NIST NCSTAR1-1J

Federal Building and Fire Safety Investigation of the

World Trade Center Disaster

Documentation of the Fuel System

for Emergency Power in World Trade

Center 7

U.S. Department of Commerce

Carlos M. Gutierrez, Secretary

Technology Administration

Michelle O'Neill, Acting Under Secretary for Technology

National Institute of Standards and Technology

William Jeffrey, Director

Raymond A. Grill Duane A. Johnson

Rolf Jensen & Associates, Inc.

September 2005
Disclaimer No. 1

Certain commercial entities, equipment, products, or materials are identified in this document in order to describe a

procedure or concept adequately or to trace the history of the procedures and practices used. Such identification is not intended to imply recommendation, endorsement, or implication that the entities, products, matehals, or equipment are necessarily the best available for the purpose. Nor does such identification imply a finding of fault or negligence by the National institute of Standards and Technology.

Disclaimer No. 2 The policy of NIST is to use the International System of Units (metric units) in all publications. In this document,

however, units are presented in metric units or the inch-pound system, whichever is prevalent in the discipline.

Disclaimer No. 3

Pursuant to section 7 of the National Construction Safety Team Act, the NIST Director has determined that certain evidence received by NIST in the course of this Investigation is "voluntarily provided safety-related information" that is "not directly related to the building failure being investigated" and that "disclosure of that information would inhibit the

voluntary provision of that type of information" (15 USC 7306c).

In addition, a substantial portion of the evidence collected by NIST in the course of the Investigation has been

provided to NIST under nondisclosure agreements.

Disclaimer No. 4 NIST takes no position as to whether the design or construction of a WTC building was compliant with any code

since, due to the destruction of the WTC buildings, NIST could not verify the actual (or as-built) construction, the

properties and condition of the materials used, or changes to the original construction made over the life of the

buildings. In addition, NIST could not verify the interpretations of codes used by applicable authorities in determining

compliance when implementing building codes. Where an Investigation report states whether a system was

designed or installed as required by a code provision, NIST has documentary or anecdotal evidence indicating

whether the requirement was met, or NIST has independently conducted tests or analyses indicating whether the requirement was met.

Use in Legal Proceedings

No part of any report resulting from a NIST investigation into a structural failure or from an investigation under the

National Construction Safety Team Act may be used in any suit or action for damages arising out of any matter mentioned in such report (15 USC 281a; as amended by P.L. 107-231).

National Institute of Standards and Technology National Construction Safety Team Act Report 1-1J

Natl. Inst. Stand. Technol. Natl. Constr. Sfty. Tm. Act Rpt. 1-1J, 84 pages (September 2005)

CODEN: NSPUE2

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 2005

For sale by the Superintendent of Documents, U.S. Government Printing Office

Internet: bookstore.gpo.gov — Phone: (202) 512-1800 — Fax: (202) 512-2250

Mail: Stop SSOP, Washington, DC 20402-0001
Abstract

This report was prepared to support the analysis of building and fire codes and standards of the National

Institute of Standards and Technology World Trade Center ( WTC) Investigation. As part of the investigation of WTC 7, the fuel oil distribution system is being analyzed as a possible cause of fire

initiation. The purpose of this report is to document the fuel oil distribution systems (including all t ucl oil tanks, pumps, generators, routing of the piping, and system functions) and the associated fire protection

features of the fuel oil system that existed in WTC 7 at the time of the collapse.

Keywords: Compartmentation, day tanks, diesel fuel, emergency generators, emergency power, fire protection, fire safety, fire sprinklers, fuel oil distribution system, fuel oil pumps, inspections, storage

tanks, World Trade Center.

NISTNCSTAR 1-1J, WTC Investigation iii
Abstract

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iv NISTNCSTAR 1-1J, WTC Investigation
Table of Contents

Abstract iii

List of Figures ix

List of Tables xi

List of Acronyms and Abbreviations xiii

Metric Conversion Table xv

Glossary xix

Preface xxi

Executive Summary xxxi

Chapter 1 Introduction 1

Chapter 2 Fuel Oil Provisions of the BCNYC 3

2 . 1 General Requirements 3

2.2 Fuel Oil Storage Equipment 3

2.3 Location of Tanks 4

2.4 Piping 6

2.5 Controls 9

Chapter 3 Base Building Design (1987) 11

3.1 Basic Layout 11

3.2 Component Details 1

3.3 Fire Protection 12

3.4 References 13

Chapter 4 Ambassador Construction Modification (1994) 17

4.1 Basic Layout 17

4.2 Component Details 17

4.3 Fire Protection 18

4.4 References 18

NISTNCSTAR1-1J.WTC Investigation v
Table of Contents

Chapter 5 American Express Modification (1994) 21

5.1 Basic Layout 21

5.2 Component Details 21

5.3 Fire Protection 22

5.4 References 22

Chapter 6 Mayor's Office of Emergency Management Modification (1999) 25

6.1 Basic Layout 25

6.2 Component Details 26

6.3 Fire Protection 27

6.4 References 27

Chapter?

Salomon Brothers Addition (1990) 31

7.1 Basic Layout 31

7.2 Component Details 3

7.3 Fire Protection 32

7.4 References 32

Chapter 8 Final Configuration 35

Chapter 9 System Performance.... 41

9. 1 Base Building Fuel Oil Distribution System 41

9.1.1 Liquid Level Switches/Detectors and Collecting Pans/Rupture Basins 41

9. 1 .2 Fusible Link Gate Valve 42

9.1.3 Anti-siphon Valve and Check Valve 42

9.1.4 Foot Valve 43

9.1.5 Pressure Relief Valve ;. 43

9.1.6 Solenoid Valve 43

9.1.7 Tank Selector Valve 43

9.2 Salomon Brothers Fuel Oil Distribution System 46

9.3 System Capacities 48

vi NISTNCSTAR 1-1J, WTC Investigation
Draft for Public Comment

Chapter 10

Maintenance History 49

NISTNCSTAR 1-1J,WTC Investigation vii
Table of Contents

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viii NISTNCSTAR 1-1J, WTC Investigation
List OF Figures

Figure P-1. The eight projects in the federal building and fire safety investigation of the WTC

disaster xxiii

Figure 3-1. Base Building 1st floor fuel oil distribution plan 14

Figure 3-2. Base Building 5th floor fuel oil distribution plan 14

Figure 3-3. Base Building section plan of fuel oil distribution components 15

Figure 4-1. First floor fuel oil distribution plan after the Ambassador Construction modification 19

Figure 4-2. Ninth floor fuel oil distribution plan after the Ambassador Construction modification 19

Figure 4-3. Section plan of fuel oil distribution components after the Ambassador Construction

modification 20

Figure 5-1. First floor fuel oil distribution plan after the American Express modification 23

Figure 5-2. Seventh floor fuel oil distribution plan after the American Express modification 23

Figure 5-3. Eighth floor fuel oil distribution plan after the American Express modification 23

Figure 5-4. Section plan of fuel oil distribution components after the American Express

modification 24

Figure 6-1. First floor fuel oil distribution plan after the OEM modification 28

Figure 6-2. Seventh floor fuel oil distribution plan after the OEM modification 28

Figure 6-3. Section plan of fuel oil distribution components after the OEM modification 29

Figure 7-1. First floor fuel oil distribution plan after the Salomon Brothers addition 33

Figure 7-2. Fifth floor fiael oil distribution plan after the Salomon Brothers addition 33

Figure 7-3. Section plan of fuel oil distribution components after the Salomon Brothers addition 34

Figure 8-1 . Section plan showing the final locations of the fuel oil distribution components 36

Figure 8-2. Final location of 1st floor fuel oil distribution components 37

Figure 8-3. Final location of 5th floor fuel oil distribution components 37

Figure 8^. Final location of 7th floor fuel oil distribution components 38

Figure 8-5. Final location of 8th floor fuel oil distribution components 38

Figure 8-6. Final location of 9th floor fuel oil distribution components 39

NISTNCSTAR1-1J, WTC Investigation ix
List of Figures

Figure 9-1. Typical layout of critical devices in Base Building sub-systems 44

Figure 9-2. Layout of critical devices in Salomon Brothers system 47

X NISTNCSTAR 1-1J, WTC Investigation
List of Tables

Table P-1 . Federal building and fire safety investigation of the WTC disaster xxii

Table P-2. Public meetings and briefings of the WTC Investigation xxv

Table 9-1 . Critical fuel oil devices installed in Base Building sub-systems 45

Table 9-2. Capacity of fuel oil components throughout WTC 7 48

Table 10-1. Maintenance schedule of fuel oil pumps and generators 49

NISTNCSTAR 1-1J, WTC Investigation xi
List of Tables

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xii NIST NCSTAR 1-1J, WTC Investigation
List of Acronyms and Abbreviations

Acronyms

Building Code of the City of New York (Local Law 76)

BSA New York City Board of Standards and Appeals

FOR fuel oil return FOS fuel oil supply

MER Mechanical Equipment Room

NIST National Institute of Standards and Technology

OEM Mayor's Office of Emergency Management

PANYNJ Port Authority of New York and New Jersey

RS Reference Standard to the Building Code of the City of New York

WTC World Trade Center

WTC 1 World Trade Center 1 (North Tower)

WTC 2 World Trade Center 2 (South Tower)

WTC 7 World Trade Center 7

Abbreviations

op degrees Fahrenheit

ft foot

ft- square foot

gal gallon

gph gallons per hour

gpm gallons per minute

h hour

hp horsepower

Hz hertz

in. inch

kVa kilovoltampere

kW kilowatt

psi pounds per square inch

NISTNCSTAR 1-1J, WTC Investigation xiu
List of Acronyms and Abbreviations

rpm revolutions per minute

V volt

XIV NISTNCSTAR 1-1J, WTC Investigation
Metric Conversion Table

To convert from to Multiply by

AREA AND SECOND MOMENT OF AREA

square foot {ft")

square inch (in.")

square inch (in.")

square yard (yd")

square meter (m")

square meter (m")

square centimeter (cm'

square meter (m")

9.290 304 E-02

6.4516 E-04

6.451 6 E+00

8.361 274 E-01

ENERGY (includes WORK)

kilowatt hour (kW • h)

quad (1015 BtuIT)

therm (U.S.)

ton of TNT (energy equivalent)

watt hour (W h)

watt second (W • s)

joule (J)

joule (J)

joule (J)

joule (J)

joule (J)

joule (J)

3.6 E+06

1.055 056E+18

1.054 804 E+08

4.184 E+09

3.6E+03

1.0 E+00

FORCE

dyne (dyn)

kilogram-force (kgf)

kilopond (kilogram-force) (kp)

kip(l kip=l,000 Ibf)

kip(l kip= 1,000 Ibf)

pound-force (Ibf)

newton (N)

newton (N)

newton (N)

newton (N)

kilonewton (kN)

newton (N)

l.OE-05

9.806 65 E+00

9.806 65 E+00

4.448 222 E+03

4.448 222 E+00

4.448 222 E+00

FORCE DIVIDED BY LENGTH

pound-force per foot (Ibf/ft)

pound-force per inch (Ibf/in.)

newton per meter (N/m)

newton per meter (N/m)

1.459 390 E+01

1.751 268 E+02

HEAT FLOW RATE

calorieth per minute (calth/min)

calorieth per second (calth/s)

kilocalorieth per minute (kcalth/min)

kilocalorieth per second (kcalth/s)

watt (W)

watt (W)

watt (W)

watt (W)

6.973 333 E-02

4.184 E+00

6.973 333 E+01

4.184 E+03

NISTNCSTAR 1-1J, WTC Investigation XV
Metric Conversion Table

To convert from ; to Multiply by

LENGTH

foot (ft) meter (m) 3.048 E-01

inch (in) meter (m) 2.54 E-02

inch (in.) centimeter (cm) 2.54 E+00

micron (in) meter (m) l.OE-06

yard (yd) meter (m) 9.144 E-01

MASS and MOMENT OF INERTIA

kilogram-force second squared

per meter (kgf s'/m) kilogram (kg) 9.806 65 E+00

pound foot squared (lb ft") kilogram meter squared (kg m") 4.214 011 E-02

pound inch squared (lb in.") kilogram meter squared (kg • m") 2.926 397 E-04

ton. metric (t) kilogram (kg) l.OE+03

ton, short (2.000 lb) kilogram (kg) 9.071 847 E+02

MASS DIVIDED BY AREA

pound per square foot (lb/ft") kilogram per square meter (kg/m") 4.882 428 E+00

pound per square inch

(nor pound force) (lb/in.") kilogram per square meter (kg/m") 7.030 696 E+02

MASS DIVIDED BY LENGTH

pound per foot (lb/ft) kilogram per meter (kg/m) 1.488 164 E+00

pound per inch (lb/in.) kilogram per meter (kg/m) 1.785 797 E+01

pound per yard (lb/yd) kilogram per meter (kg/m) 4.960 546 E-01

PRESSURE or STRESS (FORCE DIVIDED BY AREA)

kilogram-force per square centimeter (kgf/cm") pascal (Pa) 7.0WD VJ C'yjH

kilogram-force per square meter (kgf/m") pascal (Pa) y.ouyj uj iL'yjyj

kilogram-force per square millimeter (kgf/mm") pascal (Pa) 9.806 65 E+06

kip per square inch (ksi) (kip/in.") pascal (Pa) 6.894 757 E+06

kip per square inch (ksi) (kip/in.") kilopascal (kPa) 6.894 757 E+03

pound-force per square foot (Ibf/ft") pascal (Pa) 4.788 026 E+01

pound-force per square inch (psi) (Ibf/in.") pascal (Pa) 6.894 757 E+03

pound-force per square inch (psi) (Ibf/in.') kilopascal (kPa) 6.894 757 E+00

psi (pound-force per square inch) (Ibf/in.") pascal (Pa) 6.894 757 E+03

psi (pound-force per square inch) (Ibf/in.") kilopascal (kPa) 6.894 757 E+00

XVI NISTNCSTAR 1-1J, WTC Investigation
Metric Conversion Table

To convert from to Multiply by

TEMPERATURE

degree Celsius (°C)

degree centigrade

degree Fahreniieit (°F)

degree Fahrenheit (°F)

kelvin (K)

kelvin (K)

degree Celsius (°C)

degree Celsius (°C)

kelvin (K)

degree Celsius (°C)

T/K = t/°C + 273.15

t/°C * t /deg. cent.

t/°C = (t/°F-32)/1.8 T/K = (t/°F + 459.67)71.8

t/°C = T/K 2 273.15

TEMPERATURE INTERVAL

degree Celsius (°C)

degree centigrade

degree Fahrenheit (°F)

degree Fahrenheit (°F)

degree Rankine (°R)

kelvin (K)

degree Celsius (°C)

degree Celsius (°C)

kelvin (K)

kelvin (K)

1.0 E+00

l.OE+00

5.555 556 E-01

5.555 556 E-01

5.555 556E-01

VELOCITY (includes SPEED)

foot per second (ft/s)

inch per second (in./s)

kilometer per hour (km/h)

mile per hour (mi/h)

mile per minute (mi/min)

meter per second (m/s)

meter per second (m/s)

meter per second (m/s)

kilometer per hour (km/h)

meter per second (m/s)

3.048 E-01

2.54 E-02

2.777 778 E-01

1.609 344 E+00

2.682 24 E+01

VOLUME (includes CAPACITY)

cubic foot (ft') cubic meter (m')

cubic mch (in.' ) cubic meter (m')

cubic yard (yd') cubic meter (m')

gallon (U.S.) (gal) cubic meter (m')

gallon (U.S.) (gal) liter (L)

liter (L) cubic meter (m')

ounce (U.S. fluid) (fl oz) cubic meter (m')

ounce (U.S. fluid) (fl oz) . milliliter (mL)

2.831 685 E-02

1.638 706 E-05

7.645 549 E-01

3.785 412 E-03

3.785 412 E+00

1.0 E-03

2.957 353 E-05

2.957 353 E+01

NISTNCSTAR 1-1J, WTC Investigation xvii
Metric Conversion Table

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XVlll NISTNCSTAR 1-1J, WTC Investigation
Glossary

active fire protection - A means to help prevent the loss of life and property from fire by extinguishing,

suppressing, or controlling a fire through functional systems. Sprinkler systems, fire alarm systems, and

smoke control systems are examples of active fire protection.

combustible - A material that is not detennined to be noncombustible.

dry pipe sprinkler system - A fire sprinkler system in which the piping up to the sprinkler heads is

initially filled with air. Once a sprinkler head operates, water is released into the piping and continues to flow out the activated sprinkler(s) until the system is shut off.

fire alarm system - A system, automatic or manual, arranged to give a signal indicating a fire emergency

and initiate the appropriate response.

fire resistance rating - The time in hours that materials or their assemblies will withstand fire exposure

as determined by a fire test.

fireproofing - Materials or assemblies used to provide a fire resistance rating to a building component.

firestop - A solid or compact, tight closure to retard the spread of flames or hot gases within concealed

spaces.

noncombustible - A material that, in the fomi in which it is used in construction, will not ignite and bum

when subjected to fire. However, any material which liberates flammable gas when heated to any

temperature up to 1 ,380 °F for 5 min shall not be considered noncombustible.

passive fire protection - Fire protection features that are incorporated into the building construction or

building materials that do not rely on active fire protection methods to limit fire ignition, fire growth, or

material failure. Fire separations and divisions, sprayed fire-resistive material, and enclosing structural members with noncombustible materials are examples of passive fire protection.

wet pipe sprinkler system - A fire sprinkler system in which the piping is filled with pressurized water

at all times. Water is immediately discharged when a sprinkler head operates and continues to flow out

the activated sprinkler(s) until the system is shut off.

