Minimizing The Impact
Plume modeling enables immediate contingency planning to minimize the impact of an accidental chemical release.
Industrial chemicals can be stored in large tanks and containers on a manufacturing facility’s premises.
Protecting Employees And Local Residents
Accidental spills of toxic liquids or releases of gaseous chemicals due to a rupture in a tank, accidental spills from a transfer line, or releases from compressed gas tankers can have devastating effects on plant employees and surrounding residents. The list of hazardous chemicals that can cause serious problems for a textile facility if spilled or released is extensive; and includes hydrochloric acid, formaldehyde, benzidine, chemical solvents, bleaching agents, dyes, various acids and countless other chemical products. Whether a facility stores thousands of gallons of these chemicals in large tanks or merely a few gallons in totes and drums, disaster can result from a spill. When any toxic chemicals are released into the environment, concentrations of these chemicals in the air can range from an odor nuisance level to an immediately dangerous to life and health (IDLH) level. Each of these levels creates a different impact on the facility and its surroundings, and each requires a different response. The impact area for a specific spill or release event must be determined using various factors such as the chemical of concern; size of the release; topography and existing structures in the surrounding area; and a variety of atmospheric conditions such as wind speed and direction, humidity, and ambient temperature. Depending on the toxicity of the chemical, response actions ranging from personal protection to evacuation from the projected impact area may be required. Necessary actions for basic protection may include special respiratory protection, while more drastic actions may involve evacuation of the facility premises, or evacuation of residents around the facility if an impact area is determined to proliferate beyond the facility property.
The textile industry needs to take the danger of chemical spills and releases seriously. One state regulatory agency states that with so many process chemicals being stored, mixed and transported at most textile mills, the potential for spills is high. Even seemingly minor spills can have major environmental impacts. Processes such as scouring, bleaching and dyeing especially pose environmental problems. Many textile facilities are now using substitutes for hazardous chemicals, which help protect employees and the surrounding community in case of a spill, but serious problems may still result in the case of a spill or release, and they need to be addressed before an incident occurs.
Plume Dispersion Modeling
Clearly, being prepared for a crisis spill or release situation is critical, and the most important question of all then becomes: How can the textile industry prepare itself to handle such an incident? This dilemma will continue to be faced by countless members of management in plants across the nation. Contingency planning is the solution to this problem. Having a system that allows management to know immediately the proper course of action to take is the first step in emergency response. Plume dispersion modeling can aid in this contingency planning, allowing the decision-making process to be as easy, clear and comprehensive as possible.
The dispersion model uses complex calculations to determine the area affected by a toxic release and the chemical concentrations within the affected area. Through numerous iterations, a Gaussian plume model takes into account the nature of the chemical released as well as atmospheric factors to determine the dispersion of the release. The characteristics of the chemical released, such as its density, affect its transport insofar as determining how high above ground the plume will rise. This plume height affects the diffusion of the chemical at ground level, the location where the toxic concentration levels are most crucial. Atmospheric considerations such as air turbulence and wind velocity also will affect the dispersion of the chemical. Plume dispersion modeling takes into account all of these variables to give an accurate risk assessment for a toxic spill or release.
A good modeling program at a textile facility deals individually with the various toxic chemicals stored that potentially could spill and create a hazardous situation. Using predetermined atmospheric conditions, the location of the spill/release, and various spill/release sizes for each chemical, the program will compute the concentrations of the different hazardous chemicals in the air at ground level. Three different impact levels are considered - nuisance odor (half of the permissible exposure limit [PEL] value), PEL and IDLH. Each chemical's area of impact at these different levels is then determined. Once modeling of these scenarios is complete, the computed results can be applied practically to the development of contingency plans.
Determining Response Actions
Necessary response actions - such as respiratory protection, evacuation of certain areas within the facility premises, or evacuation of individuals residing in the surrounding community - can be determined from the results of a good plume model. A textile facility can fully prepare itself to implement appropriate action in the case of a hazardous spill or release. Conversion Technology Inc., Norcross, Ga., has developed a modeling program to aid facilities in handling this responsibility. Using a user-friendly graphical format, the program presents the sizes of potential spills and releases and their impact areas. The graphs are superimposed on maps depicting the facility and its surroundings, showing exactly what areas of the facility and community would be impacted by a spill (See Figures 1 and 2). Facility management then can easily determine the situations it must be ready to address.
When a chemical spill or release occurs, facility managers are confronted with the overwhelming task of determining an appropriate course of action at a moment's notice, while facing the concerns of employees, neighbors, community leaders and government officials. The first thing emergency responders (fire department and health department) will want to determine when an incident occurs is the immediate threat to people in the area. Having an adequate contingency modeling system in place provides that information immediately. It is irresponsible to take any chances when the consequences of an incident can include large fines from government agencies, a ruined company reputation, and illness and/or death of employees and local citizens - a public relations nightmare. When disaster occurs, when emergency strikes, it is essential to be prepared by having reliable information at hand. Fortunately, the development of contingency planning through the use of a specific plume modeling program has provided a solution to ease this burden on facility management. By implementing a working contingency plan, a textile company becomes ready to protect not only its employees, but also the surrounding community when an accidental spill or release occurs at its facility.