Pond lining in Leicestershire

Why clay ground still gets a liner

It's tempting to assume a pond dug in Leicestershire clay will hold water by itself. Sometimes it does, for a while. But boulder clay is full of stones and sandy lenses, the mudstone is fissured, and a dry summer opens cracks in the banks that can drain a pond down to the cracks. A liner takes the guesswork out.

Some of the county isn't clay at all. The Soar and Wreake valleys carry gravel that drains freely, and in Charnwood Forest the old volcanic rock is hard and angular. Those formations need a thicker underlay to stop the ground working against the sheet.

Ponds we line across the county

Tell us what the pond is for, what it will hold and how it's filled. Those three answers decide the specification. Fishing lakes need firm banks for anglers' pegs, reservoirs need a ramp for the pump, and newt ponds want shallow margins, and each one changes how the edge is finished.

• Coarse fishing lakes and match waters
• Irrigation reservoirs on arable land in the east and south
• Great crested newt and mitigation ponds on housing sites around Leicester
• Wetland and wildlife ponds in the National Forest around Ashby and Moira
• Golf course water features and estate lakes

Choosing the sheet

HDPE is the toughest choice for big reservoirs exposed to sun and wear. LLDPE and PP are more flexible and sit well on the irregular banks of a fishing lake. EPDM comes in large single panels and suits smaller ornamental ponds. GCL gives wildlife ponds a natural clay bed, as long as it's covered and the water suits it.

Thickness follows the job, typically 1mm to 2mm. A shallow wildlife pond under soil cover can take a lighter sheet than a reservoir bank that will see sun, wave action and the odd quad bike.

The work on site

Excavation isn't ours: your groundworker or farm contractor shapes and trims the hole. We look the formation over, roll out the underlay, place the liner and fuse each seam with wedge or extrusion welders. Pipework and outlets get sealed boots, the edge is buried in a perimeter anchor trench, and we log a trial weld before we pack up.

Fishing lakes and reservoirs in the county are often big enough to need several days. We work in sections so each day's welding is finished and covered by the anchor trench before we leave.