Water & Wastewater Treatment

18 | FEBRUARY 2015 | WWT | www.wwtonline.co.uk Project focus: Wastewater networks in weight were required in order to secure a good mobile signal for the upload of the data. Flow calculation challenge The variations in the size and shape of the sewers in the network presented a second major challenge. The pipes vary from 1m to 3.5m in diameter, and while most are around 2-3m below ground, some are as deep as 9m. How- ever, most problematically, not all of the sewers are circular: some have an egg-shaped cross section while others have an even rarer bonnet shape. Dave Walker, commercial director at Detectronic, said that this made calculating the flow rate through the relevant formula - the Manning Flow Calculation – much more challenging and required the company to carry out significant work on adapting its so‡ware. "To calculate the flow rate, you need to take the wetted cross-sec- tional area and multiply that by the velocity," says Walker. "Wetted cross sectional area in a rectangular chan- nel is basic maths, while in a circular channel there is a formula to use the day and night operations, and use portable instrumentation to get a more concrete idea of the velocities and flows involved. The coefficients that we have used for the inclination and roughness of the pipes are based on as- sumptions or old designs, and this will help us calibrate the systems better." EYDAP has invested around €90,000 (£70,000) in the 15 monitor- ing stations so far, and have been sufficiently impressed to order five more. If all goes according to plan, there is scope for an enlarged network of around 100 stations in the next five years, according to Pappas. The data produced from the station is uploaded to a web-based so‡ware platform so it can viewed both in EYDAP's control room and in Detectronic's UK data centre. Alarms notify EYDAP of unusually low or high readings, and Detectronic and Metrica continue to work with the utility to interpret and analyse the data received and co-ordinate the best response. "All data monitored directly from EYDAP SA and the oracle database of EYDAP SA will be continuously updated for historical data purposes," says Walker. "Specific attention has been paid to setting up alarm regimes that are sent directly to EYDAP SA. Whenever the thresholds are exceeded, an alarm is activated and the latest data is forwarded to EYDAP SA Data- base and the Detectronic Data Centre. In normal conditions, the data is sent daily to optimise power usage. "The network of sensors will facilitate monitoring for EYDAP SA and enable the team to predict blockages and improve operational network per- formance," he continues. "To achieve this, they will use our specialist, web- based DetecDataPro platform to access and analyse their data. Web access en- sures that Network Management data are available to each relevant person within EYDAP SA." The network of 15 stations was officially handed over to EYDAP in December. Pappas says that effective teamworking between EYDAP, Metrica and Detectronic, and flexible thinking from all the parties, has been key to the project's success so far. He expects similar projects to be carried out in Greece and says the experience gained of overcoming the challenges involved will stand all the partners in good stead. "It was very challenging for all of us – and very difficult in the beginning – but once you climb the mountain you feel very happy about it," he concludes. which is relatively straightforward. But whenever you start getting irregular shaped channels, you have to work out the geometry of that cross-sectional area and it really takes some quite clever mathematical calculations. "As a manufacturer, we are fortunate that as well as our team of electronic engineers we have a team of so‡ware engineers and were able to do everything in-house." Not being able to access the pipes from inside also placed an additional constraint: while flow level meters can be deployed in such a way that they are not in contact with the sewage, this is not the case for velocity meters. For this reason, the team opted to use a single MSFM 12 Area velocity meter which could be placed in the flow at a more accessible point, and moved periodically to a number of locations. This will provide velocity data which can be used to make the Manning Flow Calculation as reliable as possible. The team will also use portable meters to help fine-tune the assump- tions it has made about the pipes, as Pappas explains. "We will take measurements in 1970's 10R A History of Churchill Controls' Telemetry Development 1980's 30R 1990's 20R 2000's Data_Link 2014 Mega_Link Evolution through Intelligent Design Mega_Link Contact us now for anything you need to know about telemetry: Licence-free Radio, GPRS, Leased Line and to receive a copy of our new Mega_Link product brochure Churchill Controls Ltd 30 Wellington Business Park, Crowthorne, Berkshire, RG45 6LS Tel: 01344 750233 e-mail Mega_Link@churchill-controls.co.uk At each stage of our product evolution we: Listen to our customers Encompass latest technology Design Innovate

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