Pond Boss Forums POND CONSTRUCTION Soil questions New pond-seepage

I have a 3/4 acre pond dug last year with a dozer.
Contractor said the soil was as good as it gets..i checked the soil and you could ball it up and it would stay together..so I put structure in the bottom, drilled a well, and started pumping 20 gallons a minute...we had some good rain before I started pumping and the bottom seemed to hold the water well..and came up several feet and stayed...the level continued to come up till I had about 8 feet in the deepest part..and then it did not come up any further..with recent rains it came up 2 foot and now has gone back down a foot in a week period even though im still pumping water..I did the soil test where you pack it down and put water on it and it leaked out overnight..question is how long should I give this new pond time to "settle" or "soak in" ? Water is not up to side of dam yet and no leaks on the backside of the dam..
I have read through the other posts and am a little confused about this issue.. I did not have the soil packed ...he ran over it with his dozer..will the water pressure help compact it over time? Has anyone had success with applying bentonite to the surface of a pond if they have just a small seepage problem?

Hello Jeff,

My experience with applying bentonite through the water was not effective at all! My experience was with seepage throught the dam. I would give it a little more time and see what happens.

just rattling some ideas around here for discussion purposes.

sounds to me like you got one of about three potential things going on (all minor variations of each other):

1) if it is all good clay.......because bottom or sides werent compacted, the water level gets to a certain height, and the hydraulic pressure becomes great enough to force water through yer pond sides or bottom but is slow enough to stay in ground downgradient of pond (hence you see no leakage).

2) maybe yer whole substrate really isnt clay. maybe you got a silt soil that the contractor didnt really identify. then same problem as above only a faster leak.

3) maybe you have a coarse grained layer (sand/gravel) only a couple feet below yer clay, and because of no compaction, the water found a pathway, gets in the coarse soil, migrates downgradient from pond but stays underground (hence you see no leaks).

if the leak can be determined as related to these types of problems, my truthful recommendation would be to drain, verify soil types, and compact, compact, compact.

anybody else?

Jeff,

If I'm understanding you, the clay is holding water fine. Only when the water level came up to the topsoil did you start losing water. If that's the case, I'm betting your pond will hold water once the topsoil is soaked and settles down. It may take a while, so be patient.

I agree with Bobad. Give it another season to mature before spending more money on bentonite.

Hey Bobad I went by your place yesterday. What are you doing with all of those piles of clay? Your lake looks good. You need to come see mine. [email protected]

i surely hope you two are right. problem is, as i've seen in not only my pond (before i fixed it) but in a couple other ponds, is they hold fine til a certain level, then when it goes above that level, it cant hold and drops real fast back to that certain level. in these cases its either a leaking layer in the sides, or the volume increase and subsequent weight of water is able to hydraulically push itself out through bottom.

i wouldnt waste any money on bentonite either, and maybe i'd wait a year to see if its just needing to saturate the surroundings, but if it keeps acting that way, its leaking, and will need a better fix than just dumping bentonite in (MO). jeffh, the water pressure itself will not help compact the substrate, but it can help move fine grain materials into cracks and help seal a pond in the right situation.

Dave, Jeff,

To illustrate how topsoil can suck water, my main pond always held water just fine. I recently dug a small, shallow minnow pond right next to my main pond. The little pond is so shallow that the bottom is all topsoil. It took weeks for the water level to stabilize a bit, and still drops at a higher rate than my main pond.

Thanks for your input..I am in the process of sending some soil samples to the state lab to check for clay content etc..I appreciate your advice..I have decided to wait a year or so and see what happens..I thought about trying to compact it on the sides but there really is no way to safely get a rig in there..the dam is too steep..I also considered adding bentonite around the sides but that would not stop the leakage completely...so I guess just wait it out..thanks again for the input...