Application No. A.14-07-006
Exhibit No. GS-165
Date: July 24, 2015
Witness: Katherine Nutting
BEFORE THE
PUBLIC UTILITIES COMMISSION
OF THE STATE OF CALIFORNIA
GOLDEN STATE WATER COMPANY
PHASE II - WATER QUALITY
ISSUES IN THE CITY OF GARDENA
TESTIMONY
KATHERINE NUTTING
Prepared by:
GOLDEN STATE WATER COMPANY
630 East Foothill Boulevard
P. O. Box 9016
San Dimas, CA 91773-9016
July 2015
GOLDEN STATE WATER COMPANY
PREPARED TESTIMONY
KATHERINE NUTTING
TABLE OF CONTENTS
Background and History of Water Quality Issues in the Southwest District .................2 Distribution System Flushing ............................................................................................ 11 SeaQuest™ Addition and Discontinuance ........................................................................ 14 Recent Water Quality Issues in the City of Gardena ........................................................ 17 Response and Investigation ............................................................................................. 21 Current Water Quality and Activities in the City of Gardena ......................................... 24 Accelerated Flushing Activities ......................................................................................... 24 Capital Improvements ....................................................................................................... 25 Water Quality Monitoring .................................................................................................. 27 Continued Response ........................................................................................................ 30 Communications ...............................................................................................................33 Regulatory Communication .............................................................................................. 33 Customer and Community Communications .................................................................... 34 Written Statements ........................................................................................................ 34 Flushing Notification....................................................................................................... 35 i
Community Meetings ..................................................................................................... 35 Other Meetings .............................................................................................................. 36 Written Correspondence ................................................................................................ 37 Media Engagement ........................................................................................................ 38 Future Work ....................................................................................................................... 39 ii
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GOLDEN STATE WATER COMPANY
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PREPARED TESTIMONY
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KATHERINE NUTTING
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(Q)
Please state your name, address and place of employment
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(A)
My name is Katherine Nutting. My business address is 1600 W. Redondo Beach
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Blvd., Suite 101, Gardena, California.
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(GSWC).
I work for Golden State Water Company
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(Q)
What is your job title and what are your responsibilities?
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(A)
I am the General Manager for the Southwest District of GSWC’s Region 2.
A
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summary of my responsibilities and qualifications is provided in Schedule 1
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following my testimony.
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(Q)
Please explain the nature of your testimony in this proceeding.
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(A)
On March 6, 2015, the Office of Ratepayer Advocates (ORA) filed a motion for a
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separate phase in this proceeding to consider water quality issues in the City of
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Gardena. On April 13, 2015 Administrative Law Judge Rafael L. Lirag (“ALJ Lirag”)
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issued a Scoping Memo ruling directing GSWC to serve additional and detailed
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testimony regarding the water quality provided to residents in the City of Gardena. I am
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sponsoring the portions of GSWC’s testimony submitted in response to ALJ Lirag’s
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ruling as it pertains to the background and history of the water quality issues in the City
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of Gardena, customer complaints received by GSWC, GSWC’s investigation into the
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water quality issues, its response to the issues both operationally and to customers,
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TESTIMONY OF KATHERINE NUTTING (Cont.)
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and future actions that GSWC is evaluating to prevent a recurrence of these water
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quality issues.
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(Q)
Please summarize what you will be discussing in your testimony.
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(A)
As described above, GSWC was directed to serve additional and detailed testimony
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regarding the quality of water provided to the residents of the City of Gardena. This
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testimony serves as such. The testimony will describe what GSWC has done in the
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past and continues to do to optimize water quality in the Southwest District (also
9
referred to as the Southwest system), both at its water sources and within the
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distribution system network. It will discuss how the Southwest system maintains
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compliance with all drinking water standards and is committed to continued compliance.
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It will depict the actions GSWC has taken to address recent water quality concerns
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raised by some residents of the City of Gardena, including GSWC’s efforts to
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communicate to and solicit feedback from our customers and the community as a
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whole. Finally, it will convey GSWC’s actions moving forward to maintain compliance
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and provide optimal water quality for our customers.
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It should be noted that that the water quality issues that have been experienced in the
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Southwest System are not related to exceedances of any maximum contaminant levels
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(MCLs) or other water contamination problems nor resulted in GSWC violating any
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primary drinking water standards.
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Background and History of Water Quality Issues in the Southwest District
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(Q)
Provide an overview of the distribution system and supply sources in GSWC’s
Southwest District.
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TESTIMONY OF KATHERINE NUTTING (Cont.)
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(A)
The Southwest District of GSWC is located in southwestern Los Angeles County and
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serves the cities of Gardena and Lawndale, and parts of the cities of Carson, Compton,
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El Segundo, Hawthorne and Inglewood, and unincorporated portions of Los Angeles
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County, such as Lennox, Athens, and Del Aire. The system serves approximately
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51,000 customers using a mixture of local groundwater and imported surface water.
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Potable water is distributed to customers through a large distribution system consisting
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of cast iron, asbestos cement, ductile iron, polyvinylchloride ( PVC), and steel pipe. A
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more detailed description of the distribution system piping infrastructure in the
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Southwest system is provided in the testimony of Robert McVicker.
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There are two primary water supply sources for the Southwest system: (1) imported
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surface water from the Metropolitan Water District of Southern California (MWD); and
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(2) groundwater that GSWC produces locally through a network of wells.
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The Southwest System is divided into 18 geographically based Water Quality Areas
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(WQAs). The WQAs were created because the water system is large and has few
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pressure zones. Identifying separate geographical areas makes referring to different
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portions of the distribution system easier and more convenient. A map showing the
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WQAs is provided below.
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TESTIMONY OF KATHERINE NUTTING (Cont.)
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(Q)
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Describe the general nature of the water quality issues that are experienced in the
Southwest System.
(A)
As stated above, it is important to note at the outset that the water quality issues that
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have been experienced in the Southwest System are not related to exceedances of any
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MCLs or other water contamination problems that have resulted in exposure of
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customers to unsafe levels of contamination. In fact, the groundwater sources utilized
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in the Southwest System meet and have always met all primary drinking water
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standards, as have our imported water sources. Rather, the water quality issues that
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TESTIMONY OF KATHERINE NUTTING (Cont.)
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have been experienced in the Southwest System relate to negative aesthetic effects
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such as discoloration and odor.
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The cause of the discoloration and odor issues is primarily related to the nature of the
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groundwater in the geographic area of the Southwest System. In particular, the
6
groundwater in the underlying aquifer can contain high levels of naturally-occurring
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constituents such as ammonia, hydrogen sulfide, iron and manganese. While GSWC
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currently employs groundwater treatment systems to remove these constituents (as
9
described in more detail below), some areas of the Southwest system contain legacy
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manganese1 that accumulated prior to wellhead treatment addition. Also, wellhead
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treatment systems remove iron and manganese to below secondary MCLs (SMCLs),
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but trace amounts may still exist in the treated water. Finally, some Southwest sources
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contain manganese below the SMCL, but at levels high enough to accumulate in the
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distribution system. Thus, the finished water in the Southwest System is prone to
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containing trace amounts of iron, manganese or other constituents that can cause water
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quality issues.
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Water systems commonly provide a residual disinfectant in the distribution system to
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control microbial growth in the distribution system pipes. The most commonly used
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residual disinfectants are free chlorine and chloramines. Free chlorine is a stronger
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disinfectant, but chloramines are longer lasting and produce fewer regulated disinfection
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by-products. MWD has been using chloramines as a residual disinfectant for
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approximately 30 years. As described later in this testimony, the Southwest system
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1
Legacy of Manganese Accumulation in Water Systems: Literature Review, Water Research Foundation, 2013.
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TESTIMONY OF KATHERINE NUTTING (Cont.)
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originally employed free chlorine as a residual disinfectant but has since converted its
2
wells to chloramines.
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4
Chloramines are formed when free chlorine and ammonia are combined in water. To
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maintain the desired chloramine composition, it is important to maintain a chlorine-to-
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ammonia ratio of 4 or 5 to 1.2 At this ratio, most of the chloramines are composed of
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monochloramine, which is the preferred species due to its disinfection abilities and
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stability. Below this ratio, not all ammonia has combined with the free chlorine, thus
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free ammonia exists in the system, which can cause water quality problems. Above this
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ratio, di- and tri-chloramines are formed, which themselves can create undesirable taste
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and odor in the distribution system.
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Iron and manganese, even at trace levels, can react with the chloramine disinfectant in
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the distribution system. This is known as chlorine (or chloramine) demand. The metals
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actually react with the chlorine portion of the chloramines, thereby releasing free
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ammonia, which changes the chlorine-to-ammonia ratio. The presence of free ammonia
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can cause nitrification. Many systems around the world experience intermittent
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nitrification when chloramination is used for disinfection.3 Nitrification occurs when
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microorganisms, which are naturally present in the environment, reduce ammonia in the
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distribution system, which causes a further degradation of the chloramine residual.
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Lowered chloramine residuals can lead to conditions that create color and/or odor in the
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2
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3
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Microbiology, November 1991, p. 3399-3402
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Optimizing Chloramine Treatment Second Edition, AWWA Research Foundation, 2004, p. 7
Cunliffe David, A, Bacterial Nitrification in Chloraminated Water Supplies, Applied and Environmental
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TESTIMONY OF KATHERINE NUTTING (Cont.)
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distribution system. It is important to note that even if these trace levels of iron and
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manganese meet the secondary MCLs, they can still react with chloramine such that
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lower than desirable levels of chloramine can exist in the distribution system.
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Another effect of the naturally-occurring iron and manganese in the underlying
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groundwater is that these constituents can precipitate out of water in the distribution
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system, creating iron and manganese oxide particulates that accumulate in the pipes
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over many years; this can lead to discolored water events when the direction or volume
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of water flow changes suddenly in the distribution system, and the particles are stirred
up and/or break free from the pipes and enter customer services.
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(Q)
Southwest system.
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Describe the actions GSWC has taken in the past to address water quality issues in the
(A)
GSWC has engaged in a sustained and comprehensive effort to improve and maintain
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the water quality in the Southwest system over the course of many years. The focus of
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these efforts has been to target the causes of and solutions for lowered disinfectant
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residuals and discolored water, which occasionally includes water with particles and
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odor. In fact, GSWC has closely examined and studied these water quality problems
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over the course of the last two decades in order to ensure that the causes of the
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problems are fully understood, and the best solutions are put in place.
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Specifically, GSWC engaged CH2MHill in 1996 to investigate possible nitrification
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issues in Southwest. Nitrification was suspected since at the time GSWC combined
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chlorinated well water with chloraminated water imported from MWD. GSWC also
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discovered at this time that several wells had naturally-occurring ammonia, which
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TESTIMONY OF KATHERINE NUTTING (Cont.)
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means that chloramines were being inadvertently formed by the addition of chlorine, but
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not at the proper chlorine-to-ammonia ratio to form monochloramine.
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Another study was conducted by CH2MHill in 2007. The report is entitled Southwest
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System Water Quality Study. The 2007 study recommended process control
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improvement for chloramination including flow pacing chemical additions so that
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chemical doses would automatically adjust in response to flow changes, as well as tank
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operational improvements to reduce water age. The 1996 and 2007 CH2MHill reports
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are included as Attachment 1. Based on the results of the CH2MHill studies, GSWC has
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implemented several improvements in the Southwest System. In summary, these
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measures include: (1) chlorination system modifications; (2) installation of data
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telemetry systems; (3) wellhead treatment; and (4) chemical process control
13
improvements. These measures are each described in detail below.
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Chlorination System Modifications
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The well chlorination systems for all active groundwater sources were converted from
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chlorine to chloramines approximately 15 years ago. Chloramines are known to be a
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more effective disinfectant at controlling biofilm in the distribution system in many
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scenarios.4 Biofilm forms when naturally-occurring bacteria adhere to surfaces in moist
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environments. Biofilm is not uncommon in drinking water distribution systems. Though
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not harmful, it is desirable to control biofilm growth because if uncontrolled it can slough
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off and enter the water received by customers. This affects the visual aesthetic quality
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of the water and can also cause the water to have an odor. In addition, the presence of
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4
Optimizing Chloramine Treatment Second Edition, AWWA Research Foundation, 2004, p. 54
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TESTIMONY OF KATHERINE NUTTING (Cont.)
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naturally-occurring ammonia in many of the Southwest System wells made the use of
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free chlorination as a disinfectant challenging, since significant amounts of chlorine are
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required to oxidize the naturally-occurring ammonia. When free chlorine is added to
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water containing naturally-occurring ammonia, the chlorine and ammonia combine to
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form chloramines. To produce a free chlorine residual, a concentration of chlorine 9 to
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10 times greater than the concentration of ammonia is needed. Additionally, the
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kinetics of the chemical reaction takes time, and without sufficient contact time water
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entering the distribution system could contain a chemically unstable mixture of
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ammonia, free chlorine, and chloramines, which can lead to water quality challenges in
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the distribution system.
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By utilizing chloramines as the residual disinfectant, the naturally-occurring ammonia
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could be directly combined with chlorine to produce chloramines and decrease the
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amount of free available ammonia available as a food source for naturally-occurring
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nitrifying bacteria. This ultimately further reduced the chloramine demand in the
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distribution system and helped to limit biofilm growth.
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Installation of Data Telemetry Systems
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Data telemetry was installed at all plant sites, including wells and storage tanks.
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Greater understanding and control of treatment and residual disinfection processes was
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achieved using the implemented telemetry system. It also enabled better control of
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reservoir operations. GSWC continues to install additional telemetry functionality to
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provide further real-time information on source water and distribution system operations.
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Details of additional projects proposed in the current General Rate Case (GRC)
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TESTIMONY OF KATHERINE NUTTING (Cont.)
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proceedings and additional projects being considered are provided in the testimony of
2
Robert McVicker.
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Wellhead Treatment
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Iron, manganese, and hydrogen sulfide treatment was added to wells that exceeded
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SMCLs for iron, manganese, and/or odor. Implementation of these treatment processes
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greatly improved the aesthetic water quality by removing iron and manganese which
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can cause colored water events and by removing odor-causing hydrogen sulfide from
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the water. Removal of iron and manganese from groundwater sources would also
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reduce iron and manganese oxide accumulation in the distribution system, since these
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compounds are no longer being introduced into the water entering the distribution
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system.
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Chemical Process Control Improvements
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The process for adding chlorine and ammonia to produce chloramines as a residual
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disinfectant was optimized by flow pacing chemical addition. This made it easier to
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maintain the desired 4-5 to 1 chlorine-to-ammonia ratio. With the addition of flow pacing,
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as the pumping rates of the wells increase or decrease the chemical injection pumps
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automatically increase or decrease proportionally, thereby maintaining a consistent
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dosage ratio of chlorine and ammonia. Flow-paced dosage should lead to production of
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more stable chloramines, as well as a decreased potential for excess ammonia in the
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distribution system, since the desired chlorine to ammonia dosage is maintained.
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GSWC is now considering enhancing this process to provide for control of the ammonia
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dose using real-time free chlorine residual monitoring, which would increase our ability
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to maintain the desired chloramine composition. Other enhancements may be
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TESTIMONY OF KATHERINE NUTTING (Cont.)
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considered as part of the water quality analysis project that is described in the testimony
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of Robert McVicker.
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Distribution System Flushing
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5
(Q)
the Southwest System?
6
7
Are there any other measures that GSWC employs to address water quality issues in
(A)
Yes. In addition to the specific measures described above that deal with addressing
8
iron, manganese and other constituents in the groundwater sources for the Southwest
9
System, GSWC also routinely engages in distribution system flushing as a means of
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preventing and mitigating water quality issues in the system. Flushing is performed
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when water quality challenges such as colored water, odor and/or decreased
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disinfectant residual are detected. It is also used proactively to prevent such water
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quality challenges from occurring. Flushing is a regular practice performed by all well-
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managed water systems and is encouraged by the Division of Drinking Water (DDW) to
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improve and maintain system water quality. There are two common types of distribution
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system flushing: conventional flushing and unidirectional flushing (“UDF”). Conventional
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flushing consists of opening hydrants or flush-outs in a specific area of the distribution
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system and does not require valve isolation. Conventional flushing is conducted at low
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velocities and results in minimal scouring of the pipes. UDF, on the other hand, is
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conducted at much higher velocities in order to achieve scouring of the pipes.
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UDF consists of isolating a particular pipe section or loop, typically through closing
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appropriate valves and creating a single-direction flow which increases the maximum
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possible flushing velocity in the water main. UDF always progresses from a clean
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source and already flushed pipes systematically toward the end of the area to be
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TESTIMONY OF KATHERINE NUTTING (Cont.)
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flushed and generally follows the normal direction of water flow in the distribution
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system. Industry studies have suggested that UDF is more effective than conventional
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flushing under the conditions that are experienced in the Southwest distribution system,
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namely an abundance of unlined cast iron and steel pipes and the presence of
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biofilm.5,6
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Extensive planning and the use of a hydraulic model are critical for UDF. Following the
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normal water flow direction in the distribution system from a water source can
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necessitate completing UDF in large portions of the distribution system in order to
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complete UDF in one specific target area. An example of a UDF plan is provided as
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Confidential Attachment 16.
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Flushing involves discharging potable water to the storm drain system. GSWC flushing
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activities are performed in full compliance with state and federal regulations, including
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the Clean Water Act. GSWC has National Pollution Discharge Elimination System
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(NPDES) Permit coverage for all its discharges and is fully in compliance with the
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requirements. As required by the permit, appropriate treatment is applied to discharges
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to minimize the environmental impacts and whenever possible Golden State puts water
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from its flushing program to multiple uses prior to discharge.
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GSWC co-authored the Best Management Practices (BMP) manual to address and
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minimize the environmental impact of discharged water that has been adopted by the
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Investigation of Pipe Cleaning Methods, AWWA Research Foundation, 2003
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Establishing Site-Specific flushing Velocities, AWWA Research Foundation, 2003
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TESTIMONY OF KATHERINE NUTTING (Cont.)
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State Water Resources Control Board (SWRCB) as the statewide standard. Golden
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State was also instrumental in the development and passage of the new Statewide
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NPDES permit for drinking water discharges. Golden State worked for three years, hand
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in hand with the SWRCB, to develop industry support for a permit that was protective of
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the environment.
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GSWC began to implement a UDF program in the Southwest system in 2010. Because
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of the large size of the Southwest System, GSWC plans and performs its flushing
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program based on the individual WQAs that make up the overall Southwest System.
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The program has proven to be effective in improving water quality in the distribution
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system. For example, the first area where UDF was conducted was WQA 2, which
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serves a portion of the City of Hawthorne. Before conducting UDF in WQA 2, the
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detection of low chloramine residuals coupled with increased nitrite concentrations
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indicated that nitrification was occurring. UDF greatly improved the distribution system
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water quality in WQA 2. One metric that showed this improvement was the dramatic
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decrease in water quality complaints in this area. This is shown below by the decrease
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in total system complaints from 2010 to 2011; the decrease is primarily attributable to a
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decrease in complaints in WQA 2.
