Addressing Critical Water Supply Issues Using An Intensive Demand Management Strategy
Author 1 (Paul, Ransom)
Torres Strait Island Regional Council Author 2 (Samantha, Guy)
Torres Strait Island Regional Council
Abstract
This paper aims to demonstrate how a demand-focused strategy using the very latest technologies can lead to significant cost reduction and provide a more stable and sustainable drinking water supply, especially in small scale and remote potable water schemes.
The paper tells the story of the water supply network at Murray (Mer) Island in the Torres Strait. The unique challenges posed by this remote and beautiful corner of Australia have led to a legacy of substandard water supply network conditions and severe water restrictions for the local community.
By implementing an intensive demand management strategy incorporating smart technologies, Artificial Intelligence and implementing calm water network strategies, water demand on Mer Island has been brought back to a sustainable position.
From September 2020 to April 2021 a series of improvements to Mer Island’s supply/distribution network have been made. These include,
• Installation of domestic smart water meters
• Installation of in-situ acoustic hydrophone sensors for leak detection with Acoustic Artificial Intelligence reviewing noise profiles and confirming leaks or identifying false positives
• Installation of the closed loop controllable pressure reduction valves in the water supply network, to promote a calm network strategy
• Utilisation of handheld acoustic leak detection equipment, and
• Utilisation and training of the Council’s ‘on ground’ Engineering Officers and Technical Officers to actively search for mains and domestic water leaks identified by the acoustic fleet and confirmed by the AI analysis platform
As a result, the community on Mer Island have - for the first time in over 20 years* - been lifted off severe water restrictions whereby water supply was only available for 6 hours per day. The reliance on costly desalinated water has been considerably reduced and thanks to use of smart technology and artificial intelligence, demand issues can be detected early and rectified before they develop into more serious problems that threaten the community’s water supply.
Although the conditions and challenges faced on Mer Island are somewhat unique, many are common to other remote Australian communities; many of the techniques used as part of this intensive improvement program could possibly be applied to other remote, small-scaled water supply scheme across regional Queensland and the rest of Australia to save costs and improve the sustainability of water supply.
Keywords: Demand Management, Leak Reduction, Remote, Smart Technology, Calm Networks, Artificial Intelligence
Introduction
Located as the most northerly stretch of Queensland, the Torres Strait Region represents a unique location characterised by specific geographies, cultures, customs, and lifestyles. Mer Island is located within the eastern cluster of the Torres Strait Region which is also referred to as the Kemer Kemer Meriam Nation, and is one of 14 islands serviced by Torres Strait Island Regional Council (TSIRC). Mer Island is home of the 8 tribes of the Meriam people; the Komet, Zagareb, Meuram, Magaram, Geuram, Peibre, Meriam-Samsep, Piadram and Dauer Meriam and has a recognised Native held in trust by the Mer Gedhem Le (Torres Strait Islander) Cooperation RNTBC.
As a remote community, Mer Island has experienced ongoing and broad challenges associated to the growth of the region, resulting in lower service provision standards compared to more densely populated regions. This is a common symptom associated with remote communities in Australia and leads communities experiencing struggles with accessing safe and reliable drinking water (Beal et. Al.
2020). This paper outlines the intensive demand management approach adopted by TSIRC to alleviate the severe water supply issues affecting the residents of the Mer Island community for the past 20 years. It is intended to demonstrate opportunities for other small and remote water supply scheme to address ongoing challenges and improve water management.
Figure 1: Mer island aerial
Mer Island Water Scheme
The Mer Island Water Scheme supplies potable water for approximately 453 residents. Potable water is predominately captured during the wet season rainfall to be stored within a 20ML covered lagoon.
The water supply is supplemented by three permanent reverse osmosis (RO) units that can each produce 70kL/day. During the year is it typical for all RO units to run to ensure suitable water demand is met. Additional storages prior to distribution include two elevated water reservoirs which are in proximity to two separate community areas including a total of 137 connections. The focus of the efforts to reduce water losses and demands have centred on the community area located along the coastline of the island which has older infrastructure and operates at a significantly higher pressure.
