Client: Yorkshire Water (in collaboration with Seymour Civil Engineering)
Location: Sherburn, North Cowton, Kirk Hammerton
Project Summary:
Originating from a strong existing relationship with Seymour Civil Engineering and Yorkshire Water, Lynas Engineers was tasked with delivering structural and drainage design services at Sherburn, North Cowton and Kirk Hammerton sewage treatment works sites. These projects were part of Yorkshire Water’s initiative to increase stormwater storage capacity across multiple locations, following on from the initial stormwater storage expansion reports Lynas Engineers produced for 13 Yorkshire Water sites.
In addition to this primary objective, each design ensured minimal disruption to ongoing site operations; achieved first time approval at every Yorkshire Water Key Stage meeting; and were completed in accordance with the UIMP6 compliance date of 31st March 2024.
At each site, the new designs were integrated within current infrastructure following 3D analysis of existing site information. These projects highlight Lynas Engineers’ ability to provide practical, innovative solutions while meeting the technical and operational requirements of a large-scale infrastructure upgrade.
Sherburn
- Objective: Increase stormwater capacity by 16m³.
- Solution: Due to limited space, this design involved a cast insitu concrete U-shaped tank installed against the outer existing tank wall. This solution allowed the new tank to be constructed offline whilst the existing tank remained operational. Through collaboration with structural engineers at JMEC, an underpinning sequence for the existing tank wall was developed to allow our new tank design to connect at foundation level.
A 150mm thickness internal reinforced concrete wall was cast against the outside of existing masonry tank wall to provide a watertight finish within the new tank. We included a 650mm height handrail around the edge of the new tank and lowered the surrounding ground level to ensure the design provided 1.1m edge protection in accordance with Yorkshire Water design guidance.
- Challenge: To keep the existing tank operational during construction, we designed the new tank to be constructed offline. Due to the existing tank foundation being lower than that of our new tank, an underpinning sequence for the existing tank wall was developed to allow our new tank design to connect at foundation level, through collaboration with structural engineers at JMEC.
- Outcome: The work was completed on time, without disruption to services. In subcontracting to JMEC, a York-based firm, we utilised a local supply chain, drawing on their structural expertise to ensure an efficient design while supporting local businesses.
North Cowton
- Objective: Increase stormwater capacity by 24m³
- Solution: We designed a rectangular reinforced insitu concrete tank which connected to the existing tank at 90-degrees through a new 1.2m diameter manhole to avoid existing constraints and provide a buildable solution within the available space on site.
- Outcome: Delivered on time, the design met all objectives and ran smoothly from start to finish.
Kirk Hammerton
- Objective: Increase stormwater capacity by 54m³
- Solution: Similar in layout to the new stormwater storage tank design at North Cowton, but larger in scale, this design required a manhole at approx. 90 degrees to connect to the existing stormwater tank. Through collaboration with FP McCann, we developed a rectangular precast concrete tank and handrail design and by liaising with Eliquo Hydrok included a self-cleaning flushing bell in our design. This innovative system, autonomously removes sediment, reducing future maintenance needs and costs.
- Outcome: The project was completed successfully, with the flushing bell ensuring long-term savings on maintenance costs.
