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8/17/2019 AWWA- Water Audit and Leak detection guide (1992).pdf
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Am erican W der Works Association
Caiifom b-Ne vada Section
of
Water Resources
The Resources Agency
water conservation
auidebook no. 5
Water
Audit
and
Leak Detection Guidebook
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Copiesof thisGuidebook may be obtained
FREEf”:
Stateof California
Damimentof Water Resources
Bdetim &
Reports
P O Box 942836
. . - -.. - -. .
Sacramento,
CA
pQ236-0001
916)
653-1097
Other pblications availableFREE
f”
heDepartmentof Water Resources include:
Catalog ofw ate r ConservationMaten
LeakAudit Software and Users
Manual
Municipal
Leak Detection Program LossReduction - Research &Analysis, by Boyle
I & W C m r c i a l Drought Guidebook
for
Water U tilities
Cme S W s f &trial Water Conservation n the San Jose Area
Seto f
nine
ChecklistsofWater Conservation Ideasfor Businesses
IndustrialWater Conservation Referencesfor:
Engineering.August
1982
Beverage and Bottling
Elec~?cpMng
FoodProcessing
Laundries
P q e r andPackaging
TenilesandDyes
Guidebwkon Conservation-Oriented Water Rates
Urban
Drought
Guidebook
WaterPk” BenefitlCast Analysis Software
for
Water Management Planning
Proposed
Model WaterEfficientLandscape
Ordinance
Landscqpe Water Conservation Guidebook
Agricultural Drought Guidebook
AGWATEROsoftware
How t
Do A n In-School Education Program
Designing a Public Information Programfor Water Conservation
THE COVER
PHOTO
depicts how underground
leaks
canbe detected and located by
listening for
the sounds of
leakage on system contact points, such as hydrants, valves, and
meters.
This
memberof a leak detection crew is using sonic equipment to conduct an initial
listening survey.
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State of Californ ia
The Resources Agency
Water Audit and Leak Detection Guidebook
Fifth in a Series
of
Water Conservation
Guidebooks for
U s e
by
nterested Organizations ,
Inc luding Water Agencies, Waste Water Treatment Agencies,
Government, and Service Grou ps
August 1986
(Revised June 1992)
of
Water Resourc es
r Conservation Office
American Water Works A ssoc iation
Californ ia-Nevada Section
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FOREWORD
An effective way to conserve water is to detect and repair leaks in municipal water systems. This
con trols loss of water that water agencies have paid to obtain, treat, and pressurize. Because water
leaks from the system before it reaches the consum er, water agencies lose revenue and incur
unnecessary costs.
The Califomia Department of Water Resources
@WR
estimates that about
250,000
acre-feet of
water leaks from municipal systems in Califomia each year. DWR's experience in working with
60 ocal water agencies, whose water audits reveal leak detection projects
to
be cost effective,
indicates that leaking water can be controlled at a cost averaging less than $50per acre-foot, a cost
usually less than what a water agency pays fo r the water.
A w ater audit and leak detection program has benefits in addition to the value of w ater control.
Meter testing performed as a part of the water audit will frequently identify customer meters that
inaccurately recordwater use. Recalibrating inaccurate meters
will
result
in
increased revenues
to
the water agency. Early detection of leaks will reduce the chances that the leaks will cause major
property damage to the water agency or its customers. Better knowledge of the location
of
valves
and mains wll allow the water agency to react quickly when em ergencies dooccur.
The first tw o chapters of this Guidebook provide practical methods and sam ple forms for
conducting a water audit. The audit enables one to determine if a leak detection project would
be
cost effective. The third and fourth chapters include instructions for the most efficient way to
detect leaks.
This Guidebook is one of DWR's how to series on step-by-step ways
to
develop specific water
conservation programs. The inside of the front cover lists othe r DWR water conservation
publications. Water conservation assistance and training information can also be obtained from
DWR District Offices which are listed inside the back cover.
This Guidebook, which is jointly sponsored by DWR and the Califomia-Nevada Section,
American Water Works A ssociation (AWW A), reflects the wide participation, experience and
cooperation among AW WA mem bers and the Department.
David N. Kennedy, Director
Department of Water Resources
Michael J. hcG uire, Chairman
California-Nevada Section
American Water Works Association
iii
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CONTENTS
FOREWORD
...............................................................
ACKNOWLEDGMENT .........................................................
O R G A N I Z A T I O N
...........................................................
INTRODUCTION ...........................................................
Purpose of
the
Guidebook ...............................................
B e n e f i t s
of
Water Audits and Leak Detection
D e f i n i t i o n o f a
Water
Audit
Cost
of
a Water Audit
..................................................
D e f i n i t i o n of
Leak
Detec t ion ...........................................
Cost of Leak Detect ion
.................................................
CHAPTER
1.
THE
WATER AUDI T
............................
............................................
Analyze
t h e
Value
of
Water Losses and Corrective Measures
Update t h e Water Audit Annually
..............
Eva lua t e Po ten t i a l Cor rec t ive Measures .................................
Per iod ica l ly Upda te the Master Plan
....................................
.......................................
CHAPTER
2. CONDUCTING
A
WATER
A U D I T
I n tr o du c ti o n t o the Water Audit Worksheet ..............................
Task
1:
Quan t i fy
the
Water Supply
.....................................
Step
1
. I d e n t i f y
A l l
Water Sources
..................................
Map Selection .....................................................
Plo t t i ng Loca t ions o f Sources
.....................................
Id en t i f y i ng Source Measuring Devices
..............................
Step 2
.
Qu ant i f y Water from Each Source .............................
Water Audit Study Period ..........................................
Units of Measurement
..............................................
T ot a l l in g Water Sources ...........................................
Step
3
. Ver i fy and Adjus t Source Quant i t ies .........................
Poss ib le Causes of Meter E r r o r ....................................
Meter
T e s t i n g A l t e r n a t i v e s
........................................
Adjus t ing Source Quan t i t i e s
.......................................Reservoir and Tank Storage Changes
................................
...
I l l
x i i i
x i v
1
1
1
2
2
3
3
5
5
5
5
6
7
a
13
13
13
13
13
14
14
14
15
15
16
17
18
18
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CONTENTS
cont.)
Task 2: Quant ify Authorized Metered Water Use ......................... 19
Step 1
.
Identify Metered
Uses
....................................... 20
Step 2 . Quantify
Metered
Uses
.......................................
21
Meter Lag Corrections ....................................... 21
Step
3
.
Verify and Adjust Metered
Use
Quantities
....................
24
Sampling Residential Meters ....................................... 24
Calculating Total Sales Meter Error ............................... 25
Estimating Increased Revenue
......................................
29
Task
3:
Quanti fy Authorized
Unmetered
Uses
............................ 30
Step 1. Identify Authorized
Unmetered
Uses
..........................
30
Step
2.
Estimate Authorized Unmetered
Uses
.......................... 30
Task
4:
Quanti fy Water Losses ......................................... 40
Step 1
.
Identify Potential Water Losses
.............................
40
Step 2
.
Estimate Losses by Type of Loss
.............................
40
Task 5:
44
References ............................................................. 46
Analyze the Water Audit Results and Consider Corrective Measures
CHAPTER
3
. LEAK DETECTION
47
Visible
and Nonvisible Leaks ........................................... 47
Examples of Underground Leaks
..........................................
48
Value of Recoverable Leakage ........................................... 50
An Overview of Leak Detection Methods
..................................
51
Leaks
You
Can Expect t o Find
........................................... 53
Main Line Leaks ...................................................... 53
Service L i n e Leaks ................................................... 54
Residential
Meter Box
Leaks .......................................... 54
Residential Customer Leaks ........................................... 54
Valve Leaks .......................................................... 55
Miscellaneous Leaks
..................................................
55
v i
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CONTENTS (cont.)
CHAPTER
4 . CONDUCTING
A
LEAK
DETECTION
SURVEY
Preparing for the Leak Detection Survey
................................
Pre-Survey Review ....................................................
Leak Detection Equipnent
.............................................
Selecting Team Members
...............................................
Planning the Survey ..................................................
Leak Detection and Repair Plan
.......................................
Team Training
........................................................
Equipment Tune-up
....................................................
Leak Detection Procedures ..............................................
Initial Listening Survey .............................................
Problems Encountered with the Listening Procedures
Relis tening t o Suspect Sounds ........................................
Pinpointing Leaks ....................................................
Ground Microphone Method ..........................................
Correlator Method
.................................................
Probe Method
......................................................
Excavating the Leak
...............................................
Leak Detection Tips ...............................................
Measuring and Estimating Losses from Discovered Leaks ..................
Calculating Leak Rates for Small Leaks .................................
...................
Determining Leak Detection Effectiveness
...............................
APPENDIXES
APPENDIX A SAMPLE
COMPLETED WATER
A U D I T REPORT AND
LEAK
DETECTION AND REPAIR
PLAN
.......................................
APPENDIX
B
TYPES OF METERS ............................................
APPENDIX C
RECOMMENDED
USES OF METERS BY CLASSIFICATION
...............
APPENDIX
D
METER SIZING PARAMETERS ....................................
APPENDIX E METER INSTALLATION CONSIDERATIONS
..........................
57
57
57
57
58
58
58
62
63
63
63
64
65
65
67
68
71
72
73
75
77
78
83
103
107
111
115
v i
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CONTENTS (ant . )
APPENDIX
F
METER
TESTING I N
GENERAL ...................................
117
APPENDIX G
METER
TESTING WITH A PITOT ROD ............................. 119
APPENDIX
H LONG-TERM METER SURVEILLANCE
...............................
121
APPENDIX I CALCULATING
EVAPORATIVE WATER LOSS ......................... 123
APPENDIX
J
LEAK DETECTION
EQUIPMENT
...................................
125
APPENDIX
K
WATER A U D I T AND LEAK DETECTION BLANK FORMS ................. 127
EXAMPLES
Example
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Water Audit Worksheet
.............................................
System Smnary of Water Source Measuring Devices ..................
Uncorrected Total Water Supply i n 1983
............................
Adjustments t o Source Tot al s Due t o Source
Meter
Error
............
Changes i n Reservoir Storage ......................................
Percent Water Consumption by Meter Size
...........................
Uncorrected Total Metered Water Use ...............................
Billing Cycles Related
to
Water
Audit Periods
Detailed
Meter
Lag Correction
.....................................
Adjusting Residential
Meter
Records for Sales Meter Error
Calculation of Residential Water
Meter
Error
......................
Meter Test Data for Large Meters ..................................
Calculation
of Meter
Error for Large Meters
.......................
Calculation
of Total Sales
Meter
Error
............................
.....................
.........
9
14
15
18
19
20
21
22
23
26
26
27
28
29
v i i
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CONTENTS (cont.)
Example
15 Potential Revenues from Recalibrated Large
Meters
.................
16
17
Estimate of Water Volumes Used by Tank Trucks .....................
18 Estimate of Landscape Watering
....................................
19
Leak Detection and Repair Plan Worksheet
..........................
20 Leak Detection Survey Daily Log ...................................
21 Leak Repair Report
................................................
22 Leak Detection and Repair Project Sumnary
.........................
Calculation of Water Volume from Variable Rate Discharge
..........
ILLUSTRATIONS
1
Yearly Water Distribution
.........................................
2
Nonvisible Leak ...................................................
3
Doorhanger Notifying Residential Customer of
Possible Plumbing Leaks .........................................
4 How a Corr elator Works ............................................
TABLES
Table
Steps in a Water Audit ............................................
Weighting F ac to rs for Flow Rates Related t o Volume Percentages
Value of Recoverable Leakage ......................................
Leak Losses for Circular Holes Under Different Pressures ..........
Leak
Losses
for Joints and Cracks Under Different Pressures .......
Drips per Second
Converted
t o Gallons per Minute
....
..................
Cups per Minute Converted to Gallons per Minute ...................
i x
a
30
33
35
36
59
74
79
81
8
48
64
69
7
25
50
77
77
78
78
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Photographs
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
WATER AUDIT AND LEAK DETECTION GUIDEBOOK
Photographs
&
Illustrations
Caption
L i s t e n i n g
for the sounds of leakage.
How t o use a pitot rod for measuring flow i n a pipe.
Recording pitometers may be used t o measure flows
and cal ibr a te larg e
meters.
Correct meter installations include a small bypass meter,
a debris
screen,
and check valves on both si des of t he
meter.
Comnercial meters may be tested repaired and calibrated
on meter test bench.
Hydrant flushing programs improve water quality.
Records should be maintained of water used for
street
cleaning.
Cemeteries
may be l a rg e water use rs .
Decorative water f a c i l i t i e s
u s e
a lot of
water.
Meter readers
must
cope with different meter dials and
u n i t s of measurement.
Page
Cover
16
17
24
27
32
34
36
37
40
Water s to ra ge tank s may be subject t o overflow and leakage. 43
Visible l ea ks , l i k e t h i s f i r e hydrant, ar e ea si ly found. 47
47
The
flow 49
Nonvisible leaks usually occur underground.
Circumferential break
on
a
6
inch cast iron main.
r a t e was measured a t 98 gpm.
Valves are
excellent
contact points to
l is ten
for sounds
of leakage.
51
Excavating a 53 gpm leak on old steel main.
53
Service l a t e r a l le ak s a r e common i n metalic pipes. This 53
lea k was measured a t 2 gpm.
Meter box leak s a r e sometimes v is ib le . Here leak 54
detection equipment determines
i f
standing water
is
runoff or leakage.
X
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Photographs (cont.)
Number Caption
Page
34 Uncovering leaks require8 carc excavation t o avoid, 72
35 Exercising
the
hydrant valve assists
i n
pinpointing 73
36
75
other pipes and/or
u t i l i t i e s .
the
leak.
Service
l i n e
leaks can be easily repaired by replacing
a portion of the service.
pipe i n l i n e
with
a
test meter
and measure the flowrate.
Sane agencies place the damaged
37
Plast i c services are a lso subject t o deteriora t ion
from
improper installation which results
i n
leaks.
76
x i
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ACKNOWLEDGMENT
The Water Audi t and Leak Detect i on Gui debook
has
been prepared by t he
Cal i f orni a Depart ment of Wat er Resources' (DWR) Of f i ce of Wat er Conservat i on
under a State Assi st ance Grant f romthe St ate Wat er Resources Cont rol Board.
The grant was f unded f romt he Cl ean Water and Water Conservat i on Bond Law
passed by t he voters as Proposi t i on 2 i n 1978.
DWR acknow edges al l of t he publ i c water agenci es t hat par t i ci pat ed i n t he
st at ew de water audi t and l eak detect i on program These agenci es f i el d test ed
t hese procedures and provi ded comment s and suggest i ons t hat cont r i buted t o t he
i mprovement of t hi s Gui debook.
Addi t i onal t hanks are extended t o the many revi ewers and support ers of thi s
Gui debook through i t s devel opment . Speci al cont r i but ors i ncl ude: I an
Bal l ant i ne, Car l Buet t ner , J ohn Cur t i s, Al l en Dei t emann, Max Ew ngt on, Suzanne
Kane, Al an Kenf i el d, Wl l i am Ki ngst on, Gordon Laver t y, Paul McMann, J oseph
Romano, Donal d Vandekar and Dean Wheaden.
thei r t i me, pat i ence, suggest i ons,
and encouragement.
Water conservati on ef f ort s of DWR have been wel l supported by t he Ameri can
Water Works Associ ati on (AWWA) , part i cul ar l y by Davi d Todd, Chai rperson of t he
Cal i f orni a-Nevada Sect i on Water Conservat i on Comni t tee.
The aut hor s especi al l y appreci at e
AWWA' s Cal i f orni a-Nevada Sect i on endorses t he Water Audi t and Leak Detect i on
Gui debook and j oi ns
DWR
i n i t s publ i cat i on. Thanks go to:
Donal d Paf f Chai r man, AWA Revi ew Commt t ee
Lar r y Sear s Member, AWA Revi ew Comni t tee
Phi l l i p Ut i c Member , AWWA Revi ew Commt tee
Gordon Lavert y Chai rman- el ect Cal i f orni a- Nevada Sect i on
Ameri can Water Works Associ at i on
x i i i
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STATE OF CALI FORNI A
Pete
Wilson, Governor
THE RESOURCES AGENCY
Douglas
P.
Wheeler, Secretary
for
Resources
DEPARTMENT OF WATER RESOURCES
David
N .
Kennedy, Director
J ohn J . Si l vei r a Rober t
G .
Potter
J ames U. McDani el
Deput y Di r ect or
Chi ef Deput y Di r ect or Deput y Di r ect or
L. Luci nda Chi pponer i Susan N. Weber
Assi st ant Di r ect or f or Legi sl at i on Chi ef Counsel
OFFI CE OF WATER CONSERVATI ON
J onas Mi nt on
...........................
Chi ef , Of f i ce of Wat er Conservat i on
Kei t h Wat k i ns ..................... Chi ef , Ur ban Wat er Conser vat i on Br anch
Thi s r epor t was wr i t t en by :
Chr i s t opher Car r
..............................
Of f i ce of Wat er Conservat i on
Char l i e P i ke ................................... Of f i ce of Wat er Conser vat i on
wi t h maj or ass i s t ance f r om
Edna Bai l ey .................................... Of f i ce o f Wat er Conservat i on
Pat t i Pal ac i os
................................
Of f i ce o f Wat er conservat i on
Lynda Her r en ................................... Of f i ce o f Wat er Conservat i on
Al i ce Br ooks ................................... Of f i ce of Wat er Conservat i on
Tr av i s L at ham
...........................................
Di vi s i on of Pl anni ng
Sus an Tat ayon ........................................... Di vi s i on of Pl anni ng
Ear l Bi ngham ............................................. Di vi s i on of Pl anni ng
xiv
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SPECIAL NOTE
A l l photographs i n t h i s Guidebook were prepared by the staffs
of Cam unity Co nsu ltan ts, In c. and t h e Department of Water
Resources.
t h i s effort.
W grateful ly acknowledge their contributions to
X V
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INTRODUCTION
Purpose of the Guidebook
This
Guidebook has been prepared t o
help
water agencies reduce water and
revenue losses.
detection surveys of piped, pressurized, potable water distribution systems and
provides:
I t includes techniques for conducting water audits and leak
step-by-step procedures f or conducting a comprehensive systemwide water
audit t o assess th e delivery efficiency of a water dis tri but ion system;
a worksheet and sample forms fo r each s tep of th e
water
audit;
spe cif ic techniques t o iden tif y, quantify, and ver ify a l l water sources,
uses, and losses;
a procedure and form t o cal cu la te increased revenues as a r e su l t of
te st in g and repair of l arg e meters;
alt ern ativ e actions t o correct ident ified problems i n a water system;
a t oo l t o determine whether a leak detection project would be cost
e f fec t ive ,
the
length of time
needed
t o perform a le ak dete ction survey,
and
what equipment is
needed.
step-by-step procedures fo r conducting a comprehensive leak de tecti on
project t o locate nonvisible underground leaks;
forms t o record information
from
surveying the distribution system,
pinpointing leaks, estimating leak losses, and documenting costs of survey
and repair; and
a procedure and
forms
to evaluate the cost effectiveness of the leak
detection project .
Benefits
of
Water
Audits
and
Leak
Detection
Reduced Water Losses
-
Conducting a leak detection project w i l l ident i fy
and locate water system leakage.
w i l l re su l t .
water
and reduced chemicals t o t r e a t water.
Financial Improvement - A water audit and leak detection project can
in cr ea se revenues from customers who have been undercharged, lower costs of
wholesale supplies, and reduce treatment and pumping costs.
Increased Knowledge of
the
Distribution System
- The
added familiarity of
the distribution system gained during a
water
audit and leak detection
pr oj ec t hel ps a u t i l i t y t o respond more quickly t o emergencies such as main
breaks.
Upon repair of
the
leaks, water savings
Savings are also realized in reduced power cos t s t o del iver
1
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o More Ef f i ci ent Use of Exi st i ng Suppl i es
-
Reduci ng water l osses w l l hel p
st ret ch exi st i ng suppl i es to meet i ncreased needs. Thi s coul d hel p def er
the const ruct i on of new water f aci l i t i es, such as a new wel l , r eser voi r , or
t reat ment pl ant .
Reduced Pr oper t y Damage
-
I mproved mai ntenance of a water di st r i but i on
systemcan reduce t he l i kel i hood of proper t y damage and bet ter safeguard
publ i c heal t h and saf ety.
o
o
I mproved Publ i c Rel at i ons
-
The publ i c appreci at es geei ng that i t s water
syst ems ar e bei ng mai ntai ned.
detect i on tasks and doi ng repai r and mai nt enance work make a f avorabl e
i mpressi on.
Reduce Legal Li abi l i t y - Conduct i ng a water audi t and l eak det ecti on
proj ect provi des bet ter i nf ormat i on f or prot ect i on agai nst expensi ve
l awsui ts.
Fi el d teams carr yi ng out water audi t and l eak
o
Definition
of
a Water Audit
A water audi t i s a thorough examnat i on of t he accuracy of water agency records
and systemcont r ol equi pment . Wat er managers can use audi t s t o determ ne thei r
water di st r i but i on systemef f i ci ency. The overal l goal i s t o i dent i f y,
quant i f y, and ver i f y wat er and revenue l osses.
t o sel ect and i mpl ement programs t o reduce water and revenue l osses. Such
examnat i ons shoul d be perf ormed annual l y t o update t he r esul t s of ear l i er
audi t s.
Thi s al l ows t he water ut i l i t y
Cost of a Water Audit
The cost of a water audi t i s t he sumof i n- house work and f i el d work. Total
cost s depend on t he fol l ow ng var i abl es:
o t he si ze of t he servi ce area t o be audi ted
o
t he compl et eness and up- t o-date accuracy of t he water agency' s i n- house and
f i el d r ecor ds, i ncl udi ng meter t est i ng programs and records
o t he ext ent t o whi ch i n- house st af f or consul t ant s are
used
t o conduct
t he audi t
o var i at i ons i n cost s for i n- house staf f or consul t ant s to conduct al l or
a
port i on of t he audi t
Typi cal water audi t act i vi t i es i ncl ude:
o
o
master/ source meter t est i ng
o
ver i f yi ng, quant i f yi ng, and updat i ng: water source i nf l ow r ecords; metered
ver i f yi ng and updat i ng systemmaps
use r ecor ds, such
as
bi l l i ng and account i ng i nf ormati on; and unmetered use
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r ecor ds, such as est i mates of wat er use for parks, c muni t y cent er s,
government f aci l i t i es, and f i ref i ght i ng
o
t est i ng resi dent i al , comer ci al , and i ndustr i al sal es met er s f or accuracy
i nspect i ng wat er measur i ng devi ces for proper si zi ng, i nst al l at i on, and
operat i on
\
o
o
f i el d checki ng di st r i but i on cont r ol s and systemoperat i ng procedures
Any of t he above act i vi t i es coul d be conducted by i n- house st af f or consul t ant s
or both.
The most expensi ve i tem f or
a
water audi t i s l ar ge meter test i ng.
meter test s r ange i n cost s f rom $150 t o $500.
$25 t o $50 each.
meters and sal es meters that must be tested to provi de current dat a f or t he
ent i r e system
Wat er agenci es par t i ci pat i ng i n t he St ate of Cal i f orni a' s water audi t and l eak
det ect i on grant program report ed cost s of water audi ts.
from $2,000 to over
$15,000
dependi ng on the accuracy of i nf ormati on al ready on
hand, t he compl exi t y of t he agency, and other var i abl es.
Large
Resi dent i al meter t est s average
The t ot al f i el d cost depends upon the number of sourcehast er
These cost s r anged
Definition of a Leak Detection
Leak det ect i on i s the syst emati c method of usi ng l i st eni ng equi pment to survey
t he di st r i but i on syst em i dent i f y l eak sounds,
and pi npoi nt t he exact l ocat i ons
of hi dden underground l eaks.
Cost of a Leak Detection
The cost s f or a l eak det ect i on proj ect i ncl ude cost s for l eak detect i on
equi pment and t he l eak detecti on cr ew to survey the system and cost s of
pi npoi nt i ng l eaks, est i mat i ng wat er l osses, and document at i on.
Leak repai r cost s ar e not consi dered a di rect cost.
cont i nual l y di scovered and repai red i n t he normal course of the ut i l i ty' s
oper at i ons, t he l eaks f ound dur i ng the l eak det ect i on program woul d event ual l y
be repai red at some t i me i n the f uture, somet i mes under emergency condi t i ons.
Cost s f or l eak det ect i on cr ews depend upon whether an agency uses i t s own
st af f , a consul t ant , or a combi nat i on of t he two. Leak det ect i on cost s are
normal l y expressed i n dol l ars per m l e of mai n surveyed.
cost s r ange f rom$75 t o
$300
per m l e of mai n. Cost s f or consul t ants r ange
from $250 per m l e of mai n t o $500 per m l e of mai n.
The var i abl es f or l eak det ect i on cost s i ncl ude wage rat es f or l eak detect i on
t eams, t he number
of
cont act poi nt s t o be sur veyed,
spaci ng of cont act poi nt s
t o be sur veyed, t ypes of mai ns and servi ces, accuracy of maps, and t he type of
l eaks t o be pi npoi nted.
Equi pment cost s ar e shown i n Appendi x
J.
Si nce l eaks ar e
I n Cal i f orni a, t hese
3
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CHAPTER 1. THE WATER AUDIT
Water losses,
whether
due t o leakage,
thef t ,
underbilling of customers, or
faulty system controls, represent monetary losses to the water agency.
steps management can take to correct the unproductive elements in the water
supply system.
This
is
water th at the agency has already paid t o obtain , t r e a t , and pressurize.
However, because it i s l o s t ,
the water produces no revenue. Outlined
here
a r e
Analyze the Value
of
Water
Losses
and CorrectiveMeasures
Evaluations of co rr ec ti ve measures should
be
based on the cos ts , feas ib i l i ty ,
and savings t h a t re su lt . Once
the
water audit has been completed,
the agency
w i l l
have
suff ic ien t da ta to
determine
where
the
greatest water losses are
occurring.
pri ori t ies . In se t t ing pr io ri t ie s , th e manager
w i l l
a lso
wish
to incorporate
local constraints. These,
of
course,
ar e unique t o each agency and ther efore
ar e not specified.
Answers to the following questions
w i l l
indicate which corrective actions
should be carried out.
o Where are losses occurring within the system?
o How much water is l o s t
i n
each problem area identified?
o
What co rrec t ive measures ar e
needed
t o reduce
the
water
loss?
o
What
w i l l
be the cost of reducing
the
water loss?
o What savings and benefi t:co st r a t i os w i l l result from reducing the water
loss?
o
When can
the
corrective measures
be
implemented?
This information w i l l give
the
agency
the
data necessary to
set
Evaluate Potential Corrective Measures
Examples of co rr ec tiv e measures t o be evaluated are:
o Perform a leak detection survey and leak repair program.
o
Replace mains
with
his tor y of ser ious leaks.
o
Exercise
valves annually.
o Implement corrosion control procedures.
Update the Water Audit Annually
Once a water agency has conducted a comprehensive water audit, annual updates
provide dat a t o help managers decide how t o ad just p r i o r i t i e s and monitor
progress made on system maintenance.
ident i fy new areas of system losses t o estab lis h
new
annual maintenance goals.
Updating a water audit w i l l usually be
less
expensive than the original audit.
Equally important,
the
update can
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Periodically Update the Master
Plan
The agency' s master pl an i s a val uabl e pl anni ng t ool whi ch can be used t o set
pr i or i t i es and schedul e cor rect i ve act i ons to mai nt ai n i t s wat er di st r i but i on
system
Managi ng
a
water di st r i but i on systemrequi r es cur rent i nf ormat i on on
t he systems del i very capaci t y, mai nt enance, and water qual i t y.
