V-/EPA
United States
Environmental Protection
Agency
Office Of Solid Waste
And Emergency Response
(5101)
EPA 550-R-96-002
September 1996
Expert Review Of EPA
Chemical Accident
Investigation Report
Terra Industries, Inc.
Nitrogen Fertilizer Facility,
Port Neal, Iowa
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EPA 550-R-96-002
September 1996
EXPERT REVIEW
OF
EPA CHEMICAL ACCIDENT INVESTIGATION REPORT
TERRA INDUSTRIES, INC. NITROGEN FERTILIZER FACILITY
January 1996
Chemical Emergency Preparedness and Prevention Office
Office of Solid Waste and Emergency Response
U.S. Environmental Protection Agency
Washington, DC 20460
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CONTEXTS
Foreword
Expert Review: Chair's Report
Names of Reviewers
Executive Summary, Background, Review, Recommendations
Appendix I Agenda of Reviewers Meeting
Appendix II Reviewers' Individual Comments
Appendix III Reviewers' Additional Remarks
EPA Response to Expert Review Recommendations
Appendix A: EPA's Charge to Reviewers
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FOREWORD
This document presents the comments and recommendations of five expert independent
reviewers, with whom EPA contracted to examine an EPA Chemical Accident Investigation
Report, "Terra Industries, Inc. Nitrogen Fertilizer Facility, Port Neal, Iowa." The EPA
investigation report was written by an investigation team at its Region VII office in Kansas
City and published in January 1996.
The Clean Air Act Amendments of 1990, Section 112(r), mandated the creation of an
independent Chemical Safety and Hazard Investigation Board (CSFflB) to investigate chemical
accidents and recommend steps to reduce the risk and hazards of chemical releases. However,
the CSHLB was never formed. In January 1995, the Administration asked EPA and OSHA,
under their own existing authorities, to investigate chemical accidents and issue public reports
containing recommendations on what the government, industry, and other stakeholders could
do to prevent similar accidents from occurring in the future. The EPA Terra Industries
Investigation Report is the first such report, dealing with a chemical accident in Port Neal,
Iowa in December, 1994. Since Iowa is one of 23 States having an OSHA State Plan: the
federal OSHA was not a joint investigator with EPA in this case.
In the spring and summer, 1996, EPA assembled a group of experts, charging them to
examine the scope, approaches, and methods of this first report to guide future studies and
investigations. Dr. Paul Hill of the National Institute for Chemical Studies served as Chair of
the review group.
The five reviewers independently examined the EPA report, documenting their analyses in
written comments. The Chair then circulated all comments to all reviewers, and convened a
meeting of the reviewers at EPA's regional offices in Kansas City to enable them to share
their comments from their different perspectives, to question the authors of the report, and to
examine photographs and other available documents. The Chair then wrote a summary of the
meeting and recommendations of the reviewers. This document includes copies of the
reviewers' comments, the Chair's summary, EPA's charge to the reviewers, and EPA's reply
to the reviewers' recommendations.
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Expert Review: Chair's Report
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National Institute
for Chemical Studies
A REVIEW OF USEPA'S
CHEMICAL ACCIDENT INVESTIGATION REPORT:
TERRA INDUSTRIES, MC.,
NITROGEN FERTILIZER FACILITY
PORT NEAL, IOWA
This document was prepared with support of
USEPA Order Number 6W-4075-TASA
by
National Institute for Chemical Studies
August, 1996
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REVIEWERS
DR. ISADORE (IRV) ROSENTHAL
The Wharton School of Decision and Risk
University of Pennsylvania
MR. JOEL R VARIAN
International Association of Machinists and Aerospace Workers
AFL-CIO (Retired)
MS. PAMELA NIXON, MS., MT.
CMA Public Advisory Committee
DR. GERALDINE V. COX
AMPOTECH
AMPOTECH Poland
DR. PAUL L. HILL (Chairman)
NICS
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EXECUTIVE SUMMARY
The NICS and Dr. Paul L. Hill, in conjunction with, Drs. Irv Rosenthal and Geraldine Cox,
Ms. Pamela Nixon and Mr. Joel Varian, were requested to conduct independent reviews of EPA's
investigative report on Terra Industries 1994 accident. In order to improve future reports as well as
future efforts to systematically collect data at accident sites, the review team offers the following
major recommendations for consideration:
EPA should;
• Include time lines in future reports.
• Expand and continue to model the scenario-by-scenario approach.
• Adopt or specify rigorous technical procedures sanctioned by the engineering
and research communities.
• Develop a defined protocol for accident investigations.
• Hold public meetings to seek stakeholders' input on the protocol.
• Consider accident oversight committees at affected sites which include public
liaisons.
• Initiate agreements with other federal, state, and local entities with accident
response authorities or consider legislative recommendations to accomplish
same.
• Create increased public and private awareness of it's investigative program.
• Clearly articulate the national goals and criteria for accident investigation.
• Draw upon the existing experience of NTSB and other agencies for assistance
in the evolving program.
Industry should;
• Take note and seriously address EPA's January 23, 1996 recommendations
for accident prevention.
• Initiate greater awareness of process safety regarding ammonium nitrate
through the research and engineering communities.
• Proactively embrace mechanisms for accident prevention.
States and Communities should;
• Initiate dialogue with industry and EPA to construct effective protocols
• Consider agreements for resource and authority coordination.
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BACKGROUND AND STATEMENT OF PURPOSE
At approximately 0606 hours on December 13, 1994, an explosion occurred in the ammonium
nitrate plant at the Terra International, Inc., Port Neal Complex. Four persons were killed as a direct
result of the explosion, and 18 were injured and required hospitalization. The explosion resulted in
the release of approximately 5,700 tons of anhydrous ammonia to the air and secondary containment,
approximately 25,000 gallons of nitric acid to the ground and lined chemical ditches and sumps, and
a large volume of liquid ammonium nitrate solution into secondary containment. Off site ammonia
releases continued for approximately six days following the explosion and drifted several miles.
Chemicals released as a result of the explosion have resulted in extensive environmental
contamination including groundwater under the facility.
The U. S. Environmental Protection Agency (EPA) Region VII was directed by EPA
Headquarters to conduct an investigation to determine the cause of the explosion and to develop
recommendations that would help prevent similar occurrences in ammonium nitrate production
facilities in the future. A report released by the Agency on January 23, 1996 contains conclusions
reached by the EPA chemical accident investigation team regarding the cause of the explosion at the
Terra International, Inc., Port Neal Complex and recommendations for prevention of future similar
occurrences. The investigation team from EPA was led by On-Scene coordinator (OSC) Mark
Thomas, Ph.D. of the Region VII Office with additional assistance defined in the report.
Shortly after the issuance of the report, EPA Headquarters initiated discussions with the
National Institute for Chemical Studies (NICS) to develop an independent review of EPA's
investigation and findings. As an independent non-profit organization with environmental, industry,
labor and community advocate constituents, NICS has a reputation for objective reports on chemical
accident prevention and preparedness. On March 5, 1996, EPA reached agreement with NICS to
oversee the review and designate Dr. Paul L. Hill as chairman of a proposed panel of individuals who
would conduct the review. Panelists were selected on the basis of their expertise in process
engineering, chemical safety, previous accident reviews and management disciplines as well as their
broad representation of different stakeholder perspectives. NICS developed a slate of potential
reviewers and provided the list to the Agency who selected and contracted with four (4) individuals
in addition to Dr. Hill. Reviewers were not asked or retained to conduct independent research in
order to supplement their technical knowledge and professional judgement or to verify the technical
information contained in the EPA Terra Industries Report. Reviewers and their affiliations are listed
on the previous page.
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Among the charges of the Chairman were to provide copies of the report to the reviewers,
solicit their written comments on the report, develop his own critique, distribute all five (5)
commentaries to each of the participants as well as EPA, organize a meeting to discuss their reviews,
chair the meeting and provide a final report of collective findings and recommendations to the
Agency. After the receipt of individual, initial comments in July, 1996, the Chairman called a
meeting on July 28-30, 1996 at the EPA Regional Office in Kansas City, Kansas. The review meeting
was attended by all five (5) members of the panel as well as EPA staff. (See Appendix 1).
The purpose of this meeting was not to form consensus on the issues of causality or absolute
recommendations to the agency. Rather, it was a forum to exchange ideas about the report's findings
and probe the records and recorded testimony for additional clarifications. Agency staff were present
by request of the Chairman to respond to questions and provide details of data collection, procedure
and scenario development used to compile the report. The charge of the review panel members was
quite narrow: (a) to assess the plausibility of the report findings based on all evidence collected by
the agency and (b) to make recommendations on procedure, technique and report formulation which
would improve future Agency accident investigation products.
The review team considered only the immediate information surrounding EPA's report, While
the team was aware of additional reports and documents developed by other parties, these were not
considered germane to the limited charge given by the Agency. In the possession of reviewers was:
(a) the settlement agreement between Terra International, Inc. and Iowa OSHA Employment Appeal
Board and (b) the Terra Port Neal Explosion report dated July 17, 1995 issued by a group of outside
experts retained by the General Counsel of Terra Industries, Inc. Technical and legal assertions
raised by the other parties involved in the Terra Industries, Inc. accident fell clearly outside the scope
of the review team's charge. No opinions are surmised or offered on these issues.
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THE REVIEW
Accident investigations and the attempt to reconstruct conditions which lead to an accident
are inherently difficult to pursue. The current report indicates that certain evidence, diagrams, and
requested documents were either destroyed or unavailable for this investigation report. Even with
satisfactory provision of existing management, operations and training materials, reliance upon human
knowledge and recollections as well as potential nondisclosure makes the job of accident investigation
for root cause all the more difficult. In light of the Clean Air Act Amendments of 1990, the review
team recognizes that as a nation, significant insights of investigation, and review, must be assessed
to fully implement the Act.
During the review meeting, held in Kansas City, the review team had unlimited access to
numerous photographs, drawings, analyses, transcripts and other evidence and documentation
collected by the Agency for development of the report. The team did not speak with any employee
of Terra International, Inc. and did not visit the accident site in Port Neal, Iowa. While a broader
investigation would have logically involved greater efforts to carry out these activities, this review
was limited to the January 23, 1996 report and the in-house information cited above. To more clearly
define the limited scope of this investigation report review, an outline of the key questions addressed
by the team are as follows. Reviewers were asked to:
a. Comment on the technical soundness.
b. Comment on the approach scenario by scenario.
c. Comment on the findings of the report and the most plausible scenario.
d. Comment on the comprehensiveness and reasonableness of the technical conditions
under which the accident occurred.
e. Are specific roles of certain equipment appropriately considered?
f. Is the discussion of ammonium nitrate (AN) appropriate?
a. Were all external factors considered in a proper way?
h. Comment on the overall conclusions and recommendations.
i. What activities or report components should be modeled for future investigations?
; Were prevention recommendations appropriately presented?
k. Were the roles of other entities appropriately addressed?
1. Are there additional recommendations for actions that could have been or should be
taken in the future?
