Re: Old foundation needs replacing???
Great time to have a soils/ structural engineer out to look and tell you the options you have for upgrading the foundation. Many options and prices from a full blown finished basement to pier and beam... Huge price range too. A crawl space foundation sounds like a good place to start considering. But first what matters if you do nothing other then maybe installing a sump pump to extract the water. Again ask Engineer and then get 3 or more bids before you spend $$$$$$$$$
Any an all of my comments are just my opinion and not to be confused with facts.