Pond Boss
Posted By: Wild Flower Farm Core trench and elevation question - 12/03/21 08:01 PM
Hello everyone, this is my first post on the forum and after lurking for months I decided to say hello and become part of the community. I own a 50 acre farm in NW Florida that used to grow peanuts, and on one side there are two hills that form a small valley and stream that flows with any rain at all. I decided to build a 1-acre pond in the middle of this area for a couple of reasons. The ground there stays muddy and is hard to work so I figured it was a great spot for a pond. After having several quotes of $25-40,000 I have decided to build the pond myself. I have a 30hp John Deere with an FEL and a box blade, and so far I have been using the box blade to move all of the topsoils to the sides. Under the topsoil is really nice red clay, very compacted, very hard, and should make a good liner. The high end of the pond is about 6-8 feet higher than the low side, and I plan on making it a kidney shape where the rounded side of the kidney is about 65% dam. My question so far is, should I start the core trench at any elevation change at all, or is there a certain depth where I should begin putting a core trench in? It's a pretty gentle slope, so I was unsure where to start digging the trench. Thank you for any help!
Posted By: FishinRod Re: Core trench and elevation question - 12/03/21 09:16 PM
Usually when working with an existing topography that is conducive to building a pond, there will be a certain elevation that is the least amount of work to create a pond of X acres. I would determine that elevation first, to plan your "normal pool" water elevation level.

The acre-feet of water in the pond design must also be calibrated to the upstream watershed, rainfall amounts for your area, surface use of the land in the watershed, etc. Too little water coming into the pond is bad because it will be difficult to keep your pond a normal pool. However, it is also bad to have too much water coming into the pond.

You might actually be better off with a LARGER pond in the latter situation.

Here is a link to the old USDA Pond Planning Guide:

https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs144p2_030362.pdf

That is a very useful resource at your stage of the pond design.



It is awesome that you have good clay below the topsoil!

(Make sure you stock the topsoil so that it can be easily placed over your clay final grades that exist outside of the pond. For example, the disturbed shorelines above the water level and on the backside of the dam. It is much easier to re-establish groundcover vegetation on good topsoil compared to compacted clay.)

Good luck on your new project, and welcome to Pond Boss!
Thank you for the advice, it is much appreciated. The gentlemen I had come give me quotes actually helped me map it out, the portion that is below the higher elevation is probably 30% of the total bank. Also, I think the guys who gave me quotes realized I wasn't about to spend that much on a pond and gave me some really good advice on a plan of attack. I split the topsoil down the middle and spread it to the bank of the pond on either side, so covering the grade should be pretty easy. I also left 20 feet on either side of where I want my dam to start piling up the fill from both sides. Having finished moving the topsoil today, I plan on starting to push all the clay towards the dam, but my concern is the trench. Would making the vast majority of the dam out of clay itself still require much of a core? Or just a trench below the base with compacted clay? The pond has about 5 acres of total watershed, and from what the professionals said, I figure that should be enough for a 5-7ft pond with a few deep spots. Thanks again!
Posted By: FishinRod Re: Core trench and elevation question - 12/03/21 11:34 PM
Are you near the Chipley in the Florida panhandle?

5 acres of watershed in an arid region is not enough for a 1 acre pond. 5 acres in Florida is a much more abundant supply of water!

You are going to have to design an emergency spillway due to your chance of a hurricane level rain event in your watershed.

What equipment are you using for your compaction?
I am in Chipley, Fl. I will take the spillway into consideration, there is a large area 100 ft from the edge of the where the dam will be that is swamp and wetlands extending for a lot of acreage, 50-100 or so of swamp and washed out creek bed. So I could do an emergency spillway into that, as it already collects a lot of water around us, and most of the natural runoff of where I am digging. So I think it might dry the area up a bit until the pond overflows. As for compaction, I only have my JD 3032, I thought about just running the box blade all the way down over and over, but not sure if that would be enough. I might rent a skid steer, or if it really comes down to it, I might have to pay someone for a couple of days of dozer work for that part. Thanks!
I’m new to the forum but built exactly what your wanted my self a few years back.
2 words of advice that you do with what you like.
I’ve killed 2 3032 johndeeres. Great tractors but heavy work like that will destroy the hydro transmission ( I don’t think they make a Manuel) if they do I can’t speak of its quality.

You can rent a dozer for slightly more then a skidsteer and you will be way more productive.
I own a 333G skidsteer which is big as they come. After 12 hours I realized I needed a dozer.

As for the dam I used a track hoe and dozer.
My dam is 4’’ tall and core trench is 2’ deep.
My pond is 10’ deep.
Posted By: Pond Star Re: Core trench and elevation question - 01/29/22 11:57 PM
Don't hesitate to reach out to TJ. He is so willing to give of his time to talk thru problems or ideas on your pond -and not even necessarily to do with Soil Floc use and application. He has lots of experience and knowledge and will treat you like he has known you all of his life.
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