An
updated
master pl an i ncl udes t he f ol l ow ng i t ems associ at ed w t h water audi t and l eak
detect i on programs:
o probl em areas and areas of potent i al water savi ngs i dent i f i ed i n a water
audi t
an anal ysi s of water and cost savi ngs achi eved by corr ect i ve act i ons
a
f easi bi l i t y anal ysi s of cor r ect i ve act i ons based on cost and
organi zat i onal constrai nt s
an anal ysi s of i mproved water systemef f i ci enci es resul t i ng f rompast and
proposed corr ect i ve act i ons
o an anal ysi s of t he possi bi l i t y that greater syst emef f i ci enci es can def er
expansi on of t he del i very system
o
o
o
o proj ected water needs
o an i mpl ement at i on schedul e that i dent i f i es when speci f i c cor r ect i ve
act i ons w l l be taken
updated maps show ng physi cal r el at i onshi ps and char acteri st i cs of t he
system
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YEARLY WATER DISTRIBUTION
Average Daily Use
Total Measured Miscellaneous
Inaccurate Meters
to City Customers
Jan Feb Mar Apr May June July Aug Sep
Oct
Nov Dec
1. Yearly waler distribu tion (courtesy of Communlty Consultant. Inc.)
Introduction to the Water Audit Worksheet
Example 1 , "Water
Audit
Worksheet," on page
9
i s used t o record the r e s u l t s
of t he step-by-step computations involved i n audi tin g a
water
delivery system.
In Chapter
2 ,
ins tru ctio ns direc tin g you t o enter information on cer tai n
l i nes of tine worksheet a r e emphasized by arrows i n th e margins.
The Water Audit Worksheet is presented here to simply fa mi li ar iz e you
with
t h e
computational process and the types
of
data you
w i l l
need.
system w i l l provide
actual
data for your own agency.
Appendix
A
on page
83
is a Sample Completed Water Audit Report and Leak
Detection and Repair Plan which includes a worksheet using data from the
examples in t h i s chapter.
The audit
of
your
a
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EXAMPLE 1
WATER AUDIT WORKSHEET
For th e Water D is tr ic t: -
LINE
1
2
2A
28
2c
3
4
5
6
7
8
9
‘10
ITEM
Uncorrected Total Water Supply
t o th e Distr ibution System
(Total of Master
Meters)
Adjustments t o Total Water
Source
Meter
Error
(+
or
-1
Change
i n
Reservoir and Tank
Storage (+ or
-)
Other Contributions
or
Losses
(+
or
-1
TOTAL Adjustments to Total
Water Supply
(+
or -)
(Add
Lines 2A, 2B, and 2C.)
ADJUSTED TOTAL Water Supplied
t o th e Distr ibution System
(Add
Line
1
and
L i n e 3.)
Uncorrected Total Metered
Water
Use
Adjustments Due t o Meter
Reading Lag Time (+ or -)
Subtotal:
Metered
Deliveries
(Add Lines 5 and
6 . )
TOTAL
Sales
Meter
Error and
System Service
Meter
Errors
(+ or -)
CORRECTED TOTAL Metered
Water
Deliveries (Add
L i n e s
7
&
8.)
CORRECTED TOTAL
Unmetered
Water (Substract l ine 9 from
Line 4.)
Supply
WATER VOLUM E UNITS*
Total
Subtotal Cumulative
---
I I_
--
*
The
units of water iieasurement must
be
consistent throughout the worksheet.
Their
sel ect ion (e.g., acre-feet, mill ions of gallons, hundred cubic-feet)
is
l e f t
t o
the
user.
9
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EXAMPLE
1 cont.)
WATER AUDIT WORK SHEET Page
2 of 4
LINE
11
11A
11B
11c
1ID
11E
1IF
11G
11H
111
11J
11K
11L
11M
12
ITEM WATER VOLUME UNITS
Total
Subtotal Cumulative
~
Authorized Unmetered Water Uses
Firefighting &
Firefighting Training I
Main Flushing
Storm Drain Flushing
--
Sewer Cleaning
-
Street Cleaning
Schools
Landscaping
I n
Large Public Areas
Parks
Golf
Courses
Cemeteries
-
Playgrounds
Highway Median S tr ips
Other Landscaping -
Decorative Water Facilities
Swimming Pools
Construction Sites
Water Quality and Other
Testing (pressure testing
pipe, water quality, etc.)
-
Process Water a t Treatment
Plants -
Other Unmetered
Uses
TOTAL Authorized Unmetered
Water (Add Lines
11A
through
1 M. )
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EXAMPLE 1 cont.)
LINE ITEM WATER VOLUM E
WATER AUDIT WORKSHEET
13
14
14A
14B
1 4 C
14D
14E
14F
14G
14H
15
16
17
18
18A
18B
19
Total
Subtotal Cumulative
TOTAL
Water Losses
(Substract
L i n e
12 from
Line 10.)
Identified Water Losses
Accounting Procedure Errors I
Illegal Connections
System Controls
Reservoir Seepage and
Evaporation
Malfunctioning Distribution
_ _
Leakage
_ _
Reservoir Overflow
_ _ _
Discovered Leaks
Theft __
TOTAL Identified Water Losses
(Add Lines 14A through 14H.)
Potential Water System
Leakage (Subtract
L i n e 15
from L i n e 13.)
Recoverable Leakage
(Multiply Line 16 by 0.75.)
page 3 of 4
UNITS
I _
_
_I
Cost Savings
Dollars per Unit of Volume
-
Cost of Water Supply
-_-----
Variable 0 &
M
Costs
$---.---
TOTAL
Costs P e r Unit of
Recoverable Leakage
(Add
Line
18A t o Line 18B.) $-----I
1 1
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EXAMPLE
1
cont.)
LINE ITEM
WATER AUDIT WORK SHEE T
20 One-Year Benefit fran
Recoverable Leakage (Multiply
L i n e 17 by
L i n e
19.)
Leakage
TOTAL
COSTS
of
Leak Detection Project
(Divide L i n e
21
by
L i n e 22.)
21 TOTAL BENEFITS from Recoverable
(Multiply Line 20 by 2 . )
22
23
Benefit to
Cost
Ratio
Prepared by:
Dollars per
Year
$
Page 4 of
4
-
Name Date
T i t l e
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Task 1. Quantify the Water Supply
Thi s part
of
t he water audi t i dent i f i es, quant i f i es, and ver i f i es t he water
suppl i ed t o the di st r i but i on system
Step
1.
Identify An Water Sources
I dent i f y and l i st al l water sources that suppl y t he di st r i but i on syst em
i ncl udi ng i nt er connect i ons w t h other systems and i ntermt t ent sour ces or
emergency suppl i es.
Map Sel ect i on.
the ent i r e del i very system
l egi bl e and easy t o work w th (a scal e of
1
i nch to
400
f eet i s suggested) .
none i s avai l abl e, t he next choi ces are aer i al photos or
a
regi onal ( ci ty or
county) map, w t h a t ransparent over l ay on whi ch the di st r i but i on mai ns can be
drawn. An al t ernat i ve woul d be t o draw a map t hat meet s your purpose.
Choose a symbol t o represent each t ype of water source:
wel l s; sur f ace di ver si ons such as l akes, st r eams, r eser voi r s; i nt er connect i ons;
and emergency sources.
Sel ect an exi st i ng map that shows t he pr i nci pal mai ns of
The best map f or t he pur pose i s one t hat i s
I f
aqueduct t ur nout s;
Pl ot t i ng Locat i ons of Sources.
di st r i but i on syst emmap.
I dent i f y and pl ot each water source on a
I dent i f yi ng Sour ce Measur i ng Devi ces.
gather dat a t o const r uct a t abl e ( see Exampl e
2)
t hat sumnar i zes i nf ormat i on
about t he measur i ng devi ce at each sour ce (such as meters, Parshal l f l umes,
wei r s, and st r eamgauges).
Vi si t each sour ce l ocat i on and
13
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EXAMPLE 2
SYSTEM SUMMARY OF WATER SOURC E MEASURING DEV ICES
Sour ce 1
I I I
Sour ce
2
Sour ce 3
Type of Measuri ng Devi ce
I dent i f i cat i on Number
(may be ser i al no. )
Fr equency of Readi ng
Type of Recordi ng Regi st er
Uni t s Regi st er s I ndi cat e
Mul t i pl i er (i f any)
Dat e of I nstal l at i on
Si ze of Condui t
Fr equency of Test i ng
Dat e
of
Lat est Cal i brat i on
Ventur i
00002’78-A
Dai l y
Di al
100,000
gal l ons
1 .o
1950
24
i nches
Annual
4/ 1/ 84
Propel l er
8759
Weekl y
Di al
gal l ons
1o
1968
8
i nches
2 years
8/21/ 84
Ventur i
OC - 16
Dai l y
Wi l der Type M
cubi c- f eet
100.0
1955
11.5 i nches
4 mont hs
1
/ 15/ 85
Step 2. Qua ntify Water from Each Source
Water Audi t Study Peri od. Choose a
per i od that i s l ong enough t o anal yze and eval uate t otal systemwat er use.
12- month study per i od st art i ng i n J anuary and goi ng through December
i s
recommended.
year.
I t i s r ecommended that a cal endar year ( J anuary t hrough December) be used i n
order to reduce t he ef f ect s of any meter readi ng l ag t i me.
page 23. )
Sel ect a water audi t st udy per i od.
A
Most water systemr ecor ds are kept by ei t her cal endar
or
f i scal
Ei t her syst emnormal l y makes
12
mont hs of data avai l abl e f or revi ew
( See Exampl e
8 on
Uni t s of Measurement . Choose the measurement uni t s f or t he audi t . Most
water ut i l i t i es record total f l ow measurements i n mul t i pl es of acr e- f eet ,
cubi c- f eet , or gal l ons.
t he audi t .
Not e t he t ype of regi st er used f or each devi ce and ver i f y t he appropr i at e
conversi on f actor t o be
used
when readi ng t he devi ce.
The same measurement uni t s shoul d be used t hroughout
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To tall in Water Sources. Each
meter
normally has some
t y p e
of to ta l l ing
d F V i E e ~ i X € G T . ~ i s t e r san be one
of
two types. Round-reading r eg i s t e r s
have a
series of
small
d i a l s
(pointers) on
t he
regis ter face, regis ter ing a
volume of water
i n
u n i t s , IOs, I O O S , 1,000s and 10,000s of cu bic- fee t or
gallons.
direct-reading dial that shows total units of volume.
Direct-reading re gi st er s have one la rg e
sweep
hand for testing and a
Month
Total
the
amount of water produced from each source
by
month and for the
entire
period as shown
i n
Example 3 (below).
Source 81 Source 112 Source 83
Turnout
Well
Fi eld Ci ty Monthly
W41 Intert ie Totals
acre-feet acre-f eet acre-feet acre-feet
Calcula te th e t o t a l for a l l your water sources during th e audit period and
enter the amount on
L i n e
1
of
the
Water Audit Worksheet.
Step 3. Verify and A djust Source Quantities
The amount of water
supplied t o a water system must be accurately quantified.
Although most product ion sources a re measured by meters,
used, such a s Par shal l
flumes
or weirs. Measurement errors provide incorrect
other devices ar e als o
data.
flow data w i l l inVaTiTii"Fthe e nt ir e y a z t= audit.
Such errors must
be
discovered and corrected because incorrect source
I____ _
~
_ _ _ _ _ - - _ -
-
- - - - - ---- ---- -
rrows
i n
the margin indicate information that is t o be entered on the
water
audit worksheet.
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Review
available
meter test
results for accuracy
w i t h i n
applicable American
Water Works Association
(AWWA)
standards.
standards for i t s category, repair and recalibrate it t o function within
acceptable l i m i t s .
If
no
meter test
resul ts are avai lable ,
test the meter.
Possible Causes of
Meter
Error.
causes other than normal wear.
each production measuring device.
If t he
meter
error exceeds
the
Inaccurate source meters can result
from
Review
th e dis tr ib ut io n system map loc at ion of
Then
inspect each source
meter
in the
f ie ld. Make
the
following checks and act accordingly.
o
Determine
whether the
proper types of meters
were selected
for use.
o
Determine whether
meters
of the proper size were selected for use.
th is agains t
the
manufacturers' recomnended ranges.
o
Determine whether meters were instal led correct ly.
o Determine whether
proper registers were
selected
and installed
correct ly.
o Determine
by inspection
whether
hard-water encrustation
is
present.
o Determine
whether the meter is level .
slope or vertical operation.
Check
Meters ar e usually not designed f or
o
Have an employee other than
the
regular
meter
reader make a special
meter
reading of the master
meters,
or
send
another employee t o accompany the
2.
HOW
to u s e a
pnot rod
for
measuring f low In
a
pipe.
16
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meter reader t o verify the sample readings.
whether
the
reg is te r is being misread and recorded improperly and
the
conversion fa ct or s a r e being improperly used.
p i t m e t e r .
A
partial blockage to
the
throat of t h e meter might
be
present.
adequate for non-turbulent flows.
The
device should
be
tested
a t d i f fe ren t
flow ranges.
If
t h e pressure deflection for appropriate flows is adjusted
without checking th e ven tur i i t se l f , then the meter can s t i l l
be
recording
flows erroneously,
The purpose is t o determine
o
The primary device on a l l ven tu ri meters should be tes ted with a pinpoint
Testing
the
meter
with
a pitometer w i l l determine
i f the
ins ta l la t ion
is
Meter Testing Alternatives.
tested within the l a s t 12 months.
which are
i n
order of effectiveness.
1 . Test the
meter
in place. Retro fi t t in g piping
may
be required.
2.
Test a l l measuring devices t ha t have not been
Choose from among t h e following options
Compare
the
meter
reading
with
readings
of
a calibrated
meter
ins ta l led in
series with the original
meter.
Record meter readings fo r a given flow over a speci fi ed time period.
Remove
the meter
and replace
it with
a calibrated
meter;
record
t h e
readings from the calibrated meter for the same flow over the same period;
compare the readings.
Test
the meter a t a
meter
t e s t i ng fac i l i t y .
3.
4.
Meters can be
tested
either
i n
a
meter
shop or
i n
the f i e l d
w i t h
a variety of
portable equipment.
free by electric u t i l i t i e s ) c a n
be
used to check meters and is provided by
some
e l e c tr i c u t i l i t i e s .
laboratories ar e a lso avai lable.
pitotmeter and
the
r e su l t s may be off by a s much a s 10 percent.
single point pitotmeter mus t
be
used for accurate results.
Pump efficiency
flow
t e s t i ng
(sometimes
provided for
Consultants, meter manufacturers, and spe cia l te st in g
Some el ect r i c ut i l i t i e s use an averaging
A standard
3.
Recordlng pltometers may be used to measure
f lows
end calibrate large
meters.
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Adjusting Source Quantities.
Master meters can either over or under register.
t ha t
i s
inaccurate, adjust the figures t o reflect the variance by calculating
the corrected metered volume ( C M V ) . To calculate the
CMV,
divide the
uncorrected metered volume (UMV) by the measured accuracy of the meter and
subtract
the
UMV
a s shown i n Example
4.
Adjust source data for
meter
inaccuracies.
When you f ind a
master
meter
~~
~ -p:ed
Source Volume
I.D.
EXAMPLE
4
ADJUSTMENTS TO SOURC E TOTALS DUE TO SOUR CE METER ERROR
Percent
Meter Error Calcula tion Corrected
Meter
Error (ME) Meter Metered
Accuracy ME
= UMV - UMV Error Volume
(MA)
O X M A
(ME) (CMV)
Source 1 has a meter accuracy of 95 percent which means that it is under
measuring by 5 percent.
means that it is over measuring by 3 percent.
the
UMV by the measured accuracy of t h e
meter
and subtracting
the UMV.
Source 3 has a meter accuracy of 103 percent
which
Calculate the CMV by dividing
1
6,165 95 (6,165)/0.95)
-
6,165 324.5 6 89.5
2
2,700
100
(2,700)/1
OO
-
2,700
+
00.0
2,700
3 2, 05 103 (2,405)/1.03)
-
2,405
-
70.0 2,335.0
TOTAL ADJUSTMENTS to Source
Meter
Readings Due t o Meter Error R54.5
acre-feet
E n t e r Source Meter Error on
L i n e
2A of t h e Water Audit Worksheet. .C
Reservoir and Tank Storage Changes.
source meters are uostream
from
the s torage fac i l i t i e s .
Remember
that water
These changes must
be
considered
i f t he
flowing out of r e s e h o i r s and tanks adds
t o
th e supply measured in to the
system. If the re se rv oi rs have more water a t th e end
of
the audit period than
a t the beginning,
then the
increased storage was measured by the source meters
but not consumed by the customers.
subtracted from
the metered
supply.
storage,
then
the decreased amount of stored water should
be
added t o th e
metered
supply.
Such increases i n storage should
be
Conversely,
i f there is
a
n e t
reduction
i n
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Reservoi r
nter t he Changes i n Reservoi r and Tank St orage on l i ne 2B of t he Water Audi t
r some water syst ems, t here may be addi t i onal cont r i but i ons or l osses t o the
ot al suppl y.
t ers the water syst embet ween t he mast er source meter and t he f i ni shed water
em such as i nf i l t r at i on i nt o an open channel or l osses f roman unl i ned or
en channel .
ese addi t i ons or l osses shoul d be account ed f or as ot her cont r i but i ons and
osses.
orksheet.
dd t he Source Meter Err or , Changes i n Reservoi r and Tank St orage, and Ot her
ont r i but i ons or Losses t o the wat er suppl y.
he Water Audi t Worksheet.
dd Tot al Adj ust ment s to Tot al Water Suppl y (Li ne
3)
t o Uncor rect ed Tot al Water
uppl y ( Li ne 1) to get Adj ust ed Total Wat er Suppl i ed to t he Di st r i but i on
orksheet.
-c
For exampl e, t here may be an addi t i onal sour ce of suppl y that
Enter Ot her
Cont r i but i ons or Losses on Li ne 2C of t he Wat er Audi t
c
Enter t he r esul t on Li ne 3 of
Enter t hi s on Li ne 4 of t he Water Audi t Worksheet .
4
Start End
Change i n
Vol ume i n Vol ume i n
Vol ume i n
Gal l ons Gal l ons
Gal l ons
Task 2. Quantify Authorized Metered Water
Use
ut hori zed wat er i s water used f or benef i ci al purposes.
et ered del i ver i es, whi ch ar e normal l y sol d t o cust omers ( i ndust r i al ,
mner ci al , r esi dent i al , agr i cul t ur al , and ot her ) ; and
(2)
unmet ered
el i ver i es, f requent l y used f or publ i c purposes.
etered.
er i od sel ected f or quant i f yi ng water f romt he sources.
I t consi sts
of
1)
Al l unmetered uses shoul d be
When car ryi ng out t he f ol l ow ng st eps, be sure t o use t he same t i me
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Step 1. Identify Metered Uses
You a r e now ready t o ide nti fy
metered
uses of water.
as
used
for
quantifying water
from the
sources.
o Ident i fy a l l users of water that are supposed t o have meters.
Use
the
same time period
Accounts can
be
iden t i f i ed by meter s e r i a l number, connection number, ass es so r' s parcel
number, street address, account number, or some ot he r system. Assign each
account t o a meter reading route.
Be
sur e t o include water provided t o other
agencies.
o Prepare meter lists by id en t if ic at io n number and si z e of meter fo r a l l a c t ive
accounts. Sort by type of use, including in du st ri al , commercial,
residential, agricultural, wholesale transfers, and others. The type of
metered
use is important because
i t
can help identify accounts that
represent la rg er volumes of s al es and grea ter p ote nti al revenue earnings, as
shown in Example
6.
Be sur e t o include a l l accounts for which metered use data
i s
available, even
i f
the account is not bi l led .
errors,
improper computer programing,
meter
misreading or other errors..
Unauthorized water use may a l so be occurring.
be checked.
Consider th e po ss ib il it y of accounting procedure
These improprieties should a l l
Please see Task 4, Quanti fy Water Losses (page 4 0 ) fo r methods t o estimate
these and other situations where metered use data is unavailable and potential
water los ses a re possible.
EXAMPLE 6
PERCENT WATER CONSUMPTION BY METER SIZE
>leter Si ze
(in)
Number of
Meters
Percent of
Metered
Consumption
518
314
1
1-1/2
2
3
4
6
11,480
10
338
124
216
15
7
6
70.1
0.1
4.4
2.8
11.7
6.4
2.0
2.5
100.00OTAL
12,196
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Residential
Month acre-feet
Jan.
Feb
.
Mar.
April
May
June
July
Aug
.
Sept.
Oct.
Nov
.
D e c
.
Subtotal
Metered
Industrial Comnercial
Agriculture Subtotal
acre-feet acre-feet
acre-feet acre-feet
450
500
500
550
650
700
800
815
700
500
500
-50
7,115
110
110
110
120
130
150
150
150
140
110
110
110
1,500
-
TOTAL Uncorrected Metered Water
25
25
25
25
25
25
25
25
25
25
25
25
300
-
Use
-0-
-0-
-0-
75
175
230
175
230
200
0
-0-
-0-
1,085
-
585
635
635
770
980
1,105
1,150
1.220
1 o65
635
635
-
85
10,000
10,000
Meter Lag Corrections
Corrections must be made t o
water
sales data when t he beginning and ending
dates for the water audit (t h e source meter reading dates and
customer meter
reading dates) do not coincide.
The
January
1
t o December
31
period,
when
l i t t l e outside watering occurs,
is recamended since i t
minimizes water use
variances caused by sumner landscape watering.
An example of
the
comnon situation is shown i n Example 8 below.
example, the water audit is conducted for the calendar year, the source
meters
are read monthly on the
f i r s t
day of each month, and the customers' meters a re
a l l r e ad on the tenth day of the month.
bimonthly billing cycles.)
supplied and consumed for exactly the same time period.
In the
(The same methods a re app licable t o
The goal is t o c a lcu la t e
the
amount of water
2 1
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EXAMPLE 8
BILLING CYCLES RELATED TO WATER AUDIT PERIODS
D e c .
Jan. Feb. Mar. Apr. May Jun. J u l . Aug. Sept. Oc t . Nov. Dec. Jan.
I I
I_
Water Audit Period January
1
t o December
31
X
x x x x x x x x x x x x
Source
meters
read on the
f irst
of each month
Customer meters read on the tenth day of each month
I n th e above situ at io n, no correction
is
made fo r t he water supplied
through the source
meters
since their reading
occurs on
the same day as the
audit begins and ends.
(January
I ) ,
then the water supplied for January 1 should be subtracted from
the to ta l water
u s e
read.
The customer meter readings ar e read on th e tent h of the month and do not
coincide with the audit period.
The best way to account for changing numbers of customers and changing
water
use patterns
i s
t o p ro ra t e the water use fo r t he f i r s t and l a s t bi l l i ng periods
appl ied t o the water audit .
The f i rs t bill ing period has only t e n days that actuall y occur i n the aud it
period.
Yet
the bil l ing information represents
31
days
of
water
use. If
s a l e s
for that December
11
through January 10 period a re 101.9 acr e-f eet, t he
amount ap pli cab le t o th e au di t period
is:
If
t he l a s t reading (December
31)
was a day l a t e
Therefore, a correction must be made.
101.9 acre feet x
I
o d a y s = 32.87 acre-feet
31 days
Thus only 32.87 acre-feet of the use read on January 10th applie s t o th e
audit period.
Completing the calculations, the re are 21 days a t t h e end on
the
audit period
th at ar e not included i n the billing data collected on December
10. Use for
the last 21 days i n December is obtained from the following January billing,
112.5 acre-feet. The amount appli cable t o t h e au di t period is:
112.5 acre feet x 21 days = 76.20 acre-feet
31 days
Thus 76.20 acre-feet is added t o t he use read on December 10th.
Customer meters a r e seldom a l l read on t he same day.
t o d i f fe r en t
meter
routes and read on different days.
par t icu la r ly i f each customer's meter is read on the same date each month.
Example 9 i l lu st r at es a s i t ua ti on of three reading dates per month.
consumption
i s
prorated for each
meter
route or book.
They ar e usu ally assigned
Therefore, a more
deta i led meter lag correction should be used for each
meter
reading r oute,
Again the
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The
water a ud it period is
the
same a s above, January 1 t o December 31.
t h r ee meter routes are read bimonthly:
B
on
the
10th
of the
month; and route C on the 20th.
EXAMPLE
9
DETAILED METER LAG CORRECTION
The
route
A
on
the
1st of the month; route
The calendar below indicates the beginning and end of the water audit period
and the days of use for each meter route.
January 1 December 31
Water Audit
Period
I
End
--
I_
t a r t
I
December January February December January February
1 10 20 1 10 20 1 10 20 ...... 1 10 20 1 10 20 1 10 20
AAAAAAAAAAAA-
A A A A A A A A A A A A A A A W
BBBBBBBBBBBBBBBBBBBBBBBBB BBBBBBBBBBBBBBBBBBBBBBBB
cccccccccccccccccccccccc
cccccccccccccccccccccccc
Bi ll in g records issued during th e audit report would not include a l l of
the
water used during
the
audit period.
bi ll in g period, issued i n February, actu ally occurred i n the preceding
December.
The
l a s t bi l l in g period, issued i n November and December, would not
include water used i n December.
water used
in December before the audit starte d. Additional corrections
are needed
to
add water used i n December a t
the end
of t h e audit period.
The December through January billing period is 62 days long.
Route Read Date Sales Adjustment
Some
water shown a s used in the
f irst
So, corrections must be made t o su bt ract the
A 2/1/84
12 ac-ft 31/62 = -6.0 ac-ft
B 2/10/84
10 ac-ft 21/62 = -3.4 ac-ft
C
2/20/84
11 ac-ft 11/62 = -2.0 ac-ft
Water Use ................................ -11.4 ac-ft
A 2/ 1
85
13 ac-ft 31/62 = 6.5 ac-ft
B
2/10/85 10
ac-ft
21/62
=
3.4
ac-ft
C
12/20/85
12 ac-ft 11/62 = 2.1 ac-ft
Water Use
................................ +12.0
ac-ft
+0.6 ac-ft
Many water utilities have combined t h e i r accounting and billing procedures into
a computerized format t o
make
t h e foregoing procedure easier and quicker.
Enter Adjustments Due t o Meter Reading Lag time on Line 6 of
the
Water Audit
Worksheet.
2 3
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Add
a l l
metered
deliveries and enter
the
t o t a l on L i n e 7 of the Water Audit
4
Worksheet.
Step 3. Verify and Adjust Metered Use Quantities
Because of their la rg e number, not a l l sa le s
meters
can feasibly
be
inspected
and
tested
annually. W
recmend
instead that you annually inspect and
test
a l l meters t ha t a re
mre
than two inches
i n
diameter and conduct a random
sample of meters equal t o or less than two inches in
diameter.
Review
your agency's practices on meter se lection, s iz ing , and ins ta l la t ion to
see whether present practices permit accurate operation and, i f not, which
practices should be revised (see Appendixes B,
C, D ,
and E for references).
Cornmercial and industrial
meters
produce a much larger share of revenue per
account than do res ident ia l
meters.
Commercial and industrial accounts should
be
inspected for proper type, si zi ng , and ins tal la ti on .
t ha t a l l
new
l a rge meters be inspected and tested before use.
meters
are accurate.
Sampling Residential Meters.
t o inspect and test.
t i a l
meter
t e s t i ng
w i l l
require test equipment that
differs
from that used for
larger meters.
factorv or a consultant for testing. (Refer t o American Water Works Associat ion.
I t i s
a l so recommended
Not a l l new
Choose a random sample of residential
meters
W suggest tes t in g a t lea st
50
t o 100
meters.
Residen-
Residential meters may
be
tes ted on a test bench or sen t t o the
~~
AWWA, publication No. M6, Water
Meters
- Selection, Installation, Testing, and'
Maintenance, Chapter
6 ,
"Maintenance and Repair of Displacement
Meters
. I)
4.
Correct m eter installations Include
a
small byp ass meter, a debrls screen,
and check valves on both sides of the
meter.
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Many agencies a re involved i n a meter change out program.
If
you are involved
in such a program, be sure t o include i n the randcm sample some of the meters
being replaced
so
you can calculate t h e appropriate
meter
error for the e n t i r e
res ident ia l
meters
before use.
Calculating Total Sales
Meter
Error.
meter errors from a l l
meter
size s-- resi dent ial, commercial, and in du st ri al .
Residential
meters
are normally tested a t low, medium, and high-flow ra tes .
