Williamthorpe Sewage Treatment Works

Overview

Mason Clark Associates (MCA) has worked with contractors, Stonbury on numerous projects.

For the Williamthorpe Sewage Treatment Works (STW) project we were appointed to provide design options to improve the storage capacity of stormwater.

This work is part of a larger effort by Yorkshire Water to cut down on how often stormwater overflows from sewage treatment sites across the region during periods of heavy rainfall.

The project improves local water quality and boosts the natural environment, encouraging more wildlife to thrive in the nearby lakes.

Challenges and Solutions

Williamthorpe STW is located near the Williamthorpe Nature Reserve, making effective stormwater management essential to protect nearby natural habitats.

The site operates as part of a combined sewer system, which handles both wastewater and surface water thus making it particularly sensitive to heavy rainfall events.

Space was a key constraint on this site, the new tank had to be installed at a precise level below the previous tank to maintain flow, but still above the outfall into the nature reserve to ensure the system operated effectively within the existing hydraulic gradient.

Two options were designed and presented for a feasibility test. Option 1 was the design of an earth-banked lagoon and option 2 was for an open-topped concrete tank. The feasibility process undertaken by Stonbury concluded that the tank would be the most suitable option.

MCA's Contribution

Mason Clark Associates provided civil & structural engineering services for this project, delivering key design elements and technical input to enable construction planning.

Key contributions included:

• Development of two feasibility options.

• Design of a watertight reinforced concrete storage tank, including specification of water-retaining concrete and jointing details.

• Design of flow diversion chambers, penstocks, pipework and weirs.

• Design of a watertight reinforced concrete storage tank, including specification of concrete mix to suit durability requirements, ground contaminants and the Contractors on-site pouring programme in regard to enhanced curing times.

• Technical presentation of the scheme to the end client and asset owner Yorkshire Water with Stonbury during the KM3 and KM7 milestone meetings.

• Provision of clear, buildable drawings to support delivery on site.

Our experience with similar schemes allowed us to deliver a practical and efficient design that met the client’s needs with minimal complexity.

Results

The project progressed efficiently, with clear design outputs tailored to the client’s requirements.

The proposed design offers a practical and cost-effective solution for increasing stormwater storage capacity, while maintaining flexibility for future site development.

The successfully completed tank provides an additional 100m3 of stormwater storage.

The use of a proven design approach has helped streamline the process and reduce design risk.