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System-Wide Customer Complaints – All Water Quality:
2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014
213
412
415
301
174
241
301
323
314
475
343
204
175
346
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GSWC continues to implement UDF where pipeline scouring is desired and
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conventional flushing has not been effective. Overall, as UDF is completed in each
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TESTIMONY OF KATHERINE NUTTING (Cont.)
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WQA, the frequency of water quality complaints decreases. From the initiation of the
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UDF program in May 2010, water quality complaints decreased every year until 2014.
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In 2015 additional resources (flushing crews, engineering, and administrative support)
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were put in place to perform UDF to a larger area of the distribution system more
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quickly.
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It is important to note that, while this technique is an industry best practice, there are
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conditions where scouring velocities cannot be achieved or where materials, such as
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corrosion byproducts, are adhered such that even very high velocities cannot fully
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remove them. GSWC continuously evaluates the best options to address these
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challenges. Alternatives to flushing are described later in this testimony.
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SeaQuest™ Addition and Discontinuance
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(Q)
water quality in the Southwest System?
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Are there any other operational strategies that GSWC employed in an effort to optimize
(A)
Yes. GSWC employed the use of SeaQuestTM in an effort to improve distribution system
water quality.
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(Q)
Describe the use of SeaQuestTM in the Southwest system.
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(A)
GSWC began phasing-in the addition of a sequestering agent (polyphosphate;
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SeaQuest™) to groundwater and surface water connections in 1999. Phosphate-based
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chemicals such as SeaQuestTM are used as corrosion inhibitors, as well as to sequester
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metals such as iron and manganese. Sequestering metals keeps them in solution so
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that they won’t precipitate and cause discolored water. The corrosion inhibiting qualities
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of the chemical could help to inhibit corrosion of the unlined iron and steel pipes, which
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TESTIMONY OF KATHERINE NUTTING (Cont.)
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could lessen disinfectant demand, as corrosion byproducts react with chloramine. It
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was thought that using a phosphate-based chemical such as SeaQuestTM, would help
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stabilize water quality by improving chloramine residuals, thereby leading to fewer water
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quality issues such as nitrification and taste and odor complaints.
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Beginning on June 17, 1999, a one year pilot study was conducted. SeaQuest™ was
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added to Goldmedal, Southern, 129th and Doty Well Plants, and MWD connection WB-
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25. The pilot study concluded that SeaQuest™ was effective at stabilizing water quality.
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A permit amendment was issued in January 2001 to add SeaQuest™ to water sources
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in the Southwest District for the following purposes: (1) control pipeline corrosion; (2) to
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control biofilm growth; (3) to mitigate low residual; and (4) to restore hydraulic carrying
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capacity.
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Despite the use of SeaQuest™, GSWC continued to experience chloramine residual
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degradation and customer complaints in many areas of the distribution system.
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CH2MHill examined the use of SeaQuestTM as part of their 2007 study. The July 2007
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CH2MHill report concluded “The addition of SeaQuest™ to the Southwest System water
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supplies provides little or no benefit in terms of maintaining chloramine residuals of at
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least 0.5 mg/L in the distribution system.”
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In 2010, GSWC implemented the UDF program to increase chloramine residual, reduce
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biofilm, and thereby decrease customer complaints. The program has been successful;
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customer complaints have steadily decreased, and chloramine residuals have generally
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increased in the areas where UDF has been performed. GSWC concluded that an
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TESTIMONY OF KATHERINE NUTTING (Cont.)
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ongoing UDF program was a more effective means of maintaining high water quality in
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the distribution system than the addition of SeaQuest™.
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4
In July 2012 GSWC submitted a Permit Amendment Application requesting the
5
cessation of SeaQuest™. The source water was determined to be non-corrosive and
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UDF was determined to be the most effective tool for controlling biofilm, increasing
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chloramine residual and restoring hydraulic carrying capacity. This was supported by
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the September 24, 2012 report by Frank Baumann who was hired by the California
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Department of Public Health’s Drinking Water Program (now the Division of Drinking
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Water [DDW] under the State Water Resources Control Board) to evaluate the request.
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Mr. Baumann also noted that the phosphate additions apparently not only have not
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prevented biofilm problems, the added nutrient may even have contributed to biofilm
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formation.
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DDW expressed concerns about discontinuing SeaQuest™ throughout the distribution
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system, and so a six-month pilot study during which SeaQuest™ would be stopped in
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the areas where UDF had been performed was approved. At the end of the study
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period of October 1, 2012 to March 31, 2013 GSWC prepared and submitted a report
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entitled Pilot Study to Discontinue SeaQuest, dated July 2013. The report summarized
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the results of the water quality monitoring conducted during the pilot study and the
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number of water quality complaints during that time.
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The report concluded that there were no significant changes after use of SeaQuest™
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was discontinued and no significant changes in water quality parameters that would
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indicate an increase in corrosion in the distribution system occurred after use of
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TESTIMONY OF KATHERINE NUTTING (Cont.)
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SeaQuest™ was discontinued. UDF had been completed in the areas of the pilot study
2
and therefore the biofilm mass had been removed or greatly reduced. Therefore, the
3
contribution of SeaQuestTM to the potential growth of biofilm in the distribution system
4
was not observed following UDF.
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Following subsequent discussions, the DDW approved SeaQuest™ cessation at the
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sources located within each water quality area after UDF was completed in that water
8
quality area.
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Currently, GSWC is required to add SeaQuest™ to the Belhaven, 129th Street, and
11
Compton Doty Well Plants. As part of our long-term plan to maintain good water quality
12
in the system, we have requested DDW approval to discontinue the addition of
13
SeaQuest™ at all water sources.
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Recent Water Quality Issues in the City of Gardena
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(Q)
Gardena in 2014.
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Describe the recent water quality issues in Gardena that began to emerge in the City of
(A)
During the second half of 2014, GSWC observed an increase in water quality
19
complaints and a corresponding decrease in chloramine residual in portions of the City
20
of Gardena. As shown in the table, water quality complaints increased and decreased
21
over several months during the second half of 2014 in the City of Gardena.
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26
27
28
17
TESTIMONY OF KATHERINE NUTTING (Cont.)
Number of Water Quality
1
2
Month – Year
Complaints in the City of
Gardena*
3
4
July 2014
12
5
August 2014
35
6
September 2014
13
7
October 2014
36
8
November 2014
7
9
December 2014
30
10
January 2015
33
11
February 2015
46
12
*These numbers differ from the information provided in ORA Data Request JA-009, as those numbers
13
reflected the number of complaints in the “Gramercy Place” area, identified as a 0.25 mile radius of Mrs.
14
Morita’s residence.
15
16
Upon observation of the increase, in the fall of 2014, Water Quality and Operations staff
17
initiated discussions and investigations on potential cause(s) of the increased
18
complaints. Weekly meetings were initiated in October 2014 to discuss the status of the
19
system and strategize on appropriate actions to improve water quality in the impacted
20
area. It was determined that UDF was the most appropriate course of action to improve
21
water quality in this portion of the distribution system. UDF had not previously been
22
performed in this area, which is identified as WQA 5, thus plans needed to be
23
developed. This took some time, but UDF began in WQA 5 on December 17, 2014.
24
25
26
27
28
18
TESTIMONY OF KATHERINE NUTTING (Cont.)
1
(Q)
Gramercy Place residence in the City of Gardena in early 2015.
2
3
Describe the specific water quality complaints that GSWC received from the South
(A)
On the evening of January 21, 2015 GSWC received a complaint of discolored water at
4
the residence located at 14903 South Gramercy Place in Gardena, California. This
5
address is located in WQA 5. A distribution operator responded to the complaint when
6
it was received. The same customer at the residence located at 14903 South Gramercy
7
Place reported discolored water in her home again on the evening of February 11,
8
2015. GSWC immediately dispatched an operator to investigate.
9
10
(Q)
South Gramercy Place.
11
12
Describe the actions taken by GSWC to address the complaints received from 14903
(A)
As described in GSWC’s response to ORA’s data request JA-009, Question 2 (a portion
13
of which is included as Attachment 2), GSWC took the following actions in response to
14
the January 21, 2015 complaint:
15
16
“An operator visited Ms. Morita’s residence on January 21, 2015. He observed
17
discolored water in the sink and toilet. Mrs. Morita told the operator that her neighbor
18
across the street had the same issue. The operator also visited that residence and
19
observed some discolored water in the sink and toilet. The operator flushed each
20
customer’s internal plumbing until the discolored water cleared, and the hydrant nearest
21
Ms. Morita’s residence was also flushed. Since that time, discussions with Ms. Morita
22
and checks performed by our operators indicate that the water is clear.”
23
24
25
26
27
28
19
TESTIMONY OF KATHERINE NUTTING (Cont.)
1
In addition, as described in GSWC’s response to ORA’s data request JA-010, Question
2
6 (a portion of which is included as Attachment 3), GSWC took the following actions in
3
response to the February 11, 2015 complaint:
4
5
“The customer notified us of discolored water in her home on the evening of February
6
11, 2015. GSWC immediately dispatched an operator to investigate. The operator did
7
not observe discolored water at the customer’s residence, nor in the water flushed from
8
a fire hydrant near the customer’s house. The customer indicated that the discolored
9
water cleared before we arrived at her residence. No other customers in this area
10
complained of discolored water on the date of the complaint. GSWC has checked the
11
water in the customer’s neighborhood daily for over one month following the February
12
11 report, and no discolored water has been observed.” The response to JA-010,
13
Question 6 was submitted to ORA on March 19, 2015, which demonstrates that the
14
water was checked daily for over one month to ensure that the discoloration did not
15
recur.”
16
17
(Q)
South Gramercy Place?
18
19
Do you have any other information pertaining to the water quality complaint at 14903
(A)
Following the investigation of the water quality complaint at 14903 South Gramercy
20
Place, the customer sent a video showing extremely discolored water coming out of her
21
bathroom tap and from her toilet tank to the City of Gardena, GSWC, and potentially
22
others. The video was also posted on YouTube. According to the operator’s report, the
23
discoloration of the water shown in the video was much more severe than what he
24
observed during his investigation. Though GSWC was aware of increased water quality
25
complaints related to discolored water in this portion of Gardena, the severity of the
26
27
28
20
TESTIMONY OF KATHERINE NUTTING (Cont.)
1
discoloration shown in Mrs. Morita’s video was atypical. Also, to our knowledge, no
2
other customer received water as severely discolored as what was shown on the video.
3
The operator who responded to Mrs. Morita’s complaint did witness some discoloration
4
in the water within her residence and that of the neighbor across the street; however, it
5
was in no way as severely discolored as the water shown in the video. Thus, GSWC
6
has described the complaint at 14903 Gramercy Place as an “isolated incident.” The
7
severely discolored water that the customer documented in her water was short-lived
8
and not typical of the water that GSWC customers were receiving.
9
Response and Investigation
10
11
(Q)
Place?
12
13
Did GSWC prepare a report pertaining to the complaint at 14903 South Gramercy
(A)
Yes. A report dated February 9, 2015 (Attachment 4) describing the incident and
14
GSWC’s investigation was submitted to DDW. The report described the investigative
15
measures as:
16

Reviewed complaint records to determine whether any other customer experienced
17
a similar occurrence. No other customers in this neighborhood contacted the
18
company complaining of discolored water on this date.
19

around the time of the complaint.
20
21

24
Reviewed main break records. No main breaks had occurred in this area around the
time of the complaint.
22
23
Reviewed flushing records. No recent hydrant flushing had occurred in this area

Reviewed main installation records. There were no tie-ins of new mains into the
system in this area around the time of the complaint.
25
26
27
28
21
TESTIMONY OF KATHERINE NUTTING (Cont.)

1
Traced the customer’s service line and reviewed as-built drawings to confirm the
2
main to which the customer’s service was connected. The investigation revealed that
3
the customer’s service line was tapped from a 4-inch cast iron pipe that was installed
4
in 1955.
5
6
The February 9 report concluded that “Golden State was unable to determine the cause
7
of the colored water incident at this customer’s residence. This was a temporary
8
occurrence and the water serving the customer is clear.”
9
10
(Q)
While GSWC was unable to identify the cause of the discolored water events at 14903
11
Gramercy Place with certainty, do you have an opinion as to possible causes of this
12
event?
13
(A)
Yes. It is true that GSWC did not determine the specific cause of the incident, meaning
14
that we did not discover a likely event that would have created a reverse flow or any
15
other mechanism that could disturb the material in the pipes. GSWC was able to
16
determine that the disturbance was localized, which is why the event was described as
17
“an isolated incident.”
18
19
Notwithstanding that no particular event was determined to be the cause of this water
20
quality complaint, the discolored water is attributable to sediment and debris that had
21
accumulated in older cast iron and steel mains in the distribution system. A large
22
component of this sediment is iron, which can appear black when it combines with sulfur
23
compounds in the distribution system under certain conditions. This assessment is
24
supported by a chemical analysis performed on a used filter provided by the customer.
25
26
27
28
22
TESTIMONY OF KATHERINE NUTTING (Cont.)
1
The analytical report (Attachment 5) states that a large component of the material found
2
on the filter is iron-based.
3
4
Moreover, the accumulation of these materials has been exacerbated by biofilm growth
5
which is supported by nutrients in the source waters. GSWC has limited those nutrients
6
and reduced chloramine demand through the measures and treatment projects
7
described in my testimony above. These measures have resulted in improvements to
8
the water quality issues in the Southwest System, however, have not solved all issues,
9
and accumulated debris remains a water quality issue. We continue to manage the
10
impacts created by past source water problems (i.e. legacy manganese accumulation)
11
through maintenance activities like UDF. We also continue to evaluate our groundwater
12
treatment plants for strategies to optimize the processes.
13
14
(Q)
residences at issue?
15
16
Has GSWC taken any actions to prevent another water discoloration event at the
(A)
Yes. As part of the complaint investigation, GSWC reviewed the as-built drawings at the
17
intersection of 149th Street and Gramercy Place. An operator traced the location of the
18
service line for 14903 Gramercy Place. It was determined that the service line was
19
tapped off of the water main near two 45-degree fittings and that the location of the
20
service line tap could increase the possibility of discolored water entering the
21
customer’s service. It was determined that relocating the customer’s service line so that
22
it was connected to the newer main on Gramercy Place could improve water quality at
23
this service. The service line was relocated from the water main on 149th Street to the
24
water main on Gramercy Place during the week of March 9, 2015.
25
26
27
28
23
TESTIMONY OF KATHERINE NUTTING (Cont.)
1
The service line serving the customer located at across the street from 14903 Gramercy
2
Place was tapped in a similar configuration as the service for 14903 Gramercy Place.
3
This customer has also experienced discolored water. It was determined that relocating
4
this service would be beneficial to water quality, and GSWC discussed this with the
5
customer on January 29, 2015. The service line serving this customer was relocated
6
from the water main on 149th Street to the water main on Gramercy Place during the
7
week of March 12, 2015.
8
In summary, the water quality complaint from 14903 South Gramercy Place is resolved.
9
10
11
Current Water Quality and Activities in the City of Gardena
12
Accelerated Flushing Activities
13
(Q)
complaint at 14903 Gramercy Place.
14
15
Describe in more detail the flushing activities that GSWC following the January 21, 2015
(A)
GSWC continued to implement UDF in WQA 5 following the complaint on Gramercy
16
Place in addition to expanding UDF to several other WQAs. Starting January 28, 2015,
17
GSWC deployed two separate UDF crews to flush two separate portions of the system
18
simultaneously. UDF was conducted from approximately 7:00 am to 10:00 pm until
19
February 18, 2015 when the UDF schedule was changed to 10:00 pm to 2:00 pm; two
20
separate crews flushing two separate areas were maintained. UDF was completed in
21
WQAs 2, 4, 5, as well as portions of 6 and 7, at which point the second UDF crew was
22
discontinued. The portion of the water system where UDF has been completed since
23
December 17, 2014 is shown in green on Attachment 6.
24
25
26
27
28
24
TESTIMONY OF KATHERINE NUTTING (Cont.)
1
The nominal water flow patterns in portions of WQAs 4, 5, 6, and 7 are complex,
2
necessitating a complicated order of UDF activities. GSWC decided to initially conduct
3
UDF in the Gramercy area against normal water flow because flushing with the normal
4
flow direction of water would require UDF of other large portions of the distribution
5
system first. GSWC’s plan was to complete UDF in this area twice, once against
6
normal water flow and once with normal water flow to ensure a successful outcome.
7
This plan was completed successfully and the outcome of UDF in this area was
8
satisfactory.
9
A timeline of WQAs flushed by UDF is provided below:
10
11
Area
12
Begin Date
End Date
November 6, 2014
February 6, 2015
13
WQA 2
14
WQA 4
February 6, 2015 February 21, 2015
15
WQA 5
December 17, 2015 February 25, 2015
16
Portion of WQA 6
February 16, 2015 February 20, 2015
17
WQA 6
February 25, 2015
18
Portion of WQA 7
February 2, 2015 February 26, 2015
19
Gramercy Area
January 30, 2015
20
Gramercy Area
March 18, 2015
February 2, 2015
February 23, 2015 February 25, 2015
21
22
23
Capital Improvements
(Q)
Describe any capital improvements that GSWC has undertaken as a result of its review
24
of the water quality issues in the portion of the City of Gardena where GSWC had
25
received increased water quality complaints.
26
27
28
25
TESTIMONY OF KATHERINE NUTTING (Cont.)
1
(A)
During the UDF process, operators came across a number of gate valves that were
2
either inadvertently closed or broken closed. GSWC has a valve exercising and
3
maintenance program that aims to exercise each valve in the system at least once
4
every five years. However, occasionally valves are broken during use in operations or
5
could be inadvertently left closed in between that time. When a broken valve was
6
encountered, operators would stop the UDF process, repair or replace the valve, and
7
continue the UDF process once the valve had been repaired or replaced. Water
8
Operations replaced 27 gate valves in the impacted area between January and May
9
2015; of these, 15 were found to be broken closed. Though this is a small number in
10
relation to the total number of valves that are present in the Southwest distribution
11
system, these valves could have a significant impact on water flow in the localized area
12
where they are located.
13
14
Closed gate valves can restrict water flow and lead to an increase in water age in the
15
distribution system. This can cause chloramine residual degradation and potentially
16
cause discolored water and/or odor. Replacement of the aforementioned gate valves
17
likely improved water flow in the areas where they are located thereby improving water
18
quality.
19
20
Additionally, as part of the investigation of the complaint on Gramercy Place, GSWC
21
came across a piece of 50 to 60 year-old 4-inch cast iron main on Gramercy Place
22
between 147th and 149th Streets that was creating a dead end and was not needed for
23
water service. This could contribute to high water age in that area and was thought to
24
be a potential contributor to the color and odor that customers had been experiencing in
25
26
27
28
26
TESTIMONY OF KATHERINE NUTTING (Cont.)
1
that area. This piece of pipe was disconnected from the system and abandoned in
2
March 2015.
3
Water Quality Monitoring
4
5
(Q)
in order to evaluate the current water quality conditions?
