Impermeable Membrane Shoebox Installation Guide for Attenuation

Impermeable Membrane can be supplied in a shoebox design in two fabricated pieces - the first being for the base and sides and the second for the top with a small overlap down the sides. A non-woven protection fleece is also included for protection of the liner ensuring it will not be pierced by backfill.

1. It is recommended that the complete lined area is covered with a 300g/m² non-woven protector geotextile before backfilling. This should therefore be laid in position before working on the liner.
2. Unroll the geotextile and lay in your excavation.  Leave the excess to one side for completely wrapping around the tank when the installation of the impermeable membrane is complete.
3. The impermeable liner pieces come folded in a concertina fashion on pallets with clear instructions as to where to place, unroll and pull out.
4. Once you have the first piece (it will be clearly marked as the base) - lay it in position and place the crates in position equal distance from the centreline.
5. When all the units have been placed the sides are brought up, folded on the corners (parcel corners) and secured with strips of the double-sided tape.
6. A strip of the double-sided tape is then placed all around the top of the sides and ends approximately 100mm from the top.
7. The second piece of liner is then placed over the top of the units with approximately 250mm hanging down the sides.
8. The corners are, again, folded and the top is firmly secured to the double-sided tape around the complete perimeter.
9. The Attenuation Units are now completely sealed within the ‘shoebox’. To accommodate the installation of the inlet and outflow pipes, small circles of the geomembrane will have to be cut out, adjacent to the relevant positions in the Attenuation Units, and resealed using ‘Top Hats’.
10. The protection fleece can then wrap all the way around the system installation

Installation of Top Hats

To install a top hat stick one side of the double sided tape to the liner around the pipe protruding through the membrane.

Slide the top hat over the pipe and peel the protective cover off the other side of the double sided tape. Press the flange of the top hat securely onto the tape. 

Open the jubilee clip sufficiently to slide the clip over the pipe and top hat to a suitable point - tighten as necessary.