ARCHIVE SITE - Last updated Jan. 19, 2017. Please visit www.NACWA.org for the latest NACWA information.
NACWA's Wet Weather Survey (Survey) provides critical information that will help to further understanding among state and federal regulators of the factors that publicly owned treatment works (POTWs) consider when sizing their sewer collection systems and treatment plants for peak wet weather flows. The Survey constitutes one step in an ongoing effort to highlight and examine the complex issues, including capacity-related issues, which comprise the broader picture of the current state of core wastewater infrastructure in the United States.
The United States Environmental Protection Agency (EPA), wastewater utilities, and other stakeholders continue to explore the development of appropriate regulatory programs and practices to reduce sanitary sewer overflows (SSOs), and to improve water quality. As this dialogue continues, NACWA believes it is essential to account for and understand how existing state and federal statutory and regulatory programs have shaped, and continue to affect, municipal planning, engineering decisions, and peak wet weather flow designs.
These existing design practices and planning considerations shed light not only on what is currently driving these sizing decisions, but also provide insight into how future policies and regulations governing wet weather flows should be crafted in order to preserve the tremendous achievements in water quality realized over the last thirty years.
The Wet Weather Survey Report (Report) has five main sections. Section 1 is an Executive Summary of the Report and the Survey’s findings. Section 2 provides an overview of the existing statutory and regulatory provisions and policies governing peak flows. Section 3 includes information on how NACWA designed and distributed the Survey and compiled the responses. Section 4 provides critical details on geographic distribution, government structure, and other Survey respondent profile information. Section 5 presents a summary of selected Survey question responses, grouped as follows:
Survey responses highlighted several key characteristics of POTW design and planning processes:
Municipalities are using a wide array of tools and approaches to design systems and plants and to manage peak wet weather flows. These approaches are working and municipalities must continue to have sufficient flexibility and a suite of options available to them for dealing with wet weather flows.
A one-size-fits-all approach will not work for highly variable wet weather flows. Any type of national program or standard must be general in nature and performance-based. Prescriptive requirements that dictate what design practices and planning considerations to use will only hamper current efforts by the wastewater community to improve peak wet weather flow management capabilities.
Based on the Survey responses, NACWA recommends that: