Pond dike design question

[VBR88]

Hello All, Name is Nate. Looking for some help. Followed EddieWalker's post of "creating a lake" pretty hard and was hoping to get some of that awesome advice about my project.

Looking to build a 2-3 acre pond for wildlife and swimming in front of my home just outside buffalo NY. The deeper the better for vegetation control.

Lot size out front is the issue, only 250 feet wide and that includes a driveway and septic line. The sand filter discharge is pushed all the way to the lot line so it wouldn't leach to the pond. The entire lot runs downhill at about a 5-8 degree slope. House is set back 2000 feet so I have plenty of room in that direction.

Guess where I struggle the most is with the level control, diverting water when building and the overflow. I will hit a spring I know it, lots of shale under me, build the house on a spring. My house drain tiles gravity flow about 2-3 gpm all year round down towards the pond. That any springs i hit and the future gutter drains should be plenty for filling and sustaining? Yes/no? Being all downhill and narrow the level control and overflow will have to be in the end where the dike is the highest. That scares me. Not sure I can do a slightly pitched natural emergency overflow. Draining the pond is a must someday to control weeds. I can't picture how to build a level control through a dike. Not sure it would be a good idea to trench through a dike and can't picture building the dike with the pipes already in the ground. Any ideas? Any advice? Any thoughts for diverting spring water out of the hole during the work? Team of trash pumps is my only idea.

I will post a few pictures of the pond outline i would like and the lot.

Thanks
-Nate

 

[sixgun]

Nate,

Give a call to the state's dam safety office. If they can't help you I bet they'll have suggestions for folks who may be able to, like the Natural Resources Conservation Service (part of the US Dept. of Agriculture) or the county cooperative extension. They may even suggest that you talk with an engineering consultant with experience in designing dams.

The dam that you propose must be able to hold water when you want it and get rid of it when you don't. There should be some sort of spillway to discharge water when the pond is as full as you want it to be as well as a drain to allow for you to do work on the dam in the future or to control weeds, etc...The spillway can simply be a section of natural ground (not placed fill) off to the side of the dam that is sufficiently lower than the top of the dam to evacuate water without letting it get too high and endangering the dam. It should also be able to withstand the forces of flowing water so that it doesn't continually wash out.

Most smaller dams like these are designed to pass the runoff generated by a "50 year storm" and still have about another foot of vertical space left before the dam is overtopped. That is a rainfall event that has a 2% chance of occurring in any given year. In NH this equates to about 6 inches or rain over a period of 24 hours. This may sound like a lot, but we've had such storms or worse here a couple of times in the last 6 years or so.

The pond drain can be as simple as a pipe laid through the dam at its base with a plug on the end that extends into the pond. You can attach a chain to the plug so that you can fish it up to the surface and pull it out when needed. The fill that you use to build the dam should be able to hold water and be well compacted as you raise the dam. Compacting the soil diligently around the pond's drain pipe (or other structures that are built into the embankment) should be sufficient to prevent leaks. When the dam is done it should be level along the top (except for the spillway) with smooth and even slopes - all of which are protected with a hearty grass cover that will keep the soil from washing away from surface runoff.

Building the dam isn't hard, provided that you've incorporated the features necessary to meet your goals and the quality control during construction is tight. Again, I'd suggest that you find someone locally that can provide you with insight and ideas.

 

[EddieWalker]

Guess where I struggle the most is with the level control, diverting water when building and the overflow.

I can't picture how to build a level control through a dike. Not sure it would be a good idea to trench through a dike and can't picture building the dike with the pipes already in the ground. Any ideas? Any advice? Any thoughts for diverting spring water out of the hole during the work? Team of trash pumps is my only idea.

Hi Nate,

You need to put in a pipe with an Anti Seep Collar on it. The pipe and collar are cheap, but the valve is where you spend the money. I put a butterfly vavle on mine because of what I read at the time, and issues I had with gate valves. Now I wonder how smart that was, and if it will work or not if I ever try to use it.

Google "Anti Seep Collar" and you will see that there are all sorts of them out there in a variety of sizes.

The collor stops the water from working it's way along your pipe, and then out through the dam. You have to compact the soil around it, but that's simple enough if you do it in layers and small amounts at a time.

Hope this helps,
Eddie

 

[VBR88]

Thanks eddie.
So it sounds like it would be ok to trench the dike for a level control/drain as long as collars are used and back filled tight and compacted.

what about doing this before the dike is built? not sure i can trench as deep as i would like once the dike is built. was hoping to go 20 foot or more with the deep point of the pond,

 

[EddieWalker]

Yes, I would do it before building up the dike. To get mine to flow, I had to dig down into the ground behind where my dam is, and then build up over it. I also used concrete to seal around my collar. I figured it was cheap insurance and once hard, it would be better then just compacting the soil. I don't know if it made a difference or not, but I don't have a leak, so who knows. Once the pipe is in place and the soil compacted all around it, then you just build up the dike in layers like the rest of it.

Eddie

 

[VBR88]

eddie
i saw that picture of your large pipe overflow under your road. (i think that is what you are talking about). saw the quick creat bags you placed around it and where you talked about driving re-bar. but where and how did you place your valve assembly. i remember seeing a photo of it with your built entension, pvc tee's, and up riser etc.

 

[babypp2]

Give a call to the state's dam safety office.

 

[VBR88]

State has no such thing

 

[MarkV]

You sure are talking about moving a lot of dirt. Where are you going to put it? It looks like you are pretty much using your available space on the property. I also see how much shale you have. Is there going to be enough clay to properly seal the pond and build a dam? Around here a pond that doesn't have a clay base is a hole in the ground that will not hold water.

MarkV

 

[SpringHollow]

Last I knew, NYS DEC will come out and design a pond for you. After the initial consultation (which I had done), there is a fee for an actual design. If you build it as they designed it, you get the fee back. I do not know if it is still that way.

Ken