SVC-01 · Attenuation Tanks
Attenuation tank installation
Geocellular attenuation tanks, supplied and installed.
An attenuation tank holds stormwater below ground and releases it at a controlled rate, keeping your development compliant and the drainage network downstream safe. We supply and install complete crate systems — fleece, membrane, welding, connections and testing — for residential, commercial and industrial sites across the UK.
- System
- Geocellular crate tank
- Void ratio
- 95–97%
- Membrane
- 0.6–1mm, typically 0.75mm LLDPE
- Protection
- 300gsm geotextile fleece
Attenuation Tanks in short
An attenuation tank is a below-ground store, built from geocellular crates, that holds stormwater and releases it to the drainage network at a controlled rate. Aquatech Civils supplies and installs these tanks, or installs only, with protective fleece, an impermeable membrane heat-welded at every joint, a recorded test weld, and inlet, outlet and flow-control connections. Every job comes with full QA and handover documentation.
The system
What's in the package
One team from supply to handover documentation.
- Crates, fleece and membrane supplied to the drainage design
- Heat welding with calibrated equipment — no taped joints
- Test weld and QA record on every job
- Inlet, outlet and flow-control connections
- Full QA and handover documentation
How it goes in
Installation process
- 01
PH-01
Formation check
Your groundworker digs and forms the excavation. We check it before we start — level, debris-free, with sand or gravel blinding where the ground demands it — and tell you straight if it isn't ready.
- 02
PH-02
Fleece & membrane
300gsm protective fleece then an impermeable membrane, cut and dressed to the tank geometry. Every joint is heat-welded — never taped.
- 03
PH-03
Crate assembly
Geocellular crates lock together at a 95–97% void ratio, built layer by layer to the designed volume and loading class.
- 04
PH-04
Connections & controls
Inlets, outlets and flow controls are formed and sealed to the drainage design — seven connections on one recent tank.
- 05
PH-05
Test & handover
A test weld is carried out and recorded, the system is inspected, and you receive the QA and handover documentation for building control.
Specification
Specification
- System
- Geocellular crate tank
- Void ratio
- 95–97%
- Membrane
- 0.6–1mm, typically 0.75mm LLDPE
- Protection
- 300gsm geotextile fleece
- Joints
- Heat-welded, test weld recorded
- Loading
- Landscaped to highway-rated
- Scope
- Supply & install, or install only
Turnkey
One team from supply to handover documentation.
Welded, never taped
Every membrane joint heat-welded into a continuous barrier, with a recorded test weld on every job.
Documented to sign-off
QA and handover records as standard, covering what building control and adopting authorities ask for.
UK-wide
Midlands based and working the length of the country, with 25+ years in the ground.
Case studies
Attenuation Tanks projects
Supply only
Supply only
The same materials we install, at trade prices with UK delivery — for groundworkers fitting their own.
SUP-02Direct from manufacturerLiners
0.6mm HDPE membrane — Juta Junifold
Impermeable HDPE membrane by the roll
- Material
- HDPE
- Thickness
- 0.6mm
- Rolls
- 2.5m × 50m · 5.1m × 100m
from£600.75
ex VAT per roll · £720.90 inc
SUP-10Direct from manufacturerLiners
1mm HDPE membrane — Juta Junifold
Heavier-gauge HDPE membrane by the roll
- Material
- HDPE
- Thickness
- 1mm
- Roll
- 2.5m × 30m · 75m²
£631.80
ex VAT per roll · £758.16 inc
SUP-08Direct from manufacturerLiners
0.75mm LLDPE impermeable membrane
Flexible LLDPE in 2.9m and 5.8m × 50m rolls
- Material
- LLDPE
- Thickness
- 0.75mm
- Rolls
- 2.9m × 50m · 5.8m × 50m
from£522.00
ex VAT per roll · £626.40 inc
Asked on site
Frequently asked questions
If your site discharges to a network with limited capacity, planning conditions will usually set a maximum discharge rate. An attenuation tank stores the difference during a storm and releases it slowly. Your drainage engineer sets the volume; we build it.
Most tanks are installed in days, not weeks. As a reference point, we completed a 970m³ tank with seven connections in five days, including on-site reconfiguration around an unmarked water main.
Tape relies on adhesive holding underground, under pressure, for decades. A heat weld fuses the membrane into a single piece of material, and every job carries a recorded test weld before backfill.
Yes — install-only is a normal way to work with us. We'll flag anything about the supplied materials that affects the warranty or weld count before we start.
Weld test records, as-built details and a QA sign-off pack — what building control, the adopting authority and your client's warranty provider expect to see.
Adjacent systems
Related services
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