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Overstrand Water Demand Management Hanré Blignaut & Patrick Robinson 29 August 2017
Presentation Outline• Background: Overstrand Municipality
• Overstrand WDM Strategy
• WDM / Revenue Enhancement Study
• Outsourcing of O&M of Bulk Water Services
• WDM Projects
• Tariffs as WDM Tool
• Public Awareness
• Results to Date
• Acknowledgements
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Overstrand Municipality
Overstrand MunicipalityDemographics:
� 94 500 permanent residents; Hermanus 52 000 � 11 Towns and Villages� Main Economic Drivers are Tourism and Agriculture
Water Sources:� 6 Dams� 16 Boreholes� 1 River and 3 Springs
Water Infrastructure:� 8 Water Schemes� 811 km Bulk and main pipelines� 45 Reservoirs� Total Water Demand 2016/17 = 7 556 Mℓ/y = 20.7 Mℓ/day� Water Losses 2016/17 = 19.1%
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Overstrand WDM Strategy
� WDM is part of the IDP and SDBIP
� Objective is to keep UAW < 20%
� WDM / Revenue Enhancement Study completed in 2017
� Review of WDM Projects
WDM / Revenue Enhancement Study
- GLS Consulting appointed in 2016
- Objectives of the Study:- To analyze Treasury Data in order to identify Billing and Meter
Reading Anomalies (2015/16)- To identify projects to be implemented to promote WC/WDM, in
order to reduce UAW
- Methodology:- Swift Analysis of Treasury Data- Link between Treasury and GIS data- High level review of previous WDM studies for the municipality- Meetings with OM staff
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WDM / Revenue Enhancement Study: Results
WDM / Revenue Enhancement Study: Results- Results:
- Stands with 90% increase or decrease in water demand over the last 3 months compared to preceding 9 months (232 properties);
- Large Water Users > 10 kl/day (84 properties)
- WDM Projects Identified:- Appointment of a dedicated WC/WDM Officer- Improved billing by continued co-operation with Finance- Investigate the sites of large water users to identify potential water
saving measures- Investigate and implement additional pressure management projects- Continue with Pipe Replacement Program (PRP study)- Continue with Water Meter Replacement Program- Refine Zone Water Balancing- Monitor ILI’s per zone- Continue with Leak Detection and Repair- Public and Schools Awareness Campaigns
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WDM / Revenue Enhancement Study: Results
Outsourcing O&M of Bulk Water Services
- Operation & Maintenance of 9 x WTW’s; 5 x WWTW’s; 48 p/s
outsourced to a private operator
- Objectives are Skills development, Asset Preservation, Long Term
Improvement of operations
- 15 Year Contract
- Monthly monitoring of 15 x KPI’s, including water losses in bulk
systems and treatment processes
- Baseline losses were determined for each plant
- Penalties for deterioration against baseline
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Use of Treated Effluent from WWTW’s- Use of treated effluent for irrigation = direct saving of potable water
- Irrigation with treated effluent was implemented at Hermanus & Gansbaai
- 7 x Schools, Golf Course and municipal sports fields in Hermanus
- Maximum of 2 Ml/day of final effluent can be utilized for irrigation
- Applied to DWS for amendment of Hermanus WWTW irrigation WUL for
extended use
- 2017/18 – 2018/19: Stanford WWTW upgrade to include treated effluent
irrigation scheme
- Direct Re-use for potable purposes planned for Hermanus in 2021/22
Use of Treated Effluent from WWTW’s
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Use of Treated Effluent from WWTW’s
0
100000
200000
300000
400000
500000
600000
700000
Potable Water (kl)
Irrigation Water (kl)
Total Water (kl)
Use of Treated Effluent from WWTW’s