6
7
Has GSWC undertaken any additional water quality monitoring in the Southwest District
(A)
Yes. As required by the Total Coliform Rule, GSWC conducts bacteriological sampling
8
at our 43 dedicated sample stations throughout the Southwest system on a weekly
9
basis. Additionally, water samples from 21 of these sample stations are analyzed
10
weekly for turbidity, color, and odor. The sample results of weekly samples for January
11
2015 and February 2015 for the six sample stations located nearest to the Gramercy
12
area are provided in Attachment 7. No samples were present for total coliform or E. coli
13
during this time frame.
14
15
On February 4, 2015, a sample was collected from the front hose bib at the location the
16
complaint at 14903 South Gramercy Place. The sample was absent for total coliform
17
and E. coli. The lab report for this sample was provided to DDW and the complainant.
18
19
(Q)
Describe the water quality monitoring that has occurred in the Gramercy area of the City
20
of Gardena that GSWC has undertaken to confirm that its UDF activities have been
21
successful.
22
(A)
In the Gramercy area, water quality has been regularly monitored, and a detectable
23
chloramine residual has been routinely observed in the neighborhood. The monitoring
24
has also shown the water to be clear and free of odor. A table summarizing the total
25
26
27
28
27
TESTIMONY OF KATHERINE NUTTING (Cont.)
1
chlorine (also known as the combined chloramine) residual measurements and operator
2
observations of color and odor is provided below.
3
4
5
Date
Total Chlorine Residual
(mg/L)
Odor
Color
6
1/22/2015
0.21
None
None
7
2/12/2015
0.28
None
None
8
2/13/2015
0.17
None
None
9
2/15/2015
0.21
None
None
10
2/16/2015
0.43
None
None
11
2/17/2015
0.29
None
None
12
2/18/2015
0.21
None
None
13
2/19/2015
0.76
None
None
14
2/20/2015
0.75
None
None
15
2/21/2015
0.49
None
None
16
2/22/2015
0.47
None
None
2/23/2015
0.25
None
None
2/24/2015
0.25
None
None
2/25/2015
0.38
None
None
2/26/2015
0.29
None
None
2/28/2015
0.39
None
None
3/2/2015
0.68
None
None
3/3/2015
0.41
None
None
3/4/2015
0.67
None
None
3/6/2015
0.26
None
None
17
18
19
20
21
22
23
24
25
26
27
28
28
TESTIMONY OF KATHERINE NUTTING (Cont.)
1
Date
2
Total Chlorine Residual
(mg/L)
Odor
Color
3
3/7/2015
0.69
None
None
4
3/8/2015
0.42
None
None
5
3/9/2015
1.00
None
None
6
3/12/2015
0.55
Yes
Yes
7
(AM)
8
3/12/2015
0.77
None
None
9
(PM)
10
3/13/2015
0.44
None
None
11
3/15/2015
0.77
None
None
12
3/16/2015
0.23
None
None
13
3/17/2015
0.53
None
None
14
3/18/2015
0.24
None
None
15
16
(Q)
Describe the water quality monitoring that has occurred in the additional WQAs in and
17
around the City of Gardena that GSWC has undertaken to confirm that its UDF activities
18
have been successful.
19
(A)
Both during and after the UDF activities described above, GSWC performed additional
20
water quality monitoring in WQAs 2, 3, 4, 5, 6, and 7 to assess the effectiveness of UDF
21
as it was completed and maintain a comprehensive understanding of water quality in
22
these areas. During each monitoring event, water from approximately 80 fire hydrants
23
(discharged at a low flow rate) was measured for total chlorine residual, and
24
observations of color and odor were noted. A detectable residual was measured in all
25
but one of the approximately 240 separate measurements taken.
26
27
28
29
TESTIMONY OF KATHERINE NUTTING (Cont.)
1
2
Mild color and odor was observed in the water from a few of the fire hydrants, primarily
3
in WQAs 2 and 4. To address the residual color and/or odor in portions of WQA 2, the
4
area was converted from a chloramine disinfectant residual to a free chlorine residual
5
for a brief period of time (approximately four weeks). As noted earlier in this testimony,
6
free chlorine is a stronger disinfectant, so it was thought that brief exposure to free
7
chlorine could better oxidize the taste and odor causing constituents. This proved
8
successful, and no residual odor or color was observed after this activity. The cause of
9
the color and odor in WQA 4 was possibly due to the fact that some of water supply
10
comes from a portion of WQA 6, where water quality challenges still existed at the time.
11
As described in more detail below, given the success of the measures in WQA-2,
12
GSWC attempted to apply these same measures in WQAs 4, 5 and 6.
13
14
Additional water quality monitoring in WQAs 2, 3, 4, 5, 6, and 7 will continue to maintain
15
a comprehensive understanding of water quality in these areas and assist in developing
16
a more proactive and less reactive UDF schedule.
17
Continued Response
18
19
(Q)
the water quality in the impacted area of Gardena?
20
21
In addition to UDF, what is GSWC doing on an on-going basis to improve and maintain
(A)
Once UDF had been completed, lower than desired chloramine residuals were
22
observed in a few localized areas in a portion of the City of Gardena, as well as some
23
remnant odor and/or discoloration. It was determined that additional actions were
24
required to improve water quality in these areas.
25
26
27
28
30
TESTIMONY OF KATHERINE NUTTING (Cont.)
1
Since converting WQA 2 to a free chlorine residual was successful in stabilizing water
2
quality in that area, GSWC attempted to convert WQAs 4, 5 and 6 to a free chlorine
3
residual in May 2015. This involved converting the groundwater sources to free chlorine
4
and trying to maximize groundwater usage in the area. Converting the imported water
5
source connections to free chlorine would have been complicated and expensive, so
6
this was not attempted. Free chlorination of the wells took place for approximately two
7
weeks; however it proved difficult to maintain a free residual in the area since imported
8
chloraminated water was needed to serve the area at certain times of day. As a result,
9
little improvement was seen in the localized areas with remnant color and/or odor.
10
11
Also in May 2015, GSWC hired a contractor who is experienced in waterline
12
chlorination, to disinfect certain waterlines in the areas with remnant discolored water
13
and/or odor. This involved interrupting service to customers and applying a high dose
14
of free chlorine (up to 250 mg/L) to the lines for approximately four hours. This took
15
place during the weeks of May 18 and May 26, 2015. Unfortunately, this had little
16
impact on the areas where color and/or odor remained.
17
18
GSWC has also been exploring the use of swabbing or pigging to clean certain water
19
mains, as this has shown to be successful in improving water quality in other water
20
systems. This is a more aggressive means of cleaning water mains when UDF alone is
21
not effective. Pipe swabbing is a pipe cleaning technique that uses a soft bullet shaped
22
piece of foam, commonly referred to as a “ soft pig”, to clean water mains that are
23
relatively smooth and devoid of heavy tuberculation or scale. Swabbing with soft pigs is
24
typically used on cement lined metal, asbestos cement, or PVC pipes. The pig is
25
propelled by water pressure and mechanically scrapes accumulated sediment and
26
27
28
31
TESTIMONY OF KATHERINE NUTTING (Cont.)
1
materials including biofilm from the inside of the water main. Pipe pigging is a pipe
2
cleaning technique that is more aggressive than pipe swabbing and uses the same
3
general techniques. Pigging utilizes a series of progressively larger and harder pigs of
4
various materials to clean water mains. Pigging can remove sediments, biofilm,
5
accumulated precipitates, and heavy tuberculation from inside water mains.
6
7
Operations, Engineering, and Water Quality staff met with a company who provides this
8
service. The process involves interrupting services to customers, and there is a
9
significant amount of work that must be done in the field prior to the pigging, such as
10
tapping in locations were the pigs will enter and exit the pipe that is to be cleaned.
11
GSWC continues to evaluate pigging as an alternative to main replacement where
12
appropriate.
13
14
The activities that have been performed such as UDF, gate valve replacement, and
15
main chlorination have resulted in improved water quality in the Southwest system;
16
however, these measures did not address 100% of the water quality in the portion of the
17
City of Gardena where increased complaints had been occurring. As such, GSWC
18
persisted with identifying other actions that could sustain water quality in all portions of
19
the distribution system. This led us back to the local groundwater sources. Though all
20
sources are in full compliance with primary and secondary drinking water standards, we
21
considered whether there could be other, non-regulated constituents in the source water
22
that were contributing to chloramine degradation. Preliminary residual disinfectant
23
degradation testing showed that chloramine residual degraded quickly in the finished
24
water from some of the wells when held in clean bottles over a 48-hour period. This
25
showed that there appeared to be additional chloramine demand in the water produced
26
27
28
32
TESTIMONY OF KATHERINE NUTTING (Cont.)
1
by these wells when the water entered the distribution system. Based on this
2
information, GSWC removed the wells from service in early June 2015. This resulted in
3
immediate water quality improvement in the small areas in Gardena that were still
4
experiencing remnant color and/or odor. GSWC’s local groundwater sources are
5
currently being analyzed for potential treatment and evaluated for potential disinfection
6
process enhancements prior to being placed back in service
7
8
(Q)
increased water quality complaints in the Southwest System?
9
10
Has GSWC violated any drinking water standards at any time during this period of
(A)
No. GSWC has maintained and continues to maintain compliance with all primary and
11
secondary drinking water standards in the City of Gardena as well as the entirety of its
12
Southwest District. While GSWC recognizes and regrets that some customers received
13
water with discoloration and/or objectionable odor, the system was at no time in
14
violation of any drinking water standards.
15
16
Communications
17
Regulatory Communication
18
Throughout the event, GSWC communicated regularly with DDW. DDW is responsible
19
for monitoring public water systems’ compliance with State and Federal drinking water
20
standards. Upon request from DDW, GSWC provided records regarding water quality
21
complaints, flushing, water quality monitoring, and other operational records on several
22
different occasions during February 2015. GSWC also met with DDW staff on three
23
different occasions during February 2015. Though two of these visits were
24
unannounced, GSWC staff dedicated the time needed to provide DDW with updates on
25
our progress in addressing water quality concerns in the impacted area, and allowed
26
27
28
33
TESTIMONY OF KATHERINE NUTTING (Cont.)
1
them to review and copy additional operational records that they indicated were
2
necessary for their investigation. During one of these meetings (2/13/15), DDW staff
3
spent time in the field observing flushing crews and learning about how UDF plans are
4
executed. GSWC also met with representatives from DDW (local and regional), the
5
United States Environmental Protection Agency, the California Public Utilities
6
Commission’s Office of Ratepayer Advocates, and the Los Angeles County Department
7
of Environmental Health on February 19, 2015. During this meeting, GSWC provided
8
an update on our progress with addressing the water quality issues in Gardena and
9
responded to questions from the other meeting participants.
10
11
Additionally, GSWC initiated communications with the Commission’s Division of Water
12
and Audits (DWA) and kept them informed on the status of the Southwest event.
13
GSWC provided DWA with copies of DDW communications and replies to data requests
14
from DDW. GSWC responded to several data requests from DWA on this matter,
15
regarding population, customer class and demographics in the City of Gardena. DWA
16
was provided with a copy of the letter that was provided to customers, civic leaders, and
17
elected state officials in the City of Gardena that addressed the Southwest event and a
18
copy of the door hanger utilized to notify impacted customers.
19
Customer and Community Communications
20
21
(Q)
other stakeholders while resolving the water quality issues.
22
23
24
Describe the various methods GSWC used to communicate with its customers and
(A)
GSWC communicated with its customers in multiple ways, as described below.
Written Statements
25
26
27
28
34
TESTIMONY OF KATHERINE NUTTING (Cont.)
1
GSWC issued a written statement regarding water quality reports in Gardena on
2
January 27, 2015 with updated statements on January 28 and January 29, 2015
3
(Attachment 8). Updated statements regarding water quality in the City of Gardena and
4
our efforts to address water quality complaints was posted to our website on February
5
5, March 20, April 24, April 30, and June 1, 2015 (Attachment 9).
6
7
Flushing Notification
8
GSWC began placing door hangers on the premises of customers in the immediate
9
vicinity of UDF activities on February 5, 2015. This was done as a courtesy to our
10
customers; it is not required by regulation. An example of the door hanger is provided
11
as Attachment 10. Postcards were developed and mailed to customers in advance of
12
planned flushing activities. The first set of postcards was mailed on Monday, February
13
9, 2015. Door hangers were placed until our customers received the postcards on
14
approximately Wednesday February 11, 2015.
15
16
On February 20, 2015 GSWC launched a webpage on our website dedicated to flushing
17
in the Southwest District (www.gswater.com/flushing-southwest). The schedule on the
18
webpage is updated daily with the general location of flushing activities for that day.
19
Flushing postcards are mailed prior to beginning UDF in a specific geographic area.
20
The flushing postcards include the URL of the flushing webpage. An example of the
21
flushing postcard and the webpage are included in Attachment 11.
22
23
Community Meetings
24
25
26
27
28
35
TESTIMONY OF KATHERINE NUTTING (Cont.)
1
On February 12, 2015 GSWC held a community meeting in Gardena, California. The
2
meeting included a 20 minute presentation (Attachment 12) and an hour and a half long
3
question and answer session. The meeting was attended by 250 – 300 people.
4
5
GSWC made a presentation at a meeting held by the Gardena’s Environmental Justice
6
Committee on March 19, 2015. There were approximately 75 – 100 people in
7
attendance. Several customers asked questions, but the general consensus from the
8
group was that water quality had improved.
9
10
GSWC made a presentation on the drought, along with a water quality update, to the
11
Holly Park Homeowners Association in Gardena on April 2, 2015. No customers asked
12
questions or expressed concern about water quality during that meeting.
13
14
Other Meetings
15
The Vice President of Water Operations and the General Manager for the Southwest
16
District met with the Mayor of Gardena and the City Manager on February 25, 2015.
17
The Mayor filed an Informal Complaint with California Public Utilities Commission on
18
behalf of the City of Gardena. The complaint asserted that the City had received many
19
water quality complaints from its residents over the past three years, and that the
20
number of complaints had intensified in the past six months. During the meeting, GSWC
21
addressed the Mayor’s concerns and described the actions we had taken to address the
22
water quality issues. GSWC also expressed regret that many of our customers in
23
Gardena were not satisfied with our service, and that the City felt they had to get
24
involved as a result. The Mayor offered several helpful suggestions regarding
25
community engagement, and he suggested that we meet with each of the Gardena
26
27
28
36
TESTIMONY OF KATHERINE NUTTING (Cont.)
1
Council members individually. GSWC tried several times to schedule meetings with the
2
other Councilmembers, but received no response.
3
4
The Vice President of Water Operations and the General Manager for the Southwest
5
District met with Los Angeles County Supervisor Mark Ridley-Thomas on June 11,
6
2015. The Supervisor was given an update on water quality in Gardena and assured
7
that the water quality in the previously impacted portion of Gardena was currently good.
8
The meeting was positive, and the Supervisor appeared satisfied with our response. He
9
encouraged us to continue to engage the Gardena community in an effort to rebuild our
10
relationship with the customers who were dissatisfied with our water service.
11
12
The Senior Vice President of Regulated Utilities met with California Assemblymember
13
David Hadley and California Senator Isadore Hall, III on February 19, 2015. She met
14
with Assemblymember Autumn Burke on May 5, 2015; Assemblymember Hadley also
15
joined that meeting. She also held a follow-up meeting with Senator Hall on May 5,
16
2015.
17
18
Written Correspondence
19
GSWC mailed a letter regarding water quality dated February 5, 2015 to all our
20
customers located in the City of Gardena. At the same time, a letter was mailed to local
21
stakeholders, including the Gardena City Council, City Manager, and Police Chief, as
22
well as the State Assembly members and Senator that represent Gardena. Examples of
23
both letters are included in Attachment 13.
24
25
26
27
28
37
TESTIMONY OF KATHERINE NUTTING (Cont.)
1
A letter dated May 29, 2015 was mailed to approximately 1,000 Gardena customers on
2
June 3, 2015. The letter was sent to customers who had called us with a water quality
3
concern since July 1, 2014, attended our community meeting on February 12 (and
4
signed in), and/or participated in an informal water quality survey that was conducted by
5
one of our customers and provided to us. A copy of the letter is provided in Attachment
6
14. At the same time, an update was mailed to the stakeholders listed above, as well
7
as the Los Angeles County Supervisor and US Congresswoman that represent
8
Gardena and several other elected officials that have expressed interest in the situation.
9
A copy of this letter is provided in Attachment 15.
10
11
Media Engagement
12
Several GSWC representatives have engaged in interviews with members of the media,
13
including television, radio and print. Most of the media response occurred in late
14
January and on February 12, 2015, following our community meeting. In all interviews,
15
GSWC encouraged our customers to call us with any concerns and committed to
16
following up with every customer who contacted us.
17
18
GSWC believes that the media’s attempts to sensationalize a discolored water event
19
experienced by one of our customers did not accurately portray the typical quality of
20
water in the Gardena system, nor did it aid in GSWC’s ability to effectively respond to
21
our customers’ concerns. A portion of the Southwest system did experience some
22
discoloration, which is not uncommon in systems with similar pipeline age and
23
materials. Unfortunately, a single video caused a drastic response; if the water quality in
24
Gardena was actually what was depicted in the video, we would have been flooded with
25
hundreds of calls. This was not the case; the water depicted in the video is not
26
27
28
38
TESTIMONY OF KATHERINE NUTTING (Cont.)
1
indicative of the water being generally served to customers, now or at any time in the
2
past.
3
Future Work
4
5
(Q)
Has GSWC identified any additional actions that it recommends should be taken in the
6
City of Gardena and/or the Southwest District to reduce the likelihood of a recurrence of
7
the water quality issues that have recently taken place?
8
(A)
Yes. At this date, the Southwest system has stabilized. As shown in the table below,
there are fewer customer complaints, and routine monitoring indicates that total chlorine
9
10
residuals are in accordance with industry norms. Our efforts now are directed at
11
evaluating source water treatment and distribution system maintenance techniques to
12
look for additional opportunities to optimize the system and thereby prevent the risk of
13
any recurrence of discolored water or other aesthetic issues experienced by our
14
customers.
15
16
Area
Jan-15 Feb-15 Mar-15 Apr-15 May-15 Jun-15
17
Southwest system
40
50
20
24
26
15
18
City of Gardena
33
46
14
17
21
12*
19
*11 of 12 prior to 6/5/15. Wells removed from service 6/2/15.
20
21
(Q)
Describe the actions GSWC is taking to investigate and address source water quality.
22
(A)
GSWC is conducting additional evaluations of each of our groundwater sources to
23
assess the stability of the finished water entering the distribution system and the effects
24
of this water on distribution system water quality. This includes evaluating the amount
25
of available nutrients such as ammonia, total organic carbon, and phosphates available
26
27
28
39
TESTIMONY OF KATHERINE NUTTING (Cont.)
1
for microorganism growth. As mentioned previously, GSWC is phasing out the use of
2
SeaQuestTM, which contains phosphates.
