Tonsley Basin

DESCRIPTION OF PROJECT

T&J Constructions successfully completed the construction of three biofiltration basins, including full earthworks, basin wall formation, and all associated drainage layers. Each basin was excavated to the required design levels and shaped to form stable batters and structural walls in accordance with the IFC drawings. Works included trimming, formation of the basin footprints, establishment of design benches, and creating uniform and stable side walls to ensure longterm performance and integration with the adjoining Linear Reserve corridor.

Following earthworks, we installed the complete drainage layer systems for all basins, including the placement of gravel drainage layers, transition sands and, where applicable, filter media and geotextile separation as required in typical biofiltration basin specifications. Underdrain pipework, inlets, outlets and connection points were installed to facilitate proper hydraulic function and controlled discharge back into the reserve drainage network. Despite the challenging winter conditions, our team successfully managed water flows and maintained the integrity of the drainage layers throughout construction, ensuring each basin met quality, stability and design requirements.

PROJECT CHALLENGES

• Carrying out earthworks, drainage installation, and biofiltration basin construction during winter presents significant technical and environmental challenges. Throughout the winter delivery period, we were required to temporarily control water flows to maintain safety, protect the works, and ensure compliance with environmental obligations.
• Completing the project in winter significantly impacted construction due to wet ground, continuous water ingress, and the need for temporary water flow diversions. Despite these challenges, the works were successfully managed through proactive water control, resequencing, and ongoing environmental and safety measures.

KEY CONSTRUCTION PROCESSES