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Water Pipe Replacement- Started in 2007 with water pipe replacement
- Replaced about 76 km of pipelines to date (9.6% of network)
- Budget over past 10 years - R 76m
- Started in areas with highest water losses, oldest reticulation, most
frequent bursts, highest risks, urgent master plan requirements
- HDPE pipes (pipe cracking, less joints, less disturbance)
- More valves, fire hydrants and air valves installed
- Budget for next 2 years (18/19 & 19/20) – R 10.4m
Water Pipe Replacement- Pipe Replacement Prioritization Model developed by GLS- Pipe Replacement Potential (PRP) - Likelihood of Failure (LF) and Consequence of Failure (CF)- PRP = LF x CF- Factors influencing Likelihood:
- Factors are assessed for each pipe; rating 0-5- Totaled using weights for each factor to determine LF
Likelihood of Failure Property
Nominal Diameter
Pressure
Remaining Useful Life
Master Plan Item
Failure Frequency
Pipe Material
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Water Pipe Replacement- Factors Influencing Consequence of Failure:
- Factors are assessed for each pipe; rating 0-5- Totaled using weights for each factor to determine CF
Consequence of Failure Property
High cost to consumer due to high pressure
High cost to consumer due to flow
High repair cost
Flooding due to geography
Strategic location
Network redundancy
Water Pipe ReplacementPipe Replacement Potential (PRP) = Likelihood of Failure (LF) x Consequence of Failure (CF)
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Water Pipe Replacement
02468
1012141618
2010/11 2011/12 2012/13 2013/14 2014/15 2015/16 2016/17
Bu
dg
et
(R m
illi
on
)
Years
Overstrand Pipe Replacement Budget
0
100
200
300
400
500
600
2010/11 2011/12 2012/13 2013/14 2014/15 2015/16 2016/17No
. of
Pip
e B
urs
ts
Years
Overstrand no. of Pipe Bursts / Year
Pipe Bursts in the Overstrand Reduced from 480/year in 2010/11 to 265/year in 2016/17
Started Pressure Management
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Pressure Management
- Started in 2012 with the implementation of pressure management
- Implemented pressure management in Stanford, Kleinmond, Betties
Bay and Baardskeerdersbos
- Reduced pressure from average 70m to 35m during the day and 25m
during the night at the critical point
- Total Average Flow & MNF reduced
- Pipe failures & Water losses reduced
- Capital Budget for Implementation = R1.85m
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Stanford Pressure Management
MNF after PRV = 4.8m3/h
MNF before PRV = 12m3/h
Difference = 7.2m3/h
U/S PRV Pressure = 68m
CP Pressure (Day) = 35m
CP Pressure (Night) = 25m
Kleinmond Pressure Management
MNF after PRV = 6m3/h
MNF before PRV = 18m3/h
Difference = 12m3/h
Total Ave Flow Before PRV = 47m3/h
Total Ave Flow After PRV = 30m3/h
Difference = 17m3/h
U/S PRV Pressure = 70 - 80m
CP Pressure (Day) = 35m
CP Pressure (Night) = 25m
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Pressure Management & Pipe Replacement Savings
- Stanford MNF Reduced with 7.2 m3/hr = 63 072m3/a @ R10.24/kl =R645 000/a
- Kleinmond MNF Reduced with 12 m3/hr = 105 120m3/a @ R10.24/kl =R1 076 000/a
- Pipe Bursts in the Overstrand Reduced from 299 in 2015/16 to 265 in2016/17 @ average R6 000/pipe burst = R 204 000/a
- Total Savings = R1 925 000/a
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Change Mindset of Municipal Plumbers
- Repair water leaks as soon as possible
- Don’t scour water network unnecessary too long
- Close hydrants after scour process
- Open and Close all valves after leak repairs
- Keep zone valves closed
- Complete Job card with all necessary detail for feedback to data base
Kleinmond Pressure Management
