Pond Liner options
Pond Liner options
(OP)
I am designing a pocket pond here in NY, and I need a pond liner to sustain the permanent pool. NYSDEC Stormwater Manual lists acceptable options: (a) 6-12" of clay soil (b) 30 mil polyliner (c) bentonite (d) chemical additives.
I'm looking for advice on performance/cost benefits for the different options and which in your experience is the best. Thanks.
I'm looking for advice on performance/cost benefits for the different options and which in your experience is the best. Thanks.





RE: Pond Liner options
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RE: Pond Liner options
RE: Pond Liner options
30-mil poly liner will hold water just fine, but it needs to be protected from damage. If not covered with soil it will A) be ugly and B) eventually be full of holes. Cost per SF varies, but for a small job it will be significantly higher (mobilization costs, etc).
You could amend the existing soils with bentonite, and use that as a relatively impervious barrier. Depending on your soil types, 4% to 8% by weight ought to do the trick. If retaining a permanent pool is the only issue and a small amount of seepage is OK (no environmental issues) then this may be a cost-effective way to go. If I remember correctly, granular Bentonite currently sells for about $350/ton. Figure your pond liner volume (6" thick is probably fine), then how much bentonite to add. It has to be added and properly mixed in to the native soils, then compacted for it to be effective. It is a pretty low-tech process than any good earthwork contractor can do.
RE: Pond Liner options
Good comments from DMcGrath. Our experiences with bentonite/soil mix are essentially the same.
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RE: Pond Liner options
Dik
RE: Pond Liner options
If you can run some storm drains to it and pick up irrigation water from lawns you may be able to sustain your pool, especially because it seems you get a lot of rain in New York.