A new screen cleaner is helping to protect the environment at one of the country’s oldest schools from the once-frequent impact of flooding. Installed by ECS Engineering over the Daybrook Watercourse that runs alongside the playing fields of Nottingham High School, it prevents weeds and rubbish from building up on a screen restricting access to a culvert.While the Daybrook is little more than a stream most of the time, in wet weather it can rise rapidly and large amounts of debris often washes into it from upstream of the playing fields. This inevitably collects on the culvert screen at the school’s Valley Road playing fields. In the past this would build up and cause flooding unless cleared manually.
“There was the obvious problem of flooding and its aftermath,” say Mick Smith, the ECS engineer who managed the installation. “However, the Environment Agency, which is responsible for the culvert and screen, was also acutely aware of the health and safety risks relating to manual clearing, particularly in extreme weather. For this reason, it commissioned ECS to design and install a bespoke automated screen cleaner.”
Engineering expertise
ECS Engineering Services is one of the UK’s leaders in design, engineering and construction projects for the environment, water, energy, processing and manufacturing industries. It offers a wide range of site services, including total project management for mechanical and electrical installations, civil engineering and construction. It is widely recognised for its track record with water management projects, which include major drainage, flood control and coastal defence systems as well as smaller local projects.
Based in Sutton-in-Ashfield, only a dozen miles from Nottingham, ECS was delighted to undertake the project and quickly had surveyors on site to assess the task ahead of them. Measurements were taken and the water flow gauged; the condition of the existing installation was checked and investigations were made into the type and volume of debris that typically washed against the screen during wet weather.
Mick recalls: “The culvert and surrounding civil structures were in good condition. This meant we could concentrate on designing a screen cleaner that would make use of the existing structures and therefore not be visually intrusive in the wider landscape.”
Optimised design
It was decided that the actual cleaner would be based on a design in which teeth intermesh with the screen and scrape the weeds and debris upwards. At the top, a hydraulic grab activates to deposit the waste into an adjacent skip where it awaits collection and disposal. In fact, the scraper is half the length of the screen, so works in two strokes, left-side and right-side.
“The half-length design was conceived to control the weight of each individual lift, limiting the load to less than half a tonne, If we’d cleared the whole width of the screen in one sweep the weight contained in the debris could have been considerable, we would have needed a much bigger superstructure.”
It was decided to make the screen cleaner fully automatic and capable of autonomous operation. This was because heavy rain and rising water levels in the Daybrook may happen at night, during weekends or school holidays. Furthermore, winter snow and ice build-up are most likely late at night when temperatures are at their lowest.
Staged installation
To this end, water level sensors were installed either side of the screen, both feeding back to a nearby controller which compares the two signals. If the differential exceeds 30 cm, this indicates a build-up of debris in front of the screen and the scraper is activated. It is conceivable that during extreme winter weather the scraper could be activated multiple times an hour, but the system is designed so that this would not overwhelm it.
The project was completed in three stages. “Last autumn, before the wet weather set in, we put up palisade fencing to secure the site. Then we brought in a three-phase power supply, built a small control kiosk and installed the water level transducers. With these in place Landustrie, our water control partner, delivered the screen cleaner straight to site for a fast and efficient installation and commissioning process.”
The equipment has operated perfectly since installation, including during several sudden storms. The local residents are delighted and the school now knows that its sports fields look every bit as smart as the rest of its prestigious campus.