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Consumer Water Meter Replacement- Completed water meter audit during 2011- Started in 2011/12 with consumer meter replacements- Replace meters older than 8 years- Replaced 10154 meters from 2011- Budget for past 7 years R 21.7m
Leak Repairs & Water Management Device Installations at Indigent Households
- Started in 2011/12 with leak repairs and the installation of water management devices
- Repaired 2881 leaks and installed 1165 water management devices to date
- Operational Budget Used
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Public awareness
24m Consumption Graph on Municipal Bills
Facebook & Twitter
Puppet Shows
Newspapers
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Public awarenessBill Boards
Pamphlets
Bulk and Zone metering and Telemetry
- Water supply area divided into pressure (reservoir) zones
- Reservoir bulk meters connected to telemetry system to record usage
- Properties linked to reservoir zones on financial data base
- Manage water balance in smaller areas
- Pick up leaks or abnormal high usage easier
- Verification of bulk and zone meters done annually
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Gansbaai Pressure (Reservoir) Zones
Reservoir Monitoring
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Reservoir Monitoring
Pipe Burst
Leak Detection and Repair
- Started in 2012/13 with leak detection in the Greater Gansbaai,
Pearly Beach and Betty’s Bay Areas
- Only implemented visual inspection, sounding and correlation
methods because of limited budget
- Most leaks found were at house connections on the main line or at
water meters
- All leaks were repaired immediately
- No major leaks found, but every drop counts
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Leak Detection and Repair
Tariffs as WDM ToolWater Tariffs:- Rising block tariff (6 blocks)- Higher blocks discouraging excessive usageSewerage Tariffs:- Based on 70% of water consumption- Sewerage tariffs also discouraging excessive water usage
R 0.00
R 5.00
R 10.00
R 15.00
R 20.00
R 25.00
R 30.00
R 35.00
R 40.00
R 45.00
R 50.00
0-6kl 7-18kl 19-30kl 31-45kl 46-60kl >60kl
Ta
riff
pe
r k
ilo
lite
r(e
xcl
VA
T)
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Tariffs as WDM ToolWATER TARIFFS
Tariff Code Detail2017/2018 2016/2017
Exclude VAT Include VAT Exclude VAT Include VATW1B CONSUMPTION - HOUSEHOLDS
Normal TariffW1B1 0 - 6 kl per kl 4.50 5.13 4.04 4.60W1B2 7 - 18 kl per kl 10.24 11.67 9.66 11.01W1B3 19 - 30 kl per kl 16.61 18.94 15.67 17.86W1B4 31 - 45 kl per kl 25.57 29.15 24.13 27.50W1B5 46 - 60 kl per kl 33.22 37.87 31.34 35.73W1B6 >60kl per kl 44.30 50.50 41.79 47.64
Restriction Tariff (level 1 restrictions)W1B7 0 - 6 kl per kl 4.50 5.13 4.04 4.60W1B8 7 - 18 kl per kl 13.31 15.18 12.56 14.32W1B9 19 - 30 kl per kl 21.59 24.62 20.37 23.22W1B10 31 - 45 kl per kl 33.25 37.90 31.37 35.76W1B11 46 - 60 kl per kl 43.19 49.24 40.75 46.45W1B12 >60kl per kl 57.59 65.65 54.33 61.94
Restriction Tariff (level 2 restrictions)W1B13 0 - 6 kl per kl 4.50 5.13 4.04 4.60W1B14 7 - 18 kl per kl 16.39 18.69 15.47 17.63W1B15 19 - 30 kl per kl 26.58 30.31 25.08 28.59W1B16 31 - 45 kl per kl 40.92 46.65 38.61 44.01W1B17 46 - 60 kl per kl 53.17 60.61 50.16 57.18W1B18 >60kl per kl 70.88 80.80 66.87 76.23
Restriction Tariff (level 3 restrictions)
W1B19 0 - 6 kl per kl 4.50 5.13 4.04 4.60W1B20 7 - 18 kl per kl 20.48 23.35 19.32 22.02W1B21 >18 kl per kl 88.59 101.00 83.58 95.28
Results
0
2000000
4000000
6000000
8000000
10000000
Wa
ter
De
ma
nd
(Ml)
Years
Overstrand Water Demand (Ml/a)
0
500000
1000000
1500000
2000000
2500000
3000000
Wa
ter
Lo
sse
s (M
l)
Years
Overstrand Water Losses (Ml/a)
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Acknowledgements
- OM WDM Team of Infrastructure / Community Services / Finance
- Council
- Top Management
- GLS, WRP, Worley Parsons, Lyners
Thank You
