Cost for impervious storm detention liner?

[oregonpe]

Has anybody had any experience with impervious liners for underground chamber type storm detention systems such as Stormtech? First, my reading of the Oregon UIC requirements seem to preclude any infiltration potential even from an open outlet detention system. This is for a fairly large 65,000 cf storage system serving a 10 acre industrial parking lot.

Stormtech recommends a 30 mill PVC liner with 8 oz non-woven reinforcement fabric under and over the liner. Does anybody have an idea what 15,000 square feet of this stuff would cost? Seems like it might be cheaper to go with a hard piped system.

Gary Van Dyke

 

[psmart]

Are the regulations prohibiting infiltration (in which case you would need a sealed system), or are they just not giving credit for infiltration flows from the underground storage?

In the later case, a sealed system would not be required. You just omit any infiltration in your sizing and modeling calculations, thereby providing more conservative (oversized) storage.

If the infiltration itself is prohibited, there are many concrete and CMP storage options you could consider.


Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[Mark1961]

There are a number of suppliers of this product. It is relatively easy to goggle. Transportation costs are expensive since this stuff is heavy. Also, most manufactures may not be able to provide one-piece liners for 30 mil and will need to have a field seam and overlap. We used one not to long ago and it was not that expensive. AS for the chambers, the storage capacity and the low profile make it very attractive, as is the ease of installation. Sorry I could not give you a specific cost since there are too many variables. Try

http://www.geocheminc.com/pvcfront.htm

Mark

 

[oregonpe]

Thanks Mark1961 for the web link. That looks like a good site.

Peter, infiltration is strongly discouraged here. I fall to see the problem with a fully drained pond in class c soils but Oregon DEQ has everybody scared about ground water liability even for swales. For years we were perking everything and thinking we were being environmental. Now you need special permission and only if there are no other alternatives.

I'll try to do a cost analysis, but i really like the stormtech type system and HydroCAD makes it a breeze to model.

Gary Van Dyke

 

[psmart]

Gary, It's amazing how radically the infiltration regulations vary from state to state. Most of the country is starting to mandate infiltration, while other areas prohibit it entirely...

Anyway, if you're going with a closed system, you may want to consider round or arch-pipe, and avoid the cost of a separate waterproof membrane and stone backfill. There's a free chamber update for HydroCAD 8.5 that adds many common round and arch-pipe shapes to the chamber library. For details see

http://www.hydrocad.net/chambers.htm

Peter Smart
HydroCAD Software

http://www.hydrocad.net