Spillway Repair
Stonbury was contracted to deliver repairs to a spillway in Lancashire after the existing gabion baskets supporting the structure had degraded.
Stonbury replaced the perished gabion baskets at the end of the spillway with a more durable concrete wall to secure the assets long-term safety and functionality.
Prior to works commencing, an ecology survey was conducted, and overgrown trees were removed prior to bird nesting season to avoid risk of delays. An eco-welfare cabin was utilised to lower the programme’s carbon emissions.
After installing a ramp and scaffolding access into the upper and lower sections of the spillway, Stonbury installed a Portadam system with a central relief pipe to release flows from the spillway onto the other side of the works. Coir silt traps were placed on the lower side to catch debris and prevent it entering the watercourse.
The team dismantled the degraded gabion baskets as well as some additional baskets to create room to cast the new support structure, while stockpiling the stone for reuse.
The area in front of the spillway was excavated and levelled with new stone before a concrete base and kicker was laid. Steel reinforcements were affixed on the concrete face and shuttering and formwork was installed in which to cast the new concrete wall and wingwalls.
Once the concrete was cured and the shuttering and formwork had been removed, the team instated new gabion baskets flush with the exiting baskets and the newly cast wall and filled them with the saved stone.
The new concrete wall has restored the structural integrity and safety of the asset and has provided improved ongoing erosion protection to the spillway.
