Car park lining in the New Forest

Where the work is

Inside the Park boundary, parking tends to be small, informal and surfaced to suit the landscape, and a fully lined permeable pavement is an occasional job rather than a regular one. The bigger schemes sit in the towns and on the Waterside: supermarket and retail car parks, employment sites, care homes, schools and parking courts on housing schemes.

On those sites the drainage engineer often can't let water soak away. Valley clay won't take it, winter groundwater can rise into the sub-base, and some brownfield land shouldn't have runoff driven through it. A lined pavement keeps the stored water separate from the ground and lets it go at a controlled rate.

Lining the formation

Once the groundworker has cut the dig, our first job is an inspection: is it level, are sharp stones picked out, does it drain towards each outlet? If not, you hear it from us before any fleece is unrolled. Protection fleece covers the base and sides, the membrane panels are spread over it, and each joint is fused with heat where it lies, with a test weld written up.

Pipes leaving the sub-base, from the outlet chambers to any overflow, are each sealed to the liner. Round the perimeter the sheet is turned up to the drawn level, then a top layer of fleece guards it against the stone that follows.

Forest town sites bring their own constraints: mature trees with protected roots along the boundary, neighbours close by, and lanes that struggle with a large delivery. We agree the drop point and a laydown area for the rolls with you before the visit, and keep the working area inside the site.

Programme and handover

The lining is one step in the groundworks, between the dig and the sub-base. We fit our visit to that gap so the membrane is covered soon after it is welded, and hand over with the weld records for building control. Where the design adds geocellular crates beneath some of the bays, we build those as well.

• Formation check
• Fleece both sides of the liner
• Welded membrane, no tape
• Sealed outlets and penetrations
• Weld records at handover