I have a small 1/4 acre pond that had been grown over and wash out many years ago ... and I had it repaired. The guy who dug it for me has been making ponds for many years and is very skilled with a dozer. He finished the pond about a week ago and it was already starting to fill again and was looking good. Yesterday, after a typical rain storm, it seems to have washed out about 1/4th of the dam wall.
My questions are,
1. what caused it to happen?
2. can it be repaired and if so how?
3. should the pond guy do it for free (I paid a lump sum for the pond to be completed, not an hourly wage) or is this something that he could not have prevented?
4. any suggestions or feedback about any other topic I missed?

I have several photos and if you look in the lowest part of the broken dam wall, you will see water coming out at a steady stream. The water is coming thru the dam wall, not over it (the water has not been high enough ever since it is a new pond). If any other angles or photos would be helpful, please let me know.

Do you know how to downsize the photos? I'm very interested in looking at this but the large size make them awkward to evaluate.

Sorry, I have them at a normal size now

Are you aware that more storms are moving into your area over the next 36 hours?

http://www.erh.noaa.gov/ifps/MapClick.php?CityName=Huntington&state=WV&site=RLX

I'm just guessing, but you may be about to sustain more damage.

What does the dozer operator say?

Have you talked with other pond builders?

How about your local Conservation experts (federal and state?).

What was used for the dam? Was it good clay? Did he layer and pack it as he built? Or did he just use silt (complete with weeds, brush, trees) that had washed in and grown over the years.

Did he dig a 'core' so the new dam was 'keyed' into the old dam?

I do not think the weeds or brush would have caused it to fail unless they were so thick he could not pack it. They would have caused problems later from settling and seepage as they rotted.

Did the overflow overtop the dam?

Assuming he used good clay, I'd guess he did not do a good job of packing it as he built the dam.

The lack of a core or keying would give you a problem with seepage, I do not think it would cause the dam to fail right away.

Let us know what you find out and what solution you come up with.

Good Luck.

(Switch hit his post right before this one; alot of the ?'s are dup's, but I,m gonna leave it)

gregWV,
OK, if I am reading your explanation correctly, the water never made it high enough to hit the spillway, right? Next, are you confident that the soil has suitable clay? Where did it come from (this sometimes contains a hint)? How did the top erosion occur...was it undermined by seepage below and then washed/carried away? Next, how did your contractor prepare the bond between the old dam top and the new work? Was the top of the old scraped down to good clay? Was it then scarred, disc'd, (or cored...kinda doubt it but gotta ask) to create a mechanical bond between the old and the new? How was the soil placed and compacted...was it just pushed into place in heaps and then he ran the dozer over it...or...was it layered in about 8 - 12" layers? I assume the only equipement was the dozer...what size/type (snapshot of the type/weight of the equipment; absent compaction equipment, this may make a slight diff)
I hope fillin' in these blanks will help to prescribe.
(edit) had another thought...assuming there was decent clay in the soil, was there suitable moisture in with it? Hopefully/presumably, it wasn't dry)

Greg,

Your dam may not have been wide enough at the blowout point, notice you have limited space to damn on that side.

What caused it: Water found a way through your steep dam. I've seen backslide around here. Most people just hire a bulldozer to build a pond and the results are alot of times less than promising.
I would guess if you had a gentler slope, the risk would be less.

What does the dozer operator say?
I have not spoken to him yet.

Have you talked with other pond builders?
Yes, before I hired him, the other three all told me the same thing as far as how, just different in price. This fellow worked for the corp. of engineers for 20+ years as a dozer operator and now is semi-retired.

How about your local Conservation experts (federal and state?).
I spoke to the extension office (which I think is a part of the DNR) and they said it would be fine. When the pond guy was making it, he completly removed the old dam, then placed about 3 inches at a pass ... back and forth all day until it was build up.

What was used for the dam? Was it good clay? Did he layer and pack it as he built? Or did he just use silt (complete with weeds, brush, trees) that had washed in and grown over the years.
He moved the old dam out, and then used the clay from further back. Here where we are, the whole ground is clay... the red clay type, not the grey.

Did he dig a 'core' so the new dam was 'keyed' into the old dam?
I dont think so, he just built a long clay wall basically from scratch.

Did the overflow overtop the dam?
No, the water isnt deep enough to make it to the drain or the top of the dam. From what I can tell, like the one picture, it looks like water seeped into the damn towards teh bottom, washed out a small area, and the rest just caved in and then washed out too.

Assuming he used good clay, I'd guess he did not do a good job of packing it as he built the dam.
This is what I thought too... just a freak thing happened or it was not pack enough. In retrospect, I noticed the middle of the dam, where his tire tracks were not (in between his tracks)... was about 6 inches lower because it settled.

I agree, I think the water seeped into the dam and through it... towards the bottom of the clay dam. Then, it just washed away. Whats amazing is the water flow you see in the picture, is all there has ever been. The water flow would easily fit inside a garden hose with little pressure. There had been a large tree, which he took out but maybe the root peice was there and he didnt know it. I am surprised though that the break was about 30 feet long. I feel fortunate in some regards, the dam broke with very little pressure (considering what it would have been if 3-4 feet more water had been in the pond, which would have been filled. The dozer had a blade that was about 6 feet or so long. It was a normal dozer, not an excavator.

It appears to me that it couldn't have been well packed. If you check around on this site, there is a lot of discussion regarding the difference in packing with a dozer and a sheepsfoot roller. I think he oughta come back and make good on it.

Greg, one comment. When dealing with fixed price projects, the total dollars paid to the contractor are a substantial determining factor in whether or not the guy will fix any mistakes.

If you are talking about a few grand, I doubt that you'll get any satisfaction on the contractor fixing anything at no further cost to you.

