Computational Water, Energy, and Environmental Engineering, 2013, 2, 73-80
doi:10.4236/cweee.2013.22B013 Published Online April 2013 (http://www.scirp.org/journal/cweee)
Protecting Water Quality and Public Health Using a
Smart Grid
Ken Thompson1, Raja Kadiyala2
1Intelligent Water Solutions, CH2M HILL, Englewood, Colorado, USA
2Intelligent Water Solutions, CH2M HILL, Oakland, California, USA
Received 2013
ABSTRACT
After the attacks on September 11, 2001 and the follow-up risk assessments by utilities across the United States, secur-
ing the water distribution system against malevolent attack became a strategic goal for the U.S. Environmental Protec-
tion Agency. Following 3 years of development work on a Contamination Warning System (CWS) at the Greater Cin-
cinnati Water Works, four major cities across the United States were selected to enhance the CWS development con-
ducted by the USEPA. One of the major efforts undertaken was to develop a process to seamlessly process “Big Data”
sets in real time from different sources (online water quality monitoring, consumer complaints, enhanced security, pub-
lic health surveillance, and sampling and analysis) and graphically display actionable information for operators to
evaluate and respond to appropriately. The most significant finding that arose from the development and implementa-
tion of the “dashboard” were the dual benefits observed by all four utilities: the ability to enhance their operations and
improve the regulatory compliance of their water distribution systems. Challenge: While most of the utilities had sys-
tems in place for SCADA, Work Order Management, Laboratory Management, 311 Call Center Management, Hydrau-
lic Models, Public Health Monitoring, and GIS, these systems were not integrated, resulting in duplicate data entry,
which made it difficult to trace back to a “single source of truth.” Each one of these data sources can produce a wealth
of raw data. For most utilities, very little of this data is being translated into actionable information as utilities cannot
overwhelm their staffs with manually processing the mountains of data generated. Instead, utilities prefer to provide
their staffs with actionable information that is easily understood and provides the basis for rapid decision-making. Smart
grid systems were developed so utilities can essentially find the actionable needle in the haystack of data. Utilities can
then focus on rapidly evaluating the new information, compare it known activities occurring in the system, and identify
the correct level of response required. Solution: CH2M HILL was engaged to design, implement, integrate, and deploy
a unified spatial dashboard/smart grid system. This system included the processes, technology, automation, and gov-
ernance necessary to link together the disparate systems in real time and fuse these data streams to the GIS. The overall
solution mapped the business process involved with the data collection, the information flow requirements, and the sys-
tem and application requirements. With these fundamentals defined, system integration was implemented to ensure that
the individual systems worked together, eliminating need for duplicate data entry and manual processing. The spatial
dashboard was developed on top of the integration platform, allowing the underlying component data streams to be
visualized in a spatial setting. Result: With the smart grid system in place, the utilities had a straightforward method to
determine the true operating conditions of their systems in real time, quickly identify a potential non-compliance prob-
lem in the early stages, and improve system security. The smart grid system has freed staff to focus on improving water
quality through the automation of many mundane daily tasks. The system also plays an integral role in monitoring and
optimizing the utilities’ daily operations and has been relied on during recovery operations, such as those in response to
recent Superstorm Sandy. CH2M HILL is starting to identify the processes needed to expand the application of the
smart grid system to include real-time water demands using AMI/AMR and real-time energy loads from pumping fa-
cilities. Once the smart grid system has been expanded to include Quality-Quantity-Energy, CH2M HILL can apply
optimization engines to provide utility operations staffs with a true optimization tool for their water systems.
Keywords: Smart Grid; On-line Water Quality Monitoring; OWQM; Event Detection System; EDS; TEVA-SPOT
1. Introduction
Continuous monitoring of distribution system water
quality was rarely conducted prior to the terrorist attacks
of September 2001 on the United States. Following those
events and the completion and review of risk assessments
for all public water systems (PWSs) serving a population

K. THOMPSON ET AL.
74
greater than 3,300, the distribution system was identified
as the most vulnerable area of attack.