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After providing initial comments and after meeting for a total of more than 18 hours, the
review team provided a series of comments about the report for the agency's consideration, These
comments, again, do not represent any absolute consensus of the team, in that many individual
stakeholder perspectives are included. However, the team was unanimous in its support that all
pertinent comments be offered to the Agency. In addition to individual comments provided by the
reviewers (which are included in Appendix 2 of this report), team commentary on the basic issue
questions cited above are intended to provide a constructive critique. Follow-up comments were
provided by two members of the team (See Appendix III).
APPROACH
Generally the team considered the overall approach to the report to be sound and appropriate.
The text was straight forward and lacked overly technical jargon which was considered beneficial for
public policy makers and the general public. Both constituent groups have expressed keen interest
in this report and it seems to be sensitive to these broad audiences. The "scenario by scenario"
approach used in the report is a valid and useful approach which was also viewed as helpful to the
reader.
In response to the question of whether this was the "correct" approach, this becomes a
philosophical discussion of the technical community on process safety and investigations. There exists
a vast literature on approaches to accident investigation as evidenced by a recent publication by the
Center for Chemical Process Safety (CCPS) of the American Institute of Chemical Engineers called
"Guidelines for Investigating Chemical Processing Incidents." While this document and others
describe numerous accepted approaches for accident investigation such as the one at Terra, the key
point of the review team was that a referenced, accepted methodology be utilized and clearly
described by the report (and future reports). After meeting with the OSC and others involved in the
investigation in Kansas City, it became apparent that several methodologies were considered. To the
reader of the report, and there are many, it is not readily apparent that such were utilized for this
investigation. All reports in the future should specify the process, procedure or guidelines within
which the investigation team was operating.
While the team viewed the "scenario by scenario" approach as useful and informative, it was
incomplete. Team members understood the need to truncate activities into a readable and concise
document. However, the omission of the range of scenarios (including sabotage) and why these were
dismissed should always be stated. Without questioning the investigators, reviewers had no indication
whether all scenarios had been considered and why/how same were dismissed.
The scenarios presented did a good job of systematically narrowing the scope of possibilities
for root cause based on evidence and good science. The use of a metallurgist was particularly helpful.
The overall findings of the report based on these scenarios and the evidence presented seem
reasonable to the entire review team. Given that Terra International, Inc. has presented a report with
slightly different findings relating to one piece of equipment (the sparger), this scenario could have
been pursued in greater detail (see sparger discussion).
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PLAUSIBILITY OF EPA CONCLUSIONS
Overall, the team agreed that EPA's conclusions were plausible given the evidence collected
and presented. It must be noted however that some evidence, samples and data were either destroyed
or never collected due to conditions under which the investigation took place. Lack of clear control
and coordination at the site seem to be primarily responsible for this. As the final report conclusions
indicate, several conditions at the plant were outside the range of standard or safe operating
procedures and parameters and led to this tragic accident.
The only reservation raised by the reviewers dealt with the issue of the sparger. The
committee was unable to come to consensus on the role the sparger did or did not play in the overall
stimulus of the explosion of the neutralizer. This single uncertainty however, does not negate the
reasonableness of the six conclusions put forward by EPA. There is significant evidence that
numerous problems existed at the facility. The review team's only concern with EPA's major
conclusions are of definition. That is, the conclusions themselves are less explanatory of "root cause"
than is the body of the report discussion. Since root causes are "prime reasons which lead to an
unsafe act or unsafe condition or constitute an underlying condition and result in an accident; if the
condition is removed the particular incident would not have occurred." Given this definition, the
management system failures that led to or allowed the existence of the unsafe acts or unsafe
conditions that the report concludes caused the accident was less than adequate. The report
discussion does a better job of identifying these causes than do, the conclusion and recommendation
sections of the report. Attention to the relationships between root cause and conclusions reached
would assist future readers and future reports.
COMPLETENESS
The team agreed that the investigators made a concerted effort to provide complete
information and analyses. Reviewers recognized that investigators were somewhat challenged by
the circumstances of cooperation, authority and coordination at the site. Given the conditions at the
Port Neal facility both before and after the December 13, 1994 explosion, the investigators did a
thorough job. While the review team initially raised questions regarding various technical issues (for
instance, sampling, sources of contamination of ammonium nitrate stocks and inert coatings of
vessels) these were sufficiently answered by the OSC and members of the investigation staff.
DISCUSSION OF CONDITIONS
Though historical records are not overly extensive on ammonium nitrate explosions, the report
discussion of pre-incident-conditions was both valuable and thorough. This discussion helped to
establish the plausibility of certain scenario building exercises which were undertaken by the
investigators. It also added value to the basis of discussion for non-technical stakeholders who have
or are likely to review the report. This type of background search on basic chemistry and literature
should be included in future reports.
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EXTERNAL ENTITIES AND FACTORS
Given that a clear lack of coordination with other agencies and interests existed during this
investigation, the report does not deal adequately with external factors. Only upon interview with
agency personnel was it apparent to the reviewers just how difficult this issue was. Because Iowa
is a designated "state OSHA" by its parent federal agency, coordination and, therefore, consideration
of more complete information exchange was greatly lacking. If detailed, coordinated investigations
and joint reports are to be achieved as intended by the CAAA of 1990, a broad protocol,
comprehensive in nature and definitive of the roles of all stakeholders must be developed. State
agencies, local response organizations, industry, labor and community advocates should be
coordinated by federal agencies into a cohesive, informed and collaborative effort. Externally, an
interface with all stakeholders would ensure accurate information is presented for public consumption.
Due to circumstances surrounding this particular report, these significant issues were not addressed,
ADDITIONAL ACTIONS
In its release of the report on January 23, 1996, EPA made several recommendations based
on its findings during the investigation. These ranged from recommending thorough process hazards
analyses, to reviews of safe operating procedures and increased emphasis on training, communication
and preventive maintenance. The review team supports these recommendations and notes that many
are now contained in OSHA and/or EPA regulations. From this incident, facility management must
recognize the value and meaning of compliance with existing rules and overall safe management
practices.
EPA should follow up with both the research community, trade associations and all
ammonium nitrate producers to fully inform them of the findings of this report. Additional research,
if properly structured should address ammonium nitrate sensitivity, confinement and activation. Also,
the emergency response community should be provided with detailed reviews of this accident and
how responders should prepare for responses to similar incidents.
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RECOMMENDATIONS
The Accident Report Review Team recommends that EPA assess its objectives and clearly
articulate a strategy to be commented upon by the various stakeholders. Major problems observed
in the Port Neal, Iowa investigation were (a) lack of understanding that EPA had authority to conduct
the investigation and (b) lack of coordination with other parties who also had interests or authorities
to collect information. These two issues precipitated most other deficiencies found in both the
investigation and the written report. Lack of clear authority and direction were the greatest
hindrances to EPA's staff.
The Team's recommendation for a uniform accident investigation policy should allow for
consideration of the numerous stakeholders including the public. Although the latter would not be
directly involved in evidence collection and technical work, the concept of an oversight committee
which includes public representation should be considered. Those parties or agencies with existing
authorities should be organized, through agreements or statutory changes, into a structured, mutually
beneficial approach. Recognized is the fact that EPA could be executing agreements with 50 states
plus countless local entities. In the Terra incident, a local fire chief, acting on his independent
authority, destroyed evidence by "hosing down" the area shortly after the event. Such seemingly
random actions will continue to occur at accident sites until a uniform protocol is issued.
Timing should be addressed also, as the agency's response did not begin until six days after
the event. While stabilization of the site was necessary and time consuming, the OSC was required
to develop an investigation strategy and implement that strategy impromptu. By this time, weather,
movement of debris, loss or destruction of evidence (e.g. the pry bar opening of 416J pump by Terra
personnel) or the actions of other agencies (e.g.. fire department) had degraded or eliminated
potentially critical evidence. The initial resistance of Terra personnel to take seriously the EPA
investigation team as demonstrated by the 26 site visits also slowed the initiation and completion time
of the investigation.
EPA should consider a national network of response capabilities and expertise as its accident
investigation program matures. In an effort to reduce costs, personnel or contract services with
particular expertise could be integrated into an overall approach at the direction of Headquarters
or among the Regional Offices. The previous recommendations regarding the expertise of other
agencies including OSHA, states, etc. should also be integrated into this potential network.
EPA should consider how it might leverage industry response to this and future reports.
Clearly, other ammonium nitrate producers will review this report for its implications on their
operations. However, other mechanisms such as working with trade associations or specific groups
like AICHE's CCPS, the Ammonia Institute, and others may provide a comprehensive yet focused
approach.
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Due to the nature of several key issues raised by the review team as well as the limited time
in which they had to consider the report, numerous issues remain unaddressed. The Agency should
continue to deal with these over time by seeking additional internal and external expertise on several
key subjects. Given the circumstances, EPA and particularly Mark Thomas of Region VTI, have
made a valuable contribution to the Agency's evolving investigative process. While inclusion of
analytical protocols, time lines and additional data may have improved EPA's Terra Industries report,
the content provides plausible support of the agency's conclusions and actions. Given the nature of
industrial facilities which handle hazardous materials and existing regulatory requirements, numerous
deficiencies surfaced at Terra's Port Neal operation. Based on the agency's evidence and the report,
an array of management, equipment, training and safety parameters were pushed beyond their safe
operating range. When this occurs, disastrous consequences are the result.
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APPENDIX
I
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PROPOSED AGENDA
TERRA INDUSTRIES - EPA ACCIDENT INVESTIGATION
REVIEW TEAM
July 28, 1996
July 29, 1996
July 30, 1996
Arrive Kansas City
5:00p.m.
8:00a.m.
8:30a.m. - 10:30a.m. -
Break
10:15a.m.-12:00p.m. -
12:00p.m.-l:30p.m. -
l:30p.m.-3:00p.m. -
Break
3:15p.m.-5:00p.m.
8:00a.m.
8:30a.m-10:30a.m.
Break
10:45a.m.-l:00p.m. -
Intro/Procedures
Dinner Meeting
Meet in Hotel Lobby for
Transportation To EPA
Mark Thomas
Questions & Examination
Material
Lunch
Panel Discussion
Panel Discussion
Meet for Transportation
Meeting with Mark Thomas
Final Discussion
Depart as individual schedules demand
Note: EPA Region VII and Headquarters staff will be on hand to assist the review team with
information, logistics or other assistance as needed Private (panel only) sessions are optional on both
days.
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APPENDIX
II
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National Institute
for Chemical Studies
for CHEMICAL ACCIDENT INVESTIGATION REPORT:
TERRA INDUSTRIES, INC.
NITROGEN FERTILIZER FACILITY
PORT NEAL. IOWA
REVIEWER'S COMMENTS
University of Charleston 2300 MacCorkle Avenue, SE. Charleston, West Virginia 25304
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A Review of
EPA Chemical Accident Report
"Terra Industries, Inc.
Nitrogen Fertilizer Facility"
by
Geraldine V. Cox, Ph.D.
under EPA Order Number 6W-463 7-NATA
Reference Number EAR203
Submitted July 15,1996
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Under contract to the United States Environmental Protection Agency, I reviewed the
Chemical Accident Investigation Report pntitW TFT?T?A TNDTTSTKTFS1 TNr
NITROGEN FERTILIZER FACILITY PORT NEAL.TOWA As background materials,
I also read the State of Iowa Occupational Safety and Health Citation documents and the
Report of the Incident Investigation Committee prepared by Terra on the Port Neal
Explosion, dated July 17, 1995.
