Pond Boss Forums POND CONSTRUCTION Selecting a site Pond build questions

Lots of great info here!

I'm trying to build a .5 acre pond and have a few questions about my particular situation.
I have a low area in back of my property that stays wet most of the year except in summer and droughts. I am considering a groundwater pond and have a few things I can't work out in my head. I have had no luck finding highly skilled builders in my area so here I am.

Is it possible to build a ground water pond on a slope requiring a dam or will water just flow under dam no matter what? Dam should be about 6 to 8 ft high.


There is a drainage ditch next to one side of the pond site. Will water just seep out to the ditch from the pressure of the water in the pond? Should I route the ditch to the pond to eliminate that? It's a private ditch used to drain the fields.

Digging test holes today to see what's down there.

Thanks

Yes, dig your test holes!

Are you sending some of your soil samples for actual analysis, or doing a "poor boy" analysis by yourself?

You need clay at your location to build a dam that will block the water in the pond from moving downslope. Likewise, you could even have an excavated pond with the sides and bottom lined with clay for sealing. Both of those types of ponds rely on surface run-off water as the source for the pond. A true groundwater pond will be a little more complicated to evaluate.

If by yourself on your test holes, then you can still test for clay. When you get down to the wet material that looks like clay, try and make a mudball of clay in your hands. If you have decent clay, you should easily be able to make one the size of a golf ball. If so, then take about half of that and try to make a clay "worm" between your palms. If you can do that, then you have really good clay available!

Don't worry if you can feel sand grains on your palms. Some sand in your clay is just fine.

The reason groundwater springs and ponds exist, is due to layers of porous and permeable material in the ground. These are typically sand or gravel layers. These layers are beneficial for groundwater ponds because they supply the water. These layers are detrimental for just throwing up a dam, and would cause your pond water to leak under and around the dam. That is why a properly constructed dam requires a core trench of compacted clay.

Look for these layers of sand and/or gravel in your test holes.

A seasonal wet spot on your property, could be due to either groundwater OR surface water collecting in a low spot. Your test holes may help in answering that question.

I have attached a pond construction handbook for you. There is some very technical information, but most of it is an excellent description of all of the basic factors to consider for building a pond.

Pond Construction - USDA Handbook

Good luck on your pond construction project!

Thanks for your reply!

One hole 6 feet deep so fat. Top soil1 foot. Then a hard shelf of what looks to be some type of shale. It's a rust color and the skid steer just glides across it taking small chunks until it finally breaks off. About a foot thick.
Then about 2 ft of red sand clay that ALMOST packs enough to roll it but breaks apart if squeezed.
Then a white sand clay about a foot.
Then a blue sand clay.

That's where he stopped.
Going back to get excavator now.to go deeper but it ain't looking good for Clay.

Water is coming in from the sides from the shale layer all the way down.

The area I want the pond has a decent fall to it so unfortunately just digging a hole and letting it fill won't work without a dam on the low side.

The blue clays generally pack fairly well. Try packing some samples from that layer.

From your description, it sounds like there was zero water above the shale layer?

Shale is usually an impermeable rock, UNLESS it is fractured or has developed a joint system.

Water coming in immediately below the shale layer is very interesting. You may have something called a confined aquifer.

Are there hills or substantial higher ground in the vicinity that is at a higher elevation than your property?

How large is your property in acres? You may be able to save a lot of time and effort by siting your pond in the optimum location.

The shale was confied to a small area fortunately.
Dug 3 more holes about 12 feet deep within 60feet or so of 1st hole and never hit it again but could see traces of it.
Pretty flat here. I need to put my laser on it but the house is about 6 to 8 feet higher than where it levels before the creek. Probably 400 feet away. It's the highest property in the area actually.

Interesting about the blue clay. Last holes there was top soil then about 2 foot of white sand then the blue sand. Water is coming out the white sand but not the blue. All of it is really damp though.

Something is keeping this area wet. Just need to figure out what it is and make it work for me.

16 acres total with half being the low area.
It does level off before the creek so that would probably be the best area for groundwater but I wanted it closer to the house.
But I want a pond so watcha gonna do?
Thanks again for the input

OK on the 16 acres to work with in total.

Does your property have a big slope? I am a little confused by you saying you are the highest property in the area AND you have a creek. Those two thing usually don't go together.

With water coming in from the white sand, it sounds like you may have the possibility for a groundwater pond. However, I am a little worried about the creek. It is quite common for the water level in the creek to be the main indicator of what your approximate water level would be in a groundwater pond.

Did you leave any of your test holes open, or did you backfill them? It might be good info to check the water levels in the morning.

Yes the property slopes from the house down to creek.
I meant to say the house sits on a high spot. The back half or property is as low as surrounding area.
2 pits are still open and we're continuing to fill as of sunset.

Creek is small. Maybe 3 to 4 foot wide normally and 5 foot below grade with a water depth between a few inches in dry season and a foot or less on average rest of year.

Hey, welcome to PB.

Building a groundwater pond on a slope with a dam is possible, but proper engineering is crucial to prevent water seepage under the dam. Compacting the soil and possibly installing a cutoff trench can help mitigate this risk. Regarding the drainage ditch, it's advisable to route it away from the pond to prevent water seepage. This can be achieved through proper grading and diversion channels. Testing the soil through digging test holes is a good initial step to assess the feasibility of your pond construction. Consider consulting with a professional engineer or pond builder to ensure your project's success and compliance with local regulations.