Pond Boss Forums INTRO Questions & Observations test pits dug...water table???

Update--test pits dug and showed "glacial till hardpan" at about 4-5'. Contractor said looks good, they just need to carve the pond, crush up some till, and repack it with a sheepsfoot.

Mason jar test looks good for 50-60% clay (if I am reading it correctly). Also, poked some holes in a coke can and compacted a couple of inches as hard as I could. That was Monday and it has only lost about 1/8" of water as of Thursday morning.

About an hour after they left, I went down to look at the pits and noticed that water had began to seep into all 4 pits. The pits were only dug to about 5-6', showing a relatively shallow water table. They now have about 8-10" of water.

Is this good news or bad? My thinking is that if water can get in, water can just as easily get out. Granted this is raw soil, that hasn't been mixed and compacted, but it still worries me.

Will a good compacted layer isolate this water table? Is this a good thing or a bad thing?

Thanks,

Joe

Anybody?? I know there are some pond folks out there with some insight this.

Joe,is this the normal depth of water table in your area? If so is it constant at this level year around? If it is constant then it really want matter if your soil holds water or not. With your discription the pool level would be around 3 to 31/2 ft from ground level. I would build an excavated pond if this be the case. I'm certainly not familar with your area and conditons and your question is to hard to answer without knowing the facts. Are there other ponds in your area? If so are they excavated or runoff ponds? If your contractor is familar with your area he may be the best person to consult.

hey joe, i know a little (that was a great skynard song), but its hard to give you exact answers for the reasons rocky states. that said, water tables usually fluctuate on a seasonal basis. in my neck of the woods, they can vary over 10 vertical feet from spring to winter. if you built the pond to hold water at levels higher than the water table, and did not seal off the water table, the pond would seep and lose its water until it re-equilibrated with the level of the water table. the rate of loss would be completely dependent upon the shallow subsurface geology, but it sounds pretty high based on the rapid re-charge into the test pits.

as rocky said, sounds like the choices are

A) to dig out the pond so that the high water mark corresponds to the current water table level(hoping yer water table doesnt vary much seasonally), or

(B) construct a high sided dam and line the bottom with compacted clay soils above yer current water table level.

Not sure if this counts for anything but I recently drained one of my small ponds. Within a day or so water seeps up and fills it partially to about 6 inches. When I fill this pond completely, seepage is not a problem. In fact, the very slow rate it does go down (maybe an inch a month if that) is probably due to evaporation.

Hey Joe...
do ya remember this thread ?