Blog18 February 2020

Ongoing Hinkley Point C project requires Sykes dewatering solution

The sheer scale of Hinkley Point presents its fair share of challenges, necessitating that the experts at Sykes Pumps oversee the site’s far-reaching dewatering requirements.

One of the difficulties of managing a site of this size and scope, particularly given its coastal location, and proximity to natural water courses, is taking rainfall and tidal surges into consideration. To help achieve this, the lead contractor has divided the vast site into six water managements zones (WMZ) and enlisted the help of Sykes Pumps, to provide the varied pumping solutions required.

One of the first tasks for Sykes was to provide a solution to manage the huge surges in flow caused by the tide during construction of the sea wall.

A spokesperson for the contractor explains: “At high tide we needed to be able to pump 350 litres of water per second away from the site. The best approach for this was a submersible pump designed for high flow rates and high heads, which is exactly what Sykes Pumps provided.

“The provision for each WMZ is based on 100-year storm levels; using data from the last century, we have considered what the worst case scenario would be if rainfall were to be as bad as it has ever been over that 100-year period and we then provided Sykes Pumps with the maximum flow rate requirements based on those calculations.

“Some of the excavations are as deep as 35 metres, which means a lot of water silt and sediment. That’s why water storage lagoons are a critical element of the water management strategy, allowing us to test the water before it’s returned to natural water courses.”

The water pump experts provided 3 x PX30 heavy duty electric submersible pumps capable of pumping 350 litres per second and heads of up to 70 metres. These low-maintenance pumps are simple to install and extremely robust, making them ideal for such a busy site.

With these requirements in mind, the contractor has hired super silenced Super Wispaset 100 4″ diesel pumps and super silenced Super Wispaset 150 6″ pumps from Sykes Pumps, for various locations around the site to pump groundwater and rainwater into ‘dirty’ water storage lagoons.

All the pumps are fully-bunded units to ensure that there can be no oil leaks and many have been provided with dedicated fuel cubes, with daily checks carried out.

Most of the pumps have been provided with a float switch-based control system to ensure that they will always kick in automatically should water levels rise, without running unnecessarily during periods of drier weather. This cuts energy costs and reduces the day-to-day management required.

The company has also bought a number of specially-modified surface mounted electric pumps to manage the ground water in each of the WMZ. These will be used in combination with specialist filtration units, which have been specifically designed to separate suspended solids and sediment from water before it is released back into natural water courses. The cleaned water can then be tested for impurities before being discharged.

A total of 14 modified electric surface mounted pumps for deployment across the six WMZ have subsequently been ordered; seven 22kW units and seven 55kW units. These have been modified to include an automated priming system, converting the units to automatic self-priming pumps. The company has also added ultra-sonic control systems with a control room housed in a container unit for each WMZ. The Sykes Pumps engineer involved in designing and implementing the modifications, Bob Lima, has commissioned each of the pumps and delivered training to the site operatives on managing the control system.

Bob explains: “The control systems mean they are extremely low maintenance and will respond rapidly to water conditions in real time. Each WMZ has been specified with a pumping capacity that meets the maximum 100-year resilience required for the specific location, with automated adjustments to flow rates and rapid start of up of the pumps with automated priming.

“The system also provides fault monitoring and the flow will automatically switch from duty pump to standby in real time if a fault is detected, enabling the on-site team to call our engineers out for a maintenance visit.”

The ultra-sonic controls fitted to the surface-mounted electric pumps work on a Windows-based system that collects weather data and predicts water levels based on rainfall patterns, adjusting the flow rate in-line with water storage lagoon levels.

Concluding, a spokesperson for the project explains: “This is much more than a pump hire agreement because of the size and complexity of the site. In addition to the right equipment, Sykes Pumps has provided us with a consultancy-based service that ensures we have the right solutions in place for different areas of the site and the varying pumping needs of different elements of the construction programme.”