NISTNCSTAR 1-1J, WTC Investigation xix
Glossary

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XX NISTNCSTAR 1-1J, WTC Investigation
Preface

Genesis of This Investigation

Immediately following the terrorist attack on the World Trade Center (WTC) on September 1 1 , 2001, the Federal Emergency Management Agency (FEMA) and the American Society of Civil Engineers began

planning a building performance study of the disaster. The week of October 7, as soon as the rescue and

search efforts ceased, the Building Perfonnance Study Team went to the site and began its assessment. This was to be a brief effort, as the study team consisted of experts who largely volunteered their time

away from their other professional commitments. The Building Performance Study Team issued its report in May 2002, fulfilling its goal "to detemiine probable failure mechanisms and to identify areas of

future investigation that could lead to practical measures for improving the damage resistance of buildings

against such unforeseen events."

On August 21, 2002, with funding from the U.S. Congress through FEMA, the National Institute of

Standards and Technology (NIST) announced its building and fire safety investigation of the WTC

disaster. On October 1, 2002, the National Construction Safety Team Act (Public Law 107-231), was

signed into law. The NIST WTC Investigation was conducted under the authority of the National

Construction Safety Team Act.

The goals of the investigation of the WTC disaster were:

• To investigate the building construction, the materials used, and the technical conditions that contributed to the outcome of the WTC disaster.

• To serve as the basis for: - Improvements in the way buildings are designed, constructed, maintained, and used; - Improved tools and guidance for industry and safety officials; - Recommended revisions to cuiTent codes, standards, and practices; and - Improved public safety.

The specific objectives were:

1. Determine why and how WTC I and WTC 2 collapsed following the initial impacts of the

aircraft and why and how WTC 7 collapsed;

2. Determine why the injuries and fatalities were so high or low depending on location,

including all technical aspects of fire protection, occupant behavior, evacuation, and

emergency response;

3. Determine what procedures and practices were used in the design, construction, operation,

and maintenance of WTC 1,2, and 7; and

4. Identify, as specifically as possible, areas in current building and fire codes, standards, and

practices that warrant revision.

NISTNCSTAR 1-1J, WTC Investigation xxi
Preface

NIST is a nonregulatory agency of the U.S. Department of Commerce's Technology Administration. The

purpose of NIST investigations is to improve the safety and structural integrity of buildings in the United

States, and the focus is on fact finding. NIST investigative teams are authorized to assess building

performance and emergency response and evacuation procedures in the wake of any building failure that has resuhed in substantial loss of life or that posed significant potential of substantial loss of life. NIST

does not have the statutory authority to make findings of fault nor negligence by individuals or

organizations. Further, no part of any report resulting from a NIST investigation into a building failure or from an investigation under the National Construction Safety Team Act may be used in any suit or action

for damages arising out of any matter mentioned in such report (15 USC 281a, as amended by Public

Law 107-231).

Organization of the Investigation

The National Construction Safety Team for this Investigation, appointed by the then NIST Director, Dr. Arden L. Bement, Jr., was led by Dr. S. Shyam Sunder. Dr. William L. Grosshandler served as Associate Lead Investigator, Mr. Stephen A. Cauffman sei^ved as Program Manager for Administration,

and Mr. Harold E. Nelson served on the team as a private sector expert. The Investigation included eight

interdependent projects whose leaders comprised the remainder of the team. A detailed description of

each of these eight projects is available at http://wtc.nist.gov. The purpose of each project is summarized

in Table P-1, and the key interdependencies among the projects are illustrated in Fig. P-1.

Table P-1. Federal building and fire safety investigation of the WTC disaster.

Technical Area and Project Leader Project Purpose

Analysis of Building and Fire Codes and

Practices; Project Leaders: Dr. H. S. Lew

and Mr. Richard W. Bukowski

Document and analyze the code provisions, procedures, and

practices used in the design, construction, operation, and

maintenance of the structural, passive fire protection, and

emergency access and evacuation systems of WTC I, 2, and 7. Baseline Structural Performance and

Aircraft Impact Damage Analysis; Project Leader: Dr. Fahim H. Sadek

Analyze the baseline performance of WTC 1 and WTC 2 under

design, service, and abnormal loads, and aircraft impact damage on

the structural, fire protection, and egress systems.

Mechanical and Metallurgical Analysis of

Structural Steel; Project Leader: Dr. Frank

W. Gayle

Determine and analyze the mechanical and metallurgical properties

and quality of steel, weldments, and connections from steel recovered from WTC I, 2, and 7. Investigation of Active Fire Protection Systems; Project Leader: Dr. David

D. Evans; Dr. William Grosshandler

Investigate the performance of the active fire protection systems in WTC 1, 2, and 7 and their role in fire control, emergency response, and fate of occupants and responders.

Reconstruction of Thermal and Tenability

Environment; Project Leader: Dr. Richard

G. Gann

Reconstruct the time-evolving temperature, thermal environment,

and smoke movement in WTC 1 , 2, and 7 for use in evaluating the

structural performance of the buildings and behavior and fate of

occupants and responders.

Structural Fire Response and Collapse

Analysis; Project Leaders: Dr. John

L. Gross and Dr. Theresa P. McAllister

Analyze the response of the WTC towers to fires with and without

aircraft damage, the response of WTC 7 in fires, the performance

of composite steel-trussed floor systems, and detemiine the most

probable structural collapse sequence for WTC 1. 2, and 7. Occupant Behavior, Egress, and Emergency

Communications; Project Leader: Mr. Jason D. Averill

Analyze the behavior and fate of occupants and responders, both

those who survived and those who did not, and the performance of

the evacuation system.

Emergency Response Technologies and

Guidelines; Project Leader: Mr. J. Randall Lawson

Document the activities of the emergency responders from the time

of the terrorist attacks on WTC 1 and WTC 2 until the collapse of

WTC 7, including practices followed and technologies used.

XXll NISTNCSTAR 1-1J, WTC Investigation
Preface

NIST WTC Investigation Projects

Figure P-1. The eight projects in the federal building and fire safety

investigation of the WTC disaster.

National Construction Safety Team Advisory Committee

The NIST Director also established an advisory committee as mandated under the National Construction

Safety Team Act. The initial members of the committee were appointed following a public solicitation. These were:

• Paul Fitzgerald, Executive Vice President (retired) FM Global, National Construction Safety

Team Advisory Committee Chair

• John Barsom, President, Barsom Consulting, Ltd.

• John Bryan, Professor Emeritus, University of Maryland

• David Collins, President, The Preview Group, Inc.

• Glenn Corbett, Professor, John Jay College of Criminal Justice

• Philip DiNenno, President, Hughes Associates, Inc.

NISTNCSTAR 1-1J, WTC Investigation xxiii
Preface

• Robert Hanson, Professor Emeritus, University of Michigan

• Charles Thornton, Co-Chairman and Managing Principal, The Thomton-Tomasetti Group,

Inc.

• Kathleen Tiemey, Director, Natural Hazards Research and Applications Inforaiation Center,

University of Colorado at Boulder

• Foraian Williams, Director, Center for Energy Research, University of California at San

Diego

This National Construction Safety Team Advisory Committee provided technical advice during the Investigation and commentaiy on drafts of the Investigation reports prior to their public release. NIST

has benefited from the work of many people in the preparation of these reports, including the National

Construction Safety Team Advisoi'y Committee. The content of the reports and recominendations,

however, are solely the responsibility of NIST.

Public Outreach

During the course of this Investigation, NIST held public briefings and meetings (listed in Table P-2) to

solicit input from the public, present preliminary findings, and obtain comments on the direction and

progress of the Investigation from the public and the Advisory Committee.

NIST maintained a publicly accessible Web site during this Investigation at http://wtc.nist.gov. The site contained extensive information on the background and progress of the Investigation.

NIST's WTC Public-Private Response Plan

The collapse of the WTC buildings has led to broad reexamination of how tall buildings are designed,

constructed, maintained, and used, especially with regard to major events such as fires, natural disasters,

and teiTorist attacks. Reflecting the enhanced interest in effecting necessary change, NIST, with support

from Congress and the Administration, has put in place a program, the goal of which is to develop and

implement the standards, technology, and practices needed for cost-effective improvements to the safety

and security of buildings and building occupants, including evacuation, emergency response procedures,

and threat mitigation.

The strategy to meet this goal is a three-part NIST-led public-private response program that includes:

• A federal building and fire safety investigation to study the most probable factors that contributed to post-aircraft impact collapse of the WTC towers and the 47-story WTC 7

building, and the associated evacuation and emergency response experience.

• A research and development (R&D) program to (a) facilitate the implementation of

recommendations resulting from the WTC Investigation, and (b) provide the technical basis

for cost-effective improvements to national building and fire codes, standards, and practices

that enhance the safety of buildings, their occupants, and emergency responders.

xxiv NISTNCSTAR 1-1J, WTC Investigation
Preface

Table P-2. Public meetings and briefings of the WTC Investigation.

Date Location Principal Aj^cnda

June 24, 2002 New York City, NY Public meeting: Public comments on the Dra/l Plan lor thc pending WTC Investigation.

August 21, 2002 Gaithersburg, MD Media briefing announcing the formal start of the Investigation.

December 9, 2002 Washington, DC Media briefing on release of the Public Update and NIST request

for photographs and videos. April 8, 2003 New York City, NY Joint public forum with Columbia University on first-person interviews. April 29-30, 2003 Gaithersburg, MD NCST Advisory Committee meeting on plan for and progress on WTC Investigation with a public comment session. May 7, 2003 New York City, NY Media briefing on release of May 2003 Progress Report.

August 26-27, 2003 Gaithersburg, MD NCST Advisory Committee meeting on status of the WTC

investigation with a public comment session. Sentemher 1 7 ""OO^ New Ynrk Citv NY iVlCUId allLl UUUII^ UilCllll^ SJlk 1 111 I lallL/ll \Jl lllciX. I j\J 11 Uuld

collection projects.

December 2-3, 2003 Gaithersburg, MD NCST Advisory Committee meeting on status and initial results and release of the Public Update with a public comment session. New Ynrk ritv NY r UUiiC IllCCllllg Ull UlUUlC^a allU Ul CI 111 llllal y lll]UlllH,o WIUl UUUIIL comments on issues to be considered in formulating final recommendations.

June 18, 2004 New York City, NY Media/public briefing on release of June 2004 Progress Report. Tune ''9—93 ''004 VJallllCloUUl^, rVlLJ inV^j J AVUVJSUiy \^ UlIllllHltC lllCCllll^ *JI1 lilt DlUlUo Ul ullKJ preliminary findings from the WTC Investigation with a public

comment session. Mr^rtViKmnV IT 1 N UI UlUl VJUK, IL Piinlir* \/if*\x/in(T r\T ctQnHiirH Tiff* rfcictiinr'p tpct c\t W/ii t\r\r\T rUUIIL. VlCWlllg KJi >lallLlul U lilt 1 1 olJilClilt t ItSlUl VV 1\„ 1 l\j\Jl system at Underu'riters Laboratories. Inc. October 19-20, 2004 Gaithersburg, MD NCST Advisory Committee meeting on status and near complete

&tl \Jl iJl 1 1 1 1 1 1 1 1 lal y j111uiiil;c> Willi ci uuuiit t\Ji i ill itiii jtooi'^ii. November 22, 2004 Gaithersburg, MD NCST Advisory Committee discussion on draft annual report to

V_ Ul 1^1 too., a UUUlIt tUlllllltlll otoolVJll^ dllU Cl tlUotU otoolUil lU discuss pre-draft recommendations for WTC Investigation.

New Ynrk Titv NY IVltUla allU UUUllt UlltlUle^ Ull Itltuot Ul lilt UlUUclUlt CUliaUot sequence for the WTC towers and draft reports for the projects on

codes and practices, evacuation, and emergency response. June 23, 2005 New York City, NY Media and public briefing on release of all draft reports for the WTC towers and draft recommendations for public comment.

September 12-13,

2005

Gaithersburg, MD NCST Advisory Committee meeting on disposition of public

comments and update to draft reports for the WTC towers. September 13-15,

2005

Gaithersburg, MD WTC Technical Conference for stakeholders and technical community for dissemination of findings and recommendations

and opportunity for public to make technical comments.

• A dissemination and technical assistance program (DTAP) to (a) engage leaders of the construction and building community in ensuring timely adoption and widespread use of

proposed changes to practices, standards, and codes resulting from the WTC Investigation

and the R&D program, and (b) provide practical guidance and tools to better prepare facility owners, contractors, architects, engineers, emergency responders, and regulatory authorities

to respond to future disasters. The desired outcomes are to make buildings, occupants, and first responders safer in future disaster events.

NISTNCSTAR 1-1J, WTC Investigation XXV
Preface

National Construction Safety Team Reports on the WTC Investigation

A final report on the collapse of the WTC towers is being issued as NIST NCSTAR 1 . A companion

report on the collapse of WTC 7 is being issued as NIST NCSTAR lA. The present report is one of a set that provides more detailed documentation of the Investigation findings and the means by which these

technical results were achieved. As such, it is part of the archival record of this Investigation. The titles of the full set of Investigation publications are:

NIST (National Institute of Standards and Technology). 2005. Federal Building and Fire Safety

Investigation ofthe World Trade Center Disaster: Final Report on the Collapse ofthe World Trade

Center Towers. NIST NCSTAR 1. Gaithersburg, MD, September.

NIST (National Institute of Standards and Technology). 2006. Federal Building and Fire Safety

Investigation ofthe World Trade Center Disaster: Final Report on the Collapse of World Trade Center 7. NIST NCSTAR lA. Gaithersburg, MD.

Lew, H. S., R. W. Bukowski, and N. J. Carino. 2005. Federal Building and Fire Safety Investigation of

the World Trade Center Disaster: Design, Construction, and Maintenance ofStructural and Life Safety

Systems. NIST NCSTAR 1-1. National Institute of Standards and Technology. Gaithersburg, MD,

September.

Fanella, D. A., A. T. Derecho, and S. K. Ghosh. 2005. Federal Building and Fire Safety

Investigation ofthe World Trade Center Disaster: Design and Construction ofStructural Systems.

