large-scale explosion consequence modeling west, texas fertilizer plant case study

Modeling Software for EH&S Professionals

Large-Scale Explosion Consequence Modeling: West, Texas Fertilizer Plant Case Study

Prepared By:

Brian Holland – Senior Scientific Specialist/Meteorologist Stephen Koch – Senior Software Developer

Qiguo Jing, PhD – Senior Software Developer/Consultant Weiping Dai, PhD, PE, CM - Director of BREEZE Software and China Operations

BREEZE SOFTWARE 12700 Park Central

Drive, Suite 2100 Dallas, TX 75251

+1 (972) 661-8881 breeze-software.com

October 28, 2014

Trinity Consultants | LARGE-SCALE EXPLOSION CONSEQUENCE MODELING 1

Abstract

The West, Texas Fertilizer Company plant explosion on April 17, 2013 has highlighted the

number of similar facilities whose potential hazards had been previously overlooked in part due

to limited government and small-industry resources. This paper presents a preliminary case

study of the event using BREEZE ExDAM (Explosion Damage/Injury Assessment Model), and

examines the utility of such a model for quantifying these overlooked hazards.

BREEZE ExDAM is a software tool designed to perform explosion consequence modeling

(ECM) using a phenomenological approach which is computationally more sophisticated than

simple blast radius methods and computationally less sophisticated than physical modeling

methods (e.g. CFD). Damage/injury levels of different structure/people types are derived from

structure material properties and peak incident pressures/impulses adjusted for shielding effects

using a dipole flow-field algorithm. Such a tool might provide cost-sensitive local governments

and smaller industrial facilities with a comparatively simple but meaningful tool for assessing the

risks posed by a West-style incident.

The methodology used in this case study, to quantify peak incident pressures and subsequent

damage/injury levels while accounting for different structural materials and shielding effects, is

discussed. Predicted damage/injury patterns are compared to publicly-available information.

The particular strengths and weaknesses of the ExDAM model are discussed and compared to

CFD models.

Introduction

On April 22, 2014, more than one year after the April 17, 2013 West Fertilizer Company plant

explosion in West, Texas, the Chemical Safety Board (CSB) presented its “preliminary findings”

[1, 2] which included the following observations (bold emphasis ours):

1. “14 fatalities, 226 injuries, and widespread community damage.”

2. “We found 1,351 facilities across the country that store ammonium nitrate

[AN]. Farm communities are just starting to collect data on how close homes or schools

are to AN storage, but there can be little doubt that West is not alone and that other

communities should act to determine what hazards might exist in proximity.”

3. “The investigation notes other AN explosions have occurred, causing widespread

devastation. A 2001 explosion in France caused 31 fatalities, 2500 injuries and

widespread community damage. In the United States, a 1994 incident caused 4 fatalities

and eighteen injuries. More recently a July 2009 AN fire in Bryan, Texas, led to an

evacuation of tens of thousands of residents. Fortunately no explosion occurred in the

Bryan, Texas, incident which highlights the unpredictable nature of AN.”

4. “The CSB’s investigation determined that lessons learned during emergency responses to

AN incidents – in which firefighters perished -- have not been effectively disseminated

to firefighters and emergency responders in other communities where AN is stored and

utilized.”


5. “The CSB has found that on April 17, 2013, West volunteer firefighters were not

aware of the explosion hazard from the AN stored at West Fertilizer”.

6. “At the county level, McLennan County’s local emergency planning committee did not

have an emergency response plan for West Fertilizer as it might have done under the

federal Emergency Planning and Community Right to Know Act. The community

clearly was not aware of the potential hazard at West Fertilizer.”

7. “The Chairperson called on states and counties across the country to take action in

identifying hazards and requiring the safe storage and handling of ammonium nitrate.”