Homeland Security Presidential Directive 9 required
the U.S. Environmental Protection Agency (EPA) to de-
velop a process for utilities to improve the protection of
their water distribution systems. In response, distribution
system water quality monitoring pilot projects were
conducted, which were funded by the EPA Water Secu-
rity Division Water Security (WS) initiative. [1] As a
result, continuous monitoring systems are in operation in
Cincinnati, Dallas, New York, Philadelphia, and San
Francisco. Independent from the WS initiative program,
some PWSs and U.S. government agencies have been
developing similar programs. Benefits of these systems
include improvement of water treatment processes, in-
creased efficiency of water utility operations, more as-
sured quality of water delivered to consumers, and in-
creased protection of public health.
2. Benefits of Distribution System
Monitoring
Benefits from continuous distribution system on-line
water quality monitoring (OWQM) may be categorized
as operational enhancements, regulatory compliance, and
contamination warning.
Operational enhancements include continuous indica-
tion of water quality in the distribution system beyond
that which is possible through routine regulatory sam-
pling. Early indication may be provided of unusually low
residual chlorine levels, impending nitrification (elevated
ammonia), turbidity excursions caused by main breaks,
and other unusual water quality changes. This monitoring
is achieved through measurement of several water quality
parameters with which water utilities are already familiar
(e.g., chlorine residual) and other parameters that are
relatively new to this application (e.g., total organic car-
bon).
Regulatory compliance benefits of OWQM include
improving the ability to maintain chlorine residual as part
of the Total Coliform Rule (TCR) [2] and maintaining
proper pH control to avoid potential violations of the
Lead and Copper rule [3].
Warning of intentional or unintentional contamination
in the distribution system is somewhat more complex.
Specialized analyzers are available, including gas chro-
matographs that may detect specific contaminants and
toxicity monitors of many types that can provide a gen-
eral warning of contamination. Due to the large number
of potential contaminants, rather than attempting to spe-
cifically identify a contaminant, it is more practical to
monitor for an indication of contamination through
changes in many of the same water quality parameters, or
surrogates, that are used for operational benefit monitor-
ing.
Beyond monitoring for operational and contamination
purposes, utilities should consider OWQM as part of the
Distribution System Optimization program of the Part-
nership for Safe Water [4]. The Partnership is a voluntary
effort between EPA, the American Water Works Asso-
ciation (AWWA), several other drinking water organiza-
tions, and more than 200 water utilities throughout the
United States. The goal of the Partnership is to provide a
new measure of safety to millions of Americans by imple-
menting prevention programs where legislation or regula-
tion does not exist to do so. The preventative measures
are focused on optimizing treatment plant performance
and distribution system operation.
3. Selection of Water Quality Parameters
A water utility that is embarking on design of distribution
monitoring must first decide which water quality pa-
rameters to monitor. Parameters that are typically in-
cluded in OWQM systems include:
 Total organic carbon (TOC)
 Residual chlorine
 Conductivity
 pH
 Turbidity
These parameters are of interest to utilities from a dis-
tribution system operational and regulatory perspective
and provide critical information including:
 TOC – Elevated turbidity excursions can be associ-
ated with a breakthrough at the water treatment plant
(WTP) or scouring and release of biofilm within the dis-
tribution system.
 Residual chlorine – A sudden loss in residual could
promote biofilm growth and potential violation of the
TCR.
 Conductivity – This measurement provides an easy
method for identifying mixing or different water sources,
which can have a significant impact on many industrial
operations.
 pH – pH is controlled for disinfection and corrosion
control. The formation of some disinfection byproducts
is pH dependent.
 Turbidity – This parameter provides warning of a
system disruption created by a surge or reversal in flow
that scours the pipeline. This could be caused by a pipe-
line break, hydrant knockover, or other problems that
will impact chlorine residual and customer satisfaction.
Utilities that use chloramines for disinfection also meas-
ure for ammonia, nitrates, and dissolved organic carbon
(DOC) to provide early warning of nitrification in the
distribution system. The first water quality indicator of
nitrification will be the increase of ammonia, which will
occur before nitrites and nitrates begin to increase.
