Confidently gauging future pressure management performance
Working together with Wessex Water
Richard Barnes,Senior EngineerHydroCo Ltd.
David AcresManaging Director
Richard BarnesSenior Engineer
Martin GansWater Distribution Planning Manager
Jody KnightLeakage Engineer
Tim HattPressure Control Manager
Dr Steve ToomsDirector
Confidently gauging future pressure management performance
2030405060708090
100110120130140150
Leakage (M
LD)
Leakage Reduction ‐ Wessex Water
PROJECT BRIEF / AIMS & OBJECTIVES
• Significant investment in pressure management over the last few AMP periods
• What has this investment achieved?
• How can we measure the performance of the current level of Pressure Management?
• What technologies are available to bring additional improvements to pressure management?
• What impact will these technologies have on our performance measures?
Current leakage level approximately 70 MLD
Wessex Water - Overview
Total modelled properties: 589,260
Customers receiving a pressure managed supply: 355,629
Average Pressure Managed Area Size: 410 properties
Total mains length in models: 11,814 km
Mains length receiving a pressure managed supply: 5,365 km
PROJECT BRIEF / AIMS & OBJECTIVES
Stage 1
Document current WW
Pressure Management
Practice
Compare and contrast
against industry best
practice
Identify a number of
future pressure management
options.
Short term “quick wins”
– support AMP6
Long Term – AMP7
and beyond
Develop Cost Benefit Analysis Model
£ to Reduce AZNP to 40m
Stage 2
£ to Reduce AZNP to 35m
£ to Reduce AZNP to 30m
Measure Scope for additional PM
Measure current
performance of PM using
models
Wessex Water - 33 models - 100% coverage – Good confidence in results
John Coulson manages the Wessex Water model stock, supported by Matthew Price
Models built by multiple parties, with slight variations in methodology
MODEL LIFESPAN
Models Built
PM Review
Rezone
PRV Control Change
New Trunk Main
+Model Update
PM Review
New Commercial
User MainsRenewal Etc. etc.
METHODOLOGY – MODEL UPDATES
Update Modelled Area Codes
• All area codes to conform to same format• relate modelled data to corporate data• apply DMA / PMA codes
Update PRV Controls
• Wessex Water PRV Database• Models vs PRV Controller Database• 250 PMAs Updated
Update PRV Setup
• Stable PRVs in modelling software• Valves operating within 1-100%• Correct Valve Curves & Loss Coefficient
METHODOLOGY
Objective - Measure CURRENT performance of each PMA / DMA
Calculate the following measures using modelled data:
• Total connections• Total mains length• AZNP – Property Weighted• AZNP – Mains Weighted• AZNP – Nodal Point Weighted• Hour to Day Factor• Minimum Node Pressure• Average Node Pressure• Maximum Node Pressure• Minimum Node Elevation• Average Node Elevation• Maximum Node Elevation• Minimum Critical Point Pressure• Critical Point Node Reference• Address of Highest Customer at Critical Node• Maximum Pressure Range (night to peak pressure)• Scope to reduce pressure at night (based on 15m target)• Scope to reduce pressure at peak (based on 15m target)
33 Models1297 DMA / PMAs
862 Pressure Managed Areas=
A lot of number crunching!
