Water and Effluent Treatment Magazine
Issue link: https://fhpublishing.uberflip.com/i/593898
NOVEMBER 2015 WET NEWS 17 E nnerdale Water in the stun- ning Lake District National Park is owned by United Utilities (UU), which draws from it to supply around 67,000 peo- ple in the immediate region. The lake – designated a Site of Spe- cial Scientific Interest (SSSI) in 2005 – has been a source of drinking water for more than 100 years. It supplies the River Ehen, which supports the largest freshwater pearl mussel population in England. The mussels depend on the presence of thriving populations of salmon and trout, which breed in the river. As a result, UU carefully monitors its work to minimise environmental impact, and has gradually reduced the amount of water taken from Ennerdale over the past two decades. However, a‹er a period of dry weather in 2012 le‹ the Ehen in danger of running dry, it became clear that urgent works were needed to increase the flow of water into the river. Representa- tives from the Environment Agency (EA), Natural England and specialist firm Pontoon- Works worked together on an emergency solution. Pump specialists from Selwood were called in to devise a way of delivering a flow of 60Ml of water daily into the river. Their solution employed the use of a pontoon in the middle of the lake. Three electric submersible pumps were suspended from overhead gantries fitted to the head of the pontoon and con- nected to two 350mm discharge lines via a manifold and non- return valves. There were many complex engineering challenges to be overcome to achieve the goal without subjecting the lake or river to contamination. All pumps and fittings used were stripped, steam cleaned, sprayed with a chlorine solution and bagged prior to use. Selwood provided 740m of plastic pipe- work and fittings, fusion welded to ensure they remained intact in all weathers. Debris Selwood designed and manufac- tured bespoke fish guards around each submersible pump to ensure there was no chance of aquatic wildlife – including fish fry – being sucked into the pumps. All pipework and welding was carefully monitored to ensure that no debris entered the water. Once the pipes were installed, the head of the pon- toon was installed at the far bank on the lake and cabling was installed through a cable duct running down the middle of the pontoon between the pipes. Each pump was connected to When the River Ehen was in danger of running dry, UU and Selwood carried out urgent work to maintain water flow. The challenge: Overcoming dry spells A pontoon was set up in the middle of the lake featuring three electric submersible pumps suspended from overhead gantries INSIGHT PUMPS • THE VERDICT The teams involved kept their focus on minimising environmental impact, working in partnership to balance the needs of people and nature and to secure Cumbria's wild spaces for generations to come. NEED TO KNOW 1 Ennerdale Water is designated a Site of Special Scientific Interest (SSSI) 2 The EA had announced its intention to revoke the abstraction licence for Ennerdale Water by 2025 3 A period of dry weather in 2012 left the Ehen in danger of running dry 4 A flow of 60Ml of water had to be delivered daily into the river THE CONCEpT • The diesel-powered pumps are stored with fuel tanks on drip trays designed to eliminate environmental contamination • A footbridge was utilised for pipework that had to run across a public right of way • This standby ensures river levels are maintained until the permanent new pipelines are installed • Three electric submersible pumps were suspended from overhead gantries fitted to the head of the pontoon a 55kw inverter drive panel so that each could be started at a lower running speed and slowly ramped up to allow the river to adapt to the changes taking place with as little impact as possible. Despite the huge engineering challenges and the short time- scale, the project was a success, restoring water levels in the Ehen and maintaining favoura- ble conditions for the wildlife. The project's ingenuity and execution in difficult circum- stances were widely praised and resulted in a nomination for a Utility Industry Achievement Award. However a number of factors meant that the pontoon, despite its advantages, could not remain as a long-term solution. Among the most pressing considerations was that the EA had announced its intention to revoke the abstraction licence for Ennerdale Water by 2025.