EPA charged the reviews to respond to the questions that follow.
1. Comment on the technical soundness, overall approach, and completeness of the
report, to derive recommendations for approaches to accident investigations in the
future and accident prevention.
The overall approach was appropriate, but the number of possible scenarios was
somewhat truncated. All plausible scenarios should have been identified, and then
eliminated by data or reasoning. It appears that the "solution" to the cause was identified
early, and not all of the possible causes were identified and retained or eliminated as
appropriate. Or, if the scenarios were dismissed, it was not reflected in the report.
The Iowa OSHA citation indicated an evacuation that placed employees in the plume
of ammonia gas for a period of time following the incident. Understanding the charges to
EPA and OSHA regarding chemical safety incidents, I was surprised to see that the report
did not extend to the actions and plans following the incident. I would have expected to
see a discussion of the emergency response - both company and with local emergency
response teams. Was there any community exposure? Was there a review of the entire
post-incident events? If not, this should be included in the review. While information
from the response will not go to prevention, lessons learned from the response will be
valuable in the future to mitigate the effects of similar incidents.
The description of structures surrounding the plant is lacking. If there were no
surrounding structures, that should have been indicated.
2. Comment on the approach taken (scenario by scenario) as a correct approach to
take.
Scenario 1 - AN Plant Pumps
The discussion of the AN scrubber recirculation pump and the product pumps, based
on data presented, is plausible. I concur that the pumps were not the site of initiation.
Scenario 2 - AN Scrubber
This analysis seems valid based on the data presented. The AN scrubber was not a
source of the explosion.
Review of Chemical Accident Investigation Report by Geraldine V. Cox, Ph.D. 07/14/96
Terra Industries, Inc. Nitrogen Fertilizer Facility Port Neal Iowa Page 1 of 6
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Scenario 3 - Neutralizer
All data presented are consistent with an explosion originating in the neutralization
vessel. There was no discussion of the lining of the neutralization vessel, if any existed. If
the vessel was not lined with Teflon®, then the prolonged exposure to a pH of less than 1
might have introduced a local increased concentration of iron or chromium from the steel
tank that might have contributed to the reaction. There was no discussion of the materials
of fabrication of the pipes, and this might have contributed to activation of the reaction.
Since several of the metallurgical analyses indicated pitting, some degradation of the
vessel must have occurred before the explosion. Whether this contributed to the
explosion, or not, is unclear. In the report, there was a discussion of the abandoned steam
heating lines due to corrosion. What was the material of construction for the pipes, and
why did they corrode so badly that the steam lines could not be used? Was there a leak
that was causing the corrosion? If so, could that have introduced contamination?
Under item 2. of the determination of conditions prior to the explosion, the presence
of chlorides is mentioned. Was there a higher level of chromium and/or iron? These
compounds can also contribute to the explosion.
Spargers
The report did not discuss the "bathtub ring" that was mentioned in the Terra report.
Was any evidence of this "ring" found in the sample analyzed by EPA labs? There is a
clear discrepancy between the EPA and Terra report on this item. The EPA metallurgist's
report specified that the force originated outside of the sparger, not inside. Were
sufficient samples provided to the metallurgist to assure that the event was not triggered in
another section of the sparger. Since it appears that a single sample was analyzed, and the
ring had a rather large diameter, although unspecified in the report, could the initiation
been in another section of the sparger that was not analyzed?
The discussion of titanium "healing" is accurate and would argue against titanium
being an initiator, since the "reactive material" would be the relatively inert titanium
dioxide.
Neutralizer contents
Clearly the low pH, <1, contributed to the sensitization of the ammonium nitrate.
Since the pH sensors were isolated relative to the central portion of the reaction vessel, it
is difficult to understand if the contents were uniformly distributed, or channeled as
proposed by EPA. No one argues that bubbles were absent, and that the bubbles may
have contributed to the event. The scenario of local areas of convection with low pH,
contamination and bubbles is a reasonable explanation for initiation of the explosive
reaction.
Review of Chemical Accident Investigation Report by Geraldine V. Cox, Ph.D. 07/14/96
Terra Industries, Inc. Nitrogen Fertilizer Facility Port Neal Iowa Page 2 of 6
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5. Comment on the findings of the report examining various explosion scenarios and on
the identification of the most plausible scenario. Were any significant scenarios
missed?
The scenarios presented seem plausible, but the development of possible accident
scenarios seems somewhat truncated. For example, the normal approach to such an
accident investigation would normally list all possible, and often some improbable causes,
and then a method to eliminate those without substance based on data from the event.
This approach would structure the data collection effort, and would take place prior to
chemical and physical sampling at the site. One scenario, for example, should always be
sabotage. Most probably sabotage can be eliminated in this case, but it should always be
included in the analysis. For example, the chloride ion presence in the AN 83% storage
tank could have been introduced deliberately. (While I see no evidence that this occurred,
it cannot be ruled out.) Since the stainless steel neutralization tank was constructed from
304L stainless steel, with a high chromium content, 19%, combined with the fact that a pH
of less than 1 may have been present for a significant time, would possible chromium
contamination be a contributing factor. Chromium (and its oxo complexes) is a
sensitizing factor in ammonium nitrate decomposition reactions. If the vessel were
Teflon®-lined to prevent such solution of chromium and iron, it is not indicated in the
text. For that matter, iron could possibly contribute as a sensitizing agent as well.
The chloride contamination scenario does not seem to have adequate explanation. The
normal chloride content of water is less than 100 ppm, so the 557 ppm found in the nitric
acid absorption column seems very high. The description of the surface
condenser/absorption column was insufficient to understand how 557 ppm of chlorides
could accumulate. To contaminate the ammonium nitrate storage tank to the level of 157
ppm, a lot more chloride than found in drinking water would be necessary. Did anyone
calculate the total amount of chloride necessary to contaminate the Ammonium Nitrate to
a level of 157 ppm in the tank? I did not find the total capacity of the 83% Ammonium
Nitrate tank or the estimates of the amount of Ammonium Nitrate present in the tank at
the time of the incident. This would have been useful to determine the total amount of
chloride. If the volume of the tank were significant, then the amount of contamination
from chloride would be quite large, especially if it came from water.
Titanium is embrittled by ammonia. Was it possible that a high ammonia excursion
occurred sometime in the history of the system? With the pH probe function under
question, it is possible that the reaction was not controlled to a level where some
embrittlement did not occur - although it appears that the pH excursion was on the acid,
not alkaline range.
4. Comment on the comprehensiveness and reasonableness of the statements about
technical conditions under which the accident occurred. Are specific roles of certain
equipment, notably the sparger, appropriately considered?
Review of Chemical Accident Investigation Report by Geraldine V. Cox, Ph.D. 07/14/96
Terra Industries, Inc. Nitrogen Fertilizer Facility Port Neal Iowa Page 3 of 6
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As noted in the discussion of scenarios, the "bathtub ring" that Terra claims in the
sparger pieces found after the explosion, and from the sparger removed from the vessel
previously, this might have been a contributing factor. Was the sparger welded to form
the shape? If so, what was used in the welding process. Could it have contributed to the
failure? If the EPA conclusions about sparger integrity were based on a single sample,
and that sample was obtained from the other side of the vessel from the site of initiation, it
might not have the same characteristics. Therefore, multiple samples from different
locations of the sparger should have been analyzed. From the report it is unclear if
multiple samples were analyzed by EPA.
While the discussion of the materials of construction for the vessel and sparger were
good, the dimensions were absent. Also, the materials of construction for the piping of
the vessel were missing. The piping might be a possible source of contamination. Were
the vessels or pipes lined with an inert material such as Teflon®? Thickness of the tank
walls and sparger were not presented in the description. This would have been helpful.
5. With no prior history of accidental detonating of AN solution, is the discussion of the
conditions existing before the accident appropriate? Please comment on the
conclusions reached and whether they lead to the root causes identified..
The discussion of the pre-incident conditions was very thorough. The discussion
could have been stronger if the sizes of the involved vessels were identified, as well as the
materials of construction of the pipes, and an indication of whether the neutralization tank
was lined and the thickness of the respective vessels.
In Figure 2-2,1 believe that the arrow head is pointing in the wrong direction on the
line connecting the urea and 83% AN sales line. I believe the AN flow goes to the
nitrogen solutions storage where it is mixed with urea. In fact, the line should go directly
to the storage tank, where I believe it is mixed with urea, rather than flowing into the urea
line.
The possible contamination of the reactive materials should have included chromium,
and possibly iron. The discussion of sensitizing agents mentions these materials, and there
is a possibility that they could be present due to construction materials, so they should
have been included, A discussion of the concentration of these contaminants as
concentration alters the reaction would have been helpful.
6. Were all externalfactors considered in a comprehensive way? Also, please comment
on whether human factors and broad management issues were identified
appropriately, in appropriate sequences, in ways to lead to reasonable conclusions
and recommendations.
As stated earlier, the report should have included a review of the actions taken after
the incident. This should have included employee evacuation procedures and the role of
Review of Chemical Accident Investigation Report by Geraldine V. Cox, Ph.D. 07/14/96
Terra Industries, Inc. Nitrogen Fertilizer Facility Port Neal Iowa Page 4 of 6
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the plant personnel with local emergency response and planning groups and any
community surrounding the plant.
The mention of the corroded steam pipes, to the point where the pipes were unusable,
bothers me. What caused the corrosion and could the leaks have contaminated the
system. From the limited description, it is impossible to understand if they contributed to,
or were symptomatic of other problems that this report did not identify.
The high concentration of chloride seems to be hard to explain on the basis of water
contamination. The mass of chloride ion should be calculated to understand the extent of
contamination. Is there a possibility of sabotage? From the operations history, I do not
believe there was sabotage, but it should still be considered and ruled out based on the
data.
The pre-incident report mentions an "outside operator" who was present, and is
present in startup and shutdown operations. It was unclear if this individual was a Terra
employee or a contract employee. Did this individual receive the same training as the
Terra full-time operators of the ammonium nitrate unit? What is the full role of the
outside operator, and what is the familiarity of this individual with the process? This could
possibly be a source of error, especially because Terra apparently did not have written
shutdown and startup procedures.
7. Please comment on the conclusions and recommendations. What of the overall
approach could be modelled for future such investigations? Was information for
prevention of similar accidents appropriately presented in this report?
The conclusions are valid, and the rationale for the conclusions seems to be sound.
The recommendations highlight the poor documentation of the facility in terms of written
procedures. If the facility had been conforming to OSHA 1910, this incident would most
likely not have occurred. However, the possible degradation of the sparger might have
contributed to the system failure even if these procedures were in place. There is no
reason why a suspected faulty pH probe could not have been replaced within the time
period, although if the tank were not discharging, then it would be of little use since it was
outside of the neutralization tank. I question whether the fluctuations in the readings that
Terra employees believe was due to a faulty probe might have, in fact, been accurate and
the pH fluctuation might be longer than stated in the incident report,
In recommendation 3., the startup procedure should be specified as well as shutdown
In recommendation 4., the engineer should not only approve changes, he should sign
off on any changes so the documentation is incontrovertible.
