Wastewater Blending

In November 2003 the Environmental Protection Agency (EPA) proposed a policy regarding a type of wastewater treatment practice called blending. Some cities use blending to manage peak flows of water and waste into wastewater treatment plants during and after storms as a way to prevent conditions that otherwise result in raw sewage backups into homes and other buildings or overflows into nearby waters. Blending involves routing excess wastewater around the plant's biological treatment processes and recombining this excess flow with fully treated wastewater before discharging it to a stream or lake. As of February 2005, EPA has not yet issued a final version of the blending policy, which is intended to clarify when the practice can be allowed and still adhere to Clean Water Act regulations and requirements. Although blending has been standard engineering practice for several decades as a way to manage peak stormwater flows, controversy exists about the practice, both among stakeholder groups and also internally at EPA, where enforcement officials have challenged the practice and in some cases opposed allowing cities to use it. Others at EPA believe that, with certain restrictions, the practice is legal and environmentally protective. This report provides background on blending, why and how it is practiced, EPA's proposed policy, associated issues, and congressional interest in the topic. It will be updated as warranted. Criticism of blending focuses on three concerns: legality of the practice, impacts on public health and the environment, and other policy issues. A number of groups and interests have weighed in on all of these issues, especially in comments on the November 2003 proposed policy. Environmental advocates say that the practice of blending is inconsistent with existing rules that prohibit intentional bypass of a treatment facility. These groups have also raised substantial concern about public health and environmental impacts from discharges of wastes that contain pathogenic organisms. Many cities and municipal organizations support the EPA policy and practice of blending, saying that if cities are barred from blending, they are forced to make costly infrastructure investments, with limited benefit. While a number of states support the EPA policy, others oppose it for reasons including concern that the policy would undermine incentives for cities to remedy the infrastructure problems that result in sewage overflows. In Congress, these issues have drawn some attention. In January 2004, Members with differing views wrote to EPA to express concerns about the proposed EPA policy. Congress has several options at this point, ranging from allowing EPA to handle the issue administratively, to conducting oversight of issues raised by the proposed policy, or to legislating in order to direct EPA's actions, by expressly permitting, prohibiting, or modifying the policy. Legislation intended to bar EPA from issuing blending rules or guidance was introduced in the 108th Congress (H.R. 5421), but no action occurred on the bill.

Wastewater blending : hearing before the Subcommittee on Water Resources and Environment of the Committee on Transportation and Infrastructure, House of Representatives, One Hundred Ninth Congress, first session, April 13, 2005.

From explanations of laws and regulations to hands-on design and operation-the Handbook has it covered!

The effective integration of water and reclaimed wastewater still requires close examination of public health issues, infrastructure and facilities planning, wastewater treatment plant siting, treatment process reliability, economic and financial analyses, and water utility management. This book assembles, analyzes, and reviews the various aspects of wastewater reclamation, recycling, and reuse in most parts of the world. It considers the effective integration of water and reclaimed wastewater, public health issues, infrastructure and facilities planning, waste-water treatment plant siting, treatment process reliability, economic and financial analysis, and water utility management.

Step-by-step procedures for planning, design, construction and operation: * Health and environment * Process improvements * Stormwater and combined sewer control and treatment * Effluent disposal and reuse * Biosolids disposal and reuse * On-site treatment and disposal of small flows * Wastewater treatment plants should be designed so that the effluent standards and reuse objectives, and biosolids regulations can be met with reasonable ease and cost. The design should incorporate flexibility for dealing with seasonal changes, as well as long-term changes in wastewater quality and future regulations. Good planning and design, therefore, must be based on five major steps: characterization of the raw wastewater quality and effluent, pre-design studies to develop alternative processes and selection of final process train, detailed design of the selected alternative, contraction, and operation and maintenance of the completed facility. Engineers, scientists, and financial analysts must utilize principles from a wide range of disciplines: engineering, chemistry, microbiology, geology, architecture, and economics to carry out the responsibilities of designing a wastewater treatment plant. The objective of this book is to present the technical and nontechnical issues that are most commonly addressed in the planning and design reports for wastewater treatment facilities prepared by practicing engineers. Topics discussed include facility planning, process description, process selection logic, mass balance calculations, design calculations, and concepts for equipment sizing. Theory, design, operation and maintenance, trouble shooting, equipment selection and specifications are integrated for each treatment process. Thus delineation of such information for use by students and practicing engineers is the main purpose of this book.

This book will present the theory involved in wastewater treatment processes, define the important design parameters involved, and provide typical values of these parameters for ready reference; and also provide numerical applications and step-by-step calculation procedures in solved examples. These examples and solutions will help enhance the readers’ comprehension and deeper understanding of the basic concepts, and can be applied by plant designers to design various components of the treatment facilities. It will also examine the actual calculation steps in numerical examples, focusing on practical application of theory and principles into process and water treatment facility design.

In November 2003 the Environmental Protection Agency (EPA) proposed a policy regarding a type of wastewater treatment practice called blending. Some cities use blending to manage peak flows of water and waste into wastewater treatment plants during and after storms as a way to prevent conditions that otherwise result in raw sewage backups into homes and other buildings or overflows into nearby waters. Blending involves routing excess wastewater around the plant's biological treatment processes and recombining this excess flow with fully treated wastewater before discharging it to a stream or lake. As of February 2005, EPA has not yet issued a final version of the blending policy, which is intended to clarify when the practice can be allowed and still adhere to Clean Water Act regulations and requirements. Although blending has been standard engineering practice for several decades as a way to manage peak stormwater flows, controversy exists about the practice, both among stakeholder groups and also internally at EPA, where enforcement officials have challenged the practice and in some cases opposed allowing cities to use it. Others at EPA believe that, with certain restrictions, the practice is legal and environmentally protective. This report provides background on blending, why and how it is practiced, EPA's proposed policy, associated issues, and congressional interest in the topic. It will be updated as warranted. Criticism of blending focuses on three concerns: legality of the practice, impacts on public health and the environment, and other policy issues. A number of groups and interests have weighed in on all of these issues, especially in comments on the November 2003 proposed policy. Environmental advocates say that the practice of blending is inconsistent with existing rules that prohibit intentional bypass of a treatment facility. These groups have also raised substantial concern about public health and environmental impacts from discharges of wastes that contain pathogenic organisms. Many cities and municipal organizations support the EPA policy and practice of blending, saying that if cities are barred from blending, they are forced to make costly infrastructure investments, with limited benefit. While a number of states support the EPA policy, others oppose it for reasons including concern that the policy would undermine incentives for cities to remedy the infrastructure problems that result in sewage overflows. In Congress, these issues have drawn some attention. In January 2004, Members with differing views wrote to EPA to express concerns about the proposed EPA policy. Congress has several options at this point, ranging from allowing EPA to handle the issue administratively, to conducting oversight of issues raised by the proposed policy, or to legislating in order to direct EPA's actions, by expressly permitting, prohibiting, or modifying the policy. Legislation intended to bar EPA from issuing blending rules or guidance was introduced in the 108th Congress (H.R. 5421), but no action occurred on the bill.