NIST NCSTAR 1-1 A. National Institute of Standards and Technology. Gaithersburg, MD,

September.

Ghosh, S. K., and X. Liang. 2005. Federal Building and Fire Safety Investigation ofthe World

Trade Center Disaster: Comparison ofBuilding Code Structural Requirements. NIST

NCSTAR 1-lB. National Institute of Standards and Technology. Gaithersburg, MD, September.

Fanella, D. A., A. T. Derecho, and S. K. Ghosh. 2005. Federal Building and Fire Safety

Investigation ofthe World Trade Center Disaster: Maintenance and Modifications to Structural

Systems. NIST NCSTAR 1-lC. National Institute of Standards and Technology. Gaithersburg,

MD, September.

Grill, R. A., and D. A. Johnson. 2005. Federal Building and Fire Safety Investigation ofthe World

Trade Center Disaster: Fire Protection and Life Safety Provisions Applied to the Design and

Construction of World Trade Center I, 2, and 7 and Post-Construction Provisions Applied after Occupancy. NIST NCSTAR 1-lD. National Institute of Standards and Technology. Gaithersburg,

MD, September.

Razza, J. C, and R. A. Grill. 2005. Federal Building and Fire Safety Investigation ofthe World

Trade Center Disaster: Comparison ofCodes, Standards, and Practices in Use at the Time ofthe Design and Construction of World Trade Center I, 2, and 7. NIST NCSTAR I-IE. National

Institute of Standards and Technology. Gaithersburg, MD, September.

Grill, R. A., D. A. Johnson, and D. A. Fanella. 2005. Federal Building and Fire Safety'

Investigation ofthe World Trade Center Disaster: Comparison ofthe 1968 and Current (2003) New

XXVI NIST NCSTAR 1-1J, WTC Investigation
Preface

York City Building Code Provisions. NIST NCSTAR 1 - 1 F. National Institute of Standards and

Technology. Gaithersburg, MD, September.

Grill, R. A., and D. A. Johnson. 2005. Federal Building and Fire Safety Investigation of the World

Trade Center Disaster: Amendments to the Fire Protection and Life Safety Provisions ofthe New

York City Building Code by Local Laws Adopted While World Trade Center 1, 2, and 7 Were in Use. NIST NCSTAR 1-lG. Nationallnstitute of Standards and Technology. Gaithersburg, MD,

September.

Grill, R. A., and D. A. Johnson. 2005. Federal Building and Fire Safety Investigation ofthe World

Trade Center Disaster: Post-Construction Modifications to Fire Protection and Life Safety Systems

of World Trade Center 1 and 2. NIST NCSTAR 1-lH. National Institute of Standards and

Technology. Gaithersburg, MD, September.

Grill, R. A., D. A. Johnson, and D. A. Fanella. 2005. Federal Building and Fire Safety Investigation

ofthe World Trade Center Disaster: Post-Construction Modifications to Fire Protection, Life

Safety, and Structural Systems of World Trade Center 7. NIST NCSTAR 1-1 1. National Institute of

Standards and Technology. Gaithersburg, MD, September.

Grill, R. A., and D. A. Johnson. 2005. Federal Building and Fire Safety Investigation ofthe World

Trade Center Disaster: Design, Installation, and Operation ofFuel System for Emergency Power in World Trade Center 7. NIST NCSTAR 1-1 J. National Institute of Standards and Technology.

Gaithersburg, MD, September.

Sadek, F. 2005. Federal Building and Fire Safety Investigation ofthe World Trade Center Disaster:

Baseline Structural Performance and Aircraft Impact Damage Analysis ofthe World Trade Center

Towers. NIST NCSTAR 1-2. National Institute of Standards and Technology. Gaithersburg, MD,

September.

Faschan, W. J., and R. B. Garlock. 2005. Federal Building and Fire Safety Investigation ofthe World Trade Center Disaster: Reference Structural Models and Baseline Performance Analysis of

the World Trade Center Towers. NIST NCSTAR 1-2A. National Institute of Standards and

Technology. Gaithersburg, MD, September.

Kirkpatrick, S. W., R. T. Bocchieri, F. Sadek, R. A. MacNeill, S. Holmes, B. D. Peterson,

R. W. Cilke, C. Navarro. 2005. Federal Building and Fire Safety Investigation ofthe World Trade

Center Disaster: Analysis ofAircraft Impacts into the World Trade Center Towers, NIST

NCSTAR 1-2B. National Institute of Standards and Technology. Gaithersburg, MD, September.

Gayle, F. W., R. J. Fields, W. E. Luecke, S. W. Banovic, T. Foecke, C. N. McCowan, T. A. Siewert, and

J. D. McColskey. 2005. Federal Building and Fire Safety Investigation ofthe World Trade Center

Disaster: Mechanical and Metallurgical Analysis ofStructural Steel. NIST NCSTAR 1-3. National

Institute of Standards and Technology. Gaithersburg, MD, September.

Luecke, W. E., T. A. Siewert, and F. W. Gayle. 2005. Federal Building and Fire Safety

Investigation ofthe World Trade Center Disaster: Contemporaneous Structural Steel

Specifications. NIST Special Publication 1-3 A. National Institute of Standards and Technology.

Gaithersburg, MD, September.

NIST NCSTAR 1-1J, WTC Investigation xxvn
Preface

Banovic, S. W. 2005. Federal Building and Fire Safety Investigation ofthe World Trade Center

Disaster: Steel Inventoiy and Identification. NIST NCSTAR 1-3B. National Institute of Standards

and Technology. Gaithersburg, MD, September.

Banovic, S. W., and T. Foecke. 2005. Federal Building and Fire Safety Investigation ofthe World

Trade Center Disaster: Damage and Failure Modes ofStructural Steel Components. NIST

NCSTAR 1-3C. Nationallnstitute of Standards and Technology. Gaithersburg, MD, September.

Luecke, W. E., J. D. McColskey, C. N. McCowan, S. W. Banovic, R. J. Fields, T. Foecke,

T. A. Siewert, and F. W. Gayle. 2005. Federal Building and Fire Safety Investigation ofthe World

Trade Center Disaster: Mechanical Properties ofStructural Steels. NIST NCSTAR 1-3D.

National Institute of Standards and Technology. Gaithersburg, MD, September.

Banovic, S. W., C. N. McCowan, and W. E. Luecke. 2005. Federal Building and Fire Safety

Investigation ofthe World Trade Center Disaster: Physical Properties ofStructural Steels. NIST

NCSTAR 1-3E. National Institute of Standards and Technology. Gaithersburg, MD, September.

Evans, D. D., R. D. Peacock, E. D. Kuligowski, W. S. Dols, and W. L. Grosshandler. 2005. Federal

Building and Fire Safet\' Investigation ofthe World Trade Center Disaster: Active Fire Protection

Systems. NIST NCSTAR 1-4. National Institute of Standards and Technology. Gaithersburg, MD,

September.

Kuligowski, E. D., D. D. Evans, and R. D. Peacock. 2005. Federal Building and Fire Safety

Investigation of the World Trade Center Disaster: Post-Construction Fires Prior to September II, 2001. NIST NCSTAR 1-4A. National Institute of Standards and Technology. Gaithersburg, MD,

September.

Hopkins, M., J. Schoenrock, and E. Budnick. 2005. Federal Building and Fire Safet)' Investigation

ofthe World Trade Center Disaster: Fire Suppression Systems. NIST NCSTAR 1-4B. National

Institute of Standards and Technology. Gaithersburg, MD, September.

Keough, R. J., and R. A. Grill. 2005. Federal Building and Fire Safet)' Investigation ofthe World

Trade Center Disaster: Fire Alarm Systems. NIST NCSTAR 1 -4C. National Institute of Standards

and Technology. Gaithersburg, MD, September.

Ferreira, M. J., and S. M. Strege. 2005. Federal Building and Fire Safety Investigation ofthe World Trade Center Disaster: Smoke Management Systems. NIST NCSTAR 1-4D. National

Institute of Standards and Technology. Gaithersburg, MD, September.

Gann, R. G., A. Hamins, K. B. McGrattan, G. W. Mulholland, H. E. Nelson, T. J. Ohlemiller,

W. M. Pitts, and K. R. Prasad. 2005. Federal Building and Fire Safety Investigation ofthe World Trade

Center Disaster: Reconstruction of the Fires in the World Trade Center Towers. NIST NCSTAR 1-5. National Institute of Standards and Technology. Gaithersburg, MD, September.

Pitts, W. M., K. M. Butler, and V. Junker. 2005. Federal Building and Fire Safety Investigation of

the World Trade Center Disaster: Visual Evidence, Damage Estimates, and Timeline Analysis.

NIST NCSTAR 1-5 A. National Institute of Standards and Technology. Gaithersburg, MD,

September.

xxviii NIST NCSTAR 1-1J, WTC Investigation
Preface

Hamins, A., A. Maranghidcs, K. B. McGrattan, E. Johnsson, T. J. Ohlcmiller, M. Donnelly,

J. Yang, G. Mulholland, K. R. Prasad, S. Kukuck, R. Anleitner and T. McAllister. 2005. Federal

Building and Fire Safety Investigation ofthe World Trade Center Disaster: Experiments and

Modeling ofStructural Steel Elements Exposed to Fire. NIST NCSTAR 1 -5B. National Institute of

Standards and Technology. Gaithersburg, MD, September.

Ohlemiller, T. J., G. W. Mulholland, A. Maranghidcs, J. J. Fillibcn, and R. G. Gann. 2005. Federal

Building and Fire Safety Investigation ofthe World Trade Center Disaster: Fire Tests ofSingle

Office Workstations. NIST NCSTAR 1-5C. National Institute of Standards and Technology.

Gaithersburg, MD, September.

Gann, R. G., M. A. Riley, J. M. Repp, A. S. Whittakcr, A. M. Reinhom, and P. A. Hough. 2005.

Federal Building and Fire Safety Investigation ofthe World Trade Center Disaster: Reaction of

Ceiling Tile Systems to Shocks. NIST NCSTAR 1-5D. National Institute of Standards and

Technology. Gaithersburg, MD, September.

Hamins, A., A. Maranghidcs, K. B. McGrattan, T. J. Ohlemiller, and R. Anleitner. 2005. Federal

Building and Fire Safety Investigation ofthe World Trade Center Disaster: Experiments and

Modeling ofMultiple Workstations Burning in a Compartment. NIST NCSTAR 1-5E. National

Institute of Standards and Technology. Gaithersburg, MD, September.

McGrattan, K. B., C. Bouldin, and G. Foniey. 2005. Federal Building and Fire Safety

Investigation ofthe World Trade Center Disaster: Computer Simulation ofthe Fires in the World

Trade Center Towers. NIST NCSTAR 1-5F. National Institute of Standards and Technology.

Gaithersburg, MD, September.

Prasad, K. R., and H. R. Baum. 2005. Federal Building and Fire Safety Investigation ofthe World

Trade Center Disaster: Fire Structure Interface and Thermal Response ofthe World Trade Center

Towers. NIST NCSTAR I -5G. National Institute of Standards and Technology. Gaithersburg,

MD, September.

Gross, J. L., and T. McAllister. 2005. Federal Building and Fire Safety Investigation ofthe World Trade

Center Disaster: Structural Fire Response and Probable Collapse Sequence ofthe World Trade Center

Towers. NIST NCSTAR 1-6. National Institute of Standards and Technology. Gaithersburg, MD,

September.

Carino, N. J., M. A. Stames, J. L. Gross, J. C. Yang, S. Kukuck, K. R. Prasad, and R. W. Bukowski.

2005. Federal Building and Fire Safety Investigation ofthe World Trade Center Disaster: Passive

Fire Protection. NIST NCSTAR 1-6A. Nationallnstitute of Standards and Technology.

Gaithersburg, MD, September.

Gross, J., F. Hervey, M. Izydorek, J. Mammoser, and J. Treadway. 2005. Federal Building and

Fire Safety Investigation ofthe World Trade Center Disaster: Fire Resistance Tests ofFloor Truss

Systems. NIST NCSTAR 1-6B. National Institute of Standards and Technology. Gaithersburg,

MD, September.

Zarghamee, M. S., S. Bolourchi, D. W. Eggers, O. O. Erbay, F. W. Kan, Y. Kitane, A. A. Liepins,

M. Mudlock, W. I. Naguib, R. P. Ojdrovic, A. T. Sarawit, P. R Barrett, J. L. Gross, and

NIST NCSTAR 1-1J, WTC Investigation XXIX
Preface

T. P. McAllister. 2005. Federal Building and Fire Safety Investigation ofthe World Trade Center

Disaster: Component, Connection, and Subsystem Structural Analysis. NIST NCSTAR 1-6C.

National Institute of Standards and Technology. Gaithersburg, MD, September.

Zarghamee, M. S., Y. Kitane, O. O. Erbay, T. P. McAllister, and J. L. Gross. 2005. Federal

Building and Fire Safety Investigation ofthe World Trade Center Disaster: Global Structural

Analysis ofthe Response ofthe World Trade Center Towers to Impact Damage and Fire. NIST

NCSTAR 1-6D. National Institute of Standards and Technology. Gaithersburg, MD, September.

McAllister, T., R. W. Bukowski, R. G. Gann, J. L. Gross, K. B. McGrattan, H. E. Nelson, L. Phan,

W. M. Pitts, K. R. Prasad, F. Sadek. 2006. Federal Building and Fire Safety Investigation ofthe World

Trade Center Disaster: Structural Fire Response and Probable Collapse Sequence of World Trade

Center 7. (Provisional). NIST NCSTAR 1-6E. National Institute of Standards and Technology.

Gaithersburg, MD.

Gilsanz, R., V. Arbitrio, C. Anders, D. Chlebus, K. Ezzeldin, W. Guo, P. Moloney, A. Montalva,

J. Oh, K. Rubenacker. 2006. Federal Building and Fire Safety Investigation ofthe World Trade

Center Disaster: Structural Analysis ofthe Response of World Trade Center 7 to Debris Damage

and Fire. (Provisional). NIST NCSTAR 1-6F. National Institute of Standards and Technology.

Gaithersburg, MD.

Kim, W. 2006. Federal Building and Fire Safety Investigation ofthe World Trade Center

Disaster: Analysis ofSeptember II, 2001, Seismogram Data. (Provisional). NIST NCSTAR 1-6G.

National Institute of Standards and Technology. Gaithersburg, MD.

Nelson, K. 2006. Federal Building and Fire Safety Investigation ofthe World Trade Center

Disaster: The Con Ed Substation in World Trade Center 7. (Provisional). NIST NCSTAR I-6H.

National Institute of Standards and Technology. Gaithersburg, MD.

Averill, J. D., D. S. Mileti, R. D. Peacock, E. D. Kuligowski, N. Groner, G. Proulx, P. A. Reneke, and

H. E. Nelson. 2005. Federal Building and Fire Safety Investigation ofthe World Trade Center Disaster:

Occupant Behavior, Egress, and Emergency Communication. NIST NCSTAR 1-7. National Institute of

Standards and Technology. Gaithersburg, MD, September.

Fahy, R., and G. Proulx. 2005. Federal Building and Fire Safety Investigation ofthe World Trade

Center Disaster: Analysis ofPublished Accounts ofthe World Trade Center Evacuation. NIST

NCSTAR 1-7A. National Institute of Standards and Technology. Gaithersburg, MD, September.

Zmud, J. 2005. Federal Building and Fire Safety Investigation ofthe World Trade Center

Disaster: Technical Documentation for Swvey Administration. NIST NCSTAR 1-7B. NationalInstitute of Standards and Technology. Gaithersburg, MD, September.

Lawson, J. R., and R. L. Vettori. 2005. Federal Building and Fire Safet}> Investigation ofthe World

Trade Center Disaster: The Emergency Response Operations. NIST NCSTAR 1-8. National Institute of

Standards and Technology. Gaithersburg, MD, September.

