"Cybe R. Wizard" Cybe_R_Wizard@WizardsTower wrote in message news:20040121084925.79fad3b5.Cybe_R_Wizard@Wizard sTower...
[...]
In your position I think I'd get an experimental piece of heavy tarp or
a discarded pool liner to use. Dig, pile, shape, trim pre-liner as you
like it. After it's just like you want, tear it all back out (leave the
hole). You now have a template to use on your 'real' liner and have
done all the nasty work without having to risk harm to the 'real' thing.
It will also help to gauge the amount of runoff you actually get. I've
been/very/ surprised at how much water runs down my little valley.

Cybe R. Wizard

The trick might be getting it dug properly and getting a liner in it
before it fills. I almost hope it does leak so that I will have more
time.