Dam on pond Problem

[bob_cville]

Greetings We bought a property earlier this year with a small but deep pond. (maybe 1/2 acre by 30 feet deep) The pond level has been steadily going down. I assumed it was because we haven't had much rain, but just today I found that the pond drain line at the bottom of the dam has a 3" brass gate valve. The housing of the valve is cracked, probably from freezing, and water is steadily pouring out.

Is there any way to stop the leak while the water is pouring out?

 

[bob_cville]

Sorry if this isn't the right forum here. Maybe it belongs in the well forum or the irrigation forum since it is not an indoor plumbing problem, and the water isn't really under pressure, but the depth of the pond and the drop to the valve give a pretty good simulation of water pressure.

The crack is about 3/16" wide by about 1 inch long along the part that goes up toward the knob of the valve. I'll post a picture of it if I can figure out how.

 

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[SteveW]

Sooner or later one of the pros will respond.
Yes, post a picture -- that will help.

 

[Alternety]

I believe there are some "putties" designed for underwater use. Without a picture I can't be definitive. But a combination of the clamp below and underwater epoxy could make a decent patch. Clean around the break with sandpaper to improve adhesion.

If the fracture is in a straight piece, you can try clamping a patch over the crack. Cut some manageably thick sheet metal, get some of the stainless hose clamps that have a screw to tighten the clamp. Take the sheet metal and make a cylinder a bit larger that the pipe diameter. Set up the patch cylinder with at least two clamps on the pipe. Get it compressed to just a bit larger than the pipe and slide it over the crack. Tighten clamps. Get dry clothes.

The simplest solution is to find a scuba diver (or just someone that can hold their breath long enough) to go down and block the intake pipe. Then open the drain valve to relieve pressure and make the patch described above. If you can get the water flow down enough, you could braze the crack. Or, if the installation permits, cut that section off and install a new valve. After whatever you do you might want to put a well insulated box around the valve/exit pipe. Worst case, heat the box a bit when necessary. There are defrost wires to do this.

 

[Jadnashua]

The water at the bottom of the pond IS under pressure, just like what happens in a water tower...at 0.43#/foot depth. Whether you can get the thing sealed or not, most products are not designed for that job. It would be best to replace the cracked part, but that might require someone that knows scuba.

 

[Alternety]

Just curious if you managed to fix the problem.

Of course there is a pressure head from the water above. Hence; diver. You might be able to make some sort of long rod with a useful plug to reduce drain pressure. But if you don't know what it looks like down there, you probably won't be real successful without an eyeball or maybe a remote camera taking a look. If you can see, an air hose to blow away sediment and debris may be enough to apply a block of some sort.

But what I suggested should allow at least a temporary fix. You did not explain what "housing of the valve" meant; I assumed it was the input connection. A photo would go a long way.

Anything other than the pressure patch I described on the pipe section is going to require significantly more complicated resolution. Most will require blocking the intake. If there is enough length of pipe exiting the drain to the valve, you might get away with using some dry ice to freeze water upstream of the valve to make a repair. If you got the pipe frozen, you could just saw off the valve and braze/solder a new one on. You would have to be careful not to make a new pipe rupture with the dry ice.

 

[bob_cville]

The problem is not fixed, but I have managed to patch it to make it less of a problem. By using epoxy putty that claimed to be able to set up under water, and some fiberglass tape to hold the epoxy in place, I have managed to reduce the leak from about 1-2 gallons per minute to about 8 oz per minute.


This is a view of the dam:

This is the area at the bottom of the dam where the overflow pipe and the drain valve are:

This is a close-up of the drain valve:

I didn't manage to get a picture of the valve that shows the crack, but it was about 3/16" wide and maybe 1 1/4" long. The epoxy putty and fiberglass tape is mostly blocking the leak, but the remaining leak is traveling through gaps in the mesh tape and blocking it further may not be possible.

Someone suggested unscrewing the valve from the pipe, then screwing a new one on with the valve open, and then closing the new valve, but they cautioned that if the threads of the PVC pipe end are damaged the new valve may not screw on or might leak. Someone else suggested opening the valve (if possible) and inserting an inflatable test plug into the pipe and then quickly inflating it. Both of these seem like very wet solutions, where if it doesn't work the entire lake will drain.

Several others suggested having a scuba guy take a look and somehow block the drain in the lake, but I'm not sure how to find a scuba diving plumber.