METHODOLOGY – SUMMARY OF PERFORMANCE MEASURES
HTD FACTOR (Flow mod scope) (2-stage scope) (fixed scope)AREA CODE TOTAL CONNS MAINS LENGTH AZNP * TOTCON AZNP * MAINL AZNP * NODE AREA HTD NODE_P_MIN NODE_P_AV NODE_P_MAX NODE_Z_MIN NODE_Z_AV NODE_Z_MAX CRITNODE_Z_MIN CRIT NODE MAX NIGHT-PEAK NIGHT SCOPE PEAK SCOPESU164129PA - HOLDERS ROAD 706 4811.31 27.69 26.64 26.48 23.82 14.15 26.30 44.92 74.50 92.09 103.00 14.15 P6312002 2.27 11.48 0.00SU164139PA - LONDON ROAD 363 3324.74 32.45 32.18 31.33 22.74 14.24 29.66 43.23 75.50 86.66 93.25 14.24 P6020005 12.22 16.33 0.00SU164139PC - TOTTERDOWN 136 3719.76 30.98 36.17 33.48 23.95 21.31 33.40 45.55 68.50 79.84 90.90 24.27 H5227001 2.69 18.48 9.27SU203941PA - ALLINGTON 896 19506.30 46.91 47.60 47.87 24.06 27.43 47.99 63.58 59.25 73.79 92.50 27.43 A8773001 3.19 32.87 12.43ST726486PA - SHOPHOUSE ROAD 873 7501.74 37.21 39.01 40.30 22.32 9.62 37.67 63.27 18.50 39.76 60.75 11.53 H2841011 11.36 19.23 0.00ST726505PA - BRASSMILL LANE 244 2019.43 26.30 25.73 26.51 23.95 18.05 26.46 31.01 16.25 20.49 28.50 18.05 P2353037 0.72 18.49 3.05ST726550PA - OSBOURNE ROAD 160 1933.64 24.96 25.61 25.09 23.44 19.28 24.51 29.64 15.00 19.19 23.50 19.28 P2550012 2.44 20.80 4.28ST726761PA - GREENACRES THE MA 44 378.05 23.85 24.99 26.90 24.02 17.31 26.86 63.03 80.29 90.16 96.75 17.31 P2671001 8.70 17.41 2.31ST736292PA - BLOOMFIELD ROAD 592 5753.56 26.85 27.26 25.63 23.96 16.35 25.58 81.63 104.75 160.28 168.15 16.35 H3724009 1.88 17.72 1.35ST736600PA - COOMBE PARK WESTE 1022 7351.93 35.66 34.41 35.69 23.44 15.94 34.74 59.08 16.50 39.64 59.25 15.94 P3063001 5.19 16.22 0.94ST746360PA - ENTRY HILL BATH 190 2043.13 33.15 37.94 35.05 23.13 12.82 33.90 60.00 77.50 100.92 116.25 12.82 P4939004 8.36 19.64 0.00ST746363PA - STIRTINGALE 300 4048.49 33.66 35.79 36.39 23.32 19.14 35.39 52.11 76.50 91.84 106.50 19.14 P4431003 4.10 21.81 4.14ST746499PA - NEW BOND STREET B 370 2433.45 32.71 35.19 37.06 24.04 21.67 37.12 47.05 18.75 28.16 43.00 21.67 P4952041 1.58 22.22 6.67ST746577PA - SHRUBBERY 209 964.39 40.14 36.27 34.87 23.87 11.07 34.70 54.91 64.25 82.92 100.75 11.07 P4757057 7.35 17.07 0.00ST746640PA - SOMERSET PLACE BA 223 2853.01 37.77 37.01 39.83 22.36 9.60 37.46 70.03 68.50 98.02 118.50 9.60 P3961010 10.56 19.33 0.00ST756180PA - MIDFORD SION HILL 8 507.26 68.86 67.93 67.99 24.06 59.09 68.17 76.40 80.75 88.28 96.75 59.09 H5811034 1.32 59.52 44.09ST756204PA - QUEENS DRIVE FOXH 737 4793.96 32.73 34.49 34.47 23.05 20.51 33.16 87.28 102.00 154.45 164.75 21.24 