MWH Treatment (MWHT) were selected to design and build the Minworth Thermal Hydrolysis Plant (THP), Severn Trent Water’s largest sewage treatment works, serving a population of 1.75 million. The owner’s first THP, the plant utilized digital engineering and off-site construction techniques to increase the amount of renewable energy generated, saving 50,000 work hours on the project. Approximately 70% of the equipment was manufactured and assembled off-site (DfMA) to improve project efficiency and quality and shorten the program. Laser-scanning of assets, 3D models and fly-throughs, and 4D scheduling enhanced the quality and efficiency of the design and construction process from concept through commissioning.

The £125m upgrade scheme was successfully delivered by the MWHT North Midland Alliance from a site-based co-located office with Severn Trent, Pick Everard and a key supplier. In addition, the work included several capital maintenance schemes across the whole of the site including an extensive program of replacement, refurbishment and improvements to existing assets identified by operation and maintenance risk assessments. A key strategic intention of the project has been to increase the gas production performance of the 16 digesters and enhance the output of the existing site renewable power generating station has exceeded expectations.

As part of its submission to regulatory authorities in the UK, the Owner made a commitment to cut its total carbon footprint by 10% and convert 25% of all their biosolids to an enhanced status product. The Minworth THP helps accomplish this goal, delivering a third of Severn Trent’s 10% reduction target.