We had an 18" deep pond in our backyard when we moved in 10 years ago. After developing some leaks and other problems we decided to tear everything out and start over. One decision was to dig it deeper, at least 36". When I started digging I found some septic lateral lines about 2' deep that I didn't know were there. Can I just leave the lateral lines where they are now, put in a new liner and live with an 18" deep pond or should I fill it all in and relocate it? The pond now is 9' X 14' X 18" deep.