Case

Cilcain Project - Invicta's Solution for remote Welsh reservoir

92 Meters of Bespoke Spindles and New Valves Installed in just 4 days Invicta designs and installs drainage solution for remote Welsh reservoir.

Cilcain is a small, pretty village in North Wales close to Mold and about 16 miles North West of Wrexham. It sits at the foot of Moel Famau, the highest peak in Flintshire. Above Cilcain are a number of small reservoirs. No longer an active part of the potable water supply in the region, the reservoirs are primarily used for fly fishing.

The valves used to control the level of water in one of the reservoirs needed replacing. Invicta was asked to design and install a solution by William Hughes, the civils contractor on the project.

The principal problem faced by Dan Brown, the Invicta engineer tasked with solving the challenge, was that the plinth on which the valves were to sit was over 40 metres away from the control chamber located on top of the dam wall. The solution was to run two 46m-long control ‘guides’ down from the control chamber to the two multi-turn gate valves.

Invicta had undertaken a similar project in Birmingham (Upper Bittel - pictured right) in June 2018. The chosen solution on that occasion was to fabricate the bracketry and steelwork on site which proved more complicated than anticipated. Feedback from the Invicta site team indicated that for the Cilcain project it would be simpler and more effective to design and fabricate the steelwork at Invicta’s workshops in Maidstone and then transport it to site: rather like a giant Meccano kit.

The civils contractor installed support plinths down the sloping face of the dam wall in line with Dan Brown’s design:

‘My goal was to make the system as straightforward as possible for the Invicta team to install, with as little cutting, drilling or welding as possible on site. The bracketry, stems and guide supports were all fabricated in 304L stainless steel to minimise long-term corrosion. All bushings were in HDPE and laid out alongside the fabrication shop to ensure the connecting flanges on the guides were positioned correctly a safe distance from the brackets and the support plinths. Bolting was A2 stainless steel with Nyloc inserts to ensure nothing could come loose.

The entire assembly was designed in 3D in our SolidWorks CAD programme (pictured right). The use of 3D enabled Invicta to present the design to its client and Welsh Water in a way that all parties could easily visualise.

We worked closely with Welsh Water and William Hughes, using their civils drawings and advising them of the groundworks design, plinth angle and a few unforeseen issues too. Logistics was also a challenge due to the remote nature of the reservoir. The nearest postcode directed carriers to the wrong side of the village, so special arrangements were made to deliver the 6m lengths of spindles, plant and other materials. I attended site to scope it out and take measurements before the engineers arrived and I returned to witness the final testing and sign off; all part of the Invicta Valves service!’

The gate valve operation is straightforward. A T-key is used to turn the spindle via a gearbox. The gearbox has a 3:1 operation which means that 66 turns are required to fully open the valves. The cost and disruption associated with draining the reservoir to undertake the works meant that two 250mm gate valves were installed to ensure there was redundancy within the control system.

‘The chosen approach worked really well with only a minimal amount of site welding needed. Despite the remote location of the reservoir, the installation was completed within four working days.’

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