P5024022 4.04 24.17 6.24ST756331PA - PERRY STREET 573 5671.25 40.99 40.63 40.10 23.86 33.95 39.87 64.14 139.50 162.63 165.25 34.17 P4923017 4.87 37.51 19.17ST756419PA - BRIDGE ST BATH 484 2174.41 30.31 30.21 30.68 24.01 23.42 30.69 36.51 17.75 22.68 28.75 24.64 H5653009 2.20 24.55 9.64ST756507PA - ST STEPHENS ROAD 152 791.20 27.13 28.43 28.91 23.86 19.56 28.74 46.58 58.25 75.69 83.50 19.56 P5361016 1.79 21.01 4.56ST756635PA - FAIRFIELD PARK RO 86 927.59 26.28 20.67 20.40 24.06 10.28 20.44 41.01 64.00 84.46 94.50 10.28 P5167002 0.23 10.36 0.00ST756636PB - FAIRFIELD PARK RO 274 1825.90 29.04 25.92 24.21 23.90 10.16 24.12 48.79 56.00 80.55 94.41 10.89 P5366062 0.24 10.36 0.00ST756645PA - MALVERN BUILDINGS 35 179.66 49.51 48.89 41.55 24.19 36.65 41.86 62.59 65.75 86.13 91.00 36.65 H5465022 0.70 36.67 21.65ST756685PA - WROCESTER BUILDIN 26 186.95 42.41 42.15 41.24 23.96 38.36 41.17 44.14 37.25 39.84 42.25 38.36 H5864004 0.78 38.83 23.36ST757181PA - MONKWOOD RES 11 5037.87 62.95 67.42 61.36 23.93 22.22 61.21 93.60 48.75 80.41 118.25 22.22 H5811031 2.47 24.00 7.22ST766435PA - BATHWICK HILL NO1 25 527.63 40.81 41.60 40.47 23.96 25.77 40.41 56.25 81.00 96.57 111.00 25.77 P6345004 0.49 26.04 10.77ST766438PE - SHAM CASTLE TANK 0 51.64 26.07 26.78 23.89 15.84 26.65 32.85 112.00 117.98 128.75 1.13 16.04 0.00ST766473PA - BATHWICK HILL NO2 27 952.63 47.01 43.83 45.42 23.85 22.77 45.17 60.69 106.50 121.74 144.00 28.61 P6643008 0.62 23.20 13.61
NODE PRESSURE DATA NODE ELEVATION DATA CRITICAL NODE PRESSURE DATAAZNP DATAAREA DATA
SQL CREATES MODEL
RESULTS CSV FILE
CSV IMPORTED & PROCESSED
IN SPREADSHEET
(MACROs)
PROCESSED RESULTS SUMMARIESED BY DMA / PMA
Leakage Levels on a DMA
Basis
Burst Frequency on a DMA Basis
RESULTS
Average Zone Night Pressure (AZNP) – For whole company area• Customer Weighted AZNP 40.52 m• Mains Weighted AZNP 46.71 m• Node Weighted AZNP 42.57 m
Average Zone Night Pressure (AZNP) – For pressure managed areas• Customer Weighted AZNP 38.06 m• Mains Weighted AZNP 41.61 m• Node Weighted AZNP 39.86 m
0.005.00
10.0015.0020.0025.0030.0035.0040.0045.0050.00
AZNP CUSTOMERWEIGHTED
AZNP MAINS WEIGHTED AZNP NODALWEIGHTED
AZNP (m
)
Average Zone Night Pressure ‐ Summary
ALL NETWORK PMA NETWORK
RESULTS
Average Zone Night Pressure (AZNP) – PMA / DMA
RESULTS
Hour to Day Factors
Whole Company Area average Hour to Day Factor: 23.50 (e.g. avP 42 & AZNP 43)Pressure Managed Area average Hour to Day Factor: 23.48
Ignoring a few outliers, minimum HTD Factor: 18.37 (e.g. avP 33 & AZNP 43)
