Production Onshore Milne Point Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1082 06/12/98 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -1083 06/16/98 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Unknown Mechanical Failure: Unknow
A-19

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -1084 7/19/98 4.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Milne Point Pipe or Line Corrosion Mechanical Failure: Corrosion

NS -1085 8/2/98 1.40 D Refined: Diesel Refined: Diesel Oil Production Oil Production Offshore Prudhoe Bay Coiled Tubing Unit Unknown Unknown

NS -1086 8/3/98 6.00 D Refined: Diesel Refined: Diesel Unknown Unknown Onshore Unknown Unknown Unknown Unknown

NS -1087 8/21/98 23.80 C Crude Oil Crude Oil Oil Production Oil Production Offshore Endicott Pipe or Line Weld Failure Mechanical Failure: Other

NS -1088 08/24/98 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Corrosion Human Error: Unknown

NS -1089 09/25/98 2.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Milne Point Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1090 10/3/98 4.60 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1092 10/06/98 2.38 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -1091 10/6/98 2.50 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Corrosion Mechanical Failure: Corrosion

NS -1093 10/23/98 3.60 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Onshore Kuparuk River Tank Human Error, Overfill Human Error: Overfill

NS -1094 10/30/98 6.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Over Pressure Mechanical Failure: Overpressure

NS -1095 12/09/98 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1096 12/24/98 4.80 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Tank Human Error, Overfill Human Error: Overfill

NS -1097 01/28/99 1.43 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1098 2/6/99 1.20 D Refined: Diesel Refined: Diesel Bulk Fuel Terminal Support Facility/Services Onshore Unknown Unknown Human Error Human Error: Unknown

NS -1100 03/12/99 2.45 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Unknown Endicott Unknown Unknown Unknown

NS -1101 04/07/99 260.00 B Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -1102 4/9/99 2.40 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -1103 04/18/99 1.43 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Pipe or Line Equipment Failure, Other Mechanical Failure: Other

NS -1104 05/01/99 1.31 D Crude Oil Crude Oil Oil Production Oil Production Unknown Badami Unknown Human Error, Overfill Human Error: Overfill

NS -1105 5/4/99 6.00 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Onshore Colville River, AlpineUnknown Rollover/Capsize Other

NS -1106 5/19/99 47.60 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Well Unknown Unknown

NS -1107 06/01/99 1.43 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Unknown Endicott Unknown Unknown Unknown

NS -1108 6/6/99 4.80 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Endicott Tank Human Error, Overfill Human Error: Overfill

NS -1109 6/10/99 30.40 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Corrosion Mechanical Failure: Corrosion

NS -1110 6/15/99 4.50 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Support Services Tank Equipment Failure, Line Failure Mechanical Failure: Other

NS -1111 06/17/99 4.76 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Endicott Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1112 6/22/99 1.80 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Container, Other Human Error, Overfill Human Error: Overfill

NS -1113 7/3/99 4.80 D Refined: Hydraulic Oil Refined: Other Unknown Unknown Onshore Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1114 07/10/99 1.64 D Refined: Other Refined: Other Oil Production Oil Production Unknown Kuparuk River Unknown Unknown Unknown

NS -1115 07/17/99 100.00 C Refined: Other Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -1116 07/23/99 30.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Unknown Corrosion Human Error: Unknown

NS -1117 07/23/99 1.19 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1118 08/12/99 2.62 D Crude Oil Crude Oil Oil Production Oil Production Unknown Endicott Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1119 08/15/99 32.14 C Crude Mixture Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1120 9/6/99 1.50 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Unknown Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1121 09/07/99 1.43 D Refined: Other Refined: Other Unknown Unknown Unknown Unknown Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1122 09/15/99 1.79 D Crude Oil Crude Oil Oil Production Oil Production Unknown Endicott Unknown Unknown Unknown

NS -1123 10/4/99 6.20 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Unknown Unknown Unknown

NS -1124 10/10/99 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1125 11/10/99 3.57 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1126 11/11/99 2.38 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1127 11/22/99 5.10 D Refined: Diesel Refined: Diesel Transmission Pipeline Oil Production Onshore Kuparuk River Pipe or Line Unknown Unknown

NS -1128 12/16/99 40.47 C Crude Oil Crude Oil Oil Production Oil Production Unknown Unknown Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1129 12/22/99 4.40 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Unknown Endicott Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1130 12/23/99 9.05 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Unknown Unknown Unknown Unknown

NS -1131 01/25/00 13.09 C Crude Oil Crude Oil Oil Production Oil Production Unknown Endicott Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1132 1/27/00 1.80 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -1133 2/6/00 1.40 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Well Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1134 2/14/00 4.80 D Crude Oil Crude Oil Oil Production Oil Production Onshore Badami Pipe or Line Corrosion Mechanical Failure: Corrosion

NS -1135 02/14/00 1.07 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Equipment Failure, Other Mechanical Failure: Other

NS -1136 02/16/00 2.98 D Crude Oil Crude Oil Oil Production Oil Production Unknown Badami Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1137 02/17/00 4.05 D Crude Oil Crude Oil Oil Production Oil Production Unknown Endicott Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1138 03/02/00 142.86 C Refined: Other Refined: Other Unknown Unknown Unknown Unknown Unknown Unknown Unknown

NS -1139 03/13/00 4.77 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1140 3/15/00 1.20 D Refined: Hydraulic Oil Refined: Other Vehicle Support Facility/Services Onshore Prudhoe Bay Pipe or Line Equipment Failure, Line Failure Mechanical Failure: Other

NS -1141 3/20/00 23.80 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Weld Failure Mechanical Failure: Other

NS -1142 4/24/00 11.90 C Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Colville River, AlpineDrum(s) Cargo Not Secured Human Error: Other

NS -1143 5/1/00 4.80 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Well Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1144 05/05/00 1.14 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Human Error, Overfill Human Error: Overfill

NS -1145 5/6/00 4.80 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal
A-20

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -1146 05/19/00 2.62 D Refined: Other Refined: Other Vehicle Support Facility/Services Unknown Kuparuk River Unknown Human Error Human Error: Unknown

NS -1147 6/8/00 2.40 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Weld Failure Mechanical Failure: Other

NS -1148 6/19/00 1.20 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Weld Failure Mechanical Failure: Other

NS -1149 6/19/00 1.70 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -1150 6/27/00 2.40 D Crude Oil Crude Oil Oil Production Oil Production Onshore Milne Point Pipe or Line Erosion Mechanical Failure: Other

NS -1151 06/27/00 4.76 D Refined: Other Refined: Other Unknown Unknown Onshore Unknown Unknown Unknown Unknown

NS -1152 07/01/00 3.57 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1153 07/07/00 4.17 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Unknown Endicott Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1154 7/12/00 15.50 C Refined: Lube/Gear Oil Refined: Other Transmission Pipeline Oil Production Onshore Prudhoe Bay Pipe or Line Corrosion Mechanical Failure: Corrosion

NS -1155 07/12/00 2.02 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1156 07/17/00 3.57 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1157 08/07/00 12.57 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1158 08/14/00 3.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -1159 8/20/00 2.60 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Weld Failure Mechanical Failure: Other

NS -1160 08/21/00 715.00 B Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1161 9/1/00 2.10 D Refined: Unknown Refined: Other Unknown Unknown Onshore Kuparuk River Unknown Unknown Unknown

NS -1162 09/06/00 1.19 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1163 9/13/00 1.70 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Onshore Prudhoe Bay Vehicle Cargo Not Secured Human Error: Other

NS -1164 09/16/00 1.90 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Corrosion Human Error: Unknown

NS -1166 09/26/00 2.38 D Refined: Other Refined: Other Unknown Unknown Unknown Endicott Unknown Human Error Human Error: Unknown

NS -1165 9/26/00 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Unknown Unknown

NS -1167 10/19/00 10.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1168 12/1/00 15.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Freezing Mechanical Failure: Other

NS -1169 12/1/00 2.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1170 12/2/00 2.70 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1171 12/04/00 15.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -1172 12/9/00 2.60 D Refined: Lube/Gear Oil Refined: Other Support Facility/Services Support Facility/Services Onshore Kuparuk River Drum(s) Unknown Unknown

NS -1173 12/17/00 180.95 C Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1174 12/24/00 1.10 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Colville River, AlpineDrum(s) Puncture Human Error: Other

NS -1175 12/24/00 36.00 C Refined: Diesel Refined: Diesel Bulk Fuel Terminal Support Facility/Services Onshore Prudhoe Bay Tank Human Error, Overfill Human Error: Overfill

NS -1176 12/27/00 1.70 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Corrosion Mechanical Failure: Corrosion

NS -1177 1/5/01 5.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Colville River, AlpineUnknown Unknown Unknown

