WET News

14 WET NEWS AUGUST 2014 Pumping up the volume • When major refurbishment works were outlined for Abberton Reservoir near Colchester, a water supply pumping solution was needed while the existing pumping station was demolished and rebuilt. TECHKNOW • The temporary pumping station was built alongside the existing one • A purpose-built, floating pontoon, which would house their Flygt submersible pumps, was constructed • The pontoon was anchored in the centre of the reservoir • The level of the reservoir has been raised by a total of 3m, which will eventually lead to a 60% increase in the overall capacity of the reservoir NEED TO KNOW 1 There was just one draw-off level and the available water could have been below that of the station if there was a drought 2 The location adjacent to the reservoir bank made it more susceptible to high turbidity and water quality issues A bberton Reservoir is situ- ated on the outskirts of Colchester in the scenic Essex countryside. It is a large freshwater reservoir covering more than 660 hectares. The reservoir is owned and operated by Essex & Suffolk Water (ESW), part of Northumbrian Water Group, and plays a strategic role in supplying drinking water to 1.5 million people in Essex. Water stored in Abberton Reservoir is pumped 2km to Layer de-la-Haye Water Treat- ment Works (WTW), where it is treated and then distributed to ESW's customers in Essex and parts of East London. During the 1990s it became clear that the predicted popula- tion rise in these regions would substantially increase the future demand for water and as a result, ESW needed to look at viable options to sustainably increase the volume of water stored. The most sustainable option was to enlarge the capac- ity of Abberton Reservoir, and ESW decided to proceed with a £150M investment to ensure that the reservoir could not only cap- ture and store an increased vol- ume of water to help ease demand pressures but also pro- vide a secure supply of water for many years into the future. Footprint The Abberton Reservoir expan- sion incorporated a number of projects including raising the PROJECT SPECS • Build four new dams at Abberton Reservoir • Construct a temporary pumping station • Construct a purpose-built floating pontoon • Demolish existing pumping station • Install four pumps THE VERDICT • Raising the reservoir will eventually lead to a 60% increase in its overall capacity. • The bespoke solution meant that ESW was able to continue supplying the best quality water to our customers while the new pumping station was being built ONSITE REFURBISHMENT height of the main dam by 3.2m, building four new smaller dams around the perimeter of the res- ervoir, raising the B1026 cause- way and moving the highway to accommodate the new reservoir footprint and the construction or refurbishment of a number of pumping stations. In addition, the expansion work also included the huge task of demolishing and recon- structing the main pumping sta- tion, which is responsible for pumping the water to the local treatment works. To enable this to be done, a new temporary pumping station was built alongside the existing station, to enable the continued pumping of water from the res- ervoir. This allowed contractors to demolish the original pump- ing station and build a com- pletely new, raised pumping station, upon the footprint of the original. Construction of the tempo- rary station gave rise to a num- ber of challenges. It had only one draw-off level and, should there have been a drought, the available water could have been below that of the station. Furthermore, its location adjacent to the reservoir bank made it more susceptible to high turbidity and water quality issues. Xylem's rental engineers devised a plan to build a pur- pose-built, floating pontoon, which would house their Flygt The housing for the pumps is put in place on the pontoon, and the pumps are lowered into position

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