From Gold Coast Water Slides

Leakage and Pressure Management Strategy for the Gold Coast developed by Wide Bay Water (WBW)

from Gold Coast Water slides

Introduction

• In 2002/03 approximately 10% of potable water supplied was unaccounted for water(UFW)

• Typically, 50% of UFW is water lost throughundetectable leaks

• WideBay Water (WBW) developed a leakageand pressure management strategy for the

Gold Coast

District Metered Areas

• Water supply network to be divided intoDistrict Metered Areas (DMAs)

• Each DMA includes approx. 500-1500connections

• Each DMA preferably fed from one water main

• Flow meter and flow-modulated pressurereducing valve (PRV) installed on feed main

Reducing Leakage in a DMA

• Flow meter allows the quantity of waterentering DMA to be monitored

• During the early hours of the morning, themajority of measured flow is leakage

• Leaks are located using specialised equipmentthen repaired

• DMAs allow new leaks to be identified quicklyand make locating leaks easier

Reducing Pressure in a DMA

• PRV allows the water pressures in the DMA tobe controlled

• Using a flow-modulated PRV allows the waterpressure to vary according to the demand

• This ensures adequate water pressure duringhigh demand periods and for fire fighting,while reducing excessive night time pressures

Advantages

• Reduced consumption due to repair of leaks

• Reduced consumption due to lower pressure

• Reduced water main and property servicebreaks

• Improved customer service

• Longer asset life

• Reduced maintenance and renewals costs forwater mains and property services

Negative Impacts

• Potential problems with internal plumbing,hot water services or irrigation systems due to

reduced water pressure

• Potential water quality problems associatedwith more ‘dead ends’ in the water network

Environmental and Social Impacts

• Benefits associated with deferring or reducingthe need for additional capacity in the watersupply system

• Low cost option

• Negligible energy consumption andGreenhouse Gas generation

Burleigh Waters Pilot Trial

• DMA created which incorporates 3,310connections

• Single water main supplies the area at thecorner of Deodar Drive and Symonds Road

• Flow meter and flow-modulated PRV installedat the same location

• Reduction in background leakage of2.95L/second (0.25ML/day) – 48% reduction to

the minimum night flow in the area

• Pilot trial results significantly better thanexpected at the start of the trial

• Additional water savings due to consumptionreduction are expected but have not beenquantified

Citywide Implementation

• 2 additional pilot trials are to be undertaken inBeenleigh and Eagleby

• Planning phase for Citywide implementationapproved by Council

• 108 permanent DMAs planned for the existingareas of the City (highrise strip to be excluded)

• Future development areas to have water supplynetworks designed as DMAs

Citywide Water Savings

• Conservative estimate of savings for leakageand pressure management adopted in currentwater balance – 20ML/day

• Based on a reasonable estimate of leakage perDMA, extrapolated across existing and futureareas of the City

• Implementation will occur over a period oftime.

• More conservative timeframe adopted than isincluded in current construction plan

• Capital cost to implement in existing areas is$6.5million

• Ongoing costs associated with maintenance,and leakage detection and repair

• Reduced revenue will be offset by reducedwater treatment and asset renewals costs,

and deferral of headworks

Conclusions

• Leakage and pressure management presentsthe opportunity for significant water savings

at low cost

• Suggested that the Advisory Committee adopta conservative estimate in the order of20ML/day to be saved by 2056, and that thisfigure be revised as further informationbecomes available