NS -1178 1/12/01 2.40 D Refined: Diesel Refined: Diesel Bulk Fuel Terminal Support Facility/Services Onshore Prudhoe Bay Tank Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -1179 1/15/01 1.90 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Unknown Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -1180 1/21/01 1.10 D Refined: Lube/Gear Oil Refined: Other Vehicle Support Facility/Services Onshore Prudhoe Bay Heavy Equipment Equipment Failure, Gauge/Site Glass Failure Mechanical Failure: Other

NS -1181 1/22/01 68.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Well Human Error Human Error: Unknown

NS -1182 02/02/01 24.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -1183 02/14/01 1.79 D Refined: Other Refined: Other Vehicle Support Facility/Services Unknown Colville River, AlpineUnknown Equipment Failure, Other Mechanical Failure: Other

NS -1184 02/19/01 607.14 B Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Over Pressure Mechanical Failure: Overpressure

NS -1185 02/19/01 8.21 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1187 3/6/01 1.50 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Onshore Prudhoe Bay Vehicle Cargo Not Secured Human Error: Other

NS -1188 03/09/01 2.62 D Refined: Other Refined: Other Oil Production Oil Production Unknown North Star Unknown Human Error Human Error: Unknown

NS -1189 3/12/01 2.40 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Onshore Unknown Unknown Collision/Allision Human Error: Other

NS -1190 3/20/01 3.00 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Milne Point Unknown Human Error Human Error: Unknown

NS -1191 3/29/01 3.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Colville River, AlpineTank Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -1192 3/31/01 1.20 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Unknown External Factors Other

NS -1193 04/01/01 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -1194 4/3/01 1.80 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Onshore Prudhoe Bay Tank Human Error, Overfill Human Error: Overfill

NS -1196 04/15/01 23.80 C Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Corrosion Human Error: Unknown

NS -1195 4/15/01 3.50 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Corrosion Mechanical Failure: Corrosion

NS -1197 4/23/01 1.80 D Crude Oil Crude Oil Oil Production Oil Production Offshore Endicott Pipe or Line Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1198 4/23/01 15.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1199 5/4/01 3.60 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore North Star Unknown Unknown Unknown

NS -1200 05/10/01 9.52 D Refined: Other Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1201 5/11/01 9.50 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1202 5/20/01 3.60 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Vehicle Cargo Not Secured Human Error: Other

NS -1203 05/27/01 2.50 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1204 06/07/01 1.19 D Crude Oil Crude Oil Oil Exploration Oil Exploration Unknown Unknown Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1205 06/07/01 11.90 C Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1206 6/11/01 1.20 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1207 06/14/01 1.19 D Refined: Other Refined: Other Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other
A-21

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -1208 06/25/01 1.19 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -1209 07/04/01 1.19 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1210 7/7/01 3.80 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Corrosion Mechanical Failure: Corrosion

NS -1211 07/16/01 1.19 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1212 7/21/01 10.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Corrosion Mechanical Failure: Corrosion

NS -1213 7/25/01 1.30 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Container, Other Puncture Human Error: Other

NS -1214 08/10/01 1.43 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1215 08/18/01 1.43 D Refined: Other Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1216 9/6/01 4.00 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Other Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1217 9/15/01 35.70 C Refined: Unknown Refined: Other Support Facility/Services Support Facility/Services Onshore Support Services Unknown Unknown Unknown

NS -1218 9/25/01 14.30 C Refined: Aviation Refined: Other Air Transportation Support Facility/Services Onshore Colville River, AlpineTank Collision/Allision Human Error: Other

NS -1219 10/3/01 1.50 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Tank Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -1220 10/27/01 1.10 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Heavy Equipment Equipment Failure, Gauge/Site Glass Failure Mechanical Failure: Other

NS -1221 11/15/01 2.00 D Crude Oil Crude Oil Oil Production Oil Production Offshore North Star Pipe or Line Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1222 11/20/01 1.19 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Human Error Human Error: Unknown

NS -1223 11/22/01 1.43 D Crude Oil Crude Oil Oil Production Oil Production Onshore Milne Point Unknown Human Error, Overfill Human Error: Overfill

NS -1224 11/24/01 1.90 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Human Error Human Error: Unknown

NS -1225 11/28/01 7.10 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Line Failure Mechanical Failure: Other

NS -1226 11/30/01 2.70 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Erosion Mechanical Failure: Other

NS -1227 12/3/01 10.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Colville River, AlpineTank Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1228 12/13/01 1.71 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1229 12/15/01 2.40 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1230 12/15/01 61.90 C Crude Oil Crude Oil Oil Production Oil Production Unknown Unknown Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1231 01/02/02 1.31 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown North Star Unknown Human Error Human Error: Unknown

NS -1232 1/3/02 1.30 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Offshore North Star Drum(s) Collision/Allision Human Error: Other

NS -1233 1/3/02 1.30 D Refined: Diesel Refined: Diesel Oil Production Oil Production Offshore North Star Other Unknown Unknown

NS -1234 01/09/02 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1235 1/14/02 2.70 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Well Erosion Mechanical Failure: Other

NS -1236 2/1/02 2.40 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Other Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1237 2/23/02 3.50 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Tank Human Error, Overfill Human Error: Overfill

NS -1238 3/1/02 1.20 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore North Star Heavy Equipment Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1239 3/11/02 1.20 D Refined: Hydraulic Oil Refined: Other Oil Exploration Oil Exploration Onshore Exploration Heavy Equipment Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1240 4/7/02 2.30 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Erosion Mechanical Failure: Other

NS -1241 4/15/02 1.20 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Unknown Unknown Unknown

NS -1242 5/6/02 2.40 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Tank Weld Failure Mechanical Failure: Other

NS -1243 5/6/02 2.40 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Other Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1244 5/11/02 1.50 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Colville River, AlpineTank Human Error Human Error: Unknown

NS -1245 05/29/02 21.28 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1246 6/11/02 1.70 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1247 7/10/02 1.20 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Heavy Equipment Equipment Failure, Line Failure Mechanical Failure: Other

NS -1248 7/14/02 11.30 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Erosion Mechanical Failure: Other

NS -1249 7/16/02 8.30 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Hydraulic SystemEquipment Failure, Gauge/Site Glass Failure Mechanical Failure: Other

NS -1250 07/18/02 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Unknown Pipe or Line Unknown Unknown

NS -1251 08/01/02 30.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1252 8/6/02 17.90 C Crude Oil Crude Oil Oil Production Oil Production Onshore Milne Point Pipe or Line Weld Failure Mechanical Failure: Other

NS -1253 8/12/02 1.80 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1254 8/29/02 23.80 C Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Onshore Kuparuk River Tank Rollover/Capsize Other

NS -1255 9/8/02 2.40 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Support Services Tank Equipment Failure, Gauge/Site Glass Failure Mechanical Failure: Other

NS -1256 9/14/02 1.30 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Other Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -1258 10/07/02 1.50 D Refined: Other Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1257 10/7/02 6.50 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Well Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1259 10/16/02 23.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Human Error Human Error: Unknown

NS -1260 11/4/02 7.10 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Corrosion Mechanical Failure: Corrosion

NS -1261 11/5/02 1.20 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Heavy Equipment Human Error, Overfill Human Error: Overfill

NS -1262 11/16/02 2.00 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Well Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1263 11/25/02 1.80 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Tank Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -1264 12/17/02 6.55 D Refined: Other Refined: Other Oil Production Oil Production Unknown Kuparuk River Unknown Human Error, Overfill Human Error: Overfill

NS -1265 12/24/02 1.90 D Crude Oil Crude Oil Oil Production Oil Production Onshore Badami Pipe or Line Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1266 01/20/03 1.91 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1267 2/28/03 85.10 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Fuel Pump Crack Mechanical Failure: Other

NS -1268 3/9/03 2.00 D Refined: Hydraulic Oil Refined: Other Oil Exploration Oil Exploration Offshore Exploration Pipe or Line Equipment Failure, Line Failure Mechanical Failure: Other
A-22

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -1269 3/11/03 2.10 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Onshore Prudhoe Bay Tank Rollover/Capsize Other

NS -1270 3/14/03 109.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Badami Well Miss-Injection Human Error: Other

NS -1272 03/22/03 2.38 D Crude Mixture Crude Oil Oil Production Oil Production Unknown Unknown Unknown Human Error, Overfill Human Error: Overfill

NS -1273 03/30/03 2.38 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Human Error Human Error: Unknown

NS -1274 4/13/03 2.60 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1275 4/24/03 2.40 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Well Equipment Failure, Line Failure Mechanical Failure: Other

NS -1276 4/25/03 4.50 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Prudhoe Bay Tank Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1277 05/11/03 1.47 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1278 5/17/03 1.80 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Heavy Equipment Rollover/Capsize Other

NS -1279 05/25/03 8.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Corrosion Human Error: Unknown

NS -1280 5/27/03 142.90 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Corrosion Mechanical Failure: Corrosion