XXX NIST NCSTAR 1-1J, WTC Investigation
Executive Summary

As part of the analysis of building and fire codes and standards of the National Institute of Standards and

Technology (NIST) World Trade Center (WTC) Investigation, this report supports the effort to document

the fuel oil distribution system located in WTC 7. Studies are under way to determine whether internal

fires may have led to the collapse. A possible factor to the collapse of WTC 7 was the fuel system for emergency power located throughout the 47-story building. The purpose of this report is to document the

fuel oil distribution system (including all fuel oil tanks, pumps, generators, routing of the piping, and

system functions) and the associated fire protection features of the fuel oil system that existed in WTC 7 on September 11, 2001.

The document search for this report located design drawings and specifications that were submitted to and

approved by the Port Authority of New York and New Jersey (PANYNJ or Port Authority) in accordance

to the Building Code of the City of New York (BCNYC) requirements. In addition to the above

documents, a set of certified as-built drawings for the Ambassador Construction project was located. WTC 7 contained two independently supplied and operated fuel systems for emergency power: the Base

Building system and the Salomon Brothers system. The Base Building system consisted of four subsystems: the Silverstein sub-system (original system), the Ambassador Construction sub-system, the American Express sub-system, and the Mayor's Office of Emergency Management sub-system. The

Ambassador Construction and American Express sub-systems were supplied with fuel from the original

Base Building storage tanks installed below the loading dock. The Mayor's Office sub-system contained

its own storage tank that was filled from the original system tanks. The other system (the Salmon

Brothers system), was supplied by a separate set of fuel storage tanks, also located below the loading

dock. The systems had differing design features with each system operating independently. The two

systems combined with all of the sub-systems, contained more than an estimated 43,000 gal of fuel,

assuming all tanks were filled near capacity. Since the owners had contracts with fuel delivery services to maintain the tanks full at all times, this assumption is considered reasonable.

E.1 BASE BUILDING SYSTEM

The Silverstein system was installed in 1987. The system contained two 12,000 gal capacity storage

tanks located below the 1st floor loading dock. The tanks supplied no. 2 diesel fuel to a duplex fuel oil pump set located in the 1st floor Fuel Oil Pump Room situated between the west banks of passenger

elevators. The pumps supplied fuel to a 275 gal capacity day tank' in the 5th floor Generator Room,

which supplied fuel to two 900 kW generators. The fuel oil return (FOR) pipes ran in parallel with the

fuel oil supply (FOS) pipes returning fuel back to the day tank and storage tanks.

In 1994, the Silverstein system was modified for the Ambassador Construction project. The Base

Building system was extended by tapping off the existing FOS pipe to the duplex pump set in the 1st floor

A day tank is a small-capacity fuel storage tank located near the generator(s) and kept full by a transfer pump from a mam

tank at or below grade. The BCNYC limits fuel supplies to no more than one 275 gal (maximum) day tank on any floor above the 1 st.

NISTNCSTAR 1-1J, WTC Investigation XXXI
Executive Summary

Fuel Oil Pump Room. The pump supplied fuel to the engine mounted day tank (50 gal capacity) of the 125 kW generator located on the 9th floor. The FOR pipe ran back to the existing FOR at the 1st floor.

Again in 1994, the Silverstein system was modified for the American Express project. The Base Building

system was extended by tapping off the existing FOS suction pipe and adding another duplex pump set in the 1st floor Fuel Oil Pump Room. A 275 gal day tank was added on the 8th floor, which supplied fuel to the 350 kW generator.

In 1999, the Silverstein system was modified for the Mayor's Office of Emergency Management project.

The system added two additional duplex pump sets. The 1st pump set was used to fill a new 6,000 gal

above ground storage tank on the 1 st floor. The second pump set was used to supply fuel from the new

storage tank to the new 275 gal day tank and three 500 kW generators on the 7th floor.

The four Base Building sub-systems were similarly designed, but were independently operated by the fuel pump set controllers for each system. The sub-systems included many similar devices, such as anti- syphon valves, foot valves, fusible link gate valves, solenoid valves, fuel level switches, rupture basins

and leak detectors, all performing specific operations. Although each sub-system was not designed

exactly like the other, the four sub-systems operated and performed similarly. Each sub-system operated

based on the liquid level in the day tanks. Each sub-system control panel (four total) started and stopped

the respective pump set by the liquid level switch in each day tank.

The various fuel devices listed above provided increased assurance that unwanted fuel discharge would

not occur. The devices listed above would have prevented, in most if not all scenarios, unwanted fuel discharge unto the floor below. The devices were installed to isolate fuel from open piping breaks,

prevent backflow and drainage of fuel unto the floor below and shut off the pump set to prevent fuel flow.

E.2 SALOMON BROTHERS SYSTEM

In 1990, a second fuel oil distribution system was installed for the Salomon Brothers project. The fuel for the system was supplied by two 6,000 gal storage tanks located under the loading dock. FOS pipes ran to the duplex pump set on the 1st floor. The FOS discharge pipes ran up to the 5th floor supplying fuel to nine 1,750 kW generators. The FOS discharge pipe ended at a valve rig where the FOR pipe started and

ran back to the pump set and storage tanks.

The Salomon Brothers fuel system had a similar but slightly different design than the Base Building

system. Similar to the Base Building system, the pump set provided fuel from two underground storage

tanks. However, there was already a day tank on the 5th floor associated with the base system and the BCNYC did not perniit more than one day tank per floor. Thus, the Salomon Brothers system used a continuously pressurized fuel supply piping system without a day tank. The fuel pressure in the FOS

discharge piping was maintained by a liquid level switch and back pressure regulator in the 5th floor valve rig. The liquid level switch started and stopped the pump set in accordance with the liquid level in the FOS discharge pipe. The pump was powered from the generators such that any time any one

generator was running, the pump was powered.

XXXll NISTNCSTAR 1-1J. WTC Investigation
Chapter 1 Introduction

World Trade Center (WTC) 7 collapsed on September 1 1, 2001. The collapse of WTC 7 is under study to deteraiine whether the internal fires on that day were probable causes for the building collapse. A

possible contributor to the fires within WTC 7 is the fuel oil distribution system for emergency power

located throughout the building. As part of the WTC 7 study, it is important to know where the fuel oil distribution components were located and to understand the system performance. The purpose of this report is to document the fuel oil distribution systems (including all fuel oil tanks, pumps, generators,

routing of the piping and system functions) and the associated fire protection features of the fuel oil system that existed in WTC 7 at the time of the collapse.

WTC 7, located between Vesey and Barclay streets and Washington Street West Broadway in New York

City, was an air rights building constructed over the existing two-stoiy Con Edison Substation. The

47-story building (constructed out of steel and concrete) underwent numerous modifications as tenants moved in and out of WTC 7. Certain tenants required emergency power for their operations. To

accommodate specific tenant requirements, the Base Building fuel oil distribution system was modified.

The original Base Building fuel system (Silverstein system) was installed in 1987. The system contained numerous components located from below grade to the 5th floor. In 1994 and 1999, the Base Building

system was modified three times to accommodate tenant requirements. Many components were added

and the system was extended up to the 9th floor. Also, in 1990, a second fuel oil distribution system was

installed for a multi-floor tenant (Salomon Brothers). The system was installed from below grade to the 5th floor. The following chapters describe in detail the fuel oil distribution system designs, layouts,

performances, and modifications.

The document search for this report located design drawings and specifications that were submitted to and

approved by the Port Authority of New York and New Jersey (Port Authority) in accordance with the Building Code of the City of New York requirements. In addition to the above documents, a set of

certified as-built drawings for the Ambassador Construction project was located.

Whenever work was done in the WTC buildings, a project number was assigned by the Port Authority

under which all contracts, drawings, and correspondence was filed. These numbers are typically of the format W(yy)-1234 (where yy is the year initiated and 1234 is a four-digit number). This report includes

these numbers as references to individual projects, and files retained by the Port Authority are identified by these numbers.

NISTNCSTAR 1-1J, WTC Investigation 1
Chapter 1

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2 NISTNCSTAR 1-1J, WTC Investigation
Chapter 2

Fuel Oil Provisions of the BCNYC

The facilities of the Port Authority of New York and New Jersey (PANYNJ) are not subject to the requirements of the local building codes, although PANYNJ policy was to follow the New York City

codes where applicable. The distribution system was to be designed to the provisions of the Building

Code of the City of New York (BCNYC). As previously stated, the fuel oil distribution systems were

installed in 1987 and 1990 with modifications occurring in 1994 and 1999. Generally, building

construction is performed to the most current code provisions at the time of installation. The code

provisions are often updated as technology and experience advance. However, between 1987 and 1999,

the fuel oil system provisions of the BCNYC remained unchanged. Thus, a single set of code provisions can be summarized for the initial design and the subsequent modifications. The BCNYC code provisions

used for the installations and modifications to the fuel oil distribution systems in World Trade Center

(WTC) 7 are listed in the remaining sections of this chapter.

2.1 GENERAL REQUIREMENTS

The hydrocarbon fuel oil used shall be as classified in Reference Standards (RS) 14-3 and RS 14-12 and

shall have a flashpoint not lower than 100 °F (27-827).'-

2.2 FUEL OIL STORAGE EQUIPMENT

All fuel oil storage tanks shall be built of steel plates or sheets, made by the open hearth or basic oxygen

process (27-828(a)(l)).

Tanks shall be welded, riveted and caulked, or riveted and welded. Flanges or other pipe connections

may be welded. Filler of any kind between plates shall be prohibited (27-828(a)(2)).

Tanks to be buried shall be cleaned and then coated on the outside with two coats of red lead, or

equivalent. Tanks shall be further protected by a coating of hot tar, asphah, or equivalent rust resistive material, applied at the work site. Tanks installed inside buildings above ground shall be coated with one

coat of red lead, or equivalent (27-828(a)(3)).

All buried storage tanks shall be constructed of at least Va in. thick metal and shall be designed to withstand any external loads to which the tank may be subjected (27-828(a)(4)).

Shop fabricated storage tanks shall be installed without structural alteration (27-828(a)(5)).

All openings shall be through the top of the storage tank (27-828(a)(6)).

' The fuel oil used in WTC 7 was no. 2 fuel oil.

" The BCNYC references given, denoted by 27-XXX, is the new numbering system.

NISTNCSTAR 1-1J, WTC Investigation 3
Chapter 2

Tanks for no. 2 commercial grade oils need not have manholes. However, if manholes are used for such

oils, the manhole covers shall be bolted and made gastight (27-828(a)(7)).

Tanks shall be located at least 7 ft, measured in the most direct manner, from any source of exposed flame

unless protected as provided in 27-829(a)(2) or 27-829(a)(3) and at least 2 ft from any surface where the temperature exceeds 165 °F (27-828(a)(9)).

Cylindrical tanks, except vertical tanks above ground outside of buildings, of more than 275 gal capacity

shall be constructed as follows (27-828(b)):

1 . Tanks 36 in. in diameter and less - at least in. shell and 'A in. heads.

2. Tanks 37 to 72 in. in diameter - at least Va in. shell and 5/16 in. heads.

3. Tanks 73 to 120 in. in diameter - at least 5/16 in. shell and 3/8 in. heads.

4. Tanks over 120 in. in diameter shall be of at least 3/8 in. steel and shall be stiffened by angle

rings or equivalent members so as to retain their cylindrical form.

All oil storage tanks of 275 gal capacity or less that are not buried shall have a minimum thickness of

shell and head plates of no. 10 manufacturer's standard gauge steel plate. Storage tanks of 60 gal capacity or less shall be similarly constructed but need not be thicker than no. 14 manufacturer's standard gauge

(27-828(d)).

2.3 LOCATION OF TANKS

Inside of buildings, above ground, on the lowest floor as follows (27-829(a)):

1. Storage tanks having a capacity of 550 gal or less may be installed above ground on the lowest floor of a building, provided that such tanks are mounted on adequate noncombustible

supports, with the tank anchored thereto. No more than 550 gal of total storage capacity may

be connected to one burner or may be installed without the protection provided in paragraph

27-829(a)(2)or27-829(a)(3).

2. Storage tanks having a capacity of more than 550 gal but less than 1,100 gal may be installed above ground on the lowest floor of a building, provided that all portions of such tanks above

the floor are completely enclosed with noncombustible construction having at least a 2 h fire resistance rating. Weep holes 1 in. in diameter shall be provided at least every 3 ft along the bottom of the enclosure unless at least 15 in. of clearance, together with access door, is provided between the tank and the enclosure.

3. Storage tanks having a capacity of 1 ,100 gal or more may be installed above ground on the lowest floor of a building, provided that all portions of such tanks above the floor are completely enclosed with noncombustible construction having at least a 3 h resistance rating.

At least 15 in. clearance shall be provided over the tanks and on all sides between the tanks

and the enclosure. A noncombustible access door, constructed so as to preserve the integrity

of the fire resistive enclosure, shall be installed in the enclosure above the point where the

4 NISTNCSTAR 1-1J, WTC Investigation
Fuel Oil Provisions of the BCNYC

capacity of the enclosure below the door sill would be equal to the capacity ot the largest lank

installed. When the longest inside dimension of the enclosure exceeds 35 ft, access doors

shall be installed at intervals not exceeding 12 ft. Columns, pipes, or similar obstructions

may project into the required 15 in. of space within the enclosure, provided that access door

or doors are so arranged that all portions of the enclosure are accessible for servicing.

4. The capacity of individual storage tanks in no case shall exceed 20,000 gal.

Inside of building above the lowest floor as follows (27-829(b)):

1. Fuel oil storage tanks having a capacity of 275 gal or less may be installed inside of buildings

above the lowest story when provided with a 4 in. thick concrete or masonry curb, or with a metal pan of gauge equal to the gauge of the tank, completely surrounding the tank and of

sufficient height to contain two times the capacity of the tank. The number of such oil storage tanks shall be limited to one per story.

2. Storage tanks having a capacity of 275 gal or less, installed above the lowest floor inside a building shall be filled by means of a transfer pump supplied from a primai^y storage tank

located and installed as otherwise required. A separate transfer pump and piping circuit shall be provided for each storage tank installed above the lowest floor. No intemiediate pumping

stations shall be provided between the storage tank and the transfer pump. Appropriate

devices shall be provided for the automatic and manual starting and stopping of the transfer pumps so as to prevent the overflow of oil from these storage tanks.

3. A float switch shall be provided with the curb or pan around the storage tank and shall be

arranged so as to sound an alann and stop the transfer pump in case of failure of the tank or

the control in the tank. The operation of the float switch shall be tested at least once each

week. An alarm bell shall be located in the same room with the tank and a visual and audible

alann shall be located in a maintenance office.

Inside of buildings, below ground as follows (27-829(c)):

1. Storage tanks having a capacity greater than 275 gal may be buried inside a building provided

that the top of the tank is at least 2 ft below floor level. In lieu of 2 ft of earth over the tank, the tank may be covered by concrete flooring having the same thickness as the basement

floor, but not less than 4 in. concrete and reinforced with 2 in. by 2 in. mesh of at least no. 20

U.S. standard gauge steel wire. Tanks shall be placed in firm soil and shall be surrounded by

clean sand or well-tamped earth, free from ashes and other corrosive substances, and free from stones that will not pass through a 1 in. mesh. When necessary to prevent floating,

tanks shall be securely anchored.

2. No tank shall be buried within 3 ft of any foundation wall or footing.

Outside of building, below ground as follows (27-829(d)):

1 . Storage tanks located outside of buildings and below ground shall be buried with the top of

the tank at least 2 ft below ground. Tanks shall be placed in firm soil and shall be surrounded

NISTNCSTAR 1-1J, WTC Investigation 5
Chapter 2

by clean sand or well-tamped earth, free from ashes or other coiTOsive substance, and free from stones that will not pass through a 1 in. mesh. When necessary to prevent floating,

tanks shall be securely anchored.