3
4
These evaluations will also focus on the systems and process controls previously
5
implemented and identify opportunities for further optimization and/or treatment.
6
Additionally, the processes of combining naturally-occurring ammonia with chlorine to
7
form chloramines will be evaluated to determine if the finished water is of sufficient
8
chemical and biological stability. Based on the findings of these evaluations it may be
9
advisable to remove naturally-occurring ammonia prior to the formation of a chloramine
disinfectant residual.
10
11
12
(Q)
Please summarize the testimony above.
13
(A)
The testimony discussed how GSWC has been focused on optimizing water quality in
14
the Southwest system for many years and will continue to do so moving forward. GSWC
15
has implemented many improvements in the Southwest system, both at the sources
16
and within the distribution system, over the past 20 years, with the express intent of
17
optimizing water quality. The testimony stressed that the water served in the Southwest
18
system did and does comply with all drinking water standards and that GSWC places
19
utmost importance on compliance. It described the actions GSWC has taken to address
20
recent water quality concerns raised by some residents of the City of Gardena, including
21
GSWC’s efforts to communicate to and solicit feedback from our customers and the
22
community as a whole. Finally, it discussed GSWC’s planned actions moving forward to
23
ensure continued compliance and provide optimal water quality for our customers.
24
25
26
27
28
40
TESTIMONY OF KATHERINE NUTTING (Cont.)
1
In conclusion, GSWC experienced aesthetic water quality issues in a portion of the City
2
of Gardena in the latter part of 2014 through early 2015. These issues have been
3
addressed, and the quality of the water in that area and throughout the Southwest
4
system is good. GSWC is committed to maintaining compliance with drinking water
5
standards and will continue to do everything we can to provide the best quality of
6
service to our customers.
7
8
(Q)
Does this conclude your testimony?
9
(A)
Yes, it does.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
41
Attachments
1. 1996 and 2007 WQ reports
2. Response to ORA Data Request JA-009
3. Response to ORA Data Request JA-010 (partial)
4. Report to DDW dated 2/9/15
5. Morita filter analytical report
6. Map Showing Areas of UDF
7. Sample Results Tables for Jan Feb 2015 6 sample locations
8. GSWC written statements 1/27, 28, 29, and 30/15
9. GSWC updated statements to website February 5, March 20, April 24, April 30, and
June 1, 2015
10. Example UDF door hanger
11. Example of Flushing post card and webpage
12. Gardena Townhall meeting Presentation PDF – 2/12/15
13. Letter to Customers and Stakeholders Regarding WQ 1/30/15
14. Letter to 1,000 Gardena customers dated 6/3/15
15. WQ update letter to stakeholders dated 6/1/15
16. Example of UDF Plan
Schedule 1
QUALIFICATIONS OF
KATHERINE NUTTING
My name is Katherine S. Nutting and my business address is 1600 W. Redondo
Beach Blvd., Suite 101, Gardena, CA 90247. I joined the Company in May 2006.
I graduated from the University of Massachusetts, Amherst in May of 1995 with a
Bachelor of Science degree in Environmental Sciences. I also hold a Master’s degree in
Environmental Science & Engineering from the University of North Carolina, Chapel Hill. I
am certified as a T2 Water Treatment Operator and D2 Water Distribution Operation by the
California State Water Resources Control Board. Prior to joining GSWC, I was a Water
Quality Project Manager for California Water Service Company.
In May of 2006, I joined GSWC as the Central District Water Quality Engineer. In
February of 2008 I was promoted to Water Quality Manager. In February 2015 I was
appointed as the General Manager for GSWC’s Southwest District. I had been filling this
role on an interim basis since June of 2014. I also filled interim roles of Central District
Manager (February 2011 to February 2012) and CC&B Program Manager (February to
September 2012).
As the Water Quality Manager, my duties included implementation of Company
water quality policies, review and evaluation of the impact to the Company of proposed
water quality and environmental regulations and emerging issues and oversight of three to
four district Water Quality Engineers in developing comprehensive plans to meet all
regulatory requirements.
Schedule 1
As the Southwest District General Manager, my duties include overseeing the daily
operations and maintenance of the District. This includes, providing operational input to
annual business plans, preparing and controlling the district budgets for responsible areas,
and ensuring that operational and financial targets are met or exceeded. I am also
accountable and responsible for ensuring that operational integrity is maintained, including
regulatory compliance in all facilities, to include, operating and maintaining the district
operations in compliance with the appropriate environmental, health, and safety
regulations.
Application No. A.14-07-006
Exhibit No. GS-165
Date: July 24, 2015
Witness: Katherine Nutting
BEFORE THE
PUBLIC UTILITIES COMMISSION
OF THE STATE OF CALIFORNIA
GOLDEN STATE WATER COMPANY
PHASE II - WATER QUALITY
ISSUES IN THE CITY OF GARDENA
TESTIMONY
KATHERINE NUTTING
Attachments – Volume 1
Attachment 1
Prepared by:
GOLDEN STATE WATER COMPANY
630 East Foothill Boulevard
P. O. Box 9016
San Dimas, CA 91773-9016
July 2015
GOLDEN STATE WATER COMPANY
A.14-07-006
PREPARED TESTIMONY
KATHERINE NUTTING
(Exhibit GS-165)
ATTACHMENT 1
1996 and 2007 CH2MHill Reports
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Golden State
Water
Company
A Subsidiary of American States Water Company
II
region
Southwest
System
WATER
QUALITY
STUDY
PREPARED BY
WB062006009SAC
JULY 2007
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Aerial photograph on front cover courtesy of Google™ Earth 2007© and DigitalGlobe 2007©.
Image modified by CH2M HILL.
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Final Report
Southwest System
Water Quality Study
Prepared for
Golden State Water Company
July 2007
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II
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SOUTHWEST WATER QUALITY REPORT.DOC
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Contents
Section
Page
Southwest System Water Quality Study: Executive Summary............................................1
Introduction.......................................................................................................................1
Existing Distribution System Facilities..........................................................................2
Hydraulic Model Update ................................................................................................2
Disinfectant and Disinfectant By-Product Evaluation ................................................3
Source Water Evaluation .................................................................................................6
Water Quality Issues/Concerns and Water
Source Treatment Requirements .......................................................................6
Treatment System Automation .......................................................................10
Distribution System Disinfectant Residual....................................................13
System Operation and Improvement Assessment ....................................................13
Estimated Costs .................................................................................................15
Findings and Recommendations..................................................................................16
Phase 1 Recommendations...............................................................................18
Phase 2 Recommendations...............................................................................18
Tables:
ES-1
ES-2
ES-3
ES-4
ES-5
Calculated First-Order Reaction Coefficients for Selected Southwest District Water
Samples
Groundwater Well Water Quality Issues/Concerns
Southwest Plant Existing Level of Treatment and Treatment Needs
Hydrogen Sulfide Treatment Technology Benefits and Drawbacks
Estimated Construction Costs for Automated Disinfection Facilities
Figures:
ES-1
ES-2
ES-3
No Treatment or Reservoir Facility Configuration
Treatment with Reservoir Facility Configuration
Treatment without Reservoir Facility Configuration
Appendices:
A
B
C
D
E
F
Southwest System Model Condition TM
Hydraulic Model Development and Steady State Calibration Results–Southwest
System
Simulated Distribution System Testing for the Southwest System
Southwest System – Source Water Evaluation
Southwest System Water Quality Study: System Operation and Improvement
Assessment
Southwest System Operations Analysis: MWD Supplies Only
SOUTHWEST WATER QUALITY REPORT.DOC
III
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IV
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Southwest System Water Quality Study:
Executive Summary
Introduction
The Golden State Water Company (GSWC) owns and operates the Southwest System which
produces and distributes water to a portion of the City of Los Angeles. The Southwest
System provides potable water through approximately 50,000 connections to the cities of
Gardena and Lawndale, a portion of the cities of Carson, Compton, El Segundo, Hawthorne
and Inglewood, and unincorporated portions of Los Angeles County, such as Lenox,
Athens, and Del Aire.
Water quality problems have persisted in the Southwest System for over ten years. In 1996,
GSWC detected nitrification episodes and implemented system improvements to mitigate
the problems. Based on an evaluation by McGuire Environmental Consultants and
CH2M HILL, GSWC converted the Southwest System disinfection to chloramines in an
effort to maintain an adequate disinfectant residual in the distribution system to control
nitrification. Following the conversion to chloramines, regular flushing was also
implemented in the distribution system to help prevent nitrification. Despite these attempts
to improve water quality, positive bacterial samples have occasionally been collected within
the distribution system, starting in August 2003. These results indicate that low disinfectant
residuals are still a problem in the Southwest System.
GSWC initiated a water quality study for the Southwest System to evaluate what causes
were leading to the positive bacterial tests and to develop recommended improvements to
mitigate the problems. As part of this study, Simulated Distribution System (SDS) testing
was conducted on selected water supply sources. The SDS tests analyzed the effectiveness of
chlorine and chloramines as disinfectants, and an evaluation was conducted to assess the
source water quality and treatment provided at each groundwater well. To analyze how the
water quality changed within the distribution system, a computer model was used. GSWC
provided an existing hydraulic computer model of the Southwest System for this study.
This model was evaluated for completeness, updated to include recent improvements, and
calibrated for both steady state and extended period simulation (EPS) conditions. The
hydraulic computer model was then applied to evaluate the system operation and source
blending with the information provided from the SDS testing and source water quality
evaluation. Based on the results of the system operation analysis from the hydraulic model,
system improvements were evaluated and recommendations were developed. This
executive summary provides an overview of the study tasks and summarizes the findings
and recommendations presented in the Technical Memorandum (TM) prepared for each
task. The study TMs are attached to this document as appendices.
SOUTHWEST WATER QUALITY REPORT.DOC
1
SOUTHWEST SYSTEM WATER QUALITY STUDY
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Existing Distribution System Facilities
The Southwest System consists of three pressure zones, with approximately 430 miles of
pipe that ranges in size from 2-inches to 20-inches. There are five ground storage tank and
pump station sites, 15 groundwater wells, and seven reservoirs at well sites. Imported water
is purchased from the Metropolitan Water District of Southern California (Metropolitan).
The Southwest System receives Metropolitan supplies through 12 connections with the West
Basin Municipal Water District (WBMWD) and the Central Basin Municipal Water District
(CBMWD). WBMWD and CBMWD are wholesale agencies for Metropolitan.
Hydraulic Model Update
GSWC provided an existing hydraulic computer model of the Southwest System to analyze
the water quality issues within the distribution system. Based on an evaluation of the
existing model (see Appendix A), it was recommended that the existing H2ONET computer
model be upgraded and converted for use in the modeling software H2OMAP. GSWC’s
existing Southwest System water distribution system model was then updated to reflect
2006 operating conditions and calibrated to field conditions (see Appendix B).
Using an AutoCAD file that GSWC provided of the water distribution system, the network
was visually evaluated for pipe connectivity and pipe attributes. The H2OMAP model was
updated to incorporate pipes that had been installed in the field since the last update to the
model. This update involved adding some new pipes and changing some diameters in the
model. The model was also modified to update the operating information, such as pump
curves and tank geometry, for pumping and storage facilities. Water system demands were
updated and distributed within the model using geocoded billing records.
A Calibration Plan was developed and implemented to field test the distribution system and
verify the accuracy of results from the computer model. Twelve hydrant flow tests were
conducted across the Southwest System. The results from the computer model were
compared to the field observations. The comparisons were categorized as High, Medium, or
Low to indicate the level of confidence in the model results. The static calibration results
yielded a Medium confidence while the dynamic results (with the hydrants flowing)
produced a High level of confidence. It was noted that the tests in the southwestern portion
of the system showed the greatest difference between the model-predicted results and the
field observations.
For the EPS calibration, Supervisory Control and Data Acquisition (SCADA) data was
collected for the Southwest System facilities. Controls settings were entered in the model to
turn pumps on or off as appropriate. Flow and pressure controls were entered for the
Metropolitan connections. Tank levels were also entered into the model. The hydraulic
model was run for a week long simulation period to evaluate how the model simulated the
system operation. Tank levels and Metropolitan flows were compared to SCADA for the
week long period. The tank level variation predicted by the model compared well with the
data collected from SCADA. In some instances, it was apparent that not all of the level
variation data for tanks was recorded by SCADA, so some assumptions were made on the
level variation trends. Since the pump stations and ground storage tanks are operated on a
clock-time basis and fill over a defined period of time each evening and the pumps are
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operated over a defined period of time each morning to assist with meeting peak hour
demands, the assumption for the level variation for the storage tanks was considered
acceptable.
In comparing the SCADA reported flow from the Metropolitan connections and the model
predicted flow from each of the connections, the trends for increases and variation in flow
was duplicated by the model, but not all of the peaks were duplicated. It was believed that
this was the result of using a smoothed diurnal demand curve that may not have captured
the instantaneous flow peaks. Since the goal of this study was to evaluate general water
quality trends and not necessarily evaluate system hydraulics, this level of EPS calibration
was considered to be acceptable.
Disinfectant and Disinfectant By-Product Evaluation
As part of the water quality study, a disinfectant and disinfectant by-product evaluation
was completed. This evaluation was conducted for the following four main reasons:
1. Compare the relative effectiveness of chlorine and chloramines for maintaining
adequate residual disinfectant levels in the Southwest System.
2. Compare disinfection by-product formation potential for selected Southwest System
water sources using both chlorine and chloramines.
3. Evaluate the effectiveness of SeaQuest, a commercial brand of corrosion inhibitor, for
reducing the corrosion rate of cast iron pipe in the Southwest System.
4. Obtain chlorine and chloramine reaction coefficients for selected water supply sources
that can be used in the future to model and predict water quality dynamics in the
Southwest System.
Representative source water samples from three groundwater wells (Dalton, Yukon, and
Southern) and from the Jensen Plant were collected from the Southwest System on
August 17, 2005 for analysis. Metal pipe coupons were also collected on this day. These
samples were used to conduct the Simulated Distribution System (SDS) testing. For this
study, three separate sets of SDS tests were conducted using the source water samples and
metal coupons provided by GSWC:
1. Baseline Experiments. The “Baseline” experimental setup was formulated with the
intent of collecting information on bulk decay coefficients for chlorine and chloramine
disinfectants, along with disinfection by-product (DBP) formation potentials for each of
the four water samples selected for study.
2. Metal Coupon Experiments. The “Metal Coupon” experimental setup was formulated
with the intent of collecting information on wall reaction coefficients for chlorine and
chloramine disinfectants, along with DBP formation potentials for each of the four water
samples selected for study.
3. Sequestration Experiments. The “Sequestration” experimental setup was designed to
provide information on wall reaction coefficients for chlorine and chloramine in the
presence of SeaQuest, a sequestration agent that is being used in the Southwest System
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to control the corrosion of metal pipe in the distribution system. SeaQuest allows the
gradual removal of pre-existing corrosion, scale, and bio-film buildup, while inhibiting
further pipe degradation.
The following observations were made from the results of the SDS testing:
•
For a given water sample, chloramine disinfection maintains a higher disinfectant
residual concentration than chlorine during the 4-day duration of the SDS experiments.
•
Individual water samples exhibit significant differences in chlorine disinfection residuals
during the 4-day duration of the SDS experiments; whereas, only minor differences were
noted for chloramine residuals between the water samples.
•
For a given water sample, the Metal Coupon experiments have lower chlorine and
chloramine residual concentrations than the “Baseline” experiments.
These results were expected, and the SDS testing produced quantifiable bulk and pipe wall
decay rates for each of the groundwater sources and water supplied from Metropolitan’s
Jensen Water Treatment Plant.
The results from the DBP formation potential tests lead to the following observations:
•
Disinfection by-product formation potential exhibits a direct relationship to the amount
of natural organic matter that is present in the water supply.
•
For a given water sample, chlorine generates a greater amount of disinfection
by-products than chloramine.
•
There are no significant difference between the “Metal Coupon” experiments and the
“Baseline” experiments in terms of disinfection by-product formation potential.
•
Exceedance of the 80-ppb MCL for TTHMs is likely if chlorine is used as the disinfectant
for water from the Yukon Well No. 4 and imported water from Metropolitan’s Jensen
Water Treatment Plant.
Corrosion inhibition tests were also conducted to evaluate the capacity of SeaQuest to
reduce the corrosion of the metal pipes by coating the interior surface of the pipes to
minimize any reducing reaction with the disinfectant. The SDS tests that applied SeaQuest
showed that the residual disinfectant concentration was higher than without SeaQuest,
demonstrating that the SeaQuest chemical addition is performing as expected. However, the
benefit provided by using SeaQuest to maintain a higher disinfection residual was only a
minor benefit, and there was no benefit provided in the reduction of DBP concentrations
through sequestering of the natural organic matter in the distribution system.
From the results of the SDS testing, reaction coefficients for both bulk decay and wall decay
were generated for each water source. These coefficients are summarized in Table ES-1.
These coefficients are generally lower (showing less decay and higher chlorine residual) but
are still in good agreement with published values reported in a previous study conducted
by CH2M HILL in 1996 for GSWC. The published kb values for chlorine from the previous
study range between 0.14/day (d) and 17.7/d; whereas, the experimental values reported in
this study range between 0.04/d and 0.63/d. The same is true for the chlorine wall decay
coefficients and the chloramine bulk decay coefficients. Published kw values for chlorine
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from the previous study range between 1.15/d and 16.1/d; whereas, the experimental
values reported in this study range between 0.11/d and 0.85/d; and the published
chloramine kb values range between 0.04/d and 0.89/d while the experimental values from
this report range between 0.06/d and 0.09/d.
TABLE ES-1
Calculated First-Order Reaction Coefficients for Selected Southwest District Water Samples
Water Sample
Reaction Coefficient (1/d)
Bulk Decay, kb
Overall Decay, k
Overall Decay w/
SeaQuest, k
1
Wall Decay , kw
Wall Decay with
2
SeaQuest , kw
1
2
Dalton No. 1
Yukon No. 4
Southern No. 5
Jensen Plant
Chlorine
0.126
0.634
0.0442
0.617
Chloramine
0.0869
0.0862
0.0605
0.0811
Chlorine
0.235
1.483
0.197
0.799
Chloramine
0.283
0.209
0.189
0.192
Chlorine
0.165
0.720
0.164
0.864
Chloramine
0.170
0.169
0.159
0.148
Chlorine
0.109
0.849
0.153
0.182
Chloramine
0.196
0.123
0.129
0.111
Chlorine
0.0390
0.0860
0.120
0.247
Chloramine
0.0831
0.0828
0.0985
0.0669
Wall Decay (kw) = Overall Decay (k) - Bulk Decay (kb)
Wall Decay with SeaQuest (kw) = Overall Decay with SeaQuest (k) - Bulk Decay (kb)
The reaction coefficients shown in Table ES-1 were used to predict water quality in the
Southwest System water distribution system as described in the Simulated Distribution
System Testing for the Southwest System TM, which is included as Appendix C.