NS -1281 6/13/03 3.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Well Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1282 6/24/03 4.50 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Support Services Tank Equipment Failure, Gauge/Site Glass Failure Mechanical Failure: Other

NS -1283 6/29/03 1.40 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Tank Equipment Failure, Line Failure Mechanical Failure: Other

NS -1285 7/18/03 4.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Milne Point Well Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1286 7/20/03 4.80 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1287 7/25/03 2.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Weld Failure Mechanical Failure: Other

NS -1288 8/8/03 3.30 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Colville River, AlpineContainer, Other Human Error Human Error: Unknown

NS -1289 8/12/03 1.20 D Refined: Hydraulic Oil Refined: Other Vehicle Support Facility/Services Onshore Support Services Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1290 8/21/03 1.30 D Refined: Lube/Gear Oil Refined: Other Support Facility/Services Support Facility/Services Onshore Support Services Drum(s) Crack Mechanical Failure: Other

NS -1291 09/11/03 1.19 D Refined: Other Refined: Other Unknown Unknown Unknown Unknown Unknown Unknown Unknown

NS -1292 9/12/03 1.20 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Other Mechanical Failure: Other

NS -1293 9/24/03 46.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore North Star Other Unknown Unknown

NS -1294 10/7/03 5.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Badami Well Miss-Injection Human Error: Other

NS -1295 11/1/03 3.80 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Badami Other Equipment Failure, Gauge/Site Glass Failure Mechanical Failure: Other

NS -1296 11/3/03 2.10 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Milne Point Tank Human Error, Overfill Human Error: Overfill

NS -1297 11/17/03 261.90 B Refined: Diesel Refined: Diesel Bulk Fuel Terminal Support Facility/Services Onshore Prudhoe Bay Tank Human Error Human Error: Unknown

NS -1298 11/18/03 1.20 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Offshore North Star Tank Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1299 12/06/03 23.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Milne Point Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1300 12/31/03 3.10 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Milne Point Well Equipment Failure, Line Failure Mechanical Failure: Other

NS -1301 01/13/04 2.38 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1302 01/14/04 2.86 D Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1303 1/16/04 1.80 D Refined: Diesel Refined: Diesel Oil Exploration Oil Exploration Onshore Exploration Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1304 2/28/04 38.10 C Refined: Naphtha Refined: Other Oil Production Oil Production Onshore Kuparuk River Other Equipment Failure, Line Failure Mechanical Failure: Other

NS -1305 3/17/04 23.80 C Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Weld Failure Mechanical Failure: Other

NS -1306 3/18/04 10.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Colville River, AlpinePipe or Line Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1307 3/26/04 1.60 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Colville River, AlpinePipe or Line Human Error, Overfill Human Error: Overfill

NS -1308 4/5/04 2.90 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Tank Human Error, Overfill Human Error: Overfill

NS -1309 5/9/04 5.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Unknown Unknown

NS -1310 5/12/04 18.20 C Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Freezing Mechanical Failure: Other

NS -1311 05/26/04 1.43 D Refined: Other Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Corrosion Human Error: Unknown

NS -1312 5/30/04 2.00 D Refined: Diesel Refined: Diesel Oil Exploration Oil Exploration Onshore Exploration Well Unknown Unknown

NS -1313 06/08/04 1.19 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -1314 06/18/04 135.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1315 06/23/04 1.19 D Refined: Other Refined: Other Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1316 6/24/04 1.90 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Well Weld Failure Mechanical Failure: Other

NS -1317 7/10/04 3.10 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Other Human Error, Overfill Human Error: Overfill

NS -1318 07/14/04 1.10 D Refined: Other Refined: Other Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1319 07/15/04 1.20 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1320 7/19/04 2.90 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Well Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1321 7/30/04 2.40 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Unknown Unknown Unknown

NS -1322 9/20/04 1.80 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Hydraulic SystemEquipment Failure, Unknown Mechanical Failure: Unknow

NS -1323 10/2/04 1.10 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Endicott Well Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1324 10/21/04 1.80 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Well Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1325 10/30/04 1.76 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -1326 11/20/04 1.20 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Well Equipment Failure, Line Failure Mechanical Failure: Other

NS -1327 11/30/04 3.30 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1328 12/04/04 25.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1329 12/07/04 1.52 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1330 12/23/04 1.80 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1331 01/09/05 1.31 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Corrosion Human Error: Unknown
A-23

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -1332 01/16/05 3.06 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1333 1/28/05 1.90 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1334 2/4/05 1.80 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Well Human Error Human Error: Unknown

NS -1335 02/04/05 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Corrosion Human Error: Unknown

NS -1336 02/13/05 15.71 C Refined: Other Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -1337 02/16/05 2.00 D Crude Mixture Crude Oil Oil Production Oil Production Unknown Milne Point Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1338 2/22/05 2.00 D Refined: Natural Gas Liquids Refined: Natural Gas Liquids Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Crack Mechanical Failure: Other

NS -1339 03/01/05 1.19 D Refined: Other Refined: Other Unknown Unknown Unknown Unknown Unknown Human Error Human Error: Unknown

NS -1340 3/12/05 15.50 C Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1341 3/14/05 5.40 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Tank Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -1342 3/16/05 3.60 D Refined: Diesel Refined: Diesel Bulk Fuel Terminal Support Facility/Services Onshore Prudhoe Bay Heavy Equipment Human Error, Overfill Human Error: Overfill

NS -1343 3/19/05 2.00 D Refined: Natural Gas Liquids Refined: Natural Gas Liquids Oil Production Oil Production Onshore Prudhoe Bay Other Crack Mechanical Failure: Other

NS -1344 03/26/05 170.66 C Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Unknown Corrosion Human Error: Unknown

NS -1345 3/30/05 7.70 D Refined: Diesel Refined: Diesel Oil Production Oil Production Offshore North Star Tank Human Error Human Error: Unknown

NS -1346 4/5/05 3.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Weld Failure Mechanical Failure: Other

NS -1347 4/12/05 30.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Weld Failure Mechanical Failure: Other

NS -1348 4/19/05 2.40 D Refined: Diesel Refined: Diesel Oil Production Oil Production Offshore North Star Well Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -1349 4/27/05 4.80 D Refined: Diesel Refined: Diesel Air Transportation Support Facility/Services Onshore Support Services Pipe or Line Human Error Human Error: Unknown

NS -1350 05/01/05 1.02 D Refined: Other Refined: Other Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1351 5/4/05 2.60 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Well Unknown Unknown

NS -1352 5/10/05 9.50 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Fuel Pump Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1353 5/22/05 1.80 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Unknown Unknown Unknown

NS -1354 6/3/05 9.50 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Well Equipment Failure, Line Failure Mechanical Failure: Other

NS -1355 6/3/05 2.40 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Well Weld Failure Mechanical Failure: Other

NS -1356 06/03/05 21.90 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1357 6/8/05 4.80 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Well Corrosion Mechanical Failure: Corrosion

NS -1358 6/11/05 2.90 D Refined: Diesel Refined: Diesel Bulk Fuel Terminal Support Facility/Services Onshore Prudhoe Bay Fuel Pump Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -1359 06/28/05 10.00 D Refined: Other Refined: Other Oil Production Oil Production Unknown Kuparuk River Unknown Human Error Human Error: Unknown

NS -1360 7/12/05 38.20 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Well Unknown Unknown

NS -1361 8/1/05 8.30 D Refined: Diesel Refined: Diesel Oil Exploration Oil Exploration Onshore Exploration Tank Puncture Human Error: Other

NS -1362 08/09/05 2.30 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Pipe or Line Corrosion Human Error: Unknown

NS -1363 8/11/05 3.30 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Colville River, AlpineWell Unknown Unknown

NS -1364 8/31/05 5.40 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Well Unknown Unknown

NS -1365 9/2/05 1.80 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1366 9/4/05 1.90 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Well Equipment Failure, Line Failure Mechanical Failure: Other

NS -1367 9/12/05 5.50 D Refined: Lube/Gear Oil Refined: Other Support Facility/Services Support Facility/Services Onshore Badami Unknown Human Error Human Error: Unknown

NS -1368 10/02/05 2.38 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1369 10/14/05 3.10 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Well Containment Overflow Human Error: Overfill

NS -1370 10/18/05 1.30 D Crude Oil Crude Oil Oil Production Oil Production Onshore Milne Point Pipe or Line Freezing Mechanical Failure: Other

NS -1371 10/29/05 10.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Offshore North Star Well Unknown Unknown

NS -1373 11/05/05 5.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1372 11/5/05 2.00 D Refined: Natural Gas Liquids Refined: Natural Gas Liquids Oil Production Oil Production Onshore Prudhoe Bay Well Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1374 11/14/05 1.19 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1375 11/29/05 1.30 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Well Corrosion Mechanical Failure: Corrosion

