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