The myriad potential contaminants have been classi-
fied among twelve categories by EPA [5]. Laboratory

K. THOMPSON ET AL. 75
testing has concluded that three of these water quality
parameters—TOC, residual chlorine, and conductiv-
ity—respond to the presence of contaminants from ten of
the twelve categories, so along with operational moni-
toring, broad contaminant coverage is also provided with
a minimum of instrumentation. The relative change in
quality of water with either chlorine or chloramines has
been investigated by EPA and the pilot cities to serve as
a general guidance for evaluating a water quality anomaly.
Most OWQM systems include monitoring for absorb-
ance of ultra-violet (UV) light. UV analyzers, which op-
erate by measuring absorption at the single 254-nano-
meter (nm) wavelength, are generically referred to as
UV-254 analyzers. Instruments that operate through
analysis of a broad spectrum from 200 to 720 nm are
referred to as spectral analyzers.
UV absorbance has been shown to be strongly corre-
lated to TOC content [6]. UV-254 analyzers measure
absorbance at the 254-nm wavelength as this is the radia-
tion emitted by a common mercury-based UV source
lamp. The absorbance of UV light by TOC or other con-
taminants contained within the water sample is reported
as a percent of the uninhibited lamp intensity, ranging
from 0 to 100 percent.
Spectral analyzers utilize a xenon lamp to produce a
light source across UV and visible light wavelengths
from 200 to 720 nm. Measurement of absorbance at 254
discrete wavelengths across this range enables construc-
tion of an absorbance, or spectral, curve (Figure 1). Due
to the substantially greater information provided by
spectral analysis, the broadband spectrum enables meas-
urement of TOC based on calculation of the numerous
UV/visible light wavelengths that are associated with this
parameter. Similarly, turbidity is also calculated based on
analysis of numerous wavelengths. Subtraction of the
turbidity component enables derived measurement of
nitrate and DOC. Other parameters, not typically in-
cluded in OWQM analysis, also may be derived from
broad spectral absorbance of UV and visible light.
Figure 1. Ultraviolet/Visible Absorbance spectrum enables
calculation and derivation of numerous water quality pa-
rameters.
Not all sources of TOC are revealed by UV/visible
light absorbance, but a large enough percentage are de-
tected that these technologies are generally accepted for
the OWQM application. This limitation of correlated or
spectral indication of TOC must be considered when
selecting OWQM parameters.
4. Selection of Water Quality Analyzers
Once water quality parameters to be used for OWQM
monitoring are selected, specific instruments to be used
for this purpose must be selected. All utilities are under
pressure to minimize capital and operating costs, so this
consideration factors into analyzer selection. Addition of
OWQM monitoring must be done without unnecessarily
adding to the existing responsibilities of utility techni-
cians, also impacting the selection of OWQM analyzers.
One way to do this is to select sensors and analyzers that
are reliable and inexpensive to operate, and require only
infrequent direct attention or maintenance.
4.1. Chlorine Analyzers
The two most common methods for on-line chlorine
analysis are amperometric and colorimetric detection.
The colorimetric method requires use of chemical re-
agents to produce a reaction, which is measured and used
to quantify chlorine content. Reagent reservoir levels
must be regularly monitored and refilled by maintenance
personnel. Additionally, reagents used for colorimetric
tests have been found to degrade in environments that
exceed 105 degrees, significantly affecting the quality of
the analysis.
Amperometric sensors measure changes in electric
current or potential and operate without use of chemical
reagents. For monitoring residual chlorine by OWQM
systems, these sensors reduce maintenance costs and
activities, as well as operational risks from depletion of
reagent reservoirs between service visits. Therefore am-
perometric technologies are most frequently used.
4.2. TOC Analyzers
Traditional TOC analyzers involve multiple electro-
chemical reactions for operation. Phosphoric acid is used
for pH reduction and inorganic carbon removal, followed
by oxidation of organic carbon to CO2 by sodium or
ammonium persulfate and heat or UV light. At least one
manufacturer uses boron-doped electrodes to generate
oxidation radicals in place of the persulfate solution.
CO2 is directly detected by a non-dispersive infrared
(NDIR) detector, or converted to carbonic acid and
measured by conductance. Operation requires periodic
replenishment of acid and, if used, persulfate reagents.
