I was going to add this to my original thread but thought of starting a new one here related to the dam. I've lost 7" of water in 24 days and rain seasoning coming to an end, we are now in our 3rd summer without a full pond.

Last night, I drilled 6 test holes with a spud bar in the backside of my dam a couple feet below the current water line as best as I could tell. It has become clear the dam is not holding and was improperly built. The new "pond side" core trench helped and we feel that the bottom is sealed. We think there is rock (bedrock/sandstone) beneath the dam was not removed and certain the dam was not compacted in proper lifts.

We are now thinking of building a new dam, within/behind the first dam. Water is hard enough to come by so I want to do everything we can to keep what we have without pumping out.

Does anyone have experience in this type of repair?

I would talk to user, teehjaeh57, about Soilfloc first. He provides his time free to Pond Boss members. Hopefully he sees this and posts.

Yeah, I spoke to TJ a bunch, he knows the story. I just confirmed the problem yesterday and think it's bigger than just a couple of leech spots.

I can't remember your dimensions.

How big is the pond? Length and height of the dam?

Pumping out the water and repairing the existing dam might be much cheaper than building a second dam. However, you do lose one year on your pond.

Building the second dam adjacent to the first dam might be a little dangerous with water seeping though the first dam. While you are working on the core trench you would have saturated, unstable soils above you. Trench collapses kill lots of construction workers.

If you are building a second dam, is there enough room to move farther down your waterway and make it a second pond?

If the elevations work out, then the leak in your first pond would only drain the water level down to the water level of the second pond. As long as your second dam is well sealed, then your first pond will also hold water.

Just spitballin' ideas to get your creative juices going since I expect you are chomping at the bit to get your pond fixed!

Good luck!

Ryan - .3" daily vertical loss and likely .10-.15" due to evaporative loss this Spring, so you may be looking at .2" daily loss due to dam seepage. I would seriously consider whether it's worth further investment of rehab or polymer chasing such a minor leak. Anything 1/3" or less daily loss we consider in the pond construction business as a successful project provided you're living in an area with decent annual precipitation [25" or greater]. It's your $, and I'll always help however I can, but if it were me I'd count my blessings and adopt a holding pattern.

However, your scenario is unique that you can't pop a well for supplemental irrigation and your watershed is limited, so if you elect to do pursue addressing the poor dam construction/seepage I suggest comparing the cost of core trench work vs. treating the dam face with a polymer application. I'd wager 3-4 units would address your dam seepage successfully at a fraction of the cost/time of rehab. I know you've already spoken to Drew Hay out of PA [one of the best pond builders on the planet], and he could likely provide a rough estimate on dam rehab project.

I'm glad your main basin is holding well following rehab and polymer - we just never anticipated your dam also being an issue. Reach out whenever you need me.

My contractor was down there today and said all of my test holes were full of water. They average 2ft deep. The dirt spanning at least 50% of the width (115 ft) appears to be saturated half way down outside face.

I'm honestly worried about the dam sliding apart at this point. Even thought I don't see any sign of running water.

New to forum. How do I ask a question or start a new thread please? Thanks

PP24, see Thread Options in blue above. Click on it and New Thread will be there with other options.

BTW, welcome to Pond Boss.

In the case of the dam sliding apart, then I'd say yes to building a new dam behind the existing one but make double durn sure that it is done correct this time. Then breach the old dam and once the water level stabilizes, remove as much of the old dam as you can, which probably will entail an excavator and a dump truck. .

Well, my #2 crew has come and gone. They spent last week clearing trees and brush from about a 1/2 acre to access more dirt then dug out a new core down the entire 230' center of the existing dam. The top 18-24" was dry dirt then we found gray wet mud (not sloppy) down10 feet before we hit dry dirt again. He lifted and compacted with better material from our new borrow pit and used a sheep's foot and the weight of 100k rock truck to get the tightest compaction possible.

It appears the first contractor built the dam from muddy/ garbage/ pond bottom material and covered his tracks with a foot or two of better material. I've reseeded with 250lbs of grass seed, some food plot forage and finished off with some fertilizer. This is the 3rd iteration of planting grass. The last step is straw, which I am leaving to the crew to come back a blow into place before the end of the week.

There was no significant sign of leaking other than the dam material was a lot wetter than should have been. It was junk material and not compacted at all. We've lost about 4" of water since last Tuesday until today, but hope it's just from the saturation into dry material.

I've also will be applying 2 units of soil floc to the inside face of the dam (below the waterline) before the end of the weekend.

Fingers crossed....

Sounds like an excellent build THIS time! I am glad the repairs were made safely.

Too bad you had to get a crap job the first time around.

It sounds like you will be fine from now on out. Great news!

Well, does anybody want to take a guess as to the status of this pond project?

Don't tell us it is still leaking?

I like happy Pond Boss stories and pictures!

Unfortunately yes. I've lost about a 12-13" of water in the last 6 weeks. We haven't had much in the way of rain so I suspect some evaporation.

The pond was in a constant state of filling from August 21' until about March 22'. Any rainfall we had rose the water level. Of course, the surface area was much smaller then. Even with a wet spring and summer, would come up a 1-3" and fall back down. The only real way I think we'll know is when the ground freezes again. Lack of run-off has always been an issue especially since half of my runoff acreage is covered by trees.