In recommendation 6., any outside contractors should be included in the training
program. Anyone who works in the unit should have training and understand the
Review of Chemical Accident Investigation Report by Geraldine V. Cox, Ph.D. 07/14/96
Terra Industries. Inc. Nitrogen Fertilizer Facility Port Neal Iowa Page 5 of 6
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procedures. This training should include what type of safety equipment is appropriate,
and that equipment should be available.
8. Concerning the role-offederal, state local agencies; the public; labor; trade
associations; andpublic interest groups: please comment on whether roles of these
entities were appropriately addressed. Are there any recommendations for actions
they could have taken, or should in future take to reduce accident risks?
The role of the local emergency responders was not addressed at all. The EPA
report was thorough, but seemed more appropriate for OSHA than EPA. However, in a
quick reading of the Iowa Occupational Safety and Health Department citation, they did
not prepare a causative report of the depth of EPA. This type of report should be done,
and it is worth an understanding on a national level when states have OSHA primacy, such
as Iowa. Perhaps the federal OSHA should review the EPA report or the state citation in
cases where explosions in chemical operations cause death.
Labor is not part of the review process, although there is a strong national
program in worker safety run by the AFL-CIO. Perhaps in future incidents, one of their
technical staff can be included on the review panel for EPA.
The Fertilizer Institute should receive this report and be asked to develop an
approach for its members to prevent similar incidents. Trade associations can be valuable
allies in understanding events such as this and to develop viable approaches to preventing
similar incidents or at least mitigating the consequences. There was no mention of any
industry-wide practices for this type of operation.
No mention of public interest groups was made in the report, however,
incorporation of the local emergency planning commission should include an outreach to
the public interest groups most likely to be effected by the facility operations,
/
/
Geraldme V. Cox, Ph.D
Review of Chemical Accident Investigation Report by Geraldine V. Cox, Ph.D. 07/14/96
Terra Industries, Inc. Nitrogen Fertilizer Facility Port Neal Iowa Page 6 of 6
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07/18/9612:04 FAX 7668481 CAREPOINT LAB
Review of EPA
Chemical Investigation Report
Terra Industries, Inc.
Pamela Nixon, MS MT (ASCP)
The investigation of Terra Industries, Inc. of Port Neal, Iowa, by EPA appeared to to be
thorough. The investigation team's recommendations were focused primarily on the
ammonium nitrate (AN) unit, due to the > 1 explosion that occurred there. However, the
historical data of the most recent incidents that lead up to the event, indicated that plausible
contributing factors could have come from the feed streams including Area I and Area II
as described in Section 2: Background:
In Section 10: Recommedations, the investigation team's recommendations (#1 through
#5 and # 8) could possibly be augmented to include the units of Areas I and II.
Recommendations #6 & #7 appear to be more broad-based, and not specific to the AN
unit
In reading the recommendations, I have taken them literally thereby, possibly interpreting
them more narrowly than the investigation team intended My experience has been to look
at industrial accidents from outside the fence-line. When discussing accidents with company
officials I have discovered that they respond to the literal interpretation of questions and
recommendation, and that is why I have chosen this route.
In Section 2: Background, Area I and Area II are differentiated into distinct smaller plants which
include the ammonia plant, tank farm, utilities, nitric acid plant, the urea plant, and the AN
plant. These smaller plants are either feed streams or they lead-off the AN plant
' Petroleum spills in the ammonia plant (September 1994 and October 1994), possibly
causing the hydrocarbon contamination
* Water leak in the Nitric Acid plant (December 5 to 8, 1994) possibly being the con-
tributing factor of chloride contamination
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07/16/96 12:04 FAX 7688481 CAREPOINT LAB
page 2 of 3
• Uncontrolled off-gas flow production of ammonia from the Urea Plant to the AN
neutralize^ possibly affecting the pH in the neutralizer and being responsible for the
the ammonia leak during the several days that followed the explosion
It is EPA's responsibility to protect the public from similar events that may impact their lives
in an negative manner. In order to minimize such occurances, I believe the recommen-
dations should be inhanced to include the following:
* I suggest that the PA of the AN plants (recommendation 1) be expanded to include
PA of all Plants, storage units, and utilities as described in Area I and Area II
Section 2: Background. If the AN plant lacked completed PA, there is possibly the
need for performed on the Terra Industries facility as a whole, or to show
documentation that it has been performed as changes have occurred in other areas.
* I suggest that the safe process operating parameters for the AN plants (recommen-
dation 2) be expanded to include all plants, storage units, and utilities as described
in Area I and Area II Section 2: Background rather than only monitoring the
feed streams for the presence of known contaminants on a periodic basis as well as
periodically reevaluating operating parameter ranges, or provide documentation that
it already exists in the other area.
" I suggest that the development of the written, safe operating procedures for the AN
unit (recommendation 3) be expanded to include all plants, storage units, and utilities
as described in Area I and Area II and Area II in Section 2: Background and the procedures
should be developed for activities conducted in each unit in all modes of operation,
including periods when the units are shut down and the vessels are charged... If
written, safe operating procedures exist in the other united provide the documents.
* I suggest that 4 complete management of change procedure for all operating
parameter range changes for the AN unit (recommendation 4) be expanded to
include all plants, storage units, and utilities as described in Area I and Area II in
Section 2: Background, and this should include approval to operate the unit outside
of approved parameter ranges by the engineer responsible for these units, and docu-
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07/16/96 12:01 FAX 7668481 CAEEPOINT LAB
page 3 of 3
mentation of these activities - If written, safe operating procedures exist in the
other units, provide the documents.
• I suggest the development of the maintenance program that will anticipate problems
in the AN unit (recommedation 5) be expanded to include all plants storage units,
and utilities as described in Area I and Area II in Section 2: Background. This
program should include predictive failure analyses - If this program exists in the
other units, provide documents.
• I suggest that information on the hazards of substances handled, the prevention
measure a in place or planned to prevent releases and the emergency response
measure a (recommendation 8) be taken for all plants, storage units, and utilities (as
described in Area I and Area II Section 2: Background) with the State Emergency
Response Commission, Local Emergency Planning Committee, first responders, and
the public surrounding the facility. If this information from the other units has been
given to the above mentioned agencies, provide the documentation.
I feel that if the recommendations are not explicit to include the other units, the programs
procedures and training in the other units may be overlooked. Then the potential for an
incident of equal or greater magnitude occuringin other units of Terra Industries, will
continue to be list
There should be a system in place where by OSHA and EPA can work together on a safety
board to protect the health, safety, and environment of the workers and the public.
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Review of the EPA Region VII Report on the 12/13/94 Accident
at the Port Neal, Iowa Facility of Terra Industries.
Isadore Rosenthal, Ph. D., 7/14/96.
Scope of the report.
This report is organized around the specific areas that reviewers were
asked to address in the "Charge to Reviewers" and " Statement of Work
for Expert Reviewers" (Appendix I).
The general charge to reviewers was to "use your technical knowledge and
professional judgement to comment on the technical soundness, overall
approach, and completeness of the report, to derive recommendations for
approaches to accident investigations in the future and accident
prevention." The report on which the reviewers were to comment was
Region VII's report on the accident at the Terra Industries facility in
Port Neal, Iowa (EPA Terra Report).
Reviewers were not asked or retained to do independent research in order
to supplement their "technical knowledge and professional judgement" or
to verify the information contained in the EPA Terra Report being
reviewed.
Two additional documents dealing directly with the Terra Industries
accident were supplied to this reviewer in connection with his
assignment:
9
1. The settlement agreement between Terra International, INC. And
the Iowa OSHA Employment Appeal Board (OSHA - Terra Agreement).
2. The July 17, 1995 report on the accident at the Terra Industries
facility in Port Neal prepared by a group of outside experts retained
by the General Counsel of Terra Industries Inc (Terra Port Neal
Report).
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This report is organized around the following specific items that the
"Charge to Reviewers" asked each reviewer comment on:
1.- Whether the scenario by scenario approach taken was correct.
2.- The findings of the report examining various explosion scenarios.
3.- The identification of the most plausible scenario.
4.- The omission of significant scenarios.
5.- The comprehensiveness and reasonableness of statements about
technical conditions under which the accident occurred.
6.- The appropriateness of the consideration given to the roles of
certain equipment, notably the sparger.
7.- Is discussion of the conditions existing before the accident
appropriate with no prior history of the accidental detonating of AN
solution"?
8.- The conclusions reached and whether they lead to the root causes
identified.
9.- Were all external factors considered in a comprehensive way?
10.- Whether human factors and broad management issues were
identified appropriately, in appropriate sequences, in ways to lead
to reasonable conclusions and recommendations.
11.- The conclusions and recommendations.
12.- What part of the overall approach could be modeled for future
such investigations?
13.- Was information for the prevention of similar accidents
appropriately presented in this report?
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14.- Were the roles of federal, state local agencies; the public; labor;
trade associations and public interest groups appropriately
addressed?
15.- Recommendations for actions they (federal, state local
agencies; the public; labor; trade associations and public interest
groups ?) could have taken or should in the future take to reduce
accident risks
1 .- Comments on whether the scenario by scenario approach
taken was correct.
This reviewer feels that the "scenario by scenario approach" used in
Region, VIFs report on the accident at the Terra Industries facility in Port
Neal, Iowa (EPA Terra Report) is a valid approach.
However, there is no such thing as a "correct" approach.
There is a vast literature on approaches to accident investigation. A
relatively recent authoritative survey of this literature and its learnings,
"Guidelines for Investigating Chemical Processing Incidents ", has been
published by the Center for Chemical Process Safety (CCPS) of the
American Institute of Chemical Engineers (CCPS Guidelines). These
"Guidelines" describe numerous different 'accepted' approaches for the
investigation of accidents similar to the one that occurred at the Terra
facility. Each of these accepted approaches is used and endorsed by
different reputable authorities.
2. - The findings of the report examining various explosion
scenarios.
The findings of the report examining various explosion scenarios seem
reasonable given the information presented in the EPA Terra report with
the possible exception of some of the findings related to the Sparger (see
comments in item 6)
3.- The identification of the most plausible scenario.
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The physical findings after the accident indicated that there were two
explosions the first of which occurred in the Neutralizer and the
subsequent one in, the Rundown tank.
Three of the four scenarios presented dealt with possible sequences of
events, and conditions related to the initial explosion. The third of these
four scenarios, which dealt with initiation within the Neutralizer was
sub-divided into two scenarios, one dealing with decomposition
originating within the nitric acid Sparger, the other with decomposition
originating in the contents of the Neutralizer tank external to the nitric
acid sparger.
The fourth scenario was the only scenario that dealt with the second
explosion which occurred in the Rundown tank.
This reviewer agrees with the EPA Terra Reports conclusion that scenario
3 was the most plausible of the three scenarios for the first explosion and
that scenario 4 was plausible.
However based on information presented in the Terra Port Neal Report,
there are questions which need further analysis before this reviewer is
comfortable with choosing which of the two sub- scenarios considered
under scenario 3 is most plausible.
