Pond Boss Forums GENERAL QUESTIONS Help Leaky Pond

Hello all,

We have a 1/2 acre pond that was dug in 1980. During construction, two sand pockets were found which were dug out and packed with clay. For 40 years the pond held water pretty well. About 5 years ago, the water level dropped about 2 feet and has never recovered, but it did maintain the lower level.
Last fall we had the pond dredged (suction method) and we lost another 2 feet, Since that time the level has remained at about 4 feet low.
We had an excavator look at the situation recently and were given a $20-$30K price to drain and reline the pond. I'm not sure I'm into spending that kind of cash for re-construction.
We have an unused well on the propery and he suggested that we use it to fill and maintain water level.
If we decide to go with that option, do we just drop a pump into the well and hook it up to a line (1-1/4 line already exists) and let it run? No pressure tank?
How do we determine pump size?
Or can you recommend a resource for me to contact?

Thanks
Steve

IMO your leak is in the upper 4 ft. That is the area that needs to be relined with clay and well compacted not the entire pond basin which may be cheaper than rebuilding the entire pond basin. However to get the job done correctly the pond may need to be drained.

For using the well IMO you first should know how fast the leak drains the pond. Any way to pump from a creek to fill it and measure rate of water loss?

Bill:

With my sand pond, the water level is completely dependent on the ground water level. It was 9' low last December, and I pumped 25 gpm into it 24/7 until we had Spring rains that flooded the timber behind the pond, with water standing there that was about 6" deep. The pond started going over the overflow so I shut off the well. Now my pond is about 3' low and I am pumping water back into it, but it's at best a stop gap thing. When the farmer runs his center pivot that is about 3/4 mile away the pond will drop 1" per day. My pond leaks 18 gpm. at the level that it is now.

smorris might have a leak in the upper 4' of the pond, but it also could be where the sand vein was and the suction crew removed part of the clay packing over the sand vein and he's now seeing ground water level.

If he could dig a hole with an excavator or backhoe to the depth that his pond is in that sand vein, he could see if the water level in the hole mimics the water level in the pond.

I also suspected the ;eak was in the upper portion of the banks. However, the mystery is that for the last 4 years or so, after the pond dropped 2 feet, it maintained that level. After the dredging took another 2 feet, the pond has been consistant at that new level. It seems that if the leak had been in the banks for the last 4 years, the level would have risen back up to the 2 foot mark.

I think I am going to pursue the pumping process. Since I already have a spare well available and most of the piping is in place, all I need is a pump and hookup materials.

So my question at this point is: how do I go about sizing the pump (it's a 4" well)?

As usual sizing the pump depends. Depends on the flow rate abiliy of the well, depends on how fast you want to replace the water, depends of what sizes of pumps are available for a 4" well as I assume the well pump has to fit into a 4" well casing.

I am in agreement with esshup. The dredge suction activity removed the upper layer that was acting as a "bandaid" type fairly thin seal to hold water within the pond basin. Remove the top seal layer and it exposed the underlying seepage area. Now you have four vertical feet of upper leaky pond embankmant instead of 2 original feet. One foot of water depth can expose 2 to 5 linear feet of pond bank depending on the slope.. This exposes more surface area to drain out water.

My dumb opinion is the bigger the pump is the faster you can refill the pond. It comes down to how fat is your wallet for the long term of keeping the pond more full? It could get costly depending on rate of water loss. It is not really an easy answer - IMO.

I would do some more good homework and investigate a proven product called SoilFloc. It is a high-performance pond sealer made from a polymer-based compound specifically designed to stop leaks in ponds and lakes. It’s a two-part, powdered product that works by forming a flexible, water-tight barrier once it bonds with the soil. There are several YouTube videos showing pros and cons of using the product. This brand IMO seems to have a better reputation compared to other brands. All probably dependent on conditions and type of seepage leak.

You are getting good advice above from some very smart pond people.

For the first 40 years, did the pond fill completely after big rains, and even run some water through an overflow pipe? Can you look at the lay of the land and determine if it does fill with surface run off water? (It could still be a groundwater pond that was placed in low ground. However, that type of pond should react a little differently to heavy rains.)

If you can get your pond full after a big rain, put a water gauge ruler (marked PVC pipe, etc.) into the pond and mark the time it takes to reach each lower level. Seeing how long it takes to drop that first foot will probably be your most important number!

If the pond used to reach full pool after heavy rains, but NEVER reaches full pool now, then I expect your leak rate may be too high for you to reasonably afford to keep the pond full using your well. Likewise, if it drops a foot in just a few hours after all of the surface water has run into the pond, then your leak rate may still be too big.

How deep is your water well? And more importantly, how deep is it to the static water level? Also, how far is the well from the knock-down transformer at your house. Your pump sizing requirements may depend more on the electrical requirements rather than the hydraulic requirements - if that makes sense to your level of knowledge.

Finally, if you think your well pumping plan may work, I would call a couple of the water well drillers in your county or wider area. They usually also install and service well pumps. I suspect a crusty old guy could give you a ballpark estimate over the phone to match your expected pond filling usage if you can roughly determine your leak rate.

Good luck on your pond repair. Do you have any good clay in your subsoils near the pond? You might be able to drain the pond just a few extra feet and pack two 6" lifts of clay along the upper 5' of your banks. That should be less than your 20-30K full re-line bid. But you do need to have clay very close for that option.