In reviewing the decay coefficients provided in Table ES-1, the decay coefficients do not take
into account any demand that is exerted on the chlorine dose by other inorganics such as
iron, manganese, or hydrogen sulfide that may be present in the groundwater supplies. The
decay coefficients are representative of the demand that is placed on the disinfectant after
the initial raw water inorganic contaminant demands have been exerted.
The following observations developed from the results of the SDS and DBP formation
potential testing:
• Chloramine is the preferred choice over chlorine for maintaining adequate disinfectant
residuals in the Southwest System. When using chloramine, periodic shock chlorination
of the system may be required in order to control biogrowth associated with the growth
of coliform and nitrifying bacteria. Effective use of shock chlorination may require
installation of rechlorination stations at strategic locations in order to ensure that all
areas within the distribution system are treated.
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• Chloramine is preferred over the use of chlorine to minimize the formation of
disinfection by-products in the Southwest System.
• The addition of SeaQuest to the Southwest System water supplies provides little or no
benefit in terms of maintaining chloramine residuals of at least 0.5 mg/L in the
distribution system. However, if chlorine is used as the disinfectant, the experimental
results suggest that SeaQuest corrosion inhibitor will provide a significant benefit in
terms of maintaining chlorine residuals of at least 0.5 mg/L for a 2-day residence time in
the distribution system.
•
The results of SDS testing provide quantitative information that can be applied in the
future by GSWC staff to perform water quality modeling of the Southwest System.
Source Water Evaluation
The study also included an evaluation of the treatment requirements for the Southwest
System water supply sources, which include local groundwater and imported water. In
addition to identifying source water treatment needs, this evaluation also looked at the
extent of existing disinfection process automation and provided upgrade recommendations.
The specific goals of the source water evaluation study were to:
• Review the quality of the groundwater being produced by each of the active GSWC
wells against the current level of treatment to determine if supplemental treatment
is required to remain in compliance with current and future drinking water
regulations.
• Assess the current level of automation provided for the treatment and disinfection
systems at each of the well sites to identify improvements necessary to provide a
sufficient dose rate of the disinfectant such that an adequate residual will be
maintained throughout the entire distribution system.
The Source Water Evaluation TM (see Appendix D) provides the results of the source water
evaluation.
Water Quality Issues/Concerns and Water Source Treatment Requirements
The primary water quality concerns with the groundwater sources to the Southwest System
are hydrogen sulfide, iron, manganese, and methane. A summary of the specific
groundwater quality concerns for each well in the Southwest system is presented in
Table ES-2. Methane is present in the Truro Plant groundwater. GSWC has taken the Truro
Plant well permanently out of service since there is too great of a health and safety risk to
continue to use that water source. The Belhaven No. 4 well is a new well that has not been
placed into operation; thus, the water quality issues that may be associated with that well
are not known at this time. The water provided by Metropolitan is treated to drinking water
standards prior to delivery to the Southwest System. The water delivered by Metropolitan
to the Southwest System is disinfected with chloramine and has a total combined chlorine
residual of 2.5 mg/L.
Several of the groundwater sources have naturally occurring ammonia. Since
chloramination is the standard disinfection practice for the Southwest System, that type of
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disinfection along with the naturally occurring ammonia in the groundwater raises another
water quality concern: excess ammonia being delivered to the distribution system. The
incomplete consumption of ammonia by chlorine addition in the chloramination process can
result in increased biogrowth and lower disinfectant residuals in the distribution system
and exacerbate the nitrification problem.
TABLE ES-2
Groundwater Well Water Quality Issues/Concerns
Well
th
Water Quality Issue/Concern
129 St. Well No. 2
None
Ballona Well No. 4
None
Ballona Well No. 5
None
Belhaven Well No. 3
None
Belhaven Well No. 4
None
Compton-Doty Well
None
Dalton Well No. 1
None
Doty Well No. 1
Hydrogen Sulfide, Iron & Manganese
Doty Well No. 2
Hydrogen Sulfide, Iron & Manganese
Goldmedal Well No. 1
Manganese
Southern Well No. 5
Manganese
Southern Well No. 6
Manganese
Truro Well No. 4
Hydrogen Sulfide, Methane &
Manganese
Yukon Well No. 4
Hydrogen Sulfide
Yukon Well No. 5
Hydrogen Sulfide
Based on the source water quality assessment, the only water source that has water quality
issues/concerns is the groundwater source. Table ES-3 summarizes the level of existing
treatment being provided at each of the plant sites with groundwater production, along
with the supplemental treatment needs based on the water quality issues/concerns
identified in Table ES-2.
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TABLE ES-3
Southwest Plant Existing Level of Treatment and Treatment Needs
Well
th
Treatment
Needs
Existing Treatment
129 St. Plant
Chloramination & Corrosion
Control
None
Ballona Plant
Chloramination & Corrosion
Control
None
Belhaven Plant
Chloramination
Corrosion Control
Compton-Doty Well
Chloramination
Corrosion Control
Dalton Plant
Chloramination & Corrosion
Control
None
Doty Plant
H2S Aeration, Chloramination &
Corrosion Control
Iron & Manganese Treatment
Needed for Both Wells
Goldmedal Plant
Manganese Filtration,
Chloramination & Corrosion
Control
None
Southern Plant
Chloramination & Corrosion
Control
Manganese Treatment for
Well No. 5 is Under
Construction. Iron &
Manganese Treatment may
be needed for Well No. 6,
based on recent water quality
data
Truro Plant
Manganese Filtration, H2S
Aeration, Chloramination &
Corrosion Control
None. Groundwater source is
permanently out of service
Yukon Plant
Chlorination for H2S Removal &
Corrosion Control
H2S
Based on the groundwater quality information provided by GSWC and the information
summarized in Table ES-3, the existing treatment provided at the 129th Street Plant, Ballona
Plant, Dalton Plant and the Goldmedal Plant is adequate to address the water quality
issues/concerns for those water sources and additional treatment is not needed. No
additional treatment is required at the Truro Plant since the groundwater source has been
permanently taken out of service due to health and safety concerns associated with the
methane present in the well groundwater However, that is not the case for the Belhaven
Plant, Compton-Doty Plant, Doty Plant, Southern Plant, and Yukon Plant. Corrosion control
chemical addition needs to be provided at the Belhaven Plant and Compton-Doty Plant
through the installation of SeaQuest chemical storage and feed facilities. Iron and
manganese treatment needs to be provided for both wells at the Doty Plant. GSWC has
designed an iron and manganese treatment system for the Doty Plant, which is scheduled to
be constructed in Fiscal Year (FY) 2006. A manganese treatment system is being constructed
for Southern Well No. 5 in FY 2006. Southern Well No. 6 also has manganese concentrations
that are above the drinking water SMCL for that contaminant, and a manganese treatment
system may need to be designed and constructed for that well. The breakpoint chlorination
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treatment for hydrogen sulfide control at the Yukon Plant is producing total trihalomethane
(TTHM) concentrations that exceed the Stage 2 DBP Rule MCL of 80 μg/L. A different
hydrogen sulfide strategy is needed at the Yukon Plant site for future compliance with the
Stage 2 DBP Rule. Table ES-4 summarizes the available hydrogen sulfide treatment
technologies that can be employed at the Yukon Plant to address the hydrogen sulfide
treatment TTHM issue.
TABLE ES-4
Hydrogen Sulfide Treatment Technology Benefits and Drawbacks
Technology
Benefits
Drawbacks
Aeration
Will reduce taste and odors. Low
capital costs.
More effective at lower pHs, which
requires chemical addition. Must
re-pump after aeration.
Catalytic Carbon Adsorption
Effectively controls tastes and
odors with proper GAC selection.
Restricted to applications with
hydrogen sulfide concentrations
less than 0.3 mg/L. Moderate
capital and high O&M costs.
Frequent carbon replacement.
Oxidation with Dual Media or
Greensand Media Filtration
Will significantly reduce taste and
odors.
High capital cost. Media must be
regenerated.
Oxidation with Pyrolusite Media
Filtration
Will significantly reduce taste and
odors. Media does not require
regeneration. Higher filtration
rates possible than with other
medias.
Moderate capital cost.
Ion Exchange
Effectively controls taste and odor
with proper resin selection and
maintenance.
High capital and O&M costs.
Requires acid/caustic
regeneration of media.
Oxidation-Reduction
Effectively controls taste and odor
with proper design and
maintenance.
Requires two chemical feeds.
Oxidation with Membrane
Filtration
Will significantly reduce taste and
odors with proper oxidation
control.
High capital and O&M costs.
Requires complicated membrane
cleaning procedure.
GSWC should consider using the oxidation-reduction process at the Yukon Plant. The
existing GAC contactors can be used to provide hydraulic contact time for the oxidation
reaction before the addition of the reduction chemical. Chlorine dioxide, or a mixed oxidant
compound, needs to be used for the oxidation step to minimize the formation of TTHMs
due to the organics present in the groundwater. Sodium bisulfite would be used for the
reduction step. It is recommended that GSWC bench-scale test this treatment technology to
verify chemical dosage rates, chemical reaction times and its treatment effectiveness on the
hydrogen sulfide present in the Yukon groundwater.
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Treatment System Automation
The existing iron and manganese treatment systems have their own PLC-based control
systems which allow the treatment processes to be operated in automatic or manual modes.
The current treatment system PLC-based controls are considered adequate and do not need
to be upgraded.
The disinfectant chemical-feed systems (sodium hypochlorite and aqueous ammonia) at all
of the Southwest plant sites are manually operated, with the chemical metering pump
stroke and speed controls being manually set by the operator. The water supply delivery
rates from each of the plant sites can change over time due to pressure fluctuations in the
distribution system. Pressure fluctuations are typical in a distribution system due to changes
in water demand patterns and over night reservoir filling operations. With the current
manual operational mode for the disinfectant chemicals, the disinfectant can be over fed or
under fed at various times during the day. Increases in the water supply delivery flow rate
(associated with pressure drops in the distribution system) are the larger problem. Increases
in the supply rate while maintaining a constant chemical does rate results in a lower
disinfectant residual being delivered to the distribution system. In addition, the manual
chemical dosage can result in excess ammonia being delivered to the distribution system,
which can intensify the nitrification problem.
To address these disinfection challenges, it is recommended that GSWC convert their
disinfection systems at the Southwest System plant sites to automatic control systems that
will vary the disinfectant feed rate to maintain a specific disinfectant residual at the point of
delivery to the distribution system. The automated systems will also maintain the proper
ratio balance between chlorine and ammonia to prevent excess ammonia being delivered to
the distribution system. Three disinfection control schemes were developed for the
following facility configurations:
•
10
No Treatment or Reservoir. A compound-loop or dual control scheme is proposed for
this type of facility configuration and is shown in Figure ES-1. The operator will set the
stroke for the sodium hypochlorite chemical metering pump. The measured well flow
rate will be transmitted to the site PLC, and a program in the PLC will automatically
vary the operating speed of the sodium hypochlorite chemical metering pump. A free
chlorine residual will be used to measure the disinfectant residual downstream of the
sodium hypochlorite injection point. The measured disinfectant residual, along with a
feedback residual setpoint control program in the PLC, will be used to trim the chemical
metering pump speed to maintain the desired residual setpoint. Aqueous ammonia will
be injected downstream of the chlorine injection point. The operating speed of the
ammonia chemical metering pump will be varied automatically based on the measured
flow rate to maintain the desired chlorine-to-ammonia ratio. A final combined chlorine
residual analyzer will monitor the final disinfectant residual delivered to the
distribution system. An ammonia analyzer will be used to monitor for excess ammonia,
with an alarm being annunciated if excess ammonia is detected.
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Residual Alarms
SOUTHWEST SYSTEM WATER QUALITY STUDY
Residual Alarms
Chlorine Residual
Speed Control
Flow Rate
Nutting 01 page 139 of 309
FIGURE ES-1
No Treatment or Reservoir Facility Configuration
•
Treatment with Reservoir. The control automation scheme for this facility configuration
is shown in Figure ES-2. A compound-loop control strategy will be used, as described
for the “No Treatment or Reservoir” configuration, to maintain the desired free chlorine
residual to ensure complete treatment and provide an adequate disinfectant residual for
the reservoir. After the reservoir and the booster pumps, a compound-loop control
system will be used to maintain the desired disinfectant residual for the distribution
system. Aqua ammonia will be injected downstream of the chlorine injection location if
a combined chlorine residual is required for the distribution system. The speed of the
aqueous ammonia chemical metering pump will be varied by flow rate. A final
combined chlorine residual analyzer will monitor the final disinfectant residual
delivered to the distribution system. An ammonia analyzer will be used to monitor for
excess ammonia, with an alarm being annunciated if excess ammonia is detected.
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Flow Speed Control
PLC
Chlorine Residual
SH
CMP
FM
PLC
SH
CMP
CRA
A
CMP
CRA
Reservoir
AA
To
Distribution
System
FM
On-Site
Treatment System
CCRA
BPS
Secondary Disinfection System
Primary Disinfection System
Legend
Well Pump
A
= Ammonia
AA
= Ammonia Analyzer
BPS = Booster Pump Station
CCRA = Combined Chlorine Residual Analyzer
CMP = Chemical Metering Pump
CRA = Chlorine Residual Analyzer
FM
= Flow Meter
PLC = Programmable Logic Controller
SH
= Sodium Hypochlorite
FIGURE ES-2
Treatment with Reservoir Facility Configuration
•
Treatment without Reservoir. The control automation scheme for this type of facility
configuration is shown in Figure ES-3. A compound-loop control strategy will be used,
as described for the “No Treatment or Reservoir” configuration, to maintain the desired
free chlorine residual to ensure complete treatment and the proper disinfectant residual
for the distribution system. Aqueous ammonia will be injected downstream of the
treatment system and the free chlorine residual analyzer. The operating speed of the
aqueous ammonia chemical metering pump will be varied automatically based on the
measured flow rate to maintain the desired chlorine-to-ammonia ratio. A final combined
chlorine residual analyzer will monitor the final disinfectant residual. An ammonia
analyzer will be used to monitor for excess ammonia, with an alarm being annunciated
if excess ammonia is detected.
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FIGURE ES-3
Treatment without Reservoir Facility Configuration
Distribution System Disinfectant Residual
The source water disinfectant residuals may not be adequate to maintain adequate residuals
throughout the Southwest distribution system, especially in areas of the distribution system
with long water detention times and/or significant pipeline corrosion. Supplemental
re-chlorination stations may need to be installed within those areas in order to maintain
adequate disinfectant concentrations to minimize the nitrification problem observed in the
distribution system. The number of re-chlorination stations needed to maintain adequate
disinfectant residuals, and their locations within the Southwest distribution system, will be
determined by the distribution system hydraulic model results and water age analysis.
System Operation and Improvement Assessment
A series of water quality simulations were performed using the hydraulic computer model
of the Southwest System. The computer simulations included source tracing, water age, and
chlorine residual decay in the distribution system by applying measured decay rates from
the SDS testing. The water quality analyses were conducted for historical system operation,
as well as for the improved system operation to show the benefit in implementing the
recommended system improvements. This section summarizes the results from the System
Operation and Improvement Assessment TM, which is attached at Appendix E.
GSWC has indicated that the historic operation of the reservoirs (storage tanks) in the
Southwest System did not include regularly exercising of the tanks. The operators tried to
maximize the availability of stored water at all times. From an operational point-of-view,
available storage is good. However, this operational approach increases the detention time
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(or age) of the water in the distribution system. As observed in the results of the SDS
Testing, increased water age results in reduced disinfectant residual, increased DBP
formation, and increased biofilm growth. Therefore, minimizing water age in the
distribution system improves water quality, and should be an operational objective for the
Southwest System.
Recently, GSWC has modified its operation of the system storage tanks to increase the
amount of water that flows through the tanks. On a daily cycle, the tanks are pumped down
when demands are high, and then refilled when the system demands are lower. This
method of operating storage tanks is often referred to as exercising the storage tank.
The hydraulic model was used to calculate the age of the distribution system water for the
historic mode of operating the storage tanks (without exercising them), and for the current
operating mode which includes exercising the storage tanks. The model results indicate that
the historic operating mode resulted in a system water age of up to 120 hours (5 days).
When the current mode of operation was modeled, the results showed a reduction in system
water age to less than 48 hours (2 days). Therefore, these model results show the importance
of water system operation on water quality. However, it should also be noted that if the
water levels are allowed to fall too low in the storage tanks, then fire and emergency storage
may be compromised.
The following observations were made following the hydraulic modeling for water age:
• Operating the Southwest System without exercising the water storage tanks results
in increased water age in the distribution system.
• Operation of the water system should include exercising the water storage tanks to
minimize water age and improve the disinfectant residual in the distribution
system.
• The volume of operational storage needs to be identified for every storage tank in
the Southwest System. Operators should be required to maintain minimum water
levels that will maintain fire and emergency storage in each storage tank at all times.
The computer model was also use to analyze chloramine residual as the source waters move
within the distribution system. Using adequate chemical dosing rates for the supply sources
to maintain a residual of 2.5 mg/L (which assumes improved disinfectant facilities at the
well sites), the disinfectant residuals remained at acceptable levels. In fact, even when the
water age in the storage tanks approached 100 hours, the chlorine residual remained above
1.0 mg/L. This was also true for the blending zones, where groundwater mixes with
imported water. The issues currently associated with water quality problems in the
blending zones are not a problem based on the modeling results for two main reasons:
• The use of automated chloramination for the groundwater supplies will reduce DBP
formation when the supply sources are blended in the distribution system.
• The dose rate for the disinfectant chemicals will be paced to the flow rate of the wells
using automated controls (primary control) and analyzers (secondary residual trim
control). Currently, the groundwater supplies may not always receive adequate
chemical dose rates due to manual operation of the disinfection facilities.
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Automating the facilities and adding analyzers to verify that adequate chemicals are
being injected will improve the stability of the disinfectant in the distribution
system.
The age and condition of the distribution pipelines was considered with respect to water
quality. The concern here was that the unlined metal pipes might be contributing to the loss
of disinfectant residual and/or DBP formation. The results of the SDS Testing indicate that
DBP formation is not significantly changed when in the presence of unlined pipe. However,
disinfectant residual was impacted. When exposed to bare pipe material, the chlorine
residual was significantly reduced in the 4-day tests. There was less impact shown in the
shorter duration tests. Therefore, minimizing water age in the distribution system should be
considered a priority, especially where unlined metal pipe exists in the distribution system.
However, it is not considered cost-effective to replace all of the unlined metal pipe for water
quality purposes. Instead, higher doses of disinfectant chemicals and occasional shock
chlorination may be required where higher water age and unlined metal pipe coexist.
Estimated Costs
The estimated costs to automate the disinfectant facility controls at eleven well sites in the
Southwest System are shown in Table ES-5. Details for these construction cost estimates are
included in Appendix B. These well sites are considered the most critical sites for
chlorination system control upgrades.
