Post on 29-Mar-2015
Water Services Network Management
Grellan McGrath
Steven Blennerhassett
RPS Consulting Engineers
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Mizen Footbridge2
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World Water Day – 22nd March
“When the well is dry, we know the value of water” – Benjamin Franklin
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World Water Day – 22nd March
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A Brief History of Cork City’s Water Supply
1762 - Cork Pipe Water Company Established
Timber distribution pipes, 20ft long – 2 ½” to 3” ø
1856 - Cork Bridges, Waterworks and Improvement Act
1857 - Cast iron mains introduced – network extended.
1879 – Filter tunnel constructed
1911 - “intense waste water campaign” due to efforts of city engineer and
inspectors reduced consumption from 70 to 38 gal/p/d (172 l/p/d)
1928 – Sand filters installed
1940’s - new high level reservoir built as an unemployment relief scheme
1956 – New filters and sedimentation plant
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Define / Review Levels of Service
Define / Review Levels of Service
Demand Assessment
Demand Assessment
Collect NetworkAsset Data
Collect NetworkAsset Data
Capacity Assessment
Capacity Assessment
Improvement Options
Improvement Options
Management PlanManagement Plan
Financial PlanFinancial Plan
Water Network Management
Water Network Management
8 Network PlanningReview & Improve
Review & Improve
StatutoryWater Quality – SI 278/2007
CustomerService Pressures -15 to 40m Head
Define / Review Levels of Service
Define / Review Levels of Service
Other Service StandardsLeakage - Economic Level
Fireflows – 8 to 75 l/s depending on area served Service Storage - 24 hr
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Levels of Service
Network Planning
Current Demand - Water Audit
Demand Assessment
Demand Assessment
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Demand Assesment
Network Planning
Demand Assessment
Demand AssessmentDistribution
Input
(DI)
Accounted for
Water
(AFW)
Measured or assessed lergitimate water use
Unaccounted for Water
(UFW) = DI - AFW
Domestic Demand
Households x Occupancy x pcc
Non-Domestic Demand
Metered consumption
Operational Use – 2% of DI
Permanent Domestic
Seasonal Domestic
Peaking Factor – Average Day/Peak Week
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Current Demand - Water Audit
Demand Assesment
Network Planning
Demand Assessment
Demand Assessment
Demand Management
Reduce water consumption
Reduce water losses
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Current Demand
Demand Assesment
Network Planning
Demand Assessment
Demand Assessment
Future Demand Population growth (25-Year Horizon)
- Top Down: Planning guidelines, CSO
- Bottom Up: Availability of zoned land
Demand
– Domestic demand as per audit using projected pcc, losses etc.
- Non-domestic demand growth in line with domestic
- UFW in line with level of service objectives.
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Demand Management
Current Demand
Demand Assesment
Network Planning
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Collect NetworkAsset Data
Collect NetworkAsset Data
Asset Data - National Water Study 2000
Length of network (size, age, material, condition, performance) Number/capacity of pumping stations Number and total volume of storage reservoirs Value of total asset (Modern Equivalent Asset (MEA) value) Value of assets to be replaced over next 5 years (MEA value) Annual operating and maintenance costs.
Network Planning
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Capacity Assessment
Capacity Assessment
Asset Capacity Assessment
Design Horizon
Dem
and
/ C
apac
ity
15 - 20 Yrs 20 - 25 Yrs0 - 5 Yrs 5 - 10 Yrs 10 - 15 Yrs
Rated Asset Capacity
Projected Demand Range
Capacity Shortfall
Expected Time Range of Deficit
Network Planning
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Capacity Assessment
Capacity Assessment
Design Horizon
Dem
and
/ C
apac
ity
15 - 20 Yrs 20 - 25 Yrs0 - 5 Yrs 5 - 10 Yrs 10 - 15 Yrs
Expected Time Range of Deficit
Increased Asset Capacity
Rated Asset Capacity
Asset Capacity Assessment
Network Planning
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Improvement Options
Improvement Options
Network Planning
Improvement OptionsAssess Capacity
Requirement
Can it be satisfied byRehab/renewal option?
No
Can it be satisfied byAugmentation Option?
No
Can it be satisfied byUpgrade/Replacement?
No
Yes
Proceed with selected option
Yes
Yes
Yes
Can it be satisfied byOperational Optimisation?
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Management Plan
Management Plan
Management Plan
Asset Inventory – As per NWS
Operational Plan – Summary of primary objectives in the operational plan and any sub-plans
Maintenance Plan – Summary of the planned asset maintenance.