The registration data, normally expressed i n percent accuracy, is used to
calculate the t o t a l meter erro r a t average flow rates .
which follow, demonstrate how t o use your ex is ti ng
meter
test data and
ca lcula te to ta l res ident ia l
meter
error .
Table
2
was produced for 5/8
x
3/4
inch
water
meters
from information
i n
an
a r t i c l e by Penchin Tao wri tt en fo r Journal of th e American Water Works
Association, (" St at is ti ca l sampling technique for cont rol ling the accuracy
of small water meters," June 1982").
meter oper ates a t each flow ra te ; the range of flows for each flow ra te ; and
t h e
average
flow
for low, m e d i u m , and high flows.
system. I t is
reconanended t h a t you
test
a representative sample of
the
new
Total sales
meter
error includes
Examples 10 through 14
The
table shows the percent of
time
the
Percent of Time Range in
GPM
Average GPM Percent Volume
Percent Volume
refers
t o the proportion of water consumed a t the specified flow
r a t e , as compared t o t he t o t a l volume consumed a t a l l ra te s.
2.0 percent of th e t o t a l water consumed occurs a t
t h e
low-flow range of
approximately 0.5 t o
1
gpm.
Instead of using the percentage of volumes a s shown above, you may want t o
recording meters, you can
determine
the actual flow rates for your customers'
water meters.
Therefore, only
compute your own percentage volume data. By using special dual meter yokes and
25
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EXAMPLE
10
ADJUSTING RESIDENTIAL METER RE CORDS
FOR SALES METER ERRO R
Volume
(VI)
Residential meter records were adjusted using total residential water sales
data
from
Example 7, Uncorrected Total Metered Water Use, and t h e following
meter
test data.
METE R TESTING DATA FROM A RANDOM SAMPLE OF 50 METERS
Test Flow Rates
Mean Registration i n Percent
Low flows (0.25 gpm) 89
Medium flows (2.0 gpm) 95
High flows (15.0 gpm) 94
Total Volume
Sal es a t Flow
Meter
Meter Error (ME)
Volume Rate Regist ra tion ME
=
V f
-
V f
( V t ) ( V f )
( R ) ( O X l R )
Meter Error
(ME)
( i n
ac-ft)
17.6
63.8 7,115
4,539.4 95 [(4,539.4/0.95) - 4,539.41 238.9
34.2 7,115 2,433.3 94 [(2,433.3/0.94) - 2,433.31 155.3
__
1
I_
100.0 7,115.0 TOTAL Residential Meter Error
=
-12.1
To calcu late to t al meter error for large meters, u s e your mean registration
da ta a s shown i n Example
12.
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EXAMPLE
12
METER TEST DATA FOR LARGE METERS
Meter
ID
No.
Date of
Meter Installa- Manufac- Test Mean Registration at
Size Type tion turer Date Various Flow Rates
Low Medium
-
XYZOOl
3
in
Turbine
6/83
Rockwell
10/84 89 85 100
XOOZAA
3
in
Turbine
6/83
Rockwell
10/84 70 88 98
NB123 4 in
Displace
7/80 Sparling
10/84 95 99
102
NE456 6
in
Compound
9/77
Sparling
10184 98 92.5 102
MOO2
6
in Propellor
5/66
Hersey
10184
_.
8
-
8
-
03
Sum
of Mean Registrations
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
450 462.5 505
Mean Registration for
5
Meters Tested
------------------- 90 92.5
101
5.
Comm ercial meters m ay be tested,
repaired and calibrated
on
a meter
test bench.
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EXAMPLE
13
CALCULATION OF METER ERROR FOR LARGE METERS
Volume
(%V I
Flow recordings
were
made fo r 24 hours in Jul y and February 1984 and indicate
the percent of
volume
delivered by large meters a t low, m e d i u m , and high-flow
ra te s a s fol lows:
Low
10
percent
M e d i u m 65 percent
High 25 percent
From t h i s information
the
to ta l sa le s volume for l ar ge
meters
was adjusted
a s
follows:
~~~~ ~
Total Volume
Sales
a t
Flow Meter Meter Error (ME) Meter Error
Volume Rate Registration
ME
=
V f
-
V f
(ME)
( V t ) ( V f 1 (R)
(0Xl)R ( i n ac-ft )
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EXAMPLE 14
CALCULATION OF TOTAL SALES METER ERRO R
Total Sales
Meter
Error (TSME)
=
Residential
Meter
Error
+
Large
Meter
Error;
therefore,
from the totals in Examples
11 and 13, the TSME is:
TSME = 412.1
+
92.0
TSME
=
503.74 acre-feet
E n t e r
adjustments for Total Sales Meter Error on
L i n e 8
of the Water Audit
4.
Worksheet.
Add
Line 7 t o Line 8 and enter
the
total on Line
9 ,
Corrected
4
Total Metered Water
Deliveries.
Estimating Increased Revenue.
water audit
s the
potential increase in revenues from test ing and repairing
One of
the
major benefits of conducting a
t h e
larger
meters.
large
meters
found t o
be
operating inaccurately.
Again,
t h e
calculat ion for
the
corrected
metered
volume,
CMV,
for each
individual
meter
uses the following formula:
One
can estimate changes
i n
revenue from customers
w i t h
UMV
= O M R
Where
Uncorrected Metered Volume,
UMV,
is the volume of water registered on
the meter
(from
the
b il li n g records), Mean Registration,
MR, is t h e meter
accuracy i n percent.
For Example:
UMV
= 10,000 cubic-feet (from bil l ing records)
MR
= 75% (r eg is tr at io n accuracy
determined
by meter
tests)
10
000
cMV o 75)
=
13.333
cubic-feet
29
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EXAMPLE
15
POTENTIAL REVENUES FROM RECALIBRATED LARGE METERS
(2)
( 3 )
Uncorrected Charges
Metered Billed
( 1 )
Volume
12 months
Meter I D (UMV) $
(4) (5) (6)
Corrected Charges for
Increased
Metered
Corrected Revenues
Volume Volume
$
(
CMV)
12 months Col
5 -
Col
3
$
Task 3. Quantify Authorized Unmetered Uses
Step 1. Identify Authorized Unmetered Uses
Many water u t i l i t i e s have some unmetered beneficial uses of water.
generally called authorized unaccounted-for
water.
sca tte red throughout the servi ce area a t public buildings, open-space public
areas, and special f ac i l i t i es designed to protect
the
public.
conducting an audit must conEirm
these uses
as unmetered in their service area.
The following authorized uses of water a r e frequently unmetered.
These
are
They a r e most o ft en
Employees
Firefighting and Fire-
fighting Training
Flushing of Mains
S t o rm
Drain Flushing
Sewer Flushing
Street Cleaning
Schools
Landscaping i n Large Publ ic Areas
Decorative Water Facilities
Swimning Pools
Construction Sites
Water Quality and
Other
Testing
Process Water a t Treatment Pl an ts
NOTE: If
any
of these
uses are
metered,
they should
be
included with
Uncorrected Total
Metered
Water Use ( L i n e
5).
Step
2.
Estimate Authorized Unmetered Uses
Unmetered volumes of water must be ca re fu ll y estimated t o produce an accura te
water
audit.
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t he durat i on of operat i on ( di scharge procedure). Survey al l l ocat i ons
( such as school s, st or es, apar t ment s, i ndust r i al si t es, l umber yar ds, or ware-
houses) and i nspect check met ers t o acqui re such data.
survey, t he bet t er your chances of i ncl udi ng water used i n t est i ng, l eaky
spr i nkl er syst ems, or i ncorrect l y connected spr i nkl er systems.
Add
t he r esul t s t o det ermne total water use f or Fi ref i ght i ng and Fi r ef i ght i ng
Fl ushi ng of Mai ns. Thi s water use i s def i ned as unmetered water vented
f r omt he di st r i but i on system ( f requent l y t o stormdrai ns) t o cl ean t he system
of cont amnant s and debr i s.
Many ut i l i t i es have st andard f l ushi ng procedures and mai nt ai n l ogs of f l ushi ng
act i vi t i es, i ncl udi ng t he l ocat i on of t he mai n or bl owof f and the l engt h of
t i me i t f l owed.
Some agenci es even meter t he amount of water rel eased. As
w t h al l wat er uses, i f met ered, t he t ot al shoul d al ready be i ncl uded i n Li ne
5,
Uncor rected Tot al Metered Water Use.
Est i mat i ng wat er used i n the f l ushi ng of mai ns requi r es a seri es of di schar ge
est i mates. For each l ocat i on f l ushed, mul t i pl y the f l ow r ate by t he dur at i on
of t he di scharge.
m nut es equal s 1,500 gal l ons of water. I f t he di schar ge r at e i s not const ant ,
cal cul at e t he vol ume by f i gur i ng t he area under a curve.
di scharge f l owed const ant l y for
10
mnutes at 50 gpm was uni f ormy r educed t o
10 gpmover t he next
15 m nut es, and was then shut of f .
The mor e compl et e your
Tr ai ni ng and ent er t hi s on Li ne
11A
of t he Water Audi t Worksheet .
For i nst ance, 50 gal l ons per m nut e (gpm rel eased f or 30
I n Exampl e 16, t he
6.
Hydrant flushing prog rams
water quality
improve
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Storm Drain Flushing.
used
t o f l u s h and clean such areas as storm drains, culverts, or catch basins,
is defined as storm drain flushing water use .
To
estimate the total water used for
storm
drain flushing, contact the
readings.
system,
f l u s h mains (discharge).
method.
Enter the total water volume used for storm drain flushing on L i n e 11C of
Sewer Flushing.
used t o f lus h and clean sewers and additional water used i n sewage treatment
plants for treatment processess and maintenance is defined as sewer flushing.
Water from the distribution system ( f i re hydrants)
maintenance department for logs of cleaning activity, including truck
cap aci ti es, number of trucks, truck f i l l i n g frequency, and por tabl e
meter
I f
t he
water
is
supplied directly
from
th e piped dist rib uti on
follow the
same
methods as those used
i n
estimati ng water used t o
If the water is transported by truck, use th e batch
the Water Audit Worksheet.
Water from the distribution system (usually f i re hydrants)
Follow the above Storm Drain Flushing procedure t o est ima te the total water
used for sewer flushing.
Enter
the total water volume used for sewer flushing on Line 11D of t h e Water
Audit Worksheet. c
Street Cleaning.
by direct release from hydrants or sprayed from trucks, sweepers, or other
equipment.
areas, and bikeways.
Estimates usually
w i l l
require
use
of
the batch method.
street department t o find o ut how many times a day the tank trucks and sweeping
equipment were f i l l e d , th e number of trucks used, t he truck capacity, and th e
number of days used during t he year.
frequency of use for washing recreational ramps and paths. I n Example 17 the
to ta l ga l lons used annually
was
1,750,000.
This water
u s e
is defined as
water
used t o clean roadways
I t inclu des cleaning park walkways, boat ramps, bus stop s, parking
Check with the
A l s o identify the equipment type and
7.
Records should
be
malntalned
water used for street cleaning.
of
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8.
Cemeteries may
b e large water
users.
To est i mate t he di schar ge f or l andscapi ng, you w l l need t o know 1) t he
di schar ge r ate at each suppl y pi pe to an i r r i gat ed area, and
(2)
t he t ot al
amount of t i me t he water i s appl i ed at each area. Ti me cont rol l ed i r r i gat i on
syst ems make t he t i me determnat i on easi er.
remember t o use the tot al t i me t he suppl y servi ce i s di schargi ng,
rat her than
j ust t he subper i od f or one l ateral .
I n maki ng these est i mates,
EXAMPLE 18
ESTIMATE OF LANDSCAPE WATERING
A si ngl e 2- i nch ser vi ce provi des i r r i gat i on wat er t o 4- 1/ 2- acre Sunnysl ope Park
at t he r at e of 160 gpm
water and i s cont rol l ed by
a
common t i mer.
Lat er al A operates from 1:00 a.m t o 3:OO a.m
3:OO a.m t o 5: OO a.m Lat er al C operates f rom5:OO a.m t o 7:OO a.m
The system i r r i gat es accordi ng to the f ol l ow ng schedul e:
May and Sept ember
..........
every 3rd day
J une ....................... every 2nd day
J ul y and August
............
dai l y
Each of t hr ee l at eral s provi des equal amount s of
Lat eral
B
operat es f rom
How much water i s appl i ed f romMay t hrough Sept ember?
t he answer :
The ser vi ce suppl i es
160
gpmor 9,600gal l ons per hour (160 x 60).
oper ates 6 hours each day t he park i s watered.
gal l ons per hour x
6
hour s = 57, 600 gal l ons
of
water appl i ed.
Here' s how t o work out
I t
Dur i ng t hose si x hour s, 9,600
The number of wat er i ng days must now be cal cul ated:
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The principal components of normal water l os se s from open-air, standing bodies
of water are:
o evaporation
o
water d rained from a pool during maintenance
o
water used for cleaning
o
leaks
To estimate the evaporative loss components, refer to Appendix I (page 1 2 3 ) .
To estimate the water loss from pool drainage, use
the
following data: th e
volume of the
p o o l ,
t h e l i k e l y level t o which t h e pool evaporated before being
drained, and
the
frequency of draining.
Use t h i s
formula:
V x F = V w
V = volume of pool a t time
i t
is drained
F
=
frequency of pool draining
Vw =
volume of water
loss
due t o pool drai ning
To
estimate the water lost
i n
cleaning, f i rs t t a l k t o the maintenance people
involved. They can identify cleaning and flushing frequencies and pool
volumes.
source is a hose b i b
from
a metered fac i l i ty , no further ca lcula t ion
is
necessary.
For an unmetered water source ask how much time th e maintenance work r eq ui re s
a f t e r the pool is drained.
running during
t h i s time.
r e f i l l
pipe,
or
hose, and calculate
the
volume used.
To estimate the
losses from leaks i n decorative water f ac i l i t i e s , you can
sub tra ct th e average amount t h at should be l o s t t o evaporation
from the
normal
water volume. The difference
is
water t ha t i s leaking from the f a c i l i t y .
After you have estimated the four components of water losses (evaporation,
drainage, cleaning, and leaks) add t he results to obta in a tota l for t h i s type
of water loss.
buildings) w i t h i n your s er vi ce area.
E n t e r
the
total water volume used for decorative water facilities
on
L i n e
1 l H C
of th e Water Audit
Worksheet.
They most l i k e l y use a hose from some convenient source. I f the
Ask i f the unmetered hose or
ref i l l
pipe was
Determine
t h e
flow rates for
the
appropria te o ut l e t ,
Add
the
losses by type of f a c i l i t i e s (fo r example, parks
or
Swimnin
Pools. This
water use
is
defined as water used t o maintain volume
and walkways, and operat ion of assoc iated s an it ar y and drinking water f a c i l i -
ties.
Any unmetered water use by concessionar ies th a t depends on t h e service
t o the pool should a ls o be included.
Pools
w i l l
probably
be metered, i n which
case the i r use w i l l already
be
counted
as a metered use.
S w a
--Ir
qua i t y , inc lud ing make-up water,
f i l te r
cleaning, cleaning of
decks
If they are not,
determine
unmetered water uses by pools and
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associ at ed f aci l i t i es f rom i nf ormat i on provi ded by oper at i ons and mai nt enance
staff.
of si ml ar si ze and use.
Enter t he t otal water vol ume used f or al l unmet ered pool f aci l i t i es on Li ne
111 of your Water Audi t Worksheet .
Const ruct i on Si tes. Wat er use at const ruct i on si t es i s def i ned as water
pr i nci pal l y del i vered through hydrant s t o t r ucks f or road dust cont r ol , si t e
pr eparat i on, l andscapi ng, temporary domest i c use, and mat er i al s processi ng ( f or
exampl e, concr ete mxi ng).
To est i mate t hi s t ot al water use, obtai n consumpt i on dat a f rommetered
const r ucti on si t es f or si ml ar proj ects.
wat er agenci es. Compare a contra' ctor' s pract i ce i n shut t i ng of f suppl y at
unmet ered si t es w t h the pract i ces at metered si t es and compensat e f or t he
di f f erence.
We recommend that al l cont r act ors be requi red to use a port abl e meter and
r epor t t he readi ngs.
Enter
the t ot al wat er vol ume used f or const r uct i on si t es on Li ne
11J
of your
Water Audi t Worksheet.
Usef ul est i mat es can be made by compar i ng water use w t h metered pool s
4
Data may be obt ai ned f romregul at ory
4
Water Qual i t y and Ot her Test i ng.
t o t est di st r i but i on syst emout put to meet publ i c heal th st andar ds and to test
Thi s water use i s def i ned as water used
met er s and new mai ns.
Est i mate water used i n water test i ng by cont act i ng operat i ons st af f to
determ ne t est i ng f requency and durati on and vol umes of water used.
w l l probabl y vary w th each user.
Li ne 11K of t he Water Audi t Worksheet .
Process Water at Treat ment Pl ants.
recycl ed) af ter f i l t er washi ng or sedi ment at i on basi n drai nage at r aw water
t reat ment pl ants.
Est i mate t hi s t ot al water use by agai n contact i ng pl ant oper at i ons st af f and
checki ng records.
Enter t he total water vol ume used f or process water at t reat ment pl ant s on Li ne+
11L of the Wat er Audi t Worksheet .
Amount s
Enter t he t ot al water vol ume used f or water qual i t y and other t est i ng on
c
Thi s i s def i ned as water l ost (not
You may di scover an unmetered use t hat does not f i t any of the previ ousl y
descr i bed categor i es.
used on Li ne 11M of t he Water Audi t Worksheet .
Now, add al l t he aut hori zed unmetered water uses ( Li nes 11A t hrough 11M) and
enter t he t ot al on Li ne
12
of t he Wat er Audi t Worksheet.
I f so, descr i be t he use and enter t he t otal water vol ume 4
4
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Task 4. Quantify Water Losses
Al l wat er t hat i s not i dent i f i ed as aut hor i zed unmet ered water i s consi dered t o
be wat er l ost f r omt he di st r i but i on system
r evenue and i s unavai l abl e f or other benef i ci al uses. To determ ne Tot al Water
Losses subt r act Tot al Author i zed Unmetered Wat er ( Li ne 12) f romCor rected Tot al
Audi t Worksheet .
Thi s water does not produce
Unmetered Water ( Li ne 10) and enter t he di f f erence on Li ne 13 of t he Water 4
Step 1. Identify Potential Water Losses
Wat er l ost f r omt he di st r i but i on systemi ncl udes underground l eaks and other
l osses Li sted bel ow
account i ng f or al l t he other l osses and subt ract i ng them f romt he Tot al Water
Losses shown on Li ne 13.
Water l osses other than l eakage can general l y be at t r i but ed to t he f ol l ow ng
causes:
The t otal amount l ost t o l eaks can be determned by
account i ng pr ocedur e er rors
i l l egal connecti ons
mal f unct i oni ng di st r i but i on syst emcont rol s
reservoi r seepage and l eakage
evaporat i on
reservoi r over f l ow
di scovered l eaks
theft
Step 2. Estimate Losses by
Type
of Loss
Thi s st ep i dent i f i es t ypes of water l osses and methods of est i mat i ng thei r vol ume.
10.
Meter readers must cope with
different meter dials and un lts of
measure.
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Accounting
_ _ _ _
rocedure Errors.
&cause
of
overlapping b i l l i n g cycles (see discussion of A d j u s t m e n t s Due t o
Water may seem t o be l o s t from the system
Meter
Reading Lag
Time,
(page-21
j ,
misread
meters,
improper-calculation methods
based on data
from meters
or other sources, computer prog raming er ro rs , or
other discrepancies.
computer process.
and
the
water
b i l l
may
be
calculated in gallons.
conversion factor would introduce error
i n
such a case.
Basically,
these
types of losses are paper mistakes that
can
be
identified by careful, step-by-step review
of
the record collecting and
For example,
the
water
meter
may be calibrated
i n
cubic-feet
Use
of an incorrect
The entire billing and accounting procedure from meter reading t o to t a l water
use and printing of billing statements should
be
reviewed.
the accounting and billing functions are scattered among several departments or
organizational units.
t ion.
sample
from
the total number of accounts.
Each
meter
route
book
should
be
checked, t o ver ify
a
sample number of accounts
from
each book (or
meter
route).
I n
some agencies
Such a fragmented arrangement can lead t o miscomnunica-
The
task of reviewing can
be
simplified by checking a representative
The
steps are:
Determine the
number
of accounts to
be
checked from each book or rodte.
Choose a random sample of accounts t o
be
checked.
Have an employee other than
the
regular
meter
reader read the ident i f ied
accounts,
or
send another employee t o accompany
the meter
reader
to v e r i f y
the meter reader's readings.
day i f possible.
being read and recorded properly and
i f the
conversion fa ct ors a r e being
used properly.
Calculate the bi l l ing of
the
identified accounts by
hand.
Compare the identified accounts for total water use
with
billed amounts.
Do
they agree?
If
not, what
i s t he
reason for the inconsistency?
If meter
book readings show a substantial difference from the accounts
t h a t were
checked, review
t h e normal b i l l i n g process step-by-step, line-by-
l ine .
Both
readings should
be
taken on t he same
The
purpose
is
t o determine
whether
the regis ter . is
Compare
the
water use volume for both
meter
readings.
Enter th e t o t a l water volume due t o accounting errors o n L i n e 14A of the Water+
Audit Worksheet.
I ll e ga l Connections. Ide ntif y ac tiv e connections
where
unauthorized water
use
is
not included
i n the
accounting and billing process.
of
water
is
usually,
but not
always, accidental rather than deliberate.
Examples include t ap s t o unmetered f i r e l i ne s
i n
a building ( i n s t a l l e r may have
been unaware that
the
l ines are reserved for
f i r e
control); a customer might
water; connections erroneously cl as si fi ed a s inac tive may in f a c t
be
i n
use;
meters
might not
be
read or
the
readings may not
be entered
i n t o
the
accounting
system.
Connections
l i s t e d
as inactive should
be
confirmed as inactive. A
well-programed computerized bi l l i ng process may di sc lo se $uch improper pr ac ti ce s.
Unauthorized use
t ap i n t o t he main or someone else's service and thus avoid paying for the
Determine whether the account i s in ac tiv e or ac tiv e. Has t h e meter been
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removed or locked i n the "offt1 position?
reader periodically check the inactive accounts to
see whether
there has been
use?
To id en ti fy i l l eg a l and unauthorized use, compare a l l act iv e and inact ive
accounts
with
a l l locations th at could receive water. One
method
is
to write
the
ident i f ica t ion
numbers
on the distribution system map and check that each
parcel has a
meter.
likely places of water use and, where possible, correlate them with account
numbers on a map.
and assessor's parcel number.
investigated.
metered.
Compare
the
number of accounts.
period?
accounts.
during the latest complete billing cycle?
and multiply by
t h e
average annual customer
water
use.
E n t e r
the total volume for illegal connections on L i n e
14B
of
the
Water Audit-
Worksheet.
Malfunctioning Di st ri bu ti on System Controls . Water
loss
may r e s u l t
from
improper app lic ati on, Xal funct ionin g and improperly set system controls.
The basic steps for determining the volume of loss remain the same: determine
t h e r a t e of loss,
the length of time during
which
the loss
occurred,
and the
frequency of
loss.
Valves are the controlling devices i n water distribution systems.
used fo r both is ola ti on
and
control functions.
manually operated, and control valves function automatically.
indicators that show the position of the valve.
t o
see whether
they a r e positioned properly.
with indicators to show
t h e i r
open
or
closed
position.
A l l
control valves
w i l l
f a i l sooner or la ter .
A s part of
the water
audi t ,
it
is important t o inspect each ins ta ll at io n th at uses automatic system cont rols
and determine whether
the
valve is working, whether it has been
set
properly
for the particular si tuation, and
whether
i ts size and design are suitable for
i t s
intended purpose.
If
neither is
t r u e , does the meter
Telephone c a l l s or v i s i t s t o th e premises may help.
A
second method
i s
t o
use
an aer ia l photograph t o iden tif y
A t h i r d
method
is
t o check each meter ident i f ica t ion number
Any parcels without an account number should
be
Some
water uses may not have an account
number
and/or may not
be
How many
existed
a t the s t a r t of the audit
Subtract those discontinued during the year. Add new or reactivated
Does the total equal the
number
of customers who have been b i l l ed
If not , to ta l the
number
of accounts
They are
Many valves have
Isolation valves are usually
Valves can also
be
re t ro f i t t ed
These can be inspected easily
A l t i t u d e
Control
Valves - Alt i tude control valves can cause a tank or
reservo ir t o sp i l l i f the valve
is
broken or set improperly.
normally set t o prevent the tank from overflowing.
The
valve i s
Pressure Relief Valves
- If t h e
pressure
relief
valve is
set
too
low
for
t h e
system's range
o
pressures, each
time the
pressure reaches
the
high
range, th e valve w i l l cause water t o s pi l l .
w i l l occur because a pressure regulating valve has been readjusted and the
pressure
relief
valve was not
reset.
Sometimes
an unnecessary spill
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Pr essur e- Reduci ng, Pr essur e- Sust ai ni ng, and Pressure- Mai nt ai ni ng Val ves -
I f
any of t hese val ves i s i mproper l y set ,
i t can cause an al t i t ude cont rol
val ve, a pressure r el i ef val ve, or a sur ge cont r ol val ve t o spi l l wat er .
Sur ge Rel i ef Val ves
-
I f t hese val ves are set t oo l ow, t hey can spi l l
water unnecessari l y as a bl ow- of f to the at mospher e, i nto a tank or dr ai n,
or
back t o the suct i on wel l of a pump.
Pump Di scharge Val ves - When t he pump di schar ge val ve f ai l s, i t act s l i ke
a check val ve t hat i s par t i al l y open and may al l ow water t o di scharge f rm
t he di st r i but i on syst emback down t he wel l .
Enter t he t ot al
l oss
f rommal f unct i oni ng di st r i but i on systemcont r ol s on Li ne+
14C on t he Water Audi t Worksheet.
Reservoi r S e e s nd Leakage.
wal l s of st or age t anks or ponds.
and out f l ow of t he r eservoi r and not i ng t he change i n stor age l evel over
aever al days.
Because water may be l eaki ng onl y at cer tai n el evat i ons of t he cont ai nment
wal l s, t he seepage (or l eakage) t est shoul d be per f ormed sever al t i mes at
successi vel y l ower sur f ace water el evat i ons. Cl ear wel l s (pol i shed wat er
st orage) are al so subj ect to seepage and shoul d be i nspected regul ar l y.
Thi s i s t he l oss f roml i ni ngs, bot t oms,
or
Water l oss i s est i mat ed by cl osi ng t he i nf l ow
Fromt hi s i nf or mat i on, t he rat e of seepage can be cal cul at ed.
Water storage tanks m ay b e subject to
overf low an d leakage.
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E n t e r the
t o t a l
loss from
reservoir seepage and leakage on Line 14D of
the
Water Audit Worksheet.
Evaporation.
l i n e d , which reduces evaporation si gn if ic an tl y. Some cl ea r wells and
Losses can be calculated by measuring
t'ne
surface area and applying
the
proper
evaporation data for your area
(see
Appendix
I
on page 123).
E n t e r t h e
total water volume l o s t to evaporation on Line l4E of the Water Audit 4
Worksheet.
Reservoir Overflow.
This
occurs most often because
the
al t i tude contro l
valve
is
faulty or missing.
discharge rate must be
determined.
t o
the
distribution system.)
example, by a stream gauge below
t h e
discharge point), the reservoir overflow
is calculated by subtracting rese rvoir outflow t o the distribution system from
the
i n f l o w
t o
the
reservoir.
deducted
f i r s t
from the reservoir inflow.
Most re se rv oir s t ha t s t o re tre at ed water ar e covered and
re re rv oi rs ar e open t o th e atmosphere and t h u s are subject to evaporation.
Both
the
periods of overflow and the overflow
(Overflow
does
not include
water
discharged
If the
discharge is not dir e ct ly measured (f or
For open reservoirs, evaporation losses should be
E n t e r
t h e t o t a l
water
volume l o s t t o re ser vo ir overflow on Line 14F
of the
Water Audit Worksheet.
