Llangollen Canal is a popular boating branch of the Shropshire Union Canal which is fed from the river Dee. In two places, Chirk and Whitehouse, the canal travels underground through a long tunnel before approaching the network’s greatest feat of engineering, the Pontcysyllte Aqueduct.

As part of a construction programme the Canal and River Trust closed both the Chirk and Whitehouse Tunnel whilst sections of deteriorated brickwork below the water level were repaired.

Water within the Llangollen Canal naturally flows at a high rate, requiring over pumping for the duration of the closure whilst the repair took place. Pump Supplies engineers installed two sets of over pumping to pass forward the flows through each of the tunnels. Pumps were installed to pump at a rate of 35 mega litres per day (equivalent to 405 l/s) over a distance of 450 metres through the Chirk Tunnel and 230 metres through the Whitehouse Tunnel.

As the volumes of water being passed forward had to match exactly, Pump Supplies installed pumps which were driven by variable speed drives with digital flow meters on each line to balance the volumes being pumped. In addition to the pumps, Pump Supplies also installed an additional set of over pumping in the basin of the canal at Hurleston Junction nearby passing forward 20 mega litres of water over a distance of 370 metres.

The overpumping systems were in place for the entire duration of the project, operating continuously with no issues or downtime.