While the second community area is located further inland and has relatively newer network. In recent years, additional mobile RO units have been installed as a temporary means to slow the rate of the lagoon’s level drop during the dry seasons.
Figure 2: Mer Island Water Scheme Schematic
Water Security Challenges
For many years, the water supply on Mer Island was overwhelmed by significant water losses leading to severe water security challenges. The costly RO production operations were unable to supplement water storage levels due to the rate at which water was being lost. This has led to the Mer Community’s access to potable drinking water being restricted to the hours of 7-8:30am, 12-1pm, 4- 7:30pm (totalling 6 hours of supply per day) since prior to the formation of TSIRC (for over 10 years).
As an emergency reaction, a 190kL mobile RO unit was stationed on Mer until it was relocated in late 2019. The below table highlights the lagoon level trends between July 2018 and July 2020 against the average usage in litres per person per day.
Figure 3: Mer Legoon level and average consumption from July 2018-July 2020
The issues however were not just associated to the ongoing water losses, indeed the additional contests linked to the remoteness were contributors to the engrained supply issues. For example, there was limited access to accurate infrastructure drawings and high uncertainty regarding the condition of the water mains. The poor condition of the mains was the assumed root cause of the significant water loss in the network, leaks were assumed to be as significant as 5 L/s to 6 L/s (estimated by the rate of drop in the main reservoir level when supply was open). Historically, the water supply lagoon rarely achieved a volume greater than 50% and the restrictions made minimal impact in increase storage levels.
The limited visibility of the network configuration meant determining the locations of leaks when conducting isolation testing was not an easy task. Without a clear idea of where infrastructure was located and operating under the assumption that the water mains were of poor condition when commissioned, issues were largely unknown and could not be pin pointed or appropriately rectified when they arose. The communication barriers in relation to working remotely also factored into inability to rectify issues in a timely manner. The issue was also compounded by high network pressures (over 5 bar) in an area of mostly domestic consumption.
Several environmental challenges also contributed to the water supply issues. Due to highly seasonal rainfall, the large storage lagoon’s ability to capture rainfall was limited to only the wet season (roughly from December to April). With the change of season each year resulting in minimal rainfall during the middle of the year, water demand/losses continuously drained the storage levels.
With the water leaks assumed to be as high as 6L/s, the ongoing cost of water loss is a significant challenge related to the water security issues on Mer Island and another ongoing battle. Approximate calculations revealed in the table below demonstrate the significant costs attributed to the water loss.
100% 750
80%
500 60%
40%
250 20%
0% 0
Jul-18 Oct-18 Jan-19 Apr-19 Jul-19 Oct-19 Jan-20 Apr-20 Jul-20 Monthly Lagoon Level (%)
Average Usage L/P/D
Usage (L/P/D)
Lagoon Level (%)
Cost of generating RO water supplied & cost of water lost Permanent RO (connected to mains power)
• Approx. cost $9/kL
Therefore based on permanent RO operating costs, for a 1L per second leak roughly equates to $778/day
Emergency/mobile RO (powered by genset)
• Approx. cost $19/kL
Therefore based on emergency RO operating costs, for a 1L per second leak roughly equates to
$1728/day
The Approach
The following improvement projects reflect the dedication of many committed individuals from TSIRC Water Operations and Engineering teams who worked alongside specialised service providers to achieve a positive result for the Mer Community. The intensive demand management strategy adopted includes the utilisation of multiple technologies as outlined below, with funding source acknowledged.