NS -1376 12/1/05 3.70 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Tank Human Error Human Error: Unknown

NS -1377 12/20/05 1.10 D Refined: Diesel Refined: Diesel Oil Exploration Oil Exploration Onshore Exploration Tank Equipment Failure, Gauge/Site Glass Failure Mechanical Failure: Other

NS -1378 01/09/06 3.57 D Refined: Other Refined: Other Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1379 1/10/06 3.60 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Heavy Equipment Collision/Allision Human Error: Other

NS -1380 01/11/06 1.91 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1381 1/17/06 8.90 D Refined: Diesel Refined: Diesel Oil Exploration Oil Exploration Onshore Exploration Other Cargo Not Secured Human Error: Other

NS -1382 01/17/06 1.24 D Crude Oil Crude Oil Oil Production Oil Production Unknown Milne Point Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1383 1/18/06 1.60 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Unknown Unknown Unknown

NS -1384 01/27/06 2.62 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1385 2/6/06 3.90 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Well Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -1386 2/9/06 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Human Error Human Error: Unknown

NS -1387 02/12/06 1.87 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -1388 2/26/06 4.30 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore North Star Tank Human Error Human Error: Unknown

NS -1389 3/2/06 5053.60 A Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Corrosion Mechanical Failure: Corrosion

NS -1390 3/25/06 4.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Well Human Error Human Error: Unknown

NS -1392 03/30/06 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Corrosion Human Error: Unknown

NS -1393 4/4/06 4.80 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal
A-24

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -1394 04/08/06 1.91 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1395 04/12/06 7.81 D Crude Oil Crude Oil Oil Production Oil Production Unknown Unknown Unknown Human Error, Overfill Human Error: Overfill

NS -1396 4/19/06 9.80 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Colville River, AlpineWell Unknown Unknown

NS -1397 05/02/06 5.34 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1398 05/07/06 9.52 D Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Human Error Human Error: Unknown

NS -1399 5/9/06 1.20 D Refined: Hydraulic Oil Refined: Other Vehicle Support Facility/Services Onshore Support Services Heavy Equipment Equipment Failure, Line Failure Mechanical Failure: Other

NS -1400 5/13/06 1.10 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Fuel Pump Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1401 6/8/06 2.40 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Tank Human Error, Overfill Human Error: Overfill

NS -1402 6/12/06 3.10 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Onshore Support Services Pipe or Line Equipment Failure, Vehicle Human Error: Other

NS -1403 06/22/06 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -1404 6/23/06 2.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Over Pressure Mechanical Failure: Overpressure

NS -1405 7/3/06 2.80 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Line Failure Mechanical Failure: Other

NS -1406 7/15/06 10.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Over Pressure Mechanical Failure: Overpressure

NS -1407 7/16/06 2.10 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Prudhoe Bay Tank Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1408 07/20/06 2.86 D Refined: Other Refined: Other Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1409 8/4/06 3.60 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Other Equipment Failure, Gauge/Site Glass Failure Mechanical Failure: Other

NS -1410 8/6/06 120.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Corrosion Mechanical Failure: Corrosion

NS -1412 08/07/06 4.77 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1411 08/07/06 1.79 D Refined: Other Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -1413 08/19/06 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Vehicle Accidents Human Error: Unknown

NS -1414 8/26/06 3.60 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Well Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1415 9/14/06 3.60 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Badami Tank Human Error Human Error: Unknown

NS -1416 9/18/06 15.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Well Weld Failure Mechanical Failure: Other

NS -1417 9/24/06 1.40 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Offshore Prudhoe Bay Other Human Error Human Error: Unknown

NS -1418 9/28/06 4.40 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Freezing Mechanical Failure: Other

NS -1419 9/29/06 1.90 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Line Failure Mechanical Failure: Other

NS -1420 10/09/06 1.60 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1421 10/13/06 1.20 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1422 10/24/06 1.20 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1423 10/31/06 220.00 B Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -1424 11/4/06 1.20 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1425 11/20/06 7.10 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Human Error, Overfill Human Error: Overfill

NS -1426 11/21/06 2.40 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Well Equipment Failure, Line Failure Mechanical Failure: Other

NS -1427 12/8/06 1.20 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Onshore Support Services Tank Rollover/Capsize Other

NS -1428 12/12/06 1.91 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1429 12/19/06 150.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Tank Weld Failure Mechanical Failure: Other

NS -1430 1/5/07 4.80 D Refined: Diesel Refined: Diesel Oil Production Oil Production Offshore Nikaitchuq Well Human Error, Overfill Human Error: Overfill

NS -1432 01/13/07 15.47 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1433 1/29/07 3.10 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Hydraulic SystemCrack Mechanical Failure: Other

NS -1434 2/1/07 1.30 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Human Error Human Error: Unknown

NS -1435 2/4/07 11.50 C Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Weld Failure Mechanical Failure: Other

NS -1436 2/6/07 2.60 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Badami Tank Containment Overflow Human Error: Overfill

NS -1437 02/08/07 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Unknown Unknown

NS -1438 2/13/07 4.80 D Refined: Diesel Refined: Diesel Air Transportation Support Facility/Services Onshore Support Services Tank Human Error, Overfill Human Error: Overfill

NS -1439 2/15/07 2.00 D Refined: Natural Gas Liquids Refined: Natural Gas Liquids Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Corrosion Mechanical Failure: Corrosion

NS -1440 03/03/07 11.90 C Crude Oil Crude Oil Oil Production Oil Production Onshore Milne Point Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1441 3/5/07 1.40 D Refined: Hydraulic Oil Refined: Other Air Transportation Support Facility/Services Onshore Support Services Heavy Equipment Equipment Failure, Line Failure Mechanical Failure: Other

NS -1442 3/31/07 1.30 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Milne Point Well Unknown Unknown

NS -1443 4/5/07 2.50 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Well Corrosion Mechanical Failure: Corrosion

NS -1444 4/8/07 165.00 C Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Onshore Prudhoe Bay Heavy Equipment Rollover/Capsize Other

NS -1445 4/9/07 2.40 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Milne Point Container, Other Human Error Human Error: Unknown

NS -1446 4/9/07 3.10 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Milne Point Pipe or Line Equipment Failure, Line Failure Mechanical Failure: Other

NS -1447 04/15/07 80.00 C Refined: Diesel Refined: Diesel Unknown Unknown Unknown Unknown Unknown Human Error Human Error: Unknown

NS -1448 4/19/07 8.30 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Pipe or Line Equipment Failure, Line Failure Mechanical Failure: Other

NS -1449 4/24/07 3.60 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Well Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -1450 5/3/07 1.90 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Milne Point Fuel Pump Equipment Failure, Line Failure Mechanical Failure: Other

NS -1451 05/22/07 2.07 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1452 5/23/07 3.50 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Offshore Endicott Other Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1453 05/28/07 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1454 6/6/07 7.00 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1455 6/15/07 3.00 D Refined: Hydraulic Oil Refined: Other Support Facility/Services Support Facility/Services Onshore Prudhoe Bay Hydraulic SystemEquipment Failure, Valve Failure Mechanical Failure: Valve/Seal
A-25

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -1456 6/16/07 4.80 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Hydraulic SystemEquipment Failure, Line Failure Mechanical Failure: Other

NS -1457 06/30/07 3.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1458 8/5/07 1.50 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1459 8/8/07 2.70 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Tank Containment Overflow Human Error: Overfill

NS -1460 9/5/07 1.30 D Refined: Diesel Refined: Diesel Oil Production Oil Production Offshore Oooguruk Pipe or Line Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1461 9/10/07 21.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Human Error Human Error: Unknown

NS -1462 9/10/07 2.40 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Other Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1463 9/29/07 1.30 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Tank Human Error, Overfill Human Error: Overfill

NS -1464 10/19/07 6.20 D Refined: Diesel Refined: Diesel Oil Production Oil Production Offshore Oooguruk Other Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1465 10/28/07 1.19 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1466 11/2/07 2.90 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Other Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1467 11/3/07 1.40 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1468 11/16/07 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Offshore Oooguruk Tank Human Error, Overfill Human Error: Overfill

NS -1469 11/22/07 10.70 C Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Line Failure Mechanical Failure: Other

NS -1470 12/7/07 1.80 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Other Human Error Human Error: Unknown

NS -1471 12/16/07 102.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Corrosion Mechanical Failure: Corrosion

NS -1472 12/28/07 3.30 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Drill Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1473 1/21/08 2.00 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Other Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1474 1/24/08 2.90 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Other Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -1475 2/10/08 1.70 D Refined: Hydraulic Oil Refined: Other Oil Exploration Oil Exploration Onshore Exploration Hydraulic SystemCrack Mechanical Failure: Other

NS -1476 02/10/08 6.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1477 2/21/08 20.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Colville River, AlpineTank Containment Overflow Human Error: Overfill