I could be totally wrong, but from the pictures, I have to wonder if dude even really knew what he was doing. If not, you don't want him back anyway.

If it is something like $7-10K or more, you should be able to get some re-work done.

All decisions on how to correct the mistake are compared to the costs to have to take legal action. If you are successful in a legal action, you have to consider whether you will, in reality, be able to collect any money from the original contractor, and what the relationship will be like if the same guy has to re-work the project.

My guess as to why it failed is that the vegetation was not removed prior to repairing the top. Nothing will bond to grass and weeds no matter how much you compact it. Had he only a few inches to the top, it would have all peeled of when trying to cut it to grade. I am with DD, the dam should be repaired on the contractors dime.

He still has not been paid for the work he did. He completed it (so he said) about a week ago but did some other work on a smaller pond elsewhere on my land. I think I will politely insist he fix the dam since obviously it is not done and then when its done, I will pay him. I may even as that he pack it with a roller, like the previous post suggest. I would think they are fairly easy to rent, I would even pay for the rental.

Greg, the fact that you have not paid yet gives you the leverage that you need.

If this guy knows his stuff, then you can tell him to fix it or not be paid.

Maybe now it is time to consider whether you want to tell this guy to take a hike and find someone who knows what they are doing. By this, I mean, don't pay the guy at all, or give some cents on the dollar. I have no idea if your guy is good or not, but the pictues look wrong to me.

As Lance noted, the backside of that dam looks awfully steep, which makes the dam seem very thin.

Based on input and my $.02 of book smarts, here are my next thoughts. The slope of the upstream side of the dam should be no less that 3:1. The slope on the downstream side should be no less than 2:1 with good clayey soil or 3:1 where additional silt is in the clay. The pics of downstream do, indeed, appear to be steeper than 2:1. If the upstream side is similar, faux pah #1.
In a good clay subsoil at the dam, a core may not be needed, but a mechanical bond between the foundation and the dam above should be prepared. This can be done by scarifying or disking to provide a bond with the material in the dam.
What is the height of the dam compared to the top width? Here are your targets: Ht 10' = 6' min top wth, Ht 11-14' = 8' min top wth, Ht 15-19' = 10' min top wth, Ht 20-24' = 12' min top wth. All this above dimensional info spec's the ideal min mass.
Now, on to the compaction. Was there sufficient moisture in the clay soil? Could you grab a half fistful, compress it into a firm ball, and shake it violently while loose within your fingers and it doesn't disintegrate nor does water droplets fly off? Mike Otto, PB excavator extraordinaire, says to put the hand-compacted ball into a bucket of water; if it falls apart quickly, no good...if it hold together, good.
Lastly, you guessed the blade width of the dozer at 6'. This is where I ask my mentors to assist. At 6' wide, this is a small dozer...right? Tn Hillbilly would pat me on the back for this; dozers exert very little pressure for compaction. This, combined with a small unit, provides nil. You may very likely be lacking considerably here.
Wow, your timing is really something...you still have the bux in YOUR bank. M. Nature has, in her strange and unexplainable manner, smiled on you with a failure. A level-headed business discussion with your contractor is in order. Your offer to bring in the sheepsfoot at your cost is equitable and shows your intent on fairness. IMO, if the reaction is negative, time to look for help elsewhere and prepare for a lien/legal action. I hate this last sentence; I suspect you will find a fair ending...give it a fair chance. (you may want to protect BOTH parties by putting the expected results in writing).
This thread may help: dam protocol This is my call to PB assistance for a similar situation. You will also note an interesting opposing view by h2Ofwlkillr regarding successful compaction by use of only a dozer.

Greg,

I'm not a contractor and my only experience with dams dates back to my kiddy years trying to plug up small streams (with limited success) so this is only an opinion.

Your first photo may give some leads to the resultant dam failure. To me, the material used to build the dam does not look like "clean" fill. In the photo it looks like there are alot of tree roots and sticks mixed in which could provide an avenue for water to seep into the dam (you mentioned there was a large tree there). Once water gets its foot in the door, trouble will likely follow. In addition, I wonder if the slope on the backside of the dam was cleared of vegetation allowing the fill material to bond correctly. This follows the thinking stated in JBL's post.

Again, this is just my opinion. I have no right to question a cat skinner with 20+ years while my resume only reads as an armchair operator. Good luck with the repairs and keep us posted.

While I'm no expert, I think your slope needs to be more a more gradual 3/1 on both sides. The soil doesn't look like good clay either and the top of the dam should be wider. If you have a drain pipe leave it open for a year or so before you fill the pond for things to dry out and firm up. Rock line your emergency spillway and let it dry up good before it is used. The emergency spillway should be a long gradual slope and installed against undesturbed soil where the core off the dam meets it. Pack dry, Pack dry. I think he just didn't compact it well or use a gradual slope.

Mossie raises a fair point regarding my input on slope. For the record, all my dimensional info comes from the USDA handbook for Ponds-Planning, Design, Construction. aka; Pub 590
Pub 590 link
I keep a hard copy close by for reference.

On my little website I have pictures of the pond before it was touched and then a final picture before the collapse. http://www.blueridgefamilyfarm.com/

Looks to me like current is doing the damage. Maybe try to diffuse the inflow.

Even a perfectly built dam will wash if it's hit directly by current.

Happy Easter to all!

I may have found the problem. You cant really see it in the picture but where the trickle of water is still coming from, directly on top of the stream is a large rock, about 2 or 3 ft. in diameter. Could this have been the cause? My thought is that the dam could of had this rock there, the dozer is not heavy enough to pack the soil under the rock, so as the week passed, slowly the water took the whole bottom out from the rest of the dam and it just collapsed.

The rock is the absolute cause. No way he should have left it. Any pond builder should have known better than that.