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vapors entering the control room through the pressurized under the wind condition that put the building itself at risk.”
air handling equipment. MGPI was also specifically cited for As explained in Section 3.1 and Section 5.4 of this Case Study,
not adequately addressing hazards related to facility siting. Mod B operators were forced to evacuate the building without
OSHA reasoned that “Employees were exposed to [a] release shutting down any other processes due to the toxic gas entering
of volatile organic compounds (VOC)s to atmosphere that the building through the vents directly adjacent to the tank
historically result in explosion, fire and health hazards leading farm and the lack of access to appropriate respirators.
95
to injury and death to employees in the workplace.” Had
the hazard of toxic vapors entering the control room been The Center for Chemical Process Safety (CCPS) Guidelines for

recognized prior to the incident, the ventilation system at Mod Facility Siting and Layout (2003) discusses control building siting
B may have been modified or designed to prevent ingress. and placement of building HVAC intakes. CCPS recommends
that vents and relief vents on equipment be located to vent to
Commonly referenced texts briefly cover positive pressure control a safe location, specifically a safe distance from building HVAC
rooms and ventilation systems. Lees’ Loss Prevention in the Process intakes. CCPS also suggests that consequence analyses
100
Industries (4th Edition) discusses the need for an airtight design, per API RP 752 be conducted to address potential toxic
positive pressure requirements, and the possible use of toxic impacts to control buildings. If the control building is shown

gas detectors and alarms in the control building that shut off to be impacted, mitigation measures, such as supplied air,
normal ventilation air. Design of control rooms for protection HVAC pressurization, or shutdown, should be provided.
96
101
against toxic releases is also discussed in the Chemical Industry
Association’s (CIA) Process Plant Hazard and Control Building 5.3.2 PREVIOUS RECOMMENDATION TO ASHRAE
Design (1979). Specifically it states, “Normal external ventilation Had the Mod B building and ventilation system been designed
97
air supplies, liable to prevent the infiltration of, or automatically respond to,

Evaluate building design to be contaminated, releases from the outdoor tank farm, operators likely would
have had more time to safely shut down processes, retrieve
must be capable
and ventilation systems of being sealed their emergency escape respirators, and evacuate. Because of
near chemical unloading off… [and] control the lack of U.S. standards and guidance for how to specifically
stations to ensure building occupants design building ventilation systems to protect against different

occupants are protected must be supplied in types of potentially hazardous chemicals from various sources, in
in the event of a spill or an emergency with 2005, at the conclusion of the Honeywell investigation, the CSB
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chemical reaction clean air for the length issued recommendation 2003-13-I-LA-R22 to the American
of the emergency Society of Heating, Refrigeration, and Air Conditioning Engineers
or alternatively (ASHRAE). The CSB recommended that ASHRAE “Develop guidance

98
for the time necessary to shut the plant down.” Alternatively, on the effective design and maintenance of HVAC systems and
CIA acknowledges that it may be possible for ducted air to be other necessary control room components designed to protect
supplied from a sufficient distance “that it is uncontaminated employees and equipment in the event of a release of hazardous

99 Chemical Industry Association. (1979). An approach to the categorization of process
95 OSHA Inspection 1186824, Citation 1 Item 7. This violation was amended in the plant hazard and control building design. London, England, 1979. Appendix III.6.
Informal Settlement Agreement and combined with the general PHA violation, 100 CCPS. Guidelines for Facility Siting and Layout. [Online] Center for Chemical Process
Citation 1 Item 6.
Safety/AIChE: New York, NY, 2003. http://app.knovel.com/hotlink/toc/id:kpGFSL0005/
96 Mannan, S. Lees’ Loss Prevention in the Process Industries, Vols. 1-3, 4th ed.; [Online]; guidelines-facility-siting/guidelines-facility-siting (accessed September 13, 2017).
Elsevier: Waltham, MA, 2012. http://app.knovel.com/hotlink/toc/id:kpLLPPIVH2/lees- 101 CCPS. Guidelines for Facility Siting and Layout. [Online] Center for Chemical Process
loss-prevention/lees-loss-prevention (accessed September 13, 2017).
Safety/AIChE: New York, NY, 2003. http://app.knovel.com/hotlink/toc/id:kpGFSL0005/
97 Chemical Industry Association. (1979). An approach to the categorization of process guidelines-facility-siting/guidelines-facility-siting (accessed September 13, 2017).
plant hazard and control building design. London, England, 1979.
102 Recommendation Status Change Summary, 2003-13-I-LA-R22. http://www.csb.
98 Chemical Industry Association. (1979). An approach to the categorization of process gov/assets/recommendation/Status_Change_Summary__ASHRAE_(Honeywell_
plant hazard and control building design. London, England, 1979. Appendix III.6. R22)__O-ARAR1.pdf (accessed September 13, 2017).
26 CSB MGPI Processing Case Study