4. - The omission of significant scenarios.
Based on the information available this reviewer does not believe that
significant scenarios were omitted, though perhaps sub-scenario 3 might
have been broadening given the information maintained in the subsequently
issued Terra Port Neal Report( see specific comments under item 6
dealing with the considerations given to the role of the Sparger).
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5.- The comprehensiveness and reasonableness of statements
about technical conditions under, which the accident occurred.
Overall the comprehensiveness and reasonableness of statements about
technical conditions under which the accident occurred was good given the
conditions and less than complete documentation and records that
apparently existed at the Terra Port Neal facility before and after the
12/13/94 accident.
6. - The appropriateness of the consideration given to the roles
of certain equipment, notably the sparger.
Based on the information given in the EPA Terra report in regard to
possible role of titanium and in particular the statement on p. 86 of this
report which states that "The forces that distorted and destroyed the
Spargers were applied to the external surface, not the interior surface",
this reviewer initially believed that appropriate consideration was given
to the role of other equipment, notably the sparger.
However some doubts were raised in regard to this reviewer's initial
belief on the appropriateness of the consideration given to the role of the
sparger by the information in the Terra Port Neal Report. This report
contained information related to the possible sensitization role of
titanium and in particular the statement (Exhibit 8, p. 8) that "The
titanium fragments provided evidence that the acid sparger had ruptured
due to internal overpressurization. In addition, most of the interior and
some of the exterior surface of the fragments showed corrosion".
7.- Is discussion of the conditions existing before the accident
appropriate with no prior history of the accidental detonating
of AN solution"?
The simple answer to this question is yes, though this reviewer- has
difficulty with the meaning of this question. Clearly there have been
previous AN solution explosions at other locations. Given that it has been
established that AN and its solutions have this potential for injury and
that the amount of AN (and other highly hazardous substances) being
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processed at the Port Neal facility that could give rise to major
accidents, discussion of the conditions existing before the accident seem
appropriate to this reviewer.
8. - The conclusions reached and whether they lead to the root
causes identified.
The one significant reservation that this reviewer has on the conclusions
put forward in the EPA Terra Report rests conditionally on the resolution
of questions raised above concerning the role of the sparger. However even
if the Sparger is shown to have played a more significant role in initiating
the explosion in the neutralizer, this would not negate the reasonableness
of the six conclusions put forward.
The conclusions reached in Section 9 of the EPA Terra Report deal
adequately with the "unsafe acts or unsafe conditions" resulting from
employee action or inaction. However this reviewer believes that the
conclusions reached in Section 9 of the EPA Terra Report EPA Terra Report
deals less than adequately with Root causes.
This reviewer's definitions of 'Root' causes is;
"Prime reasons, such as failures of some management systems, that
allow faulty design, inadequate training or improper changes, which
lead to an unsafe act or unsafe condition and result in an incident.
Root causes are also known as underlying causes. If root causes
were removed, the particular incident would not have occurred."
Given this definition, the management system failures that might have led
to or allowed for the existence of the unsafe acts or unsafe conditions
that the report concludes led to the accident was less than adequate. The
body of the EPA Terra Report does a much better job in relating
management system failures to the factors that presumably led to the
accident than do the recommendations.
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In the reviewers opinion, use of a presentation approach such as the MORT
based Root Cause Analysis Form 7 would more clearly show relationships
between Root causes and the conclusions reached in. the EPA Terra Report.
9.- Were all external factors considered in a comprehensive
way?
This question is unclear to the reviewer What are examples of the
external factors that were to be considered? The weather? Power
failures? Possible health epidemics in the community that affected
employees or management in an unforeseeable fashion?
10.- Whether human factors and broad management issues were
identified appropriately, in appropriate sequences, in ways to
lead to reasonable conclusions and recommendations.
The body, of the EPA Terra Report contained the information required to
ensure that human factors and broad management issues were identified
appropriately, in appropriate sequences, in ways to lead to reasonable
conclusions. However this information was less than adequately.
summarized and related to the conclusions and recommendation made in
Sections 8 and 10. (See comments under item 8 and 10).
11.- The conclusions and recommendations.
This reviewer commented in item 8 on the conclusions given in Section 9
of the EPA Terra Report. However there is an additional conclusion given
in the first paragraphs of Section 10, Recommendations. While this
reviewer agrees that the EPA Terra Report presents evidence that the lack
of safe operating procedures was an important factor in the sequence of
events leading to the accident, it is somewhat disingenuous to claim that
"the conditions that caused the explosion existed primarily (emphasis
added) 'because of the lack of safe operating procedures'without
defining "safe operating procedures" operationally.
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To this reviewer "safe operating procedures" can only be developed and
implemented after a facility implements all of the eight specific
numbered (1 to 8) recommendations made in Section 10. All of these
recommendations appear to be in order and are generally considered to
constitute 'good practice' for facilities handling the quantities and type
of materials and processes present at the Terra' Port Neal facility.
12.- What part of the overall approach could be modeled for
future such investigations?
EPA should adopt a standard Type 3 accident investigation protocol for all
of its accident investigations. Most of such approaches include almost all
of the elements in employed in the "scenario by scenario" approach used
in the Region VII investigation but in a more structured way.
This protocol should be modeled after one of the broadly accepted
multiple-cause, system oriented investigation approaches in the public
domain that is focused on the determination of 'root' causes. To the extent
consistent with its constraints, this standard EPA protocol should use the
terminology, methodology and presentation styles used in the literature
associated with the broadly accepted multiple-cause, system oriented
investigation approach used as model for EPA's standard protocol.
If this approach is feasible, EPA will achieve greater clarity,
understanding and acceptance of its investigations in the technical
community and will benefit from the continuing research work that the
broad technical community does on the particular Type 3 model that EPA
uses as the basis for developing its own standard protocol.
13.- Was information for the prevention of similar accidents
appropriately presented in this report?
See comments under items 3, 6, 8, 10 & 11 above.
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14.- Were the roles of federal, state local agencies; the public;
labor; trade associations and public interest groups
appropriately addressed?
This reviewer could not locate sections of the EPA Terra Report that
addressed roles for Federal, state local agencies; the public; labor; trade
associations and public interest groups other than recommendation that
imply that Terra Industries should supply information to the public
surrounding the facility and state and local agencies dealing with
emergency response (recommendation. 8, section 10).
In this reviewers opinion this does not appropriately address the roles
that all elements of federal, state local agencies; the public; labor; trade
associations and public interest groups should or desire to play.
15.- Recommendations for actions federal, state local agencies;
the public; labor; trade associations and public interest groups
could have taken or should in the future take to reduce accident
risks.
This reviewer feels that it is relatively unproductive to speculate about
actions that this group of stakeholders might have taken in the past. In
any case the scope of possible actions was limited by practical
difficulties in obtaining concise information on the risk management
programs that existed within facilities and the relative lack resources
available to these groups with the possible exception of trade
associations.
In the future the new EPA rule dealing with the prevention of major
chemical accidental releases should make process safety information and
accident histories much more readily available. This should allow all of
the above entities to do a better job in screening the adequacy of facility
safety programs with the limited resources available to them.
Public interest groups and Federal, State and local agencies could use this
information to make the public aware of the type and magnitude of
facility risks that might affect them. This should lead to an informed
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1 0
public that could chose to directly pressure facilities that they feel have
a less than adequate risk management program and/or generate pressure
to provide resources that would allow agencies to do a more effective job
on their behalf.
Trade, associations could follow the lead of the CMA by making
membership conditional on the implementation of process safety programs
similar those embodied in Responsible Care or generate model safety
programs to assist their members.
Labor unions and Agencies could offer accessible, appropriate process
safety training to employees that do not have adequate training available
through their employer and inform them of the appropriate actions they
might take if less than adequate safety programs exist in their
workplaces.
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11
End Notes
1. Region 7, "Chemical Accident Investigation Report. Terra Industries. Inc. Nitrogen Fertilizer
Facility, Port Neal, Iowa", released 1/23/96.
2. "Settlement Agreement", DIA Docket No. 95 DBS- 20. IOASHA Docket 4446. Citation No.
S7510 - 115072555.
3. "The Terra Port Neal Explosion. December 13, 1994". Report of the Investigation Committee,
July 17, 1995.
4. "Guidelines for Investigating Chemical Processing Incidents", Center for Chemical Process
Safety of the American Institute of Chemical Engineers, N Y City, NY, 1992.
5. The one exception on the conclusions put forward in the EPA Terra Report rests
conditionally on the resolution of questions raised above concerning the role of the sparger.
However even if the Sparger is shown to have played a more significant role in initiating the
explosion in the neutralizer, this would not negate the reasonableness of the six conclusions
put forward
6. "Guidelines for Investigating Chemical Processing Incidents", Center for Chemical Process
Safety of the American Institute of Chemical Engineers, N Y City, NY, 1992, p 8.
7. "MORT Based Root Cause Analysis", EG&G Idaho, Inc., P.O. Box 1625, Idaho Falls. Idaho
83415, June 1989, pp.1 to 3.
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Appendix I
A. Charge to Reviewers
B. Note on Required Deliverables
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CHARGE TO REVIEWERS
For the EPA Chemical Accident Report,
TERRA INDUSTRIES, INC. NITROGEN FERTILIZER FACILITY
EPA Region VII (Kansas City, KS) prepared the above report,
released January 23, 1996, concerning an accident on December 13,
1994 occurring at Terra Industries, Inc. The report is 108
pages long, and includes an executive summary, an overview of the
investigation, discussion of plant operations and events at the
facility, conditions and facts derived by the investigators,
scenarios for the explosion, conclusions and recommendations.
The principal investigators were Mark Thomas of EPA; Alan
Cummings of Dynamac Corporation, an EPA contractor; and Mariano
Gomez, an EPA contractor with its Technical Assistance Team.
As a reviewer of this document, you should use your technical
knowledge and professional judgment to comment on the technical
soundness, overall approach, and completeness of the report, to
derive recommendations for approaches to accident investigations
in the future and accident prevention.
The report seeks to ascertain the root cause of this accident, in
order to further the goal of preventing accidents. Your review
should include the following aspects of this concern.
Comment on the approach taken (scenario by scenario) as a correct
approach to take. Comment on the findings of the report
examining various explosion scenarios, and on the identification
of the most plausible scenario. Were any significant scenarios
missed? Comment on the comprehensiveness and reasonableness of
the statements about technical conditions under which the
accident occurred. Are specific roles of certain equipment,
notably the sparger, appropriately considered?
With no prior history of accidental detonating of AN solution, is
the discussion of the conditions existing before the accident
appropriate? Please comment on the conclusions reached and
whether they lead to the root causes identified.
Were all external factors considered in a comprehensive way?
Also, please comment on whether human factors and broad
management issues were identified appropriately, in appropriate
sequences, in ways to lead to reasonable conclusions and
recommendations.
Please comment on the conclusions and recommendations. What of
the overall approach could be modelled for future such
investigations? Was information for prevention of similar
accidents appropriately presented in this report? Concerning the
role of federal, state local agencies; the public; labor;
trade associations; and public interest groups: please comment
on whether roles of these entities were appropriately addressed.