Discovered Leaks.
be
measured t o determine the r a t e
of
loss and
the
total volume lost during
the
l i f e
of the leak.
under
t h e
section entitled llMeasuring and Estimating Losses from Discovered
Leaks" on page
75.
E n t e r
the t o t a l l o s s from discovered leaks on Line 14G on
the
Water Audit
Worksheet.
Theft.
hydrants.
water trucks or others who connnit acts of vandalism.
department construction permits
with
water utility temporary use billings, you
can
determine where
large amounts of water are being taken for which proper
metering and billing have not been arranged.
E n t e r the total water
volume
lost from
thef t s
on L i n e 14H on t h e Water Audit
Worksheet.
Now, add a l l
the i den t i f i ed
water losses (Lines 14A through 14H) and enter
the
total on Line 15
of
the Water Audit Worksheet.
Losses from lea ks t h a t a re discovered and repa ired can
Methods of estimating leak rates,
with
tabl es, are described
Most water t h e f t occurs when water
is taken illegally from f i r e
This
usually involves individuals
who
open t he hydrants t o
f i l l
By comparing bui ldin g
Task 5 Analyze the Water Audit Results and Consider Corrective Measures
Analysis of
the water
audi t
results
may indicate
loss
problems in the
water
distribution system.
These
could
be
faul ty metering, i l le ga l taps (such as
firelines), leaking reservoirs, or leaking mains and
services.
corrective efforts would be
cost
ef fec t ive
to
implement.
be able to est imate t he value of t h e leaking water that can
be
recovered and
the cost of recovering it.
Determine
which
To
do so,
you need t o
If the
value of the recoverable water exceeds
the
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costs, then your agency should
carry
out the appropriate leak detection and
repair program.
The following paragraphs
i l lustrate
the benefit cost procedure for a leak
detection survey.
To determine Po ten ti al Water System Leakage, su bt ra ct Tota l Ide nt i f ie d Water
Losses (Line
15)
from
Total Water Losses
( L i n e
13) .
E n t e r
t he re su l t
on
L i n e
16 of t h e Water Audit Worksheet.
Not
a l l
leaks can be detected and repaired.
Some
a r e e x t r e m e l y small; however,
estimates indicate that
75
percent of a l l potential
water
system leakage can be
recovered.
Water System Leakage
( L i n e 16)
by 0.75 and
enter
t he re su l t on
L i n e 17,
Recoverable Leakage.
L i n e
18, Cost Savings, is the cost savings that would be achieved
i f t h e
leakage was prevented.
purchase cost and variable operations and maintenance
(O&M)
costs.
costs that vary with the amount of water delivered into the distribution
sys t em
and both exclude fixed costs.
The purchase cost is
the
"Cost of Water Supply" due t o purchases of water for
the distribution system
from
another water supplie r. The amount of leakage
prevented
w i l l
reduce th e amount purchased from t ha t source. Usually, the most
effective cost reduction
w i l l resul t
from reducing
t h e
amount of water pur-
chased
or
produced from the most expensive source of supply. E n t e r the cost
per u n i t your agency pays for
i ts
most expensive water supply on Line
18A
of
the Water Audit Worksheet.
The O&M cost
is the
V a r i a b l e
O&M
Costs
saved by reducing the amount of
water
th at has t o be tr eat ed and pressurized i n the system.
water from
i ts
own
wells,
it w i l l reduce the amount of energy needed for
pumping.
NOTE:
dis tr ibu tio n system ar e t o be included.
amount of water delivered should not be included.
E n t e r
the unit costs of
~ r = ~ o p e r a t i o n ~ ~ ~ m a i n t e n a n 6 ~ - o n
i n e
18B of t he Water Audit Worksheet.
Add Costs of Water Supply (Line 18A) t o Variable O&M
Costs
( L i n e
188)
and
enter
t h e total on L i n e
19,
Total Costs Per Uni t of Recoverable Leakage.
To determine the One-Year B e n e f i t from Recoverable Leakage, multiply
Recoverable Leakage ( L i n e
17
by Total Costs
Per
U n i t
of Recoverable Leakage
(Line
1 9 ) .
Since the average lifetime of a leak
is
estimated a t two years, the to t a l
benefit from recoverable leakage
is
the value of the water saved over two
years. Therefore, t o compute the Total Benefit s from Recoverable Leakage,
multiply One-Year
Benefits
from Recoverable Leakage ( L i n e 20) by two and enter
the product on Line 21 of t he Water Audit Worksheet.
The cost of conducting a Leak Detection survey can be estimated
by
preparing a
Therefore,
calculate recoverable leakage by multiplying Potential
There
ar e two types of cost savings t o be realize d,
Both are
If the agency pumps
O nl y
O&M costs that vary with the amount of water del ivered in to the
-
ixed
-
osts that do not vary with
t h e
Enter the product on L i n e 20 of the Water Audit Worksheet.
4
4
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Leak Detection and Repair Plan.
prepare the plan.
of the Water Audit Worksheet.
The cost of leak repairs
i s
not entered. DWR conducted an economic analysis
Refer
t o
Chapter 4 for suggestions on how t o
Enter the Total Costs
of
Leak Detection
Project
on L i n e 22
c
en t i t l ed An Examination of the Benefits of Leak Detection.
found that a
major
benefi t of a leak detection
roara am
i s the reoa i r costs
The analysis-
__ _____l___l ll
_
. -
avoided (leaks repaired i n t he f utur e)
as
a r e su l t of t he program.
a r e cont inually discovered and rep air ed i n th e normal
course
of t h e u t i l i t y ' s
operations,
t h e
leaks found
i n the program would have eventually been repaired
a t some time i n the future .
detection program, the u t i l i t y w i l l avoid the expense of repairing them as they
ar e discovered acc identally.
often overlooked
when
estimates
of the savings from leak detection are made,
can often be nearly as great as
t he cost
of repairing th e
leaks
as par t of the
program.
For example, when the average l i f e of the leaks is 24
months
and the real
interest
r a t e
is
3
percent , the benefi ts
from
avoided
future
repair
costs
amount t o
94
percent
of the
cost
of
repair ing the l e aks a t t he time
of
the
program.
repairing the leaks found i n the program.
of repairs has been assumed
t o
be zero.
To
determine the Benefit
t o
Cost Ratio, div id e Total Benefits
from
Recoverable
Enter the
result
on
L i n e
23 of t he Water Audit Worksheet.
If t h e
Benefit to
Cost Ratio
i s
greater than
1.0,
then t he ben ef it s of a water
audit and leak detection survey are grea ter than th e cost s, and a leak
detection program should be performed.
Since leaks
If these leaks are repaired a s par t of a leak
These savings i n f u t u r e repair costs, which are
The
rea l cos t
of
repairing leaks in a program is generally very small.
In othe r words, t he real
cost
is only 6 percent of t he cost of
To
simplify the calculation the cost
Leakage (Line 21) by the Total Costs of Leak Detection Project ( L i n e 22).
c
REFERENCES
See
Appendixes
B
and
C
(pages 103 and 107) for guidelines on choosing the
appropriate meter
for
different appl ica t ions.
See Appendix D (page 111) for guidelines on choosing
meters
of the proper
size.
See Appendix
E
(page 115) for dir ecti ons on meter ins ta l la t ion .
with
the
equipment manufacturer f o r guidel ines .
See Appendixes
F
and G (pages 117 and 119) for meter testing procedures.
See Appendix
H
(page 121) regarding long-term
meter
surveil lance.
Also check
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CHAPTER 3. LEAK DETECTION
Visible and Nonvisible Leak s
Vis ible
____
leaks are those leaks that surface and can be seen emerging
from the
ground or pavement.
from the area where
i t i s
observed.
customers.
The
source
of t h e
lea k may be a cons iderable d is t anc e away
Many visible leaks are reported by water
Nonvisible___ Leaks include leaks that percolate into the surrounding ground and
leaks tha t enter other conveyance facilit ies such as storm drains,
sewers,
stream channels,
or
old abandoned pipes.
feet
of leakage occurs in California each year from nonvisible leaks.
DWR
estimates tha t up to 250,000 acre-
hyd rant, are easily found. und erground .
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NON-VISIBLE LE A K
HYDRANT
2. Nonvblble L u k
Examples of UndergroundLeaks
Water
w l l tak e the path
of
least resistance and may not surface.
s t a r t small and grow larger
over
time.
an average l i f e of
two
years.
underground cav it y get s l ar ge r
which
increases the po tent ia l
for
damage to
overlying property.
following paragraphs i l l u s t r at e a few of them.
City of Beverly H ills
The leak detection team detected sounds
of
leakage on numerous
services
and
used the ground microphone t o pinpoint a main leak.
main with a
pressure
of
80 pounds per square inch ( p s i ) had
a
leak
from
a 1/2-
inch hole
i n
the top of t he main.
lea k was calc ul at ed
to
be
53
gpm.
year du ra tion was 171 acre-feet. The value of th e water lost was calculated t o
be $43,000.
Most leaks
As
the age and
s ize
of
leaks increase , the
There a r e many examples
of
leaks that never surface.
Most nonvis ibl e underground l ea ks have
The
An
8-inch-diameter steel
No evidence of leakage was visible.
The
water
lost
from
t h i s l e ak fo r t he
two-
The
Placer County Water Agency
The leak survey crew detected leak sounds on a f i r e hydrant served from a 4-
inch cast iron main.
pinpointed and found in s id e an 18-inch concre te cu lver t.
from a h i l l s i d e , crossed a road, then terminated in a ravin e. Debris carried
through th e cu lver t over t he ye ar s had damaged th e 4-inch main and caused an 18-
gpm leak which drained
in to
the cu lver t.
Using t h e ground microphone, t h e leak lo ca ti on was
The main crossed
through the inside
of
Fne cu lv er t pipe. The cu lv er t pip e drained storm runoff
Over
Fne two-year pe rio d,
58
acre-
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feet valued a t $2,900 was l o s t through the leak .
City o f Petaluma
The leak detection crew detected leak noise at several services.
ground microphone, th e crew pinpointed t he leak on an abandoned galvanized
service
l i n e
that had not been shut off. The water l o s t from th e 5-gpm leak
for t h e two-year dur ati on was 16 acre -feet. The value of
the
water lost was
$4,250.
Using the
Walnut Valley Water District
The leak detection crew detected a leak sound on a hydrant and service meter.
The leak was pinpointed by using a c or rel at or and found i n a 1-inch
PV C
service
l a t e r a l near t he connection t o a 10-inch asbestos-cement AC ) main
l i n e .
Pressure i n t he l i n e was measured a t
120 psi.
service
l a t e r a l and was measured using a bucket and stopwatch a t 12 gpm.
water l o s t from th e leak f or t he two-year dur atio n was
39
acre-feet.
of
the
water
l o s t was $9,600.
The
leak was
a
s p l i t i n t he PVC
The
The value
City of Santa Clara
The leak crew det ec ted a leak sound on a 6-inch duc t il e iron pipe.
pinpointed on th e main, was a circumferent ia l break caused by set tl eme nt .
Water from th e main was leaking into an adjacent sewer a t 98 gpm.
from t he leak f or th e two-year dur atio n was 317 acre-feet.
water l o s t was $47,000.
The leak,
Water lost
The value of the
14. Circum ferential break on a 6-inch
cast-Iron main.
The
flow rate was
98 gpm.
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Value of Recoverable Leakage
Leak Rate
am
Most
agencies ar e not aware of the exi sten ce of nonvisib le lea ks and
the
value
of
detecting and repairing these leaks.
th e water system and do not generate revenue.
worth?
Table 3
shows
the
value
of
recoverable leakage based upon an average leak
l i fe-
time
of
two years
(from
"Leak Detection Productivity," by Douglas
S.
Greeley,
rates
and water costs.
Leaks are
the f i r s t
user of water on
How
much
i s
recovered leakage
Water Emergency
- - -
nd
Number 1981) and varying leak
Source of Supply
Value of Leaking Water
$/acre-foot
$/2
years
TABLE 3
VALUE O F RECOVERABLE LEAKAGE
1/11
1 4
114
1 4
1
1
1
1
5
5
5
5
25
25
25
25
100
100
100
100
50
100
250
500
50
100
250
500
50
100
250
500
50
100
250
500
50
100
250
500
40
81
202
404
162
324
808
1,615
R10
..
1,610
4,038
8;075
4.050
8;100
20,188
40,375
16,150
80,750
161,500
32 300
500 50 80,750
500 100 161,500
500 250 403,750
500 500 807,500
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An Overview
of
Leak Detection M ethods
Water Audit
Thi s method i s an ef f i ci ent way f or det ermni ng t he t ot al vol ume and val ue of
wat er t hat i s l eaki ng f rom
a
wat er di st r i but i on system The water audi t i s
a
subt r act i ve process whi ch i ncl udes quant i f yi ng t ot al water i nt o t he syst em
wat er sal es, unmetered uses, wat er l osses, and r ecover abl e l eakage.
audi t al so i ncl udes
a
benef i t : cost anal ysi s f or r ecover i ng pot ent i al l eakage.
The f i nal part of t he wat er audi t i s t he preparat i on of a Leak Detect i on and
Repai r Pl an whi ch out l i nes t he equi pment , t ype of cr ew, method of surveyi ng and
pi npoi nt i ng l eaks,
and the cost s i nvol ved. Exampl e 19 i n Chapter
4
( page
59)
i l l ustr ates
a
Leak Detect i on and Repai r Pl an.
Audible Leak Detection
Thi s method uses el ect roni c l i st eni ng equi pment to det ect the sounds of
l eakage.
t he pi pe
wal l
and to t he surroundi ng soi l area. Thi s energy creates sound
waves i n t he audi bl e r ange whi ch can be sensed and ampl i f i ed by el ectroni c
t r ansducers or , i n some cases, by si mpl e mechani cal devi ces.
are then eval uat ed by an i ndi vi dual t rai ned i n l eak detect i on who can determ ne
t he exact l ocat i on of t he l eak.
i ni t i al l i steni ng survey of t he ent i r e di st r i but i on systemand r ecor ds al l
suspect sounds.
are pi npoi nted.
Ther e are t hr ee t ypi cal l eak sounds.
The water
Pressur i zed water t hat i s f orced out t hrough a l eak l oses energy t o
The sound waves
Thi s i ndi vi dual , t he oper at or , conducts an
I f t hese sounds ar e heard agai n when rechecked l ater , l eaks
The f i r st sound i s normal l y i n t he
15.
Valves are excellent co ntact points
for
sounds
of
leakage.
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500 to
800
her t z (Hz)
range. I t usual l y or i gi nat es as an or i f i ce- pi pe
vi brat i on phenomenon and i s t ransmt ted al ong t he pi pe wal l -- i n sane
i nst ances
a
consi der abl e di st ance f romt he actual poi nt of l eakage.
i dent i f i cat i on of t hi s sound by systemat i c t est i ng of val ves, hydrant s,
and
curb val ves w l l f requent l y l ocat e potent i al l eaks.
Both the second and thi rd sounds are i n t he
20
t o
250
Hz range.
sound i s caused by t he i mpact of water upon soi l i n t he area of t he l eak.
thi rd sound resembl es t he sound of a f ountai n.
t i on, usual l y i n a cavi t y i n t he soi l near t he l eak.
t he pi pe wal l , t he t ravel di st ance of t hese t wo sounds i s l i mted t o t he
i mmedi at e area of t he l eak, and, . f or thi s r eason,
t hese t wo sounds ar e very
i mport ant i n pi npoi nt i ng the l eak for excavat i on and repai r .
The
The second
The
I t i s caused by water ci r cul a-
Unl i ke t he vi brat i on on
There are a number of f actors that i nf l uence l eak sounds, and t hese f actors
must be taken i nt o consi derat i on.
o
I_
ressure
-
I t i s usual l y necessary t o have
15
psi
or
more water pressure
f or soni c l eak detecti on.
o P&
_I____
at er i al and Pi pe Si ze - Because metal l i c pi pe i s
a
much better
sound conductor than nonmet al l i c pi pe, a cl oser test i nterval i s requi red
when searchi ng for l eaks on nonmetal l i c pi pe.
used, however, on pi pe and f i t t i ngs of any mater i al .
Sol-
-
The t ype of soi l great l y i nf l uences the amount of sound
t ransmt ted to t he surf ace.
normal l y a good conductor of sound; cl ay i s a poor conductor.
Surf ace-
-
The type of sur f ace on whi ch t he soundi ng i nst rument i s
pl aced i s anot her f actor .
asphal t and concr ete are good r esonators and gi ve a uni f orm soundi ng sur f ace.
They i ncl ude:
Soni c t echni ques can be
o
Empi r i cal observat i on i ndi cat es that sand i s
o
Sod tends t o i nsul at e and muf f l e sounds, whi l e
Zone Flow Measurements
Thi s method can reasonabl y be under t aken as an extensi on of t he water audi t or
i n some cases di rect l y as a l eak detect i on method.
whether a sector or zone77of a water system i s suf f er i ng maj or l eakage.
ef f ect i vel y conduct
a
zone f l ow measurement
a
ut i l i t y must mai ntai n good maps,
have val ves l ocat ed at zone cont rol poi nt s, and provi de a tap i n t he mai n f or
t he recordi ng pi totmeter .
Zone measurement s are most ef f ect i ve i n l arge resi dent i al or rural sect i ons,
l ess so i n commerci al or i ndust r i al areas. The w nter mont hs are t he best t i me
f or zone measurement s as they are l ess af f ected by out si de water use ( l awn
t emperature shoul d be avoi ded, si nce cust omers may l eave water runni ng t o avoi d
water l i ne f reeze-up. Twent y- f our - hour r ecordi ngs are recommended and dayt i me
f l ows are compared w t h ni ght t i me f l ows.
to ni ght t i me reservoi r f i l l i ng or unusual water usage such as ni ght i r r i gat i on
or a commerci al use such as a l aundry operat i on.
mni mum usage.
I t s purpose i s t o det er m ne
To
wateri ng
and
i r r i gat i on) . However , ni ght s that are subj ect to extreme f reezi ng
Water ut i l i t y staf f shoul d be al er t
Al l owances are made for
Fl ows great er than these mni mum f l ow rat es i ndi cat e l eakage.
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Sections
of
t he water system are isolated and valves are closed to permit water
flow from a s in gle l ine .
the flow r a t e
i s
unacceptably high and warrants ad di ti on al in ve st ig at io n and
correction.
valving in
the
area of in te res t .
Another
form
of zone measurement
is
the
storage tank method.
and the the en ti re zone is supplied by st or ag e tanks.
read for volume and
a11
the customer meters i n the zone are read. During t h a t
time period, t h e stora ge tanks are not replenished.
such
as
a
week,
the procedure is repeated.
difference between the water supplied
t o the
system from
the
storage tanks and
the sum of
the
meter readings.
meters must have been previously determined.
The usage r a t e can be estimated
t o
determine
whether
Zones can
be
further subdivided depending upon
the
exis t ing
This
type
of
zone
measurement can
be
used in pressure zones
where there
ar e only
a
f e w customers
Each s to ra ge tank i s
Rfter a period of time,
The
pot ent ial leakage
is the
With
t h i s
method, the accuracy of customer
Normal Course of Operation
This
method involves discovering leaks acc identa l ly i n
the
normal course of
operations and maintenance.
may be discovered during t he exercising of valves.
opportunity
to
check f o r v i s i b l e meter
box
leaks when reading
the meters.
For example, in a valve exercising program leaks
Meter readers have
the
Leaks You Can Expect to Find
Main Line Leaks
Main l i n e lea ks range
from
a
low
of
1
gpm
t o
over
1,000
gpm.
corrosion usually
s t a r t
out small but can grow
t o
very large leaks.
S p l i t s can occur due
t o
excessive pressure, improper in st al la ti on settlem ent,
and overloading.
Leaks due
t o
16.
Excavatlng a
53
gp m leak on an old
st eel main.
17.
Sewlc e laterals are com mon In'metall lc pipes.
This leak was m easured at 2 gpm.
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Jo in t lea ks can occur due t o corrosion, improper in st al la ti on , improper
materials, or overloading.
Service Line
Leaks
Service l i n e leaks range from a low of 0.5 gpm t o over
15
gpm.
lea ks a re caused by the same fa c tors a s main
l i n e
leaks.
Service
l i n e
Residential Meter Box Leaks
Leaks within the vicinity of the
meter
box range from a low of a fraction
of a gpm t o a high of
10
gpm.
Common examples include l eaks due to:
o
loose spud n u t s on ei ther s ide
of
the meter
o
loose packing nuts
o damaged or broken angle stops
o broken or damaged couplings
o
broken
meters
o
damaged or broken
meter
yokes
18.
Leaks from meter boxes are some-
tim es visib le. Here, leak detection
equipm ent determines whether stand-
ing water is runo ff or leakage.
Residential Customer Leaks
Leaks on the residential customer side
of t h e
sys tem range from a low of a
fracti on of a gpm to a high of 15 gpm.
o
holes or breaks in customer
service
l ines
o inefficient hose bib or shutoff valves
o holes or breaks
i n
interior plumbing l ines
o leakage ins ide plumbing fi xt ur es ( t o i l e t
f i x t u r e
leaks are common)
Common examples include:
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Valve
Leaks
Leaks i n d is tr ib ut io n system valves range f r m a low
of
a frac ti on of a gpm t o
a high of
500
gpm.
broken valves.
Leaks may s t a r t
i n
system cont ro ls such a s pressure-reducing valves , pressure-
sustaining valves, pressure-relief valves, a lt it ud e control valves, blowoffs,
air-release valves, and others.
Common
examples include leaks due t o l oose packing and
Miscellaneous
Leaks
Breaks from excessive pressure, settlement, overloading, improper installation,
improper mater ials, and improper operat ion may occur.
19.
improp er repair
of
hydrant lateral
caused this leak to occur mo nths alter
inlt lai repairs.
20.
Transmission m alniine leak un der this
reservoir was detected by introducing
pressu rlzad air Into the main.
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CHAPTER 4. CONDUCTING A LEAK DETECTION SURVEY
Leak det ect i on
i s
a process of el i mnat i on and di scovery.
el i mnate t he cont act poi nt s where l eak sounds are not heard and di scover t he
cont act poi nt s wher e l eaks can be heard.
The goal i s t o
Preparing for the Leak Detection Survey
Pr eS ur ve y Review
Pr i or to conduct i ng a l eak detect i on sur vey, you shoul d revi ew t he speci f i cs of
your di st r i but i on system
o
o mai ns and ser vi ces -- t ypes of pi pe, ages, di amet er s, j oi nt s, i nstal l at i on
The fol l ow ng i nf ormat i on i s i mport ant to revi ew:
resul t s of t he water audi t
--
How much wat er i s l ost f romthe system?
met hods, i nspect i ons, l eak hi st ori es, and operat i ng pressures.
types of i nst al l at i ons, meter shut of f s, coupl i ngs, and meter readi ng
f requency.
o
val ves -- l ocat i ons, t ypes of val ves, l ef t or r i ght handed, number of turns
t o exerci se val ves, and how of t en exerci sed.
o hydrant s -- t ypes, si zes, l ocat i ons, f l ushi ng f r equenci es, and unmetered
usage.
pressure- reduci ng val ves, pressure- sustai ni ng val ves, pressure- rel i ef val ves
-- l ocat i ons and how of t en they are exerci sed.
o
bl owof f s and ai r r el ease val ves
--
l ocati ons and how of t en they are
exerci sed.
o di st r i but i on syst emmaps
--
What i s shown on maps, how current i s t he
i nf ormat i on, and how of t en i s t he i nf ormat i on updated?
o meters and meter box assembl i es -- t ypes, br ands, and si zes of met er s, ages,
o
Leak Detection Equipment
Pr ovi de leaic detect i on equi pment f or cr ew members i ncl udi ng soni c l i st eni ng
equi pnent w t h a hi gh f requency l i st eni ng probe and a l ow f requency ground
mcrophone f or pi npoi nt i ng l eaks,
manuf acturers i s i n Appendi x
J
( page 125).
Provi de saf ety equi pment f or cr ew members i ncl udi ng:
o
saf ety vest s
o
t raf f i c cones
o barr i cades
A
l i st of l eak det ect i on equi pment
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Pr ovi de t ool s t o measure f l ow r at es i ncl udi ng a:
o
st opwatch
o
bucket
o measuri ng cup
o
pressure gauge
o measur i ng t ape or a rul er
Provi de worki ng t ool s, such as:
o meter box l i d l i f t er s
o val ve cover l i f t er s
o
val ve keys
o curb st op keys
o smal l bai l i ng cans or smal l manual pumps
o chal k ( keel ) or spray pai nt
o pi pe l ocat or s
o wrenches f or t i ght eni ng meter spud nut s
Selecting Team Members
When sel ect i ng t eammembers consi der t he f ol l ow ng qual i t i es:
o keen sense of hear i ng
o abi l i t y to di scern di f f erent sounds
o
f am l i ar i t y w t h water met er s and the di st r i but i on system
o sense of r esponsi bi l i t y
o
abi l i t y t o est i mat e l eak f l ows
o abi l i t y to compl et e l eak f or ms
o
abi l i t y t o work on thei r own
Planning the Survey
When pl anni ng how the l eak survey w l l be conducted consi der t he f ol l ow ng:
o What t ype of noi se probl ems exi st w t hi n t he system?
o '&a ef f ect w l l t raf f i c have on t he survey?
o What t ype of prot ect i on i s requi red for t he l eak crew?
o
*&at t i me of day or ni ght w l l be most ef f ect i ve to conduct t he l i st eni ng
survey?
o
What t i me w l l be most ef f ect i ve t o pi npoi nt suspected l eaks?
o
I s
t he cr ew a compat i bl e group t hat w l l work t ogether?
o How w l l t he crew s t asks be di vi ded?
o
What i s t he most ef f ect i ve r out e t o f ol l ow i n t he i ni t i al l i steni ng survey?
o Whi ch ar e t he most ef f ect i ve l eak survey and pi npoi nt i ng f orms and how are
t hese records to be compl eted?
o
How w l l l eak detect i on cr ews communi cate and work w t h repai r cr ews to
ensure ef f ect i veness and r esol ve dry hol es?
Leak Detection & Repair Plan
Prepare a Leak Detecti on and Repai r Pl an.
pages;
a
sampl e pl an i s i ncl uded
i n
Appendi x A.
Appendi x
'L
( page
127).
A pl an
i s
shown on the f ol l ow ng
Bl ank f or m are l ocat ed i n
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EXAMPLE
19
LEAK DETECTION AND REPAIR PLA N
WORKSHEET
Name
of
Agency:
XYZ
County
_ I_
a t e r D i s t r i c t
-
Date: 7/18/85
-
A. Area to be Surveyed
1.
2.
3.
4.
Using the
results of
t h e water audit, show
on
a map which areas
in the dis t r ibut i on system w i l l be surveyed.
are as have th e higher pot ent ial fo r recoverable leakage.
Describe each area under B-2. (Items
t o
consider include records
of
previous leak s, type of pipe, age of pipe, s o i l conditions,
high pressures, ground sett lem ent , and improper i ns ta ll at io n
procedures. )
Total miles of main to be surveyed:
I_
46
.
I f
less
than the
to ta l system i s being surveyed, th e calc ula tio ns fo r th e
benefit :cost r a t io must ref le c t t he reduction.
the miles
of
main, include the t o t a l l ength
of
pipe and exclude
serv ice lines.)
Average number
of miles of
main surveyed per day:
In di cat e which
(When calculating
2.0
Explain
i f more
than
3 miles
per day are surveyed.
survey
crew
can survey about two
miles
of main per day.
consider include d is tan ces between
services,
t r a f f i c and sa fe ty
conditions, and number of listening contact points.)
(The average
Items t o
Number of working days needed t o complete survey:
73
(Divide Line 2 by Line 3.)
B. Procedures an d Equipment
1.
Describe the equipment and procedure you
w i l l
use t o detect leaks.
Experience has shown t h a t t he be st r e s u l t s have been obtained by
l i s t en ing f o r l e aks a t a l l system
I_
ontact points
(such
a s water
meters, valves, hydrants, and blowoffs).
Purchase H e a t h S o x i- K it . A tt e n d Manufacturers Seminars and_----
DWR Train ing .