• October 2020 – Installation of Acoustic Sensors and Pits with artificial intelligence analysis (Funded by COVID W4Q)
• November 2020 - Smart Meter Installation (Funded by LGGSP) & Leak Detection Investigation (Funded by COVID W4Q)
• December 2020 – Commissioning of Break Tank Water Meter (Funded by COVID W4Q)
• March 2021 – Installation of next gen Pressure Control Valves and advanced pressure control systems and a second sweep for leaks undertaken (Funded by COVID W4Q)
Acoustic Leak Detection
Initial leak detection investigations commenced through the incorporation of in-situ acoustic leak sensors (Hydrophones) in the water network. Figure 3 below displays the location of the acoustic sensors distributed within the coastal community area of Mer Island. These sensors were used to assist in pinpointing approximate locations of leaks on the watermain. Overnight analysis of leak noise profiles is carried out using Artificial Intelligence reviewing sound files from the acoustic sensors which allows for a high level of confidence on sound files and leak sizing Handheld acoustic sensors were also purchased and were used to undertake intensive leak detection works as a follow up to the locations provided by the sensor network.
Figure 4: Map of in-situ hydrophones installed on watermains
Figure 5: AI Analysis confirming leak locations and filtering of noise files
Smart Water Meters
In November 2020, leak detection using smart water meters commenced. Replacing all the old water meters with smart meters aimed to increased visibility of where water supplies were being used within the community. It was found that the most significant leaks in the network were at domestic ferrule connections or after the domestic water meter. High usage and leaks past the meter can now be pinpointed to the property and addressed within 24 hours of the issue arising. Smart meter installation has played a vital role in the reduction of demand and losses within the Mer water network.
Figure 6: Smart Meter install and re-running of property service lines
Flow Meter for Main Reservoir Outflow
Many of the challenges experienced in managing the water supply network relate to the accuracy of the data available for remote monitoring. The installation of an additional flow meter to monitor network supply was essential to provide better visibility of the flow to the main community.
Pressure Control
Pressure valves have been installed at critical locations in the supply network. This equipment helps to address high pressures in the distribution network that impact the condition of the network and increase the likelihood of leaks occurring. The installation of PRV`s require little maintenance and have low head loss capabilities enabling the water network to operate in a more serene manner which reduces stress on the network, two zones were configured to provide closed loop control with critical point pressure logging providing commands to the PRV Controllers to maintain a constant Critical Point Pressure with significantly less pressure fluctuations providing less stress on the network.
Figure 7: TSIRC Technical Officer installing a pressure reduction valve
Figure 8: before and after pressure control with Closed Loop Control at Critical Points
Field Operation Methods
To achieve a drastic change in water loss, targeted field operations were required. The specific field operations refer to the utilisation of the additional technology and artificial intelligence to assist in identifying leak locations and mobilising the local team to detect and repair issues as they were identified.
The Outcome
The combined approach for demand management has proved effective in the short term to eliminate significant water security challenges and ensure water storage levels can be maintained. Continued efforts are needed and will aim to achieve confidence in the water security on Mer Island so there will be less reliance on RO for water production. This presents a positive outcome for the community and provides significant cost savings for the provision of water services.
The onsite leak detection activities revealed that rather than 1 or 2 major leaks, there were many small leaks culminating in significant losses. Leaks were typically located after the residential meters, on the service line between the meter and the water main, or at the ferrule connection to the main.
Contrary to initial assumptions made, no leaks found on the mains themselves. Leak levels (measured using 3am flow rate) from the main town flow meter are now down to 0.5 – 0.7 L/s, which is a huge reduction compared to the calculated loss rate of 5.0-6.0L/s assumed at the commencement of the project.
The installation of pressure valves and pressure controllers has reduced mains pressure 3-fold, from 50m to 15m head, which will significantly reduce the potential for fitting failures and the severity of leaks in the network, reduce transient pressure activity while still maintaining an acceptable pressure to the community.
Today water levels in the lagoon are the highest ever recorded, at approx. 98%, after peaking at 100%
capacity during May 2021. The lagoon has not been full since it was first commissioned over 20 years ago. The below table reveals the lagoon level trend and the increase over the implementation phases of the improvement strategies.