00:00 06:00 12:00 18:00 00:00
HTD ‐ Typical Pressure Profile
22.5 24 24.5
1. Optimise existing fixed outlet control pressures
2. Install new pressure management controller2 stage day/night / Flow Modulation / ‘Intelligent’ self adjusting
3. Using Rezoning & Sub-divisionCascading PMA systems or dual PMAs
5. Identifying new PMAsGravity fed systems that can be pressure managed.
ADDITIONAL SCOPE FOR PRESSURE MANAGEMENT
00:00 06:00 12:00 18:00 00:00
00:00 06:00 12:00 18:00 00:004. Mains Reinforcement
Network restrictions causing inefficient control pressure settings
ADDITIONAL SCOPE FOR PRESSURE MANAGEMENT
00:00 06:00 12:00 18:00 00:00
Target LOS Threshold at Critical
Point
Minimum Scope Score
% z range as AZNP reduction
% of PMAS w ith scope
Resultant AZNP
Reduction in AZNP
Potential Leakage Saving
% Leakage Reduction
Reduction in bursts per
year
15m > 0m 5m 72% 37.358m 5.212 4.588 6.60% 21.85
15m > 0.5m 5m 70% 37.361m 5.209 4.575 6.60% 21.8
15m > 1m 5m 68% 37.368m 5.202 4.56 6.60% 21.75
15m > 2m 5m 64% 37.408m 5.162 4.484 6.50% 21.2
15m > 5m 5m 51% 37.735m 4.835 3.786 5.40% 18.9
15m > 10m 5m 32% 38.644m 3.926 2.367 3.40% 13.42
1
2
3
4
5
3
3.5
4
4.5
5
5.5
30% 35% 40% 45% 50% 55% 60% 65% 70% 75% LEAK
AGE RE
DUCT
ION (M
LD)
AZNP RE
DUCT
ION (m
)
% of PMAs for pressure controller optimisation
Benefit of Fixed Outlet Optimisation on existing PMAs
AZNP REDUCTION LEAKAGE REDUCTION
• SCOPE = Achieve a Critical Peak Pressure of 15m (PMAs)
• majority of the performance gains achieved by focusing on 50% of the existing PMA areas
• Only target areas where minimum scope of >5m used in analysis
• Maximum AZNP Reduction = 4.83m
• Maximum UFW Reduction = 3.78 MLD
• Maximum Burst Reduction = 18.9 bursts per year
1. Optimise existing fixed outlet control pressures
ADDITIONAL SCOPE FOR PRESSURE MANAGEMENT
• SCOPE = Critical Night Pressure - 15m
• majority of the performance gains achieved by focusing on 20-30% of the existing PMA areas
• Only target areas where minimum scope of >5m used in analysis
• Maximum AZNP Reduction = 1.56m
• Maximum UFW Reduction = 2.12 MLD
• Maximum Burst Reduction = 2.22 bursts per year
00:00 06:00 12:00 18:00 00:00
Target LOS Threshold at Critical Point
Minimum Scope Score
% z range as AZNP
reduction
% of PMAS with scope
Resultant AZNP
Reduction in AZNP
Potential Leakage Saving
% Leakage Reduction
Reduction in bursts per
year
15m > 0m 5m 63% 35.696m 2.039 2.901 4.20% 2.73
15m > 0.5m 5m 51% 35.717m 2.018 2.882 4.10% 2.72
15m > 1m 5m 45% 35.748m 1.988 2.83 4.10% 2.69
15m > 2m 5m 38% 35.813m 1.923 2.72 3.90% 2.63
15m > 5m 5m 22% 36.175m 1.56 2.121 3.10% 2.22
15m > 10m 5m 9% 36.763m 0.973 1.182 1.70% 1.66
0.5
1
1.5
2
2.5
3
3.5
0.5
1
1.5
2
2.5
0% 10% 20% 30% 40% 50% 60% 70% LEAK
AGE RE
DUCT
ION (M
LD)
AZNP RE
DUCT
ION (m
)
% of PMAs for pressure controller optimisation
Benefit of Pressure Controller Optimisation on existing PMAs
AZNP REDUCTION LEAKAGE REDUCTION