2. No tank shall be buried within 3 ft of any foundation wall or footing.

2.4 PIPING

Exposed piping shall be protected against mechanical damage and shall be adequately supported with

rigid metal fasteners or hangers. All pipes connected to buried tanks, except test well piping, shall be

provided with double swing joints at the tank (27-830(a)(l)).

Only new wrought iron, steel, or brass pipe, or type K or heavier copper tubing, or aluminum alloy

tubing, properly identified, may be used. Metal tubing when used for conveying oil shall be adequately

protected. Such tubing may be installed at the burner without protection. Drawn tubing when used in domestic installations shall be of at least 3/8 in. inside diameter up to the shut-off valve at the burner.

Soldered connections shall be prohibited (27-830(a)(2)).

Overflow pipes, where installed, shall not be smaller in size than the supply pipe (27-830(a)(3)).

Where a shut-off valve is installed in the discharge line from an oil pump, a relief valve shall be installed

in the discharge line between the pump and the 1st shut-off valve (27-830(b)(l)).

A relief or pressure regulating valve shall be provided in the oil piping system on the heater side of the shut-off valves (27-830(b)(2)).

Relief valves shall be set to discharge at not more than one and one-half times the maximum working

pressure of the system. The discharge from relief valves shall be returned to the storage tank or to the supply line. There shall be no shut-off valve in the line of relief (27-830(b)(3)).

Fuel oil heaters shall not be mstalled within the steam or water space of a boiler. Fuel oil heaters and the connecting piping shall be arranged to prevent oil leakage from being transmitted to the boiler. This may

be accomplished by any of the following methods (27-830(c)):

1 . By discarding the condensate from the heaters.

2. By using approved double tube or other approved heaters.

3. By means of a secondary hot water or steam heating system where the water or steam from

the boiler has no direct contact with the oil heater.

4. By a sight tank arrangement for collecting and inspecting the condensate which is provided

with a pump controlled by a hand switch for returning the condensate to the normal return system.

5. By such other method as may be permitted by the commissioner.

6 NISTNCSTAR 1-1J, WTC Investigation
Fuel Oil Provisions of the BCNYC

A vent pipe of iron or steel, without trap, draining to the tank, shall be provided for each storage tank. The lower end of the vent pipe shall not extend more than 1 in. through the top of the storage tank. Cross- connection between a vent pipe and fill pipe is prohibited (27-830(d)(l)).

Where a battery of storage tanks designed to hold the same grade of oil is installed, vent pipes may be run

into a main header (27-830(d)(2)).

Vents shall be at least one and % in. in diameter for storage tanks not exceeding 1,100 gal capacity and at least 2 in. in diameter for storage tanks of 1,100 gal or more except that vents for storage tanks of 60 gal

capacity or less shall be at least Vz in. in diameter. Vents for tanks inside of buildings above the lowest

floor shall be run into the primary storage tank vent (27-830(d)(3)).

Vent pipes shall be provided with an approved weatherproof hood having a free area of at least the pipe

size area. Vent pipes shall temiinate outside the building in a non-hazardous location, at least 2 ft from

any building opening and not less than 2 ft nor more than 12 ft above the fill pipe terminal, unless

otherwise permitted by the commissioner. If the vent pipe terminal is not visible from the fill pipe

temiinal location, a 1 in. tell-tale line shall be connected to the tank and shall parallel the fill pipe and

temiinate at the fill pipe temiinal with an unthreaded end. Such tell-tale lines shall be provided with a check valve set to prevent flow of surface water to the storage tank (27-830(d)(4)).

Fill pipes shall temiinate outside the buildings, with the fill pipe temiinal located at or above grade, at least 2 ft from any building opening and 5 ft from any subway grating at or below the level of the fill pipe

temiinal. No fill pipe shall be less than 2 in. in diameter. Where there are facilities for the delivery tank

tmck to drive onto the premises, the fill terminal may be located elsewhere than at the curb

(27-830(e)(l)).

Each storage tank shall be provided with a separate fill pipe, except that where a battery of tanks is installed containing the same grade of oil, a common fill and header pipe may be installed (27-830(e)(2)).

Where the top of the storage tank is above the fill pipe terminal, the fill pipe shall be connected to the top

of the tank and provided with a shut-off valve and swing check valve both of which shall be located at the

fill pipe terminal. However, the shut-off and check valves may be installed in an accessible location

inside the building at or below the level of the fill pipe temiinal (27-830(e)(3)).

All fill pipe terminals shall be of an approved type, and shall be provided with lugs for embedding in concrete. In lieu of lugs, a set screw or threads to fasten the tenninal to the fill pipe may be used

(27-830(e)(4)).

Piping from transfer pump to storage tanks above the lowest floor as follows (27-830(f)):

1 . The piping from a transfer pump to storage tanks at levels above the lowest floor in buildings, the return piping, and vent piping shall comply with the applicable provisions of subdivisions

27-830(a) and 27-830(d) and shall be enclosed in a shaft constructed of 4 in. concrete or masonry having a 4 in. clearance from all pipe or pipe covering. Provision shall be made for expansion in piping without the use of expansion joints.

NISTNCSTAR 1-1J, WTC Investigation 1
Chapter 2

2. Where it is necessary to make horizontal offsets in the supply piping and pipe shafts such

piping shall be enclosed in a sleeve of other piping of at least no. 1 0 manufacturer's standard

gauge steel, two sizes larger and arranged to drain into the shaft. Horizontal piping offsets

shall be further enclosed in construction having a 2 h fire resistance rating.

3. A drain pipe shall be installed at the base of shafts enclosing the supply and overflow piping.

The pipe shall lead to an open sight drain or to an open sump.

4. Oil lines for tanks above the level of the lowest floor shall be seamless steel pipe of a weight

not less than ASA schedule 40 with welded connections.

5. Pipe shafts shall not be penetrated by or contain other piping or ducts.

The heating of oil in storage tanks shall be by means of coils using low pressure hot water or steam, or by

means of electric heaters approved for use in oil storage tanks (27-830(g)).

Where more than one storage tank is connected to a common supply line, a shut-off valve shall be

provided in the supply line at each tank. Where more than one burner is connected to a supply line a shut- off valve shall be provided at each burner. Where a single tank and a single burner are installed, a shut- off valve shall be required in the supply line at the tank and another at the burner. Valves shall be brass

or equivalent in corrosion and fire resistance, shall provide tight shut-off, and shall be rated at 125 psi or

greater as required by the pressure in the system (27-830(h)(] )).

Where a storage tank is located so that the top of the tank is above the oil inlet to the burner or to the fuel pump, and the storage tank capacity is greater than 275 gal, the supply line to the burner shall be provided

with an approved anti-syphon device. The device shall be located at the highest point in the supply line. Where an approved foot valve is used in the tank and the tank is constructed with a manhole, an anti- syphon device shall not be required (27-830(h)(2)).

The pressure in oil lines to burners located above the lowest floor of a building shall not be more than is required to circulate oil to and from the burners, and all parts of the oil system shall be capable of

withstanding the maximum working pressure in that part of the system (27-830(h)(3)).

A remote control shall be provided to stop the flow of oil to any burner. Such control shall be located

outside the entrance to the room in which the burner is located and as close to such entrance as

practicable, except that when an outside location is impracticable, such control may be located

immediately inside the room in which the burner is located, provided such location is accessible at all times. On storage tanks of 60 gal or less capacity used with manually operated burners, such remote

control may be installed in the supply lines between tank and burner (27-830(h)(4)).

Pressure in a storage tank for the purpose of discharging oil shall be prohibited (27-830(h)(5)).

In systems where either steam or air is used for atomizing the oil, the oil and the atomizing supply shall be interlocked so that where the supply of either is interrupted, the supply of the other will be

immediately cut off (27-830(h)(6)).

8 NISTNCSTAR 1-1J, WTC Investigation
Fuel Oil Provisions of the BCNYC

All tanks located inside buildings shall be provided with an oil level indicating device. Test wells shall be

prohibited in tanks located inside of buildings. Unused tank openings shall be permanently sealed to prevent the removal of plugs or cover (27-830(i)( 1 )).

Oil level indicating devices shall be designed and constructed of substantial materials so that there can be no leakage of oil or oil vapor (27-830(i)(2)).

Test wells in storage tanks located outside of buildings shall be capped oil tight and kept closed when not

in use (27-830(i)(3)).

2.5 CONTROLS

With each automatic burner a set of safety controls of the electric, pneumatic, hydraulic, or mechanical

type shall be installed and maintained in good working order. The controls shall provide the following

functions (27-831):

1 . Ignition

2. Stack or combustion control

3. High temperature or pressure control

NISTNCSTAR 1-1J. WTC Investigation 9
Chapter 2

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10 NISTNCSTAR 1-1J, WTC Investigation
Chapter 3

Base Building Design (1987)

The Base Building fuel oil system (Silverstein system) design was submitted to the Port Authority of New

York and New Jersey (PANYNJ) for approval in 1987 under PANYNJ submittal number W-01437. The

system was designed by the development team of:

• Owner/Developer: Silverstein Properties, Inc.

• Architect: Emery Roth & Sons, P.C.

• Structural Engineer: The Office of Irwin G. Cantor, P.C.

• Engineer: Syska & Hermessy

3.1 BASIC LAYOUT

The fuel distribution system was designed for no. 2 diesel fuel. The design started with two storage tanks

located below the 1st floor loading dock located on the south side of the building (Fig. 3-1). The storage

tanks were connected with a 2 in. fuel oil supply (FOS) pipe leading to a duplex fuel oil pump set located

at the north wall of the 1st floor Fuel Oil Pump room which was located between the two west banks of

passenger elevators. The fuel was pumped via a 2 in. FOS pipe to a 275 gal day tank located on the north

wall of the 5th floor Generator Room, which was located at the west end of the south wall (Fig. 3-2). The

2 in. FOS pipe, which led to the day tank, ran vertically up a shaft near the west bank of passenger

elevators. The shaft where the FOS pipe was located also contained other building utilities. The day tank

supplied fuel to two emergency generators located on the east wall of the 5th floor Generator Room. A

2 in. fuel oil return (FOR) pipe, ran parallel with the FOS pipe back to the day tank. The FOR pipe

continued back to the pump sets and storage tanks. An elevation diagram showing the floor locations of

components is provided as Fig. 3-3.

3.2 COMPONENT DETAILS

The two Silverstein storage tanks had a capacity of 12,000 gal each. Each storage tank had a fuel fill box

at grade and was specified to be constructed of fiberglass reinforced plastic.

The fuel oil pump set consisted of a strainer and two positive displacement pumps specified for 3/4 hp.

The pump schedule on the drawings listed the pumps as 4.4 gpm at 3,500 rpm with a design pressure of

50 psi. Each pump had a relief valve set at 100 psi. The pump set was designed to have the lead pump

start and stop automatically in response to the level controller in the day tank. A hand oil pump was also

to be installed in parallel with the pump set. The hand oil pump was specified as a multiple-acting

oscillating force type pump with a capacity of 30 gpm at not more than 50 double strokes per minute.

The FOS discharge piping also contained a check valve.

NISTNCSTAR 1-1J, WTC Investigation 11
Chapter 3

The 275 gal day tank was equipped with a high-level alarm, pump on, pump off, and low-level alann.

The tank was specified to be equipped with a double-throw selector switch for active pump selection. Level controls were to automatically start the pump set at the low level and stop the pump set at the highlevel settings to maintain oil supply in the day tank. Alann actuators were programmed to sound an alarm

when the oil level in the tank fell below the low-level pump cut-in setting or rose above the high-level

pump cutout setting. The day tank supply line (FOS discharge line) had a solenoid valve installed. The

day tank sat inside a 550 gal capacity collecting pan. The collecting pan contained an alarai device to detect fuel and a drainpipe with a capped off valve. The collecting pan had a high-level pump cutoff and

alann set to automatically stop the pump set and sound an alarm when the oil reached the high-level

setting in the collecting pan. The day tank also had a fuel oil vent pipe that tenninated outside of the south Generator Room wall.

The two generators were specified for 900 kW, 460 V, 3 phase and equipped with automatic engine

starting controls and alarms. Alann indicators included:

• Low and high oil pressure ^

'

,

• High cooling water temperature

• Low wann-up jacket water temperature

• Day tank low and high fuel level ^. .

• Low battery voltage

• Over speed

• Failure to start

The Silverstein FOS and FOR pipes were contained in an outer pipe that protected the fuel pipe. The

outer pipe was joined with welded flanges and oil tight gaskets. The outer pipe was covered with 2 in. calcium silicate (or equivalent) to provide a 2 h fire resistance rating. The outer pipe contained 1 in. couplings with inspection plugs located approximately 50 ft on center. The outer pipe contained inner

pipe support spiders approximately 10 ft on center. The high points of the FOS suction pipe were

equipped with anti-siphon valves.

3.3 FIRE PROTECTION

Sprinkler drawings indicate that the Mechanical Equipment Rooms were to be protected with a wet pipe

sprinkler system designed for ordinary hazard group I with a minimum density of 0.16 gpm/ft" over

1,500 ft" with a maximum spacing of 130 ft' per head.

Sprinkler drawings indicate that the Fuel Oil Pump Room was to be protected with a dry pipe sprinkler

system designed for ordinary hazard group III with a minimum density of 0.21 gpm/ft' over the entire room with a maximum spacing of 1 30 ft" per head. The drawings show a sprinkler main entering into the room but hydraulic design criteria and the location of sprinkler heads are not shown. The 5th floor Generator Room did not contain an automatic fire suppression system.

12 NISTNCSTAR 1-1J, WTC Investigation
Base Building Design (1987)

The drawings do not indicate the construction type of the Fuel Oil Pump Room. The door had a fire rating of 1 Vi h.

The Generator Room appears to have been constructed of 8 in. sohd concrete block. The fire rating of the walls was not indicated on the drawings. The fire rating of the Generator Room doors was 1 h.

3.4 REFERENCES

Emery Roth & Sons, P.C. 1 986. "7 World Trade Center." Architectural Drawings ( 1 , 3, 6, 1

1 ).

Emery Roth & Sons, P.C. 1987. "7 World Trade Center." Electrical Drawings (E-3, E-1 1, E-23, E-24).

January 30.

Emery Roth & Sons, P.C. 1987. "7 World Trade Center." Fire Protection Drawings (PFP-1, PFP-2).

January 30.

Emery Roth & Sons, P.C. 1987. "7 World Trade Center." Mechanical Drawings (H-2, H-6, H-22, H-24,

H-25).

Port Authority of New York and New Jersey. 1997. Port Authority Facility Condition Sun'cy Program,

7 World Trade Center. April.

Silverstein Properties. Equipment and Maintenance List, 7 World Trade Center.

Syska & Hennessy, Mechanical and Electrical Systems. 1984. 7 World Trade Center Specifications,

Section 15520 - Emergency Diesel Generator Systems. October 29.

Syska & Hennessy, Mechanical and Electrical Systems. 1984. 7 World Trade Center Specifications,

Section 16007 - Diesel Engine Driven Standby Power Plant. October 22.

NISTNCSTAR 1-1J, WTC Investigation 13
Chapter 3

Figure 3-1. Base Building 1st floor fuel oil distribution plan.

Figure 3-2. Base Building 5th floor fuel oil distribution plan.

14 NISTNCSTAR 1-1J, WTC Investigation
Base Building Design (1987)

9TH FLOOR

8TH FLOOR

7TH FLOOR

6TH FLOOR

;MERGENCy GENERATOR

TYP. OF 2) DAY TANK x

5TH FLOOR

4—

4TH FLOOR

3RD FLOOR

2ND FLOOR

1ST FLOOR

PUMPSEl

-t>-

STORAGE TANKS

CD CD'

Figure 3-3. Base Building section plan of fuel oil distribution components.

