Attenuation tank installation in the West Midlands

Why so many West Midlands sites need attenuation

Much of the region sits on Mercia Mudstone and other clays that take water slowly, so infiltration is often ruled out and surface water has to leave the site through a sewer or watercourse. Across Birmingham and the Black Country that usually means a network with little spare capacity, and a planning condition that caps how fast your site can discharge into it.

An attenuation tank holds the difference. During a storm it fills, and a flow control lets the water out at the permitted rate. Your drainage engineer sets the volume, the discharge rate and the loading class. Our job is to build the tank exactly as drawn, so it holds the volume it was designed to hold.

What an attenuation tank installer does on your site

We don't dig and we don't backfill. Your groundworker excavates and forms the hole; we build the tank inside it and hand it back closed and ready for cover. Keeping our scope to the tank is what lets us arrive with the right crew and kit and get off site quickly.

• Formation checked before anything goes down: level, free of debris, blinded where the ground needs it. If it isn't ready, we tell you.
• 300gsm protective fleece, then an impermeable membrane, typically 0.75mm LLDPE, cut and dressed to the tank.
• Every membrane joint heat-welded with calibrated equipment. Never taped.
• Crates assembled course by course to the design's volume and load rating.
• Inlets, outlets and flow-control connections formed and sealed as the drainage design shows.
• A test weld made and logged, then the wrap closed over the top.

Supply and install, or install only

We install whichever crate system the drainage design specifies, from landscaped-area units to highway-rated tanks under car parks and service yards. Crates, fleece and membrane can come from us, specified to the design, or we can fit materials you already hold. Many clients take install-only, and before work begins we point out anything in their materials that bears on the warranty or how many welds the job needs.

A recent tank in Birmingham

At Swanhurst School in Birmingham we installed a 115m³ attenuation tank, 32m long, 3m wide and 1.2m deep. On a fenced school compound with a fixed programme, the liner was prefabricated to the tank's size to cut down welding on site. The crates were built inside it, the wrap was closed over the top, and two 300mm fittings were sealed through it before sign-off.

Our yard is in Tamworth, a short run down the M42 and M6 to most of the conurbation, so West Midlands tanks are often on our programme the same week you call.