All Stirred Up

EPA addresses the controversial practice of utility discharge of partially treated wastewater during peak wet-weather flows

Many wastewater treatment plants that release partially treated wastewater during heavy rains are getting into hot water with nearby residents and various stakeholder groups.

This issue is not a new one, but the U.S. Environmental Protection Agency (EPA) currently is trying to assist operators at wastewater treatment plants through the development of a new draft policy that includes suggested strategies for managing wastewater during peak wet weather flows. However, even after EPA formally adopts this new policy, it will not be an enforceable regulation, and, consequently, will not be considered a legal mandate supported by the threat of a sanction or fine.

Throughout the United States, numerous municipalities have experienced high influent flows during significant wet weather events, such as large snow melts or heavy rainfall, and exceeded the treatment capacity of their secondary treatment units. Frequently in such situations, some of the wastewater is rerouted after primary treatment (when solids are removed) around the secondary treatment system (where pathogens are killed and pollutants removed) and then recombined (commonly known as “blended”) with fully treated wastewater. This partially treated wastewater then is discharged into nearby streams and lakes.

Citizens and stakeholder groups are concerned that peak wet weather flow diversions could have adverse environmental or public health effects because of the higher pollutant load of the diverted flow. Partially treated wastewater contains a variety of dangerous pathogens, including bacteria (such as
E. coli), viruses (such as hepatitis A), protozoa (such as Cryptosporidium and Giardia), and helminth worms. According to the Centers for Disease Control, there are estimated to be 7.1 million mild-to-moderate cases and 560,000 moderate-to-severe cases of infectious waterborne diseases in the United States annually. A large number of these cases are caused by exposure to untreated sewage during recreational activities such as swimming and boating in lakes, rivers, and oceans.

The Evolution of EPA’s Proposed Policy
In November 2003, EPA proposed a policy that deals with National Pollutant Discharge Elimination System (NPDES) permit requirements for municipal wastewater treatment plants serving sanitary sewers during wet weather conditions. The policy was intended to provide clarity about managing peak wastewater flows during significant wet weather events. Numerous public health and environmental organizations criticized the agency’s original policy. Opponents stated that it would have allowed wastewater treatment plants to discharge inadequately treated sewage into waterways virtually any time it rains. EPA received more than 98,000 public comments. In May 2005, the agency stopped work on the proposal and began reviewing different approaches and obtaining new, relevant information.

In December 2005, EPA issued a revised version of its proposed “peak weather flows” policy. It was based on a joint guidance developed after five months of negotiation between the National Association of Clean Water Agencies, which represents wastewater treatment plants, and the Natural Resources Defense Council, an environmental organization.

The agency’s draft policy includes some of the following key provisions:

*It requires utilities to submit to regulators a detailed list of reasons for blending treated and semi-treated wastewater during heavy rains as part of their permit-renewal process. The policy also requires regulators to keep the blending documents and the permit applications open to public review.

*It spells out limited circumstances under which the wastewater diversions around secondary treatment process are allowed. EPA specifies it only allows diversions in instances when a wastewater treatment plant has “no feasible alternatives” to diversion, the plant provides at least primary treatment to the diverted wastewater, and the resulting discharges meet applicable effluent limits based on secondary treatment. “Inadequate capacity” would no longer be an acceptable reason for blending.

*In the limited circumstances when the agency would allow wastewater treatment plants to blend fully treated and partially treated wastewater during heavy rains, it would require plant officials to notify the public within 24 hours of the blending event.

Not surprisingly, the proposed policy introduced in December 2005 has received criticism. For example, Bob Freudenthal, president of the American Public Works Association, found fault with the new draft policy in his recent President’s Message, which is posted on the organization’s Web site,
“EPA’s proposed guidance on the wastewater treatment practice of blending is likely to result in costly plant upgrades to comply with the new requirements that further strain the resources of water systems to serve their communities, protect public health, and protect the environment,” Freudenthal said.

Looking Ahead
The revised draft policy, which was published in the Federal Register 70 FR 76,013 (December 22, 2005), is intended to interpret the EPA regulation (40 Code of Federal Regulations 122.41(m). This regulation is commonly known as the “bypass regulation” and deals with NPDES permitting requirements.

In an interview with Water & Wastewater Products on January 12, Kevin Weiss, an EPA representative from the Office of Wastewater Management in Washington, D.C., said the proposed policy is being reviewed by the Office of Management and Budget. OMB is the White House office that is responsible for devising and submitting the president’s annual budget to Congress. One of OMB’s many duties involves reviewing all regulations and policies proposed by federal agencies, including EPA.

“We’re hoping OMB will finish its review of the policy by the end of March,” Weiss said. “If OMB doesn’t finalize it by the end of March, it possibly signals that OMB could take significantly longer.”

Once approved, the EPA policy will be published in the Federal Register. For more information about the draft policy, contact Weiss at 202-564-0742.

Operators at wastewater treatment plants need to stop relying on peak wet weather flow diversions around secondary treatment as their primary wet weather management approach. Hopefully, EPA’s most recently proposed policy will help wastewater treatment plant personnel come up with new strategies, such as increased storage and treatment capacity, which minimize the discharge of blended wastewater during heavy rains.

Industry Guide Helps to Evaluate Alternatives
In 2006, the Water Environment Federation (WEF) published a guide that offers management tips to wastewater plant operators on dealing with sewer overflows during heavy rains. WEF worked with EPA to develop The Guide to Managing Peak Wet Weather Flows in Municipal Wastewater Collection and Treatment Systems. The purpose of the guide is to provide a framework for owners, planners, designers, and operators of wastewater treatment plants to set objectives and evaluate alternatives for managing wastewater during heavy rains.

The guide also offers management tips for utilities to implement EPA’s proposed peak weather discharge policy that was issued in December 2005. The guidance describes a process that utilities can follow in identifying, evaluating, and determining whether feasible alternatives exist for peak weather flows.

This article originally appeared in the 03/01/2007 issue of Environmental Protection.

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