ATC-CHE · Attenuation
Attenuation tank, pressure-tested to record
An attenuation tank at Chesterfield where every weld was pressure-tested and logged — the QA discipline that turns a lined tank into a documented, warranty-ready record.
- Location
- Chesterfield
- Region
- East Midlands
- Sector
- Commercial
- Completed
- 2026
Attenuation · Chesterfield
10 welds
- Ref
- ATC-CHE
- Region
- East Midlands
- Sector
- Commercial
- Year
- 2026
What we did
Supply and install of the crate system with a 1mm membrane, welded panel to panel. Each weld was numbered, pressure-tested and recorded — the photo shows Weld 10 under test, dated on the membrane itself.
The tricky bits
Nothing gets covered up until it passes. Testing and logging every seam takes discipline on a live site, but it's what building control and the warranty provider expect — and what we hand over as standard.
What we delivered
A tank with a complete weld-test record: every joint proven before backfill, documented and signed off.
The site
The tank serves a new wood recycling plant on the outskirts of Chesterfield. At 970m³ it is just short of 1,000m³, and it sits under what will become a car park, so it had to carry regular HGV traffic. It was built from Brett Martin StormCrate55 heavy-duty crates, 15.5kg each, with the crate numbers calculated by the manufacturer's technical team from the architect's drawings.
A reserve for firefighting
The tank does two jobs. It attenuates stormwater from the site, and it holds a reserve of water as part of the plant's fire risk plan. The outlets were set 400mm above the tank invert, so a minimum volume of water stays in the tank at all times, ready if there is a fire. The tank has seven 300mm connections in all, wrapped in a 1mm LLDPE membrane over 300gsm protective fleece.
Working around a water main
During the install we found a buried water main that hadn't been flagged to the site. The tank was reconfigured on site and built in two stages around it, keeping the full attenuation volume.
The membrane came in 3m rolls, not the 6m rolls we normally use, which meant a great deal more welding. Every one of those welds was pressure-tested, and the internal corners were extrusion welded. The whole tank was installed in five days and handed over on programme in April 2026.
- System
- Geocellular crates
- Membrane
- 1mm, welded
- QA
- Every weld tested & logged
- Scope
- Supply & install
On site · Chesterfield
On site
Attenuation tank lining
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