We are digging out a once started lake. Today we dug a test hole and at about 18 feet deep water started to bubble out and the next few buckets was coarse gray sand with small pieces of coal mixed in it. The hole started to fill up slowly with water. Everything previous up until this point is excellent clay.
18 feet was roughly the depth we planned to dig the pond. The big question is do we dig down to the sand and water level or should we stay up at least 2 feet from the sand and water and call it good enough?
We drained some excess surface water down into the test hole and filled the entire hole up to see how much it will drain down in a few days. If it doesnt drain down much would that be a good enough test to see if it will hold water?

EDIT: Here is a link to a video showing the pond.
http://www.youtube.com/watch?v=B0Qd7UGa_WE

Howdy, bummer.

You hit sand and coal. Bummer.

Stay above the sand layer. Aim for at least 2' of good clay between your pond water and the sand. If you hit the sand somewhere while digging, pack it off with 2 feet of compacted clay (hard to do when it is wet, I know from experience).

The sand that oozes water out today will suck you pond water in tomorrow. Holding water at less than 18 feet is better than an 18 foot hole that won't hold 18 feet of water when ground water levels have dropped, taking your pond with them.

Hi Bummer,welcome to the forum.Im not an expert,just one of the lowly members lurking around here.But I think Theo is absolutely correct.A spring is great until the water table drops and sucks your pond dry,breaking your heart and killing all your fish.

Hi Bummer,

Welcome! Great pond, great toys, great tour! Thanks for the film clip, and best of luck with your project!

Thanks everyone for the comments! We will cap off the sand areas with clay as you guys recommend. I will also report back here with any news and once the lake is done I will try to get some more video. Thanks

Smart. Picking up the grease gun before starting to work. Dang, I'm jealous.

bummer Welcome to the show

General Theo is right do not take the chance 15 feet is deep enough.

Theo was promoted to General?

Great, I guess now we have to salute him and whatnot.

At ease.

Hi all
Update: We did not get to work on the lake last year, but it was a good test to see if it would hold water and in 3 different test holes all held water. We also discover that beneath the sand is clay. There is a 2 foot thick layer of sand.
Here are some videos of the lake progress and some haul truck action.
Wish it would stop raining for a day.

would like to ask, im in the dreaming phase of a pond. while i am reading these answers, it makes me wonder , to dig past the sand. and end up with a spring. if he does that. cant a person just hook up a pump or windmill to raise the water level when it drops. where i live, the water table fluctuates, but doesnt dry up, im within a half mile from a large river, and i want to dig as deep as i can. i know i will hit sand and water before 18 feet. what do the experts say about digging past the sand and using a windmill for a pump?

also, im considering putting in a artesian , but not sure of the local laws concerning it. i heard you have to cap off if you hit artesian spring. wondering about the feesibility of that.

Once you hit sand and water you have gone too deep. Trying to fill it from a well is like running water into a bathtub with drain open.

thanks dave, makes sense.