Table ES-5
Plant Chloramination System Control Upgrade Estimated Construction Costs
Estimated Costs
Control
Upgrades
Other
Improvements
129 Street
$256,000
$31,000
$287,000
Ballona
$347,000
$0
$347,000
Belhaven
$275,000
$0
$275,000
Chadron
$270,000
$97,000
$367,000
Compton-Doty
$195,000
$0
$195,000
Dalton
$150,000
$0
$150,000
$83,000
$0
$83,000
Goldmedal
$202,000
$0
$202,000
Southern
$213,000
$0
$213,000
Wadsworth
$209,000
$286,000
$495,000
Yukon
$255,000
$0
$255,000
$2,455,000
$414,000
$2,869,000
Plant Site
th
Doty
Total:
SOUTHWEST WATER QUALITY REPORT.DOC
Total
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In addition to the chlorination system control upgrades, several of the plant sites include
other improvements required to implement the chloramination system control upgrades.
Those additional plant improvements are:
129th Plant: Installation of a new 300 gallon aqueous ammonia chemical storage
tank and chemical metering pump in the room where the existing
brine storage tank is located, including electrical and
instrumentation conduit and wiring modifications. Removal of the
existing Severn Trent system, but not salvage value for the
equipment.
Chadron Plant: Modification of the existing reservoir inlet piping to allow flow
through the reservoir, removal of the booster pump that pumps
directly back to the distribution system (upstream of the reservoir),
and relocation of the existing vault and static mixer from the
reservoir inlet piping to the booster pump station suction pipeline,
including chemical piping.
Wadsworth Three-cell masonry chemical building, 100 gallon aqueous
Plant: ammonia chemical storage tank and one aqueous ammonia
chemical metering pump, including chemical piping to the injection
location, and electrical and instrumentation conduit and wiring
modifications.
The estimated costs reflect January 2007 costs, and are referenced to an Engineering NewsRecord Construction Cost Index for the Los Angeles metropolitan area of 8,871.
System Operation: MWD Supplies Only
An exploratory analysis was performed on the operation of the Southwest System to
determine the feasibility of operating with supply being provided from the MWD
connections only and without supply from the groundwater wells. Based on this
preliminary analysis, the MWD only operation option appears to meet the demand in the
Southwest System within the specified pressure range of 40 to 125 psi and within the
velocity requirements under maximum day demand conditions if proposed improvements
are implemented, including the installation of pressure sustaining valves (PSVs) on the
reservoir fill lines at the ground storage tanks (GSTs) and pipeline improvements as
described in Appendix F. The proposed PSVs helped improve system pressures by
restricting the flow rate of water into the GSTs during refill operations. The proposed
pipeline improvements helped improve system pressures by reducing the headloss from the
WB-15 and WB-25 MWD connections. Areas of high elevation in the 350 pressure zone
showed pressures slightly below 40 psi during the tank filling time, so piping improvements
were included in the analysis to minimize these pressure problems.
This exploratory analysis indicates that it may be feasible for GSWC to operate using
supplies from MWD only and with additional system improvements. However, additional
analysis is recommended before this alternative is pursued. This analysis has not evaluated
16
SOUTHWEST WATER QUALITY REPORT.DOC
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SOUTHWEST SYSTEM WATER QUALITY STUDY
the flow distribution between the MWD connections. It is recommended that the additional
analyses include an investigation for the optimum flow settings at each MWD connection.
The additional analyses should also help to define control settings for operation of the GSTs
and associated pump stations to ensure that the MWD connections are providing the
baseline flow and the peaking capacity is being provided by the GSTs during peak hour
demands. The additional analysis should be conducted prior to the design or construction
of any improvements in the Southwest System.
Findings and Recommendations
Despite attempts to maintain a disinfectant residual and eliminate water quality problems in
the Southwest System, GSWC continues to face challenges in dealing with the system water
quality issues. The historic operation of the Southwest System facilities and manual
operation of the groundwater source disinfection facilities has created problems
maintaining adequate disinfectant residuals in the distribution system. The loss of
disinfectant residual allows bacteria to grow in the water system. The presence of bacteria in
the water can appear as positive samples for coliform, nitrification, as well as other forms.
An adequate disinfectant residual must be present in the distribution system at all times to
mitigate the recurring system nitrification and water quality problems.
Maintaining an adequate disinfectant residual in the Southwest System is not as easy as
other systems. There are numerous challenges that must be dealt with. For example, supply
sources (groundwater and imported Metropolitan water) are blended within the
distribution system. The groundwater sources in the Southwest System are disinfected by
chloramination, and the imported Metropolitan water source is also chloraminated.
However, many of the groundwater sources have background ammonia, and the addition
of chlorine is not well controlled. Another challenge involves the variation in flow rates
from the groundwater wells while the chemical dosing rate of the disinfectant remains
constant. This can lead to inadequate disinfectant residuals being delivered to the
distribution system when groundwater flow rates to the system increase. Blending those
water sources with different source water quality and varying disinfectant residual does not
promote good combined water quality. The use of SeaQuest does not provide a substantial
benefit in maintaining chloramine residual in the distribution system but may provide a
benefit in inhibiting further pipe degradation. Water age in the distribution system is
another challenge, with lower water age being required to maintain adequate disinfectant
residuals. Finally, DBP formation, aging unlined metal pipe, and flushing are just a few
more obstacles for the water system operators.
To help GSWC deal with the challenges that they face in the Southwest System, this study
has developed the following recommendations. The recommendations have been
categorized into two phases. The Phase 1 improvements should be implemented
immediately, since they have been identified to provide the greatest benefit for the cost and
are expected to mitigate the water quality problems associated with a low disinfectant
residual in the distribution system. The Phase 2 improvements are only recommended if the
Phase 1 improvements fall short of the desired objective and low disinfectant residuals
continue to be observed in portions of the system. The Phase 2 improvements should not be
considered until after the Phase 1 improvements have been operational long enough to
SOUTHWEST WATER QUALITY REPORT.DOC
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SOUTHWEST SYSTEM WATER QUALITY STUDY
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determine the effectiveness of the improvements. Additional improvements, such as
replacing unlined metal pipe, could help improve water quality, but were not considered
cost effective on their own.
Phase 1 Recommendations
The following improvements are recommended as the Phase 1 improvements:
1-1. Implement operational modifications to exercise the water storage tanks. The water
stored in these reservoirs needs to be flushed through the tanks regularly to
minimize water age. The costs associated with this recommendation are mainly
operational costs and are difficult to quantify. Nevertheless, there should be an
increased cost associated with exercising the storage tanks.
1-2. Convert all of the groundwater sources to automated chloramine disinfection. This
cost will include costs for new capital facilities at those sites that do not already
have chloramination disinfection. Those costs are included in the estimated costs
presented in Table ES-5.
1-3. Construct disinfection system control upgrades at the groundwater well sites. The
costs for this recommendation include the cost of new capital facilities, as well as
increased operational costs with the addition of ammonia to the chlorine. The
estimated capital costs for the 11 well sites that were considered the most critical
total about $2.869 million (in January 2007 dollars).
1-4. Shock chlorination is recommended for biofilm control and removal. Shock
chlorination is recommended in the areas of the system where biofilm has been
identified and is expected to be performed on an annual basis as needed. The
additional costs, if any, for this recommendation were considered negligible.
1-5. Periodic flushing when required. Even with improved control systems, some
portions of the distribution system may still require flushing. These will typically be
dead-ends at cul-de-sac streets and other locations where the pipelines do not loop.
With the implementation of the other recommendations, it is expected that less
flushing will be required. Therefore, the cost of this recommendation should be less
than GSWC’s existing costs.
Phase 2 Recommendations
The following Phase 2 improvements are recommended only if the Phase 1 improvements
do not completely resolve the water quality issues:
2-1. Modify the operation of selected imported water connections and/or between
pressure zones (adjustment PRV settings) to expand Metropolitan imported water
into areas with longer water ages (detention times). The objective of this
recommendation is to force groundwater into portions of the distribution system
where it is consumed quicker to minimize water age. If the Metropolitan supplies
are balanced with connections in other parts of the system there should be little or
no cost associated with this improvement.
18
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2-2. Increase the use of the imported Metropolitan water source within the Southwest
System during specified times of the year. The higher cost of imported water seems
to make this recommendation unattractive. However, if GSWC can increase its
groundwater use in other systems with better groundwater quality, then GSWC
may actually be able to reduce its overall costs by increasing the well production at
locations where less treatment is required.
2-3. Installation of mixing systems in the system water storage tanks. Mixers can be used
to continuously blend the water in the storage tank with incoming water. This
creates a condition called continuously mixed flow, and is very good at minimizing
water age in the reservoir while also increasing the longevity of the disinfectant
residual. The design of mixers (including the type, size, and quantity) will be
specific to each storage tank. Since mixers are not recommended at this time,
construction cost estimates were not developed.
2-4. Construction of re-chlorination stations in the distribution system. Re-chlorination
stations are disinfection facilities that are located within the distribution system as
opposed to being located at the sources of supply. These facilities are used to
replenish the disinfectant that has been consumed while traveling through the
system. Re-chlorination stations can be constructed at a tank site, or elsewhere
within the distribution system along pipelines, to boost the disinfectant residual if it
becomes too low. Since these facilities are not recommended at this time,
construction cost estimates were not developed.
SOUTHWEST WATER QUALITY REPORT.DOC
19
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TECHNICAL MEMORANDUM
Golden State Water Company (GSWC) Southwest
System Model Condition
PREPARED FOR:
Golden State Water Company
PREPARED BY:
Kirsten Plonka/CH2M HILL and Scott Strosnider/CH2M HILL
COPIES:
Dennis Smith/CH2M HILL
DATE:
February 13, 2006
Introduction
This technical memorandum (TM) presents the status of the Southwest System electronic
water modeling data provided to CH2M HILL by the GSWC as compared to the actual
water system as described by various interoffice memorandums, a 2003 Master Plan
document, and as shown in an AutoCAD file (SWEST-2.dwg). The following components
of the water system were compared to the existing water system documents to determine
any deficiencies in the electronic H2ONet water model data.
Pressure Zones
Based on the August 5, 1997 interoffice memo “Southwest System, Review of Water Supply
Facilities”, the Southwest System had three major pressure zones – the Lawndale/Gardena
pressure zone, the Normandie pressure zone, and the Lennox pressure zone. This agrees
with the H2ONet electronic water model data supplied by the client.
However, based on the Southern California Water Company Region II, Southwest District
Southwest System Hydraulic Schematic dated August 8, 2005, the three pressure zones listed
are Athens/Normandie, Lawndale-Gardena, and Dominguez Hills. It is assumed that the
Dominguez Hills gradient is the same as the previous Lennox pressure zone. The hydraulic
grade lines (HGLs) for the three pressure zones are as follows: Athens/Normandie = 350’,
Lawndale-Gardena = 250’, and Dominguez Hills= 310’. The pressure zones are described
below in Table 1.
The existing H20Net model currently has some discrepancies from the information listed
above. Therefore, the electronic water model will need to be updated to reflect any changes
in pressure zones.
Conveyance
The Southwest System includes about 430 miles of pipe ranging in diameter from 2 inches to
20 inches. The existing pipe lengths by diameter are listed in Table 2 and are based on data
in the model.
APPENDIX A_SOUTHWEST MODEL CONDITION TM.DOC
1
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GOLDEN STATE WATER COMPANY (GSWC) SOUTHWEST SYSTEM MODEL CONDITION
TABLE 1
Range of Elevations Served in Each Pressure Zone1
East Side
West Side
Zone
Static Pressure Range
(psi)
Zone
Static Pressure Range
(psi)
250’
30 - 100
250’
65 - 86
310’
65 – 100
350’
65 - 86
1
Southern California Water Company Short Range (2003-2005) and Long Range Master Plans. 2003-2020 of
Water System Facilities for the Southwest System in the Southwest District of Region II, prepared by Region II
Engineering & Planning Department, 12-31-02
TABLE 2
Existing Pipe Lengths by Diameter
Pipe Diameter
Total Pipe Length
(Inches)
(feet)
2
6,724
3
1,469
4
503,799
6
699,896
8
622,324
10
93,599
12
293,945
14
13,049
16
39,577
18
2,229
20
338
Total Feet
2,276,949
Total Miles
431
A comparison of pipeline in the model to those in the AutoCAD (SWEST-2.dwg dated 6-1405) file was made. The model contains majority of the pipes that are in the system, although
it appears that some distribution lines and dead end pipes are still missing from the model.
In addition, in some locations there appear to be discrepancies between how pipes are
connected in the system as compared to the model. An initial overview of the
system/model comparison indicates that these issues appear in several places and will
require a significant level of effort to correct. From a hydraulic perspective, lack of deadend pipes in the model does not impact the model performance. However, incorrect
connections between pipelines do impact model performance. CH2M HILL proposes that
the model be updated by visually comparing to the system in the SWEST-2.dwg file for
2
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GOLDEN STATE WATER COMPANY (GSWC) SOUTHWEST SYSTEM MODEL CONDITION
connectivity issues and missing pipeline. One stumbling block in this exercise is that the
SWEST-2.dwg file does not have a coordinate system associated with it. CH2M HILL
extracted the pipeline portions from this file into GIS and manually rotated them to match
the model file. This rotation is not perfect and produced an offset which means that the
pipes cannot be directly imported into the model, and much be manually drawn into the
model where there are discrepancies.
In addition, the GSWC will need to provide data on all pipe replacements since the
AutoCAD drawing was created in June 2005. These updates will then be incorporated into
the electronic water model.
Storage
Based on the January 7, 1998 interoffice correspondence, Southern California Water Company
Region II – Engineering and Planning, there are 12 active reservoirs serving the Southwest
System. The total storage volume in these reservoirs is approximately 13 million gallons.
Table 3 lists the reservoirs within the Southwest System’s service area.
Table 3
Existing Tanks and Volumes
Name
Volume, MG
Athens Reservoir
1.5
Budlong Reservoir
2.6
Chadron Reservoir
1.5
Gardena Heights
Reservoir
1.5
Goldmedal Reservoir
1.5
Wadsworth Reservoir
1
Wadsworth East
Tank
0.45
Yukon Reservoir
1
Truro
0.25
Total Capacity
11.3
APPENDIX A_SOUTHWEST MODEL CONDITION TM.DOC
3
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GOLDEN STATE WATER COMPANY (GSWC) SOUTHWEST SYSTEM MODEL CONDITION
JA-010 Q.8
The above listed reservoirs are included in the H2ONet model provided by GSWC. The
H2ONet model actually lists the Budlong Reservoir as two reservoirs (Budlong East and
Budlong West) comprising of 1.30 MG each which adds up to the total of 2.60 MG as listed
above. Please see attached system facility data tables for complete tank data collected and
data that is missing.
Booster Pumps
According to the Region II – Engineering and Planning documents, there are 29 pumps
within the system at pump stations and wells. However, the data provided in the electronic
H2ONet model and other documents indicate 54 total pumps in the system. Of the pumps
listed in the H2ONet model and pump test data, 30 of them are indicated as booster pumps
at system pump stations. There are an additional 13 pumps included listed as well pumps
and 11 of unknown type. Of the 54 total pumps, 6 pumps are not included in the model.
Please see attached system facility data tables for complete pump data collected and data
that is currently missing. Some of the pump data was collected from pump testing records
supplied by GSWC, and the rest was compiled from the H2ONet model itself. As can be
seen from the tables, the booster pump data is deficient for many of the pumps.
Wells
Based on the Southern California Water Company Short Range (2003-2005) and Long Range
Master Plans. 2003-2020 of Water System Facilities for the Southwest System in the Southwest
District of Region II, the Southwest System is served by 25 wells. The information gathered
from the master plan, the H2ONet model provided by GSWC, and well testing data
indicates there are 29 total wells in the system. There are 15 wells included in the H2ONET
model and it is assumed that all wells included in the model are currently active. The
remaining 14 wells are not included in the model and 11 are currently assumed to be
inactive. The status of the remaining wells and the status of all the wells both in and out of
the model will need to be confirmed and updated. Please see attached system facility data
tables for complete well data collected and data that are currently missing. The Southwest
System’s water supply is provided by both wells and interconnections. The
interconnections are discussed below.
Interconnections
The Southwest System is served by 20 interconnections. Currently, 11 of the
interconnections are on active status, 5 of the interconnections are designated as emergency
status, and 4 of the interconnections are on standby. The 11 active status and 5 emergency
status connections are included in the H2ONet model. The 4 standby interconnections are
not included in the H2ONet model. Please see attached system facility data tables for
complete interconnection data collected and data that is currently missing. The HGL and
controls for the interconnections have not been supplied.
4
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GOLDEN STATE WATER COMPANY (GSWC) SOUTHWEST SYSTEM MODEL CONDITION
Valves –Transfer Stations
The Southwest System H2ONet model currently contains valves on 5 tank fill lines and 14
PRVs. Please see attached system facility data tables for complete valve and transfer station
data collected and data that is currently missing. The PRV settings in the table were
collected from the H2ONET model itself and will need to be verified by GSWC. The fill line
data control and valve data is deficient as seen in the attached tables.
Service Connections
Service connections were recently evaluated as part of the 2005 Urban Water Management
Plan update. Currently active connections are estimated to be about 50,000. In addition,
GSWC contains records for all historical connection, active or not, that total to over 70,000.
Model Comparison
GSWC supplied CH2M HILL with both the original H2ONet model and various data for the
Southwest System. CH2M HILL compared the data sets to determine the level of effort to
update the H2ONet model to the current data. The areas that need the most verification
and updating are facilities (physical components and settings) and pipes.
Conclusions
The existing H2ONet model provided by GSWC served as a good starting point for
providing a current model of the Southwest System. The existing model is now out of date
and inaccuracies and deficiencies exist in respect to the actual system currently in place.
Attached to this report are facility data tables documenting the facility data that has been
collected so far from the H2ONet model, the master plan, other reports, and field data
including pump testing provided by GSWC. There still are gaps in the data that need to be
completed by GSWC, as indicated by the shaded areas of the tables. Once the completed
tables are returned to CH2M HILL, we will be able to provide a current and accurate model
of the Southwest System.
APPENDIX A_SOUTHWEST MODEL CONDITION TM.DOC
5
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TECHNICAL MEMORANDUM
Hydraulic Model Development and Steady State
Calibration Results – Southwest
PREPARED FOR:
Golden State Water Company
PREPARED BY:
CH2M HILL
DATE:
October 11, 2006
Purpose
The purpose of this technical memorandum is to provide documentation for the work
effort associated with updating the existing hydraulic model for the Southwest water
distribution system. The update includes development and verification of the physical
components represented in the hydraulic model, development of demand estimates,
identification of peaking factors, and the calibration of the updated model with data
collected from field testing. This technical memorandum is organized in the following
manner:
•
•
•
•
•
•
Overview of existing system
H2OMAP facilities development
Existing demand development
Peaking factor identification
Field testing and model calibration
Summary
Overview of Existing System
The Southwest water distribution system is located in Los Angeles County and serves the
Cities of Gardena, Lawndale, parts of Carson, Compton, Hawthorne, Inglewood,
Redondo Beach, Rosewood and the unincorporated areas of Lennox, Athens, West
Rancho Dominguez, Del Aire and El Camino Village. The service area is primarily
characterized by residential and industrial land use. A map of the Southwest water
distribution system is included as Attachment 1 to this document.