NS -1478 2/26/08 12.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1479 02/28/08 5.55 D Crude Oil Crude Oil Oil Production Oil Production Unknown Endicott Unknown Human Error Human Error: Unknown

NS -1480 3/11/08 3.60 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Support Services Tank Crack Mechanical Failure: Other

NS -1481 03/17/08 50.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Unknown Unknown

NS -1482 3/29/08 6.40 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Support Services Heavy Equipment Human Error, Overfill Human Error: Overfill

NS -1483 4/10/08 3.90 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Hydraulic SystemEquipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1484 04/15/08 1.19 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1485 4/17/08 2.90 D Refined: Hydraulic Oil Refined: Other Oil Exploration Oil Exploration Onshore Exploration Well Equipment Failure, Line Failure Mechanical Failure: Other

NS -1486 4/22/08 2.60 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Other Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -1487 5/8/08 10.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Human Error Human Error: Unknown

NS -1488 05/08/08 5.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Unknown Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1489 5/9/08 3.20 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Tank Human Error, Overfill Human Error: Overfill

NS -1491 05/09/08 3.57 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1490 5/9/08 8.30 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Other Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -1492 5/12/08 5.20 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Corrosion Mechanical Failure: Corrosion

NS -1493 05/14/08 1.78 D Refined: Other Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1494 5/17/08 4.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Colville River, AlpinePipe or Line Corrosion Mechanical Failure: Corrosion

NS -1495 05/23/08 5.24 D Refined: Other Refined: Other Support Facility/Services Support Facility/Services Unknown Unknown Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1496 5/26/08 1.10 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Support Services Tank Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1497 5/29/08 2.40 D Refined: Diesel Refined: Diesel Bulk Fuel Terminal Support Facility/Services Onshore Prudhoe Bay Unknown Unknown Unknown

NS -1498 6/2/08 1.40 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1499 07/02/08 2.00 D Crude Oil Crude Oil Oil Production Oil Production Unknown Colville River, AlpineUnknown Human Error Human Error: Unknown

NS -1500 7/16/08 20.20 C Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1501 7/17/08 7.10 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Hydraulic SystemEquipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -1502 7/30/08 3.30 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Heavy Equipment Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1503 7/30/08 2.50 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1504 8/1/08 1.60 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Human Error Human Error: Unknown

NS -1505 8/6/08 55.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Well Human Error Human Error: Unknown

NS -1506 8/9/08 3.80 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Well Weld Failure Mechanical Failure: Other

NS -1507 9/14/08 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Well Unknown Unknown

NS -1508 10/2/08 3.60 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Well Over Pressure Mechanical Failure: Overpressure

NS -1509 10/25/08 2.40 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Other Human Error Human Error: Unknown

NS -1510 11/08/08 4.00 D Refined: Other Refined: Other Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1511 11/15/08 2.40 D Refined: Lube/Gear Oil Refined: Other Support Facility/Services Support Facility/Services Onshore Prudhoe Bay Container, Other Cargo Not Secured Human Error: Other

NS -1512 12/25/08 452.00 B Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Pipe or Line Equipment Failure, Other Mechanical Failure: Other

NS -1513 12/27/08 2.00 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Nikaitchuq Hydraulic SystemEquipment Failure, Unknown Mechanical Failure: Unknow

NS -1514 1/7/09 23.80 C Refined: Diesel Refined: Diesel Oil Exploration Oil Exploration Onshore Exploration Tank Cargo Not Secured Human Error: Other

NS -1515 1/8/09 6.80 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Point Thompson Well Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1516 1/11/09 2.90 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Offshore North Star Pipe or Line Equipment Failure, Line Failure Mechanical Failure: Other
A-26

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -1517 1/12/09 96.40 C Crude Oil Crude Oil Oil Production Oil Production Onshore Milne Point Pipe or Line Freezing Mechanical Failure: Other

NS -1518 1/14/09 2.30 D Refined: Diesel Refined: Diesel Bulk Fuel Terminal Support Facility/Services Onshore Support Services Tank Human Error Human Error: Unknown

NS -1519 1/14/09 1.20 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Milne Point Drill Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1520 2/7/09 20.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Human Error, Overfill Human Error: Overfill

NS -1521 2/10/09 1.90 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Milne Point Well Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1522 2/18/09 46.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Corrosion Mechanical Failure: Corrosion

NS -1523 2/18/09 1.30 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Line Failure Mechanical Failure: Other

NS -1524 2/27/09 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Milne Point Tank Human Error Human Error: Unknown

NS -1525 03/11/09 4.76 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -1526 3/15/09 2.40 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Other Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1527 3/16/09 9.50 D Refined: Diesel Refined: Diesel Oil Exploration Oil Exploration Onshore Exploration Tank Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -1528 3/21/09 2.40 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1529 03/22/09 45.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Kuparuk River Unknown Equipment Failure, Valve/Seal Mechanical Failure: Valve/Seal

NS -1530 04/09/09 1.80 D Crude Oil Crude Oil Oil Production Oil Production Unknown Milne Point Unknown Human Error Human Error: Unknown

NS -1531 4/30/09 2.40 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Well Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -1532 5/13/09 1.70 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Tank Human Error, Overfill Human Error: Overfill

NS -1533 5/25/09 2.80 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Tank Equipment Failure, Line Failure Mechanical Failure: Other

NS -1534 6/24/09 1.80 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Well Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1535 6/26/09 1.80 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Over Pressure Mechanical Failure: Overpressure

NS -1536 07/09/09 1.50 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1537 7/20/09 10.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Weld Failure Mechanical Failure: Other

NS -1538 8/25/09 1.90 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Hydraulic SystemEquipment Failure, Line Failure Mechanical Failure: Other

NS -1539 8/27/09 2.40 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Support Services Unknown Unknown Unknown

NS -1541 11/08/09 2.86 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Corrosion Human Error: Unknown

NS -1540 11/8/09 4.80 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Well Unknown Unknown

NS -1542 11/19/09 1.90 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1543 11/21/09 6.00 D Refined: Natural Gas Liquids Refined: Natural Gas Liquids Oil Production Oil Production Onshore Prudhoe Bay Other Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1544 11/29/09 321.40 B Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Freezing Mechanical Failure: Other

NS -1545 12/02/09 34.00 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Pipe or Line Corrosion Human Error: Unknown

NS -1546 12/5/09 4.80 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Other Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1547 12/13/09 41.55 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error, Overfill Human Error: Overfill

NS -1548 12/21/09 2.40 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Over Pressure Mechanical Failure: Overpressure

NS -1549 01/02/10 3.14 D Refined: Diesel Refined: Diesel Oil Production Oil Production Unknown Kuparuk River Unknown Human Error Human Error: Unknown

NS -1550 1/13/10 4.30 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Tank Human Error, Overfill Human Error: Overfill

NS -1551 1/20/10 2.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Other Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1552 1/23/10 2.70 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Point Thompson Drill Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1553 1/27/10 3.80 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Line Failure Mechanical Failure: Other

NS -1554 1/30/10 1.80 D Crude Oil Crude Oil Oil Production Oil Production Offshore Oooguruk Fuel Pump Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1555 2/9/10 2.40 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Badami Tank Human Error, Overfill Human Error: Overfill

NS -1556 2/9/10 10.20 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Tank Human Error Human Error: Unknown

NS -1557 2/11/10 2.40 D Refined: Diesel Refined: Diesel Oil Production Oil Production Offshore Endicott Tank Corrosion Mechanical Failure: Corrosion

NS -1558 2/17/10 1.90 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Other Cargo Not Secured Human Error: Other

NS -1559 2/23/10 2.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Offshore Nikaitchuq Other Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -1560 3/5/10 6.60 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Nikaitchuq Tank Crack Mechanical Failure: Other

NS -1561 3/5/10 3.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Other Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1562 3/7/10 2.40 D Refined: Diesel Refined: Diesel Oil Production Oil Production Offshore Endicott Drill Human Error Human Error: Unknown

NS -1563 3/12/10 1.20 D Refined: Diesel Refined: Diesel Unknown Unknown Onshore Nikaitchuq Unknown Unknown Unknown

NS -1564 3/16/10 1.20 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Tank Equipment Failure, Tank Failure Mechanical Failure: Other

NS -1565 3/19/10 2.40 D Refined: Diesel Refined: Diesel Bulk Fuel Terminal Support Facility/Services Onshore Support Services Tank Human Error, Overfill Human Error: Overfill

NS -1566 3/21/10 1.10 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Drill Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1567 3/26/10 7.80 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Well Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1568 4/12/10 3.50 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Milne Point Heavy Equipment Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1569 4/17/10 4.50 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Well Collision/Allision Human Error: Other

NS -1570 5/18/10 2.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Well Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -1571 5/22/10 1.50 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Colville River, AlpineCoiled Tubing Unit Unknown Unknown

