Pond lining in Birmingham

Where lined water sits in a city

City ponds fall into a few groups. Parks and nature reserves have ornamental lakes and wildlife pools, some of which have been leaking for years. Schools and community gardens want small teaching ponds for dipping. Estates going up on Birmingham's outer fringe often come with a balancing pond that is meant to keep a permanent level of water.

On the mudstone in the east of the city a pond can look as if it will hold on its own, but clay shrinks and cracks in a dry summer and the level drops. On the sandstone to the west an unlined pond simply drains. A welded liner takes the guesswork out on both sides of the city.

Picking the right liner

We recommend from the pond in front of us, not from a price list. Size, shape, what lies beneath it and what the water is for all count.

• EPDM for small ornamental and wildlife ponds with curves and shelves
• LLDPE or PP where an awkward shape needs flexible, weldable panels
• HDPE for large balancing ponds and reservoirs that need toughness
• GCL where a natural clay bed suits a confined, gently sloped basin

Relining leaking park and garden ponds

Much of the city's pond work is repair. Old concrete basins crack, butyl sheets perish along the waterline and taped joints let go. We inspect the existing lining, find out why the pond is losing water, and fit a new welded system over a fresh protection layer, with pipes and outlets sealed in rather than patched.

Access in parks and back gardens is often through a gate or along a path, so we plan panel sizes and the welding sequence around what can actually be carried to the hole.

Underlay, edges and records

Birmingham formations often carry brick, glass and old foundations from made ground. Your groundworker trims the basin; we lay a geotextile underlay over it so nothing sharp can work up into the liner over the years.

Round the rim, the liner is turned down into its anchor trench so frost, wind and footfall can't drag it in. On public sites we work to the landscape designer's edge detail, whether that is a planted margin, stone edging or a shallow beach for wildlife. Before the first seam on each pond, a trial weld is run, tested and written into the record.

Fitting the work around the seasons

Welding wants dry, mild weather, and a park lake may hold wildlife that an ecologist wants left alone at certain times of year. We agree the window with the site team early, so draining, trimming and lining follow on without the basin sitting empty for weeks.