Rehabilitation/Renewal Plan – Summary of the planned asset rehabilitation/renewal activities.
Asset Replacement – Summary of the planned asset replacement.
Network Planning
Financial Planning
Financial PlanFinancial Plan
Operation and Maintenance
Expenditure
Interest Expenditure (if any)
Asset Depreciation
Funding for Historic Under-investment
Funding for Service Enhancement
Funding for System Growth
Funding for Loan Repayment
Just covering
cash costs
Covering cash costs and providing for
maintaining current asset condition – no
planning for the future
Sustainable level of expenditure to cover future
investment needs
Water Services Expenditure Requirements
19 Network Planning
Levels of Service
Demand for Water Services
Asset Management
Finance
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Review
Network PlanningReview & Improve
Review & Improve
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European Communities (Drinking Water)
(No. 2) Regulations 2007 S.I. No. 278 of 2007
Came into immediate effect on 12 June 2007
Legislation
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Ensure Quality (Regulation 4)
No. ParameterValue
(no./100ml)
1Escherichia coli (E. coli)
0
2 Enterococci 0
Table AMicrobiological Parameters
Legislation
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Ensure Quality (Regulation 4)No. Parameter Value (μg/l)
3 Acrylamide 0.10
4 Antimony 5.0
5 Arsenic 10
6 Benzene 1.0
7 Benzo(a)pyrene 0.01
8 Boron 1.0 mg/l
9 Bromate 10
10 Cadmium 5.0
11 Chromium 50
12 Copper 2.0 mg/l
13 Cyanide 50
14 1,2-Dichloroethane 3.0
15 Epichlorohydrin 0.1
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Fluoride (a) fluoridated supplies0.8 mg/l
Fluoride (b) naturally occurring fluoride, not needing further fluoridation
1.5 mg/l
No. Parameter Value (μg/l)
17Lead – to 24/12/13 25
Lead – from 25/12/13 10
18 Mercury 1.0
19 Nickel 20
20 Nitrate 50 mg/l
21 Nitrite 0.5 mg/l
22 Pesticides 0.1
23 Pesticides Total 0.5
24 PAH 0.1
25 Selenium 10
26Tetrachloroethene and Trichloroethene
10
27 Trihalomethanes – Total 100
28 Vinyl chloride 0.5
Table B Chemical Parameters
Legislation
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Ensure Quality (Regulation 4)No. Parameter Value (μg/l)
3 Acrylamide 0.10
4 Antimony 5.0
5 Arsenic 10
6 Benzene 1.0
7 Benzo(a)pyrene 0.01
8 Boron 1.0 mg/l
9 Bromate 10
10 Cadmium 5.0
11 Chromium 50
12 Copper 2.0 mg/l
13 Cyanide 50
14 1,2-Dichloroethane 3.0
15 Epichlorohydrin 0.1
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Fluoride (a) fluoridated supplies0.8 mg/l
Fluoride (b) naturally occurring fluoride, not needing further fluoridation
1.5 mg/l
No. Parameter Value (μg/l)
17Lead – to 24/12/13 25
Lead – from 25/12/13 10
18 Mercury 1.0
19 Nickel 20
20 Nitrate 50 mg/l
21 Nitrite 0.5 mg/l
22 Pesticides 0.1
23 Pesticides Total 0.5
24 PAH 0.1
25 Selenium 10
26Tetrachloroethene and Trichloroethene
10
27 Trihalomethanes – Total 100
28 Vinyl chloride 0.5
Table B Chemical Parameters
No. Parameter Value (μg/l)
17Lead – until 24th December 2013 25
Lead – from 25th December 2013 10
Legislation
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Ensure Quality (Regulation 4)No. Parameter Value (μg/l)
3 Acrylamide 0.10
4 Antimony 5.0
5 Arsenic 10
6 Benzene 1.0
7 Benzo(a)pyrene 0.01
8 Boron 1.0 mg/l
9 Bromate 10
10 Cadmium 5.0
11 Chromium 50
12 Copper 2.0 mg/l
13 Cyanide 50
14 1,2-Dichloroethane 3.0
15 Epichlorohydrin 0.1
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Fluoride (a) fluoridated supplies0.8 mg/l
Fluoride (b) naturally occurring fluoride, not needing further fluoridation
