We are bidding the site work for a new gas and acetylene plant. The retention pond will be completely dug into the ground with a 30,000 yd cut and zero fill. It will be 16' deep and will continuously hold 10' of water. There is a concrete box with a pump. The pump will feed the buildings fire suppression system in case of a fire. There is a pressure line and return line that has not be designed yet. The soils we will be digging in, is sand and gravel and may hit shale with solid rock. The engineers require a liner consisting of a minimum 35mil or clay with benotnite. What I am worried about is digging 16' deep in sand and gravel and underground spring popping the liner. We thought about digging a curtain drain, but there is no place to take a drain since we are completely dug into the ground. Does anybody have any experience with this type of system ?? I am thinking about checking into Firestones rubber pond liners or talking to the engineer about using shotcrete. Oh yeah, the company wants a 20 yr guarantee that it will hold water. ointhead
that benotnite is like puttin down 3 ft of clay. I have work with that stuff you just got to make sure that you cover every inch that you put down in a day. put down the liner till 12 and start to cover what you put down. that way you are not their till 10 spreading topsoil.. cause when it gets wet it turns to jello an you cant spread topsoil to well on it. as far a draining the pond when you are digging it. you got to dug a sump hole that you can pump in.
If you do not run into immediate water welling up from the cut, then you should be able to make your excavation, perform the necessary under-liner work, install the liner, and fill the pond. The weight of the water in the pond above the liner will hold it down no problem. If you have excess ground water during excavation, then you will need to find some way to divert it and pump it out of the works while you complete the preparations for installing the liner. The synthetic liner is far superior to a concrete or gunite liner. For one thing, it's very flexible and will adjust to soil subsidence where the cement pond may settle and crack, thus causing a leak. The flexible liners also last a long, long time without much maintenance. I helped build several very large ponds at Kennecott Copper near Magna, Utah where we used liners that were actually constructed in place from rolls of material that were laid out in place on the slopes, than vulcanized in the pit. Took rather large crews of laborers, an IT28 Cat equipped with forks, A 65KW gen set, and the vulcanizer machine. I really didn't think folks were using Clay/Bentonite much anymore as pond liners with the availability of synthetic liners. The last time I was involved with the stuff, other than in the oil patch, was in cut-off trenches at Lake DeSmet in Wyoming in the mid-seventies. We had to use it to keep water from running out of the north, south, and east side of the enlarged lake thorough the natural scoria material. We made a slurry composed partly of Bentonite and poured it into 35' deep trenches, then covered them over with natural fill.