Client: Severn Trent Water



   An aeration tank at Crankley Point Effluent Treatment Plant

An aeration tank at Crankley Point Effluent Treatment Plant

Severn Trent Services turbidity trials with remote monitoring

Severn Trent Water is Severn Trent Plc’s largest operation. In the UK alone it controls over 200 water works, 1,000 sewage plants and 3,000 pumping sites. Consequently it is always seeking ways to exceed the continuous market demand for greater efficiencies at lower costs to its customers.

Working closely with services provider, Severn Trent Services, the utilities company gains up-to-the-minute knowledge on products, instruments and technology and is often considered a pioneer of new and improved technologies. The latest investigation into remote monitoring systems is testament to that.

Instruments and monitoring devices are trialed on a continuous basis and are part of Severn Trent Services’ on-going research and development programme.

Crankley Point sewage plant is one of Severn Trent Water’s largest sewage works. Ranking in the top 25, it serves approximately 100,000 people living in the town of Newark.

Currently experiencing problems with varying turbidity, the plant has been chosen as the trial site for a number of turbidity instruments. the instruments measure reflected light within the secondary, biological oxygenation process of water treatment. Turbidity is then correlated.

This process is essential in alerting engineers to process problems that may lead to effluent failure and possible pollution of rivers.

At present all Severn Trent Water sites are monitored by a telemetry system that is between 10 and 15 years old. So it is little wonder that, whilst the telemetry system is being replaced, Severn Trent is looking at alternative methods of monitoring.

  Fig 1: Netrix System Online Showing two applications being monitored, including the turbidity

Fig 1: Netrix System Online Showing two applications being monitored, including the turbidity

“Telemetry is rather cumbersome in the way it processes continuous information,” explains Les Stokes, Senior Process Engineer at Severn Trent Water.

“At present the system polls around the stations overnight and, if you’re lucky, you get the information the next day. But you can’t view live data.”

netrixTM is the latest remote monitoring system to be trialed by Severn Trent Water. Harnessing the Internet’s open standards, it not only enables real-time monitoring of the instruments but also provides quick and easy data acquisition and data logging.

In addition Stokes can not only monitor and assess turbidity levels but also measure the accuracy of the instruments over long periods .

“It is very important that the instruments don’t drift over time,” continues Stokes. “Put simply we don’t want instruments that require continual cleaning and maintenance in order for them to remain accurate.”

  Fig 2: Screen shot showing the levels of turbidity

Fig 2: Screen shot showing the levels of turbidity

Intuitive real time access

Designed from the user’s perspective netrixTM provides the level of control that the water industry especially requires.

Mike Long, Electronics Manager at Severn Trent Services who installed and configured the system explains: “There are many remote monitoring products on the market at the moment but none, that I have trialed, offer the same versatility, functionality and security.”

With this kind of control, engineers are no longer called out to a job unless it is urgent. This brings great savings in time, money and resource.

“What is obvious, and indeed advantageous, is the intuitive nature of the system. All our staff have access to the internet and the navigation of netrixTM is very straightforward. As everyone is already familiar and comfortable with the Internet, there is very little training involved.”

“Downloading reports is hassle free and achieved relatively quickly. It is also very easy to reset the parameters if necessary, which again is very encouraging.”

Les Stokes has worked at Severn Trent Water for over 25 years, and in that time he has seen a great deal of change. “Development within the industry is happening much more quickly now,” concludes Stokes.


Les Stokes, Senior Process Engineer at Seven Trent Water

“Telemetry is very good at alerting an engineer to a situation,” continues Stokes, “but you aren’t always able to see what the problem is. With netrixTM you are able to access the site via a browser and see instantly if the alarm is alerting you to a process issue.”