In its earlier June 27, 2013 “Written Senate Testimony” [3] the CSB made additional

observations (bold emphasis ours):

1. “The ammonium nitrate, a granular solid, was stored in the facility’s fertilizer warehouse

building in wood-framed bins with wooden walls. Both the warehouse building and the

bins were constructed of combustible wooden material, and the building also

contained significant quantities of combustible materials such as seeds stored near the

bins of ammonium nitrate.”

2. “Over time, many residences, a nursing home, an apartment complex, a high school,

and an intermediate school were constructed within a 2000-foot radius of West

Fertilizer.”

3. “Although the firefighters were aware of the hazard from the tanks of anhydrous

ammonia as a result of previous releases, they were not informed of the explosion

hazard from the approximately 60 tons of fertilizer grade ammonium nitrate inside

the warehouse.”

4. “Residents of the West Rest Haven nursing home were severely affected, and according

to nursing home officials 14 patients have passed away since the April 17 explosion,

dying at twice the expected rate. The nursing home itself was destroyed, as was the

apartment complex across the street. Two large schools – the high school and the

intermediate school – were structurally damaged beyond repair and will be torn down,

and a third school was also badly damaged. Because of the hour of day, all the schools

were unoccupied. Had the explosion taken place during the day, severe casualties

could have occurred in the intermediate school, which was devastated by both blast

and fire. Post-explosion damage assessments indicate that it would have been difficult for

children and others to escape from the building. The CSB is currently evaluating the

vulnerability of this structure, to understand the potential consequences if the

explosion had occurred when children were present and to inform future siting

decisions.”

5. “Nearly 200 homes were severely damaged or destroyed, a sizeable fraction of all the

houses in West. Financial damage is still being assessed, but the cost to rebuild the

schools alone will reportedly approach $100 million. Some reports suggest total

damages to the town may exceed $230 million, an unimaginable blow to a town of just

2800 residents – more than $80,000 for each man, woman, and child living in West.”


6. “Ammonium nitrate has historically been involved in some of the most severe chemical

accidents of the past century, including disastrous explosions in the United States,

Germany, and France. Two of these accidents – in Oppau, Germany, in 1921 and in

Texas City, Texas, in 1947 – each killed 500 or more people.”

7. “In September 2001, for example, a large AN explosion occurred at a factory in

Toulouse, France, killing 30, injuring thousands of others, and damaging up to

30,000 buildings.”

8. “The explosion at West Fertilizer resulted from an intense fire in a wooden warehouse

building that led to the detonation of approximately 30 tons of AN stored inside in

wooden bins.”

9. “Although some U.S. distributors have constructed fire-resistant concrete structures for

storing AN, fertilizer industry officials have reported to the CSB that wooden buildings

are still the norm for the distribution of AN fertilizer across the U.S.”

10. “No federal, state, or local standards have been identified that restrict the siting of

ammonium nitrate storage facilities in the vicinity of homes, schools, businesses, and

health care facilities. In West, Texas, there were hundreds of such buildings within a

mile radius, which were exposed to serious or life-threatening hazards when the

explosion occurred on April 17.”

11. “West reported the presence of up to 270 tons of ammonium nitrate, as well as

anhydrous ammonia, at the site. The company did not provide the LEPC or the West

Fire Department with an ammonium nitrate MSDS indicating the material’s

hazards, nor does EPCRA automatically require that information to be provided.”

12. “Combustible wooden buildings and storage bins are permitted for storing AN

across the U.S. – exposing AN to the threat of fire. Sprinklers are generally not required

unless very large quantities of AN are being stored or fire authorities order sprinklers to

be installed. Federal, state, and local rules do not prohibit the siting of AN storage

near homes and other vulnerable facilities such as schools and hospitals.”

On August 1, 2013, in response to these and many other issues, President Obama issued

Executive Order (EO) 13650 - Improving Chemical Facility Safety and Security [4].

