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Jul 14, 2014

Ensuring Public Protection From Toxic Gas Releases

The expansion of the oil and gas industry comes with inevitable coexistence with communities. Several health concerns result from this proximity—for instance, contact with contaminated water or polluted air. One hazard, however, stands out: the potential release of toxic gases such as sulfur dioxide or hydrogen sulfide.

“Through the years, companies have been developing solutions for safer operations of oil and gas facilities that face toxic gas risks, often learning lessons the hard way. Organizations typically plan for any potential leaks and have measures in place to protect their site employees and contractors. With an increasing number of operations occurring in highly populated areas, there is now more focus on community protection measures,” said Elie Daher, executive vice president of United Safety.

What can companies do to ensure the safety of surrounding communities in the event of a toxic gas release?

The first point is ensuring operations are run as safely as possible, in order to avoid incidents. Safety personnel ensuring compliance with safety policies and adequate safety equipment should be on site. If toxic gas is present in drilling, production, or refining operations, companies should ensure all workers are oriented on site-specific hazards, emergency preparedness, and responsibilities and that people accessing critical zones have the proper training.

Nonetheless, even with precautionary measures in place, unplanned releases may still happen. In order to minimize external effects, companies need to work on community protection.
The first step is to determine the reach of a potential release. As toxic gases leak in the air, solar heating/radiative cooling determined by cloud coverage and latitude from the equator, wind speed and direction, surface roughness, terrain, and height from the ground are all factors that will affect where the plume will be headed and whether it will reach a populated area in a concentration that is harmful to the community. In addition, density of population in the area, access and egress routes, and source elements such as diameter, initial jet density, velocity, proximity, obstacles, and fallouts are important when estimating or predicting the dispersion of this toxic gas and its effect on a nearby community.

Map of emergency planning zone.

Map of emergency planning zone.

Several types of dispersion models exist, and many computer programs exist to create the models. Selection depends on input complexity and output requirement. The result of the dispersion study determines an emergency planning zone (EPZ), carefully delimited to ensure the safety of the public near the site.

Based on the specific characteristics of the EPZ, an EPZ monitoring plan and an emergency response plan (ERP) are crafted.

The execution of the EPZ monitoring plan requires incredible coordination to be effective. Checkpoints and road block locations need to be set up. It is a good measure to assign road block personnel to brief all people approaching with the correct information and status of the area and keep a log on transient people entering the EPZ. As part of the EPZ monitoring plan, mobile air-monitoring units are deployed to track ambient conditions and establish plume tracking in the event of a gas release. Stationary gas-monitoring equipment must be deployed at strategic places such as community perimeters or road blocks to be able to generate continuous condition reports. The placement of the air monitoring stations should be based on prevailing wind conditions and aligned with dispersion modeling results.

Community perimeter monitoring with Quazar.

Community perimeter monitoring with Quazar.

Communication technology such as wireless, general packet radio service, or worldwide interoperability for microwave access communication can be applied to gas monitoring and public protection. Innovations such as the Quazar from United Safety use both radio and Web technologies to get the right information at the right time to the right people. Data such as gas readings, wind speed, wind direction, global positioning satellite coordinates, unit identification (location), and distances from project/work site or other designated points are transmitted through wireless technology to the base, which, in turn, processes and averages data in order to facilitate well-timed decisions.

In the event of a release, the ERP will be executed. It should be quick, effective, and appropriate to protect the public, in addition to employees and contractors. It is crafted on the basis of different levels of emergency and provides the preparedness and response to the release. It should contain details on emergency definition and action, responsibilities of company and local authorities, evacuation and sheltering places, ignition procedures, resident information, maps, and more. A warning and public alarm system that is both visible and audible also needs to be in place. This ensures early notification so a timely community evacuation can be performed.

Another important factor on ensuring community protection is public relations. Media attention and intense public pressure make the ability to communicate within the response team as well as with stakeholders critical. A communications process/plan must be implemented and tested during drills.

The community must receive air monitoring data and activities schedules regularly, establishing confidence in the functionality of the safety program. EPZ personnel can also be used to communicate with residents. Another best-practice is distribution of a resident information package with a brief summary of the proposed activities, evacuation and ignition procedures, emergency telephone numbers, and a description of the hazards of the toxic gases present.

“Public protection still has some catching up to do when compared with onsite technology and safety measures,” Daher said. “To minimize impacts of toxic gas releases, companies should take into consideration the integration of gas monitoring and alarm equipment, communication, analysis of data, and dispersion modeling, culminating in a solid ERP plan. This is key to sustain long-term protection of the public living near oil and gas operations.”

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