"RichToyBox" wrote in message
. ..
"Bill Stock" wrote in message
...
I ask because I took out the old PVC liner today and I discovered that it
no loner touched the bottom of the pond when empty. It was in decent shape
after six years although perhaps a little brittle.

I was going to let the new liner settle (with water) about 24 hours
before cutting the hole for the bottom drain, but if the old liner is
still settling after six years!

The other bad news is that the weight of the water has turned the clay
into one large brick bowl, even the Mattock has a hard time breaking it
up. I was hoping that all the moisture around the pond would make the
clay soft, but that is not the case.

I don't think that the bottom was still settling, the vinyl shrank when
allowed to dry. My daughter pumped her swimming pool dry and allowed it
to be dry for a few days to do some major cleaning after not using it one
year. The sides shrunk enough that the bottom was pulled up the sides
some. She had to replace the liner due to shrinkage.

When you install the bottom drain, concrete around it to prevent it from
twisting or shifting. Pull the liner into roughly the final position,
making sure that there is liner enough to go around. The hole for the
bottom drain can be cut into the liner and the bolts attached as the first
thing done. Start filling with water and pull the wrinkles out, working
outward from the bottom drain. Wait until the water level is up to the
skimmer opening before cutting for the skimmer. The weight of the water
will be pulling down on the liner from the top as it conforms to the exact
shape of the pond and could pull away from the skimmer.
--
RichToyBox
http://www.geocities.com/richtoybox/pondintro.html
Zone 7A/B Virginia

Thanks, the plan is to put a patio slab under the drain and then cement the
drain on top of it. The skimmer will attach with a bulkhead opposite the
waterfall.

How much below the pond bottom should the drain opening sit? 3/4"?

I more or less have the shape dug now (taking a break from the chiseling),
but I really won't know what I want until I see it. I still have to get the
depth I want (probably another 2') in order to break into the drain line. I
will soak the clay with water overnight so I can scoop out the bottom.

Then comes the hard part, digging the remaining plumbing channels.