Been waiting for the pond level to decrease and my energy level to increase to do a water level improvement to this pond. With rain a few days away in the forecast and the pond level a good foot below full pool because of the exceptionally hot dry weather the time had come. After watching the pond a year and considering the watershed area that fills the pond I decided I could safely maintain a higher water level on the existing dam (less freeboard space). I have done a similar exercise to three of my other ponds.
This pond has an 8" PVF overflow pipe. First step was to take the laser level and establish full pool level, dam height and emergency overflow height. I determined I could safely add 9" to the depth of the pond by installing a 90 degree elbo on the 8" overflow pipe. The vertical part of the elbo was cut down to about an inch above the top of the 8" pipe. This will give me about 9" additional water depth. I left the emergency overflow at the same level and at the new full pool level the water will be running about 4" over full pool through the overflow pipe when the emergency overflow is reached. So during heavy rain events under soil saturated conditions, the emergency overflow will really become more like just a normal earthen overflow and flow water. So the emergency overflow will likely get used once or twice a year. More normal rains will simply pass through the overflow pipe. I did cut the dam down in the emergency overflow area to make sure the flow area width was very wide and could handle the water coming out of both field terraces that flow into this pond from adjacent crop field. Wanted to make sure the dam would not breech during an exceptional rain event.
Pictures with descriptions below.
No one would hire me as a concrete contractor. But what I did will work. I dug down about two feet to where the clay was very hard and solid to form a base to hold the concrete block and then drove two T posts down into the bank an additional couple feed and embedded them into the concrete. Added some rebar also.
