Considering that according to Disney it took $30 million just to build the drainage to get the land from being underwater 8 months of the year, I think this wetlands would be a little easier
Are you talking about the original park in the 1970s? Because if so you are talking about a HUGE chunk of land with just the park and then all the roads, parking lots, etc. So yes, that sounds high, but it was a large chunk of land. Wetlands is worked with all the time in Orlando, but some are more of a pain than others. That amount of money could have been spent on easy land because of the sheer size of the land. I am not saying the land you are talking about is easy or hard, but it could be harder. Only someone working at Disney would probably know.