Subsequently, in May 2014, the EO-established Chemical Facility Safety and Security Working

Group, tri-chaired by the EPA, DOL, and DHS, released its first “Report to the President” [5]

stating in their initial “Message from the Working Group Tri-Chairs” (bold emphasis ours):

“The Working Group, its member agencies [EPA, DOL, DHS, DOJ, DOA, DOT], and

the broader community of stakeholders have practices, operations, protocols, and policies

that address chemical facility safety and security but all recognize that improvement is

necessary and requires a shared commitment from all stakeholders. Emergency

responders, in particular, have needs to be addressed and capabilities to be

strengthened so that they can better manage threats and hazards in their

communities.”

Considering the ‘current events’ presented above, there is a fundamental need, directly within the

emergency responder community and their local supporting agencies, to not only ‘identify’ but to


quickly and accurately ‘quantify’ the life and economic consequences of potential explosions.

There are numerous software tools available for predicting human injury and structural damage.

However, most of these tools require prohibitively extensive human expertise, computing

resources, and project development/processing time.

This paper first briefly describes the ExDAM/HExDAM (High Explosive Damage/Injury

Assessment Model), a comparatively simple less-resource-intensive method for explosion

consequence modeling, and then demonstrates how the model can be used to quickly and

accurately replicate, analyze and predict the consequences of the West, Texas event.

Most generally, the objectives of this paper are two-fold:

1. Propose and demonstrate an alternative approach for addressing some of the CSB’s

suggestions regarding the West, Texas event (highlighted above):

a. Provide tools to “take action in identifying hazards”.

b. Quantify, analyze, prepare for, and mitigate potential consequences: “fatalities”,

“injuries”, and “widespread community [financial] damage” (e.g. “1,351 facilities

across the country that store ammonium nitrate”, some or most with “wooden

buildings” and some or most “in the vicinity of homes, schools, businesses, and

health care facilities”).

c. Help “firefighters [be] aware of the explosion hazard”.

d. Provide tools to “effectively disseminate [lessons learned] to firefighters and

emergency responders in other communities where AN is stored and utilized”.

e. Help “the community [be] aware of the potential hazard” and the “local

emergency planning committee [prepare] an emergency response plan”.

f. Determine whether “severe casualties could have occurred in the intermediate

school” “had the explosion taken place during the day”.

g. Provide tools for “evaluating the vulnerability of [the intermediate school], to

understand the potential consequences if the explosion had occurred when

children were present and to inform future siting decisions.”

2. Solicit cooperation from government, industry, and academia to evaluate and further

develop ExDAM’s phenomenological approach for providing a practical (i.e. simple, fast,

and accurate) solution for a variety of conventional explosion safety/security-related

problems such as:

a. Explosion Consequence Analysis (ECA)

b. Emergency Response Planning (ERP)

c. Event Reconstruction and Forensics Analysis

d. Consequence Mitigation Design & Testing

e. Event/Facility Planning & Security

f. Facility Siting Analysis & Regulatory Compliance

g. Overpressure Exceedance Analysis (OEA)

h. Quantitative Risk Assessments (QRA)

i. Security and Vulnerability Assessments

j. Force Protection Modeling, Simulation and Analysis

k. Perimeter Analysis (Standoff Distance Determination)


Large-Scale Explosion Modeling with BREEZE ExDAM

The modeling of large-scale explosions, involving numerous/complex structures and numerous

gathered/dispersed people, is a daunting challenge. In most cases, the primary objective is to

predict the distribution of structure damage and human injury due to one or more explosions.

Damage levels are typically reported in four categorized: no damage, slight damage (useable,

requiring minor repairs), moderate damage (partially usable or temporarily unusable, requiring

major repairs), and severe damage (permanently unusable, irreparable). Injury levels are

typically reported in six categories: no injury, walking wounded, needs minor surgery, seriously

injured requiring major surgery, unlikely to reach hospital alive, and deceased.

Computationally, local damage and injury levels are a function of incident pressures and

impulses which are a function of the blast wave/energy passing through air, reflecting off less

damaged structures, and passing through more damaged structures. CFD modeling methods

simulate these physical processes over time and space. Unfortunately, for large-scale projects

with limited resources CFD modeling can be prohibitively expensive. However, for complex

structure scenarios, any alternative modeling method must provide a mechanism to compute

incident pressures/impulses due to blast waves passing around and through structures.

