Pond Boss Forums POND CONSTRUCTION Soil questions Old Culvert Removal

Hey folks,

I've got a very small earthpond (30'x30') that sits along a small runoff creek. The old culvert spillway on the embankment side is rusted. Muskrats have dug several channels into the clay embankment that run leaks right into the culvert. The water table is so high that the pond has remained nearly full, but the embankment is getting ugly and I think a lot of material has been washed away.

I have a backhoe and and opperator coming over this week, but he doesn't know anything about this kind of work. But the good news is he's working for beer.

I just want to remove the old culvert completely and put a natural spillway in the trench. There are reserves of good red clay nearby.

Can you please suggest a game-plan for removing the old culvert and back-filling, while erasing the muskrat channels? Which end of the culvert should we start on? How do I deal with the water int he pond, do we darin the pond down by simply removing the culvert and letting her flow?

Any and all suggestions would be greatly appreciated, because I know so little about the power of water. At ease, the DNR has approved this project.

NyQuiLlama,

Always at ease.


This should be a simple job for an experienced operator to remove the old culvert. I would start on the end away from the water and work my way up taking the last bite out at the water. You will loose some water but the outflow in your small pond shouldn't be overly high assuming you don't run into other problems. For example, the critters may have caused damage that isn't obvious to the naked eye and that damage, remote possibility, could be tied to your digging area and take out more than just your culvert. If you suspect that is the case, you might want to rent a small trash pump and lower your water level before starting digging.

It is critical that you get good material back in the spillway and have a very gradual slope to carry off the excess water in the future.

Good luck and let us know how your adventure turns out.

Thanks for your reply Meadowlark! That makes me a bit more confidant.

I looked over the bank carefully today and I'm afraid that the damage is worse than I thought. Water is pouring and running deep into the sides and underneath the culvert, also, there are muskrat burrows that water is running into on both sides of the culvert, up to 8 feet away. I think that it's just running parallel to the bank, into and around the culvert from there, and not through the entire 15' across embankment. I hope so anyway.

I'm thinking that if I dig out the old mucky turf along the edges of the rest of the embankment, put down some clay, and compact it, it will seal any and all muskrat attacks. I can use the muck and vegitation covered soil to fill in low areas.

I also have some rubber roofing material, enough to cover the majority of the repaired bank. Should I lay that down, stake it at the top, and put a layer of gravel over it to help stop seepage and deter the muskrats, or would I be wasting my time?

One thing I should add, to help you visualize: the culvert is burried about four feet into the embankment, so this little move will raise my water level quite a bit. I've seen it at full capacity before witht he culvert sucessfully blocked, and this works perfect with the spillway.

Please provide any and all tips you can think of. I'm nervous. I might have only one shot at this backhoe.

NyQuiLlama,

A couple of thoughts by way of follow up. Seriously consider the trash pump to lower your water levels. This will accomplish two things: 1) it will make the entire operation safer and 2) it will enable you to see other damage from the critters. Thats damage that you may be able to repair all at the same time. The roofing material may help with spillway maintenance, but I doubt it will have any help with the critters...but I could be wrong.

Critter damage, in my experience, is much like an iceberg...what you can see is only a small part of the real damage. Take this opportunity to find and repair all the damage and you won't regret it. Good luck and keep us posted.

N Q L,
I agree with ML that I do not think the roof material and gravel will have any effect on the Muskrats. We have resorted to 6 foot tall chain link fence lining the inside of both dams to try to slow down the damage to the dams. They still manage to find, or dig under the fence to burrow into the dam.
Unless you get rid of all the Muskrats you will have the same problems in the near future. And, they will come back, year after year.
Check State and Local regulations so you don't get into trouble. Use the search feature and put in Muskrats and you should come up with several pasts posts on how others have dealt with 'Rat removal.

Good Luck,

Dan

The problem with running a pump is that I don't have anything that is big enough to outpump the fill-rate of the feeder creek. I think that I'll be able to make a tiny coffer dam with some red clay around the base of the culvert and work quickly to fill in the main washout with more clay, before it runs out liek crazy. Otherwise, maybe I'll just let it run out, it's not like it's going to mess up the integrety of the embankment any more than it already is... or is it? Should I dig into the embankment a few feet and re-pile and compact the soil, to try and snuff out the muskrat tunnels?

