thanks for info trent,
i have no regrets about not digging a core. adding a liner now will cost me no more than digging a core when the dam was built. the valley the pond is in has numerous natural springs & the soil is quite rocky. so even w/ a core, i may still have had leaks.
as for the liner, no one has quoted me anything or suggested any thickness. 45 mil epdn seems to be the most commonly stocked size, & it cost the same as 35 mil pvc (~$.35/sq ft).
my plan now is to drain the pond, smooth the sidewalls out a bit, install underlayment & liner & cover the edges of the liner w/ soil. still undecided on cover the rest of the liner w/ soil.
