Slurry lagoon lining in Leicestershire

Dairy and beef in the east of the county

The Vale of Belvoir, the Wreake valley and the rolling uplands east of Leicester carry much of the county's cattle. Many of their slurry stores were dug decades ago as clay-banked lagoons, relying on the Lias clay to hold the contents. Expanding herds, tighter inspection and ageing banks mean a lot of them now need lining or replacing.

Anaerobic digestion adds to the demand. Digestate from AD plants goes back to the land and needs the same kind of sealed, inspected storage.

Relining an earth-banked store

The farm empties the lagoon and scrapes it clean. Next the earthworks team rebuilds any weak or slumped bank and cuts the crest trench, after which we measure the banks and floor against the lining design. It usually costs less than digging a new store and gives the old one a proper liner with a weld record.

For a new lagoon the sequence is the same, starting from freshly formed banks. Either way, protection fleece goes down first so stones in the clay can't puncture the sheet.

Single, double and covered

The build-up depends on what's stored, the site and what the permit asks for. A straightforward farm store may need fleece and a single welded liner. A digestate lagoon close to the Wreake, the Eye Brook or another sensitive watercourse may be double-lined, with a drainage layer carrying any leak to a detection point and a floating cover on top.

• HDPE or LLDPE fused on site, with the day's trial weld logged
• Inlet, pump-out and depth-gauge fittings booted into the liner
• A floating cover where one is drawn
• A handover file of products, weld logs and as-built drawings

Getting rolls into the yard

Liner rolls arrive on a lorry and are heavy. Before we book the delivery we'll ask about the farm track, turning space and whether a telehandler is available, so the materials reach the lagoon edge without holding up the yard.

We also plan around the farm's own calendar. Relining has to happen while the store is empty, which usually means after spring spreading, so it's worth talking to us over the winter, while there's time to book the earthworks, the materials and our crew in the right order.