Creating a Lake

[EddieWalker]

I have my rebar tied and my forms are ready for concrete. I went with 3/8's rebar on a 12 inch grid for the wall and every two feet for the angle. The footing is 3 feet deep and a foot wide. The wall is two feet tall and changes from 18 inches thick right at the top of the cement pad, to 8 inches at the top.

Tomorrow I'm third in line for the concrete truck. The forecast is for rain and it's increasing. I'm hoping that I'll be fine, but if it's gonna be close.

I'm estimating 7 1/2 yards. I'm adding extrac cement to the mix to get a 4,000 psi mix.

Eddie

 

[EddieWalker]

Change of plans. It was raining this morning and too muddy to get a concrete truck to where it needs to go. I'm thinking it's going to be a couple weeks until I can try again.

Eddie

 

[philbuilt]

I like your set up. 2 more feet of water will make the lake seem so much bigger.
Will that add about 3' all around? How long before it will rain and fill it up.
Phil

 

[jinman]

Eddie, sorry to hear about your delay. It's unfortunate that you have to deal with needing nearly perfect conditions to get a truck to your spillway. BTW, it's taken your picture for my old brain to visualize what you are doing there. After the pour, are you going to fill in the sides behind the cinder blocks?

 

[Western]

Eddie, sorry to hear about your delay. It's unfortunate that you have to deal with needing nearly perfect conditions to get a truck to your spillway. BTW, it's taken your picture for my old brain to visualize what you are doing there. After the pour, are you going to fill in the sides behind the cinder blocks?

I was wondering about a water " baffle" on the backside. Maybe thay is what will go there. Wonder if filling that void with large rock would work for a baffle and strength??. I know Eddie has a plan, just curious.

 

[jinman]

I was wondering about a water " baffle" on the backside. Maybe thay is what will go there. Wonder if filling that void with large rock would work for a baffle and strength??. I know Eddie has a plan, just curious.

Yep, maybe crushed rock or something similar in the middle. I was wondering about filling with dirt between the outside wing walls and the concrete blocks. Hydrostatic pressure is gonna push really hard against the cinder blocks if Eddie gets a big 4"-5" rain and that spillway is flowing pretty fast. I'm just not sure how Eddie plans to handle the transition between the spillway and the earthen dam so water stays inside the spillway and doesn't erode around it. Eddie has the width of a 2x4 above the main spillway for the wings, but what if the water tops this?

 

[EddieWalker]

I'm not sure if I understand the question. The cinderbloacks will be filled with concrete. There is already rebar inside of them to help lock them in position and add strength to the wall. The water will flow over the dam between the cinderblocks, creating two, side by side spillways. Across the top of the cinderblocks will be a six foot wide foot bridge.

I extended the cement dam 9 feet into the dirt and raised it 8 inches. My thought is that the water will take the path of lease resistance and only go so far along the concrete. This is all theory, and I counldn't find anything online to copy or learn from. Guess, Guess and more Guessing!!!!

The concrete is fairly stright on the water side, but angled on the back side. The wall is two feet and the bottom is 6 inchse out for a 24:6 pictch if roofing terms work. Again, this is just guessing on my part and what looked good eyeballing it. I want to water to flow over the dam and not just drop.

Where are you thinking the rock or gravel should go?

Eddie

 

[HiddenHollow]

Ed, I think they are talking about the space behind the walls on each end. There is a triangle of sorts between the wall and the wing of the dam. I belive they are concerned about all the force against the walls.

 

[EddieWalker]

Thanks. That will be filled in with dirt that will be brought up to the height of the bridge. The wings will be covered by dirt and not be visable when I'm done. I can't fill in the dirt until I remove the forms.

Eddie

 

[Western]

Eddie I was just curious about the area between the down flow, or backside of the dam/spillway, between the Block walls.

It may take some water over it to see how the hydraulics will work against the backside. That's why I wondered about the large (big) rock I've seen used to baffle the water on some Corps lakes overflow, or drain area to cut down on the hydraulics cutting back into the dam .

BTW, your walkway idea is super neat, should be handy for removing debris and inspection of the spillway.

 

[RadarTech]

Not sure how much cost difference there is... But why about using a line pump to sit the truck 30 feet or so off and pump it in....I know challenges are there but just a thought

 

[jinman]

Eddie you answered most of my questions with the last post. I'm added a labelled photo of your spillway to clarify my questions/suggestions. The 2nd drawing is an attempt to show the swirling effect of the water inside the spillway walls. As the water rolls off the spillway, it will be spinning and probably erode more than just flowing water over grass. I see on closer examination that your ends are much higher than a 2x4 width. I think you said 8" higher.:thumbsup:

I'm not sure how you will tie in the walkway bridge either. Will it touch the spillway or be tied in for additional strength?

 

[EddieWalker]

Jim,

My first plan was to just build a wall, then I thought about erosion as the water came over the wall and how it would undercut the wall. I added the pad to handle this and hopefully slow down the water before it hits the grass. I've considered spreading plastic and gravel down after the concrete, but really want to see how it works with just grass. Once my bermuda fills in, it's pretty good at holding the soil in place and the slope is almost zero.