Are there any recommendations for actions they could have taken,.
or should in future take to reduce accident risks?
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Statement of Work
For Expert Reviewers
Title: Expert Review of EPA Chemical Accident Report, "Terra
Industries, Inc. Nitrogen Fertilizer Facility"
Purpose: The purpose of this statement of work is to provide
external expert review of the above EPA chemical accident
investigation report, including its recommendations and
implications for prevention activities by all parties and future
investigations. The report discusses the cause of an explosion
at the subject facility and presents recommendations to prevent
future similar occurrences.
Background: On December 13, 1994, an explosion occurred in the
ammonium nitrate plant at the Terra International, Inc. complex
in Port Neal, Iowa. Four persons were killed and 18 were injured
as a result of the accident. The explpsion released a large
quantity of anhydrous ammonia to the air, nitric acid to the
ground, and resulted in contamination of the groundwater under
the facility. The EPA report investigating the incident was
developed as part of the Agency's ongoing responsibilities under
the Comprehensive Environmental Response, Compensation, and
Liability Act (CERCLA) and the Clean Air Act, Section 112(r), and
as a component of EPA's chemical safety programs. The report was
released to the public on Tuesday, January 23, 1996 to become a
part of the examination of the causes of chemical accidents and
efforts to prevent them. The report was prepared by staff at
EPA's Region VII office.
As part of its investigative program, EPA desires the review of a
panel of experts who from their individual perspectives and
disciplines can provide comment on the scope, approach and
conclusions of the report and its implications This task is
designed to purchase the services of reviewers for this comment.
Statement of Work: The reviewers will have the following tasks
in accomplishing the objectives of this statement of work (see
companion statement of work for chair):
1. Prior to any meetings, all reviewers will be required to
review and analyze a copy of the subject report.
Each reviewer will prepare written pre-meeting technical
comments on the report, based on the EPA charge and adhering
to the organization and directions of the Chair, a reviewer
so designated by EPA.
Reviewers' written comments are due to EPA, with copies
to the Chair, two weeks prior to a meeting, to be held at
EPA's regional office in Kansas City, KS. The Chair will
distribute copies of all reviewers' comments to all
reviewers prior to a meeting, and organize the meeting.
The Chair will chair this meeting.
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All reviewers will prepare for the meeting by studying
comments prepared by other reviewers. All reviewers may
review or consult any other background documents provided by
EPA or at the direction of the Chair.
2. Attend the two-day review meeting in Kansas City convened by
the Chair to exchange comments and discuss issues raised by the
subject document. Based on the comments and discussions, develop
recommendations to EPA. This meeting is not to be C9nvened for
the purpose of achieving consensus but to exchange views and
comment, expected from the different perspectives of the
reviewers.
Deliverables:
1. Written comment on the subject report.
2. Active participation in exchange of views/ comment at two-day
meeting of reviewers in Kansas City, KS.
Cost Reimbursement Procedures:
The EPA will pay an agreed upon fixed fee to the reviewers. This
fee is intended to cover the reviewers' consulting fee. In
addition, this negotiated fee includes expenses for economy or
excursion airfare, local transportation, miscellaneous and
incidental expenses (i.e. meals), and lodging for two nights at a
ceiling specified in the attached instructions, "Travel
Constraints," that may be required for the reviewers.
To estimate the consulting fee, EPA is estimating that no more
than a total of four days will be required. The total amount of
the agreement will be negotiated by an official from EPA's Office
of Acquisition Management. Once all the deliverables that are
listed above have been provided, the reviewer may submit an
invoice to EPA for reimbursement of a properly justified sum up
to the negotiated amount.
Period of Performance:
Upon award of the contract through September 15, 1996.
Notice Regarding Guidance Provided under this Statement of Work:
The contractor shall not engage in activities of an inherently
governmental nature such as the following:
Formulation of Agency policy
a. Selection of Agency priorities
c. Development of Agency regulations.
Should the contractor receive any instruction from an EPA staff
person that the contractor ascertains to fall into any of these
categories or goes beyond the scope of the contract or work
assignment, the contractor shall immediately contact the Project
Manager or the Contracting Officer.
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Prior to initiation of review, the reviewer shall disclose any
conflict or potential conflict of interest, and shall sign a
conflict of interest/confidentiality form. Forms will be
provided by the EPA project officer. Any COI that surfaces
subsequently during the review process is reported to the project
officer.
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Pg- 59
No procedures for AN TK'
while down.Employees poorly
trained on DCS.Needed pans
not available.
HUMAN
PH Probe defective
PH Probe in line not AN Tk
DCS not operational
No Check or Block valve Nitric Acid
sparger
Back Flow from barometric loop
1. Drain Tk H20 Wash
2. PH to 6 circulate
3. Circulate AN from run down
to Neutralizes
4 DCS operating
5. No steam internal
6. No air purge for long period
of time.
Using plant air to blow Acid
Line into AN Tk not in SOP.
No procedures for steam
sparger.
The major cause of the explosion was no procedures for controlling, monitoring or blow
down of H20 wash of the AN Neutralizer Tk during the time the Tk was down with material in
the tank.
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EPA CHEMICAL ACCIDENT INVESTIGATION
REPORT
TERRA INDUSTRIES, INC
COMMENTS AND QUESTIONS COMPILED BY
JOEL VARIAN
SUBMITTED JULY 15, 1996
PERSPECTIVE: Labor
Hourly Employee
Accident Investigations (Mining)
Accident Investigations (Chemical)
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PLANT BACKGROUND INFORMATION
—PROFILE—
Accident Incident Rate
Lost Time Accidents
Uni on/Non-Uni on
Downsizing? If so, how much & what department?
How much overtime per department?
How many hours?
Is overtime mandatory?
Recordkeeping compare lost time records with state compensation records.
How much contracting of work, normally performed by Terra employees?
Number of excursions reported in last 10 years?
How many inspections by State OSHA EPA, etc. in last 10 years?
How many citations?
What were they?
Routine Maintenance (RM) program in place at the time of the December 13, 1994
explosion in the Ammonium Nitrate Plant?
Request a copy of the Chemical Safety Audit (CSA) recommendations, performed February
1994.
What good faith changes were made by Terra after the Audit?
Ammonium Nitrate sensitization information on page 18 of report - PH, concentration,
tempature, contamination, low density areas are conditions that can sensitize and increase
hazards.
How much of this information did Terra have?
How much was available to them but did not have available to the operators and/or
maintenance department?
The Acid Plant was shut down Dec. 12 at 0430 hours on emergency basis. What was the
nature of the emergency?
Request copy, if available, of the inspection report on the Neutralizer and Nitric Acid sparger
(Sept. 1994).
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OPERATIONAL
—MAINTENANCE-
Procedures, Parts, Inventory, Upkeep Mechanical
On November 27, 1994, Operations and Maintenance personnel determined the PH probe
located in the neutralizer rundown line was defective. There were no spare probes available:
the defective probe was in service until the time of the explosion.
Procedures
AN Neutralizer shut down changed without monitering what was going on in the vessel.
No circulation of a AN vessel during shut down.
The DCS was down - no parts available.
No written SOP on AN Neutralizer while shut down.
No written SOP on checking AN Neutralizer thickness.
Corrosion coil during turnaround.
Steam coils in the Neutralizer jacket had corroded and could not be used for several years.
Parts
What procedure on spare parts was in effect at the time of the explosion?
*should involve metalegists inspection.
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HUMAN
Blowing Nitric Acid line into neutralizer with plant air was not in SOP provided by Terra.
No specific procedure for connecting steam to sparger.
No check or block valve attached to the Nitric Acid sparger where they exit the vessel as per
required by Mississippi Chemical. A Barometric loop that allowed back flow into the
spargers and into the Nitric Acid line back into the barometric loop.
Terra employees stated that the addition of steam was a normal procedure to prevent back
flow into Neutralizer Nitric Acid sparger and to keep the sparger from salting out. Thus,
adding heat to Neutralizer.
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PLANT AIR
The plant air was applied to the Nitric Acid line to purge the line to prevent freezing. The
Nitric Acid was discharged from the line to the AN Neutralizer. The plant air purged the line
from 1500 hrs. until 2030 hrs. 5 Vz hrs. (If my military time is correct) Air and steam was the
last two materials induced into the AN Neutralizer before the explosion.
On page 37: Terra had experienced problems with Hydrocarbons in the plant air.
The Question is: Did the EPA team request piping diagram of the plant air system and if they
received a diagram, were all the precautions necessary to prevent Hydrocarbons from entering
the plant air systems?
Blowing the Nitric Acid line from the acid unit was not in the SOP. Why? What was the
problem using plant air?
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Initial Comments on the USEPA Chemical Accident Investigation Report:
Nitrogen Fertilizer Facility
Terra industries Inc.
Port Neal, Iowa
PAUL L. HILL, Ph.D.
Review Panel Chairman
In undertaking this review I have referenced the "Charge to Reviewers" provided by the contracting
agency, USEPA. Based upon the USEPA Region VTI report released January 23, 1996 concerning
the accident on December 13, 1994, the agency has requested comment on various aspects of their
performance as well as content of the report itself. These include the approach taken; plausibility of
scenarios; technical, human and management considerations related to conclusions; roles of associated
agencies and interest groups and overall recommendations toward a model approach for future
investigations.
As the designated Chairman of the Review Panel, I am charged with conducting a preliminary review
to determine appropriate expertise and diversity of interests for potential reviewers; provide USEPA
with an ample list of potential reviewers; organize the review by collecting preliminary comments and
distributing them among the panelists selected by USEPA; calling a meeting of the panelists to discuss
their reviews of the report; chair said meeting and prepare a written summary of reviewers comments
and recommendations. As a prelude to actual discussions with others my own personal comments
are provided.
Although not charged with reviewing any materials outside the document (written report) itself,
associated materials including Terra Industries' report dated July 17, 1995, Iowa Division of Labor,
Occupational Safety and Health Bureau Inspection No. 115072555 dated May 25, 1995 and
USEPA's supplemental copies of "Drawings and Graphs" were in my possession for reference and
personal review. Because these documents report on the same circumstances (the accident) their
availability is considered appropriate and valuable. Upon this submission no other documents,
evidence or expartate communications have been considered.
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THE CHARGE OF REVIEW
EPA has asked each reviewer, within the limited scope and resources provided, to answer ten
associated questions which roughly correspond to those outlined in paragraph 2 above. In issuing
the charge, EPA has stated that "the reponse seeks to ascertain the root cause of this accident, in order
to further the goal of preventing accidents. Your review should include the following aspects of this
concern."
1. Comment on the approach taken scenario by scenario. ...
This was valuable to the reviewer in ensuring that all plausible avenues of theoretical causality
had been pursued. It was also presented from a physical evidence point of view which helped the
reviewer understand the support for, or lack thereof, of evidence for each potential cause for the actual
explosion. This approach should be replicated in future investigations. If coordinated protocols for
joint accident investigations are achieved, the scenario by scenario approach may be the basis for
closer agreement between vested parties.
2. Comment on the findings of the report and on the identification of the most plausible
scenario.