Tonight may be the night!

I would dig into the embankment until I couldn't see any more evidence of critter damage....that may mean a lot more digging and repair than you anticipated. I've seen this on my ponds, but with nutria. I tried patching, and other short cuts...none of which worked. Nothing worked for me short of doing the job right.

By the way, Mr. Dan has plans for a reportedly highly effective muskrat trap...plans which he graciously sent me some time back, but for which I still haven't built myself. Thanks Dan.

The muskrats have been gone for a year, and I don't think that they will be back. I removed all of the cattails, and acording to Tim Mattson, that's a good way to get rid of them, as it's their favorite food source. The second I see another rat I'm going to sit out with a shotgun and a six-pack. When it comes to oversized rodents destroying my property, I don't "have-a-heart."

I was actually wondering about the rubber roof liner as more of a seepage preventor. But I don't know if it would do any good or not. Anybody have any thoughts?

Maybe I'll start by digging a few feet into the embankment, before I even try to remove the culvert, and get a looksee at the washout/muskrat damage. Good plan?

As long as I get plenty of clay packed in along the dam face and in the holes that are from muskrats and the old culvert I should be fine... right?

Is there a technique for mixing the clay with existing material to make a more uniform weld, or should I just have at, fill it in, and compact it like a madmad?

There are a couple of threads on mixing the clay and I think a recent article in the magazine by Mike Otto on the same subject.

But, yes, have at it, fill it in, and compact like a madman. I personally prefer 2 feet of clay minimum, but pub 590 says that 1 foot is sufficient...two is better than one, IMO when it comes to clay.

This may be one of the more recent threads that ML remembers. It was my cry for help and input on a related matter. As most threads do, this one kinda wandered; some of the peripheral territory is pertinent to your project, NQL. damsite const thread

Brettski,

Thanks...my memory isn't what it used to be...but then what else isn't either.

Thanks team!

Although my project is much smaller, I think it would be wise for me to cut a similar core trench across my culvert hole into the embankments out to where the muskrts start cutting in.

Any thoughts on throwing the rubber roof material along the embankment helping to slow seepage? I'll bet it will help with weeds in the very least. Any negatives?

It might be tonight that we do this. Should I put the rubber roof material along the dam?

Cross your fingers for me!

Good luck! I can't see that the roofing material would hurt anything....it should keep weeds down, but I don't think it will help much with critters nor seepage unless it covers the entire pond. Just a caution to make sure the material doesn't contain anything potentially harmful to your pond environment.

Looking forward to a fun report tomorrow. I hope you don't do like I did this weekend and bury a bulldozer.

Okay, cool. I'll be sure to report back with results. If I have time I'll take some pictures, but I don't want to test my friendly neighbor's patience.

Since I promised to report back on this project several years ago I'll finally make good. My neighbor never hooked me up the the backhoe so finally last year I got a friend to do the job for $100. It worked awesome and my pond is holding all the water. The spillway works perfectly and has a constant flow of water running through it that ends in a neat little waterfall. Thanks again for all of your help!

WAIT - DON'T GO!!!

First off thanks for posting and update. Stick around, post photos, tell us about the pond.

Did you stock it?

Your screen name cracks me up by the way.

I'm still here! I've been lurking a lot lately because I need a new air pump and I'm trying to figure out which one to get from ebay (see thread here: http://www.pondboss.com/forums/ubbthreads.php?ubb=showflat&Number=215438#Post215438).

I lost all of the fish that I stocked a few years ago. I'm fairly sure that it was winter kill because at the time I had trouble with keeping the pond at full capacity do to the leaky culvert and muskrats. Because of that I only had a max depth of about 10'. Put 4' of ice on top of that and it doesn't give the fish much of a chance. Also, my pump died mid-winter. I currently have two large brook trout in the pond with about 5 million tadpoles.

