Overview of Distribution System Optimization (DSO)

Training

Presentation 1DSO Training

April 2015

Regions covered by TA’s

OEL Form

Water Treatment & DistributionOptimization Overview

History

Challenges

Approach

Optimization is About Public Health Protection

Initial focus of optimization was prevention of waterborne disease outbreaks related to microbial contaminants.

Giardia and Cryptosporidium routinely detected in water supplies and confirmed source of outbreaks.

Meeting existing compliance levels was not always effective for preventing outbreaks.

Multiple Barrier Concept in Water Treatment

Optimization requires treatment beyond regulatory levels.

Focus on multiple-barrier strategy to enhance water system performance. Particle removal (i.e., turbidity):

Coagulation/flocculation + sedimentation + filtration Disinfection

Sedimentation Barrier Filtratio

n Barrier Disinfection Barrier

Variable Quality Source Water

Turbidity Goal Turbidity

GoalDisinfectio

n Goal

Coagulant

Addition

Disinfectant Addition

Coagulation Flocculation Barrier

Disinfection Goal

High Quality Finished Water

Optimization Beyond Turbidity Focused on DBP Control

Stage 1 D/DBP Rule: Limits based on system-wide

running annual average.

Stage 2 D/DBP Rule (current): Limits based on running annual

average at specific sample sites.

New challenge to achieve microbial optimization goals while minimizing DBP formation.

EKY DS DBP PBT First DS DBP Series in KY (Pilot) June 2013-October 2014 6 Systems Complete

Campton Water System Hazard Water Department Knott County Water & Sewer District Manchester Water Works Martin County Water District No.1 Mountain Water District No.1—Marrowbone

DS DBP PBT

DS DBP PBT

EKY DS DBP PBT (cont.) 6 Sessions

Performance Goals & Monitoring Identifying Critical Sites Impacts of Storage Tanks on Water Quality Water Storage Tanks—Assessments & Special

Studies Flushing & Control Strategies Project Wrap-Up & Ongoing Optimization Activities

DS DBP PBT

EKY DS DBP PBT (cont.) Outcome

Goals have been established Operators know their systems better

Critical monitoring locations increase system monitoring Decrease in water age

Flushing Tank operational changes

These 6 systems have a plan going forward In conclusion…improvements in these distribution

systems have decreased water age and as a result have improved water quality!

Next Step – DSO With Multiple Utilities using a

1-Day Training Approach Performance based training (PBT) is an effective

approach for transferring priority setting and problem solving skills to a limited group of water systems (4 to 8 systems ideal).

This training intends to teach PBT concepts to more water systems using a modified approach:

DSO concepts will be introduced to a larger group of water systems as a 1-day training module.

Overcoming Challenges to Water Optimization

Changing Attitudes and Perceptions

Defining A Water Professional

Who is responsible for water quality (in the plant?; in the distribution system?)

What are the characteristics and attributes of these individuals

Summary

Distribution system optimization is a new field of learning for everyone.

Initial efforts focused on working with one utility at a time.

Performance Based Training is a proven approach for applying optimization principles to a group of water utilities.

A distribution system optimization 1-day training approach is being piloted to reach more water systems.

Why Optimize in the Distribution System?

Motivation for Optimizationand Performance Goals

Presentation #1BDSO Training

April 2015

Overview

Motivation for distribution system optimization

Optimization focus on water quality

Distribution system optimization goals

WHY?

The Motivation

Why Optimize the Distribution System? Public health protection:

On average, from 1971 to 2002, a distribution-related outbreak caused 152 illnesses, with the largest causing as many as 5,000 illnesses (Craun et al., 2006).

Public health risks include: Microbial contaminants (e.g., Salmonella, E. coli, Legionella, Naegleria

fowleri)

Chemical contaminants (e.g., organic, inorganic, disinfection byproducts ~ TTHMs, HAAs)

Secondary benefits: Proactive approach to meeting compliance.

Fewer complaints, happier customers!

