This probably isn't it, but one thing they are doing is improving the stormwater runoff at the ballpark. I'd never heard of it, but evidently the batting cages and whatever else is located in the very lowest levels of the park get flooded several times a season, whenever there are torrential rains.
They've installed trench drains beneath the warning track along the foul lines and along the outfield walls; they tie into new storm sewers that exit the park at LF or CF and lead to a new stormwater detention facility beneath the parking lot in the little service court between the stadium walls and the scaffolding structure where they shoot off the fireworks.
I know throughout January and February they were working on this and fighting the weather; hopefully it'll all be done for opening day.
Super Bowl XLVII Feb. 3, 2013