Guidance Manua pdf

 

vi 

Hypolimnion  – the lower layer of a stratified lake.  During summer stratification, the 

hypolimnion has lower water temperatures than the epilimnion. 

 

Metalimnion  – the middle layer in a  lake, between the hypolimnion and epilimnion, 

where the temperature changes with depth.    

 

MIB  –  2-methylisoborneol, a volatile organic compound produced by blue-green algae 

and certain other microbes.  MIB is not known to be harmful to humans, but imparts an 

unpleasant moldy/musty taste to the water at concentrations > 5-10 ng/L. 

 

ng/L – nanogram per liter or one part in a trillion. 

 

Oscillatoria  – a filamentous genus of blue-green algae or cyanobacteria.  There are 

many species of  Oscillatoria, some are  phytoplanktonic (suspended) and others 

periphytic (attached).  Some species produce MIB and/or geosmin. 

 

Prechlorination  – chlorination that occurs before water reaches the coagulation-

flocculation basin. 

 

Presedimentation  – sedimentation that occurs in a  basin in front of the coagulation-

flocculation basin. 

 

Thermocline  – the depth at which the maximum temperature gradient occurs in a 

stratified lake; the metalimnion. 

 

Trihalomethanes  – a group of organic compounds with halide groups (Cl, Br, F) 

replacing hydrogen groups on a methane core, (e.g, CHCl

3

, CH

2

Cl

2

, CH

3

Cl). 

 

TOC  – total organic carbon; an aggregate measure of all organic matter, including 

dissolved and particulate occurring in the water. 

---

 

vii 

ACKNOWLEDGEMENTS 

 

This project has been a large team effort involving many individuals within the City of 

Phoenix, the CAWCD, and SRP.  Much of the early conceptualization of the project was 

developed in collaboration with Mike Gritzuk, Matt Palenica, Bob Hollander, Randy 

Gottler, and Jennifer Calles. We would also like to thank Dr. Bill Taylor and his 

colleagues at the Metropolitan Water District of Southern California for their advice on 

developing a rapid response system.  Within the Water Services Division, Walid 

Alsmadi (Project Manager), Edna Bienz, Natasha  Bernard, Alice Brawley-Chesworth, 

Paul Burchfield, Aimee Conroy, Tom Doyle, Ron Jennings, Francisco Gonzales, Keith 

Greenburg, Yu Chu Hsu, Maureen Hymel, Ron Jennings, Mike Lauer, Tom Martin, 

Shan Miller, Dick Musil, Paul Mally, Chris Rounseville, Mel Schlink, Raymond Schultz, 

Bonnie Smith, Jeff Van Hoy, Mike Welch, Kevin Williams, and Vic Vanderslice 

contributed to the project.  Many of the T&O management concepts outlined in this 

manual originated from these individuals.  Gregg Elliott, Bob Gooch, Brian Moorehead, 

Rick Prigg, Dallas Reigel from SRP; and Doug Cosby, Brian Henning, and Tim Kacerek 

from CAWCD contributed ideas, encouragement, and sometimes, sweat, to the project.  

Finally, we thank our ASU postdoctorial associates, graduate students, and technicians: 

Darlene Bruce, Qiang Hu, Mario Esparza-Soto, My-Linh Nguyen, Tom Dempster, 

Michelle Cummings, Kirsten Hintze, Mari Rodriguez, Samanth Dawson, Marisa Masles, 

and Dave Lowry for their ideas, analyses, and labor.

    

 

---

 

1 

SUMMARY 

 

 

The goal of this  Guidance Manual is to provide the water treatment community in the 

Phoenix area practical guidance on controlling tastes and odors in water supplies.  It 

was developed at the end of a three-year project, “Reducing Tastes and Odors and 

Other Algae-Related Problems for Surface Water Supplies in Arid Environments,” 

conducted by the City of Phoenix and Arizona State University.  The goal of the project 

was not only to investigate the T&O problem, but to implement control measures to 

reduce the T&O problem.  This goal was, in large measure, achieved.  Phoenix’s 

municipal water customers now receive better-tasting water than they did before the 

project began.  But more importantly, the project developed a scientific and 

management framework to guide future activities that will result in improved drinking 

water quality.   

 

This  Guidance Manual serves as a tool for T&O management programs in the Phoenix 

metropolitan area. Individual cities and regional groups of cities and agencies (Salt 

River Project, Central Arizona Water Conservation District, Arizona Department of 

Environmental Quality) and others can use this document to develop integrated 

strategies for minimizing taste and odor episodes in raw drinking water supplies.  

Individual water treatment plants can use this  document to treat/remove MIB and 

geosmin from raw water entering the plant.  Chemists and biologists can use this 

document to aid in detection of taste and odor compounds and identification of culprit 

organisms responsible for such compounds. 

 

This document is organized into six sections; the key  principles and objectives of the 

T&O management program are presented in Chapter 1.  Chapter 2 examines the 

spatial and temporal dimensions of the T&O problem.  Chapter 3 presents the 

multiple barrier concept  – the idea that a T&O management program should include 

“barriers” that extend from the watershed down through the water treatment plants and 

the distribution system.  This concept has long been used as the foundation for 

pathogen control in the water treatment field.  Chapter 3 also outlines the concept of a 

rapid response system that can provide water treatment personnel with the ability to 

respond quickly to T&O episodes.  Again, this is a borrowed concept, developed in 

consultation with the Metropolitan Water District of Southern California.  Chapter 4 

outlines a  prescribed monitoring program and some general predictions on the 

dynamics of the T&O situation in the Phoenix area.  Chapter 5 provides guidance on 

specific management practices that can be used to  control and manage T&O 

episodes.  This chapter includes sections on water supply operations, management of 

canals, source switching, and controls within water treatment plants.  Chapter 6 outlines 

the rationale  for  program assessment  and an approach for conducting continuing and 

annual program evaluations.  Finally, Chapter 7 presents three  case studies.  Each 

addresses a specific T&O episode that was encountered over the past three years.  

Each case study includes sections on monitoring results, diagnosis  of the problem, 

treatment selection, treatment application and follow-up monitoring.   

 

---