We dug a pond for our ducks, fenced it in and attached it to the run so they can still play when they aren't allowed to free range. Your lucky your water table is only 10 feet deep, I THINK ours was around 30 ft where we dug the pond. Just keep in mind that the ducks like to "back fill" their own pond so we ran into alot of problems with that. I will have to get more specifics from my hubby at to what his orignal set up actually was when he gets home. Now we basically just have a hole of water for the ducks. Occasionally he will dig the bottom out, especially if the water level starts dropping. He owned an underground utilities company so thankfully we have access to all types of heavy equipment. Retention ponds were something that he did on a regular basis, so he seemed to know what he was doing, lol. He told me it was easier just to scoop the muck out once in awhile to keep the water flowing in, instead of messing with a pump. I currently have 16 ducks and he picks at me by saying they don't make a pumping station big enough to maintain that much poop! We do have clay based soil, so that may make a big difference. One more thing, make sure your ducks do not have access to your pond edges AT ALL. I know you said you were going to use a liner, just make sure you have alot of overhang. Not only will they back fill for you, they will also make their pond bigger.