Before spending too much time on this, I would just go see the engineering dept in town and ask to see the wetlands map fro NJDEP. Wetlands are defined & buffers assigned. Once you know that, you will know how much unprotected area of the 3 ac is buildable, if any.

There are two kinds of wetlands. One is man made. That is when man installed a road or something else that causes drainage issues. If this is the case the land can possibly be deliniated. If the land is naturally wet and on the books as such with the township engineer then it is impossible to build on it. In most cases you need at least a 50 ft buffer for the structure that you intend on erecting if there is wetlands present. Its always in your best interest to get a perk test and how an engineer provide a report when purchasing land. In general the answer is no. You cannot build on wetlands.