Wastewater-treatment plants pose inherent risks to a community. Service disruptions at these facilities could threaten both the environment and public health while causing a breach in the public's confidence. Government officials have long recognized these dangers and the damage that could be caused by accident, human error, natural disaster or terrorist attack. In the wake of the Sept. 11 terrorist attacks, there has been an increased interest in these facilities and their vulnerabilities. First responders must plan for events at these facilities that could involve hazardous waste, bioterrorism, fire, evacuation and even confined-space rescue.

The wastewater facility in Atlantic City, N.J., seemed an excellent choice for a risk analysis. The Atlantic County Utilities Authority's Regional Wastewater Treatment Facility proved to be ahead of the curve in many ways, but the risk assessment shed some light on the weaknesses of the system in general.

The U.S. Government Accountability Office estimates that there are more than 16,000 publicly owned wastewater-treatment facilities in the United States. These facilities are located in every state and serve more than 200 million people, or approximately 70% of the population. Of those, a small number of large facilities serve the vast majority of customers. And for obvious reasons, these often are located near heavily populated urban areas. More than 800,000 miles of sewers feed these plants through 100,000 major pumping stations.

Here's how they work. Common sewage operations involve billions of gallons of wastewater, seepage, leachate and liquid sludge being pumped or trucked into the plants each day. Large solids are removed by a series of bar screens before the wastewater enters the primary clarifiers. The flow is slowed in the primary clarifiers to allow solids to settle to the bottom. Overflow is channeled to the aeration basins where the dissolved solids are digested by microorganisms. The wastewater then enters the secondary clarifiers. At this point, 85% to 95% of the pollutants have been removed. In the final stage, the treated effluent is disinfected before being released back into the environment. Throughout the process, solids that collect at the bottoms of the clarifiers and aeration basins are collected, thickened, dewatered and incinerated.

GAO identified the collection systems' network of sewers lines, treatment chemicals, key components of the wastewater-treatment plant, control systems and pumping stations as the five the most serious vulnerabilities to the wastewater system. Understanding these components and their weaknesses is the key to developing strategies to ensure the best possible outcome in an emergency situation.

Underground sewers collect waste from both sanitary and storm water lines. These pipes range in size from 4 inches to more than 20 feet in diameter. Sewers are connected to buildings through plumbing and commonly run beneath streets. Lack of security at manholes and inlets make them easily accessible to vandals and terrorists. This easy access allows terrorists to place destructive devices there, which could cause major damage to any structures above, possibly killing those in its path.

The sewers themselves do not have to be entered for a destructive agent to be introduced into the system. On June 23, 1977, petroleum naphtha was released into the sewer in Akron, Ohio. The resulting explosion some 3.5 miles away damaged 5,400 feet of sewer line and caused more than $10 million in damages. Attacks of this nature by highly toxic chemicals also could destroy the biological agents used in the aeration basins as part of the treatment process.

According to the U.S. Environmental Protection Agency, the useful life of a wastewater-treatment facility is approximately 20 years. Upgrades, renovations and expansions are often ongoing. The condition of a facility is observed easily and inspected regularly. This is not the case with the nation's sewage piping network. With a useful life of roughly 50 years, the vast majority is in poor condition and in need of replacement. Recently, a 60-year-old pipe in Atlantic County started leaking sewage into the bay. The county temporarily prohibited swimming, fishing and crabbing, and closed two area shellfish beds.

The transportation, storage and use of chlorine gas present an extreme danger to the surrounding communities. Chlorine gas, which is transported most often by 90-ton railroad tankers, is kept as a liquid under high pressure. It vaporizes into a gas cloud when released and hangs low to the ground because it is heavier than air. In high concentrations, pure chlorine gas is fatal; in lesser concentrations, it can burn the eyes, lungs and skin. In fact, Germany used it as a chemical weapon during World War I.

This chemical is not only extremely dangerous to the areas surrounding wastewater plants that still use it, but also to all the areas along its transportation route. The danger to residents of nearby wastewater facilities was recognized prior to 2001. According to a report for Environmental Defense by Carol Andress, an effort to switch to safer disinfectants was already under way, and has since been accelerated. In August 1994, the Blue Plains Sewage Treatment Facility in Maryland accidentally released a small plume of chlorine gas. Four men fishing on the Potomac River were overcome and hospitalized; two nearly died.

In 2003, it was estimated that 20 million people who were once at risk of chlorine gas exposure were safer because facilities in their areas switched to using sodium hypochlorite or ultraviolet light. Nineteen million people remain at risk from just 45 wastewater facilities in heavily populated areas, the Andress report says. Additional plants using chlorine gas may not be included in the above figures due to their remote location and low impact on public safety. As of 2007, only 13 wastewater facilities still received chlorine gas by railroad. The trend continues to move toward the safer alternatives or transporting chlorine in safer 1-ton canisters at the very least.

Due largely to risk-management plans and fees required by the New Jersey Toxic Catastrophe Prevention Act, almost all 290 wastewater facilities in New Jersey that reported using chlorine gas when the program began in 1988 have now eliminated or significantly reduced their use of chlorine gas, Andress reports. The ACUA eliminated the use of chlorine gas and converted to sodium hypochlorite in the early 1990s. With three large casinos and a heavily populated neighborhood in close proximity to its facility, this conversion eliminated a large life hazard and potential problem for the Atlantic City Fire Department.

