Philadelphia Green Roof Requirements

[Jimmy O'Connor]

Although Philadelphia offers detailed zoning and use requirements, I am struggling to find concrete information on the requirements for certain bonuses. I was looking for the answers on the Philadelphia Water Department Website but I am confused about what the minimum requirements are that will allow myself and my developers to benefit from the 25% density unit bonus. 

I am reading on the site that it says something about applications for 5,000sf ground disturbance but I have also heard of 13,500 from other developers. Do you NEED to disturb that amount of ground in order to benefit from the bonus OR is the city saying that when you disturb that much earth that you HAVE to have a stormwater plan (green roof being one of the many options). This will greatly affect my ability to pick up commercial lots. Anyone who has experience with this process I would greatly appreciate any feedback! This will make or break a 3,000sf CMX-2 Lot I have been working on.