The UV lamp, when used, also requires replacement.

K. THOMPSON ET AL.
76
Prefiltration of the analyzer sample stream is fre-
quently required to prevent plugging of the micro-tubing
that is included in the analyzer’s internal construction. In
some water that includes a substantial level of inorganic
carbon, additional filters to remove this carbon compo-
nent must be included at the inlet to the analyzer. These
filtering systems are generally available from the ana-
lyzer manufacturer, but constitute a maintenance activity
and additional cost that varies depending upon the par-
ticular nature of the sample stream.
Mechanically, TOC analyzers are highly complex and
require substantial technical training and experience to
ensure proper operation over extended periods [7]. While
analyzers that are mechanically less intricate are now
commercially available, they remain complex in opera-
tion.
4.3. UV Analyzers
When UV254 analysis is used for an OWQM system, the
absorbance measurement alone may be used as a general
indication of water quality. Due to the potential difficul-
ties involved with operating and maintaining TOC ana-
lyzers, UV analyzers are sometimes used to provide a
TOC measurement or indication, depending on the par-
ticular technology selected.
Several factors must be considered when selecting a
UV absorbance analyzer for use in OWQM systems.
Some UV254 analyzers apply a correlation coefficient
to the 254 nm absorbance reading to generate a TOC
measurement. However, the accuracy of the correlation is
dependent upon the stability of the correlation. For sys-
tems where the source water is subject to change, the
correlation may change, and without adjustment to the
programmed coefficient, the TOC measurement may be
inaccurate.
TOC correlation to UV254 absorbance is also impacted
by the turbidity of the sample stream. Some UV254 ana-
lyzers include automated turbidity compensation, while
others do not.
Spectral analyzers calculate TOC and turbidity meas-
urement from the UV and visible light absorption meas-
urements that make up the spectral curve. Turbidity
readings from these analyzers are applied to the TOC
calculation to achieve a turbidity-compensated TOC
measurement. These analyzers can also derive nitrate,
DOC and other water quality parameters. Specific water
contaminants (e.g., ricin [8]) can be calculated based on
their specific absorbance spectrum, similar to the method
used for TOC determination.
EPA studies have found that UV/visible light absorb-
ance-based TOC readings will not detect all TOC com-
pounds, but they do detect a large enough portion of po-
tential TOC contaminants that these instruments are valid
for contamination monitoring [9]. Similarly, TOC read-
ings by these instruments are suitable for indicating dis-
tribution system water quality because drinking water
TOC is typically made up of humic and fulvic acids,
which are very accurately detected by UV absorption.
Absorbance-based UV and TOC measurements have
the potential to be affected by deposition of mineral con-
tent on optical surfaces. Highly dependent on the water
being tested, mineral deposits on lenses will impact ab-
sorbance readings. Optically based analyzers frequently
include automated cleaning systems ranging from peri-
odic flushing with various solutions to mechanical wipers
or brushes, or continuous operation of ultrasonic wave
generators. These have been found to be of varying ef-
fectiveness.
Some UV-based optical analyzers include automated
compensation for variation of the UV lamp output over
time. This function is essential as lamp output is known
to decrease over time, requiring periodic lamp replace-
ment.
4.4. Ammonia Analyzers
Ammonia sensors may be reagent or non-reagent based.
For OWQM systems, reagentless technologies that use
ion-selective electrodes are preferred to minimize main-
tenance activities and costs.
The ammonia measurement should include pH com-
pensation, which may be integral to the ammonia sensor
or a separate pH sensor with signal input to the ammonia
analyzer. The pH signal can also be separately used for
the OWQM pH measurement. Ammonia sensors may
also include potassium compensation because elevated
potassium levels will interfere with low-level ammonia
measurements, such as those close to the sensor detection
limit where OWQM systems typically operate. The po-
tassium signal is not an OWQM parameter and is not
separately reported by the OWQM system.