1.5 mg/l
No. Parameter Value (μg/l)
17Lead – to 24/12/13 25
Lead – from 25/12/13 10
18 Mercury 1.0
19 Nickel 20
20 Nitrate 50 mg/l
21 Nitrite 0.5 mg/l
22 Pesticides 0.1
23 Pesticides Total 0.5
24 PAH 0.1
25 Selenium 10
26Tetrachloroethene and Trichloroethene
10
27 Trihalomethanes – Total 100
28 Vinyl chloride 0.5
Table B Chemical Parameters
No. Parameter Value (μg/l)
27 Trihalomethanes - Total 100
Legislation
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Ensure Quality (Regulation 4)
No. Parameter Value
29 Aluminium 200 μg/l
30 Ammonium 0.3 mg/l
31 Chloride 250 mg/l
32 Clostridium perfringens Zero No./100ml
33 ColourAcceptable to
consumers & no abnormal change
34 Conductivity2500 μS/cm @
20oC
35 Hydrogen Ion Concentration ≥6.5 & ≤9.5
36 Iron 200 μg/l
37 Manganese 50 μg/l
38 OdourAcceptable to
consumers & no abnormal change
No. Parameter Value
39 Oxidisability 5mg/lO2
40 Sulphate 250 mg/l
41 Sodium 200 mg/l
42 TasteAcceptable to
consumers & no abnormal change
43 Colony count 22oCNo abnormal
change
44 Coliform bacteria Zero no./100ml
45 Total Organic Carbon (TOC)No abnormal
change
46 TurbidityAcceptable to
consumers & no abnormal change
Table C Indicator Parameters
Legislation
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Ensure Quality (Regulation 4)
No. Parameter Value
29 Aluminium 200 μg/l
30 Ammonium 0.3 mg/l
31 Chloride 250 mg/l
32 Clostridium perfringens Zero No./100ml
33 ColourAcceptable to
consumers & no abnormal change
34 Conductivity2500 μS/cm @
20oC
35 Hydrogen Ion Concentration ≥6.5 & ≤9.5
36 Iron 200 μg/l
37 Manganese 50 μg/l
38 OdourAcceptable to
consumers & no abnormal change
No. Parameter Value
39 Oxidisability 5mg/lO2
40 Sulphate 250 mg/l
41 Sodium 200 mg/l
42 TasteAcceptable to
consumers & no abnormal change
43 Colony count 22oCNo abnormal
change
44 Coliform bacteria Zero no./100ml
45 Total Organic Carbon (TOC)No abnormal
change
46 TurbidityAcceptable to
consumers & no abnormal change
Table C Indicator Parameters
No. Parameter Value
33 Colour
Acceptable to consumers & no abnormal change
38 Odour
42 Taste
46 Turbidity
Legislation
QualityQuantity
QualityQuantity
28 Focus Shift
Factors Influencing Microbial Change in Water Distribution Systems
29 Quality Issues
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Loss of Disinfection Residual
Quality Issues
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Loss of Disinfection Residual
Quality Issues
All water entering distribution systems should be disinfected
Treated water should contain chlorine residual of 0.5mg/L for 30mins contact time prior to supply
Residual should be monitored before entering distribution
Maintain residual of at least 0.1 mg/L at the extremity of the network
EPA Guidance on Chlorination
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Loss of Disinfection Residual
Quality Issues
Rate of Loss
Up to 50% lost during primary disinfection (first few hours)
Rate of loss thereafter reduces significantly and depends on:-
- Temperature - Reactivity of organic carbon in water- Reactivity of Pipe wall – “wall demand”
Half life after primary disinfection can vary from several days to several weeks but can reduce to several hours with high demand.
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Loss of Disinfection Residual
Quality Issues
Use chloramines for secondary disinfection – longer lasting
Pipe flushing, relining or replacement to reduce “wall demand”
Reduce residence times in storage.
Install booster chlorination facilities
Reduce total level of organic carbon in treatment process.