The spillway is two feet tall, or four blocks. The bridge joists will rest on the top block, which is the fifth block up. This gives me 8 inches of height that water can flow over the dam without touching the first joist. I've worried that this might not be enough, but with the width that I have, I think I'm going to be fine. It goes back to lots of guessing on my part and seeing what's come through the spillway before when it was full.

Thank you,
Eddie

 

[bindian]

Jim,

My first plan was to just build a wall, then I thought about erosion as the water came over the wall and how it would undercut the wall. I added the pad to handle this and hopefully slow down the water before it hits the grass. I've considered spreading plastic and gravel down after the concrete, but really want to see how it works with just grass. Once my bermuda fills in, it's pretty good at holding the soil in place and the slope is almost zero.

The spillway is two feet tall, or four blocks. The bridge joists will rest on the top block, which is the fifth block up. This gives me 8 inches of height that water can flow over the dam without touching the first joist. I've worried that this might not be enough, but with the width that I have, I think I'm going to be fine. It goes back to lots of guessing on my part and seeing what's come through the spillway before when it was full.

Thank you,
Eddie

Eddie,
The dam on the 75 acre lake where my ex MIL lives has concrete bolsters stilling up at random locations on the back side of the concrete down sloping spillway. These concrete pillows stuck up about 2 feet and were big enough to sit on.
hugs, brandi

 

[pilot-werx]

Although my pond is not nearly as big, here is my spillway....

 

[Ranger Rick]

Jim,

The spillway is two feet tall, or four blocks. The bridge joists will rest on the top block, which is the fifth block up. This gives me 8 inches of height that water can flow over the dam without touching the first joist. I've worried that this might not be enough, but with the width that I have, I think I'm going to be fine. It goes back to lots of guessing on my part and seeing what's come through the spillway before when it was full.

Thank you,
Eddie

Eddie is your first bridge joist going to be at the edge of the pier next to the dam? Also do you ever get floating branches or debris that would try to go over the spillway. If you do you may want to raise your bridge up a little bit so that debris is less likely to catch on the bridge. Eight inches is not much space for water to go under the joist unless your 100 year flow is only a couple of inches. It looks like it will be good and strong.
Rick

 

[Western]

Eddie you answered most of my questions with the last post. I'm added a labelled photo of your spillway to clarify my questions/suggestions. The 2nd drawing is an attempt to show the swirling effect of the water inside the spillway walls. As the water rolls off the spillway, it will be spinning and probably erode more than just flowing water over grass. I see on closer examination that your ends are much higher than a 2x4 width. I think you said 8" higher.:thumbsup:

I'm not sure how you will tie in the walkway bridge either. Will it touch the spillway or be tied in for additional strength?

Great label job Jim, that is what I was trying to convey, I used the word "baffle", but you did a much better job. Hydraulic turbulence can do amazing things.

What I said earlier, it may take a few times of overflow use to see what will actually happen, but the nice thing is, it will be easy to add rip-rap or what not, to combat any problems that may arise.

Eddie, sure looks good brother and tough work in the muggy heat.

 

[EddieWalker]

Brandi,

That was one of my plans. But I was going to pour a straight wall land support it with three piers that would be on the backside of the dam. After thinking about what it would take to do this, I came up with putting rebar into the pad and angleing it into the dam wall. This is how I came up with angleing the entire back side of the dam. At two feet, I think I have enough strength. In fact, I kept going bigger, until I thought I'm at over kill and then some with my thickness.

Pilot,

Thanks for the picture. I love the rock and very will might use some after the pad. Trnasistioning from the concrete pad to the rock has me scratching my head, but I'm thinking of just adding more concrete there to hold the rocks together and not let the water undermine them. Here, I don't have to pay tax on river rock, so that's what I'll use if I decide it's something I need to have.

Ranger,

Yes, it will be right at the edge of the blocks, almost sttaight above the dam. There are a lot of logs and stumps in there, but very little flows to the spillway. They are all locked together in piles and have stayed in position since I built the piles. There will be some floating stuff, but I'm hoping that with regular mowing and cleanup, I should be able to handle it. Even so, I'm sure that I will have something jam into there and cause me problems. My thought is that it's wide enough to handle it without stoping water flow, and strong enough to hold it if it happens. Lots of guessing here, so the possibility of failure is always there.

Dennis,

Thanks. It's tedius and time consuming, but also fun and satisfying. I've been planning this for years, and havent' started it because I didn't have it figured out, then didn't have the time, or the water was too high. Now seems to be the time to do it, I just need some dry weather so I can get an 80,000 lb concrete truck down there safely.

Eddie

 

[mike69440]

Although my pond is not nearly as big, here is my spillway....

Nice spillway, I will do something similar with field stome and boulders

 

[pilot-werx]

my little pond is only 450k gallons and 20' deep. I dug it in a 100% clay deposit and it is fed by a few springs. The top six feet where lined with geo fabric and stone. The spillway was formed out of clay, lined, covered with stone and a slab of granite was used to control level. Many have questioned the integrity but is important that zero surface water enters the pond and the maximum amount of water, aside from rain, that can enter is controlled by a 4" pipe....