A small lake in our community that consists of a box dam and two spillways has breached due to a heavy and fast rainstorm. Luckily, the dam structure itself is fine and the only thing that breached is the dirt spillway. It's a pretty simple spillway that is really just dirt capped with asphalt and was originally constructed back in the 50's.

Although we do have larger overall plans to rehab and perform maintenance on the dam system, we would like to bring it back to where it was in the meantime. What would be the best type of dirt / gravel to put back in there as a base?

Thanks!

Clay, properly compacted, and build it with a core trench. Get it covered with something to keep the water from eroding it away again.

Here's some reading for ya.

http://www.sccdistrict.com/pond.htm

Make double darn sure that it is large enough to handle the water. Consult the NRCS office in your county for more specific information.

Thanks for the link and suggestions, exactly what I was looking for. Some people are suggesting Class 5 Gravel which I believe has a mixture of clay in it. Would this also suffice?

I've never heard of gravel and clay being used together to compact for a dam.

I agree with esshup, I would have never thought gravel would properly adhere to clay. Looking at Goggle images, Class 5 gravel almost looks like a paving/foundation mix.

Don't mess with the gravel. Use a mix of loam with about 65% clay/soil. Pure clay cracks when dry.

Sorry for the late reply and thanks again for the advice. What material would be best to use to cap the clay? It was blacktop before but like I said earlier, that was done many years ago.

Good pond builders mix the clay with dirt to create a loam mixture. Hard to believe that a dozer can do that but a good operator can.