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Wastewater system owners face a variety of permitting challenges, particularly those dealing with wet weather issues such as sanitary sewer overflows(SSO). Ever since the Environment Protection Agency (EPA) formed the SSO Federal Advisory Committee in 1994, attempts have been made by
system owners to get the regulatory agencies to establish an SSO affirmative defense that realistically addressed alternatives for handling wet weather discharges prior to the treatment plant headworks. For instance, attempts to permit sanitary sewer discharges prior to the headworks have
been almost futile. The regulatory agencies have taken a rigid interpretation of the Clean Water Act in regards to collection system performance exceptions as compared to the treatment system. Conveyance systems have presented an awkward situation for the regulators given the fact that conveyance
systems are not intended to discharge but yet they are regulated under the same technology- or water quality standard as the treatment plant (which is designed to discharge). This paper presents a perspective on current regulatory limitations for sanitary sewer systems. It also presents
new permitting language that describes collection system performance which could help utility owners clarify compliance interpretations and open a dialogue with regulators. A common, but important, permitting negotiations point is how to better define key permit language expectations such
as how feasible alternatives are linked to system performance. System owners know that overflows from the collection system may occur even if the system is well designed and maintained. Those overflows from well designed and maintained systems are often associated with events outside the
planning, design and operational performance parameters of the system and well accepted engineering practice and standards. Collection system capacity and management, operations and maintenance (CMOM) approaches have not been refined and developed and approved as policy or guidance and are
not coordinated or linked with the technology- and water quality standards of the CWA. Generally accepted engineering and economic practices identify the best technology, along with specific design options and management practices. The risk analysis provides information on the consequences
of various alternatives, allowing a POTW to determine if there are “feasible alternatives,” that is, if additional investment and /or improved O&M will reduce sewerage-related risks to public health and the environment. This paper describes how both operators and regulators
can use similar permitting terms to evaluate whether system failures were avoidable and if further facilities and controls are required to manage wet weather flows. The paper also discusses how the management of the conveyance system must consider the difference between system deficiencies
that they can correct and system failures due to extreme weather or other conditions that may result in overflows that cannot be prevented by any reasonable plan or design. Both preventable deficiencies and failures from extreme conditions interfere with how a system is intended to function.
However, they are fundamentally different. The paper presents the basis for these differences and how this sets the stage for new permitting language. System deficiencies must be corrected. System failures should be viewed as performance exceptions and may or may not be corrected based
on their mode of failure and feasibility of corrective actions. Both system deficiencies and system failures pose potential risks, but they pose different planning and management challenges to determine acceptable levels of risk since treatment and conveyance systems cannot be managed or operated
risk-free any more than any other built system. Examples are presented in the paper of how system failures represent the practical limitations of wastewater treatment and collection systems to operate in extreme wet weather or other conditions that exceed generally accepted engineering
design and construction practices.
Proceedings of the Water Environment Federation is an archive of papers published in the proceedings of the annual Water Environment Federation® Technical Exhibition and Conference (WEFTEC® ) and specialty conferences held since the year 2000. These proceedings are not peer reviewed. WEF Members: Sign in (right panel) with your IngentaConnect user name and password to receive complimentary access.