Pond Boss Forums POND CONSTRUCTION Building a dam Back at it

So I have been working between rainstorms this fall to do a pond expansion and change the overflow system from waterfall to structure

From This

To This

And

From This

To This

For those of you that remember my posts from last November/December .. The pond filled great .. held water, and did everything it was supposed to do and more .. The water pressure pushed the springs back and created water pockets because the water had nowhere to go, which is the reason for the expansion .. The digging was tortourous

Gave me lots of flat stone to line the sides with

Like this

If mother nature would give me a few more days of nice weather I would do some finish work and then button it up for the winter .. Windmill arrives in 3 days from Ohio .. pad is poured and water is waiting for some aeration

And here are a couple pics from late spring .. the dogs loved the water

Have some dry weather going on so took the day off and worked on the pond .. no sooner did i get here to check on things this morning when the seal around the pipe at the bottom of the concrete structure lets loose .. a fairly minor setback but really strange it did it the moment I got there .. the pond will drain .. AGAIN .. I will fix the seal ..
All is not lost .. my windmill will be put together by the time the pond is drained so I will be able to place the air stones exactly where I want them

Well Mike, better now than 2 years from now! I think you'll have another day or 2 of good weather.

A real show place.

Great to see you back on the forum, Mike! Can't wait to see the finished product. Again.

Well heres a puzzling one .. I set a 11,500 lb. cement structure at the foot of my dam .. connected it with a seal specifically designed for that application .. a couple of days ago as the pond was filling for the first time since the structure was set and I believe I encounter a bouyancy problem .. the 11,500 lb. structure shifted and the seal was comprimised .. the pond was only about 2/3 full
I never considered that the huge cylinder would become bouyant .. Ill try to post some pics

Mike,

Sorry you're still having problems on your beautiful pond. Hope you get everything worked out.

I had a waterfall idea similar to yours (but on a bigger scale) for my land. Why are you bypassing the waterfall?

This is the base of the structure which was connected to the discharge pipe

Structure going in

THAT big s.o.b. floated???

And the finished product



I spoke to the precast company that made the structure for me and they cannot believe it moved .. but it did .. and I believe it moved because of the pressure of the water ..

Any thoughts ?? Or better yet .. Any Solutions ??

From the top

I know right .. yes in a sense it did .. the precast company has suggested pinning the stucture to the pad it sits on or pouring concrete around the base essentially anchoring it to the pad below.

Mike:

What are the inside dimensions (hollow area) of the structure? I.D. and length?

I worked on a floating pier in San Diego Bay that developed cracks in it and was leaking. It was actually a 4 lane highway that was made of concrete that was hollow in the center, and it was towed down from the State of Washington. The cracks developed while it was being towed to SD. So, yes, I believe it floated.

Mike, if you can get the inside dimensions, you can figure it out yourself. One cubic foot of air will float 62 pounds. Or post the dimensions and I can do it.

Esshup .. Great info as always on this site .. the inside diameter is 48" the height is 129" .. keep in mind though (and I'm not sure that this makes a difference) that the there is a hole in the bottom to accomodate the 24" discharge pipe .. I originally, mistakenly, thought that this would equalize the pressure .. Obviously I was incorrect but I would imagine that it has some bearing on the calculation ..

FishinRod .. I scrapped the waterfall design because water travels the path of least resistance and can be diverted with a leaf .. and when water is diverted so goes the sub-base .. and once the erosion started the problem magnified times 1000 .. if 5% of the water going over the falls diverted behind one of the stones toward the top of the dam .. eventually the base became saturated which in turn softened the base structure which allowed for settling which changed the pitch of the rock which allowed more water to veer off course .. and so on and so on ..

Mike, on a quick calc, the area (air) in the pipe will float 8375 pounds.

So, unless there is more volume of air somewhere that is contributing to the lifting forces, or the concrete pipe doesn't weigh what you think it weighs, something isn't adding up.

Well .. hmmmm .. (scratching my bald head) .. I dunno

Thank you for the info Esshup .. something moved that structure .. if it wasn't water pressure .. do you or anyone else have any thoughts as to what may have moved it ??

I think my only solution is to add heft with stability .. I will order up 3 more yards of concrete, pin it with rebar and pour the SOB in place .. a yard of concrete I beleive weighs 2000 lbs... I will then cable and turnbuckle the top structure to the rebar just for good measure .. that should hold her ..

was it in there during last year's freeze? Ice floe?

no sir .. just put it in two weeks ago

Mike,

Thanks for the waterfall info, that's what I was afraid would happen on my project.

It looks like the water should just go straight downhill on your waterfall. Do you think a pond liner, then a sand buffer, then geotextile, then topped with the ledge rocks would have worked on your waterfall?

Im sure there is a way .. I thought that with enough of a forward pitch to the rocks the water would have to flow correctly .. but the spring thaws took their toll on the sub-base .. there was sooooooo much water pouring over the rocks that inevitably the water got around the edges and that was the beginning of the end ..