ATC-0673 · Attenuation
673m³ attenuation tank for a new Lidl store
A 33.6m × 12m × 1.67m Rigofill SD attenuation tank for the new Lidl store at Corby. At roughly 673m³ it's a big single tank by any standard.
- Location
- Corby
- Region
- Northamptonshire
- Sector
- Retail
- Completed
- 2026
Attenuation · Corby
673m³
- Ref
- ATC-0673
- Region
- Northamptonshire
- Sector
- Retail
- Year
- 2026
What we did
NW300 geotextile laid across the formation, a 0.75mm LLDPE membrane welded panel to panel, the Rigofill SD crates built up to the full 1.67m depth, then the membrane and fleece wrapped over the top and the inlet and outlet connections sealed into the wrap.
The tricky bits
Footprint. A 400m² base takes a lot of membrane, so the panels were laid out and welded in sequence to keep every seam testable, and the welds were pressure-tested on site.
What we delivered
A fully wrapped 673m³ tank ready for backfill, with its welds tested and recorded.
The tank
The tank is 33.6m long, 12m wide and 1.67m deep. Rigofill SD crates lock together into a single block, built layer by layer on the welded base until they reach the designed level.
The groundworks team dug and formed the excavation. We checked the formation before the geotextile went down.
The membrane
0.75mm LLDPE is the membrane we fit on most tanks. It is flexible enough to dress tight to the corners of the crate block and it welds cleanly panel to panel. The NW300 geotextile sits on both faces: under the membrane on the formation, and over it once the wrap is closed, so neither the ground beneath nor the backfill above can puncture it.
Every joint was heat-welded. None were taped.
Sign-off
The installation was signed off on site in May 2026. The backfill is the groundworks team's; we hand over before it, with the weld test records and QA documentation building control and the warranty provider ask for.
- Volume
- 673 m³ (33.6 × 12 × 1.67m)
- System
- Rigofill SD crates
- Membrane
- 0.75mm LLDPE, welded
- Geotextile
- NW300
On site · Corby
On site
Two adoptable storage tanks, 276m³ in total
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