Hi! Our project has a FAR of 8 (zero lot line, 9 floors) and all open space is located in different green roofs that account for 40% of incorporated vegetated space. 
BUT, we don´t know how to address the soil issues. We have native planting and sedums (very high diversity) and the soil we are using is designed for these type of planting, but it does not match the local reference soils, since it is a green roof soil, which is a completely different issue. 
My guess is that I should clarify this in the Special Circumstances. Am I right? How did you tackle this in your project?

Thanks!