 

[Jadnashua]

The water pressure will be about 0.43#/foot elevation from the water surface to the drain valve, but you'll have a HUGE volume of water flowing at that pressure. I wish I could help more. Have you contacted an actual plumber to see what suggestions they may have? Now with some pictures, one of the pros here may have some ideas.

 

[bob_cville]

This is an artist conception what the crack looked like:

 

[Jadnashua]

While VA doesn't get as cold as places further north, it sort of looks like it cracked because of freezing. So, whatever you do, unless you can protect it, it may happen to the fix as well.

 

[Jadnashua]

What would probably end up working better is a new drain pipe/valve, where the valve body was underwater with a tall handle. Then, the pipe would be dry unless draining, and with the depth of the water, almost certain to never freeze. Now, how to do this without draining the pond, I don't know.

 

[Alternety]

I can see the difficulty in containing the leak. But I don't think your approach was very good (not trying to start a fight - it did not work). You needed a more robust solid containment material for the epoxy to resist the pressure until it was set. That was why I suggested sheet metal and clamps. You might try again with a modified approach.

Same idea. Epoxy (or something) that cures and sticks in wet environments. A putty form is probably best. When you look for a material, you are going to have about 0.433 X depth in feet pressure on your work area. Depth is from water surface and included any drop in the drain to get to the valve. Use sheet metal and clamps. The clamps will not work well with the position of the crack. Make some pieces of wood to hold the sheet meal tightly against what you have now. Then close clamps to cover the area still leaking. I think I remember seeing tapes for this sort of task. But now you need to cover all of the various leak paths caused by using an essentially permeable tape the first time.

I believe your drain pipe is PVC. That limits repairing the brass crack to non-heat solutions.

We are pretty much talking about a temporary solution here. Although, if it works out well, it could be permanent. If you are really going to make a permanent fix, you really need to find and temporarily block the drain in the pond. I you can't see it, opening the valve and watching where the water and gunk in the pond is going can help. And it could be buried under much gunk. But a note of caution: Gate valves (what you have) are rather unreliable. You may get it open and not get it closed. You will be sucking out a lot of crap from the pond bottom. If the initial builders were clever enough, they will have the drain above the sediment level. Your drawing shows output threads. I would put an additional valve on there before trying to flush out the location of the drain in the pond. I suggest using ball valves. The are more reliable and available in PVC. When you find the drain, mark it for future reference. Maybe a little sub-surface float.

You don't need a scuba qualified plumber. Just someone who can go look. And stick some sort of cover on when you know what it looks like. If you can find someone with an appropriate video probe, no one has to get wet until you place the plug. Remember, if you get something to seal the drain, water pressure will keep it in place. It will seal when you open the valve; and be easily removable with the valve closed.

When you get everything fixed, build a heavily insulated box of non-decaying materials. Dig back along the exit pipe. Put the valve in the box. leave sides buried in the earth uninsulated. A drain hole. This should stop a repeat.

 

[Jadnashua]

Trying to apply something to the outside of a pipe to contain a leak under pressure almost never works. As I said, if it cracked like you showed, that looks to me like it was caused by ice expanding. You need your valve where it cannot freeze. I don't know the frost level where you are. Keep in mind, insulation only slows the movement of heat...it does not generate any. A slight gap where the wind can get in will overcome most any insulation. You really want your drain valve in the pond, not outside of it, IMHO.

 

[Alternety]

But bob_cville needs a usable fix now.
I am really not enamored with the idea of putting the valve at the bottom of the pond. It will be a bitch to access. A 30' handle to adjust the valve seems somehow not what you want to do. Something closer to the bottom, we are back to the scuba driver.

If you could find a foam injector and drill into the PVC behind the valve. I really don't know how to do that. Your are only looking at around 16 psi if you have a 40' total drop. Not huge pressure. But if it worked, you are going to get very wet. If you can inject some high pressure urethane (or your favorite foam) just behind the crack, you might be able to seal the leak enough for you do a repair. See if there are any foam sprayers with sufficient pressure. You might get a foam insulator from a house insulation company to do it. I think they run at a pretty high pressure. Probably pricey to get one there. If you can find some other fast cure material (cement, epoxy that works under water ?) you can inject. Later, just dig up some pipe and cut it to put in a new valve.

Not sure about this squirting foam idea. Needs to cure stiff enough and strong enough in expanding. And you might want to reinforce the area of PVC you are going to foam if you try it.

There is still a possibility you can still work from the external patch you have done.

 

[PorcelainVacation]

You could wait until it freezes again to replace the valve... while the ice plug holds back the water.