Findings seem valid. The most plausible scenario is simply the causal theory which generated
the most supportive evidence. In fact much of the chemical, physical and spatial evidence collected
by other assessments supports that of the EPA's most plausible scenarios. While there are no
unequivocal answers to lingering questions about contamination sources, titaniumions, chlorides, etc.
as discussed by the less plausible scenarios, the conclusions reached by the report are reasonable.
3. Comment on the comprehensiveness and reasonableness of rhe statements about technical
conditions under which the accident occurred.
This position of the report is supported by known AN chemistry principles, historical
production and laboratory tests. All parties who expressed views on the technical conditions in the
neutralizer, rundown tank, etc. are closely aligned with few exceptions. The report does a good job
at putting this information forward in the discussion but takes the added approach of "scenario
building" through which the reviewer can actually pursue technical conditions in light of physical
evidence.
4. Are specific roles of certain equipment, notably the sparger, appropriately considered?
A degree of uncertainty exists here. The report dismissed most of the theories about the
sparger and titaniumions rather readily as compared to the contentions of likely cause presented by
other parties. Further pursuit by the review team is needed to properly address the basis for this
disparity Due to the limited scope of this review, it is also recommended that EPA continue research
and discussions with technically competent and affected parties to resolve discrepancies in either
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theory or evidence.
5. Is the discussion of AN solution appropriate?
Generally, yes. Introductory, theoretical,, chemical, technical and operational background on
AN solution properties, management and handling were appropriate for the discussion: Suggest this
kind of literature search for state-of-the-science become a standard fixture for well prepared,
comprehensive reports. (Up through section 6). Continued monitoring of AN production and
research literature is properly noted but perhaps should be more emphasized or gathered and
circulated by the fertilizer industry, associated agencies, other?
6. Were all external factors considered in a comprehensive way? And, were human and
management factors identified in such a way as to lead to reasonable conclusions and
recommendations?
The report does not provide a surplus of details about the investigation team's interaction with
management or the depositions of hourly employees. Obvious however, is the lack of, or inability
to produce, procedures, instructions and training logs or PID's for the proper understanding of the
operation and therefore the ability to operate it safely. When coupled with the physical and chemical
evidence, human factors, as presented, lead one to the conclusions and recommendations as presented
in sections 9 & 10 of the report.
7. Comment on the overall conclusions and recommendations. What of the overall approach
could be modeled for future investigations?
Readability and sequence of information lay-out are generally good. However, information
on page 33, 34 could be developed into standard time-line information to gain graphic illustration of
events. For plausibility and causality, the scenario by scenario approach is very good. This provides
the reviewer with the investigation team's "thinking" and second guesses as they attempted to
reconstruct conditions of the accident. Successfully eliminating scenarios based on the evidence
ensures the reviewer that other theories of causality were investigated. However, not all potential
scenarios were presented. See Additional Questions & Comments.
8. Was information for the prevention of similar accidents appropriately presented in this
report?
Although presented clearly within the report itself, it is unclear how EPA or other agencies
may convey, in an ongoing fashion, results and recommendations of this nature. Industry-wide
advisories, special notices to the fertilizer industry, etc. should be considered. Special bulletins and
advisories similar to those of NTSB should be issued in the interests of all facilities, workers and
potentially affected parties. Currently, within the report, it is unclear that such parties will receive
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this information
9. Comment on whether the roles of other entities were appropriately addressed
It is difficult to determine how the needs, if any, of other entities have been addressed by this
report since there was no coordinated effort which involved all the parties in the actual investigation.
Iowa has a designated "State OSHA" authorization from the federal agency therefore making this
particular investigation even more disjunct than might have otherwise been possible. If coordinated
investigations and joint reports are to be achieved as envisioned by the CAAA of 1990, then a broad
protocol, clearly defining roles of all interested entities must be developed and codified.
10. Are there any recommendations for actions that could have been taken or should in the
future take to reduce accident risks?
The agencies, both EPA and OSHA as well as state program officials should follow-up with
AN producers regarding the extensive recommendations provided by this report. The agencies should
also continue to monitor from an R&D prospective, the use of titanium materials as presented by the
Terra review. Both reports strongly agree that proper procedures, training and monitoring must be
continuosly in place for proper prevention to occur
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ADDITIONAL QUESTIONS & COMMENTS
Did EPA compile any emergency response documentation of this case and integrate it with
the findings for consumption by all parties, particularly lay public?
While this in an accident investigation report it provides an opportunity for other EPA
sponsored initiatives.
Is this, or will it be, addressed elsewhere?
Is there ongoing review or reconsideration of the metallurgists' findings?
Much of the evidence for direction, impact of physical damage, etc. rests on this report
Is EPA reviewing?
Was sampling adequate given the suggestion by Terra that small isolated areas may have
initiated deflagration?
Chlorides and "low density areas" were noted as potentially plausible factors on page 36 and
38 of the report but were later dismissed as the initiating factor.
Could this be due to lack of samples from various sites?
How much collective data was reviewed by the investigative team to reach this decision?
What about additional evidence (e.g.pump) which was never recovered?
Might there be other significant evidence which supports other theories? (e.g. the initiation
occurred in the sparger).
Was the entire sparger (all pieces) recovered so as to completely eliminate the concept of
"isolated site initiation"?
Sabotage. This was not dealt with. Why?
If, via the depositions of parties, this (theory) was successfully eliminated then it should be
stated in the report.
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EPILOGUE
First, accident investigations and the attempt to reconstruct the conditions which led to
accidents are inherently difficult to pursue. The report indicates in its introduction that certain
evidence, diagrams and requested documents were either destroyed or unavailable for this
investigation report. Even with satisfactory provisions of existing management, operations and
training materials, reliance upon human knowledge and recollections as well as potential
nondisclosure makes the job of reconstruction all the more difficult.
Although not only pertinent to this review, the investigating agency needs to clearly define
its investigative approach to future investigations from a purely professional/scientific view. If called
into question (most contentious reports are likely to be litigated) the agency (s) needs to simply
describe their command of the existing literature on investigative techniques and which of these they
either chose to use, modify for use or discard as inappropriate, given the particular investigation.
Many such technical approaches also have the added advantage of providing the reader or reviewer
with a graphic representation of the approach (e.g. fault tree), as well as the technique or
combinations of techniques used to approach the investigation process. CCPS's "Guidelines for
Investigating Chemical Process Incidents" copyright 1992 provides at least one good example of
various inductive, deductive, morphological and non-systems techniques for accident investigation.
While I have responded to the agency's needs to the best of my abilities, at this time, I reserve
the right to respond further after seeking the advice and considerable expertise of my colleagues.
Therefore these comments are subject to modification after the discussions in Kansas City.
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APPENDIX
III
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Addendum to Renew of EPA
Chemical Investigation Report
Tern Industries, Inc.
By
AuncfeNkra
This •AUnAim a to fulfill my charge u reviewer.
1. Comment on the approach taken (scenario by scenario) as a comet approach to take.
The scenario* regarding plausible cauae(s) of the erosions appear to be weH thought oat
However. I can not comment as to whether any significant scenarios were missed.
NOTE: On page 1 of my original report, pkase disregard the first boDet that began as
follows: Tetroiemn tpffl in the ammonia plant-." - the EPA investigation had eliminated
it as being a potable contributing factor.
2 With no prior history of accidental detonation of AN solution, is die ruVutrion of the conditions
f U'ffr^i otfint the acfiofnt afijjiUjJUttlfc
This reviewer believes that the discussion of the conditions was necessary to give the review-
er* a description of the process operations leading op to the explosions.
3. Please comment an the conclusions reached and whether they lead to the root causes identified.
This reviewer believes that one or aH of the conditions that existed in the neutrafaer just
prior to the explosions could have caused the event of December 13, 1994.
• The strongly acid condition* in the nentnfizer
• The application of 200 prig steam to the nitric acid spargers and the superheat that
possibly reached the nentnlizer
* The application of compressed air which created low density zones in the AN solution
• Lack of ftowm the neutrahzer and from the neutndiz^
isolated critical sensors
• Chtorides contamination in thc nitric acid and «n»^n<\nimn nitrate
• Lack of monitoring of the AN plant when in shut down
In this reviewers opinion, the primary cause of die > 2 explosions was the lack of a process safety
mmiagfim rm system which should have inrtnrlrd safe operating procedures, a hazard communication
program, and process hazard analyses of the different units/plants within the facility.
If a safety management system had been in place, the employees would have known how to safely
shut-down and start-up the process. The employees abo would have known the risks and potential
consequences involved in performing impiuper procedures. The FHA would have identified critical
areas in the process that needed modifications to minimize or manage the type of incident that
occurred at Terra.
4. Were all external factors countered in cmnpnhcnm*:
This reviewer has no way of measuring whether afi external factors were considered. This
question is outside my field of expertise.
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5. What of the ovtr ell approach could have beat modelled Jbr future such mvstiffitions?
The over an approach which oouki be modelled for future investigations should include the
following:
' Diagrams and photos (especially aerial photos) of the faculty before the event, and
*fter the rnrH^ir* to show the direction and magnitude of the event
' Development of scenarios using historical data and the evidence found following the
dplonoos
• The use of opera, such as metallurgists, and other professionals knowledgeable of
tiie partifnbrr process.
This reviewer rfer>m
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Addendum to Report of Geraldine V. Cox on Terra Report.
Dated August 5, 1996
After further discussions with chemists familiar with Ammonium Nitrate and the meeting of the reviewers
in Kansas City last week, I would like this addendum to be attached to my initial report.
1. Sensitizer(s). Clearly something or multiple chemical compounds acted to sensitize the reaction.
EPA believes that the chloride ion may be the sensitizer. After review of the limited chemical data
presented in the Terra report two other, equally plausible materials could have acted as sensitizers,
either alone or in combination with each other or with chloride. These additional sensitizers are
chromium and iron (ferrous and ferric complex). Both could have been formed from the metal in the
neutralizer tank, especially after the prolonged contact with very low pH, e.g., 0.8. The metallurgist's
report indicated pitting on the walls of the stainless steel tank. This pitting is an additional indication
that solution of the stainless steel reaction vessel probably occurred. The values of the chromium and
iron in the AN storage tank indicated the presence of all three elements. I doubt that the sensitizer
will ever be defined at this point, but three candidates were present in the finished product, so any of
these could have contributed. The limited data do not seem to have sufficient concentrations of oil
to make that a likely contributor to the sensitizing process.
2. After reviewing the original photographs of the site before and after the event, the probable chain of
events is even more compelling. The EPA report seems to provide the most plausible sequence of
events, i.e., that the reaction began in the middle of the neutralizer and then the run down tank had a
secondary explosion.
3. The actual incident may never be fully defined. However, the conditions were present - namely
heat, sensitizers, low pH, and bubbles that all contributed to the event. The absence of written
procedures for shut down and the warnings for unsafe operating conditions, i.e., documented
procedures and training for the workers clearly allowed the development of these critical conditions
for the event.
4. More chemical analysis of the residues in the tank and at the site would have been helpful to
understand the chemistry, but, since the State Fire Marshall hosed the site with water, I am not sure
how useful samples would have been after that contamination from the fire hose.
