Radlett – Landfill Processing for Rail Infrastructure

Project Overview

Provectus was appointed by VolkerFitzpatrick to remove and process a historic municipal landfill directly in the path of a major new rail chord. The site lay adjacent to a SPZ1 aquifer, requiring careful leachate and groundwater management. Our goal was to clear the landfill, recover as much reusable soil as possible, and enable the rail project to progress without delay.

​

The project’s innovative and sustainable approach earned shortlisting for a Ground Engineering Sustainability Award.

​

Key Challenges

• Historic mixed municipal waste containing hazardous fractions such as asbestos, POPs, PFAS, and hydrocarbons.

• Sensitive hydrogeology due to proximity to an SPZ1 aquifer.

• Requirement for rapid delivery to align with rail construction milestones.

• Need to minimise waste to landfill and reduce environmental impact.

​

Our Approach

Excavation & Waste Removal

• Targeted excavation to design depths, managing varying waste composition.

• Incremental sampling and classification of materials in real-time.

• Safe handling of hazardous materials in line with regulatory controls.

On-Site Processing & Reuse

• Deployed an Environment Agency-permitted mobile treatment plant.

• Mechanical separation using trommels, screening decks, and conveyor systems with debris netting.

• Moisture control through windrow drying and ~2% lime dosing for cohesive soils.

• Recovered soils meeting geotechnical and environmental criteria placed back on site as Class 1a fill.

​

​

​

​

​

​

​

​

​

​

​

 

 

 

Water Treatment

• Installed a dedicated plant, including reverse osmosis, to treat high-ammonia leachate and hydrocarbon-impacted water.

​

​

​

​

​

​​

​

​

​

​

​

​

​

​

​

​Backfill & Compaction

• 36,000 m³ of recovered soils placed and compacted to highways specifications, following detailed inspection and testing plans (ITPs).​​​​​​​​

​

Results & Volumes

Excavated landfill material - Mixed municipal waste, variable composition

Recovery rate - 50–66% - Dependent on waste composition

Reusable soils placed on site - 36,000 m³ - Class 1a fill

Lime addition for moisture control~2% Improved screening and compaction performance

​

Outcome

Through careful planning, regulatory engagement, and innovative processing, Provectus delivered a high recovery rate and significantly reduced off-site disposal volumes. The project met all environmental and safety requirements, protected the adjacent aquifer, and kept the £6 million early works package on schedule, paving the way for the rail infrastructure works to proceed.