Holding millions of litres of water at bay by Grindex Submersible Pumps

Grindex Submersible Pumps

When it was decided that new doors needed fitt ing on the four locks a t Trollhättan  on the Trollhättan Canal in central Sweden, the Swedish Maritime Administration turned to Sjuntorp Industrisupport AB for dewatering help. The requirement, to pump 37 million litres of water out of the locks and keep them dry throughout the entire process, was handled by 26 Grindex pumps. After 25 days the project was considered a success and the locks were reopened.

Essential renovation of an important piece of history

When the Trollhättan Canal was opened in 1800, it made the waterways of western Sweden, between the North Sea and Lake Vänern, accessible by sailing ship. Since then the 82 kilometer long stretch of the River Göta, which rises 44 m in total, has gone through a number of major upgrades. The six locks, for example, all have double floors and electrically and mechanically operated doors and gates. Inspections by the Swedish Maritime Administration however, revealed that the gates at the four Trollhätten locks could become a potential hazard. Therefore, on August 25^th 2011, the canal was closed at Trollhättan for essential repairs, including renovation of the locks, changing/upgrading of the lock pumps and installation of the new doors.

Grindex Submersible Pumps

Around the clock pumping

Grindex Submersible Pumps

Each lock, which can house ships up to 4000 metric tonnes, 89 m in length, 13 m wide and 5.4 m deep, typically holds approximately 9500 m³ of water, the equivalent of 9 seconds of water flow in the River Göta. With four locks to empty, powerful and reliable pumps that could operate around the clock were required. The Swedish Maritime Administration, which is responsible for the locks, contacted Sjuntorps Industri Support, as they have successfully handled the dewatering process in the past. With over 300 contractors on site and tight deadlines to meet, it was imperative that every stage of the operation went according to schedule. This of course meant ensuring the locks were kept dry at all times.

Big pumps for a big job

Armed with information from past projects at Trollhättan, staff from Grindex’s technical department assisted Sjuntorps Industrisupport AB with the sizing of the pumps. With 37 million litres of water to be drained before work could get started, 3 slurry, 22 drainage and 1 sludge pump (including stand-by pumps) were recommended, the largest of which can handle 12 m³ water/min.

Work began emptying the locks on Friday night, and by Sunday at around midday the job was completed and work could begin on the renovations. “The drainage pumps were used for the first stage and the sludge and slurry pumps were used to remove the water under the upper floor of the locks,” says Grindex sales engineer, Rolf Mejbert. “This water is quite different to the majority of the water as it’s much denser. Mud, sediment and even quite a lot of fish can be found down there. Fortunately we were able to pump the fish out without harming them,” he concludes.