-
o n d u c t i n i t i a l_ i s t e n i n g su r ve y on-l l c on ta c t
_-__
_- ___
o i n t s .
59
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EXAMPLE 19 (ant . )
LEAK DETECTION
&
REPAIR PLAN WORKSHEET
2.
3.
4.
5.
6 .
Describe why the areas noted on the map (A-1) have tine greatest
potential for recovering leakage.
Ar ea 1 - Downt own - ol d duct i l e i r on mai ns
Ar ea 2 - St eel mai ns over 40 years ol d
Ar ea 3 - R~~~kder of wt * m
If you w i l l not be l is ten ing for leaks a t a l l system contact
points, describe your plan for effectively detecting leaks.
Not aDDl i Cabl e - crew wi l l 1
Describe
the
equipment and procedure you w i l l use to pinpoint the
exact locati on of tn e detected leaks.
W l l use l ow f r equency gr ound m cr ophone to l i st en over
pavement sur f aces. Consul t ant s cor r el at or wi l l be used i n
di f f i cul t s i t uat i ons.
Describe how the leak detection team and the leak repair crew
w i l l work together. How will they resolve t he problem of dry
holes.
The l eak det ect i on cr ew and t he r eDai r cr ew wi l l i oi nt l y
evcavat e al l l eaks
f o r
t he f i r s t
3
weeks and r esol ve and dry
hol es t her eaf t er .
Describe
the
methods you w i l l use t o determine the flow ra te s fo r
excavated leaks of various sizes.
Bucket and st opwat ch met hod wi l l be used on smal l l eaks.
l ar ger l eaks t he di ameter
of
t he hol e and t he pr essur e wi l l be
measured and used i n t he Gr eel ey f or mul a as shown i n t he Gui debook.
For
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EXAMPLE
19
(cont.)
LEAK DETECTION & REPAIR PLAN W ORKSHEET
C. Staffing
1. How many agency st af f w l l be used? 2
St af f Cost s I ncl udi ng Wages and Benef i t s:
Person 1 $/ hour
17 .19
-
$/ day 137.52
Person 2 $/ hour
12 .50 $/ day 100.00
TOTAL $/hour
29 .69
-_
$/ day 237.52
2. H o w many consul t ant st af f w l l be used? 1
Cost of Consul t ant Staf f :
Per son 1 $/ hour 31 .25 $/ day 2 5 0 . 0 0
Person 2 $/ hour
-
$/ day 0
TOTAL $/hour 31 .25 I/ day -____50.00
D. Leak Detection Survey Costs
Leak Detect i on Surveys: $/ day # Days Cost
1.
Agency Crew Cost s
237.5 2 73 $17,340
$ 3,750
. Consul t ant Crew Cost s 2 5 0 . 0 0
175
___I _
5
3. Vehi cl e Cost s 2.40 73
4. Other
d
-
$- --
5. TOTAL Survey Cost s $21,265
E. Leak Detection Budget
1.
2. Leak Det ect i on Team Trai ni ng
3. Leak Detect i on Survey Cost s
4. TOTAL Leak Detect i on Costs
Cost of Leak Detect i on Equi pment
$
2,550
$-
400
$21,265
$24,215
-___
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EXAMPLE
19
(cont.)
LEAK DETECTION & REPAIR PLAN WORKSH EET
E
Leak Survey and Repair Schedule
I ndi cat e r eal i st i c, pract i cal dates.
1. When w l l t he l eak survey begi n? August 1, 1986
2. When w l l t he l eak survey be compl eted? December 15, 1985
3. When w l l l eak repai r s begi n? August 15, 1985
4. When w l l l eak repai r s be compl eted? January 10, 1986
Prepared
by:
C. M. Biggs 7 / 1 8 / 8 5
Name Dat e
Ti t l e
Mlnl”=r
Team Training
Trai n t eammembers pri or t o conduct i ng a l eak detect i on survey.
opt i ons ar e avai l abl e:
o
Attend manuf act urers’ t rai ni ng semnars.
o
o
o
o
The f ol l ow ng
Have manuf act urers i ncl ude on- the- j ob t rai ni ng when purchasi ng equi pment .
Obtai n on- the- j ob t rai ni ng f romother agenci es w th exi st i ng programs.
Obtai n t rai ni ng f rom
a
consul tant .
Obtai n t rai ni ng f romt he DWR Di st r i ct i n
your
area.
22.
On-the-job training
for
ieak-
detection crews b uilds con fidence.
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Equipment Tuneup
Leak detect i on equi pment must be operati ng properl y for
a
successf ul survey.
Pr i or t o conducti ng t he sur vey, l eak detecti on st af f shoul d f am l i ar i ze them
sel ves w th t he equi pment .
i nstr uct i ons.
o
Do
t he bat t er i es need t o be charged or repl aced? (Br i ng extra bat ter i es. )
o Are al l el ect r i cal and physi cal connect i ons ti ght ?
o Are al l cont r ol s worki ng proper l y?
o Check to see i f you can hear t he basi c l eak sound by t est i ng t he equi pment
on
a
hose bi b w t h water runni ng and t hen w th no water runni ng.
Consul t t he i nst ruct i on manual and revi ew t he
Check t he equi pment f or t he f ol l ow ng i tems:
Pr act i ce w t h t he equi pment you w l l be usi ng t o det ect l eaks.
l i st eni ng and di scerni ng t he di f f er ences i n sounds by det ermni ng the f ol l ow ng
f actor s
:
o
t he uni que background sound of your i nst rument
o
what a qui et sound i s ( when no l eak or water use i s present )
o
what water use sounds l i ke by openi ng a hose bi b on
a
customer ' s servi ce l i ne
o
what t he sound i s when a f aucet i s dr i ppi ng
o
what the sound i s when spri nkl ers are i n use i n t he area
o
what the sound i s when the meter i s turni ng
Pr act i ce
Leak D etection Procedures
Initial L istening Survey
The obj ect i ve of t he i ni t i al l i steni ng survey i s to l i sten f or l eak sounds on
al l contact poi nt s i n t he di st r i but i on system
m cr ophone and l i st en f or l eak sounds on al l wat er met er s, val ves, hydr ant s,
bl owof f s, ai r r el ease val ves,
and other contact poi nts. Not e the addr ess of
al l l ocat i ons wher e water use, meter sounds, or possi bl e l eak sounds exi st .
Thi s par t of t he survey i s t he i ni t i al search through each area of t he system
and can be conduct ed qui ckl y.
Use
t he hi gh- f requency cont act
23. Listening o n all valves and ail other
contact points In the dlstr ibu tlon
sys-
tem
Is
imp ortant to an effective sur-
vey.
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Nonmet al l i c mai ns r equi r e ext ra ef f ort i n l i st eni ng surveys. I t may be
necessary t o l i st en over t he mai n w th the ground mcrophone t o det ect l eak
sounds. Thi s i s dependent on syst empressure, pi pe di ameter , and equi pment
sensi t i vi ty.
nonmet al l i c mai ns
(
Asbest os/ Concret e or pl ast i c), use t he ground m cr ophone
and l i st en over t he mai n. Have
a
teammember turn on
a
hose bi b at t he
cust omer ‘ s servi ce.
sound
of
water escapi ng f romt he hose
bi b.
mcrophone and l i st en over t he mai n.
greater than t he di st ance that t he sound t r avel s al ong the mai n, t hen you
shoul d use the ground mcr ophone and l i st en over t he mai n at appropr i ate
i nt er val s
(10
t o 25 or
50
feet).
Problems Encountered with the Listening Pracedures
To det er m ne whether t he systemr equi r es l i steni ng over
Determ ne over what di st ance al ong the mai n you hear t he
You may not have t o use t he ground
I f t he di st ance bet ween contact poi nt s i s
Sounds f rom- Cust omer Use I nsi de a Dwel l i ng.
Exampl es of such sounds are:
s ho wKt oi l et s , pumps, met er s, and conversat i ons.
Sounds f romOut si de
a
Dwel l i ng.
w nd and rai n, st r eet craf f i c, i nt er f er ence f rompower l i nes or t r ansf or mer s,
r adi o br oadcast i ng, or l awn wat er i ng,
Some of t hese sounds come f romai r cr af t ,
--ounds f romWater Noi ses.
val ves, or t urbul ence.
These sounds usual l y come f romadj acent l eaks,
Other Probl ems.
equi pment ( l oose el ect r i cal connecti ons) , :
Some other probl ems that may be encountered are f aul t y
i mproper t r ai ni ng, or systempressure
l ess t han 15 Psi .
WATER
ADDRESS
CITY
DATE
TIME
East Bay Municipal Utility District is “listening” to
its
water mains and service connections with electronic leak
detection equipment. As part of this survey, customer
house plumbing systems are “listened to” at the meter.
The detectors have picked up the sound of running water
on your plumbing system, which could mean that you
have leaks in your plumbing. In order to conserve water
and to prevent high water bills, please check your house
for leaks or running water, using the checklist on the
reverse side of this card.
c-93 11175
3. Doorhanger notifying residential customer of p ossib le
plum bing leaks.
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Relistening to Suspect Sounds
Return
t o each of
the
locations noted
i n
the
in i t i a l l i s ten ing survey.
the high frequency contact microphone, relisten fo r t h e sounds you heard
e a r l i e r . I f
the
location
is
quie t ,
i t is
not a leak.
If
you s t i l l hear
sounds,
i s t h e
meter running?
Using
If
you s t i l l hear
sounds
when there
is no
water
____
exists. _____
his leak mus t
bT
24.
Re-listening to suspect sounds heaid
on the init ial survey confirms the
sound of a leak or a water-use
sound.
Pinpointing Leaks
The
objectives of pinpointing leaks are ( 1 ) t o determine whether the leak sound
i s leakage, water use, or sane other noise; and
(2) f
it is a leak sound,
determine the lea k' s exact location.
Return t o th e suspected l ocat ion and again l i s t e n f or t he sound.
leak sound?
a l l resources available--naked ea rs , eyes, a sonic amplifier--and walk around
the
area.
pressure reducing valve or electrical transformer.
Review detailed distribution
system
maps and lo ca te pressure reducers,
forgotten valves, or other system apparatus which might make the suspect
sound.
located any suspicious cu lp ri ts , can they
be i d en t i f i ed
and isolated?
example, a customer pressure-reducing valve can
be
isolated by shutting off
the
customer service and bleeding the pressure off
the
system by opening
t h e
customer's hose
bib.
Be sure_ o check with the customer before shutting off
the service
Do
you hear a
If you s t i l l hear a suspect sound,
i t
might not
be
a leak.
The
sound may be from something ot her than a leak, such as a
Use
Check the immediate vicinity and look for suspicious causes. If you
For
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25. Listening on both sides
of
the meter
for the loud est sou nd determines
whether a leak is on th e ut i l i ty “ s ide”
or
the customer’s “ side.”
If the leak noise is heard on a water meter, determine
i f
the sound
is
louder
on
the
customer
s ide or
the agency
s ide of
the meter. Look for obvious signs
of customer use.
may
be
heard turning even i f
t h e
meter hand is not moving.
indicator for movement.
ca re fu l ly
for
leak sounds on both sides
of the meter. If
you are s t i l l
uncertain, you can contact the customer and notify him that you w i l l be
shut t ing
off
h i s se rv ice for a few minutes.
off
system pre ssu re from
the
customer by opening the
hose
bib.
sound quits,
the
leak
is
within
the
meter box, on
the
customer’s servi ce li ne ,
or i n t h e dwelling.
agency side of
the
meter.
If a leak is determined to
be
on the customer
s i d e
of the meter, leave a
doorhanger (such a s tine one shown
below)
notifying
t h e
customer that they might
have a leak in their servi ce l i ne , in te ri or plumbing, or water using fixtures.
Perhaps sprinklers are operating.
I n
t h i s
case , t h e meter
Check
the meter
The leak may be i n the area of the
meter
box.
Listen
Close
the
angle stop and bleed
If t h e leak
If the noise continues,
i t indicates
the
leak i s on
the
26. A
doorhanger notif ies a customer that
leakage s suspected on his side
of
th e meter.
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If the leak is on
the
main or the se rv i ce l i ne , t h e leak sound may
be
detect-
ab le on adjacent s erv ice meters, valves, or hydrants.
L i s t e n for
sounds of
leakage on serv ice s adjacent t o
t h e
suspected meter and determine where t he
sound is
t h e
loudest.
Pinpointing the exact location can be accomplished by
using
the
ground microphone method
or
using
the
corre la tor method.
Ground Microphone
_I_
ethod.
the locat ion of the loudest leak sound over the main or se rv ice l i n e (p ipe).
The object ive of using t h i s
method i s
t o f ind
-
The f i rs t
s t ep is t o determine
electronic pipe
locator can
be
Precisely mark the location of
Locate other nearby pipes from
the exact location
of the
main
or
se rv ice. An
used t o lo ca te th e buried main or se rv i ce l i ne .
t he
main
or
service line on the pavement.
which
the sound might be coming.
27.
Effectlve plnpoln tlng requlres the use
of p ipe locaters to determ lne the exact
locatlon of undergrou nd plpes.
Ground microphones a r e either monophonic or stereophonic, depending upon t h e
manufacturer.
i n t ens i ty between two microphones.
microphone.
The
s t e reo models have the capabi l i ty t o discern differences in
However,
most
models have only one
28.
If he location of pipes Is known, a
ground mlcrophone wl l l help pinpoint
the locatlon
of
leaks.
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When usi ng the ground m cr ophone f or pi npoi nt i ng, r emember t o set t he vol ume
rel at i vel y l ow at the begi nni ng, so l oud sounds w l l not be uncomor tabl e.
Keep t he vol ume adj ust ment at t he same l evel t hroughout each pi npoi nt i ng
sequence.
saf et y, then resurvey t he poi nt s t o l ocat e t he l oudest l eakage sounds.
Use the ground mcrophone and l i st en f or l eak sounds every
5
t o
10
f eet and
wr i t e not es on the sound i ntensi t i es.
t he meter r eadi ngs down.
of t he l eak. Be car ef ul NOT t o change t he sett i ng of t he vol ume or other
cont rol s dur i ng thi s process. Wher e possi bl e, avoi d compar i ng sounds f rom
poi nt s w t h di f f er ent sur f ace and compact i on charact er i st i cs. I f t hi s i s
unavoi dabl e, make al l owance f or t'ne fact that t he same l eak sound w l l be
qui et er f rom
a
l oosel y compact ed sur f ace t han
a
dense one.
The ground m cr ophone process shoul d be repeated t o ver i f y t he l eak l ocat i on.
I f uncom or t abl y l oud sounds are hear d, r educe t he vol ume f or your
I f t he equi pment has
a
met er , wr i t e
The st rongest si gnal usual l y i ndi cates the l ocat i on
29.
Geophones enable l istening In stereo.
Correl ator Method.
used t o pi npoi nt l eaks whi ch usual l y i ncl udes t he fol l ow ng i tems:
o
o
o
o
a m crocomput er
o
o
a
cat hode ray tube ( CRT) vi deo di spl ay
o
o
A cor rel at or i s a package of el ect roni c equi pment
t r ansducers ( t wo or more) whi ch pi ck up the noi se f romt he pi pe and conver t
i t i nto an el ect roni c si gnal
t wo set s of cabl es or r adi o t ransmt t ers/ recei vers t o car ry t he el ectr oni c
si gnal f rom the t r ansducer s to t he correl ator
ampl i f i ers and a correl at or whi ch compare t he si gnal s recei ved f romt wo or
more si gnal sour ces
a speaker (and headphones) t o recreat e t he l eak sound f or t he operator
a paper t ape pr i nt er , on some model s, t o provi de a permanent wr i t ten di spl ay
of t he l eak wave f orm and t he di st ance of t he l eak f romt he cont act poi nts
a
power suppl y ( of ten a 12- vol t aut omobi l e bat tery)
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CORRELATOR METHOD
Som e com elators have a pap er tape, along with a
CRT.
for permanent records
of
a leak.
Prospect i ve users of cor r el at or s shoul d be advi sed t hat cor rel at or s are compl ex
el ectroni c equi pment that r equi r e consi derabl e t rai ni ng f or successf ul use.
Corr el ator s are not desi gned t o be car r i ed by hand.
pounds and need an el ect r i c power suppl y.
some model s may be used for soni c l eak detect i on when handl ed caref ul l y.
They wei gh f rom25 t o 50
The t ransducers/ t ransmt t er uni t s of
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***
RUN
***
tmrmsl
C ~ I
m GP 1.28
3.7
B C I P
75-1.28
15.2
1 P 1 . 2 8 5 . 6
4
R
6:
7.77
Td= -7.6 Cmsl
R:
16.73 Cml
01
6
5 ,
vz:
2
MEM.
31. TLplcal paper tape outp ut of l eak ioca-
t ion. The spike on the chart locates
the
posl t lon
of
the l eak between ¶he
blue an d red transducers.
D A T E
NO.
After
confirming that the ame leak sound i s
s t i l l
present and can be detected
from _.
wo
separ ate contact points, the cor rela tor may be
u s e d .
The
pipe locations and configurations must be determined even more accurately
than
they were i n the
sonic equipment method.
__
etween the
contact
points
must be ca re fu ll y measured in the
f i e l d
(including
th e depth from surface t o main) and t h i s information i s
fed
i n to t h e computer.
Pipe s i ze and materia l type is al so input t o th e computer.
Two elect roni call y amplified transducers a re attached t o separate contact
points
on
each
s ide
of
the
detected leak.
The
distance
-
long the pipe
The operator must take great care
t h a t
t h e
transducers are identified
with
the co rr ec t color-coded contact
points.
Otherwise, t he
distance t o the leak
w i l l be
measured from t h e wrong
contact point resulting
i n
a dry hole.
32.
A
transducer detects the leak sound,
which is transm itted b y a po rtable
transm itter to the correlator. Pinpoint-
in g a leak requires
two
l istening
points that span th e leak.
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The cor rel at or computor senses the l eak noi se, t hen cal cul ates t he di st ance
f romt he l eak t o each t ransducer .
di spl ay or pr i nt ed on paper tape.
The operator t hen measures the i ndi cated di st ance f romone of t he cont act
poi nt s to f i nd t he l eak l ocat i on. A wort hwhi l e check i s t o r emeasure the
di st ances f rombot h cont act poi nt s t o be sure t he i ni t i al measurements are
corr ect . )
Af ter pi npoi nt i ng t he l eak usi ng ei ther met hod, mark t he pavement above t he
exact l ocat i on of t he l eak.
turn i n work or ders f or repai r .
Pr obe Method.
t wo previ ous met hods i s t o dr i l l a smal l hol e t hrough the pavement over t he
suspected l eak l ocat i on.
t ake car e not t o damage t he pi pe.
a
met al rod w t h
a
T handl e caref ul l y i nto t he hol e and use the hi gh-
f requency soni c m cr ophone to l i st en agai n f or t he sound of l eakage.
t o f i r st check f or other ut i l i t i es. Addi t i onal hol es may be dr i l l ed as
necessary.
The r esul t s ar e di spl ayed on the CRT vi deo
Log al l i nf ormat i on on the l eak detect i on l og and
An addi t i onal pr ocedur e t o f ol l ow when usi ng ei ther of t he
When dr i l l i ng hol es i n t he pavement over t he mai n,
Water may surf ace t hrough t he hol e.
I nser t
Remember
33. In unpaved areas, a probe can b e
us ed as an extension t o l is tening
direct ly o n
the
burled pipe.
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To assure that you w i l l not be a f fec ti n g o th er u t i l i t i e s ,
before
digging,
contact Underground Service Alert (USA), a locat ion service, at :
o
800)422-4133 for
t he
Southern California counties
of
Imperial, Inyo, Los
Angeles, Orange, Riverside, San Bernardino, San Diego, Santa Barbara and
Ventura.
(800) 642-2444 fo r a l l other Californi a counties plus
the
State of Nevada.
Excavating the Leak.
th e repa ir crew should work toge ther t o uncover th e leak.
the survey crew can re li st en t o
the
sound and assist the repair crew in
locat ing
the
leak.
t he
pipe or a
few
inches away and no sign of dampness or water
is
v i s ib l e .
working together, both the survey and repair
crews
can share knowledge and
experience that make locat ing
the
leak easier.
When excavating the leak, both the survey crew and
If
the
hole is d r y ,
Leaks may
be
missed because the leak is on the bottom of
By
34.
Uncovering leaks requires caref
excavation to avoid oth er pipes,
util it ies,
or
both.
u l
other
,
2
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Leak Detecti on-.
The f ol l ow ng t i ps may be of assi st ance when
conduct i ng tine l eak survey and pi npoi nt i ng t he l ocat i ons of l eaks.
o
Many agenci es syst emati cal l y survey areas out l i ned on maps.
meter reader r out es
as
they have been wel l t hought out and mni mze t he
di st ances i n cover i ng t he system
Ot hers f ol l ow
Greater f aml i ar i t y w th t he system
l ayout i s needed to ef f ect i vel y cover t he meter readi ng routes.
Exerclslng the h ydrant valve
helps pin point a leak.
o When usi ng the ground mcr ophone i n t urf areas t he use of a thumb tack
assi sts i n get t i ng bet ter sounds.
pl ate at tached
t o
a st r ong, met al , ver t i cl e spi ke.
of soni c l eak detecti on equi pment have i nf ormati on on thumb tacks .
A thumb tack i s a f l at , met al , hor i zont al
The manuf acturers
o
Some agenci es concentr ate on t he l i st eni ng phase f or several days and
pi npoi nt at t he end of t he week.
Except when saf et y i s
a
consi der at i on,
a
one- person cr ew i s ef f ect i ve f or
conduct i ng the l i st eni ng survey.
o
o
Leak Detect i on Sur vey Dai l y Log, as shown i n Exampl e 20 ( Page 74), can
6e used f or t he i ni t i al l eak det ecti on survey.
Bl ank f orms are l ocat ed i n
Appendi x
K
( page 127).
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Measuring and Estimating Losses from Discovered
Leaks
Losses from leak s th at a re discovered and rep aired should be measured t o
determine the rate of loss and the total volume lost during the l i f e of the
leak.
Douglas S. Greeley
i n
Water Emergency and_-Management Reference Number 1981):
o
Use
a containe r of known volume and a s top watch.
o Use a hose and a meter.
o
Calculate los ses using modified o ri f ic e and f ri ct io n loss formulas.
Three methods a r e suggested (from "Leak Detection Produc tivi ty ," by
36.
Service-ilne leaks can be easily
repaired b y replacing a part of the
service h e . Some agencies p lace the
damaged llne in l i ne with a test meter
and m easure the flow rate.
The f i r s t method, sometimes known a s th e bucket and s top watch method, i s a s
simple as
i t s
name.
Hold a container against the leak for a predetermined
time
period.
the time with a st op watch.
other container of known volume.
minute.
Use time interv als tha t are easy t o deal wi th.
Time in seconds:
6
10
15
30
Multiply volume i n gallons by: 1 0 6 4 2
t o g et gallons per minute.
f ie
conversion fac to r t o calcu lat e acre-feet for a two year
time
period, from
gallons per minute (gpm) :
Measure
Measure the water captured
with
a measuring cup or
Then convert time and volume t o gal lons per
60
_min/hr)(24 hrs/day)(365 days/fi2 ____ears) = 3.23
325,828 gallons per acre-foot
1.0
gpm fo r 2 yea rs = 3.23 ac re -fee t over t h e two-year average leak
lifetime.
Large spraying-type le ak s can be measured by drap ing an enveloping device (such
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a s
a large
canvas, rain
jacket, or
lar ge inverted pa il ) over
the
leak and
divert i ng th e water int o a container.
The second method r eq ui re s connecting a hose t o the leak and dir ecti ng the
flow
through a meter.
The
t h i r d
method is the simplest
t o
perform in the field but requires
calculations.
to o g re at t o measure and the main must be valved off.
I t
requi res tha t the
s i z e and shape
of
t h e
hole
be measured and t h e li n e pre ssu re be determined.
pressure gauge or a hand-held
blade
pitotmeter could be used t o determine t h e
pressure of t h e water coming from the lea k o r a nearby f i r e hydrant.
method al so us es some assumptions regarding the shape of t h e hole which may
introduce error.
For losses from such items a s pipes o r broken t ap s, Greeley assumes an orif ice
coefficient of
0.80 and calculates flow in gallons per minute from t h e formula:
Q
=
(43,767/1440)
x
A
x
square root
of
P
I I~
his method
i s
often helpful for large leaks
where
the
flow
is
A
This
where
Q =
flow i n ga llo ns per minute
A
= t h e cross sectional area of the leak in square inches and
P = t h e pre ssur e i n pounds per square inch.
For example,
i f
t
e
hole in t he p ipe were roughly circular, then the area would
be:
ascer ta in
the
pressure in the pipe.
For re la t ively small holes, the following leak rates in gallons per minute
(Table 5 ) were calc ulat ed, assuming a ci rc ul ar hol e and s ever al pressures.
9
A
= 3.14 x r .
You need only measure the diameter of th e hole and
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Calculating Leak R ates for Small Leaks
The following tables provide leak rates for typical meter box leaks.
These tables can be used t o convert dr ip s per second and cups per minute t o
gallons per
minute
t o be entered on
the
Leak Repair Report.
TABLE
4
LEAK LO SSES FOR CIRCULAR HOLES UNDER DIFFERENT PRESSURES
20 40 60 80 100 120 140 160
0.070
25
180
200
0.196
0.384
6
o 0.785
0.950
A R E A
I 20 -0
-
0
-
0 -00 -20 140
L E N G T H
7
9
1.767
1
180 200
-
60
-
2.270
2.545
2.836
o 3.142
1.061 1.510
1.850 2.136
2.388
4.271
6.041
7.399 8.544
9.522
9.611
13.593
16.648 19.224
21.493
17.081
24.165
29.597
34.115 38.209
26.699 37.158
38.471 54.372
52.331 74.007
68.350 96.662
86.506 122.338
106 .I98 151.035
129.225 182.152
153.789 217.490
46.245
53.399 59.702
66.593 16.894
85.911
118.387
136.101 152.840
90.640 104.662 iii.nio
149.833 173.012 193.434
184.979
213.596 238.807
223.825 258.451 288.951
266.310
307.578 343 2382
180.488
255.249
312.615
360.971 403.584
209.324
296.028
362.559
418.648 468.062
240.295
339.829 416.203
480.590 531.317
273.402
386.649
473.547 546.805
611.347
308.646 436.491
346.025 489.353
385.540 545.231
427.991 604.140
534.590 617.292 690.153
599.333 692.050 173.136
661.716
771.081 862.095
739.9 18 854.383 955.230
2.616 2.825
10.464 11.302
27.544 25.470
.
4i .a56 45 .zag
65.400 10.640
94.176 101 .I21
128.184 138.454
167.424 180.839
21 .896 228.874
261.600 282.561
316.536 341.898
376.704 406.887
442.104 411.527
512.731 553.819
588.601 675.162
66i.691 63.355
756.025 816.600
847.585 915.496
944.318 1020.040
1046.400 1130.240
3.021 3.204
12.083 12.816
21.186 28.835
48.331 51.263
15.518 80.098
108.745 115.341
148.014 156.993
193.325 205.052
244.676 259.5 19
302.070 320.394
365.505 387.676
434.981 461.361
510.498 541.465
592.051 627.912
619.658 720.886
173.299 820.208
812.983 925.938
978.101 1038.010
1090.470 1156.620
1208.280 1281.570
3.331
13.509
30.395
54.036
84.431
121.581
165.485
216.144
213.551
337.725
408.647
486.323
510.755
661.941
759.880
864.575
976.024
1094.220
1219.180
I350 .890
-
e a bo v e t a b l e
of
lasses f r o m r w g h l y c i r o u l a r s hs pe d h o l e s i n p i p e
is
c o m p u t e d
from
t h e f o l lo w i n g f o r m ul a e s t a b l i s h e d
Q z (30.394)(A)(square r o o t o f P ) g a l l o n s p e r m i n u t e
A i s
t h e
cross
s e c t i o n a l
area
of t h e l e a k i n
square
i n c h e s and
P i s
t h e p r e s s u r e i n p o u nd s p e r s q u a r e i n c h
__
____
TABLE 5
LEAK LOSSES FOR JOINTS AND CRACKS UNDER DIFFERENT PRESSURES
l e a k s e m i t t e d f ro m j o i n t s a nd c r a c ke d serv ice p i p e s an o r i f i c e c o e f f i c i e n t o f 0.60
i s
u s e d i n t h e f o l l o w i n g e q u a t i o n .
