Well, it took a few years, but I finally got back to this old project. A few days after my last post I got started digging the core about 4' wide until I hit hit fresh clay, and then filling it in about 6" lifts with clay that I had saved from the original pond. This is a view of the work from the west side, with the pond on the right and the upstream side to the left.
We started with a packer with a small footprint, figuring it would do a better job, but it broke down, and we had to switch to a larger footprint packer. We got the core up to almost the top of the trench when I ran into a problem with the tractor and had to postpone the project. I covered the trench with topsoil, sodded it, and left it to be completed later. That was in November, 2011.
Just before the predicted rains this past November I finally got back to the project. The first step was to remove the sod and get back to where we had left off two years ago. Here we are using a flat shovel and bucket to locate the original clay core. The white PVC pipe to the right is an irrigation pipe that runs along the edge of the pond.
Then we exposed the rest of the two-year-old clay core.
Next we started adding and packing new clay and added the white PVC overflow pipe and black poly pipe for filling and draining.
I had planned to add more clay to make the dam wider, but a heavy rain was predicted, so we decided to add some temporary top soil and rye grass seed.
If the dam survives the spring rains, then I will drain it, remove the top soil on the sides, add more clay and new top soil, and then add permanent grass sod. Finally, if the dam is still surviving, I will excavate the pond to give a more consistent depth. The frog pond has been a couple feet higher than the main pond since late November, and it seems to be holding water pretty well. It has been essentially full for the last few weeks.
Last night we had a real gully washer, and I half expected to find the whole dam completely washed away. The overflow pipe was totally covered over, but the excess water was flowing around the low area to the west of the dam as it was supposed to.
I do need to add a little more dirt to the west side of the dam to push the overflow area a little farther away from the dam itself, but it's looking like this amateurish job may actually turn out better than I had any right to expect.
This is the view from upstream looking down at the frog pond and the main pond. The frog pond is about six inches above full pool.
This has been a long project, and it has been interspersed with other projects such as finishing the gazebo, planting the birch, cypress, sweet bay magnolias, native azaleas, and other landscaping. And it still has a way to go before it's really done.
I did check the pond again later this afternoon. The dam was still holding. and the level had dropped to the point that the flow was all passing through the overflow pipe. But the best part was listening to the chorus of appreciation from the spring peepers and the upland chorus frogs.
http://youtu.be/maTn8Cn8QTUI just hope the bull frogs return, and that some of them will be smart enough to stay away from the big pond and the LMB that lurk therein.
