Megastorms and terrorist threats compel planning

The powerful storm surge caused by Hurricane Sandy has highlighted the potential for large volumes of water becoming contaminated.  The EPA identified 45 Superfund sites within a half mile of coastal New York and New Jersey, and in its early assessment, the Agency confirmed that intruding stormwater reached at least two of these sites.

To protect public health and the environment, the resulting contaminated water should be collected or confined and either disposed of in its contaminated state or treated and sent to surface water bodies or groundwater.  Local governments, drinking water systems, and wastewater treatment facilities (WWTFs) face a complex assortment of technical and regulatory challenges in dealing with massive quantities of contaminated water.   The challenge becomes exponentially more difficult for small governments.

In a new guidance document, Containment and Disposal of Large Amounts of Contaminated Water: A Support Guide for Water Utilities, the EPA provides assistance.

Since the events of September 11, 2001, all levels of government have focused intensely on protecting drinking water and, to a lesser extent, wastewater systems from harm that can be caused by terrorist attacks.  One result has been a new culture of water-related security to detect and block such attacks from happening.  While stormwater intrusion into sources of drinking water and wastewater treatment plants has always been an important consideration for municipal governments, the vast contamination problems caused by Hurricane Katrina and the yet-to-be-quantified contamination following Hurricane Sandy have raised new concerns about the potential for super storms inundating coastal areas occupied by industrial facilities, tank farms, landfills, sewer systems, and hazardous waste sites.

There is much discussion as well as disagreement over whether these catastrophic weather events are a product of climate change.  The important consideration is that they are occurring with increased frequency, and those in charge of drinking water and wastewater systems must now be prepared and equipped to mitigate the impact.

The EPA guidance is intended to provide an overview of the issues associated with containment, treatment, and disposal of water contaminated with chemical, biological, or radiological (CBR) contaminants after a decision to contain the water has been made.  These issues include types of containment, treatment methods, disposal options and associated considerations, and information on some of the key relevant statutes and regulations that may be applicable for containment and disposal.

Containment

Contaminated water generally should be contained and treated either in situ or using temporary storage consistent with applicable regulatory requirements.

• In situ.  A hydraulic map of the water system may assist in identifying potential locations of contamination.  Water may be able to be contained:
• –Before the drinking water distribution system.  Contaminated water can be contained if it has not yet entered the drink­ing water distribution system (e.g., it is in storage tanks at the drinking water treatment facility).  Considerations include the feasibility of containing water and preventing it from entering the distribution system and the health and safety of drinking water system personnel (e.g., Will containment result in further exposure of workers to contaminants?).
• –Within the drinking water distribution system.  Contaminated water that has entered the distribution system may be contained within the system by turning off valves and pumps and advising customer(s) to keep faucets closed.  Considerations include the feasibility of containing water within the system (e.g., construction, age, and design life of infrastructure as well as the ability to shut off valves and the timeline for these activities); water within the drinking water distribution system posing a risk to those serviced by the closed-off portion of the system; notifying the public when contaminated water is contained within the distribution system; leaks, poorly sealed connections, corrosion, old breaks, etc., that may also allow release of vapors and water; and contaminated water exacerbating corrosion of connections, pumps, etc.
• –Within the wastewater or stormwater system.  Contaminated water can be contained in the wastewater system (e.g., in overflow tanks, sanitary sewer pipes) or stormwater system (e.g., in stormwater collection pipes).  Considerations include system capacity, intake flow rates, design life of infrastructure, and availability of shutoff valves; leaks, poorly sealed connections, corrosion, old breaks, etc., that may also allow release of vapors and water; contaminated water exacerbating corrosion of connections, pumps, etc.; containment raising the potential of further exposure of workers to contaminants; notifying the public when contaminated water is contained within the system and preventing sewage backups in homes; leaks within the system (e.g., collection and conveyance) that, depending on the severity, may require action (e.g., deploying hazmat teams) by the appropriate authority (e.g., fire department, health department).
• Temporary storage.  The in situ option may not be feasible for systems that do not have adequate infrastructure or in cases where contaminants may adhere to the walls of pipes or other system elements and recontaminate water later conveyed through the system.  In such cases, containment in temporary storage may be the better approach.  Types of temporary storage include tank trucks (capacity ranges from 5,000 to 9,000 gallons), on-site or off-site holding tanks, and empty water basins.

                 Key considerations include the location of temporary storage and transportation requirements; structure and integrity of temporary storage; security at temporary storage locations; duration of storage; regulations affecting construction of temporary storage areas; and whether either the locations of the structures or the structures themselves pose risks to the public, environment, or emergency responders.
                 Temporary storage is also a regulated activity.  Depending on the type of contaminant and the volume, a wide range of statues and regulations come into the picture.  For example, stored chemical waste is subject to underground storage tank and Resource Conservation and Recovery Act (RCRA) rules; biological contaminants are covered by state medical/infectious waste rules; radiological contaminants may be subject to Nuclear Regulatory Commission (NRC) licensing (unless the licensing requirement is waived); and RCRA applies to low-level mixed waste (LLMW)—a combination of low-level radioactive waste (LLRW) and hazardous waste. 

Treatment

The guidance lists many factors that must be considered when treating contaminated water.  For example:

• Water should be treated until it meets the clearance goals in accordance with any ap­plicable laws and regulations. Sampling and analysis should be used to verify if clearance goals have been met.
• Characteristics such as water alkalinity, hardness, and turbidity may influence the efficacy of treatment and the ability to accurately analyze water samples.
• Location of the water within a water distribution system, wastewater convey­ance system, or other location can limit treatment options.
• During the treatment process, contaminants may become concen­trated.  Precautions may include appropriate safety placards and labeling, use of personal protective equipment, and limiting periods of exposure.  Extra safety precautions should be taken with residuals that may have high levels of radioactivity.
• Chemicals such as chlorine, chlorine dioxide, and chloramines used to treat water contaminated with biological contaminants are typically regulated as pesticides under the Federal Insec­ticide, Fungicide, and Rodenticide Act (FIFRA), in which case they may be used only in accordance with their labeling.  A FIFRA exemption should be requested and obtained for off-label use of a regis­tered pesticide or use of an unregistered pesticide.

Disposal

When considering containment, treatment, and disposal of contaminated water, disposal will in most cases be the most regulated activity.  Water containing certain contaminants or exhibiting certain characteristics may be subject to statutes such as RCRA, the Clean Water Act, and FIFRA and their implementing regulations.   The EPA guidance offers five disposal options.

1. Direct discharge to surface water. Considerations include locating an accessible and appropriate body of water, applying for a new or modifying an existing National Pollutant Discharge Eliminations System (NPDES) permit, testing the water to confirm that contaminant levels are below the acceptable discharge levels listed in the NPDES permit, and obtaining a license or other approval from the NRC or the NRC-agreement state to discharge radiological water. 

2. Disposal to a WWTF.  If contaminated water is contained within the wastewater system, disposal may be appropriate through the WWTF of the system consistent with the NPDES permit requirements or any other applicable permit.  It should be determined if the water can be processed through the wastewater system without causing an untreated pass-through, interference, violation of applicable pretreatment requirements, or if the water should be transported to another WWTF.  Different types of WWTFs may have different requirements for accepting water.