Q (22.796)(A)(square r o o t of P)
A is t h e erea
in
s q u a r e i n c h e s a nd P
i s
t h e p r e s s u r e i n p o un ds p e r square i n c h .
f o l lo w i n g t a b l e of f l a v r a t e s was c o m p u t e d i n g a l l o n s p e r m i nu te far f o u r d i f f e r e n t l e a k dimnsions u n d e r P P B S S U P ~ S
from
20
t o 200 p s i .
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TABLE 6
DRIPS PER SECOND CONVERTED TO GALLONS PER MINUTE
Drips per Second
Gallons per Minute
1
0.006
2 0.012
3 0.018
4 0.024
5
0.030
Note: Five dr ips per second amounts t o a steady stream.
TABLE
7
CUPS PER M INUTE CONVERTED
TO
GALLONS PER MINUTE
%ounce Cups per Minute
Gallons per Minute
0.25
0.50
0.75
1 .oo
1.50
2.00
2.50
3.00
3.50
4.00
0.016
0.031
0.047
0.062
0.094
0.125
0.156
0.188
0.219
0.250
Use the Leak Repair Report Form,
t o record a l l information regarding leak
excavation, flo w ra te s, and leak repair .
(See Example
21
on page 79.)
Determining Leak Detection Effectiveness
An important and often neglected par t of
t h e
leak detection project i s the
determination of whether th e pr oj ec t was a cos t-eff ect ive water conservation
measure.
the agency
must
evaluate the completed
leak
detection project.
To determine whether the leak det ectio n pr oje ct was cost ef fe ct iv e,
The
Leak
includes
Detection and Repair Project Sunwary (see Example 22 on page
81)
information needed fo r t h i s evaluation.
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EXAMPLE 21
LEAK REPAIR REPORT
Agency XYZ
Ccuntv Water Distr ict
11
5
85
(Month) (0.~1
M e 4
Date of Repair:
W.O. NO. 10077 Foreman Hal Nielson
Leak Iden tificot ion Map Reference
Refer
to
Leak Discovery Report
D i s c o v e r y b k 11 A A 5 LeakNo.=
Location: (include street mme and number) 9774
r;lra.=n
V i e w
Area 13
Page and Coordinates
1.
2.
3.
4.
5.
For Main and Service Lateral Leaks Only
Sketch
D m p
of the s i h ncluding:
If Moin or Service Leak,
Attach Three Photos:
Street name; north arrow
Meter number ( if ap plicab le)
Mains and hydrants in shutdown area.
A l l
valves, valve numbers and show
Locate leak to nearest inte rsecti on or house with address.
Show distances to property linez or street centerlines.
1.
2.
3.
which were closed during repair.
Straight down over leak
or mge
Close-up of leak and damage
An other photo which
you
feel
w i h help.
Leak Found ?
yes
Y e s h o )
Meter Leak -
Meter Spud Leak
-
Meter Yoke Leak -
Curb Stop Leak -
Domoged port was:
Y
epaired
If repaired, what repoirs were made?
-Leak Clomp
-
epacked valve
~ r b w ire 7 (persons)
-Welded - ecaulked ioint
Equipment Used for Repair
-Other (describe).
-
ackhoe
TYPE OF
LEAK
Main Lin e Leak - Joint Leak -
Service Lateral Leak
-
Other Leak
1L
Fir e Hydrant Leak _. Describe-c
Valve Leak _. Fliiqhi-
DESCRIPTION
OF REPAIR
-
eplaced I f replaced,
what
material was
used?
-
Renair t i m e 4 F r o m
o)
- umptruck
Repoir
Casts:
Size of Leak
Materials $ 11.19 Measured 3 - 1/2 GPM
Labor $ 114.72
Total $ 138.91
Equipment $ 12 - 00
Other $ 1.00
GP%
stimated -
1/2
ga l lon u c k e t
Method u.sed: Timed
with
stop
watch
79
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EXAMPLE
21
cont.)
annual water
loss
ra ti o versus sal es has been increasing a t a r at e of
1% which
would
te t ha t a percentage
of
these flushing
l i n e s
were already star t ing to leak
b a c k
i n 1981.
Descr ipt ion of Damage for
Mains
and Services
Type
of
Break
Flange nuts, bolts, t ie rods
-
plit
-
i p
h r r e l
-
Other (describe - ole
- oint
-
In your opinion, what caused the damage?
Whot part was damnged?
Circumferential split
alve
-
Broken coupling
Service pulled
Cracked a t corp. stop
Gasket blown
48
-
rushed pipe
Estima ted age of leak in months
How Determined *See top of page - racked Be l l
Diameter
of
Main
or
lateral in inches
Depth to top of pipe in inches
-
-
-
-
-
-
ther (describe)
Pipe Material:
-
alv.
Iron -
uctile
Iron -
. C.P.
System Pressure
How Determined
teel
-
.V.C.
- lock
Iron -
Cast
Iron
- opper
-
olybutylene
-
Examine broken edge of cost ord uctile iron pipe:
Origianol
of good grey is on:
thickness metal remaining
-
utride
Inches Inches
-
nside
Min. thickness Deterioration
Number of previous leak
s
there evidence of previous leak or
No repair clamps present
Cause of Leak
Y e s
-
epairs in same general area?
La st repair date (i f known)
-
No
-
o not know
n your opinion, should pipe be replaced? - e s -
FOR EXCAVATIONS INDICATE GROUND CONDITIONS
Type of k i l : Exis ting Bedding: Type
of Cover:
-Rocky
-
andy - raveVSand
-
oncrete
-Clay ~ Hard Pan x ative Soil
-
sphalt
-Adobe Loom - ea Gravel - oil
__Other
~
Other
-
ther
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EXAMPLE 22
LEAK DETECTION AND REPAIR PROJECT SUMM ARY
Agency: Xk'Z County
Water
D i s t r i c t
Name of Report Preparer:
Date:
November
30, 1985
C . M. B i n n s
Leak Detection Survey
TOTAL Number
of
Days Leak Surveys
were
Conducted: 65
First Survey Date: 7 / 1 0 / 8 5 Last Survey Date: 1 1 / 4 / 8 5
Number of Meters Flydrants Valves
Test
Rods Other
Listening
Points
Used:
13,786 1,067
--
505
0
Number of Suspected
Agency Leaks:
175
Pinpointed
I
Survey Time: Miles of Main Pinpoint ing
Time:
Surveyed: 124.7
-
2 hours
69
hours
--
Average survey rate
Miles
of main surveyed--
8 =
2.1
miles
per day
Total survey and pinpointing hours
TOTAL
number of
visible
leaks reported
since
survey started, from
0
ther
sources
(not discovered during leak detection surveys),
-
Leak Repair Summ ary
Date First Leak
Repair Made: 7 / 1 1 / 8 5 Repair Made: - 1 / 5 / 8 5
Number
of
Repair s Needing Number of Repairs Not
Excavation: 27 Needing Excavation: 148 Repaired Leaks:
-
75
TOTAL TOTAL,
Water Losses from
Water Losses from
Nonex- TOTAL
gater
Excavated Leaks: 203.5 gpm cavated Leaks: 2 .9 gpm Losses: 206.4 pm
Date Last Leak
-
TOTAL Number of
Excavated Leak
Repair Costs
Nonexcavated Leak
Repair Costs
TOTAL
Repair
Costs
Materials
$ 699 .36
Materials
$ 411 .68 Materials $
1 , 1 1 1
114
Labor
$ 4 ,377 .39
Labor $ 2 .255 .72 Labor
Equipment $ 561.4_0
Equipment 248 .75 Equipment $ 810 .50
$
6,633.11
Other $
35 .00
Other
$
83 .50
Other
$
118.50
Subtotal
$
F3- i -375 Subtotal $ 2,999.05 TOTAL $ 8,672.80
81
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EXAMPLE 22 (cont.)
LEAK DETECTION AND REPAIR PROJECT SUMMAR Y
Agency: XYZ County Water District
Date: November
3 0 , 1 9 8 5
Leak Detection Project Cost Effectiveness
Step
1.
Cal cul at e the val ue of water recovered
(Vwr)
f romal l repai red
l eaks.
(Vwr) = ( Tot al l eakage recovered i n gpm( Conversi on Factor)(Water cost , Wc)
Conversi on factor = 1 gpm f or
2
years
3.23
acre- f eet
Wc Li ne
19
of Wat er Audi t Repor t
=
wat er pur chase pr i ce
+
operat i ng cost s
per uni t of water
Vwr
= (
-
0 6 . 4
gpm ( 3 . 2 3 acre- f eet / gpm ( E$/ acr e- f eet )
s tep2.
Leak Detect i on Sur vey Cost s
V w r = $ 1 8 3 , 3 3 5
Det er m ne t he t ot al cost of t he l eak detect i on survey.
.........eak Detect i on Equi pment
$ 2 , 4 0 4 . 6 5
-
Leak Detect i on Trai ni ng ..........$ 4 0 0 . 0 0
Leak Detect i on Survey Costs
......
2 5 . 9 4 4 . 8 4
TOTAL COST of Leak Det ect i on Sur vey 2 8 , 7 4 9 . 4 9
Step3.
Di vi de
Vwr
f romSt ep 1 by t he tot al cost s cal cul ated i n St ep
2.
Benef i t : Cost Rat i o (B: C) equal s: Val ue of \ . l ater Recovered
Tot al Cost Leak Detecti on Survey
BC
I
. 4
__
For pl anni ng f ut ur e l eak det ect i on ef f or t s, you can cal cul at e aver age survey
cost s per ml e.
Step4.
Determ ne average survey cost s per ml e of mai n surveyed (C/M.
C/M
Tot al Cost of Leak Detect i on Survey $ 2 8 , 7 4 9 . 0 0
1 2 4 . 7 0
-
ot al Number of M l es Surveyed
M
C/M
=
$
2 3 0 . 6
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APPENDIX A
SAMPLE COMPLETED AUDIT REPORT &
LEAK DETECTION AND REPAIR PLAN
This
sample completed Water Audit report was used by
the
California Department
of Water Resources a s an example fo r p ar ti ci pa nt s t o follow in i ts statewide
Leak Detection Grant Program.
conducted water au di ts for a one-year period with emphasis on master and sales
meter accuracy plus unmetered water uses.
No
low-flow zone measurements
were
required, although
Participating water ut i l i t i e s and
dis t r ic t s
i n several instances,
they
might have been useful.
WATER AUDIT REPORT
Prepared by
XYZ
County Water District
This report includes the following items:
o a water audit worksheet
o
uncorrected t o t a l water supply
o adjustments t o to t a l water supply due t o source meter error
o uncorrected total metered water use
o meter tes t r e s u l t s
o
adjustments due to system service
meter
error
o a description of accounting procedures reviewed
o a description of actions taken to determine unmetered uses
o
a descri ptio n of acti ons taken t o determine water l os ses
o a summary of re comendat ions fo r system improvements proposed a s a re s u l t
of th e water a udit
o a leak detection and repair plan
A l l
discussions and tables refer t o t he l ine numbers of
the
Water Audit
Worksheet.
Subm itted by:
C.
M. Biees
Name
7 / 1 8 / 8 5
Date
M a n l
Title
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APPENDIX A
Page 2 of
19
WATER AUDIT W ORKSHEET
For the Water District:
LINE ITEM WATER VOLUME U N I T S
1 Uncorrected Total Water Supply
t o t he Distribution System
(Total of Master Meters)
Total
Subtotal Cumulative
11
, 2 7 0 , - Acre-feet
2 Adjustments t o Tota l Water
supply
2A Source
Meter
Error (+ or -1 + 254.5
Acre- fee t
2B
Change
i n
Reservoir and Tank
Acre-feet
__
torage (+ or
-)
+ 2 .5 .
Losses
(+
or
-)
2c Other Contributions or
0 Acre-feet
--
3 TOTAL
Adjustments t o Total
Water Supply (+ or -)
(Add L i n e s
2A, 28,
and 2C.)
+
257.0 Acre-feet
4
ADJUSTED
TOTAL
Water Supplied
t o the Distribution System
(Add Line
1
and
L i n e
3.)
11,527.0
Acre-feet
Uncorrected Total Metered
Water
Use
10,000 Acre-feet
5
6 Adjustments Due t o Meter
Reading Lag Time (+ or
-)
+
0 . 6
7 Subtotal: Metered Deliveries
(Add L i n e s 5 and
6 . )
10,000.6- Acre-feet
8
TOTAL
Sales Meter Error and
System Service
Meter
Errors
__I
04 .1
Acre-feet
(+ or-)
Deliveries (Add
L i n e s
7 & 8 . ) 10,504.7
Acre-feet
Water (Subtract Line 9 from
Line 4.)
9 C O R R EC TED
TOTAL
Metered Water
10
CORRECTED
TOTAL
Unmetered
Acre-feet
* The u n i t s of water measurement must be con si st en t throughout the worksheet.
Their se le ct io n (e.g., acre-f eet, mil lions of gal lons, hundred cubic
feet)
i S
l e f t to t h e user.
____
,022.3
I
4
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LINE
1 1
11A
11B
11c
11D
11E
11F
11G
11H
111
l l J
11K
11L
11M
12
APPENDIX A
WATER VOLUME UNITS*
Total
Page 3
of
19
Subtotal Cumulative
Author i zed Unmetered Water Uses
ITEM
Fi ref i ght i ng &
Fi r ef i ght i ng Trai ni ng 30.
5 .
Mai n Fl ushi ng -
I _
t ormDrai n Fl ushi ng 1 .5
Sewer Cl eani ng
2 .
St reet Cl eani ng
5 . 4
School s 0
Landscapi ng i n Large Publ i c Areas
Parks 140.
Gol f Courses 3 7 0 .
Cemeteri es 12.
Pl aygr ounds
19.
Hi ghway Medi an St r i ps
2 .
Ot her Landscapi ng 1 .
Decor at i ve Wat er Faci l i t i es
0 metered
-
0 metered
0 metered
Sw mni ng Pool s
-- --
Const ruct i on Si t es __
Water Qual i t y and Ot her Test i ng
( pr essur e t est i ng pi pe, water
Process Water at Treat ment
Pl ant s 0 . 2
Other Unmetered Uses
TOTAL Authori zed Unmetered
Water (Add Li nes
11A
t hr ough 11M )
0 metered
qual i t y, etc. )
-
-
0
__--
-
cre-feet
-cre-feet
Acre-feet
*
Acre-feet
Acre-f e-
Acre-feet
Acre-feet
A c r e - f e e L
-
cre-feet
Acre-feet
Acre-feet
A c r e - f e e e
Acre-feet
Acre-feet
Acre-feet
A c r e - f e e t
588.1 Acre-feet
-
as
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APPENDIX A
LINE ITEM
Page 4 of
19
13
14
14A
1 4 8
14C
14D
14E
14F
14G
14H
15
16
17
18
18A
18B
19
WATER
VOLUME
Total
Subtotal Cumulative
TOTAL Water Losses
(Subtract L i n e 12 from
L i n e
10.)
434.2
Iden t i f ied Water Losses
Accounting Procedure Errors
Illegal Connections
Malfunctioning Distribution
System Controls
Reservoir Seepage and
Leakage
Evaporation
Reservoir Overflow
Discovered Leaks
Theft
TOTAL
Identified Water Losses
(Add Lines 14A through 14H.)
Pdtential Xater System
Leakage (Subtract L i n e
15
from L i n e 13.)
Recoverable Leakage
(Multiply Line 16 by 0.75.)
Cost Savings
35.7
133.9
300.3
225.2
Dollars per Unit of Volume
Cost of Water Supply $ 225lAcre-foot
Variable
0
& Costs
$
- - ~ / & ~ e - f o o t
TOTAL Costs Per U n i t of Recoverable
Leakage (Add
L i n e
18A t o
Line
188.)
$ 275lAcre-foot -
UNITS*
Acre-feet
_--
Acre-feet
--
cre-feet
Acre-feet
-
cre-feet
Acre-feet
Acre-feet
Acre-feet
Acre-feet
Acre-feet
Acre-feet
Acre-feet
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Source
1 Source
2
Type of Measuring Device
Identification Number
(may be serial no.)
Frequency of Reading
Type of Recording Register
U n i t s Registers Indicate
Multiplier (if any)
Date of Installation
Size of Conduit
Frequency of Testing
Date of Latest Calibration
Source 3
V e n t u r i
0000278-A
Month
Daily
Dial
100,000
gallons
1
.o
1950
24 inches
Annual
4/1/84
Source Source 2 Source 3
Turnout Well Field City Monthly
41 Intertie
Totals
acre-feet acre-feet acre-feet acre-feet
Propeller
8759
Weekly
Dial
gallons
1
.o
1968
8 inches
2 years
8/21/84
V e n t u r i
OC
-
16
Daily
Builder Type
M
cubic
feet
100.0
1955
11.5
inches
4 months
1/15/85
January
February
March
April
Nay
June
July
August
September
October
November
December
TOTALS
-0-
-0-
-0-
400
815
920
930
1000
900
400
400
400
6, 165
-----
400
600
800
400
300
0
-0-
-0-
100
100
-0-
-0-
2,700
-----
320
200
-0-
-0-
-0-
250
260
275
100
300
400
300
2,405
-----
720
800
800
800
1, 115
1,170
1,190
1,275
1,100
800
800
700
11,270
-----
TOTAL Supply t o th e System
11,270
acre-feet
( En te r e d
on Line
1)
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APPENDIX A
Page
8
of 19
Month
UNCORRECTED TOTAL METERED WATER USE
Metered Subtotal
Residential Industrial Commercial Agriculture
( i n
acre-feet)
(i n acre-feet) ( in acre-feet) (i n acre-feet)
( i n
acre-feet)
Jan
Feb
Mar
April
May
June
July .
A%
Sept
Oct
NOV
Dec
Subtotal
450
500
500
800
815
700
500
500
-50
7,115
110
110
110
120
150
150
140
110
110
110
1,500
-
TOTAL
Uncorrected Metered Water
Use
25
25
25
25
25
25
25
25
25
25
25
25
300
-
-0-
0
-0-
75
175
230
175
230
200
0
0
-0-
1,085
-
585
635
635
770
980
1,105
1,150
1,220
1,065
635
635
-85
10,000
10,000
( E n t e r e d
on L i n e
5)
DETAILED METER LAG CORRECTION
The December through January billing period i s 62 days long.
Route Read Date Sales Adjustment
--
A 2/1/54
12 ac-f t 31/62
=
-6.0 ac-ft
B
2/10/84
10 ac-ft 21/62 = -3.4 ac-ft
C
2/20/84
11 ac-ft 11/62
=
-2.0 ac-ft
-11.4 ac-ft
ater
use
................................
A 2/ 1 85
I 3 ac-ft 31/62 6.5 ac-ft
B
21
I
0185
10 ac -ft 21/62 3.4 ac-ft
C 12/20/85
12 ac-f t 11/62 I: 2.1 ac-ft
Water Use
................................
+12.0 ac-ft
+0.6 ac-ft
(Entered on Line 6)
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APPENDIX
A
Page
9
of
19
Tot al Vol ume
Sal es at Fl ow Meter Meter Er ror
(ME)
Vol ume Vol ume Bate Regi st rati on ME Vf
-
Vf
BV) (Vt ) (Vf ) R) -
Meter Error
(ME)
( i n ac- f t)
100.0 7,115.0
TOTAL Resi dent i al Meter Error
=
.
412.1
Meter Dat e of
I D
Meter
I nstal l a- Manuf ac-
No.
Si ze
Type
at i on turer
Test Mean Regi st rati on at
Date Var i ous Fl ow Rates
91
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APPENDIX A
Pag e 11of 19
Line 11A Firefighting & Firefighting Ita inin g:
The f our f i r e compani es i n the servi ce area do not make
f i ref i ght i ng reports. The f i r e commander r evi ewed thei r l ogs.
They repor t 10 st ructural f i res and a 5- day w l d f i r e (water
ai r l i f t ed fr omopen reservoi r ) pl us
8
days
(48
hours) of t rai ni ng
where water was used.
Water Use Est i mates are:
Fi ref i ght i ng
20
acre-f eet
Tr ai ni ng 10 acre- f eet
TOTAL
........
30
acre- f eet
Line 11B Main Flushing:
Mai ns were f l ushed through r el i ef val ves and hydr ant s on 18
occasi ons (54hour s t otal ) account i ng f or approxi matel y
5
acre-
feet.
Line 11C Storm Drain Flushing:
The County Depar t ment of Wast e Water Treatment est i mates
approxi matel y 1.5 acre- f eet of water used to r el i eve congest ed
st or mdrai ns.
Line 11D Sew er Cleaning:
The County Depart ment
of
Wast e Water Treatment est i mates
approxi matel y 60 days work usi ng j et vactor and rel eases f rom
f i r e hydrant s f or an est i mated
2.0
acre- f eet of water .
Line 11E Street Cleaning:
County and communi t y hi ghway depart ment report s are combi ned i n
t he f ol l ow ng tabl e.
93
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A
Page 12of 19
No. of No. of
Capaci t y,
Ref i l l s Days Used
i n Gal l ons
per day per year
I_
Vol ume per
Vehi cl e per Year
i n Gal l ons
Parks
20.0
Playgrounds 2.7
Cemeteries 2.0
70
ft/acre
140
7.0
ft/acre 19
6.0
ft/acre 12
Gol f Courses - The 62 acre muni ci pal gol f course was est i mated by
measur i ng t he r ate of f l ow and det ermni ng t he l engt h of wat er i ng
per i ods.
Typi cal water appl i cat i on:
10
hour s per day
250
days per year
804 gal l ons per m nut e
yi el ds
120,600,000
gal l ons per year or
370
acre- f eet
Hi ghway medi an st r i ps are watered by l arge tanker t r ucks,
operat ed si ml ar t o vehi cl e I rBf f i n the st r eet cl eani ng operat i on.
yi el ds 500 gal l ons x 10 r ef i l l s per day x 130 day/ year =650, 000 gal
=2
acre- f eet
Another 1/4 acre memor i al park i s watered but speci f i c quant i t i es
are not recorded. Water use i s est i mated at 1 acre- f oot and
i ncl uded as l l Other l fandscapi ng.
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APPENDIX A
Page 13 of 19
Line 11K Water Quality Testing
Water amount s used f or test i ng are l ess than 500 gal l ons per year
( 0
acre- feet).
Line 11L Process Water
Treat ment pl ant operat ors do not mai ntai n speci f i c records.
oper at or s est i mat e 0.2 acre- f eet rel eased t o waste af t er f i l t er
backwash.
The
Line 14 Identified Water Losses
Line 14A Accounting Procedure Errors
Four meter readers were accompani ed on thei r r ounds f or one- hal f
day each. Thi s procedure sampl ed approxi matel y
800
connect i ons.
Thi s ef f or t pl us revi si on of t he bi l l i ng department ' s comput er
procedures r esul ted i n t he di scovery t hat 0.5 percent
of
r esi den-
t i al met er s were i noper abl e or msread.
Est i mat ed l oss:
0.005 x 10,200
connect i ons
x .7
acre- f eet / year
35.7
acre- f eet
Line 14B Illegal Connections
Dur i ng t he meter readi ng r ounds, one smal l shop was di scovered
usi ng water where t her e was no meter.
Est i mated l oss:
1
acre- f oot
Line 14C Malfunctioning System Controls
Usi ng an updated systemschemat i c al l systemcont r ol s were
methodi cal l y checked.
They al l operat ed correctl y.
Line 14D Reservoir Seepage
Each of t he syst ems cl osed r eservoi r s were i ndi vi dual l y val ved
of f f romt he system f or 24 hours.
eval uat i on.
One tank showed change i n
Est i mat ed annual l oss = 175 gal l ons
x
365 days
=
63,875 gal
= 0.2
acre- f eet
95
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APPENDIX A
Page 14 of 19
Hole Size
Diameter
Line 14E Estimated
lass:
Total Loss i n
Date of
Number of Days TOTAL LOSS
Gallons per Day
Repair
Leak Existed i n Gallons
Crystal Lake
is
an open reservoir of
5
acres surface area.
Estimated evaporation i n excess of rainfall
i s
6 feet per year.
Estimated
loss = 6
fee t
x
5 acres
=
30 acre-feet
Line 14G Discovered Leaks
Work records repo rt four excavations fo r leak repa ir .
emergency repairs with lar ge leaks believed t o be short-lived
(30 days undetected) due t o th ei r disr upti ve nature.
two
were
assumed t o have been ac t ive the ent ire year
u n t i l their
discovery. Leak r a t e s
were
not estimated
i n
the f ie ld .
The
ra tes
were
estimated
from
the appropriate hole
s ize
i n
the pipe
using Greeley's formula a s shown i n Table 5 of t h i s guidebook.
A l l mains involved operated a t 50 psi.
Two were
The other
1 243,000
5/15/83 30
7
, 90, 00
1 243,000
6/18/83
30
7 ,
90
000
0.25" 15,200 6/25/83
180
2,736,000
0.25" 15,200 10/28/83 300 4,560,000
TOTAL LOSS
......
21,876,000
= 67 acre-feet
Line 14H Thefts
No t h e f t s were ident i f ied.
Line 18A Cost
of
Water Supply
Purchase price of water from
CC
Aqueduct
z
$225/acre-feet
Line 18B
Variable Operations
&
Maintenance Costs
Power Purchases = $45/acre-foot*
Water Treatment
=
$Vacre-foot*
K F K l m T e p o r t t o -the S G t e Controller
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APPENDIX
A
Page 15 of 19
Sumnary of r ecommendat i ons for system i mpr ovement s resul t i ng f romwater audi t .
Conduct Leak Detect i on Program
Cust omer meters w l l be tested when recei ved f romt he manuf act urer
The revi sed account i ng bi l l i ng programs w l l check account s f or st opped
meters.
Recommendati ons ar e bei ng made that t he publ i cl y owned parks, pl aygr ounds,
cemeter i es, and gol f cour ses be metered.
The l eak repai r cr ew w l l be tol d to measure l eak di schar ge when l eaks ar e
uncovered.
Water audi t s are t o be per f ormed annual l y.
97
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APPENDIX
A
Page 16 of 19
LEAK D ETECTION AND REPAIR PLAN
WORKSHEET
Agency Name:
Y Z coun-tfia-ter District
Date:
7 / 1 8 / 8 5
A. Area to be Surveyed
1.
2.
3.
4.
Usi ng t he r esul t s of t he water audi t , show on a map whi ch areas
i n t he di st r i but i on systemw l l be surveyed.
areas have t he hi gher potent i al f or r ecover abl e l eakage.
Descr i be each area under B-2. ( I t ems to consi der i ncl ude r ecor ds
of previ ous l eaks, t ype of pi pe, age of pi pe, soi l condi t i ons,
hi gh pressur es, ground sett l ement , and i mproper i nst al l at i on
procedures.
)
Tot al m l es of mai n t o be surveyed: 146
.
I f l ess than t he
t otal system i s bei ng sur veyed, t he cal cul at i ons f or t he
benef i t : cost rat i o must ref l ect t he reducti on.
t he m l es of mai n, i ncl ude t he tot al l engt h of pi pe and excl ude
ser vi ce l i nes. 1
Average number of m l es of mai n surveyed per day:
Expl ai n i f more than
3
m l es per day.
can survey about t wo m l es of mai n per day.
i ncl ude di st ances bet ween ser vi ces, t raf f i c and safet y
condi t i ons, and number of l i st eni ng cont act poi nts. )
I ndi cat e whi ch
(When cal cul ati ng
2.0
I t ems to consi der
( The average survey cr ew
7 3
umber of worki ng days needed t o compl et e survey: _
( Di vi de Li ne
2
by Li ne 3.)
B. Procedures and Equipment
1.
Descr i be t he equi pment and procedure you w l l use to det ect l eaks.
EXDer i enCe has shown that t he best r esul t s have been obt ai ned bv
l i keni ng f or l eaks at _--l l syst emcont act poi nt s ( such as wat er -
met ers, val ves, hydr ant s, and bl owof f s).
