This Safety and Health Information Bulletin (SHIB)

is not a standard or regulation, and it creates no new

legal obligations. The SHIB is advisory in nature,

informational in content, and is intended to assist

employers in providing a safe and healthful workplace. The Occupational Safety and Health Act

requires employers to comply with safety and health

standards promulgated by OSHA or by a state with

an OSHA-approved state plan. In addition, pursuant to Section 5(a)(1), the General Duty Clause of

the Act, employers must provide their employees

with a workplace free from recognized hazards likely

to cause death or serious physical harm. Employers

can be cited for violating the General Duty Clause if

there is a recognized hazard and they do not take

reasonable steps to prevent or abate the hazard.

However, failure to implement any recommendations

in this SHIB is not, in itself, a violation of the General

Duty Clause. Citations can only be based on

standards, regulations, and the General Duty Clause.

U. S. Department of Labor

Occupational Safety and Health Administration

Directorate of Science, Technology & Medicine

Office of Science and Technology Assessment

SHIB 03-24-2008

Safety and Health Information Bulletin

Potential Flammability Hazard Associated with Bulk Transportation

of Oilfield Exploration and Production (E&P) Waste Liquids

Incident

On January 13, 2003, a vapor cloud ignited, leading

to a fire at an oilfield waste disposal facility (hereafter,

disposal facility) near Rosharon, Texas, south of

Houston. The fire occurred as two vacuum trucks

were off-loading liquid wastes from oil and gas

production wells.

The trucks arrived at the disposal facility within a few

minutes of each other and were parked approximately

16 feet apart. The two drivers got out of their trucks,

left the engines running, and told the disposal facility

employees that the trucks were to be drained and

rinsed out. Both drivers then went to the drivers’ shed

to complete paperwork and to wait for the washout to

be completed. (1)

The fire was caused by the ignition of hydrocarbon

vapor released during the off-loading of basic

sediment and water (BS&W) from the two vacuum

trucks into an open area collection pit. BS&W is an

oil/gas exploration and production (E&P) waste liquid.

The BS&W was contaminated with highly flammable

condensate. During the off-loading, vapor off-gassed

from the BS&W and was drawn into the air intakes of

the vacuum trucks’ running diesel engines. As a result,

the engines began to race and backfire. The

flammable vapor cloud ignited. (1)

The post-incident investigation documented five

possible vapor cloud ignition sources – the vacuum

trucks’ diesel engines, vacuum truck electrical systems,

static electricity discharge from the off-loading liquid,

(although equipped with a grounding cable, the trucks

were not grounded during the off-loading), personnel

smoking, and facility electrical wiring. The

investigation determined that the diesel truck engines

were most likely the ignition source based on physical

evidence and the supporting eyewitness testimony. (1)

Two disposal facility employees and one tank driver,

employed by the transport company, were killed in the

fire. Three other disposal facility employees and one

truck driver suffered severe burns. The fire destroyed

the two 50-barrel vacuum trucks (each tank truck =

2,100 gallon capacity) owned by the transport
2

necessary precautions to take to minimize the

generation of flammable vapor and to control

ignition sources,

• The importance for companies to obtain the

necessary material safety data sheets

(MSDSs) before transporting waste or

disposing of it,

• Employers’ obligations regarding hazard

communication and the safe handling of oilfield

and gasfield waste, and

• The responsibility of all employers to properly

train their employees in a manner clearly

company and heavily damaged waste liquid offloading equipment and structures at the facility (See

Figure 1). (1)

Purpose of SHIB

The purpose of this Safety and Health Information

Bulletin is to alert other facilities in the oil and gas

industry about:

• The potential flammability hazard associated

with BS&W and other E&P waste liquids,

• The safe work practices operators should

follow when handling and transporting

potentially flammable waste liquids, and the

Figure 1. Layout of Open Area, Gravity Feed, Disposal Pad, with Vacuum Trucks

Positioned as on January 13, 2003, When the Fire and Deflagration Occurred. (1)
understood by the recipients (all affected

personnel).

CSB Investigation

Because of the deaths and injuries caused by this

incident, OSHA and the U.S. Chemical Safety and

Hazard Investigation Board (CSB) conducted

investigations. CSB’s investigation sought to

determine the root and contributing causes, and to

issue recommendations to interested parties in an

effort to prevent similar occurrences. (1)

In its investigation report, the CSB pointed out that

“the oil and gas industry disposes of many thousands

of barrels of E&P waste liquids annually, including

potentially flammable BS&W.” (1) “E&P wastes can

have flammability characteristics that meet the

definition of a flammable liquid in both OSHA and

DOT regulations, thus posing a significant physical

hazard to personnel.” (1) The CSB found

inconsistency within the oil and gas industry in

managing the potential flammability hazard of BS&W.

