Background....I have a 6-7 acre pond, 25+ feet deep at the levee. 8 years old.

I used an 18" culvert (which was what NRCS said was the recommended sizing for my watershed) upon construction and have regretted it ever since. Since construction we've had no less than 5 '100 year' rain events, and I've almost had water running over the top of the levee 3 times. I have a very large 'emergency' overflow that pretty much gets used once or twice a year now.

To make it worse, last year I had a big rock wash off my levee and into the culvert, essentially blocking it 80% or so, about 8 feet down. Nothing I've done so far has been able to get it out.

That's where I stood as of this weekend. I burned off the back side of the levee as I do every other year, then went in and cut/sprayed some of the saplings and brush that grew in - in the middle of that effort I found what is essentially a 50-75 gallon sinkhole about halfway down the levee - right in line with the culvert. I had the guy that built the pond for me come look, and he agrees something's going on there. He's going to come out and dig up that spot and see what he can find.

So with all this, here's my plan as of right now. I'm going to have him remove the 18" culvert and put in a new 24". I figure between the increase in rain events, the rock and now what appears to be some sort of leak, I'm going to take that as an omen.

He's telling me he can take it out and replace it without having to lower the pond level. I had assumed that wasn't the case.

Thoughts?

dlowrance....I had my drain pipe replaced last year. It was partially collapsing we believe due to lots of extremely heavy logging trucks and cement trucks during construction driving over and over the dam. My pond is about 4 acres. I assume each pond might be different, but they didn't have to drain the pond when they replaced the pipe, but they did wait until later summer when the water level was at it's lowest.

Hey Zep, my shoreline grass is beginning to look like yours in that last picture. How are you maintaining the grass down to the waters edge? Weedeater? Mine is too steep for a riding mower.

Flame....weedeater on dam water edge. btw...I saved thousands on mowing last year allowing my neighbor to place 6-8 mules on the upper part of my property.

Thanks Zep. I guess I will keep weedeating.

Mark that looks great! I thought about doing that when my contractor was out but the $$$ scared me off.

Any concern about weakening the dam where they dug the trench?

FWIW, I rented a backhoe and did a DIY culvert repair at the cabin property.

http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=459125#Post459125

Lance the guy that re-did the dam pipe is the same guy that built the pond. So even-though the pipe was 1 year out of warranty he did the labor for free....I did have to buy the pipe...but since the labor was free it wasn't terribly expensive. He was already doing road work so that helped with him throwing in the dam work.

As far a weakening the dam, he didn't seem very concerned, but we really didn't have any choice in the matter. The junctions on at least two sections of the old pipe were "buckling" so as water would go down the drain the junction buckle had a lip that was allowing water to seep under the pipe which we felt could be a danger over the long term to possible dam blowout.

I've never messed with a siphon. Just wondering why we put drains through a dam if a siphon will do it. School me.

Dale- why wouldn't you install a siphon drain? Have him seal off the old one.

I'm with Dave on this one - no real experience with a siphon. What's the pros/cons as compared to a culvert?

Pro that I see in your case is the pipe is only buried enough to be able to drive over it. You never have to worry about it leaking the entire pond out because it isn't buried deep like the one you have. Or perhaps yours isn't deep? Is it just a culvert across the top surface of the dam?



The other benefit it has is that it takes lower water out of the pond instead of the surface. Usually lower water is of a less desirable quality.

Update to this string - I'm just shy of 24 months with the new oversized culvert and all is well. Even with all the big rains we've had this year the new 24" culvert is doing the job. Haven't seen it run more than 1/2 full yet. So my advice to anyone in the planning and construction phase of a pond is, use NRCS to calculate your max size needed, then go bigger than that.