Up here in Minnesota we have huge temp fluctuations, so we'll be digging in footings for an extension on the deck. The soil here is very sandy. I was wondering how close to the pool the footings can go without hurting the integrity of the pool sides. Right now I think there must be a hole in the lining because the water keeps going down lower-now that the ice is off. The pool was installed last year and it's a 30' round. Any advice is welcomed. Thanks.