Purchase Heath Son-i-Kit. Attend Manufacturers Seminars and
DWR
Training. Conduct initial listening survey on all contact
points.
I ___
I
I
- - -__
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APPENDIX A
Page
2
o f
4
Page 17 of
19
LEAK DETECTION AND REPAIR PLAN WORKSHEET
2.
3.
4.
5.
6.
Describe why
the
areas noted on
the
map A -1 ) have the greatest
potential for recovering leakage.
Ar ea
1
-
Downt ownL ol d duct i l e i r z a i n s
_ _
Ar ea 2 - St eel mai ns over 40 years ol d
Ar ea 3 - Remai nder of syst em
-
_ I ___
If
you
w i l l
not
be
l i st e n in g f o r l ea ks a t a l l
sys t em
contact
point s, descr ibe your plan for ef fec tiv ely detectin g leaks.
Not appl i cabl e
-
cr ew w l l l i s t en for l eaks on al l cont act
- -
poi nt s.
Describe
the
equipment and procedure you w i l l use t o pinpoint
the
exact location of the
detected
leaks.
W l l use l ow f r eauencv er ound m cr oDhone to l i st en over
~ e n t ~ s , . _ ~ ~ s r L L ~
n
-dLffiraalr si t uat ons.
__
-_
Describe how
the
leak detection
team
and
the
leak repair crew
w i l l work together. How
w i l l
they resolve
the
problem of dry
holes?
The l eak det ect i on cr ew and t he repai r cr ew wi l l j oi nt l y
excavat e al l l eaks f or t he f i r st 3 weeks and r esol ve and dr y
hol es t her eaf t er .
--
--
Describe the methods you w i l l use t o determine
the
f low ra tes for
excavated leaks of various sizes.
Bucket and st opwat ch met hod wi l l be used on smal l l eaks.
l arger l eaks the di amet er of t he hol e and t he pr essur e wi l l be
measured and used i n t he Gr eel ev f or mul a as shown i n t he Gui debook.
For
-
_. I _
99
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APPENDIX A
Page 18
of
19
LEAK DETECTION AND REPAIR PLAN WORKSHEET
Page
3
of
4
C.
Staffing
1.
How many agency st af f w l l be used? 2
Staff Cost I ncl udi ng Wages and Benef i t s:
Person 1 $/ hour 1 7 . 1 9 $/ day 1 3 7 2 -
Person
2
$/ hour
1 2 . 5 0
$/ day
-1M9n__
TOTAL $/hour 2 9 . 6 9 $/ day 237.52.-
2. How many consul t ant st af f w l l be used?
1
Cost of Consul t ant Staf f :
Person 1 $/ hour 3 1 . 2 5
__
$/ day 2 5 0 -
Person 2 $/ hour 0 $/ day ___
TOTAL $/ hour
3 1 . 2 5
-
$/ day
2 5 0
D. Leak Detection Survey Costs
Leak Detect i on Surveys: $/ day # DAYS Cost
1. Agency Crew Costs 2 3 7 . 5 2 7 3
$
1 7 . 3 4 0
2.
Consul t ant Crew Costs 2 5 0 . 0 0 1 5 $ 3 . 7 5 0
2 . 4 0 7 3
$
1 7 5.
Vehi cl e Costs
-
____
4 Other
5. TOTAL Survey Cost s
$ 2 1 , 2 6 5
E. Leak Detection Budget
2. Leak Det ect i on TeamTrai ni ng
$
_I_
. Cost of Leak Detect i on Equi pment $ 2 , 5 5 0
4 0 0
3.
Leak Detecti on Sur vey Cost s
$
2 1 . 2 6 5
-
4.
TOTAL Leak Detect i on Costs
$
2 4 , 2 1 5
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APPENDIX A
Page
19
of 19
LEAK DETE CTION AND REPAIR PLAN WORKSHEET
Page
4
of
4
E
Leak Survey and Repair Schedule
Indica te rea l i s t i c , prac t ica l da tes .
1 .
2 .
3. When w i l l
leak repairs begin? Augu?Ll& 1985
4. When
w i l l
leak repairs be completed? __ January
10,
1986
When
w i l l
the leak survey begin?
When
w i l l
the leak s u rv e y be completed? __ _ecember 15. 1985
August 1, 985
_I _
Prep ared by:
- C. M. Biggs -_7/ 8/85_
Name Date
Title
Manager
-- - - ___
101
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APPENDIX B
TYPES OF METERS
Velocity Meters
Propeller
The measuring element
i s
a rotor or propeller facing upstream that
is
rotated
by the moving water striking
i t s
angular blades.
diameter i n rel ati on t o the internal diameter of th e pipe, especially in the
larger sizes.
the re fore , th i s
meter
is intended primarily for main- l ine service
where
flow
rates do not change abruptly.
'Ihrbine
The
meter
co ns is ts of a very l i g h t waterwheel operated by th e current and
carries on its ax is a worm for a ctuatin g gearing and a to ta li ze r.
flow
is
computed from the rotations during a given period.
A
more
recent
design, th e magnetic flowmeter, requires electrical connections and
is
not a
ccmpletely self-contained un it .
Ultrasonic
Acoustic flowmeters operate on the principle that the propagation velocity
of
acoustic signals i n l iqu ids is changed when a component of the liquid's
veloci ty pa ra ll el s the direct ion of acoustic propagation. In practi ce, up t o
four acoustic paths are
set
up a t an angle t o
the
flow. Each path
consists
of
two i de nt ica l t ransd ucers facing each other a t a p rec ise ly known distance.
Typical path angles vary from 30 t o 65 degrees, depending on available space
and accuracy requirements.
determined by measurement of the acou st ic t rave l
time
i n each direction.
li qu id v elo cit y measured a t each path is integrated across the flowing area to
determine th e t o t a l volume flow ra te . Such meter systems have very critical
in s t a l l at i on requirements and, while excel lent ly amenable t o computer input,
ar e ra ther cost ly .
require turbid r ather than clear flu id t o work effectivel y.
Electromagnetic
The electromagnetic flowmeter uses the same basic principle as the
ele ctr ica l genera tor .
When a conductor moves across a magnetic field, a
voltage is induced
i n the conductor, and the magnitude of t he vol tage
i s
d i r ec t ly proport ional t o the speed of t he moving conductor.
i s
a section of conductive liquid flowing i n a nonconductive pipe through a
magnetic f i e l d , and e lec tro des ar e mounted i n the pipe wall, the voltage
induced across th e electr odes should be proportional t o the flow ra te .
The propeller may be small i n
The propeller has a slight lag
i n
st ar t i ng or stopping;
The rate of
The average liquid's velocity on each path is
The
Both ul t rasonic and doppler flow measurement techniques
If the conductor
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Differential Pressure
Flow TubedVenturi.
v e n t u r i t h roa t ,
i t s
veloci ty increases, resul t ing i n
a
pressure d i f f e ren t ia l
between the inlet and
throat
regions.
throat gradually increases in flow
area;
consequently, t h e f lu id ' s ve loc i ty
decreases, causing pressure recovery.
The
different ia l pressure across t h e
v e n t u r i ' s
throat can be recorded directly
or
t ransla ted into ac tual f low uni ts
by employing various types of di f f e ren t ia l pressure meters and capacity curves.
Venturi tubes are employed whenever the head
loss
is t o be minimized or
where f l u id s handled contain s uf fi ci en t amounts of materia ls
i n
suspension t o
render other devices such as or if i ce pl at es or flow nozzles
ineffec t ive ,
Widest ap plic atio n has tr ad it io na ll y been i n low-pressure gas
l ines
and large
water mains.
Measurements accurate to within plus
or
minus
0.5
percent can be made for
near ly a l l p ipe s izes.
arrangements may be critical.
V e n t u r i tubes
w i l l
maintain th ei r accuracy over re l at iv el y long periods.
I n
most
appl ica t ions the venturi is a self -cleaning device because i ts in te rna l
configuration allows smooth
flow
and minimizes erosion and clogging.
tubes
are mostly maintenance-free. They have no moving parts or mechanical
features or g lass tha t can
break or
become fatigued
or
st ra ined.
accuracy
of the
venturi
i s
d i f f ic ul t since al ter nat ive measuring devices
of
si mil ar accuracy and s i z e ar e oft en unavailable or d i f f i c u l t
t o
i n s t a l l .
ca l ibra t ing the venturi , it i s imperative t o check the venturi itself and not
j u s t the manometer apparatus.
with
the actual confirmed
flow.
with
a
hypothetical standard which
is
probably not occurring.
Orifice Plate.
is bored, u su all y con cen tr ica lly , a hole of predetermined siz e.
inserted across a st ra ight run of pipe.
Pressure
tap s ar e provided,
either
a t
specified distances upstream and downstream from the or i f ice plate or within
or if i ce flanges, by which th e orifice pla te is inser ted in
the l i n e .
The determination of the relation between
flow rates
and di ff er en ti al pressures
has
been reduced t o formulas by
which
an or if ic e coef fici ent can be readil y
computed for any size of
orifice
i n any size of pipe.
Pitotmeter.
pressure di ffer ence s associ ated with th e pi t ot tube when
it
is
inserted
i n t he
pipeline.
Then th e ve loci ty measurements a r e mul tip lied by the proportional
cross
sect ional area to determine the fluid
flow.
flows is t h e to ta l flow within t h e pipe.
A s
f l u i d
passes
through the reduced area of
t h e
That passage i me di at el y following th e
For larger diameter pipes piezometer rings and tap
Venturi
Testing the
When
Be su re t ha t
t h e
gauges a re cali br ate d
to
agree
Do not ad just the
manometer
apparatus
t o
agree
The
or i f ice sensing uni t cons is t s
of
a round plate i n
which
The
p l a t e
is
The
p i to t tub e measures f lu id v elo cit ies by
i ts
s e n s i t i v i t y t o
Velocity measurements a r e made along a tr an se ct in si de the pipe.
The
sum
of
a l l
th e proportional
Positive Displacement Meters
Disc Measuring Cham ber
The nutating disc
meter
consists of a movable disc mounted on a concentric
104
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sphere.
and top and bot tom surf aces that extend coni cal l y i nward.
f romrotat i ng about i t s own axi s by a radi al par t i t i on that extends across the
ent i re hei ght of t he worki ng chamber.
part i t i on.
axi s.
traces
a
ci rcul ar path as i t i s dr i ven by the nutat i ng mot i on.
The di sc i s contai ned i n a worki ng chamber w t h spher i cal si de wal l s
I t i s restr i cted
The di sc i s sl ot ted t o f i t over thi s
The water ent ers t he si de of t he meter and st r i kes t he di sc,
A
pi n ext endi ng out f r an the i nner spher e, perpendi cul ar t o the di sc,
f orci ng i t t o r ock (nutate) i n a ci rcul ar path w t hout r ot at i ng about i t s own
t he undergear t hat cont r ol s the meter' s regi st er .
Thi s pi n dr i ves
Compound Meters
Thi s meter measures over a w de range of f l ow, i ncl udi ng very l ow f l ows.
i s cal l ed %ompound' ' because i t has a l arge t urbi ne meter on t he mai n l i ne
and a smal l meter on a bypass l i ne, w th a val ve to di rect water t o one or the
other meter aut omati cal l y. Someti mes both meters are i n t he same housi ng.
Compound meters may have ei ther si ngl e or doubl e regi st ers.
I t
Proportional or Fire Line Meters
The proport i onal meter measures
a
smal l but r el at i vel y const ant percent age of
t he wat er f l ow ng through the l i ne.
meter regi st er
so
that i t r ecor ds t he total quant i t y that has passed through
t he mai n l i ne. Thi s i s accompl i shed by provi di ng an expanded sect i on of t he
l i ne w th a r i ng at t he downst reamend havi ng an i nt ernal di ameter equal to the
nomnal pi pe di ameter . The rest r i ct i on r i ng creates a drop i n l i ne pressure
j ust bel ow i t ( compared w t h f ul l l i ne pressure upstream. Thi s di f f erent i al
i n pressure f orces a por t i on of t he water through the smal l di spl acement - t ype
bypass meter.
A mul t i pl yi ng f actor i s bui l t i nto the
Open Channel Meters
Weirs
A wei r i s an obst r uct i on bui l t across an open channel over whi ch t he water must
f l ow
Sharp- crest ed wei r s have t hree basi c conf i gurat i ons:
and Ci pol l et t i .
Flumes
The water usual l y f l ows t hrough an openi ng or notch on the wei r pl ate.
r ect angul ar , V- not ch,
Fl umes are speci al l y desi gned, open channel f l ow sect i ons w th a restr i ct i on
that i ncreases f l ui d vel oci ty.
ci rcul ar pi pe sect i on.
They can be desi gned f or i nst al l at i on i n
a
Fl umes have sever al advantages over wei rs. The f l ow vel oci t y through f l umes i s
hi gh; t heref ore,
they tend t o be sel f - cl eani ng syst ems that mni mze deposi t i on
of sedi ment or sol i ds.
exper i enced w t h wei r s,
a
deci ded advant age f or i r r i gat i on.
Fl umes can operate w th much smal l er head l osses t han
A Parshal l f l ume i s empl oyed where i t i s i mpor tant t o mai ntai n a l ow head
l oss
or where t he l i qui d cont ai ns a l arge amount of suspended sol i ds.
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APPENDIX C
RECOMM ENDED USES OF METERS BY CLASSIFICATION
5 P e
Size
Applications
Positive
518"
Resi dences, smal l apart ment s, smal l busi nesses.
Displacement
Demand f l ow rates: 1/8 t o 29 gpm
Maxi mumcont i nuous demand to
10
gpm
3/41' Large r esi dences, smal l t o medi um apar tments.
Demand f l ow rates:
1/4
t o 30 gpm
Maxi mumcont i nuous demand to 15 gpm
1
I Medi um apar t ment s, beauty par l or s, barber shops, smal l
mot el s, f i l l i ng st at i ons, smal l busi nesses, i ndustr i al
processes.
Demand f l ow rates:
3/8
to
50
gpm
Maxi mumcont i nuous demand t o
25 gpm.
1-1/2 Medi ummot el s, hot el s, l ar ge apar t ment s, smal l
i ndust r y, smal l processi ng pl ants.
Demand f l ow rates: 5/8 to
100
gpm
Maxi mum cont i nuous demand to 50 gpm
2 Larger hot el s, mot el s, apar tment compl exes, i ndust r i al
pl ant s, processi ng pl ants.
Demand f l ow rates:
1-1/4
t o 160 gpm
Maxi mumcont i nuous demand to 80 gpm
Class II- 2 Medi um t o l ar ge hot el s, mot el s, l ar ge apar tment
Turbine
compl exes, i ndustr i al pl ant s, processi ng pl ant s,
i rr i gati on.
Demand f l ow rates:
3
to
200
gpm
Maxi mum cont i nuous demand tO
160
gpm
3" Lar ge hot el s, mot el s, i ndustr i al pl ant s, processi ng
pl ant s, i rr i gati on.
Demand f l ow rates: 4.3 t o 450 gpm
Maxi mum cont i nuous demand to
350
gpm
107
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TABLE C-1 (a n t. )
Lar ge i ndustr i al and processi ng pl ant s, i r r i gat i on,
r ef i ner i es, pet ro- chemcal s, pump di scharge.
Demand f l ow rates: 25 t o 2,500 gpm
Maxi mum cont i nuous demand
-
1,000
gpm
Lar ge i ndust r i al manuf actur i ng and processi ng pl ant s,
i r r i gat i on, pump di scharge.
Demand f l ow rates: 25 t o 2,500 gpm
Maxi mum cont i nuous demand -
2,000
gpm
4
6
Class
I-
8 I ndust r i al , manuf act ur i ng, pr ocessi ng, pump di scharge.
'lhrbine*
Demand f l ow rates:
140
to
1,800
gpm
Maxi mum cont i nuous demand - 900 gpm
10
I ndust r i al , manuf actur i ng, processi ng, pump di scharge.
Demand f l ow rates:
225
t o 2,900 gpm
Maxi mumcont i nuous demand to
1,450
gpm
Demand f l ow rates:
400
to
4,300
gpm
Maxi mum cont i nuous demand to
2,150
gpm
12
I ndust r i al , manuf act ur i ng, pr ocessi ng, pump di scharge.
Com pound , New High-
Velocity Styles
Medi um mot el s, hotel s speci al cust omers havi ng hi gh and
l ow demand; school s, publ i c bui l di ngs, l arge apar tment
and condomni umcompl exes, hospi tal s.
2
Demand f l ow rates:
1/4
t o
160
gpm
Maxi mumcont i nuous demand t o
160
gpm
3 Demand f l ow rates:
1/2
t o
350
gpm
4
Demand flow rates:
3/4
t o
1,000
gpm
Maxi mumcont i nuous demand t o
350
gpm
Maxi mumcont i nuous demand t o 1,000 gpm
Compound
6
Demand f l ow rates:
1-1/2
to
1,000
gpm
Older Styles
Maxi mumcont i nuous demand t o
500
gpm
8
Demand f l ow rates:
1
t o
1,600
gpm
Maxi mumcont i nuous demand t o
800
gpm
10
Demand f l ow rates:
4
t o
2,300
gpm.
Maxi mumcont i nuous demand t o
1,150
gpm
................................................................................
*
Cl ass
I
Tur bi nes bel ow
8
i nches ar e not i ncl uded because of t he hi gher per-
f ormance
of
Cl ass I1 mdel s.
108
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TABLE C-2
AME RICAN WATER W ORKS ASSOCIATION TURBINE METER STA NDARDS
FOR CUSTOMER SERVICE
Meter
Size
(in)
Safe Maximum Maximum Rate
Operating for Continuous
Capacity Duty
( P F d
kpm)
Maximum
Loss
Normal
of Head at Safe
Maximum Operating Flow
Capacity Limits
(psi
1-1/2
2
3
4
6
8
10
12
2
3
4
6
8
10
12
Class 1-VerticalShaft
&
Low-Velocity Horizontal Type
100 50 15
160 80 15
350 175 15
600
1,250
1,800
2,900
4,300
160
350
630
1,400
2,400
3,800
5,000
300
625
900
1.450
2,150
15
15
15
15
15
Class II-In-Line (High Velocity Type)
100
240
420
920
1,600
2,500
3,300
12 - 80
16 - 120
24
-
250
40
-
400
80
-
1000
225 - 2500
140 - 1600
400
-
4000
4 - 160
8
-
350
15
-
630
30 - 1400
50 - 2400
75
- 3800
120 - 5000
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APPENDIX D
METER SIZING PARAMETERS
When the type of
meter
has been selected, the meter should
be
properly sized
for operation.
This
means that
it
must measure the water ac cura te ly through
t h e
f u l l range of the customer's use.
maximum flow for short periods and a lower flow for long periods without
sustaining damage or above normal wear.
Meters mean revenue, and revenue can be lost because a
meter
does not register
accurately. Loss of re gis tr ati on can re su lt
from
wear, improper installation,
and improper s i z e or type of
meter.
Water meters ar e designed t o
d e l i v e r
a
I f a meter is operating outside i ts intended range,
i t
cannot regis ter a l l the
flow, even though i t may be accurate.
flow a t the change-over point,
the
loss
i n
revenue can
be
substant ia l .
A
24-hour or 7-day recorder a ttached t o a water meter w i l l provide maximum,
average, and minimum r a t e s of flow, which ar e ess en ti al i n determining whether
the
meter
is t h e proper s i z e and type fo r
the
ins tal lat ion. Without comparing
t h i s information
with
the meter's capacity,
the selection
of
a proper s i z e and
type of a water meter becomes a matter of guesswork based on experience.
large meter installations, a wrong guess based on experience that is not
representative of a particular situation can
be
costly and cause a considerable
loss of revenue.
Large water
meters
register flow inaccurately for several reasons.
a r e
these:
With a compound meter with appreoiable
For
Among them
The wrong size or type of water
meter
was
selected.
meter was selected to match the size of the service. From the standDoint
In some cases, the
of income, i t would be
better
to assume that the meter should
be
m a i l e r
than
the
service; however, t h i s
is
no time for assumptions. O f course,
flow should not be re s t r i c t ed ,
but with the amount of revenue a t s ta ke ,
meter sizing should
be
based on
the
type of factual
information provided by
a recorder chart .
A
change i n customers occurred a t a sp eci fi c lo cation.
profile of the new customer often differs considerably from that of the
The usage
original customer.
A change i n customer usage due t o water conservation or changes i n
production and/or products dealt with.
A
meter should
be
of adequate size
but
not oversized.
on
the
maximum
and
minimum demand and average usage rate of the customer.
Sizing should be based
The AWWA
has established standards on flow capacities and maximum pressure
losses for cold-water
meters.
lower pressure losses.
loss
flow curves provided by the manufacturer fo r newer models,
as appropriate.
N e w meters have a ls o been designed t h a t caused
The estimator can follow
the
AWA standards or the head-
1 1 1
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Tables
D-1,* D-2,*
and
D-3
provide data from which approximate pressure loss
can
be
determined.
curves of several types
of
1975-model meters and averaged t o produce t ab le s of
values that the estimator can use when rat ing curves are not available .
These
tables are not applicable to some of the e a r l i e r meters, and the estimator
should use then only as approximations for
late-model
meters.
There
are several important considerations
i n
sizing a
meter
ins ta l l a t ion .
The flow requirement, not the pressure loss through the meter, should determine
the size of
the
meter
t o
be ins ta l led .
pressure l o s s can mean low flows w i l l f a i l t o r e g i st e r.
the
cost of maintenance.
Furthermore, i f
there
is good reason t o bel iev e t h e
customer plans t o incr ease t h e demand for water, the estimator should provide
for large r metering fa c i l i t ie s la te r, adding a meter box and connections that
w i l l meet future needs.
These t ab les are based on pressure-flow da ta taken from
Oversizing a meter t o lower the
It
w i l l also increase
Size
( i n )
TABLE D-1
DISPLACEMENT-TYPE METERS MEETING AWWA SPECIFICATIONS
FLOW-PRESSURE LOSS AVERAGES OR 1937-MODEL MET ERS
Maximum Reconmended Design
Capacity Criteria -80 percent
AWWA
Flow of Maximum
Criteria Capacity
(gpm) (psi) (gpm) (ps i )
Recmended for
Continuous Flow- Brands
30
Percent of
Maximum Capacity
Meters
(gpm) (ps i ) Avgs
.
5/8 x
314 20 10.4
16
6.1
6 0
1 .o
6
314
30
10.6
24
6.9
9.0 1.05 6
1
50
9.3
40 6.3 16.5
1 .o 6
1-1/2 100
11.3
ao
8.6 30.0 0.9 6
2 160 10.4 128 6.5 38.0 0.5
6
3
300
13.1
240
8.3
90 0
1 1
3
* American Water Works Assoc iat ion , Sizing Water Service L i n e s and Meters9
AWWA
Number
M22.
112
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TABLE
D-2
COMPOUND-TYPE METERS MEETING AWWA SPECIFICATIONS
FLOW-PRESSURE
LOSS
AVERAGES
OF
1973-MODEL METERS
Si ze
(i n)
Maxi mum
Capaci t y
A W A Fl ow
Cri t eri a
(gpm (psi )
Recomended Desi gn
Cri ter i a- 80 Percent
of
Maxi mum
Capaci t y
(gpm
(psi )
2 160
9. 2
128
61
80 26 3
3 320
13.4
250
8.9 160
4.2 5
4 500
9.6
400 6.3 250
35 5
6
1000
9.4 800 5.8 500 2.5 4
8 1600 120
1280
7.8
800 4.O 3
Recomended for
Conti nuous Fl ow- Brands
Maxi mum Capaci t y Meters
(gpm)
(psi )
Avgs
.
30
Percent of
of
Si ze
(i n)
-
2
3
4
6
Recommended Desi gn
Cri ter i a- 80 Percent
of Maxi mum
Capaci ty
(gpm (psi )
TABLE
D-3
TURBINE-TYPE METERS MEETING AWWA SPECIFICATIONS
FLOW-PRESSURE LOSS AVERAGES OF 1973-MODEL METERS
Recommended for
Conti nuous
Fl ow-
Brands
50 Percent
of
of
Maxi mum
Capaci t y
Meters
(gpm (psi )
Avgs
.
Maxi mum
Capaci t y
A W A
Fl ow
Cri teri a
(gpm)
(psi )
160 4.5
350 4.6
600 3.5
1250 3.5
128
28 80 1 .o
280 30
175 12
480 2.1
300
0.8
1000
2.0 625
0.7
5
4
4
4
113
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APPENDIX
E
METER INSTALLATION CONSIDERATIONS
Correct
meter
i n s t a l l a t i on is highly important. Because a meter
is
a
mechanical device, it begins t o wear and lose accuracy from the day it is
insta l led.
i n s t a l l a t i o n t o
f i e l d
test
meters
i n line for accuracy.
When ins t al l i n g la rg e meters,
i n c l u d e
the following:
1 .
Isolation valves
i n
both the
in le t
side
and
the
out le t
s ide
of
t h e
meter.
2.
In
time
it w i l l stop funct ioning. Provisions should be made during
Test plugs downstream of
the meter
between the meter and
the
downstream
iso lat ing valve.
A meter
bypass
with
isolating valve or a bypass
meter
t o provide water t o
the customer while the meter is being serviced.
should
be
placed upstream of t h e inlet isolating valve and downstream of
the out le t isola t ing valve so t h a t
it
forms a U around t he main meter.
I f
a
meter i s
ins ta l led
with
a bypass meter, the bypass
meter
should remain
open and a check valve mus t be in st al le d downstream t o for ce the water at
low
flow
through
the
bypass
meter.
If
t h e
meter
i s
not installed
i n
t h i s
manner,
the
low flows w i l l pass unregistered through the large meter
because water
follows
the
path of least resistance.
The
check valve should
be either in te rn al ly spring-loaded or external ly controlled so tha t a
differential pressure of about
5
t o 10 pounds
is
requi red t o open th e check
valve.
If
meters
are ins ta l led i n pa ra l l e l , one meter should ac t a s a primary
meter
and the other as a secondary
meter.
downstream of the secondary meter t o
ensure
a pressure loss of a t l eas t 5
t o
10
pounds through the primary meter before the secondary meter begins
operating.
register low flows.
To
ensure proper
meter
functioning (by reducing turbulence), i n s t al l the
meters according t o th e manufacturer's spe cif ica tio ns governing the number
method i s to insta l l s t ra ightening vanes.
3.
The bypass connection
To do t h i s , place a check valve
This
provision
is
necessary t o make ce rt ai n both
meters
4.
of straight pipe diameters upstream and downstream of
t he meter.
Another
When
ins ta l l ing turb ine meters, use a strainer on
the
i n l e t
side
of the
turbine. The s tr ai ne r has two functions: t o keep forei gn matter
from
damaging
the turbine, and t o ensure th at the water approaching the turbine is f a i r l y
equal
i n
velocity across the
diameter
of the pipe and is not spiraling.
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APPENDIX F
METER TESTING IN GENERA L
A water
meter,
l i k e any other mechanical device, is su bj ec t t o wear and
deterioration, and, over a period of time,
it
loses i t s peak ef fi ci en cy . How
long water
meters
re t a in their overall accuracy depends on many factors, such
a s
t h e
qual i ty of the water being measured, r at es of flow, t o t a l qua nti ty,
chemical buildup, and abrasive materials carried by
t h e
water.
determine
whether a specific meter
is
operat ing eff ic ient ly is t o
test i t .
Meters are
tested
fo r sev eral reasons, including ( 1 ) determining
the
t o t a l
mount
of
meter error
w i t h i n the
distribution system;
(2)
ensuring that
the
co st of water s er vi ce is equitably d is tr ib uted among a l l customers; ( 3 ) deter-
mining the mount of revenue l o s t t o the water u t i l i t y ; and
(4 )
determining
whether a meter is capable of re gi st er in g low flows. Unfortunately, displ ace-
ment
meters, th e type most comonl y used, may se ri ou sly under reg ist er
for
long
periods without completely ceasing t o operate.
The
only way t o
Elements
of
a
Meter Test
The three basic elements needed t o test overall meter efficiency are:
1.