Figure 9: Mer Lagoon Level Trend July 2020 - May 2021
Restrictions have now been lifted and potable water is accessible 24/7 to the community. Constant water supply has an added range of benefits including,
•
The reduction of cyclical loading on the mains (during restrictions, the mains were pressurised and depressurised 3 times every day).
•
Reduced workload of water operators on the grounds creating improved efficiencies as no long need to physically shut off water supply 3 times each day (including weekends).
•
Constant supply will hopefully also decrease the number of water quality compliance issues faced at sampling locations within the distribution network.
MER LAGOON LEVEL TREND 2020 -2021
4,000
Mer Lagoon Level (mm) Lagoon Level Trend Line 3,500
3,000
2,500
2,000
1,500
1,000
500
0
J U L 2 0 S E P 2 0 N O V 2 0 J A N 2 1 M A R 2 1 M A Y 2 1
LAGOON LEVEL (MM)
Since the lagoon has reached capacity, the RO units have recently been shut down temporarily. This will allow much needed maintenance activities to take place on the RO units. We hope to manage the water demand going forward using only the permanently installed RO units and remove the requirement for a supplementary mobile RO unit to operate on the island.
As well as managing the investigation, identification, and repair of leaks by using smart technology to our advantage, in order to prevent a ‘bounce’ effect in the demand, TSIRC hopes to promote ongoing community engagement, education and an increase of data driven communication within council.
Figure 10: Mer Lagoon at capacity (photo taken 10/06/2021)
Ongoing Improvement Opportunities
While several challenges have been addressed through the approaches adopted for the intensive demand management strategy, there are some ongoing improvements that will be required to continue to ensure a sustainable and efficient water scheme for Mer Island. The following actions will continue to be progressed to assist in demand management:
• DMA Water Balancing and the setting of intervention triggers for leak detection
• Migration of asset information to GIS System
• Community Engagement
Conclusion
It must be noted that this report is limited in the information that is supplied. There are several dynamic factors such as the amount of rainfall captured in 2020-2021 wet season, as well as RO production and downtime. These factors prevent the drawing of a firm conclusion that the improvement management strategy outlined in this report is wholly responsible for the increased levels in the lagoon. However, the significant decrease in leaks and demand cannot be ignored.
Although the conditions and challenges faced on Mer Island are somewhat unique, many are common to other remote Australian communities; many of the techniques used as part of this intensive demand management approach could be applied to other remote, small-scaled water supply schemes across regional Queensland and the rest of Australia to save costs and improve the sustainability of water supply.
Acknowledgements
The following TSIRC employees contributed to demand management works.
• Mer Island Engineering Team
• Jerry Marou (Technical Officer) and Ralph Pearson (Technical Officer). Installation of smart meters, hydrophone installation, leak detection and repairs, pressure reduction valve installation
• Goodwill Billy (Technical Officer) and Edward Mosby (Technical Officer).
Hydrophone installation
• Patrick Whittington (SCADA Technician/Data Analyst). Roll out of the smart meters and supporting data management system
• Daniel Harrington (Senior Project Engineer). Managed hydrophone installation, pressure reduction valve, closed loop pressure controller installation, reservoir flow meter upgrade, ongoing leak detection works. Implementation of Acoustic AI (Fido)
The following Service Providers were engaged by TSIRC to assist demand management works by providing specialised equipment/advice.
• Asset Life Alliance. Leak detection training and equipment supply, supply of acoustic sensors, supply and install of next generation low head loss, low maintenance pressure reduction valves. Provision of Advanced Pressure Control Systems, Acoustic Monitoring Artificial Intelligence analysis
• Taggle Systems. Supply of smart meters, radio communication infrastructure and the Aqualus meter data management software
• Austek Pty Ltd. Installation and connection to SCADA of reservoir flow meter. Installation of the radio communication infrastructure for smart meter project
• Northern Water. Supply of ancillary equipment/materials
References
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