The self cleansing, low-headloss, and cost effective Heliscreen® supplied by Hydro International provided the solution the city was looking for.
A Combined Sewer Overflow (CSO) upgrade project in urban Sheffield, UK demonstrated the versatility of Hydro International’s Heliscreen®. The Heliscreen® was incorporated to aid Yorkshire Water Services, Ltd in complying with the British Environment Agency’s water quality standards in conjunction with their Asset Management Program (AMP) Three spending cycle. AMP3 required water companies to spend an estimated $7.0 billion on nearly 7,000 environmental projects to improve rivers and coastal waters in England and Wales. Most of these projects improved discharges from sewers to water courses.
The goal at the Carlisle Street installation (one of two screen structures on the same site) was to incorporate a screen solution that would prevent aesthetic pollutants from being discharged into a nearby watercourse. The intention was install this screen solution in an active regulator structure while minimizing the civil work to the structure as it was situated below an active highway. Yorkshire Water identified that the Heliscreen® would be the best alternative to reduce the discharge of visually offensive material because of its low headloss, capacity to operate under tailwater conditions and ability to retrofit into the existing structure under tight time and budget constraints.
To further expedite the installation process Hydro manufactured a system that consisted of a dry weather flow channel with wet weather overflow weirs incorporating integrated parallel Heliscreen® units. The existing sewer line was blocked with sandbags and pumped downstream so that sewer service was not interrupted. The contractor was then able to install the system from start to finish within a matter of days, minimizing the impact on traffic and the surrounding town.
The installation included a new stainless steel flow channel and four, 20” x 200” screen units – two on either side of a double weir arrangement. The screen system was designed to treat a 1 in 5 year storm event which entailed a flow capacity of 66 MGD.
The Carlisle Street installation combined with the adjacent regulator structure at Atlas works contributes 102 MGD of wet weather flows to the receiving watercourse. Thanks to the Heliscreen® this flow is now free of floatable material greater than 6 mm in size.
Yorkshire Water’s Contracts Manager, Peter Myerscough, commented: “The Heliscreen® is an efficient, versatile and cost-effective unit.”
It is for this reason that the Heliscreen® worldwide installation base is nearly 300 strong.