Pond Boss Forums POND CONSTRUCTION Building a dam excavated pond or damed up creek

So I have a hillside piece of property...right in the middle of this property im putting the pond. (I know..its difficult to describe writing it...) Anyways, when I dig this pond...basicly the side thats heading down hill will be "like" a dam. Not a dug out pond with dirt all the way around it. (I know Im leaving out a lot of details...but just trust me that I know most of the basic stuff about dam building) The question I have is... Should I leave the south side compacted soil untouched, or should I excavate the south side out and refill it back in with the new fill dirt?

sorry face but i am confused by the question, is the "south side" the downhill or uphill part of the pond, or above the downhill dam or below the downhill dam? i dont follow.

are you gouging out the hillside to create the soil necessary to make the downhill side dam, or are you bringing soil in to just create a berm on the hillside? are you planning on building a core trench keway beneath the dam?

Yeah the "south side" is the downhill side. Not bringing in dirt. Think of it more terraced or step like then a hill side. Lets say you 3 got steps. In the middle of the step you dig a pond. So it technically is a excavated pond...not a damed up pond. But on the other hand...if you look at it from a side view...it is damed up. make sense? probebly not..haha

Id post a pic but I have no idea how to do it.

Sounds like you'll have allot of material from the hole you dig. Using the dirt to build up a dam would give you more depth, more surface area and less digging.

If you do that, then you need a core trench and compaction.

What I'm wondering is where will the spillway be? After the dam is built, you could dig a spill way back into the side of the hill to keep it on virgin soil.

It sounds confusing,
Eddie

The spillway has a rubber liner and goes into a 3' wide flume. Basicly the question I got is..the dam itself. Is it better to construct a new dam with a core trench or leave the untouched/years of being compacted/presine soil.

Also.......At what point do I not even have to bother with a core trench or worry about the dam size? If your dam is 30-40 foot wide at the top and 90 foot wide at the bottom 1 to 3 ratio...There so much clay dirt there....Do I need to even worry? hmmm thats a good question Im posting that in another post.

Hard to answer, but generally, settled soil is fine to build a dam on. Just make sure you remove all the topsoil and any organic matter before building up the dam. If the soil is low in clay to a great depth, I wouldn't trust it.

Since you will have more dirt than you know what to do with, it's best to build the dam a little higher and a lot wider than you need it.

both questions depend on the type of soil that is there already. if you have permeable soils, you need a core trench. it wont matter how big the dam is, water will go underneath it. if you have thick clay soils, you'll probably be o.k., but you have to "connect" the native surface with the dam materials by removing the top soil (as bobad said) and scarify the surface, and blend in the dam materials or leakage could occur along the dam/native interface.

Thanks Dave in el dorado. Yeah...its thick clay soil. So I dont think I will have a problem. Of course...I will remove the top soil and vegitation.

Someone has been telling me clay soils are bad for a dam because they move & or dry out and leak? But Ive never had any problem. Either there full of crap or I have the exact dirt/clay ratio needed for a dam?

Most clays shrink a lot when they dry out, and it's common for it to show harmless surface cracks. Typically, you can dig a foot below the surface cracks, and the clay is still moist and pliable. Another good thing is, the most important part of the dam that is in contact with the water will never dry out.

face 72 --i agree with dave from eldorado i built what sounds very similar to your idea this past oct/nov. i had a hill coming down into a bottom that had a creek in it ---i didn't want to dam the creek so i created a long dam--from one point on the hill around the bottom area and tied it back into the other side of the hil---following the natural contour of the hill--it was necessary to core the dam all the way around and it was 3 ft to 6ft in places (thru top soil then sand that would have leaked pretty bad) before we hit good clay material to tie into and i'm in the middle of "clay" country. it's an expensive way to build a pond but i like mine. if i were digging it or having it dug i would have a reliable contractor in the area come out and dig some test holes along the "dam" line to see what you have to work with--and how far down you'd have to dig down to have good soil/clay to tie your core into.