Why Optimize in the Distribution System?

Alamosa, Colorado Case Study System Description

Serves 8,900 plus 1,000 through purchase systems Ground water with disinfection waiver… but is this really different from a

SW system that doesn’t maintain a residual? Three storage tanks (1 ground level) 50 miles of pipe

In compliance with all regulatory requirements, except arsenic Total coliform samples were

negative prior to the outbreak

Salmonella contamination Generally spread through human or

animal feces ~ rarely through drinking water

Suspected Cause of OutbreakInadequate Physical and Disinfection Barriers

Physical contamination of Weber Reservoir (ground storage tank):

o Cracks and holes could allow small animal or water (snow melt?) to contaminate the tank

o Evidence of wildlife near (but not inside) the tank

o Tanks supplied majority (~75%) of the system

o Salmonella contamination was found throughout the system

No disinfection barrier in the system!

Impacts of the Outbreak were Devastating!

Public Health: 442 illness reported (as many as 1,300 sick?); 20

hospitalized, 1 death

Community: All schools closed and most child care facilities

Several restaurants closed

Public Relations “challenge” for water system ~

3 weeks without safe water

Costs estimated around $1 Million to City, County

and State

Key Lessons Learned from Alamosa Doesn’t take much to impact an

entire system (suspect just 1 bird…) Routine coliform monitoring did not

indicate a problemo Consistent with other waterborne

disease outbreaks (Gideon, MO and Cabool MO)

A significant team (from all over Colorado) was needed to provide an alternate water supply, collect and measure WQ samples, make repairs, clean tanks, disinfect and flush the system, and notify citizens

The citizens and businesses were without safe drinking water for nearly three weeks

HOW?

Protecting Water Quality and Public Health

through Optimization

Distribution System: The Last Barrier(s) to Public Health Protection

Protecting the physical barrier/ infrastructure from contamination (e.g., maintaining pressure, preventing backflow, protecting storage tanks, etc.)

Providing a disinfection barrier against contamination and water quality deterioration

The Disinfection Barrier:What Research Says…

Importance of providing a disinfectant residual barrier: o Studies indicate that a free chlorine residual of 0.2 to 0.5 mg/L is

needed to provide adequate protection against microbial contamination (Baribeau, 2005).

o Systems that maintained free chlorine residual of greater than 0.20 mg/L had at least 50% lower rate of coliform occurrence (LeChevallier, 1996).

Importance of routinely monitoring disinfectant residual:o Free chlorine residual is an excellent indicator of microbial

contamination in the distribution system (Helbling and VanBriesen, 2008). In other words… chlorine residual verifies that the physical (and disinfection) barriers are in place.

The Disinfection Barrier: What We’ve Learned…

Area Wide Optimization Program (AWOP) distribution system work indicates:o Water systems aren’t monitoring throughout

their systems

o At critical sites, free chlorine residual is not maintained ≥ 0.2 mg/L.

The Flip Side: Disinfection Byproduct (DBP) Formation

DBPs are formed when chlorine (or other disinfectant) reacts with organics (total organic carbon) in the water

Formation is impacted by: Reactions within the bulk water (due to increased chlorine,

temperature, organics, etc.)

Reactions within the distribution system infrastructure (e.g., biofilm, etc.)

Water age (time)

Organic Matter (TOC)Chlorine

DBPs(TTHM & HAA5,

others)

Risks Must be Balanced

Increase Chlorine = Increase DBPs

Decrease Chlorine = Increase Microbial Risk

Bladder Cancer

Reproductive Disorder

Diarrhea

Kidney Failure

Hemolytic Uremic

Syndrome

Vomiting

Optimized Performance Starts by

Setting Water Quality Goals

Disinfection Performance Goal

Disinfection Goal:

Maintain ≥ 0.20 mg/L free chlorine

At all monitoring sites in the distribution system, at all times.

Regulatory Requirement is 0.20 mg/L free chlorine

DBP Performance Goals:Individual Site LRAA Goals

LRAA = locational running annual average.

