Pond Boss Forums INTRO Questions & Observations Pouring Cement Under Water

Some pier repair projects turn out so well you just have to brag and share the experience.

For all you dock builders and repairers.... You can pour cement under water if you make the pour in one continuous pour.

Wow... three pours in one sentence.

Two years ago, I needed to raise a submerged pier support by 16 inces. It was under 8 inches of water at the time. The submerged support is a three feet by three feet by three feet cement pad supported by and attached to a three sided riser.

I built a 2 ft. by 1 ft. by 16 in. high metal form.

I cleaned the top of the submerged support with a wire brush.

I placed the form onto the submerged support and placed bricks and blocks around the form.

My son and nephew brought the cement while I held the form in place. We made the pour in one smooth operation without any problems.

We then placed a pre-drilled oiled board across the top. We placed bolts in the holes (thread side up) and then stacked cement blocks on top of the the board to hold the bolts upright and keep the form in place.

I had an out of town job and didn't get back to it for three weeks. When I removed the board and forms, the new support was perfect. It was tightly bound to the original submerged support.

It was then an easy job to bolt the new pier base to the two studs sticking out of the cement.

Looking back I could have gone an easier way... I could have cemented four 8 by 8 by 16 in blocks together and left the center spaces hollow. I could have let them dry and then just filled the four empty spaces after I set them on the submerged support. It would have been easier than building the metal form.

I am sure this under water pouring techinque will work for raising and strengthening existing posts if you first put a large pvc pipe around the post and drive the pvc into the mud. The cement will not stick very well to the post unless you clean the the post or perhaps nail some spikes into the post.

Has anyone out there tried this?

By the way, the cement bible states you should not pour cement underwater when the water is less than 45 degrees F. If you have to pour in cold water you must you must measure the cement temperature and pour when it is between 60 and 80 degrees F.

Also, you should not tamp or try to compact cement poured under water.

The folks at Kaw lake marina need to hire you, that dock is a mess.

Dennis, we are working on a small 6 acre lake that has a breach about 4 ft below the water line at one of the bottom corners where the overflow square concrete structure mates with the exiting round concrete culvert: Have you had any experience with pumping concrete on the water side of a small breach and successfully stop the leaking? The leak is significant for this small a lake... about 100GPM. Thanks.

Mike,

No experience with that but when has lack of experience stopped an old man from giving advice...

I suggest you go to the library and view a copy of "The complete concrete, masonry, and brick handbook" by JT Adams. ISBN 0-668--04340-7

In my copy, a short Chapter 13 (of course) is dedicated to underwater pouring using three different methods.

The book has a nice drawing of the tremie method and the book will provide a lot of information on cement.

Method one is the the Tremie method where you make a form and then use a large pipe with a funnel to fill the form from the bottom upward in one smooth pour.

Method two is the bucket method where a bucket with a drop bottom is used. This is for deep situations.

Method three is the sack method. Used for emergency to slow and perhaps stop a large leak. A 1 cu. ft. jute sack is filled 2/3 with wet cement and are placed on the leak in a layer followed by a second criss cross layer and so on.

The book makes notes that current needs to be less than 10 ft. / minute for best results.

For a sack method, I would use a "hot" cement mixture of a half bag of portland and four five gallon pails of small grain clean sand. Use very little water to get the mixture stiff but plyable. This will be a strong mortar that should be very moldable and should allow you to pack the sack diretly on and around the crack. When dry, it is a water proof mortar.

Of course the Tremie method with forms is best and you can use a standard concrete mixture with gravel with this method.

Building forms for an angle pour is tough so I
would try the sack method to slow the leak down to a point where benonite could be used. I would use small bags (cut a gunny sack to fit your need). Perhaps even a sock or nylon hose for a very small crack?

I would clean the existing cement and crack with a wire brush and try to pour a bucket of cement directly into the crack pack as much mortar into the crack by hand. I would then quickly follow with a bag of mortar directly onto the crack.

If the flow is reduced enough, I would followup with benonite. If the flow is still too high for benenite, try the sack method again.

It should only take four hours of total time to try the quick fix method.

If the quick fix does not work, try building a metal form and use sandbags around the form to hold it in place then use the TREMIE method to fill the form. I suggest using tin, wood strips and screws to build the form. You may have to be creative and make the forms with flaps that you can load with sand bags to help keep the contrapion in place.

Regardless of the method used, after you stop the leak, you may want to consider excavating around the drain pipe after everything drys out. You may need to pour a anti-seep collar or cement "ring" around the stand pipe to prevent a straight shot for water to flow along side the stand pipe.

WARNING: There may be some large voids in the dam so be very careful moving anything heavy across the dam. We almost turned a back hole over and into a pond when a fresh beaver den collapse while driving across my dam. The beaver escaped and I was carrying a pistol, I guess I was too busy praying to get a good shot off.

A post hole digger may be a safe way to determine if there are any large voids.

Please let this site know what you do and how it works out. I am sure there are a lot of leaky overflow pipes.

Haus,

I agree 100%. It is a situation where the project is much larger than the pocketbook.

Kaw has several landings and two marinas. I like the Pioneer Marina just east of Kaw City. It is pretty well hidden and the cove is well protected.

Are you aware we have 3 lakes around Ponca? Sooner is just eitghteen miles south and is stocked with strippers. The city lake, Lake Ponca boasts some 50 lb cats and rumor has it there are some large walleye. Personally, I have never caught any walleye but they may be smarter than I am.

The three rivers in close vicinity are the Arkansas (AR - KANSAS), Salt Fork, and Chikaskia. The rivers require a small fishing boat or canoe. There is good fishing in all three lakes and all three rivers .... if you know where to go.

We Okies see a lot of you Yankees visiting Kaw Lake. What part of Kansas do you live in?

I have noticed there are some really fine sand pits up around the Wichita area but I have never fished any of them. Have you?

Thanks, Dennis. Who would guess that great tips on cement pouring are made available on a Pond and Lake forum...

Dennis,
We live in Mulvane just South of Wichita about 15 miles right off I-35. I lived in Kaw city for a summer a few years ago spent most of time sailing around the lake and doing a little fishing on the side.

Most of the sand pits have been fished out years ago.

Us Kansas “Yankees” have to go South to find any water, after all our definition of a Kansas lake is “ a pot hole full of water “ and our State tree is the “telephone pole” .

I've had good luck pouring concrete into water as well. I dammed a creek on my property starting with bags of concrete laid as-is. I used some plastic to prevent leaks initially.

Over the winter it began seeping around the sides, despite my efforts to stop it. So, I further opened a leak to allow the water level to drop for repairs. Then I used mixed concrete to cover the dam with a layer of concrete, into which I laid a few nice rocks for a natural look. I then created a temporary berm to minimize flow around the sides and front of the dam where I wanted to add concrete, then I just poured the dry concrete where I wanted it on the loamy sides of the creek bed, right into the water and above. It takes longer to set, but it does set. Then (after that set) to seal the leak, I poured a couple of bags rather quickly into and around it and it sealed right up. Very soon the water was flowing over the top through the spillway again, and I have increased the size and depth of the pond and the volume over the top, which makes a nice waterfall into the receiving pond below.

You don't intuitively think of concrete setting up under water, but it most certainly does, right, Dennis? It's not paper mache! I would think this method would be useful for certain types of leaks on larger pond dams as well. I don't think it would have worked without the foundation of laid bags being there already, though.

Many thanks again to Bob L., Ric, and the rest of the crew.