Pond Boss Forums INTRO New Forum Member Introduction 'Nother New Guy

Afternoon. Been lurking on and off for a bit. Just joined & wanted to introduce myself. Just relocated from NYS to Maysville, NC. Got about a 1 acre excavation the won't hold water. Silty clay mostly but theres a sand layer about a foot above the bottom that allows the water to drain out. Got a quote today for bentonite thats over $40K. Seems a bit pricey buy I dont really know. Will be seeking advice about how to proceed.
Thanks for letting me in....really look forward to getting input and learning from the folks one here

Welcome to Pond Boss, John!!

Welcome John!

I am not a pond building expert, but here is my two cents anyway.

That sand layer has got to go, or has to be sealed away from the pond water!

How thick is the sand layer? If only a foot or two, then I would think your least expensive option would be to excavate and remove it. (Perhaps stockpile the clean sand on shore and later use it for a family swimming beach?)

When churning around in the bottom of your pond site with heavy equipment, you never quite know exactly what is 1" below your disturbed material. Therefore, you usually excavate a little past your total designed depth to ensure you are still in clay, and then pack the disturbed material back on top in a nice compacted sealing blanket. The other option is to heavily scarify (disc) the bottom of the pond. If that is all clay, then you uniformly compact that material back into place.

If the sand layer is very thick, you must seal it away. (Another option would be to sell it if there is a decent market for sand in your area.) If your pond is close to an acceptable depth, and you still have some silty-clay soil in the basin, then you can still seal off the sand - probably for much less that $40,000.

You need to put in some survey stakes in all of the sandy areas. After pounding them in, mark the 6" line and the 12" line. You then need to make a lift of clay that (when compacted) covers to the 6" mark. You then need to do another lift of compacted clay that finishes at the 12" mark. If your pond is deeper than 10', then this sealing blanket probably needs another 6" lift to be sure.

To properly make a compacted lift with silty-clay material, you need to wet the material to the optimum level and use proper compaction equipment. (Just driving over with the dozer treads does NOT create sufficient compaction.)

The bentonite (or other commercial products) can work well when there are some leaks in a sand-silt-clay bottom pond. However, the large pore spaces in a clean, coarse sand in a discrete layer are very difficult to seal.

I hope that gives you some ideas to perform some more evaluations at your pond site and determine which options might be feasible.

Good luck on turning your new hole into a new pond!

I would start over and get rid of the sand layer personally. I know that's not always practical.