4.5. Conductivity, pH, Turbidity Analyzers
These sensors operate using standard, proven electro-
chemical and optical technologies that water utilities
have deployed in WTPs and other facilities for many
years. Specific analyzers to be used in an OWQM station
should be those that the user has found to be reliable in
service and to provide accurate readings with minimal
maintenance requirements. For these parameters, use of a
utility’s standard sensors is usually acceptable.
5. Prioritization of Installation Locations
Selection of installation locations for OWQM stations
involves important considerations to reduce cost and
provide an environment conducive to long-term and suc-
cessful operations.
Monitoring stations are typically installed at the dis-

K. THOMPSON ET AL. 77
charge of each WTP or at wholesale connection interties
to indicate baseline conditions entering the distribution
system for comparison with downstream measurements.
These stations also indicate results of changes to the
treatment process and warn of conditions in the treatment
process that may otherwise go undetected. Some OWQM
process measurements may already be made at the WTP,
and these existing measurements can be used for OWQM
purposes. When adding other OWQM parameters that
are not already monitored at the WTP, some utilities use
installation of OWQM stations as an opportunity to up-
grade older instruments or to convert to reagentless
technologies to reduce labor and maintenance costs.
OWQM stations are frequently installed at the dis-
charge of distribution system reservoirs and chlorine
boosting pump stations. Measurement may be upstream
of chlorine addition to provide a measure of the quality
of the water in the reservoir and that further upstream.
The OWQM station could alternately be installed down-
stream of chlorine addition at a booster station to provide
a baseline measurement for comparison to OWQM sta-
tions further downstream.
OWQM stations can also be installed at critical nodes
in the distribution system, and different approaches may
be taken in selecting these locations. Distribution system
managers generally have a good understanding of the
operation of the piping network and can often identify
the nodes of interest based on experience. A more scien-
tific approach to OWQM siting is frequently conducted
through the use of the Threat Ensemble Vulnerability
Analysis and Sensor Placement Optimization Tool (TEVA-
SPOT) software [10]. This analytical package, developed
by EPA, Sandia Laboratories and others, analyzes a dis-
tribution system network and identifies critical nodes that
will represent water quality impacting the largest number
of consumers. TEVA-SPOT analysis results often vali-
date the operational understanding expressed by distribu-
tion system managers, but also frequently identify nodes
otherwise not understood to be critical or recommend
subtle location changes compared to the managers’ rec-
ommendations.
The analysis enables prioritization of a selected num-
ber of OWQM stations to meet the budget available for a
project and identify stations to be added as a monitoring
system expands over a period of years.
6. Requirements for Data Communication
and Analysis
Several products are available for analysis of OWQM data
and alarming of unusual conditions. The most common
software event detection systems (EDSs) are commer-
cially available through s::can, Whitewater, and Hach.
Also available is the Sandia National Laboratories free-
ware system Canary, which was developed as part of the
WS initiative. Each EDS has strengths and weaknesses
associated with its performance under distribution system
operations. Additional information can be obtained through
the EPA Water Security Division.
OWQM alarms are generally based on more than sim-
ple alarm setpoints for parameter measurements. Typi-
cally the alarms or alerts are associated with pattern
alarms, where multiple parameters change in a manner
that is atypical of their normal relationship. As an exam-
ple, if TOC increased, it would also be expected that
DOC would increase in a proportional manner. When a
utility implements enhanced coagulation, the TOC-to-
DOC relationship changes, generating an alert at the wa-
ter quality monitoring stations. Broadband UV/visible
systems also produce a spectral alarm that is initiated if
the normal spectral fingerprint displays an unusual shift.
OWQM data are collected more frequently than typi-
cal Supervisory Control and Data Acquisition (SCADA)
monitoring data, and therefore OWQM data usually
cannot be communicated over traditional low-bandwidth
SCADA networks. Additionally, spectral data cannot be
communicated over the typical SCADA data collection
network, so separate communication pathways must be
established. Many utilities, therefore, include all OWQM
data on the alternate path and keep monitoring and
maintenance of this information separate from opera-
tional SCADA data, although there is no requirement to
maintain this separation. If T-1 or optical connections to
the central monitoring facility are available, these path-
ways may be used, but typically the OWQM measure-
ments are still transmitted as a separate data stream from
SCADA parameters.