2. Install new pressure management controller2 stage day/night / Flow Modulation / ‘Intelligent’ self adjusting
ADDITIONAL SCOPE FOR PRESSURE MANAGEMENT
Target LOS Threshold at Critical
Point
Minimum Scope Score
% z range as AZNP reduction
% of PMAS w ith scope
Resultant AZNP
Reduction in AZNP
Potential Leakage Saving
% Leakage Reduction
Reduction in bursts per
year
15m > 0.25 10% 60% 34.7 1.48 2.969 4.30% 3.54
15m > 0.5 10% 47% 34.97 1.21 2.822 4.10% 3.36
15m > 1 10% 30% 35.31 0.86 2.471 3.60% 3.04
15m > 2 10% 17% 35.64 0.54 1.957 2.80% 2.45
15m > 5 10% 6% 35.96 0.21 1.083 1.60% 1.76
15m > 0.25 5% 60% 35.44 0.74 1.485 2.10% 1.34
15m > 0.5 5% 47% 35.57 0.6 1.411 2.00% 1.26
15m > 1 5% 30% 35.74 0.43 1.235 1.80% 1.12
15m > 2 5% 17% 35.91 0.27 0.978 1.40% 0.87
15m > 5 5% 6% 36.07 0.11 0.542 0.80% 0.57
1
1.5
2
2.5
3
3.5
0
0.5
1
1.5
2
0% 10% 20% 30% 40% 50% 60% 70%
LEAK
AGE RE
DUCT
ION (M
LD)
AZNP RE
DUCT
ION (m
)
% of PMAs for pressure controller optimisation
Benefit of optimising using rezoning & sub‐divisionon existing PMAs (10% z range)
AZNP RED LEAKAGE RED
• SCOPE = Max Z Range x UFW Volume
• majority of the performance gains achieved by focusing on 30-40% of the existing PMA areas
• Only target areas where minimum scope >1
• Maximum AZNP Reduction = 0.86m
• Maximum UFW Reduction = 2.47 MLD
• Maximum Burst Reduction = 3.04 bursts per year
3. Using Rezoning & Sub-divisionCascading PMA systems or dual PMAs
ADDITIONAL SCOPE FOR PRESSURE MANAGEMENT
• SCOPE = Max Headloss x UFW Volume
• majority of the performance gains achieved by focusing on 20% of the existing PMA areas
• Only target areas where minimum scope >0.5
• Maximum AZNP Reduction = 0.96m
• Maximum UFW Reduction = 3.446 MLD
• Maximum Burst Reduction = 13.65 bursts per year
556065707580859095
100105110115120125
Total H
ead (m
AOD)
SY679334PA ‐ CHARMINSTER VILLA ‐ HEADLOSS PROFILE
MAX HGL MIN HGL z
Resultant AZNP
Reduction in AZNP
Potential Leakage Saving
(m) (m) (MLD)
15m > 0.25 50% 27% 34.85 1.24 3.791 5.50% 14.08
15m > 0.5 50% 19% 35.13 0.96 3.446 5.00% 13.65
15m > 1 50% 10% 35.48 0.62 2.763 4.00% 12.83
15m > 2 50% 5% 35.79 0.31 1.941 2.80% 2.9
15m > 5 50% 1% 36.03 0.07 0.695 1.00% 1.13
Reduction in bursts per
year
Target LOS Threshold at Critical
Point
Minimum Scope Score
% headloss range as
AZNP reduction
% of PMAS w ith scope
% Leakage Reduction
0.511.522.533.54
00.20.40.60.81
1.21.4
0% 5% 10% 15% 20% 25% 30% LEAK
AGE RE
DUCT
ION (M
LD)
AZNP RE
DUCT
ION (m
)
% of PMAs for pressure controller optimisation
Benefit of optimising using reinforcementon existing PMAs
AZNP RED LEAKAGE RED
4. Mains Reinforcement Network restrictions causing inefficient control pressure settings
ADDITIONAL SCOPE FOR PRESSURE MANAGEMENT
• SCOPE = Achieve a Critical Peak Pressure of 15m (DMAs)
• DMAs can include multiple pressure zones, including pumped systems
• This makes identification of new PMAs challenging using a desktop study.
