Peace of Mind

Oct. 9, 2003
Instrumentation plays key role in immediate assessment of an unexpected event, helping reduce impact to water treatment plants

About the author: Frank Kaiser is the instrumentation product manager for Severn Trent Services. He can be reached at [email protected] or 215/997-4025

Never before has the ability to rapidly monitor the quality of source waters for contamination been nearly as important as it is today.

Strict criteria for emergency response plans have been deployed under the Bioterrorism Preparedness and Response Act, where community water systems serving populations greater than 3,300 people must conduct vulnerability assessment, certify completion and provide written copy to the EPA.

Under the Bioterrorism Preparedness and Response Act, all emergency response plans, at a minimum, should include plans, procedures, and identification of equipment that can be implemented or used in the event of an intentional attack on a water treatment system.

In addition, actions, procedures and identification of equipment that can lessen the impact of such an attack must also be included in the vulnerability assessment.

It's also important to note, that while regulation is driving community water systems to perform vulnerability assessments, there is a simultaneous effort lead by the National Homeland Security Research Program, headquartered in the National Risk Management Laboratory in Cincinnati to provide appropriate, effective and rapid risk assessment guidelines and technologies to help decision-makers prepare for, detect, contain and decontaminate chemical and biological attacks directed against buildings and water treatment systems.

The major programs--Safe Building, Water Security and Rapid Risk Assessment--are the focus of research and development efforts at the National Risk Management Laboratory.

Within the Water Security Research Program, detection and characterization, response and mitigation, including validation of field portable monitors, and prevention and protection, are key research areas.

Rapid evaluation

Immediate assessment of an unexpected event is critical in reducing the impact to the treatment plants down stream. The ability to quickly evaluate the quality of water can save precious time and valuable resources. Possible contamination scenarios involve trespassing and vandalism at reservoirs and finished water storage locations.

"Years ago, simple graffiti on a water tank was labeled mischievous teens," said Barbara J. Luedecke, sales representative for Mcaulay Controls Co., a manufacturers representative organization. "Utilities can no longer take that risk."

When evidence of trespassing and vandalism are discovered, the ability to rapidly evaluate the water for possible contamination is essential.

"By running a simple test on site, an operator can know if there is a contamination issue," said Luedecke.

Initial testing need not quantify the exact contaminates used to pollute the water, but rather identify the overall quality of the water. If the water quality has been compromised, then more elaborate testing can be performed.

"It can take too long to receive analysis results back on water samples," said Luedecke. "Utilities would have to drain and clean tanks as well as have to notify the public. This process is expensive and can take weeks."

Instrumentation application

One fast-testing method for evaluating water pollution is Severn Trent Services’ Eclox Rapid Response Water Test Kit, which uses chemiluminescence, which is used to measure the amount of light generated when a water sample is combined with reagents. This enhanced chemiluminescence reaction produces light in direct proportion to the quality of the sample and is used to determine the relative toxicity of the water.

The chemiluminescence reaction utilizes the plant enzyme horseradish peroxidase to catalyze the oxidation of luminol, producing a flash of light. An enhanced is added to the sample to stabilize and prolong the emission of light produced by the reaction. The presence of free radical scavengers interferes with the reaction and toxicants in a sample interact with the enzyme to reduce light emissions.

The chemiluminescence test is broadband and qualitative, and is used to quickly ascertain whether the sample measured has been subjected to chemical or biological contamination.

"By including a kit like this in the plan, the utility can make a fast decision on how to handle an intrusion to the utility," said Luedecke. "Utilities are using this kit to save time and money."

Prior to testing the water sample, a baseline reading is established using de-ionized water and relative instrumentation included in the kit.

The de-ionized water is exposed to the reagents and the light generated is stored as a reference level. The test is then repeated with the water sample.

Depending on the level of toxins in the sample, light levels are reduced relative to the reference sample. The ratio of the light levels in the sample water and the de-ionized water provides an indication of the toxicity level of the sample.

Finished water typically produced 5-15% less light than the de-ionizer reference compared to river water samples, which can generate 35-75% less light. A reduction of 80% or more can be expected in treated sewage effluent.

Testing information

The following is an example of the detection limits that are reportable using the chemiluminescence process: 0.1 mg/L phenol, 1 mg/L copper, 1mg/L mercury, 0.01 mg/L cyanide, 0.1 mg/L arsenic, 0.1-5 mg/L carbamate pesticides, and 1-5 mg/L organophosphate pesticides.

Test information is immediately viewable on the luminometer display, with completed test results available in four minutes. The luminometer rapidly indicates the quality of the tested sample, and is used to indicate whether more extensive, time-consuming, and costly tests are required to identify the nature of the contaminants. If the luminometer results indicate that the sample is high in quality, typically, no further testing s required.

In an environment of continued uncertainty, communities must remain diligent in their safety procedures and emergency response plans. Using the newest available technology, routinely testing water for contamination can be fast, easy and inexpensive.

"What water operators must understand is that when investigating a terrorist or vandal contamination situation, there is no single test for providing full scientific certainty in making the tough decision 'is it safe to drink the water now?'" said Homer Emery, member of the Bexar County, Texas, Local Emergency Planning Committee and registered sanitarian, San Antonio Water System. "This decision must be made in coordination with local public health ad regulatory officials. A water contamination toolbox that the EPA is developing should be a big help in this decision-making process. The Eclox water quality assessment system, and similar testing kits, are simply additional tools for helping to make these types of decisions."

About the Author

Frank Kaiser

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