In some cases, the flammability hazard is not

identified or recognized, and work practices are

inadequate for safe handling of the potentially

flammable liquid.

Root Causes

The CSB investigation revealed the following root

causes of this incident:

• The producer/shipper of the waste failed

to identify the flammability hazard of

BS&W generated at its gas well

production facility and also failed to

communicate the hazard to employees and

contractors who were required to handle

the flammable liquid (1),

• The transport company did not ensure that

the producer provided vacuum truck

drivers with a material safety data sheet or

other document listing the potential

flammability hazard of BS&W, nor did it

identify the flammability hazard of the

mixture in the vacuum trucks’ tanks (1),

and

• Management at the disposal facility did not

have effective hazard communication

practices in place to recognize the

potential flammability hazard of each

shipment of BS&W, nor did it implement

safe handling practices for off-loading

flammable liquid into the mud disposal and

washout pad area. (1)

Contributing Causes

Contributing causes of the incident reported by the

CSB are summarized below:

• The transport company did not understand

the potential flammability hazard of

BS&W in the product storage tanks, nor

did they understand that inadvertent mixing

of hydrocarbon product with waste liquid

when filling the vacuum trucks’ tanks most

likely increased the flammability hazard of

the trucks’ contents (1),

• The transport company and disposal

facility management did not implement safe

work practices to minimize the generation

of flammable vapor and to control ignition

sources (1), and

• Neither the transport company nor the

disposal facility management and

employees recognized that the trucks’

diesel engines presented multiple vapor

ignition sources. (1)

Discussion of Standards

Based on the listed root causes of this incident, the

following aspects of the incident and their associated

3
4

OSHA standards are identified below.

Hazard Determination and MSDSs

• Drillers and producers must evaluate

chemicals they produce to determine if

they are hazardous, i.e., determine the

potential flammability hazard associated

with BS&W and other E&P waste liquids

- 1910.1200(d).

• Drillers and producers must obtain or

develop appropriate MSDSs for the

hazardous materials they produce, i.e.,

BS&W – 1910.1200(g)(1).

• Drillers and producers must ensure that

appropriate MSDSs are provided to

downstream employers, e.g., the transport

company, with their first shipments –

1910.1200(g)(6)(i).

• The transport company did not conduct a

hazard determination or obtain an MSDS

from the producer. The transport

company is responsible for a hazard

determination of the hazardous chemicals

they deliver to downstream customers/

employers – 1910.1200(d)(1).

Training Information and Labelling

• Procedures implemented by employers at

workplaces to protect employees from

hazardous chemicals must be included in

the employer’s hazard communication

training for their employees and contract

employees. For example, in this case, the

producer was required to include

appropriate elements of hazard

communication training to the transport

company driver (contract employee), who

used the specified tank off-loading

procedure to drain the BS&W from the

producer’s tank. One basis for this

procedure was to prevent the draining of

lighter, presumably flammable

hydrocarbons into the transport

company’s vacuum truck, thereby

reducing the risk of a fire/explosion

incident. This same concept was

applicable at the disposal facility. The

specific procedures utilized at this facility

to protect employees from chemical

hazard exposures needed to be included

in the hazard communication training for

employees and contract employees –

1910.1200(h)(3)(iii). In this case, safe

practices were not implemented at this

disposal facility when the mixture in the

vacuum truck was by gravity drop offloaded to a concrete pad. As a result,

off-gassing from the condensate/BS&W

mixture formed a vapor cloud which

ignited and ultimately caused the employee

deaths and injuries as well as property

damage.

• All employee safety information must be in

languages and presented in a manner that

can be clearly understood by all affected

personnel – 1910.1200(h)(1). If the

employees receive job instructions in a

language other than English, then the

training and information provided needs to

be presented in that language.

• Storage tanks must be properly labeled to

clearly identify the hazard of the tanks’

contents to all employees and contractors

working at the wellsite and disposal facility

– 1910.1200(f)(5) and (6).

Work Procedures and Emergency Planning

• At the disposal site, management needs to

develop and implement written

procedures and provide training to

employees on off-loading all flammable or

potentially flammable BS&W and other

E&P waste liquids. Safe procedures need

to be followed when off-loading

flammable or potentially flammable liquids

from tank trucks, including methods to

minimize generation of flammable vapor.
*

 OSHA requires written emergency procedures [1910.120(q) or 1910.38(a)] except in the case where employers have ten or

fewer employees and chose to comply with the emergency action plan requirements of 1910.38.

