It doesn't snow nearly as much in Green Bay.
I'm wondering a couple things about a grass field.
First, with what they are describing about the stadium all being above ground, steep, with a partial cover that means big shadows. Grass needs light to grow even if you keep the ground warm. The sun angle in WNY is already low in the winter. The season now runs nearly all the way to February. Are they putting grow lights in? If not how will the grass ever heal at all?
Second, if you are keeping the ground warm so the grass grows how do you get the equipment on it to clean off large snowfalls without rutting up the unfrozen field?
Third, if their thought is to resod frequently in the winter where on Earth are they going to truck sod in from and how do they expect that sod not to die, or at least go dormant, in transit? How do you water it in effectively when it's below freezing?