NS -1572 5/24/10 1.10 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1574 6/13/10 3.10 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Endicott Heavy Equipment Rollover/Capsize Other

NS -1575 6/19/10 1.40 D Refined: Diesel Refined: Diesel Waste Disposal Support Facility/Services Onshore Prudhoe Bay Heavy Equipment Human Error Human Error: Unknown

NS -1576 6/19/10 1.80 D Refined: Hydraulic Oil Refined: Other Waste Disposal Support Facility/Services Onshore Prudhoe Bay Heavy Equipment Human Error Human Error: Unknown

NS -1577 6/20/10 4.80 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1578 06/21/10 52.07 C Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other
A-27

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -1579 6/25/10 3.60 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Other Human Error Human Error: Unknown

NS -1580 7/3/10 3.50 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Tank Human Error Human Error: Unknown

NS -1581 7/5/10 1.90 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Tank Crack Mechanical Failure: Other

NS -1582 7/31/10 2.40 D Refined: Unknown Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Tank Human Error, Overfill Human Error: Overfill

NS -1583 9/11/10 8.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Tank Human Error Human Error: Unknown

NS -1584 9/17/10 1.70 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Heavy Equipment Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1585 9/20/10 1.20 D Refined: Diesel Refined: Diesel Bulk Fuel Terminal Support Facility/Services Onshore Support Services Tank Equipment Failure, Tank Failure Mechanical Failure: Other

NS -1586 9/24/10 1.40 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Hydraulic SystemEquipment Failure, Unknown Mechanical Failure: Unknow

NS -1587 11/4/10 1.10 D Refined: Lube/Gear Oil Refined: Other Support Facility/Services Support Facility/Services Onshore Support Services Drum(s) Human Error Human Error: Unknown

NS -1588 11/11/10 2.80 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Oooguruk Heavy Equipment Equipment Failure, Line Failure Mechanical Failure: Other

NS -1589 11/21/10 2.40 D Refined: Diesel Refined: Diesel Oil Production Oil Production Offshore Prudhoe Bay Other Rollover/Capsize Other

NS -1590 12/17/10 2.10 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Tank Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1591 12/29/10 2.40 D Refined: Diesel Refined: Diesel Bulk Fuel Terminal Support Facility/Services Onshore Support Services Fuel Pump Human Error, Overfill Human Error: Overfill

NS -1592 1/1/11 1.20 D Refined: Diesel Refined: Diesel Oil Production Oil Production Offshore Endicott Tank Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1593 1/3/11 4.40 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Tank Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -1594 1/8/11 8.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Unknown Well Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1595 01/23/11 1.19 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Unknown Unknown Unknown Human Error, Vehicle Accidents Human Error: Unknown

NS -1596 2/9/11 1.50 D Crude Oil Crude Oil Oil Production Oil Production Onshore Nikaitchuq Other Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1597 4/13/11 6.00 D Crude Oil Crude Oil Oil Production Oil Production Offshore North Star Other Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1598 5/18/11 3.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Well Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -1599 5/27/11 4.80 D Refined: Lube/Gear Oil Refined: Other Support Facility/Services Support Facility/Services Onshore Support Services Drill Crack Mechanical Failure: Other

NS -1600 6/25/11 1.30 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Other Unknown Unknown

NS -1601 7/21/11 1.40 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Corrosion Mechanical Failure: Corrosion

NS -1603 08/14/11 9.52 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Equipment Failure, Other Mechanical Failure: Other

NS -1602 8/14/11 1.20 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Offshore Nikaitchuq Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1604 08/16/11 4.53 D Crude Oil Crude Oil Oil Production Oil Production Unknown Prudhoe Bay Unknown Human Error Human Error: Unknown

NS -1605 9/5/11 11.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Tank Human Error, Overfill Human Error: Overfill

NS -1606 10/14/11 1.20 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Other Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1607 12/23/11 1.10 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Onshore Unknown Tank Rollover/Capsize Other

NS -1608 12/29/11 3.80 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Other Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1609 1/5/12 1.90 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Nikaitchuq Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1610 1/13/12 2.60 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Human Error Human Error: Unknown

NS -1611 2/6/12 26.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Badami Pipe or Line Human Error Human Error: Unknown

NS -1612 2/28/12 2.90 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Other Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1613 3/11/12 2.90 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Fuel Pump Human Error, Overfill Human Error: Overfill

NS -1614 3/31/12 2.30 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Support Services Drum(s) Human Error Human Error: Unknown

NS -1615 4/1/12 1.10 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Nikaitchuq Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1616 4/10/12 2.40 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Line Failure Mechanical Failure: Other

NS -1617 4/13/12 3.10 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1618 5/10/12 1.80 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Milne Point Other Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -1619 5/21/12 100.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Tank Containment Overflow Human Error: Overfill

NS -1620 5/22/12 7.10 D Refined: Diesel Refined: Diesel Bulk Fuel Terminal Support Facility/Services Onshore Support Services Tank Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1621 6/21/12 1.10 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Heavy Equipment Equipment Failure, Vehicle Human Error: Other

NS -1622 7/5/12 2.70 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Other Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1623 7/20/12 8.30 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Pipe or Line Equipment Failure, Line Failure Mechanical Failure: Other

NS -1624 7/30/12 1.10 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Colville River, AlpineHydraulic SystemEquipment Failure, Unknown Mechanical Failure: Unknow

NS -1625 7/31/12 1.80 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Tank Unknown Unknown

NS -1626 8/3/12 1.50 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Other Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1627 8/6/12 2.70 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Other Human Error, Overfill Human Error: Overfill

NS -1628 8/8/12 2.10 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Pipe or Line Human Error Human Error: Unknown

NS -1629 8/14/12 1.30 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Support Services Tank Cargo Not Secured Human Error: Other

NS -1630 8/19/12 3.60 D Refined: Turbine oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Other Human Error Human Error: Unknown

NS -1631 8/24/12 1.20 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1632 9/1/12 2.40 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Milne Point Hydraulic SystemEquipment Failure, Line Failure Mechanical Failure: Other

NS -1633 9/8/12 2.90 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Other Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1634 9/8/12 1.20 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Unknown Unknown

NS -1635 9/12/12 4.90 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Support Services Tank Human Error Human Error: Unknown

NS -1636 9/15/12 2.00 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Hydraulic SystemEquipment Failure, Unknown Mechanical Failure: Unknow

NS -1637 9/16/12 1.40 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Other Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1639 11/4/12 12.00 C Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Other Human Error, Overfill Human Error: Overfill

NS -1640 11/23/12 2.20 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Unknown Mechanical Failure: Unknow
A-28

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -1641 12/7/12 1.10 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1642 12/15/12 4.80 D Refined: Aviation Refined: Other Support Facility/Services Support Facility/Services Onshore Support Services Tank Human Error, Overfill Human Error: Overfill

NS -1643 1/3/13 14.30 C Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Support Services Drill Crack Mechanical Failure: Other

NS -1644 1/12/13 2.40 D Refined: Diesel Refined: Diesel Bulk Fuel Terminal Support Facility/Services Onshore Support Services Fuel Pump Human Error, Overfill Human Error: Overfill

NS -1645 2/19/13 3.70 D Refined: Natural Gas Liquids Refined: Natural Gas Liquids Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1646 4/3/13 1.20 D Refined: Diesel Refined: Diesel Oil Exploration Oil Exploration Onshore Exploration Other Unknown Unknown

NS -1647 4/5/13 2.10 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Unknown Unknown

NS -1648 4/8/13 14.90 C Crude Oil Crude Oil Oil Exploration Oil Exploration Onshore Exploration Pipe or Line Equipment Failure, Line Failure Mechanical Failure: Other

NS -1649 4/19/13 2.00 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Heavy Equipment Equipment Failure, Line Failure Mechanical Failure: Other

NS -1650 4/24/13 1.90 D Refined: Diesel Refined: Diesel Oil Production Oil Production Offshore Oooguruk Pipe or Line Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1651 5/15/13 1.70 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Tank Equipment Failure, Vehicle Human Error: Other

NS -1652 5/19/13 6.30 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Colville River, AlpineFuel Pump Human Error Human Error: Unknown

NS -1653 5/22/13 11.90 C Refined: Lube/Gear Oil Refined: Other Support Facility/Services Support Facility/Services Onshore Support Services Tank Equipment Failure, Tank Failure Mechanical Failure: Other

NS -1654 6/10/13 2.40 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Drum(s) Cargo Not Secured Human Error: Other

NS -1655 6/28/13 6.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1656 7/2/13 1.70 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1657 7/6/13 4.30 D Refined: Diesel Refined: Diesel Vehicle Support Facility/Services Onshore Support Services Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1658 7/19/13 1.20 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Colville River, AlpinePipe or Line Equipment Failure, Line Failure Mechanical Failure: Other