For the operating range of
the
meter, design ate the number of di f fer en t
f low ra t es t o be
tested.
A t each designated flow rate, determine the volume of water t o be passed
through
the meter
for each test .
2.
3.
Specify accuracy limits t ha t
meters
must meet a t d i f fe r ing ra t e s t o
be
acceptable for use.
Test Rates
Three
r a t e s of flow--minimum, in te rmedia te , and maximum--are necessary t o
properly
t es t
displacement, compound, and propeller meters. For compound and
fire-service meters,
the
changeover point must be establ ished to determine
overall operational efficiency and accuracy of registration.
important t o est ab li sh a t what point a meter begins t o reg is te r low flow.
Low flows below that point do not produce revenue.
The
meter
testing program should begin
with
the
low flow rates.
If
in the
course
of tes t ing,
the
meter
speed changes,
be
sure there was no use by
the
customer.
since
the
high flow could flush out sand
and
other materials.
would t o t a l l y negate l a t e r low flow tests.
The intermediate rate
of
flow should be a t or near the high point of
regis t ra t ion (about 10 percent of rated capacity) t o ensure th at the meter
w i l l
not over re gi st er a t any r at e of flow.
Tests for full-flow accuracy are not necessary a t the "safe
maximum
capacity"
r a t e
shown
i n
the
appropriate
AWWA
standard because
meters
are
seldom
operated
It is a l so
High flows must be avoided pri or t o low and medium flow testing
Such flushing
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a t rated capacity.
but is usually about 10 percent of rated
meter
capacity.
the accuracy curve is fa i r ly f la t , and accuracy differs
l i t t l e
over a wide
range of flows.
capacity are practical .
of small
meters.
The maximum point of registration depends on meter design
A t rates above that,
Maximum-rate
test
flows of about three- fourths of rat ed
They are esp eci all y advantageous i n mult iple tes t ing
Accuracy Limits
Accuracy
limits
are establ ished to ensure that water meters record as
accurate ly a s pos sib le and as commercially fe asi bl e.
register variably by
2
t o
3
percent over the e n t i r e range of flows.
not occur when t h e flow
is
s o low that i t f a i l s t o re gi st er. ) For example, a
5/8-inch
meter
i n good condit ion
w i l l
reg is te r w i t h i n the following limits:
95 percent or higher with a 1/4-gpm flow; a t a maximum of 101.5 percent with a
2-gpm flow (usually
10
percent of rated
meter
capa city ); and then a t not
less
than 98.5 percent with a 20-gpm flow.
It
i s not normally considered economically fea si bl e t o rep air older meters t o
bring them up t o t he accuracy
levels
achievable by new meters a t the minimum
ra te .
tables for
new
and repaired meters on the minimum flow test. The
l i m i t s set
for repaired
meters
ar e considered t o represent t hose t h at requir e good
meter
shop procedures. Repaired
meters
should re gi st er a t l e as t 90 percent on t h i s
test .
standards.
Meters tend to
(This does
a t
For t h i s reason, separate accuracy
limits
are shown i n
t he
following
A higher percentage
i s
recomended for desirable shop quality
Meter Test Alternatives
Meters can be tested in-place ( f i e l d t e s t ing) or i n the
meter
shop (bench
tes t ing) .
Field Testing
As t h e cost of meter removal and replacement increas es, f i e l d te s t ing becomes a
more attractive method.
portable meter test uni t
i s
adequate for smaller meters.
equipment compares a previously calibrated meter with the meter being tested.
I n f ie ld tes t ing , both
meters
must be f u l l of water and under p os it iv e pressure
and the c on tr ol valve t o regu la te flow must always be on
t h e
discharge
s i d e
of
the
cal ibra ted
meter.
Large meters can be tested with a pitotmeter.
The
The portable test
Bench Testing
A
meter
shop typica ll y uses equipment th a t va ri es from a simple Rotameter (r at e-
of-flow ind icat or) t o a volumetric test bench that can test several meters a t
one
time.
Rising costs of meter removal and replacement a re a l so causing many
u t i l i t i e s t o phase ou t t he i r meter shops and either replace their meters
without test ing, or send
them
ou t t o
be
tested.
For a detailed description of meter t e s t i ng , r e fe r t o the American Water Works
Association (AWWA) pub lica tion ,Water Meters--Selection, Ins ta ll at io n,
Testing, and Maintenance,
AWWA
Number M6.
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APPENDIX G
METER TESTING WITH A
PITOT
ROD
The purpose of the p i to t rod is t o measure the
flow of
l i qu id
i n
a closed
conduit under pressure.
conduit and the diameter of the condui t. From these measurements,
t h e
flow
can
be calculated.
accuracy cannot be obtained with an "averaging pitot rod" but only with
a
p i t o t
rod th a t ca lcula tes the ve loc i ty prof i le .
The pitot rod can be used on any closed conduit which has been re t r of i t te d with
a one-inch corporation cock.
operator i n about two hours with good conditions.
The pitot rod can be u s 4 t o test the accuracy of large water meters, measure
the
flow
of a pipe, perform loss
of
head
tests,
determine Hazen's flow
coefficients, perform zone measurements, conduct f i r e flow tests, determine
di rec t ion of
flow,
determine 24-hour flows, and i nd ic ate flow rev ers als .
For directions on using a pi to t rod , refer t o t h e manual Practical Hydraulics
and Water Flow Monitoring Work&*, developed by Carl F. Buettner Workshops.
* Revised July 1982, Polcon Inc ., St . Louis, Missouri
The p i t o t rod measures t h e ve lo ci ty of f l u i d i n t h e
The
p i to t rod can be accurate to within about 2 percent. This
The
test
can be performed
by
an experienced
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APPENDIX
H
LONG-TERM METER SURVEILLANCE
(Well-Suited For Large Meters and Large Revenue Producing Customers)
After
a meter has been tested and calibr ated , sur veil lan ce or review of
consumption records should be ini t ia t ed t o ensure the meter
w i l l
operate as
long and as accurately as possible a t th e l ea st possible cost .
A useful technique is t o review bi ll in g records a t regular periods f or each
meter.
necessary.
quarterly or semi-annual review w i l l be suffic ient .
l ea s t a 12-month period t o guard ag ains t seasonal changes i n
the
customer's
water use pattern.
n o t
changing and t he consumption records a r e dec linin g, then
the
meter may be
losing accuracy and should be scheduled for inspection and testing.
Flow rates
w i l l
vary from customer t o customer, even
where
meters of
the
same
s ize
are i n use.
useful t o record each customer's ty pi cal maximum and minimum monthly usage.
This
information can
be
used t o an ti ci pa te demand.
Computerization helps immensely, otherwise sampling techniques may be
It is not necessary t o review records every bi ll in g period; a
Compare the records for a t
Contact t h e customer and i f the customer's ac tu al usage
i s
Rates of use a ls o vary
with
the
season of
the
year.
It
i s
1 2 1
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APPENDIX
I
CALCULATING EVAPORATIVE WATER LO SS
Evaporat i ve water l osses f roml arge bodi es of water i ncl ude water l ost di rect l y
t o the at mosphere f romopen- ai r ,
st andi ng bodi es of water .
are par t i cul ar l y si gni f i cant dur i ng hot weather at l ar ge unmet ered pool s and
reservoi rs.
f ountai ns.
Ponds and reservoi r s i n Cal i f orni a annual l y l ose an aver age of
50
t o
80
i nches
of water by evaporat i on.
Dur i ng the sumer , dai l y evaporat i on l osses may be
0. 33 i nches per day f romeach acre of pond or reservoi r sur f ace (about 9,000
gal l ons per day per acre).
Exposur e to w nds and hi gh ai r t emperatures are
pr i nci pal cont r i but i ng f actors.
over the water sur f ace, and the ai r i ncreases i t s capaci t y to hol d moi st ure as
i t s t emper at ure r i ses.
Cal cul at i ons of evaporat i ve l osses are possi bl e, but they are al so compl ex,
and t hey r equi r e detai l ed l ocal envi ronment al data not other w se normal l y
avai l abl e. To est i mate evaporat i ve l osses, use t he evaporat i on pan dat a for
l ocat i ons i n Cal i f orni a shown here i n Tabl e
1-1,
an excerpt f romEvaporat i on
f romWater Sur f aces i n Cal i f or ni a, Bul l et i n 73- 79, Cal i f orni a Depar t ment
of
Water Resources.
l ocat i ons t hroughout Cal i f orni a.
Evaporat i ve l osses
I t
i s
of t en di f f i cul t t o est i mat e l osses f romsmal l pool s and
The w nd di sr upts t he saturated boundary l ayer
The bul l et i n provi des monthl y t ot al evaporat i on data at 478
123
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TABLE
1-1
MEAN A NNUAL EVAPORATION AT PRINCIPAL CALIFORNIA LAKES
(inches)
Location
Berryessa
Cachuma
Castaic
Clair Engle
Clear
Eagle
Elsinor
Folsom
Henshaw
Hetch Hetchy
Isabel la
Matthews
Millerton
Nacimiento
Oroville
Perris
P i n e
Fla t
Pyramid
San Antonio
San L u i s
Shasta
Silverwood
Success
Tahoe
Inches
78
69
a i
57
60
48
75
67
71
46
a7
74
86
71
67
68
87
76
109
68
a7
a7
.
a2
38
The
evaporation data i n Table 1-1 and Bulletin
73-79
represent what
is
sometimes called gross evaporation, which
i s
the actua l depth of water lo s t t o
the
atmosphere.
shown t o be la rg er than those for lak es, the data referenced here does not take
this into account. No adjustments of these da ta are expected t o be made by
users of
t h i s
Guidebook.
Although evaporation rates for evaporation pans have been
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APPENDIX
J
LEAK DETECTION EQUIPMENT
(A
Partial List dated December 1991)
Thi s l i st may not cont ai n al l manuf act ur er s
of
l eak det ect i on equi pment
or
accur at e pr i ces.
equi pment .
DWR
makes
no
r ecommendat i ons on t he capabi l i t y
of
any
The i nf or mat i on pr ovi ded may not be cur r ent and ot her equi pment
may be avai l abl e.
5 P e Company
Soni c Heat h
Soni c Fi sher
Soni c Met r ot ech
Soni c Fl ui d
Conser vat i on
Syst ems
Soni c
,
Gol dak
Soni c Subt r oni c
Fuj i Tecom
Fuj i Tecom
Fuj i Tecom
Acoust i c Pol l ar d
Cor r el at or FCS
Cor r el at or Rubl e
Model
Aqua- Scope
Son- i - ki t
XLT- 20
HL- 20 0 0
HL
90
200L
s 20
777-A
WL- 200
HG- 10
FD-7
Geophone
9090
1000
Price
$ 1 ,6 5 5
$3,900
$ 1 ,3 4 5
$ 3 ,1 7 5
$ 1 ,3 4 8
$ 8 0 2
$ 2 ,9 0 0
$ 985
$2 ,178
$2 ,275
$
765
$
275
$44,000
$25 ,000
20,000
Telephone/State
9 1 / 37 1-2 52 0
(
CA)
916/371-2520 ( CA)
209/826-3292 ( CA)
415 / 940-4 90 0 (CA)
800/531-5465
(TX)
512/794-0222 (TX)
818/240-2666
( CA)
510/ 68 6-37 4 7 (CAI
510 / 68 6-37 47
( CA)
510/686-3747
( CA)
5 16 /7 4 6 -0 8 42
(NY)
800/531-5465 (TX)
512/794-0222 (TX)
800/347-8253 (MN)
The Amer i can Wat er Works Associ at i on Buyer ' s Gui de may l i st addi t i onal
equi pment .
303/794-7711 (CO)
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APPENDIX K
WATER AUDIT AND LEAK DETECTION FORMS
NOTE
The forms in Appendix
K
may be “snapped
out”
for your convenience and ease of calculation.
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WATER AUDlT WORKSHEET
Page 1
of
4
For
Water District:
Line
1
2
2A
2B
2c
3
4
5
6
7
a
9
10
Item
Uncorrected Total
Water
Supply
t o the Distribution System
(Total of Master Meters)
Adjustments t o
T o t a l
Water
Source Meter Error (+ or
-1
Change
i n
Reservoir and Tank
Storage (+
or -1
Other Contributions
or Losses (+ or
-1
TOTAL Adjustments t o Total
Water Supply (+ or -1
(Add
L i n e s
2A, 2B, and 2C.)
ADJUSTED TOTAL Water Supplied
to
the Distribution System
(Add
L i n e
1 and L i n e
3.)
Uncorrected Total Metered
Water
Use
Adjustments
Due
t o
Meter
Reading Lag T i m e (+ or
-1
Subtotal: Metered
Deliveries
(Add L i n e s 5 and 6 . )
TOTAL
Sales
Meter
Error
and
System Service
Meter
Errors
(+ or -)
CORRECTED
TOTAL
Metered Water
Deliveries (Add L i n e s 7
&
8.)
CORRECTED
TOTAL Unmetered
Water (Substrac t l i n e 9
from
L i n e 4.)
Supply
Water Volume Units' _
Subtotal Cumulative _
_
Total
_I
-units
of water
measurement
must
be consistent throughout the worksheet.
Their selection (e.g.,
acre-feet,
millions of gallons, hundred cubic-feet) i s
l e f t to the user.
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Page 2 of 4
Line
11
11A
11B
11c
1 1 D
11E
11F
11G
WATER AUDIT WOR KSHEET
Item Water Volume
Total
Subtotal Cumulative
Authorized Unmetered Water
Uses
Firefighting
&
Firef ighti ng Training
Main Flushing
Storm Drain Flushing
Sewer Cleaning
Street Cleaning
-
Schools
Landscaping I n Large Public Areas
Parks
Golf Courses
Cemeteries
Playgrounds
Highway Median St r ips
Other Landscaping
11H Decorative Water F ac i l i t i e s
1 1 1
Swimning Pools
l l J Construction Sit es
11K
Water Qual i ty and Other
Testing (pressure testing
pipe, water quality, etc.)
11L Process Water a t Treatment
Plants
11M Other Unmetered Uses
12 TOTAL Authorized Unmetered
Water (Add
L i n e s
1lA
through 11M.)
Units*
--
I
-
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Line
13
14
14A
14B
14C
14D
14E
14F
14C
14H
15
16
17
18
18A
18B
19
Item
WATER
AUDIT
WORKSHEET
Water Volume
Total
Subtotal Cumulative
TOTAL
Water Losses
(Substract
L i n e
12 from
Line 10.1
I den t i f i ed
Water Losses
Accounting Procedure Errors -
Illegal Connections
Malfunctioning Distribution
System Controls
Reservoir Seepage and
Leakage
_I
Evaporation
I_
Reservoir Overflow
I
Discovered Leaks
-
. I
heft
TOTAL Identified Water Losses
(Add L i n e s 14A through 14H.l
Potential Water System
Leakage (Subtract Line 15
from Line 13.)
Recoverable Leakage
(Multiply Line 16 by 0.75.)
Cost
Savings
Dollar= U n i t of Volume
I_
Cost of Water Supply
-
Variable 0 & Costs
$ -
TOTAL Costs Per Unit of
Recoverable Leakage
(Add
Line
18A
t o Line
18B.) $
Page
3 of 4
Units*
131
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Page
4 of 4
WATER AUDIT WO RKSHEET
Line Item
20 One-Year B e n e f i t fran
Recoverable Leakage (Multiply
Line
17
by
L i n e
19.)
21 TOTAL BENEFITS from Recoverable
Leakage
TOTAL COSTS of Leak Detect ion Project
(Multiply L i n e
20
by
2.)
22
23 Benefi t t o Cost Ratio
(Divide
L i n e
21 by L i n e 22.)
Prepared by:
Dollars per year
$
$--
-
Date
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LEAK DETECTION AND REPAIR PLAN
WORKSHEET
Page 1 of 4
Date:
Agency Name: _ _
A. Area to
be
Surveyed
1.
2 .
3.
4.
Using the res ul t s of the water audi t , show on a map
which
areas
i n the
distribution system w i l l be surveyed.
areas have the higher potential
f o r
recoverable leakage.
Describe each area under
8-2.
(Items t o consider include records
of previous leak s, type of pipe, age of pipe, s o i l conditions,
high pressures, ground settlement, and improper installation
procedures.
Total
miles
of
main
t o be surveyed:
total system i s being surveyed,
the
calcula t ions for the
benefit:cost r a t i o must r ef le ct the reduction.
the
miles of main, include t he total length of pipe and exclude
service l ines .
Average
number
of
miles
of main surveyed per day:
Explain i f more than 3
miles
per day a r e surveyed.
survey crew can survey about two miles of main per day.
consider include distances between services , t r af f ic and safe ty
conditions, and number of listening contact points.)
Indicate
which
.
If
less
than the
(When calculating
(The average
Items t o
Number of working days
needed
t o complete survey:
(Divide Line 2 by Line
3 . )
B. Procedures and Equipment
1.
Describe the equipment and procedure you w i l l use t o detect leaks.
Experience has shown that
the
best
re su lt s have
been
obtained by
lis ten ing for leaks a t a l l system contact poi nts (such as water
meters,
valves, hydrants, and blowoffs).
133
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LEAK DETECTION AND REPAIR PLAN WORKSHEET
Page 2 of 4
2.
Describe why t he area s noted on t h e map A - 1 ) have the greatest
potential for recovering leakage.
_____ _ _ __
_ _ _
3.
I f you
w i l l not
be l i s ten ing
for
leaks a t a l l system contact
point s, describe your plan f or ef fec tiv ely detecting leaks.
4. Describe the equipment and procedure you w i l l use
t o
pinpoint the
exact location of t h e detected leak s.
5.
Describe how the leak detection team and t he leak rep air
crew
w i l l
work together.
How w i l l
they resolve t he problem of dry
holes.
6.
Describe the methods you w i l l
use
t o
determine the
flow
rates for
excavated leaks of various sizes.
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Page 3 of 4
1.
2.
How many agency s t a f f
w i l l be
used?
Staff Costs Including Wages and B e n e f i t s :
Person
1
$/hour
$/day -
Person
2
$/hour
$/day
TOTAL
$/hour
-
/day
How many consu lta nt s t a f f
w i l l be
used?
Cost
of Consultant Staff:
Person 1 $/hour $/day
Person 2 $/hour $/day
TOTAL $/hour $/day
Leak Detection Survey
Leak Detection Surveys: $/day
1.
Agency
C r e w
Costs
2. Consultant Crew Costs
3. Vehicle Costs
4.
Other
5. TOTAL
Survey Costs
. Leak Detection Budget
1 .
2.
Leak Detection Team Training
3. Leak Detection Survey Costs
4.
TOTAL Leak Detection Costs
Cost
of Leak Detection Equipment
Days Cost
$
135
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LEAK DETECTION AND REPAIR PLAN WORKSHEET
E
Leak Survey an d Repair Schedule
Indicate real i s t ic , pract ical dates .
1.
When
2. When
3. When
4. When
w i l l
w i l l
w i l l
w i l l
Page
4
of
4
leak repai rs
leak repairs
the leak su rvey begin?
the leak survey be completed?
~
_
_ I _
begin? -
be
- --
ompleted?
Prepared
by:
--
Name Date
136
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LEAK DETECTION SURVEY DAILY
LOG
Agency
Da to
__-
M o n t h
Day Yeor
Leak Detection Team Members:
Manufacture and models o f Equipment used:
Area Surveyed Map Reference
_
Street and
Block
N o r :
~
Page
-3
Coordinates
LEAK LOCATION O R ADDRESS AGENCY OR LEAK
LEAK TO BE LEAK NOT A
NO.
O F
SUSPECTED LEAK CUSTOMER PINPOINTED RECHECKED REPA IRED LEAK
A O R C Y OR N
Y OR N Y OR N DATE
I
I
I
I
I
~~ _____~
Indicate Number of Meter s Hydr ants
V o l v a s
L ia t e n in g P oin t s U s e d
- - -
Tes t Rods Other
-
-
Mi l * .
o f
Main Surveyed
-
Survey Time
- o u r s
Number
4
Leaks Suspected
T o
be rechecked ___
Number
Number o f Leaks P inpo in ted
-
Pinpo in t ing T ime
-
ours
Rema rks :
137
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Page
1
of
2
LEAK REPAIR REPORT
Date of Repair:
(Month)
I D w ) (Y*a,)
WO No.
Foremon
~
Leak Iden tific ation Map Reference
Refer to Leak Discavery Report
Discovery Date Leak
No
Loca tion: (inc lude stree t name and number)
_
Page and Caardinates
For Main and Service Lateral Leaks Only
Sketch
a
rmp af the s itu including:
1.
Street nmme; north arraw
2. Meter number (if applicable)
3.
Mains and hydrants in shutdown
area.
4.
A l l
valves, valve numbers and show
If
Main ar Service Leak,
Attach Three Photos:
1.
Straight dawn aver leak
or
damage
2. Close-up of leak and damage
which were closed during repair.
5. Locate leak ta nearest intersection ar house with address.
Show distances to property liner or street centerlines.
3.
An
ather photo which you feel
w i h help.
Leak Found
?
( Y e r h o ) TYPE
OF
LEAK
Meter Leak
- Main Line Leak _. Joint Leak
-
Meter Spud Leak - Service Lateral Leak -
Other
Leak -
Meter Yoke L eak
-
Curb Stap Leak __
Fire Hydrant Leak - Describe
Valve Leak -
DESCRIPTION OF REPAIR
Damaged part was:
-
epaired
-
eplaced
I f
replaced, what material wos
I f repaired, what repairs were made?
Repair time (From To)
__Leak Clamp
-
epacked valve
Crew Size (perrons)
-Welded
-
ecaulked ioin t
Equipment Used far Repair
-Other (describe).
- ackhoe
-
umptruck
Repair C o s t s : Size of Leak
Materials
$
Measured GPM
Labor $
Equipment
$
Other $
Total
L
Estimated GPM
Method used:
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R REPORT
Page 2 of
2
Description of Damage for Mains and Services
Whot part wns damoged?
Pipe barrel
-
lange nuts, bolts, t ie rods - plit
-
oint
-
ther (describe
-
ole
Valve - ircumferential split
Type
of
Breo
k
-
-
Broken coupling
Service pulled
Cracked at corp. stop
-
In your opinion, what caused the damage?
-
-
-
asket
blown
-
rushed pipe
Estimated age of eak in months
How Determined - racked
Be l l
Diameter of Main
or
lateral in inches
-
ther (describe)
Depth to top of pipe in inches
Pipe Moterial:
System Pressure
How Determined
-
al . Iron
-
uctile
Iron - . C.P.
- lack Iron
-
teel -
.V.C.
- ast
Iron
- opper
-
olybuty
lene
Examine
broken
edge of ca rt or ductile iron pipe:
Min. thickness Deter iorotion
Origiona I of good grey is on:
thickness metol remaining - utside
Inches Inches
-
nside
I s
there evidence
of
previous
leak
or
repairs in
same
general orea?
- es
-
o
repair clamps present
Las t repair date (i f known)
Number
of
previous leak
Cause of Leak
No - o not know
In
your opinion, should pipe be replaced?
-
es
-
If yes, exp lain extent:
FOR EXCAVATIONS
INDICA TE GROUND
CONDITIONS
Type
of
Soil: Exis ting Bedding: Type of Cover:
Rocky - andy - ravelhand - oncrete
-Clay
-
ard Pan
-
ative Soil
-
sphalt
-
oam
- ea Grovel - oil
-
ther
-
ther
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LEAK DETECTION AND REPAIR PRO JECT SUMMARY
Page 1of 2
Agency ~
Name
of
Report Preparer
__
-
Date
~
Leak Detection Survey
TOTAL
Number of Days Leak Surveys
were
Conducted:
First Survey Date:
Number of
Meters
Hydrants Valves Test Rods
Other
Listening Points Used:
Last Survey Date:
Number
of Suspected
Agency Leaks:
Pinpointed
Survey Time: Miles
of
Main Pinpointing
Time:
hours
hours Surveyed : _ _
Average survey rate = Miles of main surveyed x 8 = miles per day
T o t z s u r v e y and pinpointing hours
TOTAL
number of v is ib le le aks reported sin ce survey s ta r te d, from
other sources (not discovered during leak detection surveys).
Leak Repair Summary
Date First Leak
Repair Made: Repair Made:
Number of Repairs Needing
Date Last Leak
Number of Repairs Not
TOTAL Number of
Excavation: Needing Excavation: Repaired Leaks:
-
TOTAL
TOTAL
Water Losses from Water Losses from Nonex-
TOTAL
Water
Excavated Leaks:- pn
cavated Leaks:
_ _ _
gPm
Losses: __ gPm
Excavated Leak Nonexcavated Leak
TOTAL
Repair Costs =air
-
Costs Repair Costs
Materials $ Materials $
aterials $
Equipment
$
Labor $ Labor $
Equipment
$
quipment
8
Other $
ther $
Subtotal $ Subtotal
$
-
Labor
$--
Other
$
TOTAL
$
-
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LEAK D ETECTION AND REPAIR PROJECT SUMM ARY
Page
2
of
2
Leak Detection Project Cost Effectiveness
1 .
Calculate the value of water recovered ( V w r ) from a l l repaired
leaks.
= (Total leakage recovered i n gpm)(Conversion Factor) (Water cos t , Wc)
= 1
gpm fo r
2
years 3.23 acre-feet
=
L i n e
19
of Water Audit Report water purchase pr ice
+
operating costs
per u n i t of water
=
( gpm) (3.23 acre-feet/gpm) ( $ / a c r e - f e e t )
vwr = $
Determine the total cost of the leak detection survey.
.........
eak Detection Equipment $ _
Leak Detection Training
$
-
.........
Leak Detection Survey
Costs
......
$
COST of Leak Detection Survey
(B:C) equals:
$
Divide V w r from Step 1 by the total costs calculated i n Step 2.
Value of Water Recovered
Total Cost Leak Detection Survey
B:C
mile.
4. Determine
average survey costs per mile of main surveyed ( C / M ) .
C/M Total Cost of Leak Detection Survex $
Total Number of Miles Surveyed
141
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POTENTIAL REVENUES FROM RECALIBRATED LARGE METERS
Date:
gency Name:
One may estimate revenue gains l i k e l y
from
customers with la rge
meters
found t o .
be
operating in accura tely (slowly or f a s t , but not broken).
records for
the
customer for
the
en ti re audit period should be ava ila ble t o
best
estimate the benefits .
-- --
The metered use
To ca lc ul at e
the
corrected
metered
volume
(CMV)
use the following formula:
_
UMV
(0.01 RE )
MV =
UMV
(Uncorrected
Metered
Volume)
is the
volume of water registered on
t h e
meter (from the bil l ing records), RE (Registration Error) is
the
meter
accuracy in percent, and 0.01 is a conversion fa ct or t o change percentage
t o a decimal.
For Example:
(Registration accuracy
determined
by meter tests) .
U W =
10,000 cubic feet (from bi l l in g records).
RE is 75%
CMV = 13,333 cubic feet
U N CO RRE CT E D CH RGES
CORRECTED CHARGES FOR
INCREASED
METERED BILLED
METERED
CORRECTED
REVENUES
( 1 ) VOLUME 12 months
VOLUME
VOLUME $
METER I D
(UMV) $
(CMV)
12 months (Col 5)-(Col 3)
I
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i
t
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Department of W ater Resources Headquarters Office is at 141 6 Ninth Street, P. 0.Box
acramento, CA 94236-0001,916/653-5584; with District Offices at:
Northern District
2440 Main Street
P.
0.Box 607
Red Bluff, CA 96080
Extension 262
San Joaquin District
3374 E. Shields Avenue
Fresno, CA 93726
9161527-6530
2091445-5262
Central District
3251 S Street
Sacramento, CA 95816
9161323-4891
Southern District
770 Fairmont Avenue
Glendale, CA 91203-1035
P.
0.
BOX
29068 (91209-9068)
8 181543-4600
n Water
Works
Association, Califomia-Nevada Section, is
at
475 South Arrowhead
H, San Bemardino, CA 92408; 714/888-7468.
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Stde
of
Califomia-Resources Agency
Department
of
Water Resources
P.
0 BOX
942836
Sacramento,
CA 94236-0001