Lewis A. Rossman

DBP formation kinetics in a simulated distribution system.

Little is known about how the growth of halogenated disinfection by-products (DBPs) in drinking water is affected by time spent in a distribution system. Experiments were performed to compare the rate of trihalomethane and haloacetic acid production in a simulated pipe environment to that observed for the same water held in glass bottles. Results showed that although the rate of chlorine consumption in the pipe was much greater than in the bottle, there was no decrease in the amount of haloacetic acids produced and that trihalomethane levels actually increased by an average of 15%. Separate tests confirmed that this increase was due to a reservoir of organic precursor material associated with deposits on the pipe wall. This work suggests that the rate of DBP production in a distribution system will not necessarily be reduced by increased chlorine consumption due to non-DBP producing reactions with deposits on the pipe wall.

Modeling Low Impact Development Alternatives with SWMM

The U.S. Environmental Protection Agency’s Office of Water is actively promoting the use of Low Impact Development (LID) practices to help protect and restore …

SWMM 5 - the Next Generation of EPA's Storm Water Management Model

The U.S. Environmental Protection Agency’s Water Supply and Water Resources Division is partnering with the consulting firm of CDM to redevelop and modernize t…

AN OVERVIEW OF EPANET VERSION 3.0

EPANET is a widely used public domain software package for modeling the hydraulic and water quality behavior of water distribution systems over an extended period of time. The last major update to the code was version 2.0 released in 2000 (Rossman, 2000). Since that time there have been many useful advancements made in water distribution system modeling, many of which have been presented at past WDSA symposia. Several of these are being incorporated into an updated version of EPANET. Hydraulic modeling improvements include more efficient sparse matrix solution routines, the modeling of pressure deficient/dependent demands, more versatile options for controlling pump and valve settings, and improved stability for extended period analysis. Water quality enhancements include non-ideal mixing at pipe junctions, longitudinal dispersion within pipes, and more efficient implementation of the constituent transport procedure within pipes. In addition, several options for re-writing EPANET’s graphical user interface in a more user accessible language and platform-independent manner are being explored.

THE OPEN SOURCING OF EPANET

A proposal was made at the 2009 EWRI Congress in Kansas City, MO to establish an Open Source Project (OSP) for the widely used EPANET pipe network analysis program. This would be an ongoing collaborative effort among a group of geographically dispersed advisors and developers, working on a voluntary basis within an auto-governing organizational structure, which would allow members of the water distribution system modeling community to participate in the program’s development and improvement. After reviewing some key aspects of the OSP development process we discuss what issues these present to establishing an open source project for EPANET. These include justifying the need and benefit of such a project, establishing its membership and organizational structure, identifying the scope of development the project should pursue, and maintaining high quality control standards. Suggestions are made on what options are available to address each of these issues.

Water Resources Modeling Tools - Open Source Code versus Proprietary Software

The water resources engineering community has available an array of computer models that can be applied to support analysis, planning and design of water resou…