Water quality analysis is conducted locally at the OWQM
station, and measured values and alarms are communi-
cated to a central historian and display. Typically a long-
term database is used for storage and retrieval of data and
a short-term cache for short-term (30-day) trending.
For OWQM stations at water utility locations, the data
may be communicated over a virtual private network
(VPN) set up on the existing utility network, if available.
For locations that do not have access to the utility’s net-
work, data are frequently communicated over commer-
cial digital radio or cable service connections.
7. Fabricated On-line Water Quality
Monitoring Stations
Installed OWQM stations take several forms, depending
on the parameters and analyzers selected for use. Out-
door installations are generally fabricated in enclosed
cabinets for protection and security. Because water flows
inside the cabinet with an open drain, ventilation of the
cabinet is required to dissipate moisture that may accu-
mulate. In hot southern climates, temperatures inside the
enclosed cabinets are also of concern, so ventilation is

K. THOMPSON ET AL.
78
also necessary and shade from direct solar illumination is
recommended. High internal temperatures can also im-
pact the stability of chemical reagents, so reagentless
analyzers are also preferred.
Many of these issues may be avoided by installing
OWQM stations indoors. For secure indoor locations,
such as those owned and controlled by the utility, the
station may be configured as a wall-mount panel or open
frame system. Heat and moisture are usually no longer an
issue, but the potential for tampering or vandalism of
equipment may be more of a concern. Indoor locations
that are not owned by the utility, such as those at fire
departments, police stations, hospitals or other host fa-
cilities, should be configured as enclosed cabinets that
will still require ventilation to remove humidity. Indoor
locations avoid the OWQM environmental impacts of
excessive heat or cold, and also make it easier for utility
technicians to conduct routine calibration and service.
However, indoor installation at any facility requires that
access be available on a short-notice basis to retrieve
automatically collected water samples in the event poten-
tial contamination is detected. Continuous access is a
priority for locating OWQM stations that hold contami-
nation monitoring as a mission-critical consideration. For
those focused only on operational benefits, quick access
is less of a siting priority.
8. Operational Benefits
The most important aspect of OWQM systems are the
benefits of assured and improved water quality provided
to the consumer. Such monitoring may provide recom-
mendations for adjustment of the water treatment process
and feedback of the results of treatment process changes.
OWQM stations can provide early warning of water main
breaks, low or high chlorine conditions, nitrification, and
other conditions and thereby not only improve operations,
but can also save considerable costs to the utility.
When the EDS identifies an anomaly in a data stream,
an alert is sent to the centralized distribution system moni-
toring dashboard, which allows the operator to spatially
correlate information from other data streams (consumer
complaints, enhanced security alarms, public health
alerts) in real time. Operations staff can rapidly and in-
dependently query each alert to evaluate trends and relate
the anomalies to explainable events that may be occur-
ring in the water distribution system (e.g., a pipeline
break). During this operational evaluation, it is possible
that the cause of the alerts cannot be explained by known
activities. When this occurs, the utility can proceed with
a tiered response, i.e., a Consequence Management Plan,
that becomes increasingly aggressive as more informa-
tion related to a potential contamination event is re-
ceived.
The ability of rapidly converting very large data streams
into actionable information and providing the consoli-
dated alert information on a user-friendly dashboard sig-
nificantly decreases a utility’s response time. The ability
to identify trends and nuances in the data supports opera-
tional benefits not previously available. Examples of
collected data associated with distribution system events
are presented below.
Figure 2 is a plot of spectral absorbance that indicated
a peak characteristic of iron oxide. Plots of the data in
five-day increments showed the size of the peak was
progressively increasing. This trend was ultimately iden-
tified as accumulating deposition of iron on the analyzer
optics, caused by aggressive water unexpectedly leaching
from ductile iron pipe. Identifying and addressing the
problem early saved the utility an estimated $20 million
in early pipe replacement costs.
In Figure 3, DOC and TOC plots were used to opti-
mize granular activated carbon (GAC) filter performance.
