Originally posted by Edward P. Eitel:
BigPond,
We need a little more information on your current situation.
1. What is the approximate volume of your leak? In gallons per minute what would you estimate the outflow to be?
2. Is the water leaving the backside of your structure muddy or clear? Muddy water is a good indicator that your structure is loosing earth fill and probably compromised.
3. How deep did you dig the core trench? What was the material like at the bottom of the core. Sand, silt, clay, rock, tree roots, etc.
4. How deep is the current pool (water level) above natural ground? The probability of a dam leaking goes up exponentially with the dam height. Even tightly compacted clay leaks to some degree; (.04 inches per hour for example). Small “clear leaks” are generally not of much concern on tall structures. Example – Big Mac in Nebraska leaks, they call the resulting leak, Lake Ogalala.
5. I agree with others in that 20 gpm is probably not enough volume in a 9 acre lake to cover evaporation and seepage. In my neck of the woods I like to use 30 gpm as purely pond maintenance. (no net gain or loss).
6. What type of equipment was used to compact the structures fill? Example – Dozer, Dozer scraper combo, scraper, sheepsfoot compactor, etc.
7. Was the earth fill material of proper moisture content? Dry soils regardless of their texture (sand, silt, clay) compact poorly.
Post a few pictures if possible.
Sorry to hear about your pond and I hope we can be of some help.
Good luck,
Ed
WOW!!! GOOD QUESTIONS!!!
Man this was good STUFF right here.
Ok for number:
1. Man it is tough to say. I look at the "total leakeage about 20 to 30 feet or so from the base of the dam in the creek chanel..Just a quick look, it appears to be maybe 15 gpm give or tak a couple. Like I said I look at it colectivly in the creek channel, and it apears to be this much.
2.
is the water in the back muddy or clearWell it is sort of on the rusty side. I can say that it is NOT muddy. If I may add I have two pipes across the back of my dam about 1/3 of the way up and about 10 feet into the dam. The NRCS called these two drains. They are incased in gravel with a bunch of wholes on the pipe. One goes down the right length of the dam while the other goes down the left and they meet in the center where the water is discharged out.
Now there is some trickle of water coming out of both of these, and it is rust color BUT NOT MUDDY.
Also about 5 feet from the dam just to the right there is a bolder with clear water running over the top of it as well.
But to answer you question, The water apears to be rusty but not muddy.
3.
The core was about 15 to 20 feet deep and was at least as wide as the track hoe bucket. At the bottom it appeared to be a gray silt, a HARD silt, and some of the times we would hit rock. He actually lifted a few bolders out. The core was wide enough in a few places to drive the dozer in it. While he was cutting the core, a dump truck would drop a load right behind where he dug.
4.
At the preasent the pool stands at about 23 to 25 feet deep in the deepest parts and has a surface acrage of about 4 acres right now due to the drought we have had.
The machinery used was a 2 trac hoe's, Dozer, and three dump trucks.
Well I hope this helps...I right now don't know what to do....maybe its not a leak...who knows...I sort of HOPE its not. The only way to REALY know (I guess) is to drain the pond and note the change in the water flow conditions in the back area. But I am starting to not like the idea of draining the pond now, I don't know maybe my heart will change about it later.
I tell you we were VERY cautious when we cut this core, I can't see how I could possibly have a leak!
please HELP!!!
