Civil Engineering
- ClientMorgan Sindall
- ValueTBC
- DurationJuly 2025 - October 2025
"This project demonstrates our ability to deliver complex civil engineering schemes whilst working within highly regulated environments. The scheme involved managing work to protect a critical site asset that required a collaborative working relationship with our client, Morgan Sindall"
Gareth Collins - Operations Manager
The brief
As part of our ongoing relationship with Morgan Sindall, we have recently removed and replaced degraded gabion mattresses and boulders on a reprofiled riverbed that provide protection to a foul water drainage crossing and nearby fish easement.
Our scope of work on this scheme included:
- Removal of existing damaged gabion mattresses.
- Excavation/filling with rock (Rip-Rap) to reinstate the level foundation for new gabions.
- Excavation/filling of the fish easement channel to match design levels.
- Installation of Butyl liner within the fish pass and north of the foul drain pipe.
- Installation of boulders (3t-4t) and rockfill in the new fish easement channel.
- Installation of 16 300mm deep new gabion mattress units.
- Installation of scour protection bounders (3t-4t) and rockfill at the head and toe of the gabion mattresses.
Key quantities:
- Gabion Stone: 140 t
- Riverbed Gravels: t
- Rip-Rap: 80 t
Challenges & successes
The River Calder channel passes through the Sellafield nuclear licensed site and is flanked by high security fences. Access for all plant and materials for this project was to be done via the nuclear site and over the high security fence using a 250t mobile crane, an operation which required meticulous planning and received high levels of scrutiny.
The River Calder is a salmon river and therefore works within the watercourse needed to be carried out between 15th June and 30th September due to fish spawning restrictions. This restriction, coupled with regular flooding of the work area, resulted in heavy time pressures and variations to the work scope.
Successful installation of 60no. dumpy bags of fill to create a dam and largely dry working area in each half of the river channel at a time.
Outputs & Benefits
Long-term Protection: This project ensures long-term protection (10-year design life) of the North foul drainage crossing.
Enhance Fish Populations: This project provides a channel for fish by-passing the gabions and improves habitat populations.
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