The key components of the wastewater-treatment plant each play an important role in the treatment process. The bar screens, primary and secondary clarifiers, aeration basins, and disinfection and effluent pumping station all must be in proper working order. Damage to any one of these components could result in inadequately treated wastewater. Wastewater-treatment facilities plan for natural disasters, but protecting the plant from attack has not been a high priority. Many facilities now are considering ways to improve their security. Experts have identified the headworks, where the wastewater first enters through the collection system, as particularly vulnerable to attack. Restricting or blocking the flow of the wastewater into the facility could cause backups throughout the collection system, creating a public health hazard.

In New Jersey, the ACUA's wastewater facility is completely surrounded by water with only one bridge and access road connecting it to a main highway, Route 30. ACUA's management is concerned that access to and within the treatment plant could be blocked by hurricane or storm-tide conditions. With increased attention by the federal government toward improving security at wastewater-treatment facilities, ACUA has installed an electronically controlled gate and intercom system at the entrance to the property. Nonetheless, the property is still vulnerable to acts of nature and terrorism. The impediment of movement to and from ACUA's property would cause major problems with both response and evacuation.

The sewage system uses pumping stations when gravity is insufficient to move waste. One expert explained in the Andress report, “One pumping station has the capacity to pump 25 million gallons of wastewater per day.” Another expert added that, “Destroying or disabling a pumping station could cause the collection system to overflow raw sewage into the streets, and into surface waters, and back up sewage into homes and businesses…. The remoteness and geographic distribution of pumping stations, and their lack of continuous surveillance, make them particularly vulnerable.”

With approximately 60 miles of sewer pipes and more than 20 pumping stations, ACUA vulnerabilities are spread throughout 14 municipalities. In Atlantic City alone, the risk to 12 casinos and hundreds of thousands of daily visitors makes this a serious concern. The problem is increased because Atlantic City and nine of the surrounding communities border the bay or ocean. An overflow of raw sewage could threaten the health of humans, wildlife and the environment of Southern New Jersey.

According to GAO, wastewater facilities increasingly are using control systems, such as the Supervisory Control and Data Acquisition network. These systems monitor and control operations from a central location. Misuse of the SCADA could cause too-high or too-low levels of chemicals to be introduced into the treatment process, reduction in biological treatment levels or the collection system to be shut down remotely. Non-encrypted systems' access via the Internet are particularly vulnerable to cyber attacks. In 2000, a breach in cyber security caused thousands of gallons of raw sewage to be released in Australia.

Many remote systems can still be worked manually but the personnel must be available when the time comes. In the case of the ACUA, the buildings on the property have a limited fire-protection infrastructure. The main control room in the operations building, with all the electrical equipment that controls the wastewater operations, is not even protected by a halon system. There are smoke detectors, but when activated, the alarm must be called in manually to Atlantic City's 911 dispatcher.

Wastewater-treatment facilities present additional concerns to first responders. Regardless of the disinfecting agent used, there still will be hazardous materials on site. Laboratories also are likely to be on site, which should always raise a red flag. SARA Title III requires all hazardous materials to be inventoried on three separate forms. The forms, OCC-51A (small quantities), OCC-51B (small quantities in a laboratory) and OCC-51C (large quantities), must be filed with the location's fire and police departments. These forms also list the locations of each hazardous material and how many people work in that building. Additionally, Materials Safety Data Sheets for each chemical should be kept on site for use in the event of an emergency.

As with any industrial facility, power is a concern to first responders. Wastewater-treatment facilities use electricity to collect and treat wastewater and discharge the clean effluent. There is a trend toward using alternative sources to generate this electricity. Methane gas produced during the anaerobic digester process can be used to generate part of the plant's electricity. In ACUA's case, five wind turbines are used to produce 60% of the plant's electrical needs. Methane gas adds to the list of hazardous materials and wind turbines make for potential confined-space and high-angle rescues. Both scenarios present additional dangers that must be planned for during any risk analysis.

All the wastewater operations are redundant, so the entire facility can continue to operate at a reduced capacity if part of the system breaks down or is in need of maintenance. ACUA routinely shuts down its incinerator for cleaning and maintenance. A backup incinerator can handle the operations for a short period of time. Of its five primary clarifiers, six aerations basins and six secondary clarifiers, any number can be shut down temporarily as long as one of each is running. Problems would arise if an entire component were disabled and sewage were restricted or blocked the flow of wastewater through the facility.

The clarifiers, aeration basins, incinerators, pumping stations and sewage pipes are all permit-required confined-spaces as defined by Occupational Safety and Health Administration. These areas create hazards to both employees and rescue workers. Wastewater-treatment facilities should have policies in place as guidelines for their employees to operate under when working in these areas.

First responders are not responsible for the daily operations of a wastewater-treatment facility and have little or no control over how the utility is run. They are, however, tasked with responding to emergency incidents that arise in the course of their operations. Performing a risk analysis helps understand what types of emergencies they are likely to encounter and where those are likely to be.

An incident at a wastewater-treatment facility is likely to involve multiple agencies. In addition to the fire department, personnel and resources from law enforcement agencies, environmental authorities and public health care facilities may be called on to work together. The likelihood of a successful outcome will be greater if there is communication and coordination between these entities beforehand. Information gathered from a risk analysis should be shared among those likely to be involved. Ultimately this information should lead to training drills and tabletop exercises.

A thorough risk analysis of the local wastewater-treatment plant will highlight the hazards to the community and possibly better prepare the fire department's response.

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Joseph D. Rush III is a battalion chief and 21-year veteran of the Atlantic City (N.J.) Fire Department. He has a bachelor's degree from LaSalle University and is working on his master's degree at Saint Joseph's University. In August 2008 he was accepted into the National Fire Academy's Executive Fire Officers Program.