NISTNCSTAR 1-1J, WTC Investigation 15
Chapter 3

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16 NISTNCSTAR 1-1J, WTC Investigation
Chapter 4

Ambassador Construction Modification (1994)

The Ambassador Construction project occurred in 1994. The project entailed modifying the existing

Silverstein system. New fuel oil devices were added to the 1st and 9th floors and connected to the existing system on the 1st floor. The design was submitted to the Port Authority of New York and New

Jersey (PANYNJ) for approval as submittal W94-7 176.02. The design was developed by the team of:

• Consuhing Engineer: GC Eng. & Associates, P.C.

• Milo Kleinberg Design Associates, Inc.

4.1 BASIC LAYOUT

The design called for an additional fuel oil pump set located on the north wall of the existing Fuel Oil

Pump Room (Fig. 4-1). The 2 in. fuel oil supply (FOS) pipe for the new pumps was supplied from the suction side of the Silverstein pump set. The fuel oil was pumped up a new 1 'A in. riser located in a new

2 h fire resistance rated shaft dedicated for the fuel oil distribution system. The shaft was constructed out of 4 in. masonry and was located at the south end of the center bank of passenger elevators. The riser supplied fiiel to the engine mounted day tank of the emergency generator located on the southwest wall of

the 9th floor Mechanical Equipment Room (MER) (Fig. 4—2). The MER was located at the northwest comer of the building. An 1 % in. fuel oil return (FOR) pipe ran parallel with the FOS pipe from the generator back to the 2 h shaft and then increased in size to 2 in., which returned to the existing FOR pipe

of the Silverstein system. A drip pan was installed at the base of the 2 h shaft. The drain of the drip pan

emptied into an environmental oil collection tank located at the west wall of the 1st floor Fuel Oil Pump

Room. An elevation drawing showing the floor levels of components is provided as Fig. 4-3.

4.2 COMPONENT DETAILS

The fuel oil pump set included a strainer and two pumps specified for 145 gph, 100 psi, 1,725 rpm, and

460 V, 3 phase. The specified model was LO-104A by Preferred Utilifies (BSA Approval #412/48-SA).

The relief valve was set at 125 psi. The pumps were energized from the float control lever of the emergency generator day tank. A time delayed flow switch in the FOS discharge pipe of the pump set was designed to start the lag pump should the lead pump fail to maintain flow to the day tank. The

strainer was specified as model 50, manufactured by Preferred Utilities. The maximum pressure drop

specified was less than 1 Vi in. of mercury.

The transfer pipes (FOS and FOR) were of the same double wall design as the Silverstein system. The

inner fuel oil pipes were specified as seamless schedule 40 black steel. The outer contairmient pipes were

specified as 10 gauge welded steel pipe. The piping located outside of the generator room, pump room

and vertical masonry shaft was required to be insulated. Details show the pipe located outside the shaft to be enclosed with a 2 h fire rated venniculite. A shaft detail contains a note to coordinate the risers with

the fiiture FOS piping of the American Express distribution system. Details also indicate the FOR riser to

NISTNCSTAR 1-1J, WTC Investigation 17
Chapter 4

be shared with American Express. An lYi in. outlet on the 8th floor was installed in the FOR riser for the

future American Express system.

The 9th floor emergency generator was shown as 125 kW, 265/460 V, 3 phase. The engine mounted day

tank had a capacity of 50 gal and had a 100 gal capacity rupture basin surrounding it.

The drip pan at the base of the masonry shaft consisted of a 2 in. pipe leading to a 20 gal open sight

environmental collecting drum/tank. A leak detector was located at the base of the fuel oil riser in the double wall supply pipe drip leg and in the open sight drum. The detectors were specified as model RBS,

manufactured by Preferred Utilities-Rimcor Instruments.

The 9th floor Generator Room of the Ambassador Construction project was protected with a wet pipe

automatic sprinkler system. The Generator Room was protected with five sprinkler heads being supplied

by three branchline pipes. There is no mention of heating provisions for the wet pipe sprinkler system in the Generator Room. No hydraulic design criteria was given for the sprinkler system. The spacing of the sprinkler heads in the Generator Room appears to be 130 ft" or less. The branchlines appear to be of the same pipe sizes as the remaining 9th floor sprinkler system that is most likely designed to Light Hazard

pipe schedule: 2 heads on 1 in. pipe, 3 heads on 1 % in. pipe, and 5 heads on IVi in. pipe. The branchlines were supplied from a IVi in. looped main that was connected to only the existing east stair standpipe.

The Ambassador Construction Generator Room was enclosed with gypsum board walls consisting of

three 5/8 in. 20 gauge metal studs spaced at 16 in. on center and two layers of 5/8 in. fire code C gypsum

board on each side. The wall was filled with 3'/2 in. unfaced batt insulation. The wall extended from slab

to slab and was perimeter caulked on both sides at top and bottom. There were three doors to the Generator Room. All three doors were building standard 1 3/4 in. thick hollow metal doors. No fire ratings were given for the walls and doors.

GC Eng. & Associates, P. C. 1994. "Ambassador Construction Project." Architectural Drawings (A-5,

A-15,A-16). September 9.

GC Eng. & Associates, P.C. 1994. "Ambassador Construction Project." Electrical Drawings (E-1, E-3,

E-9). August 24. GC Eng. & Associates, P.C. 1995. "Ambassador Construction Project." Fire Protection Drawings

(SP-2). March 8. GC Eng. & Associates, P.C. 1995. "Ambassador Construction Project." Mechanical Drawings (H-2,

H-4, H-5, H-6, H-9). March 8.

4.3 FIRE PROTECTION

4.4 REFERENCES

18 NISTNCSTAR 1-1J, WTC Investigation
Ambassador Construction Modification (1994)

Figure 4-1. First floor fuel oil distribution plan after the Ambassador Construction

modification.

Figure 4-2. Ninth floor fuel oil distribution plan after the Ambassador Construction

modification.

NISTNCSTAR 1-1J, WTC Investigation 19
Chapter 4

/ NEW EMERGENCY GENERATOR

/ WITH ENGINE MOUNTED TANK

9TH FLOOR

8TH FLOOR

7TH FLOOR

6TH FLOOR

EXiSTtNG SALOMON BROTHERS ; DISTRSBUTiON SYSTEM

/

rrj ^

/

5TH FLOOR

EXISTING BASEBULDih: 4TH FLOOR

3RD FLOOR

\ NEW PUMP SE'i 2ND FLOOR

1ST FLOOR

Figure 4-3. Section plan of fuel oil distribution components after the Ambassador

Construction modification.

20 NISTNCSTAR 1-1J, WTC Investigation
Chapter 5

American Express Modification (1994)

The American Express modification occurred at or around the same time as the Ambassador Construction

project in 1994. Provisions for the American Express fuel oil distribution system are noted in the Ambassador Construction drawings. The project included fuel oil distribution changes to the Silverstein

system located on the 1st, 7th, and 8th floors. The design was submitted to the Port Authority of New

York and New Jersey (PANYNJ) for approval under PANYNJ submitted number W93-7233. The project

team included:

• Architect: Gensler & Associates Architects

• Mechanical/Electrical Consulting Engineer: Lehr Associates

5.1 BASIC LAYOUT

The American Express design started in the 1st floor Fuel Oil Pump Room by tapping into the existing 2 in. fuel oil supply (FOS) suction pipe of the Silverstein system. The new 2 in. FOS pipe supplied fuel

to a new pump set located at the west wall of the 1st floor pump room (Fig. 5-1). A new 2 in. FOS pipe

ran up the same 4 in. masonry shaft as the Ambassador Construction project to a day tank located in the 8th floor (Fig. 5-3) Generator Room on the west side of the building. The day tank was connected to the emergency generator. A 2 in. fuel oil return (FOR) pipe from the day tank penetrated the Generator

Room floor and then continued back horizontally to the masonry shaft on the 7th floor (Fig. 5-2). The

FOR pipe went back to the existing 2 in. FOR pipe located in the 1st floor Fuel Oil Pump Room. An

elevation diagram showing the floor location of components is provided as Fig. 5^.

5.2 COMPONENT DETAILS

The American Express fuel oil pump set consisted of a strainer and two '/2 hp pumps. The drawings

specified Preferred Utilities pump Model 02715 or approved equal (BSA #1396-24SA) with a rating of

170 gph at 100 psi. The pumps had Vi in. relief valves piped back to the existing FOR pipe. A fuel oil pump controller was located at the day tank to automatically and manually start/stop the pump set. The

controller was equipped with a high-level probe to automatically stop pumps and sound an alann to prevent an overflow.

The pipes were specified as schedule 40 seamless. All horizontal piping above the lowest level was

installed in an outer containment pipe two sizes larger than the inner fuel oil pipe. The horizontal pipes were installed in a 2 h fire resistance rated enclosure.

The day tank had a capacity of 275 gal. The day tank was set in a rupture basin that contained leak

detection, which was to sound an alarm when liquid was detected.

The eight-floor emergency generator was shown as 350 kW, 438 kVa. and 60 Hz.

NISTNCSTAR 1-1J, WTC Investigation 21
Chapter 5

A detail in the drawings indicated a 14 gauge pan to be installed at the base of the masonry shaft. The

pan was connected by a IV2 in. drainpipe to a 50 gal open basin with a liquid detector. The basin was shown at the east wall of the 1 st floor Fuel Oil Pump Room.

5.3 FIRE PROTECTION

The American Express Generator Room on the 8th floor was protected by an automatic wet pipe sprinkler

system. The hydraulic design criteria for the floor indicates a system design for Light Hazard with a density of 0.10 gpm/1,500 ft'. Hydraulic calculations were perfomied with a sprinkler head K factor of

5.62 and a sprinkler head spacing of 120 ft'. There were five sprinkler heads in the Generator Room

supplied by three branchline pipes. The sprinklers in the Generator Room were spaced at approximately

80 ft". The branchline sizes of the Generator Room were sized to match the calculated sizes of the remaining office floor: 1 head on 1 in. pipe, 3 heads on Wa in. pipe, and 5 heads on IV2 in. pipe. The

brachlines were supplied from a IVz in. looped main that was connected to only the existing east stair standpipe.

It is not clear which partition type was used to enclose the Generator Room. Drawing 8A2.1 indicates

that all walls were to be Type A, unless otherwise noted. Type A walls were gypsum walls that consisted

of 21/2 in. metal studs spaced at 16 in. on center and one layer of 5/8 in. gypsum board on each side. The

gypsum board appears to have been extended only to the ceiling, not to the underside of the structure. Type A appears to have no fire resistive rating. It is apparent that the walls around the Generator Room

are thicker than the standard Type A walls on drawing 8A2.1. Also, looking more closely at the drawing,

small hash marks are apparent along the Generator Room walls suggesting that a wall type other than

Type A was to be used in the design. Drawing A9.4 indicates a wall Type H that may have been used for the Generator Room walls. Type H is a 2 h rated wall consisting of 6 in. concrete masonry unit, filled with grout and one layer of 5/8 in. gypsum board on 7/8 in. hat channel on one side of the wall. The Type

H detail on A9.4 also shows a 4 in. high concrete pad adjacent to the wall. The concrete pad further suggests that a Type H wall was used for the Generator Room since the generator sat on a concrete pad

against the wall. The double doors to the Generator Room were fire rated for 1 V2 h and had smoke seals

at the sills.

5.4 REFERENCES

Gensler & Associates Architects. 1994. "American Express 7 World Trade Center, NYC." Architectural

Drawings (A0.3, A9.1, A9.2, A9.4, 8A2.1). March 14.

Gensler & Associates Architects. 1994. "American Express 7 World Trade Center, NYC." Electrical Drawings (E0.3). July 26.

Gensler & Associates Architects. 1994. "American Express 7 World Trade Center, NYC." Fire

Protection Drawings (8-SP 1.2). March 16.

Gensler & Associates Architects. 1995. "American Express 7 World Trade Center, NYC." Mechanical

Drawings (MO.4.2, 7-Ml.l, 8-M1.2). February 24.

22 NISTNCSTAR 1-1J, WTC Investigation
American Express Modification (1994)

FUEL OIL PUMP SET

CORE

I II I

I II I —TT—

Figure 5-1. First floor fuel oil distribution plan after the American Express modification.

Figure 5-2. Seventh floor fuel oil distribution plan after the American Express

modification.

EMERGENCY GENERAT

FUEL OIL RETURN

RISER

FUEL OIL SUPPLY

RISER

Figure 5-3. Eighth floor fuel oil distribution plan after the American Express

modification.

NISTNCSTAR 1-1J, WTC Investigation
Chapter 5

9TH FLOOR

V — NEW EMERGENCY GENERATOR

8TH FLOOR NEW DAY imi

j

7TH FLOOR

6TH FLOOR

EXiSTiKiG „>u.u-v!0:-v HER.: DtSTRIBUTION SYSTEM

u:::>

EXiSJiHG AMBASSADOR CONSTRUCTION

DiSTRISUTION SYSTEM

5TH FLOOR

4TH FLOOR

3RD FLOOR

2ND FLOOR

-. NEW PUMP SET

1ST FLOOR

i ij! !

- EXiSTiNG BASE BULDiNG

DSSTRiBUTiON SYSTEM

r

Figure 5-4. Section plan of fuel oil distribution components after the American Express

modification.

24 NISTNCSTAR 1-1J, WTC Investigation
Chapter 6

Mayor's Office of Emergency Management

Modification (1999)

In 1999, the last modification to the Silverstein system was perfonned to accommodate the Mayor's

Office of Emergency Management (OEM) in World Trade Center (WTC) 7. The design of the fuel oil distribution system was very demanding. The specifications required a design to self-support OEM

operations for at least one week. Modifications were made at the 1st and 7th floors. The design was

submitted to the Port Authority of New York and New Jersey (PANYNJ or Port Authority) for approval

under PANYNJ submittal number W98-7 1 34. The modification was performed by the following team:

• Architect: Swanke Hayden Connell

• Mechanical Engineer: Cosentini Associates, L.L.P.

• Structural Engineer: The Cantor Seinuk Group, P.C.

• Construction Manager: Ambassador Construction Co., Inc.

6.1 BASIC LAYOUT

A fill pump set was connected to the suction side of the existing pump set in the existing Fuel Oil Pump

Room (Fig. 6-1). The Fuel Oil Pump Room contained an alarm drum (catch basin for fuel leakage) with

leak detection. An 1 '/4 in. fuel oil supply (EOS) pipe was connected from the fill pump set to a new

storage tank located in the existing Televator Room (storage room for battery operated Genie boom lift) between the center and east passenger elevator banks on the 1st floor. An 1 Va in. FOS pipe was run back

from the storage tank to an additional transfer pump set in the Fuel Oil Pump Room. From the transfer pump set, a VA in. FOS pipe was connected to the existing FOS riser (it is unclear which existing riser was being referred to, although drawings reference the existing riser being previously approved in submittal number 94-7176 to the PANYNJ). From the 7th floor FOS existing riser, a new VA in. FOS

pipe was connected to a day tank at the north wall of the 7th floor Generator Room located on the south

side of the building (Fig. 6-2). The Generator Room was classified as Building Code of the City of New

York (BCNYC), D-2 Industrial (Low Hazard). The day tank connected three emergency generators using

VA in. FOS pipes. A VA in. fuel oil return pipe ran from the generators back to the day tank. An

elevation diagram showing the floor location of components is provided as Fig. 6-3.

The addition of the new storage tank mandated a fire separation from the existing Televator Room. The

separation was accomplished by creating an isolated mezzanine that supported the new storage tank in the Televator Room.

NISTNCSTAR 1-1J, WTC Investigation 25
Chapter 6

6.2 COMPONENT DETAILS

The fill pump set consisted of a strainer and a pair of 2 hp pumps specified for 2,000 gph, 1,140 rpm,

50 psi total head, 125 psi design pressure, 460 V, 3 phase. The pump was specified as LO-207,

manufactured by Preferred Utilities. A relief valve was installed in the FOS discharge pipe. The pump

was electrically interlocked with the existing transfer pumps to prevent simultaneous operation.