I figure we still need 1-1.3 million gallons to achieve full pool. If the pond fluctuates a foot or so over the summer from full pool, I wouldn't mind that all.

12-13" loss in 6 weeks sounds bad, but that is only 0.29" per day.

When re-filling a pond after construction, some portion of your water went to fully saturating the pore spaces in your bottom and side material AND rehydrating the clay minerals.

I hope you get it full next spring, and it holds "almost" like a bathtub!

.29” daily without factoring atmospheric influences (evaporation) and you’re likely under .20” daily of leak loss. In my industry we don’t even consider that a leak. IIRC Your pond was constructed too large for the watershed to support and there’s no opportunity for supplemental irrigation (well) aside from creek pumping. Going from 2-3” daily loss to .25” is in my opinion money very well invested and nothing short of miraculous. You reduced your loss by 95% or better - what were your expectations? Your results sure blew my predictions out of the water.

The pond has never achieved full pool since it was dry last August after the 2nd major rebuild/application. It has fluctuated 8-12 inches all summer and has been low 4 1/2 to 5 feet since March of 2022. This last and more significant construction effort did nothing to slow down the seep/ leak.

The silver lining I suppose is that we have a much wider dam that will do a better job holding back the last 4-5 feet of fill, assuming it fills over winter. It will also be a lot easier to the backside of the dam since was graded less steep with more material.

I was down at the property couple of weeks ago. There has been little to no rain since August and we're down 15.5" over a 60-day period. It's been a long time since it's been this dry. My neighbors pond is down about half that much but is 2 acres in size. I really hope we have an exceptionally wet winter.

We are dry as well, and the water level in our ponds is also low. Hope this is not a weather trend!

I. Down about 3 ft. I need a storm.

Dave you and me both!

We finally got 1.65" at our farm!

I haven't been out yet, but I suspect very little made it to my ponds. Hopefully, some made it to our creek.

I really needed it to water our winter wheat crop. It was planted without enough soil moisture to ensure germination. Hopefully, the rain was gentle enough to not erode off our mostly bare soil cover.

We finally got some rain ourselves over the weekend. 2" rainfall netted 4" of water in the pond. Boy was the ground dry.

We have had some small increases in the water level in the last 10 days with the weather staying wet and cold. Not enough for big run-off events, but the surrounding soils are getting saturated again. Looks like rain, freeze then snow later this week. Right now I'm -12" (from my zero line) on the measuring stick. Full pool is +54" and highest we have had to date is +5".

The FH, GS and BG are doing well. The minnow population of all sizes from 1" to 4" is insane. I stocked just 6 LM 12-14" in size in September. I've seen them cruising but have not tried to catch them yet. I expect them to be fat and 2" bigger by next summer with the unlimited food supply.

Hello - I am new here. I posted this as a different thread, but it seems like I should have asked it here instead.

I recently purchased a home in Vermont with a large pond. There is a 300 ft earthen dam with a 5ft wide corrugated metal vertical drain that runs into 4 ft wide horizontal drain. The metal pipes are in disrepair. They are rusted and full of holes. In addition, the LLO is inoperable.

The total pond area covers about 8 acres. The average depth is probably 4-6 feet. The deepest point is probably about 10 ft.
There is a secondary spillway that allows water to flow around the dam in case of an emergency, so I don't see the water overtopping the dam.

Is there any way to repair the spillway pipes without actually replacing them? I am told digging out the pipes and putting in new ones would be extremely expensive. But I have also heard that liners or PVC can be used as an insert to repair.

In addition, I am also wondering how to fix the LLO, since that prevents lowering the pond depth in case of an impending storm.

The state is also asking me to get soil testing & water inundation testing done. I would really appreciate any advice or contacts for inexpensive service providers.

Please help. All comments are welcome.

Wow, a 4' diameter culvert. That is a big outlet.

Is there a small creek that runs into your pond? Or do you have a gigantic watershed (drainage area) for the pond?

Why is the state involved? If your rotten culvert collapses, there is a very high probability that the dam would wash out and send all of the pond water volume downstream. Are there any humans or habitations at risk if that happens?

Sorry for the bad (apparent) news.

I am NOT a dam expert, but I believe that it would be very expensive to replace a culvert style outlet of that size.

If you had a 10" diameter outlet, you might be able to block the downstream end, fill it all with cement to remove the collapse risk, and install a siphon-style water outlet to handle your heavy rain events. That would be prohibitively expensive at the apparent sizes that your pond dam requires.

How large is your pond in surface acres? What is the average depth? What is the depth at the deepest point? Is there an emergency spillway?

If you add that information to your post, then hopefully some of the experts will chime in and give you some helpful advice.

P.S. You should probably go back and delete your other post, so all of the responses are consolidated under this "active" post.

Good luck getting your pond back into good shape!

Hello -

Thank you for the response and I appreciate your reply. I will edit my post so it includes the information you suggested and answers your questions.

Welcome to the forum! I've had a long day and can't figure out what a LLO is. Can you elaborate?

You could have a company put in a coffer dam around the rotted culvert, replace it, then pull the coffer dam. I have no experience sleeving something that big.