After reading many of the threads on this message board, I took on a small pond project in my backyard. I made these videos while lining the pond with sodium bentonite. I will make and upload the third and final video to youtube soon. After I finished the lining the pond we had a tropical depression and it rained for three days fully filling the pond. A personal thanks to all here that contribute to this message board to help others.

Houston home Inspector lines pond with sodium bentonite Part I

Houston Home Inspector lines small pond with sodium bentonite Part II

How long has the pond been full? Is it maintaining it's level? How many pounds per square foot? Sorry if all this is answered on the videos, I am viewing from work, uh, I mean I'm not on my home computer and have no sound.
Greg
ps. I am in the process of doing the same right now, so am very nervous and curious. I don't want to undergo all the work and expense to not get a seal.

The pond has been full for over a month now and it's holding fine. I have a one inch water line to it which a sprinkler zone dedicated to the pond. I have it add water automatically for an hour three times a week. That keeps up with evaporation and some seepage around the top edge. I think I'm a little light on the bentonite at the top edge but I wanted to make sure I used most of the bentonite that I had from the bottom of the pond on up, figuring it's a lot easier to till in more bentonite at the top edge if I ever had to come back and do that. I probably won't be adding any more any time soon as I figure running the sprinkler zone is fine and if I had grass there I'd probably be running the zone more than that this time of year anyway.

If I was to do it again I suppose I'd consider getting more bentonite and tilling way up to the very top rim of the pond and maybe put a top covering of soil over the mixed blanket (that seemed like a lot of trouble at the time I was doing it however so i decided against it). I'm satisfied with the results so far. I used two pounds of bentonite per square foot but I had a soil with fairly high plasticity. Your results may vary. I think some folks that have done this more than me might advise you get the most bentonite you can afford to get. The more, the better.

I am glad you are having good results.
I am doing overkill, I hope, I have been recommended to use 6 tons, so for peace of mind, I am using almost 9 tons. I plan to put 6 to 12 inches of soil cover over the mixed blanket to protect from livestock if they happen to get into the pond and swimmers. I will also go a bit heavier in the depths, but plan to till in all the way up.

Hey pointman,
Where did you but the sodium bentonite from? Texas Sodium? I hear there is a difference in bentonite?

I used the Wyoming sodium bentonite, a Halliburton product from Baroid Industries. I called Baroid and they gave me the names and numbers of several suppliers so I called around for pricing. They make several different sizes of the granular bentonite for drilling and other purposes. Casing seal and Benseal are what I used. The Casing seal was cheaper than the Benseal but i ended up with both due to what they had in stock. Benseal is marketed as a pond sealer, Casing seal is used for drilling mud.

I priced sodium bentonite from west Texas (Comanche)but by the time I paid for shipping to Houston there would be relatively no savings difference so I went with the Wyoming bentonite which I believed to be a superior product.

Another supplier near Columbus had a product he sells as a pond sealer and it's calcium bentonite which doesn't swell but it's very cheap. Although the owner of the company seemed very credible and convincing, I just could'nt find other references speaking to calcium bentonite as a reliable pond sealer.

What does anyone here think of calcium bentonite as a pond sealer?

Some folks wanted to see a part III so here it is Sealing a small pond with Sodium Bentonite Part III

I'm including this video of a tool that I use to read elevations. It is definitely useful for marking pond edges and contours. It's easier to use than a level and transit and it's easily operated by one man.

One man operated elevation measuring tool

I have watched your youtube vids because I'm thinking about lining my pond bottom with bentonite? What was the size of that pond and how many bags of bentonite were used? Thanks for any info.

wow! I really don't remember it's been too long. The pond is small, about 1/8 acre. 2 pounds per square foot so one bag covered 25 SF. Seems like I had 8 pallets full so I'm gonna guess that I remember it was about 20,000lbs. See Gmoores comment above. Mixed blanket is the way to go.

Yeah I was going to do the mix blanket. I was told I need 387 of the 50lb bags. So basically 19,000 lbs. Found a dealer locally but dont know the price. My pond is 65x75 5' deep at the middle. Its a dished bottom. I'm praying that will be the fix i need