ExDAM’s explosion models, HExDAM and VExDAM (Vapor Cloud Explosion Damage/Injury

Assessment Model), provide this mechanism using a unique ‘shielding’ algorithm which acts to

reduce incident pressures/impulses behind shielding structures using a dipole-flow-field

distribution.

To facilitate this shielding algorithm, ExDAM structures (See Figures 1, 2) are composed

exclusively of ‘blocks’. Complex block structures can be quickly created within ExDAM’s 3D

window using an extensive set of basic block editing operations (e.g. cut, stretch, copy, rotate,

translate) and advanced shape editing functions (e.g. extrude/interpolate/extrapolate,

cylinder/sphere, building with walls/floor/ceiling/windows/people). Structure editing is further

facilitated with options to import images (e.g. satellite images, floor planes, building profiles),

import 2D/3D line/surface models (e.g. CAD data, Google 3D Buildings), and import any

number of structures from other ExDAM projects recursively (e.g. urban scenario project…

imports parking garage project… which imports numerous car/truck projects).

Figure 1. ExDAM UI with Example Block Structures

Figure 2. Structure with Floor Plan

Structure blocks are each assigned a material. Derived from empirical (i.e. observed

phenomenological) data, ExDAM’s structure materials directly correlate incident


pressures/impulses to percent damage/injury values with default damage/injury thresholds of

slight/moderate/severe set at 5%, 30%, and 75%, respectively. Material selection is quite simple

for macro-level analyses (i.e. modeling structures located large distances from blasts). However,

material selection can become critically important and relatively more complicated for projects

requiring micro-level analyses (i.e. modeling complex structures in close proximity to blasts).

Examples of whole-structure materials include:

a. Multistory Reinforced Concrete Bldg With Concrete Walls

b. Multistory Steel-Frame Office, Earthquake Resistant

c. Bldg W/ Med Weight Pre-Eng. Metal, Ltwt Walls & Roof

d. Bldg W/ Tilt-Up Concrete Wall, Lightweight Roof

e. Bldg W/ Reinf Concrete, 25 Cm. Walls, Reinf Concrete Roof

f. Bldg W/ Reinforced Masonry, 20 Cm. Walls, Light Roof

g. Ind Bldg W/ Heavy Frame (St Or Con), Unreinf Masonry Walls

h. Res Bldg W/ Wood/Steel Stud Wall, Ltwt Joist Or Truss Roof

i. Res Bldg W/ Multistory Wall-Bearing, Brick Apt House

j. Res Bldg W/ Wood Frame, House Type

Examples of structure component materials include:

a. Brick Wall Panel, 20 Or 30 Cm., Non-Reinforced

b. Concrete Or Cinder-Block Wall Panels, Non-Reinforced

c. Glass Windows, Large And Small

d. Steel (Corrugated) Paneling

e. Wood Siding Panels, Standard House Construction

When explosions are located close to buildings, such that the incident blast pressures/impulses

passing across the structure vary significantly, complex structure geometries composed of

numerous component blocks (e.g. column, beam, wall panel, floor panel, door, window) are

typically created and assigned a variety of different materials. For this type of ‘micro-level’

damage assessment, structure materials (i.e. structure vulnerability parameters) can be derived

directly from pressure/impulse (PI) data. For example, ExDAM structure vulnerability

parameters can be generated from VASDIP (Vulnerability Assessment of Structurally Damaging