The transfer pump set consisted of a strainer and a pair of 3/4 hp pumps specified for 700 gph, 50 psi total head, 125 psi design pressure, 460 V, 3 phase. The pump was specified as LO-203, manufactured by

Preferred Utilities. A relief valve was installed in the FOS discharge pipe. On a drop in the fuel level below the low level, the lead pump started and stopped when it reached the high level. Should the lead

pump fail to supply sufficient flow to the day tank, the fluid level would drop to low-low level control and start the lag pump and sound an alarm. The lag pump was to stop when the level reached high-level

control. An alami was designed to sound at a high-high level.

All fuel oil pipes outside of the Fuel Oil Pump Room and Fuel Oil Tank Room were 10 gauge conduit

and in a 2 h fire rated enclosure. A swing check valve was installed in the supply hne of the pump. An

anti-siphon valve was installed at the high points of the FOS suction pipe.

The alann drum in the Fuel Oil Pump Room had a capacity of 50 gal and contained a leak detection

assembly model TG-EL-D3 manufactured by Preferred Utilities.

The OEM day tank had a capacity of 275 gal and contained a 550 gal rupture basin. The day tank was

supplied with two high-level switches wired in-line for safety. If the 1st switch failed to shut down the transfer pump, the second switch's contact was to open and, in turn, shut down the transfer pump, close the solenoid valve and alarm the Building Management System.

The three 7th floor emergency generators were specified as 500 kW, 625 kVA, 480/277 V, 3 phase. A

safety interlock was installed to prevent operation of the emergency generator if discharge plenum access was open for service or inspection. The emergency generators were equipped with alarnis for in operation, low starting batteries, and emergency shutdown.

The OEM fuel oil storage tank had a capacity of 6,000 gal. The tank was equipped with alanns for lowlevel, high-level, and leakage/rupture. A solenoid valve was installed in the FOS discharge piping close

to the tank. The tank sat on a new structure in the Televator Room constructed specifically for the new

storage tank. The new structure was of 4 h fire rated construction and was completely enclosed, with

exception to an access hatch. Documentation of the submittal to the PANYNJ indicates that the location,

design, and protection of the storage tank were a major issue with the Port Authority, mostly related to an

original request to locate the tank on the 7th floor near the generator. This request was denied by New

York City Fire Department because the BCNYC does not permit storage tanks above the 1st floor except

for small (>275 gal) day tanks. Some important facts that come from the PANYNJ submittal documents

include designating the Fuel Oil Tank Room as BCNYC occupancy classification A with the Televator

Room below as occupancy classification B-2-Storage. The Fuel Oil Tank Room was to have retaining

walls and curbs for leakage.

26 NISTNCSTAR 1-1J, WTC Investigation
Mayor's OEM Modification (1999)

6.3 FIRE PROTECTION

The 7th floor OEM Generator Room did not contain a suppression system but contained smoke detectors. All of the existing sprinkler piping and heads were removed under the scope of the project. The new

1st floor Fuel Oil Tank Room was protected with an Inergen System. The modification project included

adding sprinkler coverage to the Televator Room below. The sprinkler system for the Televator Room

was designed to high hazard with a maximum spacing of 100 ft" per head. The sprinkler heads were

spaced at 168 ft" per head. The modification project also included removing the existing sprinkler heads

and branchlines from the Fuel Oil Tank Room. Although sprinkler lines were removed, standpipc and

hose rack piping remained in the Fuel Oil Tank Room. All of the electrical devices in the Fuel Oil Tank

Room were explosion proof, suitable for BCNYC hazardous location classification Class 1, Division 1, Group C.

As previously mentioned, the Fuel Oil Tank Room was enclosed in a 4 h fire rated construction. The

walls were constructed of 8 in. concrete masonry unit. The tops of the walls were installed with

Thermafiber and sealant on both sides.

The Generator Room was enclosed in 2 h fire rated construction consisting of three 5/8 in., 25 gauge

metal studs spaced at 16 in. on center and had three layers of 5/8 in. gypsum board on both sides. The

gypsum board inside was water resistant. An 8 in. concrete curb was constructed at the perimeter of the Generator Room. The door to the Generator Room was fire rated for 1 1/2 h.

6.4 REFERENCES

Swanke Hayden Connell Ltd. 1998. "Mayor's Office of Emergency Management, 7 World Trade Center

Specification Manual." April 6.

Swanke Hayden Connell Ltd. 1999. "Mayor's Office of Emergency Management, 7 WTC NYC, NY."

Architectural Drawings ( A- 1 -

1 ) . August 2 3

Swanke Hayden Connell Ltd. 1998. "Mayor's Office of Emergency Management, 7 WTC NYC, NY."

Electrical Drawings (El.Ol, E1.07, E3.01, E6.01). September 25.

Swanke Hayden Connell Ltd. 1998. "Mayor's Office of Emergency Management, 7 WTC NYC, NY."

Fire Protection Drawings (FPl.Ol, FP2.07). September 25.

Swanke Hayden Connell Ltd. 1999. "Mayor's Office of Emergency Management, 7 WTC NYC, NY."

Mechanical Drawings (Ml.Ol, M1.07, M4.01). March 29.

NISTNCSTAR 1-1J, WTC Investigation 27
Chapter 6

Figure 6-1. First floor fuel oil distribution plan after the OEM modification.

Figure 6-2. Seventh floor fuel oil distribution plan after the OEM modification.

28 NISTNCSTAR 1-1J, WTC Investigation
Mayor's OEM Modification (1999)

9TH FLOOR

8TH FLOOR

7TH FLOOR

FROM EXISTING

/ RISER

NEW EMERGENCY

GENERATOR

(TYP. OF 3) -P czD

NEW DAY TANK

6TH FLOOR

EXISTING SALOMON BROTHERS

DISTRIBUTION SYSTEM /

4GS.

3UTI'

5TH FLOOR

EXISTING AMERICAN EXPRESS

DISTRIBUTION SYSTEM

EXISTING AMSASSADOR CONSTRUCTION

DISTRIBUTION SYSTEIVI p

4TH FLOOR

3RD FLOOR

EXISTING BASE BULDING

DISTRIBUTION SYSTEM!

2ND FLOOR

-TIE INTO EXISTING RISER

1ST FLOOR

.H<j:-~.

r

! r

f i

NEW TRANSFER

PUMP SET

fl

C J CD

NEV^- STORAGE

TANK

Figure 6-3. Section plan of fuel oil distribution components after the OEM modification.

NISTNCSTAR 1-1J, WTC Investigation 29
Chapter 6

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30 NISTNCSTAR 1-1J. WTC Investigation
Chapter 7

Salomon Brothers Addition (1990)

In 1990, Salomon Brothers added a new fuel oil distribution system, independent of the Base Building

system of World Trade Center (WTC) 7. The new fuel oil distribution system contained components

below the loading dock, the 1st floor and the 5th floor with vertical piping in between. The design was

submitted to the Port Authority of New York and New Jersey (PANYNJ) for approval as either PANYNJ

submittal number W-7004 or W-7005. The design team consisted of:

• Architect/Engineer: Skidmore, Owings & Merrill

• Mechanical/Electrical Engineer: Flack & Kurtz

• Structural Engineer: Office of Irwin G. Cantor, P.C.

7.1 BASIC LAYOUT

The fuel oil distribution system started with two storage tanks located beneath the loading dock just west

of the existing Silverstein storage tanks (Fig. 7-1). A 3 in. fuel oil supply (FOS) pipe ran to a Fuel Oil

Pump set located in a dedicated enclosure at the southeast comer of the existing Fire Pump Room located

at the southwest comer of the building. An emergency fuel oil fill and retum line was mn from the pump

set towards the central bank of passenger elevators and temiinated. The pump set was connected to nine

emergency generators via a 2I/2 in. FOS pipe. The FOS vertical riser was located just north of the pump

set. The emergency generators were located throughout the 5th floor (Fig. 7-2). Four generators were

located at the northeast comer of the building. Two generators were located at the northwest comer of the building. Three generators were located in the existing Generator Room next to the two existing

generators of the Silverstein system. The IVi in. FOS pipe temiinated at just beyond the last generator in the northeast comer and then a IVi in. fuel oil return (FOR) pipe retumed back to the storage tanks. An

elevation drawing showing the floor location of components is provided as Fig. 7-3.

7.2 component details

The two fuel oil storage tanks each had a capacity of 6,000 gal. They were of fiberglass construction and

each was provided with a vent whistle alarm.

The pump set consisted of a strainer and two IV2 hp pumps specified for 70 gpm, 50 psi total head,

1,150 rpm, 460 V, 3 phase. The specified model was 43D275 manufactured by Preferred Utilities.

The 3 in. FOS suction pipe from the storage tanks to the pump set was run underground. The 2Vi in. emergency FOS and FOR pipe from the pump set to the various generators were of the double walled

constmction type previously mentioned throughout the report. Calcium Silicate was used to provide the 2 h fire resistance rating.

NISTNCSTAR 1-1J, WTC Investigation 31
Chapter 7

The nine emergency generators were specified as 1,750 kW.

The end of the FOS pipe and beginning of the FOR pipe at the 5th floor contained a valve rig in a leak

proof box. The valve rig consisted of a backpressure regulator, gauges, and by-pass line. A liquid level switch was also installed in the vicinity. The liquid level switch was a model L6 EPB-B-S-3-H

manufactured by Dwyer. The liquid level switch was wired to the pump relay.

WTC 7 was sprinklered except for mechanical floors and generator and electrical rooms as exempted by

the Building Code of the City of New York and its Reference Standards.

Skidmore, Owings & Merrill. 1996. "Salomon Brothers Inc." Electrical Drawings (E-Rl). August 27.

Skidmore, Owings & Merrill. 1989. "Salomon Brothers Inc." Electrical Drawings (E-5). August 15.

Skidmore, Owings & Merrill. 1990. "Salomon Brothers Inc." Mechanical Drawings (HVAC- 1,

7.3 FIRE PROTECTION

7.4 REFERENCES

HVAC-1.1, HVAC-5, HVAC-54, HVAC-54.1, HVAC-55).

32 NISTNCSTAR 1-1J, WTC Investigation
Salomon Brothers Addition (1990)

Figure 7-1. First floor fuel oil distribution plan after the Salomon Brothers addition.

Figure 7-2. Fifth floor fuel oil distribution plan after the Salomon Brothers addition.

NISTNCSTAR 1-1J, WTC Investigation 33
Chapter 7

9TH FLOOR

8TH FLOOR

7TH FLOOR

6TH FLOOR

NEW EMERGENCY

GENERATOR

(TYP. OF 9)

5TH FLOOR

4TH FLOOR

3RD FLOOR

EXiSTiNG BASE BUI.DING DiSTRlBUTION SYSTEM

2ND FLOOR

NEW PUMP SET -~ -

1ST FLOOR

f

\

r~

1

i

f

^ - "

NEW STORAGE —

TANKS

; 3 (

Figure 7-3. Section plan of fuel oil distribution components after the Salomon Brothers

addition.

34 NISTNCSTAR 1-1J, WTC Investigation
Chapter 8

Final Configuration

World Trade Center (WTC) 7 contained two independent fuel oil distribution systems: the Salomon

Brothers system and the Base Building system. The two 12,000 gal Base Building fuel oil tanks provided

fuel to the two emergency generators on the 5th floor, which provided emergency power as required. The

Base Building fuel oil distribution system also provided fuel to the Ambassador Construction generator on the 9th floor, the American Express generator on the 8th floor and the three generators for the Mayor's

Office of Emergency Management on the 7th floor. The two 6,000 gal Salomon Brothers fuel oil tanks

provided fuel to the nine generators located on the 5th floor. The final configurations, as of

September 11, 2001, of the two fuel oil distribution systems in WTC 7 are represented in Figs. 8-1

through 8-6. The component locations are approximated from the design drawings submitted to the Port Authority of New York and New Jersey for approval. Floor plans not shown between the 1st and

9th floors contain fuel oil risers only. For more specific locations and details, see the documented

drawings listed in the Reference sections of each chapter of this report.

NISTNCSTAR 1-1J. WTC Investigation 35
Chapter 8

9TH FLOOR

8TH FLOOR o—czH

7TH FLOOR

, MAYOR'S OFFICE

DiSTRiBUTiON SYSTEM a]

(QTY. OF 3)

6TH FLOOR

SALOMON BROTHERS

DISTRIBUTION SYSTEM

[JZ>

iOTY OF 9)

5TH FLOOR

AMERICAN EXPRESS

DISTRIBUTION SYSTEM

AMBASSADOR CONSTRUCTION

DISTRIBUTION SYSTEM r-O—Lzri

4TH FLOOR

3RD FLOOR

2ND FLOOR

BASE BULDING

DISTRIBUTION SYSTEM

LEGEND O DAY TANK I |]

( ) STORAGE TANK1 ^ [—

EMERGENCY GENERATOR

PUMP SET

Figure 8-1. Section plan showing the final locations of the fuel oil distribution

components.

36 NISTNCSTAR 1-1J, WTC Investigation
Final Configuration

Figure 8-3. Final location of 5th floor fuel oil distribution components.

NISTNCSTAR 1-1J, WTC Investigation 37
Chapter 8

Figure 8-4. Final location of 7th floor fuel oil distribution components.

Figure 8-5. Final location of 8th floor fuel oil distribution components.

38 NISTNCSTAR 1-1J, WTC Investigation
Final Configuration

Figure 8-6. Final location of 9th floor fuel oil distribution components.

NISTNCSTAR 1-1J, WTC Investigation
Chapter 8

\

This page intentionally left blank.

40 NISTNCSTAR 1-1J, WTC Investigation
Chapter 9

System Performance

9.1 BASE BUILDING FUEL OIL DISTRIBUTION SYSTEM

The Base Building fuel oil distribution system in World Trade Center (WTC) 7 was composed of four sub-systems, all having the same basic design: the Silverstein system, the Ambassador Construction

system, the American Express system, and the Mayor's Office of Emergency Management system. The

fuel oil supply to each of the four sub-systems was supplied by the sub-grade storage tanks installed in the

original Base Building design. However, the fuel oil pump set of each sub-system was independently

regulated by a separate control panel (four total). Each fuel oil pump set was designed to start and stop

the fuel oil supply as detemiined by the oil level in the respective day tank.

Details for all system components have not been identified from the available WTC documents and thus

the functions of the components can only be assumed through brief design comments on the drawings,

manufacturer's product applications, and an understanding of the typical operation of the various

components. Although each sub-system was not identical to the other, each system had the same basic

design and many similar components; see Fig. 9-1 for typical locations. Ahhough some components were not indicated in the design, it can be assumed that these components were installed due to the Building Code of the City of New York (BCNYC) requirements and/or basic understanding that the system would not perfomi without it. See Table 9-1 for a listing of each fuel oil device included in each

sub-system design. The following sections discuss the probable functions and components installed in each sub-system.

9.1.1 Liquid Level Switches/Detectors and Collecting Pans/Rupture Basins

As previously stated, the duplex transfer pump set was programmed to operate based on the liquid level of

the day tank. Each duplex pump set had a control panel located next to the pump set and/or next to the day tank that regulated the functions of the system. Each system was equipped with at least one liquid level switch in the day tank'. The liquid level switch(es) would turn the pump set on and off according to the level of fuel in the day tank. Upon detection of a low level in the day tank, the lead pump of the duplex pump set is started. Once the day tank is filled to the high level, the lead pump is stopped. In the event the lead pump is unable to provide sufficient flow to the day tank, the lag pump is started and

operates until the high level is achieved, which stops the pump set.

The day tanks were installed in rupture basins to prevent unwanted fuel discharge from the day tank. The

rupture basins installed had capacities of twice the capacity of the day tank. Most if not all of the rupture

basins contained a leak detector to further assure that fuel would not continue to flow from a ruptured day

tank. If a leak detector was present (most likely scenario since it is required by BCNYC), the system

would send an alarm to the Building Management System and stop the pump upon detection of fuel in the

The Ambassador Construction project refers to a liquid control lever. Whether this was a single float switch or multiple

switches, the lever would have been capable of starting and stopping the pump set according to the fuel level.

