Today, after running a bunch of errands to get more parts, I worked on the folds on the bottom of the pond. I know that they will not be visible after the pond is in operation for a while. However, this is a river-flow design, meaning that the water comes in at one end of the kidney-shaped pond and is drawn out at the other end. So it's proper operation depends on a relatively smooth flow along the bottom. I figured that the standing ridges of the folds were going to get in the way of that.
So, reducing the folds. I got some 3" seam tape, made I assume for joining pieces of EPDM together. This material comes in a roll 3" wide by 25' long, and costs the princely sum of $60! I have never seen anything as sticky and rubbery as this stuff: once you touch it, you own it --- there's no getting it off your hands, and the piece that you touched is trash by the time you get disengaged. It comes with release paper between the wraps of the roll.
The 3" width was about twice what I needed so I slit the roll down the middle for a little less than a full wrap of the roll. The only sane way to apply this stuff is to then partially pull the release tape from one half of that width, and roll the whole roll along the fold so that the revealed half bonds to the liner.
Keep doing this until you have enough of the seam tape in place. You can see that I used short pieces butted up one to the next. When you run out towards the narrow end of the dart (fold), you have to stop because there won't be enough of the folded liner to be folded onto the seam tape.
Then fold the fold onto the seam tape, and roll with a wallpaper seam roller.
Covering this glued fold with the cover tape is much simpler: pull off some of the release tape and roll the revealed tape onto the seam; then pull the release paper and roll a bit at a time until you have the seam covered.
It makes a pretty clean installation.
Next was to cut in the bottom drain (BD). I pulled back the liner to get at the drain body that was already attached to the drain pipe that will lead to a pump. I cleaned out the holes in the drain body where the holddown screws will go --- they had gotten full of sand. But a 5/32" drill bit fit perfectly in those holes: by turning the drill bit by hand, all the sand was carried up and out of those screw holes.
The I pulled the liner back into position and cut the liner where the center drain hole of the BD is. The next step is to find out where those screw holes are under the liner! but you can feel the holes through the liner pretty easily, and stick a nail through the liner and into a couple of the holes so that you can get an idea as to how the top part of the BD will line up. Then I put some plumber's acrylic caulk between the drain body and the liner, and between the liner and the top part of the BD, and ran the screws in. You don;t need to pre-drill for the screws; they just go easily right through the liner.
Then hopping into the pump pit, I installed a 3" double-union valve on the BD drain line. Wow, those valves are big and awkward to deal with. But I got it installed. That was important because it's supposed to rain tonight, which would start to fill the pond, and I didn't want to lose all that water.
Maybe TPRs cut in tomorrow. PROGRESS!