Hello, I have above ground pond pictured here, my original pond was build by me in 2001 made with rail road ties and it need to be replaced so I rebuilt it in 2014 using 4"x6" pressured tread lumber and installed a new liner which now has development a leak which has caused me a problem. I am letting it leak down enough to maybe find the leak. I had thought about forming it up and pour concrete but not sure how I would seal concrete. no money to hire this work out. Any advise would be greatly appreciated. new pond build in 2014. The corners require the liner to be folded multiple times and I really feel that may be where the leak is, a new liner would also have to be folded in order to form to fill in the corners. This is driving me crazy, not knowing how I need to proceed in making these repairs work long term. Please help.