what size pond?to be safe put some clay on top.i've dug a few ponds and my contractor tells me it's ok if you have a leak are two as long as they are not to bad.they will however fix them selves with time.the guy next to my property dug a small pond about 1/4 acre 2 years ago and dug way to deep and hit alot of sand.it took about 12 months to cap itself off then it started holding water.his pond probably filled up 5-6 times before it held.in my lake we hit sand 2-3 times in small pockets and water would come in and due to the size of the pond we never new they leaked,they filled right up and never dropped.but as i said i would be safe since you have equipment there and pond is dry.