• Ignition sources from vehicle-mounted

equipment and facility equipment need to

be controlled - 1910.106(e)(6)(i).

Ignition sources include those related to

vehicular and electrical equipment located

in hazardous classified areas.

• Emergency proceduresmust be

developed [1910.120(q)(1) or

1910.38(a)]* and training provided

[1910.120(q)(6) or 1910.38(e)] to

employees on responding to abnormal or

emergency situations, including

uncontrolled flammable vapor releases

that can result in a fire or explosion

hazard. Emergency procedures need to

address the safe response to abnormal

diesel engine operation (e.g., diesel engine

overspeed – “racing”) due to a flammable

vapor atmosphere being drawn into the

air intake system of the truck. It should

be noted that the normal engine shut-off

method will not suffice as long as

flammable vapor continues to enter the

intake system.

Vacuum Truck Operations

Vacuum truck owners must ensure that vacuum truck

operators are trained and qualified for their work

assignment. The following Standards address the

issues necessary to provide appropriate training.

 • 29 CFR 1910.1200, Hazard

Communication,

 • 29 CFR 1910.106, Flammable and

Combustible Liquids,

 • 29 CFR 1910.120, Hazardous Waste

Operations and Emergency Response,

 • 29 CFR 1910.307, Hazardous (classified)

Locations,

 • 29 CFR 1910.1000, Air Contaminants,

and

 • 49 CFR, Parts 171, 172, 173, 178, 179,

382, 383 and 390-397, U.S. DOT “Motor

Carrier Safety requirements for proper

hazard classification and manifesting of

flammable liquids, approved container design,

and periodic testing.

Recommendations

Hazard Materials Awareness

Vacuum truck owners must ensure that vacuum truck

operators are aware of the physical and chemical

characteristics of flammable, combustible, toxic and

corrosive materials. Trace amounts of flammable and

combustible liquids and gases, hydrogen sulfide gas,

acids, caustics, spent acids, sour water and other

liquids, materials and gases present in the petroleum

industry may cause serious injury, illness or death if not

properly handled. (2)

MSDSs need to provide correct information on

hazardous materials in tanks or vessels, but

occasionally, for various reasons, they do not

accurately reflect the hazards associated with comingled and waste products, tank bottoms,

contaminated catalysts, spent acids or other materials

that are being transferred. (2) Therefore, employers

should be aware that in these cases a flammable or

toxic hazard could exist even though its MSDS does

not identify this hazard

CSB found that the majority of those industry

personnel questioned during the investigation did not

believe that BS&W poses a flammability hazard, even

though it can contain highly flammable condensate.

“CSB analysis of nine tank BS&W samples from six

production wells, including one of the wells involved in

the BLSR incident, indicated flashpoints below 30oF in

eight of the samples. For comparison, the flashpoint of

condensate is about -36oF, and the flashpoint of

gasoline is about -45oF. OSHA classifies any liquid

5
6

with a flashpoint below 100oF as a flammable liquid.”

(1)

“Care must be taken to ensure that the materials being

loaded into the cargo tank are compatible with

materials previously loaded and that the mixing of

these materials will not create hazards such as fire,

explosion, heat, toxic gases or vapors. Unless the

vacuum truck has been thoroughly cleaned and

inspected, it should not be used to load materials

which are not compatible with those previously

handled.” (2) The same principles apply when the

cargo tank contents are off-loaded – the contents

must be compatible with the materials presently or

previously contained in the receiving container. (2)

Safe Vacuum Truck Operations

Vacuum truck owners and operators, as well as facility

personnel, should be aware of numerous potential

hazards associated with operating vacuum trucks in

petroleum facilities, including, but not limited to the

following:

• sources of ignition,

• potential hazards including spills,

flammable atmosphere within and around

vacuum trucks, cargo tanks or source

containers, hose failures, and discharges

of flammable vapors to the atmosphere,

• potential hazards associated with the

surrounding area and atmospheric

conditions during vacuum truck

operations, and

• toxic vapor build up at or near the vacuum

pump discharge port.

Note: An industry recognized good practice,

American Petroleum Institute (API) Publication No.

