I am new to the forum and have very much enjoyed reading all of the information here. I haven’t been able to find what I’m looking for so I’ll go ahead and ask.

I purchased a property that has 4 acre woods with a .5 acre pit on the south end of it. The pit has to be over 100 years old and will completely fill with water in wet years and dry up in a drought. When full it holds about 4’ of water. I would like to clear the trees and brush away from the edges, with the exception of one neat old sycamore tree, and dig it down to about 10’ of average depth. It is surrounded by farm ground that we farm so I would control the nutrient load on the cropping acres and also plant a grass water way where it fills to reduce sediment entering the pond.

We have a quote for the project which I think it reasonable. My question is for $5-10k would it be worth it in the long run to add .2-.4 of an acre to the get the pond size closer to 1 acre? We would like to use the pond for fishing and swimming, probably would stick to LMB and BG, maybe some cats and RES. Trying to figure out from a maintenance and fish population standpoint what would be the easiest to maintain in the long run. Thanks!

I would focus on the plan to seal the pond as the primary goal. I personally think that the cost of expansion is well worth it as long as the pond seals properly. However, a larger dry hole is not a good thing.

Use a sheepsfoot roller, and lay down clay in 6 to 8 inch layers, and compact it as it is laid down. You need at least two feet of well compacted clay on the bottom to seal it. You will want to make sure it seals. A leaking pond is no fun. I know from experience. We didn't use a roller, only a dozer on the first pond. It's been seven years, and no seal yet. We compacted the second pond bottom with a wheeled backhoe with a bucket full of dirt. It finally sealed, in about a year. A roller would have been much better.

Boilergeek,

I think we need a bit more information.

Can you determine the use of the old pit? Was it a rock quarry, a sand pit, etc.?

When it fills with water in the wet years, is the water surface runoff or is it subsurface ground water? If you don't know, is there a berm of spoils around the pit that blocks surface runoff, or is the pit at the end of a waterway across your farmland such that it appears to be designed to catch that runoff?

I ask all of those questions, because your required work on that pit to turn it into a pond varies greatly depending on how the water currently enters AND exits the pit.

The old pit was more than likely used to build up the base for an old abandoned railroad that runs along the property. I don't believe it was built to be a pond, however I do know that it used to hold water better than it does now. It has a clay base but it needs some trees and stumps removed and a core trench put in. There is a waterway that feeds into it that catches about 8-10 acres worth of surface runoff. The water level raised about 18" after a 4" rain event this summer so I think it has plenty of watershed to go bigger if I want. My main concern at this point is trying to figure out if going bigger is worth the extra expense or not.

That all sounds like very positive news to me!

If it was just a borrow pit, then they probably didn't create any "extra" problems for you.

8-10 acres of watershed is probably a little too much for a 1-acre pond. (Which is a good problem to have!) Therefore, you should be able to support your pond expansion plan (if all of the OTHER factors look favorable). You might even consider the option during the planning phase to have the ability to divert water around your pond. A big rain on freshly tilled ground is going to try to wash sediment into your pond.

If you are deepening the pond and it is already down to a clay subsoil, then try to doing it during your driest time. Wet clay is no fun to work on.

If it used to hold water better, but there are trees and stumps on the "dam" area, then they are probably the culprits. The path created by a big root after it rots away can leak out a lot of water.

Good luck on your new pond project!

Rod, here we need roughly 10 acres of watershed for a 1 ac pond.

Thanks for the correction.

(I was using the USDA Handbook #590 - which shows the average for Indiana to be around 4 acres of watershed to 1 acre-ft of pond water. Though using acre-ft as the water need parameter doesn't really make sense since evaporative losses are only based on surface acres. A 10-foot deep pond would need 40 acres of watershed by that math. I find that handbook to otherwise be a pretty accurate guide.)

It sounds like if he can expand to 0.7-0.9 acres that would be good except for the drought years, and if he stays at 0.5 acres that would also be a good size to mostly manage his expected large rain events.

<snip> [quote]The path created by a big root after it rots away can leak out a lot of water.[quote]


I've always wondered about that. After roots rot, wouldn't the paths collapse and be filled with soil or clay, stopping the leak eventually? Maybe after several years?

In unconsolidated material (like loose sand) the particles typically collapse and fill any voids. (Although that weak fill would probably not stop a flow of water.)

In compacted, cohesive material (like clay) the particles can have enough structural strength to support the load of the overburden - and keep a root tunnel open.

I was digging in a clay bank yesterday that was covered with elms and catalpas. Sometimes I would get roots caught in the excavator teeth, and they just pulled out of the bank. They were leaving perfect circles when I was pulling on a root from the larger end.

Probably driving heavy equipment over the dam repeatedly might collapse the tunnels?

I doubt it.

It is difficult to compact dry clay materials. Especially if your tree root hole is 6' deep.

Like Fishinrod said, very small chance of it, if it was left alone for a really long time it might finally shut off completely, but with water in the pond, not likely, if water ever starts down that path, it will create its own artery in one rain event, remember water will follow nearly every small imperfection in the ground in a spot as small as a grass layer that was not cleaned off and roughed up properly to create an adhesion with your fill material, and it takes a very small root to guide the water down that path, it will create a bigger hole by itself in very little time.

I've heard that "dynamic compaction" will work on poorly compacted dams, but it is probably very expensive.
Here is a website that explains it.

https://www.keller.com/expertise/techniques/dynamic-compaction


I guess using something like "Soilfloc" might be an option for poorly compacted clays.

Care to wager what a crane that can lift 30 tons costs to get to the job site and set up, then what is the hourly rate is on something like that? Might be cheaper to dig the dirt out and compact it properly with a sheepsfoot roller as it's replaced.

.[/quote]
Care to wager what a crane that can lift 30 tons costs to get to the job site and set up, then what is the hourly rate is on something like that? Might be cheaper to dig the dirt out and compact it properly with a sheepsfoot roller as it's replaced.[/quote]

Probably cost more than redoing the dam with a dozer and roller. But, at least the crane would avoid draining the pond.