Impulses and Pressures) [6] pressure/impulse (PI) data which includes a variety of structure

component types such as:

a. Reinforced Concrete Beams

b. One/Two-Way Reinforced Concrete Slabs

c. Reinforced Concrete Exterior Columns (Bending)

d. Reinforced Concrete Interior Columns (Buckling)

e. Reinforced Concrete Moment-Resisting Frames

f. Steel Beams

g. Metal Stud Walls

h. Open Web Steel Joists (Tension Failure in Bottom Chord)

i. Open Web Steel Joists (Web Buckling)

j. Steel Corrugated Decking

k. Steel Exterior Columns (Bending)


l. Steel Interior Columns (Buckling)

m. Steel Frames

n. One/Two-Way Unreinforced Masonry Walls

o. One/Two-Way Reinforced Masonry Walls

p. Masonry Pilasters

q. Wood or Timber Walls/Roofs/Beams

r. Wood or Timber Exterior Columns (Bending)

s. Wood or Timber Interior Columns (Buckling)

To produce a sampling (i.e. distribution) of human injuries, the interior spaces and exterior

grounds of structures are typically populated with arrays of people (See Figure 3). People are

composed of 19 unique and 28 total body components (See Figure 4). The material properties of

the 19 different body components are derived from empirical data, some sensitive to

overpressure (e.g. ears, lungs, GI system) and others sensitive to dynamic pressure or impulse

(e.g. ribs, long bones, vertebrae). People types include Man, Woman, and Child.

Figure 3. People Arrays within Structures

Figure 4. People Body Components

After creating structures, assigning materials and placing arrays of people HExDAM projects

only require two more things before executing a model run: the placement of one or more high

explosives (with a specified TNT equivalent mass) and the optional placement of a

pressure/impulse sampling grid (i.e. an XYZ-bounded volume with a user specified resolution).

ExDAM model runs typically take minutes (at most a few hours) to execute on a conventional,

relatively low-end laptop computer. Model runs produce results files typically less than 10MB

in size. Results files contain a backup copy of the project file and are, therefore, completely

independent of the source project file. Model run block results (i.e. peak incident

pressures/impulses, percent damages/injuries) are displayed in the 3D window with a variety of

color coding options. By default, low values of pressure/impulse/damage/injury are displayed

with a blue color, moderate values progress to a yellow color, and high values progress to a red

color (See Figure 5). Block results for user-selected blocks/structures are also displayed in a

variety of HTML table formats (See Figure 6). Block results for complex multi-block structures

(i.e. total percent damage and average incident pressures/impulses) are typically reported using

volume-weighted averages. Sample grid results (i.e. peak pressure/impulse distributions within

the bounds of an XYZ grid) are displayed using contour planes, iso-surfaces, and volume

rendering (See Figures 7, 8, 9). The same user-adjustable color coding options are used to

display low/moderate/high pressure/impulse values.


Figure 5. Block Damage/Injury

Figure 6. Block Damage/Injury Tables

Figure 7. Grid Contour Planes

Figure 8. Grid Iso-Surfaces

Figure 9. Grid Volume Rendering

West, Texas Project Development

An aerial/satellite image of West was first obtained from Google Earth, placed at ground level

and scaled to size. The geometry and construction characteristics of the various structures (i.e.

fertilizer plant, apartment building, nursing home, high school, middle school, residential houses,

commercial buildings) (See Figures 10 through 19) were then determined using Google Maps

Street View and various online aerial and street-level images from the extensive media coverage.

Interior details were included in the apartment building and nursing home. The schools,

commercial buildings, and residential houses were left hollow with no additional interior

walls/floors. All totaled the project structures are composed of 13880 structure blocks,

subdivided into 46148 blocks to increase sampling/computational resolution.


Figure 10. Satellite Image

Figure 11. All Structures

Figure 12. Apartment Buildings

Figure 13. Nursing Home w/ Roof

Figure 14. Nursing Home w/o Roof

Figure 15. High School

Figure 16. Middle School

Figure 17. Commercial Buildings

Figure 18. Fertilizer Plant

Figure 19. Residential Houses


The following materials (i.e. construction types) were assigned to the structures:

Structure Material Description

Apartment Building Res bldg w/ multistory wall-bearing, brick apt house

Nursing Home Res bldg w/ wood/steel stud wall, ltwt joist or truss roof

Middle School Bldg w/ reinforced masonry, 15 cm. walls, light roof

High School Bldg w/ reinforced masonry, 15 cm. walls, light roof

Residential Houses Res bldg w/ wood frame, house type

Commercial Buildings Ind bldg, lt steel frame, 4.5 mt. crane capacity

All of the structures were internally populated with over 340 people, evenly dispersed with

higher concentrations in the apartment building, nursing home, and intermediate school (See

Figure 20). A sample grid encompassing the entire scene and a 12.6 ton TNT high explosive

(~30 tons of AN using an R.E. facture of 0.42) was placed inside the fertilizer plant storage

building. All totaled, project development was completed within two working days.

Figure 20. Project Structures with Over 340 People Displayed at X20 Scale


West, Texas 12.6 ton TNT (30 ton AN) Explosion Simulation Results

Model runs took ~55 minutes on a conventional business PC (i.e. Dell Latitude Intel® Core™

i7-2760QM CPU @ 2.4GHz) producing results files ~7MB in size. The project’s structure

names and groups are defined in Figure 21.

Figure 21. Structure Names, Locations, and Groups

A contour plane located five feet above ground (See Figure 22) provides a quick idea of peak

incident over pressures. Notice how structures provide shielding to other structures (e.g. the

middle school provides significant shielding to the neighboring houses to the south west). Also

notice, the 1 and 0.5 psi lines are 1350 ft (0.26 mi) and 2225 ft (0.42 mi) from the explosion

center.

Figure 22. XY Overpressure Contours @ 5 ft Above Ground


Figure 23 displays color-coded structure incidence overpressures from 0.5 psi to 5 psi.

Figure 23. Structure Incident Overpressures

Figure 24 displays color-coded structure damage levels none, slight, moderate, and severe.

Figure 24. Structure Damage Levels


Figure 25 combines the overpressure contour plane (5 ft above ground) with color-coded

structure damage in a perspective view of the nearest, most exposed structures.

Figure 25. Perspective View of Overpressure Contour Plane 5 ft Above Ground with Color-Coded Structure Damage

Structures nearest the explosion were exposed to overpressures greater than 5 psi. Figure 26

provides a first visual comparison of predicted damage levels to actual.

Figure 26. Visual Comparison of Predicted vs. Actual Structure Damage


Figure 27 and Figure 28 display the incident overpressures and consequent injury levels to the

people closest to the blast. For a better view, the structures are hidden and the people are scaled

by a factor of 20.

Figure 27. Incident Overpressure to People Closest to the Blast

Figure 28. Injury Levels to People Closest to the Blast


Table 1 and Table 2 provide general information about incident pressures and average/maximum

damage/injury levels.

Table 1. Average(Maximum) Damage/Injury/Pressure/Impulse

Table 2. Damage & Injury Summary


From the above color-coded 3D images and corresponding results tables the following

observations and conclusions can be made:

A. Apartment Buildings (see Figures 29, 30, 31, 32) - The apartment building structure is

hit with a maximum of 5.07 psi and an average of 3.07 psi. By volume, 81.2% of the

structure is severely damaged, 13.0% moderately damaged, and 3.3% slightly damaged.

Assuming one person located in the middle of each apartment (i.e. 24 apartments

stretching from front to back of building, not 48/50 apartments as reported), on average

they experience 3.68 psi and at most 4.32 psi. Moderate injury due to high dynamic

pressures of up to 0.436 psi causing bone fractures (e.g. ribs, vertebrae, long bones) is

predicted.

Figure 29. Injury to 24 People in Apartment Building

Figure 30. Injury Table for Person Identified in Figure 29

Figure 31. Apartment Building - Comparison of Predicted to Actual Damage


Figure 32. Apartment Building and Neighboring Structures - Comparison of Predicted to Actual Damage

B. Nursing Home (see Figures 33, 34) – The nursing home is initially hit with almost 3 psi.

The average incident pressure throughout the entire structure is 1.31 psi. Average

structure damage of 32.3% is in the moderate range (i.e. over 30%) with 9.9% severely

damaged, 40.9% moderately damaged, and 10.1% slightly damaged. People located

behind windows nearest the explosion experience maximum overpressures of 2.4 psi and

maximum dynamic pressures of 0.14 psi. Injury levels to the people behind windows

nearest to the explosion are slight, consisting of ear drums due to overpressure and long

bones (e.g. ribs, vertebrae, long bones) due to dynamic pressure.