NS -1659 8/1/13 2.10 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Tank Human Error Human Error: Unknown

NS -1660 8/6/13 2.40 D Refined: Diesel Refined: Diesel Oil Production Oil Production Offshore Oooguruk Tank Human Error Human Error: Unknown

NS -1661 8/6/13 3.70 D Refined: Diesel Refined: Diesel Oil Production Oil Production Offshore Oooguruk Pipe or Line Equipment Failure, Line Failure Mechanical Failure: Other

NS -1662 8/17/13 1.20 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Unknown Unknown

NS -1663 8/18/13 1.30 D Refined: Diesel Refined: Diesel Oil Production Oil Production Offshore Nikaitchuq Tank Human Error Human Error: Unknown

NS -1664 8/19/13 1.40 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1665 9/24/13 166.00 C Crude Oil Crude Oil Oil Production Oil Production Onshore Milne Point Pipe or Line Unknown Unknown

NS -1666 10/9/13 3.60 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1667 11/9/13 3.60 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Well Equipment Failure, Line Failure Mechanical Failure: Other

NS -1668 11/22/13 9.20 D Crude Oil Crude Oil Oil Production Oil Production Onshore Nikaitchuq Container, Other Equipment Failure, Other Mechanical Failure: Other

NS -1669 12/12/13 6.50 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1670 12/20/13 71.40 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Colville River, AlpineTank Human Error, Overfill Human Error: Overfill

NS -1671 1/5/14 1.80 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Heavy Equipment Human Error Human Error: Unknown

NS -1672 1/6/14 43.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Well Corrosion Mechanical Failure: Corrosion

NS -1673 1/8/14 1.80 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Tank Human Error Human Error: Unknown

NS -1674 1/15/14 1.20 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Support Services Other Equipment Failure, Line Failure Mechanical Failure: Other

NS -1675 2/10/14 1.20 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Tank Unknown Unknown

NS -1676 2/20/14 1.20 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Pipe or Line Equipment Failure, Line Failure Mechanical Failure: Other

NS -1677 2/27/14 5.10 D Refined: Diesel Refined: Diesel Bulk Fuel Terminal Support Facility/Services Onshore Support Services Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1678 2/28/14 1.20 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -1679 3/19/14 5.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Point Thompson Container, Other Cack Mechanical Failure: Other

NS -1680 4/6/14 4.80 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Tank Equipment Failure, Tank Failure Mechanical Failure: Other

NS -1681 5/11/14 3.60 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1682 5/31/14 2.40 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Kuparuk River Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1683 6/2/14 4.60 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Tank External Factors Other

NS -1684 6/24/14 6.50 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Tank Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1685 6/25/14 7.80 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1686 7/16/14 2.10 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Unknown Unknown

NS -1687 8/29/14 6.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -1688 9/1/14 7.50 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Colville River, AlpineDrum(s) Human Error Human Error: Unknown

NS -1689 9/10/14 2.40 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Other Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1690 10/5/14 3.60 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Support Services Tank Equipment Failure, Gauge/Site Glass Failure Mechanical Failure: Other

NS -1691 11/6/14 1.20 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Well Unknown Unknown

NS -1692 12/4/14 1.30 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Heavy Equipment Equipment Failure, Line Failure Mechanical Failure: Other

NS -1693 1/24/15 3.30 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Point Thompson Tank Human Error, Overfill Human Error: Overfill

NS -1694 1/26/15 1.40 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Other Unknown Unknown

NS -1695 2/4/15 2.00 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Line Failure Mechanical Failure: Other

NS -1696 2/16/15 3.10 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Point Thompson Unknown Unknown Unknown

NS -1697 2/18/15 3.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Colville River, AlpineDrum(s) Human Error, Overfill Human Error: Overfill

NS -1698 2/28/15 117.60 C Crude Oil Crude Oil Oil Production Oil Production Onshore Milne Point Pipe or Line Corrosion Mechanical Failure: Corrosion

NS -1699 3/2/15 1.80 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Well Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1700 3/5/15 2.40 D Refined: Diesel Refined: Diesel Oil Exploration Oil Exploration Onshore Exploration Fuel Pump Equipment Failure, Valve Failure Mechanical Failure: Valve/Seal

NS -1701 3/10/15 3.40 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Support Services Tank Human Error, Overfill Human Error: Overfill
A-29

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -1702 4/5/15 1.90 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Nikaitchuq Hydraulic SystemEquipment Failure, Unknown Mechanical Failure: Unknow

NS -1703 4/26/15 4.80 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1704 5/15/15 1.50 D Crude Oil Crude Oil Oil Production Oil Production Onshore Milne Point Other Human Error Human Error: Unknown

NS -1705 6/18/15 2.40 D Refined: Unknown Refined: Other Support Facility/Services Support Facility/Services Onshore Support Services Container, Other Human Error Human Error: Unknown

NS -1706 6/26/15 9.80 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Tank Human Error Human Error: Unknown

NS -1707 6/26/15 3.20 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Other Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1708 8/21/15 9.00 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1709 9/24/15 4.80 D Refined: Lube/Gear Oil Refined: Other Support Facility/Services Support Facility/Services Onshore Support Services Container, Other Human Error Human Error: Unknown

NS -1710 10/3/15 1.50 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Tank Unknown Unknown

NS -1711 11/16/15 1.70 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Other Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1712 12/2/15 115.80 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Tank Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1713 12/8/15 2.40 D Refined: Hydraulic Oil Refined: Other Oil Exploration Oil Exploration Onshore Exploration Hydraulic SystemEquipment Failure, Unknown Mechanical Failure: Unknow

NS -1714 12/8/15 1.50 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Oooguruk Other Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1715 2/7/16 6.40 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Point Thompson Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1716 3/29/16 1.80 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Point Thompson Other Unknown Unknown

NS -1717 4/11/16 3.60 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Point Thompson Heavy Equipment Unknown Unknown

NS -1719 5/9/16 1.10 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Unknown Unknown

NS -1720 5/30/16 3.60 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Other Equipment Failure, Seal Failure Mechanical Failure: Valve/Seal

NS -1721 6/12/16 20.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Heavy Equipment Human Error Human Error: Unknown

NS -1722 8/7/16 1.60 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Well Unknown Unknown

NS -1723 9/18/16 2.50 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Point Thompson Drum(s) Human Error Human Error: Unknown

NS -1724 10/23/16 2.40 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1725 11/14/16 1.80 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Badami Other Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1726 11/30/16 2.90 D Crude Oil Crude Oil Oil Production Oil Production Onshore Nikaitchuq Other Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1727 12/10/16 2.50 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Other Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1728 1/3/17 2.90 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Milne Point Other Unknown Unknown

NS -1729 3/9/17 1.40 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Hydraulic SystemEquipment Failure, Unknown Mechanical Failure: Unknow

NS -1730 3/22/17 1.40 D Crude Oil Crude Oil Oil Production Oil Production Onshore Milne Point Other Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1731 3/30/17 8.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Well Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1732 4/14/17 5.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Well Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1733 4/22/17 1.40 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Kuparuk River Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1734 4/23/17 2.30 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Colville River, AlpineWell Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1735 6/2/17 1.70 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Hydraulic SystemEquipment Failure, Unknown Mechanical Failure: Unknow

NS -1736 6/17/17 100.00 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Oooguruk Well Unknown Unknown

NS -1737 6/26/17 2.90 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Well Unknown Unknown

NS -1738 6/29/17 1.30 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Oooguruk Unknown Human Error Human Error: Unknown

NS -1739 7/9/17 1.10 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Support Services Drum(s) Human Error Human Error: Unknown

NS -1740 7/30/17 3.90 D Crude Oil Crude Oil Oil Production Oil Production Onshore Kuparuk River Pipe or Line Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1741 7/31/17 1.30 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Unknown Unknown

NS -1742 8/22/17 1.20 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Support Services Unknown Unknown Unknown

NS -1743 8/24/17 1.20 D Refined: Diesel Refined: Diesel Support Facility/Services Support Facility/Services Onshore Support Services Drill Unknown Unknown

NS -1744 10/8/17 2.10 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Line Failure Mechanical Failure: Other

NS -1745 11/24/17 10.00 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1746 12/28/17 1.10 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Point Thompson Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1747 3/3/18 1.20 D Refined: Hydraulic Oil Refined: Other Support Facility/Services Support Facility/Services Onshore Support Services Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1748 7/3/18 2.40 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1749 7/23/18 1.10 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Heavy Equipment Human Error Human Error: Unknown

NS -1750 8/4/18 11.90 C Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Colville River, AlpineUnknown Human Error Human Error: Unknown

NS -1751 8/20/18 1.10 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Nikaitchuq Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1752 9/3/18 12.10 C Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1753 9/8/18 8.00 D Crude Oil Crude Oil Oil Production Oil Production Onshore Endicott Tank Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1754 10/9/18 2.40 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Milne Point Heavy Equipment Human Error Human Error: Unknown