The Golden State Water Company (GSWC) obtains its water supply for the Southwest
System from two primary sources: imported water and GSWC operated groundwater
wells. Imported water is provided from the West Basin Municipal Water District
(WBMWD) and the Central Basin Municipal Water District (CBMWD). WBMWD and
CBMWD obtain their imported water supplies from the Metropolitan Water District of
Southern California (MWD). GSWC operates several groundwater wells within the
Southwest system, and has adjudicated groundwater pumping rights in both the West
Basin and Central Basin.
The pipe network for the Southwest system has a total of 441 miles of pipe. Pipe
diameters range from two inches to 20 inches.
Nutting 01 page 154 of 309
HYDRAULIC MODEL DEVELOPMENT AND STEADY STATE CALIBRATION RESULTS – SOUTHWEST
JA-010 Q.8
An overview of the facilities as well as the hydraulic profile of the Southwest system is
provided in Attachment 2.
H2OMAP Facilities Development
GSWC provided CH2M HILL with a running hydraulic model of the Southwest System
in H2ONET. The H2ONET model was converted and updated using H2OMAP, which
provides the following benefits:
•
Better integration of GIS technology with greater mapping features and display
functionality
•
Increased reference formats using numerous input and output options
•
Functionality to move data easily between Microsoft products for presentation and
display
Once the existing H2ONET model was translated into the current version of H2OMAP,
the H2OMAP model was reviewed for connectivity. No major issues were encountered;
however, missing pipes were added. (Both H2ONET and H2OMAP are software
products developed and maintained by MWH Soft.)
After model translation from H2ONET to H2OMAP was complete, it was possible to
update the hydraulic model based on current (2005) facility conditions. The model was
updated to include all system facilities. GSWC provided appropriate information for the
various facility types including wells, imported water supply connections, storage tanks,
valves, pumps, and pipes. Attachment 3 is the facility data GSWC provided CH2M HILL.
Each facility type included in the hydraulic model of the Southwest System is described
here.
Wells
Wells were modeled in H2OMAP as tanks, more specifically as fixed head reservoirs. The
water surface elevation for each well was input as a fixed head based on well drawdown
and groundwater table elevations. The water surface elevation input into the model is
equal to the pumping water level (after drawdown has stabilized). Groundwater
pumping levels were measured during pump tests carried out between June 2004 and
September 2004; GSWC provided this information to CH2M HILL. All operational and
non-operational wells in the Southwest System are detailed here.
Operational Wells
Twelve operational wells were modeled in the Southwest water system. The wells and
their corresponding pumping groundwater surface elevations, depth to groundwater,
and discharge location (system or storage) are detailed in Table 1.
B-2
APPENDIX B_SOUTHWEST MODEL CALIBRATION TM.DOC
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HYDRAULIC MODEL DEVELOPMENT AND STEADY STATE CALIBRATION RESULTS – SOUTHWEST
TABLE 1
Operational Wells Featured in the Hydraulic Model
Hydraulic Model Development and Steady-State Calibration Results –Southwest
Well
Pumping Groundwater
Surface Elevation (feet msl)
Depth to
Groundwater (feet)
Discharge Location
Ballona No. 4
Ballona No. 5
Belhaven No. 3
Belhaven No. 4
Compton Doty No. 1
Dalton No. 1
Doty No. 1
Doty No. 2
Goldmedal No. 1
Southern No. 5
Southern No. 6
-198
-198
-100
-100
-85
-185
-69
-99
-165
-210
-160
318
318
200
200
135
233
122
152
217
294
244
System
System
System
System
System
System
Storage
Storage
Storage
System
System
Yukon No. 4
-285
359
Storage
Yukon No. 5
-220
294
Storage
-121
171
System
th
129 Street No. 2
msl= mean sea level
Non-operational Wells
The Southwest system has fifteen non-operational wells which are listed in Table 2.
TABLE 2
Operational Wells Featured in the Hydraulic Model
Hydraulic Model Development and Steady-State Calibration Results –Southwest
Pumping Groundwater
Surface Elevation
Well
Athens No. 1
Ballona No. 3
Cerise No. 1
Chadron Well #1
Chadron Well #2
Chicago
El Segundo
Southern No. 3
Ocean Gate
Truro No. 4
Yukon No. 1
Yukon No. 2
Yukon No. 3
157th Street
Status
(feet msl)
Depth to
Groundwater
(feet)
Destroyed
Destroyed
Destroyed
Destroyed
Destroyed
Inactive
Destroyed
Destroyed
Destroyed
Inactive
Destroyed
Destroyed
Destroyed
Destroyed
N/A
N/A
N/A
N/A
N/A
N/A
Destroyed
Destroyed
N/A
-100
Destroyed
Destroyed
Destroyed
Destroyed
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
174
N/A
N/A
N/A
N/A
Discharge Location
Storage
Storage
N/A
Storage
Storage
System
N/A
Storage
N/A
Storage
Storage
Storage
Storage
N/A
msl=mean sea level
N/A = Not Available
APPENDIX B_SOUTHWEST MODEL CALIBRATION TM.DOC
B-3
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HYDRAULIC MODEL DEVELOPMENT AND STEADY STATE CALIBRATION RESULTS – SOUTHWEST
Imported Water Supply Connections
All imported water used within the Southwest system is provided by CBMWD and
WBMWD at several service connections. These service connections are modeled in
H2OMAP as a tank, more specifically as a fixed head reservoir. The fixed head input into
the model is equal to the hydraulic grade line provided at the service connection. This is
an accurate representation of the CBMWD and WBMWD connections, because the
connections are set to provide a constant hydraulic grade line (pressure) to the system by
opening and closing a control valve. There is a flow control valve set at these locations as
well that limits the flow to the design capacity of the connection.
Additionally, the Southwest system has nine emergency connections that are normally
closed. Six are with the City of Inglewood and three are within the City of Hawthorne.
Lastly, the Southwest System has one connection with the California Water Service
Company, which is considered inactive. All operational and non-operational imported
water supply connections in the Southwest System are described in the following
sections.
Operational Imported Water Supply Connections
Twelve Metropolitan service connections were modeled; these are listed in Table 3 with
their corresponding fixed-head elevations and pressure settings at the service
connections.
TABLE 3
Operational Imported Water Supply Connections Featured in the Hydraulic Model
Hydraulic Model Development and Steady-State Calibration Results—Southwest
Imported
Water Supply
Connection
Hydraulic Grade
Line (feet)
Capacity (gpm)
Pressure Setting at
*
Connection (psi)
Ground Surface
Elevation (feet msl)
MWD CB-4
314
4,488
84
120
MWD CB-55
265
6,277
80
85
MWD WB-1
256
4,488
91
45
MWD WB-11
231
2,244
87
30
MWD WB-12
255
2,244
95
36
MWD WB-13
250
2,244
89
45
MWD WB-15
350
11,212
91
140
MWD WB-2A
251
9,000
89
45
MWD WB-25
252-348
4,486
85-127
55
MWD WB-30
250
3,366
67
96
MWD WB-31
351
5,610
100
120
MWD WB-33
261
4,488
110
5
* The fixed-head elevation at the service connection is calculated as the sum of the elevation of the centerline of the control
valve and the pressure head from the pressure setting.
B-4
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HYDRAULIC MODEL DEVELOPMENT AND STEADY STATE CALIBRATION RESULTS – SOUTHWEST
Non-operational Imported Supply Connections
Nine service connections are considered non-operational because they are reserved for
emergency use only. Additionally, there is one California State water connection which is
considered inactive. Table 4 provides details.
TABLE 4
Non-operational Imported Water Supply Connections
Hydraulic Model Development and Steady-State Calibration Results—Southwest
Imported Water Supply Connection
Status
Capacity (gpm)
Emergency
2,250
th
Emergency
1,200
Interconnection Yukon- 104 St.
th
Emergency
2,250
Interconnection Yukon-Century Blvd.
Emergency
2,250
Interconnection Century/La Cienaga Blvd.
Emergency
1,250
th
Emergency
1,250
Interconnection 141 /Inglewood Blvd.
st
Emergency
1,250
Interconnection Compton/Stanford
Emergency
1,000
Interconnection El Segundo/Inglewood
Emergency
1,250
Closed
Not Available
Interconnection Century-Prairie Ave.
Interconnection Redfern-95 St.
Interconnection 118 /Prairie Ave.
California State Water
Exported Water Supply Connections
Water from the Southwest System is not sold to other agencies.
Storage Tanks
All operational and non-operational storage tanks in the Southwest system are described
here.
Operational Storage Tanks
The system has 10 ground-level storage tanks. Water from the tanks is pumped into the
system with booster pumps. Table 5 provides the specifications for these tanks, which
were used to represent these facilities accurately in the hydraulic model.
APPENDIX B_SOUTHWEST MODEL CALIBRATION TM.DOC
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HYDRAULIC MODEL DEVELOPMENT AND STEADY STATE CALIBRATION RESULTS – SOUTHWEST
TABLE 5
Storage Tanks Modeled in the Southwest Water System
Hydraulic Model Development and Steady State Calibration Results – Southwest
Diameter
(feet)
Volume
(million
gallons)
Ground
Surface
Elevation
(feet msl)
Bottom
of Tank
(feet
msl)
Overflow
Elevation
(feet msl)
Top of
Tank (feet
msl)
104
1.5
223
223
243
247
Budlong East
112.6
1.3
174.5
174.5
193.5
193.5
Budlong West
112.6
1.3
174.5
174.5
193.5
193.5
Chadron Tank
75
1.5
50
50
94
96
Gardena Heights
80
1.5
116
116
154
156
Goldmedal Reservoir
80
1.5
59
59
91.5
101.5
Wadsworth East
74
0.45
105
105
125
137
Wadsworth West
74
1
105
105
135
137
Yukon Reservoir
80.9
1
72
72
96
96
Storage Tank
Athens Reservoir
Non-operational Storage Tanks
The Southwest system has five non-operational tanks; these are described in Table 6.
TABLE 6
Non-operational Tanks
Hydraulic Model Development and Steady-State Calibration Results—Southwest
Tank
Belhaven Forbay
Status
Removed
Ballona Forbay
Off-line
Dalton Reservoir
Off-line
Southern Reservoir
Removed
Truro
Removed
Valves
The Southwest water system has three hydraulic pressure zones. The system has nine
throttle control valves and 20 active pressure regulating valves, including the valves on
the system’s interconnections. The model also includes 12 flow control valves that limit
the flow from the MWD connections to their stated capacity. The Southwest system does
not contain any pressure sustaining valves (PSVs). The valves are detailed in Table 7.
B-6
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HYDRAULIC MODEL DEVELOPMENT AND STEADY STATE CALIBRATION RESULTS – SOUTHWEST
TABLE 7
Valves
Hydraulic Model Development and Steady-State Calibration Results—Southwest
Name
Type
Location/Zone
Size
Setting
Status
Athens reservoir fill line
Throttle Control Valve
12
N/A
Operating
Budlong Altitude Valve
Throttle Control Valve
18
N/A
Operating
Chadron Altitude Valve
Throttle Control Valve
Athens Tank
Budlong
Reservoir
Chadron
Reservoir
12
N/A
Operating
Dalton Altitude valve
Throttle Control Valve
Dalton Tank
12
N/A
Operating
Gardena Heights fill line
Throttle Control Valve
12
N/A
Operating
Goldmedal Altitude Valve
Throttle Control Valve
Gardena Tank
Goldmedal
Tank
8
N/A
Operating
Manhattan Altitude Valve
Throttle Control Valve
12
N/A
Operating
Wadsworth fill line
Throttle Control Valve
12
N/A
Operating
Yukon Altitude Valve
Throttle Control Valve
N/A
Wadsworth
Tank
Yukon
Reservoir
12
N/A
Operating
La Cienega
Pressure Reducing Valve
250
12
66.73 psi
Operating
WB-25 to Gardena
Pressure Reducing Valve
250
12
78.43 psi
Operating
Inter Yukon/104th
Pressure Reducing Valve
250
12
40.04 psi
Closed
Inter Cent/Yukon
Pressure Reducing Valve
250
12
40.04 psi
Closed
Inter Cent/Prairie
Pressure Reducing Valve
250
12
40.04 psi
Closed
Inter Redfern/95th
Pressure Reducing Valve
250
12
40.04 psi
Closed
Inter Cent./La Cienega
Pressure Reducing Valve
250
12
40.04 psi
Closed
Athens Booster Regulator
MWD WB-25 to
Normandie
Pressure Reducing Valve
350
12
55.03 psi
Operating
Pressure Reducing Valve
350
12
120.25 psi
Operating
Victoria
Pressure Reducing Valve
310/250
N/A
N/A
Closed
Sandlake
Pressure Reducing Valve
310/250
N/A
N/A
Closed
Keene Ave
Pressure Reducing Valve
310/250
N/A
N/A
Closed
120th Street
Pressure Reducing Valve
350/250
8
49.83 psi
Operating
111th Street
Pressure Reducing Valve
350/250
8
47.67 psi
Operating
Imperial Hwy
Pressure Reducing Valve
350/250
10
52.43 psi
Operating
109th Street
Pressure Reducing Valve
350/250
8
47.23 psi
Operating
Normandie to Lawndale
Pressure Reducing Valve
350/250
8
125.23 psi
Operating
Broadway /138th
Pressure Reducing Valve
350/250
N/A
N/A
Closed
Main/138th
Pressure Reducing Valve
350/250
N/A
N/A
Closed
APPENDIX B_SOUTHWEST MODEL CALIBRATION TM.DOC
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TABLE 7
Valves
Hydraulic Model Development and Steady-State Calibration Results—Southwest
Name
Type
Location/Zone
Size
Setting
Status
Avalon/138th
Pressure Reducing Valve
350/250
N/A
N/A
Closed
MWD-1_FCV
Flow Control Valve
250
12
2,000 gpm
Operating
MWD-11_FCV
Flow Control Valve
250
12
1,000 gpm
Operating
MWD-13_FCV
Flow Control Valve
250
12
8,980 gpm
Operating
MWD-12_FCV
Flow Control Valve
250
12
2,244 gpm
Operating
MWD-25_250FCV
Flow Control Valve
250
12
1,500 gpm
Operating
MWD-30_FCV
Flow Control Valve
250
12
3,366 gpm
Operating
MWD-33_FCV
Flow Control Valve
250
12
Operating
CB55_FCV
Flow Control Valve
310
12
3,300 gpm
10,000
gpm
Operating
MWD-15_FCV
Flow Control Valve
350
12
5,600 gpm
Operating
MWD-25_350FCV
Flow Control Valve
350
12
500 gpm
Operating
CB4_FCV
Flow Control Valve
350
12
3,300 gpm
Operating
MWD-31_FCV
Flow Control Valve
350
12
2,244 gpm
Operating
N/A = Not Available
Pumps
Twenty-five pumps located at 14 pump stations were modeled in the Southwest water
system along with 14 wells pumps. Dalton, Goldmedal and Yukon have well pumps and
boosters at the same facility location. Athens, Budlong, Chadron, Gardena Heights, and
Wadsworth have only booster pumps. The remaining plants; 129th St, Ballona, Belhaven,
Compton-Doty, Doty, and Southern have only well pumps. All of these pumps were
defined using a three-point curve, which includes the shutoff head; the design head and
flow; and the high flow head and high flow. This information was available from original
manufacturer pump curves and pump tests carried out between June 2004 and September
2004. GSWC provided all pump test information to CH2M HILL. All pumps in the
Southwest System are listed here, both operational and non-operational.
Operational Pumps
Thirty-nine pumps were modeled in the Southwest water system. The pumps and the
corresponding points that define their pump curves are provided in Table 8.
B-8
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HYDRAULIC MODEL DEVELOPMENT AND STEADY STATE CALIBRATION RESULTS – SOUTHWEST
TABLE 8
Operational Pumps Featured in the Hydraulic Model
Hydraulic Model Development and Steady State Calibration Results – Southwest
Shutoff
Head
(feet)
Design
Head
(feet)
Design
Flow
(gpm)
High Flow
Head
(feet)
High Flow (gpm)
129 St. Well_2
475
375
1,202
270
1,650
Athens Booster A
200
118
459
95
527
Athens Booster B
200
124
978
101
1,106
Athens Booster C
151
136
526
103
1,145
Athens Booster D
164
132
633
109
1,177
Ballona Well 4
330
280
600
180
1,100
Ballona Well 5
644
518
800
322
1,080
Belhaven Well 3
330
246
723
145
1,200
Belhaven Well 4
330
280
600
180
1,100
Budlong Booster C
246
154
1,185
75
1,900
Budlong Booster D
244
151
1,066
67
1,600
Chadron Booster A
291
186
1,544
127
1,750
Chadron Booster B
283
199
1,627
130
1,750
Chadron Booster C
265
186
1,048
96
1,620
Compton-Doty Well
390
325
300
120
825
Dalton Booster A
250
211
531
75
1,230
Dalton Booster B
320
220
1,296
125
1,850
Dalton Well 1
512
449
288
176
980
Doty Booster A
275
211
1,024
84
1,820
Doty Booster B
275
207
1,020
81
1,820
Doty Well 1
264
223
677
128
1,280
Doty Well 2
390
278
875
180
1,320
Gardena Heights Booster A
179
140
1,148
102
3,000
Gardena Heights Booster B
171
154
2,389
75
5,000
Goldmedal Booster A
237
171
738
75
1,100
Goldmedal Booster B
237
176
1,084
108
1,660
Goldmedal Booster C
315
236
819
80
2,020
Pump
th
APPENDIX B_SOUTHWEST MODEL CALIBRATION TM.DOC
B-9
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HYDRAULIC MODEL DEVELOPMENT AND STEADY STATE CALIBRATION RESULTS – SOUTHWEST
TABLE 8
Operational Pumps Featured in the Hydraulic Model
Hydraulic Model Development and Steady State Calibration Results – Southwest
Shutoff
Head
(feet)
Design
Head
(feet)
Design
Flow
(gpm)
High Flow
Head
(feet)
High Flow (gpm)
Goldmedal Well 1
368
255
924
108
2,150
Souther Well 5
640
528
901
304
1,400
Souther Well 6
528
438
713
180
1,500
Wadsworth Booster A
199
158
713
70
1,400
195
152
792
N/A
N/A
Wadsworth Booster C
200
157
383
50
575
Yukon Booster A
313
202
243
130
720
Yukon Booster B
275
198
508
105
1,000
Yukon Booster C
296
203
902
120
1,225
Yukon Booster D
330
184
1,021
112
1,470
Yukon Well 4
492
427
630
180
1,480
Yukon Well 5
400
358
716
180
1,800
Pump
Wadsworth Booster B
1
1
High head and high flow values were unavailable for the Wadsworth Booster B.
N/A= Not Available
Non-Operational Pumps
The Southwest system has sixteen non-operational pumps; these are described in Table 9.