2219, provides safe vacuum truck operating guidelines

and a comprehensive checklist in an appendix. (2)

Atmospheric Testing

“The areas where vacuum trucks operate must be free

of hydrocarbon vapor concentrations in the flammable

range.” (2) “If there is any question of whether the

area is free of flammable vapor or toxic gas,

atmospheric testing must be performed by a qualified

person using properly calibrated and adjusted

combustible gas indicators, appropriate toxic gas

testers, or hydrocarbon analyzers. Testing should be

conducted anytime there is uncertainty about the

safety of the surrounding atmosphere, including prior

to starting any operation, and during operations.” (2)

Bonding and Grounding

“The complete vacuum transfer system should be

bonded to ensure a continuous conductive path from

the vacuum truck through the hose and nozzle to the

tank or source container.” (2) Bonding ensures that

there is no difference in electrostatic potential between

vacuum trucks and pumps and the source or receiving

tank, container or vessel. (2) “This reduces the

likelihood of a spark being created in the vicinity of

flammable vapors when the suction nozzle or

discharge hose is removed from the source or

discharge container and/or is disconnected from the

vacuum trucks, or when any conductive connectors

are disconnected.” (2)

Grounding is also a must. Prior to starting transfer

operations, vacuum trucks need to be grounded

directly to the earth or bonded to another object that

is inherently grounded (due to proper contact with the

earth), such as a properly grounded large storage tank

or underground piping. Grounding ensures that any

electrostatic charges that might be generated can be

“bled off” to the earth, bringing all parts of the system

to zero electrical potential. (2)

Personnel Safety

As stated earlier, vacuum truck personnel working in

petroleum facilities must be trained in the safe

operation of the vacuum equipment; be familiar with
7

the hazards of the petroleum products, byproducts,

wastes, materials being transferred, as well as any comingled wastes; and be aware of relevant government

and facility safety procedures and emergency

response requirements. (2)

MSDSs for the products being transferred must be

available to vacuum truck operators, and a qualified

person must be able to assess the potential exposure

to unsafe air contaminant levels as well as any

potential or existing flammable atmospheres. (2)

When loading and off-loading, all personnel must

leave the truck cab and shut off the engine if

flammable vapors are generated at or above 25% of

the Lower Explosive Limit (LEL). However, when

transferring flammable liquids or hazardous materials,

vacuum truck operators should stay within 25 feet of

the vacuum truck (between the truck and the source

or receiving tank, vessel, or container) throughout the

operation. (2) In practice, the vacuum truck

operators will be positioned upwind and to one side of

the truck within the line of sight of the operation.

Vacuum truck operators must monitor the transfer

operation and be ready to quickly close the product

valve and stop the pump in the event of a blocked line

or release of material through a broken hose or

connection. (2) Vacuum truck owners must develop

emergency procedures that conform with OSHA

requirements found in 29 CFR 1910.120 (q) and 29

CFR 1910.38 (a), and must train all vacuum truck

operators in the use of those procedures. In the event

of a fire, spill, release, or other emergency, operators

must be knowledgeable about emergency reporting

and appropriate emergency response actions.

During loading and off-loading, position the vacuum

truck on level ground, at least 25 feet away from (50

feet if in a diked area) and preferably upwind or

crosswind of the source or receiving tank, vessel, or

container. (2) Smoking must not be permitted within

at least 100 feet (depending on local procedures and

atmospheric conditions) of the truck, the discharge of

the vacuum pump, or any other vapor source. (2)

Conclusion

To prevent future accidents like this, the hazard of

exploration and production (E&P) waste liquids must

be recognized, communicated, and controlled by

employers in the oil and gas production industry. Oil

and gas waste liquids can be highly flammable and

need to be handled appropriately.

OSHA recommends that employers engaged in the

production, transport, and disposal of waste liquids

take the following action:

• Ensure that MSDSs on BS&W waste

material are provided to all haulers and

disposal facility operators so that endusers know what is being delivered,

• Ensure proper hazard classification and

manifesting of flammable liquids that are

being shipped,

• Develop written procedures for safe

unloading and handling practices of all

potentially flammable waste liquids,

designed to minimize vapor formation and

prevent static discharges that could ignite

vapors,

• Provide adequate training for all

personnel,

• Operate vacuum trucks in a safe manner

(refer to API Publication No. 2219),

• Perform atmospheric testing in

accordance with API Publication 2219,

Section 5.2, and

• Develop emergency procedures,

particularly when diesel engines overspeed

due to the presence of highly flammable

vapors.
References

1. U.S. Chemical Safety and Hazard Investigation

Board, Investigation Report: Vapor Cloud

Deflagration and Fire, 2003. Avaliable on-line at:

http://www.csb.gov/completed_investigations/docs/

BLSRFinalInvestigationReport.pdf

2. American Petroleum Institute, API Publication No.

2219, “Safe Operations of Vacuum Trucks in

Petroleum Service,” 2005.

Edwin G. Foulke, Jr.

Assistant Secretary

Occupational Safety and Health Administration

8