NS -1755 11/4/18 2.50 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Colville River, AlpineWell Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1756 11/8/18 1.20 D Crude Oil Crude Oil Oil Production Oil Production Onshore Endicott Pipe or Line Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1757 12/11/18 1.50 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Other Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1758 12/15/18 2.60 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Other Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1759 12/23/18 4.80 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Unknown Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1760 1/30/19 1.30 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1761 3/20/19 1.90 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Kuparuk River Drill Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1762 4/14/19 7.90 D Refined: Lube/Gear Oil Refined: Other Support Facility/Services Support Facility/Services Onshore Support Services Tank Unknown Unknown

NS -1763 4/17/19 5.00 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Badami Tank Equipment Failure, Unknown Mechanical Failure: Unknow
A-30

 ID Date Size

(bbl)

 Size 

Class

Substance Consolidated 

Substance

Facility Type Consolidated Facility 

Type

Location Oil Field / 

Infrastructure

Source Cause Consolidated Cause

NS -1764 5/20/19 1.90 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1765 5/27/19 1.90 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Kuparuk River Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1766 5/28/19 2.40 D Crude Oil Crude Oil Oil Production Oil Production Onshore Milne Point Pipe or Line Equipment Failure, Line Failure Mechanical Failure: Other

NS -1767 6/10/19 2.40 D Crude Oil Crude Oil Oil Production Oil Production Onshore Prudhoe Bay Pipe or Line Equipment Failure, Line Failure Mechanical Failure: Other

NS -1768 7/22/19 1.50 D Refined: Lube/Gear Oil Refined: Other Oil Production Oil Production Onshore Prudhoe Bay Other Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1769 8/15/19 2.40 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Colville River, AlpineHeavy Equipment Human Error Human Error: Unknown

NS -1770 9/18/19 1.10 D Refined: Hydraulic Oil Refined: Other Oil Production Oil Production Onshore Endicott Heavy Equipment Equipment Failure, Unknown Mechanical Failure: Unknow

NS -1771 11/10/19 7.60 D Refined: Diesel Refined: Diesel Oil Production Oil Production Onshore Prudhoe Bay Unknown Equipment Failure, Unknown Mechanical Failure: Unknow
B-1

Appendix B: Exposure Variable Datasets 

Table B-1. Adjusted Alaska North Slope crude oil pricing, 1996–2019

Years

Price 

(millions of 

dollars)

Adjusted Price

(millions of 

dollars)

1996 15.3341667 25.2046933

1997 14.7825 23.7598552

1998 8.45 13.3809404

1999 12.6283333 19.5068096

2000 23.6733333 35.4538201

2001 18.1841667 26.5014464

2002 19.3733333 27.764764

2003 23.77 33.341524

2004 33.1366667 45.2175597

2005 47.3116667 62.4392979

2006 56.9691667 72.8873095

2007 63.7991667 79.232205

2008 91.235 108.957409

2009 54.8366667 65.8183551

2010 72.1683333 85.3736891

2011 98.4725 112.942437

2012 98.345 110.527222

2013 95.8433333 106.124652

2014 86.4525 94.1685876

2015 41.3433333 44.9985385

2016 33.2575 35.710172

2017 44.9358333 42.7021524

2018 62.575 60.9194094

2019 57.27 56.7592687
B-2

Table B-2. North Slope gas production per year, 1949–2019

Years Oil

(bbl)

Gas

(mcf)

Water

(bbl) Years Oil(bbl)

Gas

(mcf)

Water

(bbl)

1949 - 32,833 - 1985 - 1,310,297 - 

1950 - 90,790 - 1986 - 1,177,901 275 

1951 - 135,350 - 1987 - 1,211,948 1,030 

1952 - 136,545 - 1988 - 1,259,868 514 

1953 - 74,669 - 1989 - 1,232,346 446 

1954 - 27,129 - 1990 - 1,220,393 198 

1955 - 114,950 - 1991 - 1,244,400 72 

1956 - 103,462 - 1992 - 1,318,822 41 

1957 - 114,104 - 1993 - 1,285,809 34 

1958 - 118,555 - 1994 - 1,341,613 17 

1959 - 131,624 - 1995 - 1,259,915 - 

1960 - 172,426 - 1996 - 1,276,032 - 

1961 - 172,437 - 1997 - 1,280,850 - 

1962 - 196,734 - 1998 - 1,335,818 - 

1963 - 210,746 - 1999 - 1,458,807 - 

1964 - 248,953 - 2000 - 1,479,043 - 

1965 - 388,844 - 2001 - 1,475,473 - 

1966 - 437,513 - 2002 - 1,404,477 - 

1967 - 475,384 - 2003 - 1,416,809 - 

1968 - 503,725 - 2004 - 1,415,209 - 

1969 - 581,564 - 2005 - 1,387,270 - 

1970 - 618,616 - 2006 - 1,363,324 - 

1971 - 626,703 - 2007 - 1,333,417 - 

1972 - 674,871 - 2008 - 1,480,411 - 

1973 - 706,549 - 2009 - 1,649,758 - 

1974 - 764,919 - 2010 - 1,640,418 - 

1975 - 798,739 - 2011 - 1,576,449 - 

1976 - 831,824 - 2012 - 1,582,482 - 

1977 - 878,652 - 2013 - 1,574,458 89,360 

1978 - 892,844 - 2014 - 1,526,813 - 

1979 - 913,234 - 2015 - 1,603,970 - 

1980 - 1,027,416 - 2016 - 1,543,550 - 

1981 - 1,045,175 - 2017 - 1,526,456 - 

1982 - 1,249,314 - 2018 - 1,526,835 - 

1983 - 1,230,757 121 2019 - 1,517,881 - 

1984 - 1,343,143 - - - - 
B-3

Table B-3. North Slope oil production per year, 1969–2019

Years Oil

(bbl)

Gas

(mcf)

Water

(bbl)

Years Oil

(bbl)

Gas

(mcf)

Water

(bbl)

1969 277,377 242,956 78 1995 526,139,108 3,099,499,702 645,287,060

1970 1,199,414 1,038,765 2,006 1996 496,180,530 3,124,942,897 689,072,894

1971 1,156,812 888,907 339 1997 460,813,742 3,159,076,227 738,235,786

1972 922,147 657,936 - 1998 417,430,819 3,170,126,141 741,524,812

1973 943,698 699,460 - 1999 372,281,029 3,158,607,989 757,375,709

1974 2,169,876 2,022,246 246 2000 344,430,756 3,332,891,525 792,305,217

1975 2,869,559 3,046,347 429 2001 343,215,581 3,214,049,746 771,033,044

1976 4,604,449 5,076,913 1,550 2002 348,098,030 3,285,295,368 763,746,445

1977 115,257,880 94,935,524 2,428 2003 345,523,860 3,386,780,395 751,756,196

1978 397,678,542 307,965,694 1,326,005 2004 324,232,567 3,453,144,948 803,128,352

1979 468,412,351 432,474,776 8,098,013 2005 308,312,287 3,450,029,960 844,620,768

1980 555,394,181 597,147,564 13,819,549 2006 264,251,712 3,025,236,892 679,669,931

1981 556,264,022 648,385,506 14,638,092 2007 258,108,180 3,328,620,570 727,220,661

1982 591,502,613 780,246,482 15,320,634 2008 245,123,709 3,279,208,278 743,302,469

1983 600,805,736 863,544,092 40,165,852 2009 232,769,321 3,189,218,306 716,729,409

1984 608,453,818 904,485,106 59,080,400 2010 215,164,848 3,084,236,471 723,801,075

1985 649,612,731 1,043,180,924 86,748,162 2011 200,943,614 3,064,921,462 733,910,003

1986 664,051,772 1,095,803,371 141,007,476 2012 188,377,341 3,070,876,205 736,205,861

1987 699,527,264 1,426,769,917 242,591,979 2013 182,588,922 3,135,735,626 709,240,785

1988 722,839,521 1,654,378,949 309,835,913 2014 174,884,868 3,074,701,881 742,919,506

1989 669,258,145 1,667,525,750 357,149,099 2015 169,700,572 3,088,020,734 729,282,906

1990 636,366,508 1,752,257,239 418,446,005 2016 173,748,550 3,155,297,804 743,118,815

1991 641,048,345 2,082,756,966 488,770,878 2017 175,306,790 3,175,841,114 812,139,603

1992 612,162,058 2,329,690,170 574,852,036 2018 169,193,155 3,187,848,417 809,120,516

1993 564,092,990 2,499,503,190 621,797,239 2019 164,736,384 3,187,394,750 838,479,323

1994 553,402,838 2,790,256,928 612,803,268
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