Making pond liners even bigger: the tricks of the trade for joining and splicing huge pond liners together

John Turner was a flat roofer and has been splicing rubber sheeets and other materials together to waterproof flat roofs all his working life. Now he is passing on the skills that he has acquired at the Firestone Pondliner and Roofing courses. The speed, the neatness and the skill are hard to capture on camera, since they seem so easy and straightforward. But practice is required for all but the lucky few and John's final finished and sealed liner joins and details are an ideal to aim for. The techniques are pretty much fool-proof, so that as long as you remember all the principles and all the steps, you can be sure the liner will remain waterproof at the seams all of its lifetime in service, even if it does look a bit of a mess..

The basic product, the Firestone pond liner is made from EPDM, which is Ethylene propylene-diene terpolymer rubber. It is chemically inert and can cope with movement whilst conforming to any substrate beneath it. It has a natural flexibility and will stretch by 300% and return to shape. The largest sheets that come out of the factory are roughly 15metres by
60metres. So to line a pond more than 13metres by 58metres, you need
to be able to join another liner to it. It gets harder with heat but will not melt, therefore it cannot be fused with itself apart from with an adhesive tape which is a glue on a roll and is effectively like one of those self sealing tyre compounds. This is called Quicskeam Splice Tape.

In order to absolutely guarantee that the Quickseam splice tape will stick, you need to apply Quick Prime Plus otherwise known as Splice Adhesive and is a butyl based contact adhesive.

If the liner is dirty or dusty, it is recommmended that the area to be spliced or glued is cleaned with Splice Wash.

Those are the basic materials for lining a simple but large hole in the ground.

The tools are: a sharp pair of scisssors, a small silicone rubber roller approximately 50mm wide, a Quick Scrubber for spreading the adhesive, a marker effective on rubber (soapstone), a retractable tape measure, a tool for mixing the Quickpime plus/Splice Adhesive.

Splicing two liners together

Mixing the Quickprime plus, then cleaning the blades of the mixer: Just let it spin in the empty box that will hold the Quickprime.	The humble scrubber - the essential tool in applying the Quickprime	The liners need to overlap by 150mm or 6inches.: The splice tape must visibly protrude from the splice by about 1cm. If the liners are dirty, clean them off with Splice Wash and allow to dry.	Fold back the liner by 150mm after marking its position on the overlap.: This is going to allow for a thin strip of Quickseam adhesive to hold things in place whilst the real splicing goes on. It will help in windy or awkward condtions
A thin seam of adhesive is applied to the inside edge of the folded back liner and the outside edge of the liner lying flat	Work along each edge at about half a metre at a time, so that the drying toime for the adhesive is even for both sides.	After 10mins when the adhesive has 'flashed off' and is no longer sticky, fold the liner back over the other: With it lying flat and even and using the edge of the upper liner as your guide, mark a straight line along this edge approximately 15mm away from the edge.	With the liners flat, run a stripe of adhesive from the edge back half a metre. Do this every metre along the liner: This will act as a 'tack' to hold back the liner whilst splicing.
Once the tack strip has 'gone off', fold back the upper liner to reveal the lower liner. The adhesive holds the liner in place	Immerse the scrubbing pad in the primer, let the excess drip off and apply it to the liner edges.....: ..doing the further side first...	cover both edges bit by bit so that they both have roughly the same amount of time to dry or flash off.: Use long backwards and forwards strokes	leave the adhesive to dry until it is no longer stringy when, with a clean finger, you push into it and lift it off.
Apply the Quickseam tape (with the backing paper intact) onto the bottom sheet: aligning the edge of the release paper with the mark on the liner.	Work your way along the liner..	..to the end, smoothing out as you go. Then cut off neatly.: Placing a spare piece of release paper below the tape as you cut it often prevents the scissors from being gummed up by the tape.	Immediately roll the splice with silicone sleeved hand roller along the tape (release tape still in place).
Release the liner from the tacks and fold over the tape	Check there is an even strip of tape visible.: If there is not enough tape going to be exposed, trim it where necessary with a pair of scissors.	Find an end of the paper tape and start to peel from the inside out.: Pull against the weight of the bottom sheet.	Pull the tap off at a 45degree angle and parallel with the flat surface.
Roll the splice with the silicone rubber roller, first across the splice and then....	...along the length.

Splicing Pond liners where there are End laps and 'T' Joints. When to use FormFlash on a joint.

Special considrations are required where you are splicing two liners togther and you come to an end lap or 'T' joint, i.e. where two joints meet.

Where the seam is greater than in length than the tape, the overlap between two adjoining tapes should be at least 25cm. Apply a FormFlash reinforcement (200 x 225mm) over this area.

When several geomembrane panels meet at a common point, only three panels may overlap each other. Apply a FormFlash reinforcement (200 x 200mm) over this joint area.

Also apply a FormFlash reinforcement (200 x 200mm) over the area where a field splice runs from a horizontal area into any slope of the embankment.

Using FormFlash on a joint where one sheet of pond liner overlaps another at a joint

Join the liners with Quickseam splice tape as above. Cut a 200 x 225 patch and always round the edges.: This is the full width of the formflash roll.

Apply Quickprime to the area with the weak spot central.: The area covered liberally more than the size of the patch. Allow this to flash off.

Remove the protective brown paper from the front of the patch and carefully apply the patch to the adhesive coated area

Roll the patch with the backing plastic in place.

Carefully remove the plastic backing and roll the patch into place.

Using FormFlash on a joint where the sheet of pond liner with a joint in it over laps another

A join or seam on top of an adjoining liner means a potential hole on top of the join. The liners should overlap by 150mm: A line is drawn 15mm in from the edge of the liner. On peeling back the liner the small flap of liners that helps form the capillary visible in the picture is cut off at angle. This can be seen in later pictures.	The liner is folded back and Quickprime adhesive is applied to both liners.	Both sides at the same time.	After the adhesive has flashed off, lay the Quickseam splicing tape along the line you have drawn.
Fold the flap of liner back flat over the tape.	Pull out the release paper and smooth the liners together as you proceed.	Roll the seam with the roller.: Note the lack of a capillary along that seam edge.	Apply adhesive to the 'T' joint with the location of the triple layer of liner as central: After this proceed as above by waiting for the adhesive to flash off and applying a 200 x 225 patch with the corners round. Rolling it, removing the plasitic backing and rolling again.

To ensure a positive seal on a join with a seam on top, it is recommended to extend the FormFlash with another patch longways up the seam, half overlapping the first patch.