Water and Effluent Treatment Magazine
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18 WET NEWS SEPTEMBER 2014 Marais Stream pumping station: Filter screens and pneumatically operated penstock driven by linear actuators to isolate flow, located in the incoming channel Pumping station upgrade keeps the floods • If Marais Stream pumping station in Guernsey had not gone through an upgrade a bank and insurance company would have flooded. TECHKNOW • Three pneumatically operated penstocks have been installed. These are driven by linear actuators to isolate the flow; these were located in the incoming channel • DNC cylinders with rod clamps control the raising and lowering of the penstocks, distributing the incoming water into the storage basins • Festo's CPX remotely operated control system runs the entire system. the CPX platform can operate as either a self-contained industrial PLC, or as a local unit on a Fieldbus or Industrial Ethernet- based distributed system NEED TO KNOW 1 The pumping station is part of a network of facilities that form Guernsey Water's infrastructure for the catchment, storage and transfer of raw water for the production of the island's drinking water 2 Pneumatic control delivers energy saving, ease of installation, safety and reliability, because of less moving parts, as well as being faster to operate and easier to control. 3 Unusual for the water treatment sector is the selection of pneumatically controlled valves rather than electric 4 Heavy rain fell throughout much of February 3, with Guernsey Airport having recorded 32.5mm of rainfall PROJECT SPECS • Upgrade Marais Stream pumping station was originally, which was built in 1938 • Supply and install three pneumati- cally operated penstocks, driven by linear actuators, to isolate the flow • Supply and install a control system that can be remotely operated via the SCADA system from the Guernsey Water offices nearby THE VERDICT "Without a doubt we would have suffered big issues this winter with the heavy rainfall if we hadn't undertaken the work there I can guarantee that there would have been problems if we hadn't upgraded it. "We don't actually have rivers in Guernsey they are all classified as streams; the Marais Stream has a fair catchment area and it includes a bank and an insurance company, and without this work they would have been flooded" Andy Benstead, water production manager at Guernsey Water ONSITE FLOOD MANAGEMENT M uch like the mainland UK, Guernsey has been ravaged by the forces of nature this year. But thanks to a remotely controlled, pneumati- cally operated pumping station that was completed last year, one area of the island has escaped damage from the resulting floods. In February Guernsey faced one of its wettest and windiest days in recent memory. Heavy rain fell throughout much of the day and by the evening Guernsey Airport had recorded 32.5mm of rainfall, flooding many of the island's major roads, making several impassable and causing widespread disruptions. Both local radio stations were forced off air as the FM transmit- ter was flooded, with TV signals being unavailable for part of the night. According to Guernsey Police more than 60 roads were flooded – which outpaced the number of closed signs availa- ble. Sandbags also ran short as authorities scrambled to contain the worst of the weather. But thanks to improvements at the Marais Stream pumping station one area of the island emerged virtually unscathed from the onslaught. The pump- ing station, situated off Les Banques not far from the capital of Guernsey, St Peter Port, is part of a network of facilities that form Guernsey Water's infra- structure for the catchment, stor- age and transfer of raw water for the production of the island's drinking water. "Without a doubt we would have suffered big issues this win- ter with the heavy rainfall if we hadn't undertaken the work there," Andy Benstead, water production manager at Guernsey Water says. "I can guarantee that there would have been problems if we hadn't upgraded it. "We don't actually have rivers in Guernsey they are all classi- fied as streams; the Marais Stream has a fair catchment area and it includes a bank and an insurance company, and without this work they would have been flooded." Flooding problem The work at the pumping station was an upgrade; the whole infra- structure was changed apart from an old tank that remained. "There were two reasons for the upgrade, part age and part because the area had suffered from a flooding problem," Ben- stead adds. "The equipment is much bigger, more reliable, eas- ier to control and we can now pump up to 1,000 litres a second." Marais Stream pumping sta- tion was originally built in 1938 and required an upgrade to allow an increased volume of water to be collected and deliv- ered to the nearby water treat- ment works with less going to waste. Geomarine, a local civil engi- neering contractor, was con- tracted by Guernsey Water to carry out these improvement works as part of ongoing works on the island's infrastructure. Before the project was started all that was on site was a holding tank and pump house. Marais Stream collects the run-off water from the local area and this is fed via the three inlet penstocks through fine screens that remove debris that would damage the pumps in the pump- ing station. The water is then pumped either into the treat- ment works or, in the case of heavy rainfall such as earlier this Pumping station upgrade keeps the floods