In this case the utility developed correlations between
total trihalomethane (TTHM) production and effluent
DOC for use in determining when to change the GAC
and maintain system compliance. In this example the
utility reduced the annual replacement costs by $100,000
at each WTP.
Figure 4 illustrates how OWQM data can be used to
track water age. In this case, nitrate profiles were com-
pared over time to determine travel time between sites.
The data were validated through the utility’s calibrated
model and similar readings from other distribution sys-
tem locations were used to verify the hydraulic model.
Figure 5 shows an example of how spectral absorb-
ance changes indicated failure of treatment plant controls
early enough for the problem to be resolved before major
damage occurred. In this case, the failure allowed spent
brine solution to flow into the distribution system reser-
voir. The immediate result was a spectral change associ-
ated with the highly colored brine solution blocking the
Figure 2. On-line water quality monitoring ultraviolet ab-
sorbance spectrum enables identification of distribution
system accelerated corrosion.

K. THOMPSON ET AL.
79
Figure 4. On-line water quality monitoring data enables
comparison of nitrate profiles and hydraulic model verifi-
cation.
taminant is shown to be considerably diluted, with the
maximum absorption reduced to 30 to 40 percent and
spread over seven minutes. The event is seen to take a
total of four hours to pass the station from start of the
event to return to normal water quality.
Figure 3. On-line water quality monitoring dissolved or-
ganic carbon and total organic carbon plots used to opti-
mize treatment plant maintenance activities.
UV transmittance and creating a spectral alarm and noti-
fication. The graph on the left indicates normal absorb-
ance (blue trace at bottom, behind and coincident with
green trace). Over a period of several minutes, the ab-
sorbance increases, with maximum disruption indicated
by the orange and purple marks indicating high absorb-
ance of 30 to 50 percent for three minutes. Thirteen min-
utes after the start of the event, the condition was re-
solved, the brine solution had passed the monitoring sta-
tion, and the absorbance spectrum returned to normal
(green trace at bottom, coincident with the pre-event ab-
sorbance).
A military base that uses water from a local utility of-
ten had reports of water quality problems that could not
be readily attributed to a known cause. Monitoring of the
water inlet to the base identified changes in the water
supply as shown in Figure 6. The water provider occa-
sionally changed the source of the water and where it
entered the distribution system. The result was heavy
scouring in the pipe, directly impacting water quality on
the base. Once the problem was understood, the base was
able to work with the water provider to inform them of
the impact associated with flow reversals in the distribu-
tion system. The water provider also implemented a
flushing program to reduce the sediment that had accu-
mulated in the distribution system pipelines.
The right graph shows conditions the next day at
monitoring station in the distribution system. The con-
Figure 5. On-line water quality monitoring-identified changes in spectral characteristics indicate equipment failure.

K. THOMPSON ET AL.
80
Figure 6. On-line water quality monitoring system identifies changes in source water as the cause of water quality problems.
9. Operational Benefits
Installation and operation of OWQM stations at WTP
and reservoir outlets, and at strategic locations through-
out the distribution system provides an understanding of
water delivery conditions that may have been previously
unknown or incompletely understood. These systems
enable correction of problems and improvement in deliv-
ered water quality, provide added protection of public
health, and produce a substantial savings in operational
and maintenance/replacement costs. A mix of well known
and new technology sensors and analyzers may be used
to generate the substantial amount of data required for a
complete picture of distribution system operation. The
data can be displayed in an optimized manner on a cen-
tral dashboard as well as through mobile technologies to
support water utility operations.
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[1] CH2M HILL, “Contamination Warning System Demon-
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[2] EPA. (n.d.) “The Effectiveness of Disinfectant Residuals
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Office of Water, Office of Ground Water and Drinking
Water.
http://www.epa.gov/ogwdw/disinfection/tcr/pdfs/issuepap
er_effectiveness.pdf
[3] EPA, “Revised Guidance Manual for Selecting Lead and
Copper Control Strategies,” Washington, DC: US EPA
Office of Water, Office of Ground Water and Drinking
Water, 2003.
[4] AWWA. (n.d.) Partnership for Safe Water Program Fact
Sheet: Treatment Plant and Distribution System Optimi-
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