Unknown Exposures Are Potential Liabilities for Wastewater Treatment Plants

While wastewater treatment plants have the potential to contaminate the surrounding environment, their exposures can be addressed to reduce potential liabilities

Any facility that treats, stores or disposes of wastes faces environmental exposures. While these seem apparent at landfills or hazardous waste treatment facilities, environmental exposures are less obvious at facilities such as wastewater treatment plants. Nevertheless, wastewater treatment plants do face environmental exposures from their operations, with potential resulting liabilities.

As an example, consider the case of a wastewater treatment plant that utilized sulfuric acid in its process. The acid was stored on-site in a 20,000-gallon aboveground storage tank. The storage tank was contained by two foot-high, chemically-sealed concrete walls. Overnight, an area high on the wall of the storage tank ruptured, releasing the acid. The leak squirted beyond the secondary containment, releasing approximately 3,000 gallons of the tank contents onto the soil and into an adjacent stream. The government-mandated costs for cleanup of on-site soil, the stream and the stream bank exceeded $1 million.

Fortunately, environmental exposures can be mitigated through effective loss control techniques and risk transfers. The following is an exploration of the exposures facing wastewater treatment plants and how these exposures can be addressed to reduce potential liabilities.

Sources of Exposure

When the public thinks of wastewater treatment plants, unpleasant odors typically spring to mind. However, wastewater treatment plants have the potential to contaminate the surrounding environment from several main sources. Contamination can result from

  • discharges of contaminated effluent due to inadequate treatment
  • cracks in wastewater treatment tanks
  • leaks or releases from storage tanks
  • leaching of contaminants from sludge in on-site storage areas.


Effluent Exposures

The most obvious exposure at a wastewater treatment plant is the discharge of contaminated effluent. Effluent is typically discharged to surface water or groundwater, or else is sprayed on the land. The effluent generated at the end of the treatment process is supposed to be "clean." However, if the plant encounters any problems in the treatment process, the effluent many contain contaminants that then enter the receiving surface water, groundwater or soils. Problems that can upset the treatment process include

  • a treatment process breakdown
  • untreatable contaminants
  • excess volume from combined sewer overflows, resulting in treatment bypass.

Subsequently, the contaminated effluent can cause surface water, groundwater, and/or soil contamination. If contaminated effluent enters a surface water body, the following effects could occur:

  • fish kills
  • harm to human health (if the surface water body is used for recreational purposes such as swimming, boating and fishing)
  • contamination of a drinking water supply source.

Contaminated effluent also poses harm to groundwater that may be a drinking water source for both private and public wells.

Several loss control techniques can be used to help prevent losses from contaminated effluent. First, the plant should closely track its Discharge Monitoring Reports and use a reputable laboratory to test all samples. Such tracking will aid in early detection of effluent problems. Second, the facility should have a Preventive Maintenance Program in place to adequately maintain and replace equipment to prevent problems from occurring. Another way to minimize this exposure is to have a good audit program in place for all of the plant's industrial users. A good program will help to ensure that the facility is not receiving untreatable wastewater.

Tank Exposures

Most wastewater treatment plants utilize concrete tanks (that are often partially in the ground) to process the wastewater. Over time, these tanks can develop cracks. If these cracks are not repaired immediately, tank contents can emanate from the process tank and contaminate underlying soils and groundwater. This could result in on-site contamination and lead eventually to third-party property damage from contaminants migrating off-site. Once again, there is also the potential for contaminating groundwater that may be a drinking water supply source. Additionally, wastewater treatment plants generally use both underground and aboveground storage tanks to store process materials and wastes on-site. These tanks present several environmental exposures. Underground storage tanks may leak over time, and the contents have the potential to contaminate the underlying soils and groundwater. Aboveground tanks have the potential to present problems such as

  • leaks from tank bottoms
  • ruptures causing a catastrophic release of tank contents
  • spills during the loading or unloading process.

Tank exposures can be mitigated through the implementation of tank testing and maintenance programs. These programs schedule and track integrity testing of storage tanks, repairs and maintenance. Effective Spill Plans detail what action to take in the event a spill or release occurs. Timely and adequate response can help minimize the amount of a loss.

Storage Exposures

One of the process materials typically stored on-site is chlorine. A deadly gas, chlorine can kill people in the vicinity of a release. Therefore, on-site chlorine storage represents a major exposure. Chlorine detection systems with alarms can be used to provide an early warning of any problems with chlorine storage or handling. Plants should also have evacuation plans for the facility as well as the surrounding community in the event of a release.

Another practice of many wastewater treatment plants is on-site storage of sludge that is a by-product of the treatment process. Historically, "storage" simply meant placing the sludge on the ground or on wooden pallets. This old storage method may have resulted in contamination of underlying soils and groundwater. However, today, most plants store sludge in covered concrete areas, thus minimizing the impact of the sludge on the surrounding environment.

Odor Exposure

Indeed, there is also the potential for a wastewater treatment plant to have a negative effect on the surrounding environment simply by producing foul odors. While these odors are not harmful, they are unpleasant and could result in nuisance claims against the facility.

Reducing the Risks

The most effective way to reduce the environmental exposures facing wastewater treatment plants is through the integration of the preceding loss control techniques into a comprehensive loss control program. However, losses will still occur. When they do, pollution insurance programs are available in the marketplace that are both comprehensive and affordable.

Pollution liability insurance is currently available that provides coverage for both third party bodily injury and property damage resulting from pollution conditions emanating from a wastewater treatment plant, as well as on-site cleanup of the facility in the event contamination is discovered on site. Defense costs are also included. Therefore, this type of insurance policy would provide coverage if the wastewater treatment plant discharged contaminated effluent into a surface water body and subsequently impacted a drinking water supply source. Additionally, if the treatment tanks at a facility cracked and contaminated the underlying soils and groundwater, then this type of policy would provide for the cleanup of the impacted soils and groundwater. If the facility in the example at the beginning of this article had pollution coverage in place, its policy would have covered both the on-site and off-site cleanup.


Wastewater treatment plants do face environmental exposures. By being aware of these exposures, potential liabilities can be minimized through the implementation of effective loss control techniques. For those losses that do occur, pollution liability insurance is available to address both on-site cleanup of the site and third party bodily injury and property damage resulting from the operation of the plant.


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About the author

Victoria L. Ostertag, ARM, is a senior underwriter, with extensive environmental consulting and pollution insurance underwriting experience, at ECS, Underwriting, Inc., a national provider of insurance programs for companies facing environmental exposures. Victoria holds a Masters of Science degree in Environmental Health Administration.