Thursday, November 29, 2012
I took the photo below to show a good example of pond construction. I first designed a pond in class in college. I probably did not learn how to design ponds really well until I was A District Conservationist for NRCS. The pond below is actually a rebuild of an old pond. The old pond had silted in because of upstream soil erosion. You can see the dredged material on the left. In the center I circled the principal spillway which is an eight inch dual wall conduit. It looks similar to plastic field tile but it is much thicker. The end is cut at and angle and has an endcap on it so that it will fully charge. It is important to charge a pipe because it can vibrate so badly it will wash out if it does not flow full. The other good thing about the pipe is that it is 3 to 4 feet below the top of the dam. That will also help it to flow properly. The emergency spillway is on the right. IT is kind of rough looking, but it will do the job. The bottom of the emergency spillway is lower than the top of the dam. It is built mainly by excavation so that there is no fill material that will settle and cause it to fail. This pond is not perfect, but it has all the elements that will make it work right. Sediment entering the pond will be greatly reduced because the producer is now using conservation tillage and he has some nice grassed waterways that carry the water into the pond. There is a small sediment basin at the upper end. The one improvement I would recommend is that a dry dam should constructed on the upper end to catch sediment. Click on the phonograph to enlarge.