Siltbuster, the UK’s leading water treatment specialist, has developed and mobilised a large modular water treatment system for Lews Civils as part of its essential infrastructure improvement work at a Welsh Water reservoir near Caernarfon in North Wales.

The work, being undertaken by Lewis Civils, involved drilling, which generated fine rock particles and raised the suspended solids content of the water. Further to this, the pH of the water was elevated because cement and limestone grout was used in and below the reservoir’s retaining wall. Both cement and limestone are a threat to aquatic life, so needed to be treated before the water could return to the environment.

Tankering was initially considered, but was quickly deemed socially and environmentally unsustainable, primarily due to the implications of running many heavy tankers into such a remote part of Wales. In addition, the cost of this type of off-site disposal was prohibitive, with each tanker costing around £1,000.

With this in mind, Siltbuster was called in by Lewis Civils to safely treat the large volumes of high pH and solid-laden wastewater being generated, before it could then be released back into the local watercourse. The solution was a three-stage modular chemical treatment system, comprised of a chemical dosing container, large 30m3 multistage reaction tank and three HB50M lamella clarifiers in parallel. By measuring the water quality parameters at the inlet of the system – total suspended solids and pH – chemicals were only used when necessary. This saved money, increased efficiency and reduced carryover.

This temporary treatment system was deployed and installed in April, during the first national coronavirus lockdown, ensuring the site was environmentally was protected at all times.

John Gregson, Senior Site Manager at Lewis Civils, comments: “This project was located in a National Park and so environmental compliance was of critical importance to us. With the operational period running for several months we were impressed with the responsiveness of Siltbuster. It had the equipment readily available within its large rental fleet and the engineer support was present even during the heavy restrictions. We’re happy to say the weekly inspections of the site by Welsh Water all went well, confirming that the stringent water quality criteria had been met.”

James Baylis, Regional Technical Sales Engineer for Siltbuster, concludes: “At Siltbuster, we provide support to a number of essential services such as the construction, municipal and industrial sectors, meaning we have continued to be operational throughout the pandemic. By adhering to social distancing guidelines and stringent safety measures, we have been able to help support many projects across the UK during lockdown, just like we did at Caernarfon for Lewis Civils.”

For more information about Siltbuster, visit or call 01600 772256.