<Howdy PB friends - been a while since I posted>

Thought I would share a couple learned lessons in ponds. For the first 10 years of ownership of my 8.5 acre pond, the biggest problem we faced was not enough rain/low water. After 10 years of focusing on not enough water, it never really occurred to me that we *may* someday have too much water. Guess I was lulled into a false sense of security...that someday was last December when we had 2 x 6"+ inch rain events on consecutive days.

Long story short, water went over the dam and the dam, as you can see from the pics below, is history. We blew out about a 40 - 50 foot section of the dam.


http://i4.photobucket.com/albums/y117/darnold01/Backside.jpg

http://i4.photobucket.com/albums/y117/darnold01/Gap.jpg

That's tough man. Is the blowout where the spillway was?

Man, that is painfull to see. Going to rebuild?

That made physically sick to see! How much watershed area do you have ? Did you have stone in the spillway? Sorry about your predicament, I hope you rebuild. I don't think it's gonna be that expensive to fix.

Sad deal.

Good reason to have:
1. plenty of freeboard to hold temporary excess water
2. wide flat emergency overflow to keep main part of dam from being breeched
3. rock or riprap covering the emergency overflow and up the sides of the emergency overflow so water does not cut an erosion ditch when excessive flow happens.

When you redo it, you can make the pond even better than before.

Thanks guys, yes we are set up to rebuild as soon as conditions permit.

The watershed is approx 532 acres.

There is an emergency spillway.

The breach happened on the opposite end of the dam from the spillway.

Sort of a long story:

I acquired the property 10 years ago, the pond was existing, probably about ~25 years old at that time. However, the original stand pipe had corroded and broke off at the base, draining the lake. The pond had basically reverted to a 10 acre swamp with brush, trees, wild animals...ect.

We hired a dirt guy & cleaned up the lake, removed the broken stand pipe and repaired the dam where the stand pipe had been. We added an emergency spillway and added a 12" siphon drain pipe to deal with normal rain events. So thinking we were all set.

When we cut in the emergency spillway & took free board measurements on that side of the dam (the dam is about 600' long). Everything looked fine and we had close to 3 feet of free board. (what we didn't realize) is that the dam had a gentle slope beginning about halfway across & sloped to the other side of the embankment. The slope is so slight that it was not visible to the eye. AKA the dam "looks" level & we didn't measure the entire perimeter when cutting in the spillway.

We did a lot of things right - but ultimately the dirt guy we hired didn't have the right experience although he had built a lot of ponds. Big difference between a dirt guy and a pond builder...

This time I hired Mike Otto to get us back on the right track...

You know, Gator, the ratio between plus 500 acres of watershed and an 8.5 acre pond means that you will have extreme amounts of water to deal with during heavy rain events. I'm sure Mike Otto will take that into account on your spillway, it will likely need to be built specially for those kind of flows.

So sorry about the problem. Hard to think about too much water when you've had years of not getting enough!

I bought a construction grade laser level when we built our pond (after an associate ran over a sub-construction grade laser I already had). I flagged it all the way around the pond with plastic flags showing where the water line would be. This gives a good visual indication of what level is.

Since we lacked experience doing this kind of work (we are farmers, not contractors), I was kind of anal checking elevations and making sure we were getting things correct. I even kept checking my flags relative against what was left of the original NRCS flags the agent set to see if what I was doing was in agreement.

Having an unexpected low spot on a dam is not a good thing.

The emergency spillway is the width of 1 D8 dozer blade, we plan to double it and drop it about a foot.

The original Dirt guy surveyed the entire water line - which is fine. But didn't re-check entire dam compared to the emergency spillway height. I've had many folks look at the dam and by eye-sight it looks level - you figure something that has been there for 30+ years "must be ok"...but not so much.

Yes, it can be deceiving. I've tried to run water up hill more than once in a field terrace channel before we got the proper equipment to actually measure grade.

What made it worse in your case is having the water low so long there was no close reference line to observe. Had the pond filled normally and got to full pool level, you might have noticed the low spot then with the water level up closer to it.

Too much water all at once never gave you the chance.

I think you will find that the e spillway needs to be about 80 feet wide, at least.

Tough loss. Sorry to see that. Got to be cool to work with Otto tho!

Mike will get you fixed. AS far as the "eye ball leveling" it just doesn't work, even for the best. Mike built me a terrace, that EVERYONE that saw it said it won't work because it is going up hill, but EVERYONE was wrong, but Mike. It flowed just like it was supposed to. Contour of the land will create optical illusions, but the level doesn't lie.

Wow that sucks. I'd freak if my damn burst. So would the vehicle traffic that it parallels!

Wow makes you realize how quick things go from just fine to really bad with damns...

Ditto....if my levee were to fail there would be some calls from the county road commission and likely the sheriff...as it'd probably wash out the road.

Gator sorry for the event but very glad to have you back posting.

Mike will do a great job. It is often amazing what we don't know until it bites us.

Thought about stocking plans and structure adds while you wait ?

Ditto here too!