Pond Boss Forums POND CONSTRUCTION Building a dam Wet Spot on New Dam.

Hello everyone, this is my first post on the forum. I just completed my pond build last November and the information I got, from the experts on this forum, was extremely helpful. So thank you for that. Below you will find a little background information concerning my pond and current situation. Hopefully you guys can put me on the right track to get this issue fixed. I will provide photos when I figure out how to get them less than 2MB.

The pond is located in northwest Indiana and is approximately 3/4 acre. Water source is a small creek that only flows when it rains. The pond captures water from approximately 45 acres. I constructed a dam using heavy clay sourced on site. The dam is 40 feet wide at the base, 20 feet wide at the top, and approximately 40 feet in length. From the top of the dam to the bottom of the creek is approximately 12 feet.

The over flow consists of a 48inch catch basin with a 36 inch offset cone attached. Connected to the bottom of this catch basin is a 12" black plastic pipe. Pipe is double wall (smooth on the inside, corrugated on the outside). The pipe travels under the dam for 40 feet and the empties into the creek bed.

An inspection of the pond yesterday revealed a wet spot at the bottom of the dam. The spot is adjacent to the pipe and is approximately 24" square. I'm not seeing any noticeable creep or erosion. No flowing water yet..

I was considering extending the pipe another 5 feet and pouring a 12" thick retaining wall, with wings, maybe 4 feet high. Then backfill with more heavy clay. I would also drain the pond and use bentonite on the front side to help seal it. My thought is that the wall, if built correctly, would stop creep and erosion of the dam. I'm really trying to avoid digging the dam.

I welcome your thoughts and recommendations.

How much drop does your pipe have from the entrance to the exit? I ask because this may affect your planned solution. If there is very little drop, it could work, but is there is a lot of drop, I expect the water will find another way out.

Hello and welcome to the forum. I help my Pond Boss family seal dams and ponds nationwide - my time is free to my PB Family and I can help outline your options. Feel free to reach out anytime tj@hudlandmgmt.com.

TJ

RAH, thanks for the reply. There is very little drop from entrance to exit. Probably 1/8 inch per foot. I see your from my area. Do you know of anyone capable of looking at my project? I'm already 10k into this project and think it's best to get some expert eyes on the situation. I tried uploading photos but the 2mb size limit was an issue. Thanks!

Awesome, I will email you.

Hoosier367, how did you connect the sections of double wall pipe together?

I do not know any expert pond builders in my area anymore. The fellow who built my first pond retired and my second pond took four contractors to finish up. I built my third pond myself and am working on my fourth even though I would rather hire out the work. Ponds seem to be out of the wheelhouse for most excavators, even for those who think otherwise. BTW, I go with the green sewer pipe for my pond drains even tough the double-walled corrugated plastic pipe is cheaper. Actually, I had the 40' of corrugated stuff replaced in my second pond after the first contractor installed it with such a belly that you could see no daylight through it (I reused the corrugated pipe as culverts on my place). The pond builder on my first pond installed the 80' pipe so straight that their was barely a "moon" showing when you looked through it. I used a string to straighten the pipe trench on my third pond, and the pipe ended up very straight. Wish you the best of luck getting your dam repaired. It might be best to draw down the pond and have the pipe replaced my a drain guy, but with construction in such demand right now, it might be hard to find someone who understands the importance of packing th pipe well with clay.

Were anti-seep collars installed on the 12" pipe?

This publication explains a more modern alternative to anti-seep collars.

https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs144p2_045869.pdf

Esshup, the sections friction fit together with a rubber gasket. It was a pain in the ass to get them together. You think the joint is leaking?

No they were not.......

I have an anti-seep collar on my first pond, but not my next two ponds because they stopped recommending them. I will not put one on my fourth pond either. Packing the clay very well around the pipe is the key to keeping seeps from forming next to the pipe. Opening up the trench wide helps ensure the underside of the pipe gets packed well. Digging the trench with the hoe perpendicular to the pipe trench pretty much ensures it is wide enough to allow the clay to be packed well with the bucket. No leaks in my first three ponds, but time will tell on my fourth pond. Have run into more water-filled silt layers on this one and they worry me.

RAH, yea I didn't use collars. My thought was I had excellent clean clay that packed nicely. I also thought that the corrugated exterior of the pipe would act like a bunch of "mini collars". Also, the bottom of the catch basin where the pipe attaches is not exposed to open water. The basin is almost completely covered in clay.

Perhaps there is a spring outside of the core, but that may just be wishful thinking. I think the exterior corrugations may leave air gaps when trying to pack in the clay, especially on the underside of the pipe.

I think you may be right about the air gaps. Live and learn I guess.

I used some of that stuff for culverts under trails with poor success, but I did not have the equipment to pack it correctly with the right type of dirt. I am still adding concrete to stabilize things. Having an old backhoe and a small dozer has really changed what I can accomplish. Hoping things work out OK for you.

Sounds like a simple and cheap solution exists - call me Friday, happy to help. We've addressed leaking overflow pipes with great success many times - they're the easiest projects to tackle.

Maybe if during the compaction process the sections were pulled apart a little bit, but that is only a guess. Give teehjaeh57 a call. he has a good solution.