Compacting soggy dam - 11/11/08 02:20 AM
In the first week of September this year I had an excavator dig out a roughly 20 by 20 foot area on a gentle slope. Test holes that I had dug showed clay and a water table within a foot and a half of the surface all summer long. As this pond was dug on a slope we built a clay berm on the down side. This was created by removing all the topsoil, digging down into the clay and then using the clay from the main hole of the pond to create a dam. The main berm is of good clay about 6 feet wide and rises above the original ground level about 5 feet and is then backed by about 10 more feet of clay top soil which creates a gradual slope to the original ground level.
The hole is only about 6 feet deep at most, but about 3 feet up the side that is dug into the natural clay there is a couple small springs and these filled the pond with about 3 feet of water in the first 3 weeks. Then the water level stopped coming up even though the springs continued to contribute a small amount of water from several inches above the water level.
The water level remained constant for a few weeks and then we began getting fall rains. When we had a good rain fall the pond came up 6 inches but then over a couple weeks of dry weather it lost all this. We just had a few days of heavy rain, about 6 inches in total, and the pond came up a foot, but I am seeing it going down by about an inch a day, even though there is still a lot of visible seepage from the bank at the back plus what has been coming from the two springs.
I guess I have a leak.
Today as I was walking around on the dam I think I found where this is happening. Most of the dam is now quite firm to walk on and seems to have settled some but one area of about 3 by 3 feet is very soft and when I walked on it and noticed this and tried to stomp it down to compact it some more, it got almost jelly like.
I don't see any obvious puddle at the bottom of the berm showing where water is running out.
The guy who did the excavating did try to compact the clay but I think it was difficult as it is a small area with some fruit trees he had to avoid and even at the dry part of the summer the clay was quite wet.
What I am wondering is should I walk a bit every few days on this jellylike spot to compact it, or could this make the problem worse? I am hoping this leak will repair itself as the clay settles. Is it likely our heavy winter rains will cause the clay berm to settle and seal better over the next year? And would it help if I stir up the loose clay on the bottom of the pond to create a lot of clay particles in the water?
I really would like the pond to fill to the top and stay full.
The hole is only about 6 feet deep at most, but about 3 feet up the side that is dug into the natural clay there is a couple small springs and these filled the pond with about 3 feet of water in the first 3 weeks. Then the water level stopped coming up even though the springs continued to contribute a small amount of water from several inches above the water level.
The water level remained constant for a few weeks and then we began getting fall rains. When we had a good rain fall the pond came up 6 inches but then over a couple weeks of dry weather it lost all this. We just had a few days of heavy rain, about 6 inches in total, and the pond came up a foot, but I am seeing it going down by about an inch a day, even though there is still a lot of visible seepage from the bank at the back plus what has been coming from the two springs.
I guess I have a leak.
Today as I was walking around on the dam I think I found where this is happening. Most of the dam is now quite firm to walk on and seems to have settled some but one area of about 3 by 3 feet is very soft and when I walked on it and noticed this and tried to stomp it down to compact it some more, it got almost jelly like.
I don't see any obvious puddle at the bottom of the berm showing where water is running out.
The guy who did the excavating did try to compact the clay but I think it was difficult as it is a small area with some fruit trees he had to avoid and even at the dry part of the summer the clay was quite wet.
What I am wondering is should I walk a bit every few days on this jellylike spot to compact it, or could this make the problem worse? I am hoping this leak will repair itself as the clay settles. Is it likely our heavy winter rains will cause the clay berm to settle and seal better over the next year? And would it help if I stir up the loose clay on the bottom of the pond to create a lot of clay particles in the water?
I really would like the pond to fill to the top and stay full.