NISTNCSTAR 1-1J, WTC Investigation 41
Chapter 9

mpture basin. If a leak detector was not present in the day tank rupture basin (not likely), then it would

be possible to endlessly pump fuel onto the floor where the day tank is located until the selected storage

tank was emptied. The only other scenario that could endlessly pump fuel onto the floor where the day

tank is located would occur in the event of a break in the fuel oil supply (FOS) piping down stream of the day tank. This break could allow the day tank to reach a low level and start the pump set. Fuel would

flow onto the floor where no fuel detection is present until the storage tank that was selected was emptied.

It is unsure how likely this would be, understanding that lack of fuel to the generators would produce lack

of power to the pump set.

Leak detectors at the base of the FOS riser and in the collecting pans helped prevent the unwanted flow of

fuel. In the event of a break of the FOS discharge piping, the pump set would not start pumping fuel until the low level in the day tank was detected. Thus a break in the FOS discharge piping before a low level

in the day tank was detected would not start the pump set. However, if a low level in the day tank was

detected and the pump set started, and then a break occurred, there is a possibihty that fuel would flow

out the break in the pipe. But, it is also likely that the fuel would flow back down the outer pipe of the double wall piping construction to the base of the FOS riser and into the open sight fuel oil collecting pan

where leak detectors are installed. The leak detector, upon detection of fuel, would stop the pump set and

send an alarai to the Building Management System. Fuel would not likely flow endlessly out the break in the pipe.

There is another scenario that should be evaluated. The electrical wiring of the system should be

analyzed. It may have been possible to have an electrical malfunction in the system and have the pump

set start, with the possibility of pumping fuel endlessly out a pipe break. But, because the point to point

wiring schematic of the control panel showing the connection of all the electrical devices has not been

located, this scenario could not be evaluated.

9.1.2 Fusible Link Gate Valve

The fusible link gate valves included in the sub-system designs serve as an automatic shut off valve in the event of a fire. As the heat of the fire, within the room the valve is located, rises to the melting point of

the fusible link, the link melts, the valve closes and the fuel flow in the FOS pipe is shut off. At this point, fuel flow is stopped until the gate valve is manually re-opened.

9.1.3 Anti-siphon Valve and Check Valve

Fuel systems that included an anti-siphon valve were protected from fuel siphoning from the storage tanks

to the Fuel Oil Pump Room floor. Some designs included an anti-siphon valve installed at the highest

point of the FOS pump suction piping (between the storage tanks and the pump set). The anti-siphon

valve was installed to prevent the fuel in the storage tank from emptying onto the Fuel Oil Pump Room

floor in the event of a pipe break. An anti-siphon valve opens as negative pressure is applied downstream

of the valve. A pump creates enough negative pressure in the suction piping to open the valve, whereas, a pipe break in the suction piping does not create a sufficient amount of negative pressure to open the valve. But, siphoning of the fuel in the storage tanks was not likely to occur since the storage tanks were lower

m elevation than the Fuel Oil Pump Room floor.

42 NISTNCSTAR 1-1J, WTC Investigation
System Performance

The only other siphoning situation that could occur in the Fuel Oil Pump Room would be siphoning from

a day tank back to the Fuel Oil Pump Room. The anti-siphon valve would not be effective for this piping

break, but siphoning may or may not occur for two other reasons. The FOS pipe leading to a day tank is connected at the top of the tank and most likely does not extend inside to the bottom of the tank. If the connection does not extend to the bottom of the tank, the air gap between the day lank fuel and the FOS

pipe would eliminate the possibility of siphoning the fuel in the day tank to the Fuel Oil Pump Room

floor. However, if the connection extended to the bottom of the tank, then siphoning could occur. Second, there are check valves in the pump set piping that prevent backflow of fuel. If the break occurred

upstream of the check valve, no fuel would siphon back to the Fuel Oil Pump Room. Although, if the break occuired downstream of the check valve, siphoning may or may not occur, depending on the connection of the FOS piping to the day tank as stated above.

9.1.4 Foot Valve

The purpose of a foot valve was to keep the FOS pump suction piping primed with fuel and prevent the

fuel from draining back to the storage tanks. A foot valve is similar to a check valve, but is supposedly more efficient than a check valve at keeping the line primed.

9.1.5 Pressure Relief Valve

The FOS pump discharge piping of every sub-system contained a relief valve that prevented excessive

pressures from building up in the discharge piping. It is possible to build up excessive pressure in the pump discharge piping when a control valve or solenoid valve is closed and the pump set is on. The relief valve would prevent the pressure from rising above the predetermined relief valve setting by discharging

fuel into the fuel oil return (FOR) pipe until the pressure decreased to below the setting. The designs had

the pressure relief valve set to 100 psi to 125 psi.

9.1.6 Solenoid Valve

Most systems, if not all, had a solenoid valve located in the FOS pump discharge piping. The purpose of

the solenoid valve in the FOS pump discharge piping was to prevent unwanted fuel discharge to the day

tank. The solenoid valve was most likely programmed to close in an alann situation. The Silverstein

system required the solenoid valve to close on high level alann in the day tank. This would prevent an overflow or continuous flow of fuel through the FOS pump discharge piping. It is unclear whether the solenoid valve was normally in the closed or open position.

9.1.7 Tank Selector Valve

A tank selector valve was installed in the Silverstein system. The switch was used to switch the fuel supply from one tank to the other. The valve was manually operated and only pennitted one storage tank

at a time to supply fuel to the pump set and day tanks. Thus, if the fuel in the primary tank was emptied,

either by normal usage or unwanted discharge, the tank selector valve would have to be manually

switched to the secondary storage tank to supply fuel to the pumps.

NISTNCSTAR 1-1J, WTC Investigation 43
Chapter 9

STORAGE 7 ANK | X J

DUPLEX PUMP SET

LEGEND

LINK LEVER GATE VALVE

ANTI-SYPHON VALVE r PRESSURE RELIEF VALVE

IN CHECK VALVE

til SOLENOID VALVE ^- TANK SELECTOR VALVE

FOS FUEL OIL SUPPLY FOR FUEL OIL RETURN

Figure 9-1. Typical layout of critical devices in Base Building sub-systems.

44 NISTNCSTAR 1-1J, WTC Investigation
System Performance

Table 9-1. Critical fuel oil devices installed in Base Bui ding sub-systems.

Fuel Oil Component Silverstein Ambassador

Construction

American

Express

Office of Emergency

Management

Fusible link gate valve - Installed in fuel oil supply pump suction piping

No Yes No No

Anti-syphon valve - Installed in fuel oil supply pump suction piping

Yes Yes Yes' Yes

Foot valve - Installed in fuel oil supply

pump suction piping

Unknown'' No No Yes

Check valve - Installed in fuel oil supply

pump suction piping

Yes Yes Yes Yes

Pressure relief valve - Installed in ftiel oil supply pump discharge piping

Yes Yes Yes Yes

Solenoid valve - Installed in fuel oil supply

pump discharge piping

Yes Yes Unknown'^ Yes

High level switch - Installed in day tank Yes Unknown'' Yes Yes

Low level switch - Installed in day tank Yes Unknown"^ Assumed Yes

Rupture basin - Installed around day tank Yes Yes Yes Yes

Fusible link gate valve - In fuel oil supply

between day tank and generator

Yes No No No

Leak detector - Installed in day tank rupture basin Yes Assumed Yes Assumed

Leak detector - Installed at base of fuel oil supply/fuel oil return riser Unknown"^ Yes Yes Yes

Leak detector - Installed in pump room

collecting drum

Yes Yes Yes Yes

Tank selector valve - Installed in pump

room collecting drum

Yes Yes^ Yes' Yes'

a. Included in the Silverstein system, which supplies fuel to the remaining three sub-systems.

b. The Ambassador Construction modification refers to an existing 2 in. foot valve in the fuel oil supply pump suction piping. It

is most likely from the Silverstein system installation.

c. Detailed piping schematic and specifications have not been identified.

d. Specifications indicate that the pump set is to be energized from the float control lever. Operation of this lever is unclear.

e. Riser details have not been located. Key: Yes. component shown on drawing or listed in design specification; No, component not shown on drawing or

specifications; Assumed, based on requirements in the BCNYC, specifications, system capabilities or manufacturer's recommendations, the component is likely to be installed, but not shown.

NISTNCSTAR 1-1J, WTC Investigation 45
Chapter 9

9.2 SALOMON BROTHERS FUEL OIL DISTRIBUTION SYSTEM

The Salomon Brothers fuel system had a similar but slightly different design in comparison to the Base

Building fuel system. See Fig. 9-2 for the location of the critical devices. Two underground storage

tanks supplied the duplex pump set with fuel. The fuel system was designed using a pressurized loop

rather than day tanks. The FOS side of the loop ended with a valve rig that was designed to start and stop

the fuel oil supply. The fuel supply was provided by a duplex pump set. Similar to the Base Building

system, if the lead pump of the duplex pump set was unable to provide sufficient pressure in the FOS

piping, the lag pump would start and operate until the high level was achieved.

The valve rig controlled the fuel supply pressure in the FOS piping. The liquid level switch in the valve

rig controlled the fuel oil supply in the FOS piping. Upon detection of a low fuel level in the FOS pipe, the pump set would start. Once the high fuel level was achieved, the pump set would stop. The back

pressure regulator (located just downstream of the liquid level switch) maintained the proper fuel pressure

in the FOS piping. If excessive pressure built up in the FOS piping, the back pressure regulator would

relieve the excessive pressure in the FOR piping which drained back to the storage tanks. In addition to the back pressure regulator in the valve rig, pressure relief valves on the FOS pump discharge piping were

installed to assure the proper pressure in the FOS piping.

A tank selector valve was not included in the design. Drawings indicate that gate valves were included in the FOS pump suction pipes. It is unclear whether the FOS and FOR pipes to each tank were opened,

allowing both tanks to supply fuel to the pumps or whether one set of valves were closed, allowing only one storage tank to supply fuel to the duplex pump set. Thus, it cannot be determined, based on the

available documentation, whether one or both tanks would have supplied fuel to the pump set in the event of nonnal operations or unwanted fuel discharge.

A solenoid valve was installed in the FOS pipe to each generator. Documentation does not indicate the nonnal position (open or closed) of the solenoid valve. The solenoid valve was most likely wired to be

closed when the pump was off and then open during the call for fuel to a particular generator. The

solenoid valve could have been wired to close upon a detection of high fuel pressure in the FOS piping.

The second scenario is not likely due to the presence of the back pressure regulator and pressure relief valve.

A check valve was installed in each FOR pipe from the generator to the FOR loop piping. The purpose of

the check valve was to prevent any backflow of fuel from the FOR piping to the FOS piping.

A collecting tank and second valve rig were installed in the pump room. The purpose of an FOS pump

suction valve rig is undetennined. The 55 gal collecting tank was connected to the FOR pipes and

contained a float switch inside. It is unclear whether the float switch was to notify the presence of fiiel or

that the tank was nearly full. It is also unclear whether the switch stopped the pumps from supplying fuel

to the FOS loop.

Based on the available documentation, the pressurized loop could have endlessly discharged fuel out of a broken FOS pipe. A break in the FOS pipe, between the pump set and FOS valve rig, could have

activated the pump set. In the event of a FOS pipe break, the fuel could have emptied out of the valve rig,

sending a low level signal to the pump controllers from the liquid level switch and starting the pump set. Fuel would have flowed out the break until the storage tank(s) were emptied. However, if the double

46 NISTNCSTAR 1-1J, WTC Investigation
System Performance

walled construction of the FOS piping was designed similar to that of the Base Building system, it could

have been possible that a leak detector switch would have shut off the pump set. This cannot be

determined from the available documentation. The electrical characteristics of the system arc unknown

and need to be analyzed to detennine if an electrical malfunction would have started or stopped the fuel pump set.

DUPLEX PUMP SET

STORAGE TANK STORAGE TANK

LEGEND r PRESSURE RELIEF VALVE N CHECK VALVE

SOLENOID VALVE

GATE VALVE BACK PRESSURE REGULATOR VALVE

LIOUID LEVEL SWITCH FOS FUEL OIL SUPPLY FOR FUEL OIL RETURN

Figure 9-2. Layout of critical devices in Salomon Brothers system.

NISTNCSTAR 1-1J. WTC Investigation 47
Chapter 9

9.3 SYSTEM CAPACITIES

Based on the documented drawings, the amount of fuel located in the WTC 7 on September 11, 2001, is approximated to be 43,284 gal, see Table 9-2. This quantity of fuel in WTC 7 is based on many

assumptions. It was assumed that all of the tanks were filled to capacity. The presence, or lack thereof,

of fuel is based on the system performance assumptions previously stated. For example, the FOR pipes were assumed to be empty, except for trapped sections of pipe. This is based on details in the design

drawings showing the pipes pitched to drain back to the storage tanks.

Table 9-2. Capacity of fuel oil components throughout WTC 7. Fuel Oil Component Fuel Capacitj' (gallons)

Salomon Brothers System

Storage tanks (two) 12,000

Fuel oil supply (storage tanks to fuel oil pump set) 22.5

Fuel oil supply (fuel oil pump set to valve rig) 146.1 Valve rig 34.9

Fuel oil return (valve rig to storage tanks) 19.9 Base Building System

Base Building storage tanks (two) 24,000

Fuel oil supply (storage tanks to Base Building pump sets) 31.7

Fuel oil supply (Ambassador Construction pump set to day tank) 22

Ambassador Constmction engine mounted day tank 50

Ambassador Construction fuel oil return (day tank to fuel oil pump

room) 1

Fuel oil supply (American Express pump set to day tank) 57.6 American Express day tank 275

American Express fuel oil return (day tank to fuel oil pump room) 2.1

Fuel oil supply (Base Building pump set to day tank) 26.2 Base Building day tank 275 Base Building fuel oil return (day tank to fiiel oil pump room) 2.1

Fuel oil supply (OEM fill pump set to OEM storage tank) 10.9 OEM storage tank 6,000

Fuel oil supply (OEM storage tank to OEM transfer pump set) 11.6

Fuel oil supply (OEM transfer pump set to OEM day tank) 16.9 OEM day tank 275

OEM fuel oil return (day tank to fuel oil pump room) 1.2 Common fuel oil return (fuel oil pump room to storage tanks) 2.1

Totals Salomon Brothers system 12,223.4 Base Building system 31.060.4 WTC 7 total capacity 43,283.8

48 NISTNCSTAR 1-1J, WTC Investigation
Chapter 10

Maintenance History

Documentation for the maintenance history of the two distribution systems could not be located. A

Silverstein document indicates the maintenance schedule of three generators and four fuel oil pumps.

There are also notes on upgrades for the same items. The only other maintenance history document found

is in an inspection report dated April 1 997, which indicates that the fuel lines in the 5th floor Generator

Room were missing pipe supports. The maintenance schedule for the Silverstein items as indicated in the

Silverstein document are as follows.

Table 10-1. Maintenance schedule of fuel oil pumps and generators.

Description Location Maintenance Schedule Upgrades

Generator 1 5th floor Generator Room Weekly, monthly,

semiannual, annual New load bank and

voltage regulator

Generator 2 5th floor Generator Room Weekly, monthly,

semiannual, annual New load bank andvoltage regulator Generator 9-1 9th floor USSS Weekly, monthly,

semiannual, annual New generator

Fuel Oil Pump 1 Fuel Oil Pump Room Weekly, quarterly,

semiannual

Fuel Oil Pump 2 Fuel Oil Pump Room Weekly, quarterly,

semiannual Tenant Fuel Oil Pump 1 Fuel Oil Pump Room Weekly, quarterly,

semiannual

New pump and controls

Tenant Fuel Oil Pump 2 Fuel Oil Pump Room Weekly, quarterly,

semiannual

New pump and controls

Source: Silverstein.

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