TABLE 9
Non-operational Pumps
Hydraulic Model Development and Steady-State Calibration Results—Southwest
Pump
Status
Reason
Southern A
Not Operating
Removed from Service
Southern B
Not Operating
Removed from Service
Southern 3
Not Operating
Removed from Service
Southern 4
Not Operating
Removed from Service
Belhaven 1
Not Operating
Inactive
Belhaven A
Not Operating
Removed from Service
Belhaven B
Not Operating
Removed from Service
Ballona 3
Not Operating
Not Operating
Removed from Service
Removed from Service
B-10
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HYDRAULIC MODEL DEVELOPMENT AND STEADY STATE CALIBRATION RESULTS – SOUTHWEST
TABLE 9
Non-operational Pumps
Hydraulic Model Development and Steady-State Calibration Results—Southwest
Pump
Ballona D
Status
Reason
Truro 4
Operating
Inactive
Truro E
Operating
Inactive
Yukon 1
Not Operating
Removed from Service
Yukon 2
Not Operating
Removed from Service
Yukon 3
Not Operating
Removed from Service
157th Street Well
Not Operating
Removed from Service
Pipes
The Southwest system has a total of 441 miles of pipe. Pipe diameters range from 2 to 20
inches. Table 10 summarizes the total length of pipe for each pipe diameter.
TABLE 10
Pipes Featured in the Hydraulic Model
Hydraulic Model Development and Steady State Calibration Results – Southwest
Pipe Diameter (inches)
Total Length (feet)
Total Length (miles)
2
7,392
1.4
3
1,584
0.3
4
489,456
92.7
6
704,352
133.4
8
660,000
125.0
10
94,512
17.9
12
307,824
58.3
14
18,480
3.5
16
42,768
8.1
18
2,112
0.4
20
528
0.1
Total
2,423,520
441
APPENDIX B_SOUTHWEST MODEL CALIBRATION TM.DOC
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HYDRAULIC MODEL DEVELOPMENT AND STEADY STATE CALIBRATION RESULTS – SOUTHWEST
Common pipe materials include asbestos concrete, cast iron, ductile iron, PVC, transite,
and steel. The system dates back to the 1920s, with pipe installations occurring
periodically over the last 80 years.
GSWC provided CH2M HILL with an up-to-date pipe network description in the form of
hard copy system maps and an electronic AutoCAD file. The electronic map was
converted to GIS, moved to the correct spatial location and referenced using the State
Plane Coordinate System, and imported into the existing H2OMAP system model.
The existing pipe network provided in H2ONET was visually compared to the up-to-date
pipe network in AutoCAD, and then H2OMAP was updated to reflect these changes. In
some cases, new pipes were added to H2OMAP. In other cases, the pipe diameters were
modified to reflect the most up-to-date information.
A quality assurance/quality control process was completed to ensure that the network
was connected correctly. This process involved looking at where pipes overlapped, where
pipes connected, and where nodes overlapped to identify potential problems. Next, the
model’s pipe network was verified at these specified locations on the AutoCAD maps.
Modifications were made in H2OMAP as necessary.
The Hazen-Williams formula was used to compute the friction headlosses in the system.
This equation is empirically based and requires a Hazen-Williams roughness constant, or
C-factor. The C-factor is a function primarily of pipe material and age.
Existing Demand Development
In order to allocate demand within the H2OMAP model, demand information must be
quantified and appropriately spatially referenced. Demand information was collected and
provided to CH2M HILL by GSWC. Water demand data was comprised of the street
address for each water user and their associated average annual demand. Seven years
(1999-2005) of customer billing records were used to estimate the average annual demand
of each water user. The total average annual customer water use for the Southwest water
system was estimated as 22,117 gallons per minute (gpm) for the seven years of demand
records. However, due to data discrepancies in customer water billing records between
the 1999-2004 data and the 2005 data, only the 2005 data was used in the model with
endorsement from GSWC. The annual average water demand used in the model was
20,327 gpm. The average demand for 1999-2005 is summarized in Table 11.
TABLE 11
Average Annual Demand from Customer Billing Records
Hydraulic Model Development and Steady-State Calibration Results —Southwest
B-12
Year
Average Demand* (gpm)
1999
22,156
2000
23,255
2001
22,218
2002
22,489
APPENDIX B_SOUTHWEST MODEL CALIBRATION TM.DOC
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HYDRAULIC MODEL DEVELOPMENT AND STEADY STATE CALIBRATION RESULTS – SOUTHWEST
TABLE 11
Average Annual Demand from Customer Billing Records
Hydraulic Model Development and Steady-State Calibration Results —Southwest
Year
Average Demand* (gpm)
2003
26,762
2004
17,609
2005
20,327
1999-2005 average
22,117
* Average demand does not include unaccounted-for water.
Customer billing records may also be summarized by water-use category. The
Department of Water Resources (DWR) defines for planning purposes, eight water use
categories which were further narrowed to residential and commercial/industrial. This
deviates from the process used for the other seven master plans, since this data was
analyzed months before the other master plans were started. The residential and
commercial/industrial land use codes are considered appropriate for the type of analysis
being done for both the Southwest Water Quality Study and the Southwest Master Plan.
It is important to note that the water use type did not change the quantity or spatial
allocation of demand.
Geocoding was performed to transform street addresses to spatial locations in GIS. To do
this, street addresses were standardized in an Excel spreadsheet in a format suitable for
geocoding, then imported to GIS to employ the geocoding function. This provided
geocoded service locations. At least five percent of the geocoded locations were spotchecked for accuracy. The geocoded locations were verified by performing a spatial query
to identify the number of geocoded locations within 300 feet of the model network layer.
Any geocoded locations not within 300 feet of the model network layer were listed.
Incorrect geocoded locations were manually moved to their correct locations.
MWH Soft’s demand allocator tool was used to assign demand to each node in the
H2OMAP model that was closest to geocoded locations. If multiple geocoded locations
were the same distance from a single node, then the sum of the demand associated with
those locations was assigned to that single node. Nodes without geocoded locations
nearby were attributed no demand.
It is important to note that this analysis does not include water that is otherwise
unaccounted for. Demand estimates based on customer billing records provided detailed
information regarding the spatial allocation of demand but did not provide an estimation
of how much water is lost or unaccounted for. However, production record data
provided the total water demand to the Southwest system. Annual water sales were
compiled from the customer billing data. The difference between annual water sales and
production records was used to derive value for unaccounted-for system losses. Both
production record data and customer billing records were provided by GSWC. Table 12
summarizes total demand data for the Southwest system.
APPENDIX B_SOUTHWEST MODEL CALIBRATION TM.DOC
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HYDRAULIC MODEL DEVELOPMENT AND STEADY STATE CALIBRATION RESULTS – SOUTHWEST
TABLE 12
Demand Data for 2005
Hydraulic Model Development and Steady-State Calibration Results—Southwest
Demand Parameter
Annual water sales
Gallons Per Minute
a
20,327
Unaccounted-for system losses
Total water demand
a
b
3,480
b
Source: Southwest 2005 customer billing data
Data is based on an average of production data recorded at time of fire flow testing.
23,807
The estimate of 2005 customer water use presented in the UWMP was 22,620 gpm (36,486
AFY). This value was calculated using the population-based projection methodology
outlined in the UWMP. In comparison, the 2005 billing records accounted for 20,327 gpm
and SCADA data accounted for approximately 23,807 gpm of production. For the
purposes of evaluating the adequacy of the Southwest water distribution system using
the H2OMAP model, the billing records were used. The ADD water use assigned to the
model included unaccounted-for water and distributed it in the same pattern as demand
based on customer billing records. The table below presents the results of this
comparison.
TABLE 13
Comparison of Production Record Data, Customer Billing Data, and 2005 UWMP Data for ADD
Hydraulic Model Development and Steady-State Calibration Results —Southwest
Year
Production Record
a
Data (gpm)
Customer Billing Data
(gpm)
2005 UWMP Data
b
(gpm)
2005
23,807
20,327
23,265
a
Data is based on an average of production data recorded at time of fire flow testing.
b
Data is corrected to include 2.92 percent of unaccounted-for water based on 2005 UWMP analysis.
Peaking Factor Identification
To evaluate the adequacy of the Southwest system under conditions such as MDD and
PHD, it was necessary to identify peaking factors. Peaking factors are used to adjust ADD
to estimate extreme demands in the system.
Historical annual and maximum day demand records were provided by GSWC from
both the 1997 and 2003 Water System Master Plan for the Southwest system and from
recent data. Records included water use for the years 1980-2005; both ADD and MDD
were recorded. The peaking factor used in this evaluation was calculated as the average
peaking factor (from measured data) for the years; this peaking factor is 1.30. The peaking
factors for the last 26 years ranged from 1.17 to 1.50 and are shown in Figure 1. Based on
the historical information, a peaking factor of 1.30 appears to be adequately conservative
based on trends over the past 26 years.
B-14
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HYDRAULIC MODEL DEVELOPMENT AND STEADY STATE CALIBRATION RESULTS – SOUTHWEST
1.55
Peaking Factor (ADD to MDD)
1.50
1.45
1.40
Average Peak Factor, 1.30
1.35
1.30
1.25
1.20
1.15
1.10
1980
1985
1990
1995
2000
2005
Year
FIGURE 1
PEAKING FACTOR (ADD TO MDD) FOR THE YEARS 1980 TO 2005
SOURCE: 2005 UWMP
Data from more recent years indicate a decreasing trend in the ratio of MDD to ADD
compared to pre-1990 values. The percent chance of exceedance based on the data from
1990 to 2005 is 33 percent, and the percent chance of exceedance based on data from 2000
to 2005 is 26 percent. These probabilities further demonstrate that a 1.30 peaking factor is
adequately conservative based on trends over the past 5 to 15 years. Table 14 presents this
and additional statistics from GSWC production records from 1980 through 2005, and
Table 15 provides the annual ADD and MDD data for the same period.
TABLE 14
Water Production Data Statistics
Hydraulic Model Development and Steady-State Calibration Results —Southwest
Statistic
Value
Average
1.30
Standard deviation
0.08
Maximum
1.50
Minimum
1.17
Chance of exceedance of average* (1990 to 2005)
33%
Chance of exceedance of average* (2000 to 2005)
26%
* Probability calculated based on a normal distribution curve
APPENDIX B_SOUTHWEST MODEL CALIBRATION TM.DOC
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HYDRAULIC MODEL DEVELOPMENT AND STEADY STATE CALIBRATION RESULTS – SOUTHWEST
TABLE 15
Water Production Data
Hydraulic Model Development and Steady-State Calibration Results —Southwest
Year
ADD (gpm)
MDD (gpm)
Peaking Factor
ADD to MDD
1980
29.27
39.48
1.35
1981
30.12
43.61
1.45
1982
28.45
38.07
1.34
1983
26.67
40.05
1.50
1984
31.97
43.42
1.36
1985
31.97
47.43
1.48
1986
31.21
43.73
1.40
1987
33.39
42.61
1.28
1988
34.21
42.80
1.25
1989
34.17
41.79
1.22
1990
33.47
40.78
1.22
1991
30.05
35.04
1.17
1992
31.38
41.39
1.32
1993
32.16
40.85
1.27
1994
32.95
41.94
1.27
1995
32.40
44.45
1.37
1996
33.55
44.27
1.32
1997
33.93
42.33
1.25
1998
32.45
42.51
1.31
1999
33.48
42.07
1.26
2000
16.57
20.24
1.22
2001
15.73
19.80
1.26
2002
16.17
19.92
1.23
2003
15.81
20.50
1.30
2004
15.87
19.99
1.26
2005
16.61
20.19
1.22
Source: 2003 Master Plan and GSWC production records
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HYDRAULIC MODEL DEVELOPMENT AND STEADY STATE CALIBRATION RESULTS – SOUTHWEST
The peaking factor for MDD to PHD was designated as 1.70 for the years 1980 to 2005.
This value was provided to CH2M HILL by GSWC from the 2003 Master Plan, which was
based on studies of other similar residential systems. Table 16 summarizes the peaking
factors input to the hydraulic model.
Table 16
SUMMARY OF PEAKING FACTORS
HYDRAULIC MODEL DEVELOPMENT AND STEADY STATE CALIBRATION RESULTS – SOUTHWEST
PEAKING FACTOR TYPE
PEAKING FACTOR
ADD TO MDD
1.30
MDD TO PHD
1.70
Field Testing and Model Calibration
To produce actual system operation data, pressure and fire-flow field testing was
conducted throughout the Southwest. This actual system operation data was then used in
the pressure and fire-flow calibration processes, which are presented here along with the
model calibration results for pressure and fire-flow calibration.
Field Testing
Pressure and fire-flow field testing was conducted by GSWC throughout the Southwest
System on February 9-10, 2006. The approach for this task is outlined in a technical
memorandum titled Golden State Water Company Southwest System Field Testing Plan (Field
Testing Plan). This Field Testing Plan is provided as Attachment 4.
Pressure Testing
To monitor system pressures, pressure recording devices were installed for a period of
approximately one day. The pressure recorders were set to take pressure readings at oneminute intervals.
Pressure recorder results represent the system under regular (or static) flow conditions.
The measured pressures were compared to modeled pressure results under regular flow
conditions to determine calibration accuracy.
GSWC was not able to provide detailed pressure logger information due to technical
issues and therefore is not included in this technical memorandum.
Fire-Flow Testing
For fire flow testing, testing hydrants are designated as monitoring hydrants or flow
hydrants. Twelve pairs of hydrants were selected throughout the system as described in
the Field Testing Plan.
During flow testing, a pressure drop was measured in the monitoring hydrant when the
system was stressed by flowing an adjacent hydrant (the flow hydrant). The pressure
drop refers to the difference between the static pressure (before the hydrant is opened)
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JA-010 Q.8
and residual pressure (during the hydrant flows). The calibration accuracy was
determined by the model’s ability to predict comparable pressure drops to those
measured in the field when the model was subjected to a flow situation similar to that at
the time of testing.
Model Calibration Methodology
Pressure and fire-flow calibration were both considered. The pressure calibration was
used to verify water system elevations, tank levels, and pump curve settings. Once the
pressure calibration was finalized, the fire-flow calibration was used to verify pipe
geometry, size, connectivity, and finally friction factors.
Calibration is one of the most important tasks in developing a hydraulic model. Simply
stated, model calibration consists of adjusting a theoretical model to reasonably represent
actual (field-generated) system operation data. The process of calibration begins by
employing the most simplifying assumptions to the modeled system and then employing
more specific information with each calibration step. At the conclusion of each step, the
model results are compared with the field data to determine the model’s level of
accuracy. Once the desired level of accuracy has been achieved, the calibration process is
stopped.
The goal for calibration of the Southwest System was to match at least 90 percent of the
model results to within 10 percent of the field data.
An accurate calibration effort requires an understanding of the boundary conditions in
the water supply system. The boundary conditions for the Southwest System include the
status of pumps, Metropolitan connections, and reservoir levels. These boundary
conditions were provided in the form of SCADA data by GSWC.
Pressure Calibration
The term pressure calibration refers to a steady state calibration when the system is
experiencing normal flow conditions (approximately ADD). To establish a steady state
condition for pressure calibration, the static pressure data was reviewed and
representative values, at approximately one time step everywhere in the system, were
selected. Boundary conditions at the same point in time were estimated based on SCADA
information. A summary of all reservoir water elevations in the H2OMAP model of the
Southwest water distribution system during the two days of field testing is presented in
Table 17.
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HYDRAULIC MODEL DEVELOPMENT AND STEADY STATE CALIBRATION RESULTS – SOUTHWEST
TABLE 17
Storage Tank Water Surface Elevation During Testing
Hydraulic Model Development and Steady State Calibration Results – Southwest
Elevation During Testing (feet msl)
1
2
3
4
5
Scenario
6
7
Athens Reservoir
13
13
12
12
15
18
17
16
16
13
18
15
Budlong East
7
7
6
6
8
9
8
8
8
7
9
8
Budlong West
7
7
6
6
8
9
8
8
8
7
9
8
28
28
28
28
4
4
4
4
4
28
4
28
Dalton Reservoir
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Gardena Heights
8
8
7
7
12
17
15
14
13
9
16
12
Goldmedal
24
24
24
24
24
24
24
24
24
24
24
24
Wadsworth East
7
7
6
6
11
15
13
12
11
8
13
11
Wadsworth West
5
5
5
4
8
10
9
9
8
5
10
8
Yukon Reservoir
13
13
13
17
16
17
16
16
16
13
16
14
Storage Tank
Chadron Tank
a
a
8
9
10
11
12
SCADA from Chadron is considered to be inaccurate due to recording equipment errors
For the calibration process, it was necessary to adjust the demands to those experienced
during field testing. Based on information from each facility in production during field
testing, it was possible to estimate water supply. It was assumed that this supply equaled
demand (including lost or unaccounted-for water) during field testing. The estimated
total demand for each fire flow testing scenario was applied globally to all demands in
the model. Table 18 provides estimates of yield at each production facility during field
testing.
APPENDIX B_SOUTHWEST MODEL CALIBRATION TM.DOC
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HYDRAULIC MODEL DEVELOPMENT AND STEADY STATE CALIBRATION RESULTS – SOUTHWEST
TABLE 18
Yield at each Production Facility during Field Testing
Hydraulic Model Development and Steady State Calibration Results – Southwest
Production (gpm)
Facility
Scenario
6
7
1
2
3
4
5
8
9
10
11
12
Ballona No. 4
815
837
833
829
843
849
828
841
840
843
851
841
Ballona No. 5
794
793
794
795
792
798
798
800
800
791
803
801
Dalton No. 1
235
235
235
225
297
236
271
286
288
247
236
269
Doty No. 1
0
0
0
0
0
0
0
0
0
0
0
0
Doty No. 2
571
571
571
571
565
563
10
10
2
569
563
576
Goldmedal No. 1
964
964
964
964
949
940
942
949
949
962
940
989
Southern No. 5
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Yukon Well No. 5
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
129th Street No. 2
1985
1972
2003
2003
1948
1909
1856
1901
1924
2023 1828
1926
844
1174
845
845
1194
1023
1310
1194
1316
844
1203
1259
0
0
0
0
0
0
0
0
0
0
0
0
MWD WB-1
1090
1195
1344
1344
745
1633
1712
1745
1277
1090
1774
1492
MWD WB-12
1113
1101
1107
1113
1084
1703
2045
1221
1214
1113
1718
1446
MWD WB-2A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
MWD WB-13
0
0
0
0
0
0
0
0
0
0
0
0
MWD WB-15
1965
1852
1737
1836
2241
2647
2915
2576
2455
1965
2515
2370
MWD WB-30
0
0
0
0
0
0
0
0
0
0
0
0
MWD WB-31
0
0
0
0
0
0
0
0
0
0
0
0
MWD WB-33
0
0
0
0
0
0
0
0
0
0
0
0
Wells
Imported Water
MWD CB-4
MWD CB-55
a
N/A=not applicable, no SCADA information was provided for MWD WB-2A
a
SCADA from MWD WB-55 is considered to be inaccurate due to recording equipment errors
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APPENDIX B_SOUTHWEST MODEL CALIBRATION TM.DOC