Applies to the most recent four quarters of data (LRAA).

Requires a minimum of four quarters of DBP data at each sample site assessed.

Stage 2 D/DBP Rule MCL is 80 ppb for TTHM and 60 ppb for HAA5

Individual Site LRAA Goal:

TTHM LRAA ≤ 70 ppb

HAA5 LRAA ≤ 50 ppb

At all sample sites in the

distribution system

Plant Effluent

Individual Site LRAA goal must be met at all sample locations in the system.

TTHM Results (this site):Q2 05: 45 ppbQ3 05: 56 ppbQ4 05: 79 ppbQ1 06: 60 ppb

Meets performance goal (TTHM LRAA ≤ 70 ppb)

LRAA = 60 ppb

DBP Performance Goals:Long Term System Goals

Calculated by averaging past 8 quarterly LRAA values (highest LRAA each quarter used in calculation).

Requires 11 quarters of data for a site to be assessed.

Justification: provides safety factor for meeting Stage 2 regulations.

Long-Term System Goal:

Average of Max TTHM LRAA values ≤ 60 ppb

Average of Max HAA5 LRAA values ≤ 40 ppb

Applied throughout the system

Conclusions

The Alamosa outbreak and other recent water quality crises provided some valuable lessons on why optimization is important.

This training will focus on maintaining the distribution system barrier: Monitoring and maintaining the disinfection

barrier.

Monitoring DBPs (at compliance locations) to balance microbial and DBP risks.

ReferencesBaribeau, H., Gagnon, G., Hofman, R., and Warn, E. (2005). Impact of Distribution System Water Quality on Disinfection Efficacy.

AWWA Research Foundation, Denver, CO.

Centers for Disease Control and Prevention. (1991-2006). Surveillance for Waterborne Disease and Outbreaks Associated with Drinking Water and Water not Intended for Drinking. Morbidity and Mortality Weekly Report. Reports dated 1991-2006. From http://www.cdc.gov/mmWR.

Craun, M., Craun, G., Calderon, R., and Beach, M. (2006). Waterborne Disease Outbreaks in the United States. Journal of Water and Health, 04.Suppl 2, 2006. Retrieved August 14, 2009 from http://www.epa.gov/nheerl/articles/2006/waterborne_disease/waterborne_outbreaks.pdf.

Craun, G. and Calderon, R. Waterborne disease outbreaks Caused by Distribution System Deficiencies. Journal AWWA, September 2001.

U.S. EPA. 2007. Estimating the Burden of Disease Associated with Outbreaks Reported to the U.S. Waterborne Disease Outbreak Surveillance System: Identifying Limitations and Improvements. U.S. Environmental Protection Agency, National Center for Environmental Assessment, Cincinnati, OH. EPA/600/R-06/069.

Falco, R. and Williams, S. (November 2009) Waterborne Salmonella Outbreak in Alamosa, Colorado March and April 2008: Outbreak Identification, Response, and Investigation. From http://www.cdphe.state.co.us/wq/drinkingwater/pdf/AlamosaInvestRpt.pdf.

Helbling, D.E. and J.M VanBriesen, Continuous monitoring of residual chlorine concentrations in response to controlled microbial intrusions in a laboratory-scale distribution system. Water Research ,42(2008) 3162-3172.

LeChevallier, M.W., Welch, N.J, and D.B. Smith, Full-Scale Studies of Factors Related to Coliform Regrowth in Drinking Water, Applied and Environmental Microbiology, p. 2201-2211, July 1996.

National Research Council. (2006) Drinking Water Distribution Systems Assessing and Reducing Risks. Washington, DC: National Academies Press.

City of Alamosa 2008 financial report.

http://www.about-salmonella.com/salmonella_outbreaks/view/alamosa-colorado-municipal-water-system-salmonella-outbreak/).

Pueblo Chieftain article from May 2, 2008 “Cost figures for salmonella outbreak trickle in.”