I'm attending Mich with a smaller scholarship than that ($5K). My understanding is that the GSIs are pretty competitive, so I wouldn't necessarily count on that money going in. But if you develop a good relationship with the professors that you would like to work with and excel in their classes, then you can improve your odds of getting a GSI spot. There are some merit scholarships available once you're attending as well, although my understanding is that they are very specific, ie you can only receive a certain scholarship if you are a dual degree ESS student pursuing vehicle emissions research. Not sure if they are all that specific, but you get the idea. I'm in DC as well, so if you're going to Mich and want to grab a beer and chat before the fall please feel free to send me a message.