Rainwater Underground Storage - SuDS

• Surface water drainage system.
• Pipework and manholes.
• 21m x 4m x 1.2m SuDS underground crate storage system.
• Petrol interceptor.
• Hydrobrake chamber and other manholes.
• Pumped discharge to watercourse.
• Highway crossing.
• Complex buried services system.

Sweeting Bros (Land Drainage) Ltd were contracted in the role of Principal Contractor under CDM 2015 to provide an extensive surface water drainage system including petrol interceptor and underground storage capacity works.

The underground crate system storage tank was designed to hold the capacity of 1 in 100 year storm with a 30% uplift to accommodate climate change and took rainfall from the associated area having first passed through the petrol interceptor.

Excavating the area, protection layers were placed first, prior to the encapsulating liner in the base. The crate system was then installed and fully encapsulated.

The surface water drainage comprised a gravity drained system followed by pumping to discharge. Discharge was controlled via a hydrobrake manhole and pipework was installed along the site perimeter, crossing a highway with outfall into a nearby watercourse.

Traffic management for highway works was necessary together with accommodating a comprehensive network of buried services.

Health & Safety

All works were carried out compliantly under CDM 2015 protocols requiring Construction Phase Plans together with comprehensive assessment of all risks and method statements to minimise risks for all work elements.

Working with Water

Working in or around water poses hazards for employees arising from the natural environment. The presence of vermin and exposure to leptospirosis twinned with the possibility of drowning, all add to the normal risks involving accidents concerning machinery and moving parts. Works taking place in live watercourses also pose problems arising from adverse weather and increased rainfall. It was necessary to monitor and adjust programmes to accommodate and minimise risks. Pumping out of accumulating / rising ground water is often necessary to ensure safe working conditions.

Cooperation

As with any large project where multiple stakeholders are involved, co-operation is key factor in success. Sweeting Bros Ltd are adept at managing multi-agency stakeholders.

A railway line was within 200m of the proposed works resulting in Network Rail participating in the planning/execution of the works.

Traffic Management

A fully Chapter 8 compliant traffic management programme was implemented and adapted to differing layouts throughout the project to accommodate working in the highway, weight and height restrictions on ancillary lanes and roads.

Residential access to adjacent properties also had to be accommodated for the duration of the works.

Buried Services

Extensive surveys were necessary to understand any risks prior to undertaking any excavating. These involved large gas, water and electricity mains which needed to be addressed and managed.