Water Services Network Management Grellan McGrath Steven Blennerhassett RPS Consulting Engineers 1.

Water Services Network Management

Grellan McGrath

Steven Blennerhassett

RPS Consulting Engineers

1

Mizen Footbridge2

World Water Day – 22nd March

“When the well is dry, we know the value of water” – Benjamin Franklin

5

World Water Day – 22nd March

6

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

7

Define / Review Levels of Service


Demand Assessment

Demand Assessment

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



Other Service StandardsLeakage - Economic Level

Fireflows – 8 to 75 l/s depending on area served Service Storage - 24 hr

9

Levels of Service

Network Planning

Current Demand - Water Audit

Demand Assessment

Demand Assessment

10

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

11

Current Demand - Water Audit

Demand Assesment

Network Planning

Demand Assessment

Demand Assessment

Demand Management

Reduce water consumption

Reduce water losses

12

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.

13

Demand Management

Current Demand

Demand Assesment

Network Planning

14



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

15

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

16

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

17

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?

18

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

20

Review

Network PlanningReview & Improve

Review & Improve

21

European Communities (Drinking Water)

(No. 2) Regulations 2007 S.I. No. 278 of 2007

Came into immediate effect on 12 June 2007

Legislation

22

Ensure Quality (Regulation 4)

No. ParameterValue

(no./100ml)

1Escherichia coli (E. coli)

0

2 Enterococci 0

Table AMicrobiological Parameters

Legislation

23

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

16

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

24


3 Acrylamide 0.10

4 Antimony 5.0

5 Arsenic 10

6 Benzene 1.0


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



16



1.5 mg/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


24 PAH 0.1

25 Selenium 10


10





17Lead – until 24th December 2013 25

Lead – from 25th December 2013 10

Legislation

25


3 Acrylamide 0.10

4 Antimony 5.0

5 Arsenic 10

6 Benzene 1.0


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



16



1.5 mg/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


24 PAH 0.1

25 Selenium 10


10





27 Trihalomethanes - Total 100

Legislation

26


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


No. Parameter Value

39 Oxidisability 5mg/lO2

40 Sulphate 250 mg/l

41 Sodium 200 mg/l

42 TasteAcceptable to


43 Colony count 22oCNo abnormal

change

44 Coliform bacteria Zero no./100ml

45 Total Organic Carbon (TOC)No abnormal

change

46 TurbidityAcceptable to


Table C Indicator Parameters

Legislation

27


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


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


No. Parameter Value

39 Oxidisability 5mg/lO2

40 Sulphate 250 mg/l

41 Sodium 200 mg/l

42 TasteAcceptable to


43 Colony count 22oCNo abnormal

change

44 Coliform bacteria Zero no./100ml

45 Total Organic Carbon (TOC)No abnormal

change

46 TurbidityAcceptable to


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

30

Loss of Disinfection Residual

Quality Issues

31


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

32


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.

33


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

34

Loss of Disinfection ResidualLoss of Disinfection Residual

Growth of Disinfection By-products

Quality Issues

35



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

36

Prevention

Remove organic precursors during treatment

Change disinfectant (Chloramines)

Reduce water age in distribution system (quicker turnover)



Quality Issues

37


Growth of Disinfection By-productsGrowth of Disinfection By-products

Corrosion / dissolution

Quality Issues

38




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.

39




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.

40




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



Corrosion / dissolutionCorrosion / dissolution

Growth of Biofilms

42




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

43




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


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





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





Cross connections and backflowCross connections and backflow

Stagnation – Dead Ends





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%


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


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


2 + 2 = 4

5 + 3 = 8

x + y = ?

Asset Data


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

56 | WWW.BENTLEY.COM

56Leakage


57Leakage


58Leakage


59Leakage


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

65

Lead Common Services

Rehabilitation

66

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

68

Water Services Network Management Grellan McGrath Steven Blennerhassett RPS Consulting Engineers 1.

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Transcript of Water Services Network Management Grellan McGrath Steven Blennerhassett RPS Consulting Engineers 1.