5. While we were not asked to review the report prepared by Terra, the chemical analysis were of some
use. The table was not identified as well as it might have been, for example, the sources of the two
water analyses. In particular, the sodium value for the water aid not match for the two water samples
in the Terra Table. (Also, there was no indication of replicates, deviations of the values for replicates,
and the instrumentation and methods used for the analyses.) This high sodium value might be an
indication of high chloride concentration, although a chloride analysis was not provided for the water.
The variation for chromium and iron are interesting for the various sources and do indicate a higher
level than I would have expected for such a process.
6. Clearly the first responsibility when responding to a chemical accident, such as this, will be to
stabilize the site to mitigate harm to the plant, community and environment. Yet, at the same time,
one must begin to approach such events from a forensic perspective. If such an event were sabotage.
which I do not believe this incident was, one would want to protect the site until a criminal
investigation could be conducted. Therefore, I think that EPA needs to consider how to secure the
site for such an investigation during and immediately following the incident, This is easy to say, but
more difficult to do - especially with various jurisdictions all having some authority at the site from
the plant personnel to the multiplicity of local state and federal agencies with a legitimate role at the
site. Perhaps discussions with the National Transportation and Safety Board might be useful to
determine how they would handle such a situation. Do they have prearranged agreements and
procedures that might be used?
7. In future incidents, a review of the reported accidents and injuries and a comparison with worker
compensation claims would be a good indication of the ongoing safety record at any plant under
review. This might be made a normal part of the incident report.
8. EPA needs a better definition of its role relative to state OSHAs. This might require legislative
change since state primacy is a legislative initiative. In serious chemical accidents where the
W)6 0 2 1996
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surrounding community could be endangered, the normal state or federal OSHA review might not be
adequate.
9. Several typographical errors appear in the original report. The most significant is on page 2, in the
last paragraph on the page, 4th line. The word "absent" should be replaced by the word "present."
Other corrections are: Same paragraph on page 2: second line Since the pH sensors was; page 5,
1st full paragraph, third line first word, system?; same page, item 7, 7th line of response, should read:
"period, although, . . "; page 6, 1st paragraph of response, 4th line ". . . report of the depth of the one
prepared bv EPA."
Submitted 7th August 1996,
Geraldine V. Cox, Ph.D.
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EPA Response to Expert Review Recommendations
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EPA Response to Expert Review of
EPA Investigative Report on Terra
RECOMMENDATION: EPA should include time lines in future reports.
REPLY: EPA agrees that this element would enhance future reports and is explicitly
including it in the EPA/OSHA joint protocol on investigations, now being prepared.
RECOMMENDATION: EPA should expand and continue to model the scenario-by-scenario
approach.
REPLY: EPA has included this as well in the proposed protocol. We would expect
that the approach will become more and more refined as the program matures. This is a
valuable tool for those investigations when this approach is appropriate. Reports should
include a full discussion of scenarios discarded as well as considered.
RECOMMENDATION: EPA should adopt or specify rigorous technical procedures
sanctioned by the engineering and research communities.
REPLY: EPA is aware of the available established methodologies for accident
investigation. Its investigators will receive training on several of these procedures. The EPA
investigation team will choose one or more of these procedures for a given investigation and
will describe the investigative methodology in its report.
RECOMMENDATION: EPA should develop a refined protocol for accident investigations.
REPLY: EPA agrees that such a protocol is necessary and has been developing a joint
protocol with OSHA during the past year. This protocol defines the purpose and goal of
investigations; spells out cooperation among EPA, OSHA, local investigators, and local
stakeholders; includes discussion of technical approaches and procedures for conducting
various elements of investigations; addresses protection of confidential business information;
and addresses production of the accident report and alerts which may stem from information
gathered during the investigation. This will be a public document which will inform all of
the investigative program.
RECOMMENDATION: EPA should hold public meetings to seek stakeholders' input on the
protocol.
REPLY: EPA plans to share the proposed protocol with stakeholders who will be
potentially affected by investigations conducted according to its directives. To obtain these
comments, we will make the draft protocol available through electronic and other means and
will consider actions such as holding a public meeting as recommended. We expect that the
protocol will be revised periodically as needed.
RECOMMENDATIONS: EPA should consider accident oversight committees at affected
sites which include public liaisons.
REPLY: EPA agrees that vehicles should be available for public input into and
communication with the review team. Existing elements such as Local Emergency Planning
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Committees could serve this function.
RECOMMENDATION: EPA should initiate agreements with other federal, state, and local
entities with accident response authorities or consider legislative recommendations to
accomplish same.
REPLY: We agree such agreements are essential. EPA and OSHA have been
developing a Memorandum of Understanding to set forth terms of cooperation and
coordination between the agencies, to ensure the most effective investigations and to avoid
duplication of effort. EPA has initiated efforts to establish agreements with State OSHAs.
We are investigating means to coordinate with other entities such as State Emergency
Response Commissions (SERCs) and State Fire Marshals.
RECOMMENDATION: EPA should create increased public and private awareness of its
investigative program.
REPLY: EPA has already presented its accident investigation program at numerous
national public conferences and state workshops during the last year. We are developing an
outreach program to share results of investigations to all stakeholders and to alert them to
particular hazards identified in the course of investigations. This activity will assist in making
the program known and can be the occasion for working with particular industries or trade
associations about specific hazards defined after an accident. We are preparing such an alert
for ammonium nitrate facilities, which will be of use not only to the affected industry but also
to communities having such facilities nearby. We can build on our existing work with
professional societies like the American Institute of Chemical Engineers (AIChE) Center for
Chemical Process Safety (CCPS) and others, as well as trade associations, with whom we
have worked on aspects of the chemical accident provisions of the Clean Air Act
Amendments. We have begun developing fact sheets and will continue to explore other
vehicles and opportunities for outreach.
RECOMMENDATION: EPA should clearly articulate the national goals and criteria for
accident investigation.
REPLY: We agree that this is important to the integrity and acceptance of our
investigations. We will include this element explicitly in the outreach activities noted above,
as well as in our agreements with federal, state and local entities with whom we will work in
particular investigations. As noted above, our protocol for investigations can serve this
purpose as well, as it will include discussion of goals and objectives of investigations; an
explanation of EPA and OSHA authorities; and procedural steps for the conduct of
investigations. The document will be available to the public and to all stakeholders.
RECOMMENDATION: EPA should draw upon the existing experience of NTSB and
other agencies for assistance in the evolving program.
REPLY: We are drawing upon the experiences of the National Transportation
Safety Board (NTSB), the Bureau of Alcohol, Tobacco and Fire Arms (BATF), OSHA, and
the National Institute of Standards and Technology (NIST) in accident investigation in
developing draft protocols and training for our investigators. We will continue to work
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closely with these agencies and others. We also can access expertise from the National
Response Team, a coordinating body of 15 federal agencies having responsibilities for various
aspects of dealing with hazardous materials. It should be noted that we are working with
these agencies and others to assemble ways to obtain expert assistance for very specific
expertise which may be needed in the course of a particular accident investigation.
Additional notes and recommendations:
The expert reviewers of EPA's report, in addition to articulating the above recommendations
for EPA in their summary, commented on a number of specific issues concerning the Terra
Industries investigation and included additional recommendations in the text of their report:
ROLE OF THE SPARGER:
One issue is the particular role of the sparger in the accident at Terra Industries. To date,
EPA has not received any additional evidence or scientific data that would lead to altering any
findings, conclusions, or recommendations in the final report.
IDENTIFICATION OF ROOT CAUSES: Another issue raised by the reviewers was that
EPA should provide more attention to the relationships between root causes and conclusions
in the report. That is, the conclusions themselves were less explanatory of root cause than
was the body of the discussion of the report. EPA acknowledges that some root causes
should have been better explained in the conclusion section of the report. In future accident
investigation reports, EPA will provide better identification and summary of root causes of the
accident as well as correlating the root causes with the recommendations. In addition, EPA
provided in the Terra report general recommendations to the ammonia fertilizer industry as a
whole to prevent conditions such as those existing at Terra from recurring.
NATIONAL NETWORK OF INVESTIGATIVE CAPABILITIES:
The reviewers noted that EPA should consider a national network of investigative capabilities
and expertise as its accident investigation program matures, and should include in the network
integrating the use of personnel or contract services with particular expertise and should also
include the expertise of OSHA, states, etc. The joint EPA/OSHA investigation protocol now
being prepared notes that EPA has a contract in place to provide technical assistance for
accident investigations. This contract also allows EPA to access, as needed, experts in various
technical fields to assist in information gathering and analysis. In addition, EPA is
developing a list of available EPA regional staff and contactors with their expertise whom
EPA could rely upon for assistance in investigations. As noted above in a reply to a related
recommendation, EPA can also utilize capabilities of other federal agencies, for example the
testing and analysis laboratories of NTSB, NIST, and EPA. EPA and OSHA will also solicit
the expertise of other Federal agencies, for example, BATF, NTSB, DOD, and DOE.
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APPENDIX A
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CHARGE TO REVIEWERS
For the EPA Chemical Accident Report,
TERRA INDUSTRIES, INC. NITROGEN FERTILIZER FACILITY
EPA Region VII (Kansas City, KS) prepared the above report,
released January 23, 1996, concerning an accident on December 13,
1994 occurring at Terra Industries, Inc. The report is 108
pages long, and includes an executive summary, an overview of the
investigation, discussion of plant operations and events at the
facility, conditions and facts derived by the investigators,
scenarios for the explosion, conclusions and recommendations.
The principal investigators were Mark Thomas of EPA; Alan
Cummings of Dynamac Corporation, an EPA contractor; anc^ Mariano
Gomez, an EPA contractor with its Technical Assistance Team.
As a reviewer of this document, you should use your technical
knowledge and professional judgment to comment on the technical
soundness, overall approach, and completeness of the report, to
derive recommendations for approaches to accident investigations
in the future and accident prevention.
The report seeks to ascertain the root cause of this accident, in
order to further the goal of preventing accidents. Your review
should include the following aspects of this concern.
Comment on the approach taken (scenario by scenario) as a correct
approach to take. Comment on the findings of the report
examining various explosion scenarios, and on the identification
of the most plausible scenario. Were any significant scenarios
missed? Comment on the comprehensiveness and reasonableness of
the statements about technical conditions under which the
accident occurred. Are specific roles of certain equipment,
notably the sparger, appropriately considered?
With no prior history of accidental detonating of AN solution, is
the discussion of the conditions existing before the accident
appropriate? Please comment on the conclusions reached and
whether they lead to the root causes identified.
Were all external factors considered in a comprehensive way?
Also, please comment on whether human factors and broad
management issues were identified appropriately, in appropriate
sequences, in ways to lead to reasonable conclusions and
recommendations.
Please comment on the conclusions and recommendations. What of
the overall approach could be modelled for future such
investigations? Was information for prevention of similar
accidents appropriately presented in this report? Concerning the
role of federal, state local agencies; the public; labor;
trade associations; and public interest groups: please comment
on whether roles of these entities were appropriately addressed.
Are there any recommendations for actions they could have taken,
or should in future take to reduce accident risks?
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