Figure 33. Injury to 64 People in Nursing Home

Figure 34. Nursing Home - Comparison of Predicted to Actual Damage


C. Middle School (see Figures 35, 36) – The middle school structure is hit with almost 3 psi

and experiences average overpressures of 1.43 psi. By volume, 23.4% of the structure is

severely damaged, 45.0% moderately damaged, and 19.6% slightly damaged. Occupants

experience overpressures as high as 1.85 psi and on average 1.05 psi. Overpressures and

dynamic pressures as high as 0.082 psi again produce slight ear and bone injuries.

Figure 35. Injury to 14 People in Middle School

Figure 36. Middle School - Comparison of Predicted to Actual Damage

D. Houses North of Apartments (Figure 37) - The houses north of the apartment building

are hit with up to 3.75 psi overpressure and 0.329 psi dynamic pressure producing mostly

moderate and severe damage. Slight injuries to ears and long bones are predicted.

Figure 37. Houses North of Apartments - Comparison of Predicted to Actual Damage


E. Houses North of Fertilizer Plant (Figure 38) - The nearest houses directly to the north

of the fertilizer plant are hit with up to 3.04 psi overpressure and 0.218 dynamic pressure.

Mostly moderate/severe damage and slight injuries are predicted.

Figure 38. Houses North of Fertilizer Plant - Comparison of Predicted to Actual Damage

F. South West Houses (Figure 39) – The houses directly south of the nursing home are hit

with up to 2.59 psi and 0.159 psi dynamic pressure, enough to generate moderate/severe

damage and some slight injuries.

Figure 39. Southwest Houses Hit with 6 psi Overpressure

G. Commercial Buildings - The commercial buildings toward the west are hit with up to

1.31 psi and an average of 0. 86 psi overpressure. Though there is no severe damage,

39.1% moderate and 50.1% slight structure damage by volume is predicted. No injuries

are predicted.

H. High School, South Houses - The high school and houses located directly south of the

fertilizer plant are hit with roughly 1 psi and experience average overpressures of roughly

0.5 psi. Slight damages of 55.7% and 77.4% by volume, respectively, and no injuries are

predicted.

In addition to images and tables ExDAM ECM results are typically reported using numerous

animation and video capture options. A preliminary video of this project, produced shortly after

the event, is available on YouTube [7] and an updated video for this specific conference paper

will be available on the Breeze ExDAM YouTube channel [8].


Conclusions

The explosion consequences in West, Texas (i.e. structure damage and human injury) are no

mystery to explosion experts. With a few simple calculations, an expert can accurately predict

the pressures incident on various structures and then, from experience, make reasonable

predictions about the damage and injury levels. Numerous software tools are available to help

facilitate such tasks. Scenarios for which blast pressure/impulse distributions pass around and

through numerous and/or geometrically complex structures (e.g. industrial plants, suburban/rural

cities, or downtown urban scenes with high-rise buildings) require more sophisticated software

tools to adequately assess/predict damage/injury levels.

The West, Texas ECM presented in this paper attempts to propose and demonstrate a fully three

dimensional simulation process easy, reliable, and affordable enough to be used by trained

technicians within the ranks of local emergency responders and/or their local community support

agencies. With ExDAM’s simple block structure modeling and fast phenomenological

computations, projects like West, Texas can be performed in hours or days using commonly

available computing resources. This process not only provides a means to quantify the

magnitude of threats but also helps to foster and sustain awareness of the threats by providing an

effective means to communicate the threats to all stakeholders (e.g. colorful multi-media 2D/3D

images/videos are typically more effective than stapled stacks of paper full of numbers).