But the good news is I'm back in the saddle with the old culvert gone and an excellent spillway working. Once I get a new air pump I'm going to follow the standard procedure of 15 minutes the first day, 30 minutes the 2nd, 60 the third, etc, while gradually moving the diffuser deeper. I know from when I had the pump running before that this is the single best thing you can do for an old mucky pond. The water actual smells sweet after a few weeks.

On the landscaping side of things I recently killed most of the existing vegetation around the pond margins and along my spillway (which I tried to make a natural stream-appearance with). I bought 20 vinca minor (periwinkle) plants that I'm going to stagger around along with some creeping phlox and "voodoo" sedum. I'm goign to mix all of those ground covers with some hosta, iris, and some hardy water lily. I want to create my own little slice of heaven.

I'm also planning on putting in a dock with a ladder on the end this summer so me and the kids can cool off without walking through the muck.

I'm excited to be back planning and working on my pond again. It's been in limbo for the last few years because I couldn't afford to get the old culvert removed.

I'll take some pix this weekend when I'm doing my planting. I promise that I'll post them in this thread.

Sounds great. I'm looking forward to the photos.

Hopefully we can get you some more feedback on the pump as well.

NyQuiLlama,

I just got on the site this week and read with interest about your culvert removal project. Sounds like you got your main problems with leakage solved, and you indicate the new spillway is working okay. I'm under the impression that your new spillway is just an earthen trench off to the side of the dam. If this is the case, make sure that you have a good sod-forming grass covering the spillway to prevent erosion, during heavy rain events.

However, it sounds like you have a constant flow of water through your dam, and in this case just a grass covered spillway isn't the best solution, as the constant flow of water will gradually erode into a channel that will get bigger over time. If that is the case, you will want to protect that earthen spillway by "armoring" it with rock. I'd even suggest putting some plastic erosion control sheets beneath the rocks. You will want to use some larger size rocks in some places to prevent a heavy flow of water from washing them away. Remember that flowing water has a tremendous amount of power.

Thanks for that suggestion BillSD! Actually, I've already noticed a bit of erosion at the end of the spillway where I have the water cascade a bit into a little waterfall. I remedied it by packing it with red clay and shielding the brunt impact areas with plate-like rocks. You're right that it was washed away after a large rain. I do have a constant flow of water, although it's fairly light. I have several rocks lining the spillway to create a sort of babbling brook effect that slow the flow. I haven't noticed any washout along the rest of the spillway and I think I'll be okay as it's lined with heavy red clay. Maybe I'm wrong. I have some rubber roof material I could use to line the bottom of the spillway with, but I wonder if the water would just flow right underneth it and cause more friction than without. I'll get out there sometime today or tomorrow and take some pix and post them in this thread for your analysis. I also got my new pump running so I'll post some pictures of it in action.

We have one pond that has a 15 inch sewer type pipe through it as the principle spillway. It is about 150 yds in length, but ends short of the normal draw channel. It only runs in the spring and after a heavy rain, but what I did to control erosion from the end of the pipe down to the normal draw channel was to make a field stone "stream" about 10 ft wide. We shaped the channel and then starting at the bottom end, layed sections of heavy gauge plastic, over lapping as we went up, much like the shingles on a roof. This plastic was actually just "ag bag" plastic I got for free from a farmer who was using it to store silage the winter before. Then we laid field stone in the channel on top of the plastic. Every 15 ft or so we made a sort of small waterfall by placing some big rocks across the channel. These also serve as anchor points so in a heavy flow the smaller rocks just upstream will stay put. Makes a great sound, and the water can't erode the soil underneath. Sounds like you've already got rock in place, so you may not want to go to all the work of removing them and then doing this. Just keep an eye on the soils underneath for erosion.

I think I'm going to use plastic on the end of my stream (where I have the most rapid vertical drop and thus the most erosion). We had another heavy rain and it washed out again, my red clay didn't do enough. It also didn't help that I've got a few waterfalls in the mix. My wife took the camera with her on a trip this weekend, so I'll get pictures up upon her return. Thanks again for the suggestions.