earth dam for pond

[ch47dpilot]

My land has the perfect spot for a small 1/2-3/4 acre pond. There is a little stream that starts from ground water and flows most of the year. It ends up in a large bowl shaped area and then exits though about a 6ft wide x 6 ft high V before going down a pretty steep slope. My question is about how to best make the dam portion(will be in the V) and how much water does it need to get in order to stay full, I live in southern AL. It will be getting run off from about 15 acres plus the small stream(about 1 gallon every 10min at peak). Whats a good way to make a spill over? I've seen some ponds that have an overflow with a pipe that goes under the dam so the pond only gets so high. Any advice you can give me will be helpful

 

[MacLawn]

I can't help, pilot, but in my area of Georgia, they say you have to have at least 10 acres run off to feed the pond. Sounds like you have that one covered. I have a similar piece of land to what you describe, but only 5 acres, and no stream or spring to feed it. Keep us posted with your progress, and some photos would help.

 

[ch47dpilot]

will try to get some pics of the area this weekend. It maybe a while before I get to actually get the dam built, deploying to Afghanistan this summer. But hopefully I'll get some info over the next year and I'll put pics when it's done.

 

[greasemonkeyok]

If you have internet access while you are away, check out:

Pond Management - Fisheries Management - Pond Boss Magazine

There is lots of good info out there. FWIW, we have a nearby ranch where the owner had more money than sense. He spent years and high seven figures trying to get his home-made lake to hold water. He was unsuccessful, and I hear his children sold the place recently.

 

[piller]

Ponds and dams are fun projects, generally long term and lot's of work though. Look forward to hearing more info about your project. Did I read your post right, your peak water flow is about 1 gallon every 10 minutes, or 0.1 GPM?

 

[Western]

Check pondboss.com, allot of knowledgeable pond folks over there.

Keep your head down over there in Afghanistan too!

 

[TripleR]

Check with your local ASCS office to see if they will do a cost sharing and if not they should have some really good information available as to how your dam should be built as to depth and slope.

We had several built on our farms and all had the pipe under the dam to control depth. We had a couple that were built many yeas ago that have overflows over the top and two have been problematic with one blowing out due to erosion and one in need of a lot of work to repair erosion.

You can do the overflow over the top, but would need to put some fairly heavy rock there to prevent it from cutting your dam if you get a really heavy rain.

Good luck and thank you for your service.

 

[EddieWalker]

Does the water coming into the pond area start above where the water level will be when the pond is full? If not, a spring can very quickly turn into a leak!!!!

What is the soil? For a spring to exist, the soil has to be pourus. A spring is an area under ground that water flows through. They go dry when they run out of water, and will stop if sealed up or more pressure is put on the spring then what is already there. Water in a pond has been known to turn the direction of a spring.

You you need at least 2 feet of good quality clay for the pond to hold the water. If the clay is undesterbed, it has already compacted over the centuries and will hold water. When you start digging and building it, you have to compact it.

For a dam to be effective, it needs a key way. This both locks the dam in place and adds the additional weight of the new soil to gurantee that it wont fail on you.

Ideally, you want your spill way to be over undesterbed soil. If possible, send the water over to the side of the dam. If this isn't possible, then pipes and lined spillways will work. Problem with pipes is they are limited to how much water they can carry. If you get a 3 inch rain, how much water will go into your pond and how will it get out? What happens if the pipe is too small to handle the water? Will it wash out or will the water go over the top of the dam and erode it from behind? Water going out a pipe also erodes the soil where it hits it. You need a way to make sure that the water flows away and does't dig out the ground below it. Sacks of concrete and large chunks of rock both work well for this.

Pondboss has all the information that you need. You can ask the same question, and will probably get the same answers. What you really need to do is take the time to read through what is already there.

Good luck,
Eddie

 

[TripleR]

Ideally, you want your spill way to be over undesterbed soil. If possible, send the water over to the side of the dam. If this isn't possible, then pipes and lined spillways will work. Problem with pipes is they are limited to how much water they can carry. If you get a 3 inch rain, how much water will go into your pond and how will it get out? What happens if the pipe is too small to handle the water? Will it wash out or will the water go over the top of the dam and erode it from behind? Water going out a pipe also erodes the soil where it hits it. You need a way to make sure that the water flows away and doesn't dig out the ground below it. Sacks of concrete and large chunks of rock both work well for this.

Pondboss has all the information that you need. You can ask the same question, and will probably get the same answers. What you really need to do is take the time to read through what is already there.

Good luck,
Eddie

Very important consideration as this happened to us even though our ponds were built by a "professional". There were "spillways" in addition to the piping, but they washed out pretty badly. We redid them and lined them with some fairly heavy rock the full length of the overflow area.

 

[rScotty]

My land has the perfect spot for a small 1/2-3/4 acre pond.

Whats a good way to make a spill over? I've seen some ponds that have an overflow with a pipe that goes under the dam so the pond only gets so high. Any advice you can give me will be helpful

I've built a three ponds now and designed two more: one smaller and one larger. The largest is about an acre. Well, I guess you could say five ponds of my own if you count the ones that didn't work and needed to be rebuilt as two for one.....Anyway, how you build the dam or even a depression pond depends on the local soil and land and water source you have to work with. Frankly I would listen to everyone's advice, but base my final decision on local info. Chances are you've probably already got a buddy there that knows how.

What works for us here is lots of rocks followed by dirt with grass and a rip-rap spillway. Concrete spillways are slope dependent and it doesn't take much slope before they tend to transfer too much energy to the very end which leads to undercutting. At the end of any outflow put some thought into the energy of the water and how to dissipate it. On the liner or not, there may not be much point in making a clay liner for the dam if the pond bottom doesn't get one too. BTW, plastic irrigation fabric or geotextile tends to be lots easier than clay to deal with and maybe better anyway. Deciding if the pond itself should have a liner of any type is going to depend on whether the pond fills by seepage or by inflow or both. And what lives in it? For example, crayfish drill holes in clay and cut through textile liners, so depending on critters the substrate might need to be backed up with a soil and clay gradient from clay to boulders.

As for stand pipe versus spillway, you'd be advised to put in both. After all, if the stand pipe is overwhelmed or clogs - and one of those will surely happen - the lowest point on the dam becomes the spillway. You might as well design that inevitable spillway area so it won't erode. BTW, make the pipe and the spillway both adjustable for water level. That's easily done. And while you are at it, now is the time to put in a gate valve right at the bottom of the dam for draining it completely. That's very handy.
Good luck,
rScotty