Mitigation
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Loss of Disinfection ResidualLoss of Disinfection Residual
Growth of Disinfection By-products
Quality Issues
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Loss of Disinfection ResidualLoss of Disinfection Residual
Growth of Disinfection By-products
Quality Issues
• Reaction of chlorine with naturally occuring organic matter
• Most common by-products are Trihalomethanes (potential carcinogens)
• Amount of THM production depends on:-- pH
- Temperature- Chlorine dose- Amount of organic precursor- Reaction time
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Prevention
Remove organic precursors during treatment
Change disinfectant (Chloramines)
Reduce water age in distribution system (quicker turnover)
Loss of Disinfection ResidualLoss of Disinfection Residual
Growth of Disinfection By-products
Quality Issues
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Loss of Disinfection ResidualLoss of Disinfection Residual
Growth of Disinfection By-productsGrowth of Disinfection By-products
Corrosion / dissolution
Quality Issues
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Loss of Disinfection ResidualLoss of Disinfection Residual
Growth of Disinfection By-productsGrowth of Disinfection By-products
Corrosion / dissolution
Quality Issues
Contributing Factors
Flow – Stagnant conditions promote tuberculation and pitting in iron pipes. Temp - Rate of corrosion increases with incresing temperature
pH - Lower pH promotes corrosion.
DO - Oxygen promotes corrsion of ferrous metal forming tubercules and “red water” TDS - Increases conductivity promoting electrochemicl corrosion
Bacteria - Bacteria in bioflim can create local changes in pH and DO.
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Loss of Disinfection ResidualLoss of Disinfection Residual
Growth of Disinfection By-productsGrowth of Disinfection By-products
Corrosion / dissolution
Quality Issues
Indicator - Langelier Saturation Index
LSI = pH - pHs
LSI > 0 Water is supersaturated with respect to calcium carbonate (CaCO3) and scale forming may occur.
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Loss of Disinfection ResidualLoss of Disinfection Residual
Growth of Disinfection By-productsGrowth of Disinfection By-products
Corrosion / dissolution
Quality Issues
Control
Make water less corrosive - pH adjustment most common (Typically 8.0
to 8.5).
Lay down protective lining on pipe wall - pH adjustment or
Phosphate addition
Replace pipe with pipe less prone to corrosion.
41 Quality Issues
Loss of Disinfection ResidualLoss of Disinfection Residual
Growth of Disinfection By-productsGrowth of Disinfection By-products
Corrosion / dissolutionCorrosion / dissolution
Growth of Biofilms
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Loss of Disinfection ResidualLoss of Disinfection Residual
Growth of Disinfection By-productsGrowth of Disinfection By-products
Corrosion / dissolutionCorrosion / dissolution
Growth of Biofilms
Quality Issues
Promotion
Growth depends on nutrient
avalability (TOC)
High temperatures (>15oC)
promote greater bacterial activity
Corroded pipes support film
development
Low disinfecion residual
Low / stagnant flow
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Loss of Disinfection ResidualLoss of Disinfection Residual
Growth of Disinfection By-productsGrowth of Disinfection By-products
Corrosion / dissolutionCorrosion / dissolution
Growth of Biofilms
Quality Issues
Reduction
Reduce nutrient avalability during
treatment (reduce TOC)
Optimise disinfectant dosage /
booster chlorination
Flushing
Corrosion control
Mains rehabilitation or replacement
44 Quality Issues
Loss of Disinfection ResidualLoss of Disinfection Residual
Growth of Dinisfection By-productsGrowth of Dinisfection By-products
Corrosion / dissolution Corrosion / dissolution
Growth of BiofilmsGrowth of Biofilms
Cross connections and backflow
45 Quality Issues
Loss of Disinfection ResidualLoss of Disinfection Residual
Growth of Dinisfection By-productsGrowth of Dinisfection By-products
Corrosion / dissolution Corrosion / dissolution
Growth of BiofilmsGrowth of Biofilms
Cross connections and backflow
Backsiphoning Backflow when pressure in main drops (e.g. Surge, excessive flows, pipe bursts, flushing)
BackpressureBackflow when pressure on contamonation side increases (e.g. pressurised heating/cooling systems, industrial systems.