• Only target areas where minimum scope 20m
• Maximum AZNP Reduction = 1.12m
• Maximum UFW Reduction = 0.54 MLD
5. Identifying new PMAsGravity fed systems that can be pressure managed.
0
0.5
1
1.5
2
2.5
3
0
0.5
1
1.5
2
2.5
0% 5% 10% 15% 20% 25% 30% 35%
LEAK
AGE RE
DUCT
ION (M
LD)
AZNP RE
DUCT
ION (m
)
% of DMAs to apply new PMA schemes
Benefit of creating new PMAs
AZNP Reduction Leakage Reduction
ADDITIONAL SCOPE FOR PRESSURE MANAGEMENT
In a perfect world…. If money were no barrier… and this analysis had no caveats
Leakage could be reduced by up to 17% (57.5 MLD)
Average AZNP could be reduced by up to 22% (9.3m)
Bursts could be reduced by up to 37 per year
STUDY LIMITATIONS
• No consideration given to minimum hydraulic requirement (e.g. needs to fill tank at Xm head)
• No consideration given to tall buildings or special customers etc.
• No consideration given to property elevation (analysis at node elevation)
Model Confidence GradingRed, Amber Green (RAG) Grading
36% - HIGH Confidence52% - MEDIUM Confidence12 % - LOW Confidence
Reduced Confidence Due to ………• Last time the model was updated• Percentage of PMAs / DMAs with critical pressures less than 13m• Throttled valves to calibrate network• Throttled valves to ‘age’ PRVs• Pressure spikes caused by modelling software valve operation
Project Timescale
Project Initiation
Data Collection
Model Setup
Results Processing
Scope for PM
Options
Stage 1 Submission
WW Review
STAGE 1
10 weeks work – 1x Senior Engineer
Project Timescale
Confidently gauging the scope of estimated performance improvements
• Perform 9x detailed studies for each Pressure Management Option (3x High, 3x Medium, 3x Low Scope)
• Use ‘Pressure Related Leakage’ to measure actual reduction in leakage and resultant AZNP
• Liaise with WW to understand impact of tall buildings, customer complaints etc. on detailed study areas
• Upscale detailed study results across whole dataset to generate a ‘real world’ achievable gain
• Feed these final performance gains into the Cost Benefit Analysis model developed by TMC
STAGE 2
Detailed Studies
Cost Benefit Model
Final Submission
Final thoughts
STAGE 2
• The historic trend in leakage reduction suggests ‘saturation’ point has been reached
• Existing WW practice does not fully utilise network modelling to optimise PM
• Model results suggest additional performance gains might be possible (-9m AZNP, -19% UFW)• The stage 2 detailed studies should refine these estimates
• Optimisation of existing valves offer the greatest performance gains – Short Term ‘Quick Wins’
• New technologies, or optimising the network to achieve these gains offer smaller performance gains and come at a far higher cost – Long Term AMP 7 and beyond
• The results of the cost benefit model can steer the PM strategy over the next few AMPs
405060708090
100110120130140150
1995 1997 1999 2001 2003 2005 2007 2009 2011 2013 2015 2017 2019 2021 2023 2025
Leakage (M
LD)
Leakage Reduction ‐ Wessex Water
Short term “quick wins” –support AMP6
Long Term –AMP7 and
beyond
Any Questions?
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Percen
tage Con
fiden
ce in
Results %
Confidence in Modelled Outputs
Aging base data reduces confidence
Model update & verification significantly increases confidence
Unforeseen issues in methodology can cause further reduction in confidence