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Case Study: The ports and water leak detection benefits infrastructure sites case
Aquaworks
Case study – The ports and water leak detection benefits infrastructure sites
PA Energy Metering Water Management / (“the sea port case”)
1. How to automatically monitor water consumption at large buildings + sites
2. The use of gas detection methods in water leak detection
3. Using Cloud based systems in visualising water demand
Overview
Large infrastructure sites such as ports, airports, large shopping centres and industrial estates can suffer from notable water leakage, often without realising that such costs can amount from a few pounds per day to hundreds of pounds per day and also the adverse environmental ramifications from water scarcity. This case study shows how water leaks are identified and located.
PA Energy attends the site and visually verify evidence the possibility customer side leakage reported by the site management.
Port water conservation project
PA Energy since 2007 has been involved with several British Ports located in England to provide automated water consumption monitoring, water demand analysis and water leak detection services. The REDSTS system is providing a platform to provide a 24/7 water consumption tracking, daily automated alerts and ability to verify the water supply bills.
At some ports; PA Energy has deployed several remote monitoring devices which allow the port maintenance team and PA energy staff the ability to view water demand across the site and also sub meters.
Water leak detection monitoring
The REDSTS system on a daily basis collects data that is automatically relayed to the REDSTS instance by Fuze Insight platform where the data is stored securely and then made available to users on demand via the REDSTS portal and also provision of a range of reports.
The visualisations can from time to time indicate notable and significant water leakage; this information is then provided to the port maintenance team who can then take remedial actions to resolve.PA Energy systems have identified significant instances of abnormally high demand as well as leakage and have worked remotely and on-site with the port engineers to find the leakage.
The Concept of utilisation of gas detection to locate water leaks
The pipeline route and location shall be verified by the use of electronic pipeline tracing equipment and acoustic methods. Once the pipeline route and location has been verified, sensitive ground microphones shall be used to detect the presence of underground sound signals and frequencies in the leak detection range. If no sound signals are detected then Hydrogen tracer gas mixed in safe ratio of 95% Nitrogen/5% Hydrogen and housed in cylinders that can withstand 200bar will be injected at a variable pressure of up to 4 bar into the suspect pipeline at a suitable point. Highly sensitive gas analysers will be used to pinpoint the location of gas escaping. Should a leak be located, the location of the leak shall be marked on the ground and its location shall be reported to the company contact as detailed above and a brief report shall be prepared listing the findings.
In order to confirm the Water demand findings, isolation valves are shut by site engineers in consultation with PA Energy engineers and verification undertaken to ensure that no water was passing through the valves and filling the tank. Once confirmed isolation has taken place, the Water meter can be “timed” to determine the exact time taken to pass a unit of water.
There often is no external indication of the pipeline route and this location is vital to allow the electronic acoustic and gas injection / gas detection activities to proceed at a later date.
Considerations with pipe materials in tracing of buried pipe direction
To enable pipeline detection of plastic (MDPE) pipe lengths, the most effective and accurate method of determining the pipe details is to insert a conductive element inside the pipe bore and to energise this conductive element with a known electrical frequency (typically 33kHz but selectable). Typically a Cable Dart trace device is utilised.
The tracer wire is housed on a 100m reel and gradually fed into the pipe in lengths of 1 – 2 – 5 – 10m and traced using a very sensitive frequency detector that provides direction and pipe depth validation. As the process takes place, the pipe direction is marked with a semi-permanent road marker paint, this aids the subsequent gas detection exercise.
On the water network, there was a suitable joint at the point that the blue MDPE piping surfaced at the water storage tank end of the car-park and the joint was opened and the conductive element inserted as can be seen below.
The location of the conductive element and hence the pipe route can now be found using a device that simply picks up electrical frequency and can determine depth / location of the conductive element pipeline which is found can run approximately 1.5 – 3 m meters under the surface although this depth may fluctuate over the run length due to the nature of installation or surface gradient changes over the run length. The location of the pipeline is then marked with survey paint (dots) which allow each point to be tested acoustically and gas analysed at a later point.
Using Gas for Water Leak Detection
Tracer Gas Leak Detection Equipment
A highly sensitive ‘Ground Microphone’ such as the Radio Detection acoustics log is placed at intervals of approximately 1 metre along the determined pipeline location. Readings taken at each point with the water pipeline isolated (no flow) and with the water pipeline reconnected at the water tank connector and pressurised (flow).
If no obvious leak noise readings have been obtained although due to the relatively small nature of some leaks under investigation plus the pipe material (MDPE) being relatively quiet in terms of producing noticeable leak noise, this result was not unexpected.
The Water Network is then isolated at the Water Meter end and specialist ‘Tracer’ gas (95% Nitrogen / 5% Hydrogen mixture) injected under controlled low pressure at less than 4 Bar into the pipeline at the water storage end of the water network.
Following a suitable period to allow water to be displaced by the higher pressure gas through any leakage point and the Hydrogen gas to diffuse through surface materials, each point along the determined pipeline route was tested with a highly sensitive gas analyser to determine whether any Hydrogen gas was present above normal atmospheric conditions.
Conclusion: locating the water leak area
Following the determined path of the MDPE pipeline, a very clear area of concern with high Hydrogen readings can be found.
The area of concern providing distinct, repeatable areas of hydrogen gas detection at levels providing certainty that there is a sub-surface leak in the vicinity. One location is almost directly above the anticipated route / direction of the MDPE pipeline as can be seen in the photo opposite. This location was marked on the ground following repeated tests since the windy conditions on the day were causing the Hydrogen to quickly disburse once it reached the surface. No other points were identified as being suspect during the investigation.
Any reading over 50 ppm (parts per million) will trigger an audible and visual alert on the gas analyser highlighting that a potential leak has been located. Readings were obtained in the hundreds of ppm at the point shown above and its location almost directly on the expected pipeline route would suggest that this is the source of the leak. Moving the sensor a matter of 12 inches away from the area would result in the reading dropping away below alarm levels.
Extremely high Hydrogen gas readings were also detected at two grids along a drainage system route running parallel (approx. 1.5m) from the expected pipeline route and within meters of the suspected leak location.
From the isolations and the Hydrogen Tracer gas injection / detection activities undertaken it is then clear that there are sub surface leak within the area of checks and then action is taken to resolve. Unfortunately due to the nature of any gas / fluid based detection technology, the gas will take the easy route to the surface should the surface be broken in any form. It is clear that the tracer gas can be seen to be bleeding into the nearby drain system at some point and this provides the high readings at the two grid locations identified.
It is then recommended that an initial investigation should be undertaken at the point marked ‘suspected leak’ shown in the previous images. Due to the possibility that there is a small error in the leak location due to gas escaping into the drainage system, it may be necessary to extend the search along the pipeline between the two grid locations showing high gas readings.
Both grid locations were revisited on a subsequent day and readings retaken before Hydrogen was injected. This activity showed that there is no Hydrogen naturally present in the grids due to acid reacting with other materials (cleaning fluids dumped for example).
Following completion of activities, all joints and connectors were remade and lagging was replaced at the point of gas injection.