So here is the pond in question, notice that the owner are not pumping water anymore and water has stabilized, but now that spring is around the corner, water table is dropping and so is the pond at a rate of 2 inches per day
This picture shows that their deep well is right beside the pond. Although sealed with bentonite, the owner noticed that when the well is used to fill the pond, the pond drops as much if not more rapidly... looks like the well is too close and somehow connected in the bedrock.
This picture shows the clay liner that was added a year after the original excavation. I sampled it and it was our regular sticky blue clay we find around here. The contractor did a nice job, but he is not sure if the spring was covered at the bottom. Sure thing is no clay is behind those rocks, so there is seepage in the sides as well.
This picture shows the general setting; obviously the pond's level is higher than the general surrounding. Owner has seen the sides being wet when the pond is kept full. The problem is obviously two fold, the spring leaks and the sides as well.
So i suggested he drains the pond, seals the spring and bedrock bottom with bentonite, cover the bentonite with that clay they have. Fill the pond and see if there is still that 11500 gal. per day seepage. Next step is to get approval from Seepage Control to see if ESS-13 can be used to further seal the pond. If all fails, he will need to re-excavate and rebuild with a liner... an exercise in patience!