46 Quality Issues
Loss of Disinfection ResidualLoss of Disinfection Residual
Growth of Dinisfection By-productsGrowth of Dinisfection By-products
Corrosion / dissolution Corrosion / dissolution
Growth of BiofilmsGrowth of Biofilms
Cross connections and backflowCross connections and backflow
Stagnation – Dead Ends
Loss of Disinfection ResidualLoss of Disinfection Residual
Growth of Dinisfection By-productsGrowth of Dinisfection By-products
Corrosion / dissolution Corrosion / dissolution
Growth of BiofilmsGrowth of Biofilms
Cross connections and backflowCross connections and backflow
Stagnation – Dead EndsStagnation – Dead Ends
Milky Water
Quality Issues 47
Water Conservation 48
Water Distribution Network Management and Leakage Control
Water Distribution Network Water Distribution Network Management and Leakage Management and Leakage ControlControl
Passive V’s Active
49Water Conservation
Stage Element Central Funding Level
Stage 1 Implementation of Water Management Systems
100%
(records 90%)
Stage 2 Active Leakage Control 100% limited
Stage 3 Rehabilitation 90%
Strategic Plans 90%
50Water Conservation
Dublin Regional Water Conservation Project
Total Savings 7.9 Ml/day
Pipe Rehabilitation - 2.1 Ml/day
Pressure Management - 2.4 Ml/day
DMA Optimisation/Metering - 3.4 Ml/day
51Water Conservation
Asset DataExamples of Raw Data Held• Customer demand (billing information)• Customer complaints• Customer meter locations• Customer surveys• Demand surveys• Facilities failures• Flow and pressure measurements• Inspectors' site reports• Mains and facilities record drawings• Measured leakage and other non revenue water uses and wastage• Meter maintenance/audits• Number of shut valves and operations• Network maintenance reports• Network performance by location• Records of repairs and rehabilitation• Pipe sampling (e.g. cut outs)• Staff training records• Water quality samples by location
Systems and processes used to collate and interpolate data
• Asset data support• Burst records/deterioration models• District Meter Area monitoring• Distribution 0peration Maintenance
Strategies• Emergency plans• Geographic Information Systems• Health & Safety records• Hydraulic, surge and water quality
modelling• Information and models from other
utilities• Job scheduling• Leak management
52Water Conservation
2 + 2 = 4
5 + 3 = 8
x + y = ?
Asset Data
53Water Conservation
UFW = Water produced – Water Consumed
Made up of:-
• Leakage • Incorrect meter readings• Illegal connections• Illegal or unknown use• Waste of water
• Taps left open• Household losses
• Bad plumbing • Tanks over flowing
54Unaccounted For Water
Scenario 2:
Reduce UFW by half
200 m3/day
400 m3/day
600 m3/day
67 %
17 l/conn/hr
833 l/km/hr
Scenario 3:
New Large Non-Domestic Usage
800 m3/day
800 m3/day
1,600 m3/day
50 %
33 l/conn/hr
1,667 l/km/hr
Scheme A Scenario 1:
20 km of mains
1000 properties
AFW 200 m3/day
UFW 800 m3/day
Into Supply 1,000 m3/day
UFW Expressions 80 %
33 l/conn/hr
1,667 l/km/hr
Scheme A Scenario 1: Scenario 2: Scenario 3:
20 km of mains Reduce UFW by half New Large Non-Domestic Usage1000 properties
AFW 200 m3/day 200 m3/day 800 m3/day
UFW 800 m3/day 400 m3/day 800 m3/day
Into Supply 1,000 m3/day 600 m3/day 1,600 m3/day
UFW Expressions 80 % 67 % 50 %
33 l/conn/hr 17 l/conn/hr 33 l/conn/hr
1,667 l/km/hr 833 l/km/hr 1,667 l/km/hr
55Unaccounted For Water
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56Leakage
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57Leakage
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58Leakage
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59Leakage
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60Leakage
Leakage Control
61Leakage
Typical SRELL
0
50
100
150
200
250
300
350
400
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Target Leakage (m3/km/d)
Eu
ro N
PV
('0
00)
Value of water lost
ALC Costs
Total Costs
BLL ELL
Economic Level of Leakage (ELL):-
62Leakage
63Rehabilitation
Lead Common Services
64Rehabilitation
M h
M h
29
48
36
LS
37
LS
H
M hs
LS
42
LS
RO AD
23
4
LS
M h
M hsLS
M hH
M hs
5
16
132
17
18
LS
H
1718
130
129LS
M h
120
Terrac e
67 LS
M h
25
LS
M h
29
12
M h
13
M h
LS
9
LS
8
LS
43
M h
LS
HRO AD
LS
ES
LS
24
25
H
16
2
LS
1
M h
15
M EELICK ROAD
10
LS
78
P O
LB26
LS
30
1
9
114
113
LS
LS
H
M h
108H
109
LS
M hs
48
37
53
49
45
42
9
11
78
LS
5554
LS
13
H
12
Sports Ground
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Lead Common Services
Rehabilitation
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Replacing Lead Common Services
Rehabilitation
Good data is key to sound investment decisions
It is more cost effective to actively manage than to passively manage
Need to manage Water Quality risks associated with the distribution network.
67Key Message
Thank You
Q’s
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