Does adding a core ditch to the backside usually work, and is that a procedure that is used on lakes that have a history of leaking, and especially when the base of the back side ofhte dam is always soggy?
Bill I can't tell you what usually works. My best guess would be that it doesn't usually work.
Having said that, the back side of our old farm pond that I can remember back 50+ years (I'm 60) always had a "soft" spot. Had it before dad had it cleaned out with a dozer when I was in grade school and had it after. Always had to remember during wet times to not drive a tractor below the dam or would get stuck and even in dry times it would be soft there. Never thought much about it. Grew up with it.
When I cleaned that old pond out myself in 2013 I found that spot as we were refurbishing the dam. Not wanting to take the whole old dam out, I just dug down as deep as I could go with the dozer. Almost got stuck and barely backed out. Shoved a bunch of clay in and packed best I could with the dozer. Then as I got it solid enough for our rubber tracked tractor and rubber tired pan scraper to go over loaded, packed it down and added several more feet of clay. Basically built another dam on the back side of the old dam and sloped it so we could mow it. The old dam was narrow and steep on the back side.
We no longer have a wet spot there. Did I stop the leak? Maybe, maybe not. I may have just pushed the water lower. There is a seasonal creek right behind the dam and the water may just flow to it now directly rather than surfacing. But at least there is no wet spot and we can mow it. The pond seems to hold water at least as well as other ponds and strip pits in the area as far as how far it drops in dry spells. So while I would not claim it to be jug tight and it may very well leak, it does not leak to a degree I am worried about.
Just my one off experience with trying to stop a leak behind a dam.