As with all types of threats (e.g. hazardous release, fire, and explosion), investigations of past

events, such as West, Texas, seem to suggest that access to expertise and analytical tools for

consequence analysis are only part of what’s needed by local emergency responders and other

responsible community support/management agencies. The consensus seems to be that local

agencies not only need to identify and quantify potential threats to their communities but they

also need to “take action” so that adequate/prudent mitigation measures and emergency response

preparations can be designed, implemented, and maintained.

More alarmingly from an academic perspective, in the case of West, Texas, the CSB reports [1,

2, 3] clearly indicate that basic threat awareness, mitigation, and preparation measures are simply

being neglected across the U.S. Aside from the complicated political aspects, perhaps these

problems will be solved from the bottom up by developing and disseminating effective and

affordable (i.e. fast, easy, reliable) tools which naturally engage/induce/help emergency

responders and their support agencies to investigate, analyze, learn, communicate, educate,

organize and, ultimately (because all stakeholders understand, appreciate, and agree that there’s a

threat), take action to prevent and/or prepare for the threat.

In addition to on-going academic/government/industry testing and evaluation, ExDAM needs

access to any and all available blast vulnerability data (e.g. PI data such as the USACE CEDAW

[8]) so that users have a more complete set of structure materials to choose from. TCI is also

looking to collaborate with other organizations to continue the West, Texas analysis (or other

forensic/calibration/validation projects) to thoroughly test and evaluate ExDAM/HExDAM’s (or

VExDAM’s) overall process efficiency, effectiveness, and accuracy compared to actual event

damage/injury data and other predictive methods/processes. An Academic License Agreement is

available for qualified students/faculty/researches at educational/governmental institutions. TCI

is also looking to partner with local emergency responders and their supporting city/county/state


agencies to test, evaluate, and develop threat identification, analysis, communication, mitigation,

and preparation processes.

References

1. U.S. Chemical Safety Board, Preliminary Findings of the U.S. Chemical Safety Board from

its Investigation of the West Fertilizer Explosion and Fire, April 22, 2014

2. U.S. Chemical Safety Board, West Fertilizer Explosion And Fire Public Meeting, April 22,

2014

3. Testimony of Rafael Moure-Eraso, Ph.D., Chairperson, U.S. Chemical Safety Board, Before

the U.S. Senate Committee on Environment and Public Works, June 27, 2013Obama EO

4. The White House Office of the Press Secretary, Executive Order - Improving Chemical

Facility Safety and Security, August 01, 2013

5. Executive Order 13650 Working Group, Report for the President - Actions to Improve

Chemical Facility Safety and Security - A Shared Commitment, May 2014

6. BREEZE VASDIP (Vulnerability Assessment of Structurally Damaging Impulses and

Pressures) - Software Description Page Link:

(link broken - look for repaired link in http://www.breeze-software.com/exdam/ page)

7. BREEZE ExDAM West, Texas Explosion Analysis - Video Link:

(https://www.youtube.com/watch?v=45zetN2x6r4&list=PLwcBWH-

mGjwPsKQpSlPMKfAb6NjZLsAs-)

8. BREEZE Software - Video Channel Link:

(https://www.youtube.com/channel/UCh_3pHnt6zqZexFqBhCWKiA)

9. USACE CEDAW - Software Description Page Link:

(https://pdc.usace.army.mil/software/cedaw/)

http://www.breeze-software.com/exdam/

https://www.youtube.com/watch?v=45zetN2x6r4&list=PLwcBWH-mGjwPsKQpSlPMKfAb6NjZLsAs-

https://www.youtube.com/watch?v=45zetN2x6r4&list=PLwcBWH-mGjwPsKQpSlPMKfAb6NjZLsAs-

https://www.youtube.com/channel/UCh_3pHnt6zqZexFqBhCWKiA

https://pdc.usace.army.mil/software/cedaw/