Pond Boss Forums POND CONSTRUCTION Building a dam Earth or Cement?

Hello Everyone,

I've been lurking here for a while and reading up on the posts here. I've really enjoyed what I've been reading and have learned a lot. My situation is that I have just purchased some land with some geography that sounds like a dream setup for a small pond. I have a small (very small) creek flowing over a limestone bed that flows over a five foot water fall (ok five foot drizzle). The water falls into a sunken circular area with natural rock walls that is about 50 feet across. At the far end of the sunken area is an outlet stream.

I've been thinking about turning the circular area into a pond by damming the outlet stream. The dam would need to be about 5 feet high and about 10 feet wide at the top. Given everything I've read I don't anticipate any big problems like algae or cloudy water. I believe I will be able to install one of those pipes with a grate at the top that lets the water flow out and everything should be fine …. with the exception of a big rain. If we get a heavy rain (let's say five inches) the dam will certainly overflow.

So my question to the group is should I construct the dam out of cement, or is it possible to construct a earth dam with a strong enough spill way to prevent the entire dam from being washed away in the spring? The variation in flow (purely a guess) will go from something like 10 gallons a minute to 1,000 gallons a minute.

I think an earth dam would look much nicer, but I'd really like my dam building experience to be a one time event.

Thanks in advance for you help.

The problem I see with an earthen dam is how to tie it into the rock that's already there. If dirt is sitting on rock, it will wash away. If water runs over dirt, it will wash away. It's just a matter of time, water never gives up and it's allays destructive.

Concrete will be very, very expensive.

Before you do either, you really need to post some pictures to give us some idea of the conditions at the location. Your discription paints one picture, but it's probably not the same picture that you see when you're there, so we're just left to guess at what it's actually like.

Eddie

Jack,

I believe most pondmeisters on this forum are kind of partial to earth type dams.
Use good soil material for construction and compact it properly.

A 3:1 front slope and at least 3:1 back slope should suffice. Use a flatter slope for the back slope if you ever anticipate dam over topping. Plant good sod forming grasses on the structure to help prevent side slope washing and erosion.

I have been really satisfied with principal spillway (Pipe works) from agri-drain for projects like yours. Probably the "Inline water control device"
http://www.agridrain.com/

Sounds like a very nice project.
Ed

Hey Jack,

What size and depth will the pond become with your estimated 5' high dam? Would you also dig out the pond, and is there really anything to dig? If you go with an earth dam, is their any clay in your area?

Thanks for everyone's' responses. I was busy at the site clearing trees yesterday and right now the pond area is full of trees so pictures wouldn't tell the story. To respond to a few people now though:

Edward P Eitel: A 3:1 front slope and at least 3:1 back slope should suffice. Use a flatter slope for the back slope if you ever anticipate dam over topping. Plant good sod forming grasses on the structure to help prevent side slope washing and erosion.

Answer: The soil (what little I have) in the area is a mix of sandy earth, and a soft sand stone dirt/rock. I do have a few spots that have a sandy clay but I suspect as soon as I start digging I will hit either rock or sand. I have lots of rock so I anticipate no problem with the dam purely washing away but I will need some kind of barrier to retain the water.

Bobad "What size and depth will the pond become with your estimated 5' high dam? Would you also dig out the pond, and is there really anything to dig? If you go with an earth dam, is their any clay in your area?"

Answer: Within the pond area is a patch of ground about 20'x20' that is deep enough to sustain one tree that is about 40 feet high and a couple of other smaller trees. As soon as I have the trees cleared I am going to rent a backhoe and remove all the dirt I can. All of the rest of the pond area has a stone bed. I suspect that I will only be able to dig down two or three feet before I hit a rock base.

Eddie Walker: Before you do either, you really need to post some pictures to give us some idea of the conditions at the location. Your description paints one picture, but it's probably not the same picture that you see when you're there, so we're just left to guess at what it's actually like.

Answer: Perhaps today I can take a few pictures after I've done some more clearing.

Thanks again to all.

Ok, I have some pictures! Please go to http://home.comcast.net/~jack.flint/ and check them out. I have some pictures of two types of fish that lives in small pools in the stream if anyone could identify them I appreciate it.

Since I've continued to work cleaning the pond area and reading up on damn contraction my current thinking it to construct a rock fill damn with cement serving as the impermeable barrier.

I'm looking forward to everyone's response.

The top fish is a lepomid of some type. This family includes bluegill, common sunfishes etc.