Elite Precast Concrete

Retainer-Rock® Supports £10m Upgrade at Dronfield Wastewater Treatment Works

Installation of Elite Precast Retainer-Rock walling at Dronfield WwTW

As part of Yorkshire Water’s ongoing commitment to improving river water quality across the region, the company has invested £10 million in a major upgrade of Dronfield Wastewater Treatment Works in Derbyshire.

The improvements, delivered by principal contractor Tilbury Douglas, will enable Yorkshire Water to significantly reduce the amount of phosphorus discharged from the treatment works, helping to improve water quality in the nearby River Drone and supporting wider environmental objectives.

CPC Civils were responsible for delivering the main civil engineering package, which included site enabling works, installation of precast concrete structures, pipeline connections, drainage infrastructure and construction of a new backwash pump station.

The scheme also required multiple retaining wall structures. To meet the project’s technical, programme and aesthetic requirements, Elite Precast Concrete’s Retainer-Rock^® walling system was selected, providing a durable, low-maintenance earth retention solution with an attractive natural stone appearance.

Why Retainer-Rock^® Was Chosen

Retainer-Rock^® is an engineered, interlocking precast concrete retaining wall system designed to combine structural performance with a natural stone aesthetic. The dry-laid modular blocks can be installed quickly and efficiently while offering the flexibility to create both straight and curved wall alignments.

The system provides the mass and interlocking characteristics required for gravity retaining walls and can also be configured with a tie-rod jointing system, where higher wall heights or site constraints demand enhanced stability. This versatility made it particularly well suited to the Dronfield scheme, where installation speed, restricted working areas and long-term durability were key considerations.

Fast Installation

The use of dry-laid modular blocks enabled rapid construction with reduced on-site labour requirements compared with traditional cast in-situ retaining structures. This helped CPC Civils maintain programme efficiency and meet critical commissioning deadlines.

Long-Term Performance

Manufactured from high-quality precast concrete, Retainer-Rock® delivers a robust and durable retaining solution with minimal maintenance requirements and low whole-life costs. An important consideration for operational wastewater treatment facilities where future access can be limited.

Attractive Finish

The textured stone-effect face of the Retainer-Rock^® units complemented the surrounding environment adjacent to the River Drone, providing a neat, visually appealing finish that met stakeholder and community expectations.

Supporting Sustainability Objectives

The use of precast concrete units reduced on-site waste and minimised installation activities, helping to lower overall site impacts and support Yorkshire Water’s wider carbon reduction objectives when compared with more plant-intensive construction alternatives.

Successful Delivery

The civil engineering package, including the Retainer-Rock^® retaining walls and numerous precast concrete structures, were delivered safely, on time and within budget.

The upgraded treatment works were successfully commissioned in December 2024, meeting Yorkshire Water’s regulatory deadline and delivering important environmental benefits for the River Drone catchment.

The successful completion of the project also strengthened CPC Civils’ relationship with the principal contractor, resulting in further opportunities as part of Yorkshire Water’s AMP8 investment programme.

For More Information, contact us at https://www.eliteprecast.co.uk/