Any ideas to stop a leaking pond ****?

[Jeff244]

Thanks for the responses,


Meadowlarkponds, When the area is dug out I was planning on adding bentonite to the clay and then replace it. If it is too gravely, I will get so me new clay. Some of the pictures you saw were taken after we got about 8" of rain in an 18 period. There are 2-12" culverts that were almost covered by the water. Regarding the freeboard, at first I eyeballed it and was gong to tell you there was a good 3 to 4 feet. Luckily I decided to shoot the grades. There is about 23" to the top of the road and 11" at the spillway. The spillway is in an area that was not disturbed or filled in when the dam was built. There is no topsoil, it's all clay and of course stone on the road. I measured at the top of the stone. Do you think I should lower both of the culverts a foot or more and then see if the dam is still leaking?

Eddie, as I stated above some of the pictures were taken during very heavy rain event. The water got to the top of the spillway but never over it. The road is slightly pitched towards the dam and that is why there was some standing water on it. As far as the construction, I know that he used a large sheepsfoot roller pulled by a tractor. I don't know if it was vibratory or not.

I found some pictures taken during construction and as soon as I can get to Walgreen's to get them digitized(?) I will post them.

At some point I will call the guy who built the dam. I am trying to learn as much as I can before calling him to discuss the situation.

Jeff

 

[meadowlarkponds]

Jeff,

I guess the pictures fooled me cause it looked like a lot less than 23 inches....but, if that's minimum, it should be okay.

Maybe I didn't study the pictures enough, but did I understand you to say you have natural spillways that are cut at 11 inches above the "full" water line. So, they are emergency spillways? and the two 12 inch culverts are the primary spillways? Sorry if I'm confused...what I'm driving at is a concern that during the 8 inch rain in 18 hours, the water line got much higher such that it approached a no freeboard or only 12 inch freeboard condition....23-11 = 12.

If that happened, the hydrostatic pressure could well have been to much for the dam in that particular area....and if it happens again, you may loose the dam

If it were me, and obviously it isn't and I'm not there. I would lower the water level to take some pressure off the dam...how much? Not sure, but probably a couple of feet. Keep a very close eye on that area and if you see any signs of changes, additional weakening, then for sure lower the water level. Myself, I would be very nervous about that area and the possibility of it giving way. I'd encourage you to get your pond builder out there as quickly as possible.

 

[Jeff244]

Meadowlarkponds,

You are correct, the two 12" culverts are the primary spillways and there is one emergency spillway. Regarding the 8" of rain, the pond was already within 6" of being full and the ground was already saturated. The rain was never at a pace of over 1" an hour. If we got a rain event of 2" an hour during a heavy thunderstorm, the water would likely flow over the emergency spillway.

Do you think it would make sense to put in 2 larger diameter culverts to replace the 12" culverts(maybe 15" or 18")? I could also lower them a foot or so.

I am monitoring the bulged area. I put 4 stakes in using a level and I can check to see if they get out of level. If you know of a better way to monitor the area I would appreciate it.

Here is a couple more pictures showing the stakes and the emergency spillway.

Thanks,
Jeff

 

[meadowlarkponds]

Jeff,

Rather than the expense of replacing the culverts with larger diameter ones or lowering them, consider lowering the emergency spillway to insure you "never" have water above a two foot freeboard. That alternative would be cheaper, I believe, but more importantly would give you added insurance against those 100 rain events which seem happen two or three times a year around my place.

Whatever you decide, I think I would wait until you start tearing into the suspect area on the dam and determine what caused that to bulge....some candidates are poor compaction, poor clay content, and/or high water levels above that which the dam is designed to withstand (2 foot freeboard).

 

[Jeff244]

Meadowlarkponds,

The only problem with lowering the spillway is that I worry about erosion if (when) we get a lot of rain. I finally am able to post some pictures of the construction. The clay is very gravely, but I do know that a large sheepsfoot was used and I am told the clay was placed in layers were about 8" to 10" thick.
There are a few more pictures on my photobucket site also.

Thanks,
Jeff

 

[EddieWalker]

From the pictures and looking at the tracks in the dirt, I don't see any sign of a sheepsfoot.

This isn't something that's used all the time. Commercial and jobs that have to pass code use them, but from what I've seen, most pond builders don't. If you have marginal soil, it would make the dam tighter and more solid.

Just to nit pick, and from what I can see, that's all I'm doing. The belley scraper is making it's pass in your pics. The dozer looks to be waiting to spread it out, but it might just be parked there. If the dozer is used to spread and compact the soil, then it needed to be over every inch of the soil. If they were just dumping the dirt with the belly scraper and not working it in with the dozer, then your dam will be very loose.

Do you have more pics or details? Was the sheepsfoot a pull behind type that was towed with the dozer? A good one, and there really is only good and too small, is too big and heavy to move around with anything else but a dozer. The way it works is to be so heavy that it mixes and compacts teh soil with every pass.

Eddie

 

[Jeff244]

Eddie,

After looking at the pictures again, I also didn't see any signs of the sheepsfoot. I was beginning to wonder if I "misspoke" about it being there( I seem to remember snipers shooting at me too ). Then my wife found a bunch more pics(we are in the process of moving so a lot of stuff is in boxes). There is one showing the dozer pulling a large sheepsfoot roller behind it. My only concern is that the dirt looks extremely dry. Also, the picture you were referring to with the dozer looking like its ready to spread the dirt looks to me like the scraper is removing dirt because I can see tire tracks behind it. No that it should matter, but the job was not lump sum, it was T&M so there was no "incentive" to rush the job.

Thanks,
Jeff

PS It might be a while before we get to town again so it will be a while before I can get the new pics posted.

 

[Soundguy]

I'd draint he pond and liberally apply bentonite.. Then you can be sure..

soundguy

 

[Jeff244]

Soundguy,

I know that's probably the right thing to do, I think I'm just waiting for someone to suggest pouring some bentoite in the water and that might fix it.

Eddie,

I looked at some more pictures and I you were right, the tire tracks behind the tractor match the scrapers tires.

I called the guy who put the pond in and he is going to stop by tomorrow to take a look at the dam.

Thanks,
Jeff

 

[meadowlarkponds]

I know that's probably the right thing to do, I think I'm just waiting for someone to suggest pouring some bentoite in the water and that might fix it.

Jeff,

Someone may suggest it.....but, IMO, it is highly unlikely to fix the problem, highly unlikely. I once saw the statistics on Bentonite success rates when poured into the water; can't remember the exact numbers but it was very, very low probability of fixing anything other than very minor leaks.